Abstract:
A pressure filter for processing a large volume of liquid containing multiple internal vertical cartridges that are backwashed through a central backwash tube that travels axially and rotates during backwashing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No.  12 / 043 , 648  filed Mar. 6, 2008. 
     
    
     FIELD OF THE INVENTION 
       [0002]    A pressure filter for processing a large volume of liquid containing multiple internal vertical cartridges that are backwashed through a central backwash tube that travels axially and rotates during backwashing. 
       BACKGROUND OF THE INVENTION 
       [0003]    Pressure liquid filters containing cartridges or tubes with a permanent mesh covering filter media are commonly used but have limitations. Cartridge filters generally are removed manually and discarded after being used. Tube filters with wire mesh sock cover can be backwashed by compressed air shocking of the liquid and backflow occurs. This does not work effectively if longer tubes are used since the backwash liquid will escape to the lower end of the tube leaving the upper portion uncleaned. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention discloses a pressure vessel with cartridges that are 72 inches long with a monofilament polymeric filter mesh covering the 6″ diameter of the outside of the cartridge. To backwash this in a stationary tube would require 78 nozzles and 156 GPM per cartridge. With a filter with 50 cartridges would require 3900 nozzles and require 7800 GPM backwash. This would not be practical. With a tube that travels axially and rotates would require 8 nozzles and 16 GPM per cartridge or 400 nozzles and 800 GPM for 50 cartridges. 
         [0005]    The backwash tube is in the up position during filtration due to the affixed float and flow of liquid upward to the dome. A pressure switch triggers a backwash by closing the dirty supply and clean discharge valves, and simultaneously a clean system supply valve in the dome and a dirty outlet valve at the bottom open. At this point the dome liquid pressure acts on the backwash tube and downward forces overcome the buoyancy of the floats. Back-washing continues for 1 to 2 minutes requiring a pressure reducing assembly to reduce descending of the tube. An assembly inside the base of the tube contains a cylinder with limited storage of liquid (0.1 gallons) and metering it through a piston rod with multiple orifices to reduce the flow rate, which requires 14 stages of reduction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  illustrates tie entire filter assembly indicating all the filter components; 
           [0007]      FIG. 2  illustrates a wire diagram for the automatic electrical and hydraulic components. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0008]      FIG. 1  illustrates a pressure vessel body  1  with a head dome  4  with clean backwash supply valve  2   a  and dirty backwash discharge valve  2   b  closed during filtration and open during backwash. Valve  3   b  is a dirty liquid supply and  3   a  is clean discharge open during filtration and closed during backwashing. The dome  4  has a flange  5  and bolts  6  to contain a pressure plate  7  with machine flanges on the body  1 . A half coupling  8  is affixed to plate  7  and a short pipe  9  is screw attached forming a ball check valve  10  chamber  11  with liquid passage during filtration and closed during backwashing. 
         [0009]    A sleeve inside the chamber  12  is provided as a guide for a backwash tube  14  which has clamped on sponge floats  13  extending from lower backwash tubes  16 . Inside the base of the backwash tube  14  is a liquid reservoir chamber cylinder  15  with a 0.1 gallon volume having a stationary piston  17  with upper seals  24  and supported and affixed to an anchor block  23  with a liquid out and in passage hole  22 . 
         [0010]    In use, the central backwash tube  14  with affixed closed cell polymeric floats  13  contain diametrically placed nozzles with end deflectors for rotating the tube  14  during its (typically slow) descent to the bottom during backwashing, and inside of the backwash tube  14  is contained the affixed liquid storage reservoir cylinder  15  with stationary piston rod  17  with multiple orifices in series for reducing a downward travel to one to two minutes. The rod  19  contains a total of fourteen in line ⅛″ diameter orifices  18 , and so that the pressure is reduced equally along the fourteen station orifices. 
         [0011]    The backwash tube  14  travels vertically upward up to eighteen inches for filtration due to the tube buoyancy and travels downward during backwashing due to a pressurized dome liquid supply overcoming buoyancy forces exerted by the floats  13 . The backwash tube  14  is guided in a top cartridge sleeve and at the base from a flow reducing piston rod which is anchored to the base of the stationary cartridge cylinder  20 . 
         [0012]    Without this arrangement, use of a single orifice would have to be 0.009″ diameter, which would not be practical. The area gained is 0.125 2 /0.009=fourteen times larger and which has less chance of plugging. The cartridge cylinder  20  positioned in height extending fashion around the chamber  12  backwash tube  14  exhibits 5½″ O.D. and 72″ in length and is made of perforated plate. The cylinder  15  is affixed to a top of a 5″ O.D. pipe and the cylinder is covered with a monofilament polymer mesh  21  secured by clamps not shown. The pressure plate  7  contains a hole  25  sufficient in diameter for the liquid processed. 
         [0013]    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 R1 operating a four way valve  72 , opening filter inlet  3   b  and outlet  3   a  valves. The unit now is accepting, filtering and discharging filtrate. As pressure builds up due to accumulation of contaminants and the pressure rises to a point 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. 
         [0014]    The timer  75 , contact t1 closes the backwash valve  76  and backwash valves  2   a  and  2   b  open, which generates a liquid force to lower the tube  14 , and rotate it for approximately 60 seconds. At approximately 60 seconds timer T1  73  times out and opens its holding contacts t1 and closes the other contact t1 in series with filtration relay  71  resulting in the closure of the backwash valves  2   a  and  2   b  and reopening of filtration valves  3   b  and  3   a,  at which point normal filtration then resumes. The backwash tube  14  rises slowly by a reverse flow through the valve due to greater upward buoyancy and hydraulic forces. 
         [0015]    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.