JPS5975118A - Electromagnetic flowmeter - Google Patents

Abstract

PURPOSE:To make an exchange of a measuring electrode easy and to measure the flow rate of a high temp. and high pressure fluid by forming the measuring electrode of a liningless electromagnetic flowmeter in one body with ceramic and by providing the measuring electrode to a pipe body by a screw means. CONSTITUTION:The measuring electrode 3 is formed in one body with the ceramic covering the circumference. The electrode 3 is made to one body with a metal bush 8 fitted with screw to the pipe body 2 through the ceramic 7. Otherwise, the electrode 3 is pressed by a pressing screw 10 through the ceramic 7. Thereby, the electrode 3 can be removed and exchanged easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic flowmeter, and particularly to an improvement in the electrode portion of an electromagnetic flowmeter without a lining (a liningless electromagnetic flowmeter).

Recently, an electromagnetic flowmeter has been announced that does not require a lining to insulate the inner surface of the conduit.

Prior to explaining the present invention, this conventional example will be explained below.

In FIG. 1, a non-magnetic and electrically conductive tube body 2 through which a fluid to be measured 1 whose flow rate is to be measured flows is provided with measurement electrodes 3, 3a at positions orthogonal to a magnetic field B. As shown in FIG. Furthermore, measurement electrode 3
．． 3af, ring-shaped power supply terminals 4 and 4a are provided surrounding it.

The measurement electrodes 3, 3a are attached to the tube body 2 via an insulating material 6 such as epoxy resin. Amplifiers 5 and 5a whose gains are set to 1 by feedback supply the induced voltages detected by measurement electrodes 3 and 3a to power supply terminals 4 and 4a, respectively. Therefore, the power supply terminals 4° 4a have the same potential as the measurement electrodes 3 and 3a, and a large current flows between them, causing the tube body 2
A potential drop occurs. If the wall thickness of the tube body 2 is uniform, the potential distribution between the power supply terminals 4 and 4a will be linear with respect to the length of the tube's inner circumference. It is known that the distribution of the induced voltage near the inner wall of the pipe of the fluid 1 is sinusoidal over the inner circumference when the magnetic field B is uniform regardless of the location and the flow is uniform across the cross section of the pipe 1. ing. Therefore, if the positions of the power supply terminals 4 and 4a are appropriately selected, the potential distribution on the tube wall and the distribution of induced voltage in the fluid to be measured 1 can be approximated at all points on the inner circumference of the tube body 2. I can do it.

Therefore, even if the inner wall of the tube body 2 is conductive, there is no current flowing between the tube body 2 and the fluid to be measured 1, so the measurement electrodes 3, 3a
Therefore, the voltage obtained from the terminals 6, 6a via the take-out amplifiers 5, 5a is the same induced voltage as in the case with a normal lining.If the lining to provide insulation to the inner wall of the pipe is no longer necessary, the lining Troubles such as deformation and damage can be prevented and the reliability of the electromagnetic flowmeter can be improved. Furthermore, since a thermally sensitive lining is not required, there have been expectations that high temperature fluids can be measured.

However, in the conventional technique shown in FIG. 1, since the insulating material 6 made of a polymeric material such as epoxy resin is used, it is not possible to actually measure high-temperature fluids. This is due to the low heat resistance temperature of polymer materials (e.g. 80% for epoxy resins).
℃). For this reason, although a liningless electromagnetic flowmeter that did not require a lining was developed, the insulating material 6 became a bottleneck that made it impossible to measure high-temperature fluids, and the advantages of the liningless electromagnetic flowmeter could not be fully exploited. It wasn't. Furthermore, since the measuring electrodes 3, 3a are fixed to the insulating material 6, even if the liquid contact surfaces of the measuring electrodes 3, 3a become dirty, the measuring electrodes 3, 3a cannot be replaced. Therefore, accurate flow rate measurement may be hindered due to contamination of the liquid contact surface.

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, an object of the present invention is to provide an electromagnetic flowmeter that can measure high-temperature fluids and replace measuring electrodes. The technical idea of the present invention, which achieves this object, is that the measurement electrode of a liningless electromagnetic flowmeter is formed integrally with ceramic, and the measurement electrode is attached to the pipe body by screwing means. .

Embodiments of the present invention will be described in detail below based on the drawings. Note that parts that are the same as those in the prior art are given the same numbers and redundant explanations will be omitted.

FIG. 2 shows a first embodiment of the invention. In the figure, 3 is a measurement electrode, 7 is a ceramic, and an 8Fi metal bushing, and these three are fired as one unit. Since the metal bushing 8 is screwed onto the tube body 2, the measuring chamber 1 pole 3 integrated with the metal bushing 8 can be easily removed and replaced. A hollow metallic O-ring 9, which is not easily deformed by pressure, is interposed between the metal bush 8 and the tube body 2. Moreover, the measurement electrode 3
Since the ceramic 7 has a tapered flange whose width gradually increases in the radial direction of the tubular body 2, the flange does not protrude toward the outer circumference. Therefore, the effects of the collar and the hollow O-ring 9 work together, making it possible to measure high-pressure fluid of about 1000 krf/ca. Furthermore, measurement electrode 3
Since the ceramic 7 that insulates the sensor is resistant to heat, it is possible to measure fluids at a high temperature of about 500°C. Of course, since this embodiment does not have a lining, it is equipped with a power supply means (not shown) for supplying current to the tube body 1, as in the embodiment shown in FIG. A large induced electromotive force is generated in the fluid. In addition, the second
Although not shown in the drawings, the third embodiment also includes a power supply means and the like.

FIG. 3 shows a second embodiment of the present invention, in which the measurement electrode 3 is a capacitance detection type electrode that does not come into contact with the fluid 1 to be measured. Note that the configuration and operation of other parts are the same as the embodiment shown in FIG.

FIG. 4 shows a third embodiment of the invention.

In this embodiment, the measuring electrode 3 is fired integrally with the ceramic 7. A push screw 1o is screwed into the tube body 2 and presses the ceramic 7 downward in the figure, thereby attaching the measurement electrode 3 integrated with the ceramic 7 to the tube body 2. Also, the measurement electrode 3 is easy to replace,
It is also possible to measure high temperature and high pressure fluids.

As specifically explained above in conjunction with the embodiments, according to the present invention, it is possible to provide an electromagnetic flowmeter that allows easy replacement of measurement electrodes and is capable of measuring high-temperature and high-pressure fluids.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional liningless electromagnetic flowmeter, and FIGS. 2 to 4 are sectional views showing exemplary embodiments of the present invention. In the drawings, 1 is a fluid to be measured, 2 is a tube body, 3.3a is a measurement electrode, 7 is a ceramic, 8 is a metal bushing, 9 is a hollow metal O-ring, and 10 is a set screw. Patent applicant Hokushin Electric Manufacturing Co., Ltd. Patent attorney Shibu Mitsuishi (and 1 other person)

Claims (2)

[Claims] (1) A conductive tube for flowing the fluid to be measured, a magnetic field generating means for applying a magnetic field to the tube, and the tube for extracting the induced electromotive force generated in the fluid to be measured. In an electromagnetic flowmeter, the electromagnetic flowmeter is equipped with a measuring electrode that is insulated and provided, and a power supply means that forms a potential distribution in the pipe body that is approximately equal to the induced electromotive force at least near the measuring electrode, the measuring electrode is The measuring electrode is formed integrally with the surrounding ceramic, and the measuring electrode is either integrated with the screwing means screwed onto the tube through the ceramic, or is pressed by the screwing means through the ceramic. An electromagnetic flow needle, characterized in that the tube body is provided with an electromagnetic flow needle. (2) At least one of the measurement electrode and the ceramic,
The electromagnetic flowmeter according to claim 1, characterized in that the tube body has a flange portion in which the diameter of the inner circumference side portion is larger than the diameter of the outer circumference side portion in the radial direction of the pipe body.