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
  • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
• • 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
  • D21C1/00—Pretreatment of the finely-divided materials before digesting
• • 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
  • 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

Definitions

• the object of the present invention is a process and an installation for the continuous preparation of a paper pulp intended in particular for the paper industry or derived from a raw material consisting of lignocellulosic textile fibers, such as flax , hemp, sisal, baca, jute.
• the paper pulp intended in particular for the paper industry is produced from a lignocellulosic material and, most often, from bo s.
• the paper pulp can also be prepared from a raw material consisting of textile fibers such as, for example, flax or hemp fibers which make it possible to obtain products having excellent papermaking properties.
• the object of the invention is to propose a process and an installation for preparing a paper pulp intended in particular for the paper industry from a raw material constituted by lignocellulosic textile fibers making it possible to continuously manufacture the pulp, without load break in the preparation line of said paste and also making it possible to obtain a paste having constant physical and mechanical properties, while considerably reducing the consumption of energy, chemical reagents and water usually necessary to produce such a dough.
• the subject of the invention is therefore a process for the continuous preparation of a paper pulp intended in particular for the paper industry or derived from a dry raw material consisting of lignocellulosic textile fibers, such as flax, hemp, sisal, abaca or jute, characterized in that: the textile fibers are cut to a length of less than 5 cm, - the textile fibers are separated from foreign bodies such as agricultural residues, metallic and mineral particles ,
• - densification of the cut textile fibers is carried out, - a pre-washing and bleaching of the textile fibers is carried out continuously in a first treatment machine with two co-rotating screws to obtain a pre-bleached pulp having a dryness of between 25 and 35% and at a temperature between 75 and 95 ° C, bleaching is continued in a first latency capacity, the retention time of the pulp in said latency capacity being between 30 and ⁇ Omn, - continuous washing and bleaching of the pulp in a second treatment machine of the type with two co-rotating screws to obtain a washed and bleached pulp having a dryness of between 25 and 35%, bleaching is continued in a second latency capacity, the retention time of 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 5%,
• a draining and a pressing of the dough are carried out in order to obtain a dough having a dryness of between 30 and 35%
• the paste is diluted again in a second dilution tank to obtain a paste having a concentration of between 1.5 and 5%.
• the invention also relates to an installation for the continuous preparation of a paper pulp intended in particular for the paper industry or derived from a raw material constituted by lignocellulosic textile fibers, such as for example flax, hemp , sisal, abaca or jute, characterized in that it comprises:
• a first latency capacity to continue bleaching the dough the retention time of the dough in said first latency capacity being between 30 and 60 min,
• - a first pulp dilution tank provided with an agitator to obtain a pulp having a concentration of between 1.5 and 5%
• - pressing means for carrying out a draining and a pressing of the pulp and obtaining a pulp having a dryness of between 30 and 35%
• - Fig.l is a schematic view of an installation for the continuous preparation of a cellulose pulp, according to the invention
• - Fig. 2 is a sectional view in a vertical plane passing through the axis of a screw of the first processing machine
• FIG. 2 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 of the 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 bales of lignocellulosic textile fibers constituted for example by flax, hemp, sisal, abaca or jute and means 2 for cutting said textile fibers to a length less than 5 cm.
• the textile fibers thus cut are transported, by a pneumatic transport system comprising a fan 5, successively through means 3 for separating the textile fibers from the mineral particles, constituted for example by a cyclone, means 4 for separating the textile fibers from the particles metallic and a densifier 6 of said textile fibers making it possible to ensure a constant density and a regular and controlled flow rate of these textile fibers in order to be able to feed the first treatment machine 10 located downstream of said densifier 6.
• a pneumatic transport system comprising a fan 5
• means 3 for separating the textile fibers from the mineral particles constituted for example by a cyclone
• means 4 for separating the textile fibers from the particles metallic and a densifier 6 of said textile fibers making it possible to ensure a constant density and a regular and controlled flow rate of these textile fibers in order to be able to feed the first treatment machine 10 located downstream of said densifier 6.
• the first treatment machine 10 is of the type with two co-rotating screws and 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 form two intersecting cylindrical lobes with an inside diameter slightly greater than the outside diameter of the threads.
• 11 and 12 advantageously consist of fluted shafts, respectively 16 and 17, on which the screw sections are stacked.
• the internal bore of these screw sections is provided with grooves corresponding to those of the shaft and the external part is provided with helical threads, the pitch of which differs depending on the section considered for the treatment and transport of the material. It is thus possible to have a fairly large number of sections making it possible to vary the pitch, the depth, the number of threads and the length of each zone.
• the first processing machine 10 continuously comprises, from upstream to downstream in the direction of transport, respectively: a zone A for feeding the cut textile fibers and mixing said textile fibers with water injected at the start of this zone A,
• a second zone F for conveying and treatment with the introduction, at the start of this zone, of leaching, bleaching and dilution water reagents,
• a third zone H for conveying and processing and a zone I for transporting and discharging the dough.
• zone A of supply and mixing the sheath 15 is pierced with a supply orifice 18 surmounted by a hopper 19 connected to the outlet of the densifier 6 and to a pipe 13 for supplying recycled water.
• the screws 11 and 12 are provided with threads 20 of wide pitch and of reduced section in order to ensure the transport of the textile fibers introduced through the orifice 18 which opens widely on the two screws 11 and 12 and of distributing said textile fibers in the nets 20.
• zone B the screws 11 and 12 have threads 21 with a tight pitch and a thicker section so that the textile fibers and water are mixed and to the mixture of products is added compression of these products.
• 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 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 34 for injecting leaching reagents and dilution water and an opening 35 for injecting steam.
• the opening 34 is connected to a pipe 29 provided with a volumetric metering pump 30 for supplying the leaching reagents and dilution water.
• the leaching reagents consist of dilute caustic soda, the flow rate of which corresponds to a value between 1 and 2% of 10
• the textile fibers are mixed and mixed with the leaching reagents and at the end of this zone D, where the compression is maximum, the pectins and other products soluble in said leaching reagents are removed by means of filters 15b judiciously placed in the sheath 15. The material then passes into the second zone E of mixing and shearing.
• the zone E is provided with helical threads 25 whose winding direction is reversed with respect to that ensuring the transfer of the material in the processing machine 10.
• the threads 25 of zone E have openings 26 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 conveying and processing zone F is provided with threads 27 whose pitch and thickness have characteristics similar to those of zone D.
• the sheath 15 is provided with an injection opening leaching, bleaching and diluting water reagents.
• the opening 28 is connected to a pipe 29 which is itself connected to two pipes, respectively 29a and 29b, for the simultaneous supply of dilution water, of a caustic soda solution whose flow rate corresponds to a value between 3 and 7% of active products relative to the dry raw material and of a hydrogen peroxide solution whose flow rate corresponds to a value between 2 and 5% of active products compared to said dry raw material .
• Each line 29 and 29b is provided with a volumetric metering pump, respectively 30a and 30b. All along zone F, the textile fibers are mixed and mixed with these reagents to ensure this leaching step.
• zone G is provided with helical threads 31 the direction of winding of which is reversed with respect to that ensuring the transfer of the material into the processing machine 10 .
• openings 32 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.
• zone G At the end of zone G, the material is transported to a third zone H for conveying and processing.
• the conveying and processing zone H is provided with threads 33 whose pitch and thickness have characteristics similar to those of zones D and F.
• the textile fibers are mixed and mixed with the reagents to ensure pre-washing and bleaching.
• the processing machine of the type with two co-rotating screws is particularly well suited for carrying out these operations. Indeed, due to the rotation of the screws in the same direction, there is a reversal of the material in the interpenetration zone of the threads which is particularly effective as regards its kneading, which allows an intimate mixing of the reagents and textile fibers that have been in the upstream areas impregnated with water.
• the last zone I comprises threads whose pitch and thickness are similar to those of zone H. Pre-washing and bleaching continue during the flow of the material in zone I which, moreover, ensures the transfer to the outlet orifice 39 constituted by an opening at the downstream end of the sheath 15.
• the dough has a dryness of between 25 and 35% and its temperature is between 75 and 95 ° C. 13
• the pre-bleached pulp leaving the first treatment rachme 10 is poured into transport means 40 constituted, for example by a screw elevator, maintaining said pre-bleached pulp at a temperature corresponding to its temperature leaving the first treatment machine 10.
• This paste is thus transported in a first latency capacity 41 which has the essential role of continuing the bleaching reaction.
• the retention time of the dough in the latency capacity 41 is between 30 and 60 min.
• This second processing machine 50 shown in FIGS. 4 and 5, is in its general design similar to the first processing machine 10.
• It comprises at least two screws 51 and 52 driven in rotation about their axes by a motor and a reduction gear, not shown, inside an elongated enclosure forming a sheath 55 which envelops them.
• the screws 51 and 52 are provided with helical threads which mesh with one another and the " internal wall of the sheath 55 forms two intersecting cylindrical lobes with an inside diameter slightly greater than the outside diameter of the threads.
• the threads are nested inside each other and the two vs 51 and 52 are driven at the same speed of rotation and in the same direction so that these two screws 51 and 52 are identical, the nets being simply offset from each other.
• This second processing machine 50 comprises, continuously from upstream to downstream in the direction of transport, respectively: a zone J for feeding the bleached pulp coming from the first latency capacity 41,
• the sheath 55 is pierced with an introduction orifice 56 surmounted by a hopper 56a for feeding the dough.
• the screws 51 and 52 are provided with threads 57 with a wide pitch and a reduced section to ensure the transfer of the paste introduced by the orifice 56 which opens widely on the two screws 51 and 52 in order to distribute the material in the nets.
• the dough is immediately transported downstream of the processing machine 50 and kneaded by the effect of rotation and meshing of the screws 51 and 52. Then the dough passes into the first zone K1 of compression, shearing and dough processing.
• the first zone Kl comprises a first element of zone Kil of compression and washing and a second element of zone K12 of braking and shearing.
• the screws 51 and 52 comprise threads 58 with tight pitch and with thicker section than that of threads 57 in the area
• the sheath 55 is pierced with an opening 59 connected to a pipe 60 provided with a volumetric metering pump 61 for supplying recycled water or clear water.
• the washing effluents are discharged by means of filters 62 judiciously placed in the sleeve 55.
• the zone element K12 is provided with threads 63 the direction of winding of which is reversed with respect to that ensuring the transfer of the dough into the processing machine 50.
• threads 63 are openings 64 which extend radially from the cores of the screws 51 and 52 to the periphery of the threads and are also regularly distributed around the axis.
• the screws 51 and 52 are set so that two openings 64 periodically coincide in the central engagement zone.
• the dough passes into a second zone K2 for treatment, compression and shearing identical to the first zone Kl which comprises, on the one hand, a first element of zone compression K21 and, on the other hand , a second element of zone K22 of shear.
• the first zone element K21 is identical to the first zone element Kll which comprises threads 65 with tight pitch and the second zone element K22 is identical to the second zone element Kll and comprises threads 66 whose winding direction is reversed compared to that ensuring the transfer of the dough into the processing machine 50.
• openings 67 which extend radially from the core of each screw 51 and 52 and up to the periphery of the threads.
• the sheath 55 is connected to a pipe 68 provided with a volumetric metering pump 69 for the supply of recycled washing water or clear water. Therefore, all along the first zone element - K21, the paste is stirred and mixed with water in order to remove the residual reagents and the products resulting from the action of the reagents on the paste.
• the third zone K3 for processing, compression and shearing is identical to the first two zones, respectively Kl and K2, and comprises, on the one hand, a first element of zone K31 of compression and, on the other hand, a second element of shear zone K32.
• the screws 51 and 52 have threads 71 with tight pitch and in the second zone element K32, the screws 51 and 52 are provided with threads 72 whose winding direction is reversed with respect to that ensuring the transfer of the dough into the processing machine 50.
• openings 73 which extend radially from the core of each screw 51 and 52 to the periphery of the threads.
• the sleeve 55 is also connected to a pipe 74 provided with a volumetric metering pump 75 for supplying recycled water or clean water.
• the paste is stirred and mixed with water in order to remove the residual reagents and the products originating from these reagents on the paste.
• the washing effluents are discharged by means of filters 76 judiciously placed in the sheath 55.
• the fourth zone K4 for processing, compression and shearing comprises, on the one hand, a first element of zone K41 of compression and, on the other hand, a second element of zone K42 of shearing.
• the screws 51 and 52 comprise threads 77 with tight pitch.
• the second zone element K42 is identical to the second zone elements K12, K22 and K32 and comprises threads 78 the winding direction of which is reversed with respect to that ensuring the transfer of the dough into the processing machine 50.
• openings 79 which extend radially from the core of each screw 51 and 52 to the periphery of the threads.
• the sheath 55 is connected to a pipe 80 which is itself connected to two pipes, respectively 81 and 82 (Fig. 1), for the simultaneous supply of dilution water constituted for example with clear water, a solution of caustic soda whose flow rate corresponds to a value between 0.5 and 1.5% of active products relative to the dry raw material and a solution hydrogen peroxide whose flow rate corresponds to a value between 3 and 5% of active products relative to the dry raw material.
• dilution water constituted for example with clear water
• a solution of caustic soda whose flow rate corresponds to a value between 0.5 and 1.5% of active products relative to the dry raw material
• a solution hydrogen peroxide whose flow rate corresponds to a value between 3 and 5% of active products relative to the dry raw material.
• Each line 81 and 82 is provided with a volumetric metering pump, respectively 81a and 82a.
• the pulp is stirred and mixed with these leaching and bleaching reagents in order to ensure this essential step in the manufacture of paper pulp.
• the last zone L of the second processing machine 50 is a zone for transporting and discharging the dough through an outlet orifice 83.
• the dough On leaving the second processing machine 50, the dough has a dryness of between 25 and 35%.
• the dough is transported by appropriate means in a second latency capacity 84.
• This second latency capacity 84 has the essential role of continuing the bleaching reaction and the retention time of this paste in the second latency capacity 84 is between 60 and 120 min.
• the paste is poured into a first dilution tank 85 fitted with an agitator 86.
• This dilution tank 85 is supplied by a pipe 37 with white water or recycled water necessary for the dilution of the paste, the concentration of which at the outlet of said dilution tank 85 is between 1.5 and 5%.
• the dough thus diluted is transferred by a centrifugal pump 88 in the direction of pressing means 89 which ensures draining and pressing of the 20
• These pressing means are constituted for example by a screw press 89 or by any other suitable means.
• the effluents from the screw press 89 are recovered by a pipe 90 in a vat 91.
• the effluents thus recovered are transferred via a pipe 92 fitted with a centrifugal pump 93 to the treatment machines 10 and 40 or to a device for treating these effluents.
• the drained paste is pressed and transferred to a second dilution tank 94 provided with an agitator 95 and which is supplied with bleached water or with recycled water through a pipe 96 for diluting the paste whose concentration is included, at the outlet of said second dilution tank 94, between 1.5 and 5%. Then, the dough is discharged through a pipe 97 provided with a centrifugal pump 98 to a refining device.
• the time for continuous preparation of a paper pulp is between 1:30 and 2:30 while in traditional methods the time required for this preparation was greater than 18 hours.
• the process according to the invention requires a volume of water equal to 20m 3 per tonne of dough, while the traditional processes require the consumption of 100 to 200m 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 significantly reduce the floor space of the installation location.
• the method according to the invention also generates an energy saving of 20 to 50% and chemical reagents.

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• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Paper (AREA)

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• 1997
  • 1997-06-16 FR FR9707445A patent/FR2764614B1/fr not_active Expired - Lifetime
• 1998
  • 1998-06-09 EP EP98929527A patent/EP0991808A1/de not_active Ceased
  • 1998-06-09 CA CA002296170A patent/CA2296170A1/fr not_active Abandoned
  • 1998-06-09 WO PCT/FR1998/001178 patent/WO1998058119A1/fr not_active Ceased

Non-Patent Citations (1)

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