# US 10,865,261 B2 · Methods of monitoring and controlling the melt index of a polyolefin product during production > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,865,261 B2 - Document ID: US10865261B2 - Status: Granted - Kind: B2 - Application number: 16/409,952 - Filed: 2019-05-13 - Published: 2019-08-29 - Granted: 2020-12-15 - Earliest claimed: 2014-11-25 - Assignees: Univation Technologies, LLC - Applicants: Univation Technologies, LLC - Inventors: Bruce J. Savatsky; Daniel N. Thomas, Jr.; Timothy R. Lynn - Web page: https://patentgrep.com/patent/US10865261B2 ## CPC - C08F 210/16: Copolymers of ethene with alpha-alkenes, e.g. EP rubbers - B01J 8/1809: {Controlling processes} - B01J 8/1827: {the fluidising gas being a reactant} - B01J 8/1836: {Heating and cooling the reactor (B01J8/42 takes precedence)} - G05B 17/00: Systems involving the use of models or simulators of said systems (G05B13/00, G05B15/00, G05B19/00 take precedence) - B01J 2208/00061: of the reactants - B01J 2208/00274: involving reactant vapours - B01J 2208/00539: Pressure - B01J 2208/00548: Flow - B01J 2208/00628: Controlling the composition of the reactive mixture - B01J 2208/00663: Concentration - B01J 2208/00725: Mathematical modelling - B01J 2208/00991: Disengagement zone in fluidised-bed reactors - C08F 4/65922: {containing at least two cyclopentadienyl rings, fused or not} - C08F 2400/02: Control or adjustment of polymerization parameters - C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS - B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) ## Abstract Methods for producing polyolefin polymers may use a predictive melt index regression to estimate the melt index of the polyolefin during production based on the composition of the gas phase and, optionally, the concentration of catalyst in the reactor or reactor operating conditions. Such predictive melt index regression may include multiple terms to account for concentration of ICA in the reactor, optionally concentration of hydrogen in the reactor, optionally concentration of comonomer in the reactor, optionally the catalyst composition, and optionally reactor operating conditions. One or more terms may independently be represented by a smoothing function that incorporates a time constant. ## Claims ### Claim 1 A method comprising: contacting in a fluidized bed gas phase reactor an olefin monomer with a catalyst system in the presence of an induced condensing agent (ICA) and optionally hydrogen to produce a polyolefin having a melt index; monitoring a reactor ICA concentration, optionally a reactor hydrogen concentration, and the melt index of the polyolefin; calculating a predictive melt index regression based on an effect of the concentration of the ICA in the reactor and optionally an effect of the hydrogen in the reactor on the melt index of the polyolefin, wherein at least one term of the predictive melt index regression associated with the concentration of the ICA or the concentration of the hydrogen is independently represented by a smoothing function that incorporates a time constant; calculating a predicted melt index using the predictive melt index regression based on a change in the reactor ICA concentration; and adjusting the reactor ICA concentration based on the predicted melt flow index to maintain the melt index within or move the melt index to within a melt index threshold range. ### Claim 2 (depends on 1) The method of claim 1, wherein terms of the predictive melt index regression associated with the concentration of the ICA and the concentration of the hydrogen are each independently represented by a smoothing function that incorporates a time constant. ### Claim 3 (depends on 1) The method of claim 1, further comprising: contacting in the fluidized bed gas phase reactor the olefin monomer and at least one comonomer with the catalyst system in the presence the ICA and optionally hydrogen to produce the polyolefin; and monitoring a mole percent of total reactor gas ratio of the olefin monomer and the at least one comonomer (olefinmol:comonomermol); calculating the predictive melt index regression further based on an effect of the olefinmol:comonomermol on the melt index of the polyolefin where a term of the predictive melt index regression associated with the olefinmol:comonomermol is a smoothing function that incorporates a time constant. ### Claim 4 (depends on 1) The method of claim 1, wherein the catalyst system includes a high molecular weight (HMW) catalyst and a low molecular weight (LMW) catalyst, wherein the method further includes: monitoring a mole ratio of the HMW catalyst and the LMW catalyst (HMWmol:LMWmol) in the reactor, and calculating the predictive melt index regression further based on an effect of the HMWmol:LMWmol on the melt index of the polyolefin. ### Claim 5 (depends on 1) The method of claim 1, further comprising adjusting the mole ratio of the HMW catalyst and the LMW catalyst (HMWmol:LMWmol) in the reactor based on the predicted melt index. ### Claim 6 (depends on 1) The method of claim 1, wherein the time constant associated with the concentration of the ICA is about 50 minutes or greater. ### Claim 7 (depends on 1) The method of claim 1, wherein the time constant associated with the concentration of the ICA is about 100 minutes to about 300 minutes. ### Claim 8 (depends on 1) The method of claim 1, wherein the smoothing function is an exponential smoothing function. ### Claim 9 (depends on 1) The method of claim 1, wherein the predictive melt index regression is an exponential function. ### Claim 10 (depends on 1) The method of claim 1, wherein the concentration of the ICA is represented by a partial pressure of the ICA (ICAPP). ### Claim 11 (depends on 1) The method of claim 1, wherein the concentration of the hydrogen is represented by a mole percent of total reactor gas ratio of the hydrogen to the olefin monomer (H2mol:olefinmol). ### Claim 12 (depends on 1) The method of claim 1, wherein the concentration of the comonomer is represented by a mole percent of total reactor gas ratio of the olefin monomer and the at least one comonomer (olefinmol:comonomermol). ### Claim 13 (depends on 1) The method of claim 1, wherein the predictive melt index regression includes at least one additional term associated with reactor temperature or polymer residence time.