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Spouted bed hydrodynamics at temperatures up to 580 C

University of British Columbia

A study of the hydrodynamics of spouted beds at temperatures ranging from room temperature to 580°C was carried out using a 0.156 m I.D. stainless steel conical-cylindrical half-column. Five narrowly sized fractions of Target sand with reciprocal mean diameters of 0.915 mm, 1.010 mm, 1.200 mm, 1.630 mm and 2.025 mm, and three orifices with internal diameters of 12.70 mm, 19.05 mm and 26.64 mm were used. The main purpose of the present work was to obtain a wide range of experimental data at high temperatures and compare the results with existing equations, to establish new correlations under different circumstances. Aspects studied included minimum spouting velocity, Ums, maximum spoutable bed height, Hm, and average spout diameter, Ds. It was found that the stability of spouting decreased with increasing temperature. The value of Ums increased with increasing temperature, especially for the large particles. The best of several empirical equations developed for Ums is one which uses the free-settling terminal velocity of the particles as a correlating parameter. The McNab - Bridgwater equation for Hm overpredicted Hm substantially at room temperatures and underpredicted Hm slightly at high temperatures. A similar equation with a slightly smaller value of Um/Umf than that recommended by McNab and Bridgwater gives better overall results. The Wu et al. non-dimensional equation for Ds, which explicitly includes the effect of gas density and gas viscosity, hence of gas temperature, gave better absolute prediction of the average spout diameter, Ds, than did the dimensional McNab equation, especially at elevated bed temperatures.

Thesis/Dissertation

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2008-12-17

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http://hdl.handle.net/2429/3011

Chemical and Biological Engineering

University of British Columbia

UBCV

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