Pulsed-bed approach to fluidization

A critical review of the complex pressure fluctuation phenomenon in gas–solids fluidized beds

“…13 also shows that most natural frequency equations listed in Table 2 underestimate the natural frequency data in the literature, but agree reasonably well with the dominant frequency data. Based on the analysis of synchronized video images and visual observations, it was found (Baeyens and Geldart, 1974;Broadhurst and Roy et al (1990), Catalyst A Roy et al (1990), Vermiculite Roy et al (1990), Glass beads Musters (1974), Catalyst Musmara et al (1995), Glass beads Bi et al (1995), catalyst Kobayashi et al (1969) Wong and Baird (1971) Dominant Frequency Baskakov et al (1986) 1976; Noordergraaf et al, 1987;Kage et al, 1991;M'chirguiet al, 1997) that the dominant frequency from absolute pressure fluctuations generally corresponds to the bubble eruption frequency detected at the bed surface. The local pressure drops almost simultaneously in the upper and lower sections of the bed as bubbles break through the bed surface (Baskakov et al, 1986).…”

“…For turbulent flow Moritomi et al (1980) Baskakov et al (1986) f = 1 g Hmf Roy et al (1990) f = 1 4Hmf g RT p (1− ) Sun et al (1994) f = Roy et al (1990), Catalyst A Roy et al (1990), Vermiculite Roy et al (1990), Glass beads Musters (1974), Catalyst Musmara et al (1995), Glass beads Bi et al (1995), catalyst Kobayashi et al (1969) Wong and Baird (1971) Verloop and Heertjes (1974) Baskakov et al (1986) Roy et al (1990 the solids sloshing motion, namely, the axisymmetric mode and the antisymmetric mode, are simply the full-wave and half-wave of the standing waves of the solids in a cylindrical column. The surface wave frequency is related to the wave length and wave mode by f ∝ (g/ ) 0.5 , with the wave length related to the bubble size or the diameter of the column (Sun et al, 1994).…”

“…The coupling of pressure fluctuations in fluidized beds of pulsed gas supply has been explored since 1960s when the gas input pulsation was tested for improving the fluidization quality (Kobayashi et al, 1969;Wong and Baird, 1971). As shown in Fig.…”

“…A simple approach for a vibrating fluidized bed is to treat both the bed and the vibrator as a second-order spring system (Ryzhkov and Tolmachev, 1983;Wang et al, 2002). Experimental data showed that there existed two distinctive peak frequencies in the power Roy et al (1990), Catalyst Roy et al (1990), Vermiculite Roy et al (1990), Glass beads Musters(1974), Catalyst Musmaraet al(1995), Glass beads Bi et al (1995), catalyst Kobayashi et al (1969) Wong and Baird (1971) spectrum of local pressure fluctuations from the vibrating fluidized bed, with one corresponding to the vibration frequency and the other to the natural frequency of the fluidized bed. A resonance frequency is reached when the vibration frequency becomes the same as the natural frequency of the fluidized bed.…”

Enhanced fluidization of nanoparticles with gas phase pulsation assistance

“…As compared to the original technique, where the total flow oscillates over time, the partial flow pulsation has been found to be easier to control and more effective in tackling defluidization of the cohesive particles (Akhavan et al, 2007;Akhavan et al, 2009). There are different techniques for introducing pulsation in a fluidized bed, such as using rotating disk (Nitz and Taranto, 2007) or a moving double plate distributor (Koksal and Vural, 1998), using an array of solenoid valves (Massimilla et al, 1966) or a single solenoid valve (Kobayashi et al, 1970;Wong and Baird, 1971;Coppens and van Ommen, 2003;Akhavan et al, 2006, Akhavan et al, 2007Akhavan et al, 2009), while the later being the most common and the simplest one.…”