Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446728
Title: The open-channel flow of fluidized solids.
Author: Abdul-Halim, B. H.
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 1978
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Abstract:
Studies of the open channel flow of a 77 μm mean diameter catalyst. and ash of wide size distribution with a mean diameter of 380 μm are reported. Earlier results with a 196 μ m sand have been re-interpreted. The catalyst and ash beds were fluidized at up to 3 Umf and 2.25 Umf respectively over a porous tile distributor. The horizontal experimental section was of width variable between 100 and 180mm. Flow behaviour was inferred from pressure drop measurements over channel lengths between 750 and 940mm and average be velocities of up to 500mms were reached. The shear stress at a section of the vertical wall of the experimental section was measured directly using a strain gauge and that across the distributor estimated from the difference between the total stress represented by the pressure drop along the experimental section and the wall shear stress. Comparison is also made with flow property measurements using a modified Brookfield viscometer Flow index increased with increase in fluidizing velocity. Thus the freely fluidized and flowing fluidized beds showed pseudo plastic flow characteristics and the flowing sand and ash beds also displayed dilatant characteristics at the higher fluidizing velocities tested. The apparent viscosity reduced with initial increase in gas flow rate passed through a minimum and then increased. However, the minimum was not reached over the range of test with either the flowing catalyst or ash bed experiments. Whereas the distributor shear stress was consistently lower than that at the wall in the catalyst experiments, it exceeded that at the wall in both the sand and ash experiments at low shear rates and its relative value then decreased to less than that at the wall as the shear rate increased. This is suggestive of slip at the distributor even at low shear rates with the catalyst. However, slip at the vertical wall is discounted from the visual observations made in the flowing beds. Bed depth was a significant factor, and flow behaviour was influenced by the width of the experimental channel. The flow behaviour will also be influenced by the form of distributor, but this was not examined in this work. Whilst there is reasonable correspondence between variation in shear stress measurements made in the modified Brookfield viscometer and directly at the channel wall, the viscometer reading is sensitive to the position of the rotor within the bed. This and the varying slip at the distributor in the flowing bed system precludes direct application of small scale test data in the design of open channel flow systems.
Supervisor: Not available Sponsor: Not available
Qualification Name: Doctoral Thesis - University of Birmingham. Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.446728  DOI: Not available
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