Classifying – separating – and assorting solids – Plural – diverse separating operations – Gaseous suspension and sifting
Reexamination Certificate
2000-04-24
2001-04-17
Walsh, Donald P (Department: 3653)
Classifying, separating, and assorting solids
Plural, diverse separating operations
Gaseous suspension and sifting
C209S021000, C209S152000
Reexamination Certificate
active
06216875
ABSTRACT:
FIELD OF THE INVENTION
This invention relates primarily to machines for size separation of particulate material for use within a dilute phase pneumatic conveying system in the food, feed and chemical processing industries, and for other applications.
BACKGROUND OF THE INVENTION
Generally, sifters utilized within a dilute phase pneumatic conveying system, include, for instance, a pressurized container with a screen or screens of desired mesh size therein. Commonly, the container is mounted in such a manner that it is vibrated to cause the materials provided at the input of the container to move across the screen and thereby to effect the sifting action.
As shown and described by Stone in U.S. Pat. No. 5,873,469, issued Feb. 23, 1999, there is an input system disclosed to enable the prevention of unwanted contaminants from passing through the screens, or breaking up upon entering and impingining upon internal components at high velocity. Stone accomplished this by providing a tangential inlet for air and material to be screened, coupled with an external carrying system for enabling air to bypass the screening surfaces. In this way, the full diameter of the system was used for the bypass screen, and the external air loop enabled this use.
Nevertheless, the machine occupied more space with the external loop, both visually and actually, and the saving of a circular area at the center of the bypass screen was only meaningful in terms of a small percentage of the overall screening area. Even more importantly, if incoming air were enabled to pass directly through the center of the screen, the disadvantages relate to the velocity of the material impacting because of the material going through that center area at high velocity with the assistance of the air. This latter point would therefore result in the contaminants breaking up and contaminating the results of the screening.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, a primary object of the present invention is to provide an air and material inlet orientation for a vibrating screener operating in a dilute phase pneumatic conveying system, which enables the prevention of unwanted contaminants passing through the screens, or breaking up upon contacting the screens due to impinging on internal components at conveying velocity.
A further and more particular object is to provide a tangential inlet for air and material to be screened, combined with the use of an internal, central channel by which air containing screened product from the first operating screen can be combined with air carrying screened product from the second operating screen, and discharging as a single stream of air and screened material.
These and other objects of the present invention are provided by a vibrating screener which features one or more vibration-imparting motors, a generally cylindrical container having a conical or other shaped bottom for outlet, a generally circular first operating screen for conveying air and undersized material flow and acting as a barrier for preventing undesired input materials from mixing with the air stream therethrough, and at least one generally circular second operating screen mounted within the container for separating oversized material from desired material output. The container provides a tangential input pipe for admitting input material and air to the container in a tangential direction with respect to the cylindrical axis of the container. The tangential orientation of the input pipe prevents inlet materials from impacting on a screen or upon any wall; but instead, the stream of air and solids admitted to the container generally form a cyclonic pattern, whereby for a vibrating screener, used for flour, for instance, unwanted bugs, trash and other contaminants are not degenerated and mixed with the food material, and the pressure drop on the operating screen is maintained at a sufficiently low level to prevent blocking of the screens, thereby to avoid damaging the screens.
The channel for carrying the air and screened material from above the first operating screen to below the second operating screen is central to the container, proximate its axis. This eliminates the need for an external bypass loop with its higher cost and space requirements. This is accomplished by closing the channel from above the first operating screen to below the second operating screen, where the air through the channel actually assists the screened product in its flow down the conical sides near the discharge of the machine, to the output thereof.
REFERENCES:
patent: 5323913 (1994-06-01), Papetti
patent: 5873469 (1999-02-01), Stone
Beauchaine Mark J.
Kason Corporation
Walsh Donald P
Yavner Stanley J.
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