碳酸钙分解动力学的微型流化床与热重对比研究

Comparation of Calcium Carbonate Decomposition Kinetics Studied by Micro Fluidized Bed and by Thermogravimetric Analyzer

利用微型流化床反应分析仪(MFBRA)和热重分析仪(TGA)分别测定了空气中碳酸钙的等温与非等温反应,并采用不同的数据处理方法对其分解动力学进行了对比研究.MFBRA增强了反应过程中传热传质以及有效消除气体外扩散对反应的影响,其测得的活化能(E=138.35 kJ·mol^(-1))和指前因子(A=1.58×10^(5) s^(-1))均低于TGA(E=209.95 kJ·mol^(-1),A=8.95×10^(7) s^(-1))获得的结果,但两者所测得的活化能均在文献报道的120~280 kJ·mol^(-1)范围内.此外,两种仪器得到的最概然机理函数模型均为收缩几何模型(圆柱形对称)G(x)=1-(1-x)^(1/2),表明了MFBRA在气固反应动力学表征方面的有效性和可靠性.

The isothermal and non-isothermal reactions of calcium carbonate decomposition were determined by micro fluidized bed reaction analyzer(MFBRA)and thermogravimetric analyzer(TGA),respectively,and different data processing methods were adopted to calculate the reaction kinetics.MFBRA enhances heat and mass transfer and effectively eliminates the effect of gas external diffusion on the reaction,resulting in lower obviously activation energy(E=138.35 kJ/mol)and pre-exponential factor(A=1.58×10^(5) s^(-1))than those obtained by TGA(E=209.95 kJ/mol,A=8.95×10^(7)s^(-1)),but both of activation energies are in the range of 120-280 kJ mol^(-1) reported in the literatures.In addition,the most suitable mechanism function model in both TGA and MFBRA follows the shrinking core model(cylindrical symmetry)G(x)=1-(1-x)^(1/2),revealing the reliability and effectiveness of MFBRA for kinetic characterization of gas-solid reaction kinetics.