Device for the enrichment of a liquid stream with a gas

1. A device for enriching a liquid stream with a gas, said device comprising:

a flow-through mixer with a Venturi nozzle that has a rotationally symmetric constriction with a diameter D and through which the liquid stream can flow axially, the Venturi nozzle further including an inlet section converging in a direction of flow of the liquid stream and an outlet section diverging in said direction of flow, said inlet section and said outlet section each having an opening angle, said opening angle of the inlet section being substantially more acute than said opening angle of said outlet section, wherein said outlet section opens into a cylindrical expansion chamber, said cylindrical expansion chamber having a diameter about 8 to 12 times larger than said diameter D of said constriction; and

a gas feed for laterally feeding in the gas into said constriction of said Venturi nozzle;

wherein said gas feed comprises at least one gas channel that has a diameter d<0.5 D and a longitudinal axis, said gas feed laterally opening into said constriction of said Venturi nozzle so that its longitudinal axis is tangential to an imaginary cylinder surface that is coaxial with said constriction and has a diameter D′>d.

2. The device according to claim 1 , wherein D′=D−d.

3. The device according to claim 1 , wherein 0.25 D<d<0.5 D.

4. The device according to claim 1 , wherein said constriction of said Venturi nozzle is formed by a cylindrical channel with a diameter D and with a length that corresponds approximately to its diameter D.

5. The device according to claim 1 , wherein said opening angle of said inlet section is about 2.5 to 3 times smaller than said opening angle of said outlet section.

6. The device according to claim 1 , further comprising a vortex device, wherein said Venturi nozzle has an inlet section converging in a direction of flow of the liquid stream and said vortex device is directly positioned in front of said converging inlet section of said Venturi nozzle.

7. The device according to claim 6 , wherein said vortex device comprises a body with an inlet cone converging in said direction of flow, with an axial bore and with an oblique bore, said cone opening into said axial bore and into said oblique bore.

8. The device according to claim 1 , further comprising a cylindrical expansion chamber and a baffle plate insert with through-holes, wherein said Venturi nozzle opens into said cylindrical expansion chamber and said cylindrical expansion chamber is axially delimited by said baffle plate insert.

9. The device according to claim 1 , wherein said gas feed comprises a plurality of gas channels, each of said plurality of gas channels having a diameter d<0.5 D and a longitudinal axis, wherein each of said plurality of gas channels opens into said constriction of said Venturi nozzle laterally so that its longitudinal axis is tangential to an imaginary cylinder surface that is coaxial with said constriction and has a diameter D′>d.

10. The device according to 9 , wherein all of said plurality of gas channels introduce gas in the same direction into the constriction.

11. The device according to claim 10 , wherein said longitudinal axes of said plurality of gas channels have contact points with the imaginary cylinder surface, said contact points being angularly separated by an angle of 360°/said plurality of gas channels.

12. The device according to claim 1 , wherein said gas feed comprises a gas pressure control valve for controlling gas pressure as a function of pressure in the liquid stream.

13. The device according to claim 1 , wherein two gas channels open into said constriction and said gas feed comprises a valve control, said valve control being configured to apply gas to either one or two gas channels, depending on pressure in the liquid stream.

14. A device for enriching a liquid stream with a gas, said device comprising:

a flow-through mixer with a Venturi nozzle that has a rotationally symmetric constriction with a diameter D and an axis of symmetry, the Venturi nozzle further including an inlet section converging in a direction of flow of the liquid stream and an outlet section diverging in said direction of flow, said inlet section and said outlet section each having an opening angle, said opening angle of the inlet section being substantially more acute than said opening angle of said outlet section, wherein said outlet section opens into a cylindrical expansion chamber, said cylindrical expansion chamber having a diameter about 8 to 12 times larger than said diameter D of said constriction; and

a gas feed for laterally feeding in the gas into said constriction of said Venturi nozzle;

wherein said gas feed comprises at least one gas channel that has a diameter d<0.5 D and a longitudinal axis, said gas feed laterally opening into said constriction of said Venturi nozzle and so that its longitudinal axis is perpendicular to said axis of symmetry of said constriction.

15. The device according to claim 14 , wherein said gas feed comprises a plurality of gas channels, each gas channel having a diameter d<(1/plurality of gas channels)D and a longitudinal axis, wherein each of said plurality of gas channels opens into said constriction of said Venturi nozzle laterally and so that its longitudinal axis is perpendicular to said axis of symmetry of said constriction.

16. The device according to claim 15 , wherein said plurality of gas channels includes more than 2 gas channels, and said longitudinal axes of said plurality of gas channels lying in a same plane and defining a regular polygon in said plane.

17. The device according to claim 14 , wherein said constriction of said Venturi nozzle is a cylindrical channel with a diameter D and with a length that corresponds approximately to its diameter D.