Maldistribution in Fluidized Beds

• Published in: Industrial & engineering chemistry research 2002-11, Vol.41 (23), p.5878-5889
• Main Authors: Thorpe, Rex B, Davidson, John F, Pollitt, Michael, Smith, Jason
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical engineering; Exact sciences and technology; Fluidization
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie0203173

Experiments on maldistribution were performed using a 289 mm diameter air−sand fluidized bed with a multiorifice distributor. The minimum superficial gas velocity (U m) required to eliminate maldistribution was measured; the results were combined with those in the literature and used to evaluate the following rules for maldistribution:  (1) the pressure drop ratio method, that is, a specified ratio of distributor pressure drop to bed pressure drop, R, as recommended by Perry et al., (2) the theory of Fakhimi and Harrison, based on a pressure balance for the gas passing through active and inactive gas injection points at the distributor, and (3) the theory of Yue and Kolaczkowski, a modification of Fakhimi and Harrison's theory. The data cover a variety of bed sizes and shapes including the industrially sized beds of Whitehead and Dent, who used tuyere distributors. The best agreement was found with the theory of Fakhimi and Harrison, which gives a simple formula for predicting U m if combined with reliable predictions , for the height of the entry zone, h. The average error in predicting U m this way was 18%, and the largest error was a factor of 2. The traditional method, using a specified R, shows a largest error of a factor of 6 in U m if the best value of R is used.