Patent Publication Number: US-6668914-B2

Title: Multiple tube bundle heat exchanger

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part application of U.S. application Ser. No. 09/822,032, filed Mar. 29, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a multiple tube bundle heat exchanger. In other words, the invention relates to a heat exchanger configuration that includes a plurality of flow-interconnected heat exchange tube bundles. The flow interconnection may relate either to the medium flowing through the tube bundles or to the medium flowing around the tube bundles, or to both. 
     Multiple tube bundle heat exchangers are already in the prior art. For example, Switzerland Patent No. CH 586 882 describes a counter-current tube bundle heat exchanger in the form of an in-series, tube bundle heat exchanger. In that heat exchanger, a common housing has disposed in it a plurality of tube bundles that are flow-connected in series and through which the primary medium flows in succession. All the tube bundles run between two tube sheets common to all the tube bundles, and the plenum chambers above each of the tube sheets are subdivided into partial chambers to form an inflow distributor chamber for the primary medium for distribution to the tubes of the first tube bundle, then a series of connecting chambers, disposed above the one tube sheet or the other, for connecting respectively the outlet ends of the tube bundle to the inlet ends of an adjacent tube bundle, and, finally, an outlet collecting chamber above the outlet ends of the last tube bundle in the flow series connection. Between the individual tube bundles are disposed, in the housing, partitions that respectively have fluid transfer orifices near one tube sheet or the other so that the secondary medium flows first into a first tube bundle chamber and then passes through the fluid transfer orifices from tube bundle chamber to tube bundle chamber and finally out of the last tube bundle chamber into an outlet. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the invention to provide a multiple tube bundle heat exchanger that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that provides a configuration making it possible, on a modular basis, to construct economically the most diverse tube bundle heat exchanger configuration that is variable to the greatest possible extent both in terms of size and in terms of the flow configuration or of the routing of the primary medium and secondary medium. 
     With the foregoing and other objects in view, there is provided, in accordance with the invention, a multiple tube bundle heat exchanger, including a number of tube bundles, each of the tube bundles being formed as a self-contained integral unit having two axially spaced tube sheets and a plurality of heat exchanger tubes each with opposite axial ends, the two tube sheets mounted at the opposite axial ends of the heat exchanger tubes, a casing having a tubular portion substantially coextending with the tube bundles and having an interior subdivided by partitions into a plurality of axial chambers, a number of the axial chambers corresponding to the number of the tube bundles, each of the chambers receiving one of the tube bundles, two opposite axial ends, and flanges disposed at the two opposite axial ends, and head pieces removably mounted to the flanges, each of the head pieces having walls defining at least a first wall portion of a plenum chamber, and the two tube sheets of each of the tube bundles respectively sealing an adjacent one of the head pieces and forming at least a second wall portion of a respective plenum chamber of the adjacent one head piece. 
     In accordance with another feature of the invention, the partitions have at least one fluid transfer opening adjacent at least one of the two opposite axial ends of the tubular portion to allow fluid flowing through the interior of the tubular portion to pass between adjacent ones of the chambers. 
     In accordance with a further feature of the invention, the at least one fluid transfer opening is selectively obturated. 
     In accordance with an additional feature of the invention, the partitions have fluid transfer openings adjacent the two opposite axial ends of the tubular portion to allow fluid flowing through the interior of the tubular portion to pass between adjacent ones of the chambers. 
     In accordance with yet another feature of the invention, the fluid transfer openings are selectively obturated. 
     In accordance with yet a further feature of the invention, there is provided a separate intermediate piece disposed between at least one of the two opposite axial ends of the tubular portion and an adjacent one of the head pieces to form an axial extension of the tubular portion. 
     In accordance with yet an added feature of the invention, the intermediate piece has partitions forming axial extensions of the partitions of the tubular portion. 
     In accordance with yet an additional feature of the invention, the partitions of the intermediate piece have fluid transfer openings to allow fluid to pass between adjacent ones of the chambers in the tubular portion. 
     In accordance with a concomitant feature of the invention, there is provided a separate intermediate piece disposed between at least one of the two opposite axial ends of the tubular portion and an adjacent one of the head pieces to form an axial extension of the tubular portion, the intermediate piece having partitions forming axial extensions of the partitions of the tubular portion, and the partitions of the intermediate piece having fluid transfer openings to allow fluid to pass between adjacent ones of the chambers in the tubular portion. 
     The concept according to the invention provides for using standard heat exchanger tube bundles together with standard housing sub-assemblies that allow a multiplicity of combination possibilities and, of course, also heat exchanger configurations of different size. 
     Other features that are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is illustrated and described herein as embodied in a multiple tube bundle heat exchanger, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a counter-current heat exchanger according to the invention constructed from a multiple configuration of tube bundles and having a parallel flow connection of the tube bundles; 
     FIG. 2 is a cross-sectional view of an alternative embodiment of the counter-current heat exchanger of FIG. 1 with a plurality of tube bundles, flow-connected in series; 
     FIG. 3 is a cross-sectional view of an alternative embodiment of the counter-current heat exchanger of FIG. 1 with a plurality of tube bundles, flow-connected in parallel, and with an alternative housing configuration; and 
     FIG. 4 is a cross-sectional view of an alternative embodiment of the counter-current heat exchanger of FIG. 3 with a plurality of tube bundles, flow-connected in series, and with a housing configuration developed in relation to the configuration according to FIG.  2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In all the figures of the drawing, sub-features and integral parts that correspond to one another bear the same reference symbol in each case. 
     Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown a heat exchanger having a casing and a plurality of tube bundles disposed therein. 
     The casing is made of a tubular casing portion  1 , on which are disposed an inlet connection piece  11  and an outlet connection piece  12  respectively introducing and discharging a secondary medium into and out of the casing spaces. On both axial ends of the tubular casing portion  1  are flanges  13  and two head pieces  2 ,  3 , which are disposed adjacent to the opposite axial ends of the tubular casing portion  1 . The head pieces  2 ,  3  respectively have an inlet and an outlet connection piece  21 ,  31  for a primary medium to be conducted through the tube bundles. The head pieces  2 ,  3  each have an associated cover plate  22 ,  32  that can be clamped together with the flanges  13  of the casing  1  by screws or threaded rods  23 ,  33 . 
     A plurality of tube bundles  5 , specifically, in the exemplary embodiment illustrated, three tube bundles, which are designated  5 A,  5 B, and  5 C, are installed in the casing. Each tube bundle includes a number of parallel heat exchanger tubes  51  disposed at distances from one another and two tube sheets  52  are respectively connected to these and located at the two opposite axial ends of the tube bundle. 
     Each tube bundle comprising a number of heat exchanger tubes  51  and the associated tube sheets  52  forms a separate module in the form of an integral unit and is installed as such in the casing. The seals  53  used for sealing off between the tubular casing portion  1 , head pieces  2 ,  3 , and the tube sheets  52  are illustrated only schematically in the drawings and can be implemented as O-ring seals or any other desired way, as required. 
     The interior of the tubular casing portion  1  is subdivided by partitions  14  into a number of chambers  10 A,  10 B,  10 C corresponding to the number of tube bundles  5 . The partitions  14  are provided at the top and bottom with passage orifices  15  through which the individual chambers  10 A,  10 B,  10 C are connected to one another. The passage orifices can be selectively closed. 
     As can be seen, the plenum chambers, which are formed in the head pieces  2 ,  3 , are not subdivided, but extend over all three tube bundles, so that a parallel flow through the three tube bundles  5 A,  5 B,  5 C takes place. The three tube bundles  5 A,  5 B,  5 C are, therefore, flow-connected in parallel. 
     FIG. 2 shows a configuration that, again, includes a tubular casing portion  1  with three tube bundles  5 A,  5 B,  5 C installed therein. The construction of the casing with a tubular casing portion  1 , head pieces  2 ,  3 , and connection pieces  11 ,  12 ,  21 ,  31  for the media involved in the heat exchange and the subdivision of the casing interior by partitions  14  into three chambers  10 A,  10 B,  10 C correspond to the configuration according to FIG.  1 . 
     The three tube bundles  5 A,  5 B,  5 C in FIG. 2 are constructed in the same way as those in FIG. 1 and, again, respectively include heat exchanger tubes  51  and two tube sheets  52  at the two opposite axial ends of each tube bundle  5 A,  5 B,  5 C, again, constituting an integral unit or separate module made up of these parts. 
     However, as compared with the configuration according to FIG. 1, in the configuration according to FIG. 2, the head pieces  2 ,  3  and the partitions  14  in the casing  1  are modified such that, in the configuration in FIG. 2, the three tube bundles are flow-connected in series. Also, the secondary medium flowing in through the connection piece  11  and flowing out through the connection piece  12  is routed, in all three tube bundles, in counter-current to the primary medium that flows in through the connection piece  21  and flows out through the connection piece  31  and that flows in succession through the heat exchanger tubes  51  of the three tube bundles. For that purpose, the head pieces  2  and  3  are modified such that an inlet plenum chamber  24  is formed above the inlet end of the first tube bundle  5 C, as seen in the direction of flow of the primary medium. Also, a transfer chamber  35 ,  25  is formed respectively in the head pieces  3 ,  2  for transferring the primary medium between the adjacent ends of two fluidically successive tube bundles (from  5 C to  5 B through the transfer chamber  35  or from  5 B to  5 A through the transfer chamber  25 ), and an outflow plenum chamber  36  is formed above the outflow end of the last tube bundle, as seen in the direction of flow of the primary medium, that is to say  5 A. Partitions  27 ,  37  for appropriately subdividing the head piece interior spaces into the corresponding chambers are, therefore, formed in the head pieces  2 ,  3 . 
     Only one transfer orifice  15  is provided in each of the partitions  14  and is located near the respective tube plates so that a secondary medium must in each case flow, in counter-current to the medium flowing through the tube bundles, through essentially the entire axial length of the respective casing chamber until it pass through the respective transfer orifice  15  into the adjacent casing chamber. 
     For constructing configurations according to FIGS. 1 and 2, standard partitions  14  may be used, which, as illustrated in FIG. 1, may have, at both axial ends, transfer orifices, one of which is closed in each case to produce a configuration according to FIG.  2 . 
     Different head pieces with or without partitions  27 ,  37  may also be kept ready, so that configurations according to FIGS. 1 and 2 can be produced, as required, from such elements in a modular manner. 
     FIGS. 3 and 4 show configurations similar to those according to FIGS. 1 and 2 of a multiple tube bundle heat exchanger with tube bundles flow-connected in parallel (FIG. 3) or with tube bundles flow-connected in series (FIG.  4 ). Identical or corresponding parts are, again, given the same reference symbols as in FIGS. 1 and 2. 
     The tube bundles  5 A,  5 B,  5 C (of which there are, again, for example, three in each case) correspond to those according to FIGS. 1 and 2. The head pieces  2 ,  3  also correspond to those according to FIGS. 1 and 2. The same applies to the tubular casing portion  1  with the connection pieces  11 ,  12 . 
     The configurations according to FIGS. 3 and 4, however, differ from the configurations according to FIGS. 1 and 2 in a modification or development of the casing structure. For, in the configurations according to FIGS. 3 and 4, the partitions  14  are configured without transfer orifices, that is to say, are completely closed. Instead, in the configurations according to FIGS. 3 and 4, the head pieces  2 ,  3  are each supplemented by an intermediate piece  4  that is disposed between the respective head piece and the flange  13  of the tubular casing portion  1  and that forms prolongations of the partitions  14 , or, where fluid shall pass between adjacent casing chambers, have a transfer orifice  41 . 
     As a result, the tubular casing portion  1  of the casing, together with the partitions  14 , can be configured as a standard part, while different intermediate pieces  4  can be kept ready, as required, as parts to be used in a modular manner to produce transfer orifices between the casing chambers. 
     In configurations according to FIGS. 3 and 4, if the intermediate pieces  4  have sufficient axial length, the connection pieces for the tubular casing portion (in the embodiments illustrated, designated by  11  and  12  and disposed on the tubular casing portion  1 ) may also be disposed on the intermediate pieces  4 . In such a case, it is possible not only to mount one or both connection pieces laterally on the respective intermediate piece  4 , but also to configure it axially and lead it through the respective head piece  2 ,  3 . 
     The above embodiments were described as counter-current heat exchangers by virtue of the arrows indicated in the drawings. It goes without saying that they may also be operated in the same way as co-current heat exchangers, for which purpose only the direction of flow of one of the two media needs to be reversed. 
     The concept according to the invention makes it possible to construct any desired heat exchangers using standard components. In particular, the tube bundles may be configured as standard components, from which any desired multiple tube bundle heat exchanger configurations of different size can be constructed, regardless of the intended operation as co-current or counter-current heat exchangers. For heat exchangers of different sizes, different housing structural parts, to be precise casings and head pieces, may be kept ready, these respectively being configured to receive a specific number of tube bundles, or variable block configurations of such casing structural parts may be provided. By using appropriate head pieces, to be precise, one for the tube bundles operating in parallel and one for the tube bundles connected in series, heat exchanger configurations can be constructed as required from relatively few basic components in a modular manner and, therefore, highly economically.