Fluidized beds, uses

Carbochlorination. Milled zircon and coke are reacted with hot chlorine gas in a fluidized bed using chlorine as the fluidizing medium ... 

Viswanathan et al. (V6) measured gas holdup in fluidized beds of quartz particles of 0.649- and 0.928-mm mean diameter and glass beads of 4-mm diameter. The fluid media were air and water. Holdup measurements were also carried out for air-water systems free of solids in order to evaluate the influence of the solid particles. It was found that the gas holdup of a bed of 4-mm particles was higher than that of a solids-free system, whereas the gas holdup in a bed of 0.649- or 0.928-mm particles was lower than that of a solids-free system. An attempt was made to correlate the gas holdup data for gas-liquid fluidized beds using a mathematical model for two-phase gas-liquid systems proposed by Bankoff (B4). 

Assuming the same concentration driving force in both fixed and fluidized beds, use... 

Daw, C. S., and Harlow, J. S., Characteristics of Voidage and Pressure Signals from Fluidized Beds using Deterministic Chaos Theory, Proc. 11th Int. Conf. FluidizedBedComb., 2 777 (1991)... 

Figure 2. Spouted and fluidized beds used in coating operations.

Wu, K. Y. A., and Wisecarver, K. D., Biological Phenol Degradation in a Countercurrent Three-Phase Fluidized Bed Using a Novel Cell Immobilization Technique, AIChE Symp. Series, 86(276) 113 (1989)... 

KK [Kunugi and Kunii] A process for cracking crude petroleum or heavy oil in a fluidized bed, using coke as the heat carrier. Developed originally by Kunigi and Kunii, subsequently improved by the Japanese Agency of Industrial Science with five Japanese companies. Piloted between 1979 and 1982. 

Despite the importance of fluidized bed granulafion wifhin the food indusfry, fhere is relafively little published literature on the operation of fluidized beds used for agglomeration, instantising, coating or encapsulation of food materials and consequently very little... 

Monoethylaniline can also be produced in the vapor phase in a fluidized bed using natural bauxite as the solid catalyst. The elementary reactions are shown in the previous problem. Using an equimolar feed of aniline and ethanol, the fluidized bed produces 3 parts monoethylaniline to 2 parts diethylaniline for a 40% conversion of aniline. Assuming mixed flow of gas in the fluidized bed, find k2lk and the concentration ratio of reactants and products at the exit of the reactor. 

Ergun (45) presents results which very strongly support mechanism B. Experiments were conducted in a fluidized bed using three different types of carbon (Ceylon graphite, activated carbon, and activated graphite). These samples had a considerable range of mineral content (from a trace to 0.5 %) and although not reported, it is certain that they also had a wide... 

If chemical engineering needed such a locus classicus, it could well be the fluidized bed. Used for heat transfer and mass transfer, separations and... 

In these devices classification occurs in the space over a fluidized bed from which fine particles are carried away with the air stream. The air velocity must essentially exceed the maximal fluidization velocity of fine fraction. These classifiers operate on the gravitational counterflow separation principle with fluidized bed used to increase particles residence time in the separator. Coarse particles can move horizontally across the bed to the exit, which is another advantage of this device. 

Schnitzlein, M.G. and Weinstein, H. (1988). Flow Characterization in High-Velocity Fluidized Beds Using Pressure Fluctuations. Chem. Eng. Sci., 43,2605. 

Equation (12.71) provides a means to quantify kf on the basis of experimentally measured inlet and outlet concentrations of species A in the bed under low gas velocity conditions. Wen and Fane (1982) proposed the following empirical correlations for overall mass transfer coefficients in gas-solid fluidized beds, using the experimental data of Kato et al. (1970) based on Eq. (12.71) ... 

Coking of Equilibrium Catalyst. A 200 g portion of equilibrium USY octane catalyst (Catalyst A) was precoked in a fluidized bed using a stream of isobutene diluted with nitrogen gas (400 ml/min) at 510°C. The catalyst was held in a 2-inch diameter quartz tube while 27.8 g of isobutene gas was passed upflow through it at atmospheric pressure over a period of 25 minutes. 

Wang, F., Marashdeh, Q., Warsito, W., and Fan, L.-S., Imaging gas/solid jet penetration in a gas-solid fluidized bed using electrical capacitance volume tomography, AIChE Annual Meeting, Philadelphia, PA, USA, 16-21 November, Section 03B01 (2008). 

Various configurations have been developed for muitistaging of fluidized beds using the pneumatically controlled downcomer, as shown in Fig. 38. Figure 38A shows the fundamental concept of multistaging of fluidized beds, with a downcomer between two adjacent beds, each downcomer being supplied with a separate stream of control gas. Consequently, there are as many control gas streams as there are stages. 

Fig. 38. Configurations for multistage fluidized beds using the pneumatically controlled downcomer. [After Kwauk, 1974 Liu and Kwauk, 1980 Liu et al., 1981.]...

In some situations the dynamics of the cooling system may be such that effective temperature control cannot be accomplished by manipulation of the coolant side. This could be the situation for fluidized beds using air coolers to cool the recirculating gases or for jacketed CSTRs with thick reactor walls. The solution to this problem is to balance the rate of heat generation with the net rate of removal by adjusting a reactant concentration or the catalyst flow. Such a scheme is shown in Fig. 4.24. 

Batchelor (1988) developed a force balance equation for the solid phase in fluidized beds using the ensemble average method. With the help of the resulting equation and the theory of linear stability the following criterion was obtained by Ham et al. (1990) ... 

Table 17.2 Pyrolysis of polyethylene (PE), used syringes, and tires by the Hamburg Pyrolysis process in a fluidized-bed using pyrolysis gas as fluidizing gas. Products iu wt%...

Spouted-bed circulation rates obtained by Chatterjee are considerably higher than those reported for fluidized beds using a similar technique (Fig. 22). This comparison supports Chatterjee s view that spouting is a suitable operation for solids-blending processes. 

---