The successful development of coal-based integrated gasification combined cycle (IGCC) technology requires gas turbines capable of achieving the dry low nitrogen oxides (NOx) combustion of hydrogen-rich syngas fuels for low emissions and high plant efficiency. Mitsubishi Hitachi Power Systems, Ltd. (MHPS) has been developing a “multiple-injection burner” to achieve the dry low-NOx (DLN) combustion of hydrogen-rich syngas fuels. The purposes of this paper are to present the test results of a multican combustor 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), reduced combustor liner and burner plate metal temperatures, and lowered combustion efficiency at the maximum gas turbine load. The test results showed that the slenderer flames were more effective in reducing NOx emissions and liner/burner plate metal temperatures. A comparison with the diffusion-flame combustor demonstrated that the multiple-injection combustors achieved the dry low-NOx combustion of the syngas fuel in the plant.

The successful development of the coal-based integrated gasification combined cycle (IGCC) with carbon capture and storage (CCS) requires gas turbines capable of achieving dry low nitrogen oxide (NOx) combustion of hydrogen-rich syngas fuels for low emissions and high plant efficiency. This chapter describes the development of a "multi-cluster combustor" as a state-of-the-art dry low NOx combustor for hydrogen-rich syngas fuels.The combustor consists of multiple clusters of pairs of one fuel nozzle and one air hole that are installed coaxially. The essence of the design concept is the integration of two key technologies: rapid mixing of fuel and air for low NOx and flame lifting for flashbackresistant combustion. The combustor has been developed in three steps: burner development, combustor development, and feasibility demonstration for practical plants. The combustor was tested with a practical syngas fuel in a multi-can combustor configuration in an IGCC pilot plant in the final step. The combustor achieved the dry low NOx combustion of the syngas fuel in the pilot plant and the test results demonstrated the feasibility for achieving dry low NOx combustion of the syngas fuel in practical plants.

An oxygen-blown integrated coal gasification combined cycle (IGCC) plant with pre-combustion carbon dioxide capture and storage (CCS) is one of the most promising means of zero-emission generation of power from coal. In an IGCC plant with CCS, hydrogen-rich syngas with a wide variation of hydrogen contents is supplied to a gas turbine. Such hydrogen-rich syngas poses a great challenge to a low NOx combustor based on premixed combustion technology, because its high flame speed, low ignition energy, and broad flammability limits can cause flashback and / or auto-ignition. On the other hand, a diffusion combustor suffers from the high flame temperature of syngas and the resulting high NOx emission. The authors applied a “multi-injection burner” (cluster burner) concept to a preliminary burner for hydrogen-rich syngas simulating that from IGCC with CCS. In a preliminary experiment under atmospheric pressure, the multi-injection burner worked without any flashback or any blowout. A prototype multi-cluster combustor based on the results of that preliminary study was made to be a dry low NOx combustor for hydrogen-rich syngas of IGCC with CCS. It was tested in experiments, which were carried out under medium pressure (0.6MPa) using test fuels simulating syngas from IGCC with a 0% carbon capture rate, a 30% carbon capture rate and a 50% carbon capture rate. The test fuels contained hydrogen, methane and nitrogen, and had hydrogen content ranging from 40% to 65%. The following conclusions were drawn from the test results: (1) The tested combustor allows stable combustion of fuels simulating 0%, 30%, and 50% CCS. (2) A convex perforated plate swirler is effective to suppress combustion oscillation, which allows NOx emissions to be less than 10ppm through the variation of fuel simulating 0%, 30% and 50% CCS.

The successful combination of coal-based integrated gasification combined cycle (IGCC) technology with carbon dioxide (CO2) capture and storage (CCS) requires gas turbines that can achieve dry low-NOx combustion of hydrogen-rich syngas with a wide range of hydrogen concentrations for lower emissions and higher plant efficiency. The authors have been developing a “multiple-injection burner” to achieve dry low-NOx combustion of such hydrogen-rich fuels. The purpose of this paper is to experimentally investigate the combustion characteristics of a multiple-injection burner with a convex perforated plate in order to determine its effectiveness in suppressing combustion oscillation. The experiments were conducted at atmospheric pressure. Three kinds of fuel with hydrogen concentrations ranging from 40 to 84% were tested. The temperature of the combustion gas at the burner exit was 1775 K. The experimental results show that the convex burner was effective in suppressing combustion oscillation: it achieved stable low-NOx emissions of less than 10 ppm for all the test fuels. These findings demonstrate that the convex burner can achieve stable low-NOx combustion of hydrogen-rich fuels with a wide range of hydrogen concentrations by suppressing combustion oscillation.

An oxygen-blown integrated coal gasification combined cycle (IGCC) plant with precombustion carbon dioxide capture and storage (CCS) is one of the most promising means of zero-emission generation of power from coal. In an IGCC plant with CCS, hydrogen-rich syngas with a wide variation of hydrogen contents is supplied to a gas turbine. Such hydrogen-rich syngas poses a great challenge to a low NOx combustor based on premixed combustion technology, because its high flame speed, low ignition energy, and broad flammability limits can cause flashback and/or autoignition. On the contrary, a diffusion combustor suffers from the high flame temperature of syngas and the resulting high NOx emission. The authors applied a “multi-injection burner” concept to a preliminary burner for hydrogen-rich syngas simulating that from IGCC with CCS. In a preliminary experiment under atmospheric pressure, the multi-injection burner worked without any flashback or any blowout. A prototype multicluster combustor based on the results of that preliminary study was made to be a dry low NOx combustor for hydrogen-rich syngas of IGCC with CCS. It was tested in experiments, which were carried out under medium pressure (0.6 MPa) using test fuels simulating syngas from IGCC with a 0% carbon capture rate, a 30% carbon capture rate, and a 50% carbon capture rate. The test fuels contained hydrogen, methane, and nitrogen, and had a hydrogen content ranging from 40% to 65%.The following conclusions were drawn from the test results: (1) the tested combustor allows the stable combustion of fuels simulating 0%, 30%, and 50% CCS, (2) a convex perforated plate swirler is effective to suppress combustion oscillation, which allows NOx emissions to be less than 10 ppm through the variation of fuel simulating 0%, 30%, and 50% CCS, (3) the extended stable combustion region and enhanced entrainment and mixing due to the convex perforated plate improves the cooling of the combustor liner metal to be less than the liner metal temperature criterion.