Abstract:

After the start of an alkylation unit in a petrochemical company, there was a water hammer in the condensate recovery section, resulting in corrosion and perforation of the high-pressure condensate pipelines, which affected the operation of the unit. This paper analyzes the causes of water hammer and corrosion in condensate pipelines. The corrosion causes of condensate pipelines are the superposition of bubble collapse impact and two-phase flow erosion corrosion. Water hammer and corrosion are eliminated through operation adjustment and technical transformation, and improvement measures for the steam condensate recovery section are proposed: a wall attached valve and a pressure gauge are installed before entering the flash tank; a separate condensate pipe is laid for the reboiler of the dearomatic tower, two strands of 2.2 MPa condensate are merged in front of the flash tank instead of the pipe gallery, and valves and pressure gauges are installed at the ends respectively; a separate condensate pipeline is laid for the reboiler of the light hydrocarbon removal tower, and two strands of 0.45 MPa condensate are merged in front of the discharge tank instead of the pipe gallery, valves and pressure gauges are installed at the ends respectively.

Key words: alkylation unit, condensate pipeline, bubble collapse impact, gas-liquid two-phase flow, cavitation corrosion, erosion corrosion, rapid decompression, temperature difference control

摘要：

某石化公司烷基化装置开工后蒸汽凝结水回收工段存在水击、高压凝结水管道腐蚀穿孔的现象，影响了装置运行。分析凝结水管道水击以及腐蚀原因为气泡溃灭冲击与两相流冲刷腐蚀叠加。通过操作调整与技术改造，消除了水击与腐蚀，并提出了蒸汽凝结水回收工段的改进措施：在进闪蒸罐前设置贴壁阀与压力表；脱芳烃塔再沸器敷设单独凝结水管道，两股2.2 MPa凝结水由管廊汇合改为闪蒸罐前汇合，并在末端各自设置了阀门与压力表；脱轻烃塔再沸器敷设单独凝结水管道，两股0.45 MPa凝结水由管廊汇合改为排放罐前汇合，并在末端各自设置阀门与压力表。

关键词: 烷基化装置, 凝结水管道, 气泡溃灭冲击, 气液两相流, 空泡腐蚀, 冲刷腐蚀, 快速减压, 温差控制