A hierarchical opening flow guide end structure for a shell-and-tube heat exchanger

Abstract

The application discloses a kind of hierarchical open flow guide head structure for shell-and-tube heat exchanger, for solving the technical problems such as the machining difficulty of existing flow guide head structure is larger, flow improvement effect is limited, structure is complex etc..The flow guide head structure includes inlet pipe, head cover, flow guide assembly and tube sheet;The head cover is hemispherical structure, which is connected with tube sheet and encloses flow guide area;Inlet pipe is installed on the side wall of head cover, and is communicated with flow guide area;The central axis of inlet pipe is perpendicular to the plane where tube sheet is located;Flow guide assembly includes inner flow guide assembly and outer flow guide assembly arranged near inlet pipe in flow guide area.The flow guide head structure of the application can distribute the incoming flow three times, thereby greatly improving the flow distribution of head area, with the advantages of simple structure, small resistance, easy installation, low cost and high feasibility, etc., and can be used to improve the flow distribution of most industrial shell-and-tube heat exchanger tube side head.

Description

TECHNICAL FIELD

[0001] The present application relates to a heat exchanger head structure, in particular to a hierarchical opening flow guide head structure for a shell-and-tube heat exchanger. BACKGROUND

[0002] The heat exchanger is a key heat exchange equipment in industrial thermal process, and the shell-and-tube heat exchanger is widely used in energy, petroleum, chemical industry, metallurgy and aerospace and other industrial fields due to its mature technology, simple structure, low cost, wide flow cross section and easy cleaning of scale.

[0003] The shell-and-tube heat exchanger includes two parts of tube side and shell side, and the heat exchange process of the tube side is greatly affected by the head structure. Unreasonable design of the head structure can easily cause uneven flow between the tube bundles of the tube side, thereby reducing the effective heat exchange area of the shell-and-tube heat exchanger and causing uneven distribution of the internal temperature field, so that the actual operation effect of the shell-and-tube heat exchanger is lower than the design target or even the operation requirement. Therefore, how to reasonably design the head structure of the shell-and-tube heat exchanger to improve the flow distribution characteristics between the tube bundles of the tube side has always been the key breakthrough direction of the design of the shell-and-tube heat exchanger.

[0004] The research results show that the main reason for the flow unevenness caused by the head of the tube side of the shell-and-tube heat exchanger is that the cross-sectional area difference between the inlet pipe and the tube bundle is large, so that most of the flow directly impacts the tube bundle area opposite to the inlet pipe, causing a large flow distribution in this area, while the flow in the surrounding area is relatively small. In order to improve the flow distribution in this head area, a suitable flow guide structure is generally added in the head area.

[0005] Chinese patent with publication number CN114963840A discloses a plate heat exchanger conda flow guide head, the shape of the head shell and the shape of the layered flow guide plate are both based on conda effect, so that the fluid working medium flows to the heat exchanger core channel by itself, but the shape of the flow guide plate needs to be processed according to a specific curve and the number is relatively large, which is relatively complex and difficult to process.

[0006] Chinese patent with publication number CN102967170A discloses a plate-fin heat exchanger flow guide wing head, two flow guide wing pieces are symmetrically installed in the head melon skin structure, and small holes are distributed on the flow guide wing pieces. When the fluid from the inlet pipe of the heat exchanger passes through the flow guide wing head, the fluid is first distributed for the first time at the junction of the inlet pipe and the melon skin structure, and then the fluid on both sides is distributed for the second time when encountering the small holes of the flow guide wing, thereby effectively improving the fluid distribution. However, this structure completely relies on the pre-flow of the flow guide plate and the secondary flow of the small holes of the flow guide wing, ignores the wake effect after the flow guide plate, and has limited improvement effect, and only considers two flow guide plate structures, so the flow improvement effect of the head of the large heat exchanger is limited.

[0007] Chinese patent CN117968439A discloses a heat exchanger flow equalization seal head and its design method, which adopts a multi-layer distribution cavity inner member, so that the seal head has a complex flow guide structure, realizing multiple distribution of the fluid entering the seal head, and thereby improving the uniformity of the fluid flow in the heat exchanger. However, the multi-layer distribution cavity of this structure has a relatively complex structure, which is difficult to operate for large heat exchangers, and the multi-layer distribution cavity also adds a great flow resistance loss, thereby increasing the energy consumption of the heat exchanger seal head. SUMMARY

[0008] The purpose of the present application is to provide a hierarchical opening flow guide seal head structure for a shell-and-tube heat exchanger, which solves the technical problems of the existing flow guide seal head structure, such as difficult to process, limited flow improvement effect, and complex structure.

[0009] To achieve the above purpose, the technical solution of the present application is as follows:

[0010] A hierarchical opening flow guide seal head structure for a shell-and-tube heat exchanger, characterized in that it comprises an inlet pipe, a seal head cover, a flow guide assembly, and a tube sheet.

[0011] The seal head cover is a hemispherical structure coaxially connected with the tube sheet and enclosing a flow guide area. The inlet pipe is installed on the side wall of the seal head cover and communicates with the flow guide area. The central axis of the inlet pipe is perpendicular to the plane of the tube sheet.

[0012] The flow guide assembly comprises an inner flow guide assembly and an outer flow guide assembly arranged near the inlet pipe in the flow guide area. The inner flow guide assembly comprises two inner flow guide plates symmetrically arranged in an eight-shaped manner and respectively installed on the inner wall of the seal head cover. The symmetry plane of the two inner flow guide plates is perpendicular to the tube sheet and coincides with the center plane of the inlet pipe. The two ends of the two inner flow guide plates are respectively spaced from the inlet pipe and the tube sheet. The distance between the two ends of the two inner flow guide plates is less than the distance between the other two ends.

[0013] The outer flow guide assembly comprises two outer flow guide plates symmetrically arranged in an eight-shaped manner on both sides of the symmetry plane and respectively installed on the inner wall of the seal head cover. The two outer flow guide plates are located on the side of the two inner flow guide plates away from the symmetry plane. The two ends of the two outer flow guide plates are respectively spaced from the inlet pipe and the tube sheet. The distance between the two ends of the two outer flow guide plates is less than the distance between the other two ends. The inner flow guide plates and the outer flow guide plates are respectively uniformly distributed with a plurality of flow guide holes, and the mapping length of the inner flow guide plates and the outer flow guide plates on the symmetry plane is equal and coincides.

[0014] Furthermore, the angle α1 between each inner guide plate and the symmetry plane is 20° to 40°. This angle can ensure that the fluid diversion is relatively uniform. If the angle is too large, the pressure on the inner guide plate will be too high, thereby affecting the diversion effect. If the angle is too small, the diversion effect is not obvious.

[0015] Furthermore, the angle α2 between each of the outer guide plates and the symmetry plane is 50° to 70°. This angle can ensure that the fluid diversion is relatively uniform. If the angle is too large, the pressure on the inner guide plate will be too high, thereby affecting the diversion effect. If the angle is too small, the diversion effect is not obvious.

[0016] Furthermore, the vertical distance between the plane where the inner and outer guide plates are located close to the inlet pipe end and the outlet end face of the inlet pipe is recorded as d1; the mapped length of the inner and outer guide plates on the symmetry plane is recorded as d2; the vertical distance between the plane where the inner and outer guide plates are located close to the tube sheet end and the tube sheet is recorded as d3; then d1, d2, and d3 satisfy d1:d2:d3=1:4:5.

[0017] Furthermore, the distance between the two inner guide plates near one end of the inlet pipe is recorded as d4; the distance between the adjacent inner guide plates and the outer guide plate near one end of the inlet pipe is recorded as d5; d4 and d5 satisfy the requirement of evenly dividing the flow section of the inlet pipe into 5 equal parts.

[0018] Furthermore, the opening rate of the inner guide plate and the outer guide plate is 10% to 20%. The diversion effect is best under this opening rate. If there are fewer openings, it is easy to cause the guide plate itself to be under excessive pressure. If there are more openings, the strength of the guide plate will be insufficient, thereby affecting the diversion effect.

[0019] Furthermore, the thickness of the inner guide plate and the outer guide plate are both 5-10 mm. If the thickness is too thin, the strength of the guide plate is poor. If the thickness is too thick, the quality of processing and welding is affected, thereby affecting the diversion effect.

[0020] Furthermore, the tube plate includes a mounting plate and a plurality of heat exchange tubes evenly distributed on the mounting plate and connected to the guide area.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention's graded perforated flow guide head structure for a shell-and-tube heat exchanger employs a flow guide assembly positioned near the inlet pipe in the flow guide area. The flow guide assembly is subdivided into two symmetrically arranged inner and outer flow guide plates, both of which are perforated plates. This structure allows for automatic distribution of incoming flow during its flow. The present invention's flow guide head structure is simple and significantly improves flow diversion and flow uniformity.

[0023] 2. The present invention is used for a graded perforated flow guide head structure for a shell and tube heat exchanger. The angle α1 between the inner flow guide plate and the symmetry plane is 20° to 40°, and the angle α2 between the outer flow guide plate and the symmetry plane is 50° to 70°. This angle design can reduce the resistance of the incoming flow to the corresponding flow guide plate, thereby improving the diversion effect.

[0024] 3. The present invention is used for a graded perforated flow guide head structure of a shell and tube heat exchanger, which reasonably distributes the distance between the inner and outer flow guide plates, as well as the distance between the inner and outer flow guide plates and the inlet pipe and tube sheet, so that it can achieve three-way uniform flow distribution, thereby improving the uniformity of the incoming flow in the guide area.

[0025] 4. The present invention is used for the graded perforated flow guide head structure of the shell and tube heat exchanger, and the processing opening rate is designed to be 10% to 20%, thereby ensuring that the corresponding guide plate achieves the best diversion effect under the premise of having sufficient strength.

[0026] 5. The present invention is used for the graded perforated flow guide head structure of the shell and tube heat exchanger. The thickness of the inner and outer flow guide plates are both 5 to 10 mm, which not only reduces the difficulty of processing and installation, but also improves the diversion effect.

[0027] 6. The graded perforated flow guide head structure for shell and tube heat exchangers of the present invention does not require special materials and processing techniques, has low manufacturing cost, and has obvious cost advantages.

[0028] 7. The graded perforated flow guide head structure for shell and tube heat exchangers of the present invention can adjust the structural dimensions according to the application scenario and is applicable to all types of shell and tube heat exchangers, with a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a structural schematic diagram of an embodiment of a graded perforated flow guide head structure for a shell and tube heat exchanger.

[0030] Figure 2 The present invention is a schematic structural diagram of an inner guide plate and an outer guide plate in an embodiment of a graded perforated guide head structure for a shell and tube heat exchanger.

[0031] Figure 3 The figure is a schematic diagram of the distribution state of each guide plate in an embodiment of a graded perforated guide head structure for a shell and tube heat exchanger of the present invention.

[0032] Figure 4 for Figure 3 AA section view.

[0033] Figure 5This is a flow field comparison diagram of the head area before and after the graded perforated flow guide head structure is used in an embodiment of the present invention for a shell and tube heat exchanger.

[0034] The reference numerals are as follows:

[0035] 1-inlet pipe, 2-head cover, 3-tube sheet, 4-inner guide plate, 5-outer guide plate, 6-mounting plate, 7-heat exchange tube. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] See also Figure 1 and Figure 2 Based on the flow distribution characteristics on the tube side of a shell-and-tube heat exchanger, this embodiment provides a graded perforated flow guide head structure for a shell-and-tube heat exchanger. This structure is designed to improve the flow distribution characteristics in the head area, thereby achieving increased flow uniformity across the tube bundle. The flow guide head structure includes an inlet pipe 1, a head cover 2, a flow guide assembly, and a tube sheet 3.

[0038] The head cover 2 is a hemispherical structure that is coaxially connected to the tube sheet 3 and encloses a flow guide area. The tube sheet 3 includes a mounting plate 6 and a plurality of heat exchange tubes 7 evenly distributed on the mounting plate 6 and connected to the flow guide area. The inlet pipe 1 is mounted on the side wall of the head cover 2 and connected to the flow guide area. The inlet pipe 1 is a cylindrical tubular structure with its central axis perpendicular to the plane of the tube sheet 3. The flow guide assembly includes an inner flow guide assembly and an outer flow guide assembly that are arranged in the flow guide area near the inlet pipe 1. The incoming flow entering through the inlet pipe 1 reaches the tube sheet 3 under the action of the tertiary flow distribution of the flow guide assembly, thereby achieving a more uniform flow state.

[0039] The internal flow guide assembly includes two internal flow guide plates 4 symmetrically arranged in an "eight" shape and mounted on the inner wall of the head cover 2. Their symmetry planes are perpendicular to the tube sheet 3 and coincide with the midplane of the inlet tube 1. A distance is left between the inlet tube 1 and the tube sheet 3 at each end of the two internal flow guide plates 4. Furthermore, the distance between the ends of the two internal flow guide plates 4 closest to the inlet tube 1 is smaller than the distance between the other ends. In this embodiment, the angle α1 between the two internal flow guide plates 4 and the symmetry planes is 20° to 40°, with 30° being the optimal flow diversion angle.

[0040] The external flow guide assembly includes two external flow guide plates 5 symmetrically arranged in an "eight" shape on either side of the symmetry plane and mounted on the inner wall of the head cover 2. The two external flow guide plates 5 are located on the side of the two internal flow guide plates 4 away from the symmetry plane. A distance is left between the ends of the two external flow guide plates 5 and the inlet pipe 1 and the tube sheet 3. Furthermore, the distance between the ends of the two external flow guide plates 5 closest to the inlet pipe 1 is smaller than the distance between the other ends. In this embodiment, the angle α2 between the external flow guide plates 5 and the symmetry plane is 50° to 70°, with 60° being the optimal diversion angle.

[0041] As described above, the inner guide plate 4 and the outer guide plate 5 are both installed by directly welding them to the head cover 2 , which is easy to process and has a firm structure.

[0042] See also Figure 3 In this embodiment, the mapped lengths of the inner and outer guide plates 4, 5 on the symmetry plane are equal and overlap. That is, the distances between the ends of the inner guide plate 4 and the inlet pipe 1 and the tube sheet 3, respectively, are equal to the distances between the ends of the outer guide plate 5 and the inlet pipe 1 and the tube sheet 3, respectively. The vertical distance between the plane containing the ends of the inner and outer guide plates 4, 5 closest to the inlet pipe 1, and the outlet end face of the inlet pipe 1 is defined as d1; the mapped lengths of the inner and outer guide plates 4, 5 on the symmetry plane are defined as d2; and the vertical distance between the plane containing the ends of the inner and outer guide plates 4, 5 closest to the tube sheet 3, and the tube sheet 3 is defined as d3. The optimal flow diversion effect is achieved when d1, d2, and d3 satisfy the formula d1:d2:d3 = 1:4:5.

[0043] Generally, the spacing between the guide plates is determined by the ratio of the area of ​​the inlet flow area cut by the front section of the guide plate to the cross-sectional area of ​​the tube bundle mapped to the tube sheet 3 at the rear end. The distance between two inner guide plates 4 close to the inlet pipe 1 is defined as d4; the distance between adjacent inner guide plates 4 and outer guide plates 5 close to the inlet pipe 1 is defined as d5; see Figure 4 The structural design of this embodiment enables d4 and d5 to evenly divide the flow cross section of the inlet pipe 1 into 5 equal parts, thereby ensuring that the incoming flow is evenly diverted and achieving the best diversion effect.

[0044] In this embodiment, the inner guide plates 4 and outer guide plates 5 are both perforated plates (i.e., multiple guide holes are evenly distributed on each of the inner guide plates 4 and outer guide plates 5). The perforated plates are generally 5 to 10 mm thick, and the porosity of the inner guide plates 4 and outer guide plates 5 is 10% to 20%. The porosity is the ratio of the sum of the areas of all the guide holes on a guide plate to the area of ​​the corresponding guide plate. In addition, in this embodiment, the diameter of the guide holes on the inner guide plates 4 and outer guide plates 5 is generally 10% to 15% larger than the thickness of the corresponding inner guide plates 4 and outer guide plates 5, thereby achieving optimal processing performance and diversion effect of the inner guide plates 4 and outer guide plates 5.

[0045] CombineFigures 1 to 3 The specific process of the flow guide head structure of this embodiment performing three-way flow distribution on the incoming flow is as follows:

[0046] (1) The incoming flow enters the guide area through the inlet pipe 1. First, under the action of the inner guide assembly and the outer guide assembly, the first flow pre-distribution is achieved. In this embodiment, the incoming flow can be divided into five equal parts under the action of the inner guide plate 4 and the outer guide plate 5.

[0047] (2) The incoming flow after the first distribution reaches the surfaces of the corresponding inner guide plate 4 and outer guide plate 5 in sequence, and realizes the second flow distribution under the action of the guide holes on the corresponding inner guide plate 4 and outer guide plate 5.

[0048] (3) Since the inner guide plate 4 and the outer guide plate 5 are both spaced apart from the tube sheet 3, the incoming flow after two flow distributions is distributed for the third time at the corresponding inner guide plate 4 and the outer guide plate 5 at the end close to the tube sheet 3 under the action of the tail flow.

[0049] See also Figure 5 Taking a shell-and-tube heat exchanger structure as an example, after the fluid enters the flow guide area of ​​the heat exchanger head from the inlet pipe 1, it begins to split at the front end of the inner and outer guide plates 4 and 5 (near the end of the inlet pipe 1). It then mixes in the perforated areas on the surfaces of the inner and outer guide plates 4 and 5, and finally remixes at the rear end of the inner and outer guide plates 4 and 5 (near the end of the tube sheet 3). This effectively reduces the direct impact of the inlet flow on the tube sheet 3 and the tube bundle, and improves the flow distribution characteristics between the tube bundles on the tube side. Numerical simulations have verified that the graded perforated flow guide head structure for shell-and-tube heat exchangers can improve the flow uniformity between the tube bundles on the tube side by 10-30%, which is a significant effect and highly feasible.

[0050] Based on the concept of changing the flow state in the head region, this invention discloses a graded perforated flow diversion head structure for shell-and-tube heat exchangers. This head structure has the advantages of simple structure, low resistance, easy installation, low cost, high feasibility, and wide application range, thereby improving the flow distribution in the head region of shell-and-tube heat exchangers. This head structure can achieve three-dimensional flow distribution of the inlet flow in the head region, thereby greatly improving the flow distribution in the head region.

[0051] The above describes the preferred embodiments of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A graded perforated flow guide head structure for a shell and tube heat exchanger, characterized by: It includes an inlet pipe (1), a head cover (2), a flow guide assembly and a tube sheet (3); The head cover (2) is a hemispherical structure, which is coaxially connected to the tube sheet (3) and encloses a flow guide area; the inlet pipe (1) is installed on the side wall of the head cover (2) and is connected to the flow guide area; the central axis of the inlet pipe (1) is perpendicular to the plane of the tube sheet (3); The flow guide assembly comprises an inner flow guide assembly and an outer flow guide assembly arranged in the flow guide area near the inlet pipe (1); the inner flow guide assembly comprises two inner flow guide plates (4) symmetrically arranged in an octave shape and respectively mounted on the inner wall of the head cover (2), the symmetry planes of which are perpendicular to the tube sheet (3) and coincide with the mid-plane of the inlet pipe (1); the two ends of the two inner flow guide plates (4) are respectively spaced apart from the inlet pipe (1) and the tube sheet (3); the distance between one end of the two inner flow guide plates (4) near the inlet pipe (1) is smaller than the distance between the other ends; The outer guide assembly comprises two outer guide plates (5) symmetrically arranged in an eight-shaped pattern on both sides of the symmetry plane and respectively mounted on the inner wall of the head cover (2), the two outer guide plates (5) being respectively located on the side of the two inner guide plates (4) away from the symmetry plane; a distance is left between the two ends of the two outer guide plates (5) and the inlet pipe (1) and the tube plate (3), and the distance between one end of the two outer guide plates (5) close to the inlet pipe (1) is smaller than the distance between the other ends; a plurality of guide holes are evenly distributed on the inner guide plate (4) and the outer guide plate (5), and the mapped lengths of the inner guide plate (4) and the outer guide plate (5) on the symmetry plane are equal and overlap; The vertical distance between the plane where the inner guide plate (4) and the outer guide plate (5) are located near one end of the inlet pipe (1) and the outlet end face of the inlet pipe (1) is recorded as d1; the mapped length of the inner guide plate (4) and the outer guide plate (5) on the symmetry plane is recorded as d2; the vertical distance between the plane where the inner guide plate (4) and the outer guide plate (5) are located near one end of the tube sheet (3) and the tube sheet (3) is recorded as d3; then d1, d2, and d3 satisfy d1:d2:d3 = 1:4:

5.

2. The graded perforated flow guide head structure for a shell and tube heat exchanger according to claim 1, characterized in that: The included angle α1 between each inner guide plate (4) and the symmetry plane is 20° to 40°.

3. The graded perforated flow guide head structure for a shell and tube heat exchanger according to claim 2, characterized in that: The included angle α2 between each of the outer guide plates (5) and the symmetry plane is 50° to 70°.

4. The graded perforated flow guide head structure for a shell and tube heat exchanger according to claim 3, characterized in that: The distance between the two inner guide plates (4) close to one end of the inlet pipe (1) is recorded as d4; The distance between adjacent inner guide plates (4) and outer guide plates (5) close to one end of the inlet pipe (1) is recorded as d5; d4 and d5 are sufficient to evenly divide the flow cross section of the inlet pipe (1) into 5 equal parts.

5. The graded perforated flow guide head structure for a shell and tube heat exchanger according to claim 4, characterized in that: The opening rate of the inner guide plate (4) and the outer guide plate (5) is 10% to 20%.

6. The graded perforated flow guide head structure for a shell and tube heat exchanger according to claim 5, characterized in that: The thickness of the inner guide plate (4) and the outer guide plate (5) are both 5 to 10 mm.

7. The graded perforated flow guide head structure for a shell and tube heat exchanger according to claim 6, characterized in that: The tube plate (3) comprises a mounting plate (6) and a plurality of heat exchange tubes (7) evenly distributed on the mounting plate (6) and connected to the guide area.

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