Self-cleaning waste heat recovery system

Abstract

This invention discloses a self-cleaning waste heat recovery system, relating to the field of energy-saving equipment technology. The self-cleaning waste heat recovery system includes a gas-to-gas heat exchanger, a spray mechanism, a backflushing cleaning mechanism, and an oil separator, and can be directly installed on top of the drying equipment. The gas-to-gas heat exchanger contains a rotatable plate heat exchanger, which is arranged at a 45° angle during normal operation. A duct sealing strip separates the fresh air and exhaust gas channels to achieve waste heat recovery. When the heat exchange efficiency decreases, the heat exchanger rotates at low speed, the spray mechanism sprays hot water to clean the internal oil and fiber residue, and the backflushing mechanism automatically cleans the inlet filter to prevent clogging. The system is equipped with an oil separator to achieve wastewater removal, oil-water separation, and hot water recycling. The entire process is automated, requiring no disassembly for cleaning, and is easy to install and maintain, ensuring long-term, efficient, and stable operation of the drying equipment.

Description

Technical Field

[0001] This invention belongs to the field of energy-saving equipment technology, and in particular relates to a self-cleaning waste heat recovery system. Background Technology

[0002] In industrial production sectors such as dried fruit processing, textile printing and dyeing fabric drying or setting, and agricultural product drying, drying equipment generally relies on high-temperature hot air to dehydrate or set materials. This equipment continuously emits large amounts of high-temperature waste gas during operation. Directly releasing this waste gas into the atmosphere not only results in significant energy waste and increased energy costs for businesses, but also exacerbates environmental heat pollution, contradicting the current trend of energy conservation and emission reduction in industrial development. Therefore, recovering and utilizing the waste heat from drying waste gas has become a key technological direction for related industries to reduce energy consumption and improve economic efficiency.

[0003] In existing technologies, the most common waste heat recovery method is to construct an air-to-air heat exchange system using plate heat exchangers. This system transfers the waste heat from the exhaust gas to ambient temperature fresh air. The preheated fresh air is then reintroduced into the drying equipment as a heat source for drying. The exhaust gas, after heat exchange, is discharged through exhaust pipes and exhaust fans, thus achieving heat energy recycling. However, the exhaust gas generated during the drying process has a complex composition. In addition to water vapor, it also carries a large amount of fine fibers shed from materials (such as fiber fragments from dyed fabrics and plant fibers from agricultural products), dust, and impurities such as oil volatilized during the drying process. When these impurities enter the plate heat exchanger with the high-temperature exhaust gas, the narrow heat exchange channels and reduced airflow velocity inside the heat exchanger, along with the temperature drop of the exhaust gas during the heat exchange process causing oil condensation, cause the fine fibers, dust, and condensed oil to adhere to each other, firmly attaching to the surface of the heat exchange plates and the inner walls of the channels. Over time, these deposits accumulate and thicken, increasing airflow resistance, reducing heat exchange efficiency, and in severe cases, directly blocking heat exchange channels, causing the heat exchange system to malfunction and forcing the drying equipment to shut down for maintenance. To address this issue, some technological improvements have been made in related fields. For example, a rotating inlet filter is used to separate fibrous impurities from the exhaust gas, and an air knife is used to automatically clean the inlet filter, achieving continuous filtration. Furthermore, the cleaned fibrous impurities can be collected separately through a collection port to prevent them from returning to the drying oven.

[0004] However, the aforementioned existing technology still has significant drawbacks: Since the air intake filter can only intercept larger-diameter fibrous impurities, it struggles to effectively filter smaller-diameter fine fibers, dust, and gaseous oil. These small impurities can still enter the plate heat exchanger and adhere to the heat exchange channels, leading to a continuous decline in heat exchange efficiency over time. Furthermore, the device does not provide an effective cleaning solution for the impurities already attached to the heat exchanger. When the heat exchange efficiency drops to a certain level, users still need to disassemble and clean the heat exchanger. Disassembly and cleaning not only consume significant manpower, resources, and time, increasing the maintenance burden on product manufacturers, but also cause prolonged downtime of the drying equipment, severely impacting normal production operations and resulting in economic losses. Summary of the Invention

[0005] This invention addresses the technical problem of existing waste heat recovery equipment's plate heat exchangers experiencing reduced heat mixing efficiency due to oil and dust buildup, requiring regular disassembly and maintenance, resulting in high maintenance costs and production delays. It proposes a self-cleaning waste heat recovery system that eliminates the need for disassembly, allowing the heat exchanger assembly to rotate internally and be cleaned via a spray system.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A self-cleaning waste heat recovery system includes one or more sets of gas-to-gas heat exchangers installed on a drying equipment. The gas-to-gas heat exchangers include a heat exchanger assembly, a housing, a spray mechanism, and a backflushing cleaning mechanism. The heat exchanger assembly includes a square plate heat exchanger, with circular rotating sealing plates connected to both ends of the plate heat exchanger, and a rotating shaft installed at the center of the rotating sealing plate; air duct sealing strips are installed at the four edges of the vertical rotating sealing plate of the plate heat exchanger. The housing is equipped with a fresh air inlet, a fresh air outlet, an exhaust gas inlet, and an exhaust gas outlet. A wastewater outlet is located at the bottom of the housing, and the exhaust gas outlet is connected to an exhaust fan via a pipeline. A filter screen is installed at the lower end of the exhaust gas inlet, and a back-flushing cleaning mechanism is installed inside the filter screen. The front and rear walls of the housing are equipped with heat exchanger mounting holes that match the rotating sealing plate and bearing seats for supporting the rotating shaft. A rotating traction motor for driving the rotating shaft is installed on the side of one of the bearing seats. When the heat exchanger assembly is installed in the housing at a 45-degree angle, the air duct sealing strip contacts the outer wall of the housing to form a fresh air ventilation duct and an exhaust gas ventilation duct. The spraying mechanism includes a spray pipe installed on the upper part of the box, which is connected to a water source via a water pipe, and has multiple nozzles on it.

[0007] Preferably, the backflushing cleaning mechanism includes an exhaust gas backflushing pipe, an exhaust gas backflushing motor, and a rotary joint. The lower end of the exhaust gas backflushing pipe is connected to an air nozzle, and the upper end of the exhaust gas backflushing pipe is connected to a backflushing pipe connecting bushing. A bearing assembly is installed above the backflushing pipe connecting bushing and connected to the inner ring of the bearing assembly. A driven gear is also fitted on the backflushing pipe connecting bushing. The exhaust gas backflushing motor and the rotary joint are fixed on the exhaust gas inlet. The output shaft of the exhaust gas backflushing motor is connected to a driving gear meshing with the driven gear. The rotary joint is connected to the outer ring of the bearing assembly and is connected to an air source via an air pipe.

[0008] Preferably, the jet nozzles are configured in multiple groups, each jetting air at different angles along the vertical direction.

[0009] Preferably, a sealing strip base plate is welded to the circumferential surface of the rotary sealing plate, and a sealing strip is installed on the sealing strip base plate and pressed tightly by the sealing strip pressure plate.

[0010] Preferably, a spray pipe mounting plate is installed on the inner side of the rear side wall of the box, the spray pipe mounting plate is provided with a groove, and a pipe cap that can be inserted into the groove is provided at one end of the spray pipe; a spray pipe fixing plate is welded to the other end of the spray pipe, and a spray pipe mounting hole is provided on the front side wall of the box. The pipe cap of the spray pipe is inserted into the box through the spray pipe mounting hole and embedded in the groove, and the spray pipe fixing plate is fixed to the box by bolts.

[0011] Preferably, the rotating shaft is welded to a load-bearing connecting plate, which is then bolted to the rotating sealing plate.

[0012] Preferably, the inner wall of the housing is provided with a sealing surface that contacts the air duct sealing strip.

[0013] Preferably, temperature sensors are installed at the fresh air inlet, fresh air outlet, exhaust gas inlet, and exhaust gas outlet.

[0014] Preferably, the system also includes an oil separator, which includes a water tank divided into a primary water tank and a secondary water tank by a partition in the middle of the water tank. A connecting hole is provided at the bottom of the partition. A steam heating pipe, an overflow pipe, and a water inlet are installed on the side wall of the primary water tank. A linear vibrating screen is also installed on the primary water tank. The wastewater outlet is connected to the top of the linear vibrating screen via a wastewater pipe, and the linear vibrating screen removes impurities from the wastewater. A water supply pipe and a water pump connected to the spray pipe are provided on the side wall of the secondary water tank.

[0015] Preferably, the primary water tank is also equipped with an oil removal machine, which includes an active roller located above the water surface and a driven roller located below the water surface. A belt connects the active roller and the driven roller. An oil scraper is provided on one side of the active roller to scrape the belt, and an oil receiving groove is provided at the bottom of the oil scraper.

[0016] Compared with the prior art, the advantages and positive effects of the present invention are as follows: 1. The self-cleaning waste heat recovery system of this invention achieves efficient heat exchange between high-temperature exhaust gas and low-temperature fresh air through a plate heat exchanger, recovering and utilizing 30%-50% of the waste heat in the exhaust gas. The preheated fresh air is then reintroduced into the drying equipment, significantly reducing the heat source consumption of the drying equipment and saving energy costs.

[0017] 2. In the gas-to-gas heat exchanger, the heat exchanger assembly is designed as a rotating structure. When the heat exchange efficiency decreases, a spray cleaning process is performed during production breaks. At this time, the rotating traction motor drives the plate heat exchanger to rotate at low speed, and the spray pipes spray high-temperature hot water to wash away oil stains and fine fibers from the inner wall of the heat exchange channel from all angles. The cleaning wastewater flows out by gravity, achieving a thorough cleaning effect without the need for manual disassembly and cleaning. Furthermore, temperature sensors monitor the inlet and outlet temperatures of fresh air and exhaust gas in real time, automatically determining the heat exchange efficiency and triggering the cleaning program without manual intervention.

[0018] 3. The filter screen at the exhaust gas inlet is automatically cleaned at regular intervals by a 360° rotating jet backflush pipe. The fine fibers and dust on the filter screen are removed by spraying compressed air, preventing large particles of impurities from entering the heat exchanger channel and reducing the risk of blockage from the source. Moreover, the cleaning process does not affect the normal operation of the drying equipment and does not require shutdown.

[0019] 4. The system is equipped with an oil separator to achieve graded treatment of cleaning wastewater. After solid impurities are removed by a linear vibrating screen and oil is separated by a floating oil remover, clean water enters the secondary water tank for circulation and supply to the spraying mechanism, significantly saving water resources. The primary water tank heats the circulating water through steam heating pipes, and the hot water spray can efficiently dissolve oil and improve the cleaning effect; at the same time, water is automatically replenished and the temperature is controlled by liquid level and temperature sensors, requiring no manual operation and reducing maintenance costs.

[0020] 5. The self-cleaning waste heat recovery system of the present invention has a compact structure and can be directly installed on the top of existing drying equipment. The exhaust gas inlet and fresh air outlet of the gas-to-gas heat exchange device can be directly connected to the original air outlet and air inlet of the drying equipment. The exhaust gas outlet is connected to the original main exhaust pipe through the branch exhaust pipe. There is no need to modify the main structure of the drying equipment. The installation cost is low, the cycle is short, and it is convenient to upgrade and modify existing equipment. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the self-cleaning waste heat recovery system of the present invention; Figure 2 This is a schematic diagram of the gas-to-gas heat exchange device of the self-cleaning waste heat recovery system of the present invention. Figure 3 This is a schematic diagram of the plate heat exchanger structure of the self-cleaning waste heat recovery system of the present invention. Figure 4This is a schematic diagram of the duct sealing strip fixing structure of the self-cleaning waste heat recovery system of the present invention; Figure 5 This is a schematic diagram of the internal structure of the self-cleaning waste heat recovery system of the present invention. Figure 6 This is a schematic diagram of the box structure of the self-cleaning waste heat recovery system of the present invention; Figure 7 This is a schematic diagram of the spray mechanism structure of the self-cleaning waste heat recovery system of the present invention; Figure 8 This is a schematic diagram of the fresh air inlet structure of the self-cleaning waste heat recovery system of the present invention; Figure 9 This is a schematic diagram of the waste gas backflushing device of the self-cleaning waste heat recovery system of the present invention. Figure 10 This is a schematic diagram of the drive device structure of the exhaust gas backflushing device of the self-cleaning waste heat recovery system of the present invention. Figure 11 This is a schematic diagram of the oil separator structure of the self-cleaning waste heat recovery system of the present invention; Figure 12 This is a schematic diagram of the working state of the self-cleaning waste heat recovery system of the present invention; Figure 13 This is a schematic diagram of the clean state of the self-cleaning waste heat recovery system of the present invention; In the above figures: 10. Drying equipment; 101. Main exhaust pipe; 102. Exhaust fan; 20. Heat exchanger assembly; 201. Plate heat exchanger; 202. Rotary sealing plate; 203. Load-bearing connecting plate; 204. Rotating shaft; 205. Duct sealing strip; 206. Angle steel; 207. Sealing strip connecting base plate; 208. Sealing strip connecting top plate; 209. Sealing strip base plate; 210. Sealing strip; 211. Sealing strip pressure plate; 30. Housing; 301. Fresh air outlet; 302. Exhaust gas inlet; 303. Filter screen; 304. Exhaust gas outlet; 305. Outlet branch pipe; 306. Fresh air inlet; 3061. Waterproof fog louver; 307. Fresh air supply fan; 308. Wastewater outlet; 309. Heat exchanger mounting hole; 310. Rotary traction motor; 311. Sealing surface; 312. Crossbeam; 313. Water baffle; 314. Bottom inclined plate; 315. Temperature sensor; 40. Spraying mechanism; 401. Spraying pipe; 402. Spraying pipe mounting plate; 403. Spraying pipe fixing plate; 404. Nozzle; 405. Groove; 50. Backflush cleaning mechanism; 501. Exhaust gas backflush motor; 502. Drive gear; 503. Driven gear; 504. Bearing assembly; 505. Rotary joint; 506. Exhaust gas backflush pipe; 507. Backflush connector; 508. Exhaust gas backflush pipe connecting bushing; 509. Air jet nozzle; 60. Oil separator; 601. Water tank; 6011. Primary water tank; 6012. Secondary water tank; 602. Baffle plate; 6021. Connecting hole; 603. Steam heating pipe; 604. Overflow pipe; 605. Water inlet; 607. Water supply temperature sensor; 608. Water supply pipe; 609. Water pump; 70. Linear vibrating screen; 701. Screen mesh; 702. Drive unit; 703. Spring; 80. Oil skimming machine; 801. Oil receiving tank; 802. Driven roller; 803. Belt. Detailed Implementation

[0022] Example: Figure 1-13 As shown, a self-cleaning waste heat recovery system includes one or more sets of gas-to-gas heat exchangers installed on a drying device 10. The top of the drying device 10 is equipped with a main exhaust pipe 101 and an exhaust fan 102. Low-temperature fresh air and exhaust gas discharged from the drying device 10 both enter the gas-to-gas heat exchangers for heat exchange. The low-temperature fresh air absorbs heat from the high-temperature exhaust gas through heat exchange and becomes high-temperature fresh air, which then enters the drying device 10. The low-temperature exhaust gas after heat exchange is discharged into the main exhaust pipe through a branch exhaust pipe and finally discharged into the next process for treatment by the exhaust fan 102.

[0023] After a long period of operation, the heat exchange efficiency of the gas-to-gas heat exchanger will decrease due to the accumulation of oil stains on the inner wall of the heat exchange channel. In this embodiment, the gas-to-gas heat exchanger includes a heat exchanger assembly 20, a housing 30, a spray mechanism 40, a backflushing cleaning mechanism 50, and a controller. The spray mechanism 40 can automatically clean the heat exchanger assembly 20, and the backflushing cleaning mechanism 50 can periodically clean the air intake filter, achieving automatic and efficient maintenance.

[0024] like Figure 3 , Figure 4 As shown, the heat exchanger assembly 20 includes a plate heat exchanger 201 with a square cross-section. Both ends of the plate heat exchanger 201 are connected to circular rotating sealing plates 202. A load-bearing connecting plate 203 is bolted to the center of the rotating sealing plate 202, and a rotating shaft 204 is welded to the center of the load-bearing connecting plate 203. Air duct sealing strips 205 are installed on the four edges of the plate heat exchanger 201 perpendicular to the surface of the rotating sealing plate 202. Specifically, angle steel 206 is welded to the ends of the edges of the plate heat exchanger 201, and a sealing strip connecting base plate 207 is welded to the angle steel 206. The air duct sealing strip 205 is installed on the sealing strip connecting base plate 207 and fixed through a sealing strip connecting top plate 208.

[0025] like Figure 2 , Figure 5 , Figure 6 As shown, a fresh air outlet 301 is provided on the lower left side wall of the housing 30. This fresh air outlet 301 is a rectangular metal box, and the opening of the metal box 30 is connected to the air inlet of the drying equipment 10, which can deliver hot air into the drying equipment 10. An exhaust gas inlet 302 is provided on the lower right side wall of the housing 30. This exhaust gas inlet 302 is also a rectangular metal box, and the opening of the metal box 30 is connected to the air outlet of the drying equipment 10, which discharges hot and humid air from the drying equipment 10. A filter screen 303 is provided below the air outlet of the drying equipment 10. The filter screen 303 can prevent excessive fine fibers, dust, etc. from entering the plate heat exchanger 201 and blocking the airflow channel. In this embodiment, the filter screen 303 is cylindrical, with mesh on the side wall and bottom surface of the cylinder. The top of the cylinder is open and fixed to the top wall of the drying equipment 10 with bolts. An exhaust gas outlet 304 is provided on the upper left side wall of the housing 30. The exhaust gas outlet 304 is connected to the original main exhaust pipe 101 of the drying equipment 10 via an exhaust branch pipe 305. The exhaust gas after heat exchange is discharged downstream for treatment by the exhaust fan 102. A fresh air inlet 306 is provided on the right side of the top wall of the housing 30. A fresh air supply fan 307 is installed above the fresh air inlet 306. The fresh air supply fan introduces the ambient temperature airflow into the plate heat exchanger 201 to exchange heat with the high temperature exhaust gas. A wastewater outlet 308 is provided at the bottom of the housing 30. Wastewater generated during the spray cleaning operation is discharged from the housing 300 through the wastewater outlet 308.

[0026] The front and rear walls of the housing 30 are provided with heat exchanger mounting holes 309 that match the size of the rotary sealing plate 202 of the heat exchanger assembly 20, and bearing seats for mounting the rotating shaft 204 of the heat exchanger assembly 20. A rotary traction motor 310 and a reducer for driving the rotating shaft 204 are mounted on the side of one of the bearing seats. The rotary traction motor 310 is electrically connected to the controller. The heat exchanger assembly 20 is installed inside the housing 30, the rotating shaft 204 is installed in the bearing seat, and the rotary sealing plate 202 can close the heat exchanger mounting holes 309. The plate heat exchanger 201 is in a 45-degree tilt position during normal operation (see reference). Figure 12In this state, the air duct sealing strip 205 contacts the outer wall of the housing 30, dividing the internal space of the housing 30 into a fresh air ventilation duct and an exhaust air ventilation duct. When the plate heat exchanger 201 needs cleaning, the rotary traction motor 310 drives the plate heat exchanger 201 to rotate forward or backward, thereby spraying the internal channels of the plate heat exchanger 201 from various angles through the spray mechanism 40. After cleaning, in order to automatically restore the plate heat exchanger to normal working state, a position sensor is installed on the reducer to detect the stopping position of the plate heat exchanger. The position sensor is connected to the controller. Specifically, the receiver of the position sensor can be installed on the side wall of the housing, and the transmitter of the position sensor can be installed on the rotary sealing plate 202. When the two are opposite each other, the plate heat exchanger is in a 45° working position. After the cleaning process is completed, the rotary traction motor 310 rotates forward or backward until the receiver receives the signal sent by the transmitter, at which point the rotary traction motor 310 stops. Of course, other types of position sensors can also be used, and their installation position is not limited, as long as they can detect the angle of the plate heat exchanger.

[0027] like Figure 3 As shown, to increase the sealing performance between the rotary sealing plate 202 and the housing 30, a sealing strip base plate 209 is welded to the outer circumference of the rotary sealing plate 202. A sealing strip 210 is installed on the sealing strip base plate 209, and a sealing strip pressure plate 211 is installed above the sealing strip 210. The sealing strip pressure plate 211 and the sealing strip base plate 209 are connected and fixed by bolts to press the sealing strip 210. The sealing strip 210 can be of various types commonly used in the prior art, such as flat type and P type.

[0028] like Figure 5 As shown, to further enhance the sealing performance between the air duct sealing strip 205 of the heat exchanger assembly 20 and the housing 30, a sealing surface 311 is provided at the position where the inner wall of the housing 30 contacts the air duct sealing strip 205. When the plate heat exchanger 201 is in the working state, the air duct sealing strip 205 and the sealing surface 311 are tightly fitted, effectively preventing air leakage and ensuring that the hot and cold sources do not mix. The sealing surface 311 can be set to different shapes, such as trapezoidal, square, triangular or semi-circular, depending on the gap between the housing 30 and the air duct sealing strip 205. In this embodiment, isosceles trapezoidal sealing surfaces 311 are provided on the left and right side walls of the housing 30. The bottom surface of the housing 30 can directly contact and seal with the air duct sealing strip 205, so no sealing surface 311 is provided. The top surface of the housing 30 can be opened to facilitate the assembly and maintenance of internal equipment, so a crossbeam 312 is installed on the top of the housing 30 to form a sealing surface 311 that cooperates with the air duct sealing strip 205.

[0029] like Figure 2 , Figure 7As shown, the spraying mechanism 40 includes a spray pipe 401, a spray pipe mounting plate 402, and a spray pipe fixing plate 403. The spray pipe 401 is connected to a water source via a water pipe, and multiple nozzles 404 are provided on the spray pipe 401. The spray pipe mounting plate 402 is bolted or welded to the inner side of the rear side wall of the housing 30. The spray pipe mounting plate 402 is provided with a groove 405, and a pipe cap that can be inserted into the groove 405 is provided at one end of the spray pipe 401. The spray pipe fixing plate 403 is welded to the other end of the spray pipe 401. A spray pipe mounting hole is provided on the front side wall of the housing 30. The pipe cap of the spray pipe 401 is inserted into the housing 30 through the spray pipe mounting hole and embedded in the groove 405. Then, the spray pipe fixing plate 403 is fixed to the housing 30 with bolts, thus completing the assembly of the spraying mechanism 40. The specific number of spray mechanisms 40 can be adjusted according to the size of the plate ventilation and the cleaning effect. Usually, 1-4 sets can achieve a good cleaning effect. In this embodiment, two sets are set.

[0030] To prevent cleaning water from entering the drying equipment 10 during the spray cleaning process, baffles 313 are installed on the left and right side walls of the housing 30 at the exhaust gas inlet 302 and the fresh air outlet 301. The baffles 313 are located above the exhaust gas inlet 302 and the fresh air outlet 301, forming an angle of 20-45 degrees with the left / right side walls of the housing 30. This effectively blocks the water mist sprayed from the spray pipe 401 from entering the drying equipment 10 from the exhaust gas inlet 302 and the fresh air outlet 301, preventing contamination of the materials to be dried. Simultaneously, the bottom wall of the housing 30 is provided with a bottom inclined plate 314 that slopes towards the wastewater outlet 308, ensuring that wastewater can flow smoothly out of the housing 30. Figure 8 As shown, a waterproof fog louver 3061 is also provided at the fresh air inlet 306 to prevent water vapor from overflowing from the fresh air inlet 306.

[0031] like Figure 2 , Figure 9 , Figure 10As shown, the backflushing cleaning mechanism 50 includes an exhaust gas backflushing motor 501, a driving gear 502, a driven gear 503, a bearing assembly 504, a rotary joint 505, and an exhaust gas backflushing pipe 506. The exhaust gas backflushing motor 501 is fixed to the top of the exhaust gas inlet 302 via a backflushing connector 507. A bearing seat is also provided inside the backflushing connector 507, and the bearing assembly 504 is installed inside the bearing seat. The inner ring of the bearing assembly 504 is connected to the exhaust gas backflushing pipe connecting bushing 508. The lower end of the exhaust gas backflushing pipe connecting bushing 508 is connected to the exhaust gas backflushing pipe 506, and an air jet nozzle 509 is provided at the lower end of the exhaust gas backflushing pipe 506. The outer ring of the bearing assembly 504 is connected to the rotary joint 505. The rotary joint 505 has a gas flow hole that communicates with the exhaust gas backflushing pipe 506. The gas flow hole is connected to an air source via an air pipe, and the air source provides compressed air to the air jet nozzle 509. The output shaft of the exhaust gas backflush motor 501 is connected to the drive gear 502, and the driven gear 503 is fitted on the exhaust gas backflush pipe connecting bushing 508. The drive gear 502 and the driven gear 503 mesh.

[0032] The air nozzles 509 are configured in multiple groups, spraying air at different angles along the vertical direction. In this embodiment, three groups of air nozzles 509 are configured: one group is horizontally positioned, one group is tilted downwards at 45°, and one group is tilted downwards at 30°. The system can be set to perform daily scheduled cleaning via a controller, or a fixed cleaning frequency can be set for automatic cleaning at fixed intervals. When the filter cleaning program 303 is started, the exhaust gas backflush motor 501 starts, and simultaneously opens the air source valve to supply compressed air to the exhaust gas backflush pipe 506. The exhaust gas backflush motor 501 drives the drive gear 502 to rotate, which in turn drives the driven gear 503 to rotate. The driven gear 503 drives the exhaust gas backflush pipe connecting bushing 508 and the exhaust gas backflush pipe 506 connected below to rotate. The air nozzles 509 then rotate 360° and spray compressed air at different vertical heights, achieving a comprehensive cleaning of the filter 303. During the cleaning process, the drying equipment 10 can operate normally without affecting the production process.

[0033] To enable water reuse in the spray system 40 and improve cleaning efficiency, an oil separator 60 is also installed. For example... Figure 11As shown, the oil separator 60 includes a water tank 601. A partition 602 is provided in the middle of the water tank 601 to divide the internal space into a primary water tank 6011 and a secondary water tank 6012. A connecting hole 6021 is provided at the lower part of the partition 602. The side wall of the primary water tank 6011 is equipped with a steam heating pipe 603, an overflow pipe 604, and a water inlet 605. The steam heating pipe 603 is connected to a steam source via a pipeline to raise the water temperature. The water temperature is then increased by spraying hot water onto the plate heat exchanger 201, which effectively dissolves oil and improves the cleaning effect. To effectively control the water temperature, a water supply temperature sensor 607 electrically connected to the controller is also installed inside the water tank 601. The overflow pipe 604 is located at the top of the water tank 601. If the water level exceeds the maximum point, water can flow out through the overflow pipe 604. The water inlet 605 is connected to the water source via a water pipe and a solenoid valve. At the same time, a liquid level sensor electrically connected to the controller is installed inside the water tank 601. When the liquid level is lower than the preset minimum liquid level, the solenoid valve opens to add water through the water inlet 605. When the liquid level reaches the preset maximum liquid level, water addition stops.

[0034] A linear vibrating screen 70 is also installed on the upper end of the primary water tank 6011. The linear vibrating screen 70 includes a screen 701, which is inclined and its opening is located outside the water tank 601. The bottom of the screen 701 is connected to the water tank 601 by a spring 703, and a driving device 702 is provided to drive the screen 701 to vibrate. The wastewater outlet 308 of the gas-to-gas heat exchanger is connected to the upper part of the linear vibrating screen 70 via a wastewater pipe. The linear vibrating screen 70 removes impurities from the wastewater and discharges the impurities to a fixed location for collection. A water supply pipe 608 is provided on the side wall of the secondary water tank 6012. The water supply pipe 608 is connected to the spray pipe 401 of the spray mechanism 40 via a water pump 609 to supply water to the spray mechanism 40.

[0035] An oil sludge removal machine 80 is also installed inside the primary water tank 6011. The oil sludge removal machine 80 includes a drive roller located above the water surface and a driven roller 802 located below the water surface. The drive roller is driven to rotate by a drive device. A belt 803 connects the drive roller and the driven roller 802. An oil scraper is provided on one side of the drive roller to scrape the belt 803, and an oil collection trough 801 is provided below the oil scraper. During the operation of the oil sludge removal machine 80, the oil floating on the water surface in the primary water tank 6011 adheres to the belt 803 and is then scraped into the oil collection trough 801 for collection and storage by the oil scraper.

[0036] To automatically monitor the heat exchange efficiency of the gas-to-gas heat exchanger and achieve automatic cleaning, temperature sensors 315 electrically connected to the controller are installed at the fresh air inlet 306, fresh air outlet 301, exhaust gas inlet 302, and exhaust gas outlet 304. When the temperature difference between exhaust gas inlet 302 and exhaust gas outlet 304, or the temperature difference between fresh air outlet 301 and fresh air inlet 306, is less than a preset value, it is determined that the plate heat exchanger 201 needs cleaning. Personnel can choose to stop the machine at a suitable time for heat exchanger cleaning and maintenance. (Refer to...) Figure 13 During maintenance, the heat exchanger assembly 20 rotates continuously at low speed under the traction of the rotary traction motor 310. The water pump 609 transports the hot water in the secondary water tank 6012 to the spray pipe 401 through the water supply pipe 608. The high-temperature and high-pressure water is continuously sprayed onto the plate heat exchanger 201 through the spray pipe 401, cleaning away impurities, lint, oil stains and other substances that cause the equipment to lose efficiency. The above-mentioned debris is discharged along the wastewater outlet 308 and enters the subsequent equipment for further processing.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A self-cleaning waste heat recovery system, characterized in that: It includes one or more sets of gas-to-gas heat exchangers installed on the drying equipment, wherein the gas-to-gas heat exchanger includes a heat exchanger assembly, a housing, a spray mechanism and a backflushing cleaning mechanism; The heat exchanger assembly includes a square plate heat exchanger, with circular rotating sealing plates connected to both ends of the plate heat exchanger, and a rotating shaft installed at the center of the rotating sealing plate; air duct sealing strips are installed at the four edges of the vertical rotating sealing plate of the plate heat exchanger. The housing is equipped with a fresh air inlet, a fresh air outlet, an exhaust gas inlet, and an exhaust gas outlet. A wastewater outlet is located at the bottom of the housing, and the exhaust gas outlet is connected to an exhaust fan via a pipeline. A filter screen is installed at the lower end of the exhaust gas inlet, and a back-flushing cleaning mechanism is installed inside the filter screen. The front and rear walls of the housing are equipped with heat exchanger mounting holes that match the rotating sealing plate and bearing seats for supporting the rotating shaft. A rotating traction motor for driving the rotating shaft is installed on the side of one of the bearing seats. When the heat exchanger assembly is installed in the housing at a 45-degree angle, the air duct sealing strip contacts the outer wall of the housing to form a fresh air ventilation duct and an exhaust gas ventilation duct. The spraying mechanism includes a spray pipe installed on the upper part of the box, which is connected to a water source via a water pipe, and has multiple nozzles on it.

2. The self-cleaning waste heat recovery system according to claim 1, characterized in that: The back-blowing cleaning mechanism includes an exhaust gas back-blowing pipe, an exhaust gas back-blowing motor, and a rotary joint. The lower end of the exhaust gas back-blowing pipe is connected to an air nozzle, and the upper end of the exhaust gas back-blowing pipe is connected to a back-blowing pipe connecting bushing. A bearing assembly is installed above the back-blowing pipe connecting bushing and connected to the inner ring of the bearing assembly. A driven gear is also fitted on the back-blowing pipe connecting bushing. The exhaust gas back-blowing motor and the rotary joint are fixed on the exhaust gas inlet. The output shaft of the exhaust gas back-blowing motor is connected to a driving gear meshing with the driven gear. The rotary joint is connected to the outer ring of the bearing assembly and is connected to an air source via an air pipe.

3. The self-cleaning waste heat recovery system according to claim 2, characterized in that: The jet nozzles are configured in multiple groups, each spraying air at different angles along the vertical direction.

4. The self-cleaning waste heat recovery system according to claim 1, characterized in that: A sealing strip base plate is welded to the circumferential surface of the rotating sealing plate, and a sealing strip is installed on the sealing strip base plate and pressed tightly by the sealing strip pressure plate.

5. The self-cleaning waste heat recovery system according to claim 1, characterized in that: A spray pipe mounting plate is installed on the inner side of the rear side wall of the box. The spray pipe mounting plate is provided with a groove. One end of the spray pipe is provided with a pipe cap that can be inserted into the groove. A spray pipe fixing plate is welded to the other end of the spray pipe. A spray pipe mounting hole is provided on the front side wall of the box. The pipe cap of the spray pipe is inserted into the box through the spray pipe mounting hole and embedded in the groove. The spray pipe fixing plate is fixed to the box with bolts.

6. The self-cleaning waste heat recovery system according to claim 1, characterized in that: The rotating shaft is welded to the load-bearing connecting plate, which is then bolted to the rotating sealing plate.

7. The self-cleaning waste heat recovery system according to claim 1, characterized in that: The inner wall of the box is provided with a sealing surface that contacts the air duct sealing strip.

8. The self-cleaning waste heat recovery system according to claim 1, characterized in that: Temperature sensors are installed at the fresh air inlet, fresh air outlet, exhaust gas inlet, and exhaust gas outlet.

9. The self-cleaning waste heat recovery system according to claim 1, characterized in that: It also includes an oil separator, which includes a water tank. The water tank is divided into a primary water tank and a secondary water tank by a partition in the middle. A connecting hole is provided at the bottom of the partition. A steam heating pipe, an overflow pipe and a water inlet are installed on the side wall of the primary water tank. A linear vibrating screen is also installed on the primary water tank. The wastewater outlet is connected to the top of the linear vibrating screen through a wastewater pipe, and the linear vibrating screen removes impurities from the wastewater. A water supply pipe and a water pump connected to the spray pipe are provided on the side wall of the secondary water tank.

10. The self-cleaning waste heat recovery system according to claim 9, characterized in that: The primary water tank is also equipped with an oil skimmer, which includes an active roller located above the water surface and a driven roller located below the water surface. A belt connects the active roller and the driven roller. An oil scraper is provided on one side of the active roller to scrape the belt, and an oil receiving groove is provided at the bottom of the oil scraper.

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