Air preheating boiler with built-in air duct

Abstract

The utility model discloses an air preheating boiler with a built-in air duct, which comprises a boiler body with a combustion chamber inside, the boiler body is provided with an air supply outlet and a flue which are communicated with the combustion chamber, the air supply outlet is connected with a combustion air supply mechanism, and the flue is connected with an air preheater through a heat exchanger; an air supply mechanism is connected between the combustion air supply mechanism and the air preheater and comprises a boiler rack and an air guide ring arranged on the boiler rack, and the air guide ring communicates with a hot air outlet of the air preheater through an air inlet pipe. And the air guide ring is communicated with an air suction opening of the combustion air supply mechanism through an air outlet pipe. The flue gas waste heat recovery device has the advantages that flue gas waste heat is recovered through the air preheater, and the boiler efficiency is improved; the built-in air duct is arranged in the outer shield, so that the heat dissipation loss of the air duct is reduced; the built-in air duct and the boiler rack are integrally manufactured, redundant space in a package is used as the air duct, field installation is not needed, the workload is reduced, the boiler installation occupied area is reduced, the integration degree is high, and the boiler is more attractive.

Description

Technical Field

[0001] The utility model belongs to the technical field of boilers and relates to an air preheating boiler with a built-in air duct. Background Art

[0002] A boiler is a mechanical device that uses the thermal energy of fuel or other energy sources to heat water into hot water or steam. The hot water or steam generated in the boiler can directly provide the required thermal energy for industrial production and people's lives, and can also be converted into mechanical energy through a steam power device. The air preheaters of existing air preheating boilers are mostly installed on-site, and their air ducts are mostly set outside the boiler. In order to ensure the air flow rate of the air duct, the floor space is often large, and the installation workload also increases accordingly. The air duct is completely exposed to the outside, which increases the heat dissipation loss. If the heat dissipation loss is to be reduced, the air duct needs to be insulated, which requires additional costs. The appearance of the air duct installed on site is simple and bloated, which creates a sense of separation from the image of the boiler and is not beautiful.

[0003] Therefore, there is an urgent need for an air preheating boiler with a built-in air duct that is easy to install, has low heat loss, and does not take up space. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the utility model is to provide an air preheating boiler with a built-in air duct, which is used to solve the problems of the existing air preheating boilers being cumbersome to install, large heat loss and large space occupied.

[0005] The utility model provides an air preheating boiler with a built-in air duct, characterized in that it comprises a boiler body with a combustion chamber inside, the boiler body is provided with an air supply port and a flue connected to the combustion chamber, the air supply port is connected to a combustion air supply mechanism, and the flue is connected to an air preheater through a heat exchanger; an air supply mechanism is connected between the combustion air supply mechanism and the air preheater, the air supply mechanism comprises a boiler frame and an air guide ring arranged on the boiler frame, the air guide ring is connected to the hot air outlet of the air preheater through an air inlet pipe, and the air guide ring is connected to the air suction port of the combustion air supply mechanism through an air outlet pipe.

[0006] Preferably, the air preheating boiler further comprises an outer shield, which is arranged outside the boiler body, the combustion air supply mechanism, the air supply mechanism and the heat exchanger.

[0007] Preferably, the air guide ring includes an air guide channel with a rectangular cross-section formed by welding steel plates, the air guide ring is respectively connected to an air inlet pipe and an air outlet pipe, the air inlet pipe has a first air inlet port and a first air outlet port that are interconnected, the first air outlet port is connected to the air guide channel of the air guide ring, the first air inlet port is directly opposite to the hot air outlet of the air preheater, the cross-section of the first air inlet port is equal to that of the hot air outlet, the first air inlet port is circumferentially provided with an outer flange, the outer flange is fixedly connected to the hot air outlet of the air preheater by screws and a first connecting pipe; the air outlet pipe has a second air inlet port and a second air outlet port that are interconnected, the second air inlet port is connected to the air intake of the combustion air supply mechanism through a connecting pipe.

[0008] More preferably, the air guide ring is ring-shaped.

[0009] More preferably, a first outer flange is provided on the circumference of the first air inlet port, and a second outer flange is provided on the circumference of the hot air outlet of the air preheater, and the first outer flange is fixedly connected to the second outer flange by screws and a first connecting pipe.

[0010] Preferably, a boiler fixing frame is provided on the air guide ring, and the boiler body is installed on the boiler fixing frame.

[0011] Preferably, the air preheater is arranged on the boiler frame, and is provided with a flue gas inlet, a cold air inlet, a hot air outlet and a smoke exhaust port which are interconnected. The flue gas inlet is connected to the flue of the boiler body through a heat exchanger and a heat collecting box, and the hot air outlet is connected to the air inlet end of the air guide ring through a first connecting pipe and an air inlet pipe which are connected in sequence.

[0012] Preferably, the air preheater is a shell and tube heat exchanger, the interior of the air preheater is divided into an upper chamber, a first middle chamber, a second middle chamber and a lower chamber which are interconnected by two tube sheets and baffles arranged parallel to each other; a smoke exhaust port is provided at the top of the shell of the air preheater, a cold air inlet and a hot air outlet are provided on the side of the shell facing the boiler body, and a smoke inlet is provided at the bottom of the shell; the smoke exhaust port is connected to the upper chamber, the cold air inlet is connected to the first middle chamber, the hot air outlet is connected to the second middle chamber, and the smoke inlet is connected to the heat exchanger.

[0013] More preferably, a tube sheet is provided on each of the upper and lower sides of the baffle plate, and an air flow channel is left between the baffle plate and the shell wall of the air preheater to facilitate air circulation in the air preheater.

[0014] Preferably, a grille is provided at the cold air inlet.

[0015] Preferably, the combustion air supply mechanism includes a burner blower, which is arranged on the boiler frame. The burner blower has an air intake and an air outlet. The air intake of the burner blower is connected to the air guide ring through a damper and an air outlet pipe connected in sequence, and the air outlet of the burner blower is connected to the air supply port of the boiler body through a conveying pipeline system.

[0016] More preferably, the delivery pipeline system includes an air collecting box and multiple main delivery pipes, the bottom of the air collecting box is connected to the air outlet of the burner blower, and the side of the air collecting box is connected to each air supply port of the boiler body through multiple main delivery pipes; each of the main delivery pipes is provided with a gas delivery pipe with a control valve, and the gas delivery pipe is connected to a gas source.

[0017] Preferably, a filter is provided at the smoke inlet end of the heat exchanger.

[0018] When in use, the combustible gas is mixed with the hot air output by the burner fan through the conveying pipeline system and sent into the combustion chamber of the boiler body at the same time. The hot gas generated by the combustion of the combustible gas is discharged into the heat exchanger from the flue of the boiler body. The hot flue gas flows through the upper heat collecting box, the heat exchanger body and the lower heat collecting box in turn and enters the air preheater. At the same time, it exchanges heat with the cold air sent from the cold air inlet of the air preheater. The cold air is heated by the hot flue gas flow to form hot air. The hot air flows through the first connecting pipe, the air inlet pipe, the air guide ring, and the air outlet pipe in turn and is sent into the combustion air fan. Under the action of the burner fan, the hot air is mixed with the combustible gas again through the conveying pipeline system to complete the heat recovery. When the boiler frame of the present application is manufactured, the air guide ring and the boiler frame are integrated at the same time, and the excess space in the package is used as the air duct to support the boiler. At the same time, sufficient air channels are reserved to minimize the wind resistance of the air duct. No on-site installation is required, which not only reduces the workload of on-site installation, but also reduces the floor space occupied by the boiler installation. It has high integration and is more beautiful. When the boiler leaves the factory, the air supply mechanism is provided with a connection port that is the smoke outlet of the lower collector box at the rear of the boiler body and the first air inlet port of the air supply mechanism. During on-site installation, the smoke outlet is directly connected to the smoke inlet at the bottom of the air preheater, and the first air inlet port of the air inlet pipe is connected to the hot air outlet of the air preheater through a matching first connecting pipe. The above connections are all bolted connections, without the need for welding, which is simple and convenient.

[0019] The beneficial effects of the utility model are: recovering flue gas waste heat through the air preheater to improve boiler efficiency; the built-in air duct is arranged inside the outer shield to reduce heat dissipation loss in the air duct; the built-in air duct is manufactured in an integrated manner with the boiler frame, and the excess space in the package is used as the air duct, and no on-site installation is required, which not only reduces the on-site installation workload, but also reduces the installation area of ​​the boiler, with high integration and more beautiful appearance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is one of the structural schematic diagrams of an embodiment of the utility model.

[0021] Figure 2 This is the second structural schematic diagram of an embodiment of the utility model.

[0022] Figure 3 It is a front view of an embodiment of the utility model.

[0023] Figure 4 It is a rear view of an embodiment of the utility model.

[0024] Figure 5 It is a top view of an embodiment of the utility model.

[0025] Figure 6 It is a left side view of an embodiment of the utility model.

[0026] Figure 7 It is a right side view of an embodiment of the utility model.

[0027] Figure 8 It is a structural schematic diagram of another embodiment of the utility model.

[0028] Fig. 9 It is a structural schematic diagram of another embodiment of the utility model in which an air preheater is removed.

[0029] Fig.10 It is a structural schematic diagram of the third embodiment of the utility model, in which two sets of heat exchangers are provided.

[0030] Fig.11 It is a structural schematic diagram of the third embodiment of the utility model with the outer shield removed.

[0031] Fig.12 It is a structural schematic diagram of the air supply mechanism of the utility model.

[0032] Fig.13 It is a front view of the air supply mechanism of the utility model.

[0033] Fig.14 It is a right side view of the air supply mechanism of the utility model.

[0034] Fig.15 It is a left side view of the air supply mechanism of the utility model.

[0035] Fig.16 It is a structural diagram of the air preheater of the utility model.

[0036] Fig.17 It is an internal structure diagram of the air preheater of the utility model.

[0037] Among them, 1. boiler body; 11. air supply port; 12. flue; 13. heat exchanger; 131. heat exchanger body; 132. upper heat collecting box; 1321. cover; 133. smoke outlet; 2. combustion air supply mechanism; 21. burner fan; 211. air intake port; 212. air outlet; 22. conveying pipeline system; 221. air collecting box; 222. main conveying pipe; 223. gas pipe; 3. air preheater; 31. flue gas inlet; 32. cold air inlet; 33. hot air outlet; 34. flue gas outlet; 35. tube sheet; 36. baffle; 37. inspection port; 4. air supply mechanism; 41. boiler frame; 42. air guide ring; 43. air inlet pipe; 44. air outlet pipe; 45. first connecting pipe; 46. damper; 47. boiler fixing frame; 5. outer protective cover. DETAILED DESCRIPTION

[0038] The following describes the implementation of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application.

[0039] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0040] In addition, it should be understood that one or more method steps mentioned in this application do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in this application does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these two explicitly mentioned devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of implementation of this application. Changes or adjustments in their relative relationships shall also be regarded as the scope of implementation of this application without substantial changes in the technical content.

[0041] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0042] In the description of the present application, it should be understood that the terms "upper", "lower", "left", "right", "inner", "outer", "axial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, "multiple" means two or more.

[0043] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0045] The present application is further described below in conjunction with specific embodiments, but the protection scope of the present application is not limited thereto.

[0046] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present invention does not exclude the existence of other devices / apparatuses before and after the combination device / apparatus or the insertion of other devices / apparatuses between these explicitly mentioned two devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of implementation of the present invention. Changes or adjustments in their relative relationships shall also be regarded as the scope of implementation of the present invention without substantial changes in the technical content.

[0047] The utility model provides an air preheating boiler with a built-in air duct, comprising a boiler body 1 with a combustion chamber inside, the boiler body 1 is provided with an air supply port 11 and a flue 12 connected to the combustion chamber, the air supply port 11 is connected to a combustion air supply mechanism 2, and the flue 12 is connected to an air preheater 3 through a heat exchanger 13; an air supply mechanism 4 is connected between the combustion air supply mechanism 2 and the air preheater 3, the air supply mechanism 4 comprises a boiler frame 41 and an air guide ring 42 arranged on the boiler frame, the air guide ring 42 is connected to the hot air outlet of the air preheater 3 through an air inlet pipe 43, and the air guide ring 42 is connected to the air intake port of the combustion air supply mechanism 2 through an air outlet pipe 44.

[0048] In some embodiments of the present invention, the air preheating boiler further includes an outer protective cover 5 , which is arranged outside the boiler body 1 , the combustion air supply mechanism 2 , the air supply mechanism 4 and the heat exchanger 13 .

[0049] In some embodiments of the utility model, the air guide ring 42 is annular, including an air guide channel with a rectangular cross section formed by welding steel plates, the air guide ring 42 is respectively connected to the air inlet pipe 43 and the air outlet pipe 44, the air inlet pipe 43 has a first air inlet port and a first air outlet port that are interconnected, the first air outlet port 431 is connected to the air guide channel of the air guide ring 42, the first air inlet port is directly opposite to the hot air outlet of the air preheater 3, and the cross section of the first air inlet port is equal to that of the hot air outlet; the first air inlet port is fixedly connected to the hot air outlet of the air preheater 3 through a first connecting pipe 45; the air outlet pipe 44 has a second air inlet port and a second air outlet port that are interconnected, and the second air inlet port is connected to the air intake port of the combustion air supply mechanism 2 through a damper 46. It should be noted that the structure of the air guide ring 42 is not limited to a ring shape, and other structures that can achieve ventilation function are all acceptable.

[0050] In some embodiments of the utility model, a first outer flange is provided on the circumference of the first air inlet port, and a second outer flange is provided on the circumference of the hot air outlet of the air preheater 3, and the first outer flange is fixedly connected to the second outer flange by screws and a first connecting pipe 45. For the convenience of installation, the first connecting pipe can be connected with a hose such as a square bellows, which is convenient for adjusting the length and angle of the connecting pipe. The cross-section of the square bellows is rectangular, and connecting flanges are correspondingly provided at both ends of the square bellows. The outer edge of the connecting flange is provided with a plurality of mounting ears with threaded holes. When installing, it is only necessary to align the two ends of the square bellows with the first air inlet port and the hot air outlet respectively, and then tighten them with screws. The whole installation process is convenient and quick, and can adapt to air preheaters of different models.

[0051] In some embodiments of the utility model, a boiler fixing frame 47 is provided on the air guide ring 42, and the boiler body 1 is installed on the boiler fixing frame 47. The air guide ring 42 of the air supply mechanism is manufactured in an integrated manner with the boiler frame, and the extra space in the package is used as an air duct. The air guide ring 42, as a part of the boiler frame, can not only support the boiler, but also retain sufficient air channels, minimize the wind resistance of the air duct, and do not require on-site installation, thereby reducing the workload of on-site installation and the area occupied by the boiler installation. It has a high degree of integration and is more beautiful.

[0052] In some embodiments of the utility model, the air preheater 3 is arranged on the boiler frame 41, and is provided with a smoke inlet 31, a cold air inlet 32, a hot air outlet 33 and a smoke exhaust port 34 which are interconnected. The smoke inlet 31 is connected to the flue 12 of the boiler body 1 through the heat exchanger 13, and the hot air outlet 33 is connected to the air inlet end of the air guide ring 42 through a first connecting pipe 45 and an air inlet pipe 43 which are connected in sequence.

[0053] In some embodiments of the present invention, the heat exchanger 13 includes an upper heat collecting box 132, a heat exchanger body 131 and a smoke outlet 133 which are connected in sequence, the upper heat collecting box 132 is connected to the flue 12 of the boiler body 1, and the smoke outlet 133 is connected to the smoke inlet 31 of the air preheater 3.

[0054] In some embodiments of the present invention, an inspection hole is provided on the top of the upper heat collecting box 132, and a cover 1321 is detachably provided at the inspection hole.

[0055] In some embodiments of the present invention, a filter is disposed at the smoke inlet end of the heat exchanger body 131 .

[0056] In some embodiments of the utility model, the air preheater 3 is a shell and tube heat exchanger, and the interior of the air preheater 3 is divided into an upper chamber, a first middle chamber, a second middle chamber and a lower chamber that are interconnected by multiple tube sheets 35 and baffles 36 arranged in parallel to each other; a smoke exhaust port 34 is provided at the top of the shell of the air preheater 3, a cold air inlet 32 ​​and a hot air outlet 33 are provided on the side of the shell facing the boiler body 1, and a smoke inlet 31 is provided at the bottom of the shell; the smoke exhaust port 34 is connected to the upper chamber, the cold air inlet 32 ​​is connected to the first middle chamber, the hot air outlet 33 is connected to the second middle chamber, and the smoke inlet 31 is connected to the heat exchanger 13.

[0057] In some embodiments of the utility model, a tube sheet 35 is provided on each of the upper and lower sides of the baffle plate 36 , and an air flow channel is left between the baffle plate 36 and the shell wall of the air preheater 3 .

[0058] In some embodiments of the present invention, a smoke outlet hole opening upward is provided on one side of the smoke outlet 133 , and the smoke outlet hole is connected to the smoke inlet 31 .

[0059] In some embodiments of the present invention, a grille is disposed at the cold air inlet 32 ​​.

[0060] In some embodiments of the present invention, an inspection port 37 is provided on the upper portion of the air preheater 3 to facilitate inspection and maintenance of the air preheater.

[0061] In some embodiments of the utility model, the combustion air supply mechanism 2 includes a burner blower 21, which is arranged on the boiler frame 41, and has an air intake port 211 and an air outlet 212. The air intake port 211 of the burner blower 21 is connected to the air guide ring through a damper 46 and an air outlet pipe 44 connected in sequence, and the air outlet of the burner blower is connected to the air supply port 11 of the boiler body 1 through a conveying pipeline system 22.

[0062] In some embodiments of the utility model, the delivery pipeline system 22 includes an air collecting box 221 and multiple main delivery pipes 222. The bottom of the air collecting box 221 is connected to the air outlet of the burner blower 21, and the side of the air collecting box 221 is connected to the air supply port 11 of the boiler body 1 through multiple main delivery pipes 222; each of the main delivery pipes 222 is provided with a gas delivery pipe 223 with a control valve, and the gas delivery pipe 223 is connected to the gas source.

[0063] When in use, the combustible gas is mixed with the hot air output by the burner fan 21 through the conveying pipeline system 22 and is sent into the combustion chamber of the boiler body 1 at the same time. The hot gas generated after the combustible gas is burned is discharged into the heat exchanger 13 from the flue of the boiler body 1. The hot flue gas flows through the upper heat collecting box 132, the heat exchanger body 131 and the smoke outlet 133 in turn and then enters the air preheater 3. At the same time, the cold air sent into the cold air inlet 32 ​​of the air preheater 3 forms hot air after heat exchange with the hot flue gas flow. The hot air flows through the first connecting pipe 45, the air inlet pipe 43, the air guide ring 42, and the air outlet pipe 44 in turn and then is sent into the combustion gas fan 21. Under the action of the burner fan 21, the hot air is mixed with the combustible gas again through the conveying pipeline system 22 to complete the heat recovery. When manufacturing the boiler frame of the present application, the air guide ring and the boiler frame are integrated at the same time, and the extra space in the package is used as an air duct to support the boiler. At the same time, sufficient air channels are retained to minimize the wind resistance of the air duct. No on-site installation is required, which not only reduces the workload of on-site installation, but also reduces the floor space occupied by the boiler installation. The integration is high and more beautiful. When the boiler leaves the factory, the air supply mechanism is provided with a connection port for the smoke outlet 133 at the tail of the boiler body and the first air inlet port of the air supply mechanism. During on-site installation, the smoke outlet is directly connected to the smoke inlet 31 at the bottom of the air preheater 3, and the first air inlet port of the air inlet pipe 43 is connected to the hot air outlet 33 of the air preheater 3 through the matching first connecting pipe 45. The above connections are all bolted connections, without the need for welding, which is simple and convenient.

[0064] The above examples are intended to illustrate the embodiments disclosed in the present utility model and should not be construed as limitations on the present utility model. In addition, the various modifications listed herein and the changes in the methods and compositions in the utility model are obvious to those skilled in the art without departing from the scope and spirit of the present utility model. Although the present utility model has been specifically described in conjunction with a variety of specific preferred embodiments of the present utility model, it should be understood that the present utility model should not be limited to these specific embodiments. In fact, various modifications as described above that are obvious to those skilled in the art to obtain the utility model should be included in the scope of the present utility model.

Claims

1. An air preheating boiler with a built-in air duct, characterized in that: It includes a boiler body with a combustion chamber inside, the boiler body is provided with an air supply port and a flue connected to the combustion chamber, the air supply port is connected to a combustion air supply mechanism, and the flue is connected to an air preheater through a heat exchanger; an air supply mechanism is connected between the combustion air supply mechanism and the air preheater, the air supply mechanism includes a boiler frame and an air guide ring arranged on the boiler frame, the air guide ring is connected to the hot air outlet of the air preheater through an air inlet pipe, and the air guide ring is connected to the air intake port of the combustion air supply mechanism through an air outlet pipe.

2. The air preheating boiler with built-in air duct according to claim 1, characterized in that: The air preheating boiler further comprises an outer protective cover, which is arranged outside the boiler body, the combustion air supply mechanism, the air supply mechanism and the heat exchanger.

3. The air preheating boiler with built-in air duct according to claim 1, characterized in that: The air guide ring includes an air guide channel with a rectangular cross-section formed by welding steel plates, and the air guide ring is respectively connected to an air inlet pipe and an air outlet pipe, and the air inlet pipe has a first air inlet port and a first air outlet port that are interconnected, and the first air outlet port is connected to the air guide channel of the air guide ring, and the first air inlet port is directly opposite to the hot air outlet of the air preheater, and the cross-section of the first air inlet port is equal to that of the hot air outlet, and the first air inlet port is fixedly connected to the hot air outlet of the air preheater through a first connecting pipe; the air outlet pipe has a second air inlet port and a second air outlet port that are interconnected, and the second air inlet port is connected to the air intake port of the combustion air supply mechanism through a damper.

4. The air preheating boiler with built-in air duct according to claim 3, characterized in that: A first outer flange is arranged around the first air inlet port, and a second outer flange is arranged around the hot air outlet of the air preheater. The first outer flange is fixedly connected to the second outer flange through screws and a connecting pipe.

5. The air preheating boiler with built-in air duct according to claim 1, characterized in that: A boiler fixing frame is arranged on the air guide ring, and the boiler body is installed on the boiler fixing frame.

6. The air preheating boiler with built-in air duct according to claim 1, characterized in that: The air preheater is arranged on the boiler frame, and is provided with a smoke inlet, a cold air inlet, a hot air outlet and a smoke exhaust port which are interconnected. The smoke inlet is connected to the flue of the boiler body through a heat exchanger, and the hot air outlet is connected to the air inlet end of the air guide ring through a first connecting pipe and an air inlet pipe which are connected in sequence.

7. The air preheating boiler with built-in air duct according to claim 6, characterized in that: The air preheater is a shell and tube heat exchanger, and the interior of the air preheater is divided into an upper chamber, a middle chamber and a lower chamber that are interconnected by a plurality of filter plates and baffles arranged in parallel to each other; a smoke exhaust port is provided at the top of the shell of the air preheater, a cold air inlet and a hot air outlet are provided on the side of the shell facing the boiler body, and a smoke inlet is provided at the bottom of the shell; the cold air inlet and the smoke exhaust port are connected to the upper chamber, the hot air outlet is connected to the middle chamber, and the smoke inlet is connected to the heat exchanger.

8. The air preheating boiler with built-in air duct according to claim 1, characterized in that: The combustion air supply mechanism includes a burner blower, which is arranged on the boiler frame. The burner blower has an air intake and an air outlet. The air intake of the burner blower is connected to the air guide ring through a second connecting pipe and an air outlet pipe connected in sequence, and the air outlet of the burner blower is connected to the air supply port of the boiler body through a conveying pipeline system.

9. The air preheating boiler with built-in air duct according to claim 8, characterized in that: The delivery pipeline system includes an air collecting box and multiple main delivery pipes. The bottom of the air collecting box is connected to the air outlet of the burner blower, and the side of the air collecting box is connected to each air supply port of the boiler body through multiple main delivery pipes; each main delivery pipe is equipped with a gas delivery pipe with a control valve, and the gas delivery pipe is connected to the gas source.

10. The air preheating boiler with built-in air duct according to claim 6, characterized in that: The smoke inlet end of the heat exchanger is provided with a filter.

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