Reaction-Engineering Analysis

Neurock, M., A Computational Chemical Reaction Engineering Analysis of the Molecular Pathways and Kinetics of Complex Heavy Hydrocarbon Reaction Systems, Ph.D. Dissertation, Univ. of Delaware, 1992. 

In this section we discuss the use of the tanks-in-series model to describe nonideal reactors and calculate conversion. We will analyze the RTD to determine tlie number of ideal tanks in series that will give approximately the same RTD as the nonideal reactor. Next we will apply the reaction engineering analysis developed in Chapters 1 through 4 to calculate conversion. We are first going to develop the RTD equation for three tanks in series (Figure 14.1) and then generalize to n reactors in series to derive an equation that gives the number of tanks in series that best fits the RTD data. 

KeUe, R., Laufer, B., Brunzema, C., Weuster-Botz, D., Kramer, R., Wandrey, C., 1996. Reaction engineering analysis of L-lysine transport by Corynebacterium glutamicum. Biotechnology and Bioengineering 51 (1), 40-50. 

When the kinetics are unknown, still-useful information can be obtained by finding equilibrium compositions at fixed temperature or adiabatically, or at some specified approach to the adiabatic temperature, say within 25°C (45°F) of it. Such calculations require only an input of the components of the feed and produc ts and their thermodynamic properties, not their stoichiometric relations, and are based on Gibbs energy minimization. Computer programs appear, for instance, in Smith and Missen Chemical Reaction Equilibrium Analysis Theory and Algorithms, Wiley, 1982), but the problem often is laborious enough to warrant use of one of the several available commercial services and their data banks. Several simpler cases with specified stoichiometries are solved by Walas Phase Equilibiia in Chemical Engineering, Butterworths, 1985). 

Chemical themiodynamics provides tlie answer to tlie first question however, it provides information about tlie second. Reaction rates fall witliin tlie domain of chemical kinetics and are treated later in tliis section. Both equilibrium and kinetic effects must be considered in an overall engineering analysis of a chemical reaction. 

In section 11.3 we saw how a classical reaction engineering approach45 can been used to model both electrochemical promotion and metal support interactions. The analysis shows that the magnitude of the effect depends on three dimensionless numbers, II, J and Op (Table 11.3) which dictate the actual value of the promotional effectiveness factor. 

The time that a molecule spends in a reactive system will affect its probability of reacting and the measurement, interpretation, and modeling of residence time distributions are important aspects of chemical reaction engineering. Part of the inspiration for residence time theory came from the black box analysis techniques used by electrical engineers to study circuits. These are stimulus-response or input-output methods where a system is disturbed and its response to the disturbance is measured. The measured response, when properly interpreted, is used to predict the response of the system to other inputs. For residence time measurements, an inert tracer is injected at the inlet to the reactor, and the tracer concentration is measured at the outlet. The injection is carried out in a standardized way to allow easy interpretation of the results, which can then be used to make predictions. Predictions include the dynamic response of the system to arbitrary tracer inputs. More important, however, are the predictions of the steady-state yield of reactions in continuous-flow systems. All this can be done without opening the black box. 

Regenass, W., 1978, ACS Syinpos. Ser. 65, Chemical Reaction Engineering, Houston, 37. Regenass, W., 1980, Proc. Vlth hit. Conf. on Thermal Analysis, Bayreuth, July, 561. 

Froment, G. F. and Bischoff, K. B. Chemical Reactor Analysis and Design, 2nd edn (Wiley, 1990). Levenspiel, O. Chemical Reaction Engineering, 3rd edn (Wiley, 1998). 

Froment, G. F., Analysis and Design of Fixed Bed Catalytic Reactors, in Chemical Reaction Engineering, Adv. Chem. Series, 109 (1), American Chemical Society, Washington, D.C., 1972. 

Chemical reaction engineering (CRE) is concerned with the rational design and/or analysis of performance of chemical reactors. What is a chemical reactor, and what does its rational design involve A chemical reactor is a device in which change in com-... 

RONALD W. MISSEN is Professor Emeritus (Chemical Engineering) at the University of Toronto. He received his B.Sc, and M.Sc. in chemical engineering from Queen s University, Kingston, Ontario, and his Ph.D. in physical chemistry from the University of Cambridge, England. He is the co-author of CHEMICAL REACTION EQUILIBRIUM ANALYSIS, and has authored or co-authored about f 50 research articles. He is a fellow of the Chemical Institute of Canada and the... 

It is the purpose of this article to present in its entirety one of the early applications of reaction engineering, which was well under way in 1952 before the name Reaction Engineering was even coined. We will describe the laboratory kinetic experiments, the diffusional analysis, the integration of these phenomena into a mathematical process model, its field testing and validation, and subsequent use in process design, modification, control, and optimization. 

The engineering analysis and design of these operations addresses questions which are different than those addressed in connection with the shaping operations. This is illustrated in Fig. 1 which is a flow sheet, cited by Nichols and Kheradi (1982), for the continuous conversion of latex in the manufacture of acrylonitrile-butadiene-styrene (ABS). In this process three of the nonshaping operations are shown (1) a chemical reaction (coagulation) (2) a liquid-liquid extraction operation which involves a molten polymer and water and (3) a vapor-liquid stripping operation which involves the removal of a volatile component from the molten polymer. The analysis and design around the devolatilization section, for example, would deal with such questions as how the exit concentration of... 

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