JP2014126425A - Flow rate calculation device and flow rate control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow rate calculation device and a flow rate control device capable of performing accurate flow rate control even when a cavitation flow is dominant in the flow of the liquid passing through a regulating valve.SOLUTION: When a determination part 20 determines that a cavitation flow is dominant in the flow of the liquid passing through a regulating valve 2, a flow calculation part 23 derives a flow rate coefficient Cv based on a second table which stores a pressure ratio XF and an opening degree θ in association with the flow rate coefficient Cv in a state that the cavitation flow is dominant. In this manner, a flow rate Q of the fluid flowing through the regulating value 2 is calculated using the derived flow rate coefficient Cv. Thereby, even when the cavitation flow is dominant, the flow rate Q can be accurately calculated, and as a result, more accurate flow rate control can be performed than before.

Description

  The present invention relates to a flow rate calculation device that calculates the flow rate of fluid that passes through a control valve, and a flow rate control device that includes this flow rate calculation device.

  Conventionally, the flow rate of a fluid flowing through a pipe of a plant or the like is controlled by a control valve provided in the pipe. Specifically, the flow rate Q passing through the control valve is calculated by the following equation (1), and the opening degree of the control valve is controlled so that the flow rate Q matches the set flow rate Qsp. A fluid with a flow rate is allowed to pass (see, for example, Patent Document 1). Here, ΔP is the differential pressure (P1−P2) between the pressure P1 in the primary (upstream) flow path of the control valve and the pressure P2 in the secondary (downstream) flow path, and Cv is the flow coefficient. And is set for each valve opening θ of the control valve.

Q = A · Cv · ΔP ^1/2 (1)

  Among these, the flow coefficient Cv of the control valve varies depending on the diameter and type of the control valve, and therefore it is necessary to obtain an appropriate value in accordance with the target control valve. Therefore, for example, a plurality of differential pressures such as every several Pa are set in advance, and the flow coefficient Cv corresponding to each opening when the opening of the control valve is changed every predetermined value such as every several% for each of these differential pressures. A table in which this value is associated with the differential pressure and each opening degree is stored in a memory such as a control valve actuator or a flow rate measuring device at the time of shipment. When measuring the actual flow rate, a corresponding Cv value is derived based on the table, the measured differential pressure, and the actual opening of the control valve, and is substituted into the above equation (1). The flow rate Q is acquired, and the opening degree of the control valve is controlled so that the flow rate Q matches the set flow rate Qsp.

JP-A-6-094160

  However, since the flow coefficient table described above is based on the premise that cavitation does not occur in the control valve, when the cavitation occurs in the control valve and the cavitation flow becomes dominant, each Cv value in the flow coefficient Cv value table. No longer corresponds to the actual value. Then, the flow rate Q obtained using the above equation (1) is not an actual flow rate, and as a result, accurate flow rate control cannot be performed.

  Accordingly, an object of the present invention is to provide a flow rate calculation device and a flow rate control device that can perform accurate flow rate control even when the cavitation flow is dominant.

  In order to solve the problems as described above, a flow rate calculation device according to the present invention includes a first pressure, which is a pressure of a fluid flowing upstream from a throttle portion of a control valve connected to a flow path, An acquisition unit for acquiring at least two of the second pressure, which is the pressure of the fluid flowing downstream from the throttle unit, and the differential pressure between the first pressure and the second pressure; Based on at least two of the first pressure, the second pressure, and the differential pressure acquired by the acquisition unit, and a valve opening degree acquisition unit that acquires the degree, the first pressure, the first pressure, and the second pressure A coefficient calculation unit for calculating a first coefficient based on a pressure difference between the first pressure and the saturated vapor pressure of the fluid; and a first pressure in a state where the cavitation flow is not dominant in the flow of the fluid passing through the control valve; The second differential pressure and valve opening are associated with the flow coefficient. A first table in which the cavitation flow is dominant in the flow of fluid passing through the control valve, and the second table storing the first coefficient, the valve opening degree, and the flow coefficient in association with each other. A determination unit that determines whether the cavitation flow is dominant in the flow of fluid passing through the control valve, and the determination unit determines that the cavitation flow is not dominant in the flow of fluid that passes through the control valve In this case, a flow coefficient is derived based on the differential pressure, the valve opening degree, and the first table, the flow rate of the fluid flowing through the control valve is calculated based on the flow coefficient and the differential pressure, and the control valve is operated by the determination unit. When it is determined that cavitation is dominant in the flow of fluid passing therethrough, a flow coefficient is derived based on the first coefficient, the valve opening degree, and the second table. It is characterized in further comprising a flow rate computation unit for computing the flow rate of the fluid flowing through the regulating valve on the basis of the amount coefficient and the differential pressure.

  In the above-described flow rate calculation device, the coefficient calculation unit calculates the first coefficient from XF = ΔP / (P1−PV), where XF is the first coefficient, ΔP is the differential pressure, P1 is the first pressure, and PV is the saturated vapor pressure. A coefficient of 1 may be calculated.

  The flow rate calculation device further includes a storage unit that stores a threshold value set according to the valve opening, and the determination unit is stored in the storage unit with the first coefficient calculated by the coefficient calculation unit. The cavitation flow may be determined to be dominant in the flow of fluid passing through the control valve when the first coefficient is equal to or greater than the threshold value.

  The flow rate calculation device further includes a temperature acquisition unit that acquires the temperature of the fluid flowing through the flow path, and a third table that stores a saturated vapor pressure for each temperature of the fluid, and the coefficient calculation unit includes the temperature acquisition unit. The first coefficient may be calculated using the saturated vapor pressure derived based on the temperature of the fluid acquired by the unit and the third table.

  The flow rate control device according to the present invention includes a flow rate calculation device that calculates the flow rate of the fluid flowing through the control valve connected to the flow path, and the control valve so that the flow rate calculated by the flow rate calculation device matches a set value. The flow rate control device includes a valve control device that controls the degree of opening, and the flow rate calculation device includes the above-described flow rate calculation device.

  According to the present invention, when it is determined that the cavitation flow is not dominant in the flow of fluid passing through the control valve, the first state in the state where the cavitation flow is not dominant in the flow of fluid passing through the control valve. When the flow coefficient is derived based on the first table in which the differential pressure between the pressure and the second pressure, the valve opening, and the flow coefficient are stored in association with each other, and it is determined that the cavitation flow is dominant, The flow coefficient is derived based on the second table in which the first coefficient, the valve opening degree, and the flow coefficient are stored in association with each other in a state where the cavitation flow is dominant in the flow of the fluid passing through the control valve. Because the flow rate of fluid flowing through the control valve is calculated using the flow coefficient derived in this way, accurate flow control even when the cavitation flow is dominant It can be carried out.

FIG. 1 is a diagram schematically showing a configuration of a flow control system according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the flow rate calculation device. FIG. 3 is a diagram for explaining the configuration of the first table. FIG. 4 is a diagram for explaining the configuration of the second table. FIG. 5 is a block diagram showing the configuration of the valve control device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Configuration of flow control system]
As shown in FIG. 1, the flow rate control system according to the present embodiment includes a flow path 1, a control valve 2 provided in the flow path 1, a temperature sensor 3 provided in the flow path 1, and a control valve. The primary pressure sensor 4 provided on the upstream side (primary side) of the throttle part in 2 and the secondary pressure sensor 5 provided on the downstream side (secondary side) of the throttle part in the control valve 2. And a valve opening sensor 6 provided in the control valve 2 and a flow rate control unit 7 for controlling the flow rate of the fluid flowing through the flow path 1.

  The flow path 1 consists of one piping provided in a plant etc., and a fluid distribute | circulates the inside.

  The control valve 2 has a flow path inside, a valve body having a throttle portion in the middle of the flow path, and a valve body that is disposed inside the valve main body and regulates the flow rate of fluid passing through the throttle portion, The valve body is composed of a flow control unit 7 such as an electric actuator or a positioner that controls the opening degree by driving the valve body. By changing the valve opening degree based on a control signal from the flow control unit 7, the control valve 2 is controlled. The flow rate of the fluid passing therethrough, that is, the flow rate of the fluid flowing in the flow path 1 is controlled.

  The temperature sensor 3 is a known temperature sensor and measures the temperature T of the fluid flowing in the flow path 1. This measurement result is transmitted to the flow control unit 7.

  The primary pressure sensor 4 is a known pressure sensor, and measures the pressure P1 of the fluid flowing in the flow path upstream (primary side) from the throttle portion in the control valve 2. This measurement result is transmitted to the flow control unit 7.

  The secondary pressure sensor 5 is a known pressure sensor, and measures the pressure P2 of the fluid flowing in the flow path on the downstream side (secondary side) of the throttle portion in the control valve 2. This measurement result is transmitted to the flow control unit 7.

  The valve opening sensor 6 is a sensor that measures the valve opening θ of the control valve 2. This measurement result is transmitted to the flow control unit 7.

<Configuration of flow control unit>
The flow rate control unit 7 calculates the flow rate of the fluid flowing through the flow path 1 based on the measurement results received from the temperature sensor 3, the primary side pressure sensor 4, the secondary side pressure sensor 5, and the valve opening degree sensor 6. 8 and a valve control device 9 that controls the valve opening degree of the control valve 2 by generating a control signal based on the calculation result of the flow rate calculation device 8 and transmitting the control signal to the control valve 2.

≪Configuration of flow rate calculation device≫
Here, as shown in FIG. 2, the flow rate calculation device 8 includes a temperature acquisition unit 11, a primary pressure acquisition unit 12, a secondary pressure acquisition unit 13, a third table 14, and a saturated vapor pressure derivation unit 15. A differential pressure calculation unit 16, a coefficient calculation unit 17, a valve opening degree acquisition unit 18, a threshold storage unit 19, a determination unit 20, a first table 21, a second table 22, and a flow rate calculation. Part 23.

  The temperature acquisition unit 11 is a functional unit that acquires the temperature T of the fluid flowing through the flow path 1 measured by the temperature sensor 3 from the temperature sensor 3. The acquired temperature T is output to the saturated vapor pressure deriving unit 15.

  The third table 14 includes a data table that stores the temperature T of the fluid and the saturated vapor pressure PV in association with each other. As an example, the third table 14 stores a temperature T1 set in increments of a predetermined value such as every 0.1 ° C. and a saturated vapor pressure PV corresponding to each temperature T1 in association with each other.

  The saturated vapor pressure deriving unit 15 calculates the saturated vapor pressure PV of the fluid flowing through the flow channel 1 based on the temperature T1 of the fluid flowing through the flow channel 1 input from the temperature acquisition unit 11 and the third table 14. To derive. Specifically, the saturated vapor pressure PV corresponding to the temperature T input from the temperature acquisition unit 11 is derived with reference to the third table 14. The derived saturated vapor pressure PV is output to the coefficient calculation unit 17. Thus, since the saturated vapor pressure PV corresponding to the fluid temperature T is derived, the calculation accuracy of the pressure ratio XF by the coefficient calculation unit 17 described later is improved.

  The primary pressure acquisition unit 12 is a functional unit that acquires, from the primary side pressure sensor 4, the pressure P <b> 1 of the fluid flowing through the primary side flow path measured by the primary side pressure sensor 4. The acquired pressure P1 is output to the differential pressure calculation unit 16 and the coefficient calculation unit 17.

  The secondary pressure acquisition unit 13 is a functional unit that acquires, from the secondary side pressure sensor 5, the pressure P <b> 2 of the fluid flowing through the secondary side flow path measured by the secondary side pressure sensor 5. The acquired pressure P2 is output to the differential pressure calculation unit 16 and the coefficient calculation unit 17.

  The differential pressure calculation unit 16 is a functional unit that calculates a differential pressure ΔP (= P1−P2) between the pressure P1 input from the primary pressure acquisition unit 12 and the pressure P1 input from the secondary pressure acquisition unit 13. . The obtained differential pressure ΔP is output to the coefficient calculation unit 17 and the flow rate calculation unit 23.

  The coefficient calculation unit 17 is based on the saturated vapor pressure PV input from the saturated vapor pressure deriving unit 15, the pressure P <b> 1 input from the primary pressure acquisition unit 12, and the differential pressure ΔP input from the differential pressure calculation unit 16. And a functional unit for calculating the first coefficient. In the present embodiment, the pressure ratio XF is calculated as the first coefficient. The pressure ratio XF means a ratio composed of the difference between the differential pressure ΔP and the other the pressure P1 or the pressure P2 and the saturated vapor pressure. Specifically, the coefficient calculation unit 17 calculates the pressure ratio XF based on the following equation (2). The calculated pressure ratio XF is output to the determination unit 20 and the flow rate calculation unit 23.

XF = ΔP / (P1-PV) (2)

  From the above equation (2), the determination unit 20 can calculate the pressure ratio XF necessary for determining whether the cavitation flow is dominant in the fluid flow.

  The valve opening obtaining unit 18 is a functional unit that obtains the valve opening θ of the control valve 2 measured by the valve opening sensor 6 from the valve opening sensor 6. The acquired opening degree θ is output to the determination unit 20 and the flow rate calculation unit 23.

  The threshold storage unit 19 is a functional unit that stores a threshold A (θ) used for the determination operation by the determination unit 20. This threshold value A (θ) is a unique value set for each opening degree θ of the control valve 2. Even if the same control valve 2 is used, the pressure ratio at which the cavitation flow becomes dominant also varies depending on the opening degree θ. Therefore, the threshold value storage unit 19 stores the opening degree θ of the control valve 2 set in predetermined value increments, for example, every 1 °, and the threshold value A (θ) corresponding to each opening degree θ. Yes. This makes it possible to determine whether or not the cavitation flow is dominant in the fluid flow.

  The determination unit 20 is a functional unit that determines whether cavitation is dominant in the fluid flow. In the present embodiment, the determination unit 20 includes the pressure ratio XF input from the coefficient calculation unit 17, the opening degree θ input from the valve opening degree acquisition unit 18, and the threshold value A ( and θ). Specifically, the determination unit 20 refers to the threshold storage unit 19 to acquire a threshold value A (θ) corresponding to the opening degree θ input from the valve opening degree acquisition unit 18, and this threshold value A (θ). Is compared with the pressure ratio XF. When the value of XF is smaller than the value of the threshold A (θ) (XF <A (θ)), it is determined that the cavitation flow is not dominant in the fluid flow. On the other hand, when the value of XF is equal to or greater than the value of the threshold A (θ) (XF ≧ A (θ)), it is determined that the cavitation flow is dominant in the fluid flow. This determination result is output to the flow rate calculation unit 23.

The first table 21 is a data table showing the relationship between the opening degree θ and the differential pressure ΔP and the flow coefficient Cv when the cavitation flow is not dominant in the fluid flow. Specifically, as shown in FIG. 3, the opening θ (θ _{1 to} θ _i ) of the control valve 2 set in increments of a predetermined value such as every 1 ° on the vertical axis, and 1 [Pa] on the horizontal axis, for example. A differential pressure ΔP (= X to XXX) set in increments of a predetermined value such as every time is taken, and a flow coefficient Cv (Cvv _{1i to} Cvv _3i ) corresponding to each record is stored.

The second table 22 is a data table showing the relationship between the opening degree θ, the pressure ratio XF, and the flow coefficient Cv when the cavitation flow is dominant in the fluid flow. Specifically, as shown in FIG. 4, the opening θ (θ _{1 to} θ _j ) of the control valve 2 set in increments of a predetermined value such as every 1 ° on the vertical axis and set in increments of a predetermined value on the horizontal axis. The pressure ratio XF (XFv = Y to YYY) is taken, and the flow coefficient Cv (Cvvc _{1j to} Cvvc _3j ) corresponding to each record is stored.

The flow rate calculation unit 23 is a functional unit that calculates the flow rate Q of the fluid passing through the control valve 2. Specifically, the flow rate Q of the fluid currently passing through the control valve 2 is calculated by substituting into the differential pressure ΔP input from the differential pressure calculation unit 16, the flow coefficient Cv, and the above equation (1). To do. The calculated flow rate Q is output to the valve control device 9.
Here, the flow coefficient Cv to be substituted into the above equation (1) is derived as follows.

  When the determination unit 20 determines that the cavitation flow is not dominant in the fluid flow, the flow rate calculation unit 23 refers to the first table 21 and the opening degree θ input from the valve opening degree acquisition unit 18. The flow coefficient Cv corresponding to the differential pressure ΔP input from the differential pressure calculation unit 16 is derived, and the derived flow coefficient Cv is substituted into the above equation (1).

  On the other hand, when the determination unit 20 determines that the cavitation flow is dominant in the fluid flow, the flow rate calculation unit 23 refers to the second table 22 and opens the opening input from the valve opening degree acquisition unit 18. The flow coefficient Cv corresponding to the pressure θ and the pressure ratio XF input from the coefficient calculator 17 is derived, and the derived flow coefficient Cv is substituted into the above equation (1). At this time, since the pressure ratio XF is the pressure ratio XF used in the determination by the determination unit 20, it is not necessary to perform the calculation again, so that the calculation load can be reduced.

  As described above, the flow rate calculation device 8 determines whether or not the cavitation flow is dominant in the fluid flow. If the cavitation flow is not dominant, the first table 21, the case where the cavitation flow is dominant. Since the flow rate is calculated using the flow coefficient derived based on the second table 22, a more accurate flow rate can be obtained.

  Such a flow rate calculation device 8 includes a calculation circuit such as a CPU built in an electric actuator or positioner that is the flow rate control unit 7, a storage circuit such as a memory, and an installed program. That is, the hardware resources and software cooperate to control the hardware resources by a program, and the temperature acquisition unit 11, the primary pressure acquisition unit 12, the secondary pressure acquisition unit 13, and the third table 14 described above. , Saturated vapor pressure derivation unit 15, differential pressure calculation unit 16, coefficient calculation unit 17, valve opening degree acquisition unit 18, threshold value storage unit 19, determination unit 20, first table 21, second table 22, and flow rate calculation unit 23 is realized.

≪Configuration of valve control device≫
As shown in FIG. 5, the valve control device 9 includes a flow rate acquisition unit 31, a set value acquisition unit 32, a valve opening calculation unit 33, and a signal generation unit 34.

  The flow rate acquisition unit 31 is a functional unit that acquires the flow rate Q of the fluid passing through the control valve 2 calculated by the flow rate calculation device 8 from the flow rate calculation device 8. The acquired flow rate Q is output to the valve opening calculation unit 33.

  The set value acquisition unit 32 is a functional unit that acquires a set value Qsp of the flow rate of the fluid that passes through the control valve 2 from a host device that is communicably connected to the flow rate control unit 7. The acquired set value Qsp is output to the valve opening calculator 33.

  Based on the flow rate Q input from the flow rate acquisition unit 31 and the set value Qsp input from the set value acquisition unit 32, the valve opening calculation unit 33 adjusts so that the flow rate Q matches the set value Qsp. This is a functional unit that calculates the opening degree of the valve 2. This calculation result is output to the signal generator 34.

  The signal generator 34 is a functional unit that generates a control signal for setting the opening of the control valve 2 to the opening of the control valve 2 input from the valve opening calculator 33. The generated control signal is output to the control valve 2. Thereby, the opening degree of the control valve 2 is controlled to the opening degree specified by the control signal, and the fluid having a flow rate corresponding to the set value Qsp passes through the control valve 2.

  Similar to the flow rate calculation unit 8, such a valve control unit 9 includes a calculation circuit such as a CPU built in an electric actuator or positioner that is the flow rate control unit 7, a storage circuit such as a memory, and an installed program. Is done. That is, the hardware resources and software cooperate to control the hardware resources by a program, and the flow rate acquisition unit 31, the set value acquisition unit 32, the valve opening calculation unit 33, and the signal generation unit 34 described above are controlled. Realized.

  As described above, according to the present embodiment, the determination unit 20 determines whether or not the cavitation flow is dominant in the fluid flow, and if it is determined that the cavitation flow is not dominant, the cavitation flow is determined. The flow coefficient Cv is derived based on the first table 21 in which the differential pressure ΔP between the pressure P1 and the pressure P2 and the valve opening degree θ and the flow coefficient Cv are stored in association with each other in a non-dominant state, and the cavitation flow Is determined to be dominant, the flow rate is determined based on the second table 22 in which the pressure ratio XF, the valve opening degree θ, and the flow coefficient Cv are stored in association with each other in a state where the cavitation flow is dominant. Since the coefficient Cv is derived and the flow rate Q of the fluid flowing through the control valve 2 is calculated using the flow coefficient Cv derived in this way, the cavitation flow Even if it is dominant it is possible to perform accurate flow control.

  In the present embodiment, a case where the differential pressure ΔP is calculated from the pressure P1 acquired by the primary pressure acquisition unit 12 and the pressure P2 acquired by the secondary pressure acquisition unit 13 by the differential pressure calculation unit 16 will be described as an example. However, a differential pressure gauge may be provided in the flow path 1, and the measurement result of the differential pressure gauge may be used as it is as the differential pressure ΔP. In this case, if at least one of the pressure P1 and the pressure P2 can be acquired, the other can also be calculated from the differential pressure ΔP.

  The present invention can be applied to various systems using a control valve.

  DESCRIPTION OF SYMBOLS 1 ... Flow path, 2 ... Control valve, 3 ... Temperature sensor, 4 ... Primary side pressure sensor, 5 ... Secondary side pressure sensor, 6 ... Valve opening degree sensor, 7 ... Flow control unit, 8 ... Flow rate arithmetic unit, 9 DESCRIPTION OF SYMBOLS ... Valve control apparatus, 11 ... Temperature acquisition part, 12 ... Primary pressure acquisition part, 13 ... Secondary pressure acquisition part, 14 ... 3rd table, 15 ... Saturated vapor pressure derivation part, 16 ... Differential pressure calculation part, 17 ... Coefficient calculation unit, 18 ... valve opening degree acquisition unit, 19 ... threshold value storage unit, 20 ... determination unit, 21 ... first table, 22 ... second table, 23 ... flow rate calculation unit, 31 ... flow rate acquisition unit, 32 ... set value acquisition unit, 33 ... valve opening calculation unit, 34 ... signal generation unit.

Claims (5)

A first pressure that is a pressure of fluid flowing upstream from a throttle portion of the control valve connected to the flow path, a second pressure that is a pressure of fluid flowing downstream from the throttle portion of the control valve, and An acquisition unit that acquires at least two of the differential pressures between the first pressure and the second pressure;
A valve opening degree obtaining unit for obtaining a valve opening degree of the control valve;
Based on at least two of the first pressure, the second pressure, and the differential pressure acquired by the acquisition unit, the first pressure, the first pressure, and the second pressure A coefficient calculation unit for calculating a first coefficient based on the differential pressure and the saturated vapor pressure of the fluid;
The differential pressure between the first pressure and the second pressure, the valve opening, and the flow coefficient are stored in association with each other in a state where the cavitation flow is not dominant in the flow of fluid passing through the control valve. A first table;
A second table that stores the first coefficient, the valve opening, and the flow coefficient in association with each other in a state in which a cavitation flow is dominant in the flow of fluid passing through the control valve;
A determination unit for determining whether a cavitation flow is dominant in a flow of fluid passing through the control valve;
When the determination unit determines that the cavitation flow is not dominant in the flow of fluid passing through the control valve, a flow coefficient is derived based on the differential pressure, the valve opening, and the first table. When the flow rate of the fluid flowing through the control valve is calculated based on the flow coefficient and the differential pressure, and the determination unit determines that cavitation is dominant in the flow of fluid passing through the control valve, A flow rate calculation that derives a flow rate coefficient based on the first coefficient, the valve opening degree, and the second table, and calculates a flow rate of the fluid flowing through the control valve based on the flow rate coefficient and the differential pressure. And a flow rate calculation device. The flow rate calculation device according to claim 1,
The coefficient calculation unit is configured to calculate the first coefficient from XF = ΔP / (P1−PV) where XF is the first coefficient, ΔP is the differential pressure, P1 is the first pressure, and PV is the saturated vapor pressure. A flow rate calculation device that calculates a coefficient of one. The flow rate calculation device according to claim 2,
A storage unit for storing a threshold value set according to the valve opening;
The determination unit compares the first coefficient calculated by the coefficient calculation unit with a threshold value stored in the storage unit, and passes the control valve when the first coefficient is equal to or greater than the threshold value. A flow rate calculation device characterized by determining that the cavitation flow is dominant in the flow of fluid. The flow rate calculation device according to claim 2,
A temperature acquisition unit for acquiring the temperature of the fluid flowing through the flow path;
A third table storing a saturated vapor pressure for each temperature of the fluid, and
The coefficient calculation unit calculates the first coefficient using a saturated vapor pressure derived based on the temperature of the fluid acquired by the temperature acquisition unit and the third table. Flow rate calculation device. A flow rate calculation device that calculates the flow rate of the fluid flowing through the control valve connected to the flow path, and a valve control device that controls the opening of the control valve so that the flow rate calculated by the flow rate calculation device matches a set value. A flow control device comprising:
The flow rate calculation device comprises the flow rate calculation device according to any one of claims 1 to 4.

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