Nitrate molten salt heat transferring and reserving medium and preparation method and application thereof

Abstract

The invention discloses a nitrate molten salt heat transferring and reserving medium and a preparation method and application thereof. The nitrate molten salt heat transferring and reserving medium is prepared with 5 to 40 percent of potassium nitrate, 5 to 25 percent of sodium nitrate, and 10 to 70 percent of calcium nitrate. The melting point of the nitrate molten salt heat transferring and reserving medium can be as low as 120 DEG C, and the upper limit of temperature for use can reach 550 DEG C, the nitrate molten salt heat transferring and reserving medium has a wide temperature scope of application, can work normally at the temperature scope of 180 DEG C to 550 DEG C, and has good thermal stability; the shortcoming of high melting point of binary nitrate molten salt system can be overcome, and the problem of instability caused by easy oxidative decomposition at high temperature of NaNO2 in the Chinese patent 200110027954.1 and ternary nitrate salt system can be solved, and the problems of corrosion and cost increase caused by the existing LiNO3 in the Chinese patent 00111406.9 and the American patent US007588694B1 can also be solved.

Description

technical field [0001] The invention belongs to the field of industrial energy storage and solar high-temperature heat utilization, and specifically relates to a heat transfer and heat storage medium, in particular to a nitric acid molten salt heat transfer and heat storage medium and its preparation method and application. Background technique [0002] Energy storage technology has a wide range of applications in industrial energy conservation and renewable energy utilization. However, the efficiency of energy utilization in my country's large-scale industrial fields is low, and renewable energy has the disadvantages of intermittent and non-continuous energy supply. storage and transportation issues. [0003] In industrial energy storage and solar high-temperature heat utilization technologies, the heat transfer and heat storage media currently used mainly include air, water / steam, hydrated salts, paraffins, fatty acids, and molten salts. Among them, molten salt as a heat ...

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Problems solved by technology

Although the melting point of the ternary nitrate system is relatively low, the upper limit use temperature is also low

[0006] In order to solve the above problems, Chinese patent application 00111406.9 discloses a kind of L i NO 3 -KNO 3 -N a NO 3 -N a NO 2 system, its working temperature range is 250°C to 550°C, the upper limit working temperature of this system is higher than the ternary nitrate system, reaching 550°C, but its lower limit working temperature is also increased, and because L i NO 3 The addition of it increases its corrosiveness and costs

[0007] Chinese patent application 200110027954.1 discloses a nitrate system, which has the same melting point as ternary nitric acid molten salt, with an upper limit working temperature of 550°C, but NaNO in the system 2 It is prone to high-temperature oxidation and decomposition, and has high requirements on the ambient atmosphere

[0008] In addition, U.S. Patent US007588694B1 discloses a kind of L i NO 3 -KNO 3 -N a NO 3 -Ca(NO 3 ) 2 system, its melting point is lower than 100°C, and the upper limit use temperature is higher than 500°C, this system has a lower melting point than the ternary nitric acid molten salt system, but contains L i NO 3 Also increases the corrosion and cost of molten salt

[0009] Patents with application numbers 200810027638.9 and 200910037348.7 also provide a carbonate molten salt system, but the melting point of these two systems is above 400°C, which is not suitable for industrial energy storage and high-temperature solar heat utilization

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