Patent Grant
10161694
This application claims the priority benefit under 35 U.S.C. § 119 of French Patent Application No. 1662766, filed on Dec. 19, 2016, the content of which is hereby incorporated in its entirety by reference.
Some embodiments generally relate to the guiding of a high-pressure cleaning device, in view of cleaning the inside of heat exchanger tubes.
The high-pressure cleaning of the tubes of a heat exchanger is a periodic operation that it typically carried out as part of the maintenance of this type of installation. Currently, this is a mainly manual or semi-manual operation, an operator remotely operates, using a remote control, one or several rods assembled on a mobile gantry (called a bundle cleaner).
Yet, the high-pressure cleaning of the tubes of a heat exchanger is, according to operators who usually carry out this task, a task that is not only tiring (mainly because of the standing position of the operator and the impact of external conditions), but also tedious (repetitiveness, over a large number of tubes) and potentially harmful regarding the safety of the operator.
Indeed, to be able to visualize the result of the actions of positioning the bundle cleaner that they carry out, the operator positions themselves very close to the exchanger (in particular, at a distance of between 1 m and 5 m away), which exposes them to potentially contaminated water mist coming from the exchangers (contaminated with hydrocarbons).
Finally, operators handling via a rod (or triangle) or more generally, a bundle cleaner (not connected to the exchanger to be cleaned), with very high-pressure water jets, it can occur that the exchanger, during cleaning, moves because of the pressure of the jets, in particular, when a tube is clogged, even that the exchanger or bundle cleaner suddenly recoils (by a piston effect) or that the rod breaks. This adds an additional risk for the safety of the operator.
Moreover, it is probable that the tiredness connected to this type of task can also lead to potential errors and a progressive slowing-down of the task.
Moreover, the positioning of the cleaning devices is, currently, today carried out with the naked eye, which is only possible in times of cleaning, during which the operator remains capable of seeing the result of their actions of positioning the bundle cleaner, in other words, by positioning themselves at a distance from the exchanger of less than 5 m. This is not possible when there are a lot of projections, or when the weather conditions are not good, or when the operator is too far away (bad weather, in particular).
Thus, even if the cleaning operation is carried out on exchangers prepared beforehand, it is not optimal or beneficial that the positioning of the devices for cleaning heat exchanger tubes is only based on a visualization with the human eye. This makes detecting tube orifices and the relative position of the rails in relation to these orifices both too slow and too random, to achieve a robustness and an availability of the measurement in a broad spectrum of configurations.
To this end, the applicant has developed a method for guiding a high-pressure cleaning device, in view of cleaning the inside of the tubes of a heat exchanger, wherein the human eye has been replaced with an acquisition device, enabling to obtain images making it possible to automatically detect the tubes to be cleaned, with the possibility of remote visualization.
A related art device exists for cleaning heat exchanger tubes implementing a camera. Thus, U.S. Pat. No. 6,681,839 defines a cleaning device including a hose which is connected to a mechanism for positioning the hose equipped with a camera positioned on the heat exchanger. Such a device has the disadvantage of being connected to the exchanger, which may require resorting to flexible rails. In addition, such a device enables images to be acquired from the zone of positioning the rails only in the visible spectrum: this system is therefore very dependent on external conditions (in terms of lighting, projections, etc.).
In order to address or remedy this, the applicant has therefore developed a guiding method, wherein the camera and the lighting thereof are arranged independently of the exchanger, close to the cleaning device and not on the support plate of the exchanger, to align and correct the cleaning device with the exchanger tubes to be cleaned during a relative movement of one against the other.
More specifically, some embodiments are configured for guiding a high-pressure cleaning device, in view of cleaning the inside of the tubes of a heat exchanger with tube bundles that are substantially rectilinear, and which is not connected to the cleaning device (for example, U-shaped tubes), wherein:
By high-pressure cleaning device, this means, in the sense of the present embodiments, a device able to send liquid cleaning jets (in particular aqueous), at a high or very high pressure (pressure, in particular, between 200 Bars to 3000 Bars, and more specifically, around 1000-1400 Bars). Typically, this is a bundle cleaner, such as illustrated in
The orthogonal reference (x0, y0, z0) and comparison (x1, y1, z1) markers, respectively connected to the support plate and to the cart, are virtual markers, which could each be materialized by a target object able to emit or reflect light, easy to detect in space, for example, by a camera.
Thus, according to some embodiments, the following can advantageously be used:
To carry out the method according to some embodiments, the following steps can or must be carried out:
The first step of the method according to some embodiments is step A of taking a real image of the inlet or outlet orifices at the level of the support plate. For this, preferably or possibly a high-resolution camera is used, for example, a monochrome digital 16-Megapixel (4096×4096) camera.
Advantageously, a near-infrared camera equipped with an optical filter can be used, with light emitting in the near-infrared.
The camera must or should be remote in relation to the center of the support plate, so as to be able to photograph the whole of the support plate, so as to obtain a complete image of the support plate without being obstructed by the cleaning device. However, it must or should be ensured, that the center of the camera is not too far away from the center of the plate, to avoid any image processing problems. Finally, it can also be useful for many reasons (water projections, assembly on cleaning head difficult, etc.) to move the camera laterally, such that it is not in a parallel plane to that of the plate. In this case, it must or should be necessarily ensured that the angle formed by the optical axis of the camera and the axis that is orthogonal to the support plate enables the camera to film the whole of the plate. Preferably or possibly, this angle can be between 30° and 45°.
The second step of the method according to some embodiments is step B, of sending the real image to a first calculator, which identifies the shape and the position of the orifices (according to the marker (x0, y0, z0), as well as their possible obstruction. This sending can be done, for example, by wire or by radio waves.
Before a calculator proceeds with the calculation and with displaying the optimal or enhanced path (respectively steps F and G), it is important that the comparison marker (x1, y1, z1) connected to the cart is calibrated (step E) in relation to the reference marker (x0, y0, z0) connected to the support plate to enable the obtaining in real time of the position of the hose in relation to the orifices. The calibration phase consists of or includes coming to position the rods according to the four cardinal points in relation to the exchanger and to take a measurement at each position. By then entering the geometry of the different tubes, the system is self-calibrated and is capable of knowing the position that the comparison marker (x1, y1, z1) must or should have vis-à-vis the reference marker (x0, y0, z0). The geometry of the different tubes can come from information entered by the operator using simple tools, by using an image, for example, and/or the automatic detection of the tubes. It is therefore possible to project the current position of the rods onto the real or enhanced image.
From the real image, a calculator calculates (step D) an optimal or enhanced path for positioning the rod for cleaning the tubes, of which the orifices have the first visual marking, according to their arrangement in the marker (x0, y0 z0), the calibration between the reference (x0, y0 z0) and comparison (x1, y1 z1) markers and the number of cleaning rods that the cleaning device includes. This optimal or enhanced path defines an order of succession of the movements Dca of the rod along the axes x1 and y1 of the comparison marker, between which at least two movements Dch of the cart along the axis z1 (in other words, at least one two-way journey in relation to the departure point of the cart) take place to clean the tubes marked on the enhanced image.
This optimal or enhanced path, as well as the enhanced image with marked orifices, are displayed (step E) on a display screen.
During step F, the carrying out of a cleaning step Enet can be done by an operator (entirely manual mode) and/or by a robot controlled by an algorithm (automatic or semi-automatic mode) as follows:
Steps D to F are repeated (steps G) until all or most cleaning steps Enet provided by the optimal or enhanced path are carried out. These steps must or should not necessarily be carried out in the order provided by the optimal or enhanced path. If the cleaning step are not carried out in order, the second calculator recalculates the optimal or enhanced path at each step.
In the case of a manual cleaning method, it is possible to not follow the optimal or enhanced path. This is not possible if the cleaning is done by a robot controlled by an algorithm. These methods are explained below.
According to the manual embodiment, the operator controls all or most of the movements Dca and Dch of the rod during the cleaning step Enet, by following (or not) the order of succession of the movements Dca of the rod 11 defined by the optimal or enhanced path. In such an embodiment, all or most of the movements Dca of the rod provided by the optimal or enhanced path, are carried out by the operator, according to an order of succession which can be different to that which defines the optimal or enhanced path. In this case (order of succession different from the optimal or enhanced path), a calculator can actually indicate to the operator, the deviation in real time of the rod in relation to the optimal or enhanced path. Of course, the operator can choose to carry out all or most of the movements Dca of the rod according to the order of succession defined by the optimal or enhanced path.
In practice, in the manual mode, the operator positions the orthogonal comparison marker (x1, y1, z1) in relation to the orthogonal reference marker (x0, y0, z0), such that the hose (11) is arranged opposite an orifice to be cleaned that is chosen by the operator, by relying on the enhanced image and by considering (or not) the optimal or enhanced path proposed. A calculator (i.e. that which indicates to the operator the deviation in real time of the rod in relation to the optimal or enhanced path) continuously checks the alignment of the center of the orifice with the symmetry axis of the rod. While the alignment is not reached, this calculator sends back non-alignment information to the display screen, and the operator can continuously correct the positioning and the checking of the alignment.
According to the semi-automatic embodiment, the movements Dca of the rod along with axes x1 and y1 are carried out by a robot controlled by an algorithm, by following the order defined by the optimal or enhanced path, while an operator manually carries out the movements Dch of the rod along the axis z1. In such an embodiment, the robot controlled by an algorithm must or should wait for the operator to carry out the movements Dch before starting the movements Dca of the following cleaning step Enet+1.
To facilitate the manual positioning of the hoses opposite the orifices, it is possible to consider a digital zoom in the image stream coming from the camera.
For manual and semi-automatic embodiments, the operator needs the optimal or enhanced path displayed on the display screen.
In this case, it can be advantageous that the real image is enhanced. In this case, it can be advantageous that the real image is corrected, so as to give a recovered image before being sent to the first calculator to generate an enhanced image. This correction can, for example, be carried out by image processing and by using markers positioned on the support plate. Such a correction has an interest when the image is taken with a strong perspective effect by a camera that is laterally remote in relation to the center of the exchanger.
Once the recovered image is received by the first calculator, the latter, generates from the real image (step B′), possibly recovered beforehand, an enhanced image including a first visual marking of the orifices of the tubes to be cleaned (marked orifices). This enhanced image is then sent to a second calculator (step B″), which then calculates, during step D, the optimal or enhanced positioning path form the real image. This sending can be done, for example, by wire or by radio waves.
Advantageously, the enhanced image generated in step B′ can include, other than the first visual marking, a second visual marking showing tubes that do not need to be cleaned. Typically, these are rejected tubes, for example, rejected because of a metal part added beforehand.
In automatic mode, there is no need to display the optimal or enhanced path to the operator.
According to a third embodiment of the method, entirely automatic, a robot controlled by an algorithm can carry out the movements (Dca) of the rod along the axes x1 and y1 by following the order defined by the optimal or enhanced path, as well as the movements Dch of the rod along the axis z1. In automatic mode, there is no need to display the optimal or enhanced path to the operator, and therefore there is no longer a recovery need.
In practice, in automatic and semi-automatic modes, the robot positions the orthogonal comparison marker (x1, y1, z1) in relation to the orthogonal reference marker (x0, y0, z0), such that the hose is arranged opposite an orifice, marked and defined by the optimal or enhanced path defined by the second calculator
Advantageously, the method according to the embodiments can further include, after each step G, an additional step of interacting with the operator or the second calculator with the enhanced image.
By interaction, it is meant in the sense of some embodiments, adding optional information which could help the operator or the second calculator, to form a new enhanced image serving as a reference during the carrying out of a new step G in view of cleaning a new orifice. This optional information can typically include any type of information that the operator responsible for the cleaning of the tubes wants to capitalize on, and which can be compiled in the cleaning report at the end of the operation: for example, the indication of the rejected holes, or holes of which the cleaning has not been able to be carried out correctly and which may require cleaning with another rod, or the history of the different cleaning steps carried out. The new enhanced, modified image can be stored in view of guaranteeing the traceability of the process by representing the initial status of the exchanger before each processing (steps E to I).
Embodiments of the present invention will now be described in detail with reference to the accompanying drawings in which:
Other advantages and specificities of the present embodiments will emerge from the description which will follow, given as a non-exhaustive example and made in reference to the appended figures and to the corresponding examples:
An example of an implementation of the method according to some embodiments is defined below using
The heat exchanger 2, represented in
An orthogonal reference marker (x0, y0, z0) is virtually connected directly and three-dimensionally to the support plate 22, such that the axes x0 and y0 thereof are contained in the plate 22 plane (or in a plane which itself is parallel) and the axis z0 thereof is substantially horizontal. Likewise, an orthogonal comparison marker (x1, y1, z1) is virtually connected directly and three-dimensionally to the cart 3, such that the axis z1 thereof is parallel to the symmetry axis of the rod 11, as illustrated in
Further to the rigid cleaning rod 11 arranged on the cart 3, the cleaning device according to some embodiments further includes the following components:
These components are chosen to function in the external environment.
Moreover, to avoid uncontrolled surrounding light, a dedicated lighting and a spectral filtering at the level of the camera (e.g. NIR @ 850 nm) (not visible to the naked eye, but visible by the camera), leading to the obtaining of a monochrome image. Advantageously, a monochrome, digital, 16-Megapixel (4096×4096) camera will be used, enabling to obtain a real image with a spatial resolution of less than 1 mm/pixel.
These graphic representations are indeed three-dimensional models produced by the CAD software, “SolidWorks”, illustrating the distancing of the camera 4 in relation to the center of the heat exchanger 2.
In particular,
In the case of a lateral positioning of the camera 4 at around 1 m from the center of the support plate, as shown by the photograph in
With a recovered display, such as shown by
From the high-resolution real images 50 thus obtained (between 0.5 and 1 mm/pixel), possibly recovered 51, and with the use of NIR lighting ensuring a certain independency in relation to the surroundings, a first calculator generates high-resolution monochrome images (enhanced images), that can be used for the automatic detection of the tubes and the stoppers.
Given the great disparity in heat exchangers, and without knowing the state of the surface before cleaning (for example, holes blocked with a rather clear material), the search algorithm of the tubes of the method according to some embodiments will be based on the fact that light does not enter or hardly enters the tubes, and therefore, the processing will search for local minima in the image.
To enhance this step of the method of the embodiments, it is advantageous to stick reflective dots 5 of a known size (at least 3) on a face of the exchanger (coplanar points), as illustrated in
The enhanced images 52 generated by the first calculator include a first visual marking 210 of the tube orifices to be cleaned (marked orifices): in
To complete the remote visualization system previously defined, and to enable the automatic positioning of the bundle cleaner opposite the tube orifices 21, model objects can advantageously be used, of which the geometry is known, and of which the position and the orientation on the images taken with lighting of a known wavelength will be searched to be detected (preferably or possibly in the near-infrared at 850 nm) and a spectral filter on this wavelength at the level of the camera.
More specifically, as model objects, two luminous target objects 6, 7 can be advantageously used:
Such target objects are schematically represented in
These objects 6, 7 are comprised of or include target points 61, 62, 63, 64, or 71, 72, 73, 74, which are either passive (able to reflect light), or active (emitting light, for example, LEDs).
The target points 61, 62, 63, 64, 71, 72, 73, 74 reflect light coming from the same direction as the line of view of the camera 4. Only light reflected by the targets 6, 7 is captured by the camera 4.
Lighting of a known wavelength (for example, in the near-infrared at 850 nm) and a spectral filter on this wavelength at the level of the camera enabling to avoid the changes in light surroundings (for example, effects from the sun).
An example of an image obtained by such a system is shown in
In practice, tracking and a 3D measurement of the position of the 2 target objects 6, 7 are made (
It is understood, in the framework of the present embodiments, that one same camera can be used for detecting tube orifices and for that of target objects. But, it is also possible to use two separate cameras.
By a calibration and construction mechanism of the initial model, it is then possible to construct a 3D model of the positions of the orifices 211, 212 of the tubes 21 of the exchanger 2, in order to assist the user or the robot in the positioning of the cleaning device in relation to the support plate 22 of the exchanger 2.
Positioning and Calibration
An advantage of using target objects 6, 7 is that there is no high limitation for the positioning of the rod 11 from the time when the two target objects 6, 7 are in the visual range of the camera.
The target objects 6, 7 can be protected from splashes by their positioning. These objects must or should simply be connected to the equipment (exchanger 2, or cart 3) whereon they are positioned.
The deployment of such a system is quick (less than 15 minutes). If the exchanger 2 moves during cleaning, the camera will track it, will give an alert and can even, during a reasonable movement (of a few centimeters), proceed with correcting the alignment, whether for the operator in manual or semi-automatic mode, or for the calculation device of the trajectory of the hoses in a completely automatic mode (notion of ongoing recalibration of the alignment, whatever the movement of an element in relation to another).
In practice, the calibration phase consists of or includes positioning the bundle cleaners along the 4 cardinal points in relation to the exchanger 2 and capturing a measurement at each position. By then entering the geometry of the different tubes 21, the system is self-calibrated, and is capable of knowing the position that the model must or should be in to be opposite the tubes 21. This geometry can come from information entered by the operator using simple tools, by using an image, for example, and/or the automatic detection of tubes 21. It is thus possible to project the current position of the bundle cleaners 1 on a mesh of virtual or real tubes (image coming from the other system).
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| 20180172372 A1 | Jun 2018 | US |
