Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
  • B01D29/117—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements arranged for outward flow filtration
  • B01D29/118—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements arranged for outward flow filtration open-ended
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/88—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices
  • B01D29/90—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices for feeding
  • B01D29/902—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices for feeding containing fixed liquid displacement elements or cores
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/88—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices
  • B01D29/90—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices for feeding
  • B01D29/904—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices for feeding directing the mixture to be filtered on the filtering element in a manner to clean the filter continuously

Definitions

• the present invention relates to a filtration apparatus and a method for the separation of a fluid-solids mixture. More particularly, the invention provides means to allow a filtration process to continue for long periods, without clogging, by removing solids, including those of a biological composition, from the filter medium by turbulent flow and discharging these solids entrained in a small quantity of liquid and by periodic flushing.
• Filtration processes are widely used in industrial, chemical, municipal and agricultural systems. With the increasing adoption of drip- irrigation methods in agriculture, there has arisen a demand for better filtration of irrigation water. Improved filtration is essential for the satisfactory operation of drip-irrigation tubes, as these include fine passages and the clogging thereof with solid particles will result in failed crops. While in industrial environments a preventive maintenance program will include regular filter cleaning, in agriculture filters are likely to be widely dispersed and less likely to be serviced. Such conditions call for a filter unit of the type which can operate reliably for long periods without servicing.
• the input stream requiring filtration is directed to flow parallel to and along the face of the filter element through which it is passed in order to produce a filtrate of desired quality.
• some or most of the solids which are retained by the filtering process are swept to the far end of the filter, where they tend to accumulate.
• Deflectors are known which may be placed so as to increase the speed and force of the incoming parallel flow stream, and consequently its washing action.
• the present inventor disclosed a means to minimize accumulation of free or deposited solids in a filter by continually removing them without interrupting liquid flow through the filter, thus reducing costs associated with regular maintenance, with pressure loss, with filter shut-down and investment in backup filtration.
• the latter invention comprised pressure-reducing means ("bleed") in communication with the filter body, or within the latter, said bleed continuously discharging a small portion of the liquid flowing through the filter, together with solids retained by the filter element at a pressure substantially less than that within the filter, while the energy made available by the pressure reduction was either to be dissipated by means of the friction provided by the discharge path, or by using such energy for operating a hydraulic device placed within or without the filter.
• Various embodiments of the invention have greatly increased the working cycle of filters and improved quality of filtration by lessening eventual penetration of solids previously retained through the orifices of the filter screen, whether smaller than or similar in size to the orifices, and of larger particles worn down by repeated turbulence-induced particle- particle and particle-filter impact.
• clogging and eventual blockage of the screen could still be caused by indeterminate movement of particles close to the filter screen at its far end, by turbulent return of some retentions upstream in the filter and by a particularly heavy concentration of or by sudden spurts of solids in the incoming stream.
• Increasing discharge flow through the bleed means in order to cope with the latter, is sometimes not practical or economically efficient.
• volume reduction device VRD
• blow-out flushing as needed, as described in said U.S. Patents, is most effective, resulting often in working cycles of weeks, or even months without having to cease filtration.
• the invention may be exploited primarily to reduce to a minimum the amount of continuously discharged liquid.
• filters have been developed for such conditions, using screens which are cleaned by one or more of several methods including scraping, suction, brushing and jet-spraying. These are usually dynamic systems, requiring relatively expensive, often quite complex, hydraulic and electro-mechanical engineering, which in turn require suitable maintenance and other support.
• a further object of the present invention is to provide a filter for conditions in which the biological material in the liquid to be filtered is particularly problematic.
• Yet another object is to provide a filter embodying a static device which is technically simple and easy to make, convenient to operate and maintain and thereby cost-effective.
• TVRD modified TVRDs having textured turbulence-creating outer surfaces
• the incoming liquid stream flowing parallel to and between the filter screen and the TVRD interacts with the surface of the latter.
• the nature of the resulting turbulence is a function of the speed of flow and the configuration of the volume reduction device surface. While in most engineering applications surface roughness of flow channels is kept as low as possible, the present invention utilizes the known effect of surface roughness to deliberately create turbulent flow in the latter part of the filter. The turbulence will be less, or even non-existent, when water flow is relatively slow and much greater when flow is increased, e.g., during valve flushing. Furthermore, turbulence will depend on the degree of texturing at any particular point on the TVRD surface.
• few or no surface irregularities are placed on the TVRD at the inflow end of the filter.
• irregularities are gradually increased in number and/or depth, though not necessarily at a constant rate, towards the far end of the TVRD.
• turbulence is gradually and slightly increased along the screen to balance the gradual decline in flow speed due to the outflow through the screen and much more increased during flushing, when speed of flow is both increased and maintained along the full length of the screen and the TVRD.
• the present invention achieves the above objectives by providing a clog-resistant filter for separating solids from liquids of the type wherein said liquid is passed from a filter inlet through a circular-section hollow filter element, said filter being provided with means for the discharge of collected solids during filter operation.
• the filter comprises: a) a housing provided with an inlet for the liquid to be filtered and provided with a first outlet for filtrate and with a second outlet for liquid containing a high concentration of solids; b) a hollow filter element insertable into said housing, the internal side of said filter element being in fluid connection with said inlet and the external side of said filter element being in fluid connection with said first outlet; c) a volume reduction device inserted in said filter element and being of a size to occupy a major portion of the hollow of said filter element, said volume reduction device being provided with a textured turbulence- creating outer surface; and d) a pressure-reduction device in fluid connection with said second outlet and provided with discharge means for solids and for the liquid in which they are entrained; whereby solid particles reaching said second extremity are swept out into the pressure-reduction device and the filter may operate for extended periods without attention during which time clogging of the filter element is inhibited.
• a filter wherein said textured turbulence-creating outer surface is configured to allow laminar flow near said first outlet and to cause a relative greater turbulent flow near said second outlet.
• said textured surface is adapted to cause turbulent flow along the whole length of said filter element during filter flushing.
• a filter wherein said textured surface has surface projections.
• a filter wherein said textured surface has surface indentations
• a filter wherein said textured surface has a combination of both surface indentations and surface projections.
• the hollow filter element used in the present invention can be a single unitary perforated element, or formed from a stack of filtering rings.
• the present invention also provides for a four-step method of filtering solids from liquids, comprising the steps: a) flowing a solid-entrained liquid into a narrow flow passage formed between a filter element and a volume reduction device having a textured turbulence-creating outer surface; b) separating the solid constituent from said liquid by allowing said liquid to pass through said filter element while solid constituents are retained thereby; c) discharging liquid passing through said filter element through a first outlet conduit; and d) continually discharging at reduced pressure said solid constituents, together with a small quantity of entraining liquid through a second outlet.
• said method further comprises periodically discharging said solid constituents through a valve.
• a method for filtering solids from liquids comprising the steps: a) flowing a solid-entrained liquid into a narrow flow passage formed between a filter element and a volume reduction device having a textured turbulence-creating outer surface; b) separating the solid constituent from said liquid by allowing said liquid to pass through said filter element while solid constituents are retained thereby; c) discharging liquid passing through said filter element through a first outlet conduit; and d) periodically discharging said solid constituents through a valve.
• the concentrated solution leaving the filter during continual or periodic flushing can be passed either to a drain or to a storage tank.
• a drain or to a storage tank is advantageous when a contaminating fluid such as a fuel is being processed, and allows for inspection or analysis of the solid constituent, which is likely to provide indication of process variables requiring correction.
• the collected solid may have commercial value.
• a discharge valve for entrained solids is powered by the pressure-reducing means in a hydraulically operated mechanism as described in U.S. Pat. no. 3,862,035, the teachings of which are incorporated herein by reference.
• Discharge of liquid-entrained solids may be carried out continually and/or by periodic valve discharge, the shock of valve opening making a valuable contribution to dislodging cake from the surface of the filter element.
• FIG. 1 is a cross-sectional elevational view of a preferred embodiment of the filter according to the invention.
• FIG. 2 is a detail view of an embodiment arranged for organized turbulent flow
• FIG. 3 is a side view of a volume reduction device having regularly arranged projections and indentations
• FIG. 4 is a detail view of a TVRD provided with irregularly arranged indentations
• FIG. 5 is a side view of a TVDR with circumferential grooves.
• FIG. 6 is a side view of a TVDR having a helical groove.
• FIG. 1 a clog-resistant filter 10 for separating solids from liquids, of the type wherein a liquid is passed from a filter inlet 12 through a circular-section hollow filter element 14.
• Filter 10 is provided with means for the discharge of collected solids during filter operation.
• a housing 20, shown as a two-part assembly for convenience of access, is provided with an inlet 12 for the liquid to be filtered, with a first outlet 22 for filtrate and with a second outlet 24 for liquid containing a high concentration of solids.
• a hollow filter element 14 removably assembled in housing has a first extremity 26 where liquid first contacts filter element and a second extremity 18 furthest from first extremity 26.
• the internal side of filter element 14 is in fluid connection with inlet 12.
• the external side of element 14 is in fluid connection with first outlet 22.
• a volume reduction device 28 is inserted in the space inside the filter element 14, and is of a size and shape to occupy a major portion of said space.
• the outer surface of device 28 is provided with textured turbulence-creating projections 32.
• said projections 32 are arranged to cause turbulent flow along the length of filter element 14 during filter flushing, when liquid flows through both outlet ports 22, 24, or through either port 22 or port 24 alone, such flow helping to dislodge cake 30 from the inner surface of the filter element 14.
• a pressure-reduction device 34 such as that described in US Patent 3,862,035, the teachings of which are incorporated herein by reference, can be used in conjunction with the present invention, and such a device is attached in fluid connection with the second outlet 24, and is provided with discharge means for solids and for the liquid in which they are entrained.
• the device 34 has a discharge outlet 36.
• a sump 38 connected between second outlet 24 and the inlet 40 of pressure reducing device 34 may optionally be provided.
• a discharge valve 42 being hand or automatically operable is also connected to the second outlet 24.
• FIG. 2 there is seen a detail of a filter 44 similar to that described with reference to FIG. 1.
• the flow tends to be laminar. This laminar flow is beneficial in preventing large particles from being forced into, or through the filter element 52.
• turbulence is caused, particularly where there is a greater density of texturing. This is valuable in carrying solid particles for transfer through the second outlet port 24, seen in FIG. 1.
• the textured turbulence-creating projections 56 on the outer surface of the volume reduction body 58 are positioned and dimensioned to cause a designed , turbulent flow even near the second outlet port 24 where flow rates are naturally low during filter operation.
• Seen in FIG. 3 is the textured surface on the volume reduction device 54 formed by both surface projections 62 and indentations 63, regularly arranged in both pattern and distribution along the length of the TVRD.
• FIG. 4 illustrates the textured surface of the volume reduction body 66 formed by surface indentations 68, arranged in an irregular pattern.
• FIG. 5 there is depicted the textured surface on the TVRD 74 formed by a pattern of circumferential form 76.
• a given textured surface can be provided with projections, indentations or combinations thereof, said projections and/or indentations being regular or irregular in shape, size, pattern or distribution, and said projections can also be of helical or circumferential configuration in a manner complimentary to that shown with regard to the indentations shown in Figs. 5 and 6, to create regular and/or irregular turbulence, as desired.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Filtration Of Liquid (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=11069259

Family Applications (1)

Country Status (4)

Families Citing this family (3)

Citations (2)

Family Cites Families (3)

• 1996
  • 1996-09-02 IL IL11918296A patent/IL119182A/xx not_active IP Right Cessation
• 1997
  • 1997-08-26 WO PCT/US1997/016197 patent/WO1998009705A1/en not_active Application Discontinuation
  • 1997-08-26 EP EP97942454A patent/EP0938358A1/de not_active Withdrawn
  • 1997-08-26 AU AU44147/97A patent/AU4414797A/en not_active Abandoned

Patent Citations (2)

Non-Patent Citations (1)

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