Titanium alloy plate-fin heat exchanger vacuum brazing equipment with air cooling system and application

Abstract

The invention discloses titanium alloy plate-fin heat exchanger vacuum brazing equipment with an air cooling system and application, and relates to the field of brazing. The vacuum system is used for discharging gas in the furnace body to obtain a vacuum environment; the furnace pipe is arranged in the furnace body; and the gas circulating cooling system is connected with the furnace body to form a closed cavity for cooling. The production efficiency is improved through the gas cooling circulation flow field design, the specific structure of the gas circulation cooling system and the cooling process control mode. The problem that the cooling uniformity of the plate-fin heat exchangers arranged in a staggered mode under the forced circulation cooling condition is difficult to control is solved, the brazing production efficiency is greatly improved, and the situation that the quality of brazing seams is seriously affected by out-of-tolerance thermal stress deformation is avoided.

Description

Technical Field

[0001] The present invention belongs to the brazing technology in the technical field of high-end equipment manufacturing, and specifically relates to a vacuum brazing device for a titanium alloy plate-fin heat exchanger with an air cooling system and an application thereof. Background Art

[0002] Since large-size titanium alloy plate-fin heat exchangers have the characteristics of multi-layer combination and interlayer self-shielding structure, the use of traditional vacuum brazing equipment usually has no gas circulation cooling system and adopts furnace cooling, which has the problem of slow cooling speed, resulting in long brazing process cycle and low production efficiency. If the existing gas circulation cooling system structure is adopted, the gas spray cooling method of 360° uniformly distributed along the circumferential direction or unidirectional blowing is generally adopted, it is difficult to ensure the cooling uniformity of the staggered plate-fin heat exchanger structure, which often leads to large thermal stress deformation, seriously affecting the quality of the weld and reducing the compressive strength of the high-performance plate-fin heat exchanger. Summary of the invention

[0003] In view of the above problems, the present invention provides a titanium alloy plate-fin heat exchanger vacuum brazing device with an air cooling system and its application, which can achieve rapid and uniform cooling of large-sized titanium alloy plate-fin heat exchangers.

[0004] According to one aspect of the present invention, a titanium alloy plate-fin heat exchanger vacuum brazing device with an air cooling system is provided, and the titanium alloy plate-fin heat exchanger vacuum brazing device with an air cooling system comprises: a furnace body, which is used to provide a vacuum environment and accommodate parts to be welded; a vacuum system, which is connected to the furnace body, and is used to discharge the gas in the furnace body to obtain a vacuum environment; a furnace core, which is arranged in the furnace body, and the furnace core is provided with a side air inlet and a side small heat insulation screen in the first direction, and a rear return air inlet and a rear small heat insulation screen in the second direction of the furnace core, the side air inlet and the rear return air inlet are used to guide the airflow in and out of the furnace core, and the side small heat insulation screen and the rear small heat insulation screen are used to maintain the furnace core. In a high-temperature state, the furnace is provided with front and rear openings, and is provided with a furnace rear cover and a furnace front cover; a gas circulation cooling system, the gas circulation cooling system is connected with the furnace body to form a closed chamber, the gas circulation cooling system comprises a circulation fan, a furnace inlet duct, a furnace outlet duct and a heat exchanger, the circulation fan blows the low-temperature gas into between the furnace and the furnace body through the furnace inlet duct, the low-temperature gas bypasses the small heat insulation screen on the furnace side and flows in from the furnace inlet on the furnace side, the high-temperature gas after fully cooling the brazed plate-fin heat exchanger flows out through the furnace rear outlet, bypasses the small heat insulation screen at the rear of the furnace and enters the furnace outlet duct, flows through the heat exchanger and is cooled to low-temperature gas, and the low-temperature gas is sucked into the next forced circulation by the circulation fan.

[0005] Furthermore, the furnace chamber air inlet duct includes a front sealing plate, a tee and a double air inlet duct, the main pipe interface of the tee is connected to the circulating fan, and the two branch pipe interfaces of the tee are connected to the double air inlet duct, so as to introduce the low-temperature airflow of the circulating fan into the furnace body through the tee and the double air inlet duct, and the two ends of the front sealing plate are respectively connected to the inner wall of the furnace body and the outer wall of the furnace chamber, and the front sealing plate is used to guide the low-temperature airflow to bypass the small heat insulation screen on the furnace chamber side and flow into the air inlet on the furnace chamber side.

[0006] Furthermore, the furnace outlet air duct includes an air guide hood, a collector and a return air duct connected in sequence, the heat exchanger is arranged inside the furnace outlet air duct, the air guide hood is arranged outside the furnace, the air guide hood is connected to the heat exchanger, connecting the rear return air port and the collector of the furnace, one end of the return air duct is connected to the air inlet of the circulation fan, and the other end of the return air duct is connected to the air outlet at the rear end center of the furnace body.

[0007] Furthermore, a load thermocouple is arranged in the furnace.

[0008] Furthermore, a plurality of load thermocouples are provided, which are respectively arranged on the surface and the core of the heat exchanger. When the temperature difference measured by the load thermocouple is greater than the set value, the rotation speed of the circulating fan is reduced or the gas pressure in the furnace body is reduced, thereby reducing the cooling speed and reducing the temperature difference between the core and the surface of the product.

[0009] Furthermore, the direction of the airflow entering the furnace body from the double air inlet ducts is parallel to the side walls of the furnace and perpendicular to the rear cover of the furnace.

[0010] Furthermore, the length of the air guide cover can be adjusted to ensure contact with the furnace rear cover during assembly.

[0011] Furthermore, the collector is in the shape of a cone ring, the bottom of the cone faces the heat exchanger, and the inner diameter of the cone mouth is larger than the outer diameter of the return air duct.

[0012] Furthermore, the vacuum system includes a vacuum pump, a vacuum valve and a pipeline. The vacuum pump is connected to the furnace body through the pipeline, and a vacuum valve is arranged on the pipeline.

[0013] The invention discloses an application of a titanium alloy plate-fin heat exchanger vacuum brazing equipment with an air cooling system. The titanium alloy plate-fin heat exchanger vacuum brazing equipment is used in the vacuum brazing cooling of large-sized titanium alloy plate-fin heat exchangers to achieve a maximum core-surface temperature difference of 50°C, a cooling time of 2 to 3 hours, and an average cooling rate of 350 to 370°C / h.

[0014] By applying the technical solution of the present invention, the production efficiency is improved through the design of the gas cooling circulation flow field, the specific structure of the gas circulation cooling system, and the way of cooling process control. Specifically, compared with the traditional vacuum brazing equipment, a gas circulation cooling system is added. The gas circulation path and direction of the system are highly matched with the structural characteristics of the staggered arrangement of the plate-fin heat exchanger. There are both lateral airflow and longitudinal airflow, which can make all points inside the plate-fin heat exchanger cool at the same time. In addition, load thermocouples are arranged on the surface and core of the plate-fin heat exchanger respectively to measure the core-surface temperature in real time. When the temperature difference is greater than the set value, the rotation speed of the circulating fan is reduced or the gas pressure in the furnace body is reduced, thereby appropriately reducing the cooling speed and reducing the core-surface temperature difference of the product. The above scheme is adopted to change the current situation that the titanium alloy plate-fin heat exchanger can only be cooled slowly with the furnace, solve the problem that the cooling uniformity of the staggered plate-fin heat exchanger under forced circulation cooling conditions is difficult to control, greatly improve the brazing production efficiency, and avoid the thermal stress deformation tolerance that seriously affects the quality of the brazing weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram (top view) of a gas circulation for a high-efficiency vacuum brazing device for manufacturing a plate-fin heat exchanger provided in an embodiment of the present invention;

[0016] Figure 2 A schematic plan view (top view) of a high-efficiency vacuum brazing device for manufacturing a plate-fin heat exchanger provided in an embodiment of the present invention;

[0017] Figure 3 A front view of a vacuum brazing device provided by an embodiment of the present invention;

[0018] Figure 4 A right side view of a high-efficiency vacuum brazing device for manufacturing a plate-fin heat exchanger provided by an embodiment of the present invention;

[0019] Figure 5 It is a structural schematic diagram of a titanium alloy plate-fin heat exchanger.

[0020] The above drawings include the following reference numerals:

[0021] 10. Furnace body,

[0022] 20. Vacuum system, 21. Vacuum pump, 22. Vacuum valve, 23. Pipeline,

[0023] 30. Furnace, 31. Side air inlet, 32. Side small heat insulation screen, 33. Rear air outlet, 34. Rear small heat insulation screen, 35. Furnace rear cover, 36. Furnace front cover;

[0024] 40. Gas circulation cooling system, 41. Circulation fan, 411. Center inlet, 412. End outlet, 42. Furnace inlet air duct, 421. Front sealing plate, 422 T-joint, 423. Double air inlet duct, 43. Furnace outlet air duct, 431. Air guide cover, 432. Collector, 433. Return air duct, 44. Heat exchanger;

[0025] 50. Load thermocouple. DETAILED DESCRIPTION

[0026] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0029] like Figures 1 to 5As shown, according to a specific embodiment of the present invention, a titanium alloy plate-fin heat exchanger vacuum brazing equipment with an air cooling system is provided, including a furnace body 10, which is used to provide a vacuum environment and accommodate parts to be welded; a vacuum system 20, which is connected to the furnace body 10, and the vacuum system is used to discharge the gas in the furnace body 10 to obtain a vacuum environment; a furnace 30, wherein the furnace 30 is arranged in the furnace body 10, and a side air inlet 31 and a side small heat insulation screen 32 are arranged in the first direction of the furnace 30, and a rear return air inlet 33 and a rear small heat insulation screen 34 are arranged in the second direction of the furnace 30, the side air inlet 31 and the rear return air inlet 33 are used to guide the air flow in and out of the furnace 30, and the side small heat insulation screen 32 and the rear small heat insulation screen 34 are used to maintain the high temperature state in the furnace 30, and the furnace 30 is arranged with front and rear openings, and is provided with a furnace A rear cover 35 and a furnace front cover 36; a gas circulation cooling system 40, which is connected to the furnace body 10 to form a closed chamber. The gas circulation cooling system 40 includes a circulation fan 41, a furnace air inlet duct 42, a furnace air outlet duct 43 and a heat exchanger 44. The circulation fan 41 blows the low-temperature gas into between the furnace 30 and the furnace body 10 through the furnace air inlet duct 42. The low-temperature gas bypasses the small heat insulation screen 32 on the side of the furnace 30 and flows into the air inlet 31 on the side of the furnace 30. The high-temperature gas after fully cooling the brazed plate-fin heat exchanger flows out through the rear air outlet 33 of the furnace 30, bypasses the small heat insulation screen 34 at the rear of the furnace 30 and enters the furnace air outlet duct 43, flows through the heat exchanger 44 and is cooled to low-temperature gas, and the low-temperature gas is sucked into the next forced circulation by the circulation fan 41.

[0030] This configuration is applied to improve production efficiency through the design of gas cooling circulation flow field, the specific structure of the gas circulation cooling system, and the control of the cooling process. Specifically, compared with traditional vacuum brazing equipment, a gas circulation cooling system is added. The gas circulation path and direction of this system are highly matched with the structural characteristics of the staggered arrangement of the plate-fin heat exchanger. There are both horizontal and longitudinal airflows, which can enable all points inside the plate-fin heat exchanger to be cooled simultaneously. The above scheme changes the current situation that titanium alloy plate-fin heat exchangers can only be cooled slowly with the furnace, solves the problem of difficult control of cooling uniformity of staggered plate-fin heat exchangers under forced circulation cooling conditions, greatly improves brazing production efficiency, and avoids thermal stress deformation that seriously affects the quality of brazing welds.

[0031] Furthermore, if Figure 4As shown, in order to optimize the air intake air flow path, the furnace inlet duct 42 includes a front sealing plate 421, a tee 422 and a double air intake duct 423. The main pipe interface of the tee 422 is connected to the circulation fan 41, and the two branch pipe interfaces of the tee 422 are connected to the double air intake duct 423 to introduce the low-temperature airflow of the circulation fan 41 into the furnace body 10 through the tee 422 and the double air intake duct 423. The two ends of the front sealing plate 421 are respectively connected to the inner wall of the furnace body 10 and the outer wall of the furnace 30. The front sealing plate 421 is used to guide the low-temperature airflow to bypass the small heat insulation screen 32 on the side of the furnace 30 and flow into the air inlet 31 on the side of the furnace 30.

[0032] By applying this configuration, the low-temperature airflow generated by the circulating fan 41 can be distributed to both sides of the furnace 30 more evenly and efficiently by adopting the combined design of the three-way 422 and the double air inlet duct 423. This design effectively reduces the loss and turbulence of the airflow during the transmission process, so that the low-temperature airflow can enter the furnace 30 more directly and smoothly, thereby improving the heat exchange efficiency and accelerating the uniform distribution and temperature rise rate of the furnace. The design of the front sealing plate 421 cleverly guides the low-temperature airflow to bypass the small heat insulation screen 32 on the side of the furnace 30 and enter the furnace. This not only maintains the heat insulation effect of the small heat insulation screen, prevents the high temperature in the furnace from being directly radiated to the external structure, but also ensures the effective use of the low-temperature airflow. This design helps to reduce the ineffective loss of heat energy and reduce the energy consumption of the entire system. And its design allows the low-temperature airflow to circulate smoothly, which to a certain extent reduces the dust accumulation and pollutant deposition in the area around the furnace. In addition, this design also provides convenience for subsequent maintenance and cleaning work, reducing maintenance costs and difficulties.

[0033] Furthermore, if Figure 2 and Figure 3 As shown, in order to optimize the air flow path, the furnace outlet duct 43 includes an air guide cover 431, a collector 432 and a return air duct 433 which are connected in sequence, the heat exchanger 44 is arranged inside the furnace outlet duct 43, the air guide cover 431 is arranged on the outside of the furnace 30, the air guide cover 431 is connected to the heat exchanger 44, and the return air port 33 and the collector 432 at the rear of the furnace are connected, one end of the return air duct 433 is connected to the air inlet of the circulation fan 41, and the other end of the return air duct 433 is connected to the air outlet at the rear end center of the furnace body 10.

[0034] By applying this configuration, the heat exchanger 44 is directly arranged inside the furnace air outlet duct 43, especially connected to the air guide cover 431, so that the heat energy in the high-temperature gas discharged from the furnace 30 can be efficiently captured and recovered. This design ensures that the high-temperature gas can fully exchange heat with the heat exchanger before leaving the furnace, thereby improving the heat recovery efficiency.

[0035] Furthermore, if Figure 2 As shown, in order to accurately control the cooling speed, a load thermocouple 50 is provided in the furnace 30 .

[0036] Furthermore, if Figure 2 As shown, in order to reduce the temperature difference between the center and the surface of the product, a plurality of load thermocouples 50 are provided, which are respectively arranged on the surface and the center of the heat exchanger 44. When the temperature difference measured by the load thermocouple 50 is greater than the set value, the rotation speed of the circulation fan 41 is reduced or the gas pressure in the furnace body 10 is reduced, thereby reducing the cooling speed and reducing the temperature difference between the center and the surface of the product.

[0037] With this configuration, load thermocouples are arranged on the surface and core of the plate-fin heat exchanger to measure the core-surface temperature in real time. When the temperature difference is greater than the set value, the circulation fan rotation speed is reduced or the gas pressure in the furnace is reduced, thereby appropriately reducing the cooling speed and reducing the core-surface temperature difference of the product.

[0038] Furthermore, if Figure 1 As shown, in order to further improve the cooling efficiency, the direction of the airflow entering the furnace body 10 from the double air inlet duct 423 is parallel to the side wall of the furnace 30 and perpendicular to the rear cover of the furnace 30.

[0039] Furthermore, in order to enhance the compactness and integration of the system and improve the flexibility of the system, the length of the air guide cover 431 can be adjusted to ensure contact with the rear cover of the furnace during assembly.

[0040] Furthermore, in order to optimize the air flow distribution and reduce the pressure loss, the collector 432 is in the shape of a cone ring, the bottom of the cone faces the heat exchanger 44, and the inner diameter of the cone mouth is larger than the outer diameter of the return air duct 433.

[0041] Furthermore, in order to achieve precise control and rapid adjustment of the vacuum degree in the furnace, the vacuum system 20 includes a vacuum pump 21, a vacuum valve 22 and a pipeline 23. The vacuum pump 21 is connected to the furnace body 10 through the pipeline 23, and a vacuum valve 22 is provided on the pipeline 23.

[0042] In order to further understand the present invention, the following Figures 1 to 5 The vacuum brazing equipment for titanium alloy plate-fin heat exchanger with air cooling system of the present invention is described in detail. Figure 1 and Figure 2 As shown, the vacuum brazing equipment for titanium alloy plate-fin heat exchanger with air cooling system includes:

[0043] The furnace body 10 is used to provide a vacuum environment and accommodate the parts to be welded;

[0044] The vacuum system 20 includes a vacuum pump 21 , a vacuum valve 22 and a pipeline 23 . The vacuum pump 21 is connected to the furnace body 10 through the pipeline 23 , and the vacuum valve 22 is provided on the pipeline 23 .

[0045] The furnace 30 is arranged in the furnace body 10, and the furnace 30 includes a side air inlet 31, a side small heat insulation screen 32, a rear return air inlet 33, a rear small heat insulation screen 34, a furnace rear cover 35 and a furnace front cover 36. The furnace 30 is arranged with front and rear openings, and there are multiple side air inlets 31, which are evenly arranged on both sides of the furnace 30. The side small heat insulation screens 32 are installed on both sides of the furnace 30. Multiple rear return air inlets 33 are evenly arranged on the furnace rear cover 36, and the rear small heat insulation screen 32 is arranged on the furnace rear cover 36. A plurality of load thermocouples 50 are arranged in the furnace 30, which are arranged on the surface and the core of the heat exchanger 44 respectively.

[0046] The gas circulation cooling system 40 is connected to the furnace body 10 through a flange with a sealing ring to form a closed chamber. The gas circulation cooling system 40 includes a circulation fan 41, a furnace inlet air duct 42, a furnace outlet air duct 43 and a heat exchanger 4. In addition, the gas circulation cooling system can also adopt an internal circulation structure, and the circulation fan is directly connected to the furnace body.

[0047] The circulating fan 41, when the temperature difference measured by the load thermocouple 50 is greater than the set value, reduces the rotation speed of the circulating fan 41 or reduces the gas pressure in the furnace body 10, thereby reducing the cooling speed and reducing the temperature difference between the center and the surface of the product. The circulating fan 41 is arranged outside the furnace body 10 and is connected to the furnace body 10 through a pipeline. The circulating fan 41 has a central inlet 411 and an end outlet 412.

[0048] The furnace inlet air duct 42 includes a front sealing plate 421, a tee 422 and a double air inlet duct 423, which is an annular space with an outer circle and an inner square formed by the double air inlet duct, the inner wall of the furnace body, the outer side of the collector, the outer side of the air guide cover, the outer wall of the furnace body and the front sealing plate. The two air outlets of the double air inlet duct 423 are respectively connected to the air inlets arranged at the upper and lower ends of the rear end of the furnace body 10, and the air inlet is connected to the tee 422, which is connected to the air outlet of the circulation fan 41. The air flow direction from the double air inlet duct 423 into the furnace body 10 is parallel to the side wall of the furnace body and perpendicular to the rear cover of the furnace body. The front sealing plate 421 is close to the front cover of the furnace body, and its two ends are respectively connected to the inner wall of the furnace body 10 and the outer wall of the furnace body 30. The front sealing plate 421 is used to guide the low-temperature airflow to bypass the small heat insulation screen 32 on the side of the furnace body 30 and flow into the air inlet 31 on the side of the furnace body 30.

[0049] The furnace outlet duct 43 is connected to the furnace 30. The furnace outlet duct 43 is composed of an air guide cover 431, a collector 432 and a return air duct 433. The length of the air guide cover 431 is adjustable to ensure that it is in contact with the furnace rear cover during assembly, and to close the space from the furnace rear cover to the heat exchanger. The furnace outlet duct is composed of a space composed of the outer wall of the furnace rear cover, the inner side of the air guide cover, the heat exchanger, the inner side of the collector, and the return air duct. The heat exchanger 44 is arranged inside the furnace outlet duct 43. The air guide cover 431 is arranged outside the furnace 30. The air guide cover 431 is connected to the heat exchanger 44, connecting the furnace rear return air port 33 and the collector 432. One end of the return air duct 433 is connected to the air inlet of the circulation fan 41, and the other end of the return air duct 433 is connected to the air outlet at the rear end center of the furnace body 10. The collector is in the shape of a cone ring, the bottom of the cone faces the heat exchanger, and the inner diameter of the cone mouth is larger than the outer diameter of the return air duct.

[0050] Heat exchanger 44 is fixedly arranged inside furnace body 10, one end of heat exchanger 44 is connected to air guide cover 431 and current collector 432 respectively, and the other end of heat exchanger 44 is connected to furnace air outlet duct 43. Heat exchanger 44 is a finned tube or plate fin type heat exchanger.

[0051] The gas circulation path of the gas circulation cooling system 40 is that the circulating fan 41 blows the low-temperature airflow into between the outer wall of the furnace 30 and the inner wall of the furnace body 10, and the low-temperature airflow bypasses the small heat insulation screen 31 on the side of the furnace 30 and flows into the air inlet 31 on the side of the furnace 30. The high-temperature gas after fully cooling the brazed plate-fin heat exchanger flows out through the rear air outlet 33 of the furnace 30, bypasses the small heat insulation screen 34 at the rear of the furnace 30 and enters the air guide cover 431, then flows through the heat exchanger 44 to be cooled into low-temperature gas, and finally is sucked into the next forced circulation by the circulating fan 41.

[0052] A titanium alloy plate-fin heat exchanger of 300mm (width) × 500mm (length) × 300mm (height) was cooled from a brazing temperature of 920°C to room temperature using the furnace cooling method of traditional vacuum brazing equipment. The time was about 7 hours, the average cooling rate was 128°C / h, and the maximum core-surface temperature difference was 25°C. The temperature-controlled rapid cooling method of the vacuum brazing equipment of this embodiment was used to control the maximum core-surface temperature difference within 50°C. By adjusting the rotation speed of the circulating fan and the gas pressure in the furnace body, the cooling time could be reduced to 2.5 hours, the average cooling rate was 360°C / h, and the cooling efficiency was 2.8 times the original.

Claims

1. A titanium alloy plate-fin heat exchanger vacuum brazing equipment with an air cooling system, characterized in that: The titanium alloy plate-fin heat exchanger vacuum brazing equipment with an air cooling system comprises: A furnace body (10) is used to provide a vacuum environment and accommodate parts to be welded; A vacuum system (20), the vacuum system (20) being connected to the furnace body (10), and the vacuum system being used to discharge gas in the furnace body (10) to obtain a vacuum environment; A furnace liner (30), wherein the furnace liner (30) is arranged in a furnace body (10), wherein a side air inlet (31) and a side small heat insulation screen (32) are arranged in a first direction of the furnace liner (30), and a rear return air inlet (33) and a rear small heat insulation screen (34) are arranged in a second direction of the furnace liner (30), wherein the side air inlet (31) and the rear return air inlet (33) are used to guide airflow in and out of the furnace liner, and the side small heat insulation screen (32) and the rear small heat insulation screen (34) are used to maintain a high temperature state in the furnace liner (30), and wherein the furnace liner (30) is arranged with front and rear openings, and is provided with a furnace liner rear cover (35) and a furnace liner front cover (36); A gas circulation cooling system (40) is connected to the furnace body (10) to form a closed chamber. The gas circulation cooling system (40) comprises a circulation fan (41), a furnace inlet duct (42), a furnace outlet duct (43) and a heat exchanger (44). The circulation fan (41) blows a low-temperature gas through the furnace inlet duct (42) into the space between the furnace (30) and the furnace body (10). The low-temperature gas bypasses the small heat insulation screen (32) on the side of the furnace (30) and flows in from the side air inlet (31) of the furnace (30). The high-temperature gas after fully cooling the brazed plate-fin heat exchanger flows out through the rear air outlet (33) of the furnace (30), bypasses the small heat insulation screen (34) on the rear of the furnace (30) and enters the furnace outlet duct (43). The low-temperature gas flows through the heat exchanger (44) and is cooled to low-temperature gas. The low-temperature gas is sucked into the next forced circulation by the circulation fan (41).

2. The titanium alloy plate-fin heat exchanger vacuum brazing equipment with an air cooling system according to claim 1 is characterized in that: The furnace chamber air inlet duct (42) comprises a front sealing plate (421), a tee (422) and a double air inlet duct (423); the main pipe interface of the tee (422) is connected to the circulation fan (41); the two branch pipe interfaces of the tee (422) are connected to the double air inlet duct (423) so as to introduce the low-temperature airflow of the circulation fan (41) into the furnace body (10) through the tee (422) and the double air inlet duct (423); the two ends of the front sealing plate (421) are respectively connected to the inner wall of the furnace body (10) and the outer wall of the furnace chamber (30); the front sealing plate (421) is used to guide the low-temperature airflow to bypass the small heat insulation screen (32) on the side of the furnace chamber (30) and flow into the air inlet (31) on the side of the furnace chamber (30).

3. The titanium alloy plate-fin heat exchanger vacuum brazing equipment with an air cooling system according to claim 1 is characterized in that: The furnace chamber air outlet duct (43) comprises an air guide cover (431), a collector (432) and a return air duct (433) which are connected in sequence; the heat exchanger (44) is arranged inside the furnace chamber air outlet duct (43); the air guide cover (431) is arranged outside the furnace chamber (30); the air guide cover (431) is connected to the heat exchanger (44) and communicates with the furnace chamber rear return air port (33) and the collector (432); one end of the return air duct (433) is communicated with the air inlet of the circulation fan (41); and the other end of the return air duct (433) is communicated with the air outlet at the rear end center of the furnace body (10).

4. A titanium alloy plate-fin heat exchanger vacuum brazing equipment with an air cooling system according to any one of claims 1 to 3, characterized in that A load thermocouple (50) is arranged in the furnace (30).

5. The titanium alloy plate-fin heat exchanger vacuum brazing equipment with air cooling system according to claim 4 is characterized in that A plurality of load thermocouples (50) are arranged respectively on the surface and the core of the heat exchanger (44). When the temperature difference measured by the load thermocouples (50) is greater than a set value, the rotation speed of the circulation fan (41) is reduced or the gas pressure in the furnace body (10) is reduced, thereby reducing the cooling speed and reducing the temperature difference between the core and the surface of the product.

6. The titanium alloy plate-fin heat exchanger vacuum brazing equipment with an air cooling system according to claim 2 is characterized in that: The direction of the air flow entering the furnace body (10) from the double air inlet duct (423) is parallel to the side wall of the furnace (30) and perpendicular to the rear cover of the furnace (30).

7. The titanium alloy plate-fin heat exchanger vacuum brazing equipment with an air cooling system according to claim 3 is characterized in that: The length of the air guide cover (431) can be adjusted to ensure contact with the furnace rear cover during assembly.

8. The titanium alloy plate-fin heat exchanger vacuum brazing equipment with an air cooling system according to claim 3, characterized in that The collector (432) is in the shape of a cone ring, the bottom of the cone faces the heat exchanger (44), and the inner diameter of the cone mouth is larger than the outer diameter of the return air duct (433).

9. The titanium alloy plate-fin heat exchanger vacuum brazing equipment with air cooling system according to claim 1, characterized in that The vacuum system (20) comprises a vacuum pump (21), a vacuum valve (22) and a pipeline (23); the vacuum pump (21) is connected to the furnace body (10) via the pipeline (23), and a vacuum valve (22) is provided on the pipeline (23).

10. Application of the titanium alloy plate-fin heat exchanger vacuum brazing equipment with air cooling system as claimed in claim 1, characterized in that The titanium alloy plate-fin heat exchanger vacuum brazing equipment is used in the vacuum brazing cooling of large-size titanium alloy plate-fin heat exchangers to achieve a maximum core-surface temperature difference of 50°C, a cooling time of 2 to 3 hours, and an average cooling rate of 350 to 370°C / h.

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