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  • 1995-1999
  • 1985-1989  (52)
  • 1970-1974  (410)
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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987) 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 33-37 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: All the present experiments confirm that there is some liquid channelling on trays. Liquid channelling is extensive on trays of large diameters. It largely depends on the tilting of the plate, modifications of the inlet weirs and on non-uniform bubble cap spacing. Consequences of liquid channelling for plate efficiency are clear; the higher the degree of liquid channelling the lower the plate efficiency. However, own experimental and theoretical investigations indicate that plate efficiency never falls below the value of point efficiency. Therefore, liquid channelling only affects the crossflow on trays. Liquid channelling reduces the mass transfer performance to a similar extent as does the backmixing of liquid. Consequently, plate efficiency is not very sensitive to liquid channelling. Since the liquid is completely mixed in the downcomer, the effects of liquid channelling are restricted to a single tray. The behaviour of tray columns completely differs from that of packed columns, where the effects of liquid channelling are cumulative over the packed height. Consequently, trays represent a suitable design for columns of large diameters.
    Additional Material: 10 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 16-27 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Although carbon dixoide is important as an abundant carbonaceous raw material, so far, its utilization in chemical processes has been rather limited. This review covers the reactions of CO2 employed in industry, such as the production of urea, the Kolbe-Schmitt reaction, the synthesis of cyclic organic carbonates and the use of CO2 in methanol synthesis. Interesting recent developments in CO2 chemistry, such as the reactions catalyzed by transition metals, are also described. Apart from the synthesis of polymers and hydrocarbons, the production of oxygen-containing substances appears to be very profitable and attractive for future industrial applications. Not only can derivatives of formic and carbonic acids be produced but also longer-chain carboxylic acids and their derivatives by reactions of carbon dioxide with hydrocarbons such as alkynes, alkenes and 1,3-dienes.
    Additional Material: 5 Ill.
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  • 4
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The present contribution illustrates a way of developing a continuous separation process for near critical fluid extraction, on the example of separation of soya oil from lecithin. First, a suitable solvent was selected. Phase equilibria were measured in autoclaves. Operating conditions for a pilot plant were derived from the phase equilibrium data. The pilot plant experiments provided the necessary data for designing a production plant. Computer programs for phase equilibrium, stage to stage and mass and heat balance calculations were used in order to minimize the number of experiments. A production plant with a capacity of 500 t/a of raw lecithin was designed on the basis of experimental and computational results. A cost estimation, based on tenders, showed that it is more economical to produce lecithin by near critical fluid extraction than by conventional acetone extraction.
    Additional Material: 7 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 56-63 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ideal flow conditions are generally assumed for the reactor design. If stoichiometry, reaction mechanism and kinetics are known, the balance equations for the ideal flow tube, the ideal steady-state continuous stirred tank reactor or the ideal, completely mixed stirred batch reactor are often applied. In many cases, formal kinetics, which forms the basis of reaction modelling, is so uncertain that the idealization of the flow field can be accepted. In practice, however, deviations from the ideally calculated conversions, yields and product qualities, often occur. In these cases, it is necessary to consider the real flow conditions. In general, a distinction is made between macroand micromixing processes.
    Additional Material: 9 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 1-15 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Using pilot-scale test plant, the interfacial area per unit volume was investigated in different gasliquid reactors, i.e. packed column, bubble column and free jet reactor. The interfacial area was studied as a function of liquid viscosity and of operating parameters. As a rule, identical test conditions were maintained in all the measurements, in order to obtain comparable results. The interfacial area was determined by chemical means using the sulphite system (a solution of sodium sulphite in water as model liquid and air as gaseous medium). The viscosity of the solution can be increased by adding carboxymethyl cellulose without significantly affecting the reaction kinetics. The addition of a surfactant to the sulphite system allowed comparative measurements at reduced surface tension. Based on a large number of measurements, the correlations of the interfacial area are expressed as power laws. The inclusion of experiments with a jet tube reactor and a stirring vessel allows an extensive comparison of all reactors. All tests were carried out with the same material system and the same method was used to determine the interfacial area per unit volume. Therefore, a comparison with respect to mass transfer is possible.
    Additional Material: 21 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 27-32 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new measurement method for determining the local liquid-phase velocities in multiphase flows is presented. It is based on a tracer technique, using heat introduced into the flow, seemingly at random, instead of a material tracer. The input of heat pulses and measurement of temperature at an adjacent point is performed by small probes. As an intermediate result, the flow time distribution of the heat-labelled fluid elements is calculated on-line as a cross-correlation function between the pseudo-random input and the measured output signals. This calculation and the automatic control of measurements is carried out by a simple microprocessor unit. The device produced excellent results in gas-liquid flows at high gas throughputs and high liquid-phase velocities.
    Additional Material: 6 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 63-72 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Among other processes, adsorption is used for the removal of hydrogen sulphide from natural gases. Hereby, competitive adsorption of the different gas components plays an important role, e.g., that of carbon dioxide. Data of equilibrium loading and adsorption kinetics are required for the design of adsorbers, filled with molecular sieve. In order to obtain these data under the prevailing operating conditions, hydrogen sulphide was removed from gas mixtures H2S/CH4 and H2S/CO2/CH4, in a pilot plant, by adsorption on molecular sieve 5A. The equilibrium loading, the height of transfer zone, and the length of unused bed were determined from the measured breakthrough curves of H2S. With these data, the breakthrough time and the optimum process conditions were calculated for a practical example.
    Additional Material: 14 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 43-55 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The oxidation of carbon monoxide by air in a turbulent flow was investigated under experimental conditions where the rates of turbulent mixing and of chemical reaction are comparable. For this purpose, carbon monoxide was admixed into the completely burnt gas of a natural gas flame operated with excess of air. Measurements of mean values of axial velocity, temperature and volume fractions of carbon monoxide and oxygen were compared with computational simulations involving the k - ∊ turbulence model and several turbulent reaction models for the oxidation of carbon monoxide. The comparison of measurements and numerical calculations demonstrated that the k - ∊ turbulence model is suitable for prediction of the turbulent flow field in the flow system investigated. Furthermore, it could be shown that one-variable turbulent reaction models, such as the flamesheet or the eddy-break-up model, cannot explain the measured carbon monoxide volume fraction profiles. Two-variable turbulent reaction models with a probability density function closure of the source term of the transport equation for the mass fraction of the chemical species result in a better agreement between the measured and simulated volume fraction profiles, particularly in predicting the clear influence of the initial temperature on carbon monoxide volume fractions. Weighting of the kinetic rate expression for the oxidation of carbon monoxide with different presumed probability density functions yields slightly different predictions of the carbon monoxide volume fractions, reflecting the assumed different character of turbulent fluctuations.
    Additional Material: 7 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 92-98 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Distillation columns with vertical partitions can separate a feed mixture into 3 or 4 pure fractions. Compared to other column arrangements, their investment costs and energy consumption are lower. Production columns show good results and are easily controlled. Conventional distillation columns produce only 2 pure product streams at the top and at the bottom of the column. Side products are contaminated by light or heavy components, depending on the location of the side stream in the rectifying or stripping section. This disadvantage is set aside by using a distillation column with a vertical partition. The internal separation wall prevents lateral mixing of liquid and vapour in the central part of the column, forming there separate feed and outlet sections. In the presence of a vertical partition, 3 or 4 pure fractions can be obtained in a single distillation step. This is particularly advantageous when heat sensitive components are to be separated. On account of good thermodynamic properties, the energy consumption is 20 to 35% lower than that of other distillation arrangements. The control behaviour is similar or better than that of conventional distillation columns.
    Additional Material: 11 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 86-92 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Carman-Arnell equation relates the rate of flow of a fluid through a packed bed to the pressure drop across the bed. This equation is the basis for surface area determination by permeametry. It is found that the surface area measured at sub-atmospheric pressure varies with the bed porosity, so a porosity was selected where the rate of change was at a minimum. The study suggests that, at reduced pressures, the gas flow rate is a linear function of the mean pressure.
    Additional Material: 3 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 104-112 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A 0.5 MW spray-dry scrubbing FGD pilot plant was used in the study of spray dryer performance over a wide range of operating conditions. Experimental findings were compared with a spray dryer model. During operation with large excesses of lime, the SO2 absorption was limited by gas phase diffusion. At operation with a shortage of lime, the rate limiting step was the dissolution rate of lime. In addition, the flow regime in a spray dryer can be best described as well mixed. The SO2 level in the flue gas was found to exert no direct effect on the efficiency of SO2 removal. The observed effects are attributed solely to the changes in the drying process, due to the inter-dependence of slurry composition and SO2 concentration.
    Additional Material: 9 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 73-86 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: As a part of a research project on the mass transfer in liquid pulsed sieve-tray extraction columns (PSE), the diameters and hold-ups of the drops were measured: the drop size using a suction technique, with photoelectric detection, which was adapted to the special boundary conditions of the PSE; the integral hold-up by the pressure difference between the lower and upper parts of the column. Since experimental results cannot be described by known calculation formulae for the Sauter mean diameter and the hold-up, a new method of calculation was developed. It is phenomenologically based on high-speed photographs of the drop motion on a sieve tray. The mathematical-physical model allows the prediction of drop size and hold-up within certain limits, while the possible different operating regimes of the PSE, i.e. the mixer-settler and dispersion regimes can also be estimated.
    Additional Material: 12 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 125-131 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When crude oil is vacuum distilled, about 30% of the feed remain as low value residue. Hydrocracking can upgrade this residue into valuable light hydrocarbons. The hydrocracking could be optimized catalytically, if the residue were not to contain the metals vanadium and nickel that poison the catalyst. This contribution shows that continuous extraction of the residue with ethyl acetate yields a fraction with low metal content, while an asphaltene fraction with the remaining metal content is filtered off.
    Additional Material: 14 Ill.
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  • 15
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A one-stage model of the formation of primary bubbles is presented in which the bubble volume is deduced from an equilibrium of buoyancy, viscosity, inertia and surface tension forces. In contrast to the two-stage model, presented by Kumar and Kuloor, it was not assumed that the drag coefficient in bubble expansion can be described by the same constants as in the steady-state bubble ascent. The constants were adapted in such a way that the introduction of an additional bubble volume was not necessary. It was demonstrated that this model describes the bubble formation in gravitational and centrifugal fields equally well and, furthermore, is also applicable to structurally viscous liquids, provided that the effective shear gradient \documentclass{article}\pagestyle{empty}\begin{document}$$ \mathop {\rm \gamma }\limits^. = \frac{1}{6}({\rm \Delta \rho }gzd_{\rm B} /{\rm \eta }) $$\end{document} is calculated from the equilibrium of shearing and buoyancy forces. The model is based on the assumption of a constant volumetric flow rate during bubble formation and, for this reason, a minimum Froude number is necessary in analogy to the weeping limit for sieve plates. The normalized presentation permits simple operation. The possibility of applying the model to drop formation was confirmed by comparison of experimental values with those, predicted by the model.
    Additional Material: 9 Ill.
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  • 16
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new equipment for the measurement of virial coefficients of pure substances and binary mixtures is described. It consists of an improved modification of the set-up proposed by Eucken and Meyer in 1929. The development is based on a critical review of the existing methods particularly with respect to adsorption effects. In order to reduce the influence of adsorption on the accuracy of virial coefficients, an optimum range for gas density is recommended. The accuracy of the virial coefficients is better than 20 cm3 mol-1. The set-up was employed for the measurement of virial coefficients of acetone and hexane in the range from 352.95 to 393.85 K. The results are in excellent agreement with data published in literature. Furthermore, cross-virial coefficients of the binary system acetone/hexane were measured and interpreted.
    Additional Material: 13 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 113-125 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fouling and/or scaling of heat transfer surfaces causes serious problems in industry. Prevention of fouling is therefore essential for technical (considerable deterioration of heat transfer) and also economic reasons (increased costs). In order to provide successful countermeasures, it is, however, necessary to obtain more detailed information on the physical, chemical and biological processes which produce fouling. Based on the already known fouling mechanisms, it is shown that a satisfactory prediction of fouling behaviour of heat exchangers is not yet possible. This contribution presents a physical model for the description of fouling, caused by sedimentation and crystallization. It is assumed that, during fouling, deposition and removal processes overlap. In order to verify the theoretical considerations, experiments were carried out on a test rig, which could also be used for field experiments. Aqueous CaSO4 solutions served as experimental liquids. A comparison of experimental and calculated fouling factors shows a satisfactory agreement.
    Additional Material: 23 Ill.
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  • 18
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 157-164 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Based on a paper by Hein, a dimensioning program for tube-bundle heat exchangers with straight tubes and fixed tube sheets has been developed. The equipment to be dimensioned is tested at 14 critical points, with regard to permissible stresses. The optimum thickness of the tube sheet, the shell and channel are subsequently selected on the basis of economic criteria. Compared to dimensioning according to AD-data sheet, it is possible to save between 10 and 25% of production costs. With the aid of a finite-element (FE) program, complex structures such as heat exchangers can be calculated accurately. Several mesh-generation programs were written for the data input. The structure of a tube-bundle heat exchanger with straight tubes is generated with 3/D elements with only some geometrical data. An FE-calculation of a heat exchanger is explained with the aid of an example and stress analysis is presented.
    Additional Material: 19 Ill.
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  • 19
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The present contribution reports on a new method for the simulation of the dispersed phase behaviour in liquid-liquid extraction columns. The fluid dynamic description is based on a mathematical model which explicitly takes into account drop transport, break-up and coalescence mechanisms, via a drop population balance along the column. Application of the model requires some simple measurements on single drops in order to determine transport and break-up laws, which are required by the model, and possibly also coalescence parameters. In this study the model is applied to pulsed sieve plate columns. The specific example considered here is based on systematic studies on the determination of break-up rates from the corresponding probabilities of break-up and the generated daughter drop size distributions by means of high-speed photography. The validity of the model was subsequently tested by comparison with some experimental results from studies on two different pulsed columns 80 and 225 mm in diameter for the water/toluene system without mass transfer. The satisfactory agreement between the results justifies the use of such a method for the description of the behaviour of liquid-liquid extraction columns in a wide range of operating conditions. Furthermore, application of the model may help to dispense with long and expensive pilot tests.
    Additional Material: 12 Ill.
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  • 20
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microbial desulphurization of coal by pyrite oxidizing enrichment cultures containing predominantly Thiobacillus ferrooxidans was performed in an air-agitated slurry reactor, 20 l in volume. A model of microbiological and chemical reactions, occurring at various points within the coal, was set up taking into account the pore structure of the coal. The influence of parameters relevant to industrial processes, such as superficial gas velocity, particle size, initial pyrite concentration, and slurry density of the coal, on the conversion of pyrite was examined. Variation of the superficial gas velocity in the range of 0.01 to 0.04 m/s confirmed that the reaction is not controlled by oxygen transfer from gaseous to liquid phase. The rate of pyrite oxidation depends mainly on the accessibility of pyrite to micro-organisms which is determined by the particle size of the coal as well as the distribution of pyrite crystals in the coal matrix. The accessibility of pyrite to the micro-organisms is described by the ratio of effective to maximum microbial activity, measured as oxygen consumption. Starting with higher initial concentration of pyrite in the coal increases the oxidation rate, according to first order kinetics. Enhanced slurry densities lead to a decrease of pyrite conversion, in spite of higher pyrite concentration. The maximum pyrite oxidation rate was measured at 15% (v/v) slurry density and 25°C as 1800 mg Spyr/kg coal per day, or 360 mg Spyr/l reactor volume per day.
    Additional Material: 13 Ill.
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  • 21
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 131-142 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of electrolytes, which are dissolved in the aqueous absorbent and do not react with nitrogen oxides, on the absorption kinetics of both these components was investigated experimentally. In addition to demineralized water, various salt solutions of different concentrations as well as sodium hydroxide solution were used as absorbents. The term H \documentclass{article}\pagestyle{empty}\begin{document}$ H\sqrt {k_1 D} $\end{document} for N2O4 and N2O3, which is important for the design of industrial absorbers, was determined as a function of composition and concentration of the absorbents. In the case of N2O4, the chosen measuring and evaluation methods permitted a separate determination of the rate constant k of the pseudo first order reaction and of the solubility H. The diffusion coefficient D of the gas in the absorbent can be obtained only by calculation. Experimental results showed that \documentclass{article}\pagestyle{empty}\begin{document}$(H\sqrt {k_1 D} )\,_{{\rm N}_{\rm 2} {\rm O}_{\rm 4} } $\end{document} decreases with increasing ionic strength I, however, without a clear indication of any ion-specific effects. This decrease does not appear to be caused simply by a reduction in solubility (salting out effect), or in diffusion coefficient, but at least, to the same extent, through a decrease of the rate constant k with increasing electrolyte content in the absorbent. The measurements permitted the determination of the gas-based salting out parameter for N2O4. The investigations on the absorption of N2O3 in water and in an Na2SO4 solution showed no experimentally detectable influence of dissolved salts on \documentclass{article}\pagestyle{empty}\begin{document}$(H\sqrt {k_1 D} )\,_{{\rm N}_{\rm 2} {\rm O}_{\rm 3} } $\end{document}. The numerical value of \documentclass{article}\pagestyle{empty}\begin{document}$(H\sqrt {k_1 D} )\,_{{\rm N}_{\rm 2} {\rm O}_{\rm 3} } $\end{document} is six times that of \documentclass{article}\pagestyle{empty}\begin{document}$(H\sqrt {k_1 D} )\,_{{\rm N}_{\rm 2} {\rm O}_{\rm 4} } $\end{document}.
    Additional Material: 12 Ill.
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  • 22
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Slurry bubble columns are widely used in biotechnology. Therefore, the effects of solid particles on fluidization characteristics, gas hold-up and volumetric liquid-side mass transfer coefficient were measured in a slurry bubble column (i.d. 0.14 m). The density and diameter of the suspended particles were similar to those applied in biotechnology with immobilized bacteria. Based on models of turbulence and of liquid circulation induced by rising gas bubbles, equations for critical gas velocity, gas hold-up and volumetric liquid-side mass transfer coefficient were obtained by dimensional analysis.
    Additional Material: 13 Ill.
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  • 23
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The detailed dynamic simulation of coupled process units in chemical plants is gaining an increasing importance as a useful tool in plant engineering and operation. The outline of the program package DIVA (Dynamische Simulation verfahrenstechnischer Anlagen) which is currently under development is presented in the following. The dynamic plant equations and the corresponding Jacobian matrix are generated automatically. The full exploitation of sparse matrix techniques in combination with stiff ODE (ordinary differential equation) solvers allows an efficient solution of all the equations simultaneously. The possibilities offered by the simulator are demonstrated by the simulation of two laboratory plants.
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  • 24
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 190-203 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Spatially resolved oxygen concentration measurements were performed in premixed hydrocarbon flames by using laser induced spontaneous Raman scattering. The measurements demonstrate the performance of a relatively simple pulsed laser Raman probe for fundamental combustion studies and also for the control of the equivalence ratio in flames (best spatial resolution: 0.2 mm3; theoretical detection limit: 0.8% of O2). Comparison of the results with those obtained by a mechanical suction probe (Magnos 2 T) confirmed a good agreement. At present, control of different stoichiometric conditions is possible at a minimum O2 concentration of 1.3%.
    Additional Material: 25 Ill.
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  • 25
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: During the sudden unheated vessel top venting of initially saturated two-component gas/liquid mixtures, in which the gas is also extensively dissolved in the non-evaporating liquid phase, a solubility inequilibrium develops between the phases; re-equilibration can set in only after a so-called desorption delay time. Laboratory measurements of this delay time were under-taken with model mixtures of CO2 and water and viscous aqueous (Newtonian) solutions by high speed cinematography. The parameters of the experiments are relief cross-section, initial liquid level, pressure, temperature, and concentration. The shortest deley time obtained lasts approximately 75 ms. It differs substantially from the minimum boiling delay time previously measured with various refrigerants in the same test facility. The experimental results are correlated by a semi-empirical dimensionless power relationship, which includes all independent primary design variables generally availble in a physically consistent interrelationship. Reasonable extrapolations to other test conditions and aqueous two-component systems with an acceptable accuracy systems can therefore be expected.
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  • 26
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Correlations for pressure drop and upper capacity limit (flooding) are useful for the design of packed columns. Available correlations are based on the results of measurements made at atmospheric pressure. Extrapolation to higher pressures is not recommended. Therefore, systematic experimental investigations were carried out in a pilot plant at pressures of up to 100 bar. The experimental equipment and techniques, evaluation methods, and some characteristic experimental results are presented.
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  • 27
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 224-230 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper describes a pilot plant for entrainment measurements on various types of column trays. The data obtained from different trays differ by up to a factor of 10. The measurements were compared with the theoretical model of Stichlmair. The Stichlmair entrainment diagram permits a fairly accurate prediction for most types of trays if the height of the two-phase layer is known. Prediction of the height and relative liquid hold-up in this two-phase system should be modified by a term reflecting the vapour flow profile, which requires further testing. These tests should examine the effect of tray spacing, fractional free area and, in particular, the influence of different media.
    Additional Material: 9 Ill.
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  • 28
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 204-215 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In three-phase systems, where the liquid constitutes the continuous phase, solid is the catalyst and gas represents the dispersed phase, there are decisive criteria which have to be observed in reactor design. These are e.g. the interfacial area per unit volume between gas and liquid, the volumetric mass transfer coefficient and the mass transfer coefficient. The basic aim of the present work was therefore the investigation of these parameters in relation to the main influencing parameters. Process parameters stirrer speed and superficial gas velocity were varied as well as the physical properties such as liquid viscosity, solids concentration, particle diameter and a geometrical parameter, i.e. reactor diameter. The sulphite method was employed for the determination of these values. The test results confirmed the known relationships of power consumption and superficial gas velocity. An increase in the liquid viscosity leads to a decrease in all the tested values. In most cases, suspended solid particles lead to a lowering of the test values. The influence of the tank diameter on the plots of the test values against specific power consumption turned out to be invariant so that a scale-up of geometrically similar systems can be carried out at constant power consumption, superficial gas velocity and liquid viscosity.
    Additional Material: 27 Ill.
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  • 29
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    Chemical Engineering & Technology - CET 10 (1987), S. 242-248 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pool boiling data of multicomponent mixtures show that the heat transfer coefficients can be considerably lower than those of a corresponding pure fluid with the same physical properties as the mixture. The proposed model, which assumes maximum mass transfer resistance in the liquid boundary layer, is confirmed by the comparison between calculated and experimental data. The model allows the prediction of heat transfer coefficients in pool boiling of mixtures using only single component properties and vapour-liquid equilibrium data. Judging by experience with a number of different systems, the method should be sufficiently accurate for most practical applications.
    Additional Material: 10 Ill.
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  • 30
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 248-255 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The development of heat resistant permeation membranes has opened up new possibilities for the conversion of fossil energy resources. In steam reforming of natural gas, such membranes even permit a direct production of hydrogen at high temperatures during the conversion of feed hydrocarbons. Further gas processing, such as required for reformer gas in existing hydrogen production processes, is not necessary. Due to continuous hydrogen discharge directly in the reformer tube, the chemical equilibrium of the occurring reactions becomes displaced towards the products, resulting in more favourable process conditions and, consequently, in improved by 36% utilization of the feed hydrocarbons. At the same time, the hydrogen yield increases by 44%. The heat required, which is provided by a high temperature reactor, is 17% in excess of that in conventional plants. It can be expected that the simplified process design will produce substantial cost advantages over the existing processes for the production of hydrogen.
    Additional Material: 14 Ill.
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  • 31
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the present paper, models are developed for the description of coalescence and splitting of bubbles in gas fluidized beds. The distinction between slow and fast bubbles, which originates from the Davidson model of gas flow in and around a rising bubble, was found to be decisive for the modelling of coalescence processes. On the basis of the respective models, it is shown that a change in bed temperature does influence the mechanisms of both bubble coalescence and splitting. In cases of both slow and fast bubbles undergoing splitting, the theory predicts a decrease of bubble size with temperature whereas in the case of a non-splitting system with fast bubbles, typically encountered with Geldart type B particles, no significant temperature effect on bubble size is expected. The theoretical predictions are shown to be in agreement with own measurements as well as with the results of other workers.
    Additional Material: 15 Ill.
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  • 32
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 262-271 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pressure pulsations in hydraulic systems, generated by reciprocating pumps, can cause serious problems with regard to plant safety and reliability. In particular, fatigue problems arise in high-pressure piping systems. The available knowledge is not sufficient for an accurate computation of pressure peaks in the piping of reciprocating pumps. A number of calculation models are available which, however, neglect both fluid compressibility and friction. This contribution presents a calculation method which allows a precise modelling of various pump installations. Comparison of calculated and experimental data shows a good agreement and provides a validation of the computational model.
    Additional Material: 18 Ill.
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  • 33
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    Chemical Engineering & Technology - CET 10 (1987), S. 256-261 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the separation of gaseous mixtures by gas permeation, it is in some cases impossible to achieve the desired product quality in a single stage and, therefore, several stages may be necessary. Multistage processes can be implemented by membrane modules arranged in the form of a cascade or by a membrane column design. On the basis of an economic analysis, this paper discusses different possible module arrangements for 2 cases, i.e. the enrichment of oxygen from air and the separation of methane from biogas. Present calculations indicate that, in the first case, two-stage cascades with or without recycle and, in the second case, one-stage cascade without recycle constitute the optimum module arrangements. However, depending on the selling price of the methane enriched gas, one- or two-stage cascades with recycle have to be considered. Finally, It was shown that, in the permeation of non-ideal gases, the Joule-Thomson effect has to be taken into account.
    Additional Material: 10 Ill.
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  • 34
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    Chemical Engineering & Technology - CET 10 (1987), S. 281-289 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fundamental investigations of coalescence processes in settlers with plate packages for the separation of liquid-liquid dispersions prompted an analysis of the drop motion on the interface of a stratified two-phase flow. Therefore, a physical model was developed, which permits the calculation of drop velocity along the interface of an inclined trickling film. Starting from a balance of forces around a single particle, the model provides the equation of motion for a steady motion of single particles in a stratified two-phase flow. Several assumptions and considerations were necessary to solve this equation, such as taking into account the influence of the wall and of flow resistance. The model calculation assumes Newtonian liquids and laminar, smooth trickling films. A comparison with experimental results confirms that the drop motion behaviour is well reproduced.
    Additional Material: 14 Ill.
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  • 35
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    Chemical Engineering & Technology - CET 10 (1987), S. 291-296 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of extraction processes with chemical reaction was studied experimentally on the system copper/Acorga PT 5050 and quantified according to meaningful kinetic models. These were coupled with other models describing the behaviour of dispersions in columns in order to permit a computer aided simultation of reactive extraction. Thus, a better prediction of column performance is achieved.
    Additional Material: 8 Ill.
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  • 36
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    Chemical Engineering & Technology - CET 10 (1987), S. 312-322 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Existing heat exchanger design criteria do not satisfy the continually increasing requirements for greater efficiency or mass flux and energy throughput. Occasionally, failures appear even after only a few hours of operation, as shown in section 3. A long series of experiments, often carried out on original scale, did lead to the derivation of a large number of empirical expressions; however, physical explanations of the complex tube-failure interactions could not as yet be found. In contrast, experiments with a well defined simple model, whereby the tube deflections were recorded digitally and, at the same time, tube-fluid interactions were registered on a high-speed film, show that elementary “fluid transport mechanisms” control the stability behaviour of the heat exchanger tubes. Vibration excitation mechanisms such as “galloping”, “jet switching” and “whirling” (fluid elastic coupling) proved, with their characteristics, as typical for the vibration behaviour of single rows within the tube array, but not for the vibration phenomena of tube bundles.
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  • 37
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    Chemical Engineering & Technology - CET 10 (1987), S. 297-305 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Against the background of long-term availability of natural gas, its present technology and future prospects are described. Particular emphasis is put on the oxidative coupling of methane to C2+ hydrocarbons: (1) Catalyst development, activity, selectivity and deactivation as well as reactor operation are discussed; (2) a tentative process scheme is put forward and its economics evaluated with respect to ethylene production.
    Additional Material: 8 Ill.
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  • 38
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    Chemical Engineering & Technology - CET 10 (1987), S. 323-329 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The conversion of a number of alcohols, ethers, ketones, aldehydes, carboxylic acids, esters, and cyclic compounds and their mixtures on H-ZSM-5 at 673 K was investigated. These compounds can be easily converted to aromatic hydrocarbons if the C/H ratio of the molecule fragment, remaining after elimination of oxygen as water, is less than 0.62. At higher C/H ratios, coking of the catalyst increases, thus reducing its lifetime, a difficulty which can be overcome by hydrogenation of these compounds prior to their conversion over H-ZSM-5. A procedure is proposed for converting at least a part of organic waste chemicals to valuable products instead of burning them.
    Additional Material: 8 Ill.
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  • 39
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental study of the flow of phosphate mine tailings was carried out in order to characterize these suspensions of fine particles for pipeline transport. Rheological measurements with a rotating cylinder viscometer indicate a viscoplastic behaviour which can be represented by a Herschell-Bulkley or by a Casson model. The variation of the parameters of these models with solids concentration reveals a change in the behaviour at a concentration of 10 to 15%. The pressure drops were measured during flow in capillary tubes, in both laminar and turbulent regimes. The variation of the pressure drop coefficient (Fanning friction factor) as a function of the generalized Reynolds number confirms the validity of the employed rheological models. The results are in good agreement with measurements made in pipes of industrial size. The velocity profiles measured with a novel ultrasonic velocimeter demonstrate the influence of the rheological behaviour on the yield and wall stresses.
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  • 40
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    Chemical Engineering & Technology - CET 10 (1987), S. 330-337 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The aim of this investigation is to show the demarcation of two possible mechanisms for surface deposition of fine particles on the rear surface of single spheres. By means of single particle trajectory computation, based on numerically determined flow fields (Remax = 103), it is shown that the mere existence of a wake is not in itself sufficient to produce eddy deposition. In addition, the particle's motion must undergo a lateral transfer promoted by fluid trubulence, in order to effect eddy deposition commencing at a Reynolds number of about 100. On the other hand, rear deposition, influenced by electrostatic forces, especially by the Coulomb force, is possible at any Reynolds number. Consequently, for Reynolds numbers of less than 100, only electrostatic effects can produce rear surface deposition. In the range of high Reynolds numbers, the coexistence of both mechanisms is possible. Very high Reynolds numbers (Re 〉 103) and low Stokes numbers indicated the predominance of the electrostatic effect over eddy deposition, whereas at very high Reynolds numbers and medium to high Stokes numbers the electrostatic effect is only predominant in presence of high electrostatic charges.
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  • 41
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    Chemical Engineering & Technology - CET 10 (1987), S. 349-352 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simplified reactor model can be used for predicting the performance of an industrial VGO-treater. Laboratory-scale experiments performed on the same feed and catalyst as those in the industrial unit lead to a reactor simulation which agrees well with the data from this unit. In the laboratory experiments, it is possible to overcome the specific hydrodynamic problems of tricklebed reactors by appllying the catalyst dilution technique. Results obtained by this technique allowed the development of a reactor model which enables the user to simulate the adiabatic behaviour of the industrial reactor. In this way, the significant gap between the reaction temperature in the isothermal laboratory reactor and the WABT of the industrial adiabatic reactor can be bridged.
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  • 42
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    Chemical Engineering & Technology - CET 10 (1987), S. 361-367 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The rate behaviour of multi-step reaction systems is difficult to model. Concentration-controlled investigations in a recycle reactor provide new tools for this purpose, e.g. the possibility to decompose a network into single reaction steps. Methanation of carbon monoxide over a supported Ni catalyst could be shown to be accompanied to a considerable extent by the shift reaction, and to a lesser extent by direct hydrogenation of carbon dioxide. Deactivation of the catalyst was measured at definite gas compositions. The two main steps show different responses to deactivation: Separable kinetics was found only for the methanation step. Power law rate equations were fitted to the rate data of the individual reaction steps to represent the main features of their kinetic behaviour. Some aspects of deactivation kinetics are also discussed.
    Additional Material: 8 Ill.
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  • 43
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    Chemical Engineering & Technology - CET 10 (1987), S. 368-375 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This contribution presents the measurements of bubble behaviour in presence of A, B and D powders in a semi-industrial scale pressurized fluidized bed. Local measurements were taken at static pressures of 0.2, 1.0 and 2.5 MPa, using capacitance probes. Quartz sand with mean particle diameter of 157 μm was fluidized in small “two-dimensional” transparent equipment with Frigen R 115. In addition, pressure fluctuations in the bulk of the fluidized bed with inner diameter of 0.4 m were studied experimentally.
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  • 44
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    Chemical Engineering & Technology - CET 10 (1987), S. 353-360 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Correlation flowmeters have been used in the scientific field for many years and are actually gaining greater commercial importance due to an increasing number of applications in industrial plants. The importance of the correlation method is based on the fact that essentially no alternatives exist for measuring velocity and mass flow rate in pneumatic conveyors. However, the hitherto employed transit time correlation method leads to results which are clouded by uncertainties. The commonly used theoretical model of the measurement process does not explain these effects satisfactorily. Therefore, the theory of non-intrusive flow sensors is reinvestigated from a physical standpoint. The derived model permits a discussion of the transit time correlation method in some detail. Furthermore, this model leads to an alternative sensor arrangement and signal processing scheme which makes it possible to measure the true mean velocities. Examples of experimental results are given.
    Additional Material: 13 Ill.
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  • 45
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the simulation of steady- and non-steady-state behaiour of separation columns, a simulation program was developed and employed for the calculation and optimization of methanol-water separation. The demand for increasingly higher purities and energy-saving optimization of plants results in complex column configurations and thus in complex control schemes. The number of possible control schemes was reduced on the basis of heuristic rules. By simulating the process, the optimum control and manipulative variables and measuring points were determined from the reduced number of control concepts. A control scheme was introduced. The model was verified by simulation of the dynamic behaviour of the process. The investigation included the effects of computing technique, time interval, model reduction and tray hold-up on the results. Thus, various effects and interactions were verified theoretically with respect to the robustness of the model. This was followed by a simulation of the non-ontrolled and controlled column. By implementing the controllers in the existing column program, the computer can predict the control parameters. These parameters were checked and corrected when the metahnol-ater column was put in operation. In the start-up phase, major problems were caused by the sensitivity and failure rate of density, throughput and pump measuring sensors. Feed impurities were another source of problems. Operation with high product purities is possible, with a side stream to discharge impurities.
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  • 46
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    Chemical Engineering & Technology - CET 10 (1987), S. 382-389 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Phase equilibria in the n-hexadecane-water-hydrogen and n-hexadecane-benzene-water-hydrogen systems were determined experimentally at temperatures between 200 and 350°C and pressures between 100 and 300 bar. At high water concentrations, three-phase equilibria were observed. Two-phase regions could be correlated with a modified Redlich-Kwong equation of state. The influence of interaction parameters on the calculated miscibility gaps was investigated. On application of mean interaction parameters, it is possible to calculate phase equilibria at different pressures or temperatures with the same set of parameters. In the ternary system, the three-phase regions could be calculated from the correlated binodal curves of two-phase regions. In the quaternary system, cross-sections through the vapour-liquid miscibility gap could be successfully correlated.
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  • 47
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    Chemical Engineering & Technology - CET 10 (1987), S. 375-382 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the extraction literature, no attention has been given so far to differential calculation models for countercurrent extraction columns which take into account the changes in flow rates of the phases as a result of transferred mass, and which also reflect the variations in interfacial area per unit volume and in axial dispersion coefficients since these depend on the flow rates. The present contribution puts forward a formulation of such a model; this results in a set of non-linear differential equations with separated boundary conditions, representing the feeds at either side of the extraction column. This set of differential equations must be solved numerically. The model is illustrated by a sample calculation on the extraction of benzene with furfural. In this (realistic) example, the interfacial area per unit volume varies from bottom to top by a factor of 3. Ignoring this effect would obviously result in serious under- or overdesign.
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  • 48
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    Chemical Engineering & Technology - CET 10 (1987), S. 405-410 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Starting from the assumption that the growth of desublimed layers is governed mainly by heat and mass transfer, the authors present a model based on conditions in the diffusion boundary layer and suggest that the “hoarfrost”Hereafter the term frost will be used instead of hoarfrost. density depends on only one parameter. The discussion accounts for the process determining factors, i.e. the growth rate, mass transfer and gas concentration. The theoretical relationship is confirmed by the authors' own experiments on two systems and data from literature. The relationship can be established by a few laboratory experiments and permits the calculation of frost density and of associated variables, thus facilitating the optimization of desublimator design.
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  • 49
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    Chemical Engineering & Technology - CET 10 (1987), S. 411-419 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This contribution reviews the work performed mainly at Bergbau-Forschung during the past few years. First, it deals with the quantitative description of gasification kinetics, taking into account the pressure of the gasifying agent and partial pressures of product gases. Thereby, a method and quantitative data are provided for the calculation of reaction rates for uncatalyzed and potassium-catalyzed gasification, on the example of chars from high volatile bituminous coals. In addition, a method for characterization of internal surface area by oxygen chemisorption with respect to char reactivity has been improved. Progress has also been achieved in the assessment of the impact of pyrolysis conditions, especially the time-temperature profile during char formation, on its chemical activity during subsequent use.
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  • 50
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    Chemical Engineering & Technology - CET 10 (1987), S. 398-404 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Previous investigations have shown that the specific energy input is the overall parameter of influence on product size during communition in agitated ball mills, from laboratory up to industrial scale. The specific energy input is the introduced energy related to the amount of comminuted material. This parameter can be used for mill scale-up. Consequently, a method had to be found of introducing power into the mill so as to obtain a given specific energy input. For this purpose, stirring tests with purely Newtonian liquids were carried out in absence of solids and hence, without comminution. Mathematical models are presented which describe the power consumption in agitated ball mills in absence of grinding beads. In addition, tests with grinding beads filling were also performed, leading to scale-up guidelines with respect to power consumption. Finally, the influence of size and material of grinding beads was investigated.
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  • 51
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A pressure swing adsorption process for hydrogen recovery from coke oven gases comprises the steps of adsorption at pressures above 6 bar, cocurrent and countercurrent depressurization, purging with hydrogen at ambient pressure and repressurization. The process was investigated in the cyclic mode, on a laboratory scale, using an adsorber filled with 1.3 litres of carbon molecular sieve. Based on the test results of concentrations and pressures within the adsorber during complete cycles, a pseudo-homogeneous model was developed for the adsorption step. Adsorption equilibrium parameters were determined by separate measurements, while the transport parameters were evaluated by fitting the experiments of the fixed bed adsorber. It was possible to consider the residual load, resulting from an incomplete regeneration, by the assumption of a load distribution in the inlet region of the adsorber.
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  • 52
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An important aspect of nuclear and chemical reactor safety is the ability to predict the maximum or critical mass flow rate from a break or leak in a pipe system. At the beginning of such a blowdown, if the stagnation condition of the fluid is subcooled or slightly saturated thermodynamic non-equilibrium exists in the downstream, e.g. the fluid becomes superheated to a degree determined by the liquid pressure. A simplified non-equilibrium model, explained in this report, is valid for rapidly decreasing pressure along the flow path. It presumes that fluid has to be superheated by an amount governed by physical principles before it starts to flash into steam. The flow is assumed to be homogeneous, i.e. the steam and liquid velocities are equal. An adiabatic flow calculation mode (Fanno lines) is employed to evaluate the critical flow rate for long pipes. The model is found to satisfactorily describe critical flow tests. Good agreement is obtained with the large scale Marviken tests as well as with small scale experiments.
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  • 53
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    Chemie Ingenieur Technik - CIT 45 (1973) 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 54
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 8-18 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Es wird eine Einführung sowie eine Übersicht über die Prinzipien und Meßmöglichkeiten der Teilchengrößenanalyse gegeben. Besonderer Wert ist dabei auf eine kurze zusammenfassende Darstellung der nicht nur für den Neuling verwirrenden Vielfalt von Meßmöglichkeiten gelegt, wobei jedoch neuere, noch nicht allgemein verfügbare Techniken weitgehend unberücksichtigt bleiben müssen. Die Einarbeitung in spezielle Gebiete der Teilchengrößenanalyse wird durch ein reichhaltiges Literaturverzeichnis erleichtert.
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  • 55
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973), S. 25-29 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Im Gegenstrom von Gas und Flüssigkeit durchströmte Füllkörperapparate mit bewegten, aufgewirbelten Füllkörpern werden seit etwa einem Jahrzehnt zur Durchführung von Stoffaustauschprozessen und zur Naßentstaubung eingesetzt. Über systematische Untersuchungen der damit verbundenen verfahrenstechnischen Probleme wurde bisher in der westlichen Literatur kaum berichtet. Aufgrund einer Auswertung der zur Zeit zugänglichen Literatur werden die strömungstechnischen Eigenschaften und die Stoffaustauscheigenschaften beschrieben. Der Apparat erlaubt wesentlich höhere Gas- und Flüssigkeitsdurchsätze als bisher bekannte Gegenströmer, auch bezüglich der Stoffaustauschwirksamkeit ist er anderen Apparatebauarten (z. B. Bodenkolonnen, Füllkörpersäulen) überlegen.
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  • 56
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 18-24 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Für die Staubgehaltsbestimmung in strömenden Gasen werden eine große Zahl von Verfahren eingesetzt. Die Messung des absoluten Feststoffgehaltes in strömenden Gasen erfolgt hierbei fast ausschließlich durch Absaugen und Analysieren eines Teilgasstromes. Neben der einwandfreien Ausführung der Meßsonde und der Wahl geeigneter Meßorte ist vor allem die geschwindigkeitsgleiche Absaugung des Teilgasstromes von Einfluß auf das Meßergebnis. Bei nichtgeschwindigkeitsgleicher Absaugung ergeben sich Meßfehler, die mit wachsender Abweichung der Absauggeschwindigkeit von der Kanalgeschwindigkeit und mit der Größe der Feststoffteilchen zunhmen. Die Größe des Meßfehlers kann sowohl theoretisch als auch experimentell bestimmt werden. Nach einem Vergleich der unterschiedlichen Verfahren zur Bestimmung des Meßfehlers wird ein einfach zu handhabendes Diagramm aufgestellt, das eine nachträgliche Korrektur der Meßergebnisse gestattet.
    Additional Material: 15 Ill.
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  • 57
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 1-7 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mit zunehmender Anwendung der Flüssigkeitszerstäubung gewinnt die Tropfengrößenbestimmung an Bedeutung. Ihre Meßverfahren sind schwieriger und jünger als die der Korngrößenbestimmung und ihr an Genauigkeit unterlegen. Abgesehen von einigen speziellen Methoden ist man bei Regen und Sprüh (3000 bis 30 μm) meistens immer noch darauf angewiesen, die Tropfen auf einer geeigneten Unterlage aufzufangen und mikroskopisch auszumessen. Nebel (〈 30 μm) kann man dagegen Meßgeräten zuführen und dort fraktioniert nach Tropfengröße abscheiden (Kaskadenimpaktor, Frittenkaskade, Meßzyklone). Aus den Niederschlagsmengen lät sich mit Hilfe der durch einmalige Eichmessungen bekannten Tropfengrößen das zu messende Tropfenspektrum näherungsweise ermitteln. Neuere, optische Verfahren messen die Tropfen ohne vorherige Abscheidung. Bereits im Handel befindliche Zählgeräte registrieren das Streulicht der einzelnen Tropfen. Bei der Tropfenholographie fertigt man eine Momentaufnahme der Tropfenwolke an. Die anschließende räumliche Bildwiedergabe erlaubt das Ausmessen und Auszählen der Tropfen.
    Additional Material: 12 Ill.
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  • 58
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 42-46 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 59
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die Bedeutung kinetischer Untersuchungen an Reaktionssystemen, bei denen die Luftverunreinigungen in geringer Konzentration vorliegen, für die Abgasreinigung bzw. Geruchsbeseitigung sowie die Vorgänge in der verunreinigten Atmosphäre werden aufgezeigt. Ferner werden zwei spezielle Beispiele gebracht, und zwar erstens die Reaktionen von Mercaptanen mit Ozon. Für die Messungen wurde ein Durchflußreaktor verwendet. Für die Anfangsgeschwindigkeiten ergab sich ein Zeitgesetz 2. Ordnung. Die Geschwindigkeitskonstante nimmt mit steigender Kettenlänge zu. Als Reaktionsprodukte wurden im wesentlichen Aldehyde und Disulfide identifiziert. Als zweite Reaktion wurde die Oxidation von Kohlenwasserstoffen am Beispiel des Gemisches Äthylen/Luft in einem wabenförmigen Katalysator (Al2O3 mit Pt imprägniert) untersucht. Im Diffusionsgebiet stehen die Versuchsergebnisse in erster Näherung bei hinreichend kleiner Konzentration mit der Theorie von Seifert und Schmidt in Einklang.
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  • 60
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 36-41 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Manuelle Methoden der Abgasmessung ergeben oft unzureichende Informationen über die zeitliche Variation der Menge und Zusammensetzung von Emissionen, wodurch ein Bedarf an Meßmethoden für kontinuierliche Registrierungen besteht. Bei der Messung von Schornsteinabgasen müssen bestimmte Forderungen an den Ort der Probeentnahme gestellt werden, um eine zufriedenstellende Repräsentativität hinsichtlich Art und Menge der Luftverunreinigungen zu erhalten. Bei der Wahl der Analysenmethode müssen die lokalen Voraussetzungen, die Konzentrationen, Art und Zusammensetzung der Verunreinigungen sowie die Strömungsverhältnisse im Schornstein berücksichtigt werden. Bei der Wahl des Instumententyps sind u. a. die Art der Verunreinigung, störende Komponenten in den Abgasen, die gewünschte Genauigkeit der Meßresultate, der Meßbereich des Instrumentes, die Betriebssicherheit und Wirtschaftlichkeit zu beachten. Es wurden verschiedene kontinuierlich registrierende Analysengeräte unter praktischen Bedingungen getestet und die Meßresultate mit denen verglichen, die durch manuelle Messungen erhalten wurden.
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  • 61
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 47-48 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 63
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  • 64
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 49-52 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
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  • 66
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    Chemie Ingenieur Technik - CIT 45 (1973) 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 67
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    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 68
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 53-57 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Möglichkeiten zur vergleichenden Beurteilung unterschiedlicher Ringfüllkörpertypen werden diskutiert. Dabei wird gezeigt, daß zur strömungstechnischen Beurteilung Untersuchungen des Druckverlustes einphasig durchströmter Schüttungen ausreichend sind. Neue Ergebnisse aus Untersuchungen des Druckverlustes luftdurchströmter Schüttungen aus dünn- und dickwandigen Pall-Ringen und halbhohen Ringen (h = 1/2 da) in Füllkörperrohren und -säulen werden angegeben und mit an Raschigring-Schüttungen ermittelten verglichen. Der Vergleich ermöglicht allgemeine Aussagen bezüglich des unterschiedlichen strömungstechnischen Verhaltens dieser drei Ringfüllkörpertypen.
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  • 69
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Es wird über Untersuchungen an Glocken- und Siebböden mit Durchmessern von 1,0 bis 4,8 m, die als ein-, zwei- oder vielflutige Konstruktionen arbeiten, berichtet. Dabei wird insbesondere der Einfluß des Flüssigkeitsgradienten vom Zu- zum Ablauf auf den Belastungsbereich, die Wirkung der Dampf- und Flüssigkeitsgeschwindigkeit auf das Mitreißen sowie Durchregnen die Änderung des Druckverlustes mit der Wehrhöhe untersucht. Für Regenschirmglockenböden werden Näherungsgleichungen zur Ermittlung der unteren Belastungsgrenze sowie des Druckverlustes mitgeteilt. Böden mit Regenschirmglocken zeichnen sich gegenüber anderen Konstruktionen durch erheblich niedrigere Mitreißanteile aus. Bei großen Kolonnendurchmessern wird durch eine Zentralsäule, die gleichzeitig die Sammlung, Mischung und Verteilung der Rücklaufflüssigkeit übernimmt, die Einhaltung der zur Erzielung eines guten Bodenwirkungsgrades erforderlichen Ebenheitstoleranzen wesentlich erleichtert.
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  • 70
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Es wird ein Verfahren beschrieben, mit dem die absatzweise Rektifikation binärer Gemische auf einem hybriden Analogrechner simuliert werden kann. Dabei wird vorausgesetzt, daß der Betriebsinhalt der Säule vernachlässigbar gegenüber dem Blaseninhalt ist. Es kann die Zerlegung idealer als auch nichtidealer Flüssigkeitsgemische bei Betrieb mit konstantem oder veränderlichem Rückfluß simuliert werden. Im Programm sind alle wichtigen Parameter wie Gleichgewichtskurve, Dampfstrom, Rücklaufverhältnis, Bodenzahl und Bodenaustauschgrad in einfacher Weise variierbar. Ergebnis der Rechnung sind die unmittelbar interessierenden zeitabhängigen Konzentrationsverläufe von Kopf- und Sumpfprodukt, wobei die erforderlichen Rechenzeiten sehr kurz sind. Mit dem Verfahren werden einige Beispielrechnungen durchgeführt.
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  • 71
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 67-74 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mit Hilfe einer Modellvorstellung für den flüssigkeitsseitigen Stoffübergang wird durch Auswertung zahlreicher Rektifizierversuche, die an Kolonnen mit 0,5 und 1 m Durchmesser bei Kopfdrücken von 5, bis 300 Torr durchgeführt wurden, eine Beziehung für die mittlere gasseitige Sherwood-Zahl der Sulzer-Gewebepackung herge leitet. Diese gilt für gasseitige Reynolds-Zahlen von 350 bis 2000. Eine Abhängigkeit der mittleren gasseitigen Sherwood-Zahl vom Kolonnendurchmesser und von der Packungshöhe wurde nicht festgestellt. Der Grund dafür liegt im intensiven seitlichen Transport der Gasphase gegenüber der Flüssigkeitsströmung. Der Anteil des gasseitigen Stoffübergangswiderstands am Stoffdurchgangswiderstand betrug bei den ausgewerteten Versuchen 74 bis 97%.
    Additional Material: 10 Ill.
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  • 72
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 74-80 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Es wird eine neue Siedegleichgewichtsapparatur beschrieben. bei der nicht wie bisher fast ausschließlich üblich die Zusammensetzung der miteinander im Gleichgewicht stehenden Flüssigkeits- und Dampfphase analytisch bestimmt wird, sondern im Durchlaufbetrieb unter stationären Bedingungen Siede- und Taupunkt eines vorgegebenen Gemisches gemessen werden. Der Vorteil der Methode liegt in der großen Zeit- und Arbeitsersparnis bei guter Genauigkeit, die mit der üblicher Siedegleich- gewichtsmessungen vergleichbar ist. Die Apparatur wurde bei 760 Torr an den Systemen Methanol/Wasser, Methanol/Benzol, Aceton/Benzol, Wasser/Äthylenglykol und Benzol/Anilin erprobt, für das System Benzol/Anilin außerdem bei 500 Torr. - Es erscheint möglich, die Apparatur für eine vollautomatische Messung von Siedegleichgewichtskurven weiter zu entwickeln. Die Voraussetzungen dafür werden rechnerisch geprüft.
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  • 73
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 83-88 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Eine exakte Analyse des Zweiphasenmodells ist wegen der großen Zahl der eingehenden Parameter ziemlich kompliziert. Es wird daher zuerst eine Analyse des katalytischen Rührkessels vorgenommen und dabei der Einfluß der einzelnen Parameter, wie z. B. Damköhler-Zahl, adiabatische Temperaturerhöhung, dimensionslose Wärmekapazität usw., auf den Bereich der mehrfachen Lösungen sowie der Instabilitäten ermittelt. Die auf diesem Wege gewonnenen Resultate werden auf eine Kaskade erweitert. In einem experimentellen Reaktor werden zum einen mehrfache Lösungen mit Hysterese „Zünden-Löschen“, zum anderen die Grenzzyklen für die Reaktion CO + 1/2 O2 → CO2 beobachtet. Die Ergebnisse der theoretischen Erwägungen werden von diesen experimentellen Beobachtungen bestätigt.
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  • 74
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 80-83 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The compound LaNi5 absorbs nearly 6 atoms of hydrogen per formula unit at an equilibrium pressure of 2.5 at and room temperature. LaNi5 exhibits a high rate of absorption and desorption of hydrogen and the heat of reaction is about 7.4 kcal/mol H2. The dependence of the equilibrium pressure in the two-phase region on temperature is utilized to compress hydrogen from 4 to 45 at, which are suitable working pressures for a hydrogen refrigerator. Three vessels containing LaNi5 are heated and cooled between 410 K and 290 K in cyclic operation. A system of selfoperating valves establishes a steady flow of hydrogen gas through a Joule-Thomson system. In the present design, employing precooling with liquid nitrogen at 78 K, 1 W of cold is produced at 26 K. Hydrogen-sorption properties of LaNi5 are given and the problems encountered in practical use of the material discussed.
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 95-97 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Chemieanlagen können hinsichtlich der Investitions- und Betriebskosten optimiert werden. Die Optimierung zerfällt in zwei Aufgaben: (1.) optimale Einzelteil-Dimensionierung und (2.) Verfahrensoptimierung. Streng genommen muß vor der zweiten Aufgabe immer die erste durchgeführt sein, da sonst ungleiche Verfahrensschritte miteinander verglichen werden. Für die zweite Aufgabe genügt die Angabe der erforderlichen Rendite (bzw. pay out time) für das zusätzlich investierte Kapital. Bei der ersten Aufgabe hat der gleiche Zahlenwert die Bedeutung der Grenzrendite für die jeweils letzte investierte Mark. Ein expliziter Zusammenhang zwischen der Gesamtrendite und dieser Grenzrendite läßt sich nur über Aufstellung der Investitionskosten als Funktion der Betriebskosten für den konkreten Fall gewinnen.
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 97-100 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 89-94 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die Umsetzung von gelöstem Kohlenmonoxid mit Wasser zu Wasserstoff und Kohlendioxid erfolgt in wäßriger Phase als homogene Reaktion gemäß - dcCO/dt = k1cCO. Bei der Reduktion von Kobalt-Ionen aus acetat-haltigen Lösungen mit Kohlenmonoxid reagiert zunächst gelöstes CO mit H2O zu H2 und CO2, anschließend wird das Kobalt mit diesem intermediär gebildeten H2 reduziert. Für die heterogen an Kobalt-Pulver (Fläche F) im Lösungsvolumen Vli ablaufende Kobalt-Reduktion mit H2 gilt - dcCo2+/dt = (k2F/Vli)pH2. Die Kobalt-Reduktion mit CO (Anfangsdruck pCO0) läßt sich durch die Gleichung - (dcCo2+/dt) Vli = k3pCO0 beschreiben. Bei ausreichendem Angebot an Fremdkeimen gilt in guter Nährung - dcCo2+/dt ∼ k1pCO0, d. h. die Wassergas-Reaktion bestimmt die Geschwindigkeit der Kobalt-Fällung.
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 101-105 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Für die Chargenkristallisation durch Kühlung wird mit Hilfe zweier simultaner Differentialgleichungen der zeitliche und temperaturmäßige Verlauf von Übersättigung, Keimbildungsanteilen, spezifischer Kristallfläche und Größe des mittleren Produktkorns berechnet. Zur Kritik der an zwei Beispielen erläuterten Methode wird der Vergleich von Keimzahl und Produktkornzahl herangezogen.
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 109-116 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nach einer allgemeinen Betrachtung über die Verarbeitung der Feinkornbaustähle wird zunächst auf die Warm- und Kaltverformung solcher Werkstoffe eingegangen und dann über ein neues Prüfverfahren zur Ermittlung der Schweißeignung von Baustählen und erhaltene Ergebnisse berichtet. Schließlich wird die Anwendung verschiedener Verarbeitungsrichtlinien in der Praxis behandelt.
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    Chemie Ingenieur Technik - CIT 45 (1973), S. 116-122 
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Zur Beurteilung der Eignung emaillierter Rührsysteme zum Homogenisieren von Flüssigkeitsgemischen mit geringen Dichte- und Zähigkeitsunterschieden wurden in einem weiten Viskositätsbereich Rührleistung und Mischzeit gemessen. Besondere Beachtung fand dabei die Erfassung der Meßpunkte im laminaren Gebiet, um die absolute Einsatzgrenze der untersuchten Rührsysteme feststellen zu können. Da in diesem Arbeitsbereich Einbauten keinen Vorteil mehr bieten, wurde zum Vergleich nur der ungestörte Behälterzustand in die Betrachtung mit einbezogen. Die Ergebnisse gestatten einerseits, den günstigsten Rührertyp und dessen optimale Arbeitsbedingungen zu ermitteln, andererseits eine Auswahl darüber zu treffen, welches Rührorgan bei vorgegebener Antriebsleistung noch die höchsten Viskositätsgrade beherrschen kann. Ein Hinweis zur generellen Klärung des Problems der absoluten Einsatzgrenze von Rührern wird gegeben.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 82
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nach der Beschreibung der bisher üblichen Verfahrensweise zur Gewinnung von wasserfreiem Natriumsulfat über vorherige Kristallisation von Glauber-Salz wird ein neues Verfahren vorgestellt. Bei diesem Prozeß wird zunächst wie bisher üblich Glauber-Salz durch Vakuum-Kühlungskristallisation gewonnen und dann geschmolzen. Die Mutterlauge gelangt anschließend aus dem Schmelzer in eine mehrstufige Eindampfanlage, die dampfseitig hintereinander geschaltet ist. Die Brüden aus der letzten Eindampfstufe beheizen den Heizkörper des Schmelzers. Pro Tonne Natriumsulfat werden nur noch 0,85 t Dampf benötigt. Neben der Energieeinsparung bringt dieses Verfahren durch entsprechende Schaltung und Ausführung wesentliche betriebliche Vereinfachungen. Die Verkrustungen werden auf ein Minimum herabgesetzt. Durch Anwendung dieses Verfahrens konnte eine bestehende Natriumsulfat-Anlage  -  ohne Neuinvestitionen auf der Glaubersalz-Seite und ohne Erhöhung des Dampfverbrauches - in ihrer Leistung um 66% erweitert werden.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 83
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In einem nichtthermischen Plasma werden aktive Spezies erzeugt, die zu chemischen Reaktionen führen. Im Hinblick hierauf läßt sich eine Optimierung entwickeln, die noch keine speziellen Eigenschaften des Plasmas enthält. Als erster Optimierungsschritt wird gefordert, daß der Anteil der elektrischen Leistung für die Aufheizung des Gases vernachlässigbar ist gegenüber dem Anteil für die Erzeugung der aktiven Spezies. Dies ist oberhalb eines kritischen Wertes des Energieverlustfaktors für die Elektronen gegeben. Als nächster Optimierungsschritt wird eine möglichst hohe Produktionsrate der angeregten Atome verlangt. Für Felder oberhalb des kritischen Wertes ist dies gleichbedeutend mit der Forderung nach einer hohen elektrischen Leistungsdichte. In den meisten nichtthermischen Plasmen läßt sich der erste Optimierungsschritt realisieren. Weitere Optimierungsschritte müssen für die einzelnen Entladungstypen getrennt diskutiert werden. Besondere Bedeutung kommt dabei der Gasströmung durch das Plasma zu.
    Additional Material: 9 Tab.
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  • 84
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973), S. 136-143 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 85
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973), S. 131-136 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bei der Extraktion von Butadien aus Crackschnitten werden in bestimmten Anlagenteilen die C4-Acetylene angereichert. Beim BASF-Verfahren wird diese Anreicherung unter etwa 1,4 bar absolut durchgeführt. Andere Verfahren benötigen hierbei höhere Drücke. An Gemischen, wie sie in der Anlage anfallen, werden Zerfallsmessungen mit verschiedenen Zündquellen durchgeführt, und es wird gezeigt, wie die maximal zulässige Vinylacetylen-Konzentration vom Partialdruck abhängt.
    Additional Material: 5 Ill.
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  • 86
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973), S. 143-143 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 87
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973), S. 143-144 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 88
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 89
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973), S. 144-144 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 90
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973), S. 145-148 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 91
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 92
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973) 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 93
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973), S. 149-153 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die Kupfer-Elektrolyse ermöglicht es im Rahmen der Kupfer-Verhüttung, reines Kupfer herzustellen, wie es für die Weiterverarbeitung benötigt wird. Einige wesentliche Gesichtspunkte für den Betrieb und die Planung der Kupfer-Raffinationselektrolyse werden erläutert und ausgehend hiervon Entwicklungstendenzen aufgezeigt. Durch apparative Verbesserungen, zweckmäßigere und verfeinerte Betriebskontrolle und Überwachung, neue Kolloid-Zusätze, allgemeine Mechanisierung und Automatisierung sowie dadurch erreichbare höhere Stromdichten ist es möglich, die Betriebskosten zu senken und den steigenden Qualitätsforderungen Rechnung zu tragen. Neue Arbeitstechniken, wie z. B. die Umkehrstrom-Elektrolyse, lassen darüber hinaus weitere Kostenvorteile erwarten.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 94
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die Solventextraktion von Metallen dient vorzugsweise der Aufkonzentrierung stark verdünnter und der Reinigung stark verunreinigter Lösungen. Hierbei interessieren besonders die Selektivität der verwendeten Substanzen und die Kosten des Verfahrens. In diesem Beitrag werden drei Anwendungsmöglichkeiten der Kombination Solventextraktion/Elektrolyse beschrieben: (1.) die Aufarbeitung armer oxidischer Erze durch H2SO4-Laugung sowie anschließende Solventextraktion und Elektrolyse, (2.) die Aufarbeitung von Kupfer-Endelektrolyten, (3.) die Aufarbeitung von Kupfer-Schrott durch ammoniakalische Laugung sowie anschließende Solventextraktion und Elektrolyse. Die Selektivität heute handelsüblicher Substanzen ist hervorragend. Von den Kosten des Verfahrens her gesehen können jedoch nur Rohstoffe verwendet werden, die nicht mit ihrem vollen Metallwert (abzüglich üblicher Umarbeitungslöhne) bezahlt werden müssen.
    Additional Material: 3 Ill.
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  • 95
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973), S. 161-164 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Kobalt und Nickel lassen sich nur dann in reiner Form kathodisch abscheiden, wenn der zirkulierende Sulfat/Chlorid-Elektrolyt ständig von Verunreinigungen durch chemische Methoden befreit wird. Elektrolysen ohne Diaphragma sind zwar billig und einfach zu betreiben, wegen der aufwendigen Reinigung aber auf Sondergebiete beschränkt. Diaphragmen erlauben es, die zu reinigende Elektrolyt-Menge auf 1/10 der bei Verfahren ohne Diaphragma benötigten Menge zu verringern. Die löslichen Anoden, die aus dem zu raffinierenden Metall bestehen, dürfen relativ große Gehalte an Verunreinigungen aufweisen; es ist sogar neuerdings möglich, Nickelstein unter Bildung von Elementarschwefel direkt zu elektrolysieren. Die Diaphragmen-Elektrolyse wird aufgrund vieler Vorzüge auch in Zukunft Verbreitung finden, obwohl das Hochdruck-Carbonylverfahren für Nickel ein reineres Metall verspricht. Die Verwendung von reinen Chlorid-Elektrolyten, die sicherlich günstigere Abscheidungsbedingungen schüfe, scheitert gegenwärtig noch an Werkstoff-Schwierigkeiten.
    Additional Material: 2 Tab.
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  • 96
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973), S. 157-161 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bei den verschiedenen Verfahren zur Zink-Erzeugung gewinnt die Zink-Elektrolyse einen immer größeren Anteil. Ihre Vorteile sind hohe Reinheit des Produkts, hohes Zink-Ausbringen und günstige Betriebsbedingungen. Dieser Beitrag gibt einen kurzen Überblick über den gegenwärtigen Entwicklungsstand der einzelnen Verfahrensstufen der Zink-Elektrolyse, wie Röstung, Laugung, Eisen-Fällung, Laugenreinigung und eigentliche Elektrolyse. Hierbei hat besonders die Fällung des Eisens in Form des Jarosit- oder Goethit-Typs anstelle der Eisenhydroxid-Fällung in den letzten Jahren zu entscheidenden Verbesserungen des Verfahrens geführt. Ferner hat der Übergang zur kontinuierlichen Laugung in Verbindung mit verbesserter Meß- und Regeltechnik einen störungsfreieren Betrieb ermöglicht.
    Additional Material: 3 Ill.
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  • 97
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die z. Z. außerordentlich niedrigen Aluminium-Preise machen es für die Erhaltung der Wettbewerbsfähigkeit der Aluminium-Hütten erforderlich, das Aluminium in der BRD mit möglichst geringen Herstellungskosten zu produzieren. Dieser Vorstellung entspricht eine Elektrolyseführung, in der der Stromausbeute vor der Ausnutzung der Produktionskapazität Priorität zuerkannt ist und diese nur insoweit ausgenutzt wird, als es für das Erreichen der der Finanzierung zugrundegelegten Jahresproduktion erforderlich ist. Am Beispiel einer Aluminium-Elektrolyse wird versucht, für eine Soll-Jahresproduktion von 22000 t Aluminium/Jahr darzulegen, wie durch Erhöhung der Stromausbeute der Verbrauch an elektrischer Energie, Anoden und Flußmittel gesenkt werden und damit die Wirtschaftlichkeit der Elektrolyse verbessert werden kann. Außerdem wird gezeigt, wie sich die Stromausbeute im Elektrolysebetrieb steigern läßt.
    Additional Material: 4 Ill.
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  • 98
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973), S. 1319-1319 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 99
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 100
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 45 (1973) 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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