Gas-solid separation fluidized beds are important for coal cleaning through the removal of ash-forming impurities.Homogeneous fluidization is considered as an ideal separation method because it results in fewer pressu...Gas-solid separation fluidized beds are important for coal cleaning through the removal of ash-forming impurities.Homogeneous fluidization is considered as an ideal separation method because it results in fewer pressure fluctuations and smaller bubbles.And Geldart C ultrafine powder could further intensify the fluidization stability of Geldart A particles.Thus,the present work provides a breakthrough in the density adjustment method in the gas-solid separation field,namely,combining Geldart A magnetite particles and Geldart C fine coal particles as a novel dense medium.The results showed that the addition of ultrafine coal effectively increased the overall expansion of the dense phase by the adhesion of the coal particles on the surfaces of the magnetite particles.To comprehensively understand the difference in the dense phase expansion ratio between the Geldart B/D and Geldart A particles,the flow regime was investigated to determine the transition point of homogeneous expansion using various dense media.The propagation velocities of the shock and continuity waves were analyzed using the theory of elastic systems.A quantitative criterion is proposed to identify the transition point.Based on the error analysis,the available data in the literature and the present work gave an overall in 5×10^(−5) error range compared to the prediction data.Overall,this research provides a comprehensive understanding of homogeneous fluidization characteristics using a novel dense medium and a reliable quantitative transition criterion of the flow regime for Geldart B/D and Geldart A particles in a gas-solid separation fluidized bed.展开更多
Dry coal separation has become essential in China because it does not consume water and it reduces environmental pollution. In this study, a method for improving fluidization quality in a fluidized bed separator using...Dry coal separation has become essential in China because it does not consume water and it reduces environmental pollution. In this study, a method for improving fluidization quality in a fluidized bed separator using a micropore sponge is proposed. The separator is used for fine coal beneficiation. The pressure drop across the distributor and bed fluidization characteristics were analyzed to evaluate fluidization quality. The beneficiation efficiency for fine coal was further investigated by using a laboratory-scale fluidized bed with and without a micropore sponge. With the sponge, the highest pressure drop fluctuation factor decreased from 0.23 to 0.16, indicating an improvement in density stability. The modified separation method reduced the ash content of a sample of fine coal from 23.83% to 10.70%. The probable error efficiency value E for -6 + 3 mm coal was 0.12g/cm^3, close to the efficiency error values reported for other dry-beneficiation techniques. The separation results show that using a sponge in the fluidized bed can readily improve the efficiency of fine coal beneficiation.展开更多
基金supported by China National Funds for Distinguished Young Scientists(52125403)Natural Science Foundation of Jiangsu Province(BK20200651)+1 种基金National Natural Science Foundation of China(52104276,52261135540,52220105008)International Postdoctoral Exchange Fellowship Program(PC2021086).
文摘Gas-solid separation fluidized beds are important for coal cleaning through the removal of ash-forming impurities.Homogeneous fluidization is considered as an ideal separation method because it results in fewer pressure fluctuations and smaller bubbles.And Geldart C ultrafine powder could further intensify the fluidization stability of Geldart A particles.Thus,the present work provides a breakthrough in the density adjustment method in the gas-solid separation field,namely,combining Geldart A magnetite particles and Geldart C fine coal particles as a novel dense medium.The results showed that the addition of ultrafine coal effectively increased the overall expansion of the dense phase by the adhesion of the coal particles on the surfaces of the magnetite particles.To comprehensively understand the difference in the dense phase expansion ratio between the Geldart B/D and Geldart A particles,the flow regime was investigated to determine the transition point of homogeneous expansion using various dense media.The propagation velocities of the shock and continuity waves were analyzed using the theory of elastic systems.A quantitative criterion is proposed to identify the transition point.Based on the error analysis,the available data in the literature and the present work gave an overall in 5×10^(−5) error range compared to the prediction data.Overall,this research provides a comprehensive understanding of homogeneous fluidization characteristics using a novel dense medium and a reliable quantitative transition criterion of the flow regime for Geldart B/D and Geldart A particles in a gas-solid separation fluidized bed.
文摘Dry coal separation has become essential in China because it does not consume water and it reduces environmental pollution. In this study, a method for improving fluidization quality in a fluidized bed separator using a micropore sponge is proposed. The separator is used for fine coal beneficiation. The pressure drop across the distributor and bed fluidization characteristics were analyzed to evaluate fluidization quality. The beneficiation efficiency for fine coal was further investigated by using a laboratory-scale fluidized bed with and without a micropore sponge. With the sponge, the highest pressure drop fluctuation factor decreased from 0.23 to 0.16, indicating an improvement in density stability. The modified separation method reduced the ash content of a sample of fine coal from 23.83% to 10.70%. The probable error efficiency value E for -6 + 3 mm coal was 0.12g/cm^3, close to the efficiency error values reported for other dry-beneficiation techniques. The separation results show that using a sponge in the fluidized bed can readily improve the efficiency of fine coal beneficiation.
