Air preheater for increasing temperature of side wall at air inlet

Abstract

The utility model discloses an air preheater of improving air import side wall temperature belongs to the technical field of flue gas treatment equipment, solve the heat exchanger in the junction of flue gas export area and cold air import area because of the dust deposition causes the heating surface of heat exchanger to appear the abrasion, corrosion and the problem of block, the technical scheme of solving this problem mainly includes multiple heat exchange plates, and the heat exchange plate includes first thin plate and second thin plate, and the opposite two side edges of first thin plate and second thin plate are welded sealing, and the middle part is welded through multiple welding columns, and the position of not welding is mutually far away and forms air channel, and the flue gas channel is formed between two adjacent heat exchange plates, and the side of first thin plate and second thin plate and flue gas channel contact is equipped with the heat insulating member for reducing the heat exchange amount of heat exchange plate and flue gas in flue gas channel, and the heat insulating member is located the air inlet end of air channel, the utility model mainly effectively prevent ammonium bisulfate liquefaction deposition, reduce the dust deposition formation, improve the heat exchange efficiency and service life.

Description

Technical Field

[0001] This utility model relates to the technical field of flue gas treatment equipment, and in particular to an air preheater that increases the temperature of the air inlet sidewall. Background Technology

[0002] Air heat exchangers, as key equipment for preheating air in power plants, face serious ash accumulation problems in actual operation. Ammonium bisulfate, formed by the reaction of ammonia escaping from the denitrification system with sulfur trioxide and water vapor in the flue gas, liquefies and becomes viscous within a temperature range of 150-200℃. This viscous substance readily adheres to the surface of the heat exchanger's heat storage fins, thereby capturing fly ash particles from the flue gas and forming a stubborn ash layer. Ash accumulation not only significantly reduces heat exchange efficiency but also triggers a series of operational safety hazards.

[0003] The thermal resistance of ash deposits is much higher than that of metallic materials, and their presence significantly reduces the heat transfer performance of heat exchangers. More seriously, ash accumulation reduces the flow area of ​​flue gas passages, causing localized increases in flow velocity and exacerbating wear and corrosion of heated surfaces. Simultaneously, ash accumulation increases flue gas flow resistance, leading to higher exhaust gas temperatures and directly impacting the safe and stable operation of the boiler system.

[0004] In traditional heat exchangers, flue gas and cold air flow in a vertical, cross-flow pattern. This arrangement results in the lowest temperature at the junction of the flue gas outlet and the cold air inlet, which falls precisely within the critical temperature range for ammonium bisulfate liquefaction. This area therefore becomes the most prone to ash accumulation, leading to channel blockage after prolonged operation and severely impacting the equipment's heat exchange performance and lifespan. Utility Model Content

[0005] The purpose of this invention is to provide an air preheater that increases the temperature of the air inlet side wall, thereby solving the problem of wear, corrosion, and blockage of the heat exchanger's heating surface caused by ash accumulation at the junction of the flue gas outlet area and the cold air inlet area. This effectively prevents the liquefaction and deposition of ammonium bisulfate, reduces ash accumulation, and improves heat exchange efficiency and service life.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an air preheater for increasing the temperature of the air inlet sidewall, comprising a heat exchanger, the heat exchanger comprising multiple heat exchange plates arranged sequentially at intervals, each heat exchange plate comprising a first thin plate and a second thin plate, the opposite sides of the first and second thin plates being welded and sealed, the middle of the first and second thin plates being welded by multiple welding columns, the unwelded parts of the first and second thin plates being far apart from each other to form an air channel for airflow, the two ends of the first and second thin plates between adjacent air channels being sealed and connected, a flue gas channel being formed between adjacent heat exchange plates, and a heat insulation component for reducing the heat exchange between the heat exchange plates and the flue gas in the flue gas channel being provided on the side of the first and second thin plates in contact with the flue gas channel, the heat insulation component being located at the air inlet end of the air channel.

[0007] Furthermore, the length of the heat insulation element in the air passage direction gradually increases along the flue gas flow direction.

[0008] Furthermore, the heat insulation component includes two heat insulation plates, which are respectively attached to the heat-receiving surfaces of the first thin plate and the second thin plate to increase the thickness of the first thin plate and the second thin plate and reduce the heat exchange between the flue gas and the heat exchange plate.

[0009] Furthermore, the heat insulation plate is integrally formed on the heat-receiving surface of the heat exchange plate.

[0010] Furthermore, the heat insulation plate is welded to the heat exchange plate.

[0011] Furthermore, the thickness of the heat insulation plate gradually increases along the flue gas flow direction, and the width of the flue gas auxiliary channel gradually decreases along the flue gas flow direction.

[0012] Furthermore, the heat insulation component is a heat insulation coating, which is applied to the heated surfaces of the first and second thin plates.

[0013] Furthermore, it also includes a flue gas auxiliary duct, the tail end of which is connected to the air inlet end of the flue gas duct, and a guide plate is provided at the outlet end of the auxiliary flue gas duct, with the tail end of the guide plate extending to the air inlet end of the air duct.

[0014] Furthermore, multiple guide plates are provided, and the multiple guide plates are distributed at intervals. The distance between two adjacent guide plates at the outlet of the flue gas auxiliary pipe gradually decreases in the direction away from the heat exchange plate.

[0015] As can be seen from the above, this utility model reduces the heat exchange efficiency between flue gas and cold air at the junction of the flue gas outlet area and the cold air inlet area by setting a heat insulation component with a flue gas auxiliary channel in the flue gas channel at the air inlet end of the air channel, thereby increasing the temperature at the junction of the flue gas outlet area and the cold air inlet area, avoiding the liquefaction and adhesion of ammonium bisulfate, effectively preventing the formation of ash at the junction of the flue gas outlet area and the cold air inlet area of ​​the heat exchanger, improving heat exchange efficiency and operational safety. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings: Figure 1 This is a schematic diagram of an air preheater for increasing the temperature of the air inlet side wall according to the present invention; Figure 2 This is a schematic diagram of the heat exchange plate in this utility model. Figure 3 This is a schematic diagram of the first thin plate and the second thin plate in this utility model; Figure 4 This is a schematic diagram of the installation of the heat exchange plate and the heat insulation component in this utility model; Figure 5 This is a schematic diagram of the heat insulation plate in this utility model; Figure 6 This is a schematic diagram of the heat insulation component in this utility model. Figure 7 This is a schematic diagram of the flue gas duct and the flue gas auxiliary duct in this utility model; Figure 8 This utility model Figure 7 Enlarged view of point A in the middle. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments.

[0018] The terms "first," "second," etc. (if present) in the specification and claims of this utility model are used to distinguish similar objects, not to describe a specific order or sequence. Even if "second" is used before a technical feature for distinction, it does not necessarily imply the presence of "first." It should be understood that in this utility model, "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. It should be understood that in this utility model, "multiple" refers to two or more. "And / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, X and / or Y can represent: X alone, X and Y simultaneously, and Y alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "Containing X, Y, and Z," "Containing X, Y, and Z" means that all three X, Y, and Z are included; "Containing X, Y, or Z" means that one of X, Y, and Z is included; "Containing X, Y, and / or Z" means that any one, two, or three of X, Y, and Z are included.

[0019] The technical solution of this utility model will be described in detail below with specific embodiments. The following specific embodiments can be selected to be combined or substituted with each other according to the actual situation, and the same or similar concepts or processes may not be described again in some embodiments.

[0020] like Figure 1 As shown, this utility model provides an air preheater for increasing the temperature of the air inlet side wall, comprising multiple heat exchange plates 1 arranged sequentially at intervals, such as... Figure 2 and Figure 3 As shown, the heat exchange plate 1 includes a first thin plate 12 and a second thin plate 13. The opposite sides of the first thin plate 12 and the second thin plate 13 are welded and sealed. The middle sections of the first thin plate 12 and the second thin plate 13 are welded together by multiple welding pillars 11. The unwelded portions of the first thin plate 12 and the second thin plate 13 are spaced apart to form air channels 3 for airflow. The ends of the first thin plate 12 and the second thin plate 13 between two adjacent air channels 3 are sealed together. A flue gas channel 2 is formed between two adjacent heat exchange plates 1. Figure 4 and Figure 5As shown, the side of the first thin plate 12 and the second thin plate 13 that contacts the flue gas passage 2 is provided with a heat insulation component 4 to reduce the heat exchange between the heat exchange plate 1 and the flue gas in the flue gas passage 2. More precisely, the heat insulation component 4 is located at the air inlet end of the air passage 3. The heat insulation component 4 reduces the heat exchange efficiency between the flue gas and the air at the air inlet end of the air passage 3, ensuring that the temperature of the flue gas at the air inlet end of the air passage 3 is above the liquefaction point of ammonium bisulfate. Specifically, the first thin plate 12 and the second thin plate 13 can be corrugated plates to establish a heat transfer interface between the hot and cold media. The sealing connection between the first thin plate 12 and the second thin plate 13 can be achieved by welding or brazing to isolate the air passage 3 from the flue gas passage 2. By setting the heat insulation component 4, the necessary heat exchange function is retained while reducing the heat exchange efficiency between the flue gas and the cold air at the air inlet end of the air passage 3. This effectively prevents the temperature at the air inlet end of the air passage 3 from falling below the liquefaction temperature of ammonium bisulfate, thus avoiding the adsorption of fly ash particles in the flue gas by liquid ammonium bisulfate.

[0021] To effectively prevent excessively low flue gas temperature at the junction of the outlet area of ​​flue gas passage 2 and the inlet area of ​​air passage 3, such as... Figure 6 As shown, the length of the heat insulation component 4 in the direction of air channel 3 gradually increases along the flue gas flow direction. Specifically, the heat insulation component 4 can be implemented using a trapezoidal or wedge-shaped plate structure. As the flue gas flows in the flue gas channel 2, the closer the flue gas gets to the outlet of the flue gas channel 2, the more the length of the heat insulation component 4 increases, and the heat exchange efficiency between the flue gas and the air gradually decreases. This ensures that after the flue gas exchanges heat at the inlet, the temperature of the flue gas at the outlet of the flue gas channel 2 is less than the liquefaction temperature of ammonium bisulfate, effectively avoiding the accumulation of ash due to the liquefaction of ammonium bisulfate caused by excessively low temperature.

[0022] In another embodiment, such as Figure 5As shown, the heat insulation component 4 includes two heat insulation plates 41. The two heat insulation plates 41 are respectively attached to the heat-receiving surfaces of the first thin plate 12 and the second thin plate 13 to increase the thickness of the first thin plate 12 and the second thin plate 13, thereby reducing the heat exchange between the flue gas and the heat exchange plate 1. Specifically, one heat insulation plate 41 is attached to the heat-receiving surface of the first thin plate 12 to increase the thickness of the first thin plate 12 and reduce the heat exchange between the flue gas and the heat exchange plate 1, and the other heat insulation plate 41 is attached to the heat-receiving surface of the second thin plate 13 to increase the thickness of the second thin plate 13 and reduce the heat exchange between the flue gas and the heat exchange plate 1, thus forming heat insulation plate 41 and first thin plate 12. Alternatively, a double heat-insulating barrier of heat insulation plate 41 and second thin plate 13 can be used; the heat exchange efficiency between flue gas and air in air channel 3 can be reduced by the two heat insulation plates 41, so that the flue gas temperature in the cold air inlet area is maintained above the critical temperature of ammonium bisulfate liquefaction, significantly reducing the adhesion and deposition of viscous substances; an auxiliary flue gas channel 5 is formed between the two heat insulation plates 41 to ensure that flue gas can flow between the two heat insulation plates 41, effectively avoiding the initial heat exchange between flue gas and cold air at the tail end of the heat insulation plate 41, thereby effectively preventing the flue gas temperature from falling below the liquefaction temperature of ammonium bisulfate and causing ammonium bisulfate to adsorb fly ash particles in the flue gas.

[0023] To improve the stability of the heat insulation plate 41, the heat insulation plate 41 is integrally formed on the heat-receiving surface of the heat exchange plate 1, so that the heat insulation plate 41 and the heat-receiving surface of the heat exchange plate 1 form a continuous and seamless integral structure, ensuring structural integrity and heat conduction continuity. This eliminates the interface gaps that may be generated by traditional assembly or welding connections, avoids heat insulation failure caused by loose connections or thermal expansion differences, and can stably maintain the flue gas temperature above the liquefaction critical value of ammonium bisulfate, thereby inhibiting the deposition of viscous substances in the low-temperature region.

[0024] In another embodiment, the heat insulation plate 41 is welded to the heat exchange plate 1. The continuous weld seam formed by the welding covers the contact edge of the heat insulation plate 41 and the heat exchange plate 1, so that the two maintain a fixed relative position under the high-temperature flue gas scouring environment. The tensile strength of the welded joint can effectively resist the shear force generated by the flue gas flow, preventing the heat insulation plate 41 from shifting due to force and reducing its heat insulation protection effect on the cold air inlet. In order to improve the installation efficiency of the heat insulation plate 41, the two heat insulation plates 41 are integrally connected. When installing the heat insulation plate 41, the two heat insulation plates 41 are placed on the heat exchange plate 1, and then the heat insulation plate 41 is welded to the two heated surfaces of the heat exchange plate 1.

[0025] To ensure that the temperature of the flue gas at the inlet of air passage 3 is higher than that of ammonium bisulfate, the thickness of the heat insulation plate 41 gradually increases along the flue gas flow direction, and the width of the flue gas auxiliary passage 5 gradually decreases along the flue gas flow direction. This gradually reduces the heat exchange efficiency between the flue gas and the air in the flue gas flow direction, thereby ensuring that the temperature of the flue gas at the outlet of flue gas passage 2 is higher than that of ammonium bisulfate. This avoids the formation of liquid ammonium bisulfate, which adsorbs fly ash particles in the flue gas and forms an ash layer, causing wear, corrosion, or blockage of the heat exchanger's heating surface.

[0026] In another embodiment, the heat insulation component 4 is a heat insulation coating. The heat insulation coating is applied to the heated surfaces of the first thin plate 12 and the second thin plate 13. The heat insulation coating refers to a material layer with a low thermal conductivity, which can be achieved by using ceramic matrix composite materials or high-temperature resistant polymer coatings. Its function is to reduce the heat transfer between the heated surface and the flue gas. It can be applied to the heated surface of the heat exchanger by plasma spraying or high-temperature sintering process to form a continuous and dense heat insulation barrier, reduce the heat exchange efficiency between the flue gas and the air, and prevent the flue gas temperature from dropping too much, which would lead to the liquefaction of ammonium bisulfate.

[0027] To further reduce the temperature of the flue gas at the inlet of air passage 3 from being lower than the liquefaction temperature of ammonium bisulfate, such as... Figure 7 and Figure 8 As shown, the heat exchanger also includes a flue gas auxiliary pipe 5, and a flue gas pipe 6 is provided on the heat exchanger. The flue gas pipe 6 is connected to the flue gas passage 2, and the tail end of the flue gas auxiliary pipe 5 is connected to the air inlet end of the flue gas pipe 6. Specifically, the flue gas coming out of the boiler usually undergoes two heat exchanges with the air. The heat exchanger in this utility model is a heat exchanger for the second heat exchange. The air inlet end of the flue gas passage 2 is provided with a flue gas pipe 6. One end of the flue gas pipe 6 is connected to the flue gas passage 2, and the other end is connected to the flue gas outlet of the heat exchanger used for the first heat exchange. One end of the flue gas auxiliary pipe 5 is connected to the flue gas inlet section of the heat exchanger used for the first heat exchange, and the other end is connected to the flue gas pipe 6, thereby guiding the high-temperature flue gas with a temperature higher than that of the flue gas in the flue gas pipe 6 into the flue gas pipe 6, improving the temperature of the flue gas. Increasing the temperature of the flue gas entering flue gas passage 2, while maintaining the same heat exchange efficiency, can effectively prevent the temperature of the flue gas at the junction of the outlet area of ​​flue gas passage 2 and the inlet area of ​​air passage 3 from falling below the liquefaction temperature of ammonium bisulfate. More specifically, a guide plate 51 is provided at the outlet end of auxiliary flue gas passage 2. The function of guide plate 51 is to guide and adjust the flow direction of flue gas. Its tail end extends towards the heat exchanger used for secondary heat exchange. This design allows the flue gas discharged from the auxiliary flue gas pipe 5 to better exchange heat with the air entering air passage 3, further effectively preventing the temperature of the flue gas at the junction of the outlet area of ​​flue gas passage 2 and the inlet area of ​​air passage 3 from falling below the liquefaction temperature of ammonium bisulfate.

[0028] In this embodiment, to ensure a relatively uniform temperature in the heat exchanger along the extension direction of the air channel 3, such as... Figure 8As shown, multiple guide plates 51 are provided, and the multiple guide plates 51 are distributed at intervals; the multiple guide plates 51 work together to guide and regulate the flue gas flowing out of the flue gas auxiliary pipe 5 more precisely. Specifically, the tail ends of the multiple guide plates 51 are arranged in a fan shape to ensure that the flue gas coming out of the flue gas auxiliary pipe can mix with the lower temperature flue gas in the flue gas inlet channel over a large area, thereby improving the uniformity of the flue gas temperature entering the flue gas channel 2, reducing the temperature difference of the heat exchanger in the extension direction of the air channel 3, and improving the service life of the heat exchanger. The distance between two adjacent guide plates 51 at the outlet of the flue gas auxiliary pipe 5 gradually decreases in the direction away from the heat exchange plate 1. Specifically, the guide plates 51 are the first guide plate 511 and the second guide plate 512. The distance between the first guide plate 511 and the lower side wall of the flue gas auxiliary pipe 5 is greater than the distance between the first guide plate 511 and the second guide plate 512, which increases the amount of high temperature flue gas that exchanges heat with the air in the air inlet of the air channel 3, effectively preventing the temperature of the flue gas at the junction of the outlet area of ​​the flue gas channel 2 and the inlet area of ​​the air channel 3 from being lower than the liquefaction temperature of ammonium bisulfate.

[0029] In addition to the preferred embodiments described above, there are other embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection claimed by this utility model.

Claims

1. An air preheater for increasing the temperature of the air inlet sidewall, comprising a heat exchanger, the heat exchanger comprising a plurality of heat exchange plates arranged at intervals in sequence, each heat exchange plate comprising a first thin plate and a second thin plate, the opposite sides of the first and second thin plates being welded and sealed, the middle portions of the first and second thin plates being welded together by a plurality of welding pillars, the unwelded portions of the first and second thin plates being spaced apart to form air channels for airflow, the ends of the first and second thin plates between adjacent air channels being sealed and connected, and a flue gas channel being formed between adjacent heat exchange plates, characterized in that… The first and second thin plates are provided with heat insulation components on the side that contacts the flue gas passage to reduce the amount of heat exchange between the heat exchange plate and the flue gas in the flue gas passage. The heat insulation components are located at the air inlet end of the air passage.

2. The air preheater for increasing the air inlet sidewall temperature according to claim 1, characterized in that, The length of the heat insulation component in the air passage direction gradually increases along the flue gas flow direction.

3. The air preheater for increasing the air inlet sidewall temperature according to claim 1, characterized in that, The heat insulation component includes two heat insulation plates, which are respectively attached to the heat-receiving surfaces of the first thin plate and the second thin plate to increase the thickness of the first thin plate and the second thin plate and reduce the heat exchange between the flue gas and the heat exchange plate.

4. The air preheater for increasing the air inlet sidewall temperature according to claim 3, characterized in that, The heat insulation plate is integrally formed on the heat-receiving surface of the heat exchange plate.

5. The air preheater for increasing the air inlet sidewall temperature according to claim 3, characterized in that, The heat insulation plate is welded to the heat exchange plate.

6. The air preheater for increasing the air inlet sidewall temperature according to claim 3, characterized in that, The thickness of the heat insulation plate gradually increases along the flue gas flow direction, and the width of the flue gas auxiliary channel gradually decreases along the flue gas flow direction.

7. The air preheater for increasing the air inlet sidewall temperature according to claim 1, characterized in that, The heat insulation component is a heat insulation coating, which is applied to the heated surfaces of the first and second thin plates.

8. The air preheater for increasing the air inlet sidewall temperature according to claim 1 or 3, characterized in that, It also includes a flue gas auxiliary duct, the tail end of which is connected to the inlet end of the flue gas duct, and a guide plate is provided at the outlet end of the auxiliary flue gas passage, with the tail end of the guide plate extending towards the heat exchanger.

9. The air preheater for increasing the air inlet sidewall temperature according to claim 8, characterized in that, The guide vanes are provided in multiple pieces, which are distributed at intervals. The distance between two adjacent guide vanes at the outlet of the flue gas auxiliary pipe gradually decreases in the direction away from the heat exchange plate.

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