生物质先进再燃脱硝特性研究

Study on nitrogen oxides reduction by advanced biomass reburning process

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。

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.