成果報告書詳細
管理番号20100000001380
タイトル*平成21年度中間年報 革新的ゼロエミッション石炭ガス化発電プロジェクト 革新的ガス化技術に関する基盤研究事業 石炭ガス化発電用高水素濃度対応低NOX技術開発(H20-H22)
公開日2010/9/9
報告書年度2009 - 2009
委託先名株式会社日立製作所
プロジェクト番号P08020
部署名クリーンコール開発推進部
和文要約和文要約等以下本編抜粋:1. 研究開発の内容及び成果等 二酸化炭素(CO2)排出量の削減に必要な技術とされるCO2回収・貯留付石炭ガス化発電プラントでは,燃焼前回収方式によりCO2を回収する場合,CO2回収率に応じて水素濃度が幅広く変化する高水素濃度燃料がガスタービンに供給される。 水素は発火しやすく燃焼速度が速いため,予混合燃焼方式の燃焼器で高水素濃度燃料を燃焼させた場合,燃焼室内にある火炎が予混合器流路内に逆火する可能性が高くなり,燃焼器の信頼性が低下する恐れがある。一方,拡散燃焼方式の燃焼器では高水素濃度燃料の安定燃焼は可能であるが,窒素酸化物(NOx)の排出濃度が増加するため,環境規制を満足するには窒素,あるいは水や蒸気を燃焼器に噴射して局所の火炎温度を低下させ,NOx排出濃度を低減する必要がある。そのため,拡散燃焼方式では発電効率の低下や噴射設備の初期コストおよびプラントランニングコストの上昇という課題が生じる。したがって,CO2回収・貯留付石炭ガス化発電プラントでは,燃料中の水素濃度の幅広い変化に対応でき,窒素,あるいは水や蒸気などの噴射が不要で,かつNOx排出濃度が低いドライ低NOx燃焼器が必要となる。
英文要約 Abstract: An integrated coal gasification combined cycle (IGCC) plant with carbon dioxide (CO2) capture and storage (CCS) will be required to reduce CO2 emissions. In this plant with pre-combustion carbon capture system, gaseous fuels containing high concentration of hydrogen (H2), ranging widely according to the carbon capture rate, are supplied to a gas turbine. The existing premixed combustors cannot achieve stable combustion of such high hydrogen content fuels because of the risk of flashback and/or auto-ignition due to the low ignition energy and fast burning velocity of hydrogen. The traditional diffusive combustors cannot meet low-emission requirement, and thus injection of a diluent into the combustion zone is required for suppressing the increased nitrogen-oxide (NOx) emissions, which results in lower plant efficiency and higher capital and operational costs. The objective of this research and development is to develop a dry low-NOx combustion technology for high hydrogen content fuels with H2 concentration ranging widely. This technology is based on a multiple co-axial jet burner, i.e., ‘cluster burner’, which can achieve stable low-NOx combustion of high hydrogen content fuels-with a wide range of hydrogen concentrations-without modifying its configuration. In the previous fiscal year, we found the burner’s configurations that achieve low-NOxemissions of less than 10 ppm for the fuels with a wide range of hydrogen concentrations under an atmospheric pressure. Moreover, a low-NOx combustor with multiple cluster burners was produced. In this fiscal year, the following three activities are done. (1)Test of a multi-cluster-burner-type low-NOx combustor under a middle pressure condition: The low-NOx combustor is tested under a middle pressure of 0.6 MPa. This combustor has a pilot burner in the center and six main burners around it. The results show that the NOx emissions at the rated load are 6 ppm for ‘CCS0%’ fuel (H2:40%) and 8 ppm for ‘CCS30%’ fuel (H2:55%). This finding shows that the combustor achieves dry low-NOx combustion of high hydrogen content fuels. (2)Study on burner’s configurations (test under an atmospheric pressure): Tests are carried out under an atmospheric pressure to investigate the effects of the burner’s perforated plate shape and the air hole size distribution on the combustion characteristics. The results show that the convex-plate burner is effective in reducing NOx emissions, and that the air hole size distribution is effective in extending the stable combustion ranges. (3)Simulation of turbulent combustion in cluster burners: The simulation is performed for the flat-plate and the convex-plate burners using a unified combustion model that is applicable to both premixed combustion and diffusion combustion seamlessly. The results show that the simulation captures the behaviors of lifted flame qualitatively, and that the high-temperature region becomes smaller for the convex-plate burner because of flow changes outside it.
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