Semibatch Reactor Mole Balances

From this general mole balance equation we can develop the design equations for the various types of industrial reactors batch, semibatch, and continuous-flow. Upon, evaluation of these equations we cau determine the time (batch) or reactor volume (continuous-flow) necessary to convert a specified amount of the reactants to products. 

When using an ordinary differential equation (ODE) solver such as POLYMATH or MATLAB, it is usually easier to leave the mole balances, rate laws, and concentrations as separate equations rather than combining them into a single equation as we did to obtain an analytical solution. Writing She equations separately leaves it to the computer to combine them and produce a solution. The formulations for a packed-bed reactor with pressure drop and a semibatch reactor are given below for two elementary reactions. 

Writing the Semibatch Reactor Equations in Terms of the Number of Moles. We can also solve semibatch reactor problems by leaving the mole balance equations in terms of the number of moles of each species (i.e., N, ... 

We divide the chapter into two parts Part 1 Mote Balances in Terms of Conversion, and Part 2 Mole Balances in Terms of Concentration, C,. and Molar Flow Rates, F,." In Pan 1, we will concentrate on batch reactors, CSTRs, and PFRs where conversion is the preferred measure of a reaction s progress for single reactions. In Part 2. we will analyze membrane reactors, the startup of a CSTR. and semibatch reactors, which are most easily analyzed using concentration and molar How rates as the variables rather than conversion. We will again use mole balances in terms of these variables (Q. f,) for multiple reactors in Chapter 6. 

For a semibatch reactor, a balance on moles of monomer 1 can be written as... 

In Chapter 5 we discussed the unsteady operation of one type of reactor, the batch reactor. In this section, we discuss two other aspects of unsteady operation startup of a CSTR and of semibatch reactors. First, the startup of a CSTR is examined to determine the time necessary to reach steady-state operation [see Figure 6-4(a)]. and then semibatch reactors are discussed. In each of these cases, we are interested in predicting the concentration and conversion as a function of time. Closed-form analytical solutions to the differential equations arising from the mole balance of these reaction types can be obtained only for zero- and hrst-order reactions. ODE solvers must be used for other reaction orders. 

R6,1B Semthatch Reactor Balances in Terms of Number of Moles R6.1C Semibatch Reactor Balance in Terms of Conversion R6.1D E(/uilihrium Conversion The Practical Side... 

Derive the mole balance relation for each functional group for semibatch reactors from which acetaldehyde, ethylene glycol, methanol, and water are continuously flashing. 

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