Fluidized bed reactor for

Fig. 14. Fluidized-bed reactor for SASOL I (M. W. Kellogg) having process conditions of an alkaline, reduced high grade magnetite, reduction degree 95% ...

The value for is conservatively interpreted as the particle diameter. This is a perfectly feasible size for use in a laboratory reactor. Due to pressure-drop limitations, it is too small for a full-scale packed bed. However, even smaller catalyst particles, dp 50 yum, are used in fluidized-bed reactors. For such small particles we can assume rj=l, even for the 3-nm pore diameters found in some cracking catalysts. 

Hydrodynamics, Heat and Mass Transfer in Inverse and Circulating Three-Phase Fluidized-Bed Reactors for WasteWater Treatment... 

To provide the pr equisite knowledge for designing the three-phase fluidized-bed reactors with new modes, the hydrodynamics such as phase holdup, mixing and bubble properties and heat and mass transfer characteristics in the reactors have to be determined. Thus, in this study, the hydrodynamics and heat and mass transfer characteristics in the inverse and circulating three-phase fluidized-bed reactors for wastewater treatment in the present and previous studies have been summarized. Correlations for the hydrod3aiamics as well as mass and heat transfer coefficients are proposed. The areas wherein future research should be undertaken to improve... 

Three different types of furnaces are generally in use for calcination. The shaft furnace is considered to be the most suited for calcining coarse limestone. Furnaces of the rotary kiln type are used for handling materials of mixed particle sizes and lumps which disintegrate during the process. Calcination can be carried out in a fluidized bed-reactor for materials of small and uniform particle size. These furnaces are usually fired with gas, oil or coke in some cases electric heating is resorted to. 

Green, M., Schnitzer, M., and Tarre, S., Kinetics of a Fluidized-Bed Reactor for Ground-Water Denitrification, / / / /. Microbiol. Biotechnol., 43 188 (1995)... 

Qureshi, N., and Maddox, I. S., A Mathematical Model of a Fluidized Bed Reactor for the Continuous Production of Solvents by Immobilized Clostridium acetobutylicum, J. Chem. Tech. Biotechnol., 48 369 (1990)... 

Webb, O. F., Davison, B. H., Scott, T. C., and Scott, C. D., Design and Demonstration of an Immobilized-Cell Fluidized-Bed Reactor for the Efficient Production of Ethanol, Appl. Biochem. Biotechnol., 51/52 559 (1995)... 

Obviously, these two items are not strictly separated in contrast, the most fruitful approach is when they are simultaneously followed, so that they can mutually benefit from each other. In this chapter, we want to focus on the use of simulation methods as a design tool for gas-fluidized bed reactors, for which we consider gas-solid flows at four distinctive levels of modeling. However, before discussing the multilevel scheme, it is useful to first briefly consider the numerical modeling of the gas and solid phase separately. 

Figure 117 Fluidized-bed reactor for roasting zinc concentrate (after Themelis and Freeman, 1983)...

A fluidized-bed reactor for a solid-catalyzed gas-phase reaction (of A) operates with relatively small catalyst particles. Based on the information given below, calculate the follow-... 

When we are interested in the reproducible preparation of metal-supported catalysts it is also necessary to integrate the mesoscopic scale. Indeed, the deposit needs to be homogeneous, with particles anchored not only on all the support grains but also in their porosity. The use of CVD-fluidized bed reactors, for which we have gained some experience [85, 86], is one of the most elegant ways to master a process that fulfils these requirements under relatively mild conditions. 

Santos, J.C., Silva, S.S., Mussatto, S.I., Carvalho, W. and Cunha, M.A.A., Immobilized cells cultivated in semi-continuous mode in a fluidized bed reactor for xylitol production from sugarcane bagasse, World. Microbiol. Biotech., 21 (2005) 531-535. 

Calculate the conversion in a fluidized bed reactor for the catalytic hydrogenation of nitrobenzene to analine. 

The fluidized bed reactor has been used by several researchers to study the kinetics of chemical weathering (Holdren and Speyer, 1985, 1987 Chou and Wollast, 1985). One of the advantages in using the fluidized bed reactors for studies of this type is that there are no strong concentration gradients in the aqueous and solid phases. Additionally, the concentration of the dissolved species can be maintained at levels well below saturation with respect to possible precipitates. This means, for example, that one could study mineral dissolution exclusively without secondary precipita-... 

The attrition of solid particles is an unavoidable consequence of the intensive solids motion resulting from the presence of bubbles in the fluidized bed. The attrition problem is especially critical in processes where the bed material needs to remain unaltered for the longest possible time, as in fluidized-bed reactors for heterogeneous catalytic gas-phase reactions. Catalyst attrition is important in the economics of such processes and may even become the critical factor. 

In this section the industrial uses of fluidized-bed reactors for heterogeneous catalytic gas-phase reactions and the polymerization of alkenes are presented. The most important applications are listed and a few typical examples are analyzed in more detail. Complete descriptions of industrial uses of the fluidized-bed reactor can also be found in Refs 2, 6, 12 and 13. 

The crucial factor in the successful use of the fluidized-bed reactor for the synthesis of acrylonitrile by the ammoxidation of propenc (Sohio process) was... 

Reaction kinetics may be determined for a fixed-bed reactor, provided measurements are performed under conditions comparable to those that prevail in the fluidized-bed reactor (for example the same solids composition and particle-size distribution, and the same activity state) [98] However, the kinetic parameters can also be determined directly by measurements in a bench-scale fluidized-bed apparatus [99]... 

Cooper, P, F., The Two Fluidized Bed Reactor for Wastewater Treatment, Chap. 11 in Process Engineering Aspects of Immobilized Cell Systems, pp. 179-204. Instn. Chem. Engrs. (London), 1986. 

The hydrogenation of nitrobenzenes to anilines is carried out in a liquid phase or in a vapor phase, in either a fixed-bed or a fluidized-bed reactor. For vapor-phase processes, copper-based catalysts97 and sulfided nickel98 are among those most frequently used. For liquid-phase processes, supported nickel99 and Raney Ni100 as well as supported palladium101 are the catalysts most commonly employed. 

In suspension reactors as well as in fluidized bed reactors for the free-falling velocity of a single particle has to be used. The free falling velocity of spheres can be found according to the following derivation. In the steady state the weight of the particle in the fluid is equal to the resistance to flow ... 

Arpalahti, Olli, Recirculating fluidized-bed reactor for the removal of particulate material from flue gases," Finland FI 77165 B, 881031, FI 86244 (860120), 11 pp. (1988). 

Cheng, D. A Study on the Fluidized Bed Reactor for Manufacture of Butadiene from Butene (in Chinese), The Proceeding of 5th National Conference on Fluidization, pp. 353-356 (1990). 

Kaczmarzyk, Grzegorz and Sciazko, Marek. Coal pyrolysis in a circulating fluidized-bed reactor for hybrid gas-steam power plants, Koks, Smola, Gas, vol. 35, No. 8, pp. 175-84 (1990). 

Simulation of a Fluidized Bed Reactor for the Production of Maleic Anhydride... 

In contrast to this, the residence time of the products in a fluidized bed lies between 1 and 5 s [20]. Buekens [21] studied the influence of the residence times in technical fluidized-bed processes. One of the main advantages in using a fluidized bed reactor for depolymerization is that it involves no contamination of organometallic compounds in the products and less environmental problems [1]. Therefore, companies are looking to use fluidized-bed processes especially for filled PMMA. The filler will contaminate the molten metal bath while in a fluidized bed the often expensive fillers can be recovered. 

Figure 25.18 Fluidized-bed reactor for hydrolysis of PET [44]. (Reprinted from Polymer Degradation and Stability, Vol. 85, G. Grause etal., pp. 571, 2004, with permission from Elseveir)...

Patil, C.S., van Sint Annaland, M., and Kuipers, J.A.M. Design of a novel autothermal membrane-assisted fluidized-bed reactor for the production of ultrapure hydrogen from methane. Industrial Engineering Chemistry Research, 2005, 44 (25), 9502. 

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