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
  • D21F1/80—Pulp catching, de-watering, or recovering; Re-use of pulp-water using endless screening belts
• • 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
  • D21F1/48—Suction apparatus

Definitions

• Paper making is accomplished today principally by the process and apparatus involving a Fourdrinier traveling screen or fabric, referred herein as a "wire” or “wire mesh”.
• the wire serves as a receptacle to receive a thin layer of aqueous dispersion of wood pulp and associated fibrous ma ⁇ terials, which eventually is formed into a sheet of paper on the wire after draining away the water and drying the sheet.
• Water removed from the wire early in the process is called “Whitewater” and it contains a certain amount of fibrous material that the paper manufacturer prefers to recover and to use in making paper.
• the method and apparatus of this invention is directed principally at recovering as much as possible of the valuable fibrous material from Whitewater and recycling it to the paper making process.
• this invention may be used to re ⁇ cover valuable materials from other process streams than those of a paper making procedure, e.g., dispersions of other vegetable fibers, such as cotton, animal fibers, such as wool, and synthetic fibers, such as nylon, acrylonitrile, polyester and the like.
• dispersions of non- fibrous materials can also be subjected to this invention if it is desirable to filter those materials from the liquid of the dispersion, regardless of whether the filtered materials are to be recovered or disposed of as waste.
• This invention relates to a method for removing solid fines from Whitewater containing fine pulp produced in a paper making process and recovering purified water therefrom, the method comprising:
• an aqueous dispersion of paper pulp is intro ⁇ quizzed adjacently below the upper mesh to enhance the trap ⁇ ping of the entrained solids in the Whitewater fed into the zone adjacently above the lower mesh.
• This invention also relates to an apparatus for sep ⁇ arating solid fines from water in Whitewater produced in a Fourdrinier paper making process which comprises:
• siphon means to maintain water levels wherein the web-forming zone is continuously submerged in water while water is flowing away from the zone;
• a feed tray for introducing a dispersion of pulp in water at the entrance and directed to contact the upper wire mesh and be evenly distributed across the width thereof.
• FIG. 1 is a front elevational view of one embodiment of the web-forming portion of the apparatus of this inven ⁇ tion in which a single filter web is formed;
• FIG. 2 is a side elevationsl view of the embodiment shown in FIG. 1;
• FIG. 3 is a side elevational view of a second embodi ⁇ ment of the web-forming portion of the apparatus of this invention in which a double filter web is formed;
• FIG. 4 is a schematic front elevational view of the entire assembly of the apparatus of this invention employing the apparatus of FIGS. 1 and 2;
• FIG. 5 is a cross section taken at 5—5 of FIG. 4;
• FIG. 6 is a schematic front elevational view of the entire assembly of the apparatus of this invention employing the apparatus of FIG. 3.
• FIGS. 1-3 there is shown the web forming portion of Fourdrinier type apparatus and process of this invention which functions generally as described and claimed in co- pending U.S. Patent No. 4,895,623, dated January 23, 1990.
• An upper wire mesh 12 is guided around cylinder 25 to pass under a water removal device 10 which operates as a siphon.
• a lower wire mesh 11 is guided around cyl ⁇ inder 26 to travel closely adjacent to wire mesh 12 in a substantially parallel movement with both meshes traveling at the same speed.
• Lower wire mesh 11 and upper wire mesh 12 actually converge upon each other to define a wedge- shaped space or zone between the two as they travel past water removal device 10.
• Lower wire mesh 11 is supported on a solid plate 13 which is a fluid flow barrier.
• Water is removed by a siphon means in a water removal container 10 having a water level 29.
• Whitewater 27 having fines, etc.. therein is fed from source 28 to the upper surface of lower wire mesh 11.
• an aqueous dis ⁇ persion of paper pulp is fed in contrast to Whitewater which is the water left after passing through a Fourdrinier type apparatus.
• the Whitewater passes under water removal con ⁇ tainer 10 the water in stock 73 is siphoned away by a system whereby the water level in container 10 is at 29 and is con ⁇ trolled through a float system 24 to drain water continuously away through valved exits 21 and 22.
• the stock 73 on wire mesh 11 is submerged in water so that no air-water meniscus is present at or near wire mesh 11.
• FIG. 2 there is a more detailed showing of the siphon means and the water level controls wherein water from stock 73 flows upward through manifold 15 to a drainage tank 16.
• FIG. 3 there is shown a similar system to that in FIGS. 1 and 2 except that a siphon means is applied both above and below stock 73 simultaneously.
• a similar con ⁇ tainer to water removal container 10 . is placed in contact with lower wire mesh 11 instead and plate 13 is removed.
• FIGS. 4 and 5 there is shown the present invention using the water removal siphon system of FIGS. 1 and 2 and in FIG. 6 there is shown the siphon system of the double sided siphon system of FIG. 3.
• upper wire mesh 12 and lower wire mesh 11 supported on plate 13 approach each other at an angle so as to form a wedge-shaped space 64.
• Whitewater through pipe 59 from supply line 62.
• an aqueous dispersion of paper pulp through pipe 67 as a branch from supply line 66.
• This dis ⁇ persion may be the same as that used as feed stock 28 from feed box of U.S. Patent No. 4,895,623 or it may be merely paper pulp in water without the surface active agents, dis- persants, bleach and other additives found in the usual paper pulp stock.
• Pipe 67 terminates so that the outflowing dispersion contacts upper wire mesh 12 where it approaches the leading edge of water removal container 10. Accordingly, the pulp in the dispersion from pipe 67 is sucked against wire mesh 12 and forms a filter web as wire mesh 12 moves across the siphon mouth 14 of container 10. Water cannot flow downwards from wedge-shaped space 64 because of the presence of fluid flow barrier plate 13 supporting lower wire mesh 11.
• Whitewater from pipe 59 is sucked through filter web 71 causing any solids (usually fines of fiber and similar materials) to be caught by the filter web 71 and the fil ⁇ tered water passes through valved outlets 21 to a pool 56 which is conducted out exit 57 in the direction of arrow 58 for use elsewhere, e.g., in sprays 45 and 51 or other places in the paper plant.
• FIG. 5 there is shown a cross section of pipe 59 to show how the Whitewater is directed to be evenly distributed across the entire width of wire meshes 11 and 12 and to break up any large clumps or to restrain extraneous matter from entering between the wire meshes.
• FIG. 6 the same process and apparatus as in FIG. 4 is employed except that fluid barrier 13 is removed and in its place there is put a lower siphon means with a mouth with deflectors and a water removal container (similar to 10 but not shown for the sake of simplicity) .
• Whitewater is fed from pipe 59 into the center of the wedge-shaped space 64 while a pulp dispersion from supply line 66 is fed through pipe 67 to contact upper wire mesh 12 and also through pipe 167 to contact lower wire mesh 11.
• a filter web 71 is formed on upper wire mesh 12 and a similar filter web 171 is formed on lower wire mesh 11 with white- water fed in between.
• the siphon system pulls water through both filter webs 71 and 171 to be collected in pool 56 and recycled through exit 57 to the paper making process.
• the two filter webs 71 and 171 continue in contact with their respective wire meshes 12 and 11 until both are washed off by sprays 45 and 51 into pool 49 of concentrated pulp which is recycled through exit 47 to the paper making process.
• Suction box 53 (see FIG. 4) is eliminated in this arrange ⁇ ment because it is not normally needed, although a suction box may, if desired, be included on the lower wire mesh downstream from container 10.
• the system of this inven ⁇ tion can be used to filter other media than Whitewater. Any dispersion of solids in a liquid (particularly in water) can be treated by the present invention to separate the solids and purify the water and recover or recycle each.

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• 1990
  • 1990-11-02 WO PCT/US1990/006496 patent/WO1991006704A1/en not_active Application Discontinuation
  • 1990-11-02 JP JP50052691A patent/JPH04505190A/ja active Pending
  • 1990-11-02 CA CA 2045515 patent/CA2045515A1/en not_active Abandoned
  • 1990-11-02 BR BR909006989A patent/BR9006989A/pt not_active Application Discontinuation
  • 1990-11-02 EP EP19900917507 patent/EP0455784A4/en not_active Withdrawn

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