Automatic foam remover for flotation tanks

Claim 1

In a flotation tank of substantially rectangular cross-section for treatment of waste water therein by causing the formation of gas bubbles which rise through the waste water body carrying insoluble and immiscible matter in the waste water with them to the surface of said body to form a layer of foam, froth or sludge on said surface which is maintained at a constant level by overflow means connected with the tank, an automatic foam remover comprising: a. a hollow beam extending horizontally across the top portion of said tank between two opposite side walls thereof and having its bottom edge at a distance above said waste water level with a downwardly open slot extending along said bottom edge, b. an elongate substantially flat-faced vane mounted within said hollow beam for pivotal movement on a horizontal axis above said slot and extending downwardly through said slot to a level below the surface of said waste water body, said slot being of significantly greater width than the thickness of said vane, c. conduit means providing communication between a vacuum source and the interior of said hollow beam, d. means at the ends of said beam supporting said beam for translatory movement on guide rails provided on said tank and extending along said two opposite side walls thereof, e. a horizontal shaft rotatably mounted on the outside of said tank and extending transversely of said guide rails, f. a sprocket wheel secured to each end of said shaft, g. an endless drive chain trained over each of said sprocket wheels and over an idler sprocket wheel at the opposite side of the tank, h. drive means operatively connected with said shaft for moving said endless drive chains in synchronism with each other continuously in one direction, i. a first horizontal lateral projection on each of said chains in alignment with each other, j. a second horizontal projection on each end of said beam and extending longitudinally of said beam outwardly above the top edge of said tank, k. link means connecting said first and second projections at each end of said beam, said link means being of variable effective length to permit variation of the distance between said first and second projections as said first projections pass around the sprocket wheels in the reversal of the direction of movement of said beam, whereby movement of said beam in one direction tends to cause compression of the foam in front thereof and thereby causes said vane means to pivot into engagement with the rear edge of said slot and thus subjects said foam in front of the vane means to the suction action of said vacuum source and thereby causes discharge of said foam through said conduit means, the operation being repeated during the reverse movement of said beam, this time with said vane means in engagement with the other edge of said slot.