The GGH material in the boiler flue gas system is ND steel heat pipes, which suffer severe corrosion in low-temperature, humid flue gas
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The image below shows the heat pipes used in a GGH within wet flue gas at low temperatures (60–90°C) in a certain boiler; they were discarded after less than a year of use. ND steel and 09CrCuSb steel are recommended materials for coal-fired boilers, flue pipes, chimneys, boiler air preheaters, and economizers. However, its service life is short due to corrosion in such an environment, which limits the use of GGH. How to address surface corrosion of heat pipes is crucial for enabling GGH to function in flue gas; what methods are the best to use?
In low-temperature and humid flue gas environments, 09CrCuSb (ND steel) is sensitive to acidic gases such as SO2 and H2S, making it prone to corrosion. To address this issue, the following methods can be considered: 1. Surface treatment techniques: Using high-performance anti-corrosion coatings, such as epoxy resin coatings or polyurethane coatings, can effectively prevent direct contact between the steel and corrosive gases. 2. Choose more corrosion-resistant materials: Use stainless steel or special alloy steels (such as titanium-containing alloys) in place of traditional ND steel, as these materials have better corrosion resistance. 3. Use desiccants or desulfurization equipment: Remove moisture by adding desiccants to the flue gas, or eliminate acidic components using desulfurization devices, thereby reducing corrosivity. 4. Change working environment conditions: Increase the temperature in the flue gas and reduce the duration of periods at low temperatures, thereby minimizing condensation and corrosion issues in cold conditions. Adopting one or more of the above measures can effectively extend the service life of GGH heat pipes and ensure their proper operation in flue gas systems. .