催化余热锅炉低温省煤器炉管弯头泄漏失效分析

Failure Analysis on the Leakage of Tube Elbow for Catalytic Low Temperature Economizer

催化装置余热锅炉(简称余锅)为利用再生烟气的余热,向装置汽轮机及生产工艺提供所需蒸汽的设备。低温省煤器位于余热锅炉的低温段。由于烟气中S、水蒸气和粉尘的作用,低温省煤器炉管容易发生腐蚀失效。文章通过对低温省煤器进行宏观检查,测厚,化学成分分析,金相组织检验,低温省煤器进、出口温度以及露点温度计算等,确定其炉管弯头泄漏失效的主要原因是硫酸露点腐蚀,并对此给出材质升级、炉墙密闭、提高进水温度等建议。

Waste heat boiler of the catalytic unit(boiler for short)provides the equipment for the steam turbine and the production process using the waste heat of the regenerated flue gas.The low temperature economizer is located at the low temperature section of the waste heat boiler.Due to the effects of sulphur,water vapour and dust in the flue gas,the furnace tube of low temperature economizer is liable to corrosion failure.Through macroscopic examination,thickness measurement,chemical composition analysis,metallographic examination,and calculation of low temperature economizer inlet,outlet temperature and dew point temperature,it is made certain that the main reason for the leakage failure of furnace tube elbow is the sulfuric acid dew point corrosion.Aiming at this,the paper brings forward such suggestions as material upgrading,furnace wall sealing and raising the inlet water temperature.