Development of Dry Low-NOx Combustor for 300 kW Class Gas Turbine Applied to Co-Generation Systems

Abstract

A 300 kWe class gas turbine which has a two-shaft and simple-cycle has been developed to apply to co-generation systems. The gas turbine engine is operated in the range of about 30% partial load to 100% load. The gas turbine combustor requires a wide range of stable operations and low NOx characteristics. A double staged lean premixed combustor, which has a primary combustion duct made of Si3N4 ceramics, was developed to meet NOx regulations of less than 80 ppm (corrected at 0% oxygen). The gas turbine with the combustor has demonstrated superior low-emission performance of around 40 ppm (corrected at 0% oxygen) of NOx, and more than 99.5% of combustion efficiency between 30% and 100% of engine load. Endurance testing has demonstrated stable high combustion performance over 3,000 hours in spite of a wide compressor inlet air temperature (CIT) range of 5 to 35 degree C.. While increasing the gas generator turbine speed, the flow rate of primary fuel was controlled to hold a constant equivalence ratio of around 0.5 in the CIT range of more than 15 C. The output power was also decreased while increasing the CIT, in order to keep a constant temperature at the turbine inlet. The NOx decreases in the CIT range of more than 15 C. On the other hand, the NOx increases in the CIT range of less than 15 C when the output power was kept a constant maximum power. As a result, NOx emission has a peak value of about 40 ppm at 15 C.