CN105018035A - Method for integrated packaging preparation of high-temperature composite heat storage material and anti-corrosive coating - Google Patents

Abstract

The invention provides a method for preparing a heat storage material package, which comprises mixing and grinding sodium carbonate and lithium carbonate at a mass ratio of 4:1 to 1:1, and then mixing them with magnesium oxide at a mass ratio of 1:2 to 4 : 1 Mix and grind evenly; add 0.01 to 0.1 gram of sodium silicate solution per gram of graphite and mix evenly to form coating ingredients; spread the coating ingredients on the bottom of the mold and put in a hollow cylinder baffle whose size is smaller than the mold. Add heat storage material to the inner side of the baffle, add coating ingredient system to the outer side of the baffle, pull out the baffle, and add a layer of coating ingredients on it; at a pressure of 5-30kPa, keep the pressure for 0.5min-10min, and press it into a cylindrical shape , Demoulding into a shaped sample, put it into an electric furnace, and sinter it at high temperature after entering an inert atmosphere. The heat storage material packaging package of the present invention has a thermal conductivity increased by more than 30%, a cycle time of more than 16,000 times, and a service life more than three times higher than that of the prior art.

Description

A preparation method for integrated packaging of high-temperature composite heat storage material and anti-corrosion coating

technical field

The invention belongs to the field of energy material science, and in particular relates to a preparation method for an integrated package of a high-temperature composite phase-change heat storage material and an anti-corrosion coating.

Background technique

Improving energy conversion and utilization efficiency is a major issue that must be given priority in the implementation of sustainable development strategy in my country. In many energy utilization systems, there is a contradiction between energy supply and demand mismatch, resulting in irrational energy utilization and a large amount of waste. At present, the discharge of high-temperature flue gas and high-temperature waste heat in industry reaches 57000m3/h, and the temperature is 900-1100℃. Long-term emission not only wastes resources, but also causes non-negligible thermal pollution to the atmospheric environment. Recycling and utilizing the above-mentioned high-temperature waste heat can not only solve the thermal pollution of the environment, but also convert it into a usable form of energy, which has important application value and social benefits. High-temperature phase-change materials, especially metal phase-change materials, have the advantages of high melting point, high heat storage density, approximately isothermal heat absorption/release process, and easy control of the process, which can meet the requirements of recovering high-temperature flue gas and high-temperature waste heat. It is the current heat storage technology research hotspots in the field. Inorganic salts have great advantages in the application field of high-temperature phase change heat storage, so the current high-temperature heat storage phase change materials use inorganic salts or alloys as the main components. Molten salt, but its shortcomings in practical applications are also very prominent: molten salt is a very important type of heat storage material, which has the advantages of high operating temperature, large latent heat, high heat storage density, small degree of supercooling, and low cost. It has received widespread attention at home and abroad. However, molten salt has strong corrosion performance at high temperature, and has high requirements on the anti-corrosion performance of containers. Especially high temperature (above 500°C) molten salt heat storage materials basically corrode all stainless steels, which seriously restricts the use of molten salt. The large-scale application of heat storage materials makes it difficult to give full play to the advantages of high temperature, high phase change enthalpy and low cost of molten salt. Therefore, the development of integrated composite heat storage materials and molten salt corrosion-resistant coatings promotes the The industrial application of similar heat storage materials is of great significance.

Patent CN1328107A "An Inorganic Salt/Ceramic Composite Heat Storage Material and Its Preparation Method" introduces a high temperature phase change heat storage material, the main raw materials are _Na2CO3 20-30%, _BaCO318-28 %, MgO44-50% , Bi ₂ O 33-7%, or the composition is Na ₂ SO ₄ 45-53%, SiO ₂ 42-52%, Bi ₂ O 33-7%. After batching, ball milling, drying and press molding, high temperature sintering, the temperature is 850°C-1000°C. The preparation process is simple. This method has not actually controlled the corrosion resistance very well. Patent CN100999657A "Organic matter/expanded graphite composite phase change heat storage material and its preparation method and heat storage device" discloses the use of saturated fatty acids or linear alkanes as phase change materials, composited with graphite, filled in high thermal conductivity metal containers and packaged , used to quickly cool the heat generated by the chip when the electronic components are running. It solves the problems of supercooling, phase stratification and low thermal conductivity in the heat storage process, and does not involve the problem of corrosion resistance.

Contents of the invention

Therefore, the technical problem to be solved by the present invention is to provide an integrated package of high-temperature composite heat storage material and anti-corrosion coating for the current problems of leakage and corrosion of pure molten salt heat storage materials and molten salt/ceramic composite heat storage materials. method of preparation.

Technical scheme of the present invention is:

A method for preparing a high-temperature composite heat storage material and an anti-corrosion coating integrated package, including the heat storage material including the coating and the package, comprising the following steps:

(1) Preparation of heat storage material: mix and grind sodium carbonate and lithium carbonate at a mass ratio of 4:1 to 1:1 to obtain a binary molten salt, and then mix the binary molten salt and magnesium oxide at a mass ratio of 1:2 ～4:1 mixing, grinding evenly to form sodium carbonate lithium carbonate-magnesium oxide composite system;

(2) Coating preparation: Coating raw materials are high thermal conductivity and corrosion-resistant graphite and water glass ingredients. layer ingredients;

(3) Spread the above-mentioned coating ingredients on the bottom of the mold, and then put in a hollow cylindrical baffle whose size is smaller than that of the mold, add sodium carbonate lithium carbonate-magnesium oxide composite system to the inside of the baffle, and add a coating ingredient system to the outside of the baffle , and then pull out the baffle, and add a layer of coating ingredients on it;

(4) With a pressure of 5-30kPa and a holding time of 0.5-10min, press it into a cylindrical shape, and demold it into a molded sample; put the above-mentioned molded sample into an electric furnace, and sinter it at high temperature after passing through an inert atmosphere.

Water glass is sodium silicate solution. People are accustomed to use modulus to reflect the relative composition of SiO ₂ and Na ₂ O in water glass, and the molar ratio of SiO ₂ to Na ₂ O. When buying a product, only the modulus is used to indicate the product specification.

According to the high-temperature composite heat storage material and anti-corrosion coating integrated packaging preparation method of the present invention, preferably, the molded sample described in step (4) is placed in a graphite crucible and then placed in an electric furnace.

According to the high-temperature composite heat storage material and anti-corrosion coating integrated packaging preparation method of the present invention, preferably, the heating temperature of the high-temperature sintering is 530-660°C.

Further, the heating temperature of the high-temperature sintering is 550-650°C.

According to the preparation method of the high-temperature composite heat storage material and anti-corrosion coating integrated package of the present invention, preferably, after the high-temperature sintering in step (4), the temperature is lowered to room temperature.

According to the preparation method for the integrated packaging of the high-temperature composite heat storage material and the anti-corrosion coating of the present invention, preferably, the thickness of the coating is 5-10 mm. This thickness can achieve a better effect, and of course other thicknesses can be selected as required, such as 3-20mm.

Preferably, the inert gas is nitrogen or argon.

In order to solve the corrosion problem of the salt composite material, the present invention uses a relatively corrosion-resistant ceramic material as a matrix, and composites the inorganic salt and the ceramic matrix. However, during the use of molten salt phase change, a liquid phase will inevitably be generated, especially under high temperature conditions, inorganic salts are highly corrosive, and extremely stringent requirements are placed on the containers. Higher requirements are put forward for the thermal insulation and safety of the system. The feature of the present invention is to overcome the shortcomings of previous inventions and prepare an integrated package of high-temperature composite phase-change heat storage materials and anti-corrosion coatings. The present invention is neither a single molten salt nor a binary, ternary or quaternary composite heat storage material formed by using a molten salt loaded ceramic matrix MgO, but uses graphite and sodium silicate as ingredients for the anti-corrosion coating. Cold-pressed integrated molding, Na ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite integrated high temperature composite phase change heat storage material with corrosion resistance and high thermal conductivity was prepared. The high-temperature heat storage material prepared by the method has a heat storage density of 380-550kJ/kg, and a thermal conductivity of 3.0-4.1w/mk.

The beneficial effect of the present invention compared with prior art is:

1. To overcome the shortcomings of a single heat storage material and give full play to the advantages of composite materials, the use of high-conductivity graphite not only solves the corrosion performance of molten salts, but also enhances thermal conductivity and improves the heat exchange efficiency of heat storage materials.

2. The high-temperature phase-change molten salt and the coating are directly encapsulated through a briquette, and an integrated coating-coated high-temperature composite phase-change heat storage material is obtained after encapsulation. The method has simple preparation process and low cost, and is more suitable for large-scale industrial production.

3. The heat storage material prepared by the present invention has a long service life, is safe and reliable in application, and is more widely used.

Adopting the above-mentioned one-piece structure, the structure is simple, the safety and reliability of the heat storage system are ensured, and the heat exchange efficiency is high.

The product provided by the invention can not only be used for high-temperature composite phase-change heat storage materials for industrial waste heat recovery, but also can be used for solar thermal utilization, large-scale abandoned wind power utilization for heat storage, high-temperature flue gas recovery, cold-heat- Combined electrical systems, and the synthesis of composite materials and many other fields.

Detailed ways

Example 1:

Take 6 grams of sodium carbonate, 6 grams of lithium carbonate and 18 grams of magnesium oxide, mix and grind evenly to prepare 30 grams of inorganic salt/ceramic matrix mixture, and weigh 20 grams of the mixture. Get coating raw material graphite 5 grams and 0.5 gram 0.9 modulus sodium silicate solution and carry out batching. Distribute 2 grams of the above-mentioned coating ingredients evenly on the bottom of the mold, and then put it into a hollow cylindrical baffle whose size is smaller than that of the abrasive tool, add sodium carbonate lithium carbonate-magnesium oxide composite system to the inside of the baffle, and add Add the coating ingredient system, then pull out the baffle and add another layer of coating ingredient on top. The molding pressure on the hydraulic press is 6Mpa, and the pressure holding time is 10min. After demoulding, the pressed sample is placed into a graphite crucible, sintered and heated to 550°C in an inert atmosphere, and then lowered to room temperature after 1h of heat preservation. The final product is a corrosion-resistant and leak-proof Na ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite integrated heat storage material. The high-temperature heat storage material prepared by this method has a heat storage density of 380kJ/kg and a thermal conductivity of 3.0w/mk.

Example 2:

Take 8 grams of sodium carbonate, 2 grams of lithium carbonate and 10 grams of magnesium oxide, mix and grind evenly to prepare 20 grams of inorganic salt/ceramic matrix mixture, and weigh 15 grams of the mixture. Get coating raw material graphite 10 grams and 0.05 gram 1.3 modulus sodium silicate solution and carry out batching. Distribute 5 grams of the above-mentioned coating ingredients evenly on the bottom of the mold, and then put it into a hollow cylindrical baffle whose size is smaller than that of the abrasive tool, add sodium carbonate lithium carbonate-magnesium oxide composite system to the inside of the baffle, and add Add the coating ingredient system, then pull out the baffle and add another layer of coating ingredient on top. The molding pressure on the hydraulic press is 15Mpa, and the pressure holding time is 2min. After demoulding, the pressed sample is placed into a graphite crucible, sintered and heated to 650°C in an inert atmosphere, and then cooled to room temperature after 30min of heat preservation. The final product is a corrosion-resistant and leak-proof Na ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite integrated heat storage material. The high-temperature heat storage material prepared by this method has a heat storage density of 433kJ/kg and a thermal conductivity of 3.6w/mk.

Example 3:

Take 20 grams of sodium carbonate, 10 grams of sodium carbonate and 7.5 grams of magnesium oxide, mix and grind evenly to prepare 37.5 grams of inorganic salt/ceramic matrix mixture, and weigh 14 grams of the mixture. Get 10 grams of coating raw graphite and 0.1 gram of 1.1 modulus sodium silicate solution for batching. Weigh 2 grams of coating ingredients, first part of which is evenly distributed on the bottom of the mold, and then put into a hollow cylindrical baffle whose size is smaller than that of the abrasive tool, add sodium carbonate lithium carbonate-magnesium oxide composite system to the inside of the baffle, and add Add the coating ingredient system, then pull out the baffle and add another layer of coating ingredient on top. The molding pressure on the hydraulic press is 30Mpa, and the pressure holding time is 0.5min. After demoulding, the pressed sample is placed into a graphite crucible, sintered and heated to 600°C in an inert atmosphere, and then lowered to room temperature after 40min of heat preservation. The final product is a corrosion-resistant and leak-proof Na ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite integrated heat storage material. The high-temperature heat storage material prepared by this method has a heat storage density of 550kJ/kg and a thermal conductivity of 4.1w/mk.

The heat storage density of the Na ₂ CO ₃ Li ₂ CO ₃ -MgO heat storage material prepared without graphite coating packaging is basically unchanged, but its thermal conductivity is less than 2.1w/mk, and the number of cycles does not exceed 5000 times. In the Na ₂ CO ₃ Li ₂ CO ₃ -MgO/graphite integrated packaging high-temperature composite phase change heat storage material and coating prepared in Example 1, Example 2 and Example 3, Na ₂ CO ₃ Li ₂ CO ₃ -The thermal conductivity of MgO/graphite has increased by more than 30%. Due to the simultaneous prevention of molten salt leakage, the number of cycles has exceeded 16,000 times, and the service life has increased by more than 3 times.

Claims (7)

1. high temperature thermal energy storage material and a corrosion protection coating integral type encapsulation preparation method, comprises coating and is encapsulated in interior heat accumulating, it is characterized in that: comprise the following steps:

(1) heat accumulating preparation: be that 4:1 ~ 1:1 mixed grinding evenly obtains binary melting salt according to mass ratio by sodium carbonate, Quilonum Retard, then be 1:2 ~ 4:1 mixing in mass ratio by binary melting salt and magnesium oxide, after grinding evenly, form sodium carbonate Quilonum Retard-magnesium oxide compound system;

(2) coating preparation: coating material is high heat-conducting and corrosion-resistant graphite and water glass batching, and modulus of water glass is 0.9 ~ 1.3, and the ratio then adding 0.01 ~ 0.1 gram of water glass according to every gram of graphite system mixes, and forms coating compounding;

(3) by above-mentioned coating compounding tiling mold bottom, put into the hollow cylinder baffle plate that size is less than mould again, inside baffle plate, add sodium carbonate Quilonum Retard-magnesium oxide compound system, outside baffle plate, add coating compounding system, extract baffle plate out afterwards, add one deck coating compounding more above;

(4) with the pressure of 5 ~ 30kPa, the dwell time is 0.5min ~ 10min, is pressed into cylindric, and the demoulding is molded samples; Above-mentioned molded samples is put into electric furnace, passes into high temperature sintering after inert atmosphere.

2. high temperature thermal energy storage material according to claim 1 and corrosion protection coating integral type encapsulation preparation method, is characterized in that, put into electric furnace again after step (4) described molded samples is placed in plumbago crucible.

3. high temperature thermal energy storage material according to claim 1 and corrosion protection coating integral type encapsulation preparation method, it is characterized in that, the Heating temperature of described high temperature sintering is 530-660 DEG C.

4. high temperature thermal energy storage material according to claim 3 and corrosion protection coating integral type encapsulation preparation method, it is characterized in that, the Heating temperature of described high temperature sintering is 550-650 DEG C.

5. high temperature thermal energy storage material according to claim 1 and corrosion protection coating integral type encapsulation preparation method, is characterized in that, after step (4) described high temperature sintering, be cooled to room temperature.

6. high temperature thermal energy storage material according to claim 1 and corrosion protection coating integral type encapsulation preparation method, it is characterized in that, the thickness of described coating is 5 ~ 10mm.

7. the preparation method of heat accumulating wrapper according to claim 1, is characterized in that, described rare gas element is nitrogen or argon gas.