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WO2014114220A1 - 一种纳米熔盐传热蓄热介质及其制备方法与应用 - Google Patents

一种纳米熔盐传热蓄热介质及其制备方法与应用 Download PDF

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Publication number
WO2014114220A1
WO2014114220A1 PCT/CN2014/070967 CN2014070967W WO2014114220A1 WO 2014114220 A1 WO2014114220 A1 WO 2014114220A1 CN 2014070967 W CN2014070967 W CN 2014070967W WO 2014114220 A1 WO2014114220 A1 WO 2014114220A1
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WIPO (PCT)
Prior art keywords
molten salt
heat
nitrate
storage medium
heat transfer
Prior art date
Application number
PCT/CN2014/070967
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English (en)
French (fr)
Inventor
曾智勇
Original Assignee
深圳市爱能森科技有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from CN201310029569.6A external-priority patent/CN103881662B/zh
Priority claimed from CN201310053597.1A external-priority patent/CN103881663B/zh
Priority claimed from CN201310732781.9A external-priority patent/CN103911121B/zh
Priority claimed from CN201310731910.2A external-priority patent/CN103923619B/zh
Application filed by 深圳市爱能森科技有限公司 filed Critical 深圳市爱能森科技有限公司
Priority to ES14742973T priority Critical patent/ES2884173T3/es
Priority to US14/762,938 priority patent/US10351748B2/en
Priority to EP14742973.2A priority patent/EP2949722B1/en
Publication of WO2014114220A1 publication Critical patent/WO2014114220A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
    • C09K5/08—Materials not undergoing a change of physical state when used
    • C09K5/10—Liquid materials
    • C09K5/12—Molten materials, i.e. materials solid at room temperature, e.g. metals or salts

Definitions

  • Nano-molten salt heat transfer and heat storage medium preparation method and application thereof
  • the invention relates to the technical field of heat storage and transfer, in particular to a nano molten salt heat transfer and heat storage medium and a preparation method and application thereof.
  • the heat storage heat transfer medium currently used mainly includes air, water, heat transfer oil, molten salt, sodium and aluminum. Due to its wide temperature range of use, low vapor pressure, low viscosity, good stability, low cost, etc., molten salt has become a potential heat transfer and heat storage medium in solar thermal power generation technology. More mature heat transfer and heat storage medium.
  • High-temperature molten salts mainly include nitrates, carbonates, sulfates, fluorides, chlorides, oxides, and the like.
  • the molten salt of nitric acid has great advantages.
  • the molten salt system of nitric acid has the disadvantages of less heat of dissolution and low thermal conductivity, and is easily decomposed at high temperatures.
  • researchers have tried to add other components to the nitrate molten salt system to solve the above problems, but the upper limit working temperature of the improved molten salt molten salt system is increased, and the lower limit working temperature is also increased, resulting in cloud cover maintenance. The cost increases.
  • Alkali metal carbonate has high melting point, good thermal stability and high upper limit temperature.
  • the lower limit use temperature is also increased accordingly, and the energy consumption also causes the maintenance cost to become higher.
  • the phase change latent heat of the fluorine salt molten salt is high, and the heat storage medium having different phase transition temperatures can be obtained by mixing the fluorine salts of different melting points, thereby meeting the requirements of the space solar thermal power generation cycle in a wide temperature range.
  • Fluorine salts can meet their thermal performance and compatibility requirements, but one of the obvious disadvantages is their low thermal conductivity and large volume shrinkage during solidification.
  • the present invention provides a nano-fused salt heat transfer and heat storage medium, a preparation method and application thereof, and the nano-fused salt heat transfer and heat storage medium of the invention has high thermal conductivity and can ensure The upper limit of the operating temperature of the whole system is high, and the lower working temperature is also guaranteed, which effectively reduces the maintenance cost, greatly expands the operating temperature range of the molten salt system, and can be widely used in the field of industrial energy storage and solar thermal power generation. .
  • Nano-molten salt heat transfer and heat storage medium characterized in: metal oxide nanoparticles and/or non-metal oxide nanoparticles
  • the rice particles are dispersed and mixed into a molten salt system.
  • the nanoparticles are SiO 2 , ZnO, Al 2 O 3 , TiO 2 , MgO and/O Ca nanoparticles, and the nanoparticles have an average particle diameter of 10 to 30 nm.
  • the molten salt system is a nitrate molten salt system.
  • the nitrate molten salt system is a binary nitrate molten salt system, wherein the weight of the nanoparticles accounts for 1%-5 in the heat transfer and heat storage medium; and the binary nitrate molten salt system is KN0 3 -NaN0 3 .
  • the composition of each component is: potassium nitrate 20-40 parts; sodium nitrate 60-80 parts binary nitrate molten salt system KN0 3 -NaN0 3 ;
  • the binary nitrate molten salt system is KN0 3 -NaN0 2 , and the components by weight of each component are: 30-60 parts of potassium nitrate; 40-70 parts of sodium nitrite.
  • the binary nitrate molten salt system is KN0 3 -NaN0 3 , and the components of the components are: potassium nitrate 40 parts; sodium nitrate 60 parts;
  • the binary nitrate molten salt system is KN0 3 -NaN0 2 , and the composition by weight of each component is: 55 parts of potassium nitrate; 45 parts of sodium nitrite.
  • the nitrate molten salt system comprises a ternary nitrate molten salt system formed by potassium nitrate, sodium nitrate and sodium nitrite, wherein the weight ratio of each component of the heat transfer and heat storage medium is: potassium nitrate: 20 to 60 parts; Sodium: 8 to 20 parts; sodium nitrite: 10 to 50 parts; nanoparticles: 1 to 5 parts.
  • the weight ratio of each component of the heat transfer and heat storage medium is: potassium nitrate: 30 to 45 parts; sodium nitrate: 12 to 15 parts; sodium nitrite: 20 to 40 parts; nanoparticles: 4 to 5 parts.
  • the nitrate molten salt system is composed of potassium nitrate, sodium nitrate, sodium nitrite and cerium nitrate.
  • the mass percentage of each component of the heat transfer and heat storage medium is: potassium nitrate 20%-60 %, sodium nitrate 10%-20%, sodium nitrite 10%-50%, lanthanum nitrate 5%-10%, the nanoparticles are 1%-5% of the total mass of the polybasic nitrate molten salt system.
  • the molten salt system is a carbonate molten salt system formed of potassium carbonate, sodium carbonate, lithium carbonate and sodium chloride.
  • the weight ratio of each component of the heat transfer and heat storage medium is: potassium carbonate 30 ⁇ 60 parts; sodium carbonate 20 ⁇ 50 parts; lithium carbonate 10 ⁇ 30 parts; sodium chloride 3 ⁇ 10 parts; nanoparticles: 1 ⁇ 5 servings.
  • a preparation method of a nano molten salt heat transfer and heat storage medium comprising the following steps:
  • the nanoparticles are SiO 2 , ZnO, Al 2 2 3 3 , Ti 0 2 , MgO or CaO nanoparticles, the nanoparticles having an average particle diameter of 10-30 nm;
  • the molten salt system is a nitrate molten salt system or a carbonate molten salt system.
  • the above method is characterized by the use of a mobile electric heat tracing (10), a solar heat collecting system (9), a molten salt tank (2) with an interlayer (13), a jet mill drier (3), a hot air generator (4) ), granulator (5), cooling unit (20), stirring unit (11), feeding port (12);
  • the molten salt tank (2), the jet mill dryer (3), the granulator (5), and the cooling device (20) are connected in series through a pipe;
  • the hot air generator (4) is pulverized by the pipe and the gas stream
  • the dryer (3) is connected in series;
  • the mobile electric heat tracing (10) and the solar heat collecting system (9) are connected in parallel with each other, and are respectively connected in series with the interlayer (13) through a pipe;
  • the stirring device (11) is disposed in the molten salt tank (2), and the feed port (12) is provided on the top of the molten salt tank (2).
  • the solar collector system (9) also leads to another pipe connected in series with the interlayer (13), which is provided with a high temperature storage tank (1).
  • the hot air generator (4) is a heat exchanger, and the interlayer (13), the heat exchanger, and the jet mill dryer (3) are sequentially connected in series through a pipe, and the heat exchanger is further connected to a blower. (15) Connected.
  • the apparatus further includes a cryogenic storage tank (18), the heat exchanger and the cryogenic storage tank (18) being connected in series via a conduit, the cryogenic storage tank (18) drawing a pump III (17) through a conduit, Pump III (17) takes out two pipes in series with the solar heat collecting system (9) and the mobile electric heat tracing (10); the pump III (17) and the solar heat collecting system (9) And a valve is provided between the pump III (17) and the mobile electric heat tracing (10) for controlling the flow direction of the heat carrier in the low temperature storage tank (18).
  • the nanoparticles used in the present invention are industrially pure, that is, industrial grades and higher purity materials can be used in the present invention, and the impurities contained therein have little effect on the efficacy in the present invention.
  • the nano-fused salt of the present invention can be widely used in the fields of industrial energy storage and solar thermal power generation technology.
  • the nano-molten salt heat transfer and heat storage medium provided by the invention has the nanoparticles uniformly distributed in the molten salt, and the nanoparticles in the mixed liquid are stably suspended in the high-temperature liquid state. Due to the large specific surface area and interfacial effects of the nanoparticles, the thermal conductivity and heat transfer area of the molten salt are greatly increased.
  • the large capillary force generated by the nanocavity adsorbs the molten salt into the matrix to control the size and distribution of the holes, thereby making the volume shrinkage small.
  • the action of the capillary force makes it difficult for the liquid nano-molten salt to overflow from the micropores, thereby solving the problem of fluidity when the high-temperature molten salt is melted.
  • Chinese invention patent application 200910074994.0 discloses a fluorine salt-based nano high temperature phase change heat storage composite material, which is obtained by compounding nanometer gold particles, silver particles and copper particles into a high temperature phase change fluoride salt in a certain ratio, and overcomes Fluoride-based phase change materials have poor heat transfer properties, low thermal conductivity, and large volume shrinkage during solidification; however, gold particles and silver particles are expensive and are not suitable for large-scale industrial use; copper ions are used as metal elements. Stability is not as good as copper at high temperatures Metal oxide.
  • a molten salt system is added to metal oxide or non-metal oxide nanoparticles to improve the performance of the molten salt system.
  • the problems of each molten salt system are different, and the defects of each molten salt system and the fluorine molten salt system are different. Therefore, the technical means adopted for solving the defects of each molten salt system will be different.
  • the invention adds a metal oxide and/or non-metal oxide nano particle with high thermal conductivity to the molten salt to prepare a composite phase change molten salt material, which reduces the volume shrinkage ratio of the high temperature phase change heat storage material and the heat transfer and heat storage medium.
  • the melting point of the phase change material also increases the latent heat of phase change of the phase change material, improves the thermal conductivity of the heat transfer and heat storage medium of the present invention, and lowers the melting point of the heat transfer and heat storage medium of the present invention while ensuring a higher safe upper limit temperature.
  • the temperature of the heat transfer and heat storage medium of the present invention is widened.
  • the preparation method comprises the steps of heating and stirring of the molten salt, degassing and removing water, adding nanoparticles, and continuing heating, stirring, heat preservation and cooling of the obtained system.
  • the nanoparticles used in the present invention can also be self-prepared nanoparticles.
  • the metal oxide nanoparticles or non-metal oxide nanoparticles can be prepared by physical methods, gas phase methods, or chemical methods.
  • the physical method is a physical pulverization method and a mechanical ball milling method, and the physical pulverization method obtains nanoparticles by mechanical pulverization, electric spark explosion or the like. Its characteristics are simple in operation and low in cost, but the product has low purity and uneven particle distribution.
  • the ball milling method is used to control the appropriate conditions to obtain nanoparticles of pure elements, alloys or composite materials. Its characteristics are simple in operation and low in cost, but the product has low purity and uneven particle distribution.
  • the gas phase method is formed by adsorbing and cooling a material forming gas under certain conditions.
  • the chemical method is obtained by chemically reacting two or more substances at a certain temperature and pressure, and extracting, distilling, and drying.
  • the data of the embodiment of the present invention show that the latent heat of phase change of the binary nitric acid nano-smelting salt heat transfer and heat storage medium is higher than that of the binary nitric acid molten salt without the addition of nanoparticles, and the storage energy density is high, and the size of the heat storage system is reduced.
  • the medium can utilize and control the formation of holes to enhance heat transfer, limit the volumetric shrinkage of the binary nitric acid molten salt during solid-liquid phase transition, and reduce the volumetric shrinkage of the binary nitrate molten salt without the addition of nanoparticles.
  • the melting point is not significantly lower than that of the original binary nitrate molten salt, it is reduced, but the addition of nanoparticles greatly improves the thermal conductivity and thermal stability of the binary nitrate molten salt, avoiding the use of general high-temperature molten salt.
  • the defect of easy local overheating greatly broadens the operating temperature range of the binary nitrate molten salt system, and can be widely used in the fields of industrial energy storage and solar thermal power generation technology.
  • the inventors of the present invention add a metal oxide and/or a non-metal oxide nanoparticle having a high thermal conductivity to a ternary nitric acid molten salt to prepare a composite phase change molten salt material, which reduces the volume shrinkage of the material at a high temperature phase change heat storage.
  • the ratio also increases the latent heat of phase change of the phase change material, improves the thermal conductivity of the heat transfer and heat storage medium of the present invention, but does not improve the melting point of the heat transfer and heat storage medium of the present invention, and ensures the heat transfer and heat storage medium of the present invention.
  • the upper limit use temperature is increased, so that the use temperature of the heat transfer heat storage medium of the present invention is widened.
  • the ternary nitric acid nano-molten salt heat transfer and heat storage medium of the invention overcomes the disadvantages of low working temperature of the upper limit of the ternary nitrate molten salt, low heat of dissolution and low thermal conductivity, and solves the problem of LiN0 in Chinese patent 00111406.9 and US patent US007588694B1. 3
  • the high temperature composite ternary nitrate nanometer molten salt of the invention has the melting point as low as 120 ° C, the upper limit use temperature is up to 600 ° C, has good thermal stability and high thermal conductivity, and is very suitable for industrial energy storage and solar thermal power generation. Heat storage heat transfer system.
  • the ternary nitric acid nano-smelting salt heat transfer and heat storage medium of the invention not only has the heat transfer performance of the molten salt of nitric acid, but also improves the safe working temperature, the upper limit of the use temperature is up to 600 ° C, the use temperature range is wider, and the thermal stability it is good;
  • the ternary nitric acid nano-smelting salt heat transfer and heat storage medium of the invention has large latent heat of phase change, high energy storage density, low requirement on size and energy of the heat storage system, high energy utilization rate and good energy saving effect;
  • the ternary nitric acid nano-smelting salt heat transfer and heat storage medium of the invention maintains the lower limit use temperature of the general ternary nitrate molten salt, which is beneficial to reducing the heat preservation energy and preventing the molten salt from condensing in the pipeline;
  • the ternary nitric acid nano-smelting salt heat transfer and heat storage medium of the invention has good heat absorption and heat storage capacity, the thermal conductivity is obviously improved, the thermal conductivity is greatly increased, and the shortcomings of poor thermal conductivity of the ternary nitrate molten salt and local overheating are overcome. Can be widely used in the field of solar thermal power generation technology.
  • the multi-nitrate nano-melt salt heat transfer and heat storage medium prepared by the invention not only has the heat transfer performance of the molten salt of nitric acid, but also increases the upper limit of the safe working temperature to 600 ° C, has a wider use temperature range and good thermal stability.
  • the latent heat of phase change of the carbonic acid nano-melt salt heat transfer and heat storage medium can be as high as 300 J/g, and the latent heat of phase change is greatly improved compared with the carbonate molten salt without adding nanoparticles, and the energy storage density is high and decreased.
  • the requirements for the size of the heat storage system are high, and the energy efficiency is good.
  • the medium can utilize and control the formation of holes to enhance heat transfer, limit the volumetric shrinkage of the carbonate molten solid phase transition, and reduce the volume shrinkage by about 14% compared to the carbonate molten salt to which no nanoparticles are added.
  • the carbonic acid nano-fusing salt heat transfer and heat storage medium has good heat absorption and heat storage capacity, and the thermal conductivity is obviously improved.
  • the upper limit use temperature is 800 ° C, and the melting point is as low as 260 ° C, which overcomes the poor thermal conductivity of the carbon nano-fused salt.
  • the disadvantage of local overheating can be widely used in the field of
  • the upper limit is high in temperature, low in melting point, the upper limit is up to 800 °C, and the melting point is as low as 260 °C, which is beneficial to reduce the heat storage energy and prevent the molten salt from condensing in the pipeline;
  • the lower limit temperature is lower, the requirements on the size and energy of the system are not high, the energy utilization rate is high, and the energy saving effect is good;
  • the volume shrinkage ratio is small, and the volume shrinkage of the molten carbonate without the addition of nanoparticles is reduced by about 14%;
  • the latent heat of phase change is large, up to 300J/g, which is greatly improved compared with the latent heat of carbonate carbonate molten salt without the addition of nanoparticles.
  • the energy storage density is high, which can meet the high temperature heat utilization of solar energy, and is very suitable for solar thermal power. Power generation system, solar thermal A heat storage heat transfer system for power generation.
  • the apparatus used to prepare the nano-molten salt of the present invention is as follows:
  • the device comprises a mobile electric heating (10), a solar collector system (9), a molten salt tank (2) with a sandwich (13), a jet mill dryer (3), a hot air generator (4), Granulator (5), cooling device (20), stirring device (11), feed port (12);
  • the molten salt tank (2), the jet mill dryer (3), the granulator (5), and the cooling device (20) are connected in series through a pipe; the hot air generator (4) is pulverized by the pipe and the gas stream
  • the dryer (3) is connected in series; the mobile electric heat tracing (10) and the solar heat collecting system (9) are respectively connected in series with the interlayer (13) through a pipe; mobile electric heat tracing (10) or solar energy
  • the heat collecting system (9) heats the heat carrier and heats the molten salt tank (2) to prepare a high-temperature molten salt, and the prepared high-temperature molten salt flows through the pipe from the upper end of the jet mill dryer (3), and the hot air generator (4)
  • the generated hot air flows from the lower end of the jet mill dryer (3) to achieve the purpose of drying and pulverizing the high-temperature molten salt, and the dried high-temperature molten salt is placed in the granulator (5) for granulation.
  • the high temperature molten salt is obtained by
  • the stirring device (11) is disposed in the molten salt tank (2), and the stirring device (11) is a mechanical stirring device for agitating and mixing during large-scale preparation of molten salt, the feeding port ( 12) is disposed on the top of the molten salt tank (2) to facilitate the addition of the raw material components of the molten salt from above.
  • the solar collector system (9) also leads to another pipe connected in series with the interlayer (13), which is provided with a high temperature storage tank (1).
  • a valve is disposed between the solar heat collecting system (9) and the high temperature storage tank (1) for controlling whether the heat carrier in the solar heat collecting system 9 flows into the high temperature storage tank (1);
  • the solar collector system (9) or the mobile electric heat tracing (10) can be used to directly heat the heat carrier to heat the molten salt tank (2) ) to prepare high-temperature molten salt; when sufficient energy or molten salt tank (2) does not require heating, the valve between the solar collector system (9) and the high-temperature storage tank (1) can be opened, through the solar collector system (9)
  • the heated heat carrier can be stored in the high temperature storage tank (1) through the pipeline and stored.
  • the pump (19) can be pumped into the interlayer (13) to heat the molten salt tank (2) to prepare high temperature. Molten salt.
  • the hot air generator (4) is a heat exchanger, and the interlayer (13), the heat exchanger, and the jet mill dryer (3) are sequentially connected in series by a pipe, and the heat exchanger is further connected to a blower. (15) Connected. After the preparation of the high-temperature molten salt, the heat carrier in the interlayer (13) flows through the pipe to the heat exchanger and is used to heat the air that is blown into the heat exchanger by the blower (15), and the heated air is pulverized from the airflow through the pipe. The lower part of the dryer (3) flows into the high-temperature molten salt for drying from above, thereby realizing the reuse of the heat carrier in the interlayer (13), saving energy and environmental protection.
  • the apparatus further includes a cryogenic storage tank (18), the heat exchanger and the cryogenic storage tank (18) are connected in series through a pipe, and the other end of the low temperature storage tank (18) leads a pump III (17) through a pipe.
  • the pump III (17) leads two pipes respectively connected in series with the solar heat collecting system (9) and the mobile electric heat tracing (10); the pump III (17) and the sun A heat collecting system (9) and a pottery door between the pump (17) and the mobile electric heat tracing (10) are respectively provided for controlling the heat carrier in the low temperature storage tank (18) Flow direction.
  • the heat carrier flowing out of the interlayer (13) is heated by the air blown out by the blower (15) and then flows through the pipe to the low temperature storage tank (18), and the heat carrier from the low temperature storage tank (18) can pass through the two-way pipe.
  • flowing to the mobile electric heat tracing (10) which is heated to be used to heat the molten salt tank for preparing the high-temperature molten salt to prepare the high-temperature molten salt; or to the solar heat collecting system energy (9), the flow to the solar heat collecting system
  • the heat carrier of (9) is stored in a high-temperature storage tank for subsequent heating to prepare a high-temperature molten salt, or directly used for heating to prepare a high-temperature molten salt.
  • the device further comprises a silo (6), a packaging device (7) and a storage device (8); the silo (6), the packaging device (7) are connected in series by a pipe, the packaging device (7) and the storage device ( 8) phase in series; the molten salt granulated by the above granulation device (5) is cooled and temporarily stored in a silo (6), and then packaged using a packaging device (7), and finally stored using a storage device (8). spare.
  • a pump I (14) is disposed between the molten salt tank (2) and the jet mill dryer (3), and a pump II (16) is disposed between the heat exchanger and the cryogenic storage tank (18).
  • a pump IV (19) is provided between the high temperature storage tank (1) and the hot interlayer (13); the pump I (14) is used to pass the molten salt prepared in the molten salt tank (2) through the pipeline Pumping the top of the jet mill dryer (3); pump II (16) is used to pump the heat carrier from the heat exchanger into the cryogenic storage tank (18); pump IV (19) is used to store the high temperature storage tank ( 1) The high-temperature heat carrier is drawn into the interlayer (13) through a pipe and then heated to melt the salt can (2) to prepare a melt.
  • the solar heat collecting system (9) adopts a trough type, a tower type, a dish type or a linear Fresnel type solar thermal power generation mode. From the perspective of cost and technical maturity, the trough type and the tower type are preferred.
  • the trough mirror field of the photothermal power generation is selected as the method of collecting solar energy
  • the molten salt tank is directly heated by the high temperature heat carrier in the heat collecting tube.
  • the common high-temperature heat carriers are high-temperature molten salt, heat-conducting oil, and superheated steam, and heat-transfer oil is preferred in the trough mirror field.
  • the molten salt tank is directly heated by the high temperature heat carrier in the heat absorber.
  • the common high temperature heat carrier is a high temperature molten salt, a heat transfer oil, a superheated water vapor, and a molten salt is preferred in the tower mirror field.
  • a valve is arranged between the molten salt tank (2) and the pump I (14), and the wide door is used for controlling whether the high temperature molten salt in the molten salt tank (2) flows through the pipeline to the airflow pulverizing dryer (3)
  • the heat carrier is a high temperature molten salt, a heat transfer oil, and a superheated steam.
  • the device is designed with two heating systems, namely a solar collector system (9) and a mobile electric heat tracing (10).
  • a solar collector system (9) can be used, and the obtained high-temperature heat carrier can be partially
  • the molten salt can is directly heated, and the other part can be directly stored to meet the demand for the heat carrier when the solar energy is insufficient.
  • mobile electric heat tracing (10) can also be used to ensure that the device is used when the solar radiation is insufficient.
  • the preparation device makes full use of natural energy, and is energy-saving and environmentally friendly.
  • the preparation method of the invention can select a heating type electric heating or solar heat collecting according to a specific case.
  • the method also makes full use of the residual heat of the heat carrier in the molten salt tank interlayer to heat the required hot air through the heat exchange device.
  • the heat carrier in the heat exchange device heats the air, can flow into the low temperature energy storage tube through the pipeline, and then flows to the solar heat collecting system for the mobile electric heat tracing, and is then heated, and then used to heat the molten salt tank to prepare the high temperature carbonic acid nanometer.
  • Molten salt realizes the recycling of heat carrier, reduces cost, saves energy and protects the environment.
  • the liquid phase molten salt mixed system obtained in the method of the present invention directly forms a dry and uniform powder after passing through a jet mill drier, and is convenient for packaging and sale on the one hand. On the other hand, the performance is uniform and stable when used.
  • Figure 1 is a schematic view showing the structure of the apparatus used in the method of the present invention.
  • the reference numerals are listed as follows: 1-high temperature storage tank, 2-melting salt tank, 3-air pulverizing dryer, 4 hot air generator, 5-granulator, 6- silo, 7-packing device, 8 -Storage device, 9-Solar heat collector system, 10-mobile electric heat tracing, 11-stirring device, 12-feed port, 13-interlayer, 14-pump I, 15-blower, 16-pump II, 17- Pump III, 18-low temperature storage tank, 19-pump IV, 20-cooling unit.
  • Potassium carbonate, sodium carbonate, lithium carbonate, sodium chloride, potassium nitrate, sodium nitrate, sodium nitrite, cerium nitrate, silicon dioxide, zinc oxide, aluminum oxide, titanium dioxide, magnesium oxide, calcium oxide, etc. are all industrial pure Level, commercially available, available from general chemical companies.
  • the nanoparticles in the present invention may be obtained by a commercially available route or may be prepared by themselves, as long as the selected SiO 2 nanoparticles, ZnO nanoparticles, A1 2 3 3 nanoparticles, Ti 2 2 nanoparticles, MgO nanoparticles, CaO nanoparticles are selected.
  • the object of the present invention can be attained by an average particle diameter in the range of 10 to 30 nm.
  • the preparation of the nanoparticles can be carried out by using a gas phase method or a nanoparticle prepared by a physical method and a chemical method, and commercially available ones can achieve the object of the present invention, as long as the particle diameter of the selected nanoparticles is in the range of 10 to 30 nm. can.
  • the preparation method of the nanometer molten salt heat transfer and heat storage medium of the invention is as follows: 1) Proportionally compose the molten salt system, and add the molten salt tank from the feeding port, open the valve between the interlayer and the solar collector system, and the heat carrier heated by the solar collector system is statically heated to the interlayer to be melted in the molten salt tank.
  • the salt system is degassed and dehydrated to make it into a molten state, and the heating temperature is about 50 to 100 ° C above the molten salt phase transition temperature, and the temperature is kept for 10 to 30 minutes;
  • step 2) Open the discharge port of the molten salt tank, and then step 2) the molten salt is pumped into the airflow pulverizer by the molten salt pump, and the high temperature heat carrier in the molten salt tank is heated by the heat exchange device to obtain the required hot air. Then, the hot air is flowed into the airflow pulverizer from the bottom of the airflow pulverizing drying tower, and the granulated and cooled nano-salt heat transfer and heat storage medium is uniformly and stably cooled.
  • step 4) Put the nano-melt salt heat transfer and heat storage medium obtained in step 3) into the silo, and store and store.
  • the device used in the embodiment is a device developed by the inventor, and the device is provided with two sets of heating devices, including mobile electric heat tracing and solar heat collecting. In the production process, heating can be selected according to specific conditions. the way.
  • the heat carrier in the molten salt tank interlayer may be a high temperature heat transfer oil or a molten salt or superheated steam; when these heat carriers heat the molten salt in the molten salt tank, the remaining heat is fully utilized to flow to the heat exchanger. Heat hot air.
  • thermostability test was carried out on the preparation of the binary nitric acid nano-molten salt and the control (the original binary nitric acid molten salt of each binary nitric acid nano-molten salt).
  • the test is carried out by gravimetric method: the molten salt sample to be tested is added to different nickel crucibles, heated in a temperature controlled furnace, weighed by an analytical balance, and the experiment is started from a normal temperature, and then statically heated until the solid is completely melted. Each period of time was naturally cooled to room temperature and the test mash was taken out and weighed using an analytical balance. If the weight of the sample is no longer reduced within a certain temperature range, increase the temperature of the temperature control furnace. The test was then taken at regular intervals and weighed with an analytical balance until another steady state followed by warming. In this cycle, the specific holding temperature and holding time are recorded, and the loss rate and residual rate corresponding to the specific holding temperature and holding time are calculated.
  • Example 1 prepared binary nitric acid nano-molten salt
  • the binary nitrate nano-KN0 3 -NaN0 3 molten salt system is a heavy t-nanoparticle type and its proportion of the molten salt number (also a control) KN0 3 -NaN0 3 molten salt system
  • the melting point test results of 1) show that, as shown in Table 2, the melting point of No. ll ⁇ 15 product is lower than that of the corresponding control, but it is not obvious.
  • phase change has a latent heat and the melting point is too high
  • metal oxide nanoparticles at 565 ° C can significantly improve the thermal stability of each group of products relative to the control.
  • thermostability test was carried out on the preparation of the binary nitric acid nano-molten salt and the control (the original binary nitric acid molten salt of each binary nitric acid nano-molten salt).
  • Example 2 prepared binary nitric acid nano-molten salt
  • Table 9 is a formulation of each group of ternary nitric acid nano-molten salt according to the embodiment, and a particle diameter of the nanoparticles in the formulation, and a molten salt of the nitrate obtained by adding a fourth component to the ternary nitrate molten salt according to the prior art.
  • the Chinese invention patent No. 200710027954.1 discloses a molten salt heat transfer and heat storage medium and a preparation method thereof, and XI is an additive-added nitric acid obtained by the inventor of the patent according to the formulation and preparation method described in the first embodiment of the specification.
  • the Chinese invention patent No. 00111406.9 discloses a mixed molten salt of Lihe (LiN0 3 -KN0 3 -NaN0 3 -NaN0 2 ) and a preparation method thereof, and X2 is a formulation and preparation according to the application document of the patent inventor.
  • the quaternary nitrate nitrate salt obtained by the method.
  • Table 9 The ternary nitric acid nano-molten salt formula of Example 3 and the particle size of the corresponding nano-particles, the three-dimensional sodium nitrate nitrate nitrate molten salt, the weight fraction, the nanoparticle type and the weight ratio / kg, the bare nanometer square rice molten salt number Ratio / kg average particle size /
  • Example 10 The test was carried out by the gravimetric method (method same as in Example 1): XI, X2 and the ternary nitric acid nano-smelting salt group No. 1 to 25 of Example 3 of the present invention were respectively tested by the method, and Table 10 was obtained based on the test data.
  • the ternary nitric acid nano-smelting salt group of the third embodiment of the present invention ⁇ .1 ⁇ .10 ternary nitric acid nano-molten salt heat transfer and heat storage
  • the loss of components caused by the decomposition of the mass is relatively small; when the operation temperature is 600 ° C for 46 hours, the loss rate of the XI and X2 components is 30% and 31%, respectively.
  • the nitrate nitric acid nano-smelting salt group ⁇ .1 ⁇ .10 ternary nitrate nano-molten salt heat transfer heat storage medium component loss also increases.
  • the ternary nitrate nano-molten salt heat transfer medium prepared by the ternary nitric acid nano-smelting salt group ⁇ .10 ⁇ .25 of the third embodiment of the present invention has a significant decrease in component loss at various experimental temperatures. Basically stable operation at 120-600 °C.
  • the heat transfer and heat storage medium of the ternary nitrate nano-smelting salt group ⁇ .10 ⁇ .25 has substantially no component loss at 120-600 °C.
  • the ternary nitrate nano-smelting salt group ⁇ .10 ⁇ .25 process conditions of the third embodiment of the present invention and the ternary nitrate molten salt of the formulation of the third embodiment of the present invention are added with specific particle diameters and specific The amount of nanoparticles can effectively improve the stability of the molten salt heat transfer and heat storage medium at 600 ° C.
  • the sample melted salt was subjected to the lowest melting temperature and phase change latent heat test using a universal differential scanner (DSC).
  • the test results are shown in Table 3.
  • the results show that the minimum melting temperature and latent heat of phase change of the ternary nitrate nano-molten salt prepared by the ternary nitric acid nano-molten salt group No. 1 to No. 25 of the embodiment 3 of the present invention are different from those of the prior art XI and X2.
  • the latent heat of phase change is increased, so that the lower limit use temperature of the ternary nitric acid nano-smelting salt heat transfer and heat storage medium of the third embodiment of the present invention can be maintained, and the safe upper limit use temperature is increased, so that the present invention is
  • the ternary nitric acid nano-molten salt heat transfer medium of Example 3 has a widened use temperature.
  • Phase-change volume shrinkage of the ternary nitric acid nano-molten salt heat transfer and heat storage medium prepared by the ternary nitric acid nano-molten salt group No. 1 to No. 25 of Example 3 of the present invention compared with the ternary nitrate molten salt The rate is reduced and the thermal conductivity is increased.
  • Table 11 The specific data of the phase change volume shrinkage reduction of the ternary nitric acid nano-molten salt heat transfer and heat storage medium prepared by No. 1 - No. 25 of Example 3 of the present invention is shown in Table 11.
  • the performance test methods and procedures adopt the above methods and steps.
  • the test results are shown in Table 11, wherein the percent change in latent heat of phase change and the percentage decrease in volume shrinkage are compared with ordinary ternary nitrate molten salt KN0 3 -NaN0 3 -NaN0 2 , respectively.
  • the relative kinetic latent heat and volume shrinkage of the ordinary ternary nitrate molten salt KN0 3 -NaN0 3 -NaN0 2 is 1, the ternary nitrate nano-smelting salt group No. 1 to No.
  • the ternary nitric acid nano-smelting salt heat transfer and heat storage medium of the present invention is basically maintained at a low minimum melting temperature as compared with the XI and X2 molten salt heat transfer and heat storage medium.
  • the use temperature of the ternary nitric acid nano-smelting salt heat transfer and heat storage medium of Embodiment 3 of the present invention is ensured.
  • the ternary nitric acid nano-smelting salt heat transfer and heat storage medium of the embodiments of the present invention has improved phase change latent heat, and the volume shrinkage ratio is reduced.
  • the invention reduces the volume shrinkage of the molten salt material during phase transformation by adding nanoparticles in the system of the ternary nitrate molten salt, and reduces the volume shrinkage ratio of the ternary nitrate nanometer molten salt heat transfer and heat storage medium, and improves the volume shrinkage ratio.
  • the thermal conductivity of the ternary nitric acid nano-molten salt heat transfer and heat storage medium of the invention By carefully comparing the data of Table 11, it can be seen that the heat transfer medium of the ternary nitric acid nano-molten salt group No. ll ⁇ No. 25 of the embodiment 3 of the present invention has a lower minimum melting temperature, a latent heat of phase change and a volume. The shrinkage is more than the reduced value.
  • the heat transfer and heat storage medium of the ternary nitric acid nano-molten salt No. ll ⁇ No. 25 of the third embodiment of the present invention has better performance indexes.
  • Example 4 Preparation steps of multi-nitrate nano-molten salt
  • Table 12 The ratio of Table 12 below is a series of polybasic nitric acid nano-molten salts of Example 4.
  • Table 12 shows the formulation of the different numbered polynitrate nano-molten salts of the present embodiment and the particle size of the nanoparticles in the formulation.
  • thermo-stability tests of the multi-nitrate nano-molten salt shown in Table 12 and the control XI and the control X2 were carried out by the above methods, and the test results are shown in Table 13.
  • the stable temperature limit of the control XI is 550 ° C, the temperature is maintained at 550 ° C for 30 hours, the loss rate is about 4%, and the loss rate is about 14% when the temperature is kept for 50 hours;
  • the stable temperature limit of the control X2 is 550 ° C, 550 ° C for 30 hours, loss rate of about 3%, the loss rate of about 16% when kept at 50 hours; and the preparation of the multi-nose nitric acid nano-molten salt No.l- No. 25 at 600 ° C
  • the loss rate is comparable to the control loss rate at 550 ° C. This result indicates that the product of the present invention has better thermal stability and can be stably operated at 600 ° C for a longer period of time.
  • the sample melted salt was subjected to the lowest melting temperature and phase change latent heat test using a universal differential scanner (DSC). The test results are shown in Table 14.
  • the multi-nano-nitrate nano-molten salt No. 1-No. 25 prepared by the present invention has a reduced phase-change volume shrinkage ratio and an improved thermal conductivity.
  • the specific data of the reduction of the phase change volume shrinkage of the polyhydric nitric acid nano-molten salt No.l-No. 25 heat-transfer heat storage medium prepared by the present invention is shown in Table 14.
  • the performance test methods and steps adopt the above methods and steps.
  • the test results are shown in Table 14, wherein the percent change in latent heat of phase change and the percentage decrease in volume shrinkage are compared with ordinary ternary nitrate molten salt KN0 3 -NaN0 3 -NaN0 2 , respectively.
  • the multi-nitrate nano-molten salt heat transfer and heat storage medium prepared by the present invention is maintained at a lower melting temperature than the XI and X2 molten salt heat transfer and heat storage medium, and the multi-nano-nitrogen nanometer of the present invention is ensured.
  • the molten salt heat transfer heat storage medium has a low use temperature.
  • the latent heat of phase change of the multi-nitrate nano-molten salt heat transfer and heat storage medium prepared by the invention is improved, and the volume shrinkage ratio is reduced.
  • the present invention limits the volume shrinkage of a molten salt material during phase transformation by reducing nanoparticles in a multi-nickel molten salt system, and reduces the volume shrinkage ratio of the multi-nitrate nano-molten salt heat transfer and heat storage medium, thereby improving the present invention.
  • the polyhydric nitric acid nano-molten salt No. 16-No. 25 heat transfer heat storage medium prepared by the invention has a lower minimum melting temperature, a higher phase change latent heat increase and a smaller volume shrinkage ratio. many.
  • the multi-nitrate nano-molten salt No. 16- No. 25 heat-transfer heat storage medium prepared by the invention has better performance indexes.
  • Example 5 Preparation method of carbonic acid nano molten salt heat transfer and heat storage medium 1) Preparation of metal oxide nanoparticles MgO and/or non-metal oxide nanoparticles Si0 2 by gas phase method (note that the nanoparticles in this step can be obtained by a commercially available route, and the commercially available nanoparticles can also realize the present invention. Purpose of the invention);
  • potassium carbonate and sodium carbonate are added to the molten salt tank, stirred to make the mixture uniform, and the carbonated molten salt system is obtained, and then the heat carrier heated by the solar heat collecting system is used to statically heat the molten salt tank to degas and remove water to make it molten.
  • the heating temperature is about 50 ⁇ 100 °C above the molten salt phase transition temperature, and the temperature is kept for 10 ⁇ 30min;
  • step 1) adding the nanoparticles obtained in the step 1) to the above-mentioned molten salt tank, mechanically stirring the molten mixture for 0.5 to lh, so that the initial mixing is uniform, and the mixture is further stirred and mixed for 0.5 to 1 hour to be uniformly mixed to obtain a high-temperature molten salt;
  • step 3) Open the discharge port of the molten salt tank, and then step 3) the molten salt of molten salt is pumped into the airflow pulverizer by the molten salt pump, and the high temperature heat transfer oil in the molten salt tank is heated by the heat exchange device to obtain the required hot air. Then, the hot air is flowed from the bottom of the jet pulverization drying tower into the jet pulverizer to granulate a uniform and stable carbonic acid nano-smelting salt heat transfer and heat storage medium.
  • step 5 Put the carbonic acid nano-melt salt heat transfer and heat storage medium obtained in step 4) into a silo, and store and store.
  • the device used in the embodiment is a device developed by the inventor, and the device is provided with two sets of heating devices, including mobile electric heat tracing and solar heat collecting. In the production process, heating can be selected according to specific conditions. the way.
  • the heat carrier in the molten salt tank interlayer may be a high temperature heat transfer oil or a molten salt or superheated steam; when these heat carriers heat the molten salt in the molten salt tank, the remaining heat is fully utilized to flow to the heat exchanger. Heat hot air.
  • Table 15 shows the respective formulations of the carbonic acid nano-molten salt according to the preparation method of Example 5, and the particle diameter of the nanoparticles in the formulation, and the formulation of the molten salt according to the prior art (X3), wherein the application number is 200910037348.7
  • the Chinese invention patent discloses a lithium-containing carbonic acid molten salt heat transfer and heat storage medium and a preparation method thereof, and X3 is a lithium-containing carbonate molten salt obtained by the inventor of the invention according to the formulation and preparation method described in the fourth embodiment of the specification (not Containing nanoparticles);
  • the loss rate of the control X3 at 700 °C and below the loss rate is 0, when the temperature rises to 816 °C and the temperature is 40h, the loss rate is 1%, and when the temperature rises to 821 °C and keeps the temperature for 35h The time loss rate is 7%.
  • the carbonic acid nano-molten salt group of the present invention has a loss rate of 0 at a temperature of 70 CTC and below, and a loss rate of 1% or less when the temperature is raised to 816 ° C and maintained at 40 h. The loss rate was 0.8 to 1.7% when the temperature was raised to 821 ° C and kept at 35 h.
  • both the carbonic acid nano-molten salt group and the X3 carbonic acid molten salt of the embodiment of the invention can stably operate at a temperature of 800 ° C, and the molten salt of the carbon nano-molten salt group of the invention has better thermal stability. Its residual rate at the corresponding temperature above 80 CTC is greater.
  • Phase change volume shrinkage test The carbonic acid nanometer prepared by the carbonic acid nano-molten salt group No. l ⁇ 25 of the present invention is compared with the carbonate molten salt of the control X3 by the method of testing the volumetric shrinkage conventionally used in the prior art.
  • the phase change volume shrinkage of the molten salt heat transfer and heat storage medium is reduced, and the thermal conductivity is improved.
  • the specific data of the phase change volume shrinkage reduction of the carbonic acid nano-molten salt heat transfer and heat storage medium prepared by the carbonic acid nano-molten salt group No. 1-25 of the present invention is shown in Table 17.
  • the performance test method and the procedure adopt the above methods and steps, and the test results are shown in Table 17, wherein the volume shrinkage percentage is compared with the ordinary carbonate molten salt X3, and the carbonic acid nano-molten salt prepared by the carbonic acid nano-molten salt group No. l ⁇ 25 of the present invention.
  • the respective volume shrinkage percentage values of the heat transfer heat storage medium are as follows.
  • the carbonic acid nano-melt salt heat transfer and heat storage medium prepared by the invention is maintained at a lower melting temperature than the ⁇ 3 molten salt heat transfer and heat storage medium, and the carbonic acid nano-molten salt of the present invention is ensured.
  • the heat storage medium has a low use temperature.
  • the latent heat of phase change of the carbonic acid nano-melt salt heat transfer and heat storage medium prepared by the invention is greatly improved, which may be due to the change of the carbonate molten salt due to the addition of nanoparticles.
  • the carbonic acid molten salt of the present invention which is caused by the structure of the matrix, simultaneously with the addition of the nanoparticles, also limits the large volume shrinkage in the solid-liquid phase change, and the volume shrinkage ratio is reduced by nearly 10% compared to the ⁇ 3 carbonate molten salt to which no nanoparticles are added.
  • the present invention limits the volume shrinkage of a molten salt material during phase transformation by reducing nanoparticles in a common carbonate molten salt system, reduces the volume shrinkage ratio of the carbonic acid nano-smelting salt heat transfer and heat storage medium, and improves the carbonic acid of the present invention.
  • the thermal conductivity of the nano-fused salt heat transfer heat storage medium In general, the carbonic acid nano-molten salt ⁇ . 1 ⁇ 25 of the carbonic acid nano-molten salt group of the invention has better performance indexes of the carbonic acid nano-molten salt heat transfer and heat storage medium.
  • the nano-smelting salt heat transfer and heat storage medium listed in the embodiment of the present invention is used as a method for using solar thermal power generation, and can be used as a method for using solar thermal power generation by referring to a nitric acid molten salt heat transfer and heat storage medium in the prior art.
  • the nano-melt salt heat transfer and heat storage medium of the invention can also reduce the auxiliary heat preservation equipment, the measures and the equipment for preventing the solidification of the molten salt heat transfer heat storage medium on the basis of the original equipment, and reduce the investment cost of the solar thermal power generation. .

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Abstract

本发明提供一种纳米熔盐传热蓄热介质及其制备方法与应用，属于热量储存及传递技术领域。本发明的纳米熔盐传热蓄热介质是将金属氧化物纳米粒子和/或非金属氧化物纳米粒子分散到常规的熔盐体系，复合形成纳米熔盐传热蓄热介质。本发明提供的传热蓄热介质热稳定性好，导热性能高，非常适合用于工业蓄能、太阳能光热发电的蓄热传热系统。

Description

说明书 一种纳米熔盐传热蓄热介质及其制备方法与应用 技术领域
本发明涉及热量储存及传递技术领域，尤其涉及一种纳米熔盐传热蓄热介质及其制备方法 与应用。
背景技术
在工业蓄能和太阳能高温蓄热技术中， 目前使用的蓄热传热介质主要有空气、水、导热油、 熔融盐、钠和铝等金属。熔盐因具有广泛的使用温度范围，低蒸汽压，低粘度， 良好的稳定性， 低成本等诸多特性已成为太阳能光热发电技术中颇具潜力的传热蓄热介质， 成为目前应用较 多， 较为成熟的传热蓄热介质。高温熔融盐主要有硝酸盐、碳酸盐、硫酸盐、氟化物、氯化物、 氧化物等。
硝酸熔盐体系的突出优点是原料来源广泛、 价格低廉、 腐蚀性小， 因此与其他熔盐相比， 硝酸熔盐具有很大的优势。但是硝酸熔盐体系存在溶解热较小和热导率低的缺点，在高温下容 易分解。现有技术中研究人员尝试向硝酸熔盐体系中加入其它成分来解决上述问题，但是改善 后的硝酸熔盐体系的上限工作温度提高的同时，其下限工作温度也被提高， 导致云遮时维护成 本增大。碱金属碳酸盐熔点高、 热稳定性好、 上限使用温度高， 是太阳能高温利用范围的首选 熔盐材料。然而， 其下限使用温度也相应提高， 耗能也致使维护成本变高。 而氟盐熔盐的相变 潜热高， 并且通过不同熔点的氟盐的混合可以得到具有不同相变温度的蓄热介质， 从而在很宽 广的温度范围内满足空间太阳能热动力发电循环的要求。氟盐能满足其热力性能和相容性的要 求， 但其一个明显缺点是其导热率较低以及凝固时体积收缩大。
现有技术中尚未有能同时保证较高的上限工作温度高和较低的下限工作温度，同时具有较 高的导热率的熔盐体系。
发明内容
根据上述领域的缺陷和不足， 本发明提供一种纳米熔盐传热蓄热介质及其制备方法与应 用，本发明所述的纳米熔盐传热蓄热介质具有较高的导热率， 能保证整个体系的上限工作温度 高的同时， 也保证较低的下限工作温度， 有效降低了维护成本， 大大拓宽了熔盐体系的工作温 度范围， 可广泛用于工业蓄能和太阳能光热发电技术领域。
本发明的技术方案如下：
一种纳米熔盐传热蓄热介质， 其特征在于： 将金属氧化物纳米粒子和 /或非金属氧化物纳 米粒子分散到熔盐体系中复合而得。
所述纳米粒子为 Si02、 ZnO、 A1203、 Ti02 、 MgO禾 Π/或 CaO纳米粒子， 所述纳米粒子的 平均粒径为 10-30nm。
所述熔盐体系为硝酸熔盐体系。
所述硝酸熔盐体系为二元硝酸熔盐体系， 所述纳米粒子的重量在所述传热蓄热介质中占 1 %-5 ； 所述二元硝酸熔盐体系为 KN03-NaN03， 其各成分的重量份组成为： 硝酸钾 20-40 份； 硝酸钠 60-80份的二元硝酸熔盐体系 KN03-NaN03;
或所述二元硝酸熔盐体系为 KN03-NaN02, 各成分的重量份组成为： 硝酸钾 30-60份； 亚 硝酸钠 40-70份。
所述二元硝酸熔盐体系为 KN03-NaN03， 所述各成分的重量份组成为： 硝酸钾 40份； 硝 酸钠 60份；
或所述二元硝酸熔盐体系为 KN03-NaN02, 各成分的重量份组成为： 硝酸钾 55份； 亚硝 酸钠 45份。
所述硝酸熔盐体系为由硝酸钾， 硝酸钠， 亚硝酸钠形成三元硝酸熔盐体系， 所述传热蓄热 介质各组分重量份配比为： 硝酸钾： 20〜60份； 硝酸钠： 8〜20份； 亚硝酸钠： 10〜50份； 纳米粒子： 1〜5份。
所述传热蓄热介质各组分重量份配比为： 硝酸钾： 30〜45份； 硝酸钠： 12〜15份； 亚硝 酸钠： 20〜40份； 纳米粒子： 4〜5份。
所述硝酸熔盐体系为主要由硝酸钾、 硝酸钠、 亚硝酸钠和硝酸铯组成多元硝酸熔盐体系， 所述传热蓄热介质各成分的质量百分比含量分别为： 硝酸钾 20%-60%， 硝酸钠 10%-20%， 亚 硝酸钠 10%-50% , 硝酸铯 5%-10%， 所述纳米粒子为所述多元硝酸熔盐体系总质量的 1%-5%。
所述熔盐体系为由碳酸钾， 碳酸钠， 碳酸锂和氯化钠形成的碳酸熔盐体系。
所述传热蓄热介质各组分重量份配比为： 碳酸钾 30〜60份； 碳酸钠 20〜50份； 碳酸锂 10〜30份； 氯化钠 3〜10份； 纳米粒子： 1〜5份。
上述的纳米熔盐传热蓄热介质在工业蓄能或太阳能光热发电中的用途。
一种纳米熔盐传热蓄热介质的制备方法， 包括以下步骤：
( 1 ) 将熔盐体系加热使其成熔融状态；
(2) 将纳米粒子按比例加入到熔融的熔盐体系中， 搅拌均匀后保温， 得到高温熔融盐；
( 3) 将所述高温熔融盐冷却， 即得到纳米熔盐传热蓄热介质；
所述纳米粒子为 Si02、 ZnO、 A1203、 Ti02 、 MgO禾 或 CaO纳米粒子， 所述纳米粒子的 平均粒径为 10-30nm; 所述熔盐体系为硝酸熔盐体系或碳酸熔盐体系。
上述方法特征为使用包括移动式电伴热 （10)， 太阳能集热系统 （9)、 带夹层 （13) 的熔 盐罐 （2)， 气流粉碎干燥器 （3)， 热空气产生器 （4)， 造粒装置 （5)， 冷却装置 （20)， 搅拌 装置 （11)， 进料口 （12) 的装置；
所述熔盐罐（2)， 气流粉碎干燥器（3)， 造粒装置（5)， 冷却装置（20)通过管道依次串 联；所述热空气产生器（4)通过管道与所述气流粉碎干燥器（3)串联；所述移动式电伴热（10) 和所述太阳能集热系统 （9) 相互并联， 并分别通过管道与所述夹层 （13) 串联；
所述搅拌装置 （11)设于所述熔盐罐（2) 内， 所述进料口 （12)设于所述熔盐罐 （2)上 顶部。
所述太阳能集热系统 （9) 上还引出另一管道与夹层 （13)相串连， 该管道上设有高温储 存罐 （1)。
所述热空气产生器（4)为热交换器， 所述夹层（13)、 所述热交换器、 所述气流粉碎干燥 器 （3)通过管道依次串联， 所述热交换器还与一鼓风机 （15)相连。
所述装置还包括低温储存罐 （18)， 所述热交换器与所述低温储存罐 （18) 通过管道相串 联， 所述低温储存罐 （18)通过管道引出泵 III ( 17)， 所述泵 III ( 17) 引出两管道分别与所述 太阳能集热系统 （9) 以及所述移动式电伴热 （10) 相串连； 所述泵 III ( 17) 与所述太阳能集 热系统（9)， 以及所述泵 III ( 17)与所述移动式电伴热（10)之间分别设有阀门， 用于控制所 述低温储存罐 （18) 中的热载体的流向。
技术效果
本发明采用的纳米粒子符合工业纯级即可，也就是说，工业纯级以及更高纯级的材料都可 以用于本发明，并且其中含有的杂质对其在本发明中的功效影响不大。本发明的纳米熔盐可广 泛用于工业蓄能和太阳能光热发电技术领域。
本发明提供的纳米熔盐传热蓄热介质， 纳米粒子均匀分布在熔盐中， 在高温液相状态下， 混合液内的纳米粒子稳定悬浮。由于纳米粒子很大的比表面积和界面效应，大大增加了熔盐的 导热系数和传热面积。通过纳米空洞产生的巨大毛细管力将熔盐吸附到基体中来控制空穴的尺 度和分布， 从而使体积收縮变小。毛细管力的作用使液态的纳米熔盐很难从微孔中溢出， 从而 解决了高温熔盐熔化时的流动性问题。
中国发明专利申请 200910074994.0公开了一种氟盐基纳米高温相变蓄热复合材料， 是将 纳米级的金粒子、银粒子、铜粒子按一定比例复合到高温相变的氟盐中得到的， 克服了氟盐基 相变材料存在的传热性能差， 导热率低， 凝固时体积收缩大等缺陷； 但是金粒子、银粒子价格 昂贵，不适合用于大规模工业化使用； 铜离子作为金属单质其在高温状态下稳定性又不如铜的 金属氧化物。现有技术中并未有熔盐体系加入金属氧化物或非金属氧化物纳米粒子从而改善熔 盐体系性能的报道。 同时， 各熔盐体系存在的问题各不相同， 以及各熔盐体系与氟熔盐体系的 缺陷也不相同， 因此， 考虑解决各熔盐体系的缺陷所采用的技术手段便会各不相同。
本发明在熔盐中加入导热系数高的金属氧化物和 /或非金属氧化物纳米粒子， 制备复合相 变熔盐材料， 降低了高温相变蓄热材料的体积收縮比和传热蓄热介质的熔点， 同时也提高了相 变材料的相变潜热，提高了本发明传热蓄热介质的导热率，在保证本发明传热蓄热介质较高的 安全使用上限温度的同时， 降低其熔点， 使得本发明传热蓄热介质使用温度变宽。
制备方法包括熔盐的加热搅拌、除气除水、添加纳米粒子、所得体系继续加热搅拌、保温、 冷却等工序。
本发明中所用到的纳米粒子也可采用自行制备的纳米粒子。制备金属氧化物纳米粒子或非 金属氧化物纳米粒子可以采用物理法， 气相法， 化学法。其中物理法为物理粉碎法和机械球磨 法， 物理粉碎法通过机械粉碎、 电火花爆炸等方法得到纳米粒子。 其特点操作简单、 成本低， 但产品纯度低， 颗粒分布不均匀。采用球磨方法， 控制适当的条件得到纯元素、合金或复合材 料的纳米粒子。 其特点操作简单、成本低， 但产品纯度低， 颗粒分布不均匀。气相法是把材料 形成气体在一定条件下吸附冷却而成。化学法是通过两种或两种以上的物质在一定的温度压力 下化学反应而成， 并通过萃取、 蒸馏、 干燥而得。
本发明实施例数据显示，二元硝酸纳米熔盐传热蓄热介质的相变潜热比没有加入纳米粒子 的二元硝酸熔盐相变潜热高， 储能密度高， 降低了对蓄热系统尺寸的要求， 能量利用率高， 节 能效果好。该介质可以利用和控制空穴的形成以强化传热， 限制二元硝酸熔盐固液相变时的体 积收縮， 比没有加入纳米粒子的二元硝酸熔盐的体积收縮减少。 虽然其相比原二元硝酸熔盐， 熔点降低不显著，但都有所降低，但是纳米粒子的加入大大提高了二元硝酸熔盐的导热系数和 热稳定性，避免了一般高温熔盐使用时容易局部过热的缺陷，大大拓宽了二元硝酸熔盐体系的 工作温度范围， 可广泛用于工业蓄能和太阳能光热发电技术领域。
本发明发明人在三元硝酸熔盐中加入导热系数高的金属氧化物和 /或非金属氧化物纳米粒 子， 制备的复合相变熔盐材料， 降低了高温相变蓄热才材料的体积收缩比， 同时也提高了相变 材料的相变潜热，提高了本发明传热蓄热介质的导热率，但是并没有提高本发明传热蓄热介质 的熔点， 在保证本发明传热蓄热介质低熔点的同时， 提高其上限使用温度， 使得本发明传热蓄 热介质使用温度变宽。
本发明的三元硝酸纳米熔融盐传热蓄热介质克服了三元硝酸熔盐上限工作温度偏低、溶解 热小、热导率低的缺点，解决了中国专利 00111406.9和美国专利 US007588694B1中由于 LiN03 存在所引起的腐蚀和成本增加问题， 还解决了中国专利 201110425668.7 中 KN03-NaN03-Ca (N03 ) 2体系中硝酸钙热稳定性差的问题。 本发明的高温复合三元硝酸纳米熔融盐的熔点最 低至 120°C， 上限使用温度最高达 600°C， 热稳定性好， 导热性能高， 非常适合用于工业蓄能、 太阳能光热发电的蓄热传热系统。
本发明三元硝酸纳米熔盐传热蓄热介质具有如下的优点和积极效果：
1.本发明三元硝酸纳米熔盐传热蓄热介质既有硝酸熔盐的传热性能， 又提高了安全工 作温度， 使用温度上限最高达 600°C， 使用温度范围更宽， 热稳定性好；
2.本发明三元硝酸纳米熔盐传热蓄热介质相变潜热大， 储能密度高， 降低了对蓄热系 统尺寸和能量的要求， 能量利用率高， 节能效果好；
3.本发明三元硝酸纳米熔盐传热蓄热介质保持了一般三元硝酸熔盐低的下限使用温 度， 有利于降低保温能耗， 防止熔盐在管路中凝结；
4.本发明三元硝酸纳米熔盐传热蓄热介质吸热及蓄热能力好， 导热系数明显提高， 导 热性能大大增加， 克服了三元硝酸熔盐导热性能差， 易局部过热的缺点， 可广泛用于太阳 能光热发电技术领域。
本发明制备的多元硝酸纳米熔盐传热蓄热介质既有硝酸熔盐的传热性能，又提高了安全工 作温度上限至 600°C， 使用温度范围更宽， 热稳定性好。
本发明碳酸纳米熔盐传热蓄热介质的相变潜热大， 可高达 300J/g， 与没有加入纳米粒子的 碳酸熔盐相比， 其相变潜热得到大幅的提高， 储能密度高， 降低了对蓄热系统尺寸的要求， 能 量利用率高， 节能效果好。该介质可以利用和控制空穴的形成以强化传热， 限制碳酸熔盐固液 相变时的体积收缩， 比没有加入纳米粒子的碳酸熔盐的体积收縮减少 14%左右。 本发明碳酸 纳米熔盐传热蓄热介质的吸热及蓄热能力好， 导热系数明显提高， 上限使用温度 800°C， 熔点 低至 260°C， 克服了碳酸纳米熔盐导热性能差、 易局部过热的缺点， 可广泛用于太阳能光热发 电技术领域。
本发明碳酸纳米熔盐传热蓄热介质具有如下的优点和积极效果：
1.热稳定性好、 导热性能好、 吸热、 蓄热能力好， 导热系数高， 克服普通碳酸熔盐易局部 过热的缺点；
2.上限使用温度高， 熔点低， 上限使用温度高达 800°C， 熔点低至 260°C， 有利于降低保 温能耗， 防止熔盐在管路中凝结；
3.下限温度较低， 对系统的尺寸和能量的要求不高， 能量利用率高， 节能效果好；
4.体积收缩比小， 比没有加入纳米粒子的碳酸熔盐的体积收缩减少 14%左右；
5.相变潜热大， 可高达 300J/g， 相比没有加入纳米粒子的碳酸熔盐相变潜热有很大提高， 储能密度高， 能够满足太阳能高温热利用， 非常适合用于太阳能热动力发电系统、太阳能光热 发电的蓄热传热系统。
制备本发明纳米熔盐所用的装置如下：
该装置包括移动式电伴热 （10)， 太阳能集热系统 （9)、 带夹层 （13) 的熔盐罐 （2)， 气 流粉碎干燥器（3)， 热空气产生器（4)， 造粒装置（5)， 冷却装置 （20)， 搅拌装置（11)， 进 料口 ( 12)；
所述熔盐罐（2)， 气流粉碎干燥器（3)， 造粒装置（5)， 冷却装置（20)通过管道依次串 联；所述热空气产生器（4)通过管道与所述气流粉碎干燥器（3)串联；所述移动式电伴热（10) 和所述太阳能集热系统 （9) 分别通过管道与所述夹层 （13) 相串联； 移动式电伴热 （10) 或 太阳能集热系统 (9)加热热载体进而加热熔盐罐 （2) 来制备高温熔盐， 所制备的高温熔盐通过 管道从气流粉碎干燥器 （3) 上端流进， 而热空气产生器 (4)产生的热空气则从气流粉碎干燥器 (3) 的下端流进， 从而达到干燥、 粉碎高温熔盐的目的， 经干燥后的高温熔盐置于造粒装置 (5) 中进行造粒， 再在冷却装置 （20) 中冷却即得高温熔盐。
所述搅拌装置 （11 ) 设于所述熔盐罐 （2) 内， 该搅拌装置 （11) 为机械搅拌装置， 用于 大规模制备熔盐过程中的搅拌混匀， 所述进料口 （12) 设于所述熔盐罐 （2) 上顶部， 以便于 从上方加入熔盐的各原料组成成分。
所述太阳能集热系统 （9) 上还引出另一管道与夹层 （13)相串连， 该管道上设有高温储 存罐（1)。 所述太阳能集热系统（9)与所述高温储存罐（1 )之间设有阀门， 用于控制太阳能 集热系统 9中的热载体向高温储存罐（1)中流动与否； 当关闭太阳能集热系统（9)与高温储 存罐（1)之间的阀门时， 可以使用太阳能集热系统（9)或是移动式电伴热 （10)直接加热热 载体进而加热熔盐罐 （2) 的方式来制备高温熔盐； 当能源充足或熔盐罐 （2) 不需要加热时， 可打开太阳能集热系统 （9) 与高温储存罐 （1 )之间的阀门， 经过太阳能集热系统 （9) 加热 的热载体便可通过管道流向高温储存罐（1 )进而储存起来， 当需要加热时， 可以通过泵（19) 抽进夹层 （13) 进而加热熔盐罐 （2) 来制备高温熔盐。
所述热空气产生器（4)为热交换器， 所述夹层（13)、所述热交换器以及所述气流粉碎干 燥器 （3) 通过管道依次串联， 所述热交换器还与一鼓风机 （15) 相连。 当高温熔盐制备完毕 后， 夹层（13)中的热载体通过管道流向热交换器进而用于加热用鼓风机（15)鼓进热交换器 的空气， 该被加热后的空气通过管道从气流粉碎干燥器 （3) 的下方流入用于干燥从其上方流 进的高温熔盐， 从而实现夹层 （13) 内的热载体的余热再利用， 节能环保。
该装置还包括低温储存罐（18)， 所述热交换器与所述低温储存罐（18)通过管道相串联， 所述低温储存罐 （18) 另一端通过管道引出一泵 III ( 17)， 所述泵 III ( 17) 引出两管道分别与 所述太阳能集热系统 （9) 以及所述移动式电伴热 （10) 相串连； 所述泵 III ( 17) 与所述太阳 能集热系统 （9) 以及所述泵 ΙΠ ( 17) 与所述移动式电伴热 （10) 之间分别设有陶门， 用于控 制所述低温储存罐 （18) 中的热载体的流向。 从夹层 （13)流出的热载体加热过鼓风机 （15) 鼓出来的空气后通过管道流向低温储存罐 （18)， 而低温储存罐 （18) 出来的热载体则可通过 分为两路的管道， 流向移动式电伴热 （10)， 经过其加热进而用于加热制备高温熔盐的熔盐罐 来制备高温熔盐； 或是流向太阳集热系统能 （9)， 该流向太阳能集热系统 （9) 的热载体或储 存于高温储存罐以便后续用于加热制备高温熔盐，或是直接用于加热制备高温熔盐。该段设计 实现了热载体的循环利用， 降低成本， 节能环保。
该装置还包括料仓 （6)、 包装装置 （7)和存储装置 （8); 所述料仓 （6)、 包装装置 （7) 通过管道串联， 所述包装装置 （7) 与存储装置 （8)相串联； 将上述经造粒装置 （5)造粒后 的熔盐冷却后暂时存放于料仓 （6)， 然后再使用包装装置 （7)进行包装， 最后使用储存装置 (8) 储存备用。
所述熔盐罐 （2) 与所述气流粉碎干燥器 （3) 之间设有泵 I ( 14), 所述热交换器与所述 低温储存罐（18)之间设有泵 II ( 16)； 所述高温储存罐（1)与所述热夹层（13)之间设有泵 IV ( 19)； 泵 I ( 14)用于将熔盐罐 （2) 中制备的熔盐通过管道从气流粉碎干燥器 （3) 的上 方抽进； 泵 II ( 16)用于将热交换器出来的热载体通过管道抽进低温储存罐（18); 泵 IV ( 19) 用于将高温储存罐（1) 中的高温热载体通过管道抽进夹层（13)进而加热熔盐罐（2)制备熔 。
所述太阳能集热系统（9)采用槽式、塔式、碟式或线性菲涅尔式的太阳能光热发电方式。 从成本和技术成熟度的角度优选槽式和塔式，当选用光热发电的槽式镜场作为聚集太阳能的方 式，通过集热管中的高温热载体直接加热熔盐罐。目前常见的高温热载体是高温熔盐、导热油、 过热水蒸气， 在槽式镜场中优选导热油。 当选用光热发电的塔式镜场作为聚集太阳能的方式， 通过吸热器中的高温热载体直接加热熔盐罐。 目前常见的高温热载体是高温熔盐、导热油、过 热水蒸气， 在塔式镜场中优选熔盐。
所述熔盐罐（2)与所述泵 I ( 14)之间设有阀门， 该阔门用于控制熔盐罐（2) 中的高温 熔盐是否通过管道流向气流粉碎干燥器 （3); 所述热交换器与所述夹层 （13)之间设有阀门， 该陶门用于控制夹层 （13) 中的热载体是否通过管道流向热交换器。。
所述热载体为高温熔盐、 导热油、 过热水蒸气。
该装置设计有两个加热系统， 分别为太阳能集热系统 (9)和移动式电伴热 (10)， 当阳光充足 时， 可以使用太阳能集热系统 (9)， 得到的高温热载体可部分直接加热熔盐罐， 另外部分可直 接存储起来， 满足太阳能不足时对热载体的需求。 另外， 当太阳辐射不足时， 还可以使用移动 式电伴热 (10)，保证设备在太阳辐射不足时使用， 该制备装置充分利用了自然能源，节能环保。 本发明制备方法可根据具体情况选用加热方式可选择移动式电伴热或太阳能集热。如果是 在用料现场， 比如太阳能光热电站， 可直接使用聚集的太阳能， 环保节能。 另外， 该方法还充 分利用熔盐罐夹层内热载体的余热， 使其通过热交换装置加热所需的热空气。另外， 待热交换 装置内的热载体加热完空气，可通过管道流入低温储能管进而流向太阳能集热系统换移动式电 伴热，进而被加热，进而用于加热熔盐罐来制备高温碳酸纳米熔盐，实现了热载体的循环利用， 降低成本，节能环保。本发明方法中得到的液相熔盐混合体系在经过气流粉碎干燥器后直接形 成干燥均匀的粉末状， 一方面便于包装出售。 另外一方面是使用时性能均一稳定。
附图说明
图 1本发明方法所用装置的结构示意图；
附图标记列示如下： 1-高温储存罐， 2-熔盐罐， 3-气流粉碎干燥器， 4一热空气产生器， 5- 造粒装置， 6-料仓， 7-包装装置， 8-存储装置， 9-太阳能集热系统， 10-移动式电伴热， 11-搅拌 装置， 12-进料口， 13-夹层， 14-泵 I , 15-鼓风机， 16-泵 II , 17-泵 III, 18-低温储存罐， 19-泵 IV, 20-冷却装置。
具体实施方式
为使本发明的目的、技术方案和优点更加清楚， 下面将结合本发明实施例中的附图， 对本 发明实施例中的技术方案进行清楚、完整地描述， 显然， 所描述的实施例是本发明一部分实施 例， 而不是全部的实施例。基于本发明中的实施例， 本领域普通技术人员在没有作出创造性劳 动前提下所获得的所有其他实施例， 都属于本发明保护的范围。
实施例中未注明具体实验步骤或条件者，按照本领域内的文献所描述的常规实验步骤的操 作或条件即可进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规试剂产 品。
本发明实施例中所使用设备和试剂的来源：
碳酸钾、 碳酸钠、 碳酸锂、 氯化钠、 硝酸钾、 硝酸钠、 亚硝酸钠、 硝酸铯、 二氧化硅、 氧 化锌、 三氧化二铝、 二氧化钛、 氧化镁、 氧化钙等都是工业纯级， 商购途径获得， 一般化学用 品公司可以购买到。
本发明中的纳米粒子可以是商购途径获得也可以是自行制备， 只要所选 Si02纳米粒子、 ZnO纳米粒子、 A1203纳米粒子、 Ti02纳米粒子、 MgO纳米粒子、 CaO纳米粒子的平均粒径 在 10〜30nm范围内， 就能实现本发明的发明目的。
另外，纳米粒子的制备可采用气相法也可采用物理法和化学法制备的纳米粒子以及商购的 都可以实现本发明的发明目的， 只要所选纳米粒子的粒径在 10〜30nm范围内即可。
本发明硝酸纳米熔盐传热蓄热介质的制备方法如下： 1 ) 按比例组成熔盐体系， 并从加料口加入熔盐罐， 打开夹层与太阳能集热系统之间的阀 门使经太阳能集热系统加热的热载体流向夹层静态加热到熔盐罐内的熔盐体系除气除水使其 成熔融状态， 加热温度为熔盐相变温度以上 50〜100°C左右， 保温 10〜30min;
2)将纳米粒子按比例加入到上述熔盐罐， 机械搅拌熔融混合物 0.5〜lh， 以使其初步混合 均勾， 再搅拌保温 0.5〜lh， 使其充分混合均匀， 得到高温熔融盐；
3 ) 打开熔盐罐的出料口将步骤 2)熔盐用熔盐泵泵入气流粉碎干燥器， 同时将熔盐罐中 的高温热载体通过热交换装置加热空气得所需的热空气，然后使该热空气自气流粉碎干燥塔的 底部流入气流粉碎干燥器， 造粒、 冷却得均匀稳定的纳米熔盐传热蓄热介质。
4)将步骤 3 )所得纳米熔盐传热蓄热介质放入料仓， 分装， 保存。
需要说明的是：本实施例所用的装置为发明人自行研发的装置，该装置配有两套加热装置， 包括移动式电伴热和太阳能集热， 在生产过程中， 可根据具体情况选择加热方式。熔盐罐夹层 中的热载体可以是高温导热油或熔盐或过热水蒸气； 当这些热载体加热完熔盐罐内的熔盐后， 充分利用其余热， 使其流到热交换器来加热热空气。
注意： 实施例 1〜4都按照上述制备方法而得。
实施例 1.基于 KNC -NaNCh二元硝酸盐体系的纳米熔盐的性能比较
1 )熔点测试：
采用通用的差示扫描仪 DSC进行 （常压下扫描）。
2) 热稳定性测试
对制备得到二元硝酸纳米熔盐及对照（每种二元硝酸纳米熔盐的原二元硝酸熔盐）进行热 稳定性测试。
测试采用重量法进行：将需测试的熔盐样品加入到不同的镍制坩埚中，放入温控炉进行加 热， 用分析天平称重， 从常温开始进行实验， 然后静态加热到固体全部熔融， 每个一段时间自 然冷却到室温取出实验坩埚， 用分析天平进行称重。如果在某一温度段内， 样品的重量不再减 少， 则提高温控炉的温度。然后每隔一段时间取出实验坩埚用分析天平进行称重， 直到另一个 稳定态之后再继续升温。如此循环， 记录下特定保温温度和保温时间， 并计算出特定保温温度 和保温时间所对应的损失率和剩余率。
实验结果：
本实施例所配制并复合而得的二元硝酸纳米熔盐及其配方如表 1所示
表 1.实施例 1制备得到的二元硝酸纳米熔盐
二元硝酸纳 KN03-NaN03熔盐体系重 t百 纳 米 粒 子 种 类 及 其 占 米熔盐编号 分比配比 （同时也是对照） KN03-NaN03熔盐体系重邐 ：的
Figure imgf000011_0001
1 ) 的熔点测试结果显示， 如表 2所示， 与相应的对照相比， No.ll~15号产品的熔点有所 降低， 但是不明显。
但是随着加入的纳米粒子的比例增加， 与相应的对照相比， 熔点降低程度更明显， 幅度有 所提高。
表 2.熔点测试结果
二元硝酸纳米熔盐编号 熔点 °c
对照:硝酸钾 10 % ; 硝酸钠 90% 270
(相变潜热大， 熔点太高）
No.l 252
No.2 250
No.3 251
No.4 254
No.5 251
对照:硝酸钾 60 %； 硝酸钠 40 % 210
(特点： 熔点低， 相变潜热小） Νο.6 201
No.7 202
No.8 200
No.9 198
No.10 199
对照:硝酸钾 40 % ; 硝酸钠 60% (相变 220
潜热大， 熔点适中， 硝酸钠成本低于硝
酸钾， 所以该体系被国际通用， 称为
solar salt)
No.11 216
No.12 217
No.13 216
No.14 218
No.15 216 ) 热稳定性测试， 具体结果见表 3
表 3.565°C下的损失率统计结果
时间 （小时） 30 100 二元硝酸纳米熔盐编号
对照： 硝酸钾 10 % ; 硝酸钠 90% 4% 10%
No.l 2.9% 8%
No.2 2.5% 7.5%
No.3 2.3% 7.1%
No.4 2.1% 7%
No.5 2.4% 7.4% 对照:硝酸钾 60 %； 硝酸钠 40 % 3% 9%
No.6 1.9% 6.5%
No.7 2% 6.0%
No.8 1.9% 6.4%
No.9 1.9% 6.2% Νο.10 2% 6.1%
对照:硝酸钾 40 %； 硝酸钠 60 % 2.5% 8.5%
No.11 1.0% 5%
No.12 1.2% 5.5%
No.13 1.2% 5.2%
No.14 1.0% 4.9%
No.15 1.3% 5.3%
可以看出在 565°C度下， 加入金属氧化物纳米粒子能够使各组产品的热稳定性相对于对照 明显提高。
表 4.660°C下的损失率统计结果
Figure imgf000013_0001
可以看出在 660°C度下， 各组产品的热稳定性相对于对照明显提高。
实施例 2.基于 KNOvNaNC 二元硝酸盐体系的纳米熔盐的性能比较
1 )熔点测试：
采用通用的差示扫描仪 DSC进行 （常压下扫描）。
2) 热稳定性测试
对制备得到二元硝酸纳米熔盐及对照（每种二元硝酸纳米熔盐的原二元硝酸熔盐）进行热 稳定性测试。
测试采用重量法进行 （方法同实施例 1 ):
实验结果：
该实施例所配制并复合而得的二元硝酸纳米熔盐及其配方如表 5所示
表 5.实施例 2制备得到的二元硝酸纳米熔盐
Figure imgf000014_0001
1 )熔点测试结果显示， 如表 6所示， 与相应的对照相比， Νο.16~30号产品的熔点有所降 低但是不显著
Figure imgf000015_0001
BjfB] (小时） 30 100 二元硝酸纳米熔盐^^ - 对照： 硝酸钾 30% 亚硝酸钠 70 % 4% 9.5%
No.16 2.7% 7.5%
No.17 2.4% 7.2%
No.18 2.5% 7.1%
No.19 2.3% 7%
No.20 2.2% 7.% 对照： 硝酸钾 60% 亚硝酸钠 40% 3.5% 9%
No.21 2.0% 6.8%
No.22 2.1% 6.5%
No.23 1.9% 6.%
No.24 2.1% 6.0%
No.25 1.9% 6.0%
对照： 硝酸钾 55 % 亚硝酸钠 45 % 2.8% 8%
No.26 1.5% 5.5%
No.27 1.3% 5.0%
No.28 1.2% 5.0%
No.29 1.3% 4.5%
No.30 1.4% 5.0% 可以看出在 500°C度下， 加入金属氧化物纳米粒子能够使各组产品的热稳定性相对于对照 明显提高。
表 8.60CTC下的损失率统计结果
Figure imgf000016_0001
Νο.26 3.5% 10%
No.27 3.2% 8%
No.28 3.5% 9%
No.29 2.5% 8%
No.30 2.5% 8.5%
可以看出在 600°C度下， 各组产品的热稳定性相对于对照明显提高。
实施例 3.三元硝酸纳米熔盐传热蓄热介质的制备方法
表 9为按照该实施例的各组三元硝酸纳米熔盐的配方以及配方中纳米粒子的粒径，以及根 据现有技术在三元硝酸熔盐中加入第四种成分所得的硝酸熔盐的配方 （XI )和四元硝酸熔盐 的配方 （X2)
其中， 申请号为 200710027954.1 的中国发明专利公开一种熔融盐传热蓄热介质及其制备 方法， XI为该专利发明人根据其说明书实施例 1所记载的配方和制备方法所得的带添加剂的 硝酸熔盐；
申请号为 00111406.9 的中国发明专利公开了一禾中 (LiN03-KN03-NaN03-NaN02)混合熔盐 及制备方法， X2为该专利发明人根据其申请文件所记载的的配方和制备方法所得的四元硝酸 熔盐。
表 9.实施例 3的三元硝酸纳米熔盐配方及对应纳米粒子的粒径 三元硝酸纳 三元硝酸熔盐重量份配 纳米粒子种类及重量份配比/ kg 裸纳米粒平 米熔盐编号 比/ kg 均粒径 /
No. l 硝酸钾 60、 硝酸钠 8、 亚 Si02l、 MgO 1 10
No.2 硝酸钠 10 Zn0 3 22
No.3 A1203 4 12
No.4 硝酸钾 20、 硝酸钠 20、 Ti02 1.5 18
No.5 亚硝酸钠 50 MgO 1.2、 ZnO 1、 TiO20.4、 A1203 1.6、 30
Figure imgf000017_0001
No.6 硝酸钾 25、 硝酸钠 15、 Si02 1.3、 ZnO 0.7、 CaO 1 20
No.7 亚硝酸钠 40 Si02 1.5、 ZnO 0.5、 14
Figure imgf000017_0002
No.8 硝酸钾 53、 硝酸钠 7、 亚 Al2O3 0.7、 MgO 0.3 19
No.9 硝酸钠 40 TiO2 1.0、 Mg O 0.2、 AI2O3 0.8 23
No.10 MgO 2.0、 CaO 0.5 16 No.ll 硝酸钾 45、 硝酸钠 14、 Si02 1.5、 AI2O3 1.5 13
No.12 亚硝酸钠 40 ZnO 1.3、 Ti021.7 17
No.13 AI2O3I.2, Ti021.8 15
No.14 ZnO 1、 Ti02 l、 MgO 1 20
No.15 ZnO 1.0、 TiO20.3、 Al2O3 0.6、 S1O2 I.I 27
No.16 硝酸钾 30、 硝酸钠 15、 Ti02 1.3、 Si022.7 11
No.17 亚硝酸钠 40 MgO 1.2、 ZnO 1.8、 A1203 1.0 15
No.18 MgO 2.1、 ZnO 1.9 28
No.19 MgO 1.4、 ZnO 0.6、 A1203 1.1、 SiO20.9 14
No.20 硝酸钾 35、 硝酸钠 12、 Si02 4 16
No.21 亚硝酸钠 22 ZnO 2.3 AI2O3 1.7 23
No.22 MgO 3.4、 ΉΟ2 Ο.6 25
No.23 硝酸钾 47、 硝酸钠 13、 MgO 0.4、 ZnO 0.7、 Ti02 l.l、 Si02 1.8 24
No.24 亚硝酸钠 30 MgO 0.9、 AI2O3 O.2, Si022.9 12
No.25 MgO 0.3、 ZnO 2.4、 Si02 1.4、 CaO 0.5 20
XI 硝酸钾 52.2%、 硝酸钠 0
6.9%、 亚硝酸 39.6% 添
加剂硝酸铯 0.3%、 氯化
钾 1%
X2 硝酸锂 1%、硝酸钾 79%、 0
硝酸钠 10%、 亚硝酸钠
10%
性能测试. XI， X2以及本发明实施例 3的 No.1-25所制备而得的三元硝酸纳米熔盐性能测
( 1 ) 热稳定性测试：
测试采用重量法进行 （方法同实施例 1 ): 分别采用该方法对 XI、 X2和本发明实施例 3 的三元硝酸纳米熔盐组 No.l〜25进行测试， 根据测试数据得表 10。
表 10.三元硝酸纳米熔盐热稳定性测试数据
三元硝酸纳 剩余率％ 剩余率％ 剩余率％ 剩余率％ 米熔盐编号 120 °C， 保温 10h 550 °C , 保温 20h 570 °C， 保温 35h 600 °C， 保温 46h
XI ― 96 86 70 X2 -- 97 84 69
No. l 95 83 68
No.2 -- 96 87 67
No.3 -- 98 86 65
No.4 -- 94 85 63
No.5 -- 97 82 68
No.6 -- 98 90 80
No.7 -- 99 88 77
No.8 -- 98 89 79
No.9 -- 99 87 78
No.10 -- 98 89 79
No. ll 100 100 100 98
No.12 100 100 100 97
No.13 100 100 100 97
No.14 100 100 100 99
No.15 100 100 100 98
No.16 100 100 100 99
No.17 100 100 100 98
No.18 100 100 100 98
No.19 100 100 100 97
No.20 100 100 100 100
No.21 100 100 100 99
No.22 100 100 100 100
No.23 100 100 100 100
No.24 100 100 100 99
No.25 100 100 100 98
注： 上表中 --代表该传热蓄热介质为固态， 无法测其剩余率
由表 10可以看出： XI、 X2熔盐以及三元硝酸纳米熔盐组 Νο.1〜Νο.10的传热蓄热介质 在 120 °C都成固体状态， 不能测出其剩余率。而当温度升到 550 °C时， 其基本可以稳定的运行， 但在 570 °C下出现明显的由于分解造成的组分流失，其中 XI剩余率为 86%，X2剩余率为 84%， 相比来说，本发明实施例 3的三元硝酸纳米熔盐组 Νο.1〜Νο.10三元硝酸纳米熔盐传热蓄热介 质因分解而造成的组分流失相对较少； 而当运行 46个小时， 保温温度为 600°C时， XI、 X2组 分损失率分别达 30%、 31%, 本发明实施例 3的三元硝酸纳米熔盐组 Νο.1〜Νο.10三元硝酸纳 米熔盐传热蓄热介质组分流失也随着增加。
相比之下， 本发明实施例 3的三元硝酸纳米熔盐组 Νο.10〜Νο.25制备的三元硝酸纳米熔 盐传热蓄热介质各个实验温度下， 组分流失明显减少， 其在 120-600°C基本都能稳定的运行。 其中三元硝酸纳米熔盐组 Νο.10〜Νο.25的传热蓄热介质在 120-600°C基本没有组分流失。从上 述数据可以看出， 本发明实施例 3的三元硝酸纳米熔盐组 Νο.10〜Νο.25工艺条件以及本发明 实施例 3 的配方的三元硝酸熔盐中加入特定粒径以及特定用量的纳米粒子能够有效改善熔盐 传热蓄热介质在 600°C下的稳定性。
(2)最低熔化温度、 相变潜热测试：
采用通用的差示扫描仪 （简称 DSC) 对样品熔盐进行最低熔化温度， 相变潜热测试。 测 试结果如表 3。
结果显示，本发明实施例 3的三元硝酸纳米熔盐组 No.l〜No.25制备的三元硝酸纳米熔盐 的最低熔化温度和相变潜热与现有技术 XI和 X2的熔盐体系相比最低熔化温度降低， 相变潜 热提高，因此才能保持本发明实施例 3的三元硝酸纳米熔盐传热蓄热介质低的下限使用温度的 同时，提高其安全上限使用温度，使本发明实施例 3的三元硝酸纳米熔盐传热蓄热介质使用温 度变宽。
( 3)与三元硝酸熔盐相比，本发明实施例 3的三元硝酸纳米熔盐组 No.l〜No.25制备的三 元硝酸纳米熔盐传热蓄热介质的相变体积收縮率减少， 导热率提高。 本发明实施例 3 的 No.l-No.25制备的三元硝酸纳米熔盐传热蓄热介质的相变体积收縮率减少的具体数据见表 11。
性能测试方法和步骤采用上述方法和步骤， 测试结果如表 11， 其中相变潜热提高百分比 和体积收縮减少百分比分别是跟普通三元硝酸熔盐 KN03-NaN03-NaN02相比的， 定义普通三 元硝酸熔盐 KN03-NaN03-NaN02的相变潜热和体积收缩相对值为 1时， 本发明实施例 3的三 元硝酸纳米熔盐组 No.l〜No.25制备的三元硝酸纳米熔盐传热蓄热介质以及 XI、 X2硝酸熔盐 传热蓄热介质的相应相变潜热增加和体积收缩减少百分比的值。 表 11.本发明实施例 3的三元硝酸纳米熔盐组 No.l-No.25以及 XI和 X2性能测试指标 编号 最低熔化温度 °c 相变潜热提高百分比 体积收缩减少百分比
XI 145 0.04 0.03
X2 148 0.06 0.02
No.l 135 0.16 0.11 No.2 132 0.16 0.13
No.3 130 0.14 0.12
No.4 131 0.15 0.14
No.5 133 0.18 0.12
No.6 125 0.15 0.14
No.7 128 0.17 0.13
No.8 125 0.15 0.16
No.9 127 0.16 0.15
No.10 128 0.14 0.15
No.ll 113 0.17 0.10
No.12 119 0.16 0.12
No.13 118 0.15 0.16
No.14 116 0.18 0.14
No.15 118 0.15 0.14
No.16 119 0.16 0.12
No.17 112 0.17 0.13
No.18 113 0.18 0.12
No.19 116 0.16 0.14
No.20 115 0.18 0.13
No.21 111 0.19 0.14
No.22 110 0.18 0.15
No.23 111 0.17 0.17
No.24 116 0.18 0.15
No.25 118 0.19 0.16 由表 11可以看出： 与 XI、 X2熔盐传热蓄热介质相比， 本发明各的三元硝酸纳米熔盐传 热蓄热介质基本都维持在低最低熔化温度，保证本发明实施例 3的三元硝酸纳米熔盐传热蓄热 介质低的使用温度。 同时与 XI、 X2熔盐传热蓄热介质相比， 本发明各实施例的三元硝酸纳米 熔盐传热蓄热介质的相变潜热都有所提高， 体积收縮比都有所减少。说明： 本发明通过在三元 硝酸熔盐的体系中加入纳米粒子， 限制了熔盐材料相变时的体积收缩， 降低了三元硝酸纳米熔 盐传热蓄热介质的体积收缩比， 提高了本发明三元硝酸纳米熔盐传热蓄热介质的导热率。 通过仔细对比表 11数据可以看出， 本发明实施例 3的三元硝酸纳米熔盐组 No. ll〜No.25 的的传热蓄热介质的最低熔化温度更低，相变潜热提高和体积收缩比减少的数值更多。总体来 说， 本发明实施例 3的三元硝酸纳米熔盐 No. l l〜No.25的传热蓄热介质各项性能指标更优。 实施例 4.多元硝酸纳米熔盐的制备步骤
下表 12的配比为实施例 4的一系列多元硝酸纳米熔盐。表 12为本实施例不同编号的多元 硝酸纳米熔盐的配方以及配方中纳米粒子的粒径。
表 12.多元硝酸纳米熔盐配方
多元硝酸纳 多元硝酸熔盐质 纳米粒子种类及其占多元熔盐体系 纳米粒子 米熔盐编号 量百分比含量 /% 总质量的百分比 /% 的粒径 /nm
No. l 硝酸钾 20、硝酸钠 Si02 1 10 nm
No.2 20、 亚硝酸钠 50 ZnO 1 10 nm
No.3 和硝酸铯 10
A1203 1 10 nm
No.4 Ti02 1 10 nm
No.5 MgO 1 10 nm
No.6 硝酸钾 60、硝酸钠 Si02 5 30nm
No.7 10、 亚硝酸钠 25 CaO 5 30nm
No.8 和硝酸铯 5
A1203 5 30nm
No.9 Ti02 5 30nm
No.10 MgO 5 30nm
No. l l 硝酸钾 60、硝酸钠 Si02 3 20nm
20
No.12 、 亚硝酸钠 10
ZnO 3 20nm
和硝酸铯 10
No.13 A1203 3 20nm
No.14 Ti02 3 20nm
No.15 MgO 3 20nm
No.16 硝酸钾 40、硝酸钠 Si02 3 20nm
No.17 15、 亚硝酸钠 38 ZnO 3 20nm
No.18 和硝酸铯 7
A1203 3 20nm
No.19 Ti02 3 20nm
No.20 MgO 3 20nm Νο.21 硝酸钾 40、硝酸钠 Si021.5、 ZnO 1.5 CaO 0.5 20nm
No.22 15、 亚硝酸钠 38 Si02l、 Zn0 1、 A1203 1 20nm
No.23 和硝酸铯 Ί Si02l、 Zn0 1、 AI2O3 0.5 > TiO20.5 20nm
No.24 SiO20.6、 ZnO 0.6 A1203 0.6、 Ti02 20nm
0.6、 MgO 0.6
No.25 ZnO 1、 AI2O3 1、 TiO20.5、 MgO 0.5 20nm
对制备获得的多元硝酸纳米熔盐进行性能测试如下：
1、 热稳定性测试 （测试方法歩骤同实施例 3 ) -XI、 X2同实施例 3:
分别采用上述方法对表 12所示的多元硝酸纳米熔盐及对照 XI和对照 X2进行热稳定性测 试， 测试结果如表 13所示。
表 13.多元硝酸纳米熔盐热稳定性测试数据
Figure imgf000023_0001
由表 13可看出， 对照 XI的稳定温度界限为 550°C， 550°C下保温 30小时， 损失率约 4%， 保温 50小时时损失率为约 14%; 对照 X2的稳定温度界限为 550°C， 550°C下保温 30小时，损 失率约 3%， 保温 50小时时损失率为约 16%; 而本发明制备的多元硝酸纳米熔盐 No.l- No.25 在 600°C的损失率与对照在 550°C的损失率相当， 此结果说明， 本发明的产品具有更好的热稳 定性， 能够在 600°C下稳定操作较长时间。
2、 最低熔化温度、 相变潜热测试：
采用通用的差示扫描仪 （简称 DSC) 对样品熔盐进行最低熔化温度， 相变潜热测试。 测 试结果如表 14。
结果显示， 本发明制备的多元硝酸纳米熔盐 No.l- No.25的最低熔化温度和相变潜热与现 有技术 XI和 X2的熔盐体系相比最低熔化温度降低， 相变潜热提高， 因此才能保持本发明多 元硝酸纳米熔盐传热蓄热介质低的下限使用温度的同时，提高其安全上限使用温度，使本发明 多元硝酸纳米熔盐传热蓄热介质使用温度变宽。
3、 相变体积收縮率测试：
与对照 XI、 X2硝酸熔盐相比， 本发明制备的多元硝酸纳米熔盐 No.l-No.25传热蓄热介 质的相变体积收缩率减少， 导热率提高。 本发明制备的多元硝酸纳米熔盐 No.l- No.25传热蓄 热介质的相变体积收缩率减少的具体数据见表 14。
性能测试方法和步骤采用上述方法和步骤， 测试结果如表 14， 其中相变潜热提高百分比 和体积收縮减少百分比分别是跟普通三元硝酸熔盐 KN03-NaN03-NaN02相比的， 定义普通三 元硝酸熔盐 KN03-NaN03-NaN02的相变潜热和体积收缩相对值为 1时， 本发明制备的多元硝 酸纳米熔盐 No.l- No.25传热蓄热介质以及 XI、 X2硝酸熔盐传热蓄热介质的相应相变潜热增 加和体积收缩减少百分比的值。
表 14.熔盐熔点测试数据
Figure imgf000024_0001
由表 14看出： 与 XI、 X2熔盐传热蓄热介质相比， 本发明制备得到的多元硝酸纳米熔盐 传热蓄热介质基本都维持在较低熔化温度，保证本发明多元硝酸纳米熔盐传热蓄热介质低的使 用温度。 同时与 XI、 X2熔盐传热蓄热介质相比， 本发明制备得到的多元硝酸纳米熔盐传热蓄 热介质的相变潜热都有所提高， 体积收縮比都有所减少。说明： 本发明通过在多元硝酸熔盐的 体系中加入纳米粒子， 限制了熔盐材料相变时的体积收缩， 降低了多元硝酸纳米熔盐传热蓄热 介质的体积收缩比， 提高了本发明多元硝酸纳米熔盐传热蓄热介质的导热率。
通过仔细对比表 14可以看出， 本发明制备得到的多元硝酸纳米熔盐 No.16- No.25传热蓄 热介质的最低熔化温度更低， 相变潜热提高和体积收縮比减少的数值更多。总体来说， 本发明 制备得到的多元硝酸纳米熔盐 No.16- No.25传热蓄热介质各项性能指标更优。
实施例 5.碳酸纳米熔盐传热蓄热介质的制备方法 1 )釆用气相法制备金属氧化物纳米粒子 MgO和 /或非金属氧化物纳米粒子 Si02 (注意本 步骤中的纳米粒子可以采用商购途径获得，商购所得的纳米粒子同样能够实现本发明的发明目 的）；
2) 将氯化钠和碳酸锂混合均匀并从加料口加入熔盐罐， 打开夹层与太阳能集热系统之间 的阔门使经太阳能集热系统加热的热载体流向夹层静态加热到熔盐罐内的固体全部熔融，保温 10〜30min自然冷却到室温并机械粉碎；
然后将碳酸钾和碳酸钠加入到熔盐罐， 搅拌使混合均匀， 得碳酸熔盐体系， 再使用经太阳 能集热系统加热的热载体静态加热熔盐罐除气除水使其成熔融状态，加热温度为熔盐相变温度 以上 50〜100°C左右， 保温 10〜30min;
3 )将步骤 1 )所得纳米粒子加入到上述熔盐罐， 机械搅拌熔融混合物 0.5〜lh， 以使其初 步混合均匀， 保温再搅拌 0.5〜lh， 使其充分混合均匀， 得到高温熔融盐；
4) 打开熔盐罐的出料口将步骤 3 )碳酸熔盐用熔盐泵泵入气流粉碎干燥器， 同时将熔盐 罐中的高温导热油通过热交换装置加热空气得所需的热空气，然后使该热空气自气流粉碎干燥 塔的底部流入气流粉碎干燥器， 造粒得均匀稳定的碳酸纳米熔盐传热蓄热介质。
5 )将步骤 4)所得碳酸纳米熔盐传热蓄热介质放入料仓， 分装， 保存。
需要说明的是：本实施例所用的装置为发明人自行研发的装置，该装置配有两套加热装置， 包括移动式电伴热和太阳能集热， 在生产过程中， 可根据具体情况选择加热方式。熔盐罐夹层 中的热载体可以是高温导热油或熔盐或过热水蒸气； 当这些热载体加热完熔盐罐内的熔盐后， 充分利用其余热， 使其流到热交换器来加热热空气。
表 15为按照实施例 5的制备方法而得的碳酸纳米熔盐的各配方以及配方中纳米粒子的粒 径， 以及根据现有技术在碳酸熔盐的配方 （X3)其中， 申请号为 200910037348.7的中国发明 专利公开一种含锂碳酸熔融盐传热蓄热介质及其制备方法， X3为该发明发明人根据其说明书 实施例 4所记载的配方和制备方法所得的含锂的碳酸熔盐 （没含有纳米粒子）；
表 15.实施例 5制备得到的碳酸纳米熔盐配方及对应纳米粒子的粒径 碳酸纳米 碳酸熔盐重量份配 纳米粒子种类及重量份配比/ kg 纳米粒子平均 熔盐编号 比/ kg 粒径 /nm
No.l 碳酸钾 39、 碳酸钠 Si02l ; MgO 1 10
No.2 46、碳酸锂 14.7、氯 Zn0 3: CaO l 22
No.3 化钠 0.3 Al2034 12
No.4 碳酸钾 30、 碳酸钠 Ti02 1.5 18
No.5 50、 碳酸锂 30、 氯 MgO 1.2； ZnO 1； Ti02 0.4； A1203 1.6； Si02 30 化钠 10 0.8； CaO l
Νο.6 碳酸钾 60、 碳酸钠 Si02 1.3； ZnO 0.7 20
No.7 20、 碳酸锂 10、 氯 Si02 1.5; ZnO 0.5; A1203 2.0； CaO 0.5 14
化钠 5
No.8 碳酸钾 35、 碳酸钠 A1203 0.7； MgO 0.3 19
No.9 35、 碳酸锂 25、 氯 Ti02 1.0； Mg O 0.2； AI2O3 0.8 23
No.10 化钠 9 MgO 2.0; CaO 0.8 16
No.ll 碳酸钾 50、 碳酸钠 S1O2 1.5； AI2O3 1.5 13
No.12 25、 碳酸锂 15、 氯 ZnO l.3; Ti021.7 17
No.13 化钠 7 Al2031.2; ΉΟ2Ι.8; CaO 1.3 15
No.14 ZnO l ; Ti02 1 ; MgO 1 20
No.15 ZnO l.0; TiO2 0.3; A1203 0.6； Si02 1.1 27
No.16 碳酸钾 30、 碳酸钠 Ti02 1.3; S1O2 2.7 11
No.17 20、 碳酸锂 10、 氯 MgO 1.2 ZnO 1.8； AI2O3 1.0 15
No.18 化钠 10 MgO 2.1 ZnO 1.9 ； CaO 1 28
No.19 MgO 1.4 ZnO 0.6； A1203 1.1； Si02 0.9 14
No.20 碳酸钾 35、 碳酸钠 S1O2 4； CaO l 16
No.21 25、 碳酸锂 15、 氯 Zn0 2.3; AI2O3 1.7 23
No.22 化钠 9 MgO 3.4； Ti02 0.6 25
No.23 碳酸钾 40、 碳酸钠 MgO 0.4； ZnO 0.7； Ti02 1.1 ; Si02 1.8 24
No.24 30、碳酸锂 8、氯化 MgO 0.9； AI2O3 0.2； Si02 2.9 12
No.25 钠 3 MgO 0.3； ZnO 2.4； Si02 1.4; CaO 0.7 20
X3 碳酸钾 46%、 碳酸 0
钠 30%、 碳酸锂
20.87%、 氯化钠
3.13%
X3以及本发明碳酸纳米熔盐组 No.l〜25所制备而得的碳酸酸纳米熔盐性能测试
( 1 ) 热稳定性测试 （方法步骤同实施例 3):
分别采用上述方法对 X3和本发明碳酸纳米熔盐组 No.l〜25进行测试，根据测试数据得表 16。
表 16.熔盐热稳定性测试数据
碳酸纳米熔 损失率％ 损失率％ 损失率％ 损失率％
Figure imgf000027_0001
由表 16可看出， 对照 X3在 700 °C及以下温度， 损失率为 0， 当温度升到 816 °C并且保温 40h时损失率为 1%， 而当温度升到 821 °C并且保温 35h时损失率为 7% ; 相比之下， 本发明碳 酸纳米熔盐组在 70CTC及以下温度， 损失率为 0, 当温度升到 816 °C并且保温 40h时损失率为 1 %及以下， 而当温度升到 821 °C并且保温 35h时损失率为 0.8〜1.7%。 很明显， 本发明实施例 的碳酸纳米熔盐组和 X3碳酸熔盐都可以在 800°C温度下稳定运行， 并且相比之下本发明碳酸 纳米熔盐组的熔盐热稳定性更好， 其在 80CTC以上的相应温度的剩余率更大。
( 2) 熔点、 相变潜热测试： 采用通用的差示扫描仪 （简称 DSC )对样品熔盐进行熔点， 相变潜热测试。 测试结果如表 17。 结果显示， 本发明碳酸纳米熔盐组 No. l〜25制备的碳酸纳 米熔盐的熔点和相变潜热与现有技术 X3的熔盐体系相比熔点降低， 相变潜热提高， 因此才能 保持本发碳酸纳米熔盐传热蓄热介质高的上限使用温度的同时， 降低其下限使用温度，使得本 发明碳酸纳米熔盐传热蓄热介质使用温度变宽。
( 3 ) 相变体积收縮率测试： 采用现有技术中常规的测试体积收缩率的方法， 与对照 X3 的碳酸熔盐相比， 本发明碳酸纳米熔盐组 No. l〜25制备的碳酸纳米熔盐传热蓄热介质的相变 体积收缩率减少， 导热率提高。本发明碳酸纳米熔盐组 No.1-25制备的碳酸纳米熔盐传热蓄热 介质的相变体积收縮率减少的具体数据见表 17。
性能测试方法和步骤采用上述方法和步骤， 测试结果如表 17， 其中体积收缩百分比是跟 普通碳酸熔盐 X3相比的， 本发明碳酸纳米熔盐组 No. l〜25制备的碳酸纳米熔盐传热蓄热介 质的相应体积收缩百分比值如下表。
表 17.本发明碳酸纳米熔盐组 No.l〜25以及 X3的性能测试数据 编号 熔点 （°c ) 相变潜热 J/g 体积收缩百分比
X3 392 98 0.2
Νο· 1〜5 262—230 260〜296 0·07〜0· 10
Νο·6〜10 265〜235 250〜288 0·08〜0· 11
Νο· 11〜15 263〜234 256〜291 0.09〜0.10 260〜230 262〜290 0.08-0.09
N oo.21~25 261〜230 263〜300 0·09〜0·11
由表 17可以看出： 与 Χ3熔盐传热蓄热介质相比， 本发明制备得到的碳酸纳米熔盐传热 蓄热介质基本都维持在较低熔点温度， 保证本发明碳酸纳米熔盐传热蓄热介质低的使用温度。 同时与 Χ3熔盐传热蓄热介质相比， 本发明制备得到的碳酸纳米熔盐传热蓄热介质的相变潜热 都有大幅度提高，这可能是由于纳米粒子的加入改变了碳酸熔盐基体的结构而引起的， 同时加 入纳米粒子的本发明碳酸熔盐也限制固液相变时较大的体积收缩，体积收縮比比没有加入纳米 粒子的 Χ3碳酸熔盐减少近 10个百分比。 说明： 本发明通过在普通碳酸熔盐的体系中加入纳 米粒子，限制了熔盐材料相变时的体积收缩，降低了碳酸纳米熔盐传热蓄热介质的体积收缩比， 提高了本发明碳酸纳米熔盐传热蓄热介质的导热率。总体来说，本发明碳酸纳米熔盐组的碳酸 纳米熔盐 Νο.1〜25制备得到的碳酸纳米熔盐传热蓄热介质各项性能指标更优。
本发明实施方式中所列的纳米熔盐传热蓄热介质用作太阳能光热发电的使用方法，可以参 照现有技术中的硝酸熔盐传热蓄热介质用作太阳能光热发电的使用方法。另外，本发明的纳米 熔盐传热蓄热介质还可以在原有的设备的基础上，减少辅助保温设备、措施以及预防熔盐传热 蓄热介质凝固的设备， 降低太阳能光热发电的投资成本。
最后应说明的是： 以上实施例仅用以说明本发明的技术方案， 而非对其限制； 尽管参照前 述实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各 实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换； 而这些修改或者 替换， 并不使相应技术方案的本质脱离本发明各实施例技术方案的精神和范围。

Claims

权利要求书
1.一种纳米熔盐传热蓄热介质，其特征在于：将金属氧化物纳米粒子和 /或非金属氧化物纳 米粒子分散到熔盐体系中复合而得。
2.根据权利要求 1所述的传热蓄热介质，其特征在于：所述纳米粒子为 Si02、 ZnO、 A1203、 Ti02 、 MgO和 /或 CaO纳米粒子， 所述纳米粒子的平均粒径为 10-30nm。
3.根据权利要求 2所述传热蓄热介质， 其特征在于： 所述熔盐体系为硝酸熔盐体系。
4.根据权利要求 3所述传热蓄热介质， 其特征在于： 所述硝酸熔盐体系为二元硝酸熔盐体 系， 所述纳米粒子的重量在所述传热蓄热介质中占 1 % -5 %； 所述二元硝酸熔盐体系为 KN03-NaN03， 其各成分的重量份组成为： 硝酸钾 20-40份； 硝酸钠 60-80份的二元硝酸熔盐 体系 KN03-NaN03;
或所述二元硝酸熔盐体系为 KN03-NaN02， 各成分的重量份组成为： 硝酸钾 30-60份； 亚 硝酸钠 40-70份。
5.根据权利要求 4 所述传热蓄热介质， 其特征在于： 所述二元硝酸熔盐体系为 KN03-NaN03， 所述各成分的重量份组成为： 硝酸钾 40份； 硝酸钠 60份；
或所述二元硝酸熔盐体系为 KN03-NaN02, 各成分的重量份组成为： 硝酸钾 55份； 亚硝 酸钠 45份。
6.根据权利要求 3所述传热蓄热介质， 其特征在于： 所述硝酸熔盐体系为由硝酸钾， 硝酸 钠， 亚硝酸钠形成三元硝酸熔盐体系， 所述传热蓄热介质各组分重量份配比为： 硝酸钾： 20〜 60份; 硝酸钠： 8〜20份; 亚硝酸钠： 10〜50份; 纳米粒子： 1〜5份。
7.权利要求 6所述传热蓄热介质， 其特征在于： 所述传热蓄热介质各组分重量份配比为： 硝酸钾： 30〜45份； 硝酸钠： 12〜15份； 亚硝酸钠： 20〜40份； 纳米粒子： 4〜5份。
8.根据权利要求 3所述传热蓄热介质， 其特征在于： 所述硝酸熔盐体系为主要由硝酸钾、 硝酸钠、亚硝酸钠和硝酸铯组成多元硝酸熔盐体系，所述传热蓄热介质各成分的质量百分比含 量分别为： 硝酸钾 20%-60%， 硝酸钠 10%-20%， 亚硝酸钠 10%-50%， 硝酸铯 5%-10%， 所述 纳米粒子为所述多元硝酸熔盐体系总质量的 1%-5%。
9.根据权利要求 2所述传热蓄热介质， 其特征在于： 所述熔盐体系为由碳酸钾， 碳酸钠， 碳酸锂和氯化钠形成的碳酸熔盐体系。
10.根据权利要求 9所述传热蓄热介质， 其特征在于： 所述传热蓄热介质各组分重量份配 比为： 碳酸钾 30〜60份； 碳酸钠 20〜50份； 碳酸锂 10〜30份； 氯化钠 3〜10份； 纳米粒子： 1〜5份。
11.权利要求 1〜10任一所述的纳米熔盐传热蓄热介质在工业蓄能或太阳能光热发电中的 用途。
12.—种纳米熔盐传热蓄热介质的制备方法， 包括以下步骤：
( 1 ) 将熔盐体系加热使其成熔融状态；
(2) 将纳米粒子按比例加入到熔融的熔盐体系中， 搅拌均匀后保温， 得到高温熔融盐；
( 3) 将所述高温熔融盐冷却， 即得到纳米熔盐传热蓄热介质；
所述纳米粒子为 Si02、 ZnO、 A1203、 Ti02 、 MgO禾 Π/或 CaO纳米粒子， 所述纳米粒子的 平均粒径为 10-30nm;
所述熔盐体系为硝酸熔盐体系或碳酸熔盐体系。
13.根据权利要求 12所述的制备方法， 其特征在于， 使用包括移动式电伴热 （10)， 太阳 能集热系统（9)、 带夹层 （13 ) 的熔盐罐（2)， 气流粉碎干燥器（3)， 热空气产生器（4)， 造 粒装置 （5)， 冷却装置 （20)， 搅拌装置 （11 )， 进料口 （12 ) 的装置；
所述熔盐罐（2)， 气流粉碎干燥器（3 ), 造粒装置（5)， 冷却装置（20)通过管道依次串 联；所述热空气产生器（4)通过管道与所述气流粉碎干燥器（3 )串联；所述移动式电伴热（10) 和所述太阳能集热系统 （9) 相互并联， 并分别通过管道与所述夹层 （13) 串联；
所述搅拌装置 （11 )设于所述熔盐罐（2) 内， 所述进料口 （12 )设于所述熔盐罐 （2)上 顶部。
14.根据权利要求 13所述的方法， 其特征在于， 所述太阳能集热系统 （9) 上还引出另一 管道与夹层 （13)相串连， 该管道上设有高温储存罐 （1 )。
15.根据权利要求 14所述的方法， 其特征在于， 所述热空气产生器 （4) 为热交换器， 所 述夹层（13)、 所述热交换器、 所述气流粉碎干燥器（3 )通过管道依次串联， 所述热交换器还 与一鼓风机 （15)相连。
16.根据权利要求 15所述的方法， 其特征在于， 所述装置还包括低温储存罐 （18)， 所述 热交换器与所述低温储存罐（18)通过管道相串联， 所述低温储存罐（18 )通过管道引出泵 III
( 17)，所述泵 III ( 17 )引出两管道分别与所述太阳能集热系统（9)以及所述移动式电伴热（10) 相串连； 所述泵 ΙΠ ( 17)与所述太阳能集热系统（9)， 以及所述泵 III ( 17 )与所述移动式电伴 热 （10)之间分别设有阀门， 用于控制所述低温储存罐 （18 ) 中的热载体的流向。
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