Restricted discharge

Fig. 6.M0 Diagram of an impact mill with hinged or fixed hammers on a horizontal rotor and discharge restriction (bar cage or screen) to avoid oversized particles in the product a) grate bars, b) cage with axially elongated holes, c) cage with round holes...

Discharge restrictions that may be in force to limit discharge of substances considered to be environmentally unacceptable (see earlier). 

Copper Sulfate has been used in large systems. It is limited to an algae-cide, and due to copper discharge restrictions has limited use. ... 

Poor performance can result from fan inlet eccentric or spinning dow, and discharge ductwork that does not permit development of hiU fan pressure. Sometimes inlet restrictions starve a fan and limit performance. To obtain rated performance, the air must enter the fan uniformly over the inlet area without rotation or unusual turbulence. This allows all portions of the fan wheel to do equal work. If more air is distributed to one side of the wheel, such as with an elbow on the inlet, the work performed by the lightiy loaded portions of the wheel is reduced and capacity is decreased by 5—10%. The use of an inlet box duct on a fan can reduce capacity by as much as 25% unless there are turning vanes in the duct. Use of the vanes reduces the capacity loss to around 5%. 

The basic form of the equation is normally modified so that the differential is expressed in pressure units and the flow coefficient is divided into the product of an experimentally deterrnined discharge coefficient, iC, and a series of calculated coefficients. In this form, for concentric restrictions ... 

In the case of the nozzle disk centrifuge, the flow of the soHds phase through the discharge nozzles may be so restricted that an excessive layer can accumulate inside the bowl sheU. When this layer reaches the zone utilized by the fresh feed stream entering the disk stack, reentrainment of the sedimented soHds by the fresh feed may lead to poor sedimentation performance. 

Screw Presses Figures 18-155 and 18-156 show screw presses. The rotating screw shown in Fig. 18-156 is of constant pitch and has a constant diameter of about 0.3 m (12 in). Pressure to squeeze juice from fruit placed in the press comes from restricting the opening at the end of the barrel with a hydraulically adjustable cone and by making the spindle of the screw thicker toward the discharge end. 

Water chemistry and operating changes were suggested but were deemed inadvisable because of legal restrictions concerning discharge of chemicals into local waters. 

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