Separation flowsheets, computer program

This is the fun (and frustration) of chemical reaction engineering. While thermodynamics, mass and heat transfer, and separations can be said to be finished subjects for many engineering apphcations, we have to reexamine every new reaction system from first principles. You can find data and construct process flowsheets for separation units using sophisticated computer programs such as ASPEN, but for the chemical reactors in a process these programs are not much help unless you give the program the kinetics or assume equihhrium yields. 

Thompson and King (1972) presented a computer program to invent separation system flowsheets based entirely on simple separators. The program is entirely heuristic, is very fast when it works, but has a problem with cycling and thus not always terminating with an answer. 

In recent years a considerable amount of literature has appeared in chemical engineering journals on the subject of process synthesis. Nishida et al. reviewed the current state of the art as it applies to cheiiucal processes. If process synthesis methodology were developed fully, one could invoke a computer program which, with minimal input, would select not only the separation method of choice but also would determine how the various unit operations should be connected together to form the entire flowsheet. At the present time, however, process synthesis methodology for separation processes is in the earty stages of research. 

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