A prototype machine for a next generation microturbine system applying a simple humid air turbine system (design target of electrical output: 150 kW, electrical efficiency: 35% LHV) was developed for its laboratory evaluation. A low NOx combustor which applied a lean-lean zone combustion concept and water lubricated bearings were developed for the prototype machine. Operation using two water lines for the humid air turbine (HAT) was proposed as an effective way to obtain rated electric output to ambient temperature of 40 deg C. Tests for the main components were done successfully. Motoring tests, full speed test with no load, 50% load and 70% load tests as preliminary tests for rated load tests were also carried out successfully. Low NOx emission of 7.6 ppm and high efficiency of 95.6% for the power conversion system were achieved in the partial load tests. At the first rated load test without HAT and Water atomizing inlet air cooling (WAC) that followed those partial load tests, 150.3 kW electric output with electrical efficiency of 32% was obtained.
The successful development of oxygen-blown integrated coal gasification combined cycle (IGCC) technology requires gas turbines capable of achieving the dry low nitrogen oxides (NOx) combustion of hydrogen-rich syngas for low emissions and high plant efficiency. The authors have been developing a "multiple-injection burner" to achieve the dry low-NOx combustion of hydrogen-rich syngas. This burner consists of multiple fuel nozzles and a perforated plate with multiple air holes. At each injection point, one fuel nozzle and one air hole are installed coaxially, so that a fuel jet surrounded by a sheath air jet is injected. The burner achieves low-NOx combustion by mixing fuel and air rapidly with multiple fuel-air coaxial jets, and prevents flashback into the burner by lifting the flame from itself. The purpose of this paper is to present the test results of multi-can combustors equipped with multiple-injection burners in an IGCC pilot plant, and evaluate combustor performance by focusing on the effects of flame shapes. The syngas fuel produced in the plant contained approximately 50% carbon monoxide, 20% hydrogen, and 20% nitrogen by volume. In the tests, the combustor with slenderer flames achieved lower NOx emissions of 10.9 ppm (at 15% oxygen) diluent-free with high stability and high reliability, and reduced both combustor liner and burner plate metal temperatures at the maximum gas turbine load. These findings demonstrated that the multiple-injection combustor achieved the dry low-NOx combustion of the syngas fuel in the plant. : Integrated coal gasification combined cycle (IGCC), Gas turbine, Dry low NOx combustor, Multiple injection burner, Hydrogen-rich syngas fuel
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