煤燃烧脱硫过程中影响无机矿物转化行为的因素

以合山煤(HS)和万盛煤(WS)为研究对象,分别讨论了当石灰石作固硫剂时钙硫比、温度等因素对固硫效率的影响;运用XRD测试手段,研究了不同脱硫条件对其灰渣产物矿相组成的影响规律,并利用CaO-Al₂O₃-SiO₂三元相图进行分析,从而初步揭示出煤燃烧脱硫过程中无机矿物质间的转化行为.实验表明:燃烧温度和钙硫比对固硫率及灰渣产物的矿相组成都具有很重要的影响.升高温度或提高Ca/S,能明显促进CaO与煤粉中无机成分间的固相反应,利于C₄AF、C₂AS、β-C₂S等矿物的形成,但大于1050℃后易使硬石膏发生分解,而引起固硫率下降.固硫产物中含硫矿物的形式与含量决定了不同温度下固硫效率.本实验中,石灰石对合山煤的最佳固硫条件为Ca/S＝2～3,t=850～900℃,此时固硫率高达90%左右.

Factors of Effects on Transformation Behaviors of Inorganic Mineral Matters in Desulfurizing Process of Burning Coal

The Heshan coal and the Wansheng coal were selected to investigate the effects of Ca/S molar ratio, combustion temperature and other factors on the desulfurization efficiency when limestone as a desulfurizer. And then the possible effects of various desufurizing systems on the mineral constituents of their residues were discussed by using the X-ray diffraction analyzer. Moreover, the phase diagrams of the ternary system CaO-Al2O3-SiO2 were further used in order to find out the transformation behaviors of inorganic mineral matters in the desulfurizing processes of burning coal on the basis of the XRD results. The results show that the combustion temperature and the Ca/S molar ratio are the key factors affected the desulfurization efficiency and their residues' mineral constituents. When the temperature raised and the Ca/S ratio increased, the solid-phase reactions between CaO and some inorganic matters in coal ash will be obviously accelerated, which thus are good for the formaion of many mineral matters such as C4AF,C2AS and beta-C2S. Yet the anhydrite formed will decompose if the temperature is above 1050 degrees C and then the desulfurization efficiency will decrease. The desulfurization efficiency in different temperature is mainly decided by the existence form of the sulfur-contained mineral matters and their contents in the residue. In the experiment, the best desulfurization efficiency for the HS coal was about 90% when the Ca/S ratio was 2 or 3 and the range of the temperature was from 850 degrees C to 950 degrees C.