Leakage reason of heat exchanger in natural gas purification device

A perforation leakage accident of heat exchange tube occurred in the heat exchanger of a company’s natural gas purification device during service. The causes of heat exchange tube leakage were analyzed by means of macroscopic observation, chemical composition analysis, metallographic examination, scanning electron microscopy and energy spectrum analysis. The results show that the main reason for the leakage of the heat exchange tube was that the solid particles in the shell side medium were attached to the outer surface of the heat exchange tube due to the slow flow rate of the medium. With the continuous thickening of the scale layer, the water gas containing H₂S, CO₂ and other acidic substances penetrated into the scale layer, forming a closed cell corrosion environment, and the pH of the local area decreased, which caused the corrosion thinning of the wall thickness of the heat exchange tube from the outer surface to the inner surface, and finally led to the perforation and leakage of the heat exchange tube.