HK1241456B - Optical fiber temperature distribution measurement system and optical fiber temperature distribution measurement method - Google Patents

Description

Optical fiber temperature distribution measurement system and optical fiber temperature distribution measurement method

Technical Field

The present invention relates to an optical fiber temperature distribution measurement system and an optical fiber temperature distribution measurement method for detecting roller abnormality of a belt conveyor.

Background Art

There is known a system configured to measure the temperature near a belt conveyor by using an optical fiber temperature distribution measuring device (DTS: Distributed Temperature Sensor) and detect ignition of the belt conveyor.

The configuration of measuring the temperature near the belt conveyor and detecting the fire of the belt conveyor is very beneficial because it can achieve initial fire extinguishing. However, the information obtained by the temperature near the belt conveyor is not limited to the occurrence of fire.

For example, if a belt conveyor's rollers fail to rotate smoothly due to a malfunction, aging, or other factors, the temperature of the rotating parts increases due to friction. Therefore, roller anomalies can be detected by measuring the temperature near the belt conveyor. Because roller anomalies can increase the load on the belt conveyor and the temperature increase caused by friction can cause fire, it is desirable to detect roller anomalies at an early stage.

[Patent Document 1] Japanese Patent Application Publication No. 2014-83297A

However, the temperature increase caused by roller anomalies is very low compared to the temperature during a fire and is also localized. Therefore, the temperature may be masked by noise or may not be sufficiently represented by the measured value due to the limited spatial resolution of the fiber optic temperature distribution measurement device.

Considered configurations include coiling the optical fiber around the roller to ensure a sufficient length of the optical fiber placed near the roller, or placing the optical fiber in close contact with a metal portion configured to support the roller to detect subtle temperature changes. However, these configurations must be used for each roller. Consequently, the required work of laying the optical fiber is laborious, increasing costs.

Summary of the Invention

Exemplary embodiments of the present invention provide an optical fiber temperature distribution measurement system and an optical fiber temperature distribution measurement method that can simply detect abnormalities in rollers of a belt conveyor through a simple work of laying optical fibers.

An optical fiber temperature distribution measurement system according to a first aspect of the present invention is a system configured to allow an optical pulse to be incident on an optical fiber and to measure temperature distribution in units of spatial resolution regions based on return light from the optical fiber, the system comprising:

a temperature difference calculator configured to calculate a temperature difference between corresponding spatial resolution areas based on a first temperature distribution obtained by return light from a first optical fiber section laid along the roller row and a second temperature distribution obtained by return light from a second optical fiber section laid side by side with the first optical fiber section at a position farther from the roller row than the first optical fiber section; and

An abnormality detector is configured to calculate a temperature difference for evaluation for each spatial resolution area, and when the calculated temperature difference for evaluation exceeds a reference value, determine that an abnormality has occurred in the roller near the spatial resolution area, and the temperature difference for evaluation is the sum of the temperature difference of each spatial resolution area and the temperature difference of the spatial resolution area adjacent to it.

An optical fiber temperature distribution measurement system according to a second aspect of the present invention is configured to allow a light pulse to be incident on an optical fiber and to measure temperature distribution in units of spatial resolution regions based on return light from the optical fiber, the system comprising:

a temperature difference calculator configured to calculate a temperature difference between corresponding spatial resolution areas based on a first temperature distribution obtained by return light from an optical fiber portion laid along a roller row and a second temperature distribution calculated from temperatures of spatial resolution areas excluding adjacent spatial resolution areas in the first temperature distribution; and

An abnormality detector is configured to calculate a temperature difference for evaluation for each spatial resolution area, and when the calculated temperature difference for evaluation exceeds a reference value, determine that an abnormality has occurred in the roller included in the spatial resolution area, and the temperature difference for evaluation is the sum of the temperature difference of each spatial resolution area and the temperature difference of the spatial resolution area adjacent to it.

An optical fiber temperature distribution measurement system according to a third aspect of the present invention is a system configured to allow a light pulse to be incident on an optical fiber and to measure temperature distribution in units of spatial resolution regions based on return light from the optical fiber, the system comprising:

A data processor configured to:

calculating a temperature distribution of a first temperature obtained by return light from a first optical fiber section laid along the roller row and a temperature distribution of a second temperature obtained by return light from a second optical fiber section laid side by side with the first optical fiber section at a position farther from the roller row than the first optical fiber section,

A temperature difference for evaluation is calculated for each spatial resolution region, the temperature difference for evaluation being the difference between the sum of the first temperature of each spatial resolution region and the first temperature of the spatial resolution regions adjacent thereto and the sum of the second temperature of each spatial resolution region and the second temperature of the spatial resolution regions adjacent thereto, and

When the calculated temperature difference for evaluation exceeds the reference value, it is determined that an abnormality has occurred in the roller near the spatial resolution area.

A method for measuring temperature distribution of an optical fiber according to a fourth aspect of the present invention is a method for measuring temperature distribution of an optical fiber, which enables an optical pulse to be incident on an optical fiber and measures temperature distribution in units of spatial resolution regions based on return light from the optical fiber, the method comprising:

calculating a temperature difference between corresponding spatial resolution areas based on a first temperature distribution obtained by return light from a first optical fiber section laid along the roller row and a second temperature distribution obtained by return light from a second optical fiber section laid side by side with the first optical fiber section at a position farther from the roller row than the first optical fiber section;

calculating, for each spatial resolution region, a temperature difference for evaluation, the temperature difference for evaluation being a difference between a first temperature of each spatial resolution region and a sum of first temperatures of adjacent spatial resolution regions and a difference between a second temperature of each spatial resolution region and a sum of second temperatures of adjacent spatial resolution regions; and

When the calculated temperature difference for evaluation exceeds the reference value, it is determined that an abnormality has occurred in the roller near the spatial resolution area.

According to the present invention, it is possible to provide an optical fiber temperature distribution measurement system and an optical fiber temperature distribution measurement method capable of easily detecting roller abnormalities of a belt conveyor through a simple operation of laying an optical fiber.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a block diagram depicting the configuration of a roller abnormality detection system for a belt conveyor configured using an optical fiber temperature distribution measurement system according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram illustrating calculation of a temperature difference and calculation of a temperature difference for evaluation.

3A and 3B are diagrams explaining the addition of spatial resolution areas adjacent to each other.

FIG4 is a flow chart depicting the operation of the optical fiber temperature distribution measurement system.

FIG5 is a block diagram depicting another configuration of the roller abnormality detection system.

FIG6 is a diagram illustrating calculation of the second temperature distribution.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a block diagram illustrating a configuration of a roller abnormality detection system 10 for a belt conveyor configured using an optical fiber temperature distribution measurement system 100 according to an exemplary embodiment of the present invention.

As shown in FIG1 , a fiber-optic temperature distribution measurement system 100 configured to detect abnormalities in rollers 320 of a belt conveyor 310 includes a fiber-optic temperature distribution measurement module 110 and a data processor 120. The fiber-optic temperature distribution measurement system 100 is particularly advantageous for detecting abnormalities in rollers 320 of the belt conveyor 310. However, it can also be applied to detecting abnormalities in roller rows for other purposes.

Here, a plurality of rollers 320 are supported by metal roller support columns 321 and arranged at intervals of 1 m along the conveying direction of the belt conveyor 310, thereby forming a roller row. The temperature of the roller 320 that is rotating abnormally increases due to friction at the contact portion with the bearing part or the belt conveyor 310.

The fiber optic temperature distribution measurement module 110 can be configured using, for example, a fiber optic temperature distribution measurement device (DTS: Distributed Temperature Sensor). In the fiber optic temperature distribution measurement module 110, spatial resolution, which is a unit of length related to temperature detection, is defined as a standard. The spatial resolution is typically approximately 1 m and may vary depending on the length of the optical path.

The data processor 120 has a temperature distribution calculator 121, a temperature difference calculator 122, and an abnormality detector 123, and can be configured using an information processing device such as a PC in which application software developed as a tool for the optical fiber temperature distribution measuring apparatus has been installed.

The optical fiber temperature distribution measurement system 100 is configured to measure temperature distribution by using Raman scattered light, which is backscattered light generated when pulsed light is incident on an optical fiber and is highly temperature-dependent. Raman scattered light includes anti-Stokes light generated on the short wavelength side of the optical pulse wavelength and Stokes light generated on the long wavelength side, and the intensity ratio of these light intensity ratios changes in proportion to temperature changes.

In the optical fiber temperature distribution measurement system 100 , the optical fiber temperature distribution measurement module 110 and the temperature distribution calculator 121 of the data processor 120 are configured to perform the same operations as those in the prior art.

Specifically, the fiber temperature distribution measurement module 110 is configured to repeatedly inject pulsed light into an optical fiber laid along the measurement target and measure the temporal variations in the intensity of Stokes and anti-Stokes light relative to the pulsed light. The temporal variations in the intensity of Stokes and anti-Stokes light correspond to the locations along the optical fiber path where backscattered light is generated. Therefore, the temperature distribution calculator 121 is configured to calculate the temperature distribution of the measurement target based on the measurement results of the fiber temperature distribution measurement module 110.

In the exemplary embodiment, optical fiber 210 is laid along the row of rollers to be measured. However, as shown in FIG1 , the optical fiber is laid in a loop, forming a first optical fiber section 211 close to the row of rollers and a second optical fiber section 212 farther from the row of rollers than first optical fiber section 211. First optical fiber section 211 measures the temperature of rollers 320, while second optical fiber section 212 measures the ambient temperature near rollers 320. First optical fiber section 211 and second optical fiber section 212 are laid straight and parallel to the row of rollers, with equal distances from each roller 320.

Optical fiber 210 is laid so that first optical fiber portion 211 is positioned near metal roller support column 321, where it can detect a temperature increase of roller 320. A distance (e.g., 20 to 30 cm) within which second optical fiber portion 212 is unaffected by the temperature increase of roller 320 is ensured. That is, there is no need to coil optical fiber 210 or bring it into close contact with metal roller support column 321. Therefore, optical fiber 210 can be laid simply, reducing the labor involved in laying the optical fiber and suppressing any cost increases.

The temperature difference calculator 122 of the data processor 120 is configured to calculate the temperature difference between corresponding spatial resolution areas based on the first temperature distribution to be obtained by the return light from the first optical fiber portion 211 and the second temperature distribution to be obtained by the return light from the second optical fiber portion 212.

Herein, a spatial resolution region is a temperature measurement area defined by spatial resolution. That is, a measured temperature is obtained for each spatial resolution region. Furthermore, corresponding spatial resolution regions are those that can be considered to be located at the same position in the roll direction of the first and second optical fiber sections 211 and 212 laid side by side. Since the positions of the two ends of the roll can be easily specified in the temperature distribution of the measurement results, corresponding spatial resolution regions can also be easily specified.

The temperature difference is a value indicating how much higher the measured temperature of the first optical fiber portion 211 is relative to the measured temperature of the second optical fiber portion 212 in the corresponding spatial resolution region. It is assumed that the influence of the surrounding environment, such as sunlight and wind, is substantially the same in the corresponding spatial resolution region. Therefore, the temperature difference is considered to be caused by radiant heat caused by the temperature increase of the roller 320, and the influence of various interferences can be excluded.

However, the temperature increase of roller 320 due to an abnormality is localized and averaged within the spatial resolution area. Therefore, the value represented by the temperature difference is small and difficult to detect. Furthermore, if an abnormality occurs in roller 320 whose installation position straddles both spatial resolution areas, the temperature increase is dispersed across both spatial resolution areas. Consequently, the temperature difference is further reduced, making it difficult to detect.

Therefore, as shown in Figure 2, abnormality detector 123 is configured to calculate a temperature difference for evaluation for each spatial resolution area. This temperature difference is the sum of the temperature difference for each spatial resolution area and the temperature differences of the spatial resolution areas preceding and following each resolution area in the roller travel direction. When the calculated temperature difference for evaluation exceeds a reference value, it is determined that an abnormality has occurred in the roller near that spatial resolution area.

The above configuration is based on the fact that even when the temperature rises within a specific spatial resolution area, due to the definition of spatial resolution, part of the temperature rise appears as a temperature rise in adjacent spatial resolution areas, as shown in Figure 3A. The temperature rise that appears in adjacent spatial resolution areas is smaller. However, when the sum is calculated, the temperature rise in the spatial resolution area where the temperature actually rose is emphasized. This allows accurate detection of the localized, small temperature rise caused by abnormal roller 320.

Furthermore, using the sum of temperature differences between adjacent spatial resolution areas, as shown in FIG. 3B , even when the abnormal roller 320 spans two spatial resolution areas and the temperature increase is dispersed within each spatial resolution area, evaluation can be performed using the summed temperature increase.

Subsequently, the operation of the optical fiber temperature distribution measurement system 100 of the exemplary embodiment will be described with reference to the flowchart of FIG. 4 .

First, the temperature distribution calculator 121 calculates a first temperature distribution based on the return light of the first optical fiber portion 211 ( S101 ), and also calculates a second temperature distribution based on the return light of the second optical fiber portion 212 ( S102 ).

Then, the temperature difference calculator 122 calculates the temperature difference between the corresponding spatial resolution areas based on the first temperature distribution and the second temperature distribution ( S103 ).

After calculating the temperature difference, the abnormality detector 123 calculates a temperature difference for evaluation for each spatial resolution region, the temperature difference for evaluation being the sum of the temperature difference of each spatial resolution region and the temperature difference of an adjacent spatial resolution region ( S104 ).

Then, it is determined whether there is a spatial resolution area where the calculated temperature difference for evaluation exceeds a predetermined reference value (S105). When it is determined that there is a spatial resolution area where the calculated temperature difference for evaluation exceeds a predetermined reference value, it is determined that an abnormality has occurred in the roller 320 near the spatial resolution area (S106).

Through the above operations, the optical fiber temperature distribution measurement system 100 can detect abnormalities in the roller 320 .

In the above embodiment, the first optical fiber portion 211 and the second optical fiber portion 212 are configured by forming a single optical fiber 210 into a loop. This allows the measurement time for the first temperature distribution and the second temperature distribution to be the same, enhancing interference removal and noise immunity through bidirectional measurement. However, the first optical fiber portion 211 and the second optical fiber portion 212 may also be formed from two independent optical fibers.

In the above embodiment, the temperature difference is calculated for each spatial resolution area and added to the temperature differences of adjacent spatial resolution areas to calculate the temperature difference used for evaluation. However, the temperature difference used for evaluation can also be calculated by adding the measured temperatures of adjacent spatial resolution areas and then calculating the temperature difference for each spatial resolution area.

In addition, when the ambient temperature is stable, the optical fiber 210 can be composed of only the first optical fiber portion 211, and the second optical fiber portion 212 can be omitted, as shown in Figure 5. This can further simplify the work of laying the optical fiber and save costs.

In the above-described modified configuration, the second temperature distribution of each spatial resolution region is estimated using the first temperature distribution of the spatial resolution regions other than the adjacent spatial resolution regions. For example, as shown in FIG6 , the second temperature distribution is estimated based on the average of the measured temperatures of the preceding and following spatial resolution regions, which are two regions apart. Furthermore, the second temperature distribution can be estimated using the temperatures of other spatial resolution regions, since these other spatial resolution regions are spatial resolution regions other than the adjacent spatial resolution regions. For example, the second temperature distribution can be estimated using one of the preceding and following spatial resolution regions, or based on the average of multiple spatial resolution regions.

Claims (6)

1. An optical fiber temperature distribution measurement system configured such that an optical pulse can be incident on an optical fiber and temperature distribution is measured in spatial resolution regions based on the return light from the optical fiber, the system comprising: A temperature difference calculator is configured to calculate the temperature difference between corresponding spatial resolution regions based on a first temperature distribution and a second temperature distribution. The first temperature distribution is obtained from return light from a first optical fiber section laid along a roller, and the second temperature distribution is obtained from return light from a second optical fiber section laid parallel to the first optical fiber section at a position farther from the roller than the first optical fiber section. An anomaly detector is configured to calculate a temperature difference for evaluation for each spatial resolution region, and to determine that an anomaly has occurred in the roller near the spatial resolution region when the calculated temperature difference for evaluation exceeds a reference value. The temperature difference for evaluation is the sum of the temperature difference of each spatial resolution region and the temperature difference of its adjacent spatial resolution regions. 2. An optical fiber temperature distribution measurement system configured such that an optical pulse can be incident on an optical fiber and the temperature distribution is measured in spatial resolution regions based on the return light from the optical fiber, the system comprising: A temperature difference calculator is configured to calculate the temperature difference between corresponding spatial resolution regions based on a first temperature distribution and a second temperature distribution, the first temperature distribution being obtained from return light from an optical fiber section laid along a roller, and the second temperature distribution being calculated based on the temperatures of spatial resolution regions in the first temperature distribution excluding adjacent spatial resolution regions; and An anomaly detector is configured to calculate a temperature difference for evaluation for each spatial resolution region, and to determine that an anomaly has occurred in the rollers included in the spatial resolution region when the calculated temperature difference for evaluation exceeds a reference value. The temperature difference for evaluation is the sum of the temperature difference of each spatial resolution region and the temperature difference of its adjacent spatial resolution regions. 3. An optical fiber temperature distribution measurement system configured such that an optical pulse can be incident on an optical fiber and the temperature distribution is measured in spatial resolution regions based on the return light from the optical fiber, the system comprising: The data processor is configured to: The temperature distributions of a first temperature and a second temperature are calculated. The first temperature distribution is obtained from the return light from a first optical fiber section laid along the roller, and the second temperature distribution is obtained from the return light from a second optical fiber section laid parallel to the first optical fiber section at a position farther from the roller than the first optical fiber section. For each spatial resolution region, a temperature difference for evaluation is calculated. This temperature difference is the difference between a first temperature of each spatial resolution region and the sum of the first temperatures of its adjacent spatial resolution regions, and between a second temperature of each spatial resolution region and the sum of the second temperatures of its adjacent spatial resolution regions. When the calculated temperature difference used for evaluation exceeds the reference value, it is determined that an anomaly has occurred in the roller near the spatial resolution region. 4. The fiber optic temperature distribution measurement system according to any one of claims 1 to 3, wherein the rollers are rollers of a belt conveyor. 5. The fiber optic temperature distribution measurement system according to any one of claims 1 or 3, wherein the first fiber portion and the second fiber portion are configured by forming a single fiber into a loop. 6. A method for measuring temperature distribution in an optical fiber, wherein an optical pulse is incident on the optical fiber and the temperature distribution is measured in units of spatial resolution regions based on the return light from the optical fiber, the method comprising: The temperature difference between corresponding spatial resolution regions is calculated based on a first temperature distribution and a second temperature distribution. The first temperature distribution is obtained by the return light from a first optical fiber section laid along the roller, and the second temperature distribution is obtained by the return light from a second optical fiber section laid parallel to the first optical fiber section at a position farther from the roller than the first optical fiber section. For each spatial resolution region, a temperature difference for evaluation is calculated, wherein the temperature difference for evaluation is the difference between a first temperature of each spatial resolution region and the sum of the first temperatures of its adjacent spatial resolution regions, and between a second temperature of each spatial resolution region and the sum of the second temperatures of its adjacent spatial resolution regions; and When the calculated temperature difference used for evaluation exceeds the reference value, it is determined that an anomaly has occurred in the roller near the spatial resolution region.