DEVICE FOR ADDITION OF DILUTION WATER AND DISSOLUTION DRUM WITH THE SAME

Description

[0001] The present invention relates to a pulping drum with a device for adding dilution water in order to dissolve fibers contained therein or to reduce the consistency of the fiber suspension.

[0002] In pulping drums, the pulping section is separated from the screening section by a separating plate with an opening in the middle. Usually, a scoop is attached to the separating plate on the side of the pulping section. This scoop helps transport the dissolved fiber (pulp) forward to the screening section. The consistency in the pulping section can be very high (up to 30%) and therefore it is necessary to add more dilution water at the beginning of the screening section. This works quite well in conventional systems. However, it is also known that in the initial section of the screening section only relatively few fibers can pass through the screen holes of the drum due to the still high consistency. In conventional systems, the screen holes at the beginning of the screening section are therefore larger and the screening section is longer.This reduces the quality of the accept and increases investment costs and operating costs (energy consumption).

[0003] EP 1 420 108 A1 discloses a pulping drum with a rotating impeller inside, which is intended to improve the pulping of the fibers.

[0004] The object of the invention is to provide a pulping drum with a device which is arranged at the end of the pulping area of ​​the pulping drum and which ensures a continuous dilution of the pulp.

[0005] This object is achieved with a device according to patent claim 1.

[0006] The device for adding the dilution water comprises an annular groove arranged around the dissolving area of ​​the dissolving drum, with the groove bottom of the annular groove forming the outer wall of the dissolving drum. The two opposite annular groove walls protrude outward along the radial direction of the dissolving drum.

[0007] Furthermore, the device according to the invention comprises a plurality of curved tubes which project from the region of the annular groove into the interior of the drum, wherein the radially inner opening of each curved tube is oriented counter to the direction of rotation of the drum, and the radially outer opening of each curved tube is connected to the annular groove by a groove bottom hole. The dilution water from the annular groove can flow through the respective curved tubes into the pulping drum. Since the radially inner curved tubes are oriented counter to the direction of rotation of the drum, fibers cannot enter the curved tubes or the annular grooves during rotation of the pulping drum. This prevents clogging of the curved tubes and the annular groove. Even if some fibers should enter the tubes, they are flushed back into the pulping drum by the dilution water.

[0008] The invention provides continuous dilution at the end of the pulping section to reduce the consistency of the pulp suspension upon entering the screening section, while maintaining the high consistency in the pulping section. Reducing the pulp consistency allows for the use of smaller screen holes. This improves the accept quality and also enables faster removal of the pulp through the screen holes. This allows for the use of a shorter screening section with lower energy consumption and lower investment.

[0009] The curved tubes can be either arched, angled, or elbow-shaped, as long as the radially inner openings of the curved tubes are aligned against the direction of rotation of the drum. Preferably, the curved tubes on the front side, in the direction of rotation of the pulping drum, can have a shape suitable for lifting and mixing the fibers. Thus, the curved tubes can be used as additional lifting or mixing elements, which is advantageous for mixing dilution water and fibers.

[0010] The cross-sections of the curved tubes in the device according to the invention are not limited to circular shapes; they can also be oval, drop-shaped, square or rectangular, or have another polygonal shape.

[0011] Furthermore, the device according to the invention comprises a fixed annular groove cover (i.e., one that does not rotate with the dissolving drum) that covers the annular groove. A seal is arranged between the annular groove cover and the annular groove, preferably on both axial sides of the annular groove. The seal is preferably attached to the outer area of ​​the annular groove wall, but the seal can also be attached to the annular groove cover. The annular groove cover serves to cover the annular groove to prevent the dilution water from escaping from the annular groove.

[0012] The device according to the invention also has a supply line for dilution water that opens into the annular groove cover. The device can also have multiple supply lines for dilution water, and the respective supply lines are preferably arranged at the upper end of the dissolving drum. The supply lines for dilution water can extend into the annular groove.

[0013] Furthermore, the device according to the invention comprises a dilution water drain line, which opens into the annular groove cover and serves to collect the dilution water. It is advantageous if the dilution water drain line is located directly below the pulping drum. Excess dilution water can be drained through the dilution water drain line, and any fibers that have entered the annular groove can also be drained through the drain line.

[0014] The device according to the invention for adding the dilution water can also have several annular grooves.

[0015] Thus, the device according to the invention can reduce the consistency of the fiber suspension entering the screening area from 25%-30% to 5%-15%, preferably to 6%-10%. At this consistency in the screening area, the main focus is on keeping the screen holes clean, so little dilution is required in this section. This saves pumping energy.

[0016] Compared to conventional spray water pipes, pre-dilution with the device according to the invention requires a lower water pressure to achieve the same degree of dilution in the drum, which is why the required pump pressure is also reduced.

[0017] The device according to the invention may comprise a plurality of guide plates arranged in the annular groove for introducing the dilution water into the curved pipes.

[0018] The invention is described below with reference to drawings. Fig.1shows schematically a dissolving drum, wherein the device according to the invention for adding dilution water is arranged at the end of the dissolving area of ​​the dissolving drum. Fig.2 shows schematically a cross-sectional view of the end of the dissolving area of ​​the dissolving drum. Fig.3 shows a schematic detailed view of the device for adding the dilution water. Fig.4 shows schematically a perspective view of the device according to the invention. Fig.5 shows schematically a cross-sectional view of the device for adding dilution water. Fig. 6 shows schematically a partial cross-sectional view of the device for adding dilution water.

[0019] In the figures, identical or equivalent elements are provided with the same reference numerals throughout

[0020] Fig. 1schematically shows a pulping drum 200, wherein a device 100 for adding dilution water is arranged at the end of the pulping section of the pulping drum 200. The device 100 according to the invention enables continuous dilution at the end of the pulping section. Thus, the consistency of the fiber suspension entering the screening section can be reduced while the high consistency of the fibers in the pulping section is maintained. A plurality of devices 100 for adding dilution water 100 can be provided in a pulping drum 200. Here, only one device 100 for adding dilution water is shown as an example.

[0021] Fig. 2shows a schematic cross-sectional view of the end of the pulping section of the pulping drum 200. At the end of the pulping section, a device 100 for adding dilution water is provided. The dilution water enters the annular groove 110 through the dilution water supply line 140, which is arranged around the pulping section of the pulping drum 200 and rotates with the pulping drum 200. As the pulping drum 200 rotates, the dilution water enters the drum through a plurality of curved pipes 120 projecting into the drum, thereby diluting the fibers. Excess dilution water can be drained through a drain line 150 provided below. Fig. 2 shows clearly (as well as Fig. 4) that an opening 121 of the curved tube 120, located radially on the inner side, is oriented against the direction of rotation of the pulping drum 200 so that no fibers can enter the curved tubes 120. In this way, clogging of the curved tubes 120 and the annular groove 110 can advantageously be avoided. In addition, the curved tubes 120 on the front side along the direction of rotation of the pulping drum 200 have a surface shape that is suitable for lifting and mixing the fibers. In the present example, the curved tubes 120 are arched so that they can be used as special lifting elements and mixing elements. This allows the dilution water to be mixed with the fibers in the shortest possible time. In addition, the device 100 for adding the dilution water has a plurality of guide plates 114 arranged in the annular groove 110 for introducing the dilution water into the curved pipes 120.

[0022] Fig. 3shows a schematic, detailed view of the device 100. In the device 100, an annular groove 110 is arranged around the dissolving region of the dissolving drum 200, wherein the groove bottom 111 of the annular groove 110 forms the outer wall of the dissolving drum 200. The two opposite annular groove walls 112 protrude outward along the radial direction of the dissolving drum 200. The curved tubes 120 protrude from the region of the annular groove 110 into the interior of the dissolving drum 200, wherein the radially outer opening of each curved tube 120 is connected to the interior of the annular groove 110 by a groove bottom hole 113. The annular groove cover 130 is arranged in a rotationally fixed manner (does not rotate with the drum) and covers the annular groove 110.A seal (not shown in detail here) is preferably arranged between the stationary annular groove cover 130 and the rotating annular groove 110, so that the dilution water cannot escape between the annular groove walls 112 and the annular groove cover 130. Furthermore, a supply line 140 is also provided, which opens into the annular groove cover 130 in the upper region of the pulping drum 200.

[0023] Fig. 4 shows schematically a perspective view of the device 100 and Fig. 5 shows a schematic cross-sectional view thereof.

[0024] Several supply lines 140 for the dilution water may also be provided.

[0025] Fig. 6shows a schematic partial cross-sectional view of the device 100 for adding dilution water. As shown, a plurality of groove bottom holes 113 are arranged at the groove bottom 111 of the annular groove 110. The dilution water in the annular groove 110 can enter the respective curved tubes 120 through the groove bottom holes 113 and then through their openings 121 into the pulping drum 200.

[0026] The above description describes a preferred embodiment of the present invention. List of reference symbols

[0027] 100 Device for adding dilution water 200 Dissolving drum 110 Annular groove 111 Groove bottom 112 Annular groove wall 113 Groove bottom hole 114 Guide plate 120 Curved pipe 121 Radially inner opening of the curved pipe 130 Annular groove cover 140 Supply line for dilution water 150 Drain line for dilution water

Claims

1. Drum pulper (200) with a device (100) for adding dilution water, disposed at the end of a pulping range of the rotating drum pulper (200) for mixing the dilution water with pulp in the drum pulper (200), wherein the dilution water adding device (100) comprises an annular groove (110) disposed around the pulping range of the drum pulper (200), characterised in that the groove bottom (111) of the annular groove (110), forms the outer wall of the drum pulper (200) in the pulping range and two opposing annular groove walls (112) project outwards along the radial direction of the drum pulper (200); further characterised by a plurality of curved pipes (120) which project from the region of the annular groove (110) into the interior of the drum pulper (200), wherein the opening (121) of each curved pipe (120) located radially on the inner side is aligned against the direction of rotation of the drum pulper (200) and the opening of each curved pipe (120) located radially on the outer side is connected to the annular groove (110) by a groove bottom hole (113) in the groove bottom (111); an annular groove cover (130), which is arranged to be non-rotatable and covers the annular groove (110) on the outer circumference; a feed line (140) for dilution water, which opens into the annular groove cover (130); and a discharge line (150) for collecting and draining the dilution water, which opens into the annular groove cover (130).

2. Drum pulper (200) with a device (100) for adding dilution water according to claim 1, characterised in that the consistency of the pulp suspension is diluted from a high consistency of up to 30% to 5-15%.

3. Drum pulper (200) with a device (100) for adding dilution water according to claim 2, characterised in that the consistency of the pulp suspension is diluted to 6-10%.

4. Drum pulper (200) with a device (100) for adding dilution water according to one of claims 1 to 3, characterised in that the device (100) comprises a plurality of feed lines (140) for dilution water, which are arranged at the upper part of the drum pulper (200).

5. Drum pulper (200) with a device (100) for adding dilution water according to one of claims 1 to 4, characterised in that the discharge line (150) is arranged directly below the drum pulper (200).

6. Drum pulper (200) with a device (100) for adding dilution water according to one of claims 1 to 5, characterised in that a seal is provided between the annular groove cover (130) and the annular groove (110), which prevents dilution water from escaping between the annular groove cover (130) and the annular groove wall (112).

7. Drum pulper (200) with a device (100) for adding dilution water according to claim 6, characterised in that the seal is attached to the outside of the annular groove wall (112).

8. Drum pulper (200) with a device (100) for adding dilution water according to one of claims 1 to 7, characterised in that the cross-section of the curved pipes (120) are circular, oval, drop-shaped, square or rectangular.

9. Drum pulper (200) with a device (100) for adding dilution water according to one of claims 1 to 8, characterised in that the curved pipes (120) have a surface shape on the front side, viewed in the direction of rotation of the drum pulper (200), which is suitable for lifting and mixing the pulp.

10. Drum pulper (200) with a device (100) for adding dilution water according to one of claims 1 to 9, characterised in that the curved pipes (120) are arch-shaped.

11. Drum pulper (200) with a device (100) for adding dilution water according to one of claims 1 to 9, characterised in that the curved pipes (120) are angled or elbow-shaped.

12. Drum pulper (200) with a device (100) for adding dilution water according to one of claims 1 to 11, characterised in that the device (100) has a plurality of annular grooves (110).

13. Drum pulper (200) with a device (100) for adding dilution water according to one of claims 1 to 12, characterised in that the device (100) comprises a plurality of guide plates (114) arranged in the annular groove (110) for introducing the dilution water into the curved tubes (120).