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KR-102962429-B1 - Solution polymerization process

KR102962429B1KR 102962429 B1KR102962429 B1KR 102962429B1KR-102962429-B1

Abstract

The present invention discloses a system for solution polymerization comprising: a reactor system that receives an anti-solvent, a monomer, and a solvent and operates to react the monomer to produce a polymer, wherein the anti-solvent is not a solvent for the polymer and the reactor system is operated to reduce a lower critical solution temperature; a plurality of devolatilization vessels located downstream of the reactor system, wherein each devolatilization vessel is operated at a lower pressure than the previous devolatilization vessel and the plurality of devolatilization vessels receive a polymer solution from the reactor system; and a liquid-liquid separator that receives a polymer solution from the reactor system and operates to facilitate separation between the polymer and the volatile substance by reducing the pressure and temperature of the polymer solution in the liquid-liquid separator.

Inventors

  • 왕, 알렉 와이.
  • 루발카바, 조지
  • 터너, 마이클 디.
  • 조그, 주니어, 마이클 제이.
  • 제인, 프라딥

Assignees

  • 다우 글로벌 테크놀로지스 엘엘씨

Dates

Publication Date
20260511
Application Date
20191213
Priority Date
20181214

Claims (15)

  1. As a solution polymerization system, A reactor system that accommodates an anti-solvent, a monomer, and a solvent and operates to react the monomer to produce a polymer, wherein the anti-solvent is not a solvent for the polymer and is operated to reduce a lower critical solution temperature, and wherein the reactor system comprises a first reactor and a second reactor, wherein the second reactor is operated at a higher temperature and a lower pressure than the first reactor; A liquid-liquid separator that receives a polymer solution from a reactor system and operates to facilitate separation between the polymer and a volatile substance by reducing the pressure and temperature of the polymer solution in the liquid-liquid separator, wherein the polymer exists in a polymer-rich phase and the volatile substance exists in a solvent-rich phase comprising a solvent and unreacted monomers; and A plurality of devolatilization vessels located downstream of a liquid-liquid separator, wherein each devolatilization vessel is operated at a lower pressure than a previous devolatilization vessel, and the plurality of devolatilization vessels comprises a plurality of devolatilization vessels that receive a polymer-rich phase from a liquid-liquid separator. Here, the antisolvent is ethane, the monomer is an α-olefin, and the solvent is methylcyclohexane, and A solution polymerization system in which the above liquid-liquid separator is located between the reactor system and the first devolatilization vessel and operates at a pressure greater than 70 kgf/ cm² and less than 92 kgf/ cm² and a temperature separating the polymer and volatile substances.
  2. delete
  3. A solution polymerization system according to claim 1, wherein the reactor system comprises a first reactor operated at a temperature of 120°C to 230°C and a pressure of 90 kgf/ cm² or more to 200 kgf/ cm² or less.
  4. A solution polymerization system according to claim 3, wherein the solid content in the polymer solution is present in an amount of 8 to 16 weight percent based on the total weight of the polymer solution at the outlet of the first reactor.
  5. delete
  6. A solution polymerization system according to claim 1, wherein the second reactor is operated at a pressure of 80 kgf/ cm² or more to 180 kgf/ cm² or less and a temperature of 200 to 240°C.
  7. ◈Claim 7 was waived upon payment of the establishment registration fee.◈ A solution polymerization system according to claim 6, wherein the solid content in the polymer solution is present in an amount of 12 to 20 weight percent based on the total weight of the polymer solution at the outlet of the second reactor.
  8. ◈Claim 8 was waived upon payment of the establishment registration fee.◈ A solution polymerization system according to claim 1, wherein the pressure within the liquid-liquid separator is greater than the bubble point of the polymer solution.
  9. ◈Claim 9 was waived upon payment of the establishment registration fee.◈ A solution polymerization system according to claim 1, wherein the pressure of the polymer solution in the liquid-liquid separator is reduced from 180 kgf/ cm² to more than 70 kgf/ cm² and less than 92 kgf/ cm² , and the solid content of the polymer solution exiting the liquid-liquid separator is 20 to 24 weight%.
  10. ◈Claim 10 was waived upon payment of the establishment registration fee.◈ A solution polymerization system according to claim 1, wherein the plurality of devolatilization vessels comprises a first devolatilization vessel operated to increase the solid content in the polymer stream to at least 60 weight percent of the polymer based on the total weight of the polymer solution leaving the first devolatilization vessel.
  11. ◈Claim 11 was waived upon payment of the establishment registration fee.◈ A solution polymerization system according to claim 10, wherein the plurality of devolatilization vessels further comprises a second devolatilization vessel operated to increase the solid content in the polymer stream to at least 90 weight percent of the polymer based on the total amount of polymer solution leaving the second devolatilization vessel.
  12. ◈Claim 12 was waived upon payment of the establishment registration fee.◈ A solution polymerization system according to claim 1, wherein the volatile substances generated in the plurality of devolatilization vessels are recirculated back to the reactor system.
  13. ◈Claim 13 was waived upon payment of the establishment registration fee.◈ As a method, A step of charging a feed stream comprising an antisolvent, a monomer, and a solvent into a reactor system, wherein the antisolvent is not a solvent for the polymer and is operated to reduce the lower critical solution temperature of the polymer solution, the reactor system comprises a first reactor and a second reactor, the second reactor is operated at a higher temperature and lower pressure than the first reactor, the antisolvent is ethane, the monomer is an α-olefin, and the solvent is methylcyclohexane; A step of reacting monomers to produce a polymer, wherein the polymer is contained in a polymer solution; A step of transporting the polymer solution phase to a liquid-liquid separator; A step of reducing the pressure of the polymer solution in a liquid-liquid separator and separating the polymer-rich phase from the solvent-rich phase in the liquid-liquid separator; A step of transporting a polymer-rich phase to a plurality of devolatilization vessels located downstream of a liquid-liquid separator, wherein each devolatilization vessel is operated at a lower pressure than the previous devolatilization vessel; and The method includes the step of separating the polymer from volatile substances present in a polymer-rich phase. Herein, the liquid-liquid separator is located between the reactor system and the first devolatilization vessel and is operated at a pressure greater than 70 kgf/ cm² and less than 92 kgf/ cm² and at a temperature separating the polymer and the volatile substance, a method.
  14. ◈Claim 14 was waived upon payment of the establishment registration fee.◈ A method according to claim 13, further comprising the step of pelletizing the polymer.
  15. A method according to claim 13, further comprising the step of recirculating a volatile substance into the reactor system.

Description

Solution polymerization process Cross-reference of related applications This application claims priority to U.S. Application No. 62/779,589, filed on December 14, 2018, the entire contents of which are incorporated herein by reference. The present disclosure relates to a solution polymerization process. In particular, the present disclosure relates to a solution polymerization process integrated with an upstream ethylene plant using a mixture of a solvent and a non-solvent. Polymer solutions can exhibit the Lower Critical Solution Temperature (LCST) phenomenon, causing a homogeneous polymer solution to separate into a polymer-rich liquid phase and a solvent-rich phase above a certain temperature. This temperature is correlated with the type of solvent, the polymer stream composition, and the pressure. Any of these variables can be manipulated to induce liquid-liquid separation. This separation involves a very small associated heat duty, particularly compared to the vaporization of an equivalent amount of solvent. In commercial solution polymerization, it is necessary to increase the efficiency associated with the solvent removal process while reducing costs. Friedersdorf’s U.S. Patent No. 6,881,800 relates to a process and plant for continuous solution polymerization. The plant comprises a pressure source; a polymerization reactor downstream of the pressure source; a depressurization device located downstream of the polymerization reactor; and a separator located downstream of the depressurization device. The pressure source is disclosed to be sufficient to provide pressure to the reaction mixture during polymerization when there is no additional pressure source between the reactor and the separator to produce a single-phase liquid reaction mixture in the reactor and a two-phase liquid-liquid reaction mixture in the separator. The process discloses the use of a heater to heat the reactor discharge stream before inducing liquid-liquid phase separation. Since the solution leaving the reactor contains more solvent per pound of polymer than the solution leaving the separator, heating before the separator significantly increases the heat load per pound of polymer. International Publication WO 2008/076589 by Friedersdorf et al. discloses a process for polymerizing olefins in a homogeneous polymerization system of concentrated fluids. This process comprises: (a) contacting an olefin monomer having three or more carbon atoms present in at least 30 wt% in one or more reactors with the following: 1) one or more catalyst compounds, 2) one or more activators, 3) 0 to 50 mol% of a comonomer, and 4) 0 to 40 wt% of a diluent or solvent; (b) generating a reactor effluent comprising a polymer-monomer mixture; (c) optionally, heating the polymer-monomer mixture of (b) after the polymer-monomer mixture of (b) has exited the reactor and before or after the pressure is reduced in (e); and (d) collecting the polymer-monomer mixture of (b) in a separation vessel. (e) a step of reducing the pressure of the reactor effluent containing the polymer-monomer mixture of (b) to below the cloud point pressure to produce a two-phase mixture containing a polymer-rich phase and a monomer-rich phase, either before or after collecting the polymer-monomer mixture from the separation vessel. The pressure inside the reactor is 7 to 100 MPa higher than the pressure inside the separation vessel, and the temperature inside the separation vessel is greater than the higher of the crystallization temperatures of the polymer, or greater than 80°C if the polymer does not possess a crystallization temperature. The monomer-rich phase is separated from the polymer-rich phase and recirculated to one or more reactors. The patent discloses that the pressure of the reactor used to operate the process with less than 40 wt% solvent is high (up to 200 MPa) to ensure a supercritical polymerization medium. Such high pressure makes reactor operation difficult and requires the use of a thick-walled reactor, thereby reducing capital and energy efficiency. U.S. Patent No. 6,255,410 by Shigekauzu et al. discloses a process for producing polyolefins at a pressure substantially lower than the normal high-pressure conditions of a two-phase system. This process comprises: (a) continuously feeding an olefin monomer and a catalytic system of a metalocene and a co-catalyst; (b) continuously polymerizing the monomer feed to provide a monomer-polymer mixture; and (c) continuously settling the two-phase mixture into a continuous molten polymer phase and a continuous monomer vapor, the latter of which may optionally be recirculated at least partially to (a). In (b), the mixture is at a pressure below the cloud point pressure to provide a polymer-rich phase and a monomer-rich phase at a temperature above the melting point of the polymer, and polymerization is carried out at a temperature and pressure exceeding that obtained at twice the pressure above the cloud point at said tempera