EA016175B1 - 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 me

Description

The shell-and-tube heat exchanger is an indirect heat exchanger. Heat is transferred between the fluid passing through the tube bundle (in-pipe zone) located in the heat exchanger housing and the fluid passing outside the tubes (inter-tube zone). Details regarding shell-and-tube heat exchangers can be found, for example, in the Rettu'k S11st1sa1 Epscheetk 'Napboook manual, 7th edition, 1997, publisher MsOta ^ -NS 1ps., P. from 11-33 to 11-46.

Shell-and-tube heat exchangers differ in the number of fluid passages in the annulus and in-annulus. In each passage, the corresponding fluid flows essentially along the entire length of the heat exchanger, which is usually elongated in the horizontal direction. In multi-pass housings, the fluid flow bends several times forward and backward along the length of the housing.

The heat exchanger housing contains an inlet and outlet nozzles for the fluid of the annulus. In a heat exchanger with a single-pass annular zone, the inlet pipe is usually located at one end of the housing, in particular in its upper part, and the exhaust pipe is located at the opposite end, in particular in its lower part. The same is true for any odd number of passes. In the case of a two-pass out-of-pipe zone (or, in fact, for any even number of passes), the inlet and outlet nozzles are respectively located at the same end of the housing.

When converting a heat exchanger, for example, for another use or to increase efficiency, a change in the number of passes may be required. For example, if it is necessary to install a tube bundle with transverse supports containing partitions of a metal mesh, then for optimal efficiency there may preferably be a larger number of passages in the annulus. The metal mesh is made of sheet metal, which is cut into narrow strips and stretched. Partitions of metal mesh are described, for example, in documents XVO 2003/067170, \ UO 2005/015107 and νθ 2005/061982, incorporated by reference. In practice, these baffles have significant advantages, such as less tendency to oiling, less pressure drop and improved heat transfer due to the swirl created in the annular fluid. In the partitions of the metal mesh, overlapping the cross section of the accessible passage of the housing, the flow of fluid in the annular zone occurs in the longitudinal direction. In conventional heat exchangers that use segmented baffles, the flow bends even with one pass in the annulus along the main flow path in the housing, so that the effective flow length in the annulus is greater than the length of the housing in the longitudinal direction. When using partitions from a metal mesh, it is preferable to use a larger number of passages in the annular zone in order to optimize the length of the flow path in the housing. In particular, this can be done with a small pressure drop caused by partitions from a metal mesh.

The problem arises when the number of passes in the annular zone must be changed from even to odd or vice versa, since in this case one of the nozzles turns out to be inappropriately positioned. In principle, it is possible to form an internal path for the flow of fluid in the annulus from one end of the housing to the other. The objective of the invention is to create a housing of a heat exchanger, which allows you to change the number of passes in the annular zone.

Disclosure of invention

This problem is solved in a heat exchanger housing containing, according to the invention, an outer shell, on the lower side of which a pipe is located, and an inner shell with an opening on the lower side, located in the outer shell and forming an intermediate space with it, while the housing further comprises a sealing element made with the ability to install in the intermediate space and forming a sealed channel for fluid between the hole and the pipe.

The presence of the inner shell allows you to direct the fluid of the annular zone from one end of the housing to the other through the intermediate space. The internal space of the housing, in which heat exchange with the tube bundle actually takes place, must be sealed relative to the intermediate space, since otherwise the annular fluid can flow along a shortened path, reducing the heat transfer efficiency. For this purpose, a sealing element located between the inner and outer shells is intended. Preferably, the sealing element is such a sealing element in which the sealing force acting on it is provided by gravity applied to it from the side of the inner shell. In particular, the sealing element is not connected to the outer shell and / or to the inner shell, preferably it is not connected to either the outer or inner shells. This, in particular, makes it easy to install the housing, since the sealing element can be pushed into the intermediate space after the inner shell is located in the outer shell, and the sealing is carried out by simply lowering the inner shell, so that its weight together with the weight of the tube bundle acts as a sealing force on sealing element. In addition, the lack of compound internal and

- 1 016175 of the outer shells through the sealing element allows you to adapt to different thermal expansion of the outer and inner shells.

In an advantageous embodiment of the invention, the sealing element is a plate with upper and lower surfaces that correspond to the outer and inner shells and surround the nozzle and the hole, and preferably the sealing element comprises a gasket on the upper and / or lower surfaces.

In a specific embodiment, the nozzle is a first nozzle of the outer shell, and the hole is a first hole in the inner shell, the outer shell additionally contains a second nozzle, and a second hole is made in the inner shell, while the second nozzle and the second hole communicate with each other through intermediate space.

In addition, the invention relates to a method for assembling a heat exchanger, comprising the steps of: installing an outer shell, on the lower side of which a pipe is located, and installing an inner shell with an opening;

pushing the inner shell into the outer one to form an intermediate space between them and achieve a position in which the hole is located above the nozzle;

positioning the inner shell in a raised position in the outer shell;

pushing the sealing element into the intermediate space, while the sealing element forms a channel for the fluid between the hole and the pipe; and lowering the inner shell, so that the force of gravity acting on the sealing element performs the function of the sealing force.

This method is especially useful for retrofitting a heat exchanger when the outer shell is retained and a new tube bundle is placed in the inner shell.

Brief Description of the Drawings

In FIG. 1 schematically shows a heat exchanger with a housing according to the invention;

in FIG. 2 is a section along ΙΙ-ΙΙ in FIG. one;

in FIG. 3 - sealing element 25 shown in FIG. 1 and 2, plan view.

In the drawings, the same or similar elements are denoted by the same reference numerals.

The implementation of the invention

In FIG. 1-3, a heat exchanger 1 comprising a housing 2 is shown schematically. The heat exchanger housing 2 comprises an outer shell 4 and an inner shell 5. An inlet pipe 8 (second pipe) is located on the upper side of the outer shell 4, and an outlet pipe 9 (first one on its lower side) branch pipe). The inner shell 5 in the form of a cylinder is located between the tube sheet 12 and the floating cover 14, forming together with the outer shell an intermediate space 16. The inner shell has an inlet 21 (second hole) in the form of many holes located around the upper side of the inner shell near the end opposite inlet pipe 8, and has an outlet 23 (first hole) located on the lower side of the inner shell at the same end. For movement during installation, the inner shell 5 preferably comprises longitudinal guides 24 along which the inner shell can be slid into the outer shell 4.

In the intermediate space 16 there is a sealing element 25, forming between the outlet 23 and the outlet 9 a sealed fluid channel 26.

In FIG. 1, the sealing element 25 is shown very schematically, and in FIG. 2 and 3, he is depicted in more detail. The sealing element 25 is formed by a curved plate 28 corresponding to the outer and inner shells. There is a handle 31 for moving the sealing element during installation. The inner shell is provided with a plate 30 that is welded around the outlet 23 and forms a contact surface for the sealing element.

For optimal sealing, the sealing element is provided with upper and lower gasket rings 32 and 33, which are located in their respective seats in the form of annular grooves made in the plate 28 of the sealing element. A suitable cushioning material, due to heat resistance reaching up to 250 ° C, is polytetrafluoroethylene (PTFE). Good results are obtained with 100% stretched PTFE with a multidirectional structure of an oriented fiber, such as Oote-Tech Series 300. The temperature range of this material is from -240 to 250 ° C, with allowable peak temperatures reaching 315 ° C. A 3 mm thick PTFE tape is also used. To seal the floating cover and the baffle, a 2 mm thick sealing tape is used. Before placing the spacer rings, the seat is cleaned with alcohol and the gasket is glued to the seat.

The sealing element 25 performs a seal using gravity. It can be freely placed in the intermediate space 16 with the inner shell raised. The sealing force is provided by the force of gravity acting on the sealing element from the side

- 2 016175 inner shell, the seal is achieved without fastening the sealing element to one of the shells 4 and 5. After installing the sealing element, the inner shell does not rest on the guides 24 near the outlet 23.

In the inner shell between the tube sheet 12 and the floating cover 14 there are tubes 35 and 36, the weight of which also presses on the sealing element. This weight may be, for example, more than 1000 kg, in particular 5000 kg. For the formation of a two-pass design of the annular zone there is a longitudinal partition 38 with a hole 39. For the installation of the longitudinal partition, the inner shell can be made of two halves - the upper and lower, between which the longitudinal partition is clamped.

Next, the in-pipe zone of heat exchanger 1 will be considered. For clarity, only a few tubes 35 and 36 are shown. The in-pipe zone of heat exchanger 1 is indicated by dots. In this embodiment, the in-pipe zone has a tubular two-pass structure. The in-pipe zone comprises an inlet pipe 41 leading to the inlet manifold 43. The inlet manifold is in communication with the bottom of the tube bundle, the tubes 36 reaching the end of the tube 44 connected to the floating cover 14. The floating cover 14 is in communication with the upper part of the tube bundle, this tube 35 reaches the exhaust manifold 47, where the exhaust pipe 49 is located, leading from the in-pipe zone. The intake and exhaust manifolds 43 and 47 are separated by a horizontal plate 51 located horizontally in the center of the outer shell 4 from its end to the tube sheet 12 in which the tubes are fixed. The tube sheet is attached to the housing by means of flanges (not shown) through which the inlet end of the housing can be opened to insert or remove internal elements. At the rear end, adjacent to the floating cover 14, flanges may also be located through which the end portion of the housing can be removed.

An end tube 44 located at the opposite end also holds the tubes, but unlike the tube 12, the end tube 44 and the floating cover 14 to which the end tube 44 are attached are not attached to the sheath 4, i.e. end collector is not fixed. This allows the tubes to expand thermally inside the housing. Instead of an end collector that receives and distributes the entire fluid flowing through the tubes, separate I-shaped tubes can also be used.

The tubes are supported by several transverse partitions 65. In particular, the partitions can be made in the form of metal nets, rods, or other partitions can be used. In FIG. 2 shows a grid 66 of metal mesh that supports tubes 35 in the upper half of the housing. In this case, only a few tubes are shown that pass through the holes in the metal mesh and rest on it. It is advisable that the tubes 36 of the lower half are supported similarly.

The heat exchanger 1 operates as follows.

When a heat exchanger is used in a preheating chain of a crude oil distillation unit, the fluid in the in-pipe zone can be (cold) crude oil, and the fluid in the in-pipe zone can be (hot) fuel oil coming from the crude oil distillation unit. For such an application with a significant risk of oiling, it is advisable to have partitions from the metal mesh in the annular zone, since they weaken the oiling. The fluid of the in-pipe zone passes through the inlet pipe 41 and the inlet manifold 43, along the tubes 36 and then through the floating cover 14 to the top of the tube bundle to the exhaust manifold 47 and the outlet pipe 49. During this movement, it is heated due to heat transfer from the annular fluid .

The hot fluid of the annular zone enters through the inlet pipe 8 into the outer shell, where it flows along the intermediate space towards the inlet 21 of the inner shell. This entrance is made in the form of many holes distributed over the upper part of the inner shell. As a result, optimal distribution of fluid through the tubes 35 is achieved. The annulus fluid flows towards the tube sheet 12, unfolds in the hole 39 and continues to flow towards the outlet 23. From the outlet 23, it enters through a channel 26 formed by a sealing element , in the exhaust pipe 9, while its temperature is less than the temperature that was in the inlet pipe 8.

The lower half of the intermediate space (ring) between the outer and inner shells 4 and 5 is filled with a stationary or slowly flowing fluid of the annulus. The temperature of this fluid is approximately equal to the temperature at the inlet of the in-pipe zone. Since the sealing element does not connect the outer shell 4 with the inner one, they expand differently under the influence of different temperatures that they have when the device is operating.

The housing 2 of the heat exchanger shown in FIG. 1 is assembled as follows.

First, the outer shell is installed without the end parts of the intake / exhaust manifold and the floating cover, i.e., both longitudinal ends of the outer shell are open. In the case of conversion, the outer shell of the original heat exchanger is maintained and new internal elements are installed, usually a bundle of tubes and an inner shell. Pipe grills, intake / exhaust manifolds

- 016175 tori and floating cover may require modification or replacement. The inner shell 5 and the tube bundle are pushed along the guides 24 into the outer shell to the hole 23, which is located directly above the outlet pipe 9. Next, the inner shell is lifted so that the sealing element can pass into the intermediate space between the outlet 23 and the outlet pipe 9. Next, the inner the shell is lowered, so that the force of gravity acting on the sealing element, performs the function of the sealing force. Then, fastening the end parts with flanges, complete the assembly of the heat exchanger.

If it is necessary to clean the heat exchanger, it can be disassembled in the reverse order, cleaned and reassembled.

Claims (6)

CLAIM 1. A heat exchanger housing containing an outer shell, on the underside of which there is a nozzle, and an inner shell for the first medium with a hole on its underside, located in the outer shell and forming together with it an intermediate space for the second medium, while the housing further comprises a sealing the element is made with the possibility of installation in the intermediate space and forming between the hole and the pipe a sealed channel for the fluid. 2. The heat exchanger housing according to claim 1, in which the sealing force acting on the sealing element is provided by gravity applied to it from the inner shell. 3. The heat exchanger housing according to any one of claims 1 or 2, in which, during normal operation, the sealing element is not connected to the outer shell and / or the inner shell, and preferably neither with the outer nor with the inner shell. 4. The heat exchanger housing according to any one of claims 1 to 3, in which the sealing element is a plate with upper and lower surfaces corresponding to the outer and inner shells and the surrounding pipe and hole, and the sealing element preferably contains a gasket on the upper and / or lower surfaces . 5. The heat exchanger housing according to any one of claims 1 to 4, in which the nozzle is the first nozzle and the hole is the first hole, the outer shell further comprises a second nozzle, and the inner sheath is the second hole, the second nozzle and the second hole communicating among themselves through an intermediate space. 6. The method of assembling the body of the heat exchanger according to claim 1, comprising the steps in which the inner shell is pushed into the outer shell to form an intermediate space between them to the position in which the hole is located above the nozzle; have the inner shell in the outer shell in a raised position; pushing the sealing element into the intermediate space so that the sealing element forms a fluid channel between the opening and the nozzle; lower the inner shell so that the force of gravity acting on the sealing element performs the function of the sealing force.