報告書番号

W01005

タイトル（和文）

酸素吹きガス化中カロリー燃料用ガスタービン燃焼器の開発 -－第１報 フュエルＮＯxとサーマルＮＯx同時低減燃焼技術－ -

タイトル（英文）

Development of Combustor for Medium-Btu Fueled Gas Turbine in Oxygen-blown IGCC -1st report, Combustion Technology for Reducing both Fuel-NOx and Thermal-NOx Emissions-

概要 （図表や脚注は「報告書全文」に掲載しております）

国内外では、石炭利用高効率発電システムとして各種ガス化複合発電システム(IGCC)の開発･実証が進められている。当所では､1987年から空気吹きガス化+乾式ガス精製、酸素吹きガス化+湿式ガス精製を対象に1300℃および1500℃級IGCC用ガスタービン低NOx燃焼器の開発を進めてきた。酸素吹きIGCCのより一層の高効率化を図るためには乾式ガス精製の採用が不可欠であり、その際、酸素吹きガス化中カロリー燃料の高い火炎温度に起因してサーマルNOxが増加すると共に、乾式ガス精製方式により除去されずにガス化燃料中に残留するNH3に起因するフュエルNOxが多量に発生する。酸素吹きガス化+乾式ガス精製の実用化のためにはサーマル/フュエルNOx同時低減燃焼技術の開発が重要である。本報告では、当所で提案・開発したサーマルNOx低減のための窒素噴射とフュエルNOx低減のための還元二段燃焼法を、酸素吹きガス化+乾式ガス精製による中カロリー燃料に適用し、サーマル/フュエルNOx排出特性を確認すると共に、1500℃級燃焼器の設計方針を明らかにした。

概要 （英文）

In order to improve the thermal efficiency of the oxygen-blown IGCC (Integrated Gasification Conbined Cycle) for stricter environmental standards and cost-effective option, it is necessary to adopt the hot/dry gas cleaning system. In this system, the flame temperature of medium-btu gasified fuel is higher and so NOx production from nitrogen fixation is expected to increase significantly. Also the gasified fuel contains fuel nitrogen, such as ammonia, in the case of employing the hot/dry gas cleaning system. This ammonia is easily oxidised into fuel-NOx in the combustor. For higher thermal efficient operations of all kinds of IGCC, low NOx combustion technology for reducing both the fuel-NOx and thermal-NOx emission has to be developed. In this paper, we clarified the characteristics in the case of applying the two-stage combustion and nitrojen-injection method, and the useful engineering guidelines for the low-NOx combustor design of oxygen-blown gasified, medium-btu fuels. Main results obtained are as follows:(1) Based on the basic combustion tests using the small diffusion burner, we clarified that primary equivalence ratio has to be adjusted for compositions, such as methane concentration, and fuel calorific values of medium-btu gasified fuel for higher efficient using of the two-stage combustion method for reducing both thermal-NOx and fuel-NOx emission.(2) It is necessary to elongate the residence time of the combustion gas in the primary combustion zone to reduce the fuel-NOx emission in the case of two-stage combustion.(3) From the preliminary combustion tests of the medium-btu fueled combustor, two-stage combustion with nitrogen direct injection results in reductions both in NOx production from nitrogen fixation, 10ppm or less(corrected at 16% O2), and in the conversion rate of NH3 to NOx, 80% (CH4=3%, NH3=500ppm) in the gas turbine operational conditions for IGCC. Consequently, CO emission concentration decreased to a significant level, as low as 10ppm, or combustion efficiency was almost always 100% and total NOx emissions to 45ppm(corrected at 16% O2). From the above results, it is clarified that two-stage combustion method with nitrogen direct injection is great effective for reducing both the thermal-NOx and fuel-NOx emissions in IGCC. Based on the obtained design concepts, we will construct the new combustor, test it using the simulated gas, and estimate the combustion characteristics in gas turbine operational conditions with actual gasified fuel.

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