柴油加氢装置关键换热器管束腐蚀机理研究

摘要

Object To make clear the cause of corrosion failure of refinery heat exchanger tubes (15CrMo steel and 321 stainless steel) for diesel hydrogenation unit of Lanzhou Petrochemical Company.Methods High-temperature autoclave was used to test and simulate the corrosion mechanism of 15CrMo and 321 stainless steel in corrosion medium.Results The failure form of 15CrMo steel exhibited quick uniform corrosion under ammonium salt scale and pitting corrosion for others. On the contrary, the main failure form of 321 stainless steel showed pitting under ammonium salt scale.Conclu-sion To avoid corrosion perforation caused by ammonium salt crystallization, it is suggested to improve the outlet tem-perature of the heat exchanger to 230℃ above, change the water injection technology for the outlet of the heat exchanger to note neutralization corrosion inhibitor, and supply a dechlorination can at the outlet of the hydrogenation reactor.%目的 明确兰州石化柴油加氢装置某换热器管束(主要材质为15CrMo钢和321不锈钢)的腐蚀失效原因.方法 采用高温高压釜试验和模拟铵盐结晶试验研究15CrMo钢和321不锈钢在服役介质中的腐蚀机理.结果 15CrMo钢的腐蚀失效形式表现为铵盐结晶下的快速均匀腐蚀和其他部位的点蚀;而321不锈钢的腐蚀失效形式则相反,主要表现为铵盐结晶下的点蚀.结论 为避免铵盐结晶引起的腐蚀穿孔,建议提高换热器出口温度到230℃以上,将换热器出口的注水工艺改为注中和缓蚀剂,在加氢反应器出口增设脱氯罐.