JP2962452B2 - Cryogenic equipment abnormality detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an abnormality in a cryogenic facility, and more particularly to a cryogenic facility suitable for use in detecting an abnormality such as a breakage of a facility, such as an air separation device, which occurs in a facility handling cryogenic substances. And an abnormality detection method.

[0002]

2. Description of the Related Art In a plant (cryogenic equipment) that handles cryogenic substances such as an air separation device and an argon purification device, all the internal equipment such as containers and piping constituting the plant is covered with a heat insulating material. When damage occurs to these containers and piping, it is very difficult to identify the damaged portion from outside the heat insulating material. Therefore, when an abnormality such as the above-mentioned damage occurs, the heat insulating material is usually removed, and the internal equipment itself is made visible to investigate the damaged part.

[0003] For example, in an air separation apparatus, main equipment such as a heat exchanger and a rectification tower, and internal equipment (low temperature substance storage section) such as piping for connecting them are housed in a box called a cold storage tank. In addition, a heat insulating material such as perlite is densely filled between the inner wall of the cold storage tank and internal equipment such as a rectification tower.

[0004] Therefore, when an abnormality such as breakage occurs in the internal equipment, low-temperature gas such as oxygen or nitrogen contained therein leaks into the cold storage tank, so that the pressure in the cold storage tank increases. Therefore, the fact that an abnormality such as breakage has occurred can be detected.

[0005]

However, as described above, it is not possible to identify a location where an abnormality has occurred only by an increase in the pressure in the cold storage tank. Therefore, heat insulation such as perlite filled inside the cold storage tank is not possible. Unless the material is removed, there is a problem that the location where the above-mentioned abnormality occurs cannot be specified.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional problems, and is capable of easily specifying a location where an abnormality such as breakage has occurred in a facility handling low-temperature substances when the facility handles the substance. It is an object of the present invention to provide a method for detecting an abnormality.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a metal gauze disposed at a predetermined position outside a low temperature substance storage section of a low temperature facility.
In pipes, even in environments exposed to cryogenic temperatures
And laying set the optical fiber fabricated by the reduction was not fiber preform and the sheath material, the optical fiber the temperature of the position along the optical fiber was measured by the temperature distribution measurement apparatus according to the temperature sensor, the temperature change is detected This problem has been solved by determining that an abnormality has occurred in the vicinity of the position.

[0008]

According to the present invention, in a metal guide pipe disposed outside a low-temperature substance storage section in a low-temperature facility.
In addition, an optical fiber that does not deteriorate even at extremely low temperatures is provided, and a temperature change is detected by measuring a temperature at a position along the optical fiber with a temperature distribution measuring device using the optical fiber as a temperature sensor. In such a case, it was determined that an abnormality occurred near the measurement position.
Without removing the heat insulating material, it is possible to accurately detect at which position in the low-temperature substance storage unit an abnormality such as breakage has occurred.

Therefore, for example, when equipment breakage occurs in a plant that handles cryogenic substances such as an air separation device or the like, the vicinity of the damaged area due to the cryogenic substance such as liquid nitrogen or liquid oxygen leaking from the damaged area. By detecting the temperature change, it is possible to identify the above-mentioned damaged portion.

The temperature distribution measuring device detects Raman scattered light returning to the incident side when light is incident on an optical fiber in a time-division manner, and detects the Stokes contained in the Raman scattered light detected at each time. By determining the temperature of the scattering point from the intensity ratio of light / anti-Stokes light and specifying the position of the scattering point from the return time of the Raman scattered light,
One having a function of measuring the temperature at an arbitrary position along the optical fiber can be used.

The above-mentioned temperature distribution measuring device is an optical fiber type temperature distribution device which has already been proposed by the present applicant in Japanese Patent Application Laid-Open No. Hei 5-1314 and which allows light to enter from both ends of an optical fiber. A measuring device can also be used.

[0012]

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

FIG. 1 is an explanatory view conceptually showing an air separation apparatus (low temperature equipment) and an optical fiber type temperature distribution measuring apparatus to which the first embodiment according to the present invention is applied, and FIG. It is a schematic structure figure of a fiber type temperature distribution measuring device.

Air separation apparatus 1 to which the method of the present embodiment is applied
Numeral 0 is provided with a cooling tank 12, a rectification tower 14 installed inside the cooling tank 12, and a pipe 16 connected to the rectification tower 14.

In the above-mentioned air separation device 10, a measuring device main body 18 constituting an optical fiber type temperature distribution measuring device (hereinafter, also simply referred to as a measuring device) and an optical fiber 20 serving as a sensor are connected to a rectification tower 14 and a pipe. It is disposed outside the low-temperature substance storage section such as the sixteen.

First, the optical fiber type temperature distribution measuring device will be described in detail. This measuring device has a function of measuring the temperature distribution along the optical fiber 20 by connecting one end of the temperature measuring optical fiber 20 laid along the object to be measured to the measuring device main body 18.

As shown in FIG. 2, the measuring device main body 18 includes an optical fiber 20 as a sensor unit, a laser diode LD as an optical oscillator, and first and second optical detectors as photodetectors.
And a measurement unit 22 having the avalanche photodiodes APD1 and APD2.

In this measuring device, the laser diode LD and the photodiodes APD1, APD2 are optically connected to the optical fiber 20, and the laser diode LD is driven by a pulse signal from a pulse drive circuit 24.
When the laser light is pulse-oscillated, the laser light enters the optical fiber 20 from one end thereof.

When a laser beam is incident on the optical fiber 20, scattered light or the like returns to the one end where the laser beam has been incident.
And through the second interference filters 28A and 28B, are detected by the photodiodes APD1 and APD2.

The light detected by the photodiodes APD1 and APD2 is converted into an electric signal by a high-speed averaging processor 3.
After the data is input to 0 and a predetermined process is performed, a temperature distribution at a position along the optical fiber is displayed on a temperature distribution display 34 via a data processing device 32.

The measuring principle of this device will be described below.

A laser beam is periodically or appropriately incident on the optical fiber 20 in a pulsed manner. At that time, Raman scattered light which is scattered and returned from each point in the length direction of the optical fiber 20 is returned. Detect by time division.

When the pulse light is incident on the optical fiber 20 as described above, the light propagates inside the optical fiber, and each point of the optical fiber 20 generates scattered light in accordance with the temperature thereof. Part of the scattered light returns to the incident side as backscattered light. The position where the backscattered light is generated can be specified by the time required until the scattered light returns.

In the backscattered light, in addition to the Rayleigh scattered light generated by being elastically scattered by the lattice vibration of the glass constituting the optical fiber, the Raman scattered light generated by inelasticity is also included. It is included. The Raman scattered light is composed of Stokes light and anti-Stokes light, and the intensity ratio of the two lights theoretically depends only on the temperature if the wavelength of the incident light and the composition of the glass are determined.

Accordingly, as described above, the Stokes light and the anti-Stokes light included in the Raman scattered light returning after the laser light is incident are detected by the first and second photodiodes APD1 and APD2 in a time-division manner, and The temperature is determined from the intensity ratio of the Stokes light / anti-Stokes light calculated by the high-speed averaging device 30, and the position in the length direction of the optical fiber 20 is determined at intervals of, for example, 1 m from the time required to return. Can be identified.

The length of the optical fiber 20 used for measurement can be extended to about 2 km, so that the total length is 2 km.
The temperature distribution for every 1 m during the measurement can be measured with one optical fiber.

In the present embodiment, the optical fiber 20 is laid around a portion of the low-temperature substance storage section that is likely to be damaged. At this time, if the optical fiber 20 is brought into direct contact with a low-temperature substance storage unit such as a pipe, the temperature change when the storage unit is damaged is small, and it is difficult to measure. It is preferable to lay it.

As shown in FIG. 3, it is preferable that a guide pipe 32 made of stainless steel, aluminum or the like is previously installed at a predetermined position, and the optical fiber 20 is laid therein. Also, as the optical fiber 20 to be used,
Since it is exposed to an extremely low temperature of about -190 ° C., a fiber made of a fiber preform and a sheath that does not deteriorate even in such an environment is used.

In this embodiment, the optical fiber 20 serving as the sensor is disposed outside the low-temperature substance storage section such as the rectification tower 14 and the pipe 16, and the temperature distribution at a position along the optical fiber 20 is measured. Since the measurement can be performed, the temperature distribution is measured over time, and when an abnormal temperature change is detected, it can be detected that an abnormality has occurred near the detected position.

More specifically, in an air separation apparatus that is a plant that handles cryogenic substances, if equipment such as a crack in the vessel (rectification tower 14) or a break in the pipe 16 occurs, the inside of the equipment is damaged. Since the extremely low temperature gas or liquid contained in the gas flows out into the heat insulating material, the temperature in the vicinity of the damaged portion decreases. Accordingly, in the case of a portion where breakage or the like is highly likely to occur, for example, in the case of the pipe 16, if the temperature in the vicinity of the connecting portion of the bellows-shaped expansion and contraction portion is measured as shown in FIG. It is possible to detect that a leak of a low-temperature substance has occurred due to breakage or the like due to a large temperature drop.

As described above, according to the present embodiment, only by laying the optical fiber 20 along the vicinity of the site where there is a possibility of breakage, breakage etc. can be performed over a wide range of the target equipment. Can be detected.

Therefore, in the above-described abnormality detection, the temperature distribution is continuously or periodically measured by a measuring device, and when the temperature in the steady state largely changes to the low temperature side, for example, an alarm is issued to change the temperature. By informing the plant operator of the location and its temperature, it is possible to quickly take appropriate measures.

When the above-described abnormality detection is performed by using a thermocouple, a resistance temperature detector, or the like as a sensor as in the related art, the temperature can be measured only in an extremely narrow facility range.
In order to detect damage to the entire equipment, an enormous number of sensors are required.

As described in detail above, according to this embodiment, when an abnormality such as equipment breakage occurs in the air separation device, the occurrence can be quickly detected and the location of the occurrence can be accurately known. it can. As a result, it is easy to repair an abnormal state such as breakage, and the time required for the repair can be reduced.

FIG. 4 is an explanatory view showing a schematic configuration of a main part of an optical fiber type temperature distribution measuring apparatus applied to the abnormality detecting method according to the second embodiment of the present invention.

There are a plurality of measuring devices used in this embodiment.
For example, a sensor unit is configured by 40 optical fibers 20,
The plurality of optical fibers 20 are connected to a single-core connection optical fiber 20A via an optical switch 38, and the connection optical fiber 20A is connected to the measurement device main body 18.

The apparatus main body 18 is a data processing apparatus 3 integrated with a display 34 comprising a CRT.
2, a control signal is output from the data processing device 32 to the optical switch 38, and the optical fiber 20 to be measured by the optical switch 38 is appropriately switched.

Except for the features described above, the optical fiber type temperature distribution measuring apparatus used in this embodiment is substantially the same as that used in the first embodiment.

According to the present embodiment, a plurality of optical fibers 20 are respectively laid on a plurality of laying routes, and an optical switch 38 is provided.
, The temperature distribution of each route can be measured by sequentially switching the routes.

Therefore, even if the entire route cannot be covered by one optical fiber 20 as in the case where the installation route is very complicated and the route has many bends, the accurate temperature can be obtained. Since the distribution can be measured, it is possible to easily and accurately detect an abnormality occurrence position.

Although the present invention has been described in detail, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof.

For example, the low-temperature equipment to which the method of the present invention can be applied is not limited to the above-mentioned air separation device, but also includes a relatively low-temperature equipment such as a purifier for argon or helium which handles cryogenic substances. Any equipment can be applied as long as it handles equipment while keeping the material cool.

[0043]

As described above, according to the present invention,
When an abnormality such as breakage occurs in equipment handling low-temperature substances, the location of the abnormality can be easily specified.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of an air separation device to which a first embodiment of the present invention is applied;

FIG. 2 is a schematic configuration diagram of an optical fiber type temperature distribution measuring device applied to the method of the present embodiment.

FIG. 3 is an explanatory diagram showing an example of an optical fiber laying method.

FIG. 4 is an explanatory diagram showing a main configuration of a temperature distribution measuring device applied to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Air separation apparatus 12 ... Cold storage tank 14 ... Rectification tower 16 ... Piping 18 ... Measuring apparatus main body 20 ... Optical fiber 22 ... Measurement part

Claims (2)

(57) [Claims] 1. A predetermined position outside a low-temperature substance storage section of a low-temperature facility.
Cryogenic temperature inside a metal guide pipe
Fiber preform and sheath that do not degrade in exposed environments
An optical fiber fabricated by the scan material laid to set, the optical fiber the temperature of the position along the optical fiber was measured by the temperature distribution measurement apparatus according to the temperature sensor, abnormality in the vicinity of a position where the temperature change is detected A method for detecting an abnormality in a low-temperature facility, wherein it is determined that an error has occurred. (2) In claim 1, A plurality of optical fibers as the temperature sensor are laid,
Optical fiber for single core connection connected to the main unit
The optical switch is connected to an optical fiber through an optical switch.
Switch to switch between the multiple optical fibers and measure the temperature.
A method for detecting abnormalities in low-temperature equipment.