Circular Filter Device

This invention is used to filter whey without the need of a storage/surge tank, thus eliminating a prime source of contamination. The invention is an improvement over prior art in that a two-shower system provides constant cleaning of the filter media and allows the use of fine mesh filters. This increases productivity and decreases the amount of fines lost during the filtration process.

The drawing shows the best mode of the invention.

The housing is made of an outer upstanding wall (1) connected to a bottom wall (2). Inside the housing are two inner upstanding walls (12) one of which supports a sloping screen (11). A fluid inlet (3) opens between the outer wall (1) and the inner walls (12). Three discharge outlets exit through the bottom wall: a centrally disposed passageway (4) removes the bulk of the large particles; one outlet (5) removes effluent (filtered whey) from the system; the other outlet (6) recycles effluent through a pump (7) to a rotatable shower means (8). The shower means comprises two sets of rotating shower arms: one shower arm (9) is located above a filter screen (11) and directs spray down onto the filter; the other shower arm (10) is located below the filter screen (11) and backwashes the underside of the filter screen.

Approximately ten pounds of cheese is made from each one hundred pounds of milk. During the draining of the resulting ninety pounds of whey, small bits of cheese curd (fines) escape. Since there is a trend to use larger vats, to use pumps excessively, and to use harsh stirring methods, the small and acceptable loss of fines in earlier machines has become a much greater loss. Furthermore, the disposal of whey with a heavy solids content presents large ecological problems. Subsequent whey refinement processes--evaporation, reverse osmosis treatments, and cream separation--are very difficult due to the presence of these fines particles. In addition, the use of larger vats exacerbates the problems of maintaining pH, texture, and temperature, and preventing contamination. The present invention teaches a closed system (which prevents bacteriaphage and other contamination) utilizing a filter screen which may be cleaned in place by means of an upper and lower shower. Unfiltered whey direct from the vat is introduced into the outer compartment of the circular vessel so that overflow occurs perfectly around the perimeter of the filter screen which covers the inside compartment. An opening in the center of the screen, which is slightly sloped, accepts the fines that are recovered from the whey. These may be instantly returned to the original vat by means of a small pump. A portion of the filtered whey is taken from the inner compartment and pumped through a drive shaft mounted in the center of the cover. Inside the cover a top shower consisting of three elbow-shaped arms with built-in slotted nozzles sweeps the curd to the central passageway located in the middle of the filter screen. Since warm cheese tends to become fixed into the screen material, a second shower resembling the first but located below the filter screen sprays upwardly against the bottom of the filter. This bottom shower is connected to the top shower, deriving its rotation and its liquid from the top shower. This is the preferred mode; as an alternative, these showers may be driven by independent rotation and liquid means. Cheese fines are thereby prevented from collecting in or on the screen material.

The state of the art to date fails to incorporate this second shower and, therefore, is ineffective for the filtering of whey. Ellila (U.S. Pat. No. 3,112,263) teaches a screen sloping to a center outlet and equipped with a single shower. This device, however, has no second shower, nor does it contain outlet means to recycle filtered material. In practice this means that Ellila's invention is ineffective for the filtering of high bulk slurries of which cheese whey is only an example. Another patent, Stinson (U.S. Pat. No. 2,582,401) teaches a three-tiered device for filtering and cleaning industrial effluent water. Again, this invention incorporates only one shower and only filters fluids with a very low bulk content and small particle size.