Device for separating light reject from the pulper vat

Abstract

Device for separating light reject from the vat (1) of the pulper comprising, on the one hand, a tank (2) of circular cross-section connected at the bottom to the vat (1), thus creating interconnected vessels, and provided with inlets (21) of dilution water in its lower part and inlets (22) of flushing water in its upper part, and at least one separator (3) of reject comprising a chamber (31) provided with a pipe (39) for accept outlet, and a semi-automatic or automatic control system (10), wherein the principle of the solution is that the separator (3) of reject is connected to the tank (2) by means of a connecting flange (102), one end of which is fixed to the casing (25) of the tank (2) and the other end of which is adapted to the detachable connection of the chamber (31) of the separator (3) of reject, wherein the casing (25) of the tank (2) comprises one or more cylindrical sections of different diameters interconnected by means of conical transitions (26), a reject discharge device (VZ) is provided in the upper part of the tank (2) outside the casing (25), the lower part of which reject discharge device (VZ) is set below the level (H) of water in the tank (2) and the upper part of which is set above the discharge hopper (43).

Description

[0001] Device for separating light reject from the pulper vat

[0002] Technicalfield;

[0003] The invention falls within the field of separation of reject in the processing of recycled paper and relates to a device for the separation of light reject from the pulper vat.

[0004] Background art:

[0005] At present, the use of a vertical top-open circular tank (trash trap) connected to the pulper vat is known in the processing of recycled paper, wherein the sedimentation of heavy reject and flotation of light reject takes place in the trash trap. This reject are extracted by a manually operated grapple or a vertical screw as described, for example, in File No. CN115533483A, or by a vertical conveyor as described in File No. US4129259A. The trash trap receives pieces of paper and loose paper fibres that are extracted with the reject and end up in landfills or incinerators. Recycled paper processors strive to achieve the least possible loss of paper fibres and the highest possible separation of reject.

[0006] One option to reduce the loss of paper fibres during recycling is to extract the water liquor with light reject from the trash trap to a device where the piece of paper are additionally pulped, the paper fibres are additionally separated from the reject and the reject is flushed with water. These devices operate in a periodic mode, are only able to process a certain amount of the total volume of reject, and therefore a greater number of these device or large-capacity devices are needed. The devices are connected to the trash trap through a pipe equipped with gate valves. The gate valves often become clogged with reject and the sliding mechanisms of the gate valve closing element become blocked. This significantly reduces the efficiency and effectiveness of the existing technology. Another option is to further process the light reject extracted from the trash trap and flush loose paper fibres and smaller pieces of paper. Larger pieces of unpulped paper go away with the reject.

[0007] The use of the previous two options simultaneously gives the best results, the disadvantages being the large number of additional devices, spatial layout requirements, energy demand and maintenance costs. However, this principle is currently the most widely used and a detailed description of the principle is given, for example, in File No. CN219951546U.

[0008] The device for the separation of floating reject from the pulper is also dealt with in File No. CZ190615, where the device consists of a pulper, an auxiliary line consisting of a disintegrator and a vibrating shaker, where there is a collection pocket on the pulper, positioned between the pulper and the disintegrator, to which the separator is connected. The disadvantage of this embodiment is that the device is designed only for separating light reject.

[0009] The reduction of paper fibre loss is also addressed in File No. JP2011038208, which deals with the overall system of the arrangement of the individual devices in the line, or Files No. US4272315A, US4726880A, EP1966435B1 and EP2274471B1, which deal with the connection of the reject separation device via a pipe directly to the pulper vat.

[0010] All current technical solutions require the use of a greater number of devices for the separation of reject, cause bigger or lesser loss of usable paper fibres and in most cases operate in a periodic mode, which is not the best for a continuous operation of the line. The periodic operating mode reduces the sorting efficiency and increases the energy demand for processing recycled paper.

[0011] The purpose of the submitted invention is to present a new design of device for the separation of light reject from the pulper vat in recycled paper processing by directly connecting the reject separator to the trash trap and eliminating the separate working chamber of the reject separator, the pipes and the gate valves, and by utilizing dilution and flushing water, to achieve increased sorting efficiency and reduced paper fibre loss, and to create a continuous separation system.

[0012]

[0013] Summary of the Invention

[0014] The stated aim is achieved by the invention in the form of a device for separating light reject from the pulper vat comprising, on the one hand, a tank of circular cross¬ section connected at the bottom to the vat, thus creating interconnected vessels, and provided with dilution water inlets in its lower part and flushing water inlets in the upper part, and at least one reject separator comprising a chamber provided with the accept outlet pipe, and a semi-automatic or automatic control system, wherein the principle of the solution is that the reject separator is connected to the tank by means of a connecting flange, one end of which is fixed to the casing of the tank and the other end of which is adapted to the detachable connection of the reject separator chamber, wherein the casing of the tank comprises one or more cylindrical sections of different diameters interconnected by means of conical transitions, and a reject discharge device is provided in the upper part of the tank outside the casing, the lower part of which reject discharge device is set below the water level in the tank and the upper part of which is set above the discharge hopper.

[0015] In the preferred embodiment, the connecting flange is rectangular or square or cylindrical in cross-section, or conical in shape, and is connected to the reject separator chamber either directly or by one or more deflectors for flow direction control, wherein the reject separator chamber features a screen and a rotor, which is driven by an electric motor.

[0016] Finally, it is preferred that the reject separator is connected to the tank or the pulper vat by one or more separate reject discharge pipes of circular or square or rectangular cross-section and that the connection of the reject separator to the tank is supplemented by the installation of a stock inlet pipe from the tank to the working chamber of the reject separator.

[0017] For devices with a specific spatial layout and for certain types of paper to be processed, it is advantageous if the reject discharge device consisting of a screw conveyor is implemented as a belt conveyor or grapple, or as an overflow with height-adjustable gates or step grates.

[0018] The presented invention achieves a new and greater effect in that the new arrangement of functional parts of the device reduces the overall spatial layout of the device, increases sorting efficiency and reduces paper fibre loss. By creating a separation system operating in continuous mode, the energy demand of the device operation is reduced, thereby reducing the cost of operation of the device. Description of Drawings

[0019] The specific examples of the invention embodiments are shown in the accompanying drawings, where

[0020] Fig. 1a) is a diagram of the basic embodiment of the device with the reject discharge device in the form of a screw conveyor from the front view,

[0021] Fig. 1b) is a diagram of the device from Fig. 1a) in the side view,

[0022] Fig. 2a) is a diagram of an alternative embodiment of the device from the front view, where the trash trap is formed by a tank consisting of two cylindrical sections connected by a conical transition,

[0023] Fig. 2b) is a diagram of the device from Fig. 2a) in the side view,

[0024] Fig. 3a) is a diagram of an alternative embodiment of the device from the front view, where the trash trap is formed by a tank consisting of two cylindrical sections connected by a conical transition,

[0025] Fig. 3b) is a diagram of the device from Fig. 3a) in the side view,

[0026] Fig. 4a) is a diagram of an alternative embodiment of the device from Fig. 1a) from the front view with the embodiment of the flow deflector of quadrangular shape, Fig. 4b) is a diagram of the device from Fig. 4a) in the side view,

[0027] Fig. 5a) is a diagram of an alternative embodiment of the device from Fig. 1a) from the front view with the embodiment of the flow deflector of conical shape, Fig. 5b) is a diagram of the device from Fig. 5a) in the side view,

[0028] Fig. 6a) is a diagram of an alternative embodiment of the device from Fig. 1a) from the front view with the reject discharge device in the form of a belt conveyor, Fig. 6b) is a diagram of the device from Fig. 6a) in the side view, Fig.7a) is a diagram of an alternative embodiment of the device from Fig. 1a) from the front view whereby the screw conveyor is replaced by a grapple and an overflow with a water permeable adjustable baffle,

[0029] Fig. 7b) is a diagram of the device from Fig. 7a) in the side view,

[0030] Fig. 8a) is a diagram of an alternative embodiment of the device from Fig. 1a) from the front view whereby the screw conveyor is replaced with an overflow with height-adjustable gates,

[0031] Fig. 8b) is a diagram of the device from Fig. 8a) in the side view,

[0032] Fig. 9a) is a diagram of an alternative embodiment of the device from Fig. 1a) from the front view whereby the reject separator is connected to the trash trap by means of a reject discharge pipe,

[0033] Fig. 9b) is a diagram of the device from Fig. 9a) in the side view,

[0034] Fig. 10a) is a diagram of an alternative embodiment of the device from Fig. 9a) from the front view, with the additional connection of the reject separator chamber to the trash trap by means of a stock inlet pipe from the pulper and separate connection of the reject separator chamber to the trash trap by means of a reject discharge pipe,

[0035] Fig. 10b) is a diagram of the device from Fig. 10a) in the side view,

[0036] Fig. 11a) is a diagram of an alternative embodiment of the device from Fig. 1a) from the front view whereby the screw conveyor is replaced with step grates, Fig. 11b) is a diagram of the device from Fig. 11a) in the side view,

[0037] Fig. 12 is a diagram of the basic embodiment of the device according to Fig.

[0038] 1a) from the front view with the control system shown,

[0039] Fig. 13 is an enlarged detail of a part of the device in the area of the connection of the reject separator to the trash trap,

[0040] Fig. 14 is a diagram of an alternative embodiment of the device with two reject separators in the side view. The drawings illustrating the presented invention and the subsequently described examples of concrete embodiments do not in any way limit the scope of protection stipulated in the definition, but merely illustrate the principle of the invention.

[0041] Detailed Description of the Invention

[0042] The device for separating light reject from the pulper vat 1 in the basic embodiment according to Fig. 1a) and Fig. 1b) comprises a cylindrical tank 2 of circular cross¬ section for concentrating reject, expertly referred to as a “trash trap”, which is connected to the pulper vat 1 at its bottom by means of a connecting channel 101, thus forming connected vessels. In the lower part of the trash trap 2, one or more inlets 21 of dilution water are disposed circumferentially in at least one row, and, in its upper part, one or more inlets 22 of flushing water are disposed in the same fashion, whereby the flow rates of the two sets of inlets 21, 22 are controlled manually or automatically. The inlets 22 of flushing water are positioned below and above the water level H in the trash trap 2 and may, in an optimum scenario, be provided with positionable spray nozzles (not shown), with the exact location of the inlets 21 of dilution water being dependent on the overall layout of the device.

[0043] In the central part, a separator 3 of reject is connected to the trash trap 2, in the chamber 31 of which a screen 32 and a rotor 33 are positioned, which rotor is driven by an electric motor 34. In its lower part, the chamber 31 is provided with a pipe 39 for the removal of the good substance, the so-called accept. The separator 3 of reject is attached to the trash trap 2 by means of a connecting flange 102, one end of which is attached, preferably welded, to the casing 25 of the trash trap 2 and the other end of which is adapted for detachable attachment, preferably bolted, of the chamber 31 of the separator 3 of reject. In the upper part of the trash trap 2, a reject discharge device 4 comprising a screw conveyor is positioned on the side. The lower part of the reject discharge device VZ implemented in the form of a screw conveyor 4 is positioned below the level H of water in the trash trap 2 and is provided with perforation 41. wherein the perforation 41 ends below or above the maximum height of the level H of water in the trash trap 2. In the upper part of the screw conveyor 4 is the drive 42 and the discharge hopper 43. Under the perforated section of the screw conveyor 4 is a pipe 5 for the discharge of overflow water, featuring flow control (not shown). In the preferred embodiment, the reject discharge device VZ may be equipped with one or more spray nozzles 44 for clean or treated water.

[0044] The described embodiment is not the only embodiment according to the invention, but as shown in Fig. 2a), Fig. 2b), Fig. 3a) and Fig. 3b), the vertical part of the trash trap 2 may feature several cylindrical sections of the casing 25 with different diameters, interconnected by a conical transition 26.

[0045] Changing the diameter of the casing 25 affects the flow rate of stock in the trash trap 2. The smaller diameter of the trash trap 2 in the lower part increases the flow velocity and reduces the deposition of wet paper at the bottom of the trash trap 2, and the larger diameter of the trash trap 2 above the separator 3 of reject increases the settling zone, while the larger diameter of the trash trap 2 near the separator 3 of reject reduces the amount of wet paper carried by the flow into the upper part of the trash trap 2.

[0046] According to Fig. 4a), Fig. 4b), Fig. 5a) and Fig. 5b), another alternative modification to the design of the device is a change of the embodiment of the connecting flange 102 for connecting the chamber 31 of the separator 3 of reject, which is rectangular or square or circular in cross-section, or conical in shape, wherein the connecting flange 102 is without a deflector 35 or with one or more deflectors 35 for directing the flow. This change in the shape of the connection of the separator 3 of reject affects the flow in the trash trap 2, whereby the deflectors 35 are straight or arc-shaped and are positioned at the connection to the cylindrical part of the trash trap 2.

[0047] According to Fig. 6a) and Fig. 6b), another alternative modification to the design of the device is a change to the design of the removal of light reject from the trash trap 2. wherein the screw conveyor 4 is replaced by a belt conveyor 6, formed by an endless conveyor belt 61, which may be made as a smooth perforated belt, or a perforated belt with chambers, or a screen belt. The reject is drained through the conveyor belt 61 and the water flows into the pipe 5 of overflow water featuring flow control. The drive 62 of the conveyor belt 6 is positioned in the upper part of the conveyor belt 61. The lower part of the conveyor belt 6 is positioned below the level H, and spray nozzles 44 for cleaning the conveyor belt 61 are positioned in the upper part of the conveyor belt 6. near the discharge hopper 63.

[0048] Furthermore, the removal of light reject from the trash trap 2 can be solved as shown in Fig. 7a) and Fig. 7b) by means of a grapple 7 which is suspended above the trash trap 2 and which continuously cleans the level H of the trash trap 2. The grapple 7 is controlled manually or automatically. In order to promote upward flow in the trash trap 2, an overflow (not shown) equipped with a water-permeable adjustable baffle 8 may be created in its upper part.

[0049] According to the illustrations in Fig. 8a) and Fig. 8b), another possible option for the removal of light reject from the trash trap 2 is the installation of a height-adjustable overflow 9 through which water and light reject flows out. The overflow 9 operates in a continuous mode, where the position of its gates is adjusted according to the level hi in the trash trap 2, or in a semi-continuous mode, where the overflow 9 is raised above the level H and once the level H has risen and once light reject has come afloat, the overflow 9 is opened at certain intervals and a certain volume of water and reject is discharged from the trash trap 2. Another possible option is the extraction of light reject by means of step grates 12. through which the water flows freely, whereby the dewatered reject is extracted into the discharge hopper 43. as shown in Fig. 11a) and Fig. 11b).

[0050] it is also possible to implement a modification of the design for connecting the separator 3 of reject to the trash trap 2 by means of the solution illustrated in Fig. 9a) and Fig. 9b), which consists of adding a separate pipe 37 for the removal of reject to carry the reject from the rotor 33 of the separator 3 of reject back to the trash trap 2 or to the vat 1 of the pulper or to a separate additional tank or device (not shown). There may be one or several pipe(s) 37 for the removal of reject and they may be circular, square or rectangular in cross-section. This solution may also be supplemented, according to Fig. 10a) and 10b) with the installation of a pipe 38 for the inlet of stock from the trash trap 2 to the working chamber 31 of the separator 3 of reject. Finally, the device may be equipped with two or more separators 3 of reject, with an example of the use of two separators 3 of reject being shown in Fig. 14.

[0051] An integral part of the device is a semi-automatic or fully automatic control system 10, an exemplary wiring of which is shown in Fig. 12. The basic supporting part of the control system 10 is a computer 11, which is interconnected with the functional, control and monitoring members of the device and which adjusts the operation of the device based on the measured flow rates, pressures, consistency, power input of electric motors and drives, and the height of the level H in the trash trap 2.

[0052] Description of device function:

[0053] During normal operation of the device, the treated stock (paper-industry substance containing light reject and heavy reject and pieces of wet unpulped paper) flows continuously from the vat 1 of the pulper to the trash trap 2.

[0054] Dilution water is supplied to the bottom of the trash trap 2 through inlets 21, which water dilutes the stock being processed to the desired consistency, maintains sufficient flow of the stock in the lower part of the trash trap 2, and prevents light reject and wet paper from depositing at the bottom of the trash trap 2, thereby reducing the loss of usable paper fibres. The flow of dilution water is regulated, as the inlets 21 of dilution water may be opened individually one or more at a time. By varying the opening and closing of the individual inlets 21 of dilution water, it is possible to reduce or completely prevent the deposition of wet paper at the bottom of the trash trap 2. The control system 10 can be used to set the automatic opening and closing of the individual inlets 21 of dilution water.

[0055] The diluted stock rises through the trash trap 2 to the separator 2 of reject. Loose paper fibres and small pieces of paper contained in the stock pass through the screen 32 of the separator 3 of reject as the good substance into the pipe 39 for accept outlet. Large pieces of paper are additionally pulped using the rotor 33 of the separator 2 of reject. The rotor 33 of the separator 3 of reject causes sufficient swirling in the trash trap 2, thus returning the reject and unpulped pieces of paper back to the trash trap 2, whereby some of the light reject and paper pieces are directed to the lower part of the trash trap 2 and some to the upper part of the trash trap 2. The reject and paper returned to the lower part of the trash trap 2 re-enter the main stream and are entrained into the separator 2 of reject.

[0056] The reject and the paper returned to the upper part of the trash trap 2 enter the area with slower flow, and the light reject is separated from the wet paper. The light reject rises to the level H and the wet paper falls back into the main flow in the area of the separator 3 of reject and is re-entrained by the separator 3 of reject As a result of re¬ entrainment of the paper by the separator 3 of reject and as a result of contact with the rotor 33 of the separator 3 of reject, the paper is pulped into pieces small enough to pass through the screen 32 of the separator 3. of reject. Light reject has greater strength and repeated contact with the rotor 33 of the separator 3 of reject separator results in minimal disintegration of this reject.

[0057] The flushing water in the upper part of the trash trap 2 is used to loosen and flush the reject and wet paper returned by the separator 3 of reject to the upper part of the trash trap 2, to direct the flow of light reject to the screw conveyor 4. which carries the light reject out of the trash trap 2, and to maintain an optimum concentration of light reject in the trash trap 2.

[0058] The flow of the flushing water is controlled. The individual inlets 22 of flushing water may be opened individually one or more at a time and directed towards the screw conveyor 4 by means of nozzles. The control system 10 can be used to set the automatic opening and closing of the individual inlets 21 of dilution water depending the oscillation of the level H in the trash trap 2.

[0059] The reject discharge device VZ, i.e. in a basic embodiment a screw conveyor 4, which is connected to the trash trap 2 from the side, is used for extracting light reject floating on the level H in the trash trap 2. The lower part of the screw conveyor 4 is positioned below the level H and the flow of water through the perforation 41 causes the reject to be devoid of water. By controlling the amount of overflow water being removed, the optimum amount of floated reject is removed from the trash trap 2. Spray nozzles 44 for clean water may be positioned in the part of the screw conveyor 4 above the level H to flush the reject being extracted, thereby rinsing out the remaining loose paper fibres.

[0060] The amount of dilution water and flushing water is set to achieve maximum sorting efficiency and is continuously adjusted according to the measured values throughout the recycled paper production process. This process can be set and corrected manually or may be controlled semi-automatically or automatically by the control system 10.

[0061] Industrial Applicability

[0062] The invention is intended for use in the paper-processing industry, namely for applications in the field of separation of reject in the processing of recycled paper, and relates to a modification of the design of a device for the separation of light reject from the pulper vat. Reference Signs List

[0063] H. Water level

[0064] VZ. Reject discharge device

[0065] 1. Pulper vat

[0066] 101. Connecting neck

[0067] 102. Connecting flange

[0068] 2. Tank (trash trap)

[0069] 21. Dilution water inlet

[0070] 22. Flushing water inlet

[0071] 25. Trash trap casing

[0072] 26. Conical casing transition

[0073] 3. Reject separator

[0074] 31. Separator chamber

[0075] 32. Screen

[0076] 33. Rotor

[0077] 34. Electric motor

[0078] 35. Deflector for flow direction control

[0079] 37. Reject discharge pipe

[0080] 38. Stock inlet pipe

[0081] 39. Accept outlet pipe

[0082] 4. Reject discharge device in the form of a screw conveyor 41. Screw conveyor perforation

[0083] 42. Screw conveyor drive

[0084] 43. Discharge hopper

[0085] 44. Spray nozzle for clean or treated water

[0086] 5. Overflow water discharge pipe

[0087] 6. Reject discharge device in the form of a belt conveyor 61. Endless conveyor belt

[0088] 62. Belt conveyor drive

[0089] 63. Discharge hopper

[0090] 7. Grapple

[0091] 8. Adjustable baffle

[0092] 9. Overflow

[0093] 10. Control system

[0094] 11. Computer

[0095] 12. Step grate

Claims

CLAIMS1. Device for separating light reject from the vat (1) of the pulper comprising, on the one hand, a tank (2) of circular cross-section connected at the bottom to the vat (1), thus creating interconnected vessels, and provided with inlets (21) of dilution water in its lower part and inlets (22) of flushing water in its upper part, and at least one separator (3) of reject comprising a chamber (31) provided with a pipe (39) for accept outlet, and a semi-automatic or automatic control system (10), characterized in that the separator (3) of reject is connected to the tank (2) by means of a connecting flange (102), one end of which is fixed to the casing (25) of the tank (2) and the other end of which is adapted to the detachable connection of the chamber (31) of the separator (3) of reject, wherein the casing (25) of the tank (2) comprises one or more cylindrical sections of different diameters interconnected by means of conical transitions (26), a reject discharge device (VZ) is provided in the upper part of the tank (2) outside the casing (25), the lower part of which reject discharge device (VZ) is set below the level (H) of water in the tank (2) and the upper part of which is set above the discharge hopper (43).

2. The device according to Claim No. 1, characterized in that the connecting flange (102) is rectangular or square or cylindrical in cross-section, or conical in shape, and is connected to the chamber (34) of the separator (3) of reject either directly or by means of one or more deflectors (35) for directing the flow.

3. The device according to Claim No. 1, characterized in that a screen (32) and a rotor (33) driven by an electric motor (34) are provided in the chamber (31) of the separator (3) of reject.

4. The device according to any one of Claims No. 1 to No. 3, characterized in that the separator (3) of reject is connected to the tank (2) or vat (1) of the pulper by one or more separate pipes (37) of circular or square or rectangular cross-section for the removal of reject.

5. The device according to Claim No. 4, characterized in that the connection of the separator (3) of reject to the tank (2) is supplemented by the installation of a pipe (38) for the inlet of stock from the tank (2) to the working chamber (31) of the separator (3) of reject.

6. The device according to any one of Claims No. 1 to No. 5, characterized in that the reject discharge device (VZ) comprises a screw conveyor (4) or a belt conveyor (6) or a grapple (7) or an overflow (9) with height-adjustable gates or step grates (12).

Images