Corrosion-resistant and wear-resistant boiler water-cooled wall structure

Abstract

The utility model belongs to the technical field of boiler transformation, and relates to an anti-corrosion and wear-resistant boiler water-cooled wall structure which comprises a water-cooled wall pipe body, a wall-attached air nozzle unit and a hot secondary air pipe. The close-to-wall air nozzle unit comprises a plurality of close-to-wall air nozzles; on the side wall of the water-cooled wall tube body, the multiple wall-attached air nozzles are distributed in multiple layers from top to bottom, and the multiple layers are of an inverted triangle structure; an anti-corrosion and wear-resistant composite coating is sprayed on the water cooling wall pipe body in the surrounding area of the wall-attached air nozzle unit; and the hot secondary air pipe is arranged outside the water-cooled wall pipe body and is communicated with the close-to-wall air nozzle unit. According to the utility model, by designing a plurality of close-to-wall air nozzles, hot secondary air is introduced into the water-cooled wall tube body, so that the anti-wear effect of the water-cooled wall is greatly improved; and meanwhile, an anti-corrosion and wear-resistant composite coating is sprayed on the water wall pipe body around the close-to-wall air nozzle, so that the adaptability to high-sulfur coal types is improved, and the corrosion resistance is enhanced.

Description

Technical Field

[0001] The utility model belongs to the technical field of boiler transformation and relates to a corrosion-resistant and wear-resistant boiler water-cooled wall structure. Background Art

[0002] Boiler is one of the main equipments in power plant, especially direct current boiler, the main fuel of power plant boiler is coal. In the actual operation of boiler, with the changes in coal market, the intensity of economic coal blending is gradually increasing. The high sulfur coal (sulfur content is about 2.0%) entering the boiler will cause high temperature corrosion to the water-cooled wall. In addition, the economic coal with large amount of ash will cause serious thinning of the water-cooled wall in the folding angle area and the water-cooled wall elbow around the burner due to erosion and wear, with an estimated area of ​​about 80㎡. Therefore, in order to make the anti-wear performance of the water-cooled wall surface more reliable and to ensure the safe and stable operation of the boiler water-cooled wall, it is necessary to carry out corrosion-resistant and wear-resistant transformation of the water-cooled wall.

[0003] A Chinese patent document with application number CN201720713827.6 discloses an anti-wear device for boiler water-cooled wall tubes, comprising a furnace wall and a water-cooled wall tube, wherein an exhaust port is arranged at the upper part of the furnace wall, a guide protection plate is arranged around the exhaust port, the furnace wall is surrounded by a furnace, a fuel cavity is arranged at the lower part of the furnace, and an air outlet is arranged at the lower side of the fuel cavity; the water-cooled wall tubes are arranged circumferentially along the inner wall of the furnace wall, a plurality of layers of guide transverse plates are arranged along the axial direction of the water-cooled wall tubes, a plurality of rows of guide vertical plates are arranged along the axial direction of the water-cooled wall tubes, a heat-resistant plate is stamped and welded on the outer surface of the water-cooled wall tubes on the upper side of the uppermost guide transverse plates, a water-cooled wall connecting plate is arranged on the inner side surface of the furnace wall, a thermal insulation material layer is arranged on the outer side surface of the furnace wall, and a protective shell is arranged on the outer side surface of the thermal insulation material layer. The guide plate is used to guide the movement trajectory of the material particles in the furnace, change the flow direction of the internal circulating wall flow and the eddy flow direction of the material particles at the four corners of the furnace, so that the material particle flow flows to the center of the furnace to avoid collision and shearing with the water-cooled wall tubes, thereby completely curing the shear wear of the water-cooled wall by the wall flow and corner eddy flow; the guide plate can effectively destroy the eddy flow formed by the material flow at the uneven tube wall, reduce the shear collision between the material particles and the water-cooled wall, avoid the wear of the water-cooled wall tubes by solid materials, and play a role in protecting the water-cooled wall.

[0004] Although the above method sets a guide plate on the exhaust port to prevent solid materials from wearing the water-cooled wall tubes, the wear and thinning area of ​​the water-cooled walls on both sides is large and the degree of corrosion is different in different places. The anti-wear effect of setting the guide plate is still poor. In response to the situation where high-temperature corrosion of the water-cooled wall occurs, the existing method is to set a coating on the water-cooled wall. For example, referring to the patent document with application number 201911282562.9, a ceramic-metal composite material coating is set on the fire surface of the water-cooled wall. However, the temperature of the coating is high during spraying and it is easy to deform. More importantly, the existing coating has low adaptability to high-sulfur coal. When high-sulfur coal is used for a long time, the continuous high temperature in the boiler aggravates the corrosion. Utility Model Content

[0005] Aiming at the technical problems of poor anti-wear effect and aggravated corrosion in the existing water-cooled wall reconstruction, the utility model provides a boiler water-cooled wall structure.

[0006] The utility model designs a plurality of wall-attached wind nozzles on the water-cooled wall tube body, introduces hot secondary air into the wall-attached wind nozzles, greatly improving the anti-wear effect of the water-cooled wall; at the same time, an anti-corrosion and wear-resistant composite coating is sprayed on the water-cooled wall tube body around the wall-attached wind nozzles, thereby improving the adaptability to high-sulfur coal and enhancing the corrosion resistance.

[0007] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0008] A corrosion-resistant and wear-resistant boiler water-cooled wall structure, comprising a water-cooled wall tube body, a wall-attached air nozzle unit and a hot secondary air duct;

[0009] The wall-attached air nozzle unit comprises a plurality of wall-attached air nozzles; on the side wall of the water-cooled wall tube body, the plurality of wall-attached air nozzles are distributed in multiple layers from top to bottom, and the multiple layers are in an inverted triangle structure;

[0010] The water-cooled wall tubes around the wall-attached wind nozzle units are sprayed with an anti-corrosion and wear-resistant composite coating;

[0011] The hot secondary air duct is arranged outside the water-cooled wall tube body and is communicated with the wall-attached air nozzle unit.

[0012] It is further defined that the wall-attached wind nozzle is tilted downward with an inclination angle of 5° to 15°.

[0013] It is further defined that the size of the wall-mounted wind nozzle is such that the jet length is 5 m.

[0014] It is further defined that there are twelve wall-attached wind nozzles, which are distributed in four layers from top to bottom on the side wall of the water-cooled wall tube body, with four nozzles distributed in each of the upper two layers and two nozzles distributed in each of the lower two layers; the wall-attached wind nozzles of each layer are arranged side by side along the radial direction of the water-cooled wall tube body.

[0015] It is further defined that there are two wall-mounted wind nozzle units, which are arranged on opposite side walls of the water-cooled wall tube body.

[0016] It is further defined that the anti-corrosion and wear-resistant composite coating comprises an anti-wear layer and an anti-corrosion layer which are sequentially coated and connected; the anti-wear layer contacts the side wall of the water-cooled wall tube body, the thickness of the anti-corrosion layer is greater than 150μm, and the total thickness of the anti-corrosion and wear-resistant composite coating is 250μm to 300μm.

[0017] It is further defined that the anti-wear layer is an aluminum-based alloy layer, and the anti-corrosion layer is a nickel-chromium-titanium alloy layer.

[0018] It is further defined that the corrosion-resistant and wear-resistant boiler water-cooled wall structure also includes a booster fan, an air regulator and a handle damper. The handle damper is placed on the wall-attached air nozzles on the outer wall of the water-cooled wall tube body. The number of the handle dampers is the same as the number of the wall-attached air nozzles and corresponds one to one. Each handle damper is connected to the corresponding wall-attached air nozzle. The booster fan and the air regulator are both located outside the water-cooled wall tube body. The hot secondary air duct is connected to multiple handle dampers via the booster fan and the air regulator.

[0019] It is further defined that the corrosion-resistant and wear-resistant boiler water-cooled wall structure also includes an expansion joint arranged between the handle damper and the wall-attached air nozzle.

[0020] It is further defined that the corrosion-resistant and wear-resistant boiler water-cooled wall structure also includes a flue gas sampling tube arranged on the water-cooled wall tube body.

[0021] Compared with the prior art, the beneficial effects of the utility model are:

[0022] 1. The utility model designs a wall-attached wind nozzle unit in the wear area on the water-cooled wall tube body, introduces hot secondary air into the wall-attached wind nozzle, and reduces the temperature in the wear area on the water-cooled wall tube body; at the same time, an anti-corrosion and wear-resistant composite coating is sprayed around the wall-attached wind nozzle, which greatly improves the anti-wear effect, improves the adaptability to high-sulfur coal, and enhances corrosion resistance.

[0023] 2. In the utility model, on the side wall of the water-cooled wall tube body, multiple wall-attached air nozzles are distributed in multiple layers from top to bottom, and the multiple layers form an inverted triangle structure. Such a design is consistent with the high-temperature corrosion of the boiler furnace, and while ensuring the safety and stability of the boiler water-cooled wall, it can also reduce the cost of transformation.

[0024] 3. In the utility model, the anti-corrosion and wear-resistant composite coating includes an anti-wear layer and an anti-corrosion layer which are sequentially coated and connected; the anti-wear layer is an aluminum-based alloy layer, and the anti-corrosion layer is a nickel-chromium-titanium alloy layer. The anti-corrosion and wear-resistant composite coating formed in this way has a service life of more than 2 years, making the high-temperature corrosion resistance and wear resistance of the water-cooled wall surface more reliable, which can effectively solve the problems of high-temperature corrosion and wear and improve the adaptability of high-sulfur coal.

[0025] 4. In the utility model, by arranging a booster fan, an air regulator and a handle air door, not only can the hot secondary air be well introduced into the wall-attached air nozzle unit, and then introduced into the water-cooled wall tube body, the temperature of the high-temperature zone in the water-cooled wall tube body is reduced, and the severe corrosion and wear caused by high temperature is effectively prevented; at the same time, the air intake volume is adjusted by the air regulator and the handle air door, and the operation is more flexible.

[0026] 5. In the utility model, a flue gas sampling tube or a CO sensor is arranged on the water-cooled wall tube body to collect the CO content (reducing atmosphere) in the flue gas in the water-cooled wall tube body. When the CO content exceeds the standard, the air volume of the hot secondary air is increased by the air regulator and the handle damper, and the reducing atmosphere is blown out by the hot secondary air, thereby reducing wear and ensuring safe operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the overall structure diagram of the water-cooled wall tube;

[0028] Figure 2 This is a schematic diagram of the layout of the wall-mounted wind nozzle units on the front side wall;

[0029] Figure 3 It is a schematic diagram of the connection between the wall-mounted air nozzle and the hot secondary air duct;

[0030] in:

[0031] 1- water-cooled wall tube body; 101- left side wall; 102- front side wall; 2- wall-attached air nozzle unit; 201- wall-attached air nozzle; 3- booster fan; 4- air register; 5- hot secondary air duct; 6- air preheater. DETAILED DESCRIPTION

[0032] The technical solution protected by the utility model is now described in detail in conjunction with the accompanying drawings and embodiments. However, it is obvious that the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0033] The existing boiler in the power plant is a high-efficiency supercritical transformer-operated DC boiler. The boiler water-cooled wall structure is as follows: Figure 1As shown. The water-cooled wall tube body 1 is a columnar tube body structure, which is mainly composed of a left wall 101, a front side wall 102, a right wall and a rear side wall that connect the columnar tubes in sequence. On the left wall 101 and the right wall, a soot blower, a burnout air layer (upper burnout air layer and lower burnout air layer), a reducing air layer, and a burner layer (upper burner, middle burner and lower burner) are arranged from top to bottom. In actual use, due to the high temperature of the boiler, high-temperature corrosion will occur on the side wall of the water-cooled wall tube body 1, and the scouring and wear of the water-cooled wall will cause serious thinning of the tube wall; at the same time, since the sulfur content of the coal entering the furnace is about 2.0% on average, the high-temperature corrosion will be aggravated. Therefore, the utility model transforms the boiler water-cooled wall according to the actual corrosion and wear conditions.

[0034] Example 1

[0035] See also Figure 1 The present embodiment provides a corrosion-resistant and wear-resistant boiler water-cooled wall structure, including a water-cooled wall tube body 1, a wall-attached air nozzle unit 2 and a hot secondary air duct 5.

[0036] The wall-attached wind nozzle unit 2 includes a plurality of wall-attached wind nozzles 201; on the side wall of the water-cooled wall tube body 1, the plurality of wall-attached wind nozzles 201 are distributed in multiple layers from top to bottom, and an inverted triangle structure is formed between the multiple layers; an anti-corrosion and wear-resistant composite coating is sprayed on the water-cooled wall tube body 1 in the area surrounding the wall-attached wind nozzle unit 2; the hot secondary air duct 5 is placed outside the water-cooled wall tube body 1 and is connected to the wall-attached wind nozzle unit 2.

[0037] Preferably, since the boiler water-cooled wall is a columnar tube structure, there are two wall-attached wind nozzle units 2, which are arranged on opposite side walls of the water-cooled wall tube body 1, that is, the wall-attached wind nozzle units 2 are respectively arranged on the front side wall 102 and the rear side wall, and the arrangement method and arrangement position are the same.

[0038] The following description will be made by taking the arrangement of the wall-attached air nozzle unit 2 on the front side wall 102 as an example.

[0039] The thickness of the four side walls of the water-cooled wall tube body 1 was measured during operation. The measuring point was based on the equipment layer arranged on the left wall. The upper and lower layers were separated by 1.5m, and the left and right intervals were 1m. The measuring starting point was 2m away from the front side wall and the rear side wall. Two sets of values ​​were measured at each location. Statistics show that the wall thickness in the area below the upper burnout air layer and above the middle burner is relatively thin, indicating that the corrosion in this area is serious and recorded as a high-temperature corrosion area, and the thickness is in an inverted triangle shape from top to bottom.

[0040] According to the range and degree of high-temperature corrosion zone determined by the water-cooled walls on both sides of the power plant, the wall-attached wind nozzle unit 2 includes a total of twelve wall-attached wind nozzles 201. The twelve wall-attached wind nozzles 201 are distributed in multiple layers from top to bottom, and the multiple layers form an inverted triangle structure, which is in line with the changing trend of decreasing wall thickness in the high-temperature corrosion zone.

[0041] See also Figure 2 Specifically, according to the size of the front side wall 102, the twelve wall-mounted wind nozzles 201 are divided into four layers, the top two layers, each with four, and the bottom two layers, each with two. This design makes the coverage area larger and the effect better.

[0042] Preferably, when the width of the front side wall 102 is 15.46m, from the top to the bottom, the first and second layers, the wall-attached wind nozzles of the two layers are designed in two rows and four columns, and among the four wall-attached wind nozzles in each layer, the horizontal spacing between the center points of two adjacent wall-attached wind nozzles is 2.74m, and the height distance between the two layers of wall-attached wind nozzles is 4.14m; from the top to the bottom, the third and fourth layers, the wall-attached wind nozzles of the two layers are designed in two rows and two columns, and the two wall-attached wind nozzles 201 in each layer, the horizontal spacing between the center points of the two wall-attached wind nozzles is 1.37m, and the height distance between the two layers of wall-attached wind nozzles is 4.58m; the height distance between the second layer of wall-attached wind nozzles and the third layer of wall-attached wind nozzles is 4.90m.

[0043] In this embodiment, the hot secondary air duct 5 is placed outside the water-cooled wall tube body 1 and is connected to the wall-attached air nozzle unit 2. Specifically, the hot secondary air duct 5 is connected to the corresponding 12 wall-attached air nozzles through 12 branch pipes, and the hot secondary air is sent into the water-cooled wall tube body 1 through the wall-attached air nozzle 201 through the hot secondary air duct 5, so as to reduce the temperature in the boiler water-cooled wall, so as to achieve a good effect of controlling the high-temperature corrosion of the side wall, thereby avoiding the aggravation of corrosion damage in a high-temperature environment. In this embodiment, the secondary air pressure is low, and the secondary air is pressurized by the booster fan 3 and then sprayed into the water-cooled wall tube body 1, so that the gas pressure entering the water-cooled wall tube body 1 is easier to control.

[0044] In this embodiment, an anti-corrosion and wear-resistant composite coating is sprayed on the water-cooled wall tube body 1 in the area surrounding the wall-attached wind nozzle unit 2; the anti-corrosion and wear-resistant composite coating improves the wall's resistance to high-temperature corrosion and wear, slows down the rate of corrosion and wear, and extends the service life of the water-cooled wall tube body 1.

[0045] Preferably, an anti-corrosion and wear-resistant composite coating is sprayed on the inner wall and the outer wall of the water-cooled wall tube body 1 respectively to enhance the anti-corrosion and wear-resistant performance.

[0046] Example 2

[0047] In this embodiment, based on the embodiment 1, the wall-mounted wind nozzle 201 is installed at an inclined angle to increase the spray length, and the spray length is guaranteed to be 5m during operation.

[0048] Preferably, the wall-attached wind nozzle 201 adopts a direct-current wind structure to draw hot secondary air from the hot secondary air duct 5 into the water-cooled wall tube body 1, and the wall-attached wind nozzle 201 can manually adjust the size of the hot secondary air.

[0049] During implementation, the wall-attached air nozzles 201 are tilted downward, starting from the outer wall of the water-cooled wall tube body 1 and tilted downward at an angle of 5° to 15°. Preferably, the upper and middle layers tilt downward at 15°, and the lower layers tilt downward at 5°.

[0050] Preferably, the wall-attached air nozzle 201 is a circular nozzle with a nozzle diameter of Φ340 mm; and two long strip nozzles are respectively connected to the nozzle, and the size of the long strip nozzle is 98 mm (width) × 820 mm (length), and the two long strip nozzles are arranged on both sides of the side wall of the water-cooled wall tube body 1. In practice, the wind rate of the wall-attached air in the water-cooled wall tube body 1 is controlled not to exceed 3% of the total secondary air volume.

[0051] Example 3

[0052] See also Figure 3 The corrosion-resistant and wear-resistant boiler water-cooled wall structure provided in this embodiment also includes a booster fan 3, an air regulator 4 and a handle damper. The handle damper is placed on the outer wall of the water-cooled wall tube body 1 and is located near the wall-attached air nozzle 201. The number of the handle dampers is the same as the number of the wall-attached air nozzles 201 and corresponds one to one. Each handle damper is connected to the corresponding wall-attached air nozzle 201. The booster fan 3 and the air regulator 4 are both located outside the water-cooled wall tube body 1. The hot secondary air duct 5 is connected to multiple handle dampers through the booster fan 3 and the air regulator 4.

[0053] In this embodiment, the hot secondary air duct 5 is also connected to the air preheater 6. Its purpose is to introduce the hot secondary air generated by the air preheater 6 into the water-cooled wall tube body 1 through the hot secondary air duct 5 and the wall-attached air nozzle 201. This can not only improve the high-temperature corrosion resistance of the water-cooled wall tube body 1, but also realize the secondary reuse of the hot air, which is energy-saving and environmentally friendly.

[0054] Preferably, a booster fan 3 is correspondingly arranged outside the front side wall and the rear side wall, and the two booster fans 3 respectively increase the pressure head of the corresponding front side wall wall-attached wind nozzle and the pressure head of the rear side wall wall-attached wind nozzle; the booster fan 3 is variable frequency controllable to meet the air volume boosting demand of the hot secondary air.

[0055] In this embodiment, the corrosion-resistant and wear-resistant boiler water-cooled wall structure also includes an expansion joint arranged between the handle damper and the wall-mounted wind nozzle 201. The expansion joint can effectively absorb the axial deformation caused by high and low temperature changes and protect the safety of the connecting pipeline.

[0056] In this embodiment, the corrosion-resistant and wear-resistant boiler water-cooled wall structure further includes a flue gas sampling tube arranged on the water-cooled wall tube body 1; the reducing atmosphere in the water-cooled wall tube body 1 is measured by flue gas sampling, so as to find a way to reduce high-temperature corrosion according to the content of the reducing atmosphere. This is because the higher the content of the reducing atmosphere, the faster the corrosion and wear rate will be.

[0057] Preferably, the reducing atmosphere is CO, so the flue gas in the water-cooled wall tube body 1 is collected through the flue gas sampling tube, and the CO concentration in the flue gas is detected. When the CO concentration exceeds the limit, the air volume of the hot secondary air is increased through the air regulator 4. A large amount of hot secondary air can quickly bring the reducing atmosphere out of the water-cooled wall tube body 1, reduce the corrosion rate, and avoid the danger caused by the high CO concentration. During implementation, the limit of CO concentration is 100μL / L.

[0058] In this embodiment, another implementation method of CO concentration detection is to set a CO sensor on the water-cooled wall tube body 1 to monitor the CO concentration in the flue gas in real time, and adjust the air volume of the hot secondary air according to the monitored CO concentration.

[0059] Example 4

[0060] Based on Example 1, in this embodiment, the anti-corrosion and wear-resistant composite coating includes an anti-wear layer and an anti-corrosion layer which are sequentially coated and connected; the anti-wear layer is in contact with the side wall of the water-cooled wall tube body 1, the thickness of the anti-corrosion layer is greater than 150μm, and the total thickness of the anti-corrosion and wear-resistant composite coating is 250μm to 300μm.

[0061] Preferably, the anti-wear layer is an aluminum-based alloy layer, and the anti-corrosion layer is a nickel-chromium-titanium alloy layer, in which nickel (Ni) ≥ 55%, chromium (Cr) ≥ 42%, and the rest is titanium (Ti).

[0062] Preferably, the aluminum-based alloy layer is formed of LZ-5 aluminum-based alloy (bottom wire), and the nickel-chromium-titanium alloy layer is formed of 45CT nickel-chromium-titanium alloy wire (surface wire). During implementation, cold spraying is performed with a supersonic arc gun, and the total coating thickness is controlled at 250μm to 300μm.

[0063] Preferably, 45CT is imported 72TSW, which is a pre-alloyed material. It is mainly applied with METALSPRAY EXCALIBUR2000 supersonic arc spraying system. It is a high-performance anti-corrosion coating specially used for sulfur corrosion and oxidation corrosion protection in high-temperature environment of power plant boilers. The main component of 45CT (72TSW) is nickel-chromium alloy. The metallographic design can meet the chemical corrosion resistance of boilers in high temperature and sulfurized environment; and 45CT (72TSW) is a non-consumable coating, and the average loss of the coating is less than 0.0005 inches (13μm) per year, that is, 0.013mm. Compared with carbon steel, its sulfur corrosion resistance is more than 60 times higher, which can not only block corrosion, but also prevent the thinning of boiler water-cooled wall tubes. The Ni and Cr metals contained in 45CT (72TSW) are highly evenly distributed in the alloy, thus ensuring that the coating has excellent protective performance. See Table 1 for the coating performance of 45CT (72TSW).

[0064] Table 1 Performance index of 45CT coating

[0065] project index Porosity ＜0.5％ Bonding strength ≥50Mpa Coating hardness ≥67HRC Oxide layer of coating ≤0.5％ Thermal shock resistance of coating More than 50 times High temperature oxidation resistance of coating <![CDATA[6.3mg / cm 2 (750℃ oxidation for 250h)]]> Coating heat resistance ≥1480℃ Substrate temperature ≤120℃ Sealing cover High temperature resistant, corrosion resistant and anti-coking nano ceramic coating

[0066] From the above, it can be seen that the coating alloy containing more than 40% Cr forms stable chromium oxide during the spraying process, which can hinder the formation of unstable iron oxide, nickel oxide, iron sulfide, and nickel sulfide in the coating. Since the chromium content is more than 40%, the chromium oxide has a very dense lattice structure, which is tighter than the corrosive element sulfur particles. This tight structure acts as a barrier to limit the penetration of sulfur through the coating.

[0067] The Ni contained in 45CT (72TSW) enhances the mechanical properties of the coating. Ni has the characteristic of super adhesion, which makes the coating adhere to the substrate very firmly. Ni is also ductile, which makes the coating have almost the same thermal expansion coefficient as the carbon steel water pipe substrate. Therefore, it can resist the periodic stress of the boiler, effectively prevent the occurrence of mechanical peeling of the coating, and enhance the corrosion resistance of the anti-corrosion spray layer.

[0068] 45CT (72TSW) also contains Ti, which can further enhance the adhesion strength of the anti-corrosion spray layer. During the atomization process, the reaction between titanium and oxygen is conducive to the formation of chromium oxide, so that the temperature of the particle reaches the highest, thereby improving the spraying efficiency.

[0069] In this embodiment, before cold spraying with a supersonic arc gun, brown corundum is used for sandblasting to remove rust and roughen the surface of the pipeline to a roughness of Rz80-120 μm as specified in GB11373 "General Rules for Pretreatment of Thermal Sprayed Metal Surfaces". The sandblasting parameters are: compressed air of not less than 0.6Mpa, which must be dried before exhausting; sand material: 14#-20# brown corundum.

[0070] The process requirements for spraying are as follows: (1) The spray coating should be completed within 4 hours after sandblasting; (2) The base layer (aluminum-based alloy layer) should be sprayed with a supersonic arc gun, regardless of thickness, covering the entire treated surface, and the roughness after priming should be greater than Ra10μm; (3) After priming, an anti-corrosion layer should be arc sprayed with a thickness greater than 150μm.

[0071] In this embodiment, the total coating thickness of the anti-corrosion spray layer is 250 μm to 300 μm. The coating is resistant to high temperature, wear and corrosion, has a melting point greater than 1700°C, can work for a long time in an environment of 1400°C, has a linear expansion coefficient similar to that of 15CrMo boiler pipes, has high hardness, wear resistance equivalent to more than 18 times that of 15CrMo, and has high temperature oxidation resistance. During spraying, the substrate temperature is controlled to be ≤120°C, and the substrate does not deform. After spraying, check that there are no obvious pores, peeling, cracking, etc. on the surface of the spray layer.

[0072] In this embodiment, spraying the anti-corrosion spray layer on the water-cooled wall in the high-temperature corrosion area can effectively solve the problems of high-temperature corrosion and wear, and improve the adaptability of the coating to high-sulfur coal. Even if 2.0% high-sulfur coal is burned, the high-temperature corrosion resistance of the water-cooled wall surface in the high-temperature corrosion area is more reliable, the life of the anti-corrosion spray layer reaches more than 2 years, and the anti-wear service life of the water-cooled wall tube body 1 reaches more than 6 years.

[0073] In addition, in the utility model, the anti-corrosion spray layer can also be sprayed on the corresponding soot blower area on the water-cooled wall tube body 1, the water-cooled wall bend area near the burner around the burner, and the flame folding angle area. During spraying, the surface of the wall of the water-cooled wall tube body 1 is clad with a wear-resistant nickel-chromium alloy, and the thickness of the cladding layer is 0.6mm to 0.8mm. The surface is smooth and not prone to coking, so that the shear strength of the anti-corrosion spray layer and the water-cooled wall tube body 1 substrate is greater than 400MPa, and the thermal conductivity is twice that of the boiler tube parent material, which does not affect the heat exchange performance of the water-cooled wall tube body 1.

[0074] To sum up, in this embodiment, the water-cooled wall tube body 1 is modified by the wall-attached wind nozzle unit and the anti-corrosion spray layer, which can greatly improve the adaptability of the boiler to burning economical coal, reduce coal burning costs, extend the service life of the water-cooled wall, and effectively avoid the problem of water-cooled wall tube burst caused by high-temperature corrosion and excessive wear, thereby ensuring the safe and stable operation of the unit.

[0075] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the utility model in detail. It should be understood that the above description is only the specific implementation method of the utility model and is not used to limit the protection scope of the utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the utility model should be included in the protection scope of the utility model.

Claims

1. A corrosion-resistant and wear-resistant boiler water-cooled wall structure, characterized in that: It comprises a water-cooled wall tube body (1), a wall-attached air nozzle unit (2) and a hot secondary air duct (5); The wall-attached air nozzle unit (2) comprises a plurality of wall-attached air nozzles (201); on the side wall of the water-cooled wall tube body (1), the plurality of wall-attached air nozzles (201) are distributed in multiple layers from top to bottom, and the multiple layers form an inverted triangle structure; The water-cooled wall tube body (1) around the wall-attached air nozzle unit (2) is sprayed with an anti-corrosion and wear-resistant composite coating; The hot secondary air duct (5) is placed outside the water-cooled wall tube body (1) and is connected to the wall-attached air nozzle unit (2).

2. The corrosion-resistant and wear-resistant boiler water-cooled wall structure according to claim 1 is characterized in that: The wall-attached air nozzle (201) is inclined downward, with an inclination angle of 5° to 15°.

3. The corrosion-resistant and wear-resistant boiler water-cooled wall structure according to claim 2 is characterized in that: The jet length of the wall-attached wind nozzle (201) is 5 m.

4. The corrosion-resistant and wear-resistant boiler water-cooled wall structure according to claim 1 is characterized in that: There are twelve wall-attached wind nozzles (201) distributed in four layers from top to bottom on the side wall of the water-cooled wall tube body (1), with four nozzles distributed in each of the upper two layers and two nozzles distributed in each of the lower two layers. The wall-attached wind nozzles (201) in each layer are arranged side by side along the radial direction of the water-cooled wall tube body (1).

5. The corrosion-resistant and wear-resistant boiler water-cooled wall structure according to claim 1 is characterized in that: There are two wall-attached air nozzle units (2), which are arranged on opposite side walls of the water-cooled wall tube body (1).

6. The corrosion-resistant and wear-resistant boiler water-cooled wall structure according to claim 1 is characterized in that: The anti-corrosion and wear-resistant composite coating comprises an anti-wear layer and an anti-corrosion layer which are sequentially coated and connected; the anti-wear layer contacts the side wall of the water-cooled wall tube body (1), the thickness of the anti-corrosion layer is greater than 150 μm, and the total thickness of the anti-corrosion and wear-resistant composite coating is 250 μm to 300 μm.

7. The corrosion-resistant and wear-resistant boiler water-cooled wall structure according to claim 6 is characterized in that: The anti-wear layer is an aluminum-based alloy layer, and the anti-corrosion layer is a nickel-chromium-titanium alloy layer.

8. The corrosion-resistant and wear-resistant boiler water-cooled wall structure according to claim 1 is characterized in that: The corrosion-resistant and wear-resistant boiler water-cooled wall structure also includes a booster fan (3), an air regulator (4) and a handle air door. The handle air door is placed on the wall-attached air nozzle (201) on the outer wall of the water-cooled wall tube body (1). The number of the handle air doors is the same as the number of the wall-attached air nozzles (201) and corresponds one to one. Each handle air door is connected to the corresponding wall-attached air nozzle (201). The booster fan (3) and the air regulator (4) are both located outside the water-cooled wall tube body (1). The hot secondary air duct (5) is connected to a plurality of handle air doors respectively via the booster fan (3) and the air regulator (4).

9. The corrosion-resistant and wear-resistant boiler water-cooled wall structure according to claim 1, characterized in that: The corrosion-resistant and wear-resistant boiler water-cooled wall structure also includes an expansion joint arranged between the handle damper and the wall-attached air nozzle (201).

10. The corrosion-resistant and wear-resistant boiler water-cooled wall structure according to any one of claims 1 to 8, characterized in that: The corrosion-resistant and wear-resistant boiler water-cooled wall structure also includes a flue gas sampling tube arranged on the water-cooled wall tube body (1).

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