BACKWASHING FLUID FILTERING SYSTEM
BACKGROUND
[0001] The present disclosure relates to fluid filtering systems of the type connected
inline for filtering pressurized fluid flowing in a processing system. Typically, filters
employed for inline filtering of fluids employ a pressure vessel with a removable lid
having an inlet adapted for connection to a source of pressurized fluid and an outlet
adapted for connection to a fluid discharge line for continuing flow of the fluid in the fluid
processing system. Filtering systems of this type also are known to employ a
removable assembly of filter media elements readily removable from the pressure
vessel upon opening of the lid. However, in service it is desired to minimize the need
for shutting down the fluid flow system and depressurizing in order to open the pressure
vessel lid and replace the fluid filter cartridge.
[0002] Filter cartridges may employ an array of tubular filtering members disposed
between headers or tube sheets for positioning in the pressure vessel such that the inlet
communicates with the interior of the filter tubes and the outlet is isolated from the inlet
and communicates with fluid flowing exteriorly of the tubes. In service, it has been
experienced that filtered foreign material, particularly particulate material, accumulates
rapidly on the interior surface of the filter media tubes and results in clogging portions of
the filter thereby decreasing the rate of flow through the filter which affects the fluid
system operation. Thus, it has been desired to find a way or means of removing the
trapped filtered material from the surface of the filter media in service without requiring
shutdown of the system and replacement of the filter cartridge. It has been further
desired to have the capability to automatically remove such material in a manner so as
to maintain the desired rate of flow through the filtering system.
SUMMARY
[0003] The present disclosure describes a fluid filtering system with a pressure
vessel of the type having a removable lid and a filter cartridge or filter media elements
disposed therein having a plurality of tubular filtering elements disposed in an array
between tube sheets defining an inlet and outlet chamber in the pressure vessel. The
inlet chamber communicates flow from a pressure vessel inlet exclusively through the
interior of the tubes and fluid discharging from the filter media tubes flows into the outlet
chamber which communicates with an outlet of the pressure vessel. The filter media
elements have a centrally disposed core tube isolated from the outlet chamber which
encloses a shaft extending through and journalled for rotation in the tube sheets and
having a paddle valve member connected thereto closely adjacent the inlet ends of the
tubular filter elements and an outlet disc valve member disposed for rotation with the
shaft closely adjacent the outlet end of the filter media tubes. The outlet ends of the
filter media tubes communicate with a drain chamber formed inside the pressure vessel
by one of the cartridge tube sheets with the drain chamber isolated from the outlet
chamber and connected to an atmospheric drain provided in the pressure vessel.
[0004] In one version, the end of the shaft with the discharge disc extends outwardly
through the pressure vessel drain chamber through a rotary seal and is connected to a
motorized rotary drive mechanism or speed reducer for effecting selective rotation upon
energization of the motor. In another version, the motor and speed reducer are
mounted on the lid. A paddle valve rotating with the shaft is operative to progressively
block the inlet flow to individual tubular filter elements while the discharge disc valve
member permits the drain to be open to the drain circuit which may be at atmospheric
pressure. This causes the pressure in the interior of the particular tube to drop to a
level below that of the outlet chamber thereby causing backflow through the selected
filter tube to remove trapped particulate matter from interior of the filter media tube and
flush the matter to the drain. Continued rotation of the shaft causes progressively
similar blocking and draining of the remaining filter media tubes in the array. The
filtering system of the present disclosure thus permits selective remote control of
removal of trapped filtered material from the filter media tubes in the filter cartridge
without the necessity of depressurizing the system and removing the cartridge. The
back flushing of the system of the present disclosure may be performed at sufficient
intervals to maintain the desired flow rate in the filtering system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIGURE 1 is a side elevation view of the filtering system of the present
disclosure with portions of the pressure vessel wall broken away to expose the interior
components of one version of the system;
[0006] FIGURE 2 is a view similar to FIG. 1 of another version of the filtering system
of the present disclosure;
[0007] FIGURE 3a is a view of the paddle valve and discharge disc valve in position
with respect to one of the filter tube elements permitting normal flow therethrough;
[0008] FIGURE 3b is a view similar to FIG. 3a of the paddle valve rotated to block
the inlet of the filter media tube;
[0009] FIGURE 3c is a view similar to FIG. 3a showing the paddle valve maintaining
the inlet end of the tubular filter media blocked with the disc valve opening the discharge
end to the drain chamber;
[0010] FIGURE 3d is a view similar to FIG. 3a showing the paddle valve admitting
inlet pressure to the filter media tube with the discharge end open by the disc valve to
the drain chamber;
[0011] FIGURE 4 is a plan view of the paddle valve employed in one version of the
filtering system of the present disclosure; and,
[0012] FIGURE 5 is a plan view of the discharge disc valve employed with the
paddle valve of FIG. 4 .
DETAILED DESCRIPTION
[0013] Referring to FIG. 1, one version of the filtering system of the present
disclosure is indicated generally at 10 and includes a pressure vessel having a wall 12
with a removable lid 14 secured thereto by any suitable expedient, as for example,
clamps or bolts (not shown) disposed peripherally about an annular flange 16 provided
on the lid and an annular flange 18 provide on the pressure vessel. The pressure
vessel has, adjacent the flange 18, an inlet fitting 20 having an inlet passage 22
communicating with the interior of the pressure vessel and an annular flange 24
provided thereon which is adapted for connection to a line (not shown) supplying a flow
of fluid pressurized at an inlet pressure P,. The pressure vessel has an outlet fitting 26
provided thereon located adjacent the end of the vessel remote from the inlet 20 and
fitting 26 has an outlet passage 28 formed therein communicating with the interior of the
vessel wall and an annular flange 30 provided thereon which is adapted for connection
to a discharge line (not shown). The lower end or bottom of the pressure vessel wall
has provided thereon a drain fitting 32 with a drain passage 34 communicating with the
interior of the pressure vessel; and, the drain passage 34 is adapted to be open to
atmospheric pressure denoted Patm selectively upon actuation of a remotely disposed
drain valve (not shown).
[0014] A filter cartridge assembly indicated generally at 36 is disposed in the
pressure vessel upon removal of the lid, and has a pair of annular spaced headers
comprising an upper tube sheet 38 and a lower tube sheet 40, the tube sheets having
disposed therein respectively opposite ends of a plurality of hollow permeable tubular
filter media elements 42 disposed in circumferentialiy and radially spaced array or
arrangement. The tubular filter elements 42 are disposed about a tubular core 44 which
has one end thereof connected to the upper tube sheets 38 and the opposite end
connected to the lower tube sheets 40 in such as manner as to close the annular space
about the tube between the tube sheets.
[0015] The upper tube sheets 38 has its periphery sealed about the inner periphery
of the wall 12 of the pressure vessel so as to define an inlet chamber 46 communicating
with inlet passage 22 and the interior of each of the tubular filter elements 42 which
have one end of each tube open through the tube sheet 38 to the inlet chamber 46.
The lower tube sheet 40 has the periphery thereof contacting the inner periphery of the
vessel wall 2 so as to form a closed outlet chamber 48 between the tube sheets 38,
40; and, chamber 48 isolates the exterior of the filter tubes 42 from the inlet chamber
46. The tube sheet 40 also defines the drain chamber 50 which is isolated from the
outlet chamber 48 but communicates with the drain passage 34. The outlet passage 48
communicates the exterior of the filter media tubes 42 with the outlet passage 28. In
normal service operation, fluid at the pressure P, enters inlet chamber 46 and flows into
the interior of the filter media tubes 42 and also to the drain chamber 50 which it will be
understood in normal service is closed by the unshown remote drain valve. The inlet
pressure P, causes fluid to permeate the filter media tube 42, flow therethrough and
enter the discharge chamber 48 and flow outwardly therefrom through outlet passage
28 at a discharge pressure P0. Under normal operation 100% of inlet flow will pass
through media outlet passage 28.
[0016] A shaft 52 is received through core tube 44 and an upper end thereof is
journalled for rotation in a bushing or bearing 54 provided at the upper end of core tube
44; and, the opposite lower end of the shaft is journalled in a similar bushing 56
provided in the tube sheet 40. The shaft 52 extends outwardly of the pressure vessel
wall through drain chamber 50 and through a port collar 58 formed in the lower end of
the pressure vessel. The end of the shaft extending through port 58 is sealed for
rotation therein by suitable seal 60 and is connected by a rotary coupling 62 to a speed
reducer 64 driven by motor 66 which is remotely energized selectively by suitable
controls (not shown).
[0017] A paddle valve member 68 is disposed closely adjacent the upper ends of
tubes 42 and is connected to rotate with the upper end of shaft 52 extending through
tube sheet 38. The paddle valve member 68 is connected to the upper end of the shaft
52 by hub 69. A disc valve member 70 having a plurality of arcuate slots 72 formed
therein is disposed closely adjacent the tube sheet 40 and lower ends of tubes 42 and is
operative to rotate with shaft 52 by a hub 74 connected to the shaft 52.
[0018] Referring to FIG. 2, another version of the filtering system of the present
disclosure, indicated generally at 100, includes pressure vessel 102 with a lid 104
removable secured to a flange 106 provided on the pressure vessel. The pressure
vessel has an inlet fitting 108 receiving pressurized fluid at an inlet pressure P, and an
outlet fitting 110 discharging pressure fluid at pressure P0 and a drain fitting for
discharging filtrate contaminated flow to atmospheric pressure in a manner similar to the
version of FIG. 1.
[0019] The system 100 has a filter cartridge assembly 114, similar to the cartridge
assembly 36 of the version of FIG. 1, disposed in the pressure vessel 102. The
cartridge has an upper tube sheet 116 and a lower tube sheet 118 respectively forming
an inlet chamber 120, an outlet chamber 121 in a manner similar to the version of FIG.
1. Inlet chamber 120 communicates fluid pressure P, from fitting 108, to the interior of a
plurality of filtering tubes 122 disposed in an array between tube sheets 116, 118 with
the cartridge 114 including a core tube 124 forming the inner wall of the outlet chamber
121 .
[0020] The lower tube sheet 118 of the cartridge 114 forms a drain chamber 126 in
the lower end of the pressure vessel which drain chamber is isolated from the outlet
chamber and communicates the interior of the filter tubes with the drain 112 when
selectively opened by a remotely controlled valve (not shown) to exhaust the drain
chamber 126 to the atmosphere. The drain chamber 126, in normal operation with
drain 112 closed, is open to the interior of the filter tubes 122 and is thus, in service,
maintained at the inlet pressure P,.
[0021] A shaft 128 is received through core tube 124 and journalled in tube sheet
116 by a suitable bearing 130 provided with a rotary seal 132. The end of the shaft
extending through the bushing 130 has a paddle valve 134 connected thereto and
spaced closely adjacent the upper end of the tubes 122 and tube sheet 116. The shaft
has its upper end thereof extending through lid 104 in a rotary sealing manner and is
operatively connected to a drive unit 136 which may include a motor and speed reducer.
The drive unit 136 may be releasably connected to the shaft 128 to permit ready
removal of the lid 104.
[0022] The lower end of the shaft 128 is journalled for rotation in a suitable bushing
or bearing 138 disposed on the inner surface of the wall of the pressure vessel forming
drain chamber 126.
[0023] A rotary discharge disc valve member 140 is disposed closely adjacent the
lower ends of the filter tubes 122 and tube sheet 118 in drain chamber 126 and has a
hub 141 connecting the disc valve 140 to shaft 128 for rotation therewith.
[0024] Referring to FIG. 3a, the paddle valve 134 is shown, with tube sheet 116, 118
omitted for clarity, positioned with respect to one of the filter tubes 122 so as to permit
fluid at inlet pressure P, to enter the interior of the tube 122 through its upper end; and,
the disc valve 140 is positioned to block discharge from the interior of the tube to the
drain chamber 126. In the present practice, paddle valve 134 and disc valve 140 are
secured to shaft 152. Flow entering tube 122 is free to permeate the media and pass
into outlet chamber 121 . Solid material captured will accumulate on the interior surface
of tubes 122. In this position the element tube is isolated and no flow occurs through
the tube or through the media.
[0025] Referring to FIG. 3b, the paddle valve 134 has been rotated counterclockwise
by an amount to cause paddle valve 134 to block the inlet of tube 122; whereas disc
valve member 140 remains positioned to continue to block flow outwardly from the
interior of the filter tube 122.
[0026] Referring to FIG. 3c, the shaft 152 has been rotated further counterclockwise
from the position of FIG. 3b to a new position where the paddle valve member 134
remains blocking the inlet of the filter tube 122 and the disc valve member 140 is moved
to a position wherein an arcuator sector slot 142, formed in the disc valve member 140,
opens the interior of the filter tube 122 at its lower end to the drain chamber 126 and to
atmospheric pressure through fitting 112 it being understood that the unshown drain
valve is now open. The lowered pressure on the interior of the filter tube 122 thus
causes a negative pressure differential across the filter tube 122 by virtue of the
pressure in the interior of the tube 122 being at a substantially lower pressure than the
pressure P0 in the outlet chamber 114 surrounding the filter tube 122. This results in
back flushing of particulate material on the interior of the tube 122 downwardly in the
tube 122 into the drain chamber 126 and outward through drain fitting 112.
[0027] Referring to FIG. 3d, shaft 152 has been further rotated in a counterclockwise
direction from the position of FIG. 3c to a position in which paddle valve 134 opens the
upper or inlet end of filter tube 122 to inlet pressure with the slot 142 in disc valve 140
maintaining the lower end of the filter tube 122 open to the drain chamber 126 such that
the interior of the tube 122 is flushed downwardly by inlet pressure P, to the drain
chamber 126. Further rotation of the shaft 152 returns the disc valve member 140 to
the position shown in FIG. 3a and the sequence is repeated for another circumferential
adjacent set of tubes.
[0028] With reference to Table 1, the valving of the paddle valve 134 and disc valve
140 may be rotationally positioned with respect to each other to effect various
combinations or modes of backflushing as described therein.
Table 1
Mode Paddle Valve Disc Valve Drain Process
1 Filter inlet Filter tube open Traditional Back Wash
3a blocked open
2 Filter inlet Filter closed open Dry cycle no flow through tube
3b blocked then open and traditional Back Wash
3 Filter inlet Filter closed open Dry cycle/Traditional Back
3c blocked and and open Wash / and center flush
open
4 Filter inlet Filter closed open Dry cycle and center flush
3d blocked and and open
open
5 Filter inlet open Filter outlet open Center flush
open
[0029] Referring to FIGS. 4 and 5, alternate forms of the paddle valve which may be
employed for either paddle valve 68 or paddle valve 134 are shown in FIG. 4 and
denoted by reference numeral 150. An alternate form of the disc valve 70, 140 is
shown in FIG. 5 and denoted with reference numeral 152 as having a plurality of
elongated arcuate slots radially spaced formed therein and denoted by reference
numeral 154. Corresponding slots 72 are provided in the version of FIG. 1.
[0030] In the present practice, it has been found satisfactory to utilize about 150 to
about 600 of the tubes 42, 122; and, in one version 290 tubes are employed
[0031] The present disclosure thus provides a fluid pressure filtering system in which
a filter cartridge is disposed in a pressure vessel with a plurality of tubes of filter material
disposed between spaced headers dividing the pressure vessel into an inlet chamber,
an outlet chamber and drain chamber isolated from the inlet and outlet chambers.
Rotary valves disposed adjacent the inlet header and drain chamber header are
operated by a central shaft through a core tube in the cartridge which shaft is connected
to a motorized speed reducer upon energization of the motor. The rotary valve in the
inlet chamber selectively progressively closes the inlet end of the filter tubes while the
rotary valve in the drain chamber opens the interior of the tubes to drain at atmospheric
pressure. The drop in fluid pressure in the drain chamber causes on the discharge
pressure outlet side of the filter tubes to create a negative differential pressure across
the filter tubes creating backflow through the filters which discharges trapped filter
material through the end of the tube to the drain chamber. The rotary valve on the inlet
side may then open the inlet of the tube to inlet pressure flushes the loosened trapped
filter material through the tube to the drain chamber.
[0032] The system of the present disclosure thus enables a filter cartridge having an
array of filter media tubes to be remotely selectively back flushed during service by
sequentially flushing the tubes with the rotary valving element to permit removal of
trapped filtered material in service without disrupting the filtering flow in the balance of
the filter array.
[0033] The exemplary embodiment has been described with reference to the
preferred embodiments. Obviously, modifications and alterations will occur to others
upon reading and understanding the preceding detailed description. It is intended that
the exemplary embodiment be construed as including all such modifications and
alterations insofar as they come within the scope of the appended claims or the
equivalents thereof.

CLAIMS:
1. A backwash system for a fluid filter comprising:
(a) a fluid pressure vessel having an interior wall surface and an inlet
and outlet communicating with the wall surface and adapted for connection respectively
to a fluid supply and discharge line;
(b) a removable filter cartridge having a plurality of tubular filter
elements having oppositely disposed open ends disposed in an array with a pair of
spaced tube sheets each disposed at one of opposite ends of the tubular filter elements
with the tube sheets having a centrally disposed tube extending therebetween, wherein
the cartridge is insertable in the pressure vessel;
(c) a shaft received through the centrally disposed tube and journalled
for rotation with respect thereto;
(d) an outlet chamber formed, upon insertion of the cartridge in the
pressure vessel, by sealing contact of the pair of tube sheets with the wall surface of the
pressure vessel, wherein the outlet communicates exclusively with the outlet chamber
and the opposite open ends of each of the tubular filter element are isolated from the
outlet chamber and an outer peripheral surface of each tubular filter element
intermediate the tube sheets is disposed in the outlet chamber;
(e) an inlet chamber defined by one of the pair of tube sheets and
portions of the wall surface of the pressure vessel and isolated from the outlet chamber
wherein one common inlet end of each of the tubular filter elements communicates
exclusively with the inlet chamber;
(f) a drain chamber defined by the other of the pair of tube sheets and
other portions of the pressure vessel interior wall and isolated from the outlet chamber,
the drain chamber having a drain port provided therein wherein an opposite common
open end of each of the tubular filter elements communicates exclusively with with the
drain chamber;
(g) a disc-like valve member having at least one aperture therein,
located for, upon rotation of the shaft, periodically blocking and opening respectively the
common open end of each of the filter elements communicating with the drain chamber;
(h) a paddle valve member disposed for rotation with the shaft in the
inlet chamber and spaced closely adjacent the common inlet open end of the filter
elements wherein the paddle member is configured and oriented such that upon rotation
of the shaft in one direction the inlet open end of each filter element is sequentially
blocked by the paddle member while the drain open end remains blocked, then
subsequently the drain end of the filter element is opened at the opposite common end
communicating the filter element with the drain chamber by the aperture in the disc-like
member then subsequently the paddle valve opens the inlet common end
communicating the filter element with the inlet chamber and the inlet fluid pressure
causes fluid flow through the respective tubular filter element and flushing of filtered
material to the drain; and,
(i) motor means operative upon energization for rotating the shaft.
2 . The system of claim 1, wherein the disc-like member includes a plurality of
radially spaced arcuate slots.
3 . The system of claim 1, wherein the filter elements have an inside diameter
of about 0.357-1 .0 inches (9.5 mm to about 25.4 mm) and a diameter of about 24 to
about 36 inches (609 mm to about 914 mm).
4 . The system of claim 3, wherein the annular chamber includes about 150
to about 600 filter elements.
5 . The system of claim 1, wherein the motor means includes a motor and
speed reducer connected to an end of the shaft extending externally of the pressure
vessel.
6 . The system of claim , wherein the pressure vessel includes a removable
lid.
7. The system of claim 6, wherein the motor means is mounted on the
removable lid and the shaft extends externally through the lid.
8 . A backwash system for a fluid filter comprising:
(a) a fluid pressure vessel having an interior wall with an inlet, outlet
and removable lid;
(b) a filter cartridge having a plurality of tubular filter elements with
oppositely disposed open ends disposed in array between a pair of spaced tube sheets,
the tube sheets having a core tube extending between;
(c) the cartridge being received in the pressure vessel with one of the
pair of tube sheets cooperating with the interior wall surface to define an inlet chamber
communicating with the inlet and with an inlet open end of each of the tubular filter
elements, the other of the pair of tube sheets cooperating with the interior wall surface
to define a drain chamber communicating with a drain end of each tubular filter element,
the drain chamber having a drain port, wherein an outlet chamber is defined
intermediate the tube sheets, the outlet chamber communicating with the outlet and
isolated from the inlet chamber and drain chamber;
(d) a shaft extending through the core tube of the cartridge and
journalled for rotation with respect thereto;
(e) a first rotary valve in the inlet chamber and a second rotary valve
disposed in the drain chamber, the first and second rotary valve each operably
connected with the shaft for rotation therewith;
(f) wherein upon rotation of the shaft in one direction, the first and
second rotary valves are operable with respect to each tubular filter element in one
revolution of the shaft to sequentially block the inlet open end of the tubular filter
element in the inlet chamber, with the second rotary valve blocking the drain open end
of the respective tubular filter element, maintain both inlet and drain open ends blocked
for a specified portion of the movement of the first and second rotary valve, then
subsequently the second rotary valve opens the drain end of the tubular filter element
permitting filtered material trapped in the tubular filter element to flow out therefrom to
the drain chamber and drain port and with subsequent rotation of the shaft the first
rotary valve opens the inlet end of the tubular filter element with the second rotary valve
maintaining the drain end of the tubular filter element open for inlet pressure flushing of
the tubular filter element to the drain chamber.
9. The system defined in claim 8, wherein the second rotary valve
sequentially opens the drain end of each of tubular filter elements before the first rotary
valve blocks the inlet end of the tubular filter element.