Beach pitch

The scroll usually is carried on a hollow axial hub, through which the slurry feed tube passes to the feed zone. The diameter, the number, and the pitch of the conveyor flights are chosen to match the needs of the slurry being treated — as are the depth of the pond, the length of the bowl, the conveyor differential speed, and the angle of slope of the beach. 

The B" range of decanters manufactured by KHD (now Bird Humboldt) are unique in having one. or possibly two, nozzles in the bowl wall, allowing the discharge of the bulk of the thickened product. The remainder of the product is scrolled up the beach, which is much steeper than normal (as much as 45°). Discharge from the nozzle can be made intermittent by providing a zero pitch to the conveyor for less than one turn at the nozzle location, thus covering the nozzle for a fraction of each conveyor turn. 

The baffle di.sc comprises a plain disc welded to the conveyor hub somewhere between the feed zone and the cake discharge. On countercurrent decanters the usual location for the disc is at the foot of the beach. However, more recently, the disc has been seen situated in several positions on the beach from bottom to top. Ideally there should be a minimum distance, say one pitch, between the disc and the feed zone. This is to avoid turbulence from incoming feed at the periphery of the disc. 

A patent by KHD (now Bird Humboldt) specifies a standard pitch in the cylindrical section of the bowl with a narrower pitch on the beach [15]. This obviates the need for a baffle at the foot of the beach as the narrow pitch produces a deeper cake forming the seal. The narrow pitch provides a back pressure on which the standard pitch can work. 

When operating properly in DS mode, a decanter will be virtually full of cake, from end to end, and from bowl wall to pond surface. The conveyor will be pushing the cake towards the discharge ports against a restriction, a baffle or a narrowing of the conveyor pitch, or against the nip between conveyor hub and the beach. 

Scaling up between two decanter sizes is generally best done when there is geometrical similarity between them. This means the same beach angle, the same conveyor pitch angle, and the same conveyor and feed zone designs. When there are differences then the scale-up may not be reliable. 

More often referred to as the beach A complex form of cake baflle, comprising a flight section with larger pitch, stretching from the front of one main flight to the rear of another... 

We started out with several hours drive to the beach, our car loaded down with four of us and all the gear. Car = gasoline = fossil fuels = carbon dioxide. Whew That s a bad start. We pitched the tent (nylon), blew up the air mattresses (vinyl), and set out our coolers and camp furniture (aluminum and more plastics and synthetic fabrics). That s another load of materials sourced ultimately from fossil els, except for the aluminum, but it requires a huge amount of electricity for its production. We are pretty comfortably set up with a gas camp stove and gas lantern for cooking and lights—oops, more fossil fuels, more CO2. 

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