JP2008199173A - Pilot flame monitoring method and its apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pilot flame monitoring method and its apparatus for surely monitoring pilot flame by photographing the pilot flame at the tip of a chimney by a monitoring camera from a remote position and image-processing the picked-up image. <P>SOLUTION: The pilot flame monitoring method is for monitoring the pilot flame 9 when burning an inflammable gas discharged from the chimney 8 provided with a pilot burner by the pilot burner. The tip of the chimney 8 is photographed by the monitoring camera 10 through a filter 11 for interrupting the wavelength of a visible light region, the processing area of the picked-up image of the tip of the chimney photographed by the monitoring camera 10 is image-processed to extract the image of the pilot flame 9, and the burning state at the tip of the chimney is judged from the flame part image area of the image of the pilot flame 9. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, a flammable gas emitted in a refining process of an oil plant or the like is ignited and burned by a pilot burner provided in a chimney and discharged to the outside, and a pilot flame monitoring for monitoring a chimney tip flame (pilot flame) The present invention relates to a method and an apparatus thereof.

  Conventionally, in an oil refinery plant, unnecessary flammable gas separated and discharged in the refining process is ignited and burned by a pilot burner installed at the chimney tip, and the pilot flame, which is the chimney tip flame, is released. If it disappears, the combustible gas will be scattered outside without being burned, causing problems such as air pollution, environmental pollution, or environmental destruction, and monitoring whether the pilot flame is normal or not. Is prevented from being discharged outdoors.

  There is a method of monitoring the temperature of the burner part with the temperature sensor installed in the pilot burner to monitor the pilot flame at the chimney tip, but if the temperature sensor or its cable is damaged, it is determined that the temperature sensor is broken, Even if the pilot flame disappears, it will not react, and flammable gas will be sprinkled, and if you detect an abnormality and try to replace the temperature sensor etc. installed at the chimney tip, it will be high and toxic gas will be emitted from the chimney tip In this state, the temperature sensor or the like cannot be easily replaced, and such a temperature sensor or the like cannot be replaced during the maintenance period. In addition, there is a method in which the pilot flame is photographed and monitored with a monitoring camera. However, depending on the weather conditions, the pilot flame may not be confirmed, and there is a possibility that the pilot flame is misunderstood.

  Since a method of monitoring the pilot flame at the tip of the chimney with a monitoring camera is not well known, an example in which image processing is used when detecting a flame or gas smoke in a fire will be described as a conventional example. FIG. 10 is a block diagram showing a flame / gas smoke detection system. The flame / gas smoke detection system 1 includes a photographing means 2 for photographing a landscape S, and an image signal from the photographing means 2 is converted to a landscape change detecting means 3. The result is input to the reference captured image analysis unit 4 and analyzed, and the analysis result is stored in the reference captured image analysis result storage unit 5. The reference photographed image analysis means 4 analyzes a normal image in which no flame or gas smoke of the scenery S is generated and uses it as a reference photographed image. On the other hand, the scene change detection means 3 divides the detection photographic image into blocks, detects the scene change of the detection photographic image by difference processing or the like, and inputs it to the landscape change block analysis means 6, A comparative analysis is performed and input to the flame / gas smoke determination means 7 to determine flame or gas smoke (for example, see Patent Document 1).

  In addition, some conventional flame detection devices detect flames from changes in the area of light and dark areas by image processing (see, for example, Patent Document 2).

Japanese Patent Laying-Open No. 2006-268200 (Description [0022] to [0039], Drawing 1) Japanese Patent Laid-Open No. 2001-14571 (FIGS. 1 and 4)

  Unnecessary combustible gas separated and discharged in the refining process in an oil refinery plant, etc. is sent to the chimney, burned by the pilot burner provided at the chimney tip, and discharged to the outdoors. When the pilot flame disappears, the combustible gas Will be scattered outside without burning, which may cause environmental destruction and the like, and pilot flames are monitored to avoid such problems. For example, a method of monitoring the temperature of the burner part of the pilot burner installed at the chimney tip with a temperature sensor is adopted, but if the temperature sensor breaks down, toxic gas is easily released in an unburned state, and even at high places There was maintenance and management, and there was room for improvement. Therefore, there is a search for a method to monitor the pilot flame at the tip of the chimney by installing a monitoring camera at a remote location, but the images taken with the monitoring camera are misidentified that are difficult to monitor due to weather conditions, sunlight conditions, etc. There was a problem that it was easy to do, and there was room for improvement.

  The present invention has been made in view of the above problems, and by taking a pilot flame at the tip of a chimney with a surveillance camera from a remote position and processing the captured image, the pilot flame can be reliably monitored. An object of the present invention is to provide a pilot flame monitoring method and apparatus therefor.

The present invention achieves the above-mentioned problems, and the invention according to claim 1 is a pilot flame monitoring method for monitoring a pilot flame when combustible gas discharged from a chimney is burned by a pilot burner.
The chimney tip is photographed by a monitoring camera equipped with a filter that absorbs a wavelength in the visible light region, and a captured image of the chimney tip photographed by the monitoring camera is subjected to image processing to obtain a binarized processed image of the pilot flame. The pilot flame monitoring method is characterized in that the combustion state of the chimney tip is determined from the flame image area of the binarized image.

  The invention according to claim 2 is the pilot flame monitoring method according to claim 1, wherein the filter transmits near-infrared light of 0.7 to 2.5 μm which is a wavelength in an infrared region. The invention according to claim 3 is the pilot flame monitoring method according to claim 1 or 2, wherein the combustion state of the chimney tip is determined by comparing the flame image area with a predetermined threshold. According to a fourth aspect of the present invention, when the combustion state of the chimney tip is determined and it is determined that the pilot flame has disappeared, an alarm is issued and the pilot burner is re-ignited. Item 4. The pilot flame monitoring method according to Item 1, 2, or 3.

Further, the invention of claim 5 is a pilot flame monitoring device for monitoring a pilot flame when combustible gas discharged from a chimney is burned by a pilot burner.
Imaging means for imaging the chimney tip through a filter that absorbs wavelengths in the visible light region;
A density processing means for binarizing the captured image of the chimney tip imaged by the imaging means;
Flame part extracting means for extracting a flame part image of the pilot flame image from the binarized processed image by the density processing means;
Flame part image area calculating means for calculating a flame part image area of the flame part image by the flame part extracting means;
A pilot flame monitoring device comprising combustion state determining means for determining the combustion state of the chimney tip from the flame image area calculated by the flame image area calculating means.

  The invention according to claim 6 is the pilot flame monitoring device according to claim 5, wherein the filter transmits near infrared rays having a wavelength in the infrared region of 0.7 to 2.5 μm. The invention according to claim 7 is characterized in that the combustion state determination means determines the combustion state of the chimney tip by comparing the flame image area with a predetermined threshold. A pilot flame monitoring device. In the invention of claim 8, when the combustion state determination means determines the combustion state of the chimney tip and determines that the pilot flame has disappeared, it issues an alarm and reignites the pilot burner. The pilot flame monitoring device according to claim 5, 6 or 7.

  According to the first aspect of the present invention, in the pilot flame monitoring method for monitoring the pilot flame when the combustible gas discharged from the chimney is burned by the pilot burner, the monitoring camera is equipped with a filter that absorbs a wavelength in the visible light region. A chimney tip is photographed, and a captured image of the chimney tip photographed by the monitoring camera is subjected to image processing to obtain a binarized image of the pilot flame, and the chimney is obtained from a flame part image area of the binarized image. Because it is a pilot flame monitoring method characterized by determining the combustion state of the tip, even if the weather and sunshine conditions change, the pilot flame is reliably monitored even if the infrared region wavelength is transmitted and photographed There is an advantage that can be. In addition, the surveillance camera can be installed at a location away from the chimney, and even if the surveillance camera breaks down, it can be easily replaced and the image processing function can be easily restored. Further, there is an advantage that it is not necessary for the monitor to constantly monitor the image of the monitoring camera, and it is easy to notify the abnormal combustion state.

  According to a second aspect of the present invention, there is provided the pilot flame monitoring method according to the first aspect, wherein the filter transmits near-infrared light having a wavelength in the infrared region of 0.7 to 2.5 μm. A pilot flame can be reliably photographed without being affected by conditions, sunshine conditions, and the like. The invention according to claim 3 is the pilot flame monitoring method according to claim 1 or 2, wherein the combustion state of the chimney tip is determined by comparing the flame image area with a predetermined threshold. It is possible to issue an alarm based on the determination result, and there is an advantage that monitoring is easy. The threshold value of the flame image area is arbitrarily determined depending on the installation conditions (size of pilot flame, weather condition, sunshine condition, etc.). According to a fourth aspect of the present invention, when the combustion state of the chimney tip is determined and it is determined that the pilot flame has disappeared, an alarm is issued and the pilot burner is re-ignited. Since it is the pilot flame monitoring method according to Item 1, 2, or 3, when the pilot flame disappears, the pilot burner can be immediately re-ignited, and harmful combustible gas is scattered as much as possible outdoors. There is an advantage that can be suppressed.

In the invention of claim 5, in the pilot flame monitoring device for monitoring the pilot flame when the combustible gas discharged from the chimney is burned by the pilot burner,
Imaging means for imaging the chimney tip through a filter that absorbs wavelengths in the visible light region;
A density processing means for binarizing the captured image of the chimney tip imaged by the imaging means;
Flame part extracting means for extracting a flame part image of the pilot flame image from the binarized processed image by the density processing means;
Flame part image area calculating means for calculating a flame part image area of the flame part image by the flame part extracting means;
Since it is a pilot flame monitoring device comprising combustion state determination means for determining the combustion state of the chimney tip from the flame image area calculated by the flame image area calculation means, The captured image can be automatically image-processed to determine the combustion state, and even if the weather condition or the sunshine condition changes, there is an advantage that the pilot flame can be reliably photographed and monitored unattended. In addition, the surveillance camera can be installed at a location away from the chimney, and even if the surveillance camera breaks down, it can be easily replaced and the image processing function can be easily restored. In addition, there is an advantage that the monitor does not need to constantly monitor the image of the monitoring camera.

  Further, in the invention of claim 6, since the filter transmits the near infrared ray of 0.7 to 2.5 μm that is the wavelength of the infrared region, the pilot flame monitoring device according to claim 5, Pilot flames can be reliably photographed without being affected by weather conditions, sunlight conditions, and the like. The invention according to claim 7 is characterized in that the combustion state determining means determines the combustion state of the chimney tip by comparing the flame image area with a predetermined threshold value. Since it is a pilot flame monitoring device, it is possible to issue an alarm based on the determination result, and there is an advantage that monitoring is easy. The threshold value of the flame image area is arbitrarily determined depending on the installation conditions (size of pilot flame, weather condition, sunshine condition, etc.). Further, in the invention of claim 8, when the combustion state determination means determines the combustion state of the chimney tip and determines that the pilot flame has disappeared, it issues an alarm and reignites the pilot burner. The pilot flame monitoring device according to claim 5, 6 or 7, wherein when the pilot flame disappears, the pilot burner can be immediately re-ignited and harmful combustible gas is discharged outdoors. There is an advantage that it can be suppressed as much as possible.

  Hereinafter, an embodiment of a pilot flame monitoring method and apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a pilot flame monitoring apparatus according to the present invention, and FIG. 2 is a diagram showing a control flow for determining the combustion state of this embodiment. FIG. 3 shows a chimney for discharging the combustible gas separated and discharged in the refining process in an oil refinery plant or the like, and is an image in which the combustible gas is burned. FIG. 4A is a diagram showing the wavelengths of visible light and flame, and FIG. 4B is a diagram showing the characteristics of the filter used in this embodiment. FIG. 5 is a diagram showing the filter characteristics of the filter used in the example. 6 (a), 6 (b) to 9 (a), 9 (b) are diagrams showing captured images showing a combustion state by the pilot flame of the chimney tip shown in FIG. 3 (a). FIG. 6 is a diagram illustrating a processed image obtained by performing image processing on the captured image of (a).

  An embodiment of the present invention will be described with reference to FIG. First, in FIG. 1, reference numeral 8 denotes a chimney for discharging a combustible gas separated and discharged in a refining process in an oil refinery plant or the like. This kind of chimney has a combustible gas at the tip of the chimney as shown in FIG. It is burning. A pilot burner is installed at the tip of the chimney 8 to ignite the pilot burner and burn a combustible gas by a seed fire. Reference numeral 9 denotes a chimney tip flame (pilot flame). A surveillance camera (imaging means) 10 is installed on the roof of another building away from the chimney 8, and a filter 11 is attached to the lens 12, and a pilot flame 9 of the chimney 8 to be monitored is photographed and monitored (not shown). To display. The filter 11 is a visible light absorption / infrared transmission filter.

  As shown in FIG. 4 (a), the wavelength of the pilot flame 9 to be monitored has the maximum relative intensity of wavelengths of about 400 to 700 nm in the visible light region of sunlight. In other words, the wavelength in the infrared region is abruptly attenuated, whereas the wavelength in the infrared region is stronger in relative intensity than the wavelength in the visible light region. Therefore, the filter 11 has a filter characteristic that absorbs visible light and transmits infrared light, as shown in FIG. Even if the filter 11 absorbs the wavelength of the visible light region of the flame, most of the wavelength region is the infrared region, and since the infrared light passes through the filter 11, the influence of the background and sunlight is eliminated, and the flame portion to be monitored is imaged. It can be detected as an image.

  The image processing apparatus 20 is provided with a processor dedicated to image processing. An image pickup signal from the monitoring camera (image pickup means) 10 is input, the picked-up image is processed by the processor dedicated to image processing, and a control signal (alarm output signal / reignition) Control signal). The image processing apparatus 20 reads an image signal from an image input means (frame memory) 21 that receives an imaging signal and stores it as a still image, and an image signal from the image input means (binarization processing unit) 21, and performs binarization processing. An image processing unit 22 for calculating an area of a monitoring target image (flame portion or the like) by defining an area and a combustion state determination unit 23 are provided. The image processing unit 22 includes a density processing unit 22a for binarizing the image signal, a flame part extracting unit 22b for extracting a flame part by determining a processing area from the binarized image, and the number or area of pixels of the flame part. Flame partial area calculating means 22c for calculating from the above is provided. The calculation result (flame area value) of the flame partial area calculation unit 22c is input to the combustion state determination unit 23, and is compared with a predetermined threshold value. Based on the determination unit, the combustion state (combustion or extinction) is determined. A control signal is output after the determination.

  Next, the processing flow of the combustion state determination in this embodiment will be described with reference to FIG. This processing flow includes steps S1 to S7. First, in step S1, a captured image of the monitoring camera (imaging means) 10 is captured as a still image in the image input means (frame memory) 21, and the process proceeds to step S2. In step S2, the brightness processing means 22a binarizes the brightness level of the still image with a predetermined threshold value, and binarized image data (pixel data based on “0” and “1”: for example, “1” is an image of a flame. Area) and the process proceeds to step S3. In step S3, the flame portion is extracted from the pixel data “1” of the binarized image data of the processing area including the pilot flame portion (hereinafter referred to as the flame portion) by the flame portion extraction means 22b, and the process proceeds to step S4.

  In step S4, the number of pixels or area of the flame part of the pixel data “1” corresponding to the pilot flame 9 is calculated by the flame part area integrating means 22c, and the process proceeds to step S5. In step S5, if the combustion state determining means 23 compares the number of pixels or area of the flame portion with the set threshold value, and if it is determined that the flame portion area exceeds the predetermined threshold value, normal combustion is performed. Return to S1. If it is determined that there is a possibility that the flame partial area is less than or equal to the predetermined threshold value, the process proceeds to step S6. In addition, step S6 is processed by the combustion state determination means 23 similarly to step S5, and a control signal is output as the processing result.

  In step S6, when a predetermined number of times of processing for determining that the pilot flame has completely disappeared (the number of times of flame disappearance) is set, and the number of times the processing in steps S1 to S5 is repeated satisfies the condition “number of times of processing ≧ set value” Then, it is determined that the pilot flame has completely disappeared, and the process proceeds to step S7. In step S6, the total disappearance is determined from the disappearance time in consideration of the time when the predetermined number of processes is equal to or less than the predetermined numerical value and it is determined that the flame disappears. Total disappearance can be determined from one processing time × number of processing times ≧ time (about several seconds) determined to be total disappearance of flame. That is, step S6 determines a process in which the flame is gradually extinguished while the pilot flame disappears or arrives and the flame disappears completely. In step S7, when the condition of step S6 is satisfied, a control signal is output, an alarm is output, or the pilot burner is re-ignited. Note that the pilot burner is re-ignited automatically, but may be manually performed by a supervisor based on an alarm.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1, 2, 5 and 6 to 9. The pilot flame monitoring apparatus of the present embodiment includes a processor dedicated to image processing, and the configuration thereof is as shown in the block diagram of FIG. 1. The monitoring camera 10 is a CCD camera, and the filter 11 attached to the lens 12 is A filter having a filter characteristic shown in FIG. 5 was used. The surveillance camera 10 was installed at a position where the pilot flame at the edge of the chimney can be photographed. The determination of the combustion state of the pilot flame was performed by the image processing device 20 in the processing flow of FIG. The image captured by the monitoring camera 10 is stored in the image input means (frame memory) 21 as a still image that is a monitoring target image. The still image is read from the image input means 21 and converted into a binarized image by the density processing means 22a. After conversion, the combustion state of the pilot flame was determined. The flame part extracting unit 22b extracts the flame part of the binarized image from the processing area, and the flame part area calculating unit 22c calculates the number of pixels of the flame part. In the combustion state determination means 23, the determination process of the number of pixels of the flame portion is performed. When the area of the flame portion is less than 10% of the area of the determination region, it is determined that the pilot flame has disappeared, and this disappearance state remains for several seconds. For example, in the case of continuing for 1 to 3 seconds, it is determined that the pilot flame has completely disappeared and a control signal (re-ignition control signal, alarm signal) is output. The area ratio and the duration of the flame extinguishing state depend on the oil refining plant and may be set experimentally.

  Next, referring to FIGS. 6A and 6B to FIGS. 9A and 9B for still images and binarized images obtained by imaging the pilot flame 9 according to this embodiment and performing image processing. To explain. FIG. 6A shows the output of the image input means 21 and is an image obtained by photographing the pilot flame 9 at the tip of the chimney 8 at dusk. FIG. 6B shows the image binarized by the grayscale processing means 22a. The binarized image obtained in this way is shown. The surveillance camera (imaging means) 10 images the pilot flame 9 in the near-infrared region, recognizes that the bright portion of the pilot flame 9 is a flame, sets the flame portion to “1”, and is a region other than the flame portion. Is set to “0”, binary image data based on pixel data “0” and “1” is obtained. In FIG. 6B, the white portion is an image of “1” pixels, the portion of “0” pixels is shown in black, and a flame processing area calculation unit 22c sets a reference processing area. In FIG. 7B to FIG. 9B, the processing area is set and the area of the flame portion is calculated.

  FIG. 7 is an example of shooting the pilot flame 9 at night, FIG. 7A is an image of the pilot flame 9, and FIG. 7B shows the flame portion with a pixel “1”. This is binarized image data whose part is indicated by a pixel of “0”. FIG. 8 is an example in which a pilot flame 9 with a large flame is photographed during sunny daytime, FIG. 8 (a) is a still image obtained by photographing the pilot flame 9, and FIG. ”And binarized image data in which the other portions are indicated by“ 0 ”pixels. FIG. 9 is an example in which the pilot flame 9 with a small flame is photographed in sunny daytime, FIG. 9A is a still image obtained by photographing the pilot flame 9, and FIG. This is binarized image data indicated by pixels and the other parts indicated by “0” pixels.

  In particular, when the flame of the pilot flame 9 is small during daylight weather, it may be mistaken for having disappeared. However, as shown in FIG. If the area of the flame part is 10% or more of the area of the judgment area in the area ratio between the data and the image data of “0” other than the flame part, it is detected that the pilot flame 9 has not disappeared. If the area of the flame portion is less than 10% of the area of the determination region, the possibility of disappearance can be detected. If this state is detected continuously for a predetermined time, the pilot flame 9 is completely exhausted. It was demonstrated to detect disappearance. In addition, the ratio of the area used for determining whether the pilot flame 9 has not disappeared or has completely disappeared can be freely set depending on the monitoring target.

  As an application example of the present invention, combustible gas generated in a refinery process of a petroleum plant can be combusted and prevented from being discharged outdoors, and can be used as a device for preventing environmental destruction. It is possible to avoid the occurrence of an explosion accident by staying in the plant.

It is a block diagram showing one embodiment of a pilot flame monitoring device concerning the present invention. It is a figure which shows the control flow which determines the combustion state of this embodiment. It is the image which shows the chimney which discharges | emits the combustible gas isolate | separated and discharged | emitted by the refinement | purification process in an oil refinery plant etc., and combustible gas is burning. (A) is a figure which shows the wavelength of visible light and a flame, (b) is a figure which shows the characteristic of the filter used for this embodiment. It is a figure which shows the filter characteristic of the filter used in the present Example. (A) is a figure which shows the captured image which shows the combustion state by the pilot flame at dusk, (b) is a figure which shows the binarized image which image-processed the captured image. (A) is a figure which shows the captured image which shows the combustion state by the pilot flame at night, (b) is a figure which shows the binarized image which image-processed the captured image. (A) is a figure which shows the picked-up image which shows the combustion state by the pilot flame with a large flame at the time of daytime fine weather, (b) is a figure which shows the binarized image which image-processed the picked-up image. (A) is a figure which shows the captured image which shows the combustion state by the small pilot flame in the daytime fine weather, (b) is a figure which shows the binarized image which image-processed the captured image. It is a block diagram which shows the conventional flame and gas smoke detection system.

Explanation of symbols

8 Chimney 9 Chimney tip flame (pilot flame)
10 Surveillance camera (imaging means)
DESCRIPTION OF SYMBOLS 11 Filter 12 Lens 20 Image processing apparatus 21 Image input means (frame memory)
22 Image processing unit 22a Density processing unit (binarization processing unit)
22b Flame part extraction means 22c Flame part area calculation means 23 Combustion state determination means

Claims (8)

In the pilot flame monitoring method for monitoring the pilot flame when the combustible gas discharged from the chimney is burned by the pilot burner,
The chimney tip is photographed by a monitoring camera equipped with a filter that absorbs a wavelength in the visible light region, and a captured image of the chimney tip photographed by the monitoring camera is subjected to image processing to obtain a binarized processed image of the pilot flame. A pilot flame monitoring method comprising: determining a combustion state of the chimney tip from a flame image area of the binarized image.   2. The pilot flame monitoring method according to claim 1, wherein the filter transmits near-infrared light having a wavelength in the infrared region of 0.7 to 2.5 μm.   The pilot flame monitoring method according to claim 1 or 2, wherein the combustion state of the chimney tip is determined by comparing the flame area image area with a predetermined threshold.   The combustion state of the chimney tip is determined, and when it is determined that the pilot flame has disappeared, an alarm is issued and the pilot burner is re-ignited. Pilot flame monitoring method. In the pilot flame monitoring device for monitoring the pilot flame when the combustible gas discharged from the chimney is burned by the pilot burner,
Imaging means for imaging the chimney tip through a filter that absorbs wavelengths in the visible light region;
A density processing means for binarizing the captured image of the chimney tip imaged by the imaging means;
Flame part extracting means for extracting a flame part image of the pilot flame image from the binarized processed image by the density processing means;
Flame part image area calculating means for calculating a flame part image area of the flame part image by the flame part extracting means;
A pilot flame monitoring device comprising combustion state determining means for determining a combustion state of the chimney tip from a flame image area calculated by the flame image area calculating means.   6. The pilot flame monitoring apparatus according to claim 5, wherein the filter transmits near-infrared rays having a wavelength in the infrared region of 0.7 to 2.5 [mu] m.   The pilot flame monitoring device according to claim 5 or 6, wherein the combustion state determination means determines the combustion state of the chimney tip by comparing the flame image area with a predetermined threshold value.   6. The combustion state determining means determines a combustion state of the chimney tip, and when determining that the pilot flame has disappeared, issues a warning and reignites the pilot burner. The pilot flame monitoring device according to 6 or 7.