BACKGROUND OF THE DISCLOSURE

The present disclosure is directed to high pressure waterblasting lance positioning systems. Embodiments of the present disclosure are directed to an apparatus and a system for aligning one or more flexible tube cleaning lances in registry with tube openings through a heat exchanger tube sheet.

One auto-indexing system is described in US Patent Publication No. 20170307312 by Wall et. al. This system includes optical scanning, cleaning and inspecting tubes of a tube bundle in a heat exchanger. It involves use of a laser or LED optical scanner for scanning the surface of the tube sheet to locate the holes or locate holes from a predetermined map. Once the hole location is determined, the cleaner is positioned over the hole and the tube cleaned.

Another apparatus for a tube sheet indexer is disclosed in US Patent Publication 20170356702. This indexer utilizes a pre-learned hole pattern to identify location of subsequent holes once a particular hole location is sensed. This is because tube sheet hole penetrations are typically spaced apart at known locations from each other in either or both an x direction or y location. However, in some circumstances a hole location may be plugged or capped. Hence not always are the hole locations accurate or precise for accurate positioning of a flexible lance drive. Furthermore, an interference sensor must be used in addition to displacement sensors in order to ascertain accurate hole locations.

In some cases a camera may be utilized to optically learn and map the tube sheet faceplate arrangement in advance. However, such optical sensors require an unobstructed view of the tube sheet face and therefore cannot be utilized while the apparatus is in use. Further, optical sensors are very sensitive to light and shadows which can significantly affect the reliability of such scanning in adverse lighting conditions. The tube sheet face may also be caked with built up carbon, bitumen or other materials and therefore must be cleansed of such substances prior to use of optical sensors. Hence the tube sheet must first be cleaned of debris and the mapping must be done prior to tube cleaning operations. What is needed, therefore, is a system that can accurately sense and position a flexible lance drive apparatus in registry with each of a plurality of unplugged tube sheet holes without need of camera or an optical sensor for hole location and without resort to referencing to a predetermined map.

Conventional high pressure waterblasting equipment and systems also require an operator to activate high pressure fluid dump valves to divert high pressure fluid safely in the event of an equipment malfunction. Such systems often include a “deadman” switch or foot operated lever that must be actuated to stop the high pressure pump and/or dump/divert high pressure fluid to atmosphere or to a suitable container. These switches typically must be continuously depressed or held in order to permit high pressure fluid to be directed through the lance hose to the object being cleaned. When an event occurs requiring diversion or dump of high pressure fluid, it may take a second or two for the operator to react and release such a switch. Furthermore, it takes a finite amount of time for high pressure fluid pressure to decrease to atmospheric pressure. During such reaction and decay time, the high pressure fluid may still cause damage in the event of an unexpected malfunction. Therefore, there is a need for a smart system that can sense such events and dump or divert high pressure fluid pressure quickly in order to reduce these delays as much as possible.

SUMMARY OF THE DISCLOSURE

The present disclosure directly addresses such needs. The embodiments described herein may be utilized with rigid (fixed) lances or flexible lances and lance hoses. One embodiment of a lance indexing drive positioning system in accordance with the present disclosure utilizes an AC (alternating current) pulse inductive coupling sensor array mounted at a distal end of a flexible lance guide tube fastened to the lance tractor drive apparatus. This type of inductive sensor is insensitive to fouling, dirt, or other debris or detritus that may be present on a heat exchanger tube sheet face, thus eliminating the need for preliminary cleaning of the heat exchanger tube sheet prior to installation of the system.

When the lance tractor drive is mounted on a lance positioner frame fastened to a heat exchanger tube sheet face, for example, the lance guide tube or tubes are aligned perpendicular to the plane of the tube sheet face. The distal end(s) of the guide tube(s) are spaced from the tube sheet face by a gap, which is preferably less than an inch, to minimize the range of unconfined water spray during cleaning operations.

The pulse induction sensor array is configured with a single transmit coil placed at the distal end of one or more of the lance guide tubes and a plurality of receive coils arranged around and within the vicinity of each transmit coil. An AC pulse through the transmit coil generates an AC magnetic field that, when it collapses, causes eddy currents to be formed in any conductive material in the volume of the produced magnetic field. These eddy currents cause a magnetic field of a reverse polarity to be generated which creates a voltage differential in the receive coils. The transmit coils are larger than the receive coils so as to create eddy currents in poorly conductive materials in a volume that is proportional to the size of the guide tube to which the transmit coil is mounted. The receive coils are much smaller in diameter and are spaced around the periphery of the transmit coil. In an exemplary embodiment of the present disclosure the transmit coil is positioned on and around the distal end of the guide tube and hence adjacent the gap between the guide tube and the face of the tube sheet. The receive coils are spaced apart and positioned to form a ring of coils around the distal end of the guide tube. The eddy currents sensed by the receive coils are amplified and processed in a comparator in order to detect the presence or absence of metallic material adjacent the receive coils hence the signal is used to determine tube location.

Embodiments of the system in accordance with the present disclosure also sense and track position of a flexible lance hose being fed through the lance tractor drive apparatus. In one exemplary embodiment, hose position encoders/sensors are located in the inlet hose stop block fastened to the hose inlet of the lance tractor drive apparatus. The position sensors may be wheels that engage the lance hose as it is fed through the tractor drive apparatus. Each wheel rotation causes a signal to be sent to a controller indicative of the distance traveled by the hose during that wheel rotation. Another set of encoders also sense hose stop clips or clamps, also known as “footballs”, which are fastened to the high pressure lance hose, that signal the desired end of lance hose travel.

Such a lance tractor drive apparatus as described herein is essentially a smart tractor that, as part of the overall system, can provide a number of pieces of information to a data collection processor for subsequent analysis and utilization. For example one embodiment of a lance tractor drive apparatus described herein and its controller can provide current status, track machine operational status, as well as current status of the tubes being cleaned and can be used to predict status of each and every tube being cleaned. This data can be utilized to determine long term conditions of a heat exchanger, frequency of cleaning operations needed to optimize operation, and provide different job statistics that can be utilized to improve efficiencies, etc.

An exemplary embodiment in accordance with the present disclosure may alternatively be viewed as including a flexible high pressure fluid cleaning lance drive apparatus that includes a housing, at least one drive motor having a drive axle in the housing carrying a cylindrical spline drive roller, and a plurality of cylindrical guide rollers on fixed axles aligned parallel to the spline drive roller. A side surface of each guide roller and the at least one spline drive roller is tangent to a common plane between the rollers. An endless belt is wrapped around the at least one spline drive roller and the guide rollers. The belt has a transverse splined inner surface having splines shaped complementary to splines on the spline drive roller.

The drive apparatus further has a bias member supporting a plurality of follower rollers each aligned above one of the at least one spline drive roller and guide rollers, wherein the bias member is operable to press each follower roller toward one of the spline drive rollers and guide rollers to frictionally grip a flexible lance hose when sandwiched between the follower rollers and the endless belt. The apparatus includes a first sensor coupled to the drive roller for sensing position of the endless belt, a second sensor coupled to a first one of the follower rollers for sensing position of the first follower roller relative to a first flexible lance hose sandwiched between the first follower roller and the endless belt, and at least a first comparator coupled to the first and second sensors operable to determine a first mismatch between the first follower roller position and the endless belt position.

This embodiment of an apparatus in accordance with the present disclosure preferably further includes a third sensor coupled to a second one of the follower rollers for sensing position of the second one of the follower rollers relative to a second flexible lance hose sandwiched between the second one of the follower rollers and the endless belt. The exemplary apparatus also may include a second comparator operable to compare the second follower roller position to the endless belt position and determine a second mismatch between the second follower roller position and the endless belt position.

Preferably a controller is coupled to the first comparator and the second comparator operable to initiate an autostroke sequence of operations upon the first mismatch and second mismatch differing by a predetermined threshold. A fourth sensor may be coupled to a third one of the follower rollers for sensing position of the third one of the follower rollers relative to a third flexible lance hose sandwiched between the third one of the follower rollers and the endless belt. Also, a third comparator may be provided operable to compare the third follower roller position to the endless belt position and determine a third mismatch between the third follower roller position and the endless belt position. The controller is preferably coupled to the first comparator, the second comparator and the third comparator and is operable to initiate an autostroke sequence of operations upon any one of the first, second and third mismatches exceeding a predetermined threshold. Furthermore, the controller is preferably operable to modify clamping force if more than one of the first, second and third mismatches exceed a different predetermined threshold. The sensors utilized herein may be magnetic or Hall effect sensors and preferably include quadrature encoder sensors.

A flexible high pressure fluid cleaning lance drive apparatus in accordance with the present disclosure may comprise a housing, at least one drive motor having a drive axle in the housing carrying a cylindrical spline drive roller, a plurality of cylindrical guide rollers on fixed axles aligned parallel to the spline drive roller, and wherein a side surface of each guide roller and the at least one spline drive roller is tangent to a common plane between the rollers, an endless belt wrapped around the at least one spline drive roller and the guide rollers, the belt having a transverse splined inner surface having splines shaped complementary to splines on the spline drive roller, a bias member supporting a plurality of follower rollers each aligned above one of the at least one spline drive roller and guide rollers, wherein the bias member is operable to press each follower roller toward one of the spline drive rollers and guide rollers to frictionally grip a flexible lance hose when sandwiched between the follower rollers and the endless belt.

The apparatus includes a first sensor coupled to the drive roller for sensing endless belt position and a plurality of second sensors each coupled to one of the plurality of follower rollers each for sensing position of the one of the follower rollers relative to a flexible lance hose sandwiched between the one of the follower rollers and the endless belt. The apparatus preferably includes a first comparator coupled to the first sensor and each second sensor operable to determine a mismatch between each follower roller position and the endless belt position. The apparatus may further include a second comparator operable to compare each of the plurality of flexible lance hose positions with each other to determine another mismatch therebetween and a controller coupled to the second comparator operable to initiate an autostroke sequence of operations upon the another mismatch exceeding a predetermined threshold.

An apparatus in accordance with the present disclosure may alternatively be viewed as including a housing, at least one drive motor having a drive axle in the housing carrying a cylindrical drive roller, a plurality of cylindrical guide rollers on fixed axles aligned parallel to the drive roller, and wherein a side surface of each guide roller and the at least one drive roller is tangent to a common plane between the rollers, an endless belt wrapped around the at least one drive roller and the guide rollers, a bias member supporting a plurality of follower rollers each aligned above one of the at least one drive roller and guide rollers, wherein the bias member is operable to press each follower roller toward one of the drive rollers and guide rollers to frictionally grip a flexible lance hose when sandwiched between the follower rollers and the endless belt, a first sensor such as a magnetic quadrature encoder sensor coupled to the drive roller for sensing endless belt position, a plurality of second sensors such as magnetic quadrature encoder sensors each coupled to one of the plurality of follower rollers each for sensing position of the one of the follower rollers relative to a flexible lance hose sandwiched between the one of the follower rollers and the endless belt, a first comparator coupled to the first sensor and each second sensor operable to determine a mismatch between each follower roller position and the endless belt position, and a second comparator coupled to each of the second sensors operable to determine a mismatch between any two of the follower roller positions. The apparatus may also preferably include a controller coupled to the second comparator operable to initiate an autostroke sequence of operations upon the mismatch exceeding a predetermined threshold and may further include the controller being operable to initiate a change of clamp force or pressure if the mismatch between the follower roller positions and the belt position all or at least more than one, exceed a predetermined threshold.

An apparatus for cleaning tubes in a heat exchanger in accordance with the present disclosure may alternatively be viewed as including a lance positioner frame configured to be fastened to a heat exchanger tube sheet and a flexible lance drive fastenable to the frame configured for guiding a flexible cleaning lance from the lance drive into a tube penetrating through the tube sheet. The lance drive preferably has a follower roller riding on the flexible cleaning lance. This follower roller includes a sensor, such as a magnetic quadrature encoder that operates to provide roller position and direction of movement information for the flexible cleaning lance. The apparatus also includes a control box communicating with motors on the positioner frame and motors in the lance drive for controlling operation of the lance drive, a tumble box for converting air pressure to electrical power and for manipulating valves including a dump valve preferably contained within the tumble box for maintaining cleaning fluid pressure to the flexible cleaning lance when energized, wherein the electrical power is provided to components within the control box, the dump valve and the flexible lance drive, and a controller coupled to the follower roller sensor for sensing flexible lance position and sensing a reversal of flexible lance movement direction. This controller is operable to send a signal to the tumble box to actuate the dump valve to divert fluid pressure to atmosphere upon sensing the reversal of flexible lance hose direction.

Further features, advantages and characteristics of the embodiments of this disclosure will be apparent from reading the following detailed description when taken in conjunction with the drawing figures.

