The fixed bed reactor model requires information about the reactor, fluid, and catalyst. The pictures below show the input assumed for this example.
Since most of the reaction was conducted in the CSTR, there is no need to cool the fixed bed reactor. Thus, I have specified an adiabatic reactor.
A tube diameter has been specified even though the adiabatic reactor diameter will be larger. You will see below why this tube diameter is needed.
We now have enough information to compute the adiabatic reactor diameter.
The thermal conductivity is for a catalyst particle, NOT for a bulk bed of catalyst. This parameter is used in the correlation for the radial thermal dispersion coefficient.
The reactor model also needs the following integration parameters:
My fixed bed reactor model can be used for both adiabatic and non-adiabatic reactors. Due to the finite difference scheme (i.e. the hopscotch method) for solving the PDE, NR must be at least 4 which means there are 5 radial positions. This practice is not as efficient as using an ODE with only axial positions, but it makes it very convenient to switch reactor types.
All of the above parameters are defined on the whiteboard of Mathcad prior to the call of the process simulation program. Should the the process have more than one fixed bed reactor, then the parameters for each would be specified using names that identify the reactor..1,2 etc.
In addition, the wall temperature is required. For an adiabatic case, any value may be supplied in the argument list. Reference temperature and pressure are required for computation of dimensionless temperatures. Inlet temperature and pressure are obtained within the routine.
Next: conversion of the original reactor model for use in a process simulation loop.