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  • Articles: DFG German National Licenses  (212)
  • Electronic Resource  (212)
  • Loose Leaf
  • 1990-1994  (212)
  • 1991  (212)
  • Industrial Chemistry and Chemical Engineering  (212)
Source
  • Articles: DFG German National Licenses  (212)
Material
  • Electronic Resource  (212)
  • Loose Leaf
Years
  • 1990-1994  (212)
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Effects of sudden pressure changes in the surrounding gas phase on flow properties of bulk solidsPaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Berlin, September 27 to 29, 1989. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 53-59 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The variation in the behaviour of bulk solids as a result of sudden pressure changes in the surrounding gas phase is of interest in the application of lock hoppers for transfer of bulk solids into pressure vessels. By using such sluice systems, problems occur due to consolidation of the pressurized bulk solids. This paper presents the results of experimental and theoretical research, which allow to describe the influence of several parameters on pressure compensation and the degree of consolidation. With reference to the forces and mechanisms responsible for consolidation, it is possible to describe the different consolidation behaviour of incompressible (limestone) and compressible (hard coal) bulk solids.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140108
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  • 2
    Electronic Resource
    Electronic Resource
    Flow characteristics of large oscillating drops in liquid-liquid systems (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 65-72 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A study was made of the flow characteristics of large oscillating drops of pure liquid-liquid systems, using a thermostatically-controlled, rising drop column, 50 mm in diameter and 1000 mm in length. Mirrors in the jacket enabled front and side views of drops to be photographed simultaneously. Single drops in the size range 5-10 mm were investigated with both mutually-saturated phases and when the solute was being transferred from the dispersed phase. The systems studied were (1) toluene and acetone (dispersed)-water (continuous), and (2) n-heptane and acetone (dispersed)-water (continuous). Acetone concentrations were varied up to 3.75 kmol/m3. The oscillations of a travelling drop were asymmetrical; therefore, the amplitude cannot be expressed accurately in terms of only two axes. The area change of the drop compared to that of a sphere of equal volume ‘ε’, was shown to represent the amplitude accurately. The periods of droplet oscillation were uniform for the mutually saturated systems of constant physical and flow properties but changed when mass transfer was taking place. The interfacial tension exerted a marked effect on the amplitude, which also depended upon the oscillation frequency. The amplitude changed with droplet size in a similar manner to the terminal velocity, i.e. it increased with increasing size until it reached a maximum, subsequently decreasing less rapidly. The drag coefficient increased with increasing rate of mass transfer from the drop. Correlation of the results and the area eccentricity ‘ε’ by dimensional analysis embracing all possible parameters and physical properties affecting drop oscillation, resulted in the correlation ε = 0.22 Sr0.42 We-0.53 M0.13 with a mean deviation of ± 14%. This will facilitate more accurate prediction of the interfacial area for mass transfer calculations, relating to equipment containing droplets in the oscillating regime.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140110
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  • 3
    Electronic Resource
    Electronic Resource
    Development of rate expressions for the catalytic decomposition of nitric oxide with ammonia on iron oxide (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 113-117 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The reduction of nitric oxide with ammonia on iron oxide catalysts has been studied in a continuous-flow recycle reactor using simulated flue gas in the temperature range from 573 to 673 K. NO and HN3 concentrations were varied between 0 and 1000 vpm, O2 and H2O concentrations between 0 and 9 vol.-%, the remainder being nitrogen. In the presence of oxygen, the formulated reaction rate equation describes the measured rates of the main reaction NO + 2/3 NH3 ⇄ 5/6 N2 + H2O. Its form corresponds to the Langmuir-Hinshelwood type. The rate equation well fits the data, which cover the whole industrial temperature and concentration range. In the absence of oxygen, the measured reaction rates can be best described by a power law.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140208
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  • 4
    Electronic Resource
    Electronic Resource
    Vibration induced pneumatic coveyingPaper presented at the Fourth International Conference on Pneumatic Coveying Technology, Glasgow, 26 to 28 June 1990.Dedicated to Professor Dr.-Ing. Alfons Mersmann on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 141-145 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new transport system has been developed which combines vibration of the conveying pipe with amplitudes of the order of fractions of a millimetre with rather low superficial velocities of the carrier gas. This new system was specially designed for gentle transport of fragile particulate materials.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140213
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  • 5
    Electronic Resource
    Electronic Resource
    Safe operation of a batch reactor: Safe storage of organic peroxides in supply vesselsDedicated to Professor Dr. Kurt Dialer on the occasion of his 70th birthday (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 147-161 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this study, we investigated the limits of safe operation for a cooled reactor, operated batchwise. As an example of a single-phase reaction, we studied the decomposition of t-butyl peroxypivalate, a well-known organic peroxide, undergoing self-heating at relatively low temperatures. If sufficiently diluted, it can be supplied to a polymerization process from large, cooled but unstirred vessels. We present a number of extensions to the existing homogeneous explosion theory, namely a practical definition of the critical condition, its calculation, and expressions for the available time before runaway in the case of a supercritical condition, taking into account the effects of natural convection inside the vessel and the reactant conversion. The extensions of the theory were confirmed by adiabatic and non-adiabatic runaway experiments on bench scale, and natural convection cooling experiments with liquids in various packages.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140302
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  • 6
    Electronic Resource
    Electronic Resource
    Three-component mass transfer in liquid-liquid extraction with the system glycerol-acetone-water. Part 1: The influence of vanishing diffusion coefficients in binodal states on the mechanisms of mass transferDedicated to Professor Dr.-Ing. Alfons Mersmann on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 186-191 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This contribution deals with the consequences of the decrease in diffusion coefficients at the boundaries of miscibility in fluid systems and its effect on the mechanisms of mass transfer. The liquid-liquid (1-1) extraction involving several components is taken as an example for the discussion of this topic. A short review of Hampe's theory on transport mechanisms in the transition regions of interfaces [1] explains the intrinsic interdependence between mass and momentum transfer. Finally, a discussion of the peculiarities of resistances to mass transfer in boundary layers, based on the changes in molecular transport properties, is presented.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140306
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of doping with nickel and copper on catalytic behaviour of wide-pore zeolites with different pore structures (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 200-208 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The catalytic properties of wide-pore zeolites, namely Ni- and Cu-doped faujastie H-Y and H-mordenite (H-M) are compared on the example of conversion of n-hexane. After thermal pretreatment of ion-exchanged zeolites, reduction with hydrogen (PH2 ≤ 40 bar) leads to a large number of metallic clusters and crystallites as well as ionic species in the zeolites. Notwithstanding this variety, the different types of catalysts can be divided into three classes: classical bifunctional catalysts (for example NiHM, NiHY) with ion exchange degrees 〉 30%, monofunctional catalysts, such as CuHM and CuHY with high copper contents (ion exchange degree 〉 40%) and metal-doped (Ni and Cu) zeolites which, depending on the conditions of pretreatment, act as bifunctional and/or monofunctional compounds and, therefore, show very unstable reaction behaviour. In addition to the extent of reduction, the cation distribution affects the activity and deactivation behaviour and, to a lesser extent, the product selectivity. The reaction mechanism of bifunctional catalysis is similar to that observed in platinum-doped catalysts, while the mechanism of monofunctional catalysis resembles the process on undoped zeolites.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140308
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  • 8
    Electronic Resource
    Electronic Resource
    Decrease of diffusion coefficients near binodal states of liquid-liquid systemsDedicated to Professor Dr.-Ing. Karl Stephan on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 219-225 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This work investigates the thermodynamically based assumption that diffusion at binodal states of unstable fluid systems vanishes. It is shown experimentally that a scaling law, which describes the fall in diffusion near critical points, may also be applied in an extended form to its abatement at the limits of solubility. These results may profoundly affect the modelling of mass transfer between phases whose bulks exhibit states of saturation.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140402
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  • 9
    Electronic Resource
    Electronic Resource
    Adaptive pole removal control for a batch polymerization reactor (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 240-247 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A systematic method of controller design is introduced to determine the overall charcteristic behaviour developed on process pole removal. The time delay compensation is automatically incorporated in the proposed control law. The implemented tuning parameters in the law are confined to the range between 0 and 1 to guarantee the stability of the overall control system. Subsequently, the fixed and adaptive control strategies are implemented to simulate a batch PVC reaction system. The adaptive control scheme provides good, roubust control of this simulated reactor notwithstanding the wide range of operating conditions and non-linear dynamics of the system. However, the fixed control scheme performs well only for a noise-free system. In addition, two limiting control laws, derived from the proposed method, are also used to simulate the reactor. The results indicate that these laws are not suitable for this non-linear reaction system.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140405
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  • 10
    Electronic Resource
    Electronic Resource
    Three-component mass transfer in liquid-liquid extraction with the system glycerol-acetone-water. Part 2: Calculation and experimental investigation of three-component mass transfer in a countercurrent extraction column (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 253-263 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article describes the effects which occur during three-component mass transfer in liquid-liquid extraction between saturated and undersaturated phases of the system glycerol-acetone-water. The description is based on experiments in a countercurrent spray column. The physical modelling starts with the balance equations of phase flows, taking into account the variation of concentrations and mass flow rates along the column axis as well as backmixing effects. In addition, recent findings on the mechanisms of mass transfer in saturated and undersaturated phasses, deduced from theoretical and experimental results, were used to formulate mass transfer coefficients. These are valid for the region near the interface of drops in a fluid and are inserted into the balance equations. A comparison between experiments and calculations of the observed phenomena is presented.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140407
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  • 11
    Electronic Resource
    Electronic Resource
    Photosensitive materials for use in velocity profile measurements in the water phase of air-water systems and in single phase liquid systems (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 275-287 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Those chemical and photochemical characteristics of a photochromic system which are necessary for successful application to flow visualization studies in water are identified. The properties of a number of photochromic and photosensitive systems are discussed, and critically examined, with regard to these requirements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140410
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  • 12
    Electronic Resource
    Electronic Resource
    Simulation of a distillation column on an IBM PC, accounting for real behaviour of electrolyte solutionsPaper presented by A. Bosen at the “Jahrestreffen der Verfahrens-Ingenieure”, Stuttgart, October 3 to 5, 1990. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 295-300 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This contribution demonstrates the possibility of using a thermodynamic description of electrolyte solutions directly for computer simulation of distillation columns. Coefficients are determined for a combination of a solvation model with a local composition equation for the activity coefficient. The use of one set of coefficients yields good results of calculation of vapour pressure, vapour phase composition and caloric data of hydrochloric acid. Solution of material and heat balance equations of distillation columns is achieved on an IBM PC with the above description. Two illustrative examples of an absorption and a rectification calculation are presented
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140502
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  • 13
    Electronic Resource
    Electronic Resource
    Calculation methods for multicomponent adsorption equilibriaPaper presented by S. Scholl at the “Jahrestreffen der Verfahrens-Ingenieure”, Stuttgart, October 2 to 5, 1990. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 311-324 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The knowledge of multicomponent adsorption equilibria is of great importance for the industrial design and application of adsorptive purification and separation processes. As the experimental determination of the required data is time-consuming and costly, theoretical help is desirable. This contribution presents and assesses the most common theoretical approaches to the calculation of multicomponent adsorption equilibria. The models are based on the assumption of an adsorbed solution, extension of the volume filling of micropores theory or statistical thermodynamics. These models are applied to different adsorptive/adsorbent systems with ideal and non-ideal equilibrium behaviour. It is established that, at low coverages of adsorbent surfaces, all theories provide good estimates of the adsorbed phase composition and total loading while, at high saturations, no model is completely satisfactory.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140505
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  • 14
    Electronic Resource
    Electronic Resource
    Theoretical analysis of gas stripping performance of spray towers (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 347-352 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simplified model has been developed to describe ammonia stripping process in spray towers. The effect of various operating parameters including air flow rate, contact time, droplet size, liquid to gas ratios and tower height on the performance of such systems has been studied in detail. The results obtained for ammonia stripping have been compared with the limited experimental data available in literature. The predicted results agree reasonably well with the reported experimental data.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140508
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  • 15
    Electronic Resource
    Electronic Resource
    Particle structure change of CaO during high temperature sulphatization (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 357-362 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of particle size (layer thickness), BET surface area and pore size distribution on the reactivity of CaO derived from limestone were studied by using a pH-stat and the BET method. Visual analysis was obtained with SEM, and X-ray diffraction was used to determine the crystalline components present. It was found that the pore size distribution, including pore volume and pore surface distribution, affected the sulphatization behaviour. The larger pores (D 〉 50 Å) with their pore volume and pore surface were to some extent responsible for both initial reactivity and ultimate capacity of CaO.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140510
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  • 16
    Electronic Resource
    Electronic Resource
    Infinite-dilution activity coefficients of organic solutes in methyl phenyl ether, butyl ether and methyl iso-butyl ketone (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 376-378 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Activity coefficients of hydrocarbons and chloroparaffins at infinite dilution in methyl phenyl ether, butyl ether and methyl iso-butyl ketone at 293.15 K have been obtained by the retention-time method in a modified gas chromatograph. The experimental data are compared with predictions of the UNIFAC and MOSCED models. Selectivities for the 1,1,1-trichloroetane-1,2-dichloroetane separation process are reported.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140603
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  • 17
    Electronic Resource
    Electronic Resource
    Equilibrium model for CO2 absorption in an aqueous solution of 2-amino-2-methyl-1-propanolRevised form of a paper presented at the 40th Annual Laurance Reid Gas Conditioning Conference, University of Oklahoma, Norman, Oklahoma, March 5-7, 1990. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 394-398 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A semi-empirical gas-liquid equilibrium model for the absorption of CO2 in aqueous 3M AMP (2-amino-2-methyl-1-propanol) is presented. It applies to high CO2 loadings (y 〉 0.5) in the temperature range between 20 and 50 °C, and is based on experimental solubility and pH determinations. For a given amine concentration, it yields the equilibrium partial pressure of CO2 as a function of only two variables: the CO2 loading and temperature. The model correlates the expressions for the chemical equilibria involved as follows: pCO2 = m y × 10x, where pCO2 is the equilibrium partial pressure, x = logK - pH, m is the amine molarity, y the CO2 loading, and K is a parameter involving Henry's law constant, H, and the first dissociation constant, K1, of carbonic acid. pH is found to depend on both temperature and CO2 loading while logK depends only on the CO2 loadIng. Correlations for pH and logK are presented. The model fits own data for 3M AMP very well as well as the equilibrium data found in recent literature.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140606
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  • 18
    Electronic Resource
    Electronic Resource
    Characterizing the Structure of Fumed Pigments using the concepts of fractal geometryDedicated Professor Kurt Lesconski on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 63-71 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Many commercially important pigments such as titanium dioxide and carbonblack are produced as fumes from a combustion process. The fuming process generates open structured agglomerates conforming to a morphology predicated by physical considerations. For this reason widely different chemical pigments often manifest common physical structure. This structure can be characterized using the concepts of fractal geometry. In this communication the potential usefulness and physical significance of descriptive parameters of the agglomerate structure of fumed pigments based on the concepts of fractal geometry are explored. Similar structures present in high energy ceramic powders are discussed and the potential importance of fractal dimension parameters for the prediction of the physical behaviour of powders is outlined.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080112
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  • 19
    Electronic Resource
    Electronic Resource
    Particle Growth by Coalescence and AgglomerationDedicated to Professor Kurt Leschonski on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 86-89 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A dispersed system is considered which will form its condensed phase at high temperatures and is characterized by a high density of very small supercritical nuclei. It is assumed that particle growth is determined by coagulation and (viscous flow) coalescence. The morphology of the final particles depends on the temperature history of the formation process. Compact spherical particles and agglomerates may be formed. Agglomerates result when the process temperature decreases to an extent that coalescence is quenched in the course of the growth process. The average size of the primary particles in the agglomerates is calculated by using the analysis and the approximations described in a previous paper. The growth kinetics of the primary particles are presented in a dimensionless form. The results show that the dimensionless size of the primary particles depends only on the ratio of two characteristic lengths of the system. For small values of this ratio, the size of the primary particles composing the agglomerates, although much greater than the initially formed nuclei, is independent of the volume fraction of the condensed aerosol. For large values of this parameter, the theory merges into the classical theory of perfectly coalescing spheres.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080115
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  • 20
    Electronic Resource
    Electronic Resource
    Announcement (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 100-100 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080118
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  • 21
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    Electronic Resource
    An Estimate of Some Statistical Properties of Extinction signals in dilute and concentrated suspensions of monosized spherical particlesDedicated to Professor Kurt Leschonski on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 95-99 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A statistical analysis is made for the extinction of radiations in suspensions, whereby the whole range of possible particle concentrations is covered. The extinction signals are characterized by their average value and by a characteristic length of fluctuation. For simplicity, the considerations are restricted to geometric ray propagation in dispersions of perfectly absorbent, monosized spherical particles. An extinction equation is derived, which reduces to Lambert-Beer's law in the limit of low particle concentrations. For higher concentrations, significant deviations from Lamberg-Beer's law due to steric particle-particle interactions are predicted. The characteristic length of the fluctuations is a function of particle diameter and transmission and has a broad minimum with medium transmissions, allowing for maximum resolution with measurements in this range.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080117
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  • 22
    Electronic Resource
    Electronic Resource
    The Analysis of Dust Cake Structures (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 105-109 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The operational characteristics of cake-forming filter apparatus are strongly influenced by the structure of the dust cake formed. The quantitative evaluation of sectional images of loosely bound filter cake deposits is introduced. First the techniques with which the dust cake is prepared and with which scanning electron micrographs may be obtained are described, together with the subsequent digitization by video and computer equipment. This is followed by a comprehensive description of the evaluation of the digitized images, with special emphasis on the determination of the deposit's porosity and the computation of the particle and pore-size distributions at selected locations. Finally, results derived from a true filter cake are presented.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080120
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  • 23
    Electronic Resource
    Electronic Resource
    Influence of the Particle Size Distribution on the flow behaviour of fine powders (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 101-104 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Some results are presented of investigations on the flow behaviour of very fine α-alumina powders having different particle size distributions. Shear tests were performed in a translation shear cell. The humidity was in the range 0.3 〈 pD/pSD 〈 0.6 in order to ensure the formation of adsorbed water layers only and to exclude capillary condensation. In the region of adsorbed layer bondings, the flow behaviour of very fine powders deteriorates in comparison with regions where no adsorption layers exist. An extrapolation of the unconfined yield strength for very low consolidation stresses results in an approximately constant value for different particle size distributions. In contrast, the slope of the linear function σc = f (σ1) increases with decreasing particle size up to a certain limit. For narrow particle size distributions, there is a pronounced decrease in the bulk density with decreasing particle size. Further, the bulk density is strongly influenced by the width of the distribution.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080119
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  • 24
    Electronic Resource
    Electronic Resource
    Sieving Capture of Liquidborne Particles by microporous membrane filtration media (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 142-150 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Test methodology has been developed to measure the particle removal efficiency of microporous membrane filtration media under conditions in which sieving is the dominant particle capture mechanism. The methodology was used to determine the particle capture efficiency of a 0.45 μm membrane filter for removal of submicrometer sized particles from DI water. Particle capture was found to be a strong function of particle diameter, filter media thickness, and filter loading. Particle removal efficiency increased with increasing particle diameter and media thickness. It decreased with increased filter loading when the filters were challenged with the smaller particles used in this study. Removal efficiency initially decreased then subsequently increased during loading with larger particles. Capture was independent of filtration velocity and particle concentration. A sieving model was developed to predict particle capture by the filter media as a function of particle diameter, filter thickness and filter loading. The model was found to accurately predict breakthrough of monodisperse particle suspensions through the media. Particle breakthrough occurred more slowly than predicted when the filters were challenged with a polydisperse particle suspension.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080126
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  • 25
    Electronic Resource
    Electronic Resource
    Announcement (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 173-173 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080131
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  • 26
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    Electronic Resource
    The Work of the British Standards Institution in Particle, surface and pore size characterisationPresented at the Coulter Classics Symposium, Solihull, September 26-27, 1989. (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 170-172 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: British Standards committee GME/29/4 is concerned with “Particle sizing methods other than sieving”. Its work covers not only particle size distribution analysis but also methods of estimation of surface area and pore size distribution, as well as a glossary of terms relevant to those subjects. The current British Standards in the BS 3406 series (particle size analysis) and BS 4359 series (surface area) are reviewed, and a progress report is given on the status of several new and revised Standards which are in preparation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080130
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  • 27
    Electronic Resource
    Electronic Resource
    A Procedure for Blending and Mass Balancing fine particle size data (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 164-169 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An increased interest in the development of new techniques for fine grinding has resulted in a growing concern over the accuracy of size distributions for extremely fine particles. Since most particle size analyzers have lower detection limits, care must be taken when comparing size distributions which have not been properly mass balanced.An automated technique has been developed in which a completely mass balanced size distribution can be obtained using an Elzone 80XY particle size analyzer. A computer program is used to blend the data from successively smaller orifice tubes, and to determine the weight percent of material finer than the lower detection limit of the analyzer. This result is then used to correct the distribution for the missing fine material. Experimental results indicate that size distributions obtained using this procedure are reproducible and compare favorably with those obtained using other size analysis techniques.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080129
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  • 28
    Electronic Resource
    Electronic Resource
    Announcement (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 173-174 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080132
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  • 29
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    Electronic Resource
    Development of an Automatic System for Measuring Particle Charge and Size distributions in a clean room (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 200-208 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An automatic measuring system was developed to perform simultaneous measurements of particle size and charge distributions in a clean room and other aerosol sources. The system consists of an electrostatic condenser (EC) and an optical particle counter (OPC), which are controlled by a personal computer (PC). The PC automatically varies the voltage on the EC and converts the corresponding OPC counts to charge distributions. The reliabilities of the data inversion method and the automatic measuring system were confirmed by theoretical and experimental examinations, respectively. In the theoretical examination, inverted charge distributions were tested and compared with various assumed input distributions. In the experiment where monodisperse aerosols neutralized by a 85Kr neutralizer were used, the measurement results agreed well with the theoretical Boltzmann charge distribution. The application of this technique is demonstrated by the measurement of charge and size distributions of aerosols in a clean room.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080137
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  • 30
    Electronic Resource
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    A Comparative Study on Different Scattering Techniques and data evaluation methods for sizing of colloidal systems using light scattering (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 274-281 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Quasi-elastic light scattering, elastic light scattering and Fraunhofer diffraction can be used for optical particle sizing. Simulated data were used to compare the different scattering techniques in terms of resolution and range of applicability. Elastic scattering techniques have a ten times higher resolution but cover a smaller size range than quasi-elastic light scattering. The most important inversion techniques for data evaluation for such experiments were also compared. Regularization techniques with positivity constraints and interpolating cubic B-splines proved to be superior to truncated singular value decomposition and maximum entropy methods.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080150
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  • 31
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    Measurement of Polydisperse Colloidal Suspensions with quasielastic light scattering (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 259-266 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The measurement of polydisperse populations of colloidal particles with quasielastic light scattering (QLS) is a common and dangerous practice. Here intensity autocorrelation functions with different linewidth distributions are simulated. The simulated data are treated with the histogram and exponential sampling methods and the results are contrasted with the results of the Laplace inversion routine of Provencher. All methods work well in calculating the size distribution from noise-free correlation functions. In analyzing noisy data the methods may produce results that bear no relation to the true size distribution. The histogram method fails to determine size distributions from noisy simulated and real correlation functions. The exponential sampling method gives a qualitative measure of the size distribution when the required resolution does not exceed the limitations set by noise theory. Provencher's routine extracts smooth unimodal distributions very accurately even from noisy correlation functions, but determination of bimodal distributions may be unreliable. The importance of taking data at many scattering angles is emphasized and experimentally determined size distributions of samples of polystyrene latex spheres measured at multiple scattering angles are presented.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080148
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  • 32
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    Electronic Resource
    The Physically Relevant Parameter Space of the Nukiyama-Tanasawa distribution function (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 287-293 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The range of the parameters of the Nukiyama-Tanasawa distribution function was analysed, leading to the identification of the physically relevant parameter space. The analysis was also applied to the Rosin-Rammler distribution function.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080152
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  • 33
    Electronic Resource
    Electronic Resource
    Regularized Inversion of the Laplace Transform: Accuracy of analytical and discrete inversion (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 282-286 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dynamic light scattering is a technique used for the optical determination of a colloidal particle size distribution. A simple procedure, based on a trapezoidal model for the linewidth distribution function, is given for obtaining a constrained regularized inversions of correlation data obtained in dynamic light scattering experiments, and estimating the accuracy of such inversions. Based on the eigenfunction decomposition of the Laplace integral equation, error bars, which are directly related to the accuracy of the correlation data, may be placed on both analytical and discrete inversions. By using a regularization procedure, and a nonnegativity constraint, problems with statistical noise in data may be handled effectively.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080151
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  • 34
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    Electronic Resource
    Mass Calibration of the Coulter Counter Model ZM (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 294-296 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The calibration of electrical sensing zone instruments is normally achieved by using spherical particles with a certified size. An alternative and more fundamental procedure, known as mass or self-calibration, is to use particles of the material under test.This work concerns the mass calibration technique, in particular the equations used to calculate the mass calibration constant. It is demonstrated that some of the published expressions are inconsistent. An expression particularly suitable for the Coulter Counter Model ZM has been derived and validated. Some experiments were also performed using irregular particles, in order to compare both calibration methods.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080153
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  • 35
    Electronic Resource
    Electronic Resource
    Control and Use of a Miniaturized Droplet Generator (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 297-300 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A miniaturized droplet generator with some new features, working on the principle of laminar liquid jet instability and break-up was designed. The instrument has been used to study the dispersion of monosized droplets in a turbulent swirling flow, exhibiting the main features of combustion chamber flows of modern gas turbines.The operating range of the generator was evaluated by phase-Dopper anemometry (PDA). It was demonstrated that the device also works in some metastable operating modes, producing coherent droplet streams with very small standard deviations for drop size and drop velocity. Special attention was directed to the reliability of the device and to the control of drop size. The PDA measurements showed that, in contrast to the evaluated optimum excitation frequency, the drop size cannot be determined from the orifice diameter.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080154
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  • 36
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    Electronic Resource
    Design Data for Cyclones (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 301-307 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For many years efforts have been made to describe the complex process of particle separation in cyclones, and a multitude of separation models have been set up. A comparison of such separation models fails because insufficient usable test results are available and systematic and precise investigations are missing.It is important for the design of cyclones to rate their separation properties by means of the fractional collection efficiency. On account of the known measuring problems, the data supply of reliable fractional efficiency curves of cyclones is still too small. Fractional efficiency as a function of the entrance velocity was measured with a high-speed optical measuring technique. Measurements of low dust concentrations are presented. Geometrically similar cyclones of four different sizes were investigated. The fractional efficiency curves are plotted versus dimensionless parameters and the validity of the design criteria gained in this way is shown. The influence of particle shape on the fractional efficiency curves is discussed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080155
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  • 37
    Electronic Resource
    Electronic Resource
    Announcement (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 323-323 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080158
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  • 38
    Electronic Resource
    Electronic Resource
    Performance of Disposable Respirators (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 308-314 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental study of the filtration performance of several commercially available, NIOSH-approved, disposable respirators was conducted using monodisperse DOP and NaCl particles with diameters in the 0.035 to 4 μm range.The aerosol penetration through the respirators were measured at flow rates of 16, 28 and 48 L/m using a condensation nucleus counter, an aerodynamic particle sizer, and a laser optical particle counter for purposes of comparison. The results obtained by these instruments were found to be in good agreement with each other in the overlapping region of particle size of the instruments.The peak penetration through the respirator filters was found to range from approximately 1.2% to 30% at 16 L/m, 3.5% to 37% at 28 L/m, and 6% to 45% at 48 L/m. The most penetrating particle size was found to lie in the 0.1 to 0.4 μm diameter range. Further, no significant difference in penetration for NaCl and DOP particles was found, suggesting that the particlebounce effect was not important in the present study.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080156
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  • 39
    Electronic Resource
    Electronic Resource
    Drop coalescence on inclined plates in liquidsDedicated to Professor Kurt Dialer on the occasion of his 70th birthday (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 11-19 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inclined plates are often installed as mechanical separation aids in gravity settlers for the separation of liquid-liquid systems. The authors investigated the process of coalescence of single drops on trickling films flowing off inclined plates. The method of investigation was developed by Blass and Rautenberg. It ensures that, under certain conditions, only hydrodynamic parameters influence the coalescence process to any significant extent. The coalescence time of the drops characterizes the process of coalescence. Short time between 1 and 3 seconds provide favourable conditions for coalescence whereas long times, often ten times as long or even longer are unfavourable. This contribution introduces a criterion for clear demarcation between these two ranges and also a determination of separation parameters for favourable conditions for coalescence. Furthermore, the function of the plates is described, which is determined by hydrodynamic and wetting processes. The characteristic operating regions of a plate are shown in a working diagram.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140103
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  • 40
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    Effect of mixing behaviour on gas-liquid mass transfer in highly viscous, stirred non-newtonian liquidsPaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Berlin, September 27 to 29, 1989. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 1-10 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When declaring and using process engineering data such as, for exmple, mixing times or kLa values, it is assumed that these apply to the entire reactor contents. The condition of uniform mixing, necessary for this, is generally met in the regime of turbulent flow. When highly viscous and, above all, strongly non-Newtonian liquids are stirred in small reactors, there are frequently also regions of laminar flow and completely stagnant zones, which are only partially mixed or not at all. The present paper pursues the question to what extent is the gas-liquid mass transfer in stirred, highly non-Newtonian liquids influenced by the mixing behaviour of the reactor. The results show that, below certain Reynolds numbers, three relatively distinct regions exist, with different mixing intensities. Between an almost ideally mixed region in the vicinity of the stirrer and a completely stagnant and dead one, there is a zone of very slight motion. This finding demonstrates that the usual determination of integral or volume-based data in the literature is neither logical nor adequate for the case under consideration. Thus, the gas-liquid mass transfer takes place mainly in the relatively well mixed region. Therefore, use of a kLa value also requires the volume of this region to be declared. Only the knowledge of this volume enables us to correlate the kLa values in such a way that the sorption characteristics thus obtained appear suitable for scale-up. This procedure, which is illustrated by numerous examples of measured results for different stirrers, is important whenever design data for highly viscous liquids are to be worked out on the basis of laboratory measurements. Only when larger equipment is used, in which turbulent flow can be achieved, this problem does not arise because of the relatively uniform mixing of reactor contents.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140102
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  • 41
    Electronic Resource
    Electronic Resource
    Modelling of pressure drop in packed columns (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 89-95 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The correct choice of packing is of decisive importance for optimum process efficiency in the operation of two-phase countercurrent columns. An important criterion for this choice is the pressure drop in the gas flow. Theoretical relationships are derived for calculating the pressure drop in beds with dry and trickle packings. It has been demonstrated by comprehensive experiments that these relationships allow the pressure drop to be determined more accurately than by previous methods. The experiments were performed at the Department of Thermal Separation Processes of Bochum University on 54 different packed beds, using 24 different systems.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140203
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  • 42
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    Calo-visco-densimeter: A multipurpose apparatusPaper presented by H. Zech at the “Jahrestreffen der Verfahrens-Ingenieure”, Berlin, September 27 to 29, 1989.Dedicated to Professor Dr.-Ing. Karl Stephan on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 109-113 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A multipurpose apparatus was designed, built and operated with the aim of a simultaneous determination of enthalpy of mixing, heat capacity, kinematic viscosity and density of liquid mixtures at 240 〈 T 〈 370 K and 1 〈 p 〈 25 bar. Its operation was monitored by a PC. Details of design and the first experimental results are presented.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140207
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  • 43
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    Application of dynamic programming to high-dimensional systems described by difference equationsPaper presented by R. Luus at the Second North American/German Workshop on Chemical Engineering Mathematics and Computation, Göttingen, Germany, July 15-20, 1990. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 122-126 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The application of dynamic programming using an interative procedure, which employs domain contraction and accessible grid points for the state vector, is investigated for solving optimal control problems where the system is described by a set of difference equations. A model of a gas absorber with six state variables and two control variables is used to examine the feasibility of the proposed algorithm and to analyze the effects of the grid size and of the domain contraction factor. This algorithm yields rapid convergence to the optimum even when a relatively coarse grid with as few as 11 grid points is used.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140210
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  • 44
    Electronic Resource
    Electronic Resource
    Masthead (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140301
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    Studies of drop break-up in liquid-liquid systems in a rotating disc contactor. Part II: Effects of mass transfer and scale-up (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 178-185 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The number fraction of drops of a given size which break up at rotor level in a rotating disc contactor has been observed during mass transfer in either direction to or from solvent or aqueous drops. Critical rotor speeds for a given drop size undergoing mass transfer can be used to find an effective interfacial tension. Using this interfacial tension value, the break-up fractions are correlated within experimental uncertainties in the same manner as for no mass transfer. Drop break-up fractions depend on column size and relevant empirical correlations of the data are presented. The results may be used to estimate the effect of mass transfer on drop size distributions in an RDC.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140305
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  • 46
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    Non-steady-state catalytic decontamination of waste gases (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 209-212 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The non-steady-state behaviour of a fixed bed reactor controlled by periodical direction reversal of reactant feed, applied in catalytic oxidation of industrial waste gases, containing organic compounds and carbon monoxide, has been investigated. The effects of the type of oxidized compound, its initial feed concentration, linear gas velocity, inerts-to-catalyst ratio and inerts thermophysical characteristics on the formation of reactor concentration and temperature fields were elucidated. It was shown that autothermal reactor behaviour is guaranteed by concentrations of the oxidized component which ensure an adiabatic temperature increase in excess of 20 °C. Deviations of either flow rate or initial concentration of the oxidized compound do not disturb the operational stability.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140309
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  • 47
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    Influence of intraparticle total pressure change on pore mass transportExtended version of poster presented by S. Scholl at the “Jahrestreffen der Verfahrens-Ingenieure”, Berlin, September 27 to 29, 1989. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 213-218 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Influence of intraparticle total pressure change on pore mass transport is investigated in physical gas phase adsorption of a single component from an inert carrier medium. The Dusty Gas Model is applied to quantify pore mass transport, assuming local equilibrium between pore fluid and adsorbed phase. Calculated results for single pellet adsorption kinetics of cyclohexane on activated carbon and CO2 on molecular sieve 5 Å are compared with experimental data. It is found that the total pressure drop in the pore system may be as much as 1% of the ambient total pressure. This results in a maximum viscous flow contribution of 13% for the cases studied. Since this contribution is obtained only under conditions of low overall transport rates of the adsorbed component, the assumption of isobaric conditions within the pore system of a porous adsorbent appears justified for most cases of practical calculations.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140310
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  • 48
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    On the falling-rate period (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 234-239 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A fixed bed of glass particles, wetted with water, was dried from above. The measured moisture profiles within the sample show that its surface is not completely dry during the falling-rate period. Hence, the current view, according to which the moisture front retreats into the sample directly after reaching the critical moisture content, has to be revised. Assuming that parallel dry and wet channels form within the sample during the constant-rate period, the onset of the falling-rate period depends only on the diameter of these channels. If the moisture is distributed very finely, a large number of channels with a small diameter have to be considered. The falling-rate period for this system occurs at low moisture contents. For a coarse distribution of moisture, fewer channels with a large diameter should be assumed. Their drying rates show the beginning of the falling-rate period already at high moisture contents. A good agreement between measured and calculated drying rates could be achieved by fitting the channel diameter. Only for very low moisture contents, is the agreement poor. This is to be expected, because the measured moisture profiles show a completely dry sample surface for these moisture contents, indicating that the moisture front has already retreated into the sample.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140404
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  • 49
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    An automatic laboratory reactor for homogeneous polymerization of methyl methacrylatePaper presented by U. Budde at the “Jahrestreffen der Verfahrens-Ingenieure”, Berlin, September 27 to 29, 1989. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 134-140 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An automatic stirred tank reactor of laboratory scale has been developed for on-line measurement of conversion, viscosity, and molar mass distribution of homogeneous polymerizations. For these on-line measurements, a fraction of the reaction mixture is bypassed through a densimeter and a viscometer. Samples are taken at intervals of 15 min, diluted semi-automatically, and then injected into a high performance gel permeation chromatograph for determination of the molar mass distribution of the polymers. A microcomputer collects the measured data, calculates the monomer conversion and the output data for different control units. In this study, methyl methacrylate is polymerized batch- and semi-batchwise with ethyl acetate as solvent and in the presence of different initiators. The semi-batch polymerizations are carried out at constant reaction rate by feeding the initiator and at a given increase in viscosity by feeding the solvent.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140212
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  • 50
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    Fluidized bed dryers: Dynamic modelling and control (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 307-310 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fluidized bed drying finds important applications in the chemical industry on account of the following advantages: (a) rapid exchange of heat and mass between drying media and particles yields the desired product quality and reduces the overall drying time and (b) easy handling of feed and product. There is much scope for improving the existing modelling techniques as applied to predicting the performance characteristics of the dryers. This should provide a sound basis for the implementation of appropriate control strategies. This report is a review of prevailing modelling, identification techniques and control strategies. Hopefully, the up to date information in this paper will be found useful for research work on fluidized bed dryIng.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140504
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    Simulation of fluidized-bed reactors for catalytic oxidative coupling of methane to C2-hydrocarbonsPaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Stuttgart, October 3 to 5, 1990.Dedicated to Professor Dr. Dr. h.c. Dieter Behrens on the occasion of his 65th birthday (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 325-333 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The “bubble assemblage model” of Kato and Wen was applied to simulate the catalytic oxidative coupling of methane to C2-hydrocarbons in a fluidized bed reactor. Simulation results were compared to experimental data obtained in a laboratory-scale fluidized bed reactor. To improve the accuracy of predictions, the influence of fluid bed hydrodynamic and kinetic submodels was investigated by applying a sensitivity analysis. It was shown that the most important element in the model is the applied reaction scheme; the consecutive reactions of C2 hydrocarbons occurring most probably in the gas phase should be considered.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270140506
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    Sensitivity analysis in static optimization of fermentation plantsPaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Stuttgart, October 3 to 5, 1990. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 353-356 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biotechnological processes are often characterized by uncertain model parameters, input variables which are difficult to handle and ill defined cost functions. Nevertheless, it is desirable to define optimal operating points. Starting with a robust approach for numerical optimization, the paper presents three different methods for evaluating the sensitivity of an optimal operating point to uncertain parameters or disturbances of the input variables. It is shown that sensitivity analysis can provide useful guidelines for designing biotechnical plants with invariant optimum operation in the presence of changing inputs or parameters.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140509
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  • 53
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    Method of multiobjective optimization for imprecise objectives (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 363-366 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method of multiobjective optimization for imprecise objectives is presented. The problem consisted in a minimization of the distance between the set of admissible solutions and an ideal point. Applicability of the method is illustrated by the choice of best impeller from a group of seven different types tested. The optimum process conditions were selected, taking as optimization objective the maximization of kLa and minimization of PG.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140511
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  • 54
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    A multi-parameter model for absorption (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 379-385 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A three-parameter model for mass transfer by absorption, based on a combined effect of non-steady-state molecular and eddy diffusion through a resistance zone has been suggested, which encompasses all the existing theories on mass transfer at the gas-liquid interface. King's approach [5] to describing gas-liquid mass transfer phenomena through an eddy-diffusivity model can explain some experimental results, but does not provide a general mathematical solution of the problem. The shortcomings of the King's model are overcome in the present work and a general solution is presented. This solution confirms the experimental findings of Versteeg et al. [10] for liquid phase mass transfer. The steady-state solution of the present theory, valid for the dimensionless number α 〉 0, shows a close agreement with experimental data of Luk [22], the only source of all the information necessary for model verification.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140604
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  • 55
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    Hydrodynamics in a pressurized cocurrent gas-liquid trickle-bed reactor (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 406-413 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of gas density on total external liquid hold-up, pressure drop and gas-liquid interfacial area, under trickle-flow conditions, and the transition to pulse flow have been investigated with nitrogen or helium as the gas phase up to 7.5 MPa. It is concluded that the hydrodynamics depends on the gas density and not on the reactor pressure. At higher gas densities, the operating region for trickle flow becomes larger while the gas-liquid interfacial area increases only slightly. Pressure gradient and liquid hold-up are considerably affected by gas density and correlations have been derived for these parameters.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140608
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  • 56
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    Masthead (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140601
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    Impact of particle size dispersity on thermal conductivity of packed beds: Measurement, numerical simulation, predictionPaper presented by E. Tsotsas at the “Jahrestreffen der Verfahrens-Ingenieure”, Stuttgart, October 3 to 5, 1990. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 421-427 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of particle size dispersity on thermal conductivity of packed beds without fluid flow is investigated. For this purpose, new experimental data for bi- and polydispersed packings are presented and data from the literature reviewed. All data are tabulated. The results of numerical calculations carried out for regular arrangements of spheres are also discussed. The impact of particle size dispersity on thermal conductivity is shown to be primarily due to the change in bed porosity. Thus, prediction can be carried out in the same way as for monodispersed packings if based on the actual bed porosity. A model developed by Schlünder and co-workers is revised and recommended for practical application.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140610
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  • 58
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    Masthead (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991) 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080101
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    A New Air Classification Principle for the Particle Size range d 〈 5 μmDedicated to Professor Kurt Leschonski on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 8-11 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Requirements for processes for air classification for the particle size range d 〈 5 μm are described. A classification principle and first experimental results are presented.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080103
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    Preparation Technology for Fine Particle MeasurementDedicated to Professor Kurt Leschonski on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 1-7 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Describing the disperse state is important for quality assurance, operational safety and the design and modelling of processes, especially in solids technology. Starting materials, intermediates and end products have to be characterized. Apart from representative sampling, preparation greatly influences the results of particle characterization. Very fine particles are normally agglomerated unless a highly dispersed state is stabilized by an additive. For a meaningful measurement, they must be preserved in this state or be definitely dispersed, depending on the type of problem.If the point of interest is the present disperse state with regard to the processing characteristics, e.g. for a filtration, the system should not be changed by the preparation method. If it is necessary to determine the property functions, i. e. the functional relationship between technological and physical properties, it is necessary in general to use a high dispersion energy or a long dispersing time in order to obtain the best achievable dispersion. The finer and more unstable a disperse phase is, the more the correct processing is important for the result. The problems of dispersion in gases and liquids are discussed with some examples.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/ppsc.19910080102
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    Measurement of the Influence of Directed Particle motion on the turbulent particle deposition velocity by means of laser-doppler anemometryDedicated to Professor Kurt Leschonski on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 12-15 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The dry deposition of particles from the atmosphere is not well understood for reasons of surface variabilities and mutual interactions between surface and particles. However, even relatively simple influences of physical parameters have so far resisted successful parameterization, although some progress has been achieved. There is no general way to determine the relative contributions of stochastic turbulent and Brownian diffusion and directed motions (i. e. sedimentation) to the total deposition velocity since they contribute in a nonlinear manner to the total deposition velocity. The directed motion is an unknown function of atmospheric turbulence, the particle diffusion coefficient Dp and the sum of all directed particle motions by thermophoresis, diffusiophoresis, photophoresis, electrophoresis, sedimentation etc. Practically nothing is known about the action of the first three forces and even the easily accessible electrophoresis has not been considered relevant for deposition of atmospheric particles. Because it is relatively easy to change an electric field with all other parameters kept constant and measure the absolute difference in total deposition velocity the following experimental Laser-Doppler study was intended to show the feasibility of the field-changing-technique and the magnitude of the effects without quantitatively determining the electrical mobility distribution as a function of particle size.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/ppsc.19910080104
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    Detection and Chemical Characterization of Polycyclic Aromatic Hydrocarbon aerosols by means of laser-induced fluorescenceDedicated to Professor Kurt Leschonski on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 23-28 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Laser-induced and time-resolved aerosol fluorescence is introduced as an analytical technique for the qualitative and quantitative determination of surface-bound polycyclic aromatic hydrocarbons (PAHs). The analytical figures of merit are evaluated by studying the fluorescent properties (emission wavelengths and temporal behavior) of PAHs adsorbed on submicrometer NaCl particles. In addition to singly adsorbed PAHs on NaCl particles, a three-component PAH adsorbate system is characterized. Detection limits are in the range 5 ng/m3 (e. g. for anthanthrene).
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080106
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  • 63
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    Extended Phase-Doppler System for Characterization of Multiphase FlowsDedicated to Professor Kurt Leschonski on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 16-22 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An extended phase-Doppler anemometry (PDA) system is described, which allows the user to measure the refractive index of spherical particles, in addition to their velocity, diameter and concentration. The extended PDA system incorporates two additional detectors on the receiving side. Each particle generates four Doppler signals. Phase shifts between two pairs of signals are recorded. The ratio between two measured values of phase shifts is a function of the particle refractive index. The phase ratio is shown to be fairly independent of particle velocity or diameter.Calculations based on Mie scattering theory demonstrated the feasibility of the concept. Measurements with monosize droplets of glycerine-water mixture, covering the refractive index range 1.33-1.44, were used to verify the theoretical predictions. The instrument was also tested with spray flows.It is also shown how the phase-Doppler technique may be used to distinguish between reflecting and refracting particles. This means that the extended phase-Doppler system may be employed to recognize particle material, and also to measure locally particle velocities, sizes and concentrations, in a multiphase flow with several transparent dispersed phases and one dispersed phase consisting of reflecting particles.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/ppsc.19910080105
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  • 64
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    Modern Methods of On-Line Size Analysis for Particulate Process StreamsDedicated to Professor Kurt Leschonski on the occasion of his 60th birthdayThis paper was presented at The Engineering Foundation Conference “Control of Particulate Processes”, Matinkyla, Espoo, Finland, August 13-18, 1989. (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 29-34 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two techniques for on-line particle size measurement are evaluated on the reproducibility of their volume distribution determinations. A forward scattering laser light devise is interfaced with a dilutor to examine the potential of this technique for high concentration streams. The forward scattering instruments are capable of outputting extremely reproducible distributions and here we show that when the dilutor is well designed, the on-line instrument can have similar performance. We compare this with a scanning back scatter instrument which is directly inserted in highly concentrated slurries. We present the methods used to improve the robustness of the conversion of the output of the back scatter instrument to volume distributions. The output of the back scatter instrument is inherently less stable but with the proper methods one can obtain reproducibilities of the order of 2 to 6 percent.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080107
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  • 65
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    Particle Size Distribution of Inorganic Colloidal Dispersions: A comparison of different techniques (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 128-135 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The particle size distributions of a latex and of four different inorganic colloidal systems, consisting of spherical particles suspended in aqueous solutions, have been evaluated by three techniques: electron microscopy (EM, scanning and/or transmission), classical light scattering (CLS, polarization ratio method), and photon correlation spectroscopy (PCS, commercial instrument). Both light scattering techniques appear to be exceedingly sensitive to even a relatively small level of aggregation. Thus, the effect of treating the dispersions by ultrasonic energy was tested in order to establish the best experimental conditions. While a shorter sonication results in a minimum or constant value for the average particle diameter (or the polydispersity of the suspension), longer times may promote reaggregation of particles. Good correlation of the results by different light scattering techniques was found as long as the conversion to number averages of the PCS data involved the proper corrections for polydispersity. The agreement with the EM depended on the chemical nature of the dispersed particles; i.e., drying and exposure to the electron beam greatly affected the histograms in some cases.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080124
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    Anomalous Diffraction Effects in the Sizing of solid particles in liquids (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 175-178 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A study has been made of anomalous diffraction effects in the sizing of solid particles in liquids using a Malvern laser diffraction sizer. The particles were N.B.S. standard reference material 1004 glass spheres. The five liquids used were chosen to give a range of refractive index (R.I.) above and below that of the glass; the ratio of solid R.I. to liquid R.I. (m) ranged from 0.92 to 1.15. Measurements were made of the change in the light energy distribution pattern as the value of | m - 1 | was in creased or reduced towards zero. At high values of | m - 1 | the measured light energy distribution pattern was predicted adequately by the Fraunhofer diffraction approximation to Mie theory and the Fraunhofer computer software could be used to derive particle size distribution from the light energy pattern. For values of | m - 1 | near to zero, the Fraunhofer approach was in error but the anomalous diffraction approximation and software proved adequate for the back-calculation of size distribution from energy pattern.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080133
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    Masthead (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140101
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  • 68
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    An improved SRK-equation for the estimation of concentrations by inferential measurements (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 20-28 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method is proposed for solving the vapour-liquid equilibrium problem in binary distillation processes, when pressure and temperature are known. Special attention is paid to the applicability of the method for control purposes. Therefore, a comparison between measured and estimated concentrations is included for the case of propane-propylene distillation. The method is based on an improved Soave-Redlich-Kwong equation of state and is easy to implement on a process computer. It yields a close approximation of experimental vapour and liquid volumes. On applying the original SRK-equation at high pressures, an error in excess of 20% is obtained in the liquid volume which is one of the reasons why this equation cannot be used for control where high accuracy is required. In addition, the conventional mixing rule cannot reproduce the mole fractions correctly. Therefore, a new density-dependent mixing rule is put forward for modelling of experimental results.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140104
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  • 69
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    Adsorption and desorption of halogenated hydrocarbons using activated carbon (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 59-64 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Environmental hazards caused by halogenated hydrocarbons and increasingly stringent regulations for limiting their emission require comprehensive investigations of these substances. The present work deals with the adsorption and desorption of halogenated hydrocarbons on activated carbon. The results could be useful in the utilization of landfill gases because halogenated hydrocarbons must be removed in order to avoid pollution and the loaded activated carbons have to be regenerated. Activated carbons are well suited to removal and recovery of halogenated hydrocarbons from gas flows.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140109
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  • 70
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    Electronic Resource
    Masthead (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140201
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  • 71
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    Studies of drop break-up in liquid-liquid systems in a rotating disc contactor. Part I: Conditions of no mass transfer (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 79-89 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Observations on the break-up of single drops in a rotating disc contactor show that there is a critical rotor speed below which drops of a given size do not break. Weber and Reynolds numbers are required to correlate the data and not simply a Weber number as for turbine agitated systems. The probability of break-up of a drop at the rotor edge is expressed in terms of a Weber number with a lower limit for critical conditions. The mean number of daughter drops produced on break-up is correlated as a simple function of drop diameter based on the critical diameter and agreement is found with data from other types of agitated equipment.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140202
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  • 72
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    A new pneumatic bearing dynamometer for power input measurement in stirred tanks (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 105-108 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A turntable dynamometer has been constructed for the accurate measurement of power input and mixing applications in bench stirred tank reactors. The main feature of this device is a pneumatic bearing with complementary conical parts. The conical pneumatic bearing permitted to apply eccentric loads without affecting its stability. The static friction torque in the pneumatic bearing was very small, 4 × 10-4 Nm, and can be neglected in the experimental ranges of measured torques, i.e. from 5 × 10-3 to 2.21 Nm. In accordance with the instrumentation used, the deviations obtained with the apparatus are less than 10% at low torque readings. At moderate torques, deviations lower than 1% are routinely obtained. Several power input measurements show that the obtained data scatter is lower than 2.5%. The power input response in the turbulent regime is in agreement with dimensional analysis: the power input depends on the cube of the impeller speed. In addition, data obtained with a turbine impeller under ungassed conditions agree with the predictions of a published correlation, which takes into account several geometrical parameters.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140206
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  • 73
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    A new process for indirect gas supply by means of perfluorinated polyethers (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 127-134 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new process has been developed for indirect gas supply for culturing shear sensitive cells by means of a perfluorinated hydrocarbon. Hostinert 216, a perfluorinated polyether, was used as oxygen and carbon dioxide carrier. Hydrodynamics and mass transfer, required for industrial implementation, were investigated in a drop column. Based on the knowledge, obtained with indirect gas supply, it has been possible to construct a waste-gas free sterile pilot plant. Correlations derived from performed measurements permit design of and scale-up to an industrial plant.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140211
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  • 74
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    Electrochemical impedance spectroscopy of oxygen and hydrogen evolution on amorphous alloys in 1 M KOHDedicated to Professor Dr. Dr. hc. Dieter Behrens on the occasion of his 65th birthday (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 263-269 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mechanisms of oxygen and hydrogen evolution on amorphous alloys G 14 (Fe60Co20Si10B10) and G 16 (Co50Ni25Si15B10) in 1 M KOH at T = 298 K and 333 K were studied by electrochemical impedance spectroscopy (EIS). Comparative measurements were carried out on polycrystalline Pt electrodes. Impedance spectra in the frequency range 10-3 Hz ≤ f ≤ 104 Hz were analyzed to determine the kinetic behaviour of amorphous alloys by application of transfer function analysis, using non-linear fit routines. The EIS-data are interpreted in terms of consecutive reaction mechanisms for both oxygen and hydrogen evolution.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140408
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  • 75
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    Masthead (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140501
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  • 76
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    Hydrodynamics, axial mixing and mass transfer in open turbine rotating disc contactor (OTRDC) (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 167-177 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental study of hydrodynamics, axial mixing and mass transfer has been carried out in a newly developed liquid-liquid extraction contactor, namely the open turbine rotating disc contactor (OTRDC). It has been established that the OTRDC can be operated with larger holdups of the dispersed phase, larger interfaces and, hence, more efficient mass transfer than the conventional RDC. In correlating axial mixing data, a combined model has been applied in which both the forward mixing due to drop size distribution and the backmixing of droplets are taken into account. The RTD curves of dispersed phase predicted by the model agree well with the experimental data. Comparison of experimental mass transfer data with those predicted by the proposed axial mixing model and the theoretical single drop model shows that they are in good agreement.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140304
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  • 77
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    Two-phase flow and mass transfer in scrubbersPaper presented by B. Schmidt at the “Jahrestreffen der Verfahrens-Ingenieure”, Berlin, September 27 To 29, 1989. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 162-166 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental investigations were carried out in spray scrubbers of different sizes with cocurrent flow of gas and liquid. Of special interest were the local processes in the mass transfer zone. The scrubber was operated with warm water/air system (cooling tower) to obtain detailed information about mass transfer. Air is being humidified with water vapour, which in turn leads to a temperature drop in the liquid. The liquid temperatures are relatively easy to measure and are shown as liquid isotherms. In the case of plug flow, the liquid isotherms should be straight horizontal lines. In reality, significant deviations from plug flow are caused by the transfer of liquid to the walls. A large part of the liquid forms a film flow at the wall. Furthermore, nearly all the mass transfer is completed in the zone of liquid atomization immediately beneath the nozzle. The number of measured transfer units was between 0.5 and 2.0 and was significantly influenced by the liquid flow rate. Based on the improved knowledge of the proceses inside the scrubber, a simplified model has been developed. Since the model simulates all the essential processes inside the mass transfer zone, liquid distribution and mass transfer efficiency can be approximately predicted.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140303
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  • 78
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    Modelling of selective catalytic denox reactors - strategy for replacing deactivated catalyst elements (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 192-200 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simulation model for denox reactors (high dust) containing honeycomb catalysts and operating at temperatures between 300 and 400 °C has been developed. The model predicts the NOx reduction as a function of process variables (temperature, gas velocity, NOx concentration, NH3/NOx ratio) as well as a function of reactor and catalyst geometry (pitch diameter, length of catalyst layer, number of layers). Model parameters such as the rate constant and the adsorption equilibrium constant of NH3 on the catalyst surface were determined by curve fitting of experimental data obtained in a pilot test unit. Based on model calculations, it is shown that the effect of catalyst poisoning (deactivation) on NOx reduction is not the same for every catalyst layer. The lifetimes of catalyst elements located at the inlet to the reactor appear shorter than those of the elements positioned at the outlet from the reactor. Experimental verification of this theoretical finding is required.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140307
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  • 79
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    Masthead (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140401
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  • 80
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    Operation data of a directly fired absorption heating unit with periodically operating absorberPaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Stuttgart, October 3 to 5, 1990. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 226-233 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This contribution presents the layout, construction, and experimental investigation of operation behaviour of a directly fired absorption heating unit with periodically operating absorber. The working system is CH3OH-LiBr/LiOH. The unit is designed to generate a maximum heat load of 10 kW. The field of application is mainly in domestic heatIng. A special feature of the absorption heating unit is the provision of the major part of required process heat in the heat pump mode of operation with high efficiency. At extremely low ambient air temperatures, heat is supplied in the direct mode. A numerical simulation routine is also described. The simulation program describes both steady-state and dynamic processes in the unit. With models for each component, the performance of individual components can be studied and optimized. The results presented here consist of the first experimentally obtained efficiencies in direct heating mode, results of numerical simulation of the component generator, and a comparison of measured and predicted characteristic system temperatures.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140403
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  • 81
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    Thermally safe operation of a semibatch reactor for liquid-liquid reactions-fast reactions (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 367-375 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Accumulation of the reactant supplied to a cooled semibatch reactor (SBR) will occur if the mass transfer rate across the interface is insufficient to keep pace with the supply rate. Then, due to a low starting temperature or supercooling, the reaction temperature does not rise fast enough to the desired value. This accumulation may eventually lead to a temperature runaway. We investigated the possibility of such an event for reactions of the type “chemically enhanced mass transfer” or “fast” and found that only low distribution coefficients, i.e. 10-4 or lower, can lead to accumulation. At higher distribution coefficients, the mass transfer rate across the interface of a well-mixed dispersion is generally sufficient to prevent accumulation. A thermal runaway in the fast regime exerts a moderate effect, because the effective activation energy is halved. Calculations for the “instantaneous” reaction regime, regarded as a special case of fast reactions, show that there is no runaway possible.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140602
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  • 82
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    Role of sparger design in mechanically agitated gas-liquid reactors. Part II: Liquid phase mixing (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 386-393 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Liquid phase mixing time was measured in 0.57, 1.0 and 1.5 m i.d. mechanically agitated gas-liquid reactors. Transient conductivity technique was used for the mixing time measurement. Pitched blade downflow turbine was employed. The design details of PTD impellers such as diameter (0.22 T to 0.5 T) and blade width (0.25 D to 0.35 D) were studied. The influence of sparger types and their design on mixing time has been investigated. For this purpose, pipe, ring, conical, and concentric ring spargers were employed. The design details of the ring sparger, i.e. ring diameter, number of holes and hole size were also studied in depth. Sparger location with respect to the impeller was found to be the most important variable and, therefore, it was varied for practically all the spargers studied in this work. It was found that the liquid phase mixing time depends on the impeller design, sparger design, sparger location, impeller speed and superficial gas velocity. Correlations have been developed for the dimensionless mixing time.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140605
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  • 83
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    A critical study of multivariable self-tuning algorithms for distillation controlIICT Communication No. 2468. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 399-405 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A control algorithm which has been acclaimed as the best algorithm for a real system may not be the best algorithm for a different real system. Therefore, various self-tuning algorithms for real distillation columns have been evaluated, in order to compare their performances. A variable forgetting factor algorithm is modified using a filter which permits the employment of one instead of two covariance matrices for distillation control. A cautious self-tuning control of SISO system is extended to MIMO system of distillation control. Multivariable self-tuning regulator, multivariable self-tuning controller and multivariable cautious self-tuning controller are implemented with modified variable forgetting factor for linear transfer function model, Waller et al. column, and rigorous non-linear model, Wood and Berry column. For distillation control, a multivariable cautious self-tuning algorithm with modified variable forgetting factor is much simpler than earlier reported algorithms. This has produced better results and demonstrated its effectiveness, even in the presence of noise when other adaptive controllers give unsatisfactory performance.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140607
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  • 84
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    Effect of thermal pretreatment and reduction on acidity and metal state in doped NiH and CuH mordenites (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 428-436 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Thermal pretreatment such as calcination and steaming as well as the reduction of cations by hydrogen, affect the zeolitic acidity and activity of nickel- and copper-doped mordenites in heterogeneously catalyzed reactions such as the conversion of n-hexane. Data on acidity changes were obtained by IR spectroscopy, and information on ionic and metallic states by temperature-programmed reduction, CO chemisorption and transmission electron microscopy (TEM). The findings were compared with reaction results from conversion of n-hexane. Trimethylamine (TMA) was selected as a standardization molecule for semi-quantitative determination of acidity. Correlation of relative acidity values with experimental results was possible only to a very limited extent. Results of CO chemisorption, TPR and TEM allow conclusions to be drawn on metallic crystallites, Ni+ and Cu+ ions and clusters, which appear to exert a stabilizing influence on zeolitic activity. Nickel crystallites with d 〉 2 nm catalyze both hydrogenation and dehydrogenation of paraffins on the metal in bifunctional catalysis, as was also observed on platinum-doped zeolites.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140611
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    Shape Characterization of Crystals and Crystal AgglomeratesDedicated to Professor Kurt Leschonski on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 48-54 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Crystals and crystal agglomerates exhibit a number of specific shape features which evolve in close relation to the conditions of growth and agglomeration. Hence the quantitative evaluation of these shape features by adequately defined shape parameters can serve to obtain a deeper insight into the mechanisms and kinetics of crystal agglomerate formation and to quantify more precisely the quality of crystallization products.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080110
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  • 86
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    Response of Single-Particle Optical Counters to Particles of irregular shapeDedicated to Professor Kurt Leschonski on the occasion of his 60th birthday (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 40-47 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The response of optical particle counters to nonspherical particles is analyzed theoretically and on the basis of experimental results. Theoretical approximations valid for particle diameters d ≪ λ and d ≫ λ (where λ is the wavelength of light) are used to derive some general predictions about the influence of the particle shape on light scattering. These predictions are compared with experiments on six optical particle counters using nonspherical particles. The instruments differ in the kind of illumination (laser or incandescent light), the mean scattering angle and the receiver aperture. When the particle size is smaller than the wavelength the light-scattering diameter of a nonspherical particle comes very close to its volume-equivalent diameter. For irregularly shaped particles larger than the wavelength better conditions than giving a “projected area” response cannot be achieved with an optical arrangement for single-particle detection.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080109
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  • 87
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    Hierarchical Properties of Particle Shape for the recognition of powdered materials (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 116-123 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Particle shape recognition procedures can be used to determine constituent materials. The problem of recognizing the association between the shape and mineralogical composition of a particle, resulting from comminution of a raw ore, is of great interest.An algorithm is presented and computational results are given for the classification of particles of iso-proportional constituents. In this way, the washability function of a set of particulate raw ores can be estimated by taking into account only the contour of the particles. This classification procedure is useful when there are difficulties in the estimation of some relevant properties such as specific gravity or magnetic susceptibility.The procedure has been successfully applied to the recognition of the mineralogical composition of particles resulting from the comminution of a chromite ore and to the classification of particles in iso-composition classes.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080122
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    A Re-Examination of Piper's Shape Analysis Technique (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 110-115 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An image shape analysis technique which measured the angles between adjacent vectors on the image edge was previously proposed by Piper, but the accompanying data was scant. This method is shown to have great promise when applied to several images obtained using a video camera with a computer. Better data representation is obtained using a single plot of the average measured angle at each step length versus the step length. Both scale and degree of maximum roughness are immediately evident on this plot. The measured angles may be corrected to remove image circularity effects from the angles, in which case some macroscopic shape effect is also described by the plot. Similarity with the Richardson (fractal dimension) plot is discussed.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080121
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  • 89
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    Electronic Resource
    Using Sierpinski Fractals to Characterize Changes in the Cytomorphology of hepatopancreatic b-cells of porcellio scaber latreille (fam: Porcellionidae, crustacea) reared on different diets (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 124-127 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sierpinski fractal dimension analysis is used to describe the cytomorphology of hepatopancreatic large B-cell of a terrestrial isopod, Porcellio scaber Latreille (Fam.: Porcellionidae, Crustacea). Isopods were starved for six weeks, and then re-fed for two days on diets containing glucose and butter. The cytomorphological changes undergone by hepatopancreatic B-cells after starvation and re-feeding periods are characterized by their fractal dimensions. The significance of these findings is discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080123
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  • 90
    Electronic Resource
    Electronic Resource
    Particle Sizing by Photon Correlation Spectroscopy. Part II: Average values (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 187-193 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The average values of the diameters and the diffusion coefficients of non-interacting homogeneous spherical particles as obtained with photon correlation spectroscopy are reviewed. In general, the average diffusion coefficients calculated from the first cumulant can be identified as intensity averages, while the average particle diameters are harmonic intensity averages. For particles with linear dimensions that are small compared to the wavelength of light, the intensity averages can be identified as z-averages for the diffusion coefficient and as harmonic z-averages for the diameter. For larger particles the intensity averages are, however, different from the z-averages and are dependent on the material examined (relative refractive index) and on the experimental equipment used (laser wavelength and state of polarization and scattering angle).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080135
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  • 91
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    Electronic Resource
    Sedimentation of Nonspherical Particles (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 209-214 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The motion of real oblate particles of different cross-section can be described with sufficient accuracy by equation valid for spheroids. The proof was effected by means of velocity measurements.The application of theoretical considerations to sedimentation analysis allows it to be used to calculate apparent distributions occurring in the sedimentation of monodisperse particles of uniform shape at any orientation relative to the direction of sedimentation. The transfer to polydisperse systems involves several difficulties, which can be avoided in part by suitable approximations. In the case of a particle system with a polydisperse distribution of a main axis, but a constant particle shape, it is possible to calculate the resulting apparent distributions and their deviations from those distributions obtained when applying the volume equivalent particle diameter.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080138
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  • 92
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    Electronic Resource
    A technique for measuring contact angles at particles (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 215-221 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The behavior of particles at the phase transition between a gas or liquid and another liquid phase may be characterized by the so-called wetting (or contact) angle. In contrast to plane surfaces, which allow such measurements to be conducted relatively easily, the determination of the wetting angle between a liquid and the surfaces of fine particles demands extensive preparative measures. The method adopted by Heertjes and Kossen [12] for example, involves compressing a tablet from the powder in question, from which the wetting angle may then be derived. The compression process naturally modifies the superficial structure of the particles, and hence their wetting characteristics. This paper describes a preparation technique with which the wetting angle between a liquid and fine particles can be derived without modifying the surface texture. This involves coating and adhering a monolayer of the powder on a carrier plate and measuring the composite wetting angle of the particles and the adhesive film. The specification of the adhesive's wetting angle and areal porosity of the carrier medium allows the wetting angle of the given powder subsequently to be evaluated.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080139
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  • 93
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    Electronic Resource
    Characterization of BCG Vaccine by coulter counter and scanning electron microscopic techniques (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 194-199 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: BCG vaccine, an important immune stimulant used in cancer therapy, consists of a suspension of living and dead cells, cellular fragments and aggregated cells. For this reason, nephelometric methods are unable to determine the total numbers of cells in a vaccine system. Scanning electron microscopy has enabled average cell dimensions to be obtained of length 2.36 μm, width 0.47 μm (n = 1,227), equivalent to a spherical particle of volume 0.3887 μm3 and diameter 0.9055 μm. Measurement of the particle size of a diluted vaccine with a Coulter Multisizer, fitted with a 50 μm diameter orifice, enabled the total number and average size of aggregated cells to be determined. Multiplying the total number by the number of cells in an average aggregate (obtained by dividing the volume of the average aggregate by the average cellular volume) provided a direct estimate of the total number of cells in the system. The total wet weight of cells present in a vaccine ampoule can be estimated by measuring the methylated esters of palmitic acid (PAME) in the system using gas chromatography. This weight, divided by the weight of an average cell, provided an independent confirmation of the total number of organisms present. In order to obtain the cellular density a Percoll gradient sedimentation was carried out. Surprisingly the organisms separated into two fractions of closely similar density, an average value of 1.070 g/mL being obtained. The two fractions had different average sizes with different distribution functions.When data for a number of lots of TiceTM substrain prepared over a twenty-two year period were compared, the correlation between the Coulter and PAME methods was seen to be relatively good, bearing in mind the intrinsic variability of biological systems. Comparison with viability (colony-forming unit) measurements demonstrated a loss in viability with time after preparation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080136
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  • 94
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    Electronic Resource
    Light Scattering Applied to LDA and PDA Measurements. Part 1: Theory and numerical treatments (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 245-258 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mathematical tools are provided for computation of the scattered field produced by a spherical particle moving through the region of interference of two crossing laser beams. This formulation is readily applicable to laser Doppler and phase Doppler anemometers (PDAs). In particular, the geometry of PDAs is treated in the most general terms. The cases of very large and very small particles are considered in detail. In the first part the theory underlying the computer code STREU, which was produced during the present work, is discussed and relevant mathematical formulations are presented. Also, graphical tools are provided for the convenience of the designers.In Part 2 the utility of the computer code is demonstrated with the help of examples in the area of phase Doppler anemometry. It is shown that the phase Doppler technique may be used for sizing of submicron particles in addition to large particles. Measurement of particle refractive index, in addition to the diameter, is also made possible.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080147
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  • 95
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    Electronic Resource
    Measurement of the Refractive Index of Atomised Liquid Drops by light scattering (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 267-273 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is demonstrated that the complex refractive index of liquid drops in a spray can be measured using the LDA visibility technique and averaging over a number of particles. A minimum of five scattering angles was required. One of these, close to the forward direction, monitored the particle size. It was estimated that the real part of the refractive index could be measured to within about ± 0.01 and the imaginary part to within ± 0.0004.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080149
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  • 96
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    Announcement (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 323-324 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080159
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  • 97
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    Electronic Resource
    An Algorithm for Determination of the Size-Dependent breakage frequency of droplets, flocs and aggregates (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 315-322 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method, based on the use of discrete size classes, is developed to extract size dependent breakage frequencies from sequential measurements of the size distribution. In order to obtain good resolution and allow for several breakage modes, interlaced Fibonacci series are used to define the size classes. Both binary and ternary breakage are considered. An approach based on Kernel Discriminant Analysis is used to focus the breakage at the discrete size classes. The algorithm is tested using simulated distribution data. The sensitivity of the retrieved breakage frequencies to the assumed progeny distribution and to the number of breakage events between samples is considered. The numerical experiments show that the method is effective even when the breakage mechanism is not well understood.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080157
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  • 98
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    Electronic Resource
    Fluid mechanics of circulating fluidized beds (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 29-38 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A fluid mechanical model of segregated vertical gas-solids flow has been developed. Mass and force balances were set up with the aid of this model and, finally, a dimensionless state and pressure drop diagram was calculated. In this diagram, the pressure gradient caused by the solids transport is plotted in dimensionaless form versus the superficial gas velocity in the form of a particle Froude number. Parameter is the ratio of the solids volumetric flow rate at minimum fluidization to the gas volumetric flow rate. The state and pressure drop diagram is valid for a given gas-solids system, i.e. for a given Archimedes number and given minimum fluidization porosity. The fluid mechanical behaviour of different types of circulating fluidized beds can be explained with the aid of the state and pressure drop diagram for segregated vertical gas-solids flow. As an example, the operating behaviour of circulating fluidized bed with a syphon in the solids downcomer is discussed. Measurements of the circulating solids mass flow rates are compared with calculation results.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140105
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  • 99
    Electronic Resource
    Electronic Resource
    Apparatus for steady-state kinetic measurements of the catalytic reduction of nitric oxide by ammonia on iron oxide (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 39-44 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The reduction of nitric oxide with ammonia on an unsupported iron oxide catalyst has been studied in a continuous-flow recycle reactor using simulated flue gas. The responses of the employed reactor system to step and pulse inputs of tracer indicate that the system could be regarded as a continuous stirred tank reactor (CSTR). Preliminary tests were carried out to determine the effect of temperature and particle size on the measured reaction rates. Additional experiments were performed in order to study the influence of oxygen and water concentration on these rates. A gas chromatographic system has been developed to analyze the gas components NO, N2O, NO2, NH3, H2O, O2, CO2 and N2. In addition, the concentrations of NO and NO2 were measured with a nondisperse infrared (NDUV/NDIR) analyzer.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140106
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  • 100
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    Electronic Resource
    Cooling of arc furnace electrodes with heat pipesPaper presented by K.-G. Bullerschen at the meeting of the “GVC-Fachusschuß Hochtemperaturtechnik”, Köln, January 19 to 20, 1989. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 45-53 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Combination electrodes with water cooling shanks, which have been introduced to reduce graphite consumption in UHP furnaces, cause the danger of vapour explosions in case of breakIng. Heat pipes are highly efficient two phase heat conductors which could provide a safer alternative to water cooling shanks, since they contain only a small amount of liquid. The transport of energy results from evaporation of the working fluid in the heated section, convection of the vapour to the cooled section and reflux of the condensed fluid to the heated end. Large heat quantities can be transferred under nearly isothermal conditions within the tube, as long as certain limits are not exceeded. The operating temperature can be controlled by design parameters such as the thermal resistance of the cooling zone. The proper function of heat pipes for cooling arc furnace electrodes is investigated by comparing the calculated heat load with temperature dependent limits to heat transport. It is shown that copper tubes with water as the working fluid combine efficient cooling and safe performance in the low temperature range, while the cheaper steel tubes with sodium filling are suitable for high temperature operation.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140107
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