Fin tube and heat exchanger

Abstract

The present invention provides a fin tube and a heat exchanger, wherein the fin tube comprises a base tube, and a plurality of fin groups arranged along the axial direction of the base tube and connected to the outer wall of the base tube, and the fin groups are arranged in parallel; the fin group comprises two mirror-image fins; along the length direction of the fin, the fin is divided into three parts, the first part is the windward area, the second part is the reflow area, and the third part is the leeward area; the windward area is provided with a vortex generator, the reflow area is provided with a reflow blocking device, and the end of the leeward area is a rounded structure. The windward area has better heat exchange conditions, and has better heat exchange capacity after adding a vortex generator. The reflow area has a reflow blocking device, which can reduce the reflow, or even eliminate the reflow, and reduce dust accumulation. The heat exchange effect of the leeward area is poor, and there is more dust accumulation, so a rounded structure is adopted for the reflow to effectively reduce the flow resistance.

Description

Technical Field

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

[0002] Energy is an important foundation for human economic and social progress. With the continuous growth of energy consumption in my country, energy conservation and emission reduction have become a long-term policy for my country's economic and social development. Thermal power plants account for the largest proportion in the power industry, and it is very urgent to improve the energy efficiency of thermal power units. Thermal power plants usually set up economizers to recover flue gas waste heat to achieve the purpose of energy saving. It is a common way to increase the heat exchange area of ​​heat exchange tubes by adding fins to enhance heat exchange. H-type finned tubes have a high fin coefficient, good heat transfer performance, and strong anti-ash deposition ability. They are widely used in waste heat boilers, power station boilers and various industrial heat exchangers.

[0003] In actual production practice, the flue gas entering the heat exchanger often carries a large amount of fly ash. When the flue gas flows in the H-type fin tube bundle, there will be obvious airflow separation and recirculation area on the leeward side of the fin tube. The flue gas velocity inside the recirculation area is low, the heat exchange effect will be reduced, and ash accumulation is easy to occur. Since the thermal conductivity of ash accumulation is very low, as the degree of ash accumulation increases, the heat exchange performance of the fin tube further deteriorates, and the heat exchanger cannot operate efficiently and safely. Summary of the invention

[0004] The first object of the present invention is to provide a fin tube, which can solve the problem of serious dust accumulation in the heat exchanger in the prior art;

[0005] A second object of the present invention is to provide a heat exchanger, which uses the heat exchanger as described above.

[0006] The present invention provides a fin tube, which comprises a base tube and a plurality of fin groups arranged along the axial direction of the base tube and connected to the outer wall of the base tube, wherein the fin groups are arranged in parallel;

[0007] The fin group includes two fins arranged in a mirror image;

[0008] Along the length direction of the fin, the fin is divided into three parts, the first part is the windward area, the second part is the recirculation area, and the third part is the leeward area;

[0009] The windward area is provided with a vortex generator, the reflow area is provided with a reflow blocking device, and the end of the leeward area is a rounded structure.

[0010] Preferably, the backflow blocking device comprises a baffle plate arranged on the fin, and the maximum surface of the baffle plate is arranged parallel to the width direction of the fin.

[0011] Preferably, along the width direction of the fin, the baffle is arranged close to the base tube, and the baffle is located at 1 / 3 of the width direction of the fin;

[0012] The length of the baffle along the axial direction of the base tube is 1 / 4-1 / 3 of the spacing between adjacent fin groups.

[0013] Preferably, the vortex generator is a folded edge arranged at one end of the fin close to the air inlet direction;

[0014] The length of the longest position of the folded edge along the axial direction of the base tube is 1 / 3 of the spacing between adjacent fin groups.

[0015] Preferably, the angle of attack between the extension direction of the vortex generator and the airflow direction is 10° to 90°.

[0016] Preferably, the area of ​​the windward region is larger than the area of ​​the leeward region.

[0017] Preferably, the fin tube includes 2-4 base tubes, and the base tubes are arranged in parallel.

[0018] A heat exchanger comprises a shell, in which the finned tube as described above is arranged;

[0019] Along the flow direction of the airflow, the shell is divided into an ash accumulation section and a heat exchange section;

[0020] The ash accumulation section and the heat exchange section are both provided with a ash blowing device and an ash cleaning tank.

[0021] Preferably, in the housing, the fin tubes are arranged in a horizontal direction, and the axial direction of the fin tubes is perpendicular to the airflow direction;

[0022] In the dust accumulation section, the arrangement spacing between the upper fin tubes is smaller than the arrangement spacing between the lower fin tubes.

[0023] Preferably, the number of soot blowing devices located in the soot accumulation section is 2-3 times the number of soot blowing devices located in the heat exchange section.

[0024] Beneficial effects:

[0025] The windward area has better heat exchange conditions, and has better heat exchange capacity after adding the vortex generator. The reflow area has a reflow blocking device, which can reduce or even eliminate the reflow and reduce dust accumulation. The leeward area has poor heat exchange effect and more dust accumulation, so the rounded corner structure is used for the reflow to effectively reduce the flow resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A front view of the minimum repeating unit of a fin tube provided in a specific embodiment of the present invention;

[0028] Figure 2 A top view of a minimum repeating unit of a fin tube provided in a specific embodiment of the present invention;

[0029] Figure 3 A schematic diagram of the structure of a heat exchanger provided in a specific embodiment of the present invention;

[0030] Figure 4 A schematic diagram of the structure of staggered arrangement of finned tubes provided in a specific embodiment of the present invention.

[0031] Description of reference numerals:

[0032] 1: fin tube; 2: ash accumulation section; 3: heat exchange section; 5: soot blowing device; 6: soot cleaning tank; 7: inlet section; 8: outlet section;

[0033] 11: base tube; 12: fin; 13: vortex generator; 14: backflow barrier; 15: rounded corner structure. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than 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.

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0036] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] like Figures 1 to 4 As shown, in this embodiment, a fin tube is provided, wherein the fin tube 1 comprises a base tube 11, and a plurality of fin groups arranged axially along the base tube 11 and connected to the outer wall of the base tube, and the fin groups are arranged in parallel. The fin group comprises two mirror-image fins 12, and along the length direction of the fin 12, the fin 12 is divided into three parts, the first part is the windward area, the second part is the recirculation area, and the third part is the leeward area, the windward area is provided with a vortex generator 13, the recirculation area is provided with a recirculation barrier 14, and the end of the leeward area is a rounded structure 15.

[0038] The windward area has better heat exchange conditions, and has better heat exchange capacity after adding the vortex generator 13. The reflow area has a reflow blocking device 14, which can reduce or even eliminate the reflow and reduce dust accumulation. The leeward area has a poor heat exchange effect and more dust accumulation, so a rounded corner structure 15 is used for the reflow to effectively reduce the flow resistance.

[0039] The backflow blocking device includes a baffle plate arranged on the fin 12, and the maximum surface of the baffle plate is arranged parallel to the width direction of the fin. The baffle plate arranged on the fin 12 is stamped, and holes are first punched on the fin, and the punched structure is folded to form the baffle plate. One baffle plate or two baffle plates can be arranged on the fin 12. When two baffle plates are arranged on the fin 12, the two baffle plates are respectively located on both sides of the fin 12.

[0040] Along the width direction of the fin 12, the baffle is arranged close to the base tube 11, and the baffle is located at 1 / 3 of the width direction of the fin.

[0041] The length of the baffle along the axial direction of the base tube 12 is 1 / 4-1 / 3 of the distance between adjacent fin groups.

[0042] During the use of the finned tube, the baffle has a blocking effect on the airflow, which can reduce the reflow area or even eliminate the reflow and reduce dust accumulation.

[0043] The vortex generator 13 is a folded edge arranged at one end of the fin 12 close to the air inlet direction, and the length of the folded edge at the longest position along the axial direction of the base tube 11 is 1 / 3 of the spacing between adjacent fin groups. The angle of attack between the extension direction of the vortex generator 13 and the airflow direction is 10° to 90°.

[0044] The vortex generator 13 is formed by bending fins and is easy to manufacture.

[0045] The area of ​​the windward area is larger than that of the leeward area. Specifically, the area of ​​the windward area is 2-3 times the area of ​​the leeward area.

[0046] The heat exchange effect in the leeward area is poor and there is more dust accumulation, so a rounded corner arrangement is adopted for the reflux to effectively reduce the flow resistance.

[0047] The fin 12 moves toward the windward area as a whole, increasing the area of ​​the windward area while reducing the area of ​​the leeward area, thereby further enhancing the heat exchange effect.

[0048] The fin tube 1 comprises 2-4 base tubes 11, and the base tubes 11 are arranged in parallel, that is, it comprises double H-type fin tubes, triple H-type fin tubes and quadruple H-type fin tubes.

[0049] The surface shape of the fin 12 can be a rectangle, a parallelogram, a trapezoid or an irregular trapezoid. The inner side of the fin 12 has an arc groove that matches the outer wall of the base tube 11, and the fin 12 is connected to the base tube 11 through the arc groove.

[0050] In summary, in this embodiment, the fin tube provides the following advantages:

[0051] The windward area has better heat exchange conditions. By setting the vortex generator 13, the fins away from the base tube 11 are offset in the direction of the airflow, which can effectively deal with the wear of the flue gas. At the same time, the vortex generator 13 formed by the bend can effectively enhance the heat exchange effect. The recirculation area is prone to flue gas flow separation and recirculation. The recirculation increases the time that the flue gas and the fin tube are heated. The flue gas temperature in the recirculation area is high and cannot be quickly diffused to the area outside the recirculation area, so the heat exchange effect is reduced. The flue gas velocity in the center of the recirculation area is low, which makes it easy for the particles in the flue gas to settle out of the flue gas. Because the particles in the flue gas are charged due to the friction between the particles in the flue gas and the front heat exchanger, they are easily adsorbed on the fins and gradually accumulate to form a blockage. In this embodiment, the baffle has a blocking effect on the airflow, which can reduce the recirculation area or even eliminate the recirculation and reduce ash accumulation. The leeward area has a poor heat exchange effect and more ash accumulation due to the obstruction of the base pipe, which significantly reduces the flue gas flow rate in this area. The fins move toward the windward area as a whole, which can increase the area of ​​the windward area while reducing the area of ​​the leeward area. Compared with the single H-type fin, the multi-H-type fin has the characteristics of simple process, convenient processing, and efficient welding.

[0052] Reference Figure 3 , Figure 4In this embodiment, a heat exchanger is also provided, which includes a shell, and the fin tube 1 as described above is arranged in the shell.

[0053] Along the flow direction of the airflow, the shell is divided into an ash accumulation section 2 and a heat exchange section 3 , and both the ash accumulation section 2 and the heat exchange section 3 are provided with a ash blowing device 5 and an ash cleaning tank 6 .

[0054] The shell further comprises an inlet section 7 and an outlet section 8. The inlet section 7, the dust accumulation section 2, the heat exchange section 3 and the outlet section 8 are arranged in sequence along the air flow direction.

[0055] The inlet section 7 is a bell-mouth structure, and the larger opening of the inlet section 7 is connected to the ash accumulation section 2. After the flue gas passes through the inlet section 7, the cross-sectional area of ​​the flow channel becomes larger, the flue gas velocity decreases, the wear of the flue gas on the fin tube 1 is reduced, and the ash is more likely to accumulate in the ash accumulation section.

[0056] The fin tubes 1 are arranged in the horizontal direction, and the axial direction of the fin tubes 1 is perpendicular to the airflow direction. In the dust accumulation section 2, the arrangement spacing between the upper fin tubes 1 is smaller than the arrangement spacing between the lower fin tubes 1.

[0057] Due to the influence of gravity, dust accumulation at lower heights is often greater than that at higher heights. Therefore, increasing the spacing between the finned tubes 1 is beneficial to preventing dust accumulation from blocking the flow channel.

[0058] The number of soot blowing devices 5 located in the soot accumulation section 2 is 2-3 times the number of soot blowing devices 5 located in the heat exchange section 3. The fin tubes 1 are arranged in an interlaced arrangement, that is, staggered arrangement of fins is formed.

[0059] The experiment found that the wear of the pipeline is proportional to the cube of the flue gas velocity. Therefore, increasing the flow area and increasing the flow resistance can reduce the flue gas velocity. The staggered arrangement of the fins can further increase the resistance of the flow channel, thereby reducing wear. The experiment also found that most of the dust accumulation occurs in the first few rows of tube bundles, and there is only a small chance for the tube bundles at the rear of the flow channel. Therefore, the dust accumulation in the first few rows of tube bundles of the flow channel should be cleaned in time. Since the dust accumulation in the first few rows of tube bundles is much more serious than that in the rear tube bundles, the soot blowing devices should be arranged more densely at the rear and used more frequently than the rear rows.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A finned tube, characterized in that: The fin tube comprises a base tube, and a plurality of fin groups arranged along the axial direction of the base tube and connected to the outer wall of the base tube, wherein the fin groups are arranged in parallel; The fin group includes two fins arranged in a mirror image; Along the length direction of the fin, the fin is divided into three parts, the first part is the windward area, the second part is the recirculation area, and the third part is the leeward area; The windward area is provided with a vortex generator, the recirculation area is provided with a recirculation barrier, and the end of the leeward area is a rounded structure; The vortex generator is a folded edge arranged at one end of the fin close to the air inlet direction; The longest length of the folded edge along the axial direction of the base tube is 1 / 3 of the spacing between adjacent fin groups; The backflow blocking device comprises a baffle plate arranged on the fin, wherein the maximum surface of the baffle plate is arranged parallel to the width direction of the fin; Along the width direction of the fin, the baffle is arranged close to the base tube, and the baffle is located at 1 / 3 of the width direction of the fin; The length of the baffle along the axial direction of the base tube is 1 / 4-1 / 3 of the spacing between adjacent fin groups; The angle of attack between the extension direction of the vortex generator and the airflow direction is 10° to 90°; The fin tube comprises 2-4 base tubes, and the base tubes are arranged in parallel.

2. The fin tube according to claim 1, characterized in that: The area of ​​the windward region is larger than that of the leeward region.

3. A heat exchanger, characterized in that: It comprises a shell, in which the fin tube according to any one of claims 1 to 2 is arranged; Along the flow direction of the airflow, the shell is divided into an ash accumulation section and a heat exchange section; The ash accumulation section and the heat exchange section are both provided with a ash blowing device and an ash cleaning tank.

4. The heat exchanger according to claim 3, characterized in that In the shell, the fin tubes are arranged in a horizontal direction, and the axial direction of the fin tubes is perpendicular to the airflow direction; In the dust accumulation section, the arrangement spacing between the upper fin tubes is smaller than the arrangement spacing between the lower fin tubes.

5. The heat exchanger according to claim 3, characterized in that: The number of soot blowers located in the soot accumulation section is 2-3 times the number of soot blowers located in the heat exchange section.

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