Dow Global Technolgoies LLC

Other

Union Carbide Chemicals & Plastics Technology Corporation

Paul Kevin Samples

John Roberts Parrish

Ivan Jeremy Hartley

Jeffrey Brian Drabish

Mark L Nelson

Kiu H Lee

William Albert Matthews

Marcel Schaefer

Thomas J McNeil

Debbie D Rath

Darrell James Long

A method for improving the prediction of polymer properties and a system having improved polymer property prediction capabilities is provided. The method for improving the prediction of polymer properties comprises: (1) providing a polymer; (2) providing a prediction model; (3) utilizing said prediction model to define an average polymer property prediction value; (4) determining a feasible range; (5) measuring one or more properties of said polymer; (6) determining whether said one or measured polymer properties are within said feasible range: (7) validating said one or more measured polymer properties if said one or more measured polymer properties fall within the feasible range or invalidating said one or more measured polymer properties if said one or more measured polymer properties fall outside of the feasible range; (8) optionally updating said prediction model; (9) repeating said previous steps at least one or more times; and (10) thereby improving the prediction of polymer properties.

Method for improving the prediction of polymer properties

Embodiments of the invention provide a method of controlling a gas-phase polymerization process. The method includes determining a difference between a control variable of the polymerization process, such as the production rate, and the desired value of the control variable; adjusting or maintaining a first manipulated variable to at least partially compensate for the difference between the control variable and the desired value; and adjusting or maintaining a second manipulated variable to at least partially compensate for the effect of adjusting or maintaining the first manipulated variable. The first and second manipulated variables can include process variables such as the fluidized bed weight, the catalyst concentration, the concentration of one or more monomers, the flow of one or more comonomers, the ratio of one comonomer to another comonomer, the activator concentration, the ratio of an activator to selectivity control agent, the concentration of a chain transfer agent, and the retardant concentration.

Method of controlling a polymerization reactor

The present invention provides methods of controlling a gas-phase polymerization process. The method includes determining a difference between a control variable of the polymerization process, such as the production rate, and the desired value of the control variable; adjusting or maintaining a first manipulated variable to at least partially compensate for the difference between the control variable and the desired value; and adjusting or maintaining a second manipulated variable to at least partially compensate for the effect of adjusting or maintaining the first manipulated variable. The first and second manipulated variables can include process variables such as the fluidized bed weight, the catalyst concentration, the concentration of one or more monomers, the flow of one or more comonomers, the ratio of one comonomer to another comonomer, the activator concentration, the ratio of an activator to selectivity control agent, the concentration of a chain transfer agent, and the retardant concentration.

The invention provides a novel method of monitoring a process. The method also has the ability to take predetermined actions based on the monitored data. These actions avoid or mitigate process abnormalities or upsets that might impact product quality, production, and/or process efficiencies. The method includes the steps of: obtaining at least one input process variable; determining a comparative process value based on the at least one input process variable using a first method having a first time-based weighting function; determining an expected process value based on the at least one input process variable using a second method having a second time-based weighting function; determining a first deviation value based on the at least one input process variable or historical data; calculating a limit range having a maximum limit and a minimum limit using the expected process value and the first deviation value; and comparing the comparative process value to the limit range.

Process monitoring technique and related actions

In a polymerization reaction, an upset is anticipated and inhibited by monitoring at least one reaction condition and comparing it to the desired value or normal range for the condition as projected by a computer model for the variable or variables of the process. In a preferred variation, the process not only continuously adjusts the set point or range for an upset-significant variable such as temperature, but also utilizes the rate of change of such a variable as a harbinger of an upset.

Preventing upsets in polymerization reactors

A continuous process for the polymerization of one or more alpha-olefins in the gas phase in the presence of a chromium based catalyst, under polymerization conditions including the reaction temperature, the pressure, and the target oxygen to alpha-olefin molar ratio operating point required for desired resin properties.

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Scott Depot, WV, United States of America

Paul Kevin Samples