Efficient anti-impact plate

Abstract

The application discloses a kind of high efficiency anti-collision plate, belong to thermal power plant tubular steam-water heater protection component technical field, including integrally bending forming's anti-collision plate body, body is equipped with main anti-collision area and symmetrical bending area, main anti-collision area is set up installation mouth and is embedded replaceable plate, replaceable plate is locked and fixed by backplate and mounting bolt;Replaceable plate annular array arrangement stepped pressure relief hole, aperture gradually increases from inside to outside, center is set up and is opposite the buffer boss of heater steam inlet, and radial reinforcing rib is left in pressure relief hole, the present application is reduced by steam multistage throttling shunt to steam by stepped pressure relief hole, reduce anti-collision plate end steam flow scouring speed, uniform steam distribution outside tube bundle, improve heat exchange efficiency;Center boss disperses impact load and reduces equipment vibration, and rib enhances plate rigidity and inhibits fluid excitation.

Description

Technical Field

[0001] This invention belongs to the field of protection technology for tubular steam-water heat exchange heaters, specifically a high-efficiency anti-impact plate used inside tubular steam-water heat exchange heaters in thermal power plants. It solves the problem of excessively high steam velocity and scouring of heat exchange tube bundles caused by the small gap between the traditional anti-impact plate and the heater shell, thereby achieving uniform distribution of the steam flow field, protecting the heater tube bundles and improving the overall heat exchange efficiency. Background Technology

[0002] The tubular steam-water heat exchanger in the thermal system of a thermal power plant is a core auxiliary machine of the unit's regenerative cycle system. It relies on high-temperature and high-pressure superheated / saturated steam and forced convection of feedwater inside the pipe to complete heat transfer, directly affecting the unit's coal consumption and operational safety.

[0003] Currently, the standard anti-impact plates for heaters in the industry are generally simple structures made by bending a single piece of steel plate, which have four inherent defects: 1. Severe erosion and wear of the tube bundles lead to a high risk of equipment failure: Traditional anti-impact plates have narrow pre-reserved steam flow channels on their outer edges and the inner wall of the heater cylinder. After high-speed steam impacts the plate surface, it can only be concentrated and sprayed from the narrow gaps on both sides. The downstream tube bundle is subjected to the erosion, abrasion and cavitation effects of high-speed steam carrying impurity particles for a long time. The tube wall continues to thin, which makes it very easy for tube wall perforation and leakage and tube bundle breakage to occur. This not only frequently increases the workload of tube bundle replacement and maintenance, but also causes unplanned unit shutdowns, resulting in huge economic losses.

[0004] II. Uneven steam flow field distribution leads to low heat exchange efficiency: Steam overflows only from fixed points on both sides of the anti-impact plate, resulting in a large difference in the distribution of steam medium in the circumferential direction of the heater tube bundle. The heat exchange load in different areas of the tube bundle is severely unbalanced, the nominal effective heat exchange area of ​​the heat exchanger cannot be fully utilized, the heater terminal temperature difference increases, the unit's thermal economy deteriorates, and energy consumption is high.

[0005] Third, the maintenance and disassembly are difficult and the downtime costs are high: Conventional anti-impact plates are integrally welded and fixed structures. Once the front is repeatedly eroded by steam and cracks, deforms, or develops holes, it is necessary to use hot work to cut and remove the entire large plate, and then hoist a new plate and weld it into place. The maintenance process is complicated and the maintenance cycle is long, which significantly occupies the unit's valuable shutdown window.

[0006] IV. Poor adaptability to operating conditions, and insufficient vibration reduction and durability: The integrated anti-impact plate cannot adjust the diversion and pressure reduction parameters according to different loads, inlet steam pressures and flow conditions of the unit; the vertical impact of steam on the plate surface causes severe vibration, which can easily cause long-term alternating fatigue cracking of the internal tie rods and support plate welded joints of the heater; the plate has no reinforcing structure, and the dense openings result in insufficient rigidity, which can easily cause fluid-induced vibration cracks; the single coating has poor adhesion and is very easy to fall off and fail in high-temperature water vapor environment.

[0007] In summary, existing anti-impact plates have significant shortcomings in terms of flow distribution and equalization, impact and vibration reduction, modular maintenance, multi-condition adaptability, and long-term wear and corrosion resistance, and urgently require systematic structural optimization and improvement. Summary of the Invention

[0008] One technical problem to be solved This invention addresses the technical problem of small gaps between the anti-impact plate and the shell of some tubular steam and water heat exchange heaters used in existing thermal power plants, resulting in excessively high steam flow rates, which severely erodes the tube bundles at the ends of the anti-impact plate and reduces the lifespan of the tube bundles.

[0009] Two technical solutions To achieve the above objectives, the technical solution adopted by the present invention is as follows: A high-efficiency impact protection plate, comprising: The impact protection plate includes a main impact protection zone in the middle, and symmetrical bending zones on the left and right sides. The impact protection plate is a one-piece structure. The mounting opening is located on the front side wall of the anti-impact plate and penetrates the anti-impact plate. Replaceable plate, which is installed inside the mounting port; Pressure relief holes are located on the front sidewall of the replaceable plate and are arranged in a ring array.

[0010] Further limitations on the above technical solution: the length, width, and thickness of the replaceable plate are the same as the length, width, and thickness of the mounting port.

[0011] Further limitations on the above technical solution: a back plate is fixedly installed on the rear side of the replaceable plate, and the length and width of the back plate are both greater than the length and width of the replaceable plate.

[0012] Further details of the above technical solution: threaded holes penetrating the anti-impact plate are provided at the four corners of the main anti-impact zone, and mounting holes are provided at the four corners of the back plate. The mounting holes and threaded holes are set one-to-one, and mounting bolts are installed in the mounting holes and screwed into the threaded holes.

[0013] Further definition of the above technical solution: the pressure-reducing holes are arranged in a ring array of multiple groups, and the diameter of the pressure-reducing holes increases sequentially from the inside to the outside.

[0014] Further limitations on the above technical solution: the pressure relief hole is a stepped hole, and the larger diameter hole of the stepped hole is located on the side away from the back plate, while the smaller diameter hole of the pressure relief hole penetrates through the back plate.

[0015] Further limitations on the above technical solution: A boss is fixedly installed at the center of the replaceable plate, and the boss is directly opposite the steam inlet of the tubular steam and water heat exchanger.

[0016] Further limitations on the above technical solution: A hemispherical boss is fixedly installed at the center of the replaceable plate. The hemispherical boss is directly opposite the steam inlet of the heater. Compared with a flat or cylindrical boss, it can smoothly decompose the impact kinetic energy of the vertically incident high-speed steam and avoid stress concentration at sharp corners. The hemispherical boss bears the main frontal erosion load and is a wear-resistant and reinforced area.

[0017] A ring-shaped stress relief groove can be opened around the root of the hemispherical boss to release the local tensile stress on the plate surface caused by impact loads and block the path of fatigue cracks extending from the root of the boss to the periphery of the plate. Lightweight through holes can be opened inside the hemispherical boss to reduce the overall weight and reduce the risk of long-term pressure creep of fasteners.

[0018] Further details of the above technical solution: the surfaces of the impact protection plate, the replaceable plate and the back plate, as well as the holes therein, are all coated with a wear-resistant coating. The coating material is WC-Co tungsten carbide, and the coating thickness is 0.25-0.35mm.

[0019] Three beneficial effects Compared with the prior art, the present invention provides a high-efficiency anti-impact plate with the following beneficial effects: After impacting the heat exchange plate, most of the high-temperature steam flows parallel to the bending areas on both sides of the anti-impact plate, reducing the steam velocity in the side gaps. A small portion of the steam permeates evenly into the tube bundle area behind the anti-impact plate after being throttled and decelerated step by step through the annular array of stepped pressure-reducing holes, thus preventing high-speed steam from concentrating and scouring the tube bundle at the source. This multi-point dispersed steam outlet ensures uniform distribution of the steam medium around the tube bundle, making the heat exchange load of each tube bundle more consistent, fully utilizing the heat exchange area, and effectively improving the overall heat exchange efficiency of the heater.

[0020] The core impact-resistant component is an independent replaceable plate. When it is subjected to long-term steam erosion, wear and cracking, only four mounting bolts need to be removed to replace the replaceable plate individually, without disassembling the entire large impact-resistant plate, which greatly shortens the downtime for maintenance. Furthermore, the replaceable plates with different opening ratios and different aperture gradients can be replaced according to different steam pressure, flow and load conditions of the unit, so as to flexibly adjust the steam pressure reduction and diversion effect.

[0021] The central boss facing the steam inlet bears the impact of high-speed steam in the vertical direction, dispersing the single-point concentrated impact stress to the entire replaceable plate surface, eliminating local stress concentration in the center, weakening the overall vibration of the heater cylinder caused by fluid impact, effectively protecting the welded joints of the internal tie rods of the heater, and preventing fatigue cracking of the weld and media leakage caused by long-term alternating vibration.

[0022] The radial integrated ribs inside the pressure relief holes compensate for the reduced structural strength of the replaceable plate caused by the dense openings, improve the bending and vibration resistance of the plate, hinder the fluid excitation generated by steam vortex, delay the initiation and propagation of fatigue cracks in the plate, and extend the service life of the replaceable plate itself.

[0023] The entire component is coated with a WC-Co tungsten carbide wear-resistant coating, which is resistant to high-temperature and high-pressure steam erosion, water vapor oxidation corrosion, and wear from solid impurity particles in the medium. It is suitable for the long-term harsh operating conditions of power plant heaters, further extending the overhaul cycle of the entire anti-impact plate and reducing the frequency of equipment maintenance. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the non-installed replaceable plate structure of the present invention; Figure 3 This is a schematic diagram of the connection structure between the replaceable plate and the back plate of the present invention; Figure 4 This is a schematic diagram of the arrangement of the boss and replaceable plate of the present invention; Figure 5 This is a schematic diagram of the rib arrangement structure inside the pressure-reducing hole of the present invention.

[0025] Among them, 1. Main anti-impact zone; 2. Bending zone; 3. Replaceable plate; 4. Mounting port; 5. Threaded hole; 6. Back plate; 7. Mounting hole; 8. Mounting bolt; 9. Pressure relief hole; 10. Boss; 11. Rib. Detailed Implementation

[0026] The following is in conjunction with the appendix Figure 1-5 The present invention will be described in further detail below.

[0027] Example 1: This example discloses a high-efficiency anti-impact plate, which mainly solves the technical problem of small gap between the anti-impact plate and the shell of some tubular steam and water heat exchangers used in existing thermal power plants, resulting in excessively high steam flow velocity, severely eroding the tube bundle at the end of the anti-impact plate, and causing a reduction in the life of the tube bundle. Figure 1 , Figure 2 As shown, the specific structural settings are as follows: The impact protection plate includes a central main impact protection zone 1, and symmetrical bending zones 2 on the left and right sides. The impact protection plate is a one-piece structure. Installation port 4 is located on the front side wall of the anti-impact plate and penetrates the anti-impact plate; Replaceable plate 3 is installed in mounting port 4. The length, width and thickness of replaceable plate 3 are the same as those of mounting port 4. A back plate 6 is fixedly installed on the rear side of replaceable plate 3. The length and width of back plate 6 are greater than those of replaceable plate 3. Threaded holes 5 penetrating the anti-impact plate are opened at the four corners of the main anti-impact zone 1. Mounting holes 7 are opened at the four corners of back plate 6. The mounting holes 7 and threaded holes 5 are set one-to-one. Mounting bolts 8 are installed in the mounting holes 7 and are screwed into the threaded holes 5. Pressure reducing holes 9 are provided on the front side wall of the replaceable plate 3. The pressure reducing holes 9 are arranged in a ring array. The pressure reducing holes 9 are multiple sets of ring array holes, and the diameter of the pressure reducing holes 9 increases from the inside to the outside. The pressure reducing holes 9 are stepped holes, and the larger diameter holes of the stepped holes are located on the side away from the back plate 6. The smaller diameter holes of the pressure reducing holes 9 penetrate the back plate 6.

[0028] The working principle of this embodiment is as follows: When the power plant heater is working, high-temperature and high-pressure saturated steam is injected vertically forward from the steam inlet of the equipment, and first impacts the surface of the replaceable plate 3 embedded in the mounting port 4 of the main anti-impact zone 1.

[0029] The first steam is blocked by the front of the replaceable plate 3 and flows horizontally to the left and right sides along the main anti-impact zone 1. It slowly flows out through the channel between the two side bending zones 2 and the heater shell. Due to the increased flow path and the constraint of the flow cross section by the bending zone 2, the steam velocity of this part is greatly reduced, avoiding high-speed rushing out from the side and directly scouring the downstream heat exchange tube bundle. The second steam path passes through the multi-layered, ring-shaped stepped pressure-reducing holes 9 on the replaceable plate 3 to achieve multi-stage throttling and pressure reduction: the steam first enters the front large-diameter stepped section for expansion, speed reduction, and pressure stabilization, and then passes through the rear small-diameter channel through the back plate 6, flowing into the tube bundle area behind the anti-impact plate in a low-speed diffused state. The replaceable plate 3 has three layers of concentric ring-shaped stepped pressure-reducing holes 9, which are divided into an inner high-pressure zone, a middle medium-pressure zone, and an outer low-pressure zone from the center outward. The diameter of each ring hole group increases step by step, and the depth of the inner ring stepped hole is greater than that of the middle ring and then the outer ring, thus achieving multi-stage throttling and pressure reduction in the central strong impact area.

[0030] The present invention also provides a pressure-reducing hole 9 scheme, wherein a single pressure-reducing hole 9 is a bidirectional stepped composite hole: the steam-facing side is a large-diameter flow-expanding cone section (diffusion and deceleration), a middle cylindrical throttling section, and a back-steam side micro-diffusion section. The back-steam side micro-diffusion section extends into the buffer cavity between the back plate and the replaceable plate, forcing the steam to diffuse radially along 360°.

[0031] The stepped orifice flow-limiting structure avoids local steam surges that impact the tube bundle. The multiple annular evenly distributed openings allow steam to be uniformly released at various locations above the tube bundle, completely improving the problems of steam flow deviation and localized concentrated heat exchange around the tube bundle. On the one hand, it greatly reduces the erosion and wear of the tube bundle wall by high-speed steam flow, extending the service life of the tube bundle. On the other hand, the tube bundle is heated evenly, and the effective heat exchange area of ​​the heat exchanger is fully utilized, directly improving the overall heat exchange efficiency of the tubular steam-water heater.

[0032] When the replaceable plate 3 is damaged by erosion after long-term operation, simply unscrew the four mounting bolts 8 at the four corners, remove the back plate 6, and pull out the old replaceable plate 3. After replacing it with a new replaceable plate 3, tighten the mounting bolts 8 again to complete the maintenance. There is no need to disassemble the bulky overall anti-impact plate, making the maintenance operation simple and efficient.

[0033] Example 2: This example further optimizes the structure based on Example 1, improving the device's impact resistance, such as... Figure 1 , Figure 3 , Figure 4 and Figure 5 As shown, the specific optimized structure is as follows: A boss 10 is fixedly installed at the center of the replaceable plate 3. The boss 10 is directly opposite the steam inlet of the tubular steam and water heat exchanger. A rib 11 is fixed at the small diameter end of the inner cavity of the pressure reduction hole 9. The rib 11 is left when the pressure reduction hole 9 is opened, and the central axis of the rib 11 points to the center of the boss 10. The surfaces of the anti-impact plate, replaceable plate 3 and back plate 6, as well as the holes on them, are all sprayed with a wear-resistant coating. The coating material is WC-Co tungsten carbide, and the coating thickness is 0.25-0.35mm.

[0034] The working principle of this embodiment is as follows: When high-temperature, high-pressure steam impacts vertically from the steam inlet, it first strikes the frustum-shaped boss 10 at the center of the replaceable plate. The boss 10 absorbs all the concentrated impact kinetic energy, dispersing the huge single-point impact force evenly to the entire surface of the replaceable plate 3, effectively eliminating stress concentration at the center of the plate. After the impact load is dispersed, the low-frequency vibration of the equipment caused by steam impact is greatly reduced, the reciprocating alternating stress of the heater cylinder and internal tie rods is reduced, and cracking and leakage failures due to long-term vibration fatigue are prevented at the weld connecting the tie rod and the cylinder.

[0035] The radially arranged ribs 11 inside the pressure relief hole 9 serve as built-in reinforcing ribs, which compensate for the lack of overall rigidity of the replaceable plate after a large number of holes are opened, significantly improve the plate's resistance to bending and resonance, effectively suppress the fluid excitation induced by the vortex formed by steam in the channel, avoid fatigue cracks in the replaceable plate 3 under long-term alternating loads, and further extend the service life of the replaceable plate 3.

[0036] Each pressure-reducing hole 9 has a small-diameter inner cavity integrally formed radial ribs 11. All ribs 11 converge towards the central boss 10 of the replaceable plate. The cross-section of the ribs 11 is a streamlined arc structure, abandoning the right-angle cross-section, which greatly reduces the eddy current resistance when steam flows through the channel. This not only strengthens the structural strength of the plate after the hole is opened, but also suppresses fluid excitation noise and alternating vibration.

[0037] The WC-Co tungsten carbide hard alloy coating, which covers the entire area, has high hardness, is resistant to cavitation, particle erosion, and high-temperature water vapor corrosion. Under the harsh operating conditions of power plant heaters, which are characterized by high temperature, high pressure, humidity, and the presence of trace impurity particles, it continuously protects the entire anti-impact plate component from rapid wear and reduces the frequency of equipment replacement.

[0038] The core working logic of steam diversion and pressure reduction, uniform steam distribution, and modular replacement is consistent with that of Example 1. Replaceable plates with different opening specifications can be replaced according to different operating parameters of the unit, flexibly adapting to on-site conditions, and further improving the comprehensive protection and energy-saving efficiency.

Claims

1. A high-efficiency anti-impact plate, characterized in that, include: The impact protection plate includes a main impact protection zone in the middle, and symmetrical bending zones on the left and right sides. The impact protection plate is a one-piece structure. The mounting opening is located on the front side wall of the anti-impact plate and penetrates the anti-impact plate. Replaceable plate, which is installed inside the mounting port; Pressure relief holes are located on the front sidewall of the replaceable plate and are arranged in a ring array.

2. A high-efficiency anti-impact plate according to claim 1, characterized in that, The length, width, and thickness of the replaceable plate are the same as the length, width, and thickness of the mounting port.

3. A high-efficiency anti-impact plate according to claim 1, characterized in that, A backplate is fixedly installed on the rear side of the replaceable plate. The length and width of the backplate are both larger than those of the replaceable plate.

4. A high-efficiency anti-impact plate according to claim 3, characterized in that, The main anti-impact zone has threaded holes at each of the four corners, and the back plate has mounting holes at each of the four corners. The mounting holes and threaded holes are set one-to-one, and mounting bolts are installed in the mounting holes and screwed into the threaded holes.

5. A high-efficiency anti-impact plate according to claim 4, characterized in that, The pressure-reducing holes are arranged in a ring array, and the diameter of the pressure-reducing holes increases sequentially from the inside to the outside.

6. A high-efficiency anti-impact plate according to claim 5, characterized in that, The pressure relief hole is a stepped hole, with the larger diameter hole of the stepped hole located on the side away from the back plate, and the smaller diameter hole of the pressure relief hole penetrating through the back plate.

7. A high-efficiency anti-impact plate according to claim 6, characterized in that, A boss is fixedly installed at the center of the replaceable plate, and the boss is directly opposite the steam inlet of the tubular steam and water heat exchanger.

8. A high-efficiency anti-impact plate according to claim 7, characterized in that, A rib is fixed at the small diameter end of the inner cavity of the pressure reducing hole. The rib is left when the pressure reducing hole is opened, and the central axis of the rib points to the center of the boss.

9. A high-efficiency anti-impact plate according to claim 7, characterized in that, The surfaces of the impact protection plate, replaceable plate, and back plate, as well as the holes on them, are all coated with a wear-resistant coating. The coating material is WC-Co tungsten carbide, and the coating thickness is 0.25-0.35mm.

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