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Na_2SO4是加剧高碱煤结渣的重要中间物质,硫酸钠的铝硅酸化过程会生成SO3。通过Na_2SO4-飞灰和Na_2SO4-Al_2O3-SiO2体系的高温矿物演变实验、高温SO3生成实验,并辅以热力学平衡计算,探究了不同体系中硫酸钠的铝硅酸化过程SO3生成机理。结果表明:硫酸钠通过高温铝硅酸化反应生成钠长石、钠霞石等低熔点含钠矿物,诱发低温共熔加剧结渣。同时,600～1 000℃铝硅酸化过程析出SO2和O2,固相表面的SO2和O2分压高,因此生成少量SO3气体。Na_2SO4-飞灰体系在高温下SO3生成量约为Na_2SO4-Al_2O3-SiO2体系的1.5～2倍。燃用高碱煤时锅炉水平烟道渣层中的Na_2SO4铝硅酸化,增加了烟气中SO3浓度。
Abstract：Na_2SO4 is an important intermediate substance that aggravates the slagging of high-alkali coal.SO3 is released during the aluminosilicate reaction of sodium sulfate.To clarify the generation mechanism of SO3 in the aluminosilicate process,experiments on high-temperature mineral evolution and SO3 generation of the Na_2SO4-fly ash and Na_2SO4-Al_2O3-SiO2 system were conducted and supplemented by the thermodynamic equilibrium calculation.The results showed that sodium sulfate converted into low-melting Na-containing minerals such as albite and nepheline through high-temperature aluminosilicate reaction,which induced low-temperature eutectic and aggravates slagging.Simultaneously,SO2 and O2 were precipitated during the aluminosilicate reaction process at 600～1 000℃.Partial pressure of SO2 and O2 around the surface of solid phase was high,thus a small amount of SO3 gas was generated.The amount of SO3 produced in the Na_2SO4-fly ash system at high temperature was about 1.5～2 times that of the Na_2SO4-Al_2O3-SiO2 system.The aluminosilicate reaction process of Na_2SO4 occurred in the slag layer in the horizontal flue of high-alkali coal-fired boilers,which increased the SO3 concentration in the flue gas.
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基本信息:
DOI：10.19585/j.zjdl.202106014
中图分类号:TM621.2
引用信息:
[1]李金芳,吕洪坤,谢娜,等.飞灰中硫酸钠铝硅酸化过程SO_3生成机理[J],2021,40(06):92-98.DOI:10.19585/j.zjdl.202106014.
基金信息:
杭州意能电力技术有限公司科技项目（EPRD2020-08）