A waste heat recovery device for treating low-NOx combustion flue gas in boilers

Abstract

This invention relates to the field of flue gas treatment technology, specifically a waste heat recovery device for treating low-NOx combustion flue gas in boilers. The device housing has an inlet and an outlet at its front and rear ends, respectively. A heat exchange tube bundle is installed inside the housing, with connecting pipes movably mounted on it. A drive motor is fixedly installed on the outer wall of the inlet. A filtering inlet mechanism is located within the inlet and is used to improve the purity and efficiency of the incoming flue gas. A reciprocating heat exchange mechanism is located inside the housing. By optimizing and improving existing low-NOx combustion flue gas waste heat recovery equipment—characterized by poor adaptability to filtration and cleaning, easy degradation of heat exchange efficiency, and weak structural linkage—this invention offers multiple practical advantages and effectively adapts to the complex flue gas conditions under variable load boiler operation.

Description

Technical Field

[0001] This invention relates to the field of flue gas treatment technology, specifically to a waste heat recovery device for treating low-NOx combustion flue gas from boilers. Background Technology

[0002] Currently, low-NOx combustion technology has been widely applied in the field of industrial boiler flue gas treatment. This technology can effectively reduce the generation of nitrogen oxides during boiler combustion, meeting the basic requirements for environmental protection emissions of industrial flue gas. The flue gas generated during low-NOx combustion in boilers contains a certain amount of ultrafine fly ash and sticky dust, and acidic wet impurities are easily generated during flue gas cooling. These impurities have strong adhesion and can have many adverse effects on subsequent flue gas treatment and waste heat recovery operations. To achieve the resource utilization of flue gas waste heat, most boilers on the market are equipped with waste heat recovery devices. These devices extract waste heat from the flue gas through heat exchange structures, reducing energy consumption in flue gas emissions and improving the overall energy efficiency of boiler operation.

[0003] In existing technologies, the flue gas inlet filtration structure of traditional waste heat recovery devices is relatively simple, mostly using fixed filter screens for basic filtration, which can only intercept larger dust particles in the flue gas. For the ultrafine, sticky dust contained in low-NOx combustion flue gas, fixed filter screens are prone to ash accumulation and clogging. Furthermore, the cleaning structure of conventional filtration equipment is mostly a fixed pressure contact cleaning structure, which is difficult to adjust the cleaning intensity according to changes in flue gas intake volume and dust concentration. After long-term operation, this easily leads to a decrease in filtration flux and insufficient intake air purity, which not only affects flue gas intake efficiency, but also allows insufficiently filtered ultrafine dust to enter the heat exchange structure with the flue gas, causing adhesion and contamination of the heat exchange components.

[0004] Meanwhile, traditional waste heat recovery devices mostly employ fixed installation structures for their heat exchanger tube bundles. The heat exchange between flue gas and the tube bundles is relatively simple, and the tube walls, constantly in contact with dust-laden, wet flue gas, easily accumulate dust, impurities, and acidic scale, increasing thermal resistance and gradually weakening the equipment's waste heat exchange efficiency. Most traditional devices lack dynamic cleaning and heat exchange enhancement structures adapted to the heat exchanger tube bundles, relying solely on static heat exchange for waste heat recovery. Impurities on the tube walls are difficult to detach and accumulate, continuously affecting heat exchange performance and increasing the workload and costs of daily maintenance and cleaning.

[0005] To address the aforementioned issues, innovative designs are urgently needed based on existing approaches. Summary of the Invention

[0006] The purpose of this invention is to provide a waste heat recovery device for treating low-NOx combustion flue gas in boilers, so as to solve the problems mentioned in the background art. The technical solution of this invention provides a solution that is significantly different from the existing technology, which is too simplistic.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a waste heat recovery device for treating low-NOx combustion flue gas in a boiler, comprising a device housing, an air inlet and an air outlet respectively provided at the front and rear ends of the device housing, a heat exchange tube bundle provided inside the device housing, a connecting pipe movably installed on the heat exchange tube bundle, and a drive motor fixedly installed on the outer wall of the air inlet. A filtering air intake mechanism is provided in the air intake port, and the filtering air intake mechanism is used to improve the purity and efficiency of the flue gas intake. A reciprocating heat exchange mechanism is disposed inside the device housing and is used to improve the heat exchange efficiency of the heat exchange tube bundle.

[0008] Preferably, the air intake filtration mechanism includes a filter screen disposed in the air intake. The filter screen is cylindrical in side view, and the right end of the filter screen is connected to the output end of the drive motor.

[0009] Preferably, the left end of the filter screen is connected to a rotating disk via a rod, and an oil cylinder is provided inside the rotating disk. An abutment rod is slidably installed on the upper limit of the rotating disk, and a piston rod is elastically provided on the oil cylinder and fixedly connected to the abutment rod.

[0010] Preferably, the upper and lower ends of the filter screen are fitted with cleaning scrapers, the cleaning scrapers are connected to pressure springs, the other end of the pressure springs is fitted with a squeezing plate, the squeezing plate is connected to a piston rod, and the piston rod is matched with an oil cylinder, which is symmetrically arranged in the air inlet.

[0011] Preferably, the air intake filtration mechanism further includes a swing plate, which is rotatably mounted in the device housing, and a connecting plate is fixedly mounted on the swing plate.

[0012] Preferably, the connecting plate is disposed in the internal cavity of the air inlet, and a sliding groove is provided on the connecting plate, in which an abutment rod is slidably installed.

[0013] Preferably, the reciprocating heat exchange mechanism includes a moving block, which is slidably installed inside the device housing and fixedly installed at the lower end of the heat exchange tube bundle. The moving block has symmetrically distributed toothed blocks arranged at equal intervals in the bottom cavity of the moving block, and impact plates are symmetrically arranged at the left and right ends of the moving block.

[0014] Preferably, a rotary motor is fixedly installed inside the housing of the device, and a half gear is connected to the output end of the rotary motor. The half gear meshes with a toothed block, and rubber protrusions are evenly distributed on the surface of the impact plate.

[0015] Preferably, a tension spring is connected to the rear end of the impact plate, and a movable plate is connected to the other end of the tension spring. The movable plate is fixedly connected to the piston rod three, and the oil cylinder three, which is matched with the piston rod three, is connected to the oil cylinder one and the oil cylinder two respectively through the liquid delivery hose.

[0016] Preferably, the reciprocating heat exchange mechanism further includes an electric push rod, which is disposed inside the device housing. The top end of the electric push rod is fitted with a trapezoidal extrusion block via a connector, and the inclined surface of the extrusion block abuts against the movable plate.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This device uses a dynamic rotating filter structure to replace the traditional fixed filter screen, which can precisely adapt to the complex flue gas conditions generated by low-NOx combustion in boilers. It can effectively intercept ultrafine suspended fly ash, highly viscous dust, and acidic condensed impurities entrained in the flue gas. Compared with the single mode of static filtration of traditional fixed filters, the rotating filter screen can adjust the flue gas contact angle through continuous rotation, effectively expanding the filtration contact area, stabilizing the purity and flow rate of the flue gas entering the equipment, and avoiding the problems of local ash accumulation and uneven filtration of conventional filters. Meanwhile, the device is equipped with an adaptive and adjustable elastic scraper cleaning structure. Relying on the hydraulic linkage transmission structure, it realizes autonomous control of cleaning pressure. It can flexibly adapt the cleaning force according to the real-time changes in flue gas dust concentration, humidity and viscosity, adapt to the variable flue gas environment under the switching of high and low boiler loads, continuously remove stubborn ash and scale layers attached to the filter screen surface, fundamentally improve the ash accumulation and clogging problems that are prone to occur in long-term operation of the filter screen, ensure the continuous and stable operation of flue gas filtration, effectively block various impurities from flowing into the heat exchange cavity with the flue gas, avoid ash accumulation, pollution, blockage and corrosion on the heat exchange tube wall, and create a clean and stable operating environment for downstream waste heat exchange operations. In addition, while the filter screen rotates, the swing mechanism drives the swing to reciprocate inside the device shell, disturbing the gas and improving the heat exchange efficiency of the device. 2. This device abandons the traditional fixed installation structure of heat exchange tube bundles and adopts a dynamic heat exchange structure that can reciprocate. The high-frequency reciprocating motion of the entire tube bundle disturbs the internal flue gas flow, effectively enhancing the contact between the flue gas and the heat exchange tube wall, improving the sufficiency of waste heat exchange, and further optimizing the overall waste heat recovery efficiency. Simultaneously, a dedicated elastic impact-coordinated structure generates continuous micro-vibrations through regular impacts during the tube bundle's reciprocating motion. This effectively shakes off dust deposits and acidic scale adhering to the heat exchange tube wall, significantly reducing heat exchange resistance and alleviating the problem of continuous heat exchange effect degradation after long-term operation. This also significantly reduces the frequency and cost of daily manual cleaning, maintenance, and repair. Attached Figure Description

[0018] Figure 1This is a three-dimensional structural diagram of the present invention; Figure 2 This is a schematic cross-sectional view of the air inlet structure of the present invention; Figure 3 This is a schematic diagram of the connection structure between the swing plate and the connecting plate of the present invention; Figure 4 This is a schematic cross-sectional view of the upper part of the air inlet of the present invention; Figure 5 This is a schematic diagram of the internal structure of the device housing of the present invention; Figure 6 This is a schematic cross-sectional view of the housing of the device of the present invention; Figure 7 This is a schematic cross-sectional view of the bottom of the housing of the device of the present invention; Figure 8 This is a bottom view of the moving block structure of the present invention; Figure 9 This is a schematic diagram of the connection structure between the electric push rod and the extrusion block of the present invention.

[0019] In the diagram: 1. Device housing; 2. Air inlet; 3. Air outlet; 4. Heat exchange tube bundle; 5. Connecting pipe; 6. Drive motor; 7. Filter screen; 8. Rotary disc; 9. Oil cylinder one; 10. Abutment rod; 11. Piston rod one; 12. Cleaning scraper; 13. Pressure spring; 14. Extrusion plate; 15. Piston rod two; 16. Oil cylinder two; 17. Swing plate; 18. Connecting plate; 19. Sliding groove; 20. Moving block; 21. Tooth block; 22. Impact plate; 23. Rotary motor; 24. Half gear; 25. Tension spring; 26. Movable plate; 27. Piston rod three; 28. Oil cylinder three; 29. ​​Electric push rod; 30. Extrusion block.

[0020] Please see Figures 1-9 The present invention provides a technical solution: a waste heat recovery device for treating low-NOx combustion flue gas in a boiler, comprising a device housing 1, an air inlet 2 and an air outlet 3 respectively provided at the front and rear ends of the device housing 1, a heat exchange tube bundle 4 provided inside the device housing 1, a connecting pipe 5 movably installed on the heat exchange tube bundle 4, and a drive motor 6 fixedly installed on the outer wall of the air inlet 2. The air intake filter is installed in the air inlet 2. The air intake filter is used to improve the purity and efficiency of the flue gas. The reciprocating heat exchange mechanism is located inside the housing 1 of the device and is used to improve the heat exchange efficiency of the heat exchange tube bundle 4.

[0021] In one embodiment of the present invention, the air intake filtration mechanism includes a filter screen 7, which is disposed in the air intake 2. The filter screen 7 is cylindrical in side view, and the right end of the filter screen 7 is connected to the output end of the drive motor 6.

[0022] In one embodiment of the present invention, the left end of the filter screen 7 is connected to a rotating disk 8 via a rod. An oil cylinder 9 is provided inside the rotating disk 8. An abutment rod 10 is slidably installed on the upper limit of the rotating disk 8. A piston rod 11 is elastically provided on the oil cylinder 9 and is fixedly connected to the abutment rod 10.

[0023] In one embodiment of the present invention, cleaning scrapers 12 are attached to the upper and lower ends of the filter screen 7. A pressure spring 13 is connected to the cleaning scraper 12. A squeezing plate 14 is installed at the other end of the pressure spring 13. A piston rod 15 is connected to the squeezing plate 14. An oil cylinder 16 is symmetrically arranged in the air inlet 2.

[0024] As one embodiment of the present invention, the air intake filter mechanism further includes a swing plate 17, which is rotatably mounted in the device housing 1, and a connecting plate 18 is fixedly mounted on the swing plate 17.

[0025] In one embodiment of the present invention, the connecting plate 18 is disposed in the internal cavity of the air inlet 2, and a sliding groove 19 is provided on the connecting plate 18, and an abutment rod 10 is slidably installed in the sliding groove 19.

[0026] The drive motor 6 on the outside of the air inlet 2 drives the cylindrical filter screen 7 to rotate continuously, dynamically intercepting the flue gas entering the air inlet 2, effectively filtering out ultrafine fly ash and sticky dust in the flue gas, and preventing impurities from entering the heat exchange area and causing pollution. During the operation of the screen, the oil cylinder 16 inside the air inlet 2, through the piston rod 15, the extrusion plate 14 and the pressure spring 13, keeps the cleaning scraper 12 in constant contact with the screen surface, scraping off surface dust in real time. At the same time, the rotation of the filter screen 7 drives the end rotating disk 8 to rotate synchronously, and the abutment rod 10 slides within the sliding groove 19 of the connecting plate 18, which in turn drives the swing plate 17 to swing back and forth, diverting and disturbing the flue gas, optimizing the flue gas intake efficiency and flow uniformity. When the flue gas load increases and the dust concentration rises, the device transmits oil pressure through the hydraulic linkage system, automatically increasing the scraper clamping cleaning force and expanding the swing amplitude of the swing plate 17.

[0027] As one embodiment of the present invention, the reciprocating heat exchange mechanism includes a moving block 20, which is slidably installed inside the device housing 1 and fixedly installed at the lower end of the heat exchange tube bundle 4. The bottom cavity of the moving block 20 is symmetrically arranged with equally spaced toothed blocks 21, and the left and right ends of the moving block 20 are symmetrically arranged with impact plates 22.

[0028] In one embodiment of the present invention, a rotary motor 23 is fixedly installed inside the device housing 1. The output end of the rotary motor 23 is connected to a half gear 24, which meshes with a toothed block 21. Rubber protrusions are provided at equal intervals on the surface of the impact plate 22.

[0029] In one embodiment of the present invention, a tension spring 25 is connected to the rear end of the impact plate 22, and a movable plate 26 is connected to the other end of the tension spring 25. The movable plate 26 is fixedly connected to the piston rod 27. The oil cylinder 28, which is matched with the piston rod 27, is connected to the oil cylinder 9 and the oil cylinder 16 through the infusion hose.

[0030] As one embodiment of the present invention, the reciprocating heat exchange mechanism further includes an electric push rod 29, which is disposed inside the device housing 1. The top end of the electric push rod 29 is fitted with a trapezoidal extrusion block 30 via a connector, and the inclined surface of the extrusion block 30 abuts against the movable plate 26.

[0031] After the flue gas enters the housing 1 of the device, the rotary motor 23 drives the half gear 24 to rotate continuously. The intermittent meshing of the half gear 24 with the bottom toothed block 21 of the moving block 20 causes the moving block 20 and the top-fixed heat exchange tube bundle 4 to perform regular left-right reciprocating linear motion, dynamically disturbing the flue gas flow and enhancing the contact heat exchange effect between the flue gas and the heat exchange tube bundle 4. During the reciprocating movement of the tube bundle, the impact plates 22 at both ends of the moving block 20 regularly impact the housing structure. Combined with the tension spring 25 and the movable plate 26, this forms an elastic buffer vibration, transmitting the slight vibration to the entire heat exchange tube bundle 4, weakening the adhesion of impurities and achieving automatic scaling and ash removal from the tube walls. Simultaneously, the oil cylinder 3 28 is interconnected with oil cylinder 1 9 and oil cylinder 2 16 to form a hydraulic linkage. According to changes in the flue gas load, the trapezoidal extrusion block 30 can be adjusted by the electric push rod 29 to change the contact position and alter the vibration intensity of the impact plate 22.

[0032] Working principle: During actual operation, the flue gas generated by the low-NOx combustion of the boiler is introduced into the equipment through the air inlet 2 at the front end of the device shell 1. After purification and heat exchange, the low-temperature clean flue gas is discharged from the air outlet 3 at the rear end of the shell, completing the entire flue gas treatment and waste heat recovery process.

[0033] After the flue gas enters the inlet 2, the drive motor 6 starts and drives the cylindrical filter screen 7 to rotate continuously, dynamically filtering the flowing flue gas. This effectively intercepts impurities such as ultrafine fly ash and sticky dust carried in the flue gas, preventing impurities from directly entering the heat exchange area and causing accumulation and pollution. During the rotation of the filter screen 7, the oil cylinders 16, which are symmetrically arranged inside the inlet 2, drive the piston rod 15 and the extrusion plate 14 to move. Together with the pressure spring 13, the cleaning scraper 12 is always in contact with the surface of the filter screen 7, scraping off the accumulated dust and impurities on the screen surface in real time. At the same time, the rotating disk 8 connected to the left end of the filter screen 7 rotates synchronously with it. The abutment rod 10 inside the rotating disk 8 slides within the sliding groove 19 of the connecting plate 18 and, together with the swing plate 17, swings up and down inside the device housing 1, disturbing the gas and pushing it towards the inside of the device housing 1. At the same time, the movement of the swing plate 17 diverts the gas, preventing the gas from exchanging heat at a single location for a long time and improving the overall heat exchange efficiency of the device. After filtration and purification, the clean flue gas enters the internal cavity of the device housing 1 and comes into full contact with the heat exchange tube bundle 4 and the matching connecting pipe 5 to complete the heat exchange of the flue gas waste heat. During the heat exchange process, the rotary motor 23 inside the device housing 1 drives the half gear 24 to rotate continuously. Through the intermittent meshing transmission between the half gear 24 and the bottom tooth block 21 of the moving block 20, the moving block 20 and the heat exchange tube bundle 4 fixed at the top are driven to make a stable left and right reciprocating linear motion.

[0034] During the reciprocating movement of the heat exchange tube bundle 4, the impact plates 22 at both ends of the moving block 20 continuously and regularly impact the internal structure of the shell. This, combined with the tension spring 25 and the movable plate 26, creates an elastic buffering effect, transmitting the slight vibrations to the entire heat exchange tube bundle 4. This reduces the adhesion of dust and acid scale to the tube walls, achieving real-time self-cleaning of the heat exchange structure. Simultaneously, the oil cylinder 3 28 forms a hydraulic linkage system with oil cylinder 1 9 and oil cylinder 2 16 via a delivery hose. When a large amount of flue gas enters, the electric push rod 29 drives the trapezoidal extrusion block 30 to move, changing the contact position between the movable plate 26 and the extrusion block 30. This causes the extrusion block 30 to move to both sides, allowing the movable plate 26, under the action of the tension spring 25, to extrude oil from inside the oil cylinder 3 28 through the delivery hose to oil cylinder 1 9 and oil cylinder 2 16. The piston rod 2 15 then pushes the extrusion plate 14 against the pressure spring 13. Applying pressure increases the clamping force of the cleaning scraper 12 on the filter screen 7, improving the cleaning effect. At the same time, the piston rod 11 pushes the abutment rod 10 to slide away from its center in the rotating disk 8, thereby causing the abutment rod 10, which is limited to sliding in the sliding groove 19, to rotate with a larger diameter. This drives the swing plate 17 to swing back and forth with a larger amplitude, further improving the air intake efficiency. Thus, the elastic abutment force and vibration intensity of the impact plate 22 can be adaptively adjusted according to the flue gas load and equipment operating status to meet the working conditions of different flue gas dust concentrations, and continuously ensure heat exchange efficiency and equipment operating stability.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations 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 scope of the present invention.

Claims

1. A waste heat recovery device for treating low-NOx combustion flue gas in boilers, comprising a device housing (1), characterized in that: The device housing (1) has an air inlet (2) and an air outlet (3) at its front and rear ends, respectively. A heat exchange tube bundle (4) is provided inside the device housing (1). A connecting pipe (5) is movably installed on the heat exchange tube bundle (4). A drive motor (6) is fixedly installed on the outer wall of the air inlet (2). A filter intake mechanism is provided in the air inlet (2). The filter intake mechanism is used to improve the purity and efficiency of the flue gas intake. A reciprocating heat exchange mechanism is installed inside the device housing (1) and is used to improve the heat exchange efficiency of the heat exchange tube bundle (4).

2. The waste heat recovery device for treating low-NOx combustion flue gas in a boiler according to claim 1, characterized in that: The air intake filtration mechanism includes a filter screen (7), which is disposed in the air intake (2). The filter screen (7) is cylindrical in side view, and the right end of the filter screen (7) is connected to the output end of the drive motor (6).

3. The waste heat recovery device for treating low-NOx combustion flue gas in a boiler according to claim 2, characterized in that: The left end of the filter screen (7) is connected to a rotating disk (8) via a rod. An oil cylinder (9) is installed inside the rotating disk (8). An abutment rod (10) is slidably installed on the upper limit of the rotating disk (8). A piston rod (11) is elastically installed on the oil cylinder (9) and fixedly connected to the abutment rod (10).

4. The waste heat recovery device for treating low-NOx combustion flue gas in a boiler according to claim 3, characterized in that: The filter screen (7) is fitted with cleaning scrapers (12) at both ends. A pressure spring (13) is connected to the cleaning scraper (12). A squeezing plate (14) is installed at the other end of the pressure spring (13). A piston rod (15) is connected to the squeezing plate (14). The oil cylinder (16) matched with the piston rod (15) is symmetrically arranged in the air inlet (2).

5. A waste heat recovery device for treating low-NOx combustion flue gas in a boiler according to claim 4, characterized in that: The air intake filter mechanism also includes a swing plate (17), which is rotatably installed in the housing (1) of the device, and a connecting plate (18) is fixedly installed on the swing plate (17).

6. A waste heat recovery device for treating low-NOx combustion flue gas in a boiler according to claim 5, characterized in that: The connecting plate (18) is disposed in the internal cavity of the air inlet (2), and a sliding groove (19) is provided on the connecting plate (18), and an abutment rod (10) is slidably installed in the sliding groove (19).

7. The waste heat recovery device for treating low-NOx combustion flue gas in a boiler according to claim 1, characterized in that: The reciprocating heat exchange mechanism includes a moving block (20), which is slidably installed inside the housing (1) of the device. The moving block (20) is fixedly installed at the lower end of the heat exchange tube bundle (4). The bottom cavity of the moving block (20) is symmetrically arranged with equally spaced toothed blocks (21), and the left and right ends of the moving block (20) are symmetrically arranged with impact plates (22).

8. A waste heat recovery device for treating low-NOx combustion flue gas in a boiler according to claim 7, characterized in that: A rotary motor (23) is fixedly installed inside the housing (1) of the device. The output end of the rotary motor (23) is connected to a half gear (24). The half gear (24) meshes with the tooth block (21). Rubber protrusions are provided at equal intervals on the surface of the impact plate (22).

9. A waste heat recovery device for treating low-NOx combustion flue gas in a boiler according to claim 8, characterized in that: The rear end of the impact plate (22) is connected to a tension spring (25), and the other end of the tension spring (25) is connected to a movable plate (26). The movable plate (26) is fixedly connected to the piston rod three (27). The oil cylinder three (28) provided with the piston rod three (27) is connected to the oil cylinder one (9) and the oil cylinder two (16) respectively through the infusion hose.

10. A waste heat recovery device for treating low-NOx combustion flue gas in a boiler according to claim 9, characterized in that: The reciprocating heat exchange mechanism also includes an electric push rod (29), which is located inside the device housing (1). The top end of the electric push rod (29) is fitted with a trapezoidal extrusion block (30) via a connector. The inclined surface of the extrusion block (30) abuts against the movable plate (26).

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