Water-cooled wall pipeline coated with high-heat-transfer wear-resistant coating and preparation method of water-cooled wall pipeline

Abstract

The invention discloses a water-cooled wall pipeline coated with a high-heat-transfer wear-resistant coating and a preparation method of the water-cooled wall pipeline, and relates to the technical field of heat and mass transfer, the water-cooled wall pipeline comprises a main pipeline and a plurality of mixing elements; each mixing element is fixed on the inner wall surface of the main pipeline; the inner wall surface and the outer wall surface of the main pipeline and the surfaces of the mixing elements are coated with high-heat-transfer wear-resistant coatings; the high-heat-transfer wear-resistant coating comprises a first coating and a second coating which are sequentially arranged from inside to outside. The invention has the advantages of effectively improving the heat transfer efficiency, enhancing the wear resistance and reducing the thermal deviation, thereby prolonging the service life and improving the safety and stability of a boiler system.

Description

Technical Field

[0001] This invention relates to the field of heat and mass transfer technology, specifically to a water-cooled wall pipe coated with a high heat transfer and wear-resistant coating and its preparation method. Background Technology

[0002] As a core heat exchange component of a boiler system, the water-cooled wall plays a crucial role in absorbing high-temperature radiant heat from the furnace, protecting the furnace wall structure, and generating steam. In actual operation, the water-cooled wall is subjected to extreme combined conditions of high temperature, high pressure, corrosive media, and the erosion of solid particles. Its inner wall surface is frequently subjected to oxygen corrosion and flow-accelerated corrosion, leading to localized thinning and even perforation of the tube wall. Simultaneously, the continuous impact of fly ash particles causes mechanical wear, further weakening the pipe structure. More significantly, the uneven distribution of heat load within the furnace interacts with fluid dynamics, resulting in a significantly uneven flow of the working fluid within the tubes, creating a thermal deviation. This thermal deviation causes excessive differences in heat absorption between different tube sections, leading to abnormally high temperatures in localized areas and easily inducing overheating and tube rupture accidents.

[0003] Existing water-cooled wall structures generally lack effective fluid mixing mechanisms, failing to homogenize the temperature and state of the fluid inside the pipes, thus exacerbating thermal stress concentration and material fatigue. Furthermore, traditional protective coatings often struggle to balance high heat transfer performance and wear resistance under high temperature and pressure environments, leading to coating peeling and failure, resulting in decreased pipe thermal efficiency and shortened maintenance cycles. These problems collectively restrict the safe and stable operation of boiler systems and their energy utilization efficiency.

[0004] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0005] In view of this, the present invention provides a water-cooled wall pipe coated with a high heat transfer and wear-resistant coating and its preparation method, which has the advantages of effectively improving heat transfer efficiency, enhancing wear resistance, reducing thermal deviation, thereby extending service life and improving the safety and stability of boiler system.

[0006] In a first aspect, the present invention provides a water-cooled wall pipe coated with a high heat transfer and wear-resistant coating, comprising: a main pipe and a plurality of mixing elements; Each of the mixing elements is fixed to the inner wall of the main pipe; the inner and outer walls of the main pipe and the surface of the mixing elements are coated with a high heat transfer and wear-resistant coating; the high heat transfer and wear-resistant coating includes a first coating and a second coating arranged sequentially from the inside to the outside.

[0007] In one optional embodiment, the first coating is composed of bisphenol A diglycidyl ether, neopentyl glycol diglycidyl ether, polyetheramine, curing agent, nano ZrO2, graphene, polyvinyl alcohol, and ethyl acetate.

[0008] In one optional embodiment, the second coating is composed of nano-ZrO2, TiO2, cyclomethylsiloxane, 1H,1H,2H,2H It consists of perfluorodecyltriethoxysilane, curing agent, ethyl acetate, multi-walled carbon nanotubes, a mixture of concentrated sulfuric acid and concentrated nitric acid, and deionized water.

[0009] In one optional embodiment, each of the hybrid elements includes two cross-connected straight plate segments; each straight plate segment is leaf-shaped and has a circular hole; the opening angle between the two straight plate segments is any one of 30°, 45°, 60°, 75° and 90°.

[0010] In one optional embodiment, the number of mixing elements is 6, which are spaced apart along the axial direction of the main pipe and are centrally symmetrically distributed about the central axis of the main pipe; adjacent mixing elements are rotated out of each other, with an out-of-place angle of any one of 30°, 45°, 60° and 90°.

[0011] In one alternative implementation, the ratio of the length to the diameter of the main pipe is 31:2.

[0012] In one optional embodiment, the length:width:height ratio of the two straight sections in the hybrid element is 40:10:1.

[0013] In one alternative embodiment, the length ratio of the mixing section with mixing elements to the non-mixing section without mixing elements on the main pipeline is 21:10.

[0014] Secondly, the present invention also provides a method for preparing a water-cooled wall pipe coated with a high heat transfer and wear-resistant coating, comprising the following steps: S1. Print the hybrid component using 3D printing technology. Place the main pipe and the hybrid component into the cleaning agent and heat it to 60°C for 30 minutes. After soaking, rinse with clean water until there is no obvious cleaning agent residue. Then air dry and then dry. S2. At room temperature, 1.7g of bisphenol A diglycidyl ether was preheated for 30 minutes, and then 1.08g of neopentyl glycol diglycidyl ether, 2g of polyetheramine T-403, 0.5g of curing agent and 2mL of ethyl acetate were added and magnetically stirred for 30 minutes until the mixture was homogeneous. Then, 0.06g of nano ZrO2, 2mL of ethyl acetate and 0.8g of polyvinyl alcohol were added to the resulting mixture and magnetically stirred to obtain the base coating. S3. The obtained base coating is mixed with 0.79 g of graphene under mechanical mixing at 100 r / min for 30 minutes; then, 0.05 g of curing agent is added to the mixture and stirred at 300 r / min for 1 minute; then, the first coating is obtained. S4. Mix 1g TiO2 and 1g nano ZrO2, then add to 20mL ethyl acetate and sonicate for 30min. After mixing, add 0.5g cyclomethylsiloxane and stir magnetically for 30min. Then add 0.1g cyclomethylsiloxane, 0.01g curing agent, and 0.1g 1H,1H,2H,2H. Perfluorodecyltriethoxysilane was magnetically stirred for 60 min to obtain component A. S5. Add 20g of multi-walled carbon nanotubes to a mixture of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1 and mix well. Heat and stir at a constant temperature of 60℃ for 2 hours to acidify. Cool to room temperature, dilute with distilled water and filter. Wash the acidified multi-walled carbon nanotubes with water and vacuum filter until the filtrate is neutral to obtain component B. S6. Mix 100mL of deionized water, component B, and 0.5g of cyclomethylsiloxane, then heat in a constant temperature water bath and stir for 5min. Ultrasonically disperse for 30min, then add to component A and continue ultrasonic dispersion for 30min to obtain the second coating. S7. Spraying the inner wall of the main pipeline and the surface of the mixing element: After spraying the first coating on the inner wall of the main pipeline and the surface of the mixing element with an airless spraying device, cure at 70°C for 4 hours, and then spray the second coating and cure at 70°C for 4 hours. S8. After applying the first coating to the outer wall of the main pipeline using an airless spraying device, cure it at 70°C for 4 hours. After applying the second coating, cure it at 70°C for 4 hours. S9. Connect the main pipeline to the mixing element using sealing technology, and check the airtightness and watertightness.

[0015] The present invention has the following beneficial effects: 1. The application of high heat transfer and wear-resistant coatings can improve the corrosion resistance and wear resistance of water-cooled wall pipes during operation. Multi-wall carbon nanotubes can further optimize the configuration process of high heat transfer and anti-corrosion coatings, while bringing better heat transfer performance to the high heat transfer and anti-corrosion coatings. 2. After coating with a high heat transfer and wear-resistant coating, a superhydrophobic surface is formed, which has the function of inhibiting scale formation in water-cooled wall pipes and has a good self-cleaning function. Its wear resistance enables it to work normally in high temperature and high pressure media for a long time. At the same time, the first coating is a memory coating with self-recovery, which can improve the service life.

[0016] 3. Graphene has a two-dimensional carbon layer structure with interactions and van der Waals forces between different layers. Heat can be transferred through the crystalline cubic structure and layered structure, enhancing the overall thermal conductivity. Simultaneously, the carbon atom layers of graphene can slide against each other. When graphene particles within the coating enter the interface due to wear, they act as a lubricant, reducing wear and friction.

[0017] 4. Using an airless nozzle device to spray the coating on the surface of the water-cooled wall pipes ensures the uniformity of the high heat transfer and wear-resistant coating on the inner and outer walls of the water-cooled wall pipes and the surface of the mixing elements, preventing the accumulation of the high heat transfer and wear-resistant coating or the formation of material shortages, which would affect the thermal efficiency of the water-cooled wall.

[0018] 5. Unlike existing spiral water-cooled wall pipes, the water-cooled wall pipes of this invention have several mixing elements arranged in a cross pattern inside, which can better mix the fluid inside the pipe, making the fluid homogeneous, and the temperature and state more uniform. This prevents differences in heat absorption in different parts of the water-cooled wall, which can lead to thermal deviation and cause the water-cooled wall to burst. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a water-cooled wall pipe coated with a high heat transfer and wear-resistant coating according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the hybrid element in an embodiment of the present invention; Figure 3 This is a two-dimensional streamline distribution diagram of the fluid in the main pipeline at different axial sections according to an embodiment of the present invention; Figure 4 The diagram shows the overall three-dimensional spiral streamline diagram, fluid particle flow trajectory diagram, and velocity distribution diagram at different axial sections of the fluid in the main pipeline according to an embodiment of the present invention.

[0021] Figure label: 1. Main pipe; 2. Mixing element; 21. Straight plate section. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Traditional water-cooled wall pipes are susceptible to material degradation and failure (pipe bursts, leaks) when operating under extreme conditions over long periods. Furthermore, uneven furnace environments can lead to localized overheating and other malfunctions, resulting in high maintenance costs. In addition, differences in heat absorption across different parts of the water-cooled wall can cause thermal deviations, affecting its service life and economic efficiency.

[0024] In this regard, such as Figure 1 As shown, this application provides a water-cooled wall pipe coated with a high heat transfer and wear-resistant coating. The pipe includes a main pipe 1 and a plurality of mixing elements 2. Each mixing element 2 is fixed to the inner wall surface of the main pipe 1. The inner and outer walls of the main pipe 1 and the surface of the mixing elements 2 are coated with a high heat transfer and wear-resistant coating. The high heat transfer and wear-resistant coating includes a first coating and a second coating disposed sequentially from the inside to the outside.

[0025] The main pipe 1 typically refers to the main body of the water-cooled wall pipe, used to carry the flow of the fluid medium and serving as the primary interface for heat exchange. The material of the main pipe 1 is usually a high-temperature and pressure-resistant metal alloy to withstand the extreme working environment inside the boiler. The mixing element 2 is a structure installed inside the main pipe 1, designed to promote thorough mixing of the fluid within the pipe by agitating the fluid flow, thereby achieving homogenization of fluid temperature and composition. The geometry and arrangement of the mixing element 2 can be designed according to specific fluid characteristics and mixing requirements. The high heat transfer and wear-resistant coating is a composite material layer applied to the surfaces of the main pipe 1 and the mixing element 2. Its main function is to improve the heat transfer efficiency of the pipe surface while enhancing its resistance to corrosion and wear, thus extending the service life of the pipe. The first coating is the layer closest to the substrate (i.e., the surface of the main pipe 1 or the mixing element 2) in the high heat transfer and wear-resistant coating, usually serving as a primer, providing good adhesion, basic corrosion resistance, and wear resistance. The second coating is a layer located outside the first coating in a high heat transfer and wear-resistant coating. It is usually used as a topcoat and provides better heat transfer, wear resistance, corrosion resistance and other special functions, such as superhydrophobicity or self-cleaning ability.

[0026] In one alternative embodiment, the mixing element 2 can be fixed to the inner wall of the main pipe 1 using various technical means. For example, it can be achieved through welding, riveting, bolting, or bonding. Specifically, the edge of the mixing element 2 can be firmly connected to the inner wall of the main pipe 1 by spot welding, or it can be fixed by mechanical clips. During the fixing process, it should be ensured that the mixing element 2 remains stable under fluid impact and thermal stress to avoid detachment or displacement.

[0027] In summary, the water-cooled wall pipe proposed in this embodiment effectively promotes uniform mixing of the fluid inside the pipe by setting a mixing element 2 inside the main pipe 1 and coating the inner and outer walls of the main pipe 1 and the surface of the mixing element 2 with a high heat transfer and wear-resistant coating, significantly reducing thermal deviation and the risk of local overheating. At the same time, this coating significantly improves the corrosion resistance and wear resistance of the pipe, thereby extending the service life of the water-cooled wall and reducing maintenance costs caused by material deterioration and failure.

[0028] This application further proposes that the first coating of the aforementioned water-cooled wall pipe is composed of bisphenol A diglycidyl ether, neopentyl glycol diglycidyl ether, polyetheramine, curing agent, nano ZrO2, graphene, polyvinyl alcohol, and ethyl acetate.

[0029] Specifically, bisphenol A diglycidyl ether, as the main component of the epoxy resin matrix, provides the first coating with excellent mechanical strength, good adhesion to the inner walls of the main pipe 1 and the mixing element 2, and outstanding chemical corrosion resistance. Neopentyl glycol diglycidyl ether, as an active diluent, effectively reduces the viscosity of the epoxy resin system, improves the coating's flowability and workability, and also helps improve the coating's toughness and flexibility, making it more adaptable to possible deformations during pipeline operation. Polyetheramine, as a curing agent, reacts with epoxy groups to form a dense cross-linked structure, giving the coating good flexibility, impact resistance, and water resistance, ensuring the coating's stability under complex working conditions. The curing agent further promotes the rapid cross-linking reaction of the epoxy resin system, ensuring that the coating can quickly cure under specific conditions and form a stable three-dimensional network structure. Nano-ZrO2, as a type of nano-ceramic particle, is uniformly dispersed in the coating, significantly improving the coating's hardness, wear resistance, and corrosion resistance, while also helping to improve the coating's thermal conductivity, enabling it to efficiently transfer heat while withstanding wear. Graphene, due to its extremely high thermal conductivity and excellent mechanical strength, has been introduced to significantly improve the overall thermal conductivity and wear resistance of coatings, as well as enhance their toughness, effectively resisting particle erosion and thermal stress. Polyvinyl alcohol, as a water-soluble polymer, can be used as a dispersant, film-forming agent, or thickener to improve the stability and application performance of the coating system, and may also improve the adhesion between the coating and the substrate to some extent. Ethyl acetate, as an organic solvent, is used to dissolve and disperse various components in the coating, adjust the viscosity of the coating system to facilitate uniform application by spraying or other methods, and promote leveling of the coating before curing.

[0030] This application further proposes that the aforementioned second coating is composed of nano-ZrO2, TiO2, cyclomethylsiloxane, 1H,1H,2H,2H It consists of perfluorodecyltriethoxysilane, curing agent, ethyl acetate, multi-walled carbon nanotubes, a mixture of concentrated sulfuric acid and concentrated nitric acid, and deionized water.

[0031] Among them, nano-ZrO2, as a high-performance ceramic material, possesses excellent hardness, toughness, wear resistance, and corrosion resistance. Its nanoscale size allows it to form a dense structure in coatings, effectively improving the mechanical strength and erosion resistance of the coating. As a reinforcing phase dispersed in the polymer matrix, it hinders crack propagation, thus significantly improving the wear resistance of the coating. TiO2 is a widely used inorganic material with good chemical stability and corrosion resistance. In coatings, TiO2 can act as a filler, improving the hardness and wear resistance of the coating, while also improving its adhesion and uniformity. Cyclomethylsiloxanes are a class of organosilicon compounds with excellent high-temperature resistance, weather resistance, hydrophobicity, and low surface energy properties. In coatings, it is often used as a film-forming substance or modifier, capable of forming a dense and flexible coating, improving its heat resistance and corrosion resistance. 1H,1H,2H,2H Perfluorodecyltriethoxysilane is a fluorosilane coupling agent with extremely strong hydrophobic and oleophobic properties and low surface energy. In coatings, it can significantly reduce the surface energy of the coating, giving it excellent antifouling, easy-to-clean, and anti-adhesion properties. Through chemical bonding with the substrate or other components in the coating, it can also improve the adhesion between the coating and the substrate and enhance the coating's corrosion resistance. The curing agent is an indispensable component in the coating system, used to initiate or accelerate the cross-linking reaction of the coating resin, transforming it from a liquid or plastic state to a solid state, forming a coating film with specific physicochemical properties. The type and amount of curing agent directly affect the final properties of the coating, such as curing speed, hardness, toughness, and chemical resistance. Ethyl acetate is a commonly used organic solvent with good solubility and a moderate evaporation rate. In the coating preparation process, it is mainly used as a diluent to adjust the viscosity of the coating, making it easy to spray or coat, and ensuring uniform dispersion of the coating components. Multi-walled carbon nanotubes are nanomaterials with unique structures and excellent properties, exhibiting extremely high strength, modulus, thermal conductivity, and electrical conductivity. In coatings, multi-walled carbon nanotubes (MWCNTs) can serve as reinforcing materials, significantly improving the coating's mechanical strength, toughness, and wear resistance. Their high aspect ratio allows them to form a network structure within the coating, effectively dispersing stress and inhibiting crack propagation. A mixture of concentrated sulfuric acid and concentrated nitric acid is commonly used for acidification of MCCNTs. The purpose of acidification is to introduce oxygen-containing functional groups onto the surface of the carbon nanotubes, thereby improving their dispersibility in solvents and enhancing their interfacial bonding with the polymer matrix, allowing them to be better dispersed in the coating system and exert their reinforcing effect. Deionized water is specially treated water to remove most ionic impurities. In coating preparation, deionized water is commonly used as a solvent or dispersion medium, especially in steps involving aqueous systems or requiring high-purity solvents, such as in the cleaning process after acidification of MCCNTs, to thoroughly remove residual acid and ensure the purity of the material.

[0032] like Figure 1-2As shown, this application further proposes that each of the hybrid elements 2 includes two cross-connected straight plate segments 21; each straight plate segment is leaf-shaped and has a circular hole; the opening angle between the two straight plate segments is any one of 30°, 45°, 60°, 75° and 90°.

[0033] Specifically, each mixing element 2 comprises two cross-connected straight plate segments 21. This structural design enables the mixing element 2 to effectively split and re-merge the fluid, thereby generating radial mixing and axial vortices within the pipe. The cross-connected straight plate segments 21 force the fluid to change direction through their geometry, breaking the laminar boundary layer and promoting uniform fluid distribution across the entire cross-section. The straight plate segments 21 can be integrally formed using 3D printing technology, ensuring their structural strength and reliable fixation to the inner wall of the main pipe 1. Each straight plate segment is blade-shaped. The blade design is a streamlined structure that reduces fluid resistance and pressure drop, while generating favorable vortices as the fluid flows around the blade surface, further enhancing the mixing effect. Compared to simple flat or rectangular structures, the blade-shaped straight plate segments 21 guide the fluid more smoothly, avoiding excessive shear stress and thus reducing potential wear on the coating. The blade shape can be achieved through precise mold forming or CNC machining.

[0034] Furthermore, circular holes are formed on the blade-shaped straight plate section 21 to further optimize fluid mixing and heat transfer performance. These holes allow some fluid to pass directly through the straight plate section 21, forming a local jet that interacts with the fluid bypassing the straight plate section 21, generating a more complex turbulent structure and thus improving mixing efficiency. Simultaneously, the presence of the circular holes increases the contact area between the fluid and the surface coating of the mixing element 2, contributing to improved overall heat transfer. In addition, the circular holes help reduce the weight of the mixing element 2 and may, to some extent, reduce the overall pressure drop when the fluid passes through.

[0035] The opening angle between the two straight sections The opening angle, which can be any one of 30°, 45°, 60°, 75°, and 90°, is a key parameter determining the intensity of fluid disturbance caused by the mixing element 2. A smaller opening angle (such as 30°) will cause the fluid to be deflected more violently, producing stronger eddies and mixing effects, but may be accompanied by a higher pressure drop. A larger opening angle (such as 90°) provides relatively mild disturbance and lower pressure drop, but the mixing intensity may be slightly reduced. By selecting different opening angles, the performance of the mixing element 2 can be precisely controlled according to specific operating conditions (such as fluid viscosity, flow rate, required mixing intensity, and allowable pressure drop) to achieve optimal heat transfer and mixing effects. This angle can be controlled during manufacturing through precise assembly or integral molding.

[0036] like Figure 1-2As shown, this application further proposes that the number of mixing elements 2 is 6, which are arranged at intervals along the axial direction of the main pipe 1 and are centrally symmetrically distributed with respect to the central axis of the main pipe 1; adjacent mixing elements 2 are rotated out of each other, and the out-of-place angle is any one of 30°, 45°, 60° and 90°.

[0037] Specifically, the number of mixing elements 2 is six. This number is optimized to ensure sufficient mixing while effectively controlling pressure loss as the fluid passes through the main pipe 1. In practical applications, the number of mixing elements 2 can be adjusted according to the length and diameter of the main pipe 1 and the required mixing intensity; for example, it can be set to four, eight, or ten. However, six is ​​considered an efficient and balanced configuration in this embodiment. The mixing elements 2 are spaced apart along the axial direction of the main pipe 1. This arrangement ensures that the fluid is continuously disturbed by the mixing elements 2 throughout its passage through the main pipe 1, thereby achieving a gradual mixing effect. The spacing can be uniform to ensure the continuity of mixing intensity, or non-uniform to adapt to the mixing needs of different fluid regions.

[0038] The mixing element 2 is centrally symmetrically distributed around the central axis of the main pipe 1. This symmetrical distribution helps maintain uniform fluid flow across the pipe cross-section, avoiding flow deviation or local stagnation caused by asymmetrical arrangement. It ensures that the disturbance effect of the mixing element 2 on the fluid can be uniformly applied across the entire fluid cross-section, thereby improving overall mixing efficiency and heat transfer uniformity.

[0039] Adjacent hybrid elements 2 have rotational misalignment, misalignment angle The angles can be any one of 30°, 45°, 60°, and 90°. Rotational misalignment is a key technical feature for enhancing radial mixing of fluids. By causing adjacent mixing elements 2 to deflect at a certain angle in the axial direction, the laminar boundary layer of the fluid can be effectively broken, generating more complex helical flows and vortices, thereby promoting thorough mixing of the fluid in the radial direction. The listed misalignment angles of 30°, 45°, 60°, and 90° are effective angles that have been experimentally verified. They can provide good mixing effects in different application scenarios. For example, a 90° misalignment can significantly change the flow direction of the fluid after passing through each mixing element 2, thereby maximizing the mixing effect.

[0040] Preferred, such as Figure 1 As shown, the ratio of the length to the diameter of the main pipe 1 is 31:2. Here, the pipe length refers to the effective heat exchange length of the main pipe 1, that is, the actual distance the fluid travels within it for heat exchange and flow. Pipe diameter refers to the inner diameter of main pipe 1. D .

[0041] Preferred, such as Figure 2 As shown, the length of the two straight plate segments 21 in the hybrid element 2 is... b :Width a :high Both are 40:10:1.

[0042] Preferably, the length ratio of the mixing section with mixing elements to the non-mixing section without mixing elements on the main pipeline 1 is 21:10. Here, the mixing section with mixing elements on the main pipeline 1 refers to the area in the main pipeline 1 where multiple mixing elements 2 are fixed. This mixing section is the core area for achieving fluid disturbance, promoting turbulent mixing, and enhancing convective heat transfer. Within this region, the flow direction and velocity distribution of the fluid change significantly as it passes through the mixing element 2, thereby breaking down the boundary layer and improving heat transfer efficiency. The non-mixing section, without any mixing element 2, refers to the area in the main pipe 1 where no mixing element 2 is installed. The non-mixing section is typically used for fluid introduction, export, or as a stabilization zone before the fluid enters or leaves the mixing section. In the non-mixing section, the fluid flows relatively smoothly, its main function being to reduce fluid resistance and provide necessary connections or buffer space for the system. A large portion of the main pipe 1 is designed as a mixing section to fully utilize the heat transfer enhancement effect of the mixing element 2. Simultaneously, a certain length of non-mixing section is reserved to balance the overall fluid resistance and avoid excessive system energy consumption due to excessive mixing element 2. This proportion is usually determined based on a comprehensive consideration of factors such as fluid dynamics, heat transfer efficiency, and system pressure drop, aiming to achieve an optimal balance between heat transfer performance and operational economy.

[0043] To verify the technical effect of the present invention, the flow field and heat transfer performance of the water-cooled wall pipe coated with the high heat transfer and wear-resistant coating of the present invention were simulated and analyzed. The simulation results are as follows: Figure 3 and Figure 4 As shown in Table 1, the preferred parameter settings for the main pipeline and mixing element are as follows: Table 1 Figure 3 This displays a two-dimensional streamline distribution diagram of the fluid within the main pipe. x (This represents the distance between the main pipeline inlet and the current axial section position). As can be seen from the figure, in (a) x At a diameter of 105mm, the main channel exhibits a large primary vortex, with two smaller vortices pointing in the same direction in the core region. (b) x When the diameter is 122.5 mm, the size of the two vortices in the main channel increases to some extent when passing through the mixing element. (c) xWhen the diameter is 140mm, the diameter of the circular holes on the straight plate section gradually increases, increasing the mixing effect on the fluid. Therefore, two relatively obvious unidirectional vortices are formed at the intersection of the straight plate sections, and the trajectory of the two-dimensional streamlines is not a complete circle, also affecting the area near the wall. (d) x At a diameter of 157.5 mm, the vortex in the core region remains essentially unchanged. (d) x At a diameter of 175 mm, the fluid underwent one cycle within the pipe. The vortex size in the main channel increased, and the flow near the wall became more turbulent due to the turbulence from the mixing element, thus better disrupting the boundary layer. However, in (f)... x At a diameter of 192.5 mm, due to the misalignment angle between adjacent mixing elements, the two vortices in the core region merge into a single mainstream vortex, forming two relatively distinct pairs of forced vortices at the tip of the straight section near the wall. (g) x =210mm and (h) x At 227.5 mm, the co-directional vortex formed by the fluid near the mixing element also shows little change from the same position in the previous cycle. In (i) x When the diameter is 245mm, the vortex size in the main channel increases to be similar to the pipe diameter, and the two unidirectional vortices in the core area begin to mix.

[0044] Figure 4 The figure shows the overall three-dimensional spiral streamlines of the fluid within the main pipe, the flow trajectory of fluid particles, and the velocity distribution at different axial cross sections. As can be seen from the figure, the flow of fluid particles is divided by the straight plate section, but the fluid passing through the surface of the straight plate section also perforates through the circular holes, making the fluid flow more turbulent and resulting in better compression and disruption of the boundary layer. Analysis of the velocity distribution at different axial cross sections shows that the overall velocity distribution within the pipe is more uniform, and the high-speed region is larger, exhibiting an overall axisymmetric distribution. The low-speed region is somewhat reduced, but it is mainly distributed near the straight plate section, while the high-speed region mainly appears near the main flow channel and the inner wall surface. (b) x Within a 140mm section, the presence of the circular holes results in a more uniform velocity throughout the pipe after the flow distribution effect of the straight section, and a larger high-speed region. (c) x When the diameter is 175mm, the high-speed zone has already been mixed, and a large high-speed zone has basically been generated in the main channel, with a higher speed.

[0045] The combined effect of these flow field characteristics results in a large velocity gradient generated by vortex motion in the core region, which helps reduce fluid viscous drag; while the continuous disruption of the boundary layer in the near-wall region significantly enhances the intensity of turbulent heat transfer. Simulation data show that this structure effectively controls flow resistance while enhancing heat transfer, achieving high-efficiency heat transfer with low power consumption, and its overall performance evaluation index (PEC) is superior to that of conventional structures.

[0046] The simulation results above fully verify that the design of this invention, which combines perforated blade-type intercalation elements, specific hybrid element arrangement (such as staggered angles), and high heat transfer and wear-resistant coating, can synergistically optimize the flow field structure, disrupt the thermal boundary layer, improve heat transfer efficiency and uniformity, and reduce flow pressure drop, thereby achieving the technical objectives of extending the life of water-cooled walls, improving boiler thermal efficiency, and enhancing operational economy.

[0047] Furthermore, the present invention also provides a method for preparing a water-cooled wall pipe coated with a high heat transfer and wear-resistant coating, comprising the following steps: S1. Pretreatment of main pipe and mixing element: The mixing element is printed by 3D printing technology. The main pipe and the mixing element are placed in the cleaning agent and heated to 60°C for 30 minutes. After soaking, they are rinsed with clean water until there is no obvious cleaning agent residue. Then they are air-dried and then dried.

[0048] S2. Preparation of the substrate for the first coating: At room temperature, 1.7g of bisphenol A diglycidyl ether was preheated for 30min, and then 1.08g of neopentyl glycol diglycidyl ether, 2g of polyetheramine T-403, 0.5g of curing agent and 2mL of ethyl acetate were added and magnetically stirred for 30min until uniformly mixed. Then, 0.06g of nano ZrO2, 2mL of ethyl acetate and 0.8g of polyvinyl alcohol were added to the resulting mixed solution and magnetically stirred to obtain the substrate coating. S3. Preparation of the first coating: The obtained base coating is mixed with 0.79g of graphene under mechanical mixing at 100 r / min for 30 minutes; then, 0.05g of curing agent is added to the mixture and stirred at 300 r / min for 1 minute; then, the gel coat graphene composite coating (i.e., the first coating) is obtained. S4. Preparation of the second coating component A: Mix 1g TiO2 and 1g nano ZrO2, then add to 20mL ethyl acetate and ultrasonically mix for 30min. After mixing, add 0.5g cyclomethylsiloxane and magnetically stir for 30min. Then add 0.1g cyclomethylsiloxane, 0.01g curing agent, and 0.1g 1H,1H,2H,2H. Perfluorodecyltriethoxysilane was magnetically stirred for 60 min to obtain component A. S5. Preparation of the second coating component B: 20g of multi-walled carbon nanotubes were added to a mixture of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1 and mixed evenly. The mixture was heated and stirred at a constant temperature of 60℃ for 2 hours. After cooling to room temperature, the mixture was diluted with distilled water and filtered. The acidified multi-walled carbon nanotubes were washed with water and vacuum filtered until the filtrate was neutral to obtain component B. S6. Preparation of the second coating: Mix 100 mL of deionized water, component B, and 0.5 g of cyclomethylsiloxane, then heat in a constant temperature water bath and stir for 5 min. Disperse by ultrasonication for 30 min, add to component A and continue ultrasonic dispersion for 30 min to obtain the second coating. S7. Spraying the inner wall of the main pipeline and the surface of the mixing element: After spraying the first coating on the inner wall of the main pipeline and the surface of the mixing element with an airless spraying device, cure at 70°C for 4 hours, and then spray the second coating and cure at 70°C for 4 hours. S8. Spraying the outer wall of the main pipeline: After spraying the first coating layer onto the outer wall of the main pipeline using an airless spraying device, cure it at 70°C for 4 hours. After spraying the second coating layer, cure it at 70°C for 4 hours. S9. Sealing: Connect the main pipeline to the mixing element using sealing technology, and check for air tightness and water tightness.

[0049] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A water-cooled wall pipe coated with a high heat transfer and wear-resistant coating, characterized in that, include: Main pipe (1) and multiple mixing elements (2); Each of the mixing elements (2) is fixed to the inner wall of the main pipe (1); the inner and outer walls of the main pipe (1) and the surface of the mixing elements (2) are coated with a high heat transfer and wear-resistant coating. The high heat transfer and wear-resistant coating includes a first coating and a second coating arranged sequentially from the inside to the outside.

2. The water-cooled wall pipe according to claim 1, characterized in that, The first coating is composed of bisphenol A diglycidyl ether, neopentyl glycol diglycidyl ether, polyetheramine, curing agent, nano ZrO2, graphene, polyvinyl alcohol, and ethyl acetate.

3. The water-cooled wall pipe according to claim 1, characterized in that, The second coating consists of nano-ZrO2, TiO2, cyclomethylsiloxane, 1H,1H,2H,2H It consists of perfluorodecyltriethoxysilane, curing agent, ethyl acetate, multi-walled carbon nanotubes, a mixture of concentrated sulfuric acid and concentrated nitric acid, and deionized water.

4. The water-cooled wall pipe according to claim 1, characterized in that, Each of the hybrid elements (2) includes two cross-connected straight plate segments (21); each straight plate segment is leaf-shaped and has a circular hole; the opening angle between the two straight plate segments is any one of 30°, 45°, 60°, 75° and 90°.

5. The water-cooled wall pipe according to claim 4, characterized in that, The number of mixing elements (2) is 6, which are arranged at intervals along the axial direction of the main pipe (1) and are centrally symmetrical about the central axis of the main pipe (1); adjacent mixing elements (2) are rotated out of each other, and the out-of-place angle is any one of 30°, 45°, 60° and 90°.

6. The water-cooled wall pipe according to claim 1, characterized in that, The ratio of the length to the diameter of the main pipe (1) is 31:

2.

7. The water-cooled wall pipe according to claim 1, characterized in that, The length:width:height ratio of the two straight sections (21) in the hybrid element (2) is 40:10:

1.

8. The water-cooled wall pipe according to claim 1, characterized in that, The length ratio of the mixing section with mixing elements on the main pipeline (1) to the non-mixing section without mixing elements is 21:

10.

9. A method for preparing a water-cooled wall pipe as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Print the hybrid component using 3D printing technology. Place the main pipe and the hybrid component into the cleaning agent and heat it to 60°C for 30 minutes. After soaking, rinse with clean water until there is no obvious cleaning agent residue. Then air dry and then dry. S2. At room temperature, 1.7g of bisphenol A diglycidyl ether was preheated for 30 minutes, and then 1.08g of neopentyl glycol diglycidyl ether, 2g of polyetheramine T-403, 0.5g of curing agent and 2mL of ethyl acetate were added and magnetically stirred for 30 minutes until the mixture was homogeneous. Then, 0.06g of nano ZrO2, 2mL of ethyl acetate and 0.8g of polyvinyl alcohol were added to the resulting mixture and magnetically stirred to obtain the base coating. S3. Mix the obtained base coating with 0.79 g of graphene under mechanical mixing at 100 r / min for 30 minutes; Then, add 0.05g of curing agent to the mixture and stir at 300 r / min for 1 minute; Then, the first coating is obtained; S4. Mix 1g TiO2 and 1g nano ZrO2, then add to 20mL ethyl acetate and sonicate for 30min. After mixing, add 0.5g cyclomethylsiloxane and stir magnetically for 30min. Then add 0.1g cyclomethylsiloxane, 0.01g curing agent, and 0.1g 1H,1H,2H,2H. Perfluorodecyltriethoxysilane was magnetically stirred for 60 min to obtain component A. S5. Add 20g of multi-walled carbon nanotubes to a mixture of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1 and mix well. Heat and stir at a constant temperature of 60℃ for 2 hours to acidify. Cool to room temperature, dilute with distilled water and filter. Wash the acidified multi-walled carbon nanotubes with water and vacuum filter until the filtrate is neutral to obtain component B. S6. Mix 100mL of deionized water, component B, and 0.5g of cyclomethylsiloxane, then heat in a constant temperature water bath and stir for 5min. Ultrasonically disperse for 30min, then add to component A and continue ultrasonic dispersion for 30min to obtain the second coating. S7. Spraying the inner wall of the main pipeline and the surface of the mixing element: After spraying the first coating on the inner wall of the main pipeline and the surface of the mixing element with an airless spraying device, cure at 70°C for 4 hours, and then spray the second coating and cure at 70°C for 4 hours. S8. After applying the first coating to the outer wall of the main pipeline using an airless spraying device, cure it at 70°C for 4 hours. After applying the second coating, cure it at 70°C for 4 hours. S9. Connect the main pipeline to the mixing element using sealing technology, and check the airtightness and watertightness.

Images