含氯原油加工腐蚀与防护

Corrosion of Crude Oil Containing Chlorine and Protection

介绍了原油中氯的来源，分析了氯腐蚀的特点。根据某石化公司生产流程建腐蚀流模型，从原油进厂、储存、调合后进常减压、二次加工到产品出厂进行分析，经评估需重点对常减压蒸馏装置、重整装置、加氢装置、裂解装置进行关注并采取预防性措施：第一，对原油中氯含量进行监控，调合后的原油总氯质量分数控制在30μg／g以下（参考值），对各装置原料总氯质量分数进行监测，建议分析频率1次／d；第二，通过适当工艺调整将NH4Cl结盐点控制在固定注水点之后；及时调整高压换热器和空冷前各注水点的注水量。并控制高分含硫污水NH。HS质量分数小于4％；第三，加强临时注水管理。注水的pH值控制在略偏碱性，使加氢含硫污水保持碱性（8～9为宜）；第四，停工检修期间，对反应流出物系统的不锈钢管道焊缝做100％射线探伤检测，对不锈钢材质的低点排凝、引压管、热电偶接管等做渗透检，以保证装置的平稳运行。

The sources of chlorides in crude oil are described and the chlorine corrosion characteristics are studied. Based upon the process flow of the refinery, the crude oils are analyzed from entering the plant to storage and blending before entering the atmospheric- vacuum distillation unit, down -stream processing and ex- plant. In accordance with analysis results, the following corrosion protection measures should be taken for atmospheric - vacuum distillation unit, continuous catalytic reforming unit, hydrogenation unit, catalytic cracking unit ： 1 ） The chlorine in crude is monitored to ensure that the total chlorine in the blended crudes is bellow 30 μg/g. In addition, the total chlorine in the feedstock of each process unit is monitored and analyzed one time a day. 2） The process conditions are appropriately controlled to move the NH4 Cl deposition after water injection point, and water injection rate before high - pressure heat exchangers and air coolers should be adjusted in a timely manner. The NH4HS in the sour water from HP separator should be controlled below 4%. 3 ） Water injection management should be strengthened. The pH value of injected water is controlled at a little alkaline so as to maintain the alkalinity of sour water at 8 - 9. 4） During the scheduled overhaul, 100% RT tests are performed for the welds of stainless steels. The penetration testing is conducted for stainless steel drain lines, pressure pipelines, thermoeouples ere so as to maintain a stable operation of the unit.