Design and simulation of a recirculating bed reactor for coal hydrogasification. Linear programming analysis of hydrogasification strategies

Abstract

This report describes an initial attempt to examine the implications of the process design on the recirculating bed hydrogasifier (RBR) operating conditions and the efficiency of RBR hydrogasification. The design and simulation of a recirculating bed reactor for coal hydrogasification requires that standards of performance be established for the hydrogasifier's operation. Primarily this means specifying optimal operating conditions - temperature, pressure and carbon conversion; however, it also means identifying the best mechanisms for control of the reactor heat balance - i.e., heat recovery and/or heat addition. Alternate routes to methane production include both direct hydrogenation of coal and methanation of carbon monoxide with hydrogen. In turn, the hydrogen used in each of these reactions can be produced in a variety of ways. Further, heat must be added to these processes by the combustion of carbon. It is obvious that these reactions can be assembled in a multiplicity of ways and still produce methane; however, the key to effective process design is to select an optimal arrangement of these reactions such that a maximum thermal efficiency is achieved. Maximizing the process thermal efficiency implies that a maximum carbon conversion to methane is achieved. Thus, by coupling the process design and themore » hydrogasifier design to the goal of maximizing thermal efficiency, a mechanism for designing the optimal hydrogasifier emerges.« less