A heat-resistant alloy seamless pipe with different diameters, finned tube

Abstract

The present invention relates to a heat-resistant stepped seamless tube and finned tube, belonging to the field of preparation of heat exchange tubes for nuclear energy use. A heat-resistant alloy stepped seamless tube includes a regular section, a stepped section, and a stepped diameter section that have the same inner diameter and are integrally connected; the stepped diameter section and the regular section are transitionally connected through the stepped section; the outer diameter of the stepped section gradually increases along the direction from the regular section to the stepped diameter section. The present invention has the characteristics of small inner diameter deviation, short length of the transition tube body, and excellent straightness of the tube body, and can be used for a long time in a high-temperature environment above 600 °C.

Description

Technical Field

[0001] The present invention relates to a heat-resistant alloy stepped seamless tube and finned tube, belonging to the field of preparation of heat exchange tubes for nuclear energy use. Background Art

[0002] A heat pipe reactor is a fully static, passive and small-sized reactor system. However, the power level of the heat pipe reactor is relatively small compared with other third-generation and fourth-generation nuclear reactors. Therefore, it is necessary to increase the core temperature of the reactor and improve the heat exchange efficiency to reduce the unit power cost and enhance the economic competitiveness of this technology.

[0003] The core heat pipe is the core component of the reactor, and its function is to conduct the heat generated by the nuclear reaction in the core to the outside of the core for power generation. The part of the heat pipe inside the core is a steel pipe with a smooth surface, and the part outside the core is usually a steel pipe with external fins, and the heat exchange efficiency is improved by increasing the surface area. However, the nuclear power system needs to ensure absolute safety and minimize potential risks to ensure that nuclear safety accidents such as leakage do not occur in the nuclear power plant. Therefore, the design and material selection of the heat pipe are crucial for the safe operation of the heat pipe reactor.

[0004] Generally, the tubes used to manufacture finned tubes are ordinary steel pipes. According to needs, a certain number of fins are processed in a certain area of the steel pipe to meet the heat exchange requirements. However, in such conventional products and manufacturing technologies, the following problems exist:

[0005] (1) Most of the steel pipes are welded steel pipes. The weld and its heat-affected zone itself will fail due to internal defects. If they are corroded by the medium for a long time or operate under high-parameter special working conditions for a long time, the weld area is very likely to have accidents such as corrosion cracking and stress cracking.

[0006] (2) After the fins are roll-formed, the remaining wall thickness of the tube body in the fin area is thinner than that of the tube body without processed fins. After operating under high-parameter working conditions for a certain period of time, problems such as oxidation and shedding of the tube body material in the fin segment and cracking are likely to occur, resulting in accidents.

[0007] (3) The content of alloying elements in conventional materials is low, and the material's ability to withstand high-parameter operating conditions is poor. It cannot be applied to high-efficiency heat exchange equipment in the nuclear reactor core, cannot improve the operating parameters of the equipment, and thus cannot improve the overall economy of the equipment.

[0008] Aiming at the high power parameter requirements of the heat pipe reactor, the existing products and technologies cannot meet the manufacturing requirements of low-fin heat pipes. Summary of the Invention

[0009] Aiming at the deficiencies of the existing products and technologies, the present invention provides a heat-resistant alloy stepped seamless tube, which can be used to manufacture low-fin heat pipes and has the characteristics of high temperature resistance.

[0010] A heat-resistant alloy seamless pipe with different diameters, comprising a regular section, a reducing section and a different-diameter section with the same inner diameter and integrally connected; the different-diameter section and the regular section are transitionally connected through the reducing section; the outer diameter of the different-diameter section is greater than the outer diameter of the regular section, the minimum outer diameter of the reducing section is equal to the outer diameter of the regular section, the maximum outer diameter of the reducing section is equal to the outer diameter of the different-diameter section, and the outer diameter of the reducing section gradually increases along the direction from the regular section to the different-diameter section.

[0011] In the above technical solution of the present invention, the heat-resistant material refers to a high-temperature metal material that can work long-term in a temperature environment above 600 °C, and it usually has excellent high-temperature strength, good oxidation resistance and hot corrosion resistance.

[0012] The main elements of heat-resistant metals are usually iron and nickel. They are generally divided into iron-based alloys, nickel-based alloys and iron-nickel-based alloys. A corrosion-resistant alloy with nickel content > 30% and nickel + iron > 50% is customarily called an iron-nickel-based alloy.

[0013] In the above technical solution of the present invention, the inner diameter of the seamless pipe is the same for both the regular section, the reducing section and the different-diameter section; while the wall thickness value of the different-diameter section is significantly larger, which is for the convenience of post-processing into finned tubes by means of rolling or cutting, etc.

[0014] As a preference of the above technical solution, the inner diameter range of the seamless pipe is 10 mm to 28 mm, and the inner diameter deviation of the whole pipe body ≤ 0.15 mm.

[0015] As a preference of the above technical solution, the wall thickness of the different-diameter section is 1.1 to 2.4 times that of the regular section wall thickness.

[0016] As a preference of the above technical solution, the length of the reducing section ≤ 200 mm; the inside of the reducing section is a cylindrical hollow, and the outside is in the shape of a frustum of a cone.

[0017] Another object of the present invention is to provide a finned tube prepared based on the above heat-resistant seamless pipe with different diameters.

[0018] A heat-resistant finned tube, comprising a regular section, a reducing section and a different-diameter section with the same inner diameter and integrally connected; the different-diameter section and the regular section are transitionally connected through the reducing section; the outer diameter of the different-diameter section is greater than the outer diameter of the regular section, the minimum outer diameter of the reducing section is equal to the outer diameter of the regular section, the maximum outer diameter of the reducing section is equal to the outer diameter of the different-diameter section; heat-dissipating fins are arranged on the different-diameter section; the outer diameter of the reducing section gradually increases along the direction from the regular section to the different-diameter section.

[0019] As a preference of the above technical solution, the different-diameter section includes a connection end connected to the reducing section, an intermediate section provided with the heat-dissipating fins, and a tail end connecting the intermediate section.

[0020] Preferably, as the above technical solution, the wall thickness of the middle section is 0.8 to 1.2 times that of the conventional section.

[0021] Preferably, as the above technical solution, the wall thickness of the connecting end is equal to that of the tail end; the sum of the wall thickness of the middle section and the height of the heat dissipation fins is not less than the wall thickness of the connecting end.

[0022] Preferably, as the above technical solution, the heat dissipation fins are spiral strips spirally arranged on the middle section and are integrally connected to the middle section.

[0023] Preferably, as the above technical solution, the pitch and the thickness of the spiral strip of the spiral strip are flexibly adjustable. More preferably, for the spiral strip, the pitch is 0.1 to 0.3 times the outer diameter, and the thickness of the spiral strip is 0.8 to 1.2 times the pitch. The outer diameter is the diameter of the imaginary cylinder that coincides with the top of the external thread tooth.

[0024] The present invention has the following beneficial effects:

[0025] The present invention has the characteristics of small inner diameter deviation, short length of the transition pipe body, and excellent straightness of the pipe body, and can be used for a long time in a high-temperature environment above 600 °C. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of the heat-resistant alloy reducing seamless pipe of the present invention;

[0027] Figure 2 is a schematic structural diagram of the heat-resistant alloy finned pipe of the present invention;

[0028] In the figure, 1 - conventional section, 2 - reduced diameter section, 3 - reducing section, 300 - heat dissipation fins, 31 - connecting end, 32 - middle section, 33 - tail end. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention will be further described in detail below with reference to the accompanying drawings in the embodiments of the present invention.

[0030] Embodiment 1

[0031] As Figure 1 shown, a heat-resistant alloy reducing seamless pipe includes a conventional section 1, a reduced diameter section 2, and a reducing section 3 that are integrally connected; the reducing section 3 is transitionally connected to the conventional section 1 through the reduced diameter section 2; the specific dimensions are as follows:

[0032] (1) The total length of the pipe body is 6180 mm, and the inner diameter is Φ17 mm throughout the length;

[0033] (2) The outer diameter of the conventional section 1 of the pipe body is Φ19.2 mm, the wall thickness is 1.1 mm, and the length is 3000 mm;

[0034] (3) The outer diameter of the tube body of the reduced-diameter section 3 is Φ21 mm, the wall thickness is 2 mm, and the length is 3000 mm;

[0035] (4) The difference in wall thickness between the tube body of the reduced-diameter section 3 and the tube body of the conventional section 1 is 0.9 mm;

[0036] (5) The tube body of the reduced-diameter section 2 has a length of 180 mm, is cylindrical and hollow inside, and is in the shape of a frustum of a cone outside.

[0037] The chemical composition of the tube body is as follows: the mass of chromium element is 22%, the mass of cobalt element is 12%, the mass of molybdenum element is 9%, the mass of iron element is 2%, the mass of aluminum element is 1.2%, the mass of manganese element is 0.8%, the mass of copper element is 0.2%, the mass of titanium element is 0.2%, the mass of silicon element is 0.1%, the mass of carbon element is 0.08%, the mass of phosphorus element ≤ 0.012%, the mass of sulfur element ≤ 0.012%, the mass of boron element ≤ 0.006%, and the balance is nickel element.

[0038] Example Two

[0039] The seamless tube prepared in Example One is processed with fins to make a heat-resistant alloy finned tube.

[0040] As Figure 2 shown, a heat-resistant alloy finned tube includes a conventional section 1, a reduced-diameter section 2 and a reduced-diameter section 3 which are integrally connected; the reduced-diameter section 3 and the conventional section 1 are transitionally connected through the reduced-diameter section 2; heat-dissipating fins 300 are arranged on the reduced-diameter section 3. The reduced-diameter section 3 includes a connection end 31 connected to the reduced-diameter section 2, an intermediate section 32 provided with the heat-dissipating fins 300, and a tail end 33 connecting the intermediate section 32.

[0041] The heat-dissipating fins 300 are spiral strips spirally arranged on the intermediate section 32 and are integrally connected with the intermediate section 32. For the spiral strip, the pitch is 0.2 times the outer diameter, and the thickness of the spiral strip is 1.0 times the pitch.

[0042] The specifications of the superalloy finned tube are as follows:

[0043] (1) The total length of the tube body is 6180 mm, and the inner diameter is Φ17 mm throughout;

[0044] (2) The outer diameter of the tube body of the conventional section 1 is Φ19.2 mm, the wall thickness is 1.1 mm, and the length is 3000 mm;

[0045] (3) The outer diameter of the tube body of the reduced-diameter section 3 is Φ21 mm, the wall thickness is 2.0 mm, and the length is 3000 mm;

[0046] (4) The difference in wall thickness between the tube body of the reduced-diameter section 3 and the tube body of the conventional section 1 is 0.9 mm;

[0047] The body of the reduced-diameter section 2 has a length of 180 mm, is cylindrical and hollow inside, and is frustum-shaped outside;

[0048] The outer diameter of the connecting end 31 is Φ21 mm and its length is 10 mm;

[0049] The outer diameter of the middle section 32 is Φ21 mm and its length is 2980 mm;

[0050] The outer diameter of the tail end 33 is Φ21 mm and its length is 10 mm;

[0051] The height of the heat dissipation fins 300 is 1.1 mm.

[0052] The preparation method of the above heat-resistant alloy finned tube is as follows:

[0053] S1. Provide the product obtained in Example 1;

[0054] S2. Roll the fins in a manner similar to the way of making external threads on the tube body in the prior art;

[0055] S3. Heat-treat the tube body at a heat treatment temperature of 1110 °C for 10 min; after the heat preservation ends, cool the tube body to below 100 °C, and the cooling rate ≥ 100 °C / min; thus obtaining the product.

Claims

1. A heat-resistant alloy finned tube, characterized in that: It includes a regular section (1), a diameter-changing section (2), and a different-diameter section (3) that have the same inner diameter and are integrally connected; the different-diameter section (3) is transitionally connected to the regular section (1) through the diameter-changing section (2); the outer diameter of the different-diameter section (3) is greater than the outer diameter of the regular section (1), the minimum outer diameter of the diameter-changing section (2) is equal to the outer diameter of the regular section (1), and the maximum outer diameter of the diameter-changing section (2) is equal to the outer diameter of the different-diameter section (3); heat dissipation fins (300) are provided on the different-diameter section (3); the outer diameter of the diameter-changing section (2) gradually increases along the direction from the regular section (1) to the different-diameter section (3).

2. The heat-resistant alloy finned tube according to claim 1, characterized in that: The different-diameter section (3) includes a connection end (31) connected to the diameter-changing section (2), an intermediate section (32) provided with the heat dissipation fins (300), and a tail end (33) connecting the intermediate section (32).

3. A heat-resistant alloy finned tube according to claim 2, characterized in that: The wall thickness of the intermediate section (32) is 0.8 to 1.2 times the wall thickness of the regular section (1).

4. A heat-resistant alloy finned tube according to claim 2, characterized in that: The wall thickness of the connection end (31) is equal to the wall thickness of the tail end (33); the sum of the wall thickness of the intermediate section (32) and the height of the heat dissipation fins (300) is not less than the wall thickness of the connection end (31).

5. The heat-resistant alloy finned tube according to claim 2, wherein: The heat dissipation fins (300) are spiral strips spirally arranged on the intermediate section (32) and are integrally connected to the intermediate section (32).

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