Design Structure for Isothermal Reactors

If the rate of reaction is not given explicitly as a function of conversion, we must proceed to level where the rate law must be determined by either finding it in books or journals or by determining it experimentally in the laboratory. Techniques for obtaining and analyzing rate data to determine the reaction order and rate constant are presented in Chapter 5. After the rate law has been established, one has only to use stoichiometry (level ) together with the conditions of the system (e.g.. constant volume, temperature) to express concentration as a function of conversion. 

For liquid-phase reactions and for gas-phase reactions with no pressure drop (F = Pq), one can combine the information in levels and , to express the rate of reaction as a function of conversion and arrive at level . It is now possible to detemiine either the time or reactor volume necessary to achieve the desired conversion by substituting the relationship linking conversion and rate of reaction into the appropriate design equation (level ). 

For gas-phase reactions in packed beds where there is a pressure drop, we need to proceed to level to evaluate the pressure ratio (F / in the concentration term using the Ergun equation (Section 4,5). In level , w e combine the equations for pressure drop in level w ith the infomiation in levels and to proceed to level where the equations are then evaluated in the appropriate manner (i.e.. analytically using a table of integrals, or numerically using an ODE. solver). Although this structure emphasize.s the determination of a reaction time or reactor volume for a. specified conversion, it can also readily be used for other types of reactor calculations, such as determining the conversion for a specified volume. Different manipulations can be performed in level to answer the different types of questions mentioned here. 

Rate law. choose the iireveisible first-order reaction 

From mole balance From rate law I From sloichiomeirv 

Apply mole balance to specific reactors to arrive at the design equations  

Q Evaluate the algebraic (CSTR) or integral (tubular, batch) equations either numerically or analytically to determine the reactor volume, processing time, or conversion 

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The development of practical methods [56] for the systematic design of new oscillating reactions in continuous stirred tank reactors (CSTR) lead to the discovery of several dozens of different isothermal oscillating systems, including the CIMA reaction [57]. This reaction is one of the very few to also exhibit transient oscillatory behavior in batch conditions. This and the fact that it does not exhibit marked excitability character like the well-known Belousov-Zhabotinsky reaction [5], lead us to select the CIMA reaction for systematic research on stationary spatial structures in open spatial reactors [14]. 

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