蒸馏装置减压深拔问题分析及对策

Problem analysis and countermeasures of the vacuum deep extraction in distillation unit

关键词:  常减压蒸馏装置  减压深拔  结焦  填料  润湿量  柴油吸收  有机硫

Key words:  atmospheric and vacuum distillation unit  vacuum deep extraction  coking  packing  quantity of wetting  diesel absorption  organic sulfur

摘要:

年,中国石油独山子石化分公司常减压蒸馏装置洗涤油泵出现抽空现象。为防止泵抽空,只能将洗涤油罐满罐操作。2019年大修时,发现减三线回流过滤器丝网破损,减压塔内减三线回流主管、分配管油泥较多,且越靠近主管末端,油泥越多。减压塔洗涤段共6层填料,从上至下填料结焦逐步加重。洗涤油集油槽槽内和抽出口焦粉、碎焦块均较多。结合大修时的检查情况,对洗涤油泵抽空及洗涤段填料层结焦的原因进行分析,制定了减缓填料层结焦的措施:①大修时对洗涤段填料进行全部更换,对减三线回流管进行清理；②生产过程中定期对减三线回流过滤器进行检查清理,严格控制洗涤段填料润湿量,提高常压拔出率。实施减压深拔时,减压塔进料温度高,渣油裂解反应加剧,导致减顶瓦斯量上升,减顶瓦斯中有机硫含量高,导致减压炉排放烟气中SO₂质量浓度超标。因此,减顶瓦斯脱硫系统增加了柴油吸收措施,有效降低了减顶瓦斯中的有机硫和总硫含量,顺利实现了减压炉烟气达标排放。 

Abstract:

In 2017, cavitation occurred in the washing oil pump of the atmospheric and vacuum distillation unit. In order to prevent pump cavitation, the washing oil tank was operated with full liquid level. During the overhaul in 2019, it was found that the steel net of third line reflux filter was broken. There was more oil sludge in the third line reflux main and distribution pipe of the vacuum column. The closer it was to the end of the main pipe, the more oil sludge there was. There were 6 layers of packing in the washing section of vacuum column, and coking gradually increased from top to bottom. There were more coke powder and broken coke blocks in the washing oil collection tank and extraction outlet. Combined with the situation of overhaul, the reasons of washing oil pump cavitation and coking of packing layer in washing section were analyzed, and the measures to reduce coking of packing layer were formulated:(1) Replace all the packings in the washing section and clean up the third line reflux pipe during the overhaul. (2) During the production process, the third line reflux filter was checked and cleaned regularly, the wetting amount of the washing section packing was strictly controlled, and the atmospheric extraction rate was improved. During the implementation of vacuum deep extraction, the feed temperature of vacuum column was high and the residual oil cracking reaction was intensified, which led to the increase of vacuum top gas flow. The high content of organic sulfur in vacuum top gas led to the SO₂ mass concentration in the flue gas of vacuum furnace exceeding standard. Therefore, diesel absorption measures were added to desulfurization system of vacuum top gas, which effectively reduced the content of organic sulfur and total sulfur in vacuum top gas, and successfully achieved the standard emission of the flue gas of vacuum furnace.