Cyclone capacity

Another important objective which must be considered is to provide adequate cyclone capacity for the application. The volume of feed slurry that a given cyclone can handle is related to the pressure drop across the cyclone. The relationship between flow rate and pressure drop for several different sizes of standard cyclones is shown in Figure 56. As shown, the flow rate increases as the pressure drop increases. In order to utilize this graph, the pressure drop used for calculating the separation is used to determine the flow rate for the cyclone diameter which was... 

The presence of higher concentrations of particles in the flow modifies the velocity profiles in the cyclone and increases capacity. Some authors take the view that the effect is the same as of higher liquid viscosity and density, and recommend the use of the apparent suspension viscosity of the feed slurry and density of the slurry rather than that of the suspending liquid. While this approach oversimplifies the real process in the cyclone, the increase in cyclone capacity with concentration is small anyway and the errors may be acceptable (in practice, clean liquid data are often used regardless of concentration and the capacity may then be adjusted in plant by throttling or by other means). 

Although performance curves are valuable in assessing classifier performance, frequently the cyclone overflow size analysis is used more than the d Q of the cyclone. In practice, clusters of cyclones (in parallel) are used to handle large capacities. Cyclones are manufactured in sizes ranging from 0.01 to 1.2 m in cyclone diameter, ie, the cylindrical section at the top (2,10). Capacities mn from 75 to 23,000 L/min. Materials of constmction vary widely. Rubber-lined or aH-polyurethane cyclones are used when abrasion is a problem. 

The WP L cyclone boiler will bum I DE continuously with coal, as about 5% of its fuel mix, with htfle or no modification. By contrast, pulverized-coal boilers, which account for about 80% of the coal-fired capacity in the United States, probably caimot bum tire chips without significant modifications. In these boilers, which bum very fine coal particles in suspension, the heavy chips will fall from the area where best combustion occurs. 

Because the cut size decreases with cyclone diameter (d g in fim = 5 in cm) and because the capacity, //s, also decreases with cyclone diameter... 

I/s = 0.022 ), high classification capacity at low cut sizes can only be achieved by feeding many cyclones of the same diameter. The manifolding of... 

Spray Drying and Agglomeration. Most instant coffee products are spray-dried. Stainless steel towers with a concurrent flow of hot ak and atomized extract droplets are utilized for this purpose. Atomization, through pressure nozzles, is controUed based on selection of the nozzles, properties of the extract, pressures used, bulk density, and capacity requkements. Low inlet ak temperatures (200—280°C) are preferred for best flavor quaHty. The spray towers must be provided with adequate dust coUection systems such as cyclones or bag filters. The dried particles are coUected from the conical bottom of the spray drier through a rotary valve and conveyed to bulk storage bins or packaging lines. Processors may screen the dry product to... 

The exhaust gases are generally discharged into dust and fume knockdown equipment to avoid contamination of the atmosphere. Gas-cleaning equipment includes cyclones, setthng chambers, scrubbing towers, and electrical precipitators. Heat-recoveiy devices are utilized both within and outside the lain. These result in an increase in lain capacity or a decrease in fuel consumption. Waste-heat boilers, grates, coil systems, and chains are used for this purpose. 

Cyclone A B C D E F G Approximate weight, lb H Evaporation capacity, lb water/hf Price,1 FOB shops... 

Based upon 1200 F air-inlet temperature. With an inlet temperature of 700 F the evaporative capacity would he half that given in the table. Prices are based upon carbon steel construction with cyclone collector (January, 1995). Motors and secondary dust collectors excluded... 

The sharpness of separation of the mineral from the gangue is dependent on (1) the stability of the suspension, which is influenced by the size of the medium (2) the specific gravity of the medium (3) the cleanliness of the medium (4) the cone angle (5) the size and ratios of the internal openings in the cyclone (inlet, apex, and vortex) and (6) the pressure at which the pulp is introduced into the cyclone. A 20° cone angle is the most common. Cyclone diameter will be determined by the separation to be made as well as by the capacity required. The 0.5- and 0.6-m (20- and 24-in) cyclones are most common in coal plants, whereas multiple cones of 0.25- or 0.3-m (10- or 12-in) diameter are used in higher-gravity separations. 

Figure 56. Water capacity for standard cyclones, after Afterbum.

This unit is good to pre-thicken feed to centrifugal filters and similar applications. One cyclone may satisfy a requirement, or the units can be arranged in parallel for large capacities or in series for removal of extreme fines. See Figure 4-53 for a counter-current wash system. Solids as small as 10 microns can be separated. 

The Bradley hydrocyclone has a lower capacity than the Reitema geometry but is more efficient. For the Rietema cyclone geometry the cor-relatins are (Antunes and Medronho, 1992)... 

Phenyl (Cohesive Technologies), the polymer-based Oasis HLB (Waters), the Cyclone (Cohesive Technologies), and the porous graphitized carbon-based Hypercarb (ThermoHypersil, Cheshire, UK) Cohesive s 2300 system was the HTLC component. Merck s monolithic reversed-phased Chromolith Speed ROD (RP-C18 (50 x 4.6 mm) served as the analytical column. The Oasis HLB, Cyclone TFC, and Hypercarb yielded the best retention capacity and good elution efficiency and volume. Recovery was 42 to 94% with a sample volume of 10 mL. Run time was 14 min. LODs were 0.4 to 13 ng/L for most compounds. 

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