Syngas to Synfuels Process Development Unit Final Scientific/Technical Report

The process described is for the gasification of 20 kg/h of biomass (switchgrass) to produce a syngas suitable for upgrading to Fischer-Tropsch (FT) liquid fuels (gas, diesel, waxes, etc.). The gas stream generated from gasification is primarily composed of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), steam (H2O), and methane (CH4), but also includes tars, particulate matter, ammonia (NH3), hydrogen cyanide (HCN), hydrogen chloride (HCl), hydrogen sulfide ( H2S), carbonyl sulfide (COS), etc. as contaminants. The gas stream passes through an array of cleaning devices to remove the contaminants to levels suitable for FT synthesis of fuels/chemicals. These devices consist primarily of an oil scrubber (to remove tars and remaining particulates), sulfur scrubber (to remove sulfur compounds), and a wet scrubber (to remove NH3, HCl and remaining water soluble contaminants). The ammonia and oil scrubbers are absorption columns with a combination of random and structured packing materials, using water and oil as the adsorption liquids respectively. The ammonia scrubber performed very well, while operating the oil scrubber proved to be more difficult due to the nature of tar compounds. The sulfur scrubber is a packed bed absorption device with solid extrudates of adsorbent material, primarily composed of ZnO andmore » CuO. It performed well, but over a limited amount of time due to fouling created by excess tar/particulate matter and oil aerosols. Overall gas contaminants were reduced to below 1 ppm NH3, and less than 1 ppm collective sulfur compounds.« less