H型翅片管换热器烟气低温腐蚀影响因素实验研究  

Experimental Study on the Influencing Factors of Low Temperature Corrosion of H-Type Finned Tube Heat Exchangers

作　　者：裴勇[1] 何雅玲[1] 

机构地区：[1]西安交通大学热流科学与工程教育部重点实验室,西安710049

出　　处：《西安交通大学学报》2017年第3期54-61,共8页Journal of Xi'an Jiaotong University

基　　金：国家重点基础研究发展计划资助项目(2013CB228304)

摘　　要：为研究换热器的低温腐蚀,搭建了换热器烟气低温腐蚀实验台。实验台可模拟烟气环境并实现多种因素的定量控制。以工业余热回收中常用的H型翅片管为对象,进行了H型翅片管换热器烟气低温腐蚀影响因素的实验研究。观察并分析了H型翅片管在不同壁面温度下的表面形貌变化以及腐蚀产物,得到了不同烟气流量、烟气温度、烟气酸体积分数以及壁面温度对应的酸沉积速率。结果表明:壁面温度低于水蒸气露点时腐蚀较为严重,腐蚀机理为吸氧腐蚀;烟气流量、烟气温度、烟气酸体积分数以及壁面温度对酸沉积速率均有不同程度的影响;随着烟气酸体积分数从10×10^(-6)增加到50×10^(-6),酸沉积速率从2.50×10^(-7) mol·m^(-2)·s^(-1)近似线性增加到7.03×10^(-7) mol·m^(-2)·s^(-1);随着壁面温度从80℃降低到50℃,酸沉积速率从3.06×10^(-7) mol·m^(-2)·s^(-1)增大到1.75×10^(-6) mol·m^(-2)·s^(-1),当壁面温度继续降低时,沉积的酸一部分被冷凝水带走,导致测得的酸沉积速率减小;酸雾的生成和黏附对酸沉积速率有较大的影响。研究结果对开发抗低温腐蚀技术、改善烟气余热利用系统提供了实验基础。An experimental rig was constructed for the study of low temperature corrosion of heat exchangers. The experimental rig can simulate flue gas environment and control multiple factors quantitatively. H-type finned tube heat exchangers widely used in waste heat utilization was used for the experimental study on the influencing factors of low temperature corrosion of H-type finned tube heat exchangers. The changes of surface morphology and corrosion products of H-type finned tube heat exchangers under different tube wall temperatures were observed and analyzed, and the condensation rates of sulphuric acid under different flue gas flux rates, flue gas temperatures, sulphuric acid volume fractions and tube wall temperatures were obtained. The results showed that H-type finned tube heat exchangers are corroded relatively badly when the tube wall temperature is lower than water vapor dewpoint and the corresponding corrosion mechanism is oxygen absorption corrosion. Flue gas flux rate, flue gas temperature, flue gas sulphuric acid volume fraction and tube wall temperature can influence the condensation rate of sulphuric acid but in different degrees. As flue gas sulphuric acid volume fraction increased from 10 × 10^-6 to 50×10^-8 , the condensation rate of sulphuric acid increased almost linearly from 2.50 ×10^-7mol·m^-2·s^-1 to 7.03 × 10^-7 mol·m^-2·s^-1; as tube wall temperature decreased from 80℃ to 50 ℃, the condensation rate of sulphuric acid increased from 3.06×0^-7 mol·m^-2·s^-1 to 1.75 ×0^-6 mol·m^-2·s^-1. When tube wall temperature decreased further, the measured condensation rate of sulphuric acid decreased because of the heat dissipation of condensed water. The formation of sulphuric acid fog and it＇s adhesion to the tube wall have a great impact on the condensation rate of sulphuric acid. The research results have some guiding significance for developing novel techniques to alleviate low temperature corrosion and improving flue gas waste- heat utilization systems.

关 键 词：低温腐蚀 H型翅片管 烟气 余热利用 

分 类 号：TK172.3[动力工程及工程热物理—热能工程]