US2620169A - Plate type heat exchanger - Google Patents

Description

W. L. GROSS ETAL PLATE TYPE HEAT EXCHANGER Dec. 2', 1952 5 Sheets-Sheet 1 Filed June 16, 1949 Inventors:

H" A IZGIW M Dec. 2, 1952 w. L. GROSS ET AL 2,620,169 PLATE TYPE HEAT EXCHANGER Filed June 16, 1949 3 Sheets-Sheet 2 l/ IIHI I zffor'neys 1952 w. GROSS ET AL 2,620,169

PLATE TYPE HEAT EXCHANGER Filed June 16, 1949 5 Sheets-Sheet 5 Inventors aha-Ln M Attorneys Patented Dec. 2, 1952 UNITED STATES PLATE TYPE HEAT EXCHANGEB Application June 16, 1949, Serial No. 99,549 In Great Britain June 23, 1348 1 Claim. l

The invention relates to plate type heat exchangers for heat exchange between gaseous fluids in general, and without prejudice to this general applicability, in particular to heat exchangers for use in gas turbine plant, such as for the heat exchange between the exhaust gases of a gas turbine and the compressed air fed into its combustion chambers.

It is an object of the invention to provide a heat exchanger which is of a high thermal emciency, i. e. wherein the ratio of heat transferred from one fluid to the other, to the heat which can theoretically be transferred, is high.

It is another object of the invention to provide a heat exchanger which is of a high mechanical efficiency, 1. e. wherein the pressure drop in either or both passes is low.

Other objects are:

Freedom from stresses due to differential thermal expansion; small requirements of space, for mobile plant particularly in the dimensions across the direction of movement; low weight.

Other objects will become apparent later from the description of some preferred embodiments of the invention wherein a balanced combination of the aforementioned objects has been achieved.

According to one aspect of the invention a plate type heat exchanger comprises identical plates arranged in pairs, each plate having parallel corrugations, the plates of each pair being reversed relatively to and connected with one another so as to enclose separate channels for the one heat exchanging fluid between their corrugations facing one another, adjacent pairs being spaced from one another so as to enclose continuous duct spaces for the other heat exchanging fluid and being connected with one another on their transverse edges so as to isolate the said continuous duct spaces from the said separate channels, the said continuous duct spaces being laterally open adjacent the ends of said plates, and closed intermediately.

Preferably these plates have parallel corrugations of uniform shape and arranged at uniform pitch except the last corrugation adjacent the one longitudinal edge of the plate, the plates of each pair being reversed relatively to one another about an axis parallel to their plane and transverse to the direction of the corrugations and alternate pairs being reversed with respect to one another about an axis perpendicular to the aforesaid axis so as to stagger the said channels in alternate pairs relatively to one another.

These pairs of plates or plate sandwiches as they may be called registering in outline with one another form a bank having straight-through channels enclosed within each individual plate sandwich but with the continuous duct spaces between adjacent sandwiches left laterally adjacent their ends but closed intermediately open. Bafiles or side walls have therefore to be arranged in order to separate entrance openings on both sides of the one end of these continuous duct spaces from similar exit openings on the other end. The entrance openings on each side of the bank of plate sandwiches are connected to an entrance manifold, and the exit openings on each side of the said bank are connected to an exit manifold, the two entrance manifolds and the two exit manifolds, respectively, being in connection with one another preferably at a front end of the said bank.

The straight-through channels will offer in general less resistance and consequently cause a smaller pressure drop than the continuous duct spaces.

Preferably these straight-through channels will therefore form the hot pass of the heat exchanger, for example for the exhaust gases of a gas turbine, while the continuous duct spaces form the cold pass, for example for the air delivered from the compressor to the combustion chamber of a gas turbine, so that the smaller pressure drop occurs on the exhaust side of the gas turbine whereby it affects the overall efflciency of the gas turbine-compressor-set less than it would on the high pressure side.

These and other features of the invention will be explained in detail with reference to some preferred embodiments.

In order to be better understood and readily carried into effect, the invention will now be described by way of example with reference to the accompanying drawings of which:

Fig. 1 is a broken-off part elevation of consecutive pairs of plates of a preferred embodiment of the invention.

Fig. 2 is a corresponding plan view, partly in top view and partly in section on the lines A-A and BB, respectively, of Fig. 1.

Fig. 3 is a side elevation to Fig. 1 partly in section on line C-C and partly as viewed in the direction of the arrows D-D of Fig. 1.

Fig. 4 is a side elevation in section on line E-E of Fig. 1.

Fig. is an isometric part view of two consecutive pairs of plates.

Fig. 6 is an isometric overall view, partly broken away, of the heat exchanger.

Referring now to Figs. 1 to 5, each plate I has parallel grooves 2 of trapezium shaped cross section arranged at a pitch p from another (Fig. 2). The grooves nearest to the edges of the plate are at half the said pitch (12/2) and a quarter the said pitch (19/4) from their respective edges. The latter grooves are of reduced width.

Two plates reversed with respect to one another about an axis parallel to their own plane perpendicular to the longitudinal direction of said grooves form a pair or sandwich of plates Ia enclosing between themselves hexagonal channels 3 of a uniform size except the channel 3 adjacent to one of their longitudinal edges which is of reduced size.

These plate sandwiches are preferably resistance welded at the contacting strips 4 between adjacent channels, and are welded at the edges 5.

By reversing alternate plate sandwiches about an axis parallel to the grooves or perpendicular to the plane of the plates the pattern shown in Fig. 2 is obtained according to which the channels 3 in adjacent pairs or sandwiches are staggered one half pitch (in/2).

The cross section of the continuous spaces 6 between adjacent plate sandwiches has lateral projections I between adjacent channels which projections, being complementary to the trapezium shaped grooves 2, are themselves trapezium shaped.

By the staggering of the channels 3, these projections I, too, are staggered, and made to face with their large open bases the fiat portion of the adjacent plate in the middle of each channel.

When the channels 3 and the duct spaces 6, l are passed by the two heat exchanging fluids in countercurrent in the central portion of the plates, the most favourable flow and heat exchange conditions are obtained.

At their transverse edges 8 (upper edge, Figs. 1-4 and lower edge, Fig. 5) the opposite plates of adjacent plate sandwiches are welded together so as to close the duct spaces 6, I there, while leaving the channels 3, 3 open (Figs. 3 and 4) Adjacent the sealed transverse edges 8 the duct spaces 6 are enlarged so as to form entrances 6a adjacent the upper edge and exits adjacent the lower edge. These enlargements are achieved by reducing the depth of the grooves 2 in the region of section A-A (Figs. 1-4) to that of shallower grooves 2a resulting in somewhat reduced channel sections 3a in this region.

Adjacent sandwiches of plates are spaced in plan by means of racks or combs 9 engaging their longitudinal edges 5 near their ends. The racks 9 are eventually welded to the plate sandwiches (Figs. 1 and 2).

Referring now to Fig. 6, two banks of plate sandwiches 2 of the kind described in detail hereinabove with reference to Figs. 1-4 are arranged side by side in a common casing.

The straight-through channels 3 within the plate sandwiches, the upper ends of which are 4 visible in Fig. 6, form a system of honeycomb open at both ends, the lower end being adapted to be connected with the exhaust elbow of a gas turbine and the upper end to the stack leading to the open atmosphere.

The continuous duct spaces 6 are closed on the top and bottom at 8, and laterally open, and the common casing of the heat exchanger is divided horizontally into an upper entrance space, communicating with the lateral entrance openings Ba of these duct spaces, and a lower exit space, communicating with the lateral exit openings 6b.

The casing consists of a front flange plate 42 with an entrance opening H in the middle of the upper half and two exit openings 21, 28 on both sides of the lower half, side walls 3| and arched manifolds 20, 2i and 22, 23 linking up with the said side walls, front plate, and arched transverse front ducts l8, l9 and 25, 26. There is also a rear wall and transverse ducts on the rear of the casing.

The inner edges of the arched transverse ducts and arched manifolds are connected by rectangular frames, of which the one 44 on the top of the heat exchanger is partly shown in Fig. 6. These frames are provided for connection with the exhaust of the gas turbine and with the stack, respectively.

Between the two banks of plates there are enclosed an upper central entrance manifold I2 and a lower central exit manifold which is not visible in Fig. 6.

These central manifolds are covered on top and bottom respectively by a pressure-resisting, preferably corrugated, cover strip 45. Combs 9 (Figs. 1 and 2) are connected with the edges of these cover strips and the longitudinal inner edges of the frames 44. Similar combs or racks 46 run along the longitudinal centre lines on top and bottom of each bank of plates so as to keep the latter properly spaced and to prevent any accordion-like sagging thereof. These racks 46 are connected with the front and rear edges of the frames 44.

The whole structure of the heat exchanger is carried by the middle horizontal plate member [3, which is connected to box girders 30 and 35, so as to enclose two rectangular openings through which the two banks of plates are passed.

While we have described a preferred embodiment of our said invention, we do not wish to exclude the various modifications thereof which may readily offer themselves to those skilled in the art.

What we claim as our invention and desire to secure by Letters Patent, is:

A plate type heat exchanger comprising a pressure-resisting casing, pairs of plates each having longitudinal corrugations at substantially regular intervals, the corrugations of the two plates of one pair contacting one another and between one another enclosing separate channels for one of the heat exchanging fluids, said pairs forming sandwiches registering with one another in outline and forming a bank of such sandwiches ar ranged within said casing, racks attached to said casing adjacent the ends of the said sandwiches and spacing the same from one another, side walls of the said pressure-resisting casing bafiiing the lateral edges of the said sandwiches merely at their middle portions, the spaces formed between adjaoent sandwiches thus being laterally open on both sides adjacent the ends of said plates and substantially closed intermediately, and being moreover closed at their transverse edges for the enclosure of continuous duct pass- UNITED STATES PATENTS ages for a second heat exchanging fluid, resilient Number Name Date arched walls connecting the edges of said side 1417 337 Jungerhem May 23 1922 walls with the said racks and with the top and Jacobus NOV. 1927 bottom edges of the plates at both ends of the 5 1,726,458 Tenander Aug. 27 1929 id bank, the said resilient arched walls en- 1334362 Clarke 12 1929 Closing separate manifolds respectively connect- 1,775,103 Hume Sept 9, 1930 ing the said continuous duct passages where lat- 30 5 Camel-ism May 19, 1931 emlly LAWRENCE GROSS 10 1,831,533 Hubbard Nov. 10, 1931 JOHN OLIVER PHILIP HUGHES. FOREIGN PATENTS PAUL HEINZ WALTER WOLFF. Number Country Date ADOLF FRANKEL. 285,550 Great Britain Feb. 16, 1928 REFERENCES CITED 15 The following references are of record in the file of this patent:

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