Polyolefin process monitoring and control

A method of controlling an olefin polymerization reactor system, the method comprising:

• a) selecting n input variables I1, I2, I3, . . . In, each input variable corresponding to a process condition for an olefin polymerization process;
• b) identifying m response variables, R1, R2, R3, . . . Rm, each response variable corresponding to a measurable polymer property, wherein two of the m response variables are molecular weight distribution (MWD) and short chain branching (SCB);
• c) adjusting one of more of the n input variables Ii to In in a plurality of polymerization reactions using the olefin polymerization reactor system, to provide a plurality of olefin polymers and measuring each of the m response variables R1 to Rm as a function of the input variables for each olefin polymer;
• d) analyzing the change in each of the response variables R1 to Rm as a function of the input variables I1 to In to determine the coefficients C0 and Cu (for u=1 to n) according to the following general equation for each response variable R1 to Rm:
• R1-m=C0+Σu=1u=nCu(Iu)
• e) calculating a Response Surface Model (RSM) using general equations for each response variable R1 to Rm (R1-m) determined in step d) to correlate any combination of the n input variables I1 to In with one or more of m response variables R1 to Rm;
• f) applying n selected input variables Is1, Is2, Is3. . . Isn to the calculated Response Surface Model (RSM) to predict one or more of m target response variables, Rt1, Rt2, Rt3, . . . Rtm, each target response variable corresponding to a measurable polymer property;
• and
• g) using the n selected input variables Is1 to Isn to operate the olefin polymerization reactor system and provide a polyolefin product.