Pneumatic transfer

Radial density gradients in FCC and other large-diameter pneumatic transfer risers reflect gas—soHd maldistributions and reduce product yields. Cold-flow units are used to measure the transverse catalyst profiles as functions of gas velocity, catalyst flux, and inlet design. Impacts of measured flow distributions have been evaluated using a simple four lump kinetic model and assuming dispersed catalyst clusters where all the reactions are assumed to occur coupled with a continuous gas phase. A 3 wt % conversion advantage is determined for injection feed around the riser circumference as compared with an axial injection design (28). 

FluidiZed-Bed Combustion. Fluidized-bed combustors are able to bum coal particles effectively in the range of 1.5 mm to 6 mm in size, which are floating in place in an expanded bed (40). Coal and limestone for SO2 capture can be fed to the combustion zone, and ash can be removed from it, by pneumatic transfer. Very Htfle precombustion processing is needed to prepare either the coal or the sorbent for entry into the furnace (41). 

An AC corona discharge in the throat leads to a cloud of charged droplets whose large momentum allows very long travel distances. Multiple devices for eliminating static discharges in powder silos have been tested [41] but the tests did not address typical flow rates for large capacity, dense phase pneumatic transfer operations. 

Consider first a dilute phase pneumatic transfer system operating at high velocity and relatively low mass flow density. As discussed in 6-3.1 this... 

The water-repellent wool is shredded by a flail and pneumatically transferred to a rotating drum nodulator to be further processed before bagging. 

With regard to the hazard concern from physical and mechanical handling, the expl nature of the materials can pose a special problem. For example, during pneumatic transfer of samples in fast neutron activation, the polyethylene vials containing the expl approach speeds of 15m/sec and come to rest against a metal stop at both irradiation and count stations. However at PicArsn (Ref 13), in over 1000 irradiations and pneumatic transfers with up to 2.3g of shock-resistant secondary expls such as TNT, HMX,... 

The sample aliquots were encapsulated in polyethylene vials for the irradiation period. Two aliquots of the sample plus two standards were irradiated in a pneumatic transfer irradiation system, one set (sample plus standards) for a long time period (12-24 hrs) and the other for a short time period (5 min). After irradiation the samples were immediately removed from the vials. The short-time sample was counted after decay intervals of 3 min, 30 min, and 24 hrs. The long-time sample was counted after a decay interval of 3 wks sometimes the decay intervals were 7-10 days. The typical neutron flux was 1013 neutrons/cm2/sec. Counting data were processed through computerized data reduction codes. Twenty to thirty elements were reported. 

Several major differences existed between this scheme and one compatible with the PBR facilities. The PBR did not have an operating pneumatic transfer irradiation facility, nor was there a sophisticated y-ray spectrum analysis and data reduction computer program available. Irradiation facilities at PBR were hydraulic. Aluminum capsules (rabbits) were used to contain and transfer samples to and from the core. 

Size and Power Requirement of a Pneumatic Transfer Line... 

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. 

Aminoplast is pneumatically transferred from bin (1) through a feeder and an injector to bin (2) provided with a cyclone separator and an agitator. 

Two series of irradiations were made with the UCI 250-kW TRIG A Mark I reactor. The first run consisted of irradiation for 30 s at a thermal neutron flux of 4.8 X 109 neutrons cm-2 s 1 using the facility s pneumatic transfer system. Samples were permitted to decay for 1 min and then counted for 2 min on a Ge-Li detector (21% efficiency) at a distance of 1.3 cm from the crystal and a gain setting of 0.8 keV per channel. Elements determined in this run were Al, Mg, Mn, Si, Sn, V, and Zr. 

Steam Requirement of a Turbine Operation 65 Performance of a Combustion Gas Turbine 67 Conditions of a Coal Slurry Pipeline 70 Size and Power Requirement of a Pneumatic Transfer Line 77... 

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