Patent ID: 7838605

Claim:
A method of olefin polymerization, the method comprising: (a) determining a flow ratio to a polymerization reactor, FR 1 , of a comonomer flow rate to a monomer flow rate provided to the reactor; determining the concentration ratio, GR 1 , of the concentration of the comonomer to the concentration of the monomer in a recycle stream of the reactor, (b) obtaining a leading indicator function, LI, defined by: LI = FR 1 GR 1 = ( β ) ⁢ ( FR 2 ) + ( 1 - β ) ⁢ ( FR 3 ) GR 1 ( 1 ⁢ a ) where GR 1 is the present value of the comonomer/ethylene concentration ratio at time T in the reactor, as determined by analysis of the recycle stream; where FR 1 is the present value of the flow ratio of the comonomer flow rate to monomer flow rate into the reactor, expressed as an exponentially weighted moving average (EWMA) at time T; where FR 2 is the instantaneous flow ratio td minutes prior to time T; where FR 3 is an EWMA using the comonomer residence time td minutes prior to time T−1; where td is the delay time for recycle gas analysis; where β=1−exp(−T/(comonomer residence time) =1−exp(−-Δt/τ); where Δt =the time step chosen to update the LI calculation; where τ=the residence time in the reactor of the comonomer that is used to calculate the LI with the proviso that the comonomer dissolved in the polymerized olefin is included in said comonomer used to calculate the LI; (c) comparing the LI to a target value; (d) adjusting at least one reactor parameter in response to a deviation between the LI and the target value; and (e) controlling a polymer product property.