TRUE COUNTERCURRENT TEMA TYPE BFU SPECIAL

Abstract

A heat exchanger has a pass baffle which is formed as an enclosure with two openings, one opening for connection to a shell-side fluid opening and one opening for passing heat exchanger tubes.

Claims

1. A shell and tube heat exchanger comprising a tube bundle comprising a first and a second end secured at the first end to a tube sheet, an outer shell surrounding said tube bundle comprising at least two shell fluid connections: a shell inlet and a shell outlet, a head member affixed to said shell adjacent said tube sheet having a tube side inlet and a tube side outlet, said tube bundle comprising a longitudinally extending pass baffle comprising a first end and a second end for dividing shell side fluid into two passes between said shell inlet and shell outlet, wherein said baffle forms an enclosure comprising two openings, a first opening adapted to connection with a shell fluid connection and a second opening in the second end of the baffle for passing of the tube bundle.

2. A shell and tube heat exchanger according to claim 1, wherein said first opening is adapted to connection with the shell inlet.

3. A shell and tube heat exchanger according to claim 1, wherein said first opening is adapted to connection with the shell outlet.

4. A shell and tube heat exchanger according to claim 1, wherein said first opening is detachable connected to the shell inlet or shell outlet and is adapted to be attached or detached from the outside of the outer shell through said shell inlet or shell outlet.

5. A shell and tube heat exchanger according to claim 1, wherein said first opening is adapted to fluid tight connection with a shell fluid connection.

6. A shell and tube heat exchanger according to claim 1, wherein said baffle is fixed to said tube sheet at its first end.

7. A shell and tube heat exchanger according to claim 6, wherein the baffle is fixed to the tube sheet by means of welding.

8. A shell and tube heat exchanger according to claim 6, wherein the baffle is detachably fixed to the tube sheet.

9. A shell and tube heat exchanger according to claim 1, wherein the baffle is fluid tight fixed to the tube sheet.

10. A shell and tube heat exchanger according to claim 1, wherein said baffle is at least partly insulated to provide thermal insulation between the two passes of the shell side fluid.

11. A shell and tube heat exchanger according to claim 1, wherein said baffle has one flat side and one half circle side, forming a half moon cross sectional shape.

12. A shell and tube heat exchanger according to claim 1, wherein said tube bundle comprises a plurality of U-tubes.

13. A shell and tube heat exchanger according to claim 12, wherein said baffle is extending from the first end of the U-tubes to the inside side of the bends of the U-tubes.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0026] FIG. 1 is a horizontal cross-section of a heat exchanger according to the state of the art, and

[0027] FIG. 2 is a horizontal cross-section of a heat exchanger in accordance with the invention.

[0028] It will be understood that the drawings illustrate merely a representative embodiment of the invention and that other embodiments are contemplated within the scope of the claims.

DETAILED DESCRIPTION OF THE INVENTION

[0029] The heat exchanger shown in FIG. 1 is a two pass shell and tube unit according to the state of the art in which the tube-side fluid makes two passes through the unit and the shell-side fluid also makes two passes. The exchanger 10 includes an elongated, generally cylindrical outer shell 12 having a shell-side fluid inlet 14 and a shell-side fluid outlet 16. One end of the shell 12 is enclosed by a head 18 while the opposite end is capped with a heat exchanger head generally indicated at 20. The head 20 includes a removable cover 22, an internal stop baffle or pass partition 28, as well as a tube-side inlet 26 and a tube-side outlet 24.

[0030] The tube bundle in the exchanger of FIG. 1 comprises a plurality of U shaped tubes 32 attached at their inlet and outlet ends to a tube sheet 30. The tube sheet 30 is securely clamped about its outer periphery between the flanges on the shell 12 and the exchanger head 20. Extending horizontally between the upper and lower passes of each U tube 32 is a horizontal pass baffle indicated at 36. The pass baffle 36 is securely welded at one end to the tube sheet 30. When the head 20 of the exchanger is removed from the tube sheet 30 and the tube sheet 30 and its associated tube bundle is slidably removed from the shell 12, the pass baffle 36 may be withdrawn from the shell 12. Experience shows that there is a potential risk of leak from the inlet side of the shell to the outlet side of the shell, resulting in a part of the shell side fluid will pass the edges of the baffle 36, thus not flowing through the entire length of the shell in a true counter current relative to the tube side fluid.

[0031] In an embodiment of the invention according to FIG. 2, the pass baffle 46 is formed as an enclosure with only two openings, one opening 41 adapted to connection with a shell fluid connection, and a second opening 42 in the second end of the pass baffle 46 for passing of the tube bundle 32. There is no sealing between the shell inner side and the pass baffle, and thus no risk of any leak in such a sealing due to for instance damage or incorrect installation. In FIG. 2, the first opening of the pass baffle is connected to the shell-side fluid inlet 14, but it may be understood that the function of the heat exchanger can also be ensured if the first opening of the pass baffle is connected to the shell-side fluid outlet 16. The pass baffle may be in the cross-sectional form of a half moon, with a lower side which is substantially planar and an upper side which has a half circle cross sectional shape. To increase the thermal efficiency of the heat exchanger, at least one side of the pass baffle may be thermally insulated. The first opening of the pass baffle can be fluid tight connected to a shell fluid connection. Easy access to the shell fluid connection can be made by installing a spool piece as known in the art in connection with the shell nozzle.

[0032] Attachment or detachment of the first opening of the pass baffle may be done from the outside of the shell, through the shell-side fluid inlet or outlet which the first opening of the pass baffle is connected or is to be connected to. When shell-side fluid enters the shell, it is according to the invention forced to pass through the enclosure formed by the pass baffle when performing one of the passes through the shell and the only source of leak is the connection of the first opening of the pass baffle to the shell-side fluid inlet or outlet and not as previously known in the art, the entire length of the pass baffle.

[0033] While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the invention principals, it will be understood that the invention may be embodied otherwise without departing from said principals.