Exxonmobil Chemical Patents Inc.

Henri Aime Lammens

Paul Jan Clymans

Philip H Cornelissen

Cindy Dewitte

Tom Van Nuland

Ivo T Goossens

Fausto F Ciancio

Roger L Claessens

Geert Vaes

Haiqing Peng

Jan Cyriel Donck

Christopher Kim Morgan

William J Zafian

Leo E Reynders

Arthur G Voepel

Jan J Naets

Frankie K R Verluyten

Martin J Decoster

Willy De Koster

Timothy S McCracken

Jefferson P Galliano

Philippe A P D'Hooghe

Controlling the shutdown of a polyethylene reactor system that includes a secondary compressor, a reactor, a high pressure let down valve (HPLDV), a high-pressure separator, and a high-pressure recycle gas system is provided. After a partial or complete shutdown of secondary compressor, HPLDV opens to a pre-set open position until the reactor pressure reduces to either a pre-set reduced pressure limit or a until the slope of the reactor gas density to reactor pressure exceeds 0.15. The HPLDV controls the pressure to a pressure set point.

Methods of controlling shutdown of reactor systems

The present disclosure provides processes for producing polyethylene resins. In at least one embodiment, a polyethylene has: a density of from about 0.91 g/cmto about 0.94 g/cm; a value of Mz of about 1,500,000 g/mol or greater; and a ratio of Mz to Mw of about 7 or greater. A process includes introducing a first feed stream having ethylene monomer and a first free radical initiator to a first inlet of a first reaction zone, where the first reaction zone has a first inlet temperature. The process further includes introducing a second feed stream having ethylene monomer and a second free radical initiator to a second inlet of a second reaction zone, where the second reaction zone has a second inlet temperature that is the same or different than the first inlet temperature.

Polyethylenes and processes for producing polyethylenes

This disclosure relates to systems and processes for cooling polymer product mixtures manufactured at high pressure. The processes of the invention involve cooling and then subsequently reducing the pressure of the product mixture from the reactor. In the systems of the invention, a product cooler is located downstream of the high pressure reactor and upstream of a high pressure let down valve.

High pressure polyethylene product cooling

Methods for producing polyethylene compositions having broader melt index ratio and narrower molecular weight distribution in high pressure multi-feed tubular reactors are provided. The methods are useful in multi-feed tubular reactors comprising three or more reaction zones. The first reaction zone or the first and second reaction zone having a peak temperature that is lower than standard peak temperatures for polymerization of ethylene monomer in a tubular reactor.

High pressure polyethylene tubular reactor processes for improved wire coating product

Systems and processes for rapidly depressurizing a reactor system are disclosed. The systems and processes are particularly useful in the high pressure polymerization of ethylene.

Rapid depressurization of a reactor system

Disclosed are an apparatus and a process for polymerizing ethylene under high pressure providing more than one injection point for one initiator injection pump.

Apparatus and process for high pressure polymerization of ethylene

Processes and systems for controlling modifier concentration in an ethylene polymerization reactor are disclosed.

Modifier control in high pressure polyethylene production

Systems and processes for controlling fouling in the manufacture of ethylene polymers and copolymers at high pressure. Disclosed is a high pressure polyethylene polymerization system comprising a reactor, a primary compressor, and a secondary compressor, the secondary compressor comprising: a) a first stage, wherein the first stage comprises at least two cylinders, and the discharge pipes of the at least two cylinders are fluidly connected by a first stage discharge cross-connect pipe; b) a second stage; c) an interstage; and d) a first cooler applied to the interstage piping starting at a location within 10 meters downstream of the first stage discharge cross-connect pipe.

Control of fouling in high pressure polyethylene manufacture

Both a system and method for cleaning a low pressure separation vessel of a high pressure polyethylene polymerization plant are provided. The system includes a polytetrafluoroethylene lining that covers the interior surfaces of the vessel, and a cover mounting assembly including an annular clamp for detachably mounting a cover over the vessel. The mounting assembly includes a clamp actuator for quickly securing and releasing the cover with respect to a top rim of the vessel. The vessel is drained of liquid polyethylene and allowed to cool to ambient temperature, thus creating a frozen 'skin' of polyethylene around the interior surfaces of the vessel. The clamp actuator releases the cover. The polyethylene skin is peeled off the interior sides the vessel and gathered up at the top to form a neck, thus peeling the polyethylene skin away from the polytetrafluoroethylene lining along with any degraded polymers or other impurities that have accumulated on the interior surfaces of the vessel.

Separation vessels for use in polymerization processes and methods for cleaning same

A system including a vessel with at least two fluid inlets and a fluid outlet wherein one fluid inlet is positioned higher in the vessel than the other fluid inlet is provided. The fluid inlets may be connected to a polymerization reactor and each fluid inlet may be configured to deliver fluid to the vessel from a different zone of the polymerization reactor. During shut-down of a polymerization reactor, reaction mixture is discharged to a separation system where polymer particles are removed from the mixture prior to being released into the atmosphere.

Fluid separation systems and methods

The invention relates to high pressure tubular reactor olefin polymerization plants having improved specific energy consumption. The plants may be newly constructed or made by de-bottlenecking an existing plant. The tube of the tubular reactor may have improved arrangements for cooling to increase conversion and optimized polymer-recycle gas separation arrangements using a jet pump for recycling unreacted monomer while permitting haze to be maintained. The improved cooling arrangements include a reduced pressure cooling zone forming the tail end of the tube and/or a shortened heating zone for the front feed and allowing more monomer to be fed as a side feed.

High pressure polymerization process

The invention provides a process and an apparatus for the high pressure polymerization of ethylene in which a jet pump is used to pump a fluid into a polymer/monomer product mixture leaving a bumped tubular reactor. The fluid may be recycled monomer or another fluid such as a modifier.

Process for the production of polyethylene and ethylene copolymers

The invention provides an apparatus and a process for the high pressure polymerization of ethylene, optionally with one or more comonomers, in which unreacted monomer is separated from the polymer in a separation system having at least first, second and third separation vessels and in which off gas from the second vessel is recombined back into the product mixture upstream of the first separation vessel, preferably using a jet pump.

Apparatus for the production of polyethylene and ethylene copolymers

Tubular reactor apparatus and processes are provided for improved polymerization including using chain transfer agents and multiple monomer feeds spaced lengthwise along the tubular reactor providing high conversions of monomer into polymer. The invention also relates to polymers made from such a tubular reactor apparatus and processes including those polymers having a low haze value, a density over 0.92 g/cmand/or having terminal carbonyl groups. The apparatus and methods uncouple or reduce the dependency between the monomer concentration and transfer agent concentration. The uncoupling in other embodiments may also be varied leading to multiple desirable effects.

Growing community of inventors

Antwerp, Belgium

Henri Aime Lammens