Abstract
During our research at the Central Research Institute of Electric Power Industry (CRIEPI), we have developed a high-efficiency oxy-fuel integrated coal gasification combined cycle (IGCC). In this system, CO2 in an exhaust gas from a heat recovery steam generator (HRSG) is used as both a gasifying agent and a carrier gas for coal and char. In the development of this system, CO2 enrichment gasification tests were carried out using a 3t/day scale coal gasification facility, a pressurized two-stage entrained-flow gasifier. In the tests, it was confirmed that the CO2 gasification (C+CO2→2CO) is promoted and that the effect improves gasification performance. In addition, steam generated by the HRSG is used as a gasifying agent at this system. The steam gasification (C+H2O→CO+H2) is promoted by injecting steam into a gasifier, but the output of a steam turbine is reduced. Therefore, it is necessary to consider the optimum conditions for the entire system. In this study, in order to examine the conditions for greatly improving the gasification performance by steam injection into a gasifier, the influences of the oxygen ratio on gasification promoted by steam injection was investigated using the gasifier.
