Development of the Advanced Humid Air Turbine

Abstract

Humid air turbine systems that are regenerative cycle using humidified air can achieve higher thermal efficiency than gas turbine combined cycle (GTCC) power plant even though they do not require steam turbine, high combustion temperature, or high pressure ratio. In particular, the advanced humid air turbine (AHAT) system appears to be highly suitable for practical use because its composition is simpler than that of other systems. Moreover, the difference in thermal efficiency between AHAT and GTCC is greater for small and medium-size gas turbines. To verify the system concept and the cycle performance of the AHAT system, a 3 MW-class pilot plant was constructed. As a result of an operation test, the planned power output of 3.6 MW was achieved, so that it was confirmed the feasibility of the AHAT as a power-generating system. Moreover, the 40 MW-class AHAT test facility was developed and confirmed practicability of the AHAT system with a heavy-duty gas turbine for industrial use. In these AHAT systems, a cluster nozzle burner configuration, which has many coaxial jet streams of fuel and air, was adapted to cope with both flame stability and NOx reduction problems. From the test results, NOx emission is expected to be less than 10ppm for the future commercial AHAT system.