Combined biomass and black liquor gasifier/gas turbine cogeneration at pulp and paper mills

Kraft pulp and paper mills generate large quantities of black liquor and by product biomass suitable for gasification. These fuels are used today for o nsite cogeneration of heat and power in boiler/steam turbine systems. Gasif ication technologies under development would enable these fuels to be used in gas turbines. This paper reports results of detailed full-load performan ce modeling of pulp-mill cogeneration systems based on gasifier/gas turbine technologies and, for comparison, on conventional steam-turbine cogenerati on technologies. Pressurized, oxygen-blown black liquor gasification, the m ost advanced of proposed commercial black liquor gasifier designs, is consi dered, together with three alternative biomass gasifier designs under comme rcial development (high-pressure air-blown, low-pressure air-blown, and lo- pressure indirectly-heated). Heavy-duty industrial gas turbines of the 70-M Wc and 25-MWc class are included in the analysis. Results indicate that gas ification-based cogeneration with biomass-derived fuels would transform a t ypical pulp mill into a significant power exporter and would also offer pos sibilities for net reductions in emissions of carbon dioxide relative to pr esent practice.