为提高选择性非催化还原反应（SNCR）脱硝效率，实现SNCR宽负荷脱硝，以1台130 t/h CFB（循环流化床）锅炉为研究对象，进行低氮燃烧调整试验，通过研究分离器温度控制机理，探究影响分离器温度的影响因素，研究分离器出口温度Tsep控制方法。结果表明：SNCR温度窗口存在1个高效反应温度点Topt，将分离器出口温度精准控制在Topt附近可获得更高的SNCR脱硝效率；烟气再循环（FGR）对分离器Tsep具有调节作用，分别在130、90、70 t/h负荷投入FGR，分离器温度分别提高了30、40、70 ℃，随负荷降低，FGR对分离器温度的调控能力增强；上、下二次风比例对Tsep同样起调节作用，通过切换上、下层二次风门，Tsep的调节范围约为30 ℃；Tsep随一次风率的提高而降低，在4.5% 氧量下，Tsep的调节幅度为18 ℃；在3.5%氧量下，Tsep的调节幅度为35 ℃，低氧量下一次风率对Tsep的调节范围更大：锅炉110～130 t/h负荷期间，经分离器温度精准控制在(850±5)℃后，质量分数20%氨水由350 kg/h降低至200 kg/h。实炉应用表明，分离器温度控制技术可以在高负荷时优化SNCR反应效率，降低脱硝运行成本，低负荷时可将停止的SNCR反应重启，实现NOx达标排放，节约氨水费用280万元。

In order to improve the efficiency of SNCR denitrification and realize SNCR denitrification with wide load,a low nitrogen combustion adjustment test was carried out on a 130 t/h CFB boiler. Through the research on the temperature control mechanism of the separator,the influencing factors affecting the temperature of the separator were explored,and the control method of separator outlet temperature(Tsep)were studied. The results show that,there is a most efficient reaction temperature point Topt,in the SNCR temperature window. Higher SNCR denitration efficiency can be obtained by precisely controlling the Tsep around Topt. Flue gas recirculation (FGR) can adjust Tsep. FGR is put into operation at 130,90 and 70 t/h respectively,and the separator temperature is increased by 30，40 and 70 ℃. With the decrease of boiler load,the control ability of FGR to Tsep is enhanced. The ratio of upper and lower secondary air also also can adjust Tsep. By switching the upper and lower secondary air,The change range of Tsep is about 30 ℃. Tsep decreases with the increase of primary air rate,the adjustment range of Tsep is 18 ℃ at 4.5% oxygen content and the adjustment range of Tsep is 35 ℃ at 3.5% oxygen content,and the regulation range of primary air rate on Tsep is larger under low oxygen content. During the boiler load of 110-130 t/h,after the separator temperature is accurately controlled at (850±5) ℃,the 20% mass concentration of ammonia is reduced from 350 kg/h to 200 kg/h. The practical application shows that the separator temperature control technology can optimize the SNCR reaction efficiency at high load,and reduce the operation cost of denitration,restart the SNCR reaction at low load to achieve NOx emission standard,save 2.8 million yuan of ammonia cost.

0 引言

1 研究对象

2 研究方法

   2.1 分离器温度控制机理

   2.2 分离器温度控制方法

3 分离器温度影响因素

   3.1 FGR对分离器温度的影响

   3.2 二次风对分离器温度的影响

   3.3 一次风对分离器温度的影响

4 分离器温度控制的应用

5 结论