Exxonmobil Chemical Patents Inc.

Keith W Trapp

Zerong Lin

Douglas J Picou

Kelly M Forcht

Asha C Quant

Ariana L Poindexter

Maxwell T Mcgee

John L Begue

Christopher Garland Bauch

Kevin Wayne Lawson

James Austin Kendrick

Scott Thomas Roger

Todd S Edwards

Edward F Smith

Blu E Englehorn

A method for regulating use of stored diluent in a polymerization process so as to maximize use of diluent recycled diluent recovered from the process, and so minimize use of stored diluent, is disclosed. Also disclosed is apparatus, particularly as an arrangement of controllers and valves for handling the flow of diluent through the process that can be used to implement the disclosed process.

Recycle diluent control and optimization for slurry loop polyethylene reactors

A process for maintaining an optimum polymerization process in a continuous loop polymerization reactor by driving a catalyst feed range set-point around a bad catalyst set-point range using a bad catalyst feed rate program to vary the catalyst feed rate for differing periods of time between previously determined good catalyst feed rates.

Slurry loop reactor bad catalyst range control

A process and system for maintaining optimum polymerization production in a loop polymerization reactor by continuously and periodically obtaining polymerization results, such as melt index (MI), production rate and ash content of the polymer produced, determining whether each of the results is within desired ranges, storing and averaging recently obtained results in a database within a reaction rate controller program, and when one of the results is out of the desired range modifying at least one reaction parameter set-point such as monomer concentration, catalyst feed rate and reactor temperature to drive any out-of-range polymerization result(s) toward the desired range for that result.

Slurry loop reactor polymerization rate and quality controller

A method for minimizing the amount of catalyst inactivating agent that is present in a liquid fraction recovered from a slurry-based polymer production process, the liquid fraction comprising diluent used in the polymer production process, is disclosed. The method includes steps for controlling the pressure over the liquid fraction collected during diluent recovery so as to minimize the concentration of catalyst inactivating agent that is retained in the recovered liquid fraction. Embodiments of apparatus suitable for conducting the disclosed method are also provided.

Vent gas purge optimizer for slurry loop polyethylene reactors

Processes and apparatus for preparing bimodal polymers are provided. In some embodiments, processes include introducing a monomer, a first diluent, a catalyst, hydrogen, at a first hydrogen concentration, and optional comonomer, to a first loop reactor to produce, under polymerization conditions, a first slurry of polymer solids. Processes may also include continuously discharging the first slurry of polymer solids from the loop reactor as a first polymerization effluent to a first flash tank; separating the first polymerization effluent in the first flash tank to provide a first concentrated polymer slurry with significantly lower hydrogen concentration; and transferring the first concentrated polymer slurry from the flash tank to a re-slurry mixer. Processes may further include introducing a re-slurry mixer diluent to the first concentrated polymer slurry to form a second concentrated polymer slurry in the re-slurry mixer that can be pumped to a second slurry loop reactor.

Processes and apparatus for bimodal slurry polymerization

A process for reducing the level of hydrogen in certain polymerization effluent and recycle streams containing unreacted propylene monomers and hydrogen by contacting the streams with a hydrogenation catalyst so as to convert at least part of the propylene to the corresponding alkane. The process is particularly applicable to the effluent from a slurry polymerization reactor which has been used to produce a polypropylene homopolymer or copolymer having a first molecular weight and at least part of the effluent is to be supplied to a slurry polymerization reactor to produce a polypropylene homopolymer or copolymer having a second, higher molecular weight.

Growing community of inventors

Kingwood, TX, United States of America

Keith W Trapp