GB2507120A

GB2507120A - Apparatus and method of cleaning tubes

Info

Publication number: GB2507120A
Application number: GB1218902.3A
Authority: GB
Inventors: Michael Watson
Original assignee: Tube Tech International Ltd
Current assignee: Tube Tech International Ltd
Priority date: 2012-10-22
Filing date: 2012-10-22
Publication date: 2014-04-23
Also published as: GB201218902D0

Abstract

Apparatus for removing scale from an outer surface of a tube 50 comprises an annular collar 10 formed of at least two parts assembled around the tube. The collar has cleaning elements for scraping or impacting an outer surface of the tube when the collar is rotated about a longitudinal axis of the tube. A carriage 30 displaces the collar parallel the tube longitudinal axis and carries a motor 36 that applies torque to rotate the collar about the tube. The carriage may comprise of two or more parts and include rollers 33 engaging the outer surface of the tube, and may be advanced along the longitudinal length of the tube by a pulley system or may be self propelled. The carriage may include motor driven wheels frictionally engaging the outer surface of the tube, and may include two bands 32, 34 that grip and release the tube and are spaced longitudinally axial of the tube using a motor or hydraulic system changing the axial distance between the bands. Aggressiveness of the cleaning elements may be provided by adjusting the collar, which may be set remotely by an operator. Cleaning may be monitored by a camera mounted on the carriage.

Description

METHOD AND APPARATUS FOR CLEANING TUBES

Field of the invention

The presenc invention relates to the cleaning of the outer surfaces of tubes, in particular furnace tubes.

Background of the invention

In an industrial furnace used to heat a process liquid, the process liquid flows through an array of heat exchange tubes arranged within the combustion chamber of the furnace.

The tubes are large diameter tubes, for example locms or more, and may extend to a height of several metres. The burning of fuel in the combustion chamber of the furnace coats the tubes with a scale which, if allowed to build up excessively, reduces the thermal transfer efficiency of the hoat cxchangcr. It is thorcforc nocoosary to rcmovo thc scale periodically.

Cleaning of furnace tubes has hitherto been performed by an operator scraping or chipping off the hard scale manually or by using a high pressure lance to dislodge the scale. However, for an operator to gain access to the tubes over their entire length, it was first necessary to construct a scaffolding. As a result, the cleaning operation has been lengthy and labour intensive. As well as adding to the cost of cleaning, the length of time involved also increases the down time of the furnace, which adds further to the total cost.

Object of the invention The presenc invention seeks to provide a method and apparatus that allow furnace tubes to be cleaned more quickly and efficiently and preferably avoid the need to erect scaffolding within the furnace chamber.

Summary of the invention

According no a first aspect of the invention, there is provided a device for removing scale from the outer surface of a tube oomprising an annular collar formed of at least two parts so as to be capable of being assembled around the tube and carrying cleaning elements for scraping or impacting the outer surface of the tube as the collar is rotated about the axis of the tube, and a carriage operative to displace the collar parallel to the axis of the tube and carrying a motor for applying torque to cause the collar to rotate about the tube.

Tn an embodiment of the invention, the carriage is also formed of two parts so as to be capable of being assembled around the tube and includes rollers for engaging the outer surface of the rube being cleaned to centre the carriage on tho tubc.

Tt is possible for the carriage to be advanced along the length of the tube by means of a pulley system. In place of erecting scaffolding, it is only necessary to secure a pulley system to the upper end of the tube and then to use cables connected to the carriage tc raise and lower the device. There is no need in this case to use a motor as the device may be raised and lower manually.

It is alternatively possible for the carriage to be designed to be self-propelling along the length of the tube.

This may be achieved by means of wheels frictionally engaging the ourer surface of the tube or by relying on the principle used no climb trees and telegraph poles. In the latter case, the carriage may have two axially spaced bands capable of gripping and releasing the outer surface of the tube and a motor or hydraulic system for changing the axial distance between the two bands. In this way, at any one time the weight of the oarriage oan be supported by one band while the other is released and repositioned along the tube.

When torque is applied to rotate the collar, the carriage will experience a reaction torque in the opposite direction. To prevent the carriage from rotating, it is desirable to provide the carriage with a radially projecting abutment to conraot the surface of an adjacent heat exchanger tube.

Preferably, the abutment includes a roller to minimise resistance to movement of the carriage in a direction parallel to the axis of the tubes.

The collar may be provided with an adjuster to vary the radial force applied by the cleaning elements.

If dcoirod, a control may bo providod to allow tho adjuster to be set remotely by an cperator.

The carriage may additionally support a camera or an inspection tool to enable the operator to inspect the integrity of the tube and/or the cleaning efficiency. The operator may then adjust the force applied by the cleaning elements to optimise scale removal without damage the tube.

According cc a second aspect cf the invention, there is provided a method of removing scale from the outer surface of a tube, which comprises assembling around the tube an annular collar formed of at least two parts and carrying cleaning elemenrs for scraping or impacting the outer surface of the rube as the collar is rotated about the axis of the tube, securing to the tube a carriage carrying a motor for applying torque to cause the collar to rotate about the tube, and advancing the carriage and the collar along the length of the tube.

Brief description of the drawings

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows a collar formed into two semi-circular halves that can be assembled around a tube to be cleaned, Fig. 2 shows the collar of Fig. 1 in its closed position, Fig. 3 shows a first stage in assembling a cleaning device of the invention around a tube to be cleaned, and Fig. 4 shows the cleaning device after it has been fully assembled around the tube.

Detailed description of the illustrated embodiment

Fig. 1 shows a collar 10, formed of two semi-circular toothed halves ba and lOb that are pivoted to each other by a pin 12. After the two halves ba and lOb have been fitted around a tube to be cleaned, a second pin is inserted into holes 14 to form a complete annular toothed ring surrounding the tube.

Because the collar 10 is formed in two halves, access to a free end of the tube is not reguired for its installation around a tube.

The toothed ring oarries alternate posts around its circumference. Dosts 16 carry rotating wheels 18 that are used for guiding and positioning of the collar. The wheels 18 have spacers 20 that serve the centre the collar 10 on the tube being cleaned and their rims are designed to roll on a carriage, co be described below.

The other posts 22 carry cleaning elements that are designed to remove scale from the surface of the tube either by scraping or by chipping. Thus, the posts 22 may carry scraping blades or protruding pyramidal or hemispherical blocks. It will be seen from Fig. 2 that the posts 16 on the underside of the collar 10 are aligned with the posts 22 on the upper side.

It is possible for the pin 12 to be formed of two eccentric parts engaging in the respective halves of the collar 10. In this way, by rotating the pin 12, it is possible to vary the mean diameter of the collar and thereby control the aggressiveness of the cleaning elements.

To clean the surface of a tube, it is necessary to mount the collar 10 around the tube, then to rotate it and move it along the length of the tube. The latter tasks are porformod by a carriagc 30, shown in Fig. 3 which, likc thc collar 10, is formed in parts that can be assembled around the tube.

The carriage 30 comprises a lcwer platform 32 having radially spaced downwardly projecting arms bearing rollers 33 that contact the ouster surface of the tube 50 to be cleaned. These arms serve to centre the carriage 30 on the tube 50 and to slide along the tube freely. The platform has circumferentially spaced pillars 52 that allow a second similarly constructed platform 34 to be bolted to the platform 32 to form a cage for containing the collar 10 with the wheels 18 of the collar 10 rolling on the two platforms.

To allow quick assembly of the carriage, the upper platform 34 has holes to receive the ends of the pillars 52 and locking places 35 with keyhole slots are fitted over the protruding ends of the pillars 52 and rotated to engage the narrower regions of the keyhole slcts in grooves in the pillars 52.

An air motor 36, or other motorised drive, mounted in the carriage 30 is connected by a set of gears 37 to drive the collar 10 and cause it to rotate about the tube in order to remove scale from the tube 50. The carriage 30 also has a radial arm fitted with a roller 40 that rolls on a adjacent heat exchanger cube 52 to prevent the carriage from rotating about the tube on account of the tcrgue reaction.

By virtue of the collar 10 being trapped between the two platforms 32 and 34 of the carriage 30, its position along the length of the tube 50 is determined by the position of the carriage 30. To clean the entire length of the tube 50, it is therefore necessary to move the carriage along the tube.

Tn one embodiment, the carriage 30 is formed with an anchoring point for a support cable passing over a pulley mountod ncar thc top of tho tubo 50. Tho dovico comprising the carriage 30 and the collar 10 will tend to fall under its own weight no the lower end of the tube 50 and it can be raised by means of a manually or motor operated winch around A camera may be mounted on the carriage 30 to permit the cleaning operation to be monitored by the operator. The operator can modify the aggressiveness of the cleaning elements of the collar 10 by contrclling the clamping pressure of the collar 10 so top achieve efficient de-scaling without causing damage to the tube. The visual image can also indicared whether the speed of movement of the cleaning device along the tube needs to be increased or decreased, if the movement is continuous. As an alternative, the carriage 30 may be held stationary while one section is being cleaned and then advance incrementally by the operator once cleaning of one section of the tube 50 has been completed.

As an alternative to moving the carriage by a cable, the carriage may be designed to be self-propelling. Thus the carriage may include a second motor driving diabolo shaped wheels clamped io the outer surface of the tube SO. As & further option, the carriage may have two axially spaced bands capable of being selectively tightened around the girth of the tube 50. To advance the cleaning device, a first band is tightened while the second is released and repositioned relative to the carriage. Next, the second band is tightened while the first is being repositioned relative to the carriage.

As a further possibility, it is possible for the cleaning elements on the collar 10 to be designed to apply a force to move the cleaning device axially. For example, the cleaning elemencs may includes scrapers or cutter wheel that are inclined so as to trace a helical path around the tube and thoroby tond to ocrow tho collar along tho tubo. Tho bias to move along the tube can in this case be resisted by a brake. Thus, whenever the brake is released, the device will tend to move along the tube being cleaned and the brake may be used to set the rate of movement or to halt the device at regular intervals.

Claims

CLAIMS1. According to a first aspect of the invention, there is provided a device for removing scale from the outer surface of a tube comprising an annular collar formed of at least two parts so as to be capable of being assembled around the tube and carrying cleaning elements for scraping or impacting the outer surface of the tube as the collar is rotated about the axis of the tube, and a carriage operative to displace the collar parallel to the axis of the tube and carrying a motor for applying torque to cause the collar to rotate about the tube.
2. A device as claimed in claim 1, wherein the carriage is formed of two or more parts so as to be capable of being assembled around the tube and includes rollers for engaging the ourer surface of the tube being cleaned to contro tho carriago on tho tubo.
3. A device as claimed in claim 1 or 2, wherein a pulley system If provided to advance the carriage along the length of the tube.
4. A device as claimed in claim 1 or 2, wherein the carriage is self-propelling along the length of the tube.
5. A device as claimed in claim 4, wherein the carriage includes motor driven wheels for frictionally engaging the oucer surface of the tube.
6. A device as claimed in claim 4, wherein the carriage includes two axially spaced bands capable of gripping and releasing the outer surface of the tube and a motor or hydraulic system for changing the axial distance between the two bands.
7. A device as claimed in any preceding claim, wherein the carriage is provided with a radially projecting abutment arm to contact the surface of an adjacent heat exchanger tube.
8. A device as claimed in claim 7, wherein the abutment arm includes a roller, tc reduce resistance to movement of the carriage in a direction parallel to the axis of the tubes.
9. A device as claimed in any preceding claim, wherein the collar is be provided with an adjuster to vary the aggressiveness of the cleaning elements.
10. A device as claimed in claim 9, wherein a control is provided to allow the adjuster to be set remotely by an operator.
11. A device as claimed in any preceding claim, wherein the carriage additionally supports a camera to enable the operator to monitor the cleaning operation.
12. A method of removing scale from the outer surface of a tube, which comprises assembling around the tube an annular collar formed of at least two parts and carrying cleaning elements for scraping or impacting the outer surface of the rube as the collar is rotated about the axis of the tube, securing to the tube a carriage carrying a motor for applying torgue to cause the collar to rotate about the tube, and advancing the carriage and the collar along the length of the tube.
13. A device for cleaning a tube constructed and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.