Circulating fluidized model

Figure 54. Solid fraction profile comparison between pressurized circulating fluidized bed combustor and one-half size scale model based on simplified scaling law. (Glicksman et al., 1995.)...

Ake, T. R., and Glicksman, L. R., Scale Model and Full Scale Test Results of a Circulating Fluidized Bed Combustor, Proc. 1988 Seminar on Fluidized Bed Comb. Technol. for Utility Appl., EPRI, 1-24-1 (1989)... 

Chen, J. C., Cimini, R. J., and Dou, S. H., A Theoretical Model for Simultaneous Convective and Radiative Heat Transfer in Circulating Fluidized Beds, Circ. Fluid. Bed Tech. II, 255-262 (1988)... 

Mahalingan, M., and Kolar, A. K., Heat Transfer Model for Membrane Wall of a High Temperature Circulating Fluidized Bed, Circ. Fluid. Bed Tech. Ill, 239-246 (1990)... 

Patience, G. S., and Mills, P. L., Modelling of Propylene Oxidation in a Circulating Fluidized-Bed Reactor, New Developments in Selective Oxidation II, p. 1 (1994)... 

The height of the dense phase L is obtained by a pressure balance around the complete circulating fluidized bed loop. Good agreement is seen with this model and the existing data in the field. 

Yang, W. C., A Model for the Dynamics of a Circulating Fluidized Bed Loop, Second Int. Conf. on Circulating Fluidized Bed, Compiegne, France (1988)... 

CASH CBM CBO CBPC CC CCB CCM CCP CDB CEC CFBC CFC CFR CMM COP CSH CT Calcium aluminosilicate hydrate Coal bed methane Carbon burn-out Chemically-bonded phosphate ceramics Carbonate carbon Coal combustion byproducts Constant capacitance model Coal combustion product Citrate-dithionate-bicarbonate Cation exchange capacity Circulating fluidized bed combustion Chlorofluorocarbon Cumulative fraction Coal mine methane Coefficient of performance Calcium silicate hydrate Collision theory... 

Develop a model for an authothermic circulating fluidized-bed (CFB) reformer for the production of hydrogen from heptane and a MATLAB code for the design of the unit. 

Marschall KJ, Mleczko L. CFD modeling of an internally circulating fluidized-bed reactor. Chem Eng Sci 1999 54 2085-2093. 

Zhang, N., EMMS-based Meso-Scale Mass Transfer Model and Its Application to Circulating Fluidized Bed Combustion Simulation, Ph.D. thesis (in Chinese), Institute of Process Engineering, Chinese Academy of Sciences, Beijing (2010). Zhang, J., Ge, W. and Li, J., Chem. Eng. Sci. 60(11), 3091-3099 (2005). 

Rudolph, V., Chong, Y. O. and Nicklin, D. J. (1991). Standpipe Modelling for Circulating Fluidized Beds. In Circulating Fluidized Bed Technology III. Ed. Basu, Horio and Hasatani. Oxford Pergamon Press. 

In the emulsion phase/packet model, it is perceived that the resistance to heat transfer lies in a relatively thick emulsion layer adjacent to the heating surface. This approach employs an analogy between a fluidized bed and a liquid medium, which considers the emulsion phase/packets to be the continuous phase. Differences in the various emulsion phase models primarily depend on the way the packet is defined. The presence of the maxima in the h-U curve is attributed to the simultaneous effect of an increase in the frequency of packet replacement and an increase in the fraction of time for which the heat transfer surface is covered by bubbles/voids. This unsteady-state model reaches its limit when the particle thermal time constant is smaller than the particle contact time determined by the replacement rate for small particles. In this case, the heat transfer process can be approximated by a steady-state process. Mickley and Fairbanks (1955) treated the packet as a continuum phase and first recognized the significant role of particle heat transfer since the volumetric heat capacity of the particle is 1,000-fold that of the gas at atmospheric conditions. The transient heat conduction equations are solved for a packet of emulsion swept up to the wall by bubble-induced circulation. The model of Mickley and Fairbanks (1955) is introduced in the following discussion. 

The heat transfer behavior in a spouted bed (see 9.8) is different from that in dense-phase and circulating fluidized bed systems as a result of the inherent differences in their flow structures. The spouted bed is represented by a flow structure that can be characterized by two regions the annulus and the central spouting region (see Chapter 9). The heat transfers in these two regions are usually modeled separately. For the central spouting region, the correlation of Rowe and Claxton (1965) can be used for Repf > 1,000... 

Subbarao, D. and Basu, P. (1986). A Model for Heat Transfer in Circulating Fluidized Beds. Int. J. Heat Mass Transfer, 29,487. 

For the case of horizontal gas mixing, Werther and co-workers [70, 71] have shown that, for the bed solids they used (quartz sand, dp = 0.13 mm, Geldart group B), horizontal gas mixing in the top part of the circulating fluidized bed in the core zone can be described by the model for gas dispersion in turbulent singlephase flow [72]. The Peclet number... 

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