Sealing structure of secondary air box of coal-fired boiler

Abstract

The utility model discloses a kind of secondary air box sealing structure of coal-fired boiler, belong to boiler sealing technical field, including, water-cooled wall embedded part, fixedly connected to water-cooled wall;Sealing plate, fixedly connected to water-cooled wall embedded part;Metal expansion compensation plate, upper portion with the metal sealing plate fixed connection, lower portion is overlapped with sealing plate, forms cavity;Filling material, filled in cavity, filling material includes micro-expansion fire-resistant plastic material and sira blanket, micro-expansion fire-resistant plastic material, filled in the bottom of cavity;Sira blanket, laid on micro-expansion fire-resistant plastic material and filled the remaining space of cavity;The utility model can better dynamically absorb boiler expansion, avoid metal sealing structure to be pulled crack, also reduced air blower power consumption, reduce dust pollution etc., good secondary air box sealing structure can also better reduce heat dissipation, help to improve coal-fired unit economy.

Description

Technical Field

[0001] This utility model relates to the field of boiler sealing technology, and more specifically, to a sealing structure for the secondary air box of a coal-fired boiler. Background Technology

[0002] After several changes in operating conditions from cold to hot, the boiler of a coal-fired steam turbine generator unit may experience cracking of the metal seals, ash leakage from the secondary air box, and overheating due to factors such as large displacement changes in the components of the boiler drum, large changes in thermal stress, and insufficient expansion of the metal seals.

[0003] Because the boiler's secondary air box is under positive pressure during operation, factors such as the original secondary air box structure design, differences between the type of coal used in the boiler and the design coal type, and improper installation of the original metal sealing structure during infrastructure construction can all lead to tearing of the metal seal, resulting in ash and air leakage. However, traditional secondary air box sealing treatments use elastic metal sheets welded to water-cooled wall embedded parts, which cannot effectively resist the expansion of the boiler flask, causing the original metal seal to tear frequently, thus preventing the boiler from operating safely and stably. Utility Model Content

[0004] To address the problems existing in the prior art, the purpose of this utility model is to provide a secondary air box sealing structure for coal-fired boilers. This structure aims to solve the problem that traditional secondary air box sealing methods, which rely on welding elastic metal sheets to embedded parts in the water-cooled wall, cannot effectively resist the expansion of the boiler drum, leading to frequent tearing of the original metal seal and thus preventing the boiler from operating safely and stably.

[0005] This utility model adopts the following technical solution: a sealing structure for a secondary air box of a coal-fired boiler, comprising: Water-cooled wall embedded parts are fixedly connected to the water-cooled wall; The sealing plate is fixedly connected to the embedded parts of the water-cooled wall; The metal expansion compensation plate is fixedly connected to the metal sealing plate at the top and overlaps with the sealing plate at the bottom to form a cavity. Filling material, used to fill cavities.

[0006] As a preferred embodiment of this utility model, the filling material includes: Micro-expansion refractory plastic is filled at the bottom of the cavity; Sera blankets are laid on top of micro-expanding refractory plastic and fill the remaining space in the cavity.

[0007] As a preferred embodiment of this utility model, the overlap between the metal expansion compensation plate and the sealing plate is a transverse overlap.

[0008] As a preferred embodiment of this utility model, the overlap length between the metal expansion compensation plate and the sealing plate is 40-50mm.

[0009] As a preferred embodiment of this utility model, the water-cooled wall embedded part is prefabricated at the factory and fixed to the water-cooled wall by welding.

[0010] In a preferred embodiment of this utility model, the sealing plate and the water-cooled wall embedded part are fixedly connected by welding.

[0011] In a preferred embodiment of this utility model, the upper part of the metal expansion compensation plate is fixedly connected to the sealing plate by welding.

[0012] As a preferred embodiment of this utility model, it also includes a secondary air box bottom plate, wherein the metal expansion compensation plate is fixedly connected to the secondary air box bottom plate.

[0013] In a preferred embodiment of this utility model, the metal expansion compensation plate is a stainless steel plate.

[0014] In a preferred embodiment of this utility model, the sealing plate is a steel plate.

[0015] Beneficial effects Compared with existing technologies, the advantages of this utility model are: 1. This utility model can better dynamically absorb boiler expansion, avoid the metal sealing structure from cracking, and also reduce the power consumption of the blower and reduce dust pollution. The good secondary air box sealing structure can also better reduce heat dissipation, which helps to improve the economy of coal-fired units. Attached Figure Description

[0016] Figure 1 This is a plan view of the present invention.

[0017] Explanation of the labels in the diagram: 1. Water-cooled wall embedded parts; 2. Metal expansion compensation plate; 3. Secondary air box bottom plate; 4. Sera blanket; 5. Micro-expansion refractory plastic; 6. Sealing plate. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0019] In the description of this utility model, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0021] Example: Please see Figure 1 A sealing structure for a secondary air box of a coal-fired boiler includes a water-cooled wall embedded part 1, a metal expansion compensation plate 2, a sealing plate 6, a Sera blanket 4, and a micro-expansion refractory plastic 5. The water-cooled wall embedded part 1 is welded to the water-cooled wall, the sealing plate 6 is welded to the water-cooled wall embedded part 1, the metal expansion compensation plate 2 is welded to the sealing plate 6, the metal expansion compensation plate 2 and the sealing plate 6 are freely overlapped to form a cavity structure, the bottom of the cavity is filled with micro-expansion refractory plastic 5, the top of the micro-expansion refractory plastic 5 is filled with Sera blanket 4, and the secondary air box bottom plate 3 is welded and fixed to the metal expansion compensation plate 2.

[0022] It should be noted that: Micro-expansion refractory plastic 5 is an unshaped refractory material made of refractory aggregate, binder, micro-expansion agent and additives mixed in a specific ratio. It has good high-temperature volume stability and hot strength. It has strong plasticity at room temperature and is easy to fill into the complex gaps at the bottom of the cavity. After baking and curing, it can form a dense integral structure, which can effectively block the penetration of high-temperature flue gas and dust. At the same time, its micro-expansion characteristics can compensate for the shrinkage of the material during use, avoid cracking, and thus ensure the long-term stability of the sealed structure. The metal expansion compensation plate 2 is made of 1Cr18Ni9Ti stainless steel plate. This material has excellent high temperature resistance and oxidation resistance, and is not prone to deformation or corrosion in the high temperature environment of boiler operation. The sealing plate 6 is made of Q235 steel plate with a thickness of 6mm. It has good structural strength and welding performance. It is fixedly connected to the water-cooled wall embedded part 1 by welding. It can stably bear the load brought by the metal expansion compensation plate 2 and the filling material, and form a solid connection foundation with the water-cooled wall embedded part 1 to ensure the overall stability of the sealing structure. Similarly, the upper part of the metal expansion compensation plate 2 is also connected to the sealing plate 6 by welding. This multiple fixed connection method further improves the overall rigidity of the sealing structure. The water-cooled wall embedded part 1 is a prefabricated part manufactured at the factory. During installation, it is firmly fixed to the water-cooled wall by welding, ensuring the basic connection strength of the entire sealing structure.

[0023] All of the above are components well known to those skilled in the art and can be replaced according to actual needs, so they will not be described in detail here.

[0024] The non-closed cavity structure formed by the metal expansion compensation plate 2 and the sealing plate 6 is elastic and can expand within a certain range in the vertical and horizontal directions. This counteracts the tension caused by the difference in expansion stroke between the water-cooled wall and the secondary air box, preventing the sealing parts from cracking and causing ash leakage during the operation of the secondary air box.

[0025] In this application, the upper part is filled with Sera blanket 4. Sera blanket 4 has good expansion performance. When laid on micro-expansion refractory plastic 5, it can not only fill the remaining space of the cavity, but also play a good buffering and compensation role during the expansion and contraction of the boiler, avoiding damage to the filling material due to compression or stretching. At the same time, it can fill the gap to the maximum extent when the upper expansion wave is pulled open, reducing heat transfer. The lower part is a semi-enclosed structure, so in order to prevent the Sera blanket 4 from leaking out along the gap, a micro-expansion refractory plastic 5 with low expansion is used; The combination of filling materials fully utilizes the characteristics of different materials. Micro-expansion refractory plastic 5 will expand slightly under high temperature environment, which can tightly fill the bottom of the cavity and effectively block the penetration of high temperature flue gas and dust.

[0026] Among them, the overlap between the metal expansion compensation plate 2 and the sealing plate 6 is a transverse overlap with an overlap length of 40-50mm. The horizontal overlapping design allows the metal expansion compensation plate 2 to freely expand and contract in the horizontal direction during boiler operation, effectively buffering the thermal expansion stress caused by temperature changes and avoiding the problem of easy cracking of the sealing structure under the traditional rigid connection method. In addition, the cavity structure formed by the transverse overlap provides a stable space for the filling material, allowing the micro-expansion refractory plastic 5 and the serara blanket 4 to be filled in layers and give full play to their respective properties, further improving the sealing effect and structural durability.

[0027] This structure has better tensile strength and can better dynamically absorb boiler expansion, avoiding the metal sealing structure from cracking. This completely solves the problem of ash leakage from the boiler's secondary air box, while also reducing the power consumption of the blower and reducing ash leakage pollution. This helps improve the economic efficiency of coal-fired units. It also solves the problem that traditional secondary air box sealing treatments, which use elastic metal sheets welded to water-cooled wall embedded parts 1, cannot effectively resist the expansion of the boiler flask, causing the original metal seal to tear frequently, thus preventing the boiler from operating safely and stably.

[0028] 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 its improved concept should be covered within the protection scope of the present utility model.

Claims

1. A sealing structure for a secondary air box of a coal-fired boiler, characterized in that, include: Water-cooled wall embedded part (1) is fixedly connected to the water-cooled wall; The sealing plate (6) is fixedly connected to the water-cooled wall embedded part (1); The metal expansion compensation plate (2) is fixedly connected to the metal sealing plate (6) at its upper part and overlaps with the sealing plate (6) at its lower part to form a cavity; Filling material, used to fill cavities.

2. The sealing structure of a secondary air box for a coal-fired boiler according to claim 1, characterized in that: The filler material includes: Micro-expansion refractory plastic (5) is filled at the bottom of the cavity; Sera blanket (4) is laid on top of micro-expanded refractory plastic (5) and fills the remaining space of the cavity.

3. The sealing structure of a secondary air box for a coal-fired boiler according to claim 2, characterized in that: The metal expansion compensation plate (2) and the sealing plate (6) overlap in a transverse manner.

4. The sealing structure of a secondary air box for a coal-fired boiler according to claim 3, characterized in that: The overlap length between the metal expansion compensation plate (2) and the sealing plate (6) is 40-50mm.

5. The sealing structure of a secondary air box for a coal-fired boiler according to claim 1, characterized in that: The water-cooled wall embedded part (1) is prefabricated at the factory and fixed to the water-cooled wall by welding.

6. The sealing structure of a secondary air box for a coal-fired boiler according to claim 1, characterized in that: The sealing plate (6) is fixedly connected to the water-cooled wall embedded part (1) by welding.

7. The sealing structure of a secondary air box for a coal-fired boiler according to claim 1, characterized in that: The upper part of the metal expansion compensation plate (2) is fixedly connected to the sealing plate (6) by welding.

8. The sealing structure of a secondary air box for a coal-fired boiler according to claim 1, characterized in that: It also includes a secondary air box base plate (3), and the metal expansion compensation plate (2) is fixedly connected to the secondary air box base plate (3).

9. The sealing structure of a secondary air box for a coal-fired boiler according to claim 1, characterized in that: The metal expansion compensation plate (2) is a stainless steel plate.

10. The sealing structure of a secondary air box for a coal-fired boiler according to claim 1, characterized in that: The sealing plate (6) is a steel plate.

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