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Title: Flow Regime Study in a High Density Circulating Fluidized Bed Riser with an Abrupt Exit

Abstract

Flow regime study was conducted in a 0.3 m diameter, 15.5 m height circulating fluidized bed (CFB) riser with an abrupt exit at the National Energy Technology Laboratory of the U.S. Department of Energy. Local particle velocities were measured at various radial positions and riser heights using an optical fiber probe. On-line measurement of solid circulating rate was continuously recorded by the Spiral. Glass beads of mean diameter 61 μm and particle density of 2,500 kg/m3 were used as bed material. The CFB riser was operated at various superficial gas velocities ranging from 3 to 7.6 m/s and solid mass flux from 20 to 550 kg/m2-s. At a constant riser gas velocity, transition from fast fluidization to dense suspension upflow (DSU) regime started at the bottom of the riser with increasing solid flux. Except at comparatively low riser gas velocity and solid flux, the apparent solid holdup at the top exit region was higher than the middle section of the riser. The solid fraction at this top region could be much higher than 7% under high riser gas velocity and solid mass flux. The local particle velocity showed downward flow near the wall at the top of the riser duemore » to its abrupt exit. This abrupt geometry reflected the solids and, therefore, caused solid particles traveling downward along the wall. However, at location below, but near, the top of the riser the local particle velocities were observed flowing upward at the wall. Therefore, DSU was identified in the upper region of the riser with an abrupt exit while the fully developed region, lower in the riser, was still exhibiting core-annular flow structure. Our data were compared with the flow regime boundaries proposed by Kim et al. [1] for distinguishing the dilute pneumatic transport, fast fluidization, and DSU.« less

Authors:
; ; ;  [1]
  1. REM Engineering Services
Publication Date:
Research Org.:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR (United States)
Sponsoring Org.:
USDOE - Office of Fossil Energy (FE)
OSTI Identifier:
915486
Report Number(s):
DOE/NETL-IR-2007-146
TRN: US200817%%380
DOE Contract Number:  
None cited
Resource Type:
Conference
Resource Relation:
Conference: 12th International Conference on Fluidization - New Horizons in Fluidization Engineering, Vancouver, BC, Canada, May 13-17, 2007
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 42 ENGINEERING; CIRCULATING SYSTEMS; FLUIDIZED BEDS; GLASS; OPTICAL FIBERS; TWO-PHASE FLOW; FLOW RATE

Citation Formats

Mei, J S, Shadle, L J, Yue, P C, and Monazam, E R. Flow Regime Study in a High Density Circulating Fluidized Bed Riser with an Abrupt Exit. United States: N. p., 2007. Web.
Mei, J S, Shadle, L J, Yue, P C, & Monazam, E R. Flow Regime Study in a High Density Circulating Fluidized Bed Riser with an Abrupt Exit. United States.
Mei, J S, Shadle, L J, Yue, P C, and Monazam, E R. Mon . "Flow Regime Study in a High Density Circulating Fluidized Bed Riser with an Abrupt Exit". United States. doi:. https://www.osti.gov/servlets/purl/915486.
@article{osti_915486,
title = {Flow Regime Study in a High Density Circulating Fluidized Bed Riser with an Abrupt Exit},
author = {Mei, J S and Shadle, L J and Yue, P C and Monazam, E R},
abstractNote = {Flow regime study was conducted in a 0.3 m diameter, 15.5 m height circulating fluidized bed (CFB) riser with an abrupt exit at the National Energy Technology Laboratory of the U.S. Department of Energy. Local particle velocities were measured at various radial positions and riser heights using an optical fiber probe. On-line measurement of solid circulating rate was continuously recorded by the Spiral. Glass beads of mean diameter 61 μm and particle density of 2,500 kg/m3 were used as bed material. The CFB riser was operated at various superficial gas velocities ranging from 3 to 7.6 m/s and solid mass flux from 20 to 550 kg/m2-s. At a constant riser gas velocity, transition from fast fluidization to dense suspension upflow (DSU) regime started at the bottom of the riser with increasing solid flux. Except at comparatively low riser gas velocity and solid flux, the apparent solid holdup at the top exit region was higher than the middle section of the riser. The solid fraction at this top region could be much higher than 7% under high riser gas velocity and solid mass flux. The local particle velocity showed downward flow near the wall at the top of the riser due to its abrupt exit. This abrupt geometry reflected the solids and, therefore, caused solid particles traveling downward along the wall. However, at location below, but near, the top of the riser the local particle velocities were observed flowing upward at the wall. Therefore, DSU was identified in the upper region of the riser with an abrupt exit while the fully developed region, lower in the riser, was still exhibiting core-annular flow structure. Our data were compared with the flow regime boundaries proposed by Kim et al. [1] for distinguishing the dilute pneumatic transport, fast fluidization, and DSU.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

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