Solids circulation rate and static bed height in a riser of a circulating fluidized bed

Fluidization numbers varying from 0.84 to 1.68 were used in the loop seal valve of a bench-scale circulating fluidized bed (CFB) system to analyze the influence of the mono-chamber aeration mode on both the solids circulation rate and the static pressure drop inside the solids recycle device. Runs were carried out using 4 kg of overall solids inventory and particles of 183 µm in Sauter mean diameter, which were kept under fast fluidization regime at superficial gas velocity of 4 m/s. Results showed that the choice of the chamber to be aerated can noticeably affect the gas-solid hydrodynamics. In this sense, the analysis of variance applied on the experimental data indicated that the aeration into the recycle chamber of the loop seal offers lower levels of solids circulation rate but also allows to control it within a wider range of fluidization numbers and with less pressure drop or energy demand.

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PREDICTION OF SOLIDS CIRCULATION RATE IN THE RISER OF AN INTERNALLY CIRCULATING FLUIDIZED BED (ICFB)

Chemical Engineering Communications ◽

10.1080/00986440108912895 ◽

2001 ◽

Vol 188 (1) ◽

pp. 47-58 ◽

Cited By ~ 5

Author(s):

WON NAMKUNG ◽

CHRISTOPHE GUY ◽

ROBERT LEGROS

Keyword(s):

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Circulation Rate ◽

Solids Circulation Rate

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Effect of temperature on gas bypassing and solids circulation rate in an internally circulating fluidized bed

The Canadian Journal of Chemical Engineering ◽

10.1002/cjce.5450780601 ◽

2000 ◽

Vol 78 (6) ◽

pp. 1025-1031 ◽

Cited By ~ 8

Author(s):

Won Namkung ◽

Christophe Guy ◽

Fréadéaric Boisselle ◽

Robert Legros

Keyword(s):

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Effect Of Temperature ◽

Circulation Rate ◽

Solids Circulation Rate

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Radial Distribution of Liquid Velocity in a Liquid-Solids Circulating Fluidized Bed

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1020 ◽

2003 ◽

Vol 1 (1) ◽

Cited By ~ 5

Author(s):

Ying Zheng ◽

Jesse Zhu

Keyword(s):

Fluidized Bed ◽

Radial Distribution ◽

Circulating Fluidized Bed ◽

Liquid Velocity ◽

Circulation Rate ◽

Liquid Transport ◽

Solids Circulation Rate ◽

Fluidization Regime ◽

Radial Profiles ◽

Radial Nonuniformity

Local liquid velocity was measured in a liquid-solid circulating fluidized bed, with a Plexiglas riser column of 7.62 cm ID and 3.0 m in height, by a dual conductivity probe, with 508 micron glass beads. The results show that radial distribution of local liquid velocity in the LSCFB is nonuniform with higher liquid velocity at the axis and lower near the wall, compared to the more uniform radial profiles in both the conventional fluidization and the dilute liquid transport regimes. The radial nonuniformity increases with increasing liquid velocity and solids circulation rate in the LSCFB. A radial nonuniformity index, proposed by Zhu and Manyele (2001), was used to quantify the extent of the radial nonuniformity under different solids circulation rates and liquid flow rates. The radial nonuniformity index is used to qualify the radial distribution of liquid velocity. RNI values in the liquid-solid circulating fluidization regime are seen to be much higher than those in both the particulate fluidization regime and the dilute liquid transport regime, indicating the nonuniform radial distribution of local liquid velocity in the LSCFB. This illustrates the use of RNI as an effective measurement of the radial distribution of liquid velocity.

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An Investigation Into the Operation of the Twin-Exit Loop-Seal of a Circulating Fluidized Bed Boiler in a Thermal Power Plant and Its Design Implication

Journal of Energy Resources Technology ◽

10.1115/1.4000174 ◽

2009 ◽

Vol 131 (4) ◽

Cited By ~ 7

Author(s):

Prabir Basu ◽

Munish Chandel ◽

James Butler ◽

Animesh Dutta

Keyword(s):

Power Plant ◽

Fluidized Bed ◽

Thermal Power Plant ◽

Circulating Fluidized Bed ◽

Thermal Power ◽

Scale Model ◽

Circulation Rate ◽

Cfb Boiler ◽

Solids Circulation Rate ◽

New Findings

Loop-seal is a critical component of a circulating fluidized bed (CFB) boiler, and yet very little information on its working or design is available in published literature. Among the limited available information, none is on twin-exit loop-seal though it is one of the most commonly used loop-seal in large commercial CFB boilers. To circulate larger amounts of solids, a twin-exit loop-seal provides larger solids flow sections. It receives solids from one standpipe but delivers it through two recycle chambers and two delivery pipes. The present research was conducted in a twin-exit loop-seal of a 3.2 MWth CFB boiler operating in a thermal power plant for cofiring purpose. Data obtained in this industrial unit were supplemented with those collected in a single-exit bench-scale loop-seal in the authors’ laboratory from the single-exit loop-seal in a 65 t/h CFB boiler and a scale model of a 30 MW CFB boiler. The effect of recycle chamber’s aeration on the solids circulation rate was studied for several particle sizes. Results suggest that the total solids circulation rate does not increase proportionately with the increase in loop-seal discharge area provided by the twin-exit loop-seals. The linear horizontal velocities of solids and the minimum aeration in the recycle chambers are comparable to those measured in a single-exit loop-seal. The implication of these new findings on the design procedure of loop-seals is discussed.

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