乙二醇装置T530零效蒸发器损伤分析和控制措施

Rupture Analysis of T530 Zero-order Evaporator of Ethanediol Plant and Its Control Measures

对乙二醇装置零效蒸发器内壁开裂状况、性质和原因加以探讨。结果表明，裂纹基本属于弱氧化性介质条件下的晶间腐蚀开裂；介质中含有一定量的乙酸（CH3COOH）和少量甲酸（HCOOH），塔体材料抗晶间腐蚀性能不足，不适当的焊接工艺导致部分热影响区较长时间处于敏化温度（450-850℃）范围是引发塔体开裂的主要因素。防治途径包括：采用超低碳C≤0．02％、含有一定量Mo（2％～4％）或一定量艿铁素体（3％～10％）的奥氏体不锈钢制作壳体；严格执行小热输入、小摆动、窄焊道、低层间温度的焊接工艺；严格控制介质中杂质含量及pH值。

Situation,character and reason of innerwall cracks of zero - order evaporator were studied . The results showed that above cracks are intergranular corrosion cracking basically in weak oxidative medium; they are caused by following factors mainly： contain some acetic acid and little formic acid in active medium, IGCC - resistance of shell material is imuiticient, improper welding technology lead to local HAZ in the sensitized temperature range（450 ～ 850 ℃ ）for longer time. Prevention measures include ： select austenitic stainless steel with carbon content ≤ 0.02 Wt %, molybdenum content 2 ～4 Wt % or δ errite content 3 ～10 structure % ; use small heat input, little swing, narrow bead and low interpass temperature during welding process; control strictly impurity content and pH value of medium.