Exxonmobil Chemical Patents Inc.

Paul Jan Clymans

Henri Aime Lammens

Philip H Cornelissen

Cindy Dewitte

Tom Van Nuland

Ivo T Goossens

Danny Van Hoyweghen

Linda Maria Van Den Bossche

Joel Edward Schmieg

Rajesh Puthenkovilakom Raja

Scott C Solis

Anna C Claerbout

Arthur G Voepel

Fausto F Ciancio

Roger L Claessens

Geert Vaes

Willy De Koster

Daniel J Dobson

Jeffrey D Daily

Amit Kumar Ghosh

Ashley R Kropf

Jefferson P Galliano

Philippe A P D'Hooghe

Martin J Decoster

Philippe AP 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

A process for producing an ethylene copolymer, the process including: (a) contacting ethylene with at least one polar comonomer in the presence of at least one modifier and at least one free radical initiator in a tubular reactor under polymerization conditions including a pressure of from 225 to 270 MPa; (b) injecting the at least one free radical initiator into the reactor at a plurality of reaction zones spaced along the length of the reactor, wherein each reaction zone comprises an inlet and an outlet; (c) maintaining the temperature at the inlet of each reaction zone at 150&#xb0; C. or less, and the temperature at the outlet of each reaction zone is at least 177&#xb0; C.; (d) controlling the modifier flow at a rate of from 0.02 to 0.986 wt % of the copolymer; and (e) recovering the ethylene copolymer from the tubular reactor, is provided.

Process for producing ethylene copolymers

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

A process for producing ethylene polymer including compressing ethylene monomer in one or more compressors to a pressure from 1000 bar to 3000 bar; introducing the compressed ethylene monomer into one or more reactors; introducing a blend comprising an initiator and a modifier into the reactor where the ethylene monomer polymerizes forming a reaction mixture comprising unreacted ethylene monomer and ethylene polymer; and separating the ethylene polymer from the reaction mixture.

Process for manufacturing ethylene polymers and using modifiers

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

A method and pressure relief assembly for relieving a condition of over-pressure in a vessel are provided. In addition, a separator vessel suitable for operation in a process for polymerizing one or more olefins is provided.

Methods of relieving a condition of over-pressure in a vessel, pressure relief assemblies, and related separator vessels

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

A process for separating components of a reactor off gas is provided. A related reactor system is also provided. The reactor system may include a high pressure tubular reactor and/or an autoclave reactor and may be used for the production polyolefin polymers.

Reactor systems and processes related thereto

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

An ethylene polymerization system is provided with a quench system and that cools the product mixture entering the separation system with a reduced load on the first compressor of the system. The system includes first and second compressors, a high pressure reactor; a high pressure let down valve through which the product mixture from the high pressure reactor flows, and a separation system that separates gas from the product mixture. The quench system includes a pump having a suction inlet that receives all or substantially all of the low pressure flow of monomer from the first compressor. The system provides quenching of the product stream while allowing the first compressor to be operated at a discharge pressure lower than the suction pressure of the second compressor, thereby conserving energy.

Polyethylene manufacturing system and method

Processes for producing high pressure polyethylene and processes for increasing the crosslinkability of high pressure polyethylene are disclosed. The processes comprise controlling particular reaction parameters that have been found to promote crosslinkability in the resulting high pressure polyethylene. High pressure polyethylenes having improved crosslinkability are also disclosed.

Methods of improving crosslinkability of polyethylene polymer comprising polar comonomer and polymer compositions

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 relates to a process for the manufacture of ethylene polymers and copolymers in which ethylene is compressed in a primary compressor at a throughput of at least 55 tonnes/hour, mixed with recycled ethylene and further compressed in a two-stage reciprocating secondary compressor having at least 14 cylinders to a pressure of at least 2300 bar at a throughput of at least 120 tonnes/hour, heating at least a portion of that ethylene to a temperature of at least 95&#xb0; C. and introducing it into a tubular reactor of diameter at least 65 mm and a length of at least 1500 m, introducing initiator in at least three reaction zones to give a conversion of at least 28% and maintaining a pressure drop over the reactor to maintain a flow velocity of at least 6 m/s.

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Kapelle-op-den-Bos, Belgium

Paul Jan Clymans