Takeo Saito

Full Scale Testing of a Cluster Nozzle Burner for the Advanced Humid Air Turbine

The advanced humid air turbine (AHAT) system, which has a humidifier and a heat recovery system has the advantage of improving the thermal efficiency of gas turbine power generation without needing an extremely high firing temperature and pressure ratio. A pilot plant and a prototype gas turbine adapted to the AHAT system have been developed. Before the pilot plant test, an experimental study using a combustion test rig was carried out to obtain the characteristics of a prototype combustor and it is described in this presentation. The combustion conditions in the AHAT system are characterized by both high humidity and high temperature air (17.6wt%, 629C). It is expected that a low flame temperature caused by the high humidity condition will decrease NOx emission while the high temperature air condition will sustain flame stability. However, the latter condition has the disadvantage of causing NOx emission and autoignition of fuel. A cluster nozzle burner configuration, which has many fuel and air coaxial jet streams, was previously proposed. The cluster nozzle burner can mix fuel and air effectively within a short time which makes it suited to the AHAT system and able to cope with both flame stability and NOx reduction problems. The combustion rig test results showed good combustion performance for the developed cluster nozzle burner. Both the high temperature condition of the AHAT system and the recirculation zone generated by swirling of center burner air sustained flame stability at a level sufficient for the nozzle burner in AHAT operation. The low flame temperature due to the high humidity condition was effective in decreasing NOx emission, which was less than 10ppm at 50-100% load.Copyright