Device and method for making a dilute aqueous solution of peroxomonosulphuric acid

1. A device for making a dilute aqueous solution of peroxomonosulphuric acid, comprising:

a) a conduit for an aqueous stream;

b) a mixing tube located inside said conduit, having a static mixer inside the mixing tube, an outlet open to said conduit and an inlet;

c) a sulphuric acid supply tube connected to the inlet of said mixing tube; and

d) a hydrogen peroxide supply tube, arranged inside the sulphuric acid supply tube and having an outlet for hydrogen peroxide at the inlet of said mixing tube.

2. The device of claim 1 , wherein said mixing tube and said sulphuric acid supply tube are arranged coaxially inside said conduit.

3. The device of claim 2 , wherein the outlet of said mixing tube is in the flow direction of said aqueous stream.

4. The device of claim 1 , further comprising a sulphuric acid feed line to said sulphuric acid supply tube, the sulphuric acid feed line having a non-return valve, and a hydrogen peroxide feed line to said hydrogen peroxide supply tube, the hydrogen peroxide feed line having a non-return valve.

5. The device of claim 4 , wherein said mixing tube and said sulphuric acid supply tube are arranged coaxially inside said conduit.

6. The device of claim 5 , wherein the outlet of said mixing tube is in the flow direction of said aqueous stream.

7. The device of claim 1 , further comprising flow interrupting devices, controlled by a flow indicator for said aqueous stream, for stopping supply of sulphuric acid to said sulphuric acid supply tube and of hydrogen peroxide to said hydrogen peroxide supply tube.

8. The device of claim 7 , wherein said mixing tube and said sulphuric acid supply tube are arranged coaxially inside said conduit.

9. The device of claim 8 , wherein the outlet of said mixing tube is in the flow direction of said aqueous stream.

10. The device of claim 7 , further comprising a sulphuric acid feed line to said sulphuric acid supply tube, the sulphuric acid feed line having a non-return valve, and a hydrogen peroxide feed line to said hydrogen peroxide supply tube, the hydrogen peroxide feed line having a non-return valve.

11. The device of claim 1 , further comprising an additional static mixer located in said conduit downstream from the outlet of said mixing tube.

12. The device of claim 11 , wherein said mixing tube and said sulphuric acid supply tube are arranged coaxially inside said conduit.

13. The device of claim 12 , wherein the outlet of said mixing tube is in the flow direction of said aqueous stream.

14. The device of claim 11 , further comprising a sulphuric acid feed line to said sulphuric acid supply tube, the sulphuric acid feed line having a non-return valve, and a hydrogen peroxide feed line to said hydrogen peroxide supply tube, the hydrogen peroxide feed line having a non-return valve.

15. A method for making a dilute aqueous solution of peroxomonosulphuric acid, wherein:

a) an aqueous stream is passed through the conduit of a device according to claim 1 ;

b) 85 to 98% by weight sulphuric acid is introduced to the sulphuric acid supply tube of said device; and

c) 50 to 80% by weight aqueous hydrogen peroxide solution is introduced to the hydrogen peroxide supply tube of said device.

16. The method of claim 15 , wherein sulphuric acid and hydrogen peroxide are introduced at a molar ratio of from 0.5 to 10.

17. The method of claim 15 , wherein the sulphuric acid and hydrogen peroxide are introduced at rates to provide a weight ratio of the aqueous stream relative to the combined amount of sulphuric acid and hydrogen peroxide within the range from 1 to 10.