Sealing device

Abstract

A sealing device 100 for a shaft, comprising at least a first seal element 10a arranged around a shaft 30 and at least a second seal element 10b arranged around the shaft 30, wherein the first seal element 10a and the second seal element 10b comprise adjustable seal elements, the first seal element 10a and the second seal element 10b respectively comprising an outer shell 14a, 14b of an elastic material and a hollow core 12a, 12b, wherein the hollow core 12a, 12b of the first seal element 10a and / or the second seal element 10b is pressurized with a fluid for an adjustable sealing effect.

Description

[Technical field]

[0001] The present invention relates to a sealing arrangement. In particular, but not exclusively, the present invention relates to a sealing arrangement for sealing an axle or shaft. In particular, but not exclusively, the present invention relates to a sealing arrangement for sealing an axle or shaft of a white liquor or lime filter. [Background technology]

[0002] Environments with alkaline liquids or liquid suspensions containing solid residues, such as particles, place high demands on any sealing device, both for technical and safety reasons. Traditionally, braided sealing ropes are used.

[0003] In such environments, the seals must provide an effective seal since any alkaline liquid, such as white liquor, will easily penetrate traditional seals as compared to, for example, water. Additionally, suspensions containing solid residues can harden the seals and begin to wear away both the seals and the sealing surfaces.

[0004] Furthermore, sealing the axles or shafts of e.g. rotary filters in white liquor plants, which generally rotate, reciprocate axially and are exposed to fluctuating pressures and temperatures depending on the process conditions, requires seals that are able to adapt to the conditions and conform to the sealing surface for effective sealing in all circumstances. Previously, braided seals with elastic cores were used in addition to sealing ropes.

[0005] The inventors have discovered that existing solutions do not provide efficient sealing in all circumstances. Thus, a sealing device having an adjustable sealing element for efficient sealing is provided that uses a pressurized sealing element whose pressure is monitored and adjusted. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to improve upon existing solutions by providing an efficient sealing arrangement that uses an adjustable sealing element. [Means for solving the problem]

[0007] Various aspects of the illustrative invention are set forth in the following claims.

[0008] According to a first exemplary aspect of the present invention, there is provided a sealing device for a shaft, comprising: at least a first seal element disposed about the shaft; at least a second sealing element disposed about the shaft; Equipped with the first seal element and the second seal element comprise adjustable seal elements; the first seal element and the second seal element each include an outer shell of a resilient material and a hollow core; The hollow core of the first sealing element and / or the second sealing element is pressurized with a fluid for an adjustable sealing effect. A sealing arrangement for the shaft is provided.

[0009] The shell may include an outer layer of braided material.

[0010] At least the first seal element and / or the second seal element may include electrical circuitry configured to become disconnected when the outer shell wears or tears.

[0011] The sealing device may further include valves connected to the inlets for supplying fluid to pressurize the first and second sealing elements, respectively.

[0012] The fluid may include a gas, such as air.

[0013] The sealing device may further comprise a fluid space between at least the first seal element and the second seal element.

[0014] The pressure in the fluid space may be adjustable.

[0015] The shaft may include a shaft of a rotary filter unit.

[0016] According to a second exemplary embodiment of the present invention, establishing a first pressure within a first seal element disposed about the shaft; establishing a second pressure within a second seal element disposed about the shaft; monitoring a pressure within the first sealing element and / or the second sealing element; Adjusting the pressure inside the first sealing element and / or the second sealing element for an adjustable sealing effect; There is provided a method for controlling a sealing device for a shaft according to a first exemplary embodiment of the present invention, comprising:

[0017] The method may further include monitoring wear of the first seal element and / or the second seal element using electrical circuitry.

[0018] The method may further include scheduling replacement of the first seal element or the second seal element based on monitoring the pressure and / or monitoring the wear.

[0019] According to a third exemplary aspect of the present invention, there is provided a rotary filter unit comprising the sealing device of the first exemplary aspect of the present invention.

[0020] According to a fourth exemplary aspect of the present invention, there is provided a control system for controlling the sealing arrangement of the first exemplary aspect of the present invention, comprising a control device connected to at least one measurement and actuator module for performing the method of the second exemplary aspect of the present invention.

[0021] According to a fifth exemplary aspect of the present invention there is provided a computer program comprising computer executable program code which, when executed by a processor, causes the processor to perform the method according to the second exemplary aspect.

[0022] According to a sixth exemplary aspect of the present invention, there is provided a non-transitory memory medium comprising the computer program of the fifth exemplary aspect.

[0023] Different non-binding exemplary aspects and examples of the present invention have been presented above. The above examples are merely used to illustrate selected aspects or steps that may be utilized in the implementation of the present invention. Some examples may be presented only with respect to some exemplary aspects of the present invention. It should be appreciated that the corresponding examples may also be applied to other exemplary aspects.

[0024] For a more complete understanding of the exemplary embodiments of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0025] [Figure 1] FIG. 2 shows a schematic cross-sectional view of a sealing device according to an exemplary embodiment of the present invention. [Diagram 2] 4 shows a further schematic cross-sectional view of a sealing device according to an exemplary embodiment of the present invention; [Diagram 3] FIG. 2 shows a schematic three-dimensional view of a sealing device according to an exemplary embodiment of the present invention. [Figure 4] FIG. 2 shows a schematic cross-sectional view of a sealing element according to an exemplary embodiment of the present invention. [Diagram 5] FIG. 2 shows a schematic block diagram of a sealing device control system in accordance with an exemplary embodiment of the present invention. [Figure 6] FIG. 2 is a flow chart of a sealing device control method according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] FIG. 1 shows a schematic cross-sectional view of a sealing device 100 according to an exemplary embodiment of the invention. The sealing device 100 is shown around the shaft 30 of a disc filter unit at its end. In one embodiment, the filter unit is a rotary filter unit of a white liquor plant, such as a white liquor filter or a lime mud filter. The sealing device 100 comprises at least a first or outer sealing element 10a and at least a second or inner sealing element 10b. The first sealing element 10a and the second sealing element 10b are arranged concentrically around the shaft 30. In one embodiment, the device comprises at least one further sealing element (not shown). The device 100 comprises a fluid space 60 between the first sealing element 10a and the second sealing element 10b. The fluid space 60 is filled with a fluid, in one embodiment water, to enhance the sealing effect and to flush the sealing surfaces while preventing solid particles from wearing away the sealing elements. In one embodiment, the pressure of the fluid in fluid space 60 is controlled or regulated to a suitable pressure, such as by regulating the flow of fluid into fluid space 60. In one embodiment, the fluid pressure in fluid space 60 is greater than the pressure inside the rotary filter.

[0027] The shaft 30 rotates about its axis, as indicated by the arrow in FIG. 1. The direction of rotation is not critical. Furthermore, the shaft 30 reciprocates axially, as indicated by the arrow in FIG. 1. The combined rotation and reciprocation places high demands on the sealing device 100. Using conventional seals, the sealing elements would have to apply high pressing forces which would cause high friction. Furthermore, it is costly and difficult to manufacture a perfectly circular shaft, especially for hollow shafts, as is the case in one embodiment used in rotary filter units, so if the shaft 30 is not perfectly circular, the seal may be compromised. Furthermore, it is noted that the interior of the filter unit is pressurized and contains alkaline substances which make the operating environment harsh.

[0028] Thus, the first sealing element 10a and the second sealing element 10b are adjustable, i.e. the sealing effect is controlled by pressurizing the sealing elements 10a, 10b with a pressurized fluid, in one embodiment a gas such as air, through the pressure valves 16a, 16b. The internal pressure of the first sealing element 10a and the second sealing element 10b is individually adjustable, i.e. the pressurization does not have to be at the same level for both. In one embodiment, the internal pressure of the first pressure element 10a and / or the second pressure element 10b is set to correspond to the ambient pressure. The adjustable pressure contributes to an adjustable sealing effect, i.e. the pressure of the first sealing element 10a and the second sealing element 10b is adjusted in such a way as to provide a sealing effect in each operating situation. The pressure in the fluid space 60 is adjusted in one embodiment relative to the pressure of the first sealing element 10a and the second sealing element 10b. In one embodiment, the pressure in the fluid space 60 is lower than the pressure of the first sealing element 10a and the second sealing element 10b. In one embodiment, the fluid to the fluid space 60 is supplied via a hydraulic accumulator to ensure the sealing effect of the fluid in case of a fluid supply interruption. FIG. 1 further shows the arrangement of the first sealing element 10a and the second sealing element 10b. The first sealing element 10a is arranged in one embodiment between the outer shell 20 of the filter unit and the gland 40. The second sealing element 10b is arranged in one embodiment between the gland 40 and the interior of the filter unit. Although the first sealing element 10a and the second sealing element 10b are shown to have the same size, i.e., diameter and inner cross-sectional diameter, in further embodiments the first sealing element 10a and the second sealing element 10b have different sizes. In one exemplary embodiment, the diameter of the first sealing element 10a and the diameter of the second sealing element 10b, i.e., the diameter of the shaft, is 1300 mm.

[0029] Fig. 2 further illustrates a schematic cross-sectional view of a sealing device according to an exemplary embodiment of the present invention, enlarged with respect to Fig. 1. Fig. 2 illustrates a first sealing element 10a and a second sealing element 10b. In one exemplary embodiment, the sealing elements comprise ExSeal sealing elements. Each sealing element 10, 10b comprises an outer shell 14a, 14b and a hollow core 12a, 12b. In one embodiment, the outer shell 14a, 14b comprises an elastic material. In one embodiment, the outer shell 14a, 14b comprises a layer of elastic material, such as rubber, and an outer layer that is resistant to wear and tear, for example an outer layer of a braided material.

[0030] The hollow cores 12a, 12b of the first and second sealing elements 10a, 10b are pressurized with a fluid, in one exemplary embodiment a gas such as air. The fluid is introduced into the interior of the first and second sealing elements 10a, 10b through nipples or valves 18a, 18b, respectively. The valves 18a, 18b are connected through the outer shell of the filter unit to inlets 16a, 16b, respectively, for supplying the fluid to pressurize the sealing elements 10a, 10b.

[0031] In one embodiment, as shown in Figures 1 and 2, the valves 18a, 18b and inlets 16a, 16b are arranged in a direction perpendicular to the axis of the shaft about which the seal element is disposed. In a further embodiment, shown in Figure 3, the valves 18a, 18b and inlets 16a, 16b are arranged in a direction parallel to the axis of the shaft about which the seal element is disposed. In yet a further embodiment, the arrangement of the valves 18a, 18b and inlets 16a, 16b is different for the first seal element 10a and the second seal element 10b.

[0032] FIG. 3 shows a schematic three-dimensional view of a sealing device according to an exemplary embodiment of the present invention. FIG. 3 shows a first sealing element 10a and a second sealing element 10b around a shaft 30. FIG. 3 also shows the seams 15a, 15b of the first sealing element 10a and the second sealing element 10b. The sealing elements 10a and 10b are in one embodiment not formed into a continuous ring, but from a tube closed at both ends thereof and attached at their ends at the seams 15a, 15b. FIG. 3 further shows the inlets 16a, 16b of the first sealing element 10a and the second sealing element 10b, respectively. In the embodiment of FIG. 3, the tube of the inlet 16b of the second sealing element 10b is arranged in the seam 15a of the first sealing element 10a.

[0033] FIG. 4 shows a schematic cross-sectional view of a sealing element according to an exemplary embodiment of the present invention. FIG. 4 shows a first sealing element 10a by way of example, and those skilled in the art will appreciate that the structure and function of the second sealing element 10b and further sealing elements are similar in one embodiment. The first sealing element comprises a hollow core 12a, an elastic shell 14a, and a valve 18a attached to an inlet 16a for supplying pressurized fluid, as previously described with respect to FIGS. 1-3. In the embodiment of FIG. 4, the sealing element 10a further comprises at least one electrical circuit element 50a configured to conduct electrical current until it is broken. The electrical circuit element 50a comprises, for example, a copper wire in one embodiment. The electrical circuit element 50a is disposed in the outer shell 14a of the sealing element 10 in such a way that when the sealing element 10a is subject to wear, the outer shell wears or tears during use, causing the electrical circuit element 50a to break at some point. If the electrical circuit element 50a becomes disconnected, it will no longer conduct a current that can be detected, thus detecting excessive wear of the sealing element 10a. In a further embodiment, the sealing element 10a further comprises a temperature sensor embedded therein.

[0034] Fig. 5 shows a schematic block diagram of a sealing device control system according to an exemplary embodiment of the present invention. Fig. 5 shows a sealing device 100 and a control means connected thereto. The control system comprises a control device 500. In one embodiment, the control device 500 is a stand-alone control device, such as a local control device or a cloud-based control system, configured to control the sealing device 100. In a further embodiment, the control device 500 is integrated into a mill-wide control system.

[0035] The control device 500 is connected to the measurement and actuator modules 510a, 510b. In one embodiment, a separate measurement and actuator module is provided for each sealing element 10a, 10b. In a further embodiment, a single measurement and actuator module is provided jointly for all sealing elements 10, 10b. The measurement and actuator modules 510a, 510b are configured to measure the pressure inside the first sealing element 10a and the second sealing element 10b of the sealing device 100. Furthermore, the measurement and actuator modules 510a, 510b are configured to operate means for supplying and regulating the pressure inside the first sealing element 10a and the second sealing element 10b, such as valves. In a further embodiment, the measurement and actuator modules 510a, 510b are configured to monitor the current conducted by the electric circuit element 50a in order to detect wear that has caused an open circuit in the electric circuit. In yet a further embodiment, the measurement and actuator modules 510a, 510b are configured to monitor the temperature of the sealing elements 10a, 10b.

[0036] FIG. 6 shows a flow chart of a sealing device control method according to an exemplary embodiment of the present invention. In an embodiment, the method according to an exemplary embodiment of the present invention is executed by a processor, for example a processor of a control system or control device 500. In step 610, the pressure inside at least the first sealing element 10a and / or the second sealing element 10b and the pressure in the fluid space 60 are set. In an embodiment, the pressure is set to a pre-determined pressure value. In a further embodiment, the pressure is set depending on the operating pressure of the filter unit in the current operating situation. In an embodiment, the pressure is set to different values ​​for the first sealing element 10a and the second sealing element 10b. In an embodiment, the pressure inside at least the first sealing element 10a and the second sealing element 10b is substantially within the range of 0.5-4 bar, preferably 1.6-3 bar.

[0037] In step 620, the pressure inside the first sealing element 10a and / or the second sealing element 10b is monitored during operation. In one embodiment, the pressure is monitored in real time or intermittently. In one embodiment, the pressure is monitored using a pressure sensor. In a further embodiment, the pressure is monitored by monitoring the amount of fluid, e.g., air, required to maintain the pressure. If the pressure, or the amount of fluid required to maintain the pressure, drops, the sealing element 10a, 10b in question may be too worn, in which case replacement of the sealing element will be scheduled in step 640. The pressure inside the first sealing element 10a and / or the second sealing element 10b is adjusted in step 610, also during operation, in one embodiment, e.g. based on operating conditions or based on the measurements in step 620.

[0038] In one embodiment, wear of the first sealing element 10a and / or the second sealing element 10b is monitored using an electrical circuit element 50a. In one embodiment, the wear monitor comprises an alarm that is triggered when the electrical circuit element 50a does not conduct, i.e., when the circuit is broken due to wear of the sealing element in question. In such a case, the sealing element is scheduled for replacement in step 640.

[0039] Without limiting in any way the scope, interpretation, or application of the claims set forth below, a technical effect of one or more of the exemplary embodiments disclosed herein is providing an effective seal for rotating and reciprocating shafts. Another technical effect of one or more of the exemplary embodiments disclosed herein is providing an effective seal in an alkaline environment. Another technical effect of one or more of the exemplary embodiments disclosed herein is allowing for adjustment and monitoring of sealing efficiency. Yet a further technical effect of one or more of the exemplary embodiments disclosed herein is a safer, more maintenance-free seal. Another technical effect of one or more of the exemplary embodiments disclosed herein is an improved seal life.

[0040] Where desired, different functions described herein may be performed in different orders and / or simultaneously with one another. Furthermore, where desired, one or more of the functions previously described may be optional or may be combined.

[0041] Various aspects of the invention are set out in the independent claims, but other aspects of the invention include other combinations of features from the described embodiments and / or dependent claims with features of the independent claims, and not only the combinations explicitly set out in the claims.

[0042] It should also be noted that although exemplary embodiments of the present invention are described hereinabove, these descriptions should not be considered in a limiting sense, rather there are several variations and modifications that can be made without departing from the scope of the present invention as defined in the appended claims.

Claims

1. A sealing device (100) for a shaft, comprising: at least a first sealing element (10a) disposed around said shaft (30); at least a second sealing element (10b) disposed around said shaft (30); Equipped with the first sealing element (10a) and the second sealing element (10b) comprise adjustable sealing elements; the first sealing element (10a) and the second sealing element (10b) each comprise an outer shell (14a, 14b) of elastic material and a hollow core (12a, 12b); The hollow cores (12a, 12b) of the first sealing element (10a) and / or the second sealing element (10b) are pressurized with a fluid for an adjustable sealing effect. A sealing device (100) for a shaft, comprising:

2. The sealing device of claim 1 , wherein the outer shells (14a, 14b) comprise an outer layer of braided material.

3. 3. The sealing device according to claim 1 or 2, wherein at least the first sealing element (10a) and / or the second sealing element (10b) comprises an electrical circuit element (50a) configured to be broken when the outer shell (14a, 14b) wears or tears.

4. 3. The sealing device according to claim 1 or 2, further comprising valves (18a, 18b) connected to inlets (16a, 16b) for supplying the fluid to pressurize the first sealing element (10a) and the second sealing element (10b), respectively.

5. The sealing device of claim 1 or 2, wherein the fluid comprises a gas such as air.

6. The sealing device according to claim 1 or 2, further comprising a fluid space (60) between at least the first sealing element (10a) and the second sealing element (10b).

7. The sealing device according to claim 6, wherein the pressure in the fluid space (60) is adjustable.

8. The sealing device of claim 1 or 2, wherein the shaft (30) comprises a shaft of a rotary filter unit.

9. Setting a first pressure within a first seal element (10a) disposed around a shaft (30); establishing a second pressure within a second sealing element (10b) disposed around the shaft (30); monitoring the pressure inside the first sealing element (10a) and / or the second sealing element (10b); adjusting the pressure inside the first sealing element (10a) and / or the second sealing element (10b) for an adjustable sealing effect; 3. A method for controlling a sealing device (100) for a shaft according to claim 1 or 2, characterized in that

10. 10. The method of claim 9, further comprising monitoring wear of the first sealing element (10a) and / or the second sealing element (10b) using an electrical circuit element (50a).

11. 10. The method of claim 9, further comprising scheduling replacement of the first sealing element (10a) or the second sealing element (10b) based on monitoring the pressure and / or monitoring the wear.

12. A rotary filter unit comprising a sealing device according to claim 1 or 2.

13. A control system for controlling a sealing arrangement according to claim 1 or 2, comprising a control device (500) connected to at least one measurement and actuator module (510a, 510b) for carrying out the method according to claim 9.

14. A computer program product comprising computer readable program code which, when executed by a processor, causes the computer to perform the method of claim 9.

15. A non-transitory memory medium comprising the computer program product of claim 14.

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