Axial mixing coefficients in gas phase under nitrogen-water two-phase flow conditions at high pressure were measured in a packed column (0.15?m diameter,8.4?m high, with a 2.1?m packed section) by the technique of pul...Axial mixing coefficients in gas phase under nitrogen-water two-phase flow conditions at high pressure were measured in a packed column (0.15?m diameter,8.4?m high, with a 2.1?m packed section) by the technique of pulse injection of hydrogen. The packing was 350?Y Mellapak, manufactured by the Tianjin UnivTech Co. Ltd.. Nitrogen and water flowed countercurrently through the column at gas rates from 0.03 to 0.15?m·s -1 ,and liquid rates from 17.0 to 75.0?m 3·m -2 ·h -1 . The operation pressure varied from 0.10 to 1.70?MPa.The hydrogen concentration in gas phase was detected continuously by means of thermal conductivity. The one dimensional diffusion model was used for smoothing the experimental response curves with 7 per cent average errors. The experimental data showed that the axial mixing coefficient in gas increased with the increase of the interstitial velocity and the operation pressure. This trend may be due to the increase of the density and the viscosity of the nitrogen under high pressure. Practically no effect of the water loading on the axial mixing coefficient was observed.展开更多
The mechanism of liquid phase back-mixing in the liquid-solid fluidized bed has been studied.The radial parabolic distribution of liquid velocity is found to be the main motivation of particles’circulating movement w...The mechanism of liquid phase back-mixing in the liquid-solid fluidized bed has been studied.The radial parabolic distribution of liquid velocity is found to be the main motivation of particles’circulating movement which in trun causes the liquid back-mixing.The liquid back-mixing can be reduced by evening the radial distribution of liquid velocity.This is achieved by a hetero-pores distributor which has a resistant coefficient distribution analogous to that of liquid velocity.The experimental result shows that the hetero-pores distributor reduces the liquid back- mixing effectively.展开更多
文摘Axial mixing coefficients in gas phase under nitrogen-water two-phase flow conditions at high pressure were measured in a packed column (0.15?m diameter,8.4?m high, with a 2.1?m packed section) by the technique of pulse injection of hydrogen. The packing was 350?Y Mellapak, manufactured by the Tianjin UnivTech Co. Ltd.. Nitrogen and water flowed countercurrently through the column at gas rates from 0.03 to 0.15?m·s -1 ,and liquid rates from 17.0 to 75.0?m 3·m -2 ·h -1 . The operation pressure varied from 0.10 to 1.70?MPa.The hydrogen concentration in gas phase was detected continuously by means of thermal conductivity. The one dimensional diffusion model was used for smoothing the experimental response curves with 7 per cent average errors. The experimental data showed that the axial mixing coefficient in gas increased with the increase of the interstitial velocity and the operation pressure. This trend may be due to the increase of the density and the viscosity of the nitrogen under high pressure. Practically no effect of the water loading on the axial mixing coefficient was observed.
文摘The mechanism of liquid phase back-mixing in the liquid-solid fluidized bed has been studied.The radial parabolic distribution of liquid velocity is found to be the main motivation of particles’circulating movement which in trun causes the liquid back-mixing.The liquid back-mixing can be reduced by evening the radial distribution of liquid velocity.This is achieved by a hetero-pores distributor which has a resistant coefficient distribution analogous to that of liquid velocity.The experimental result shows that the hetero-pores distributor reduces the liquid back- mixing effectively.
