Fluidized-bed systems for

In the reclamation of chemically or resin bonded sands, the system employed must be able to break the bond between the resin and sand and remove the fines that are generated. The systems most commonly employed are wet washing and scrubbing for silicate bonded sands, or dry scrubbing/attrition and thermal (rotary drum or fluidized bed) systems for resin bonded sands. 

Kunii, D. A Study of Particle-Circulating Fluidized Bed System for the Complete Utilization of Coal, Asahi Garasu Kogyo Gijustsu Shoreikai Kenkyu Hokoku, vol. 29, p. 235 (1976). 

Fluidized-bed adsorbers have several disadvantages. The continuous handling and transport of solids is expensive from an equipment standpoint fluidized-bed systems must be large to be economical. Solids handling also presents a potential for mechanical problems. Careful control is required to keep the adsorbent fluidized, while minimizing adsorbent loss with the gas-phase attrition of the adsorbent can be high, requiring substantial makeup. 

Figure 15. Flow sheet for SASOL fluidized bed system (45)...

Calcining. In the calcining process, the lime mud removed from the white liquor is burned to regenerate lime for use in the lime mixing step. The vast majority of mills use lime kilns for this process, although a few mills now use newer fluidized bed systems in which the reactants are suspended by upward-blowing air. 

Attrition in fluidized bed systems leads primarily to a loss of bed material since the cyclones, which are mostly used for the collection of entrained material, are not able to keep the attrition-produced debris inside the fluidized bed system. The material loss through the cyclone is, therefore, usually taken as the attrition rate. This means that among the attrition modes discussed in Sec. 2, namely fragmentation and abrasion, it is abrasion which is the attrition mode of interest for fluidized bed systems. 

Boija, R., and Banks, C. J., Kinetics of an Anaerobic Fluidized Bed System Used for the Purification of Fruit Processing Waste-Water, Chem. Eng. J., 54 B25 (1994)... 

Subsequently, simulations are performed for the air Paratherm solid fluidized bed system with solid particles of 0.08 cm in diameter and 0.896 g/cm3 in density. The solid particle density is very close to the liquid density (0.868 g/ cm3). The boundary condition for the gas phase is inflow and outflow for the bottom and the top walls, respectively. Particles are initially distributed in the liquid medium in which no flows for the liquid and particles are allowed through the bottom and top walls. Free slip boundary conditions are imposed on the four side walls. Specific simulation conditions for the particles are given as follows Case (b) 2,000 particles randomly placed in a 4 x 4 x 8 cm3 column Case (c) 8,000 particles randomly placed in a 4 x 4 x 8 cm3 column and Case (d) 8,000 particles randomly placed in the lower half of the 4x4x8 cm3 column. The solids volume fractions are 0.42, 1.68, and 3.35%, respectively for Cases (b), (c), and (d). 

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