The characteristics and kinetics of coal and oil shale pyrolysis were comparatively studied by using a micro fluidized bed reaction analyzer(MFBRA).The isothermal differential model was first applied to calculate the ...The characteristics and kinetics of coal and oil shale pyrolysis were comparatively studied by using a micro fluidized bed reaction analyzer(MFBRA).The isothermal differential model was first applied to calculate the kinetic parameters of activation energy and frequency factor according to the major gas components during pyrolysis.The results showed that the major gas components released from coal and oil shale under the isothermal condition had different initiating and ending time points,and the difference was more significant under the programmed heating conditions.The shrinking core model allowed better fitting relevance for the coal pyrolysis,while the three-dimension model was more suitable for oil shale pyrolysis,indicating that the gases from the pyrolysis process of coal and oil shale might go through different reaction paths.The activation energy of oil shale pyrolysis was 36.96 kJ·mol^(−1),larger than the value of pyrolysis of the two coals,which was 21.16 and 32.17 kJ·mol^(−1),respectively.The above results justified that the oil shale pyrolysis with high ash contents was somehow more difficult to take place in terms of higher activation energy and the MFBRA could be a useful tool to give some insight into the intrinsic kinetics and reaction mechanisms of coal and oil shale pyrolysis.展开更多
Experiments on the solid-state reaction between iron ore particles and MgO were performed to investigate the coating mechanism of MgO on the iron ore particles＇ surface during fluidized bed reduction. MgO powders and...Experiments on the solid-state reaction between iron ore particles and MgO were performed to investigate the coating mechanism of MgO on the iron ore particles＇ surface during fluidized bed reduction. MgO powders and iron ore particles were mixed and compressed into briquettes and, subsequently, roasted at different temperatures and for different time periods. A Mg-containing layer was observed on the outer edge of the iron ore particles when the roasting temperature was greater than 1173 K. The concentration of Fe in the Mg-containing layer was evenly distributed and was approximately 10wt%, regardless of the temperature change. Boundary layers of Mg and Fe were observed outside of the iron ore particles. The change in concentration of Fe in the boundary layers was simulated using a gas–solid diffusion model, and the diffusion coefficients of Fe and Mg in these layers at different temperatures were calculated. The diffusion activation energies of Fe and Mg in the boundary layers in these experiments were evaluated to be approximately 176 and 172 k J/mol, respectively.展开更多
基金The study was conducted with the research programs financed by the National Natural Science Foundation of China(U1862107,21406264)Science Foundation of China University of Petroleum-Beijing(Grant No.2462018BJC003)R&D Program of China National Petroleum Corporation(LH-17-08-55-05).
文摘The characteristics and kinetics of coal and oil shale pyrolysis were comparatively studied by using a micro fluidized bed reaction analyzer(MFBRA).The isothermal differential model was first applied to calculate the kinetic parameters of activation energy and frequency factor according to the major gas components during pyrolysis.The results showed that the major gas components released from coal and oil shale under the isothermal condition had different initiating and ending time points,and the difference was more significant under the programmed heating conditions.The shrinking core model allowed better fitting relevance for the coal pyrolysis,while the three-dimension model was more suitable for oil shale pyrolysis,indicating that the gases from the pyrolysis process of coal and oil shale might go through different reaction paths.The activation energy of oil shale pyrolysis was 36.96 kJ·mol^(−1),larger than the value of pyrolysis of the two coals,which was 21.16 and 32.17 kJ·mol^(−1),respectively.The above results justified that the oil shale pyrolysis with high ash contents was somehow more difficult to take place in terms of higher activation energy and the MFBRA could be a useful tool to give some insight into the intrinsic kinetics and reaction mechanisms of coal and oil shale pyrolysis.
基金supported by the Fundamental Research Funds for the Central Universities (FRF-TP-15-009A2)the Project Funded by China Postdoctoral Science Foundation (2015M570931)+1 种基金the National Natural Science Fund Project of China (91534121)the National Major Scientific Instruments Special Plan (2011YQ12003907)
文摘Experiments on the solid-state reaction between iron ore particles and MgO were performed to investigate the coating mechanism of MgO on the iron ore particles＇ surface during fluidized bed reduction. MgO powders and iron ore particles were mixed and compressed into briquettes and, subsequently, roasted at different temperatures and for different time periods. A Mg-containing layer was observed on the outer edge of the iron ore particles when the roasting temperature was greater than 1173 K. The concentration of Fe in the Mg-containing layer was evenly distributed and was approximately 10wt%, regardless of the temperature change. Boundary layers of Mg and Fe were observed outside of the iron ore particles. The change in concentration of Fe in the boundary layers was simulated using a gas–solid diffusion model, and the diffusion coefficients of Fe and Mg in these layers at different temperatures were calculated. The diffusion activation energies of Fe and Mg in the boundary layers in these experiments were evaluated to be approximately 176 and 172 k J/mol, respectively.
