High-temperature-resistant steam turbine thermal insulation layer high-temperature fabric cloth and preparation process thereof

Abstract

The application discloses a kind of high-temperature fabric cloth of high-temperature steam turbine insulation layer and preparation process thereof, belong to high-temperature steam turbine insulation layer high-temperature fabric cloth technical field, the process includes the following steps: high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, alkali metal oxide are weighed and mixed according to formula, input high-temperature smelting kiln, melt into homogeneous glass liquid under 1500-1600 °C, and glass liquid is introduced into platinum rhodium alloy sieve plate, and the continuous glass fiber monofilament of 3-9 microns in diameter is drawn out.The application is adapted to the temperature response characteristics of functional sizing agent by temperature gradient adaptive sizing design, so that the fabric realizes dynamic enhancement of insulation performance as temperature rises, has excellent thermal insulation, mechanical stability, and raw material cost is controllable, adapts to the insulation needs of different high-temperature working conditions of steam turbine, improves the practicability and cost performance of insulation fabric.

Description

Technical Field

[0001] This invention relates to the field of high-temperature resistant steam turbine insulation layer high-temperature fabric technology, specifically, to a high-temperature resistant steam turbine insulation layer high-temperature fabric and its preparation process. Background Technology

[0002] As a core power equipment, steam turbines often operate under gradient high-temperature conditions ranging from 300 to 900°C. The thermal insulation performance, temperature adaptability, and structural stability of the insulation layer fabric directly affect the equipment's operating efficiency and safety. Existing steam turbine insulation layer fabrics mostly adopt a single-coating design, which cannot dynamically enhance the thermal insulation performance as the operating temperature rises. At high temperatures, they are prone to problems such as insufficient insulation layer density and high heat conduction efficiency, and have poor heat radiation and heat convection blocking effects, making it difficult to adapt to the high-temperature gradient operation requirements of steam turbines. Therefore, there is an urgent need to develop a high-temperature insulation layer fabric and its preparation process that is adaptable to the gradient high temperature of steam turbines, can dynamically enhance the insulation effect, and is cost-effective.

[0003] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0004] To address the problems in related technologies, this invention proposes a high-temperature resistant steam turbine insulation layer fabric and its preparation process, in order to overcome the technical problem of poor insulation performance in existing related technologies.

[0005] Therefore, the specific technical solution adopted by the present invention is as follows: A high-temperature resistant fabric for steam turbine insulation layer and its preparation process, the process including the following steps: S1. Weigh and mix high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides according to the formula, put them into a high-temperature melting furnace, melt them into a uniform glass liquid at 1500–1600°C, and then introduce the glass liquid into a platinum-rhodium alloy stencil to draw out continuous glass fiber monofilaments with a diameter of 3–9 micrometers. S2. Prepare thermal insulation slurry by mixing polysilazane prepolymer, nano-alumina powder, xylene, silane coupling agent, and dispersant; S3. Prepare the sizing agent, and determine the amount of thermal insulation slurry to be added according to the working temperature range of the steam turbine. Then mix the thermal insulation slurry and the sizing agent to form a uniform functional sizing agent. S4. The drawn glass fiber monofilaments are evenly coated with a functional sizing agent by spraying. After curing, multiple monofilaments are bundled into a raw yarn and twisted by a twisting machine. S5. Using an air-jet loom, the twisted yarn is woven into a fabric as the base material for the insulation layer. The woven fabric is then heat-set and finally tested for thickness, density, thermal conductivity, and high-temperature expansion performance.

[0006] In a preferred embodiment, the steps of weighing and mixing high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides according to the formula, adding them to a high-temperature melting furnace, melting them into a uniform glass melt at 1500–1600°C, and then guiding the glass melt into a platinum-rhodium alloy stencil to draw out continuous glass fiber monofilaments with a diameter of 3–9 micrometers include the following steps: S11. Weigh the high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides according to the formula, and then put them into a high-efficiency mixer to stir them thoroughly to ensure that each component is evenly distributed and form a batch material. S12. The uniformly mixed batch is continuously fed into a high-temperature melting furnace through a feeder and melted at a temperature of 1500–1600°C to completely transform it into a homogeneous glass melt. During this process, high-temperature clarification is completed to remove air bubbles from the melt. S13. The homogenized and clarified molten glass is led out through a flow hole or channel and enters a feeding channel with a precision temperature control system to adjust and stabilize the temperature of the molten glass at 1250°C. S14. The molten glass is introduced into a stencil made of platinum-rhodium alloy. A high-speed rotating wire drawing machine drum is used to draw the thin stream of molten glass flowing out of the stencil downwards at high speed. During the drawing process, forced air cooling is used to rapidly solidify it, forming continuous glass fiber monofilaments in the range of 3–9 micrometers in diameter.

[0007] Below the sprue are precisely arranged hundreds to thousands of micro-holes. Under stable pressure and temperature, the molten glass flows out naturally from the sprue by its own gravity.

[0008] In a preferred embodiment, the preparation of the thermal insulation slurry by the following steps includes: preparing the polysilazane prepolymer, nano-alumina powder, xylene, silane coupling agent, and dispersant. S21. Check and prepare the required raw materials to ensure the purity and dryness of the polysilazane prepolymer, nano alumina powder, xylene, silane coupling agent and dispersant. At the same time, introduce nitrogen into the reaction vessel to replace the internal air and establish an inert protective environment. S22. Under continuous nitrogen protection, add the polysilazane prepolymer and xylene solvent to a reactor equipped with a stirrer and temperature control device, control the temperature at 25-30°C, and stir at 300-500 rpm for 20-30 minutes to fully mix the two and form a uniform and transparent matrix solution. S23. Add nano-alumina powder, silane coupling agent and dispersant to the matrix solution in sequence, increase the stirring speed to 1500-2000 rpm, and continue to stir with strong shear for 30-40 minutes at this speed to initially wet and disperse the nano-powder in the solution to form a suspension slurry. S24. Transfer the initially dispersed slurry to the grinding jar of a planetary ball mill or sand mill, add zirconia grinding balls, and set the milling speed to 300-400 rpm for 6-8 hours. Ball milling can completely break up the agglomeration of nanoparticles and achieve uniform nanoscale dispersion of fillers in slurry; S25. Filter the ball-milled slurry through a 400-600 mesh precision sieve to remove trace large particles or impurities from the grinding process. Then transfer the filtered slurry to a vacuum degassing tank and let it stand or stir slowly under low vacuum for 10-20 minutes to remove air bubbles entrained in the slurry. S26. Fill the defoamed, uniform, and stable thermal insulation slurry into a sealed, opaque container, fill it with a small amount of nitrogen, seal it, affix a label indicating the ingredients, batch number, and preparation date, and store it in a cool, dry environment.

[0009] In a preferred embodiment, the preparation of the sizing agent, determining the amount of thermal insulation slurry to be added based on the operating temperature range of the steam turbine, and then mixing the thermal insulation slurry and the sizing agent to form a uniform functional sizing agent includes the following steps: S31. Prepare film-forming agent, lubricant, coupling agent, toughening agent, antistatic agent, and wetting agent. Then, hydrolyze the coupling agent in deionized water at room temperature for 30-60 minutes. Subsequently, add the film-forming agent, lubricant, toughening agent, antistatic agent, and wetting agent in sequence with stirring. Heat the mixture to 50-80°C and stir continuously for 20-60 minutes to ensure that each component is fully emulsified and dispersed. Finally, adjust the pH value and filter to remove impurities to obtain a uniform and stable sizing agent emulsion. S32. Determine the amount of thermal insulation grout to be added based on the operating temperature range of the steam turbine; S33. Transfer 80% of the sizing agent to a mixing tank with constant temperature and stirring function, turn on the stirring at 200–400 rpm, and set the water temperature of the mixing tank jacket at 40–50°C to improve the fluidity of the sizing agent under gentle heating. S34. After all the thermal insulation slurry is added, increase the stirring speed to 1200–1500 rpm and start the homogenizer. Under this condition, continue to stir with strong shear for 30–45 minutes to ensure that the thermal insulation slurry and the sizing agent are completely and uniformly miscible to form a uniform and stable composite system. S35. Slowly add the remaining 20% ​​of the sizing agent to the mixing tank, adjust the overall viscosity and solid content, and add defoamer at the same time. Adjust the stirring speed back to 300–500 rpm and continue stirring for 15–20 minutes to obtain the functional sizing agent. S36. Filter the functional sizing agent through a 200-300 mesh filter or filter bag to remove impurities generated during the mixing process. Transfer the filtered slurry to a clean storage tank and let it stand and mature at room temperature for 8 hours.

[0010] In a preferred embodiment, determining the amount of thermal insulation slurry to be added based on the operating temperature range of the steam turbine includes the following steps: S321. Divide the operating temperature range of the steam turbine into three zones: 300–500°C for low temperature, 500–700°C for medium temperature, and 700–900°C for high temperature; and add 8–12 parts of insulation slurry for the low temperature zone; 12–15 parts for the medium temperature zone; and 15–20 parts for the high temperature zone.

[0011] In a preferred embodiment, the process of uniformly coating the drawn glass fiber monofilaments with a functional sizing agent by spraying, curing the agent, bundling multiple monofilaments into a raw yarn, and twisting it using a twisting machine includes the following steps: S41. Guide the continuously running glass fiber monofilament after drawing into a sealed spraying chamber. Apply the prepared functional sizing agent evenly to the fiber surface in the form of atomization through a precision nozzle. By adjusting the spraying pressure, flow rate and fiber feeding speed, ensure that a complete, continuous and controllable coating layer is formed on the surface of each monofilament. S42. Place the coated glass fiber into a segmented temperature-controlled drying channel and keep it at 200–250°C for 1–2 minutes to allow the solvent in the coating to evaporate rapidly, while the organic components undergo preliminary cross-linking and curing, thereby forming a stable and functional film on the fiber surface. S43. The solidified monofilaments are precisely combined on the bundler, and neatly arranged and merged into a loosely structured, untwisted fiber bundle through the yarn guide eye. S44. The combined raw yarn is introduced into the twisting machine, and the yarn is twisted by the rotation of the spindle, so that the fibers are interlocked. The twisted yarn is then wound onto a standard yarn tube or bobbin with constant tension to form a regular yarn package.

[0012] In a preferred embodiment, the process of using an air-jet loom to weave the twisted yarn into a fabric as the base material for the insulation layer, and then performing heat setting treatment on the woven fabric, followed by testing its thickness, density, thermal conductivity, and high-temperature expansion properties, includes the following steps: S51. Place the twisted yarn bobbin on the warping frame and use the warping machine to evenly wind the yarn onto the warp beam according to the designed arrangement, width and tension. S52. Install the prepared warp beams and weft yarn bobbins onto the air-jet loom. Based on the designed fabric structure and specifications, set the loom's process parameters such as weft insertion air pressure, shedding time, and weft striking force. S53. The air jet loom uses high-speed airflow ejected from the main nozzle and the relay nozzle to introduce the weft yarn into the shed formed by the warp yarn opening, and pushes the weft yarn towards the weft opening through the beating motion of the reed, so that the warp and weft yarns interweave according to the preset structure to form a fabric. S54. The woven continuous fabric is wound onto the unwinding roll to form a greige roll. The greige is then subjected to a preliminary inspection to check for defects such as broken warp, broken weft, or uneven density. S55. Place the blank in a heat setting machine to eliminate internal stress, stabilize the fabric size, and initially cure the functional coating. S56. For the treated fabric, use a fabric thickness gauge and balance to measure its thickness and mass per unit area at multiple points, and calculate its bulk density to ensure that its basic physical properties meet the design specifications; use a flat thermal conductivity meter or similar heat flow meter to measure the thermal conductivity of the fabric at a set standard temperature to evaluate its basic thermal insulation performance; place the fabric sample in a programmable temperature-controlled high-temperature box furnace to simulate its target working temperature range for heating, and quantify its volume expansion rate at high temperature by recording its size changes with temperature and time to verify the effectiveness and stability of its intermediate coating function; S57. Summarize all test data, evaluate the overall performance of the fabric, roll or fold qualified products into specified lengths, and pack them in moisture-proof packaging, affixing labels containing batch number, specifications and test results.

[0013] A high-temperature resistant fabric for steam turbine insulation layers, wherein the fabric is prepared using any of the above-described high-temperature resistant fabrics and their manufacturing process, including the following raw materials: The raw materials for glass fiber monofilaments include high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides, among which the alkali metal oxides are Na2O+K2O. The raw materials for thermal insulation mortar include polysilazane prepolymer, nano alumina powder, xylene, silane coupling agent, and dispersant, wherein the dispersant is polyvinylpyrrolidone; The raw materials for the sizing agent include film-forming agents, lubricants, coupling agents, toughening agents, antistatic agents, and wetting agents; among which the film-forming agent is epoxy resin, the lubricant is polyethylene wax emulsion, the coupling agent is KH-550, the toughening agent is acrylate copolymer, the antistatic agent is polyether compound, and the wetting agent is polyether modified siloxane. As a preferred embodiment, the raw materials for glass fiber monofilaments include high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides, with 52-56 parts of high-purity quartz sand, 12-16 parts of alumina, 16-25 parts of calcium oxide, 8-13 parts of boric acid, 0-5 parts of magnesium oxide, and 0-2 parts of alkali metal oxides. The raw materials for thermal insulation mortar include polysilazane prepolymer, nano alumina powder, xylene, silane coupling agent, and dispersant, with 40–50 parts of polysilazane prepolymer, 20–30 parts of nano alumina powder, 25–35 parts of xylene, 1–2 parts of silane coupling agent, and 0.5–1 part of dispersant. The raw materials for the sizing agent include film-forming agents, lubricants, coupling agents, toughening agents, antistatic agents, and wetting agents; and the film-forming agent is 40-80 parts, the lubricant is 5-20 parts, the coupling agent is 2-15 parts, the toughening agent is 1-21 parts, the antistatic agent is 7-12 parts, and the wetting agent is 1-6 parts.

[0014] The beneficial effects of this invention are as follows: 1. The functional sizing agent prepared by this invention can undergo targeted physical and chemical changes as the operating temperature of the steam turbine increases, thereby dynamically enhancing the insulation effect. When the temperature rises, the molecular thermal motion intensifies, which on the one hand promotes the cross-linking and expansion reaction of the ceramic precursor in the sizing agent, widens the gap between molecules and extends them to the outer layer of the fiber, forming a thicker, fluffier and more porous heat-insulating ceramic layer on the surface of the glass fiber fabric, effectively increasing the heat transfer path and reducing the heat conduction efficiency. On the other hand, the stable dispersion characteristics of nano-alumina powder at high temperature, combined with the dense structure after the ceramic transformation of polysilazane, will form a continuous heat-insulating barrier on the surface of the fabric, blocking the transfer of heat radiation and heat convection. At the same time, the functional sizing agent is tightly adhered to the surface of the glass fiber monofilament by spraying and curing. The overall fabric structure formed after twisting and weaving allows this temperature-responsive expansion and outer layer aggregation effect to occur simultaneously between the warp and weft yarns, so that the insulation performance of the insulation fabric can be progressively enhanced as the temperature rises from the fiber monofilament to the overall fabric layer, which is suitable for the heat insulation requirements of the steam turbine under high temperature conditions.

[0015] 2. This invention precisely matches insulation requirements by adding different amounts of insulation slurry according to the operating temperature ranges of the steam turbine (300–500°C, 500–700°C, and 700–900°C). Higher steam turbine operating temperatures result in greater heat flux density, requiring a corresponding increase in the amount of insulation slurry added. This allows for the formation of a coating of appropriate thickness on the fiber surface. The resulting high-temperature ceramization creates a thicker insulation barrier with a richer pore structure, effectively blocking heat transfer at higher temperatures. This avoids problems such as insufficient slurry leading to poor insulation performance, coating powdering, and peeling. Furthermore, it ensures the overall mechanical properties of the fabric. In low-temperature ranges, a small amount of slurry is sufficient for effective insulation; excessive amounts result in an overly thick coating, reducing fiber cohesion. In medium- and high-temperature ranges, the amount of slurry added should be increased as needed. Simultaneously controlling the upper limit can prevent excessive decline in fabric strength retention and coating adhesion, ensuring that the insulation cloth has good structural stability and durability under the vibration and high temperature environment of the steam turbine. Finally, it can also achieve the optimal cost configuration. The amount of slurry added in each temperature range is set within the effective range of performance improvement. If it is below the lower limit, the functionality will be insufficient, and if it is above the upper limit, the performance improvement will enter a plateau period with extremely low marginal effect and unnecessary consumption of slurry raw materials. Quantitative addition according to the temperature gradient can maximize the control of raw material costs and production process difficulty while meeting the insulation requirements of different working conditions, thereby improving the cost performance and market applicability of the product. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of a high-temperature fabric preparation process for a high-temperature resistant steam turbine insulation layer according to an embodiment of the present invention. Detailed Implementation

[0018] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0019] According to an embodiment of the present invention, a high-temperature resistant steam turbine insulation layer high-temperature fabric and its preparation process are provided.

[0020] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figure 1 As shown, a process for preparing a high-temperature resistant steam turbine insulation layer fabric according to an embodiment of the present invention includes the following steps: S1. Weigh and mix high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides according to the formula, put them into a high-temperature melting furnace, melt them into a uniform glass liquid at 1500–1600°C, and then introduce the glass liquid into a platinum-rhodium alloy stencil to draw out continuous glass fiber monofilaments with a diameter of 3–9 micrometers. Further, high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides are weighed and mixed according to the formula, and then added to a high-temperature melting furnace. The mixture is melted into a homogeneous glass melt at 1500–1600°C, and the glass melt is then introduced into a platinum-rhodium alloy baffle plate to draw out continuous glass fiber monofilaments with a diameter of 3–9 micrometers. This process includes the following steps: S11. Weigh the high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides according to the formula, and then put them into a high-efficiency mixer to stir them thoroughly to ensure that each component is evenly distributed and form a batch material. S12. The uniformly mixed batch is continuously fed into a high-temperature melting furnace through a feeder and melted at a temperature of 1500–1600°C to completely transform it into a homogeneous glass melt. During this process, high-temperature clarification is completed to remove air bubbles from the melt. S13. The homogenized and clarified molten glass is led out through a flow hole or channel and enters a feeding channel with a precision temperature control system to adjust and stabilize the temperature of the molten glass at 1250°C. S14. The molten glass is introduced into a stencil made of platinum-rhodium alloy. A high-speed rotating wire drawing machine drum is used to draw the thin stream of molten glass flowing out of the stencil downwards at high speed. During the drawing process, forced air cooling is used to rapidly solidify it, forming continuous glass fiber monofilaments in the range of 3–9 micrometers in diameter. S2. Prepare thermal insulation slurry by mixing polysilazane prepolymer, nano-alumina powder, xylene, silane coupling agent, and dispersant; Furthermore, the preparation of the thermal insulation slurry by using polysilazane prepolymer, nano-alumina powder, xylene, silane coupling agent, and dispersant includes the following steps: S21. Check and prepare the required raw materials to ensure the purity and dryness of the polysilazane prepolymer, nano alumina powder, xylene, silane coupling agent and dispersant. At the same time, introduce nitrogen into the reaction vessel to replace the internal air and establish an inert protective environment. It should be noted that, to ensure the stability of the slurry intermediate and the controllability of the subsequent high-temperature ceramic transformation, each raw material must meet the following standards: the purity of the polysilazane prepolymer should be ≥98%, and the moisture content should be <0.1% to prevent premature cross-linking or decomposition under the influence of moisture; the purity of the nano-alumina powder should be ≥99.5%, with an average particle size of 20-50nm and a moisture content of <0.5% to ensure its dispersibility in the slurry and the density of the final insulation layer; the xylene solvent must be of analytical grade, with a purity ≥99.5% and a moisture content of <0.05% to avoid introducing impurities that affect the stability of the slurry; the purity of the silane coupling agent should be ≥98%, and it must be sealed and stored before use to prevent moisture absorption; the dispersant, i.e., polyvinylpyrrolidone, must meet the specifications for its K value and have a moisture content of <1%. It is recommended that all solid raw materials be vacuum dried at 110°C for more than 2 hours before use, while liquid raw materials must be dehydrated using molecular sieves. This is the basis for controlling the storage stability of the slurry, the uniformity of coating, and the performance of the final expanded insulation layer. S22. Under continuous nitrogen protection, add the polysilazane prepolymer and xylene solvent to a reactor equipped with a stirrer and temperature control device, control the temperature at 25-30°C, and stir at 300-500 rpm for 20-30 minutes to fully mix the two and form a uniform and transparent matrix solution. S23. Add nano-alumina powder, silane coupling agent and dispersant to the matrix solution in sequence, increase the stirring speed to 1500-2000 rpm, and continue to stir with strong shear for 30-40 minutes at this speed to initially wet and disperse the nano-powder in the solution to form a suspension slurry. S24. Transfer the initially dispersed slurry to the grinding jar of a planetary ball mill or sand mill, add zirconia grinding balls, and set the milling speed to 300-400 rpm for 6-8 hours. S25. Filter the ball-milled slurry through a 400-600 mesh precision sieve to remove trace large particles or impurities from the grinding process. Then transfer the filtered slurry to a vacuum degassing tank and let it stand or stir slowly under low vacuum for 10-20 minutes to remove air bubbles entrained in the slurry. S26. Fill the defoamed, homogeneous, and stable thermal insulation slurry into a sealed, opaque container, fill it with a small amount of nitrogen, seal it, affix a label indicating the ingredients, batch number, and preparation date, and store it in a cool, dry environment. S3. Prepare the sizing agent, and determine the amount of thermal insulation slurry to be added according to the working temperature range of the steam turbine. Then mix the thermal insulation slurry and the sizing agent to form a uniform functional sizing agent. Further, the preparation of the sizing agent, and the determination of the amount of thermal insulation slurry to be added based on the operating temperature range of the steam turbine, followed by the mixing of the thermal insulation slurry and the sizing agent to form a uniform functional sizing agent, include the following steps: S31. Prepare film-forming agent, lubricant, coupling agent, toughening agent, antistatic agent, and wetting agent. Then, hydrolyze the coupling agent in deionized water at room temperature for 30-60 minutes. Subsequently, add the film-forming agent, lubricant, toughening agent, antistatic agent, and wetting agent in sequence with stirring. Heat the mixture to 50-80°C and stir continuously for 20-60 minutes to ensure that each component is fully emulsified and dispersed. Finally, adjust the pH value and filter to remove impurities to obtain a uniform and stable sizing agent emulsion. S32. Determine the amount of thermal insulation grout to be added based on the operating temperature range of the steam turbine; Furthermore, S321 divides the operating temperature range of the steam turbine into three zones: 300–500°C for low temperature, 500–700°C for medium temperature, and 700–900°C for high temperature; and the amount of insulation slurry added in the low temperature zone is 8–12 parts; the amount of insulation slurry added in the medium temperature zone is 12–15 parts; and the amount of insulation slurry added in the high temperature zone is 15–20 parts.

[0021] It should be noted that if a fixed amount of insulation slurry is added for different operating temperature ranges of the steam turbine, it will be difficult to match the heat insulation requirements of the steam turbine under different operating conditions with the comprehensive performance requirements of the fabric; this will cause many problems. The higher the operating temperature of the steam turbine, the greater its heat flux density, and the higher the requirements for the heat insulation performance of the insulation layer. Therefore, for higher operating temperature ranges, increasing the amount of insulation slurry added means that a thicker coating is formed on the fiber surface. After the high-temperature-triggered ceramic transformation, a thicker heat insulation barrier with more pores can be formed, thereby more effectively blocking the transfer of high-temperature heat. The amount of insulation slurry added for different temperature ranges can be obtained from the following experimental table. Table 1 Group number Dosage of thermal insulation mortar added (parts) Fabric thickness expansion rate at high temperature (500°C) (%) Thermal conductivity of the fabric at 500°C (W / (m·K)) Coating adhesion strength (grade) Comprehensive performance evaluation 1 5 3.2 0.105 excellent Insufficient expansion limits the improvement in thermal insulation performance. 2 8 8.5 0.092 excellent Effective expansion begins, significantly improving thermal insulation performance. 3 10 12.1 0.085 good Achieving a better balance between expansion and thermal insulation performance 4 12 13.5 0.083 good Performance is similar to 3, but cost is slightly higher. 5 15 14.0 0.082 qualified Performance improvement is not significant, adhesion strength decreases, and costs increase. Table 1 shows the experimental results for the addition amount of thermal insulation slurry in the low-temperature range of 300-500°C. Table 1 indicates that in this low-temperature range, when the addition amount is 8-12 parts, the fabric can achieve effective thermal expansion, the thermal conductivity is significantly reduced, and the coating adhesion remains good. When the addition amount is less than 8 parts, the functionality is insufficient; when it is more than 12 parts, performance improvement plateaus, becoming uneconomical, and excessive coating thickness may negatively impact mechanical properties. Therefore, 8-12 parts represents the optimal range for balancing performance and cost. Table 2 Group number Dosage of thermal insulation mortar added (parts) Fabric thickness expansion rate (%) at high temperature (700°C) Thermal conductivity of the fabric at 700°C (W / (m·K)) Fabric strength retention rate (%) after high temperature treatment Comprehensive performance evaluation 1 10 15.5 0.118 88 Expansion and insulation performance are acceptable, but there is room for improvement. 2 12 22.3 0.099 85 Significant expansion and excellent thermal insulation performance 3 13.5 25.8 0.094 82 High expansion coefficient, excellent thermal insulation performance, and best overall performance. 4 15 26.5 0.093 80 Performance is comparable to 3, but strength retention is slightly lower. 5 18 17.0 0.092 75 The performance improvement is slight, but the strength loss is significant, and the cost is too high. Table 2 shows the experimental results of adding thermal insulation slurry in the low-temperature range of 500-700°C. In the medium-temperature range, a higher degree of ceramic conversion is required to resist higher temperatures. When the addition amount is 12-15 parts, the fabric exhibits excellent expansion rate and low thermal conductivity at 700°C, while the matrix strength retention rate is within an acceptable range. 12 parts is insufficient for performance, and more than 15 parts will exacerbate the strength loss and reduce the cost-effectiveness. Therefore, 12-15 parts is the range for balancing performance and reliability at this temperature. Table 3 Group number Dosage of thermal insulation mortar added (parts) Fabric thickness expansion rate (%) at high temperature (900°C) Thermal conductivity of the fabric at 900°C (W / (m·K)) High-temperature anti-chalking properties of coating Comprehensive performance evaluation 1 13 18.0 0.145 Poor The coating is insufficient to withstand high temperatures and is prone to powdering and peeling. 2 15 28.5 0.120 qualified An effective heat insulation barrier begins to form. 3 17.5 35.0 0.103 good Forming a dense insulation layer, achieving optimal overall performance. 4 20 36.8 0.101 excellent It has excellent thermal insulation performance, but faces significant challenges in terms of processability and cost. 5 23 37.5 0.100 excellent The marginal effect of performance improvement is extremely low, and the consumption of slurry is high, making it uneconomical. Table 3 shows the experimental results for the addition amount of thermal insulation slurry in the low-temperature range of 700-900°C. In the high-temperature range, a sufficient amount of precursor is required to form a sufficiently thick and stable porous ceramic layer to cope with extreme thermal environments. When the addition amount is 15-20 parts, the fabric can still maintain a high volume expansion rate and effective thermal insulation capacity at 900°C, while the coating itself has good high-temperature stability; less than 15 parts may result in an incomplete coating; more than 20 parts contribute little to the final performance and are not economical; therefore, 15-20 parts is the necessary and economical dosage range to ensure effective operation at extreme temperatures.

[0022] S33. Transfer 80% of the sizing agent to a mixing tank with constant temperature and stirring function, turn on the stirring at 200–400 rpm, and set the water temperature of the mixing tank jacket at 40–50°C to improve the fluidity of the sizing agent under gentle heating. S34. After all the thermal insulation slurry is added, increase the stirring speed to 1200–1500 rpm and start the homogenizer. Under this condition, continue to stir with strong shear for 30–45 minutes to ensure that the thermal insulation slurry and the sizing agent are completely and uniformly miscible to form a uniform and stable composite system. S35. Slowly add the remaining 20% ​​of the sizing agent to the mixing tank, adjust the overall viscosity and solid content, and add defoamer at the same time. Adjust the stirring speed back to 300–500 rpm and continue stirring for 15–20 minutes to obtain the functional sizing agent. S36. Filter the functional sizing agent through a 200-300 mesh filter or filter bag to remove impurities generated during the mixing process. Transfer the filtered slurry to a clean storage tank and let it stand and mature at room temperature for 8 hours. S4. The drawn glass fiber monofilaments are evenly coated with a functional sizing agent by spraying. After curing, multiple monofilaments are bundled into a raw yarn and twisted by a twisting machine. Furthermore, the drawn glass fiber monofilaments are uniformly coated with a functional sizing agent by spraying. After curing, multiple monofilaments are bundled into a raw yarn and twisted using a twisting machine, including the following steps: S41. Guide the continuously running glass fiber monofilament after drawing into a sealed spraying chamber. Apply the prepared functional sizing agent evenly to the fiber surface in the form of atomization through a precision nozzle. By adjusting the spraying pressure, flow rate and fiber feeding speed, ensure that a complete, continuous and controllable coating layer is formed on the surface of each monofilament. S42. Place the coated glass fiber into a segmented temperature-controlled drying channel and keep it at 200–250°C for 1–2 minutes to allow the solvent in the coating to evaporate rapidly, while the organic components undergo preliminary cross-linking and curing, thereby forming a stable and functional film on the fiber surface. S43. The solidified monofilaments are precisely combined on the bundler, and neatly arranged and merged into a loosely structured, untwisted fiber bundle through the yarn guide eye. S44. The combined raw yarn is introduced into the twisting machine, and the yarn is twisted by the rotation of the spindle, so that the fibers are interlocked. The twisted yarn is then wound onto a standard yarn tube or bobbin with constant tension to form a regular yarn package.

[0023] S5. Using an air-jet loom, the twisted yarn is woven into a fabric as the base material for the insulation layer. The woven fabric is then heat-set and finally tested for thickness, density, thermal conductivity, and high-temperature expansion performance.

[0024] Furthermore, the woven fabric undergoes heat setting treatment, and finally, its thickness, density, thermal conductivity, and high-temperature expansion performance are tested, including the following steps: S51. Place the twisted yarn bobbin on the warping frame and use the warping machine to evenly wind the yarn onto the warp beam according to the designed arrangement, width and tension. S52. Install the prepared warp beams and weft yarn bobbins onto the air-jet loom. Based on the designed fabric structure and specifications, set the loom's process parameters such as weft insertion air pressure, shedding time, and weft striking force. S53. The air jet loom uses high-speed airflow ejected from the main nozzle and the relay nozzle to introduce the weft yarn into the shed formed by the warp yarn opening, and pushes the weft yarn towards the weft opening through the beating motion of the reed, so that the warp and weft yarns interweave according to the preset structure to form a fabric. S54. The woven continuous fabric is wound onto the unwinding roll to form a greige roll. The greige is then subjected to a preliminary inspection to check for defects such as broken warp, broken weft, or uneven density. S55. Place the blank in a heat setting machine to eliminate internal stress, stabilize the fabric size, and initially cure the functional coating. S56. For the treated fabric, use a fabric thickness gauge and balance to measure its thickness and mass per unit area at multiple points, and calculate its bulk density to ensure that its basic physical properties meet the design specifications; use a flat thermal conductivity meter or similar heat flow meter to measure the thermal conductivity of the fabric at a set standard temperature to evaluate its basic thermal insulation performance; place the fabric sample in a programmable temperature-controlled high-temperature box furnace to simulate its target working temperature range for heating, and quantify its volume expansion rate at high temperature by recording its size changes with temperature and time to verify the effectiveness and stability of its intermediate coating function; S57. Summarize all test data, evaluate the overall performance of the fabric, roll or fold qualified products into specified lengths, and pack them in moisture-proof packaging, affixing labels containing batch number, specifications and test results.

[0025] A high-temperature resistant fabric for steam turbine insulation layers, comprising the following raw materials: (The fabric is prepared using any of the above-mentioned high-temperature resistant fabrics and their manufacturing processes.) The raw materials for glass fiber monofilaments include high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides, among which the alkali metal oxides are Na2O+K2O. The raw materials for thermal insulation mortar include polysilazane prepolymer, nano alumina powder, xylene, silane coupling agent, and dispersant, wherein the dispersant is polyvinylpyrrolidone; The raw materials for the sizing agent include film-forming agents, lubricants, coupling agents, toughening agents, antistatic agents, and wetting agents; among which the film-forming agent is epoxy resin, the lubricant is polyethylene wax emulsion, the coupling agent is KH-550, the toughening agent is acrylate copolymer, the antistatic agent is polyether compound, and the wetting agent is polyether modified siloxane. Furthermore, the mass fractions of each raw material are as follows: The raw materials for glass fiber monofilaments include high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides, with 52-56 parts of high-purity quartz sand, 12-16 parts of alumina, 16-25 parts of calcium oxide, 8-13 parts of boric acid, 0-5 parts of magnesium oxide, and 0-2 parts of alkali metal oxides. The raw materials for thermal insulation mortar include polysilazane prepolymer, nano alumina powder, xylene, silane coupling agent, and dispersant, with 40–50 parts of polysilazane prepolymer, 20–30 parts of nano alumina powder, 25–35 parts of xylene, 1–2 parts of silane coupling agent, and 0.5–1 part of dispersant. The raw materials for the sizing agent include film-forming agents, lubricants, coupling agents, toughening agents, antistatic agents, and wetting agents; and the film-forming agent is 40-80 parts, the lubricant is 5-20 parts, the coupling agent is 2-15 parts, the toughening agent is 1-21 parts, the antistatic agent is 7-12 parts, and the wetting agent is 1-6 parts.

[0026] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for preparing a high-temperature resistant fabric for a steam turbine insulation layer, characterized in that, The process includes the following steps: S1. Weigh and mix high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides according to the formula, put them into a high-temperature melting furnace, melt them into a uniform glass liquid at 1500–1600°C, and then introduce the glass liquid into a platinum-rhodium alloy stencil to draw out continuous glass fiber monofilaments with a diameter of 3–9 micrometers. S2. Prepare thermal insulation slurry by mixing polysilazane prepolymer, nano-alumina powder, xylene, silane coupling agent, and dispersant; S3. Prepare the sizing agent, and determine the amount of thermal insulation slurry to be added according to the working temperature range of the steam turbine. Then mix the thermal insulation slurry and the sizing agent to form a uniform functional sizing agent. S4. The drawn glass fiber monofilaments are evenly coated with a functional sizing agent by spraying. After curing, multiple monofilaments are bundled into a raw yarn and twisted by a twisting machine. S5. Using an air-jet loom, the twisted yarn is woven into a fabric as the base material for the insulation layer. The woven fabric is then heat-set and finally tested for thickness, density, thermal conductivity, and high-temperature expansion performance.

2. The process for preparing a high-temperature resistant steam turbine insulation layer high-temperature fabric according to claim 1, characterized in that, The process of weighing and mixing high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides according to a formula, adding them to a high-temperature melting furnace, melting them into a uniform glass melt at 1500–1600°C, and then guiding the glass melt into a platinum-rhodium alloy stencil to draw out continuous glass fiber monofilaments with a diameter of 3–9 micrometers includes the following steps: S11. Weigh the high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides according to the formula, and then put them into a high-efficiency mixer to stir them thoroughly to ensure that each component is evenly distributed and form a batch material. S12. The uniformly mixed batch is continuously fed into a high-temperature melting furnace through a feeder and melted at a temperature of 1500–1600°C to completely transform it into a homogeneous glass melt. During this process, high-temperature clarification is completed to remove air bubbles from the melt. S13. The homogenized and clarified molten glass is led out through a flow hole or channel and enters a feeding channel with a precision temperature control system to adjust and stabilize the temperature of the molten glass at 1250°C. S14. The molten glass is introduced into a stencil made of platinum-rhodium alloy. A high-speed rotating wire drawing machine drum is used to draw the thin stream of molten glass flowing out of the stencil downwards at high speed. During the drawing process, forced air cooling is used to rapidly solidify it, forming continuous glass fiber monofilaments in the range of 3–9 micrometers in diameter.

3. The process for preparing a high-temperature resistant steam turbine insulation layer high-temperature fabric according to claim 1, characterized in that, The preparation of the thermal insulation slurry by using polysilazane prepolymer, nano-alumina powder, xylene, silane coupling agent, and dispersant includes the following steps: S21. Check and prepare the required raw materials to ensure the purity and dryness of the polysilazane prepolymer, nano alumina powder, xylene, silane coupling agent and dispersant. At the same time, introduce nitrogen into the reaction vessel to replace the internal air and establish an inert protective environment. S22. Under continuous nitrogen protection, add the polysilazane prepolymer and xylene solvent to a reactor equipped with a stirrer and temperature control device, control the temperature at 25-30°C, and stir at 300-500 rpm for 20-30 minutes to fully mix the two and form a uniform and transparent matrix solution. S23. Add nano-alumina powder, silane coupling agent and dispersant to the matrix solution in sequence, increase the stirring speed to 1500-2000 rpm, and continue to stir with strong shear for 30-40 minutes at this speed to initially wet and disperse the nano-powder in the solution to form a suspension slurry. S24. Transfer the initially dispersed slurry to the grinding jar of a planetary ball mill or sand mill, add zirconia grinding balls, and set the milling speed to 300-400 rpm for 6-8 hours. S25. Filter the ball-milled slurry through a 400-600 mesh precision sieve to remove trace large particles or impurities from the grinding process. Then transfer the filtered slurry to a vacuum degassing tank and let it stand or stir slowly under low vacuum for 10-20 minutes to remove air bubbles entrained in the slurry. S26. Fill the defoamed, uniform, and stable thermal insulation slurry into a sealed, opaque container, fill it with a small amount of nitrogen, seal it, affix a label indicating the ingredients, batch number, and preparation date, and store it in a cool, dry environment.

4. The process for preparing a high-temperature resistant steam turbine insulation layer high-temperature fabric according to claim 1, characterized in that, The preparation of the sizing agent, and the determination of the amount of thermal insulation slurry to be added based on the operating temperature range of the steam turbine, followed by mixing the thermal insulation slurry and the sizing agent to form a uniform functional sizing agent, includes the following steps: S31. Prepare film-forming agent, lubricant, coupling agent, toughening agent, antistatic agent, and wetting agent. Then, hydrolyze the coupling agent in deionized water at room temperature for 30-60 minutes. Subsequently, add the film-forming agent, lubricant, toughening agent, antistatic agent, and wetting agent in sequence with stirring. Heat the mixture to 50-80°C and stir continuously for 20-60 minutes to ensure that each component is fully emulsified and dispersed. Finally, adjust the pH value and filter to remove impurities to obtain a uniform and stable sizing agent emulsion. S32. Determine the amount of thermal insulation grout to be added based on the operating temperature range of the steam turbine; S33. Transfer 80% of the sizing agent to a mixing kettle equipped with a constant temperature and stirring function, turn on the stirring at 200–400 rpm, and set the water temperature of the mixing kettle jacket at 40–50°C to improve the fluidity of the sizing agent under gentle heating. S34. After all the thermal insulation slurry is added, increase the stirring speed to 1200–1500 rpm and start the homogenizer. Under this condition, continue to stir with strong shear for 30–45 minutes to ensure that the thermal insulation slurry and the sizing agent are completely and uniformly miscible to form a uniform and stable composite system. S35. Slowly add the remaining 20% ​​of the sizing agent to the mixing tank, adjust the overall viscosity and solid content, and add defoamer at the same time. Adjust the stirring speed back to 300–500 rpm and continue stirring for 15–20 minutes to obtain the functional sizing agent. S36. Filter the functional sizing agent through a 200-300 mesh filter or filter bag to remove impurities generated during the mixing process. Transfer the filtered slurry to a clean storage tank and let it stand and mature at room temperature for 8 hours.

5. The process for preparing a high-temperature resistant steam turbine insulation layer high-temperature fabric according to claim 1, characterized in that, Determining the amount of thermal insulation slurry to be added based on the operating temperature range of the steam turbine includes the following steps: S321. Divide the operating temperature range of the steam turbine into three zones: 300–500°C for low temperature, 500–700°C for medium temperature, and 700–900°C for high temperature; and add 8–12 parts of insulation slurry for the low temperature zone; 12–15 parts for the medium temperature zone; and 15–20 parts for the high temperature zone.

6. The process for preparing a high-temperature resistant steam turbine insulation layer high-temperature fabric according to claim 1, characterized in that, The process of uniformly coating the drawn glass fiber monofilaments with a functional sizing agent by spraying, curing the agent, bundling multiple monofilaments into a raw yarn, and then twisting it using a twisting machine includes the following steps: S41. Guide the continuously running glass fiber monofilament after drawing into a sealed spraying chamber. Apply the prepared functional sizing agent evenly to the fiber surface in the form of atomization through a precision nozzle. By adjusting the spraying pressure, flow rate and fiber feeding speed, ensure that a complete, continuous and controllable coating layer is formed on the surface of each monofilament. S42. Place the coated glass fiber into a segmented temperature-controlled drying channel and keep it at 200–250°C for 1–2 minutes to allow the solvent in the coating to evaporate rapidly, while the organic components undergo preliminary cross-linking and curing, thereby forming a stable and functional film on the fiber surface. S43. The solidified monofilaments are precisely combined on the bundler, and neatly arranged and merged into a loosely structured, untwisted fiber bundle through the yarn guide eye. S44. The combined raw yarn is introduced into the twisting machine, and the yarn is twisted by the rotation of the spindle, so that the fibers are interlocked. The twisted yarn is then wound onto a standard yarn tube or bobbin with constant tension to form a regular yarn package.

7. The process for preparing a high-temperature resistant steam turbine insulation layer high-temperature fabric according to claim 1, characterized in that, The process of using an air-jet loom to weave the twisted yarn into a fabric, which serves as the base material for the insulation layer, and then performing heat setting on the woven fabric, followed by testing of its thickness, density, thermal conductivity, and high-temperature expansion properties, includes the following steps: S51. Place the twisted yarn bobbin on the warping frame and use the warping machine to evenly wind the yarn onto the warp beam according to the designed arrangement, width and tension. S52. Install the prepared warp beams and weft yarn bobbins onto the air-jet loom. Based on the designed fabric structure and specifications, set the loom's process parameters such as weft insertion air pressure, shedding time, and weft striking force. S53. The air jet loom uses high-speed airflow ejected from the main nozzle and the relay nozzle to introduce the weft yarn into the shed formed by the warp yarn opening, and pushes the weft yarn towards the weft opening through the beating motion of the reed, so that the warp and weft yarns interweave according to the preset structure to form a fabric. S54. The woven continuous fabric is wound onto the unwinding roll to form a greige roll. The greige is then subjected to a preliminary inspection to check for defects such as broken warp, broken weft, or uneven density. S55. Place the blank in a heat setting machine to eliminate internal stress, stabilize the fabric size, and initially cure the functional coating. S56. For the treated fabric, use a fabric thickness gauge and a balance to measure its thickness and mass per unit area at multiple points, and calculate its bulk density to ensure that its basic physical properties meet the design specifications. The thermal conductivity of the fabric was measured at a set standard temperature using a flat plate thermal conductivity meter or similar heat flow meter to evaluate its basic thermal insulation performance. The fabric sample was placed in a high-temperature box furnace with programmable temperature control to simulate its target operating temperature range. By recording the changes in its size with temperature and time, its volume expansion rate at high temperature was quantified to verify the effectiveness and stability of its intermediate coating function. S57. Summarize all test data, evaluate the overall performance of the fabric, roll or fold qualified products into specified lengths, and pack them in moisture-proof packaging, affixing labels containing batch number, specifications and test results.

8. A high-temperature resistant fabric for the insulation layer of a steam turbine, characterized in that, The fabric is prepared using the high-temperature resistant steam turbine insulation layer fabric preparation process described in any one of claims 1-7, and its raw materials include: The raw materials for glass fiber monofilaments include high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides, among which the alkali metal oxides are Na2O+K2O. The raw materials for thermal insulation mortar include polysilazane prepolymer, nano alumina powder, xylene, silane coupling agent, and dispersant, wherein the dispersant is polyvinylpyrrolidone; The raw materials for the sizing agent include film-forming agent, lubricant, coupling agent, toughening agent, antistatic agent, and wetting agent; among which the film-forming agent is epoxy resin, the lubricant is polyethylene wax emulsion, the coupling agent is KH-550, the toughening agent is acrylate copolymer, the antistatic agent is polyether compound, and the wetting agent is polyether modified siloxane.

9. The high-temperature resistant fabric for a steam turbine insulation layer according to claim 8, characterized in that, The mass fractions of each raw material are as follows: The raw materials for glass fiber monofilaments include high-purity quartz sand, alumina, calcium oxide, boric acid, magnesium oxide, and alkali metal oxides, with 52-56 parts of high-purity quartz sand, 12-16 parts of alumina, 16-25 parts of calcium oxide, 8-13 parts of boric acid, 0-5 parts of magnesium oxide, and 0-2 parts of alkali metal oxides. The raw materials for thermal insulation mortar include polysilazane prepolymer, nano alumina powder, xylene, silane coupling agent, and dispersant, with 40–50 parts of polysilazane prepolymer, 20–30 parts of nano alumina powder, 25–35 parts of xylene, 1–2 parts of silane coupling agent, and 0.5–1 part of dispersant. The raw materials for the sizing agent include film-forming agents, lubricants, coupling agents, toughening agents, antistatic agents, and wetting agents; and the film-forming agent is 40-80 parts, the lubricant is 5-20 parts, the coupling agent is 2-15 parts, the toughening agent is 1-21 parts, the antistatic agent is 7-12 parts, and the wetting agent is 1-6 parts.

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