VALVE AND CLEANING METHOD

Description

[0001] The invention relates to a valve according to the preamble of claim 1 and a method according to the preamble of claim 10.

[0002] Valves of this type are used in plants for the production of food, beverages, pharmaceuticals and fine chemical products, as well as in biotechnology.

[0003] These applications require a hygienic valve design. In particular, thorough cleaning must be possible.

[0004] A type of valve known as a double-seat valve consists of two closing elements, each with its corresponding valve seat, that can be brought into sealing contact. A so-called leakage chamber is located between the closing elements. The challenge lies in reliably cleaning the valve seats. This is achieved in double-seat valves capable of seat cleaning. These valves are designed to lift one closing element from its corresponding valve seat while the other closing element remains in sealing contact. Cleaning fluid flows over the exposed valve seat, cleaning both the seat and the closing element. The fluid can then be drained away via the leakage chamber.

[0005] Such seat-cleanable double-seat valves are known in the prior art.

[0006] WO 2009 / 115255 A1 and EP 0 646 741 B1 disclose double-seat valves capable of being cleaned, in which a seal on a valve stem can also be exposed for cleaning in a single cleaning step. Both documents show such arrangements; EP 0 646 741 B1 additionally shows cleaning of the actuator-side seal, which is designed to slide on a closing element section. An even older document is DE 41 18 874 A1, which also shows cleaning of the actuator-side seal.

[0007] In EP 0 646 741 B1, the cleaning position for the aforementioned seal is linked to the cleaning position of the main seals on the valve seats. The actuator, operated by a pressure medium, is therefore designed to perform a partial stroke in addition to the full or main stroke. DE 41 18 874 A1 and WO 2009 / 115255 A1 do not provide further details regarding the actuators.

[0008] Double-seat valves with seat cleaning capability can be designed as so-called tank bottom valves, with which the outlet of a tank can be connected to a piping system. WO 2019 / 020361 A1 proposes such a tank bottom valve.

[0009] From DE 10 2011 103 371 A1, a valve and a method for operating a valve are known in which a leakage chamber located between a first closing element and a second closing element is used in an operating mode as part of a product path between a first or second port and a third port of the valve, so that product or a product component is guided through the leakage chamber. For this purpose, the first closing element can be disengaged at its first closing element seat while the second closing element remains in sealing contact at its second closing element seat, or the second closing element can be disengaged at its second closing element seat while the first closing element remains in sealing contact at its first closing element seat. Consequently, for the aforementioned operating mode, the first or second closing element can be pulsed or vented.

[0010] Other double-seat tank bottom valves are known from WO 93 / 16307 A1 and WO 2004 / 063609 A1. These tank bottom valves are designed in the conventional manner for seat cleaning.

[0011] The purpose of the invention was now to improve the cleanability of the valve and to present a cleaning method.

[0012] This problem is solved by a valve having the features of claim 1 and a method having the features of claim 10.

[0013] The invention is based on the realization that, from a process engineering perspective, not only the known cleaning positions are available for cleaning the valve. Contrary to the prior art, it is also possible to clean parts in an open position of the valve that were previously inaccessible in this switching position. It is therefore proposed to open an intermediate space, surrounded by a first and a second closing element, towards the interior of the valve. This intermediate space, also called a leakage chamber, serves to drain and visualize leakage that can occur due to wear of the seals on the closing elements. The opening of the intermediate space to the interior is achieved by a gap between the first and second closing elements.Therefore, the adjusting device for the closing elements is designed to create an additional gap between the closing elements when they are simultaneously lifted from their respective valve seats. This provides a powerful cleaning flow, resulting in an unprecedented level of cleaning of the gap and the closing elements. This is particularly advantageous in so-called tank bottom valves, as a low pressure of the cleaning fluid is regularly observed in this application, entering through the valve connection to which the tank is connected.

[0014] In a first further development, the adjusting device is provided with an assembly that interacts with one of the closing elements and adjusts it in the open position relative to another closing element, thereby creating the gap. An additional assembly, specifically designed for this functionality within the adjusting device, allows for optimal implementation of this novel cleaning position. This assembly enables the adjusting device to be configured for optimal control of the closing elements, particularly with regard to the gap width. The switching forces can also be optimized. Possible operating principles for this assembly include those based on prior art electromagnetic, hydraulic, or pneumatic principles.

[0015] According to a further development, it is advantageous to provide the assembly with a piston which can be acted upon with a pressure medium, for example air, and which, under the pressure medium actuation, effects the additional position according to claim 1 by means of position shift.

[0016] A cost-effective and reliable design involves having the piston interact with a shoulder on one of the valve stems of a closing element. When pressurized, the piston engages with the shoulder, so that the valve stem is moved along with the piston.

[0017] Advantageously, an adjusting device designed to adjust the closing elements can be modularly designed with at least two drive modules, one of which is configured to effect the additional cleaning position. This is cost-effective to manufacture and also allows for adjustments at the customer's site, i.e., in the process plant. The drive modules are preferably detachably coupled to one another and arranged in a row.

[0018] When constructing the adjustment device from drive modules, it is advantageous to arrange the assembly in a separate drive module. The design is preferably chosen such that this drive module can be retrofitted into the adjustment device. For this purpose, it can include its own sections of valve rods that can be coupled to the rods of the valve and the other drive modules.

[0019] The advantages of modularity can be increased if the adjusting device includes a drive module that controls the closing elements to move them into a position corresponding to the open position of the valve.

[0020] A simple, cost-effective design of the actuator modules is possible if the actuator module comprising the assembly is positioned between the valve housing and the actuator module that generates the valve's open position. This eliminates the need for modifications to previously known actuator modules for the open position.

[0021] The advantages of modularity are enhanced and achieved cost-effectively, particularly enabling easy retrofitting, if at least one of the valve stems, preferably all valve stems, is constructed in multiple parts. The multi-part construction is chosen to support modularity. This is the case, for example, if the valve stem components extend only across individual actuator modules.

[0022] The method according to claim 10 provides for lifting both closing elements from their associated valve seats, simultaneously forming a gap between the closing elements that connects the space between and the interior. In this way, the cleaning method is extended to include a position of the closing elements in which a cleaning agent is introduced into the valve, thus effecting a complete cleaning.

[0023] The invention will be explained in more detail using an exemplary embodiment and its further developments. Furthermore, the advantages will be presented in greater depth.

[0024] They show: Fig. 1 : A double seat valve in tank bottom design in the open position; Fig. 2 : The double seat valve according to the example with an additional cleaning position in the cutout; Fig. 3 : Adjustment device for the double seat valve as shown in the example.

[0025] In Fig. 1 Figure 1 shows a longitudinal section through a valve 1 that can be connected to and cleaned by a tank.

[0026] The valve 1 comprises a one-piece or multi-piece housing 2 with a first port 3, which can be connected to a tank or container (not shown). This connection can be made by means of a clamping flange or a welded joint. A second port 4 is formed on the housing 2, which can be connected to a pipeline of a process plant. A third port 5 is provided and can be connected to a leak detection and / or drainage device. The housing defines an interior space 6, which connects the first and second ports 3 and 4 in a fluid-carrying manner. A passage 7 is formed in the housing between the first and second ports 3 and 4.

[0027] Inside there is a first locking element 8 and a second locking element 9.

[0028] The first closing element 8 interacts with a first valve seat 10, which is designed as a cylindrical surface in the passage 7. On a side of the first valve seat 10 facing the interior 6, a second valve seat 11 is formed, which is preferably stepped. Due to its stepped shape, the second valve seat 11 forms an axial stop that limits the movement of the second closing element 9.

[0029] The second closing element 9 is cup-shaped. Inside it is a space 12. The first closing element 8 is accommodated in the second closing element 9 in such a way that the space 12 is sealed against the interior 6. A channel 13 is formed in the second closing element 9 on a side facing away from the first closing element 8 and creates a fluid connection between the space 12 and the third port 5. Cleaning fluid or leakage from leaks between valve seats and closing elements first enters the space 12 and then flows through the channel 13 to the third port 5.

[0030] The locking elements 8 and 9 can be moved by means of an adjusting device 20.

[0031] The adjusting device 20 is advantageously modular in design and has several drive modules, which in this example are pressure-medium operated and partially spring-loaded.

[0032] A first valve rod 21 is connected to the first closing element 8 and is slidably arranged in a second valve rod 22, which is designed as a hollow rod. This second valve rod 22 is connected to the second closing element 9.

[0033] The adjusting device 20 comprises a first drive module 23 in which a first piston 24 is arranged. This piston interacts with the first valve stem 21. The first drive module 23 allows the first closing element 8 to be moved back and forth between two positions. In the first position, the first closing element 8 is in sealing contact with the first valve seat 10. In the second position, after moving towards the adjusting device 20, the closing element 8 is in a retracted position within the interior 6. The second closing element 9 is moved along with it during this movement, and the valve 1 is then in an open position, in which a flow connection exists between the first and second ports 3 and 4.

[0034] The adjusting device 20 comprises a second drive module 25, which is detachably connected to the first drive module 23, and in which a second piston 26 is arranged, which interacts with the first valve stem 21. When this piston is actuated with a pressure medium, the second piston 26 exerts a force on the first valve stem 21 and causes the first valve stem 21 to be displaced in the direction of the first port 3. This causes the first closing element 8, which is connected to the first valve stem 21, to be lifted from the first valve seat 10 to a side of the first valve seat 10 facing away from the interior 6. This position allows for cleaning, in particular of the first valve seat 10. The second closing element 9 is in sealing contact with the second valve seat 11 to which it is assigned. The fluid used for cleaning now flows through the space 12, then through the channel 13, and exits the valve through the third port 5.

[0035] The second drive module 25 incorporates a third piston 27. This piston interacts with the second valve stem 22. The third piston 27 and the second valve stem 22 are configured such that when the third piston 27 is pressurized, the second closing element 9 is vented from the second valve seat 11 into the interior 6. The first closing element 8 remains in sealing contact with the first valve seat 10. This position of the closing elements 8 and 9 allows for cleaning, particularly of the second valve seat 11. The cleaning fluid is also discharged through the space 12, channel 13, and third port 5.

[0036] The adjusting device 20 comprises a third drive module 28, which is detachably connected to the second drive module 25 and has a fourth piston 29. To create an additional cleaning position, this piston can be pressurized with a pressure medium if the first piston 24 has already been pressurized. However, the first piston 24 can be pressurized without actuating the fourth piston 29. By pressurizing the first piston 24, the first and second closing elements 8 and 9 are lifted from the first and second valve seats 10 and 11 and moved into the interior 6. When pressurized, the fourth piston 29 engages the second valve stem 22 and moves it, and thus indirectly the second closing element 9, towards the adjusting device 20.This creates a gap between the first and second closing elements 8 and 9, which allows a cleaning agent to enter from the interior 6 into the space 12. A particularly powerful cleaning flow is available, ensuring that in this position of the first and second closing elements 8 and 9, all product-contacting surfaces of the valve 1, including the interior 6 and the space 12, are thoroughly cleaned. The valve 1 thus significantly surpasses the hygienic properties of previous state-of-the-art valves.

[0037] The modular design of the adjusting device 20, presented in this example, with its three drive modules 23, 25, and 28, allows for cost-effective adaptation of the valve arrangement to customer requirements. In particular, retrofitting the third drive module 28 with the additional cleaning position is also possible on existing systems and their valves.

[0038] The valve 1 can additionally include a spray nozzle 30, which is arranged in the second closing element 9 and surrounds the first valve stem 21 as it exits the second valve stem 22. This spray nozzle 30 can be supplied with cleaning fluid through a gap between the first and second valve stems 21 and 22.

[0039] The appropriate pressure application to the pistons 24, 26, 27, and 29 can advantageously be achieved by a control head 31 equipped with pressure-control valves, which is attached to the valve 1. The pressure-control valves are configured according to requirements transmitted by a plant control system to the electronics of the control head 31. The control head 31 can include a measuring device that determines the position of a measuring target 32 ​​arranged on the first valve stem 21. From this, the position of the first and second closing elements 8 and 9 can be inferred. This information can be transmitted to the plant control system.

[0040] In Fig. 2 The additional cleaning position of valve 1 is illustrated in a detailed view. The first closing element 8 and the second closing element 9 are retracted into the interior 6 and open the passage 7, allowing fluid to flow between the first port 3 and the second port 4.

[0041] The first valve seat 10, which in the closed position of the valve 1 is in sealing contact with a first seal 81 provided on the first closing element 8, is exposed in this position of the valve 1. Likewise, the second valve seat 11, which in the closed position of the valve 1 is in sealing contact with a second seal 91 provided on the second closing element, is now also exposed. Advantageously, the first seal 81 can be designed as a radial seal and the second seal 91 as an axial seal. In particular, the radial design of the first seal 81 allows the first closing element 8 to be moved beyond the passage 7 into the first port 3 and into the second closing element 9.

[0042] In the regular open position of the valve 1, the first and second closing elements 8 and 9 are also retracted into the interior 6, and the passage 7 is open, thus allowing fluid to pass through. However, in the open position, the first seal 81 is in sealing contact with an internal seat 92 provided on the second closing element 9. This seat is designed such that the interior 6 and the space 12 in the second closing element 9 are fluidically separated from each other.

[0043] In the Fig. 2In the position shown, however, the first closing element 8 and the second closing element 9 are displaced relative to each other such that the passage 7 is opened, but the first seal 81 is not in sealing contact with the inner seat 92. A gap S is formed between the first and second closing elements 8 and 9, which allows fluid flow. The gap width can advantageously be dimensioned such that the resulting flow through the gap S cleans the first seal 81 and the inner seat 92, as well as the surfaces of the first and second closing elements 8 and 9 adjacent to the seal and seat. It is advantageous that the second closing element 9 is positioned according to Fig. 2 in the direction of the adjusting device 20, in Fig. 2 to move downwards, and thus away from passage 7, thereby releasing the second closing element. This improves the cleaning result.

[0044] The construction of the adjusting device 20 of this example is shown in Fig. 3 A more detailed explanation.

[0045] The first actuation module 23, which moves the valve 1 into an open position by displacing the first and second closing elements 8 and 9 into the interior 6, comprises the first piston 24. The first piston 24 is mounted on an actuating rod 231, so that movement of the first piston 24 results in movement of the actuating rod 231. Movement of the first piston 24 can be effected by applying a pressure medium. The first piston 24 is displaced by applying a pressure medium, for example, compressed air, against the force of a spring 232 or a spring assembly. The displacement of the first piston 24 occurs in sliding contact with a first running surface 233, which can be shaped as a cylindrical surface. The displacement is limited by a first stop 24. The first stop 24 can be designed as a circumferential projection, which can be configured as an annular component.

[0046] The second drive module 25 is arranged on and connected to the first drive module 23 on a side facing the locking elements 8 and 9 and the housing 2. The connection is advantageously designed to be detachable, thus making the second drive module 25 a separate commercial unit.

[0047] In the second drive module 25, the second piston 26 is slidably arranged. The displacement occurs in sliding contact with a second running surface 251. Also slidably arranged in the second drive module 25 is the third piston 27, which is in sliding contact with a third running surface 252. Both pistons 26 and 27 can be pressurized to effect the displacement. Pressurizing one of the pistons 26 and 27 causes it to move in the direction of the other piston. A second stop 253 is provided between the pistons 26 and 27 and the running surfaces 251 and 252. This stop is designed as a ring-shaped component and forms a projection for each of the cylindrical running surfaces 251 and 252. In this way, one component forms the movement limit for both pistons 26 and 27.

[0048] The second drive module 24 is configured to move one of the closing elements 8 and 9 into a cleaning position in which one of the closing elements is lifted from its associated valve seat 10 or 11, while the other closing element 8 or 9 remains in sealing contact. For this purpose, the second running surface 251 and the second stop 253 are dimensioned to allow a longer travel distance for the second piston 26 than for the travel distance of the first piston 24. The drive rod 231 is slidably mounted in a sliding bushing 254, which is provided in a hub 255 of the second piston 26. By moving the first piston 24, the first closing element 8 is brought into contact with the first valve seat 10. The second piston 26 is moved along with it.Pressurizing the second piston 26 moves it to the second stop 253 and, via the second valve rod 22, pushes the first closing element out of the first valve seat 10 into the first port 3. In doing so, the drive rod 231 is pulled out of the sliding bushing 254 a short distance.

[0049] The cleaning position of the second closing element 9 is effected by the third piston 27, which is pressurized with hydraulic fluid and thereby moved towards the second piston 26. The third piston 27, which is slidably arranged in sliding contact on the second valve stem 22, comes into contact with a fourth stop 257, which is formed at the end 256 of the second valve stem. This causes the second valve stem 22 to move along with it until the third piston 27 reaches the second stop 253. The movement of the second valve stem 22 thus triggered lifts the second closing element 9 from the second valve seat 11.

[0050] In the third drive module 28, the fourth piston 29 is slidably arranged on the second valve rod 22 and interacts with a fourth running surface 281 provided on a housing. A shoulder 282 is formed on the second valve rod 22, which acts as a stop for the fourth piston 29. When the fourth piston 29 is pressurized, it moves towards the other drive modules 24 and 25 until it reaches a housing-side travel limit 283. Before reaching this travel limit 283, the fourth piston 29 engages with the shoulder 282 and consequently moves the second valve rod 22 with it. This causes the closing elements 8 and 9 to move as described in the open position of the valve 1. Fig. 2 shown, moved apart until the desired gap S was set.

[0051] The modularity of the design is improved if at least one of the valve rods 21 and 22, preferably both, are made up of multiple parts, wherein the

[0052] Rod sections are preferably assigned to the individual modules 23, 25 and 28.

[0053] This modular design of the adjusting device 20 is advantageous because individual functions, such as cleaning positions for the individual locking elements, can be retrofitted by adding the second drive module 25. The additional cleaning position, achieved by the third drive module 28, can also be retrofitted. In this way, production costs can be reduced, and customer needs can be specifically met by tailoring the adjusting device 20 to the customer's requirements.

[0054] The invention was described using the example of a tank bottom valve, but is also applicable to valves according to WO 2009 / 115255 A1. Reference symbol list

[0055] 1 Valve 2 Housing 3 First connection 4 Second connection 5 Third connection 6 Interior 7 Passage 8 First closing element 9 Second closing element 10 First valve seat 11 Second valve seat 12 Intermediate space 13 Channel 20 Adjusting device 21 First valve stem 22 Second valve stem 23 First actuator module 24 First piston 25 Second actuator module 26 Second piston 27 Third piston 28 Third actuator module 29 Fourth piston 30 Spray nozzle 31 Control head 32 Measuring target 81 First seal 91 Second seal 92 Inner seat 231 Actuator rod 232 Spring assembly 233 First running surface 234 First stop 251 Second running surface 252 Third running surface 253 Second stop 254 Sliding bushing 255 Hub 256 End of the second Valve stem 257 fourth stop 281 fourth running surface 282 shoulder 283 travel limiter Split

Claims

1. A valve (1) with a housing (2), which delimits an interior space (6), a first connection (3), a second connection (4), a passage (7), which connects the first connection (3) to the second connection (4) in a fluid-conducting manner, a first closing member (8) and a second closing member (9), which closing members (8, 9) are accommodated in the interior space (6) and surround an intermediate space (12), which is connected to a third connection (5), and an adjusting device (20), which is configured to bring the first closing member (8) into sealing contact with a first valve seat (10) formed in the passage (7) and to bring the second closing member (9) into sealing contact with a second valve seat (11) formed in the passage in a closed position and to release the first and second closing members (8, 9) from the first and second valve seats (10, 11) in an open position, wherein the first closing member (8) is accommodated in the second closing member (9) in a sealing manner, characterized in that the second closing member (9) is cup-shaped, wherein the intermediate space (12) is located inside it, wherein the first closing member (8) can be accommodated in the second closing member (9) such that the intermediate space (12) is sealed with respect to the interior space (6), and in that the adjusting device (20) is configured to form a gap (S) between the first and second closing members (8, 9) that connects the intermediate space (12) to the interior space (6) when at the same time the first and second closing members (8, 9) are lifted from the first and second valve seats (10, 11) by the adjusting device (20).

2. The valve according to claim 1, characterized in that the adjusting device (20) comprises an assembly (28) that interacts with one of the closing members (8, 9) and adjusts said closing member in relation to another closing member (8, 9) while forming the gap (S) in the open position.

3. The valve according to claim 2, characterized in that the assembly (28) comprises a piston (29) to which a pressure medium can be applied.

4. The valve according to claim 3, characterized in that the piston (29) interacts with a shoulder (282) on a valve rod (22) of the closing member (9).

5. The valve according to one of claims 2 to 4, characterized in that the adjusting device (20) comprises at least two drive modules (23, 25, 28).

6. The valve according to claim 5, characterized in that the assembly is arranged in an independent drive module (28).

7. The valve according to claim 5 or 6, characterized in that the adjusting device (20) comprises a drive module (23) generating the open position of the valve (1).

8. The valve according to claim 7, characterized in that the drive module (28) comprising the assembly is arranged between the housing (2) and the drive module (23) generating the open position.

9. The valve according to one of claims 5 to 8, characterized in that at least one valve rod (21, 22) of the valve (1) is designed in several parts.

10. A cleaning method for a valve (1), which has an intermediate space (12) that can be separated from an interior space (6) by a first closing member (8) and a second closing member (9) and which has a first valve seat (10) associated with the first closing member (8) and a second valve seat (11) associated with the second closing member (9), and the first closing member (8) is brought into sealing contact with the first valve seat (10) and the second closing member (9) is brought into sealing contact with the second valve seat (11) in a closed position of the valve (1), characterized in that the second closing member (9) is cup-shaped, wherein the intermediate space (12) is located inside it, wherein the first closing member (8) can be accommodated in the second closing member (9) such that the intermediate space (12) is sealed with respect to the interior space (6), and in that the first closing member (8) is brought into a position in which it is lifted from a first valve seat (10) and the second closing member (9) is brought into a position in which it is lifted from a second valve seat (11) and at the same time a gap (S) is formed between the first closing member (8) and the second closing member (9), which gap connects the intermediate space (12) to the interior space (6).