JP2017091031A - Regulating valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a regulating valve capable of accurately computing a flow rate even if steal is overheated steam.SOLUTION: A regulating valve 100 is equipped with a valve body 10 which has a valve body 16; and a control portion 30 which adjusts a flow rate Q of steam circulating in the valve body 10 by controlling an opening of the valve body 10. The regulating valve 100 is further equipped with a first sensor 41 for detecting first pressure P1 which is pressure of steam on an upstream side of the valve body 16 and first temperature T1 which is temperature of the steam on the upstream side of the valve body 16, a second sensor 42 for detecting second pressure P2 which is pressure of steam on a downstream side of the valve body 16; and a memory 50 which stores Cv value characteristics which is a relationship between the opening of the valve body 10 and a Cv value. The control portion 30 computes a flow rate Q, on the basis of the Cv value corresponding to the opening of the valve body 10 obtained on the basis of the opening of the valve body 10 and the Cv value characteristics of the memory 50, the first pressure P1, the first temperature T1, and the second pressure P2.SELECTED DRAWING: Figure 1

Description

  The technology disclosed herein relates to a control valve.

  2. Description of the Related Art Conventionally, there is known a control valve that adjusts the flow rate of flowing steam and that can calculate the flow rate.

  For example, in the control valve described in Patent Literature 1, the upstream temperature and the downstream temperature of the valve are obtained, and these temperatures are converted into the upstream steam pressure and the downstream steam pressure, and these pressures are calculated. Is used to calculate the flow rate of steam.

Japanese Patent No. 5406417

  However, in the control valve described in Patent Document 1, the temperature of the steam is converted into a pressure using the relationship between the saturation temperature and the saturation vapor pressure. That is, the flow rate is calculated on the assumption that the steam is saturated steam. Therefore, when the steam is superheated steam, the calculation accuracy of the flow rate is lowered.

  The technology disclosed herein has been made in view of such points, and an object thereof is to provide a control valve capable of calculating the flow rate with high accuracy even when the steam is superheated steam.

  The technology disclosed herein is directed to a control valve including a valve body having a valve body, and a control unit that adjusts the flow rate of steam flowing through the valve body by controlling the opening of the valve body. To do. The regulating valve detects a first pressure that is a pressure of steam upstream of the valve body, and a temperature detector that detects a first temperature that is the temperature of steam upstream of the valve body. A second pressure detection unit that detects a second pressure that is a pressure of steam downstream of the valve body, and a storage unit that stores a Cv value characteristic that is a relationship between the degree of opening of the valve body and the Cv value; The control unit further includes a Cv value corresponding to the opening of the valve body, which is obtained based on the opening of the valve body and the Cv value characteristic of the storage unit, and the first pressure detection unit. The flow rate of the steam flowing through the valve body based on the first pressure detected by the temperature detection unit, the first temperature detected by the temperature detection unit, and the second pressure detected by the second pressure detection unit. Calculate.

  According to the control valve disclosed here, the flow rate can be accurately calculated even if the steam is superheated steam.

FIG. 1 is a schematic configuration diagram of a control valve. FIG. 2 is a flowchart showing the flow rate calculation process.

  Hereinafter, exemplary embodiments will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a control valve.

  The control valve 100 is an air-driven control valve, and has a flow meter function. The control valve 100 includes a valve body 10 having a valve body 16, a drive unit 20 that drives the valve body 10, a control unit 30 that controls the drive unit 20, and a steam pressure upstream of the valve body 16. A first sensor 41 that detects a first pressure P1 and a first temperature T1 that is the temperature of steam upstream of the valve body 16, and a second sensor that detects a second pressure P2 that is the pressure of steam downstream of the valve body 16. The sensor 42 includes a memory 50 that stores a Cv value characteristic that is a relationship between the opening degree of the valve body 10 and the Cv value.

  The valve body 10 includes a casing 11 having an inlet 12 and an outlet 13, a valve port 14, a valve seat 15 accommodated in the casing 11, a valve body 16 that opens and closes the valve port 14, and a valve body 16. And a stem 17 connected thereto.

  An upstream pipe 61 is connected to the inlet 12. A downstream pipe 62 is connected to the outlet 13. The inlet 12 and the outlet 13 communicate with each other through the valve port 14 in the casing 11. Steam from the upstream pipe 61 flows into the casing 11 through the inlet 12, and the steam that has passed through the valve port 14 flows out to the downstream pipe 62 through the outlet 13.

  The opening degree of the valve port 14 is adjusted by the valve body 16. The valve port 14 is closed when the valve body 16 is seated on the valve seat 15. As the valve body 16 moves away from the valve seat 15, the opening of the valve port 14 increases. The stem 17 is also connected to the drive unit 20. The valve body 16 is driven by the drive unit 20 via the stem 17.

  The drive unit 20 includes a casing 21, a diaphragm 22 that partitions the space in the casing 21 into an upper space 21 a and a lower space 21 b, a spring 23 that urges the diaphragm 22 upward, and a valve that adjusts the position of the valve body 16. And a positioner 24.

  Driving air is supplied to the valve positioner 24 via a supply pipe 25. The valve positioner 24 receives a command from the control unit 30, adjusts the pressure of the air supplied from the supply pipe 25 based on the command, and adjusts the pressure-adjusted air to the upper space 21 a of the casing 21 via the conduit 26. Supply. The diaphragm 22 is displaced up and down by the balance between the upper space 21 a and the biasing force of the spring 23. A stem 17 is connected to the diaphragm 22. When the diaphragm 22 is displaced up and down, the valve body 16 is displaced via the stem 17.

  The valve positioner 24 has a lever 27 connected to the stem 17. That is, the valve positioner 24 detects the displacement of the stem 17, that is, the displacement of the valve body 16 based on the displacement of the lever 27.

  The first sensor 41 is a sensor that detects both the pressure and temperature of the fluid. The first sensor 41 is attached to the inlet 12 of the casing 11. The first sensor 41 detects the pressure and temperature of the fluid passing through the inlet 12. The second sensor 42 is a sensor that detects the pressure of the fluid. The second sensor 42 is attached to the outlet 13 of the casing 11. The second sensor 42 detects the pressure of the fluid passing through the outlet 13. The first sensor 41 is an example of a first pressure detection unit and a temperature detection unit. The second sensor 42 is an example of a second pressure detection unit.

  The control unit 30 includes a processor and is connected to the memory 50 so as to be able to exchange signals. In addition, the first sensor 41 and the second sensor 42 are connected to the control unit 30, and detection signals of the first sensor 41 and the second sensor 42 are input. The control unit 30 outputs a command to the valve positioner 24 in order to set the opening degree of the valve body 10 to the target opening degree. That is, the control unit 30 outputs a command to the valve positioner 24 so that the position of the valve body 16 becomes a position corresponding to the target opening. In addition, the control unit 30 calculates the flow rate Q of the steam flowing through the valve body 10.

  The memory 50 stores in advance a Cv value characteristic that is a relationship between the opening degree of the valve body 10 and the Cv value, and a saturated vapor pressure characteristic that is a relationship between the saturation temperature of the steam and the saturated vapor pressure. The memory 50 is an example of a storage unit.

  Hereinafter, the calculation of the flow rate Q will be described with reference to the flowchart of FIG.

  In step S <b> 1, the control unit 30 reads the target opening of the valve body 10 corresponding to the command output to the valve positioner 24, and compares the target opening with the Cv value characteristic of the memory 50 to correspond to the target opening. Find the value.

  In step S <b> 2, the control unit 30 reads the first pressure P <b> 1 and the first temperature T <b> 1 that are detection results of the first sensor 41, and the second pressure P <b> 2 that is the detection result of the second sensor 42.

  Subsequently, in step S3, the control unit 30 determines whether or not the steam flowing through the valve body 10 is superheated steam. Specifically, the control unit 30 obtains a saturation temperature corresponding to the first pressure P1 by comparing the first pressure P1 with the saturated vapor pressure characteristic of the memory 50, and whether or not the first temperature T1 is higher than the saturation temperature. Determine whether. When the first temperature T1 is higher than the saturation temperature, the control unit 30 determines that the steam is superheated steam. On the other hand, when the first temperature T1 is equal to or lower than the saturation temperature, the control unit 30 Is determined not to be superheated steam.

  When the steam is superheated steam, the control unit 30 calculates the superheat degree S (= first temperature T1−saturation temperature) in step S4. On the other hand, when the steam is not superheated steam, the control unit 30 sets the superheat degree S = 0 in step S5.

  Subsequently, in step S6, the control unit 30 determines the Cv value, the first pressure P1 [MPa (abs)], the first temperature T1 [° C], the second pressure P2 [MPa (abs)], and the superheat S [° C]. ] To calculate the flow rate Q [kg / h] based on the following equation (1). Note that ΔP = P1−P2.

ただし、第２圧力Ｐ２がＰ１／２よりも小さいときには、制御部３０は、以下の式（２）に基づいて流量Ｑ［ｋｇ／ｈ］を算出す

However, when the second pressure P2 is smaller than P1 / 2, the control unit 30 calculates the flow rate Q [kg / h] based on the following equation (2).

式（１）、（２）によれば、過熱度Ｓを考慮して流量Ｑが算出されるので、蒸気が過熱蒸気の場合であっても、流量Ｑを精度良く演算することができる。一方、蒸気が過熱蒸気でない場合には、過熱度Ｓ＝０とすることによって流量Ｑを精度良く演算することができる。

According to the equations (1) and (2), the flow rate Q is calculated in consideration of the degree of superheat S, so that the flow rate Q can be calculated with high accuracy even when the steam is superheated steam. On the other hand, when the steam is not superheated steam, the flow rate Q can be accurately calculated by setting the superheat degree S = 0.

  As described above, the adjustment valve 100 includes the valve body 10 having the valve body 16 and the control unit 30 that adjusts the flow rate of the steam flowing through the valve body 10 by controlling the opening degree of the valve body 10. Yes. The control valve 100 includes a first sensor 41 (first pressure detection) that detects a first pressure P1 that is the pressure of steam upstream of the valve body 16 and a first temperature T1 that is the temperature of steam upstream of the valve body 16. Part, temperature detection part), a second sensor 42 (second pressure detection part) for detecting the second pressure P2, which is the pressure of steam downstream of the valve body 16, and the opening degree and Cv value of the valve body 10. The memory 50 (storage unit) that stores the Cv value characteristic that is a relationship of the valve body 10, and the control unit 30 of the valve body 10 that is obtained based on the opening degree of the valve body 10 and the Cv value characteristic of the memory 50. The Cv value corresponding to the opening, the first pressure P1 detected by the first sensor 41, the first temperature T1 detected by the first sensor 41, and the second pressure P2 detected by the second sensor 42 Based on the above, the flow rate Q of the steam flowing through the valve body 10 is calculated.

  According to this configuration, not only the upstream and downstream steam pressures of the valve body 16 (first pressure P1 and second pressure P2), but also the upstream steam temperature of the valve body 16 (first temperature T1). The flow rate Q is determined in consideration of the above. Therefore, even if the steam is superheated steam, the flow rate Q can be obtained with high accuracy.

  Specifically, the control unit 30 determines whether or not the steam is superheated steam based on the first pressure P1 and the first temperature T1, and when the steam is superheated steam, considers the superheat degree S and controls the valve. The flow rate Q of the steam flowing through the main body 10 is calculated.

  According to this configuration, it is possible to determine whether or not the steam is superheated steam, and when the steam is superheated steam, the flow rate Q is obtained in consideration of the superheat degree S.

  Further, the first sensor 41 detects the first pressure P1 and the first temperature T1 at the same position in the steam flow path.

  According to this configuration, it is possible to improve the accuracy of determining whether the steam is superheated steam and the accuracy of calculating the superheat degree.

<< Other Embodiments >>
As described above, the embodiment has been described as an example of the technique disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can also be applied to an embodiment in which changes, replacements, additions, omissions, and the like are appropriately performed. Moreover, it is also possible to combine each component demonstrated by the said embodiment and it can also be set as a new embodiment. In addition, among the components described in the attached drawings and detailed description, not only the components essential for solving the problem, but also the components not essential for solving the problem in order to illustrate the technology. May also be included. Therefore, it should not be immediately recognized that these non-essential components are essential as those non-essential components are described in the accompanying drawings and detailed description.

  About the said embodiment, it is good also as following structures.

  The configuration of the control valve 10 is merely an example and is not limited to this. For example, the opening degree of the valve port 14 may be configured to be adjusted by means other than the valve positioner 24.

  The first sensor 41 is a sensor that detects both the first pressure P1 and the first temperature T1, but a sensor that detects the first pressure P1 and a sensor that detects the first temperature T1 may be provided separately. Good. In that case, the sensor for detecting the first pressure P1 and the sensor for detecting the first temperature T1 may be provided at different positions in the steam flow path.

  The first sensor 41 and the second sensor 42 are provided in the casing 11 (specifically, the inlet 12 and the outlet 13), but may be provided in the upstream side pipe 61 and the downstream side pipe 62, respectively.

  The first sensor 41 directly detects the temperature of the steam, but may detect the temperature of the steam indirectly by detecting the surface temperature of the casing 11 or the surface temperature of the upstream pipe 61. Good.

  The flowchart shown in FIG. 2 is merely an example, and as long as the flow rate Q can be obtained, the order of the steps may be changed or the steps may be omitted. For example, the order of step S1 and step S2 may be interchanged, or both may be processed in parallel.

  As described above, the technique disclosed herein is useful for a control valve.

DESCRIPTION OF SYMBOLS 100 Control valve 10 Valve main body 16 Valve body 30 Control part 41 1st sensor (1st pressure detection part, temperature detection part)
42 2nd sensor (2nd pressure detection part)
50 memory (storage unit)

Claims (3)

A valve body having a valve body;
A control valve comprising a control unit for adjusting a flow rate of steam flowing through the valve body by controlling an opening degree of the valve body,
A first pressure detector that detects a first pressure that is a pressure of steam upstream of the valve body;
A temperature detector that detects a first temperature that is the temperature of the steam upstream of the valve body;
A second pressure detection unit that detects a second pressure that is a pressure of steam downstream of the valve body;
A storage unit storing a Cv value characteristic that is a relationship between the opening of the valve body and the Cv value;
The control unit is detected by the first pressure detection unit and a Cv value corresponding to the opening of the valve body, which is obtained based on the opening of the valve body and the Cv value characteristic of the storage unit. Based on the first pressure, the first temperature detected by the temperature detector, and the second pressure detected by the second pressure detector, calculating the flow rate of the steam flowing through the valve body. Characteristic regulating valve. The control valve according to claim 1,
The controller determines whether the steam is superheated steam based on the first pressure and the first temperature, and when the steam is superheated steam, the steam flowing through the valve body in consideration of the degree of superheat. A control valve characterized by calculating the flow rate of the valve. The control valve according to claim 1 or 2,
The temperature detecting unit detects the first temperature at the same position as the first pressure detecting unit in the steam flow path.

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