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针对330 MW贫煤锅炉开展了低氮燃烧系统的现场试验,研究了炉膛出口以及SCR前后的NO_x排放情况,还考查了NO_x浓度随烟道深度和锅炉负荷的变化情况。结果表明:炉膛出口的NO_x浓度基本维持在600 mg/m~3左右。NO_x排放浓度与取样位置有关,现场检测NO_x时要在断面合理布点。在炉内低氮燃烧+SCR共同控制下,贫煤锅炉在不同负荷下都可实现烟气出口NO_x浓度≤50 mg/m~3。SCR系统正常运行情况下脱硝效果较好,但存在氨耗量较大,催化剂堵塞、磨损、低负荷情况脱硝效率较低等问题,建议对于贫煤机组可以采用SNCR+SCR的联合脱硝方法,增加氨气在系统内停留时间,提高脱硝效率,避免氨逃逸。
A field test of a low nitrogen combustion system was carried out for a 330 MW lean coal fired boiler. The emission of NO x before and after the furnace exit and before and after the furnace was studied. The variation of NO x concentration with the depth of the chimney and the boiler load was also examined. The results show that the NO_x concentration at the outlet of the furnace basically keeps at about 600 mg / m ~ 3. NO_x emission concentration and the sampling location, on-site detection of NO_x reasonable distribution point in the section. Under the common control of low nitrogen combustion + SCR in the furnace, the lean coal boiler can realize NO_x concentration ≤50 mg / m ~ 3 under different loads. SCR system has better denitrification effect under normal operation, but there are some problems such as larger ammonia consumption, clogging and abrasion of the catalyst and lower denitrification efficiency under low load conditions. It is suggested that SNCR + SCR combined denitrification method should be adopted to increase the Ammonia residence time in the system to improve denitration efficiency, to avoid ammonia escape.