JPS6044609B2 - Ultrasonic measuring device - Google Patents

Description

Detailed Description of the Invention The present invention arranges two ultrasonic transducers on the same side of a pipe through which a fluid to be measured flows, and emits ultrasonic waves from one of the ultrasonic transducers toward the fluid to be measured. The present invention relates to an ultrasonic measuring device in which the other ultrasonic transducer receives ultrasonic waves that have passed through a fluid to be measured and reflected off the inner wall surface of the pipe.

In an ultrasonic measuring device, for example, an ultrasonic flowmeter, detectors (ultrasonic transducers) D and D' are placed on the upstream and downstream sides of the flow of the fluid to be measured, as shown in Figure 1. There is a method that propagates ultrasonic pulses.

The flow rate is measured by taking advantage of the time difference that occurs between the ultrasonic pulse propagation time from the upstream side to the downstream side and the propagation time from the downstream side to the upstream side due to the flow. Second
The figure is a perspective view of a conventional ultrasonic measuring device of this type.

In FIG. 2, numeral 1 indicates a pipe through which a high-temperature measurement fluid 2 flows. The side detector 3 and the downstream detector 4 are attached to the same side of the pipe 1. The signals from both detectors 3 and 4 must be sent to a distant control circuit, but the normal temperature coaxial cable used for this is limited in its heat resistance to, for example, 100 degrees Celsius or less. As shown in FIG. 2, heat-resistant electric wires 6 and 7 such as MI cables are used in the vicinity of the piping 1 where the temperature is high (100 DEG C. to 500 DEG C.). Since the heat-resistant wires 6 and 7 are covered with a metal sheath, they have extremely poor flexibility.
It is also heavy and expensive, so it is used only in limited areas, and the relay terminal box 8 is placed in a place where the ambient temperature is not affected by the high temperature of the pipe 1. The terminals of the heat-resistant wires 6 and 7 are connected to this relay. Connected to terminal box 8. The relay terminal box 8 is connected to a measurement circuit (not shown) via ordinary coaxial cables 9 and 10. However, since the heat-resistant wires 6 and 7 in this structure are made of a metal sheath filled with insulating powder such as alumina, they have poor flexibility, are rigid, and are heavy, resulting in the following disadvantages.

(a) Wiring work is difficult due to poor flexibility. (b) If it is shipped after being combined with the detector frame during manufacture, it will be bulky and undesirable for transportation. (C) If a worker accidentally puts a heat-resistant wire on his or her foot during installation, removal, or maintenance inspection, the heat-resistant wire is rigid, so there is a high possibility of damaging the connection point with the detector. (d)
Because heat-resistant wires have poor flexibility and are expensive, they cannot be laid for long periods, so they must be kept to a certain length and connected to the measurement circuit by changing the connection with a regular cable, so the relay end must be ! It is necessary to install a child box. By the way, with this type of ultrasonic meter, measurements can be made without contacting the fluid by simply attaching the detector to the outer wall of the piping through which the fluid to be measured flows, and it can also be installed later on existing piping. Because of the advantage of being able to be installed later on to existing pipelines, detectors are often installed and removed on-site at existing plants.

However, the working environment may be harmful to humans, such as high temperatures and a radiation atmosphere. Therefore, this type of ultrasound 4
(a) quick installation and removal work,
Furthermore, the structure does not require difficult adjustments and is easy to work with; (b) the structure is easy to maintain; (c)
When the fluid to be measured is a high-temperature fluid (100 to 500°C) or a cryogenic fluid (liquid nitrogen, liquid hydrogen, etc.), the operator must measure the temperature or It is required that it not be affected by extremely low temperatures. An object of the present invention is to provide an ultrasonic measuring device that eliminates the disadvantages of the conventional device shown in FIG. 2 and also satisfies all of the above requirements.

Embodiments of the present invention will be described below with reference to the drawings.

3 is a perspective view of an ultrasonic flowmeter which is an embodiment of the present invention, FIG. 4 is a view taken along arrow A in FIG. 3, and FIG. 5 is a cross-sectional view of the main parts in FIG. 3. 1 in the figure is a pipe through which the fluid 2 to be measured flows. In this piping 1, a frame 12 holding the side detector 117 and the downstream detector 13 and a frame 14 formed separately from this frame 12 are rotatable at one end with a hinge pin 15. The frame bodies 12 and 14 are hinged together and installed so that the pipe 1 is sandwiched between the frames 12 and 14, and a J-tightening fitting 15'' is attached at the other end of the frame bodies 12 and 14.
It is tightened and fixed. This frame body 12 is provided with pipe mounting seats 16 and 17.
Hollow tubes (for example, stainless steel tubes) 18 and 16 are screwed into the tubes 7 and fixed by other methods. The hollow portions of the hollow tubes 18 and 19 can be filled with a heat insulating material if necessary.
Lead wires 28 from the detectors 11 and 13 penetrate in the axial direction.
Pass through. The end of each lead wire 28 is connected to a hollow tube 18,
Connection terminal (receptacle) 20, 2 provided at the tip of 19
Connect to 1. If necessary, heat radiation fins 22 and 2 are provided at the tips of the hollow tubes 18 and 19 adjacent to the connection terminals 20 and 21.
3 may be provided. Reference numerals 24 and 25 are the mating connection terminals (plugs) of the connection terminals 20 and 21, respectively, and the ends thereof are connected to ordinary coaxial cables 26 and 27, and detection can be made by connecting the connection terminals 20, 21, 24, and 25, respectively. The signals from the devices 11 and 13 are connected to the respective lead wires 2.
8, connection terminals 20, 21, 24, 25, coaxial cable 2
It is transmitted to the control circuit via 6 and 27.

Here, the hollow tube is made of a heat-resistant material with as low thermal conductivity as possible, and by providing a large temperature gradient in the axial direction of the hollow tube, even if the pipe 1 is at a high temperature, the connecting terminal 20,
At parts 21, 24, and 25, a temperature sufficiently close to room temperature should be obtained. The heat dissipation fins are connected to the connection terminals 20, 21, 2.
The purpose of this installation is to bring the temperature of parts 4 and 25 closer to room temperature. Also, the connection terminal (receptacle) 20,
21 and the mating connection terminals (plugs) 24, 25 can be connected with one touch, so that the workability 3 of cable connection and installation is extremely good. Although the case where the fluid to be measured is at a high temperature has been described above, the present invention can be applied even when the fluid to be measured is at a low temperature.

However, in that case, the only difference is that the hollow tube is made of a cold-resistant material, and the heat radiation fins function as heat collectors. With the above structure, the high temperature (or low temperature) of the piping section will not affect the coaxial cable, and the workability and maintainability of installation and removal will be extremely improved.

According to the results of actually building a test machine and conducting experiments, it takes about 1 minute to attach the detector, detector, and frame to the piping, and it takes about 1 minute to connect the connection terminal on the detector side and the connection terminal on the coaxial cable side. The time was less than 108', and the workability at the plant site was improved. Furthermore, piping 1 and frame bodies 12,1
4 was a high temperature close to 300℃, but by using 15C71 hollow tubes (stainless steel tubes) 18 and 19, the temperature at the connecting terminals 20 and 21 could be brought to room temperature. In other words, it was possible to reduce the temperature of the hollow tubes 18 and 19 from 300°C to room temperature. Therefore, the main points of the present invention explained above can be summarized as follows.

(1) In the present invention, both ultrasonic transducers (
A frame 12 and a frame 14, which hold the detector 11 and the detector 13), are hingedly connected at one end by a hinge pin 15, and both frames 12 and 14 are connected to each other so as to sandwich the pipe 1. The free end sides of both frames 12 and 14 are tightened by tightening means (clamping fittings 15'').

As a result, installation and removal work can be carried out quickly, and difficult adjustments are not required, making it possible to improve work efficiency. This also made maintenance easier. 2) In the present invention, each lead wire 28 of the ultrasonic transducer is passed through the inside of the hollow tubes 18 and 19 fixed to the frame 12, and is connected to the tip of each of the hollow tubes 18 and 19. It was designed to connect to the provided connection terminals (receptacles) 20 and 21.

As a result, the hollow tube can achieve a significant temperature drop from the frame to the connection terminal, so even if the fluid to be measured is a high temperature fluid of, for example, 100°C to 500°C, It has become possible to maintain the connection terminals 20 and 21 at room temperature. Furthermore, since the length of the heat-resistant wire can be made almost the same as the length of the hollow tube, it has become possible to avoid the disadvantages of the conventional device shown in FIG. 2.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram of an ultrasonic flowmeter, Fig. 2 is a perspective view of a conventional ultrasonic flowmeter, and Fig. 3 is a perspective view of an ultrasonic flowmeter according to an embodiment of the present invention. 4 is a view taken in the direction of arrow A in FIG. 3, and FIG. 5 is a sectional view of a main part in FIG. 3.

Claims (1)

[Claims] 1. Two ultrasonic transducers are placed on the same side of the pipe through which the fluid to be measured flows, and one ultrasonic transducer emits ultrasonic waves toward the fluid to be measured, thereby causing the fluid to be measured to flow. In the device in which the other ultrasonic transducer receives the ultrasonic waves reflected from the inner wall surface of the pipe that has passed through, a frame body for holding both the ultrasonic transducers and a frame body formed separately from this frame body are arranged at one end thereof. The frames are hinged at the sides and attached to the piping so as to sandwich the piping, and the free ends of the frames are tightened by a tightening means, and each lead of the ultrasonic transducer is attached to the piping. The wires are passed through hollow tubes each fixed to a frame holding both the ultrasonic transducers and connected to connection terminals provided at the tips of each of the hollow tubes. Ultrasonic measuring device. 2. The ultrasonic measuring device according to claim 1, wherein the hollow tube through which the lead wire passes is provided with heat dissipation fins in a portion close to the connection terminal. .