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  • 1995-1999  (2,223)
  • 1935-1939
  • 1996  (2,223)
  • General Chemistry  (1,786)
  • Chemical Engineering  (437)
  • Nuclear reactions
  • 101
    Electronic Resource
    Electronic Resource
    Output-feedback control of nonlinear plants (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2540-2554 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For multiinput-multioutput nonlinear plants whose state-feedback control problem is solvable with complete or partial output linearization, the output-feedback problem is addressed by combining the state-feedback controller with a suitable closed-loop state inferer (detector). A candidate closed-loop detector was built to study the stability of the resulting plant-controller interconnection. As a result, sufficient conditions for closed-loop asymptotic nominal stability, as well as a systematic and simple design-tuning procedure, are obtained. The stabilization of an open-loop, unstable, free-radical homopolymerization reactor was studied as an application example.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420914
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  • 102
    Electronic Resource
    Electronic Resource
    Gas holdup in bubble column reactors operating in the churn-turbulent flow regime (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2627-2634 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A comprehensive experimental study of gas holdup in bubble columns of varying diameters, fitted with different distributor types, using several liquids is presented. Air was used as the gas phase. Experiments to test the influence of gas density were also carried out with He, Ar, and SF6. A generalization of the two-phase model for gas-solid fluidized beds was used to interpret the experimental data where the “dilute” phase is identified with the “large” bubble population and the “dense” phase with the liquid phase where the “small” bubble population is entrained. Gas holdups in dilute and dense phases were determined from dynamic gas disengagement experiments.In the churn-turbulent regime of operation, voidage of the gas in the dense phase was independent of the superficial gas velocity. Reilly et al.'s correlations for the gas holdup and superficial gas velocity at the regime transition point estimate the gas voidage of the dense phase and the superficial gas velocity well through this phase. Corresponding correlations of Wilkinson et al. significantly underpredict dense-phase parameters. The experiment showed that the dilute phase or large bubble holdup in bubble columns, operating at superficial gas velocities 〉 0.1 m/s, is independent of liquid properties, how the gas is distributed and the density of the gas phase. But it is affected significantly by the column diameter. Relying on hydrodynamic analogies with a gas-solid-fluid bed, a simple correlation was developed that is considerably more accurate than the Wilkinson correlation that significantly overpredicts large bubble holdup.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420923
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  • 103
    Electronic Resource
    Electronic Resource
    Model for the reaction-rate-limited dissolution of solids with Etch-rate heterogeneities (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2654-2660 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The coalescence of isotropic etch pits observed in the dissolution of semiconductor substrates is studied using a discrete model for the evolution of the surface under reaction-rate-limited conditions. The model discretizes the solid into cubic elements and repetitively applies dissolution rules to the individual elements. The rate of mass removal is based on the number and arrangement of the element's exposed faces and the specified reaction-rate parameters. Detailed knowledge of the surface normal is not required. The model shows that even at moderate etch pit densities, the effects of the coalescence do not significantly alter the trends observed for noncoalescing etch pits.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420926
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  • 104
    Electronic Resource
    Electronic Resource
    Autotuning for model-based PID controllers (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2687-2691 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420930
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  • 105
    Electronic Resource
    Electronic Resource
    Holdup and solvent extraction characteristics in electrostatic liquid-liquid contactor (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2683-2686 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420929
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  • 106
    Electronic Resource
    Electronic Resource
    Electrochemical process engineering: A guide to the design of electrolytic plant. By F. Goodridge and K. Scott, Plenum Press, 1995, 312 pp., $59.50 (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2698-2698 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420932
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  • 107
    Electronic Resource
    Electronic Resource
    PDF modeling of turbulent-mixing effects on initiator efficiency in a tubular LDPE reactor (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2926-2940 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of turbulent mixing in the reaction zone of a tubular low-density polyethylene reactor was studied by combining a Lagrangian composition probability density function (LCPDF) code with a computational fluid-dynamics code. Because the LCPDF code can treat the chemical reaction terms in a turbulent flow without resorting to moment closures, it is used to describe the temperature and scalar fields of reactants including initiator and monomer molar concentrations, and the moments of the molecular weight distribution. The chemical reaction terms are efficiently dealt with using a three-parameter chemical lookup table that contains the temperature and composition changes as functions of initiator and monomer concentrations and temperature over a small time step. The reaction-rate constants from the study of Lee and Marano (1979) are functions of temperature and pressure. The flow fields are obtained using the k - ε turbulence model. Because the temporal and spatial evolution of all fields in the reactor can be simulated, it is possible to study the effect of the initiator injection location, flow rate and temperature of the monomer and initiator feed streams on polymerization in considerable detail. Moreover, by observing the probability distribution of the composition fields, a better understanding of hot-spot formation is achieved, leading to improved reactor designs.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421020
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  • 108
    Electronic Resource
    Electronic Resource
    Particles flow pattern and local heat transfer around tube in moving bed (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1621-1626 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Flow visualization of flowing particles around a tube of various types of tube arrangements in a moving bed was studied using X-ray video films to obtain a relation between particles behavior and local heat-transfer coefficients. A stagnant part of solid particles was observed on the tube in the case of a staggered arrangement. This part did not appear in the case of the single tube and the single row of tubes. The measured local heat-transfer coefficients around a tube was decreased in this stagnant part. Furthermore, influences of different tube arrangements both on flow patterns of particles and on local heat-transfer coefficients between tubes and bed were examined.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420613
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  • 109
    Electronic Resource
    Electronic Resource
    Statistics of multiple particle breakage (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1600-1611 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method for generating theoretical breakage distribution functions for multiple particle breakage is presented. It starts with the joint probability function that accounts for all the child particles; it is then reduced to the marginal probability function commonly used in the breakage equation. This method is flexible enough to allow the user to choose the number of child particles and the functional form to be used. The method is demonstrated with both product and summation functions with a power-law form. To facilitate the use of these theoretical functions for statistical analyses, a companion discretized breakage equation is developed. The new equation guarantees the conservation of mass and correct prediction of the total number of particles despite discretization. It is easy to use because it is a set of ordinary differential equations and applicable to both equal-size and geometric-size intervals. Simulation results show that different breakage distribution functions coupled with different breakage rates can produce almost indistinguishable particle-size distributions, signifying the need for further work in this area.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420611
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  • 110
    Electronic Resource
    Electronic Resource
    Coagulation and fragmentation: Universal steady-state particle-size distribution (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1612-1620 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A population balance model presented describes simultaneous coagulation and fragmentation during shear-induced flocculation. Given sufficient time, a floc-size distribution reaches steady state that reflects the balance between coagulation and fragmentation. The model agrees with experimental data for the evolution of the average floc size. Higher shear shifts the steady-state size distribution to smaller sizes. When the steady-state size distributions obtained at various shear rates are scaled with the average floc size, however, they collapse onto a single line. This indicates that the steady-state floc-size distribution is self-preserving with respect to fluid shear. This distribution is universal for the employed coagulation and fragmentation rates provided that less than 5% (by number) of the particles remain unflocculated. This result is supported with experimental data on shear-induced flocculation of polystyrene particles, although a detailed quantitative comparison is limited by the irregular structure of the flocs.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420612
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  • 111
    Electronic Resource
    Electronic Resource
    Transport phenomena and kinetics in an extravascular bioartificial pancreas (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2668-2682 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A bioartificial pancreas, consisting of immobilized islets encapsulated within hollow fibers, is investigated as an alternative treatment for insulin-dependent diabetes. A mathematical model is developed to determine whether this configuration of the bioartificial pancreas can yield an insulin response to a glucose challenge with the appropriate dynamics in diabetic humans. The model consists of the 2-D mass-conservation equations for glucose and insulin within the hollow fiber and capillaries. The equations contain terms for insulin-production kinetics by porcine islets and glucose-consumption kinetics. The boundary conditions account for transport resistances of the fiber membrane, the tissue surrounding the implant, and a thin film within the capillaries. The equations are coupled to a pharmacokinetic model of the circulatory system. The calculations show that an optimized design with this configuration will be feasible for human use and requires a total volume of 4.6 mL to reach the target insulin concentration in the bloodstream following a glucose challenge. The parameters and processes controlling the system performance are discussed.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420928
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  • 112
    Electronic Resource
    Electronic Resource
    Innovations in supercritical fluids: Science and technology. Edited by K. W. Hutchenson and N. R. Foster, ACS Symp. Ser. 608, American Chemical Society, 1995, 408 pp., $125.95 (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2698-2699 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420933
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  • 113
    Electronic Resource
    Electronic Resource
    Lateral thermal dispersion in gas-liquid cocurrent downflow through packed beds (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2977-2983 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421025
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  • 114
    Electronic Resource
    Electronic Resource
    Reaction coordinates for heterogeneous flow reactors: Physical interpretation (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2987-2989 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    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
    URL: http://dx.doi.org/10.1002/aic.690421027
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  • 115
    Electronic Resource
    Electronic Resource
    Computational modeling in semiconductor manufacturing. Edited by M. Meyyappan, Artech House, Norwood, MA, 1995, 363 pp., $89.00 (hardcover) (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2994-2995 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421031
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  • 116
    Electronic Resource
    Electronic Resource
    Diffusion measurements through embedded zeolite crystals (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 3001-3007 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the first time, a macroscopic method was used to measure directly diffusivity of fast diffusing species such as methane in silicalite. A form of Wicke-Kallenbach technique was applied to measure intracrystalline diffusivity. The technique uses a single embedded zeolite crystal as a membrane and a mass-selective detector to determine the transient mass response and hence the diffusion flux passing through the membranne. A concentration-difference driving force is used rather than a pressure-difference driving force. The diffusivities calculated from both adsorption and desorption transients were in excellent agreement, thus providing a check for the self-consistency of the data. The diffusivities of carbon dioxide, methane, ethane, propane and butane in silicalite between 30 and 70°C have been compared with those from the literature. The diffusivities reported here are between those measured with microscopic methods and those measured with other macroscopic methods.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421102
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  • 117
    Electronic Resource
    Electronic Resource
    Measurement of transverse and axial apparent dispersion coefficients in packed beds (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 3041-3054 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The axial and transverse apparent dispersion coefficients of three solvents in two packed chromatographic columns were determined by pulsed-field-gradient nuclear-magnetic resonance in a range of mobile phase velocity. The column beds were packed with 5- μm particles of porous C18 silica or 30-μm particles of silica. The solvents used were methanol and acetonitrile (in an 80:20 ACN/water solution) in the former case and acetone in the latter. The coefficients were determined over a range of particle Peclet numbers from less than 0.1 to approximately 10 in the former case and 40 in the latter. The data obtained with short dispersion times were fitted to the correlations suggested by Giddings, Horvath and Lin, Huber, and Knox. These data agreed well only with the Giddings equation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421106
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  • 118
    Electronic Resource
    Electronic Resource
    Synthesis of waste interception and allocation networks (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 3087-3101 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article introduces the novel concept of synthesizing waste-interception networks (WINs) and incorporates it within a mass-integration framework for the global allocation of pollutants. The essence of this notion is to provide selective interception and rerouting of undersirable species at the heart of the process instead of dealing with the pollutants in the terminal waste streams. It also provides a unified framework for simultaneously tackling gaseous and liquid pollution. Several tools are developed to track the pollutant throughout the process and determine the optimal interception policies. The problem is formulated as an optimization program that seeks to determine the optimum locations for intercepting the pollutants, extent of separation, and separating agents to carry out the interception tasks. Furthermore, the WINs can be used within a mass-integration scheme for the global allocation of species throughout the plant. These new concepts and associated mathematical formulation are demonstrated using a case study on the removal of a chlorinated hydrocarbon. This approach has benefits over conventional recycle/reuse (such as MEN synthesis).
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421109
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  • 119
    Electronic Resource
    Electronic Resource
    Characteristics of a new gas-induced reactor (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 3146-3152 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A newly developed gas-induced reactor for gas-liquid heterogeneous reactions presented here has no baffle on the inner wall of the tank body. Inside the reactor tank, two in-series 45° pitched blade downward turbines enclosed by a draft tube were employed. As the turbines rotate at high speeds, a central gas vortex is formed downwardly along the central shaft from the free surface of the liquid toward the upper turbine. The gas is then induced by the upper turbine and mixes with the input gas. After that, the mixed gas is broken into bubbles by the lower turbine and dispersed through the liquid vortex. With the formation of gas and liquid vortexes, the reactive gas was able to circulate in the liquid phase to achieve high gas utilization. The experimental studies were on the heterogeneous ozonation reaction of a reactive dye (C.I. Reactive Blue 19). Major experimental parameters, such as impeller speed, input concentration of ozone, input flow rate of ozone and liquid volume, were changed to investigate the characteristics of the gas-induced reactor. This gas-induced reactor achieved high gas utilization ratio, short reaction time, and high recovery of the unreactive gas.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421114
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  • 120
    Electronic Resource
    Electronic Resource
    Study of polymer melt flow in sequential injection molding process (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1706-1714 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental studies of polymer melt flow in the filling and post-filling stages of the injection molding process were performed using the sequential injection of transparent and colored polystyrene resin. Effects of fountain flow in the filling stage, geometrical factors caused by edges and corners, as well as flow through contractions and expansions, were identified. Significant polymer melt flow which increases with increased packing pressure was observed in the post-filling process. The melt flow is more concentrated around the gate area than away from the gate. It was also found that the polymer melt flows across the gap center, resulting in partial annihilation of the weld line. Simulations based on the control-volume/finite-element method employed within each gapwise layer combined with the dual-filling-parameter technique were developed to trace the advancements in melt fronts for both skin and core materials. Numerical simulations show reasonable consistency with experimental results in both skin and core material distribution. If the edge effect is taken into account using a shape factor as a geometrical correction, the simulation accuracy is further improved.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420622
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  • 121
    Electronic Resource
    Electronic Resource
    Effect of powder bed on critical heating rates for thermolysis of ceramic injection moldings (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1715-1722 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mass transport during pyrolysis of the degradation product of a polymeric binder used for ceramic molding is analyzed. Two series resistances to transport are incorporated: the diffusion of the product of degradation through its parent polymer during decomposition and the permeation of vapor through a static powder bed used to support the molding. The model predicts the critical rate of heating, Zc, above which defects caused by boiling of the organic phase occur at the center of the molding. For the system modeled, the permeability of the powder bed has little effect on Zc if the moldings are small but this is not the case for large moldings where well-packed fine powders should be avoided and the thickness of the powder bed should be kept to a minimum.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420623
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  • 122
    Electronic Resource
    Electronic Resource
    Masthead (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996) 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421201
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  • 123
    Electronic Resource
    Electronic Resource
    Self-diffusion in liquids predicted by a theory of flow through granular media (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 3333-3339 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new semiempirical model for prediction of self-diffusion phenomena in liquids is proposed. Assuming anlogy between the concept of a free volume in liquids and a porosity of a granular medium, a capillary model of the granular bed and the Kozeny-Carman theory was applied to determine self-diffusion coefficients in liquids. The dimensionless free volume in liquids was evaluated using a combination of the proposed dependence and an appropriate formula available in the literature. The new model was tested for 89 sets of data concerning self-diffusion of different chemical substances at several values of a temperature. The average error of a prediction was between ± 1% and about 3% for some data points.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421205
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  • 124
    Electronic Resource
    Electronic Resource
    Corrections (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1771-1771 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420628
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  • 125
    Electronic Resource
    Electronic Resource
    Mathematical modeling of supercritical extraction of sage oil (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1765-1771 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Modeling of supercritical CO2 extraction of essential oils from leaves was studied using sage at 90 bar (9 MPa) and 50°C. The fractional separation of the extracts enabled essential oil to be obtained. Four mean sage particle sizes ranging from 0.25 to 3.10 mm were tested. The model proposed was based on differential mass balances performed along the extraction bed. Experimental data suggest that the internal mass transfer was the controlling stage for the extraction process. Different hypotheses were tested on vegetable matter geometry, and their incidence on the model performance was evaluated. The particle shape proved to be a key factor in fitting experimental results, which were fairly good when the conventional spherical geometry was replaced by a realistic slab geometry. Diffusivity of the solute in the solid matrix was used as the only adjustable parameter of the model; its best fit value was 6.0 × 10-13 m2/s. The effect of the introduction of particle-size distribution into calculations was also tested. To verify if the external mass-transfer mechanisms influence the extraction process, experiments at two different CO2 flow rates were also performed. Simplified models were also considered, and the extent of approximations was evaluated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420627
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    Dynamics of the free rise of a light solid sphere in liquid (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1789-1792 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420630
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    New approach to analysis and design of Smith-predictor controllers (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1793-1797 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420631
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  • 128
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    Measuring vapor-liquid equilibrium for aqueous-organic systems: Review and a new technique (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1772-1788 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The vapor-liquid equilibrium (VLE) of aqueous-organic mixtures is important in understanding the physical chemistry behind the contamination and remediation of contaminated surface water, ground water and unsaturated soils. The state of the science is assessed, and available VLE and solubility data are reviewed comprehensively for several organic compounds. Benzene, toluene, o-, m-, p-xylene, ethylbenzene, chloroform, 1,1,1-trichloroethane (TCA), and trichloroethylene (TCE) were included in this study. Correlations are provided for estimation of VLE as a function of temperature. A new VLE apparatus was developed to extend experimental techniques found in the literature. Partitioning data for several aqueous-organic systems were measured. The collected data compared very favorably to data available in the literature. The new procedure is capable of providing high-quality data over a wide range of liquid concentrations and temperatures.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690420629
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    Masthead (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996) 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420701
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  • 130
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    Ceramic reactor for use with corrosive supercritical fluids (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1798-1799 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420632
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  • 131
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    Influence of membrane walls on particle dynamics in a circulating fluidized bed (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 3550-3553 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421225
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  • 132
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    Molar mass distribution and solubility modeling of asphaltenes (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 3533-3543 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Attempts to model asphaltene solubility with Scatchard-Hildebrand theory were hampered by uncertainty in molar volume and solubility parameter distribution within the asphaltenes. By considering asphaltenes as a series of polyaromatic hydrocarbons with randomly distributed associated functional groups, molar volume and solubility parameter distributions are calculated from experimental measurements of molar mass and density. The molar mass distribution of Athabasca asphaltenes is determined from interfacial tension and vapor pressure osmometry measurements together with plasma desorption mass spectrometry determinations from the literature. Asphaltene desnities are calculated indirectly from mixtures of known concentration of asphaltene in toluene. Asphaltene density, molar volume, and solubility parameter are correlated with molar mass. Solid-liquid equilibrium calculations based on solubility theory and the asphaltene property correlations successfully predict experimental data for both the precipitation point and the amount of precipitated asphaltenes in toluene-hexane solvent mixtures.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690421222
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    Influence of time on crystal attrition in a stirred vessel (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 3554-3558 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421226
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  • 134
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    Critical coagulation concentration of counterions (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 3567-3570 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421229
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  • 135
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    Effect of heterogeneous mechanisms during reburning of nitrogen oxide (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1968-1976 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: NO reduction through heterogeneous mechanisms is a major concern when coal or lignite is used as reburning fuel. Reburning was simulated in an alumina flow reactor operated with a synthetic flue gas at a stoichiometric ratio of 1.1, at 1,100°C and with a residence time of approximately 0.2 s. Reburning fuels used include methane, one bituminous coal, two lignites, chars derived from the bituminous coal and two lignites, and the bituminous coal char impregnated with CaO. Reburning with chars indicates that heterogeneous mechanisms are more important than homogeneous mechanisms when lignites are used. This high reactivity renders lignite char an even more effective reburning fuel than the parent lignite, while char from the bituminous coal produces little activities at stoichiometric ratios above 0.75. Bituminous coal char impregnated with CaO demonstrates higher NO reduction efficiency than the original char. Effects of SR on NO reductions imply that oxygen atoms, required for the NO and HCN conversions in homogeneous mechanisms, are not required in heterogeneous mechanisms. In fact, they inhibit the surface NO reduction. The first-level kinetic analysis indicates that the surface area is not the only contributor to a remarkable increase in NO reduction of lignite char, and chars of different origins seem to follow different mechanisms or to have different controlling steps in the overall reaction scheme.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690420717
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    Surface fractality of wood charcoals through small-angle X-ray scattering (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2014-2024 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Geometrical properties of the pore-solid interfaces of devolatilized charcoals from the pyrolysis of fuel woods in a bench-scale fluidized-bed reactor were investigated through small-angle X-ray scattering. Specifically, surface morphological features of the interfaces were characterized by a single parameter indicative of the degree of surface roughness, that is, the surface fractal dimension, dSF, at various retention times. The surface fractal dimensions of the original wood samples prior to devolatilization were approximately identical for all species within the range between 2.00 and 2.15, over a length scale from 55 to 600 Å, and those for the respective charcoals from these wood samples were influenced to different degrees by the retention time, τ, in the reactor. The dSF's of the mesopores of charcoals of all the species attained maxima at a value of τ equal to 35 s and decreased subsequently with an increase in τ. The analysis of this unexpected trend was facilitated by the values of the mean radii of gyration of the pores, estimated through the Guinier plots. The results imply that when the retention time of the charcoals in the reactor is prolonged, the mechanism of pore enlargement and smoothening of the interfaces can play a dominant role in altering the surface morphology and thereby influence significantly the kinetics of chemical reactions in heterogeneous porous systems.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690420722
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    Effective viscosities in thin ionic micellar liquid films (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2005-2013 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Thin liquid films stabilized by surfactants above the critical micelle concentration exhibit stratification or stepwise dynamic thinning. A continuum hydrodynamic model is outlined for stepwise film thinning that incorporates equilibrium micellar structuring through self-consistent oscillatory disjoining pressures and effective viscosities. Effective viscosities as functions of thickness are evaluated with an extension of the local average density model, considering dilute colloidal suspension shear viscosities and solvent effects. To establish local shear viscosities, structured DFT micellar profiles, coarse-grained densities, and disjoining pressure are used. Ionic micelles and other colloidal systems with repulsive interactions show structured effective viscosities that are generally less than the corresponding homogeneous solution shear viscosity, bounded by the pure solvent viscosity and that of the bulk micellar solution. For 0.1 and 0.2-M sodium dodecylsulfate micellar solutions, the effective viscosities are less than 5 and 10%, respectively, below the homogeneous fluid viscosity, except at small thicknesses, indicating that the micellar film thins faster than a pure water film of the same thickness.Calculated thinning curves closely resemble experimental observations in the stepwise thinning behavior, displaying decreasing slopes and increased step durations at later times. Despite the micellar structuring within the film, the ionic micelles do not contribute appreciably to the viscous resistance of the thinning film. Rather, Reynolds' film thinning is obeyed, with the equilibrium oscillatory disjoining pressures driving the stepwise dynamics. The shear viscosity of the ionic micellar film is well approximated by that of the bulk solution.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420721
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    Perturbation analysis of Thomas and Windle's model of Case II transport (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2025-2035 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Thomas and Windle's model of Case II transport is analyzed for a semiinfinite medium by a singular perturbation technique. Two adjacent boundary layers separate equilibrated and dry regions. A thin boundary layer of width ∼ O(M-1/2/ln M), where M (≫1) dictates how rapidly the mixture's viscosity decays with liquid concentration, sits next to the equilibrated outer left region. Here, quasi-steady diffusion balances relaxation. A thicker intermediate layer of width ∼ O(M-1/2) separates the lefthand boundary layer and the dry outer region on the right, where both relaxation and unsteady diffusion participate in the transport. Matching the solutions at leading order specifies the moving front's speed, v: v ∼ M1/2. The analysis indicates that relaxation significantly affects the nearly dry region just ahead of the moving front. This disagrees with the widely accepted view that ordinary diffusion dominates in the nearly dry righthand region. Approximating that ordinary diffusion dominates in this region leads to a stepexponential concentration profile at the front and a simple analytical solution for the front speed, v with the correct M scaling. This approximate result accurately predicts the values of v determined by direct numerical solutions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420723
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  • 139
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    Solvatochromic characterization of the liquid phase in liquid - supercritical CO2 mixtures (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2047-2056 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The solvatochromic dye phenol blue (N, N-dimethylindoaniline) is used to characterize the solvent strength (polarity) of the saturated liquid phase in a series of solvent-carbon dioxide binary mixtures. Data were obtained at 35 and 55°C and at pressures up to ∼70 bar. Five solvents were investigated - acetone, cyclohexane, methanol, THF, and toluene. The polarity of the liquid phase decreases significantly with increasing pressure due to the increasing carbon dioxide content of this phase at equilibrium. For example, the polarity of acetone saturated with carbon dioxide at 35°C and ∼60 bar is equivalent to the polarity of pure cyclohexane at ambient pressure. The local environment about the dye is significantly richer in the polar liquid component than the bulk composition would indicate. The degree of enrichment reflects concentration effects at low pressure, and both concentration and pressure effects at high pressure where the mixtures are highly compressible. The NRTL model of Renon and Prausnitz is able to predict these local compositions with reasonable accuracy except at CO2-rich conditions where compressibility effects are important.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690420725
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  • 140
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    Improved thermodynamic parameters for prediction of structure H hydrate equilibria (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2036-2046 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An improved set of all the thermodynamic and molecular properties required for the prediction of the existing 20 systems of Structure H (sH) hydrate phase equilibrium data is presented. The statistical thermodynamics model was based on the van der Waals and Platteeuw theory, and the spherical core Kihara potential was used for guest-water interactions. Optimized Kihara parameters and reference thermodynamic properties were derived from experimental data of over 20 sH hydrate forming systems. The model could fit all the existing sH hydrate data within an accuracy of ± 6%. Inhibitor predictions were also shown to fit recent data with no adjustable parameters. The feasibility of using hydrate cage occupancies to derive refined Kihara parameters of the guest molecules was investigated. Possible existence of sH hydrates at cryogenic temperatures was also established based on the model.
    Additional Material: 20 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690420724
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  • 141
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    Gas flow dynamics in hollow-fiber membranes (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2094-2099 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420732
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    Masthead (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996) 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420801
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  • 143
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    Single-pellet dynamics for the soil organic matter effect on dichloromethane sorption (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2090-2093 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420731
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  • 144
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    Boundary effects on the sedimentation and hindered diffusion of charged particles (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2101-2111 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A general formalism is developed to examine the sedimentation of a charged particle in a bounded system at small Peclet numbers and small particle-surface potentials. The excess viscous force is evaluated using a generalized form of the Lorentz reciprocal theorem, eliminating the need to calculate the detailed fluid flow around the charged particle. Specific calculations are provided for the sedimentation of a charged sphere in a concentric (uncharged) spherical cavity. Boundary interactions increase the magnitude of the excess force at small Debye lengths, with the opposite effect seen at very large Debye lengths. A general solution is presented for the sedimentation velocity for an arbitrary particle in both unbounded and bounded systems in the limit of very thin double layers. The excess force under these conditions is proportional to the square of the Debye length, with the proportionality constant being a function of the detailed system geometry. These results provide important insights into the transport of charged particles in porous membranes and chromatographic materials.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690420802
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  • 145
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    Convective wall-to-suspension heat transfer in circulating fluidized bed risers (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2112-2117 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mechanistic model, which incorporates recent findings on the fluid dynamics in the riser of the circulating fluidized bed (CFB), is developed for predicting the suspension-to-wall heat-transfer coefficient in the riser. It is assumed that heat transfer between the gas-particle suspension and the riser wall takes place by the contact of both particle packets and an emulsion phase on the wall. A characteristic length (L), that is, a sliding distance of the emulsion phase along the heat-transfer surface, is introduced in the model, enabling the effect of the length of heat-transfer surface to be evaluated. It is found that the heat-transfer coefficient decreases with increasing L, but becomes increasingly insensitive to L when L is larger than 1 m. Agreement between model prediction and measurement is encouraging over a range of operating conditions, heat-transfer surface length, and riser diameters.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420803
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    Dynamic rectification of data via recurrent neural nets and the extended Kalman filter (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2225-2239 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The presence of autocorrelated measurement errors and/or measurement bias in process measurements poses serious problems in the rectification of data taken from dynamic processes. The proposed procedure to resolve these problems involves the use of recurrent neural networks (RNN) and the extended Kalman filter (EKF). By interpreting RNNs within a nonlinear state-space context, a state-augmented EKF can be used to optimally estimate both the states of the RNNs and noise and bias models. RNN models can be identified off-line and utilized for data rectification within the extended Kalman filter in process environments in which badly autocorrelated measurement errors exist in the data. The same technique is also used to estimate measurement bias present in both process input and output variables. This approach has the advantage that models developed from “first principles” are not required and that rectification can be performed solely on the basis of the contaminated dynamic data.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420812
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    Optimal design of dynamic systems under uncertainty (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2251-2272 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fundamental developments of a unified process design framework for obtaining integrated process and control systems design, which are economically optimal and can cope with parametric uncertainty and process disturbances, are described. Based on a dynamic mathematical model describing the process, including path constraints, interior and end-point constraints, a model that describes uncertain parameters and time-varying disturbances (for example, a probability distributions or lower/upper bounds), and a set of process design and control alternatives (together with a set of control objectives and types of controllers), the problem is posed as a mixed-integer stochastic optimal control formulation. An iterative decomposition algorithm proposed alternates between the solution of a multiperiod “design” subproblem, determining the process structure and design together with a suitable control structure (and its design characteristics) to satisfy a set of “critical” parameters/periods (for uncertainty disturbance) over time, and a time-varying feasibility analysis step, which identifies a new set of critical parameters for fixed design and control. Two examples are detailed, a mixing-tank problem to show the analytical steps of the procedure, and a ternary distillation design problem (featuring a rigorous tray-by-tray distillation model) to demonstrate the potential of the novel approach to reach solutions with significant cost savings over sequential techniques.
    Additional Material: 19 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690420814
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    Phase equilibria for aqueous protein/polyelectrolyte gel systems (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2335-2353 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A molecular-thermodynamic analysis is directed toward predicting the partitioning of aqueous proteins into charged hydrogels. This analysis takes into account size exclusion by the network, electrostatic interactions, and the osmotic-pressure difference between a hydrogel and its surrounding solution. Electrostatic interactions in the polyelectrolyte gel can be described by Debye - Hückel theory, or the Mean Spherical Approximation, or Katchalsky's cell model for polyelectrolyte solutions. The cell model gives best agreement with experimental partition coefficients for cytochrome c. The quasi-electrostatic potential difference between a gel and its surrounding solution demonstrates how the electrostatic contribution to the protein partition coefficient depends on protein charge, gel-charge density, and solution ionic strength. Finally, a qualitative guide is presented for design of a polyelectrolyte gel such that it exhibits specified swelling and partitioning properties.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/aic.690420823
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    Estimation of gas wall shear stress in horizontal stratified gas-liquid pipe flow (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2369-2373 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420826
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    Masthead (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996) 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421001
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  • 151
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    Simple empirical nonlinear model for temperature-based high-purity distillation columns (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2692-2697 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420931
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  • 152
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    Polymer surfaces from physics to technology. By Fabio Garbassi, Macro Morra, and Ernesto Occhiello, Wiley, New York, 1994, 462 pp., $95.00 (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2699-2700 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420934
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  • 153
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    Group-contribution lattice-fluid EOS: Prediction of LLE in polymer solutions (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 3223-3230 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The modified group-contribution lattice-fluid equation of state (GCLF-EOS) was applied to predict liquid-liquid equilibria (LLE) in polymer solutions. The modified GCLF-EOS is a group-contribution form of the equation of state by Panayiotou and Vera based on the lattice-hole theory. Group contributions for the interaction energy and reference volume were developed based only on the saturated vapor pressures and liquid densities of low-molecular-weight compounds. For a mixture, group contributions for the binary interaction parameter were developed from the binary vapor-liquid equilibria of low-molecular-weight compounds. This modified GCLF-EOS model can be applied to predict LLE behavior in polymer solutions with the same group-contribution parameters as used for predicting the vapor-liquid equilibria. The only input required for the model is the structure of the molecules in terms of their functional groups.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421123
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  • 154
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    Radiative transfer in photocatalytic systems (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 532-537 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Radiation absorption at the surface of catalytic particles is the initial step of photocatalytic oxidation reactions currently considered for their potential effectiveness in the treatment of polluted water with traces of highly toxic organics. Owing to the presence of catalyst particles within the fluid phase, the radiation field within a photocatalytic reactor results from the absorption and scattering within the participating medium. An annular reactor with a coaxial central lamp was considered, and the resulting 2-D radiation field was analyzed using a Monte Carlo technique to solve the radiative transfer equation. Results are discussed based on the relevant optical parameters, and a heuristic is derived for the design and rating of a photocatalytic reactor. To exploit the reaction volume effectively, the order of magnitude of the optical thickness should be close to unity, and for a given value of the absorption coefficient the catalyst with the lowest albedo should be selected; however, a precise evaluation of the phase function is not crucial to a relable representation of the radiation field.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420222
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  • 155
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    Extension of a generalized quartic equation of state to pure polar fluids (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 562-570 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A generalized four-parameter quartic equation of state (EOS) proposed by Shah and coworkers (1992, 1994) was extended to polar fluids. To use the new generalized quartic EOS for polar fluids, only four characteristic properties of the pure compound are required - critical temperature, critical volume, acentric factor, and dipole moment. For nonpolar fluids, the previous equation is recovered and its superior performance for nonpolar fluids is retained. A new set of coefficients for polar fluids for the EOS was determined from multiproperty regressions using literature data for various physical and thermodynamic experimental properties of 30 pure compounds. These regressed coefficients, which are functions of the critical temperature, critical pressure, acentric factor, and the dipole moment of the fluid, were generalized. The accuracy of this equation of state is evaluated with the new set of regressed coefficients to predict thermodynamic properties of pure polar compounds, including vapor pressure, density, residual enthalpy, enthalpy of vaporization, and second virial coefficient. The capability and accuracy of this quartic equation of state are also compared with the well-known Peng-Robinson EOS.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420225
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  • 156
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    Solvation thermodynamics of gas solubility at sub- and near-critical conditions (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 571-584 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The recently developed formalism for describing the solute-induced effect in dilute near-critical mixtures is extended to fluids composed of anisotropic molecules through the statistical mechanical interpretation of the derivative (∂P/∂x2)T,p∞ whose critical value is the Krichevskii parameter.Rigorous expressions for Henry's constant and the solute distribution factor along the orthobaric curve are derived in terms of the volumetric and entropic solute-induced local effects, and the quasi-linear behavior of their orthobaric density dependence away from the solvent's critical point is rationalized.The formalism is illustrated with integral equation calculations of the orthobaric density dependence of several solvation thermodynamic quantities for an infinitely dilute volatile solute in near-critical solutions of hard-sphere Yukawa fluids.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420226
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  • 157
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    Generalized method for prediction of saturated liquid volumes using Van der Waals volumes (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 595-598 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420228
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  • 158
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    Transport of n-paraffins in zeolite T (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 68-86 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mass transport of n-heptane, n-nonane, and n-dodecane in zeolite T was studied using a gravimetric uptake technique. The sigmoidal shape of the uptake curves indicated the existence of a nondiffusional resistance in the transport process. To compute the transport parameters, an approach based on the temporal moments of the uptake curves was developed. A model involving an external resistance dependent on the local slope of the sorption isotherm best represented the data. No evidence of the “window effect” reported by Gorring was found. The measured diffusivities decrease with chain length, while the activation energies remain essentially constant. Both resistances (diffusional and nondiffusional) depend strongly on lattice loading, and their relative contributions for the transport time change as saturation is approached.
    Additional Material: 28 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420108
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  • 159
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    Fluidization characteristics of biobone particles used for biocatalysts (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 87-95 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Liquid-solid fluidization characteristics of irregularly shaped Biobone particles were studied in a fluidized bioreactor column 2.35 m high and 0.1 m dia. The wet biobone particles had a density of 1,890 kg/m3. Two size ranges were studied: 1.70-2.36 mm and 1.25-2.36 mm. The Biobone is a natural cheap material composed of collagen, which is a strong protein structure, embedded with microcrystals of hydroxyapatite and calcium phosphate, and it is an excellent matrix of commercial importance used for the immobilization of enzymes, whole cells and other biocatalysts. Fluidization characteristics of Biobone particles, which include measurements of pressure drops, holdups, minimum fluidization velocities, particle entrainment, and residence time distributions at different water superficial velocities, are reported. Because of the highly irregular shape of Biobone particles, new fluidization behavior was observed, which was much different from the fluidization behavior of spherical particles reported in the literature. A new channeling index, Ic, is proposed to quantify the channeling characteristics of fluidized Biobone particles, and a new parameter, α, was developed to distinguish the transition between fixed and fluidized states of the Biobone particles.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420109
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  • 160
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    Journal review. Azeotropic distillation (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 96-130 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recent and ongoing research in the distillation of nonideal mixtures is reviewed focusing on advances in the methodologies for the synthesis, design, analysis and control of separation sequences involving homogeneous and heterogeneous azeotropic towers. Maps of residue curves and distillation lines are examined, as well as geometric methods for the synthesis and design of separation sequences, trends in the steady-state and dynamic analysis of homogeneous and heterogeneous towers, the nonlinear behavior of these towers, and strategies for their control.Emphasis is placed on the methods of computing all of the azeotropes associated with a multicomponent mixture, on the features that distinguish azeotropic distillations from their zeotropic counterparts, on the potential for steady-state multiplicity, and on the existence of maximum and minimum reflux bounds. Important considerations in the selection of entrainers are examined. For the synthesis of separation trains, when determining the feasible product compositions, the graphical methods are clarified, especially the conditions under which distillation boundaries can be crossed and bounding strategies under finite reflux. The application of geometric theory to locate the fixed points, at minimum reflux, is reviewed in connection with homotopy-continuation algorithms for this purpose. The use of homotopy-continuation algorithms, especially for the steady-state simulation of heterogeneous azeotropic distillations, is justified. Methods for phase stability analysis are reviewed in connection with the location of real bifurcation points at phase transitions, an important feature of algorithms for the dynamic simulation of heterogeneous azeotropic distillations.
    Additional Material: 47 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420110
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  • 161
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    Effects of isomorphic compounds on the purity and morphology of L-isoleucine crystals (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 147-153 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: L-Isoleucine and the isomorphic amino acids L-leucine and L-valine serve as a model system in the examination of the effects of impurities on the purity and morphology of crystals recovered from batch crystallizations. Factors are determined that influence crystal purity and, concomitantly, crystal size and shape. Characteristics of the L-isoleucine crystal are determined by X-ray analysis and compare favorably with the literature. These and literature characteristics of L-leucine and L-valine are used in simulations to evaluate possible mechanisms by which lattice substitutions with impurities lead to size and morphological changes.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420112
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  • 162
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    Recuperative parametric pumping in adsorptive membranes (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 131-146 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recuperative parametric pumping in adsorptive membranes, a cyclical adsorptive separation process, can lead to two distinct mechanisms of separation: rejection and preferential transport. During rejection, the adsorptive membrane rejects an adsorbing solute while permitting the transport of nonadsorbing solutes. During preferential transport the reverse occurs; the adsorptive membrane selectively transports an adsorbing solute while preventing the transport of nonadsorbing solutes. Switching from rejection to preferential transport can be accomplished by merely decreasing the ratio of the stroke volume (cyclical volume of solution pumped into and out of the membrane) to the membrane void volume. Preferential transport, earlier called an “inverse separation,” results from the adsorbing solute crossing over from an adsorbing to a desorbing region in the interior of the membrane and is governed by the shape of the equilibrium isotherms and by process variables. In experiments with lysozyme and a membrane chromatography cartridge, selectivities obtained by preferential transport were on the order of 5 and agreed with theoretical predictions. Theoretical predictions suggest that to further improve separation by preferential transport, experiments need to be conducted on low dispersion membranes (Pe 〉 104) and that both rejection and preferential transport can lead to continuous concentrated streams of the adsorbing solutes.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420111
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  • 163
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    Thermal frequency response method for the study of mass-transfer kinetics in adsorbents (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 700-712 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The frequency response method measuring the temperature and pressure of an adsorbent sample determines the mass- and heat-transfer kinetics in adsorbents, especially in zeolites. The temperature of the sample (large crystals or monolayers of pellets) is measured by infrared detection. The main aspects of the in-phase and out-of-phase functions as given by an analytical bidispersed model are described. They depend on characteristic times related to kinetic paprameters. Experimental results on adsorption of water on NaX zeolite (crystals or pellets) show that this method allows heat transfer to be very clearly delineated from mass-transfer modes and the separation of different mass-transfer modes. For a bidispersed sample, macro- and microporous mass-transfer parameters may be obtained with the same sample. Results on a contaminated 5A zeolite-propane system show the presence of mass-transfer resistance at the pellet surface. The infrared temperature measurement associated with the frequency response appears to be powerful in determining kinetic adsorption, and gives more information than the pressure measurement.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420311
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  • 164
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    Reverse micellar mass-transfer processes: Spray column extraction of lysozyme (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 713-726 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Protein partitioning kinetics was measured for the semibatch extraction of lysozyme in a laboratory-scale, liquid-liquid spray column. The organic, isooctane phase contained reverse micelles formed from the anionic surfactant, sodium di-2-ethylhexyl sulfosuccinate. For the extraction of protein from aqueous to reverse micellar phases, experiments were performed over a range of dispersed-phase flow rates for cases of the organic- or aqueous-phase dispersion. The influence of aqueous-phase pH and ionic strength, which influence electrostatic interactions between protein and reverse micelles, was also investigated. Results were interpreted in terms of a two-film model of mass transfer. The nature of the dispersed pahse could significantly influence the partitioning kinetics, while study of the droplet hydrodynamics suggested that stagnant drops were formed regardless of which phase was dispersed. Literature correlations for describing the droplet-formation process and droplet hydrodynamics predicted measured values satisfactorily. Attempts wer also made to predict overall mass-transfer coefficients based on existing correlations describing mass transfer during droplet formation, free rise (or fall), and coalescene. Predicted values of KL were 2-10 times greater than measured values, probably because of large concentrations of surfactant used to formulate the reverse micelle phases. This approach did, however, provide detailed information on the quantity of protein transferred during the successive processes of droplet formation, free rise (or fall) and coalescence.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420312
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  • 165
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    New discretization procedure for the agglomeration equation (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 727-741 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new discretization procedure for the agglomeration equation is presented. The intrinsic problems caused by discretization of the particle-size distribution are mitigated by using proper probability functions. Thus, the new discretized equation predicts the same total number of particles as its continuous counterpart and guarantees conservation of mass. This general method can correctly predict any two properties simultaneously and is not limited to number and mass. Simulation results with various agglomeration kernels show that the new method provides significant improvements over the conventional discretization method. Furthermore, the new method allows the user to choose equal-size intervals or geometric-size intervals with any geometric ratio to cover the particle-size range. In addition to flexibility, the latter feature leads to better accuracy in particle-size distribution predictions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420313
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  • 166
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    Gage control of film and sheet-forming processes (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 753-766 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new methodology for gage control of sheet and film processes is presented. A linear process model is developed that is capable of describing many of the interesting features of the process, including a noisy and moving gage sensor, significant process noise, strong coupling between the gage in different lanes, constraints on the actuators, and significant time delay between the actuators and the sensor. An automatic control of this process given this model form is designed. Novel features of the controller are that it can contend with information from a moving sensor and handle hard constraints on the actuators. Control performance and robustness to noise are demonstrated favorably via simulations.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420315
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  • 167
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    Process synthesis under uncertainty: A penalty function approach (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 742-752 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: With the growing environmental concern, it is necessary to improve process simulation and develop design tools to account for environmental factors in the synthesis of large-scale chemical processes. A major obstacle in tackling this problem is uncertainties in some of the technical and economic parameters, which lead to uncertainties in design, plant performance, and cost estimates. Further, a conceptual process design involves the identification of an optimal flowsheet structure from many alternatives stituting the “superstructure.” Synthesis and optimization of large-scale processes involving uncertainties often require considerable computational effort. A novel algorithm presented here is based on simulated annealing for the process synthesis of large-scale flowsheets having several configurations and considers uncertainties in the process design systematically. This new “stochastic annealing algorithm,” provides an efficient approach to stochastic synthesis problems by incorporating a penalty term in the objective function and balances the trade-off between accuracy and efficiency based on the annealing temperature. It has been used to study a benchmark synthesis problem in the HDA process. Savings of up to 80% in CPU time has been achieved without significant loss of solution precision with stochastic annealing, compared to simulated annealing with a fixed sample size. It can be applied to analyze efficiently any complex process flowsheet and provide valuable insights into process feasibility based on optimal design, plant performance, and uncertainty issues.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420314
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  • 168
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    Process identification using discrete wavelet transforms: Design of prefilters (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 777-790 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Most advanced control applications rely on good dynamic process models. The performance of the control system depends on the accuracy of the model used. Typically, such models are developed by conducting off-line identification experiments on the process. These identification experiments often result in input-output data with small output signal-to-noise ratio, and using these data results in inaccurate model parameter estimates. Prefilters are used to separate useful information from the noise in the input-output data and to improve parameter estimates. A systematic design procedure for selecting a prefilter using discrete wavelet transforms is presented. The design procedure provides explicit information on the compromises in prefilter design, interpreted in terms of parameter variance and bias. The prefilter design procedure is then applied to identify a second-order output error model.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420317
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  • 169
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    Closed-loop identification of a continuous crystallization process (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 767-776 
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    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Identification of low-order linear multiinput/multiouput models can lead to accurate descriptions of the dynamic behavior of a continuous crystallization process. While open-loop experiments exhibit an oscillating crystal size distribution, improved experimental conditions can be established through stabilization of the process with a simple single-loop feedback controller. The resulting closed-loop identification problem is studied using low-order linear multivariable input-output models. Two closed-loop identification methods are applied, one of which was recently introduced to provide accurate approximate models in general closed-loop process configurations. Identification and validation data are obtained from an evaporative pilot crystallizer, and the identified models are validated in terms of time- and frequency-domain responses. A fourth-order, three-input three-output model is shown to describe accurately the process dynamics. The results are compared with a linearized and reduced first-principles model.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420316
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    Scanning force microscopy of gypsum dissolution and crystal growth (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 232-238 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dissolution and crystal growth on the (010) cleavage surface of mineral gypsum have been studied by scanning force microscopy, which allows observation of surfaces while they are in contact with aqueous solutions. Etch pits formed on the (010) surface in contact with solutions undersaturated with respect to gypsum are oriented in relation to the [001] zone axis. Edges parallel to [001] are stable or move only slowly. Edges parallel to [100] and [101] move more rapidly. Crystal growth by migration of step edges is observed in contact with supersaturated solutions. The inhibition of crystal growth by phosphonate produces gross changes in the texture of steps and terraces.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420119
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  • 171
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    Aggregate behavior and lumped kinetics of many reactions in backmixed and plug-flow reactors (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 214-231 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The long-time behavior of a reaction mixture containing infinitely many species in isothermal continuous stirred tank reactors (CSTRs) is analyzed and contrasted with that in a plug-flow reactor (PFR). The reaction kinetics considered are irreversible first-order, irreversible coupled pseudo first-order, and reversible first-order. Asymptotic lumped kinetics for the mixture as a whole are developed as a function of feed properties and reactor type. Such lumped kinetics in many cases are of the power law form, with the exponent for a CSTR being lower than that for a PFR. Conditions under which non-power-law kinetics arise are given. Due to the wide spread of reactor residence times, the mixture in CSTRs admits a much richer variety of asymptotic possibilities than in the PFR. The results uncover some behavioral differences and relationships between CSTRs and a PFR for converting complex mixtures such as petroleum distillates or coal liquids.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420118
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  • 172
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    Sedimentation of noncolloidal bidisperse suspensions (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 271-276 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420125
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  • 173
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    Wavy-to-slug flow transition in slightly inclined gas-liquid pipe flow (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 901-909 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A process-engineering model is presented for the stratified-wavy-to-intermittent (SW-I) flow-pattern transition in slightly inclined gas-liquid pipe flow. The main parameter for predicting (in) stability of wavy flow in inclined pipes is the average liquid holdup, which was found to reach a maximum, critical value at flow-pattern transition. Observed values of the critical liquid holdup vary between 0.07 and 0.42, depending on pipe diameter, angle of inclination and transport properties of the gas-liquid system. Measurements were performed in transparent glass pipes of 26- and 51-mm dia., at ten angles of inclination (0.1° ≤ β ≤ 6.0°), using air/water and air/tetradecane (n-C14H30) systems at atmospheric pressure. Flow-pattern maps are presented for selected angles of inclination, showing excellent agreement between predicted and observed flow-pattern boundaries.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420402
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  • 174
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    Random walks in prefractal porous media (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 921-926 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Random walks are used to examine dispersion between miscible fluids in one-dimensional, prefractal porous medium. Mixing in such media is anomalous and several nonlocal theories have been proposed to describe this non-Fickian characteristic. This work simulates dispersion via a random walk in a prefractal media by incorporation local and spatially nonlocal effects and compares the results with laboratory experiments. Results suggest that nonlocal models fit experimental data better than local models.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420404
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  • 175
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    Wall effects on the sedimentation velocity of suspensions in viscous flow (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 927-931 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The sedimentation velocity of multiparticle suspensions was investigated experimentally for cases where the column wall is likely to have a nonnegligible effect. The experiments demonstrate that the container wall diameter influeces the falling velocity only for dilute systems, which is in contrast with a widely used, established empirical relationship.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420405
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  • 176
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    Absorption-induced separations in oscillatory liquid chromatography (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 940-952 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It has been shown that small-amplitude oscillations can augment the diffusional flux across a cylindrical tube by several orders of magnitude through Taylor-Aris dispersion phenomena (Aris, 1960). This enhancement in mass transport is selective for species with different molecular diffusion coefficients. This article shows that by coupling fluid oscillations with a reversible absorption in a stationary phase, the transport of species, which have similar molecular diffusivities but different affinities for the stationary phase, can be enhanced selectively. We developed analytical and asymptotic solutions to the enhancement of mass transfer as a result of the interaction between reversible absorption and fluid oscillations in a cylindrical tube. These results were qualitatively confirmed by experiments with a model system. For purely oscillatory flow, the maximum selectivity (the ratio of the fluxes of the species to be separated) achievable is 4.4 for solute species with widely different affinities for the stationary phase. The superposition of a small-amplitude steady backflow, however, can greatly increase the selectivity, but at the expense of throughput. Analysis shows that this technique may offer improvements relative to conventional liquid membrane separations, if the solute affinities for the stationary phase do not greatly differ or if a thick membrane is required for stability.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420407
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  • 177
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    Permeability of gigaporous particles (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 932-939 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The volumetric flow rate of liquid and gas through small gigaporous particles was measured by a new method that isolates single particles in a test apparatus. To our knowledge, this is the first direct confirmation of flow through gigaporous particles made at pressure drops experienced during normal operation. High-performance liquid chromatography particles from 30 to 50 μm in diameter, previously reported to exhibit convection-enhanced intraparticle mass transfer, were studied. Using a CFD model of the test system, the permeability of individual particles was determined from the pressure-drop-flow-rate relationship. The average measured permeability of the particles studied is 7.89 × 10-15 m2 with no dependence on particle size. This is 4 to 17 times greater than values calculated from models currently used to estimate the permeability of these kinds of particles. No other experimentally measured values of permeability have been reported for particles of this size. The results of this study might imply that the intraparticle structure does not behave like a bed of uniformly packed microspheres, but rather as an inhomogeneous assemblage of microparticles. The measured permeability values offer the possibility of developing better models of the intraparticle flow field under normal operating conditions. Knowledge of the intraparticle flow field is an important step in deriving predictive models of convective mass transfer in these types of particles.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420406
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  • 178
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    Determining porosity profiles during filtration and expression of sewage sludge by NMR imaging (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 953-959 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The formation of a filter cake during mechanical dewatering (filtration and expression) of sludge is studied using one-dimensional nuclear magnetic resonance (NMR) imaging of porosity profiles. The experiments clearly showed the formation of a porosity gradient during filtration and the disappearing of this gradient during expression, forming a cake with a uniform porosity. This technique makes it possible to investigate the material behavior of the porous medium, which is needed before any model calculations can be performed. The results indicate that NMR imaging is useful in nondestructive monitoring of the filtration and expression process of sludge.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420408
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  • 179
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    Prediction of sedimentation and consolidation of fine tails (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 960-972 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sedimentation and consolidation of suspensions of fine particles were analyzed by integrating experimental measurement of properties in a centrifuge with a comprehensive numerical model. The yield stress and settling velocity for tailings from tar sands extraction were determined experimentally as a function of the volume fraction of solids. The evaluated state functions were used to simulate batch settling and consolidation, and the results compare well with long-term settling tube tests. This approach is very attractive where gravity sedimentation may take many years, and it allows prediction of the rate of clear water production, total time for sedimentation and consolidation, and the maximum concentration of solids.Scaling of the sedimentation between centrifuge and field conditions is discussed. Conversion of permeability-void ratio relationships from geotechnical experiments to state functions of hindered settling velocity is demonstrated, allowing the use of data derived from a variety of experimental techniques.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420409
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  • 180
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    Solving linear diffusion-reaction networks in porous catalyst particles using BEM (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 383-390 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Multiple diffusion reactions are frequently encountered in the modeling of heterogeneous catalytic reactors. Obtaining an accurate estimate of the yield and selectivity in such reactions is crucial for an optimal design of reactors. Due to the inadequacy of analytical techniques in handling nonuniform catalyst shapes and mixed boundary conditions, numerical techniques are often employed to compute these design parameters. Among other numerical techniques, the boundary element method (BEM) is a superior method to solve linear diffusion reaction problems. The integral nature of the BEM formulation allows for boundary-only discretization of the particle, thus reducing the computer execution time and the data preparation effort. A boundary element algorithm is developed to solve a network of linear diffusion reactions in porous catalyst particles in two dimensions. For this purpose, a matrix of fundamental solutions is defined and derived. The developed algorithm is applied to complex reaction networks to obtain the yield of intermediates for nonregular catalyst shapes and nonuniform boundary conditions. The method can be used as a design tool to study particle scale modeling in detail and can be incorporated into an overall reactor model.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420208
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  • 181
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    Separation of branched hexane isomers using zeolite molecular sieves (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 405-408 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A range of small, medium and large pore zeolite, and their modified forms are studied for their ability to separate di- from monobranched isomers of hexane. The separation studies are carried out using high-temperature (250-350°C) gas chromatography. Beta(H,Ba) is found to be the most effective separator of 2,3-dimethylbutane and 3-methyl-pentane and is therefore studied for its sorption capacities toward the two hexane isomers.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420210
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  • 182
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    Generalized modular representation framework for process synthesis (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1010-1032 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A generalized modeling framework for process synthesis alternatives is proposed, based on fundamental mass/heat-transfer principles. A multipurpose mass/heat-transfer module is introduced as the building block of the framework, whereas basic block-superstructure rules (such as splitting, mixing, and bypassing) are used to develop a systematic representation of process units and process structures, conventional or not. Process synthesis procedures are explored within this modeling framework, where synthesis alternatives are not postulated as process unit networks, but explored simultaneously without predefining synthesis schemes, as combinations of mass/heat-exchange stream matches. The representation potential of this framework is illustrated with examples from unit operations, whereas synthesis example problems are presented to show the broad range of process alternatives that can be modeled, identified, and optimized.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420413
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  • 183
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    Hollow-fiber membrane-based rapid pressure swing absorption (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 409-421 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel gas purification technique called rapid pressure swing absorption (RAPSAB) was developed by integrating the best features of membrane contacting, gas-liquid absorption, and pressure swing adsorption (PSA). In this cyclic separation process, a well-packed microporous hydrophobic hollow-fiber module was used to achieve nondispersive gas absorption from a high-pressure feed gas into a stationary absorbent liquid on the module shell side during a certain part of the cycle followed by desorption of absorbed gases from the liquid in the rest of the cycle. The total cycle time varies between 20 s and upwards. Separation of mixtures of N2 and CO2 (around 10%) where CO2 is the impurity to be removed was studied using absorbent liquids such as pure water and a 19.5% aqueous solution of diethanolamine (DEA). Three RAPSAB cycles studied differ in the absorption part. Virtually pure N2 streams were obtained with DEA as absorbent demonstrating the capability of bulk separation to very high levels of purification. Numerical models developed predict the extent of purification for pure water and the DEA solution for one of the simpler cycles. Model simulations describe the observed behavior well.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420211
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  • 184
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    Crystallization of phenanthrene from toluene with carbon dioxide by the GAS process (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 431-439 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The crystallization of phenanthrene from toluene with carbon dioxide as the antisolvent gas is described. In the GAS process, a pressurized gas is dissolved into a liquid solvent, where it causes a volumetric expansion and lowers the solubility of the solute. Theoretical models are presented for the liquid-phase expansion and the solubility as a function of pressure and temperature. The Nývlt theory for batch crystallization is adapted to predict the pressure profile in the crystallizer needed to maintain a constant supersaturation and growth rate. Generation of seeds is accomplished via a pressure pulse at the saturation pressure. The average particle size of the phenanthrene could be varied from 160 to 540 μm. Creation of seeds doubles the particle size and reduces the coefficient of variation significantly. The residual amount of toluene in the crystals without treatment is approximately 70 ppm. The particles are agglomerates of phenanthrene crystals.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420213
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  • 185
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    On-line parameter estimation in a high-pressure low-density polyethylene tubular reactor (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 440-454 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The high throughput and operating cost of the reactor provide the economic incentive in considering the on-line optimization of the LDPE tubular reactor. For an on-line optimization procedure it is crucial to develop a flexible and adaptive on-line parameter estimator, which based on the appropriate measurements from the reactor will adjust certain key model parameters so that the model can capture the actual reactor operation and reliably be used for the real-time optimization of the reactor performance. Various issues involved in developing the on-line estimator for such applications as the mathematical modeling of the reactor, the selection of the adjustable model parameters and reactor measurements, the decomposition of the problem according to the characteristic time constants of various disturbances, and the efficient and robust solution of the mathematical problem are discussed. The tools developed were successfully used on an EXXON high-pressure LDPE tubular reactor. Results from the numerical experiments that are compared with scaled data from a real reactor show that the estimated temperature profiles agree remarkably with those observed at various phases of the reactor operation.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420214
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  • 186
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    Predictive control of quality in batch polymerization using hybrid ANN models (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 455-465 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two issues involving the methodology used for on-line control of product quality in batch manufacturing processes are addressed: the generation of fast, data-driven process models and the use of such process models for on-line feedback control of product quality. The methodology is investigated using the example of the control of dispersity and molecular weight distribution in a batch reactor for emulsion polymerization of vinyl acetate. An artifical neural network (ANN) is used as a model to predict the quality as a function of the manipulated variables and on-line measurements. This model is constructed using an augmented dataset that integrates experimental information and knowledge from a mathematical model. The proposed model is compared with other types such as a theoretical model whose key parameters are fitted to experimental data. The hybrid ANN is superior to the parameter-fitting approach for this case. Experimental and simulation studies confirm the advantage of using the proposed model and the predictive control algorithm.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420215
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  • 187
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    Disturbance rejection with bounded control action: Loop-shaping methodology (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 466-476 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Suppressing the influence of external disturbances on a process is the most common objective of a controller in a chemical plant. A control system that can keep the controlled variables at or near their set point and the manipulated variables lower than their prespecified maximum bounds in the face of load disturbances is wanted. A method is presented to design controllers with disturbance rejection specifications and limits over the control energy. This methodology is based on a special strategy to shape the structured singular value of a closed-loop transfer function matrix.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420216
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  • 188
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    Compression of chemical process data by functional approximation and feature extraction (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 477-492 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Effective utilization of measured process data requires efficient techniques for their compact storage and retrieval, as well as for extracting information on the process operation. Techniques for the on-line compression of process data were developed based on their contribution in time and in frequency using the theory of wavelets. Existing techniques for compression via wavelets and wavelet packets are inconvenient for on-line compression and are best suited for stationary signals. These methods were extended to the on-line decomposition and compression of nonstationary signals via time-varying wavelet packets. Various criteria for the selection of the best time-varying wavelet packet coefficients are derived. Explicit relationships among the compression ratio, local and global errors of approximation, and features in the signal were derived and used for efficient compression. Extensive case studies on industrial data demonstrate the superior performance of wavelet-based techniques as compared to existing piecewise linear techniques.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420217
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  • 189
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    Neural network architecture for process control based on the RTRL algorithm (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 493-502 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Neural-network-based control schemes are generally designed by replacing standard elements of the classic control schemes by feedforward neural networks. The introduction of discrete time recurrent networks, which are inherently dynamic systems, into those schemes can simplify the design of neural controllers. The concept of applying recurrent networks in indirect adaptive control schemes is described. A combined network cluster consisting of the control network and the model network is constructed to allow the use of the real-time recurrent learning algorithm. To demonstrate the feasibility of the method two simulation examples are presented.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420218
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  • 190
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    Startup strategy design and safeguarding of industrial adiabatic tubular reactor systems (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 503-515 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The safeguarding methodology of chemical plants is usually based on controlling the instantaneous values of process state variables within a certain operating window, the process being brought to shutdown when operating constraints are exceeded. This method does not necessarily prevent chemical reactors suffering from a runaway during dynamic operations because (a) excessive amounts of unreacted chemicals can still accumulate in the process, and (b) no means are provided to the operating personnel to identify hazardous process deviations. A model-based startup and safeguarding procedure is developed for an industrial adiabatic tubular reactor to improve process safety during startup. The trajectories of manipulated variables are calculated by minimizing the amount of one of the main reactants in the reactor effuent. It is concluded that proper control of the initial reactor temperature profile is critical for a safe startup while the impact of other manipulated variables is relatively smaller than that of the initial reactor temperature profile.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420219
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  • 191
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    One-sided single-pellet technique for adsorption and intraparticle diffusion (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 516-523 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The one-sided single-pellet dynamic technique introduced in this article is shown to be a very effective and simple method for the analysis of adsorption and diffusion in porous solids. Moment expressions are presented for reversible and irreversible adsorption processes. Since the adsorption equilibrium constant is the only unknown parameter in the first moment expression, this parameter can be evaluated from a single set of pulse-response experiments. This technique to evaluate the adsorption equilibrium constant is illustrated using ethylbromide as tracer. It is also shown that for a very strongly adsorbing tracer, such as 1,2-dichloroethane in soil, modified moment expressions derived with a semiinfinite boundary condition are necessary unless a criterion developed in this work is satisfied.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420220
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  • 192
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    Coke effect in mass transport and morphology of Pt-Al2O3 and Ni-Mo-Al2O3 catalysts (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 524-531 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of high levels of coke deposit on catalyst properties and mass transport through the pores space was studied using commercial catalysts, Pt-Al2O3 and Ni-Mo-Al2O3. Changes in porosity, pore-size distribution and internal surface area of several aged catalysts were compared to those of fresh catalyst. Effective diffusivity was also measured by pulse chromatography. For Pt-Al2O3, which shows a high initial porosity (0.93) and a relative high mean pore radius (300 Å), catalyst properties remain unchanged while coke content increased. For the Ni-Mo-Al2O3 catalyst (with initial porosity of 0.53 and mean pore radius of 50 Å), however, with an increase of 15% in coke content, isolated void regions appear, and porosity, internal surface area and effective diffusivity decrease sharply. Pore and stochastic models were used to interpret the effective diffusivity experimentally measured. A structural parameter in each case, tortuosity factor in pore models, and coordination number in the percolation model were calculated. When coke produces significant changes in catalyst morphology, the tortuosity factor almost doubles its initial value for a coke content of 20%. On the contrary, the percolation model seems to predict changes accurately in porosity, mass trasport coefficient, and an isolated prosity growing from the coordination number matched for a fresh catalyst.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420221
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  • 193
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    Letter to the editor (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1195-1195 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420435
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  • 194
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    Adsorption from binary immiscible liquid mixture (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1191-1194 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420434
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  • 195
    Electronic Resource
    Electronic Resource
    Electrochemical process engineering. By F. Goodridge and K. Scott, Plenum Press, New York, 1995, 312 pp., $59.50 (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1195-1195 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420436
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  • 196
    Electronic Resource
    Electronic Resource
    Multiphase flow and fluidization: Continuum and kinetic theory descriptions. By Dimitri Gidaspow, Academic Press, New York, 1994, 467 pp., $69.50 (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1197-1198 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420438
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  • 197
    Electronic Resource
    Electronic Resource
    A first course in electrochemical engineering. By Frank Walsh, Electrochemical Consultancy, Hants, England, 1993, 381 pp., $45.00 (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1195-1197 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420437
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  • 198
    Electronic Resource
    Electronic Resource
    Flow and transport in porous media and fractured rock. By Muhammad Sahimi, VCH-Verlagsgesellschaft mbH, Weinheim, Germany, 1995, 482 pp., $65.00 (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1198-1199 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420439
    Library Location Call Number Volume/Issue/Year Availability
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  • 199
    Electronic Resource
    Electronic Resource
    Polymers and neutron scattering. By Julia S. Higgins and Henri C. Benoit, Oxford University Press, Oxford, England, 1994, 436 pp., $98.00 (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1200-1200 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420441
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  • 200
    Electronic Resource
    Electronic Resource
    Atomization of dilute polyisobutylene/mineral oil solutions (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1201-1212 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Atomization experiments, motivated by the need to suppress misting of machining oils, were conducted on dilute solutions of polyisobutylene (PIB) in mineral oil using a coaxial air blast atomizer and an optical (Fraunhofer diffraction) particle sizer. Polymer concentrations (0.1 to 1.0 kg/m3) and molecular weight (1.0 to 2.2 million) were varied to determine their effects on aerosol drop-size distributions. The pure oil and PIB - oil solutions were atomized at air/liquid mass ratios near 10 and atomizing air velocities of 150-270 m/s, producing droplet-size distributions with mass mean diameters (MMD) in the range of 7-15 μm for the pure oil. Under identical atomization conditions, the MMDs of PIB solutions were 20-200% higher than pure oil. These observed increases in MMD correspond to significant reductions in the fraction of droplets falling below 5 μm in diameter that constitute the misting problem in industrial machining applications. Observed effects of PIB on atomization are ascribed to the viscoelastic properties of PIB - oil solutions as characterized by the elongational viscosity ηE. This relationship is examined by correlating the change in MMD caused by PIB addition with the stress-dependent elongational viscosity of PIB-oil solutions as predicted by the FENE-P dumbbell kinetic theory. The increase in MMD due to PIB varies linearly with the predicted ηE at constant atomization tensile stress.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420502
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