O_2/CO_2循环燃烧方式下矿物元素蒸发特性的热力学研究(英文)

Thermodynamic equilibrium study of mineral elements evaporation in O_2/CO_2 recycle combustion

运用热力学平衡计算方法(F*A*C*T)对O2/CO2循环燃烧方式下矿物元素的蒸发特性进行了研究,并采用高温热天平进行了实验验证。结果表明,各矿物元素蒸发的主要形态分别是Na(K)Cl(g),FeO(g)和SiO(g),反应气氛和温度对矿物元素蒸发形态和蒸发率有明显影响。O2/CO2循环燃烧方式下矿物元素的蒸发率均小于常规空气燃烧,尤其是还原性气氛中,当温度为2 400 K时,常规空气燃烧矿物总蒸发率为9.65%,而O2/CO2循环燃烧方式矿物元素总蒸发率仅为4.46%。实验值比计算值略高,但主要趋势相同。

The facility for analysis of chemical thermodynamics （ F ＊ A ＊ C ＊ T） based on the Gibbs energy minimization principle was used to characterize the evaporation of mineral elements of coal in O2/CO2 recycle combustion. The effects of atmosphere and temperature on the speciation of mineral species were discussed. The results show that Na（K） Cl（ g）, FeO（g） and SiO（g） are dominant gaseous species of mineral elements. The dominant species of mineral elements in flue gases depend on both the combustion conditions （reducing or oxidizing） and the atmosphere. In O2/CO2 mixture combustion, the evaporation rate of mineral elements is much lower than that in air combustion, especially in reducing atmosphere. The total evaporation of mineral elements in O2/CO2 atmosphere and air combustion under reducing conditions is 4.46% and 9.65%, respectively, up to temperature of 2 400 K. The calculation values are consistent with the experiment values. The decrease of mineral elements evaporation is helpful to suppress the formation of fine particle matter and the tendency of initial ash deposition.