In this work

a multi-resolution analysis method was used to quantitatively characterize the fluctuating pressure signals generated in a slurry bed

and thereby to evaluate the local gas hold-up values.The method was implemented by following three major steps: (1) by wavelet transform

the pressure signals were decomposed into different scales with different resolutions;(2) by FFT the prime frequency was determined from the power spectral density function (PSDF) diagram of the pressure fluctuation signals;(3) the major scale corresponding to the prime frequency was then used to reconstruct and map the denoised data of the original signals into a frame of local intermittency measure (LIM) at a dominant resolution.It was demonstrated that the intermittent passage of bubbles at a local position of the bed is related to changes in the LIM values.By choosing a proper threshold value for the LIM distribution

the gas hold-up was estimated at four radial locations and hence the area averaged gas hold-up was obtained. A comparison of the gas hold-up [JP]values obtained by means of the LIM analysis and the conventional pressure drop method showed good agreement

indicating that the larger fluctuations in the bed could be attributed to the bubble motions.This work presented a simple method for gas hold-up determination in slurry beds operated under high temperature and/or pressure conditions.