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Title: Distributor for multistage fluidized beds

Abstract

This patent describes a multibed fluidized bed system. It comprises a fluidized bed vessel having a casing surrounding a first distributor and a second distributor downstream from the first distributor; a first bed material placed on the first distributor and a second bed material placed on the second distributor; each of the bed materials having an angle of repose; and wherein the angle formed by the substantially straight elongated tubular passages and the upper surface is less than the angle of repose of the second bed material.

Inventors:
Publication Date:
OSTI Identifier:
7171734
Patent Number(s):
US 5122346; A
Application Number:
PPN: US 7-521579
Assignee:
NOV; NOV-92-041090; EDB-92-154905
Resource Type:
Patent
Resource Relation:
Patent File Date: 10 May 1990
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 42 ENGINEERING; COAL; FLUIDIZED-BED COMBUSTION; FLUIDIZED BEDS; TECHNOLOGY ASSESSMENT; CARBONACEOUS MATERIALS; CHEMICAL REACTIONS; COMBUSTION; ENERGY SOURCES; FOSSIL FUELS; FUELS; MATERIALS; OXIDATION; THERMOCHEMICAL PROCESSES; 014000* - Coal, Lignite, & Peat- Combustion; 421000 - Engineering- Combustion Systems

Citation Formats

Wormser, A. Distributor for multistage fluidized beds. United States: N. p., 1992. Web.
Wormser, A. Distributor for multistage fluidized beds. United States.
Wormser, A. 1992. "Distributor for multistage fluidized beds". United States. doi:.
@article{osti_7171734,
title = {Distributor for multistage fluidized beds},
author = {Wormser, A.},
abstractNote = {This patent describes a multibed fluidized bed system. It comprises a fluidized bed vessel having a casing surrounding a first distributor and a second distributor downstream from the first distributor; a first bed material placed on the first distributor and a second bed material placed on the second distributor; each of the bed materials having an angle of repose; and wherein the angle formed by the substantially straight elongated tubular passages and the upper surface is less than the angle of repose of the second bed material.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1992,
month = 6
}
  • The characteristics of the distributor pressure drop in a fluidized bed corresponding to perforate distributor plates with regular and irregular distributor design were studied. Distributor pressure drops were measured in an empty bed and beds with different fluidizing particles or bed heights. The design variables tested included the open area ratio, hole size, hole lay-out, plate thickness and design irregularity. The characteristics of distributor pressure drop corresponding to abnormal operating conditions, i.e., hole blocking and channeling, were also examined. The results indicate that the open area ratio is the most critical parameter governing the plate pressure drop for a regularmore » distributor and that the design irregularity has a strong effect on the distributor behavior when particles are present. The study has given rise to criterion for uniform distribution across the distributor holes.« less
  • A plate-type gas distributor for fluidizing a bed of particulate matter is described for use in elevated superficial velocity applications. The distributior comprises an assembly of plates or sheets formed into troughs and into deflector baffles which overlie the edge of adjacent troughs to form modules arranged in longitudinal rows. The troughs and the baffles are spaced in a predetermined manner by joining struts or ribs. A circuitous gas flow path is defined by the slit between each deflector baffle and adjacent troughs. The minimum spacing between adjacent troughs is chosen so that the fluid flow velocity through the troughmore » spacing at design point is equal to or greater than the terminal velocity of the fluidized particles.« less
  • An analysis is performed on the validity of the axial dispersion model (ADM) to quantify mass transfer and mixing in three-phase fluidized beds of different particle sizes. The magnified mass transfer effects observed near the distributor invalidate the ADM as a realistic model for three-phase fluid beds. A two-zone model (T-ZM) based on the present experimental findings has proven to account far more satisfactorily for these effects. Regardless of the model considered, volumetric mass transfer coefficients (K /SUB L/ a) increase with the gas (V /SUB g/ ) and liquid (V /SUB I/ ) superficial velocities. Bubble columns and dilutemore » three-phase fluidized beds of 0.5-cm particles exhibit higher mass transfer rates than three-phase fluidized beds of 0.1- and 0.3-cm particles under the same flow rates.« less
  • This paper reports the effect of flow nonuniformities existing near the distributor of a liquid fluidized bed containing very low-density particles ([rho][sub s] = 1.05 g/mL) which has been investigated experimentally. Immobilized enzyme or cell bioreactors operated as liquid fluidized beds often employ low-density particles as the support matrix containing the immobilized biocatalyst. With poorly designed multihole distributors, dead zones can be created which seriously undermine the performance of the bioreactor due to the lack of nutrients. Design guidelines are provided for distributors to minimize the inlet flow disturbances, and hence eliminate potential distributor region problems. As a result, themore » dispersion model, which is normally used for design purposes, can then be applied.« less