Abstract:
A cell of a recuperator has a passage therein having a first end and a second end. In use a fluid passes through the passage under pressure. The cell must be tested to determine an operational efficiency or leakage within the passage. A pair of sealing mechanisms is positioned at a respective one of the first end and the second end of the passage. A vacuum is pulled across the passage and a rate of leakage is monitored to define an operational cell and a failed cell.

Description:
TECHNICAL FIELD 
     This invention relates generally to a heat exchanger or more explicitly to a recuperator and more particularly to a method and an apparatus for construction of the cells making up the recuperator. 
     BACKGROUND 
     A recuperator is made from a plurality of cells. The cell is made from a plurality of components parts. Such components being a pair of folded sheets having a donor side and a recipient side. A pair of wing portions defining an inlet passage and an outlet passage. In many cells, guide vanes are positioned in the respective wing portions. And, a plurality of spacer bars are positioned between the pair of folded sheets. The components of the cell are welded together. An example of such a welded cell and recuperator is shown in U.S. Pat. No. 5,060,721 issued on Oct. 29, 1991 to Charles T. Darragh. 
     During the assembly of the cells and the recuperator, the interface of the components are welded. The effectiveness of the welding process used to form the cells is in many instances depend on the fitting relationship of the components, the resulting configuration of the interface of the components and the welding process itself. The results of these variables in some instances results in a leaking cell, leakage between the donor side and the recipient side. Thus, it is necessary to inspect or check the reliability of the welded cell against leaks prior to installing into the recuperator. Inspection or checking must be done in a reliable and cost effective manner. 
     The present invention is directed to overcome one or more of the problems as set forth above. 
     SUMMARY OF THE INVENTION 
     In one aspect of the invention, an apparatus for testing a leak within a cell of a recuperator is disclosed. The cell has a plurality of components, such components being a plurality of primary surface sheets, a plurality of spacer bars and a pair of guide vanes. The apparatus has a table having a bottom portion and a top portion. The top portion is movable between a closed or testing position and an open or non testing position. A pair of sealing mechanisms is movable between an open or non testing position and a closed or testing position. A vacuum pump is operatively connected to the pair of sealing mechanisms and a controller is operatively connected to the table, the pair of sealing mechanisms and the vacuum pump. 
     In another aspect of the invention, a method of testing for a leak within a cell for a recuperator is disclosed. The cell has a plurality of components, such components being a plurality of primary surface sheets, a plurality of spacer bars and a pair of guide vanes. The method has the steps of positioning the cell on a bottom portion of a table with a top portion of the table being in an open or non testing position. Moving the top portion into a closed or testing position. Securing the top portion in the closed or testing position to the bottom portion of said table. Actuating a controller. Moving a pair of sealing mechanisms from an open or non testing position to a closed or testing position. Actuating a vacuum pump. Defining a status of the cell by differentiating between an operational cell and a failed cell. Unsecuring the top portion from the bottom portion of the table. Moving the top portion into the open or non testing position. And, removing the cell from the table. 
     In another aspect of the invention, a system for testing a cell for use in a primary surface recuperator is disclosed. The system has an input station from which the cell after being assembled is made available for testing. A testing station includes a table, a pair of sealing mechanisms, a controller, a vacuum pump and a readout station. The table has a top portion and a bottom portion. The top portion is movable between an open or non testing position and a closed or testing position. In the closed or testing position of the top portion the cell is positioned in the bottom portion and the top portion is positioned in the closed or testing position. The pair of sealing mechanisms is attached to the bottom portion of the table and is movable between an open or non testing position and a closed or testing position. In the closed or testing position of the pair of sealing mechanisms the cell has a first end of a passage in contacting sealing relationship with a one of the pair of sealing mechanisms and a second end of the passage in contacting sealing relationship with an other one of the pair of sealing mechanisms. The controller is in communication with a plurality of sensors. A portion of the plurality of sensor communicates a signal to the controller defining one of a position at which the closed or testing position is operational and a position at which the closed or testing position is not operational. The vacuum pump is actuated by the controller depending on a plurality of signals from a portion of said plurality of sensors. The readout station defines a status of the cell by differentiating between an operational cell and a failed cell. An output station has a pair of positions, one of the pair of positions is an operational cell position and failed cell position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of a recuperator taken through a plurality of cells; 
     FIG. 2 is a view of one of the plurality of cells partially assembled and used in making the plurality of cells; 
     FIG. 3 is a detailed sectional view of the recuperator showing the plurality of cells and a portion of the finished welds thereon; 
     FIG. 4 is a schematically represented view of an inspection line; 
     FIG. 5 is a view of an inspection table shown in an open or loading position; 
     FIG. 6 is view of the inspection table shown in a closed or testing position; and 
     FIG. 7 is a detailed sectional view of a portion of the inspection table and the sealing mechanism shown in FIG.  6 . 
    
    
     DETAILED DESCRIPTION 
     As best shown in FIG. 1, a recuperator  10  is formed from a plurality of cells  12 . The recuperator  10  has a plurality of donor passages  14  and a plurality of recipient passages  16  defined therein. Each of the plurality of cells  12  is made from a plurality of primary surface sheets  18 . In this application, a pair of the plurality of primary surface sheets  18  designated as  18 A and having a red color code and  18 B having a black color code is used in making each cell  12 . A plurality of spacer bars  20  and a plurality of guide vanes  22  are also used in making the cell  12 . The plurality of spacer bars  20  are divided into a plurality of donor spacer bars  20 D and a plurality of recipient spacer bars  20 R. And, each of the plurality of spacer bars  20  has a preestablished width “w” extending between a first surface  23  and a second surface  24  and a preestablished thickness “t” extending between a pair of edges  25 . The plurality of guide vanes  22  are divided into a donor guide vane  22 D having an inlet guide vane and an outlet guide vane and a recipient guide vane  22 R having an inlet guide vane and an outlet guide vane. 
     As best shown in FIGS. 1 and 2, each of the pair of primary surface sheets  18 A,  18 B is pleated and defines a donor side  26  and a recipient side  27 . Each of the plurality of primary surface sheets  18 A and  18 B has a center portion  30 , a first wing portion  32  and a second wing portion  34 . In this application, the center portion  30  has a preformed serpentined trapezoidal configuration and each of the first and second wing portions  32 , 34  has a flattened generally triangular configuration. As an alternative, other configurations could be used without changing the jest of the invention. Each of the plurality of primary surface sheets  18 A and  18 B define a plurality of edges  36 . The plurality of spacer bars  20  are position on the primary surface sheet  18 A and  18 B alone the respective one of the plurality of edges  36  in a plurality of precise preestablished locations. As shown in FIGS. 1 and 3, one of the pair of primary surface sheets  18 A and  18 B, on the recipient side  27 , has the recipient inlet guide vane  22 R attached thereto in the first wing portion  32  in a precise preestablished location. And, the same one of the pair of primary surface sheets  18 A and  18 B, on the recipient side  27 , has the recipient outlet guide vane  22 R attached thereto in the second wing portion  34 . Interposed the first wing portion  32  of the pair of primary surface sheets  18 A and  18 B is a recipient inlet passage  50  positioned at a first or inlet end  51  and interposed the second wing portion  34  of the pair of primary surface sheets  18 A and  18 B is a recipient outlet passage  52  positioned at a second or outlet end  53 . As shown in FIG. 3, a plurality of welds  54  are used to complete the assembly of each of the plurality of cells  12  and is further used to assembly the recuperator  10  after each cell has been inspected and tested. 
     As best seen in FIGS. 4 and 5, a testing or inspection system, apparatus and/or line  60  is shown. The testing or inspection line  60  includes a table  62  having a pair of sealing mechanisms  64  being operatively sealable with the one of the plurality of cells  12 . An input station  65  is positioned near the table  62  and has a plurality of welded cells position thereon. An output station  66  is located near the table  62  and has an operational cell position  67  and a failed cell position  68  thereon. 
     The table  62  is interconnected to a controller  69  by a plurality of leads  70  which extend from a plurality of sensors  71 , such as by wires. A source for pulling a vacuum, a vacuum pump  72  is connected to the controller  69  and the pair of mechanism  64 . For example, a pair of hoses  73  are fluidly connected to each of the pair of mechanism  64  and a portion of the plurality of leads  70  interconnect the controller  69  and the vacuum pump  72 . A plurality of switches  74  are operatively connected to the controller  69  and the vacuum pump  72 . A pair of safety devices  76  are operatively attached to the table  62  and the controller  69  and a readout station  78  is operatively attached to the inspection line  60 . 
     As further shown in FIG. 5, the table  62  has a bottom portion  80  and a top portion  82  hingedly connected by a plurality of hinges  84 . As an alternative, a single hinge  84  could be used. The top portion  82  has a generally ladder type configuration being formed by a pair of rails  86  spaced apart by a plurality of rungs  88 . Interposed the plurality of rungs  88  are a plurality of openings  90 . A pair of handles  92  are attached to one of the pair of rails  86  opposite the plurality of hinges  84  and are space one from another. A transparent plate  94  is attached to the top portion  82 . As an alternative, the top portion  82  could be a transparent member. The transparent plate  94  has a substantially flat surface  96 . The table  62  has the top portion  82  shown in an open or loading position  98  in FIG.  5 . The bottom portion  80  has a deck portion  100  having a substantially flat surface  102 . The deck portion  100  is elevated from a table top  103  of the table  62  in a conventional manner, such as a plurality of pillars. The table top  103  has a top surface  104  and bottom surface  105 . The deck portion  100  has a pair of ends  106  and a pair of sides  107 . A plurality of locators  108  are positioned in the deck portion  100  near the respective pair of ends  106  and the pair of sides  107 . In this application, the pair of mechanisms  64  are movably attached to the bottom portion  80  of the table  62  at an angle to each of the intersection of one of the pair of ends  106  and one of the pair of sides  107 . The pair of sealing mechanism  64  are movable to the bottom portion  80  between a plurality of positions to compensate for testing of a variety of shapes and configurations of cells  12 . The pair of mechanisms  64  are operatively aligned with each of the recipient inlet passage  50  and the recipient outlet passage  52  at the respective first end  51  and the second end  53 . The pair of mechanisms  64  are spaced from the respective one of the recipient inlet passage  50  and the recipient outlet passage  52  in an open or non testing position  110 . The plurality of switches  74  are physically located near one of the pair of ends  106  and at one of the pair of sides  107  opposite the one of the pair of side  107  having the plurality of hinges  84  attached thereto. The plurality of switches  74  are positioned in arms reach of an operator and have an off position  116  in which the pair of mechanisms  64  are positioned in the open or non testing position  110 . In this application, the pair of safety devices  76  are positioned near one of the pair of sides  107  being opposite the plurality of hinges  84  and near each of the pair of ends  106 . The pair of safety devices  76  are spaces apart but are within arms length of the operator. The readout station  78  can be one of a visual screen, an audible signal or a visual signal such as a green light for an operational or good cell  12  or a red light for a failed or bad cell  12 . The readout station  78  could also have a printout defining a result of the test or the results could appear on the visual screen for viewing by the operator or to be recorded by the operator. 
     In FIG. 6, the table  62  has the top portion  82  shown in a closed or testing position  120 . The plurality of switches  74  are shown in an on position  122  in which the pair of mechanisms  64  are positioned in the closed or testing position  124  and are sealingly positioned with respect to one of the recipient inlet passage  50  and the recipient outlet passage  52  by a cylinder  126 . The cylinder  126  and linkage  128  is best shown in FIG.  7  and will be further defined later. A cylinder  130  is shown in an extended position. In a closed position, not shown, the cylinder  130  is used to assist in maintaining the top portion  82  in the open or loading position  98 . A lock  132  is shown in a locked position  134 . In FIG. 5, the lock  132  is shown in an unlocked position  136 . As discussed above, in this application, the readout station  78  has a visual screen  138  and a printout mechanism  140 . The printout mechanism  140  includes a printer head  142  having a supply of ink being fed thereto in a conventional manner. The printer head  142  is movable between a plurality of positions to compensate for testing of a variety of shapes and configurations of the cells  12 . 
     As shown in FIG. 7, the pair of sealing mechanisms  64  includes a housing  150  having a plurality of passage  152  therein, only one being shown. A first end portion  154  of each of the plurality of passages  152  is operatively connected to one of the pair of hoses  74 . A second end portion  156  of each of the plurality of passages  152  is operative connected to a seal  158 . For example, the cylinder  126  and the linkage  128  maintain the seal  158  in contacting relationship with the housing  150 . The seal  158  has a generally “T” shaped cross sectional configuration. A top portion  162  of the “T” has a sealing surface  164  positioned at a first end  166 . The top portion  162  has a second end  168  spaced from the first end  166  a preestablished distance. The sealing surface  164  is in contacting relationship with the housing  150  about the plurality of passages  152 . A base portion  170  of the “T” has a first end  172 , shown in phantom, connected to the second end  168  of the top portion  162  and a second end  174  of the base portion  170  is spaced from the first end  172  a preestablished distance and has a sealing surface  176  thereon. A plurality of passages  178 , only one being shown interface between the sealing surface  164  of the top portion  162  and the sealing surface  176  of the base portion  170 . With the pair of mechanisms  64  in the closed or testing position  124  the sealing surface  176  of each seal  158  is in sealing engagement with a respective one of the recipient inlet passage  50  and the recipient outlet passage  52  of the cell  12  being tested. And, with the pair of mechanisms  64  in the open or non testing position  110  the sealing surface  176  of each seal  158  is spaced from the respective one of the recipient inlet passage  50  and the recipient outlet passage  52  of the cell  12  to be tested or having been tested. 
     Each of the pair of pair of mechanisms  64  has one of the cylinders  126  attached to the bottom surface  105  of the table top  103 . A plurality of fasteners  180  threadedly engages into the table top  103  and maintain the respective cylinder  126  in place. The linkage  128  extends from a rod  182  of each cylinder  126  to an arm mechanism  184 . The arm mechanism  184  has a threaded hole  186  therein to which the rod  182  is attached. A locking nut  188  maintains the relative position of the cylinder  126  to the arm mechanism  184 . The arm mechanism  184  is attached to the respective one of the pair of mechanisms  64  and passes through one of a pair of slotted holes  190  in the table top  103 . A pair of slider bars  192  are attached to each of the housing  150  and slidably interfaces with the housing  150  and the top surface  104  of the table top  103 . A similar arrangement can be used to position the readout station  78  if desired. 
     Industrial Applicability 
     In operation, one of the plurality of welded cells  12  is taken from the plurality of cells  12  at the input station  65  and is positioned on the table  62  of the test or inspection line  60 . The donor side  26  of the primary surface sheet  18 A is positioned in contacting relationship with the flat surface  102  of the deck portion  100  of the bottom portion  80 . The plurality of locators  108  positioned near the respective ends  106  and the pair of sides  107  of the deck portion  100  assist in orientation of the individual cell  12  with respect to the pair of sealing mechanisms  64  containing the respective seal  158 . As the operator grasps the pair of handles  92 , the top portion  82  is pivotally closed about the plurality of hinges  84 . Thus, the donor side  26  of the primary surface sheet  18 B is positioned in contacting relationship with the flat surface  96  of the transparent plate  94  of the top portion  82 . With the top portion  82  and the bottom portion  80  of the table  62  having the transparent plate  94  and the transparent deck  100  respectively, it is easy for the operator to insure that the cell  12  being tested or inspected is flat. With the cell  12  flat, the lock  132  is moved into the locked position  136  by the operator. The plurality of switched  74  are engaged to the on position  122  by the operator and the pair of safety devices  76  are depressed or actuated. 
     With all switches  74  and devices  76  in the go position and the signal from the plurality of sensors  71  to the controller  69  activated, the rod  182  of each of the cylinders  126  is extended and each of the pair of mechanisms  64  is moved into the closed or testing position  124 . Thus, the sealing surface  176  of the seal  158  is in contacting and sealing relationship with one of the recipient inlet passage  50  and the recipient outlet passage  52  at there respective first end  51  and second end  53 . And, the sealing surface  164  of the seal  158  is in contacting and sealing relationship with the respective one of the pair of mechanisms  64 . For example, the rod  182  of the cylinder  126  is extended, such as by air pressure, and the linkage  128  connecting with the respective one of the pair of mechanisms  64  is moved from the open or non testing position  110  to the closed or testing position  124 . 
     The vacuum pump  72  is actuated and a vacuum of about 250,000 Pascals (about 36 pounds per square inch) is drawn within the recipient passage  16  between the recipient inlet passage  50  and the recipient outlet passage  52 . After attaining the preestablished vacuum the vacuum pump  72  is deactivated. A portion of the plurality of sensors  71  monitors the leakage from the recipient passage  16  and the rate of leakage is indicated by the readout station  78 . The results of the test is printed on one of the plurality of spacer bars  20  by the printout mechanism  140 . 
     The lock  132  is unlocked by the operator and the top portion  82  of the table  62  is moved into the open or loading position  98 . The tested cell  12  is removed from the bottom portion  80  of the table  62  and is positioned on the output station  66  at either the operational cell position  67  if passing the test or the failed cell position  86  if failing the test. 
     Thus, the effectiveness of the recuperator  10  is increased by using only cells  12  that pass the test and are positioned in the operational cell position  67  of the output station  66 . The cells  12  which are positioned in the failed position  86  can be reworked or scrapped. With the testing or inspection system, apparatus and/or line  60  the effectiveness and efficiency of the recuperator  10  is increased. 
     Other aspects and advantages of this invention ca be obtained from a study of the drawings, the disclosure, and the appended claims.