Hydrocyclone

1. A separating cyclone for separating a mixture of liquids and/or gases into a heavy fraction with one or more liquids and/or gases of a relatively high specific mass and a light fraction with one or more liquids and/or gases of a relatively low specific mass, the cyclone comprising:

a cyclone tube in which a flow space is defined, wherein the cyclone tube is provided with an inlet for infeed of the mixture, a heavy fraction outlet for discharging the heavy fraction separated from the mixture and a light fraction outlet for discharging the light fraction separated from the mixture;

a rotation generating unit for setting the mixture into rotation;

a flow body arranged substantially concentrically in the cyclone tube and comprising a light fraction discharge channel connected to the light fraction outlet, the discharge channel comprising a channel portion having a cross-section which decreases in the flow direction;

a first pressure control element connected to the heavy fraction outlet for adjusting the flow rate of the heavy fraction;

a second pressure control element connected to the light fraction outlet for adjusting the flow rate of the light fraction; and

control means configured to control the first and second pressure control elements to cause the interface between the heavy fraction and light fraction to make contact with an inner surface of the discharge channel during use.

2. The separating cyclone as claimed in claim 1 , wherein the control means are adapted to cause said interface to make contact with an inner surface of said channel portion during use.

3. The separating cyclone as claimed in claim 1 , wherein said channel portion has a cross-section which decreases substantially uniformly in the flow direction.

4. The separating cyclone as claimed in claim 3 , wherein said channel portion has a substantially conical form.

5. The separating cyclone as claimed in claim 1 , wherein said channel portion has a cross-section decreasing progressively in the flow direction.

6. The separating cyclone as claimed in claim 1 , wherein the channel portion has a cross-section decreasing degressively in the flow direction.

7. The separating cyclone as claimed in claim 1 , wherein the channel portion is located proximate an inflow opening of the discharge channel.

8. The separating cyclone as claimed in claim 7 , wherein the channel portion connects onto the inflow opening of the discharge channel.

9. The separating cyclone as claimed in claim 1 , wherein the rotation generating unit comprises one or more guide fins through which the mixture is directed.

10. The separating cyclone as claimed in claim 1 , wherein the rotation generating unit comprises a tangential inlet element.

11. The separating cyclone as claimed in claim 1 , wherein the rotation generating unit comprises a flow element provided substantially concentrically in the flow space and one or more guide fins arranged between the cyclone tube and the flow element.

12. The separating cyclone as claimed in claim 11 , wherein the flow body and the flow element are integrated.

13. The separating cyclone as claimed in claim 11 , wherein the flow body is positioned downstream relative to the flow element.

14. The separating cyclone as claimed in claim 13 , further comprising an elongate element which is arranged between the flow body and the flow element and which extends concentrically relative to the discharge channel for the purpose of stabilizing the rotating light fraction.

15. The separating cyclone as claimed in claim 14 , wherein the elongate element extends into the discharge channel.

16. The separating cyclone as claimed in claim 11 , wherein the flow element comprises a substantially conically formed outer end.

17. The separating cyclone as claimed in claim 1 , further comprising a passage which is connected to the heavy fraction outlet and is defined between the inner side of the cyclone tube and the outer side of the flow body.

18. The separating cyclone as claimed in claim 17 , further comprising one or more rotation reducing units located in the passage for reducing the rotation of the heavy fraction flowing therealong.

19. The separating cyclone as claimed in claim 1 , further comprising one or more rotation reducing units located in the discharge channel for reducing rotation of the light fraction flowing therealong.

20. The separating cyclone as claimed in claim 1 , wherein the mixture comprises a mixture of oil and water and the separating cyclone operates to separate the mixture into a substantially water-containing heavy fraction and a substantially oil-containing light fraction.

21. The separating cyclone as claimed in claim 1 , further comprising a number of guide fins located between the flow body and the cyclone tube, and wherein the discharge channel extends through the flow body and through at least one of the guide fins.

22. The separating cyclone as claimed in claim 1 , wherein the separating cyclone comprises two successively coupled separating cyclones, wherein the separated heavy fraction from one separating cyclone is carried into the other separating cyclone for the purpose of further separation into a heavy fraction and a light fraction.