Effect of Temperature on Hydrodynamics of a Gas-Solid Fluidized Bed

Effect of temperature on hydrodynamics of a gas-solid
fluidized bed

In this study, white alundum of diameter about 0.180
mm belonging to Geldart B classification powder was used to study the effect of
temperature on hydrodynamics of fluidized bed. Fluidization tests were
conducted at different temperatures (293-873 K) and different superficial gas
velocities, covering fixed bed state, bubbling, and turbulent fluidization
regime. Differential pressure transducer measuring the total bed pressure drop and
the home-made high-temperature electrical capacitance tomography sensor measuring
the cross section, 18 cm height above distribution plate, voidage of fluidized
bed were used to characterize the influence of temperature. Experimental
results indicated that not only gas properties had effect on performance of
fluidized bed, but interparticle force induced by temperature had significant
influence on the fluidized bed characteristics, alerting the fluidization
behaviour of the bed from Geldart group B behaviour to Geldart group A
behaviour. Pressure drop curves at 293 and 873 K were shown in Figure 1, pressure
drop overshoot indicated the behaviour change. Additionally, home-made
electrical capacitance tomography sensor was also used to measure the variation
of solids concentration and bubble diameters induced by the temperature. Figure
2 shows the variation of standard deviation of average solids concentration at 473,
673 and 873 K. It can be seen that the standard deviation of average solids
concentration were down then up at the same superficial velocity when the
fluidized bed temperature increasing. It can be owing to the interparticle
forces and gas properties induced by temperature. Consequently, the particle
properties induced by temperature and the gas properties should be seriously
considered when attempting to successfully design and operate gas-solids
fluidized bed at high temperature. More researches are undergoing. 

Figure 1 Pressure drop of fluidized bed at 293 and 873 K

Figure 2 Standard deviation of average solids concentration at
different temperature