摘要:

AbstractPreparative, multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular sorbent bed with fixed multiple feed points and fixed product withdrawal locations. The cation exchange separation of copper, nickel, and two cobalt complexes has been extensively used to study the effects of rotation rate, eluent rate, bed loading, and column size on separation performance. Experimental results have been compared with three theoretical models: plate theory, an analytical solution which incorporates multicomponent Langmuir isotherms, and an extension of the analytical solution to include dispersion effects.

ISSN:0001-1541    

DOI:10.1002/aic.690300502

出版商:American Institute of Chemical Engineers    

年代:1984

数据来源: WILEY

摘要:

AbstractMass transfer coefficients for the growth and the dissolution of potassium alum and sodium thiosulfate in a laboratory‐scale fluidized‐bed apparatus were determined and correlated in a form of the Frössling equation. The surface reaction rate for potassium alum was found to be dependent onthe crystal

ISSN:0001-1541    

DOI:10.1002/aic.690300503

出版商:American Institute of Chemical Engineers    

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper demonstrates how a recently developed observer for time delay systems may be used to estimate needed state variables for implementation of multivariable time delay compensation. The general results are illustrated by an example of a multireactor plant in which only one reactor concentration can be measured. The observer worked well in simulation for both multivarible PID control and multidelay compensated PID control and allowed both schemes to function with estimated state variables in the feedback loop.

ISSN:0001-1541    

DOI:10.1002/aic.690300504

出版商:American Institute of Chemical Engineers    

年代:1984

数据来源: WILEY

摘要:

AbstractIn a system that is close to chemical equilibrium, the relaxation of each elementary step toward equilibrium obeys the linear laws of nonequilibrium thermodynamics. For a series reaction in which the concentration of the intermediate species are low or do not change with time, the relaxation can be characterized by one time constant, which can be associated with an overall equilibrium exchange rate for the overall reaction. The relationship between the overall equilibrium exchange rate and the equilibrium exchange rates of the individual steps is analogous to that between the overall conductance and the individual conductances of a network of electrical resistors in series. A numerical example is presented to show the range of validity of this relationship. Finally, a condition for the determinability of exchange rates is presented. Exchange rates are independently determinable if and only if the determinant of the matrix, whose elements are made up of squares of the inner products of the vectors that are made up of the stoichiometric coefficients of the species in the reactions, is non‐zer

ISSN:0001-1541    

DOI:10.1002/aic.690300505

出版商:American Institute of Chemical Engineers    

年代:1984

数据来源: WILEY

摘要:

AbstractA semitheoretical method has been established for superimposing the residual thermodynamic properties of pure methane and of pure water over wide ranges of pressure (0.01 to 1,000 MPa) and temperature (triple point to twice the critical temperature). Using reasonable mixing rules with two binary parameters, this superposition also gives mixture properties, including high‐pressure vapor‐liquid equilib

ISSN:0001-1541    

DOI:10.1002/aic.690300506

出版商:American Institute of Chemical Engineers    

年代:1984

数据来源: WILEY

摘要:

AbstractPrimary causes of deactivation of hydrodesulfurization catalysts are partial poisoning of the interior pore surface and pore‐mouth plugging by deposition of metals from organo‐metallic compounds in the reactor feed. A model is developed to account for both causes of deactivation. It can be used to predict which occurs first: complete surface poisoning or pore‐mouth plugging. Equations are formulated for catalyst activity as a function of time for demetallization and also for desulfurization. The results depend upon particle geometry and geometry of deposited species, Thiele moduli for demetallization and desulfurization, and relative rates of desulfurization on fresh and partially poisoned catalytic surfaces. The treatment is for a single, isothermal catalyst par

ISSN:0001-1541    

DOI:10.1002/aic.690300507

出版商:American Institute of Chemical Engineers    

年代:1984

数据来源: WILEY

摘要:

AbstractPirt's model for microbial growth and product formation are reparameterized to obtain multiresponse models with common parameters. The dependent variables in the models are related through the available electron and carbon balance constraints. Covariance adjustment is used to reduce the growth model to a unit variate linear model with covariates. Therefore, standard multiple regression programs can be used to obtain combined point and interval estimates of true biomass energetic yield, true product yield and maintenance coefficient. This approach may yield “better” estimates than the maximum likelihood approach when an appropriately selected subset of covariates is used. Nonlinear estimation procedures are also considered; these procedures are efficient with few responses; however, as the number of responses per observation increase, they may require a lot of computing time. For illustration several data from the biochemical engineering literature are analyzed by the proposed meth

ISSN:0001-1541    

DOI:10.1002/aic.690300508

出版商:American Institute of Chemical Engineers    

年代:1984

数据来源: WILEY

摘要:

AbstractA film model is presented for the analysis of mass transfer to a rotating hemispherical electrode when sinusoidal alternating current (AC) together with direct current (DC) are flowing across the electrode surface. The concentration of a diffusing ion is separated into two independent components: a constant DC component and a periodic AC component. The DC concentration is obtained by solving the steady‐state convective mass transport equation with the perturbation method. The periodic AC concentration distribution is analyzed by the solution to the one‐dimensional transient diffusion equation based on the concept of Nernst diffusion layer. The limiting AC current densities corresponding to a zero surface concentration of a reactive ion are investigated for various DC current densities and AC frequencies. The resulting periodic concentration overpotential wave and its phase shift with respect to the applied AC are examined. A comparison with a previous rigorous model indicates that the film model is a good approximation to the mass transfer calculation in the regimes of a dimensionless AC frequencyK= (ω/Ω)Sc1/3greater than 2 and less than

ISSN:0001-1541    

DOI:10.1002/aic.690300509

出版商:American Institute of Chemical Engineers    

年代:1984

数据来源: WILEY

摘要:

AbstractAn experimental study has been made for laminar mass transfer to a rotating disk and a rotating hemispherical electrode when sinusoidal alternating current (AC) together with direct current (DC) are flowing across the electrode/electrolyte interface. A resistor‐capacitor circuit was used to measure the phase shift between the applied AC and the resulting periodical concentration overpotential. The limiting AC current density corresponding to a zero instantaneous surface concentration was determined as a function of AC frequency and DC current density. The experimental data agreed with the theoretical calculations in a regime of a dimensionless AC frequencyK= (ω/Ω)Sc1/3greater than 1 and less than

ISSN:0001-1541    

DOI:10.1002/aic.690300510

出版商:American Institute of Chemical Engineers    

年代:1984

数据来源: WILEY

摘要:

AbstractSimple, efficient and noniterative algorithms are developed for the calculation of the dynamics of continuous countercurrent processes described by hyperbolic differential equations. The algorithms are derived using the method of characteristics and are particularly useful for either general quadratic or hyperbolic isotherms such as the Langmuir isotherm. The use of characteristic coordinates for the numerical solution avoids accumulating errors that would arise from computations based on a rectangular grid of real time and space coordinates.The proposed methods can provide an efficient framework for extension to transport processes with general nonlinear rate expressions. The algorithms and methods initially derived for simple models can be extended to more complex systems such as countercurrent flow with accumulating stationary phases and response to distributed disturbances.The application of the algorithm and methods to a number of countercurrent mass and heat transfer processes will be illustrated in Part II, where the accuracy and efficiency of the proposed methods will also be demonstrated by comparison to available analytic solutions. An example demonstrating the extension of the method to a system with complex coupled boundary conditions will also be discussed.

ISSN:0001-1541    

DOI:10.1002/aic.690300511

出版商:American Institute of Chemical Engineers    

年代:1984

数据来源: WILEY