Plasma fluidized bed

The experimental results obtained from the plasma fluidized-bed cracking device were in an agreement with the theoretical predictions taking into account the role of reactive species produced by the plasma. 

Nikravech, M. et al., Plasma-fluidized bed hydrocracking process of heavy hydrocarbons, Proc. 9th Int. Symp. on Plasma Chemistry, Pugnochiuso, Italy, 209,1989. 

Carbothermic Reduction of Iron from Iron Titanium Oxide Concentrates in a Thermal Plasma Fluidized Bed... 

A schematic of the plasma-metallurgical reactor based on the apphcation of a plasma fluidized bed is shown in Fig. 7-20. The reduction process is due to both carbon mixed with FeO Ti02 and hydrogen used as a gas energy carrier in the discharge. (Juasi-thermal plasma is generated in the reduction reactor by means of a spark discharge between two electrodes. 

The conversionfrom tricalcium phosphate to elementary phosphoras was close to 100%. The process was performed in a plasma fluidized bed supported by argon flow at 1030-1200°C. Mosse and Pechkovsky (1973) applied CH4 as a plasma gas and reduction agent for processing tricalcium phosphate. The reaction was conducted in an atmospheric-pressure CH4 plasma jet at 3000 000 K, the residence time was 0.01-0.05 s, and the phosphate-to-CH4 ratio was 1 10. The conversion degree from Cas (P04)2 to elementary phosphoras was up to 75%. Gas-phase by-products included acetylene and other hydrocarbons, PH3, CO, and CO2 solid-phase by-products included mostly calcium carbide and phosphide. Another major compound of natural phosphates is fluoroapatite, Ca5p(P04)3. Practical applications... 

Quede, A. Cardoso, J. Le Bras, M. Delobel, R. Goudmand, P. Dessaux, O. Jama, C. Thermal stability and flammability studies of coated polymer powders using a plasma fluidized bed process. J. Mater. Sci. 2002, 37(7), 1395. 

Heat transfer between gas and sohds is exceedingly hard to measure because it is so rapid. Although the coefficient is low, the available surface area and the relative specific heat of solid to gas are so large that temperature equilibration occurs almost instantaneously. Experiments on injection of argon plasmas into fluidized beds have shown quenching rates of up to fifty million degrees Kelvin per second. Thus, in a properly designed bed, gas to solids heat transfer is not normally a matter of concern. 

The Subpart O standards apply to units that treat or destroy hazardous waste and which meet the definition of an incinerator. An incinerator is any enclosed device that uses controlled flame combustion and does not meet the criteria for classification as a boiler, sludge dryer, carbon regeneration unit, or industrial furnace. Typical incinerators1 2 3 include rotary kilns, liquid injectors, fixed hearth units, and fluidized bed incinerators (Table 23.1). The definition of an incinerator also includes units that meet the definition of an infrared incinerator or plasma arc incinerator. An infrared incinerator is any enclosed device that uses electric-powered resistance as a source of heat and which is not listed as an industrial furnace. A plasma arc incinerator is any enclosed device that uses a high-intensity electrical discharge as a source of heat and which is not listed as an industrial furnace. 

One of the important aspects is the surface exposure of powder substrates during the plasma modification process. For this, the aggregations of the powders should be destroyed. A fluidized bed is a way to expose all the powder particles to plasma. In this case, the powder is placed on a porous plate in the reactor, which... 

The adhesion between phases and the dispersion state seem to play a very important role. To improve wetting behavior, dispersion, and adhesion by grafting reactions, a plasma treatment (02/N2/NH3) of the TP powders can be performed in a fluidized bed (Lennon et al., 2000a). 

Thermal treatment processes use energy to destroy or decontaminate waste. These technologies include low or high energy thermal processes. Several types of thermal processes include flame combustion, fluidized bed combustion, infrared incineration, pyrolysis and plasma heat systems. 

Morooka, S Kawamura, H., Yan, S., Okubo, T., and Kusakabe, K. Surface Modification of Milled Carbon Fibre by Low-Temperature Oxygen Plasma in a Fast Fluidized Bed, in Circulating Fluidized Bed Technology III (Basu, P., Horio, M., and Hasatani, M eds.), pp. 456-464. Pergamon Press, Oxford (1991). 

As shown in Fig. (8), fluorination reactions of polyethylene powders in the fluidized bed were slower compared to those of films in the plasma. This may be related to the greater surface area involved in the treatment of powders ( 0.15 m /g for powder compared to 0.03 m /g for film). Further, for treatment of powders, the overall extent of fluorination is lower compared to that of films - 52% F as opposed to 60% for films (Fig. 8). This is also supported by the C, spectra (Fig. 9) in which residual... 

Microwave-assisted fabrication of ceramic coatings on fibers and powders can be done at intermediate temperatures. For example, at temperatures of about 800-900° C, carbon fibers have been coated with thin TiN layers using a microwave plasma-assisted fluidized bed with the precursor vapor (TiCU in this case) being introduced into the reactor by the fluidizing gas. ... 

Methods of filler pretreatment if coupling agent is required, filler is usually pretreated before incorporation fluidized bed glass fiber impregnation in sheet forming surface modification of chalk and carbon fiber by acetylene gas plasma stearic and oleic acids phosphate coating for talc "... 

Surface Modification of Polymer Powders by a Far Cold Remote Nitrogen Plasma in Fluidized Bed... 

To treat thermo-sensitive powders, some authors [1-2] have coupled two technologies a cold plasma to generate active species in a gas and a fluidized bed to promote the gas-particles contact. Nitrogen cold remote plasmas allow grafting nitrogen on surface and then for instance, to increase the hydrophilicity of polymer powders [1-3]. 

In the present work, the influence of the fluidization ratio and of the run duration has been investigated for the treatment by a cold remote nitrogen plasma of PE powders in a fluidized bed reactor. The fixed bed height to reactor diameter ratio is 1 which corresponds to the definition of a fluidized bed. 

Plasma reduction of metals from their oxides can also be carried out in fluidized beds. Such technology was applied, in particular, for the caibothermic reduction of iron from FeO Ti02 (Borodulia, 1973) ... 

Plasma is effective in the fabrication of nanocomposites, such as nanoparticles composed of one material and covered by a nanolayer of another. Relevant examples include, in particular, carbon-coated magnetic metal particles produced in thermal arc plasma (McHenry et al., 1994), as well as polymer-coated nanoparticles with improved adhesion, corrosion resistance, and surface passivation produced in RF plasma in a fluidized bed (Shi et al.,... 

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