Structure for preventing low-temperature corrosion of air pre-heater

Abstract

The utility model relates to the field of boiler air pre-heaters, in particular to a structure for preventing low-temperature corrosion of an air pre-heater, which comprises an air pre-heater pipe, a pipe plate, a side plate and a flow guide component, the plurality of air pre-heater pipes are vertically arranged in an array, and are used for introducing high-temperature flue gas; the two tube plates are respectively connected with the top ends and the bottom ends of the plurality of air pre-heater tubes; the two side plates and the two tube plates are connected to form an air channel with a rectangular section, the air pre-heater tubes are all located in the air channel, and the air inlet direction of the air pre-heater tubes is orthogonal to the air inlet direction of the air channel. The flow guide assembly is arranged on the pipe plate close to one side of the exhaust port of the air pre-heater pipe and located on one side of the air inlet in the air duct, and the flow guide assembly is used for shielding the ends, close to the exhaust port, of the air pre-heater pipes on one side of the air inlet in the air duct. The air pre-heater has the advantages that the air outlet end of the air pre-heater pipe on one side of the air inlet is shielded by arranging the flow guide assembly, so that the air pre-heater pipe is prevented from being corroded due to smoke condensation caused by low temperature of the air pre-heater pipe.

Description

Technical Field

[0001] The utility model relates to the field of boiler air preheaters, in particular to a structure for preventing low-temperature corrosion of air preheaters. Background Art

[0002] Air preheater, also referred to as air preheater, is a preheating device that improves boiler heat exchange performance and reduces heat loss. The function of the air preheater is to transfer the heat carried by the flue gas discharged from the tail flue of the boiler to the air before entering the boiler, and preheat the air to a certain temperature.

[0003] During the operation of the tube-box air preheater, the temperature of the high-temperature flue gas after entering the air preheater and undergoing heat exchange becomes lower and lower, while the temperature of the air after entering the air preheater and undergoing heat exchange becomes higher and higher. The lowest temperature position on the air preheater is formed at the overlapping position of the air inlet position and the flue gas outlet position of the air preheater, forming a low-temperature hot surface; when the fuel is burning, a large amount of water vapor is contained in the flue gas. In addition, the sulfur in the fuel generates sulfur dioxide after combustion, of which a small amount of SO2 is further oxidized into sulfur trioxide, which combines with the water vapor in the flue gas to generate sulfuric acid. When the flue gas containing sulfuric acid vapor reaches the low-temperature hot surface position, the temperature is lower than the dew point, causing the sulfuric acid vapor to condense in the air preheater, causing serious corrosion of the heating surface, and then causing the metal of the air preheater heating surface to rupture and perforate, causing a large amount of air to leak into the flue gas, resulting in insufficient air supply and reduced boiler thermal efficiency. Utility Model Content

[0004] The utility model aims to overcome the shortcomings of the prior art and provide a structure for preventing low-temperature corrosion of an air preheater.

[0005] The purpose of the utility model is achieved through the following technical solutions: a structure for preventing low-temperature corrosion of an air preheater, comprising an air preheater tube, a tube sheet, a side plate and a guide assembly; a plurality of air preheater tubes are arranged in a vertical array, and the air preheater tubes are used to pass high-temperature flue gas; two tube sheets are respectively connected to the top and bottom ends of the plurality of air preheater tubes; the two side plates are connected to the two tube sheets to form an air duct with a rectangular cross-section, the air preheater tubes are all located in the air duct, and the air inlet direction of the air preheater tubes is arranged orthogonally to the air inlet direction of the air duct; the guide assembly is arranged on the tube sheet on one side of the exhaust port of the air preheater tube and is located on one side of the air inlet in the air duct, and the guide assembly is used to shield one end of the plurality of air preheater tubes located on the air inlet side of the air duct close to the exhaust port.

[0006] In the utility model, high-temperature flue gas is introduced into the air preheater tube to increase the temperature of the air preheater tube, the air preheater tube is arranged in the air duct, air is introduced into the air duct, and the air is heated by the high-temperature air preheater tube; the air temperature at the air inlet of the air duct is the lowest, therefore, the temperature of the air preheater tube located at the air inlet of the air duct drops the most, and the temperature at the exhaust port end of the air preheater tube at the air inlet of the air duct is the lowest, the guide component is arranged here, the air preheater tube here is shielded, the air preheater tube here is prevented from contacting with cold air, and the flue gas temperature in the air preheater tube here is prevented from dropping below the dew point.

[0007] In some embodiments, the tube sheet is provided with a plurality of openings corresponding to the air preheater tubes, and the ends of the air preheater tubes are inserted into and connected to the openings. The openings on the tube sheet are used to position the air preheater tubes, while leaving positions for the air inlet and the air outlet of the air preheater tubes.

[0008] In some embodiments, the guide assembly includes a windshield, the bottom end of which is connected to one end of the tube sheet near the air inlet of the air duct, and the windshield forms a projection surface with a height of 300mm-500mm on the cross section of the air duct. The windshield blocks the end of the air preheater tube near the exhaust port at the air inlet of the air duct to prevent cold air from directly contacting the air preheater tube there.

[0009] In some embodiments, the guide assembly further includes a guide plate, the top end of the wind shield is connected to the head end of the guide plate, the guide plate is arranged along the wind duct direction and forms an angle of 5°-30° with the horizontal plane, the tail end height of the guide plate is lower than the head end height, and a plurality of the air preheater tubes pass through the guide plate. The guide plate is arranged to prevent the cold air from forming a vortex on the back of the wind shield after passing through the wind shield, and completely prevent the air preheater tubes behind the wind shield from contacting the cold air.

[0010] In some embodiments, the guide assembly further comprises a support plate, the top of the support plate is connected to the tail end of the guide plate, the bottom of the support plate is connected to the tube plate, and the support plate is used to support the guide plate. The support plate is used to support the guide plate to make the guide plate more stable.

[0011] In some embodiments, a closed heat preservation cavity is formed between the tube plate, the wind shield, the guide plate, the support plate and the two side plates. The closed heat preservation cavity isolates the air inside and outside, further preventing the air preheater tube behind the wind shield from being cooled by cold air.

[0012] In some embodiments, the heat preservation cavity is filled with heat preservation material, which enhances the heat preservation effect and further prevents the air preheater tube behind the windshield from being cooled.

[0013] In some embodiments, an enamel anti-corrosion layer is provided on the inner wall of the air preheater tube. The enamel anti-corrosion layer improves the corrosion resistance of the air preheater tube.

[0014] In some embodiments, an anti-vibration partition is provided between the two tube sheets along the air duct direction, and the anti-vibration partition separates the air duct. The anti-vibration partition improves the strength of the air duct and prevents the air duct from vibrating during operation.

[0015] The utility model has the following advantages:

[0016] The utility model arranges a flow guide component at the end of the air preheater tube near the exhaust port at the air inlet of the air duct to prevent the exhaust port end of the air preheater tube at the air inlet end of the air duct from being cooled by cold air, thereby preventing the flue gas in the air preheater tube from being cooled to below the dew point, and further preventing the flue gas from condensing in the air preheater tube and causing the air preheater tube to be corroded. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the internal structure of the structure for preventing low-temperature corrosion of an air preheater according to the utility model;

[0018] Figure 2 A top view of the structure for preventing low-temperature corrosion of an air preheater according to the utility model;

[0019] In the figure: 1. air preheater tube; 2. tube sheet; 31. wind shield; 32. guide plate; 33. support plate; 4. insulation chamber; 5. side plate; 6. anti-vibration partition. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model, that is, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. The components of the embodiments of the utility model described and shown in the drawings can be arranged and designed in various different configurations.

[0021] The present invention is further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

[0022] like Figure 1-Figure 2As shown, a structure for preventing low-temperature corrosion of an air preheater comprises an air preheater tube 1, a tube sheet 2, a side plate 5 and a guide assembly; a plurality of air preheater tubes 1 are arranged in a vertical array, and the air preheater tubes 1 are used to introduce high-temperature flue gas; two tube sheets 2 are respectively connected to the top and bottom ends of the plurality of air preheater tubes 1; the two side plates 5 are connected to the two tube sheets 2 to form an air duct with a rectangular cross-section, and the air preheater tubes 1 are all located in the air duct, and the air inlet direction of the air preheater tubes 1 is arranged orthogonally to the air inlet direction of the air duct; the guide assembly is arranged on the tube sheet 2 close to the exhaust port side of the air preheater tube 1 and is located on one side of the air inlet in the air duct, and the guide assembly is used to shield one end of the plurality of air preheater tubes 1 close to the exhaust port on one side of the air inlet in the air duct.

[0023] Specifically, in this embodiment, two tube sheets 2 are connected to two side sheets 5 to form an air duct with a rectangular cross-section. A plurality of air preheater tubes 1 are arranged in a vertical array in the air duct. The top and bottom of the air preheater tube 1 are respectively connected to the two tube sheets 2. The air inlet and the exhaust port at both ends of the air preheater tube 1 penetrate the tube sheets 2 and are located outside the air duct. The high-temperature flue gas enters the air preheater tube 1 from the air inlet of the air preheater tube 1 and is discharged from the air preheater tube 1 from the exhaust port. While the flue gas flows through the air preheater tube 1, cold air is introduced into the air duct. The cold air flows through the outer surface of the air preheater tube 1 to cool the air preheater tube 1, thereby cooling the flue gas in the air preheater tube 1. The cold air is heated to achieve the effect of preheating the air. It can be understood that the air temperature of the air preheater tube 1 flowing through the side of the air duct inlet is the lowest, and accordingly, the temperature of the air preheater tube 1 located on the side of the air duct inlet will drop the most; in the air preheater tube 1, since the flue gas is cooled by the air preheater tube 1, the temperature of the flue gas gradually decreases along the flow direction of the flue gas, and the flue gas temperature at the end of the air preheater tube 1 close to the exhaust port is the lowest; therefore, the end of the air preheater tube 1 located on the side of the air duct inlet close to the exhaust port is the lowest temperature point in the entire air preheater, and a guide component is provided here to shield this place and play a role in heat preservation, thereby preventing the lowest temperature point from being further cooled by the cold air from the air duct inlet, thereby preventing the flue gas temperature in the air preheater tube 1 from dropping below the dew point, and preventing the air preheater tube 1 from dew point corrosion.

[0024] Preferably, the tube sheet 2 is provided with a plurality of openings corresponding to the air preheater tube 1, and the end of the air preheater tube 1 is inserted into and connected to the opening. In this embodiment, the openings on the tube sheet 2 are used to position and fix the air preheater tube 1, and the outer surface of the air preheater tube 1 is welded to the edge of the opening.

[0025] Preferably, the guide assembly includes a windshield 31, the bottom end of the windshield 31 is connected to one end of the tube sheet 2 close to the air inlet of the air duct, and the windshield 31 forms a projection surface with a height of 300mm-500mm on the cross section of the air duct. Specifically, in the present embodiment, the bottom end of the windshield 31 is welded to one end of the tube sheet 2 at one end of the exhaust port of the air preheater tube 1 close to the air inlet of the air duct, and an acute angle is formed between the windshield 31 and the tube sheet 2. Both sides of the windshield 31 are welded to the two side plates 5 respectively, and the windshield 31 forms a projection surface with a height of 300mm-500mm on the cross section of the air duct, blocking part of the cold air, preventing the cold air from flowing through the lowest temperature of the air preheater, achieving the effect of heat preservation, and thus avoiding the dew point corrosion of the air preheater tube 1.

[0026] Preferably, the guide assembly also includes a guide plate 32, the top end of the wind shield 31 is connected to the head end of the guide plate 32, the guide plate 32 is arranged along the wind duct direction and forms an angle of 5°-30° with the horizontal plane, the tail end height of the guide plate 32 is lower than the head end height, and a plurality of the air preheater tubes 1 pass through the guide plate 32.

[0027] In this embodiment, after the cold air flows through the wind shield 31, a vortex will be formed on the back of the wind shield 31. The vortex will cool the air preheater tube 1 on the back of the wind shield 31, weakening the wind shielding effect of the wind shield 31. Therefore, a guide plate 32 is arranged on the top of the wind shield 31 to prevent the cold air from forming a vortex after flowing through the wind shield 31, thereby preventing the cold air from contacting the air preheater tube 1 on the back of the wind shield 31, thereby achieving a better insulation effect. The guide plate 32 is made to form an angle of 5°-30° with the horizontal plane, and the height of the tail end of the guide plate 32 is lower than the height of the head end of the guide plate 32, so as to reduce the gap between the tail end of the guide plate 32 and the tube sheet 2, so as to reduce the vortex formed when the cold air flows through the tail end of the guide plate 32, thereby avoiding reducing the insulation effect. A plurality of through holes are arranged on the guide plate 32 corresponding to the air preheater tube 1, and the air preheater tube 1 passes through the guide plate 32 through the through holes, and the outer surface of the air preheater tube 1 is welded to the edge of the through hole. Both sides of the guide plate 32 are respectively welded to the two side plates 5 .

[0028] Preferably, the guide assembly further includes a support plate 33, the top of the support plate 33 is connected to the tail end of the guide plate 32, the bottom of the support plate 33 is connected to the tube sheet 2, and the support plate 33 is used to support the guide plate 32. The two ends of the support plate 33 are respectively welded to the tube sheet 2 and the guide plate 32 to support the guide plate 32, and the two sides of the support plate 33 are welded to the two side plates 5.

[0029] Preferably, a closed heat preservation chamber 4 is formed between the tube sheet 2, the wind shield 31, the guide plate 32, the support plate 33 and the two side plates 5. The heat preservation chamber 4 is a closed space, which is isolated from the air in the air duct, avoids heat exchange between the air inside and outside the heat preservation chamber 4, and improves the heat preservation effect.

[0030] Preferably, the heat preservation cavity 4 is filled with heat preservation material, which further improves the heat preservation effect.

[0031] Preferably, an enamel anti-corrosion layer is provided on the inner wall of the air preheater tube 1. The enamel anti-corrosion layer improves the anti-corrosion effect of the air preheater tube 1 and prolongs the service life of the air preheater.

[0032] Preferably, an anti-vibration partition plate 6 is arranged between the two tube sheets 2 along the air duct direction, and the anti-vibration partition plate 6 divides the air duct. The anti-vibration partition plate 6 is arranged along the air duct to divide the air duct into small air ducts, thereby improving the strength of the air duct, avoiding vibration during operation, and extending the life of the air preheater.

[0033] The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Any technician familiar with the field can make many possible changes and modifications to the technical solution of the utility model by using the above-mentioned technical content without departing from the scope of the technical solution of the utility model, or modify it into an equivalent embodiment of equivalent changes. Therefore, any changes, modifications, equivalent changes and modifications made to the above embodiments based on the technology of the utility model without departing from the content of the technical solution of the utility model shall fall within the protection scope of the technical solution of the utility model.

Claims

1. A structure for preventing low temperature corrosion of an air preheater, characterized in that: include: An air preheater tube (1), wherein a plurality of the air preheater tubes (1) are arranged in a vertical array, and the air preheater tubes (1) are used to pass high-temperature flue gas; Tube sheets (2), two tube sheets (2) are respectively connected to the top ends and bottom ends of a plurality of the air preheater tubes (1); side sheets (5), two side sheets (5) are connected to the two tube sheets (2) to form an air duct with a rectangular cross-section, the air preheater tubes (1) are all located in the air duct, and the air inlet direction of the air preheater tubes (1) is arranged orthogonally to the air inlet direction of the air duct; A flow guide component, the flow guide component is arranged on a tube plate (2) close to the exhaust port of the air preheater tube (1) and is located on one side of the air inlet in the air duct, and the flow guide component is used to shield one end of a plurality of air preheater tubes (1) located on the air inlet side in the air duct close to the exhaust port.

2. The structure for preventing low temperature corrosion of air preheater according to claim 1 is characterized in that: The tube sheet (2) is provided with a plurality of openings corresponding to the air preheater tubes (1), and the ends of the air preheater tubes (1) are inserted into the openings and connected to the openings.

3. The structure for preventing low temperature corrosion of air preheater according to claim 1 is characterized in that: The flow guide assembly comprises a wind shield (31), the bottom end of the wind shield (31) is connected to one end of the tube plate (2) close to the air inlet of the air duct, and the wind shield (31) forms a projection surface with a height of 300mm-500mm on the cross section of the air duct.

4. The structure for preventing low temperature corrosion of air preheater according to claim 3 is characterized in that: The guide assembly also includes a guide plate (32), the top end of the wind shield (31) is connected to the head end of the guide plate (32), the guide plate (32) is arranged along the wind duct direction and forms an angle of 5°-30° with the horizontal plane, the tail end height of the guide plate (32) is lower than the head end height, and a plurality of the air preheater tubes (1) pass through the guide plate (32).

5. The structure for preventing low temperature corrosion of air preheater according to claim 4 is characterized in that: The guide assembly further comprises a support plate (33), the top of the support plate (33) being connected to the rear end of the guide plate (32), the bottom of the support plate (33) being connected to the tube plate (2), and the support plate (33) being used to support the guide plate (32).

6. The structure for preventing low temperature corrosion of air preheater according to claim 5 is characterized in that: A closed heat-insulating chamber (4) is formed between the tube plate (2), the wind shield (31), the guide plate (32), the support plate (33) and the two side plates (5).

7. The structure for preventing low temperature corrosion of air preheater according to claim 6 is characterized in that: The heat-insulating cavity (4) is filled with heat-insulating material.

8. The structure for preventing low temperature corrosion of air preheater according to claim 1 is characterized in that: An enamel anti-corrosion layer is provided on the inner wall of the air preheater tube (1).

9. The structure for preventing low temperature corrosion of air preheater according to claim 1 is characterized in that: An anti-vibration partition plate (6) is arranged between the two tube plates (2) along the direction of the air duct, and the anti-vibration partition plate (6) separates the air duct.

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