Method of improving nitrate salt compositions by means of nitric acid for use as heat transfer medium or heat storage medium

Patent metadata

Field	Value
Publication number	US-10011754-B2
Application number	US-201414161764-A
Country	US
Kind code	B2
Filing date	Jan 23, 2014
Priority date	Jan 23, 2013
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

Method of maintaining or widening the long-term operating temperature range of a heat transfer medium and/or heat storage medium comprising a nitrate salt composition selected from the group consisting of alkali metal nitrate and alkaline earth metal nitrate and optionally alkali metal nitrite and alkaline earth metal nitrite, wherein the nitrate salt composition is brought into contact with an additive comprising the components nitric acid and/or nitrous acid and oxygen-comprising gas having an oxygen partial pressure which is equal to or greater than that in air and/or oxygen-generating compounds and optionally nitrogen oxides and/or compounds which generate further nitrogen oxide.

First claim

The invention claimed is:

1. A method of maintaining or widening the long-term operating temperature range of a heat transfer medium and/or heat storage medium comprising a nitrate salt composition selected from the group consisting of alkali metal nitrate, alkaline earth metal nitrate, and combinations thereof, and optionally alkali metal nitrite and alkaline earth metal nitrite, the process comprising:
bringing the nitrate salt composition into contact with an additive comprising nitric acid and nitrous acid and oxygen-comprising gas selected from the group consisting of air, pure elemental oxygen, and mixtures of oxygen with other gases where the proportion of oxygen, based on the gas mixture and measured at 1013.25 hPa and 20° C. is in the range from 22 to 99.9% by volume, and optionally nitrogen oxides and/or compounds which generate further nitrogen oxide;
wherein the contacting results in complete neutralization of the nitrate salt composition or setting of a residual basicity in the nitrate salt composition.

2. The method according to claim 1 , wherein the contacting of the additive with the nitrate salt composition occurs in a reaction space which comprises a partial amount of the heat transfer medium.

3. The method according to claim 2 , wherein at least a portion of the heat transfer medium is present in a main stream and the reaction space is arranged in parallel to the main stream.

4. The method according to claim 1 , wherein the method further comprises completely or partly removing water which has either been introduced via the additive contacted with the nitrate salt composition or has been formed in the method.

5. The method according to claim 1 , wherein the heat transfer medium and/or heat storage medium is used in power stations for generating heat and/or electricity, in chemical process technology or in metal hardening plants.

6. The method according to claim 5 , wherein the power stations for generating heat and/or electricity are solar thermal power stations.

7. The method according to claim 6 , wherein the solar thermal power stations are of the parabolic trough power station, Fresnel power station or tower power station type.

8. The method according to claim 1 , wherein the nitrate salt composition is taken off from the bottom of a cold part of a heat storage system.

9. A process system in which pipes and vessels and/or apparatuses are connected and in which a heat transfer medium and/or heat storage medium comprising the nitrate salt composition defined in claim 1 is present, wherein the nitrate salt composition is brought into contact with the additive as defined in claim 1 .

10. A power station for generating heat and/or electricity, a chemical plant or a metal hardening plant comprising the process system according to claim 9 .

11. The power station according to claim 10 , wherein the plant for generating heat and/or electricity is a solar thermal power station.

12. The method according to claim 1 , wherein the heat transfer medium and/or heat storage medium comprises alkali metal nitrite or alkaline earth metal nitrite.

13. The method according to claim 1 , wherein the additive comprises nitrogen oxides and/or compounds which generate further nitrogen oxide.

14. A method of generating electric energy in a solar thermal power station comprising:
heating a heat transfer medium by solar radiation;
exchanging heat with water in a heat exchanger; and
driving a generator to generate electric energy;
wherein the heat transfer medium is a nitrate salt composition selected from the group consisting of alkali metal nitrate, alkaline earth metal nitrate, and combinations thereof, and wherein all or part of the nitrate salt composition is brought into contact with an additive comprising nitric acid and nitrous acid and oxygen-comprising gas selected from the group consisting of air, pure elemental oxygen, and mixtures of oxygen with other gases where the proportion of oxygen, based on the gas mixture and measured at 1013.25 hPa and 20° C. is in the range from 22 to 99.9% by volume;
wherein the contacting results in complete neutralization of the nitrate salt composition or setting of a residual basicity in the nitrate salt composition.

Assignees

• Basf Se

Inventors

• Wortmann Jürgen
• Lutz Michael
• Ter Maat Johan
• Schierle-Arndt Kerstin
• Maurer Stephan
• Ladenberger Michael
• Garlichs Florian
• Kaleta Katharina

Classifications

• C09K5/12 Primary

  Molten materials, i.e. materials solid at room temperature, e.g. metals or salts · CPC title

• Y02E10/40

  Solar thermal energy, e.g. solar towers · CPC title

• F24S80/20

  Working fluids specially adapted for solar heat collectors · CPC title

• F28D2020/0047

  using molten salts or liquid metals · CPC title

• F24J2/4649

  Mechanical Engineering · mapped topic