US3259183A

US3259183A - Plate type heat exchanger utilizing movable plate

Info

Publication number: US3259183A
Application number: US247726A
Authority: US
Inventors: Otto Konrad
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1961-12-30
Filing date: 1962-12-27
Publication date: 1966-07-05
Anticipated expiration: 1983-07-05
Also published as: DE1401657B2; DE1401657A1; GB1023081A

Description

July 5, 1966 o. KONRAD 3,259,183

PLATE TYPE HEAT EXCHANGER UTILIZING MOVABLE PLATE Filed Dec. 27, 1962 5 Sheets-Sheet 1 I H M; I

I/VVE/VTOR 07'7'0 KO/VRAD y 5, 1966 o. KONRAD 3,259,183

PLATE TYPE HEAT EXCHANGER UTILIZING MOVABLE PLATE Filed Dec. 27, 1962 5 Sheets-Sheet //v VE/V TOR OTTO HO/VRAD July 5, 1966 o. KONRAD 3,259,183

PLATE TYPE HEAT EXCHANGER UTILIZING MOVABLE PLATE Filed Dec. 27, 1962 5 Sheets-Sheet 3 IN VE/VTOR OTTO hQ/VRAD United States Patent 5 Claims. 61. 165-166) My invention relates in general to heat exchangers for transfer of heat between two fluids, and more particularly to heat exchangers for two fluids which are under very high pressure.

Plate heat exchangers are used in industry in many cases with good results for heat transfer between fluids. In cases where the temperature diflerence between the streams of fluid is small, plate heat exchangers have particular advantages over conventional heat exchangers, for example those having tubes, by reason of their large heatex-changing surface and small enclosed space. Owing to the fact that plate heat exchangers are composed of flat plates, the use of such heat exchangers has however been limited to low pressures. Generally speaking a pressure of 20 atmospheres is not exceeded.

Substances under high pressure are being increasingly used, i.e. conveyed or reacted, in process engineering. Heat exchangers required for these substances under high pressure are however thick walled and therefore very heavy. On the other hand although tube heat exchangers have thin walls, on the whole they require a larger enclosed space.

The present invention is directed to the development of a plate heat exchanger for high pressures which will make use of the known advantages of this construction without being limited to low pressures by the flat shape.

Accordingly it is the principal object of my invention to provide a plate heat exchanger for high pressure which is simple and dismountable.

Another object of my invention is to provide a plate heat exchanger using thin plates. A further object of my invention is to provide a heat exchanger suitable for varying pressures up to about 6000 atmospheres.

Further objects and advantages of the invention will become apparent from the following detailed description of two preferred embodiments thereof, taken in connection with the accompanying drawings, in which:

FIGURE 1 is a longitudinal sectional view of a plate heat exchanger having two stationary end plates in accordance with my invention;

FIGURE 2 is a longitudinal sectional view of a plate heat exchanger according to the invention which has a widened portion and is provided with two stationary end plates and one movable end plate;

FIGURE 2:: is a plan View of the heat exchanger of FIG. 2; and

FIGURE 2b is a sectional view taken through line 2b2b of FIG. 2.

The hermetically sea-led plate or piston heat exchangers as shown in FIGURES 1 and 2 are intended for use in systems having fluids under high pressure.

The plate heat exchanger according to this invention for the exchange of heat between two fluids under high pressure comprises a cylindrical vessel capable of withstanding the high pressure and closed .at each end by a stationary end plate, each end plate being provided with an inlet for one of the fluids and an outlet for the other fluid, a plurality of circular plates located between the end plates and pressed together with sealing means between them to form a set of plates spaced apart from each other, the spaces between alternate pairs of circular of the pressure vessel.

"ice

plates being in fluid communication with the inlet and outlet for one of the fluids, and the remaining spaces being in fluid communication with theinlet and outlet for the other fluid.

The plate heat exchanger also comprises sealing means between the ends of said set of plates and the stationary end plates, said set of plates being pressed together by pressure exerted thereon by said end plates.

The heat exchanger further comprises a flange on each end of the pressure vessel, and means on said flanges for securing the stationary end plates, so that pressure can be exerted on said set of plates.

To diminish the effective pressure, a bore is provided in one of the stationary end plates which communicates at one end with the inlet in said end plate and at the other end with the space between the set of plates and the Wall of the pressure vessel.

In a modified embodiment of the invention, in order to provide uniform adjustment of the pressure exerted on the set of plates, the upper part of the cylindrical pressure vessel is widened and a stepped moveable plate or piston is provided which engages the wall of both the lower narrower portion and the upper wider portion of the pressure vessel and is provided with bores for the passage of the two fluids.

The stepped movable plate or piston, which is advantageously constructed as a stepped piston, is sealed in both its wider and narrower portions against the inner Wall of the pressure vessel by suitable sealing means, e.g., O-rings.

Since cylindrical pressure vessels are best for Withstanding high pressures, the plates are circular in shape. This is particularly advantageous because the clamps by which rectangular plates have hitherto been pressed together externally to seal the individual plates against each other and the surrounding space, can be dispensed With according to the invention. The plates are laid one above another on the lower end plate until the required number is in position and then the set of plates is pressed together by superposition of the upper end plate. The sealing means in the end plates and between the circular plates are such that only part of the compressive force exerted by the end plates is taken up by the seals in the plates.

The bulk of the force is taken up by rigid supports. Bores are provided in the end plates and the heat-exchanger plates for passage of the fluids which are to ex-. change heat.

In order that the compressive pressure on the set of plates may be maintained automatically at a predetermined value, the plate heat exchanger in the modified form is provided with a movable end plate (piston).

For this purpose the upper portion of the pressure vessel is widened and the movable end plate (piston) is made with its lower part to fit the smaller internal diameter and its upper part to fit the larger internal diameter One or more bores are provided through the wall of the widened portion adjacent the junction with the narrow portion of the pressure vessel to provide communication between the space formed between the movable end plate (piston) and the wall of the pressure vessel, and the atmosphere. If the movable end plate (piston) is provided with one or more bores providing communication between the upper and lower sides thereof, i.e. said bores communicate at one end with the space between the movable plate (piston) and the adjacent stationary end plate and at the other end with the space surrounding the set of plates within the narrower portion of the vessel, the movable plate (piston) being under the pressure of the fluids exerts a compressive force on the set of plates according to the diiference in area of the two sides of the movable end plate (piston) and the operating pressure.

When the two fluids which are exchanging heat are under different pressures, it is advantageous to allow the fluid under the higher operating pressure to act on the movable end plate (piston). Owing to the bores through this movable end plate (piston), the space surrounding the set of plates is also exposed to the action of the higher operating pressure. The seals and supports of the set of plates are therefore stressed only by the prevailing differential pressure between the outer space surrounding the set of plates and the internal space of the set of plates.

A stationary end plate is provided above the movable end plate (piston), and this stationary end plate has two bores similar to those in the lower end plate. A slidable connecting tube is provided between the upper stationary end plate and the movable end plate (piston). This tube is secured to the movable end plate (piston) and passes into one of the bores in the upper stationary end plate and is sealed against this bore by suitable sealing means, e.g., an O-ring.

The difference in pressure in the spaces between the set of plates on the one hand and in the space surrounding the set of plates on the other hand is less than in the case of the conventional plate heat exchangers not having a pressure-tight wall. It is therefore possible to use even thinner plates and thus achieve better heat transfer.

Another advantage of the set of plates according to this invention is the possibility of obviating clamps. In the first embodiment of the invention, the set of plates is pressed between the upper and lower stationary end plates, and in the second embodiment between the movable end plate (piston) and the lower stationary end plate. In the latter case, the compressive force is determined by the operating pressure. The amount of this compressive force may be varied to a great extent in the design of the apparatus by varying the relative areas of the upper and lower faces of the movable end plate (piston).

Referring particularly to FIG. 1, a thick-walled pressure vessel is closed by lower and upper

stationary end plates

4 and 5 secured to

flanges

2 and 3 provided on the casing 1 of the pressure vessel. The casing 1 contains a set of plates 7 consisting of a plurality of identical circular plates 6. The set of plates 7 is pressed together by the two

stationary end plates

4 and 5. Two

bores

8 and 9 are provided in the upper end plate 5 for the supply of one fluid and discharge of the other fluid which are to be brought into heat-exchange relation. These bores are continued in the individual plates 6 of the set of plates 7, and the lower stationary end plate 4 is provided with two equivalent bores 10 and 11. A small bore 12 is provided laterally from the bore 8 to allow fluid to pass into the space 13 formed between the set of plates 7 and the casing 1 of the pressure vessel. The space 13 is thus placed under the operating pressure. In this way the effective stress on the plates 6 is substantially decreased so that, provided there is no great difference in pressure between the two fluids, it is impossible for a high pressure difference to arise between the space 13 and the spaces inside the set of plates 7.

The individual plates 6 are sealed against each other and against the end plates by sealing means 14 so that the two fluids cannot mix. The

end plates

4 and 5 are held firmly on their seals or seatings 16 in the casing 1 of the pressure vessel by means of stud bolts having nuts which at the same time serve to press the set of plates 7 together.

FIGS. 2, 2a, and 2b illustrate a similar plate heat exchanger having a movable end plate (piston). Here again the apparatus comprises two

stationary end plates

4 and 5, having

bores

8, 9, 10 and 11 for the passage of the two fluids, plates 6 forming a set of plates 7 and having sealing means 14 against the outer space 13.

In this embodiment, the

stationary end plates

4 and 5 are shown held in position, by way of example, by means of threaded rings 17 and 18 screwed into the casing 1. O-

rings

19 and 20 or other sealing means are provided between the

end plates

4 and 5 and the casing 1 to seal the inner space of the pressure vessel.

The casing 1 is widened at the top so that it is subdivided into a narrower portion 21 and a wider portion 22, with an annular shoulder 23 between the two portions. A movable stepped end plate (piston) 24 is provided in the pressure vessel, and tits into both the narrower portion 21 and the wider portion 22 of the casing 1. Like the casing, the movable end plate (piston) has a narrower section 25 and a wide-r section 26 having cylindrical outer faces, between which is an annular shoulder 27. Both sections of the movable end plate (piston) 24 are provided with O-

rings

28 and 29 to provide seals against the cylindrical surfaces of

portions

21 and 22 of the casing 1. The movable end plate (piston) 24 has two

bores

30 and 31. Another bore 32 is provided in the Wider portion 22 of the casing 1 immediately above the the shoulder 23 to permit equalization with atmospheric pressure when the movable end plate (piston) 24 moves. A bore 36 through the wider portion of the movable end plate (piston) 24 permits communication between the space above the movable end plate (piston) and the space 13.

A force P which depends on the cross-sectional area of the wider portion 22 perpendicular to the axis, acts downwardly on the movable end plate (piston) 24. The force P acting upwardly on the movable end plate (piston) 24 is less and depends on the smaller cross-sectional area of the narrower portion 21. The resultant force P P presses the set of plates 7 together. This resultant force is also dependent on the pressure of the fluid above the movable end plate (piston). In this way, high pressures may occur in the fluids flowing through the set of plates 7 without the individual plates 6 being overstressed.

In order to provide a fluid seal between the bore 9 in the upper end plate 5 and the bore 31 in the movable end plate (piston) 24, while at the same time permitting relative movement between the two end plates, a tube 33 is rigidly secured in the bore 31. This tube extends into the bore 9 in the upper end plate 5 and is sealed by means of an O-ring 34. The movable end plate (piston) 24 including the tube 33 may therefore move relatively to the upper end plate 5 without the two fluids flowing through the

bores

8 and 9 mixing with each other. There is no connecting tube between the 'bores 8 and 30 because the pressure in this fluid serves as the compressive force on the movable end plate (piston) 24 and also passes through the bore 36 into the space 13.

The arrangement according to FIGURES 2, 2a, and 2b may be used when the rings of plastics are sufliciently strong for use as the seal between the end plates. If the temperature of the fluids is too high, however, the arrangement according to FIGURE 1 is chosen with the use of metallic seals. In this embodiment, the permissible pressure and the operating temperature are dependent solely on the thickness and constructional material of the casing and on the resistance to high temperatures of the seals between the plates. Owing to pressure equalization between the spaces inside the set of plates 7 and the space 13 surrounding the set of plates 7, very high pressures of the order of up to 6000 atmospheres can be withstood.

I claim:

1. In a plate heat exchanger for the exchange of heat between two fluids under high pressure, said heat exchanger consisting of a plurality of circular plates, said circular plates forming a set of plates and being spaced apart from each other, every second of the spaces between said plates being in fluid communication with one of said two fluids, the remainder of said spaces being in fluid communication with the other of said two fluids, the improvement which comprises: arranging said set of plates within a cylindrical vessel, said vessel being closed by a stationary end plate at both the top and bottom, said end plates being provided with inlet and outlet means for said two fiuids, said vessel having a wider portion and a narrower portion, a stepped movable piston having a wider section fitting into said wider portion of said vessel and a narrower section fitting into said narrower portion of said vessel, said movable piston being provided with an inlet for one of said fluids and an outlet for the other fluid, said set of plates being located and pressed together by pressure in said narrower portion of said vessel between said stationary end plate on the top of said vessel and said stepped movable piston, said inlet in said movable piston being in communication with the space between said movable piston and said adjacent stationary end plate on the top of said vessel, and said outlet in said movable piston communicating with said outlet in said adjacent stationary end plate.

2. A plate heat exchanger as claimed in claim 1 which includes a passage in said movable piston which communicates at one end with said space between said movable piston and said adjacent stationary end plate and at the other end with the space surrounding said set of plates within said narrower portion of said vessel.

3. A plate heat exchanger as claimed in claim 1 which includes sealing means between said wider section of said' movable piston and the wall of said wider portion of said vessel and sealing means between said narrower section of said movable piston and said wall of said narrower portion of said vessel.

4. A plate heat exchanger as claimed in claim 1 which includes an orifice through said wall of said vessel adjacent to the junction of said wider and narrower portions of said vessel, one end of said orifice communicating with the atmosphere and the other end communicating with the interior of said wider portion of said vessel.

5. A plate heat exchanger as claimed in claim 1 wherein the communication between said outlet in said movable piston and said outlet in said adjacent stationary end plate is provided by a tube secured Within said outlet in said movable piston and slidable within sealing means in said outlet in said adjacent stationary end plate.

References Cited by the Examiner UNITED STATES PATENTS 1,056,385 3/1913 Walker 165l67 1,325,637 12/1919 Harrison ll67 1,930,879 10/1933 Linderoth et a1 l65166 ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner.

R. E. BACKUS, M. A. ANTONAKAS, c Assistant Examiners.

Claims

1. IN A PLATE HEAT EXCHANGER FOR THE EXCHANGE OF HEAT BETWEEN TWO FLUIDS UNDER HIGH PRESSURE, SAID HEAT EXCHANGER CONSISTING OF A PLURALITY OF CIRCULAR PLATES, SAID CIRCULAPLATES FORMING A SET OF PLATES AND BEING SPACED APARTFROM EACH OTHER, EVERY SECOND OF THE SPACED BETWEEN SAID PLATES BEING IN FLUID COMMUNICATION WITH ONE OF SAID TWO FLUIDS, THE REMAINDER OF SAID SPACES BEING IN FLUID COMMUNICATION WITH THE OTHER OF SAID TWO FLUIDS, THE IMPROVMENT WHICH COMPRISES: ARRANGING SAID SET OF PLATES WITHIN A CYLINDRICAL VESSEL, SAID VESSEL BEING CLOSED BY A STATIONARY END PLATE AT BOTH THE TOP AND BOTTOM, SAID END PLATES BEING PROVIDED WITH INLET AND OUTLET MEANS FOR SAID TWOFLUIDS, SAID VESSEL HAVING A WIDER PORTION AND A NARROW PORTION, A STEPPED MOVABLE PISTON HAVING A WIDER SECTION FITTING INTO SAID WIDER PORTION OF SAID VESSEL AND A NARROWER SECTION FITTING INTO SAID NARROWER PORTION OF SAID VESSEL, SAID MOVABLE PISTON BEING PRVIDED WITH AN INLET FOR ONE OF SAID FLUIDS AND AN OUTLET FOR THE OTHER FLUID, SAID SET OF PLATES BEING LOCATED AND PRESSED TOGETHER BY PRESSURE IN SAID NARROWER PORTION OF SAID VESSEL BETWEEN SAID STATIONARY END PLATE ON THE TOP OF SASID VESSEL AND SAID STEPPED MOVABLE PISTON, SAID INLET IN SAID MOVABLE PISTON BEING IN COMMUNICATION WITH THE SPACE BETWEEN SAID MOVABLE PISTON AND SAID ADJACENT STATIONARY END PLATE ON THE TOP OF SAID VESSEL, AND SAID OUTLET IN SAID MOVABLE PISTON COMMUNICATING WITH SAID OUTLET IN SAID ADJACENT STATIONARY END PLATE.