Monitoring particles in a fluid flow

1. Apparatus for use in monitoring particles in a liquid flow, comprising: a duct in the form of a pipe section for receiving the liquid flow;

light generating means adjacent the pipe section for transmitting light into the liquid flow via a first at least partially light-transmissive part of the pipe section;

light-responsive detection means adjacent a second at least partially light-transmissive part of the pipe section for receiving light from the light generating means which light has passed through the liquid flow;

processing means for location remotely from said pipe section;

means for coupling the processing means with the detection means, the processing means being adapted for processing signals therefrom to provide data relating to particles in the liquid flow;

wherein inside said pipe section, each of said first and second at least partially light-transmissive parts has a non-stick coating;

the surface of said first at least partially light-transmissive part inside said pipe section is uneven for reducing deposit build-up on said surface.

2. Apparatus according to claim 1 , wherein said pipe section is provided with means for mounting said pipe section in a run of pipework.

3. Apparatus according to claim 1 , wherein said first and second at least partially light-transmissive parts comprise first and second windows in a wall of the pipe section.

4. Apparatus according to claim 1 , wherein said first and second at least partially light-transmissive parts are diametrically opposite each other.

5. Apparatus according to claim 1 , wherein said flushing means is located downstream of said first and second at least partially light-transmissive parts.

6. Apparatus according to claim 1 , wherein said flushing means comprises, for each of said first and second at least partially light-transmissive parts, a respective nozzle for directing a flushing liquid at the respective part from inside the pipe section.

7. Apparatus according to claim 1 , wherein said camera is provided with a lens and frame grabbing means for capturing one magnified single image at a time, said lens and frame grabbing means focussed inside said pipe section, the signals received by said processing means representing successive captured images from said grabbing means.

8. Apparatus according to claim 1 , wherein said processing means provides data relating to the amount and/or size distribution of particles of a predetermined kind in the liquid flow.

9. Apparatus according to claim 1 , including a plurality of light-responsive detection means.

10. Apparatus according to claim 9 , wherein only one of said light-responsive detection means is used at a time.

11. Apparatus according to claim 9 , wherein each of said light-responsive detection means receives light from said second at least partially light-transmissive part.

12. Apparatus according to claim 1 , including a plurality of first at least partially light-transmissive parts.

13. Apparatus according to claim 12 , including a plurality of second at least partially light-transmissive parts, each of which is associated with a respective one of said first at least partially light-transmissive parts.

14. Apparatus according to claim 13 , including a plurality of light-responsive detection means, wherein each of said light-responsive detection means receives light from a respective one of said second at least partially light-transmissive parts.

15. Apparatus according to claim 12 , wherein said pipe section is provided with means for flushing away deposits from each of said first and second at least partially light-transmissive parts inside the pipe section and wherein each of said first and second at least partially light-transmissive parts is associated with respective flushing means.

16. Apparatus according to claim 1 , wherein there is a plurality of light generating means.

17. Apparatus according to claim 16 , wherein only one of said light generating means is used at a time.

18. Apparatus according to claim 16 , including a plurality of such first at least partially light-transmissive parts and wherein each of said light generating means is associated with a respective one of said first at least partially light-transmissive parts.

19. Apparatus according to claim 1 , with said pipe section mounted in pipework for conveying the liquid flow, the processing means being located at a location remote therefrom and the coupling means coupling the processing means and the light-responsive detection means.

20. Apparatus according to claim 19 , wherein said pipework is adapted to convey water into a well in a hydrocarbon production system.

21. Apparatus according to claim 20 , wherein said pipe section, the first and second light-transmissive parts, the light generating means and the light-responsive means are sub-sea.

22. Apparatus according to claim 21 , wherein said remote location is a topside platform.

23. Apparatus according to claim 1 wherein said pipe section is provided with means for flushing away deposits from each of said first and second at least partially light-transmissive parts inside the pipe section.

24. Apparatus according to claim 1 wherein said light-responsive detection means comprises a television camera.