US-12625069-B2 - Gas concentration measuring device, gas concentration measuring method, and program

Abstract

To accurately estimate a feature quantity related to a gas concentration and accurately measure a gas concentration in a space even in a case where a background temperature changes due to a factor other than gas. A gas concentration measuring device 20 includes an inspection image acquisition unit 211 that acquires infrared image time-series data captured by an infrared camera 10 , a pixel specifying unit 2121 that specifies a target pixel for gas concentration measurement and a reference pixel with a gas concentration lower than a gas concentration of the target pixel in the infrared image, a without-gas background temperature estimation unit 2122 that estimates without-gas background temperature time-series infrared data in the target pixel based on target pixel time-series infrared data and reference pixel time-series infrared data in time-series data of the infrared image, and a concentration-feature-quantity calculation unit 2123 that calculates time-series data of a feature quantity related to a gas concentration of the target pixel based on the target pixel time-series infrared data and without-gas background temperature time-series infrared data of the target pixel.

Inventors

• Motohiro Asano

Assignees

• Konica Minolta, Inc.

Dates

Publication Date

20260512

Application Date

20220823

Priority Date

20211210

Claims (19)

1. 1 . A gas concentration measuring device that measures a distribution of a gas concentration in a space as a monitoring target, the gas concentration measuring device comprising: an inspection image acquisitor that acquires infrared image time-series data in which infrared images captured by an infrared camera at a plurality of times and capturing the space constituted by a plurality of pixels are arranged in time series; a pixel specifier that specifies a target pixel for gas concentration measurement and a reference pixel with a gas concentration lower than a gas concentration of the target pixel in the infrared image; a without-gas background temperature estimator that estimates without-gas background temperature time-series infrared data in the target pixel based on target pixel time-series infrared data in which infrared data of the target pixel is arranged in time series and reference pixel time-series infrared data in which infrared data of the reference pixel is arranged in time series in time-series data of the infrared image; and a concentration-feature-quantity calculator that calculates time-series data of a feature quantity related to a gas concentration of the target pixel based on the target pixel time-series infrared data and without-gas background temperature time-series infrared data of the target pixel.
2. 2 . The gas concentration measuring device according to claim 1 , wherein the pixel specifier generates time-series data of a gas cloud image obtained by extracting an image of a gas cloud from time-series data of the infrared image, and specifies the target pixel and the reference pixel based on time-series data of the gas cloud image.
3. 3 . The gas concentration measuring device according to claim 2 , wherein time-series data of the gas cloud image is time-series data of an image obtained by extracting a temporal change in a specific frequency component from time-series data of the infrared image.
4. 4 . The gas concentration measuring device according to claim 3 , wherein the without-gas background temperature estimator estimates the without-gas background temperature time-series infrared data in the target pixel by drawing, for the target pixel time-series infrared data, an envelope in a manner that a sum of areas of regions sandwiched between the target pixel time-series infrared data and the envelope is minimized.
5. 5 . The gas concentration measuring device according to claim 2 , wherein the without-gas background temperature estimator estimates the without-gas background temperature time-series infrared data in the target pixel by drawing, for the target pixel time-series infrared data, an envelope in a manner that a sum of areas of regions sandwiched between the target pixel time-series infrared data and the envelope is minimized.
6. 6 . The gas concentration measuring device according to claim 1 , wherein the infrared image includes data indicating a luminance or a temperature.
7. 7 . The gas concentration measuring device according to claim 6 , wherein the without-gas background temperature estimator estimates the without-gas background temperature time-series infrared data in the target pixel by drawing, for the target pixel time-series infrared data, an envelope in a manner that a sum of areas of regions sandwiched between the target pixel time-series infrared data and the envelope is minimized.
8. 8 . The gas concentration measuring device according to claim 1 , wherein the pixel specifier selects the reference pixel from pixels with a value of an infrared image within a predetermined range with respect to the target pixel.
9. 9 . The gas concentration measuring device according to claim 8 , wherein the without-gas background temperature estimator estimates the without-gas background temperature time-series infrared data in the target pixel by drawing, for the target pixel time-series infrared data, an envelope in a manner that a sum of areas of regions sandwiched between the target pixel time-series infrared data and the envelope is minimized.
10. 10 . The gas concentration measuring device according to claim 1 , wherein the without-gas background temperature estimator estimates the without-gas background temperature time-series infrared data in the target pixel by drawing, for the target pixel time-series infrared data, an envelope in a manner that a sum of areas of regions sandwiched between the target pixel time-series infrared data and the envelope is minimized.
11. 11 . The gas concentration measuring device according to claim 10 , wherein the envelope is a line obtained by changing a change amount and/or an offset value of the reference pixel time-series infrared data.
12. 12 . The gas concentration measuring device according to claim 10 , wherein the envelope is an envelope with a larger temperature difference from a gas temperature in the space out of two envelopes that can be drawn in target pixel time-series infrared data.
13. 13 . The gas concentration measuring device according to claim 11 , wherein the envelope is an envelope with a larger temperature difference from a gas temperature in the space out of two envelopes that can be drawn in target pixel time-series infrared data.
14. 14 . A gas concentration measuring device that measures a distribution of a gas concentration in a space as a monitoring target, the gas concentration measuring device comprising: an inspection image acquisitor that acquires infrared image time-series data in which infrared images captured by an infrared camera at a plurality of times and capturing the space constituted by a plurality of pixels are arranged in time series; a pixel specifier that specifies a target pixel for gas concentration measurement and a reference pixel with a gas concentration lower than a gas concentration of the target pixel in the infrared image; and a concentration-feature-quantity calculator that calculates a feature quantity related to a gas concentration of the target pixel based on target pixel temperature information including a temperature change of target pixel time-series infrared data in which infrared data of the target pixel is arranged in time series and reference pixel temperature information including a temperature change of reference pixel time-series infrared data in which infrared data of the reference pixel is arranged in time series in time-series data of the infrared image.
15. 15 . A gas concentration measuring method of measuring a distribution of a gas concentration in a space as a monitoring target, the gas concentration measuring method comprising: acquiring infrared image time-series data in which infrared images captured by an infrared camera at a plurality of times and capturing the space constituted by a plurality of pixels are arranged in time series; specifying a target pixel for gas concentration measurement and a reference pixel with a gas concentration lower than a gas concentration of the target pixel in the infrared image; estimating without-gas background temperature time-series infrared data in the target pixel based on target pixel time-series infrared data in which infrared data of the target pixel is arranged in time series and reference pixel time-series infrared data in which infrared data of the reference pixel is arranged in time series in time-series data of the infrared image; and calculating time-series data of a feature quantity related to a gas concentration of the target pixel based on target pixel time-series infrared data and without-gas background temperature time-series infrared data of the target pixel.
16. 16 . The gas concentration measuring method according to claim 15 , wherein in specifying the target pixel and the reference pixel, time-series data of a gas cloud image obtained by extracting an image of a gas cloud from time-series data of the infrared image is generated, and the target pixel and the reference pixel are specified based on time-series data of the gas cloud image.
17. 17 . The gas concentration measuring method according to claim 16 , wherein in estimating the without-gas background temperature, the without-gas background temperature time-series infrared data in the target pixel is estimated by drawing, for the target pixel time-series infrared data, an envelope in a manner that a sum of areas of regions sandwiched between the target pixel time-series infrared data and the envelope is minimized.
18. 18 . The gas concentration measuring method according to claim 15 , wherein in estimating the without-gas background temperature, the without-gas background temperature time-series infrared data in the target pixel is estimated by drawing, for the target pixel time-series infrared data, an envelope in a manner that a sum of areas of regions sandwiched between the target pixel time-series infrared data and the envelope is minimized.
19. 19 . A non-transitory recording medium storing a computer readable program that causes a computer to perform gas concentration measuring processing of measuring a distribution of a gas concentration in a space as a monitoring target, wherein the gas concentration measuring processing includes acquiring infrared image time-series data in which infrared images captured by an infrared camera at a plurality of times and capturing the space constituted by a plurality of pixels are arranged in time series, specifying a target pixel for gas concentration measurement and a reference pixel with a gas concentration lower than a gas concentration of the target pixel in the infrared image, estimating without-gas background temperature time-series infrared data in the target pixel based on target pixel time-series infrared data in which infrared data of the target pixel is arranged in time series and reference pixel time-series infrared data in which infrared data of the reference pixel is arranged in time series in time-series data of the infrared image, and calculating time-series data of a feature quantity related to a gas concentration of the target pixel based on target pixel time-series infrared data and without-gas background temperature time-series infrared data of the target pixel.

Description

TECHNICAL FIELD The present disclosure relates to a gas concentration measuring device, a gas concentration measuring method, and a program, and relates to gas concentration measurement using an infrared captured image. BACKGROUND ART In facilities that use gases (hereinafter, also referred to as “gas facilities”), such as production facilities that produce natural gas and oil, production plants that produce chemical products using gases, gas pipe transmission facilities, petrochemical plants, thermal power plants, and iron and steel facilities, risks of gas leakage due to aged deterioration and operational errors of the facilities have been recognized, and a gas detection device is provided to minimize the gas leakage. Regarding the gas detection, in addition to a gas detection device using a fact that electrical characteristics of a detection probe are changed by contact of gas molecules with the detection probe, an optical gas leakage detection method has been adopted in which an infrared moving image is captured using infrared absorption characteristics of gas to detect gas leakage in an inspection region in recent years. Since the gas detection method by the infrared moving image can visualize the gas by the image, the method has an advantage that an emission state of a flow of the gas or the like and a leakage position can be easily detected as compared with the conventional detection probe method. In addition, since the state of the leaked gas is recorded as the image, the method has an advantage that the image can be used as evidence of occurrence of gas leakage and restoration thereof. As this type of infrared gas detection device, for example, Patent Literature 1 discloses a technique of estimating a concentration length product by specifying a background temperature when gas is present and the background temperature when gas is not present by detecting an amplitude characteristic in a time-series luminance change for each pixel to be inspected in an infrared image obtained by capturing a monitoring target. This technique uses the fact that with-gas data and without-gas data is captured when the pixels to be inspected are viewed in time series due to the property of gas fluctuation. CITATION LIST Patent Literature Patent Literature 1: WO 2017/104617 A1 SUMMARY OF INVENTION Technical Problem However, in the measurement device described in Patent Literature 1, for example, when the background temperature changes due to factors other than gas, such as the influence of the cloud, the temperature change due to the gas may be smaller than the change in the background temperature, and there is a problem that it is difficult to accurately estimate the feature quantity related to the gas concentration such as the concentration length product and accurately measure the gas concentration in the space. An aspect of the present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a gas concentration measuring device, a gas concentration measuring method, and a program capable of accurately measuring a gas concentration in a space from an infrared moving image even in a case where a background temperature changes due to a factor other than gas. Solution to Problem A gas concentration measuring device according to one aspect of the present disclosure is a gas concentration measuring device that measures a distribution of a gas concentration in a space exposed from a gas leakage monitoring target, the gas concentration measuring device including an inspection image acquisition unit that acquires infrared image time-series data in which infrared images captured by an infrared camera at a plurality of times and capturing the space constituted by a plurality of pixels are arranged in time series, a pixel specifying unit that specifies a target pixel for gas concentration measurement and a reference pixel with a gas concentration lower than a gas concentration of the target pixel in the gas cloud image, a without-gas background temperature estimation unit that estimates without-gas background temperature time-series infrared data in the target pixel based on target pixel time-series infrared data in which infrared data of the target pixel is arranged in time series and reference pixel time-series infrared data in which infrared data of the reference pixel is arranged in time series in time-series data of the infrared image, and a concentration-feature-quantity calculation unit that calculates time-series data of a feature quantity related to a gas concentration of the target pixel based on the target pixel time-series infrared data and without-gas background temperature time-series infrared data of the target pixel. Advantageous Effects of Invention According to the gas concentration measuring device, the gas concentration measuring method, and the program of one aspect of the present disclosure, it is possible to more accurately estimate the background tempera