Circulation of solids and gas bypassing in an internally circulating fluidized bed with a draft tube

This paper presents a numerical study of gas and solid flow in an internally circulating fluidized bed (ICFB). Two-fluid Eulerian model with kinetic theory of granular flow option for solid phase stress closure and various drag laws were used to predict the hydrodynamic behavior of ICFB. 2D and 3D geometries were used to run the simulations. The 2D simulation results by various drag laws show that the Arastoopour and Gibilaro drag models able to predict the fluidization dynamics in terms of flow patterns, void fractions and axial velocity fields close to the experimental data. The effect of superficial gas velocity, presence of draft tube on solid hold-up distribution, solid circulation pattern, and variations in gas bypassing fraction for the 3D ICFB are investigated. The mechanism governing the solid circulation and solids concentration in an ICFB has been explained based on gas and solid dynamics obtained from the simulations. Predicted total granular temperature distributions in the draft tube and annular zones qualitatively agree with experimental data. The total granular temperature tends to increase with increasing solids concentration in the dilute region (ε < 0.1) and decreases with an increase of solids concentration in the dense region (ε > 0.1). In the dense zone, the decreasing trend in the granular temperature is mainly due to the reduction of the mean free path of the solid particles.

Download Full-text

Gasification of tire scrap and sewage sludge in a circulating fluidized bed with a draft tube

New Developments and Application in Chemical Reaction Engineering - Studies in Surface Science and Catalysis ◽

10.1016/s0167-2991(06)81659-9 ◽

2006 ◽

pp. 565-568 ◽

Cited By ~ 6

Author(s):

B.H. Song ◽

S.D. Kim

Keyword(s):

Sewage Sludge ◽

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Draft Tube

Download Full-text

Prediction of particle circulation rate in an internally circulating fluidized bed with a central draft tube

Powder Technology ◽

10.1016/j.powtec.2020.11.021 ◽

2021 ◽

Vol 380 ◽

pp. 497-505

Author(s):

Hongwei Chen ◽

Yangfan Song ◽

Yang Shi ◽

Xin Yang

Keyword(s):

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Draft Tube ◽

Circulation Rate

Download Full-text

Hydrodynamic Flow Characteristics in an Internally Circulating Fluidized Bed Gasifier

Journal of Energy Resources Technology ◽

10.1115/1.4041092 ◽

2018 ◽

Vol 141 (3) ◽

Cited By ~ 1

Author(s):

J. P. Simanjuntak ◽

K. A. Al-attab ◽

Z. A. Zainal

Keyword(s):

Fluidized Bed ◽

Flow Rate ◽

Circulating Fluidized Bed ◽

Draft Tube ◽

Three Dimensional ◽

Flow Characteristics ◽

Hydrodynamic Flow ◽

Orifice Diameter ◽

Circulation Rate ◽

Cfd Models

In this paper, the hydrodynamic flow inside an internally circulating fluidized bed (ICFBG) was characterized using experimental and three-dimensional computational fluid dynamics (CFD) models. Eulerian-Eulerian model (EEM) incorporating the kinetic theory of granular flow was implemented in order to simulate the gas–solid flow. A full-scale plexiglass cold flow experimental model was built to verify simulation results prior to the fabrication of the gasifier. Six parameters were manipulated to achieve the optimum design geometry: fluidization flow rate of the draft tube (Qdt), aeration flow rate of the annulus (Qan), initial bed static height (Hbs), draft tube height (Hdt), draft tube diameter (Ddt), and orifice diameter (Dor). The investigated parameters showed strong effect on the particle flow characteristics in terms of the pressure difference (ΔP) and solid circulation rate (Gs). The predicted results by simulation for the optimum case were in close agreement with experimental measurements with about 5% deviation. The results show that the ICFBG operated stably with the maximum Gs value of 86.6 kg/h at Qdt of 350 LPM, Qan of 150 LPM, Hbs of 280 mm, Hdt of 320 mm, Ddt of 100 mm, and Dor of 20 mm.

Download Full-text