Exxonmobil Chemical Patents Inc.

Univation Technologies, LLC

Mobil Oil Corporation

David Jack Sandell

Fred David Ehrman

Marjorie E King

Ryan Winston Impelman

Marc L DeChellis

Handel D Bennett

Michael G Tribo

Aaron C McGinnis

Michael D Lucas

David H Anderson

Giyarpuram N Prasad

Benjamin J Ohran

Richard J Stolz

Richard M Coon

Bohumil Vaclav Kral

Kirk D Carver

Jason R Fischer

Gerardo Corona

David T Lakin

Marc L De Chellis

A process for producing an olefin polymer employs a gas phase polymerization reactor having a product discharge system comprising first and second pairs of lock hoppers, wherein each pair comprises an upstream lock hopper connected by valve means to the reactor and a downstream lock hopper connected by valve means to the upstream lock hopper and by further valve means to a product recovery system, and wherein a first cross-tie is provided between the upstream lock hoppers of the first and second pairs of lock hoppers and a second cross-tie is provided between the downstream lock hoppers of the first and second pairs of lock hoppers. Operation of the second cross-tie during product removal cycles is controlled in accordance with reactor pressure.

Olefin polymerization processes

A method for the removal of unreacted olefin monomer(s) from polyolefin product particles of an olefin polymerization reaction, the method including: contacting the polyolefin product particles with a countercurrent flow of a purge gas in a purge vessel under conditions allowing diffusion of unreacted monomer and other gaseous substances from the polyolefin product particles into the countercurrent flow of the purge gas to produce purged particles; wherein the velocity of the purge gas exceeds 50% of the calculated minimum fluidization velocity of the polyolefin product particles in the purge vessel (U), is provided.

Removal of unreacted monomers and other materials from polyolefin product particles

In a process for producing an olefin polymer, an olefin monomer is polymerized to produce a particulate polymer product containing unreacted monomer. The polymer product is contacted with an inert gas to strip hydrocarbon impurities therefrom and produce a stripped polymer product and a gaseous first effluent stream containing inert gas and hydrocarbons. The stripped polymer product is recovered and the first effluent stream is compressed and cooled to condense hydrocarbons contained therein and produce a gaseous second effluent stream. Part of the second effluent stream is contacted with a first membrane separator to produce a first hydrocarbon-enriched permeate stream and a first hydrocarbon-depleted residue stream. The first residue stream is contacted with a second membrane separator to produce a second hydrocarbon-enriched permeate stream and a second hydrocarbon-depleted residue stream. The second permeate stream and an oxidizing agent are supplied to a flameless thermal oxidation unit.

In a gas phase fluidized bed polymerization process for the production of polyolefin polymers, such as polyethylene polymers or polypropylene polymers, loss of ethylene or propylene accompanying inert gas purging is reduced by passing an ethylene- or propylene-containing purge stream through a vent column to contact a hydrocarbon liquid flowing through the vent column contercurrent to the purge stream whereby unreacted ethylene or propylene in the purge stream portion is dissolved in the hydrocarbon liquid to produce an ethylene- or propylene-enriched liquid stream and an ethylene- or propylene-depleted gaseous stream. The ethylene- or propylene-enriched liquid stream is then recycled to the fluidized bed reactor, while at least part of the ethylene- or propylene-depleted gaseous stream is purged.

Polymerization processes

A process including contacting one or more monomers, at least one catalyst system, and a condensing agent including a majority of 2,2-dimethylpropane under polymerizable conditions to produce a polyolefin polymer is provided.

Polymerization process

Disclosed herein are methods and systems for purging a polymer product of volatiles. The methods and systems are particularly useful in the purging of a polyethylene polymer product produced in a fluidized bed reactor.

Control methods and systems for polymer product purge

Embodiments of our invention relate generally to methods of monitoring and controlling polymerization reactions including reactions producing multimodal polymer products using multiple catalysts in a single reactor. Embodiments of the invention provide methods of rapidly monitoring and controlling polymerization reactions without the need to sample and test the polymer properties. The method uses reactor control data and material inventory data in a mathematical leading indicator function to control the reactor conditions, and thereby the products produced under those conditions.

Polymerization monitoring and method of selecting leading indicators

Polymerization monitoring and control using improved leading indicators

One exemplary method for message suppression comprises: providing first and second rules, each having one or more preconditions and a conclusion, wherein the first rule also has a suppressed-by attribute and at least one of the second preconditions is suppressing; evaluating the one or more first and second preconditions; identifying the first rule as true or false; displaying the message of the second rule if all of the second preconditions are met; identifying the first rule as suppressed if the second rule is named in the suppressed-by attribute; and inhibiting the message display of the suppressed rule or routing the message to second display. The system can comprise: a database containing knowledge of the production unit; a user interface, and at least one precondition, a suppressed by attribute, and one or more rules each having a conclusion and at least one suppressing precondition; an inference engine; and a display.

Monitoring polyethylene polymerization system utilizing the method for message suppression in rule based expert system

A system for controlling temperature of a polymerization process includes a primary reactor system having a polymerization reactor and a recycle gas line which includes a heat exchanger, a primary temperature controller which continuously measures temperature within the reactor and provides a coolant adjust signal, a secondary cooling system which circulates a mixture of fresh and recirculated coolant through the heat exchanger and a secondary temperature controller which continuously measures the temperature of the mixed coolant and adjusts the proportion of mixed coolant to fresh coolant based on the coolant adjust signal and the temperature of the mixed coolant.

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Beaumont, TX, United States of America

David Jack Sandell