Patent ID: 8354481

Claim:
A method of controlling a gas-phase polymerization process, comprising: (a) continuously, periodically or intermittently determining a difference between an actual or estimated value of a control variable and a desired value of the control variable; (b) adjusting or maintaining at least a first manipulated variable to at least partially compensate for the difference between the actual or estimated value of control variable and the desired value; and (c) adjusting or maintaining a second manipulated variable to at least partially compensate for the effect of adjusting or maintaining the first manipulated variable; wherein the first and second manipulated variables are selected from the group of process conditions consisting of a weight of fluidized bed, a concentration of one or more monomers, a flow of one or more comonomers, a ratio of a first comonomer to a second comonomer, an first activator concentration, a ratio of a second activator to selectivity control agent, a concentration of a chain transfer agent, and a retardant concentration.