为了确定天然气冷却器换热管腐蚀的原因,应用扫面电子显微镜、能谱分析仪、X射线衍射仪对某天然气处理厂天然气冷却器换热管的腐蚀形貌、腐蚀产物以及物象进行了分析,同时应用气相色谱仪、模拟试验法、平皿计数法、电化学法对天然气冷却器的工作介质进行了研究。分析和研究结果表明,天然气冷却器换热管腐蚀的主要原因是垢下腐蚀,防腐涂层不合格、缝隙以及细菌的存在进一步促进了垢下腐蚀。在同类工程建设过程中,要注意冷却器水压试验后的干燥、保护和施工过程中的清洁,循环水系统清洗时勿将污垢带入冷却器。换热管外防腐涂层质量不合格不但无法达到保护换热管防止腐蚀的目的,反而会加速局部区域的腐蚀。

In order to determine the cause of the corrosion of the heat exchange tube of the natural gas cooler of a natural gas processing plant, a Scanning Electron Microscope, an energy spectrum analyzer and an X-ray diffractometer were used to analyse the corrosion morphology, corrosion products and physical appearance of the heat exchanger tubes of the natural gas coolers. Gas chromatography was used to study the working medium of the heat exchanger tube, together with the simulation test method, the plate count method and the electrochemical method. The research results show that the corrosion of the heat exchanger tube is mainly caused by the corrosion under the scale and b y the fact thatthe corrosion protection coating is not up to standard, and the existence of crevices and bacteria further accelerated the corrosion under the scale. Therefore, during the construction of similar projects, attention should be paid to the drying and protection of the heat exchanger after the water pressure test, the cleaning during construction process and the prevention of dirt being re-introduced into the cooler while cleaning using circulating water. If the corrosion protection coatings do not meet the required standard, rather than protecting the heat exchanger tubes against corrosion, localised corrosion will accelerate instead.