US2735658A

US2735658A - Tubular surface heat exchanger

Info

Publication number: US2735658A
Authority: US
Publication date: 1956-02-21
Anticipated expiration: 1973-02-21

Description

Feb. 21, 1956 s. s. cooK 2,735,658

TUBULAR SURFACE HEAT EXCHANGER Filed Nov. 2, 194 4 sheets-sheet 1 Feb. 2l, 1956 S s. CQOK TUBULAR SURFACE HEAT EXCHANGER 4 Sheets-Sheec 2 Filed Nov. 2, 1948 MNA ,fl/ll A S. S. COOK TUBULAR SURFACE HEAT EXCHANGER Feb. 21, 1956 4 Sheets-Sheet .'5

Filed Nov. 2, 1948 Feb. 2l, 1956 S. S. COOK TUBULAR SURFACE HEAT EXCHANGER 4 Sheets-Sheet 4 Filed Nov. 2, 1948 UNL . a W W f@ M f e f m f WMM M United States Patent-* TUBULAR SURFACE HEAT EXCHANGER Stanley S. Cook, Wallsend-on-Tyne, England, assignor to The Parsons Marine Steam Turbine Company Limited, Wallsend-on-Tyne, England Application November 2, 1948, Serial No. 57,933

Claims priority, application Great Britain November 5, 1947 The present invention relates to tubular surface heat exchangers in which flow of uid is parallel to the tubes in both cases, one fluid, viz., the hotter, passing through the tubes, while the other fluid passes through the interspaces between the tubes, preferably in the opposite direction, that is employing the contra-ow principle.

The rate of heat transfer increases with an increase of velocity of the uid over the surfaces and when such constructions are used as regenerative heat exchangers in a gas turbine plant the most eiicient conditions of operation require a higher fluid velocity over the external surfaces than that through the tubes. This results from the fact that the fluid passing over the tubes is at a higher pressure and pressure drop of this fluid entails much less loss of output than similar pressure drop of the low pressure tiuid passing through the tubes. However, there is a practical limit to the smallness of the pitch of the tubes which can be employed and this results, particularly for example when the tubes are of small diameter, in the cross-sectional area for flow through the interspaces being much larger than is necessary to correspond with the most eliicient employment of pressure drop for producing fluid ow through the interspaces.

The object of the invention is to increase the rate of heat transfer by increasing the velocity of the flow of fluid over the external surfaces of the tubes.

The invention consists in a heat exchanger incorporating features as set forth in the claims appended hereto.

Referring to the accompanying diagrammatic drawings:

Figure 1 is a vertical cross-sectional view of part of heat exchanger elements incorporating the present invention in one form.

Figure la is a similar view of part of heat exchanger elements incorporating a modified arrangement of filler element.

Figure 2 is a longitudinal sectional view of a heat exchanger unit.

Figures 3, 3a, 4 and 5 are vertical cross-sectional views of four modified arrangements of filling elements.

Figure 6 is a part sectional elevational view of a modilied construction of heat exchanger.

Figure 7 is a vertical cross-sectional. view on the line VII-VII thereof.

Figure 8 is a sectional plan view of a further modied form of heat exchanger.

Figure 9 is a vertical cross-sectional view on the line IX-IX thereof.

Figure l is a part sectional elevational View of a further construction of heat exchanger.

Figure ll is a vertical cross-sectional view on the line Xl-XI thereof.

Figure l2 is an elevational view of a detail, and

Figure 13 is an elevational view of a further detail.

In carrying the invention into effect according to one convenient form illustrated by way of example in Figure l as applied to a heat exchanger having tubes ar- A 2,735,658 4mientas Feb. 21, 195s ranged with triangular pitching, steel rods of circular cross-section are provided in the space between each adjacent set of three tubes, the arrangement being such that the rods a are in contact with the three tubes c. With such an arrangement the radial thermal expansion of the hotter members will press the filling members a into close contact with the heat exchange tubes c causing a slight but not injurious deformation of the tubes.

In a modilied arrangement shown in Figure la the rods b are in contact with only two tubes c.

Fluid passing over the tubes c is arranged to enter at one end d by a cross ow, e. g. as indicated in Figure 2, i. e., by a ow substantially at right angles to that along the tubes, fluid leaving at the other end e in a similar cross iiow. The lling members a or b are made shorter than the heat exchange tubes so as not to project, or in any event not to project unduly, into the portions of the interspaces over which these cross flows take place.

The filling members are preferably closely packed between the tubes so that transverse plates or the like for preventing sagging of the tubes may be dispensed with.

Means may be provided to restrain the filling members from movement along the tubes.

Instead of employing circular rods, rods of other crosssection or tubes of any desired cross-section may be substituted.

In the arrangement illustrated in Figure 3, with rectangularly pitched tubes, the filling members a as in Figure l are all arranged to be in contact with all the adjacent heat exchange tubes and in a modified arrangement shown in Figure 3a the illing members b are in contact only with certain of the tubes c.

In an alternative construction illustrated in Figure 4, corrugated plates f, or as in Figure 5, fiat plates, or builtup pairs of plates g are employed between sets of tubes c. Where built-up pairs of plates are employed the edges of the pairs may be sealed.

Where rods or plug tubes are employed as filling members, these may be inserted through tube holes in the tube plates. For example, after the tubes are inserted in the bottom row the filling rods can be passed through the next row of holes before the tubes are inserted in the latter, and so on, but to facilitate their assembly or removal a hole for access with a cover B may be provided as indicated in Figures 6 and 7, which show a single flow heater.

For a two-flow or multi-How heater a separate hole for access may be provided for each flow or a single hole giving access to two tlows may be provided, as shown at C in Figures 8 and 9.

Where the lling members comprise sheets, strips, or the like, as shown in Figures 4 and 5, for convenience of insertion these may be made in short lengths, or the casing may be provided with a wide and long opening and cover, as indicated at D in Figures l0 and ll.

In order to restrain the filling members against end movement those of the rod type may be provided with small projecting ends E engaging the tube plate as shown in Figure l2, and those of the strip type may be restrained by a projection attached to or integral with the casing as shown in Figure 13.

What is claimed is:

1. A tubular surface heat exchanger, comprising a plurality of tubes for conducting a hotter fluid, a casing surrounding the tubes and tube plates at the ends of the tubes for supporting the same in parallelism and spaced relation, filling members disposed in the interspaces between and in close contact with the tubes throughout substantially their entire lengths but out of contact' therewith adjacent the tube plates, the said filling members being free to move crosswise of the tubes except as restrained thereby, supply and discharge connections to the casing for circulating` a. ceoler luid,A the said supply and. dis charge connections being pQSitioned for communicating with the interspaces between the tubes adjacent the tube plates, whereby the, cooler uid is suppliedandidischarged by a cross. flow. but circulated inparallclism toy the hotter uid.

2. A heat` exchanger as claimed in claim 1, wherein the filling members comprise plates disposed. between adjacent rows of tubes.

3. A heat exchanger asV claimed in claim 2, wherein said platesextend over the full width of the exchanger.

4. A heat exchanger as claimedv in claim 1, wherein said filling members comprise built-up structures consisting of pairs of thin plates with a4 space between, ribbed internally and sealed at the, ends or locally enlarged or corrugated so as to iit between the tubes.

5. A heat exchanger as claimed in claim 1, wherein the filling members comprise metal rods furnishedy with small diameter projecting ends engaging end tube plates.

6. A heat exchanger as claimed in claim 2, wherein said plates are restrained by a projection rigid with the casing.

7. A heat exchanger as claimed in claim 1, wherein the filling members are made of a plurality of short lengths.

References Cited in thc le of this patent UNITED STATES PATENTS 1,350,320 Lovekin Aug. 24, 1920 1,867,163 Loebell July 12, 1932 1,920,800 McCausland Aug. l, 1933 2,125,972 Wilson et al Aug. 9, 1938 2,185,928 Simpson et al. Jan. 2, 1940 2,349,143 Chute et al May 16, 1944 POREiGN PATENTS 306,367 Great Britain Feb. 2l, 1929