A high-efficiency, long-life filter screen for a soft drink system

Abstract

This invention relates to a high-efficiency, long-life filter screen for a steam-water system, belonging to the field of steam-water separation and filtration technology. It includes: a support frame, which is a cylindrical structure with mounting flanges at both ends; reinforcing ribs distributed along the axial and circumferential directions of the support frame surface to form a mesh-like reinforcing structure; a filter layer disposed inside the support frame; a flow rectifier located at the fluid inlet end of the support frame, the flow rectifier having multiple circumferentially distributed guide vanes for rectifying the steam-water two-phase flow entering the filter screen; and an anti-rush shield covering the inlet side of the flow rectifier, the anti-rush shield having multiple evenly distributed rectification holes.

Description

Technical Field

[0001] This invention belongs to the field of steam-water separation and filtration technology, and specifically relates to a high-efficiency, long-life filter screen for steam-water systems. Background Technology

[0002] In the steam-water systems of thermal power plants and nuclear power plants, steam carries condensed water droplets during pipeline transportation and operation. Simultaneously, the system also contains solid impurities such as pipeline corrosion products, oxide scale, and welding slag. If these impurities enter the turbine with the steam, they can cause high-speed erosion of the turbine blades, resulting in blade damage, reduced efficiency, and in severe cases, blade breakage. Filter screens, as key purification components in the steam-water system, are installed in main steam pipelines, reheat steam pipelines, and turbine inlets to filter out solid particles and large-diameter water droplets entrained in the steam, protecting the safe operation of critical equipment such as the turbine. Due to the high steam velocity (up to 30-50 m / s) and high temperature (up to over 550℃) in the steam-water system, as well as the erosion caused by two-phase steam-water flow, extremely high requirements are placed on the strength, wear resistance, filtration accuracy, and service life of the filter screen. A single-layer stainless steel wire mesh is used as the filter element, fixed inside the pipeline by a support ring.

[0003] Currently, most steam-water systems use single-layer woven metal mesh or perforated plate filters. In actual operation, ordinary woven mesh is prone to wear and breakage under long-term erosion from high-speed steam-water two-phase flow, especially at the cross-welding points where stress concentration and erosion damage easily occur. Simultaneously, single-layer mesh has low filtration accuracy, allowing fine impurities to easily penetrate and become embedded in the mesh, causing blockage and increasing the pressure difference across the filter. Furthermore, steam at the filter inlet directly impacts the center of the filter, resulting in severe localized erosion. The overall rigidity of the filter is poor, making it susceptible to deformation or even damage under high-speed steam flow. Currently, most soft drink systems use single-layer woven metal mesh or perforated plate filters.

[0004] The existing technology has at least the following problems during use: ordinary filter screens in the steam-water system have poor erosion resistance, are easy to clog, and have insufficient overall rigidity. Under the long-term action of high-speed steam-water two-phase flow, the screen is prone to damage, the filtration accuracy is unstable, the service life is short, and frequent replacement affects the availability of the unit. Summary of the Invention

[0005] This invention provides a high-efficiency, long-life filter screen for a steam-water system, which solves the technical problems of existing steam-water system filter screens having poor erosion resistance, easy clogging, insufficient rigidity, easy damage under high-speed steam-water two-phase flow, and short service life.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-efficiency, long-life filter screen for a steam-water system, comprising: a support frame, the support frame being a cylindrical structure, with mounting flanges at both ends of the support frame; reinforcing ribs distributed along the axial and circumferential directions on the surface of the support frame, forming a mesh-like reinforcing structure; a filter layer disposed inside the support frame; a rectifier protector disposed at the fluid inlet end of the support frame, the rectifier protector having multiple circumferentially distributed guide vanes for rectifying the steam-water two-phase flow entering the filter screen; and an anti-rush cover covering the inlet side of the rectifier protector, the anti-rush cover having multiple evenly distributed rectification holes.

[0007] Furthermore, the reinforcing rib assembly includes axial reinforcing ribs and circumferential reinforcing rings. A plurality of axial reinforcing ribs are evenly distributed circumferentially along the support frame, and a plurality of circumferential reinforcing rings are spaced apart axially along the support frame. The axial reinforcing ribs and the circumferential reinforcing rings are welded to form an integral grid frame.

[0008] Furthermore, the filter layer includes a primary filter layer and a secondary filter layer. The primary filter layer is formed by continuously winding stainless steel wire around the inner surface of the first filter section of the supporting frame and fixing it by welding. The width of the first filter slit formed by the primary filter layer is 0.5-1mm.

[0009] Furthermore, the secondary filter layer comprises at least three layers of sintered stainless steel wire mesh, namely a support layer, a filter layer, and a protective layer. The filtration accuracy of the filter layer is 50-100μm. The mesh openings of adjacent wire mesh layers are staggered and stacked. The secondary filter layer is integrated with the inner surface of the second filter section of the support frame by vacuum diffusion sintering.

[0010] Furthermore, the guide vanes are streamlined vanes, and multiple guide vanes are spirally distributed along the central axis of the rectifier. The inlet angle of the guide vanes is 30°-45° and the outlet angle is 15°-20°, so that the gas-water two-phase flow entering the filter screen generates a circumferential swirling flow.

[0011] Furthermore, the anti-impact shield has a hemispherical or conical structure, and the rectifier holes are evenly distributed along the surface of the anti-impact shield, with a diameter of 5-8 mm.

[0012] Furthermore, the fluid outlet end of the supporting frame is also provided with a vortex disperser, which has multiple radially distributed rectifiers to eliminate swirling flow at the filter outlet and make the fluid flow out evenly.

[0013] This invention provides a high-efficiency, long-life filter screen for soft drink systems, with the following advantages: The cylindrical support frame, combined with the reinforcing ribs welded into a grid, provides all-round rigid support for the internal filter layer, which greatly improves the overall pressure difference resistance and airflow impact deformation resistance of the filter, and avoids the filter layer from being damaged by pressure. Through the gradient composite built-in structure of primary and secondary filter layers, large particles of impurities are intercepted by the primary filter layer, while small particles are finely intercepted by the sintered wire mesh secondary filter layer, which takes into account both high flow capacity and stable filtration accuracy. The 0.5-1mm gradually expanding first filter gap can reduce impurity clogging and improve backwash recovery performance. By using an inlet hemispherical / conical anti-impact cover in conjunction with a spiral streamlined guide vane, the steam and water are first buffered and diverted through the rectifier hole, and then the spiral vane generates a circumferential vortex. Centrifugal force is used to separate large water droplets and large particle impurities, avoiding high-speed steam and water from concentrating and eroding the central area of ​​the filter screen, thus reducing the wear of the filter layer. The radial rectifier plate of the outlet vortex disperser eliminates fluid swirl, balances the flow field at the filter outlet, reduces pipeline flow resistance, and avoids swirl impact on downstream thermal equipment. The overall structure is erosion resistant, not easy to clog, and has stable filtration accuracy over a long period of time. Compared with ordinary single-layer woven filter screens, its service life is significantly improved, making it suitable for long-term continuous operation of high-temperature and high-pressure steam and water systems. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the structure of a high-efficiency, long-life filter screen for a soft drink system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the reinforcing rib assembly for a high-efficiency, long-life filter screen used in a soft drink system, provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the rectifier plate provided in an embodiment of the present invention; Figure 4 A schematic diagram of the flow divider provided in an embodiment of the present invention; Figure 5 A schematic diagram of the flow divider mechanism provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the anti-impact shield provided in an embodiment of the present invention; Figure 7 This is a top view of the anti-impact shield provided in an embodiment of the present invention; Figure 8This is a cross-sectional view of a high-efficiency, long-life filter screen for a soft drink system provided in an embodiment of the present invention.

[0016] In the diagram: 11-Support frame; 12-Mounting flange; 21-Axial reinforcing rib; 22-Circumferential reinforcing ring; 3-Primary filter layer; 4-Secondary filter layer; 51-Rectifier protector; 52-Guide vane; 53-Split plate; 54-Split seat; 55-Arc groove; 56-Rotating grid plate; 57-Drive rod; 58-Actuating rod; 61-Anti-impact cover; 62-Rectifier hole; 71-Edge diffuser; 72-Rectifier plate. Detailed Implementation

[0017] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0018] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application 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. Therefore, they should not be construed as limitations on this application.

[0019] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to welding, bolting, or riveting; they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0021] Example: like Figures 1 to 7As shown, this embodiment provides a high-efficiency, long-life filter screen for a steam-water system, comprising: a support frame 11, which is a cylindrical structure, with mounting flanges 12 at both ends of the support frame 11; a reinforcing rib assembly, distributed along the axial and circumferential directions on the surface of the support frame 11 to form a mesh-like reinforcing structure; a filter layer, disposed inside the support frame 11, comprising a primary filter layer 3 and a secondary filter layer 4 [A1]; a rectifier protector 51, disposed at the fluid inlet end of the support frame 11, the rectifier protector 51 having multiple circumferentially distributed guide vanes 52 for rectifying the steam-water two-phase flow entering the filter screen; and an anti-rush cover 61, covering the inlet side of the rectifier protector 51, the anti-rush cover 61 having multiple evenly distributed rectification holes 62.

[0022] In this embodiment, the filter screen is a cylindrical structure, which is locked inside the filter screen seat of the steam-water pipeline by flanges 12 at both ends. The high-temperature steam-water two-phase flow flows in from the central inlet of the filter screen and penetrates the filter layer from the inside of the cylinder to the outside to complete the interception of impurities. The filtered clean steam-water flows out from the outside of the cylinder. The support frame 11 serves as the load-bearing base of the whole machine and bears the high-speed impact of steam-water and the system pressure difference load. The reinforcing rib assembly forms a grid support on the outer wall of the frame to share the fluid pressure borne by the filter layer and prevent the cylinder wall from deforming. The built-in gradient filter layer realizes graded interception. Large particles of oxide scale and water droplets are intercepted by the primary filter layer 3, and fine dust particles are filtered by the secondary sintered wire mesh. The integrated anti-impact and rectification structure at the inlet buffers the high-speed incoming flow, evenly distributes the flow field inside the cylinder, and avoids local erosion damage to the filter layer.

[0023] Furthermore, the support frame 11 is made of stainless steel perforated plate rolled and welded, the opening ratio of the support frame 11 is not less than 60%, the opening diameter of the support frame 11 is 8-12mm, and the mounting flange 12 is welded to the support frame 11 to form an integral structure.

[0024] In this embodiment, a flow divider 53 can also be provided in the mounting flange 12. The flow divider 53 is a tapered strip used to directly impact and disperse the fluid to be filtered. A flow divider seat 54 can also be provided in the mounting flange. The flow divider seat 54 is provided with a mounting ring with an arc groove 55. The mounting ring is provided with a fixed rotating groove and a mounting interlayer. A wave rod 58 is provided on the side wall of the mounting ring. The side wall of the mounting seat is provided with a slot. The actuating rod slides in the slot of the side wall to drive the mounting ring to rotate. The rotating grid plate is a tapered or triangular blade with a rotating shaft installed in the rotating groove. A drive rod 57 is also provided. The drive rod 57 is slidably disposed in the arc groove 55. The sliding actuating rod 58. Multiple rotating grid plates 56 are driven to rotate on one side by the sliding of the drive rod 57 along the arc groove 55, thereby connecting multiple rotating grid plates 56 to change the diameter of the through holes, thereby realizing flow control to reduce losses. Correspondingly, a mechanical limit and sealing structure for locking pins is set. The support frame 11 is made of 316L stainless steel plate with a thickness of 3-5mm. The plate surface is stamped with evenly distributed flow holes, rolled into a cylinder and then longitudinally beveled and welded. The two ends of the cylinder are welded together with the thickened mounting flange 12. The high opening ratio of more than 60% ensures the flow area and reduces the filter flow resistance. The 3-5mm thick base material provides basic rigidity and can withstand the operating pressure difference of more than 0.3MPa for a long time without plastic deformation.

[0025] Furthermore, the reinforcing rib assembly includes axial reinforcing ribs 21 and circumferential reinforcing rings 22. Multiple axial reinforcing ribs 21 are evenly distributed circumferentially along the support frame 11, and multiple circumferential reinforcing rings 22 are spaced apart axially along the support frame 11. The axial reinforcing ribs 21 and circumferential reinforcing rings 22 are welded to form an integral grid frame.

[0026] In this embodiment, the axial reinforcing ribs 21 are made of 6×6mm stainless steel square steel, with one rib arranged every 30° along the circumference of the cylinder, for a total of 12 ribs; the circumferential reinforcing rings 22 are made of 5×20mm stainless steel flat steel, with one ring arranged every 100mm along the axial direction of the cylinder, and the intersection of the ribs and rings is fully welded to form a grid support unit with a size of approximately 100×30mm; the grid structure divides the cylinder wall into multiple independent pressure-bearing areas, improving the cylinder's resistance to deformation, and preventing large-scale spread and failure of local filter layer damage.

[0027] Furthermore, the filter layer includes a primary filter layer 3 and a secondary filter layer 4. The primary filter layer 3 is formed by continuously winding stainless steel wire around the inner surface of the first filter section of the support frame 11 and fixing it by welding. The width of the first filter slit formed by the primary filter layer 3 is 0.5-1mm.

[0028] In this embodiment, the primary filter layer 3 is made of 316L wedge-shaped stainless steel wire continuously wound. The cross-section of the wedge-shaped wire is trapezoidal, with the short side of the trapezoid facing the inside of the fluid flow. The wedge-shaped wire is tightly wound on the inner surface of the first filter section upstream of the support frame 11. Each turn of the wedge-shaped wire is spot-welded to the cylinder wall, and a 0.5~1mm gradually expanding first filter gap is formed between adjacent wedge-shaped wires. Large impurities are trapped inside the filter screen and will not be embedded deep in the filter gap. When the equipment is backwashed, the impurities can be quickly flushed out with the fluid, and the filter gap clogging cycle is greatly extended.

[0029] Furthermore, the secondary filter layer 4 comprises at least three layers of stainless steel wire mesh sintered together, namely a support layer, a filter layer and a protective layer. The filtration accuracy of the filter layer is 50-100μm. The mesh openings of adjacent wire mesh layers are staggered and stacked. The secondary filter layer 4 is integrated with the inner surface of the second filter section of the support frame 11 by vacuum diffusion sintering.

[0030] In this embodiment, the three layers of wire mesh in the secondary filter layer 4 are, from the inside out, a 20-mesh coarse support wire mesh, a 200-mesh precision filter wire mesh, and a 60-mesh protective wire mesh. After the three layers of wire mesh are interlaced and stacked, they are sent into a vacuum sintering furnace at 1300℃ to complete diffusion fusion, and the wire mesh contact points are fused together. Then, the whole structure is vacuum sintered and bonded to the inner surface of the second filter section downstream of the support frame 11. The interlaced mesh eliminates straight gaps, improves the interception efficiency of small particles, and the sintered integrated structure has no risk of delamination or detachment.

[0031] Furthermore, the guide vanes 52 are streamlined vanes, and multiple guide vanes 52 are spirally distributed along the central axis of the rectifier protector 51. The inlet angle of the guide vanes 52 is 30°-45° and the outlet angle is 15°-20°, so that the gas-water two-phase flow entering the filter screen generates a circumferential swirling flow.

[0032] In this embodiment, the rectifier protector 51 is equipped with a total of 8 streamlined guide vanes 52, which are integrally cast spirally along the central axis. After the steam and water pass through the vanes, they form a stable circumferential swirling flow. Relying on centrifugal force, large water droplets and large pieces of oxide scale in the fluid are thrown towards the inner wall of the cylinder and flow downstream along the cylinder wall, reducing the direct impact of solid particles on the surface of the filter layer. The swirling flow also achieves uniform flow distribution around the cylinder, eliminating local high-speed erosion areas.

[0033] Furthermore, the anti-impact shield 61 has a hemispherical or conical structure, and the rectifier holes 62 are evenly distributed along the surface of the anti-impact shield 61, with a diameter of 5-8 mm.

[0034] In this embodiment, the anti-impact cover 61 is made of hemispherical 316L stainless steel stamping and is welded and fixed to the front end of the rectifier 51 facing the incoming steam and water flow. The spherical surface is evenly opened with rectifier holes 62 with a diameter of 5~8mm. The axis of the rectifier hole 62 is inclined at an angle of 15°~30° with the central axis of the filter screen. The high-speed steam and water first pass through the rectifier hole 62 for diversion and buffering to avoid concentrated impact on the center of the filter screen. At the same time, the rectifier hole 62 can pre-intercept oversized impurities to prevent large hard objects from hitting the internal guide vanes 52 and the filter layer.

[0035] Furthermore, the fluid outlet end of the support frame 11 is also provided with a vortex disperser 71, which has multiple radially distributed rectifier plates 72 for eliminating the swirling flow at the filter outlet and making the fluid flow out evenly.

[0036] In this embodiment, the vortex disperser 71 adopts an integrally welded structure of a cross-shaped radial rectifier plate 72, which is fixed to the inner side of the outlet mounting flange 12. After the swirling steam and water pass through the radial rectifier plate 72, the circumferential rotation speed is completely canceled out, and it is converted into a uniform and stable axial outflow, avoiding swirling vibration of the downstream pipeline, and reducing the local flow resistance at the outlet.

[0037] As a preferred improvement in this embodiment, the inner surfaces of the primary filter layer 3 and the secondary filter layer 4 are both coated with a WC-Co hard alloy hardening layer. The hardening layer is prepared by supersonic flame spraying, with a coating thickness of 0.2~0.3mm and a surface hardness of not less than HRC65. A fluorosilane-modified nano-silica hydrophobic coating is added to the inner side of the filter layer, with a water contact angle of ≥150°, which has a superhydrophobic self-cleaning effect.

[0038] In this embodiment, the HVOF supersonic flame spraying of WC-12Co hard alloy coating has high bonding strength and is dense and non-porous, which can improve the filter layer's resistance to high-speed water droplet erosion and particle abrasion by more than 90%. The nano hydrophobic coating causes water droplets to roll off the filter gap surface in a spherical manner, making it less likely to form a water film that clogs the filter pores, reducing the rate of increase in filter operating pressure differential, and extending the online operation cycle.

[0039] In this embodiment, after the filter screen is processed as a whole, it undergoes a stabilization and stress-relief heat treatment to eliminate residual stress generated by welding, stamping, and sintering, and to prevent deformation of the cylinder under high-temperature steam and water conditions; all welding positions are ground and polished to eliminate stress sharp corners; and flanges 12 are installed at both ends with matching graphite metal spiral wound sealing gaskets, so that there is no steam and water short-circuit leakage after the pipeline is installed.

[0040] In summary, this invention significantly improves the overall rigidity and resistance to pressure differential deformation of the filter screen by using a cylindrical support frame 11 combined with a mesh welded reinforcing rib assembly. The built-in primary wedge wire filter layer + multi-layer sintered mesh secondary filter layer 4-gradient composite structure balances high flow capacity with stable and precise filtration. The gradually expanding filter slot structure is less prone to impurity clogging, resulting in good backwashing recovery. The front hemispherical anti-surge shield 61, combined with spiral streamlined guide vanes 52, buffers and diverts high-speed steam and water, generating centrifugal vortexes to separate large water droplets and particles, preventing localized erosion of the filter layer. The outlet vortex disperser 71 and radial rectifier 72 eliminate fluid vortexes, balancing the downstream flow field and reducing pipeline resistance. The preferred design incorporates a hard alloy anti-erosion coating and a nano-hydrophobic self-cleaning coating to further reduce wear and slow clogging. The overall structure boasts high strength, resistance to steam and water erosion, and consistently stable filtration accuracy, with a service life more than 5 times longer than ordinary single-layer woven filters. It is suitable for long-term filtration conditions in high-temperature and high-pressure steam and water systems of thermal power plants and nuclear power plants.

[0041] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope described in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high efficiency long life filter screen for steam and water systems, characterized by, include: The support frame (11) is a cylindrical structure, and the two ends of the support frame (11) are respectively provided with mounting flanges (12). The reinforcing rib assembly is distributed along the axial and circumferential directions of the support frame (11) on the surface of the support frame (11) to form a grid-like reinforcing structure; A filter layer is disposed inside the support frame (11); A rectifier (51) is provided at the fluid inlet end of the support frame (11). The rectifier (51) has multiple guide vanes (52) distributed circumferentially for rectifying the gas-water two-phase flow entering the filter screen. An anti-surge shield (61) is installed on the inlet side of the rectifier protector (51), and the anti-surge shield (61) has a plurality of evenly distributed rectifier holes (62).

2. The filter screen with high efficiency and long service life for steam-water system according to claim 1, characterized in that, The reinforcing rib assembly includes axial reinforcing ribs (21) and circumferential reinforcing rings (22). A plurality of axial reinforcing ribs (21) are evenly distributed circumferentially along the support frame (11), and a plurality of circumferential reinforcing rings (22) are spaced apart axially along the support frame (11). The axial reinforcing ribs (21) and the circumferential reinforcing rings (22) are welded to form an integral grid frame.

3. The filter screen of claim 3, wherein the filter screen is a high-efficiency long-life filter screen for a steam-water system. The filter layer includes a primary filter layer (3) and a secondary filter layer (4). The primary filter layer (3) is made of stainless steel wire continuously wound on the inner surface of the first filter section of the support frame (11) and fixed by welding. The width of the first filter slit is 0.5-1mm.

4. The filter screen of claim 4, wherein the filter screen is a high-efficiency long-life filter screen for a steam-water system. The secondary filter layer (4) is made of at least three layers of stainless steel wire mesh sintered together, namely a support layer, a filter layer and a protective layer. The filtration accuracy of the filter layer is 50-100μm. The mesh openings of adjacent wire mesh layers are interlaced and stacked. The secondary filter layer (4) is integrated with the inner surface of the second filter section of the support skeleton (11) by vacuum diffusion sintering.

5. A high-efficiency, long-life filter screen for a soft drink system according to claim 5, characterized in that, The guide vane (52) is a streamlined vane, and multiple guide vanes (52) are spirally distributed along the central axis of the rectifier (51). The inlet angle of the guide vane (52) is 30°-45° and the outlet angle is 15°-20°, so that the gas-water two-phase flow entering the filter screen generates a circumferential swirling flow.

6. A high-efficiency, long-life filter screen for a soft drink system according to claim 6, characterized in that, The anti-impact shield (61) has a hemispherical or conical structure, and the rectifier holes (62) are evenly distributed along the surface of the anti-impact shield (61). The diameter of the rectifier holes (62) is 5-8 mm.

7. A high-efficiency, long-life filter screen for a soft drink system according to claim 7, characterized in that, The fluid outlet end of the support frame (11) is also provided with a vortex disperser (71), which has multiple radially distributed rectifiers (72) to eliminate the swirling flow at the filter outlet and make the fluid flow out evenly.

Images