JPS61124823A - Detector of electromagnetic flowmeter - Google Patents

Abstract

PURPOSE:To enhance not only the strength to the high temp. and high pressure of a measuring fluid or the load at the time of mounting but also accuracy, by making the length of a metal outer cylinder in the axial direction thereof shorter than that of a ceramic conduit in the axial direction thereof and largely chamfering the outer peripheral part of the conduit. CONSTITUTION:An exciting coil 5 is provided to the periphery of a ceramic conduit 1c to generate a magnetic field in a direction crossing the axial direction of the conduit 1c at right angles and a pair of electrodes 3 are arranged in opposed relation to each other to supply a current crossing both of the axial direction of the conduit 1c and the magnetic field at right angles. A metal outer cylinder 7c shorter than the length of the ceramic conduit 1c in the axial direction thereof is attached to the outer periphery of the exciting coil 5 to fix the same. Further, both sides of the ceramic conduit 1c in the axial direction thereof are largely chamfered at an angle theta to reduce the contact surface with piping as small as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electromagnetic flowmeter detector, and more particularly to a seven-layer shape of a ceramic conduit and a pipe joining means suitable for measuring flow rates in high temperature, high pressure piping lines.

[Background of the invention]

Figure 1 is a structural diagram of a conventional electromagnetic flowmeter detector.
FIG. 2 is a sectional view taken along the line A--A in FIG. 1.

In FIG. 1 and FIG. 2, 1 is a conduit through which the measurement fluid passes;
2 is an insulating lining that electrically insulates the inner surface of the conduit; 3
・3a and 3b are electrodes that detect the flow rate signal, 4, 4a, 4
b is an insulating spacer, 5, 5a, and 5b are excitation coils that create a magnetic field, 6 is an iron core, 7 is an outer cylinder that houses a magnetic circuit, and 8.
8a and 8b are signal lead wires for transmitting the flow rate signal detected by the electrodes to the outside, 9 is an earth ring for grounding the measured fluid, and 10 is a short circuit line that connects the earth ring and the outer cylinder, and these are integrated. This forms an electromagnetic flow meter detector that measures the flow rate. With conventional electromagnetic flowmeter detectors, the fluid to be measured is, for example, (1) continuously operated at a high temperature of 160°C or higher;
2) When operated under heat cycles between room temperature and high temperatures of 160°C or higher, the commonly used tetrafluoroethylene resin lining causes bubble-like deformation on the lining surface, causing a change in the actual inner diameter. However, there was a drawback that the measurement error increased and the operation could no longer be continued.

For this reason, the conduit and lining are integrally molded using ceramics (including glass, refractory bricks, ceramics, etc.) that are heat-processed from non-metallic inorganic raw materials that have excellent heat resistance, insulation properties, and corrosion resistance. structure was adopted. However, in the former case, since the O-ring 11t is used to relieve the stress at the joint between the outer cylinder 7 and the ceramic conduit 1a, the measured fluid rises at the O-ring lit, which reduces the corrosion resistance of the detector and the temperature of the measured fluid. had the disadvantage of being limited by the O-ring material. In addition, in the latter case, the outer cylinder 7 and the ceramic conduit 1b are connected by shrink-fitting as much as possible so as not to come into contact with the entire outer cylinder, and a compound is applied to make the connection between the outer cylinder 7 and the ceramic conduit 1b. ) The tightening necessary to prevent leakage of the measured fluid when attached to the piping is stress concentration due to the load. (2) Stress caused by the difference in thermal expansion coefficient in the pipe axis direction of the conduit and outer cylinder due to the high temperature of the measured fluid. There was a drawback that concentration etc. occurred and damage such as cracks occurred. □ [Object of the Invention] It is an object of the invention to provide a highly accurate electromagnetic flowmeter detector that has sufficient strength even under the conditions.

[Summary of the invention]

The outline of the present invention is that ceramics, which are generally known as non-metallic inorganic materials, and steel, which is a structural material, have a coefficient of thermal expansion of [x 1
01/C], focusing on the fact that the latter has larger deformation, the length of the ceramic conduit in the axial direction,
In terms of the axial length of the steel outer tube, the outer tube is made shorter in advance, and the outer circumference of the conduit is made larger to minimize the load required for tightening to prevent leakage of the measured fluid. By minimizing the contact surface with the pipe and the pipe, the thermal and mechanical stress concentration that occurs at the joint between the pipe and the outer cylinder can be minimized and ignored when used in lines under high temperature and high pressure. This realizes an electromagnetic flowmeter detector.

[Embodiments of the invention]

An embodiment of the present invention is shown in FIGS. 5 to 7 below. In FIG. Torishi is the best. Reference numeral 4' denotes an insulating spacer having a heat-insulating effect, which determines the mounting dimensions of the conduit IC and the excitation coil 5, and also blocks direct heat transfer from the fluid to be measured. 7C is
In the outer cylinder of the present invention, the length of the outer cylinder in the tube axis direction is made as short as possible compared to the length of the conduit IC in the tube axis direction. The connecting portion between the ceramic conduit IC and the outer cylinder 7C is generally heat-fitted, and a compound for waterproofing the magnetic circuit storage portion is embedded in the gap. Here, conduit IC and outer cylinder 7
The following stresses occur at the joints of C: &:l:.

(1) Thermal stress caused by the temperature difference between the temperature at which the conduit is heated by the high temperature fluid to be measured and the temperature of the outer cylinder in the atmosphere, (2) Leakage of the fluid to be measured when attached to the piping. The axial tightening required to prevent this is due to the mechanical stress generated by the load.

Here, the typical properties of ceramics and steel are shown in the table below.

The stress in term (1) is caused by the difference in thermal expansion coefficients of different materials, and the elongation of a rod due to heat is generally expressed by equation (1).

L * = (αt+1)to ・・・−・・・・・・(
1) Here, α: Coefficient of thermal expansion t: Difference between initial concentration and final temperature 4 = Original length at initial temperature tt: Length after deformation at final temperature The above equation (1) is used for a ceramic conduit. Next, when adding a dash to the steel of the outer cylinder, the elongation of the outer cylinder is
The formula (2) is obtained.

tt=(α' t +1)to ・・・・・・・・・
(2) By taking the ratio of these amounts of deformation to find the strain at the joint between the two, and substituting it into equation (8), although it is a simplified formula, the stress can be found.

σ= g E ・・・・・・・・・O・・・・
...(8) Here, σ: Thermal stress value: Strain: E: Elastic coefficient. Therefore, when connecting parts are made of different materials with thermal expansion coefficients α or αI that differ by K1 order of magnitude, the coefficient of By reducing the original length or volume of the larger one, the generation of thermal stress can be minimized. Therefore, when comparing the lengths in the axial direction of the tubes as shown in FIG. 5, it can be seen that the structure should be such that the conduit > the outer cylinder.

The stress in item (2) is the mechanical stress caused by the load on the pipe when heavy equipment is attached to the pipe, and the tightening in the pipe axis direction required to prevent leakage of the measured fluid.

The tightening load applied to the conduit flare part in use is JI.
8B8243 Structural Annex 2 of Pressure Vessel Stress Calculation Method (shown in equation 4).

W-t=G"P+-'-gbGmP""(4
)ζWhere, W,, : Required minimum bolt load in operating condition G : Diameter of gasket Q at the position where reaction force is applied P : Maximum operating pressure b = Effective width of gasket m : Gasket coefficient The first term is the minimum required load, but the second term, the effective width of the gasket 120 in the radial direction, can be achieved by greatly chamfering the outer circumference of the conduit at an angle θ as shown in FIG. The tightening load can be reduced to 1/2 of that of the conventional method, the tightening load can be minimized, and the generated stress itself can be reduced.

Compared to the conventional stress generated in (1) and (2) mentioned above,
FIG. 5 shows an electromagnetic flowmeter detector having a shape that can be minimized at the same time.

Next, in FIG. 6, the second term on the right side of the above equation (4) is further reduced, and at least one concave groove is provided in the flare part of the ceramic conduit 1d, and the gap between the earth ring 9 and the conduit 16 is To prevent liquid leakage between the earth ring 9 and the piping flange flare part, an O-ring with excellent corrosion resistance is used for the sealing gasket tab of the 1 cell 7. When this self-sealing gasket is used, the gasket coefficient m in the second term on the right-hand side of equation (4) becomes 0), W is the tightening load in the first term on the right-hand side, and the stress generated in the connection part. can be minimized.

In FIG. 7, the ground ring 9 shown in FIG. 6 is deposited directly on the conduit. In this case, in order to make the surface area sI of the ground ring 9 in contact with the liquid by vapor deposition, the inner circumference of the conduit is chamfered at an angle θ to S! The wetted surface area (St
``St).

In addition, the terminal for extracting the ground potential of the liquid from the conduit 1e on which the earth ring is vapor-deposited is directly buried in the conduit through the embedded screw terminal 13t, and is integrally vapor-deposited with the earth ring formed by vapor deposition, or alternatively, is press-fitted. Fixed. As a result, the volume of the expensive corrosion-resistant material can be minimized, and an inexpensive electromagnetic flowmeter detector with a simple structure can be obtained.

In other embodiments of the present invention, the chamfer at the angle θ on the outer periphery of the ceramic conduit shown in FIGS. , the same effect can also be obtained by using a curved surface that is concave on the inside.

In addition, although the chamfered angle θ of the vapor-deposited ame sling for fluid grounding provided on the inner circumference of the conduit is shown flat,
A similar effect can be obtained by using a curved surface that is convex inward in the radial direction.

〔Effect of the invention〕

According to the present invention, an electromagnetic flowmeter is used to measure the flow rate of piping in which the fluid to be measured flows at high temperature and high pressure, and the tightening at the time of any piping installation reduces thermal and mechanical stress even under load. Since we can create an electromagnetic flowmeter detector with an extremely small and negligible structure, it can fully demonstrate the corrosion resistance of ceramics even when used in high-temperature and high-pressure lines, has sufficient mechanical strength, and has minimal dimensional changes in the inner diameter of the pipe. This has the effect of obtaining an inexpensive and highly accurate electromagnetic flowmeter.

Furthermore, if you use an embedded fluid grounding potential extraction terminal with a vapor-deposited grounding ring that secures the liquid contact surface area necessary for grounding, but the rest is extremely small, it will be very clear, vertical, and
A low cost effect can be obtained.

[Brief explanation of drawings]

Figure 1 is a structural diagram of an electromagnetic flowmeter according to the prior art, Figure 2 is a sectional view taken along line A-A in Figure 1, Figures 3 and 4 are structural diagrams of the prior art, Figure 5, 6 and 7 are structural diagrams showing embodiments of the present invention. 1... Conduit, 2... Insulating lining, 3.3a.
-3b... Electrode, 4, 4a, 4b... Insulating spacer, 5, 5m, 5b... Excitation coil, 6... Iron core, 7
...Outer cylinder, 8, 8a, 8b...Signal leader line, 9...
- Earth ring, 10... Short circuit wire, 11... 0 ring, 12... Gasket, IC, 1d, 1e... Ceramic conduit of the present invention, 4'... Heat resistant insulating spacer, 7c. ...Outer cylinder of the present invention, 9'... Vapor deposited earth ring, 13... Embedded fluid grounding potential extraction terminal, 14.
...Spring action No. 30 Fig. 4 No. 5 No. 65a Pigeon 7f21

Claims (1)

[Claims] 1. A conduit through which a fluid to be measured is passed, an excitation coil that applies a magnetic field in the radial direction of the conduit, a pair of electrodes provided on the conduit surface perpendicular to the direction of the magnetic field and the axial direction of the conduit, and the whole. In an electromagnetic flow meter detector consisting of an earth ring that grounds the fluid in the outer cylinder, the length of the ceramic conduit and the metal outer cylinder in the axial direction of the pipe is as short as possible compared to the conduit. An electromagnetic flowmeter detector characterized in that the outer peripheral end of the flared portion of the conduit is largely chamfered so that the end of the outer tube in the tube axis direction does not come into contact with the pipe joint surface. 2. The electromagnetic flowmeter detection according to claim 1, characterized in that it has a structure in which at least one recess is provided in the flared surface to prevent leakage of the measured fluid through a self-seal gasket. vessel. 3. In claim 1, a fluid ground potential extraction terminal is embedded in the outer peripheral slope of the conduit flare part and the inner and outer peripheral slope parts and the side surfaces are integrally formed by vapor-depositing a corrosion-resistant metal film equivalent to an earth ring. An electromagnetic flowmeter detector characterized by: