加氢装置高压换热器在线水洗除盐实践

Practice of on-line water cleaning for HP heat exchangers in hydrogenation unit

中国石油化工股份有限公司广州分公司2.0 Mt/a柴油加氢改质装置在实际生产中,当原料氯质量分数大于0.5μg/g、氮质量分数大于700μg/g时,生成的氯化铵易在反应系统高温高压换热器部位形成铵盐结晶,引起换热器E9102压差升高,影响装置安全生产.通过降低反应温度和装置负荷、增加注水点,部分产品循环加氢等方式来满足注水时降温的要求,通过调整分馏系统操作防止注水对汽提系统造成影响,实现了加氢装置高温高压换热器在线清洗铵盐结晶,避免了装置停工.水洗后,装置进入正常高负荷运行阶段,循环氢量恢复到正常值240～250 dam3/h,换热器压差明显下降,并基本维持在0.18～0.19 MPa,较水洗前降低约0.37 MPa,达到了开工初期水平.同时水洗期间产品质量能达到国Ⅲ柴油标准的要求.

In the operation of the 2.0 MM TPY diesel hydro-upgrading unit in SINOPEC Guangzhou Company when the chloride in the feedstock was greater than 0.5 ppm and nitrogen was higher than 700 ppm,it was easy for ammonium chloride to form ammonium salt crystallization in high-temperature high-pressure heat exchanger of hydrogenation unit,which led to the increase of heat exchanger＇ s differential pressure and affected the normal production of the unit.The ammonium salt crystallization problem has been solved by online water cleaning of HT HP heat exchangers through reduction of reaction temperature,lowering of unit capacity,addition of water injection points,recycle of part of products to reduce the temperature during water injection as well as through adjustment of fractionator operation to prevent the impact of water injection on the stripping system.After water cleaning,the recycle hydrogen is restored to its normal 240 ～250 dam3/h,the pressure difference of heat exchanger E9102 is obviously lowered and maintained at 0.18 ～0.19 MPa,which is 0.37 MPa lower than that before water cleaning and at the same level in the early stage of start-up of the unit.During online water cleaning,the product＇ s quality reached Chinese Guo Ⅲ diesel standard.