PT2156128E - Heat exchanger shell assembly and method of assembling - Google Patents

Abstract

A heat exchanger shell assembly comprising an outer shell having a nozzle at its lower side; an inner shell member within the outer shell and forming an intermediate space with the outer shell, the inner shell member having an opening at its lower side; wherein the arrangement further comprises a seal member arranged to fit in the intermediate space, the seal member providing a sealed passageway for fluid between the opening and the nozzle, and a method of assembling a heat exchanger shell structure, and a method of assembling a heat exchanger shell structure, comprising sliding an inner shell member into an outer shell, to form an intermediate space, arranging the inner shell member in a lifted position in the outer shell; sliding a seal member into the intermediate space; and lowering the inner shell member so that the gravity force exerted on the seal member acts as sealing force.

Description

ΡΕ2156128 1

DESCRIPTION

" HEAT EXCHANGE HOUSING ASSEMBLY AND MOUNTING METHOD "

Field of the Invention The present invention relates to a housing heat exchanger assembly and to a method of assembling a heat exchanger housing structure.

Background of the Invention

A shell and tube heat exchanger is an indirect heat exchanger. The heat is transferred between a fluid passing through the tubes of a tubular bundle (the side of the tubes) extending in a heat exchanger housing, and a fluid passing through the space outside the tubes (the housing side) . Details of shell heat exchangers and tubes can, for example, be found in Perry's Chemical Engineers' Handbook, 7th edition, 1997, McGraw-Hill Inc., pages 11-33 to 11-46.

The shell and tube heat exchangers can be characterized according to the number of passages to the fluid on the shell side and the side of the tubes. At each passage, the respective fluid flows essentially through the length of the heat exchanger, which is typically horizontally elongated. At multiple passages in the casing, the fluid flow travels a plurality of times back and forth the length of the casing. The heat exchanger housing has inlet and outlet nozzles for the fluid on the side of the housing. For a single pass heat exchanger, an inlet nozzle is typically disposed at one end of the housing, in particular at the top of the housing, and an outlet nozzle is placed at the opposite end, in particular at the bottom. The same is true for an odd number of passages. In the case of two passages (or indeed an even number) the inlet and outlet nozzles are suitably disposed at the same end.

When retrofitting a heat exchanger such as for modified use or for improved performance, it may be desired to adapt the number of passes. For example, if a tubular bundle with transverse supports comprising expanded metal baffles is to be installed, a higher number of casing side passages may be preferred for optimum performance. The expanded metal is produced from sheet metal that is cut and expanded. Expanded metal baffles are for example known from International patent applications Nos. WO 2003/067170, W02005 / 015107 and W02005 / 061982, incorporated herein by reference, and produced for 3 ΡΕ2156128 have significant advantages in practice, such as a lower tendency for scale, lower pressure drop, and improved heat transfer due to turbulence created in the casing fluid. In expanded metal baffles spanning the cross-section of the available casing passage, the fluid flow in the casing is longitudinal. In a conventional heat exchanger using segmental baffles, the fluid coils even with a passageway in the housing along the main flow path in the housing so that the effective length of flow on the housing side is greater than the longitudinal extent of the housing. When expanded metal baffles are used, it is preferred to use a higher number of casing side passages to optimize the length of the flow path in the casing, and this may particularly be done in view of the low pressure drop caused by the baffles of expanded metal. A problem is encountered when the number of passages on the side of the housing is to change between an even number and an odd number, since then one of the nozzles is located in an inadequate manner. In principle, it may be contemplated to prepare an internal flow path for the fluid from the housing side of one end of the housing to the other. It is an object of the invention to provide an arrangement of the heat exchanger housing enabling the number of passageways on the side of the housing to be modified. 4 ΡΕ2156128

Summary of the Invention

To this end the invention provides a heat exchanger housing arrangement comprising an outer casing having a nozzle at its bottom; an inner housing member within the outer housing and forming an intermediate space with the outer housing, the inner housing member having an opening in its lower portion; wherein the arrangement further comprises a sealing member adapted to fit the intermediate space, the sealing member providing a fluid sealed passageway between the aperture and the nozzle.

By the arrangement of the inner housing element, it is possible to direct the fluid from the housing side from one end of the housing to the other using the intermediate space. The space of the inner housing, in which the current heat exchange with a tubular bundle must take place, needs to be sealed against the intermediate space, otherwise the fluid on the side of the housing can flow along a short- reducing the efficiency of heat transfer. A sealing member between the inner housing member and the outer housing is provided for this purpose. Preferably, the sealing member is a gravity sealing member, wherein the sealing force is provided by the force of gravity exerted on the sealing member by the inner housing member. In particular, the sealing member is not connected to at least one of the outer housing elements and 5 ΡΕ2156128 of the inner housing, preferably not connected to both the outer housing and the inner housing elements. This allows particularly easy installation of the housing arrangement since the sealing member can be pushed into the interior space after the inner housing member is disposed in the outer housing member and the seal is simply accomplished by lowering the inner housing so that its weight suitably together with the weight of the tubular bundle exerts a sealing force on the sealing member. Moreover, by not connecting the inner and outer shells via the sealing member, the different temperature expansion between the outer shell and the inner shell elements can be harmonized.

Heat exchangers such as those defined in the preamble of claim 1 are known from BE-A-449817, US-A-2006/0289153, DE-A-102005049067 and NL-A-7212921, none of which discloses a sealed gasket member with a sealed passageway according to the present invention.

In a suitable embodiment, the sealing member is a plate having a top and a bottom surfaces that are disposed to conform to the outer shell and inner shell elements surrounding the nozzle and the aperture, preferably comprising a gasket on the upper surface and / or lower. 6 ΡΕ2156128

In a particular embodiment, the nozzle forms a first nozzle of the outer shell and the aperture forms a first aperture of the inner shell member, the inner shell further comprising a second nozzle and the inner shell member comprises a second aperture, and the second nozzle and the second aperture are arranged to be in fluid communication via the interspace. The invention further provides a method of assembling a heat exchanger, comprising: providing an outer casing having a nozzle at its bottom and an inner casing member having an aperture; sliding the inner housing member into the outer housing to form an intermediate space with the outer housing and to achieve a position in which the opening is above the nozzle; arrangement of the inner housing member in an elevated position in the outer housing; sliding a sealing member into the interspace, the sealing member providing a fluid passageway between the aperture and the nozzle; and lowering the outer housing member so that the force of gravity exerted on the sealing member acts as a sealing force. The method is particularly useful for reconditioning a heat exchanger, wherein the outer shell is maintained and a new tubular bundle is disposed within the inner shell member.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail and with reference to the accompanying drawings, in which: Figure 1 schematically shows a heat exchanger with a heat exchanger housing assembly in accordance with the invention; Figure 2 shows the heat exchanger of Figure 1 in section along the line II-II; Figure 3 schematically shows a top view of the sealing member 25 in Figures 1 and 2.

Where reference numerals when used in different Figures, refer to the same objects or similar objects.

Detailed Description of the Invention Reference is made to Figures 1-3 schematically showing a heat exchanger 1 including a heat exchanger housing assembly 2 or structure according to the invention. The heat exchanger housing assembly ΡΕ2156128 comprises an outer housing 4 and an inner housing member 5. The outer housing 4 has an inlet nozzle 8 (second nozzle) in its upper part and an outlet nozzle 9 (first nozzle 9 ) at the bottom. The inner housing member 5 extends cylindrically between a mirror 12 and a free head 14, thereby forming an intermediate space 16 with the outer housing. The inner housing member has an inlet (second aperture) opening 21 in the out of a plurality of holes around its top near the end opposite the inlet nozzle 8, and an outlet opening 23 (first aperture) in its bottom at the same end. For handling during installation, the inner housing member 5 is preferably provided with longitudinal slide bars 24 on which the inner housing member can slide inside the outer housing 4.

A sealing member 25 is disposed in the intermediate space 16, the sealing member providing a sealed fluid passageway 26 between the outlet opening 23 and the outlet nozzle 9. The sealing member 25 is shown only very schematically in Figure 1 and is best seen in Figures 2 and 3. Its basic structure is formed by an arcuate dish 28 shaped with the outer housing member and the inner housing member. A handle 31 is used for handling the sealing member during installation. The inner housing member is provided with a dish 30 which is welded around the mackerel 23 to form a contact surface for the wiper member.

For optimum sealing, the sealing member is provided with top and bottom sealing rings 32, 33, suitably disposed in a circular groove seat machined in the plate 28 of the sealing member. A suitable sealing material is polytetrafluoroethylene (PTFE) for resistance to temperatures up to 250 degrees C. Good results were obtained with 100% expanded PTFE (e-PTFE), Gore-Tex Series 300 multidirectional oriented fiber structure. The temperature range of this material is between -240 ° C and +250 ° C, with permissible tip temperatures up to 315 ° C. A 3mm thick PTFE tape was used. A sealing tape having a thickness of 2 mm was used for the free head and baffle seals. Before fitting the sealing rings, the seat was cleaned with alcohol and the packing was glued to the base.

Thus, the sealing member 25 is arranged to seal by gravity. It can be loosely introduced into the intermediate space 16 when the inner housing is raised. The sealing force is provided by the force of gravity exerted on the sealing member by the inner housing member, and the sealing is achieved without the sealing member being tightened against any of the housings 4, 5. After installation of the sealing member, the inner housing member does not rest on the sliding straps 10 ΡΕ2156128 in the vicinity of the outlet aperture 23. The inner housing member houses the tubes 35, 36 extending from the tube plate 12 to the free head 14, and the tubes contribute to exerting pressure by the action of the weight on the seal member. The weight may for example be more than 1000 kg such as 5000 kg. A longitudinal baffle 38 with an aperture 39 serves to provide a two-pass configuration on the side of the housing. To mechanically assemble the longitudinal baffle, the inner casing member may be constructed of upper and lower half casings, between which the longitudinal baffle is secured.

Turning now to the side of the heat exchanger tubes 1, only few tubes 35, 36 are shown for the sake of clarity. The tube side of the heat exchanger 31 is indicated with dots. In this embodiment, the side of the pipes has a double-pass arrangement. The tube side has an inlet 41 for an inlet manifold of the tubes 43. The inlet manifold of the tubes is in fluid communication with the underside of the tubular bundle, tubes 36 extending to the tube end mirror 44 attached to the tubing free head 14 which in turn is in fluid communication with the upper part of the tube bundle, tubes 35 which extend to the tube outlet manifold 47 where the tube side outlet 49 is located. The inlet and outlet heads of the tubes 43, 47 are separated by a horizontal plate 51 which extends 11 ΡΕ2156128 horizontally in the lengthwise direction in the center of the outer shell 4 from the end of the shell to the mirror 12 in which the tubes are secured . The mirror is secured to the housing by flanges (not shown) through which the inlet end of the housing can be opened for insertion or removal of internal elements. The flanges through which the end portion of the housing can be removed are also disposed at the rear end near the free head 14. The end mirror 44 at the opposing end also secures the tubes, but unlike the mirror 12, the end mirror 44 and the free head 14 to which it is connected, are not connected to the housing 34, i.e., the end manifold is floating. This allows thermal expansion of the tubes inside the housing. Instead of an end manifold, which receives and distributes all of the fluid from the tubes, separate U-tubes can also be applied.

The tubes are supported by a plurality of transverse baffles 65. They may in particular be expanded metal baffles, but baffles of rods or other baffles may also be applied. In Figure 2, there is shown a metal net 66 which supports the tubes 35 in the upper half. Only few tubes are shown that extend and are supported through windows of the expanded metal frame. Suitably, the tubes 36 in the lower half are supported in the same manner. 12 ΡΕ2156128 The normal operation of the installed heat exchanger 1 will now be discussed. When the heat exchanger is used in a crude oil preheating train in a crude petroleum distillation unit, the tubing side fluid may be crude (cold) oil and the casing side fluid may be long (hot) ) of the crude oil distillation unit. For such an application with considerable risk of inlays, the expanded metal baffles on the side of the casing are advantageous in that they suppress the fouling. The tube side fluid is passed through an aperture 41 and the tube inlet manifold 43 along the tubes 36, and subsequently via the oscillating head 14 through the upper tubular bundle to the outlet manifold 47 and outlet fluid 49. During this passage, it is heated by heat exchange with the fluid on the side of the housing. The hot fluid on the side of the housing is introduced via an inlet nozzle 8 into the outer housing, where it flows through the intermediate space towards the inlet 21 of the inner housing member. This inlet is formed by a plurality of holes spread around the top of the inner housing member. In this way an optimal distribution of the housing fluid is achieved around the tubes 35. The housing side fluid flows into the mirror 12, turns through the aperture 39 and continues toward the outlet 23. From the outlet 23 it passes through the passageway 26 formed by the sealing element 13 ΡΕ2156128 to the outlet nozzle 9, with a lower temperature than the inlet nozzle 8. The lower half of the intermediate space (circular ring) between the outer casing 4 and the inner housing member 5 is filled with a housing fluid which does not flow or flow slowly. This fluid will assume a temperature somewhere close to the inlet temperature on the side of the tubes. Since the sealing member is not interconnected with the outer housing 4 and the inner housing member 5, it may expand thermally differently in response to different temperatures which it will have in the course of operation.

A method of assembling the shell structure 2 of the heat exchanger of Figure 1 will now be discussed. First, the outer shell is provided, not including the end portions of the inlet / outlet pipe manifolds and the free head of so that both longitudinal ends suitably are opened. In the event of a reconditioning, the outer casing of the original heat exchanger is maintained, and new interior elements, typically the tubular bundle and the inner casing, are provided. The mirrors, inlet / outlet manifolds, and free head may need to be replaced . The inner housing member 5, suitably including the tubular bundle, is slid on the slide bars 24 inside the outer housing until the aperture 23 is directly above the outlet nozzle 14 ΡΕ2156128 9. Then the inner housing member is raised sufficiently so that the sealing member can be passed into the intermediate space between the outlet opening 23 and the outlet nozzle 3. The inner housing member is lowered so that the force of gravity exerted on the sealing member acts as a sealing force. Then the heat exchanger can be completed by connecting the end portions with flanges.

If it is required to clean the heat exchanger, it can be broken down in reverse order, cleaned, and reassembled.

Lisbon, June 26, 2012

Claims (6)

A heat exchanger housing assembly (2) comprising an outer housing (4) having a nozzle (9) in its lower portion; an inner housing element (5) within the outer housing and forming an intermediate space (16) with the outer housing (4), the inner housing element (5) having an opening (23) at its bottom; wherein the heat exchanger housing assembly further comprises a sealing member (25) adapted to fit into the intermediate space (16), characterized in that the sealing member (25) provides a sealed passageway (26 ) to a fluid between the aperture (23) and the nozzle (9). A heat exchanger housing assembly (2) according to claim 1, characterized in that the sealing member (25) is a gravity sealing member, wherein the sealing force is supplied by the force of the sealing member gravity exerted on the seal member (25) by the inner housing member (5). Heat exchanger housing assembly according to claim 1 or 3, characterized in that the sealing element (25) is not, during normal operation, connected to at least one of the outer housing element (4), and the inner carcass element (2) ΡΕ2156128 (5) is preferably not connected to both the outer housing element (4) and the inner housing element (5). A housing heat exchanger assembly according to any one of claims 1-3, characterized in that the sealing member (25) is a dish (28) having upper and lower surfaces which are arranged to conform with the outer housing and inner housing members surrounding the mouthpiece and the aperture, preferably comprising a gasket on the upper surface and / or the lower surface. A heat exchanger housing assembly according to any one of claims 1-4, characterized in that the nozzle forms a first nozzle (9) and wherein the aperture forms a first aperture (23), the outer shell (4) further comprising a second nozzle (8) and the inner housing member (5) comprising a second aperture (21), and wherein the second nozzle (8) and the second aperture (21) are arranged to be in communication through the intermediate space (16). A method of assembling a heat exchanger shell structure, comprising: providing an outer shell (4) having a nozzle (9) in its lower part and an inner shell element (3) having an aperture (23); sliding the inner housing member 5 into the outer housing 4 to form an intermediate space 16 with the outer housing 4 and reaching a position in which the aperture 23 is above the nozzle 9 ); arrangement of the inner housing member (5) in an elevated position in the outer housing (4); sliding a sealing member 25 into the intermediate space 16, the sealing member 25 providing a fluid passageway between the aperture 23 and the nozzle 9; and lowering the inner housing member (5) so that the force of gravity exerted on the sealing member (25) acts as a sealing force. Lisbon, June 26, 2012