Unscheduled shutdown often occurs in diesel hydrogenation unit due to the corrosion leakage of heat exchanger. After a series of analyses of technological and flow processes, failure causes of the U-tube heat exchanger were investigated. The inside and outside mediums of heat exchanger tubes were hot high-pressure separation (HHPS) gas and cold low-pressure separation oil, respectively. A detailed examination shows that the corrosion occurs in shell side and was caused by under-deposit corrosion of NH₄Cl. Through the numerical simulation, it is found that the leakage location is at the place where water tends to accumulate. Thus, in order to prevent the corrosion of heat exchanger, the water content carried in the cold low-pressure separation oil should be reduced.

由于热交换器的腐蚀泄漏，柴油加氢装置中经常发生计划外停机。经过一系列的工艺和流程分析，研究了U型管换热器的故障原因。换热管的内部和外部介质分别是高温高压分离（HHPS）气体和低温低压分离油。详细检查表明，腐蚀发生在壳侧，是由NH ₄ Cl的沉积不足腐蚀引起的。通过数值模拟，发现泄漏位置在水易于积聚的位置。因此，为了防止热交换器的腐蚀，应该降低冷的低压分离油中携带的水含量。