Molten salt, the molten body formed after the melting of salts, such as the molten body of halides, nitrates and sulfates of alkali metals and alkaline earth metals. Molten salt is a molten body composed of metal cations and non-metallic anions. There are more than 80 kinds of cations and more than 30 kinds of anions that can form molten salt, and the combined molten salt can reach more than 2400 kinds. Because metal cations can have several different valence states, anions can also form different complex anions. In fact, the number of molten salts will exceed 2400.
Molten salt is a kind of salt that is solid at standard temperature and atmospheric pressure, and exists in liquid state after the temperature rises. Molten inorganic salt is usually called molten salt. It now includes oxide melt and molten organic matter.
Molten salt has the characteristics of high melting point, high hardness, high thermal conductivity, high conductivity, wear resistance and thermal stability. It is a high-temperature heat transfer and heat storage medium with excellent performance. It has great application value in the fields of photothermal power generation, waste air and waste light molten salt heat storage heating, molten salt heat storage peak shaving power station, intermittent high-temperature industrial waste heat recovery, high-temperature industrial heat transfer, etc, The market space is huge.
Molten salt composition:
Binary Molten Salt
Binary molten salt (60% sodium nitrate + 40% potassium nitrate) is a mature heat storage medium proved by practical cases to be suitable for photothermal power generation system. However, for the field of medium temperature heat utilization, this binary molten salt cannot be used, mainly because its freezing point is too high, about 207 ℃. For the medium temperature heat utilization system with the working temperature of about 250 ℃, the molten salt product with freezing point must be used.
Ternary molten salt
Ternary molten salt (i.e. mixed nitrate composed of 53% potassium nitrate + 40% sodium nitrite + 7% sodium nitrate) has a melting point of 142 ℃ and a gasification point of 500 ℃. Sodium nitrite will decompose slowly above 450 ℃, but the working temperature of medium temperature heat utilization system is generally within 250 ~ 350 ℃
Application of molten salt heat storage in engineering and photothermal power generation