Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D36/00—Filter circuits or combinations of filters with other separating devices
  • B01D36/001—Filters in combination with devices for the removal of gas, air purge systems
• • 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
  • B01D33/44—Regenerating the filter material in the filter
  • B01D33/46—Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element
  • B01D33/463—Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element nozzles
• • 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
  • B01D33/44—Regenerating the filter material in the filter
  • B01D33/46—Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element
  • B01D33/466—Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element scrapers
• • 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
  • B01D33/58—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element
  • B01D33/62—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying
  • B01D33/66—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying by gases or by heating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2201/00—Details relating to filtering apparatus
  • B01D2201/28—Position of the filtering element
  • B01D2201/282—Filtering elements with a horizontal rotation or symmetry axis
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
  • B01D35/30—Filter housing constructions
  • B01D35/31—Filter housing constructions including arrangements for environmental protection, e.g. pressure resisting features

Definitions

• the f il tering takes place under pres sure or under vacuum or under a combination of pres sure and vacuum .
• the filter includes a vessle containing the suspension to a certain level and a space with gas positioned above the suspension, a substantially horisontal centre axle rotatably arranged in the vessle, filter discs arranged at a distance from each other along the centre axle substantially perpendicular to the axle, said filter discs consist of filter sectors having surrounding filter cloth and internal channels for filtrate and gas obtain during the filtering operation, connection means in the centre axle between the filter sectors and an outlet from the vessle, removal means for each filter disc arranged in the gas space for the removing filter cake on the filter cloth obtained during the filtering operation, and means for receiving the filter cake material removed by said removal means.
• connection means in the centre axle between the filter sectors and the outlet from the vessle consists of a number of channels corresponding to the number of filter sectors.
• the number of filter sectors for instance is 20, which often is the case, there are accordingly in the centre axle 20 channels meaning that the centre axle must be formed with relatively large diameter and also is complicated and expensive.
• connection means in the centre axle between the filter sectors and the outlet consists of only one channel common for filtrate and the gas from all filter sectors in the vessle.
• the centre axle consists of a tube, which means a still more simplified and cheaper manufacture.
• the configuration of the center axle with only one channel gives furthermore another essential advantage.
• a filtrate separator is connected to the center axle and arranged for separating filtrate and gas.
• This transition has been made by using a so called filtrate valve having a wear disk as sealing between the rotating center axle and outlet tube to the filtrate separator.
• the filtrated liquid which flows in the channels through the outlet is rather clean and wears less in the center of the wear disk and axle, while the outer portion of the sealing is in unfiltrated medium which forces its way in between the sealing surfaces and wear the sealing element at the periphery.
• the removal device consists of a doctor or so called scraper, which is arranged immediately above the suspension level where the filter sectors inmerge down into the suspension, i.e. at the end of the rotation of the filter sectors in the gas space.
• the scrapers are therefore positioned substantially horizontally. Such a positioning of the scrapers causes,
• the scraped-off material will shuffel over the scraper with accompanying risk for deposed on the scraper.
• this positioning of the scrapers means a limitation of the use of the filtering surfaces of the filter discs, since the suspension level in the filter vessle can not be positioned higher than the position for the scraper.
• the positioning of the scrapers furthermore means, that the receiving means for scraped-off material must be formed comparatively wide, at least in the upper part and then taper downwardly to a circular outlet, which results in the necessity of having a relatively large distance between the filter discs.
• the removal device consists of an essentially vertically
• scraper for removing at least an outer layer of the filter cake along an essentially vertical line for essentially vertically sliding and falling down of the scraped-off filter cake material along the scraper.
• Another advantage with the positioning of the scrapers according to the invention is, that the suspension level in the filter can drastically be raised so that the filtering surface can be optimally used resulting in high and optimal capacity for each filter disc.
• Another advantage with the positioning of the scrapers according to the invention is that by this a filter construction having considerably less distance between the filter, discs on the center axle has been made possible, which makes possible an essentially smaller filter dimension than earlier in order to obtain the same capacity.
• said receiving device consists of an essentially vertically arranged outlet pipe. Due to the form of the vertical scraper, this outlet pipe below the scraper can have smaller diameter than corresponding receiving device in previously known filters and this outlet pipe does not need to be conical. This contributes to above mentioned less distance between the filter disks.
• precoat layer Preferably only an outer layer of the filter cake on the filter cloth is by the scraper removed for each revolution of the filter discs and the remaining filter cake, so called precoat layer, serves beside the filter cloth as filter.
• This precoat layer becomes in course of time too tight and must be removed.
• a blow off of the entire precoat layer takes place by blowing air into one of the channels in the center axle via a filtrate valve arranged at the outlet end of the axle and the entire precoat layer from a sector falls off the filter cloth. This results in that a large amount falls at the same time down into the tapered receiving devices and results in great risk for clogging.
• the internal blowing causes also that the cloths of the sectors are blown up immediately ahead of the scraper resulting in great risk for the cloth to be damaged by the scraper.
• the precoat removal is preferably carried out by a substantially vertically positioned spray pipe for high pressure washing.
• the spray pipe is positioned immediately ahead of the scraper and the wash liquid is supplied to the wash pipe in a separate conduit.
• a device for intermittent washing of the filter cloth According to a preferred embodiment of the invention the device for said intermittent removal of the precoat layer and the device for the intermittent washing are one and the same device, which in a constructive point of view is advantageous.
• the filtering can be driven a longer time since the scraper can come closer to the filter disc without any risk that it will grip in and damage the filter cloth,
• the diameter of the filter discs can be decreased with maintained filtering surface owing to the fact that the center axle has less diameter
• the filtering surface of the filter discs can be used optimally since the suspension level can be raised in the filter vessle,
• the volume of the filter can compared with previously known filters of the kind in question and with at least as large capacity be made essentially less and to an essentially lower cost, wherein for instance the distance between each filter disc can be decreased with about 35% meaning also shorter center axle, the diameter of the vessle can be made
• fig. 1 shows a lateral view, partly cut-up, of a filter
• fig. 2 shows a vertical section of the filter
• fig. 3 shows in larger scale a view from above of certain elements included in the illustrated filter.
• the filter shown on the drawing which in this embodiment is a pressure filter, includes as previously known pressure filters a substantially cylindrical pressure vessle 1, a center axle 2 rotatably journaled in the pressure vessle and a number of filter discs 3 arranged at a distance from each other on the center axle.
• Each filter disc consists of a number of disc sectors (not shown), for instance having the configuration shown in US patent No. 4695381.
• the filter sectors consists of a surrounding filter cloth and interior channels which are connected to the center axle for discharging the filtrate and gas obtained during the filtering operation to a filtrate separator 4 for separating filtrate and gas.
• the gas is returned to the pressure vessle 1 via gas conduit 5 provided with a compressor 6.
• the filter indludes a removal device or scraper 7 for removing the filter cake 8 (see fig. 3) obtained on the filter cloth during the filtering operation, a device 9 for removing filter cake material on the cloth positioned inside scraped-off filter material, so called precoat layer, a device 12 for receiving the removed filter cake material and a device for washing the filter cloth.
• the filter vessle has furthermore an inlet 10 for supplying suspension and maintaining the
• the center axle consists of only one channel common for filtrate and gas from all filter sectors in the pressure vessle as distinguished from previously known filters where the filter axle has been formed with a channel from each filter sector.
• the center axle consists of only one cylindrically tube with connections to the filter sectors.
• connection 15 to the filtrate separator 4 is obtained compared with the comparatively complicated filtrate valves which are arranged at the center axles formed with several channels in previously known filters.
• the connection 15 is positioned outside the filter vessle adjacent the vessle but can also be positioned at another place, for instance inside the filter vessle.
• the connection 15 between the rotating center tube 2 and a tube 16 connected to the filtrate separator 4 is constructively simple and allows a simple sealing, preferably a mechanical sealing.
• the center axle it shall furthermore be mentioned that it can be manufactured with considerably less diameter than center axles including a number of channels as in previously known filters.
• the scraper 7 is substantially vertically arranged in the gas space above the suspension level, whereby scraped-off material falls in a controlled form from the scraper and does not load the scraper and furthermore the risk for scraped-off material to be built up on the scraper is eliminated.
• the scraper can preferably be somewhat inclined outwardly seen from the center axle 2.
• the receiving device 12 for the scraped-off material consists of a vertical cylindrical tube having less diameter than previously known receiving devices formed with a cone, whereby also the risk for scraped-off material to be built up in the receiving device is eliminated.
• This positioning of the scraper and the shape of the receiving device as a cylindrical tube means that the distance between the filter discs can be made essentially less than what has been earlier the case (for instance about 35% less).
• the positioning of the scraper also means that the suspension level in the filter can be essentially raised, whereby the filtration surface can be used optimally.
• the scraper 7 is adjustable about an axle 13.
• a substantially vertically arranged removing device combined with wash device is in form of a spray tube 9 arranged ahead of the scraper in the rotational direction of the filter discs and above the outlet pipe 12.
• the spray tube receives spray liquid from conduit 14.
• Sprayed-off material falls herewith controlled down into the tube 12 and in an adapted amount per time unit. Moreover, the risk for the filter cloth on the filter discs to be damaged by the scraper is eliminated as distinguished from what is the case in previously known filters where the removal of the precoat layer takes place by blowing from inside outwardly through the filter cloth.
• filter discs and filter sectors the following advantages are obtained in a filter according to the invention.
• the number of filter sectors can be limited to what is possible to insert in the filter through assembly openings to the filter vessle and a small number of filter sectors per filter disc means small manufacture and assembly errors and that more straight sectors can be manufactured.
• the diameter of the filter discs can be decreased with maintained filtering surface owing to the fact that the center axle has less diameter.
• the filtering surface of the filter discs can be used optimally since the suspension level can be raised in the filter vessle. Thus, maximum capacity per installed filter surface is obtained.
• the precoat layer furthermore means that the scraper can scrape-off the filter cake closer to the filter cloths without risk for the scraper to grasp in the filter cloth.
• the volume can be considerably decreased with maintained capacity.
• the filter vessle can for instance have about 15% less diameter and filter discs have about 12% less diameter; particularly however the length of the filter vessle can be considerably decreased by the fact that the distance between two filter discs can be essentially decreased, for instance for about 35%, meaning also a shorter a center axle.
• a smaller vessle also means that thinner plate for the vessle can be used, The smaller size also gives shorter
• a filter for continous filtering under pressure has been shown on the drawing and described above. It shall, however, be noted that the filter can be a vacuum filter and also be constructed for filtering during both pressure and vacuum.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Filtration Of Liquid (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
• Separation By Low-Temperature Treatments (AREA)
• Cyclones (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20375324

Family Applications (1)

Country Status (9)

Cited By (4)

Families Citing this family (1)

Citations (4)

Family Cites Families (2)

• 1989
  • 1989-03-13 SE SE8900881A patent/SE463601B/sv unknown
• 1990
  • 1990-03-12 WO PCT/SE1990/000159 patent/WO1990010490A1/en not_active Application Discontinuation
  • 1990-03-12 DE DE90904970T patent/DE69005947T2/de not_active Revoked
  • 1990-03-12 CA CA002027565A patent/CA2027565C/en not_active Expired - Lifetime
  • 1990-03-12 BR BR909005740A patent/BR9005740A/pt unknown
  • 1990-03-12 JP JP2505009A patent/JPH03505545A/ja active Pending
  • 1990-03-12 AU AU53367/90A patent/AU632557B2/en not_active Ceased
  • 1990-03-12 EP EP90904970A patent/EP0414879B1/en not_active Revoked
  • 1990-11-13 FI FI905604A patent/FI92474B/sv not_active Application Discontinuation

Patent Citations (4)

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