US3724668A - Adjustable skip bridge valving mechanism for disc filter - Google Patents

Adjustable skip bridge valving mechanism for disc filter Download PDF

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Publication number
US3724668A
US3724668A US00110003A US3724668DA US3724668A US 3724668 A US3724668 A US 3724668A US 00110003 A US00110003 A US 00110003A US 3724668D A US3724668D A US 3724668DA US 3724668 A US3724668 A US 3724668A
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United States
Prior art keywords
vacuum
cake
sectors
filter
slurry
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Expired - Lifetime
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US00110003A
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English (en)
Inventor
H Ahlquist
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Erie Development Co
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Erie Development Co
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Publication date
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/15—Filters with filtering elements which move during the filtering operation with rotary plane filtering surfaces
    • B01D33/21—Filters with filtering elements which move during the filtering operation with rotary plane filtering surfaces with hollow filtering discs transversely mounted on a hollow rotary shaft
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/80—Accessories
    • B01D33/82—Means for pressure distribution

Definitions

  • each such disc being composed of a plurality of radially extending filter cloth-covered, (textile or metal), filtering sectors (paddles) the hollow interiors of which communicate with suction lines located within the hollow shaft.
  • the suction lines are independent from each other, and are connected each to a row of sectors (one from each disc) and terminate at one or both ends of the shaft with matched valve heads.
  • the shaft being rotatable and the valve heads stationary and connected to vacuum and air supplies, rotation causes the sectors of the discs to be successively dipped into a slurry (pulp) for cake deposition by vacuum application and rotationally lifted out of the slurry for dewatering (drying) by vacuum application and then removal of the filtercake by suitable means for capture and transportation away from the filter.
  • a slurry for cake deposition by vacuum application and rotationally lifted out of the slurry for dewatering (drying) by vacuum application and then removal of the filtercake by suitable means for capture and transportation away from the filter.
  • Scraper simply a blade that scrapes or shears the cake from the sector surface.
  • FIGS. l-9 inclusive The present invention will be described with particular reference to a series of FIGS. of drawing beginning with FIG. 10 and extending to FIG. 17 inclusive. This showing is prefaced by.a explanation of what occurs in the operation of a conventional disc filter as represented in FIGS. l-9 inclusive.
  • FIG. 1 represents a vacuum valve of a conventional vacuum disc filter
  • FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1;
  • FIGS. 39 inclusive sequentially represent the course of a revolution of the filter about the axis of the filter shaft, in which FIG. 3 shows the attitude of the filter at the moment when sector I is about to have the filtercake removed from the filtering surface;
  • FIG. 4 shows the attitude at the moment when the filter paddle of sector I is fully submerged in the slur-
  • FIG. 5 represents the situation at the moment that sector I is being lifted from the slurry
  • FIG. 6 shows the condition in which cake deposition has been completely stopped at sector I andthe leading edge of the sector already has begun to undergo drying
  • FIG. 7 shows-the attitude of the subject sector when filtrate starts to flow from the interior of the sector
  • FIG. 8 shows the condition at which the subject sector has traversed the most nearly ideal internal drainage phase
  • FIG. 9 represents a possible variant wherein bridging between vacuum ducts is reduced from the conventional
  • FIG. 10 represents the valve head of a vacuum disc filter in accordance with the present invention.
  • FIG. 11 is a cross-sectional view of the valve head shown in FIG. 10, taken on line IIIIII of FIG. 10;
  • FIGS. 12-17 inclusive parallel FIGS. 3-9 inclusive but differ therefrom solely in an exposition of the application of the principles of the present invention to the valve head of an otherwise conventional vacuum disc filter.
  • 1 10 represent a series of ten sector apertures
  • FIG. 1 shows a general form of vacuum valve (the opposite end of the filter shaft uses configuration of the opposite hand) with its inserted bridge blocking.
  • the extension or arc length of the bridge blocking depends on the filterability of the material as determined by bench test or experience. Its primary purpose is to limit the are time of cake formation and is obviously alterable but not adjustable.
  • FIGS. 3-9inclusive are used to explain the main action of the conventional machine and point out advantages and disadvantages.
  • the figures are elevated views from the disc side of the shaft-vacuum valve contact and emphasize the affect on a single row of sectors and indicate the subsequent effects occurring simultaneously on the other nine rows.
  • a portion of the involved sector, as well as the slurry or pulp level, is shown to provide a degree of relativity. The cycle will be started at the blow or cake removal position.
  • valve head (stationary portion) is positioned to provide filter cake release when the backing edge of the sector is horizontal, at which point the cake will fall clear of the. filter tube slots.
  • Standard practice dictates that the shaft tube be centered on the blow slot. [It has been judged that a better timing places the slot high to the shaft tubing exposure when the snap blow" air is applied-to minimize transportation of any accumulated filtrate back to the filter-cake]
  • the duration of the timed compressed air application is sufficiently short to permit full explosure of the blow port to the shaft tube.
  • Tube 1 With the assembled bridging of measured from the blow port, the subject row of sectors reaches this relative position at the moment the vacuum begins to be admitted to the sectors for the cake formation or pickup phase.
  • Tube 1 has transversed the bridged-off vacuum arc of contact, with which latter tubes 2, 3 and 4 are in contact. As indicated, tube 1 is commencing exposure to vacuum at this point, and cake formation does begin and advances at a rate commensurate with the disc speed, pulp solids, particle size, etc.
  • the subject row of sectors has advanced to full exposure to vacuum.
  • the size of the shaft tube and the hole circle" equates to 26 of rotation. It is evident that in this much advance, part of the leading edge of the sector has already parted from the pulp and no additional cake can be acquired or deposited on any portion not exposed to pulp with or without vacuum. This then represents the maximum to which the bridging can be advanced. It also helps to explain why the 130 or more extended bridging actually begins to produce wetter cake but not necessarily thicker (or, more) cake. With vacuum continuously applied (once started), and only the trailing edge exposed to pulp, the leading edge has thinner cake and the trailing edge acquires thicker cake.
  • the shaft tube in actuality becomes a horizontal launder at this point because it is or should not be full of filtrate. Draining a horizontal launder produces the least amount of filtrate by high slurry solids and provides the most time for drainage by operating at the lowest disc speed.
  • the purpose of this invention is to permit the use of optimum levels of those factors, as well as to provide independent control of quantity and moisture of filtercake to provide a means of adjusting to the many other variables which effect filtercake moisture and quantity; in part such as:
  • FIGS. and 11 show a general view of the skip bridge plate (the opposite end of the filter shaft again would use a configuration of the opposite hand) according to the invention.
  • the distinct design characteristic is involved in the two slots in the lower portion of the bridge plate.
  • the width of the slots must be less than the effective (allowance for worn or rounded edges) width of the solid spaces between the shaft tubes of the matching faces.
  • the lower port is the primary control point for cake deposition while the upper port is primarily used for a reapplication of vacuum under adverse condition when vacuum depreciates too rapidly before the sector has rotated enough to receive the full vacuum of the drying port. If the vacuum depreciates too much, a condition of cake slipping" occurs where the filtrate in the sector interior washes back through the sector face and the formed cake slips off into the slurry.
  • the subject (no. 1) row of sectors is again in position with the leading edge horizontal to permit cake removal to the bin below.
  • the blow porting is located high with respect to the tube to minimize the blow back of the filtrate that may accumulate in the shaft tubing.
  • the snap blow cake removal is used which has already been explained.
  • the shaft tube has just breached the pick-up port while the sector is totally submerged in the pulp. Due to fluid (gas) flow, the vacuum is applied to the sector row gradually; and with any chosen mechanical configuration, the rate of vacuum application would be dependent on shaft rotational speed. There are also interrelating effects on cake formation by such variables as slurry density, slurry temperature (filtrate viscosity), particle size, and so forth.
  • a throttling valve is introduced between the vacuum supply and the pick-up port to control cake thickness independent of those other forces.
  • the shaft tube has traversed the pick-up port and reentered a vacuum bridged portion while still at the totally submerged state. Though the cake formation applied vacuum is throttled, the sector has been exposed for an arc distance of twice the diameter of the shaft tube plus one width of the pick-up port, or approximately 62.
  • the skip bridge resulted from the desire to reduce the cake formation are time without increasing the differential in cake thickness as was occurring with extension of the standard vacuum valve bridging. It was affected by extending the vacuum bridging to the extreme point of the sector being totally out of the slurry and then skipping a portion of vacuum bridging at the lower or submerged level of the sector, thus the naming of the skip bridge.
  • the adjustable skip bridge provides controlled cake thickness independent of the disc speed and/or slurry density (within the limits of all variables and their interactions as previously noted) for the purpose of controlling the entrained moisture in the cake consistent with good balling (subsequent processing) and W1 permit use of variable disc speed specifically for control of production quantity.
  • valve head of the present invention may be installed at either end of the filter shaft.
  • a vacuum disc filter having a plurality of discs disposed in spaced relation along a rotatable hollow shaft each disc being composed ofa plurality of radially extending, filter media-covered filtering sectors whose hollow interiors communicate with suction lines located within the hollow shaft and extending to a valving mechanism at one end of said shaft, said valving mechanism consisting of a multi-ported vlave head in communication with vacuum lines and with compressed air lines, said valving mechanism being programmed to effect sucking in sectors which are immersed in slurry and sectors undergoing drying and to effect an application of air at superatmospheric pres sure in sectors withdrawn from slurry and about to be rotatably returned to such slurry, the improvement whereby overall dryness of filter-cake can be enhanced which improvement consists in that said valving mechanism includes a skip bridge valve head comprising (a) a stationary bridge plate having slots for a lower pick-up port and an upper pick-up port, a drying port and a snap blow port, and (b)

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Filtration Of Liquid (AREA)
  • Treatment Of Sludge (AREA)
US00110003A 1971-01-27 1971-01-27 Adjustable skip bridge valving mechanism for disc filter Expired - Lifetime US3724668A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US11000371A 1971-01-27 1971-01-27

Publications (1)

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US3724668A true US3724668A (en) 1973-04-03

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Application Number Title Priority Date Filing Date
US00110003A Expired - Lifetime US3724668A (en) 1971-01-27 1971-01-27 Adjustable skip bridge valving mechanism for disc filter

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US (1) US3724668A (cg-RX-API-DMAC10.html)
JP (1) JPS5320151B1 (cg-RX-API-DMAC10.html)
AU (1) AU475249B2 (cg-RX-API-DMAC10.html)
CA (1) CA999814A (cg-RX-API-DMAC10.html)
DE (1) DE2203657C3 (cg-RX-API-DMAC10.html)
FR (1) FR2123384B3 (cg-RX-API-DMAC10.html)
NO (1) NO135229C (cg-RX-API-DMAC10.html)
SE (1) SE381574B (cg-RX-API-DMAC10.html)
ZA (1) ZA72531B (cg-RX-API-DMAC10.html)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4075103A (en) * 1976-06-30 1978-02-21 Kane Alfred J Fabricated disc filter core
US5674396A (en) * 1994-12-13 1997-10-07 Andritz-Patentverwaltungs-Gesellschaft M.B.H. Rotary filter with a device for separating a solids/liquid mixture, particularly a pulp suspension
WO1999025456A1 (en) * 1997-11-13 1999-05-27 Beloit Technologies, Inc. Adjustable control valve system for rotating disc filter
US6419835B1 (en) * 1998-06-25 2002-07-16 Outokumpu Oyj Method for producing a filter cake
US11135534B2 (en) 2016-11-18 2021-10-05 Andritz Ltd. Modular shaft for disc filter

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2228214C1 (ru) * 2003-04-25 2004-05-10 Общество с ограниченной ответственностью Научно-производственная коммерческая фирма "Бакор-фильтр Керамика" Распределительная головка для вращающихся вакуум-фильтров
DE102021111464A1 (de) 2021-05-04 2022-11-10 Voith Patent Gmbh Ventilvorrichtung für einen Scheibenfilter

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3193105A (en) * 1961-02-06 1965-07-06 Improved Machinery Inc Continuous disc filter
US3471026A (en) * 1966-12-09 1969-10-07 Dorr Oliver Inc Continuous rotary disc filters

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3193105A (en) * 1961-02-06 1965-07-06 Improved Machinery Inc Continuous disc filter
US3471026A (en) * 1966-12-09 1969-10-07 Dorr Oliver Inc Continuous rotary disc filters

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4075103A (en) * 1976-06-30 1978-02-21 Kane Alfred J Fabricated disc filter core
US5674396A (en) * 1994-12-13 1997-10-07 Andritz-Patentverwaltungs-Gesellschaft M.B.H. Rotary filter with a device for separating a solids/liquid mixture, particularly a pulp suspension
WO1999025456A1 (en) * 1997-11-13 1999-05-27 Beloit Technologies, Inc. Adjustable control valve system for rotating disc filter
US6419835B1 (en) * 1998-06-25 2002-07-16 Outokumpu Oyj Method for producing a filter cake
US11135534B2 (en) 2016-11-18 2021-10-05 Andritz Ltd. Modular shaft for disc filter

Also Published As

Publication number Publication date
FR2123384B3 (cg-RX-API-DMAC10.html) 1975-02-07
DE2203657B2 (de) 1979-12-20
DE2203657C3 (de) 1980-08-21
NO135229B (cg-RX-API-DMAC10.html) 1976-11-29
CA999814A (en) 1976-11-16
JPS5320151B1 (cg-RX-API-DMAC10.html) 1978-06-24
FR2123384A3 (cg-RX-API-DMAC10.html) 1972-09-08
NO135229C (cg-RX-API-DMAC10.html) 1977-03-09
ZA72531B (en) 1973-03-28
AU475249B2 (en) 1976-08-19
SE381574B (sv) 1975-12-15
DE2203657A1 (de) 1972-08-17
AU3836872A (en) 1973-08-02

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