Union Carbide Chemicals & Plastics Technology Corporation

Dow Global Technolgoies LLC

Other

Univation Technologies, LLC

Ivan Jeremy Hartley

John Roberts Parrish

Paul Kevin Samples

Jeffrey Brian Drabish

Kiu H Lee

Guadalupe Garcia Leal

Mark L Nelson

Ping P Cai

William Albert Matthews

Lance Lyle Jacobsen

Thomas James McNeil

Rich John Stolz

Lonnie L Pinson

Marcel Schaefer

Darrell James Long

August Joseph Boldt

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.

In some embodiments, a method for determining initial conditions for a transition from an initial reaction to a target reaction to minimize (or substantially minimize) the amount of off-grade material produced during the transition, and optionally also process control variables for implementing the transition. Some embodiments also include the steps of setting the reaction conditions to determined initial conditions and then implementing the transition. In some embodiments, a product property that can cause production of more off-grade product during the transition than can any other of the properties is identified as a primary property, and process control variables for implementing the transition are determined so that the product produced during the transition goes off-grade due to the primary property, and due to each of at least one other product property, at the same or substantially the same time, and preferably also so that each non-primary property reaches a value compliant with the target specification set as late as possible but not later than the time the primary property reaches a value compliant with the target specification set.

Method for reducing off-grade product production during reaction transitions

A method for controlling resin properties during the production of polyolefins is provided. The method utilizes coordinated manipulation of reaction temperature in combination with a secondary process variable to control resin flow properties to rapidly respond to manufacturing upsets or specification changes to minimize off-grade or transition polymer material when moving from one polymer grade to another, or during a disturbance in a steady state production.

Control of resin properties

A process is disclosed for removing particulate product from a fluidized bed reactor to optimize, within the constraints of the product removal cycle, conservation of gas in which the product is entrained. Data are compiled on the time required for equalizing pressure between product discharge tanks, and these data are used to determine the optimum times for various valves to be open. Product movement steps and equalization steps can be performed simultaneously.

Reactor product discharge system

A method is provided to monitor, detect and correct local defluidization and channeling in fluidized-bed reactors for polymerization of olefin and/or diolefin polymers. The detection is preferably conducted by (i) continuously and/or intermittently comparing a signal which is a function of the currently measured fluidization bulk density with a signal which is a function of the time-averaged baselines of fluidized bulk density.

Method of detecting and correcting local defluidization and channeling in fluidized-bed reactors for polymerization

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

An improved method of bed temperature control is provided by the coordinated manipulation of the water flow rate in one or more heat exchangers and cycle gas flow rate to the reactor.

Method of fluidized bed temperature control

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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St. Albans, WV, United States of America

Ivan Jeremy Hartley