煤灰及各种矿物质对SO2排放特性的影响

利用TG-DTG采用低加热速率实验研究了煤阶、脱灰及煤中主要矿物质成分对煤燃烧过程中SO2排放特性的影响，并对矿物质成分的影响机理进行了讨论。结果表明，煤中硫质量分数的高低对烟气中SO2的排放有明显影响，排放水平与硫质量分数不成比例；煤中硫向SO2转化率与煤阶之间没有明显的关联；脱灰能较小程度地促进SO2的生成，抚顺煤主要矿物质成分中Na、K、Mg以及Ca等碱金属与碱土金属明显抑制SO2的排放，同时纳米级的TiO2也减少烟气中SO2体积分数，这些成分对SO2抑制作用的顺序为MgNa≈K>Ca>Mg>Ti的次序加速焦炭的氧化；Si和Al属于惰性成分，对煤中硫的迁徙以及煤的燃烧特性没有显著影响。

Effects of coal rank, demineralization and inherent mineral species on SO2 emission in coal combustion process

It has been clarified that SO2 emission during coal combustion is the main source of acid rain， and the level of SO2 in flue gas determines the erodibility of equipments. Sulfur emission form coal during combustion is determined by fuel properties and combustion conditions. The reaction mechanism of fuel sulfur conversion to oxide and the influence of different factors are still remained unclear. In this paper， combustion of six coals with carbon contents of 77％～93% (daf) and the corresponding demineralized samples has been studied in a thermogravimetric analyzer with heating rate of 20 ℃/min to examine the effect of coal rank， demineralization and inherent mineral species on SO2 emissions. For Fushun coal demineralized by HCl， Si is the main remaining mineral species with content of 3.4% (db)， so the effect of Si on devolatilization can be examined. AlCl3， Fe(C5H5)， Ca(OH)2， KOH， MgCl2， NaOH and TiO2 were used as the catalyst precursors. The results show that the concentration of SO2 in flue gas is associated with the sulfur content in coal， whereas there is no clear relation between them. That demineralization increases the SO2 emission， which indicates that inherent mineral species play a major role during combustion. Si， Al， Mg， Na， K， Ca， Fe and Ti， which are the main species in the ash of Fushun coal， are added into the demineralized coal sample by suitable method with different catalysts precursors. In the minerals， some species decrease the SO2 emission with the sequence of MgNa≈K>Ca>Mg>Ti. Si and Al are found to be inert during coal combustion. The mechanism of influence of different catalysts on the combustion is also discussed.