JPH0774975B2 - Pressure reducing valve for steam with flow rate measurement function - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure reducing valve which is attached to a steam piping system to keep a steam pressure on a secondary side at a constant set pressure, and particularly to a pressure reducing valve for steam also having a flow rate measuring function. Regarding

Steam is most widely used as a heat source in various production processes. The steam generated by the boiler etc.
A pressure reducing valve is used to reduce the pressure to a pressure suitable for each production process. The pressure reducing valve allows the most productive steam to be supplied with the optimum pressure or temperature for keeping the quality of the product constant. In addition, it is important to understand the thermal energy consumption in each production process and to measure and monitor the amount of steam used, that is, the steam flow rate, in order to minimize energy loss while maintaining productivity.

Conventional Technology Conventionally, as a steam flow meter, for example, an area flow meter,
The amount of steam used was measured by individually installing a differential pressure type flowmeter, an overflow meter, an ultrasonic flowmeter, and the like.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention When the steam flowmeters are individually installed, the piping system becomes complicated and the mounting is complicated, and the flowmeters themselves are expensive and the equipment cost is low. There was a problem.

Therefore, the technical problem of the present invention is to make it possible to measure the flow rate inexpensively without the need to separately install a steam flow meter.

Means for Solving the Problems Technical means of the present invention taken to solve the above problems, a pressure reducing valve for maintaining the pressure on the secondary side at a predetermined set pressure is attached to a steam pipe, and the pressure reducing valve is attached to the pressure reducing valve. In a gas / liquid separation unit and a liquid discharge valve, pressure detecting members for detecting the respective pressure values are arranged on the primary side and the secondary side of the main valve opening of the pressure reducing valve, and the pressure detecting member is arranged on the secondary side of the pressure reducing valve. A temperature detecting member for detecting a temperature value is arranged, and a dryness calculating means for calculating the dryness of the steam passing through the pressure reducing valve from the pressure value and the temperature value, and a liquid discharge valve provided in the pressure reducing valve are discharged. A liquid amount measuring member for measuring the liquid amount is arranged, and the flow rate calculating means calculates the dry vapor amount or the total fluid amount passing through the pressure reducing valve from the dryness and the liquid amount.

Action The pressure reducing valve supplies high-pressure primary-side steam to the secondary side as constant low-pressure steam by the throttling action of its main valve opening. Therefore, the steam passing through the pressure reducing valve is necessarily throttled and undergoes an isenthalpic change due to adiabatic expansion. The steam pressure on the primary side before the isenthalpic change, and the steam pressure and steam temperature on the secondary side after the change are detected by the detection members, and input to the calculation unit to use the known calculation formula. Can be calculated by calculating the dryness of.

That is, it is obtained from the Moliere diagram, or the enthalpy of saturated water at primary steam pressure: I1 ′, the enthalpy of saturated steam at primary steam pressure: I1 ″, the enthalpy of superheated steam at secondary side: I2, and the degree of dryness X'is Can be obtained by the dryness calculation means.

Further, when the steam pressure changes, it can be measured by changing the set pressure on the secondary side by the set pressure changing means generally provided in the pressure reducing valve to obtain a predetermined pressure reducing ratio.

If it is necessary to measure the dryness of the vapor more accurately, the pressure reducing valve shall be insulated with a heat insulating material.

The liquid (condensed water) contained in the wet steam is separated by the gas-liquid separation unit, discharged from the liquid discharge valve, and the amount thereof is measured by the liquid amount measuring member.

When the dryness and the amount of liquid (condensed water) are obtained, Q0 ・ I1−Qd ・ I1 ′ ＝ (Q0−Qd) ・ I2 where, Q0: Total fluid amount before gas-liquid separation part Qd: At gas-liquid separation part Amount of liquid to be separated I1: Enthalpy of wet steam I1 ′: Enthalpy of saturated primary water I2: Enthalpy of secondary steam I1 = I1 ′ + X (I1 ″ −I1 ′) X: Dryness of wet steam I1 ″: From the relational expression that is the enthalpy of the primary-side saturated vapor and the relational expression that X ′ / X = 1 / α, where α is the separation efficiency in the gas-liquid separation section that is clarified at the time of normal design, The equations hold, and Qd is obtained as the amount of liquid and X ′ is obtained as the degree of dryness, and Q0, that is, the total amount of fluid flowing into the pressure reducing valve equipped with the gas-liquid separator is obtained by the flow rate calculation means. . Also, the amount of dry steam passing through the pressure reducing valve can be obtained from (Q0-Qd) .X '.

Effect of the invention The dryness of steam is obtained by utilizing the throttling action of the pressure reducing valve,
The vapor flow rate can be obtained from the dryness and the liquid amount. Therefore, a separate steam flow meter is not needed. That is,
It is possible to measure not only the liquid amount but also the dry vapor amount and the total fluid amount only by adding the liquid amount measuring member to the pressure reducing valve having the gas-liquid separating section and the liquid discharge valve of which the separation efficiency is known.

The dryness of wet steam passing through normal steam piping is 90%
Before and after, the liquid amount measuring member may measure a flow rate of about 10% of the total fluid amount, and can be made small and inexpensive.

Example An example showing a specific example of the above technical means will be described.
(Refer to FIG. 1) The pressure reducing valve of the present embodiment includes a pressure reducing valve section 1, a gas-liquid separating section 2 for separating a liquid component in passing vapor, and a liquid discharge valve 3 for discharging the separated liquid component to the outside of the system. A setting drive unit 4 for automatically setting the pressure setting of the pressure reducing valve, a calculation unit 5 for performing various calculations, a primary pressure sensor 6 as a pressure detecting member attached to the primary side of the pressure reducing valve, and a secondary side It is composed of a secondary pressure sensor 7 attached, a temperature sensor 8 as a temperature detecting member also attached to the secondary side, and a liquid amount measuring member 9.
Each sensor 6, 7, 8 has a primary side pipe 60 and a secondary side pipe 6
1 Install on top. However, it is more preferable that the primary-side pressure sensor 6 is attached to the secondary side of the gas-liquid separating section 2, that is, the primary side of the main valve port 14 of the pressure reducing valve described below.

The pressure reducing valve unit 1 includes a valve casing 10 having an inlet 12, a main valve port 14, and an outlet.
16 are formed. Inlet 12 is the primary high-pressure fluid source, outlet
16 is connected to the secondary side low pressure area. The main valve port 14 is formed by the valve seat member 13.

The piston 20 is slidably arranged in the cylinder 22, and the piston rod 15 is brought into contact with the main valve 18 through the main valve port 14.

A pilot valve 26 is arranged in a primary pressure passage 24 that connects the inlet 12 and the upper space of the piston 20, that is, the piston chamber 17.

The diaphragm 28 is attached with its outer peripheral edge sandwiched between the flanges 30 and 32. The space below the diaphragm 28 communicates with the outlet 16 through the secondary pressure passage 34. In addition, the pilot valve 26
The head end face of the valve rod 36 comes into contact with the central lower face of the diaphragm 28. The valve rod 36 is pressed against the diaphragm 28 by the primary side fluid pressure and the elastic force of the coil spring that biases the valve body of the pilot valve 26.

A spring seat 38 is placed on the upper surface of the diaphragm 28, and a coil spring 40 for setting pressure is arranged between the spring seat 38 and the spring receiver 42.

The tip of the output shaft 52 of the drive motor 51 arranged in the cover 50 of the setting drive unit 4 is brought into contact with the spring receiver 42. Due to the rotation of the drive motor 51, the spring bearing 42 is displaced up and down, and the elastic force that pushes down the diaphragm 28 of the pressure setting spring 40 changes.
With the elastic force of the pressure setting spring 40 as a reference value, the diaphragm 28 bends according to the secondary pressure acting on the lower surface of the diaphragm 28, and the valve rod 36 is displaced to open / close the pilot valve 26. As a result, the primary fluid is introduced into the piston chamber 17,
The piston 20 is driven and the main valve 18 is displaced. Reference numeral 66 is a control unit including a setting unit (not shown) for performing pressure setting. Further, reference numeral 65 is a display unit for displaying the set pressure, the dryness of the vapor calculated as described below, the flow rate of the dry vapor, the total fluid amount, and the like.

The gas-liquid separation unit 2 swirls vanes 55 that swirl the steam that has flowed in from the inlet 12 through the screen 19, and the steam that has swirled to separate its liquid component by centrifugal force reaches the main valve port 14. And a cylindrical partition member 56 for. Piston 20
Is driven and the main valve 18 is displaced, steam at the inlet 12 flows through the main valve opening 14 to the outlet 16. This automatically operates so that the main valve opening 14 opens when the steam pressure on the secondary side decreases, and closes when the steam pressure increases.

The liquid discharge valve 3 is for automatically discharging the amount of the liquid separated in the gas-liquid separation unit 2 along the inner circumference of the valve casing 10 and collecting the liquid. The hollow float 57 is covered with the float cover 58.
Trap valve seat 59, which is covered with and is placed facing the float 57.
Is attached, and the outlet side 70 of the trap valve seat 59 is connected to the liquid amount measuring member 9.

The liquid amount measuring member 9 is formed by mounting a liquid flow meter 11 capable of measuring only the liquid discharged from the liquid discharge valve 3 via a switching valve 71, and inputs the measurement result to the arithmetic unit 5 via a signal line 72. To do. It is not always necessary to use a flow meter as the liquid amount measuring member 9, and for example, simply, it can be obtained by receiving the liquid discharged from the liquid discharge valve 3 with a bucket or the like and measuring the weight thereof. .

In the wet vapor containing the liquid component that has flowed in from the inlet 12, the liquid component in the form of water drops is separated by the centrifugal force in the gas-liquid separation unit 2, and the dryness is relatively high.

When measuring the dryness: X ', the primary side pressure sensor 6 attached to the primary side pipe 60 detects the primary side steam pressure P1 while the detected value of the temperature sensor 8 is stable, and at the same time, the main valve port 14 is turned on. The secondary side pressure sensor 7 detects the pressure P2 of the steam that has passed and is throttled, and the temperature sensor 8 detects the temperature T2, and inputs the temperature T2 to the calculation unit 5, whereby the dryness calculation means ( It is calculated by a known method from the Moliere diagram stored in a storage unit (not shown) and a storage unit (not shown).

Alternatively, to obtain a more accurate value, the enthalpy I1 ′ of saturated water at the primary steam pressure P1 and the enthalpy I1 ″ of saturated steam at the primary steam pressure P1 are also stored from the saturated steam table and the superheated steam table, which are also stored. Determine the enthalpy I2 of superheated steam at the secondary steam pressure P2 and temperature T2, It can be calculated from the formula. When this formula is used, calculation cannot be performed unless the steam on the secondary side becomes superheated steam. However, in this embodiment, the gas-liquid separation unit 2 is incorporated in the pressure reducing valve, so that the main valve opening of the pressure reducing valve is reduced. The dryness of the steam immediately before being throttled at 14 becomes relatively high, and the steam after passing through the main valve port 14 is likely to become overheated steam, and therefore, the calculation can be performed using the above equation.

When the dryness of the vapor passing through the main valve port 14 and the amount of liquid separated by the gas-liquid separation unit 2 are obtained, the flow rate calculation means (not shown) in the calculation unit 5 determines the dryness based on the above calculation formula. The steam flow rate and total fluid volume can be determined.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram showing an embodiment of a pressure reducing valve for steam having a flow rate measuring function of the present invention. 1: Pressure reducing valve part, 2: Gas-liquid separation part 3: Liquid discharge valve, 4: Setting drive part 5: Calculation part, 6: Primary side pressure sensor 7: Secondary side pressure sensor, 8: Temperature sensor 9: Liquid amount Measuring member, 14: Main valve opening

Claims (1)

[Claims] 1. A main valve opening of a pressure reducing valve in which a pressure reducing valve for maintaining a pressure on the secondary side at a predetermined set pressure is attached to a steam pipe, and the pressure reducing valve is provided with a gas-liquid separation section and a liquid discharge valve. A pressure detecting member for detecting each pressure value is arranged on the primary side and the secondary side, and a temperature detecting member for detecting the temperature value is arranged on the secondary side of the pressure reducing valve. The dryness calculating means for calculating the dryness of the vapor passing through the pressure reducing valve, and the liquid amount measuring member for measuring the amount of liquid discharged from the liquid discharge valve provided in the pressure reducing valve are arranged. A steam pressure reducing valve having a flow rate measuring function, comprising: a flow rate calculating means for calculating the amount of dry steam or the total amount of fluid passing through the pressure reducing valve.