苯甲酸蒸馏塔内结构件腐蚀失效的原因及改进措施

Causes Leading to Corrosion Failure of Internal Structural Units in Distillation Tower of Phenviformic Acid and Measures for Improving the Corrosion Resistance

苯甲酸蒸馏塔内结构件腐蚀失效严重,过去对其机理、相关环境影响及选材方面的研究报道较少。通过化学、电化学、金相、电镜、能谱分析等手段,考察了苯甲酸蒸馏塔内结构件的腐蚀失效状况,对使用国产316不锈钢制造的结构件的失效原因进行了宏观、微观分析。结果表明,其腐蚀类型为晶界腐蚀和晶间型应力腐蚀,腐蚀的起因是由于碳化物和磷、硅等元素在晶界的偏析所致;另外,塔内高温、应力和混合有机酸的复合作用也加速了材料阳极的溶解过程,导致塔内结构件快速腐蚀失效。针对上述结果提出了苯甲酸生产过程中设备的选材和防腐蚀方法,以减轻乃至避免腐蚀的发生,为今后设备国产化提供科学依据。

The corrosion-induced failure of the internal structural units in the distillation tower for phenylformic acid was investigated by making use of chemical, electrochemical, metallorgraphic, scanning electron microscopic, and energy dispersive spectrometric analyses.The causes leading to corrosion failure of 316 stainless steel were analyzed at a macro and micro level.Results indicate that the corrosion failure of the internal structural units made of stainless steel is attributed to corrosion at the crystal interface and intergranular corrosion as well.The two types of corrosion were initiated by the segregation of carbides and r and Si elements at the grain boundary.At the same time, the dissolving process of the anode was accelerated by the combined effect of high temperature, stress and mixed organic acids inside the tower, leading to fast corrosion failure of the internal structural units of the tower.With a view to the above-mentioned failure features, the methods for material selection and corrosion prevention of the equipments were suggested in relation to the production of phenviformic acid.Hopefully, the present research is to effectively alleviate and even avoid corrosion, providing scientific basis for the domestic industrialization of relevant equipments.