Spiral double-pipe heat exchanger

Abstract

The invention provides a spiral double-pipe heat exchanger and relates to the technical field of heat exchangers, the spiral double-pipe heat exchanger comprises an outer pipe, an inner pipe, a positioning pipe, arc-shaped side plates and a heat preservation assembly, the inner pipe is located in the outer pipe, the inner pipe and the outer pipe form a double-pipe heat exchanger structure, one end of the positioning pipe penetrates through the outer pipe and is fixedly welded to the outer wall of the inner pipe, and the positioning pipe is fixedly welded to the outer pipe. By adopting the spiral inner pipe and the spiral outer pipe, when the metal temperature difference of the inner coil pipe and the outer coil pipe is large, the inner coil pipe and the outer coil pipe generate deformation of different sizes, and due to the fact that a large gap exists between the inner coil pipe and the outer coil pipe, the deformation is not mutually restricted; and the spiral coil pipe has larger elasticity relative to the straight pipe, so that most temperature difference stress can be eliminated, the use of an expansion joint can be avoided, and the cost and leakage risk can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of heat exchangers, in particular to a spiral tube-type heat exchanger. Background Art

[0002] A heat exchanger is a device that transfers heat from one fluid to another without allowing the fluids to mix with each other. There are many types of heat exchangers, such as shell and tube heat exchangers, plate heat exchangers, spiral plate heat exchangers, plate and shell heat exchangers, etc. Shell and tube heat exchangers are widely used because of their simple structure, ability to withstand greater pressure when working, and low resistance (pressure drop) to the heat exchange fluid.

[0003] The main structure of the shell and tube heat exchanger is that the outer tube is sleeved on the inner tube, and the two ends of the outer tube are welded to the inner tube through tube caps or cone shells, thus forming a group of shells; multiple groups of shells are connected in series through U-shaped elbows to connect the inner tubes in series, and the outer tubes are connected in series through the pipe mouths. One fluid flows in the inner tube, and the other fluid flows in the gap between the inner and outer tubes. The two cold and hot fluids exchange heat through the inner tube wall.

[0004] The inventors have found that conventional shell and tube heat exchangers have the following disadvantages during long-term use of shell and tube heat exchangers:

[0005] 1. Since the inner tube and the outer tube are relatively long straight tubes, when the metal temperature difference between the inner and outer tubes is large, or the metal expansion is different due to the different materials of the inner and outer tubes, a large temperature difference stress will be generated in the inner and outer tubes; in order to reduce the temperature difference stress, an expansion joint is added to the outer tube; the setting of the expansion joint increases the cost and adds more welding joints, thereby increasing the risk of leakage.

[0006] 2. In actual use, the effective heat exchange area is only the part of the inner tube covered by the outer tube. The part of the inner tube extending out of the outer tube and the U-shaped elbow part cannot play a role in heat transfer. In addition, the medium flow forms a dead zone in the part between the connecting pipe mouth between the outer tube and the inner and outer tube connectors, and the heat transfer effect is poor.

[0007] 3. The inner and outer pipes must be connected by welding with pipe caps or cone shells. Each set of casings must be connected in series with U-shaped elbows, pipe openings and flanges. There are many components and connecting joints, which increases the material and processing costs as well as the risk of leakage.

[0008] In order to solve the above technical problems, the present invention provides a spiral shell and tube heat exchanger. Summary of the invention

[0009] In view of the deficiencies in the prior art, the present invention provides a spiral shell and tube heat exchanger, which solves the problem that in the prior shell and tube heat exchanger, since the inner tube and the outer tube are relatively long straight tubes, when the metal temperature difference between the inner and outer tubes is large, a large temperature difference stress will be generated in the inner and outer tubes, and an expansion joint needs to be added to the outer tube. In addition, there are many components and connecting joints for connection, which increases the cost and the risk of leakage. In addition, a dead zone is formed in the medium flow in the part between the connecting pipe mouth between the outer tube and the inner and outer tube connecting pieces, resulting in a poor heat transfer effect.

[0010] To achieve the above objectives, the present invention is implemented through the following technical solutions: A spiral shell and tube heat exchanger, comprising:

[0011] An outer tube and an inner tube, wherein the inner tube is located inside the outer tube, and the inner tube and the outer tube form a shell-and-tube heat exchanger structure, and the outer tube and the inner tube are spiral coils with equal spiral radius and equal pitch;

[0012] A positioning tube, one end of which passes through the outer tube, and the positioning tube is fixed to the outer wall of the inner tube by welding, and the positioning tube is fixed to the outer tube by welding;

[0013] An arc-shaped side plate, wherein a positioning hole is opened on the side of the arc-shaped side plate, the positioning tube is fixedly inserted in the positioning hole, and a support seat is fixedly connected to the bottom of the arc-shaped side plate;

[0014] There are multiple positioning tubes, and the multiple positioning tubes are equidistantly distributed along the linear length direction of the outer tube and the inner tube;

[0015] The heat preservation component is an annular cylindrical structure of the shell and tube heat exchanger, and the heat preservation component is arranged on the inner side, the outer side and the end of the shell and tube heat exchanger structure.

[0016] Further preferably, the shell-and-tube heat exchanger structure has multiple groups, the spiral radius of the outer tube and the inner tube of the multiple groups of shell-and-tube heat exchanger structures decreases gradually, the multiple groups of shell-and-tube heat exchanger structures are arranged from the outside to the inside, the inner tubes of the multiple groups of shell-and-tube heat exchanger structures are linearly connected through the first outer tube disk connecting pipe, and the annular flow channels of the multiple groups of shell-and-tube heat exchanger structures are linearly connected through the second outer tube disk connecting pipe;

[0017] The whole formed by multiple sets of shell-and-tube heat exchangers has an A fluid inlet, an A fluid outlet, a B fluid inlet, and a B fluid outlet.

[0018] Further preferably, the thermal insulation structure comprises:

[0019] An inner cylinder located inside the shell-and-tube heat exchanger structure, wherein a heat-insulating cotton layer is fixedly arranged inside the inner cylinder;

[0020] The outer cylinder is located outside the shell-and-tube heat exchanger structure, the top end of the arc-shaped side plate is fixedly connected to a cross brace, the bottom end of the arc-shaped side plate is fixedly connected to a base, and the bottom ends of the outer cylinder and the inner cylinder are fixedly connected to the base;

[0021] The heat-insulating spiral fin plate is attached to the top of the shell-and-tube heat exchanger structure, and the outer side of the heat-insulating spiral fin plate is fixedly connected to the outer cylinder, and the inner side of the heat-insulating spiral fin plate is fixedly connected to the inner cylinder.

[0022] Further preferably, the base includes: an annular member, on which a widened portion is provided, the top of the widened portion of the annular member is fixedly connected to the bottom end of the arc-shaped side plate, and the bottom of the widened portion of the annular member is fixedly connected to a supporting foot.

[0023] Further preferably, the thermal insulation spiral sheet has a spiral angle of 380°-420°, and the thermal insulation spiral sheet is welded by a plurality of groups of short sheets with an angle less than 120°.

[0024] Further preferably, a through hole is opened on the side of the outer tube, the outer side of the positioning tube is welded to the edge of the through hole to form an outer welding portion, and the inner side of the positioning tube is welded to the inner tube to form an inner welding portion.

[0025] Further preferably, a blocking block is fixedly installed inside the positioning tube.

[0026] Further preferably, the diameter of the outer tube is 2-3 times the diameter of the inner tube, the diameter of the inner tube is 10-25CM, and the inner diameter of the positioning tube is not less than 5CM.

[0027] Further preferably, the first outer tube disk connecting pipe is U-shaped.

[0028] Further preferably, the shell-and-tube heat exchanger structure has multiple groups, the spiral radii of the outer tubes and the inner tubes of the multiple groups of shell-and-tube heat exchanger structures decrease gradually, and the multiple groups of the shell-and-tube heat exchanger structures are arranged from the outside to the inside;

[0029] Each group of the double-tube heat exchangers has an A fluid inlet, an A fluid outlet, a B fluid inlet, and a B fluid outlet.

[0030] The present invention provides a spiral tube heat exchanger having the following beneficial effects:

[0031] 1. The present invention adopts spiral inner and outer tubes (i.e., inner and outer coils). When the metal temperature difference between the inner and outer coils is large, the inner and outer coils will produce deformations of different sizes. Since there is a large gap between the inner and outer coils, their deformations will not be restricted by each other. The spiral coil has greater elasticity than the straight tube and can be used as a flexible element to produce elastic deformation in both horizontal and vertical directions, thereby eliminating most of the temperature difference stress and avoiding the use of expansion joints, thereby reducing the risk of cost and leakage.

[0032] 2. The present invention adopts spiral inner and outer tubes, and both inner and outer tubes can be coiled according to actual length requirements without being limited by the length of straight tubes. The length of a single spiral coil can be much longer than the length of a single straight tube, and the space occupied is small. The entire length of the spiral tube is an effective heat exchange area, which can greatly increase the heat exchange area per unit installation area.

[0033] 3. Compared with the traditional shell-and-tube heat exchanger, the spiral shell-and-tube heat exchanger of the present invention can greatly reduce the connecting elements and joints between the inner and outer tubes, between the inner tube sections, and between the outer tube sections, thereby reducing the material and processing costs and the risk of leakage.

[0034] 4. The present invention designs a positioning tube, one end of which passes through the outer tube and is welded and fixed to the outer wall of the inner tube. The positioning tube and the outer tube are also welded and fixed. The positioning tube can be used to ensure that the inner tube is basically located at the center of the outer tube. After processing the outer tube and inner tube in a longer spiral shape, the inner tube is spirally inserted into the outer tube, and then the positioning tube is welded, thereby ensuring the stability of the spiral shell-and-tube heat exchanger structure. When the fluid pressure in the inner tube changes, the inner tube will not shake and an unstable situation will not occur. In addition, the design of the positioning tube is convenient for overall support and installation of the arc-shaped side panels and the bottom support seat.

[0035] 5. The present invention can further extend the length of the heat exchange pipeline by connecting multiple sets of shell-and-tube heat exchanger structures in parallel or in series to meet the actual heat exchange requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a front view of a spiral shell and tube heat exchanger in the first embodiment of the present invention;

[0037] Figure 2 A cross-sectional view of a spiral tube heat exchanger in the first embodiment of the present invention;

[0038] Figure 3 for Figure 2 A partial enlarged view in the middle;

[0039] Figure 4 The structure of the positioning tube of a spiral tube-type heat exchanger in the first embodiment of the present invention;

[0040] Figure 5 A three-dimensional diagram of a spiral tube heat exchanger in the second embodiment of the present invention;

[0041] Figure 6 A cross-sectional view of a spiral tube heat exchanger in the second embodiment of the present invention;

[0042] Figure 7This is a schematic internal stereoscopic diagram from a first perspective of a spiral tube-type heat exchanger in Embodiment 2 proposed by the present invention;

[0043] Figure 8 It is a schematic internal stereoscopic diagram of a spiral shell-and-tube heat exchanger in the second embodiment of the present invention from a second viewing angle;

[0044] Fig. 9 It is a three-dimensional schematic diagram of a heat-insulating spiral fin plate of a spiral shell-and-tube heat exchanger in the second embodiment proposed by the present invention.

[0045] Among them, 1. curved side plate; 2. outer tube; 3. positioning tube; 4. support seat; 5. inner tube; 6. positioning hole; 7. outer welding part; 8. inner welding part; 9. block; 10. A fluid inlet; 11. B fluid outlet; 12. A fluid outlet; 13. B fluid inlet; 14. outer cylinder; 15. inner cylinder; 16. thermal insulation cotton layer; 17. cross brace; 18. base; 1801. annular part; 1802. widened part; 1803. support foot; 19. thermal insulation spiral plate; 20. first outer tube coil connecting pipe; 21. second outer tube coil connecting pipe. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Embodiment 1:

[0048] like Figure 1-Figure 3As shown, an embodiment of the present invention provides a spiral tube-type heat exchanger, which includes an outer tube 2, an inner tube 5, a positioning tube 3, an arc-shaped side plate 1, and a heat preservation component. The inner tube 5 is located inside the outer tube 2, and the inner tube 5 and the outer tube 2 form a tube-type heat exchanger structure. Specifically, the inner tube 5 is located inside the outer tube 2, and both ends of the inner tube 5 extend from both ends of the outer tube 2, and both ends of the outer tube 2 are contracted inwardly and fixedly connected to the inner tube 5, or the two ends of the outer tube 2 are fixedly connected to the outer wall of the inner tube 5 through a connecting joint. An annular flow channel is formed between the outside of the inner tube 5 and the inside of the outer tube 2, and the two ends of the inner tube 5 are respectively an A fluid inlet and an A fluid outlet, and the two ends of the annular flow channel are respectively a B fluid inlet and a B fluid outlet, and the B fluid inlet is close to the A fluid outlet. When in use, fluid A flows from the A fluid inlet to the A fluid outlet, and fluid B flows from the B fluid inlet and the B fluid outlet. Fluid A and fluid B flow in opposite directions, and fluid A and fluid B flow in opposite directions. Heat exchange is achieved through the outer wall of the inner tube 5; the outer tube 2 and the inner tube 5 are spiral coils with equal spiral radius and equal pitch, that is, the outer tube 2 is an outer coil, and the inner tube 5 is an inner coil. One end of the positioning tube 3 passes through the outer tube 2, and the positioning tube 3 is welded and fixed to the outer wall of the inner tube 5, and the positioning tube 3 is fixed to the outer tube 2. The outer tube 2 and the inner tube 5 are fixed by relying on the positioning tube 3 to ensure that the inner tube 5 is in the center position of the outer tube 2. A positioning hole 6 is opened on the side of the arc-shaped side plate 1, and the positioning tube 3 is fixedly inserted in the inside of the positioning hole 6. The bottom of the arc-shaped side plate 1 is fixedly connected with a support seat 4, and the support seat 4 is used to stably support the arc-shaped side plate 1. A plurality of positioning tubes 3 are provided, and the plurality of positioning tubes 3 are equidistantly distributed along the linear length direction of the outer tube 2 and the inner tube 5. The shell and tube heat exchanger structure is an annular cylindrical shape, and the insulation component is arranged on the inner side, outer side and end of the shell and tube heat exchanger structure. The insulation component is used to insulate the shell and tube heat exchanger structure.

[0049] The shell and tube heat exchanger used in the chemical industry generally adopts a multi-section straight tube structure, that is, the outer tube is sleeved on the inner tube, and the two ends of the outer tube are welded to the inner tube through a tube cap or a cone shell, thereby forming a set of shells; multiple sets of shells are connected in series through U-shaped elbows to connect the inner tubes in series, and the outer tubes are connected in series through the pipe mouth. One fluid flows in the inner tube, and the other fluid flows in the gap between the inner and outer tubes. The two cold and hot fluids exchange heat through the inner tube wall. Since the inner and outer tubes are relatively long straight tubes, when the metal temperature difference between the inner and outer tubes is large, or because the inner and outer tubes are made of different materials, the metal expansion When the temperature difference is different, a large temperature difference stress will be generated in the inner and outer pipes. The present invention adopts spiral inner and outer pipes (i.e., inner and outer coils). When the metal temperature difference of the inner and outer coils is large, the inner and outer coils will produce deformations of different sizes. Since there is a large gap between the inner and outer coils, their deformations will not be restricted by each other. The spiral coil has greater elasticity than the straight pipe and can be used as a flexible element to produce elastic deformation in both horizontal and vertical directions, thereby eliminating most of the temperature difference stress and avoiding the use of expansion joints, thereby reducing the risk of cost and leakage.

[0050] The use of spiral inner and outer tubes allows the inner and outer tubes to be made longer, and the spiral shell-and-tube heat exchanger has better integrity, especially the inner tube, which is basically a complete seamless pipe, greatly reducing the problem of liquid leakage in the inner tube.

[0051] like Figure 1 As shown in , an outer tube 2 and an inner tube 5 of suitable diameter are selected, and they are processed into spiral coils with the same spiral radius and pitch. Then, the outer coil with a larger diameter is spirally sleeved on the inner coil with a smaller diameter to form a group of spiral sleeves. The two ends of the outer tube 2 are squeezed and shrunk by a hydraulic mold, and the ends of the outer tube 2 are welded and fixed to the inner tube 5. Then, holes are opened on the outer side of the outer tube 2 near the two ends, and the inlet / outlet pipes are connected to form a B fluid inlet and a B fluid outlet. The two ends of the inner tube 5 are an A fluid inlet and an A fluid outlet. Then, a mounting hole for installing the positioning tube 3 is opened on the side of the outer tube 2, and one end of the positioning tube 3 is inserted into the mounting hole. One end of the positioning tube 3 is against the side of the inner tube 5. Laser welding is performed from the inside of the inner tube 5 to weld and fix the inner tube 5 and the positioning tube 3. Finally, laser welding is completed at the mounting holes of the positioning tube 3 and the outer tube 2 on the outside of the positioning tube 3. The positioning tube 3 is used to fix the outer tube 2 and the inner tube 5 together.

[0052] Specifically, a through hole (installation hole) is opened on the side of the outer tube 2 , the outer side of the positioning tube 3 is welded to the edge of the through hole to form an outer welding portion 7 , and the inner side of the positioning tube 3 is welded to the inner tube 5 to form an inner welding portion 8 .

[0053] One of the methods is: fluid B is the liquid that needs to be heated, and fluid A is the heating fluid. In order to ensure efficient and stable supply of fluid B that meets the temperature requirements, the cross-sectional area of ​​the annular flow channel needs to be designed to be larger, and the liquid flow rate in the annular flow channel needs to be designed to be larger. The problem caused by the larger cross-sectional area of ​​the annular flow channel and the larger liquid flow rate in the annular flow channel is that the actual heat exchange efficiency of the fluid is lower. The problem caused by the larger cross-sectional area of ​​the annular flow channel is that the liquid near the outer part of the outer tube 2 cannot be well heat exchanged; the design of the spiral shell and tube heat exchanger makes the fluid B turbulent inside the annular flow channel, ensuring uniform heat exchange of the fluid B; the design of the spiral shell and tube heat exchanger increases the heat exchange time of the fluid B in the annular flow channel, which can ensure that the fluid B is heated to a predetermined temperature.

[0054] Specifically, the diameter of the outer tube 2 is 2-3 times the diameter of the inner tube 5. The space between the inner tube 5 and the outer tube 2 is large, which can provide a larger fluid cross-section. The diameter of the inner tube 5 is 10-25CM, and the inner diameter of the positioning tube 3 is not less than 5CM, so that the laser head can be inserted into the positioning tube 3 to complete the welding operation.

[0055] In one embodiment, a blocking block 9 is fixedly installed inside the positioning tube 3. The welding quality of the positioning tube 3 and the inner tube 5 may be poor due to the influence of space. Using the blocking block 9 to seal the inside of the positioning tube 3 can prevent liquid from penetrating into the positioning tube 3 and then leaking.

[0056] Embodiment 2:

[0057] Reference Figure 5-Figure 9 The difference from the above-mentioned embodiment 1 is that: the shell and tube heat exchanger structure has multiple groups, the spiral radius of the outer tube 2 and the inner tube 5 of the multiple groups of shell and tube heat exchanger structures decreases, the multiple groups of shell and tube heat exchanger structures are arranged from the outside to the inside, the inner tube 5 of the multiple groups of shell and tube heat exchanger structures are linearly connected through the first outer tube disk connecting pipe 20, and the annular flow channels of the multiple groups of shell and tube heat exchanger structures are linearly connected through the second outer tube disk connecting pipe 21. The multiple shell and tube heat exchanger structures are distributed in the above manner to better utilize the space and further extend the actual length of the heat exchange pipeline. The multi-shell heat exchanger as a whole has A fluid inlet 10, A fluid outlet 12, B fluid inlet 13, and B fluid outlet 11, and the first outer tube disk connecting pipe 20 is U-shaped.

[0058] That is, multiple sets of shell-and-tube heat exchanger structures are connected in series, which can further extend the actual length of the heat exchange pipeline.

[0059] Embodiment three:

[0060] The difference from the above-mentioned embodiment 1 is that: the shell and tube heat exchanger structure has multiple groups, the spiral radius of the outer tube and the inner tube of the multiple groups of shell and tube heat exchanger structures decreases, and the multiple groups of shell and tube heat exchanger structures are arranged from the outside to the inside. The multiple shell and tube heat exchanger structures are distributed in the above manner to better utilize the space; each group of shell and tube heat exchangers has an A fluid inlet, an A fluid outlet, a B fluid inlet, and a B fluid outlet.

[0061] That is, multiple sets of shell-and-tube heat exchanger structures are connected in parallel (not shown in the drawings), which can synchronously realize heat exchange of multiple streams of liquid, thereby enabling a stable supply of liquid.

[0062] Specifically, the heat-insulating structure includes: an inner cylinder 15 located inside the shell-and-tube heat exchanger structure, an outer cylinder 14 located outside the shell-and-tube heat exchanger structure, and a heat-insulating spiral fin plate 19 .

[0063] A thermal insulation cotton layer 16 is fixedly provided on the inner side of the inner cylinder 15, and the thermal insulation cotton layer 16 is used to increase the thermal insulation of the inner cylinder 15. The top of the curved side panel 1 is fixedly connected with a cross brace 17, and the cross brace 17 is used to connect multiple curved side panels 1. The bottom end of the curved side panel 1 is fixedly connected with a base 18, and the base 18 plays a supporting role. The bottom ends of the outer cylinder 14 and the inner cylinder 15 are fixedly connected to the base 18. The thermal insulation spiral plate 19 is attached to the top of the shell and tube heat exchanger structure, and the outer side of the thermal insulation spiral plate 19 is fixedly connected to the outer cylinder 14, and the inner side of the thermal insulation spiral plate 19 is fixedly connected to the inner cylinder 15.

[0064] In this solution, the heat-insulating spiral sheet 19, the inner cylinder 15, and the outer cylinder 14 form an annular space, and the annular body formed by the multi-tube heat exchanger structure is located inside the annular space, thereby achieving a heat-insulating effect.

[0065] In one embodiment, the base 18 includes: a ring-shaped member 1801, on which a widened portion 1802 is provided, and the widened portion 1802 can connect multiple arc-shaped side panels 1, the top of the widened portion 1802 of the ring-shaped member 1801 is fixedly connected to the bottom end of the arc-shaped side panel 1, and the bottom of the widened portion 1802 of the ring-shaped member 1801 is fixedly connected to a supporting foot 1803.

[0066] In one embodiment, the thermal insulation spiral sheet plate 19 has a spiral angle of 380°-420°. Generally, the thermal insulation spiral sheet plate 19 is greater than 360°. The thermal insulation spiral sheet plate 19 is welded by multiple groups of short sheets less than 120°. Multiple groups of short sheets less than 120° are easy to install. After the installation positions are aligned, they are welded and fixed to form the thermal insulation spiral sheet plate 19.

[0067] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A spiral tube-type heat exchanger, comprising an outer tube (2) and an inner tube (5), wherein the inner tube (5) is located inside the outer tube (2), and the inner tube (5) and the outer tube (2) form a tube-type heat exchanger structure, characterized in that: The outer tube (2) and the inner tube (5) are spiral coils with equal spiral radius and equal spiral pitch, and further include: A positioning tube (3), one end of which passes through the outer tube (2), and the positioning tube (3) is fixed to the outer wall of the inner tube (5) by welding, and the positioning tube (3) is fixed to the outer tube (2) by welding; An arc-shaped side plate (1), wherein a positioning hole (6) is opened on the side of the arc-shaped side plate (1), the positioning tube (3) is fixedly inserted into the inside of the positioning hole (6), and the bottom of the arc-shaped side plate (1) is fixedly connected to a support seat (4); A plurality of positioning tubes (3) are provided, and the plurality of positioning tubes (3) are equidistantly distributed along the linear length direction of the outer tube (2) and the inner tube (5); The heat preservation component is an annular cylindrical structure of the shell and tube heat exchanger, and the heat preservation component is arranged on the inner side, the outer side and the end of the shell and tube heat exchanger structure.

2. A spiral tube heat exchanger according to claim 1, characterized in that: The shell-and-tube heat exchanger structure comprises a plurality of groups, the spiral radii of the outer tubes (2) and the inner tubes (5) of the plurality of groups of shell-and-tube heat exchanger structures decrease gradually, the plurality of groups of shell-and-tube heat exchanger structures are arranged in a shell-and-tube arrangement from the outside to the inside, the plurality of groups of inner tubes (5) of the shell-and-tube heat exchanger structures are linearly connected via a first outer tube coil connecting pipe (20), and the plurality of groups of annular flow passages of the shell-and-tube heat exchanger structures are linearly connected via a second outer tube coil connecting pipe (21); The whole formed by multiple sets of shell-and-tube heat exchangers has an A fluid inlet (10), an A fluid outlet (12), a B fluid inlet (13), and a B fluid outlet (11).

3. The spiral tube heat exchanger according to claim 2, characterized in that: The thermal insulation structure comprises: An inner cylinder (15) located inside the shell-and-tube heat exchanger structure, wherein a heat-insulating cotton layer (16) is fixedly disposed inside the inner cylinder (15); An outer cylinder (14) located outside the shell-and-tube heat exchanger structure, the top end of the arc-shaped side plate (1) is fixedly connected to a cross brace (17), the bottom end of the arc-shaped side plate (1) is fixedly connected to a base (18), and the bottom ends of the outer cylinder (14) and the inner cylinder (15) are both fixedly connected to the base (18); The heat-insulating spiral fin plate (19) is attached to the top of the shell-and-tube heat exchanger structure, and the outer side of the heat-insulating spiral fin plate (19) is fixedly connected to the outer cylinder (14), and the inner side of the heat-insulating spiral fin plate (19) is fixedly connected to the inner cylinder (15).

4. The spiral tube heat exchanger according to claim 3, characterized in that: The base (18) comprises: an annular member (1801), the annular member (1801) being provided with a widened portion (1802), the top of the widened portion (1802) of the annular member (1801) being fixedly connected to the bottom end of the arc-shaped side plate (1), and the bottom of the widened portion (1802) of the annular member (1801) being fixedly connected to a supporting foot (1803).

5. The spiral tube heat exchanger according to claim 3, characterized in that: The heat-insulating spiral sheet plate (19) has a spiral angle of 380°-420°, and the heat-insulating spiral sheet plate (19) is welded from a plurality of groups of short sheets with an angle less than 120°.

6. The spiral tube heat exchanger according to claim 1, characterized in that: A through hole is provided on the side of the outer tube (2); the outer side of the positioning tube (3) is welded to the edge of the through hole to form an outer welding portion (7); and the inner side of the positioning tube (3) is welded to the inner tube (5) to form an inner welding portion (8).

7. The spiral tube heat exchanger according to claim 6, characterized in that: A blocking block (9) is fixedly installed inside the positioning tube (3).

8. The spiral tube heat exchanger according to claim 1, characterized in that: The diameter of the outer tube (2) is 2-3 times the diameter of the inner tube (5), the diameter of the inner tube (5) is 10-25CM, and the inner diameter of the positioning tube (3) is not less than 5CM.

9. The spiral tube heat exchanger according to claim 2, characterized in that: The first outer tube disc connecting pipe (20) is U-shaped.

10. The spiral tube heat exchanger according to claim 1, characterized in that: The shell-and-tube heat exchanger structure has a plurality of groups, the spiral radii of the outer tubes (2) and the inner tubes (5) of the plurality of groups of shell-and-tube heat exchanger structures decrease gradually, and the plurality of groups of shell-and-tube heat exchanger structures are arranged from the outside to the inside; Each group of the double-tube heat exchangers has an A fluid inlet (10), an A fluid outlet (12), a B fluid inlet (13), and a B fluid outlet (11).

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