A passive dehumidification medium and method for electrical distribution equipment
Patent Information
- Application Number
- CN202611208771.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-11
- Publication Date
- 2026-09-08
AI Technical Summary
[0004]本发明的目的在于：提供了一种用于配电设备的无源除湿介质及除湿方法，解决了目前3A分子筛虽然对水分子具有高选择性，但其吸湿容量低
[0021] 1. The present invention provides a passive dehumidifying medium for power distribution equipment with a core-shell structure. The outer shell is mainly composed of hydrophobically modified 3A molecular sieve, which provides channels for water molecules to pass through and intercepts large molecules, thereby improving the selectivity of the passive dehumidifying medium for water molecules. After hydrophobic modification, the 3A molecular sieve in this structure only acts as a screening and filtering layer for water molecules and does not significantly adsorb water, thus avoiding the 3A molecular sieve preferentially adsorbing a large amount of water molecules before the core material and hindering water from passing through the outer layer into the core.
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Figure CN122702284A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of power distribution equipment dehumidification technology, and relates to a passive dehumidification medium and dehumidification method for power distribution equipment. Background Technology
[0002] Common power distribution equipment, such as JP integrated distribution boxes, integrated primary and secondary ring main units, and prefabricated substations, are mostly installed outdoors or semi-outdoor in environments, enduring harsh weather conditions such as day-night temperature differences, high humidity, and salt spray year-round. When the ambient temperature drops suddenly or the humidity inside the cabinet reaches the dew point, condensation will occur on the surface of the metal components inside the cabinet, leading to a shortened creepage distance and a decrease in insulation strength. In severe cases, this can cause serious faults such as phase-to-phase short circuits and flashover breakdowns.
[0003] Currently, commonly used dehumidification methods in the industry mainly fall into two categories: active and passive. Active dehumidification, such as heaters and mini dehumidifiers, while effective, suffers from high energy consumption, requires external power, and is prone to accelerated component aging and failure due to localized overheating, making it unsuitable for scenarios requiring passive dehumidification. Passive dehumidification primarily relies on desiccants, such as silica gel, calcium chloride, and ordinary molecular sieves. Ordinary molecular sieves, such as 3A molecular sieves, have high selectivity for water molecules but low adsorption capacity; silica gel and calcium chloride have relatively high adsorption capacity, but their selectivity for water molecules is relatively lower than that of 3A molecular sieves. Summary of the Invention
[0004] The purpose of this invention is to provide a passive dehumidification medium and dehumidification method for power distribution equipment, which solves the problem that although 3A molecular sieves have high selectivity for water molecules, their moisture absorption capacity is low.
[0005] The technical solution adopted in this invention is as follows:
[0006] A passive dehumidifying medium for power distribution equipment includes a core-shell structure; the outer shell of the core-shell structure is a hydrophobically modified porous structure, and the core material is a water-absorbing porous structure.
[0007] The raw materials for preparing the shell include the following components in parts by weight: 75-80 parts of 3A molecular sieve raw powder, 20-25 parts of silicon-aluminum composite sol-modified clay composite, and surface hydrophobic modifier.
[0008] The raw materials for preparing the core material include the following components in parts by weight: 100 parts magnesium hydroxide, 40-50 parts boehmite, 1-2 parts lithium hydroxide, 6-10 parts MgAl-LDO and 10-12 parts hydrophobically modified diatomaceous earth.
[0009] Furthermore, the silicon-aluminum composite sol-modified clay composite comprises the following components in parts by weight: 100 parts silicon-aluminum composite sol, 55-60 parts metakaolin, and 1-3 parts nano zinc oxide whiskers.
[0010] Furthermore, the silicon-aluminum composite sol is a mixture of silica sol and aluminum sol, wherein the weight ratio of silica sol (calculated as SiO2) to aluminum sol (calculated as Al2O3) in the silicon-aluminum sol is 2.5:1; the metakaolin is metakaolin obtained by calcining kaolin at 850℃ and holding it at that temperature for 2 hours.
[0011] Furthermore, the silicon-aluminum composite sol-modified clay composite is prepared by the following method: alkaline silica sol with pH 9-10 is slowly added to acidic aluminum sol with pH 2-3 under stirring, and stirred evenly to obtain silicon-aluminum composite sol; metakaolin is added to silicon-aluminum composite sol, and after stirring for 3 hours, nano zinc oxide whiskers are added, homogenized and dispersed, and spray dried to obtain silicon-aluminum composite sol-modified clay composite.
[0012] Furthermore, the hydrophobically modified diatomaceous earth is prepared by the following method:
[0013] A. Disperse diatomaceous earth in water to form a suspension; dissolve calcium nitrate tetrahydrate in deionized water to obtain a calcium salt solution; dissolve diammonium hydrogen phosphate in deionized water, adjust the pH to 11 with ammonia water to obtain a phosphate solution; slowly add the phosphate solution dropwise to the diatomaceous earth suspension while stirring, then add the calcium salt solution dropwise, controlling the Ca / P molar ratio to 1.67, and stir until homogeneous to obtain a mixed solution; transfer the mixed solution to a hydrothermal reactor, add citric acid, and hydrothermally react at 180℃ for 18 hours. After the reaction is complete, cool, filter, wash until neutral, and dry to obtain a modified diatomaceous earth intermediate;
[0014] B. The modified diatomaceous earth intermediate was immersed in a 10wt% glucose aqueous solution and stirred for 2 hours. After filtration, the wet material was transferred to a hydrothermal reactor and hydrothermally reacted at 200℃ for 6 hours. After the reaction was completed, it was cooled and removed, then transferred to a tube furnace and heated to 850℃ at 5℃ / min under a nitrogen atmosphere. After holding at this temperature for 1.5 hours, it was cooled to room temperature to obtain hydrophobic modified diatomaceous earth.
[0015] Furthermore, the MgAl-LDO is prepared by calcining magnesium aluminum hydrotalcite with a Mg / Al molar ratio of 3:1 at 500°C for 4 hours to obtain MgAl-LDO.
[0016] Furthermore, the surface hydrophobic modifier is a silane coupling agent KH-550.
[0017] Furthermore, the passive dehumidification medium is prepared by the following method:
[0018] S1. Mix magnesium hydroxide, boehmite, lithium hydroxide, MgAl-LDO, and hydrophobically modified diatomaceous earth evenly, add deionized water and stir to form a plastic slurry, extrude and sphericalize the granules, and pre-dry to obtain spherical precursor particles with a particle size of 1.5~2.0 mm; S2. Mix 3A molecular sieve raw powder and silicon-aluminum composite sol-modified clay composite evenly, add deionized water to form a slurry; S3. Coat the surface of the spherical precursor particles obtained in step S1 with the slurry obtained in step S2 to form a shell layer, the wet material thickness of the shell layer reaches 200 μm, and dry to obtain a core-shell structured preform; S4. Place the core-shell structured preform under an inert atmosphere, heat to 580~600℃, and calcine for 2~4 hours; then immerse the calcined particles in an alcohol-water solution of silane coupling agent, remove and dry at 100~110℃ to obtain a passive dehumidifying medium.
[0019] A dehumidification method includes the following steps: filling the passive dehumidification medium into a breathable flame-retardant container to form a dehumidification module, fixing it inside the power distribution equipment box, and maintaining an electrical clearance of ≥20mm from live parts; the power distribution equipment includes a JP integrated distribution box, a primary and secondary integrated ring network box, and a box-type substation.
[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:
[0021] 1. The present invention provides a passive dehumidifying medium for power distribution equipment with a core-shell structure. The outer shell is mainly composed of hydrophobically modified 3A molecular sieve, which provides channels for water molecules to pass through and intercepts large molecules, thereby improving the selectivity of the passive dehumidifying medium for water molecules. After hydrophobic modification, the 3A molecular sieve in this structure only acts as a screening and filtering layer for water molecules and does not significantly adsorb water, thus avoiding the 3A molecular sieve preferentially adsorbing a large amount of water molecules before the core material and hindering water from passing through the outer layer into the core.
[0022] 2. In this invention, after the core-shell structure preform is calcined at 580~600℃, the core material is mainly composed of calcined products of magnesium hydroxide and boehmite, forming a lithium-doped composite oxide water-absorbing structure. Combined with MgAl-LDO and hydrophobically modified diatomite, the core has a stable moisture diffusion channel and a highly efficient dehumidification effect. In addition, the combined effect of MgAl-LDO and hydrophobically modified diatomite enables the core to maintain particle integrity after multiple regeneration cycles. Attached Figure Description
[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein:
[0024] Figure 1 This is a physical image of the passive dehumidifying medium prepared in Example 1 of the present invention;
[0025] Figure 2 This is a picture of the 3A molecular sieve raw powder used in this invention. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0027] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0028] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0029] The features and performance of the present invention will be further described in detail below with reference to embodiments.
[0030] Example 1
[0031] A passive dehumidifying medium for power distribution equipment, provided in a preferred embodiment of the present invention, is prepared by the following method:
[0032] Preparation of hydrophobically modified diatomaceous earth:
[0033] A. Weigh 100g of raw diatomaceous earth (particle size 20-50μm), immerse it in 500mL of deionized water, and ultrasonically disperse it for 30 minutes to obtain a diatomaceous earth suspension; dissolve 23.6g of calcium nitrate tetrahydrate in 300mL of deionized water to prepare a calcium salt solution; dissolve 7.9g of diammonium hydrogen phosphate in 200mL of deionized water, adjust the pH to 11 with ammonia water to obtain a phosphate solution; slowly add the phosphate solution dropwise to the diatomaceous earth suspension while stirring, then add the calcium salt solution dropwise, with a Ca / P molar ratio of 1.67, to obtain a mixed solution; transfer the mixed solution to a 1L hydrothermal reactor, add 0.5g of citric acid, and hydrothermally react at 180℃ for 18 hours; after the reaction is complete, cool, filter, wash the solid with deionized water until neutral, and dry at 80℃ for 12 hours to obtain a modified diatomaceous earth intermediate;
[0034] B. Immerse 100g of modified diatomaceous earth intermediate in a 10wt% glucose aqueous solution, stir for 2 hours, filter, and transfer the wet material to a hydrothermal reactor. React hydrothermally at 200℃ for 6 hours. After the reaction is complete, cool and remove the material, transfer it to a tube furnace, and heat it to 850℃ at 5℃ / min under a nitrogen atmosphere. Hold the temperature for 1.5 hours and then cool it to room temperature to obtain hydrophobic modified diatomaceous earth with a water contact angle of 156°.
[0035] Preparation of MgAl-LDO:
[0036] Weigh 100g of magnesium aluminum hydrotalcite with a Mg / Al molar ratio of 3:1, place it in a muffle furnace, heat it to 500℃ at 3℃ / min, keep it at that temperature for 4 hours, cool and grind it, sieve it to obtain MgAl-LDO, and seal it for storage.
[0037] Preparation of silicon-aluminum composite sol-modified clay composite:
[0038] 100g of alkaline silica sol (pH 9.5, calculated as SiO2) was slowly added to 40g of acidic aluminum sol (pH 2.5, calculated as Al2O3) under stirring, and the mixture was stirred until homogeneous to obtain a silica-alumina composite sol. 100g of the silica-alumina composite sol was taken, and 58g of metakaolin was added to it. After stirring for 3 hours, 2g of nano-zinc oxide whiskers were added. The mixture was homogeneously dispersed for 30 minutes and then spray-dried to obtain a silica-alumina composite sol-modified clay composite. The metakaolin was obtained by calcining kaolin at 850℃ for 2 hours.
[0039] Preparation of passive dehumidification media:
[0040] S1: Weigh 100g of magnesium hydroxide powder, 45g of boehmite powder, 1.5g of lithium hydroxide, 8g of MgAl-LDO, and 11g of hydrophobically modified diatomaceous earth. Dry mix them in a mixer for 30 minutes, then slowly add 80mL of deionized water and stir to form a plastic slurry. Extrude and roll the granules to form a ball shape. Dry them in a fluidized bed at 60℃ until the moisture content is <2%. Sieve out spherical precursor particles with a particle size of 1.5-2.0mm.
[0041] S2: Weigh out the 3A molecular sieve raw powder (3A zeolite molecular sieve raw powder provided by Shanghai Gaowei Industrial Technology Co., Ltd., such as...) Figure 2 (As shown) 75g and 25g of silicon-aluminum composite sol-modified clay composite were mixed evenly, and 45mL of deionized water was added and stirred into a uniform slurry.
[0042] S3: Wrap the slurry obtained in step S2 around the surface of the spherical precursor particles obtained in step S1 to form an outer shell layer. The wet material thickness of the outer shell layer reaches 200μm. After drying, a core-shell structured preform is obtained.
[0043] S4: Place the core-shell structured preform in a tube furnace, heat it to 590℃ at a rate of 5℃ / min under a nitrogen atmosphere, and calcine it for 3 hours. After cooling, immerse it in an alcohol-water solution (containing ethanol and water in a volume ratio of 9:1) with a concentration of 2wt% KH-550 silane coupling agent for 30 minutes. Remove it, drain it, and dry it at 105℃ for 2 hours to obtain a passive dehumidifying medium (for direct use in detection). See the attached images for the actual product and internal cross-sectional views of a single particle. Figure 1 As shown.
[0044] Dehumidification module assembly:
[0045] The passive dehumidifying medium is filled into the flame-retardant polycarbonate breathable box (75 vol%), and the breathable surface is made of expanded polytetrafluoroethylene microporous membrane.
[0046] Example 2
[0047] This embodiment is based on Example 1, and the only difference from Example 1 is that the amount of boehmite in S1 is adjusted to 50g, the amount of MgAl-LDO is adjusted to 10g, and the amount of hydrophobic modified diatomite is adjusted to 12g; the rest is the same as Example 1.
[0048] Example 3
[0049] The example is based on Example 1, except that the amount of boehmite in S1 is adjusted to 40g, the amount of MgAl-LDO is adjusted to 6g, and the amount of hydrophobic modified diatomite is adjusted to 10g; the rest is the same as Example 1.
[0050] Comparative Example 1
[0051] This comparative example provides a 3A molecular sieve adsorbent, using 3A molecular sieve raw powder (3A zeolite molecular sieve raw powder provided by Shanghai Gaowei Industrial Technology Co., Ltd., such as...) Figure 2 75g of the powder (as shown) and 25g of the binder kaolin were mixed in a powder mixer. After stirring, the powder was added while spraying water using a pelletizing machine and its built-in powder adding and water spraying device. The powder was rolled and agglomerated from small balls into large balls to obtain wet balls. The wet balls were preheated at 450℃ for 20 minutes, and then heated to 600℃ at a heating rate of 10℃ / min and calcined for 2 hours. After calcination, the particles were cooled to obtain 3A molecular sieve adsorbent with an average particle size of 2mm.
[0052] Comparative Example 2
[0053] Based on Example 1, this comparative example provides a dehumidifying medium that differs from Example 1 in that steps S2 and S3 are omitted, and the spherical precursor particles obtained in S1 are directly calcined in S4. After calcination, no KH-550 silane coupling agent modification is performed, and the dehumidifying medium is obtained directly.
[0054] Comparative Example 3
[0055] Based on Example 1, this comparative example provides a dehumidification medium that differs from Example 1 in that hydrophobic modified diatomaceous earth is not added in this comparative example S1; otherwise, it is the same as Example 1.
[0056] Comparative Example 4
[0057] Based on Example 1, this comparative example provides a dehumidification medium that differs from Example 1 in that MgAl-LDO is not added in this comparative example S1; otherwise, it is the same as Example 1.
[0058] Comparative Example 5
[0059] Based on Example 1, this comparative example provides a dehumidifying medium that differs from Example 1 in that it does not undergo KH-550 silane coupling agent impregnation treatment in Comparative Example S4, and is directly used as the finished product after calcination; otherwise, it is consistent with Example 1.
[0060] Experimental Example 1
[0061] Static water adsorption rate detection
[0062] Referring to GB / T 6287-2021 Method for Static Water Adsorption of Molecular Sieves, the static water adsorption rate of the dehumidifying media (desiccant) prepared in Examples 1-3 and Comparative Examples 1-5 was tested at 10% humidity and 25℃. The average value of the three parallel samples was taken. The results are shown in Table 1.
[0063] Referring to the molecular sieve crushing resistance test method in HG / T 2783-1996, the crushing resistance of the dehumidifying media (desiccant) prepared in Examples 1-3 and Comparative Examples 1-5 was tested respectively. The average value of the three groups of parallel samples was taken, and the results are shown in Table 1.
[0064] The volume resistivity of the dehumidifying media (desiccant) prepared in Examples 1-3 and Comparative Examples 1-5 was tested according to the standard GB / T 31838.2-2019. The average value of the three parallel samples was taken, and the results are shown in Table 1.
[0065] Dust generation: 100g of sample was placed in a sealed container and vibrated on a vibration table at an amplitude of 1.5mm and a frequency of 50Hz for 30 minutes. The weight of the material passing through a 200-mesh sieve was measured. The average value of the three parallel samples was taken. The results are shown in Table 1.
[0066] Table 1. Test results of basic performance of dehumidifying media
[0067] Static water adsorption rate (wt%) Crushing force (N) Volume resistivity (Ω·cm) Dust generation (mg / 100g) Example 1 30.3 120.5 <![CDATA[2.8×10 13 ]]> 4.8 Example 2 29.8 120.6 <![CDATA[2.7×10 13 ]]> 4.2 Example 3 28.7 118.8 <![CDATA[2.1×10 13 ]]> 6.0 Comparative Example 1 21.2 81.5 <![CDATA[8.6×10 12 ]]> 10.4 Comparative Example 2 26.6 63.2 <![CDATA[2.2×10 12 ]]> 28.7 Comparative Example 3 24.5 116.8 <![CDATA[2.3×10 13 ]]> 6.8 Comparative Example 4 25.2 115.4 <![CDATA[2.0×10 13 ]]> 7.4 Comparative Example 5 23.8 119.3 <![CDATA[7.4×10 12 ]]> 5.5
[0068] Experimental Example 2
[0069] The cyclic regeneration performance of the dehumidifying media (desiccant) prepared in Example 1 and Comparative Examples 3 and 4 was tested, and the results are shown in Table 2.
[0070] Cyclic regeneration performance: The sample after moisture absorption saturation was heated at 400℃ for 3 hours; after cooling, it was immersed in an alcohol-water solution of 2wt% KH-550 silane coupling agent (the alcohol-water solution included ethanol and water in a volume ratio of 9:1) for 30 minutes, taken out and drained, and dried at 105℃ for 2 hours to obtain the regenerated passive desiccant. Moisture absorption saturation → hydrophobic regeneration treatment constitutes one cycle. The static water adsorption rate and sphericity of the desiccant (drying agent) were measured at the initial stage and after 10 cycles. The weight loss rate of the desiccant (drying agent) after 10 cycles was also measured. The weight loss rate = (m0- m1) / m0×100%, where m0 is the initial weight of the desiccant (drying agent) and m1 is the weight of the desiccant (drying agent) after 10 cycles. The average value of the three parallel samples was taken.
[0071] Table 2 Results of Cyclic Regeneration Performance Test
[0072] Initial static water adsorption rate (wt%) Static water adsorption rate (wt%) after 10 cycles Initial sphericity Sphericity after 10 cycles Weight loss rate (wt%) after 10 cycles Example 1 30.3 28.7 0.98 0.95 0.8 Comparative Example 3 24.5 17.2 0.98 0.79 3.2 Comparative Example 4 25.2 18.5 0.98 0.82 4.5
[0073] Experimental Example 3
[0074] The dehumidification efficiency of the dehumidifying media (desiccant) prepared in Example 1 and Comparative Example 1 in a carbon dioxide gas environment was tested as follows: 1.0 g of the sample to be tested was vacuum dried to constant weight at 105℃ and then quickly transferred to the test chamber and sealed. The test chamber was a sealed test chamber with inert inner walls and a volume of 50 L, and the temperature could be precisely controlled to 25℃. The prepared mixed gas was injected into the test chamber through the gas injection port, so that the initial state of the gas in the chamber was: temperature 25℃, relative humidity 80%RH, 14 vol% carbon dioxide, 21 vol% oxygen, and the balance being nitrogen. The chamber was left to stand for 24 hours under sealed conditions at 25℃, and the relative humidity of the gas in the chamber was measured after 24 hours. The humidity change rate was calculated as follows: Humidity change rate (%) = (initial humidity - ... (24-hour humidity) / initial humidity × 100%; Remove the sample and place it in a tube furnace. Before heating, purge the furnace tube with high-purity nitrogen for 10-15 minutes. Regenerate for 3 hours at 400℃ under nitrogen purging. Collect the released gas and analyze the CO2 content in the released gas using gas chromatography. If it is lower than the detection limit, it is considered that carbon dioxide has not been detected. Take the average value of three parallel samples. The results are shown in Table 3.
[0075] Table 3 Dehumidification efficiency test results
[0076] Humidity change rate (%) after 24 hours of static adsorption <![CDATA[CO₂ content in desorbed gas]]> Example 1 28.5% Below the detection limit Comparative Example 1 17.5% Below the detection limit
[0077] As shown in Tables 1-3, the dehumidifying medium prepared in this application has regenerated structural stability, increases the moisture absorption rate compared with the prior art (reference document 1), has a crushing force greater than 110N, and has insulation properties, making it suitable for use in power distribution equipment.
[0078] Application examples
[0079] The passive dehumidifying medium prepared in Example 1 was filled into a flame-retardant polycarbonate breathable box with a filling amount of 75 vol%. The breathable surface was sealed with an expanded polytetrafluoroethylene microporous membrane to form a standard dehumidifying module, which was fixedly installed inside the power distribution equipment box, maintaining an electrical clearance of ≥20 mm from live parts. The power distribution equipment includes a JP integrated distribution box, a primary and secondary integrated ring network box, and a box-type substation. During the non-rainy season, the passive dehumidifying medium is in service and can help maintain the relative humidity of the internal environment of the power distribution equipment below 60%.
[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A passive dehumidifying medium for power distribution equipment, characterized in that: It includes a core-shell structure; the outer shell of the core-shell structure is a hydrophobically modified porous structure, and the core material is a water-absorbing porous structure; The raw materials for preparing the shell include the following components in parts by weight: 75-80 parts of 3A molecular sieve raw powder, 20-25 parts of silicon-aluminum composite sol-modified clay composite, and surface hydrophobic modifier. The raw materials for preparing the core material include the following components in parts by weight: 100 parts magnesium hydroxide, 40-50 parts boehmite, 1-2 parts lithium hydroxide, 6-10 parts MgAl-LDO and 10-12 parts hydrophobically modified diatomaceous earth.
2. The passive dehumidifying medium for power distribution equipment according to claim 1, characterized in that: The silicon-aluminum composite sol-modified clay composite comprises the following components in parts by weight: 100 parts silicon-aluminum composite sol, 55-60 parts metakaolin, and 1-3 parts nano zinc oxide whiskers.
3. The passive dehumidifying medium for power distribution equipment according to claim 2, characterized in that: The silicon-aluminum composite sol is a mixture of silica sol and aluminum sol, wherein the weight ratio of silica sol (calculated as SiO2) to aluminum sol (calculated as Al2O3) in the silicon-aluminum sol is 2.5:1; the metakaolin is metakaolin obtained by calcining kaolin at 850℃ and holding for 2 hours.
4. The passive dehumidifying medium for power distribution equipment according to claim 3, characterized in that: The silicon-aluminum composite sol-modified clay composite was prepared by the following method: alkaline silica sol with pH 9-10 was slowly added to acidic aluminum sol with pH 2-3 under stirring, and stirred evenly to obtain silicon-aluminum composite sol; metakaolin was added to the silicon-aluminum composite sol, and after stirring for 3 hours, nano zinc oxide whiskers were added, homogenized and dispersed, and spray dried to obtain silicon-aluminum composite sol-modified clay composite.
5. The passive dehumidifying medium for power distribution equipment according to claim 1, characterized in that: The hydrophobically modified diatomaceous earth was prepared by the following method: A. Disperse diatomaceous earth in water to form a suspension; dissolve calcium nitrate tetrahydrate in deionized water to obtain a calcium salt solution; dissolve diammonium hydrogen phosphate in deionized water, adjust the pH to 11 with ammonia water to obtain a phosphate solution; slowly add the phosphate solution dropwise to the diatomaceous earth suspension while stirring, then add the calcium salt solution dropwise, controlling the Ca / P molar ratio to 1.67, and stir until homogeneous to obtain a mixed solution; transfer the mixed solution to a hydrothermal reactor, add citric acid, and hydrothermally react at 180℃ for 18 hours. After the reaction is complete, cool, filter, wash until neutral, and dry to obtain a modified diatomaceous earth intermediate; B. The modified diatomaceous earth intermediate was immersed in a 10wt% glucose aqueous solution and stirred for 2 hours. After filtration, the wet material was transferred to a hydrothermal reactor and hydrothermally reacted at 200℃ for 6 hours. After the reaction was completed, it was cooled and removed, then transferred to a tube furnace and heated to 850℃ at 5℃ / min under a nitrogen atmosphere. After holding at this temperature for 1.5 hours, it was cooled to room temperature to obtain hydrophobic modified diatomaceous earth.
6. The passive dehumidifying medium for power distribution equipment according to claim 1, characterized in that: The MgAl-LDO was prepared by calcining magnesium aluminum hydrotalcite with a Mg / Al molar ratio of 3:1 at 500°C for 4 hours to obtain MgAl-LDO.
7. A passive dehumidifying medium for power distribution equipment according to claim 1, characterized in that: The surface hydrophobic modifier is a silane coupling agent KH-550.
8. The passive dehumidifying medium for power distribution equipment according to claim 1, characterized in that: The passive dehumidification medium is prepared by the following method: S1. Mix magnesium hydroxide, boehmite, lithium hydroxide, MgAl-LDO, and hydrophobically modified diatomaceous earth evenly, add deionized water and stir to form a plastic slurry, extrude and sphericalize the granules, and pre-dry to obtain spherical precursor particles with a particle size of 1.5~2.0 mm; S2. Mix 3A molecular sieve raw powder with silicon-aluminum composite sol-modified clay composite evenly, add deionized water to form a slurry; S3. Coat the surface of the spherical precursor particles obtained in step S1 with the slurry obtained in step S2 to form a shell layer, the wet material thickness of the shell layer reaches 200 μm, and dry to obtain a core-shell structured preform; S4. Place the core-shell structured preform under an inert atmosphere, heat to 580~600℃, and calcine for 2~4 hours; then immerse the calcined particles in an alcohol-water solution of silane coupling agent, remove and dry at 100~110℃ to obtain a passive dehumidifying medium.
9. A dehumidification method using a passive dehumidifying medium for power distribution equipment as described in any one of claims 1-8, characterized in that: Includes the following steps: The passive dehumidifying medium is filled into a breathable and flame-retardant container to form a dehumidifying module, which is fixedly installed inside the power distribution equipment box, maintaining an electrical clearance of ≥20mm from live parts; the power distribution equipment includes a JP integrated distribution box, a primary and secondary integrated ring network box, and a box-type substation.