粉体对分解炉内SNCR反应影响的研究

Influence of calcium-based particles on the selective non-catalytic reduction process in a pre-calciner

采用滴管炉反应器,针对钙基粉体对分解炉环境下SNCR反应的影响进行了研究。考察了NH3和尿素两种还原剂对不同温度(600～1 100℃)、氨氮比(0.5～2.0)和氧浓度(0.5%～5.0%)下SNCR反应的影响。实验结果表明,生料、CaO和CaCO3三种粉体都对分解炉条件下两种还原剂的SNCR反应均有抑制作用,低温下粉体的抑制作用较为明显,高温下粉体的抑制逐渐减弱。低温下生料的抑制作用强于CaCO3和CaO,主要是生料中活性杂质的催化作用;高温下CaO的抑制作用最强,之后是CaCO3和生料。随着氨氮比的增加,SNCR脱硝效率增强,粉体对脱硝效率的抑制程度基本不变。生料的最佳脱硝氧浓度为1%,而CaCO3和CaO的最佳脱硝氧浓度为2%。有粉体存在下的SNCR反应特性是气相脱硝反应与还原剂气固催化氧化反应竞争的结果。

The influence of calcium-based particles on the selective non-catalytic reduction （SNCR） process was investigated in a drop tube fu_rnace reactor; the tests under different temperatures （600 - 1 100 ℃ ）, normalized stoichiometric ratio （NSR） of NH3/NO （0.5 - 2.0） and O2 concentrations （0.5% - 5.0% ）, with ammonia and urea as reducing agents, were considered. The results showed that the raw material, CaCO3 and CaO have inhibitive effect on the SNCR performance; the extent of this effect is significant at low temperature but attenuates with the increase of temperature. Raw material exhibits the strongest inhibitive effect on the SNCR at low temperature because of the catalytic activity of impurity in the raw materials, while CaO has the strongest effect at high temperature. The efficiency of SNCR is increased by increasing NSR, while the effect of calcium- based particles on SNCR remains unchanged. The optimal 02 concentrations for NOx removal is 1% with raw material and 2% with CaCO3 and CaO. The SNCR performance in the presence of calcium-based particles is characterized by the competition of denitration reactions between gaseous de-NOx and the particle-catalyzed oxidation of reductant.