Integrated Approach for Heat Transfer in Fluidized Bed Reactors

Abstract Thermal design of dual circulating fluidized bed reactors for carbon dioxide (CO2) capture was carried out. To handle large heat duties for regeneration, a thin rectangular reactor was proposed. For feasible thermal design, the effect of varying reactor thickness on the gas-solid flow and heat transfer of the thin rectangular fluidized bed was investigated. Reactor thickness of 10, 30, and 60 mm was tested. Numerical simulations were conducted to analyze the pressure difference, solid particle hold-up distribution, particle velocity, granular temperature, and heat transfer in detail. According to our results, when the reactor is between 10 mm and 30 mm thick, a large solid hold-up occurs adjacent to the narrow wall. This causes a large pressure difference due to the wall effect. Furthermore, the particle velocities were analyzed to evaluate that there is the two-dimensional (2D) particle mixing behaviors. On the other hand, in the case of reactors with a thickness of 60 mm, tuning flows occur adjacent to the narrow wall. This reduced the pressure difference and the three-dimensional (3D) particle mixing behaviors. This difference in particle behavior affected heat transfer. In the case of reactor thicknesses between 10 mm and 30 mm, the heat transfer increased with the reactor thickness. In particular, the heat transfer at the narrow wall of the reactor with a thickness of 10 mm was extremely low due to the low particle mixing. On the other hand, there was more heat transfer with a thickness at the 60 mm wall, despite the low solid hold-up.

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INCORPORATION OF A TWO-FLUX MODEL FOR RADIATIVE HEAT TRANSFER IN A COMPREHENSIVE FLUIDIZED BED SIMULATOR PART II: NUMERICAL RESULTS AND ASSESSMENT

Revista de Engenharia Térmica ◽

10.5380/reterm.v2i2.3476 ◽

2003 ◽

Vol 2 (2) ◽

pp. 49

Author(s):

J. A. Rabi ◽

M. L. De Souza-Santos

Keyword(s):

Heat Transfer ◽

Fluidized Bed ◽

Radiative Heat Transfer ◽

Radiative Heat ◽

Fluidized Bed Reactors ◽

Transfer Model ◽

New Developments ◽

Transfer Rates ◽

Gas Phases ◽

Flux Model

As shown in the first part of this paper, equations and considerations for a preliminary attempt to improve the treatment for radiative heat transfer of a previous comprehensive simulation program were presented. For that, the two-flux radiative heat transfer model was applied. In this second part, the new version of that program was tested against steady-state operations of real equipment. Numerical simulations were carried for two different fluidized-bed reactors: a coal-fed boiler and a wood-fed gasifier. Computational results obtained with that new version were compared with those obtained with the previous simulator version. Then, both sets of results were also compared with real operational data. Special attention was paid to the temperature profiles of each particle species present in the bed section carbonaceous, limestone and inert as well as to the radiative heat transfer rates between these solids. Effects on the temperature profiles of the gas phases emulsion and bubbles and on the equipment performance parameters were also investigated. Improvements related to the incorporation of two-flux model are assessed and discussed. New developments and extensions of this approach are indicated.

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Collision process details control the hydrodynamics and heat transfer in fluidized bed reactors

China PARTICUOLOGY ◽

10.1016/s1672-2515(07)60155-9 ◽

2005 ◽

Vol 3 (1-2) ◽

pp. 18

Author(s):

Masayuki Horio

Keyword(s):

Heat Transfer ◽

Fluidized Bed ◽

Fluidized Bed Reactors ◽

Collision Process

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Multi-scale heat transfer in fluidized bed reactors by Eulerian CFD modeling

Fuel ◽

10.1016/j.fuel.2014.09.027 ◽

2015 ◽

Vol 139 ◽

pp. 646-651 ◽

Cited By ~ 13

Author(s):

Wang Shuai ◽

Zhang Tianyu ◽

Liu Guodong ◽

Lu Huilin ◽

Sun Liyan

Keyword(s):

Heat Transfer ◽

Fluidized Bed ◽

Cfd Modeling ◽

Fluidized Bed Reactors ◽

Multi Scale

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INCORPORATION OF A TWO-FLUX MODEL FOR RADIATIVE HEAT TRANSFER IN A COMPREHENSIVE FLUIDIZED BED SIMULATOR PART II: NUMERICAL RESULTS AND ASSESSMENT

Revista de Engenharia Térmica ◽

10.5380/ret.v2i2.3476 ◽

2003 ◽

Vol 2 (2) ◽

Cited By ~ 1

Author(s):

J. A. Rabi ◽

M. L. De Souza-Santos

Keyword(s):

Heat Transfer ◽

Fluidized Bed ◽

Radiative Heat Transfer ◽

Radiative Heat ◽

Fluidized Bed Reactors ◽

Transfer Model ◽

Temperature Profiles ◽

Transfer Rates ◽

Gas Phases ◽

Flux Model

As shown in the first part of this paper, equations and considerations for a preliminary attempt to improve the treatment for radiative heat transfer of a previous comprehensive simulation program were presented. For that, the two-flux radiative heat transfer model was applied. In this second part, the new version of that program was tested against steady-state operations of real equipment. Numerical simulations were carried for two different fluidized-bed reactors: a coal-fed boiler and a wood-fed gasifier. Computational results obtained with that new version were compared with those obtained with the previous simulator version. Then, both sets of results were also compared with real operational data. Special attention was paid to the temperature profiles of each particle species present in the bed section carbonaceous, limestone and inert as well as to the radiative heat transfer rates between these solids. Effects on the temperature profiles of the gas phases emulsion and bubbles and on the equipment performance parameters were also investigated. Improvements related to the incorporation of two-flux model are assessed and discussed. New developments and extensions of this approach are indicated.

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