Dust separation cyclones

Other Centrifugal Collectors. Cyclones and modified centrifugal collectors are often used to remove entrained Hquids from a gas stream. Cyclones for this purpose have been described (167—169). The rotary stream dust separator (170,171), a newer dry centrifugal collector with improved collection efficiency on particles down to 1—2 pm, is considered more expensive and hence has been found less attractive than cyclones unless improved collection in the 2—10-pm particle range is a necessity. A number of inertial centrifugal force devices as well as some others termed dynamic collectors have been described in the Hterature (170). 

Dust Separation It is usuaUy necessaiy to recover the solids carried by the gas leaving the disengaging space or freeboard of the fluidized becl GeneraUy, cyclones are used to remove the major portion of these sohds (see Gas-Sohds Separation ). However, in a few cases, usuaUy on small-scale units, filters are employed without the use of cyclones to reduce the loading of solids in the gas. For high-temperature usage, either porous ceramic or sintered metal has been employed. Multiple units must be provided so that one unit can be blown back with clean gas while one or more are filtering. 

Figure 4-46. General efficiency curves, applies specifically to helical entry cyclone dust separators. Courtesy of The Ducon Co.

Figure 4-47. General efficiency curve applies specifically to involute entry cyclone dust separators. Courtesy of American Blow/er Div., American Radiator and Standard Sanitary Corp.

Figure 7.2-11. Spray drier with heat recovery system 1. Spray tower and drying system 2. Air heater 3. Air fan 4. Cyclone dust separator 5. Wet dust separator and entrainment separator 6. Exhaust air fan 7. Pneumatic product conveyer 8. Intermediate product storage 9. Product sieving and packing 10. Wet product pumping system (by courtesy of BMA, TAG-Division). 

Particulate matter, separator, cyclone, electrostatic precipitator, wet dust scrubber, fabric filter, catalytic filtration, two-stage dust filter, absolute filter, high-efficiency air filter, and mist filter. 

This dust separated by pneumatic filters or cyclones can be recycled and used as internal seeds (disperse phase) for the production of new particles or for the layered growth (continuous phase) of existing particles. One effect of the production of internal seeds is the formation of a wide particle size distribution, while the deposition of the re-fed dust yields to growth of particles. 

Cristea E. D., Malfa, E., and Coghe, A. "3D Simulations and Measurements of Strongly Swirling Heavy Laden Flow Inside Cyclone Dust Separator." 3rd International Symposium on Engineering Turbulence Modeling and Measurements, May 27-28, 1996, Crete, Greece. 

Another cyclone may be provided at the exit gases in series to improve dust separation. 

Rock phosphate lumps are crushed and ground to a fine powder (about 90 % passing through 100 mesh) and stored separately. Cyclone and bag filters are used for arresting pollution due to fine dust. 98 % of sulphuric acid from main storage is pumped to the day tank. Treated water is used to dilute it to about 65-70 %. 

In a later development of this type of filter the dust-laden air or gas is pre-cleaned in a separate cyclone (Fig. 12). This air is then distributed to the individual compartments and passed through the granular bed. The finally cleaned air is extracted by a fan and discharged into the atmosphere. 

Consider the separation of dust particles from air by means of two cyclones connected in the following fashion. Feed air containing dust enters cyclone 1 the feed particle size distribution is Ff (Pp) = l-e"" p. The underflow from cyclone 1 is introduced with a small amount of air as feed to a small cyclone 2. The underflow from cyclone 2 is collected as dust from the system. The overflow air from cyclone 2 is mixed with the overflow air from cyclone 1 to obtain the cleaned air. The grade efficiency of the ith cyclone is given by... 

Shiljev, M. L Afonin, N. A. and Shiljaev, A. M. Research of process of a dust separation and water resistance in the cascade of direct-flow cyclone separators. Sulfurs. Building. H Dzgnzt. Tech. 1999, 8, 25-29, (in Russian). 

Brzik, D. A. Automation of Calculation of Parametres of the Cyclone Separator on the Basis of Mathematical Modelling of Process of a Dust Separation. Bryansk 2000. 

Belevitsky, A. M. Economy and Technical and Economic Optimisationof Dust-Collecting Plants (on an Example of Installations of Cyclonic Dust Separation) Help Supervising Material. Clearing of Gas Emissions L. 1982. 

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