常减压装置塔顶低温腐蚀评估中的相关计算

Calculation Related to Overhead Corrosion Evaluation of Crude Distillation Unit

常减压装置塔顶系统的腐蚀是一个影响炼油装置安全长周期运行的突出问题,然而由于其发生在局部,并且腐蚀过程复杂,影响因素众多,无论是实际测量还是模拟环境试验都存在一定困难,因此塔顶腐蚀的监控一直没有很好解决。针对塔顶系统的HCl露点腐蚀和铵盐结晶建立了相应的理论计算模型,可基于炼厂现有数据计算塔顶水露点、理论注水量及氯化铵结晶温度等参数。利用计算结果能够方便地确定塔顶腐蚀风险部位及程度,为炼油企业工艺防腐蚀操作提供科学指导。

The corrosion of the overhead system of crude distillation unit(CDU) is one of the most serious threats to the safe long-term operation of the refinery. However, due to its local occurrence,complicated process and a considerable amount of influencing factors, there were difficulties in measurements in field or simulation experiments in the laboratory. As a result, the monitoring and control of the overhead corrosion have not been solved well so far.In this paper,the corresponding theoretical models were established for two main corrosion mechanisms of the overhead system, i. e.,the HCl dew point corrosion and the ammonium chloride fouling. Using these models,parameters such as the aqueous dew point, water injection rate and ammonium chloride formation temperature can be calculated according to the existing refinery data. The calculation results can be used to assess the overhead corrosion risk and to provide guidance for the anti-corrosion operation of the refinery.