JP2018021600A - Control valve for steam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control valve for steam capable of performing flow rate control with high accuracy in a low flow rate region in which a valve opening is small, and capable of having wide rangeability.SOLUTION: A control valve for steam includes: a valve body part including a valve seat 20 and a valve body 30; a controller for outputting a control signal of a valve opening; and a positioner for performing position control of the valve body according to the control signal. The valve seat includes: a valve body support part 25 for supporting the valve body by bringing it to contact at a valve port closing position of the valve body; and a cylindrical inflow part 23 having a cylindrical internal wall surface extending on the inflow side of steam along the advance/retreat direction of the valve body from the valve body support part. The valve body includes: a contact closing part coming into contact with the valve seat at the valve port closing position of the valve body; and a flow rate throttle part 37 extending in a tapered manner from a closing end on the cylindrical inflow part 23 side at the contact closing part. An outer peripheral surface of the flow rate throttle part of the valve body has a predetermined inclined angle with respect to the internal wall surface of the cylindrical inflow part of the valve seat.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a steam control valve that is attached to a piping system that circulates steam, has a closing function for closing the flow of steam, and can control the pressure and flow rate of secondary steam.

  In food, brewing, dairy, and chemical manufacturing processes, etc., multiple pipes (lines) that flow fluids such as liquid, gas, and steam are used, and multiple valves are arranged on these pipes. (Valve) adjusts the flow path, flow rate, pressure, etc. of the fluid. For example, when steam is used as a fluid, generally, high-pressure steam is generated by a boiler or the like, and the steam pressure is reduced by a pressure reducing valve provided on the line in accordance with the use of the steam. used.

  In addition, strict management is performed at the manufacturing site for food, pharmaceuticals, cosmetics, etc. to suppress contamination and generation of bacteria to improve the level of hygiene. For example, when steam is used, it is generated from pure water. Clean steam or pure steam generated from ultrapure water is used. In addition, the piping that distributes clean steam and pure steam is made of stainless steel that has been treated to be hygienic and polished so that it is difficult for dust and dirt to adhere to it, and it is easy to clean even if dust or dirt is attached. Sanitary piping is generally used.

  As the pressure reducing valve for reducing the steam pressure, a direct acting pressure reducing valve and a pilot pressure reducing valve are known, but the structure of the pressure reducing valve attached to the sanitary piping as described above is relatively simple. A direct-acting pressure reducing valve that is easy to disassemble, wash and assemble is used. On the other hand, a direct-acting pressure reducing valve has a narrow adjustable pressure range, a relatively large adjustable flow rate, a poor control accuracy at a small flow rate, and a secondary flow when flow fluctuation occurs on the primary side. The pressure on the side tends to fluctuate and there are drawbacks such as lack of stability.

  In order to make the steam pressure on the secondary side more stable than the pressure reducing valve, a control valve (control valve) may be used for the sanitary piping. The control valve has a controller that outputs a control signal for controlling the valve opening degree, and a positioner that controls the position of the valve body in accordance with the control signal of the controller. The valve opening degree can be controlled by performing position control. Further, for example, Japanese Patent Laid-Open No. 4-181082 (Patent Document 1) and International Publication No. 2014/007047 (Patent Document 2) disclose a control valve with a flow meter function having a controller and a positioner. Yes. In addition, in patent document 1 and patent document 2, it is not described in particular about using a control valve for sanitary piping.

Japanese Patent Laid-Open No. 4-181082 International Publication No. 2014/007047

  The control valve used for sanitary piping is required to be easy to disassemble and assemble in consideration of hygiene maintenance, and to withstand high temperatures and be difficult to break. The part (body) is formed with a relatively simple structure as shown in FIG. 7, for example.

  The valve body 71 of the control valve 70 shown in FIG. 7 is formed in an L shape. In this case, an inlet 72 for allowing fluid such as clean steam to flow into the valve main body 71 is provided at the lower end of the vertical pipe portion extending below the valve main body 71 so that the fluid flows out from the valve main body 71. An outflow port 73 is provided at the distal end portion of the horizontal pipe portion extending in the horizontal direction of the valve main body portion 71.

  A valve seat 74 and a valve body 75 that can be raised and lowered with respect to the valve seat 74 are provided inside the valve main body 71. Further, the height of the valve body 75 with respect to the valve seat 74 is controlled by a positioner (not shown), and the positioner controls the height position of the valve body 75 according to a setting signal input from a controller (not shown).

  The valve seat 74 is provided with a valve port 76 for circulating steam, and the valve port 76 is formed to have a circular shape in a plan view when the valve seat 74 is viewed from above. The valve seat 74 is arranged so as to be orthogonal to the ascending / descending direction of the valve body 75, and is chamfered from a valve seat upper surface portion 74a serving as a valve body receiving portion and an inner diameter side end portion of the valve seat upper surface portion 74a. The opening edge portion 74b extending in a curved shape and the cylindrical inflow portion 74c extending downward from the opening edge portion 74b in parallel with the advancing / retreating direction of the valve body 75 are provided.

  The valve body 75 is attached to an operating shaft 77 that can reciprocate in the vertical direction, and a diaphragm 78 is provided at the base end portion of the valve body 75. The outer peripheral end portion on the large diameter side of the diaphragm 78 is assembled in close contact with the housing portion 79 of the valve main body portion 71.

  The distal end portion of the valve body 75 includes a donut-shaped contact plane portion 75a that contacts the valve seat upper surface portion 74a of the valve seat 74 when the valve body 75 is held in the closed position, and a contact plane portion 75a. A non-contact flat surface portion 75b that extends inward to form a single flat surface with the contact flat surface portion 75a and does not contact the valve seat 74, and protrudes conically downward from an inner diameter side end of the non-contact flat surface portion 75b. And a projecting portion 75c.

  Since the non-contact flat surface portion 75b as described above is provided in the valve body 75, for example, when the valve body portion 71 is disassembled to be cleaned and then reassembled, the valve body 75 is set to the central axis of the valve seat 74. Even if the position of the central axis of the body 75 is slightly shifted, it is easy to ensure the sealing performance between the valve seat 74 and the valve body 75, and the assemblability (easiness of assembly) of the valve body 71 is improved.

  In the control valve 70 having the valve main body 71 as described above, the valve port 76 is closed by holding the valve body 75 in a position in contact with the valve seat 74 by a positioner (not shown) as shown in FIG. Thus, the flow of fluid such as clean steam can be stopped. Further, since the positioner can raise and lower the valve body 75 in accordance with a control signal input from the controller, for example, the valve body 75 is at different height positions as indicated by phantom lines in FIG. By being held, a gap corresponding to the height position of the valve body 75 is formed between the valve seat 74 and the valve body 75.

  Thereby, since the steam supplied from the primary side of the regulating valve 70 can flow out to the secondary side at a flow rate corresponding to the size of the gap formed between the valve seat 74 and the valve body 75, By controlling the size of the gap, the steam pressure on the secondary side can be adjusted.

  In particular, in the control valve 70 having the valve main body 71 as described above, the gap formed between the valve seat 74 and the valve body 75 increases as the height position of the valve body 75 with respect to the valve seat 74 increases. The height position of the valve body 75 controlled by the positioner is proportional to the size of the gap through which the fluid flows.

  For example, in FIG. 8, when the stroke capable of moving the valve body 75 up and down is 6 mm, the valve body 75 is fully opened when the valve body 75 is lifted 6 mm from the valve seat 74. Becomes 100%. Further, the valve opening degree when the valve body 75 is held at a position raised by 1 mm from the valve seat 74 is 16.7%, which is 1/6 of 100%. Therefore, when controlling the pressure on the secondary side of the control valve 70, the height position of the valve body 75 is appropriately adjusted by the controller and the positioner according to the magnitude of the set pressure.

  However, in the case of the regulating valve 70 having the valve main body 71 as described above, the gap (opening) formed between the valve seat 74 and the valve body 75 is enlarged in proportion to the height position of the valve body 75. In order to reduce, for example, in a low flow rate range where the valve opening is small, even if the height position of the valve body 75 changes slightly, the size of the gap between the valve seat 74 and the valve body 75 changes relatively greatly. The flow rate of fluid (clean steam, etc.) flowing through fluctuates greatly. As a result, it is difficult to control the pressure on the secondary side of the control valve 70 with high accuracy in the low flow rate range, and there is a drawback in that the controllability in the low flow rate range is not good.

  Furthermore, in this case, the minimum Cv value that can be controlled by the control valve 70 increases, and the range ability that serves as an index of the control range of the control valve 70 tends to decrease. Therefore, in the control valve arranged in the sanitary piping, it is required to increase the controllability of the control valve by ensuring a wider range ability without increasing the stroke of the valve body.

  The present invention has been made in view of the above-described conventional problems, and a specific object of the present invention is to perform flow control with high accuracy in a low flow range where the valve opening is small and to have a wide range ability. It is an object of the present invention to provide a steam control valve that can have the following.

  In order to achieve the above object, a steam control valve provided by the present invention opens and closes a valve seat provided with a valve port through which steam circulates, and opens and closes the valve port by separating and contacting the valve port. A valve body having a valve body; a controller that outputs a control signal for the valve opening of the valve body; and a positioner that controls the position of the valve body in accordance with the control signal of the controller. In the steam control valve, the valve seat is configured to contact and support the valve body at a valve port closed position of the valve body, and a forward and backward direction of the valve body from the valve body support part A cylindrical inflow portion having a cylindrical inner wall surface extending to the inflow side of the steam along the valve body, and the valve body includes the valve body support portion of the valve seat at the valve opening closed position of the valve body. A contact closure for contacting and stopping the flow of the steam; A flow restrictor extending in a tapered shape from a closed end on the cylindrical inflow portion side, and an outer peripheral surface of the flow restrictor of the valve body is configured with respect to an inner wall surface of the cylindrical inflow portion of the valve seat. The shortest distance between the flow restrictor and the valve seat of the valve body is the separation distance in the advancing and retreating direction of the valve body where the contact closing part of the valve body is separated from the valve body support part of the valve seat. The most important feature is that they are arranged with a predetermined inclination angle that is smaller than that.

  In such a steam control valve of the present invention, the outer peripheral surface of the flow restrictor is arranged so as to be linear in a cross-sectional view of the flow restrictor, and the flow rate with respect to the inner wall surface of the cylindrical inflow portion. It is preferable that the inclination angle of the outer peripheral surface of the throttle portion is set to 2 ° or more and 5 ° or less.

  Further, the valve body further includes a valve body distal end portion that further extends from the flow restrictor and has an outer peripheral surface having a larger inclination angle than the flow restrictor with respect to the cylindrical inflow portion of the valve seat, The flow restrictor of the valve body is preferably arranged from the closed end of the contact closing part to a position where the valve opening is 30% or more and 60% or less.

In the steam control valve of the present invention, it is preferable that the valve main body has a structure that can be disassembled and assembled, and the surface of the valve body is formed of a fluororesin.
In addition, a sensor unit that measures at least one of pressure, temperature, and flow rate on the secondary side of the steam is arranged, and the controller includes an input signal input from the sensor unit, a preset setting value, It is preferable to control the valve opening by comparing the above.
Further, it is preferably formed for pure steam or clean steam for distributing pure steam or clean steam in the valve body.

  The steam control valve according to the present invention includes a valve body having a valve seat and a valve body, a controller for outputting a control signal for valve opening, and position control of the valve body in accordance with the control signal of the controller. A positioner to perform. In addition, the valve seat of the valve body includes a valve body support portion that supports the valve body in contact with the valve body at a closed position of the valve body, and a steam inflow side from the valve body support portion along the advancing and retreating direction of the valve body. And a cylindrical inflow portion having a cylindrical inner wall surface extending in a straight line. The valve body of the valve body includes a contact closing portion that stops the flow of steam by contacting the valve body support portion of the valve seat at the valve opening closing position of the valve body, and a closed end on the cylindrical inflow portion side in the contact closing portion And a flow restrictor extending in a tapered shape.

  Furthermore, the outer peripheral surface of the flow restrictor of the valve body in the present invention is the shortest distance between the flow restrictor of the valve body and the valve seat with respect to the inner wall surface of the cylindrical inflow part of the valve seat, and the contact closing part of the valve body Is arranged so as to form a predetermined inclination angle that is smaller than the separation distance in the advancing and retreating direction of the valve body separated from the valve body support portion of the valve seat.

  In the case of the steam control valve of the present invention having such a structure, the valve body is formed from the valve opening closed position even though the valve body of the control valve is formed with a simple structure suitable for sanitary piping. When the valve body moves up to a predetermined height position, the distance between the valve body support part of the valve seat and the contact closing part of the valve body in the forward / backward direction of the valve body increases proportionally according to the height position of the valve body. However, the shortest distance between the flow restrictor of the valve body and the valve seat can be surely made smaller (narrower) than the separation distance.

  As a result, in a low flow rate range where the flow rate of fluid is small, a gap through which steam between the valve body and the valve seat can flow with respect to changes in the height position of the valve body (in other words, changes in the valve opening). The rate of change in size can be reduced. Therefore, for example, without using an expensive positioner with high position control resolution, the flow rate of steam can be controlled by finely changing the shortest distance between the flow restrictor of the valve body and the valve seat.

  For this reason, by adopting the valve main body of the present invention, it becomes possible to perform the flow control of steam more precisely and accurately than before without changing the controller and the positioner to expensive ones. Can be effectively improved, particularly in the low flow rate range.

  In particular, as described above, the minimum Cv value that can be controlled by the control valve is lower than that of the conventional control valve by controlling the minimum distance between the flow restrictor of the valve body and the valve seat more finely in the low flow range. It can be significantly reduced. Accordingly, the rangeability of the control valve can be ensured more widely than before without increasing the stroke of the valve body.

  In such a steam control valve of the present invention, the outer peripheral surface of the flow restrictor is arranged so as to be linear in a cross-sectional view of the flow restrictor, and the flow restrictor with respect to the inner wall surface of the cylindrical inflow portion. The inclination angle of the outer peripheral surface of the part is preferably set to 2 ° or more and 5 ° or less. As a result, the shortest distance between the flow restrictor of the valve body and the valve seat is surely made smaller than the separation distance in the forward and backward direction of the valve body between the valve body support part of the valve seat and the contact closing part of the valve body. Thus, the controllability in the low flow rate range of the control valve can be stably improved.

  In addition, the valve body of the present invention further includes a valve body distal end portion that further extends from the flow restricting portion and has an outer peripheral surface having a larger inclination angle than the flow restricting portion with respect to the cylindrical inflow portion of the valve seat. The flow restrictor is arranged from the closed end of the contact closing part to a position where the valve opening is 30% or more and 60% or less. As a result, the shortest distance between the flow restrictor of the valve body and the valve seat can be finely changed up to a range where the valve opening is at least 30%, so that the steam flow control is performed with high accuracy. Can do.

  Further, in the range where the valve opening is larger than 60%, the above-mentioned valve body tip is provided, so that the steam between the valve body and the valve seat with respect to the change in the height position of the valve body. It is possible to increase the rate of change in the size of the gap that can be circulated. As a result, the maximum Cv value that can be controlled by the control valve can be easily increased, so that a wide range ability can be stably secured.

  In the steam control valve of the present invention, the valve body has a simple structure that can be disassembled and assembled, and the surface of the valve body is made of a fluororesin. Thereby, since the valve main-body part of a control valve can be disassembled and wash | cleaned, it can be used conveniently for sanitary piping. In addition, because the surface of the valve body is made of fluororesin, the valve body can be easily slid with respect to the valve seat when it is assembled after disassembling the valve body. As a result, the valve body can be assembled. Thereby, the ease of assembly of the valve body can be improved, and the valve body and the valve seat can be prevented from being rubbed against each other and damaged.

  The control valve of the present invention is provided with a sensor unit that measures at least one of pressure, temperature, and flow rate on the secondary side of the steam, and the controller includes an input signal input from the sensor unit, The valve opening degree can be controlled by comparing with a preset value. By measuring the pressure on the secondary side and feeding it back to the controller in this way, the secondary pressure and the like can be stably and automatically controlled to a desired magnitude, and the secondary side pressure and the like can be controlled. It can respond to changes stably.

  The steam control valve of the present invention as described above is particularly preferably used as a control valve for pure steam or clean steam in which pure steam or clean steam is distributed in the valve body.

It is a schematic block diagram which shows the structure of the control valve for steam which concerns on embodiment of this invention. It is a fragmentary sectional view which expands and shows the valve main-body part of the control valve for steam typically. It is principal part sectional drawing which expands and shows the state in which the valve body of a valve main-body part is hold | maintained in the lowest position which contacts a valve seat, and a valve opening degree is 0%. It is explanatory drawing explaining the state which hold | maintained the circular part shown in FIG. 3 further expanding, and hold | maintained the valve body by raising 1 mm and 2 mm from the valve seat. It is explanatory drawing explaining the state which hold | maintained the valve body in a different height position for every 1 mm while showing the state whose valve opening is 100%. It is a graph which compares the flow volume characteristic of the steam control valve which concerns on embodiment, and the flow volume characteristic of the conventional steam control valve. It is a fragmentary sectional view which expands and shows the valve body part of the conventional control valve for steam typically. It is explanatory drawing explaining the state which hold | maintained the valve body in the different height position while the valve body of the conventional valve main-body part contacts a valve seat and shows the state of 0% of a valve opening degree.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below, and various modifications can be made as long as it has substantially the same configuration as the present invention and has the same effects. Is possible.
For example, in the present invention, the specific configurations of the controller and the positioner are not particularly limited, and various types that are currently commonly used can be used.

Here, FIG. 1 is a schematic configuration diagram showing the configuration of the steam control valve according to the present embodiment, and FIG. 2 is a partial cross-sectional view schematically showing the valve main body of the steam control valve. is there.
The steam control valve 1 of the present embodiment is formed as a pure steam or clean steam control valve 1 arranged in a sanitary pipe for circulating pure steam or clean steam as a fluid, and is a secondary downstream of the control valve 1. It is provided in order to control the pressure of the side pipe 7 to a predetermined constant magnitude.

  As shown in FIG. 1, the control valve 1 of the present embodiment is opened according to a valve main body (body) 10 including a valve seat 20 and a valve body 30 and the valve opening of the valve main body 10 to be set. A controller 2 that outputs a control signal of the degree, a positioner 3 that outputs air pressure to control the position of the valve body 30 in accordance with the control signal input from the controller 2, and air supplied from the positioner 3 The drive unit 4 that raises and lowers the valve body 30 relative to the valve seat 20 according to the pressure, and the positioner 3 that detects the actual valve opening degree by rotating around the base point according to the vertical movement of the valve body 30. A feedback lever 5 for feeding back to

  The valve body 10 circulates the steam flowing into the steam outlet 12 through the steam inlet 11 to which the primary side pipe 6 is connected, the steam outlet 12 to which the secondary side pipe 7 is connected, and the steam inlet 11. And a valve port 13 to be made. The valve port 13 is provided at a substantially central portion of the valve seat 20, and the valve port 13 is formed to have a circular shape when viewed from the upper side where the valve body 30 is inserted. The valve port 13 is opened and closed by the valve body 30 moving up and down with respect to the valve seat 20 to be separated and contacted.

  The controller 2 is electrically connected to a control unit (not shown) such as a PLC, for example. When information such as a desired valve opening degree or a secondary side steam pressure is set in the control unit, the setting information Based on this signal, the controller 2 inputs the controller 2. The controller 2 is connected to a pressure sensor unit 8 that measures the secondary side steam pressure, and the magnitude of the measured secondary side steam pressure is input from the pressure sensor unit 8 to the controller 2. The

  The controller 2 compares the set value (target value) input from the control unit with the actual value (output value) input from the pressure sensor unit 8, and performs PID control so that the actual value approaches the set value. Feedback control of the valve opening is performed and the control signal is output to the positioner 3. In this case, the controller 2 outputs an electric signal of 4 mA to 20 mA as a control signal for the valve opening. In the present invention, in addition to the pressure sensor unit 8 or in place of the pressure sensor unit 8, a temperature sensor unit that measures the secondary side steam temperature, a flow rate sensor unit that measures the secondary side steam flow rate, etc. It is also possible to feed back the measurement results to the controller 2.

  The positioner 3 of the present embodiment is formed as an electropneumatic positioner (electric / pneumatic valve positioner) 3. By converting an electric signal input from the controller 2 into a pneumatic signal and outputting it to the drive unit 4, Position control of the valve body 30 with respect to the valve seat 20 is performed.

  More specifically, the electropneumatic positioner 3 is supplied with a predetermined air pressure (compressed air) 3a from an air compressor (not shown) via a filter regulator (not shown), and an electric signal input from the controller 2 The air pressure is proportionally output with respect to (4 mA to 20 mA). The air pressure output from the electropneumatic positioner 3 is supplied to the cylinder part 4a of the drive part 4 through the synthetic resin pipe 3b.

  The drive unit 4 is connected to the valve body 30 and a cylinder 4 a to which air pressure is supplied from the electropneumatic positioner 3, a spring 4 b that is disposed below the piston of the cylinder 4 a and applies an upward biasing force. And an operating shaft 4c capable of reciprocating in the vertical direction. In this drive part 4, the operating shaft 4c is moved up and down by the action of the air pressure supplied to the cylinder part 4a and the urging force of the spring 4b, and the valve body 30 is moved up and down.

  That is, the drive part 4 can lower the valve body 30 via the operating shaft 4c by increasing the air pressure supplied from the electropneumatic positioner 3 to the cylinder part 4a. By reducing the air pressure, the valve body 30 can be raised through the operating shaft 4c. Accordingly, the drive unit 4 can raise and lower the valve body 30 in accordance with the magnitude of the air pressure supplied from the electropneumatic positioner 3, thereby changing the valve opening degree of the valve main body unit 10.

  The feedback lever 5 detects the amount of displacement of the operating shaft 4c by rotating around the base point according to the vertical movement of the operating shaft 4c, and the actual valve opening degree of the valve body 10 is determined based on the amount of displacement. Feedback is provided to the electropneumatic positioner 3. The electropneumatic positioner 3 corrects the air pressure supplied to the drive unit 4 when the actual valve opening to be fed back is different from the set valve opening, and sets the actual valve opening to a larger value. It can be adapted to the size.

Next, the valve main body 10 that is a main feature of the present embodiment will be described in more detail with reference to FIGS.
The valve body 10 of the present embodiment is formed in an L-shape, and includes a housing part 14 having a valve seat 20 and a valve body 30 therein, a vertical pipe part 15 suspended downward from the housing part 14, And a horizontal pipe portion 16 extending in the horizontal direction from the housing portion 14. A steam inlet 11 through which steam flows into the valve main body 10 is provided at the lower end of the vertical pipe section 15, and a steam flow through which steam flows out from the valve main body 10 at the tip of the horizontal pipe section 16. An outlet 12 is provided.

  In the valve body 10 of the present embodiment, the valve seat 20 is made of stainless steel. As shown in FIG. 3, the valve seat 20 includes a valve seat upper surface portion (valve body receiving portion) 21 having an upper surface orthogonal to the ascending / descending direction of the valve body 30, and an inner diameter side end of the valve seat upper surface portion 21. An opening edge portion (valve seat bending portion) 22 that extends in a curved shape in a cross-sectional view as if chamfered from the portion, and a cylindrical inflow portion 23 that extends downward from the opening edge portion 22 toward the steam inlet 11. In this case, the inner wall surface of the cylindrical inflow portion 23 is arranged in parallel with the advancing / retreating direction of the valve body 30 and is formed in a cylindrical shape.

  Further, the valve body 30 comes into contact with the valve body 30 in a state where the valve seat upper surface portion 21 and the opening edge portion 22 of the valve seat 20 are held at the valve port closed position where the valve body 30 closes the valve port 13. It becomes the valve body support part 25 which supports On the other hand, the cylindrical inflow portion 23 suspended from the opening edge portion 22 of the valve seat 20 becomes a valve body non-contact portion where the valve body 30 is separated in a state where the valve body 30 is held at the valve opening closed position. .

  In the valve seat 20 of the present embodiment, the valve seat upper surface portion 21 includes a flat upper surface orthogonal to the ascending / descending direction (advancing / retreating direction) of the valve body 30, but the upper surface of the valve seat upper surface portion 21 is The valve body 30 does not need to be disposed perpendicular to the ascending / descending direction. For example, the valve body 30 is disposed along a direction slightly inclined with respect to the direction orthogonal to the ascending / descending direction (substantially orthogonal direction). May be.

  In the present embodiment, an opening edge 22 having a curved surface in a sectional view is provided between the valve seat upper surface portion 21 and the cylindrical inflow portion 23. The curvature of the curved surface 22 is not particularly limited. Further, for example, the opening edge portion 22 is provided so that one or a plurality of bent portions are formed between the valve seat upper surface portion 21 and the cylindrical inflow portion 23 instead of exhibiting a curved surface if smooth. May be. In addition, the cylindrical inflow portion 23 of the valve seat 20 has an inner wall surface of the cylindrical inflow portion 23 that is substantially parallel to the advance / retreat direction of the valve body 30 with respect to the advance / retreat direction of the valve body 30. It may be formed so as to be slightly inclined.

  The valve body 30 (also referred to as a contour portion) is attached to the lower end portion of the operating shaft 4c of the drive unit 4 described above, and the height position with respect to the valve seat 20 is controlled by the electropneumatic positioner 3. In this embodiment, the stroke in the up-down direction of the valve body 30 is set to 6 mm. In this case, the valve opening when the valve body 30 is held at the lowermost position where it contacts the valve seat 20 is 0%, and the valve body 30 is raised 6 mm from the state where it is in contact with the valve seat 20. The valve opening when held is 100%.

  The valve body 30 of the present embodiment includes a stainless steel main body portion 31 attached to the operating shaft 4 c and a fluororesin surface portion 32 formed around the main body portion 31 so as to wrap the main body portion 31. Have. A substantially frustoconical diaphragm 33 is integrally formed at the upper end portion of the valve body 30 so as to be closely attached to the housing portion 14 of the valve main body portion 10 and ensure sealing performance. The diaphragm 33 includes a rubber backup rubber portion 33 a and a thin film portion 33 b that covers one surface of the backup rubber portion 33 a and is integrally formed with the surface portion 32 of the valve body 30.

  In this case, as the fluororesin that forms the surface portion 32 of the valve body 30 and the membrane portion 33b of the diaphragm 33, for example, tetrafluoroethylene resin (trade name: Teflon PTFE, fullon, etc.), tetrafluoroethylene and par Fluoroalkyl vinyl ether copolymer resin (trade name: Teflon PFA), terpolymer resin of tetrafluoroethylene, perfluoroalkyl vinyl ether and hexafluoropropylene (trade name: Teflon EPE), tetrafluoroethylene Copolymer resin of propylene hexafluoride (trade name: Teflon FEP), copolymer resin of ethylene tetrafluoride and ethylene (trade name: Teflon ETFE, Tefzel), polyvinylidene fluoride resin (trade name: Teflon PVDF, Kyner), a copolymer of trifluoromonochloroethylene and ethylene (trade name: Tefro) ECTFE), monofluoroethylene resin (trade name: it is possible to employ a Teflon PVF) and the like.

  The backup rubber portion 33a is made of silicon rubber (VMQ), nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), chloroprene rubber (CR), ethylene propylene rubber (EPDM), isoprene rubber, chloro Synthetic rubbers such as sulfonated rubber, styrene butadiene rubber, chlorinated polyethylene, acrylonitrile-butadiene copolymer rubber (NBR) can be employed.

  Further, the valve body 30 of the present embodiment extends from the inside of the valve body contact surface portion 35 and the valve body contact surface portion 35 that contacts the valve seat upper surface portion 21 of the valve seat 20 while being held at the valve opening closed position. The valve body bent portion 36 having a cross-sectional shape corresponding to the cross-sectional shape of the opening edge portion 22 of the valve seat 20, and the flow restrictor extending in a tapered shape (conical frustum shape) downward from the valve body bent portion 36. 37 and a valve body tip portion 38 that protrudes in a substantially conical shape from the lower end of the flow restrictor 37 through a bent portion.

  In the present embodiment, the valve body contact surface portion 35 and the valve body bent portion 36 of the valve body 30 are in contact with the valve seat 20 in a state where the valve body 30 is held at the valve opening closed position, as shown in FIG. Thus, a contact closing portion 39 for closing the valve port 13 is formed. Further, the flow restrictor 37 of the valve body 30 has an outer peripheral surface of the flow restrictor 37 with respect to an inner peripheral surface of the cylindrical inflow portion 23 of the valve seat 20 in a cross-sectional view. It is formed with an inclination angle α that is inclined obliquely linearly so as to gradually increase the gap between the closed end 39a on the cylindrical inflow portion 23 side and the cylindrical inflow portion 23.

  In this case, the inclination angle α at which the outer peripheral surface of the flow restrictor 37 is linearly inclined with respect to the inner peripheral surface of the cylindrical inflow portion 23 is set to 2 ° or more and 5 ° or less. When the inclination angle α is 2 ° or more, when the valve body 30 is slightly lifted from the valve closing position (for example, about 0.05 mm), the steam is smoothly smoothed between the valve body 30 and the valve seat 20. It is possible to stably form a gap that can be circulated. Further, the size of the gap formed between the flow restrictor 37 of the valve body 30 and the valve seat 20 can be appropriately changed corresponding to the height position of the valve body 30 with respect to the valve seat 20. It becomes possible to control the flow rate of steam stably with high accuracy.

  Further, when the inclination angle α is 5 ° or less, for example, the ascending distance of the valve body 30 (in other words, the valve body in which the contact closing portion 39 of the valve body 30 is separated from the valve body support portion 25 of the valve seat 20). 30), the shortest distance between the flow restrictor 37 of the valve body 30 and the valve seat 20 is reliably reduced, and the steam flowing between the valve body 30 and the valve seat 20 is reliably reduced. The flow rate can be effectively reduced. In particular, in the present embodiment, the inclination angle α of the outer peripheral surface of the flow restrictor 37 with respect to the inner peripheral surface of the cylindrical inflow portion 23 is preferably set to 2 °.

  Further, the flow restrictor 37 of the valve body 30 has a valve opening degree of 30% or more and 60% or less, preferably 40% or more and 55% from the closed end 39a of the contact closing part 39 of the valve body 30 on the cylindrical inflow portion 23 side. It is arranged to the following position. Particularly in the case of the present embodiment, the flow restrictor 37 of the valve body 30 is disposed from the closed end 39a to a position where the valve opening is 50%.

  Accordingly, the shortest distance between the flow restrictor 37 of the valve body 30 and the valve seat 20 is set in accordance with the height position of the valve body 30 controlled by the positioner 3 until the valve opening degree reaches 50%. By changing it finely, the flow rate control of the steam can be performed with high accuracy as will be described later. Furthermore, in the range where the valve opening is larger than 50%, the ratio of the change in the flow rate of steam with respect to the change in the height position of the valve body 30 can be increased. Can be bigger.

  On the other hand, the valve body tip portion 38 of the valve body 30 has an outer peripheral surface that is linearly inclined at an inclination angle of 50 ° or more and less than 90 ° with respect to the inner peripheral surface of the cylindrical inflow portion 23, and this embodiment Then, the inclination angle of the outer peripheral surface of the valve body tip portion 38 with respect to the inner peripheral surface of the cylindrical inflow portion 23 is set to 60 °. As a result, the valve body 30 is raised and the flow restrictor 37 of the valve body 30 is extracted from the cylindrical inflow portion 23 of the valve seat 20, so that the flow rate change of the steam with respect to the change in the height position of the valve body 30 is reduced. The ratio can be increased stably.

  Furthermore, the valve main body 10 in this embodiment disassembles the valve main body 10 by removing the metal dividing band 17 attached to the outside of the valve main body 10, so that the valve seat 20 and the diaphragm 33 are provided. The valve body 30 formed integrally can be detached and separated, and has a simple structure that can be restored to its original state by being reassembled and fixed with the divided band 17. Thereby, since the valve main-body part 10 can be wash | cleaned easily, the control valve 1 of this embodiment can be used suitably for the sanitary piping for which maintainability is calculated | required. Further, since the valve main body 10 is formed with a simple structure, the valve main body 10 is not easily broken even at high temperatures, and the cost of the control valve 1 can be reduced.

  Particularly in this case, since the surface portion 32 of the valve body 30 is formed of the fluororesin as described above, the valve body 30 can be easily attached to the valve seat 20 when the valve body portion 10 is assembled after being disassembled. The valve body 10 can be assembled by being stably attached to a predetermined position while sliding. Thereby, the ease of assembly of the valve main body 10 can be improved, and the valve body 30 and the valve seat 20 can be prevented from being rubbed against each other and damaged.

  In the control valve 1 of the present embodiment having the valve main body 10 as described above, the positioner 3 outputs a predetermined air pressure according to the control signal input from the controller 2, so that the valve body as described above. 30 position controls are performed. In this case, as shown in FIG. 2 to FIG. 4, the valve body 30 is held at the valve opening closed position in contact with the valve seat 20 by the positioner 3, thereby closing the valve opening 13 and distributing clean steam or the like. Can be stopped.

  Further, by changing the air pressure output from the positioner 3, the valve body 30 can be lifted from the valve opening closed position and held at the set required height position. At this time, in the valve main body 10 of the present embodiment, since the flow restrictor 37 is provided in the valve body 30, the valve body 30 is positioned at a predetermined height from the valve opening closed position, as will be described in detail below. (In the case of this embodiment, the flow rate of the steam passing between the valve body 30 and the valve seat 20 is reduced until the valve opening degree increases to 50%, and the height position of the valve body 30 is increased. The ratio of the flow rate change with respect to the change can be reduced.

  For example, in the case of the conventional control valve 70, as described with reference to FIGS. 7 and 8, when the stroke capable of raising and lowering the valve body 75 is 6 mm as in the present embodiment, the valve body 75 is When the valve is held at a position 6 mm above the seat 74, the valve opening is 100% (fully open). Further, when the valve body 75 is held at a position raised by 1 mm from the valve seat 74, the separation distance between the valve body 75 and the valve seat 74 in the forward / backward direction of the valve body 75 is 1 mm and the valve opening degree is 100. 16.7% which is 1/6 of%.

  On the other hand, in the case of this embodiment, as shown in FIGS. 2 to 4, the valve opening degree when the valve body 30 is held at the valve opening closed position is 0%. The surface portion 35 and the valve body bent portion 36 contact (closely contact) the valve seat upper surface portion 21 and the opening edge portion 22 of the valve seat 20, and steam flows between the valve body 30 and the valve seat 20. To prevent you from doing. As shown in FIG. 5, the valve opening when the valve body 30 is held at a position 6 mm above the valve seat 20 is 100% (fully open).

  4 and 5, the position of the valve body 30 when the valve body 30 is brought into contact with the valve seat 20 is indicated by a solid line or a reference virtual line L0, and the valve body 30 is different from the valve seat 20 by 1 mm. The position of the valve body 30 when held at the height position is indicated by a first imaginary line L1 to a fifth imaginary line L5 in order from the lowest height position. As shown in FIGS. 4 and 5, when the valve body 30 is held, for example, at a position raised by 1 mm from the valve seat 20 (first imaginary line L1 in FIGS. 4 and 5), the valve body of the valve body 30 Since the contact surface portion 35 rises from the valve seat upper surface portion 21 of the valve seat 20, the separation distance between them in the forward / backward direction of the valve body 30 is 1 mm as in the conventional case. On the other hand, the flow restrictor 37 of the valve body 30 is not greatly separated from the valve seat 20, and the shortest distance (minimum gap size) between the flow restrictor 37 of the valve element 30 and the valve seat 20 is set to It can be made extremely smaller than the rising distance (1 mm) of the body 30.

  For example, when the inclination angle α at which the outer peripheral surface of the flow restrictor 37 is inclined with respect to the inner peripheral surface of the cylindrical inflow portion 23 is set to 2 °, the valve body 30 is raised by 1 mm from the valve seat 20. When held, the shortest distance between the flow restrictor 37 of the valve body 30 and the valve seat 20 (the size of the smallest gap formed between them) D1 can be reduced to 0.06 mm. Further, when the valve body 30 is held at a position elevated by 2 mm from the valve seat 20 (second imaginary line L2 in FIGS. 4 and 5), the shortest distance between the flow restrictor 37 of the valve body 30 and the valve seat 20 is reached. The distance D2 can be set to 0.35 mm.

  As described above, in the present embodiment, since the flow restrictor 37 is provided in a predetermined range in the valve body 30, the change in the height position of the valve body 30 (valve until the valve opening degree reaches 50%) The rate of change of the shortest distance between the valve body 30 and the valve seat 20 (in other words, the rate of change of the steam flow rate) can be reduced. Particularly in this case, in the low flow rate range in which the valve opening is 30% or less, the shortest distance between the valve body 30 and the valve seat 20 with respect to the change in the height position of the valve body 30 (change in the valve opening). The rate of change (rate of change in steam flow) can be made very small.

  Thereby, even if the position control resolution of the positioner 3 is not so high, for example, the valve opening is within a range of 50% or less (particularly 30% or less) while the valve body 10 of the control valve 1 maintains a simple structure. The minimum distance between the flow restrictor 37 of the valve body 30 and the valve seat 20 can be controlled by changing more finely. As a result, it is possible to control the steam flow rate in the low flow rate region in the control valve 1 with finer and higher precision than before, and effectively improve the controllability of the secondary side steam pressure.

  FIG. 6 shows a graph comparing flow rate characteristics representing the relationship between the valve opening degree and the Cv value for the control valve 1 of the present embodiment and the conventional control valve 70 shown in FIGS. In FIG. 6, the solid line represents the flow characteristic of the control valve 1 of the present embodiment, and the two-dot chain line represents the flow characteristic of the conventional control valve 70.

  As shown in FIG. 6, in the control valve 1 of the present embodiment, the flow rate of steam flowing between the valve body 30 and the valve seat 20 can be reduced when the valve opening is in the range of 50% or less. The flow rate characteristic in the embodiment moves to the lower side than the flow rate characteristic of the conventional control valve 70, and the magnitude of the minimum Cv value that can be controlled by the control valve 1 can be made smaller than that of the conventional control valve. Actually, the minimum Cv value obtained with the conventional control valve 70 is 1.5, whereas the minimum Cv value obtained with the control valve 1 of the present embodiment is 0.4, which is half or less than the conventional value. Can be sized.

  On the other hand, in the control valve 1 of the present embodiment, the flow restrictor 37 of the valve body 30 is provided in a predetermined range, so that in a high flow range where the valve opening exceeds 60%, the change in the valve opening is not affected. The rate of change in the flow rate can be increased, whereby the maximum Cv value that can be controlled by the control valve 1 can be made substantially equal to that of the conventional control valve 70. Actually, the maximum Cv value obtained with the conventional control valve 70 is 15.0, whereas the maximum Cv value obtained with the control valve 1 of the present embodiment is 14.6.

  As a result, the range ability of the control valve 1 obtained by dividing the maximum Cv value by the minimum Cv value is 36.5 (= 14.6 / 0.4). Compared to 10 (15.0 / 1.5), in the control valve 1 of the present embodiment, the range ability can be greatly expanded as compared with the conventional case.

1 Control Valve 2 Controller 3 Positioner 3a Air Pressure (Compressed Air)
3b Synthetic resin pipe 4 Drive part 4a Cylinder part 4b Spring 4c Actuation shaft 5 Feedback lever 6 Primary side pipe 7 Secondary side pipe 8 Pressure sensor part 10 Valve body part (body)
DESCRIPTION OF SYMBOLS 11 Steam inflow port 12 Steam outflow port 13 Valve port 14 Housing part 15 Vertical pipe part 16 Horizontal pipe part 17 Dividing band 20 Valve seat 21 Valve seat upper surface part (Valve body receiving part)
22 Opening edge part 23 Cylindrical inflow part 25 Valve body support part 30 Valve body (contour part)
31 Main body part 32 Surface part 33 Diaphragm 33a Backup rubber part 33b Film part 35 Valve body contact surface part 36 Valve body bent part 37 Flow restrictor part 38 Valve body tip part 39 Contact closed part 39a Closed end D1, D2 Shortest distance L0 Reference virtual line L1 to L5 First imaginary line to fifth imaginary line α Inclination angle

Claims (6)

A valve seat (20) having a valve port (13) through which steam circulates, and a valve body (30) that opens and closes the valve port (13) by separating and contacting the valve port (13). A valve main body (10), a controller (2) that outputs a control signal of the valve opening of the valve main body (10), and the valve body (30) according to the control signal of the controller (2). A steam control valve (1) having a positioner (3) for controlling the position of
The valve seat (20) includes a valve body support section (25) that supports the valve body (30) by contacting the valve body (30) at a valve opening closed position of the valve body (30), and the valve body support section (25). A cylindrical inflow part (23) having a cylindrical inner wall surface extending from the inflow side of the steam along the advancing and retreating direction of the valve body (30),
The valve body (30) is in contact with the valve body support portion (25) of the valve seat (20) at the valve opening closed position of the valve body (30) to stop the flow of the steam. 39) and a flow restrictor (37) extending in a tapered shape from the closed end (39a) on the cylindrical inflow portion (23) side of the contact closing portion (39),
An outer peripheral surface of the flow restrictor (37) of the valve body (30) is an inner wall surface of the cylindrical inflow part (23) of the valve seat (20), and the flow restrictor of the valve body (30). The contact closing portion (39) of the valve body (30) is separated from the valve body support portion (25) of the valve seat (20) so that the shortest distance between the valve seat (20) and the valve seat (20) is The valve body (30) is arranged with a predetermined inclination angle (α) that is smaller than the separation distance in the advancing and retreating direction,
This is a steam control valve. The outer peripheral surface of the flow restrictor (37) is arranged so as to exhibit a linear shape in a sectional view of the flow restrictor (37),
The inclination angle (α) of the outer peripheral surface of the flow restrictor (37) with respect to the inner wall surface of the cylindrical inflow portion (23) is set to 2 ° or more and 5 ° or less.
The steam control valve according to claim 1. The valve body (30) further extends from the flow restrictor (37) and has a larger inclination angle than the flow restrictor (37) with respect to the cylindrical inflow portion (23) of the valve seat (20). It has a valve body tip (38) with an outer peripheral surface,
The flow restrictor (37) of the valve body (30) is arranged from the closed end (39a) of the contact closing part (39) to a position where the valve opening is 30% or more and 60% or less. Become,
The control valve for steam according to claim 1 or 2. The valve body (10) has a structure that can be disassembled and assembled,
The surface portion (32) of the valve body (30) is formed of a fluororesin,
The steam control valve according to any one of claims 1 to 3. A sensor unit (8) for measuring at least one of pressure, temperature, and flow rate on the secondary side of the steam;
The controller (2) controls the valve opening by comparing an input signal input from the sensor unit (8) with a preset value.
The steam control valve according to any one of claims 1 to 4.   The steam control valve according to any one of claims 1 to 5, wherein the steam control valve is formed for pure steam or clean steam in which pure steam or clean steam is distributed in the valve body (10).

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