常规SNCR（非选择性催化还原)是在850~1 100 ℃的烟气中喷入氨基还原剂，实现降低NOx的目的。另外，SNCR也可以拓展到低氧的条件下，实现较高温度下脱硝，即主燃区喷氨技术。本文将主燃区喷氨技术应用到75 t/h四角切圆煤粉锅炉中，与OFA（空气分级）、SNCR协同实现深度脱硝，实验结果表明：在OFA基础上采用主燃区喷氨技术时，随着氨氮比NSR1的增加，NOx排放浓度有明显降低，最佳氨氮比NSR1=1.73，比单一用OFA时还原效率提高了21.9%，无氨逃逸产生；仅采用SNCR技术时，最佳氨氮比NSR2=1.84，在OFA的基础上NOx还原效率提高了40.4%，当NSR2＞1.84时出现氨逃逸现象；在SNCR脱硝效果有限的条件下，在主燃区喷入氨还原剂可进一步降低NOx排放，还原效率可提高17%，并无氨逃逸存在；在SNCR还原效果受限时，主燃区喷氨技术与SNCR协同可实现炉内深度脱硝，并避免氨逃逸问题。

Conventional SNCR(selective non-catalytic reduction) is used to reduce NOx by injecting ammonia into the flue gas of temperature in 850-1 100℃.Additionally,ammonia injection in the primary combustion zone can achieve the goal of denitration with higher temperatures in hypoxic conditions.In this paper,the technology of ammonia injection in the primary zone was applied and combined with SNCR and OFA in a 75 t/h tangential pulverized coal boiler to obtain deeper denitration. The test results showed that,when ammonia injection in the primary zone is applied based on OFA,NOx emission concentration is lower with the increase of NSR1(normalized stoichiometric ratio),and the optimum NSR1 is 1.73 without ammonia slip. The NOx reduction efficiency is 21.9% higher than that by using OFA only.With SNCR only,the optimum NSR2 is 1.84,and the reduction efficiency is increased by 40.4% than that of OFA only.With NSR2 > 1.84,there is serious ammonia leakage.Injecting ammonia into the primary combustion zone based on OFA can further reduce NOx when SNCR denitration effect is limited; reducing efficiency can be increased by 17% without ammonia slip.That is,when SNCR denitration is limited,combining both technologies can realize the deeper denitration in PC-boiler without ammonia slip.

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