GB2346959A

GB2346959A - Anti-bypass baffle

Info

Publication number: GB2346959A
Application number: GB9903352A
Authority: GB
Inventors: Robert James Gough
Original assignee: Serck Heat Transfer Ltd
Current assignee: Garrett Thermal Systems Ltd
Priority date: 1999-02-16
Filing date: 1999-02-16
Publication date: 2000-08-23
Anticipated expiration: 2019-02-16
Also published as: GB2346959B; GB9903352D0

Abstract

An anti-bypass baffle for use in a tubular heat exchanger comprises a pair of plate members (4, 5 Fig 2), each having the shape of the segment of a circle and each having a number of apertures 11 through which pass cooling tubes (6 Fig 1), and an arcuate sealing ring (3) sandwiched between the pair of plate members. The sealing ring (3) has an arcuate planar central portion and a perpendicular flange portion 7 at each end of the arcuate portion. The sealing ring (3) is resiliently compressible so that it seals between the plate members (4, 5) and the internal diameter of the tube (1) of the heat exchanger. The plate members (4, 5) are smaller than the internal diameter of the tube (1) of the heat exchanger, so they may be fitted and sealed easily without requiring machining of the internal surface of the tube.

Description

ANTI-BYPASS BAFFLE The present invention relates to the field of heat transfer and the use of heat exchangers. More particularly, the present invention is an anti-bypass baffle for use most commonly as a component within a heat exchanger.

The present invention is most commonly employed within shell and tube heat exchangers where baffles are used to direct the flow of fluid. In shell and tube heat exchangers, it is vitally important to control the movement of a fluid or gas around a circuit, with the minimum of bypass around the sealing edge of the baffles. In many known designs of heat exchanger which use baffles, bypass exists around the sealing edge of the baffle, thus having a negative impact on the potential efficiency of the heat exchanger. The reason for the bypass is most often due to the clearances that are designed into the product so as to facilitate simpler assembly, as these clearances permit bypass between the baffle and the inner wall of the heat exchanger shell.

A known technique for the reduction of bypass around baffles is to precision machine the tubestack assembly and the shell. However, this technique adds to the cost of manufacture, both in terms of time and money.

Another known technique is the use of a rubber seal around an undersized baffle plate. Again, however, this method brings with it a number of problems such as the amount of room taken up by the seal, the temperature capabilities of the rubber, and also the problem of assembling the unit.

Therefore, with the inherent problems in the known techniques, it is the aim of the present invention to provide an anti-bypass baffle which will permit easy assembly, but which will still create an effective seal between the baffle plates and the shell of the heat exchanger.

According to a first aspect of the present invention, there is provided a baffle adapted for use within a tubular housing of a heat exchange apparatus, said baffle comprising: a pair of plate members, each plate member having a plurality of apertures therein; and an arcuate sealing member situated between said pair of plate members, said sealing member being resiliently compressible between a first uncompressed state in which it has a first external dimension, and a second compressed state in which it has a second external dimension; the first external dimension of said arcuate member being greater than that of said plate members, said arcuate member being compressed for insertion within said tubular housing.

Preferably, each plate member comprises a segment of a circle bounded by a chord and an arc.

Preferably, said second external dimension is equal to an inner diameter of said tubular housing.

Preferably, said heat exchange apparatus is a shell and tube heat exchanger.

According to a second aspect of the present invention, there is provided a heat exchange apparatus, said apparatus comprising: a tubular housing; a plurality of baffles according to the first aspect of the present invention located in said housing; and a plurality of tubular members, said tubular members passing through said baffles in said housing by way of a plurality of apertures in said baffles.

According to a third aspect of the present invention, there is provided an arcuate ring member following the shape of a circle, said arcuate member having a flange at each of the two extermities of said arc, said flanges being perindicular to the plane of the circle.

Preferably, said load is a radial load. Alternatively, said load may be a transverse load.

Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a sectional view of a typical shell and tube heat exchanger; Figure 2 shows an isometric view of fluid flow around the baffle plates of a typical shell and tube heat exchanger; and Figure 3 shows an embodiment of the baffle according to the present invention.

In the typical example of Figure 1, a shell and tube heat exchanger comprises a shell 1 fitted with tubeplates 2 at each end. Within the shell 1 are a number of baffles. Each baffle contains an anti-bypass ring 3, each anti-bypass ring 3 being sandwiched between first and second baffle plates 4,5. Each baffle plate 4,5 contains a number of holes in order to accommodate a number of tubes 6, tubes 6 being located within some or all of the holes. By looking at Figure 2, the fluid flow through the heat exchanger can be seen, with the fluid flowing alternately over or under the baffles.

Figure 3 shows an embodiment of a baffle according to the present invention with the baffle in its assembled state. An anti-bypass ring 7 is sandwiched between two baffle plates 8,9. When relaxed, the ring 7 overhangs the outer diameter of the baffle plates 8,9. In order to fit this assembled tubestack into a shell, the ring 7 is compressed towards the centre of the baffle plates 8,9 so that it clears the edge of the shell. This inherent tension in the design of the ring 7 is the basis for the creation of the seal, because once the tubestack is fitted within the shell, the ring 7 provides a radial load against the inner wall of the shell, thus sealing the bypass between the baffle plates 8,9 and the shell.

The main advantage of the present invention is that it permits larger tolerances to be used between the baffles plates and the shell, while maintaining the function of either a flexible or solid baffle. After the tubestack has been assembled, it is common for it to be turned down to suit the internal diameter of the shell, which is a process which adds more cost to the finished product. However, with the present invention there is no need to machine the tubestack as the overall diameter of the baffle is smaller than the internal diameter of the shell.

Modifications and improvements may be incorporated without departing from the scope of the invention.

Claims

CLAIMS 1. A baffle adapted for use within a tubular housing of a heat exchange apparatus, said baffle comprising: a pair of plate members, each plate member having a plurality of apertures therein; and an arcuate sealing member situated between said pair of plate members, said sealing member being resiliently compressible between a first uncompressed state in which it has a first external dimension, and a second compressed state in which it has a second external dimension; the first external dimension of said arcuate member being greater than that of said plate members, said arcuate member being compressed for insertion within said tubular housing.
2. A baffle according to Claim 1, wherein each plate member comprises a segment of a circle bounded by a chord and an arc.
3. A baffle according to Claim 2, wherein the sealing member extends around the arc portion of each plate member, the sealing member include two return flange portions which project over the chord portion of one of the plate members.
4. A baffle according to any preceding Claim, wherein said second external dimension is equal to an inner diameter of said tubular housing.
5. A heat exchange apparatus, said apparatus comprising: a tubular housing; one or more baffles according to any preceding Claim located in said housing; and a plurality of tubular members, said tubular members passing through a plurality of apertures in said one or more baffles.

5. A heat exchange apparatus, said apparatus comprising: a tubular housing; one or more baffles according to any preceding Claim located in said housing; and a plurality of tubular members, said tubular members passing through a plurality of apertures in said one or more baffles.

6. A sealing ring comprising a first substantially flat planar portion having a substantially circular arc shape, said first portion having a flange portion at each of the two ends of the arc, said flanges extending out of the plane of the first portion, said sealing member being resiliently compressible between a first uncompressed state in which it has a first external diameter, and a second compressed state in which it has a second external diameter.

7. A sealing ring according to Claim 6, wherein said flanges extend perpendicular to the plane of the first portion.

8. A sealing ring according to Claim 6 or 7, wherein the first portion of the sealing ring subtends an arc of between 180 and 360 .

9. A sealing ring according to any of Claims 6 to 8, wherein the width of the first portion of the sealing ring in the plane of the sealing ring is greater than the thickness of the first portion in a direction perpendicular to the plane of the first portion.

Amenoments to the Claims have been field as follows.

1. A baffle adapted for use within a tubular housing of a heat exchange apparatus, said baffle comprising: a pair of plate members, each plate member having a plurality of apertures therein; and an arcuate sealing member situated between said pair of plate members, said sealing member being resiliently compressible between a first uncompressed state in which it has a first external dimension, and a second compressed state in which it has a second externaldimension; the first external dimension of said arcuate member being greater than that of said plate members, said arcuate member being compressed for insertion within said tubular housing.

2. A baffle according to Claim 1, wherein each plate member comprises a segment of a circle bounded by a chord and an arc.

3. A baffle according to Claim 2, wherein the sealing member extends around the arc portion of each plate member, the sealing member include two return flange portions which project over the chord portion of one of the plate members.

4. A baffle according to any preceding Claim, wherein said second external dimension is equal to an inner diameter of said tubular housing.