Abstract: The industrial application of selective catalytic reduction (SCR) and selective non catalytic reduction (SNCR) combined technology for denitration in a 3.5 MM TPY FCC unit of a refinery is introduced. The effects of reaction temperature, ammonia injection flow, atomization effect and flow field distribution on denitration efficiency are investigated. With the increase of reaction temperature, NOx removal rate increases to the maximum and then decreases. When ammonia passes through the upper spray gun, the optimal furnace temperature is 810 ℃, the corresponding optimal furnace temperature of the lower spray gun is 800 ℃, and the furnace temperature is 775~825 ℃, the denitration rate reaches a good level. At this time, the volume fraction of CO in the regeneration flue gas is 4.2%~4.8%. With the increase of ammonia injection flow, the denitration efficiency increases, but the ammonia escape amount of the discharged flue gas also increases. When the ammonia injection flow is less than 260 kg/h, the denitration efficiency is high, and the ammonia escape amount can meet the requirements. When the ammonia atomization pressure is greater than 0.25 MPa, it can meet the SNCR atomization requirements. All burners are put into operation to ensure uniform flow field and improve denitration efficiency. When the reaction temperature is 823 ℃, the ammonia injection flow is 106 kg/t and all burners are put into operation, the mass concentration of NOx in the discharged flue gas is 102 mg/m³, the ammonia escape amount is 1.04 mg/m³, and the NOx removal rate reaches 56.77%. The SNCR denitration technology can meet the requirements of NOx environmental protection in lean oxygen regeneration FCC unit.

Key words: lean oxygen regeneration, FCC unit, SNCR, reaction temperature, denitration efficiency, atomization effect, ammonia injection flow, flow field distribution

摘要： 介绍了某炼化企业3.5 Mt/a催化裂化装置采用选择性催化还原法（SCR）和选择性非催化还原法（SNCR）组合技术进行脱硝的工业应用情况，考察了反应温度、喷氨量、雾化效果、流场分布对脱硝效率影响。结果表明：随着反应温度升高，NOx脱除率先增加至最大值后降低，当氨水通过上层喷枪时最佳炉膛温度为810 ℃，下层喷枪对应最佳炉膛温度为800 ℃，炉膛温度范围为775～825 ℃时，脱硝效率达到较好水平，此时，对应再生烟气中CO体积分数为4.2%～4.8%；随着喷氨量增加，脱硝效率增加，但是外排烟气氨逃逸量也随之增大，当喷氨量小于260 kg/h时，脱硝效率较高，同时可满足氨逃逸要求；氨水雾化压力大于0.25 MPa时，可满足SNCR雾化要求；燃烧器全部投用，确保流场均匀，可提高脱硝效率。标定结果表明：当反应温度为823 ℃、喷氨量为106 kg/t、燃烧器全部投用情况下，外排烟气NOx的质量浓度为102 mg/m³，氨逃逸量为1.04 mg/m³，NOx脱除率达到56.77%，使用SNCR脱硝技术在贫氧再生催化裂化装置可满足NOx环保指标要求。

关键词: 贫氧再生, 催化裂化装置, SNCR, 反应温度, 脱硝效率, 雾化效果, 喷氨量, 流场分布