Process Synthesis, Modeling and Optimization of Continuous Cooling Crystallization with Heat Integration: Application to the Chilled Ammonia CO2 Capture Process

A systematic method is presented to design multistage continuous crystallization processes with heat integration. A general method has been applied to a specific case, namely the integrated absorption-based process for postcombustion CO2 capture in which solid formation is exploited. At first, a set of viable process flow schemes based on different equipment configurations for crystallization has been selected. Then, a rate-based model capable of describing the phenomena occurring during crystallization and dissolution of particles coupled with heat transfer has been developed for design and optimization purposes. Because of the broad design space and the interplay between unit operations, the mathematical model stands out as the key tool for the assessment of the process feasibility. Furthermore, a multiobjective optimization of the solid handling section has been performed, the aim of which is twofold: identifying optimal operating conditions and gathering information on the effect of and the synergy among the different design variables on the process performance. The results are evaluated on the basis of key performance indicators such as productivity and specific energy penalty, as well as of the particle size distribution of the crystals obtained during crystallization.