垃圾焚烧炉水冷壁材料20G钢在硫氯气氛下的腐蚀特性

Corrosion characterization of waste incinerator water-cooled wall material 20G steel under sulfur-chlorine atmosphere

  • 摘要: 受热面高温腐蚀泄露严重威胁垃圾焚烧炉安全运行,腐蚀性元素S和Cl在其中发挥着重要作用,但H2S和HCl在与合金及氧化膜反应中呈现着不同的理化特性和腐蚀特征。由此,进行了气相腐蚀动力学实验,对比了不同温度、浓度气氛下高温H2S腐蚀和HCl腐蚀的速率差异,并基于Pilling-Bedworth理论对腐蚀深度模型进行优化,优化后的模型可以对不同气氛下的腐蚀深度进行预测,进而在一定程度上用于垃圾焚烧炉管壁材料的生命周期计算。气相动力学实验结果表明:在450 ℃和550 ℃下,H2S的腐蚀速率大于HCl。而在650 ℃下,虽然反应刚开始H2S腐蚀速率较大,但72 h后,HCl腐蚀速率开始大于H2S腐蚀速率。H2S和HCl腐蚀速率与温度呈现正相关性,温度越高,腐蚀速率越大。H2S腐蚀反应的平均活化能为22.8 kJ/mol,低于HCl腐蚀反应的平均活化能(52.0 kJ/mol),但HCl腐蚀反应对温度更敏感,随着温度升高,HCl腐蚀速率增加幅度明显快于H2S。H2S腐蚀速率与浓度呈现正相关性,H2S浓度越大,腐蚀越快,但HCl腐蚀速率与浓度没有显著相关性。此外,氧气对于H2S、HCl的腐蚀速率存在协同作用。氧气存在情况下,H2S和HCl的腐蚀速率与无氧气情况相比明显变大,腐蚀速率增幅平均为52.5%。腐蚀产物的表征分析发现H2S和HCl主要通过点蚀的方式渗透进入铁基体,样品表面主要成分为铁的氧化物,H2S和HCl腐蚀产物分别为FeS和FeClx

     

    Abstract: High temperature corrosion poses a threat for waste incinerators operation, in which corrosive elements S and Cl play an important role in the corrosion process. The H2S and HCl present different physicochemical properties and corrosion characteristics in the reaction with alloys and oxide films. For this end, gas-phase corrosion kinetics experiments were carried out to compare the rate difference between high-temperature H2S corrosion and HCl corrosion, and the corrosion depth model was optimized based on the Pilling-Bedworth theory, which can predict the corrosion depth under different atmospheres. In turn, it can be used to some extent for life cycle calculations of waste incinerator pipe wall materials. The results showed that the corrosion rate of H2S was greater than that of HCl at 450 ℃ and 550 ℃. And the corrosion rate of H2S was greater at the beginning of the reaction at 650 ℃, while the corrosion rate of HCl reversed to exceed the corrosion rate of H2S after 72 h. The corrosion rates of H2S and HCl showed a positive correlation with temperatures. Although the average activation energy of the H2S corrosion reaction was 22.8 kJ/mol, lower than the average activation energy of HCl corrosion reaction 52.0 kJ/mol, the HCl corrosion reaction was more sensitive to the temperature. Thus, as the temperature rose, the corrosion rate of HCl increased significantly faster than the H2S. H2S corrosion rate and concentration showed a positive correlation while HCl corrosion rate showed no positive correlation with HCl concentration. Moreover, oxygen has a synergistic effect on the corrosion rate of H2S and HCl. In the presence of oxygen, the corrosion rate of H2S and HCl was significantly accelerated compared with the absence of oxygen, and the corrosion rate increase was 52.5% on average. H2S and HCl mainly penetrated into the iron matrix by pitting corrosion, resulting in the main component of the sample surface was iron oxide, and the corrosion products of H2S and HCl was FeS and FeClx, respectively.

     

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