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利用热天平对2种电站循环流化床飞灰富氧燃烧条件下碳酸化的特性进行了实验研究。重点探讨了温度和CO2浓度对CaO碳酸化速率的影响规律。发现温度是CaO碳酸化的重要影响因素。在500～800℃内,温度升高会加速碳酸化反应,包括反应速率和最终转化率。得出:富氧燃烧下循环流化床中的高温受热面,将是CaO发生碳酸化并结垢的主要部位。飞灰碳酸化的实验结果表明,高的CO2浓度是会加速CaO的碳酸化反应,得到更高的转化率。但是,这种影响随着温度的降低而减弱。飞灰孔隙特性也对CaO的碳酸化反应起很重要的作用。对CaO活化能的计算,采用了分区计算的方法。2种飞灰的活化能相差不大,而且产物层控制阶段的活化能都几乎是化学反应控制阶段的2倍。
The characteristics of carbonation under the oxy-fuel combustion conditions of circulating fluidized bed fly ash of two kinds of power plants were experimentally studied by thermobalance. The effects of temperature and CO2 concentration on the carbonation rate of CaO are discussed. It is found that temperature is an important factor of CaO carbonation. In 500 ~ 800 ℃, the temperature will accelerate the carbonation reaction, including the reaction rate and the final conversion rate. It is concluded that the high temperature heating surface in circulating fluidized bed under oxygen-rich combustion will be the main site for carbonation and scaling of CaO. Experimental results of carbonation of fly ash show that high CO2 concentration accelerates the carbonation of CaO and leads to higher conversion. However, this effect diminishes as the temperature decreases. Fly ash pore properties also play an important role in the carbonation of CaO. Calculate the activation energy of CaO, using the method of partition calculation. The activation energies of the two kinds of fly ash are almost the same, and the activation energy of the control layer of the product layer is almost twice that of the chemical reaction control phase.