丙酸钙再燃的脱硝特性

Nitric oxide reduction through calcium propionate reburning

在沉降炉实验台上系统地研究了丙酸钙的再燃脱硝特性。丙酸钙基本再燃可以取得与液化石油气相当的脱硝效率。实验结果表明:在973～1 323 K,丙酸钙基本再燃的脱硝效率与温度同步升高,最高为79.65%,此后进一步升高温度,效率提高不明显;为保证基本再燃较高的脱硝效率,烟气中初始氧浓度不宜超过5%,再燃比应在25%附近,同时停留时间应保证在0.7 s左右。单独喷氨气的选择性非催化还原能取得的最高脱硝效率为1 273 K时的85.34%,但"温度窗口"较窄,为1 215～1 341 K,适宜氨氮摩尔比为1.75～2.00。在先进再燃过程中,由于丙酸钙和氨气存在协同的脱硝作用,这两种试剂的所需加入量大大减少,当再燃比为19.83%,氨氮摩尔比为0.8时,其最高效率可达到93.37%,同时"温度窗口"拓宽为1 195～1 355 K,而且在2%～6%的氧浓度范围内,先进再燃均能保持较高的脱硝效率。

The characteristics of nitric oxide（NO） reduction using calcium propionate（CP） were investigated in a drop tube experimental system.It is demonstrated that the calcium propionate basic reburning（BR） can get the NO reduction efficiency in comparable with liquefied petroleum gas.From 973 K to 1 323 K,the NO reduction efficiency of CP-BR increase with temperature and the highest value is 79.65%.When temperature is further increased,the efficiency is improved little.For a satisfying outcome of the CP-BR,oxygen concentration in flue gas should not be above 5%,reburning fuel fraction（α） and residence time should be kept about 25% and 0.7 s,respectively.When ammonia is injected alone,namely selective non-catalytic reduction（SNCR）,the maximum NO reduction efficiency of 85.34% is achieved at 1 273 K and the ＂temperature window＂ of 1 215 K to 1 341 K is narrow.Also,the quantity of ammonia injection is large whose corresponding mole ratio of ammonia to NO（ε） is required between 1.75 and 2.00.During the advanced reburning（AR） process,the calcium propionate and ammonia work synergistically and the injection of these two reagents is reduced for high NO reduction efficiency.When α and ε are fixed at 19.83% and 0.8,the maximum of AR efficiency is 93.37%.At the same time,the ＂temperature window＂ is broadened to 1 195~1 355 K and the efficiency isnt obviously impacted between 2% and 6% of the oxygen concentration.