Development of Multi Cluster Burner for Fuel Grade DME

Recently, DME (dimethyl ether: CH₃OCH₃) has attracted attention as a clean next-generation fuel, but it has the possibility of spontaneous ignition in gas turbine use. To avoid spontaneous ignition or flash-back, a coaxial jet cluster nozzle burner configuration was proposed previously, which can mix air and fuel effectively within a short distance. In this research, the full size multi cluster burner composed of coaxial jet cluster nozzle burners was designed, and combustion tests for gaseous fuel grade DME were carried out. (Fuel grade DME includes minor amounts of methanol and water as impurities.) In making the configuration tests of the multi cluster burner, the robust design method was applied. Characteristics of NOx emission, combustion efficiency, combustion stability, etc. were evaluated, and the optimal configuration of the combustor was determined. Also, the influences of impurities of fuel grade DME on the combustion performance were evaluated. With the optimal combustor, the prospects were good for achieving the targets, NOx < 20 ppm (16% O₂), combustion efficiency > 99.9%, and pressure oscillation < 3.5 kPa. Regarding the influences of impurities of fuel grade DME, there was no great difference in combustion efficiency and pressure oscillation with addition of impurities in this test range.