Patent Publication Number: US-2017363285-A1

Title: Mounting Arrangement for Turbulators of a Furnace Heat Exchanger

Description:
FIELD OF THE INVENTION 
     The present invention relates to heat exchangers, and more particularly to an arrangement for mounting turbulators of a heat exchanger. 
     BACKGROUND 
     Boilers commonly consist of a boiler housing, a combustion chamber, a water jacket for receiving the liquid to be heated, a flue for discharge of the combustion products and a series of tubes arranged to pass through the water jacket, thereby connecting the combustion chamber and the flue. Thus, heated gases produced in the combustion chamber flow up the tubes to the flue. While the heated gases pass along the tubes, heat from the gases is transferred to the liquid in the water jacket. Furthermore, the efficiency of heat transfer may be increased by creating turbulence in the flow of the heated gases by, for example, placing flights or spirals within the tubes which are sometimes referred to in industry as ‘turbulators.’ However, soot and other debris from the heated gases will deposit along the inner surface of the tubes as well as on the flights and spirals. This in turn greatly decreases the efficiency of heat transfer, resulting in higher fuel costs. Eventually, the boiler must be shut down and each of the heat exchanger tubes cleaned individually, a difficult and time-consuming process due to the presence of the flights and/or spirals inserted within the tubes. 
     Systems have been developed to provide a means for quickly and easily cleaning heat exchanger tubes. These systems typically operate by longitudinal sliding movement of the respective flight in its tube by which contact of the flight with an inner surface of the tube is generated in order to remove deposited material from the inner tube surface. For example, the respective turbulator may generate a scraping action against the inner tube surface or may collide therewith during its longitudinal movement in a manner knocking off the deposited material as the turbulator is displaced vertically. 
     In spite of the availability of such a cleaning system, the turbulators must still be periodically removed from within the heat exchanger tubes for cleaning of the turbulators as well as to provide unobstructed access for periodic cleaning the inner surface of the respective tube, for example brushing of the tubes on an annual basis. Conventional arrangements that provide the tube cleaning operation described in the previous paragraph commonly require disassembly of the entire tube cleaning system in order to clean any one of the turbulators which typically must be removed from the tubes therefor. This increases time needed for cleaning of the turbulators. For example, the entire assembly may have to be lifted vertically out of the tubes or several turbulators at once removed from the tubes which may be cumbersome. Furthermore, in this type of arrangement several if not all of the turbulators must be simultaneously lowered back into the tubes which requires aligning multiple turbulators with the corresponding tubes. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the invention there is provided a boiler apparatus comprising: 
     a boiler housing; 
     a combustion chamber in the boiler housing for generating heated gases including combustion products; 
     a flue connected to the boiler housing for discharge of the combustion products; 
     a container in the boiler housing for receiving a liquid material to be heated; 
     a plurality of vertical tubes passing through the container and extending from the combustion chamber to the flue for receiving the heated gases and communicating heat from the heated gases to the liquid material, said tubes each having an inner surface over which the heated gases and combustion products pass and an outer surface in communication with the liquid material; 
     each tube having therein a helical turbulator arranged to create turbulence in the flow of the heated gases, thereby increasing heat transfer from the heated gases to the inner surface of the tube; 
     the turbulator comprising a strip with outer edges thereof defining outside turbulator edges and following a helical path about a central axis along the respective tube such that at least one of the outer edges is arranged in its helical path generally at the inner surface of the tube so as to be arranged for contact with the inner surface of the tube; 
     the tubes being arranged each to one side of the next so as to generally form a row; 
     the plurality of turbulators being mounted with a pivotal connection to a common shaft extending parallel to the row of the tubes; 
     the shaft being pivotally movable about its axis so as to effect through the pivotal connection of each turbulator a longitudinal vertical sliding movement of each of the turbulators relative to the respective tube from an operating position to a raised position and back to the operating position, the contact of said at least one of the outside turbulator edges and the movement thereof effecting a cleaning of the inner surface to remove combustion products deposited on the inner surface by the heated gases; 
     the pivotal connection of the respective turbulator including a bracket forming a channel with an open side receiving the shaft therethrough and an ear supported on the bracket opposite the open side wherefrom the turbulator pivotally depends downwardly; 
     the bracket being attached to the shaft by a removable pin passing through apertures in the bracket and the shaft so as to hold the bracket of the respective turbulator in fixed relation to the shaft; 
     whereby each turbulator is removably attached to the common shaft independently of the other turbulators. 
     For example, in one arrangement the bracket is generally C-shaped so as to generally follow part of a circumferential transverse periphery of the shaft. 
     Typically the turbulator is arranged depending downwardly from a location radially of the axis of the shaft such that the ear extends outwardly from the shaft in a generally radial direction relative thereto. 
     The removable pin comprises an elongate pin portion extending generally diametrically through the shaft through said cooperating apertures and a clip portion following an arcuate curving path about a circumferential periphery of the shaft from one end of the pin portion where the clip portion is pivotally connected to the pin portion to an opposite end of the pin portion where a terminus of the clip portion is matingly securable to the pin portion externally of the shaft. 
     Typically the pin portion where it passes through the bracket and shaft has a smooth cylindrical surface. 
     Thus typically the pin is not threadably mated with the bracket nor the shaft at the respective apertures so that a time required for installing or removing a selected one of the turbulators is expedited. 
     Typically the clip portion of the pin follows the arcuate curving path about a portion of the circumferential periphery of the shaft that is opposite the ear from which the turbulator depends. 
     Preferably the turbulators are at spaced positions along the shaft each longitudinally of the next. 
     Preferably the turbulators are disposed in an alternating arrangement relative to the shaft such that the turbulators are staggered relative to one another about the axis of the shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One embodiment of the invention will now be described in conjunction with the accompanying drawings in which: 
         FIG. 1  is a front elevational view of boiler apparatus according to the present invention. 
         FIG. 2  is a cross-sectional view along line  2 - 2  in  FIG. 1 . 
         FIG. 3  is a top plan view of the boiler apparatus of  FIG. 1  with a portion cutaway to show a heat exchanger of the boiler apparatus. 
         FIG. 4  is an enlarged sectional view of a portion of the boiler apparatus, similar to how it is illustrated in  FIG. 2 , with some components cutaway and some components omitted showing a tube cleaning system of the boiler apparatus. 
         FIG. 5  is a perspective view of the tube cleaning system. 
     
    
    
     In the drawings like characters of reference indicate corresponding parts in the different figures. 
     DETAILED DESCRIPTION 
     There is illustrated in the accompanying figures a boiler apparatus generally indicated at  10 . Generally speaking, the boiler apparatus  10  is a conventional such apparatus in which combustible material is burned, thereby generating heated gases and combustion products which pass through tubes  13  and out a flue  15  wherefrom they are discharged from the apparatus. Heat is extracted from the heated gases and combustion products in a conventional heat exchanger  18  of the boiler apparatus that is formed by the tubes  13  and a conventional container  20  through which the tubes pass. That is, as the heated gases and combustion products pass through the tubes  13  from a furnace  22  of the apparatus  10  to the flue  15 , the heat therein is transferred through a wall  24  of the respective tube to a liquid shown schematically at  25  that is contained in the container  20 . The container  20  is sometimes referred to in industry as a water jacket. The liquid  25  is then circulated to another location (not shown) externally of the boiler apparatus  10  for applying the heat thereto, for example a space to be heated or a consumable water supply. 
     More specifically, the boiler apparatus  10  comprises a housing  27  substantially enclosing components of the apparatus  10  as will be better appreciated hereinafter. The housing includes side walls  29 A- 29 D, a top wall  30 , and a base  31 . 
     Within the housing  27  there is defined a combustion chamber  34  where combustion of the combustible material, for example wood, occurs so as to generate the heated gases and combustion products which are by-products of the combustion process. The combustion chamber  34  is partitioned into upper and lower chambers  34 A and  34 B by a horizontal dividing wall  36  spanning from a front of the combustion chamber at the front housing wall  29 A to a rear of the combustion chamber defined by an interior wall within the housing  27 . 
     It is in the upper chamber  34 A where the combustible material is inserted, typically through an upper one 38 of a plurality of access doors  38 ,  39  in the front side wall  29 A of the boiler housing  27  used primarily for this purpose. A lower one of the access doors  39  sized smaller than the door  38  and which is adjacent the horizontal dividing wall  36  is usable for readily lighting the combustible material at its base. 
     Thus, initial burn of the combustible material occurs in the upper chamber  34 A in order to generate the heated gases and combustion products. These gases and combustion products then flow downwardly from the upper chamber to the lower chamber  34 B through, for example, holes in the horizontal dividing wall  36  that form passageways therefor. 
     In the lower chamber  34 B, which forms the furnace  22  of the apparatus, a majority of that which is received from the upper chamber is consumed in a secondary burn so as to extract additional heat therefrom, thereby raising the gases flowing through to the tubes to a highest temperature within the combustion process occurring in the boiler apparatus. The lower chamber  34 B is sized larger than the upper chamber in terms of depth between the front side wall  29 B and the rear side wall  29 B of the housing so as to extend from underneath the upper chamber  34 A to beneath the tubes  13 , which together with the container  20  are located in the housing  27  rearwardly of the upper chamber  34 A. 
     A plurality of the tubes  13  pass through the container  20  and extend vertically from the lower combustion chamber  34 B to the flue  15 , which is connected to the housing  27  at the top wall  30 . The tubes are thus arranged for receiving the heated gases and communicating heat from the heated gases to the liquid material. As such, each tube has an inner surface  24 A over which the heated gases and combustion products pass and an outer surface  24 B in communication with the liquid material  25  in the container  20 . 
     Within each tube  13  there is provided a helical turbulator  42  which is arranged to create turbulence in the flow of the heated gases, thereby increasing heat transfer from the heated gases to the inner surface  24 A of the tube as known in the art. 
     Each turbulator  42  of the illustrated arrangement comprises a strip of substantially rigid yet resilient material  44  with outer edges  45 A,  45 B thereof arranged to follow a helical path longitudinally of the respective tube such that at least one of the outer edges  45  is arranged in its helical path at the inner surface  24 A of the tube. That is, the helical path winds about a central axis coaxially along the respective tube and has a radius substantially equal to an inner diameter of the tube. For example, as in the illustrated arrangement the strip of the material is arranged in a helix where both outer edges  45 A,  45 B following parallel side-by-side paths but where only one of the outer edges  45 A is at the inner tube surface  24 A. In an alternative arrangement (not shown), the strip of the material may extend across the tube and may be helically twisted such that the outer edges follow paths substantially symmetrical relative to the central axis so as to be opposite one another and where both outer edges of the strip are arranged at the inner tube surface. 
     It will be appreciated that the outer edges  45 A,  45 B of the strip  44  define outside turbulator edges of the respective turbulator, and thus, as described in the previous paragraph, the respective outside turbulator edge which is at the inner tube surface  24 A is arranged for contact therewith in a sufficiently close fit of the turbulator and respective outside turbulator edge with the inner tube surface such that that outside turbulator edge in longitudinally vertical sliding movement of the turbulator can effect a cleaning action of the inner surface to remove deposits of the combustion products on the inner tube surface which otherwise reduce the efficiency of the heat transfer. In the illustrated arrangement there is provided a minute clearance gap between the inner tube surface  24 A and the respective outside turbulator edge  45 A thereat such that the turbulator may move transversely of the central tube axis in a vibratory manner as the turbulator is slidingly displaced along the tube. As such, the outside turbulator edge  45 A at the inner tube surface  24 A collides therewith in a manner knocking off the products deposited by the heated gases. In an alternative arrangement, the outside turbulator edge(s) at the inner tube surface  24 A may define a sliding fit with the inner surface of the tube such that the contact of that outside turbulator edge(s) and the movement thereof effects a scraping action of the inner surface of the tube to clean same. 
     A tube cleaning system  48  of the boiler apparatus is formed by a shaft  50  extending horizontally through the boiler housing  10  above top ends of the tubes  13  with a lever  52  on one end externally to the housing  27  for operation, and pivotal connections respectively indicated at  54  that join the turbulators  42  to the shaft so that they are movable in the longitudinal sliding movement to clean with the outside turbulator edges  45  the inner tube surface as the shaft  50  is pivoted about its axis. 
     More specifically, in the longitudinal sliding movement the respective turbulator is moved relative to the tube from an operating position to a raised position and back to the operating position, with the contact of the respective outer edge of the strip and the movement thereof relative to the tube effecting a cleaning of the inner surface  24 A to remove combustion products deposited on the inner surface by the heated gases. 
     The tubes  13  are arranged each to one side of the next so as to generally form a row parallel to an axis of the shaft such that the row extends across a width of the housing  27  from one side wall  29 C to the opposite side wall  29 D. 
     More specifically, in the illustrated arrangement the tubes arranged side-by-side form a zig-zagging pattern relative to the axis of the shaft which is a central axis through the zig-zagged pattern of the row of tubes. Thus, as best shown in top plan view in  FIG. 3 , the tubes  13  relative to the shaft are disposed in an alternating arrangement so that the tubes are staggered relative to one another about the shaft  50  which is central therefor. Furthermore, the tubes are spaced longitudinally apart one from the other along the length of the shaft. 
     The pivotal connection  54  includes a bracket  56  forming a channel which is receivable over a lengthwise (longitudinal) portion of the shaft in a manner covering a portion of a circumferential transverse periphery of the shaft  50 . 
     Thus, in transverse cross-section as best shown in  FIG. 4  the bracket is generally C-shaped so as to generally follow part of the circumferential transverse periphery of the shaft. 
     Furthermore, the bracket therefore has an open side at  59  through which the shaft  50  in fixed position in the housing is passed as the bracket  56  is placed thereover. 
     Opposite the open side  59  there is provided a plate forming an ear  61  oriented in a radial plane of the shaft normal to the shaft axis and which extends outwardly therefrom in a radial direction. It is from the ear where the turbulator  42  depends downwardly into the respective tube  13 . The strip  44  is supported in fixed relation to a hanger  63  pivotally connected at the ear  61  by a pivot pin P defining a pivot axis parallel to and spaced radially from the shaft axis, thereby forming the pivotal connection  54 . A top end of the strip  44  is hooked through an aperture at a bottom of the hanger  63  so as to connect the turbulator thereto. 
     There is provided a removable fastening pin  66  to attach the bracket in fixed relation to the shaft. The fastening pin  66  passes through apertures  68 ,  69  in each of the bracket  56  and the shaft  50  which are cooperative with the pin and can be properly aligned with one another when the bracket is inserted over the shaft. In the illustrated arrangement, the set of cooperating apertures  68  in the bracket and that aperture  69  in the solid shaft extending diametrically therethrough are aligned linearly along a diameter of the shaft. 
     The fastening pin  66  comprises an elongate rigid pin portion  71  with a smooth cylindrical surface which is passed diametrically of the shaft  50  through the two sets of apertures  68 ,  69 . Thus, it will be appreciated that in the illustrated arrangement the pin portion is not threadably mated with the shaft or bracket at the respective apertures  68 ,  69 , whereby installation and removal of the pin  66  may thus be expedited. Further to the pin portion, a clip portion  72  of the fastening pin is provided which is pivotally connected at one end  71 A of the pin portion. The clip portion is curved so that from its connected end to its terminus  72 B the clip portion follows an arcuate curving path. As such, the clip portion is shaped to traverse a portion of the circumferential periphery of the shaft in order for the terminus  72 B to matingly close the pin  66  at a distal end of the pin portion. Thus, the clip portion is resiliently flexible so that the terminus may be slid over an end portion of the pin portion  71  that protrudes beyond an outer face of the bracket  56 . For example, the pin portion  71  includes a circumferentially extending groove which matingly receives the terminus of the clip portion to matingly close the pin  66  which is an arrangement common to the field of fastening pins. The pin portion  71  where the clip portion  72  is hinged thereat is enlarged radially of that part of the pin portion passing through the shaft  50  so as to provide a circumferentially extending surface for resting against an outer face at a top of the bracket  56 . 
     Thus, each turbulator  42  is attached to the common shaft  50 , on which all turbulators are supported, independently of every other turbulator. As such, each turbulator is removable from the shaft and thus from within the respective tube for cleaning without having to disassemble an entirety of the boiler apparatus&#39; tube cleaning system  48 . 
     Removal of the respective turbulator from the tube may be achieved by removing the fastening pin  66 , rotating the turbulator still within the tube so as to displace the bracket from its position by which its shape follows the circumference of the shaft, and then lifting the turbulator vertically upwardly out of confinement within the tube. The reverse of these steps may be performed in order to insert the respective turbulator into the corresponding one of the tubes, for example after cleaning of the turbulator. 
     Additionally, it will be appreciated that an end of the shaft  50  opposite the lever  52  is supported in a receptacle at a wall of the heat exchanger container  20  and a portion of the shaft adjacent the lever is supported in a tubular sleeve so as to carry the shaft in its pivotal movement. 
     Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.