CLAIMS

1. A method for fluid phase polymerizing a polyethylene polymer or copolymer comprising reacting a polymerization catalyst having an apparent activity greater than 20,000 m3/kmole/sec with ethylene, optionally a C3-12 a-olefin, and hydrogen in an agitated reactor wherein the reactor HUT/BT is greater than 7 and the reactor circulation ratio is between about 7 and about 2000.

2. The method of claim 1 , wherein 1/the bulk Damkoehler number is between about 6 and about 150.

3. The method of claim 1, wherein the catalyst is a single site catalyst.

4. The method of claim 1, wherein the catalyst comprises a bulky ligand single site catalyst of the formula:

(L)„— M— (Y)p

wherein M is selected from Ti, Zr and Hf; L is a monoanionic ligand independently selected from cyclopentadienyl-type ligands, and a bulky heteroatom ligand containing not less than five atoms in total (typically of which at least 20%, or, for example, at least 25%

numerically are carbon atoms) and further containing at least one heteroatom selected from boron, nitrogen, oxygen, phosphorus, sulfur and silicon, said bulky heteroatom ligand being sigma or pi-bonded to M, Y is independently selected from activatable ligands; n may be from 1 to 3; and p may be from 1 to 3, provided that the sum of n+p equals the valence state of M, and further provided that two L ligands may be bridged for example by a silyl radical or a Ci-4 alkyl radical, or a mixture thereof.

5. The method of claim 1, wherein the a-olefin is present and is selected from propene, butene, hexene, and octene.

6. The method of claim 1, wherein the reactor circulation ratio is from about 7 to about 1000.

7. The method of claim 1, wherein the reactor HUT/BT is from about 7 to about 100.

8. The method of claim 1 , wherein the power/unit volume is less than 300 kW/m3.

9. The method of claim 1 , wherein the reactor circulation ratio is from about 7 to about 500 and reactor HUT/BT is from about 7 to about 20 and 1/bulk Damkoehler number is from about 6 to about 150.

10. The method of claim 1, wherein the reactor is a single reactor.

11. The method of claim 1, wherein the reactor is a dual reactor.

12. The method of claim 1, wherein the reactor is an agitated reactor.

13. The method of claim 1, wherein the reactor is an agitated reactor selected from stirred tank, loop reactor static mixer, and static mixer in a loop.

14. The method of claim 1, wherein the reactor temperature is greater than about 110°C.

15. A method for fluid phase polymerizing a polyethylene polymer or copolymer comprising reacting a polymerization catalyst having an apparent activity greater than

20,000 m3/kmole/sec with ethylene, optionally a C3-12 a-olefin, and hydrogen in an agitated reactor wherein the reactor HUT/BT is greater than 4, reactor circulation ratio is between about 7 and about 2000, and the power/unit volume is less than 35 kW/m3.

16. The method of claim 15, wherein 1/the bulk Damkoehler number is between about 6 and about 150.

17. The method of claim 15, wherein the catalyst is a single site catalyst.

18. The method of claim 15, wherein the catalyst comprises a bulky ligand single site catalyst of the formula:

(L)„— M— (Y)p

wherein M is selected from Ti, Zr and Hf; L is a monoanionic ligand independently selected from cyclopentadienyl-type ligands, and a bulky heteroatom ligand containing not less than five atoms in total (typically of which at least 20%, or, for example, at least 25%

numerically are carbon atoms) and further containing at least one heteroatom selected from boron, nitrogen, oxygen, phosphorus, sulfur and silicon, said bulky heteroatom ligand being sigma or pi-bonded to M, Y is independently selected from activatable ligands; n may be from 1 to 3; and p may be from 1 to 3, provided that the sum of n+p equals the valence state of M, and further provided that two L ligands may be bridged for example by a silyl radical or a Ci-4 alkyl radical, or a mixture thereof.

19. The method of claim 15, wherein the a-olefin is present and is selected from propene, butene, hexene, and octene.

20. The method of claim 15, wherein the reactor circulation ratio is from about 7 to about 1000.

21. The method of claim 15, wherein the reactor HUT/BT is from about 7 to about 100.

22. The method of claim 15, wherein the power/unit volume is less than 30 kW/m3. 23. The method of claim 15, wherein the reactor circulation ratio is from about 7 to about 500 and reactor HUT/BT is from about 4 to about 7 and 1/bulk Damkoehler number is from about 3 to about 50.

24. The method of claim 15, wherein the reactor is an agitated reactor.

25. The method of claim 15, wherein the reactor is an agitated reactor selected from stirred tank, loop reactor static mixer, and static mixer in a loop.

26. The method of claim 15, wherein the reactor temperature is greater than about 110°C.

27. A method for selecting agitator speed to reduce the cost of operating a CSTR comprising:

a. measuring the HUT/BT and circulation ratio of the reactor,

b. measuring the mixing performance indicator of the final polymer product, c. plotting the HUT/BT and circulation ratio vs the performance indicator, d. varying the agitator speed or HUT to get a new HUT/BT and circulation ratio,

e. repeating steps a-d until the plotted line of step c shows a roughly horizontal lines (asymptote), and

f. lowering the agitation rate of the reactor for commercial polyethylene polymerization so the mixing performance falls within a "Zone Π" or "Zone III" region on each plot from step c,

g. operate the CSTR reactor using the identified agitation speed.

28. A method for selecting agitator speed to increase capacity in a CSTR comprising: a. measuring the HUT/BT and circulation ratio of the reactor,

b. measuring the mixing performance indicator of the final polymer product, c. plotting the HUT/BT and circulation ratio vs the performance indicator, d. varying the agitator speed or HUT to get a new HUT/BT and circulation ratio,

e. repeating steps a-d until the plotted line of step c shows a roughly horizontal lines (asymptote), and

f. lowering the agitation rate of the reactor for commercial polyethylene polymerization so the mixing performance falls within a "Zone II" or "Zone III" region on each plot from step c,

g. operate the CSTR reactor using the identified agitation speed.

29. A method for transferring reaction conditions for an ethylene polymerization process from one plant to another comprising:

a. measuring the HUT/BT and circulation ratio of a reactor system for the desired product,

b. setting up the reaction conditions in the new reactor to match the HUT/BT and meet or exceed the circulation ratio measured in step a.

30. A method to improve the range of products that can be produced in a reactor system comprising:

a) determine desired product characteristics and process conditions by modeling,

b. calculate or determine the HUT/BT and circulation ratio of the reactor system,

c. iteratively varying the reactor process conditions to get a new HUT/BT and circulation ratio in the model,

d. select the operating conditions that provide the desired determined product characteristics, and

e. run the process.