EP3757504B1 - Device for high-pressure cleaning of the pipes of a heat exchanger and method using this device - Google Patents

Description

The invention relates to an automated device for high-pressure cleaning of the tubes of a heat exchanger using water or another suitable cleaning liquid under high pressure, and to a method using this device.

Such heat exchangers are also referred to as tube bundle apparatus. A heat exchanger has a mirror into which a large number of tubes arranged parallel to one another open. The mouths of the tubes are arranged in a regular structure. There is a two-dimensional periodicity within certain ranges. On the one hand, however, this regularity extends only over a certain area or certain areas. It only extends as far as one edge of the heat exchanger, where flange bores arranged on a circular arc are generally also provided in the mirror. Furthermore, there are often strips in the interior of the mirror in which no openings are provided. Over time, pipes fail, for example because they leak or are clogged in a manner that cannot be cleaned, the mouths of these pipes are usually closed, welded or otherwise made inaccessible. In a purification, therefore, one can only rely on the periodicity to a certain extent. It is necessary to detect each individual active orifice, i.e. to know its x-y position, and to exclude passive areas, edge areas and inactive orifices. This represents a significant requirement in hand cleaning, as is currently the practical state of the art. The inner diameters of the tubes are usually not different from each other. The mouths lie in one plane, the x-y plane.

High pressure means a pressure of the cleaning liquid used of at least 25 bar, but in particular at least 100 and preferably at least 500 bar. Water is preferably used as the cleaning liquid. At the high pressure values, the water jets emerging from a nozzle have such a high momentum that they mechanically remove impurities from the inner walls of the heat exchanger tubes. As a rule, water without additives is used, in any case additives are avoided as far as possible. While it is possible that the water cleaning additives, for example abrasives or sand, are added, but this has a disadvantage, because abrasives and sand, for example, further reduce the already short service life of the nozzles.

Efforts are made to keep personnel involved in high-pressure cleaning as far away from the actual cleaning site as possible. At the high pressures used, serious injury can occur if something goes wrong.

According to the current state of the art, pneumatically operated motors are used to move the positioning device. Due to the high water load, efforts are being made to avoid using electrical units as far as possible. Motorized positioning devices for cleaning heat exchangers are part of the prior art, reference is made to DE 10 2015 218 114 B4 , DD 255 202 A1 and US4095305A . Out of U.S. 2009/255557 A1 an automated cleaning device is known. A motorized positioning device, a high-pressure unit, several cameras and also a control unit are known from it. The high-pressure unit works with several parallel lances. The cameras are used for general surveillance, their respective images are displayed on screens in a control panel. In order to be able to adjust the correct positioning of the lances to the mouths in the mirror, an auxiliary part is used, which is made of plastic, for example, with this auxiliary part the mechanical positioning is achieved. Out of DE 691 04 934 T2 a high-pressure unit is known, as is similarly used in the present invention. There are no displacement sensors for the hoses.

document US2017/0016687 discloses a device for automated high-pressure cleaning of the tubes of a heat exchanger according to the preamble of claim 1.

The object of the invention is to avoid the disadvantages of the previously known devices and the previously known methods and to further improve them to the effect that the work processes are safer and easier to carry out, a light and essentially compact device is obtained that can be easily transported to different locations can and enables safe working.

This object is achieved by a device having the features of claim 1.

The use of electric motors, preferably electric motors designed as stepping motors, enables precise positioning of the respective carriage reached along the associated axis. Such accurate positioning is not achievable with pneumatically or hydraulically powered motors. The electric motors are sufficiently encapsulated, for example IP6K, so that work can be carried out safely under the given conditions. All electrical parts are preferably operated with low voltage, in particular below 48 V.

Positioning in the starting position, also known as the reference position, is made possible via the zero sensors. There x = zero and y = zero. An orthogonal x-y-z system is preferably used. Other coordinate systems, for example with polar coordinates, are possible. The two zero sensors are preferably identical in construction. Inductive sensors can be used. The sensors preferably have a first, active part, which has electrical connection lines and is fixed in a stationary manner on an axis, and a second, passive part, for example a reference surface, which is attached to the movable carriage.

It had proven to be very advantageous to provide the x-axis and the y-axis with a toothed rack over their entire length. The electric motors then engage in the rack via a pinion. As a result, precise positioning is achieved overall. It is then possible to additionally detect a positioning in the direction of the respective axis via a proximity sensor that is assigned to the toothed rack.

In a known manner, the guide unit has the task of guiding the hoses parallel to the z-axis and at a distance from one another. This makes them parallel to the axes of the tubes. The distance between the individual hoses in the guide unit can be adjusted. Individual hoses can also be removed from the guide unit. The displacement sensors, which are each assigned to a hose, are preferably arranged inside the guide unit.

There is a lower stop for each high-pressure hose between the guide unit and the mirror of the heat exchanger. It ensures that the hose cannot be pulled out of the guide unit. It is positioned in such a way that when it hits the guide unit, the nozzle that forms the end of the high-pressure hose is free of the mirror. Furthermore, an upper stop is provided, which is located on the other side of the guide unit. It is adjustably connected to the guide hose. He's going to lengthen it positioned equal to the length of the pipes plus an allowance. If this upper stop comes into contact with the guide unit, the nozzle is at the bottom of the pipe. The detection of the path by means of the path sensors can be reset to zero in each case via the described contact of the stops, in particular the lower stop. Especially at the beginning of a new shift or a new cleaning task, the path measurements are set to zero, then the hoses are in their uppermost position, the lower stops are in contact with the guide unit. The stops can also interact with other components that are stationarily connected to the guide unit.

The camera has an optical axis parallel to the z-direction. She looks at the mirror at a right angle. When the optical axis of the camera is positioned exactly over the mouth of a pipe, the mouth of the pipe is imaged as a circle. On the other hand, those in the peripheral area of the image captured by the camera are represented as ellipses. In order to make it easier to recognize the pipe openings in the edge area as well, the opening angle of the camera is preferably limited, for example to a cone angle of a maximum of 30°, preferably a maximum of 20°. As a rule, this leads to a large number of partial images being recorded by the camera. Since the camera is fixed on the z-axis, the position of the optical axis is known. The x-y position of the camera can thus be assigned to each partial image. This significantly simplifies the combination of the partial images to form the desired overall image. Neighboring partial images usually overlap.

It is advantageous to connect the camera to the z-axis in a removable manner. Then there is an opportunity to remove them before starting the cleaning process. Alternatively, the camera can be covered with a special protective device as soon as it is no longer needed and before the cleaning process begins.

The control unit is preferably equipped with a computer (data processing system). It is electrically connected to all of the described active components via connections. The signal from the camera is recorded in the control unit and processed there. It is evaluated and evaluated there and the combined image is created, on the basis of which it can then be calculated in a second calculation step how the pipe mouths actually found It is best to first clean with three hoses, then the remaining ones with fewer hoses.

It turned out to be advantageous if the camera, which has an optical axis, is aligned in such a way that the optical axis runs parallel to the z-axis. The camera then looks directly into the mouth of the pipe below it on the optical axis. The pipe mouths lying in a peripheral area of the image of the camera are viewed at an angle. This angle is between the optical axis and the ray connecting the camera to the pipe mouth under consideration. Such pipe mouths appear in the picture as an ellipse. Since the optical axis runs at right angles to the mirror, pipe mouths in one edge area of the image appear as deformed ellipses, as do pipe mouths in the opposite edge area with respect to the optical axis. The angle should preferably not be too large. The ellipse should not deviate too much from the circular shape. The ratio of major axis to minor axis should be no less than 1:2, preferably no less than 1:1.3. This makes it easier to identify the pipe openings in the edge areas. The evaluation of the camera can be designed accordingly. If it recognizes ellipses that deviate even more from the circular shape, it can sort them out.

It is also possible for the tube mirror to have a first set of tubes with a first diameter and a second set of tubes with a second diameter. The device can be adapted to this situation; it is preferably input in advance that a first set is scanned first, the data of which is given, followed by the second set.

Furthermore, the object is achieved by a method according to claim 8.

For high-pressure cleaning, a mirror is first clamped into the device. The rows of holes in the pipe mouths are aligned as far as possible parallel to at least one of the x-axis and y-axis. Subsequently, several partial images of the mirror are preferably recorded by the camera and forwarded to the data processing system. The respective xy position of the camera for each sub-image is recorded and assigned to the sub-image. As a result, an image of the mirror can be calculated in the data processing system. The mirror is preferably scanned linearly. Preferably, the individual sub-images are subjected to histogram equalization in order to inhomogeneous to balance lighting. The sub-images are preferably assembled by means of 2D correlation of the overlapping sub-images. A binary image is preferably created from the entire image obtained by adapted filtering. All contours in the image are then preferably interpolated as circles, which are then examined according to their radius and filtered using a threshold value. As a result, only those circles are recorded that match a mean radius of the mouths within a specified deviation. Preferably, only those shapes are detected as circles that have a transverse dimension to longitudinal dimension ratio that is within the range of the ellipses that the camera captures in the image.

It is advantageous for the data determined in this way by the data processing unit (by the computer) to be displayed visually so that an operator can check them. He can then preferentially add missing pipes or remove incorrectly recognized pipes.

When all pipe positions are known, the coordinates for the positions of the hoses are determined. The standard configuration consists of three hoses or nozzles arranged parallel to one another and aligned next to one another in a straight line. A favorable way is now calculated in the data processing system as to how the groups of the individual pipe mouths can be approached one after the other.

The length of the tubes of the heat exchanger to be cleaned is known. It is usually entered into the control unit by the operator. This can now calculate and display the cleaning time for the selected arrangement.

After the camera has been dismantled, the actual cleaning process with high-pressure water can now be started. The cleaned pipes can be visualized on a screen of the control device. After the cleaning is finished, this will be displayed on the screen.

The control device is preferably arranged at a greater distance from the positioning device. As a result, it is largely protected. It is preferably housed in a separate cabin.

The control unit can have a second, mirrored operator panel in the form of a tablet that is wirelessly connected to it.

The process can preferably be aborted by a user at any time, for example in the event of an irregular operating state (interrupted operation). The cleaning process is stopped, the high-pressure pump is switched off, the hoses are completely pulled out of the pipes of the heat exchanger up to the bottom stop, the electric motors are no longer activated, but the carriages remain in the respective position. The operator can now move the slides manually, refer to them again, continue the cleaning process, or make changes, e.g. enter changes to the pipes to be cleaned or the cleaning path. The pipes that have already been cleaned remain saved. When the system moves on, the entire cleaning process continues from where it stopped. Pipes that were being cleaned at the time of the interruption are cleaned again. The changes entered by a user during the break are taken into account.

1. a) Referenzfahrt der beiden Achsen und
2. b) Scannen des Spiegels.

Furthermore, there is preferably the "emergency stop" state. Here, the cleaning process is stopped, the high-pressure pump for cleaning water is switched off and all electrical power consumers except for the control unit are de-energized. The latter remains live, so that the following actions must be carried out after restarting:

1. a) Homing of the two axes and
2. b) Scanning the mirror.

After restarting, the pipes that have not yet been cleaned are approached and cleaned with the same restrictions as with interrupted operation.

The device and the method offer the advantage that the control unit is currently informed about the position of the z-axis relative to the mirror and about the current position of each individual high-pressure hose relative to the guide unit. The device can be made relatively light, for example with a total weight of less than 30, preferably less than 20 kg (without the hoses and the high-pressure pump). It can thus be brought to different locations without major aids. The danger to people from high-pressure water is largely excluded, since an operator does not have to come into contact with the actual cleaning process.

Further features and advantages can be found in the subclaims.

Fig. 1

eine Draufsicht (in negativer z-Richtung) auf die Vorrichtung und einen mit der Vorrichtung verbundenen Spiegel eines Wärmetauschers mit zwei Gruppen von Rohrmündungen,

Fig. 2

eine Draufsicht auf eine Hochdruckeinheit mit drei Schläuchen, Blickrichtung ist die negative y-Achse,

Fig. 3

eine schematische Darstellung eines Wegsensors.

An exemplary embodiment of the device is explained and described in more detail below with reference to the drawing; this exemplary embodiment is not to be understood as limiting. Show in the drawing:

1

a top view (in the negative z-direction) of the device and a mirror of a heat exchanger with two groups of tube openings connected to the device,

2

a top view of a high-pressure unit with three hoses, viewing direction is the negative y-axis,

3

a schematic representation of a displacement sensor.

In the different figures, parts that are equivalent in terms of their function are always provided with the same reference symbols, so that they are usually only described once.

A right-hand orthogonal x-y-z coordinate system is used for the description. This corresponded to the coordinate system on which the device to be described is based and according to which it works.

figure 1 shows a plan view of a mirror 20 of a heat exchanger. It has a first set of tube openings 22 with tubes 24 of a first diameter in an upper area, and a second set of tube openings with tubes of a second diameter is shown in the lower area. For both sets, not all the pipe mouths are shown, rather only a selection from the large number of pipes that more or less completely fill out the corresponding fields.

The mirror 20 has flange bores 26 in a known manner. Like the pipe mouths 22, these are round, but must not later be recognized as a pipe mouth. They have a different, here larger diameter than the pipe mouths and are sorted out later as areas not to be cleaned based on their larger diameter. In addition, they can be recognized as irrelevant because they are in the absolute vicinity of the edge of the mirror 20 and/or lie on an arc of a circle.

The mirror 20 is mechanically fixed in a known manner, not shown here, to a motorized positioning device. This device is discussed below. It has two mutually parallel x-axes 28 of identical construction. These are mechanically firmly connected to the mirror 20 . Preferably are assigned to them along the entire length of racks, not shown. An x slide 30 is guided in a freely displaceable manner on each x axis 28 . An x electric motor designed as a stepping motor is used to move it. It engages the rack with a pinion (not shown). A balancer shaft (not shown) preferably connects the two x-axes 28 so that the two x-carriages 30 are always moved and positioned synchronously.

On each in the figure 1 A first, active part 34 of an x=zero sensor is arranged at the right end of the x-axes 28 . It works together with a passive, second part 36 . The part 34 is designed, for example, as an inductive proximity sensor. Accordingly, there is a two-part max sensor with the active part 38 and the passive part 40 at the left end of the x-axes 28.

The passive parts 36, 40 are each attached to the associated x-carriage 30, the active parts 34, 38 are stationary, which simplifies their electrical connection.

The two x-carriages 30 are connected by a y-axis 42, the y-axis 42 is carried by them and moves with them. In a manner analogous to each x-axis 28, a y-carriage 44 is guided freely displaceably on the (single) y-axis 42; it is preferably identical in construction to the x-carriage 30 electric stepping motor, driven here by the y-electric motor 48. Here, too, a drive via a pinion that engages in a toothed rack of the y-axis 42 is advantageous.

The y-axis 42 is equipped with sensors, as is each x-axis. They are identical to the x-axis sensors. Specifically, there are the components 48, 50, 52 and 54, see also the list of reference numbers.

The y-carriage 44 is mechanically firmly connected to a z-axis 56, which it carries.

Only part of a high-pressure unit is connected to the z-axis. The high-pressure unit has in the embodiment shown, see also figure 2 , three high-pressure hoses 58, also called hose for short. This high-pressure unit includes a base unit 60. In a known manner, it has a reel for the individual hoses 58. In the base unit 60, the first ends of the hoses 58 are connected to a high-pressure source. The base unit 60 has a motor drive device for propulsion and/or for the return movement of each one hose 58. The base unit 60 does not belong to the part of the high-pressure unit which is connected to the z-axis 56.

The hoses 58 each carry a nozzle 61 at their other end in a known manner. The hoses 58 and the nozzles 61 are preferably of identical construction.

A guide unit 62 also belongs to the high-pressure unit. It is detachably connected to the z-axis 56 . The three hoses 58 are guided in it, and there are three guide channels 64 for this purpose. The distance between these guide channels can be varied, so that the pipe mouths 22 can be adjusted to different geometrical arrangements, in particular periodicity. A window is provided in each case in the area of the guide channels 64, where the respective hose is freely accessible for and in the field of vision of a displacement sensor 66. The displacement sensors 66 are described with reference to FIG figure 3 described in more detail below.

A lower stop 68 surrounds each tube 58 . He is how figure 2 13, abutting the guide assembly 62 when the hoses 58 are fully retracted, like this figure 2 shows. This position is also the zero or reference position from which hose movement is captured and measured. Upper stops 70 are connected to the hoses 58 on the other side of the guide unit 62 . When in abutment on the other side of the guide assembly 62, the hoses 58 are fully extended, adjustable to the maximum length of pipe to be cleaned. Accordingly, the position of the upper stops 70 can each be adjusted to suit the heat exchanger to be cleaned. The lower stops 68 can also be adjustable. According to figure 2 the upper stops 70 are at a distance d from their stop, which is formed here by the guide unit 62. The dimension d is the sum of the clear distance between the nozzle 61 and the mirror 20 plus the length of the pipes 24 to be cleaned. The stops 68, 70 can also interact with other counter-stops than with the guide unit 62.

A camera 72 is detachably connected to the z-axis 56 . Its optical axis runs parallel to the z-direction, i.e. to the z-axis 56. The opening angle of its optics is selected such that pipe mouths 22 captured in the edge region of an image by the camera 72, which appear as an ellipse in the image, do not appear as an ellipse that is too flat . Pipe openings 22 lying in a peripheral area of the image of the camera should lie at an angle of less than 30°, preferably less than 20° and in particular less than 15° to the optical axis of the camera. Since the camera 72 detachable with connected to the z-axis 56, it can be removed prior to performing an actual cleaning operation. A protective device can also be provided for the camera 72 so that it does not have to be removed.

Finally, the device has a control unit 74. All active components of the device are connected to it via connections 75, in particular the camera 72, the high-pressure unit with its drives and the displacement sensors 66, all electric motors and all sensors. The control unit 76 controls the electric motors and is informed about the current position of the individual slides via their stepping function. It controls the process, as can also be seen from the following description of the process.

The path sensors 66 are described in detail below. Tracking sensors 77 are used, e.g. from PixArt, which can detect the speed of an object moving parallel to the sensor, and only the speed of an object moving parallel to the respective sensor, in this case one of the hoses 58. All three tracking sensors are housed in a sensor housing 76 . It is completely and tightly closed off on its lower side, which faces a hose 58 through a window in the guide channel 64, by a viewing pane 80, for example made of acrylic glass. In front of it is a dirt screen with openings for the sensor viewing areas. The space between the pane 80 and the dirt screen is aerated with flushing air under pressure, so that flushing air constantly escapes from the holes in the dirt screen, which prevents water droplets or dirt particles from penetrating. The measured speeds of the individual hoses 58 are used in the control unit 74 to calculate and monitor the feed path of the hoses 58 .

A regular cleaning procedure is described below:
After the installation has been completely assembled, which also includes the connection of the two x-axes 28 to the mirror 20, the two electric motors 32, 46 are actuated, they are moved to the zero position. This is recognized in that the zero sensors 34, 36, 48, 50 emit a speaking output signal via one of the connections 75 to the control unit 74. If necessary, the max sensors are also approached. Furthermore, it is determined whether the lower stops 68 are in contact with the guide unit 62, in this way the control unit 74 learns via the associated connection 75 that the path measurement by means of Displacement sensors 66 is in the zero position. It is advantageous to accommodate proximity sensors for the lower stops in the guide unit 62, which are identical in construction to the sensors of the axles. Thereby, the state of contact of each lower stopper 68 with the guide unit 62 can be detected by the control unit 74 .

A complete scan of the surface of the mirror 20 now takes place. The camera 72 is used to acquire partial images. The camera has an object field of about 300 × 300 mm. Starting from the position x=zero and y=zero, the x carriages are each moved by approximately 280 mm in the positive direction of the x axis 28 and an image is recorded approximately every 280 mm. The y-carriage is then moved along the y-axis 42 by approximately 280 mm and then the next line is correspondingly scanned by shifting the x-carriage in the opposite direction, etc. This is done until the bottom row of images has been acquired.

The current position of the camera with x-coordinate and y-coordinate is assigned to each individual image. The individual images are subjected to histogram equalization and combined to form a complete image by means of 2D correlation of the overlapping partial images.

A binary image is created from this entire image by adapted filtering. All contours in this binary image are then interpolated as circles. The dimension of the large semi-axis of an ellipse is retained. Here it is possible to only allow ellipses to be reshaped into circles that do not exceed a certain ratio of the major to the minor axis. After that, the circles obtained are examined by radius and filtered by means of a threshold value. Here it is possible to use preferably those flange bores for determining the threshold value that are located directly on or at least in the area of the optical axis of the camera.

The presumed positions of the pipe mouths 22 are displayed in a user device (tablet) and on a monitor. This gives the operator the option of adding missing pipes, removing or correcting incorrectly recognized positions, for example pipes that have been welded shut.

When all pipe positions are known, the coordinates for the position of the nozzles 61 are calculated. Initially, the normal configuration is started with three hoses 58 arranged parallel to one another. It will now appear on the picture Displayed on the monitor and marked which pairs of three can be cleaned in this way. A favorable path between the individual groups of three is calculated. The guide unit 62 will be moved along this path during the cleaning. Individual pipe mouths 22 remain, which can only be reached in pairs or only as individuals. A data processing system 78 of the control unit 74 now calculates whether it is more favorable to initially work in an arrangement with two hoses 58 and then to clean the remaining pipes 24 with a single hose, or whether it is more favorable to clean all the remaining pipes 24 with a single hose . With her, only a conversion, which must be carried out by the operator, would be necessary.

The operator must enter the length of the tubes 24.

The respective durations of the cleaning steps are calculated for the individual pairings and paths. The operator is given the opportunity to decide which path arrangement should be used to clean the heat exchanger. Among other things, the fastest cleaning is offered.

Now the actual cleaning process can be started. The cleaned pipes are visualized on the screen. A message is also sent after the cleaning has been completed, and a log is issued. The device can work independently during this time.

If it is determined during cleaning that a pipe 24 is clogged, the depth of penetration of the nozzle 61 into the relevant pipe 24 determined via the respective displacement sensor 66 is stored. The corresponding tube is shown as not cleaned in the log. If other tubes 24 are also being cleaned at the same time, as is the case, for example, with a pair of three, their cleaning process is carried out and they are shown as cleaned if they can be cleaned. This is made possible by the fact that the drive of each individual tube 58 in the base unit 60 acts on the tube with a certain fiction, so that the drive continues to work, but no longer drives the tube forward. This does not affect the other hoses in the pairing. It is also possible to switch off the drive of a hose 58 in question if a threshold value of a propulsion force is exceeded.

Special procedures may be used to clean a tube 24 that is not easy to clean. For example, one oscillating movement of the hose 58 are performed in the area of the blockage.

The same procedure is followed for the cleaning of the second set of tubes 24 . It may be necessary to replace the guide unit 62 beforehand, and thinner hoses 58 and thus a different base unit 60 may also have to be used.

Terms such as essentially, preferably and the like, as well as information possibly to be understood as imprecise, are to be understood in such a way that a deviation of plus/minus 5%, preferably plus/minus 2% and in particular plus/minus one percent from the normal value is possible. The applicant reserves the right to combine any features and also sub-features from the claims and/or any features and also partial features from a set of the description with other features, sub-features or partial features in any way, even outside of the features of independent claims. The applicant also reserves the right to delete any features or partial features.

The device for automated high-pressure cleaning of the tubes 24 of a heat exchanger with a) a motorized positioning device, which has a an x-axis 28, b an x-carriage 30 that can be moved along the x-axis 28 by means of an x-electric motor 32, c an x=zero Sensor 34, 36, d a y-axis 42 carried by the x-carriage 28, e a y-carriage 44 that can be moved along the y-axis 42 by means of a y-electric motor 46, e a y=zero sensor 48, 50, and has a z-axis 56 carried by the y-carriage 44, and b) a high-pressure unit with more than one high-pressure hose 58, with a displacement sensor 66 assigned to each high-pressure hose 58 for detecting the hose movement, with a guide unit 62, which is attached to the z- Axis 56 is arranged, each with a lower stop 68 for each high-pressure hose 58 and each with an upper stop 70, which is preferably arranged on the opposite side of the nozzle 61 of the guide unit 62, has c) a camera 72, which is on the z Axis 56 is detachably arranged, and d) a control unit which is connected to the camera 72, the high-pressure unit, the electric motors 32, 46, the displacement sensors 66 and the zero sensors 34,36, 48,50 and to which a data processing system 78 belongs.

Reference List

20

Mirror

22

pipe mouth

24

Pipe

26

flange drilling

28

X axis

30

x carriage

32

x electric motor

34

x=zero sensor (first part)

36

second part of 34

38

x=max sensor (first part)

40

second part of 38

42

y-axis

44

y slide

46

y electric motor

48

y=zero sensor (first part)

50

second part of 48

52

y=max sensor (first part)

54

second part of 50

56

z-axis

58

high pressure hose

60

base unit

61

jet

62

Guide unit

64

guide channel

66

displacement sensor

68

lower stop

70

upper stop

72

camera

74

control unit CON

75

electrical connection

76

sensor housing

77

tracking sensor

78

data processing system

80

disc

Claims (13)

1. A device for the automated high-pressure cleaning of the pipes (24) of a heat exchanger, which comprises a mirror, with

   - a motor-driven positioning device, which comprises a) x-shaft (28), b) an x-carriage (30) displaceable along the x-shaft (28) by means of an x-electric motor (32), preferably a stepping motor, c) a y-shaft (42) carried by the x-carriage (28), d) a y-carriage (44) displaceable along the y-shaft (42) by means of a y-electric motor (46), preferably a stepping motor, and a z-shaft (56) carried by the y-carriage (44),

   - a high-pressure unit with more than one high-pressure hose (58), preferably with three high-pressure hoses (58), which can each be connected at one end to a high-pressure source and at their other end carry a nozzle (61), with a position sensor (66) assigned to each high-pressure hose (58) for detecting the hose movement, with a guide unit (62), which is arranged on the z-shaft (56) and accommodates the high-pressure hose (58),

   - a camera (72) which is arranged on the z-shaft (56), and

   - a control unit, which is connected to the camera (72), the high-pressure unit, the electric motors (32, 46) and the position sensors (66) and to which a data processing system (78) belongs,

   characterised in that

   - the motor-driven positioning device comprises an x=zero sensor (34, 36) and a y=zero sensor (48, 50), wherein the control unit is connected to the zero sensors (34, 36, 48, 50),

   - the high-pressure unit in each case comprises a lower stop collar (68) for each high-pressure hose (58), which is arranged between the nozzle (61) and the guide unit (62),

   - the high-pressure unit in each case comprises an upper stop collar (70), which is preferably arranged on the side of the guide unit (62) lying opposite the nozzle (61), and

   - the camera (72) is arranged detachably on the z-shaft (56).
2. The device according to claim 1, characterised in that the x=zero sensor is in two parts, wherein a first part (34) is arranged on the x-shaft (28) and a second part on the x-carriage (30), and/or that the y=zero sensor is in two parts, wherein a first part (48) is arranged on the y-shaft (42) and a second part (50) on the y-carriage.
3. The device according to any one of the preceding claims, characterised in that the lower stop collar (68) is arranged between the nozzle (61) and the guide unit (62), and that the upper stop collar (70) is arranged on the side of the guide unit (62) lying opposite the nozzle (61), and that at least one of the stops is constituted displaceable along the respective high-pressure hose (58).
4. The device according to any one of the preceding claims, characterised in that the positioning device further comprises an x=max sensor (38, 40) and a y=max sensor (52, 54) which are connected to the control unit (74), and that these two sensors are preferably structurally identical to the sensors according to claim 2.
5. The device according to any one of the preceding claims, characterised in that a software program for image processing and a software program for the control of the electric motors (32, 46) are contained in the control unit.
6. The device according to any one of the previous claims, characterised in that the optical axis of the camera (72) is aligned parallel with the z-axis.
7. The device according to any one of the previous claims, characterised in that a partial area of the mirror (20) detected by the camera (72) is selected, such that pipe mouths (22) lying in the edge region of the image of the camera (72) lie at an angle less than 30°, preferably less than 20° and in particular less than 15° to the optical axis of the camera (72).
8. A method for the automated high-pressure cleaning of the pipes (24) of a heat exchanger by means of a device according to any one of the preceding claims and the following process steps:

   A. Taking of at least one photograph with the camera (72) of the mirror (20) of the heat exchanger, wherein the mirror (20) is connected to the positioning device,

   B. Analysis, assessment and completion of a computer-readable image of the mirror (20) from the latter,

   C. Calculation of a cleaning route, along which the guide unit is moved in the x-y-plane and the nozzles (61) are assigned to adjacent pipes (24) of the heat exchanger to be cleaned, in the data processing system (78) and with the aid of the image,

   D. Carrying out cleaning of individual preferably adjacent pipes (24), wherein the penetration depth of the nozzles (61) into the pipes (24) is detected by the position sensor (66) which is assigned to the respective high-pressure hose (58), and

   E. Issuing of a record of the cleaning that has taken place, wherein the carriage (30, 44) is displaced into a position before step A., in which both zero sensors (34, 36, 48, 50) display a stop in the x=zero and the y=zero position of the positioning device.
9. The method according to claim 8, characterised in that a plurality of partial images of the mirror (20) are compiled in step A., wherein at least two partial images each partially overlap and for each partial image the x-y-position is detected and assigned, and that in the data processing system (78) the partial images are combined to form a whole image of the mirror (20).
10. The method according to any one of the preceding claims, characterised in that the assessment takes place in step B., in such a way that the radii of the detected pipe mouths (22) of the pipes (24) are assessed and only such elements present in the image of the heat exchanger are assessed as pipe mouths (22) which lie in a predetermined deviation range with respect to the central radius.
11. The method according to any one of the preceding claims, characterised in that a first cleaning route is first calculated in step C., in which all the high-pressure hoses (58) guided in the guide unit (62) are used, that a second cleaning route is then calculated, in which a sub-total of the high-pressure hoses (58) guided in the guide unit (62) is used and the others are passive or are removed.
12. The method according to any one of the preceding claims, characterised in that, when it is established in step D. by the position sensor (66) that at least one nozzle (61) is not inserted up to the full length of the pipe (24) to be cleaned, but at a certain depth no longer advances, the cleaning process for this pipe (24) is terminated and this pipe (24) is stated in the record according to step E. as not cleaned.
13. The method according to any one of the preceding claims, characterised in that, before step A., the hoses (58) are moved into the position in which the lower stop (68) is in contact with the guide unit (62), and that the detection by means of the position sensors (66) is set to zero in this state.

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