Conical fluidized beds

Experiments were carried out in a conical shape gas fluidized bed (0.1 m-i.d. x 0.6 m-high) that made of a transparent acryl column with an apex angle of 20°. The details of the conical fluidized beds can be found elsewhere [3]. Air velocity (Ug = 0-1.4 m/s) were measured by a flowmeter. The particle used in this study was 1.0 mm glass beads with a density of 2,500... 

Variation of the individual velocities (U ,fd, U pf, Undr and Umb) with opening fraction of the distributor in the conical fluidized beds with the uniform distributor is shown in Fig. 6. With increasing Ug, Umb determined by the optical probe method is well agrees with Umu. However, with decreasing Ug, there is some discrepancy between Umb and Umfd since the optical probe in the lowest part is located 0.05 m above the distributor. 

Variation of bubble size, bubble frequency, and the standard deviation of -APbed with variation of Ug in the conical fluidized beds with a uniform gas distributor (Fopen = 3.87 %) is shown in Fig. 7. As can be seen, the standard deviation of - APbed and the bubble size increase with increasing Ug in the fully fluidized region. However, bubble frequency remains unchanged with variation of Ug that may imply the bubble size will increase as much as the volumetric gas flow increases. As shown, the bubble size dramatically increases with increasing Ug. Also, it is confirmed that the increase of standard deviation of -APbed is closely related to bubble size. 

Kurita, Y. and Sekiguchi, L, Effect of vortex orifice air distributor on granule growth in conical fluidized bed granulation with bottom entry spray, /. Ghent. Eng. Japan, 33 (2000) 57-66. 

Conical Fluidized Bed—Summary of Quantitative Relationships among Variables... 

The first type of conical fluidized bed operation for complete fluidization will be analyzed with respect to bed height and pressure drop. 

The range of fluid rates for various types of conical fluidized bed operation can therefore be summarized as follows ... 

F. Charting Conical Fluidized Bed Operation and Experimental Verification... 

Fig. 28. Conical fluidized bed 0.63-0.75 mm glass beads in water. Lines calculated points experimental. [After Kwauk, 1973.]... 

Institute of Chemical Metallurgy, Division III, Leaching in Conical Fluidized Beds, 1959-9 (1959). 

Wormsbecker, M. and Pugsley, T., Distributor induced hydrodynamics in a conical fluidized bed dryer. Drying TechnoL, 27, 797-804, 2009. 

Effect of Uniformity of Gas Distribution on Fluidization Characteristics in Conical Gas Fluidized Beds... 

Thermal pyrolysis for upgrading plastic wastes is one of the better methods for recycling plastics in terms of its perspectives for industrial implementation. The conical spouted bed reactor proposed in this paper may be a solution to the problems arising in fluidized beds handling sticky solids, as particle agglomeration phenomena, which can cause defluidization. In order to avoid defluidization, experiments have been carried out in batch mode in the temperature range of 450-600 °C. A good performance of the reactor is proven under the conditions of maximum particle stickiness. 

In the fluidized bed, the velocity of the particles is of a few cm s-1 and the critical thickness of the fused plastic is between 4 and 7 mm. A fact that should be taken into account is that, although gas velocity is increased, particle velocity hardly changes because most of the excess gas rises through the bed in the bubble phase. Nevertheless, in the conical spouted bed, particle velocity is increased by raising gas velocity up to the dilute spouted bed, in which bed voidage is uniform (between 0.9 and 0.99) and the particle descent velocity is almost equal to the ascent velocity [9]. 

In a later generation of fluidized bed classifiers the feed is poured onto the grid from above (Fig. 3c, d), so crushing is eliminated [9], Several prototypes of such fluidized bed classifiers with cylindrical or conical chambers of diameter 350-1700 mm and throughput of 0.5-10 t/h, were constructed for separation of sand, potassium chloride and ground phosphate particles with sizes from 50 to 1.5 mm [10], The recovery of coarse fraction was 75-92%. 

The inventory of solids, S, of a partially fluidized conical bed consists of two parts, one in the fluidized bed from level h to L, and the other in the fixed bed... 

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