Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/10—Bleaching ; Apparatus therefor
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
  • D21B1/00—Fibrous raw materials or their mechanical treatment
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
  • D21B1/00—Fibrous raw materials or their mechanical treatment
  • D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
  • D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C3/00—Pulping cellulose-containing materials
  • D21C3/22—Other features of pulping processes
  • D21C3/24—Continuous processes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials

Definitions

• the subject of the present invention is a process and an installation for the continuous preparation of a cellulose pulp intended in particular for the chemical or paper industry from a raw material constituted by textile fibers such as for example cotton linters , flax, hemp or jute.
• the method and the installation according to the present invention allow the continuous preparation of cellulose pulps to be dissolved or for chemical uses intended in particular for the manufacture of viscoses, lacquers, varnishes, sponges, nitrocelluloses.
• cellulose pulp intended in particular for the chemical or paper industry is produced from a lignocellulosic material and, more often than not from wood.
• the cellulose pulp can also be prepared from a raw material consisting of textile fibers such as, for example, cotton linters which make it possible to obtain products having excellent chemical and mechanical properties.
• the object of the invention is to propose a process and an installation for preparing a cellulose pulp intended in particular for the chemical or paper industry from a raw material constituted by textile fibers making it possible to continuously manufacture the cellulose pulp, without load break in the preparation line of said pulp and making it possible to considerably reduce the consumption of energy, chemical reagents and water usually necessary to produce such a pulp.
• the subject of the invention is therefore a process for the continuous preparation of a cellulose pulp intended in particular for the chemical or paper industry from a raw material consisting of textured fibers, characterized in that:
• the textile fibers are separated from foreign bodies such as agricultural residues, metallic and mineral particles,
• a washing and a precutting of the textile fibers is carried out continuously in a first treatment machine of the type with two co-rotating screws in order to obtain a paste having a dryness of between 25 and 40%,
• - leaching is continued in a first latency capacity, the retention time of the pulp in said first latency capacity being between 30 and 60 min, - washing and bleaching of the pulp are carried out continuously in one second treatment machine of the type with two co-rotating screws for obtaining a washed and bleached pulp having a dryness of between 25 and 40%, - bleaching is continued in a second latency capacity, the retention time d ⁇ the dough in said second latency capacity being between 60 and 120 min,
• the paste is diluted in a first dilution tank to obtain a paste having a concentration of between 1.5 and 3%,
• the invention also relates to an installation for the continuous preparation of a cellulose pulp intended in particular for the chemical or paper industry from a raw material constituted by textile fibers, characterized in that it comprises
• a first latency capacity to continue the leaching of the pulp the retention time of the pulp in said first latency capacity being between 30 and 60 minutes
• FIG. 1 is a schematic view of an installation for the continuous preparation of a cellulose pulp, in accordance with the invention
• - Fig. 2 is a perspective d ⁇ ⁇ ns intersects a vertical plane passing through the axis of a screw of the first processing machine
• - Fig. 3 is a sectional view along line 3-3 of FIG. 2
• - Fig. 4 is a sectional view in a vertical plane passing through the axis of a screw '..a second processing machine
• - Fig. 5 is a sectional view along line 5-5 of Fig. 4.
• the installation shown diagrammatically in FIG. 1 comprises in series means 1 for opening the bales and for cleaning the textile fibers constituted for example by cotton linters, flax, hemp or jute.
• the textile fibers thus purified are transported by a pneumatic transport system comprising a fan 2, successively through a condenser 3, a weighing system 4, means 5 for separation of textile fibers and metallic particles and a densifier 6 of said textile fibers so as to ensure a constant density and a regular and controlled flow of these textile fibers in order to be able to feed the first processing machine 10 located downstream of said densifier 6.
• the installation also comprises, between the means 5 for separating the textile fibers and the metallic particles and the densifier 6, a second fan 7 for transporting these textile fibers and a fan 8 for extracting the dusty air connected to a unit 9 filtration of this air.
• the first processing machine 10 comprises two screws 11 and 12 driven in rotation about their axes by a motor and a reduction gear, not shown, inside an elongated enclosure forming a sheath 15 which envelops them.
• the screws 11 and 12 are provided with helical threads which mesh with one another and the internal wall of the sheath 15 forms two intersecting cylindrical cylindrical lobes with an inside diameter slightly greater than the outside diameter of the threads.
• the screws 11 and 12 advantageously consist of splined shafts respectively 16 and 17
• the internal bore of these sections of screw is provided with grooves corresponding to those of the shaft and the external part is provided with helical threads whose pitch differs according to the section considered for the processing and transportation of the material.
• the first processing machine 10 continuously comprises, from upstream to downstream in the direction of transport, respectively: a zone A for supplying the textile fibers having a dryness of between 92 and 95% and for mixing the said textile fibers with water injected at the start of this zone A,
• zone D for conveying and treatment with the introduction, at the start of this zone, of leaching reagents and dilution water, - a second zone E of mixing and shearing,
• the sheath 15 is pierced with a supply orifice 10 surmounted by a hopper 19 connected to the outlet of the densifier 6 and a pipe 13 for supplying recovered water. or in clear water.
• the screws 11 and 12 are provided with threads 20 with a wide pitch and with a reduced cross section, in order to transport the products through this orifice 18 which opens widely on the two screws 11 and 12 and to distribute the said said products in the nets 20.
• the screws 11 and 12 comprise threads 21 with tight pitch and with a thicker section so that, when the products are mixed, they will be compressed.
• the material then passes into the first mixing and shearing zone C.
• zone C is provided with helical threads 22 whose winding direction is reversed with respect to that ensuring the transfer of the material in the processing machine 10.
• openings 23 which extend radially from the core of each screw 11 and 12 to the periphery of the threads and which are also regularly distributed around the axis.
• the screws 11 and 12 are set so that two openings 23 periodically coincide in the central meshing zone. In this way, the passage of the material flow downstream is controlled, which determines braking in this zone C, and a compression effect upstream.
• zone C As well as elsewhere, although to a lesser degree, in zone B, cause overheating. of matter, an important part of the mechanical work being converted into thermal energy.
• the material is brought to a temperature which makes it suitable for undergoing the treatment operation in the following zone.
• the conveying and processing zone D is provided with threads 24 whose pitch and thickness have characteristics similar to those of zone B.
• the sheath 15 is provided with an opening 25 connected to two pipes 26a and 26b respectively for the arrival of the leaching reagents and of the dilution water.
• the leaching reagents consist in particular of a solution of caustic soda, the flow rate of which corresponds to a value of between 2 and 5% of reactive product relative to the raw material.
• the pipes 26a and 26b are each provided with a metering pump, respectively 27a and 27b. All along zone D, the textile fibers are mixed and mixed with these reagents to ensure this leaching step.
• the treatment machine of the type with two co-rotating screws is particularly well suited for carrying out this operation.
• Zone D of conveying and processing is followed by a second zone E of mixing and shearing which is made up, like zone C, of helical threads 30 of winding opposite to that in advance of the material, or striplings and also comprising passage windows 31.
• zone E The physical and thermal phenomena, as well as the functions carried out in this zone E are similar to those carried out in zone C, that is to say a significant shearing and kneading, as well as a scrolling and a cutting of the textile fibers.
• the last zone F comprises threads 32 whose pitch and thickness are similar to those of zone D.
• the dough On leaving the first processing machine 10, the dough has a dryness of between 25 and 40%.
• the bleached pulp leaving the first treatment machine 10 is poured into means 34 of transport constituted, for example by a screw elevator, which maintain the said bleached pulp at a temperature corresponding to its outlet temperature from the first machine treatment 10.
• This paste is thus transported in a latency capacity 35 which has the essential role of continuing the leaching reaction.
• the retention time of the dough in the latency capacity 35 is between 30 and 60 min. On leaving this waiting capacity 35, the dough is poured into a second processing machine 40.
• This second treatment machine 40 (FIGS. 4 and 5) is in its general design similar to the first treatment machine 10.
• It comprises at least two screws 41 and 42 driven in rotation about their axes by a motor and a reduction gear, not shown, inside an elongated enclosure forming a sheath 45 which envelopes them.
• the screws 41 and 42 are provided with helical threads which mesh with one another and the internal wall of the sheath 45 forms two intersecting cylindrical lobes with an inside diameter slightly greater than the outside diameter of the threads.
• the threads are nested one inside the other and the two screws 41 and 42 are driven at the same speed of rotation and in the same direction so that these two screws 41 and 42 are identical, the threads being simply offset by one compared to others.
• This second processing machine 40 continuously comprises, from upstream to downstream in the direction of transport, respectively: - a zone G for feeding the bleached pulp coming from the latency capacity 35 and for mixing said pulp with injected water; at the start of this area,
• the sheath 45 is pierced with an introduction orifice 46 surmcnté of a hopper 46a for bringing products.
• the hopper 46a is connected to the output of the latency capacity 35 and to a pipe 43 for supplying recovery water or clear water.
• the screws 41 and 42 are provided with threads 47 with a wide pitch and with a reduced cross section to ensure the transfer of the products introduced by the orifice 46 which opens widely on the two screws 41 and 42 in order distribute the material in the fillets.
• the paste and this first fraction of washing water are therefore immediately transported downstream of the treatment machine 40 and mixed by the effect of rotation and engagement of the screws 41 and 42.
• the material passes into the first zone H1, of compression, shearing and processing of the dough.
• the first zone H1 comprises a first element of zone H11 of compression and washing and a second element of zone H12 of braking and shearing.
• the screws 41 and 42 comprise threads 48 with a tight pitch and a thicker section than that of the threads 47 of zone G.
• the dough is stirred and mixed with the washing water introduced into the feed hopper 46a in order to remove the residual reagents and the products coming from the action. reagents on the dough.
• the washing effluents are discharged by means of filters 53 judiciously placed in the sheath 45.
• the zone element H12 is provided with threads 49 whose winding direction is reversed compared to that ensuring the transfer of the dough into the processing machine 40.
• these openings 50 which extend radially from the core of each screw 41 and 42 to the periphery of the threads and are furthermore regularly distributed around this axis.
• the screws 41 and 42 are set so that two openings 50 periodically coincide in the central engagement zone
• the dough passes into a second zone H2 of compression, shearing and treatment identical to said first zone Hl and which comprises, on the one hand, a first element of zone H21 of compression and, on the other hand, a second element of zone H22 of shear.
• the first zone element H21 is identical to the first zone element Hll and comprises threads 48 with tight pitch and the second zone element H22 is identical to the second zone element Hll and coriport of the threads 49 whose winding direction is reversed relative to that ensuring the transfer of the dough into the processing machine 40.
• openings 50 which extend radially from the core of each screw 41 and 42 to the periphery of the threads.
• the sheath 45 is connected to a supply pipe 52 washing water.
• the paste is stirred and mixed with the dilution water in order to remove the residual reagents and the products resulting from the action of the reagents on the paste.
• the third zone H3 of compression, shearing and treatment is identical to the two first zones H1 and H2 respectively and comprises, on the one hand, a first element of zone H31 of compression and, on the other hand, a second element H32 of shear.
• the screws 41 and 42 have threads 48 with tight pitch and in the second zone element H32, the screws 41 and 42 are provided with threads 49 whose winding direction is reversed with respect to that ensuring the transfer of the material in the machine treatment 40.
• openings 50 which extend radially from the core of each screw 41 and 42 to the periphery of the threads.
• the sleeve 45 is also connected to a pipe 52 for supplying dilution water. Therefore, all along the zone element H31, the paste is stirred and mixed with the dilution water in order to remove the residual reagents and the products resulting from the action of the reagents on the paste.
• the fourth compression zone H4, of shearing and processing comprises, on the one hand, a first element of zone H41 of compression and :, on the other hand, a second element of zone H42 of shearing.
• the screws 41 and 42 comprise threads 48 with not re ⁇ iserré pitch.
• the second zone element H42 is identical to the second zone elements H12, H22 and H32 and comprises threads 49 the winding direction of which is reversed with respect to that ensuring the transfer of the dough into the processing machine 40.
• openings 50 which extend radially from the core of each screw 41 and 42 to the periphery of the threads.
• the sheath 45 is connected to a pipe 54 which is itself connected to three pipes 55a, 55b and 55c respectively (Fig. 1) for the simultaneous supply of water from dilution, of a caustic soda solution whose flow rate corresponds to a value between 0.5 and 2% of reactive product compared to the raw material and of a solution of hydrogen peroxide whose flow rate corresponds to a value between 2 and 6% of reactive product compared to the raw material.
• the pulp is stirred and mixed with these bleaching reagents in order to ensure this essential step in the manufacture of cellulose pulp.
• the treatment machine of the type with two co-rotating screws is particularly well suited for carrying out this operation.
• the last zone J of the second processing machine 40 is a zone for transporting and discharging the dough in a conveyor 60 constituted for example by a screw elevator ⁇ FIG. 1).
• the dough On leaving the second processing machine 40, the dough has a dryness of between 25 and 40%. As shown in Fig. 1, the conveyor 60 transports the dough in a second latency capacity 61.
• This second latency capacity 61 has the essential role of continuing the bleaching reaction and the retention time of this pulp in said second latency capacity 60 is between 60 and
• the paste is poured into a dilution tank 62 fitted with an agitator 63.
• This dilution tank 62 is supplied by a pipe 64 with recycled water necessary for diluting the paste, the concentration of which at the outlet of said storage tank dilution 62 is between 1 and 3%.
• the paste thus diluted is transferred by a pump 65 in the direction of a screw press 66 which ensures the drainage and the pressing of the paste to obtain a paste with a dryness of between 30 and 35%.
• the effluents from the screw press 66 are recovered by a pipe 67 in a vat 68 from which a part can be recycled in the machines of treatment 10 and 40.
• the drained and pressed paste leaving the screw press 66 is transferred to a second dilution tank 69 provided with an agitator 70 and which is supplied with recycled water through a pipe 71 for diluting the paste, the concentration is included, at the outlet of said second dilution tank 69, between 3 and 5%.
• the dough is then pumped by means of a transfer pump 72 in the direction of a so-called storage tank 73 comprising an agitator 74 intended to maintain the fibers in suspension.
• the time for continuous preparation of a cellulose pulp is between 2 and 3 hours while in traditional processes, the time required for this preparation was greater than 10 hours.
• the method according to the invention requires a volume of water equal to 30m 3 of water per tonne of dough while the traditional method requires the consumption of 100 to 150m 3 of water per tonne of dough.
• the method according to the invention allows a significant reduction in the effluents to be treated and also very significantly reduces the floor area of the installation of the installation.
• the method according to the invention also generates energy savings of 20 to 50% and chemical reagents. It makes it possible to obtain pastes having constant physical and mechanical properties.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Paper (AREA)
• Polysaccharides And Polysaccharide Derivatives (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

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ID=9484979

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Cited By (7)

Families Citing this family (7)

Citations (3)

• 1995
  • 1995-11-29 FR FR9514111A patent/FR2741638B1/fr not_active Expired - Lifetime
• 1996
  • 1996-11-18 EP EP96939136A patent/EP0864011A1/fr not_active Withdrawn
  • 1996-11-18 CN CN 96198699 patent/CN1203642A/zh active Pending
  • 1996-11-18 EA EA199800489A patent/EA000264B1/ru not_active IP Right Cessation
  • 1996-11-18 WO PCT/FR1996/001816 patent/WO1997020102A1/fr not_active Application Discontinuation

Patent Citations (3)

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