Process and device for producing a highly dehydrated fluff pulp, and fluff thus obtained

Abstract

The present invention relates to a process and a device for producing a highly dehydrated fluff pulp, which passes through two to three dewatering zones in a structure which couples a DueFormer papermaking machine to a sheet forming table. The process comprises ejecting the fibrous pulp for fluff from a headbox (2) onto a sheet forming table (11) with a horizontal lower wire (12) arranged on a discontinuous drainage shoe (13) in which a first quantity of water (100) is removed downwards through the first drainage zone (10a); and transporting the partially dehydrated fibrous pulp to the DuoFormer section (21) which forms the second drainage zone (20a), sandwiching the pulp between the lower wire and a horizontal upper wire (22) arranged under an upper discontinuous drainage shoe (23), in which a second quantity of water (200) is removed upwards, by a vacuum (50) through the upper wire (22), and downwards, by gravity, through the lower wire (12). A third discharge zone (30a) is provided, comprising a pressure roller arranged over the fluff pulp which moves along the sheet forming table (11). The final water content of the fluff pulp obtained is 6-11%.

Description

Field of the Invention

[0001] The present invention relates to a process for producing a highly dehydrated fluff pulp (PFAD).History of the invention

[0002] Cellulose fluff pulp is also known as fluffed pulp, defibrated, fibrillated, fluffy pulp, or crushed fluff pulp. It refers to a fluffed pulp made from, typically, a sheet or mat of cellulose fluff pulp. Cellulose fluff pulp, or fluff pulp, is a pulp in the form of a sheet of cellulose suitably obtained to be defibrated into cellulose fluff pulp.

[0003] Fluff pulp, or its not yet defibrated form, is a cellulose pulp that can be made from hardwood, softwood, or both, obtained from the pulping of wood. The properties of cellulose fluff can vary depending on the pulping process and the origin of the cellulose fiber. Examples of hardwood species are birch, oak, beech, maple, and eucalyptus; examples of softwood species include Hemlock cedar, fir, pine, Southern pine, Radiata pine, slash pine, Douglas fir, white fir, Scandinavian pine, and Lodgepole Alpine fir.

[0004] Traditionally, the drainage of fluff pulp to obtain a dry fluff pulp sheet is carried out on a forming table.

[0005] The machine known as a duo-former is traditionally used in paper production machines. Paper is a completely different material from fluff pulp, as it contains additives such as carbonates, starch, gums, refined cellulose, dyes, etc., often reaching 30% or more by weight of additives in the paper. Examples of commercial duo-former machines are Belbond ®< , from Valmet, or the duo-former from Voith.

[0006] Unlike paper, fluff pulp is used in its crushed form (thus forming a fluff pulp) in the manufacture of diapers and sanitary pads.

[0007] Traditionally, it is believed that using vacuum to dehydrate the upper surface of the fibrous pulp paste for fluff during cellulose fluff web formation would result in the formation of a dry, compact surface, which would prevent further water removal from the web body formed by the slurry, trapping the water inside the thick web, resulting in a heterogeneous water content along the formed fluff pulp sheet, especially for fluff pulp sheets with higher grammage or thicknesses.

[0008] Uneven drying then leads to problems such as delamination of the formed fluff pulp sheet, the formation of agglomerates after defibration of the fluff pulp sheet, a reduction in the percentage of fluff pulp defibration, a decrease in the integrity of the defibrated fibers - which is represented by a decreased rupture index in the fluff mat formed from the defibrated fibers - and a reduction in the specific absorption capacity of the mat when already formed in absorbent core constructions. These problems are exacerbated when using hardwoods in fluff pulp, which have shorter fibers.

[0009] Furthermore, a difference in roughness is noted on the surfaces of both sides of the sheet formed on the drain wire or felt, caused by the unilateral drainage typical of Fourdrinier machines. This can lead to even more uneven and complicated defibration.Brief description of the invention

[0010] One object of the present invention is a process for producing a highly dehydrated fluff pulp (PFAD), comprising: ejecting the fibrous pulp paste for fluff (PFPF) from an inlet box (2) onto a sheet forming table (11) and depositing the fibrous pulp paste for fluff (PFPF) onto a substantially horizontal lower wire (12) arranged on a substantially horizontal discontinuous drainage shoe (13) on a substantially horizontal sheet forming table (11) wherein a first quantity of water (100) is removed down from the fibrous pulp paste for fluff (PFPF) through the lower wire (12) during the passage of the fibrous pulp paste for fluff (PFPF) through the first drainage zone (10a); transporting the fibrous pulp paste for partially dehydrated fluff (LPFPD) formed on the lower wire (12) in a papermaking machine to a Duo-Former section (20) formed by a Duo-Former papermaking machine (21) and the sheet forming table (11), sandwiching the fibrous pulp paste for partially dehydrated fluff (LPFPD) between the lower wire (12) and an upper wire (22) the upper wire (22) is a substantially horizontal upper wire, arranged under a substantially horizontal discontinuous upper drainage shoe (23) the lower and upper wires (12, 22) defining therebetween a second drainage zone (20a) for additional drainage of the fibrous pulp paste for partially dehydrated fluff (LPFPD), forming a highly dehydrated fluff pulp (PFAD), the second drainage zone (20a) arranged downstream in relation to the first drainage zone (10a); wherein the fibrous pulp paste for partially dehydrated fluff (LPFPD) sandwiched between the lower and upper wires (12, 22) is transported into the second drainage zone (20a) such that, during movement of the wires (12, 22), along the second drainage zone (20a); a second quantity of water (200) is removed upwards, from the fibrous pulp paste for partially dehydrated fluff (LPFPD), through the upper wire (22) and downwards, through the lower wire (12) during the transport of the fibrous pulp paste for partially dehydrated fluff (LPFPD), along the second drainage zone (20a); the portion of water removed upwards is removed by a vacuum (50) through the upper wire (22) during movement of the wires (12, 22) along the upper shoe (23); the upper wire (22) is connected to a vacuum source (50) so that the water removed upwards is removed upwards through an upper wire (22) into an inverted box (56); collecting a portion of the water removed upwards by a vacuum opening (54) arranged in the Duo-Former paper making machine (21) on the opposite side of the upper wire (22) and the discontinuous upper drainage shoe (23); and the portion of water removed downwards is removed by gravity through the lower wire (12) during movement of the wires (12, 22) along the lower shoe (13); moving the wires (12, 22), forming and releasing highly dehydrated fluff pulp (PFAD) to obtain a highly dehydrated fluff pulp (PFAD) with a water content of 6-11%.

[0011] Another object of the present invention is a drainage system for draining fibrous pulp paste for fluff (PFPF), the system comprising: a sheet forming table (11); a Duo-Former paper making machine (21); the Duo-Former paper making machine (21) forming a second drainage zone (20a) together with sheet forming table (11); overlapping the sheet forming table (11); wherein the first drainage zone (10a) removes an initial amount of water (100) downwards, and the second drainage zone (20a), is downstream in relation to the first drainage zone (20a); the second drainage zone removes a second quantity of water (200) downwards, by gravity, and upwards, by vacuum.

[0012] Another object of the present invention is an apparatus for draining a pulp slurry for fluff (PFPF) comprising a sheet forming table (11); a Duo-Former paper making machine (21); the sheet forming table (11) comprising a first drainage zone (10a) and a second drainage zone (20a); the Duo-Former paper making machine (21) arranged on the sheet forming table (11) in the second drainage zone (20a); the Duo-Former paper making machine (21) comprising a vacuum opening (54) wherein the upward vacuum opening (54) removes water from the fibrous pulp paste for fluff (PFPF), directing the removed water upward into an inverted box (56). Figures

[0013] Figure 1 is a perspective view of the process of the present invention. Figure 2 is a view of the first drainage zone of the present invention. Figure 3 is a close-up view of the drainage zone of the present invention. Figure 4 is a close-up view of the first drainage zone of the present invention. Figure 5 is a view of the second drainage zone of the present invention. Detailed description of the invention

[0014] The present invention relates to a process for producing a highly dehydrated fluff pulp (PFAD) and a fluff pulp thus obtained.

[0015] Fluff pulp, according to the present invention, can be used in absorbent articles and hygiene products where fluff pulp is typically used in the formation of absorbent cores in infant diapers, incontinence products, and feminine sanitary pads.

[0016] The defibration of cellulose fluff pulp sheets can be carried out by hammer mills, sawmills and / or pin grinders. A traditional method is using a series of saws, or pins, or small hammers, for example, that rotate at high speed, separating the cellulose fluff pulp sheet into loose individual fibers, thus forming a fluff pulp. The fluff pulp fibers are then transported to the absorbent core forming system. Undesirable clumps or knots can form due to poor defibration of the cellulose fluff pulp sheet.

[0017] Typically, once the cellulose fluff pulp sheet has been defibrated (i.e., formed into a defibrated cellulose fluff pulp), it is fed into a forming wheel with receiving pockets that thus form an absorbent core of cellulose fluff pulp, thereby receiving a certain compression in the cellulose fluff pulp deposited there. Alternatively, a desfribated cellulose fluff mat is placed on a moving belt, for example, on a moving coarse screen, or on a moving felt, and vacuum-assisted deposited onto a lower forming screen, forming a cellulose fluff mat that can be cut and sandwiched between a non-woven fabric and a plastic or polymeric sheet liner, thus forming an absorbent diaper core for infants. In both cases, superabsorbent polymers (SAP) can be introduced into the fluff pulp during the formation of the absorbent core, prior to sandwiching. Such products can be produced by methods known in the art. For example, the absorbent core with fluff pulp can be combined with superabsorbent polymers (SAP), such as starch-acrylonitrile copolymer, hydrolyzed starch-acrylonitrile copolymer, acrylic acid (co)polymer, acrylamide (co)polymer, polyvinyl alcohol, polyacrylate / polyacrylamide copolymers, polyacrylic acid (co)polymers, sodium polyacrylate, ethylene maleic anhydride copolymer, cross-linked carboxymethylcellulose, polyvinyl alcohol copolymer, polyethylene oxide, cross-linked polyethylene oxide and starch-grafted polyacrylonitrile copolymer, salts thereof and combinations thereof.

[0018] The use of cellulose fluff pulp in sanitary products or sanitary pads necessitates that the fluff pulp be hypoallergenic, which is achieved by using little or no fillers, sizing agents, dyes or pigments, or any other compound besides the cellulose fiber.

[0019] Pulps for defibrated cellulose fluff pulp, or fluff pulps, can be produced on a papermaking machine, such as a Fourdrinier machine or any other suitable papermaking machine known in the art, and the methodologies for producing fluff pulps on various papermaking machines are well known in the art. Typically, a fibrous pulp paste for fluff (PFPF) may have a relatively low consistency of aqueous pulp fiber paste, for example, around 1% by weight, and the fibrous pulp paste for fluff (PFPF) is uniformly ejected from an outlet box onto a forming table, which features a porous forming belt, or a looping, endless forming wire, wherein the water from the fibrous pulp paste for fluff (PFPF) is gradually drained down through minute openings in the forming wire or porous belt, by gravity or optionally with the aid of vacuum, until a web-like mat of pulp fibers is formed on the forming wire or forming belt.

[0020] Typically, the still-wet fiber web (a drained fluff pulp) is transferred from the forming wire or forming belt to a wet press, which generally features a pressure roller that presses the still-wet fiber web (a drained fluff pulp) where its moisture is further reduced. The web is then subjected to a downstream drying section to remove a greater portion, or most, or even substantially all, of the moisture still retained from the forming sheet and to further consolidate the fibers into the web. After drying, the dried web, or fluff pulp, can be further rolled into a roll to form a fluff pulp roll, or it can be cut into sheets and stacked to form a fluff pulp bale.

[0021] The process for producing highly dehydrated fluff pulp (PFAD) obtained by the present invention provides fluff pulp with homogeneous dryness and also homogeneous specific volume, in contrast to the prior art which only presents the forming table.

[0022] Thus, an object of the present invention is a process for producing a highly dehydrated fluff pulp (PFAD), comprising: ejecting the fibrous pulp paste for fluff (PFPF) from an inlet box (2) onto a sheet forming table (11) and depositing the fibrous pulp paste for fluff (PFPF) onto a substantially horizontal lower wire (12) arranged on a substantially horizontal discontinuous drainage shoe (13) on a substantially horizontal sheet forming table (11) wherein a first quantity of water (100) is removed down from the fibrous pulp paste for fluff (PFPF) through the lower wire (12) during the passage of the fibrous pulp paste for fluff (PFPF) through the first drainage zone (10a); transporting the fibrous pulp paste for partially dehydrated fluff (LPFPD) formed on the lower wire (12) in a papermaking machine to a Duo-Former section (20) formed by a Duo-Former papermaking machine (21) and the sheet forming table (11), sandwiching the fibrous pulp paste for partially dehydrated fluff (LPFPD) between the lower wire (12) and an upper wire (22) the upper wire (22) is a substantially horizontal upper wire, arranged under a substantially horizontal discontinuous upper drainage shoe (23) the lower and upper wires (12, 22) defining therebetween a second drainage zone (20a) for additional drainage of the fibrous pulp paste for partially dehydrated fluff (LPFPD), forming a highly dehydrated fluff pulp (PFAD), the second drainage zone (20a) arranged downstream in relation to the first drainage zone (10a); wherein the fibrous pulp paste for partially dehydrated fluff (LPFPD) sandwiched between the lower and upper wires (12, 22) is transported into the second drainage zone (20a) such that, during movement of the wires (12, 22), along the second drainage zone (20a); a second quantity of water (200) is removed upwards, from the fibrous pulp paste for partially dehydrated fluff (LPFPD), through the upper wire (22) and downwards, through the lower wire (12) during the transport of the fibrous pulp paste for partially dehydrated fluff (LPFPD), along the second drainage zone (20a); the portion of water removed upwards is removed by a vacuum (50) through the upper wire (22) during movement of the wires (12, 22) along the upper shoe (23); the upper wire (22) is connected to a vacuum source (50) so that the water removed upwards is removed upwards through an upper wire (22) into an inverted box (56); collecting a portion of the water removed upwards by a vacuum opening (54) arranged in the Duo-Former paper making machine (21) on the opposite side of the upper wire (22) and the discontinuous upper drainage shoe (23); and the portion of water removed downwards is removed by gravity through the lower wire (12) during movement of the wires (12, 22) along the lower shoe (13); moving the wires (12, 22), forming and releasing highly dehydrated fluff pulp (PFAD) to obtain a highly dehydrated fluff pulp (PFAD) with a water content of 6-11%.

[0023] Figure 1 illustrates the coupling of the Duo-Former paper making machine (21) onto the sheet forming table (11) which can be achieved by overlapping the sheet forming table (11) onto, and aligning with, the sheet forming table (11).

[0024] The sheet forming table (11) of the process for producing highly dehydrated fluff pulp (PFAD) may also comprise a third drainage zone (30a). The third drainage zone (30a) may comprise at least one pressure roller arranged over the highly dehydrated fluff pulp (PFAD) that moves along the sheet forming table (11) and the at least one pressure roller presses the highly dehydrated fluff pulp (PFAD) and removes water from the highly dehydrated fluff pulp (PFAD) through the lower wire (12), arranged on the sheet forming table (11), thus forming a fluff pulp sheet (FPF).

[0025] The fibrous pulp paste for fluff (PFPF), from the highly dehydrated fluff pulp (PFAD) production process, can be ejected from an inlet box (2), the fibrous pulp paste for fluff (PFPF) having a consistency of 0.5-2%.

[0026] The fibrous pulp paste for fluff (PFPF), from the production process of highly dehydrated fluff pulp (PFAD), can be transported downstream at an average speed of 60 m / min.

[0027] The lower wire (12), from the process of producing a highly dehydrated fluff pulp (PFAD), can be looped in the sheet forming table (11), and the upper wire (22) can be looped in the Duo-Former paper making machine (21).

[0028] The process may also include a vacuum opening (54), which may be positioned immediately above, or in contact with, the fibrous pulp paste for partially dehydrated fluff (LPFPD) in the second drainage zone (20a). The vacuum opening (54) can provide a vacuum (50) applied over the fibrous pulp paste for partially dehydrated fluff (LPFPD), which can be 0 - 6 mCa. The process also includes an upper wire (22), which can move in the same direction and at the same speed as the lower wire (12).

[0029] A fluff pulp sheet (FPF) is provided by the process, object of the present invention, featuring 600-800 g / m 2< , with a specific volume of at least 0.6 - 0.8 g / cm 2< , a thickness of 800 - 1000 micrometers and a width of 3-4 m, with a preferred grammage of 650-750 cm 2< .

[0030] When defibrated, the fluff pulp sheet (FPF) obtained by the present invention produces a fluff pulp with a knot percentage of less than 9%, typically with a defibration energy of less than 45 kWh / t. Knots are clumps of fibers and pieces of pulp from the fluff pulp sheet that were not completely fragmented during the defibration process. Knots are defined here as the fraction of defibrated fluff pulp that is retained on an ASTM 12 mesh screen. Knot percentage is a measure of the knots retained in the mesh compared to the original amount of pulp to be defibrated. The defibration Energy is typically the amount of energy in kilojoules required to defibrate one kilogram of cellulose in dry sheet form in a process of fragmenting a dry cellulose sheet into individual fibers.

[0031] The fibrous pulp paste for partially dehydrated fluff (LPFPD) is fed from the first drainage zone (20a) to a second drainage zone (20a) in the process of producing highly dehydrated fluff pulp (PFAD), at a consistency of 1.5-3%, and highly dehydrated fluff pulp (PFAD) is fed from the second drainage zone (20a) to the third drainage zone (30a) at a consistency of 15-17%.

[0032] Fluff pulp sheet (FPF) can be made from bleached hardwood kraft pulp (BEKP).

[0033] After drying, the formed fluff pulp sheet (FPF) can either be rolled onto a roll, thus forming a cellulose fluff pulp roll, or it can be cut into sheets and stacked to form a cellulose fluff pulp bale. For example, the fluff pulp sheet (FPF) can preferably be rolled onto a roll (60).

[0034] Another object of the present invention is to provide a drainage system for draining a fibrous pulp paste for fluff (PFPF), the system comprising: a sheet forming table (11); comprising a first drainage zone (10a) and a second drainage zone (20a) a sheet forming table (11); a Duo-Former paper making machine (21); the Duo-Former paper making machine (21) forming a second drainage zone (20a) together with sheet forming table (11); overlapping the sheet forming table (11); wherein the first drainage zone (10a) removes an initial amount of water (100) downwards, and the second drainage zone (20a), is downstream in relation to the first drainage zone (20a); the second drainage zone removes a second quantity of water (200) downwards, by gravity, and upwards, by vacuum.

[0035] Another object of the present invention is an apparatus for draining a fibrous pulp paste for fluff (PFPF) comprising a sheet forming table (11); a Duo-Former paper making machine (21); the sheet forming table (11) comprising a first drainage zone (10a) and a second drainage zone (20a); the Duo-Former paper making machine (21) arranged on the sheet forming table (11) in the second drainage zone (20a); the Duo-Former paper making machine (21) comprising a vacuum opening (54) wherein the upward vacuum opening (54) removes water from the fibrous pulp paste for fluff (PFPF), directing the removed water upward into an inverted box (56).

[0036] The process, system or apparatus of the present invention provides improved drying / draining rate of fibrous pulp paste for fluff (FPS) on the sheet forming table (11). For example, the drainage process that uses only the sheet forming table (11) to achieve a dry fluff pulp sheet (FPF) with an average of 7% water, can use a sheet forming table (11) up to 25 meters long (operation of the prior art). With the process and system of the present invention, a reduction in the typical length of the sheet forming table (11) can be achieved. Alternatively, production can also be increased. For example, coupling the Duo-Former paper making machine (21) to the sheet forming table (11), with the Duo-Former (21) overlapped and aligned above the sheet forming table (11), which forms the drainage process, system and apparatus of the present invention, results not only in no negative impact on the quality of the fluff pulp but also in improved quality, even when operating with shortened tables. The prior art operation, using only the forming table (for example, an Andritz forming table) results in average production rates of 57.1 m / min. The process, system, and apparatus of the present invention resulted in average production rates of 58.3 m / min. Thus, the process, system and apparatus of the present invention allow for an increase in the drainage rate of 1.5 m / min with a direct overall impact on the production rate equivalent to 2.7% of annual production.

[0037] Furthermore, it is believed that the Duo-Former paper making machine (21), coupled to the sheet forming table (11), substantially removes the water intrinsic to the cellulose fiber. Intrinsic water is the water present inside cellulose fibers, and it is not as easily removed as extrinsic water, it can vary greatly depending on the fiber's origin. By utilizing the object of the present invention, extrinsic water is also removed, providing a shorter drainage operation or, alternatively, a fluff pulp with a lower water content or, alternatively, a higher production rate, all three factors potentially occurring simultaneously. The water content obtained using only the sheet forming table (11) in the production of a fluff pulp results in an average water content of 7.7% by weight. The process, system and apparatus of the present invention results in an average water content of 7.32% w / w, with a 5.6% reduction in water content in the fluff pulp.

[0038] The fluff pulp sheet obtained herein preferably has a density of 600-800 g / m 2< . For example, the characteristics of fluff pulp result from parameters of the fluff pulp sheet forming machine, such as consistency, screen outlet speed control, inlet box temperature, inlet box ejected flow, and other operations, such as steam application, distributed along the fluff pulp forming table and fibrous fluff pulp web; the application of drying cylinders, and other parameters such as - unlike common cellulose pulp - for example, the use of air currents for drying. These prior art operations result in a fluff pulp sheet that traditionally achieves 85-95% defibration and a rupture strength of 500-950 kPa.

[0039] A reduction in the rupture strength leads, for example and among other problems, to the breakage of the absorbent core in diapers and sanitary pads. A broken absorbent core is detrimental to the proper functioning of infant diapers, leading to leaks and requiring replacement, thus reducing the sanitary product's lifespan.

[0040] With the use of the process, system and apparatus of the present invention, the high rate of defibration is maintained, even if the forming table used is shortened, for example. For the fluff pulp sheet (FPF) obtained herein, the crushing rate typically ranges from 85-95%.

[0041] Similarly, the rupture index is also kept safe, even though the fluff pulp sheet (FPF) of the present invention is obtained with a shorter drain length. For example, the cellulose fluff pulp of the present invention has a rupture index ranging from 600-800 kPa.

[0042] Furthermore, fluff pulp sheet (FPF) does not undergo delamination or become brittle. Water removal, or drainage, is uniform throughout the body of the fibrous pulp paste for partially dehydrated fluff (LPFPD), resulting in a highly dehydrated fluff pulp (PFAD) and, consequently, a uniformly drained fluff pulp sheet (FPF) with a uniform dry water content, not only on the surface but also throughout the body.

[0043] Similarly, the present invention also provides a reduced rupture rate for the resulting fluff pulp sheet (FPF). The prior art operation, as used, results in a fluff pulp with a rupture index of 726.3 kPa, and the process, system, and apparatus of the present invention resulted in a fluff pulp sheet (FPF) with a rupture index of 705.02 kPa. The defibration of the fluff pulp sheet (FPF) is not affected, wherein the prior art operation, with only the sheet forming table (11), usually produces a fluff pulp with a defibration index of 96.7%, and the process, system and apparatus of the present invention produces a fluff pulp sheet (FPF) with a defibration index of 95.9%, with a statistically significant difference. The specific absorption capacity of the fluff pulp from the prior art operation, using only the sheet forming table, is 1.33 s / g, and with the process, system and apparatus of the present invention it is 1.32 s / g, with a maximum of 1.5 s / g. The grammage obtained is further increased from 702.2 g / m m2< to 706.6 g / m 2< , and the thickness is reduced from 944.93 mm to 937.4 mm, resulting in more compact rolls for transport.

Claims

1. Process for producing a highly dehydrated fluff pulp (PFAD), characterized in that it comprises: - ejecting the fibrous pulp paste for fluff (PFPF) from an inlet box (2) onto a sheet forming table (11) and - depositing the fibrous pulp paste for fluff (PFPF) onto a substantially horizontal lower wire (12) arranged on a substantially horizontal discontinuous drainage shoe (13) on a substantially horizontal sheet forming table (11) wherein a first quantity of water (100) is removed down from the fibrous pulp paste for fluff (PFPF) through the lower wire (12) during the passage of the fibrous pulp paste for fluff (PFPF) through the first drainage zone (10a); - transporting the fibrous pulp paste for partially dehydrated fluff (LPFPD) formed on the lower wire (12) in a papermaking machine to a Duo-Former section (20) formed by a Duo-Former papermaking machine (21) and the sheet forming table (11), sandwiching the fibrous pulp paste for partially dehydrated fluff (LPFPD) between the lower wire (12) and an upper wire (22) the upper wire (22) is a substantially horizontal upper wire, arranged under a substantially horizontal discontinuous upper drainage shoe (23) the lower and upper wires (12, 22) defining therebetween a second drainage zone (20a) for additional drainage of the fibrous pulp paste for partially dehydrated fluff (LPFPD), forming a highly dehydrated fluff pulp (PFAD), the second drainage zone (20a) arranged downstream in relation to the first drainage zone (10a); wherein the fibrous pulp paste for partially dehydrated fluff (LPFPD) sandwiched between the lower and upper wires (12, 22) is transported into the second drainage zone (20a) such that, during movement of the wires (12, 22), along the second drainage zone (20a); - a second quantity of water (200) is removed upwards, from the fibrous pulp paste for partially dehydrated fluff (LPFPD), through the upper wire (22) and downwards, through the lower wire (12) during the transport of the fibrous pulp paste for partially dehydrated fluff (LPFPD), along the second drainage zone (20a); the portion of water removed upwards is removed by a vacuum (50) through the upper wire (22) during movement of the wires (12, 22) along the upper shoe (23); the upper wire (22) is connected to a vacuum source (50) so that the water removed upwards is removed upwards through an upper wire (22) into an inverted box (56); collecting a portion of the water removed upwards by a vacuum opening (54) arranged in the Duo-Former paper making machine (21) on the opposite side of the upper wire (22) and the discontinuous upper drainage shoe (23); and the portion of water removed downwards is removed by gravity through the lower wire (12) during movement of the wires (12, 22) along the lower shoe (13); - moving the wires (12, 22), forming and releasing highly dehydrated fluff pulp (PFAD) to obtain a highly dehydrated fluff pulp (PFAD) with a water content of 6-11%.

2. Process, according to claim 1, characterized in that the sheet forming table (11) further comprises a third drainage zone (30a).

3. Process, according to claim 1, characterized in that the third drainage zone (30a) comprises at least one pressure roller arranged over the highly dehydrated fluff pulp (PFAD) that moves along a sheet-forming table (11), at least one pressure roller pressing the highly dehydrated fluff pulp (PFAD) that moves along the sheet forming table (11) and removing water from the highly dehydrated fluff pulp (PFAD) through the lower wire (12), arranged on the sheet forming table (11), forming a fluff pulp sheet (FPF).

4. Process, according to claim 1, characterized in that the fibrous pulp paste for fluff (PFPF) is ejected from an inlet box (2) with the fibrous pulp paste for fluff (PFPF) having a consistency of 0.5-2%.

5. Process, according to claim 1, characterized in that the fibrous pulp paste for fluff (PFPF) is transported downstream at an average speed of 60 m / min.

6. Process, according to claim 1, characterized in that the lower wire (12) is looped in the sheet forming table (11) and the upper wire (22) is looped in the Duo-Former paper making machine (21).

7. Process, according to claim 1, characterized in that the vacuum (50) is 2 - 6 mCa.

8. Process, according to claim 1, characterized in that the vacuum opening (54) is positioned immediately above the fibrous pulp paste for partially dehydrated fluff (LPFPD) in the second drainage zone (20a).

9. Process, according to claim 1, characterized in that the upper wire (22) moves in the same direction and at the same speed as the lower wire (12).

10. Process, according to claim 1, characterized in that the fluff pulp sheet (FPF) has a grammage of 600-800 g / m2.

11. Process, according to claim 1, characterized in that the fluff pulp sheet (FPF) comprises a specific volume of at least 0.6 - 0.8 g / cm3.

12. Process, according to claim 1, characterized in that the fluff pulp sheet (FPF) comprises a sheet with a thickness of 800-1000 micrometers.

13. Process, according to claim 1, characterized in that the fluff pulp sheet (FPF) comprises a sheet with a width of 3-4 m.

14. Process, according to claim 10, characterized in that the fluff pulp sheet (FPF) comprises a sheet with a grammage of 670 - 760 g / m2.

15. Process, according to claim 1, characterized in that the fibrous pulp paste for partially dehydrated fluff (LPFPD) is fed from the first drainage zone (20a) to the second drainage zone (20a) at a consistency of 1.5-3%.

16. Process, according to claim 1, characterized in that the highly dehydrated fluff pulp (PFAD) is fed from the second drainage zone (20a) to the third drainage zone (30a) at a consistency of 15-17%.

17. Process, according to claim 1, characterized in that the fluff pulp sheet (FPF) comprises BEKP.

18. Process, according to claim 1, characterized in that fluff pulp sheet (FPF) is rolled onto a roll (60).

19. Fluff pulp characterized in that it is obtained by the process as defined in claim 1.

20. Drainage system for draining a fibrous pulp paste for fluff (PFPF), characterized in that it comprises: a sheet forming table (11); comprising a first drainage zone (10a) and a second drainage zone (20a) a sheet forming table (11); a Duo-Former paper making machine (21); the Duo-Former paper making machine (21) forming a second drainage zone (20a) together with sheet forming table (11); overlapping the sheet forming table (11); wherein the first drainage zone (10a) removes an initial amount of water (100) downwards, and the second drainage zone (20a), is downstream in relation to the first drainage zone (20a); the second drainage zone removes a second quantity of water (200) downwards, by gravity, and upwards, by vacuum.

21. Apparatus for draining a fibrous pulp paste for fluff (PFPF) characterized in that it comprises a sheet forming table (11); a Duo-Former paper making machine (21); the sheet forming table (11) comprising a first drainage zone (10a) and a second drainage zone (20a); the Duo-Former paper making machine (21) arranged on the sheet forming table (11) in the second drainage zone (20a); the Duo-Former paper making machine (21) comprising a vacuum opening (54) wherein the upward vacuum opening (54) removes water from the fibrous pulp paste for fluff (PFPF), directing the removed water upward into an inverted box (56).

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