摘要:

AbstractThis review article surveys representative literature on enzyme kinetics and engineering published form January 1969 to August 1971. Particlar attention is given to methods of attaching enzymes to solid supports, and to factors, such aspH and temperature, which affect the reaction rate. Recent theories accounting for the high selectivity and high rate of enzyme reactions, calculations taking into consideration the effects of diffusion, methods for analysing kinitic data, and proposals for enzyme reactors are evaluated. Also reviewed are recent methods for extraction of enzymes from cells, procedures for synthesizing enzymes artificailly, and techniques for isolating and purifying enzymes.

ISSN:0001-1541    

DOI:10.1002/aic.690180103

出版商:American Institute of Chemical Engineers    

年代:1972

数据来源: WILEY

摘要:

AbstractThe effect of side‐wall friction on the uniformity of packing of beds in compression‐permeability cells is examined. A large portion of pressure applied to the top of a compressible bad is absorbed in wall friction, resulting in a nonuniformly packed bed. A simplified analysis of wall friction and its effect on porosity and permeability is presented.All experimenters involived in flow through porous media are urged to examine the effects of stress distribution on the structure and uniformity of the packing. In general, compressible beds of small particles will be strongly affected by the wa

ISSN:0001-1541    

DOI:10.1002/aic.690180104

出版商:American Institute of Chemical Engineers    

年代:1972

数据来源: WILEY

摘要:

AbstractThe “complex” method of M. J. Box has been adapted and used to optimize the design of continuous chemical processes. Such a design involves the extremization of a nonlinear objective function subject of nonlinear equality and inequality constraints. The method consists of finding an original feasible “complex” of solutions, eliminating the worst of these by reflection through the controid of those remaining, and repeating until an optimum has been reached. An example of significant complexity has been solved and the results are reported. The method looks quite promising for use in the optimization of chemical process

ISSN:0001-1541    

DOI:10.1002/aic.690180105

出版商:American Institute of Chemical Engineers    

年代:1972

数据来源: WILEY

摘要:

AbstractA general treatment of entry region multicomponent mass transfer between a fully developed turbulent flow and a smooth pipe wall has been developed from a basis first derived by Toor.The couled multicomponent equations were reduced to an equivalent binary system by the method of undetermined constants. Numerical solutions for a forced convection, binary diffusion system involving gas‐phase, nonequimolal diffusion were applied to a ternary system. These solutions have been found to compare well with these authors entry region mass transfer data on a ternary acetone‐methonal‐air mixture and with the earlier analogy theories derived for the case of an infinitely long test section.We conclude that there is a significant interaction in some multicomponent systems, enough that the binary theory can not be satisfactorily applied in the design of multicomponent mass transfer sy

ISSN:0001-1541    

DOI:10.1002/aic.690180106

出版商:American Institute of Chemical Engineers    

年代:1972

数据来源: WILEY

摘要:

AbstractThe effect of solids loading ratio, particle size, and gas Reynolds number on the pressure drop and flow characteristics of a dilute gas‐solid suspension in turbulent pipe flow has been studied experimentally in both vertical and horizontal test sections. Glass beads of 10 to 60μ diameter were used at air Reynolds numbers of 10,000 to 25,000 and solids loading ratios of up to 2.5 Drag reduction was observed in the vertical test section for all of the particles studied, with the 30μ particles yielding a maximum drag reduction of about 75% at a loading ratio of 1.5. In the horizontal test section, drag reduction was observed only with the smallest sized particles, indicating a gravity effect. An explanation of these results based on the particles interacting with the turbulent structure of the gas near the wall has been propo

ISSN:0001-1541    

DOI:10.1002/aic.690180107

出版商:American Institute of Chemical Engineers    

年代:1972

数据来源: WILEY

摘要:

AbstractAn activated diffusion, or site‐hopping, mechanism is used to describe surface diffusion of gases through porous media. This analysis provides a useful and accurate method for correlating data at submonolayer coverages on energetically heterogeneous surfaces. The data needed to use this correlation are surface area and pore structure of the adsorbent, adsorption isotherms at two or more temperatures, and the activation energy for migration. The former quantities are easily determined from Knudsen diffusion and adsorption measurements, while the activation energy can be found from a single permeability measurement. Predictions made in this way show excellent agreement with experimental dat

ISSN:0001-1541    

DOI:10.1002/aic.690180108

出版商:American Institute of Chemical Engineers    

年代:1972

数据来源: WILEY

摘要:

AbstractTheoretical expressions are derived for the fraction of the energy, emitted from a UV lamp, which strikes the reactor wall in systems where a reflecting surface is included. Two geometries used in photoreactors are considered: a cylindrical lamp located at the focus of a superimposed parabolic reflecor. The predicted efficiencies are low, particularly for the elliptical reflector—reactor system, because of the energy that escapes through the ends of the system. Experimentally determined efficiencies for the elliptical type are in reasonable agreement with predicted values, suggesting that the theoretical method may be used for estimating efficiencies for different reactor system

ISSN:0001-1541    

DOI:10.1002/aic.690180109

出版商:American Institute of Chemical Engineers    

年代:1972

数据来源: WILEY

摘要:

AbstractThe sorption isotherms are reported for the β‐soluble anhydrite form of calcium sulfate (Drierite) exposed to moist air at one atmosphere total pressure and 90, 100, 125, 150, 175, and 200°F. A concentration‐temperature coordinate has been identified which when plotted against the amount sorbed caused all isotherms to collapse into a single sorption therm. The latter has been fit by a three‐term expression based on a combination of sorption theories. A graphical comparison is made between a curve calculated from the analytical expression and actual experimental datum points.Curve fitting was done by machine and involved minimizing the square of the deviations. Maximum deviations up to 4% are experienced in the high range. In the low range these tend to increase but so do the experimental

ISSN:0001-1541    

DOI:10.1002/aic.690180110

出版商:American Institute of Chemical Engineers    

年代:1972

数据来源: WILEY

摘要:

AbstractThe phenomenon of flow attachment to solid surfaces, occurring with both liquids and gases, is the long‐known though inadequately understood Coanda effect.A flow visualization study was made using a birefringent milling yellow dye solutions flowing over a deflection surface consisting of flat plates. A two‐dimensional flow channel with transparent side walls was used. Photographic observations of the development of the Coanda effect reveal the method of flow attachment and confirm a number of literature predictions. One of the most interesting of these phenomena is the existence of a well defined mixing region along the deflection surface.A simplified model of the flow field has been proposed in order to described the mechanism governing the Coanda effect. The model is supported by experimental data consisting of pressure profiles obtained along the deflection surface and secondary flow entrainment measureme

ISSN:0001-1541    

DOI:10.1002/aic.690180111

出版商:American Institute of Chemical Engineers    

年代:1972

数据来源: WILEY

摘要:

AbstractRemoval of the exothermic heat of chemical reactons by autorefrigeration (vaporization of a liquid phase) is frequently used in continuous and batch chemical reactors. The vapor thus generated is usually liquified in a condenser and the condensate returned to the reactor.This paper studies the effects of the formation of an inert gas by‐product on the stability and control of batch autorefrigerated reactors.Stability is shown to be strongly influenced by the production of these inerts because their buildup in the condenser reduces heat removal capacity. Inert buildup can be reduced by venting, but excessive venting results in a loss of not only inerts but also of the volatile components in the system. This leads to higher reactor temperaturs, faster reaction rates and instability.Digital simulation of a numerical example illustrates the effects of various parameter

ISSN:0001-1541    

DOI:10.1002/aic.690180112

出版商:American Institute of Chemical Engineers    

年代:1972

数据来源: WILEY