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The Gas Research Institute (GRI) has begun an R&D Program directed towards natural gas processing issues. Of particular interest is research on problems connected with small-scale subquality natural gas processing. Both fundamental, knowledge-building and applied research are carried out. Studies of the resource base were undertaken in order to focus the program on those areas of greatest importance. The size of the total resource was estimated at 600 TCF (17 Tm3), of which approximately 40% had significant H, S, COy or K2 contamination. The size of the present and estimates of the future Lower-48 gas processing industry was then developed based on the resource estimates and other factors. An engineering and construction firm, M.W. Kellogg Company, was contracted with to provide a suite of designs/cost estimates for representative industry standard small-scale plants to serve as a baseline with which to evaluate new technology against These results are expected to be available early in 1991. Major findings of the - studies so far are an unexpectedly large regime of economic viability for hybrid systems of amines with membranes for CO2 removal. Two major field activities were started - testing of cellulose acetate membranes for CO2 removal with simultaneous dehydration, and testing of the Su£Ferox liquid redox process for sulfur recovery.

Coal gasification can generate hydrocarbon gases that may be utilized for the synthesis of chemicals or liquid fuels, or for fuel cell power generation, if extensive, deep syngas cleaning is first conducted. Conventional gas cleaning technology for this duty is expensive and may limit the feasibility of coal usage for such applications. The Siemens Westinghouse Power Corporation has proposed a novel scheme for polishing sulfur, halide, and particulate from gases to meet very stringent cleaning requirements for chemical synthesis, or for fuel cell power generation. This "Ultra-Clean" gas polishing process is a dry process, injecting fine sulfur and halide sorbent particles into two stages of barrier filter-reactors, or granular bed filter-reactors, to accomplished the gas polishing by dry sorbent adsorption of the contaminants. The sorbent materials for each stage, their feed rates, and the two stage temperatures must be specified to satisfy the gas cleaning requirements of any specific application, with the process having the potential for sulfur species less than 60 ppbv, halides less than 10 ppbv, and particulate less than 0.1 ppmw.The Base Program experimental activities described in this report have been completed to identify candidate sorbents and suitable operating conditions for each of the two stages of the Ultra-Clean process. The laboratory process simulation testing has identified a set of zinc-based and sodium-based, -325 mesh sorbents for each of the two stages that yield the performance potential for meeting the most stringent gas cleaning requirements. With these selected sorbents, the Stage I temperature is 499 C (930 F) and the Stage II temperature is 288 C (550 F).Conceptual commercial process evaluation of a novel gas cleaning process that utilizes the Ultra-Clean gas polishing process has been performed to devise potentially viable process details for two applications: a general chemical or liquid fuel synthesis application, and a solid oxide fuel cell power generation application. Commercial process performance and economics have been estimated for this novel gas cleaning process. The results indicate promising performance and economic potential compared to the conventional, Rectisol-based, gas cleaning technology. Sorbent maximum acceptable consumption criteria have been extracted from the commercial process evaluations and show that relatively high, once-through sorbent feed rates can be economically viable in the Ultra-Clean gas polishing process. The process can also incorporate ammonia removal and mercury removal. The next phase of the program will conduct integrated, bench-scale testing of the Ultra-Clean syngas polishing process on a sub-scale coal gasifier.iii

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