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Synthesis of integrated chemical systems

Wen-Chi Chang, University of Massachusetts Amherst


Algorithmic and heuristic-based approaches are proposed for synthesizing integrated chemical systems. The former is used in the synthesis of reactor network and reactor-recycle-separator systems; the latter in the synthesis of integrated crystallization systems. In the algorithmic method, a network, or superstructure, which embeds all possible equipment to be used in the process and the potential interconnections among the equipment is generated. The procedure for generating the reactor network and the reactor-recycle-separator flow sheet structure is described. A nonlinear programming (NLP) problem is then formulated for the network. The optimal flow sheet and accompanying operational conditions are obtained by solving the NLP problem. For integrated crystallization process synthesis, a heuristic-based systematic procedure is developed. In a step-by-step manner, the procedure guides the user to generate alternative flow sheets for a given crystallization task. First, the required unit operations are determined by comparing the product specifications (production rate, product purity, and others) with the crystallizer effluent characteristics (occlusions, inclusions, crystal size, and others). Second, the destinations of the reaction solvent, mother liquor, wash liquid, recrystallization solvent, and drowning-out solvent are assigned. Then, the solvent recovery system is considered to recover the solvents and unconverted reactants, and to remove impurities from the system. Downstream system problems such as excessive filtration time and/or filter size are often caused by unfavorable crystal size. Various crystallizer designs to improve the crystal size distribution are discussed; short-cut equipment models are used to evaluate the alternatives for potential improvement. Issues related to minimization of inclusion impurities and heat integration are also examined. Guidelines are provided to help the user to add more details to the flow sheet at each level.

Subject Area

Chemical engineering|Systems design

Recommended Citation

Chang, Wen-Chi, "Synthesis of integrated chemical systems" (1998). Doctoral Dissertations Available from Proquest. AAI9841850.