Catalyst activator
The invention relates generally to a catalyst activator, and in particular to a catalyst activator for heat conditioning a catalyst, comprising: a) a vessel for containing a catalyst charge having an internal diameter of at least 1.2 meters and/or an internal volume of at least 5 m 3 ; b) a fluidization grid plate disposed in said vessel, said fluidization grid plate and having an upper major surface and a lower major surface; c) an array of generally conical depressions in said upper major surface that overlap by less than 17%; and d) an array of holes perforating said fluidization grid plate, said holes extending from at least some of said generally conical depressions through said lower surface.
1. A catalyst activator vessel, comprising:
a) a vessel for containing a catalyst charge having an internal diameter of at least 1.2 meters and/or an internal volume of at least 5 m 3 ;
b) a fluidisation grid plate disposed in said vessel, said fluidisation grid plate and having an upper major surface and a lower major surface;
c) an array of generally conical depressions in said upper major surface that overlap by less than 17%; and
d) an array of holes perforating said fluidisation grid plate, said holes extending from at least some of said generally conical depressions through said lower surface.
2. A catalyst activator according to claim 1 wherein the array of generally conical depressions are a regular triangular array.
3. A catalyst activator according to claim 1 wherein the array of generally conical depressions overlap by at least 15.5%, preferably in the range 15.6% to 16.5%.
4. A catalyst activator according to claim 1 wherein the vessel for containing a catalyst charge has an internal diameter of at least 1.2 meters, preferably at least 1.5 meters and/or up to 3 meters, and more preferably in the range 1.5 to 2.5 meters.
5. A catalyst activator according to claim 1 wherein the vessel for containing the catalyst charge is an inner vessel and is surrounded by an outer vessel, the gap between them forming a flue.
6. A catalyst activator according to claim 1 wherein holes extend through said lower surface from each generally conical depression in the upper surface, and thereby form an array of a fluid paths extending upwardly through each of said holes and said generally conical depressions.
7. A catalyst activator according to claim 1 wherein the pitch or spacing, being the distance between the centres of adjacent depressions, is between 2.5 and 5 cm, preferably in the range 3.5 to 4.5 cm.
8. A catalyst activator according to claim 1 wherein the nominal thickness of the fluidisation grid plate is in the range 35 to 100 mm, and more preferably from 40 mm and/or up to 65 mm.
9. A catalyst activator according to claim 1 wherein the depths of the generally conical depressions, as measured from the nominal upper surface, are less than 70% of the nominal plate thickness, preferably less than 60% and more preferably less than 50% of the nominal plate thickness.
10. A process for activating a polymerisation catalyst, which process uses a catalyst activator vessel according to claim 1 .
11. A process according to claim 10 comprising:
a) providing said catalyst activator vessel for heat conditioning the catalyst;
b) introducing into said vessel a catalyst charge;
c) introducing a fluidising medium into said vessel through the fluidisation grid plate in order to fluidise said catalyst charge, and
d) heating the fluidised bed of the catalyst to activate said catalyst.
12. A process according to claim 10 wherein the catalyst is a supported chromium oxide polymerisation catalyst.
13. A process according to claim 10 wherein heating the fluidised bed of the catalyst to activate said catalyst comprises heating the fluidised bed of the catalyst particles to a temperature in the range of 50 to 1000° C. and holding for 1 to 72 hours at said temperature.
14. A process according to claim 10 wherein the height of the fluidised bed of catalyst is at least twice the diameter of the fluidisation zone, such as at least three times the diameter, for example at least four times the diameter.
15. A process according to claim 10 wherein the array of generally conical depressions are a regular triangular array.
16. A process according to claim 10 wherein the array of generally conical depressions overlap by at least 15.5%, preferably in the range 15.6% to 16.5%.
17. A process according to claim 10 wherein the vessel for containing a catalyst charge has an internal diameter of at least 1.2 meters, preferably at least 1.5 meters and/or up to 3 meters, and more preferably in the range 1.5 to 2.5 meters.
18. A process according to claim 10 wherein the vessel for containing the catalyst charge is an inner vessel and is surrounded by an outer vessel, the gap between them forming a flue.
19. A process according to claim 10 wherein holes extend through said lower surface from each generally conical depression in the upper surface, and thereby form an array of a fluid paths extending upwardly through each of said holes and said generally conical depressions.
20. A process according to claim 10 wherein the pitch or spacing, being the distance between the centres of adjacent depressions, is between 2.5 and 5 cm, preferably in the range 3.5 to 4.5 cm.
21. A process according to claim 10 wherein the nominal thickness of the fluidisation grid plate is in the range 35 to 100 mm, and more preferably from 40 mm and/or up to 65 mm.
22. A process according to claim 10 wherein the depths of the generally conical depressions, as measured from the nominal upper surface, are less than 70% of the nominal plate thickness, preferably less than 60% and more preferably less than 50% of the nominal plate thickness.