Static pressure fluctuations and flow mode in a three-phase fluidized bed.

Stochastic modeling of pressure fluctuations in a three‐phase fluidized bed

“…The pressure fluctuations, caused mainly by bubble motion, can be measured by a pressure probe (Nishiyama et al, 1987); the bubble behavior can be characterized by the autocorrelation function and power spectrum of signals from the probe. Moreover, stochastic characteristics of the bubble behavior can be reasonably determined from analyzing these autocorrelation functions (Nishiyama et al, 1987).…”

“…It was only natural, therefore, that statistical methods were adopted extensively to investigate the pressure fluctuations in fluidized beds. The earliest attempts defined indices for the quality of fluidization through the statistical analysis of pressure fluctuations (Shuster and Kisliak, 1952;Bailie et al, 1961;Sutherland, 1964;Winter, 1968;Moritomi et al, 1980;Nishiyama et al, 1987). Whitehead et al (1977) have indicated that analyzing the pressure fluctuations in a fluidized bed yields information useful for devising control strategies for it.…”

“…Whitehead et al (1977) have indicated that analyzing the pressure fluctuations in a fluidized bed yields information useful for devising control strategies for it. Kang Lirag and Littman (1971), Nishiyama et al (1987), and Fan et al (1990) calculated the probability density, autocorrelation and power spectral density functions of the pressure fluctuations off-line. The major frequency of the fluctuations was estimated from the resultant autocorrelation and power spectral density functions.…”

“…The notable among these stochastic models, which was proposed by Nishiyama et al (1987), considers that any pressure fluctuation signal due to the bubble movement consists of two components: a periodic component and a random component. It is a microscopic and multiplicative model based on the Markov process.…”