DESIGN OF OPTIMAL WASTE-GAS MINIMIZATION NETWORKS FOR A SYNTHETIC LIQUID FUELS (H-COAL) PLANT

To make alternative fuel sources economically competitive with crude o il fractionation processes, the volume of waste generated during produ ction of the synthetic fuel must be reduced in a cost-effective manner . The purpose of this paper is to develop a systematic methodology to design optimal waste minimization networks to tackle air emissions gen erated during the production of synthetic fuels. In particular, the mi nimization of acid gas emissions is accomplished with the aid of a rec ently developed design notion of synthesizing REActive Mass-Exchange N etworks, REAMEN. The selection of the optimum process for minimizing w astes from synthetic fuel plants is accomplished using a systematic te chnique for the simultaneous screening of all potentially applicable p rocesses. The design task is formulated as an optimization problem wit h trade-offs between economic and environmental objectives. A case stu dy is presented to demonstrate the power of the above design methodolo gy for the acid gas emissions from a typical H-coal liquefaction plant . Results indicate that the optimal desulfurization network that is re quired to yield environmentally acceptable standards at minimum cost c onsists of a single mass-exchange technology, absorption, and employs two different kinds of absorbing agents: a physical solvent, water, an d a chemical solvent, hot potassium carbonate.