Zwietering's equation for the suspension of porous particles and the use of curved blade impellers

Ibrahim, S. and Jasnin, S.N. and Wong, S.D. and Baker, I.F. (2012) Zwietering's equation for the suspension of porous particles and the use of curved blade impellers. International Journal of Chemical Engineering, 2012. pp. 1-13. ISSN 1687-8078

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The minimum speed for just-suspension, N js, of porous palm shell-activated carbon (PSAC) particles has been determined in a 15 cm diameter cylindrical tank using a 6-curved blade (6CB) impeller, compared to a 6-blade downpumping mixed-flow (6MFD) impeller and a Rushton turbine (6DT). The particles size ranged from 0.751.00 mm, 1.001.40 mm, and 1.402.36 mm with concentrations between 0 and 5 by weight. The 6CB being a radial impeller performed similarly to 6DT in terms of speed and power requirement at just-suspension, and particles distribution on the base. The 6MFD, with power requirement 100 to 200 less than the radial impellers, was the most efficient for suspending the particles, as usually reported for the range of solid concentrations used here. Specific power per unit mass for all three impellers showed reduction towards minima as the concentration of particles increased. The geometric factor, S, values agreed reasonably with published data, when the particle density was adjusted taking into account water filling the pores of the submerged activated carbon. This result means that Zwietering's equation can be used to predict suspension for porous particles with adjustment to the particle density. S values for curved-blade impellers are presented for the first time. © 2012 S. Ibrahim et al.

Item Type: Article
Additional Information: Export Date: 13 February 2014 Source: Scopus Art. No.: 749760 Language of Original Document: English Correspondence Address: Ibrahim, S.; Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia; email: References: Kolar, V., Studies on mixing X: Suspending solids particles in liquids by means of mechanical agitation (1961) Collection of Czechoslovak Chemical Communications, 26, pp. 613-627; Shimizua, K.T.K., Takahashi, K., Suzukia, E., Nomura, T., Effect of baffle geometries on crystal size distribution of aluminum potassium sulfate in a seeded batch crystallizer (1999) Journal of Crystal Growth, 197 (4), pp. 921-926. , 2-s2.0-0033099788 10.1016/S0022-0248(98)00884-7; Wu, J., Graham, L., Wang, S., Parthasarathy, R., Energy efficient slurry holding and transport (2010) Minerals Engineering, 23 (9), pp. 705-712. , 2-s2.0-77955305686 10.1016/j.mineng.2010.04.008; Chapple, D., Kresta, S.M., Wall, A., Afacan, A., The effect of impeller and tank geometry on power number for a pitched blade turbine (2002) Chemical Engineering Research and Design, 80 (4), pp. 364-372. , DOI 10.1205/026387602317446407; Greaves, M., Loh, V.Y., Power consumption effect in three phase mixing (1984) Institution of Chemical Engineers Symposium Series, (89), pp. 69-96; Nienow, A.W., Konno, M., Bujalski, W., Studies on three-phase mixing: A review and recent results (1986) Chemical Engineering Research and Design, 64 (1), pp. 35-42; Chapman, C.M., Nienow, A.W., Cooke, M., Middleton, J.C., Particle-gas-liquid mixing in stirred vessels part iii: Three phase mixing (1983) Chemical Engineering Research and Design, 61 (3), pp. 167-181; Dohi, N., Takahashi, T., Minekawa, K., Kawase, Y., Power consumption and solid suspension performance of large-scale impellers in gas-liquid-solid three-phase stirred tank reactors (2004) Chemical Engineering Journal, 97 (2-3), pp. 103-114. , DOI 10.1016/S1385-8947(03)00148-7; Ibrahim, S., Nienow, A.W., The effect of viscosity on particle suspension in an aerated stirred vessel with different impellers and bases (2010) Chemical Engineering Communications, 197 (4), pp. 434-454. , 2-s2.0-71449127538 10.1080/00986440903245914; Brucato, A., Cipollina, A., Micale, G., Scargiali, F., Tamburini, A., Particle suspension in top-covered unbaffled tanks (2010) Chemical Engineering Science, 65 (10), pp. 3001-3008. , 2-s2.0-77950595705 10.1016/j.ces.2010.01.026; Baldi, G., Conti, R., Alaria, E., Complete suspension of particles in mechanically agitated vessels (1978) Chemical Engineering Science, 33 (1), pp. 21-25. , DOI 10.1016/0009-2509(78)85063-5; Chudacek, M.W., Relationships between solids suspension criteria, mechanism of suspension, tank geometry, and scale-up parameters in stirred tanks (1986) Industrial and Engineering Chemistry Fundamentals, 25 (3), pp. 391-401. , 2-s2.0-0022505368; Chudacek, M.W., Solids suspension behaviour in profiled bottom and flat bottom mixing tanks (1985) Chemical Engineering Science, 40 (3), pp. 385-392. , DOI 10.1016/0009-2509(85)85100-9; Conti, R., Sicardi, S., Specchia, V., Effect of the stirrer clearance on particle suspension in agitated vessels (1981) Chemical Engineering Journal, 22 (3), pp. 247-249. , 2-s2.0-49149136836; Rieger, F., Effect of particle content on agitator speed for off-bottom suspension (2000) Chemical Engineering Journal, 79 (2), pp. 171-175. , 2-s2.0-0034283105 10.1016/S1385-8947(00)00171-6; Gray, D.J., Impeller clearance effect on off-bottom particle suspension in agitated vessels (1987) Chemical Engineering Communications, 61, pp. 152-158; Ibrahim, S., Nienow, A.W., Particle suspension in the turbulent regime: The effect of impeller type and impeller/vessel configuration (1996) Trans IChemE, 74 (6), pp. 679-688. , 2-s2.0-0030239355; Ibrahim, S., Nienow, A.W., Suspension of microcarriers for cell culture with axial flow impellers (2004) Chemical Engineering Research and Design, 82 (9), pp. 1082-1088. , DOI 10.1205/cerd.82.9.1082.44161; Ibrahim, S., Nienow, A.W., Comparing impeller performance for solid-suspension in the transitional flow regime with Newtonian fluids (1999) Chemical Engineering Research and Design, 77 (8), pp. 721-727. , DOI 10.1205/026387699526863; Wu, J., Zhu, Y., Pullum, L., Impeller geometry effect on velocity and solids suspension (2001) Chemical Engineering Research and Design, 79 (8), pp. 989-997. , DOI 10.1205/02638760152721857; Armenante, P.M., Nagamine, E.U., Effect of low off-bottom impeller clearance on the minimum agitation speed for complete suspension of solids in stirred tanks (1998) Chemical Engineering Science, 53 (9), pp. 1757-1775. , DOI 10.1016/S0009-2509(98)00001-3, PII S0009250998000013; Zwietering, T.N., Suspending of solid particles in liquid by agitators (1958) Chemical Engineering Science, 8 (3-4), pp. 244-253. , 2-s2.0-0001416524; Wu, J., Zhu, Y.G., Pullum, L., Suspension of high concentration slurry (2002) AIChE Journal, 48 (6), pp. 1349-1352. , DOI 10.1002/aic.690480620
Uncontrolled Keywords: Cylindrical tanks, Geometric factors, Palm shell-activated carbon, Particle densities, Particles distribution, Power requirement, Rushton turbines, Solid concentrations, Activated carbon, Impellers, Porous materials, Turbomachine blades, Suspensions (fluids).
Subjects: T Technology > T Technology (General)
T Technology > TA Engineering (General). Civil engineering (General)
Divisions: Faculty of Engineering
Depositing User: Mr Jenal S
Date Deposited: 10 Mar 2014 06:35
Last Modified: 03 Jul 2017 08:45

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