Presses – Automatic or material triggered control – Of material addition – deposition – or discharging
Patent
1996-01-24
1998-02-03
Gerrity, Stephen F.
Presses
Automatic or material triggered control
Of material addition, deposition, or discharging
100117, 100127, 100148, B30B 918
Patent
active
057132682
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a press with a screw for continuously dewatering a suspension. The screw is powered and forwards the suspension. A housing accommodates the threaded section of the screw and a downstream compression section with a variable squeeze. There is in an intake for the dilute suspension at one end of the press and an outlet for the dewatered suspension downstream of the compression section at the other end.
Various types of screw-driven press are known. They can be employed for dewatering various types of suspension (e.g. rejects, slurries, sludges, and pulps). The dilute suspension is poured over the rotating screw through a funnel-shaped intake, and the screw forwards it to the press's outlet. The press accommodates what is called a compression section that also accommodates the squeeze. The screw must accordingly generate enough force in the suspension to overcome the resistance exerted by the squeeze.
The squeeze is embodied in some screw-driven presses by active components, components, that is that can be controlled or regulated. These components constitute mechanically, pneumatically, or hydraulically operated disks, cones, or sheets. The pressure at which they release the suspension is determined by other parameters (type of suspension, final dryness, etc.).
Passive squeeze is also known. It occurs in presses with a housing in the form of a wire basket (Selhe housing) that accommodates a screw followed by a series of compression sections with an unscrew instead of a screw and upstream of the outlet. The compression sections have specific functions. pressure (with the screw acting like a brake). will be drier as it emerges from the press.
The length of the compression section has an essential influence on the press's operating parameters (power consumption, final dries content, etc.) It can as is known be calculated when the length of the basket is constant from the number of flights on the screw and is established empirically or during start-up. The length of the compression section will accordingly remain invariable in operation. There are considerable drawbacks. type of suspension (its friction, shear resistance, etc.) and cannot be varied. As the behavior of the suspension changes, it can lead to operating problems. If pressure losses are too high, power consumption and thrust might increase unacceptably. If friction is too low, the compression section might not be long enough to generate enough pressure. The final dries content might not be high enough. Experience demonstrates that too short a compression section can be compensated for only by an active squeeze mechanism. The suspension could cake up, and the stresses (e.g. torque and thrust) might be too high when operations are resumed. the press. If any gets into the press, even briefly, unflocculated sludge will not be able to force plugs of sludge out of the compression section, and the press will "jam". directly on the basket in the compression section depending on the dewatering properties and shear resistance of the suspension, and the moister suspension can slide over them. The press's effectiveness can be essentially deteriorated. These deposits can be removed only at considerable expenditure.
SUMMARY OF THE INVENTION
The object of the present invention is accordingly an improved screw-driven press of the aforesaid genus that, without the aforesaid drawbacks, will dewater a suspension efficiently, have a squeeze that can be varied as necessary, and be easy to empty and clean.
The axially displaceable wire basket in-the vicinity of the compression section in accordance with the present invention is a simple means of rapidly adjusting to the prevailing operating conditions the squeeze exerted by the highly efficient compression section and specifically without having to modify the press substantially. These conditions depend on the nature of the suspension and specifically on its frictional behavior and shear resistance. The adjustment can be very rapid. Dewatering will always be ideal and dryness satisfactory,
REFERENCES:
patent: 2678600 (1954-05-01), Allen, Jr.
patent: 3276353 (1966-10-01), Burner et al.
patent: 3394649 (1968-07-01), Kemper et al.
patent: 4291619 (1981-09-01), Hunt et al.
Janus Karl-Heinz
Krieger Uwe
Andreas Kufferath GmbH & Co. KG
Fogiel Max
Gerrity Stephen F.
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