Preparation method of aluminum / stainless steel heat exchange tube for hot blast furnace

Abstract

The invention discloses a preparation method for an aluminum / stainless steel heat exchange tube for a hot blast furnace, comprising the following steps: (1) hot extrusion of an inner tube: hot extrusion of a hot aluminum ingot at a temperature of 420-500°C to produce an aluminum tube with plastic deformation, and the temperature of the aluminum tube being molded is 440-520°C; (2) heating of an outer tube: a stainless steel tube heated to 700-850°C is provided near the die outlet end of the extruded aluminum tube; (3) assembly: the aluminum tube with plastic deformation produced by extrusion is nested in the hot stainless steel tube of the outer layer during movement; (4) cooling: cooling the nested composite aluminum tube and stainless steel tube to obtain an aluminum stainless steel heat exchange tube. The invention is used for the preparation method of an aluminum / stainless steel heat exchange tube for a hot blast furnace, and the aluminum ingot and the stainless steel tube can be formed in one time, and the process is simple. The aluminum / stainless steel composite tube has high thermal conductivity, good high temperature resistance and tight interface bonding, and is used for the heat exchange tube of the hot blast furnace, which significantly improves the thermal conductivity and life of the heat exchange tube and improves the working performance of the hot blast furnace.

Description

Technical Field

[0001] The invention relates to the technical field of heat exchange tubes, and in particular to a method for preparing aluminum / stainless steel heat exchange tubes for hot blast furnaces. Background Art

[0002] Hot air furnace is a device that uses the heat generated by fuel combustion to exchange heat with air to produce hot air. It is widely used in heating and drying of grain, cash crops, food, wood, pharmaceuticals, metallurgy, textiles, etc. The development of high-efficiency and energy-saving hot air furnaces is an important topic in the drying industry. There are many types of hot air furnaces and a full range of series. They have been widely used and have become a substitute for electric heat sources and traditional steam heat sources in many industries. According to the transportation form, hot air furnaces can be divided into indirect gas hot air furnaces and direct gas hot air furnaces. Shell and tube hot air furnaces are a more commonly used structural form in indirect heating hot air furnaces. The heat exchanger is composed of heat exchange tubes arranged in a certain order. Flue gas and air flow outside and inside the tubes to realize the shell and tube heat exchange between flue gas and air. The heat exchange system is the most important part of the hot air furnace. The heat exchanger is the core of the hot air furnace heat exchange system. It is a device that realizes heat exchange between two fluids of different temperatures (cold and hot fluids). The thermal efficiency of the hot air furnace mainly depends on the structure and material properties of the heat exchanger.

[0003] According to market research, it can be found that most heat exchangers of hot blast furnaces are made of carbon steel, stainless steel, aluminum, copper, aluminum alloy, ceramics, etc. Under the same heat exchanger structure, the heat exchange efficiency mainly depends on the thermal conductivity coefficient of the material. The higher the thermal conductivity coefficient of the heat exchange tube, the higher the heat exchange efficiency and the higher the thermal efficiency of the hot blast furnace. In addition to thermal conductivity, the high temperature strength, oxidation resistance, life and cost of the material should also be considered in practical applications. The thermal conductivity of carbon steel is only 66w / (m·K), the heat exchange efficiency of carbon steel pipe is low, and the oxidation resistance of carbon steel is poor, and the service life is short. Stainless steel has good high temperature oxidation resistance and strength, but the high temperature thermal conductivity coefficient is only 20~30w / (m·K) on average, and the heat exchange rate of a single stainless steel pipe is low. Although pure aluminum has a high thermal conductivity coefficient (237w / m·K), it has a low melting point, low high temperature strength, and is easy to soften at high temperature. It can only be used in the split structure of tubular hot blast furnaces, resulting in low thermal efficiency of hot blast furnaces (less than 70%). Although pure copper has a high thermal conductivity coefficient, copper has poor oxidation resistance, a short service life, and is expensive, making it impossible to use on a large scale. Aluminum alloys have similar advantages and disadvantages to pure aluminum. Although ceramic materials have excellent high temperature resistance and are low in price, their thermal conductivity coefficient is not high (20-40w / (m·K), resulting in poor heat exchange efficiency of the heat exchanger and unable to meet the requirements of high-efficiency and energy-saving hot blast furnaces. In summary, the materials currently used for heat exchange tubes in hot blast furnaces have many problems and cannot simultaneously meet the requirements of high thermal conductivity, high heat exchange efficiency, high temperature and high strength, low cost, and long life.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing aluminum / stainless steel heat exchange tubes for hot blast furnaces, so as to prepare aluminum / stainless steel heat exchange tubes, thereby overcoming the contradiction that the thermal conductivity and heat resistance of existing heat exchange tubes cannot be achieved at the same time, as well as the disadvantage of loose composite interface bonding.

[0006] To achieve the above object, the present invention provides a method for preparing an aluminum / stainless steel heat exchange tube for a hot blast furnace, comprising the following steps:

[0007] (1) Inner tube hot extrusion: hot extrusion of hot aluminum ingots at a temperature of 420-500°C to produce plastically deformed aluminum tubes, and the temperature of the aluminum tubes out of the mold is 440-520°C;

[0008] (2) External tube heating: A stainless steel tube heated to 700-850°C is provided near the die outlet of the extruded aluminum tube;

[0009] (3) Assembly: The aluminum tube that is plastically deformed by extrusion is nested in the outer hot stainless steel tube during the moving and elongating process;

[0010] (4) Cooling: Cooling the nested composite aluminum / stainless steel composite tube to obtain an aluminum stainless steel heat exchange tube.

[0011] Preferably, in the above technical solution, the aluminum tube and the stainless steel tube are interference fit.

[0012] Preferably, in the above technical solution, the outer diameter of the aluminum tube during hot extrusion is 0.2-0.5 mm larger than the inner diameter of the stainless steel tube after heating.

[0013] Preferably, in the above technical solution, the inlet end where the stainless steel tube and the aluminum tube are nested is trumpet-shaped.

[0014] Preferably, in the above technical solution, the inner diameter of the trumpet-shaped inlet end of the stainless steel tube is larger than the outer diameter of the hot aluminum tube when extruded, and the inclination angle of the trumpet-shaped inlet end of the stainless steel tube is 1-5°.

[0015] Preferably, in the above technical solution, the length of the trumpet-shaped inlet end of the stainless steel tube is 0.5-3 cm.

[0016] Preferably, in the above technical solution, the speed at which the aluminum tube moves and is nested in the outer stainless steel tube is 5-15 m / min.

[0017] Preferably, in the above technical solution, the stainless steel pipe includes one of 304, 309, 310 or 316 stainless steel.

[0018] Preferably, in the above technical solution, before the stainless steel pipe is heated and assembled, the inner wall of the stainless steel pipe is mechanically polished with a cylindrical wire brush to expose a clean and fresh metal surface of the inner wall.

[0019] Preferably, in the above technical solution, after the hot aluminum tube and the hot stainless steel tube are assembled in step (3), they are kept at a temperature of 600-850°C for 10-15 minutes and then cooled by air cooling. After the aluminum tube is squeezed into the stainless steel tube, it is kept at a temperature of 10-15 minutes to promote temperature balance, so that the atoms at the interface of the two tubes are fully diffused and bonded, and the interface bonding is dense and firm.

[0020] An aluminum / stainless steel heat exchange tube for a hot blast furnace is made using the above method. The aluminum / stainless steel heat exchange tube for a hot blast furnace comprises an aluminum inner tube and a stainless steel outer tube from the inside to the outside.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention is used for the preparation method of aluminum / stainless steel heat exchange tubes for hot blast furnaces. After hot aluminum ingots are extruded into hot aluminum tubes, they are immediately compounded with hot stainless steel tubes (below the anti-oxidation temperature). The surface of the aluminum tube does not have time to form an oxide film, and the interface bonding effect with the stainless steel is good. At the same time, the inner tube and the outer tube are both hot during compounding, which is conducive to the diffusion of interface atoms and also conducive to improving the interface bonding effect. There is no need to specifically remove the oxide film from the aluminum tube before compounding, which saves process and cost.

[0023] (2) The preparation method of the present invention is that the stainless steel tube and the aluminum tube have the characteristics of thermal expansion and contraction (the thermal expansion coefficient of aluminum is 23.2×10 -6 / K, the thermal expansion coefficient of stainless steel is 15×10 -6 ), after cooling, the stainless steel will shrink, thus stabilizing the aluminum tube bridge sleeve and creating an interference fit. Control the heating temperature of the stainless steel outer tube so that the shrinkage of the stainless steel outer tube after cooling is greater than that of the aluminum inner tube.

[0024] (3) The aluminum / stainless steel tube produced by the method of the present invention has high thermal conductivity, good high temperature resistance, oxidation resistance and tight interface bonding, and is used for heat exchange tubes of hot blast stoves to improve the heat exchange rate of hot blast stoves. It can significantly improve the thermal conductivity and heat exchange efficiency of the heat exchange tube, improve the working performance of the hot blast stove, and promote energy saving.

[0025] (4) The aluminum / stainless steel tube of the present invention is used as a heat exchange tube for a hot blast furnace. When the combustion temperature is high, the aluminum inner tube expands due to the heat, and the stainless steel outer tube has high high-temperature strength, so the shape of the heat exchange tube is not easily deformed. At the same time, due to the large expansion coefficient of the aluminum tube, the interface between the aluminum tube and the stainless steel tube is more tightly combined, which can greatly improve the external-inside heat conduction rate and improve the heat exchange rate of the hot blast furnace. Due to the high temperature resistance and oxidation resistance of stainless steel, the service life of the heat exchange tube is greatly extended. At the same time, the working performance of the hot blast furnace is improved, and energy conservation and emission reduction are promoted.

[0026] (5) The aluminum / stainless steel composite pipe of the present invention combines the advantages of stainless steel in high strength, oxidation resistance and long life with the advantages of aluminum in high thermal conductivity, oxidation resistance and low cost. The aluminum ingot and the stainless steel pipe are prepared into a composite pipe through a simple extrusion process. The composite pipe simultaneously achieves the purposes of high thermal conductivity, high strength, oxidation resistance, low cost and long life, which is of great significance to improving the thermal efficiency of the hot blast furnace and promoting energy conservation and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the assembly of aluminum / stainless steel heat exchange tubes for hot blast furnaces according to the present invention.

[0028] Description of main reference numerals:

[0029] 1-Aluminum inner tube, 2-Stainless steel outer tube. DETAILED DESCRIPTION

[0030] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0031] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0032] As shown in the figure, the aluminum / stainless steel heat exchange tube for hot blast furnace according to the specific embodiment of the present invention includes an aluminum inner tube 1 and a stainless steel outer tube 2 from the inside to the outside. The specific preparation method includes the following steps:

[0033] (1) Inner tube hot extrusion:

[0034] First, the hot aluminum ingot is extruded by moving the core. When the core moves to the other end of the mold, the slider immediately moves horizontally to extrude the aluminum ingot. The extruded aluminum ingot is an aluminum tube that is plastically deformed by hot extrusion of the hot aluminum ingot at a temperature of 420-500℃. The temperature of the aluminum tube out of the mold is 440-520℃.

[0035] (2) External tube heating

[0036] Near the die outlet of the extruded aluminum tube, a stainless steel tube heated to 700-850°C is detachably fixed, and the heating temperature is below the anti-oxidation temperature of stainless steel. The stainless steel tube is made of 304, 309, 310, and 316 stainless steel. Before the stainless steel tube is heated and assembled, the inner wall of the stainless steel tube is mechanically polished with a wire brush to expose a clean and fresh surface.

[0037] (3) Assembly

[0038] The aluminum tube that is plastically deformed by extrusion is nested in the outer stainless steel tube during movement. The speed of the aluminum tube in the movement of the outer stainless steel tube is 5-15 m / min, wherein the aluminum tube and the stainless steel tube are interference fit. Preferably, the outer diameter of the hot aluminum tube is 0.2-0.5 mm larger than the inner diameter of the heated stainless steel tube.

[0039] The outer diameter of the aluminum tube has an interference fit with the stainless steel tube. During the nesting and assembly process of the hot aluminum tube and the heated stainless steel tube, the outer surface of the aluminum tube and the inner surface of the stainless steel tube rub against each other, which is beneficial to the diffusion of interface atoms and also beneficial to improving the interface bonding effect, thereby improving the bonding effect between the aluminum tube and the stainless steel tube.

[0040] The inlet end of the stainless steel tube and the aluminum tube is in a trumpet shape. The inner diameter of the trumpet-shaped inlet end of the stainless steel tube is larger than the outer diameter of the aluminum tube, and the inclination angle of the trumpet-shaped inlet end of the stainless steel tube is 1-5 degrees. The length of the trumpet-shaped inlet end of the stainless steel tube is 0.5-3cm. The trumpet-shaped inlet end of the stainless steel tube allows the aluminum tube to enter the stainless steel tube smoothly and quickly, thereby achieving rapid assembly. At the same time, the wall thickness and shape of the aluminum tube are maintained to prevent deformation of the aluminum tube.

[0041] (4) Cooling: After the hot aluminum tube and the hot stainless steel tube are assembled, they are kept at a temperature of 600-850°C for 10-15 minutes and then cooled by air cooling to obtain an aluminum / stainless steel heat exchange tube.

[0042] The present invention uses hot aluminum ingots to extrude hot aluminum tubes and then immediately composite them with hot stainless steel tubes. The aluminum tube surface does not have time to form an oxide film, and the interface bonding effect with the stainless steel is good. At the same time, the inner tube and the outer tube are both hot during the composite process, which is conducive to the diffusion of interface atoms and also helps to improve the interface bonding effect. Before composite, there is no need to specifically remove the oxide film from the aluminum tube, which saves process and cost. Since stainless steel tubes and aluminum tubes have the characteristics of thermal expansion and contraction (the thermal expansion coefficient of aluminum is 23.2×10 -6 / K, the thermal expansion coefficient of stainless steel is 15×10 -6 / K), after the stainless steel is heated to 700-850℃, the shrinkage of the stainless steel after cooling is greater than the shrinkage of the aluminum inner tube, thereby firmly fixing the aluminum tube sleeve and producing an interference fit.

[0043] Further explanation is given in conjunction with specific embodiments

[0044] Example 1

[0045] Aluminum / stainless steel heat exchange tubes for hot blast furnaces are produced using 304 stainless steel and pure aluminum ingots. The heat exchange tubes include an aluminum inner tube 1 and a stainless steel outer tube 2 from the inside to the outside. The specific preparation method includes the following steps:

[0046] (1) Inner tube hot extrusion:

[0047] First, the hot aluminum ingot is extruded by moving the core. When the core moves to the other end of the mold, the slider immediately moves horizontally to extrude the aluminum ingot. The extruded pure aluminum ingot is an aluminum tube that is plastically deformed by hot extrusion of the hot aluminum ingot at a temperature of 420-440℃. The temperature of the aluminum tube out of the mold is 440-460℃.

[0048] (2) External tube heating

[0049] Near the die outlet of the extruded aluminum tube, a stainless steel tube heated to 700-720°C is detachably fixed. Before the stainless steel tube is heated and assembled, the inner wall of the stainless steel tube is mechanically polished with a wire brush to expose fresh and clean metal on the inner surface.

[0050] (3) Assembly

[0051] The aluminum tube that is plastically deformed by extrusion is nested in the outer stainless steel tube during movement. The speed of the aluminum tube in the movement and nesting in the outer stainless steel tube is 15m / min, wherein the aluminum tube and the stainless steel tube are interference fit. Preferably, the outer diameter of the hot aluminum tube is 0.2-0.3mm larger than the inner diameter of the heated stainless steel tube. The inlet end where the stainless steel tube and the aluminum tube are nested is trumpet-shaped. The inner diameter of the trumpet-shaped inlet end of the stainless steel tube is larger than the outer diameter of the aluminum tube, and the inclination angle of the trumpet-shaped inlet end of the stainless steel tube is 2-3°. The length of the trumpet-shaped inlet end of the stainless steel tube is 3cm.

[0052] (4) Cooling: After the hot aluminum tube and the hot stainless steel tube are assembled, they are kept at a temperature of 650-700°C for 10-15 minutes and then cooled by air cooling to obtain an aluminum / stainless steel heat exchange tube.

[0053] Example 2

[0054] Aluminum / stainless steel heat exchange tubes for hot blast furnaces are produced using 309 stainless steel and pure aluminum ingots. The heat exchange tubes include an aluminum inner tube 1 and a stainless steel outer tube 2 from the inside to the outside. The specific preparation method includes the following steps:

[0055] (1) Inner tube hot extrusion:

[0056] First, the hot aluminum ingot is extruded by moving the core. When the core moves to the other end of the mold, the slider immediately moves horizontally to extrude the aluminum ingot. The extruded pure aluminum ingot is an aluminum tube that is plastically deformed by hot extrusion of the hot aluminum ingot at a temperature of 440-450℃. The temperature of the aluminum tube out of the mold is 460-470℃.

[0057] (2) External tube heating

[0058] Near the die outlet of the extruded aluminum tube, a stainless steel tube heated to 760-780°C is detachably fixed. Before the stainless steel tube is heated and assembled, the inner wall of the stainless steel tube is mechanically polished with a wire brush to expose fresh metal on the inner surface.

[0059] (3) Assembly

[0060] The aluminum tube that is plastically deformed by extrusion is nested in the outer stainless steel tube during movement. The speed of the aluminum tube in the movement and nesting in the outer stainless steel tube is 12m / min. The aluminum tube and the stainless steel tube are interference fit. Preferably, the outer diameter of the hot aluminum tube is 0.2-0.3mm larger than the inner diameter of the heated stainless steel tube. The inlet end where the stainless steel tube and the aluminum tube are nested is trumpet-shaped. The inner diameter of the trumpet-shaped inlet end of the stainless steel tube is larger than the outer diameter of the aluminum tube, and the inclination angle of the trumpet-shaped inlet end of the stainless steel tube is 2-3°. The length of the trumpet-shaped inlet end of the stainless steel tube is 3cm.

[0061] (4) Cooling: After the hot aluminum tube and the hot stainless steel tube are assembled, they are kept at a temperature of 700-800°C for 10-15 minutes and then cooled by air cooling to obtain an aluminum / stainless steel heat exchange tube.

[0062] Example 3

[0063] Aluminum / stainless steel heat exchange tubes for hot blast furnaces are produced using 6061 aluminum alloy ingots and 310 stainless steel. The heat exchange tubes include an aluminum alloy inner tube 1 and a stainless steel outer tube 2 from the inside to the outside. The specific preparation method includes the following steps:

[0064] (1) Inner tube hot extrusion:

[0065] First, the hot aluminum ingot is extruded by moving the core. When the core moves to the other end of the mold, the slider immediately moves horizontally to extrude the aluminum ingot. The extruded aluminum alloy ingot is an aluminum tube that is plastically deformed by hot extrusion of the hot aluminum ingot at a temperature of 480-500℃. The temperature of the aluminum tube out of the mold is 490-510℃.

[0066] (2) External tube heating

[0067] Near the die outlet of the extruded aluminum tube, a stainless steel tube heated to 780-800°C is detachably fixed. Before the stainless steel tube is heated and assembled, the inner wall of the stainless steel tube is mechanically polished with a wire brush to expose fresh metal on the inner surface.

[0068] (3) Assembly

[0069] The aluminum tube that is plastically deformed by extrusion is nested in the outer stainless steel tube during movement. The speed at which the aluminum alloy tube is nested in the outer stainless steel tube is 6m / min. The aluminum tube and the stainless steel tube are interference fit. Preferably, the outer diameter of the hot aluminum tube is 0.2-0.3mm larger than the inner diameter of the stainless steel tube after heating. The inlet end where the stainless steel tube and the aluminum tube are nested is trumpet-shaped. The inner diameter of the trumpet-shaped inlet end of the stainless steel tube is larger than the outer diameter of the aluminum tube, and the inclination angle of the trumpet-shaped inlet end of the stainless steel tube is 2-3°. The length of the trumpet-shaped inlet end of the stainless steel tube is 3cm.

[0070] (4) Cooling: After the hot aluminum tube and the hot stainless steel tube are assembled, they are kept at a temperature of 700-800°C for 10-15 minutes and then cooled by air cooling to obtain an aluminum / stainless steel heat exchange tube.

[0071] Example 4

[0072] Aluminum / stainless steel heat exchange tubes for hot blast furnaces are produced using 316 stainless steel and 6061 aluminum alloy ingots. The heat exchange tubes include an aluminum inner tube 1 and a stainless steel outer tube 2 from the inside to the outside. The specific preparation method includes the following steps:

[0073] (1) Inner tube hot extrusion:

[0074] First, the hot aluminum ingot is extruded by moving the core. When the core moves to the other end of the mold, the slider immediately moves horizontally to extrude the aluminum ingot. The extruded aluminum ingot is an aluminum tube that is plastically deformed by hot extrusion of the hot aluminum ingot at a temperature of 480-500℃. The temperature of the aluminum tube out of the mold is 490-510℃.

[0075] (2) External tube heating

[0076] Near the die outlet of the extruded aluminum tube, a stainless steel tube heated to 820-840°C is detachably fixed. Before the stainless steel tube is heated and assembled, the inner wall of the stainless steel tube is mechanically polished with a wire brush to expose fresh metal on the inner surface.

[0077] (3) Assembly

[0078] The aluminum tube that is plastically deformed by extrusion is nested in the outer stainless steel tube during movement. The speed of the aluminum tube when it is nested in the outer stainless steel tube is 5-6m / min. The aluminum tube and the stainless steel tube are interference fit. Preferably, the outer diameter of the hot aluminum tube is 0.3-0.4mm larger than the inner diameter of the heated stainless steel tube. The inlet end where the stainless steel tube and the aluminum alloy tube are nested is trumpet-shaped. The inner diameter of the trumpet-shaped inlet end of the stainless steel tube is larger than the outer diameter of the aluminum tube, and the inclination angle of the trumpet-shaped inlet end of the stainless steel tube is 2-3°. The length of the trumpet-shaped inlet end of the stainless steel tube is 3cm.

[0079] (4) Cooling: After the hot aluminum tube and the hot stainless steel tube are assembled, they are kept at a temperature of 700-800°C for 10-15 minutes and then cooled by air cooling to obtain an aluminum / stainless steel heat exchange tube.

[0080] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for preparing aluminum / stainless steel heat exchange tubes for hot blast furnaces, characterized in that: The following steps are involved: (1) Inner tube hot extrusion: hot extrusion of hot aluminum ingots at a temperature of 420-500°C to produce plastically deformed aluminum tubes, and the temperature of the aluminum tubes out of the mold is 440-520°C; (2) External tube heating: A stainless steel tube heated to 700-850°C is provided near the die outlet of the extruded aluminum tube; (3) Assembly: The aluminum tube that is plastically deformed by extrusion is nested in the outer hot stainless steel tube during the moving and elongating process; (4) Cooling: Cooling the nested composite aluminum / stainless steel composite tube to obtain an aluminum / stainless steel heat exchange tube.

2. The method for preparing aluminum / stainless steel heat exchange tubes for hot blast furnaces according to claim 1, characterized in that: The aluminum tube and the stainless steel tube are interference fit.

3. The method for preparing aluminum / stainless steel heat exchange tubes for hot blast furnaces according to claim 2, characterized in that: The outer diameter of the aluminum tube during hot extrusion is 0.2-0.5 mm larger than the inner diameter of the heated stainless steel tube.

4. The method for preparing aluminum / stainless steel heat exchange tubes for hot blast furnaces according to claim 1, characterized in that: The inlet end where the stainless steel tube and the aluminum tube are nested is in a trumpet shape.

5. The method for preparing aluminum / stainless steel heat exchange tubes for hot blast furnaces according to claim 4, characterized in that: The inner diameter of the trumpet-shaped inlet end of the stainless steel tube is larger than the outer diameter of the hot aluminum tube when extruded, and the inclination angle of the trumpet-shaped inlet end of the stainless steel tube is 1-5°; the length of the trumpet-shaped inlet end of the stainless steel tube is 0.5-3cm.

6. The method for preparing aluminum / stainless steel heat exchange tubes for hot blast furnaces according to claim 1, characterized in that: The speed at which the aluminum tube moves and is nested in the outer stainless steel tube is 5-15m / min.

7. The method for preparing aluminum / stainless steel heat exchange tubes for hot blast furnaces according to claim 1, characterized in that: The stainless steel pipe comprises one of 304, 309, 310 or 316 stainless steel.

8. The method for preparing aluminum / stainless steel heat exchange tubes for hot blast furnaces according to claim 1, characterized in that: Before the stainless steel pipe is heated and assembled, the inner wall of the stainless steel pipe is mechanically polished with a wire brush to expose a clean and fresh metal surface of the inner wall.

9. The method for preparing aluminum / stainless steel heat exchange tubes for hot blast furnaces according to claim 1, characterized in that: Step (3) After the hot aluminum tube and the hot stainless steel tube are assembled, they are kept warm for 10-15 minutes at a temperature of 600-850° C. and then cooled by air cooling.

10. An aluminum / stainless steel heat exchange tube for a hot blast furnace, characterized in that: The hot blast furnace aluminum / stainless steel heat exchange tube is manufactured by the method according to any one of claims 1 to 9, and comprises an aluminum inner tube and a stainless steel outer tube from the inside to the outside.

Images