A boiler drum manhole door gasket

Abstract

The utility model discloses a kind of boiler drum manhole door sealing gasket, belong to mechanical sealing technical field.The sealing gasket, including gasket body, gasket body includes matrix and embedded reinforcing layer, cavity is provided in the inside of matrix, embedded reinforcing layer is set in cavity, matrix is made of XB510 high-pressure asbestos material, embedded reinforcing layer is high-temperature-resistant nickel wire braided net;The edge of gasket body is equipped with anti-breaking edge covering structure, anti-breaking edge covering structure uses stainless steel sheet or high-temperature-resistant rubber strip, the utility model is in by setting the embedded reinforcing layer of high-temperature-resistant nickel wire braided net in matrix, make gasket body form the laminar reinforcing structure of inside nickel wire clamping, improve the strength, flexibility, extrusion resistance, deformation resistance, high-temperature resistance of gasket body, and finally reach the goal that drum manhole door sealing does not leak.

Description

Technical Field

[0001] This utility model relates to the field of mechanical seal technology, and more specifically, to a sealing gasket for a boiler drum manhole. Background Technology

[0002] As the core hub of the power plant boiler's heating, vaporization, and superheating processes, the boiler drum operates in an environment characterized by high pressure (typically above 16 MPa), high temperature (medium temperature reaching around 350℃), and frequent parameter fluctuations. Therefore, the reliability of the manhole door gaskets directly affects the safe, stable operation and economy of the unit. Under complex operating conditions such as deep peak shaving, the rapid changes in internal pressure and temperature of the boiler drum place stringent requirements on the mechanical properties, thermal stability, and fatigue resistance of the gaskets.

[0003] Traditional sealing gaskets, such as 1 mm high-pressure asbestos gaskets, while possessing a certain initial sealing capability, reveal significant defects during long-term operation: their thinness and lack of elastic support structure make them prone to plastic deformation and embrittlement under high temperature and pressure environments, leading to seal failure. While metal spiral wound gaskets offer some compression margin, the internal graphite is easily broken under hot conditions, resulting in insufficient resilience. Furthermore, bending deformation during cold installation leads to a significant decrease in toughness under hot conditions, making them unsuitable for the repeated start-stop cycles and load fluctuations of steam drum manhole doors.

[0004] The aforementioned problems may lead to leakage of high-temperature and high-pressure media, threatening not only the safety of maintenance personnel but also damaging the steam drum mating surfaces, causing unscheduled unit shutdowns, resulting in significant economic losses and risks to the stability of the power grid's heating supply. Therefore, we propose a boiler steam drum manhole sealing gasket. Utility Model Content

[0005] The purpose of this utility model is to provide a sealing gasket for the manhole door of a boiler drum, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A boiler drum manhole sealing gasket includes a gasket body, the gasket body includes a substrate and an embedded reinforcing layer, the substrate has a cavity inside, the embedded reinforcing layer is disposed in the cavity, the substrate is made of XB510 high-pressure asbestos material, and the embedded reinforcing layer is a high-temperature resistant nickel wire woven mesh.

[0008] The edge of the gasket body is provided with a damage-proof edge banding structure, which is made of stainless steel sheet or high-temperature resistant rubber strip.

[0009] Preferably, both sealing surfaces of the substrate are coated with a lithium molybdenum disulfide grease lubricating layer with a thickness of 0.08±0.02mm, covering the full contact area 10mm inward from the edge of the sealing surface.

[0010] Preferably, the molybdenum disulfide lithium-based grease lubricating layer uses a composite lubricating material with a thermal stability of ≥260℃.

[0011] Preferably, the substrate and the embedded reinforcing layer are bonded together at the interface using a high-temperature resistant adhesive, wherein the high-temperature resistant adhesive is selected with a temperature resistance of ≥550℃ and a bonding strength of ≥1.5MPa.

[0012] Preferably, the high-temperature resistant nickel wire woven mesh is made of pure nickel wire with a diameter of 0.2±0.05mm woven in an orthogonal grid pattern.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0014] This invention improves the gasket's strength, resilience, extrusion resistance, deformation resistance, and high-temperature resistance by embedding a high-temperature resistant nickel wire braided mesh within the substrate, creating a layered reinforcement structure with embedded nickel wire. This ultimately achieves the goal of sealing the steam drum manhole door without leakage. The high-temperature resistant nickel wire braided mesh, through a triple mechanism of mechanical strengthening, thermal stability optimization, and sealing path blocking, works synergistically with the substrate, edging, and lubrication layer to comprehensively enhance the safety performance of the steam drum manhole door sealing gasket, significantly reduce leakage risk, and strengthen its resistance to extreme operating conditions. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0016] Figure 2 This is a cross-sectional view of the overall structure of this utility model.

[0017] The labels in the diagram are as follows: 1. Substrate; 2. Embedded reinforcement layer; 3. Anti-damage edging. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0019] Example:

[0020] Please see Figure 1-2A boiler drum manhole sealing gasket includes a gasket body, comprising a substrate 1 and an embedded reinforcing layer 2. The substrate 1 has an internal cavity, within which the embedded reinforcing layer 2 is disposed. The substrate 1 is made of XB510 high-pressure asbestos material, and the embedded reinforcing layer 2 is a high-temperature resistant nickel wire woven mesh. The embedded reinforcing layer 2 creates a layered reinforcing structure with embedded nickel wire in the gasket body, improving its strength, resilience, extrusion resistance, deformation resistance, and high-temperature resistance, ultimately achieving the goal of leak-proof sealing of the boiler drum manhole. Pressure / temperature cycles caused by deep peak shaving (such as 1-2 start-ups and shutdowns per day) can lead to fatigue damage to the gasket body. The high elastic modulus and elongation of the nickel wire can absorb alternating load energy, improving the fatigue life of the gasket body and preventing leakage due to fatigue cracking of the asbestos layer. The coefficient of thermal expansion of nickel wire lies between that of asbestos and stainless steel flanges. Through the interlayer effect, it reduces interfacial thermal stress and inhibits cracking of the substrate 1 caused by temperature differences. Simultaneously, the high thermal conductivity of nickel wire can evenly distribute the internal temperature field of the gasket, preventing asbestos embrittlement caused by localized overheating. During long-term operation at 350℃, the creep strain rate of the nickel wire is ≤0.01% / year, ensuring stable gasket compression allowance and preventing seal failure due to creep relaxation.

[0021] The edge of the gasket body is provided with a breakage-resistant edging 3, which is made of stainless steel sheet or high-temperature resistant rubber strip. The stainless steel edging suppresses edge cracking through rigid support and allows the gasket to bend 45° in a cold state without deformation; the high-temperature resistant rubber edging (such as silicone rubber) absorbs stress through elastic buffering, and the edge is undamaged after bending and recovery.

[0022] In this application, both sealing surfaces of the substrate 1 are coated with a lithium molybdenum disulfide grease lubricating layer, with a thickness of 0.08±0.02mm, covering the entire contact area 10mm inward from the edge of the sealing surface. The surface roughness of the manhole sealing surface of the steam drum is typically Ra 6.3-12.5μm. The friction coefficient of the traditional lead powder coating process is approximately 0.25-0.3, while the friction coefficient of the lithium molybdenum disulfide grease is 0.08-0.12. This significantly reduces the friction between the gasket and the flange, allowing for a more uniform application of the 4018 N·m torque and preventing gasket misalignment due to uneven friction. Full contact area coverage ensures 100% lubrication of the sealing surface, preventing hot spot wear caused by localized dry friction.

[0023] In this application, the molybdenum disulfide lithium-based grease lubricating layer uses a composite lubricating material with a thermal stability ≥260℃. The normal operating temperature of the steam drum reaches 350℃, but the base oil of the molybdenum disulfide lithium-based grease (such as synthetic esters) can maintain its liquid lubricating properties below 260℃. Furthermore, the solid lubricating particles of molybdenum disulfide, with a melting point of 1185℃, form a physical adsorption film at high temperatures, ensuring lubrication across the entire temperature range from a cold state of 20℃ to a hot state of 350℃. Compared to traditional calcium-based grease with a thermal stability ≤120℃ and carbonization failure above 200℃, this lubricating layer has no risk of dripping point failure during steam drum heating, avoiding dry friction between the gasket and flange due to lubrication failure.

[0024] In this application, the substrate 1 and the embedded reinforcing layer 2 are bonded together by a high-temperature resistant adhesive. The high-temperature resistant adhesive is selected with a temperature resistance of ≥550℃ and a bonding strength of ≥1.5MPa, which improves the resistance to deformation and fatigue, and inhibits hot delamination and fracture.

[0025] The nickel wire mesh has a smaller mesh spacing than the average length of asbestos fibers, which can block the medium's permeation channels and reduce the steam leakage rate. Simultaneously, the nickel wire and the matrix are integrated through a high-temperature resistant adhesive, avoiding the risk of leakage due to delamination. When the steam drum pressure rises sharply, the elastic deformation of the nickel wire can provide a dynamic compression allowance of 0.2-0.3 mm to compensate for the plastic deformation of the asbestos layer, maintaining the contact stress at the sealing surface above 15 MPa (compared to below 8 MPa for traditional gaskets), ensuring effective sealing.

[0026] In this application, the high-temperature resistant nickel wire braided mesh is woven from pure nickel wire (Ni ≥ 99.5%) with a diameter of 0.2 ± 0.05 mm in an orthogonal mesh pattern. The warp and weft spacing of the nickel wire mesh is 8 ± 2 mm, uniformly embedded in the central region of the XB510 asbestos layer, forming a reinforcing skeleton with a thickness of 20%-30%. Pure nickel wire hardly oxidizes below 500℃, with only a nano-scale NiO film forming on its surface, preventing asbestos layer contamination and failure due to oxide scale peeling. Traditional nickel wire containing impurities has an oxide scale thickness ≥ 1 μm, which is easily broken and embedded in the asbestos layer. High-purity nickel exhibits excellent resistance to corrosive media such as caustic alkali (NaOH) and chlorides in the steam drum, with a corrosion rate ≤ 0.001 mm / year in an alkaline environment with pH = 10-14, ensuring long-term service strength. The nickel wire is woven in an orthogonal mesh pattern, providing equivalent elastic modulus support in both the radial and circumferential directions of the gasket, suppressing uniaxial compressive deformation of the asbestos layer. The mesh structure absorbs impact energy through the micro-deformation of nickel wires during pressure fluctuations, reducing asbestos layer cracking caused by sudden high pressure (such as overpressure conditions).

[0027] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A boiler drum manhole sealing gasket, characterized in that: The gasket body includes a substrate (1) and an embedded reinforcing layer (2). The substrate (1) has a cavity inside, and the embedded reinforcing layer (2) is disposed in the cavity. The substrate (1) is made of XB510 high-pressure asbestos material, and the embedded reinforcing layer (2) is a high-temperature resistant nickel wire woven mesh. The edge of the gasket body is provided with a breakage-proof edging (3), which is made of stainless steel sheet or high-temperature resistant rubber strip.

2. The boiler drum manhole sealing gasket according to claim 1, characterized in that: Both sides of the substrate (1) are coated with a lithium molybdenum disulfide grease lubricating layer with a thickness of 0.08±0.02mm, covering the full contact area 10mm inward from the edge of the sealing surface.

3. A boiler drum manhole sealing gasket according to claim 2, characterized in that: The molybdenum disulfide lithium-based grease lubricating layer uses a composite lubricating material with a thermal stability of ≥260℃.

4. A boiler drum manhole sealing gasket according to claim 1, characterized in that: The substrate (1) and the embedded reinforcing layer (2) are bonded together by a high-temperature resistant adhesive, wherein the high-temperature resistant adhesive is selected with a temperature resistance of ≥550℃ and a bonding strength of ≥1.5MPa.

5. A boiler drum manhole sealing gasket according to claim 1, characterized in that: The high-temperature resistant nickel wire woven mesh is made of pure nickel wire with a diameter of 0.2±0.05mm woven in an orthogonal grid pattern.

Images