Air-assist discharge of filter press cake

In a filter press including a frame having a pair of horizontally elongate and generally parallel side rails which extend lengthwise of the press and are sidewardly spaced apart, a first head structure stationarily mounted adjacent one end of said rails, a second head structure mounted on said rails for movement toward and away from said first head structure for respective closing and opening of said press, a plurality of filter plates movably disposed in generally side-by-side relationship to define a horizontally extending stack between said first and second head structures when said press is closed, each said filter plate mounting thereon a respective filter member which is independent of the filter members mounted on the other filter plates, said filter plates extending transversely between and being slidably supported on said side rails, each movable filter plate having parts which project outwardly from opposite vertical side edges thereof, and a shifter assembly for effecting shifting of individual said filter plates along the side rails toward the second head structure when said second head structure is in an open position, the improvement wherein said shifter assembly comprises:

• a shifter housing having a pair of opposite housing parts which are disposed on opposite sides of the press so that each said housing part is disposed adjacent a respective one of said side rails, said housing parts being supported for movement lengthwise along the press on an elongate guide structure which is fixed relative to and extends generally longitudinally parallel with and along a respective one of said side rails, said shifter housing also including a bridging part which extends transversely of said press and rigidly joins said housing parts together;
• drive means mounted on only one of said housing parts for linearly drivingly moving said housing lengthwise of said press generally along and parallel to said side rails, said drive means including a drive motor mounted on said one housing part and drivingly coupled to a driving member which is drivingly engaged with an elongate reaction member which is fixed relative to the respective side rail and extends lengthwise therealong;
• a plate sensing structure mounted on said housing for sensing an endmost said filter plate as associated with the closed stack of filter plates which projects horizontally away from said first head structure for stopping said drive means upon sensing said endmost plate;
• a plate shifter mechanism mounted on each said housing part and cooperating with the projecting part on a respective side of the endmost filter plate of the closed stack for effecting slidable shifting of the endmost plate along the side rails away from the closed stack toward the opened second head structure so as to position the shifted plate in an open position wherein it faces but is spaced a selected distance from the next endmost plate of the closed stack, whereby said first-mentioned and said next endmost plates are spaced apart so as to define a vertically extending clearance gap therebetween to permit downward discharge of filtrate from opposed faces thereof;
• plate bumping means mounting on said housing and cooperating solely with the endmost plate of the closed stack for imposing a bumping force onto the endmost plate of said closed stack in a direction generally transverse with respect to said side rails to effect loosening of filtrate adhered to the respective filter plate;
• a discharge assist mechanism mounted on said housing for simultaneously directing pressurized streams of air against opposed faces of said first-mentioned and said next endmost plates when said first-mentioned endmost plate is in said open position and said next endmost plate is still in contact with the closed stack to assist in discharging filtrate from the opposed faces thereof, said mechanism including an air discharge head assembly which is insertable into said gap and movable therein transversely of said press for simultaneously directing pressurized streams of air against the opposed faces of the two plates defining said gap, said mechanism including a driving device connected to said air discharge head assembly for effecting cyclic movement thereof into and out of said gap;
• and
• control means for (1) automatically stopping said shifter housing mechanism after said sensing structure senses the endmost plate of said stack and stops said drive means, (2) for thereafter activating said bumping means for effecting transverse bumping of solely the endmost filter plate of the closed stack, (3) for thereafter activating the driving device of said air discharge assist mechanism for causing the air discharge head assembly to move into the gap between the adjacent opened plates to discharge pressurized airstreams against the opposed faces thereof to assist in dislodging sticky filtrate therefrom, (4) for thereafter moving the air discharge head assembly out of the gap, (5) for then activating the shifter mechanism to shift the endmost plate of the stack into an open position, and (6) for thereafter automatically reactivating said drive means to forwardly advance the shifter housing toward the next endmost plate of said closed stack, and then repeating the aforementioned steps.