石灰石在二氧化碳与空气混合气氛下的分解动力学

A study on kinetics of limestone decomposition in air and CO_2 atmospheres

采用热重-差式扫描量热分析(TG-DSC),分别在空气气氛和81%空气-19%二氧化碳混合气氛下,对4种不同品质的石灰石进行热分解特性研究。结果表明,在空气气氛中,石灰石分解遵循相边界一维反应模型,即G(α)=α;在81%空气-19%二氧化碳气氛中,石灰石分解遵循随机成核和随后生长模型,即G(α)=-ln(1-α)。在81%空气-19%二氧化碳气氛中,较高的二氧化碳分压延迟了碳酸钙的分解,使得石灰石分解的开始温度比空气气氛中高200℃左右,分解活化能约为空气气氛的3倍,且粒径大到一定程度后活化能变小。碳酸镁的存在可以促进碳酸钙的分解。在81%空气-19%二氧化碳气氛下,适宜的石灰石粒度为小于0.105 mm,适宜的分解控制温度为890℃。

The decomposition kinetics of 4 different limestones in air and 81% air-19% CO2 atmosphere have been investi- gated respectively.Results showed that the decomposition of limestones in air followed one-dimensional phase boundary reac- tion model G （α）=α.While in 81% air-19% CO2 atmosphere ,the kinetic model of decomposition was nucleation and growth model G（α=-ln（1-α）.Under a higher CO2 partial pressure, the decomposition of limestone was delayed which led to the in- crease of initial decomposition temperature by 200 ℃ and the increase of activation energy by three times.Furthermore ,when the particle size was big enough, the activation energy will get smaller.The presence of MgCO3 accelerated the decomposition of CaCO3.The appropriate particle size for the decomposition of limestone in 81% air-19% CO2 atmosphere was less than 0.105 mm, with the optimum temperature of 890 ℃.