摘要:

AbstractAn automated Taylor dispersion apparatus, designed to operate from 298 to 573 K and 101 to 3,450 kPa (14.7 to 500 psia), was used to measure diffusion coefficients at infinite dilution for the solutesn‐octane,n‐decane,n‐dodecane,n‐tetradecane, andn‐hexadecane in the solventsn‐heptane andn‐dodecane. Dodecane viscosity and density also were measured at all conditions. Various predictive theories are tested in light of the new data, and a correlation based on the data at high temperature and pressure is presented. The data are well represented by a free‐volume expression of the form\documentclass{article}\pagestyle{empty}\begin{document}$ D_{AB} /\sqrt T = \beta \,(V - V_D) $\end{document}. The data given here extend the available data base for alkane/alkane diffusion by 100 to 200 K, and allow evaluation of predictive theory over an extended range

ISSN:0001-1541    

DOI:10.1002/aic.690330602

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractGlobally convergent homotopy continuation methods have been used successfully to find multiple solutions to systems of nonlinear equations used to model multicomponent, multistage separation processes. However, the solutions were achieved by using a multitude of different starting points. This paper describes a procedure for finding all or some solutions of the nonlinear equation system from just one starting point. A reliable algorithm, which utilizes a deflated decomposition technique to overcome the turning‐point problem, an efficient procedure to estimate step sizes, and variable mapping functions to prevent failure when computing physical properties, is developed to follow the homotopy path. The Jacobian matrix is retained as a special structure in all calculation steps. The algorithm has found, from one starting point, all the real roots of the interlinked separation system studied by Chavez et al. (1986). Two additional examples, including one optimization problem and one constrained nonlinear equation system, are presented to illustrate other applications of the algorith

ISSN:0001-1541    

DOI:10.1002/aic.690330603

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractAn efficient nonlinear programming strategy is presented for integration of heat engines and heat pumps with chemical processes. The strategy utilizes the temperature interval method and shows how to use negative heat deficits to obtain lower cost designs. Two important situations are presented in which the resulting designs are less costly when the heat engines and heat pumps are integrated with temperature intervals having negative heat deficits.

ISSN:0001-1541    

DOI:10.1002/aic.690330604

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractA hydrodynamic model is developed relating the movement of printed circuit panels to solution flow in through‐holes. Qualitative and quantitative model verification is experimentally established. Effects of external gas bubbling on hole solution transport are elucidated. Based on the hydrodynamic model, panel motion criteria for contamination‐free and fast chemical processing are introduced. Limits of mechanical panel movement as a method for processing holes of different geometry with typical wet chemical process baths are addres

ISSN:0001-1541    

DOI:10.1002/aic.690330605

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractVarious numerical approaches have been adopted to solve the single‐stage isothermal flash problem. These approaches result in two classes of methods. The first includes equation‐solving methods that try to solve a nonlinear equation system; the second is based on a minimization of the total Gibbs free energy. Most of these methods may fail to find a solution or may lead to erroneous solutions near critical conditions when an equation of state is applied to both the vapor and liquid phases.New methods for solving the problem are proposed. Combining the simplicity in structure of the conventional successive‐substitution method and the efficiency of some unconstrained minimization algorithms, they all ensure convergence to local minima of the Gibbs free energy. The new methods are compared from the standpoints of computer storage and calculational effort requirements. The performance of these methods is tested on four multicomponent systems taken from literature, and a comparison is made with other published me

ISSN:0001-1541    

DOI:10.1002/aic.690330606

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractPrior experimental study by Haldeman and Botty has demonstrated that catalyst regeneration rates vary with conversion, showing a nearly constant rate of reaction in the early stages of regeneration and falling off rapidly at higher conversion levels. This peculiar reaction behavior calls for explanation in terms of pore structural changes. In this work a mathematical model is developed based on the interaction between catalyst pore structure and coke distribution in the pores. The model is able to associate overall regeneration kinetics with alternative pore‐distributed coke deposition patterns. Results exhibit a slight shallow rate maximum at an intermediate conversion level, in agreement with the prior experimental report. The model makes coke distribution in the pores accessible to experimental determination. The numerical results indicate that among pore structures with the same mean and overall pore volume, a larger variance offers a higher threshold for coke loading; for a given degree of dispersion, a smaller mean allows a higher coke loadin

ISSN:0001-1541    

DOI:10.1002/aic.690330607

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractVessel overpressure behavior during emergency relief venting in both bubbly and churn‐turbulent flow regimes was obtained analytically. The transient predictions are shown to be in good agreement with the more exact numerical integration scheme. The applications of current results in relief vent sizing for both reactor vessels and storage tanks are demonstrated via numerical example

ISSN:0001-1541    

DOI:10.1002/aic.690330608

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractReactant segregation and mixing effects can be represented by a one‐dimensional distribution of alternating reactive liquid layers. This paper reports a theoretical study of the influence of this configuration on the course of three‐component, random block copolymerizations. Two models that follow the interdiffusion of the reacting species and the catalyst are considered. The first employs a lumped competitive‐parallel kinetic scheme to represent the formation of hard and soft segments; the second uses a moment formulation to handle the polymerization. The results are intended for the description of mixing‐activated three‐component polyurethane systems, but conclusions of a general nature are obtained. Several unexpected results are presented regarding the molecular weight buildup and spatial product segregation in the system. In particular, it is established that reactant segregation may severely influence product segregation (layering), the average molecular weight, and the maximum molecular weight

ISSN:0001-1541    

DOI:10.1002/aic.690330609

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractAn analysis of parallelism for modular process flowsheet calculations is given. The central idea is to examine various algorithms that allow one to decouple and decentralize flowsheet calculations for computation in a multiprocessor environment. Specific algorithms are evaluated which make use of quasi‐Newton updates to converge the flowsheet equations. From the analysis presented and example problems solved, it is clear that parallel processing can be used to enhance the computational speed of modular flowsheet calculations. In particular, various formulations of the simultaneous modular approach are analyzed to show how parallelism may be taken advantage of in flowsheet solution

ISSN:0001-1541    

DOI:10.1002/aic.690330610

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractDrops sizes for turbulent dispersion of aqueous solutions in organic liquids were determined and correlated for three types of dispersion devices: small‐diameter tubes, motionless mixer units, and a rotating annular disperser with Couette flow. Empirical correlation based on dimensional analyses were useful for application of these devices to gel‐sphere processes. The results support the Kolmorogoff theory of turbulence as a dispersion mechanism for a range of 104for the rate of energy dissipat

ISSN:0001-1541    

DOI:10.1002/aic.690330611

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY