US1848741A

US1848741A - Heat exchanger baffle construction

Info

Publication number: US1848741A
Authority: US
Publication date: 1932-03-08
Anticipated expiration: 1949-03-08

Description

March 8, 1932. E. H. NELSON HEAT EXCHANGER BAFFLE CONSTRUCTION Filed Dec. 1, 1930 IVENTOR ATTORNEYS cure a tight joint between I cause of the lack of uniformity of the shells,

Patented Mar. 8, 1932 UNITED STATES PATENT OFFICE ERIC H. NELSON, 0F MASSILLON, OHIO, ASSIGNOR TO THE GRISCOM-RUSSELL COMPANY,

' 01E NEW YORK, N. Y., A. CORPORATION OF DEA-WARE HEAT EXCHANGER BAFFLE CONSTRUCTION i Application filed December 1, 1930. Serial No. 499,280,

This invention relates to heat exchangers and more particularly concerns an improved tube and shell type heat exchanger.

One well known type of heat exchanger which is employed to effect the transfer of heat between two fluids of difl'erenttemperatures comprises generally a shell or drum having a plurality of tubes passing therethrough and fixed to tube sheets which close the-endsiof the shell. One of the fluids between which an exchange of heat is desired is passed through the tubes and the other fluid is passed through the shell in contact with the exterior surfaces of the tubes, heat being transferred from one fluid to the other through the tube walls.

In order to insure efficient operation it is often necessary to provide baffles, or other means, restricting the path of flow through the apparatus, whereby relatively high velocity of the fluid is maintained. Accordingly it is desirable to employ one or more longitudinally extending baflies within the shell, these bafiies being disposed between groups or'bundles of the tubes and acting to direct the fluid passing through the shell back and forth longitudinally of the shell along the tube surfaces. Where bafiles are employed to insure relatively high velocity of the fluid passing through the shell the pressure within the shell near the inlet maybe considerably higher than the pressure near the outlet and unless the baflles are properly sealed along their edges there is a tendency for the fluid to by-pass around the edges of the baflles, thus impairing to some extent the function of the bafiles. Where this occurs, the velocity of the fluid passing through the shell is reduced and some of the fluid fails to travel the entire path through the apparatus and accordingly there is inefficient. heat exchange.

-Heret0fore efforts have been made to sethe baffle and the shell by boring the shell, or by machining grooves along the inside of the shell and in- Where this connect1on between the baflle plate and the sert ing bafiies in the grooves. is attempted difliculties are encountered beand the'boring operation is very expensive. Expensive equipment is required and much obtained between the bafiie plate and the shell wall. A further object of the invention resides in the provision of a heat exchanger Furthermore it is necessary to perof the type described which is simple in construction and inexpensive to manufacture and assemble.

In general, the above and other objects of the invention are carried out by employing one or more baflie plates, the edges of which are welded or otherwise suitably secured Within spaced longitudinal slots or openings extending completely through the wall of the heat exchanger shell. In accordance with the invention, parallel slots are preferably cut .through the shell at intervals and the bafiie plate is inserted therethrough, the edges of the plate resting Within and at least partially filling the slots, after which the edges of the baflie plates are sealed to the shell and the slots are closed by welding or equivalent means.

The invention will be best understood by reference to the accompanying drawings, in

which certain embodiments thereof have been illustrated. In the drawings;

Figure 1 is a sectional elevation of a heat exchanger embodying the invention; Fig. 2 is a sectional end View of the heatexchanger of Fig. 1;

Fig. 3 is an enlarged sectional view of the Fig. 4 is a cross-sectional view of a modified form of heat exchanger shell having two baflle plates mounted therein;

Fig. 5 is a sectional elevation on a reduced scale of the heat exchanger shown in Fig. 4;

Fig. 6 is a cross-sectional View of a modified form of heat exchanger having three baflle plates therein; and

Fig. 7 is a sectional elevation on a reduced scale of the heat exchanger shown in Fig. 6.

Referring to the drawings, and more particularly to Figs. 1, 2 and 3, the heat exchanger illustrated comprises generally a cylindrical shell 1, the opposite ends of which are closed by the tube sheets 2 and 3 which may be fixed to the shell in any suitable manner. A plurality of tubes T generally divided into two groups 4 and 5 are sealed at their opposite ends Within openings in the tube sheets 2 and 3. Suitable heads 6 and 7 are respectively fixed to the outer surfaces of the tube sheets 2 and 3, and the outer ends of these heads are respectively closed by the caps 8 and 9. The heads 6 and 7 are respectively provided with fluid ports 10 and 11, and one of the fluids passed through the exchanger may be admitted through the port '11 and passed through the interior of the head 7, and tubes T and the interior of the head 6, flowing out through the port 10.

The fluid which is passed over the exterior surfaces of the tubes T may be admitted to the interior of the shell 1 through the port 12 and withdrawn therefrom through the port 13. Since the heat exchanger shown in Figs. 1 and 2 is of the double-pass type,the

ports

12 and 13 are both located at the same end of the shell.

In order that the fluid passin within the shell 1 may flow along the surfaces of the tubes T throughout their entire length in a multi-pass path, a longitudinal baflle 14 is disposed across the shell between the two groups of tubes 4 and 5, this bafile being sealed to the side wall of the shell and to the inner surface of the tube sheet 2, but being spaced from the tube sheet 3 to permit the passage of fluid around the end thereof as shown. In accordance with the present invention, two oppositely disposed parallel slots or longitudinal openings 15 are cut through the shell 1 and the side edges of the baflie plate 14 are disposed within these slots, as clearly shown in Figs. 2 and 3. The slots 15 extend substantially parallel to the axis of the shell and in the embodiment of Figs. 1 and 2, these slots are located at diametrically opposite points in the cylindrical shell wall, as shown in Fig. 2. The slots 15 are preferably slightly wider at the outer surface of the shell than at the inner surface thereof, as shown in Fig. 3. The edges of the baffle plate 14 are sealed within the slots 15 by suitable means, such as the welded seams indicated at 16. The weld 16.not onl secures the baflie plate edge to the shell wa l, but, in

conjunction with the edge of the bafile plate, acts to close and seal the slot 15, whereby a fluid-tight joint between the 'bafile plate 14 and the shell 1, as Well as a fluid-tight closure for the slot 15, is produced.

In manufacturing the improved heat exchanger of the present invention, the parallel slots 15 are first cut through the walls of the shell. These slots do not separate the shell into two parts, since at least one end of the shell is still intact. The baflie plate 14 is cut to the desired size and inserted laterally into the shell through one slot 15 until its entering edge extends within the opposite slot. In this position, the opposite outer edges of the baflle plate 14 are substantially flush with the outer surface of the cylindrical shell wall 1. The baflle plate 14 is next welded in place in the slots, this operation being conveniently carried on from the outside of the shell.

When more than two passages of the fluid within the shell are desired, two or more baffles may be provided. Thus, as shown in Figs. 4 and 5, two spaced parallel baflles 17 and 18 may be employed to give three longitudinal passes of the fluid, or, as shown in Figs. 6 and 7, three spaced

parallel baflles

19, 20 and 21 may be used to produce four longitudinal passes of the fluid within the shell. In each case, the required number of oppositely disposed parallel slots are cut in the shell walls and the opposite side edges of the bafile plates are sealed within these slots in the manner described above.

The heat exchanger construction of the present invention presents numerous advantageous features. By means of the invention, the bafile plates are secured in fluid-tight engagement with the shell without the necessity of an accurate fit between these parts. Consequently, neither the shells nor the plates need be accurately machined and many expensive and laborious operations, such as the boring or grooving of the interior surface of the shells, are avoided. Substantially all-of the operations involved in mounting the bafile plates are performed from the exterior of the shell with a consequent saving of time and labor. In the finished exchanger, the tightness of the joint between the baffle and the shell can be readily ascertained from an inspection of the exterior of the device without interrupting the operation thereof.

Where the present invention is employed it is not necessary to use transverse baflles for insuring high velocity of the fluid passing through the shell. If the shell is substantially filled with tubes thus providing a relatively restricted path for the passage of the fluid through the shell, the longitudinal baffles incorporated in the apparatus in accordance with this invention can be relied upon to prevent bypassing of the fluid around the side edges of the bafiies, even though there may be a considerable difference in pressure between the inlet and the outlet. I claim: 1. A heat exchanger comprising an elon- 6 gated shell having at least one pair of longitudinally extending spaced parallel slots therethrough, a plurality of groups of tubes extending longitudinally within said shell, at least one baflie plate disposed within said 10 shell between said groups of tubes and having its side edges extending within said slots, and means for sealing the side edges of said plate to said shell within said slots. 2. A heat exchanger comprising a substantially cylindrical shell having at least one pair of spaced axially extending slots therethrough, a baflle late extending transverse-- 1y within said she I and having its side edges disposed within and at least partially closing said slots and means for sealing said side eilges of said plate to said shell within said s ots.

'3. A heat exchanger comprising a substantially cylindrical shell having at least one pair of spaced axially extending slots therethrough, a bafiie plate extendin transversely within said shell and having its side edges disposed within and at least partially clos ng said slots and welded joints extending lietween said platerand said shell within said slots and sealing said plate to said shell.

4. A heat exchanger comprising a-cylindrical shell having at least one pair of oppositely disposed axlally extendin substant1ally parallel slots therein, sai slots being wider'at the outer surface of said shellthan' at the inner surface thereof, a lurality of tubes within said shell exten ng axially thereof, a baflle plate extendin across thein- 4o terior of said shell between an substantially parallel to said tubes and having its side edges disposed within and at least partially closing said slots, and welded joints connecting said shell and the side ed es of said baflie plate within said slots, sai joints acting to completely close said slots and to secure said baiile plate to said shell.

5. A heat exchanger comprising an elongated shell having a longitudinally extendmg slot extending throu h the shell wall, a baflie plate within said s ell and having an edge thereof disposedwithin said slot, and means for sealing the edges of the slot, to the said edge of the bafile. In testimony whereof I aifix my signature.

ERIC. H; NELSON.