Hydraulic or pneumatic actuators for steam turbine or turboexpander trip valves

Abstract

A hydraulic or pneumatic actuator (100, 200) for a valve, in particular a trip valve, that can be used to shut off the fluid supplied to an expander when a fault occurs, for example when the pressure drops below a predetermined pressure value. The innovative actuator has a movable plate (30) with a first side (31) associated with the spindle of the valve through a rod (21) and a second side (32) associated with a spring (40) configured to move the movable plate. The actuator is provided with a test system (50) configured to measure the elastic force of the spring without partially or fully closing the valve in order to check the correct condition of the spring.

Description

[Technical Field]

[0001] The subject matter disclosed herein relates to hydraulic or pneumatic actuators for opening and closing valves, particularly trip valves. More specifically, the subject matter disclosed herein relates to hydraulic or pneumatic actuators for valves that allow the operating capacity of the valve to be tested without shutting down the machine in which it is installed. [Background technology]

[0002] Currently, steam turbines, or more generally turboexpanders, are typically provided with trip valves upstream of the fluid inlet of the machine in order to shut off the fluid supplied to the expander within the shortest possible time, which is particularly important in case of malfunction.

[0003] Typically, a trip valve is provided with an actuator including a valve spindle configured to close a fluid inlet of a machine and a spring. Generally, trip valves are opened hydraulically or pneumatically, for example, using pressurized water, oil, or other suitable fluid, and closed by spring force. The actuator includes a housing containing a sliding plate mechanically coupled to the valve spindle and a spring mechanically coupled to the sliding plate, with one side of the sliding plate fluidically coupled to a chamber containing pressurized fluid, typically pressurized oil, and the other side of the sliding plate mechanically coupled to the spring, which is preloaded (i.e., compressed) in a pre-operational state. Thus, the sliding plate is subjected to a first force from the pressurized fluid and a second (and opposite) force from the spring. In an operational state, when fluid is evacuated from the chamber and the fluid pressure drops below a predetermined value, the first force is no longer sufficient to hold the spring in its compressed position, and a sudden release of energy stored in the spring moves the sliding plate to close the valve spindle.

[0004] To ensure accurate valve operation during valve operating conditions, the actuator is periodically checked. For example, during pre-operational conditions, the sliding plate may be moved a certain amount to verify that it and the valve spindle can slide when subjected to a specific design pressure while the expander is in operation. However, known hydraulic or pneumatic actuators do not provide the ability to check the condition and full functionality of the springs without partially or completely closing the machine's fluid inlet, which can affect the performance of the expander or even require the expander to be shut down as a result of the test.

[0005] It is therefore desirable to have an actuator for a trip valve that allows the correct condition of the spring to be checked without partially or completely closing the trip valve. Summary of the Invention

[0006] According to one aspect, the subject matter disclosed herein is a hydraulic or pneumatic actuator for a valve, particularly a trip valve, housed within a cylinder having a lateral wall, a first end wall, and a second end wall, a first rod slidably and partially housed within the cylinder and having a first end configured to be mechanically coupled to a spindle of the valve; a first plate slidably received within the cylinder and configured to define a first variable volume chamber, the first plate having a first side mechanically coupled to the second end of the first rod; and - a hydraulic or pneumatic actuator comprising: a resilient element housed within a cylinder and having a first end mechanically coupled to a second side of the first plate and a second end mechanically coupled to a second end wall of the cylinder. The elastic element is configured to apply a first force to the first plate and a second force to the second end wall, the second force being equal and opposite to the first force, to move the first plate. The actuator further comprises a test system configured to measure the second force or a third force related to the second force.

[0007] According to another aspect, the subject matter disclosed herein is a turboexpander system comprising: - hydraulic or pneumatic actuator with spring and test system; - a turbo expander machine; a valve, in particular a trip valve, mechanically coupled to an actuator and fluidly coupled to a fluid inlet of the turboexpander machine. The valve is configured to be actuated by a hydraulic or pneumatic actuator to stop the fluid supply to the fluid inlet, and the test system is configured to check the correct state of the spring without actuating the valve, i.e. without fully or partially closing the valve. [Brief explanation of the drawings]

[0008] A more complete understanding of the disclosed embodiments of this invention and many of the attendant advantages thereof will be readily obtained as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

[0009] [Figure 1] 1 shows a cross-sectional view of a first embodiment of the innovative actuator in a pre-operational stage. [Figure 2] 1 shows a cross-sectional view of a second embodiment of the innovative actuator in a pre-operational stage. [Figure 3] 2 shows the embodiment of FIG. 1 in an operational stage. [Figure 4] 2 shows the embodiment of FIG. 1 in a preliminary stage. [Figure 5]3 shows a turboexpander system including the innovative actuator of FIG. 1 or FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0010] According to one aspect, the subject matter disclosed herein relates to an innovative actuator for a valve, particularly a trip valve, that can be used to shut off fluid supplied to an expander when a fault occurs, for example, when the pressure drops below a predetermined pressure value. The innovative actuator can be a hydraulic or pneumatic actuator having a movable plate with a first side associated with the valve's spindle through a rod and a second side associated with a spring configured to move the movable plate. In particular, when the valve is in an open configuration, the elastic force of the spring is counteracted by the pressure of a fluid, e.g., oil, acting on the first side of the movable plate. When the fluid pressure drops, the elasticity of the spring can overcome the fluid pressure, and the plate is then moved in conjunction with the valve's spindle to quickly close the valve. The innovative actuator is provided with a test system configured to measure the elastic force of the spring without partially or fully closing the valve to check the correct state of the spring and therefore its ability to close the valve correctly and quickly.

[0011] According to another aspect, the subject matter disclosed herein relates to a turboexpander system including an innovative actuator.

[0012] Next, embodiments of the present disclosure will be described in detail, examples of which are illustrated in the drawings. The examples and drawings are provided as an explanation of the present disclosure and should not be construed as limiting the present disclosure. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the scope or spirit of the present disclosure. In the following description, like reference numerals are used in the illustrations of the embodiment figures to indicate elements that perform the same or similar functions. Moreover, for clarity of illustration, some reference numerals may not be repeated in all figures.

[0013] 1 shows a simplified cross-sectional view of a first embodiment of an innovative actuator for a valve, in particular a trip valve, generally designated by the reference number 100. The actuator 100 is housed in a cylinder 10, which comprises a lateral wall 13, a first end wall 11 and a second end wall 12. Advantageously, as will be better explained below, at least the first end wall 11, and possibly the second end wall 12, have a hole, in particular a central hole, through which a rod can slide.

[0014] 1 , the actuator 100 comprises a first rod 21 slidably partially housed within the cylinder 10. Advantageously, the first rod 21 is configured to have a first portion that passes through a hole in the first end wall and is housed within the cylinder 10, and a second portion that protrudes from the cylinder 10 (it should be noted that the size of the portion inside the cylinder and the portion outside the cylinder may vary depending on the sliding position of the rod). The first rod 21 has a first end configured to be mechanically coupled to a spindle of the valve, and a second end that is mechanically coupled to a first plate 30, in particular to a first side surface 31 of the first plate 30.

[0015] The first plate 30 is configured to be slidably received within the cylinder 10 and to define a first variable volume chamber 35 between the first side surface 31 and the first end wall 11; advantageously, the first variable volume chamber 35 is configured to be filled with a fluid, in particular a pressurized fluid. With non-limiting reference to Figures 1 and 2, advantageously, the actuators 100 and 200 further comprise a second fluid circuit 62 configured to supply a fluid to the first variable volume chamber 35. In particular, the fluid supplied to the first variable volume chamber 35 is configured to apply a pressure (hereinafter referred to as a "fifth force") to the first plate 30. As will be better explained below, the position of the first plate 30 within the cylinder 10 depends on the volume of the first variable volume chamber 35.

[0016] The first plate 30 further has a second side 32 opposite the first side 31, which is mechanically coupled to a resilient element 40, such as one or more helical springs, cup springs, or any other type of spring, suitable for performing the same function as taught herein. In particular, the resilient element 40 is housed inside the cylinder 10. The resilient element 40 further has a second end that is mechanically coupled to the second end wall 12 of the cylinder 10; it should be noted that, as will become apparent below, the resilient element 40 may be directly or indirectly coupled to the second end wall 12. The resilient element 40 is configured to apply a first force to the first plate 30 and a second force to the second end wall 12, the second force being equal and opposite to the first force, to move the first plate 30. The innovative hydraulic actuators 100 and 200 further comprise a test system 50 for measuring a second force applied by the elastic element 40 or a third force related to the second force and better described below.

[0017] It should be noted that when the first variable volume chamber 35 is filled with pressurized fluid at a certain pressure, the first force applied by the elastic element 40 to the second side 32 of the first plate 30 is counteracted by the pressure of the fluid on the first side 31 of the first plate 30, so that the first plate 30 (and therefore the first rod 21) does not move (this can be referred to as the "pre-operation phase"; see, for example, Figures 1 and 2). However, when the pressure inside the first variable volume chamber 35 is reduced, for example by draining fluid from the first variable volume chamber 35, the first force on the second side 32 becomes greater than the pressure on the first side 31, so that the first plate 30 (and therefore the first rod 21) can be pushed by the elastic element 40 and move (this can be referred to as the "operation phase"; see, for example, Figure 3).

[0018] 1 and 2, the test system 50 comprises a second plate 51 located between the elastic element 40 and the second end wall 12, and in particular, the second plate 51 is mechanically coupled to the second end of the elastic element 40. Advantageously, the second plate 51 is configured to press (directly or indirectly) against the second end wall 12 with a second force.

[0019] 1, the testing system 50 further comprises a second rod 52 slidably and partially housed inside the cylinder 10 and mechanically coupled to the second plate 51. Advantageously, the second rod 52 is configured to partially protrude from the second end wall 12, for example through a hole in the second end wall 12. In particular, the portion of the second rod 52 protruding from the second end wall 12 may vary depending on the force applied to the second plate 51.

[0020] 1 , the test system 50 further comprises a first fluid circuit 61 and a second variable volume chamber 55 located between the second plate 51 and the second end wall 12. According to a first possibility, the second variable volume chamber 55 is defined by the second plate 51 and the second end wall 12. Advantageously, the first fluid circuit 61 is configured to supply a fluid, in particular a pressurized fluid, into the second variable volume chamber 55 through the lateral wall 13 of the cylinder. It should be noted that when the second variable volume chamber 55 is filled with a fluid at a certain pressure, the supplied fluid is configured to apply a fourth force to the second plate 51 in order to move the second plate 51, in particular to move the second plate 51 away from the second end wall 12. Advantageously, the second plate 51 is configured to move when the fourth force acting on the second plate 51 by the fluid is greater than the second or third force by the elastic element 40, particularly when it is greater in absolute value.

[0021] Advantageously, the portion of the second rod 52 that protrudes from the second end wall 12 varies depending on the fourth force acting on the second plate 51. It should be noted that the fourth force acting on the second plate 51 is opposite to the second or third force acting on the second plate 51 by the elastic element 40. By measuring the portion of the second rod 52 that protrudes from the second end wall 12 in dependence on the fourth force (and therefore on the pressure of the fluid in the second variable volume chamber 55), the elastic force of the elastic element 40 can be measured without moving the first plate 30, i.e. without moving the spindle of the valve to fully or partially close the valve.

[0022] Advantageously, and with non-limiting reference to Figures 1 and 2, the actuators 100 and 200 further comprise a cup 80, which is particularly advantageous for increasing the speed of actuation of the valve, in particular the speed of movement of the first plate 30. The cup 80 has a lateral wall and an end wall mechanically connected to one another, the lateral wall being arranged such that an edge of the lateral wall abuts the second side of the first plate 30 to define an internal chamber 45, in particular a closed internal chamber 45. Advantageously, a resilient element 40 is housed within the internal chamber 45, the second end of the resilient element 40 being mechanically coupled to the end wall of the cup 80. In other words, the end wall of the cup 80 is located between the second plate 51 and the second end wall 12, and the second variable volume chamber 55 is defined by the second plate 51 and the end wall of the cup 80. According to this possibility, the elastic element 40 is configured to apply a third force to the end wall of the cup 80, the third force being in particular a force acting on the end wall of the cup equal to and opposite to the first force acting on the first plate 30.

[0023] Advantageously, a portion of the first fluid circuit 61 traverses the lateral wall of the cup 80 in order to supply fluid, in particular pressurized fluid, to the second variable volume chamber 55. According to the example shown in Fig. 1, a first portion of the first fluid circuit 61 traverses the lateral wall 13 of the cylinder 10 and is configured to supply fluid to a gap or chamber located between the lateral wall 13 of the cylinder 10 and the lateral wall of the cup 80, and advantageously a second portion of the first fluid circuit 61 traverses the lateral wall of the cup 80 in order to be fluidly coupled to the gap or chamber and the second variable volume chamber 55 and thus to be able to supply fluid to the second variable volume chamber 55. Advantageously, at least one seal 54 is located between the lateral wall 13 of the cylinder 10 and the lateral wall of the cup 80, in particular the at least one seal 54 is arranged around the first fluid circuit 61 in order to fluidically isolate the gaps or chambers.

[0024] The second embodiment shown in FIG. 2 is similar to the first embodiment shown in FIG. 1 , but differs from the test system 50 of the actuator 100 in that the test system 50 of the actuator 200 includes at least one load sensor 70, which may be, by way of non-limiting example, a load cell or a strain gauge, configured to measure the second or third force exerted by the elastic element 40. In particular, the at least one load sensor 70 may be mounted on the second plate 51, mounted on the second end wall 12, or positioned between the second plate 51 and the second end wall 12, e.g., on an end wall of the cup 80. Advantageously, the test system 50 includes a set of load sensors 70 configured to ensure stable support of the second plate 51; for example, the test system may have three load sensors 70 spaced apart, e.g., positioned 120° from each other. In particular, each load sensor 70 is configured to measure a portion of the second or third force. It should be noted that the measurement of the second or third force may be performed continuously or as desired. The load sensor 70 can be a wireless sensor (as shown in the embodiment of FIG. 2) or a wired sensor; in the case of a wired sensor requiring electrical wiring, the wires can be passed through a rigid rod (similar to the rod 52 shown in the embodiment of FIG. 1) to direct the signal outside the cylinder 10.

[0025] As already mentioned above, the cup 80 is particularly advantageous for increasing the speed of actuation of the valve, in particular the speed of movement of the first plate 30. Indeed, with non-limiting reference to Figure 3, when the actuator moves from the pre-operation stage to the operation stage, i.e. when the first force acting on the first plate 30 by the elastic element 40 becomes greater than the fifth force acting on the first plate 30 by the fluid in the first variable volume chamber 35, the first plate 50 starts to move away from the lateral wall edge of the cup 80. Advantageously, fluid can leak from the first variable volume chamber 35 into the internal chamber 45, causing a more rapid pressure drop in the first variable volume chamber 35 and therefore a more rapid drop in the fifth force acting on the first plate 30.

[0026] Furthermore, the cup 80 is also advantageous, for example, in the "warm-up phase" of the actuators 100 and 200. With non-limiting reference to Figure 4, which shows the embodiment shown in Figure 1 after passing from the pre-operation phase to the operation phase (see, for example, Figure 3) and then from the operation phase to the warm-up phase, the actuator 100 can take over the pre-operation phase by moving the cup 80 so that the lateral wall edge of the cup 80 abuts the first plate 30 (thus simultaneously loading the elastic element 40) once the valve closes (operation phase), i.e., once the first plate 30 reaches the end of its stroke, for example by abutting the first end wall 11, and then moving the cup 80 and the first plate 30 together back to the pre-operation phase position. Advantageously, the movement of the cup 80 can be performed by supplying fluid, in particular pressurized fluid, to the third variable volume chamber 65, for example through the third fluid circuit 63. It should be noted that the third fluid circuit 63 may be fluidly coupled to the first fluid circuit 61 or the second fluid circuit 62. In particular, the third variable volume chamber 65 is defined between an end wall of the cup 80 and the second end wall 12 of the cylinder 10. When the lateral wall edge of the cup 80 abuts the first plate 30, the first variable volume chamber 35 is filled with fluid, in particular pressurized fluid, and preferably simultaneously the third variable volume chamber 65 is emptied of fluid, thereby allowing both the cup 80 and the first plate 30 to move back to their pre-operation positions.

[0027] According to another aspect, the subject matter disclosed herein relates to a turboexpander system (e.g., as shown in FIG. 5 ) comprising the innovative hydraulic or pneumatic actuators 100 and 200 described above. The system is illustrated in FIG. 5 . The system further comprises a turboexpander machine 300, e.g., a steam turbine, having a fluid inlet 301 for supplying fluid to the machine 300, and a valve 400, particularly a trip valve, fluidly coupled to the fluid inlet 301 and configured to be actuated by the actuators 100 and 200 to stop the fluid supply to the fluid inlet 301. The innovative hydraulic or pneumatic actuators 100 and 200 comprise a test system 50 configured to operate without actuating the valve 400, i.e., without fully or partially closing the fluid inlet 301 for supplying fluid to the machine 300, and particularly to measure the elastic force of the elastic element 40 of the actuators 100 and 200.

Claims

1. A hydraulic or pneumatic actuator (100, 200) for a valve, in particular a trip valve, housed in a cylinder (10) with a lateral wall (13), a first end wall (11) and a second end wall (12), a first rod (21) slidably and partially housed inside said cylinder and having a first end adapted to be mechanically coupled to a spindle of said valve; a first plate (30) slidably received within the cylinder (10) and having a first side (31) and a second side (32), the first side (31) being mechanically coupled to the second end of the first rod (21) and configured to define a first variable volume chamber (35) between the first side (31) and the first end wall (11); a resilient element (40) housed within the cylinder (10) and having a first end mechanically coupled to the second side (32) of the first plate (30) and a second end mechanically coupled to the second end wall (12) of the cylinder (10), the resilient element (40) being configured to apply a first force to the first plate (30) and a second force to the second end wall (12) to move the first plate (30), the second force being equal and opposite to the first force; The hydraulic actuator (100, 200) further comprises a test system (50) for measuring the second force or a third force related to the second force.

2. the test system (50) comprises a second plate (51) positioned between the elastic element (40) and the second end wall (12); The actuator (100, 200) of claim 1, wherein the second plate (51) is configured to press against the second end wall (12) with the second force.

3. the test system (50) further comprises a first fluid circuit (61) and a second variable volume chamber (55) located between the second plate (51) and the second end wall (12); the first fluid circuit (61) is configured to supply fluid to the second variable volume chamber (55); the supplied fluid is configured to apply a fourth force to the second plate (51) to move the second plate (51); 3. The actuator (100) of claim 2, wherein the second plate (51) is configured to move when the fourth force acting on the second plate (51) by the fluid is greater than the second or third force by the elastic element (40).

4. the test system (50) further comprises a second rod (52) mechanically coupled to the second plate (51); the second rod (52) is slidably and partially housed within the cylinder (10); The actuator (100) of claim 3, wherein the second rod (52) is configured to partially protrude from the second end wall (12).

5. 5. The actuator (100) of claim 4, wherein the portion of the second rod (52) protruding from the second end wall (12) is configured to change in response to the fourth force acting on the second plate (51).

6. the test system (50) further comprises at least one load sensor (70) mounted on the second plate (51), mounted on the second end wall (12), or located between the second plate (51) and the second end wall (12); The actuator (200) of claim 2, wherein the at least one load sensor (70) is configured to measure the second or third force exerted by the elastic element (40).

7. 7. The actuator (200) of claim 6, wherein the test system (50) comprises a set of load sensors (70), each configured to measure a portion of the second or third force, and the set of load sensors (70) configured to ensure stable support of the second plate (51).

8. 8. The actuator (200) of claim 6 or 7, wherein the measurement of the second or third force is performed continuously.

9. a cup (80) having a lateral wall and an end wall; The actuator (100, 200) of claim 1, wherein a lateral wall edge is configured to abut the second side of the first plate (30) and define an interior chamber (45).

10. The elastic element (40) is housed within the internal chamber (45), 10. The actuator (100, 200) of claim 9, wherein the second end of the resilient element (40) is mechanically coupled to the end wall of the cup (80).

11. 10. The actuator (100) of claims 3 and 9, wherein a portion of the first fluid circuit (61) traverses the lateral wall of the cup (80).

12. further comprising at least one seal (54); the seal (54) is located between the lateral wall (13) of the cylinder (10) and the lateral wall of the cup (80); The actuator (100) of claim 11, wherein the seal (54) is disposed about the first fluid circuit (61).

13. 2. The actuator (100, 200) of claim 1, further comprising a second fluid circuit (62) configured to supply fluid to the first variable volume chamber (35), the supplied fluid being configured to apply a fifth force to the first plate (30), the fifth force being opposite to the first force.

14. 1. A turboexpander system comprising: - a hydraulic or pneumatic actuator (100, 200) according to claim 1, a turboexpander machine (300) having a fluid inlet (301); a valve (400), in particular a trip valve, fluidly coupled to said fluid inlet (301) and configured to be actuated to stop said fluid supply to said fluid inlet (301); the valve (400) is mechanically coupled to the actuator (100, 200); A turboexpander system, wherein the test system (50) is configured to operate without actuating the valve (400).

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