常顶换热器铵盐垢下腐蚀案例分析及改进效果

Corrosion Case Analysis and Improvement Effect of Atmospheric Top Heat Exchanger Under Ammonium Salt Scale

为改善常顶换热器铵盐垢下腐蚀状态,通过对铵盐垢下腐蚀案例分析可知:铵盐结晶原因一是由于常顶油气中的NH_(4)Cl,二是由于常顶注入剂NH_(3)与油气中Cl-反应生成的NH_(4)Cl,分别在露点温度下结晶析出,从而产生铵盐垢下腐蚀。通过采取材料升级改造、脱盐工艺前端加注破乳剂、调整塔顶注水口位置、加强腐蚀在线监控等方法,可以改善腐蚀状态,减缓了常顶换热器铵盐垢下腐蚀。现场应用结果表明,改进后管板腐蚀速率由0.32 mm/a降为0.19 mm/a,连接管路腐蚀速率由0.21 mm/a降为0.12 mm/a。

In order to improve the corrosion state of the atmospheric top heat exchanger under the ammonium salt scale,through the analysis of the corrosion case under the ammonium salt scale,it could be seen that the ammonium salt crystallization was caused by the NH_(4)Cl in the overhead oil and gas,and the NH_(4)Cl generated by the reaction between the overhead injection agent NH_(3) and the Cl-in the oil and gas,which crystallized at the dew point temperature respectively,thus causing the corrosion under the ammonium salt scale.The corrosion state could be improved by upgrading materials,adding demulsifier at the front end of desalination process,adjusting the position of tower top water injection port,and strengthening online corrosion monitoring,the corrosion under the ammonium salt scale of the overhead heat exchanger was slowed down.The field application results showed that the corrosion rate of the improved tubesheet was reduced from 0.32 mm/a to 0.19 mm/a,and the corrosion rate of the connecting pipe was reduced from 0.21 mm/a to 0.12 mm/a.