煤燃烧时形态硫的析出及钙基添加剂的作用

在固定床反应器上进行了大同烟煤以及添加钙基固硫剂的样品在不同氧气浓度、不同升温速率下的燃烧实验.对所得到的SO₂逸出曲线采用Gaussian拟合，得到了各形态硫燃烧形成SO₂的温度范围以及影响形态硫逸出的反应条件.结果表明：随着升温速率增加，各形态硫燃烧释放SO₂的温度向高温区移动.氧气浓度升高，各形态硫燃烧释放SO₂的温度提前，而且它们之间的温度间隔缩小.加入的钙基添加剂中，CaO和Ca(OH)₂具有较高的固硫能力，而CaCO₃由于与SO₂反应困难，在低温阶段没有固硫效果；相反，由于它的催化作用，在低温阶段甚至促进了SO₂的释放.机械搅拌法和超声搅拌法加入的Ca (OH)₂由于高分散性，表现出比机械混合更好的固硫效果，其中超声的作用尤其明显.实验证明，固硫中间体CaSO₃在进一步燃烧形成CaSO₄的过程中会释放出一定量的SO₂.

EVOLUTION OF SULFUR FORMS AND SULFUR RETENTION EFFECTS OF CALCIUM-BASED ADDITIVES DURING COAL COMBUSTION

Combustion experiments of Datong coal and its Ca added samples were performed in a fixed bed reactor at different heating rates and different O 2 concentrations. From the peak fitting of SO 2 curve according to Gaussian function, the SO 2 formation temperatures of all kinds of sulfur forms were obtained. It was concluded that: (1) the combustion temperature of different sulfur forms was influenced by O 2 concentration and heating rate. They could evolve as SO 2 at lower temperature with increasing O 2 concentration or decreasing heating rate. (2) The added CaO and Ca(OH) 2 had better sulfur retention effect for the high reactivity. However CaCO 3 could increase SO 2 emission at a low temperature for its bad reactivity and its catalyzing effect on SO 2 formation. (3) The impregnation with stirring and ultrasonic treatment had much better sulfur retention effect than mechanical mixing for the high dispersion. (4) While oxidizing CaSO 3 to CaSO 4, a small amount of SO 2 was evolved.