Hazardous material transfer systems: Justrite Mfg. Co. Des Plaines, Ill.

Abstract

The net greenhouse gases (GHG) emissions of conversional Fischer Tropsch (FT) synthetic fuels derived from coal are about double of those from petroleum fuels. Adding moderate amounts of biomass to coal can substantially reduce the carbon footprint of the indirect fuel production plant. The indirect coal–biomass to liquids (CBTL) technology with CO2 capture and storage (CCS) is more environmental friendly than the conventional coal to liquids (CTL) processes. This paper focuses on the selection of CCS technologies and obtaining their optimal operating conditions for a CBTL plant. A detailed process model is developed in Aspen Plus V7.3.2 for this purpose. In this plant, syngas is produced in the biomass/coal-fed co-gasifier. Then, a sour water gas shift (WGS) reactor converts a portion of the CO in the syngas to CO2 to obtain the desired H2/CO ratio in the syngas feed to the FT unit. Substantial amount of CO2 is captured before the FT reactor by using a dual-stage, selective physical solvent-based process. In the FT unit, the Fe-based catalyst is used in the low temperature FT (LTFT) slurry reactor to convert syngas to hydrocarbons. For selection of the post-FT CO2 capture technology, three candidate technologies – Selexol, MEA and MDEA/PZ, are evaluated. The results show that the MDEA/PZ technology with intercooling has the lowest overall penalty. Impacts of two key design variables, H2/CO ratio at the inlet of the FT unit and biomass/coal ratio of the feedstock, on the product yield and utility consumptions are investigated.