Continuously stirred tank reactor unsteady state operations

Fig. 1.9. Continuous stirred-tank reactor showing steady state operation (a) and two modes of unsteady state operation (b) and (c)...

Poehlein [81] identified major problems encountered with the development of continuous emulsion polymerization processes. It was shown that the development of commercial continuous emulsion polymerization processes involves the consideration of many factors associated with process design and product quality. These factors include the effects of inhibitor, polymerization rate, particle size distribution, copolymer composition, addition strategy of feed streams, unsteady-state operation, and reactor design on continuous emulsion polymerization processes. The author then used a two-continuous stirred tank reactor series to elucidate key continuous emulsion polymerization mechanisms and generate the knowledge necessary for the development of commercial continuous processes. 

After specifying the energy form, the catalyst and the phases in contact, the next task is to decide whether to conduct the reaction in a batch or continuous mode. In the batch mode, the reactants are charged to a stirred-tank reactor (STR) and allowed to react for a specified time. After completing the reaction, the reactor is emptied to obtain the products. This operating mode is unsteady state. Other unsteady-state reactors are (1) continuous addition of one or more of the reactants with no product withdrawal, and (2) all the reactants added at the beginning with continuous withdrawal of product. At steady-state, reactants flow into and products flow out continuously without a change in concentration and temperature in the reactor. 

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