DECOMPOSITION OF NaHCO3 IN LABORATORY AND BENCH SCALE CIRCULATING FLUIDIZED BED REACTORS

Helmrich, Harald; Schügerl, K.; Janssen, K.

doi:10.1016/b978-0-08-031869-1.50019-3

Cited by 12 publications

(10 citation statements)

References 3 publications

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“…Solids mixing at the entrance appears to be insensitive to particle properties in contrast to the fully developed region. Helmrich et al (1986) modelled solids RTD data by using a loop reactor model which combined plug flow and stirred tank compartments. While such models accurately describe the experimental data and give an indication of the effects of riser operating conditions and geometry on axial solids mixing, they do not physically represent the actual mechanism of solids mixing observed in CFB risers.…”

Section: Solids Mixingmentioning

confidence: 99%

Hydrodynamics of circulating fluidized bed risers: A review

et al. 1995

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Any vessel in which solids are transported upward by a gas stream and then recycled to the bottom may be classified as a Circulating Fluidized Bed (CFB). We describe possible CFB operating regimes in the context of this broad classification and highlight commercial processes that employ CFB technology and potential applications. Process design and development require a fundamental understanding of gas and solids hydrodynamicssolids hold-up, mixing and velocity distribution. We discuss techniques used to measure solids mass flux, which is a critical parameter for both design and control. In the last decade, significant research efforts have been devoted to new experimental techniques to measure both gas and solids spatial and temporal distribution. We list these techniques and detail the different modelling approaches that have emerged based on the new data. Characterization of the data is still incomplete and the available models require further refinement to reliably predict the effect of scale, operating conditions and particle characteristics on hydrodynamics. N'importe quel contenant dans lequel des particules sont emportks dans la direction ascendante par un courant gazeux puis recyclkes par le bas peut Stre class6 c o m e un Lit Fluidisk Circulant (LFC). Nous dkrivons les rkgimes possibles des op6rations dans ces LFC en tenant compte de cette dkfinition ktendue et les prockddcs industriels existants et potentiels qui utilisent cette technologie des LFC. La conception et le dkveloppement des proctklks exigent une comprkhension fondamentale des hydrodynamics du gaz et des particulesrktention de solides, degrk de mklange et distribution des vitesses. Nous discutons les diffkrentes techniques utiliskes pour mesurer le taux de circulation de solide qui est un paramttre critique pour aussi bien le design que le contr6le. Durant le dernitres mks, un effort significatif'de recherche a kt6 consenti au dkveloppement de nouvelles techniques exp6rimentales pour mesurer les distributions temporelle et spatiale des diffkrentes caractkristiques du gaz et du solide. Nous reportons ces techniques et nous dktaillons le diffkrentes approches de modklisation qui ont kt6 introduites en se basant sur ces nouvelles donnks.La caradrisation de ces donnks est encore incompltte et les modkles existants doivent Stre encore raflids afin de pddire ad6quatement les effets d'khelle, des conditions @ratoires et des mactkristiques des particules sur I'hydrodynamique.

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Section: Solids Mixingmentioning

confidence: 99%

Hydrodynamics of circulating fluidized bed risers: A review

et al. 1995

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“…These authors applied the one-dimensional dispersion model of Levenspiel and Smith (1957) to obtain measures of solids diffusivity. Helmrich et al (1986) reported a double-peak RTD in their experiments using T. Hirama IS presently with Government Industrial Development Laboratory, Sapporo, Hokkaido. Japan.…”

Section: Introductionmentioning

confidence: 96%

Effects of operating conditions on longitudinal solids mixing in a circulating fluidized bed riser

Rhodes¹,

Zhou²,

Hirama³

et al. 1991

AIChE Journal

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“…A number of studies have been conducted on the hydrodynamics (for example, Li and Kwauk, 1980;Hartge et al, 1986;Weinstein et al, 1986;Rhodes and Geldart, 1987), and on heat transfer behavior (Grace, 1986;Basu et al, 1987;Bi et al, 1989;Wu et al, 1990) in the CFB. Relatively few studies, however, have been made on the mass transfer (Halder and Basu, 1988), and reactor design and modeling (Helmrich et al, 1986;Liu, 1989;Sun and Grace, 1990;Grace et al, 1990;Jiang et al, 1990).…”

Section: Introductionmentioning

confidence: 99%