EP-4577580-B1 - HIGH-PRESSURE POLYMERIZATION PROCESS WITH CONTROLLED GAS VELOCITY

Inventors

• KHAYRULLIN, Danir
• MOHRBUTTER, Juergen
• WOLF, CHRISTOPH
• FINETTE, ANDRE-ARMAND
• DEUERLING, MICHAEL
• WOLFRAM, Sven

Dates

Publication Date

20260506

Application Date

20231031

Claims (15)

1. Process for polymerizing or copolymerizing one or more ethylenically unsaturated monomers at temperatures from 100 to 350 °C and pressures in the range from 110 to 500 MPa, wherein a gaseous reaction mixture is compressed in a hyper compressor (100) comprising - a first compressing stage (1) comprising at least two cylinders being connected to a first stage discharge collection and distribution system (2) via a first stage discharge pipe system (3); - a second compressing stage (2) comprising at least two cylinders being connected to a second stage suction collection and distribution system (6) via a second stage suction pipe system (7) and to a second stage discharge collection and distribution system (8) via a second stage discharge pipe system (9); - a heat exchanger (4) arranged between the first and second compressing stage (1, 2); wherein the reaction mixture is provided to each compressing stage through a suction pipe system and the compressed reaction mixture is discharged from the compressing stage through a discharge pipe system; wherein - the velocity of the gaseous reaction mixture in the first stage discharge pipe system (3) is from 0.8 m/s to 2.5 m/s; and/or - the velocity of the gaseous reaction mixture in the first stage discharge collection and distribution system (2) is from 2 m/s to 4 m/s; and/or - the velocity of the gaseous reaction mixture in the second stage discharge pipe system (9) is from 0.8 m/s to 3.5 m/s; and/or - the velocity of the gaseous reaction mixture in the second stage discharge collection and distribution system (8) is from 4 m/s to 9 m/s.
2. The process of claim 1, wherein the collection and distribution systems are selected from the group consisting of cross-connect pipe, cross-connect block and high-pressure manifold.
3. The process of any of the forgoing claims, wherein the velocity of the gaseous reaction mixture in the first stage discharge pipe system (3) is less than 1.7 m/s.
4. The process of any of the forgoing claims, wherein the velocity of the gas reaction mixture in first stage discharge collection and distribution system (2) is less than 3.5 m/s.
5. The process of any of the forgoing claims, wherein the velocity of the gaseous reaction mixture in the second stage discharge pipe system (9) is less than 2.5 m/s.
6. The process of any of the forgoing claims, wherein the velocity of the gaseous reaction mixture in the second stage discharge collection and distribution system (8) is less than 7 m/s.
7. The process of any of the forgoing claims, wherein the first compressing stage (1) is connected with a first stage suction collection and distribution system (11) via a first stage suction pipe system (12) and wherein the velocity of the gaseous reaction mixture in the first stage suction pipe system (12) is preferably between 0.5 m/s and 3 m/s, in particular less than 1.5 and/or the velocity of the gaseous reaction mixture in the first stage suction collection and distribution system (11) is between 3 m/s and 7 m/s, in particular less than 6 m/s.
8. The process of any of the forgoing claims, wherein the velocity of the gaseous reaction mixture in the second stage suction pipe system (7) is preferably from 0.5 m/s to 2.5 m/s, in particular less than 1.5 and/or the velocity of the gaseous reaction mixture in the second stage suction collection and distribution system (6) is from 2 m/s to 3.5 m/s, in particular less than 3 m/s.
9. The process of any of the forgoing claims, wherein the gaseous reaction mixture is conveyed from the first stage discharge collection and distribution system (2) through one or more mixing block (16) before entering the heat exchanger (4).
10. The process of any of the forgoing claims, wherein the gaseous reaction mixture is conveyed from the second stage discharge collection and distribution system (8) through a mixing block before being conveyed to a polymerization reactor (15).
11. The process of any of the forgoing claims, wherein the gaseous reaction mixture is conveyed from the heat exchanger (4) to one or more mixing blocks (16) before entering the second stage suction collection and distribution system (6).
12. The process of any of the forgoing claims, wherein the compressor system further comprises a pipe (13) for providing the reaction mixture to the first stage suction collection and distribution system (11), wherein the gas velocity in said pipe is preferably from 3 to 7 m/s, preferably less than 6 m/s.
13. The process of any of the forgoing claims, wherein the compressor system further comprises a pipe (14) for discharging the reaction mixture from the second stage collection and distribution system (8), wherein the gas velocity in said pipe is preferably from 10 to 16 m/s.
14. The process of any of the forgoing claims, wherein the reaction is compressed in a primary compressor (10) before entering the hyper compressor.
15. The process of any of the forgoing claims, wherein the velocity of the gaseous reaction mixture in the second stage discharge pipe system is higher than the velocity of the gaseous reaction mixture in the first stage discharge pipe system.

Description

FIELD OF THE DISCLOSURE The present disclosure refers to a process for the polymerization or copolymerization of one or more ethylenically unsaturated monomers with a controlled gas velocity of the gaseous reaction as well as a high-pressure polymerization apparatus for carrying out the process of the present disclosure. BACKGROUND OF THE DISCLOSURE Polymers play an essential and ubiquitous role in everyday life. One way to obtain polymers is by high-pressure polymerization which turns relatively low-cost olefin monomers such as ethylene, optionally in combination with one or more comonomers, into valuable polyolefin products. Polyethylene, being the most widely used commercial polymer, can be prepared by different processes, with polymerization in the presence of free-radical initiators at elevated pressures being the first method and continuing to be a valued process with high commercial relevance for the preparation of polyethylene. A common set-up for preparing polyethylene comprises a polymerization reactor, which can be an autoclave or a tubular reactor or a combination of such reactors, and additional equipment. For pressurizing the reaction components, usually a set of two compressors, a primary compressor and a secondary, or hyper, compressor, is used. At the end of the polymerization sequence, a set-up for high-pressure polymerization normally further includes apparatuses like extruders and granulators for pelletizing the resulting polymer. Furthermore, such a set-up generally also comprises means for feeding monomers and comonomers, free-radical initiators, modifiers or other substances at one or more positions to the polymerization reaction. WO 2017/003566 describes 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) and interstage; and d) a first cooler applied to the interstage piping at a location within 10 meters downstream of the first stage discharge cross-connect pipe. WO 2017/194491 refers to process for the polymerization or copolymerization of one or more ethylenically unsaturated monomers in a continuously operated polymerization reactor wherein the polymerization is carried out in a production line in which the monomers are brought to the polymerization pressure by one or more compressors in a sequence of compression stages in which the compressed gas mixture is cooled after each compression stage by a compression stage cooler, the compressed monomers are optionally passed through a pre-heater or a pre-cooler and transferred into the polymerization reactor which is optionally cooled by cooling jackets, a reaction mixture obtained by the polymerization is leaving the reactor through a pressure control valve and optionally cooled by an post reactor cooler, the reaction mixture is separated into polymeric and gaseous components in two or more stages, where the gaseous components separated off in a first stage at an absolute pressure of from 15 MPa to 50 MPa are recycled to the one or more compressors via a high-pressure gas recycle line, and the gaseous components separated off in a second stage at an absolute pressure in the range of from 0.1 to 0.5 MPa are recycled to the first stage of the sequence of compression stages via a low-pressure gas recycle line, and the polymeric components obtained by the polymerization are transformed into pellets. Within the described process, the surroundings of the production line are monitored with respect to an occurrence of a leakage of monomers or of reaction mixture by an IR point detector arrangement of at least three groups of IR point detectors which are capable of detecting hydrocarbons and the groups of IR point detectors are operating according to a voting logic, and an emergency pressure release program is automatically started when a group of IR point detectors of the IR point detector arrangement detects the presence of hydrocarbons. US 7,582,709 provides a process for the manufacture of ethylene polymers and copolymers comprising the steps of: compressing ethylene in a primary compressor at a throughput of at least 55 tonnes/hour and then mixing that ethylene with recycled ethylene and further compressing the ethylene to a pressure of at least 2300 bar at a throughput of at least 120 tonnes/hour in a secondary compressor, heating at least a portion of the compressed ethylene to a temperature of at least 95° C and introducing that heated ethylene into the front end of a tubular reactor having a maximum internal diameter of at least 65 mm and a length of at least 1500 m, introducing initiator into the tubular reactor in at least three separate locations, thereby defining at least three reaction zones, allowing the et