Wound tube type heat exchanger

Abstract

The coiled tube type heat exchanger comprises a core cylinder, a front end and a rear end are symmetrically arranged at the two ends of the core cylinder, a plurality of heat exchange tube bundle sets are arranged on the peripheral side of the core cylinder in a surrounding mode, the two ends of each heat exchange tube bundle set are fixed to the front end and the rear end respectively, and folded empty areas are arranged between the front end and the core cylinder and between the rear end and the core cylinder respectively. And the two ends of the heat exchange tube bundle set are respectively bent in the hollow folding areas. According to the technical scheme, 1, heat exchange layout is independently formed in each area, the number of tube bundles between the layers is the same, when the tube bundles cannot be evenly distributed in the areas, the maximum difference of the total number of the areas is 1 through staggered partition, and the basically same heat exchange capacity of the areas is guaranteed; 2, by arranging a folded empty area and bending design of the inner-layer tube bundle and the middle tube bundle, the fixing mode of a tube hoop is canceled, and the problems of turbulent flow, failure and the like caused by the use of the tube hoop are avoided; and 3, the bending of the heat exchange tube is a three-dimensional space structure or continuous transition without a straight section, the later bending can influence the deformation data of the first bending due to ductility, the bending area is divided, and the bending area is formed at one time through deformation simulation and test correction, so that the problem of shape memory of the heat exchange tube is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of manufacturing heat exchange components of nuclear island main equipment, and in particular relates to a coiled tube heat exchanger. Background Art

[0002] The heat exchange assembly is the main equipment for discharging the heat generated by the core of a small integrated reactor. It is part of the pressure boundary of the reactor coolant system. The medium outside the tube is the primary reactor coolant, and the medium inside the tube is the secondary feed water. After the secondary feed water is heated by the primary coolant, its outlet forms superheated steam for steam supply or energy required by the back-end power system or supercooled water of a certain temperature for heating or energy required by the terminal. For some large heat exchangers with special structures, when the tube bundle end is positioned and fixed with positioning elements such as pipe clamps, the following problems may occur: 1. The connection is not firm due to improper installation; 2. The different thermal expansion coefficients of the pipe clamp material and the heat exchange tube material lead to loose connection or stress concentration; 3. The pipe clamp is prone to wear when it contacts the heat exchange tube and is impacted, which causes problems in the operation of the heat exchanger and is difficult to detect; 4. When disasters such as earthquakes occur, the pipe clamp is prone to failure and causes harm. In addition, the heat exchange tube is easily thinned and deformed due to factors such as winding and bending during the winding process of the tube bundle, thereby reducing its service life. Summary of the invention

[0003] In view of this, an object of the present invention is to provide a coiled heat exchanger to solve the deficiencies in the prior art.

[0004] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0005] A coiled tube heat exchanger is provided, which includes a core tube, wherein the two ends of the core tube are symmetrically provided with a front end and a rear end, and a plurality of heat exchange tube bundles are arranged around the circumference of the core tube, and the two ends of the heat exchange tube bundles are respectively fixed to the front end and the rear end, and a folding area is respectively provided between the front end and the core tube, and between the rear end and the core tube, and the two ends of the heat exchange tube bundles are respectively bent in the folding areas.

[0006] As described in the coiled tube heat exchanger, wherein the heat exchange tube bundle set comprises an inner tube bundle, an intermediate tube bundle and an outer tube bundle, the intermediate tube bundle is at least one layer, the number of heat exchange tubes in each layer of tube bundle is the same, and the winding directions are opposite.

[0007] As described in the coiled tube heat exchanger, wherein folding areas are respectively provided between the front end and the core tube and between the rear end and the core tube, and both ends of the middle tube bundle and the inner tube bundle are respectively bent in the folding areas.

[0008] As described in the coiled tube heat exchanger, the straight tube section of each layer of tube bundle is evenly divided into n heat exchange areas, and the upper and lower ends correspond to each other, n≥3, n is a natural number, and the number of heat exchange tubes in each heat exchange area is evenly distributed. When it is impossible to evenly distribute the heat exchange tubes in each area, the maximum difference in the total number of heat exchange tubes in each area is 1 through staggered partitioning.

[0009] As described in the coiled tube heat exchanger, wherein the front end and the rear end are respectively provided with connecting pipe holes, the bending points of the inner tube bundle and the middle tube bundle are consistent with the relative positions of the axes of the front and rear connecting pipe holes, and the front and rear end bending modes of the inner tube bundle and the middle tube bundle are consistent to form a straight line when the end of the tube bundle is inserted into the connecting pipe hole.

[0010] As described in the coiled tube heat exchanger, wherein the inner-to-outer spacing between two adjacent layers of the inner tube bundle, the middle tube bundle and the outer tube bundle in the folded area is greater than the inner-to-outer spacing between two adjacent layers outside the folded area.

[0011] As described in the coiled tube heat exchanger, longitudinal reinforcing ribs, circumferential reinforcing ribs and connecting plates are arranged on the circumferential side of the core tube, and pads are provided between the longitudinal reinforcing ribs and the core tube, and the pads, the longitudinal reinforcing ribs and the circumferential reinforcing ribs are fixedly connected to the core tube through the connecting plates.

[0012] As described in the coiled tube heat exchanger, wherein partition plates are arranged at intervals in the folded area, the folded area is divided into areas by the partition plates, and the total number of heat exchange tubes in each area is substantially the same.

[0013] The beneficial effects of the technical solution of the present invention are:

[0014] 1. Each zone forms a separate heat exchange layout, and the number of tube bundles between each layer is the same. When it is impossible to evenly distribute the zones, the maximum difference in the total number of zones can be achieved by staggered partitioning, which ensures that the heat exchange capacity of each zone is basically the same;

[0015] 2. By setting up the folding area and the bending design of the inner tube bundle and the middle tube bundle, the fixing method of the pipe clamp is eliminated, avoiding the problems of turbulence and failure caused by the use of the pipe clamp;

[0016] 3. The bending of the heat exchange tube is a three-dimensional spatial structure or a continuous transition without a straight section. The later bend will affect the deformation data of the earlier bend due to its ductility. The bending area is divided and the bending area is formed once through simulated deformation and test correction, which solves the shape memory problem of the heat exchange tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] To further illustrate the above-mentioned objectives, structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0018] Figure 1This is a schematic diagram of the structure of a coiled tube heat exchanger according to a preferred embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure of the heat exchange tube bundle closing section of a preferred embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the end surface structure of a heat exchange tube bundle assembly according to a preferred embodiment of the present invention;

[0021] In the figure: 1. core tube; 2. front end; 3. folded area; 4. inner tube bundle; 5. middle tube bundle; 6. outer tube bundle; 7. partition plate; 8. longitudinal reinforcement rib; 9. circumferential reinforcement rib; 10. connecting plate; 11. gasket. DETAILED DESCRIPTION

[0022] The terms "invention", "present invention" and "the present invention" used in this specification are intended to refer broadly to all subject matter of this specification and any patent claims below. Statements containing these terms should not be understood to limit the subject matter described herein or to limit the meaning or scope of any patent claim below. In addition, this specification does not attempt to describe or limit the subject matter covered by any claim of any specific component, paragraph, statement or figure of this application. The subject matter should be understood with reference to the entire specification, all drawings and any claims below. The present invention may have other embodiments and be practiced or implemented in other ways. Moreover, it should be understood that the words and terms used herein are for illustrative purposes and should not be considered as limiting.

[0023] The details of the present invention will now be discussed with reference to the accompanying drawings which illustrate the present invention by way of example only. In the accompanying drawings, similar features or components may be marked with the same reference numerals.

[0024] The use of "including," "having," and "comprising" and variations thereof herein is meant to encompass the items listed thereafter and their equivalents and additional items. Although reference may be made to directions such as above, below, upward, downward, rearward, bottom, top, front, rear, etc., in describing the drawings, for convenience, reference is made relative to the drawings. These directions are not intended to literally accept or limit the present invention in any form. In addition, terms such as "first," "second," "third," etc., are used herein for illustrative purposes and are not intended to indicate or imply importance or significance.

[0025] See also Figure 1 As shown, in a preferred embodiment, the coiled tube heat exchanger of the present invention includes a core tube 1, with a front end 2 and a rear end symmetrically provided at both ends of the core tube 1, and a plurality of heat exchange tube bundles are arranged around the circumference of the core tube 1, with the two ends of the heat exchange tube bundles respectively fixed to the front end 2 and the rear end.

[0026] See also Figure 2 , Figure 3As shown, the heat exchange tube bundle set includes an inner tube bundle 4, an intermediate tube bundle 5 and an outer tube bundle 6. The intermediate tube bundle 5 is at least one layer. A folding area 3 is provided between the front end 2 and the core tube 1 and between the rear end and the core tube 1. The two ends of the intermediate tube bundle 5 and the inner tube bundle 4 are bent in the folding area 3 respectively.

[0027] The straight tube section at the end of each tube bundle is evenly divided into n heat exchange areas, and the upper and lower end ends correspond to each other, n≥3, n is a natural number, and the number of heat exchange tubes in each heat exchange area is evenly distributed. When it is impossible to evenly distribute the heat exchange tubes in each area, the maximum difference in the total number of heat exchange tubes in each area is 1 through staggered partitioning.

[0028] Partition plates 7 are arranged at intervals in the hollow area 3. The hollow area 3 is divided by the partition plates 7. The total number of heat exchange tubes in each area is basically the same. The partition plates 7 also strengthen the fixation of the front end 2, the rear end and the core tube 1. The existence of the hollow area 3 increases the space between the layers of the tube bundle, so that the inner tube bundle 4 and the middle tube bundle 5 have enough space to bend, ensuring that there is enough spacing between them, and then ensuring that there is no possibility of collision under certain working conditions and earthquakes without using pipe clamps.

[0029] The front end 2 and the rear end are respectively provided with connecting tube holes. When the heat exchange tube is wound, through the stepped arrangement of each zone, the bending points of the inner tube bundle 4 and the middle tube bundle 5 are consistent with the relative positions of the axes of the front and rear connecting tube holes, and the front and rear end bending methods of the inner tube bundle 4 and the middle tube bundle 5 are consistent, so as to form a straight line when the end of the tube bundle is inserted into the connecting tube hole. Each heat exchange tube is arranged in this way, and the front and rear layout of each zone is maintained consistent, which ensures that the length of each tube bundle in the same partition is consistent, which is conducive to achieving a uniform heat exchange effect.

[0030] The core barrel 1 is provided with longitudinal reinforcing ribs 8, circumferential reinforcing ribs 9 and connecting plates 10 on its circumference. A gasket 11 is provided between the longitudinal reinforcing ribs 8 and the core barrel 1. The gasket 11, the longitudinal reinforcing ribs 8 and the circumferential reinforcing ribs 9 are fixedly connected to the core barrel 1 through the connecting plates 10. Each layer of the tube bundle is fixed on the gasket 11. The contact surface between the connecting plate 10 and the core barrel 1 is processed into a slope shape, so that the installation of the gasket 11 is more convenient and quick, and the gaskets 11 are connected by the connecting plates 10 to further improve their strength.

[0031] During specific implementation, the structural arrangement is carried out according to the overall working condition requirements, so as to form different combinations to meet the purpose of use.

[0032] For example, the uniform arrangement adopted this time, the product is divided into 8 zones as a whole, and the total number of heat exchange tubes in each zone is kept consistent as much as possible (when the uniform distribution cannot be achieved due to quantity reasons, the deviation does not exceed 1 and the distribution is staggered). The distribution of tubes in each layer is as follows:

[0033] district 1 2 3 4 5 6 7 8 Inner Layer 12 13 12 12 13 12 13 12 Middle level 12 12 13 12 12 13 12 13 Outer Layer 13 12 12 13 12 13 12 12 total 37 37 37 37 37 38 37 37

[0034] The inner and outer distances between two adjacent layers of the inner tube bundle 4 , the middle tube bundle 5 and the outer tube bundle in the hollow area 3 are greater than the inner and outer distances between two adjacent layers in the non-hollow area 3 .

[0035] Arrangement method:

[0036] 1. The number of heat exchange tubes and the winding spiral angle are determined according to the working conditions, and the design calculation is carried out according to the heat exchange capacity;

[0037] 2. Divide the area according to the number of heat exchange tubes and arrange the tube holes according to the space spacing;

[0038] 3. Calculate the winding length according to the winding parameters, and determine the step gradient of the heat exchange tube according to the tube hole spacing to ensure that the length of the heat exchange tube in each zone is consistent;

[0039] 4. Determine the core tube length and structural shape according to the winding length and step gradient of the heat exchange tube;

[0040] 5. Determine the bending method and shape according to the space between the center tube and the cylinder;

[0041] 6. The final assembly structure is consistent and meets the requirements of the product.

[0042] The present invention ensures the gap between the heat exchange tubes at the closing end of the heat exchange tube bundle without using a tube clamp, thereby preventing the heat exchange tubes from colliding with each other due to external vibration or their own resilience.

[0043] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A coiled tube heat exchanger, characterized in that: It comprises a core tube, the two ends of which are symmetrically provided with a front end and a rear end, a plurality of heat exchange tube bundles are arranged around the core tube, and the two ends of the heat exchange tube bundles are respectively fixed to the front end and the rear end.

2. The coiled tube heat exchanger according to claim 1, characterized in that: The heat exchange tube bundle set comprises an inner tube bundle, an intermediate tube bundle and an outer tube bundle. The intermediate tube bundle is at least one layer. The number of heat exchange tubes in each layer of tube bundle is the same and the winding directions are opposite.

3. The coiled tube heat exchanger according to claim 2, characterized in that: A folding area is provided between the front end and the core tube, and between the rear end and the core tube, respectively. Both ends of the middle tube bundle and the inner tube bundle are bent in the folding area respectively.

4. The coiled tube heat exchanger according to claim 2 or 3, characterized in that: The straight tube section at the end of each tube bundle is evenly divided into n heat exchange areas, and the upper and lower end ends correspond to each other, n≥3, n is a natural number, and the number of heat exchange tubes in each heat exchange area is evenly distributed. When it is impossible to evenly distribute the heat exchange tubes in each area, the maximum difference in the total number of heat exchange tubes in each area is 1 through staggered partitioning.

5. The coiled tube heat exchanger according to claim 4, characterized in that: The front end and the rear end are respectively provided with connecting pipe holes, the bending points of the inner tube bundle and the middle tube bundle are consistent with the relative positions of the axes of the front and rear connecting pipe holes, and the front and rear end bending modes of the inner tube bundle and the middle tube bundle are consistent to form straight sections that are collinear when the ends of the tube bundles are inserted into the connecting pipe holes.

6. The coiled tube heat exchanger according to claim 4, characterized in that: The inner-to-outer spacing between two adjacent layers of the inner tube bundle, the middle tube bundle and the outer tube bundle in the folded area is greater than the inner-to-outer spacing between two adjacent layers outside the folded area.

7. The coiled tube heat exchanger according to claim 4, characterized in that: The core barrel is provided with longitudinal reinforcing ribs, circumferential reinforcing ribs and connecting plates on its circumferential side, a cushion strip is provided between the longitudinal reinforcing rib and the core barrel, and the cushion strip, the longitudinal reinforcing rib and the circumferential reinforcing rib are fixedly connected to the core barrel via the connecting plates.

8. The coiled tube heat exchanger according to claim 1, characterized in that: Partition plates are arranged at intervals in the folded area, and the folded area is divided into sections by the partition plates, and the total number of heat exchange tubes in each section is substantially the same.

Images