97/03748 Co-gasification of coal and other domestic fuels

Abstract

Almost all new additions to electrical generation in the USA are natural gas combined cycle systems (NGCC) systems. This trend reflects the development of high efficiency gas turbines (GT), low capital, operation and maintenance of NGCC systems and optimism as to natural gas resources. With utility deregulation these developments will seriously restrict long term use of coal and other solid fuels unless a los cost integrated gasifier (IG) fed by low cost feedstocks can be coupled with a CC system. This study mainly considers on-site cogasification of coal with other domestic fuels in an indirectly heated gasifier as a long term strategy for lowering the effective costs of IGGT systems. The authors also consider cocombustion of coal with other low cost domestic fuels as a near term strategy for minimizing fuel costs for competitiveness under utility deregulation. These fuel blending approaches both make use of common fast copyrolysis processes. They examine fast copyrolysis from a molecular point of view searching for advantageous feedstock blends. The authors conclude that blending coal with complementary coals, biomass, MSW or natural gas would be useful in near term cocombustion systems and long term integrated cogasification combined cycle or cogeneration systems.