Study On The Behavior Of Fluidization In A Fluidized Bed With Vertical Sieve Trays

In a self-developed S type vertical sieve tray fluidized bed,a study on cold model experiment of the behavior of gas-solid fluidization was carried out,using FCC catalysts and room air as fluidizing medium.The impact of parameters such as the gas velocity of tray hole,the circulation volume of catalysts,the structure of the bubble caps on elevated quantity was fully investigated;the influence of the gas velocity of tray hole,the circulation volume of catalysts and the structure of the bubble caps on pressure drop of the bed was studied too;the experiment data was then regressed,and by using dimensional analysis theory,gas-solid fluidization theory and a series of hypothesis conditions,a mathematical model of the pressure drop in the circulating fluidized bed was founded,and then the solving was carried out.The results showed that the fluidizing medium was fast fluidized within the vertical sieve tray fluidized bed where there was no bubble produced,the fluidization between the gas-solid two-phase was even and in a rather good condition.The elevated quantity of the vertical sieve tray’s bubble caps was the main factor that affected the pressure drop of the bed which rised with the increase of the elevated quantity.The elevated quantity of the caps increased with the rise of the mass flow rate of the catalysts,the pore size of the tray hole as well as the pore size of the caps.With the increase of the gas velocity of tray hole,the height of the bottom slot and the opening ratio of the cap,the elevated quantity increased at first but then decreased.The length of the cap,however,had little impact on the elevated quantity.The pressure drop increased with the increase of the mass flow rate of the solid particles as well as the increase of the gas velocity of tray hole,while decreased with the rise of the opening ratio and the pore size of the cap.And the length of the cap had little impact on the pressure drop of the bed.The calculated value from the established mathematical model of the pressure drop in the vertical sieve tray fluidized bed had given a good agreement with the results from the experiment with the absolute deviation no more than 15 percent.