Relative contribution of variables affecting the reaction in fluid bed contactors

Miyauchi, Terukatsu; Furusaki, Shintaro

doi:10.1002/aic.690200605

Cited by 29 publications

(21 citation statements)

References 26 publications

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“…For a constant bubble diameter, the surface of the interphase between the bubble and dense phase and therefore the mass transfer is easier to calculate. As also stated by Miyauchi and Furusaki (1974) and Werther (1983), accurate modeling of the bed becomes possible only when the assumed bubble size is realistic, which is easily accomplished with constant values.…”

Section: X-ray Measurements Of the Bubble Diametermentioning

confidence: 95%

Influence of vertical internals on a bubbling fluidized bed characterized by X-ray tomography

Maurer

Wagner

Ommen

et al. 2015

International Journal of Multiphase Flow

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Section: X-ray Measurements Of the Bubble Diametermentioning

confidence: 95%

Influence of vertical internals on a bubbling fluidized bed characterized by X-ray tomography

Maurer

Wagner

Ommen

et al. 2015

International Journal of Multiphase Flow

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“…Several models have been proposed for the fluidized bed freeboard, reaction (Miyauchi and Furusaki, 1974; Ford et al, 1977; Yates and Rowe, 1977; deLasa and Grace, 1979; Beer et al, 1980; Rajan and Wen, 1980). However, those models have been either based on too simplified solid entrainment phe-nomena or require additional experimental measurements to determine the parameters.…”

Section: (41)mentioning

confidence: 99%

“…The importance of freeboard region in a fluidized bed reactor has been shown by several investigators (Miyauchi and Furusaki, 1974;Ford et al, 1977;Yates and Rowe, 1977;de Lasa and Grace, 1979). For a fast reaction, the freeboard region could contribute 50% or more in the overall conversion of the gas phase catalytic reaction (Yates and Rowe, 1977).…”

Section: Introductionmentioning

confidence: 95%

“…However, the freeboard reaction models proposed have been either based on simplified solid en trainment phenomena or require experimental measurement of the parameters. For example, in the model proposed by Miyauchi and Furusaki (1974), it is required to determine experimentally the solid concentration profile along the freeboard. Yates and Rowe (1977), on the other hand, assumed a constant solid concentration profile in the freeboard.…”

Section: Introductionmentioning

confidence: 99%

“…Most of the investigators (Miyauchi and Furusaki, 1974;Yates and Rowe, 1977;de Lasa and Grace, 1979;Beer et al, 1980) used either a plug flow or complete-mixing flow model. Rajan and Wen (1980), on the other hand, assumed the equal-sized compartment-in-series model or the axial dispersion model for the gas hydrodynamics in the freeboard.…”

Section: Introductionmentioning

confidence: 99%

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Model of solid gas reaction phenomena in the fluidized bed freeboard

Chen

Wen

1982

AIChE Journal

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periods N. Thus, the net transfer decreases for both a decrease in N and an increase in amplitude b.Our results show net diffusive transfer is somewhat decreased (proportional to €2) by corrugations if the perimeter length is fixed. However, from Figure 3 we see that corrugations may also cause LITERATURE CITED Crank, J., The Mathematics of Dijjusim, Clarendon Press, Oxford Goldstein, S., Modern Deoelopments an Fluid Dynamics, 1, Clarendon Morse, P. M., and H. is presented to describe the chemical reaction and hydrodynamics occurring in the freeboard of a fluidized bed. A comparison of experimental data on the amount of particles elutriated and the concentration profiles of SO, and NO, obtained from the freeboard of fluidized bed coal combustion (FBC) by the Babcock & Wilcox Company with the calculation based on the proposed model to include the effect of interaction among the entrained particles is desirable. More experimental data with chemical reactions in the freeboard are needed to validate the model for a p plications to fluidized bed catalytic reactors. SCOPEWhen bubbles burst at the fluidized bed surface, particles are entrained in the freeboard region. The entrained particles with a terminal velocity greater than the actual gas velocity will reach a certain height within the freeboard before they fall back into the bed. However, those particles with a terminal velocity smaller than the actual gas velocity will be elutriated and carried out of the bed. Because of good solid-gas contact in the C Y Wen IS deceased

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Axial distribution of reactivity inside a fluid‐bed contactor

1976

Self Cite

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The axial distribution of reactivity inside a fluid-bed contactor is studied for the hydrogenation of ethylene. The reactivity is large near the surface of the dense phase. The significant effect of the dilute phase, or the free board region, is verified experimentally, and the contact efficiency in the transition zone and in the dilute phase is obtained. The contact efficiency was approximated by T~ = 1 -0.75(c,/~,d~)O.~. The temperature rise in the dilute phase is measured in the small reactor. The transition zone between the dense and dilute phases is almost isothermal, but it is found that temperature increases in the dilute phase. Toei et al., 1972). Some of the models originate from basic studies on the behavior of bubbles inside the bed, and these are referred to as physical bubble models by Rowe (1972) who compared them with arbitrary two-phase models. A comparison of these models shows that the main differences between these models are related to whether or not some fraction of the catalyst is in direct contact with the bubble gas, the extent of axial mixing in each phase, and the axial change in bubble size. SHINTARO FURUSAKI TATSUJIRecently, Miyauchi (1974 a, b) proposed the concept of successive contact, taking account of catalyst particles suspended above the dense bed. This effect is important because of the good contact in the suspending zone (called the dilute phase). According to this theory, the reaction proceeds first in the dense phase in poor contact with the catalyst, then in the dilute phase in good contact. According to the theory, Miyauchi and Furusaki (1974) calculated conversions using the HHU or the contact efficiency. Experimental data previously obtained (Lewis et al., 1959;Van Swaay and Zuiderweg, 1972) were compared successfully with the calculation. The importance of the catalyst suspended in the dilute phase in controlling the selectivity was also discussed. This paper presents experimental verification of the successive contact by the hydrogenation of ethylene on MS-Ni catalyst. This proof is essential in pursuing the analysis of fluid-bed contactors and is examined in detail. If the efficiency in the dilute phase is much higher than that in the dense phase as shown above, control of the reactivity in the dilute phase by the use of fines is considered useful in determining the optimal operation of fluid-bed contactors. This seems one of the reasons of utilizing fine particles in a fluid bed. This point is briefly discussed. CONCLUSIONS AND SIGNIFICANCEIn studying the operation of a fluid-bed reactor by the concept of the successive contact, it is important to study the axial distribution of reactivity inside the bed. This is done by moving the axial position of the nozzle, through which one of the reactants, CzH4, is introduced into the fluid bed. By this method, the reactivity in the dilute phase is proved large, especially for the case of large reaction rates. The transition zone between the dense and dilute phases is found to be quite effective. The effective reactivity in t...

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Relative contribution of variables affecting the reaction in fluid bed contactors

Cited by 29 publications

References 26 publications

Influence of vertical internals on a bubbling fluidized bed characterized by X-ray tomography

Influence of vertical internals on a bubbling fluidized bed characterized by X-ray tomography

Model of solid gas reaction phenomena in the fluidized bed freeboard

Axial distribution of reactivity inside a fluid‐bed contactor

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