电站燃油锅炉腐蚀抑制剂的合成及作用机理

Synthesis and mechanism of corrosion inhibitors for power station oil- fired boilers

摘要:

以硬脂酸、软脂酸、油酸、环烷酸4种有机酸和活性MgO为主要原料，设计合成复合无机-有机酸镁腐蚀抑制剂，考察使用性能，并对其作用机理进行探究。结果表明：复合碳酸镁-环烷酸镁腐蚀抑制剂具有较好的效果，加量为1000 μg/g时，烟气中SO3含量降低了70.0%，钢片腐蚀速率降低了21.6%。进一步分析表明，合成的产品是一种纳米级MgCO3粒子在有机酸镁胶束包裹下形成的稳定胶体体系，有效解决了MgCO3粒子在燃油中分散性差的问题，有利于发挥无机-有机镁盐的协同作用。随着燃油燃烧，腐蚀抑制剂产生的MgO与燃油产生的V2O5结合，降低了V2O5的浓度，减弱了其对SO2向SO3转化的催化作用，使烟气中SO3含量降低，抑制了低温腐蚀。同时，MgO的存在使燃烧生成的钒酸盐种类由低熔点变为高熔点，高温腐蚀得到缓解。

Abstract:

Composite inorganic-organic acid magnesium corrosion inhibitor was designed and synthesized with stearic acid, palmitic acid, oleic acid, naphthenic acid, and active magnesium oxide as the main raw materials. The application performance and mechanism were tested. The results show that the composite magnesium carbonate-magnesium naphthenate corrosion inhibitor has a good corrosion inhibition effect. When the dosage is 1000 μg/g, the sulfur trioxide content in flue gas is reduced by 70.0%, and the corrosion rate of the steel sheet is reduced by 21.6%. Further analysis shows that the synthesized product is a stable colloidal system. This colloidal system was formed by nanoscale magnesium carbonate particles encapsulated by organic acid magnesium micelles. This effectively solves the problem of poor dispersion of magnesium carbonate particles in fuel and facilitates the synergistic effect of inorganic-organic magnesium salts. As the fuel burns, vanadium pentoxide, which can catalyze the conversion of sulfur dioxide to sulfur trioxide, combines with magnesium oxide produced by the decomposition of corrosion inhibitors. The concentration of vanadium pentoxide decreased, so the content of sulfur trioxide in flue gas decreased, ultimately inhibiting low-temperature corrosion. At the same time, the presence of magnesium oxide makes the type of vanadate generated by combustion change from low melting point to a high melting point, which alleviates high-temperature corrosion.