Flue gas waste heat recovery system and control method thereof

Abstract

The invention discloses a flue gas waste heat recovery system and a control method thereof, and relates to the technical field of waste heat recovery, the flue gas waste heat recovery system comprises a first filter, a heat pipe exchanger, a first fan, an OVEN furnace, a second filter, a second fan, an air supply pipeline and an exhaust main pipeline; the air supply pipeline is sequentially connected with the first filter, the condensation section of the heat pipe exchanger, the first fan and the air inlet end of the OVEN furnace; the exhaust pipeline is sequentially connected with the air outlet end of the OVEN furnace, the second filter, the evaporation section of the heat pipe heat exchanger and the second fan. By arranging the heat pipe heat exchanger, high-temperature waste heat in waste gas exhausted by the OVEN furnace is recycled and used for heating air about to enter the OVEN furnace, waste of waste heat resources and energy consumption of the OVEN furnace are reduced, and the high-temperature flue gas waste heat recovery rate is increased. The invention further discloses a control method of the flue gas waste heat recovery system. The control method is achieved based on the flue gas waste heat recovery system.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat recovery, and particularly to a flue gas waste heat recovery system and a control method thereof. Background Art

[0002] A large amount of waste heat resources are not effectively utilized, resulting in energy waste and increased carbon emissions.

[0003] In a conventional technical solution, please refer to Figure 1 , the indoor clean air (about 25°C) directly enters the OVEN furnace, and the high-temperature flue gas (230°C) discharged from the OVEN furnace exchanges heat with the clean room air (about 25°C) transported by bypass to cool down. The cooled exhaust gas (about 130°C) enters the exhaust pipe, and then the heat is directly discharged through the end of the exhaust pipe or recovered and converted for multiple uses such as heating with medium-temperature water. However, in this process, the high-temperature flue gas (230°C) discharged from the OVEN furnace directly mixes with the clean room air (about 25°C) transported by bypass to exchange heat and cool down, resulting in a large amount of high-temperature waste heat being degraded and wasted, leading to high energy consumption in the factory operation. Summary of the Invention

[0004] The main object of the present invention is to propose a flue gas waste heat recovery system and a control method thereof, aiming to improve the recovery rate of high-temperature flue gas waste heat.

[0005] To achieve the above object, the flue gas waste heat recovery system proposed by the present invention includes a first filter, a heat pipe heat exchanger, a first fan, an OVEN furnace, a second filter, a second fan, a supply air pipeline, and an exhaust main pipeline; the supply air pipeline is sequentially connected to the first filter, the condensation section of the heat pipe heat exchanger, the first fan, and the air inlet end of the OVEN furnace; the exhaust pipeline is sequentially connected to the air outlet end of the OVEN furnace, the second filter, the evaporation section of the heat pipe heat exchanger, and the second fan.

[0006] In one embodiment, the heat pipe heat exchanger includes a high-temperature heat exchange module, a high-medium temperature combined heat exchange module, and a connecting pipe; in the high-temperature heat exchange module, there are an air supply pipe and an exhaust pipe. The air supply pipe is located in the condensation section of the high-temperature heat exchange module and is connected to the air supply pipeline, and the exhaust pipe is located in the evaporation section of the high-temperature heat exchange module and is connected to the main exhaust pipeline; moreover, in the high-medium temperature combined heat exchange module, there are an air supply pipe and an exhaust pipe. The air supply pipe is located in the condensation section of the high-medium temperature combined heat exchange module and is connected to the air supply pipeline, and the exhaust pipe is located in the evaporation section of the high-medium temperature combined heat exchange module and is connected to the main exhaust pipeline; one connecting pipe connects the air supply pipe in the high-temperature heat exchange module to the air supply pipe in the high-medium temperature combined heat exchange module, and the other connecting pipe connects the exhaust pipe in the high-temperature heat exchange module to the exhaust pipe in the high-medium temperature combined heat exchange module; wherein, heat exchange tubes are provided in both the high-temperature heat exchange module and the high-medium temperature combined heat exchange module. One end of the heat exchange tube penetrates into the air supply pipe, and the other end of the heat exchange tube penetrates into the exhaust pipe. Heat dissipation fins are provided on the outer wall of the heat exchange tube located in the air supply pipe, and a steam chamber is formed inside the heat exchange tube, and a heat exchange working medium is accommodated in the steam chamber.

[0007] In one embodiment, the flue gas waste heat recovery system further includes a first differential pressure gauge and a cleaning device. The first differential pressure gauge is arranged in parallel with the evaporation section of the heat pipe heat exchanger and is used to monitor the differential pressure of the evaporation section of the heat pipe heat exchanger. The cleaning device is connected to the evaporation section of the heat pipe heat exchanger, and the first differential pressure gauge is communicatively connected to the cleaning device; and / or, the flue gas waste heat recovery system further includes a second differential pressure gauge. The second differential pressure gauge is arranged in parallel with the second filter and is used to monitor the differential pressure of the second filter.

[0008] In one embodiment, the flue gas waste heat recovery system further includes a regulation system. The regulation system includes a first terminal controller and a second terminal controller. Electric heating tubes are provided in the OVEN furnace; both the first terminal controller and the second terminal controller are connected to the electric heating tubes and are used to monitor the actual power of the electric heating tubes; the first terminal controller is connected to the first blower and is used to control the rotation speed of the first blower, and the second terminal controller is connected to the second blower and is used to control the rotation speed of the second blower.

[0009] In one embodiment, the control system further includes a first temperature sensor, a second temperature sensor, a third temperature sensor, and a fourth temperature sensor; the first temperature sensor is disposed at the input end of the condensation section of the heat pipe heat exchanger, the second temperature sensor is disposed at the output end of the condensation section of the heat pipe heat exchanger, and both the first temperature sensor and the second temperature sensor are communicatively connected to the first terminal controller; the third temperature sensor is disposed at the input end of the evaporation section of the heat pipe heat exchanger, the fourth temperature sensor is disposed at the output end of the evaporation section of the heat pipe heat exchanger, and both the third temperature sensor and the fourth temperature sensor are communicatively connected to the second terminal controller.

[0010] In one embodiment, a first valve is provided on the air supply pipeline, and the first valve is located between the first fan and the OVEN furnace; a second valve and a third valve are provided on the exhaust air pipeline, the second valve is located between the OVEN furnace and the second filter, and the third valve is located between the heat pipe heat exchanger and the second fan.

[0011] In one embodiment, the flue gas waste heat recovery system further includes an exhaust air branch pipeline, one end of the exhaust air branch pipeline is connected to the air outlet end of the OVEN furnace, the other end of the exhaust air branch pipeline is connected to the second fan, and a fourth valve is provided on the exhaust air branch pipeline.

[0012] The present invention also provides a control method for a flue gas waste heat recovery system, which is implemented based on the flue gas waste heat recovery system described in the above embodiments.

[0013] The control method of the flue gas waste heat recovery system includes the following steps:

[0014] Obtain the actual power and rated power of the electric heating tube;

[0015] Adjust the actual air volume of the flue gas waste heat recovery system according to the ratio of the actual power to the rated power;

[0016] Adjust the actual power of the electric heating tube according to the temperature value monitored by the second temperature sensor.

[0017] In one embodiment, the step of adjusting the air volume of the flue gas waste heat recovery system according to the ratio of the actual power to the rated power specifically includes the following steps:

[0018] Select the operation mode of the flue gas waste heat recovery system according to the ratio of the actual power to the rated power, where the operation modes include three types: normal mode, IDLE mode, and DOWN mode:

[0019] Select the normal mode when the actual power ≥ 70% of the rated power, select the IDLE mode when 30% of the rated power ≤ actual power < 70% of the rated power, and select the DOWN mode when the actual power < 30% of the rated power;

[0020] Adjust the actual air volume of the flue gas waste heat recovery system according to the operating mode:

[0021] When the operating mode is the normal mode, adjust the actual air volume of the flue gas waste heat recovery system to 100% of the rated air volume; when the operating mode is the IDLE mode, adjust the actual air volume of the flue gas waste heat recovery system to 50% - 70% of the rated air volume; when the operating mode is the DOWN mode, adjust the actual air volume of the flue gas waste heat recovery system to 20% - 30% of the rated air volume.

[0022] In one embodiment, the set value of the inlet temperature of the OVEN furnace is A °C to B °C, where A < B;

[0023] The step of adjusting the actual power of the electric heating tube according to the temperature value monitored by the second temperature sensor specifically includes the following steps:

[0024] Obtain the temperature value monitored by the second temperature sensor;

[0025] Judge the magnitude of the temperature value monitored by the second temperature sensor:

[0026] If the temperature value monitored by the second temperature sensor < A, then increase the actual power of the electric heating tube;

[0027] If the temperature value monitored by the second temperature sensor > B, then decrease the actual power of the electric heating tube;

[0028] If A ≤ the temperature value monitored by the second temperature sensor ≤ B, then end the adjustment.

[0029] The flue gas waste heat recovery system proposed by the present invention includes a first filter, a heat pipe heat exchanger, a first fan, an OVEN furnace, a second filter, a second fan, a supply air pipeline, and an exhaust main pipeline; the supply air pipeline is sequentially connected to the first filter, the condensation section of the heat pipe heat exchanger, the first fan, and the air inlet end of the OVEN furnace; the exhaust pipeline is sequentially connected to the air outlet end of the OVEN furnace, the second filter, the evaporation section of the heat pipe heat exchanger, and the second fan. By setting the heat pipe heat exchanger, the present invention recovers the high-temperature waste heat in the waste gas discharged from the OVEN furnace and uses it to heat the air about to enter the OVEN furnace, reducing the waste of waste heat resources and the energy consumption of the OVEN furnace, and improving the recovery rate of high-temperature flue gas waste heat. Description of the Drawings

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0031] Figure 1 It is a schematic flow chart of flue gas emission in conventional technology;

[0032] Figure 2 It is a schematic flow chart of flue gas emission in the flue gas waste heat recovery system provided by the present invention;

[0033] Figure 3 It is a schematic structural diagram of an embodiment of the flue gas waste heat recovery system provided by the present invention;

[0034] Figure 4 For Figure 3 It is a schematic structural diagram of an embodiment of the heat pipe heat exchanger in

[0035] Figure 5 For Figure 4 It is a schematic structural diagram of an embodiment of the heat exchange tube in

[0036] Figure 6 It is a flowchart of an embodiment of the control method of the flue gas waste heat recovery system provided by the present invention;

[0037] Figure 7 It is a flowchart of another embodiment of the control method of the flue gas waste heat recovery system provided by the present invention.

[0038] Explanation of the reference numerals in the drawings:

[0039] 100, flue gas waste heat recovery system;

[0040] 1, first filter;

[0041] 2, heat pipe heat exchanger; 2A, high-temperature heat exchange module; 2B, high-medium temperature combined heat exchange module; 2C, connecting pipe; 21, air supply pipe; 22, exhaust pipe; 23, heat exchange tube; 231, outer shell; 232, wick; 233, heat dissipation fins; 23a, steam chamber;

[0042] 3, first fan; 4, OVEN furnace; 5, second filter; 6, second fan;

[0043] 7, air supply pipeline; 71, first valve;

[0044] 8, main exhaust pipeline; 81, second valve; 82, third valve;

[0045] 9. First differential pressure gauge; 10. Second differential pressure gauge; 11. First temperature sensor; 12. Second temperature sensor; 13. Third temperature sensor; 14. Fourth temperature sensor;

[0046] 15. Exhaust branch pipeline; 151. Fourth valve.

[0047] The realization, functional features and advantages of the purpose of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0048] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0049] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0050] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution that satisfies both A and B at the same time. In addition, the technical solutions between the embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0051] The present invention provides a flue gas waste heat recovery system 100.

[0052] Please refer to Figures 2 to 3, in an embodiment of the present invention, the flue gas waste heat recovery system 100 includes a first filter 1, a heat pipe heat exchanger 2, a first fan 3, an OVEN furnace 4, a second filter 5, a second fan 6, a supply air pipeline 7, and an exhaust main pipeline 8; the supply air pipeline 7 is sequentially connected to the first filter 1, the condensation section of the heat pipe heat exchanger 2, the first fan 3, and the air inlet end of the OVEN furnace 4; the exhaust main pipeline 8 is sequentially connected to the air outlet end of the OVEN furnace 4, the second filter 5, the evaporation section of the heat pipe heat exchanger 2, and the second fan 6.

[0053] In this embodiment, the supply air pipeline 7 is used to supply fresh air to the OVEN furnace 4, and the high-temperature flue gas discharged from the OVEN furnace 4 is discharged through the exhaust main pipeline 8. In order to improve the waste heat recovery rate of the high-temperature flue gas, the flue gas waste heat recovery system 100 of the present invention is further provided with a heat pipe heat exchanger 2. The evaporation section of the heat pipe heat exchanger 2 is connected to the exhaust main pipeline 8, and the condensation section of the heat pipe heat exchanger 2 is connected to the supply air pipeline 7. The heat pipe heat exchanger 2 is used to recover the heat of the high-temperature flue gas in the exhaust main pipeline 8 and transfer it to the supply air pipeline 7 for heating the fresh air that is about to enter the OVEN furnace 4.

[0054] Specifically, the 25°C external fresh air sequentially passes through the first filter 1 and the supply air pipeline 7 and enters the condensation section of the heat pipe heat exchanger 2. After being preheated by the heat pipe heat exchanger 2, it will obtain a gas at about 185°C. Then, after passing through the first fan 3, it enters the OVEN furnace 4 to participate in industrial production. The high-temperature flue gas generated by the OVEN furnace 4 at about 230°C is led out through the exhaust main pipeline 8, passes through the second filter 5 to remove oil mist particles, and then enters the evaporation section of the heat pipe heat exchanger 2. After heat exchange by the heat pipe heat exchanger 2, it will obtain a hot exhaust gas at about 70°C. Then, after passing through the second fan 6, it is discharged or further recovered. The waste heat recovery of the high-temperature flue gas is realized, the waste heat recovery rate is improved, and the energy consumption of boiler operation is reduced. And this process can feedback signals such as temperature, pressure, and pressure difference in the system, and the control system controls the air volume of the system and changes the operation mode, which also ensures the reliable operation of the system. The first filter 1 is used to filter impurities such as dust in the air to prevent impurities from entering the OVEN furnace 4 and affecting industrial production. The second filter 5 is used to filter oil stain particles and the like discharged from the OVEN furnace 4 to avoid blockage of the heat pipe heat exchanger 2 by oil stains and the like, resulting in a reduction in heat exchange efficiency. Among them, the first fan 3 can preferably adopt an axial flow fan, and the second fan 6 can preferably adopt a centrifugal fan. It should be noted that in the evaporation section of the heat pipe heat exchanger 2, the refrigerant in the heat pipe heat exchanger 2 absorbs heat and evaporates into a gas state and flows to the condensation section of the heat pipe heat exchanger 2. In the condensation section, the refrigerant releases heat and condenses into a liquid state and flows back to the evaporation section for the next cycle.

[0055] The flue gas waste heat recovery system 100 proposed in this embodiment includes a first filter 1, a heat pipe heat exchanger 2, a first fan 3, an OVEN furnace 4, a second filter 5, a second fan 6, a supply air pipeline 7, and an exhaust main pipeline 8; the supply air pipeline 7 is sequentially connected to the first filter 1, the condensation section of the heat pipe heat exchanger 2, the first fan 3, and the air inlet end of the OVEN furnace 4; the exhaust main pipeline 8 is sequentially connected to the air outlet end of the OVEN furnace 4, the second filter 5, the evaporation section of the heat pipe heat exchanger 2, and the second fan 6. By setting the heat pipe heat exchanger 2, the present invention recovers the high-temperature waste heat in the exhaust gas discharged from the OVEN furnace 4 and uses it to heat the air about to enter the OVEN furnace 4, reducing the waste of waste heat resources and the energy consumption of the OVEN furnace 4, and improving the recovery rate of high-temperature flue gas waste heat.

[0056] Further, please refer to Figures 3 to 5 , in an embodiment of the present invention, it is characterized in that the heat pipe heat exchanger 2 includes a high-temperature heat exchange module 2A, a high-medium temperature combined heat exchange module 2B, and a connecting pipe 2C; a supply air pipe 21 and an exhaust air pipe 22 are provided in the high-temperature heat exchange module 2A, a supply air pipe 21 is located in the condensation section of the high-temperature heat exchange module 2A and is connected to the supply air pipeline 7, an exhaust air pipe 22 is located in the evaporation section of the high-temperature heat exchange module 2A and is connected to the exhaust main pipeline 8; moreover, another supply air pipe 21 and another exhaust air pipe 22 are provided in the high-medium temperature combined heat exchange module 2B, another supply air pipe 21 is located in the condensation section of the high-medium temperature combined heat exchange module 2B and is connected to the supply air pipeline 7, another exhaust air pipe 22 is located in the evaporation section of the high-medium temperature combined heat exchange module 2B and is connected to the exhaust main pipeline 8; a connecting pipe 2C connects the supply air pipe 21 in the high-temperature heat exchange module 2A with the supply air pipe 21 in the high-medium temperature combined heat exchange module 2B, and another connecting pipe 2C connects the exhaust air pipe 22 in the high-temperature heat exchange module 2A with the exhaust air pipe 22 in the high-medium temperature combined heat exchange module 2B; wherein, heat exchange tubes 23 are provided in both the high-temperature heat exchange module 2A and the high-medium temperature combined heat exchange module 2B. Inside each module, one end of the heat exchange tube 23 penetrates into the supply air pipe 21, the other end of the heat exchange tube 23 penetrates into the exhaust air pipe 22, heat dissipation fins 233 are provided on the outer wall of the heat exchange tube 23 located in the supply air pipe 21, and a steam cavity 23a is formed inside the heat exchange tube 23, and a heat exchange working medium is accommodated in the steam cavity 23a.

[0057] In this embodiment, a heat pipe heat exchanger 2 is adopted in this embodiment. By adjusting the system pressure, the evaporation temperature of the heat exchange working medium in the heat exchange tube 23 is controlled to achieve the recovery of the heat of the high-temperature flue gas. Among them, the liquid heat exchange working medium absorbs heat and evaporates into a gas in the evaporation section of the heat pipe heat exchanger 2 and moves to the condensation section of the heat pipe heat exchanger 2. In the condensation section of the heat pipe heat exchanger 2, the gaseous heat exchange working medium releases heat and condenses into a liquid and flows back to the evaporation section of the heat pipe heat exchanger 2. In this way, the temperature conversion between the clean fresh air and the high-temperature flue gas is efficiently achieved.

[0058] Specifically, the heat exchange principle of the heat exchange tube 23 is to utilize evaporation refrigeration to generate a temperature difference at both ends of the heat exchange tube 23, enabling rapid heat conduction. The interior of the heat exchange tube 23 is evacuated and filled with an appropriate heat exchange working fluid, such as methanol, propanol, water, ammonia, etc. Its boiling point can be controlled by adjusting the pressure within the heat exchange tube 23, thereby achieving different evaporation temperatures under different operating conditions. The heat exchange tube 23 includes a housing 231 and a wick 232. An evaporation chamber for accommodating the heat exchange working fluid is formed within the housing 231, and the inner wall of the housing 231 is provided with a wick 232, which is composed of a capillary porous material. It should be noted that one end of the heat exchange tube 23 is the evaporation end, which is located within the evaporation section of the heat pipe heat exchanger 2. The evaporation section is a section within the exhaust air duct 22. The other end of the heat exchange tube 23 is the condensation end, which is located within the condensation section of the heat pipe heat exchanger 2. The condensation section is a section within the supply air duct 21. The descriptions of the evaporation section and the condensation section of the heat pipe heat exchanger 2 in this application can refer to the above explanations. When the evaporation end of the heat exchange tube 23 is heated, the liquid in the evaporation chamber at the evaporation end rapidly evaporates. The vapor flows towards the condensation end under a small pressure difference and releases heat, recondensing into a liquid. The liquid then flows back to the evaporation end along the porous material by capillary action, and this cycle continues indefinitely. Heat is transferred from the evaporation end of the heat pipe to the condensation end. This cycle occurs rapidly, and heat can be continuously conducted away. The intermediate partition of the heat pipe heat exchanger 2 can completely separate the cold and hot fluids. Even when a single heat exchange tube 23 is damaged during operation due to reasons such as wear, corrosion, or overheating, the fluids in the condensation section and the evaporation section will not leak and mix. The head end of each heat exchange tube 23 is placed in the evaporation section, and the welded end is placed in the condensation section. Even if leakage occurs, it will not affect the OVEN furnace 4. The cold and hot fluids of the heat pipe heat exchanger 2 flow completely separately and in opposite directions, that is, the flow directions of the fresh air and the high-temperature flue gas are opposite, and it is easy to achieve countercurrent heat exchange between the cold and hot fluids, ensuring sufficient heat exchange between the fresh air and the high-temperature flue gas. Both the cold fluid and the hot fluid flow outside the tubes. Since the heat transfer coefficient of the flow outside the tubes is much higher than that of the flow inside the tubes, it is very economical for low-grade heat energy recovery. The outer wall of the heat exchange tube 23 in the condensation section is provided with heat dissipation fins 233, and the outer wall of the heat exchange tube 23 in the evaporation section is a smooth tube wall. It should be noted that the heat pipe heat exchanger 2 can solve the problems of internal wear and ash blockage of the heat pipe heat exchanger 2 by changing the structure and expanding the heating surface. Because the fresh air without oil contamination is introduced into the condensation section, heat dissipation fins 233 can be provided on the outer wall of the heat exchange tube 23 in the condensation section to improve the heat exchange efficiency. There is still a small amount of oil mist in the flue gas in the evaporation section after filtration. For easy cleaning and to extend the service life, the outer wall of the heat exchange tube 23 in the evaporation section adopts a smooth tube structure to reduce oil mist adhesion and facilitate cleaning.

[0059] More specifically, inside the heat pipe heat exchanger 2, the cold and hot fluids are separated by an intermediate partition, that is, the fresh air and the high-temperature flue gas are separated by an intermediate partition. The intermediate partition divides the heat pipe heat exchanger 2 into an independent air supply pipe 21 and an exhaust pipe 22. The heat exchange tubes 23 are passed through the intermediate partition, and the heat exchange tubes 23 and the partition are connected by full-weld welding. In order to achieve cascaded heat recovery, the heat pipe heat exchanger 2 of this embodiment adopts two-stage heat recovery, including a high-temperature heat exchange module 2A and a high-medium temperature combined heat exchange module 2B. The two modules are connected together through a connecting pipe 2C. Each module includes an air supply pipe 21, an exhaust pipe 22, and heat exchange tubes 23. The connecting pipe 2C can be connected with SUS304 stainless steel by full-weld flange. The outside of the connecting pipe 2C is wrapped with heat insulation material, and the heat insulation material can be made of glass fiber board, foam, etc. The outside of the heat insulation material can be covered with fine-grained aluminum plate for protection. The joints of the connecting pipe 2C are sealed with rivets or seals. By adjusting the system pressure, the evaporation temperature of the medium inside the heat pipe is controlled to achieve cascaded heat recovery of the high-temperature flue gas heat. The outer wall of the condensation end of the heat exchange tube 23 is provided with a fin structure, and the outer wall of the evaporation end of the heat exchange tube 23 is a smooth tube structure. Since the evaporation end of the heat exchange tube 23 is in contact with the high-temperature flue gas discharged from the OVEN furnace 4, such a setting is convenient for cleaning the small amount of oil mist after the high-temperature flue gas is filtered, and extends the service life. In addition, the heat pipe heat exchanger 2 of this embodiment includes a high-temperature heat exchange module 2A, a high-medium temperature combined heat exchange module 2B, and a connecting pipe 2C, that is, two-stage heat exchange modules are adopted. Compared with the traditional heat exchanger, when the temperature difference is large, for example, in this embodiment, from 230 °C to 70 °C, the heat exchange is insufficient, resulting in low heat recovery efficiency and energy waste. However, the two-stage heat exchange module of this embodiment can adapt to the gradient of heat change, achieve cascaded heat recovery, and improve the heat recovery efficiency.

[0060] The flue gas (about 230 °C) generated by the OVEN furnace 4 is led out and passed through a filter to remove oil mist particles, and then exchanges heat with the evaporation end of the heat exchange tube 23 in the heat exchanger 2. Specifically, it first exchanges heat through the high-temperature heat exchange module 2A and cools down to T1, then exchanges heat through the medium-high temperature combined heat exchange module and cools down to about 70 °C, and finally is discharged into the external exhaust pipe by the second fan 6. The external fresh air (about 25 °C) enters the condensation section of the heat pipe heat exchanger 2 after being treated by the first filter 1. It first exchanges heat through the medium-high temperature combined heat exchange module and warms up to T2, and then exchanges heat through the high-temperature heat exchange module 2A and warms up to about 185 °C, and enters the OVEN furnace through the first fan 3 for recycling.

[0061] Further, please refer to Figure 3, in an embodiment of the present invention, the flue gas waste heat recovery system 100 further includes a first differential pressure gauge 9 and a cleaning device. The first differential pressure gauge 9 is arranged in parallel with the evaporation section of the heat pipe heat exchanger 2 and is used to monitor the differential pressure of the evaporation section of the heat pipe heat exchanger 2. The cleaning device is connected to the evaporation section of the heat pipe heat exchanger 2, and the first differential pressure gauge 9 is communicatively connected to the cleaning device; and / or, the flue gas waste heat recovery system 100 further includes a second differential pressure gauge 10, and the second differential pressure gauge 10 is arranged in parallel with the second filter 5 and is used to monitor the differential pressure of the second filter 5.

[0062] In this embodiment, the flue gas waste heat recovery system 100 further includes a first differential pressure gauge 9 and a cleaning device. The first differential pressure gauge 9 is arranged in parallel at both ends of the evaporation section of the heat pipe heat exchanger 2, that is, the first differential pressure gauge 9 is arranged in parallel with the evaporation section of the heat pipe heat exchanger 2 and is used to monitor the differential pressure of the evaporation section of the heat pipe heat exchanger 2. The evaporation section of the heat pipe heat exchanger 2 is provided with a cleaning water inlet and a cleaning water outlet communicating with the exhaust duct 22. The cleaning device is connected to the evaporation section of the heat pipe heat exchanger 2 and communicates with the cleaning water inlet. The first differential pressure gauge 9 is communicatively connected to the cleaning device, and the cleaning device can obtain the differential pressure information monitored by the first differential pressure gauge 9 to judge whether it is necessary to clean the evaporation section of the heat pipe heat exchanger 2. That is, by monitoring the differential pressure of the evaporation section of the heat pipe heat exchanger 2 in real time and being able to be linked with the cleaning device, the occurrence of serious blockage of the heat pipe heat exchanger 2 can be prevented. For fluids with a high dust content, the heat pipe heat exchanger 2 can solve the problems of wear and ash blockage of the heat pipe heat exchanger 2 by changing the structure and expanding the heating surface. The purpose of arranging the second differential pressure gauge 10 in parallel with the second filter 5 is to facilitate the online replacement of the filter element of the second filter 5. The second differential pressure gauge 10 monitors the differential pressure at both ends of the second filter 5 in real time. When the differential pressure exceeds the designed differential pressure range, it indicates that the filter element is blocked, and the staff can be prompted to replace the filter element. It should be noted that the communication connection in this application can be directly electrically connected through a wire or can be realized through a wireless connection, which can be referred to the prior art and will not be elaborated in the subsequent embodiments for the same reason.

[0063] Further, please refer to Figure 3 , in an embodiment of the present invention, the flue gas waste heat recovery system 100 further includes a regulation system. The regulation system includes a first terminal controller and a second terminal controller. Electric heating tubes are provided in the OVEN furnace 4; both the first terminal controller and the second terminal controller are connected to the electric heating tubes and are used to monitor the actual power of the electric heating tubes; the first terminal controller is connected to the first fan 3 and is used to control the rotation speed of the first fan 3, and the second terminal controller is connected to the second fan 6 and is used to control the rotation speed of the second fan 6.

[0064] In this embodiment, to ensure that the system operation fully meets the process requirements and save the system energy consumption, the air volumes of the first fan 3 and the second fan 6 can be adjusted adaptively. The first terminal controller can adjust the rotation speed of the first fan 3 according to the power of the electric heating tube, and then adjust the air intake volume. Similarly, the second terminal controller can adjust the rotation speed of the second fan 6 according to the power of the electric heating tube, and then adjust the air output volume. In this way, different air volumes can be output according to the power of the OVEN furnace 4 under different working conditions. For example, when the power of the OVEN furnace 4 increases, the output air volume increases; when the power of the OVEN furnace 4 decreases, the output air volume decreases, so that the fans are always matched with the power of the OVEN furnace 4, avoiding waste of fan energy consumption and ensuring the normal progress of industrial production.

[0065] Further, please refer to Figure 3 , in an embodiment of the present invention, the control system further includes a first temperature sensor 11, a second temperature sensor 12, a third temperature sensor 13, and a fourth temperature sensor 14; the first temperature sensor 11 is arranged at the input end of the condensation section of the heat pipe heat exchanger 2, the second temperature sensor 12 is arranged at the output end of the condensation section of the heat pipe heat exchanger 2, and both the first temperature sensor 11 and the second temperature sensor 12 are communicatively connected to the first terminal controller; the third temperature sensor 13 is arranged at the input end of the evaporation section of the heat pipe heat exchanger 2, the fourth temperature sensor 14 is arranged at the output end of the evaporation section of the heat pipe heat exchanger 2, and both the third temperature sensor 13 and the fourth temperature sensor 14 are communicatively connected to the second terminal controller.

[0066] In this embodiment, the first temperature sensor 11 and the second temperature sensor 12 are used to monitor the temperature of the condensation section of the heat pipe heat exchanger 2 and calculate the temperature difference, so as to calculate the heat transfer efficiency of the condensation section of the heat pipe heat exchanger 2. When the heat transfer rate of the condensation section of the heat pipe heat exchanger 2 decreases due to reasons such as dust accumulation, the first terminal controller can discover this situation through the temperature values fed back by the first temperature sensor 11 and the second temperature sensor 12, and then increase the air volume of the first fan 3 to ensure the supply of the heat transfer amount. Similarly, the third temperature sensor 13 and the fourth temperature sensor 14 are used to monitor the temperature of the evaporation section of the heat pipe heat exchanger 2 and calculate the temperature difference, so as to calculate the heat transfer efficiency of the evaporation section of the heat pipe heat exchanger 2. When the heat transfer rate of the evaporation section of the heat pipe heat exchanger 2 decreases due to reasons such as dust accumulation and oil stain, the second terminal controller can discover this situation through the temperature values fed back by the third temperature sensor 13 and the fourth temperature sensor 14, and then increase the air volume of the second fan 6 to ensure the supply of the heat transfer amount. It should be noted that when the temperature difference exceeds the design range, adjusting the first fan 3 and the second fan 6 may not effectively solve the problem of the decrease in the heat transfer rate caused by dust accumulation and oil stain adhesion in the heat pipe heat exchanger 2. At this time, this situation can be quickly discovered through each temperature sensor and the heat pipe heat exchanger 2 can be cleaned.

[0067] Further, please refer to Figure 3 , in an embodiment of the present invention, a first valve 71 is provided on the air supply pipeline 7, and the first valve 71 is located between the first blower 3 and the OVEN furnace 4; a second valve 81 and a third valve 82 are provided on the main exhaust pipeline 8, the second valve 81 is located between the OVEN furnace 4 and the second filter 5, and the third valve 82 is located between the heat pipe heat exchanger 2 and the second blower 6.

[0068] In this embodiment, considering that the heat pipe heat exchanger 2 may need maintenance or cleaning after long-term use, in the maintenance and cleaning conditions, in order to prevent the escape of dust and other pollutants to locations such as the OVEN furnace 4 and affect the normal operation or cause pollution, a first valve 71 is provided on the air supply pipeline 7 between the first blower 3 and the OVEN furnace 4, a second valve 81 is provided on the main exhaust pipeline 8 between the OVEN furnace 4 and the second filter 5, and a third valve 82 is provided between the heat pipe heat exchanger 2 and the second blower 6. And by setting the above valves, the opening degree of the air supply or exhaust pipe 22 can be adjusted, facilitating the regulation of the flow rate in the pipeline.

[0069] Further, please refer to Figure 3 , in an embodiment of the present invention, the flue gas waste heat recovery system 100 further includes an exhaust branch pipeline 15. One end of the exhaust branch pipeline 15 is connected to the air outlet end of the OVEN furnace 4, the other end of the exhaust branch pipeline 15 is connected to the second blower 6, and a fourth valve 151 is provided on the exhaust branch pipeline 15.

[0070] In this embodiment, considering that the heat pipe heat exchanger 2 may need maintenance or cleaning after long-term use, in the maintenance and cleaning conditions, in order to avoid losses caused by the shutdown of the entire system, an exhaust branch pipeline 15 is provided on the main exhaust pipeline 8. One end of the exhaust branch pipeline 15 is connected to the air outlet end of the OVEN furnace 4, and the other end of the exhaust branch pipeline 15 is connected to the second blower 6. When the heat pipe heat exchanger 2 is being repaired, the main exhaust pipeline 8 can be closed and the exhaust branch pipeline 15 can be enabled, and the high-temperature flue gas can then be temporarily discharged from the exhaust branch pipeline 15 to ensure the normal progress of industrial production. A fresh air inlet is provided at the end of the exhaust branch pipeline 15 far from the OVEN furnace 4, and the high-temperature flue gas and the low-temperature fresh air are mixed in the exhaust branch pipeline 15 and then enter the main exhaust pipeline 8 for discharge.

[0071] The present invention also proposes a control method for the flue gas waste heat recovery system 100, which is implemented based on the flue gas waste heat recovery system 100 in the above-mentioned embodiments.

[0072] Please refer to Figure 6 , in an embodiment of the present invention, the control method of the flue gas waste heat recovery system 100 includes the following steps:

[0073] Obtain the actual power and rated power of the electric heating tube;

[0074] Adjust the actual air volume of the flue gas waste heat recovery system 100 according to the ratio of the actual power to the rated power;

[0075] Adjust the actual power of the electric heating tube according to the temperature value monitored by the second temperature sensor 12.

[0076] In this embodiment, in order to make the air volume in the flue gas waste heat recovery system 100 just meet the industrial production, that is, in order to make the air volume in the flue gas waste heat recovery system 100 match the power of the electric heating tube, this embodiment obtains the actual power and rated power of the electric heating tube through the first terminal controller and uses them to adjust the rotation speed of the first fan 3 and then adjust the air volume of the first fan 3. The rated power can be input presetly. When the fan is not replaced, it can be input once at the beginning. The actual power needs to be obtained by the first terminal controller. Similarly, obtain the actual power and rated power of the electric heating tube through the second terminal controller and use them to adjust the rotation speed of the second fan 6 and then adjust the air volume of the second fan 6. The rated power can be input presetly. When the fan is not replaced, it can be input once at the beginning. The actual power needs to be obtained by the second terminal controller. It should be noted that the air volume of the entire system is the sum of the air volume of the first fan 3 and the air volume of the second fan 6. Generally, the air volumes of the first fan 3 and the second fan 6 can be kept equal. When dust accumulates in the heat pipe heat exchanger 2 and other situations occur, the air volume of the first fan 3 or the second fan 6 can be slightly adjusted appropriately. After the air volume is adjusted, the heat exchange amount of the heat pipe heat exchanger 2 changes. The temperature at the output end of the condensation section of the heat pipe heat exchanger 2 is monitored by the second temperature sensor 12, that is, the temperature of the new air about to enter the OVEN furnace 4 is detected by the second temperature sensor 12, and then the power of the electric heating tube in the OVEN furnace 4 is adjusted. For example, when the temperature of the new air about to enter the OVEN furnace 4 is relatively high, the power of the electric heating tube can be appropriately reduced to reduce energy consumption. When the temperature of the new air about to enter the OVEN furnace 4 is relatively low, in order to meet the industrial production requirements, the power of the electric heating tube can be appropriately increased to meet the heat supply. In this way, a cycle is completed. If the power of the electric heating tube after this cycle is not within the designed power range, the next cycle can be carried out until the power of the electric heating tube is maintained within the designed power range to meet the requirements of energy conservation and system safety.

[0077] Specifically, please refer to Figure 7 , in an embodiment of the present invention, the steps of adjusting the air volume of the flue gas waste heat recovery system 100 according to the ratio of the actual power to the rated power specifically include the following steps:

[0078] Select the operation mode of the flue gas waste heat recovery system 100 according to the ratio of the actual power to the rated power, where the operation mode includes three types: normal mode, IDLE mode, and DOWN mode:

[0079] Select the normal mode when the actual power ≥ 70% of the rated power, select the IDLE mode when 30% of the rated power ≤ actual power < 70% of the rated power, and select the DOWN mode when the actual power < 30% of the rated power;

[0080] Adjust the actual air volume of the flue gas waste heat recovery system 100 according to the operating mode:

[0081] When the operating mode is the normal mode, adjust the actual air volume of the flue gas waste heat recovery system 100 to 100% of the rated air volume; when the operating mode is the IDLE mode, adjust the actual air volume of the flue gas waste heat recovery system 100 to 50% - 70% of the rated air volume; when the operating mode is the DOWN mode, adjust the actual air volume of the flue gas waste heat recovery system 100 to 20% - 30% of the rated air volume.

[0082] In this embodiment, in order to make the energy consumption of the flue gas waste heat recovery system 100 match various working conditions in actual industrial production and ensure that the flue gas waste heat recovery system 100 can operate safely, stably and reliably for a long time. The flue gas waste heat recovery system 100 of this embodiment is designed with three operating modes: normal mode, IDLE mode and DOWN mode. The normal mode corresponds to the most common production conditions in industrial production. At this time, the industrial heat demand is large, so the power of the electric heating tube is large. Correspondingly, the air volume demand in the system is large. The IDLE mode corresponds to the conditions when the equipment is on standby, before short-term shutdown preparation, and when the production demand is low. At this time, the industrial heat demand is relatively lower than that in the normal mode. Therefore, the power of the electric heating tube is maintained in a lower range to ensure the basic process requirements. Correspondingly, the air volume in the system is maintained in a lower range. The DOWN mode corresponds to the conditions when the equipment is shut down for a long time, maintained and repaired, and during non-production periods at night. At this time, the industrial heat demand is the lowest or there is no demand, and only the system anti-freezing or the lowest circulation needs to be maintained. Therefore, the power of the electric heating tube and the air volume in the system are maintained at the lowest range.

[0083] It should be noted that the actual power of the electric heating tube can be calculated by monitoring the current signal of the electric heating tube. The current signal can be automatically collected by the first terminal controller or the second terminal controller in the power distribution cabinet of the OVEN furnace 4. The first terminal controller calculates the power of the electric heating tube according to the current signal and correspondingly adjusts the wind speed of the first fan 3 and then adjusts the air volume of the first fan 3. The second terminal controller calculates the power of the electric heating tube according to the current signal and correspondingly adjusts the wind speed of the second fan 6 and then adjusts the air volume of the second fan 6. The total air volume in the whole system is adjusted by adjusting the air volume of the first fan 3 and the second fan 6 to match the power of the electric heating tube.

[0084] Specifically, please refer to Figure 7, in an embodiment of the present invention, the set value of the intake air temperature of the OVEN furnace 4 is A °C to B °C, where A < B; the steps of adjusting the actual power of the electric heating tube according to the temperature value monitored by the second temperature sensor 12 specifically include the following steps:

[0085] Obtain the temperature value monitored by the second temperature sensor 12;

[0086] Judge the magnitude of the temperature value monitored by the second temperature sensor 12:

[0087] If the temperature value monitored by the second temperature sensor 12 < A, then increase the actual power of the electric heating tube;

[0088] If the temperature value monitored by the second temperature sensor 12 > B, then decrease the actual power of the electric heating tube;

[0089] If A ≤ the temperature value monitored by the second temperature sensor 12 ≤ B, then end the adjustment.

[0090] In this embodiment, the set value of the intake air temperature of the OVEN furnace 4 is 180 °C to 190 °C. After the air volume adjustment in the previous step, the heat exchange amount of the heat pipe heat exchanger 2 changes. The temperature at the output end of the condensation section of the heat pipe heat exchanger 2 is monitored by the second temperature sensor 12, that is, the temperature of the new air about to enter the OVEN furnace 4 is detected by the second temperature sensor 12, and then the power of the electric heating tube in the OVEN furnace 4 is adjusted. For example, when the temperature of the new air about to enter the OVEN furnace 4 is relatively high (>190 °C), the power of the electric heating tube can be appropriately reduced to reduce energy consumption. When the temperature of the new air about to enter the OVEN furnace 4 is relatively low (<180 °C), in order to meet the requirements of industrial production, the power of the electric heating tube can be appropriately increased to meet the heat supply. In this way, one cycle is completed. If the power of the electric heating tube after this cycle is not within the designed power range, the next cycle can be carried out until the power of the electric heating tube is maintained within the designed power range to meet the requirements of energy conservation and system safety.

[0091] The above is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A flue gas waste heat recovery system, characterized in that: The flue gas waste heat recovery system comprises a first filter (1), a heat pipe heat exchanger (2), a first fan (3), an OVEN furnace (4), a second filter (5), a second fan (6), an air supply pipeline (7) and an exhaust main pipeline (8); The air supply pipeline (7) is sequentially connected to the first filter (1), the condensing section of the heat pipe heat exchanger (2), the first fan (3) and the air inlet end of the OVEN furnace (4); The main exhaust air line (8) is sequentially connected to the air outlet end of the OVEN furnace (4), the second filter (5), the evaporation section of the heat pipe heat exchanger (2), and the second fan (6).

2. The flue gas waste heat recovery system according to claim 1, characterized in that: The heat pipe heat exchanger (2) comprises a high-temperature heat exchange module (2A), a high- and medium-temperature combined heat exchange module (2B) and a communication pipe (2C); The high-temperature heat exchange module (2A) is provided with an air supply pipe (21) and an air exhaust pipe (22); the air supply pipe (21) is located in the condensation section of the high-temperature heat exchange module (2A) and is connected to the air supply pipeline (7); the air exhaust pipe (22) is located in the evaporation section of the high-temperature heat exchange module (2A) and is connected to the main exhaust pipeline (8); Furthermore, the high-medium temperature combined heat exchange module (2B) is provided with another air supply pipe (21) and another air exhaust pipe (22); the air supply pipe (21) is located in the condensing section of the high-medium temperature combined heat exchange module (2B) and is connected to the air supply pipe (7); and the air exhaust pipe (22) is located in the evaporating section of the high-medium temperature combined heat exchange module (2B) and is connected to the main exhaust pipe (8); One of the connecting pipes (2C) connects the air supply pipe (21) in the high-temperature heat exchange module (2A) with the air supply pipe (21) in the high-medium temperature combined heat exchange module (2B), and the other of the connecting pipes (2C) connects the air exhaust pipe (22) in the high-temperature heat exchange module (2A) with the air exhaust pipe (22) in the high-medium temperature combined heat exchange module (2B); The high-temperature heat exchange module (2A) and the high-medium temperature combined heat exchange module (2B) are both provided with a heat exchange tube (23), one end of the heat exchange tube (23) penetrates into the air supply tube (21), and the other end of the heat exchange tube (23) penetrates into the exhaust tube (22), and a heat dissipation fin (233) is provided on the outer wall of the heat exchange tube (23) located in the air supply tube (21), and a steam chamber (23a) is formed in the heat exchange tube (23), and a heat exchange medium is contained in the steam chamber (23a).

3. The flue gas waste heat recovery system according to claim 1, characterized in that: The flue gas waste heat recovery system further comprises a first differential pressure gauge (9) and a cleaning device, wherein the first differential pressure gauge (9) is arranged in parallel with the evaporation section of the heat pipe heat exchanger (2) and is used to monitor the pressure difference of the evaporation section of the heat pipe heat exchanger (2), and the cleaning device is connected to the evaporation section of the heat pipe heat exchanger (2), and the first differential pressure gauge (9) is in communication connection with the cleaning device; And / or, the flue gas waste heat recovery system further comprises a second differential pressure gauge, which is arranged in parallel with the second filter (5) and is used to monitor the pressure difference of the second filter (5).

4. The flue gas waste heat recovery system according to any one of claims 1 to 3, characterized in that: The flue gas waste heat recovery system further comprises a control system, the control system comprises a first terminal controller and a second terminal controller, and an electric heating tube is provided in the OVEN furnace (4); The first terminal controller and the second terminal controller are both connected to the electric heating tube and are used to monitor the actual power of the electric heating tube; The first terminal controller is connected to the first fan (3) and is used to control the rotation speed of the first fan (3), and the second terminal controller is connected to the second fan (6) and is used to control the rotation speed of the second fan (6).

5. The flue gas waste heat recovery system according to claim 4, characterized in that: The control system further comprises a first temperature sensor (11), a second temperature sensor (12), a third temperature sensor (13) and a fourth temperature sensor (14); The first temperature sensor (11) is arranged at the input end of the condensing section of the heat pipe heat exchanger (2), and the second temperature sensor (12) is arranged at the output end of the condensing section of the heat pipe heat exchanger (2), and the first temperature sensor (11) and the second temperature sensor (12) are both communicatively connected to the first terminal controller; The third temperature sensor (13) is arranged at the input end of the evaporation section of the heat pipe heat exchanger (2), and the fourth temperature sensor (14) is arranged at the output end of the evaporation section of the heat pipe heat exchanger (2). Both the third temperature sensor (13) and the fourth temperature sensor (14) are communicatively connected to the second terminal controller.

6. The flue gas waste heat recovery system according to any one of claims 1 to 3, characterized in that: The air supply pipeline (7) is provided with a first valve (71), and the first valve (71) is located between the first fan (3) and the OVEN furnace (4); The main exhaust air line (8) is provided with a second valve (81) and a third valve (82), wherein the second valve (81) is located between the OVEN furnace (4) and the second filter (5), and the third valve (82) is located between the heat pipe exchanger (2) and the second fan (6).

7. The flue gas waste heat recovery system according to any one of claims 1 to 3, characterized in that: The flue gas waste heat recovery system also includes an exhaust branch pipeline (15), one end of the exhaust branch pipeline (15) is connected to the air outlet end of the OVEN furnace (4), and the other end of the exhaust branch pipeline (15) is connected to the second fan (6), and a fourth valve (151) is provided on the exhaust branch pipeline (15).

8. A control method for a flue gas waste heat recovery system, implemented based on the flue gas waste heat recovery system as claimed in claim 5, characterized in that: The control method of the flue gas waste heat recovery system comprises the following steps: Obtaining the actual power and rated power of the electric heating tube; Adjusting the actual air volume of the flue gas waste heat recovery system according to the ratio of actual power to rated power; The actual power of the electric heating tube is adjusted according to the temperature value monitored by the second temperature sensor (12).

9. The control method of the flue gas waste heat recovery system according to claim 8, characterized in that: The step of adjusting the air volume of the flue gas waste heat recovery system according to the ratio of actual power to rated power specifically includes the following steps: The operation mode of the flue gas waste heat recovery system is selected according to the ratio of actual power to rated power. The operation modes include normal mode, IDLE mode and DOWN mode: Select the normal mode when the actual power ≥ 70% of the rated power, select the IDLE mode when 30% of the rated power ≤ actual power < 70% of the rated power, and select the DOWN mode when the actual power < 30% of the rated power; Adjust the actual air volume of the flue gas waste heat recovery system according to the operating mode: When the operating mode is the normal mode, adjust the actual air volume of the flue gas waste heat recovery system to 100% of the rated air volume; when the operating mode is the IDLE mode, adjust the actual air volume of the flue gas waste heat recovery system to 50% - 70% of the rated air volume; when the operating mode is the DOWN mode, adjust the actual air volume of the flue gas waste heat recovery system to 20% - 30% of the rated air volume.

10. The control method of the flue gas waste heat recovery system according to any one of claims 8 to 9, characterized in that: The set value of the inlet temperature of the OVEN furnace (4) is A°C to B°C, where A < B; The steps of adjusting the actual power of the electric heating tube according to the temperature value monitored by the second temperature sensor (12) specifically include the following steps: Obtain the temperature value monitored by the second temperature sensor (12); Judge the magnitude of the temperature value monitored by the second temperature sensor (12): If the temperature value monitored by the second temperature sensor (12) < A, then increase the actual power of the electric heating tube; If the temperature value monitored by the second temperature sensor (12) > B, then decrease the actual power of the electric heating tube; If A ≤ the temperature value monitored by the second temperature sensor (12) ≤ B, then end the adjustment.

Images