JP2012098218A - Decompression device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve measurement of a gas flow amount inside a fluid conduit installed with a decompression device, without generating losses of primary and secondary pressures in the fluid conduit.SOLUTION: A decompression device 10, which is installed in a fluid conduit 1 and acquires a secondary pressure in a downstream side fluid conduit 1d by reducing a primary pressure in an upstream side fluid conduit 1u, comprises: a secondary pressure detection portion 13 for detecting the secondary pressure; a variable resistance portion 11 for variably adjusting resistance of a gas flow based on the secondary pressure detected at the secondary pressure detection portion 13; and a fixed resistance portion 12 which is provided on the downstream side of the variable resistance portion 11 and has a constant resistance of the gas flow. The pressure is reduced from the primary pressure to the secondary pressure by a combined resistance of the gas flow of the variable resistance portion 11 and the fixed resistance portion 12. The gas flow amount of the fluid conduit 1 can be measured by detecting generated pressure difference at the fixed resistance portion 12.

Description

  The present invention relates to a pressure reducing device that is provided in a fluid conduit and reduces the fluid pressure of an upstream fluid conduit and supplies the fluid pressure to a downstream fluid conduit.

  As a fluid supply system for city gas or the like using a pipeline, a system is adopted in which the high-pressure fluid on the upstream side is decompressed in stages and supplied to the downstream side. At this time, each stage for decompression is equipped with a decompression device (governor) in the fluid conduit.

  In the following description, the pressure in the fluid conduit upstream of the decompression device is referred to as primary pressure, and the pressure in the downstream fluid conduit is referred to as secondary pressure. The pressure reducing device generally includes a valve (main valve) that can adjust the opening degree of an orifice that communicates the upstream fluid conduit and the downstream fluid conduit, and detects the secondary pressure to reduce the opening degree of the valve described above. An automatic pressure adjustment mechanism that maintains the secondary pressure at the set pressure by automatic adjustment is provided.

  The secondary pressure, which is the downstream pressure of the pressure reducing device, varies depending on the amount of fluid consumed at the end of the fluid conduit. The flow rate of the fluid flowing through the pressure reducing device is important in grasping the amount of fluid consumed at the end of the fluid conduit. In order to measure this flow rate, the valve opening is measured using some mechanism, and the flow rate is estimated from the pressure difference between the upstream and downstream sides of the valve and the valve opening (governor opening method), There is a method (flow meter insertion method) in which a flow meter is installed upstream or downstream of the decompression device regardless of the mechanism of the decompression device. Patent Document 1 listed below describes a governor opening meter for measuring the opening of a valve in a decompression device.

JP 2000-18986 A

  If the governor opening method described above is used to measure the flow rate of the fluid flowing through the pressure reducing device, it is necessary to incorporate a complicated mechanism into the valve operating mechanism of the pressure reducing device in order to measure the valve opening. Therefore, there arises a problem that the maintenance is complicated and the cost of the decompression device is increased.

  On the other hand, when the above-described flow meter insertion method is employed to measure the flow rate of the fluid flowing through the pressure reducing device, the pressure loss of the primary pressure and the secondary pressure becomes a problem. Generally, a differential pressure type flow meter, a Karman vortex type flow meter, or the like is used as the flow meter. However, since these flow meters include a resistance element in the flow path, a pressure loss due to the resistance element increases when a large flow rate passes. For this reason, when a flow meter is installed on the upstream side of the decompression device, the primary pressure is lowered due to the pressure loss of the flow meter, and there arises a problem that the transport capacity for sending the fluid downstream is lowered. In addition, when a flow meter is installed on the downstream side of the decompression device, a pressure loss due to the flow meter is added to the secondary pressure set by the decompression device, so that fluid can be supplied downstream with a desired secondary pressure. A problem that cannot be done arises.

  This invention makes it an example of a subject to cope with such a problem. That is, when measuring the flow rate of a fluid conduit equipped with a pressure reducing device, the flow rate can be measured without incorporating a complicated mechanism in the pressure reducing device, and without causing a pressure loss in the primary pressure or the set secondary pressure. An object of the present invention is to be able to perform flow rate measurement.

In order to achieve such an object, the decompression device according to the present invention has at least the following configuration.
A pressure reducing device that is provided in a fluid conduit and reduces a primary pressure in an upstream fluid conduit to obtain a secondary pressure in a downstream fluid conduit, the secondary pressure detecting unit detecting the secondary pressure, and the secondary pressure A variable resistance section that variably adjusts the flow resistance based on the secondary pressure detected by the pressure detection section; and a fixed resistance section that is provided on the downstream side of the variable resistance section and has a constant flow resistance. A pressure reducing device that reduces the primary pressure to the secondary pressure by a combined resistance of a resistance portion and the fixed resistance portion.

  In the decompression device having such a feature, the flow rate of the fluid conduit can be obtained from the flow resistance of the known fixed resistance portion and the detected generated differential pressure by detecting the generated differential pressure due to the fixed resistance portion. According to this, when measuring the flow rate of a fluid conduit equipped with a pressure reducing device, the flow rate can be measured without incorporating a complicated mechanism in the pressure reducing device, causing a pressure loss in the primary pressure or the set secondary pressure. The flow rate can be measured without any problems.

It is explanatory drawing explaining the decompression device which concerns on embodiment of this invention. It is explanatory drawing explaining the decompression device concerning other embodiments of the present invention. It is explanatory drawing explaining the decompression device concerning other embodiments of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing a basic configuration of a decompression device according to an embodiment of the present invention. The decompression device 10 is provided in the fluid conduit 1 and decompresses the primary pressure in the upstream fluid conduit 1u of the fluid conduit 1 to obtain the secondary pressure in the downstream fluid conduit 1d.

  The decompression device 10 includes a variable resistance unit 11, a fixed resistance unit 12, and a secondary pressure detection unit 13. The variable resistance unit 11 can variably adjust the flow resistance based on the secondary pressure detected by the secondary pressure detection unit 13, and a valve mechanism that variably adjusts the flow resistance by adjusting the opening degree. It is constituted by. As an example, an orifice opening 11a, a valve mechanism 11b for adjusting the opening of the orifice opening 11a, and a drive unit 11c for driving the valve mechanism 11b are provided. In the illustrated example, the secondary pressure detected by the secondary pressure detection unit 13 is the driving pressure of the driving unit 11c, and the flow resistance is variably adjusted by the operation of the driving unit 11c. The variable resistance portion 11 has an automatic adjustment function for operating the valve mechanism 11b to open the opening of the orifice opening portion 11a and maintaining the secondary pressure at a set pressure when the secondary pressure is lowered.

  The fixed resistor 12 is provided on the downstream side of the variable resistor 11 and has a constant flow resistance. The fixed resistance portion 12 may be anything as long as the relationship between the generated differential pressure and the flow rate is measured in advance, and can be configured by an orifice (throttle) or a venturi. The decompression device 10 reduces the primary pressure in the upstream fluid conduit 1u to the secondary pressure in the downstream fluid conduit 1d by the combined resistance of the variable resistor portion 11 and the fixed resistor portion 12.

  According to such a pressure reducing device 10, the flow rate of the fluid conduit 1 can be estimated by detecting the differential pressure generated by the fixed resistance portion 12. More specifically, a differential pressure detector 12a that detects a differential pressure generated by the fixed resistor 12 is provided, and the flow rate Q of the fluid conduit 1 is obtained from the detected differential pressure ΔP. Since the relationship (flow resistance) between the flow rate Q and the generated differential pressure ΔP is measured in advance, the fixed resistance unit 12 can determine the flow rate Q from the generated differential pressure ΔP detected using this relationship.

  According to the decompression device 10 according to such an embodiment, since the flow meter is not installed in the upstream fluid conduit 1u through which the primary pressure fluid flows, the primary pressure does not decrease due to the pressure loss of the flow meter. In addition, since the flow meter is not installed in the downstream fluid conduit 1d through which the fluid of the secondary pressure flows, the secondary pressure is not lowered due to the pressure loss of the flow meter. Furthermore, regardless of the operation of the valve mechanism 11b for adjusting the opening of the orifice opening 11a, the flow rate of the fluid conduit 1 is controlled by the generated differential pressure of the fixed resistance portion 12 having a constant resistance even when the secondary pressure is adjusted. Therefore, it is not necessary to add a complicated mechanism for measuring the valve operation to the decompression device 10.

  2 and 3 are explanatory views showing other embodiments of the present invention (the parts common to the above-described embodiments are denoted by the same reference numerals and the duplicate description is partially omitted). Similarly to the embodiment shown in FIG. 1, the decompression device 10 according to this embodiment also includes a variable resistance unit 11, a fixed resistance unit 12, and a secondary pressure detection unit 13.

  The variable resistance unit 11 variably adjusts the flow rate of the pilot flow path 20 that connects the upstream fluid conduit 1 u and the downstream fluid conduit 1 d based on the secondary pressure, and changes according to the flow rate of the pilot flow path 20. The flow resistance is variably adjusted by the operation of the driving unit 11c that operates according to the driving pressure. That is, the pilot valve 14 is provided in the pilot flow path 20 that communicates the upstream fluid conduit 1u and the downstream fluid conduit 1d.

  The pilot valve 14 adjusts the opening degree of the valve by using the secondary pressure detected by the secondary pressure detecting unit 13 as a driving pressure, and the flow rate of the fluid flowing through the pilot flow path 20 varies depending on the opening degree of the pilot valve 14. . Since the pressure loss at the pilot valve 14 and the resistance portion 15 where the flow rate of the fluid flowing through the pilot flow path 20 changes, the drive pressure of the drive pressure flow path 21 branched from the pilot flow path 20 changes. The drive part 11c of the variable resistance part 11 operates by the change of the drive pressure.

  Therefore, in the embodiment shown in FIG. 2, when the secondary pressure decreases, the pilot valve 14 opens, the flow rate of the pilot flow channel 20 increases, and the drive pressure of the drive pressure flow channel 21 is increased by the flow rate increase of the pilot flow channel 20. The drive unit 11c operates the valve mechanism 11b in the opening direction. As a result, the secondary pressure is automatically adjusted to the set pressure. This pressure reducing device 10 also reduces the primary pressure to the secondary pressure by the combined resistance of the variable resistance portion 11 and the fixed resistance portion 12 as in the embodiment shown in FIG.

  On the other hand, in the embodiment shown in FIG. 3, when the secondary pressure decreases, the pilot valve 14 opens, thereby reducing the pressure loss in the pilot valve 14 and increasing the driving pressure in the driving pressure channel 21. The unit 11c automatically adjusts the secondary pressure to the set pressure by operating the valve mechanism 11b in the opening direction. This pressure reducing device 10 also reduces the primary pressure to the secondary pressure by the combined resistance of the variable resistance portion 11 and the fixed resistance portion 12 as in the embodiment shown in FIG.

  Also in the embodiment shown in FIGS. 2 and 3, the fixed resistance portion 12 is provided on the downstream side of the variable resistance portion 11, and the flow rate of the fluid conduit 1 is estimated by detecting the differential pressure generated by the fixed resistance portion 12. can do. More specifically, a differential pressure detection unit 12a that detects a generated differential pressure due to the fixed resistance unit is provided, and the flow rate Q of the fluid conduit 1 is obtained from the detected generated differential pressure ΔP. Since the relationship (flow resistance) between the flow rate Q and the generated differential pressure ΔP is measured in advance, the fixed resistance unit 12 can determine the flow rate Q from the generated differential pressure ΔP detected using this relationship.

  In the decompression device 10 according to such an embodiment, the pressure loss due to flow measurement does not affect the primary pressure or the secondary pressure. Therefore, the variable resistance portion 11 can be operated by changing the flow rate of the pilot flow path 20 regardless of the flow rate measurement. Similarly to the above-described embodiment, since the flow meter is not installed in the upstream fluid conduit 1u through which the primary pressure fluid flows, the primary pressure does not decrease due to the pressure loss of the flow meter, and the secondary pressure fluid Since the flow meter is not installed also in the downstream fluid conduit 1d through which the secondary gas flows, the secondary pressure is not lowered by the pressure loss of the flow meter.

  As described above, according to the decompression device 10 according to the embodiment of the present invention, by detecting the generated differential pressure due to the fixed resistance unit 12, the flow resistance of the known fixed resistance unit 12 and the detected generated differential pressure are used. The flow rate of the fluid conduit can be determined. According to this, when the flow rate of the fluid conduit 1 equipped with the pressure reducing device 10 is measured, not only can the flow rate be measured without incorporating a complicated mechanism in the pressure reducing device 10, but also the primary pressure or the set secondary pressure can be adjusted. The flow rate can be measured without causing pressure loss.

1: fluid conduit, 1u: downstream fluid conduit, 1d: upstream fluid conduit,
10: decompression device,
11: Variable resistance part,
11a: orifice opening, 11b: valve mechanism, 11c: drive unit,
12: Fixed resistance part, 12a: Differential pressure detection part,
13: Secondary pressure detector, 14: Pilot valve,
20: Pilot flow path, 21: Drive pressure flow path

Claims (5)

A pressure reducing device mounted on a fluid conduit to reduce a primary pressure in an upstream fluid conduit to obtain a secondary pressure in a downstream fluid conduit;
A secondary pressure detector for detecting the secondary pressure;
A variable resistance unit that variably adjusts the flow resistance based on the secondary pressure detected by the secondary pressure detection unit;
A fixed resistance portion provided downstream of the variable resistance portion and having a constant flow resistance;
A pressure reducing device that reduces the primary pressure to the secondary pressure by a combined resistance of the variable resistance portion and the fixed resistance portion. A differential pressure detection unit that detects a differential pressure generated by the fixed resistance unit;
The pressure reducing device according to claim 1, wherein the flow rate of the fluid conduit is obtained from the generated differential pressure.   The decompression device according to claim 1, wherein the variable resistance unit is configured by a valve mechanism that variably adjusts a flow resistance by adjusting an opening degree.   4. The variable resistance unit variably adjusts a flow resistance by an operation of a drive unit that uses a secondary pressure detected by the secondary pressure detection unit as a drive pressure. Pressure reducing device.   The variable resistance unit variably adjusts the flow rate of the pilot flow path that connects the upstream fluid conduit and the downstream fluid conduit based on the secondary pressure, and changes in accordance with the flow rate of the pilot flow path The pressure reducing device according to any one of claims 1 to 3, wherein the flow resistance is variably adjusted by an operation of a driving unit that operates by pressure.

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