US3042382A

US3042382A - Plate type heat exchangers

Info

Publication number: US3042382A
Application number: US774571A
Authority: US
Inventors: Hryniszak Waldemar
Original assignee: CA Parsons and Co Ltd
Current assignee: CA Parsons and Co Ltd
Priority date: 1957-10-31
Filing date: 1958-10-27
Publication date: 1962-07-03
Anticipated expiration: 1979-07-03

Description

July 3, 1962 w. HRYNlszAK PLATE TYPE HEAT EXCHANGERS 6 Sheets-Sheet 1 Filed Oct. 27, 1958 wmf/,TTT n MMM,"

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IMII July 3, 1962 w. HRYNlszAK 3,042,382

PLATE TYPE HEAT EXCHANGERS Filed Oct. 27, 1958 6 Sheets-Sheet 2 f i wiff 1f f July 3, 1962 w. HRYNlszAK 3,042,382

PLATE TYPE HEAT ExcHANGERs Filed Oct. 27, 1958 6 Sheets-Sheet 3 July 3, 1962 w. HRYNlszAK 3,042,382

PLATE TYPE HEAT EXCHANGERS Filed Oct. 27, 1958 6 Sheets-Sheet 4 /Ljf 'r1-@ 6 Sheets-Sheet 5 Filed OCL. 27. 1958 July 3, 1962 w. HRYNlszAK 3,042,382

PLATE TYPE HEAT EXCHANGERS Filed Oct. 27, 1958 6 Sheets-Sheet 6 3,042,382 PLATE TYPE HEAT EXCHANGERS Waldemar Hryniszak, Newcastle-upon-Tyne, England,

assigner to C. A. Parsons & Company Limited, Newcastle-upon-Tyne, England Filed ct. 27, 1958, Ser. No. 774,571 Claims priority, application Great Britain Oct. 31, 1957 1 Claim. (Cl. 257-245) This invention relates to plate type heat exchangers of the kind comprising one `or more heat exchange elements which elements comprise a series of spaced sheets separated from one another by side wall elements which form a flow channel, the inlets and outlets of which are displaced from the main direction of tlow through said channel and such that the outlets and inlets of adjacent chan nels are staggered with respect to one another, said flow channels being subdivided into a plurality of flow channels by corrugated inserts between said spaced sheets. It relates especially but not exclusively to heat exchangers including heat exchange elements according to British Patent No. 718,991, that is to say in which the paths for hot fluid and cold iiuid are separate, and in which heat transfer takes place through a wall separating the hot fluid and cold fluid, the heat exchanger consisting of one or more heat exchange elements, each element comprising a number of cells arranged in the form of a column or stack, each cell consisting of a at base sheet and side walls which dene a flow channel all of said side walls in the element being of identical shape and such that inlet and outlet openings to and from each cell are formed, which openings are angularly displaced from the line of ldirection of the flow channel, said side Walls being inverted in adjacent cells thereby causing the inlets and outlets `of one cell to be angularly displaced from those of an adjacent cell thus allowing for separate inlets and outlets for the hot and cold fluids respectively and allowing them to flow in counterliow with respect to one another in alternate cells, said ow channel being subdivided into a number of liow paths by means of a corrugated strip providing an increased heat transfer surface and structurally strengthening the cell, and in which the side walls `of each cell are two in number and the corrugations of the corrugated strip are parallel and straight throughout their entire length. v

The element of that British patent was adapted for easy construction and for positioning in a casing in ducts to which the heat exchanging fluids could be led.

When such elements are located in a series of such ducts in a casing not only is the weight of the heat exchanger increased by a certain amount of material which does not assist heat transfer, but in cases where the heat exchanging iiuids are at substantially different pressures it has been found that difficulties arise in preventing leakage in the duct containing the element between inlets and outlets for said fluids especially across the contacting faces Of element and duct.

The main object of the present invention is to provide improved means for conveying the heat exchanging fluids to and from said heat exchange elements.

In British Patent No. 732,977 is described -means whereby elements which may be in accordance with British Patent No. 718,991 located in ducts as described above, can be cleaned regularly and automatically, but the devices described therein are not applicable to the construction of elements in accordance with the present invention as set out in the statements of invention below and a further object of :this invention is to provide means for cleaning at regular intervals the passages of a heat exchange element incorporating the improved means for aired States `latent C 3,042,382 Patented July 3, 1962 ice conveying the heat exchange fluid to and yfrom the element as set out in the statements of invention below.

A lfurther object is to provide means whereby two or more of said elements can be operated together.

The invention consists in a plate type heat exchanger comprising one or more heat exchange elements which elements comprise a series of spaced sheets separated from one another by side wall elements which form a ow channel the inlets and outlets of which are displaced from the main direction of flow through said channel and such that the outlets and inlets of adjacent channels are staggered with respect to one another, said flow channels being subdivided into a plurality of flow channels by corrugated inserts between said spaced sheets in which element ducts for the heat exchanging `fluids are welded or otherwise bonded to the element inlets and outlets.

The invention also consists in a plate type heat exchanger in which the paths for hot iluid and cold fluid are separate, and in which heat transfer takes place through a wall separating the hot fluid and cold fluid, the heat exchanger consisting of one or more heat exchange elements each element comprising a number of cells arranged in the form of a column or stack, each cell consisting of a fiat base sheet and side walls which dene a flow channel, all of said side walls in the element being of identical shape and such that inlet and outlet openings to and from each cell are formed, which openings are angularly displaced from the line of direction of the flow channel, said side walls being inverted in adjacent cells thereby causing the inlets and outlets of one cell to be angularly displaced `from those of an adjacent cell thus allowing for separate inlets and outlets for the hot and cold fluids respectively and allowing them to `ilow in counterflow with respect to one another in alternate cells, said flow channel being subdivided into a number of flow paths by means of a corrugated strip providing an increased heat transfer surface and structurally strengthen ing the cell, and in which the side walls of each cell are two in number and the corrugations of the corrugated strip are parallel and straight throughout their entire length, the characteristic feature according to the present invention being that the element ducts for the heat exchanging yiiuids are welded or otherwise bonded to the element inlets and outlets.

The invention also consists in a plate type hea-t exchanger in accordance with either of the preceding two paragraphs in which only ducts for high pressure fluid are welded or otherwise bonded to the element.

The invention also consists in a plate type heat exchanger in accordance with any of the preceding three paragraphs in which the ducts are formed 4by curved sheets which are welded to the element adjacent the inlets and outlets the said sheets forming an enclosed space with openings at opposite `faces thereof into which tubular ducts are fitted.

The invention also consists in a plate type heat eX- changer in accordance with any of the preceding four paragraphs in which the ducts are formed by forming a longitudinal slot in a tubular duct vfor a distance intermediate its ends, forming slots in a circumferential direction for a distance equal to half the circumference of the duct at each end of the longitudinal slot, the portion of the duct bonded by the slots being opened up and welded to the element so as to form a duct having tubular portions at each end thereof and a portion of domed cross-section in between.

The invention also consists in a plate type heat eX- changer in accordance with any of the preceding five paragraphs in which two or more elements are arranged in alignment each separated lby a heat insulating member the aligned members having common inlet and outlet ducts.

The invention also consists in a plate type heat exchanger in accordance with any of the preceding six paragraphs in which the corrugated sheet in each ilow channel is in two parts spaced from each other in Athe di-rection of flow, a slot being formed in each side of the element opening into said spaces between the corrugated sheet and a duct welded to the element each side thereof and having an opening in one side therein in communication with said spaces so that cleaning Huid may ybe introduced into each flow channel.

The invention also consists in plate type heat exchangers substantially as described below with reference to the accompanying drawings in which:

FIGURES la and lb show the form of alternate ilow channels of a heat `exchange element used in accordance with one form of the invention;

FIGURE lc is a part section on line lc-Ic of FIG- URE lato a larger scale;

FIGURE 2a is a plan view of two elements in axial alignment and showing a ducting arrangement used in accordance with one form of the invention;

FIGURE 2b is an end elevation of FIGURE 2a;

FIGURE 2c is a section on line 2c-2c of FIG- URE 2b;

FIGURE 2d is a section on line 20L-2d of FIG- URE 2c;

FIGURE 2e is a section through the aforesaid element, one half showing details of one ow channel and the other half details of an adjacent channel;

FIGURES 3a, 3b, 3c and 3d respectively show details of one -form of duct karrangement used in accordance with the invention;

FIGURES 4a, 4b, 4c and 4d respectively show details of an alternative form of duct arrangement used in accordance with the invention; Y

FIGURE 4e is a section, on line 4e-4e of FIG- URE 4b;

FIGURE 5 is a View of a modied form of end plate;

FIGURE 6 is a view of a centre corrugated sheet used in accordance with one form of the invention;

FIGURES 7a and 7b show details of a side wall used in accordance with one form of the invention;

FIGURES 8a., 8b, 8c, 8d and 8e respectively show details of a cleaning arrangement of the ow channels;

FIGURES 9a and 9b show details of a side wall in accordance with the construction of FIGURE 8.

In carrying the invention into eifect in the forms illustrated by way of example and referring rst of all -to FIGURES ltr-lc, a heat exchange element is built up of a series of spaced sheets 1 (FIGURE lc) of hexagonal shape separated by side walls 2a, 2b, to form a ilow channel between each pair of sheets. As can be seen from FIGURES la and 1b the side walls lie along edges of the sheets and, in the spaces enclosed by the said side walls, are arranged corrugated sheets which divide .the flow channel up into a number of smaller channels vfor the flow of heat exchanging fluid.

The corrugated sheets comprise a centre sheet 3a and inlet and outlet corrugated sheets 3b and 3c respectively. The side walls 2a, 2b are arranged so that the inlets and outlets are displaced from the direction of ow through the centre sheet 3a and accordingly the corrugations in the sheets 3b and 3c are disposed at an angle to the corrugations of sheet 3a as can be seen in FIG- URES 1a and 1b.

The heat exchange element is built up by having flow channels of the form shown in FIGURE la alternating with ilow channels of the type shown in FIGURE 1b, so that ow channels for lhot fluid alternate with channels for cold fluid.

To complete an element end plates of similar shape to the spaced sheets but slightly thicker are added at each end of the element. In one example the spaced 4 sheets 1 are 0.0028 thick and the end plates 0.048 thick.

When such heat exchange elements are to be subjected to high temperatures of the order of 600 C. and also to a pressure difference it is often advisable to use two elements in axial alignment with each other separated by a heat insulating pad, for example of asbestos, rather than a single element, so as to keep the length of an element within desirable limits. It 4has been Ifound, in this respect, that the -best length for an element, under these `temperature conditions and when a pressure difference exists between the heat exchange fluids, is of the order of six inches and with the thickness of sheets envisaged this would mean about flow channels in each element.

FIGURE 2n shows a plan view of two elements in axial alignment and incorporating ducts for conducting one of the heat exchange uids to and from the two elements. While a duct can be used for both i'luids it is only necessary to have the duct arranged for the lluid at the higher pressure.

FIGURE 2b shows an end elevation of the elements showing the general shape of the element and attached ducts.

FIGURE 2c is a section on line 21e-2c of FIGURE 2b, but the cross section through the flow channels is not shown. In this view the elements can be seen separated axially by a pad 4 of asbestos.

FIGURE 2d shows a section on line 2d-2d of FIG- URE 2c and is a section through the asbestos pad 4.

FIGURE 2e is in two parts, the left hand side being a section through a flow channel of the type shown in FIGURE la, whilst the right hand side shows a section through a flow channel of the type shown in FIGURE 1b.

FIGURES 3er-3d sho-w details of the form of duct incorporated in the element of FIGURES 2li-2c. It consists of a plate 5 of the shape shown in FIGURE 3a which is bent into the shape shown in plan, and elevation and side elevation in FIGURES 3b, 3c and 3d respectively, to form a circular opening for pipes which are then welded to the plates at each end thereof.

To form the duct assembly, plate 5 and the attached pipes 6, are then welded yor otherwise bonded to the'inlet and outlet for high pressure uid as can be seen in FIG- URES 2a, 2b and 2c.

As will be clear from FIG. la, the placement of the side walls 2a and 2b is such as to allow opening for ilow of fluid between the upper left and lower right opposite sides of the hexagonally shaped cell, while in the cell shown in FIG. 1b, the placement is such as to allow `flow between the upper right and lower left opposite sides ot the hexagonal cell. iThe ducting for the high pressure fluid (FIGS. 2b, 2e, 2a) is positioned with relation to the stack of cells (alternately of the type shown in FIG. la and of the type shown in FIG. 1b) so as to provide for ow of the high pressure fluid through cells of the type shown in FIG. la between the two ducts 5 as shown in FIG. 2e.

An alternative duct arrangement is shown in FI- URES 4a-4e. In this form a duct 7 has radial and axial slits and 9 respectively cut in it (see FIGURES 4a and 4b) intermediate its ends and the slit portions are then opened out as shown in FIGURE 4c to form two llap portions 10 (see FIGURE 4c), which are subsequently welded to the inlet and outlet of the element as shown in FIGURE 4d.

With this latter form of duct both end plates in the case of a single element or if two elements are axially aligned the two extreme end plates, must be modied as shown in FIGURE 5 to allow the welding of duct 7 to the element.

The invention also provides for the cleaning or" such elements in a simple way.

Referring to FIGURE la the centre sheet 3a has slits 11 and 12 cut in it which stop short of each other in the centre of `the sheet so that the resulting shape of the sheet is rather like a letter H. This can be seen more clearly by reference to FIGURE 6 which shows the form of the centre sheet 3a. The side walls 2a, 2b have a projection 13 (see FIGURES 7a and 7b) in which is formed a hole 14. Similarly each spaced sheet has a projection which coincides with projection 13 when the element is assembled so that a continuous duct 15 (see FIGURE 2a) is formed, down each side of the element. In alternate sets of side walls as shown in FIGURES 7a-7b a slit 16 is cut so that when in position in the element the slit 16 puts the duct 15 in communication with the slits 11 and 12 in the centre sheet 3a. Cleaning air or fluid is then passed periodically through ducts 15 through connection 17 (FIGURE 2a) from which ducts it enters the corrugations and removes dust and other particles deposited there. Normally it is sufficient to clean only the low pressure side as on the high pressure side the passages are virtually self cleaning. If desired however, the cleaning uid can be passed through all the flow channels instead of only alternate ones by simply forming slits 16 in the side walls of each ow channel.

In an alternative `cleaning arrangement shown in detail in FIGURES SLI-8e and 9a and 9b each side Wall is provided with a notch 17 and then after the element has been assembled and brazed together a milling cutter is used to cut out a further notch 18 of circular shape which opens into the notch 17. Into the notch 18 is Welded a pipe 19 having a longitudinal slit 20 coinciding with the notch 17. This pipe 19 is then connected to a supply of cleaning air or cleaning fluid through connection 21 (FIGURE 8c).

If it is desired to clean only the low pressure side of the channels for one heat exchange fluid then, as before, all that is necessary is for the side Walls of alternate ow channels only, to have notches 17 cut in them.

I claim:

A heat exchanger comprising an assembly of hexagonally shaped flat sheets, side walls spacing said sheets, each side wall having two portions at an angle to each other, each side wall lying along adjacent sides of a hexagonal sheet at opposite corners thereof, a rectangular shaped corrugated sheet disposed between each pair of sheets with the two shorter edges lying parallel to two opposed parallel portions of the side walls and the corrugations running parallel to said shorter edges, the corrugations between each pair of sheets being parallel to one another and the side walls being disposed in adjacent pairs of sheets to provide inlets and outlets for -a flow channel between one pair of sheets which are displaced from those lfor the flow channel between an adjacent pair of sheets, inlet and outlet means for conducting one heat exchanging iluid to the inlets and from the outlets of alternate flow channels and inlet and outlet means for conducting another heat exchanging uid to the inlets and from the outlets of the remaining ow channels, the inlet and outlet means for at least one said fluid comprising inlet and outlet headers for the inlets and outlets for that heat exchanging Huid, one header being on the inlet face and the other on an outlet face of the heat eX- changer, said headers consisting of tubular members having a slot formed therein for a distance intermediate their ends, and slots formed in a circumferential direction for a distance equal to half the circumference of the members at each end of the longitudinal slot, the portion of the duct bounded by the slots being open at the side thereof facing the said slots and having side portions continuing the duct wall remote from the said slots, means joining the said side portions to the heat exchanger to form a header having tubular portions at each end thereof and a portion of domed cross-section in between, and end plates at each end of the heat exchanger which seal the ends of the domed portions of the duct and to which the tubular ends of the duct are bonded.

References Cited in the le of this patent UNITE STATES PATENTS 1,717,033 Hinsch et al June 11, 1929 2,439,208 Glover Apr. 6, 1948 2,566,310 Burns et al Sept. 4, 1951 2,571,631 Trumpler Oct. 16, 1951 2,782,010 Sirnpelaar Feb. 19, 1957 FOREIGN PATENTS 162,308 Australia Mar. 31, 1955