Exxonmobil Chemical Patents Inc.

Michael D Lucas

Ryan Winston Impelman

David Jack Sandell

Diwaker Singh

Handel D Bennett

Corrine L Brandl

Luis A Sotomayor

Aaron C McGinnis

Benjamin J Ohran

Stacy N Apugo

Christian T Lund

Rui Hoong Chong

David T Lakin

Keng-Hua Beh

Philip W Livanec

Anne Bernard-Brunel

Nathaniel B Guy

Gas phase polymerization processes include contacting an input stream comprising a monomer and an induced condensing agent in the presence of an inert gas with a catalyst in a fluidized bed reactor to produce a polymer, unreacted monomer, and an output gas; recycling a recycle stream of the unreacted monomer from the reactor to the input stream; venting at least a portion of the output gas from the reactor; and maintaining a partial pressure of the inert gas in the reactor above a reference inert gas pressure to decrease losses of the recycle stream with the vented output gas. The processes may include controlling the inert gas partial pressure to vary the total reactor pressure up to the maximum safe pressure, without causing carry-over of product polymer.

Optimized inert gas partial pressure in a gas phase polymerization process

In a process for producing an olefin polymer, at least one olefin monomer is polymerized in a polymerization reactor to produce a particulate polymer product containing hydrocarbon impurities including unreacted monomer and other Cto Chydrocarbons. The polymer product is contacted with a gas-containing stream in a stripping vessel under conditions effective to strip hydrocarbon impurities from the polymer product and produce a stripped particulate polymer product and a gaseous first effluent stream containing inert gas and hydrocarbon impurities. The stripped particulate polymer product is recovered and the atmosphere adjacent the stripped particulate polymer product is sensed with a photoionization detector configured to ionize Cto Chydrocarbons. The amount of the gas-containing stream supplied to the stripping vessel is then adjusted based upon such sensing.

Olefin polymerization processes

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.

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Houston, TX, United States of America

Michael D Lucas