Cylindrical vacuum filter

Claim 1

In a continuous rotary drum vacuum filter comprising a rotary drum movable through a tank containing the liquid to be filtered, said drum having filtering compartments on its circumference, and an endless filter cloth belt trained over said drum and also over rollers spaced from said drum which guide said filter cloth belt through a zigzag path, the improvement which comprises: said filter cloth belt has enlarged resilient hems along both of its edges; a pair of endless roller chains each comprising rollers pivotally connected on opposite sides of the chain by connecting links, said chains being respectively disposed adjacent to and being connected to the edges of said filter cloth belt and extending with said filter cloth belt around a portion of said drum and also around said rollers, the connecting links of each chain facing the adjacent hem of the filter cloth belt having upwardly opening hooks and downwardly opening hooks positioned alternately along the entire length of the chain, the enlarged hems of said filter cloth belt being disposed between and partially encircled by said hooks of the respective chains so that the edges of the filter cloth belt are connected to the chains; said rotary drum having at each of its axial ends a radially outwardly projecting guide extending around the circumference of said drum, the connecting links on opposite sides of each chain being disposed on opposite sides of the adjacent cooperating guide so that movement of the chains around said portion of the circumference of the drum is closely guided by said guides on said drum; said rollers having means for engaging and guiding movement of said chains whereby the movement of said chains and said filter cloth belt is closely guided by said drum and said rollers; and first nozzle means disposed adjacent said rollers close to the beginning of said zigzag path for directing a blast of gas against the inner surface of said filter cloth belt for discharging cake therefrom.