Slurry phase polymerisation process
View Patent ↗A process comprising polymerizing an olefin monomer optionally together with an olefin comonomer in the presence of a polymerization catalyst in a diluent in a loop reactor which comprises at least 2 horizontal sections and at least 2 vertical sections to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the Froude number in at least 20% of the length of the vertical sections of the reactor loop is less than 85% of the Froude number in at least 20% of the length of the horizontal sections of the loop is disclosed.
1. A process comprising polymerising an olefin monomer optionally together with an olefin comonomer in the presence of a polymerization catalyst in a diluent in a loop reactor which comprises at least 2 horizontal sections and at least 2 vertical sections to produce a slurry comprising solid particulate olefin polymer and the diluent wherein the Froude number in at least 20% of the length of the vertical sections of the reactor loop is less than 85% of the Froude number in at least 20% of the length of the horizontal sections of the loop.
2. A process claimed in claim 1 wherein the average Froude number in the loop reactor is maintained at or below 20.
3. A process as claimed in claim 2 wherein the average Froude number in the loop reactor is maintained in the range 10 to 3.
4. A process as claimed in claim 1 wherein the Froude number in the vertical sections of the loop reactor with upward circulation is maintained at between 30 and 85% of the minimum Froude number used in the horizontal sections.
5. A process as claimed in claim 1 wherein the Froude number in the vertical sections of the loop reactor with downward circulation is maintained at between 15 to 70% of the minimum Froude number used in the horizontal sections.
6. A process as claimed in claim 1 wherein the Froude number in the horizontal sections is maintained below 30.
7. A process as. claimed in claim 1 wherein the Froude number in the vertical sections is maintained below 20.
8. A process as claimed in claim 1 wherein the horizontal sections of the loop reactor consist of no more than 20% of the total reactor length.
9. A process as claimed in claim 1 wherein the total loop pressure drops by less than 1.3 bar.
10. A process as claimed in claim 1 wherein the reactor size is over 50 m 3 .
11. A process as claimed in claim 1 wherein the average internal diameter of the loop reactor is over 300 millimeters.
12. A process as claimed in claim 11 wherein the average internal diameter of the loop reactor is in the range 600 to 750 millimeters.
13. A process as claimed in claim 1 wherein the ratio of the reactor length to the average internal diameter of the loop reactor is less than 500.
14. A loop reactor of a continuous tubular construction comprising at least two horizontal sections and at least two vertical sections wherein the internal cross sectional area of at least 20% of the vertical sections is at least 5% greater than the largest internal cross sectional area that covers at least 20% of the horizontal sections, wherein the average internal diameter of the horizontal sections is in the range 500-700 millimeters and the average internal diameter of the vertical section is in the range 600-900 millimeters.
15. A process as claimed in claim 13 wherein the ratio of the reactor length to the average internal diameter of the loop reactor is less than 250.