Slurry Fed Biomass Gasifier: Feedstock Preparation Techniques and Performance Results

摘要

Heightened interest in energy from biomass has resulted in a focused effort on biomassgasification for the production of syngas, hydrogen, and liquid fuels. Economic considerationsshow that pressurized gasification systems would be desirable in order to reduce plant capitalcosts for specific biomass feedstock thruputs. In addition there has been considerable effort indeveloping densification techniques for biomass feedstocks to reduce transportation and handlingcosts. Most effort to date has investigated dry feed thru a system of pressurized lockhoppersand/or char-bio-oil slurries which are applicable to certain types of conversion systems. In thispaper the possibility of using biosolids/water slurries for pressurized feed to the gasificationreactor is investigated. Both torrefied biosolids slurries and a hydrothermally treated biosolidslurry are investigated. Data and rheological modeling results are presented on biosolids andbiosolids/coal/water slurries. To better understand the performance the gas evolution and massdecay behavior of beachgrass and compost were examined with steam and CO_2 gasificationusing Thermogravimetric Analysis and Gas Chromatography. Analysis of gasification/pyrolysisbehavior of torrefied biomass has been investigated to expand the application of CO_2 into slurrybasedgasification. Results have shown that char reduction from a co-fed CO_2 and steam issignificant with a reduction from 15% remaining biomass to 5%. Torrefied biomass shows morereduction of char from 25% to 4%. Using CO_2 as the gasification medium for the thermalprocessing of biomass fuels, shows a more complete conversion to synthesis gas and a moreenergy efficient thermal treatment process. Also the possibility of biosolids and/or biosolids/coal/liquid CO_2 slurries is analyzed and benefits and applications discussed.