Development of Ceramic Gas Turbine Combustor for 300kW-Class(CGT301)

The combustor for 300kW class ceramic gas turbine (CGT301) has been developed to achieve high thermal efficiency of 42%. The combustor inlet air temperature and the turbine inlet temperature(TIT) are higher compared with the conventional same class gas turbine. The “pilot” CGT system, with a recuperator to recover the waste heat in the exhaust gas, can heat combustor inlet air up to 1013K(740°C) at TIT of 1623K(1350°C). Low NOx emission is one of the important problems for the CGT combustor. To solve the problem, the lean premixed combustion method was applied. Stable combustion is another important problem for the lean premixed combustor. To solve the problem, this combustor employed the variable geometory system and the fuel staging system. The former controlled the temperature in the combustion zone. The latter optimized the distribution of air/fuel concentration in the mixing zone. The CGT system has achieved both stable combustion and low NOx emission. NOx emission was reduced to 17.6 ppm against the “primary type” CGT target of 70 ppm under the full load condition at TIT of 1200°C in combustor rig test. The engine tests of “primary type” CGT with a ceramic combustor, which did not employ the variable geometry system and the fuel staging system, were conducted successfully for a total of 32 hours without any damage of the ceramic combustor under the full load condition.