A new approach to jet phenomena gas entrainment and recirculation in a bidimensional spouted fluidized bed

Abstract

Although gas jets injected into fluid beds fluctuate, previous models assumed that they were steady. A new model separates the bed in a zone in which the jet is never present and a zone in which the jet fluctuates (a point in this zone will alternately be in the jet and in the emulsion phase). Its predictions matched the rate of gas entrainment into the jet and the rate of gas recirculation between emulsion and jet which were observed in a large 2 dimensional bed equipped with a "V" grid and a central jet.Des modbles anterieurs ont IaissC supposer que les jets de gaz injectis dans des lits fluides sont stables alors qu'ils fluctuent. Un nouveau modble &pare le lit en une zone dans laquelle le jet n'est jamais present et une zone dans laquelle le jet fluctue (un point dans cette zone sera alternativement dans le jet et dans la phase d'kmulsion). Les predictions du modble sont en accord avec la vitesse d'entrainement du gaz dans le jet et la vitesse de recirculation du gaz centre I'Cmulsion et le jet. Ces deux vitesses ont CtC observees dans un grand lit bidimensionnel avec une grille en "V" et un jet central.

Dispersion characteristics of dissimilar materials in a fluidized bed with unevenly distributed fluidizing air

“…The circulation was controlled by producing an imbalance in the air supplies to different zones of the distributor, tilting the distributor (so that the flow is up the slope), or the use of a spout as a pump. The three methods mentioned above have been employed as the main ways to induce an internal circulating flow in fluidized beds [3][4][5][6][7][10][11][12][13][14][15][16]. Thus, this fluidized bed is called an ICFB.…”

Experimental study on solid circulation in a multiple jet fluidized bed

“…Several intrusive and non intrusive techniques have been applied to quantify these parameters in experimental fluidized beds setups. Some of these techniques include photographs and visual analysis,1, 11, 12, 17–20 pitot tubes,12, 18, 21 fiber optic probes,4, 22–27 tracer particles,7, 21, 28, 29 tracer gas,19, 30 gamma‐ray densitometer,15, 31 positron emission particle tracking,32, 33 x‐ray tomography,34, 35 digital image analysis,36–39 and particle‐image velocimetry (PIV) 40, 41. Most of these experimental studies have been conducted using single jet spouted beds.…”

Modelagem e simulação de regeneradores industriais

“…O entendimento do fenômeno do jato é portanto essencial para o design dos leitos fluidizados (Freychet et al, 1989). Segundo Freychet et a/.…”

“…A quarta proposta, sugerida por Freychet (1989), considera a flutuação do jato. O modelo separa o leito em duas zonas: uma zona na qual o jato flutua (isto é, num ponto deste leito tem-se alternadamente jato e grid), e uma zona na qual o jato nunca aparece.…”