生物质高级再燃脱硝的影响因素与元素释放特性

以稻壳(RH)、梧桐叶(PTL)和木屑(SD)为对象,利用携带流脱硝实验装置,研究了生物质种类、再燃反应温度(t2)、再燃区化学计量比(SR2)、喷氨位置、水蒸气以及添加剂等对生物质高级再燃(AR)脱硝效率的影响,分析了高级再燃过程中钾和氯等元素的释放特性。结果表明,在t2为850~1 150℃,随着t2升高,生物质高级再燃脱硝效率呈现先上升后下降的趋势。在SR2为0.5~1.0,随着SR2增加,稻壳高级再燃脱硝效率呈现先增加后降低的趋势。停留时间为0.4~1.0 s,氨气添加位置对稻壳高级再燃脱硝效率有一定的影响,但其效果并不明显。烟气中水蒸气含量(0~15%)可提高稻壳高级再燃的脱硝效率,而且可拓宽脱硝温度窗口。不同再燃温度下,4%水蒸气含量模拟烟气的脱硝效率最大。添加剂(Fe2O3、KCl、NaCl和CaO)对稻壳高级再燃脱硝均有促进作用,其中,Fe2O3促进作用最为显著。在稻壳高级再燃过程中,氯和钾元素释放率分别达到95.0%和59.8%以上。

Influence factors and element release properties during NO reduction through biomass advanced reburning

NO reduction through advanced reburning (AR) with biomass including rice husk (RH), phoenix tree leaves (PTL) and saw dust (SD) was tested in an entrained flow reactor (EFR). The effects of reburning fuel species, reaction temperature in the reburning-zone (t₂), the location of ammonia injection, water vapor and additives on the NO reduction were investigated. Furthermore, the migration of chloride and potassium elements during biomass advanced reburning was examined. The results indicate that the NO removal efficiency via biomass advanced reburning shows a tendency of increase first and decrease later with increasing the reaction temperature in the reburning-zone from 850 ℃ to 1 150 ℃. The same tendency is also found as SR₂ increases from 0.5 to 1.0. The location of ammonia injection has a certain influence on the NO reduction with rice husk when the residence time is in the range of 0.4~1.0 s. The water vapor (0~15%) in the flue gas not only improves the NO removal efficiency, but also broadens the window temperature of DeNO_x, and the best NO removal efficiency can be obtained when the water vapor is about 4%. Additives (Fe₂O₃, KCl, NaCl and CaO) have a better promoting effects on the NO reduction through advanced reburning with rice husk, in which Fe₂O₃ shows the most significant effect on the NO reduction. The release of chlorine and potassium during advanced reburning with rice husk can reach more than 95.0% and 59.8%, respectively.