Fluidization applications

Fluidization Regime. As for traditional fluidization applications, the fluidization regime—dispersed bubble, coalesced bubble, or slugging—in which a three-phase fluidized bioreactor operates depends strongly on the system parameters and operating conditions. Generally, desirable fluidization is considered to be characterized by stable operation with uniform phase holdups, typical of the dispersed bubble regime. It would be useful to be able to predict what conditions will produce such behavior. 

Baskakov, A. P., Vitt, O. K., Kirakosyan, V. A., Maskaev, V. K. and Filippovsky, N. F. (1974). Investigation of Heat Transfer Coefficient Pulsations and of the Mechanism of Heat Transfer from a Surface Immersed into a Fluidized Bed. Proceedings of International Symposium on Fluidization Applications. Toulouse Cepadues-Editions. 

Kohno, T., and Shimano, S. Application of Fluidization. Application of Optimal Control to Circulating Fluidized-Bed Calciner for Alumina, Kagaku Kogaku, vol. 49, No. S, p. 3S2... 

For use in fluidization applications, starting from a sieve analysis the mean size of the powder is often calculated from... 

Arnaldos J, Kozanoglu B, Casal J. Vacuum fluidization application to dr5nng. In Fan LS, Knowlton TM, eds. Fluidization IX, Durango, Colorado. New York Engineering Foundation, 1998, pp 709-716. 

Fig. 16. Typical distributor grid designs for fluidized-bed applications (a) porous plate, (b) cone, (c) perforated plate, (d) downward dish, (e) upward dish,...

Equation (11-48) is applicable to burdens in the solid, liquid, or gaseous phase, either static or in laminar motion it is apphcable to solidification equipment and to divided-solids equipment such as metal belts, moving trays, stationaiy vertical tubes, and stationaiy-shell fluidizers. 

Spouted Beds The spoutedT)ed technique was developed primarily for sohds which are too coarse to be handled in fluidized beds. Although their applications overlap, the methods of gas-sohds mixing... 

Vibrofluidizatlon It is possible to fluidize a bed mechanically by imposing vibration to throw the particles upward cychcaUy. This enables the bed to operate with either no gas upward velocity or reduced gas flow. Entrainment can also be greatly reduced compared to unaided fluidization. The technique is used commercially in drying and other applications [Mujumdar and Erdesz, Drying Tech., 6, 255-274 (1988)], and chemical reaction applications are possible. See Sec. 12 for more on diying applications of vibrofluidization. 

When heavier refractories are required because of operating conditions, insulating brick is installed next to the shell and firebrick is installed to protect the insulating brick. Industrial experience in many fields of application has demonstrated that such a hning will success-billy withstand the abrasive conditions for many years without replacement. Most serious refractory wear occurs with coarse particles at high gas velocities and is usually most pronounced near the operating level of the fluidized bed. 

There are many uses of fluidized beds. A number of applications have become commercial successes others are in the pilot-plant stage, and others in bench-scale stage. Generally, the fluidized bed is used for gas-solids contac ting however, in some instances the presence of the gas or sohd is used only to provide a fluidized bed to accomplish the end result. Uses or special (maracteristics follow ... 

Fluidized-bed opposed-jet mills Hosokawa Micron Powder Systems Div.) differ from the Majac mill in that powder is not fed into the jets, but the jets impinge into a chamber mich contains suspended powder. The powder is entrained into the jets. This ehminates wear on the nozzles, and reduces contamination. Otherwise, construction and appheations are similar to the Majac mill. The fluidized-bed level is maintained a few inches above the jets. The Fluidized-bed mill is available in 13 sizes with air volumes ranging from. 50 to 11,000 mVh. One application is for toner grinding. 

TABLE 25-46 Full-Scale Commercial Applications of Fluidized Bed Process... 

The anaerobic filter, UASB, and fluidized bed reac tors have all been used for anaerobic treatment of industrial wastes, as each is especially suited for use in anaerobic treatment. Table 25-44 presents results from these applications. 

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