Pressure Fluctuation Model of Fluidized Bed

Dynamic model was proposed for pressure fluctuations for a gas-solid fluidized bed. Transfer function for plenum pressure variation was obtained from the equations which described mass balance around the plenum, pressure drop through the distributor, and pressure at the bottom of the bed. Validity of the model was studied in spectrum domain comparing experimental results acquired from three-dimensional apparatus processing sand whose mean diameter was 360 microns. Spectrum analyses showed dominant values which decreased as superficial gas velocity increased at frequencies of 8 Hz and 17 Hz. Peak value at the lower frequency was related to the oscillation of the bed, and another peak at the higher frequency was due to the inlet gas flow. The model was highly consistent with experimental results both in free bubbling fluidization regime and in more intensive fluidized regime with higher gas velocity. An ARMA model for the bed including blower system was presented taking into account the blower dynamics estimated from the step response results.