A coal-fired boiler manhole door structure

Abstract

The utility model discloses a coal powder boiler manhole door structure of the technical field of coal powder boiler equipment, which aims at solving the leakage problem caused by the fact that the existing manhole door cannot adapt to pressure fluctuation and aging of sealing material due to static sealing. The structure comprises a round well type door frame, a circular door cover hinged thereto and a locking mechanism. The door cover is provided with an annular sealing groove on one side. A sealing mechanism composed of a sealing ring gasket, a movable plate one, a movable plate two and a butterfly spring group between the two is arranged in the groove. Two ends of a U-shaped conduit are respectively connected with the inside of the boiler and the rear end of the sealing groove. When the pressure inside the boiler rises, the pressure is conducted to the rear end of the sealing groove through the U-shaped conduit, which pushes the movable plate one to compress the sealing ring gasket, forming a dynamic self-tight sealing. At the same time, the butterfly spring group can automatically compensate for the deformation of the sealing ring gasket caused by aging and creep, maintaining the sealing compression force. The utility model realizes reliable sealing throughout the whole cycle from cold state to hot state, significantly improving the sealing reliability and service life.

Description

Technical Field

[0001] This utility model relates to the technical field of pulverized coal boiler equipment, specifically a manhole door structure for a pulverized coal boiler. Background Technology

[0002] Manhole doors in pulverized coal boilers are critical maintenance access points on the boiler shell. Their core requirement is to maintain an absolute seal during boiler operation to prevent the leakage of high-temperature flue gas and pulverized coal. Existing manhole doors mostly employ a rigid compression sealing structure, where a locking mechanism applies mechanical preload to the door cover, compressing a fixed sealing ring (such as graphite packing) to achieve a seal. This static sealing method has inherent technical defects.

[0003] During boiler operation, internal pressure fluctuates. Traditional sealing structures rely solely on initial tightening; as internal pressure rises, this force attempts to pry open the cover, directly counteracting and weakening the original sealing pressure, easily leading to insufficient sealing pressure and leakage. Furthermore, sealing materials age and creep under long-term high-temperature environments, causing pre-tightening and further exacerbating the risk of leakage. To address the problems caused by pressure fluctuations, some self-tightening sealing designs have emerged in existing technologies; however, these are typically complex in structure or fail to effectively integrate compensation mechanisms for long-term creep of the sealing material. For most structures using simple sealing rings, the sealing effect passively diminishes after tightening, unable to dynamically respond to changes in operating conditions, making reliability difficult to guarantee.

[0004] To address the aforementioned issues, this application provides a manhole door structure for a pulverized coal boiler. Utility Model Content

[0005] The purpose of this utility model is to provide a manhole door structure for pulverized coal boilers in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model specifically adopts the following technical solution: A manhole door structure for a pulverized coal boiler includes a door frame, a door cover, a sealing mechanism, and a locking mechanism, wherein: The door frame is circular well-shaped; The door cover is circular and is hinged to one side of the door frame via a connecting bracket. One side of the door cover has an annular sealing groove. When the door cover is placed on the inlet and outlet ends of the door frame, one end of the door frame is movably locked inside the sealing groove. The sealing mechanism is located inside the sealing groove and is used to seal the door frame and the door cover. The sealing mechanism can change the sealing effect according to the pressure changes inside the pulverized coal boiler. The locking mechanism is used to lock the door frame and the door cover.

[0007] Furthermore, the sealing mechanism includes a sealing ring gasket and a movable plate 1 movably disposed inside the sealing groove. The outer and inner circumferential sides of the sealing ring gasket and the movable plate 1 are both in contact with the sealing groove. Two mounting holes are constructed on one side of the door cover. One of the mounting holes communicates with the sealing groove, and the other mounting hole penetrates the door cover. The sealing mechanism also includes a U-shaped guide tube. The two ends of the U-shaped guide tube are respectively fixedly inserted into the two mounting holes. The movable plate 1 is close to one of the mounting holes that communicates with the sealing groove. When the pressure inside the pulverized coal boiler increases, the pressure inside the sealing groove is balanced through the U-shaped guide tube.

[0008] Furthermore, a second movable plate is movably disposed inside the sealing groove. The outer and inner circumferential sides of the second movable plate are both in contact with the sealing groove. The second movable plate is close to one of the mounting holes that communicates with the sealing groove. Several evenly distributed elastic compensation components are connected between the second movable plate and the first movable plate.

[0009] Furthermore, the elastic compensation component includes several butterfly springs stacked sequentially, and positioning rings are fixed on the opposite side of the first movable plate and the second movable plate, with the two outermost butterfly springs located inside the two positioning rings respectively.

[0010] Furthermore, the bottom side of the door cover has a mounting groove that communicates with one of the mounting holes, and a filter plate is movably mounted on the mounting groove. The filter plate is detachably connected to the door cover by screws.

[0011] Furthermore, the locking mechanism includes a fixed plate, a screw, and a rotating handle. There are two fixed plates, which are respectively fixed to the door frame and the door cover. The rotating handle is fixed to one end of the screw. The other end of the screw movably passes through one of the fixed plates and is threaded through the other fixed plate. A limit block is fixed on the screw.

[0012] Furthermore, a locking nut is threaded onto the screw.

[0013] Furthermore, the number of locking mechanisms is not less than two and they are evenly distributed.

[0014] Compared with the prior art, the beneficial effects of this utility model are: 1. This solution uses a U-shaped conduit connected to the inside of the boiler to dynamically connect the pressure at the rear end of the sealing groove with that at the front end (inside the boiler). When the pressure inside the boiler increases, the high-pressure medium quickly enters the rear end of the sealing groove through the U-shaped conduit and acts on the movable plate. This pressure is opposite to the force that pushes the movable plate to open the door cover, thus pressing the sealing ring gasket. This causes the sealing pressure to automatically increase as the internal pressure increases, successfully transforming the adverse factors that lead to leakage into the power to enhance the seal. This fundamentally solves the problem of leakage caused by the weakening of the sealing force under pressure-boosting conditions in traditional structures.

[0015] 2. This solution establishes a highly efficient elastic compensation system by installing a butterfly spring assembly between movable plate one and movable plate two. The butterfly spring possesses excellent characteristics of large displacement and stable load. When the sealing ring gasket ages or creeps due to long-term high temperatures, resulting in a reduction in thickness, the preload of the butterfly spring drives movable plate one and movable plate two to move towards each other, automatically and continuously compensating for the relaxation of the clamping force caused by the deformation of the sealing material. This maintains the long-term stability of the sealing interface, significantly extending the service life and maintenance cycle of the seal.

[0016] 3. This solution integrates the dynamic pressure response mechanism (U-shaped guide tube, movable plate) and the elastic compensation mechanism (butterfly spring assembly) into the sealing groove of the door cover. The structure is compact and reasonable. The sealing mechanism consists entirely of mechanical components, without complex circuits or external power sources. It is resistant to high temperatures and dust, operates reliably, and eliminates the need for frequent adjustments. At the same time, the detachable filter plate can effectively prevent coal dust particles from clogging the U-shaped guide tube, ensuring the long-term unobstructed pressure transmission channel. Maintenance and operation are simple and quick.

[0017] 4. This solution employs a double locking mechanism using a screw and a locking nut, and by setting no fewer than two evenly distributed locking points, it ensures the uniformity and reliability of the locking force between the door cover and the door frame. The limit block prevents the screw from being excessively screwed out, further improving the safety and convenience of operation. Attached Figure Description

[0018] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This utility model Figure 1 A three-dimensional sectional view; Figure 3 This utility model Figure 2 An enlarged view of structure A in the middle; Figure 4 This utility model Figure 1 A three-dimensional sectional view from another direction; Figure 5 This utility model Figure 1 A schematic diagram of the three-dimensional structure in another state.

[0019] In the diagram: 1. Door frame; 2. Door cover; 21. Connecting bracket; 22. Sealing groove; 23. Mounting hole; 24. Mounting groove; 25. Filter plate; 3. Sealing mechanism; 31. Sealing ring gasket; 32. Movable plate one; 33. U-shaped guide tube; 34. Movable plate two; 35. Elastic compensation component; 351. Butterfly spring; 352. Positioning ring; 4. Locking mechanism; 41. Fixed plate; 42. Screw; 43. Rotating handle; 44. Limit block; 45. Locking nut. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0021] This application provides a manhole door structure for a pulverized coal boiler. Existing manhole doors mostly employ a rigid compression sealing structure, where a locking mechanism applies mechanical pre-tightening force to the door cover, compressing a fixed sealing ring such as graphite packing to achieve a seal. This static sealing method has inherent technical defects. During boiler operation, internal pressure fluctuates. The sealing force of traditional structures only comes from the initial locking. When internal pressure increases, the force attempts to open the door cover, directly resisting and weakening the original sealing compression force, easily leading to insufficient sealing pressure and leakage. Furthermore, sealing materials age and creep under long-term high-temperature environments, causing pre-tightening force to loosen, further exacerbating the leakage risk. The following technical solution is provided, which will be discussed in conjunction with… Figures 1-5 Please provide a detailed explanation: The present invention discloses a manhole door structure for a pulverized coal boiler, comprising a door frame 1, a door cover 2, a sealing mechanism 3, and a locking mechanism 4.

[0022] Door frame 1 is circular and well-shaped, and is welded and fixed to the boiler shell; The door cover 2 is circular and is hinged to one side of the door frame 1 via a connecting bracket 21 to enable the opening and closing of the door cover 2. One side of the door cover 2 is constructed with an annular sealing groove 22. When the door cover 2 covers the inlet and outlet ends of the door frame 1, one end of the door frame 1 is movably locked inside the sealing groove 22, providing precise positioning and accommodating space for sealing. The sealing mechanism 3 is located inside the sealing groove 22 and is used to seal the door frame 1 and the door cover 2. The sealing mechanism 3 can change the sealing effect according to the pressure change inside the pulverized coal boiler. The locking mechanism 4 is used to lock the door frame 1 and the door cover 2.

[0023] For details, please refer to Figure 2 , Figure 3 , Figure 4 and Figure 5The sealing mechanism 3 includes a sealing ring gasket 31 and a movable plate 32 movably disposed inside the sealing groove 22. The sealing ring gasket 31 is made of flexible graphite composite gasket, which has a high upper temperature resistance and excellent compression resilience. The outer and inner circumferences of the sealing ring gasket 31 and the movable plate 32 are both in contact with the sealing groove 22. This fit ensures that the two can slide freely along the axial direction in the groove while effectively isolating the medium and forming an independent pressure chamber. Two mounting holes 23 are constructed on one side of the door cover 2. One mounting hole 23 is connected to the sealing groove 22, and the other mounting hole 23 penetrates the door cover 2. The sealing mechanism 3 also includes a U-shaped guide tube 33, the two ends of which are firmly inserted into the two mounting holes 23 by welding or interference fit, thereby physically forming a permanent pressure transmission channel connecting the high-pressure area inside the boiler and the low-pressure chamber at the rear end of the sealing groove 22.

[0024] When the internal pressure of the pulverized coal boiler increases, the high-pressure medium (such as flue gas) immediately enters the U-shaped guide tube 33 through the mounting hole 23 penetrating the manhole cover 2, and is instantly guided to the rear of the movable plate 32 inside the sealing groove 22. This pressure then acts on the entire back of the movable plate 32, pushing it to apply an additional clamping force proportional to the internal pressure to the sealing ring gasket 31. This implementation method does not simply "balance" the pressure, but actively transforms the pressure of the medium that causes leakage into an effective load that enhances the seal, creatively realizing a "pressure self-tightening seal." The direct benefit is that the sealing performance of the manhole door no longer decreases with fluctuations in boiler operating conditions, but instead reaches its optimal state under the most severe high-pressure conditions. This fundamentally overturns the passive situation of traditional static sealing and greatly improves the sealing reliability of the equipment under varying operating conditions.

[0025] Furthermore, in order to achieve long-term and stable compensation for sealing performance, this utility model has made further optimizations. A second movable plate 34 is movably arranged inside the sealing groove 22. The outer and inner circumferential sides of the second movable plate 34 are in contact with the sealing groove 22 to ensure that it can slide stably along the axial direction. The second movable plate 34 is close to one of the mounting holes 23 that are connected to the sealing groove 22. Several evenly distributed elastic compensation components 35 are connected between the second movable plate 34 and the first movable plate 32. The elastic compensation assembly 35 includes several stacked butterfly springs 351. To ensure that the spring assembly does not become unstable or tilted under pressure, positioning rings 352 are fixedly installed on the opposite side of the movable plate 32 and the movable plate 34. During assembly, the entire butterfly spring assembly 351 is constrained within the space enclosed by the positioning rings 352 at both ends, with the ends of the two outermost butterfly springs 351 respectively fitted inside the corresponding positioning rings 352.

[0026] This elastic system, composed of butterfly springs 351, is pre-compressed when the door cover 2 is initially locked, storing sufficient elastic potential energy. When the sealing ring gasket 31 inevitably ages and creeps under the combined effects of long-term high temperature and pressure, resulting in a reduction in its thickness, the space within the sealing groove 22 used to compress it will slightly increase. At this time, the butterfly springs 351, which are always in a compressed state, will release their stored elastic potential energy, continuously and stably pushing the movable plate 32 and the movable plate 34 to move towards each other, thereby automatically and accurately compensating for the portion of the clamping force lost due to the permanent deformation of the sealing material. The significant benefit of this ingenious passive compensation mechanism is that it effectively counteracts the natural degradation of material properties, allowing the sealing interface to maintain a near-constant optimal clamping state for a long time, greatly delaying the leakage process caused by seal loosening, thus significantly extending the service life and maintenance cycle of the seals and improving the long-term reliability of the equipment.

[0027] In this embodiment, to ensure the long-term reliability and continuity of the pressure transmission channel of the present invention, the bottom side of the door cover 2 is constructed with a mounting groove 24 that communicates with one of the mounting holes 23. A filter plate 25 is movably mounted on the mounting groove 24, preferably made of sintered metal mesh, which has excellent mechanical strength and high temperature resistance, and is detachably and firmly connected to the door cover 2 by screws. This design places the filter plate 25 directly opposite and covers the inlet of the boiler's internal medium inlet mounting hole 23. When the boiler is running, the high-temperature flue gas containing pulverized coal particles flows through this area, and most of the solid particles are effectively intercepted by the filter plate 25. This implementation directly prevents the U-shaped conduit 33 and its connected pores from being blocked by pulverized coal at the source, ensuring that the pressure can be transmitted sensitively and without attenuation to the rear of the sealing groove 22. The direct benefit is that it ensures the consistency of the core function of "pressure self-tightening," avoiding the risk of seal failure due to channel blockage. At the same time, the detachable connection method provides great convenience for maintenance. During regular maintenance, maintenance personnel only need to unscrew the screws to remove the filter plate 25 for cleaning or replacement, thus ensuring the functional integrity and reliable operation of the entire self-tightening sealing system throughout its entire life cycle with extremely low maintenance costs.

[0028] Furthermore, to achieve a reliable and uniform locking seal between the door cover 2 and the door frame 1, please refer to... Figure 2 , Figure 4 and Figure 5The locking mechanism 4 includes a fixed plate 41, a screw 42, and a rotating handle 43. There are two fixed plates 41, which are fixed to the door frame 1 and the door cover 2 respectively. The rotating handle 43 is fixed to one end of the screw 42. The other end of the screw 42 passes through one of the fixed plates 41 with a clearance fit, and then screws into and passes through the threaded hole on the other fixed plate 41 with a threaded fit. A limit block 44 is fixed on the screw 42. When closing the manhole door, the operator drives the screw 42 to screw in by rotating the handle 43. Using the transmission principle of the threaded pair, the rotational motion is converted into linear motion, thereby forcefully pulling the distance between the door cover 2 and the door frame 1 closer, providing the necessary initial pre-tightening force for the sealing mechanism 3. This design achieves the effect of obtaining a huge locking force with a small operating force through simple mechanical transmission, ensuring the establishment of the initial seal. To further improve the reliability of locking and prevent loosening that may occur due to vibration during boiler operation, this utility model also provides a locking nut 45 threaded onto the screw 42. The operation and its beneficial effects are as follows: after the screw 42 is tightened to the correct position, the locking nut 45 can be tightened further, ensuring its end face is firmly against the fixing plate 41. This adds a mechanical anti-loosening safety measure. Through the friction between the threaded parts and the supporting force of the nut end face, a reliable double locking mechanism is formed, effectively resisting vibration and impact and eliminating the possibility of the screw 42 spontaneously retracting. The locking mechanism 4 consists of four evenly distributed mechanisms, which ensures that the clamping force of the door cover 2 on the door frame 1 is uniform and symmetrical on the circumference, thereby avoiding poor sealing caused by insufficient local clamping force. From the overall structure, it ensures that the sealing ring gasket 31 can be uniformly compressed, achieving a comprehensive and reliable sealing effect.

[0029] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A manhole door structure for a pulverized coal boiler, comprising a door frame (1), a door cover (2), a sealing mechanism (3), and a locking mechanism (4), characterized in that, in: The door frame (1) is circular; The door cover (2) is circular and is hinged to one side of the door frame (1) via a connecting bracket (21). One side of the door cover (2) is constructed with an annular sealing groove (22). When the door cover (2) covers the inlet and outlet ends of the door frame (1), one end of the door frame (1) is movably locked inside the sealing groove (22). The sealing mechanism (3) is located inside the sealing groove (22) and is used to seal the door frame (1) and the door cover (2). The sealing mechanism (3) can change the sealing effect according to the pressure change inside the pulverized coal boiler. The locking mechanism (4) is used to lock the door frame (1) and the door cover (2).

2. The manhole door structure for a pulverized coal boiler according to claim 1, characterized in that: The sealing mechanism (3) includes a sealing ring gasket (31) and a movable plate (32) movably disposed inside the sealing groove (22). The outer and inner circumferential sides of the sealing ring gasket (31) and the movable plate (32) are both in contact with the sealing groove (22). Two mounting holes (23) are constructed on one side of the door cover (2). One of the mounting holes (23) is connected to the sealing groove (22), and the other mounting hole (23) penetrates the door cover (2). The sealing mechanism (3) also includes a U-shaped guide tube (33). The two ends of the U-shaped guide tube (33) are respectively fixedly inserted into the two mounting holes (23). The movable plate (32) is close to one of the mounting holes (23) connected to the sealing groove (22). When the pressure inside the pulverized coal boiler increases, the pressure inside the sealing groove (22) is balanced through the U-shaped guide tube (33).

3. The manhole door structure for a pulverized coal boiler according to claim 2, characterized in that: The sealing groove (22) is movably provided with a second movable plate (34). The outer and inner circumferential sides of the second movable plate (34) are in contact with the sealing groove (22). The second movable plate (34) is close to one of the mounting holes (23) that are connected to the sealing groove (22). A number of evenly distributed elastic compensation components (35) are connected between the second movable plate (34) and the first movable plate (32).

4. The manhole door structure for a pulverized coal boiler according to claim 3, characterized in that: The elastic compensation component (35) includes several butterfly springs (351) stacked in sequence. Positioning rings (352) are fixed on the side opposite to the movable plate one (32) and the movable plate two (34). The two outermost butterfly springs (351) are located inside the two positioning rings (352) respectively.

5. The manhole door structure for a pulverized coal boiler according to claim 2, characterized in that: The bottom side of the door cover (2) has a mounting groove (24) that communicates with one of the mounting holes (23). A filter plate (25) is movably mounted on the mounting groove (24). The filter plate (25) is detachably connected to the door cover (2) by screws.

6. The manhole door structure for a pulverized coal boiler according to claim 1, characterized in that: The locking mechanism (4) includes a fixed plate (41), a screw (42) and a rotating handle (43). There are two fixed plates (41) and they are fixed on the door frame (1) and the door cover (2) respectively. The rotating handle (43) is fixed to one end of the screw (42). The other end of the screw (42) moves through one of the fixed plates (41) and is threaded through the other fixed plate (41). A limit block (44) is fixed on the screw (42).

7. The manhole door structure for a pulverized coal boiler according to claim 6, characterized in that: A locking nut (45) is threaded onto the screw (42).

8. The manhole door structure for a pulverized coal boiler according to claim 7, characterized in that: The number of locking mechanisms (4) is not less than two and they are evenly distributed.

Images