A heat exchanger and recovery method based on flue gas waste heat recovery of a thermal power plant

Abstract

The application discloses a heat exchanger based on flue gas waste heat recovery of a thermal power plant, and relates to the technical field of plate heat exchangers. The heat exchanger comprises a shell assembly and a plate core assembly. The shell assembly is composed of a front end plate and a rear end plate. The plate core assembly is composed of a plurality of stacked plate pieces. The application further discloses a waste heat recovery method of the heat exchanger based on flue gas waste heat recovery of the thermal power plant. The method comprises the following steps: air inlet flow stabilization, serpentine flow guide, inertial separation, liquid collection and guide, liquid discharge between plates, and tail gas discharge. The application sequentially sets a buffer flow stabilization cavity, an inertial separation cavity, a flow guide cavity, a sedimentation cavity and an exhaust cavity inside a flue gas passage formed by the plate pieces, and the cavities are jointly composed of a main flow guide rib and an auxiliary flow guide rib to form a serpentine passage. In the heat exchange process, the flue gas no longer simply flows along a traditional straight path, but is fully heat-exchanged with liquid medium after multiple turns, flow division and path extension, so that the heat exchange time and heat exchange efficiency of the flue gas side are improved.

Description

Technical Field

[0001] This invention relates to the field of plate heat exchanger technology, and in particular to a heat exchanger and recovery method based on waste heat recovery from flue gas in thermal power plants. Background Technology

[0002] Flue gas emitted from thermal power plant boilers is typically characterized by high temperature, large flow rate, and strong continuity, and still contains a significant amount of recoverable waste heat. Current waste heat utilization methods in thermal power plants often involve recovering heat from the flue gas through economizers, air preheaters, or traditional heat exchangers to improve system thermal efficiency, reduce flue gas losses, and minimize energy waste. However, with increasingly stringent energy conservation and emission reduction requirements, how to efficiently recover waste heat from flue gas within limited space while ensuring equipment operational stability and long-term reliability has become a crucial technical challenge in the field of waste heat utilization in thermal power plants.

[0003] While existing plate heat exchangers offer advantages such as high heat exchange efficiency, compact structure, and large heat transfer area per unit volume, the flow channels between plates in traditional plate heat exchangers are mostly designed for liquid-liquid heat exchange conditions. Their flow channel shapes are generally quite regular, focusing primarily on enhancing fluid turbulence and improving heat transfer efficiency. However, when directly applied to waste heat recovery scenarios in thermal power plants, the traditional flow channel structure is prone to problems such as uneven flow field distribution, ineffective separation of droplets and particles, condensate retention and accumulation, poor drainage, secondary entrainment, and tail gas entrainment. These issues can affect heat exchange efficiency and even lead to local blockage, increased corrosion, and decreased equipment operational stability.

[0004] Therefore, there is an urgent need to provide a heat exchanger and recovery method based on the recovery of waste heat from flue gas in thermal power plants, so as to improve the overall heat exchange performance and operational reliability of the equipment while retaining the high-efficiency heat exchange characteristics of plate heat exchangers. Summary of the Invention

[0005] The purpose of this invention is to provide a heat exchanger and recovery method based on waste heat recovery from flue gas in thermal power plants, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a heat exchanger based on waste heat recovery from flue gas in a thermal power plant, comprising a shell assembly and a core assembly. The shell assembly consists of a front end plate and a rear end plate. The core assembly consists of multiple layers of stacked plates, and the core assembly is located between the front end plate and the rear end plate. The multiple layers of plates are alternately and symmetrically distributed, and liquid channels and flue gas channels are alternately formed between the multiple layers of plates. The liquid channels and flue gas channels are located on both sides of the plates, respectively. The liquid channels are used for the flow of liquid media, and the flue gas channels are used for the flow of flue gas. Both ends of the plate are provided with liquid flow channels and flue gas flow channels, the liquid flow channels are connected to the liquid channel, and the flue gas flow channels are connected to the flue gas channel; The flue gas passage includes an upper buffer flow stabilizing cavity, multiple inertial separation cavities distributed vertically in the middle, and a guide cavity between adjacent inertial separation cavities, as well as a lower settling cavity and an exhaust cavity. The inertial separation cavity includes upper and lower main flow ribs and secondary flow ribs. Multiple sets of the guide cavities and inertial separation cavities form a serpentine channel. A backflow baffle is provided between the settling cavity and the exhaust cavity. A converging groove is provided inside the settling cavity. One end of each of the multiple guide cavities is connected to the converging groove.

[0007] Preferably, it also includes baffles, which are provided in multiple sets and located in multiple sets of guide cavities. The tops of the multiple sets of baffles are respectively connected to the middle of multiple secondary guide cavities. The baffles are used to extend the residence time of flue gas in the guide cavities.

[0008] Preferably, it also includes a drain outlet, which is located at the bottom of the settling chamber and penetrates the plate, the bottom end of the confluence channel is connected to the drain outlet, and the bottom end of the backflow baffle is connected to the opening of the drain outlet.

[0009] Preferably, it also includes support blocks, which are provided in multiple and fixedly disposed at one end of the drain port, and the multiple support blocks are all located in the flue gas passage; A sealing ring is fixed at the other end of the drain port and is located inside the liquid channel. The support block and the sealing ring are used to achieve liquid discharge between two adjacent flue gas channels through the drain port while maintaining the sealed isolation between the liquid channel and the flue gas channel.

[0010] Preferably, it also includes corner guide ribs, which are provided in multiple sets and located at one end of the multiple auxiliary guide ribs connected to the confluence channel. All sets of corner guide ribs are designed with an arc shape. The corner guide ribs are used to guide condensate into the confluence channel.

[0011] Preferably, it also includes buffer ribs, which are provided in multiple ways and are all located in the buffer flow stabilization cavity. The multiple buffer ribs are all provided in a zigzag structure. The buffer ribs are used to guide the flue gas to turn smoothly. The separation ribs are provided in multiple form and are all located within the inertial separation cavity. All of the separation ribs are provided as strip-shaped structures along the flue gas flow direction. The liquid collecting ribs are provided in multiple form and are all located in the flow guiding cavity. All of the liquid collecting ribs are designed as arc-shaped structures opposite to the direction of flue gas flow.

[0012] Preferably, both ends of the front end plate are provided with a liquid medium flange and a flue gas flange, the liquid medium flange being connected to a liquid channel and the flue gas flange being connected to a flue gas channel.

[0013] Preferably, guide rails are fixedly provided at both ends of the front end plate, a plurality of locking bolts are installed around the outer side wall of the front end plate, a guide groove adapted to the guide rail is provided through the top end of the rear end plate, a guide wheel is installed at the opening of the guide groove, and the guide wheel slides and fits against the upper surface of the guide rail, and a plurality of positioning grooves adapted to the locking bolts are provided around the outer side wall of the rear end plate.

[0014] Preferably, it also includes a drain tee, which is installed at the bottom end of the rear end plate on the side away from the front end plate, and one end of the drain tee is connected to the drain port.

[0015] A waste heat recovery method based on a heat exchanger for flue gas waste heat recovery in thermal power plants includes the following steps: Step 1: Inlet flow stabilization. After the flue gas enters the flue gas channel formed between the plates through the flue gas flange, it first enters the buffer flow stabilization chamber and changes its flow direction under the guidance of the buffer ribs, so that the flue gas completes the initial flow stabilization and reduces the impact before entering the downstream flow channel. The liquid medium enters the liquid flow channel formed on both sides of the plate through the liquid medium flange and flows into the liquid channel. The liquid medium and the flue gas flow separately along both sides of the plate. Step 2: Serpentine flow guidance. After the flue gas has been stabilized, it flows sequentially through the serpentine channel formed by the main flow guide, the secondary flow guide, the inertial separation cavity, and the flow guide cavity. This extends the flow path of the flue gas during multiple turns and increases the residence time in the flow guide cavity under the action of the flow guide. The heat of the flue gas is transferred to the liquid medium through the plates, achieving preliminary heat exchange. Step 3: Inertial separation. When the flue gas flows in the inertial separation chamber, the local flow field is stratified under the action of the separation ribs. This causes the droplets and particulate matter in the flue gas to deviate from the mainstream direction and gather in the lower area of ​​the inertial separation chamber. At the same time, the flue gas continues to flow downstream along the guide chamber. Step 4: Liquid collection and drainage. The condensate formed during the flow of flue gas through the guide cavity is guided by the liquid collection ribs and corner guide ribs into the collection trough, and further flows into the settling chamber. The condensate after settling is discharged through the drain port. Step 5: Interplate connection for liquid discharge and exhaust gas discharge. The condensate entering the drain port is connected between adjacent flue gas channels through the interplate connection for liquid discharge structure formed by the support block and the sealing ring, and discharged through the liquid discharge tee. After the condensate discharge is completed, the flue gas enters the exhaust chamber and is discharged through the subsequent discharge passage.

[0016] The technical effects and advantages of this invention are as follows: 1. The present invention provides a buffer flow stabilizing cavity, an inertial separation cavity, a flow guiding cavity, a settling cavity, and an exhaust cavity in sequence inside the flue gas channel formed by the plate. The main flow guide and the secondary flow guide together form a serpentine channel, so that the flue gas no longer flows simply along the traditional straight path during the heat exchange process, but undergoes multiple turns, diversions, and extensions before fully exchanging heat with the liquid medium, thereby improving the heat exchange time and heat exchange efficiency on the flue gas side. 2. This invention, by setting separation ribs in the inertial separation chamber, liquid collection ribs in the guide chamber, and corner guide ribs at the connection end between the secondary guide ribs and the collection channel, allows droplets, particulate matter, and condensate in the flue gas to gradually complete inertial separation, low-level aggregation, and directional flow during the serpentine flow process. Then, they are discharged in an orderly manner through the settling chamber, the drain port, and the drain tee. The anti-reverse flow ribs separate the settling chamber from the exhaust chamber, which can effectively prevent the settled condensate and particulate matter from being re-entrained by the exhaust airflow, thereby improving the stability of condensate discharge and reducing the risk of liquid retention, secondary entrainment, and local blockage. 3. This invention, by setting support blocks and sealing rings at both ends of the drain port, achieves inter-plate communication and drainage between adjacent flue gas channels while ensuring the sealed isolation between the liquid channel and the flue gas channel. This allows the condensate collected in multiple flue gas channels to be discharged in an orderly manner, avoiding localized liquid accumulation. The front plate, rear plate, guide rail, guide groove, guide wheel, locking bolt, and positioning groove together form a structural system that facilitates installation, disassembly, and positioning locking. This is beneficial for the assembly, maintenance, and repair of the core plate assembly, and improves the overall engineering applicability of the equipment. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0018] Figure 2 This is a schematic diagram showing the overall structure of the present invention broken down.

[0019] Figure 3 This is a schematic diagram of the plate structure of the present invention. Figure 1 .

[0020] Figure 4 This is a schematic diagram of the plate structure of the present invention. Figure 2 .

[0021] Figure 5 For the present invention Figure 4 Enlarged schematic diagram of the structure at point A in the middle.

[0022] Figure 6 This is a schematic diagram of the plate structure of the present invention. Figure 3 .

[0023] Figure 7 For the present invention Figure 6 Enlarged schematic diagram of the structure at point B.

[0024] Figure 8 This is a schematic diagram of the back-end board structure of the present invention.

[0025] Figure 9 This is a schematic diagram of the front-end board structure of the present invention.

[0026] In the diagram: 1. Front end plate; 11. Liquid medium flange; 12. Flue gas flange; 13. Guide rail; 14. Locking bolt; 2. Plate; 21. Liquid flow channel; 22. Flue gas flow channel; 221. Main flow guide rib; 2211. Buffer rib; 222. Secondary flow guide rib; 2221. Separation rib; 2223. Liquid collection rib; 224. Backflow barrier rib; 225. Baffle rib; 226. Merging groove; 2261. Corner flow guide rib; 227. Drain port; 2271. Support block; 2272. Sealing ring; 3. Rear end plate; 31. Guide groove; 311. Guide wheel; 32. Positioning groove; 33. Drain tee. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] like Figures 1 to 9 As shown, the heat exchanger based on waste heat recovery from flue gas in thermal power plants provided by the present invention is essentially based on the traditional plate heat exchanger where plates are stacked to form liquid channels and flue gas channels. The internal flow field of the flue gas channel is partitioned to improve the adaptability and operational stability of the plate heat exchanger in the scenario of waste heat recovery from flue gas in thermal power plants.

[0029] In terms of specific structural installation, the structural body can be constructed according to the inventive concept of this embodiment. In this embodiment, no special limitations are imposed.

[0030] In this embodiment, a heat exchanger based on waste heat recovery from flue gas in a thermal power plant includes a shell assembly and a core assembly. The shell assembly consists of a front plate 1 and a rear plate 3. The core assembly is composed of multiple layers of plates 2 stacked together, and is located between the front plate 1 and the rear plate 3. The multiple layers of plates 2 are symmetrically distributed alternately, and liquid channels and flue gas channels are alternately formed between the multiple layers of plates 2. The liquid channels and flue gas channels are located on both sides of the plates 2, respectively. The liquid channels are used for the flow of liquid media, and the flue gas channels are used for the flow of flue gas. Both ends of the plates 2 are provided with liquid flow channels 21 and flue gas flow channels 22. The liquid flow channels 21 are connected to the liquid channels, and the flue gas flow channels 22 are connected to the flue gas channels. The plates 2 are made of stainless steel plates, heat-resistant and corrosion-resistant alloy plates, or composite materials. Metal plates are processed by stamping, hydroforming, die stretching, or roll forming. In mass production, a special mold can be used to stamp and form the plates in one go, so that liquid flow channels, flue gas flow channels, and various ribs, grooves, and cavity contours are formed simultaneously on the surface of the plates. For local deep settling cavities, drainage outlet transition areas, or complex flow guiding areas, a combination of step-by-step stamping and subsequent shaping and leveling can be used to reduce the risk of cracking and springback. The liquid flow channels are formed by herringbone, corrugated, oblique rib, or cross-turbulence convex and concave structures formed by stamping the plates. The forming method is mainly stamping and die forming. The cross section of the liquid flow channels can maintain the enhanced heat transfer texture common in traditional plate heat exchangers to inherit the existing mature high heat transfer efficiency structure on the liquid side.

[0031] The flue gas passage is provided with a buffer flow stabilization chamber, an inertial separation chamber, a settling chamber and an exhaust chamber from top to bottom. The inertial separation chamber is provided in multiple vertically distributed chambers, and a guide chamber is provided between each of the multiple inertial separation chambers. The inertial separation chamber includes a main flow guide rib 221 and a secondary flow guide rib 222 distributed vertically. The multiple sets of guide chambers and inertial separation chambers form a serpentine passage. After the flue gas enters the flue gas passage, it turns multiple times in the path defined by the main flow guide rib 221 and the secondary flow guide rib 222. The serpentine flow guide extends the flow path and increases the residence time of the flue gas on the flue gas side of the plate 2, thereby enhancing the heat exchange effect between the flue gas and the liquid medium in the liquid passage.

[0032] The buffer flow stabilization cavity is equipped with multiple buffer ribs 2211, all of which are designed as a broken line structure. After the flue gas enters the flue gas channel through the flue gas flange 12, it first enters the buffer flow stabilization cavity and gradually disperses and changes direction under the action of multiple buffer ribs 2211 to reduce the initial impact velocity of the flue gas, prevent the flue gas from directly impacting the downstream separation structure, and improve the flow field stability of the flue gas before entering the serpentine channel.

[0033] The inertial separation chamber is equipped with multiple separation ribs 2221, which are arranged along the flue gas flow direction. When the flue gas passes through the inertial separation chamber, the droplets and particulate matter in the flue gas deviate from the mainstream under the action of inertia, and migrate to the lower part of the chamber under the local flow field regulation effect formed by the separation ribs 2221, which is conducive to the separation of droplets and particulate matter from the main flue gas flow.

[0034] The flow guiding cavity is equipped with multiple sets of baffles 225, the tops of which are connected to the middle of multiple secondary flow guiding ribs 222. The baffles 225 can further extend the flow path and residence time of the flue gas in the flow guiding cavity, allowing the flue gas to form a more complete heat exchange process in the flow guiding cavity and increasing the chance of condensation of the flue gas during the temperature drop process.

[0035] The guide cavity is also equipped with multiple liquid collecting ribs 2223, all of which are arc-shaped structures opposite to the flue gas flow direction. When the flue gas flows and condenses in the guide cavity, the condensate flows along a predetermined path to the end of the guide cavity under the combined action of gravity and the liquid collecting ribs 2223. To further improve the condensate introduction efficiency, corner guide ribs 2261 are respectively provided at the end where multiple secondary guide ribs 222 are connected to the confluence channel 226. All sets of corner guide ribs 2261 are arc-shaped structures, which can smoothly introduce the condensate flowing down from the end of the guide cavity into the confluence channel 226, reducing the retention of condensate in the corner area.

[0036] The settling chamber is located in the lower part of the serpentine flow path. Inside it is a confluence channel 226. One end of each of the multiple flow channels is connected to the confluence channel 226. The condensate and entrained particulate matter that flow into the confluence channel 226 further flow into the settling chamber and undergo further settling and separation. A backflow baffle 224 is provided between the settling chamber and the exhaust chamber. The backflow baffle 224 is used to spatially separate the settling chamber and the exhaust chamber, so that a relatively low-speed liquid settling area is formed in the settling chamber, while the exhaust chamber forms a tail gas discharge area, thereby preventing the condensate and particulate matter in the settling chamber from being re-entrained by the flue gas flowing into the exhaust chamber.

[0037] The bottom of the settling chamber is provided with a drain port 227 that penetrates the plate 2. The bottom end of the confluence channel 226 is connected to the drain port 227. The bottom end of the backflow baffle 224 is connected to the slot of the drain port 227. The condensate settling at the bottom of the settling chamber can be discharged outward through the drain port 227. One end of the drain port 227 is provided with multiple support blocks 2271, and the other end is provided with a sealing ring 2272. The support blocks 2271 are located in the flue gas channel, and the sealing ring 2272 is located in the liquid channel. The two together ensure the structural stability and sealing isolation effect of the drain port 227 area, and at the same time realize the connection and drainage between two adjacent flue gas channels.

[0038] A drain tee 33 is installed at the bottom of the rear end plate 3 on the side away from the front end plate 1. One end of the drain tee 33 is connected to the drain port 227. The discharged condensate can be discharged through the drain tee 33 for subsequent collection, discharge or treatment. A valve can be installed at the discharge end of the drain tee 33. Periodic drainage can be achieved by opening the valve periodically. During normal operation of the device, the valve is normally closed to prevent flue gas from leaking through the drain tee 33.

[0039] Both ends of the front end plate 1 are provided with a liquid medium flange 11 and a flue gas flange 12. The liquid medium flange 11 is connected to the liquid channel, and the flue gas flange 12 is connected to the flue gas channel, which are used to introduce and export liquid medium and flue gas respectively.

[0040] The front end plate 1 has guide rails 13 fixed at both ends. Multiple locking bolts 14 are installed around the outer side wall of the front end plate 1. The top end of the rear end plate 3 has a guide groove 31 that is adapted to the guide rail 13. A guide wheel 311 is installed at the opening of the guide groove 31 and slides against the upper surface of the guide rail 13. Multiple positioning grooves 32 that are adapted to the locking bolts 14 are installed around the outer side wall of the rear end plate 3. Through the cooperation of the guide rail 13, guide groove 31, guide wheel 311, locking bolts 14 and positioning grooves 32, the rear end plate 3 can be guided, installed, aligned and locked and disassembled for maintenance relative to the front end plate 1.

[0041] A waste heat recovery method based on a heat exchanger for flue gas waste heat recovery in thermal power plants specifically includes the following steps: Step 1: Inlet flow stabilization. After the flue gas enters the flue gas channel formed between the plates 2 through the flue gas flange 12, it first enters the buffer flow stabilization chamber and changes its flow direction under the guidance of the buffer rib 2211, so that the flue gas completes the initial flow stabilization and reduces the impact before entering the downstream flow channel. At the same time, the liquid medium enters the liquid flow channel 21 formed on both sides of the plate 2 through the liquid medium flange 11 and flows into the liquid channel. The liquid medium and the flue gas flow separately along both sides of the plate 2.

[0042] Step 2: Serpentine flow guidance. After the flue gas has been stabilized, it flows sequentially through the serpentine channel formed by the main flow guide rib 221, the secondary flow guide rib 222, the inertial separation cavity, and the flow guide cavity. This extends the flow path of the flue gas during multiple turns and increases the residence time in the flow guide cavity under the action of the baffle rib 225. The heat of the flue gas is transferred to the liquid medium through the plate 2, achieving preliminary heat exchange.

[0043] Step 3: Inertial separation. When the flue gas flows in the inertial separation chamber, it forms a local flow field stratification under the action of the separation rib 2221, causing the droplets and particulate matter in the flue gas to deviate from the mainstream direction and gather in the lower area of ​​the inertial separation chamber. At the same time, the flue gas continues to flow downstream along the guide chamber.

[0044] Step 4: Liquid collection and drainage. The condensate formed during the flow of flue gas through the guide cavity is guided by the liquid collection rib 2223 and the corner guide rib 2261 into the collection groove 226, and further flows into the settling chamber. The settled condensate is discharged through the drain port 227.

[0045] Step 5: Interplate connection for liquid discharge and exhaust gas discharge. The condensate entering the drain port 227 is connected between adjacent flue gas channels through the interplate connection for liquid discharge structure formed by the support block 2271 and the sealing ring 2272, and discharged through the drain tee 33. After the condensate discharge is completed, the flue gas enters the exhaust chamber and is discharged through the subsequent discharge passage.

[0046] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A heat exchanger based on waste heat recovery from flue gas in thermal power plants, comprising a shell assembly and a core plate assembly, characterized in that: The shell assembly consists of a front plate (1) and a rear plate (3). The core assembly consists of multiple layers of plates (2) stacked together. The core assembly is located between the front plate (1) and the rear plate (3). The multiple layers of plates (2) are symmetrically distributed and liquid channels and flue gas channels are alternately formed between the multiple layers of plates (2). The liquid channels and flue gas channels are located on both sides of the plates (2). The liquid channels are used for the flow of liquid media, and the flue gas channels are used for the flow of flue gas. Both ends of the plate (2) are provided with a liquid flow channel (21) and a flue gas flow channel (22). The liquid flow channel (21) is connected to the liquid channel, and the flue gas flow channel (22) is connected to the flue gas channel. The flue gas passage includes an upper buffer flow stabilizing cavity, multiple inertial separation cavities located in the middle and distributed vertically, a guide cavity disposed between adjacent inertial separation cavities, and a settling cavity and an exhaust cavity located at the bottom. The inertial separation cavity includes a main flow rib (221) and a secondary flow rib (222) distributed vertically. Multiple sets of the guide cavities and the inertial separation cavities form a serpentine channel. A backflow baffle rib (224) is provided between the settling cavity and the exhaust cavity. A converging groove (226) is provided inside the settling cavity. One end of each of the multiple guide cavities is connected to the converging groove (226).

2. A heat exchanger based on waste heat recovery from flue gas in a thermal power plant according to claim 1, characterized in that, Also includes: The baffle (225) is provided in multiple sets and is located in multiple sets of flow guide cavities. The top of the multiple sets of baffle (225) is connected to the middle of multiple secondary flow guide ribs (222). The baffle (225) is used to extend the residence time of flue gas in the flow guide cavity.

3. A heat exchanger based on waste heat recovery from flue gas in a thermal power plant according to claim 1, characterized in that, Also includes: The drain port (227) is located at the bottom of the settling chamber and penetrates the plate (2). The bottom end of the confluence channel (226) is connected to the drain port (227), and the bottom end of the backflow baffle (224) is connected to the opening of the drain port (227).

4. A heat exchanger based on waste heat recovery from flue gas in a thermal power plant according to claim 3, characterized in that, Also includes: Support blocks (2271) are provided in multiple and are fixedly installed at one end of the drain port (227), and the multiple support blocks (2271) are all located in the flue gas passage; A sealing ring (2272) is fixedly disposed at the other end of the drain port (227), and the sealing ring (2272) is located in the liquid channel. The support block (2271) and the sealing ring (2272) are used to realize the connection and drainage between two adjacent flue gas channels through the drain port while maintaining the sealed isolation between the liquid channel and the flue gas channel.

5. A heat exchanger based on waste heat recovery from flue gas in a thermal power plant according to claim 1, characterized in that, Also includes: The corner guide rib (2261) is provided in multiple sets and is located at one end of the connection between multiple auxiliary guide ribs (222) and the confluence channel (226). All sets of the corner guide ribs (2261) are designed as arc-shaped structures. The corner guide ribs (2261) are used to guide condensate into the confluence channel (226).

6. A heat exchanger based on waste heat recovery from flue gas in a thermal power plant according to claim 1, characterized in that, Also includes: Buffer ribs (2211) are provided in multiple form and are all located in the buffer flow stabilization cavity. The multiple buffer ribs (2211) are all provided in a zigzag structure. The buffer ribs (2211) are used to guide the flue gas to turn smoothly. Separation ribs (2221) are provided in multiple form and are all located in the inertial separation cavity. All separation ribs (2221) are provided as strip structures along the flue gas flow direction. The liquid collecting ribs (2223) are provided in multiple form and are all located in the flow guiding cavity. The multiple liquid collecting ribs (2223) are all designed as arc-shaped structures opposite to the direction of flue gas flow.

7. A heat exchanger based on waste heat recovery from flue gas in a thermal power plant according to claim 1, characterized in that: Both ends of the front end plate (1) are provided with a liquid medium flange (11) and a flue gas flange (12). The liquid medium flange (11) is connected to the liquid channel, and the flue gas flange (12) is connected to the flue gas channel.

8. A heat exchanger based on waste heat recovery from flue gas in a thermal power plant according to claim 1, characterized in that: Both ends of the front end plate (1) are fixed with guide rails (13). Multiple locking bolts (14) are installed around the outer side wall of the front end plate (1). The top end of the rear end plate (3) is provided with a guide groove (31) that is compatible with the guide rail (13). A guide wheel (311) is installed at the opening of the guide groove (31), and the guide wheel (311) slides and fits against the upper surface of the guide rail (13). Multiple positioning grooves (32) that are compatible with the locking bolts (14) are provided around the outer side wall of the rear end plate (3).

9. A heat exchanger based on waste heat recovery from flue gas in a thermal power plant according to claim 3, characterized in that, Also includes: A drain tee (33) is installed on the bottom side of the rear end plate (3) away from the front end plate (1), and one end of the drain tee (33) is connected to the drain port (227).

10. A waste heat recovery method based on a heat exchanger for recovering waste heat from flue gas in a thermal power plant, applied to the heat exchanger for recovering waste heat from flue gas in a thermal power plant as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Inlet flow stabilization. After the flue gas enters the flue gas channel formed between the plates (2) through the flue gas flange (12), it first enters the buffer flow stabilization chamber and changes its flow direction under the guidance of the buffer rib (2211), so that the flue gas completes the initial flow stabilization and reduces the impact before entering the downstream flow channel. The liquid medium enters the liquid flow channel (21) formed on both sides of the plate (2) through the liquid medium flange (11) and flows into the liquid channel. The liquid medium and the flue gas flow separately along both sides of the plate (2) in isolation. Step 2: Serpentine flow guidance. After the flue gas has been stabilized, it flows through the serpentine channel formed by the main flow guide (221), the secondary flow guide (222), the inertial separation cavity and the flow guide cavity. This extends the flow path of the flue gas during multiple turns and increases the residence time in the flow guide cavity under the action of the baffle (225). The heat of the flue gas is transferred to the liquid medium through the plate (2), achieving preliminary heat exchange. Step 3: Inertial separation. When the flue gas flows in the inertial separation chamber, it forms a local flow field stratification under the action of the separation rib (2221), causing the droplets and particulate matter in the flue gas to deviate from the mainstream direction and gather in the lower area of ​​the inertial separation chamber. At the same time, the flue gas continues to flow downstream along the guide chamber. Step 4: Liquid collection and drainage. The condensate formed during the flow of flue gas through the guide cavity is guided by the liquid collection rib (2223) and the corner guide rib (2261) to flow into the collection trough (226) and further flow into the settling chamber. The condensate after settling is discharged through the drain port (227). Step 5: Interplate connection for liquid discharge and exhaust gas discharge. The condensate entering the drain port (227) is connected between adjacent flue gas channels through the interplate connection for liquid discharge structure formed by the support block (2271) and the sealing ring (2272), and discharged through the drain tee (33). After the condensate discharge is completed, the flue gas enters the exhaust chamber and is discharged through the subsequent discharge passage.

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