A roller hearth furnace with a balanced internal gas pressure and a protective atmosphere for bright solution treatment.

Abstract

This utility model discloses a roller-hearth type protective atmosphere bright solution furnace with balanced internal gas pressure. The gas pressure at both ends of the rapid cooling section is basically balanced, and the gas pressure in the gas exchange section and the slow cooling section is also basically balanced, effectively isolating the furnace from the external oxidizing atmosphere. The roller-hearth type protective atmosphere bright solution furnace of this utility model includes, along the material flow direction, interconnected gas exchange section, heating section, rapid cooling section, and slow cooling section. The rapid cooling section has a cooling chamber and an air inlet pipe connected to the cooling chamber. The rapid cooling section also has a gas cooling circulation device for extracting process gas from the cooling chamber for cooling and pumping the cooled low-temperature process gas back into the air inlet pipe. A process gas inlet is provided between the heating section and the rapid cooling section for pumping low-temperature process gas into the chambers of the heating section and the rapid cooling section. The air inlet pipe and the process gas inlet are located at the inlet and outlet ends of the rapid cooling section, respectively.

Description

Technical Field

[0001] This utility model relates to the field of metal heat treatment, and in particular to a roller hearth type protective atmosphere bright solution furnace with uniform internal gas pressure. Background Technology

[0002] Stainless steel pipe brightening and solution treatment equipment is used in the "solution heat treatment" process of stainless steel pipe production. After the "solution heat treatment" process, the stainless steel pipe needs to achieve the following characteristics: bright finish, excellent corrosion resistance, and good microstructure and properties.

[0003] "Solution treatment" refers to a heat treatment process in which an alloy is heated to a high-temperature single-phase region and held at that temperature, allowing the excess phase to fully dissolve into the solid solution, followed by rapid cooling to obtain a supersaturated solid solution. Improving the performance of stainless steel requires preventing surface decarburization and the formation of a decarburized layer during the solution treatment process. The main cause of decarburization is the reaction between carbon atoms on the surface of the stainless steel pipe and the oxidizing atmosphere in the treatment medium during solution heat treatment. Controlling decarburization hinges on controlling the oxidizing atmosphere within the furnace. Among oxidizing atmospheres, water vapor has the strongest decarburizing ability, followed by O2.

[0004] Regarding corrosion resistance, if carbon atoms in the furnace gain sufficient energy to penetrate the steel surface during solution heat treatment, passively increasing the carbon content, the increased carbon content will reduce the stainless steel's resistance to intergranular corrosion, thus reducing its stainless steel's ability to rust. Controlling this "carbon increase" hinges on controlling the carbon source introduced into the furnace. In the stainless steel pipe manufacturing process, the lubricant used in the lubrication process before cold rolling and the hydrocarbon cleaning agent used in the degreasing process before solution heat treatment are the main "carbon sources." Preventing "carbon increase" hinges on controlling the formation of "active carbon atoms."

[0005] For the rapid cooling in the solution treatment process, existing technologies use a pure hydrogen atmosphere introduced into the furnace as the cooling medium. While hydrogen has excellent cooling properties, its characteristics also pose significant challenges to the sealing performance of the equipment and create safety risks during daily use.

[0006] In addition, the protective atmosphere is generally introduced into the furnace in the rapid cooling section, where the gas pressure is the highest. The further away from the rapid cooling section in the furnace, the lower the gas pressure becomes, and the weaker the ability to block outside air becomes, making it unable to effectively isolate the oxidizing atmosphere. Moreover, due to the large temperature difference between the heating section upstream of the rapid cooling section and the slow cooling section downstream, the gas pressure at both ends of the rapid cooling section is not balanced, which affects the product quality of stainless steel pipes and brings considerable safety hazards.

[0007] Therefore, there is an urgent need for a roller hearth protective atmosphere bright solution furnace that can effectively block external oxidizing atmosphere and maintain a relatively balanced internal gas pressure at both ends of the rapid cooling section to overcome the above-mentioned defects. Utility Model Content

[0008] The purpose of this invention is to provide a roller hearth type protective atmosphere bright solution furnace that effectively blocks external oxidizing atmosphere and maintains a relatively balanced internal gas pressure at both ends of the rapid cooling section.

[0009] To achieve the above objectives, the present invention provides a roller hearth type protective atmosphere bright solution furnace with uniform in-furnace gas pressure, which includes, along the material flow direction, interconnected gas exchange section, heating section, rapid cooling section, and slow cooling section. The rapid cooling section has a cooling chamber and is equipped with an air inlet pipe connected to the cooling chamber. The rapid cooling section is also equipped with a gas cooling circulation device for extracting process gas from the cooling chamber for cooling and pumping the cooled low-temperature process gas into the air inlet pipe. A process gas inlet is provided between the heating section and the rapid cooling section for pumping low-temperature process gas into the chambers of the heating section and the rapid cooling section. The process gas inlet and the air inlet pipe are located at the inlet end and outlet end of the rapid cooling section, respectively.

[0010] Preferably, the cross-sectional area of ​​the ventilation section is smaller than that of the heating section, the cross-sectional area of ​​the heating section is smaller than that of the rapid cooling section, and the cross-sectional area of ​​the slow cooling section is smaller than that of the rapid cooling section.

[0011] Preferably, the gas cooling circulation device includes a return air duct, a heat exchanger, a fan, and an internal jet cooling device. The internal jet cooling device is installed in the cooling chamber. The first end of the return air duct is connected to the cooling chamber, the second end of the return air duct is connected to the heat exchanger, the heat exchanger is connected to the fan, and the inlet air duct is connected to the fan. The internal jet cooling device sprays low-temperature process gas onto the steel entering the cooling chamber. After heat exchange with the steel, the process gas in the cooling chamber flows sequentially through the return air duct, the heat exchanger, the fan, the inlet air duct, and the internal jet cooling device, and circulates continuously.

[0012] Preferably, the return air duct, heat exchanger, fan, and air inlet duct are located outside the cooling chamber.

[0013] Preferably, the rapid cooling section forms sidewalls surrounding the cooling chamber on both sides along the flow direction, and at least one of the side walls of the rapid cooling section has an air duct forming inside the cavity. The air duct is connected to the second end of the air inlet pipe, and the internal spray cooling device is connected to the air duct.

[0014] Preferably, the end of the air inlet duct that connects to the rapid cooling section branches into two air inlet branches. The sidewalls include a first sidewall and a second sidewall. One of the two air inlet branches is connected to the air duct in the first sidewall, and the other of the two air inlet branches is connected to the air duct in the second sidewall.

[0015] Preferably, the rapid cooling section has a cooling interlayer between the air duct and the cooling chamber.

[0016] Preferably, it also includes a feeding section and a discharging section. The feeding section, ventilation section, heating section, rapid cooling section, slow cooling section and discharging section are arranged sequentially along the material flow direction. Conveying roller groups for conveying steel along the material flow direction are passed through the feeding section, ventilation section, heating section, rapid cooling section, slow cooling section and discharging section. The internal spray cooling device includes multiple air knives located above and / or below the conveying roller groups. The cooling jacket has a gas connection port. The air knives are connected to the air duct through the gas connection port. The air outlet of the air knives faces the conveying roller groups.

[0017] Preferably, the internal jet cooling device also includes an inflator located on one side of the air outlet of the air knife. The diameter of the air outlet of the air knife gradually decreases towards the inflator. The inflator is provided with an air guide channel, which is aligned with the air outlet of the air knife. The air guide channel directs the input process gas to the conveying roller group. One of the two adjacent air knives is connected to the air duct of the first side wall, and the other of the two adjacent air knives is connected to the air duct of the second side wall.

[0018] Preferably, the connection between the ventilation section and the heating section is constricted relative to the internal space, the connection between the heating section and the rapid cooling section is constricted relative to the internal space, and the connection between the slow cooling section and the rapid cooling section is constricted relative to the internal space.

[0019] Compared to existing technologies, this system interconnects the feeding section, ventilation section, heating section, rapid cooling section, slow cooling section, and discharge section. Process gas is introduced in the rapid cooling section and enters the heating and ventilation sections through the gaps between these sections. Positive pressure is generated in the heating and ventilation sections, promptly removing and blocking the carbon source introduced into the furnace outside the high-temperature zone. It also promptly removes carbon-containing atmosphere and water vapor from the furnace, thus reducing carbon atom production and solving the common "carbon increase" problem in stainless steel tube solution treatment equipment. Furthermore, the interconnected sections allow for the entire equipment to be filled with process gas by injecting process gas into a single section of the rapid cooling section. The process gas inlet and air inlet duct are located at the inlet and outlet ends of the rapid cooling section, respectively. Low-temperature process gas is introduced into the heating and rapid cooling sections through the inlet. This effectively creates a reliable gas flow path, preventing the high-velocity process gas from entering the heating section. Furthermore, by injecting the gas at the tail end of the heating section, it forces the process gas to move towards its inlet, opposite to the direction of movement of the stainless steel pipe, thus preventing the entry of oxidizing atmospheres until it exits through the outlet of the ventilation section, achieving the desired flow field function. In addition, by placing the process gas inlet between the heating and rapid cooling sections, with the inlet and air inlet duct located at the inlet and outlet ends of the rapid cooling section, respectively, the gas pressure at both ends of the rapid cooling section is essentially balanced. Ultimately, this also ensures that the gas pressure in the ventilation and slow cooling sections is essentially balanced, effectively blocking external oxidizing atmospheres, ensuring the production quality of the stainless steel pipes, and reducing the risk of safety hazards. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the roller-bottom type protective atmosphere bright solution furnace with uniform internal gas pressure of this utility model.

[0021] Figure 2 This is a schematic diagram of the structure of the rapid cooling section and the gas cooling circulation device of this utility model when assembled together.

[0022] Figure 3 yes Figure 2 The structure shown is a top view with the heat exchanger and part of the return air duct hidden.

[0023] Figure 4 It is along Figure 3 The sectional view obtained after cutting along line segment CC.

[0024] Figure 5 It is along Figure 2 The sectional view obtained after cutting along line segment AA.

[0025] Figure 6 It is along Figure 2 The sectional view obtained after cutting the middle BB line segment.

[0026] Figure 7This is a schematic diagram of the internal jet cooling device spraying low-temperature process gas onto the stainless steel pipe conveyed by the conveyor roller assembly to cool it. Detailed Implementation

[0027] To explain the technical content and structural features of this utility model in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0028] This utility model discloses a roller hearth type protective atmosphere bright solution furnace with uniform internal gas pressure, used for bright solution treatment of steel.

[0029] In the solution treatment process of stainless steel, the most critical aspect is controlling the cooling rate during the rapid cooling phase. Taking 1Gr18Ni19 austenitic stainless steel as an example, the solubility of carbon in austenitic stainless steel at room temperature is very low, approximately 0.02%~0.03% (mass fraction). However, under normal circumstances, the carbon content of austenitic stainless steel is >0.02%~0.03% (mass fraction). Therefore, carbon is usually dissolved in the quenched austenite, which requires heating the austenite to around 950℃~1150℃. However, during the cooling process from 950℃~1150℃ to room temperature, if the austenitic stainless steel remains in the 850℃~450℃ temperature range, or more specifically, the 850℃~650℃ temperature range for an extended period, austenitic stainless steel will undergo "sensitization," resulting in "intergranular corrosion." This necessitates that the rapid cooling rate of the stainless steel meets relevant requirements.

[0030] Traditionally, water is used as a cooling medium. However, water has extremely strong oxidizing properties, which can lead to decarburization on the surface of steel. The oxygen in the cooling water also negatively impacts the shine of the steel. Therefore, cooling solutions using gas instead of water have emerged on the market. This invention uses process gas as the cooling medium, primarily composed of hydrogen (H2) and nitrogen (N2), but is not limited to hydrogen and nitrogen; other substances can be used depending on the specific application. This solution employs 70%–80% N2 and 20%–30% H2. Nitrogen acts as an inert atmosphere, isolating oxygen and preventing oxidation, while hydrogen acts as a reducing atmosphere, reducing the oxide layer on the steel surface to achieve a "bright" finish. In the embodiments provided in this invention, the steel is stainless steel pipe, but it should be understood that it is not limited to stainless steel pipe; steel plates, steel bars, etc., can be used depending on the actual needs.

[0031] like Figure 1 , Figure 2 , Figure 3 and Figure 4As shown, the roller hearth type protective atmosphere bright solution furnace 1000 includes, along the material flow direction, interconnected feeding section 100, ventilation section 200, heating section 300, rapid cooling section 400, slow cooling section 500, and discharge section 600. The rapid cooling section 400 has a cooling chamber 410 and is equipped with an air inlet duct 420 communicating with the cooling chamber 410. The rapid cooling section 400 also has a gas cooling circulation device 430 for extracting process gas from the cooling chamber 410 for cooling and pumping the cooled low-temperature process gas back into the air inlet duct 420. A process gas inlet 440 is provided between the heating section 300 and the rapid cooling section 400 for pumping low-temperature process gas into the chambers of both sections. The air inlet duct 420 and the process gas inlet 440 are located at the inlet and outlet ends of the rapid cooling section 400, respectively.

[0032] This invention utilizes an air inlet duct 420 and a gas cooling circulation device 430. By introducing low-temperature process gas through the air inlet duct 420, the process gas originally intended for the furnace is used as a cooling medium, eliminating the problems and costs associated with using other cooling media. Furthermore, the flow rate of the low-temperature process gas entering the cooling chamber 410 thoroughly agitates the atmosphere within the chamber, effectively mixing the lighter hydrogen (H2) and heavier nitrogen (N2) gases, preventing significant atmosphere stratification. A small amount of the process gas flowing freely from the rapid cooling section 400 is diverted along with the stainless steel pipe to the slow cooling section 500. This diverted gas creates a "protective + reducing" atmosphere in the slow cooling section 500, ensuring that the stainless steel pipe does not oxidize in the low-temperature region and providing sufficient protection for the "bright solution heat treatment" of the stainless steel pipe.

[0033] The feeding section 100, ventilation section 200, heating section 300, rapid cooling section 400, slow cooling section 500, and discharge section 600 are interconnected. Process gas is introduced in the rapid cooling section 400 and enters the heating section 300 and ventilation section 200 through the gaps between the sections. Positive pressure is generated in the heating section 300 and ventilation section 200, which promptly removes and blocks the carbon source introduced into the furnace from the high-temperature section, and also promptly discharges carbon-containing atmosphere and water vapor from the furnace. By reducing the generation of carbon atoms, the common "carbon increase" problem in stainless steel tube solution treatment equipment is solved. Moreover, since the above sections are interconnected, process gas can be injected into the rapid cooling section 400 to achieve full coverage of process gas throughout the entire equipment line.

[0034] The process gas inlet 440 and the air inlet pipe 420 are located at the inlet and outlet ends of the rapid cooling section 400, respectively. Low-temperature process gas is introduced into the heating section 300 and the rapid cooling section 400 through the process gas inlet 440. On the one hand, this is equivalent to forming a reliable gas component, blocking the high-velocity process gas in the rapid cooling section 400 from entering the heating section 300. On the other hand, it is injected at the tail end of the heating section 300, forcing the process gas in the heating section 300 to move towards the inlet position of the heating section 300, opposite to the movement direction of the stainless steel pipe, blocking the entry of oxidizing atmosphere, until it is discharged from the outlet of the ventilation section 200, thus achieving the function of the flow field. Furthermore, by setting a process gas inlet 440 between the heating section 300 and the rapid cooling section 400, with the process gas inlet 440 and the air inlet pipe 420 located at the inlet and outlet ends of the rapid cooling section 400 respectively, the gas pressure at both ends of the rapid cooling section 400 is basically balanced. Ultimately, the gas pressure in the ventilation section 200 and the slow cooling section 500 is also basically balanced, effectively blocking the external oxidizing atmosphere, ensuring the production quality of stainless steel pipes, and reducing the risk of safety hazards.

[0035] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the gas cooling circulation device 430 includes a return air duct 431, a heat exchanger 432, a fan 433, and an internal jet cooling device 434. The internal jet cooling device 434 is installed in the cooling chamber 410. The first end of the return air duct 431 is connected to the cooling chamber 410, and the second end of the return air duct 431 is connected to the heat exchanger 432. The heat exchanger 432 is connected to the fan 433, and the inlet air duct 420 is connected to the fan 433. The internal jet cooling device 434 sprays low-temperature process gas onto the steel entering the cooling chamber 410. After heat exchange with the steel, the process gas in the cooling chamber 410 flows sequentially through the return air duct 431, the heat exchanger 432, the fan 433, the inlet air duct 420, and the internal jet cooling device 434, and circulates continuously.

[0036] Furthermore, the return air duct 431, heat exchanger 432, fan 433, and inlet air duct 420 are located outside the cooling chamber 410. By placing the return air duct 431, heat exchanger 432, fan 433, and inlet air duct 420 outside the cooling chamber 410, and only installing the internal jet cooling device 434 inside the cooling chamber 410, excessive structures are avoided in the cooling chamber 410, simplifying installation. Moreover, the vibrations generated by the operation of the heat exchanger 432 and fan 433 will not be transmitted to the rapid cooling section 400, eliminating the need for a stirring fan to agitate the airflow for cooling within the rapid cooling section 400, and preventing vibrations from the stirring fan affecting the sealing of the rapid cooling section 400. In addition, by placing the heat exchanger 432, fan 433, return air duct 431 and inlet air duct 420 outside the rapid cooling section 400, the process gas experiences less obstruction and influence when flowing in the cooling chamber 410, and the flow field in the cooling chamber 410 becomes simpler, making it easier to control pressure and flow rate.

[0037] Figure 1 , Figure 2 , Figure 4 and Figure 6 The logistics direction is shown.

[0038] like Figures 2 to 6 As shown, the rapid cooling section 400 forms the inlet and outlet of the cooling chamber 410 at both ends along the material flow direction. Side walls surrounding the cooling chamber 410 are formed on both sides of the rapid cooling section 400 along the material flow direction. An airflow duct 450 is formed within the inner cavity of at least one of the side walls of the rapid cooling section 400. The airflow duct 450 is connected to the second end of the air inlet pipe 420, and the internal jet cooling device 434 is connected to the airflow duct 450. Preferably, in the embodiment provided by this utility model, airflow ducts 450 are formed within the inner cavities of both side walls of the rapid cooling section 400, but this is not a limitation. The airflow duct 450 is connected to the second end of the air inlet pipe 420, and the internal jet cooling device 434 is connected to the airflow duct 450. The airflow ducts 450 are provided within the side walls of the rapid cooling section 400, serving as part of the airflow ducts 450, optimizing the structural form and functioning as a storage and redistribution point for circulating airflow. Preferably, the air duct 450 extends along the flow direction to both ends of the rapid cooling section 400 to achieve better storage of process gases and facilitate the distribution of process gases.

[0039] like Figures 2 to 6As shown, the air inlet duct 420 branches off at one end where it connects to the rapid cooling section 400, forming two air inlet branch ducts 421. The sidewalls include a first sidewall and a second sidewall. One of the two air inlet branch ducts 421 connects to the air duct 450 within the first sidewall, and the other connects to the air duct 450 within the second sidewall. The two air inlet branch ducts 421 facilitate connection with the air ducts 450 within the first and second sidewalls. To facilitate the injection of process gas, the air inlet duct 420 is provided with an injection port 422, through which process gas can be easily input and replenished. Preferably, the injection port 422 is positioned close to the two air inlet branch ducts 421, but this is not a limitation.

[0040] Furthermore, the rapid cooling section 400 includes a cooling jacket 460 between the air duct 450 and the cooling chamber 410. This cooling jacket 460 can further cool the cooling chamber 410 and the process gas, improving the cooling effect. Preferably, the cooling jacket 460 uses water cooling; however, depending on actual needs, electric drive, air cooling, or other methods can also be used. In addition, the cooling jacket 460 is a solid structure, effectively physically isolating the cooling chamber 410 and the air duct 450, preventing heat transfer between them.

[0041] like Figures 1 to 7 As shown, conveyor roller sets 700, arranged along the material flow direction, are installed throughout the feeding section 100, ventilation section 200, heating section 300, rapid cooling section 400, slow cooling section 500, and discharge section 600 to automatically convey the steel. The internal spray cooling device 434 includes multiple air knives 4341 located above and below the conveyor roller sets 700. A cooling jacket 460 has a gas connection port 461 through which the air knives 4341 are connected to the air duct 450. The air outlet of the air duct 4641 faces the conveyor roller sets 700.

[0042] Preferably, the air knife 4341 and the gas connection port 461 can be connected via a flange, but other methods such as welding or sleeve connection are also possible. The low-temperature process gas output from the outlet of the air knife 4341 cools the steel conveyed by the conveyor roller group 700. Moreover, multiple air knives 4341 are installed above and below the conveyor roller group 700, which can simultaneously cool the upper and lower sides of the steel, ensuring uniform air supply and effective cooling of the steel.

[0043] Furthermore, the internal jet cooling device 434 also includes an incrementer 4342 located on one side of the air knife 4341. The diameter of the air outlet of the air knife 4341 gradually decreases toward the incrementer 4342. The incrementer 4342 is provided with an air guide channel 4343, which is aligned with the air outlet of the air knife 4341. The air guide channel 4343 guides the input process gas to the conveying roller group 700. One of the two adjacent air knives 4341 is connected to the air duct 450 in the first side wall, and the other of the two adjacent air knives 4341 is connected to the air duct 450 in the second side wall.

[0044] Process gas ejected from the outlet of air knife 4341 flows into air guide channel 4343, which directs the incoming process gas to conveyor roller assembly 700 to cool the steel conveyed on the roller assembly 700. Through the action of air knife 4341 and incrementer 4342, the low-temperature process gas is forcefully injected onto the steel conveyed by the conveyor roller assembly 700, resulting in rapid, thorough, and comprehensive heat exchange with the steel.

[0045] In this invention, the cross-sectional area of ​​the ventilation section 200 is smaller than that of the heating section 300. The connection between the ventilation section 200 and the heating section 300 is constricted relative to the internal space. The cross-sectional area of ​​the heating section 300 is smaller than that of the rapid cooling section 400. The connection between the heating section 300 and the rapid cooling section 400 is constricted relative to the internal space. The cross-sectional area of ​​the slow cooling section 500 is smaller than that of the rapid cooling section 400. The connection between the slow cooling section 500 and the rapid cooling section 400 is constricted relative to the internal space. Low-temperature process gas is injected from the rapid cooling section 400 and splits into two streams flowing to both ends of the rapid cooling section 400. This ensures the air pressure of the roller-bottom protective atmosphere bright solution furnace, blocks the entry of oxidizing atmosphere, and effectively prevents decarburization.

[0046] The following is a brief description of the working process of the roller-hearth protective atmosphere bright solution furnace 1000 with balanced internal gas pressure of this utility model: Stainless steel pipes are placed on the conveying roller group 700, which transports the stainless steel pipes along the material flow direction. The stainless steel pipes flow sequentially through the feeding section 100, the ventilation section 200, the heating section 300, the rapid cooling section 400, the slow cooling section 500, and the discharge section 600. Low-temperature process gas is introduced into the rapid cooling section 400 through the air inlet duct 420 and the process gas inlet 440. A portion of the low-temperature process gas in the rapid cooling section 400 flows towards the heating section 300 and the ventilation section 200. When it flows into the ventilation section 200, the temperature inside the ventilation section 200 rises (below 950℃), venting the residual air inside the ventilation section 200, evaporating residual moisture on the surface of the stainless steel pipe, removing residual carbonaceous substances from the surface of the stainless steel pipe, and preheating the stainless steel pipe. Next, the conveyor roller group 700 feeds the stainless steel tube into the heating section 300, where the temperature rises to 950~1150℃, causing all or most of the carbides in the stainless steel tube to dissolve, and the carbon to dissolve in the austenite. The conveyor roller assembly 700 feeds the stainless steel pipe into the rapid cooling section 400. The process gas cooled by the heat exchanger 432 is sent into the rapid cooling section 400 through the air inlet pipe 420 by the fan 433. Near the rapid cooling section 400, the air inlet pipe 420 is split into two branches 421. The low-temperature process gas is input into the duct 450 from the air inlet branch pipe 421. The low-temperature process gas flows out through the gas connection port 461 to the air knife 4341. After passing through the air knife 4341 and the inflation device 4342, the low-temperature process gas is forcefully sprayed onto the surface of the stainless steel pipe conveyed by the conveyor roller assembly 700, rapidly cooling the stainless steel pipe from 1150℃ to the specified temperature. The process gas that has completed heat exchange with the stainless steel pipe flows out to the return air duct 431 and then through the heat exchanger 432 for further heat exchange and cooling. Afterwards, it is pumped by the fan 433 back into the inlet air duct 420 and returned to the cooling chamber 410, continuously circulating in this manner. The conveyor roller assembly 700 then sends the cooled stainless steel pipe into the slow cooling section 500, where its temperature is gradually reduced to the discharge temperature. Finally, it is conveyed to the discharge section 600 for output and packaging.

[0047] The above-disclosed examples are merely preferred embodiments of the present utility model and should not be construed as limiting the scope of the present utility model. Therefore, any equivalent variations made in accordance with the claims of the present utility model shall fall within the scope of the present utility model.

Claims

1. A roller-hearth type protective atmosphere bright solution furnace with uniform internal gas pressure, characterized in that, Along the logistics direction, it sequentially includes an interconnected ventilation section, heating section, rapid cooling section, and slow cooling section. The rapid cooling section has a cooling chamber and is equipped with an air inlet duct communicating with the cooling chamber. The rapid cooling section is also equipped with a gas cooling circulation device for extracting process gas from the cooling chamber for cooling and pumping the cooled low-temperature process gas into the air inlet duct. Between the heating section and the rapid cooling section, there is a process gas inlet for pumping low-temperature process gas into the chambers of the heating section and the rapid cooling section. The process gas inlet and the air inlet duct are located at the inlet end and outlet end of the rapid cooling section, respectively.

2. The roller hearth type protective atmosphere bright solution furnace according to claim 1, characterized in that, The cross-sectional area inside the ventilation section is smaller than that inside the heating section, the cross-sectional area inside the heating section is smaller than that inside the rapid cooling section, and the cross-sectional area inside the slow cooling section is smaller than that inside the rapid cooling section.

3. The roller hearth type protective atmosphere bright solution furnace according to claim 1, characterized in that, The gas cooling circulation device includes a return air duct, a heat exchanger, a fan, and an internal jet cooling device. The internal jet cooling device is installed in the cooling chamber. The first end of the return air duct is connected to the cooling chamber, and the second end of the return air duct is connected to the heat exchanger. The heat exchanger is connected to the fan, and the air inlet duct is connected to the fan. The internal jet cooling device sprays low-temperature process gas onto the steel entering the cooling chamber. After heat exchange with the steel, the process gas in the cooling chamber flows sequentially through the return air duct, the heat exchanger, the fan, the air inlet duct, and the internal jet cooling device, and circulates continuously.

4. The roller hearth type protective atmosphere bright solution furnace according to claim 3, characterized in that, The return air duct, the heat exchanger, the fan, and the inlet air duct are located outside the cooling chamber.

5. The roller hearth type protective atmosphere bright solution furnace according to claim 3, characterized in that, The rapid cooling section forms sidewalls surrounding the cooling chamber on both sides along the material flow direction. At least one of the side walls of the rapid cooling section has an internal cavity with a diversion air duct. The diversion air duct is connected to the second end of the air inlet pipe. The internal jet cooling device is connected to the diversion air duct.

6. The roller hearth protective atmosphere bright solution furnace according to claim 5, characterized in that, The air inlet duct branches off at one end where it connects to the rapid cooling section to form two air inlet branches. The sidewall includes a first sidewall and a second sidewall. One of the two air inlet branches is connected to the air duct in the first sidewall, and the other of the two air inlet branches is connected to the air duct in the second sidewall.

7. The roller hearth protective atmosphere bright solution furnace according to claim 6, characterized in that, The rapid cooling section has a cooling interlayer between the air duct and the cooling chamber.

8. The roller hearth type protective atmosphere bright solution furnace according to claim 7, characterized in that, It also includes a feeding section and a discharging section. The feeding section, the ventilation section, the heating section, the rapid cooling section, the slow cooling section, and the discharging section are arranged sequentially along the material flow direction. Conveying roller groups for conveying steel are arranged along the material flow direction and pass through the feeding section, the ventilation section, the heating section, the rapid cooling section, the slow cooling section, and the discharging section. The internal spray cooling device includes multiple air knives located above and / or below the conveying roller groups. The cooling jacket has a gas connection port. The air knives are connected to the air duct through the gas connection port. The air outlets of the air knives face the conveying roller groups.

9. The roller hearth type protective atmosphere bright solution furnace according to claim 8, characterized in that, The internal jet cooling device also includes an inflator located on one side of the air outlet of the air knife. The diameter of the air outlet of the air knife gradually decreases towards the inflator. The inflator is provided with an air guide channel, which is aligned with the air outlet of the air knife. The air guide channel directs the input process gas to the conveying roller group. One of two adjacent air knives is connected to the air duct in the first side wall, and the other of two adjacent air knives is connected to the air duct in the second side wall.

10. The roller hearth type protective atmosphere bright solution furnace according to claim 1, characterized in that, The connection between the ventilation section and the heating section is constricted relative to the internal space; the connection between the heating section and the rapid cooling section is constricted relative to the internal space; and the connection between the slow cooling section and the rapid cooling section is constricted relative to the internal space.

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