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Title: Fluidization quality analyzer for fluidized beds

Abstract

A control loop and fluidization quality analyzer for a fluidized bed utilizes time varying pressure drop measurements. A fast-response pressure transducer measures the overall bed pressure drop, or over some segment of the bed, and the pressure drop signal is processed to produce an output voltage which changes with the degree of fluidization turbulence. 9 figs.

Inventors:
;
Publication Date:
Research Org.:
Lockheed Martin Energy Syst Inc
OSTI Identifier:
87738
Patent Number(s):
US 5,435,972/A/
Application Number:
PAN: 8-171,270
Assignee:
Dept. of Energy, Washington, DC (United States) PTO; SCA: 420400; PA: EDB-95:119338; SN: 95001431580
DOE Contract Number:
AC05-84OR21400
Resource Type:
Patent
Resource Relation:
Other Information: PBD: 25 Jul 1995
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; FLUIDIZED BEDS; MONITORING; MEASURING INSTRUMENTS; DESIGN; PRESSURE MEASUREMENT; TURBULENT FLOW

Citation Formats

Daw, C.S., and Hawk, J.A. Fluidization quality analyzer for fluidized beds. United States: N. p., 1995. Web.
Daw, C.S., & Hawk, J.A. Fluidization quality analyzer for fluidized beds. United States.
Daw, C.S., and Hawk, J.A. 1995. "Fluidization quality analyzer for fluidized beds". United States. doi:.
@article{osti_87738,
title = {Fluidization quality analyzer for fluidized beds},
author = {Daw, C.S. and Hawk, J.A.},
abstractNote = {A control loop and fluidization quality analyzer for a fluidized bed utilizes time varying pressure drop measurements. A fast-response pressure transducer measures the overall bed pressure drop, or over some segment of the bed, and the pressure drop signal is processed to produce an output voltage which changes with the degree of fluidization turbulence. 9 figs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1995,
month = 7
}
  • A control loop and fluidization quality analyzer for a fluidized bed utilizes time varying pressure drop measurements. A fast-response pressure transducer measures the overall bed pressure drop, or over some segment of the bed, and the pressure drop signal is processed to produce an output voltage which changes with the degree of fluidization turbulence.
  • A simple, mass conservation-based, kinematic model is presented for accurately predicting both the onset of fluidization and the degree of (limit of) bed expansion in bubbling gas-solid fluidized beds. The model is consistant with inception correlations exisiting in the literature. Since the method has a sound physical basis, it might be expected to provide scaling between laboratory-scale fluidized beds and large-scale systems. This scaling ability, however, remains to be demonstrated as does the application to pressurized systems and where the terminal Reynolds numbers exceed 1000, (Archimedes numbers over about 3.2 x 10/sup 5/).
  • Accurate detection of minimum liquid fluidization is essential to the successful operation of gas-liquid-solid fluidized beds, especially when particle or liquid properties evolve. A gas-liquid-solid system of 3-mm glass beads exhibits three distinct flow regimes as the liquid velocity is increased: compacted, agitated and fluidized-bed regimes. Measurements showed that the bed is not fluidized in the agitated bed regime. Pressure gradient and bed height measurements do not provide the minimum liquid fluidization velocity; instead, they offer the velocity between the compacted and agitated bed regimes. Time-averaged signals are not reliable for determining the minimum liquid fluidization velocity. It can bemore » obtained from the standard deviation, the average frequency, the Hurst exponent and the V statistic of the cross-sectional average conductivity, which can be measured under many industrial conditions. Examples of applications of gas-liquid-solid fluidized bed reactors include coal liquefaction and petroleum hydrotreating.« less
  • In a rotating fluidized bed, unlike in a conventional fluidized bed, the granules are fluidized layer by layer from the (inner) free surface outward at increasing radius as the gas velocity is increased. This is a very significant and interesting phenomenon and is extremely important in the design of these fluidized beds. The phenomenon was first suggested in a theoretical analysis and recently verified experimentally in the authors' laboratory. However, in the first paper, the equations presented are too cumbersome and the influence of bed thickness is not clearly stated. In this note the authors present simplified equations, based onmore » that paper, for the pressure drop and the minimum fluidizing velocities in a rotating fluidized bed. Experimental data are also shown and compared with the theoretical model, and the effect of bed thickness is shown. Furthermore, an explanation for the observation of a maximum in the pressure drop vs. velocity curve instead of the plateau derived by Chen is proposed.« less
  • This report (RP8006-16) describes research into (1) turbulent fluidization for fine and coarse particles and (2) entrainment in fluidized systems. Both topics are important to many fluid-bed applications in the process industries. To carry out their investigations, researchers set up experimental equipment for a series of tests. Their approach included particle sampling, local dynamic pressure and pressure fluctuation measurements, and visual observations. Among the specific parameters they studied were superficial gas velocity, particle density, particle size, particle shape, column diameter, bed height, and interparticle forces. Test results indicated that the so-called ``turbulent regime`` for both coarse and fine particles doesmore » not exist, and there appears to be no distinct regime between slugging and fast fluidized beds. The absence of a discrete ``turbulent regime`` suggests that trends in industry designs at higher fluidization velocities can proceed without concern for hydrodynamic limitations. In carrying out these experiments, investigators also observed a high quantity of gas entrainment in the dip legs of test apparatus. They conducted further studies to define and predict this entrainment phenomenon.« less