WO1996020808A1

WO1996020808A1 - Tube and shell heat exchanger and method

Info

Publication number: WO1996020808A1
Application number: PCT/US1995/017115
Authority: WO
Inventors: Rick L. Coleman
Original assignee: Coleman Rick L
Priority date: 1995-01-05
Filing date: 1995-12-29
Publication date: 1996-07-11
Also published as: AU4611696A

Abstract

A method is disclosed for producing heat exchanger tubing for use in tube and shell heat exchangers having improved heat exchange and improved fluid flow around the heat exchange tubes in which cylindrical tubing is deformed by pressure rollers to produce tubes having cylindrical ends and intermediate portions of elliptical cross section. These tubes may also be bent into U-shaped heat exchange tubes. The cylindrical end portions on one end are secured in a tube sheet (22) and the elliptical intermediate portions extend through baffle plates (24) having openings sized according to TEMA standards.

Description

TUBE AND SHELL HEAT EXCHANGER AND METHOD

HELD OF THE INVENTION This invention relates to new and useful improvements in manufacturing profiled heat exchanger tubing and assembly of tube-in-shell exchangers therefrom.

SUMMARY OF THE INVENΗON One of the objects of this invention is to provide a new and improved method for producing heat exchange tubing for use in tube and shell heat exchangers having improved heat exchange and improved fluid flow around the heat exchange tubes.

1 Another object of this invention is to provide a new and improved method for producing heat exchange tubing for use in tube and shell exchangers having improved heat exchange and improved fluid flow around the heat exchange tubes in which the heat exchange tubes have cylindrical ends and an intermediate portion deformed by pressure rollers to an elliptical cross section.

2 Another object of this invention is to provide a new and improved method for producing heat exchange tubing for use in tube and shell heat exchangers having improved heat exchange and improved fluid flow around the heat exchange tubes in which the heat exchange tubes have cylindrical ends and two intermediate portions deformed by pressure rollers to separate elliptical cross sections having their major axes displaced at a substantial angle one from the other.

3 Another object of this invention is to provide a new and improved method for producing heat exchange tubing for use in tube and shell heat exchangers having improved heat exchange and improved fluid flow around the heat exchange tubes in which the heat exchange tubes have cylindrical ends and an

1

SUBSTITUTE SHEET (RULE 26} intermediate portion deformed by pressure rollers to an elliptical cross section in which baffle plates having openings sized according to TEMA standards are supported on spacer rods, and heat exchange tubes which have cylindrical ends and an intermediate portion deformed by pressure rollers to an elliptical cross section are passed through the openings in the baffle plates so that one set of cylindrical tube ends are secured in the holes in one tube sheet and the elliptical intermediate portions are supported in the holes in the baffle plates and second tube sheet fitted over t other cylindrical ends of the tubes. 4 Another object of this invention is to provide a new and improved method fo producing heat exchange tubing for use in tube and shell exchangers having improved heat exchange and improved fluid flow around the heat exchange tube in which the heat exchange tubes have cylindrical ends and a first intermediate portion deformed by pressure rollers to a first elliptical cross section and a secon intermediate portion deformed by pressure rollers to a second elliptical cross section having its major axis at a substantial angle to the major axis of the first elliptical cross section in which baffle plates having openings sized according to TEMA standards are supported on spacer rods, and the heat exchange tubes hav cylindrical ends and a first intermediate elliptical portion passed through the openings in the baffle plates so that one set of cylindrical tube ends are secured i the holes in one tube sheet and the elliptical intermediate portions are supported in the holes in the baffle plates and a tube sheet fitted over the other cylindrical ends of the tubes. S Still another object of this invention is to provide a new and improved meth for producing heat exchange tubing for use in tube and shell heat exchangers having improved heat exchange and improved fluid flow around the heat exchange tubes in which the heat exchange tubes have cylindrical ends and an intermediate portion deformed by pressure rollers to an elliptical cross section in which baffle plates having openings sized according to TEMA standards are supported on spacer rods, and the heat exchange tubes have cylindrical ends and an intermediate elliptical portion passed through the openings in the baffle plates so that one set of cylindrical tube ends are secured in the holes in one tube sheet and the intermediate portions are supported in the holes in the plates and the assembly secured in a shell having inlet and outlet openings on the same side of the shell, the other ends of the tubes fitting into holes in a second tube sheet and the tube sheets fitted tightly on opposite ends of a heat exchange shell.

5 Still another object of this invention is to provide a new and improved method for producing heat exchange tubing for use in tube and shell heat exchangers having improved heat exchange and improved fluid flow around the heat exchange tubes in which the heat exchange tubes have cylindrical ends and an intermediate portion deformed by pressure rollers to an elliptical cross section in which baffle plates having openings sized according to TEMA standards are supported on spacer rods, and the heat exchange tubes have cylindrical ends and an intermediate elliptical portion passed through the openings in the baffle plates so that one set of cylindrical tube ends are secured in the holes in one tube sheet and the intermediate portions are supported in the holes in the baffle plates and the assembly secured in a shell having inlet and outlet openings on opposite sides of the shell, and the other ends of the tubes fitting into holes in a second tube sheet and the tube sheets fitted tightly on the opposite ends of the heat exchange shell.

6 Still another object of this invention is to provide a new and improved method for producing heat exchange tubing for use in tube and shell heat exchangers having improved heat exchange and improved fluid flow around the heat exchange tubes in which the heat exchange tubes have cylindrical ends and a first intermediate portion deformed by pressure rollers to a first elliptical cross section and second intermediate portion deformed by pressure rollers to a second elliptical cross section having its major axis at a substantial angle to the major axis of the first elliptical cross section in which baffle plates having openings sized according to TEMA standards are supported on spacer rods, and the heat exchange tubes have cylindrical ends and a first intermediate elli[tical portion passed through the openings in the baffle plates so that one set of cylindrical tube ends are secured in the holes in one tube sheet and the first elliptical intermediate portions are supported in the holes in the baffle plates and the assembly secured in a shell having inlet openings displaced angularly on the shell, and the other ends of the tubes fitting into holes in a second tube sheet and the tube sheets fitte tightly on the opposite ends of the heat exchange shell. 7 Still another object of this invention is to provide a new and improved method for producing heat exchange tubing for use in tube and shell heat exchangers having improved heat exchange and improved fluid flow around the heat exchange tubes in which the heat exchange tubes have cylindrical ends and an intermediate portion deformed by pressure rollers to an elliptical cross section in which baffle plates having openings sized to TEMA standards are supported on spacer rods, and the heat exchange tubes have cylindrical ends and an intermediate elliptical portion passed through the openings in the baffle plates so that one set of cylindrical tube ends are secured in the holes in one tube sheet an the intermediate portion are supported in the holes in the baffle plates and the assembly secured in a shell having inlet and outlet openings on the same side of the shell, the other ends of the tubes fitting into holes in a second tube sheet and the tube sheets fitted tightly on opposite ends of a heat exchange shell and headers secured over each of the tube sheets providing an inlet outlet header at one end and a fluid return header at the other end.

Still another object of this invention is provide a new and improved method fo producing heat exchange tubing for use in tube and shell heat exchangers having improved heat exchange and improved fluid flow around the heat exchange tubes in which the heat exchange tubes have cylindrical ends and an intermediate portion deformed by pressure rollers to an elliptical cross section in which baffle plates having openings sized according to TEMA standards are supported on spacer rods, and the heat exchange tubes have cylindrical ends and an intermediate elliptical portion passed through the openings in the baffle plates so that one set of cylindrical tube ends are secured in the holes in one tube sheet and the intermediate portions are supported in the holes in the baffle plates and the assembly secured in a shell having inlet and outlet openings on the same side of the shell, the other ends of the tubes fitting into holes in a second tube sheet and the tube sheets fitted tightly on opposite ends of a heat exchange shell and closure members secured over each of the tube sheets providing an inlet header at one end and an outlet at the other end. Still another object of this invention is to provide a new and improved method for producing heat exchange tubing for use in tube and shell heat exchangers having improved fluid flow around the heat exchange tubes in which the heat exchange tubes have cylindrical ends and an -intermediate portion deformed by pressure rollers to an elliptical cross section in which a firs set of baffle plates having openings sized according to TEMA standards are supported on spacer rods, and the heat exchange tubes have cylindrical ends and an intermediate portion passed through the openings in the baffle plates so that one set of cylindrical tube ends are secured in the holes in one tube sheet and the intermediate portions are supported in the holes in the baffle plates and the assembly secuted in a shell having inlet and outlet openings on opposite sides of the shell, the other ends of the tubes fitting into holes in a second tube sheet and the tube sheets fitted tightly on opposite ends of the heat exchange shell and headers secured over each of the tube sheets providing an inlet/outlet header at one end and a fluid return header at the other end. 8 Still another object of this invention is to provide a new and improved method for producing heat exchange tubing for use in tube and shell heat exchangers having improved heat exchange and improved fluid flow around the heat exchange tubes in which the heat exchange tubes have cylindrical ends and a first intermediate portion deformed by pressure rollers to a first elliptical cross section and a second intermediate portion deformed by pressure rollers to a second elliptical cross section having its major axis at a substantial angle to the major axis of the first elliptical cross section in which baffle plates having openings sized according to TEMA standards are supported on spacer rods, and the heat exchange tubes have cylindrical ends and a first intermediate elliptical portion passed through the openings in the baffle plates so that one set of cylindrical tube ends are secured in holes in one tube sheet and the first elliptical intermediate portions are supported in the holes in the baffle plates and the assembly secured in a shell having inlet and outlet openings displaced angularly on the shell, the other ends of the tubes fitting into holes in a second tube sheet and the tube sheets fitted tightly on opposite ends of the heat exchange shell and headers secured over each of the tube sheets providing an inlet outlet header at one end and a fluid return header at the other end. Other objects of the invention will become apparent from time to time throughout the specification and claims as hereinafter related.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front elevation of tube-forming rolls lor use in producing heat exchange tubing having a elliptical cross section according to a preferred embodiment of the invention .

Fig. 2 is a view in side elevation of the tube-forming rolls shown in Fig.1. Fig. 3 is a view, in elevation, of a cylindrical tube in the process of being deformed to elliptical cross section by the tube-forming rolls shown in Figs. 1 and 2. Fig. 4 is a view in elevation of a tube having cylindrical ends and an intermediate portion of elliptical cross section produced according to the process of Fig. 3.

Fig. 5 is a view in cross section taken on the line 5-5 of Fig. 4 or Fig. 7 of the cylindrical end of the tube. Fig. 6 is a view in cross section taken on the line 6-6 of Fig. 4 or Fig. 7 of the elliptical portion of the tube.

Fig. 7 is an end view of the tube shown in Fig. 4 showing the protrusion of the elliptical intermediate portion. Fig. 8 is a view in elevation of a tube having cylindrical ends and separate intermediate portions of elliptical cross section having their major axes at a substantial angle to each other produced according to the process of Fig. 3.

Fig. 9 is a view in cross section taken on the line 9-9 of Fig. 8 showing an intermediate portion of elliptical cross section having its major axis at a right angle to the major axis of the intermediate portion shown in Fig. 6.

Fig. 10 is an end view of the tube shown in Fig. 8 showing the protrusions of the elliptical intermediate portions.

Fig. 11 is a plan view of a tube sheet for receiving and securing the cylindrical ends of the heat exchange tubing. Fig. 12 is a plan view of a tube baffle plate for receiving and securing the elliptical intermediate portions of the heat exchange tubing.

Fig. 13 is a detail view of one of the tube-receiving opening or holes in the baffle plates shown in Fig. 12 for receiving the tube shown in Figs. 4-7.

Fig. 14 is a view in elevation of the tube sheet of Fig. 11 with tie rods and spacers installed.

Fig. 15 is a view in elevation of the tube sheet of the tube sheet of Fig. 11 with tie rods and spacers installed and the baffle plates of Fig. 12 positioned thereon.

Fig. 16 is a plan view of the tube sheet of Fig. 11 with tie rods and spacers installed as in Fig. 14. Fig. 17 is a plan view of the tube sheet of Fig. 11 with tie rods and spacers installed as in Fig. 14 and the baffle plates of Fig. 12 positioned as in Fig. 15.

Fig. 18 is a view in elevation in which the tube sheet, tie rods, spacers, baffle plates and tube assembly had been installed in the shell and the second tube sheet closes the other end of the tube, where the inlet outlet openings are on the same side.

Fig. 19 shows a further step in the assembly of the tubing into a shell in which the assembly shown in Fig. 18 has headers positioned and secured on oppsite ends.

Fig.20 shows another embodiment in which the tube sheet tie rods, spacers and baffle plates and tube assembly has been installed in tube shell and the second tube sheet closes the other end of the shell, where the shell has inlet and outlet openings spaced angularly apart. Fig. 21 shows a further step in the assembly of the tubing into a shell in which the assembly shown in Fig. 20 has headers positioned and secured on opposite ends.

Fig. 22 shows a further step in the assembly of the tubing into a shell for a condenser in which the assembly has headers positioned and secured on opposite ends and the shell has gas inlet and hquid outlet openings on upper and lower sides thereof.

Fig. 23 is a cross section of one of the heat exchange tubes taken on the line 23-23 of Fig. 22.

Fig. 24 is a view in elevation of one of the baffle plates in the embodiment of Fig. 22.

Fig. 25 is a view in elevation of a tube having cylindrical ends, and separate intermediate portions of elliptical cross section having aligned major axes and a mid portion of cylindrical shape of the same size as the ends.

Fig. 26 is a view in elevation of the tube shown in Fig. 25 bent 180deg at the mid portion to form a U-shaped heat exchange tube.

Fig. 27 is a view in elevation of an assembled tube and shell heat exchanger having an inlet at one end of the shell and an outlet at the other end.

SUBSTITUTE S &HEET (RULE 26) Fig. 28 shows an alternate method of construction where a short section of shell is used and the remainder of the shell welded thereon at a subsequent step in the assembly.

Fig. 29 shows an alternate method of construction where a short section of shell is used as in Fig. 28 and showing the connection to one of the tube sheets. DESCRIPTION OF ONE PREFERRED EMBODIMENT This invention relates to new and useful improvements in methods and apparatus for producing heat exchange tubes having a profile producing a higher surface area to internal flow ratio for improved efficiency in tube and shell heat exchangers and in improved tube and shell heat exchangers produced therefrom. The method involves deforming a cylindrical heat exchange tube in an intermediate portion to produce a tube having cylindrical ( circular cross section) ends and an elliptical cross section mid portion. The tubes are assembled with supporting tube sheets at both ends and baffle plates along the elliptical mid- portions and placed in a shell having dished end headers.

In Figs. 1 and 2, there are shown front and side elevations of forming rolls 1 and 11 supported on vertically extending and vertically/reciprocally movable support members 12 and 13. Rolls 10 and 11 have curved surfaces 14 and 15 which are engageable with a tube for deforming its shape as required herein. In the first step of this method, a tube 16 of a suitable heat exchange material such as steel, stainless steel, copper, copper alloys, bronze, brass, aluminum or plastic, having an initial cylindrical shape (circular cross section) is contacted by rolls 10 and 11 under pressure to deform the tubing to a form having cylindrical ends (circular cross section) 17 and 18 and an elliptical cross section intermediate portion 19. In carrying out this step, rollers 10 and 11 are contacted with the tube under pressure to deform the intermediate portion 19 to an elliptical cross section (see Figs. 6 and 7) and moved relative to the tube (or the tube drawn or pushed through the rollers) and separated just short of the other end of the tube to produce the tube 16 of Fig. 4 having cylindrical (circular) ends 17 and 18 and an elliptical cross section intermediate portion 19. As used throughout this specification and claims, the term "moving the rollers relative to the tube" is defined to mean moving the rollers along the tube or drawing or pushing the tube through the rollers or operating the rollers under power to draw the tube through the rollers, This procedure may be carried out adjacent to the place of assembly of the heat exchanger or may be carried out at another location where the finished tubes may be stored and subsequently released for use in the assembly.

In an alternate embodiment of the tube formation (see Fig.8), tube 16a is deformed for part of its length, e.g., about three-fourths the length, the deforming rolls 10 and 11 then compressed to produce a second intermediate portion of elliptical cross section displaced at a substantial angle from the first intermediate portion with a (circular) cylindrical portion 20 (Fig. 8) between the elliptical portions. The rotation or displacement of one elliptical portion relative to the other may be any selected angular amount depending on the desired angular separation of the inlet and outlet on the tube shell described below. The size of the angle depends on the installation, lrie angle permits the assembly to be located where the inlet comes in on one side and the outlet is angularly displaced to position the outlet away from walls or other obstructions. Fig.8 illustrates the product obtained, i.e., tube 16a, which has cylindrical ends 17 and 18 and a cylindrical central portion 20 and elhptical intermediate portions 19 and 21 (Figs. 8-10) having their major axes offset 90deg from each other.

The tubes produced as shown in Figs. 4 and 8 are used in the assembly of a tube and shell heat exchanger as described below. The spacing of tubes in the heat exchange shell is in accordance with TEMA (Tubular Exchanger Manufacturers Association) mechanical standards Class RCB. Tubes may be assembled in triangular, rotated triangular, square or rotated square pattern as illustrated in the Standards of the Tubular Exchanger Manufacuters Association . Minimum spacing, i.e., minimum center to center distance, is generally 1.25 times the O.D. of the tubes. A circular tube sheet 22 has circular holes or apertures 23 sized to receive the cylindrical ends 17 or 18 of tubes 16 and holes or apertures 23a sized to support tie rods and spacer members as described below. A circular disk-shaped baffle plate 24, having a O.D. which is smaller than the tube plate 22 by at least the wall thickness of the heat exchange shell, has an flat edge 25 cut or formed along a chord of the disk. Baffle plates 24 have holes or apertures 26 shaped to allow tubes 16 to pass through and holes or apertures 26a having the same size as holes 23a in tube sheet 22. An enlarged detail of hole 26 is shown in Fig. 13 having a shape configured to pass the embodiment of tube 16 shown in Figs. 4 and 7. Circular portions 27 of hole 26a are shaped to pass the circular portion 17, 1 and elliptical portions 28 are shaped to pass elliptical portions 19 of tube 16 shown in Fig. 4 and 7.

The first assembly step is shown in Fig. 14. Two or more tie rids 29 are positioned in openings 23a in a first tube sheet (Figs. 14 and 16) and are shorter than the tubes that are to be installed. Tie rods 29 are preferable threaded on each end to permit on end to be threaded into the first tube sheet 22 and the other end to have a nut threaded thereon to secure the tube bundle together. A first spacer tube 29a is fitted over each of the tie rods 29 to set the position of the first baffle plate 24. Next, the one of the baffle plates 24 is positioned on tube 29a which aligns spacer tube holes 26 with the holes 23 in tube sheet 22. Next, another set of spacer tubes 29a are positioned on tie rods 29 abutting the first baffle plate 24 and setting the distance to the next baffle plate 24. A second of the baffle plates 24 is then positioned with its holes 26a over tie rids 29 in a reversed position and the assembly continued in the same manner for as many baffle plates as are desired or needed, with successive baffle plates 24 having their flat edges 25 alternating (Fig. 15), i.e., 180deg apart. I^*his procedure can be continued for as many baffle plates as are required in the heat exchange assembly. In this case only three baffle plates 24 are used for ease of illustration. After the last of the baffle plates 24 are installed, nut 29b is screwed on the upper end of tie rod 29 and tightened to lock the tube sheet, tie rods, spacers and baffle plates together as tube assembly. The ends of tubes 16 are successively fe through the aligned holes 26 until the one cylindrical end 1 of each tube is inserted into the aligned hole 23 in the first tube sheet 22. This is repeated until tubes have been inserted through all of the holes 26 in the baffle plates 24 and th lower (as viewed in Fig. 18) ends fill all of holes 23 in the lower tube sheet 22. Then the assembly with the tubes installed is placed inside a heat exchange shell 30 (of appropriate material, e.g., steel, stainless steel, aluminum or copper o copper alloys, bronze, brass or plastic) with the other ends of tubes 16 exposed and shell 30 abutting the lower tube plate 22. The alignment of the baffle plates 24 is such that their circular edges fit the inner surface (l.D.) of shell 30 as tightly as possible while allowing for assembly. A second or upper tube sheet 22 is positioned with its holes 23 over the upper ends of tubes 16 and abutting the upper end of shell 30. The upper cylindrical (circular) portions are secured (e.g., rolled, welded, soldered or brazed) in holes 23. Upper and lower tube sheets 22 are secured (e.g., by welding, soldering or brazing) to ends of shell 30.

Dished headers 31 and 32 (Fig. 19) are secured (by nuts and bolts, welding, soldering or brazing) to the upper and lower tube plates 22. Headers 31 and 32 may also be secured by typical flanged connection using bolts through aligned holes in the periphery of plates 22 and headers 31 and 32 with suitable gaskets between the tube plates and headers, lliis construction is not shown but is conventional in tube and shell heat exchangers. Header 31 has an inlet tube 37 (Fig.19) on the same side. In the operation of this embodiment, one fluid (liquid or gas) enters through inlet 33 and flows through the tubes 16 opening from the inlet side of wall 35 to the chamber formed by return header 32 and returns through the tubes 16 opening into the outlet side of wall 35 and out through outle 34. The other fluid (gas or hquid) enters through inlet tube 36, flows circuitously

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SUBSTITUTE SHEET (RULE 2C) around baffle plates 24 and exits through outlet 37 on the same side of the shell 30.

ANOTHER EMBODIMENT In another embodiment, tubes 16 are used to produce the heat exchange assembly shown in Figs. 20 and 21. A modified procedure is followed. llie first assembly step is shown in Fig. 14. At least two tie rods 29 are positioned in openings 23a in a first tube sheet (Figs. 14 and 16) and are shorter than the tubes that are to be installed. Tie rods 29 are preferable threaded on each end to be threaded into the first tube sheet 22 and the other end to have a nut threaded thereon to secure the tube bundle together. A first spacer tube 29a is fitted over each of the tie rods 29 to set the position of the first baffle plate 24. Next, the one of the baffle plates 24 is positioned on spacer tube 29a which aligns tube holes 26 with the holes 23 in tube sheet 22. Next, another set of spacer tubes 29a are positioned on tie rods 29 abutting the first baffle plate 24 and setting the distance to the next baffle plate 24. A second one of the baffle plates 24 is then positioned with its holes 26a over tie rods 29 in a reversed position and the assembly continued in the same manner for as many baffle plates as are desired or needed, with successive baffle plates 24 having their flat edges 25 alternating (Fig.15), i.e., 180deg apart. This procedure can be continued for as many baffle plates as are required in the heat exchange assembly, in this case only three baffle plates 24 are used for ease of illustration. The last of the baffle plates 24, however, has its edge 25 displaced to cause flow over the angularly displaced elhptical portion toward the angularly displaced outlet. After the last of the baffle plates 24 is installed, nut 29b is screwed on the upper end of tie rod 29 and tightened to lock the tube sheet, tie rods, spacers and baffle plates together as a tube assembly.

In this embodiment, the tubes 16 of Fig. 8 are used. The ends of tubes 16a are successively fed through the aligned holes 26 until the cylindrical end 17, below elliptical portion 21, of each tube is inserted into the aligned hole 23 in the first tube sheet 22. This is repeated until tubes have been inserted through all of the holes 26 in the baffle plates 24 and the lower ( as viewed in Fig. 18) ends fill all of the holes 23 in lower tube sheet 22. Then assembly with the tubes 16a installed is placed inside a heat exchange shell 30 (of appropriate material, e.g., steel, stainless steel, aluminum or copper or copper alloys, bronze, brass or plastic) with the other ends of tubes 16 exposed and shell 30 abutting the lower tube plate 22. the alignment of the baffle plates 24 is such that their circular edges fit the inner surface (l.D.) of shell 30 as tight as possible while allowing for assembly. A second or upper tube sheet 22 is positioned with its holes 23 over the upper ends of tubes 16 and abutting the upper end of shell 30 and the lower and upper cylindrical (circular) portions secured (e.g., rolled, welded, soldered or brazed) in holes 23. Upper and lower tube sheets 22 are secured (e.g., welding, soldering or brazing) to the ends of shell 30.

Closure members, e.g., dished headers 31 and 32 (Fig.21) are then secured (b nuts and bolts, welding, soldering or brazing) to the upper and lower tube plates 22. Headers 31 and 32 may also be secured by a typical flanged connection usin bolts through aligned holes in the periphery of plates 22 and headers 31 and 32 with suitable gaskets between the tube plates and headers. 1 ^"his construction is not shown but is conventional in tube and shell heat exchangers. Headers 31 has an inlet tube 33 and outlet tube 34 and internal wall 35. Shell 30a has an inlet tube 36a and outlet tube 37a (Figs. 20 and 21 ) spaced 90deg (or other suitable angle) apart around the circumference of the shell which are aligned with the major axes of the elliptical portions 19 and 21, respectively. In the operation of this embodiment, one fluid (hquid or gas) enters through inlet 33 and flows through the tubes 16 opening from the inlet side of wall 35 to the chamber forme by return header 32 and returns through the tubes 16 opening into the outlet side of wall 35 and out through outlet 34. The other fluid (gas or liquid) enters through inlet tube 36a, flows circuitously around baffle plates 24 and exits

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SUBSTITUTE SHEET (RULE 26Ϊ through outlet tube 37a at a point 90deg (or other suitable angle) from inlet tube 36a on the shell 30.

A FURTHER EMBODIMENT A further embodiment (vapor condenser or separator) is shown in Fig. 22-24. This embodiment differs from the embodiment of Figs. 18 and 19 in that a modified baffle plate is used (Fig.24) and the inlet and outlet tubes to the shell are on opposite sides of the shell (Fig. 22).

A circular tube plate 22 has circular holes or apertures 23 sized to receive the cylindrical ends 17 or 18 of tubes 16 and holes or apertures 23a sized to receive tie rods as described below. A circular disk-shaped baffle plate 24a, having a

O.D. smaller than tube plate 22 by at least the wall thickness of the heat exchange shell, has flat edges 25 and 25a cut or formed along a chord of the disk on opposite sides thereof. Baffle plates 24a have holes or apertures 26 shaped to allow tubes 16 to pass through and holes or apertures 26a having the same size as holes 23a in tube sheet 22. An enlarged detail of hole 26 is shown in Fig. 13 having a shape configured to pass the embodiment of tube 16 shown in Figs. 4,7 and 23. Circular portions 27 of hole 26a are shaped to pass the circular portion 17,18 and elliptical portions 28 are shaped to pass elhptical portions 19 of tube 16 shown in Figs. 4, 7 and 23. llie first assembly step is shown in Fig. 14. At least two tie rods 29 are positioned in openings 23a in a first tube sheet (Figs. 14 and 16) and are shorter than tubes that are to be installed, lie rods 29 are preferable threaded on each end to permit one end to be threaded into the first tube sheet 22 and the other end to have a nut threaded thereon to secure the tube bundle together. A first spacer tube 29a is fitted over each of the tie rods 29 to set the position of the first baffle plate 24. Next, the one of the baffle plates 24 is positioned on tube spacer 29a which aligns tube holes 26 with the holes 23 in tube sheet 22. Next, another set of spacer tubes 29a are positioned on tie rods 29 abutting the first baffle plate 24 and setting the distance to the next baffle plate 24. A second one of the baffle

SUBSTITU J1T&E SHEET (RULE 26) plates 24 is then positioned with its holes 26a over tie rods 29 in alignment with the first baffle plate and assembly continued in the same manner for as many baffle plates as are desired or needed, with successive baffle plates 24 having the flat edges 25 aligned. This procedure can be continued for as many baffle plates as are required in the heat exchange assembly. In this case only four baffle plate 24a are used for ease of illustration.

After the last of the baffle plates 24a is installed, nut 29b is screwed on the upper end of tie rod 29 and tightened to lock the tube sheet, tie rods, spacers and baffle plates together as an assembly. The ends of tubes 16 are successively fed through the aligned holes 26 until the one cylindrical end 1 of each tube is inserted into the aligned hole 23 in the first tube sheet 22. This is repeated until tubes have been inserted through all of the holes 26 in the baffle plates 24 and th lower (as viewed in Fig. 18) ends fill all of the holes 23 in the lower tube sheet 2 Then the assembly with the tubes installed is placed inside a heat exchange shell 30b (of appropriate material, e.g., steel, stainless steel, aluminum or copper or copper alloys, bronze, brass or plastic) with the other ends of tubes 16 expose and shell 30 abutting the lower tube plate 22. The alignment of the baffle plates 24 is such that their circular edges fit the inner surface (l.D.) of shell 30 as tight as possible while allowing for assembly. A second or upper tube sheet 22 is positioned with its holes 23 over the upper ends of tubes 16 and abutting the upper end of shell 30b and the lower and upper cylindrical (circular) portions secured (e.g., rolled, welded, soldered or brazed) in holes 23. Upper and lower tube sheets 22 are secured (e.g., welding, soldering or brasing) to ends of shell 30b. Closure members, e.g., dished headers 31 and 32 (Fig.22), are then secured

(by nuts and bolts, welding, soldering or brazing) to the upper and lower tube plates 22. headers 31 and 32 may also be secured by a typical flanged connectio using bolts through aligned holes in the periphery of plates 22 and headers 31 an 32 with suitable gaskets between the tube plates and headers. This construction is not shown but is conventional in tube and shell heat exchangers.

Header 31 has an inlet tube 33 and outlet tube 34 and internal wall 35. Shell 30b has an inlet tube 36b at the top and outlet tube 37b at the bottom (Fig. 22). In the operation of this embodiment, cooling fluid (liquid or gas) enters through inlet 33 and flows through the tubes 16 opening from the inlet side of wall 35 to the chamber formed by return header 32 and returns through the tubes 16 opening into the outlet side of wall 35 and out through outlet 34. A gas (vapor) enters through inlet tube 36b spreads across the top of shell 30b and flows around baffle plates 24 through the bank of tubes 16, condensing to a liquid which exits through outlet tube 37b on the bottom of the sell 30b.

ANOTHER EMBODIMENT In Figs. 25 and 26, there is shown a further embodiment of the invention as applied to U-tubes for use in tube and shell heat exchangers. In an alternate embodiment of tube formation (see Fig. 25), tube 16b is deformed for part of its length, e.g., about one half the length, the deforming rolls 10 and 11 then compressed to produce a second intermediate portion of elliptical cross section aligned with the first intermediate portion. Fig.25 illustrates the product, tube 16b, thus obtained, which has cylindrical ends 17 and 18 and a cylindrical central portion 20a and elliptical intermediate portions 19 and 21 having their major axes aligned with each other. In the next step, the tube 16b is bent 1 0deg at 20a so that the elhptical portions 19 and 21 are parallel and ends 17 and 18 are closely spaced.

In this embodiment, only one tube sheet is used. A circular tube sheet 22 has circular holes or apertures 23 sized to receive the cylindrical ends 17 or 18 of tubes 16 and holes or apertures 23a sized to support tie rods and spacer members as described below. A circular disk-shaped baffle plate 24, having O.D. which is smaller than the tube plate 22 by at least the wall thickness of the heat exchange shell, has an flat edge 25 cut or formed along a chord of the disk. Baffle plates 24 have holes or apertures 26 shaped to allow tubes 16 to pass through and holes or apertures 26 having the same size as holes 23a in tube sheet 22. An enlarged detail of hole 26 is shown in Fig 13 having a shape configured to pass the embodiment of tube 16 shown in Figs. 4 and 7. Circular portions 27 of hole 26a are shaped to pass the circular portion 17, 18 and elliptical portions 28 are shape to pass elliptical portions 19 of tube 16 shown in Figs. 4 and 7.

The first assembly step is shown in Fig. 14. Two or more tie rods 29 are positioned in openings 23a in a first tube sheet (Figs. 14 and 16) and are shorter than the tubes that are to be installed. Tie rods 29 are preferable threaded on each end to permit one end to be threaded into the first tube sheet 22 and the other end to have a nit threaded there on to secure the tube bundle together. A first spacer tube 29a is fitted over each of the tie rods 29 to set the position of the first baffle plate 24. Next, the one of the baffle plates 24 is positioned on spacer tube 29a which aligns tube 26 with the holes 23 in tube sheet 22. Next, another set of spacer tubes 29a are positioned on tie rods 29 abutting the first baffle plate 24 and setting the distance to the next baffle plate 24. A second one of the baffle plates 24 is then positioned with its holes 26a over tie rods 29 in a reversed position and the assembly continued in the same manner for as many baffle plate as are desired or needed, with successive baffle plates 24 having their flat edges 25 alternating (Fig. 15), i.e., 180deg apart. This procedure can be continued for as many baffle plates as are required in the heat exchange assembly. In this case only three baffle plates 24 are used for ease of illustration.

After the last of the baffle plates 24 is installed, nut 29b is screwed on the upper end of tie rod 29 and tightened to lock the tube sheet, tie rods, spacers and baffle plates together as an assembly. The ends 17 and 18 of U-tubes 16b are successively fed through the aligned holes 26 until the one cylindrical end 1 of each tube is inserted into the aligned hole 23 in the first tube sheet 22. This is repeated until U-tubes have been inserted through all of the holes 26 in the baffle plates 24 and the lower (as viewed in Fig. 18) ends fill all of the holes 23 in the lower tube sheet 22. Tubes 16b are secured (e.g., by rolling, welding, soldering or brazing) in holes 23 of tube sheet 22.

After the all the tubes 16b are secured (e.g., rolled, welded, soldered or brazed) in place in holes 23 in the single tube sheet 22, the tube bundle, including the installed tubes 16, is placed inside a heat exchange shell 30 (of appropriate material, e.g., steel, stainless steel, aluminum or copper or copper alloys, bronze, brass or plastic) with the other ends of tubes 16 exposed and shell 30 abutting the lower tube plate 22. The alignment of the baffle plates 24 is such that their circular edges fit the inner surface (I.D.) of shell 30 as tight as possible while allowing for assembly. The upper, rebent end portions 20a of tubes 16 a are not covered by a tube sheet as in other embodiments. The one tube sheet is secured (e.g., by rolling, welding, soldering or brazing) to one end of shell 30. Suitable headers of any appropriate design may be installed on opposite ends of shell 30.

A FURTHER EMBODIMEN T Fig. 27 illustrates a further embodiment of the invention in which the inlet and outlet to the heat exchanger tubes are on opposite ends of the tube and shell heat exchanger. In this embodiment, headers 31 and 32 have inlet 31 and outlet 32 on opposite ends of the shell 30 (or 30a or 30b). 'This embodiment allows the tubes 16 to have through flow rather than a reverse flow at one end of the shell. A FURTHER EMBODIMEN T

Fig. 28 and 29 illustrate a further embodiment of the invention in which the shell is assembled in sections. A short section of sell 130 (Fig 28) has one of the outlet of inlet openings 36, 37 therein. This section 130 is then secured (e.g., welding, soldering or brazing) to tube sheet 22 and the tie rods, spacer tubes and baffle plates installed as previously described. A similar short shell section is secured to the other tube sheet for use at the other end of the assembly. Then, after the heat exchange tubes are secured in place, the main length of shell 30 is secured (e.g., welding, soldering or brazing) to short section 130 and the other short section 130 and second tube sheet 22 are installed with the tubes in the tube sheet holes and the short section 130 secured (e.g., welding, soldering or brazing) to the other end of the main shell section.

While this invention has been described fully and completely with special emphasis on certain preferred embodiments, it should be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

Claims

CLAIMS:

1. A method of producing heat exchangers having improved flow and heat exchange properties which comprises: providing a hollow cylindrical tube, deforming a predetermined length of an intermediate portion of said tube into a substantially elliptical cross section without deforming the ends of the tube from their cylindrical shape, providing at least one tube sheet having a predetermined number of holes having a diameter substantially the same as the O.D of said tube cylindrical ends, and securing said tube cylindrical ends in said tube sheet holes.

2. A method according to claim 1 including providing a pair of reciprocally movable compression rollers, moving said rollers together against said tube at a point spaced from the end of the tube and linearly along said tube to compress and deform the tube to produce said elliptical cross section and moving said rollers away from said tube after forming said elliptical cross section.

3. A method according to claim 2 in which said rollers are moved together against and linearly along one portion of said tube, moved away from said tube, and then moved together against and linearly along another portion of said tube, to produce linearly spaced portions of elliptical cross section, and finally moved away from said tube.

4. A method according to claim 3 further including bending said intermediate portion 180deg to produce a U-shaped tube having adjacently positioned cylindrical ends.

5. A method according to claim 3 including rotating said tube for a predetermined angle after said rollers are moved away from said tube and before being moved together against said another portion of said tube, to produce angularly offset linearly spaced elliptical cross sections separated by an intermediate portion of cylindrical cross section.

6. A method according to claim 1 which two tube sheets are provided, and opposite cylindrical ends of said tubes are secured in both tube sheets.

7. A method according to claim 4 in which only one tube sheet is provided , and said adjacently positioned cylindrical ends are secured in said tube sheet.

8. A method according to claim 1 further including providing baffle plates having holes sized and shaped to just pass the cylindrical ends and elhptical cross section portions of said tubes having the same spacing as the holes in said tube sheet, supporting said baffle plates in spaced relations with said baffle plate holes aligned with said tube sheet holes, and inserting said tubes through said baffle plate holes and then securing said tube cylindrical ends in said tube sheet holes with said elliptical cross section tube portions being supported in said baffle plates.

9. A method according to claim 8 in which supporting said baffle plates in spaced relation includes providing tie rods and spacer members, securing said tie rods in said tube sheet, placing a first set of spacer members over said tie rods, placing the first of said baffle plates over said tie rods abutting said first set of spacer members, repeat placing baffle plates and spacer members a predetermined number of times, and providing securing members and placing them on said tie rods to engage and lock said baffle plates in fixed relation as a heat exchange tube assembly.

10. A method according to claim 1 further including providing baffle plates having holes sized and shaped to just pass the cylindrical ends and elliptical cross section portions of said tubes having the same spacing as the holes in said tube sheet, providing tie rods and spacer members, securing said tie rods in said tube sheet, placing a first set of spacer members over said tie rods, placing the first of said baffle plates over said tie rods abutting said first set of spacer members, repeat placing baffle plates and spacer members a predetermined number of times, providing securing members and placing them on said tie rods to engage and lock said baffle plates in fixed relation as a heat exchange tube assembly, inserting said tubes through said baffle plate holes and then securing said tube cylindrical ends in said tube sheet holes with said elliptical cross section tube portions being supported in said baffle plates, providing a hollow heat exchange shell having an inlet and an outlet through the wall thereof, placing said shell over said heat exchange tube assembly, and securing one end of said shell to said tube sheet.

11. A method according to claim 10 including providing a second tube sheet having holes sized to receive the ends, placing said second tube sheet over the unsecured ends and abutting the end o said shell, and securing said second tube sheet and the unsecured ends of said tubes to said shell.

12. A method according to claim 1 in which said shell comprises at least short portion and a long portion, said tube sheet is secured to said short shell portion, and then said long shell portion is secured to said short shell portion.

13. A method according to claim 11 in which said shell comprises two short portions and long portion, one tube sheet is secured to one short shell portion, the other tube sheet is secured to the other short portion, and then said long shell portion is secured to said short shell portions.

14. A method according to claim 10 including providing header members and securing one to each end of said shell, at least on of said headers having an inlet opening and at least one of said headers having an outlet opening.

15. Method according to claim 7 in which only one tube sheet is provided, and further including providing baffle plates having holes sized and shaped to just pass the cyhndrical ends and elliptical cross section portions of said tubes having the sam spacing as the holes in said tube sheet, supporting said baffle plates in spaced relation with said baffle plate holes aligned with said tube sheet holes, and inserting said tubes through said baffle plate holes and then securing said tube adjacently positioned cylindrical ends in said tube sheet holes with said elliptical cross section tube portions being supported in said baffle plates.

16. A method according to claim 15 including providing a hollow heat exchange shell having an inlet and an outlet through the wall thereof placing said shell over said heat exchange tube assembly, securing one end of said shell and said tubes to said tube sheet, and providing end closure members and securing one to each end of said shell.

17. A method according to claim 5 further including providing baffle plates having holes sized and shaped to just pass the cylindrical ends and elhptical cross section portions of said tubes having the same spacing as the holes in said tube sheet, supporting said baffle plates in spaced relation with said baffle plate holes aligned with said tube sheet holes, and inserting said tubes through said baffle plate holes and then securing said tube cylindrical ends in said tube sheets holes with said elliptical cross section tube portions being supported in said baffle plates.

18. A method according to claim 17 in which supporting said baffle plates in spaced relation includes providing tie rods and spacer members, securing said tie rods in said tube sheet, placing a first set of spacer members over said tie rods, placing the first of said baffle plates over said tie rods abutting said first set o spacer members, repeat placing baffle plates and spacer members a predetermined number of times, providing securing members and placing them on said tie rods to engage and lock said baffle plates in fixed relation as a heat exchange tube assembly, and inserting said tubes through said baffle plates holes and then securing said tube cyhndrical ends in said tube sheet holes with said first elhptical cross sectio tube portions being supported in said baffle plates.

19. A method according to claim 18 including providing a hollow heat exchange shell having an inlet and an outlet through the wall thereof angularly spaced at substantially the same angular spacing as said elliptical portions, placing said shell over said heat exchange tube assembly, and securing one end of said shell and the ends of said tubes to said tube sheet.

20. A method according to claim 1 including providing a second tube sheet having holes sized and spaced to receive the ends, placing said second tube sheet over the unsecured ends of said tubes and securing them therein, securing said second tube sheet and the other ends of said tubes to said shell, and providing header members and securing one to each end of said shell.

21. A heat exchanger assembly having improved flow and heat exchange properties which comprises:

26 SUBSTITUTE SHEET (RULE 2P> a plurality of hollow cylindrical tubes each having a predetermined length of an intermediate portion thereof deformed into a substantially elhptical cross section and having undeformed cyhndrical ends, at least one tube sheet having a predetermined number of holes having a diameter substantially the same as the O.D. of said tube cylindrical ends, and one tube cylindrical end of each tube being secured in said tube sheet holes.

22. A heat exchanger assembly according to claim 21 including said baffle plates having holes on the same size and spacing as said tube plate holes and supported in spaced relation on tie rods and spacer members secured in said tube sheet, securing members on said tie rods engaging and locking said baffle plates in fixed relation as a heat exchange tube assembly, and said tubes extending through said baffle plates holes with said tube cyhndrical ends secured in said tube sheet holes with said elliptical cross section tube portions supported in said baffle plate holes.

23. A heat exchanger assembly according to claim 21 in which each of said tubes has linearly spaced elliptical cross sections with an intermediate portion of cyhndrical cross section therebetween.

24. A heat exchanger assembly according to claim 23 in which said intermediate portion is bent 180deg so that said tube has U-shape with adjacently positioned cylindrical ends positioned in said tube sheet.

25. A heat exchanger assembly according to claim 23 in which said hnearly spaced elliptical cross sections have their major axes at a substantial angle to each other and separated by an intermediate portion of cylindrical cross section.

27 SUBSTITUTE SHEET (RULE *6,

26. A heat exchanger assembly according to claim 21 including a hollow heat exchange shell having an inlet and an outlet through the wall thereof in which the heat exchanger assembly is positioned.

27. A heat exchanger assembly according to claim 26 including header members secured one to each end of said shell.

28. A heat exchanger assembly according to claim 27 in which one header member has an inlet opening and the other header member has an outlet opening.

29. A heat exchanger assembly according to claim 27 in which one header member has an inlet opening and an outlet opening and a wall therebetween.