RU2152065C1 - Method for checking of inner surface of chimney and device for its embodiment - Google Patents

Abstract

FIELD: heat production equipment. SUBSTANCE: method involves illumination of inner chimney surface, observing illuminated piece on chimney perimeter and judging chimney quality by produced image. Illumination is achieved by means of laser beam, which is shaped as ring on chimney surface. Image of illuminated piece is converted into perpendicular plane. Surface state is judged by degree and shape of distortion of produced ring image in perpendicular plane. Respective device has light source, optical system and light receiver. Light source is designed as laser, which has conic reflector of electromagnetic radiation. Optical system provides possibility of projecting ring chimney perimeter into its perpendicular plane. Receiver is located in chimney section. EFFECT: increased functional capabilities, increased precision of checking. 5 cl, 5 dwg

Description

 The invention relates to measuring equipment and can be used in the power system to monitor the condition of the internal surfaces of chimneys without stopping the boilers.

 A known method of controlling the inner surface of the chimney and a device for its implementation, including illuminating the inner surface of the chimney with a light source, sighting the highlighted area with a camera, judging the state of the surface from the obtained image [1].

 In this technical solution, the backlighting is carried out from an autonomous light source, and an automatic camera is used as a camera.

 The disadvantages of the technical solution are: the need to stop the boilers for the period of assessing the condition of the inner surface of the pipe, the long duration of the control, the obtained photographs do not contain information about the depth of defects of the controlled surface, since surfaces with deposited soot can be taken for defects, which generally reduces reliability and accuracy control.

 The closest technical solution for the claimed method is a method of controlling the inner surface of the chimney, including highlighting the inner surface of the chimney, sighting the highlighted area on the inner surface of the chimney, judging the state of the surface according to the image [2].

 The closest technical solution for the claimed device is a device for monitoring the inner surface of the chimney containing a backlight, a video system made of at least one camera with the ability to view the image of the inner surface of the pipe [2].

 In the known method and device, the backlighting is carried out by a light source, and the video system contains five cameras capable of simultaneously vising the image of the inner surface of the pipe. While moving the backlight and cameras along the longitudinal axis of the pipe, an analysis of the controlled surface is performed without stopping the boilers. For example, if damage is noticed, the operator can stop the descent of the device, select the most conveniently oriented camera from the five available and focus the image on the damage in order to examine it in more detail. Thus, in comparison with the previous technical solution, it is possible to increase the efficiency of monitoring the state of the pipe surface.

 However, the analysis of the surface condition using five cameras and the further focusing of one of them reduces the speed of monitoring the entire inner surface. The electromagnetic light radiation of the source is in no way connected with the resulting image and serves only to illuminate the surface. The main limitation is the low reliability of the control, since it is impossible to measure the depth of the defect, at the same time, dark spots on the surface of the pipe, caused, for example, by soot deposits, can be perceived as defects. The presence of five cameras complicates the design of the device, since each of the cameras is independent with its own lens, and it is necessary to monitor information which of the cameras is aimed at the defect.

 The problem solved by the invention is the expansion of functionality and improving the quality of control.

 The technical result that can be obtained by implementing the claimed method is to increase the accuracy, reliability and speed of control.

 The technical result that can be obtained by performing the claimed device is to increase the accuracy of control and simplify the design.

To solve the problem in the known method of controlling the inner surface of the chimney, including highlighting the inner surface of the chimney, sighting the highlighted area on the inner surface of the chimney, judging the surface condition according to the image, according to the invention, the illumination is formed by laser radiation in the form of a ring on the inner surface of the chimney, transform the image of the highlighted area in the transverse plane of the pipe, and a judgment on the state of the surface is made by the degree and shape of the claim the resultant ring image in the said transverse plane in accordance with the mathematical expression,
ΔZ = ΔY / (tgα-tgβ),
where ΔZ is the true value of the depth of the defect,
ΔY is the measured value of the curvature of the annular image in the transverse plane,
α is the angle of incidence of the laser beam on the pipe surface, defined as the angle between the axis of the probe laser beam and the normal to the controlled surface of the pipe,
β is the angle of sight, defined as the angle between the direction of sight to the controlled surface of the pipe and the normal to this surface.

 An additional embodiment of the method is possible, in which it is advisable that the backlight is moved along the longitudinal axis of the pipe while moving the transformable image.

 To solve the problem in the known device for monitoring the inner surface of the chimney containing a backlight, an optical system in the form of a lens, configured to visually image the inner surface of the pipe, according to the invention, a laser equipped with a conical reflector of electromagnetic radiation in front of the lens is selected as a backlight a mirror lens and a curvature compensator installed along the longitudinal axis of the pipe with the possibility of projecting rings Vågå images pipe inner surface in its transverse plane, the lens is mounted receiver, and between the illumination source and the conical reflector lens mounted.

Additional embodiments of the device are possible, in which it is advisable that:
- the illumination source was made of semiconductor lasers, and the conical reflector was made in the form of elements of a reflector system, each of the semiconductor lasers would be located at the same distance from the longitudinal axis of the tube in one transverse plane with the possibility of directing the laser beam to one of the elements of the reflector system by means of lenses for forming a laser beam mounted between semiconductor lasers and corresponding elements of the reflector system;
- an electronic processing unit was introduced, the input of which is connected to the output of the receiver and which would be designed to record the signal of the receiver or to transmit it via wired or wireless communication lines to a video monitor located outside the pipe, or to convert the signal to digital form for estimating depth defect.

 These advantages, as well as features of the present invention are illustrated by the best option for its implementation with reference to the accompanying drawings.

FIG. 1 schematically depicts a device for monitoring the inner surface of a chimney;
FIG. 2 is a projected image in the transverse plane of the pipe in case of a crack in the lining of the pipe;
FIG. 3 is the same as FIG. 2, in the case of a protrusion in the lining of the pipe formed by deposits on its surface;
FIG. 4 is a diagram explaining the relationship of the true value of the depth of the defect with the measured amount of curvature of the annular image in the transverse plane of the pipe;
FIG. 5 is an embodiment of a radiation source from semiconductor lasers with elements of a reflector system (schematically, in longitudinal section).

 Since the claimed method is implemented when the device is used to control the inner surface of the chimney, its description is given in the description of the operation of the device.

 A device for monitoring the inner surface of the chimney (Fig. 1) contains a light source 1, an optical system 6 in the form of a lens 9, configured to sight the image of the inner surface of the pipe 3 to the receiver 4.

 Source 1 is made of a laser and is equipped with a conical reflector 5 of electromagnetic radiation. A source 1 and a conical reflector 5 are installed along the longitudinal axis of the pipe 3. Into the optical system 6, configured to project an image of the annular perimeter of the pipe 3, in addition to the lens 9, a mirror lens 7, a curvature compensator 8 are introduced, and a receiver 4 is mounted on the longitudinal axis pipes in said transverse plane.

 This embodiment of the device further simplifies its design, since with the known internal diameter of the pipe 3 and the geometric dimensions of the remaining elements, it is easy to focus the annular image of the pipe 3 in the transverse plane and it is not necessary, as in the closest analogue, to focus individually on each camera. In the claimed device, the camera may have a simple design with a single lens 9.

 To further increase the accuracy of measurements, a lens 10 can be introduced to form a parallel laser beam from the source 1, mounted on the longitudinal axis of the tube 3 between the laser and the conical reflector 5. Lens 10 allows you to form a sufficiently narrow beam to accurately determine the location of the defect along the longitudinal axis of the tube 3 .

 An electronic processing unit 11 may also be introduced, the input of which is connected to the output of the receiver 4. Depending on the scope and functionality of the device as a whole, the electronic unit 11 may, for example, record the video signal of the receiver 4 by electronic or magnetic means for further analysis. Or, the electronic unit 11 can be used to transmit a signal via wired or wireless communication lines to a video monitor (not shown in Fig. 1) located outside the pipe 3. In addition, the electronic unit 11, in the case of its other functional design, can serve as a video to digital converter form for subsequent evaluation by the processor of the depth of the detected defect. However, the defect itself in the claimed device can be estimated by the amount of distortion of the received image in the transverse plane (Fig. 2-4). Therefore, the functionality of the device as a whole is expanded, and the electronic unit 11 can be made using various technical means, and for simple visual control of the inner surface of the pipe 3, a video monitor can be used, as in the closest analogue, however, on the monitor screen when using the claimed device not an alternation of spots will be observed, for example, from soot deposits, but directly an annular image with a corresponding depth of convexity or depression (Fig. 2, 3).

 To ensure the ability to control both the entire annular image and its individual sections, as well as to reduce the dimensions of the device, the backlight source 1 (Fig. 5) can be made of semiconductor lasers 12, and the conical reflector 5 can be made in the form of elements 13 of the reflector system . Each of the semiconductor lasers 12 in this case is located at the same distance from the longitudinal axis of the tube 3 in one transverse plane with the possibility of directing the laser beam to one of the elements 13 of the reflector system through lenses 14 to form a laser beam. The lenses 14 in this case are installed between the semiconductor lasers 12 and the corresponding elements 13 of the reflector system. The external surface directed to the tube 3, the surface of the elements 13 of the reflector system for this option forms a single conical reflector 5. When powering the semiconductor lasers 12, together or separately, it is possible to illuminate the inner surface of the tube 3 along the entire annular profile or its individual sections. In addition, since the position of the semiconductor lasers 12 does not change when the device is moved along the longitudinal axis of the tube, when connecting individual semiconductor lasers, it is easy to determine the location of the defect in the inner surface of the tube.

 The device operates (Fig. 1) as follows.

 The backlight is formed in the form of a ring on the perimeter of the pipe by laser radiation from the source 1. For this, the laser beam passes through the lens 10 and is reflected by a conical reflector 5, for example, made mirror, along the perimeter of the inner surface of the pipe 3. Thus, in contrast to the known method, a light spot not indefinitely blurred, but create a light ring strip on a controlled surface.

 Then, the image of the highlighted area is transformed into a transverse plane. For this, the mirror lens 7 forms an image of an annular band distorted by defects of the surface to be monitored on the image surface (Fig. 2, 3). The compensator 8 of the curvature of the field of view in conjunction with the camera lens 9 projects an image onto the sensitive layer of the radiation receiver 4.

 The judgment on the state of the inner surface of the pipe 3 is made by the degree and shape of distortion of the obtained annular image in the transverse plane. Due to the fact that an annular strip from the laser is projected onto the controlled surface, it becomes possible to control and measure the depth of defects (Fig. 2,3).

 To control the entire inner surface of the pipe 3, the device together with the source 1 and the optical system 6 is moved along the longitudinal axis of the pipe 3 (Fig. 1).

 The judgment on the state of the surface (Fig. 4) is carried out in accordance with the above formula ΔZ = ΔY / (tgα-tgβ), which determines the depth of the defect of the cavity or bulge (Fig. 2, 3).

 The most successfully claimed method of controlling the inner surface of the chimney and a device for its implementation can be used in the power industry to monitor the condition of the inner surfaces of the chimneys without stopping the boilers. The manufacture of the device can be carried out using the existing element base at the enterprises of the optoelectronic industry.

Sources of information:
[1] . "Guidelines for the inspection and maintenance of brick and reinforced concrete pipes." SISIND International Committee for Industrial Chimneys, 1992, p. 194.

 [2]. “Introducing a new hot chamber for interactive viewing of chimneys from the inside”, G. Oudin, Report at the 48th SISD Conference, Germany, Cologne, 04/26/97.

Claims (5)

1. A method of monitoring the inner surface of the chimney, including highlighting the inner surface of the chimney, sighting the highlighted area on the inner surface of the chimney, judging the state of the surface according to the image, characterized in that the backlight is formed by laser radiation in the form of a ring on the inner surface of the chimney, transforming the image of the highlighted section in the transverse plane of the pipe, and a judgment on the state of the surface is made by the degree and shape of distortion of the obtained annular image said transverse plane in accordance with a mathematical expression
ΔZ = ΔY / (tgα-tgβ),
where ΔZ is the true value of the depth of the defect;
ΔY is the measured value of the curvature of the annular image in the transverse plane;
α is the angle of incidence of the laser beam on the pipe surface, defined as the angle between the axis of the laser beam and the normal to the controlled surface of the pipe;
β is the angle of sight, defined as the angle between the direction of sight to the controlled surface of the pipe and the normal to this surface.  2. The method according to claim 1, characterized in that the backlight is moved along the longitudinal axis of the pipe while moving the transformable image.  3. A device for monitoring the inner surface of the chimney containing a source of illumination, an optical system in the form of a lens, made with the possibility of sighting the image of the inner surface of the pipe, characterized in that the laser source equipped with a conical reflector of electromagnetic radiation is selected as a backlight, in front of the lens there is a mirror a lens and a curvature compensator mounted along the longitudinal axis of the pipe with the possibility of projecting an annular image of the inner surface t tubes in its transverse plane, a receiver is installed behind the lens, and a lens is installed between the backlight and the conical reflector.  4. The device according to claim 3, characterized in that the backlight is made of semiconductor lasers, and the conical reflector is made in the form of elements of a system of reflectors, each of the semiconductor lasers is located at the same distance from the longitudinal axis of the pipe in one transverse plane with the possibility of laser direction beam to one of the elements of the reflector system by means of lenses for forming a laser beam mounted between semiconductor lasers and the corresponding elements of the reflector system .  5. The device according to claim 4, characterized in that an electronic processing unit is introduced, the input of which is connected to the output of the receiver and which is designed to record the signal of the receiver or to transmit it via wired or wireless communication lines to a video monitor located outside the pipe, or for converting the signal to digital form to assess the depth of the defect.

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