常压塔顶回流系统多相腐蚀流的分布规律及露点腐蚀特性预测

Distribution Rule of Multiphase Corrosion Flow and Prediction of Dew Point Top Corrosion Characteristics in Return Flow System of Atmospheric Pressure Tower Top

针对某炼化企业常压塔顶回流系统,采用AspenPlus软件构建了多组分流体相态-离子平衡模型,获得了塔顶挥发管线内腐蚀性介质HCl、H_(2)S的气液平衡分布情况,实现了塔顶管道内腐蚀流体分布量化特性预测。结果表明:随着温度的降低,水相中组分HCl、H_(2)S的摩尔流量显著增加,通过初始溶解温度确定露点温度为101.2℃,露点处pH最低可达2.59,露点腐蚀发生在塔顶出口管线附近;塔顶出口管道有3个液膜覆盖率较高的区域,分别是挥发管线入口垂直管壁、弯头内壁和水平管下壁,在露点处大部分HCl气体溶解在冷凝水汇聚成的初始液膜中,因此初始液膜汇聚的区域就是腐蚀频发的区域。

Aiming at the return flow system of atmospheric pressure tower top in a refining and chemical enterprise,a multicomponent fluid phase-ion equilibrium model was constructed by Aspen Plus software.The gas-liquid equilibrium distribution of corrosive media HCl and H,S in the tower top volatile pipeline was obtained,and the quantitative characteristics of corrosion flow distribution in the tower top pipeline were predicted.The results show that the mole flow rates of HCl and H,S in the aqueous phase increased significantly with the decrease of temperature.The dew point temperature was determined to be 101.2℃by the initial dissolution temperature,and the lowest pH at the dew point could reach 2.59.The dew point corrosion occurred near the outlet pipeline of the tower top.There were three areas with high liquid film coverage in the tower top outlet pipeline,which were the vertical pipe wall of volatile pipeline inlet,the inner wall of the elbow and the lower wall of the horizontal pipe.At the dew point,most of the HCl gas dissolved in the initial liquid film formed by the condensate,so the area where the initial liquid film converges was the area where corrosion occurred frequently.