JPS61193042A - Differential pressure gauge - Google Patents

Abstract

PURPOSE:To measure even small differential pressure with high precision without being affected by the temperature of conductive fluid by measuring the differential pressure of the conductive fluid by utilizing electromagnetically induced force. CONSTITUTION:A communication pipe 6 is provided between the upstream-side high-pressure part 2a and downstream-side low-pressure part 2b of an orifice 2 and an electromagnetic flow meter and an electromagnetic brake 9 are interposed. When the fluid flows in the pipe 1, a pressure difference is generated across the orifice 2 and part of the fluid is diverted into the communication pipe 6. The velocity and rate of the diverted fluid are detected by the flow meter 7, whose signal is sent from an indication part 8 to a device 10. Then, the electromagnetic brake 9 is expected to intercept the flow of the fluid with the current sent through the device 10. Its braking force is proportional to the current supplied to the electromagnetic brake 9, so the current value is varied and read while the flow in the communication pipe is measured by the flow meter, and then the current in proportional to the braking force and the braking force is proportional to the differential pressure, which is found from the current value.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a differential pressure needle that measures the differential pressure between two locations of a fluid flowing in a pipe, and in particular, it relates to a differential pressure needle that measures the differential pressure between two locations of a fluid flowing in a pipe.
It is suitable for other conductive fluids.

[Prior Art and Problems] As means for measuring the flow rate or flow rate of fluid, there are a method using a pitot tube, etc., a method using a pressure difference before and after an orifice, and the like.

In methods using pitot tubes, etc., when the flow velocity is about 201/sec, the differential pressure generated in the pitot tube is small, about 2 cranes in the water column, so when the flow velocity is small, the error rate increases and the accuracy is poor. .

What is shown in FIG. 4 is a flow needle using a conventional orifice. A fluid to be measured flows in a pipe 1, and an orifice 2 is provided, and the flow rate is calculated by measuring the pressure difference that occurs before and after the orifice.

High pressure side pressure conduit 3a led from the upstream side of orifice 2
A pressure difference detection unit 4 detects the pressure difference between the pressure conduit 3b and the low pressure side pressure conduit 3b led from the downstream side, displays this on a pressure difference indicator 5, and calculates the flow rate from this pressure difference. be. A diaphragm displacement type, a bellows displacement type, or the like is used for the differential pressure detection unit 4, but for example, fluids such as liquid metal are high temperature and dangerous, so it is necessary to avoid damage or leakage. Since the pressure receiving parts such as the diaphragm and bellows must be made with high rigidity, the differential pressure detection sensitivity becomes poor, and it is difficult to measure differential pressures of less than a few millimeters of water column with sufficient accuracy. I can't.

[Object of the Invention] Therefore, an object of the present invention is to provide a differential pressure needle that is not affected by the temperature of the fluid to be measured and can accurately measure even a small differential pressure.

[Solution Means] In order to achieve this object, the present invention provides a differential pressure gauge that measures the differential pressure between two locations in a conduit through which a conductive fluid flows.
A communication pipe provided to communicate the two locations, a flow rate needle that measures the flow rate of the fluid flowing within the communication pipe, an electromagnetic brake that brakes the flow of the fluid flowing within the communication pipe, and the electromagnetic brake. The invention is characterized in that it is equipped with an ammeter that measures the current supplied to the device.

[Function] Since the present invention has the above configuration, if there is a pressure difference between two locations to be measured, a flow corresponding to the pressure difference is generated in the communication pipe provided to communicate the two locations. Electric current is supplied to the electromagnetic brake so as to brake the flow within this communication pipe. The braking force is proportional to the current supplied to the electromagnetic brake, so if you change the current value while measuring the flow in the communication pipe with a flowmeter and read the current value with an ammeter, the current will be proportional to the braking force. Since the braking force is proportional to the differential pressure, the differential pressure can be determined from the current value.

[Example code] The present invention will be described below with reference to the illustrated embodiments.

1 to 3 show embodiments of the invention. This example is an example of differential pressure measurement of an orifice flow needle. In FIG. 1, an orifice 2 is provided in a fluid flow path flowing inside a pipe 1, and the flow rate is measured by measuring the pressure difference between the front and rear sides. In order to determine the differential pressure, a communication pipe 6 is provided so as to communicate between the upstream high pressure section 2a and the downstream low pressure section 2b of the orifice 2.

An electromagnetic flowmeter 7 and an electromagnetic brake 9 are interposed in the communication pipe 6.

The basic structure of the electromagnetic flowmeter 7 is shown in FIG. The permanent magnet 14 is installed so that a magnetic field is generated in a direction perpendicular to the fluid flow direction in the communication tube 6 (the axial direction of the communication tube 6), and both the axis of the communication tube 6 and the magnetic field of the permanent magnet 14 are generated. A potential difference detection electrode 13a that detects a potential difference in the fluid in a direction perpendicular to the direction.

13b is provided and connected so that the electromagnetic flowmeter detection section 8 can read the potential difference between the potential difference detection electrodes 13a and 13b. This takes advantage of the fact that when a conductive object moves to break the magnetic flux, a voltage proportional to the speed of the movement is generated.

The basic structure of the electromagnetic brake 9 is as shown in FIG.
A permanent magnet 16 is installed to create a magnetic field in a direction perpendicular to the axis of the communication tube 6, and a current supply bus bar 158.15 is installed so that a current flows in the fluid in a direction perpendicular to both the axis of the communication tube 6 and the magnetic field. 'b is provided, and current is supplied from the DC power supply 12. This is based on Faraday's left-hand rule, which states that when a current flows through a magnetic flux, an electromagnetic force is generated in a direction perpendicular to it.

In FIG. 1, a power adjustment device 10 is provided in the current supply path from the DC type #+12 to the electromagnetic brake 9.
It is controlled by a signal from an electromagnetic flowmeter 7. Further, an ammeter 11 for measuring the current supplied to the electromagnetic brake 9 is provided.

When fluid flows through the tube 1, a pressure difference is created across the orifice 2. Due to this pressure difference, a part of the fluid flows in the communication pipe 6 in a divided manner. The larger the pressure difference, the faster the flow of the diverted fluid. The flow velocity or flow rate of the diverted fluid is detected by the electromagnetic flow meter detection section 7, and the signal is sent from the indicator section 8 to the power adjustment device IO. The electromagnetic brake 9 attempts to stop the flow of fluid by the electric current sent via the power regulating device 10 according to the principle described above.

If the flow in the communication pipe 6 is dammed, the force F required for the damming is given by A, the cross-sectional area of the flow in the communication pipe 6 at the damming point, Pl, the pressure on the high pressure side 2a, and P2, the pressure on the low pressure side 2b. Then, F=A (Pl-P2)
・・・・・・ +11. That is, the force F that blocks the flow is proportional to the differential pressure (Pl-P2).

On the other hand, the electromagnetic brake FB has the following formula: FB=B + d (2 ).

Therefore, if current is supplied to the electromagnetic brake 9 so that the flow in the communication pipe 6 becomes zero, then the fluid force F and the damming force FB are balanced, and F=FB. , A (PI - P2) = Bld...
(3) Also, since A−πd2/4, (Pl −P2 )=4B I/πd ・・・・・・
(4) becomes. In order to make this equation hold, flowmeter 7
The signal from the electromagnetic brake 9 may be input into the power adjustment device 10 to automatically adjust the current supplied to the electromagnetic brake 9 so that the flow rate becomes zero.

In equation (4), if the magnetic flux density B and the tube diameter d are set, the differential pressure (PL - P2) will be proportional to the current l, and if the current 1 is measured by the ammeter 11, the differential pressure (
PI-P2) can be calculated.

Note that when measuring a small differential pressure, the current I can be increased by decreasing the magnetic flux density or increasing the inner diameter d of the tube, which is convenient for the micro differential pressure meter /1111.

Additionally, differential pressure gauges are generally affected by temperature, but this differential pressure gauge uses electromagnetic force, so it is not affected by temperature.

In this embodiment, the flowmeter 7 is an electromagnetic flowmeter, but other types of flowmeters may be used.

[Effects of the Invention] As explained above, according to the present invention, the differential pressure of liquid metal or other conductive fluid is measured using electromagnetic induction force, so it may not be affected by temperature. It will not become impossible to measure. Further, even if the differential pressure is small, the current value can be increased by reducing the magnetic flux density, so it can be measured with high accuracy. Furthermore, since there are no moving parts as a mechanism, there are no fragile parts and there is no risk of breakage or leakage, making it particularly suitable for use with dangerous fluids.

[Brief explanation of the drawing]

Fig. 1 is a detailed explanatory diagram of this invention, Fig. 2 is an explanatory diagram of an electromagnetic flowmeter, and Fig. 3 is an explanatory diagram of the electromagnetic brake 65i! Mingzu, No. 4
The figure is an explanatory diagram of a conventional differential pressure needle. In the figure, 6 is a communication pipe, 7 is an electromagnetic flowmeter detection part, 8 is an electromagnetic flow needle indicator, 9 is an electromagnetic brake, 10 is a power regulator, 11 is an ammeter, 12 is a DC power supply, and 13 is a potential difference detection electrode. , 15 is a current supply bus bar, and 14.16 is a permanent magnet. Sub-agent Patent Attorney Yukio Harada

Claims (1)

[Claims] A differential pressure gauge that measures the differential pressure between two locations in a conduit through which a conductive fluid flows, includes a communication pipe provided to communicate the two locations, and a flowmeter that measures the flow rate of the fluid flowing within the communication pipe. A differential pressure gauge comprising: an electromagnetic brake that brakes the flow of the fluid flowing through the communication pipe; and an ammeter that measures the current supplied to the electromagnetic brake.