Corrosion Analysis and Countermeasures of Gas Boiler Flue Gas Heat Exchanger

随着绿色低碳、节能环保工作深入开展，锅炉烟气余热回收换热器应用日趋广泛，在锅炉热效率大幅提升同时，由于排烟温度持续降低，暴露出的泄漏、腐蚀等问题日益突出。本文通过对某石化企业热电装置一台新建锅炉烟气换热器泄漏的成因分析，确定泄漏原因为应力腐蚀。根据应力腐蚀三大必要条件，结合实际运行数据和锅炉结构特点等逐层剖析，发现该烟气换热器实际入口水温低于设计10℃，出口烟气温度低于设计28℃，换热管壁面温度低于H2SO4、HCl等露点温度。提出该烟气换热器实际运行环境与初始设计条件发生较大偏离是造成应力腐蚀的根本原因，并提出应对措施。有助于提高锅炉的运行效率和安全性，对同类型锅炉的运行和维护具有借鉴意义。With the deep development of green low-carbon and energy-saving and environmental protection work, the application of boiler flue gas waste heat recovery exchangers is becoming more and more extensive. While the thermal efficiency of the boiler is greatly improved, the problems of leakage and corrosion are increasingly exposed due to the continuous decrease of exhaust temperature In this paper, the cause of leakage of a newly built boiler flue gas heat exchanger in a certain petrochemical enterprise’s thermal power unit is analyzed, and it determined that the cause of leakage is stress corrosion. According to the three necessary conditions of stress corrosion, combined with the actual operation data and the characteristics of the boiler structure, it is layer by layer, and it is found that the actual inlet water temperature of the flue gas heat exchanger is 10℃ lower than the design temperature, the outlet gas temperature is 28℃ lower than the design temperature, and the wall surface temperature of the heat exchange tube is lower than the dew point temperature of H2SO4 and HCl. It is proposed that the actual operation environment of the flue gas heat exchanger deviates greatly from the initial design conditions, which is the fundamental reason for stress corrosion, and corresponding measures are proposed. It helps improve the operational efficiency and safety of boilers and serves as a reference for the operation and maintenance of similar types of boilers.