Combined high-temperature gas-gas heat exchanger and method

Abstract

The combined high-temperature gas-gas heat exchanger comprises a heat exchange shell, an air inlet pipe and an air outlet pipe which communicate with the interior of the heat exchange shell are arranged at the two ends of the top face of the heat exchange shell correspondingly, and a smoke inlet and a smoke outlet are formed in the end faces of the left side and the right side of the heat exchange shell correspondingly; the tubular heat exchange module is arranged in the heat exchange shell on the flue gas inlet side; the plate type heat exchange module is arranged in the heat exchange shell on the flue gas outlet side; the air flow channel comprises a tubular heat exchange module and a plate type heat exchange module, and the air flow channel communicates with the air inlet pipe and the air outlet pipe; the invention further discloses a control method. The device has the beneficial effects that the tubular heat exchanger and the plate heat exchanger are combined, and the advantages of the tubular heat exchanger and the plate heat exchanger are combined, so that the device can bear high temperature and high pressure and can provide efficient heat exchange.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchangers, and particularly to a combined high-temperature gas-gas heat exchanger and method. Background Art

[0002] In the metallurgical industry, the flue gas temperature of hot rolling heating furnaces generally exceeds 600 °C, and even the flue gas temperature at the outlet of some heating furnaces will exceed 900 °C. How to efficiently recover the waste heat of flue gas is the common goal of the metallurgical industry.

[0003] Heat exchangers play an important role in the recovery of waste heat from flue gas, and are used to transfer heat from one fluid to another. Currently, the flue gas waste heat recovery heat exchangers used in hot rolling heating furnaces in the metallurgical industry are mainly tubular heat exchangers. Among many types of heat exchangers, shell-and-tube heat exchangers and plate heat exchangers are two of the most basic types.

[0004] Advantages and disadvantages of existing heat exchangers:

[0005] 1. Shell-and-tube heat exchanger

[0006] The shell-and-tube heat exchanger has the following advantages:

[0007] Simple structure, relatively easy manufacturing process, and low cost. Stable operation, can be used to handle high-temperature, high-pressure and high-flow-rate fluids. Due to the characteristics of the structure, it can withstand a certain axial and radial unbalanced force, reducing the vibration and deformation of the equipment.

[0008] However, the shell-and-tube heat exchanger also has the following disadvantages:

[0009] Since the heat transfer surface is fixed on the tube sheet and cannot be mechanically cleaned, when the tubes are blocked, the heat exchanger needs to be disassembled for cleaning. For high-temperature, high-pressure and high-flow-rate fluids, the sealing gaskets of the shell-and-tube heat exchanger are easily damaged and need to be frequently replaced. The shell-and-tube heat exchanger has a large volume and requires a large installation space. Most importantly, the shell-and-tube heat exchanger has a lower heat transfer efficiency compared to the plate heat exchanger.

[0010] 2. Plate heat exchanger

[0011] The plate heat exchanger has the following advantages:

[0012] High heat transfer coefficient: The flow channels of the plate heat exchanger are small, and the cross-section of the plate is complex in shape, causing the flow direction and velocity of the fluid to change continuously, increasing the fluid disturbance. Therefore, turbulent flow can be achieved at a very low flow velocity, resulting in a high heat transfer coefficient. The heat transfer efficiency can reach 85% - 90%. Strong adaptability: The required heat transfer area can be achieved by increasing or decreasing the number of plates. Flexible assembly. Compact structure, small volume, and less material consumption: The heat transfer area per cubic meter can reach 250 square meters, and only about 15 kilograms of metal is required per square meter of heat transfer surface. Small fouling coefficient: Due to the large flow disturbance, dirt is not easily deposited; the materials used for the plates are of good quality, with little corrosion and a small fouling coefficient value.

[0013] However, the plate heat exchanger also has the following deficiencies:

[0014] Due to the structural characteristics of the plate heat exchanger, its ability to withstand thermal pressure is limited, and it is not suitable for the heat exchange application environment of ultra-high temperature (higher than 800 °C) fluids, and it is prone to fracture and deformation at high temperatures. Currently, the application of plate heat exchangers in high-temperature fluid heat exchange is relatively rare. However, with the continuous development of the industrial field, the demand for waste heat recovery and utilization technology in high-temperature environments is urgent, and higher requirements are also put forward for the performance and stability of heat exchangers, and technological innovation and product innovation are urgently needed.

[0015] In order to improve the utilization rate of waste heat recovery in high-temperature environments, we propose a solution for high-temperature plate heat exchangers. By using advanced materials and technologies, the traditional plate heat exchanger is improved and optimized. At the same time, this method also adopts advanced heat transfer technologies and optimized designs to improve the heat transfer efficiency of the heat exchanger, resulting in a significant increase in the utilization rate of waste heat recovery. It can achieve efficient and stable heat exchange in high-temperature environments.

[0016] Therefore, we propose a combined high-temperature gas-gas heat exchanger and method. Summary of the Invention

[0017] In view of the above deficiencies of the prior art, the present invention provides a combined high-temperature gas-gas heat exchanger and method.

[0018] To achieve the above invention purpose, the technical solution adopted by the present invention is as follows:

[0019] A combined high-temperature gas-gas heat exchanger includes a heat exchange housing. At both ends of the top surface of the heat exchange housing, an air inlet pipe and an air outlet pipe communicating with the inside of the heat exchange housing are respectively provided. On the left and right side end faces of the heat exchange housing, a flue gas inlet and a flue gas outlet are respectively opened; a tubular heat exchange module is arranged in the heat exchange housing on the flue gas inlet side; a plate heat exchange module is arranged in the heat exchange housing on the flue gas outlet side; an air flow channel includes the tubular heat exchange module and the plate heat exchange module, the air flow channel communicates the air inlet pipe and the air outlet pipe, and the air flow channel is arranged in a serpentine shape.

[0020] By arranging a tubular heat exchange module and a plate heat exchange module inside a heat exchange housing, an air inlet pipe and an air outlet pipe are arranged at the top of the heat exchange housing, and an air flow channel is arranged inside the heat exchange housing. The left and right sides of the heat exchange housing are set as openings to serve as a flue gas inlet and a flue gas outlet. During use, the flue gas horizontally enters the heat exchange housing from the flue gas inlet, the air vertically enters the air flow channel from the air inlet pipe. The air flows through the interiors of the plate heat exchange module and the tubular heat exchange module and then is discharged from the air outlet pipe. The flue gas also flows horizontally through the exteriors of the tubular heat exchange module and the plate heat exchange module and then is discharged from the flue gas outlet, realizing the internal and external air-air heat exchange. By combining the tubular heat exchange module and the plate heat exchange module, and arranging the tubular heat exchange module at the flue gas inlet, the high-temperature flue gas can be heat-exchanged first to reduce the temperature of the flue gas. The flue gas after being cooled by one-time heat exchange is then more efficiently heat-exchanged through the plate heat exchange module. At the same time, the advantages of the tubular heat exchange module and the plate heat exchange module are utilized, the heat exchange efficiency is improved, and the stability is better.

[0021] Further defined, the tubular heat exchange module includes a first tubular heat exchanger and a second tubular heat exchanger, the plate heat exchange module includes a first plate heat exchanger and a second plate heat exchanger, and the air flow channel further includes a first elbow, a second elbow, and a third elbow; from the flue gas inlet to the flue gas outlet direction are successively the first tubular heat exchanger, the second tubular heat exchanger, the first plate heat exchanger, and the second plate heat exchanger. The air outlet pipe is communicated with the top of the first tubular heat exchanger. The first elbow communicates the bottom of the first tubular heat exchanger and the bottom of the second tubular heat exchanger. The third elbow communicates the top of the second tubular heat exchanger and the top of the first plate heat exchanger. The second elbow communicates the bottom of the first plate heat exchanger and the bottom of the second plate heat exchanger. The top of the second plate heat exchanger is communicated with the air inlet pipe.

[0022] By arranging the first tubular heat exchanger, the second tubular heat exchanger, the first plate heat exchanger, and the second plate heat exchanger, a four-pass heat exchange structure is formed, making full use of the characteristics of the tubular heat exchanger and the plate heat exchanger. The first tubular heat exchanger at the flue gas inlet bears the flue gas scouring and thermal stress expansion, and then the subsequent first plate heat exchanger and second plate heat exchanger realize higher-efficiency heat exchange. The four-pass arrangement can make the flue gas heat exchange time longer, the heat exchange effect better, and improve the flue gas recovery utilization rate.

[0023] Further defined, the first tubular heat exchanger includes a number of columns of arc-shaped heat pipes, and the second tubular heat exchanger includes a number of straight heat pipes. The number of columns of arc-shaped heat pipes and the number of columns of straight heat pipes are both arranged at intervals in the front-back direction of the heat exchange housing. The bending directions of two adjacent columns of arc-shaped heat pipes are arranged in opposite directions. Sealing plates are provided at the top and bottom of the arc-shaped heat pipes and the straight heat pipes. The top of the arc-shaped heat pipe passes through the sealing plate and is connected to the air outlet pipe, and the bottom also passes through the sealing plate and is connected to the first elbow. The top of the straight heat pipe passes through the sealing plate and is connected to the third elbow, and the bottom also passes through the sealing plate and is connected to the first elbow. By setting the heat pipes of the first tubular heat exchanger as arc-shaped heat pipes, the flue gas scouring resistance of the first tubular heat exchanger can be stronger, and the performance of bearing thermal stress expansion is also better, making the device more stable during use.

[0024] Further defined, an air bypass connecting the third elbow is provided on the air inlet pipe, and a bypass regulating valve is provided on the air bypass. Setting an air bypass and a bypass regulating valve can open the bypass regulating valve when the pressure in the air flow channel is too high or the temperature in the air flow channel is too high, reduce the pressure in the air flow channel and the air waste heat temperature, reduce the air pressure resistance, and protect the air pipeline equipment at the back end.

[0025] Further defined, both the first plate heat exchanger and the second plate heat exchanger include a number of heat exchange plates. The number of heat exchange plates are arranged at intervals in the front-back direction of the heat exchange housing. A fluid cavity is provided in each heat exchange plate. The top of the fluid cavity in the first plate heat exchanger is connected to the third elbow, and the bottom is connected to the second elbow. The top of the fluid cavity in the second plate heat exchanger is connected to the air inlet pipe, and the bottom is connected to the second elbow. By providing a fluid cavity in the heat exchange plate, air passes through the fluid cavity in the heat exchange plate, and flue gas passes through the gap between adjacent heat exchange plates to achieve heat exchange. The structure is simple and easy to manufacture.

[0026] Further defined, leak-proof ridges are convexly provided on the outside of the top and bottom of the heat exchange plate, and a number of pits and a number of protrusions are provided on the plate surface of the heat exchange plate. By providing leak-proof ridges at the top and bottom of the heat exchange plate, when adjacent heat exchange plates are installed, the leak-proof ridges are in close contact with each other, forming a gap for flue gas to pass between the heat exchange plate surfaces, and can also seal the air to prevent air from leaking from between adjacent heat exchange plates to the outside of the heat exchange plate. The pits and protrusions on the plate surface can cause different vortex disturbances to the flue gas. The vortex disturbances can accelerate the heat exchange speed, strengthen the heat transfer effect, and also increase the heat exchange area, further enhancing the heat exchange effect.

[0027] Further defined, it also includes a pressure sensor, a temperature sensor and a controller. The bypass regulating valve is an electrically controlled valve. The bypass regulating valve, the pressure sensor and the temperature sensor are all electrically connected to the controller. The pressure sensor is arranged in the air inlet pipe and the air outlet pipe to detect the gas pressure in the air flow channel. The temperature sensor is arranged in the air outlet pipe to detect the temperature in the air outlet pipe. By setting the pressure sensor, the temperature sensor and the controller, the automation degree of the on-off of the bypass regulating valve is higher and the pressure regulation is more accurate.

[0028] A control method using a combined high-temperature gas-gas heat exchanger is as follows:

[0029] S1: Preset the pressure threshold P in the air inlet pipe and the temperature threshold T in the air outlet pipe in advance;

[0030] S2: During use, the real-time detection value of the gas pressure in the air inlet pipe by the pressure sensor is P1, and the real-time detection value of the gas temperature in the air outlet pipe by the temperature sensor is T1;

[0031] S3: When P1 ≥ P or T1 ≥ T, the controller controls the bypass regulating valve to open. When P1 < P and T1 < T, the controller controls the bypass regulating valve to close.

[0032] The beneficial effect of the present invention is that by combining the tubular heat exchanger and the plate heat exchanger, the advantages of the tubular heat exchanger and the plate heat exchanger are combined, so that the device can not only withstand high temperature and high pressure but also provide efficient heat exchange. Brief Description of the Drawings

[0033] Figure 1 Is a three-dimensional schematic diagram of the present invention;

[0034] Figure 2 Is a front view of the present invention with the front side plate removed;

[0035] Figure 3 Is a partial connection schematic diagram between adjacent heat exchange plates;

[0036] Figure 4 Is a three-dimensional schematic diagram of the heat exchange plate;

[0037] Figure 5 Schematic diagram of the connection of electrical components.

[0038] The symbols of each component are as follows:

[0039] Heat exchange housing 1, pressure sensor 2, temperature sensor 21, controller 3, air inlet pipe 4, air outlet pipe 5, flue gas inlet 6, flue gas outlet 7, first tubular heat exchanger 8, arc-shaped heat pipe 81, second tubular heat exchanger 9, straight heat pipe 91, first plate heat exchanger 10, second plate heat exchanger 11, first elbow 12, third elbow 13, second elbow 14, heat exchange plate 15, leak-proof rib 151, pit 152, protrusion 153, air bypass 16, bypass regulating valve 17. Specific embodiments

[0040] The specific embodiments of the present invention will be described below to facilitate those skilled in the art of the present technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art of the present technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions created using the concept of the present invention are within the scope of protection.

[0041] Example:

[0042] As Figures 1 - 5As shown in the figure, a combined high-temperature gas-gas heat exchanger includes a heat exchange housing 1, a tubular heat exchange module, a plate heat exchange module, an air flow channel, a pressure sensor 2, a temperature sensor 21, and a controller 3. At both ends of the top surface of the heat exchange housing 1, an air inlet pipe 4 and an air outlet pipe 5 communicating with the inside of the heat exchange housing 1 are respectively provided. At the left and right side end faces of the heat exchange housing 1, a flue gas inlet 6 and a flue gas outlet 7 are respectively opened; the tubular heat exchange module is arranged in the heat exchange housing 1 on the side of the flue gas inlet 6, and the plate heat exchange module is arranged in the heat exchange housing 1 on the side of the flue gas outlet 7; the tubular heat exchange module includes a first tubular heat exchanger 8 and a second tubular heat exchanger 9, the plate heat exchange module includes a first plate heat exchanger 10 and a second plate heat exchanger 11, and the air flow channel includes a first elbow 12, a second elbow 14, and a third elbow 13; in the direction from the flue gas inlet 6 to the flue gas outlet 7, there are successively a first tubular heat exchanger 8, a second tubular heat exchanger 9, a first plate heat exchanger 10, and a second plate heat exchanger 11. The air outlet pipe 5 is communicated with the top of the first tubular heat exchanger 8. The first elbow 12 communicates the bottom of the first tubular heat exchanger 8 and the bottom of the second tubular heat exchanger 9. The third elbow 13 communicates the top of the second tubular heat exchanger 9 and the top of the first plate heat exchanger 10. The second elbow 14 communicates the bottom of the first plate heat exchanger 10 and the bottom of the second plate heat exchanger 11. The top of the second plate heat exchanger 11 is communicated with the air inlet pipe 4; the air flow channel communicates the air inlet pipe 4 and the air outlet pipe 5, and the air flow channel is arranged in a serpentine bend. The first tubular heat exchanger 8, the first elbow 12, the second tubular heat exchanger 9, the third elbow 13, the first plate heat exchanger 10, the second elbow 14, and the second plate heat exchanger 11 are interconnected to form a serpentine air flow channel; the first tubular heat exchanger 8 includes a plurality of rows of arc-shaped heat pipes 81, the second tubular heat exchanger 9 includes a plurality of straight heat pipes 91, and a plurality of rows of arc-shaped heat pipes 81 and a plurality of rows of straight heat pipes 91 are both arranged at intervals in the front-back direction of the heat exchange housing 1. The bending directions of adjacent two rows of arc-shaped heat pipes 81 are opposite. Sealing plates are provided at the top and bottom of the arc-shaped heat pipes 81 and the straight heat pipes 91. The top of the arc-shaped heat pipe 81 passes through the sealing plate and is communicated with the air outlet pipe 5, and the bottom also passes through the sealing plate and is communicated with the first elbow 12. The top of the straight heat pipe 91 passes through the sealing plate and is communicated with the third elbow 13, and the bottom also passes through the sealing plate and is communicated with the first elbow 12; both the first plate heat exchanger 10 and the second plate heat exchanger 11 include a plurality of heat exchange plates 15, and a plurality of heat exchange plates 15 are arranged at intervals in the front-back direction of the heat exchange housing 1. A fluid cavity is provided in each heat exchange plate 15. The top of the fluid cavity in the first plate heat exchanger 10 is communicated with the third elbow 13, and the bottom is communicated with the second elbow 14. The top of the fluid cavity in the second plate heat exchanger 11 is communicated with the air inlet pipe 4, and the bottom is communicated with the second elbow 14; leak-proof ridges 151 are convexly provided on the outside of the top and bottom of the heat exchange plate 15, and a plurality of pits 152 and a plurality of protrusions 153 are provided on the surface of the heat exchange plate 15;An air bypass 16 communicating with the third elbow 13 is provided on the air inlet pipe 4, and a bypass regulating valve 17 is provided on the air bypass 16; the bypass regulating valve 17 is an electric control valve, and the bypass regulating valve 17, the pressure sensor 2 and the temperature sensor 21 are all electrically connected to the controller 3. The pressure sensor 2 is arranged in the air inlet pipe 4 and the air outlet pipe 5 to detect the gas pressure in the air flow passage, and the temperature sensor 21 is arranged in the air outlet pipe 5 to detect the temperature in the air outlet pipe 5.

[0043] By arranging a tubular heat exchange module and a plate heat exchange module in the heat exchange housing 1, arranging an air inlet pipe 4 and an air outlet pipe 5 at the top of the heat exchange housing 1, and arranging an air flow passage inside the heat exchange housing 1, the left and right sides of the heat exchange housing 1 are set as openings to serve as a flue gas inlet 6 and a flue gas outlet 7. During use, the flue gas horizontally enters the heat exchange housing 1 from the flue gas inlet 6, the air vertically enters the air flow passage from the air inlet pipe 4, the air flows through the inside of the plate heat exchange module and the tubular heat exchange module and then is discharged from the air outlet pipe 5, and the flue gas also horizontally flows through the outside of the tubular heat exchange module and the plate heat exchange module and then is discharged from the flue gas outlet 7, realizing the gas-gas heat exchange inside and outside. By combining the tubular heat exchange module and the plate heat exchange module, and arranging the tubular heat exchange module at the flue gas inlet 6, the high-temperature flue gas can be heat-exchanged first to reduce the temperature of the flue gas. The flue gas after being heat-exchanged and cooled once is then more efficiently heat-exchanged through the plate heat exchange module. At the same time, the advantages of the tubular heat exchange module and the plate heat exchange module are utilized, the heat exchange efficiency is improved, and the stability is better.

[0044] By setting the first tubular heat exchanger 8, the second tubular heat exchanger 9, the first plate heat exchanger 10 and the second plate heat exchanger 11, a four-pass heat exchange structure is formed, making full use of the characteristics of the tubular heat exchanger and the plate heat exchanger. The first tubular heat exchanger 8 at the flue gas inlet 6 bears the flue gas scouring and thermal stress expansion, and then the subsequent first plate heat exchanger 10 and the second plate heat exchanger 11 achieve higher-efficiency heat exchange. The four-pass setting can make the flue gas heat exchange time longer and the heat exchange effect better, improving the flue gas recovery utilization rate; by setting the heat pipes of the first tubular heat exchanger 8 as arc-shaped heat pipes 81, the flue gas scouring resistance of the first tubular heat exchanger 8 can be stronger, and the performance of bearing thermal stress expansion is also better, making the device more stable during use; setting an air bypass 16 and a bypass regulating valve 17 can open the bypass regulating valve 17 when the pressure in the air flow channel is too high or the temperature in the air flow channel is too high, reducing the pressure in the air flow channel and the air waste heat temperature, reducing the air pressure resistance, and protecting the air rear-end pipeline equipment; a fluid cavity is arranged in the heat exchange plate 15, air passes through the fluid cavity in the heat exchange plate 15, and flue gas passes through the gap between adjacent heat exchange plates 15 to achieve heat exchange. The structure is simple and easy to manufacture; anti-leakage ribs 151 are arranged at the top and bottom of the heat exchange plate 15. When adjacent heat exchange plates 15 are installed, the anti-leakage ribs 151 are in close contact with each other, forming a gap for the flue gas to pass between the heat exchange plate 15 surfaces, and can also seal the air to prevent the air from leaking from between adjacent heat exchange plates 15 to the outside of the heat exchange plate 15. The pits 152 and protrusions 153 on the plate surface can make the flue gas form different vortex disturbances. The vortex disturbances can accelerate the heat exchange speed, strengthen the heat transfer effect, and can also increase the heat exchange area, further enhancing the heat exchange effect; by setting a pressure sensor 2, a temperature sensor 21 and a controller 3, the on-off automation degree of the bypass regulating valve 17 is higher and the pressure regulation is more accurate.

[0045] A control method, using a combined high-temperature gas-gas heat exchanger, the steps are as follows:

[0046] S1: Preset the pressure threshold P in the air inlet pipe 4 and the temperature threshold T in the air outlet pipe 5;

[0047] S2: During use, the real-time detected value of the gas pressure in the air inlet pipe 4 by the pressure sensor 2 is P1, and the real-time detected value of the gas temperature in the air outlet pipe 5 by the temperature sensor 21 is T1;

[0048] S3: When P1≥P or T1≥T, the controller 3 controls the bypass regulating valve 17 to open, and when P1<P and T1<T, the controller 3 controls the bypass regulating valve 17 to close.

Claims

1. A combined high-temperature gas-gas heat exchanger, characterized in that, Comprising: A heat exchange housing (1), at both ends of the top surface of the heat exchange housing (1), an air inlet pipe (4) and an air outlet pipe (5) communicating with the interior of the heat exchange housing (1) are respectively provided, and a flue gas inlet (6) and a flue gas outlet (7) are respectively formed on the left and right side end faces of the heat exchange housing (1); A tubular heat exchange module, which is arranged in the heat exchange housing (1) on the side of the flue gas inlet (6); A plate heat exchange module, which is arranged in the heat exchange housing (1) on the side of the flue gas outlet (7); An air flow channel, the air flow channel includes the tubular heat exchange module and the plate heat exchange module, the air flow channel communicates the air inlet pipe (4) and the air outlet pipe (5), and the air flow channel is arranged in a serpentine bend.

2. The combined high-temperature gas-gas heat exchanger according to claim 1, wherein, The tubular heat exchange module includes a first tubular heat exchanger (8) and a second tubular heat exchanger (9), the plate heat exchange module includes a first plate heat exchanger (10) and a second plate heat exchanger (11), and the air flow channel further includes a first elbow (12), a second elbow (14) and a third elbow (13); In the direction from the flue gas inlet (6) to the flue gas outlet (7) are successively the first tubular heat exchanger (8), the second tubular heat exchanger (9), the first plate heat exchanger (10) and the second plate heat exchanger (11), the air outlet pipe (5) communicates with the top of the first tubular heat exchanger (8), the first elbow (12) communicates the bottom of the first tubular heat exchanger (8) and the bottom of the second tubular heat exchanger (9), the third elbow (13) communicates the top of the second tubular heat exchanger (9) and the top of the first plate heat exchanger (10), the second elbow (14) communicates the bottom of the first plate heat exchanger (10) and the bottom of the second plate heat exchanger (11), and the top of the second plate heat exchanger (11) communicates with the air inlet pipe (4).

3. The modular high-temperature gas-gas heat exchanger according to claim 2, characterized in that, The first tubular heat exchanger (8) includes a plurality of columns of arc-shaped heat pipes (81), the second tubular heat exchanger (9) includes a plurality of straight heat pipes (91), a plurality of columns of the arc-shaped heat pipes (81) and a plurality of columns of the straight heat pipes (91) are both arranged at intervals in the front-back direction of the heat exchange housing (1), the bending directions of two adjacent columns of the arc-shaped heat pipes (81) are opposite, and sealing plates are provided at the top and bottom of the arc-shaped heat pipes (81) and the straight heat pipes (91). The top of the arc-shaped heat pipe (81) passes through the sealing plate and communicates with the air outlet pipe (5), and the bottom also passes through the sealing plate and communicates with the first elbow (12). The top of the straight heat pipe (91) passes through the sealing plate and communicates with the third elbow (13), and the bottom also passes through the sealing plate and communicates with the first elbow (12).

4. The modular high-temperature gas-gas heat exchanger according to claim 3, characterized in that, An air bypass (16) communicating with the third elbow (13) is provided on the air inlet pipe (4), and a bypass regulating valve (17) is provided on the air bypass (16).

5. The modular high-temperature gas-gas heat exchanger according to claim 4, characterized in that, The first plate heat exchanger (10) and the second plate heat exchanger (11) both include a plurality of heat exchange plates (15). The plurality of heat exchange plates (15) are arranged at intervals in the front-rear direction of the heat exchange housing (1). Each heat exchange plate (15) is provided with a fluid cavity. The top of the fluid cavity in the first plate heat exchanger (10) communicates with the third elbow (13), and the bottom communicates with the second elbow (14). The top of the fluid cavity in the second plate heat exchanger (11) communicates with the air inlet pipe (4), and the bottom communicates with the second elbow (14).

6. The combined high-temperature gas-gas heat exchanger according to claim 5, characterized in that, Leak-proof ridges (151) protrude outwardly from both the top and the bottom of the heat exchange plate (15). A plurality of pits (152) and a plurality of protrusions (153) are provided on the plate surface of the heat exchange plate (15).

7. The combined high-temperature gas-gas heat exchanger according to claim 5, characterized in that, It further includes a pressure sensor (2), a temperature sensor (21) and a controller (3). The bypass regulating valve (17) is an electrically controlled valve. The bypass regulating valve (17), the pressure sensor (2) and the temperature sensor (21) are all electrically connected to the controller (3). The pressure sensor (2) is arranged in the air inlet pipe (4) and the air outlet pipe (5) to detect the gas pressure in the air flow passage. The temperature sensor (21) is arranged in the air outlet pipe (5) to detect the temperature in the air outlet pipe (5).

8. A control method, which uses the combined high-temperature gas-gas heat exchanger according to any one of claims 1-7, is characterized in that The steps are as follows: S1: Preset the pressure threshold P in the air inlet pipe (4) and the temperature threshold T in the air outlet pipe (5); S2: During use, the real-time detection value of the gas pressure in the air inlet pipe (4) by the pressure sensor (2) is P1, and the real-time detection value of the gas temperature in the air outlet pipe (5) by the temperature sensor (21) is T1; S3: When P1≥P or T1≥T, the controller (3) controls the bypass regulating valve (17) to open. When P1<P and T1<T, the controller (3) controls the bypass regulating valve (17) to close.

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