Dynamic Simulation of the Plug-Flow Tubular Reactor

5 Dynamic Simulation of the Plug-Flow Tubular Reactor 

The coupling of the component and energy balance equations in the modelling of non-isothermal tubular reactors can often lead to numerical difficulties, especially in solutions of steady-state behaviour. In these cases, a dynamic digital simulation approach can often be advantageous as a method of determining the steady-state variations in concentration and temperature, with respect to reactor length. The full form of the dynamic model equations are used in this approach, and these are solved up to the final steady-state condition, at which condition 

This is shown below in Fig. 4.11, where segment n, with volume AV, is identified by its midpoint concentration C n and midpoint temperature Tn- The procedure again follows very closely that of Franks (1967). 

The concentration of reactant entering segment n, from segment n-1, is approximated by the average of the concentrations in the two segments and is given by 

Similarly, the concentration of reactant leaving segment n, and entering segment n+1, is approximated by 

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