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The effect of particle shape on solid entrainment in gas-solid fluidisation
Dissertation (MEng)--University of Pretoria, 2008.
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University of Pretoria
2013
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| _version_ | 1867613461241921536 |
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| access_status_str | Open Access |
| author2 | Du Toit, Elizabeth Louisa |
| author_browse | Du Toit, Elizabeth Louisa |
| author_facet | Du Toit, Elizabeth Louisa |
| collection | Thesis |
| dc_rights_str_mv | © University of Pretoria 2008 E1069/ |
| description | Dissertation (MEng)--University of Pretoria, 2008. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/27612 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:36:30.912Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/27612 The effect of particle shape on solid entrainment in gas-solid fluidisation Du Toit, Elizabeth Louisa wouter.devos@up.ac.za Nicol, Willie De Vos, Wouter Phillip Fischer-tropsch Gas-solid fluidisation Particle shape description Entrainment Particle shape UCTD Dissertation (MEng)--University of Pretoria, 2008. The entrainment rate of Ferrosilicone (FeSi) particles was measured in a 140 mm perspex column with air as the fluidising medium. Two different types of FeSi were used, namely atomised FeSi, which is mostly spherical in shape with smooth surfaces, and milled FeSi, which is irregular with rough surfaces. Both the FeSi mixtures had the same solid density and the similar average particle diameters ranging from 38 µm to 50 µm. The size and density of these particles put them on the border between Geldart A and Geldart B powders, similar to the high temperature Fischer-Tropsch catalyst. The atomised FeSi had a slightly higher concentration in fines (8.6% vs 1.8%), but except for the difference in particle shape, the two mixtures had otherwise very similar physical properties. A substantial difference in entrainment rate was measured between the atomised and milled FeSi, where the atomised had an entrainment rate of about six times higher than the milled FeSi throughout the range of superficial velocities tested. It was shown that the higher entrainment rate cannot be attributed only to the higher fines concentration, but that the difference in particle shape had a significant effect on the entrainment rate. Several two dimensional shape characterisation techniques were used in attempt to quantify the difference between the atomised and the milled FeSi. Of these the particle circularity managed to differentiate the best between the two particle mixtures. The circularities of the atomised and the milled FeSi were found to be 0.782 and 0.711 respectively. The measured circularity was used instead of a sphericity to adjust for the effect of particle shape on the terminal velocity of the particles. The adjusted terminal velocity was then used in the elutriation rate constant correlations to see which of the popular correlations in literature predicts the entrainment rate of the FeSi the best. All of the correlations gave a poor performance in predicting the measured entrainment rates. The two correlations that performed the best were that of Choi et al. (1999) (AARE = 72.6%) and Geldart et al. (1979) (AARE = 79%). It was concluded that single particle drag and single particle terminal velocities are not adequate to incorporate the effect of particle shape on entrainment rate. The method i by which shape affects entrainment rate therefore deserves further investigation. Further studies should also be done to develop a three dimensional shape descriptor that predicts bulk behaviour better. Chemical Engineering unrestricted 2013-09-07T11:49:54Z 2008-09-09 2013-09-07T11:49:54Z 2008-04-11 2008-09-09 2008-08-28 Dissertation a 2008 E1069/gm http://hdl.handle.net/2263/27612 http://upetd.up.ac.za/thesis/available/etd-08282008-144243/ © University of Pretoria 2008 E1069/ application/pdf University of Pretoria |
| spellingShingle | Fischer-tropsch Gas-solid fluidisation Particle shape description Entrainment Particle shape UCTD The effect of particle shape on solid entrainment in gas-solid fluidisation |
| title | The effect of particle shape on solid entrainment in gas-solid fluidisation |
| title_full | The effect of particle shape on solid entrainment in gas-solid fluidisation |
| title_fullStr | The effect of particle shape on solid entrainment in gas-solid fluidisation |
| title_full_unstemmed | The effect of particle shape on solid entrainment in gas-solid fluidisation |
| title_short | The effect of particle shape on solid entrainment in gas-solid fluidisation |
| title_sort | effect of particle shape on solid entrainment in gas solid fluidisation |
| topic | Fischer-tropsch Gas-solid fluidisation Particle shape description Entrainment Particle shape UCTD |
| url | http://hdl.handle.net/2263/27612 http://upetd.up.ac.za/thesis/available/etd-08282008-144243/ |