A sealing ring for a high-temperature condensate pump and its manufacturing method

Abstract

This invention provides a sealing ring for a high-temperature condensate pump and its manufacturing method. The sealing ring includes a first ring body with an annular groove, a buffer element consisting of a second ring body alternately covered by metal and elastic layers, an outer pressure ring and an inner pressure ring for fixing the buffer element, and a protective coating. The buffer element absorbs impact energy by cooperating with the inner and outer pressure rings through a trapezoidal positioning part. The protective coating adopts a three-layer gradient structure with decreasing thermal expansion coefficients and increasing Cr content. This invention solves the technical problems of insufficient impact resistance, easy detachment of the buffer structure, and poor corrosion resistance of traditional sealing rings under high-temperature, high-pressure water flow impact and frequent start-stop conditions through the synergistic effect of the composite buffer structure and the gradient coating. The manufacturing method provided by this invention uses HVOF spraying technology combined with laser microtexturing processing. The prepared sealing ring has excellent overall impact resistance and a longer service life, which can meet the application requirements of high-temperature condensate pumps in thermal power plants.

Description

Technical Field

[0001] This invention belongs to the field of sealing ring and material surface engineering technology for hydrophobic pumps, specifically relating to a sealing ring for a high-temperature hydrophobic pump and its manufacturing method. Background Technology

[0002] High-temperature condensate pumps are essential auxiliary equipment in the thermal cycle of thermal power plants. By forcibly recovering high-temperature and high-pressure condensate (typically at temperatures of 150-300℃ and pressures of 4-15MPa), they achieve efficient recycling of high-quality working fluid water and thermal energy, significantly improving the economic efficiency and safety of power plants while also reducing thermal and chemical pollution to the environment.

[0003] High-temperature condensate pumps in thermal power plants typically employ multistage centrifugal pumps, also known as multistage pumps. During operation, if the gap between the impeller inlet and the pump casing is too large, water from the high-pressure zone will flow to the low-pressure zone through this gap, affecting the pump's output and reducing efficiency. Conversely, if the gap is too small, friction between the impeller and the pump casing will cause wear, which is particularly severe during start-up and shutdown. Therefore, to increase backflow resistance, reduce internal leakage, and extend the service life of the impeller and pump casing, a sealing ring is usually installed at the junction of the inner edge of the pump casing and the outer edge of the impeller protrusion.

[0004] Chinese utility model patent CN221423455U discloses a multi-stage pump with a honeycomb-shaped sealing ring, including a pump casing, a pump shaft, and impellers. The pump shaft is rotatably supported between bearing seats at both ends of the pump casing, and the impellers are arranged and fixed on the pump shaft. A sealing ring is installed between the inner edge of the pump casing and the outer periphery of the impeller protrusions. The inner surface of the sealing ring is densely covered with blind holes arranged in a honeycomb pattern. The blind holes are arranged in rows along the circumference, with adjacent rows of blind holes staggered. However, under frequent start-stop conditions, fatigue cracks are prone to occur at the edges of the honeycomb structure, increasing the risk of leakage after long-term operation.

[0005] Chinese utility model patent CN201827130U discloses a sealing structure for a large centrifugal pump. The pump body contains a pump shaft with an impeller mounted on it. A sealing ring is located between the impeller hub and the pump body. L-shaped grooves and protrusions are fitted onto the pump body and the sealing ring, with the protrusions on the sealing ring engaging with the L-shaped grooves on the pump body. An O-ring and a locating pin are located between the pump body and the sealing ring. However, this type of O-ring is prone to elastic failure under high-temperature conditions.

[0006] Chinese utility model patent CN211082364U discloses a sealing ring structure for a cooling water pump used in nuclear power plants, including: a pump body, an impeller, a shaft sleeve, a pump cover, a small sealing ring, and a large sealing ring; it employs two sealing rings with different inner diameters, corresponding to different outer diameters at the impeller sealing ring locations; the large and small sealing rings are respectively disposed on the pump body at both ends of the impeller; sealing ring steps are provided at the junctions of the small and large sealing rings with the impeller; and impeller steps are provided on the impeller for proper installation. However, this structure has limited buffering effect against radial water flow impact and is prone to fretting wear under transient operating conditions.

[0007] In summary, existing sealing rings generally suffer from weak impact resistance. Actual measurements show that at the start-up of a multistage pump, the water flow impact force on the sealing ring can reach 5-8 times that under normal operating conditions. Under conditions of frequent start-ups and shutdowns of the multistage pump, the sealing ring is prone to seal failure, causing water to leak from the high-pressure area to the low-pressure area within the pump casing. This affects the pump's discharge head and reduces its efficiency. Furthermore, existing sealing rings also have poor resistance to high temperatures and corrosion. For example, traditional 304 stainless steel sealing rings are susceptible to corrosion when exposed to chloride ions (Cl). - Localized corrosion can occur in the medium, with an annual corrosion depth of up to 0.15 mm.

[0008] Therefore, there is an urgent need to provide a brand-new sealing ring for high-temperature hydrophobic pumps to solve the problems of insufficient impact resistance, easy detachment of buffer structure and poor surface protection performance of existing sealing rings, which lead to sealing failure and shortened service life. Summary of the Invention

[0009] One of the objectives of this invention is to provide a novel sealing ring with a composite buffer structure and a gradient protective coating, in order to solve the technical problems of sealing failure and shortened lifespan of traditional sealing rings in high-temperature condensate pumps under high pressure, high-speed water flow impact and corrosive media environments, due to insufficient impact resistance, easy detachment of the buffer structure and poor surface protection performance.

[0010] The second objective of this invention is to provide a method for manufacturing a sealing ring for a high-temperature hydrophobic pump.

[0011] The third objective of this invention is to provide a novel sealing ring with a composite buffer structure and a gradient protective coating for use in a high-temperature condensate pump in a thermal power plant.

[0012] One of the technical solutions adopted by the present invention to achieve its objective is: providing a sealing ring for a high-temperature hydrophobic pump, disposed between the pump body and the impeller, the sealing ring comprising: The first annular body has an annular groove on its first end face adjacent to the high-voltage zone; A buffer element is disposed within the annular groove, and the buffer element protrudes outward from the annular groove to form a positioning portion; the buffer element includes a second ring body, and a covering layer formed by alternating metal layers and elastic layers covering the outer surface of the second ring body; An outer pressure ring and an inner pressure ring are coaxially disposed on the first ring body and respectively abut against the outer side wall and the inner side wall of the positioning part to press and fix the buffer member. A coating is applied to the outer pressure ring, the inner pressure ring, and the area where the first end face contacts the high-pressure zone; the coefficient of thermal expansion of the coating decreases from the inside to the outside, while the Cr content increases.

[0013] This invention provides a sealing ring for a high-temperature condensate pump, which fundamentally solves the problem of easy failure of traditional sealing rings under high pressure, high temperature, and corrosive water flow impact through a multi-layer synergistic structure design. Its main improvements are reflected in the following two aspects: On the one hand, in terms of the structural design of the sealing ring, the present invention opens an annular groove on the side of the first ring body that contacts the high-pressure area, and builds a buffer member formed by alternating metal layers and elastic layers wrapping the second ring body. The buffer member is pressed tightly with the outer pressure ring and the inner pressure ring through the protruding positioning part of the buffer member, so that the buffer member is compressed in a controllable manner when subjected to water flow impact, which can absorb impact energy and avoid the metal ring body being directly stressed.

[0014] On the other hand, in terms of the design of the protective coating, the present invention adopts a gradient protective coating. A gradient coating with decreasing thermal expansion coefficient and increasing Cr content is set on the high-pressure side contact surface of the sealing ring. The gradient transition of thermal expansion coefficient suppresses interlayer stress, while the high hardness surface with high Cr content on the outer layer reduces water flow friction.

[0015] The present invention provides a sealing ring for a high-temperature condensate pump. The structure and coating are optimized for the characteristics of the high-pressure area of ​​the condensate pump, forming a multi-protection mechanism including elastic buffering, mechanical fixation and corrosion protection. The sealing ring achieves a synergistic improvement in impact resistance, high-temperature stability and corrosion resistance, making it better meet the application requirements of high-parameter condensate pump systems in thermal power plants / nuclear power plants.

[0016] Furthermore, the first ring is made of Inconel 718 alloy. Inconel 718 alloy is a precipitation-hardening nickel-chromium-iron alloy containing niobium and molybdenum. Its composition is mainly nickel, chromium, and iron, with added elements such as niobium and molybdenum. It exhibits stable chemical properties and oxidation resistance within a temperature range of -250℃ to 1000℃, and maintains high strength, corrosion resistance, and toughness, especially at 700℃. This invention uses Inconel 718 alloy as the material for the first ring to ensure that the first ring can withstand high temperatures and possesses high strength and corrosion resistance.

[0017] Furthermore, the second ring body, serving as the supporting skeleton of the buffer, and the outer and inner pressure rings, serving as components that restrict the buffer, are both made of materials with high strength, high temperature resistance, and corrosion resistance. Preferably, the second ring body is made of Inconel 625 alloy, and the outer and inner pressure rings are made of Waspaly alloy.

[0018] Furthermore, the positioning part gradually narrows outward from the annular groove, and its cross-section is trapezoidal; the inclination angles of the sidewalls of the outer pressure ring and the inner pressure ring that contact the positioning part are respectively matched with the shape of the positioning part. Preferably, the inclination angle of the sidewalls of the positioning part is 40°-50°.

[0019] Furthermore, the outer surface of the second ring is covered with at least one metal layer and at least one elastic layer; when the sum of the number of the metal layer and the elastic layer is greater than two, the metal layer and the elastic layer are arranged alternately.

[0020] Furthermore, the metal layer is formed by winding 304 stainless steel wire; the elastic layer is formed by winding polytetrafluoroethylene wire. This invention employs a combination of a metal layer and an elastic layer to wind the second ring in layers, providing better elasticity and preventing the buffer from failing. Preferably, the thickness of the metal layer is 0.3±0.05mm, and the thickness of the elastic layer is 0.5±0.1mm.

[0021] Furthermore, the outer pressure ring and the inner pressure ring are fixedly connected to the first ring body by welding.

[0022] Furthermore, the coating comprises, from the inside out, an underlayer, a transition layer, and a functional layer; the underlayer is a NiCrAlY coating; the transition layer is a mixture of Cr2O3 and Al2O3; and the functional layer is a Cr2O3 coating. In this invention, the functional layer located on the coating surface is a Cr2O3 coating. Cr2O3 coatings possess chemical inertness and high mechanical strength and hardness, making them highly suitable for wear-resistant applications. This invention uses a Cr2O3 coating as the functional layer for both the sealing ring and the high-pressure side protective coating, achieving the purpose of resisting water flow abrasion and water flow erosion.

[0023] Furthermore, considering the significant difference in thermal expansion coefficients between the first ring-shaped substrate Inconel 718 alloy and the Cr2O3 coating, this invention adds a transition layer and a base coat between the functional layer of the coating and the first ring-shaped substrate. The base coat, NiCrAlY, is used to improve the bonding strength between the coating and the substrate; the transition layer is used to achieve a transition in composition and properties between the base coat and the functional layer. In this invention, the transition layer and base coat not only improve the bonding strength between the Inconel 718 alloy and the Cr2O3 coating through the gradient distribution of Cr, but also, because the thermal expansion coefficient of the transition layer Cr2O3-Al2O3 hybrid coating is between that of the base coat NiCrAlY coating and the functional layer Cr2O3 coating, it also reduces the risk of peeling off due to thermal changes.

[0024] Preferably, the underlying NiCrAlY coating has the following composition by mass percentage: Cr 18-22%, Al 5-8%, Y 0.3-1.0%, with the balance being Ni and unavoidable impurities.

[0025] Preferably, in the transition layer Cr2O3-Al2O3 mixed coating, the mass ratio of Cr2O3 to Al2O3 is (2.5-3.5):(1.5-2.5).

[0026] Preferably, the Cr2O3 coating of the functional layer has a purity of ≥99.5%, a grain size of 1-5 μm, and a microtexture structure with a depth of 5-15 μm on its surface. This microtexture structure, based on hydrodynamic optimization and interface effect control, reduces friction between the water flow and the functional layer, thereby improving the service life of the functional layer.

[0027] Preferably, the microtexture structure of the functional layer adopts an array of rhombic micro-pits, with a side length of 40-60 μm and a depth of 8-12 μm. The density of rhombic micro-pits on the surface of the functional layer (i.e., the percentage of the area of ​​rhombic micro-pits to the area of ​​the functional layer) is set to 15% to 20%, and the rhombic micro-pits are obtained by laser processing. More preferably, the rhombic micro-pits are filled with a solid lubricant, including MoS2 solid lubricant, etc.

[0028] Furthermore, the thickness of the underlayer is 70-100 μm; the thickness of the transition layer is 40-60 μm; and the thickness of the functional layer is 90-140 μm. The underlayer thickness of ≥70 μm ensures sufficient bonding strength and thermal stress buffering capacity, while avoiding a decrease in toughness due to excessive thickness. The 40-60 μm thickness of the transition layer effectively achieves a gradient transition of Cr2O3 / Al2O3 composition, ensuring a matching coefficient of thermal expansion. The functional layer thickness is controlled at 90-140 μm, providing excellent wear and corrosion resistance while preventing residual stress accumulation caused by excessive thickness. Compared to conventional coating solutions, the coating with the above thickness combination significantly improves the service life of the coating under high pressure and high temperature conditions.

[0029] The second objective of this invention is to provide a method for manufacturing a sealing ring for a high-temperature hydrophobic pump, as described in one objective of this invention, comprising the following steps: S1. An annular groove is formed on the first annular body; S2. Press the buffer into the annular groove; S3. Install the outer pressure ring and the inner pressure ring, and fix the outer pressure ring and the inner pressure ring to the first ring body by laser welding; S4. Apply a coating to the outer pressure ring, inner pressure ring, and the area on the first end face that is in contact with the high-pressure zone.

[0030] Furthermore, in step S4, the coating is applied using a high-velocity oxygen fuel (HVOF) spraying process, which offers advantages such as high coating density, low heat input, and strong adhesion. This invention uses HVOF spraying to prepare gradient coatings: for the undercoat, the antioxidant activity of Al / Y elements in the powder is preserved, forming a dense metallic bonding layer; for the functional layers, high-speed particle impact refines the Cr2O3 grains, increasing surface hardness. The dense coating prepared by the HVOF spraying process can resist the impact of high-pressure water flow cavitation collapse, while its low porosity effectively inhibits coating peeling caused by high-temperature water vapor penetration.

[0031] Further, in step S4, the coating covers the area where the outer pressure ring contacts the high-pressure area, the area where the inner pressure ring contacts the high-pressure area, and the area where the first end face contacts the high-pressure area. No coating is applied to the surface of the buffer component; before coating is applied, a heat-insulating and high-temperature-resistant shielding material is placed on the surface of the buffer component to protect it.

[0032] The third objective of this invention is to provide a high-temperature condensate pump for a thermal power plant, wherein a sealing ring as described in one objective of this invention is installed at the junction of the pump casing inner end and the outer edge of the impeller protrusion.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In the sealing ring of a high-temperature condensate pump provided by the present invention, the first ring body is used for sealing between the pump body and the impeller of the condensate pump. By placing a buffer in the annular groove of the end face of the first ring body facing the high-pressure area to withstand the impact of water flow in the pump body, the energy absorption of the buffer is utilized to reduce the impact intensity of water flow on the first ring body, thereby improving the overall impact resistance of the sealing ring. In addition, the outer pressure ring and the inner pressure ring cooperate with the positioning part of the protruding buffer to firmly press the buffer into the annular groove, preventing the buffer from falling out of the annular groove. The coating covering the surface of the first end face, the outer pressure ring and the inner pressure ring in contact with the high-pressure area adopts a dual gradient design of Cr element content and thermal expansion coefficient to protect the end face of the sealing ring facing the high-pressure area and improve its corrosion resistance.

[0034] (2) The present invention provides a method for manufacturing a sealing ring for a high-temperature condensate pump. A gradient coating with low porosity and high hardness is prepared using an HVOF spraying process. The friction coefficient between the functional layer surface and the water flow is reduced through laser processing of diamond-shaped micro-pits and a solid lubricant filling process. The overall manufacturing process of the sealing ring provided by the present invention can achieve fully automated production, resulting in good product consistency. Compared with traditional sealing rings, the prepared sealing ring has superior overall impact resistance and a longer service life, better meeting the application requirements of high-temperature condensate pumps in thermal power plants. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the sealing ring structure of the high-temperature hydrophobic pump provided in Embodiment 1 of the present invention; Figure 2 for Figure 1 Enlarged view of a portion of point A in the middle; Figure 3 for Figure 2 Enlarged view of a section at point B in the middle; Figure 4 This is a partial enlarged view of point A of the sealing ring structure of the high-temperature condensate pump provided in Embodiment 2 of the present invention; Wherein, 1-first ring body; 11-annular groove; 2-buffer; 21-positioning part; 22-second ring body; 23-metal layer; 24-elastic layer; 3-outer pressure ring; 4-inner pressure ring; 5-coating; 51-undercoat layer; 52-transition layer; 53-functional layer; 6-pump body; 7-impeller; 8-high pressure zone; 9-low pressure zone. Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0038] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0039] Example 1 Please see Figure 1-3 This embodiment provides a sealing ring for a high-temperature condensate pump, which is disposed between the pump body 6 and the impeller 7. The sealing ring includes: a first ring body 1, a buffer 2, an outer pressure ring 3, an inner pressure ring 4, and a coating 5.

[0040] The first ring body 1 is made of Inconel 718 alloy, and the outer diameter of the first ring body 1 is a fixed value (that is, the outer diameter of the first ring body 1 remains the same from the low pressure zone 9 to the high pressure zone 8). The first ring body 1 is fixed with the pump body 6 by interference fit. An annular groove 11 is formed on the first end face of the first ring body 1 adjacent to the high-pressure zone 8; a buffer member 2 is disposed in the annular groove 11, and the buffer member 2 protrudes outward from the annular groove 11 to form a positioning part 21; the positioning part 21 gradually narrows outward from the annular groove 11 with an inclination angle of 45°; its cross-section is trapezoidal; the buffer member 2 includes a second ring body 22, and a covering layer formed by alternating metal layer 23 and elastic layer 24 covering the outer surface of the second ring body 22; an outer pressure ring 3 and an inner pressure ring 4 are coaxially disposed on the first ring body 1, and the inclination angles of the sidewalls of the outer pressure ring 3 and the inner pressure ring 4 that contact the positioning part 21 are respectively matched with the shape of the positioning part 21, and the two abut against the outer sidewall and the inner sidewall of the positioning part 21 respectively to press and fix the buffer member 2. A coating 5 covers the outer pressure ring 3, the inner pressure ring 4 and the area of ​​the first end face that contacts the high-pressure zone; the coefficient of thermal expansion of the coating 5 decreases from the inside to the outside and the Cr content increases.

[0041] The sealing ring of the high-temperature condensate pump provided in this embodiment uses a first ring body for sealing between the pump body and the impeller; a buffer member is provided on the end face of the first ring body facing the high-pressure area to withstand the impact of water flow in the pump body. The buffer member compresses and absorbs energy, reducing the impact intensity of the water flow on the first ring body, thereby improving the overall impact resistance of the sealing ring; the buffer member is pressed against the annular groove by the outer pressure ring and the inner pressure ring to prevent the buffer member from falling out of the annular groove; and a coating is provided to protect the end face of the sealing ring facing the high-pressure area, thereby improving the corrosion resistance of the sealing ring.

[0042] The sealing ring of the high-temperature condensate pump provided in this embodiment has been optimized in structure and coating for the characteristics of the high-pressure area of ​​the condensate pump, forming a multi-protection mechanism including elastic buffering, mechanical fixation and corrosion protection. It achieves a synergistic improvement in impact resistance, high-temperature stability and corrosion resistance in a single sealing ring, making it better meet the application requirements of high-parameter condensate pump systems in thermal power plants / nuclear power plants.

[0043] Example 2 like Figure 4 As shown, this embodiment provides another sealing ring for a high-temperature condensate pump. The main difference between this and embodiment 1 is that the outer diameter of the first ring body 1 gradually increases along the direction from the low-pressure zone 9 to the high-pressure zone 8, and the tilt angle is 15°.

[0044] In this embodiment, the pressure difference between the high-pressure zone 8 and the low-pressure zone 9 is used to continuously press the first ring 1 and the pump body 6 together; at the same time, based on the existence of the above pressure difference, it is ensured that under the premise of temperature changes and thermal expansion and contraction between the pump housing and the sealing ring, a certain fit clearance is always maintained between the pump housing and the sealing ring to avoid loosening.

[0045] Example 3 Based on Embodiment 1 or 2, this embodiment further designs the structure of the buffer 2: the outer surface of the second ring 22 is sequentially covered with a first metal layer, a first elastic layer, a second metal layer, and a second elastic layer. The first and second metal layers are formed by winding 304 stainless steel wire, with thicknesses of 0.3±0.05mm respectively; the first and second elastic layers are formed by winding polytetrafluoroethylene wire, with thicknesses of 0.5±0.1mm respectively.

[0046] In this embodiment, the outer surface of the second ring 22 is alternately wrapped with a metal layer 23 and an elastic layer 24 to form a buffer 2. At the same time, the protruding positioning part 21 of the buffer 2 is pressed tightly with the outer pressure ring 3 and the inner pressure ring 4, so that the buffer 2 is compressed in a controllable manner when subjected to water flow impact. This can absorb the impact energy and prevent the second ring 22 from being directly subjected to force, thus ensuring the reliability of the seal.

[0047] Example 4 This embodiment, based on Embodiment 3, optimizes the design of coating 5: coating 5 comprises, from the inside out, a base layer 51, a transition layer 52, and a functional layer 53. The base layer 51 is a NiCrAlY coating (by weight percentage: Ni 73.5 wt%, Cr 20 wt%, Al 6 wt%, Y 0.5 wt%), with a thickness of approximately 80 μm and a coefficient of thermal expansion of approximately 12.5 × 10⁻⁶. -6 / ℃; the transition layer 52 is composed of Cr2O3 and Al2O3 in a 3:2 mass ratio, with a thickness of approximately 55μm and a coefficient of thermal expansion of approximately 8.3×10.-6 / ℃; the functional layer 53 is a Cr2O3 coating with a thickness of approximately 120 μm and a coefficient of thermal expansion of approximately 7.5 × 10⁻⁶. -6 / ℃.

[0048] Furthermore, the surface of the functional layer 53 is provided with a microtexture structure composed of an array of rhomboid micro-pits. The area of ​​the rhomboid micro-pits accounts for 18% of the area of ​​the functional layer. The side length of the rhomboid micro-pits is 50μm and the depth is 10μm. They are obtained by laser processing and are filled with MoS2 solid lubricant.

[0049] In this embodiment, a gradient protective coating is adopted. A gradient coating with decreasing thermal expansion coefficient and increasing Cr content is set on the high-pressure side contact surface of the sealing ring. The interlayer stress is suppressed by the gradient transition of thermal expansion coefficient. At the same time, the high-hardness surface with high Cr content and micro-texture structure of the outer layer are used to reduce water flow friction, which fundamentally solves the problem of easy failure of traditional sealing rings under high pressure, high temperature and corrosive water flow impact.

[0050] Example 5 This embodiment provides a method for manufacturing the sealing ring of the high-temperature hydrophobic pump described in Embodiment 4, including the following steps: Step 1: Open an annular groove 11 on the end face of the first annular body 1 facing the high-voltage area; Step 2: Alternately wind metal wire and elastic wire around the second ring 22 to form a buffer 2, press the buffer 2 into the annular groove 11, and make the positioning part 21 protrude out of the annular groove 11. Step 3: Install the outer pressure ring 3 and the inner pressure ring 4, and fix the outer pressure ring 3 and the inner pressure ring 4 to the first ring body 1 by laser welding; Step 4: Spray coating 5 on the outer pressure ring 3, inner pressure ring 4 and the area where the first end face contacts the high-pressure area; the spraying adopts HVOF spraying process, first preheat the substrate to 150~200℃, and then deposit the base layer, transition layer and functional layer in sequence. Step 5: A diamond-shaped micro-pit array is formed on the surface of the functional layer using laser processing, and MoS2 solid lubricant is filled into the diamond-shaped micro-pits to complete the manufacturing process of the sealing ring.

[0051] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. A sealing ring for a high-temperature condensate pump, disposed between the pump body and the impeller, characterized in that, The sealing ring includes: The first annular body (1) has an annular groove (11) on its first end face adjacent to the high voltage zone. A buffer (2) is disposed in an annular groove (11), and the buffer (2) protrudes outward toward the annular groove (11) to form a positioning part (21); the buffer (2) includes a second ring body (22) and a covering layer formed by alternating metal layer (23) and elastic layer (24) covering the outer surface of the second ring body (22); The outer pressure ring (3) and the inner pressure ring (4) are coaxially arranged on the first ring body (1) and respectively abut against the outer side wall and inner side wall of the positioning part (21) to press and fix the buffer (2); The coating (5) covers the outer pressure ring (3), the inner pressure ring (4) and the area where the first end face contacts the high pressure zone; the coefficient of thermal expansion of the coating (5) decreases from the inside to the outside and the content of Cr element increases.

2. The sealing ring of the high-temperature hydrophobic pump according to claim 1, characterized in that, The first ring body (1) is made of Inconel 718 alloy.

3. The sealing ring of the high-temperature hydrophobic pump according to claim 1, characterized in that, The positioning part (21) gradually narrows outward from the annular groove (11), and its cross-section is trapezoidal; the inclination angles of the sidewalls of the outer pressure ring (3) and the inner pressure ring (4) that contact the positioning part (21) are respectively matched with the shape of the positioning part (21).

4. The sealing ring of the high-temperature hydrophobic pump according to claim 1, characterized in that, The outer surface of the second ring (22) is covered with at least one metal layer (23) and at least one elastic layer (24); when the sum of the number of metal layers (23) and elastic layers (24) is greater than 2, the metal layers (23) and elastic layers (24) are arranged alternately.

5. The sealing ring of the high-temperature hydrophobic pump according to claim 1, characterized in that, The metal layer (23) is formed by winding 304 stainless steel wire; the elastic layer (24) is formed by winding polytetrafluoroethylene wire.

6. The sealing ring of the high-temperature hydrophobic pump according to claim 1, characterized in that, The coating (5) consists of an underlayer (51), a transition layer (52), and a functional layer (53) from the inside out; the underlayer (51) is a NiCrAlY coating; the transition layer (52) is a mixture of Cr2O3 and Al2O3; and the functional layer (53) is a Cr2O3 coating.

7. The sealing ring of the high-temperature hydrophobic pump according to claim 6, characterized in that, The surface of the functional layer (53) is provided with a microtexture structure of a diamond-shaped micro-dimple array, and the density of the microtexture structure accounts for 15%-20% of the area of ​​the functional layer (53).

8. The sealing ring of the high-temperature hydrophobic pump according to claim 6, characterized in that, The thickness of the base layer (51) is 70-100 μm; the thickness of the transition layer (52) is 40-60 μm; and the thickness of the functional layer (53) is 90-140 μm.

9. A method for manufacturing the sealing ring of a high-temperature condensate pump according to any one of claims 1-8, characterized in that, Includes the following steps: S1. An annular groove (11) is opened on the first annular body (1). S2. Press the buffer (2) into the annular groove (11); S3. Install the outer pressure ring (3) and the inner pressure ring (4), and fix the outer pressure ring (3) and the inner pressure ring (4) to the first ring body (1) by laser welding; S4. Apply a coating (5) to the outer pressure ring (3), the inner pressure ring (4) and the area where the first end face contacts the high-pressure zone.

10. A high-temperature condensate pump for a thermal power plant, characterized in that, The high-temperature condensate pump has a sealing ring installed at the junction of the pump casing inner source and the impeller protrusion outer edge, according to any one of claims 1-8.

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