常减压蒸馏装置塔顶空冷器腐蚀泄漏研究

Study on Corrosion Leakage of Atmospheric Tower Overhead Air Coolers

对中国石化青岛炼油化工有限责任公司常减压蒸馏装置常压塔顶空冷A-101A发生泄漏的管束进行了失效分析,并结合泄漏发生期间工艺操作情况、采样分析数据和常顶系统历史情况对泄漏的原因进行了分析。原油中的有机氯无法通过电脱盐去除,而Cl^-对常顶双相钢空冷器的腐蚀起决定作用。实验显示2205双相钢在HCl溶液中不能形成完整的保护膜,耐蚀性差,其腐蚀速率达33.66 mm/a。该文就腐蚀原因提出了防腐蚀建议:估算露点和氯化铵结盐温度预测腐蚀部位;改变注水方式,进行间歇性大量注水;注意控制塔顶注水水质,降低Cl^-含量;控制常顶回流水pH值在6.5~7.5,如回流水pH值高于8,则应减少中和缓蚀剂注入量,降低结盐风险。

The air cooler A - 101A in atmospheric tower overhead system leaked in SINOPEC Qingdao Refining ＆ Chemical Co. , Ltd. The failure analysis has been carried out on the leaking air cooling tube bundle, and the leaking causes of have been studied based upon the operating conditions in leaking period, sample testing data and history data of atmospheric tower overhead system. The organic chlorides in crude, which could not be completely removed, played an important role in the corrosion of duplex steel. The experiments showed that the 2205 duplex steel was poor in corrosion resistance because integrated protective films couldn＇ t be formed in HC1 solution. The corrosion rate even reached 33.66 mm/a. The following effective corrosion protection measures were recommended such as ： calculating the dew point and ammonium chloride salt deposition temperature to forecast the corrosion location; changing the way of water injection to abundant intermittent water injection and lowing the C1- content; controlling pH in the range of 6.5 to 7.5. When pH of return water was higher than 8, the injection of neutralization and corrosion inhibitors should be reduced so as to minimize the salt deposition risks.