Abstract:
A liquid filter with multiple vertical filter tubes covered with a permanent filter septum that can be backwashed through an inner backwash tube with radial nozzles that rotate the tube and advances it up by a float in the top clean compartment and descends with liquid pressure.

Description:
FIELD OF THE INVENTION 
       [0001]    An improved backwash apparatus, such as incorporated into a liquid filtration pressure vessel incorporating a plurality of stationary and permanent cylindrical shaped filter cartridges. 
       BACKGROUND OF THE INVENTION 
       [0002]    Pressure liquid filters containing a wire mesh or synthetic bag elements are extensively used as a final polishing filter. Settling tanks and pre-filtration often do not remove all existing contaminants which have accumulated during normal fluid flow. Therefore, and during critical machining operations, an absolute removal of all such contaminants is imperative. 
         [0003]    Bag filters and other types of cartridge filters are also often employed. Cleaning of these filters require manual labor, including disassembly and replacement of the cartridge elements. Such tasks are time consuming and expensive, both in terms of part and labor costs. 
         [0004]    Other permanent element tube filters backwash with the shock introduction of compressed air. This does not work effectively if longer tubes are used, since the liquid does not backwash effectively and most of the backwash simply escapes at the lower end of the element. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention discloses an improved backwash apparatus, such as incorporated into a liquid filtration pressure vessel, and which overcomes the difficulty of cleaning longer length (e.g. such as 6 foot long) filter tubes and by backwashing all of the filtration surfaces. The present invention incorporates a backwash tube that both rotates and translates up and down covering the entire filter area of the cartridge. The present invention further covers all the tube area because it is rotates at the same time is linearly translates up and down inside of the stationary and elongated filter cartridges(s). 
         [0006]    In this fashion, a 90% reduction in the nozzle and backwash flow can be achieved in comparison to that needed in the event of employing stationary fluid jets. Specifically, and again in the example of filtration vessel with 6′ backwash tube, an embodiment of the present invention is capable of incorporating eight combination rotating and linearly traversing nozzles, thus using a total volume of 16 gallons per minute (GPM) of water. In comparison, a total of 78 stationary nozzles expending 156 GPM would be required in providing the same backwash effect. As such, the present invention results in better use of long tube area filters, with lesser wasted processed water and more efficient cleaning processes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Reference will now be made to the attached drawings, when read in combination with the following detailed description, wherein like reference numerals refer to like parts throughout the several views, and in which: 
           [0008]      FIG. 1  is a cross section of the completed filter with backwash tube and filtration unit including floats; and 
           [0009]      FIG. 2  is a control diagram illustrating valve operations necessary for performing the backwashing of the filtration unit. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0010]      FIG. 1  is a cross section view of the filter vessel and the internal cartridge. 
         [0011]    The filter vessel consists of a top head dome section  14 , and a bottom tube body section  12 , with a platen  16 , between them and bolted  20 , through flanges  22 . Vessel has filter valves  42  and  44  and backwash valves  46  and  48 , and a base  65 . 
         [0012]    The inside of the vessel contains filter cartridges  30 , affixed to the platen  16 , and disposed vertically. The filtration area consisting of a perforate tube  23 , covered with a filter bag  26 , made of a polymeric fabric, covering the outside of the perforate tube  23 . 
         [0013]    The cartridge  30 , contains a central backwash tube  36 , which is affixed to a float  40 , in the top dome  14 , and enters the cartridge  30 , and is contained in a guide tube  25 , and extending downwardly with a series of spray nozzles  38 , mostly directed to the filter septum  26 , and partially deflected to create a tangential torque for tube rotation. 
         [0014]    The cartridge  30 , near the top also contains a check valve chamber  28 , consisting of a circumferential plate with a series of holes  31 , allowing filtrate to move outwardly with polymeric balls  34 , and closing the holes during backwash. 
         [0015]    The backwash tube  36 , contains a hydraulic method for lowering the backwash velocity of the backwash tube by restricting liquid flow from a reservoir chamber  60 , near the bottom of the backwash tube. 
         [0016]    A reservoir chamber  60 , consists of a closed tube  60 , inside the lower portion of the backwash tube  36 , containing a top compartment  61 , with a ball opening the top port when tube is rising and filling the chamber  60 , and closing the port  61 , on the down stroke. 
         [0017]    The reservoir chamber  60 , acts like a moving cylinder with a stationary inside piston rod (rod)  64 . In the downward wash cycle as the cylinder travels the rod displaces liquid volume from the chamber  60 , and is now directed between a close fitting rod and the cylinder. The close fit between the rod and the cylinder starts to cut down the rate fluid is evacuated from the chamber. 
         [0018]    Since the volume in the reservoir chamber is small, the hydraulic pressure would lower the tube in less than 5 seconds. To get a practical backwash requires 45 to 60 seconds, a flow control device is used to restrict the discharge of the reservoir chamber. 
         [0019]    A flow control valve  63 , installed after exiting from the reservoir chamber  60 , consists of a series of groves and lands in a tube with a close fitting rod  64 . A multiple entry and exit from an orifice reduces flow rate at each stage by 48%. With six stages at 45:1 flow reduction is achieved, which slows the tube decent to approximately 45 to 60 seconds. The rod  64 , extending beyond the flow control valve  63 , is pressed into a swivel bearing  66 , affixed to plate  65 , and acts to hold the orifice rod  64 , anchors and also adjusts the position of the base of the backwash tube. 
         [0020]    FIG. II is an electrical control diagram for operational sequencing of the filter. First it is manually started with switch  70 , which energizes relay  71 , connected to a solenoid contact R 1  operating a four way valve  72 , opening filler inlet and outlet valves  42  and  44 . The unit now is accepting, filtering and discharging filtrate. As pressure builds up due to accumulation of contaminants and the pressure rises where it trips a pressure switch  74 , which is wired in series to a timer  73 , with instantaneous contact that drops out the filtration control relay  71  for the duration of the wash cycle, and has parallel contact around the pressure switch keeping the wash cycle operating for approximately 60 seconds. At the same time  73  and  75 , get energized and  75  has a 10 second delay contact t 2  when no liquid is passing through the filter and allows the float to raise the backwash tube  36 , approximately in 10 seconds. After the dwell time timer  75 , contact t 2  closes the backwash valve  76  and backwash valves  46  and  48  open, which generates a liquid force to lower the tube  36 , and rotate it for approximately 50 seconds. At approximately 60 seconds timer T 1   73  times out and opens its holding contacts t 1  and closes contact t 1  in series with filtration relay  71  resulting in the closure of the backwash valves  46  and  48  and opening filtration valves  42  and  44 . Normal nitration then resumes. 
         [0021]    Having described my invention, other and additional preferred embodiments will become apparent to those skilled in the art to which it pertains and without deviating from the scope of the appended claims: