Pulping line

Abstract

A pulping line comprising: a cooking arrangement (1) arranged to receive wood chips and to subject the wood chips to a cooking process to produce pulp; a screening arrangement (2) arranged to receive the pulp from the cooking arrangement; a waste treatment arrangement (3a-b) connected to the screening arrangement to receive waste from the screening arrangement, the waste treatment arrangement being arranged to convey at least a portion of the waste to the storage device for discarding thereof; and a washing arrangement (4) connected to the screening arrangement, the washing arrangement configured to wash at least a portion of the accepted stock received from the screening arrangement. The waste treatment arrangement, the screening arrangement, and the washing arrangement are arranged continuously within an elongated region portion of the pulping line, such as on an elongated platform. Further, a cooking arrangement is disposed at a first long side of the zone / platform.

Description

Field of the Invention

[0001] The present invention relates to the field of pulp mills for producing cellulose pulp, such as using the Kraft process. Specifically, the present invention relates to such a pulp mill having a compact layout. Background Art

[0002] Pulp mills for implementing processes such as the Kraft process and the sulfite process are well known in the art. The pulp mill includes a plurality of devices, such as reactors, towers, and washing devices, in order to be able to implement the process. The relative placement of the devices varies according to the customer's needs, but generally, these devices are arranged according to the process flow and form a pulp mill having an elongated footprint, typically having a cooking arrangement (such as a digester) at the first short end of the pulp mill and a pulp storage tower for the final product (bleached / delignified cellulose pulp) at the second (opposite) end of the pulp mill. The waste treatment device is usually placed on one side (long end) of the pulp mill to allow for convenient removal of the waste portion that cannot be recycled to the digester.

[0003] At certain locations, due to limited land space and / or high land prices, the above-mentioned type of traditional pulp mill layout is disadvantageous. Therefore, there is a need for a pulp mill with a more compact layout. Summary of the Invention

[0004] The object of the present invention is to provide a pulp mill with a more compact layout, i.e., having a smaller footprint, in particular a shorter length than traditional pulp mills.

[0005] These and other objects are achieved by the present invention by means of a pulp mill according to the independent claims.

[0006] According to a first aspect of the present invention, there is provided a pulp mill comprising: a cooking arrangement arranged to receive wood chips and subject the wood chips to a cooking process to produce pulp; a screening arrangement arranged to receive the pulp from the cooking arrangement; a waste treatment arrangement connected to the screening arrangement to receive waste from the screening arrangement, the waste treatment arrangement being arranged to convey at least a part of the waste to a storage device for its disposal; and a washing arrangement including at least one washing device connected to the screening arrangement, the at least one washing device being configured to wash at least a part of the good pulp received from the screening arrangement. The waste treatment arrangement, the screening arrangement, and the washing arrangement are continuously arranged within an elongated area portion of the pulp mill, such as arranged on an elongated platform. Furthermore, the cooking arrangement is provided at the first long side of the area / platform.

[0007] In other words, the waste treatment arrangement, the screening arrangement, and the washing arrangement are arranged continuously, i.e., arranged in sequence along a line (preferably substantially straight) within the regional portion of the pulping line, the length of which regional portion is significantly greater than the width (since these arrangements are arranged continuously). This regional portion may be defined by an elongated (raised) platform on which the waste treatment arrangement, the screening arrangement, and the washing arrangement are arranged. Such an arrangement is advantageously arranged on the platform because this allows one or more material flows to be conveyed from the platform by gravity. Further, the cooking arrangement is provided at / near the first long side of the region / platform, i.e., the cooking arrangement is arranged at one side (long end) of the region / platform, i.e., arranged at one side of one or more of the waste treatment arrangement, the screening arrangement, and the washing arrangement. This regional portion or the elongated platform may extend substantially from one short end of the pulping line to its opposite short end. The cooking arrangement may be arranged to subject the wood chips to a kraft pulping cooking process to produce pulp. The waste treatment arrangement is arranged to convey at least a portion of the waste to a storage device to allow removal of a portion of the waste, which waste will thus not be recycled to the cooking arrangement (e.g., recycled to the digester or the blow tank). Waste treatment arrangements are known in the art and may include, for example, a coarse waste treatment system (for coarse waste treatment) and / or a sludge treatment system (for treating fine waste). The coarse waste treatment system may include one or more screw presses. The sludge treatment system may include, for example, one or more flocculation tanks and / or one or more rotary screen thickeners and / or one or more screw presses.

[0008] The invention may alternatively be described as: the waste treatment arrangement, the screening arrangement, and the washing arrangement are arranged continuously along a line (which may be substantially straight) extending in a direction from one short end of the pulping line to the other. The cooking arrangement is arranged at the long end / side of the pulping line, on the side of one or more of the waste treatment arrangement, the screening arrangement, and the washing arrangement.

[0009] It should be understood that an arrangement provided at or near one side or the long end of the elongated region / platform does not necessarily mean that the arrangement is adjacent to or in direct contact with the region / platform, and embodiments may also include one or more additional devices provided between the region / platform and the arrangement. Further, it can be understood that the washing arrangement may include additional washing equipment, such as washing equipment connected to a delignification reactor and / or a bleaching tower to wash their outputs. The washing arrangement may, but does not necessarily, include all the washing equipment of the pulping line.

[0010] The inventors have realized that by overcoming the traditional view that the components of a pulping line should be arranged according to the technological process, a substantially more compact pulping line can be achieved by arranging the cooking arrangement at one (short) end and providing an output at the opposite end. Furthermore, the inventors have realized that by arranging not only the screening arrangement and the washing arrangement continuously, but also arranging the waste treatment arrangement, for example, on an elongated platform, a simplification of maintenance and a simplification of the pipe system can be achieved. This is combined with the insight that placing the cooking arrangement on one side / long end of the elongated platform will facilitate access to the short end of the platform, for example, to remove waste from the waste treatment arrangement.

[0011] In an embodiment, the pulping line further includes an overhead crane arrangement or a gantry crane arrangement displaceable along the longitudinal direction of the area or platform, the crane arrangement being configured to cooperate with the screening arrangement, the washing arrangement, and the waste treatment arrangement. Such an embodiment is advantageous because the same crane arrangement can be used for the maintenance or other operations of all three arrangements. It should be understood that an overhead crane arrangement refers to a crane arrangement including a bridging portion that includes one or more beams that travel along an elevated fixed runway / track structure extending along the longitudinal direction of the elongated area or platform, and wherein a trolley supporting, for example, a lifting mechanism is displaceable along the bridging portion in a direction substantially perpendicular to the runway / track structure. For example, such a runway / track structure can be connected to the long end wall of the building structure enclosing the elongated area or platform. A gantry crane arrangement is similar to an overhead crane arrangement, except that the bridging portion is supported by legs to form a generally U-shaped element that travels on a (non-elevated) fixed runway / track structure that extends along the longitudinal direction of the elongated area or platform, for example, at the base of the area or platform.

[0012] In an embodiment, the waste treatment arrangement is provided at the short end of the elongated area or platform such that the storage device is accessible from the short end. The storage device can include, for example, a container or other type of vessel. In an embodiment where the waste treatment arrangement is provided on an elongated (raised) platform, the storage device is arranged below the platform (entirely or at least partially below the platform) to allow easy access by a vehicle and to allow the waste to be conveyed to the storage device by gravity.

[0013] In an embodiment, the pulping line further includes one or more electrical feed arrangements connected to at least one of the cooking arrangement, the screening arrangement, the waste treatment arrangement, and the washing arrangement to supply power thereto, wherein at least one electrical feed arrangement is provided at the second long side of the platform opposite the first long side.

[0014] In an embodiment, the pulping line further includes a pulp storage device arranged to receive the washed pulp directly or indirectly from the washing arrangement, the pulp storage device being provided at the first long side of the platform. The pulp storage device can include a storage tower having a height-to-diameter ratio greater than 2.5:1.

[0015] In an embodiment, the pulping line further comprises a delignification arrangement and / or a bleaching arrangement disposed at or near the first long side. The washing arrangement may also include at least one additional washing device, each washing device being arranged to cooperate with the delignification arrangement and / or the bleaching arrangement. For example, in a sense, the additional washing device is arranged to receive the delignified or bleached pulp from a delignification or bleaching reactor. The delignification arrangement and / or the bleaching arrangement may include one or more devices (such as reactors) having a height-to-diameter ratio greater than 2.5:1.

[0016] In an embodiment, the cooking arrangement includes an impregnation tower, a digester, and a blow tank. At least one or each of the impregnation tower, the digester, and the blow tank may have a height-to-diameter ratio greater than 2.5:1.

[0017] In an embodiment, the waste treatment arrangement is also arranged to convey at least a portion of the waste to a feeding device for recycling back to the digester or the blow tank. The waste may be recycled to the digester in the form of a suspension. Such recycling and the devices (such as pumps) are well known in the art and will not be described in further detail here. The waste treatment arrangement may further include a treatment device for treating the waste before recycling. The device for treatment may include, for example, one or more shredders or one or more grinders for breaking up nodules and / or one or more waste vessels in which the waste is treated with a treatment liquid.

[0018] In an embodiment, the screening arrangement includes at least one coarse screening device and at least one fine screening device. The screening arrangement may additionally or alternatively include a combined coarse and fine screening device. Such screening devices are well known in the art and will not be described in further detail here.

[0019] In an embodiment, each component of the pulping line having a height-to-diameter ratio greater than 2.5:1 is disposed at the first long side of the platform. This may be advantageous as it simplifies the piping system and maintenance may be more convenient.

[0020] The features of the above embodiments can be combined in any practically feasible way to form embodiments having combinations of these features. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and other aspects of the present invention will now be described in more detail with reference to the drawings, which show currently preferred embodiments of the present invention, in which Figure 1 A schematic top view of an embodiment of a pulping line according to the present invention is shown. DETAILED DESCRIPTION

[0022] Figure 1 A schematic top (2D) view of an embodiment of a pulping line according to the present invention is shown.

[0023] The pulping line includes a cooking arrangement 1, which is arranged to subject wood chips to a kraft pulping process. The cooking arrangement includes an impregnation tower 1a, a pressure cooker 1b, and a discharge tank 1c. The impregnation tower 1a is arranged to receive wood chips and impregnate the wood chips with cooking liquor. The cooked finished wood chips are discharged into the discharge tank 1c. The pulping line further includes a screening arrangement 2, a waste treatment arrangement 3a-b, and a washing arrangement 4, all of which are continuously arranged on an elongated platform 5. The cooking arrangement 1 is provided at the first long side 5b of the platform.

[0024] The pulp from the discharge tank is fed to the screening arrangement 2, which includes fine screening equipment and coarse screening equipment. The waste from the screening arrangement is fed to the waste treatment arrangement 3a-b, which is arranged to convey at least a portion of the waste to a storage device in the form of containers 3c-d for its disposal. The waste treatment arrangement is provided at the short end 5a of the elongated area or platform such that the storage containers are accessible from the short end. The containers 3c-d are arranged below the platform 5. The waste treatment arrangement 3a-b is arranged to convey at least a portion of the waste to a feeding device, which can be regarded as part of the waste treatment arrangement, for recycling back to the cooking device (impregnation tower or discharge tank). The waste treatment arrangement 3a-b may include one or more of the following: (one or more) screw presses, (one or more) flocculation tanks, (one or more) rotary screening thickeners, (one or more) shredding devices, and / or (one or more) waste treatment vessels.

[0025] The washing arrangement 4 includes two washing devices 4a arranged in series, which are double roll presses connected to the screening arrangement 2 and configured to wash at least a portion of the good pulp from the screening arrangement 2 in two stages.

[0026] The washed pulp from the washing device 4a is fed into a delignification arrangement 9, which includes a first oxygen delignification reactor 9a, a second oxygen delignification reactor 9b connected to the discharge tank 9c, and a medium consistency (MC) tower 9d. The delignification arrangement cooperates with the washing device 4b (also a double roll press) of the washing arrangement 4. For example, one or both washing devices are connected between the discharge tank 9c and the medium consistency tower 9d, and the washing devices are arranged after the medium consistency tower 9d.

[0027] The delignified pulp is fed from the medium consistency tower of the delignification arrangement 9 into the bleaching arrangement 10. The bleaching arrangement includes three bleaching towers arranged in series (D0, EOP, D1 when looking from right to left). The bleaching arrangement cooperates with the washing equipment 4c (also a double-roll press) of the washing arrangement 4. The first washing equipment is connected between the D0 and EOP bleaching towers, the second washing equipment is connected between the EOP and D1 bleaching towers, and the third washing equipment is between the D1 bleaching tower and the pulp storage towers 8a, 8b. In other embodiments, the DO bleaching stage can be replaced by the Dht stage, and / or the EOP bleaching stage can be replaced by the EO or EP stage.

[0028] The delignification arrangement 9, the bleaching arrangement 10 and the pulp storage towers 8a-b are all arranged at the first long side 5b of the platform 5.

[0029] The electrical feeding arrangement 7a is connected to the screening arrangement, the waste treatment arrangement and the washing arrangement to supply them with electricity. The electrical feeding arrangement 7a is arranged at the second long side 5c of the platform, and the second long side is opposite to the first long side 5b.

[0030] The pulp line also includes a gantry crane arrangement displaceable along the longitudinal length of the platform 5, and this crane arrangement is configured to cooperate with the screening arrangement, the washing arrangement and the waste treatment arrangement. The gantry crane arrangement includes a bridging part 6b formed by one or more beams, and this bridging part is supported / lifted at its ends by legs 6c, for example forming a substantially U-shaped element, which travels on a fixed runway / track structure 6d-e extending along the two long ends 5b-c, that is, along the longitudinal length of the slender platform. A trolley 6a supporting, for example, a lifting mechanism is displaceable along the bridging part in a direction substantially perpendicular to the runway / track structure 6d-e.

[0031] Each part of the pulp line with a height-to-diameter ratio greater than 2.5:1 is arranged at the first long side 5b of the platform. The pulp line also includes solution buffer tanks 12a, 12b and filtrate tanks 11a-e. The height-to-diameter ratio of tank 12b is greater than 2.5:1, which means it is arranged at the first long side 5b, while the height-to-diameter ratios of tanks 11a-e and 12a are both less than 2.5:1, meaning they are all arranged at the second long side 5c.

[0032] The pulp line optionally includes an additional electrical feeding arrangement 7b for feeding the adjacent cooking arrangement 1, as well as a heat exchange arrangement 13 (also cooperating with the cooking arrangement).

[0033] All the above-mentioned equipment, such as impregnators, digesters, discharge tanks, double-roll presses, screening equipment, delignification reactors, bleaching towers, heat exchangers are well-known in the art and will not be described in detail here. The pipes, ducts, etc. interconnecting the above-mentioned equipment and arrangements are self-evident to those skilled in the art and are therefore not shown in the drawings.

[0034] The above description and drawings should be regarded as non-limiting examples of the present invention. Those skilled in the art will recognize that several changes and modifications can be made within the scope of the present invention. For example, the gantry crane can be replaced by an overhead crane or omitted altogether. In addition, the number and type of washing equipment, delignification reactors, bleaching towers, pulp storage towers, filtrate tanks, etc. may vary. In addition, although Figure 1 a kraft pulping line with a specific configuration is shown, other processes and kraft pulping processes different from those shown can also be considered within the scope of the claims.

Claims

1. A pulping line for producing cellulose pulp, comprising: - A cooking arrangement (1) configured to receive wood chips and subject the wood chips to a cooking process; - A screening arrangement (2) configured to receive pulp from the cooking arrangement; - A waste treatment arrangement (3a - b) connected to the screening arrangement (2) to receive waste from the screening arrangement, the waste treatment arrangement being configured to convey at least a portion of the waste to storage means (3c - d) for its disposal; - A washing arrangement (4) comprising at least one washing device (4a) connected to the screening arrangement (2), the at least one washing device being configured to wash at least a portion of the good pulp received from the screening arrangement; wherein the waste treatment arrangement (3a - b), the screening arrangement (2) and the washing arrangement (4) are arranged continuously on an elongate platform (5), and wherein the cooking arrangement (1) is provided at a first long side (5b) of the platform.

2. The pulping line according to claim 1, characterized in that, The waste treatment arrangement (3a - b) is arranged at a short end (5a) of the elongate platform (5) such that the storage means (3c - d) is accessible from the short end.

3. The pulp line according to any one of the preceding claims, characterized in that, It further comprises an electrical feeding arrangement (7a) connected to at least one of the cooking arrangement, the screening arrangement, the waste treatment arrangement and the washing arrangement (1, 2, 3a - b) to supply power thereto, the electrical feeding arrangement being arranged at a second long side (5c) of the platform, the second long side being opposite to the first long side (5b).

4. The pulping line according to any one of the preceding claims, characterized in that, It further comprises pulp storage means (8a - b) arranged to store the cellulose pulp produced at the pulping line, the pulp storage means being provided at the first long side (5b) of the platform.

5. The pulp line according to claim 4, characterized in that, It further comprises a delignification arrangement (9) and / or a bleaching arrangement (10), the delignification arrangement and / or the bleaching arrangement being arranged at the first long side (5b).

6. The pulp line according to claim 5, characterized in that, The washing arrangement (4) further comprises at least one washing device (4b, 4c) arranged to cooperate with one or more reactors of the delignification arrangement and / or the bleaching arrangement.

7. The pulping line according to any one of the preceding claims, characterized in that, It further comprises an overhead crane or gantry crane (6a - c) arrangement displaceable along the longitudinal length of the platform, the crane arrangement being configured to cooperate with the screening arrangement, the washing arrangement and the waste treatment arrangement.

8. The pulp line according to any one of the preceding claims, characterized in that, Each component of the pulping line having a height - to - diameter ratio greater than 2.5:1 is provided at the first long side (5b) of the platform.

9. The pulping line according to any one of the preceding claims, characterized in that, The cooking arrangement (1) comprises an impregnation tower (1a), a digester (1b) and a blow tank (1c).

10. The pulp line according to claim 9, characterized in that, The waste treatment arrangement (3a - b) is further arranged to convey at least a portion of the waste to a feeding device for recycling back to the digester or the blow tank.

11. The pulping line according to any one of the preceding claims, characterized in that, The screening arrangement (2) comprises at least one coarse screening device and at least one fine screening device.

12. The pulp line according to any one of the preceding claims, characterized in that, The cooking arrangement (1) is arranged to subject the wood chips to a kraft pulping cooking process.

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