分馏塔结盐原因分析及应对措施

催化裂化原料中有氯和氮存在,在高温条件下HCl气体不断逸出,同时催化裂化原料中的氮化物在催化裂化反应条件下,在催化裂化分馏塔内形成NH4Cl.分馏塔内随着油气不断上升,而分馏温度下降,NH4Cl结晶的速度越快,同时在设备表面的NH4Cl晶体也聚积越多,最终导致降液管流通面积减小,直至堵塞降液管,造成塔盘液层增厚,导致分馏效果变得很差,造成产品质量不合格.根据NH4Cl易溶于热水的原理,采用在线水洗的方法,去除结盐,恢复生产,降低成本,提升经济效益.

Analysis and Countermeasures of Salt Precipitation in Fractionating Tower

There is chlorine and nitrogen in catalytic cracking materials,hydrogen chloride continuously escapes at high temperature,then ammonium chloride is formed from nitride in catalytic cracking material and hydrogen chloride in fractionating tower under the catalytic cracking reaction conditions.With the rising of oil and gas,fractionation temperature decreases in fractionation tower,the crystallization rate of NH4Cl becomes fast,more NH4Cl crystals accumulate on surfaces of the device,eventually circulation area of the downcomer decreases until the downcomer is plugged,which can cause tray liquid layer thicken and the fractionation effect become poor to result in product quality disqualification.According to the principle that NH4Cl is easy to be dissolved in water,the online washing method may be used to remove salt to restore production,which can reduce cost and improve economic efficiency.