Effect of Pressure on Emission Characteristics in LBG-Fueled 1500°C-Class Gas Turbine

Abstract

Developing integrated coal gasification combined cycle (IGCC) systems ensures cost-effective and environmentally sound options for supplying future power generation needs. In order to enhance thermal efficiency of IGCC and to reduce NOx emission, a 1500°C-class gas turbine combustor for IGCC was designed, tested, and the performance of the combustor was evaluated under pressurized conditions. The designed combustor had the following three characteristics: (1) in order to assure the stable combustion burning low-Btu gas (LBG), an auxiliary combustion chamber was installed at the entrance of the combustor; (2) to reduce fuel NOx emission that was produced from the ammonia (NH3) in the fuel, the rich-lean combustion method was introduced; and (3) to compensate for the declined cooling-air associated with the higher temperature of the gas turbine, the tested combustor was equipped with a dual-structure transition piece so that the cooling air in the transition piece can be recycled to cool down the combustor liner wall. As a result of combustor tests, it is confirmed that CO emission is less than 20 ppm, the conversion rate of NH3 which contains about 1000 ppm in the coal gasified fuel to NOx shows 40 percent or below, and the liner wall temperature remained below almost 850°C under high pressure (1.4 MPa), rated load condition.