US3656548A

US3656548A - Self-positioning baffle for shell and tube heat exchangers

Info

Publication number: US3656548A
Application number: US31338A
Authority: US
Inventors: Desmond M Donaldson
Original assignee: Borg Warner Corp
Current assignee: LONG MANUFACTURING Ltd A CORP OF CANADA
Priority date: 1970-04-23
Filing date: 1970-04-23
Publication date: 1972-04-18
Anticipated expiration: 1989-04-18
Also published as: DE2119873A1; CA923490A; GB1316514A; FR2086290A1; BR7102252D0; DE2119873B2; FR2086290B1; ZA711986B

Abstract

A shell and tube heat exchanger including a plurality of transverse baffle plates which may be made of a resilient formable organic compound, the baffle plate adapted to be disposed within the shell and includes positioning means associated with the baffle plate axially projecting from at least one side thereof adapted to matingly engage an axially adjacent baffle plate such that adjacent baffle plates are spaced in a relatively fixed position both axially and rotationally with respect to each other and a method for making same.

Description

United States Patent Donaldson [45] Apr. 1, 1972 [54] SELF-POSITIONING BAFFLE FOR 2,498,145 2/1950 Tinker SHELL AND TUBE HEAT 2,855,206 10/1958 Haviland...

1,904,875 4/1933 Metzgar EXCHANGERS 2,608,387 8/1952 Randall ..257/44 [72] Inventor: Desmond M. Donaldson, Oakville, On-

tario, Canada Primary Examiner-Charles Sukalo Assistant Examiner-W. C. Anderson Asslgl'leel Corporation Chlcago, AttorneyDona1d W. Banner, William S. McCurry and John 221 Filed: Apr. 23, 1970 Bulchel [211 App]. No.: 31,338 [57] ABSTRACT A shell and tube heat exchanger including a plurality of trans- [52] U.S. Cl ..165/159 verse baffle plates which may be made of a resilient formable [51] lnt.Cl organic compound, the baffle plate adapted to be disposed [58] Field of Search ..165/159, 161; 122/510; within the shell and inc udes positioning means associated 1 o gg A 9 R, 93; 29/1573 with the baffle plate axially projecting from at least one side thereof adapted to matingly engage an axially adjacent baffle [56] References Cited plate such that adjacent baffle plates are spaced in a relatively fixed position both axially and rotationally with respect to UNITED STATES PATENTS each other and a method for making same.

3,400,758 9/1968 Man Suk Lee ..165/159 26 Claims, 12 Drawing Figures PAIENTEMPR 18 I972 sum 10!: 2

SELF-POSITIONING BAFFLE FOR SHELL AND TUBE HEAT EXCHANGERS BACKGROUND OF THE INVENTION This invention relates to heat exchangers of the shell and tube type and more specifically, to a heat exchanger incorporating a self-positioning baffle plate.

Baffle plates are used in shell and tube heat exchangers for two primary reasons:

a. as a support for heat exchange tubes which extend through the length of the heat exchangers, and

b. as a means for directing a heat exchange fluid to follow a tortuous path across the tubes to obtain maximum heat exchange exposure.

During construction of the heat exchanger, it is necessary to axially space or position the baffle plates along the length of the heat exchanger to achieve both the desired support and flow path. A variety of methods have been employed to so space or position these baffles.

A commonly employed method is to use a baffle in which the tube hole is a relatively tight fit on the tube. Thus, after inserting the tubes through the tube holes there is considerable friction between baffle and tubes which may be enough to hold the baffle in place. Unfortunately, sometimes, through vibration, the baffle may become loose and slip out of position or alternatively, cut through the tube.

An alternate method is to solder, braze or weld the baffles to the tubes. A disadvantage of this method is that the heat of soldering, brazing or welding anneals and thus weakens the tubes.

Separate mechanical means are quite frequently employed. These consist sometimes of longitudinal bars or rods onto which the baffles are threaded, with intermediate sections of tubes to keep the baffles properly spaced. In another separate mechanical method, notched or slotted longitudinal bars are fitted over the baffles at their outer periphery. The engagement of the baffles and the notches keeps them in place. These two methods are disclosed in U.S. Pat. Nos. 2,873,098 and 3,240,267.

Another method of positioning the baffles with respect to each other and the shell is to constrict the outer shell locally, so as to hold or restrict the battle from axial movement. Various means of this type are described in U.S. Pat. Nos. 1,794,336, 2,978,226 and 3,240,267.

The present invention is an improvement over all the prior art methods discussed in that it provides a baffle which has incorporated, either as an integral part or as a preassembled attachment, positioning means projecting from one or both sides designed to keep the series of baffles and their headers properly oriented in their designated positions.

The present invention further provides baffles incorporating positioning means which include means of interlocking with other baflles so that a series of baffles may be preassembled into a tube cage or framework into which the tubes may be in serted, thus greatly simplifying the assembly procedure. Such an arrangement provides accurate, reliable and simple means of initially positioning all of the baffles both axially and rotationally with respect to each other and ensures that during the process of assembling the tubes to the heat exchanger, the baffles will remain properly positioned. It further ensures that during the life of the heat exchanger, the baffles will be held 6 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a central longitudinal section of a heat exchanger incorporating the principles of the present invention.

FIG. 2 is a plan view of one of the heat exchanger baffles.

FIG. 3 is a side viewof the bafile shown in FIG. 2.

FIG. 4 is a detailed cross-section to a somewhat enlarged scale on the line 4-4 of FIG. 2.

FIG. 5 is a detailed cross-section to a somewhat enlarged scale on the line 5-5 of FIG. 2.

HG. 6 is a detailed cross-section to a somewhat enlarged scale on the line 6-6 of FIG. 2.

FIG. 7 is'a detailed cross-section in an enlarged scale on the line 7--7 of FIG. 3.

FIG. 8 is a detailed cross-section in an enlarged scale on the line 8-8 of FIG. 3.

FIG. 9 is a perspective view of an alternative embodiment of a baffle incorporating the features of the present invention.

FIG. 10 is a side view showing one modified construction of the bafile plate.

FIG. 11 is a side view showing another modified construction of the bafile plate.

FIG. 12 is a side view showing still another modification of the baffle plate.

Referring now to FIG. 1, there is shown a heat exchanger generally identified as 10. The heat exchanger includes a pair of headers 11 and 12, a pair of

tube plates

15 and 16, each connected to a header, and a shell 17 connected between the

tube plates

15 and 16. A fluid inlet 20 is defined in the tube plate 16 for a first heat exchange fluid. Conduit means 21 are connected to the fluid inlet. A fluid outlet 22 is defined in the tube plate 15 for the first heat exchange fluid. Conduit means 25 are connected to the fluid outlet 22. A fluid inlet 26 is defined in the header 12 for a second heat exchange fluid. A fluid outlet 27 is defined in the header 12 for the second heat exchange fluid. An inlet chamber 30 is defined by the header 12 adjacent the fluid inlet 26. An outlet chamber 31 is defined by the header 12 adjacent the outlet 27. The header 12 is provided with a central diametrical partition 32 which separates the inlet chamber 30 from the outlet chamber 31. A fluid chamber 33 is defined by the header 11.

A plurality of parallel

heat exchange tubes

34 and 35 are provided in any suitable number and arrangement in accordance with standard practice and extend between the

tube plates

15 and 16, their end portions extending through a series of openings 36 defined by the tube plates. The tubes 34 are in communication with the inlet chamber 30 and the tubes 35 are in communication with the outlet chamber 31. Both sets of

tubes

34 and 35 are in communication with the fluid chamber 33. The tubes are sealed to the tube plates in any of a number of standard manners, such as by brazing.

The tubes are supported between the

tube plates

15 and 16 by a series of baffles 37. As best illustrated in FIG. 2, each of the bafiles 37 comprises a generally circular piece having a chordal segment removed from one side to afford a passage for the first heat exchange fluid. The baffles are arranged alternately in spaced relation with the removed segment of alternate baffles on opposite sides of the heat exchanger shell 17 to provide a tortuous path, as shown by the arrows in FIG. 1, for a first heat exchange fluid from the inlet 20 at one end of the shell to the outlet 22 at the other end of the shell. The baffles are provided with a plurality of apertures 40 through 5 which are inserted the

heat exchange tubes

34 and 35.

As best seen in FIG. 3, the baffle comprises a plate member 41 having axially opposed front and

rear surfaces

42 and 45 respectively. Positioning means, generally referred to as 46, are shown connected to the plate member 41 and projecting from at least one side of said front or rear surfaces of said plate.

FIG. 2 shows a first group of positioning means 47 positioned around the periphery of the baffle 37 and a second group of positioning means 50 positioned inwardly of the periphery. Details of the positioning means 47 are best shown in FIGS. 4 and 5 and details of positioning means 50 are best shown in FIG. 6.

The positioning means 46, shown in FIG. 3, project from both front 42 and rear 45 surfaces of the plate member 41 and include a first end 51 axially extending from the rear surface 45 of the plate 41. The first end 51 includes an axially extending male connector 52. The connector 52 includes a cylindrical portion 55, a tapered end 56 connected to the cylindrical portion 55, and an annular ring 57 positioned on the cylindrical portion 55 and of greater diameter than the cylindrical portion. The positioning means 46 also includes a second end 60 axially extending from the front surface 42 of the plate member 41. The second end 60 defines an axially inwardly extending socket connection 61. The socket connection 61 includes a generally cylindrical portion 62 and an annular groove 65 of greater diameter than the cylindrical portion 62. The socket connection 61 is adapted to matingly receive a male connector 52 of an adjacent baffle plate.

The male connector 52 and the socket connection 61 are designed such that when the male connector is inserted into the socket connection, the annular ring 57 deforms slightly upon entering the cylindrical portion 62 and upon further insertion is allowed to expand into the annular groove 65.

Such an arrangement assures a positive connection between adjacent baffle plates which can only be separated upon exerting a separation force of a higher magnitude than would normally be encountered in the operation of such a heat exchanger. Such a connection serves to position baffle plates both axially and rotationally with respect to adjacent baffle plates and to restrain relative axial and rotational movement between these baffle plates. The positioning means 46 may be either an integral part of the baffle plate or a preassembled attachment. Either the baffle plate or the positioning means or both may be made of a resilient formable organic compound. The compounds that have been found suitable for use in this capacity have been such materials as treated nylon (polyamides) and the high temperature polyesters such as polyaryl ether, however, other thermoplastic materials would be equally useful.

FIG. 9 shows a modified form of baffle plate including positioning means 66 axially extending from a front surface 67 of a baffle plate 70 and defining axially extending male connections 71. Other positioning means 72 are connected to the baffle plate 70 and extending from the front surface 67 in the same direction as the positioning means 66. The positioning means 72 define axially inwardly extending socket connections 75. A similar arrangement of positioning means 76 and 77 are shown extending from a rear surface 80 of the baffle plate 70. The positioning means 76 define socket connections and the positioning means 77 define male connectors.

FIG. shows an alternative embodiment of a baffle which includes a baffle plate 81 of corrugated cross-section. Such a construction is felt to be stronger than baffle plates formed in a single plane. The baffle 81 includes positioning means 82 and 85 of the type previously described.

FIG. 11 shows an alternative embodiment of a baflle plate 86 which includes stiffening ribs 87 connected to the baffle plate to add rigidity.

FIG. 12 discloses an alternative embodiment of a baffle plate assembly which includes extensions 90 which are adapted to each end to matingly engage the positioning means 91 of

adjacent baffles

92 and 95 and serve to space the baffles axially further apart than the positioning means would allow.

The operation of the shell and tube heat exchanger 10, as shown in FIG. 1, is as follows. The second heat exchange fluid is communicated to the fluid inlet 26 and flows to the inlet chamber 30 where it is communicated to all of the various heat exchange tubes 34 in communication with the chamber 30. The fluid travels through the tubes 34 into the fluid chamber 33. Fluid passes from the fluid chamber 33 into a second set of heat exchange tubes 35 through which the fluid flows to fluid chamber 31. Fluid flows from the chamber 31 to the fluid outlet 27. The first heat exchange fluid flows from conduit 21 through fluid inlet 20. The fluid then follows a tortuous path around the baflle plates, as shown by the arrows in FIG. 1, in heat exchange relationship with the

tubes

34 and 35. The tortuous path through which the first heat exchange fluid flows operates to maximize the heat exchange efficiency of this device. The second heat exchange fluid is exhausted from the heat exchanger 10 through fluid outlet 22 and conduit 25.

A preferred method of assembling such a heat exchanger which employs the self-positioning bafi'les previously described comprises assembling an element of the heat exchanger first by forming a tube cage by connecting a plurality of bafile plates one to another by connecting the positioning means of adjacent baffle plates such that the apertures of each baffle plate are substantially axially aligned and such that the baffles are alternately arranged to provide a tortuous path for a first heat exchange fluid; inserting a plurality of heat exchange tubes axially through the tube cage; inserting the assembled tube cage into a shell member; positioning a tube plate at each end of the tube cage and aligning the apertures in the tube plate with the heat exchange tubes; sealing the tubes to the tube plates; and sealing the tube plates to the shell. The headers are then attached to the element by sealing the headers to the tube plates.

Thus it has been shown that a shell and tube heat exchanger has been provided which includes a plurality of transverse baffle plates disposed within the shell which baffle plates include positioning means adapted to engage adjacent baffle plates and to position both axially and rotationally, each baffle plate with respect to its adjacent baffle plates. Further, a baffle plate has been shown which may be made of a resilient formable organic compound. Further, a method of assembling such a heat exchanger has been disclosed which provides an accurate, reliable and economical means of assembling such a heat exchanger.

While this invention has been described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not by way of limitation and the scope of this invention is defined solely by the appended claims which should be construed as broadly as the prior art will permit.

What is clairned is:

1. A baffle for a shell and tube heat exchanger having tubes and a hollow shell, said baffle adapted to be disposed in said shell and comprising a plate member having axially opposed front and rear surfaces and defining a plurality of apertures; positioning means formed as an integral part of said plate member and projecting from at least one of said front or rear surfaces of said plate member, said positioning means having at least one end adapted to grippingly engage at least one axially adjacent baffle plate whereby said gripping engagement is effective to position said baffle plate both axially and rotationally with respect to said adjacent baffle plates and to restrain relative axial and rotational movement between said bafile plates.

2. A baffle as in claim 1 in which said positioning means includes another end adapted to grippingly engage an axially adjacent baffle plate disposed on another side of said bafi'le plate.

3. A baffle as in claim 1 in which one end of said positioning means defines an axially extending male connector.

4. A baffle as in claim 1 in which one end of said positioning means defines an axially inwardly extending socket connectron.

5. A baffle as in claim 1 in which said positioning means extends from both sides of said baffle plate.

6. A baffle as in claim 1 in which said baffle is made of a resilient formable thermoplastic organic compound.

7. A baffle as in claim 1 in which said positioning means is made of a resilient formable thermoplastic organic compound.

8. A baffle as in claim 1 in which a plurality of positioning means are connected to said baffle and project from at least one side of said baffle plates.

9. A baffle as in claim 8 in which some of said positioning means projecting from said one side of said baffle plate define axially extending male connectors and others define axially inwardly extending socket connections.

10. A baffle as in claim 8 in which all of said positioning means projecting from said one side of said baffle plate define axially extending male connections.

11. A baffle as in claim 8 in which all of said positioning means projecting from said one side of said baffle plate define axially inwardly extending socket connections.

12. A shell and tube heat exchanger comprising a hollow shell; heat exchange tube means disposed within said shell; means for passing a first heat exchange fluid inside and through said tube means; means for passing a second heat exchange fluid into and through said shell around said tube means in heat exchange relation with said tube means; a plurality of axially spaced cross-flow baffles arranged within said shell to provide a tortuous path for said second heat exchange fluid, each of said baffles including a plate member having axially opposed front and rear surfaces and defining a plurality of apertures through which said tube means extend; positioning means formed as an integral part of said plate member projecting from at least one side of said plate member, each of said positioning means having at least one end grippingly engaged with an axially adjacent baffle plate such that adjacent baffle plates are relatively fixed both axially and rotationally with respect to said other bafi'le plates.

13. A shell and tube heat exchanger as in claim 12 in which said positioning means includes another end adapted to grippingly engage an axially adjacent baffle plate disposed on another side of said baffle plate.

14. A shell and tube heat exchanger as in claim 12 in which one end of said positioning means defines an axially extending male connector.

15. A shell and tube heat exchanger as in claim 12 in which one end of said positioning means defines an axially inwardly extending socket connection.

16. A shell and tube heat exchanger as in claim 12 including extensions adapted to be disposed between adjacent bafile plates, each end of said extensions adapted to grippingly engage said positioning means of said adjacent bafile plates.

17. A shell and tube heat exchanger as in claim 12 in which said positioning means extends from both sides of said baffle late. p 18. A shell and tube heat exchanger as in claim 12 in which said baffle is made of a resilient formable thermoplastic organic compound.

19. A shell and tube heat exchanger as in claim 12 in which said positioning means is made of a resilient forrnable thermoplastic compound.

20. A shell and tube heat exchanger as in claim 12 in which a plurality of positioning means are connected to each of said bafile plates and project from at least one side of said baffle lates. p 21. A shell and tube heat exchanger as in claim in which some of said positioning means projecting from said one side of said baffle plate define axially extending male connectors and others define axially inwardly extending socket connectrons.

22. A shell and tube heat exchanger as in claim 20 in which all of said positioning means projecting from said one side of said baffle plate define axially extending male connections.

23. A shell and tube heat exchanger as in claim 20 in which all of said positioning means define axially inwardly extending socket connections.

24. A method of assembling an element of a heat exchanger of the tube and shell type employing self-positioning baflle plates which define a plurality of apertures and which include positioning means formed as an integal part of said bafflc plates and projecting from at least one side of said bafile plates, said positioning means having at least one end adapted to grippingly engage an adjacent axially disposed baffle plate, the ste s of the method comprising: forming a tube cage by connec 'ng a plurality of said bafile plates one to another by grippingly joining said positioning means of adjacent baffle plates such that the apertures of each baflle plate are substantially axially aligned and such that the baffles are alternately arranged to provide a tortuous path for a first heat exchange fluid; inserting a plurality of heat exchange tubes axially through the apertures of said bafile plate of said tube cage; inserting an assembled tube cage into a shell member; positioning a tube plate at each end of the tube cage; sealing said heat exchange tubes to said tube plates; sealing said tube plates to said shell.

25. A method of assembling a heat exchanger of the tube and shell type which includes a shell, heat exchange tube means, a pair of tube plates, a pair of headers, and which employes self-positioning baffle plates which define a plurality of apertures and which include positioning means formed as an integral part of said baffle plates and projecting from at least one side of said baffle plates, said positioning means having at least one end adapted to grippingly engage an adjacent axially disposed baffle plate, the steps of the method comprising: forming a tube cage by connecting a plurality of said baffle plates one to another by connecting said positioning means of adjacent bafile plates such that the apertures of each baffle plate are substantially axially aligned and such that the baffles are alternately arranged to provide a tortuous path for a first heat exchange fluid; inserting a plurality of heat exchange tubes axially through the apertures of said baffle plates of said tube cage; inserting an assembled tube cage into a shell member; positioning a tube plate at each end of the tube cage; sealing said heat exchange tubes to said tube plates; sealing said tube plates to said shell; sealing said headers to said tube plates.

26. A method of assembling a tube cage for a heat exchanger of the tube and shell type which employs self-positioning bafile plates defining a plurality of apertures and includes positioning means fonned as an integral part of said baffle plates and projecting from at least one side of said baffle plates, said positioning means having at least one end adapted to grippingly engage the adjacent baffle plate, the steps of the method comprising: joining a first baffle plate to a second baffle plate by grippingly engaging said positioning means of said first baffle plate to said second baffle plate such that said apertures of each baffle plate are substantially axially aligned and such that said bafile plates are alternately arranged to provide a tortuous path for a first heat exchange fluid and such that said joined baffle plates are restrained against either axial or rotational movement with respect to each other; connecting additional bafile plates in a like manner by grippingly engaging the positioning means of one baffle plate to said next adjacent baffle plate such that the apertures of all said baflles are substantially axially aligned and such that said baffles are alternately arranged to provide a tortuous path for a first heat exchange fluid.

Claims

1. A baffle for a shell and tube heat exchanger having tubes and a hollow shell, said baffle adapted to be disposed in said shell and comprising a plate member having axially opposed front and rear surfaces and defining a plurality of apertures; positioning means formed as an integral part of said plate member and projecting from at least one of said fRont or rear surfaces of said plate member, said positioning means having at least one end adapted to grippingly engage at least one axially adjacent baffle plate whereby said gripping engagement is effective to position said baffle plate both axially and rotationally with respect to said adjacent baffle plates and to restrain relative axial and rotational movement between said baffle plates.

2. A baffle as in claim 1 in which said positioning means includes another end adapted to grippingly engage an axially adjacent baffle plate disposed on another side of said baffle plate.

4. A baffle as in claim 1 in which one end of said positioning means defines an axially inwardly extending socket connection.

12. A shell and tube heat exchanger comprising a hollow shell; heat exchange tube means disposed within said shell; means for passing a first heat exchange fluid inside and through said tube means; means for passing a second heat exchange fluid into and through said shell around said tube means in heat exchange relation with said tube means; a plurality of axially spaced cross-flow baffles arranged within said shell to provide a tortuous path for said second heat exchange fluid, each of said baffles including a plate member having axially opposed front and rear surfaces and defining a plurality of apertures through which said tube means extend; positioning means formed as an integral part of said plate member projecting from at least one side of said plate member, each of said positioning means having at least one end grippingly engaged with an axially adjacent baffle plate such that adjacent baffle plates are relatively fixed both axially and rotationally with respect to said other baffle plates.

16. A shell and tube heat exchanger as in claim 12 including extensions adapted to be disposed between adjacent baffle plates, each end of said extensions adapted to grippingly engage said positioning means of said adjacent baffle plates.

17. A shell and tube heat exchanger as in claim 12 in which said positioning means extends from both sides of said baffle plate.

18. A shell and tube heat exchanger as in claim 12 in which said baffle is made of a resilient formable thermoplastic organic compound.

19. A shell and tube heat exchanger as in claim 12 in which said positioning means is made Of a resilient formable thermoplastic compound.

20. A shell and tube heat exchanger as in claim 12 in which a plurality of positioning means are connected to each of said baffle plates and project from at least one side of said baffle plates.

21. A shell and tube heat exchanger as in claim 20 in which some of said positioning means projecting from said one side of said baffle plate define axially extending male connectors and others define axially inwardly extending socket connections.

24. A method of assembling an element of a heat exchanger of the tube and shell type employing self-positioning baffle plates which define a plurality of apertures and which include positioning means formed as an integral part of said baffle plates and projecting from at least one side of said baffle plates, said positioning means having at least one end adapted to grippingly engage an adjacent axially disposed baffle plate, the steps of the method comprising: forming a tube cage by connecting a plurality of said baffle plates one to another by grippingly joining said positioning means of adjacent baffle plates such that the apertures of each baffle plate are substantially axially aligned and such that the baffles are alternately arranged to provide a tortuous path for a first heat exchange fluid; inserting a plurality of heat exchange tubes axially through the apertures of said baffle plate of said tube cage; inserting an assembled tube cage into a shell member; positioning a tube plate at each end of the tube cage; sealing said heat exchange tubes to said tube plates; sealing said tube plates to said shell.

25. A method of assembling a heat exchanger of the tube and shell type which includes a shell, heat exchange tube means, a pair of tube plates, a pair of headers, and which employes self-positioning baffle plates which define a plurality of apertures and which include positioning means formed as an integral part of said baffle plates and projecting from at least one side of said baffle plates, said positioning means having at least one end adapted to grippingly engage an adjacent axially disposed baffle plate, the steps of the method comprising: forming a tube cage by connecting a plurality of said baffle plates one to another by connecting said positioning means of adjacent baffle plates such that the apertures of each baffle plate are substantially axially aligned and such that the baffles are alternately arranged to provide a tortuous path for a first heat exchange fluid; inserting a plurality of heat exchange tubes axially through the apertures of said baffle plates of said tube cage; inserting an assembled tube cage into a shell member; positioning a tube plate at each end of the tube cage; sealing said heat exchange tubes to said tube plates; sealing said tube plates to said shell; sealing said headers to said tube plates.

26. A method of assembling a tube cage for a heat exchanger of the tube and shell type which employs self-positioning baffle plates defining a plurality of apertures and includes positioning means formed as an integral part of said baffle plates and projecting from at least one side of said baffle plates, said positioning means having at least one end adapted to grippingly engage the adjacent baffle plate, the steps of the method comprising: joining a first baffle plate to a second baffle plate by grippingly engaging said positioning means of said first baffle plate to said second baffle plate such that said apertures of each baffle plate are substantially axially aligned and such that said baffle plates are alternately arranged to provide a tortuous path for a first heat exchange fluid and such that said joined baffle plAtes are restrained against either axial or rotational movement with respect to each other; connecting additional baffle plates in a like manner by grippingly engaging the positioning means of one baffle plate to said next adjacent baffle plate such that the apertures of all said baffles are substantially axially aligned and such that said baffles are alternately arranged to provide a tortuous path for a first heat exchange fluid.