DE2336911A1 - QUATERNAERE, EUTECTIC LIFE-HOLDING SALT MIX - Google Patents

Description

PHN.70T1 «/ EVH.

Applicant: NV Piui. ϊ

. File: PHN- 7011
Announcement of July 19, 1973

Quaternary, eutectic LiP-containing salt mixture

There is a need in the art for materials having a melting point between 100 and 500 ° C that are a
Have the greatest possible heat of fusion and heat capacity and which are not corrosive to common vessel materials such as chrome-nickel steel.

Materials of this type can be used as heat storage material e.g. in solar power plants, in storage stoves and the like, as a heat transport material e.g. in nuclear reactors and in salt baths find application for heat treatment.

A ternary eutectic mixture is known which melts at 454 ° C and consists of 6.5 mol LiP, 420 mol KP and 11.5 mol NaP.

409886/0685

- 2 - _% PHN.7011.

Such a material can be used in enormously large quantities, particularly in power plants such as solar power plants. The rather high price and relative rarity of lithium fluoride could be a serious factor in such circumstances. The invention creates a salt mixture with a eutectic melting point between 400 and 500 ° C., which is characterized in that it contains approx. 44 mol $ LiF, approx. 40 mol 5 & KF, approx. 12 mol # NaF and approx. 4 mol $ MgF ₂ . The melting point of the eutectic mixture is about 4 ^ 9 ^° C. The heat of fusion is about 167 Cal / g and is thus about 2 »5 $ higher than that of the eutectic mixture of LiF, KF and NaF (heat of fusion about 163 Cal / g ). With the same storage capacity as the heat of fusion, one can get along with a smaller amount of the invented salt mixture than with the known mixture. In addition, the invented mixture contains less LiF, which means an extra saving in expensive LiF.

A quaternary salt mixture of 44.9 mol # LiF, 40.6 mol # KF, 11.5 mol ^ NaF and 3 mol # CaF ₂ with a melting point of 444 ^° C. has already been proposed as a heat storage material (FR-PS 1 524 997 ). This mixture contains more lithium fluoride than the invented mixture and, at approx. 159 Cal / g, has a lower heat of fusion than the known mixture of LiF, KF and NaF and than the invented mixture.

The new salt mixture can be obtained as follows: A salt mixture is shown which

409886/0685

- 3 - PHN.7011.

44 mol # + _ 2 mol # LiF;

12 mol # + _ 1 mol #. NaF;

40 mol # i 2 mol # KF and

4 raol # + _ 1 mol $ MgF ~ ^βηΐΐ131 * · ^The mixture will
repeatedly melted and slowly cooled again until a clear melt is obtained ^{when again melting below 450 ° C.} The melt will eventually be released by one at this temperature
Poured off the not melted residue and cooled that
The composition of the melt now corresponds to the eutectic mixture with approximately: Composition: hk mol $ LiF, 4θ mol $ KF, 12 mol # NaF and 4 mol # MgF _£ .

The salt mixture can be used as a heat storage material and as a heat transport material. The mixture is chemically stable, non-flammable and non-corrosive to chrome-nickel steel; it does not develop fumes during use,
which is important for use in closed containers.

409886/0685

Claims (4)

EXPECTATIONS: 1, LiP-containing salt mixture with eutectic melting point between 400 and 50O ⁰ C, characterized in that it contains approx. 44 mol of LiF, approx. 40 mol of KP, approx. 12 mol of NaF and approx. Contains 4 mol $ MgP ₂ . 2. A method for producing a LiP-containing salt mixture according to claim 1, characterized in that a salt mixture of 44 mol $, + 2 mol $ LiF, 12 mol $ + _ 1 mol $ NaF, 40 mol ^ _ + 2 mol ^ o KP and 4 mol $ 4_ 1 mol ^ MgP _{2 is} shown and repeatedly melted and cooled until a ^{clear melt melting below 450 0} C is obtained, which is poured off from the residue that may not have melted at this temperature, 3 · Heat storage or heat transport system in one LiP-containing salt mixture according to claim 1 for use comes, 409886/0685