Device and process under conditions close to the supercritical range or under supercritical conditions

1. A process comprising the steps of:

entering, into a device, an aqueous fluid containing at least one inorganic salt, the water of the aqueous fluid in the device being under supercritical conditions or close to the supercritical range,

measuring the concentration or the amount of inorganic salt in the device,

contacting the inorganic salt with an aqueous stream containing at least one hydroxide salt, so as to obtain an aqueous fluid mixture in the device containing an inorganic salt and a hydroxide salt, and

adjusting the concentration or amount of the hydroxide salt as a function of the concentration or amount of the inorganic salt needed to at least partially solubilize the inorganic salt.

2. The process according to claim 1 , wherein adjusting the concentration or the amount of the hydroxide salt according to the concentration or the amount of the inorganic salt is carried out at least one of repeatedly, discontinuously or continuously.

3. The process according to claim 1 , wherein adjusting the concentration or the amount of the hydroxide salt as a function of the concentration or the amount of the inorganic salt comprises monitoring the concentration of inorganic salt at an inlet and/or at an outlet of the device.

4. The process according to claim 1 , wherein the aqueous mixture is heated to between 300° C. and 600° C., and brought to a pressure between 22.1 and 50 MPa.

5. The process according to claim 1 , wherein the aqueous mixture is heated to between 350° C. and 550° C., and brought to a pressure between 22.1 and 50 MPa.

6. The process according to claim 1 , wherein the aqueous fluid containing at least one inorganic salt further comprises organic compounds.

7. The process according to claim 1 , wherein the hydroxide salt is chosen from among potassium hydroxide, sodium hydroxide and lithium hydroxide.

8. The process according to claim 1 , wherein the aqueous fluid containing the hydroxide salt is injected into the device alternately with the aqueous fluid containing the inorganic salt.

9. The process according to claim 1 , wherein the aqueous fluid containing the hydroxide salt is mixed with the aqueous fluid containing the inorganic salt before the latter enters the device.

10. The process according to claim 1 , wherein the aqueous fluid containing the hydroxide salt is injected discontinuously by pulse into the device.

11. The process according to claim 10 , wherein the pressure differential between an inlet and an outlet of the device is measured, and the aqueous fluid containing the hydroxide salt is injected when said pressure differential exceeds a predetermined threshold value.

12. The process according to claim 1 , comprising a preliminary step of measuring the solubility of the hydroxide salt in the aqueous fluid mixture under supercritical conditions.

13. The process according to claim 1 , comprising a preliminary step of measuring the solubility of the inorganic salt in the hydroxide salt being molten under supercritical conditions.

14. The process according to claim 1 , wherein the process is a supercritical hydrothermal oxidation process for the treatment of an aqueous fluid containing inorganic salts.

15. The process according to claim 1 , wherein the measurement of the concentration or the amount of inorganic salt in the device is carried out before the entry of the inorganic salt into the device.

16. The process according to claim 1 , further comprising the measurement of the concentration or the quantity of inorganic salt leaving the device.

17. A device capable of operating in supercritical conditions comprising:

a heating and pressurizing device capable of placing water in conditions close to the supercritical range(s) or under supercritical conditions,

a first line introducing into the device an aqueous fluid containing at least one inorganic salt,

a measuring device measuring the concentration or the amount of inorganic salt in the device,

a second line bringing the inorganic salt into contact with an aqueous fluid flow containing at least one hydroxide salt in order to obtain in the device an aqueous fluid mixture containing an inorganic salt and a hydroxide salt, and

an adjustment device adjusting the concentration or the amount of the hydroxide salt as a function of the concentration or the amount of the inorganic salt to at least partially dissolve the inorganic salt.

18. The device according to claim 17 , wherein the measurement of the concentration or the amount of inorganic salt in the device is carried out before the entry of the inorganic salt into the device.

19. The device according to claim 17 , further comprising a device for measuring the concentration or the amount of inorganic salt leaving the device.

20. A device capable of operating in supercritical conditions comprising:

a heating and pressurizing device capable of placing water under conditions close to the supercritical range(s) or under supercritical conditions,

a first line introducing into the device an aqueous fluid containing at least one inorganic salt,

a measuring device measuring the concentration or amount of inorganic salt entering the device,

a second line bringing the inorganic salt into contact with an aqueous fluid stream containing at least one hydroxide salt in order to obtain in the device an aqueous fluid mixture containing an inorganic salt and a hydroxide salt, said second line comprising a filter capable of retaining precipitated inorganic salts, and capable of causing the hydroxide salt in a molten state to flow less rapidly than the aqueous fluid, and

a second measuring device measuring the saturation concentration of the hydroxide salt in the aqueous fluid mixture.