加氢装置高压空冷器制造质量分析与改进措施

Manufacturing quality analysis and improvement measures of high pressure air cooler in hydrogenation unit

高压空冷器是石化企业加氢装置的关键设备,近年来,在开工和运行过程中多次发生泄漏问题,严重影响企业生产安全和经济效益。选取国内两家炼化企业的加氢装置碳钢高压空冷器,对管接头进行金相组织分析和显微硬度测试。结果显示,焊缝区存在魏氏组织,硬度最高达到250 HV10;管板侧热影响区中还存在马氏体组织,硬度最高超过330 HV10。原因为制造过程中焊后热处理不充分甚至未进行焊后热处理。结合高压空冷器恶劣的服役工况,存在较高的湿H;S应力腐蚀开裂风险,针对碳钢高压空冷器管接头的制造现状,提出了正确测量焊接接头的显微硬度、进行有效的焊后热处理、加强过程管控等改进措施。

High pressure air cooler is the key equipment of hydrogenation unit in petrochemical enterprises. In recent years, leakage problems have occurred many times during start-up and operation, seriously affecting the production safety and economic benefits of enterprises. The carbon steel high pressure air cooler of hydrogenation unit in two domestic refining and chemical enterprises is selected to analyze the metallographic structure and microhardness of the pipe joint. The results show that there is widmanstatten structure in the fillet welds, and the highest hardness is about 250 HV10. For the heat affected zones on the tubesheet side, there is martensite structure and the highest hardness even exceeds 330 HV10. This is mainly due to insufficient or even no postweld heat treatment in the manufacturing process. Combined with the harsh service condition of high pressure air cooler, there is a high risk of wet H;S stress corrosion cracking. In view of the manufacturing status of carbon steel high pressure air cooler pipe joints, the improvement measures such as correct measurement of microhardness of welded joints, effective postweld heat treatment and strengthening process control are put forward.