Finned tube with narrow gap channels

Abstract

The utility model relates to a finned tube with narrow-gap channels, which can be used for a combustion head for gas premixing combustion and can also be used for backfire prevention of a flame arrester. The heat exchanger comprises a fin and a base tube, the base tube is a round tube, the fin is spirally and evenly wound on the outer wall of the base tube through a flat steel belt, the fin comprises a fin root and a fin tip, the fin root and the outer wall of the base tube are welded through laser, the upper side and the lower side of the fin tip are original arcs, and the fin root and the fin tip are arc-shaped. The fin is structurally characterized in that the left side and the right side of the fin tip are pressed and formed into new arcs through a die, the new arcs are connected with original arcs through straight sections, narrow gap channels are formed between the adjacent fins and the outer wall of the base tube after pressing and forming, and the sections of the fins before pressing and forming are of an annular structure. After compression molding, overlapped parts exist between the adjacent fins, all fin tips incline towards the same direction, and the circle center of the new arc coincides with the circle center of the original arc.

Description

Technical Field

[0001] The utility model relates to a fin tube with a narrow gap channel, which can be used for a combustion head of gas premix combustion and can also be used for a flame arrester to prevent backfire. Background Art

[0002] Natural gas is currently the most widely used gas fuel. In modern times where energy conservation and environmental protection are advocated, efficient and clean combustion of natural gas is particularly important.

[0003] Premixed combustion is a method of mixing gas and air before combustion to make them evenly distributed before sending them into the burner for combustion. It has the characteristics of low excess oxygen, high combustion efficiency, good energy saving effect, and low nitrogen oxide emissions. At present, the main types of burners suitable for premixed combustion on the market are as follows:

[0004] 1. Metal fiber surface burner. High temperature resistant metal fibers are woven into a mesh, and the mixed gas is ejected from the mesh holes, and the metal fiber mesh is cooled by the mixed gas. The mesh holes are very fine, comparable to a hair, and the thickness is very thin. The mesh holes are easily blocked, causing overheating damage and easy to backfire.

[0005] 2. Tubular burner head. Gaps are formed between round tubes or square tubes (or inner round and outer square tubes), and the mixed gas is ejected from the equally spaced gaps. The gap length of the round tube type is limited, and when a deflagration or other accident occurs, it is easy to flash back. The square tube gap is longer than the round tube gap, and it is not easy to flash back, but it is necessary to arrange additional light tubes in the direction of the flame ejection to form a reflow zone to prevent the flame from flameout under high load. When the tube is under pressure, according to the boiler industry standards, stainless steel cannot be used, and carbon steel pipes must be used. Carbon steel pipes are not resistant to acid corrosion. When gas is burned, weak acid condensate will be produced. In order to prevent acid corrosion, a special coating needs to be sprayed on the outer wall of the tube to prevent the size of the gap from changing due to corrosion. The process is complicated and the cost is high. Utility Model Content

[0006] The utility model aims to overcome the above-mentioned deficiencies in the prior art and to provide a fin tube with a reasonably designed structure and a narrow gap channel. The burner head made of the fin tube has the characteristics of anti-flashback, anti-fireout, compact structure, high safety and stability, etc.

[0007] The technical solution adopted by the utility model to solve the above problems is: the fin tube with narrow gap channel comprises fins and a base tube, the base tube is a round tube, the fins are made of flat steel strips spirally and evenly wound on the outer wall of the base tube, the fins comprise wing roots and wing tips, the wing roots and the outer wall of the base tube are laser welded, the upper and lower sides of the wing tips are original arcs, and the structural feature is that the left and right sides of the wing tips are pressed and formed into new arcs by a mold, the new arcs are connected to the original arcs by a straight section, and a narrow gap channel is formed between adjacent fins and the outer wall of the base tube after pressing and forming.

[0008] Furthermore, the cross section of the fin before pressing and forming is arranged in a circular ring structure.

[0009] Furthermore, after press forming, there are overlapping portions between adjacent fins.

[0010] Furthermore, after press forming, all wing tips are tilted in the same direction.

[0011] Furthermore, the center of the new arc coincides with the center of the original arc.

[0012] Furthermore, the symmetry axes of the two new arcs are arranged perpendicular to the symmetry axes of the two original arcs.

[0013] Furthermore, the straight section and the outer wall of the base pipe form a flared structure.

[0014] Furthermore, the diameter of the new arc is d2, the diameter of the original arc is d3, and d2<d3.

[0015] Furthermore, the length of the narrow gap channel is equal to the length of the new arc, and the length of the new arc is s.

[0016] Furthermore, the pitch of the fin is p, the value range of p is 1 to 4 mm, the thickness of the fin is t, the value range of t is 0.2 to 1.5 mm, and the height of the fin is h, the value range of h is 3 to 10 mm.

[0017] Compared with the prior art, the utility model has the following advantages:

[0018] 1. It has a narrow gap channel, the equivalent diameter of which is smaller than the quenching diameter of the flame, and the length of which is greater than the quenching length of the flame, and has an automatic anti-flashback function.

[0019] 2. The narrow gap channel is arc-shaped. Compared with round tubes or square tubes, to achieve the same quenching length, a smaller base tube diameter can be used than a round tube or square tube, and the structure is more compact.

[0020] 3. The straight section and the base pipe form an expansion. When the flow rate of the mixed gas changes, the flame root moves in the expansion direction and adapts to the change of the flow rate. The flame root will not run out of the arc of the original arc to prevent flameout.

[0021] 4. The fin root and the base tube are welded by laser welding, which has good fusion and low thermal resistance. Heat can be quickly transferred from the fin to the base tube, and the cooling capacity is strong.

[0022] 5. Cooling water flows inside the base tube, which can absorb the heat transferred from the fins, making the fin temperature lower. During tempering, the temperature of the flame in the channel can be reduced more quickly to extinguish the flame. At the same time, under normal circumstances, it can also absorb part of the heat radiated by the flame to heat the cooling water in the tube, reduce the flame temperature, and reduce the amount of nitrogen oxides generated.

[0023] 6. When the base tube is under pressure, the base tube is made of carbon steel, and the fins can be made of acid-resistant stainless steel, thereby enhancing the acid corrosion resistance, eliminating the need for special coatings, and having low costs and long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the main structure of the finned tube after being pressed and formed according to an embodiment of the utility model.

[0025] Figure 2 It is a schematic diagram of the top view of the fin tube after being pressed and formed according to an embodiment of the utility model.

[0026] Figure 3 yes Figure 1 Schematic diagram of the AA section structure.

[0027] Figure 4 yes Figure 1 Schematic diagram of the BB cross-section structure.

[0028] Figure 5 yes Figure 4 Schematic diagram of the enlarged structure of part C in.

[0029] Figure 6 It is a schematic diagram of the main structure of the finned tube before being pressed and formed according to an embodiment of the utility model.

[0030] Figure 7 It is a left-side structural schematic diagram of the fin tube before pressing and forming according to an embodiment of the utility model.

[0031] In the figure: fin 1, base tube 2, narrow gap channel 3, original arc 11, straight section 12, new arc 13, wing root 14, wing tip 15. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and through examples. The following examples are provided to explain the present invention, but the present invention is not limited to the following examples.

[0033] Example

[0034] See also Figures 1 to 7 As shown, it should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the utility model, so they have no substantial technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects and purposes that can be achieved by the utility model, should still fall within the scope of the technical content disclosed by the utility model. At the same time, if there are references to terms such as "upper", "lower", "left", "right", "middle" and "one" in this specification, they are only for the convenience of description, and are not used to limit the scope of the implementation of the utility model. The change or adjustment of their relative relationship, without substantially changing the technical content, should also be regarded as the scope of the implementation of the utility model.

[0035] The fin tube with narrow gap channels in this embodiment includes fins 1 and a base tube 2. The base tube 2 is a round tube made of carbon steel, stainless steel, or other materials, which is determined according to the usage. The fins 1 are formed by a flat steel strip evenly wound spirally around the outer wall of the base tube 2. The fins 1 are approximately perpendicular to the outer wall of the base tube 2, and cooling water can flow through the base tube 2.

[0036] The fin 1 includes a wing root 14 and a wing tip 15. The wing root 14 and the outer wall of the base tube 2 are integrated by laser welding. After the welding is completed, the wing tip 15 is pressed and formed by a mold. The left and right sides of the wing tip 15 are pressed and formed by a mold to form a new arc 13 (such as Figure 3 As shown in the figure, the pitch of fin 1 is p, the value range of p is 1 to 4 mm, the thickness of fin 1 is t, the value range of t is 0.2 to 1.5 mm, and the height of fin 1 is h, the value range of h is 3 to 10 mm.

[0037] The cross section of the fin 1 before pressing is in a circular ring structure, and the upper and lower sides of the wing tip 15 are the original arc 11 (such as Figure 7 As shown in FIG. 1 ), the diameter of the new arc 13 is d2, the diameter of the original arc 11 is d3, d2<d3, after pressing, there are overlapping parts between adjacent fins 1, and all fin tips 15 are tilted in the same direction, and a narrow gap channel 3 is formed between the outer wall of the adjacent fins 1 and the base tube 2 (as shown in FIG. Figure 5As shown in FIG. 1 ), the length of the narrow gap channel 3 is equal to the length of the new arc 13, the length of the new arc 13 is s, the center of the new arc 13 coincides with the center of the original arc 11, and the new arc 13 is connected to the original arc 11 by a straight segment 12 (as shown in FIG. 1 ). Figure 3 As shown in FIG. 1 ), the straight section 12 forms a flared structure with the outer wall of the base pipe 2 , and the symmetry axes of the two new circular arcs 13 are arranged perpendicular to the symmetry axes of the two original circular arcs 11 .

[0038] Pressed front fin 1 (such as Figure 6 As shown in the figure, on the axial section of the finned tube, the fin 1 is almost perpendicular to the base tube 2. Before pressing, the angle between the fin 1 and the base tube 2 is α1, where α1 ≥ 85°. The fins 1 are parallel to each other and do not intersect. After pressing, the fin 1 (as shown in the figure) Figure 5 As shown in the figure, the wing tips 15 of all the fins 1 on the press-formed side are tilted in the same direction, and the adjacent fins 1 overlap each other except for a distance from the wing roots 14 as the overlapping parts. The angle between the fins 1 and the base tube 2 in the overlapping parts is the angle α2 between the fins 1 and the base tube 2 after press-forming, wherein α2≤20°, and an irregularly shaped narrow gap channel 3 is formed between the adjacent fins 1 and the outer walls of the base tube 2, and the length of the narrow gap channel 3 on the circumference is the length of the new arc 13, which is s.

[0039] The principle of anti-flashback is: when the flame moves a certain distance in a narrow channel, it will naturally extinguish, which is called quenching; there is an upper limit value for the slit spacing or the diameter of the narrow channel that can cause the flame to quench, which is called the quenching diameter; the distance the flame travels after entering the narrow channel until it is extinguished is called the quenching length. As long as the diameter of the channel is smaller than the quenching diameter and the length of the channel is greater than the quenching length, flashback can be prevented.

[0040] In order to have the function of automatically preventing flashback, the length of the narrow gap channel 3 should be greater than the quenching length of the corresponding gas flame, and the equivalent diameter of the narrow gap channel 3 should be smaller than the quenching diameter of the corresponding gas flame.

[0041] When used on a burner, a mixture of gas and air enters from a flared opening formed by a straight section 12 at one end and the outer surface of a corresponding base tube 2, and is then ejected from a flared opening formed by a straight section 12 at the other end and the outer surface of the corresponding base tube 2, and then ignites and burns. Since the cross-sectional area of ​​the flared opening is not fixed but gradually increases, when the combustion load increases, the root of the flame will move from a small flared opening section to a large flared opening section section, and the root of the flame is always within the range of the flared opening, thereby automatically preventing the flame from flameout.

[0042] When used in a burner, water may flow through the interior of the base tube 2 to achieve better cooling effect, lower flame temperature, and less nitrogen oxide generation.

[0043] Among them: the length of the new arc 13 is s, the length of the straight section 12 is L, the diameter of the base tube 2 is d1, the diameter of the new arc 13 is d2, the diameter of the original arc 11 is d3, the pitch of the fin 1 is p, the thickness of the fin 1 is t, the height of the fin 1 is h, the angle between the fin 1 and the base tube 2 before pressing is α1, and the angle between the fin 1 and the base tube 2 after pressing is α2.

[0044] The length s of the new arc 13 is greater than the quenching length of the corresponding gas flame; the equivalent diameter of the narrow gap channel 3 is smaller than the quenching diameter of the corresponding gas flame; water can flow through the inside of the base tube 2 to achieve better cooling effect, lower flame temperature and less nitrogen oxide generation.

[0045] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is only an example of the structure of the utility model. All equivalent changes or simple changes made based on the structure, features and principles described in the patent concept of the utility model are included in the protection scope of the utility model patent. Technicians in the technical field of the utility model can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the utility model or exceed the scope defined by the claims, they should all fall within the protection scope of the utility model.

Claims

1. A fin tube with a narrow gap channel, comprising a fin (1) and a base tube (2), wherein the base tube (2) is a round tube, the fin (1) is made of a flat steel strip evenly wound in a spiral shape on the outer wall of the base tube (2), the fin (1) comprises a fin root (14) and a fin tip (15), the fin root (14) and the outer wall of the base tube (2) are laser welded, and the upper and lower sides of the fin tip (15) are original arcs (11), characterized in that: The left and right sides of the wing tip (15) are pressed and formed into a new arc (13) by a mold. The new arc (13) is connected to the original arc (11) via a straight section (12). After the pressing and forming, a narrow gap channel (3) is formed between the outer walls of adjacent fins (1) and the base tube (2).

2. The fin tube with narrow gap channels according to claim 1, characterized in that: The cross section of the fin (1) before pressing and forming is arranged in a circular ring-shaped structure.

3. The fin tube with narrow gap channels according to claim 1, characterized in that: After press forming, there are overlapping portions between adjacent fins (1).

4. The fin tube with narrow gap channels according to claim 1, characterized in that: After the pressing and forming, all the wing tips (15) are tilted in the same direction.

5. The fin tube with narrow gap channels according to claim 1, characterized in that: The center of the new arc (13) coincides with the center of the original arc (11).

6. The fin tube with narrow gap channels according to claim 1, characterized in that: The symmetry axes of the two new circular arcs (13) are arranged perpendicular to the symmetry axes of the two original circular arcs (11).

7. The fin tube with narrow gap channels according to claim 1, characterized in that: The straight section (12) and the outer wall of the base pipe (2) form a flared structure.

8. The fin tube with narrow gap channels according to claim 1, characterized in that: The diameter of the new circular arc (13) is d2, the diameter of the original circular arc (11) is d3, and d2<d3.

9. The fin tube with narrow gap channels according to claim 1, characterized in that: The length of the narrow gap channel (3) is equal to the length of the new circular arc (13), and the length of the new circular arc (13) is s.

10. The fin tube with narrow gap channels according to claim 1, characterized in that: The pitch of the fin (1) is p, and the value range of p is 1 to 4 mm. The thickness of the fin (1) is t, and the value range of t is 0.2 to 1.5 mm. The height of the fin (1) is h, and the value range of h is 3 to 10 mm.

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