净烟道余热回收换热管腐蚀特性研究

Study on corrosion of heat exchange tube for net flue waste heat recovery

烟道余热回收换热管在酸气作用下易腐蚀渗漏,研究其腐蚀规律对制定防腐策略有重要意义。通过挂片腐蚀试验装置,分析了烟气相对湿度、烟气温度、二氧化硫含量、积灰量、氧气含量对换热管腐蚀速率的影响规律。结果表明:随着烟气湿度的增加,换热管腐蚀速率先快速升高后趋于平缓,降低烟气相对湿度可抑制换热管腐蚀;烟气温度控制在50℃以下或80℃~100℃时换热管腐蚀程度较低,70℃为换热管腐蚀最严重的工况;脱硫效率影响换热管的腐蚀状态,降低烟气二氧化硫含量可有效抑制腐蚀;随积灰量的增加,换热管腐蚀速率先升高后降低,提高烟气流速、定期清理净烟道积灰均可有效抑制积灰腐蚀;随氧气含量升高,换热管腐蚀速率先升高后降低,氧气体积分数为8%时,氧化膜抑制作用最强。

The smoke waste heat recovery heat exchange tube is prone to corrosion and leakage under the action of acid gas.Studying its corrosion law is of great significance for formulating anti-corrosion strategies.The influence of changes in flue gas relative humidity,temperature,sulfur dioxide content,ash accumulation and oxygen content on the corrosion rate of heat exchange tube was analyzed using a hanging plate corrosion test device.The results showed that with the increase of flue gas humidity,the corrosion rate of heat exchange tube first increased and then tended to become flat.Reducing the relative humidity of flue gas could suppress the corrosion of heat exchange tube.The flue gas temperature should be controlled below 50℃,and the corrosion degree of heat exchange tube was low when the temperature was between 80℃and 100℃.70℃was the working condition with the most severe corrosion of heat exchange tube.The desulfurization efficiency affected the corrosion status of heat exchange tube,and reducing sulfur dioxide content in flue gas could effectively suppress the corrosion.As the amount of ash accumulation increased,the corrosion rate of heat exchange tube first increased and then decreased.Increasing the flue gas flow rate and regularly cleaning the ash accumulation in the flue could effectively suppress the corrosion of ash accumulation.As the oxygen content increased,the corrosion rate of heat exchange tube first increased and then decreased,and the inhibition effect of the oxide film was strongest when the oxygen volume fraction was 8%.