A welded plate heat exchanger

Abstract

The present application relates to the technical field of heat exchange equipment, and in particular to a welded plate heat exchanger, which comprises: a shell, an installation space is formed inside; a welded plate unit, multiple groups are arranged and all are arranged in the installation space, a cold air channel is formed, and two adjacent groups form a hot air channel; a cold air inlet pipe is arranged on the shell and communicated with the air inlet side of the cold air channel; a cold air outlet pipe is arranged on the shell and communicated with the cold air channel for exhaust; a hot air inlet pipe is arranged on the shell and communicated with the air inlet side of the hot air channel; a hot air outlet pipe is arranged on the shell and communicated with the hot air channel for exhaust; a spoiler is formed on the welded plate unit, and one side is convex and the other side is concave. The present application has the effect of increasing the heat exchange efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of heat exchange equipment, and in particular to a welded plate heat exchanger. Background Art

[0002] At present, the welded plate heat exchanger is a highly efficient heat exchange equipment, which is widely used in the heating, cooling and evaporation processes of chemical, petroleum, pharmaceutical, food and other industries. It has the following characteristics: High-efficiency heat exchange: It adopts a sheet structure, and many flow channels are formed between the plates, so that the fluid can flow alternately between the plates many times, thereby achieving efficient heat transfer. Small footprint: Compared with traditional shell and tube heat exchangers, welded plate heat exchangers are small in size and light in weight, and can be arranged more flexibly at the production site. Easy to clean: Because the welded plate heat exchanger has a simple structure, it is easy to disassemble and clean, so it is easier to maintain and maintain for fluids that are prone to scaling and contamination.

[0003] In the prior art, a welded plate heat exchanger generally includes a plurality of groups of heat exchange units, each group of heat exchange units includes two welded plates welded to each other, a longitudinal channel is formed in the middle of the welded plate, two adjacent groups of heat exchange units are welded and fixed, and a transverse channel is formed, hot air flows in the transverse channel, and cold air flows in the longitudinal channel, and the cold air is heated up through heat exchange between the hot air and the cold air, and can be used for other purposes; however, the cold air and the hot air have a short residence time in the channel, and the hot air and the cold air need to repeatedly enter the channel for heat exchange, resulting in poor heat exchange efficiency. Summary of the invention

[0004] In order to increase the heat exchange efficiency, the present application provides a welded plate heat exchanger.

[0005] The present application provides a welded plate heat exchanger, which adopts the following technical solution:

[0006] A welded plate heat exchanger, comprising:

[0007] A housing, forming an installation space inside;

[0008] The welding plate units are arranged in multiple groups and are all arranged in the installation space, forming a cold air channel, and two adjacent groups form a hot air channel;

[0009] A cold air inlet pipe is arranged on the shell and communicated with the air inlet side of the cold air channel;

[0010] A cold air outlet pipe is provided on the shell and is connected to the cold air channel for exhausting air;

[0011] A hot air inlet pipe is arranged on the shell and communicated with the air inlet side of the hot air channel;

[0012] A hot air outlet pipe is provided on the housing and is connected to the hot air channel for exhausting air;

[0013] The spoiler is formed on the welding plate unit, and has a convex side and a concave side.

[0014] By adopting the above technical scheme, hot air passes through the hot air inlet pipe and then flows through the hot air channel and is discharged from the hot air outlet pipe, and cold air passes through the cold air inlet pipe and the cold air channel and is discharged from the cold air outlet pipe, and the hot air passes through the spoiler in the hot air channel to increase the residence time, and exchanges heat with the cold air also in the cold air channel, so that the temperature of the cold air rises; through the setting of the above structure, the heat exchange time of cold air and hot air is extended, thereby increasing the heat exchange efficiency, reducing the number of times cold air and hot air re-enter the channel for heat exchange, and increasing the single heat exchange.

[0015] Optionally, a plurality of support plates are further provided on the welding unit, and the support plates are arranged opposite to each other and support the cold air channel and the hot air channel.

[0016] By adopting the above technical solution, the support plate supports the cold air channel and the hot air channel, reducing the damage to the welding plate unit caused by the pressure difference between the hot air and the cold air. At the same time, the support plate increases the obstruction to the hot air and the cold air, further extending the passage time of the cold air and the hot air. The contact area between the hot air and the cold air is increased by the setting of the support plate and the spoiler, so that the heat of the hot air is transferred to the cold air, thereby increasing the heat exchange efficiency.

[0017] Optionally, a plurality of the spoilers are arranged along a curved path.

[0018] By adopting the above technical solution, the spoiler is bent so that the cold air and hot air flow along a curved path, which increases the time the cold air and hot air stay in the channel, increases the heat exchange time of the hot air and cold air, improves the heat exchange efficiency, and reduces heat loss.

[0019] Optionally, the shell is divided into a preheating zone and an intense heating zone, the preheating zone is close to the cold air inlet pipe; the hot air inlet pipe and the hot air outlet pipe are located on one side, and the hot air inlet pipe is connected to the hot air channel of the intense heating zone, and the hot air outlet pipe is connected to the hot air channel of the preheating zone; the hot air channel of the intense heating zone and the hot air channel of the preheating zone are connected through a guide tube.

[0020] By adopting the above technical scheme, high-temperature hot air enters the hot air channel through the hot air inlet pipe, and exchanges heat with the cold air in the cold air channel. The hot air that has undergone heat exchange exchanges heat with the cold air that has just entered the cold air inlet pipe, so that the cold air enters the strong heating zone after preheating, and rises steadily and gradually, reducing heat loss. The guide tube guides the hot air, so that the strong heating zone and the preheating zone are connected, which is convenient for the circulation of hot air, participates in two heat exchanges, and improves the thermal conductivity efficiency.

[0021] Optionally, a heat recovery mechanism is provided in the air guide tube, and the heat recovery mechanism includes:

[0022] A waste heat air duct is arranged on the shell, one end of which extends to the cold air inlet pipe, and the other end is coiled in the air guide tube and connected to the cold air outlet pipe;

[0023] The air guide plate is arranged on the cold air inlet pipe and is used for guiding the cold air into the waste heat air duct.

[0024] By adopting the above technical scheme, when the hot air enters the guide tube, the air guide plate pours the cold air into the waste heat air duct, the cold air passes through the waste heat air duct to exchange heat with the hot air in the air guide tube, and then returns to the cold air inlet through the waste heat air duct, and then mixes with the cold air and passes through the preheating area and the strong heating area in turn for heat exchange and temperature rise; the set heat recovery mechanism reuses the hot air in the air guide tube, so that heat exchange is still carried out in the air guide tube, reducing the free work of hot air, making full use of the space, and improving the heat exchange efficiency.

[0025] Optionally, a switching component is provided at one end of the waste heat air duct away from the cold air inlet pipe, and the switching component includes:

[0026] A temperature-resistant air duct, arranged on the waste heat air duct and extending to the cold air outlet pipe;

[0027] The switching valve is arranged at the connection between the waste heat air duct and the temperature-resistant air duct, and is used to control the connection between the waste heat air duct and the temperature-resistant air duct or the cold air inlet pipe.

[0028] By adopting the above technical solution, during a specific period of time, the cold air in the waste heat air duct undergoes heat exchange in the air guide tube and its temperature rises. When the cold air at this temperature meets the demand, it can be switched through the switching valve and enter the cold air outlet pipe through the temperature-resistant air duct and be discharged. The switching component is set to reduce the cold air that meets the demand from participating in heating again, reduce ineffective work, reduce heat waste, and improve heat exchange efficiency.

[0029] Optionally, the switching valve is a solenoid valve, and a temperature sensor is provided at one end of the waste heat air duct close to the switching valve, and the temperature sensor is electrically connected to the switching valve.

[0030] By adopting the above technical solution, the temperature of the heat-absorbing cold air in the waste heat air duct is monitored by a temperature sensor. When the use demand is met, the temperature sensor controls the switching of the solenoid valve to connect the waste heat air duct with the temperature-resistant air duct, so that the heated cold air is discharged from the cold air outlet pipe; the set temperature sensor monitors the temperature in real time, so that the temperature of the cold air in the waste heat air duct can be obtained in real time, which is convenient for timely exporting and direct use of the cold air that meets the demand, thereby improving efficiency.

[0031] Optionally, a preheating air duct is coiled inside the hot air outlet pipe, and both ends of the preheating air duct are connected to the cold air inlet pipe.

[0032] By adopting the above technical scheme, the temperature of the hot air in the hot air outlet pipe is relatively low, which can directly participate in the preheating of the cold air, increase the heat exchange time, make full use of the hot air to heat the cold air, and fully absorb and utilize the heat of the hot air within the limited hot air action path.

[0033] Optionally, a high-heat air duct is coiled inside the hot air inlet pipe, one end of the high-heat air duct is connected to the cold air inlet pipe, and the other end is connected to the hot air channel of the strong heating zone.

[0034] By adopting the above technical scheme, the cold air passes through the high-temperature air duct and performs heat exchange in the hot air inlet pipe, making full use of the hot air, and the heated cold air is sent to the strong heat zone again for heating, so that the cold air is fully heated and the hot air is fully utilized, which facilitates the rapid heating of the cold air and improves the heat exchange efficiency.

[0035] Optionally, a heating air duct is coiled inside the cold air outlet pipe, one end of the heating air duct is connected to the hot air inlet pipe, and the other end is connected to the air guide tube.

[0036] By adopting the above technical solution, the hot air in the hot air inlet pipe passes through the heating air duct to heat the cold air outlet pipe. By heating the cold air again, the temperature of the cold air can be increased. The speed of the cold air can be adjusted to shorten the heating time, achieve rapid heat exchange, and improve heat exchange efficiency.

[0037] In summary, this application includes the following beneficial technical effects:

[0038] 1. The hot air passes through the hot air inlet pipe and then flows through the hot air channel and is discharged from the hot air outlet pipe. The cold air passes through the cold air inlet pipe and the cold air channel and is discharged from the cold air outlet pipe. The hot air passes through the spoiler in the hot air channel to increase the retention time and exchanges heat with the cold air in the cold air channel, so that the temperature of the cold air rises. By setting the above structure, the heat exchange time of the cold air and the hot air is extended, thereby increasing the heat exchange efficiency, reducing the number of times the cold air and the hot air enter the channel again for heat exchange, and increasing the single heat exchange.

[0039] 2. When the hot air enters the guide tube, the guide plate pours the cold air into the waste heat air duct. The cold air passes through the waste heat air duct to exchange heat with the hot air in the guide tube, and then passes through the waste heat air duct back to the cold air inlet, and then mixes with the cold air and passes through the preheating area and the strong heating area in turn for heat exchange and temperature increase; the heat recovery mechanism is set to reuse the hot air in the guide tube, so that heat exchange is still carried out in the guide tube, reducing the free work of hot air, making full use of space, and improving heat exchange efficiency;

[0040] 3. Use a temperature sensor to monitor the temperature of the heat-absorbing cold air in the waste heat air duct. When the use demand is met, the temperature sensor controls the solenoid valve to switch, so that the waste heat air duct is connected with the temperature-resistant air duct, so that the heated cold air is discharged from the cold air outlet pipe; the set temperature sensor monitors the temperature in real time, so that the temperature of the cold air in the waste heat air duct is obtained in real time, which is convenient for timely exporting the cold air that meets the demand and directly using it, thereby improving efficiency;

[0041] 4. The hot air in the hot air inlet pipe passes through the heating air duct to heat the cold air outlet pipe. By heating the cold air again, the temperature of the cold air can be increased. The speed of the cold air can be adjusted to shorten the heating time, achieve rapid heat exchange, and improve heat exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the structure of the welded plate heat exchanger in Example 1 of the present application;

[0043] Figure 2 is a cross-sectional view of the housing in Example 1 of the present application;

[0044] Figure 3 This is a schematic structural diagram of the welding plate assembly in Example 1 of the present application;

[0045] Figure 4 This is a schematic diagram of the structure of the heat recovery mechanism in Example 2 of the present application;

[0046] Figure 5 This is a cross-sectional view of the air guide tube in Example 2 of the present application.

[0047] Figure numerals: 100, shell; 110, preheating zone; 120, strong heating zone; 200, welding plate unit; 210, cold air channel; 220, hot air channel; 230, welding plate combination; 231, special-shaped plate; 310, cold air inlet pipe; 320, cold air outlet pipe; 330, hot air inlet pipe; 340, hot air outlet pipe; 400, spoiler; 500, support plate; 600, air guide tube; 700, heat recovery mechanism; 710, waste heat air duct; 720, air guide plate; 730, switching component; 731, temperature-resistant air duct; 732, switching valve; 733, temperature sensor; 740, preheating air duct; 750, high-temperature air duct; 760, heating air duct; 770, heat exchange valve; 780, return air duct. DETAILED DESCRIPTION

[0048] The following is combined with Figure 1-Figure 5 This application is described in further detail.

[0049] An embodiment of the present application discloses a welded plate heat exchanger. Example

[0050] refer to Figure 1 and Figure 2 The welding plate heat exchanger comprises a shell 100, a plurality of welding plate units 200 arranged in the shell 100, a cold air inlet pipe 310 arranged on the shell 100, a cold air outlet pipe 320 arranged on the shell 100, a hot air inlet pipe 330 arranged on the shell 100, a hot air outlet pipe 340 arranged on the shell 100, and a spoiler 400 arranged in the welding plate unit 200 for increasing the spoiler of hot air and cold air. An installation space is formed in the shell 100, and the welding plate unit 200 is arranged in the installation space and has a cold air vent formed therein. The cold air inlet pipe 310 and the cold air outlet pipe 320 are both connected to the cold air channel 210, and the hot air inlet pipe 330 and the hot air outlet pipe 340 are both connected to the hot air channel 220. Heat is conducted between the hot air channel 220 and the cold air channel 210. When the hot air enters the hot air channel 220 through the hot air inlet pipe 330, the cold air enters the cold air channel 210 through the cold air inlet pipe 310. The hot air exchanges heat with the cold air, and then the cold air is discharged through the cold air outlet pipe 320, and the hot air is discharged through the hot air outlet pipe 340.

[0051] refer to Figure 1 , Figure 2 and Figure 3 The welding plate unit 200 includes two groups of welding plate assemblies 230, each group of welding plate assemblies 230 includes two special-shaped plates 231, the two ends of the two special-shaped plates 231 are close to each other and welded and fixed, a groove is opened in the middle of the two special-shaped plates 231, and the two grooves are far away from each other, the cross-sectional area of ​​the middle of the two special-shaped plates 231 is larger than the cross-sectional area of ​​the edge, and the cross-section of the two special-shaped plates 231 after welding and fixing is diamond-shaped and forms a cold air channel 210; two adjacent groups of welding plate assemblies 230 abut against each other, the abutting point is the unwelded part of the special-shaped plate 231, and the special-shaped plate 231 at this point bulges outward in the direction away from the cold air channel 210, and is welded with the special-shaped plate 231 of the adjacent welding plate assembly 230 to form a hot air channel 220, the axis of the cold air channel 210 and the hot air channel 220 are perpendicular, and the special-shaped plate 231 is made of stainless steel heat-conducting material, which is convenient for heat exchange between hot air and cold air.

[0052] There are multiple groups of spoilers 400, which are fixedly connected to the special-shaped plate 231, and one side of the spoiler 400 is convex and the other side is concave to form an uneven surface. Multiple spoilers 400 are arranged at equal intervals on the special-shaped plate 231 according to a curved path to form a walking route for cold air or hot air. The curved path can be a regular normally distributed curve or broken line; in order to enhance the stability of the cold air channel 210 and the hot air channel 220, multiple support plates 500 are fixedly connected to the special-shaped plate 231, and the number of support plates 500 is less than the number of spoilers 400. One side of the support plate 500 is convex and the other side is concave, and the protrusion height is greater than the protrusion height of the spoiler 400, and it abuts against the support plate 500 on the corresponding special-shaped plate 231. Multiple support plates 500 on the same special-shaped plate 231 are arranged at intervals, and the protrusion directions of adjacent support plates 500 are opposite.

[0053] The shell 100 is divided into a preheating zone 110 and an intense heating zone 120. The hot air channels 220 in the preheating zone 110 and the intense heating zone 120 are parallel to each other. An air guide 600 is fixedly connected to the shell 100, and the air guide 600 connects the hot air channels 220 in the preheating zone 110 and the intense heating zone 120. A cold air inlet pipe 310 is fixedly connected to a side of the shell 100 close to the preheating zone 110, and the cold air inlet pipe 310 is connected to a plurality of cold air channels 210. The cold air outlet pipe 320 is located at a side of the shell 100 away from the cold air inlet. At one end of the tube 310, the cold air outlet pipe 320 is connected to multiple cold air channels 210 and is located on the side of the intense heating zone 120; the hot air inlet pipe 330 is fixedly connected to the shell 100, and the hot air inlet pipe 330 is located on the side of the shell 100 away from the air guide tube 600, and the hot air inlet pipe 330 is connected to multiple hot air channels 220 of the intense heating zone 120; the hot air outlet pipe 340 is fixedly connected to the side of the shell 100 away from the air guide tube 600, and the hot air outlet pipe 340 is connected to multiple hot air channels 220 of the preheating zone 110.

[0054] The implementation principle of Example 1 of the present application is as follows: when heat exchange is performed, cold air passes through the cold air inlet pipe 310, through the cold air channel 210, and then is discharged from the cold air outlet pipe 320; hot air passes through the hot air inlet pipe 330, through the hot air channel 220, and then is discharged from the hot air outlet pipe 340; the hot air passes through the spoiler 400 and the support plate 500 in the hot air channel 220, so that the hot air flows along a predetermined path; at the same time, the cold air passes through the spoiler 400 and the support plate 500 in the cold air channel 210, and flows along a predetermined route; the hot air and the cold air complete the heat exchange through heat conduction between the special-shaped plates 231; the hot air temperature drops, and the cold air temperature rises; after several cycles, the heat exchange work is completed. Example

[0055] refer to Figure 4 and Figure 5The difference between this embodiment and embodiment 1 is that a heat recovery mechanism 700 is provided in the air guide tube 600, and the heat recovery mechanism 700 includes an air guide plate 720 fixedly connected to the inner wall of the cold air inlet pipe 310, and the air guide plate 720 extends from the inlet of the cold air inlet pipe 310 to the edge of the cold air channel 210. A plurality of waste heat air ducts 710 are fixedly connected between the air guide plate 720 and the side wall of the cold air inlet pipe 310, and the other end of the waste heat air duct 710 is coiled in the air guide tube 600 to absorb the heat of the hot air, so that the cold air in the waste heat air duct 710 becomes hot; after being coiled, the waste heat air duct 710 returns to the cold air inlet pipe 310 again and merges with the cold air to enter the cold air channel 210.

[0056] In order to converge and utilize the cold air in the waste heat air duct 710, a switching component 730 is provided on the waste heat air duct 710, and the switching component 730 includes a switching valve 732, the switching valve 732 is fixedly connected to the waste heat air duct 710, and a temperature-resistant air duct 731 is bypass-connected through the switching valve 732, the temperature-resistant air duct 731 extends to the cold air outlet pipe 320 and is connected to the cold air outlet pipe 320, and the switching valve 732 is a three-way valve and a solenoid valve; in order to further facilitate the control of the switching of the switching valve 732, a temperature sensor 733 is fixedly connected to one end of the waste heat air duct 710 close to the switching valve 732, and the temperature sensor 733 is used to monitor the temperature in the waste heat air duct 710, and the temperature sensor 733 is electrically connected to the switching valve 732 and is used to control the passage switching of the switching valve 732.

[0057] A preheating duct 740 is arranged in a spiral shape inside the hot air outlet duct 340. The preheating duct 740 is arranged spirally along the inner wall of the hot air outlet duct 340. One end of the preheating duct 740 is connected to the cold air inlet duct 310 and is located on the side of the cold air inlet duct 310 away from the waste heat duct 710. The other end of the preheating duct 740 is connected to a heat exchange valve 770. The heat exchange valve 770 is a three-way valve. One passage of the heat exchange valve 770 is connected to a return pipe. The return pipe It is connected to the cold air inlet pipe 310; another passage of the heat exchange valve 770 is fixedly connected to a high-temperature air duct 750, which is spirally coiled in the hot air inlet pipe 330 and fits against the inner wall of the hot air inlet pipe 330. One end of the high-temperature air duct 750 away from the heat exchange valve 770 extends to the cold air outlet pipe 320. In other embodiments, one end of the high-temperature air duct 750 away from the heat exchange valve 770 extends to the cold air channel 210 in the high heat zone.

[0058] In order to heat the cold air at the cold air outlet pipe 320 again, a heating air duct 760 is spirally arranged inside the cold air outlet pipe 320. One end of the heating air duct 760 is connected to the hot air inlet pipe 330, and the other end of the heating air duct 760 is connected to the air guide tube 600. The hot air can pass through the hot air inlet pipe 330 and the heating air duct 760 to heat the cold air, and then enter the air guide tube 600 through the heating air duct 760.

[0059] The implementation principle of Example 2 of the present application is as follows: when heat exchange is performed, cold air passes through the cold air inlet pipe 310, through the cold air channel 210, and then is discharged from the cold air outlet pipe 320; hot air passes through the hot air inlet pipe 330, through the hot air channel 220, and then is discharged from the hot air outlet pipe 340; the hot air passes through the spoiler 400 and the support plate 500 in the hot air channel 220, so that the hot air flows along a predetermined path; at the same time, the cold air passes through the spoiler 400 and the support plate 500 in the cold air channel 210, and flows along a predetermined route; the hot air and the cold air complete the heat exchange through heat conduction between the special-shaped plates 231.

[0060] At the same time, part of the cold air enters the air guide tube 600 through the waste heat air duct 710 for heat exchange, and then is monitored by the temperature sensor 733 to see whether it meets the temperature standard, and controls the switching of the switching valve 732. When the temperature meets the standard and can meet the supply and demand, the switching valve 732 switches the waste heat air duct 710 to be connected with the temperature-resistant air duct 731, so that the cold air absorbs heat and is discharged through the cold air outlet pipe 320.

[0061] At the same time, part of the cold air is preliminarily preheated in the hot air outlet pipe 340 through the preheating air duct 740. The temperature of the hot air in the hot air outlet pipe 340 is lower than the temperature of the hot air in other parts, so that the cold air is not hot enough. The passage of the heat exchange valve 770 can be switched according to customer needs. When the required air temperature is not high, the preheating air duct 740 can be connected to the high-temperature air duct 750. After absorbing heat at the hot air inlet pipe 330, it enters the cold air channel 210 and is heated again in the strong heat zone 120, and then discharged from the cold air outlet pipe 320.

[0062] In order to fully heat the cold air, part of the hot air in the hot air inlet pipe 330 passes through the heating air duct 760 to heat the cold air in the cold air outlet pipe 320 again, so that the temperature of the discharged cold air rises again, and the hot air involved in the heating flows into the preheating zone 110 again through the air guide tube 600, thereby realizing full utilization of the hot air.

[0063] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A welded plate heat exchanger, characterized in that: include: A housing (100) having an installation space formed therein; A plurality of welding plate units (200) are provided and all are arranged in the installation space, forming a cold air channel (210), and two adjacent groups form a hot air channel (220); A cold air inlet pipe (310) is arranged on the housing (100) and is in communication with the air inlet side of the cold air channel (210); A cold air outlet pipe (320) is arranged on the housing (100) and is connected to the cold air channel (210) for exhausting air; A hot air inlet pipe (330) is arranged on the housing (100) and is in communication with the air inlet side of the hot air channel (220); A hot air outlet pipe (340) is disposed on the housing (100) and is connected to the hot air channel (220) for exhausting air; A spoiler (400) is formed on the welding plate unit (200) and has a convex side and a concave side; The shell (100) is divided into a preheating zone (110) and an intense heating zone (120), the preheating zone (110) being close to the cold air inlet pipe (310); the hot air inlet pipe (330) and the hot air outlet pipe (340) being located on one side, and the hot air inlet pipe (330) being in communication with the hot air channel (220) of the intense heating zone (120), and the hot air outlet pipe (340) being in communication with the hot air channel (220) of the preheating zone (110); the hot air channel (220) of the intense heating zone (120) and the hot air channel (220) of the preheating zone (110) being in communication via an air guide tube (600); A heat recovery mechanism (700) is provided in the air guide cylinder (600), and the heat recovery mechanism (700) comprises: A waste heat air duct (710) is arranged on the housing (100), one end of which extends to the cold air inlet duct (310), and the other end of which is coiled in the air guide tube (600) and connected to the cold air outlet duct (320); an air guide plate (720), arranged on the cold air inlet pipe (310), and used for guiding the cold air into the waste heat air pipe (710); A switching component (730) is provided at one end of the waste heat air duct (710) away from the cold air inlet duct (310), and the switching component (730) comprises: a temperature-resistant air duct (731), arranged on the waste heat air duct (710) and extending to the cold air outlet duct (320); The switching valve (732) is arranged at the connection between the waste heat air duct (710) and the temperature-resistant air duct (731), and is used to control the communication between the waste heat air duct (710) and the temperature-resistant air duct (731) or the cold air inlet duct (310).

2. The welded plate heat exchanger according to claim 1, characterized in that: A plurality of support plates (500) are also provided on the welding plate unit (200); the support plates (500) are arranged opposite to each other and support the cold air channel (210) and the hot air channel (220).

3. The welded plate heat exchanger according to claim 1, characterized in that: The plurality of spoilers (400) are arranged in a curved path.

4. The welded plate heat exchanger according to claim 1, characterized in that: The switching valve (732) is a solenoid valve, and a temperature sensor (733) is provided at one end of the waste heat air duct (710) close to the switching valve (732), and the temperature sensor (733) is electrically connected to the switching valve (732).

5. The welded plate heat exchanger according to claim 1, characterized in that: A preheating air duct (740) is arranged in a coiled manner inside the hot air outlet duct (340), and both ends of the preheating air duct (740) are connected to the cold air inlet duct (310).

6. The welded plate heat exchanger according to claim 1, characterized in that: A high-temperature air duct (750) is arranged in a coiled manner inside the hot air inlet duct (330); one end of the high-temperature air duct (750) is connected to the cold air inlet duct (310), and the other end is connected to the hot air channel (220) of the strong heating zone (120).

7. The welded plate heat exchanger according to claim 1, characterized in that: A heating air duct (760) is coiled inside the cold air outlet duct (320); one end of the heating air duct (760) is connected to the hot air inlet duct (330), and the other end is connected to the air guide tube (600).

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