Experimental investigation of gas-particle flows through diffusers in the freeboard region of fluidized beds

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:5563219

Kale, S R

An experimental study on the effects of straight walled diffusers on elutriation and flow properties in the freeboard region of fluidized beds was conducted as a possible means of reducing elutriation. A bed 150 mm x 150 mm in cross section, 915 mm high followed by 615 mm long diffuser and 305 mm long straight section was constructed. Glass beads (50-100 ..mu..m diameter) were fluidized by air at atmospheric pressure in the bubbling regime. Elutriation rate measurements with an isokinetic sampler indicated: 1) an exponential increase in elutriation rate with increasing air velocity, independent of bed height and diffuser configuration; and 2) a monotonic decrease in elutriation rate for diffusers located far downstream of the bed surface. These observations indicate significant changes from established one phase flow modes. Gas-phase velocity profiles were obtained for a 0.36 m high bed with the diffuser located far downstream of the bed surface. A single component Laser-Doppler Anemometer was used to measure the streamwise velocity component for four diffuser configurations (straight, 20/sup 0/, 40..pi.., and 60/sup 0/ full opening angles), with and without the bed. The general structure of the freeboard flow was studied by introducing smoke into the bed. None of the diffusers exhibited separation effects in the presence of the bed.

• OSTI ID: 5563219
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400* -- Engineering-- Heat Transfer & Fluid Flow
DIFFUSERS
ELUTRIATION
FLOW RATE
FLUID FLOW
FLUIDIZED BED
GAS FLOW
SEPARATION PROCESSES