Optimized agitator system for production of polyolefin
AssigneeNOVA Chemicals (International) S.A.
InventorsYves Lacombe, Eric Clavelle, Stephen Salomons, Andrew Hawriuk, Stephen John Brown, Marion Walls
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Abstract
The various embodiments of the present invention relate to a polymerization reactor where the agitator mixing performance is optimized for use with a high activity catalyst and methods for developing the same.
Claims30
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 α-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.
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 α-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.
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 II” or “Zone III” region on each plot from step c,
- g. operate the CSTR reactor using the identified agitation speed.
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.
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.
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.
Dependencies are inferred from the claim text.