A boiler air and flue gas interconnection system using a combined air preheater

Abstract

The utility model relates to air preheater technical field discloses a kind of boiler air and smoke interrelated system using combined air preheater, including rotary air preheater, the top of rotary air preheater is fixedly connected with flue gas inlet pipe, the bottom of rotary air preheater is fixedly connected with flue gas discharge pipe, the bottom of flue gas discharge pipe is fixedly connected with plate flue gas cooler, the bottom of plate flue gas cooler is fixedly connected with drain pipe.The utility model is through set up single piece positioning plate or corrugated plate and adopts straight passage big corrugation, oblique corrugation and flat plate combined form, oblique corrugation between straight passage big corrugation and flat plate is sixty degrees angle with main axis, and parallel arrangement, the straight passage big corrugation of plate type one is corresponding with the flat plate of plate type two, forms ash channel, reduces the possibility of ash blocking, and plate type one and plate type two oblique corrugation cross arrangement, increase airflow disturbance, improve heat exchange capacity.

Description

Technical Field

[0001] This utility model relates to the field of air preheater technology, and in particular to a boiler flue gas interconnection system using a combined air preheater. Background Technology

[0002] Rotary air preheaters are key equipment in coal-fired power plant boiler systems that utilize waste heat from flue gas. As shown in the figure below, the heat storage elements are arranged in the rotor and rotate together with the central shaft. The heat is converted through the continuous rotation of the heat storage elements, transferring the heat in the flue gas to the cold air.

[0003] Because conventional rotary heat exchangers use corrugated plate structures for their heat transfer elements, the cold and hot end heat transfer elements typically need to be arranged at a high height, usually exceeding 2.5 meters, to ensure that the flue gas temperature is reduced to a certain level. In addition, the unit injects excessive ammonia to ensure denitrification efficiency. Furthermore, the wall temperature of the cold end heat transfer elements in the rotary heat exchanger is low, below the dew point of ammonium bisulfate. This causes liquid ammonium bisulfate to adhere to the surface of the heat transfer elements and continuously capture fly ash, resulting in ash blockage of the heat transfer elements. This leads to increased flue gas resistance, decreased heat exchange efficiency, and frequent shutdowns for cleaning.

[0004] In addition, the exhaust temperature of traditional rotary air preheaters is generally around 100 degrees Celsius. A large amount of waste heat from the flue gas is directly emitted, resulting in energy waste. Furthermore, the high flue gas temperature leads to an increase in the selection of electrostatic precipitators for downstream equipment of the air preheater, thereby increasing the investment cost of the power plant. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a boiler flue gas interconnection system using a combined air preheater.

[0006] This utility model is achieved by the following technical solution: a boiler flue gas interconnection system using a combined air preheater, including a rotary air preheater, a flue gas inlet pipe fixedly connected to the top of the rotary air preheater, a flue gas outlet pipe fixedly connected to the bottom of the rotary air preheater, a plate flue gas cooler fixedly connected to the bottom of the flue gas outlet pipe, and a drain pipe fixedly connected to the bottom of the plate flue gas cooler.

[0007] A delivery pump is fixedly connected to the right end of the plate flue gas cooler. A deaerator is fixedly connected to the bottom of the delivery pump. A water pump outlet pipe is fixedly connected to the right end of the deaerator. A front flue gas duct is fixedly connected to the bottom of the plate flue gas cooler. A primary air duct is fixedly connected to the left end of the rotary air preheater. A primary warm air duct is fixedly connected to the bottom of the primary air duct. A first plate heater is fixedly connected to the bottom of the primary air duct. A second primary warm air duct is fixedly connected to the top of the primary air duct. A secondary air duct is fixedly connected to the left end of the rotary air preheater. The rotary air preheater has a secondary hot air duct 1 fixedly connected to the top of the secondary air duct, a secondary hot air duct 2 fixedly connected to the bottom of the rotary air preheater, a second plate heater fixedly connected to the bottom of the second plate heater, a secondary air outlet fixedly connected to the bottom of the second plate heater, an SDN plate type 1 installed inside the rotary air preheater, an SDN plate type 1 fixedly connected to the bottom of the secondary air outlet, an element box installed inside the rotary air preheater, a limiting support rod snapped onto the surface of the element box, a heat storage element plate snapped onto the inside of the limiting support rod, and an installation slot opened inside the limiting support rod.

[0008] By combining the above technical solution with a rotary air preheater and a plate flue gas heat exchanger, the temperature of the flue gas at the boiler tail end is reduced from 370 degrees Celsius to approximately 80-120 degrees Celsius, maximizing the recovery of waste heat. The recovered waste heat from the flue gas heats the condensate, which is then recycled as a heat transfer medium. The plate air heat exchanger heats the primary and secondary air at the inlet of the air preheater, raising the primary cold air from -30 degrees Celsius to -180 degrees Celsius and the secondary cold air from -20 degrees Celsius to -160 degrees Celsius. The heated cold air then passes through the rotary air preheater, raising the temperature of the primary air to -340 degrees Celsius and the secondary air to -320 degrees Celsius, thus achieving the recovery of waste heat from the flue gas.

[0009] As a further improvement to the above solution, a first plate heater is fixedly connected to the left end of the plate flue gas cooler, and a second plate heater is fixedly connected to the left end of the first plate heater.

[0010] With the above technical solution, the flue gas discharged from the boiler denitrification equipment has a temperature of approximately 370 degrees Celsius. It then passes through a rotary air preheater. Remote temperature and pressure measuring points are installed at the inlet and outlet flue ducts of the rotary air preheater to monitor the flue gas temperature and flue gas-side resistance. After passing through the rotary air preheater, the flue gas temperature is approximately 220 degrees Celsius, ensuring that the wall temperature of the heat transfer elements is higher than the acid dew point of the flue gas, thus preventing ash accumulation on the heat transfer elements. The flue gas discharged from the rotary air preheater then passes through a plate flue gas cooler. The plate flue gas cooler is modularly arranged, with each module operating independently. Individual modules can be dry-burned by water-side isolation, and modules can also be repaired and replaced. The flue gas temperature can be adjusted by regulating the water flow in the plate flue gas cooler, ensuring that the outlet flue gas temperature of the plate heat exchanger remains at approximately 80 degrees Celsius under different operating conditions.

[0011] As a further improvement to the above scheme, a deaerator is fixedly connected to the bottom of the second plate heater, a deaerator is fixedly connected to the bottom of the first plate heater, and a deaerator is fixedly connected to the bottom of the plate flue gas cooler.

[0012] Through the above technical solution, cold air is discharged from the primary and secondary fans. After passing through the fans, the air temperature is about 20 to 30 degrees Celsius. Then it passes through the plate air heaters, which are modularly arranged and can be isolated. After passing through the plate air heaters, the air temperature is raised to about 160 to 180 degrees Celsius. Then it enters the rotary air preheater. The higher inlet air temperature ensures that the average wall temperature of the cold end elements of the rotary air preheater is higher than the acid dew point of the flue gas, avoiding ash accumulation on the heat transfer elements. After passing through the rotary air preheater, the air temperature of the primary and secondary air is raised to about 320 to 340 degrees Celsius. Then the primary air is conditioned and enters the coal mill, and the secondary air enters the furnace.

[0013] As a further improvement to the above solution, a delivery pump is fixedly connected to the top of the water pump outlet pipe, and the delivery pump is located at the bottom of the rotary air preheater.

[0014] Through the above technical solution, the entire boiler flue gas coupling system based on the combined air preheater is a closed-loop system. The circulating water is taken from the mixed water at the No. 8 low-temperature inlet and the No. 7 low-temperature outlet. A regulating valve is installed at the No. 8 low-temperature inlet to adjust the water flow rate according to the mixed water temperature, ensuring that the mixed water temperature reaches 70 degrees Celsius. The mixed condensate is pressurized by the circulating water pump and then flows through the plate flue gas cooler. The high-temperature flue gas heats the condensate to ~220 degrees Celsius. After flowing through the plate flue gas cooler, it is divided into three branches, which flow separately... The system bypasses the primary air plate heater, secondary air plate heater, and plate air heater. A regulating valve is installed at the outlet of the plate air heater to adjust the flow rate to the primary air plate heater and secondary air plate heater according to the different temperature requirements of the primary and secondary air, thereby adjusting the air temperature. After passing through the plate air heater, the water temperature drops to ~90 degrees Celsius. The water flowing out of the plate air heater and the bypass of the air heater is mixed and returns to the water pump inlet to form a closed loop, or it is directly returned to the condensate system.

[0015] As a further improvement to the above scheme, the first plate heater is located at the bottom of the primary air of the rotary air preheater, and the second plate heater is located at the bottom of the secondary air of the rotary air preheater.

[0016] As a further improvement to the above scheme, the drain pipe is located at the left end of the delivery pump and at the top of the deaerator.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0018] This utility model uses a combination of straight-channel large corrugations, oblique corrugations, and flat plates by setting a single positioning plate or corrugated plate. The oblique corrugations between the straight-channel large corrugations and the flat plate are at a 60-degree angle to the main axis and are arranged in parallel. The straight-channel large corrugations of plate type one correspond to the flat plate of plate type two to form a ash passage groove, reducing the possibility of ash blockage. The oblique corrugations of plate type one and plate type two are arranged in a cross pattern to increase airflow disturbance and improve heat exchange capacity.

[0019] This utility model uses single-sided or double-sided finned plates with a thickness of 1-6 mm to set up heat storage element plates. These plates are arranged in an element box at a fixed pitch. The fins are machined and can be arranged reasonably according to the heat exchange area requirements. Each fin plate has grooves at its upper and lower edges, which interlock with the element box to neatly arrange the heat storage elements. At the same time, it ensures that the gap between the heat storage element plates remains constant. Each heat storage element is fixed individually, and there is no contact between the plates, eliminating dead zones. The distance between the plates can be adjusted according to the needs of different projects. While ensuring the heat exchange effect, it also ensures the permeability of the heat storage elements, which is conducive to soot blowing. Heat transfer element plate type one and plate type two can be used alone, or they can be combined as hot end plate type and cold end plate type, respectively.

[0020] This invention utilizes a plate heat exchanger, a highly efficient heat exchange device constructed from stacked corrugated metal plates. Heat transfer between fluids is achieved through enclosed channels between the plates. The plate heat exchanger described in this patent allows for selection of plates made from different materials depending on the operating temperature, making it widely applicable and highly corrosion-resistant. It employs fully automated, oxidation-free laser welding, with weld points arranged in equilateral triangles. After welding, the plates are formed under high liquid pressure, creating olive-shaped channels. Simultaneously, the equilateral triangular weld points enhance fluid turbulence as it passes through the plates, resulting in better heat exchange efficiency than traditional tubular heat exchangers.

[0021] This invention features a fully continuous flue gas channel with airflow direction essentially parallel to the heat exchange surface. Ash particles in the flue gas flow parallel to the plate surface, minimizing wear. The water-side channel is an olive-shaped channel with equilateral triangular flow, resulting in stronger heat exchange disturbance and higher heat exchange efficiency. The plate heat exchanger adopts a modular design, with electric shut-off valves on the inlet and outlet water sides of each module, allowing for independent dry-burning. Modular online dry-burning technology is used to directionally remove ash accumulation in the plate heat exchanger, maintaining high-efficiency heat exchange. Furthermore, by adjusting the number of operating modules, the exhaust gas temperature can be flexibly controlled to adapt to different operating loads. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0023] Figure 2 This is a schematic diagram of the plate type structure of this utility model;

[0024] Figure 3 This is a schematic diagram of the component box structure of this utility model;

[0025] Figure 4 This is a schematic diagram of the disassembled component box structure of this utility model;

[0026] Figure 5 This is an enlarged schematic diagram of the structure at point A of this utility model;

[0027] Figure 6 This is a schematic diagram of the disassembled structure of the heat storage element plate of this utility model;

[0028] Figure 7 This is an enlarged schematic diagram of the structure at point B of this utility model;

[0029] Figure 8 This is a schematic diagram of the heat storage element plate structure of this utility model;

[0030] Figure 9 This is an enlarged schematic diagram of the structure at point C of this utility model.

[0031] Explanation of key symbols:

[0032] 1. Rotary air preheater; 2. Flue gas inlet pipe; 3. Flue gas outlet pipe; 4. Plate flue gas cooler; 5. Drain pipe; 6. Transfer pump; 7. Deaerator; 8. Water pump outlet pipe; 9. Front flue gas duct; 10. Primary air of rotary air preheater; 11. Primary warm air duct one; 12. First plate heater; 13. Primary warm air duct two; 14. Secondary air of rotary air preheater; 15. Secondary warm air duct one; 16. Secondary warm air duct two; 17. Second plate heater; 18. Secondary air outlet; 19. Plate type one; 20. Plate type two; 21. Component box; 22. Limiting support rod; 23. Heat storage element plate; 24. Mounting slot. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0034] Example:

[0035] Please combine Figure 1-9 This embodiment of a boiler flue gas interconnection system using a combined air preheater includes a rotary air preheater 1, a flue gas inlet pipe 2 fixedly connected to the top of the rotary air preheater 1, a flue gas outlet pipe 3 fixedly connected to the bottom of the rotary air preheater 1, a plate flue gas cooler 4 fixedly connected to the bottom of the flue gas outlet pipe 3, and a drain pipe 5 fixedly connected to the bottom of the plate flue gas cooler 4.

[0036] A conveying pump 6 is fixedly connected to the right end of the plate flue gas cooler 4. A deaerator 7 is fixedly connected to the bottom of the conveying pump 6. A water pump outlet pipe 8 is fixedly connected to the right end of the deaerator 7. A front flue gas duct 9 is fixedly connected to the bottom of the plate flue gas cooler 4. The primary air of the rotary air preheater 1 is fixedly connected to the left end of the rotary air preheater 1. A primary hot air duct 11 is fixedly connected to the bottom of the primary air of the rotary air preheater 1. A first plate heater 12 is fixedly connected to the bottom of the primary hot air duct 11. A second primary hot air duct 13 is fixedly connected to the top of the primary air of the rotary air preheater 1. The secondary air of the rotary air preheater 1 is fixedly connected to the left end of the rotary air preheater 1. The top of the rotary air preheater 1 is fixedly connected to a secondary hot air duct 15, the bottom of the rotary air preheater 1 is fixedly connected to a secondary hot air duct 16, the bottom of the secondary hot air duct 16 is fixedly connected to a second plate heater 17, the bottom of the second plate heater 17 is fixedly connected to a secondary air outlet 18, a plate 19 is installed inside the rotary air preheater 1, the bottom of the secondary air outlet 18 is fixedly connected to a plate 19, an element box 21 is installed inside the rotary air preheater 1, a limiting support rod 22 is snapped onto the surface of the element box 21, a heat storage element plate 23 is snapped onto the inside of the limiting support rod 22, and an installation slot 24 is opened inside the limiting support rod 22.

[0037] The combined rotary air preheater 1 and plate flue gas heat exchanger reduce the flue gas temperature at the boiler tail end from 370 degrees Celsius to approximately 80-120 degrees Celsius, maximizing the recovery of waste heat. The recovered waste heat heats the condensate, which is then recycled as a heat transfer medium. The plate air heat exchanger heats the primary and secondary air at the air preheater inlet, raising the primary cold air from -30 degrees Celsius to -180 degrees Celsius and the secondary cold air from -20 degrees Celsius to -160 degrees Celsius. The heated cold air then passes through the rotary air preheater 1, raising the primary air temperature to -340 degrees Celsius and the secondary air temperature to -320 degrees Celsius, thus achieving the recovery of waste heat from the flue gas.

[0038] A first plate heater 12 is fixedly connected to the left end of the plate flue gas cooler 4, and a second plate heater 17 is fixedly connected to the left end of the first plate heater 12.

[0039] After the flue gas is discharged from the boiler denitrification equipment, the temperature is about 370 degrees Celsius. Then it passes through the rotary air preheater 1. Remote temperature and pressure measuring points are set at the inlet and outlet flue of the rotary air preheater 1 to monitor the flue gas temperature and flue gas side resistance. After passing through the rotary air preheater 1, the flue gas temperature is about 220 degrees Celsius, ensuring that the wall temperature of the heat transfer element is higher than the acid dew point of the flue gas and avoiding ash accumulation on the heat transfer element. The flue gas discharged from the rotary air preheater 1 then passes through the plate flue gas cooler 4. The plate flue gas cooler 4 is modularly arranged, and each module is independent and can operate independently. Individual modules can be dry-burned by water-side isolation. At the same time, modules can be repaired and replaced. The flue gas temperature can be adjusted by adjusting the water flow of the plate flue gas cooler 4 to ensure that the outlet flue gas temperature of the plate heat exchanger can be maintained at about 80 degrees Celsius under different operating conditions.

[0040] The bottom of the second plate heater 17 is fixedly connected to a deaerator 7, the bottom of the first plate heater 12 is fixedly connected to a deaerator 7, and the bottom of the plate flue gas cooler 4 is fixedly connected to a deaerator 7.

[0041] Cold air is discharged from the primary and secondary fans. After passing through the fans, the air temperature is about 20 to 30 degrees Celsius. Then it passes through the plate air heaters, which are modularly arranged and can be isolated. After passing through the plate air heaters, the air temperature is raised to about 160 to 180 degrees Celsius. Then it enters the rotary air preheater 1. The higher inlet air temperature ensures that the average wall temperature of the cold end elements of the rotary air preheater 1 is higher than the acid dew point of the flue gas, avoiding ash accumulation on the heat transfer elements. After passing through the rotary air preheater, the air temperature of the primary and secondary air is raised to about 320 to 340 degrees Celsius. Then the primary air is conditioned and enters the coal mill, and the secondary air enters the furnace.

[0042] A delivery pump 6 is fixedly connected to the top of the water pump outlet pipe 8, and the delivery pump 6 is located at the bottom of the rotary air preheater 1.

[0043] The entire boiler flue gas coupling system based on the combined air preheater is a closed-loop system. The circulating water is taken from the mixed water at the No. 8 low-pressure inlet and the No. 7 low-pressure outlet. A regulating valve is installed at the No. 8 low-pressure inlet to adjust the water flow rate according to the mixed water temperature, ensuring that the mixed water temperature reaches 70 degrees Celsius. The mixed condensate is pressurized by the circulating water pump and then flows through the plate flue gas cooler 4. The high-temperature flue gas heats the condensate to ~220 degrees Celsius. After flowing through the plate flue gas cooler 4, it is divided into three branches, each flowing to the primary... The system includes a plate-type air heater, a secondary air plate-type air heater, and a plate-type air heater bypass. A regulating valve is installed at the outlet of the plate-type air heater to adjust the flow rate to the primary and secondary air plate-type air heaters according to the different temperature requirements of the primary and secondary air, thereby adjusting the air temperature. After passing through the plate-type air heater, the water temperature drops to ~90 degrees Celsius. The water flowing out of the plate-type air heater and the air heater bypass is mixed and returns to the water pump inlet to form a closed loop, or it can be directly returned to the condensate system.

[0044] The first plate heater 12 is located at the bottom of the primary air of the rotary air preheater 1, and the second plate heater 17 is located at the bottom of the secondary air of the rotary air preheater 1.

[0045] Drain pipe 5 is located at the left end of transfer pump 6 and at the top of deaerator 7.

[0046] The implementation principle of a boiler flue gas interconnection system using a combined air preheater in this application embodiment is as follows: A single positioning plate or corrugated plate is used, employing a combination of straight-channel large corrugations, oblique corrugations, and flat plates. The oblique corrugations between the straight-channel large corrugations and the flat plates form a 60-degree angle with the main axis and are arranged parallel to each other. The straight-channel large corrugations of plate type 19 correspond to the flat plates of plate type 20, forming ash passage channels to reduce the possibility of ash blockage. The oblique corrugations of plate type 19 and plate type 20 are arranged crosswise to increase airflow disturbance and improve heat exchange capacity. Heat storage element plates 23 are set using single-sided or double-sided finned plates with a thickness of 1-6 mm, arranged at a fixed pitch within the element box. The fins are machined, and their arrangement can be rationally configured according to the required heat exchange area. Each finned plate is positioned vertically... The edges are grooved and engage with the element box 21 to neatly arrange the heat storage elements. This ensures a constant gap between the heat storage element plates, with each element individually fixed and no contact or dead zones between them. The distance between the plates can be adjusted according to different project needs, ensuring heat exchange efficiency while maintaining the permeability of the heat storage elements for easy soot blowing. Heat transfer element plate type one and plate type two can be used individually or combined as hot-end and cold-end plates respectively. The plate heat exchanger is a high-efficiency heat exchange device constructed from corrugated metal plates. Heat transfer between fluids is achieved through closed channels between the plates. The plate heat exchanger described in this patent allows for selection of plates of different materials according to the operating temperature, making it widely applicable and highly corrosion-resistant. Employing fully automated, oxidation-free laser welding, the weld points are arranged in equilateral triangles. After welding, the plates are formed under high liquid pressure to create olive-shaped channels. The equilateral triangle weld points also enhance fluid turbulence as it passes through the plates, resulting in better heat exchange efficiency than traditional tubular heat exchangers. The flue gas channel is designed as a fully continuous channel, with the airflow direction essentially parallel to the heat exchange surface. Ash particles in the flue gas flow parallel to the plate surface, minimizing wear. The water-side channel is also olive-shaped with equilateral triangular flow, further enhancing heat exchange turbulence and efficiency. The plate heat exchanger uses a modular design, with each module equipped with an electric shut-off valve on the inlet and outlet water sides for independent dry-burning. Modular online dry-burning technology is employed to directionally remove ash accumulation from the plate heat exchanger, maintaining high system heat exchange efficiency. Furthermore, by adjusting the number of operating modules, the exhaust gas temperature can be flexibly controlled to adapt to different operating loads.

[0047] The above embodiments are merely preferred embodiments of this utility model and should not be construed as limiting the scope of protection of this utility model. Any non-substantial changes and substitutions made by those skilled in the art based on this utility model shall fall within the scope of protection claimed by this utility model.

Claims

1. A boiler flue gas interconnection system employing a combined air preheater, characterized in that, It includes a rotary air preheater (1), the top of which is fixedly connected to a flue gas inlet pipe (2), the bottom of which is fixedly connected to a flue gas outlet pipe (3), the bottom of which is fixedly connected to a plate flue gas cooler (4), and the bottom of which is fixedly connected to a drain pipe (5). The right end of the plate flue gas cooler (4) is fixedly connected to a delivery pump (6), the bottom of the delivery pump (6) is fixedly connected to a deaerator (7), the right end of the deaerator (7) is fixedly connected to a water pump outlet pipe (8), the bottom of the plate flue gas cooler (4) is fixedly connected to a front flue pipe (9), the left end of the rotary air preheater (1) is fixedly connected to a rotary air preheater primary air (10), the bottom of the rotary air preheater primary air (10) is fixedly connected to a primary warm air pipe one (11), the bottom of the primary warm air pipe one (11) is fixedly connected to a first plate heater (12), the top of the rotary air preheater primary air (10) is fixedly connected to a primary warm air pipe two (13), the left end of the rotary air preheater (1) is fixedly connected to a rotary air preheater secondary air (14), and the return The top of the secondary air (14) of the rotary air preheater is fixedly connected to a secondary hot air pipe (15), the bottom of the rotary air preheater (1) is fixedly connected to a secondary hot air pipe (16), the bottom of the secondary hot air pipe (16) is fixedly connected to a second plate heater (17), the bottom of the second plate heater (17) is fixedly connected to a secondary air outlet (18), a plate type (19) is installed inside the rotary air preheater (1), the bottom of the secondary air outlet (18) is fixedly connected to a plate type (19), an element box (21) is installed inside the rotary air preheater (1), a limiting support rod (22) is snapped onto the surface of the element box (21), a heat storage element plate (23) is snapped onto the inside of the limiting support rod (22), and an installation slot (24) is opened inside the limiting support rod (22).

2. A boiler flue gas interconnection system using a combined air preheater as described in claim 1, characterized in that: The left end of the plate flue gas cooler (4) is fixedly connected to a first plate heater (12), and the left end of the first plate heater (12) is fixedly connected to a second plate heater (17).

3. A boiler flue gas interconnection system using a combined air preheater as described in claim 1, characterized in that: The bottom of the second plate heater (17) is fixedly connected to a deaerator (7), the bottom of the first plate heater (12) is fixedly connected to a deaerator (7), and the bottom of the plate flue gas cooler (4) is fixedly connected to a deaerator (7).

4. A boiler flue gas interconnection system using a combined air preheater as described in claim 1, characterized in that: A delivery pump (6) is fixedly connected to the top of the water pump outlet pipe (8), and the delivery pump (6) is located at the bottom of the rotary air preheater (1).

5. A boiler flue gas interconnection system using a combined air preheater as described in claim 1, characterized in that: The first plate heater (12) is located at the bottom of the primary air (10) of the rotary air preheater, and the second plate heater (17) is located at the bottom of the secondary air (14) of the rotary air preheater.

6. A boiler flue gas interconnection system using a combined air preheater as described in claim 1, characterized in that: The drain pipe (5) is located at the left end of the delivery pump (6) and at the top of the deaerator (7).

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