Efficiency multicyclone

SNR s fluidized-bed cogeneiation system is an early example of the commercial development of AFBC technology. Foster Wheeler designed, fabricated, and erected the coal-fired AFBC/boHer, which generates 6.6 MWe and 37 MW thermal (also denoted as MWt) of heat energy. The thermal energy is transferred via medium-pressure hot water to satisfy the heat demand of the tank farm. The unit bums 6.4 t/h of coal and uses a calcium to sulfur mole ratio of 3 to set the limestone feed rate. The spent bed material may be reiajected iato the bed as needed to maintain or build bed iaventory. The fly ash, collected ia two multicyclone mechanical collectors, may also be transferred pneumatically back to the combustor to iacrease the carbon bumup efficiency from 93%, without fly ash reiajection, to 98%. 

To obtain a high efficiency, the vessel diameter must be small, but in order to accommodate a required volumetric rate, many units in parallel may be needed. These units, called multicyclones, may be incorporated in a single shell at a cost that may be justifiable in view of greater efficiency and lower pressure drop. 

Cyclones (Figure 4-3). These are robust and not susceptible to fouling or wax. Multicyclones are compact and are reasonably efficient for foam, but not for slugs. The efficiency of a cyclone decreases with increasing diameter, and cyclones are not applicable above 5 ft. diameter. They possess a good efficiency for smaller flow rates. However, cyclones are expensive to operate, especially under vacuum conditions, because they have a higher pressure drop than either a knockout drum or a demister separator. 

The Efficiency Coefficient of a Separator with Multicyclone Orifices... 

We can give an idea of the scale where this becomes a consideration. In a cyclone with a tangential inlet of circular cross section working with ambient air at an inlet velocity of 15 m/s, = 2 x 10 would correspond to an inlet diameter of 2 cm. The reduced efficiency is therefore only a feature in small sampling cyclones or in very small multicyclone banks. Cyclones in small industrial units comprising multicyclone installations are seldom less than 15 cm in diameter. 

Definition Vertical multicyclone separator for removal of solids and liquids with liquid removal efficiency of 100 percent for particles of 10 microns and larger. 

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