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EP-4739418-A2 - ONE-PASS DEOXYGENATION METHOD FOR POLYACRYLAMIDE PRODUCTION

EP4739418A2EP 4739418 A2EP4739418 A2EP 4739418A2EP-4739418-A2

Abstract

The present invention relates to a method and apparatus for degassing a monomer composition. In particular, the disclosure provides a method and apparatus for deoxygenation of monomer solutions during transfer from monomer holding tank to reactor. Degassing occurs in one pass by combining a jet of nitrogen with a monomer solution in a Venturi Injector. The inventive degassing methods and apparatus provide enhanced degassing performance.

Inventors

  • CARLETTI, Claudio
  • Bond, Marshall

Assignees

  • KEMIRA OYJ

Dates

Publication Date
20260513
Application Date
20240712

Claims (15)

  1. 1. A method of degassing a monomer composition, the method comprising: (a) providing or producing a liquid monomer composition in a feed tank, wherein said monomer solution comprises an initial dissolved oxygen (DO) content; (b) cooling said monomer solution to a temperature of less than 10 °C, thereby forming a cooled monomer composition; (c) injecting a jet of N 2 gas into a gas inlet of a Venturi Injector at an N 2 flow rate; (d) pumping said cooled monomer composition into a motive fluid inlet of said Venturi Injector at a motive flow rate and allowing said jet of N 2 gas to contact said cooled monomer composition, thereby forming a gas-liquid mixture; (e) pumping said gas-liquid mixture through a length of tubing having an inner diameter (ID); and (f) pumping said gas-liquid mixture through a degasser and allowing gas-liquid separation to occur, thereby forming a degassed monomer composition having a final DO content; wherein steps (a)-(f) are performed in the recited order.
  2. 2. The method of claim 1, the method further comprising: (i) determining the initial DO content of the liquid monomer composition and/or the cooled monomer composition; and (ii) after step (f), determining the final DO content of the degassed monomer composition.
  3. 3. The method of claim 1 or 2, wherein: (i) the initial DO content ranges from 2-20 ppm, 4-18 ppm, 8-16 ppm, or 10-14 ppm; and/or (ii) the final DO content comprises a desired DO content ranging from <500 ppb, 10-500 ppb, 50-450 ppb, 100-400 ppb, or 200-300 ppb.
  4. 4. The method of any one of the foregoing claims, the method further comprising: (i) pumping the gas-liquid mixture through a static mixer upstream of said length of tubing; (ii) pumping the degassed monomer composition to a discharge tank or holding tank; (iii) pumping said degassed monomer composition to a polymerization reactor, wherein a polymerization reaction is initiated; (iv) optionally after step (f) of claim 1, if the final DO content is greater than the desired DO content and/or if further degassing is required, recirculating of said degassed monomer composition into said feed tank and subjecting said degassed monomer composition to a second degassing pass comprising repeating steps (b)-(g) of claim 1; (v) optionally subjecting said degassed monomer composition to a third, fourth, and/or fifth degassing pass, wherein said third, fourth, and/or fifth degassing passes comprise subsequent recirculating of said degassed monomer composition into said feed tank and repeating of steps (b)-(g) of claim 1; or (vi) any combination of (i)-(v).
  5. 5. The method of any one of the foregoing claims, wherein: (i) the feed tank comprises a means of cooling and a means of stirring said liquid monomer composition; (ii) the temperature is sufficiently low to prevent polymerization of said liquid monomer composition and ranges from -5 to 10 °C; 0-10 °C, or 3-5 °C; (ill) the motive flow rate is controlled by a progressive cavity pump arranged in line between said feed tank and said Venturi Injector; (iv) the N2 flow rate is controlled by a gas flow meter and one or more pressure regulators, regulator valves, and/or needle valves arranged in line between a pressurized N2 source and said Venturi Injector; (v) the gas-liquid mixture, when flowing (i) downstream of said Venturi Injector, (ii) between said Venturi Injector and said degasser, or (iii) within said length of tubing, comprises a Reynolds Number (Re) ranging from 2300-8000, 3000-8000, 4000-8000, or 4000-6000, and/or comprises a turbulent flow; (vi) the gas-liquid mixture comprises said cooled monomer composition and a finely divided N2 comprising dissolved N2, atomized N2, microscopic N2 bubbles, and/or macroscopic N2 bubbles, wherein said finely divided N2 is sufficiently small to allow gas-liquid mass transfer of DO, dissolved gasses, and/or volatile molecules from said cooled monomer composition to said finely divided N2, thereby allowing for removal of said DO, dissolved gasses, and/or volatile molecule from said cooled monomer composition; (vii)the length of tubing provides a residence time for said gas-liquid mixture between said Venturi Injector and said degasser and optionally comprises coil tubing; (viii) the degasser comprises a hydro separator and a gas vent; or (ix) any combination of (i)-(viii).
  6. 6. The method of any one of the foregoing claims, wherein one or more of the following is adjusted to achieve the desired final DO content: (i) the Reynolds Number characterizing said gas-liquid mixture; (ii) the N2 flow rate; (iii) the motive flow rate; (iv) the inner diameter (ID) of the length of tubing; (v) a length (L) of the length of tubing; or (vi) any combination of (i)-(v).
  7. 7. The method of any one of the foregoing claims, wherein the liquid monomer composition comprises: (a) an aqueous monomer solution comprising water and at least one monomer comprising one or more nonionic monomers, one or more anionic monomers, one or more cationic monomers, or any combination thereof; wherein (i) said one or more nonionic monomers are selected from the group of primary amide- containing monomers comprising acrylamide, methacrylamide, ethyl acrylamide, crotonamide, N-methyl acrylamide, N-butyl acrylamide, N-ethyl methacrylamide, and any combination thereof; (ii) said one or more cationic monomers are selected from are selected from acryloyloxyethyltrimethyl ammonium chloride ("AETAC"), methacryloyloxyethyltrimethylammonium chloride ("MAETAC"), methacrylamidopropyltrimethylammonium chloride ("MAPTAC"), acrylamidopropyltrimethylammonium chloride ("APTAC"), methacryloyloxyethyldimethylammonium sulfate, diallyldimethylammonium chloride ("DADMAC"); dialkylaminoalkyl acrylates and dialkylaminoalkyl methacrylates and their quaternary or acid salts, including but not limited to, dimethylaminoethyl acrylate ("DMAEA"), dimethylaminoethyl methacrylate ("DMAEA"), dimethylaminoethyl acrylate methyl chloride quaternary salt, dimethylaminoethyl acrylate methyl sulfate quaternary salt, dimethylaminoethyl acrylate benzyl chloride quaternary salt, dimethylaminoethyl acrylate sulfuric acid salt, dimethylaminoethyl acrylate hydrochloric acid salt, diethylaminoethyl acrylate methyl chloride quaternary salt, dimethylaminoethyl methacrylate methyl chloride quaternary salt, dimethylaminoethyl methacrylate methyl sulfate quaternary salt, dimethylaminoethyl methacrylate benzyl chloride quaternary salt, dimethylaminoethyl methacrylate sulfuric acid salt, dimethylaminoethyl methacrylate hydrochloric acid salt, dimethylaminoethyl methacryloyl hydrochloric acid salt; dialkylaminoalkylacrylamides and methacrylamides and their quaternary or acid salts, including but not limited to, acryloylamidopropyltrimethylammonium chloride, dimethylaminopropyl acrylamide, dimethylaminopropyl acrylamide methyl sulfate quaternary salt, dimethylaminopropyl acrylamide sulfuric acid salt, dimethylaminopropyl acrylamide hydrochloric acid salt, methacrylamidopropyltrimethylammonium chloride, dimethylaminopropyl methacrylamide, dimethylaminopropyl methacrylamide methyl sulfate quaternary salt, dimethylaminopropyl methacrylamide sulfuric acid salt, dimethylaminopropyl methacrylamide hydrochloric acid salt, diethylaminoethylacrylate, diethylaminoethylmethacrylate; and diallyldialkylammonium halides, including but not limited to, diallyldiethylammonium chloride and diallyldimethylammonium chloride ("DADMAC"), and any combination thereof; and (ill) said one or more anionic monomers contain functional groups selected from carboxylic acids, sulfonic acids, a phosphonic acids, their corresponding water soluble salts, their corresponding water dispersible salts, and any combination thereof, including but not limited to, acrylic acid, methacrylic acid, maleic acid, itaconic acid, vinyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), acrylamido tertiary butyl sulfonic acid (ATBS), acrylamido methanesulfonic acid, acrylamido ethanesulfonic acid, 2-hydroxy-3-acrylamide propane sulfonic acid, styrene sulfonic acid, and vinyl phosphonic acid, their corresponding alkali metal, alkaline earth metal, and ammonium salts, and any combination thereof; (b) comprises 1-70%, 5-50%, 25-45%, or 30-40% by weight of said at least one monomer; or (c) any combination of (a )(i)-(iii) and/or (b).
  8. 8. The method of any one of the foregoing claims, wherein (a) the liquid monomer composition comprises acrylamide, acrylic acid, acrylamido tertiary butyl sulfonic acid (ATBS), or any combination thereof; or (b) the degassed monomer composition is used to produce a dry polyacrylamide (DPAM) or an emulsion polyacrylamide (EPAM).
  9. 9. The method of any one of the foregoing claims, wherein: (a) the method results in said degassed monomer composition having the desired final DO content after a first degassing pass, wherein the first degassing pass comprises a single application of steps (a)-(f) of claim 1; and/or (b) the method results in (i) an increased monomer degassing capacity, (ii) a reduced monomer degassing time, (ill) a decreased N 2 consumption, or (iv) any combination of (i)-(iii), compared to a conventional method of degassing a monomer composition comprising sparging N 2 gas through a pipe or bubbling column into a bulk monomer composition in a reactor or holding tank.
  10. 10. A degassed monomer composition obtainable by a method according to any one of claims 1-9, wherein the degassed monomer composition comprises a desired final DO content ranging from <500 ppb, 10-500 ppb, 50-450 ppb, 100-400 ppb, or 200-300 ppb.
  11. 11. An apparatus for degassing a monomer composition, the apparatus comprising: (a) a monomer feed tank comprising a means of cooling and a means of stirring a liquid monomer composition, optionally comprising a liquid monomer composition comprising an initial dissolved oxygen (DO) content according to any one of claims 1, 3, 7 or 8; (b) a means of controlling a motive flow rate of said liquid monomer composition, a pipe, and a Venturi Injector comprising a motive fluid inlet, a gas inlet, and an outlet, wherein said means of controlling motive flow rate and said pipe are arranged in line between said monomer feed tank and said motive fluid inlet on said Venturi Injector; (c) a pressurized N 2 source and a means of controlling a N 2 flow rate arranged in line with said gas inlet on said Venturi Injector; and (d) a length of tubing having an inner diameter (ID) and a degasser, wherein said length of tubing is arranged in line between said outlet on said Venturi Injector and said degasser.
  12. 12. The apparatus of claim 11, further comprising: (a) a dissolved oxygen (DO) meter arranged in contact with said liquid monomer composition and upstream of said Venturi Injector; and/or (b) a second dissolved oxygen (DO) meter arranged in contact with a degassed liquid monomer composition and downstream of said degasser.
  13. 13. The apparatus of claim 11 or 12, further comprising: (a) a means of gas-liquid mixing, optionally a static mixer, arranged downstream of said degasser; (b) a discharge tank, holding tank, or polymerization reactor arranged downstream of said degasser; (c) a means of flowing N 2 into said discharge tank, holding tank, or polymerization reactor; (d) optionally, a means of recirculating said degassed liquid monomer composition into said monomer feed tank or directly into motive fluid inlet on said Venturi Injector; or (e) any combination of (a) to (d) or any combination of (a) and (c).
  14. 14. The apparatus of any one of claims 11-13, wherein: (a) said means of cooling comprises a cooling coil and said means of stirring comprises a stirrer; (b) said means of controlling a motive flow rate comprises a progressive cavity pump and a monomer flowmeter; (c) said means of controlling a N 2 flow rate comprises a gas flowmeter and one or more N 2 pressure regulators, one or more N 2 regulator valves and/or one or more N 2 needle valves arranged in line between said pressurized N 2 source and said gas inlet on said Venturi Injector; (d) said length of tubing comprises straight tubing or pipe, coil tubing or pipe, or a combination thereof; (e) said degasser comprises a hydro separator and a gas vent; or (f) any combination of (a)-(e).
  15. 15. The apparatus of any one of claims 11-14, further comprising: (a) one or more pressure sensors, one or more flowmeters, one or more rotameters; (b) a feed tank discharge valve arranged in line between said monomer feed tank and said progressive cavity pump; (c) a hydro separator discharge valve arranged downstream of said degasser; or (d) any combination of (a) to (c).

Description

ONE-PASS DEOXYGENATION METHOD FOR POLYACRYLAMIDE PRODUCTION RELATED APPLICATIONS [0001] The present invention relates to and claims benefit of priority to U.S. Provisional Application Number 63/513,517, filed on July 13, 2023, and Finnish Application Number FI 20236045, filed on September 21, 2023, the contents of both are which are incorporated by reference in their entirety herein. FIELD OF THE INVENTION [0002] The present invention relates to a method and apparatus for degassing a monomer composition. In particular, the disclosure provides a method and apparatus for deoxygenation of monomer solutions during transfer from monomer holding tank to reactor. Degassing occurs in one pass by combining a jet of nitrogen with a monomer solution in a Venturi Injector. BACKGROUND OF THE INVENTION [0003] Monomer degassing is a particularly important unit operation step in polymer manufacturing, specifically for acrylamide polymers, namely emulsion polyacrylamides (EPAMs) and dry polyacrylamides (DP AMs) among other polymer products. The presence of dissolved oxygen (DO) tends to inhibit polymerization in monomer solutions, thereby allowing for monomer solutions to be prepared and pumped into feed tanks without unwanted polymerization before pumping into a polymerization reactor. Typically, the monomer solution is transferred to a polymerization reactor and then degassed by various methods prior to initiation of polymerization. [0004] In a first commonly used degassing option, the monomer mixture is degassed in a tipping reactor after it has been cooled, examples of this method are implemented in existing polymer production plants. In tipping reactor applications, after pumping a monomer solution into the reactor, N2 is sparged into the bulk monomer solution through a pipe inlet for 40 to 60 min or more. This allow for target DO values of < 500 ppb (more preferably < 200 ppb) to be achieved. These target DO values must be achieved prior to initiation of polymerization. [0005] A second degassing option consists of sparging and degassing a monomer solution using bubbling columns. N2 is sparged into the bulk monomer solution through the bubbling columns. The introduction of gas takes place at the bottom of the column and causes a turbulent stream to enable gas exchange. This second method is used in several industrial applications, but is not suitable for tipping reactors due to the large flowrates required in tipping reactors with respect to belt reactor technologies. [0006] Both tipping reactor and bubbling column degassing options require enormous volumes of nitrogen gas and undesirably long degassing times. 1 SUBSTITUTE SHEET (RULE 26) [0007] The present invention addresses these limitations and needs by providing novel and efficient method and apparatus for degassing monomer solutions using a Venturi Injector. This invention proposes a novel system and procedure for deoxygenation of a monomer solution during transfer from holding tank to reactor. Monomer can be transferred after cooling and degassed cold during transfer from monomer holding tank to reactor. [0008] It is an object of the invention to provide a method and apparatus for degassing by means of a Venturi Injector in one pass during transfer of monomer solution from feed tank to reactor. The inventive method allows for degassing to occur in one pass by injecting pressurized nitrogen into a Venturi Injector. SUMMARY OF THE INVENTION [0009] The present invention relates to a method and apparatus for degassing a monomer composition. In particular, the disclosure provides a method and apparatus for deoxygenation of monomer solutions during transfer from monomer holding tank to reactor. Degassing occurs in one pass by combining a jet of nitrogen with a monomer solution in a Venturi Injector. The inventive method and apparatus provide a more efficient degassing, allowing for an increased monomer degassing capacity, a reduced monomer degassing time, and decreased N2 consumption compared to traditional degassing methods. [0010] In one aspect, the present invention provides a method of degassing a monomer composition, the method comprising: [0011] (a) providing or producing a liquid monomer composition in a feed tank, wherein said monomer solution comprises an initial dissolved oxygen (DO) content; [0012] (b) cooling said monomer solution to a temperature of less than 10 °C, thereby forming a cooled monomer composition; [0013] (c) injecting a jet of N2 gas into a gas inlet of a Venturi Injector at an N2 flow rate; [0014] (d) pumping said cooled monomer composition into a motive fluid inlet of said Venturi Injector at a motive flow rate and allowing said jet of N2 gas to contact said cooled monomer composition, thereby forming a gas-liquid mixture; [0015] (e) pumping said gas-liquid mixture through a length of tubing having an inner diameter (ID); and [0016] (f) pumping said gas-liquid mixture through a degasser and allowing gas-liquid separation to occur, thereb