Numerical Simulation Of Cross-domain Flow And Heat Transfer In An Internally Heated Pneumatic Spouted Bed

As an important means of fluidized drying technology,pneumatic and spouted bed have been widely used in various industries such as energy and chemical industry.As an important energy material,oil shale has always been concerned about its drying method and the development of drying equipment.Due to the poor contact of gas-solid between two phases in the annular zone of the spouted bed in the integrated pneumatic spouted bed combination drying,the heat transfer effect between the gas and solid in the annular zone is not good.In order to improve the heat transfer efficiency of oil shale,this paper will optimize the design of integrated pneumatic spouted bed combination drying,and get the internal heat integrated pneumatic spouted bed combination drying device.In this paper,the cross-domain operation characteristics of integrated pneumatic spouted bed were studied by combining with the experiment and Fluent software.The experiment and numerical simulation show that when the bed height is 50 mm,the particle motion state and pressure drop curve of the device are very similar to that of traditional spouting bed.When the bed height is 100 mm and 150 mm,the pressure drop curve will have a secondary mutation.For the 150 mm bed height,the shift gas velocity is 18m/s.Under this shift gas velocity,the particles start in a stable spout state and then transition to an unstable spout state.The flow pattern in the bed changes,and the shift gas velocity that leads to the secondary mutation of the pressure drop curve increases with the increase of the bed height.In this paper,the cross-domain flow characteristics of the internally heated integrated pneumatic spouted bed are simulated and analyzed,and the results show that the particles in the internal thermal integrated pneumatic spouted bed move more violent,and the dead zone area in the annulus area decreases.The addition of heat pipe affects the gas flow field nearby,resulting in eddy current phenomenon,which is conducive to the enhanced heat transfer between the gas and solid.With the increase of particle size,the gas velocity required for particle spouting increased,but the Granular temperature of particles and the turbulent kinetic energy of gas also increased,indicating that the turbulent motion of particles was more intense.From the change law of particle volume fraction with increasing particle size,it can be found that as the particle size increases,the uniformity of oil shale particle distribution decreases,which is not conducive to the fluidization of the particles in the bed.In this paper,the heat transfer characteristics of the internally heated integrated pneumatic spouted bed are simulated and analyzed,and the results show that under the same gas velocity,with the increase of oil shale particle size,the average particle temperature decreases.At the diameter of 2mm,the average temperature of oil shale particles increased with the increase of gas velocity of high-temperature gas.The optimal operating parameters of the optimized internal intergrated pneumatic spouted bed combination drying device are: the height of the stationary bed is 100 mm,the particle size of the oil shale is 2mm,and the air velocity at the inlet of the airflow pipe is 31m/s.