关键词: 润滑油加氢, 高压换热器, 铵盐结晶, 垢下腐蚀, 氯含量

Abstract:

During the regular inspection of a 0.2 MM TPY lubricating oil hydrogenation unit in a petrochemical company, it was found that there was severe corrosion on the tube pass of the high-pressure hydrogenation heat exchanger, mainly concentrated in the lower temperature area of the lower half of the heat exchange tube. According to the analysis of corrosion products, it was mainly underdeposit corrosion caused by ammonium chloride crystallization. The analysis of the operation status of the unit showed that the main factors affecting the crystallization of ammonium chloride included the chlorine content in the feedstock, the water injection effect of the heat exchanger and the operating temperature of the heat exchanger. In the anti-corrosion upgrade and renovation of the heat exchanger, the use of specialized dechlorinating agents effectively reduced the chlorine content of the feedstock, increased the outlet temperature of the tube pass, reduced the possibility of ammonium chloride crystallization, improved the water injection flushing effect, reduced the concentration of ammonium chloride and its residence time on the heat exchange surface. The material upgrade and renovation improved the corrosion resistance of the heat exchange surface metal. During the three-year operation period after the upgrade and renovation, there was no ammonium salt crystallization on the tube pass of the heat exchanger, which prevented the underdeposit corrosion caused by ammonium salt and ensured the long-term operation of the lubricating oil hydrogenation unit.

Key words: lubricating oil hydrogenation, high pressure heat exchanger, ammonium salt crystallization, corrosion under scale, chlorine content