Simple Control of Highly Exothermic Reactions

The major challenge with semibatch processes is to design a feedrate control system which will maintain the desired operating temperature and avoid an undesired reagent buildup or "induction" effect. We have solved this problem by using a computerized model reactor to test a strategy based upon starting at the desired temperature, placing the vessel under full cooling, and maintaining the temperature by the addition of the other reactant. Addition rate control was provided by a simple on-off algorithm. Scaleup of the addition system resulted in a simple design which interfaces with existing pneumatic instrumentation. Three examples of varying chemistries are presented.