Gas-solid Fluidized Bed Coal Beneficiator(GFBCB)process is a crucial dry coal beneficiation fluidization technology.The work employs the GFBCB process alongside a novel Geldart A^(-)dense medium,consisting of Geldart ...Gas-solid Fluidized Bed Coal Beneficiator(GFBCB)process is a crucial dry coal beneficiation fluidization technology.The work employs the GFBCB process alongside a novel Geldart A^(-)dense medium,consisting of Geldart A magnetite particles and Geldart C ultrafine coal,to separate small-size separated objects in the GFBCB.The effects of various operational conditions,including the volume fraction of ultrafine coal,the gas velocity,the separated objects size,and the separation time,were investigated on the GFBCB's separation performance.The results indicated that the probable error for 6∼3 mm separated objects could be controlled within 0.10 g/cm^(3).Compared to the traditional Geldart B/D dense medium,the Geldart A/A^(-)dense medium exhibited better size-dependent separation performance with an overall probable error 0.04∼0.12 g/cm^(3).Moreover,it achieved a similar separation accuracy to the Geldart B/D dense medium fluidized bed with different external energy for the small-size object beneficiation.The work furthermore validated a separation density prediction model based on theoretical derivation,available for both Geldart B/D dense medium and Geldart A/A^(-)dense medium at different operational conditions.展开更多
Dense medium cyclone(DMC)is the working horse in coal industry.In practice,it is usually operated under constant pressure and the operational conditions(mainly medium-to-coal(M:C)ratio and oper-ational pressure)need t...Dense medium cyclone(DMC)is the working horse in coal industry.In practice,it is usually operated under constant pressure and the operational conditions(mainly medium-to-coal(M:C)ratio and oper-ational pressure)need to be adjusted according to coal washability data(mainly coal particle size and density distributions).Nonetheless,until now it is still not well understood how the M:C ratio would affect the performance of DMCs especially under the practical conditions.In this work,the effect of M:C ratio is for the first time numerically studied under conditions similar to plant operation by using both tra-ditional and coarse-grained(CG)combined approach of computational fluid dynamics(CFD)and discrete element method(DEM),called as traditional CFD-DEM and CG CFD-DEM,in which the flow of coal par-ticles is modelled by DEM or CG DEM which applies Newton's laws of motion to individual particles and that of medium flow by the conventional CFD which solves the local-averaged Navier-Stokes equations,allowing consideration of particle-fluid mutual interaction and particle-particle collisions.Moreover,impulse and momentum connection law is used to achieve energy conservation between traditional CFD-DEM and CG CFD-DEM.It is found that under constant pressure,the M:C ratio affects DMC perfor-mance significantly.The specific effect depends on coal washability or coal type.Under extremely low M:C ratio,the phenomenon that high-quality coal product is misplaced to reject is successfully repro-duced,which has been observed in plants in Australian coal industry and called as"low-density tail".Moreover,strategies are proposed to mitigate the"low-density tail"phenomenon based on the model.展开更多
基金National Natural Science Foundation of China(grant Nos.52220105008,52104276)China National Funds for Distinguished Young Scientists(grant No.52125403).
文摘Gas-solid Fluidized Bed Coal Beneficiator(GFBCB)process is a crucial dry coal beneficiation fluidization technology.The work employs the GFBCB process alongside a novel Geldart A^(-)dense medium,consisting of Geldart A magnetite particles and Geldart C ultrafine coal,to separate small-size separated objects in the GFBCB.The effects of various operational conditions,including the volume fraction of ultrafine coal,the gas velocity,the separated objects size,and the separation time,were investigated on the GFBCB's separation performance.The results indicated that the probable error for 6∼3 mm separated objects could be controlled within 0.10 g/cm^(3).Compared to the traditional Geldart B/D dense medium,the Geldart A/A^(-)dense medium exhibited better size-dependent separation performance with an overall probable error 0.04∼0.12 g/cm^(3).Moreover,it achieved a similar separation accuracy to the Geldart B/D dense medium fluidized bed with different external energy for the small-size object beneficiation.The work furthermore validated a separation density prediction model based on theoretical derivation,available for both Geldart B/D dense medium and Geldart A/A^(-)dense medium at different operational conditions.
基金the financial supports provided by Shandong University,Northwestern Polytechnical University Laboratory Open Fund(grant No.6142701200203)Shandong Provincial Natural Science Foundation,(grant No.ZR2020ME107),Natural Science Foundation of Jjiangsu Province(grant No.BK20180287)China Association for Science and Technology"Young Talent Support Project".
文摘Dense medium cyclone(DMC)is the working horse in coal industry.In practice,it is usually operated under constant pressure and the operational conditions(mainly medium-to-coal(M:C)ratio and oper-ational pressure)need to be adjusted according to coal washability data(mainly coal particle size and density distributions).Nonetheless,until now it is still not well understood how the M:C ratio would affect the performance of DMCs especially under the practical conditions.In this work,the effect of M:C ratio is for the first time numerically studied under conditions similar to plant operation by using both tra-ditional and coarse-grained(CG)combined approach of computational fluid dynamics(CFD)and discrete element method(DEM),called as traditional CFD-DEM and CG CFD-DEM,in which the flow of coal par-ticles is modelled by DEM or CG DEM which applies Newton's laws of motion to individual particles and that of medium flow by the conventional CFD which solves the local-averaged Navier-Stokes equations,allowing consideration of particle-fluid mutual interaction and particle-particle collisions.Moreover,impulse and momentum connection law is used to achieve energy conservation between traditional CFD-DEM and CG CFD-DEM.It is found that under constant pressure,the M:C ratio affects DMC perfor-mance significantly.The specific effect depends on coal washability or coal type.Under extremely low M:C ratio,the phenomenon that high-quality coal product is misplaced to reject is successfully repro-duced,which has been observed in plants in Australian coal industry and called as"low-density tail".Moreover,strategies are proposed to mitigate the"low-density tail"phenomenon based on the model.
