Ash removal system for recirculation flue of tower type boiler

Abstract

The invention discloses a tower type boiler recirculation flue ash removal system, and relates to the technical field of thermal power generation boiler equipment. The problems of ash blockage and serious abrasion of fan blades caused by excessive ash amount of an existing tower-type boiler recirculation flue system are solved. The system comprises a rough filtration unit and a fine filtration unit which are connected in series along the flue gas flow. The rough filtration unit is arranged at a recycling smoke taking opening of the vertical main flue and comprises a flaring type smoke taking cover and an ash baffle obliquely arranged in the flaring type smoke taking cover. The fine filtration unit is arranged at the inlet section of the recirculation fan at the downstream of the rough filtration unit and comprises a settling flue section, an ash bucket arranged at the bottom of the settling flue section, a guide plate arranged above the ash bucket and a labyrinth baffle positioned behind an outlet of the ash bucket. By means of the two-stage ash removal structure, the amount of ash entering the draught fan is remarkably reduced, the risks of impeller abrasion and flue blockage are effectively reduced, and the safety and economical efficiency of boiler operation are improved.

Description

Technical Field

[0001] This invention relates to the field of thermal power boiler equipment technology, specifically to an ash removal system for a tower boiler recirculation flue. Background Technology

[0002] Tower boilers, especially double reheat tower boilers, are increasingly widely used in thermal power generation due to their high efficiency and energy saving advantages. The recirculated flue gas system is a key component of this type of boiler; its function is to draw a portion of the flue gas from the tail flue and return it to the furnace to regulate the steam temperature.

[0003] In existing technologies, the recirculation system of tower boilers typically draws flue gas from a high, vertical flue area. Because the flue runs vertically downwards, and the flue gas in this area carries a high concentration and wide range of fly ash particles, the amount of ash in the recirculation flue is excessive. This leads to two prominent problems: First, large ash particles easily deposit in the flue, causing blockages and affecting the normal operation of the system; second, high-speed flue gas carrying hard ash particles directly enters the recirculation fan, causing severe erosion and wear on the fan blades. This not only shortens the fan's service life and increases maintenance costs, but also may lead to unplanned shutdowns of the entire boiler unit due to fan failure, seriously affecting the safety and economy of power plant operation.

[0004] Current technologies lack effective pre-treatment ash removal measures specifically for the high-position, vertically downward flue gas extraction characteristics of tower boilers. Conventional ash removal devices often fail to effectively separate large ash particles within a limited space, resulting in the persistent problems of ash blockage and wear, which have become a bottleneck restricting the further promotion and application of double reheat tower boiler technology.

[0005] Therefore, there is an urgent need for an ash removal solution specifically designed for the recirculation flue system of tower boilers, which can effectively separate and remove large particles of fly ash before the flue gas enters the fan, in order to solve the long-standing technical problem of flue blockage and fan wear. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of excessive ash accumulation leading to ash blockage and severe wear of fan blades in existing tower boiler recirculation flue systems, and to provide a tower boiler recirculation flue ash removal system.

[0007] The technical solution of this invention is:

[0008] This invention provides an ash removal system for a tower boiler recirculation flue. The system is connected between the vertical main flue of the tower boiler and the recirculation fan. The system includes a coarse filtration unit 1 and a fine filtration unit 2. The coarse filtration unit 1 is located at the recirculation flue intake of the vertical main flue. The coarse filtration unit 1 includes a flared flue hood 11 and a first ash baffle 12 inclinedly disposed on the downstream side inside the flared flue hood 11. The fine filtration unit 2 is located downstream of the coarse filtration unit 1. The fine filtration unit 2 includes a settling flue section 21, at least one ash hopper 22 disposed at the bottom of the settling flue section 21, a guide plate 23 disposed inside the settling flue section 21 and above the ash hopper 22, and a labyrinthine baffle 24 disposed inside the settling flue section 21 and behind the outlet of the ash hopper 22.

[0009] Furthermore, the outlet cross-sectional area of ​​the flared smoke hood 11 is 1.5 to 2 times the inlet cross-sectional area of ​​the flared smoke hood 11.

[0010] Furthermore, the flared smoke hood 11 is used to reduce the internal smoke flow rate to 8~10m / s.

[0011] Furthermore, there are multiple first dust baffles 12, which are arranged parallel to each other and spaced apart along the width direction of the flared smoke hood 11. The first dust baffles 12 have a V-shaped plate structure and are used to bounce large dust particles that impact the surface back into the vertical main flue.

[0012] Furthermore, the settling flue section 21 has a flared structure (25) in the section corresponding to the ash hopper 22.

[0013] Furthermore, the diffusion angle of the flared structure (25) is 60°.

[0014] Furthermore, there are multiple guide plates 23, which are arranged alternately in the settling flue section 21. Each guide plate 23 has a straight plate structure and is used to change the direction of flue gas flow and guide ash particles to settle into the ash hopper 22.

[0015] Furthermore, the labyrinthine baffle 24 is composed of multiple baffles, and narrow channels are formed between the baffles to allow the flue gas to pass through in a detour.

[0016] Furthermore, there are four ash hoppers 22, which are arranged sequentially along the bottom of the settling flue section 21.

[0017] Furthermore, the fine filtration unit 2 also includes a second baffle plate 26, which has a V-shaped plate structure. The second baffle plate 26 is disposed inside the settling flue section 21 and located behind the outlet of the ash hopper 22. The second baffle plate 26 is located in front of the labyrinth baffle 24. There are multiple second baffle plates 26, which are arranged parallel and spaced apart along the width of the flue.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. This invention proposes a two-stage synergistic ash removal architecture combining coarse and fine filtration. This architecture is a customized solution for the specific operating conditions of high-position flue gas intake and vertical downward flow in tower boiler recirculation systems. The coarse filter unit 1 is not a simple filter screen, but rather achieves structural velocity reduction through a flared flue gas hood 11, creating the necessary conditions for the subsequent first baffle plate 12 to rebound large ash particles using the inertial separation principle. This organic combination of flared velocity reduction and inertial rebound achieves in-situ separation of most large ash particles at the flue gas intake, allowing them to return directly to the main flue and be carried away by the mainstream flue gas, rather than entering the recirculation system. This fundamentally reduces the processing load and ash blockage risk of subsequent systems, which cannot be achieved by simply adding a filter screen to the pipeline.

[0020] 2. The fine filtration unit 2 of this invention is a composite ash removal structure that comprehensively utilizes multiple physical principles. Firstly, it achieves secondary expansion and deceleration through the flared structure (25) of the settling flue section 21, using gravity settling to allow some ash particles to fall into the ash hopper 22. Then, the guide plate 23 actively disturbs and guides the flue gas flow, enhancing the inertial separation effect. Finally, the labyrinthine baffle 24 forms a meandering channel for efficient collection of residual particles. The three mechanisms of gravity settling, inertial separation, and labyrinthine flow are not simply stacked in the fine filtration unit 2, but rather form a functional connection and complementarity, ensuring deep purification of flue gas under any operating condition, thereby providing unprecedented protection for the recirculation fan and greatly reducing the risk of wear.

[0021] 3. This invention achieves systematic optimization by reducing the burden on the front end and ensuring the quality of the back end through the synergistic effect of the coarse filtration unit 1 and the fine filtration unit 2. The coarse filtration unit 1 removes most of the large, impactful particles, allowing the fine filtration unit 2 to focus on processing finer particles. This not only improves the overall ash removal efficiency but also extends the service life of the fine filtration unit 2. This systematic design approach successfully solves the long-standing problems of ash blockage and fan wear in reheat tower boilers. Its technical effectiveness has been verified in the renovation project of Fengcheng Power Plant, and it is of great significance for improving the reliability and economy of unit operation. Attached Figure Description

[0022] Figure 1This is a schematic diagram of the coarse filter unit in the ash removal system of the recirculating flue gas duct of the tower boiler of the present invention;

[0023] Figure 2 This is a schematic diagram of the fine filtration unit in the ash removal system of the recirculating flue gas duct of the tower boiler of the present invention.

[0024] In the diagram: 1-coarse filter unit; 11-flared smoke hood; 12-first baffle plate; 21-settling flue section; 2-fine filter unit; 22-ash hopper; 23-guide plate; 24-labyrinth baffle; 25-flared structure; 26-second baffle plate. Detailed Implementation

[0025] Specific implementation method one: Combining Figure 1 and Figure 2 This embodiment describes an ash removal system for a tower boiler recirculation flue. The system is connected between the vertical main flue of the tower boiler and the recirculation fan. The system includes a coarse filtration unit 1 and a fine filtration unit 2. The coarse filtration unit 1 is located at the recirculation flue intake of the vertical main flue. The coarse filtration unit 1 includes a flared flue hood 11 and a first ash baffle 12 inclinedly disposed on the downstream side inside the flared flue hood 11. The fine filtration unit 2 is located downstream of the coarse filtration unit 1. The fine filtration unit 2 includes a settling flue section 21, at least one ash hopper 22 disposed at the bottom of the settling flue section 21, a guide plate 23 disposed inside the settling flue section 21 and above the ash hopper 22, and a labyrinthine baffle 24 disposed inside the settling flue section 21 and behind the outlet of the ash hopper 22.

[0026] Specific Implementation Method Two: Combining Figure 1 and Figure 2 In this embodiment, the outlet cross-sectional area of ​​the flared smoke hood 11 is 1.5 to 2 times the inlet cross-sectional area. This setting, limiting the flare ratio to the proven range of 1.5 to 2 times, effectively reduces the smoke velocity from the mainstream high speed to the ideal range of 8 to 10 m / s within a limited installation space. This velocity range ensures that large dust particles, due to inertia, are sufficiently separated from the airflow to impact the first baffle plate 12, while avoiding structural bulk and increased cost due to excessive flare, achieving the best balance between technical effectiveness and economy. Other components and connections are the same as in Specific Embodiment One.

[0027] Specific implementation method three: Combining Figure 1 and Figure 2This embodiment describes a flared smoke hood 11 used to reduce the internal flue gas velocity to 8-10 m / s. This design clearly defines the effect of velocity reduction, ensuring that large ash particles have sufficient residence time within the flared smoke hood 11 for effective separation by the first baffle plate 12. Other components and connections are the same as in specific embodiments one or two.

[0028] Specific implementation method four: Combination Figure 1 and Figure 2 In this embodiment, there are multiple first ash baffles 12. These multiple first ash baffles 12 are arranged parallel to each other and spaced apart along the width direction of the flared smoke hood 11. The first ash baffles 12 have a V-shaped plate structure and are used to bounce large ash particles impacting the surface back into the vertical main flue. This arrangement clarifies that the core function of the first ash baffles 12 is to achieve inertial separation, directly guiding large ash particles back into the main flue and preventing them from entering subsequent systems. Other components and connections are the same as in specific embodiments one, two, or three.

[0029] Specific Implementation Method Five: Combining Figure 1 and Figure 2 In this embodiment, the settling flue section 21 has a flared structure (25) in the section corresponding to the ash hopper 22. This configuration creates a low-velocity zone in the fine filtration unit 2, which facilitates the natural settling of ash particles into the ash hopper 22 under gravity. Other components and connections are the same as in specific embodiments one, two, three, or four.

[0030] Specific Implementation Method Six: Combination Figure 1 and Figure 2 In this embodiment, the diffusion angle of the flared structure (25) is 60°. This 60° diffusion angle is the preferred angle determined through fluid dynamics calculations and experimental verification. This angle can form a stable and effective low-pressure vortex zone in the flue, which is most conducive to the gravity settling of ash particles, while ensuring a smooth airflow transition. This avoids the problems of flow separation caused by an excessively large angle or insufficient settling space caused by an excessively small angle, thereby maximizing the ash collection efficiency of the ash hopper 22. Other components and connections are the same as in specific embodiments one, two, three, four, or five.

[0031] Specific implementation method seven: Combination Figure 1 and Figure 2In this embodiment, there are multiple guide plates 23 arranged alternately within the settling flue section 21. Each guide plate 23 has a linear, plate-like structure and is used to change the direction of flue gas flow and guide ash particles to settle into the ash hopper 22. This arrangement allows the guide plates 23 to actively intervene in the flue gas flow field, enhancing the gas-solid separation process and improving the ash collection efficiency of the ash hopper 22. Other components and connections are the same as in specific embodiments one, two, three, four, five, or six.

[0032] Specific implementation method eight: Combination Figure 1 and Figure 2 This embodiment describes a labyrinthine baffle 24 composed of multiple baffles, with narrow channels between them allowing flue gas to pass through in a detour. This arrangement, through its specific baffle configuration, creates a non-straight-through flow path, forcing the flue gas and its carried ash particles to undergo multiple, rapid turns. Because the ash particles have much greater inertia than the flue gas, they cannot keep up with the airflow changes and thus continuously impact the baffle surface and are captured. This separation mechanism based on inertial effects is particularly effective in removing finer particles with a certain momentum that fail to settle at the front end, serving as a last line of defense for the fan. Other components and connections are the same as in specific embodiments one, two, three, four, five, six, or seven.

[0033] Specific Implementation Method Nine: Combining Figure 1 and Figure 2 In this embodiment, there are four ash hoppers 22, arranged sequentially along the bottom of the settling flue section 21. This arrangement increases the ash collection capacity and efficiency, meeting the ash removal requirements of longer flues. Other components and connections are the same as in specific embodiments one, two, three, four, five, six, seven, or eight.

[0034] Specific Implementation Method Ten: Combining Figure 1 and Figure 2In this embodiment, the fine filtration unit 2 further includes a second baffle plate 26. The second baffle plate 26 has a V-shaped plate structure and is located inside the settling flue section 21, behind the outlet of the ash hopper 22, and in front of the labyrinth-type baffle 24. Multiple second baffle plates 26 are arranged parallel and spaced apart along the width of the flue. This arrangement, with the second baffle plate 26 positioned behind the outlet of the ash hopper 22 and in front of the labyrinth-type baffle 24 in the fine filtration unit 2, forms a crucial pre-interception barrier. This component, through the principle of inertial separation, specifically captures medium-sized and larger particles remaining after the pre-treatment, effectively preventing large particles from impacting and clogging the precise labyrinth-type baffle 24, ensuring its long-term efficient operation. The second dust baffle 26 adopts a V-shaped structure combined with a layout of multiple parallel and spaced sections. The V-shaped design helps to stabilize particles and prevent secondary dust generation, while the parallel arrangement achieves complete coverage of the flue section without dead angles. Other components and connections are the same as in specific embodiments one, two, three, four, five, six, seven, eight, or nine.

[0035] Working principle

[0036] Combination Figure 1 and Figure 2 The working principle of the ash removal system for a tower boiler recirculation flue according to the present invention is as follows:

[0037] Flue gas enters the coarse filter unit 1 from the vertical main flue through the intake port. Inside the flared intake hood 11, the flue gas velocity is significantly reduced, and some large ash particles, under inertia, collide with the inclined first baffle plate 12 and are bounced back into the main flue, completing the primary ash removal. The pre-purified flue gas enters the settling flue section 21 of the fine filter unit 2. In the flared area above the ash hopper 22, the flue gas velocity is further reduced, and the flow direction is changed under the guidance of the guide plate 23, causing more ash particles to be captured in the ash hopper 22 due to gravity settling. Subsequently, the flue gas passes through the second baffle plate 26, whose V-shaped structure and parallel arrangement effectively pre-intercept medium-sized particles due to inertia. Finally, the flue gas passes through the labyrinthine baffle 24, whose winding narrow channels allow residual ash particles to be captured by inertial impact on the baffle surface. After these two stages of filtration, the clean flue gas finally enters the recirculation fan, thus fundamentally solving the problems of fan wear and flue blockage.

[0038] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ash removal system for a tower boiler recirculation flue, the system being connected between the vertical main flue of the tower boiler and a recirculation fan, characterized in that, The system includes a coarse filtration unit (1) and a fine filtration unit (2); the coarse filtration unit (1) is located at the recirculation smoke intake port of the vertical main flue, and the coarse filtration unit (1) includes a flared smoke intake hood (11) and a first baffle plate (12) inclinedly arranged on the downstream side inside the flared smoke intake hood (11); the fine filtration unit (2) is located downstream of the coarse filtration unit (1), and the fine filtration unit (2) includes a settling flue section (21), at least one ash hopper (22) arranged at the bottom of the settling flue section (21), a guide plate (23) arranged inside the settling flue section (21) and above the ash hopper (22), and a labyrinth baffle (24) arranged inside the settling flue section (21) and behind the outlet of the ash hopper (22).

2. The ash removal system for a tower boiler recirculating flue gas duct according to claim 1, characterized in that, The outlet cross-sectional area of ​​the flared smoke hood (11) is 1.5 to 2 times the inlet cross-sectional area of ​​the flared smoke hood (11).

3. The ash removal system for a tower boiler recirculating flue gas duct according to claim 1 or 2, characterized in that, The flared smoke hood (11) is used to reduce the internal smoke flow rate to 8~10m / s.

4. The ash removal system for a tower boiler recirculating flue gas duct according to claim 1, characterized in that, There are multiple first dust baffles (12), and the multiple first dust baffles (12) are arranged parallel to each other and spaced apart along the width direction of the flared smoke hood (11). The first dust baffles (12) have a V-shaped plate structure and are used to bounce large dust particles that impact the surface back to the vertical main flue.

5. The ash removal system for a tower boiler recirculating flue gas duct according to claim 1, characterized in that, The settling flue section (21) has a flared structure (25) in the section above the ash hopper (22).

6. The ash removal system for a tower boiler recirculating flue gas duct according to claim 5, characterized in that, The diffusion angle of the flared structure (25) is 60°.

7. The ash removal system for a tower boiler recirculating flue gas duct according to claim 1, characterized in that, The number of the guide plates (23) is multiple, and the multiple guide plates (23) are arranged alternately in the settling flue section (21). The guide plates (23) are in the form of a straight plate. The guide plates (23) are used to change the direction of flue gas flow and guide the ash particles to settle into the ash hopper (22).

8. The ash removal system for a tower boiler recirculating flue gas duct according to claim 1, characterized in that, The labyrinthine baffle (24) is composed of multiple baffles, and narrow channels are formed between the baffles to allow the flue gas to pass through in a detour.

9. The ash removal system for a tower boiler recirculating flue gas duct according to claim 1, characterized in that, There are four ash hoppers (22), which are arranged sequentially along the bottom of the settling flue section (21).

10. The ash removal system for a tower boiler recirculating flue gas duct according to claim 1, characterized in that, The fine filtration unit (2) also includes a second baffle plate (26). The second baffle plate (26) has a V-shaped plate structure. The second baffle plate (26) is located inside the settling flue section (21) and behind the outlet of the ash hopper (22). The second baffle plate (26) is located in front of the labyrinth baffle (24). There are multiple second baffle plates (26). The multiple second baffle plates (26) are arranged parallel and spaced apart along the width direction of the flue.

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