煤粉高掺钙燃烧时煤灰矿物形成机理的热力学分析

THERMODYNAMIC STUDY ON FORMATION MECHANISM OF COAL ASH MINERALS AT HIGH CALCIUM CONTENT IN PCC BOILERS

以热力学分析为主要手段,对煤粉在高掺钙条件下燃烧时煤灰矿物的形成机理进行了研究。研究表明,在高掺钙条件下,煤灰形成过程中的固相反应将向优先生成硅酸二钙2CaO?SiO2和钙铝黄长石2CaO?Al2O3?SiO2的方向进行,因此煤灰的矿物组成将以硅酸二钙和钙铝黄长石为主,这与以玻璃体和石英、莫来石为主的普通粉煤灰的矿物组成完全不同。硅酸二钙具有很好的水硬性,利用这一特性,可以开展进一步的研究,即通过掺钙对粉煤灰的进行改性处理,改善其矿物组成,使粉煤灰成为本身具有水硬性的类水泥材料,从而促进电厂粉煤灰的综合利用。

Through thermodynamic analysis, the formation mechanism of the coal ash minerals is studied on condition that much calcium oxide is added to the coal in the PCC（pulverized coal combustion） boilers. At high calcium content, the solid phase reactions during the process of coal ash formation are to first generate Dicalcium Silicate （2CaO.SiO2） and Gehlenite （2CaO·Al2O3·SiO2）, which will be the main minerals in coal ash This is entirely different from the common low-calcium fly ash, in which vitreous is the main mineral and quartz as well as mullite is the usual crystal. The hydranlicity of Dicalcium Silicate can be employed for the further study. That is, the mineral composition of fly ash can be improved by adding calcium to the coal. As a result, the fly ash from PCC boilers will become some kind of hydraulic material itself, and then the ash utilization can be greatly boosted.