钠化提钒废水MVR蒸发器腐蚀失效分析

Corrosion Failure Analysis of MVR Evaporator for Wastewater of Vanadium Extraction from Sodium

针对某2205双相不锈钢材质的钠化提钒废水MVR蒸发结晶器出现腐蚀穿孔刺漏的问题,利用金相分析、X射线衍射(XRD)、电感耦合等离子体(ICP)、扫描电子显微镜(SEM)等材料测试表征技术获取MVR蒸发器材料金相组织、物相、化学成分及表面腐蚀形貌数据,分析设备出现腐蚀穿孔刺漏的原因。研究结果表明,设备运行过程中具有固-液-汽三相流特征的高温蒸汽携带含盐腐蚀性液滴、盐粒,对材料构成冲刷腐蚀环境,导致2205双相钢材料表面发生了严重的点蚀和晶间腐蚀。因此,2205双相不锈钢的耐腐蚀能力不足以支撑设备在苛刻的腐蚀环境中长期服役,不满足建造钠化提钒废水MVR蒸发器的材质要求。

In view of the problem of corrosion, perforation and leakage in a 2205 double-phase stainless steel MVR evaporator for wastewater of vanadium extraction from sodium, metallographic analysis, X-ray diffraction(XRD), inductively coupled plasma(ICP), scanning electron microscopy(SEM) were used to obtain the metallographic structure, phase,chemical composition and surface corrosion morphology data of the MVR evaporator material, and the reasons for corrosion, perforation and leakage of the equipment were analyzed. The research results show that the high-temperature steam with the characteristics of solid-liquid-vapor three-phase flow carries salt corrosive droplets and salt particles to form erosion and corrosion environment for the material during the operation of the equipment, which leads to serious pitting and intergranular corrosion on the surface of 2205 double-phase steel material. Therefore, the corrosion resistance of 2205 dual-phase stainless steel is not enough to support the long-term service of equipment in this harsh corrosive environment,and 2205 dual-phase steel does not meet the material requirements of the MVR evaporator.