Abstract: The problems existing in the air system of propane dehydrogenation unit are described, and the causes of the problems are analyzed. The research results show that the nitrogen oxides (NO_x) in the flue gas at the chimney outlet is mainly produced by the air heating furnace, and the main pollutant in the flue gas of heating furnace outlet is NO, the main pollutant in the flue gas after catalytic dehydrogenation is NO₂, selective catalytic reduction (SCR) can effectively reduce the concentration of NO_x. The blockage of the SCR denitration catalyst pores causes the increase of bed pressure difference and the decrease of denitration efficiency. The denitration activity can be recovered by disassembling the catalyst module for purging. The efficiency of a domestic denitration catalysts is lower than that of imported one, and a specific catalyst is needed for denitration of air system. Through optimization and transformation, the inlet cone section of the waste heat boiler is replaced with a Pyro-Bloc fiber module to avoid damage of the inner insulation layer of the inlet cone section and solve the problem of over temperature on the surface of the cone section; the non-metallic expansion joint is replaced by metal expansion joint to avoid the leakage of high-temperature flue gas and maintain long-term operation of the air system.

Key words: propane dehydrogenation unit, air system, nitrogen oxides, non-metallic expansion joint, SCR denitration catalyst, surface over temperature

摘要： 阐述了某公司丙烷脱氢装置空气系统中存在的问题,分析了问题产生的原因。结果表明:烟囱排放口烟气中 NO_x主要产生于空气加热炉,加热炉出口烟气中污染物以NO为主,经过催化脱氢后烟气中污染物以NO₂为主,选择性催化还原(SCR)催化脱硝能够有效降低NO_x的浓度。SCR脱硝催化剂孔道堵塞,致使床层压差升高、脱硝效率下降,拆开催化剂模块进行吹扫能恢复其脱硝活性。某国产脱硝催化剂的效率低于进口脱硝催化剂,空气系统脱硝需要专一性强的催化剂。通过优化改造,将余热锅炉入口锥段改用派罗块纤维模块,避免入口锥段内保温层损坏,同时解决了锥段表面超温的问题;将非金属膨胀节改为金属膨胀节,避免了高温烟气泄漏,保证空气系统长周期运行。

关键词: 丙烷脱氢装置, 空气系统, 氮氧化物, 非金属膨胀节, SCR脱硝催化剂, 表面超温