煤粉预热燃烧中硫元素转化特性实验

Experimental research on sulfur conversion characteristics of pulverized coal preheating combustion

为了控制燃煤硫排放,进行煤粉预热燃烧实验并取样分析,利用气相色谱仪、气体分析仪、X射线光电子能谱等仪器,研究煤预热、燃烧阶段硫元素的转化特性。结果表明:神木烟煤中存在黄铁矿、噻吩、亚砜、砜、磺酸盐和硫酸盐6种固态硫;经过预热过程后,煤粉中硫元素的40.5%仍以6种固态硫的形式存在于半焦中,59.5%转化为含硫气体;与原料相比,半焦中黄铁矿、噻吩、磺酸盐和硫酸盐质量分数减小,亚砜和砜质量分数增大;在燃烧过程中的还原区,当温度达到1100℃时,固态硫发生了大量分解;在燃尽区,氧化剂的增多导致噻吩、亚砜、砜和磺酸盐快速分解产生H2S和COS;在燃尽区尾部仅剩余磺酸盐和硫酸盐2种固态硫,尾部烟气中SO2的质量浓度为209 mg/m3。

In order to control sulfur emissions from coal burning,preheating combustion experiments of pulverized coal as well as sampling and analysis were carried out.The conversion characteristics of sulfur during coal preheating combustion were studied by gas chromatograph,gas analyzer and X-ray photoelectron spectroscopy.The results show that there are six kinds of solid sulfur in Shenmu bituminous coal:pyrite,thiophene,sulfoxide,sulfone,sulfonate and sulfate.After preheating,40.5%of sulfur in pulverized coal still exists in semi-coke in the form of six kinds of solid sulfur,and 59.5%is converted to sulfur-containing gas.Compared with raw materials,the mass fractions of pyrite,thiophene,sulfonate and sulfate in semi-coke decreased,while the mass fractions of sulfoxide and sulfone increased.In the reduction zone of combustion process,when the temperature reaches 1100℃,a large amount of solid sulfur decomposes.Thiophene,sulfoxide,sulfoxide and sulfonates decompose rapidly to H2S and COS due to the increase of oxidants in the burnout zone.In the burnout zone,only sulfonate and sulfate are left,and the mass concentration of SO2 in the tail flue gas is only 209 mg/m3.