Gas-solid fluidized bed separation is a highly efficient and clean technique for coal separation,and can effectively remove ash and sulfur contained gangue minerals from coal.However,the fine coal plugging distributor...Gas-solid fluidized bed separation is a highly efficient and clean technique for coal separation,and can effectively remove ash and sulfur contained gangue minerals from coal.However,the fine coal plugging distributor often leads to uneven fluidization and affects the separation effect.In this paper,different plugging ways were designed to study their effects on the fluidization characteristics and particle mixing.It was found that when the plugging phenomenon occurs,the minimum fluidization velocity of the fluidized bed gradually decreases as the plugging area enlarges.The difference between the top and the bottom of the bed minimum fluidization velocity increases accordingly,and a“stagnation phenomenon”occurs in the bed.The standard deviation of pressure fluctuations at the top of the bed is smaller than that at the bottom of the bed,which is the opposite of normal conditions.As the area of the plugging increases,the dead zone on the side wall of the fluidized bed significantly increases.The size of the dead zone is rapid reducing at the initial stage.It was noticed that the stratification of the low-density products is particularly affected by plugging,whereas the stratification of high-density products is not obviously influenced by certain conditions.展开更多
This study investigates the impact of mixing 0–1 mm fine coal with 0.15–0.3 mm magnetite powder to form a binary dense medium.The aim is to examine how the 0–1 mm fine coal influences the stability of vibration sep...This study investigates the impact of mixing 0–1 mm fine coal with 0.15–0.3 mm magnetite powder to form a binary dense medium.The aim is to examine how the 0–1 mm fine coal influences the stability of vibration separation in a fluidized bed and to achieve steady-state control of vibration fluidization.The vibration segregation behaviour of the binary dense medium under varying fine coal contents is analyzed in this work.The study discovers that the primary contributor to segregation is coal particles smaller than 0.5 mm.As the proportion of fine coal increases,upward movement becomes more pronounced,especially for particles smaller than 0.15 mm,where the upward segregation is most noticeable,with a peak mixing index of 8.06.The study confirms that the larger the particle size of fine coal,the higher the content limit for mixing with magnetite powder.According to studies on the process of fine coal segregation,coal particles larger than 0.5 mm move with the magnetite powder,and the mixing index remains below 3.Coal particles smaller than 0.5 mm fine coal will separate at a uniform speed in a stable environment produced by low vibration energy,with the top-level mixing index remaining constant at 26 after 6 min.Additionally,the study also examines how the fluidization of vibration separation is influenced by the segregation of 0–1 mm fine coal.The evidence shows that longitudinal density segregation within the binary dense medium competes with instantaneous density fluctuation.The longitudinal density distribution of the binary dense medium was found to be nearly uniform when the frequency was set to 25 Hz,amplitude to 2 mm,and upward gas velocity to 1.4 times the minimum fluidization velocity.The density fluctuation was found to be between 0 and 0.1 g/cm^(3).The best separation effect was achieved with fine coal particles ranging from 6 to 1 mm in size under these conditions.展开更多
In this paper,the variation of bubble size and number in the separation process of vibrated fluidized bed as well as the influence of bubble movement on the axial distribution of fine coal in different positions of th...In this paper,the variation of bubble size and number in the separation process of vibrated fluidized bed as well as the influence of bubble movement on the axial distribution of fine coal in different positions of the bed were studied.The result revealed that the size and number of bubbles is correlated with the fine coal separation effect in the separation process.When the bed is in a uniform and stable fluidized state,the size of bubbles in the separation process was in the range of 1-2.5 cm and the number of bubbles was reduced by nearly 50%,which is helpful to promote the stratification and segregation of fine coal.Thereby,after separation,the ash content of refined coal products of anthracite and 1/3 coking coal was reduced to 12.1% and 23.7% respectively,and the content of refined coal was up to 42.5% and 68.5% respectively,which show that the vibrated fluidized bed has a good separation performance,and can separate efficiently the coal of size−6+1 mm.展开更多
Gas–solid separation fluidized bed is a typical method for coal separation without water utilization.Geldart A particles is also considered as the ideal dense medium to strengthen separation efficiency.Fluidization s...Gas–solid separation fluidized bed is a typical method for coal separation without water utilization.Geldart A particles is also considered as the ideal dense medium to strengthen separation efficiency.Fluidization stability reflects the bed pressure fluctuations and the distribution of bubble and emulsion phases,affecting the separation performance.And the main frequency of pressure fluctuations can directly reflect the degree of pressure fluctuations.Therefore,the detailed fluidization stability is analyzed combined the method of standard deviation of pressure fluctuations,power spectral density,etc.,for Geldart A particles.The results showed that maintaining an appropriate gas velocity resulted in an average bed pressure of around 2000 Pa.The main frequency is mainly concentrated around 1–1.5 Hz.Finally,a prediction model of the main frequency of pressure fluctuations is established,and the error can be controlled within±0.15.The investigation further proved the stable fluidization of Geldart A particles and provides a method for predicting the main frequency of pressure fluctuations in the gas–solid separation fluidized bed.展开更多
基金the National Natural Science Foundation of China-Xinjiang Joint Foundation(No.U1903132)National Natural Science Foundation of China(No.51904298).
文摘Gas-solid fluidized bed separation is a highly efficient and clean technique for coal separation,and can effectively remove ash and sulfur contained gangue minerals from coal.However,the fine coal plugging distributor often leads to uneven fluidization and affects the separation effect.In this paper,different plugging ways were designed to study their effects on the fluidization characteristics and particle mixing.It was found that when the plugging phenomenon occurs,the minimum fluidization velocity of the fluidized bed gradually decreases as the plugging area enlarges.The difference between the top and the bottom of the bed minimum fluidization velocity increases accordingly,and a“stagnation phenomenon”occurs in the bed.The standard deviation of pressure fluctuations at the top of the bed is smaller than that at the bottom of the bed,which is the opposite of normal conditions.As the area of the plugging increases,the dead zone on the side wall of the fluidized bed significantly increases.The size of the dead zone is rapid reducing at the initial stage.It was noticed that the stratification of the low-density products is particularly affected by plugging,whereas the stratification of high-density products is not obviously influenced by certain conditions.
基金This work was supported by the National Natural Science Foundation of China(grant Nos.52474306,52220105008,52125403,52304306)Jiangsu Provincial Natural Science Foundation(grant No.BK20231073)Graduate Innovation Program Project of China University of Mining and Technology(grant No.2024WLJCRCZL100).
文摘This study investigates the impact of mixing 0–1 mm fine coal with 0.15–0.3 mm magnetite powder to form a binary dense medium.The aim is to examine how the 0–1 mm fine coal influences the stability of vibration separation in a fluidized bed and to achieve steady-state control of vibration fluidization.The vibration segregation behaviour of the binary dense medium under varying fine coal contents is analyzed in this work.The study discovers that the primary contributor to segregation is coal particles smaller than 0.5 mm.As the proportion of fine coal increases,upward movement becomes more pronounced,especially for particles smaller than 0.15 mm,where the upward segregation is most noticeable,with a peak mixing index of 8.06.The study confirms that the larger the particle size of fine coal,the higher the content limit for mixing with magnetite powder.According to studies on the process of fine coal segregation,coal particles larger than 0.5 mm move with the magnetite powder,and the mixing index remains below 3.Coal particles smaller than 0.5 mm fine coal will separate at a uniform speed in a stable environment produced by low vibration energy,with the top-level mixing index remaining constant at 26 after 6 min.Additionally,the study also examines how the fluidization of vibration separation is influenced by the segregation of 0–1 mm fine coal.The evidence shows that longitudinal density segregation within the binary dense medium competes with instantaneous density fluctuation.The longitudinal density distribution of the binary dense medium was found to be nearly uniform when the frequency was set to 25 Hz,amplitude to 2 mm,and upward gas velocity to 1.4 times the minimum fluidization velocity.The density fluctuation was found to be between 0 and 0.1 g/cm^(3).The best separation effect was achieved with fine coal particles ranging from 6 to 1 mm in size under these conditions.
基金Financial supports by the Found of the Jiangsu Excellent Youth Fund Project(Grant No.BK20200087)the National Natural Science Foundation of China(Grant Nos.51904298,U20A20304,51974306,51620105001)are gratefully acknowledged.
文摘In this paper,the variation of bubble size and number in the separation process of vibrated fluidized bed as well as the influence of bubble movement on the axial distribution of fine coal in different positions of the bed were studied.The result revealed that the size and number of bubbles is correlated with the fine coal separation effect in the separation process.When the bed is in a uniform and stable fluidized state,the size of bubbles in the separation process was in the range of 1-2.5 cm and the number of bubbles was reduced by nearly 50%,which is helpful to promote the stratification and segregation of fine coal.Thereby,after separation,the ash content of refined coal products of anthracite and 1/3 coking coal was reduced to 12.1% and 23.7% respectively,and the content of refined coal was up to 42.5% and 68.5% respectively,which show that the vibrated fluidized bed has a good separation performance,and can separate efficiently the coal of size−6+1 mm.
基金National Natural Science Foundation of China(grant Nos.52220105008,52261135540)China National Funds for Distinguished Young Scientists(grant No.52125403)+1 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province(grant No.SJCX23_1302)the Graduate Innovation Program of China University of Mining and Technology(grant No.2023WLJCRCZL081).
文摘Gas–solid separation fluidized bed is a typical method for coal separation without water utilization.Geldart A particles is also considered as the ideal dense medium to strengthen separation efficiency.Fluidization stability reflects the bed pressure fluctuations and the distribution of bubble and emulsion phases,affecting the separation performance.And the main frequency of pressure fluctuations can directly reflect the degree of pressure fluctuations.Therefore,the detailed fluidization stability is analyzed combined the method of standard deviation of pressure fluctuations,power spectral density,etc.,for Geldart A particles.The results showed that maintaining an appropriate gas velocity resulted in an average bed pressure of around 2000 Pa.The main frequency is mainly concentrated around 1–1.5 Hz.Finally,a prediction model of the main frequency of pressure fluctuations is established,and the error can be controlled within±0.15.The investigation further proved the stable fluidization of Geldart A particles and provides a method for predicting the main frequency of pressure fluctuations in the gas–solid separation fluidized bed.
