JPS62151736A - Detecting device for leak in heat exchanger pipe - Google Patents

Abstract

PURPOSE:To confirm the position of a leak in a heat exchanger pipe from outside a furnace in a hot banking state and to grasp the extent of the damage to the heat exchanger tube by entering a laser beam into the furnace through a furnace observation hole. CONSTITUTION:A laser beam generating device 4 is provided to a furnace observation window 2a in the furnace wall 3 of a boiler and a TV camera 5 connected to an image processor 6 is provided to a furnace observation window 2b. The laser beam 10 generated by the generating device 4 is converged by a condenser lens 13 to scan in a combination chamber 12 through the rotation of a rotary reflecting mirror 15. Then the operation of the boiler is stopped to enter the hot banking state and the laser 10 is made incident in the direction of the abnormal sound generation position in the combustion chamber 12 which is detected roughly by a noise meter. For example, when a gas laser using mixed gas of He-Ne is used, an intense red scattered beam 14 is emitted from the crossing area between the laser beam 10 and leak steam 9. This scattered light beam 14 is picked up by the camera 5 to discriminate the presence of the leak steam 9 and the amount of the leak steam 9 is detected from the intensity of the red light emission.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a heat exchanger tube leakage detection device, and particularly to a heat exchanger tube leakage detection device suitable for detecting a leakage location in a heat exchanger tube of a boiler.

[Background of the invention]

When the heat transfer tubes of a boiler are damaged due to thermal stress, corrosion, etc. and water vapor or steam leaks into the boiler, the operation of the boiler must be stopped and the damaged area must be repaired.

Conventionally, such leakage of water vapor or steam from heat transfer tubes has often been discovered by on-site patrol personnel who hear unusual sounds from steam jets. A sound level meter with a microphone is then used to detect the location of the abnormal sound from outside the furnace, but the accuracy is limited to detecting the location within a few meters around the actual location of the abnormal sound. Ta.

Therefore, in order to finally confirm the location of the leak, the boiler must be shut down and the inside of the furnace forcibly cooled down to a temperature (approximately It was necessary to lower the temperature inside the furnace until it reached 50°C. Therefore, even if the damage to the heat exchanger tubes is found to be relatively light and the boiler can continue to operate as is after inspecting the leakage location, it may take approximately one day or more to restart the boiler. During this period, steam could not be generated and therefore the turbine generator could not be operated to supply electricity, resulting in a loss.

For this reason, on-site patrol personnel listen for abnormal sounds caused by water vapor or steam leakage from heat exchanger tubes, and use a sound level meter from outside the furnace to determine the location within a few meters of the actual location where the abnormal sound is occurring. If detected, stop boiler operation and do not forcibly cool down the inside of the furnace until it reaches a temperature that allows inspectors to enter the furnace, and do so-called hot banking (burner extinguishing, forced fan stoppage, boiler shutoff). Keep the temperature inside the furnace at 200 to 3000C by closing the rod damper), check the leakage points of the heat transfer tubes from outside the furnace without entering the furnace, and check the leakage points of the heat transfer tubes from outside the furnace. There was a request for four heat exchanger tube leakage detection devices that would be able to determine the extent of damage to the tubes.

[Object of the invention] This invention was made in response to the above demand.
In the event that steam or steam leaks due to damage to the heat transfer tubes of the boiler, the boiler operation will be stopped and the furnace will not be forcibly cooled down to a temperature that allows inspectors to enter the furnace. A heat exchanger tube leak detection device that allows you to check the leakage location of heat exchanger tubes from outside the furnace while hot banking is in progress, as well as determine the amount of leakage of water vapor or steam, that is, the degree of damage to the heat exchanger tubes. The purpose is to provide the following.

[Summary of the invention]

In this invention, when the boiler's heat transfer tubes are damaged and water vapor or steam leaks, the boiler operation is stopped and the furnace remains in a hot banking state, and a laser beam is directed into the furnace through the furnace viewing window and scanned. Then, the laser beam intersects with the leaked water vapor and the scattered light is imaged by a TV camera from another furnace viewing window, and the position, area, and location of the bright part of the image are determined.
Check the location of the leak from outside the furnace by checking the brightness, etc., and
This method is characterized by determining the amount of leaked water vapor, that is, the degree of damage to the heat exchanger tubes.

[Embodiments of the invention]

An embodiment according to the present invention will be described based on FIG. 1ζ.

Fig. 1 is a perspective view showing the arrangement of the heat transfer tube leak detection device of the present invention, Fig. 2 is a diagram showing the principle of leak detection by the heat transfer tube leak detection device of the present invention, and Fig. 3 is a diagram showing the principle of leak detection by the heat transfer tube leak detection device of the present invention. It is a figure showing one example.

As shown in FIG. 1, the heat exchanger tube leak detection device of the present invention includes a laser beam generator 4 in the furnace viewing window 2a of the furnace wall 3 of the boiler, and an image processing device 6 in the furnace viewing window 2b.
A television camera 5 connected to each is provided. The image processing device 6 performs arithmetic processing on the position, area, brightness, etc. of the bright part of the image captured by the television camera 5, confirms the leakage location, and detects the amount of leakage. Further, the laser beam 10 generated from the laser beam generator 4 can scan the inside of the combustion chamber 12 of the boiler.

Because of this arrangement, as shown in FIG. The patrolman hears the unusual sound of a steam leak. Once the approximate location of the abnormal sound is detected from outside the furnace using a sound level meter, the boiler is shut down and placed into hot banking mode.

In this state, when the laser beam 10 is incident in the direction of the abnormal sound generation point detected at the approximate position inside the reactor 12, the laser beam 10 and the leaked steam 9 intersect and the intersection area 11
occurs.

Since the leaked water vapor 9 has a relatively large particle size of submicron or more, the amount of light scattered by the laser beam 10 by the leaked water vapor 9 is large in the intersection region 11. Therefore, if the laser beam generator 4 is a gas laser of He--Ne mixed gas, for example, the strong red scattered light 1 will be emitted from the intersection area 11.
4 emits light. In addition, the intersection area 11 of the laser beam 10
The other portions are scattered by dust in the air within the combustion chamber 12, so the amount of scattered light is small and the light is weakly emitted in red.

In this case, the inside of the boiler in hot banking condition is
Normally, the illuminance is less than 1fX and it is very dark, so it is several meters
Even if the beam IO has a small output energy of W class, the scattered light beam 14 can be sufficiently imaged by the television camera 5.

Therefore, when the inside of the reactor 12 is imaged with the television camera 5, the presence of the intersection area 11, that is, the leaked steam 9 can be clearly identified. That is, the position and shape of the leaked water vapor 9 can be determined by scanning the laser beam 10.
Furthermore, the amount of leaked water vapor 9 can be detected based on the intensity of red light emitted from the scattered light rays 14 in the intersection area 11. Therefore, the inside of the furnace 12 is imaged by the television camera 5, and the position, area, brightness, etc. of the bright part of the image are processed by the image processing device 6, thereby confirming the leakage point 8 of the heat exchanger tube 7. It is possible to grasp the amount of leaked water vapor 9, that is, the degree of damage to the leakage location 8 of the heat exchanger tube 7.

As shown in FIG. 3, a method for scanning the laser beam 10 is to converge the laser beam 10 generated from the laser beam generator 4 using the converging lens 13 and rotate the rotating reflective mirror 15 to scan the laser beam 10.
can be scanned. In addition, one rotation reflection mirror 15
Instead, if a diffraction grating such as an optical fiber diffraction grating is used, multiple laser beams can be generated without scanning the laser beam 10, so leakage at multiple locations can be detected simultaneously. Leakage location confirmation work can be done in a short time.

In this embodiment, a case where a laser beam is used has been described, but any light beam other than a laser beam may be used as long as it is narrowly focused.

〔Effect of the invention〕

According to this invention, when the heat exchanger tubes of a boiler are damaged and water vapor or steam leaks, it is possible to stop the operation of the boiler and check the leakage location of the heat exchanger tubes from outside the furnace while the boiler remains in a hot banking state. At the same time, it is possible to grasp the amount of leaked steam, that is, the degree of damage to the heat exchanger tubes, so if the degree of damage to the heat exchanger tubes is relatively light and it is safe to continue operating the boiler, , the boiler can be started immediately to generate steam in a short time, and the steam can be used to drive a turbine generator and supply electricity. Therefore, there is an effect that the influence on power supply is small.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the arrangement of the heat transfer tube leak detection device of the present invention, Fig. 2 is a diagram showing the principle of leak detection by the heat transfer tube leak detection device of the present invention, and Fig. 3 is a diagram showing the principle of leak detection by the heat transfer tube leak detection device of the present invention. It is a figure showing one example. l...Water cooling wall 2a, 2b...Furnace viewing window 3...Furnace wall 4...Laser beam generator 5...TV camera 6...Image processing device 7
... Heat exchanger tube 8 ... Leakage point 9 ... Leakage steam 10 ... Laser beam 11 ... Intersection area 12 ... Combustion chamber 13 ... Convergence lens
14...Scattered light rays 15...Rotating reflection mirror

Claims (3)

[Claims] (1) In a heat exchanger tube leakage detection device for detecting leakage in a heat exchanger tube of a steam generator, an imaging device having a light beam generator and an image processing device is provided in the furnace viewing window of the steam generator. A heat exchanger tube leak detection device characterized by: (2) The heat exchanger tube leak detection device according to claim 1, wherein the light beam generator has a light beam scanning mechanism. (3) The heat exchanger tube leak detection device according to claim 1, wherein the light beam generator has a diffraction grating.