富氧燃烧工艺的烟气中富含CO2,同时SOx浓度也有一定变化。研究了不同煤种飞灰在富氧燃烧烟气中的固硫机理。在高温沉降炉中,测试了6种典型煤粉飞灰在空气燃烧烟气和富氧燃烧烟气中的固硫过程,分析了影响因素。结果表明:烟煤灰样固硫量很少,与烟煤灰中缺少碱土金属(Ca、Mg)有关;褐煤飞灰固硫现象显著。褐煤灰在空气燃烧下的固硫率为43%,在富氧燃烧条件下灰固硫率提高至60%。在富氧气氛下,1000℃灰固硫速率明显高于800℃;飞灰固硫的温度窗口及反应效果与SO2氧化生成SO3的反应一致。灰中部分碱土金属会与Si、Al等结合,这部分碱土金属不具备固硫活性。SO3生成与灰中Fe2O3催化、碱土金属固硫有关。发展富氧燃烧与Ca基干法脱硫的协同技术,对于实现炉内烟气的深度SOx减排有应用价值。

During the oxy-fuel combustion, rich CO2 is produced in flue gas with varied SOx concentration. In this paper, the characteris⁃tics of sulfur retention in fly ash from different coal in oxy-fuel combustion was studied. The SOx absorption in fly ashes of six coals wastested on the high-temperature drop-tube furnace, in which the flue gas atmosphere set for oxy-fuel or air burning. The influencing fac⁃tors were analyzed. The results show that the sulfur retention amount is very low in bituminous coal ash, which is related to the lack of al⁃kaline earth metal (Ca, Mg) in bituminous coal ash. However, the sulfur retention of lignite ash is significant. The fixed sulfur efficiencyis about 43% for lignite ash after air-firing, as compared with 60% after its oxy-fuel combustion. The sulfur absorption rate is much high⁃er in oxy-fuel flue gas in 1 000 ℃ rather than in 800 ℃ . The temperature window and reaction effect of fly ash sulfur fixation are consist⁃ent with the reaction of SO2 oxidation to SO3. Some alkaline earth metals have combined with Si or Al, etc., and these alkaline earth met⁃als do not have sulfur fixation activity. SO3 formation is effected by both catalytic effect of Fe2O3 and the sulfur-retention behavior in ash.Through both oxy-fuel combustion and dry scrubbing of Ca sorbent added together, it is promising to control SOx emission deeply in furnace.

0 引言

1 试验

2 试验结果及分析

   2.1 SO2体积分数与温度对飞灰固硫的影响

   2.2 富氧燃烧气氛下的飞灰固硫率

   2.3 碱土金属（Ca、Mg）含量的影响

   2.4 碱金属（Na、K）含量的影响

   2.5 灰中Si、Al组成的影响

   2.6 灰中Fe2O3的影响

3 应用分析

4 结论