POWER-GEN Europe and REWE 2017

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Validation of Ignition Reliability in SGT-750 Combustion Chamber for Diluted Natural Gas at Extremely Low Ambient Temperature (Room Rheinsaal 4)

In order to address a wider range of gaseous fuels a combustion and operational test was performed in the SGT-750 prototype unit on natural gas diluted with inert gases. At up 30 vol% N2 and 20 vol% CO2 content in natural gas the flame ignition and acceleration of the unit were demonstrated with satisfactory reliability. The engine test was followed by complementary combustion tests of the SGT-750 original single burner combustor, carried out in a high pressure as well as in an atmospheric combustion test rig at conditions corresponding to extremely cold ambient. In the former case the combustion of the CO2/N2 diluted natural gas was studied for the heat rates, air pressures and temperatures scaled to the engine operation at -60˚C ambient across the SGT-750 operating line from idle to 100% load. It was shown that the combustor could be operated with preserved reliability and performance. The same test hardware was used in the latter case when the process air was cooled down to -60 ˚C. Air flow rate to the rig was the same as at start-up conditions in the engine. A special air supply unit incorporating liquid air storage, steam driven liquid air evaporator and the flow and temperature control station was assembled for this test. The test was performed for a variety of air flow rates in temperature range -30 ÷ -60 ˚C, start settings of fuel flow rates to the igniter and main burner to find the optimal ignition conditions. For the test purposes even the energy and the frequency of the spark exciter was altered. The test was done for natural gas and its blends with inert gases. The fuel could be ignited at the power corresponding to SGT-750 start up conditions for the air temperature of -60 ˚C with the igniter and the burner fed with pure natural gas and blends with up to 55 vol% N2 and 30 vol% CO2. The engine and rig tests have shown that SGT-750 can be started and operated within a broad range of ambient conditions (arctic climate) and low heating value fuel blends.