电厂实际运行中发现，水蒸气能够降低选择性非催化还原反应(SNCR)烟气脱硝过程中脱硝剂的用量，对脱硝和燃烧产生一定的促进作用。围绕水蒸气在不同脱硝技术中的作用效果和反应机理，对相关文献进行总结。研究发现，水蒸气对SNCR脱硝、再燃脱硝以及先进再燃脱硝技术均有促进强化作用。水蒸气的加入能促进SNCR脱硝反应中OH自由基的产生，可与NH₃还原剂反应生成NH₂基团，从而提高脱硝效率。水蒸气对再燃脱硝的促进作用，主要通过提高挥发分中HCN、NH₃等析出促进NO还原。添加水蒸气可以使先进再燃技术的脱硝效率提高到80%以上，水蒸气对生物质先进再燃脱硝与对再燃脱硝的作用机理类似，而对煤粉先进再燃作用机理不详。综上，水蒸气对先进再燃脱硝的作用机理应包括对SNCR脱硝与再燃脱硝2部分的共同促进作用及2者之间的相互作用，但目前研究较少关注水蒸气对再燃燃料的影响。应进一步研究水蒸气对先进再燃脱硝的作用机理和操作条件，为水蒸气在脱硝技术中的应用提供有力理论支撑。

During the actual operation of the power plant, it was found that the addition of water vapor can reduce the amount of denitrifying agent used in the SNCR denitration reaction, which has a certain promotion effect on denitrification and also promotes the combustion process. Therefore, studying the influence and mechanism of water vapor on various denitration technologies is of great significance for achieving low-cost and high-efficiency denitration. This paper analyzed and summarized relevant literature reports focusing on the promotion effect and mechanism of water vapor in the denitration reaction. The study found that water vapor indeed can promote the denitration of SNCR, reburning and advanced reburning technologies, but there is no consistent conclusion on the optimal amount of water vapor. The denitration efficiency improvement of adding water vapor in biomass reburning and its advanced reburning were a little smaller than that in pulverized coal reburning, and advanced reburning. The addition of water vapor can effectively promote the generation of OH groups in the SNCR denitration reaction, which can react with the NH3 reducing agent to generate NH₂ groups, thereby improving its denitration efficiency. The promotion effect of water vapor on reburning is mainly through the formation of OH groups, which increases the volatiles, especially the precipitation of HCN, NH₃, etc., thereby promoting NO reduction. Adding water vapor can increase the denitrification efficiency of advanced reburning technology to more than 80%, it is considered that the denitration mechanism of advanced reburning of biomass by water vapor is similar to the denitration mechanism of reburning, while, the mechanism of advanced reburning of coal powder by water vapor has not been reported. In summary, the influence mechanism of water vapor on advanced reburning should include the both SNCR and the fuel reburning and the interaction between them. However, the current research has not paid attention to the influence on the solid fuel reburning, especially the effects on reduction of NO by coke. Therefore, the influence mechanism and operating conditions of water vapor on advanced reburning and the best reaction conditions should be further studied to provide a strong theoretical support for the application of water vapor in practical.

0 引言

1 燃煤锅炉中水蒸气的应用与研究

   1.1 水蒸气对烟气中CO、CO2浓度变化的影响

   1.2 水蒸气对烟气中NO_x浓度变化的影响

2 水蒸气对SNCR脱硝效果影响及机理研究

   2.1 选择性非催化还原（SNCR）技术

   2.2 水蒸气对SNCR脱硝效果的影响

   2.3 水蒸气对SNCR脱硝效果数值模拟研究

3 水蒸气对再燃脱硝效果影响及机理研究

   3.1 再燃技术

   3.2 水蒸气对煤粉再燃还原NO的影响

   3.3 水蒸气对生物质再燃脱硝效果的影响

   3.4 水蒸气对沼气再燃过程中重要中间组分的影响

4 水蒸气对先进再燃脱硝效果的影响

   4.1 先进再燃技术

   4.2 水蒸气对天然气先进再燃脱硝效果的影响

   4.3 水蒸气对生物质高级再燃脱硝效果的影响

5 结语与展望