由于循环流化床（ CFB）锅炉特有的结构和燃烧方式，其氮氧化物排放低于其它炉型，有清洁炉型之称，但随着烟气污染物排放标准的进一步提高，其氮氧化物的排放已不能满足新的排放需要。选择性非催化还原法（ SNCR ）工艺＋低氮燃烧（ LNB ）脱硝技术具有投资费用少、运行成本低、锅炉改造范围小等优势，而CFB锅炉具有烟气在炉内停留时间长、便于还原剂在炉内混合等特点，该脱硝改造两步法在小型循环流化床锅炉脱硝改造中被广泛应用。本文以75 t／h循环流化床锅炉为模型，并采用环保性较高的尿素作为脱硝还原剂，通过低氮燃烧（ LNB）＋SNCR工艺两步法脱硝技术改造方式，进一步提高脱硝效率，并对锅炉进行针对性的改进以提高其出力，最终使烟气中NOx排放达到新的国家标准要求。主要从实施背景、技术路线、疑难问题解决及改造后的效果分析、存在问题等进行分析探讨。%Because of the circulating fluidized bed ( CFB ) boiler′s own specific structure and combustion way, the nitrogen oxide emission is lower than other type furnace , which is regarded as clean furnace type.However, with the increase of flue gas pollutants emission standards , the nitrogen oxide emissions cannot meet the needs of the new emissions .Since selective non-catalytic reduction(SNCR)+low nitro-gen combustion ( LNB) denitration technology has the advantages of low investment and operation cost , small boiler retrofit , and the CFB boiler is easy for flue gas to stay in furnace for a long time and easy for reducing agent to be mixed in the oven etc , the denitration modified two-step in small circulating fluidized bed boiler denitration transformation is widely used .Taking 75t/h circulating fluidized bed boiler as a model , this paper describes using the environmental protection high urea as the denitration reducing agent by the low nitrogen combustion ( LNB) +SNCR process two-step denitration technology , and improving the denitration efficiency and the boiler′s output by targeted improvements , which eventually make the NOx in flue gas emissions to meet the new national standard requirements .This paper is mainly from the implementation background , technical route , difficult problem solving , and the effect after transforming analysis, and existing problems to analyze and discuss .
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