Reaction, Separation and Recycle Systems for Continuous Processes - Summary

10 REACTION, SEPARATION AND RECYCLE SYSTEMS FOR CONTINUOUS PROCESSES - SUMMARY 

The use of excess reactants, diluents or heat carriers in the reactor design has a significant effect on the flowsheet recycle structure. Sometimes the recycling of unwanted byproduct to the reactor can inhibit its formation at source. If this can be achieved, it improves the overall usage of raw materials and reduces effluent disposal problems. However, the recycling results in an increase of some costs. 

When a mixture in a reactor effluent contains components with a wide range of volatilities, then a partial condensation from the vapor phase followed by a simple phase split can often produce a good separation. If the vapor from such a phase split is difficult to condense, then further separation needs to be carried out in a vapor separation process such as a membrane. The liquid from the phase split can be sent to a liquid separation unit such as distillation. 

The process yield is an important measure of both raw materials efficiency and environmental impact. 

Interactions between the reactor and the rest of the process are extremely important. Reactor conversion is the most significant optimization variable, since it tends to influence most operations through the process. When a purge is used to remove impurities from the process, the concentration in the recycle is another important optimization variable, again influencing operations throughout the process. 

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