Energy-saving boiler

Abstract

The invention discloses an energy-saving boiler, and relates to the technical field of boilers, the energy-saving boiler comprises a boiler body and a smoke exhaust pipeline mounted on the boiler body, the energy-saving boiler further comprises an air preheater mounted at the tail end of the smoke exhaust pipeline, and a pair of heat exchange pipe sets distributed in the smoke exhaust direction is mounted in the air preheater; the heat exchange tube set is composed of a plurality of heat exchange tube bundles, expanding parts and reducing parts which are alternately distributed along the axes of the heat exchange tube bundles are arranged on the heat exchange tube bundles, spiral flow deflectors and movable cleaning frames with upper and lower openings are arranged on the inner walls of the reducing parts, and the movable cleaning frames are movably installed in the heat exchange tube set and provided with through holes allowing the heat exchange tube bundles to penetrate through. Annular cleaning turbulent flow pieces corresponding to the heat exchange tube bundles are rotationally installed in the movable cleaning frame. By arranging the movable cleaning frame and a plurality of annular cleaning turbulent flow pieces in the movable cleaning frame, the outer wall of the heat exchange tube bundle can be continuously scraped in the moving process, and compared with a traditional soot blowing mode, the mechanical scraping mode is more thorough in soot cleaning.

Description

Technical Field

[0001] This invention relates to the field of boiler technology, specifically to an energy-saving boiler. Background Technology

[0002] Biomass boilers are core thermal energy equipment in industrial production and heating systems. Their thermal efficiency directly affects energy consumption and operating costs. Flue gas heat loss is one of the most significant heat losses in boilers. In order to recover waste heat from the flue gas and achieve energy saving while reducing flue gas temperature, an air preheater is usually installed in the flue gas duct at the tail end of the boiler. The air preheater exchanges heat between the flue gas and the combustion air. The preheated air enters the furnace, which not only improves the thermal efficiency of the boiler but also improves the combustion conditions of the fuel.

[0003] The existing patent application, with publication number CN118463214A and publication date of August 9, 2024, is titled "An Industrial Boiler Anti-Ashes Tube-Type Air Preheater." This patent includes a preheater hot section formed by several hot-section heat exchange tube bundles at the top, and a preheater cold section formed by several cold-section heat exchange tube bundles at the bottom. It also includes a hot-section steam sootblower with its sootblowing pipe located in the inlet flue at the top of the hot section; a sandwich section located between the hot and cold sections; a sandwich steam sootblower with its sootblowing pipe located in the sandwich section; and a cold-section steam sootblower with its sootblowing pipe located in the outlet flue at the bottom of the cold section. Adjacent cold-section heat exchange tube bundles are arranged in a staggered pattern. This invention uses a sandwiched steam soot blower in the sandwich section and a staggered arrangement of the cold section heat exchange tube bundle to avoid ash bridging in the cold section of the preheater, shorten the steam soot blowing path, and achieve precise ash blowing.

[0004] The above application has shortcomings. Due to the large ash content in boiler flue gas, ordinary boiler air preheaters are prone to ash accumulation when using flue gas to exchange heat with air, and even coal ash blockage can occur, hindering flue gas flow. Although it is possible to further purge the ash between the air preheater tubes by adding a purging device, the airflow coverage of the purging device is limited by the complex structure of the tube bundle gaps. The penetrating power of the purging airflow between the dense tube bundles is insufficient, making it difficult to effectively blow the ash away from the air preheater tube gaps. Secondly, continuous high-pressure purging will lead to increased tube bundle vibration, accelerate metal fatigue, and may cause cracking of the weld between the heat exchange tubes and the tube sheet. Furthermore, when the purging device is used for highly viscous ash, the viscous ash has a stronger adhesion and is not easily removed by the purging airflow, resulting in a more limited ash removal effect, insufficient flue gas heat exchange efficiency, and insufficient utilization of waste heat. Summary of the Invention

[0005] The purpose of this invention is to provide an energy-saving boiler to address the shortcomings of the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An energy-saving boiler includes a boiler body and a flue gas duct installed on the boiler body, and an air preheater installed at the end of the flue gas duct. The air preheater contains a pair of heat exchange tube bundles distributed along the flue gas emission direction. Each heat exchange tube bundle consists of multiple heat exchange tube bundles, and each heat exchange tube bundle has alternating expansion and contraction sections distributed along its axis. The inner wall of the contraction section is provided with spiral guide vanes. A movable cleaning frame with openings at the top and bottom is movably installed in the heat exchange tube bundles and has through holes for the heat exchange tube bundles to pass through. An annular cleaning baffle corresponding to each heat exchange tube bundle is rotatably installed inside the movable cleaning frame. The annular cleaning baffle contacts the outer walls of the expansion and contraction sections respectively. When the movable cleaning frame moves, the annular cleaning baffle alternately scrapes the outer walls of the expansion and contraction sections and rotates under the push of the flue gas, thus playing a baffle role.

[0008] Preferably, the air preheater has a flue gas inlet at the bottom of one side connected to the flue gas duct, a flue gas outlet at the top of the air preheater, a pair of heat exchange tubes distributed vertically inside the air preheater, and an air inlet and an air outlet respectively connected to the two heat exchange tubes on the other side of the air preheater. The air preheater also has a reversing air chamber for connecting the two heat exchange tubes.

[0009] Preferably, tube sheets are fixedly connected to both sides of the heat exchange tube bundle, and the two ends of the heat exchange tube bundle are respectively fixed to two tube sheets. A support frame is fixedly connected inside the air preheater, and the tube sheet is connected to the support frame.

[0010] Preferably, a dual-axis motor is fixedly connected between the two movable cleaning frames. A transmission rod is installed at both ends of the dual-axis motor, and a drive gear is fixedly connected to the end of the transmission rod. A rack that meshes with the bottom of the drive gear is fixedly connected to both sides of the inner wall of the support frame.

[0011] Preferably, the annular cleaning baffle includes a cleaning sleeve rotatably connected to both sides of the inner wall of the movable cleaning frame. Several blades are distributed in annular shape on the outer wall of the cleaning sleeve, and an elastic scraper is movably inserted into the inner wall of the cleaning sleeve. Both sides of the elastic scraper are provided with abutting grooves that abut against the reduced diameter portion.

[0012] Preferably, the cleaning sleeve has a plurality of ash discharge holes distributed in a ring, and the ash discharge holes are staggered from the blades.

[0013] Preferably, both sides of the inner wall of the two movable cleaning frames are vertically slidably mounted with pull rods, and several abutment blocks are vertically distributed on the pull rods. Several receiving grooves that abut and cooperate with each abutment block are opened on the side wall of the movable cleaning frame. A plug-in post is fixedly connected to the middle of the pull rod, and wavy guide grooves for the plug-in post to be inserted are opened horizontally on both sides of the support frame.

[0014] Preferably, a guide plate is fixedly connected to one side of the support frame in the reversing air chamber, and an impeller and a baffle are rotatably installed below the guide plate inside the reversing air chamber. An eccentric shaft is installed at both ends of the impeller, and a connecting rod that is hinged to the eccentric shaft is installed at both ends of the baffle.

[0015] Preferably, the air preheater is provided with an ash hopper at the bottom, a dust filter screen is installed on the top of the ash hopper, and ash discharge grooves are provided on both sides of the dust filter screen. The bottom of one of the movable cleaning frames abuts against the dust filter screen, and a dust removal brush is embedded in the side wall of the movable cleaning frame.

[0016] Preferably, a heat-conducting metal wire is embedded between the spiral guide vane and the heat exchange tube bundle.

[0017] In the above technical solution, by setting a mobile cleaning frame and multiple annular cleaning turbulence components inside it, the outer wall of the heat exchange tube bundle can be continuously scraped during the movement. The mechanical scraping method is more thorough than the traditional soot blowing method, especially effective in removing highly adhesive ash. This process can be carried out automatically during boiler operation without shutdown, ensuring long-term high-efficiency operation of the equipment and fundamentally solving the problems of efficiency reduction and blockage caused by ash accumulation. The annular cleaning turbulence components rotate under the impetus of flue gas and are themselves highly efficient turbulence components. They not only clean the tube wall but also continuously disrupt the laminar boundary layer of the heat exchange tube wall, enhancing the turbulence on the flue gas side, thereby significantly enhancing the heat transfer effect and achieving the synergistic effect of ash removal and heat exchange. The alternating arrangement of the expansion and contraction sections of the heat exchange tube bundle causes periodic changes in the velocity and direction of flue gas and air, further enhancing turbulent heat transfer. The spiral guide vanes in the contraction section guide the air to rotate within the heat exchange tube bundle, further improving the heat transfer coefficient.

[0018] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative only, and are not intended to limit this disclosure.

[0019] This application provides an overview of various implementations or examples of the technology described in this disclosure, and is not a full disclosure of the entire scope or all features of the disclosed technology. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0021] Figure 1 This is a plan view of the overall layout of an energy-saving boiler according to the present invention;

[0022] Figure 2 This is a schematic diagram showing the connection between the flue gas duct and the air preheater in an energy-saving boiler according to the present invention;

[0023] Figure 3 This is a schematic diagram of the structure of an air preheater in an energy-saving boiler according to the present invention;

[0024] Figure 4 This is a schematic diagram of the internal structure of an air preheater in an energy-saving boiler according to the present invention;

[0025] Figure 5 This is a schematic diagram showing the connection between the heat exchange tube assembly and the movable cleaning frame in an energy-saving boiler according to the present invention.

[0026] Figure 6 This is a partial cross-sectional view of a heat exchange tube bundle in an energy-saving boiler according to the present invention;

[0027] Figure 7 This is a schematic diagram of the movable cleaning frame and support frame in an energy-saving boiler according to the present invention;

[0028] Figure 8 This is a schematic diagram of the transmission of the impeller and baffle in an energy-saving boiler according to the present invention;

[0029] Figure 9 This is a schematic diagram of the transmission of an annular cleaning turbulence component in an energy-saving boiler according to the present invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Boiler body; 101. Flue gas duct; 2. Air preheater; 201. Flue gas inlet; 202. Flue gas outlet; 203. Air inlet; 204. Air outlet; 205. Reversing air chamber; 3. Heat exchanger tube assembly; 301. Heat exchanger tube bundle; 302. Expanded diameter section; 303. Reduced diameter section; 304. Spiral guide vane; 305. Tube sheet; 306. Thermally conductive metal wire; 4. Moving cleaning frame; 401. Through hole; 402. Dual-shaft motor; 403. Transmission rod; 404. Drive gear; 405. Receiving tank; 406. Dust removal brush; 5. Annular cleaning baffle; 501. Cleaning sleeve; 502. Blade; 503. Elastic scraper; 504. Abutment groove; 505. Ash discharge hole; 6. Support frame; 601. Rack; 602. Corrugated guide groove; 603. Guide plate; 7. Tie rod; 701. Abutment block; 702. Insertion column; 8. Impeller; 801. Eccentric shaft; 9. Baffle; 901. Connecting rod; 10. Ash hopper; 11. Smoke and dust filter screen; 12. Ash discharge chute. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0033] Please see Figures 1-9 An energy-saving boiler provided in this embodiment of the invention includes a boiler body 1 and a flue gas duct 101 installed on the boiler body 1. It also includes an air preheater 2 installed at the end of the flue gas duct 101. The air preheater 2 contains a pair of heat exchange tube groups 3 distributed along the flue gas emission direction. Each heat exchange tube group 3 consists of multiple heat exchange tube bundles 301, and each heat exchange tube bundle 301 has alternating diameter-expanding sections 302 and diameter-reducing sections 303 distributed along its axis. The inner wall of the diameter-reducing section 303 is provided with spiral guide vanes 304. The movable cleaning frame 4 with a lower opening is movably installed in the heat exchange tube assembly 3, and has a through hole 401 for the heat exchange tube bundle 301 to pass through. Inside the movable cleaning frame 4, there is an annular cleaning baffle 5 corresponding to each heat exchange tube bundle 301. The annular cleaning baffle 5 contacts the outer wall of the expansion section 302 and the reduction section 303 respectively. When the movable cleaning frame 4 moves, the annular cleaning baffle 5 alternately scrapes the outer wall of the expansion section 302 and the reduction section 303, and rotates under the push of the flue gas to play a baffle role.

[0034] Specifically, after being crushed in the first feeding workshop, the biomass bulk material is transported to the second feeding workshop and then conveyed by a conveyor belt to the gasifier transfer silo. The transfer silo is responsible for evenly distributing the biomass to the two gasifiers. After pyrolysis in the gasifier, the biomass produces biomass gas, which is drawn into the boiler burner by a gas induced draft fan and mixed with air supplied by the blower for combustion. The flue gas after combustion is discharged through the furnace to the tail flue. The tail flue is equipped with an energy-saving device and an air preheater. Inside the air preheater 2, a pair of heat exchange tube groups 3 are installed at intervals along the flue gas flow direction. Each heat exchange tube group 3 consists of multiple parallel heat exchange tube bundles 301. The heat exchange tube bundles 301 are used to supply cold air flow, and their tube walls serve as heat transfer surfaces for the high-temperature flue gas in the exhaust duct 101. To enhance heat transfer and optimize flow characteristics, the outer wall of the heat exchange tube bundle 301 is composed of alternating expansion sections 302 and contraction sections 303 along its axis. This alternating tube diameter design causes the cross-section of the flue gas flow path to change periodically, effectively disrupting the laminar boundary layer of the flue gas, enhancing turbulence, and improving heat exchange efficiency. Simultaneously, a spiral guide vane 304 is installed on the inner wall of the contraction section 303. When air flows through the contraction section 303, the spiral guide vane 304 guides the air to generate swirling flow, further enhancing the convective heat transfer coefficient within the tube. The movable cleaning frame 4 is movably installed within the housing of the air preheater 2 and can reciprocate along the distribution direction of the heat exchange tube group 3 under the drive of a driving component. The movable cleaning frame 4 has openings... The system includes through holes 401 corresponding to the number and position of the heat exchange tube bundles 301, allowing the movable cleaning frame 4 to be fitted onto the entire row of heat exchange tube bundles 301 and move along them. When the movable cleaning frame 4 moves left and right under the action of the drive mechanism, it drives all the annular cleaning baffles 5 to move together. Since the inner ring surface of the annular cleaning baffles 5 is always in contact with the outer wall of the heat exchange tube bundles 301, it continuously scrapes the tube wall during the movement. This mechanical scraping cleaning method is more direct and powerful than traditional steam soot blowing or sonic soot blowing, and can effectively remove various deposits, including highly adhesive ash, resulting in more thorough cleaning. This cleaning process can be completed automatically during normal boiler operation without shutdown, greatly ensuring the smooth operation of the equipment. The continuity and stability of thermal efficiency fundamentally solve the problems of decreased heat exchange efficiency and flow channel blockage caused by ash accumulation. During boiler operation, high-temperature flue gas continuously flows through the heat exchange tube bundle 301. The flue gas flow exerts a force on the annular cleaning and turbulence-inducing element 5, pushing it to rotate around the axis of the heat exchange tube bundle 301. The rotating annular cleaning and turbulence-inducing element 5 itself constitutes a highly efficient turbulent element. It not only cleans the tube wall but also continuously and dynamically turbulents the flue gas flowing around it, strongly disrupting the laminar boundary layer on the surface of the heat exchange tube wall and significantly enhancing the turbulence on the flue gas side. The enhanced turbulence directly leads to a significant increase in the convective heat transfer coefficient between the flue gas and the tube wall, thereby strengthening the heat transfer effect. The two processes of ash removal and turbulence-enhanced heat transfer are dynamically combined.This achieves heat exchange alongside dust removal, and synergistic dust removal during heat exchange.

[0035] Compared with existing technologies, this invention, through the provision of a movable cleaning frame 4 and multiple annular cleaning baffles 5 within it, continuously scrapes the outer wall of the heat exchange tube bundle 301 during its movement. This mechanical scraping method is more thorough than traditional soot blowing, especially effective at removing highly adhesive ash. This process can be performed automatically during boiler operation without shutdown, ensuring long-term, high-efficiency operation of the equipment and fundamentally solving the problems of efficiency reduction and blockage caused by ash accumulation. The annular cleaning baffles 5 rotate under the propulsion of flue gas and are themselves highly efficient baffles, not only cleaning the tube walls... While continuously disrupting the laminar boundary layer of the heat exchange tube wall, the turbulence on the flue gas side is enhanced, thereby significantly improving the heat transfer effect and achieving the synergistic effect of heat exchange during cleaning and heat exchange. The alternating arrangement of the expansion section 302 and the reduction section 303 of the heat exchange tube bundle 301 causes periodic changes in the velocity and direction of the flue gas and air, further enhancing turbulent heat transfer. The expansion section 302 provides expansion space for the flue gas, which helps to reduce the overall pressure loss, while the spiral guide vanes 304 of the reduction section 303 guide the air to rotate within the heat exchange tube bundle 301, further improving the heat transfer coefficient.

[0036] In a further embodiment of the present invention, a flue gas inlet 201 connected to the flue gas duct 101 is provided at the bottom of one side of the air preheater 2, and a flue gas outlet 202 is provided at the top of the air preheater 2. A pair of heat exchange tube groups 3 are distributed vertically inside the air preheater 2, and an air inlet 203 and an air outlet 204 respectively connected to the two heat exchange tube groups 3 are provided on the other side of the air preheater 2. A reversing air chamber 205 for connecting the two heat exchange tube groups 3 is provided inside the air preheater 2. Specifically, the pair of heat exchange tube groups 3 are installed vertically inside the air preheater 2. This arrangement is conducive to forming a more reasonable airflow channel and temperature distribution. High-temperature flue gas enters the bottom of the air preheater 2 from the flue gas inlet 201 through the flue gas duct 101 of the boiler body 1. The flue gas mainly flows upward inside the air preheater 2, first scouring the outer wall of the tube bundle of the lower heat exchange tube group 3, transferring some heat to the air inside the tube. Subsequently, the flue gas continues to rise, scouring the outer wall of the tube bundle of the upper heat exchange tube group 3. The second heat exchange occurs, further reducing the temperature. Finally, the cooled flue gas is discharged from the flue gas outlet 202 at the top of the air preheater 2, while the cold air enters from the air inlet 203, first entering the tubes of the upper heat exchange tube group 3. At this point, the airflow direction is opposite to the overall flue gas flow direction. This counter-current arrangement has the largest average heat transfer temperature difference and high heat exchange efficiency. The air is initially heated as it flows through the upper heat exchange tube group 3. After the first heating, the warm air flows out from the outlet of the upper heat exchange tube group 3 and enters the reversing air chamber 205. In the reversing air chamber 205, the air changes its flow direction and is guided to the inlet of the lower heat exchange tube group 3. The warm air enters the tubes of the lower heat exchange tube group 3 and continues to absorb heat from the flue gas. In this stage, after the second heating, the air reaches the predetermined temperature and becomes hot air. Finally, the hot air flows out from the outlet of the upper heat exchange tube group 3 and is sent out through the air outlet 204 to supply the boiler burner. This achieves two-stage preheating of the air and realizes the purpose of energy saving.

[0037] In a further embodiment of the present invention, tube sheets 305 are fixedly connected to both sides of the heat exchange tube bundle 3, and the two ends of the heat exchange tube bundle 301 are respectively fixed to the two tube sheets 305. A support frame 6 is fixedly connected inside the air preheater 2, and the tube sheets 305 are connected to the support frame 6. Specifically, tube holes are machined on the tube sheets 305 that precisely correspond to the number and position of the heat exchange tube bundles 301. The two ends of each heat exchange tube bundle 301 are respectively inserted into the tube holes of the two tube sheets 305 and fixed by welding or expansion joints. The tube sheets 305 on both sides and all the heat exchange tube bundles 301 together constitute a rigid, modular unit. The heat exchange module is connected and fixed to the support frame 6 by bolts. The weight and force of the entire heat exchange tube bundle 3 can be effectively transferred to the shell of the air preheater 2 through the support frame 6. This ensures that the spatial position of all heat exchange tube bundles 301 is relatively fixed, maintaining precise parallelism and spacing. This provides conditions for the smooth and interference-free reciprocating movement of the moving cleaning frame 4 and its annular cleaning baffle 5 along the entire heat exchange tube bundle 3. It effectively resists the vibration that may be induced by flue gas flow and avoids tube bundle fatigue damage or cracking at the connection of tube sheet 305 caused by long-term vibration.

[0038] In a further embodiment of the present invention, a dual-axis motor 402 is fixedly connected between the two movable cleaning frames 4. A transmission rod 403 is installed at both ends of the dual-axis motor 402, and a drive gear 404 is fixedly connected to the end of each transmission rod 403. A rack 601, meshing with the bottom of the drive gear 404, is fixedly connected to both sides of the inner wall of the support frame 6. Specifically, when dust removal is required, the dual-axis motor 402 is started. The dual-axis motor 402 synchronously drives the two drive gears 404 to rotate via the transmission rods 403 at both ends. Since the drive gear 404 meshes with the rack 601 fixed to the support frame 6, the rotational motion of the gears is converted into linear motion of the entire motor and the connected movable cleaning frame 4 assembly along the length of the rack 601. The dual-motor shaft output design ensures absolute synchronization of the two-sided drive, avoiding the twisting or jamming that may occur with single-point drive, and ensuring that the upper and lower movable cleaning frames 4 can move together in parallel and smoothly. This ensures that the scraping force of all annular cleaning baffles 5 on the heat exchange tube bundle 301 is uniform and consistent. The rigid transmission method features high transmission efficiency, strong load-bearing capacity, and no slippage. It can provide sufficient power to overcome the frictional resistance between the annular cleaning turbulence member 5 and the outer wall of the heat exchange tube bundle 301, ensuring the effective execution of the dust removal action. At the same time, the structure itself has good guidance and position retention. The movement trajectory of the moving cleaning frame 4 is strictly limited and will not wobble. By controlling the direction and speed of the dual-axis motor 402, the moving direction and speed of the moving cleaning frame 4 can be easily controlled. The movement stroke of the cleaning frame can also be precisely controlled by a program or limit switch to ensure that it can perform full-coverage cleaning within the effective length of the heat exchange tube bundle 3. This drive mechanism cleverly utilizes the existing support frame 6 in the previous embodiment as the installation base and fixes the rack 601 on it. There is no need to add an additional complex support structure in the preheater shell, making the design compact. The support frame 6 itself has high rigidity, providing a stable reference surface for the rack 601, further ensuring the smoothness and accuracy of the transmission.

[0039] In a further embodiment of the present invention, the annular cleaning baffle 5 includes a cleaning sleeve 501 rotatably connected to both sides of the inner wall of the movable cleaning frame 4. It is rotatably connected to the inner wall of the through hole 401 of the movable cleaning frame 4 via bearings (not shown in the figure). A plurality of blades 502 are annularly distributed on the outer wall of the cleaning sleeve 501. An elastic scraper 503 is movably inserted into the inner wall of the cleaning sleeve 501. A top spring is installed between the insertion end of the elastic scraper and the cleaning sleeve. Both sides of the elastic scraper 503 are provided with abutting parts that engage with the reduced diameter portion 303. Specifically, when flue gas flows through the heat exchange tube bundle 301, it impacts the blades 502 on the outer wall of the cleaning sleeve 501. The force of the flue gas drives the entire annular cleaning baffle 5 to rotate continuously. The rotating blades 502 and the cleaning sleeve 501 themselves are a highly efficient baffle unit. They continuously and violently agitate the flue gas, disrupting the laminar boundary layer of the tube wall and greatly enhancing the heat transfer process. When the moving cleaning frame 4 drives the annular cleaning baffle 5 to move along the heat exchange tube bundle 301, the cleaning sleeve 501... Dust is removed from the surface of the expanded diameter section 302 in the heat exchange tube bundle 301. When the cleaning sleeve 501 reaches the reduced diameter section 303, the elastic scraper 503 extends under the action of elasticity to clean the recessed area. When the moving cleaning frame 4 moves the elastic scraper 503 from the reduced diameter section 303 to the expanded diameter section 302, under the guiding and squeezing action of the conical surface between the expanded diameter section 302 and the reduced diameter section 303, the inclined surface of the inclined groove 504 is forced to slide along the tube wall, converting the axial movement trend into the movement of the elastic scraper 503. The radial pressure forces the elastic scraper 503 to retract into the cleaning sleeve 501, working together with the cleaning sleeve 501 to clean the dust in the expanded diameter section 302. The entire scraping process can be completed as the elastic scraper 503 rotates continuously with the cleaning sleeve 501. This means that the elastic scraper 503 does not just perform axial linear scraping, but forms a spiral forward motion trajectory. This composite motion can perform all-round, no-dead-angle scraping and dust removal on the outer wall of the heat exchange tube bundle 301 more thoroughly.

[0040] In a further embodiment of the present invention, a plurality of ash discharge holes 505 are annularly distributed on the cleaning sleeve 501. The ash discharge holes 505 are staggered from the blades 502. Specifically, when the cleaning sleeve 501 rotates at high speed under the impetus of flue gas, the dust scraped off by the elastic scraper 503 inside it is thrown towards the inner wall of the cleaning sleeve 501 due to centrifugal force. Due to the presence of the ash discharge holes 505, the dust accumulated on the inner wall is directly thrown out from the ash discharge holes 505 under the continuous action of centrifugal force and discharged into the main flue gas flow. Without the ash discharge holes 505, the dust would be... The dust removed by the elastic scraper 503 will accumulate in the annular gap between the cleaning sleeve 501 and the outer wall of the heat exchange tube bundle 301. Over time, this will not only hinder the rotation of the annular cleaning turbulence element 5, but may even block the gap in severe cases. The staggered arrangement of the blades 502 and the ash discharge hole 505 makes the functional zoning of the outer wall of the cleaning sleeve 501 clear. The blade 502 area is mainly responsible for driving the rotation, while the ash discharge hole 505 area is responsible for ash discharge. This helps to form a relatively orderly flow field locally, reduce the eddies that may be caused by the intersection of the opening and the blades 502, and reduce unnecessary flow resistance.

[0041] In a further embodiment of the present invention, pull rods 7 are vertically slidably installed on both sides of the inner walls of the two movable cleaning frames 4. Several abutments 701 are vertically distributed on the pull rods 7. Several receiving grooves 405 are provided on the side walls of the movable cleaning frames 4 to abut against each abutment 701. A plug-in post 702 is fixedly connected to the middle of the pull rod 7. Corrugated guide grooves 602 are horizontally provided on both sides of the support frame 6 for inserting the plug-in post 702. Specifically, the pull rods 7 can slide slightly in the vertical direction relative to the movable cleaning frames 4. The corrugated guide grooves 602 are wave-shaped with continuous peaks and troughs. When the movable cleaning frames 4 are driven by the dual-axis motor 402... When moving horizontally, the plug 702, fixedly connected to the middle of the pull rod 7, is forced to slide along the corrugated guide groove 602 on the stationary support frame 6. Since the corrugated guide groove 602 undulates horizontally, when the plug 702 slides from the trough to the crest or vice versa, the groove wall forces the plug 702 to move vertically. This horizontal movement is transmitted to the pull rod 7 through the plug 702, causing the pull rod 7 to produce vertical reciprocating micro-movements relative to the moving cleaning frame 4. During the vertical micro-movement, the abutment 701 on the pull rod 7 periodically impacts the groove wall of the receiving groove 405 on the side wall of the moving cleaning frame 4. This continuous, high-frequency impact... This generates stable high-frequency vibrations, which are transmitted through the moving cleaning frame 4 to all the annular cleaning baffles 5, ultimately acting on the elastic scraper 503. This causes the elastic scraper 503 to perform a high-frequency micro-vibration or shaking while simultaneously performing rotational scraping. This composite cleaning method of rotational scraping combined with high-frequency vibration effectively breaks up and loosens the hard ash shell, greatly reducing the adhesion between the ash and the pipe wall, allowing the elastic scraper 503 to easily remove it. This mechanism is particularly suitable for treating sticky ash produced by oil-fired boilers and biomass boilers. The shaking function is entirely derived from the main motion of the moving cleaning frame 4. Without the need for an additional power source or control system, it achieves efficient energy utilization and simplification of the mechanism. The vibration frequency is proportional to the moving speed of the moving cleaning frame 4. The faster the speed, the higher the vibration frequency. Users can optimize the dust removal effect by adjusting the motor speed. This vibration mechanism works seamlessly with all previous functions. The annular cleaning baffle 5 continues to rotate freely under the propulsion of flue gas, and the ash discharge hole 505 continues to discharge ash by centrifugal force. Horizontal vibration not only does not affect these functions, but also forms a multi-dimensional dust removal force through superposition with the rotating scraper. It can also quickly shake off the dust adhering to the heat exchange tube group 3 and the annular cleaning baffle 5 itself.

[0042] In a further embodiment of the present invention, a guide plate 603 is fixedly connected to one side of the support frame 6 inside the reversing air chamber 205. An impeller 8 and a baffle 9 are rotatably installed inside the reversing air chamber 205 below the guide plate 603. An eccentric shaft 801 is installed at both ends of the impeller 8, and a connecting rod 901 hinged to the eccentric shaft 801 is installed at both ends of the baffle 9. Specifically, after the air flowing out from the lower heat exchange tube group 3 enters the reversing air chamber 205, it first impacts the guide plate 603. The guide vane 603 provides a smooth transition surface, effectively guiding the airflow to smoothly change direction and flow towards the inlet of the heat exchange tube group 3 located below. This avoids the air directly impacting the flat chamber wall, which would generate violent eddies and large local pressure losses, achieving preliminary optimization of the airflow direction and reducing fan energy consumption. The airflow after passing through the guide vane 603 has a certain kinetic energy. This part of the airflow impacts and drives the impeller 8 to rotate. The rotational energy of the impeller 8 comes entirely from the recovered air kinetic energy, requiring no additional power source, thus achieving energy saving. When the impeller 8 rotates, the eccentric shafts 801 at both ends of it also perform circular motion. Through the connection of the connecting rod 901, the circular motion of the eccentric shafts 801 is converted into the reciprocating oscillating motion of the baffle 9. The oscillation amplitude and frequency are determined by the rotational speed of the impeller 8. The internal space of the reversing wind chamber 205 is relatively large, making it easy to form a stable, large-scale recirculation vortex zone. Eddies not only increase pressure loss but can also lead to air stagnation and uneven mixing. Traditional fixed guide vanes have limited effectiveness in addressing this issue. However, in this embodiment, the periodic reciprocating oscillation of the baffle 9 can actively and continuously break these large-scale eddies, cutting them into small-scale, easily dissipated turbulence. This results in more uniform air mixing and smoother flow, further reducing flow resistance. After being disturbed by the impeller 8 and the baffle 9, the turbulence of the air increases significantly. This fully disturbed air with higher turbulence enters the tubes of the lower heat exchanger tube group 3, which can more effectively disrupt the air boundary layer inside the tubes, thereby enhancing the heat exchange effect on the inner side of the upper heat exchanger tube group 3. This makes the secondary preheating effect more significant. Under high load, the airflow is large, the impeller 8 rotates quickly, and the baffle 9 oscillates violently, resulting in a strong turbulence effect. Under low load, the movement is gentle. This adaptability ensures that appropriate guiding and turbulence effects can be obtained under various operating conditions.

[0043] In a further embodiment of the present invention, an ash hopper 10 is provided at the bottom of the air preheater 2, and a dust filter 11 is installed at the top of the ash hopper 10. Ash discharge troughs 12 are provided on both sides of the dust filter 11. The bottom of a movable cleaning frame 4 abuts against the dust filter 11, and a dust removal brush 406 is embedded in the side wall of the movable cleaning frame 4. Specifically, the flue gas comes from the boiler and enters the bottom of the air preheater 2 tangentially through the flue gas inlet 201 located on the side of the ash hopper 10 area. All the flue gas entering from the flue gas inlet 201 must first pass through the dust filter 11 from bottom to top before reaching the heat exchange tube group 3. The dust filter 11 will remove most of the large dust particles carried in the flue gas. After interception and pretreatment, the dust concentration in the flue gas entering the heat exchange tube bundle 3 is significantly reduced, thereby fundamentally reducing the main dust removal load of the annular cleaning turbulence component 5 on the heat exchange tube bundle 301, greatly extending its maintenance cycle and service life. The movable cleaning frame 4 and its dust removal brush 406 are located above the filter screen. When the movable cleaning frame 4 moves, the dust removal brush 406 will brush the upper surface of the filter screen, which can push the dust blocking the mesh downwards, while avoiding pushing large dust particles to the clean side. The high-frequency vibration generated by the movable cleaning frame 4 will also be transmitted to the flue gas filter screen 11, forming a powerful vibration effect, which can effectively shake off the dust clumps adhering to the lower surface of the filter screen.

[0044] In a further embodiment of the present invention, a heat-conducting metal wire 306 is embedded between the spiral guide vane 304 and the heat exchange tube bundle 301. After the heat-conducting metal wire 306 is embedded, heat is efficiently transferred to the spiral guide vane 304, causing its temperature to rise significantly. This transforms the spiral guide vane 304 from a simple flow guiding component into a highly efficient extended heat exchange fin. At this time, the spiral guide vane 304 not only guides the air to rotate, but also directly and actively participates in the heat exchange with the cold air, greatly increasing the effective heat transfer area.

[0045] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An energy-saving boiler, comprising a boiler body (1) and a flue gas duct (101) installed on the boiler body (1), characterized in that, Also includes: An air preheater (2) is installed at the end of the flue gas duct (101). The air preheater (2) is equipped with a pair of heat exchange tube groups (3) distributed along the flue gas emission direction. The heat exchange tube group (3) is composed of multiple heat exchange tube bundles (301). The heat exchange tube bundles (301) are provided with an expansion section (302) and a contraction section (303) that are alternately distributed along their axis. The inner wall of the contraction section (303) is provided with a spiral guide vane (304). A movable cleaning frame (4) with openings at the top and bottom is movably installed in the heat exchange tube bundle (3) and has through holes (401) for the heat exchange tube bundle (301) to pass through. Inside the movable cleaning frame (4), there is an annular cleaning baffle (5) corresponding to each heat exchange tube bundle (301). The annular cleaning baffle (5) contacts the outer wall of the expansion section (302) and the contraction section (303) respectively. When the moving cleaning frame (4) moves, the annular cleaning baffle (5) alternately scrapes the outer walls of the expanded diameter section (302) and the narrowed diameter section (303), and rotates under the push of the flue gas to play a baffle role.

2. The energy-saving boiler according to claim 1, characterized in that, The air preheater (2) has a flue gas inlet (201) at the bottom of one side connected to the flue gas duct (101), a flue gas outlet (202) at the top of the air preheater (2), a pair of heat exchange tube groups (3) distributed vertically inside the air preheater (2), and an air inlet (203) and an air outlet (204) connected to the two heat exchange tube groups (3) respectively on the other side of the air preheater (2). The air preheater (2) has a reversing air chamber (205) for connecting the two heat exchange tube groups (3).

3. An energy-saving boiler according to claim 1, characterized in that, The heat exchange tube bundle (3) is fixedly connected to tube sheets (305) on both sides. The two ends of the heat exchange tube bundle (301) are fixed to the two tube sheets (305) respectively. The air preheater (2) is fixedly connected to a support frame (6). The tube sheet (305) is connected to the support frame (6).

4. An energy-saving boiler according to claim 3, characterized in that, A dual-axis motor (402) is fixedly connected between the two movable cleaning frames (4). A transmission rod (403) is installed at both ends of the dual-axis motor (402). A drive gear (404) is fixedly connected to the end of the transmission rod (403). A rack (601) that meshes with the bottom of the drive gear (404) is fixedly connected to both sides of the inner wall of the support frame (6).

5. An energy-saving boiler according to claim 1, characterized in that, The annular cleaning baffle (5) includes a cleaning sleeve (501) that is rotatably connected to both sides of the inner wall of the movable cleaning frame (4). Several blades (502) are distributed in annularly on the outer wall of the cleaning sleeve (501). An elastic scraper (503) is movably inserted into the inner wall of the cleaning sleeve (501). Both sides of the elastic scraper (503) are provided with abutting grooves (504) that abut against the reduced diameter part (303).

6. An energy-saving boiler according to claim 5, characterized in that, The cleaning sleeve (501) has a number of ash discharge holes (505) distributed in a ring, and the ash discharge holes (505) are staggered from the blades (502).

7. An energy-saving boiler according to claim 3, characterized in that, Both sides of the inner wall of the two movable cleaning frames (4) are vertically slidably equipped with pull rods (7), and several abutments (701) are vertically distributed on the pull rods (7). Several receiving grooves (405) are opened on the side wall of the movable cleaning frame (4) to abut and cooperate with each abutment (701). A plug-in post (702) is fixedly connected in the middle of the pull rod (7). Both sides of the support frame (6) are horizontally provided with wavy guide grooves (602) for the plug-in post (702) to be inserted.

8. An energy-saving boiler according to claim 3, characterized in that, A guide plate (603) is fixedly connected to one side of the support frame (6) inside the reversing chamber (205). An impeller (8) and a baffle plate (9) are rotatably installed inside the reversing chamber (205) below the guide plate (603). An eccentric shaft (801) is installed at both ends of the impeller (8), and a connecting rod (901) is hinged to the eccentric shaft (801) at both ends of the baffle plate (9).

9. An energy-saving boiler according to claim 1, characterized in that, The air preheater (2) is provided with a dust hopper (10) at the bottom, and a dust filter screen (11) is installed on the top of the dust hopper (10). Dust discharge troughs (12) are provided on both sides of the dust filter screen (11). The bottom of one of the movable cleaning frames (4) abuts against the dust filter screen (11), and a dust removal brush (406) is embedded in the side wall of the movable cleaning frame (4).

10. An energy-saving boiler according to claim 1, characterized in that, A heat-conducting metal wire (306) is embedded between the spiral guide vane (304) and the heat exchange tube bundle (301).

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