JPS62261949A - Predicting device for damage in internal surface of tube - Google Patents

Abstract

PURPOSE:To predict the damage of a tube by mounting a device which consists of an easy-to-damage internal cylinder, an intermediate cylinder equipped with conduction sensors and a vacuum sensor, and an external sheath and is held under a vacuum between the internal cylinder and external sheath in a conduit. CONSTITUTION:A vacuum is produced in the gap 5 between the internal cylinder 1 which is easily damaged by the fluid in the tube and the external sheath 2 which protects the internal cylinder, and the intermediate cylinder 3 is arranged in the gap 5. Then, conduction sensors 6 and 7 provided to the cylinder 3 detect a leak of fluid from the cylinder 1 and the vacuum sensor 21 detects variation in pressure. Further, the thickness of the cylinder 1 can be measured by incorporating a thickness measurement sensor 20. This device is mounted on the straight and curved part of the conduit to predict the life of the tube internal surface depending upon corrosion, etc.

Description

[Detailed description of the invention] (a) Industrial application field This invention applies to pipes, multi-tube heat exchanger heat exchanger tubes, etc.
The present invention relates to a damage prediction device for the inner surface of a tube for detecting in advance when the inner surface of the tube is subject to erosion such as corrosion or erosion caused by fluid.

(b) Conventional technology For damage to the inner surfaces of pipes, multi-tube heat exchanger tubes, etc., it is necessary to periodically search for pinholes and erosion using pressure tests, ultrasonic testing, eddy current testing, etc. . However, the operating conditions, materials, diameters, wall thicknesses, etc. of the search locations are diverse, and it takes a lot of effort to prepare the conditions for the search locations.
The cost is required, the technical evaluation of search results is difficult,
There is a strong tendency for exploration to be avoided due to reasons such as this, and once an accident occurs, people tend to forget that they will suffer great damage.
The reality is that countermeasures are being taken with great urgency after an accident occurs.

For this reason, for example, the lifespan of heat exchanger tubes in a multi-tubular heat exchanger is to be predicted, and a lifespan informing device for heat exchanger tubes as disclosed in Japanese Utility Model Publication No. 51-51072 has been proposed.

In this method, short tubes that are easily corroded are installed in the flow path of the casing of a shell-and-tube heat exchanger to manage the life of the heat transfer tubes. Because the fluid flows outside the pipe in the part where the life is detected, it is difficult to reproduce the actual flow conditions inside the pipe, resulting in a decrease in the accuracy of life prediction.

(c) Problems to be solved by the invention Therefore, the present invention was created in view of the various existing circumstances as described above. For conduits that span multiple systems or heat transfer tubes for multipurpose heat exchangers, it is possible to obtain conditions that are representative of each system or location, and to anticipate in advance the areas that are likely to cause internal damage. Then, the pipe inner surface damage prediction device according to the present invention is attached to that part,
The aim was to predict and estimate the aging of individual systems and heat exchanger tubes based on the damage detected by this device, and to request countermeasures to be taken before actual damage occurs.

(d) Means for Solving the Problems The present invention will be explained based on the drawings. In Fig. 1, a damage prediction system [30 There is an outer casing 2 that protects the inner cylinder 1, which is easily damaged by fluid from the inner surface of the tube, and a gap 5 between the outer casing 2 and the inner cylinder 1 is maintained in a vacuum.
An intermediate cylinder 3 is arranged in the section.

When the fluid leaked from the inner cylinder 1 fills the space between the conductive sensors 6 and 7 provided in the intermediate cylinder 3,
A vacuum measurement sensor 21 for detecting a vacuum state is installed at the zero gap 5 where a current phenomenon occurs and detects damage to the inner cylinder 1. A wall thickness measurement sensor 20 that can measure the wall thickness of the inner cylinder 1 can also be incorporated.

The gap 5 is connected to a vacuum pump 16 via a self-containing pipe connector 13, 14 connected to a nozzle 11 provided in the outer ring box 2.
is evacuated.

Figure 2 shows a damage prediction device W131 for the inner surface of a heat exchanger tube in a multi-tube heat exchanger, which is suitable for installation in a curved pipe section of a pipeline. The inner cylinder 1, which is used as a heat exchanger tube 9132 and is configured to be thinner and more easily damaged than a heat exchanger tube, can be attached to the tube closing plate 4 by expanding the tube, by welding, or by welding, depending on the various materials of the heat exchanger tube.
It is fixed by mounting using a sealing method using an O-ring.

(e) Effect: Damage prediction device 30.3 on the inner surface of a pipe configured as described above.
1.32 maintains the gap 5 in a vacuum, which allows constant monitoring by the vacuum measurement sensor 20 using a diaphragm vacuum gauge, prevents troubles due to thermal expansion of the gap 5 due to fluid, and prevents the inner cylinder 1 from being damaged due to thermal expansion of the gap 5. Even if there is slight damage, fluid is sucked into the gap 5, so leakage detection accuracy can be improved.

Wall thickness measurement sensor 21 of the inner cylinder 1 installed in the gap 5
It is also possible to select an ultrasonic sensor, an eddy current sensor, etc. that is compatible with the material of the inner cylinder 1.

(F) Embodiment FIG. 1 shows an embodiment in which the orifice 26 is installed upstream of the damage prediction device 30 on the inner surface of the pipe. It is also possible to replace the source where the condition of the flow to the downstream side is likely to change, such as a container.

FIG. 4 shows an embodiment of the conductive sensor 6.7 provided in the intermediate cylinder 3 of the pipe inner surface damage prediction device 30. The intermediate cylinder 3 is made of a valve material suitable for fluid penetration. Even if the amount of leaked fluid is small, the sensitivity of current flow between the conductive sensors 6 and 7 can be increased. FIG. 5 shows an embodiment for predicting damage to the inner surface of the heat exchanger tubes of a shell-and-tube heat exchanger. An example in which a damage prediction device 32 is installed is shown.

By attaching a plurality of tube inner surface damage prediction devices 32 to locations of the heat exchanger tubes 29 where the flow velocity inside the tubes is substantially the same, it is possible to comprehensively manage aging of the heat exchanger tubes of a multi-tube heat exchanger.

(G) Effects of the Invention As explained above, the present invention is applicable to piping systems of various plants by detecting damage prediction devices 30 and 31 on the inner surface of the pipes in areas where the state of flow changes rapidly or in areas where the flow is steady. By selecting parts that flow well and using them in various combinations,
This has the effect of allowing system-wide lifespan management.

In a multi-tube heat exchanger, leakage damage due to inner surface erosion of heat transfer tubes is extremely large, so we recommend using a tube inner surface damage prediction device! 33
By installing the device in the fluid flow path, the effect of preventing accidents from occurring is significant.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a damage prediction device for the inner surface of a pipe installed in a straight pipe section, Figure 2 is a cross-sectional view of a damage prediction device for the inner surface of a pipe installed in a curved pipe section, and Figure 3 is a cross-sectional view of a damage prediction device for the inner surface of a pipe installed in a curved pipe section. A cross-sectional view of a device for predicting damage to the inner surface of a heat exchanger tube of a tubular heat exchanger, FIG. 4 is a cross-sectional view of an intermediate cylinder, and FIG. 5 is a cross-sectional view when implemented in a shell-and-tube heat exchanger. figure. 1...Inner pipe, 4...Closing plate, 8...Nozzle, 9...
- Clasp 10... Conduit, 11... Nozzle, 12...
Clasp 15...Pipe, 17...Control panel, 18...Power line, 19...Signal line. 22.23...Connection line, 24...Fluid inlet 25.
...Fluid outlet, 27...Heat exchange fluid inlet, 28...
heat exchange fluid outlet,

Claims (1)

[Scope of Claims] 1. An inner cylinder part is provided that is partially easily damaged so that damage to the inner surface of the pipe due to corrosion or erosion due to fluid can be predicted, and the inner cylinder part is protected by an outer cover case and is connected to the inner cylinder part. The gap with the outer casing is kept in a vacuum, and an intermediate cylinder is placed in this part, and the signal from the conductive sensor installed in the intermediate cylinder, which is energized by the penetration of fluid, and the signal of pressure change due to vacuum breakdown are constantly monitored. A damage prediction device for the inner surface of a tube, which is characterized by being able to detect damage to the inner surface of the inner cylinder. 2. The inside of the pipe according to claim 1, wherein the amount of thinning of the inner cylinder over time can be monitored by a wall thickness measurement sensor of the inner cylinder provided in the gap between the inner cylinder and the outer covering case. Surface damage prediction device. 3. Claims 1 and 2, characterized in that the device is installed as a device for predicting damage to the inner surface of the heat exchanger tubes in the flow path of the fluid in the heat exchanger tubes of the multi-tubular heat exchanger housing. The described device for predicting damage to the inner surface of a tube.