Batch reactors data analysis methods

The parameters K and V , can readily be determined from batch reactor data by using the integral method of analysis, Dividing both sides of Equation (7-95) by tKJV and rearranging yields... 

Chapter 2 covers the basic principles of chemical kinetics and catalysis and gives a brief introduction on classification and types of chemical reactors. Differential and integral methods of analysis of rate equations for different types of reactions—irreversible and reversible reactions, autocatalytic reactions, elementary and non-elementary reactions, and series and parallel reactions are discussed in detail. Development of rate equations for solid catalysed reactions and enzyme catalysed biochemical reactions are presented. Methods for estimation of kinetic parameters from batch reactor data are explained with a number of illustrative examples and solved problems. 

Advantages and Disadvantages 41 Specific Batch Techniques 42 Data Analysis 46 Flow and Stirred-Flow Methods 46 Advantages and Disadvantages 46 Continuous Flow Method 48 Fluidized Bed Reactors 50 Stirred-Flow Technique 51... 

Propose a generalized rate expression for testing the data. Analysis of rate data by the differential method involves utilizing the entire reaction-rate expression to find reaction order and the rate constant. Since the data have been obtained from a batch reactor, a general rate expression of the following form may be used ... 

Batch reactors are used primarily to determine rate law parameters for homo, geneous reactions. This determination Ls usually achieved by measuring coa centration as a function of time and then using either the differential, integral, or least squares method of data analysis to determine the reaction order, a, and specific reaction rate, k. If some reaction parameter other than concentration i s monitored, such as pressure, the mole bMance must be rewritten in terms of the measured variable (e.g., pressure). 

Outline an experimental procedure and a method of data analysis that will enable one to determine the constants Kj)S, K and k of Illustration 8.4 with a minimum of experimental effort. Assume that D t) measurements were taken at equal time increments (i.e., 0.1, 0.2, 0.3- -h.) Benzene is to be nitrated in a batch reactor with acid composed of 15mol% HNO3, 25mol% H2SO4, and 60mol% H2O. The amount of this acid is to be 10% in excess of the theoretical amount required for 100% conversion, although only 96% conversion is required. The reaction temperature is 40°C, at which the densities are 0.87, 1.20 and 1.60 g/ cm for benzene, nitrobenzene, and the acid mixture, respectively. 

This simple approach was adopted in order to circumvent the complications that are introduced by the fact that the volume of the liquid phase in the reactor varies with time. When the volume of the aqueous growth medium varies during the course of the reaction, an approach based on integration of a proposed rate law is problematic, although numerical integration would be possible. An additional reason for employing the differential approach below is that for rate laws that are other than those of the simple nth-order form (such as a Monod rate expression) a differential method of data analysis is often adequate for preliminary considerations involved in the design of a bioreactor that is intended to operate in a batch mode. 

Tubular flow reactors are also employed to obtain information on the reaction mechanism, particularly for gas phase reactions. Like batch reactors, experimental data can be obtained using a differential or integral reactor and the analysis performed using the differentiation or integration method. 

The integral method of analysis can be used when the available data are in the form of concentration (or fractional conversion) versus time or space time (or V/Fao or W/Fao)-As pointed out earlier in this chapter, this kind of data are obtained when an ideal batch reactor or an ideal plug-flow reactor is used. For these two reactors, use of the integral method avoids the need for numerical or graphical differentiation. 

Within each of the three general approaches toward process synthesis, key decisions are made about the flowsheet design that have a bearing on the operability characteristics of the plant. For example, in a hierarchical procedure (Ref. 6) we will make decisions about whether the plant is batch or continuous, what types of reactors are used, how material is recycled, what methods and sequences of separation are employed, how much energy integration is involved, etc. In a thermodynamic pinch analysis, we typically start with some flowsheet information, but we must then decide what streams or units to include in the analysis, what level of utilities are involved, what thermodynamic targets are used, etc. In an optimization approach, we must decide the scope of the superstructure to use, what physical data to include, what constraints to apply, what disturbances or uncertainties to consider, what objective function to employ, etc (Ref. 7). 

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