Abstract:

To investigate the mechanism of deposition salts in waste incinerators on high-temperature corrosion, 20G and T91 steels were selected as research subjects for corrosion dynamics experiments. The study aimed to reveal the corrosion mechanisms under NaCl, Na₂SO₄ and 70% Na₂SO₄+30% NaCl deposition salt conditions with thermodynamic methods employed to validate the corrosion mechanisms. The results revealed that 20G steel exhibited slower corrosion rates than T91 steel in NaCl environments but faster rates in Na₂SO₄ environments. When the 70% Na₂SO₄+30% NaCl salt mixture was molten, it exerted a partially protective effect on 20G steel, whereas it significantly accelerated corrosion in T91 steel. Under NaCl environments, the corrosion rate of 20G steel followed the order: H₂S>HCl>air. However, in Na₂SO₄ and molten salt environments, the differences in corrosion rates across varying atmospheres were less pronounced. The primary corrosion products in 20G steel across NaCl, Na₂SO₄ and molten salt conditions were iron oxide films with maximum thicknesses of 300μm (NaCl), 420μm (Na₂SO₄) and 1400μm (molten salt), respectively. Notably, the oxide films in Na₂SO₄ and molten salt conditions exhibited distinct inner and outer layers. In Na₂SO₄ environments, sulfur enrichment was observed in the inner oxide layer, while in molten salt environments, migration phenomena of Fe and Mo elements occurred between the inner and outer oxide layers.

Key words: waste incinerator, molten salt corrosion, sodium chloride, sodium sulfate, electrochemical corrosion

摘要：

为探究垃圾焚烧炉中沉积盐对高温腐蚀的作用机制，选取20G和T91钢两种材料作为研究对象开展腐蚀动力学实验，进而揭示NaCl、Na₂SO₄和70%Na₂SO₄+30%NaCl三种沉积盐条件下钢的腐蚀作用机制，并采用热力学方法对腐蚀机理进行验证。结果表明，20G钢的氯化钠腐蚀速率低于T91钢，但硫酸钠腐蚀速率却高于T91钢。当70%Na₂SO₄+30%NaCl熔盐呈熔融液态时，其降低了20G钢的腐蚀速率，却显著提高了T91钢的腐蚀速率。在氯化钠工况中，20G钢在不同气氛下的腐蚀速率排序为H₂S>HCl>空气。然而，在硫酸钠工况和熔融盐工况中，不同气氛的腐蚀速率差异并不明显。20G钢在NaCl、Na₂SO₄和熔融盐工况中的腐蚀产物主体均为铁的氧化膜，各工况下氧化膜厚度峰值分别为NaCl工况300μm、Na₂SO₄工况420μm和熔融盐工况1400μm。其中，Na₂SO₄和熔融盐工况的氧化膜均分为内外两层，不同之处在于Na₂SO₄工况中的内层氧化膜存在S元素的富集带，而熔融盐工况中内外层氧化膜存在Fe元素和Mo元素的迁移现象。

关键词: 垃圾焚烧炉, 熔盐腐蚀, 氯化钠, 硫酸钠, 电化学腐蚀