A double-pipe spiral coil heat exchanger

Abstract

The application discloses a double-pipe spiral coil heat exchanger and particularly relates to the technical field of heat exchange equipment, which comprises a shell pipe body and an inner spiral pipe. The shell pipe body comprises an outer sleeve pipe, threaded connection holes, water inlet pipes, water outlet pipes, a flange body and end connecting plates. The side walls of the outer sleeve pipe are respectively fixedly connected with the water inlet pipes and the water outlet pipes. The end portions of the water inlet pipes and the water outlet pipes are fixedly connected with the flange body. The threaded connection holes are formed in the flange body. The end connecting plates are fixedly connected to the two ends of the outer sleeve pipe. The inner spiral pipe is arranged in the outer sleeve pipe. The outer sleeve pipe and the inner spiral pipe form a double-pipe spiral coil structure, which significantly increases the heat exchange area in a limited space. Meanwhile, the fluid flow direction of the inner spiral pipe is reversely arranged with the fluid flow direction in the annular cavity of the outer sleeve pipe, thereby improving the heat exchange temperature difference utilization rate and the heat exchange efficiency. In addition, the spiral coil structure enables the fluid to be subjected to centrifugal force when flowing, thereby effectively destroying the fluid boundary layer and reducing the thermal resistance layer.

Description

Technical Field

[0001] This invention relates to the field of heat exchange equipment technology, and more specifically, to a shell-and-tube spiral coil heat exchanger. Background Technology

[0002] A shell-and-tube heat exchanger is a common type of indirect heat exchange equipment. Its basic structure consists of two tubes of different diameters nested together. The two fluids flow in the inner tube and the annular channel, respectively, and exchange heat through the tube walls. Due to its simple structure and strong pressure resistance, the shell-and-tube heat exchanger is widely used in heat pumps, refrigeration, chemical waste heat recovery and other fields. Traditional spiral coil heat exchangers suffer from several challenges. First, under high temperature difference conditions, the asynchronous thermal expansion of the inner and outer coils leads to stress concentration. Second, scaling buildup on the inner wall of the spiral coil after long-term operation. Third, mismatched flow rates between the two fluids result in reduced heat exchange efficiency. Furthermore, when the heat exchanger operates under large temperature differences, the asynchronous thermal expansion of the outer and inner spiral coils due to material differences or temperature variations can cause stress concentration or seal failure at pipe joints. Additionally, scaling easily forms on the inner wall of the spiral coil after long-term operation, reducing heat exchange efficiency, and existing heat exchangers lack effective anti-scaling measures. Finally, when the flow rate ratio of the two fluids deviates from the design value, the heat exchange efficiency drops significantly, and existing devices lack flow matching and adjustment functions.

[0003] Therefore, a shell-and-tube spiral coil heat exchanger is proposed to address the above problems. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a shell-and-tube spiral coil heat exchanger to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a shell-and-tube spiral coil heat exchanger, comprising an outer shell tube and an inner spiral tube. The outer shell tube includes an outer sleeve, threaded connection holes, an inlet pipe, an outlet pipe, a flange body, and end connecting pieces. The inlet pipe and the outlet pipe are respectively fixedly connected to the side wall of the outer sleeve. The flange body is fixedly connected to the ends of the inlet pipe and the outlet pipe. The flange body has threaded connection holes. The two ends of the outer sleeve are fixedly connected to end connecting pieces. The inner spiral tube passes through the inside of the outer sleeve. The annular cavity between the outer tube and the inner spiral tube is connected to form an outer fluid channel. In use, the first heat exchange medium enters the annular cavity between the outer tube and the inner spiral tube through the inlet pipe, flows along the cavity, and is discharged from the outlet pipe. The fluid flow direction of the inner spiral tube is set in the opposite direction to the fluid flow direction in the annular cavity of the outer tube, forming a pure counter-current heat exchange structure, which makes full use of the logarithmic mean temperature difference to improve the heat exchange capacity.

[0006] Preferably, the inner spiral tube includes a spiral tube body, an output port, and an input port. The spiral tube body spirally passes through the inside of the outer casing tube. Both ends of the spiral tube body extend out of the outer casing tube, and the output port and input port are fixedly connected to both ends of the spiral tube body, respectively. The second heat exchange medium enters the interior of the inner spiral tube through the input port, flows along the spiral base tube, and is finally discharged from the output port.

[0007] Preferably, the spiral tube body includes a spiral base tube and a heat insulation strip. The spiral tube body is formed by winding the spiral base tube, and the gaps between adjacent spiral base tubes are filled with heat insulation strips. The heat insulation strips between adjacent spiral base tubes can block ineffective heat conduction between the high and low temperature tubes, prevent thermal short circuits, and reduce heat loss. Heat is exchanged between the two media through the inner spiral tube wall, realizing continuous heat exchange operation.

[0008] Preferably, the spiral base tube is a cylindrical spiral coil structure, the spiral diameter of the spiral base tube is 60%-80% of the inner diameter of the outer sleeve, and the pitch of the spiral base tube is 1.5-3 times the outer diameter of the spiral base tube. When the fluid flows in the spiral tube body, centrifugal force will be generated, which will effectively destroy the stable boundary layer on the fluid surface, increase the turbulence intensity, and enhance the heat transfer between the tube walls.

[0009] Preferably, the heat insulation strip is one of scandium oxide fiber blanket, aerogel silicate heat insulation board or ceramic fiber heat insulation strip, with a temperature resistance ≥400℃ and a thermal conductivity ≤0.15W / (m·K). It is used to block the heat transfer between two adjacent spiral base tubes, avoid thermal short circuit, and ensure that heat is transferred between the two fluids through the tube wall as much as possible, rather than between adjacent tube coils of the spiral tube itself.

[0010] Preferably, the inner spiral tube is an integral seamless tube structure made of stainless steel with a wall thickness of 0.8-2.5mm and a maximum pressure of ≥16MPa, suitable for high-pressure fluid heat exchange conditions.

[0011] Preferably, the fluid flow direction of the inner spiral tube is opposite to the fluid flow direction in the annular cavity of the outer tube, forming a pure counter-current heat exchange structure.

[0012] Preferably, a corrugated compensator is provided between the end connecting piece and the inner spiral tube to absorb the difference in axial thermal expansion between the outer tube and the inner spiral tube caused by the temperature difference, and a flexible graphite packing seal is provided at the mating point between the end connecting piece and the inner spiral tube.

[0013] Preferably, a positioning support block is provided between the outer tube and the inner spiral tube. The positioning support block is made of high-temperature resistant metal or ceramic material and is distributed at intervals along the axial direction of the spiral tube to ensure that the inner spiral tube is always located at the center of the outer tube.

[0014] Preferably, the inner wall of the inner spiral tube is coated with a hydrophobic anti-scaling coating. The coating is a polytetrafluoroethylene coating or a vitrified coating, and the coating thickness is 0.05-0.3 mm, which is used to reduce scale adhesion on the inner wall of the inner spiral tube.

[0015] The technical effects and advantages of this invention are as follows: Compared with existing technologies, this coaxial spiral coil heat exchanger forms a coaxial spiral coil structure through an outer tube and an inner spiral tube, which significantly increases the heat exchange area within a limited space. At the same time, the fluid flow direction of the inner spiral tube is set in the opposite direction to the fluid flow direction in the annular cavity of the outer tube, forming a pure counter-current heat exchange structure, which improves the utilization rate of heat exchange temperature difference and improves heat exchange efficiency. Furthermore, the spiral coil structure subjectes the fluid to centrifugal force during flow, which can effectively break the fluid boundary layer, thin the thermal resistance layer, enhance the heat transfer effect, increase turbulence intensity, and further improve heat transfer efficiency. Attached Figure Description

[0016] Figure 1 This is a cross-sectional three-dimensional structural diagram of the outer sleeve of the present invention.

[0017] Figure 2 This is a first-view three-dimensional structural diagram of the outer casing tube of the present invention.

[0018] Figure 3 This is a three-dimensional structural diagram of the spiral base tube and heat insulation strip of the present invention.

[0019] Figure 4 This is a two-dimensional structural diagram of the outer casing tube of the present invention from a second perspective.

[0020] The attached figures are labeled as follows: 1. Outer shell tube; 101. Outer sleeve; 102. Threaded connection hole; 103. Inlet pipe; 104. Outlet pipe; 105. Flange body; 106. End connecting piece; 2. Inner spiral tube; 201. Spiral tube body; 2011. Spiral base tube; 2012. Insulation strip; 202. Output port; 203. Input port. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 As attached Figures 1 to 4The illustrated spiral coil heat exchanger includes an outer shell tube 1 and an inner spiral tube 2. The outer shell tube 1 includes an outer sleeve 101, a threaded connection hole 102, an inlet pipe 103, an outlet pipe 104, a flange body 105, and an end connecting piece 106. The inlet pipe 103 and the outlet pipe 104 are fixedly connected to the side wall of the outer sleeve 101, respectively. The flange body 105 is fixedly connected to the ends of the inlet pipe 103 and the outlet pipe 104. The flange body 105 has a threaded connection hole 102. The end connecting pieces 106 are fixedly connected to both ends of the outer sleeve 101. The inner spiral tube 2 passes through the inside of the outer sleeve 101.

[0023] The annular cavity between the outer tube 101 and the inner spiral tube 2 is connected to form an outer fluid channel. In use, the first heat exchange medium enters the annular cavity between the outer tube 101 and the inner spiral tube 2 through the inlet pipe 103, flows along the cavity, and is discharged from the outlet pipe 104. The fluid flow direction of the inner spiral tube 2 is set in the opposite direction to the fluid flow direction in the annular cavity of the outer tube 101, forming a pure counter-current heat exchange structure, which makes full use of the logarithmic mean temperature difference to improve the heat exchange capacity. The inner wall of the inner spiral tube 2 is coated with a hydrophobic anti-scaling coating. The coating is a polytetrafluoroethylene coating or a vitrified coating with a thickness of 0.05-0.3 mm, which is used to reduce the scale adhesion on the inner wall of the inner spiral tube 2.

[0024] Example 2 Based on Example 1, the solution in Example 1 will be further described in detail below, with reference to the specific working method described in detail: Reference Figure 1 In a preferred embodiment, the inner spiral tube 2 includes a spiral tube body 201, an output port 202, and an input port 203. The spiral tube body 201 spirally passes through the inside of the outer casing 101, and both ends of the spiral tube body 201 extend out of the outer casing 1. The output port 202 and the input port 203 are fixedly connected to both ends of the spiral tube body 201. The inner spiral tube 2 is an integral seamless tube structure made of stainless steel with a wall thickness of 0.8-2.5mm and a maximum pressure of ≥16MPa. It is suitable for high-pressure fluid heat exchange conditions, which improves the reliability and service life of the equipment. The second heat exchange medium enters the interior of the inner spiral tube 2 through the input port 203, flows along the spiral base tube 2011, and is finally discharged from the output port 202.

[0025] Reference Figure 1 , Figure 3In a preferred embodiment, the spiral tube body 201 includes a spiral base tube 2011 and a heat insulation strip 2012. The spiral tube body 201 is formed by winding the spiral base tube 2011. The gaps between adjacent spiral base tubes 2011 are filled with heat insulation strips 2012. The heat insulation strips 2012 between adjacent spiral base tubes 2011 can block ineffective heat conduction between high and low temperature tubes, prevent thermal short circuits, and reduce heat loss. Heat is exchanged between the two media through the inner spiral tube 2 wall, realizing continuous heat exchange operation. The spiral base tube 2011 is a cylindrical spiral coil structure. The spiral diameter of the spiral base tube 2011 is 60%-80% of the inner diameter of the outer tube 101, and the pitch of the spiral base tube 2011 is 1.5-3 times the outer diameter of the spiral base tube 2011. When the fluid flows in the spiral tube body 201, centrifugal force is generated, which effectively destroys the stable boundary layer on the fluid surface, increases the turbulence intensity, and enhances the heat transfer between the tube walls.

[0026] Reference Figure 3 As a preferred embodiment, the thermal insulation strip 2012 is made of one of scandium oxide fiber blanket, aerogel silicate thermal insulation board or ceramic fiber thermal insulation strip, with a temperature resistance ≥400℃ and a thermal conductivity ≤0.15W / (m·K). It is used to block the heat transfer between two adjacent spiral base tubes 2011, avoid thermal short circuit, and ensure that heat is transferred between the two fluids through the tube wall as much as possible, rather than between adjacent tube coils of the spiral tube itself.

[0027] Reference Figure 1 In a preferred embodiment, the fluid flow direction of the inner spiral tube 2 is reversed with the fluid flow direction in the annular cavity of the outer tube 101, forming a pure counter-current heat exchange structure.

[0028] A corrugated compensator is provided between the end connecting piece 106 and the inner spiral tube 2 to absorb the difference in axial thermal expansion between the outer tube 101 and the inner spiral tube 2 caused by temperature difference. A flexible graphite packing seal is provided at the mating point between the end connecting piece 106 and the inner spiral tube 2. A positioning support block is provided between the outer tube 101 and the inner spiral tube 2. The positioning support block is made of high-temperature resistant metal or ceramic material and is distributed at intervals along the axial direction of the spiral tube to ensure that the inner spiral tube 2 is always located in the center position of the outer tube 101.

[0029] The working process of the present invention is as follows: First, the first heat exchange medium enters the annular cavity between the outer sleeve 101 and the inner spiral tube 2 through the inlet pipe 103, flows along the cavity and is discharged from the outlet pipe 104; the second heat exchange medium enters the interior of the inner spiral tube 2 through the inlet pipe 203, flows along the spiral base tube 2011 and is finally discharged from the outlet pipe 202. During the heat exchange process, the fluid flow direction of the inner spiral tube 2 is set in the opposite direction to the fluid flow direction in the annular cavity of the outer tube 101, forming a pure counter-current heat exchange structure, which makes full use of the logarithmic mean temperature difference to improve the heat exchange capacity. Meanwhile, the cylindrical spiral coil structure of the spiral base tube 2011 causes the fluid to be subjected to centrifugal force during flow, which destroys the fluid boundary layer at the tube wall, thins the thermal resistance layer, enhances the turbulence intensity, and thus strengthens the heat transfer effect. Furthermore, the heat insulation strip 2012 filling the gap between adjacent spiral base tubes 2011 is made of high-temperature resistant heat insulation material, which effectively blocks the heat transfer between adjacent spiral base tubes 2011, avoids thermal short circuit, and ensures that heat is transferred between the two fluids through the tube wall as much as possible, rather than between adjacent tube coils of the spiral tube itself. The above is the working principle of this type of shell-and-tube spiral coil heat exchanger.

Claims

1. A shell-and-tube spiral coil heat exchanger, comprising an outer shell tube (1) and an inner spiral tube (2), characterized in that: The outer casing (1) includes an outer sleeve (101), a threaded connection hole (102), an inlet pipe (103), an outlet pipe (104), a flange body (105), and an end connecting piece (106). The inlet pipe (103) and the outlet pipe (104) are fixedly connected to the side wall of the outer sleeve (101). The flange body (105) is fixedly connected to the end of the inlet pipe (103) and the outlet pipe (104). The flange body (105) has a threaded connection hole (102) on it. The end connecting pieces (106) are fixedly connected to both ends of the outer sleeve (101). An inner spiral tube (2) is inserted inside the outer sleeve (101).

2. The coaxial spiral coil heat exchanger according to claim 1, characterized in that: The inner spiral tube (2) includes a spiral tube body (201), an output port (202), and an input port (203). The spiral tube body (201) spirally passes through the inside of the outer tube (101). Both ends of the spiral tube body (201) extend out of the outer tube body (1), and the output port (202) and the input port (203) are fixedly connected to both ends of the spiral tube body (201).

3. A shell-and-tube spiral coil heat exchanger according to claim 2, characterized in that: The spiral tube body (201) includes a spiral base tube (2011) and a heat insulation strip (2012). The spiral tube body (201) is formed by coiling the spiral base tube (2011), and the gaps between adjacent spiral base tubes (2011) are filled with heat insulation strips (2012).

4. A shell-and-tube spiral coil heat exchanger according to claim 3, characterized in that: The spiral base tube (2011) is a cylindrical spiral coil structure. The spiral diameter of the spiral base tube (2011) is 60%-80% of the inner diameter of the outer sleeve (101), and the pitch of the spiral base tube (2011) is 1.5-3 times the outer diameter of the spiral base tube (2011).

5. A coaxial spiral coil heat exchanger according to claim 3, characterized in that: The heat insulation strip (2012) is made of one of scandium oxide fiber blanket, aerogel silicate heat insulation board or ceramic fiber heat insulation strip, with a temperature resistance of ≥400℃ and a thermal conductivity of ≤0.15W / (m·K), and is used to block heat transfer between two adjacent spiral base tubes (2011).

6. A shell-and-tube spiral coil heat exchanger according to claim 1, characterized in that: The inner spiral tube (2) is an integral seamless tube structure made of stainless steel with a wall thickness of 0.8-2.5mm and a maximum pressure of ≥16MPa.

7. A shell-and-tube spiral coil heat exchanger according to claim 1, characterized in that: The fluid flow direction of the inner spiral tube (2) is reversed with the fluid flow direction in the annular cavity of the outer tube (101), forming a pure counter-current heat exchange structure.

8. A shell-and-tube spiral coil heat exchanger according to claim 1, characterized in that: A corrugated compensator is provided between the end connecting piece (106) and the inner spiral tube (2), and a flexible graphite packing seal is provided at the mating point between the end connecting piece (106) and the inner spiral tube (2).

9. A shell-and-tube spiral coil heat exchanger according to claim 1, characterized in that: A positioning support block is provided between the outer tube (101) and the inner spiral tube (2). The positioning support block is made of high-temperature resistant metal or ceramic material and is distributed at intervals along the axial direction of the spiral tube.

10. A shell-and-tube spiral coil heat exchanger according to claim 1, characterized in that: The inner wall of the inner spiral tube (2) is coated with a hydrophobic anti-scaling coating. The coating is a polytetrafluoroethylene coating or a vitrified coating, and the coating thickness is 0.05-0.3 mm.

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