蒸汽过热炉烟气中氮氧化物的来源及减排措施

Sources of NOx in Flue Gas of Steam Superheater and Measures for Emission Reduction

结合苯乙烯生产装置蒸汽过热炉运行过程,探讨了过热炉烟气中NOx的来源,通过数据分析剖析了造成装置NOx排放值高的主要影响因素,并提出了改进措施。结果表明:蒸汽过热炉炉膛中的氧含量高、燃料气中的氮含量高、燃料气压力低等因素是造成装置NOx排放值高的主要原因。通过控制过热炉氧体积分数在2.5%~3.0%,将过热炉B室火嘴更换为小口径火嘴、优化燃料气流程等措施后,燃料气压力提高至28 kPa,炉膛火焰分布均匀,燃烧充分,装置排放烟气中NOx浓度由137 mg/m^3降低至80 mg/m^3,低于国标特别排放限值要求,烟气实现达标排放。

This paper introduced the formation mechanism of nitrogen oxide(NOx)in the flue gas,and discussed the sources of NOx in the flue gas of steam superheater along with its operation process in the styrene plant.The results showed that the high oxygen content in steam superheater,nitrogen content in fuel gas and low pressure were the main reasons for the high NOx emission.By controlling oxygen volume fraction at 2.5%~3.0%in the superheater,replacing the burner in chamber B of the superheater with a small-bore burner,and optimizing fuel gas flow,among other technological improvements,the fuel gas pressure increased up to 28 kPa with uniform flame distribution and full combustion achieved in the superheater,and the NOx concentration in flue gas discharged from the plant decreased from 137 mg/m3 to 80 mg/m3,which was lower than the special emission limit required by national standard,realizing up-to-standard emission for the flue gas.