Discontinuous spiral baffle heat exchanger for compressed air cooling

Abstract

The present invention provides a discontinuous spiral baffle heat exchanger for compressed air cooling, which can solve the problems of leakage, low heat exchange efficiency in the central area, and high processing difficulty of existing spiral baffle heat exchangers. It includes a cylindrical outer shell, with tube sheets fixedly connected at both ends of the outer shell, and a tube box connected to the outer side of the tube sheet. The outer shell is axially provided with spiral baffles and a heat exchange tube bundle, and the heat exchange tube bundle passes through the spiral baffles and tube sheets and connects to the tube box. It also includes a cylindrical inner shell arranged coaxially with the outer shell, with the two tube sheets fixedly connected at both ends of the inner shell, and the diameter ratio of the outer shell to the inner shell is 2:1 to 5:1. The spiral baffle is fixedly installed between the outer shell and the inner shell, and is composed of at least four sector-shaped flat plates arranged in a spiral, and the edges of two adjacent sector-shaped flat plates overlap along the axial projection of the outer shell.

Description

Technical Field

[0001] The invention relates to the field of heat exchange equipment, in particular to a discontinuous spiral baffle heat exchanger for compressed air cooling. Background Art

[0002] According to the "China Compressed Air Drying and Purification Industry Production, Sales, Demand, and Transformation and Upgrading Analysis Report," compressed air is the second largest energy source after electricity, with applications spanning industries and sectors such as bio-fermentation, petroleum, chemical, food, and pharmaceuticals. However, because compressed air contains a large amount of water, it cannot be used directly. Therefore, it often needs to be cooled to remove the water before being heated and conditioned to a suitable level. This can be achieved using a heat exchanger.

[0003] Due to the obstruction of the baffles and other reasons, the traditional shell and tube heat exchanger has serious back-mixing of the shell-side fluid on the leeward side of the connection between the baffle and the shell. Part of the fluid cannot fully participate in heat transfer, which reduces the heat transfer efficiency. Therefore, spiral baffle heat exchangers are often used in industry to replace shell and tube heat exchangers to cool compressed air. Spiral baffle heat exchangers are generally composed of shell, tube sheet, heat exchange tubes, spiral baffles and tube box. The ideal spiral baffle should have a continuous spiral surface, but due to the difficulty of processing, the baffles currently used are generally composed of several 1 / 4 fan-shaped flat plates instead of curved surfaces, which are connected alternately to form an approximate spiral surface. Such baffles are called discontinuous spiral baffles. When a heat exchanger is operating, the shell-side fluid flows within the spiral channel formed by the spiral baffles. The fluid in this spiral channel is driven by centrifugal force, resulting in a low velocity zone in the center. For discontinuous spiral baffles, there is often a gap between the overlaps of two adjacent baffles. This gap can cause leakage due to the low velocity of the fluid flowing through this gap. The closer to the center of the heat exchanger's shell, the larger the gap, the lower the fluid velocity, and the more severe the leakage. Leakage can affect heat transfer between the tube-side and shell-side media in the heat exchanger, reducing heat exchange efficiency.

[0004] Patent No. ZL20141082979.2 discloses a spiral baffle heat exchanger. The heat exchanger's shell features a seamless spiral channel formed by connecting at least two baffles, with partitions connecting adjacent baffles. This heat exchanger prevents leakage of fluid in the shell, ensuring its heat transfer performance. However, this method of using partitions to prevent leakage increases assembly complexity and does not address the fundamental issue of low heat transfer efficiency in the center of the heat exchanger.

[0005] Patent No. ZL20161084491.5 discloses a spiral baffle for a heat exchanger. The baffle is equipped with several fins along the spiral surface of the spiral annular baffle. These fins ensure a consistent flow rate throughout the heat exchanger shell, preventing leakage from the gap between the baffle and the central cylindrical core tube or shell. However, this method of adding fins increases flow resistance, and the continuous production process for spiral baffles is complex, making it unsuitable for large-scale production.

[0006] Patents ZL 20181162351.8 and ZL 20141012688.5 disclose a heat exchanger with spiral baffles and a core tube. The core tube is semi-cylindrical, with spiral baffles positioned on its arcuate surface. The two core tubes are connected by threads or mortise and tenon joints. This type of spiral baffle with a core tube is more difficult to manufacture than a discontinuous spiral baffle. While it can slightly reduce fluid leakage in the center area, it is not suitable for high-flow compressed air heat exchange. Summary of the Invention

[0007] In response to the technical problems of leakage in existing spiral baffle heat exchangers, low heat exchange efficiency in the central area, and great processing difficulty, the present invention provides a discontinuous spiral baffle heat exchanger for compressed air cooling, which can avoid leakage of shell-side fluid during flow, effectively reduce the area with low heat exchange efficiency in the center, improve the heat exchange efficiency of the heat exchanger, and at the same time is simple to process and easy to assemble.

[0008] The technical solution is as follows: a discontinuous spiral baffle heat exchanger for compressed air cooling, which includes a cylindrical outer shell, with tube sheets fixedly connected at both ends of the outer shell, a tube box connected to the outside of the tube sheet, and spiral baffles and heat exchange tube bundles are axially arranged in the outer shell, and the heat exchange tube bundle is connected to the tube box through the spiral baffles and the tube sheet; it is characterized in that: it also includes a cylindrical inner shell coaxially arranged with the outer shell, the two ends of the inner shell are respectively fixed to the two tube sheets, and the diameter ratio of the outer shell to the inner shell is 2:1~5:1; the spiral baffle is fixedly installed between the outer shell and the inner shell, and the spiral baffle is composed of at least four fan-shaped flat plates arranged in a spiral, and the edges of two adjacent fan-shaped flat plates coincide along the axial projection of the outer shell.

[0009] It is further characterized by:

[0010] The sector-shaped flat plates are arranged in a spiral manner at a spiral angle of 20° to 30°.

[0011] The sector angle of the axial projection of the sector-shaped flat plate is 95° to 100°.

[0012] The axial projections of the sector-shaped flat plates are evenly distributed along the circumference of the inner shell, and the angle between the center lines of the axial projections of two adjacent sector-shaped flat plates is 90°.

[0013] A gap of less than 2 mm is left between the inner arc of the sector-shaped flat plate and the inner shell, and between the outer arc and the outer shell.

[0014] The spiral baffle is fixedly installed between the outer shell and the inner shell by a tie rod. The tie rod is arranged along the axial direction of the outer shell. One end of the tie rod is fixedly connected to one of the tube plates, and the other end passes through the fan-shaped flat plate and is locked to the fan-shaped flat plate at the end by a nut. A distance tube is mounted on the tie rod between two adjacent fan-shaped flat plates.

[0015] Two pull rods are passed through each of the sector-shaped flat plates.

[0016] The upper side wall of the outer shell is provided with a compressed air inlet, the end side wall is provided with a compressed air outlet, the pipe box at the end of the outer shell is provided with a medium inlet, and the other pipe box is provided with a medium outlet.

[0017] A plurality of pressure balancing holes are opened on the end side wall of the inner shell.

[0018] The beneficial effects of the present invention are:

[0019] The discontinuous spiral baffle heat exchanger for compressed air cooling of the present invention has an inner shell coaxial with the outer shell arranged in an outer shell, and the diameter ratio of the inner shell and the outer shell is 2:1~5:1, thereby effectively reducing the area with low heat exchange efficiency in the center of the outer shell, improving the heat exchange efficiency, and reducing the flow pressure loss. At the same time, the spiral baffle adopts a discontinuous design, and the edges of the adjacent two fan-shaped flat plates along the axial projection of the outer shell coincide, so that there is no gap between the two adjacent fan-shaped flat plates, avoiding the occurrence of leakage of the shell-side fluid during the flow process, and ensuring the heat exchange performance of the heat exchanger; the spiral baffle with a discontinuous design is simple to process and has low assembly difficulty, and can realize the formation of spiral airflow of compressed air in the shell, reducing flow resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the front view of the present invention;

[0021] Figure 2 for Figure 1 Enlarged view of area A in the middle;

[0022] Figure 3 It is an axial projection view of the inner shell, outer shell and spiral baffle.

[0023] Figure numerals: 1-outer shell; 2-inner shell; 3-tube sheet; 4-tube box; 5-heat exchange tube bundle; 6-fan-shaped flat plate; 7-pull rod; 8-pull rod hole; 9-nut; 10-spacer tube; 11-heat exchange tube hole; 12-compressed air inlet; 13-compressed air outlet; 14-medium inlet; 15-medium outlet; 16-pressure balance hole. DETAILED DESCRIPTION

[0024] See Figures 1 to 3 The present invention relates to a discontinuous spiral baffle heat exchanger for compressed air cooling, which comprises an outer shell 1 and an inner shell 2 coaxially arranged and both cylindrical. Tube sheets 3 are welded and fixed at both ends of the outer shell 1 and the inner shell 2. The outer side of the tube sheet 3 is connected to a tube box 4. Spiral baffles and heat exchange tube bundles 5 are axially arranged in the outer shell 1. The heat exchange tube bundles 5 pass through the spiral baffles and the tube sheet 3 and are connected to the tube box 4. The diameter ratio D1:D2 of the outer shell 1 and the inner shell 2 is 2:1~5:1. The spiral baffle is fixedly installed between the outer shell 1 and the inner shell 2. The spiral baffle is composed of at least four sector-shaped flat plates 6 arranged in a spiral with a spiral angle of 20°~30°, and adjacent The two fan-shaped flat plates 6 overlap along the axial projection edges of the outer shell 1; the fan angle α of the axial projection of the fan-shaped flat plate 6 is 95°~100°, the axial projection of the fan-shaped flat plate 6 is evenly distributed along the circumference of the inner shell 2, and the angle β between the center lines of the axial projections of two adjacent fan-shaped flat plates 6 is 90°. Such a design has a reasonable structure, which can ensure that the axial projection edges of the two adjacent fan-shaped flat plates overlap along the outer shell without making the overlapping area too large; a gap d of less than 2 mm is left between the inner arc of the fan-shaped flat plate 6 and the inner shell 2, and between the outer arc and the outer shell 1, which can effectively ensure that the compressed air forms a spiral airflow in the shell, ensuring a good heat exchange effect.

[0025] See Figures 1 to 3 The spiral baffle is fixedly installed between the outer shell 1 and the inner shell 2 by a tie rod 7. The tie rod 7 is arranged along the axial direction of the outer shell 1. One end of the tie rod 7 is fixedly connected to one of the tube sheets 3 by a thread, and the other end passes through the tie rod hole 8 on the sector plate 6 and is locked to the sector plate 6 at the end by a nut 9. A distance tube 10 is installed on the tie rod 7 between two adjacent sector plates 6. The diameter of the distance tube 10 is larger than the tie rod hole 8. In order to ensure that the spiral baffle is fixed stably and reliably, two tie rods 7 are passed through each sector plate 6. Figure 3 In the middle is a heat exchange tube hole 11 for the heat exchange tube to pass through.

[0026] See Figure 1The outer shell 1 has a compressed air inlet 12 on its upper sidewall and a compressed air outlet 13 on its lower sidewall. A medium inlet 14 is provided on a pipe box 4 at the end of the outer shell 1, and a medium outlet 15 is provided on another pipe box 4. During operation, compressed air flows between the outer shell and the inner shell, and a heat exchange medium flows into the heat exchange tube bundle, exchanging heat with the compressed air in the shell side to achieve heat exchange.

[0027] See Figure 1 There are several pressure balance holes 16 on the end side wall of the inner shell 2. With this design, even if the wall thickness of the inner shell is thin, it will not be deformed by the pressure in the shell side, reducing the manufacturing cost without affecting the heat exchange efficiency and flow loss.

Claims

1. A discontinuous spiral baffle heat exchanger for compressed air cooling, comprising a cylindrical outer shell, tube sheets fixedly connected at both ends of the outer shell, a tube box connected to the outer side of the tube sheet, spiral baffles and a heat exchange tube bundle axially disposed within the outer shell, the heat exchange tube bundle passing through the spiral baffles and the tube sheet and communicating with the tube box; characterized in that: It also includes a cylindrical inner shell coaxially arranged with the outer shell, with both ends of the inner shell respectively fixed to the two tube sheets, and the diameter ratio of the outer shell to the inner shell is 2:1 to 5:1; the spiral baffle is fixedly installed between the outer shell and the inner shell, and the spiral baffle is composed of at least four sector-shaped flat plates arranged in a spiral. The spiral baffle adopts a discontinuous design, and the axial projection edges of two adjacent sector-shaped flat plates along the outer shell coincide, so that there is no gap between the two adjacent sector-shaped flat plates; The sector angle of the axial projection of the sector-shaped flat plate is 95° to 100°; The axial projections of the sector-shaped flat plates are evenly distributed along the circumference of the inner shell, and the angle between the center lines of the axial projections of two adjacent sector-shaped flat plates is 90°; The sector-shaped flat plates are spirally arranged at a helical angle of 20° to 30°; A gap of less than 2 mm is left between the inner arc of the sector-shaped flat plate and the inner shell, and between the outer arc and the outer shell.

2. The discontinuous spiral baffle heat exchanger for compressed air cooling according to claim 1, characterized in that: The spiral baffle is fixedly installed between the outer shell and the inner shell by a tie rod. The tie rod is arranged along the axial direction of the outer shell. One end of the tie rod is fixedly connected to one of the tube plates, and the other end passes through the fan-shaped flat plate and is locked to the fan-shaped flat plate at the end by a nut. A distance tube is mounted on the tie rod between two adjacent fan-shaped flat plates.

3. The discontinuous spiral baffle heat exchanger for compressed air cooling according to claim 2, characterized in that: Two pull rods are passed through each of the sector-shaped flat plates.

4. The discontinuous spiral baffle heat exchanger for compressed air cooling according to claim 1, characterized in that: The upper side wall of the outer shell is provided with a compressed air inlet, the end side wall is provided with a compressed air outlet, the pipe box at the end of the outer shell is provided with a medium inlet, and the other pipe box is provided with a medium outlet.

5. The discontinuous spiral baffle heat exchanger for compressed air cooling according to claim 1, characterized in that: A plurality of pressure balancing holes are opened on the end side wall of the inner shell.

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