Wavelet Analysis Of Pressure Fluctuation In A Bubbling Fluidized Bed

Pressure fluctuation is one of the most important parameters in the design and operation of gas-solid fluidized bed. The accuracy and response frequency of pressure sensor is very high and it's demands for operation are not heavy. So the complexity of multi-phase hydrodynamics in fluidized bed can be researched further by taking advantage of unusual method on the analysis of pressure fluctuation signal in the bed.For Geldard D type sand, pressure fluctuations were measured at different ratio of holes in the distributor, different superficial velocity and height in the bed. Furthermore, statistics analysis, Fast Fourier Transformation (FFT)of pressure fluctuation in the bubbling fluidized bed were conducted, which made us find a method of calculating the standard difference of pressure fluctuation to estimate the height of jet in the bed. And through Fourier transformation on the pressure fluctuation of the test point in the plenum, three main frequency band was gotten that is bubble formation frequency band, eruption frequency band and the main fluctuation frequency band causing by the bed natural frequency.On the base of the conclusion of Fourier transformation, by using wavelet pacKage transformation, the signal of the three key frequency band was picked up respectively and their fluctuation energy Eigenvalues was calculated then found the effect of superficial velocity and distributor on the bubble formation, coalescence and bubble eruption. As well as the pressure fluctuation energy of the three key frequency band varied along the bed axes.At last, the energy of the bubble formation frequency band was compared with the bubble model which shows the reliability of the analysis methods mentioned above.