Furnaces fluidized bed

New furnace concepts in evolutionary stages include fluidized-bed furnaces (25), coal gasification furnaces (26), and MHD furnaces (27,28). Of these technologies, fluidized-bed combustion has reached commercial-scale operations (Fig. 11). 

Calcium oxide (lime) Rotary kilns, vertical and shaft kilns, fluidized bed furnaces Particulate matter Cyclones plus secondary collectors (baghouse, ESP, wet scrubbers, granular bed filters, wet cyclones)... 

Conventional thermal treatment methods, such as rotary kiln, rotary hearth furnace, or fluidized-bed furnace, are used for waste pyrolysis. Molten salt process may also be used for waste pyrolysis. 

Lotze, J., and Wargalla, G. Characteristic Data and Utilization Possibilities of Ash from a Circulating Fluidized Bed Furnace. Part 1 Process Engineering and Characteristics, Zem.-Kalk-Gips, Ed. B, 38(5), 239 (1985). 

SO2 is also obtained commercially from metal sulfide ores by roasting in fluidized bed furnaces (equation 11). The reaction is carried out at 650 1100 °C, with the resultant SO2 being filtered electrostatically to remove ash and then freed of AS2O3 impurities before being used in the preparation of SO3. 

This reaction is currently preferably carried out in multiple hearth roasters, rotary tube furnaces or fluidized bed furnaces. 

The aluminum hydroxide-depleted alkali is, after separating off the aluminum hydroxide, partially evaporated and then returned to the bauxite digestion. The aluminum hydroxide obtained is processed mainly by calcination in rotating tube furnaces or in, energy-saving (VAW-Lurgi process), fluidized bed furnaces at 1200 to 1300°C to aluminum oxide (a-Al203). A small quantity of the aluminum hydroxide is carefully dried and used as such. 

This diluted aqueous uranyl nitrate solution is evaporated to uranyl nitrate hexahydrate, U02(N03)2 6H2O, which is then calcined to uranium(VI) oxide in a fluidized bed furnace ... 

The temperature must not exceed 400°C, to prevent the formation of U3O8. The nitrous gases produced are processed to nitrie aeid, whieh is recycled. The subsequent reduction of uranium(VI) oxide to uranium(IV) oxide with hydrogen at 500°C also proceeds in the fluidized bed furnace. 

The soda-AQ proeess ean use the same ehemieal recovery system as for kraft pulping but is teehnieally well suited to a simpler, more compact system known as DARS (direet alkali reeovery system), whieh has been explored on the pilot plant seale. Here ferrie oxide is added to the blaek liquor in a fluidized bed furnace. The residue of sodium ferrite partieles is removed and on leaching under controlled eonditions regenerates sodium hydroxide and ferrie oxide ... 

Fluidized bed combustion. In the temperature range 820 to 870°C, limestone reacts with SO2 and air to give calcium sulfate rather than sulfite, and this product can be safely disposed of or utilized, for example, as roadbed cement. Fennelly describes a two-stage fluidized bed furnace (Fig. 8.2) in which coal fluidized in an airstream is burned at 1100 to 1300°C (the temperature at which combustion is most efficient) around the boiler tubes, giving highly efficient heat transfer without formation of hot spots. The gases then pass to the... 

Hernberg, R., Stenberg, J., and Zethraeus, B. "Simultaneous In Situ Measurement of Temperature and Size of Burning Ghar Particles in a Fluidized Bed Furnace by Means of Fiberoptic Pyrometry." Combustion and Flame 95, nos. 1-2 (1993) 191-205. 

Sewage sludges from community facilities as well as from industrial plants are very often disposed of by incineration in fluidized bed furnaces [1]. The incineration is a combustion process at a relatively low temperature. The preheated air is blown through a... 

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