DEVELOPMENT OF OXY-FUEL IGCC SYSTEM WITH CO_2 RECIRCULATION FOR CO_2 CAPTURE - EXPERIMENTAL EXAMINATION ON EFFECT OF GASIFICATION REACTION PROMOTION BY CO_2 ENRICHED USING BENCH SCALE GASIFIER FACILITY -

摘要

To cope with global wanning problem, utility companies are required to reduce CO_2 emission from pulverized coal fired power plants. Japanese utility companies are advancing various measures to improve plant thermal efficiency and to promote utilization of biomass as a fuel. In Europe and America, CO_2 capture and storage (CCS) technology is regarded as one effective approach, and various demonstration projects are planned all over the world. However, the introduction of conventional CO_2 capture system to power station causes a decrease in the plant thermal efficiency and an increase in the power generating cost. In this reason, it is necessary to develop a new power generating system with high thermal efficiency. Therefore, Central Research Institute of Electric Power Industry (CRIEPI) proposed an innovative integrated coal gasification combined cycle power generating system (IGCC) with CO_2 capture whose plant thermal efficiency is very high, and is working on the research and development of the new system. This is a system to combine a new oxygen-CO_2 blown coal gasifier in that captured CO_2 is used with the closed gas turbine in which coal gas from the gasifier is burned with the gas mixed oxygen and recycled exhaust CO_2. The system has the following features. The gasification performances improve greatly. The processes of concentrating and separating CO_2 are unnecessary. It is estimated that the carbon conversion efficiency (CCE) and the cold gas efficiency (CGE) in oxygen-CCh blown gasifier improve more than conventional oxygen blown gasifiers by the effect of the gasification reaction promotion of CO_2 by gasifying coal with oxygen and CO_2. As a result, the gasifier and the char recycling system can make to compact, and the equipment cost can be reduced. This paper reports on examination of CO_2 promotion effect on the gasification performances by gasification test using a bench scale gasifier facility.