Two-stage cyclones

The cyclones are typically designed with diameters of 100—160 cm for ease of maintenance. Cyclone inlet velocities are usually restricted to 18—21 m /s in the first stage and to 20—26 m/s in the second stage to achieve satisfactory pressure drop and erosion characteristics (62). The number of sets of two-stage cyclones thus depends on the total gas flow. Finding room to house all the necessary cyclones within the regenerator frequently requires considerable ingenuity (62). 

Figure 4-48. A two-stage cyclone system. (Source Bill Dougherty, BP Oil Refinery Marcus Hook, PA.)...

Figure 5.6. Components of pneumatic conveying systems, (a) Rotary positive displacement blower for pressure or vacuum, (b) A rotary airlock feeder for fine materials (Detroit Stoker Co.), (c) A four-compartment receiver-filter (Fuller Co., Bethlehem, PA), (d) A two-stage cyclone receiver, (e) The Fuller-Kinyon pump for cement and other fine powders. Powder is fed into the aeration chamber with a screw and is fluidized with compressed air (Fuller Co., Bethlehem, PA).

A pneumatic transfer line has 300 ft of straight pipe, two long radius elbows, and a lift of 50 ft. A two-stage cyclone is at the receiving end. Solid with a density of 125 lb/cuft is at the rate of 10 tons/hr and the free air is at 5000ft/min. Inlet condition is 27psia and 100°F. Investigate the relation btween line diameter and power requirement. 

A sketch of a typical two-stage cyclone is shown in Figure 7-8. Some of the more common causes of cyclone operational failures are ... 

The top of the fluidized bed has a more or less clearcut surface, but some solids are entrained and a certain freeboard is necessary to minimize this. To avoid catalyst loss and elutriation, the exit stream flows through a two-stage cyclone. The catalyst is fed back to the bed through pipes called diplegs , which have a seal at their bottom for preventing leakage of bed fluid. 

Coal with a top size of 2.4 mm (0.09 in) can be dewatered using two-stage cyclones as well as solid-bowl centrifuges, but the overall moisture is only reduced to 19%. 

The process of separation of slimes from coarse materials at the tailings dam must be designed carefully. It can be as simple as a spigot when there is a considerable portion of coarse materials, or as complex as a two-stage cyclone when there are a lot of fines in the tailings. 

It is clear that the fines (<74 xm) constitute 67% of the particles. These tailings wUl require two-stage cycloning to separate coarse from fine particles. 

High VaUey Copper, British Columbia, Canada (two stage cyclone). 60% passing, 200 Tyler mesh (74 p-m). 

BHP Rio Tintaya, Peru (presently under constmction). Will use a two-stage cyclone station. 

Fig. 1.3.5. A collection of two-stage cyclones suspended from the vessel head of a modern FCCU regenerator prior to installation. Photo courtesy of TapcoEnpro International...

Figure 11.4.1 is a simple illustration of an internal, two-stage cyclone system contained within a fluidized bed vessel (typically a reactor or regenerator). We wish to compute the backup h of the solids within the second-stage dipleg above the fluid bed level, which is at the vessel s lower cylindrical/conical transition. 

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