JP2009198472A - Device and method for measuring high-pressure gas flow - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide device and method for measuring high-pressure gas flow which can correctly measure flow rate of high-pressure gas because use of large diameter orifice diffuser with orifice enables accurate measuring of flow coefficient even if pressure in high-pressure tank significantly varies. <P>SOLUTION: This high-pressure gas flow measuring device measures flow rate of high-pressure gas contained in the high-pressure tank when feeding out the above high-pressure gas through high-pressure piping. It is characterized by that inlet of the large diameter orifice diffuser with its outlet end open to the atmosphere is connected with outlet of the above high-pressure piping, while this orifice diffuser is provided with both orifice and differential manometer for detecting anteroposterior differential pressure of the orifice at an adequate position from the above inlet, and the distance from the above outlet of the orifice is set to the position where pressure of the gas spouted into the orifice diffuser from the above outlet may become near the level of atmospheric pressure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a high-pressure gas flow rate measuring apparatus and a flow rate measuring method for measuring the flow rate of a high-pressure gas stored in a high-pressure tank such as a hydrogen cylinder to the outside through a high-pressure pipe.

When the gas leaks from the high-pressure tank in which the high-pressure gas is stored or when the gas is released, it may be necessary to measure the flow rate of the released gas.
In general, since the high pressure gas is choked at the outlet and becomes sonic, if the expansion process in the outlet hole is isentropic, the discharge flow rate can be estimated from outlet area × gas flow velocity × gas density.

However, in the actual outlet hole portion, there is a pressure loss associated with a change in area from the high-pressure pipe portion, and the like, which is often different from a pressure drop due to a theoretical expansion process. In addition, a gas such as hydrogen often exhibits a behavior different from the theoretical formula of an ideal gas in a high pressure region due to an intermolecular force effect called a real gas effect.
As described above, since the gas sound speed and the gas density change in the expansion process at the outlet hole, it is generally difficult to specify the gas sound speed and the gas density in the portion where the area is limited as the gas outlet.

As a means for solving this problem, when the pressure change in the high-pressure tank 1 is small as shown in FIG. 4A, the high-pressure gas in the high-pressure tank 1 is discharged through the high-pressure pipe 2 connected to the high-pressure tank 1. , when the pressure change of the pressure P ₁ in the high-pressure tank 1 that is detected by the pressure gauge 15 is small, and calculates the flow rate per time from the pressure change P ₁ and the release time of the high-pressure tank 1, by the pressure gauge 16 The theoretical flow rate is calculated by detecting the pressure P ₂ at the outlet of the high-pressure pipe 2, the flow coefficient at the outlet is calculated from the ratio of the flow rate per time to the calculated value, and the flow coefficient and the pre-nozzle pressure are calculated. The actual flow rate is estimated by

In addition, Patent Document 1 (Japanese Utility Model Publication No. 4-75914) has a communication hole that is sandwiched between a pair of flanges of a pipe through which a gaseous fluid flows and that penetrates inward and outward at a position spaced forward and backward. A ring-shaped spacer, an orifice plate disposed inside the spacer so as to intersect the flow path of the gaseous fluid, and an edge portion of the orifice plate and a separation position of the communication hole in the inner surface n spacer of the spacer A support ring which is arranged in a connected state and deforms due to a radial displacement of the orifice plate, and a pressure transmission pipe which is connected to the outside of the pair of communication holes of the spacer and guides the pressure at the front and rear positions of the orifice plate to the outside With
By placing a displacement on the support ring portion, the deformation when the orifice plate is relatively thermally expanded is absorbed by the support ring, and the concentration of thermal stress on the attachment portion between the orifice plate and the spacer is reduced. is doing.

Japanese Utility Model Publication No. 4-75914

FIG. 4 is a schematic diagram of an apparatus for measuring the flow rate of high-pressure gas delivered from a high-pressure tank containing high-pressure gas. FIG. 4 (A) shows a case where the pressure change in the high-pressure tank is small. ) Shows the case where the pressure change in the high-pressure tank is remarkably large.
As shown in FIG. 4A, when the pressure change in the high-pressure tank 1 is small, that is, as described above, the high-pressure gas in the high-pressure tank 1 is discharged through the high-pressure pipe 2 connected to the high-pressure tank 1, If the pressure change of the pressure P ₁ in the high-pressure tank 1 that is detected by the pressure gauge 15 is small, and calculates the flow rate per time from the pressure change P ₁ and the release time of the high-pressure tank 1, high pressure by the pressure gauge 16 calculating a theoretical flow rate by detecting the pressure P ₂ of the pipe 2 outlets, to calculate the flow coefficient of the outlet in the high-pressure pipe 2 from the ratio between the calculated value flow rate per said time, the flow coefficient of the actual measurement Used.

However, when the pressure change in the high-pressure tank 1 is remarkably large as in the pressure P ₃ detected by the pressure gauge 15 as shown in FIG. 4 (B), it is difficult to calculate the flow rate every hour. as the pressure change P ₄ detected by the meter 16, significantly largely changed, it can not be maintained at a predetermined pressure, in such a case it is difficult to measure the flow coefficient, inevitably actual error measurement.

  In view of the problems of the prior art, the present invention makes it possible to accurately measure the flow coefficient even when the pressure change in the high-pressure tank is large by using a large-diameter orifice expansion pipe with an orifice, and to control the flow rate of the high-pressure gas. An object of the present invention is to provide a high-pressure gas flow rate measuring device and a high-pressure gas flow rate measuring method capable of accurately measuring.

  The present invention achieves such an object. In a high-pressure gas flow measuring device that measures the flow rate of a high-pressure gas stored in a high-pressure tank to the outside through the high-pressure pipe, the outlet of the high-pressure pipe is provided. And a differential pressure gauge for detecting a pressure difference between the orifice and the front and back of the orifice at an appropriate position from the inlet portion. The distance from the outlet portion of the orifice is set to a position where the pressure of the gas ejected from the outlet portion into the orifice expansion pipe is close to the atmospheric pressure (Claim 1). ).

In this invention, specifically,
The outlet portion of the high-pressure pipe is configured as a predetermined throttle portion, and the orifice expanding pipe is formed in a cylindrical body having a predetermined length with the cross-sectional area rapidly expanding from the throttle portion, and the orifice and A differential pressure gauge is provided (Claim 2).

Moreover, the high pressure gas flow rate measuring method according to the present invention includes:
A high-pressure gas flow measurement method for measuring the flow rate of a high-pressure gas stored in a high-pressure tank to the outside through a high-pressure pipe, wherein a large-diameter orifice expansion pipe is provided at the outlet of the high-pressure pipe. An orifice is set at a position where the pressure of the gas injected into the orifice expansion pipe is close to the atmospheric pressure, and the differential pressure of the orifice is detected near the atmospheric pressure. ).

The use means of the high-pressure gas flow measuring device according to the present invention is:
(1) In a high-pressure gas flow measuring device that measures the flow rate of hydrogen gas when the hydrogen gas stored in a high-pressure hydrogen cylinder is sent to the outside through a leak gas pipe,
A large-diameter orifice expanding pipe whose outlet end is open to the atmosphere is buried in the ground, and the outlet portion of the leak gas pipe is buried in the ground and connected to the inlet of the orifice expanding pipe. An orifice and a differential pressure gauge for detecting the pressure difference between the front and back of the orifice are provided at appropriate positions from the inlet, and the distance from the outlet of the leak gas pipe of the orifice is the hydrogen gas ejected from the outlet into the orifice expansion pipe Is set at a position where the pressure is near atmospheric pressure.

  (2) In a high-pressure gas flow measuring device that measures the flow rate of the high-pressure gas when the high-pressure gas stored in the high-pressure tank is sent to the outside through the high-pressure pipe, a safety valve is provided in the middle of the high-pressure pipe, and the safety valve outlet The high-pressure pipe is connected to the inlet of a large-diameter orifice expansion pipe, and the orifice expansion pipe is provided with a differential pressure gauge for detecting a pressure difference between the orifice and the orifice at a proper position from the inlet portion. The distance from the outlet is set to a position where the pressure of the gas ejected from the inlet through the safety valve into the orifice expansion pipe is close to the atmospheric pressure (Claim 5).

The present invention connects an outlet end of a high-pressure pipe connected to a high-pressure tank to an inlet of a large-diameter orifice expanding pipe opened to the atmosphere, and the orifice expanding pipe is positioned at an appropriate position from the inlet section. A differential pressure gauge for detecting the pressure difference between the orifice and the front and back of the orifice is provided, and the distance of the orifice from the outlet portion is such that the pressure of the gas ejected from the outlet portion into the orifice expansion pipe is close to the atmospheric pressure. (Claims 1 and 3), specifically, the outlet portion of the high-pressure pipe is configured as a predetermined throttle portion, and the orifice expansion pipe is a cylinder having a predetermined length whose cross-sectional area is rapidly expanded from the throttle portion. Since the orifice and the differential pressure gauge are provided in the middle of the cylindrical body (Claim 2),
When the high-pressure gas in the high-pressure tank flows from the high-pressure pipe into the orifice expansion pipe formed in a cylindrical body of a predetermined length whose cross-sectional area has expanded rapidly through the throttle, the cross-sectional area of the orifice expansion pipe rapidly increases. As this happens, it suddenly expands and the pressure drops. In this case, there is no influence on the gas on the high-pressure piping side.

The expansion distance of the pressure from the outlet portion of the high-pressure pipe of the orifice is set to a position where the pressure of the gas injected from the outlet portion into the orifice expansion pipe is close to the atmospheric pressure. Gas that has fallen in the vicinity of the atmospheric pressure is supplied, and measurement by a differential pressure gauge that detects a pressure difference before and after a normal orifice is possible. Even when the pressure change in the high-pressure tank is large, the flow coefficient can be accurately measured.
Therefore, a high-pressure gas flow measuring device that can accurately measure the flow rate of the high-pressure gas is obtained.

Further, a large-diameter orifice expanding pipe whose outlet end is open to the atmosphere is buried in the ground, and the outlet portion of the leak gas pipe is buried in the ground and connected to the inlet of the orifice expanding pipe. A differential pressure gauge that detects the pressure difference between the orifice and the front and back of the orifice is provided at an appropriate position from the inlet, and the distance from the outlet of the leak gas pipe of the orifice is the distance of the gas jetted into the orifice expansion pipe from the outlet If the pressure is set at a position close to atmospheric pressure (Claim 4),
The expansion distance of the pressure from the inlet of the leak gas piping of the hydrogen gas stored in the high-pressure hydrogen cylinder is set to a position where the pressure of the hydrogen gas ejected from the inlet into the orifice expansion pipe is close to the atmospheric pressure. Therefore, the hydrogen gas that has dropped to near atmospheric pressure is supplied to the orifice, and measurement with a differential pressure gauge that detects the pressure difference before and after the normal orifice is possible without affecting the leak gas piping side. Can be measured.

In addition, a safety valve is provided in the middle of the high-pressure pipe through which the high-pressure gas stored in the high-pressure tank flows, and the high-pressure pipe at the outlet of the safety valve is connected to the inlet of the large-diameter orifice expansion pipe. An orifice and a differential pressure gauge for detecting a pressure difference between the front and the back of the orifice are provided at an appropriate position from the inlet, and the distance of the orifice from the outlet is a gas jetted from the inlet to the orifice expansion pipe through the safety valve. If the pressure is set to a position near the atmospheric pressure (Claim 5),
Connected to the inlet of the large-diameter orifice expansion pipe downstream of the safety valve, the distance of the orifice from the outlet portion is such that the pressure of the gas ejected from the inlet portion through the safety valve into the orifice expansion tube is close to the atmospheric pressure. Since the position is set to such a position, the operation of the safety valve can be performed without any influence, and the measurement of the flow rate by the orifice expansion pipe can be performed without any trouble.

  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

FIG. 1 is a configuration diagram of a flow rate measuring device for a high-pressure tank showing a first embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes a high-pressure tank in which high-pressure gas is stored, and a high-pressure pipe 2 is connected to the high-pressure tank 1. Reference numeral 4 denotes an orifice expansion pipe to which the high pressure pipe 2 is connected. An outlet portion of the high-pressure pipe 2 connected to the orifice expansion pipe 4 is formed in a nozzle 3 having a choke portion (throttle portion).
The orifice expanding pipe 4 is formed in a cylindrical body having a predetermined length with a cross-sectional area rapidly expanding from the nozzle 3, and the orifice 5 and the pressure tap 6 on the inlet side of the orifice 5 and the orifice 5 on the outlet side in the middle of the cylindrical body. A pressure tap 7 is installed, and a differential pressure from the pressure taps 6 and 7 is detected by a pressure sensor 8.

The distance L of the orifice 5 from the nozzle 3 is set at a position where the pressure of the gas ejected from the nozzle 3 into the orifice expansion pipe 4 is close to the atmospheric pressure.
Accordingly, when the high-pressure gas in the high-pressure tank 1 is squeezed from the high-pressure pipe 2 through the nozzle (throttle portion) 3 and then flows into the orifice expansion pipe 4, the cross-sectional area of the orifice expansion pipe 4. As the pressure suddenly expands, the pressure suddenly expands and the pressure drops rapidly. In this case, the operation in the orifice expansion pipe 4 has no adverse effect on the gas on the high-pressure pipe 2 side.
Accordingly, by taking a sufficient distance L and a sufficiently large inner diameter of the orifice expansion pipe 4 by the orifice expansion pipe 4, a normal temperature and low pressure flow is obtained, and the differential pressure from the normal pressure taps 6 and 7 is reduced to the pressure. The sensor 8 can be detected with high accuracy.

Specifically, the orifice expansion pipe 4 determines the inner diameter of the pipe and the distance L from the nozzle 3 so as to satisfy the normal use restriction of the orifice 5 by using the theoretical flow rate (predicted value). That is, it can be determined based on the following equation (1). Expected mass flow: m
m (kg / s) = Se · Ue · Ae (1)
Se = Outlet density (kg / m ³ )
Ue = exit speed (m / s)
Ae = Exit area (m ² )
The Se (outlet density) and Ue (outlet speed) are estimated from the pressure and temperature in the tank using an isentropic equation,
In the orifice expansion pipe 4, it is assumed that the pressure is atmospheric pressure, the temperature is the tank temperature, and the flow velocity Up (m / s) is
Up = m / Sp / Ap (2)
Sp = Gas density at atmospheric pressure (kg / m ³ )
Ap = Cross-sectional area of the orifice expansion pipe 4 (m ² )
Accordingly, the cross-sectional area Ap of the orifice expanding pipe 4, that is, the inner diameter of the orifice expanding pipe 4 is determined so that the flow velocity Up (m / s) of the orifice portion 5 in equation (2) satisfies the use restriction of the orifice 5.

  According to this embodiment, the expansion distance of the pressure from the nozzle 3 at the outlet of the high-pressure pipe of the orifice 5 is set so that the pressure of the gas ejected from the nozzle 3 into the orifice expansion pipe 4 is close to the atmospheric pressure. Therefore, the orifice 5 is supplied with gas that has dropped to near atmospheric pressure, and can be measured by the pressure sensor 8 that detects the pressure around the normal orifice 5, so that the pressure in the high-pressure tank 1 can be measured. Even when the change is large, the flow coefficient can be accurately measured. Therefore, a high-pressure gas flow measuring device that can accurately measure the flow rate of the high-pressure gas is obtained.

FIG. 2 is a block diagram of a hydrogen gas leak gas flow rate measuring apparatus showing a second embodiment of the present invention.
In FIG. 2, a large-diameter orifice expanding pipe 4 is embedded in the ground 14 laterally through a joint 10 in a vent stack 11 (exit end) opened to the atmosphere, and the outlet side is connected through a joint 10. It connects with the vent stack 11 (exit end) opened to the atmosphere.
A leak gas pipe 13 is connected to a hydrogen gas stored in a high-pressure hydrogen cylinder 12 on the inlet side of the orifice expansion pipe 4, and the leak hydrogen gas is injected into the orifice expansion pipe 4 through the leak gas pipe 13.

The orifice expansion pipe 4 is formed in a cylindrical body having a predetermined length with a cross-sectional area rapidly expanding from the leak gas pipe 13 as in the first embodiment.
Then, the cylindrical body, the proper position L ₀ from the inlet portion of the leak gas pipe 13, i.e. the leak gas pipe 13 located L ₀ as the pressure of the jet hydrogen gas becomes close to the atmospheric pressure in the orifice expansion tube 4 from The pressure tap 6 on the orifice 5 and the inlet side of the orifice 5 and the pressure tap 7 on the outlet side of the orifice 5 are installed, and a pressure sensor 8 detects a differential pressure from the pressure taps 6 and 7.

According to the second embodiment, the expansion distance L ₀ of the pressure from the inlet portion of the hydrogen gas leak gas pipe 13 accommodated in the high-pressure hydrogen cylinder 12 is set in the orifice expansion pipe 4 from the inlet portion of the leak gas pipe 13. Since the pressure of the jetted hydrogen gas is set at a position L ₀ so as to be close to the atmospheric pressure, the orifice 5 is supplied with the hydrogen gas lowered to the vicinity of the atmospheric pressure and affects the leak gas pipe 13 side. In addition, the differential pressure can be measured by the pressure sensor 8 that detects the pressure difference before and after the normal orifice 5, and the flow rate of the leaked hydrogen gas can be measured.

FIG. 3 is a block diagram of a high-pressure gas flow rate measuring apparatus equipped with a safety valve according to the third embodiment of the present invention.
In FIG. 3, when the high-pressure gas stored in the high-pressure tank 1 is sent to the outside through the high-pressure pipe 2, a safety valve 15 is provided in the middle of the high-pressure pipe 2, and the high-pressure pipe 2 at the outlet of the safety valve 15 has a large diameter. Are connected to the inlet 3 of the orifice expansion pipe 4.
The orifice expanding pipe 4 is provided with an orifice 5 at an appropriate position L from the inlet portion 3.
That is, as in the first embodiment, the orifice 5 is installed at a position L where the pressure of the gas injected from the inlet 3 into the orifice expansion pipe 4 through the safety valve 15 is close to the atmospheric pressure. A pressure tap 6 on the 5 inlet side and a pressure tap 7 on the outlet side of the orifice 5 are installed, and a differential pressure from the pressure taps 6 and 7 is detected by the pressure sensor 8.

  According to the third embodiment, the safety valve 15 is connected to the inlet portion 3 of the large-diameter orifice expanding pipe 4 downstream of the safety valve 15, and the distance of the orifice 5 from the inlet portion 3 through the safety valve 15 is the inlet portion 3. Since the position L is set so that the pressure of the gas jetted into the orifice expansion pipe 4 is close to the atmospheric pressure, the operation of the safety valve 15 can be performed without being affected by the orifice expansion pipe 4. The flow rate can be measured without any problems.

  According to the present invention, by using a large-diameter orifice expansion pipe with an orifice, the flow coefficient can be accurately measured even when the pressure change in the high-pressure tank is large, and the flow rate of the high-pressure gas can be accurately measured. A high-pressure gas flow measuring device and a high-pressure gas flow measuring method can be provided.

1 is a configuration diagram of a flow rate measuring device for a high-pressure tank showing a first embodiment of the present invention. FIG. It is a block diagram of the leak gas flow measuring device of the hydrogen cylinder which shows 2nd Example of this invention. It is a block diagram of the high pressure gas flow measuring device provided with the safety valve which shows 3rd Example of this invention. It is the schematic of the apparatus which measures the flow volume of the high pressure gas sent out from the high pressure tank in which the high pressure gas was accommodated, (A) is the case where the pressure change in a high pressure tank is small, (B) is the pressure change in a high pressure tank. The case where it is remarkably large is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High pressure tank 2 High pressure piping 3 Nozzle 4 Orifice expansion pipe 5 Orifice 6, 7 Pressure tap 8 Pressure sensor 11 Vent stack 12 Hydrogen cylinder 13 Leak gas piping 14 Underground 15 Safety valve L Distance from nozzle

Claims (5)

In the high-pressure gas flow measuring device that measures the flow rate of the high-pressure gas when the high-pressure gas stored in the high-pressure tank is sent to the outside through the high-pressure pipe,
The outlet of the high-pressure pipe is connected to the inlet of a large-diameter orifice expanding pipe whose outlet end is opened to the atmosphere. The orifice expanding pipe is configured to adjust the pressure difference between the orifice and the front and back of the orifice at an appropriate position from the inlet. A differential pressure gauge for detection is provided, and the distance of the orifice from the outlet portion is set at a position where the pressure of the gas ejected from the outlet portion into the orifice expansion pipe is close to atmospheric pressure. High pressure gas flow measuring device.   The outlet portion of the high-pressure pipe is configured as a predetermined throttle portion, and the orifice expanding pipe is formed in a cylindrical body having a predetermined length with the cross-sectional area rapidly expanding from the throttle portion, and the orifice and The high-pressure gas flow rate measuring device according to claim 1, further comprising a differential pressure gauge. A high-pressure gas flow measurement method for measuring a flow rate of the high-pressure gas when the high-pressure gas stored in the high-pressure tank is sent to the outside through a high-pressure pipe,
A large-diameter orifice expansion pipe is connected to the outlet of the high-pressure pipe, and the orifice is set at a position where the pressure of the gas injected into the orifice expansion pipe is close to atmospheric pressure. A high-pressure gas flow rate measuring method characterized by detecting a differential pressure. In the high-pressure gas flow measuring device that measures the flow rate of hydrogen gas when the hydrogen gas stored in the high-pressure hydrogen cylinder is sent to the outside through the leak gas pipe,
A large-diameter orifice expanding pipe whose outlet end is open to the atmosphere is buried in the ground, and the outlet portion of the leak gas pipe is buried in the ground and connected to the inlet of the orifice expanding pipe. A differential pressure gauge for detecting the pressure difference between the orifice and the front and back of the orifice is provided at an appropriate position from the inlet, and the distance of the orifice from the outlet of the leak gas pipe is the hydrogen jetted into the orifice expansion pipe from the outlet. A high-pressure gas flow rate measuring apparatus, wherein the gas pressure is set at a position close to atmospheric pressure. In the high-pressure gas flow measuring device that measures the flow rate of the high-pressure gas when the high-pressure gas stored in the high-pressure tank is sent to the outside through the high-pressure pipe,
A safety valve is provided in the middle of the high-pressure pipe, and the high-pressure pipe at the outlet of the safety valve is connected to an inlet of a large-diameter orifice expanding pipe. The orifice expanding pipe is positioned at an appropriate position from the inlet and the pressure before and after the orifice. A differential pressure gauge for detecting the difference is provided, and the distance from the outlet portion of the orifice is set to a position where the pressure of the gas ejected from the inlet portion into the orifice expansion pipe through the safety valve is close to the atmospheric pressure. This is a high-pressure gas flow rate measuring device.

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