Environmentally Conscious Manufacturing: Waste Reduction through Mass Exchanger Network Synthesis

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9528653 Manousioutakis UCLA The design of environmentally conscious manufacturing processes is a challenging problem. At risk are public health, the competitiveness of US industry, and the well being of the key chemical and manufacturing sectors of the economy. Direct costs dedicated to pollution control are in hundreds of billions of dollars, and as public demands for reduced or zero discharge grow, these costs escalate. These demands have made conventional, end-of-pipe treatment technoogies inadequate and expensive. To remain competitive in world markets, American industry must develop new manufacturing processes designed to avoid the generation of pollutants, rather than rely on technologies that capture pollutants once they have been generated. A current approach to this problem is in the design of separation systems, since recovery of raw materials and by-products from reactor effluents can lead to reduced raw material consumption and waste disposal costs. Thus a multi-technology based separation synthesis method that can systematically design flowsheets, featuring the optimum combination of the many separation options, could be instrumental in arriving at competitive, minimum waste generating processes. In an effort to develop waste reduction methods based on separation processes, and in particular distillation, the PI has been working on a concept that he calls mass-exchange network (MEN) synthesis and the "State-Space Approach". MEN synthesis systematically generates a cost-effective network of mass exchanges that preferentially transfers certain species from a set of rich streams to a set of lean streams. A mass exchanger is any countercurrent direct-contact mass-transfer operation (for example, absorption, desorption, adsorption, liquid-liquid extraction, ion exchange, vapor-liquid equilibrium). Mass exchangers, together with heat exchangers or other technologies (such as membrane separations), form the building blocks of separation networks. The "State-Space Appr oach" provides a flexible tool to synthesize mass/heat exchange networks, distillation column sequences and other hybrid networks using such tools as the "pinch" concept for mass and heat exchange. The end result is improved resource utilization through integration.