JPH10221137A - Jig for fitting probe of cryogenic ultrasonic flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a jig for fitting a probe of a cryogenic ultrasonic flowmeter whereby the contact between the probe and a pipe is maintained constant both at a cryogenic temperature environment and at a normal temperature environment, so that ultrasonic waves can be propagated stably and a flow rate can be measured stably. SOLUTION: A probe-fitting jig 16 supports an ultrasonic probe 14 and is provided with a ring-shaped frame 20 which is formed of a schematically inverted U-shape upper frame 18 and a rightly inverted U-shaped lower frame 19 coupled with the upper flame. A gap between an end part 18b of the upper frame 18 and an end part 19b of the lower frame 19 is extensible and compressible by a spring 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe mounting jig for a clamp-on type ultrasonic flowmeter for measuring a flow rate of a cryogenic fluid flowing in a pipe.

[0002]

2. Description of the Related Art A conventional jig for mounting an ultrasonic flowmeter probe for cryogenic temperature is shown in FIG. The clamp-on type ultrasonic flow meter has a pair of ultrasonic probes 42, 42 attached to predetermined positions on the outer wall surface of the tube 40, and radiates ultrasonic waves to the fluid in the tube via the tube wall. The flow rate and the flow rate are obtained by measuring the propagation time. In order to mount the ultrasonic probes 42, 42, a conventional probe mounting jig 46 has a housing 44 for accommodating the ultrasonic probe 42 made of a metal. The structure is such that the ultrasonic probe 42 is pressed against the tube 40 with a screw 50 passing through the center of the housing 44 and fixed to the tube 40 with a band 48.

[0003]

However, in an extremely low-temperature environment, the water penetrating between the band and the pipe or the water in the air freezes to generate a force in the band to extend the band. However, there is a problem that the band is plastically deformed and elongates with the passage of time. Further, after that, once the tube has returned to normal temperature and the ice has melted, a gap is formed between the band and the tube, and as a result, the jig and the ultrasonic probe float up from the tube, and the propagation of ultrasonic waves, and There is a problem that the flow measurement is hindered.

[0004] Further, since heat is transmitted from a contact portion between the band and the pipe, a liquefied gas in the pipe may be vaporized, resulting in a problem of economical loss. Further, there is another problem that the tension applied to the band portion when the probe mounting jig is fixed to the tube is blocked by the friction of the tube surface, and does not become an effective probe pressing force.

The present invention has been made in view of such a problem, and the inventions of claims 1 to 3 maintain constant contact between the ultrasonic probe and the tube both in an extremely low temperature environment and in a normal temperature environment. It is an object of the present invention to provide a cryogenic ultrasonic flowmeter probe mounting jig capable of performing stable ultrasonic wave propagation and flow rate measurement by maintaining the temperature. It is another object of the present invention to provide a cryogenic ultrasonic flowmeter probe mounting jig which can reduce the propagation of heat to and from a pipe in addition to the above objects.

[0006] In addition to the above object, the invention according to claim 3 further reduces the influence of friction on the tube surface and generates an effective probe pressing force. An object is to provide a mounting jig.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, an ultrasonic wave is emitted to a cryogenic fluid flowing in a pipe to measure the flow rate of the fluid. A cryogenic ultrasonic flowmeter probe mounting jig for attaching an ultrasonic probe to an outer wall surface of a pipe, which supports the ultrasonic probe and is fixed to the pipe by tightening the outer periphery of the pipe. An annular frame is provided, and a part of the annular frame is provided with an extendable mechanism.

When the water or air in the air permeating between the pipes of the annular frame freezes, the expandable and contractible mechanism provided on the annular frame expands, and when the ice melts by returning to normal temperature or the like. As the telescopic mechanism contracts, the annular frame always keeps the outer periphery of the tube clamped, thus maintaining constant contact between the ultrasonic probe and the tube.

According to a second aspect of the present invention, in the first aspect, the portion of the annular frame that contacts the outer wall surface of the pipe is made of a heat insulating material. By using a heat insulating material for the contact portion with the tube, the propagation of heat between the tube and the probe mounting jig is reduced. Although the annular frame can entirely contact the outer periphery of the tube to tighten the tube, the invention according to claim 3 is the invention according to claim 1 or claim 2, wherein the annular frame is And a contact body protruding in the inner diameter direction at appropriate intervals in the circumferential direction, and the contact body is in line contact with the outer wall surface of the tube.

[0010] Since the entire annular frame does not contact the pipe but contacts the pipe via the contact body, the contact area is reduced.
Therefore, the influence of friction on the tube surface is reduced, and the tightening force of the annular frame is effectively transmitted to the pressing force of the ultrasonic probe against the tube. In addition, the propagation of heat between the tube and the probe mounting jig is reduced.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view showing an embodiment of a cryogenic ultrasonic flowmeter probe mounting jig according to the present invention, FIG. 2 is a sectional view taken along line 2-2 in FIG. 3, and FIG. It is the figure seen from the arrow line of sight 3 directions. In the figure, reference numeral 10 denotes a tube, and the inside of the tube 10 is a measuring fluid, for example, L
Cryogenic fluid such as NG or liquid nitrogen is flowing. Tube 1
0, two ultrasonic probes 14 respectively holding ultrasonic oscillators 12 for transmission and reception are attached by a probe attachment jig 16 so as to face each other with a tube interposed therebetween. The method constitutes an ultrasonic flowmeter.
However, the arrangement of the ultrasonic probe 14 can adopt an arbitrary arrangement such as the V method.

The probe mounting jig 16 has an annular frame 20 formed by connecting an upper frame 18 having a substantially inverted U shape and a lower frame 19 having a substantially U shape. The annular frame 20 is fixed to the tube 10 by tightening the outer periphery of the tube 10. Further, two annular frames 20 are provided at intervals in the longitudinal direction of the pipe 10, and each annular frame 20 is provided with a plurality of rails 21 extending between the upper frames 18 and between the lower frames 19. Are connected via

As shown in FIG. 2, one end 18a of the upper frame 18 and one end 19 of the lower frame 19 are provided.
a is provided with mounting bodies 24 and 25 fitted in long holes provided in the respective ends 18a and 19a.
6 and the nut 27 fixed to the mounting body 25
4, 25 are sandwiched. Also, the other end 18b of the upper frame 18 and the other end 1 of the lower frame 19
9b is also provided with mounting bodies 24 and 25 fitted in long holes provided in the respective ends 18b and 19b, and the bolts 28 and nuts 29 fixed to the mounting body 25 are used to mount the mounting bodies 24 and 25. And a spring 30, which is an elastic body, is disposed between the bolt 28 and the mounting body 24, and the interval between the mounting bodies 24 and 25, in other words, the upper frame 18 and the lower frame The gap 19 is a mechanism that can expand and contract. The spring 30 is adjusted so as to always bias in a direction to reduce the distance between the attachment bodies 24 and 25.
In this example, the spring 30 is provided only between the other ends 18b and 19b. However, a spring is provided also between the one ends 18a and 19a to provide a mechanism capable of expanding and contracting. It is of course possible to do so.

The annular frame 20 has a cylindrical pillow portion 32 (contact body) attached to each corner of each upper frame 18 and each lower frame 19 by screwing. The projection 32 projects in the inner diameter direction of the annular frame 20 and is in line contact with the outer wall surface of the tube 10. The pillow portion 32 is made of a material such as ceramics having lower thermal conductivity than metal.

Further, the ultrasonic probe 14 holding the ultrasonic transducer 12 is connected to the annular frame 2 via a rail 21.
0, and is pressed together with the holding plate 38 against the outer wall surface of the pipe 10 by a spring 36 which is an elastic body disposed between a holding screw 34 screwed to the rail 21 and the holding plate 38. ing. The housing of the ultrasonic probe 14, like the pillow portion 32, is preferably made of a material having low thermal conductivity.

According to the probe mounting jig 16 configured as described above, since the mechanism that can expand and contract is provided in a part of the annular frame 20, the water permeated between the annular frame 20 and the pipe 10 is provided. Or even if the moisture in the air freezes,
With the growth of the ice, the spring 30 contracts (extends as a whole the annular frame 20), and when the ice is melted by returning to normal temperature or the like, the spring 30 expands due to the restoring force of the spring 30 (as a whole the annular frame 20). By contraction, the change in the gap between the annular frame 20 and the tube 10 is reduced, so that the annular frame 20 always maintains a state in which the outer periphery of the tube 10 is tightened, and the ultrasonic probe 14 is attached to the outer wall surface of the tube 10. With constant contact, stable ultrasonic wave propagation and flow rate measurement can be performed.

When mounting the probe mounting jig 16 supporting the ultrasonic probe 14, the probe mounting jig 1
6 is only in contact with the pillow portion 32 that makes a line contact with the outer wall surface of the tube 10, so that the contact area is small. In particular, the contact surface between the outer surface of the tube 10 and the pillow portion 32 is a curved surface. The annular frame 2 is not affected by the friction of the outer surface of the pipe 10.
The clamping force of 0 can be transmitted to the pressing force of the ultrasonic probe 14 against the tube 10.

Further, since the contact area between the tube 10 and the pillow portion 32 is small, the propagation of heat between the tube 10 and the probe mounting jig 16 is reduced, and the vaporization of the liquefied gas in the tube is reduced. . In particular, since the pillow portion 32 is made of a heat insulating material having a low thermal conductivity such as ceramics, the propagation of heat can be further reduced. Therefore, the vaporization of the liquefied gas in the pipe 10 is reduced, and the cooling of the probe mounting jig 16 is eased during the mounting operation of the ultrasonic probe.
The mounting work is also facilitated.

If the upper frame 18 and the lower frame 19 adapted to the diameter of the tube 10 are used, the upper frame 1
8 and one end 18a and end 1 of lower frame 19
The two ultrasonic probes 14 for transmission and reception can be completely opposed by adjusting the distance between 9a and the other end 18b and 19b with the bolts 26 and 28 and the spring 30. Can be installed as you can. Further, by adjusting the rail 21 so as to be parallel to the axial direction of the tube 10, the parallelism between the axis of the ultrasonic probe 14 and the axis of the tube 10 can be easily maintained.

Instead of providing the pillow portion 32, the upper frame 18 and the lower frame 19 are brought into direct contact with the pipe 10 by making the insides of the upper frame 18 and the lower frame 19 curved surfaces having the same radius of curvature as the pipe 10. It can also be done.
In this case, the upper frame 18 and the lower frame 19 are preferably made of ceramic or the like having low thermal conductivity. Also,
Conventionally, the entire housing and probe mounting jig are covered with a heat insulating material such as glass fiber. However, this heat insulating material and the probe mounting jig 16 may be integrated.

[0021]

As described above, according to the present invention,
By providing an extendable mechanism on a part of the annular frame fixed to the tube by tightening the outer periphery of the tube,
When the water or air in the air that has soaked into the tube of the annular frame freezes, the expandable mechanism expands, and when the ice is melted by returning to normal temperature, the expandable mechanism contracts. By doing so, the annular frame can always maintain a state in which the outer periphery of the tube is tightened. Therefore, the contact between the ultrasonic probe and the tube can be kept constant, and stable ultrasonic wave propagation and flow measurement can be performed both in an extremely low temperature environment and in a normal temperature environment.

According to the second aspect of the present invention, the portion of the annular frame that comes into contact with the outer wall surface of the tube is made of a heat insulating material, so that the propagation of heat between the tube and the probe mounting jig is reduced. This has the effect that vaporization of the cryogenic fluid in the pipe is reduced, and the cooling of the probe mounting jig is eased during the mounting operation of the ultrasonic probe, so that the mounting operation is also facilitated.

According to the third aspect of the present invention, the annular frame has a contact body that is appropriately spaced in the circumferential direction and protrudes in the inner diameter direction, and the contact body is an outer wall surface of the pipe. As a result, since the contact area is reduced, the influence of friction on the tube surface can be reduced, and the clamping force of the annular frame can be effectively transmitted to the pressing force of the ultrasonic probe against the tube. In addition, the propagation of heat between the tube and the probe mounting jig is also reduced, and the evaporation of the cryogenic fluid in the tube is reduced, and the cooling of the probe mounting jig during the ultrasonic probe mounting operation is eased. Therefore, there is an effect that the attachment work is also facilitated.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an embodiment of a cryogenic ultrasonic flowmeter probe mounting jig according to the present invention.

FIG. 2 is a sectional view taken along line 2-2 in FIG. 3;

FIG. 3 is a view as seen from a direction of an arrow 3 in FIG. 1;

FIG. 4 is a perspective view showing a conventional cryogenic ultrasonic flow meter probe mounting jig.

[Explanation of symbols]

 Reference Signs List 10 tube 14 ultrasonic probe 16 probe mounting jig 20 annular frame 30 spring (expandable mechanism) 32 pillow (contact body)

Claims (3)

[Claims] A cryogenic ultrasonic flowmeter probe mounting jig for mounting an ultrasonic probe for measuring a flow rate of a fluid by radiating ultrasonic waves to a cryogenic fluid flowing in a pipe. There is provided an annular frame that supports the ultrasonic probe and is fixed to the tube by tightening the outer periphery of the tube, and a part of the annular frame is provided with an extendable mechanism. Cryogenic ultrasonic flow meter probe mounting jig. 2. The cryogenic ultrasonic flowmeter probe mounting jig according to claim 1, wherein a portion of the annular frame that comes into contact with the outer wall surface of the tube is made of a heat insulating material. 3. The annular frame has a contact body that is appropriately spaced in the circumferential direction and protrudes in the inner diameter direction, and the contact body is in line contact with the outer wall surface of the tube. The cryogenic ultrasonic flowmeter probe mounting jig according to claim 1 or 2.