Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F1/00—Wet end of machines for making continuous webs of paper
  • D21F1/66—Pulp catching, de-watering, or recovering; Re-use of pulp-water
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
  • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
  • D21D5/02—Straining or screening the pulp
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
  • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
  • D21D5/02—Straining or screening the pulp
  • D21D5/06—Rotary screen-drums
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F1/00—Wet end of machines for making continuous webs of paper
  • D21F1/66—Pulp catching, de-watering, or recovering; Re-use of pulp-water
  • D21F1/80—Pulp catching, de-watering, or recovering; Re-use of pulp-water using endless screening belts

Definitions

• the present invention relates to methods and apparatuses for the recovery of fibers from suspensions containing long fibers, medium fibers, fine short fibers, contaminants and liquid carrier.
• Background of the Invention In the prior art, it is well known that suspensions containing long fibers, medium fibers, fine short fibers, contaminants and liquid carrier may be separated in order to recover at least a portion of the fibers and fine fibers contained therein.
• a drum washer 100 there is shown in Figure 1 such a prior art device known as a drum washer 100.
• a filtration drum 102 rotates within a vat 104, containing a feed suspension 106 of fibers and contaminants suspended in a fluid medium such as water.
• the feed suspension 106 may also be sprayed onto the surface of the drum 102 as by nozzle 108 by a different prior art device known as a FLUIDIZED DRUM WASHERTM (a trademark of Celleco Hedemora, Inc. of Lawrenceville, Georgia) .
• the drum 102 is driven in direction 107 such as by a motor driven gear 109 which engages a toothed wheel and/or belt drive 111 attached to the drum 102.
• the drum 102 is supported by an axle 113.
• the drum 102 can be rotated in direction 107 through the vat 104 and through the feed suspension 106 contained within the vat 104.
• the drum 102 is porous with the pore size being selected to be larger than the size of typical contaminants, but smaller t h a n the fibers sought to be recovered.
• the operation of hydrostatic pressure will cause fibers to be retained on the outer surface 110 of the drum 102 as a second fraction 112, while contaminants and the fluid medium will pass through the outer surface 110 of the drum 102 to form a first fraction 114 within the interior 116 of the drum 102. This process will continue with the second fraction 112 forming an ever thickening mat on the outer surface no of the drum 102.
• This mat will further serve to retain fine fibers in the second fraction 112, while contaminants continue to pass into the interior 116 of the drum 102 to form the first fraction 114.
• this process results in the loss of some fine fibers, which undesirably reduces the tonnage yield of the fiber recovery process.
• fine fibers as well as contaminants pass through the filter material and into the first fraction 114, whereas where a mat has formed, the mat serves to trap fine fibers while the contaminants pass through the mat and filter material.
• FIG. 2 A different prior art embodiment of a fiber recovery system is shown in Figure 2.
• an endless belt 200 is provided on conveyor rollers 202.
• the belt 200 is made of a porous filter material which has a pore size selected to retain fibers on the surface of the belt 204, while allowing contaminants and liquid to pass through.
• a suspension containing fibers, fine fibers and con t aminants provided in a liquid medium is sprayed, or otherwise deposited onto the surface of the belt through a head box. Fine contaminants and the liquid carrier will pass t h roug h t h e belt 200 due to the action of gravity to form a first fraction 208 in a vat 210.
• the loss of fine fiber results in a reduced yield of usable fiber in the recovery process; thus decreasing the overall efficiency of the recovery process.
• the lost fiber must be addea from other sources which increases the costs of the recovery process.
• the loss of fiber results n an overall lower recycling efficiency which results in a greater volume of waste, or a greater use of raw natural resources; both such results are contrary to the goals of recycling and virgin pulping processes.
• the feed suspension is provided to a first filter which separates the feed suspension into first and second fractions.
• the first fraction consists of fine fibers, contaminants and liquid carrier which have passed through the first filter.
• the second fraction consists of fibers, fine fibers and liquid carrier which have been retained on the surface of the first filter.
• the second fraction is then removed from the first filter for further processing or use in the paper-making process.
• the first fraction is then provided to a second filter for separation into third and fourth fractions.
• the third fraction consists of fine fibers and liquid carrier which do not pass through the second filter.
• the fourth fraction consists of contaminants and liquid carrier which pass through the second filter.
• the fourth fraction typically constitutes a waste stream and is disposed of in an appropriate manner.
• the third fraction represents fine fibers which would otherwise have been lost in the production process.
• the third fraction is then returned to the first filter at a location wherein the second fraction has formed.
• the fiber mat which forms the second fraction assists the first filter in retaining the fine fibers present in the third fraction while the liquid carrier passes through the second fraction and first filter and into the first fraction once again.
• the first filter may be a Fluidized Drum WasherTM, a belt thickener, screw press, any type of dewaterer, bowscreen, pressure or gravity screen, hydrocyclone, or a variety of screen type filters.
• the second filter can also be selecte d from the same previously listed group of filters as the first filter or may be a SPRAYDISCTM filter manufactured by Celleco Hedemora of Lawrenceville, Georgia, U.S.A.
• the second fraction is provided to a third filter, or dewaterer, and is separated into fifth and sixth fractions.
• the sixth fraction consists of fibers, fine fibers and a portion of the liquid carrier that had remained in the second fraction.
• the fifth fraction consists of fine fibers and liquid carrier.
• the fifth fraction is added to the first fraction prior to introduction of the first fraction into the second filter. In this manner, any fine fibers present in the fifth fraction are recovered during processing of the first fraction by the second filter.
• the second filter is provided at an elevation above that of the first filter.
• the first fraction exits the first filter and drains, by force of gravity, into a tank positioned at an elevation below that of the first filter.
• the discharge from this tank is then provided to a pump which pumps the first fraction to the second filter.
• a conduit leading from the second filter to the first filter provides a pathway for the third fraction to flow, by force of gravity, to the first filter which is lower in elevation than filter 2.
• the second filter is provided at an elevation below that of the first filter.
• a conduit directs the first fraction, which flows by force of gravity, from the first filter to the second filter.
• the third fraction then flows by force of gravity to a tank disposed at an elevation lower than that of the second filter. The discharge of this tank is provided to a pump, which then pumps the third fraction through a conduit to the first filter.
• the first fraction flows by force of gravity to a tank positioned at an elevation lower than that of the first filter.
• the discharge of this tank is provided to a pump which pumps the first fraction through a conduit to the second filter.
• the third fraction flows by force of gravity through a conduit to a second tank which is positioned at an elevation lower than that of the second filter.
• a second pump is provided at the discharge of the second tank to pump the third fraction through a conduit to the first filter.
• the re ⁇ entry location of the third fraction into the first filter is controlled.
• the third fraction is reintroduced below the level of feed suspension in a vat in which the first filter is disposed.
• the third fraction flows through a nozzle directed to the first filter at a location whereupon a mat o f t h e second fraction has formed.
• the third fraction is reintroduced to the f irst filter a t locations above and below the level of f ee d suspension.
• nozzles direct the flow of the third fraction towar d t h e first filter.
• Figure 2 is a cross-sectional diagram of a prior art belt thickener
• Figure 3 is a block diagram of a system for the recovery of fine fibers
• Figure 4 is a block diagram of a system for the recovery of fine fibers incorporating a dewaterer
• Figure 5 is a cross-sectional diagram showing the components of the present invention, wherein a Fluidized Drum WasherTM is utilized;
• Figure 6 is a cross-sectional diagram showing the components of the present invention, wherein a belt thickener is utilized;
• Figure 7 is a side, cross-sectional view of a SPRAYDISCTM filter used in the present invention
• Figures 8 - 11 are a cross-sectional views of modifications of a fluidized drum washer used in various embodiments of the present invention
• Figures 12 - 14 are a block diagrams showing flow control components used in various embodiments of the present invention.
• Detailed Description of the Preferred Embodiments As was described in the previous sections, the use of drum washers, disc washers, belt recovery systems, pressure or gravity screen, hydrocyclones, screw or belt presses, dewaterers and a variety of other methods to separate fibers from fine contaminants and water are well known in the art.
• a waste stream consisting of fine contaminants and water is formed during the separation process.
• a medium is used to separate the fibers from the fine contaminants and a portion of the water used to transport the material.
• the medium will consist of a mesh or a porous material having a mesh or pore size selected to retain the fibers while allowing the liquid carrier and fine contaminants to pass therethrough.
• a feed suspension is first introduced to the medium, it is directed to the bare, or submerged, medium and, in addition to the fine contaminants and the liquid medium, smaller fibers will pass through the medium and become part of the waste stream.
• the mat itself acts as a filter material as well as the medium and fine fibers typically will be retained in the mat, while the fine contaminants and liquid will continue to pass therethrough.
• FIG. 3 shows a block diagram of a system use d to practice the present invention.
• a first filter device 300 separates a feed suspension (shown as an input to the filter device 300 on line 302) into a first fraction (shown exiting the filter device 300 on line 304) and a second fraction (shown exiting the filter device 300 on line 306) .
• the first fraction consists of the liquid medium, fine contaminants and fine short fibers not retained in the second fraction.
• the second fraction consists of long fibers and medium fibers retained by the first filter device and fine fibers which are either retained by the first filter device itself or the first filter device in cooperation with the second fraction formed thereon.
• the second fraction leaves the first filter device 300 on line 306 for further processing and use.
• the further processing may include additional washing, dewatering, bleaching or, ultimately, use in the paper making process.
• the first fraction on line 304 is directed to a second filtering device 308 for recovering fibers from the first fraction.
• the primary consideration in selection of the two filtering devices 300 and 308 is the nature of the material to be separated and the nature of the input material.
• the first filter device 300 would probably be selected with a filter medium that has a larger mesh, pore size, hole or slot than that of the second filter device 308, because the input material to the first filter device 300 will include larger material than the first fraction will contain.
• a fine mesh, pore size, hole or slot were selected for first filter device 300, clogging could occur which would reduce the filtering and washing efficiency.
• the second filter device 308 could have a smaller mesh or pore size to allow the recovery of finer fibers while still allowing the passage of fine contaminants and liquid.
• the second filter device 308 separates the first fraction into third and fourth fractions.
• the third fraction exits the second filter device on line 310 while the fourth fraction exits on line 312.
• the filter medium used in the second filter device 308 is selected so as to provide for the separation of a substantial percentage of fine fibers from fine contaminants and liquid.
• the fourth fraction will consist of contaminants and a portion of the liquid carrier medium
• the third fraction will consist of fine fibers and a portion of the liquid carrier medium (or will have liquid carrier medium added to allow for easy transport of the third fraction) .
• the fourth fraction constitutes a waste stream and may be further processed for discharge or may simply be discarded.
• the third fraction may be treated with a hydrocyclone, screen device, or chemical addition to enhance the stream prior to its return to the first separator, in any embodiment shown.
• the third fraction is then returned on line 310 to the first filter device 300.
• introduction of the third fraction into the first filter device 300 is carried out within a portion of the first filter device 300 upon which a mat of the second fraction has formed.
• the mat in cooperation with the filter medium will retain fine fibers present in the third fraction in or on the second fraction, while any remaining liquid medium or fine contaminants pass into the first fraction
• Figure 4 s a block diagram showing a modification of the preferred embodiment in which the second fraction is further processed.
• Various fractions are discussed in terms of their consistency to provide information as to the type of separation conducted at each stage.
• the feed suspension enters the first filter device on line 302.
• the feed suspension will have a consistency in the range of about 0.1% to 5%.
• the second fraction having a consistency in the range of about 4% to 30%, exits the first filter device 300 on line 304 and is provided to a processing device 316.
• This processing device 316 is typically a dewaterer of a type known in the art. Screw and belt presses, side hill screens, incline screws or paper machine formers could each be used as the processing device 316.
• the processing device 316 generates a fifth and sixth fraction from the second fraction. All of the dewatering devices described above exert some form of external pressure on the second fraction. As a result, fine contaminants, liquid medium (water) and some amount of fibers will form a fifth fraction in the nature of a liquid stream from the processing device 316.
• the sixth fraction consists of the remainder of the second fraction after processing by the processing device 316 and will typically have a consistency in the range of about 35%.
• the sixth fraction exits the processing device 316 on line 318 for further processing or use. For example the fibers present in the sixth fraction on line 318 may be bleached and then used in the paper making process, or they may be otherwise processed and used.
• the fifth fraction exits the processing device on line 320.
• the remainder of the system shown in Figure 4 operates in the same manner as was previously described with respect to Figure 3.
• the first fraction exits the first filtering device on line 306 to which line 320 is connected.
• the fifth fraction from the processing device 316 is added to the first fraction and the combined material is provided to the second filter device 308 for recovery of fine fibers.
• the second filter device 308 separates the input material (provided on line 306) into third and fourth fractions with the recovered fine fibers making up the third fraction and the contaminants and a portion of the liquid medium making up the fourth fraction.
• the third fraction is then returned via line 310 to the first filter device 300 , prefera b ly at a point where a mat ma d e o f th e secon d fract i on has formed, for further processing.
• the f irst filter i ng device 300 consists of a fiber d rum washer, which i s typical in the fiber recovery art.
• a fee d suspension 3 2 2 is provided to a vat 324, such as by spray nozzle 3 2 6 and condu i t 3 28.
• the feed suspension contacts a hollow drum 3 30 , the surface 3 32 of which is made of a filter medium.
• the d rum 330 is ma d e to rotate i n direction 329 such as by a motor 331 driving a toothe d gear 333 an d /or belt drive, which engages a toothe d gear 335 mounte d on the d rum.
• the filter medium of t h e surface 332 of t h e drum 330 i s selected to have a mesh or pore size which will reta i n fibers on the exterior of the drum, b ut allow fine contam i nants, and liquid to pass therethrough.
• the feed suspension 3 2 2 will contact the surface 33 2 of the drum 330 and will be separate d into components by the filter action of the drum. Fine contaminants, liqui d medium (water) and some fine fibers will pass into the interior of the drum 330 and form a first fraction 33 4. Fibers will b e retained on the surface 332 of the drum 330 an d form a secon d fraction 336, which typically manifests as a mat of fi b ers forming on the outer surface 332 of the d rum 330 .
• the formation of the second fraction 336 on the drum 330 also occurs when the feed suspension 322 is sprayed onto the outler surface 322 of the drum 330, such as through spray nozzle 326. It should be noted that material in the fee ⁇ suspension 322 passes through the filter medium of the drum 330 more easily on portions of the drum on which no mat has formed. On such portions of the drum 330, fine fibers may pass through the filter medium as will fine contaminants and liquid. By the operation of the feed suspension 322 being filtered by portions of the drum 330 upon which no mat of the second fraction 336 has formed, some amount of fine fibers will enter the first fraction 334. However, where a mat of the second fraction 336 has formed on the drum 330, the mat itself acts to filter the feed suspension and helps to retain fine fibers.
• the second fraction 336 is moved by motion of the drum 330 out of the vat 324 and into an exit conduit 338.
• the second fraction 336 is then further processed for use.
• the first fraction 334 is drawn out of the interior of the drum 330 through a take up 340 and provided as an output on line 306.
• the first fraction is then provided to a second filtering device 308, which separates the first fraction into third fraction 344 and fourth fraction 346.
• the second filtering device 308 may be a variety of filtering devices well known in the art.
• the second filtering device is a SPRAYDISCTM filter manufactured by Celleco Hedemora, Inc., of Lawrenceville, Georgia, U.S.A.
• the sole criteria for selection of the type of filtering device to be used as the second filtering device 308 the capability of separating fibers from fine contaminants and liquid.
• this second filtering device 308 will be selected to recover fine fibers from t h e first fraction while allowing fine contaminants and liquid to pass through.
• the fourth fraction 346 will consist of fine contaminants and liquid medium and exit the second filtering device on line 312.
• the fourth fraction 346 which is consi d ered a waste stream, is routed on line 312 for disposal or further processing.
• the third fraction 344 is provided as output on line 310 which returns the third fraction to the first filtering device 300.
• the second filtering device will consist of nozzles 348 which spray the first fraction 334 onto a filter disc 350.
• This filter disc 350 rotates so that material retained thereon is moved radially outward on the disc 350. As the retained material reaches the bottom of the arc of the disc 350, it is removed from the disc, such as by a mechanical scraper or a water stream. The retained material forms the third fraction 344. The material which passes through the disc 350 constitutes the fourth fraction 346.
• a more detailed description of a preferred second filter device 308 is provided with reference to Figure 7, below.
• the third fraction 344 is returned to the vat 324 for reintroduction into the feed suspension 322.
• a nozzle 352 reintroduces the third fraction 344 into the vat 324 at a point near the drum 330 on which a mat of the second fraction 336 has formed.
• the second fraction 336 in cooperation with the filter medium on the outer surface 332 of the drum 330 serves to act as a filter to retain the fine fibers present in the third fraction 344, which had previously passed through the outer surface 332 of the drum 330 and into the first fraction 334.
• any type of drum washer may be use d in the place of that described above as the first filter device 300.
• a preferred drum washer may be of the type described in U.S. Patent Application Serial Number 08/444,607, entitled “Fiber Suspension Thickener Having Improved Discharge Consistency,” filed on May 19, 1995, the entire disclosure of which is incorporated herein by reference thereto.
• T h e drum washer of that application includes a turbulence generator which disturbs the formed mat to improve the discharge consistency of the second fraction.
• a further embodiment, showing the use of a different type of first filtering device 300, is shown in Figure 6.
• the first filtering device 300 is a belt thickener as described with respect to the prior art in Figure 2 .
• Th e f eed suspension 322 is deposited onto an endless belt 356 of filter material from a head box.
• the second fraction 336 forms on t h e surface of the belt 356 and consists of a mat of retained fibers.
• the first fraction 334 passes through the belt 3 56 and is collected in a tank or vat 358.
• the first fraction 3 34 is collected by a take up 360 in the vat 358 and is carrie d via line 306 to a second filtering device 308.
• the first fraction is separated by t h e secon d filter device 308 into third fraction 344 and fourth fraction 346.
• the fourth fraction 346 is then provided as a waste stream output on line 312 for disposal or further processing.
• the third fraction 344 is provided on line 310 for return to the first filtering device 300.
• Line 310 is provided as an input to nozzle 360.
• Nozzle 360 is positioned at a point downstream of the head box, at a point over the belt 356 on which a mat of the second fraction 336 has already formed.
• the second fraction 336 in cooperation with belt 356, acts to recover fibers present in the third fraction 344, while any remaining fine contaminants and liquid medium pass through the mat of second fraction 336 and belt 356 to become again a part of the first fraction 334.
• the second fraction 334 is then exits the first filtering device via conduit 362 for further processing as was described above.
• the operation of the system shown in Figure 6 is identical to that shown in Figure 5.
• Figure 7 shows a preferred second filter device 308.
• the second filter 308 may comprise a filter which is sold by Celleco Hedemora, Inc., of Lawrenceville, Georgia, U.S.A., under the trademark SPRAYDISC.
• Figure 7 shows the components of this type of filter device in cross section.
• Support members 702 support a rotatable axle 70 .
• Attached to the axle 704 are filter discs 706, 708 and 710. These discs are made of a metal or synthetic support frame 712 which supports filter material 714.
• a motor 716 drives axle 704 which rotates as indicated by arrow 718.
• Nozzle support members 720 and 722 are likewise supported by axle 70 4 , but preferably are decoupled from the rotation of axle 704 so that the filter discs 706, 708 and 710 move relative to the nozzle supports 720 and 724.
• Nozzle supports 720 and 722 support a number of spray nozzles 724 which are directed toward the filter material 7 14 o f the filter discs 706, 708 and 710.
• the first fraction 33 4 is supplied to the nozzles 724 via line 306.
• the first fraction 334 is then sprayed onto the filter discs 706, 708 and 7 1 0 through nozzles 724. Fibers and fine short fibers present in the first fraction 334 are retained on the filter material 7 1 4 and drop to collection sumps 726 to form a third fraction 3 44 .
• the fine contaminants and a portion of the liquid carrier pass through the filter material 714 and collect in the interior of the filter discs 706, 708 and 710 to form a fourth fraction 346.
• the third fraction 344 is drawn from the sumps 726 and is output on line 310.
• the fourth fraction 346 is drawn from t h e interior of the discs 706, 708 and 710 and provided as output on line 3 12.
• the filter material 714 can be finer than the filter material used in the first filter device 30 0 ( previously described) since most of the coarse fibers will have b een remove d in the previous filtering step.
• the filter material 714 of the second filtering device may be finer without concern for clogging due to the accumulation of coarse fi b ers. In this manner, fine fibers which may have passed nto th e first f rac t ion dur i ng processing m the first filter device may b e recovere d b y the second filter device.
• F i gures 8 - 11 show alternative embodiments of the present invent i on with a variety of different first filtering d evices 300 an d points of reintroduction of the third fraction 344 . Not shown in these Figures is the processing of the first fraction 3 3 4 into the third and fourth fractions 3 4 4 , 346 . This processing may be identical to that described with respect to Figures 5, 6 and 7.
• Figure 8 shows a similar fiber drum was h er for t h e f irs t filter dev i ce 3 00 as was described with reference to Figure 5.
• a h ollow d rum 33 0 is prov i ded in a vat 324.
• a feed suspension 3 22 consisting of fibers, fine fibers, fine contaminants and liqui d carrier is introduced into the vat such as by conduit 3 2 8 an d nozzle 326 .
• the outer surface 332 of the drum 330 is made of an appropriate filter material.
• the drum 330 By operation of motor and gearing (shown in Figure 5 ) the drum 330 is caused to rotate as indicated by the arrow 329. By the action of hydrostatic pressure, fine contaminants and liquid carrier, along with some portion of fine fibers, are drawn into the interior of drum 330 to form a first fraction 33 4. Concurrently, a mat of fibers forms on the outer surface 33 2 of the drum 330 to form a second fraction 336.
• the first fraction 334 exits the drum 330 through take up 340 and is output on line 306.
• the second fraction 336 is provided to conduit 338 for output.
• the first fraction is separated into third an fourth fractions by a second filter device (shown in Figure 3).
• the third fraction 344 consists of fine fibers and liquid carrier, while the fourth fraction represents a waste stream of fine contaminants and liquid carrier.
• T h e thir d fraction 344 is returned to the first filter device 3 0 0 on line 310, which supplies two nozzles 352 and 35 4 with the third fraction 344.
• One nozzle 352 is provided in the vat 3 2 4 and is directed to a portion of the drum 330 upon which a mat of the second fraction 336 has already formed.
• the second nozzle 35 4 is directed to spray the third fraction 3 44 directly onto t h e ou t er surface 332 of the drum 330 at a location upon which the fee d suspension 322 has already been sprayed on the drum 330 through nozzle 326.
• FIG 9 shows a further alternative first filtering device 300.
• This first filtering device 300 is an example of a drum washer which forms a mat over the top of the drum 330 as opposed to underneath.
• the drum 330 is caused to rotate in the direction of arrow 802 as by a motor and suitable drive gearing (shown in Figure 5) .
• the outer surface 332 of the drum is covered with a suitable filter material as was previously described.
• Feed suspension 322 is provided to a vat 804 such as b y a nozzle 806. It should be noted that t h e nozzle 806 coul d b e directed to spray the feed suspension 322 directly onto the drum 330 .
• first fraction 334 is drawn out of the drum 330 by take up 340 and provided as output on line 3 06.
• a mat consisting of fibers forms on the outer surface 332 of the drum 330 to form a second frac t ion 336 .
• This second fraction 336 is then provided to an exit con d uit 338 f or further processing or use.
• the first fraction 334 is drawn off from the first filtering device 300, it is provided on line 306 for processing by a second filtering device (shown in Figure 3) for separation into third and fourth fractions.
• the third fraction consists of fine fibers and liquid carrier while the fourth fraction consists of fine contaminants and liquid carrier, while the fourth fraction comprises a waste stream which may be further processed or discarded.
• the third fraction 3 4 4 is returned to the first filter device 300 on line 31 0 .
• Line 310 feeds a nozzle 808 which is positioned to spray the third fraction 344 onto the drum 330 at a point whereupon a mat of the second fraction 334 has previously formed.
• FIG 10 shows yet another first filter device 300 in which a mat of second fraction 336 forms on the underside of a drum 330; however, in this case, the mat does not form below the level of liquid in a vat.
• a drum 330 having an outer surface 332 covered with an appropriate filter material rotates in the direction of arrow 810; the drum is driven by a motor with appropriate gearing and coupling (shown in Figure 5) .
• the feed suspension 322 is sprayed onto the drum 330 by nozzles 812 and 814 and, thus, is provided to the outer surface 332 of the drum 330 and to a vat 816.
• a second fraction 336 consisting of fibers forms on the outer surface 332 of the drum 330 and is moved by the motion of the drum to an exit conduit 818 for further processing or use.
• the first fraction is drawn off by take up 340 and is provided on output on line 306.
• first fraction 334 is drawn off from the first filtering device 300, it is provided on line 306 for processing by a second filtering device (shown in Figure 3) for separation into third and fourth fractions.
• the third fraction consists of fine fibers and liquid carrier while the fourth fraction consists of fine contaminants and liquid carrier.
• the fourth fraction comprises a waste stream which may be further processed or discarded.
• the third fraction 344 is returned to the first filter device 300 on line 310.
• a nozzle 820 is fed from line 310 and is positioned so as to deposit the third fraction 344 into the vat 816 at a position whereupon a mat of the second fraction 336 has already formed.
• the mat of second fraction 336 in cooperation with the filter material on the outer surface 332 of the drum 330, serves to retain fine fibers present in the third fraction 344.
• Figure ll shows an embodiment of a first filter device 300 similar to that described with respect to Figure 10.
• the feed suspension 322 is sprayed onto the outer surface 332 of a drum 330 which is covered with filter material by nozzles 819 and 821. Fine contaminants, liquid carrier and some fine fibers pass through the filter material and into the interior of the drum 330 to form first fraction 334. Fibers present in the feed suspension 322 are retained on the outer surface 332 of the drum 330 to form a second fraction 336.
• a vat 826 contains the second fraction 336 which does not remain on the surface 332 of the drum 330 during its rotation.
• the first fraction is drawn out of the interior of the drum 330 by take up 340 and is provided as output on line 306.
• first fraction 334 Once the first fraction 334 has been drawn off from the first filtering device 300, it is provided on line 306 for processing by a second filtering device (shown in Figure 3) for separation into third and fourth fractions, which have been described previously.
• the third fraction 344 is returned to the first filter device 300 on line 310 which feeds a nozzle 82 8 .
• This nozzle 828 is positioned so as to deposit the third fraction 344 into the vat 826 at a position whereupon a mat of the secon d fraction 336 has already formed.
• the mat of secon d fraction 336 in cooperation with the filter material on the outer surface 332 of the drum 330, serves to retain fine fi b ers present in the third fraction 34 4 .
• FIG. 12 - 14 block diagrams of preferred implementations of the above describes systems are described.
• the block diagrams of Figures 12 - 1 4 are designed to show the location of necessary auxiliary devices such as tanks and pumps and the relative elevations of components to attain the implementation the above described embodiments with the desired flow characteristics.
• Figure 12 shows an embodiment of the present invention wherein gravity flow and pumping is combined to cause the various fractions to flow in desired paths.
• the feed suspension is provided to a first filter device 300 on line 302.
• the source of the fee d suspension is preferably elevated above the first filter device 3 0 0 so that gravity will provide the necessary impetus for flow into the first filter device.
• the first filter device 30 0 separates the feed suspension into first and second fractions as has been described.
• the second fraction exits the first filter device 300 on line 304 for further processing or use.
• the first fraction exits the first filter device 300 on line 306a and empties into a tank 900 situated at a relative elevation lower than that o f the first filter device 300.
• gravity provides the flow of the first fraction through line 306a to the tank 900.
• a d ischarge located at the bottom of the tank directs the second fraction to a pump 902 which then pumps the second fraction through line 3 0 6b to the second filter device 308.
• the second filter device 3 0 8 is positioned at a relative elevation higher than the first filter device 300.
• the second filter device 308 separates the second fraction into third and fourth fractions.
• the fourth fraction exits the second filter device 308 through line 312 for disposal or further processing; the fourth fraction may flow either by gravity, or a pump external to the second filter device 308.
• the third fraction exits the second filter device 308 on line 310 and flows by gravity to the first filter device 300, where it is processed as was previously described.
• Figure 13 shows a different combination of gravity feed and pumping.
• the feed suspension 302 is provided to the first filter device 300, either under a gravity feed or through pumping.
• the first filter device separates the feed suspension into first and second fractions and the second fraction exits the first filter device on line 304 for further processing or use.
• the first fraction exits the first filter device 300 under the influence of gravity on line 306 where is proceeds to the second filter device 308, which is positioned at a relative elevation lower than that of the first filter device 300.
• the second filter device 308 separates the first fraction into third and fourth fractions as was previously described and the fourth fraction exits the second filter device 308 on line 312, either under the influence of gravity or with the use of an external pump.
• the third fraction exits the second filter device on line 310a under the influence of gravity and is deposited into a tank 904 situated at a relative elevation lower than that of the second filter device 308.
• the third fraction is discharged from the tank and provided to a pump 906 which pumps the third fraction along line 310b to the first filter device 300 where it is processed as was described previously.
• Figure 14 shows an embodiment employing two sets of tanks and pumps.
• the feed suspension enters the first filter device 300 on line 302.
• the first filter device 300 separates the feed suspension into first and second fractions and the second fraction exits the first filter device on line 304 for further processing or use.
• the first fraction exits the first filter device on line 306a and empties into a tank 908, which is preferably positioned at a relative elevation lower than the first filter device 300 so that gravity will cause the first fraction to flow through line 306a.
• the first fraction is discharged from the tank 908 and provided to a pump 910 which pumps the first fraction along line 306b to the second f ilter device 308.
• the first fraction is separated into third and fourth fractions and the fourth fraction exits the second filter device 308 on line 312 for further processing or disposal; the fourth fraction may flow on line 312 either through the force of gravity or by a pump external to the second filter device 308.
• the third fraction exits the second filter device 308 on line 310a and empties into a tank 912, which is preferably positioned at a relative elevation lower than the second filter device 30 8 so that the third fraction flow on line 310a due to the force of gravity.
• This tank 912 discharges into a pump 914 which pumps t h e third fraction along line 310b and back to the first filter device 300 for processing as was described above.
• the above described methods and apparatuses provide for an effective and efficient method for recovering fine fibers which normally are wasted as part of the paper pulp processing arts.
• a certain loss of fine fiber was accepted as part of the process of recycling paper or increasing the consistency of a fiber/water slurry.
• fiber losses must be kept to a minimum and yield must be maximized.
• the above described inventions provide methods and apparatuses which will substantially increase the fiber yield in fiber recovery processes, and yet will operate at typical processing speeds and conditions. In fact, all of the components needed to practice the inventions are available off-the-shelf which will allow for the relatively inexpensive implementation of the invention.
• any device capable of separating a slurry of fibers, contaminants and liquid carrier into fractions could be substituted.
• any type of slusher deinker, fluidized drum washer, bow screen, pressure screen, hydrocyclone, screw or belt press, dewaterer or other filter may be substituted for either the first or second filter devices as described as long as they are adapted to provide the separation described above.
• the methods and systems described above can be incorporated into larger paper processing methods or systems. In fact, it is anticipated that the above described invention will be practiced in an overall paper making environment comprising many additional steps beyond the separation of fiber from other components.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Filtration Of Liquid (AREA)
• Paper (AREA)

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• 1997
  • 1997-02-27 CA CA002247032A patent/CA2247032A1/en not_active Abandoned
  • 1997-02-27 KR KR1019980706736A patent/KR19990087327A/ko not_active Application Discontinuation
  • 1997-02-27 BR BR9707760A patent/BR9707760A/pt not_active Application Discontinuation
  • 1997-02-27 EP EP97906395A patent/EP0958430A1/de not_active Withdrawn
  • 1997-02-27 WO PCT/SE1997/000334 patent/WO1997032079A1/en not_active Application Discontinuation

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