Study on nitrogen oxides reduction by advanced biomass reburning process
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摘要: 在沉降炉上研究草本类棉秆、玉米秸、麦秆和木本类梧桐木四种生物质的先进再燃脱硝特性。结果表明，20%再燃比、0.7s停留时间能保证较优的反应工况。在过量空气系数为0.7～0.9、氨氮摩尔比为1.5左右时，棉杆、玉米秸、麦秆以及梧桐木先进再燃在1273K附近取得最高脱硝效率，其值分别为89.11%、88.34%、90.33%和88.28%，比基本再燃提高25%～30%，并且生物质的再燃反应是脱硝的主体，喷氨是对再燃的完善和优化。在1173K~1473K四种生物质的先进再燃可以保持80%以上的脱硝效率。实验过程中加入100×10-6的碱金属、碱土金属添加剂可进一步改良先进再燃脱硝进程。碳酸钠、碳酸钾使脱硝效率提高3%~6%；醋酸钙在1273K~1473K将脱硝率提高4.0%~5.0%，在1073K~1273K作用规律不明显。Abstract: Advanced reburning (AR) tests were conducted in a vertical-tube experimental system using herbaceous biomass of cotton-haulm, corn-stalk, wheat-stalk and woody biomass of phoenix tree as reburning fuels. The results show that the Rff of 20% and residence time of 0.7s are better for the reburning process. When the excess air ratio ranges from 0.7 to 0.9, and NH3/NO mol ratio (NSR) is about 1.5, the maximum efficiency of nitrogen oxides (NOx) reduction at 1273K by cotton-haulm, corn-stalk, wheat-stalk and phoenix reburning reaches 89.11%, 88.34%, 90.33% and 88.28%, respectively, which is 25%~30% higher than that by general reburning. It indicates that the biomass reburning plays a great role for the NOx reduction in AR and the ammonia-ejection plays a role for optimizing the course. In a broad range of 1173K~1473K, the AR of all tested biomass could gain NOx reduction beyond 80%. The NOx reduction can be further meliorated by adding alkali metals and alkaline earth promoters with 100×10-6 vol concentration, and the promoting effect differs from each other. The sodium carbonate and potassium carbonate can enhance the efficiency by 3%~6%; and the calcium acetate can enhance the efficiency by 4.0%~5.0% at 1273K~1473K but by nothing at 1073K~1273K.
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Key words:
- biomass /
- dvanced reburning /
- xcess air ratio /
- NSR /
- romoter
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