An argon-protected oxygen-free continuous solution furnace for stainless steel pipes and a heat treatment method

Abstract

The present invention discloses an argon-protected oxygen-free continuous solution furnace for stainless steel pipes and a heat treatment method, which includes a heat treatment furnace, an argon solution device, and a conveying mechanism; an argon main pipeline is provided on the outer sides of both the heat treatment furnace and the argon solution device, and a plurality of air inlets connecting the argon main pipeline are provided along the length direction of the heat treatment furnace; the argon solution device includes a furnace body, an upper argon spray cooling mechanism and a lower argon spray cooling mechanism are respectively arranged on the upper and lower sides of the conveying mechanism in the furnace body, and both the upper argon spray cooling mechanism and the lower argon spray cooling mechanism are connected to the argon main pipeline; the present invention uses argon as the protective gas for the solution of steel pipes, and at the same time uses high-pressure argon instead of water as the cooling medium for the solution of stainless steel pipes, realizing the continuous non-oxidizing solution treatment of stainless steel pipes and improving the surface quality and performance of stainless steel pipes.

Description

Technical Field

[0001] The present invention relates to the technical field of solution heat treatment for nuclear power stainless steel pipes, and particularly to an argon-protected oxygen-free continuous solution furnace for stainless steel pipes and a heat treatment method. Background Art

[0002] Solution treatment is a heat treatment process, specifically referring to heating an alloy to a constant temperature in a high-temperature single-phase region, maintaining it, fully dissolving the excess phase into the solid solution, and then rapidly cooling to obtain a supersaturated solid solution. By solution treatment, stainless steel can fix the high-temperature structure at room temperature to obtain austenite supersaturated with carbon, thereby improving the corrosion resistance of chromium-nickel stainless steel and also enhancing the plasticity and toughness of chromium-nickel stainless steel.

[0003] Currently, there are mainly two solution methods for nuclear power stainless steel pipes. One is to heat and hold a nuclear power stainless steel pipe in a heat treatment furnace without a protective atmosphere for a period of time and then put it into water for cooling and solution. Since there is no gas protection in this solution method, the surface of the stainless steel pipe will be oxidized to form black and yellow oxide scales, so pickling and passivation treatments are required in the subsequent process before delivery. The other is to put the stainless steel pipe into a protective atmosphere (full hydrogen atmosphere or ammonia decomposition atmosphere), heat and hold it for a period of time, and then put it into water for solution. Since the heating is carried out in a protective reducing atmosphere, the surface of the stainless steel pipe will not be oxidized, so pickling and passivation processes in the subsequent process are not required.

[0004] Due to the harsh use environment of nuclear power stainless steel pipes, high requirements are imposed on their anti-corrosion performance, mechanical properties, and physical and chemical properties. Nuclear power stainless steel pipes belong to high-end stainless steel products with high added value, so many special steel enterprises are vigorously developing them. However, there are certain defects in the above two solution processes at present.

[0005] For the first process, oxide scales will form on the surface of the steel pipe after heating, and pickling and passivation treatments are required. Stainless steel pickling and passivation not only increase the process cost but also the waste liquid generated will bring additional costs to the production enterprise in terms of waste liquid treatment and environmental protection. At the same time, pickling and passivation will also change the physical and chemical properties of the steel pipe, affecting its use in the reactor.

[0006] The second process uses a protective atmosphere of full hydrogen or ammonia decomposition. Although both atmospheres can heat the steel pipe in an oxygen-free environment, they themselves will also have a certain impact on the performance of the steel pipe. For a full hydrogen atmosphere, H2 will react with the surface components of the stainless steel pipe to reduce the strength, plasticity and toughness of the stainless steel pipe to a certain extent. These reactions make nuclear power stainless steel pipes prone to hydrogen embrittlement, the plasticity of the steel pipe will be reduced, and the tensile fracture will change from ductile fracture to brittle fracture; for ammonia decomposition atmosphere, there will sometimes be trace amounts of water and CO2 in the atmosphere, which will react with Cr in the steel pipe to generate Cr2O3, CO, CH4 and CrC, which can lead to chromium depletion between stainless steel crystals and reduce the corrosion resistance of nuclear power stainless steel pipes. And if the ammonia decomposition rate is too low, the remaining NH3 in the furnace will be pyrolyzed into atomic N, causing slight nitridation on the surface of the steel pipe, which is also detrimental to the performance of nuclear power stainless steel pipes. Summary of the invention

[0007] The purpose of the present invention is to provide an argon-protected oxygen-free continuous solid solution furnace and a heat treatment method for stainless steel pipes in view of the problems existing in the prior art. Argon is used as a protective gas for the solid solution of the steel pipe, and high-pressure argon is used instead of water as a cooling medium for the solid solution of the stainless steel pipe, so as to realize continuous oxidation-free solid solution treatment of the stainless steel pipe and improve the surface quality and performance of the stainless steel pipe.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] An argon-protected oxygen-free continuous solid solution furnace for stainless steel pipes comprises a heat treatment furnace, an argon solid solution device and a conveying mechanism, wherein the outlet of the heat treatment furnace is connected to the inlet of the argon solid solution device, and the conveying mechanism is continuously arranged and passes through the heat treatment furnace and the argon solid solution device in sequence; an argon main pipeline is arranged on the outer side of the heat treatment furnace and the argon solid solution device, and the heat treatment furnace is provided with a plurality of air inlets connected to the argon main pipeline along the length direction; the argon solid solution device comprises a furnace body, and an upper argon spray cooling mechanism and a lower argon spray cooling mechanism are respectively arranged on the upper and lower sides of the conveying mechanism in the furnace body, and the upper argon spray cooling mechanism and the lower argon spray cooling mechanism are both connected to the argon main pipeline.

[0010] The improvement and advantage of the above scheme is that argon is used as a protective gas when the steel pipe passes through a heat treatment furnace, and argon is used as a cooling medium for solid solution of the steel pipe when the steel pipe passes through an argon solid solution device after being heated, so that the surface quality of the produced steel pipe is better and has fewer defects. Compared with solid solution using water, the surface of the steel pipe is brighter.

[0011] In some embodiments, the furnace body includes a water-cooled wall, the water-cooled wall includes a cooling cavity surrounded by a double-layer plate body, several support pipes are welded between the double-layer plate bodies, and a circulating water inlet and a circulating water outlet are arranged outside the water-cooled wall; the cooling water at the circulating water outlet passes through a cooling tower and then flows into the cooling cavity through the circulating water inlet for internal circulation to absorb and carry away heat; a sewage through-hole penetrating up and down is arranged on the water-cooled wall at the bottom of the furnace body, and a cooling water sewage hole communicating with the cooling cavity is arranged outside the water-cooled wall at the bottom of the furnace body.

[0012] The water-cooled wall is used to quickly carry out the heat of the argon gas in the furnace body to achieve rapid solution.

[0013] Both the upper argon gas spraying and cooling mechanism and the lower argon gas spraying and cooling mechanism include spraying and cooling ports extending relative to the conveying direction of the conveying mechanism, and a plurality of spraying and cooling small holes are arranged on the side of the spraying and cooling port facing the conveying mechanism.

[0014] The argon gas is sprayed in an up-and-down opposite spraying manner, so that all surfaces of the steel pipe can uniformly contact the argon gas, and the argon gas stays for enough time to carry away heat; by arranging the spraying and cooling small holes, the argon gas can be uniformly dispersed.

[0015] In some embodiments, a three-way connecting pipe is fixedly arranged outside the top of the furnace body, and the three ports of the three-way connecting pipe are respectively connected to a circulating fan, an argon gas circulation pipeline and the inside of the furnace body. The other end of the argon gas circulation pipeline is divided into two branches and extends into the inside of the furnace body and is respectively connected to the upper argon gas spraying and cooling mechanism and the lower argon gas spraying and cooling mechanism. The argon gas circulation pipeline is also connected to an argon gas supplement pipe, and the argon gas supplement pipe is connected to the argon gas main pipeline through an electric butterfly valve; a shell-and-tube water-cooled heat exchanger is detachably arranged above the upper argon gas spraying and cooling mechanism inside the furnace body.

[0016] In the above solution, when the argon gas contacts the steel pipe and carries away the heat on the surface of the steel pipe, the circulating fan sucks air from the three-way connecting pipe, the inside of the three-way connecting pipe is in negative pressure, sucking the argon gas in the furnace body. The argon gas is cooled when passing through the shell-and-tube water-cooled heat exchanger and is transported to the argon gas circulation pipeline to be re-sprayed onto the surface of the steel pipe for heat absorption.

[0017] Furthermore, two symmetrical baffles are connected to the inner wall of the top of the furnace body. The lower ends of the two baffles are both connected to heat exchanger support guide rails. The shell-and-tube water-cooled heat exchanger is arranged between the two baffles and is slidably connected to the heat exchanger support guide rails. One end of the shell-and-tube water-cooled heat exchanger extends out of the side wall of the furnace body and is connected to a cover plate, and the cover plate is hermetically connected to the furnace body. By disassembling and assembling the shell-and-tube water-cooled heat exchanger in a similar way of drawer sliding, it is convenient for maintenance and replacement.

[0018] The outside of the heat treatment furnace is provided with a gas main pipe, an air main pipe and a flue gas main pipe. The two opposite side walls of the heat treatment furnace are provided with a plurality of heating units, which are arranged in an up-and-down staggered manner. The heating unit includes a burner penetrating the side wall of the heat treatment furnace and a gas branch pipe, an air branch pipe and a flue gas branch pipe connected to the burner. The gas branch pipe is connected to a proportional valve, and the air branch pipe is connected to an electric regulating valve and a manual butterfly valve in sequence. The gas branch pipe, the air branch pipe and the flue gas branch pipe of each heating unit are respectively connected to the gas main pipe, the air main pipe and the flue gas main pipe. The up-and-down staggered arrangement of the heating units can make the temperature in the furnace uniform. By installing the burner and the argon gas inlet on the same wall, the steel pipe is always heated under the protection of argon gas.

[0019] The inlet of the heat treatment furnace is connected to a loading device, the outlet of the argon solid solution device is connected to a water cooling box, and the water cooling box is connected to a unloading device; the conveying mechanism continuously passes through the loading device, the heat treatment furnace, the argon solid solution device, the water cooling box and the unloading device.

[0020] The loading device consists of a storage table and a feed roller table. The transmission mechanism drives the transmission roller to rotate through chains and gears. The steel pipe is first lifted onto the storage table, and the electro-hydraulic push rod works to lift the frame as a whole so that the upper surface of the frame is level with the upper surface of the storage table. After the worker pushes the steel pipe onto the feed roller table, the electro-hydraulic push rod works to lower the frame as a whole, and the steel pipe falls exactly on the rolling transmission roller and is transmitted to the heat treatment furnace.

[0021] The temperature of the steel pipe after argon solid solution is about 250-300℃. If it is taken out of the furnace directly at this time, the surface of the steel pipe will still oxidize and form a slight yellow oxide scale after encountering the air. Therefore, a water cooling box should be added after the argon solid solution section to speed up the cooling of the steel pipe. After passing through the water cooling box section, the temperature of the steel pipe will drop below 180℃. At this time, the steel pipe will not oxidize if it is taken out of the furnace.

[0022] The unloading device consists of a discharging roller table and a collection basket. The transmission mechanism drives the transmission roller to rotate through chains and gears. The steel pipe is driven out of the water cooling box to the storage roller table. The electro-hydraulic push rod works to lift the frame as a whole. The frame lifts the steel pipe and makes it move horizontally under the drive of the translation chain to reach the collection basket.

[0023] Further, temperature detection devices are installed at both the inlet and outlet positions of the argon solid solution device. The temperature detection device is preferably a thermocouple, which transmits the temperature data at both ends of the argon solid solution device to the controller. The controller automatically analyzes and monitors the cooling rate of the steel pipe. When the cooling rate of the steel pipe is lower than the set rate, first, the circulation fan will increase the frequency of the motor to increase the fan speed and improve the argon circulation volume. If the cooling rate still cannot reach the target value after the frequency of the circulation fan reaches the set maximum value, then the controller will increase the argon flow rate by adjusting the electric control butterfly valve on the argon supply pipe to increase the speed and volume of the argon sprayed from the spray cooling nozzles, so as to achieve the target cooling rate.

[0024] In the above solution, the controller can be selected as a Siemens 1200 series PLC programmable controller.

[0025] Further, furnace doors are provided at both the inlet and outlet ends of the heat treatment furnace and the argon solid solution device. Sealing curtains are hung on the top walls inside the furnace doors. The furnace doors can move up and down through motors to adjust the opening degree, thereby controlling the pressure inside the furnace. The sealing curtains are made of stainless steel sheets to prevent the exchange of internal and external gases and ensure an oxygen-free environment inside the furnace.

[0026] The present invention also provides a heat treatment method for an argon-protected oxygen-free continuous solid solution furnace for stainless steel pipes, including the following steps:

[0027] S1. The steel pipe is continuously fed into the heat treatment furnace along its length direction by a conveying mechanism, and different parts of the steel pipe are successively heated in the heat treatment furnace under the protection of argon.

[0028] S2. The heated part of the steel pipe is continuously fed into the argon solid solution device by the conveying mechanism. The upper argon spray cooling mechanism and the lower argon spray cooling mechanism simultaneously spray high-pressure argon onto the upper and lower surfaces of the steel pipe. The argon sprayed onto the steel pipe and heated is attracted by the circulation fan at the top and flows through the shell-and-tube water-cooled heat exchanger to be re-cooled. The cooled argon then passes through the argon circulation pipeline and is sprayed onto the steel pipe surface again through the upper argon spray cooling mechanism and the lower argon spray cooling mechanism to cool it down.

[0029] S3. The temperature detection devices at the inlet and outlet of the argon solid solution device transmit the temperature data at both ends to the controller. The controller automatically analyzes and monitors the cooling rate of the steel pipe. When the cooling rate of the steel pipe is lower than the set rate, first, the circulation fan will increase the frequency of the motor to increase the fan speed and improve the argon circulation volume.

[0030] If the cooling rate still cannot reach the target value after the frequency of the circulation fan reaches the set maximum value, then the controller will increase the argon flow rate by adjusting the electric butterfly valve on the argon supply pipe to increase the speed and flow rate of the argon sprayed from the upper argon spray cooling mechanism and the lower argon spray cooling mechanism, so as to achieve the target cooling rate.

[0031] The non-oxygen continuous solution furnace provided by the present invention can realize the non-oxidation continuous solution production of stainless steel pipes for nuclear power, greatly improving the solution efficiency and output of stainless steel.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. The present invention uses argon as the protective gas, which can prevent the formation of oxide scales on the surface of stainless steel pipes for nuclear power during heating, reducing the two subsequent processes of pickling and passivation, lowering the production cost and avoiding the influence of the processes on the physical and chemical properties of stainless steel pipes for nuclear power;

[0034] 2. The present invention uses argon as the protective gas and simultaneously uses high-pressure argon instead of water as the cooling medium for the solution of stainless steel pipes for nuclear power, avoiding the oxidation on the surface of stainless steel pipes for nuclear power caused by water solution; through this process change, the performance and surface quality of stainless steel pipes for nuclear power are greatly improved;

[0035] 3. The feeding device, heat treatment furnace, argon solution device, water cooling box and discharging device of the present invention are connected in sequence, designed as a continuous furnace, which can improve the output of stainless steel pipes for nuclear power;

[0036] 4. This furnace type can realize the non-oxidation continuous solution production of stainless steel pipes for nuclear power, greatly improving the solution efficiency and output of stainless steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a cross-sectional view of the argon solution device of the present invention;

[0038] Figure 2 It is a longitudinal sectional view of the argon solution device of the present invention;

[0039] Figure 3 It is a longitudinal sectional view of the heat treatment furnace of the present invention;

[0040] Figure 4 It is a partial enlarged view of the heating unit of the present invention;

[0041] In the figure: 1. Conveyor mechanism; 2. Furnace body; 3. Upper argon spray cooling mechanism; 4. Lower argon spray cooling mechanism; 5. Support pipe; 6. Sewage through hole; 7. Cooling water sewage hole; 8. Three-way connecting pipe; 9. Circulation fan; 10. Argon circulation pipeline; 11. Argon supplement pipe; 12. Shell-and-tube water cooler; 13. Baffle; 14. Heat exchanger support guide rail; 15. Circulating water inlet; 16. Circulating water outlet; 17. Gas main pipe; 18. Air main pipe; 19. Burner; 20. Gas branch pipe; 21. Air branch pipe; 22. Proportion valve; 23. Electric control valve; 24. Manual butterfly valve. DETAILED DESCRIPTION OF THE INVENTION

[0042] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts belong to the scope of protection of the present invention.

[0043] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "top", "bottom", "inner", "outer", "horizontal", "vertical", etc. are all based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0044] Reference Figures 1 to 4 , an argon-protected oxygen-free continuous solution furnace for stainless steel pipes, comprising a heat treatment furnace, an argon solution device and a conveying mechanism 1. The outlet of the heat treatment furnace is connected to the inlet of the argon solution device, and the conveying mechanism 1 is continuously arranged and sequentially passes through the heat treatment furnace and the argon solution device; argon main pipelines are provided on the outer sides of both the heat treatment furnace and the argon solution device, and a plurality of air inlet holes connecting the argon main pipelines are provided along the length direction of the heat treatment furnace; the argon solution device comprises a furnace body 2, and an upper argon spray cooling mechanism 3 and a lower argon spray cooling mechanism 4 are respectively arranged on the upper and lower sides of the conveying mechanism 1 in the furnace body 2, and both the upper argon spray cooling mechanism 3 and the lower argon spray cooling mechanism 4 are connected to the argon main pipeline.

[0045] The improvement points and advantages of the above solution are that when the steel pipe passes through the heat treatment furnace, argon is used as the protective gas, and when the steel pipe passes through the argon solution device after being heated, argon is used as the cooling medium for the solution of the steel pipe, so that the surface quality of the produced steel pipe is better and the defects are fewer. Compared with solution with water, the surface of the steel pipe is brighter.

[0046] Argon is selected as the protective gas and cooling medium for the solution of nuclear power stainless steel pipes because of its excellent properties. First of all, argon is an inert gas, which is very stable and will not react with any components in the nuclear power stainless steel pipe. As a protective gas, it can fully ensure that the nuclear power stainless steel pipe is not oxidized during heating. At the same time, it will not penetrate into the surface of the steel pipe like N2 to cause slight nitriding on the surface of the steel pipe, thus changing its properties. The dew point of pure argon can reach below -51°C, which is an excellent protective gas.

[0047] In some embodiments, the furnace body 2 includes a water-cooled wall, which includes a cooling cavity surrounded by a double-layer plate body. A number of support pipes 5 are welded between the double-layer plate bodies. A circulating water inlet 15 and a circulating water outlet 16 are provided outside the water-cooled wall. The cooling water at the circulating water outlet 16 flows into the cooling cavity through the cooling tower and then circulates through the circulating water inlet 15 to absorb and carry away heat. A blowdown through-hole 6 that penetrates up and down is provided in the water-cooled wall at the bottom of the furnace body 2, and a cooling water blowdown hole 7 communicating with the cooling cavity is provided outside the water-cooled wall at the bottom of the furnace body 2.

[0048] The water-cooled wall is used to quickly carry out the heat of the argon gas in the furnace body 2 to achieve rapid solution treatment.

[0049] Both the upper argon gas spray cooling mechanism 3 and the lower argon gas spray cooling mechanism 4 include spray cooling ports extending in the conveying direction of the conveying mechanism 1. A number of spray cooling small holes are provided on the side of the spray cooling port facing the conveying mechanism 1.

[0050] The argon gas is sprayed in an up-and-down opposite spraying manner, so that all surfaces of the steel pipe can uniformly contact the argon gas, and the argon gas stays for a sufficient time to carry away heat. By providing the spray cooling small holes, the argon gas can be evenly dispersed.

[0051] In some embodiments, a three-way connecting pipe 8 is fixedly provided outside the top of the furnace body 2. The three ports of the three-way connecting pipe 8 are respectively connected to a circulating fan 9, an argon gas circulating pipeline 10, and the top wall of the furnace body 2. The other end of the argon gas circulating pipeline 10 is divided into two branches and extends into the interior of the furnace body 2 and is respectively connected to the upper argon gas spray cooling mechanism 3 and the lower argon gas spray cooling mechanism 4. The argon gas circulating pipeline 10 is also connected to an argon gas supplement pipe 11. The argon gas supplement pipe 11 is connected to the argon gas main pipeline through an electric butterfly valve. A shell-and-tube water-cooled heat exchanger 12 is detachably provided above the upper argon gas spray cooling mechanism 3 inside the furnace body 2.

[0052] In the above solution, when the argon gas contacts the steel pipe and carries away the heat on the surface of the steel pipe, the circulating fan 9 pumps air from the three-way connecting pipe 8. The inside of the three-way connecting pipe 8 is in negative pressure, sucking the argon gas in the furnace body 2. The argon gas is cooled when passing through the shell-and-tube water-cooled heat exchanger 12 and is transported to the argon gas circulating pipeline 10 and re-sprayed onto the surface of the steel pipe for heat absorption.

[0053] Furthermore, two symmetrical baffles 13 are connected to the top inner wall of the furnace body 2, and the lower ends of the two baffles 13 are connected to the heat exchanger support rails 14. The shell-and-tube water-cooled heat exchanger 12 is arranged between the two baffles 13 and is slidably connected to the heat exchanger support rails 14. One end of the shell-and-tube water-cooled heat exchanger 12 extends out of the side wall of the furnace body 2 and is connected to the cover plate, and the cover plate is sealed and connected to the furnace body 2. The shell-and-tube water-cooled heat exchanger 12 is disassembled and assembled in a manner similar to a drawer sliding, which is convenient for maintenance and replacement.

[0054] The outside of the heat treatment furnace is provided with a gas main pipe 17, an air main pipe 18 and a flue gas main pipe. The two opposite outer side walls of the heat treatment furnace are provided with a plurality of heating units, which are arranged in an up-and-down staggered manner. The heating unit includes a burner 19 penetrating the side wall of the heat treatment furnace and a gas branch pipe 20, an air branch pipe 21 and a flue gas branch pipe connected to the burner 19. The gas branch pipe 20 is connected to a proportional valve 22, and the air branch pipe 21 is connected to an electric regulating valve 23 and a manual butterfly valve 24 in sequence. The gas branch pipe 20, the air branch pipe 21 and the flue gas branch pipe of each heating unit are respectively connected to the gas main pipe 17, the air main pipe 18 and the flue gas main pipe. The up-and-down staggered arrangement of the heating units can make the temperature in the furnace uniform. By installing the burner 19 and the argon gas inlet on the same wall, the steel pipe is always heated under the protection of argon gas.

[0055] The inlet of the heat treatment furnace is connected to a loading device, the outlet of the argon solid solution device is connected to a water cooling box, and the water cooling box is connected to a unloading device; the conveying mechanism 1 passes through the loading device, the heat treatment furnace, the argon solid solution device, the water cooling box and the unloading device in sequence and continuously.

[0056] The loading device consists of a storage table and a feed roller table. The transmission mechanism 1 drives the transmission roller to rotate through chains and gears. The steel pipe is first lifted onto the storage table, and the electro-hydraulic push rod works to lift the frame as a whole so that the upper surface of the frame is flush with the upper surface of the storage table. After the worker pushes the steel pipe onto the feed roller table, the electro-hydraulic push rod works to lower the frame as a whole, and the steel pipe falls on the rolling transmission roller and is conveyed to the heat treatment furnace.

[0057] The temperature of the steel pipe after argon solid solution is about 250-300℃. If it is taken out of the furnace directly at this time, the surface of the steel pipe will still oxidize and form a slight yellow oxide scale after encountering the air. Therefore, a water cooling box should be added after the argon solid solution section to speed up the cooling of the steel pipe. After passing through the water cooling box section, the temperature of the steel pipe will drop below 180℃. At this time, the steel pipe will not oxidize if it is taken out of the furnace.

[0058] The blanking device consists of a discharge roller table and an aggregate basket. The transmission mechanism 1 drives the driving roller rod to rotate through a chain and a gear. The steel pipe is transmitted out of the water-cooling box and reaches the storage roller table. The electro-hydraulic push rod works to lift the overall frame, and the frame lifts the steel pipe and makes the steel pipe move horizontally under the drive of the translation chain to reach the aggregate basket.

[0059] Furthermore, temperature detection devices are installed at both the inlet and outlet positions of the argon solution device. The temperature detection device is preferably a thermocouple for temperature measurement. The thermocouple transmits the temperature data at both ends of the argon solution device to the controller. The controller automatically analyzes and monitors the cooling rate of the steel pipe. When the cooling rate of the steel pipe is lower than the set speed, first, the circulation fan 9 will increase the frequency of the motor to increase the fan speed and improve the circulation volume of argon. If the cooling rate still cannot reach the target value after the frequency of the circulation fan 9 reaches the set maximum value, then the controller will increase the flow rate of argon by adjusting the electric regulating butterfly valve on the argon supply pipe 11 to increase the speed and volume of the argon sprayed from the spray cooling port to achieve the target cooling rate.

[0060] In the above solution, the controller can be selected as a Siemens 1200 series PLC programmable controller.

[0061] Furthermore, furnace doors 25 are provided at both the inlet and outlet ends of the heat treatment furnace and the argon solution device. Sealing curtains 26 are hung on the top walls inside the furnace doors 25. The furnace doors 25 can move up and down through a motor to adjust the opening degree, thereby controlling the pressure inside the furnace. The sealing curtains 26 are made of stainless steel sheets to prevent the exchange of internal and external gases and ensure an oxygen-free environment inside the furnace.

[0062] The present invention also provides a heat treatment method for an argon-protected oxygen-free continuous solution furnace for stainless steel pipes, including the following steps:

[0063] S1. The steel pipe is continuously fed into the heat treatment furnace along its length direction by the transmission mechanism 1, and different parts of the steel pipe are heated successively in the heat treatment furnace under the protection of argon.

[0064] S2. The heated part of the steel pipe is continuously fed into the argon solution device by the transmission mechanism 1. The upper argon spray cooling mechanism 3 and the lower argon spray cooling mechanism 4 spray high-pressure argon onto the upper and lower surfaces of the steel pipe simultaneously. The argon sprayed onto the steel pipe and heated is attracted by the circulation fan 9 at the top and flows through the shell-and-tube water-cooled heat exchanger 12 to be cooled again. The cooled argon then passes through the argon circulation pipeline 10 and is sprayed onto the steel pipe surface again through the upper argon spray cooling mechanism 3 and the lower argon spray cooling mechanism 4 to cool it down.

[0065] S3. The temperature detection devices at the inlet and outlet of the argon solution device transmit the temperature data at both ends to the controller. The controller automatically analyzes and monitors the cooling rate of the steel pipe. When the cooling rate of the steel pipe is lower than the set speed, first, the circulation fan 9 will increase the frequency of the motor to increase the fan speed and improve the circulation volume of argon.

[0066] If the frequency of the circulation fan 9 reaches the set maximum value but still cannot make the cooling rate reach the target value, then the controller will increase the flow rate of argon by adjusting the electric butterfly valve on the argon supply pipe 11 to increase the spraying speed and flow rate of argon from the upper argon spray cooling mechanism 3 and the lower argon spray cooling mechanism 4, so as to achieve the target cooling rate.

[0067] The non-oxidizing continuous solution furnace provided by the present invention can realize the non-oxidizing continuous solution production of stainless steel pipes for nuclear power, greatly improving the solution efficiency and output of stainless steel.

[0068] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An argon - protected anaerobic continuous solution furnace for stainless steel pipes, characterized in that, It includes a heat treatment furnace, an argon solutionizing device, and a conveying mechanism (1). The outlet of the heat treatment furnace is connected to the inlet of the argon solutionizing device. The conveying mechanism (1) is continuously arranged and sequentially passes through the heat treatment furnace and the argon solutionizing device. Argon main pipelines are provided on the outer sides of both the heat treatment furnace and the argon solutionizing device. A number of air inlet holes connecting the argon main pipeline are provided along the length direction of the heat treatment furnace. The argon solutionizing device includes a furnace body (2) and an argon spray cooling mechanism provided inside the furnace body (2). The argon spray cooling mechanism is connected to the argon main pipeline. The argon spray cooling mechanism includes an upper argon spray cooling mechanism (3) and a lower argon spray cooling mechanism (4). The upper argon spray cooling mechanism (3) and the lower argon spray cooling mechanism (4) are respectively located on the upper and lower sides of the conveying mechanism (1). Both the upper argon spray cooling mechanism (3) and the lower argon spray cooling mechanism (4) are connected to the argon main pipeline. Both the upper argon spray cooling mechanism (3) and the lower argon spray cooling mechanism (4) include spray cooling ports extending along the conveying direction of the conveying mechanism (1). A number of spray cooling small holes are provided on the side of the spray cooling port facing the conveying mechanism (1). A three-way connecting pipe (8) is fixedly provided on the outer side of the top of the furnace body (2). The three ports of the three-way connecting pipe (8) are respectively connected to a circulation fan (9), an argon circulation pipeline (10), and the top wall of the furnace body (2). The other end of the argon circulation pipeline (10) is divided into two branches and extends into the interior of the furnace body and is respectively connected to the upper argon spray cooling mechanism (3) and the lower argon spray cooling mechanism (4). The argon circulation pipeline (10) is also connected to an argon supplement pipe (11). The argon supplement pipe (11) is connected to the argon main pipeline through an electric butterfly valve. A shell-and-tube water-cooled heat exchanger (12) is detachably provided above the upper argon spray cooling mechanism (3) inside the furnace body (2).

2. The argon - protected anaerobic continuous solution furnace for stainless steel pipes according to claim 1, characterized in that, Two symmetric baffles (13) are connected to the inner wall of the top of the furnace body (2). The lower ends of both the two baffles (13) are connected to heat exchanger support guide rails (14). The shell-and-tube water-cooled heat exchanger (12) is provided between the two baffles (13) and is slidably connected to the heat exchanger support guide rails (14). One end of the shell-and-tube water-cooled heat exchanger (12) extends out of the side wall of the furnace body (2) and is connected to a cover plate. The cover plate is hermetically connected to the furnace body.

3. The argon - protected anaerobic continuous solution furnace for stainless steel pipes according to claim 1, characterized in that, The furnace body (2) includes a water-cooled wall. The water-cooled wall includes a cooling cavity surrounded by a double-layer plate body. A number of support pipes (5) are welded between the double-layer plate bodies. A circulating water inlet (15) and a circulating water outlet (16) are provided on the outer side of the water-cooled wall. A sewage through hole (6) penetrating up and down is provided on the water-cooled wall at the bottom of the furnace body (2). A cooling water sewage hole (7) communicating with the cooling cavity is provided on the outer side of the bottom water-cooled wall of the furnace body (2).

4. The argon - protected anaerobic continuous solution furnace for stainless steel pipes according to claim 1, characterized in that, A gas main pipe (17), an air main pipe (18) and a flue gas main pipe are provided on the outer side of the heat treatment furnace. A plurality of heating units are provided on two opposite outer side walls of the heat treatment furnace, and the plurality of heating units are arranged in a vertically staggered manner; each heating unit includes a burner (19) penetrating through the side wall of the heat treatment furnace, and a gas branch pipe (20), an air branch pipe (21) and a flue gas branch pipe connected to the burner (19). The gas branch pipe (20) is connected with a proportional valve (22), and the air branch pipe (21) is sequentially connected with an electric control valve (23) and a manual butterfly valve (24); the gas branch pipe (20), the air branch pipe (21) and the flue gas branch pipe of each heating unit are respectively connected in a centralized manner to the gas main pipe (17), the air main pipe (18) and the flue gas main pipe.

5. The argon - protected anaerobic continuous solution furnace for stainless steel pipes according to claim 1, characterized in that, The inlet of the heat treatment furnace is connected to a loading device, the outlet of the argon solution heat treatment device is connected to a water cooling box, and the water cooling box is connected to an unloading device; the conveying mechanism sequentially and continuously passes through the loading device, the heat treatment furnace, the argon solution heat treatment device, the water cooling box and the unloading device.

6. The argon - protected anaerobic continuous solution furnace for stainless steel pipes according to claim 1, characterized in that, Temperature detection devices are installed at both the inlet and outlet positions of the argon solution heat treatment device.

7. A heat treatment method for the argon - protected anaerobic continuous solution furnace for stainless steel pipes according to any one of claims 1 to 6, characterized in that, It includes the following steps: S1. The steel pipe is continuously fed into the heat treatment furnace along the length direction by the conveying mechanism (1), and different parts of the steel pipe are heated in the heat treatment furnace successively under the protection of argon. S2. The heated part of the steel pipe is continuously fed into the argon solution heat treatment device by the conveying mechanism. The upper argon spraying and cooling mechanism (3) and the lower argon spraying and cooling mechanism (4) simultaneously spray high-pressure argon onto the upper and lower surfaces of the steel pipe. The argon heated on the steel pipe is attracted by the circulating fan (9) at the top and flows through the shell and tube water cooling heat exchanger (12) to be cooled again. The cooled argon then passes through the argon circulation pipeline (10) and is sprayed onto the surface of the steel pipe again through the upper argon spraying and cooling mechanism (3) and the lower argon spraying and cooling mechanism (4) to cool it down. S3. The temperature detection devices at the inlet and outlet of the argon solution heat treatment device transmit the temperature data at both ends to the controller. The controller automatically analyzes and monitors the cooling rate of the steel pipe. When the cooling rate of the steel pipe is lower than the set rate, first, the circulating fan (9) will increase the frequency of the motor to increase the fan speed and improve the argon circulation volume. If the cooling rate still cannot reach the target value after the frequency of the circulating fan (9) reaches the set maximum value, then the controller will increase the argon flow rate by adjusting the electric butterfly valve on the argon supply pipe (11) to increase the spraying speed and flow rate of the argon sprayed by the upper argon spraying and cooling mechanism (3) and the lower argon spraying and cooling mechanism (4) to reach the target cooling rate.

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