Method for production of polymer
Method for controlling a process for the production of a polymer by polymerization of a monomer and a comonomer. The process includes maintaining a substantially constant effective flow ratio (EFR), the effective flow ratio being defined as EFR=(Q como −L como )/(Q mono −L mono ), Q como and Q mono being, respectively, flow rates of comonomer and monomer to the reactor, L como and L mono being, respectively, losses of comonomer and monomer.
1. A method for controlling a process for the production of a polymer by polymerisation of a monomer and a comonomer which process comprises:
maintaining a substantially constant effective flow ratio (EFR), said effective flow ratio being defined as:
EFR=( Q como −L como )/( Q mono −L mono )
Q como and Q mono being, respectively, flow rates of comonomer and monomer to the reactor,
L como and L mono being, respectively, losses of comonomer and monomer.
2. A method according to claim 1 wherein Q mono and Q como are flow rates of fresh monomer and fresh comonomer to the reactor.
3. A method according to claim 1 wherein L mono and L como are losses of monomer and comonomer to purges.
4. A method for controlling a process for the production of a polymer by polymerisation of a monomer which process comprises:
maintaining a substantially constant effective flow ratio (EFR), said effective flow ratio being defined as:
EFR=( Q hyd −L hyd )/( Q mono −L mono )
Q hyd and Q mono being, respectively, flow rates of hydrogen and monomer to the reactor,
L hyd and L mono being, respectively, losses of hydrogen and monomer.
5. A method according to claim 4 wherein Qmono and Qhyd are flow rates of fresh monomer and fresh hydrogen to the reactor.
6. A method according to claim 4 wherein Lmono and Lhyd are losses of monomer and hydrogen to purges.
7. A method according to claim 1 which is applied under both steady-state and non-steady-state conditions.
8. A method according to claim 4 which is applied under both steady-state and non-steady-state conditions.
9. A method according to claim 1 which is a method for the start-up or transition of a process for the production of a polymer by polymerisation of a monomer and which process comprises during the start-up or transition:
I. maintaining a substantially constant effective flow ratio (EFR), said effective flow ratio being defined as:
EFR=( Q como −L como )/( Q mono −L mono )
Q como and Q mono being, respectively, flow rates of comonomer and monomer to the reactor,
L como and L mono being, respectively, losses of comonomer and monomer,
and optionally
II. maintaining a substantially constant effective flow ratio (EFR), said effective flow ratio being defined as:
EFR=( Q hyd −L hyd )/( Q mono −L mono )
Q hyd and Q mono being, respectively, flow rates of hydrogen and monomer to the reactor,
L hyd and L mono being, respectively, losses of hydrogen and monomer.
10. A method according to claim 4 which is a method for the start-up or transition of a process for the production of a polymer by polymerisation of a monomer and which process comprises during the start-up or transition:
I. maintaining a substantially constant effective flow ratio (EFR), said effective flow ratio being defined as:
EFR=( Q hyd −L hyd )/( Q mono −L mono )
Q hyd and Q mono being, respectively, flow rates of hydrogen and monomer to the reactor,
L hyd and L mono being, respectively, losses of hydrogen and monomer,
and optionally,
II. maintaining a substantially constant effective flow ratio (EFR), said effective flow ratio being defined as:
EFR=( Q como −L como )/( Q mono −L mono )
Q como and Q mono being, respectively, flow rates of comonomer and monomer to the reactor,
L como and L mono being, respectively, losses of comonomer and monomer.
11. A method according to claim 9 which comprises the above control during a start-up and subsequent steady-state operation.
12. A method according to claim 10 which comprises the above control during a start-up and subsequent steady-state operation.
13. A method according to claim 9 which comprises the above control during a transition and in preceding and subsequent steady-state operations.
14. A method according to claim 10 which comprises the above control during a transition and in preceding and subsequent steady-state operations.
15. A method according to claim 1 which is carried out in a gas phase fluidized-bed reactor.
16. A method according to claim 4 which is carried out in a gas phase fluidized-bed reactor.
17. A method according to claim 1 wherein the monomer is ethylene or propylene.
18. A method according to claim 4 wherein the monomer is ethylene or propylene.
19. A method according to claim 17 wherein the comonomer is an olefin having 4 to 8 carbon atoms, or ethylene where propylene is the monomer, or an olefin having 4 to 8 carbon atoms, or propylene where ethylene is the monomer.
20. A method according to claim 1 where the polymerisation process uses a Ziegler-Natta type catalyst, optionally in conjunction with a cocatalyst which is an organometallic compound of a metal from Groups I to III of the Periodic Classification of the Elements.
21. A method according to claim 4 where the polymerisation process uses a Ziegler-Natta type catalyst, optionally in conjunction with a cocatalyst which is an organometallic compound of a metal from Groups I to III of the Periodic Classification of the Elements.