Continuous fluidized bed reactor

Fluidized bed dehydrogenation technology is more prevalent in the former Soviet Union. A continuous fluidized-bed reactor system is used with a... 

Matsui, L Kojimas, T. Furusawa, T. Kunii, D. Gasification of coal char in a continuous fluidized bed reactor. In Fluidization Kunii, D., Toei, R.,... 

A 10-in. diameter continuous fluidized-bed reactor system is being operated to produce nonagglomerating coal from high volatile bituminous coal by mild surface oxidation. Minimum pretreatment is defined by acceptability of the coal as a feed to the hydro gasifier. This corresponds to 24-26% volatile matter in the pretreated coal. The following operating variables, in the order of importance, contribute to satisfactory pretreatment—reaction temperature of 725°-750°F., oxygen reacted coal feed ratio of 1.0 1.5 std. cu. ft./lb.9 and a coal residence time of 1-2 hours. 

Coal Residence Time. Because the oxidation rate is fast, there is essentially no residence time required for chemical reaction. In a plug flow reactor, coal feed rate would depend only on the oxygen input rate and the unit oxygen consumption. Moreover, if gas distribution is uniform, the oxidation would be uniform. In a continuous fluidized-bed reactor, however, residence time must be long enough to minimize the effect of the short-circuiting of untreated feed into the product. The... 

Matsui, I., T. Kojima, T. Furusawa and D. Kunii. Gasification of Coal Char by Steam in a Continuous Fluidized Bed Reactor, in Fluidization, ed. D. Kunii and R. Toei, pp.655-662. (New York, Engineering Foundation, 1984). 

An active immobilized form of )3-D-fructofuranosidase has been prepared by adsorption onto DEAE-cellulose. The product was used in a continuous fluidized bed reactor. 

Active immobilized enzyme possessing haemagglutinating activity Active immobilized enzyme kinetic studies and the hydrolysis of dextrans Active immobilized enzyme for a continuous fluidized-bed reactor... 

Active immobilized enzyme comparison of the kinetic properties of the two immobilized forms Active immobilized enzyme used in a continuous fluidized-bed reactor Active immobilized enzyme for the treatment of cheese whey Active immobilized en me that permits free approach by low-molecular-weight substrates... 

The second process is a continuous fluidized bed reactor. In an Idemitsu Petrochemical patent [7], a helical ribbon mixer is adopted. High power consumption and high SPS conversion are important to avoid adhesions. In this process, the polymerization heat is removed by the evaporation heat of styrene and by the jacket coolant. 

Figure 12.4 shows the flow diagram of the continuous fluidized bed reactor process. 

Figure 12.4 Flow diagram of a continuous fluidized bed reactor process. V-300 fluidized bed reactor E-310 1. Fleat exchanger V-310 1. Surge tank E-320 2. Heat exchanger V-320 2. Surge tank C-320 vacuum pump.

Figure 2.8 A fluidized-bed reactor allows the catalyst to be continuously withdrawn and regenerated as with the refinery catalytic cracker.

By contrast, if the reactor is continuous well-mixed, then the reactor is isothermal. This behavior is typical of stirred tanks used for liquid-phase reactions or fluidized-bed reactors used for gas-phase reactions. The mixing causes the temperature in the reactor to be effectively uniform. 

The use of a fluidized-bed reactor is possible only when the reactants are essentiaUy in the gaseous phase. Eluidized-beds are not suitable for middle distiUate synthesis, where a heavy wax is formed. Eor gasoline synthesis processes like the MobU MTG process and the Synthol process, such reactors are especiaUy suitable when frequent or continuous regeneration of the catalyst is required. Slurry reactors and ebuUiating-bed reactors comprising a three-phase system with very fine catalyst are, in principle, suitable for middle distiUate and wax synthesis, but have not been appHed on a commercial scale. 

FIG. 23-24 Reactors with moving catalysts, a) Transport fluidized type for the Sasol Fischer-Tropsch process, nonregenerating, (h) Esso type of stable fluidized bed reactor/regeuerator for cracldug petroleum oils, (c) UOP reformer with moving bed of platinum catalyst and continuous regeneration of a controlled quantity of catalyst, (d) Flow distribution in a fluidized bed the catalyst rains through the bubbles. 

Reactors may be operated batchwise or continuously, e.g. in tubular, tubes in shell (with or without internal catalyst beds), continuous stirred tank or fluidized bed reactors. Continuous reactors generally offer the advantage of low materials inventory and reduced variation of operating parameters. Recycle of reactants, products or of diluent is often used with continuous reactors, possibly in conjunction with an external heat exchanger. 

Describe the advantages and disadvantages of the following reactor types with reference to heat and mass transfer. For each reactor discuss one reaction for which it may be appropriate to use that reactor, (a) fluidized bed reactor, (b) A continuous counter-current flow reactor, (c) A monolith reactor. 

Adsorption and photocatalytic oxidation of TCE with Ti02-coated activated carbon was also carried out in a cylindrical continuous flow fluidized bed reactor with 65cm height and 68cm inside diameter (Figure 1). 

If deactivation of the catalyst is very short, then moving-or fluidized-bed reactors are required so that the catalyst can be withdrawn continuously, regenerated and returned to... 

The primary advantage of fluidized bed reactors, however, is that they permit continuous, automatically controlled operations using reactant-catalyst systems that require catalyst regeneration at very frequent intervals. Fluidized bed operation permits one to easily add or remove the catalyst from the reactor or the regenerator. Regeneration can be accomplished by any convenient procedure, but the... 

Bravo, P., and Gonzalez, G., Continuous Ethanol Fermentation by Immobilized Yeast Cells in a Fluidized-Bed Reactor, J. Chem. Tech. Biotechnol., 52 127 (1991)... 

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