Classifications

• • 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
  • B01D33/23—Construction of discs or component sectors thereof
• • 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
  • B01D33/70—Filters with filtering elements which move during the filtering operation having feed or discharge devices
  • B01D33/76—Filters with filtering elements which move during the filtering operation having feed or discharge devices for discharging the filter cake, e.g. chutes

Definitions

• This invention is related to a device for filtering a liquid sub ⁇ stance according to the pre-characterizing part of enclosed claim 1. Furthermore, the invention is related to a method for converting a drum filter into a disc filter according to the pre- characterizing part of enclosed claim 14.
• liquid substance occurring hereinafter is in- tended to comprise various liquids, suspensions et cetera con ⁇ taining constituents desired to be filtered away. Even if the in ⁇ vention in no way is restricted thereto, a preferred application of the invention is in connection with dewatering of fibre suspen ⁇ sions. As fibres, cellulose fibres are primarily in view.
• disc filters of the nature in question there are two main types rele ⁇ vant in this connection, namely a first according to the pre- characterizing part of claim 1 , in which the means for removal of the released material and being present between two adja ⁇ cent filter discs has the character of a chute, an upper end of which is designed to receive the material released and which is arranged to deliver, at its lower end, this material to a receiver, which as a rule is formed by a conveyor, for instance a screw conveyor, extending with its longitudinal direction substantially parallel to the axis of the rotor.
• the conveyor is in practise lo- cated under the container.
• a conveyor extend ⁇ ing along the axis of rotation of the inner rotor part, said con ⁇ veyor being arranged to intercept material released from the filter discs and remove the same at one end of the rotor and the container.
• This liquid spraying involves, however, necessarily an increased liquid content in the material filtered away, this being as a rule a considerable disadvantage.
• the requirement for de- signing the upper portion of the chute so as to be able to inter ⁇ cept material filtered away and released means in practice that the substance level in the container must be set to be relatively low, which involves a relatively low capacity, in particular in connection with the need for a relatively large axial distance between the filter discs.
• the arrangement of the chutes between the filter discs means that a particular inlet box must be arranged along the longitudinal extent of the container. The purpose of this inlet box is to distribute the arriving sub ⁇ stance to be filtered in a uniform manner along the filter discs of the rotor.
• the inlet box may, to achieve uniform distribution of the substance, comprise inlet sections opening between adja ⁇ cent pairs of filter discs.
• Such inlet box structures increase considerably the cost for the device in its entirety.
• the second main type of disc filter suffers from the disadvan ⁇ tage that it is a rather costly construction to arrange the longi ⁇ tudinal conveyor within the inner rotor part.
• this longitudinal conveyor tends to necessitate a relatively bulky design of the inner rotor part.
• the location of the conveyor in the inner rotor part complicates the formation of conduits for conveying the filtrate from the filter discs and makes the same more costly.
• This formation of conduits must, namely, be carried out in a ring shape externally of the con- veyor. Material falling towards the conveyor may, furthermore, arrive on the conduits.
• a further disadvantage common to the two main types de ⁇ scribed is that an interruption of operation or a breakdown as far as the conveyor is concerned puts the entire filtering device out of operation.
• Drum filters occur in large numbers.
• Drum filters are characterized by the configuration defined in the pre-character- izing part of claim 14. However, they suffer from the disadvan ⁇ tage that they have a rather low capacity. The capacity is con ⁇ siderably lower than for disc filters having a corresponding total machine size. It would be desirable to be able to convert such drum filters to disc filters with a reasonable cost investment. However, up to now such conversion would involve such high costs that it generally has been found to be preferable to re ⁇ place the drum filter in its entirety with a disc filter.
• the object of this invention is to develop the device according to the pre-characterizing part of claim 1 so as to achieve a filter device improved from the point of view of costs and/or capacity and/or safety of operation as a consequence of improvements as far as the means for removal of the released material which has been filtered away are concerned.
• This object is according to the invention achieved by providing the device with the features appearing from the characterizing part in the enclosed claim 1.
• the filter according to the in- vention may operate with higher incoming concentrations in the substance of the material to be filtered away.
• concentration may be within the interval 2-3%, i.e. considerably higher than what is possible today.
• the filter device according to the invention may be used for substances having a lower dewatering resistance than what is possible with prior disc filters having chutes between the filter discs. Such a lower dewatering resistance gives rise to thickening of the suspension in the container.
• the filter device may manage dewatering resistance value of 450-700 CSF.
• the filter device according to the in- vention gives a higher output concentration of the material, which has been filtered away, as a consequence of the fact that the drying time may be longer.
• the chutes must be located on that side of the inner rotor part where the filter discs leave the bath of substance, which means that the means for releasing the material, which has been filtered away, from the filter discs must be located to exert their releasing operation in an area above the chutes.
• the filter device in its en ⁇ tirety may be shorter, i.e. with a shorter container, inner rotor part et cetera.
• the invention aims at providing possibilities for ra ⁇ tional conversion of drum filters into disc filters according to that defined in the preamble of claim 14.
• This object is according to the invention achieved by carrying out the conversion method in accordance with that defined in the characterising part of claim 14.
• Fig. 1 is a diagrammatical, partly cut end view of the filter de ⁇ vice according to the invention
• Fig. 2 is a section view taken along the line ll-ll in Fig. 1 ;
• Fig. 3 is a detail view corresponding to the upper portion in Fig. 1 but illustrating an alternative embodiment
• Fig. 4 is a view taken in accordance with the view in Fig. 2 but illustrating only an upper portion of the alternative em ⁇ bodiment illustrated in Fig. 3;
• Fig. 5 is a diagrammatical view illustrating the basic construc ⁇ tion of a drum filter known per se.
• the filter device according to the invention will hereinafter be described as applied for dewatering of cellulose fibre pulp.
• the filter device comprises a container, which is generally de ⁇ noted 1 and which has an inlet 2 for the fibre suspension.
• This inlet 2 is arranged in a gable wall of the container 1.
• a duct leading to the inlet 2 is denoted 3.
• the container 1 has a lower part 4 having the character of a bowl, the upper part of which is closed by means of one or more covers or the like 5, which may be opened.
• a rotor generally denoted 6 is rotatably arranged in the con- tainer 1.
• This rotor comprises an inner rotor part 7 and a num ⁇ ber of outer disc like filter elements 8 orientated transversely to an axis of the inner rotor part 7. This axis coincides with the axis of rotation of the rotor.
• the disc-like filter elements 8 are orientated generally per- pendicularly to the axis of rotation of the rotor and the axis of the inner rotor part 7, it is pointed out that the expression "transversely" just used comprises also a certain deviation from such a perpendicular position.
• the individual disc-like filter element 8 extends in an annular configuration about the inner rotor part 7.
• This annular configuration is more specifically di ⁇ vided (see Fig. 1 ) into a number of filter sectors 9.
• Each of these filter sectors 9 comprises an outer filtration covering, which in Fig. 1 is indicated by the screen pattern at the top, and inner conduits (not illustrated) for conveying filtrate passing through the filtration covering 10 to one or more filtrate conduits 1 1 in the inner rotor part 7.
• each individual filter sector 9 comprises a pipe-like conduit section 12 for transferring the filtrate, i.e. the filtrated water, from the filter sector 9 in question into a respec ⁇ tive filtrate conduit 11 in the rotor part 7 via an opening 13 ar ⁇ ranged for the filter sector in question in a mantle 14 of the ro ⁇ tor part 7.
• the device comprises means 15 for releasing fibre material, which has been filtered away, and which has deposited on the filtrating covering 10.
• These releasing means 15 are here formed by spray nozzles arranged to separate, by means of suitable spraying of water or other liquid, the mat of material, which has been filtered away, from the filter sectors as these rotate by.
• the device comprises means 17 for removal of the released fibre material.
• the pipe-like conduit sections 12 form a spoke configuration between the filter sectors 9 and the inner rotor part 7, i.e. that there are open spaces between these individual spokes.
• These open spaces make it possible for the fibre suspension supplied within the container 1 to distribute it- self uniformly along the length of the container 1 not withstand- ing the fact that the suspension is supplied, in the embodiment illustrated, at one of the gables of the container.
• the fibre suspension may of course distribute itself within the con ⁇ tainer 1 through the slots occurring radially outwardly of the pe- ripheries of the filter element 8 and the inside of the container 1.
• the inner rotor part 7 has in practise the character of a central shaft, which in a suitable manner is journalled to rotate. It is in- dicated in Fig. 2 that the centre shaft 7 at one of its ends may comprise a shaft pin 18 mounted in a suitable bearing and cou ⁇ pled to a driving motor 20. At the other end, the centre shaft 7 is supported in bearings 21 contacting the outside of the mantle 17 of the centre shaft 7.
• the filtrate conduits 1 1 within the centre shaft 7 have the char ⁇ acter of sector shaped spaces mutually separated by means of substantially radially orientated partition walls 22 extending along the entire length of the centre shaft 7.
• the centre shaft 7 has a tubular core 23, against the mantle of which the partition walls 22 adjoin tightly such that the tubular core 23 forms radially internal delimitations of the fil ⁇ trate conduits 1 1.
• the tubular core 23 may have a varying diameter along the length of the centre shaft 7.
• the device is such that the tubular core 23 has its smallest diameter at 24, which is that end of the tubular core 23 which is located at that end of the centre shaft 7 where the filtrate passes out of the centre shaft in its axial di ⁇ rection.
• two outlets 25, 26 are pro- vided for filtrate.
• the outlet 25 is intended for a pre-filtrate (cloudy filtrate) whereas the outlet 26 is intended for a clear filtrate.
• At least the clear filtrate outlet 26 and pos ⁇ sibly also the pre-filtrate outlet 25 may have the character of fall tubes intended to establish a vacuum in a suction head, which is denoted 27 and which via a filtrate valve 28 communicates with the filtrate conduits 1 1 in the centre tube 7.
• the suction head 27 and the filtrate valve 28 are stationarily arranged and the latter includes a disc, which likewise is stationary and which comprises tight portions which are black in Fig. 1 , and in addi- tion, open portions which are sector shaped and which are indi ⁇ cated at 30 and 31 respectively.
• a disc which likewise is stationary and which comprises tight portions which are black in Fig. 1 , and in addi- tion, open portions which are sector shaped and which are indi ⁇ cated at 30 and 31 respectively.
• the device comprises further means 32 for cleaning the filter sectors after the same having been deliberated from deposited fibre material by means of the releasing means 15.
• the means 32 may have the character of spraying nozzles, for instance lo- cated on an oscillating carrier so as to efficiently sweep over the filter sectors.
• a partition 33 extending axially in relation to the rotor separates that upper area of the interior of the con ⁇ tainer, where the deposited fibre material is released from the filter sectors, from that area where spraying for cleaning pur- poses occurs by the means 32.
• the filter sectors 9 will, after having been cleaned by means 32, move downwardly into the suspension in the container 1 . Water will then flow through the filter covering 10 on the filter sectors and fibres will then get stuck on the covering. The water flows within the filter sectors via the conduits 12 and the openings 13 into the filtrate conduits 1 1 and further, within the sector 30 of the disc 29, out through the pre-filtrate outlet 25.
• the filter sectors When the filter sectors then move further, they arrive gradually with their fil ⁇ trate conduits 1 1 in the centre shaft 7 into the sector area 31 of the disc 29, which means that the filter sectors then are sub- jected to suction from the vacuum fall tube 26. This means ef ⁇ fective suction of filtrate through the filter coverings and depo ⁇ sition thereon of fibre material.
• the filter sectors On continued rotation of the ro ⁇ tor, the filter sectors will then pass up over the suspension level, which is indicated at 34, in the container 1. This means that the suction via the vacuum fall tube 26 will create an air flow through the filter mat on the filter sectors and further through the conduit sections 12 in through the filtrate conduits 1 1.
• the filter sectors 9 successively reach the releasing means 15, they are deliberated from the filter mats deposited thereon. The filter sectors 9 then pass to the cleaning means 32, whereupon the cycle is repeated.
• the present invention deals primarily with improvements with respect to the removal means 17. These are, as is most clearly apparent from Fig. 2, located between each pair of adjacent filter discs 8 and also externally of the filter discs located out ⁇ ermost on the centre shaft 7.
• each of the removal means 17 comprises a moveable transport member 35, which by means of a driving member 36 is driveable to displace the released fibre material substantially parallel to the plane of the filter discs 8 at an angle, preferably a substantially right angle, to the axis of rotation of the centre shaft 7.
• the transport member 17, see Fig. 1 is arranged to displace the material, which has been filtered away, to a location 37 situated exter ⁇ nally of the peripheries of the filter discs 8.
• the location 37 is situated externally of the container 1 .
• the transport member 35 extends preferably substantially hori ⁇ zontally.
• the transport member 35 extends above the axis of the centre shaft 7.
• the transport member 35 is intended to have moveable transporting portions located on either sides of a ver ⁇ tical plane which is parallel to and coincides with the axis of the centre shaft 7 and also with the axis of rotation thereof.
• the transport member 35 is in its entirety located above a hori- zontal plane, which forms a tangent to the uppermost portion of the centre shaft 7. In this connection it is preferred that the transport member 35 extends substantially parallel to and just above the level 34 of the suspension in the container 1.
• the transport member 35 is located (see Fig. 2) in a channel 38 and arranged to displace the material, which has been filtered away, along this channel.
• the channel 38 has side walls which rather closely adjoins to the adjacent filter discs 8 in an order to efficiently receive the material released from the filter sectors 9. It is preferable that each channel 38 at the bottom has a shape adapted to the shape of a transport member 35 and at the top has diverging side walls.
• the transport member 35 are located such that they have por ⁇ tions situated in that area of the container where the filter discs move up and out of the substance to be filtrated.
• the re ⁇ lease of material, which has been filtered away from the sub ⁇ stance, from the filter discs occurs so that the material adhering to the filter discs first passes the transport members 35 and then is released and falls down on the transport members.
• the filter discs reach into a cleaning area, in which cleaning is conducted by means of cleaning members such as those denoted 32.
• the transport members extend above and beyond the inner rotor part 7.
• An individual transport member 35 comprises a driving member 36 driving the transport member, said driving member being without driving connection with one or more further transport members 35.
• the meaning of this is that if an individual trans ⁇ port member 35 or the driving member 36 thereof is put out of operation due to need of service, maintenance or a breakdown, there should be at least one or some further transport members with unimpaired function, so that the filter device in its entirety may be operated further, although with a reduced capacity.
• each individual transport member 35 is in- tended to have its own driving member so that in case of a breakdown or need of service of an individual transport mem ⁇ ber, all other transport members may continue to operate with ⁇ out appreciably lowering the total capacity of the filter device.
• two or further transport members 35 may be driven commonly by one and the same driving member, so that a greater reduction of capacity of the filter device occurs when there is need of service and mainte ⁇ nance or when a breakdown occurs.
• the transport members 35 are arranged to transport the mate ⁇ rial, which has been filtered away, to a conveyor 39, adapted to convey the material received substantially along the axis of ro ⁇ tation of the centre shaft 7.
• the conveyor 39 re ⁇ ceives the material, which has been filtered away, at location 37, preferably as a consequence of the transport members 35 delivering the material so that it may fall down into the conveyor 39.
• the transport member 35 is formed by a trans- port screw.
• This is preferably of the nature which does not have any core.
• the transport screw comprises a longitudinal centre cavity, which on rotation of the transport screw allows, in case of material accumulations, the trans ⁇ ported material to move over a thread portion of the transport screw. In this way occurrence of high counter pressures on in ⁇ terruptions in the feeding are avoided.
• the transport member 35 is in absence of at ⁇ tachment in the area of its inner end inside of the container so that, accordingly, the transport screw conveniently may be re ⁇ tracted perpendicularly to the longitudinal extension of the rotor out of the bowl 38 when replacement or service is required.
• the conveyor 39 comprises a transport screw arranged in a trough 40, which opens at the top for re ⁇ ceiving the material, which has been filtered away and which is discharged by the transport screw 35 at the extreme end of the channel 38.
• the presence of the transport members 35 between the individ ⁇ ual filter discs 8 ensures a very safe and efficient removal of the material, which has been filtered away, perpendicularly to the axis of rotation of the rotor.
• the actively moveable transport members 35 require a smaller axial space than the stationary chutes which have been used according to the prior art and provide, nevertheless, a more safe removal with a higher con ⁇ centration of the material removed.
• the variant according to Figs. 3 and 4 corresponds to the em- bodiment according to Figs. 1 and 2 with the exception that the transport member 35a here has the character of a transport belt of an endless type.
• This transport belt is laid around diverting members 41 , 42 in the form of rolls, rollers or the like and op ⁇ erates such that material, which has been filtered away and which falls down on the upper part of the transport belt is deliv- ered to the conveyor 39.
• guide mem ⁇ bers 43 in the form of plates or the like are adapted to guide material falling downwardly onto the upper part of the transport belt 35a.
• the transport belt 35a is preferably driven in the man ⁇ ner that the diverting member 42 which is the outer one with re ⁇ gard to the axis of rotation of the rotor is driven by a suitable driving member.
• the embodiment according to Fig. 3 and 4 is intended to correspond to the one previously de ⁇ scribed.
• a drum filter of a nature known per se is illustrated in Fig. 5, said drum filter comprising a container 44, an inlet 45 to the container for the suspension to be filtered, a drum 46, which is rotatable in the container and which has a peripheral filter man- tie 47, means 48, for instance in the form of a centre shaft of the drum, for discharging filtrate which has entered the interior of the drum, means 49 for deliberating the filter mantle from material, which has been filtered away from the suspension and a conveyor 50 for receiving and removing the material, which has been filtered away, along the axis of rotation of the drum 46.
• the filter mantle 47 is in ⁇ tended to be relatively smooth or otherwise of such a nature that material deposited on the filter mantle may be removed by means 49 in the form of doctor blades or similar.
• means 49 in the form of doctor blades or similar.
• other means 49 than doctor blades for instance spray nozzles, may be used for deliberating the filter mantle from material which has been fil ⁇ tered away.
• the present invention enables, by means of the basic structure described with assistance of Figs. 1-4, that a drum filter of the nature illustrated in Fig. 5 comparatively cost effectively may be converted to a disc filter, which due to a considerably increased filter area, gives rise to a considerably increased capacity.
• the rotatable drum 46 of the drum filter according to Fig. 5 is removed and this drum is re- placed by a disc filter rotor corresponding to the rotor 6 accord ⁇ ing to the embodiment described, said disc filter rotor compris ⁇ ing a plurality of disc like filter elements 8 arranged about an inner rotor part 7.
• a moveable transport member 35 or 35a is arranged in anal- ogy to that described hereinabove, said transport member being arranged to receive material, which has been filtered away and which has been deposited on the filter elements 8 and released therefrom by means of releasing means, such as those denoted 15 in Figs. 1 and 3, included in the disc filter, said transport member being driveable by means of a driving member such as that denoted 36 in order to displace the material received sub ⁇ stantially parallel to the filter elements 8.
• the conversion described means that very important parts of the existing drum filter may be maintained, namely its container 44, the arrangement in connection with the suspension inlet 45 and also the discharge conveyor 50 for the fibre material to be transported away. Last, but not least, large parts of the filtrate discharging system for the drum filter proper may be maintained and connected to the newly installed disc filter rotor.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Filtration Of Liquid (AREA)
• Filtering Materials (AREA)
• Grinding-Machine Dressing And Accessory Apparatuses (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20398515

Family Applications (1)

Country Status (7)

Cited By (4)

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Citations (2)

Family Cites Families (6)

• 1995
  • 1995-06-02 SE SE9502046A patent/SE510475C2/sv not_active IP Right Cessation
• 1996
  • 1996-06-03 US US08/945,328 patent/US5951861A/en not_active Expired - Fee Related
  • 1996-06-03 CA CA002219004A patent/CA2219004A1/en not_active Abandoned
  • 1996-06-03 JP JP8536001A patent/JPH11505766A/ja active Pending
  • 1996-06-03 EP EP96917784A patent/EP0828544A1/en not_active Withdrawn
  • 1996-06-03 WO PCT/SE1996/000732 patent/WO1996038214A1/en not_active Application Discontinuation
• 1997
  • 1997-12-01 NO NO975535A patent/NO975535L/no not_active Application Discontinuation

Patent Citations (2)

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