墙式布置锅炉不同燃尽风率下燃用低挥发分煤的燃烧及NO_(x)生成特性  

Combustion and NO_(x)Formation Characteristics of Wall-fired Boiler fed with Low Volatile Coal at Different OFA Rates

作　　者：李松 井新经 贺萌 陈智超[4] LI Song;JING Xin-jing;HE Meng;CHEN Zhi-chao(Beijing Power Machinery Institute,Beijing,China,Post Code:100074;Xi′an Thermal Power Research Institute Co.,Ltd.,Xi′an,China,Post Code:710054;The Sixth Representative Office in Beijing of Rocket Force,Beijing,China,Post Code:100074;School of Energy Science and Engineering,Harbin Institute of Technology,Harbin,China,Post Code:150001)

机构地区：[1]北京动力机械研究所,北京100074 [2]西安热工研究院有限公司,陕西西安710054 [3]火箭军装备部驻北京地区第六代表室,北京100074 [4]哈尔滨工业大学能源科学与工程学院,黑龙江哈尔滨150001

出　　处：《热能动力工程》2022年第9期120-127,135,共9页Journal of Engineering for Thermal Energy and Power

摘　　要：某电厂4号墙式布置机组燃用无烟煤和贫煤混煤,炉膛出口NO_(x)排放质量浓度高达1272 mg/m^(3)(6%O_(2)),采取中心给粉旋流燃烧器(CFR)和两层燃尽风对其燃烧系统进行低NO_(x)技术改造。采用数值仿真和改造后工业试验相结合的方法,研究了改造方案可行性。结果显示:不同燃尽风(OFA)风率条件下,低挥发分煤均能实现稳定燃烧;随OFA风率增加,主燃区化学当量比减小,O_(2)质量分数降低,燃烧反应速度降低,高温区域范围呈缩小趋势,温度沿炉高分布更为均衡,主燃区相对低温贫氧氛围有效抑制了低挥发分煤燃烧条件下的NO_(x)生成;27.50%的OFA风率条件时,炉内温度分布均衡,NO_(x)排放质量浓度845.1 mg/m^(3),最终选定的OFA风率为27.50%。改造后工业试验显示,NO_(x)排放质量浓度降为833.4 mg/m^(3),降幅达34.5%。数值仿真结果和改造后工业试验数据相吻合,证明机组低NO_(x)技术改造方案可行。Low-volatile coal of anthracite and lean coal was the design coal of No.4 wall-fired boiler in the power plant,NO_(x) emission of furnace outlet was 1272 mg/m^(3)(6%O_(2)).Centrally fuel rich(CFR)swirl burner and two-layer over-fire air(OFA)system were adopted for the combustion system during the low NO_(x) technical transformation.The numerical simulation method combining with industrial test data was adopted to study the feasibility of reconstruction scheme.The results show that steady combustion of the low-volatile coal can be achieved at different OFA rates.The chemical equivalence ratio,O_(2) mass fraction and combustion reaction speed of primary combustion zone decrease with the increase of OFA rate.In this way,the area of high-temperature zone declines,temperature profile is more uniform along furnace height direction.Under the relatively oxygen-depleted and low-temperature atmosphere,NO_(x) emission from the low-volatile coal is restrained in the primary combustion zone effectively.The temperature field of furnace is evenly distributed,and NO_(x) emission is 845.1 mg/m^(3)at 27.50%OFA rate,so the finally selected OFA rate is 27.50%.After reconstruction,the industrial test shows that NO_(x) emission is 833.4 mg/m^(3),reduced by 34.5%.Numerical simulation result is consistent with industrial test data,which proves that the low NO_(x) technical reconstruction scheme of the unit is feasible.

关 键 词：锅炉 中心给粉 低挥发分 数值模拟 NO_(x)排放 

分 类 号：TK16[动力工程及工程热物理—热能工程]