Abstract: In power plants having no gas source，a feasible option is that re-burning of coal gas produced in powder coal burner to reduce emission of NO_x，i.e.in order to the coal gas，using air and water vapor as medium to gasify a part of coal below 1000℃.In this paper GRI3.0 mechanism is selected and after simplifying a multi-step mechanism including 26 species and 63 reactions is got for simulating a 130 t powder coal burner.The design calculation of the inlet and the ratio of re-burning gas are done and a alteration design that can make 80% reduction of NO_x is proposed.The results show that the re-burning does not have significant influence on burnout ratio of coal.The inlet of the third air wind should be moved up 3 m to increase the reduction time of NO_x.The ratio of re-burning gas should be controlled at 30% to strengthen its reduction performance.

Key words: coal gas, NO_x reduction, kinetic analysis, coupling calculation

摘要： 在没有气源的电厂，可以采用煤制气再燃低NO_x燃烧技术，即采用空气和水蒸气作为气化介质，在1000℃以下进行气化得到煤制气，实现部分煤气化再燃低NO_x燃烧技术。本文选用GRI3.0反应机理，简化后得到了适用于NO_x还原计算的简化机理，包括26个组分和63个反应，对130 t煤粉炉进行了多步反应机理和CFD耦合计算的尝试，并对还原气喷口和还原气比例进行了设计计算，提出了改造设计方案，可实现NO_x还原率超过80%。计算结果表明，采用部分煤制成再燃气燃烧没有明显影响煤的燃尽率；130 t煤粉炉设计的三次风喷口应该上移3 m，以增加再燃反应时间；再燃气比例可设计为30%，以增加NOx还原效果。

关键词: 煤制气, NO_x还原, 反应动力学, 耦合计算