Fluidized bed industries

Narvaez, I. Orio, A. Aznar, M. P. Corella, J., Biomass gasification with air in an atmospheric bubbling fluidized bed. Industrial and Engineering Chemistry Research 1996, 35(7), 2110-2120. 

Highley, J., and Kaye, W. G. Fluidized Bed Industrial Boiler and Furnaces, in Fluidized Beds Combustion and Applications (Howard, J. R., ed.), p. 127. Applied Science, London-New York (1983). 

Konttinen, J.T. Hot gas desulfurization with zinc titanate sorbents in a fluidized bed. Industrial Engineering Chemistry Research, 1997, 36, 2332. 

Mudde, R.F., Bruneau, P.R.P., and van der Hagen, T.H.J.J. (2005), Time-resolved y-densitometry imaging within fluidized beds, Industrial Engineering Chemistry Research, 44 6181-6187. 

Gaglia BN, Hall A. Comparison of bubbling and circulating fluidized bed industrial steam generation. Proceedings of the 1987 International Conference on Fluidized Bed Combustion, ASME, 1987, pp 18-25. 

The commercialization by Kureha Chemical Co. of Japan of a new, highly attrition-resistant, activated-carbon adsorbent as Beaded Activated Carbon (BAC) allowed development of a process employing fluidized-bed adsorption and moving-bed desorption for removal of volatile organic carbon compounds from air. The process has been marketed as GASTAK in Japan and as PURASIV HR (91) in the United States, and is now marketed as SOLD ACS by Daikin Industries, Ltd. 

Sasol produces synthetic fuels and chemicals from coal-derived synthesis gas. Two significant variations of this technology have been commercialized, and new process variations are continually under development. Sasol One used both the fixed-bed (Arge) process, operated at about 240°C, as weU as a circulating fluidized-bed (Synthol) system operating at 340°C. Each ET reactor type has a characteristic product distribution that includes coproducts isolated for use in the chemical industry. Paraffin wax is one of the principal coproducts of the low temperature Arge process. Alcohols, ketones, and lower paraffins are among the valuable coproducts obtained from the Synthol process. 

F/uidi ed-BedIncinerator. Fluidized-bed incinerators are employed in the paper and petroleum (qv) industries, in the processing of nuclear wastes, and the disposal of sewage sludge. These are quite versatile and can be used for disposal of soflds, Hquids, and gaseous combustible wastes. 

Dry dense medium (pneumatic fluidized-bed) separation has been used, but has not received wide attention by the industry. An area of promise for future development is the use of magnetically stabilized dense medium beds by using ferro or magnetic fluids (2,10). Laboratory and pilot-scale units such as Magstream are available. In this unit, material is fed into a rotating column of water-based magnetic fluid. Particles experience centtifugal forces and... 

Distributors in industrial units typically have large numbers of injection points of quite diverse design characteristics, some of which are depicted in Eigure 16 for fluidized-bed appHcations. Flow variations through these parallel paths can lead to poor flow distributions within a reactor, thus reducing product yields and selectivity. In some circumstances, undesirable side products can foul portions of the distributor and further upset flow patterns. Where this is important, or where the possibiHties and consequences are insufficiently understood and independent means caimot be employed to assure adequate distribution, the pilot plant must be sized to accommodate such a distributor. Spacing should be comparable to those distributors that are anticipated to be... 

Industrial Uses. Large industrial faciUties, particularly those using cyclone boilers or fluidized-bed boilers, are potential markets. In addition, several vendors of small- and medium-sized industrial energy and steam faciUties are marketing units capable of using I DE. As the availabiUty of I DE expands with new producers entering the market, it is hoped that the industrial use of I DE will also expand (7). 

Some of the advantages of fluidized beds include flexibiUty in fuel use, easy removal of SO2, reduced NO production due to relatively low combustion temperatures, simplified operation due to reduced slagging, and finally lower costs in meeting environmental regulations compared to the conventional coal burning technologies. Consequently, fluidized-bed combustors are currently under intensive development and industrial size units (up to 150 MW) are commercially available (Fig. 10). 

Activated alumina and phosphoric acid on a suitable support have become the choices for an iadustrial process. Ziac oxide with alumina has also been claimed to be a good catalyst. The actual mechanism of dehydration is not known. In iadustrial production, the ethylene yield is 94 to 99% of the theoretical value depending on the processiag scheme. Traces of aldehyde, acids, higher hydrocarbons, and carbon oxides, as well as water, have to be removed. Fixed-bed processes developed at the beginning of this century have been commercialized in many countries, and small-scale industries are still in operation in Brazil and India. New fluid-bed processes have been developed to reduce the plant investment and operating costs (102,103). Commercially available processes include the Lummus processes (fixed and fluidized-bed processes), Halcon/Scientific Design process, NIKK/JGC process, and the Petrobras process. In all these processes, typical ethylene yield is between 94 and 99%. 

In the chemical engineering domain, neural nets have been appHed to a variety of problems. Examples include diagnosis (66,67), process modeling (68,69), process control (70,71), and data interpretation (72,73). Industrial appHcation areas include distillation column operation (74), fluidized-bed combustion (75), petroleum refining (76), and composites manufacture (77). 

Contactive (Direct) Heat Transfer Contactive heat-transfer equipment is so constructed that the particulate burden in solid phase is directly exposed to and permeated by the heating or cooling medium (Sec. 20). The carrier may either heat or cool the solids. A large amount of the industrial heat processing of sohds is effected by this mechanism. Physically, these can be classified into packed beds and various degrees of agitated beds from dilute to dense fluidized beds. 

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. 

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. 

Fluidized-Bed Combustion The principles of gas-solid fluidization and their application to the chemical process industry are treated in Sec tion 17. Their general application to combustion is reviewed briefly here, and their more specific application to fluidized-bed boilers is discussed later in this section. 

Miscellaneous Systems Many other systems have been proposed for transferring heat regeneratively, including the use of high-temperature hquids and fluidized beds for direct contact with gases, but other problems which hmit industrial application are encountered. These svstems are covered by methods described in Secs. 11 and 12 of this handbook. 

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