Apparatus and process for locating and for measuring variations in temperature and/or in degree of fouling over the internal surface of equipment

1. Apparatus comprising an item of equipment made of material M 1 having external walls, an outer surface of the walls of the equipment being surrounded by, and in thermal contact with, at least one optical fibre F 1 , the optical fibre being connected to a system for measuring a temperature profile along the optical fibre F 1 , at least one layer i of material Mi of thermally insulating material separate from and covering the optical fibre F 1 and the outer surface of the walls of the equipment in the region where the optical fibre F 1 is located, wherein an external surface of the at least one layer i of material Mi covering the optical fibre F 1 is surrounded by, and in thermal contact with, at least one optical fibre Fi connected to a system for measuring a temperature profile along the optical fibre Fi.

2. Apparatus according to claim 1 , wherein the equipment made of material M 1 is a chemical reactor, a separator or an air-operated transport device.

3. Apparatus according to claim 2 , wherein the equipment made of material M 1 is a chemical polymerization reactor.

4. The apparatus of claim 3 , wherein the reactor is a fluidized-bed polymerization reactor.

5. The apparatus of claim 4 , wherein the reactor is a gas-phase fluidized-bed polymerization reactor.

6. Apparatus according to claim 1 , wherein an outermost layer of material surrounding the equipment is layer i made of thermally insulating material Mi.

7. Apparatus according to claim 1 , wherein the optical fibre F 1 is arranged in a succession of spiraled coils, each coil covering a sensitive region of the outer surface of the walls of the equipment.

8. Apparatus according to claim 1 , wherein the optical fibre F 1 is arranged in a helical coil around the outer surface of the walls of the equipment with a pitch chosen according to a resolving power of the fibre and to a region of the equipment where it is desired to measure the temperature.

9. Apparatus according to claim 8 , wherein each coil has a length equal to an elementary length of the optical fibre F 1 and covers an elementary area of the outer surface of the walls of the equipment.

10. Apparatus according to claim 7 or 8 , wherein the optical fibre Fi is placed on and attached to the external surface of the layer i of material Mi in the same way that the optical fibre F 1 is arranged on and attached to the outer surface of the walls of the equipment made of material M 1 .

11. Apparatus according to claim 7 or 8 , wherein the optical fibre Fi is placed on layer i only at certain points on the equipment.

12. The apparatus of claim 11 , wherein the optical fibre Fi is placed on layer i and around the circumference of the equipment at 3 or 4 different heights.

13. Apparatus according to claim 7 or 8 , which includes a layer of thermally conducting material M 2 in the region where the optical fibre F 1 is located that is surrounded on an outer surface by, and in thermal contact with, at least one optical fibre F 2 , said material M 2 and optical fibre F 2 being located between said optical fibre F 1 and layer i of thermally insulating material Mi.

14. Apparatus according to claim 13 wherein an outermost layer of material surrounding the equipment is layer i made of thermally insulating material Mi.