High-temperature source point detection method and system in closed space smog environment

Abstract

The invention belongs to the field of high-temperature source point detection, and particularly discloses a high-temperature source point detection method and system in a closed space smog environment, and the method comprises the steps: obtaining an infrared radiation image of a closed space monitoring region, and determining the position of a high-temperature source point in a closed space based on the infrared radiation image; the method comprises the following steps: acquiring an infrared radiation image of an infrared band of 10-12 [mu] m for a closed space in which steam leakage occurs; and acquiring an infrared radiation image of an infrared band of more than 80 microns for the closed space in which the fire breaks out. Appropriate infrared detection wave bands are selected according to different conditions to obtain clear and high-quality high-temperature source point radiation imaging images, and the influence on high-temperature source point detection due to the fact that personnel cannot reach shielding media such as smoke in a closed space under the industrial factory building scale is avoided; therefore, the position of the high-temperature source point is obtained through accurate inversion, and a solid technical foundation is laid for fire suppression in a closed space and industrial pipeline leakage emergency repair.

Description

Technical Field

[0001] The present invention belongs to the field of high temperature source point detection, and more specifically, relates to a method and system for detecting high temperature source points in a closed space smoke environment. Background Art

[0002] In terms of industrial plant fires. With the continuous deepening of human urbanization, the three-dimensional spatial structure, physical properties and functions of large modern buildings such as high-rise residential buildings, underground shopping malls, hospitals, museums, libraries and airports are becoming increasingly complex. They show the characteristics of high-rise, large scale, diversity and comprehensiveness. Coupled with high population density and special requirements for equipment, facilities and decoration, indoor fire hazards, fire loads and indoor emergency evacuation difficulties have increased sharply. Efficient and reliable indoor fire monitoring methods have become the focus of research in the field of public safety at home and abroad. In recent years, indoor sensing technology has developed rapidly. Various sensors are arranged indoors and outdoors in large modern buildings, which can sense and monitor indoor environmental changes in real time, monitor indoor fire conditions to achieve dynamic optimization of indoor fire evacuation routes. Commonly used indoor fire monitoring sensors include heat detection sensors, temperature sensors, smoke sensors and gas detection sensors. In the case of indoor fire, the indoor fire monitoring sensor network composed of multi-source sensors can sense the changes in fire conditions in real time during the whole process of fire, such as changes in the state of indoor space structure (fire protection system), location of fire source, fire development trend (dynamic distribution information of intensity and temperature, etc.), location and distribution of personnel, etc.

[0003] In terms of high-temperature steam leakage detection in industrial power plants. One is based on optical detection methods, using infrared thermal imaging cameras to obtain monitoring images, and using image processing technology to monitor steam leakage locations at the edge, and identify the exact location of steam leakage points in plant equipment. The second is based on acoustic detection methods. When steam leaks in the pipeline, the high pressure difference between the inner and outer pipelines will cause the release of elastic energy. This process causes gas to be injected into the outer space at high speed, while generating sound vibrations along the pipeline, establishing the relationship between the flow rate and sound energy caused by gas leakage, and forming a pipeline leakage detection model based on acoustic technology. However, the acoustic method still has limitations, and sound waves are greatly affected by environmental noise. When the environmental noise is relatively large, the steam leakage location cannot be accurately located.

[0004] The current optical and acoustic methods used to detect high-temperature sources such as fire or steam in enclosed spaces at the scale of industrial plants have limitations. Usually, when there is a fire or high-temperature steam leak, there will be obvious smoke or fog. How to avoid the influence of masking media such as smoke on the detection of high-temperature sources and obtain high-quality source imaging images is of great significance to improving the accuracy of source position measurement. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a method and system for detecting high temperature source points in a closed space smoke environment, the purpose of which is to accurately determine the location of high temperature source points in an environment with masking media such as smoke.

[0006] To achieve the above object, according to one aspect of the present invention, a method for detecting high temperature source points in a closed space smoke environment is proposed, comprising the following steps:

[0007] Acquire an infrared radiation image of the monitoring area of ​​the enclosed space, and determine the location of the high temperature source point in the enclosed space based on the infrared radiation image;

[0008] Among them, for closed spaces where steam leakage occurs, infrared radiation images in the 10μm to 12μm infrared band are obtained; for closed spaces where fire occurs, infrared radiation images in the 80μm and above infrared bands are obtained.

[0009] As a further preference, for the closed space where steam leakage occurs, an infrared radiation image in the 11 μm infrared band is acquired.

[0010] As a further preferred embodiment, for the enclosed space where the fire occurs, an infrared radiation image in the 80 μm infrared band is acquired.

[0011] As a further preference, at least one pair of camera units is arranged in the closed space for acquiring infrared radiation images of the monitoring area of ​​the closed space; the detection directions of the two camera units in each pair of camera units are perpendicular to each other, and ensure that the monitoring area is within the field of view of the camera units.

[0012] As a further preference, a beam splitter is arranged in front of the lens of the camera unit for adjusting the infrared detection band.

[0013] As a further preference, the corresponding directional radiation intensities are calculated respectively based on the infrared radiation images acquired by a pair of camera units, so as to determine the specific position of the high temperature source point in the closed space.

[0014] As a further preference, an inverse Monte Carlo method is used to analyze the infrared radiation image to obtain the corresponding directional radiation intensity.

[0015] According to another aspect of the present invention, a detection system for implementing the above-mentioned high temperature source point detection method in a closed space smoke environment is provided, comprising a camera unit and an information unit, wherein:

[0016] The camera unit is arranged in the closed space and is used to collect the video of the monitoring area in real time and obtain the infrared radiation image of the monitoring area when a fire or steam leakage occurs;

[0017] The information unit is arranged outside the closed space and is connected to the imaging unit, and is used to determine the location of the high temperature source point according to the infrared radiation image acquired by the imaging unit.

[0018] As a further preference, a monitoring station is also included for displaying the video and infrared radiation images acquired by the camera unit in real time, and issuing an audible and visual alarm when a fire or steam leakage occurs.

[0019] As a further preferred embodiment, a storage unit is further included for storing the video acquired by the camera unit, and the video stored in the storage unit can be retrieved by the monitoring station at a later time.

[0020] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0021] 1. Based on the attenuation law of infrared radiation signals of different bands in smoke environment, the present invention selects appropriate infrared detection bands for different situations to obtain clear and high-quality high-temperature source radiation imaging images, avoiding the influence of smoke and other shielding media on high-temperature source detection in closed spaces that are inaccessible to personnel at the scale of industrial plants; and then accurately inverts and obtains the position of the high-temperature source, laying a solid technical foundation for fire fighting in closed spaces and emergency repair of industrial pipeline leaks.

[0022] 2. The detection of high-temperature source points in a closed space at the scale of an industrial plant belongs to the detection of high-temperature source points in a larger volume system. Taking into account factors such as error and time efficiency, the present invention uses the inverse Monte Carlo method to calculate the directional radiation intensity, which can more effectively perform radiation image analysis and realize real-time inversion and reconstruction of high-temperature source points in closed spaces.

[0023] 3. The detection system of the present invention solves the problem of failure of traditional video surveillance systems in smoke environments, and establishes a real-time temperature monitoring system for enclosed spaces that are inaccessible to personnel at the scale of industrial plants, with functions such as data storage, historical image playback, and real-time alarm for fire and steam leaks. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of a high temperature source point detection system in a closed space smoke environment according to an embodiment of the present invention;

[0025] Figure 2 (a) and (b) are schematic diagrams showing the variation of the extinction coefficient and infrared transmittance of smoke with wavelength when a fire occurs in an embodiment of the present invention;

[0026] Figure 3 (a) and (b) are schematic diagrams of the change in water mist volume percentage at different geometric mean radii and geometric standard deviations in the embodiments of the present invention;

[0027] Figure 4(a)-(c) are schematic diagrams showing the effects of different geometric mean radii, geometric standard deviations, and water mist volume fractions on the extinction coefficient in the embodiments of the present invention;

[0028] Figure 5 (a)-(d) are schematic diagrams of the change in water mist transmittance at different geometric mean radii, geometric standard deviations, water mist volume fractions, and detection distances according to the embodiments of the present invention.

[0029] In all the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 - camera unit, 2 - information unit, 3 - storage unit, 4 - display unit, 5 - monitoring station. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] An embodiment of the present invention provides a method for detecting a high temperature source in a closed space smoke environment, comprising the following steps:

[0032] An infrared radiation image of the monitoring area of ​​the enclosed space is obtained, and the location of the high temperature source point in the enclosed space is determined based on the infrared radiation image.

[0033] Specifically:

[0034] (1) Since there will be obvious smoke or fog in the event of a fire or high-temperature steam leak, how to avoid the influence of smoke and other shielding media on the detection of high-temperature source points and obtain high-quality source point imaging images is of great significance to improving the accuracy of source point position measurement. In view of the different smoke environments during steam leaks / fires, by analyzing the attenuation law of the smoke environment on infrared radiation signals of different bands, the following designs are designed:

[0035] For the closed space where steam leakage occurs, obtain infrared radiation images in the infrared band of 10μm to 12μm, preferably 11μm;

[0036] For the enclosed space where the fire occurs, infrared radiation images in the infrared band above 80μm are obtained; preferably 80μm.

[0037] (2) At least one pair of camera units is set in the enclosed space to obtain infrared radiation images of the monitoring area of ​​the enclosed space; the detection directions of the two camera units in each pair of camera units are perpendicular to each other, and it is ensured that the monitoring area is within the viewing angle of the camera unit. A spectroscope is set in front of the lens of the camera unit to determine the infrared detection band.

[0038] (3) Real-time and efficient inversion of high-temperature source points in closed spaces based on infrared radiation image processing. The detection of high-temperature source points in closed spaces at the scale of industrial plants belongs to the detection of high-temperature source points in a large volume system. Taking into account factors such as error and time efficiency, the inverse Monte Carlo method is used to calculate the directional radiation intensity of unstructured grids, which is used to solve the radiation intensity in the direction corresponding to the pixel viewing angle of the camera unit and establish the relationship between the medium emission and the radiation image. Due to the high resolution of the camera and the small field of view of a single pixel, the inverse Monte Carlo method can perform radiation image analysis more effectively than other methods, and can complete the real-time inversion and reconstruction of high-temperature source points in closed spaces.

[0039] Specifically, since the detection directions of a pair of camera units are perpendicular to each other, after obtaining the directional radiation intensity respectively, the temperature field of the monitored space can be reconstructed in three dimensions by using the calibrated correspondence between the pixel position of the infrared radiation image and the actual spatial position, thereby determining the three-dimensional spatial position of the high temperature source point based on the point with the maximum radiation intensity.

[0040] When multiple pairs of camera units are provided, the position of the high-temperature source point in the monitoring space can be repeatedly calibrated and calculated, thereby further improving the accuracy of the acquired position of the high-temperature source point.

[0041] The embodiment of the present invention provides a high temperature source detection system in a closed space smoke environment. Figure 1 As shown, it includes a camera unit 1, a monitoring station 5, an information unit 2 and a storage unit 3, wherein:

[0042] The camera unit is arranged in the closed space, and the monitoring station, the information unit and the storage unit are arranged in a control room outside the closed space;

[0043] The camera unit is used to collect the video of the monitoring area in real time, and obtain the infrared radiation image of the monitoring area when a fire or steam leak occurs. The information unit is connected to the camera unit through a cable, and is used to determine the location of the high temperature source point based on the infrared radiation image obtained by the camera unit; the monitoring station is used to display the video and infrared radiation image obtained by the camera unit in real time, and issue an audible and visual alarm when a fire or steam leak occurs. The storage unit is used to save the video obtained by the camera unit, and the video saved in the storage unit can be retrieved by the monitoring station later.

[0044] Specifically, during normal operation, the camera unit collects real-time video of the monitored area and transmits it to the information unit, storage unit and display unit 4 of the monitoring station for real-time display; when steam leaks after a fire occurs in the closed space of an industrial plant, a clear image is obtained by the selected infrared detection band camera unit, and the corresponding calibration relationship between the image pixel position and the actual spatial position is obtained by the camera unit. The information unit obtains the accurate positioning of the high-temperature source point in the monitored space through software algorithm inversion. When a fire and steam leakage occur, the monitoring station sends out an audible and visual alarm, providing technical support for the next step of fire fighting and equipment pipeline leakage repair; the video data in the storage unit is retrieved through the display unit of the monitoring station, laying the foundation for the investigation and review of fire and steam leakage accidents.

[0045] In order to prove the effectiveness of the infrared detection band proposed by the present invention, the following specific examples are used for illustration:

[0046] (1) Regarding the problem of fire point detection in smoke environment:

[0047] Take the burning of indoor PVC cables as an example, assuming that the burning occurs in a closed space of 5m×5m×3m. When PVC cables burn, they mainly produce carbon particles. Assuming that a total of 220g of cables burn in the closed space, 120g of smoke can be produced, and its number density is 3100 particles / cm 3 The particle size of carbon particles is between 1 and 100 microns, and it is assumed here that the particle size is 10 microns.

[0048] The Mie theory is used to calculate the variation of the extinction coefficient and infrared transmittance of the smoke with wavelength. Figure 2 It can be clearly seen that the infrared transmittance increases with the increase of wavelength, so the detection wavelength should be set at 80 microns or longer to obtain better results. In addition, when the extinction coefficient is small, since the wavelength multiplied by the temperature is a constant, in order to further improve the accuracy of monitoring the position of high-temperature points in space, the detection wavelength is better at 80 microns.

[0049] (2) Detection of high-temperature steam leakage in foggy environments:

[0050] First, the parameters that affect the droplet size distribution are studied. In general, the droplet size satisfies the normal distribution.

[0051]

[0052] In the formula, r0 is the geometric mean radius, σ0 is the geometric standard deviation, n(r) is the size distribution function, and r is the droplet radius. From the above formula, it can be seen that the size distribution of water mist is related to the geometric mean radius and the geometric standard deviation. Therefore, the change of water mist volume percentage with radius when the geometric mean radius is 2.0 microns, 2.5 microns and 3.0 microns, and the change of water mist volume percentage with radius when the geometric standard deviation is 0.3, 0.5 and 0.7 are calculated respectively. Figure 3 It can be seen that as the geometric mean radius increases, the peak value of the particle size distribution shifts to the right, and the smaller the geometric standard deviation, the more concentrated the particle size distribution.

[0053] Then, the efficiency factor of the droplets at different radii is obtained according to the Mie theory, and the extinction, scattering and absorption coefficients are obtained by weighted summation of the size distribution function, and the influence of the geometric mean radius, geometric standard deviation and water mist volume fraction on the extinction coefficient is studied. Figure 4 It can be seen that the extinction coefficient of the fog environment has an obvious bimodal distribution. The geometric mean radius and geometric standard deviation of the water mist have little effect on the extinction coefficient. The volume fraction of the water mist f v The influence on the extinction coefficient is significant. Based on this, the water mist transmittance is calculated as a function of the geometric mean radius, geometric standard deviation, water mist volume fraction and detection distance, as shown in Figure 2. Figure 5 As shown, it can be seen that the wavebands with higher water mist transmittance are all between 10 and 12 microns, with 11 microns being the best.

[0054] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting high temperature source points in a closed space smoke environment, characterized in that: The steps include: Acquire an infrared radiation image of the monitoring area of ​​the enclosed space, and determine the location of the high temperature source point in the enclosed space based on the infrared radiation image; Among them, for closed spaces where steam leakage occurs, infrared radiation images in the 10μm to 12μm infrared band are obtained; for closed spaces where fire occurs, infrared radiation images in the 80μm and above infrared bands are obtained.

2. The high temperature source detection method in a closed space smoke environment as claimed in claim 1, characterized in that: For enclosed spaces where steam leaks occur, infrared radiation images in the 11μm infrared band are acquired.

3. The high temperature source detection method in a closed space smoke environment as claimed in claim 1, characterized in that: For enclosed spaces where fire occurs, infrared radiation images in the 80μm infrared band are obtained.

4. The high temperature source detection method in a closed space smoke environment as claimed in claim 1, characterized in that: At least one pair of camera units is set in the closed space to obtain infrared radiation images of the monitoring area of ​​the closed space; the detection directions of the two camera units in each pair of camera units are perpendicular to each other, and it is ensured that the monitoring area is within the viewing angle of the camera unit.

5. The high temperature source detection method in a closed space smoke environment as claimed in claim 4, characterized in that: A spectroscope is arranged in front of the lens of the camera unit to adjust the infrared detection band.

6. The high temperature source detection method in a closed space smoke environment as claimed in claim 4, characterized in that: According to the infrared radiation images obtained by a pair of camera units, the corresponding directional radiation intensity is calculated respectively, so as to determine the specific location of the high temperature source point in the closed space.

7. The high temperature source detection method in a closed space smoke environment as claimed in claim 6, characterized in that: The inverse Monte Carlo method is used to analyze the infrared radiation image and obtain the corresponding directional radiation intensity.

8. A detection system for implementing the high temperature source detection method in a closed space smoke environment as described in any one of claims 1 to 7, characterized in that: It includes a camera unit and an information unit, wherein: The camera unit is arranged in the closed space and is used to collect the video of the monitoring area in real time and obtain the infrared radiation image of the monitoring area when a fire or steam leakage occurs; The information unit is arranged outside the closed space and is connected to the imaging unit, and is used to determine the location of the high temperature source point according to the infrared radiation image acquired by the imaging unit.

9. The detection system according to claim 8, characterized in that It also includes a monitoring station for displaying the video and infrared radiation images acquired by the camera unit in real time and issuing an audible and visual alarm in the event of a fire or steam leakage.

10. The detection system according to claim 9, characterized in that It also includes a storage unit for storing the video acquired by the camera unit. The video stored in the storage unit can be retrieved by the monitoring station at a later time.

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