Abstract:
A system and method for cleaning elongated tubes is presented. An apparatus for cleaning elongated tubes includes a cart, a lance, a pressure sensing device and a propulsion device. The lance sprays material into elongated tubes to clean the elongated tubes. The cart supports the lance while the cart is moves in a rail in a forward direction and in a reverse direction. The pressure sensing device is located in the cart detects a pressure exerted on the cart as the cart moves in a forward direction in the rail. The propulsion device, upon the pressure sensing device detecting a pressure crossing a threshold value, propels the cart in the reverse direction for predetermined distance or time before again propelling the first cart in the forward direction.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 12/917,925, filed Nov. 2, 2010; the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present invention relates generally to apparatus and methods for cleaning elongate tubes. More particularly, the apparatus and methods relate to using a lance to spray high pressure water into elongated tubes. Specifically, the apparatus and methods of the present invention relate to guiding a lance into elongated tubes by opening and closing doors supporting the lance. 
         [0004]    2. Background Information 
         [0005]    Heat exchangers are used for the transfer of heat from one fluid medium to another. One of the fluids passes through a series of conduits, or elongated tubes, while the other passes on the outside of the tubes. During this process, carbonaceous and other deposits form on the interior of the individual tubes. Debris and other dirt collects on the surface of the individual tubes. To maintain efficient operation, it is necessary to periodically remove the tubes and clean their interior and exterior surfaces. 
         [0006]    One method of cleaning the interior of heat exchanger tubes includes the progressive insertion of a small diameter tube, known as a lance, into the heat exchanger tube and the pumping of high pressure water through the lance to clean the interior of the tube. The water pressure in a lance may easily exceed 10,000 psi with flow rates in excess of 100 gallons per minute. There are problems inherent in using a lance to clean heat exchangers. For example, it is very difficult to keep the lance from buckling and bending while it is being guided into the tube. A more serious problem, however, is jet reaction from the high pressure stream. Since the fluid is forced through the lance at extremely high pressures (in excess of 10,000 psi) the fluid discharge from the lance tip can frequently blow backward and strike the operators guiding the lance. 
         [0007]    One apparatus used to clean heat exchangers supports the rear portion of the lance in an elongated channel member which has an open top. The front end (operating end) of each lance is fed into the tube through a vertical separator plate positioned at the front end of the channel member. The drive means comprises a set of motor-driven friction rollers which engage the lances immediately behind the separator plate. The major portion of the lance is supported in the open channel member behind the drive rollers and the motor. However, in these types of apparatus the lance can be quite long and hard to accurately position as it travels on the channel member. Therefore, improved heat exchanger cleaning technology is desired. 
       SUMMARY 
       [0008]    The preferred embodiment is an apparatus for cleaning elongated tubes. The apparatus includes a cart, a lance, and a pressure sensing device and a propulsion device. The lance sprays material into elongated tubes to clean the elongated tubes. The cart supports the lance while the cart is moves in a rail in a forward direction and in a reverse direction. The pressure sensing device is located in the cart and detects a pressure exerted on the cart as the cart moves in a forward direction in the rail. The propulsion device, upon the pressure sensing device detecting a pressure crossing a threshold value, propels the cart in the reverse direction for predetermined distance or time before again propelling the first cart in the forward direction. 
         [0009]    Another configuration of the preferred embodiment is a method of cleaning elongated tubes. A cart holding a lance is propelled through a rail in a forward direction. Material is sprayed out of the lance to clean an elongated tube. During this process a pressure may be applied to the cart and this pressure may cross a threshold value. In response to the pressure crossing the threshold, the cart stopped and backed up in backward direction for a distance. This distance may be a predetermined distance or the cart can back up for a time period. After backing the cart up the distance, the cart is again moved in the forward direction to continue cleaning the elongated tube. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    One or more preferred embodiments that illustrate the best mode(s) are set forth in the drawings and in the following description. The appended claims particularly and distinctly point out and set forth the invention. 
           [0011]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate various example methods, and other example embodiments of various aspects of the invention. It will be appreciated that the illustrated element boundaries (e.g., boxes, groups of boxes or other shapes) in the figures represent one example of the boundaries. One of ordinary skill in the art will appreciate that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of another element may be implemented as an external component and vice versa. Furthermore, elements may not be drawn to scale. 
           [0012]      FIG. 1  illustrates an example environment in which a preferred embodiment of an apparatus for cleaning elongated tubes operates. 
           [0013]      FIG. 2  illustrates an example side view of a motorized cart and a lance cart of the preferred embodiment. 
           [0014]      FIG. 3  illustrates an example top view of the motorized cart and the lance cart of the preferred embodiment. 
           [0015]      FIG. 4  illustrates an example front view of the lance cart of the preferred embodiment. 
           [0016]      FIG. 5  illustrates an example bottom view of the motorized cart and the lance cart of the preferred embodiment. 
           [0017]      FIG. 6  illustrates an example perspective view of a rail and two doors of the preferred embodiment. 
           [0018]      FIG. 7  illustrates an example front view of a door of the preferred embodiment in the closed position. 
           [0019]      FIG. 8  illustrates an example side view of a door of the preferred embodiment in the open position. 
           [0020]      FIG. 9  illustrates an example cross-sectional view of the door of the preferred embodiment taken at line  9  in  FIG. 8 . 
           [0021]      FIG. 10  illustrates an example internal side of a motorized cart and a lance cart of the preferred embodiment as viewed through the rail. 
           [0022]      FIG. 11  illustrates an example cross-sectional view of the motorized cart of the preferred embodiment taken at line  11  in  FIG. 10 . 
           [0023]      FIG. 12  illustrates an example cross-sectional view of the motorized cart of the preferred embodiment taken at line  12  in  FIG. 10 . 
           [0024]      FIG. 13  illustrates an example cross-sectional view of the motorized cart of the preferred embodiment taken at line  13  in  FIG. 10 . 
           [0025]      FIG. 14  illustrates an example side view of the lance cart of the preferred embodiment as it approaches a door. 
           [0026]      FIG. 15  illustrates an example top view of the lance cart of the preferred embodiment as it approaches the door. 
           [0027]      FIG. 16  illustrates an example top view of the lance cart of the preferred embodiment as it opens the door. 
           [0028]      FIG. 17  illustrates an example top view of the lance cart of the preferred embodiment as it passes through two doors in the open position. 
           [0029]      FIG. 18  illustrates an example side view of the lance cart of the preferred embodiment as it opens the door. 
           [0030]      FIG. 19  illustrates an example top view of the lance cart of the preferred embodiment as it travels in the reverse direction. 
           [0031]      FIG. 20  illustrates an example top view of the lance cart of the preferred embodiment as it closes a door while traveling in the reverse direction. 
           [0032]      FIG. 21  illustrates an example top view of the lance cart of the preferred embodiment after it has closed two doors while traveling in the reverse direction. 
           [0033]      FIG. 22  illustrates an example side view of the apparatus of the preferred embodiment showing the lance traveling in the forward direction while encounter heavy material in the tube. 
           [0034]      FIG. 23  illustrates an example side view of the apparatus of the preferred embodiment showing the lance traveling in the reverse direction after encountering heavy material in the tube. 
           [0035]      FIG. 24  illustrates an example side view of the apparatus of the preferred embodiment showing the lance traveling in the forward direction after traveling in the reverse direction after encountering heavy material in the tube. 
           [0036]      FIG. 25  illustrates an example side view of the lance cart of the preferred embodiment mounted with a dual lance. 
           [0037]      FIG. 26  illustrates an example front view of the lance cart of the preferred embodiment mounted with the dual lance. 
           [0038]      FIG. 27  illustrates configuration of the preferred embodiment as a method of cleaning elongated tubes. 
       
    
    
       [0039]    Similar numbers refer to similar parts throughout the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0040]      FIG. 1  illustrates a tube cleaning apparatus  1  resting on two support structures  2  while cleaning one of the tubes  4  of a heat exchanger  3 . Those of ordinary skill in the art will appreciate that the tube cleaning apparatus  1  can be mounted in a mechanical rack that is sturdy enough to support the apparatus  1  and to provide for the rapid repositioning of the apparatus  1  to other positions to clean other tubes  4  of the heat exchanger  3 . The tube cleaning apparatus  1  includes a rail  17  (e.g., channel) with a front end  6  and a back end  7 , and a tube cleaning cart system  19 . The tube cleaning cart system includes a motorized cart  20  and a lance cart  50  mounted with a lance  51 . The carts  20 ,  50  are made out of solid material such as a metal and are best seen in  FIGS. 2 ,  3  and  5 . The motorized cart  20  includes a left side wall  34 , right side wall  36 , front side wall  35  and a back side wall  37 . Similarly, the lance cart  50  includes a left side  64 , a right side  65  a front side  63  and a back side  62 . 
         [0041]      FIG. 1  also illustrates four door assemblies  13 ,  14 ,  15 ,  16  attached to the rail  17 . In the preferred embodiment, the door assemblies  13 ,  14 ,  15 ,  16  are equally spaced from each other and evenly distributed the length of the rail  17 . One of ordinary skill in the art will appreciate that  FIG. 1  illustrates four door assemblies  13 ,  14 ,  15 ,  16 ; however, fewer than four doors or more than four doors can be attached to the rail  17 . As discussed in detail below, the door assemblies  13 ,  14 ,  15 ,  16  support the lance  51  as it travels forward and backward in the rail  17 . Also as discussed in detail below, as the lance cart  50  approaches a door moving in the forward direction toward the back end  7  of the rail, the door is opened. When the lance cart  50  approaches a door moving in the reverse direction toward the front end  6  of the rail, the door is closed. 
         [0042]    A supply of high pressure water  10  and/or high pressure air  9  is connected to the motorized cart  20  and to the lance cart  50 .  FIG. 2  illustrates the water line connector  60  and the air line connector  61  on the lance cart  50 . The high pressure water and/or air can be used as a material that is ejected from a tip  52  of the lance  51  at high pressure as a spray  53  to clean unwanted materials from the tubes  4 . The water and/or pneumatic oil can also be used as an energy source to propel the two carts  20 ,  50  in the rail  17  so that the lance  51  can be inserted into the tubes  4  and removed from the tubes  4  of the heat exchanger  3 . Water may generally exit the lance tip  52  at 10,000 to 40,000 psi. The water may be connected to a controller  11  of the motorized cart  20 . The controller  11  can regulate the amount of air and/or pneumatic oil received at a cart motor  21  to regulate the speed that the motorized cart  31  that propels the lance cart  50 . 
         [0043]      FIG. 6  illustrates that in the preferred embodiment, a cross-section of the rail  17  is C-shaped with an open top  75  that allows the lance  51  to project out of the open top  75 . The rail  17  is a rectangle shape with a flat bottom wall  70 , a left side wall  71 , a right side  72  and a pair of upper lips  73  and  74  projecting inward from the tops of the sides  71 ,  72 . These walls form an inner channel chamber  78 . The left side wall  71  of the rail  17  has a gear rack  76  running generally the length of the rail  17 . As best shown in  FIG. 11 , this provides for a drive gear  22  in the motorized cart  20  to engaged the gear rack  76  and, thus, propel the motorized cart  20  and lance cart  50  across the rail  17 . An opening is  26  formed in the right side wall  36  of the motorized cart  20  and the drive gear  22  extends from this opening  26  to engage the gear rack  76 . 
         [0044]    As best seen in  FIG. 10 , a variety of wheels mounted on the motorized cart  20  and the lance cart  50  ensure the carts  20 ,  50  travel securely within the rail  17 . Lower motorized cart wheels  23  and lower lance cart wheels  54  travel along the bottom  70  of rail  17 . Upper motorized cart wheels  24  and upper lance cart wheels  55  travel along a bottom surface of the upper lips  73 ,  74 . Wall motorized cart wheels  25  mounted to the motorized cart  20  with angle bars  27 ,  32  travel along the inside surface of the right side  72 . Motorized cart lip wheels  28  and lance cart lip wheels  56  travel along inside edges of the upper lips  72 ,  73  of the rail  17 . The motorized cart  20  is held together by bolts  29  and the lance cart  50  is held together by bolts  59 . 
         [0045]    A motor  30  is mounted to the top of the motorized cart  20 . The motor  30  may be a hydraulic or pneumatic motor. A drive shaft  31  ( FIG. 2 ) connects the drive gear  22  with the motor  30 . A coupling  40  connected between the angle bar  32  on the motorized cart  20  and an angle bar  41  on the lance cart  50  connects the carts  20 ,  50  together. This connector  40  may be a pressure sensitive connector that monitors the pressure between the two carts and sends a pressure indicator to the controller  11  through a feedback line  42 . In other configurations, a pressure indication can be mechanically feedback directly to the motor  30  (or other motor regulator). 
         [0046]    The lance cart  50  includes a lance mounting bracket  66  ( FIG. 2 ) supporting a lance gear box  77 , a drive assembly  68 , and a lance coupling  69 . The lance gear box  77  is coupled to the drive assembly  68  with a drive belt so that this assembly is configured to mechanically spin the lance  51 . The lance coupling  69  is attached to a lance connector  67 . The lance connector  67  allows the lance  51  to be easily attached and removed from the lance cart  50 . The lance cart  50  also includes a top door pusher  80  and a bottom door pusher  81 . The pushers  80 ,  81  are made out of polyurethane material and are attached to a pusher mounting bracket  82 . The pusher mounting bracket  82  is mounted to the top of the lance mounting bracket  66  with one or more fasteners  83 . The bottom door pusher  81  is mounted to the bottom of the pusher mounting bracket  82  while the top door pusher  80  is mounted to the top of the pusher mounting bracket  82 . The pushers  80 ,  81  are fastened to the pusher mounting bracket  82  with one or more bolts  84  or other fasteners. The top door pusher  80  may be formed with beveled corners  86  at the two corners used to push close doors of the door assemblies  13 ,  14 ,  15 ,  16 . The bottom door pusher  81  may be formed with beveled corner at the two corners used to push open the doors of the door assemblies  13 ,  14 ,  15 ,  16 . 
         [0047]    In the preferred embodiment, the door assemblies  13 ,  14 ,  15 ,  16  are placed on alternating sides of the rail  17 . For example, door assemblies  13  and  15  can be placed on the of right side wall  72  the rail  17  as shown in  FIG. 1  and door assemblies  14  and  16  can be placed on the left side wall  71 . Each door assembly  13 ,  14 ,  15 ,  16  includes a door base  89  and a door  12 . This is best seen in  FIGS. 7-8  that illustrate door assembly  14 . The door base  89  is comprised of mounting blocks  92 ,  92  attached to a base  90 . The door  12  is pivotally mounted with a pivot rod  85  to the door base  89 . The pivot rod  85  is passes through the mounting blocks  91 ,  92 . The base  90  is connected to the rail  17  with one or more fasteners  93  that can be bolts. A stop block  94  with a first leg  120  and a second leg  122  ( FIG. 9 ) is also attached to the pivot rod  85  between the mounting blocks  91 ,  92 . 
         [0048]    The door  12  includes a lance support  100  that is sandwiched between two lance brackets  101 . The lance support  100  is a generally rectangular shaped polymer block with a tapered opening  103  cut out from one sided of the block. The tapered opening  130  further includes a lance support opening where a lance  51  is supported when the door  12  is in the closed position. In operation the tapered opening  103  supports the lance  51  until the door  14  is pushed open by the lance cart  50 . The lance brackets  101  are fastened together with fasteners  102  so that the lance support  100  is rigidly attached to the pivot rod. A pusher tab block  104  with a first surface  105  and a second surface  106  is attached to the top of the lance brackets  101 . 
         [0049]    As seen in  FIG. 9 , two first magnets  95  are located adjacent one surface of the stop block  94 . Two different second magnets  96  are located adjacent a second surface of the stop block  94 . A filler nut  99  can be inserted opposite the magnets  95 ,  96 . Firsts metal pegs  97  are attached at a first location on the rail  17  and second metal pegs  98  are attached at a second location on the rail  17 . The metal pegs  97 ,  98  are formed with a metal that the magnets  95 ,  96  are attracted to. When the door  14  of  FIG. 6  is in the “closed position” the lance support  100  spans across the upper open portion of the rail  17  and the second magnets  96  are adjacent the second metal pegs  98 . When the door  14  of  FIG. 6  is in the “open position” the lance support  100  is generally parallel to the left side  72  of the rail  17  and the first magnets  95  are adjacent the first metal pegs  97 . The stop block  94  is formed so that the lance support  100  cannot be rotated beyond 90 degrees between the open position and the closed position. The attractive force of the magnets  95 ,  96  and the metal pegs  97 ,  98  holds the door  14  in one of the corresponding positions until sufficient force is applied to the door  14  to rotate it toward the other position. Alternative to the metal pegs  97 ,  98  magnets with a polarity that attracts them to magnets  95 ,  96  can be used in place of the metal pegs  97 ,  98 . 
         [0050]    At the start of an elongated tube  4  cleaning operation, the motorized cart  20  and the lance cart  50  are located near the back side  7  of the rail  17  with both carts  20 ,  50  between the back side  7  and the first door  13 . All the doors  12  are in the closed position. The cleaning operation is started when air and/or water are feed to the motor  30  and the lance cart  50 . The motor  30  will drive the drive gear  22  which will rotate while engaged with the gear rack  76  to propel the two carts  20 ,  50  toward the front end  6  of the rail  71  and the so the lance  51  is inserted into the heat exchanger  3  and high pressure water exiting the lance tip  52  can begin cleaning one of the elongated tubes  4 . The lance gear box  77  will rotationally spin the lance  51 . This spinning assist in stabilizing the lance  51  as it ejects high pressured water. 
         [0051]    As the lance cart  50  progresses toward the front  6  of the rail  17  in the direction of arrow A it will reach the first door assembly  13  as shown in  FIG. 15 . As shown in  FIGS. 14 and 15 , the lance coupling  67  will make contact with the door  12  of door assembly  13  and begin pushing the door  12  open. As the door continues to open, eventually a beveled surface  87  of the bottom door pusher  81  will make contact with the door  12  to continue to push the door  12  open. This contact will eventually cause the magnetic attraction between the second magnets  96  and the second metal pegs  98  to be overcome and the door will begin to rotate in the direction of arrow B from the closed position toward the open position. As the door  12  is rotated open, eventually the first magnets  95  form an attractive force with the first metal pegs  97  to snap the door  12  of door assembly into the open position and to hold the door  12  in this position.  FIG. 17  shows the lance cart  50  as it is passing the second door  14  with both doors assemblies  13 ,  14  in the open position. Notice that the second door assembly  14  on the opposite of the rail  17  than first door assembly  13  so that its door  12  will rotate in the direction of arrow C which is the opposite of arrow B. The bottom door pusher  81  continues to open doors in this manner until the lance  51  has been inserted sufficiently far into the elongated tube  4 . 
         [0052]    After the lance  51  has been inserted sufficiently far into the elongated tube  4 , the motor  30  will reverse direction and the two carts  20 ,  50  will begin to travel in the direction of Arrow D toward the back end  7  of the rail  17  as the lance  51  is withdrawn from the tube  4 . As the lance cart  50  reaches the door  12  of door assembly  16  as shown in  FIGS. 18 and 19 , one of the beveled corners  87  of the top door pusher  80  will make contact with the second surface  106  of the pusher tab block  104 . This contact will cause the magnetic attraction between the first magnets  95  and the first metal pegs  97  to be overcome and the door  12  of door assembly  16  will begin to rotate in the direction of arrow E ( FIG. 20 ) from the open position toward the closed position. As the door  12  is rotated closed, eventually the second magnets  96  form an attractive force with the second metal pegs  98  to snap the door  12  of door assembly  16  into the closed position and continue to hold the door  13  in this position.  FIG. 21  shows the lance cart  50  as it is passing door assembly  15  with both door assemblies  15 ,  16  in the closed position. The top door pusher  80  continues to close doors in this manner until the lance  51  has been sufficiently removed from the elongated tube  4 . 
         [0053]    In operation, as the lance cart  50  travels in a forward direction as shown by arrow S in  FIG. 22  the lance may encounter enough dirt or grime built up inside the tube  4  that is difficult to blast out of the tube  4  by the lance  51 , the pressure in the coupling  40  will cross a threshold level. When this happens, the controller  11  can cause the motorized cart  20  to run in the reverse direction as shown by arrow T in  FIG. 23 . Traveling in the reverse direction least partially pulls the lance  51  away from the heat exchanger  3 . After the lance  51  is partial removed, the controller  11  can then signal for the motor  30  to run in the forward direction as shown by arrow U in  FIG. 24  to begin re-inserting the lance  51  back into the heat exchanger  3 . These actions can increase the chances of the apparatus  1  removing unwanted material that is tightly attached to the heat exchanger  3 . 
         [0054]    In another configuration of the preferred embodiment, lance cart  50  of the apparatus  1  is mounted with a dual lance  100  as shown in  FIGS. 25 and 26 . The dual lance  100  contains a first lance  101  and a second lance  102 . The dual lance connectors  114 , gear box  113 , drive assembly  68 , and some other components of the single lance cart  50  may need to be modified and/or duplicated in the dual lance configuration. The dual lance is support on a dual lance cart  115  that is similar to the single lance cart  50 . In operation, the first lance  101  can be inserted into a first tube  4  and the second lance  102  can be inserted into a second tube  4  to clean two tubes  4  at the same time. In one configuration of the preferred embodiment, the distance between the first lance  101  and the second lance  102  is adjustable so that tubes  4  with different diameters can be cleaned. Of course, in other configurations more than two lances can be mounted onto the lance cart  50 . 
         [0055]    While the present invention has been described in connection with the preferred embodiments of the various figures, it is to be understood that other similar embodiments may be used or modifications and additions may be made to the described embodiment for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims. 
         [0056]    Example methods may be better appreciated with reference to flow diagrams. While for purposes of simplicity of explanation, the illustrated methodologies are shown and described as a series of blocks, it is to be appreciated that the methodologies are not limited by the order of the blocks, as some blocks can occur in different orders and/or concurrently with other blocks from that shown and described. Moreover, less than all the illustrated blocks may be required to implement an example methodology. Blocks may be combined or separated into multiple components. Furthermore, additional and/or alternative methodologies can employ additional, not illustrated blocks. 
         [0057]      FIG. 28  illustrates a configuration of the preferred embodiment as a method  500  of cleaning elongated tubes such as the tubes in a heat exchanger. The method  500  begins by moving a cart, at  502 , in a channel in a forward direction. The cart mounted with a lance sprays water or other material, at  504 , at high pressure to clean grime and other unwanted material from the elongated tubes. The water is sprayed from the lance as the cart moves in the channel. 
         [0058]    A first door is moved from a first closed position to a first open position, at  506 , as the cart approaches the first door. A second door is moved from a second closed position to a second open position, at  508 , as the cart approaches the second door. The second door is moved to the second open position after the first door is moved to the first open position. 
         [0059]    When removing the lance from the tube, the cart is moved in the channel in a reverse direction. The second door is moved from the second open position to the second closed position as the cart approaches the second door in the reverse direction. The first door from the first open position to the second closed position as the cart approaches the first door in the reverse direction. The first door is moved to the first closed position after the second door is moved to the second closed position. 
         [0060]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. Therefore, the invention is not limited to the specific details, the representative embodiments, and illustrative examples shown and described. Thus, this application is intended to embrace alterations, modifications, and variations that fall within the scope of the appended claims. 
         [0061]    Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described. References to “the preferred embodiment”, “an embodiment”, “one example”, “an example”, and so on, indicate that the embodiment(s) or example(s) so described may include a particular feature, structure, characteristic, property, element, or limitation, but that not every embodiment or example necessarily includes that particular feature, structure, characteristic, property, element or limitation. Furthermore, repeated use of the phrase “in the preferred embodiment” does not necessarily refer to the same embodiment, though it may.