One-pass deoxygenation method for polyacrylamide production

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.

Description

ONE-PASS DEOXYGENATION METHOD FOR POLYACRYLAMIDE PRODUCTIONRELATED 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.1SUBSTITUTE 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, thereby forming a degassed monomer composition having a final DO content;

[0017] wherein steps (a)-(f) are performed successively.

[0018] In some exemplary embodiments the method further comprises

[0019] (a) determining said initial DO content of said liquid monomer composition and / or said cooled monomer composition; and

[0020] (b) after step (f), determining said final DO content of said degassed monomer composition.

[0021] In some exemplary embodiments of the method:2SUBSTITUTE SHEET (RULE 26)

[0022] (a) said initial DO content ranges from 2-20 ppm, 4-18 ppm, 8-16 ppm, or 10-14 ppm; and / or

[0023] (b) said 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.

[0024] In some exemplary embodiments the method further comprises:

[0025] (a) pumping said gas-liquid mixture through a static mixer upstream of said length of tubing;

[0026] (b) pumping said degassed monomer composition to a discharge tank or holding tank;

[0027] (c) pumping said degassed monomer composition to a polymerization reactor, wherein a polymerization reaction is initiated;

[0028] (d) optionally after step (f), if said final DO content is greater than said desired DO content and / or if further degassing is required, recirculating said degassed monomer composition into said feed tank and subjecting said degassed monomer composition to a second degassing pass comprising repeating steps (b)-(g);

[0029] (e) 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; or.

[0030] (f) any combination of (a)-(e).

[0031] In some exemplary embodiments of the method:

[0032] (a) said feed tank comprises a means of cooling and a means of stirring said liquid monomer composition;

[0033] (b) said 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;

[0034] (c) said motive flow rate is controlled by a progressive cavity pump arranged in line between said feed tank and said Venturi Injector;

[0035] (d) said 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;

[0036] (e) said 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;

[0037] (g) said 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;

[0038] (h) said length of tubing provides a residence time for said gas-liquid mixture between said Venturi Injector and said degasser and optionally comprises coil tubing;3SUBSTITUTE SHEET (RULE 26)

[0039] (i) said degasser comprises a hydro separator and a gas vent; or

[0040] (j) any combination of (a)-(h).

[0041] In some exemplary embodiments of the method one or more of the following is adjusted to achieve said desired final DO content:

[0042] (a) said Reynolds Number characterizing said gas-liquid mixture;

[0043] (b) said N2 flow rate;

[0044] (c) said motive flow rate;

[0045] (d) said inner diameter (ID) of said length of tubing;

[0046] (e) a length (L) of said length of tubing; or

[0047] (f) any combination of (a)-(e).

[0048] In some exemplary embodiments of the method said liquid monomer composition comprises:

[0049] (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

[0050] (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;

[0051] (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,4SUBSTITUTE SHEET (RULE 26)including but not limited to, diallyldiethylammonium chloride and diallyldimethylammonium chloride (“DADMAC”), and any combination thereof; and

[0052] (iii) 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-acryIamide propane sulfonic acid, styrene sulfonic acid, and vinyl phosphonic acid, their corresponding alkali metal, alkaline earth metal, and ammonium salts, and any combination thereof;

[0053] (b) comprises 1-70%, 5-50%, 25-45%, or 30-40% by weight of said at least one monomer; or

[0054] (c) any combination of (a)-(c).

[0055] In some exemplary embodiments of the method:

[0056] (a) said liquid monomer composition comprises acrylamide, acrylic acid, acrylamido tertiary butyl sulfonic acid (ATBS), or any combination thereof; or

[0057] (b) said degassed monomer composition is used to produce a dry polyacrylamide (DP AM) or an emulsion polyacrylamide (EPAM).

[0058] In some exemplary embodiments of the method:

[0059] (a) the method results in said degassed monomer composition having said desired final DO content after a first degassing pass, wherein said first degassing pass comprises a single application of steps (a)-(f) of claim 1 ; and / or

[0060] (b) the method results in (i) an increased monomer degassing capacity, (ii) a reduced monomer degassing time, (iii) a decreased N2 consumption, or (iv) any combination of (i)-(iii), compared to a conventional method of degassing a monomer composition comprising sparging N2 gas through a pipe or bubbling column into a bulk monomer composition in a reactor or holding tank.

[0061] In another aspect, the present invention provides a degassed monomer composition obtainable by a method according to any of claims 1-9, wherein said 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.

[0062] In another aspect, the present invention provides an apparatus for degassing a monomer composition, the apparatus comprising:

[0063] (a) a monomer feed tank comprising a means of cooling and a means of stirring a liquid monomer composition;

[0064] (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;

[0065] (c) a pressurized N2 source and a means of controlling a N2 flow rate arranged in line with said gas inlet on said Venturi Injector; and5SUBSTITUTE SHEET (RULE 26)

[0066] (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.

[0067] In some exemplary embodiments the apparatus further comprises:

[0068] (a) a dissolved oxygen (DO) meter arranged in contact with said liquid monomer composition and upstream of said Venturi Injector; and / or

[0069] (b) a second dissolved oxygen (DO) meter arranged in contact with a degassed liquid monomer composition and downstream of said degasser.

[0070] In some exemplary embodiments the apparatus further comprises

[0071] (a) a means of gas-liquid mixing, optionally a static mixer, arranged downstream of said degasser;

[0072] (b) a discharge tank, holding tank, or polymerization reactor arranged downstream of said degasser;

[0073] (c) a means of flowing N2 into said discharge tank, holding tank, or polymerization reactor;

[0074] (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

[0075] (e) a combination of (a) and (c).

[0076] In some exemplary embodiments of the apparatus:

[0077] (a) said means of cooling comprises a cooling coil and said means of stirring comprises a stirrer;

[0078] (b) said means of controlling a motive flow rate comprises a progressive cavity pump and a monomer flowmeter;

[0079] (c) said means of controlling a N2 flow rate comprises a gas flowmeter and one or more N2 pressure regulators, one or more N2 regulator valves and / or one or more N2 needle valves arranged in line between said pressurized N2 source and said gas inlet on said Venturi Injector;

[0080] (d) said length of tubing comprises straight tubing or pipe, coil tubing or pipe, or a combination thereof;

[0081] (e) said degasser comprises a hydro separator and a gas vent; or

[0082] (f) any combination of (a)-(e).

[0083] In some exemplary embodiments the apparatus further comprises:

[0084] (a) one or more pressure sensors, one or more flowmeters, one or more rotameters;

[0085] (b) a feed tank discharge valve arranged in line between said monomer feed tank and said progressive cavity pump;

[0086] (c) a hydro separator discharge valve arranged downstream of said degasser.BRIEF DESCRIPTION OF THE DRAWINGS

[0087] The invention will be described in more detail with reference to appended drawings, described in detail below.6SUBSTITUTE SHEET (RULE 26)

[0088] FIG 1 provides an exemplary Pipe and Instrumentation Diagram (PID) with numbering for a degassing test unit according to Example 1.

[0089] FIG 2 provides an exemplary rendering of a degassing test unit according to Example 1.

[0090] FIG 3 provides an exemplary rendering of a pilot plant layout of a degassing test unit according to Example 1.

[0091] FIG 4 provides an exemplary image of a pilot plant layout of a degassing test unit as built in Aberdeen, USA according to Example 1.

[0092] FIG 5 provides a second exemplary image of a pilot plant layout of a degassing test unit as built in Aberdeen, USA according to Example 1.

[0093] FIG 6 provides a third exemplary image of a pilot plant layout of a degassing test unit as built in Aberdeen, USA according to Example 1.

[0094] FIG 7 provides a fourth exemplary image of a pilot plant layout of a degassing test unit as built in Aberdeen, USA according to Example 1.

[0095] FIG 8 provides an exemplary graph of modeling results for dissolved oxygen (DO) vs. pipe length according to Example 2.

[0096] FIG 9 provides an exemplary graph of the statistical effect summary of main parameters on DO content according to Example 4.

[0097] FIG 10 provides an exemplary dissolved oxygen (DO) prediction plot showing actual DO vs predicted DO according to Example 4.

[0098] FIG 11 provides exemplary graphs of statistical profiles showing the effect of main parameters on DO content and degassing time according to Example 4.DETAILED DESCRIPTION OF THE INVENTION

[0099] Before describing the invention, the following definitions are provided. Unless stated otherwise all terms are to be construed as they would be by a person skilled in the art.DEFINITIONS

[0100] All technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs unless clearly indicated otherwise.

[0101] As used herein the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. The singular forms “a,” “an,” and “the” may mean “one” but also include plural referents such as “one or more” and “at least one” unless the context clearly dictates otherwise.

[0102] As used herein, the term “or” in the claims is used to mean “and / or” unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and / or.”

[0103] As used herein, the term “about” means plus or minus 10% of the numerical value of the number with which it is being used.7SUBSTITUTE SHEET (RULE 26)

[0104] As used herein the term “or combinations thereof’ as used herein refers to all permutations and combinations of the listed items preceding the term unless stated otherwise.

[0105] Process and Apparatus

[0106] The term “in-line” refers to any components or equipment in an industrial apparatus that are connected to other components or equipment by piping, tubing, or any conduit through which an industrial process stream (e.g. , monomer solution) may flow, for example by means of pumping.

[0107] As used herein, the terms “upstream” and “downstream”, refer to relative orientation of components, equipment, or materials within an industrial process or apparatus through which fluid or liquid material may flow, for example by means of pumping. A pumped fluid encounters an upstream location prior to encountering a downstream location.

[0108] As used herein, the term “one pass” or “first pass” , refers to a subjecting a monomer solution to a single application of degassing through an apparatus of the present invention.

[0109] As used herein, the term “residence time” refers to the contact time between nitrogen gas and an industrial process stream (e.g., monomer solution) prior to degassing.

[0110] As used herein, the term “Reynolds number” or “Re” is a dimensionless quantity in fluid mechanics that helps predict flow patterns of fluids and fluid-gas mixtures in different situations by measuring the ratio between inertial and viscous forces. For the present invention, Reynolds Number (Re) refers to the gas-liquid mixture that forms when pressurized N2 gas is forced into a liquid monomer through the gas inlet of a Venturi Injector, thereby mixing with the liquid monomer motive fluid, which is pumped into the motive fluid inlet of the Venturi Injector. When the N2 gas contacts with the liquid monomer, a gas-liquid mixture is formed, which is pumped downstream of the Venturi Injector, optionally through a static mixer, and further optionally through a length of tubing, and into a degasser. At low Reynolds numbers, the gas-liquid mixture flow tends to be dominated by laminar (sheet-like) flow, while at high Reynolds numbers, turbulent flow is dominant. Reynolds number for a flowing gas-liquid mixture may be calculated by any of several methods known in the art. Laminar flow occurs when the calculated Reynolds number is less than 2300. Reynolds numbers exceeding 4000 indicate turbulent flow. When flow occurs between Laminar and Turbulent flow conditions (Re 2300 to Re 4000), the flow condition is known as critical. Critical flow is neither wholly laminar nor wholly turbulent and is a combination of the two flow conditions.

[0111] As used herein, the term “motive flow rate” refers to the flow rate of a liquid into the motive fluid inlet a Venturi Injector.

[0112] As used herein, the term “Venturi injector” refers to an eductor, which has been adapted to accept a pressurized N2 stream. The term “eductor” generally refers to a device used to mix a gas with a liquid. When pressurized water enters the injector inlet, it is constricted toward the injection chamber and changes into a high-velocity jet stream. Typically, the increase in velocity through the vena contracta results in a decrease in absolute pressure, creating a vacuum that draws a liquid or gas (e.g., N2) additive through the suction port and mixes it thoroughly into the motive force fluid stream. In other words, as the fluid passes through the small diameter of the venturi (vena contracta) the pressure decreases, which causes a vacuum based on Bernoulli's law. As the jet stream is diffused toward the injector outlet, its velocity is reduced and resumes its flow in a thoroughly mixed state with slightly lower energy than when it entered the injector.8SUBSTITUTE SHEET (RULE 26)

[0113] For the present invention, a pressurized N2 gas stream is injected or forced through the gas inlet of a Venturi Injector (i.e., an eductor) into the liquid monomer motive fluid stream, thereby providing for a higher N2 flow rate into the liquid stream and more turbulent flowing gas-liquid mixture than would otherwise be achievable under the vacuum formed by the Bernoulli effect. This results in an N2 gas-liquid mixture having a turbulent flow as it is pumped between the Venturi Injector and degasser. In certain exemplary embodiments, the Reynolds Number (Re) for the N2 gasliquid mixture, when flowing (i) downstream of said Venturi Injector, (ii) between said Venturi Injector and said degasser, or (iii) within said length of tubing, is greater than 2300, greater than 4000, greater than 5000, or greater than 6000 for at least part of the distance between the Venturi Injector and degasser. In other embodiments, the Reynolds Number (Re) for the N2 gas-liquid mixture is greater than 4000, greater than 5000, or greater than 6000 for at least part or all of the distance between the Venturi Injector and degasser. A Reynolds Number greater than 4000 for a flowing gas / liquid mixture indicates turbulent flow.

[0114] In some embodiments, other forms of eductors may be directly used or adapted for use as a device for mixing pressurized or forced N2 gas into the liquid polymer motive fluid. In some embodiments, the other forms of eductors include a hootenanny or liquid jet pump, which is a simple type of pump that uses the Venturi effect to pump or move a fluid (air, liquid or gas) in an enclosed line.

[0115] Industrial Process Streams

[0116] As used herein, the term “process stream” or “industrial process stream” generally refers to any aqueous fluids, solutions, slurries, or dispersions produced during any type of industrial process, for example, processes relating to chemical manufacturing, polymer manufacturing, pulp and paper industry, oil or gas extraction or recovery including recovery, extraction, refining, or waste treatment, waste treatment, water treatment, paints and coatings, food and beverage processing, mining industries, textiles, agriculture, or any portion thereof. An exemplary embodiment of a process stream includes an aqueous monomer solution to be degassed and polymerized. The inventive method and apparatus for degassing may be applied to any process stream wherein degassing of an aqueous solution or process stream is required.

[0117] As used herein, the term “aqueous solution” or “solution” refers to a mixture of water and a water-soluble solute or solutes which are completely dissolved with little to no residual undissolved solute (e.g., monomer). The solution may be homogenous.

[0118] As used herein, the terin “emulsion” refers to multiphasic fluid systems in which liquid droplets are dispersed in another immiscible liquid. An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) exhibiting liquid-liquid phase separation. Emulsions comprise two phases, “dispersed / intemal phase” and “continuous / extemal phase”, which are liquids. In an emulsion, one liquid (the dispersed phase) is suspended or dispersed throughout the other liquid (the continuous phase) in separate droplets. Typical main components of an emulsion are the two liquid phases, typically oil and water, and an emulsifier, which stabilizes the interface between the two liquid phases. Emulsifiers can be a variety of molecules, such as polymers, amphiphilic surfactants, and proteins, and they can also be colloidal particles.

[0119] Polymers

[0120] As used herein, the terms “polymer” or “polymeric additives” and similar terms are used in their ordinary sense as understood by one skilled in the art, and thus may be used herein to refer to or9SUBSTITUTE SHEET (RULE 26)describe a large molecule (or group of such molecules) that may comprise recurring units. Polymers may be formed in various ways, including by polymerizing monomers and / or by chemically modifying one or more recurring units of a precursor polymer. Unless otherwise specified, a polymer may comprise a “homopolymer” that may comprise substantially identical recurring units that may be formed by, for example, polymerizing a particular monomer. Unless otherwise specified, a polymer may also comprise a "copolymer” that may comprise two or more different recurring units that may be formed by, for example, copolymerizing, two or more different monomers, and / or by chemically modifying one or more recurring units of a precursor polymer. Unless otherwise specified, a polymer or copolymer may also comprise a “terpolymer” or a “tetrapolymer” which generally refer to polymers that comprise three, four, or more different recurring monomer units. The term “polymer” as used herein is intended to include both the acid form of the polymer as well as its various salts. Polymers may be amphoteric in nature, that is, containing both anionic and cationic substituents, although not necessarily in the same proportions.

[0121] As used herein, "emulsion polyacrylamide (EPAM)” refers to an emulsion polymer in which at least one polymer is an acrylamide containing polymer. In some embodiments, the emulsion polyacrylamide (EPAM) comprises a small amount of water, for example less than about 12%, about 10%, about 5%, about 3%, about 2.5%>, about 2%, or about 1% by weight water, based on the total amount of all components of the emulsion polyacrylamide (EPAM).

[0122] As used herein, "emulsion polymer" generally refers to inverse emulsions (water-in-oil) in which water droplets containing the polymer are suspended in an oil phase, also termed a hydrophobic phase. In some embodiments, the emulsion polymer comprises a small amount of water, for example less than about 12%, about 10%, about 5%, about 3%, about 2.5%, about 2%, or about 1% by weight water, based on the total amount of all components of the emulsion polymer. The emulsion polymer is encapsulated in an oil bubble (droplet) called a micelle. It is held in there with surfactants. The surfactants keep the micelle surface tension greater that the surrounding water. If the water concentration is increased or the micelle is broken through agitation the polymer is released into the water and polymerization starts. In some embodiments, EPAMs may comprise ~33% active polymer, 10% oil and the remainder water and surfactants. By contrast a DP AM is 95% active, which enables more efficient transport and storage.

[0123] As used herein, "dry polymer" refers to a solid polymer in powder form, in granular form, or a combination thereof, which contains little water or is anhydrous. A non-limiting example is polyacrylamide powder, or dry polyacrylamide (DP AM), is an acrylamide-containing polymer or copolymer.

[0124] As used herein, the terms “polyacrylamide” or “PAM” generally refer to polymers and copolymers comprising acrylamide moieties, and the terms encompass any polymers or copolymers, including terpolymers, comprising acrylamide moieties, e.g., one or more acrylamide (co)polymers of acrylamide and additional monomers capable of copolymerizing with acrylamide. Furthermore, PAMs may comprise any of the polymers or copolymers discussed herein.

[0125] As used herein, the term “monomer” generally refers to nonionic monomers, anionic monomers, cationic monomers, zwitterionic monomers, betaine monomers, and amphoteric ion pair monomers.

[0126] As used herein the term "nonionic monomer” generally refers to a monomer that possesses a neutral charge. Exemplary nonionic monomers may comprise but are not limited to comprising10SUBSTITUTE SHEET (RULE 26)monomers selected from the group consisting of acrylamide (“AMD”), methacrylamido, vinyl, allyl, ethyl, and the like, all of which may be substituted with a side chain selected from, for example, an alkyl, arylalkyl, dialkyl, ethoxyl, and / or hydrophobic group. In an exemplary embodiment, a nonionic monomer may comprise AMD. In some embodiments, nonionic monomers may comprise but are not limited to comprising vinyl amide (e.g., acrylamide, methacrylamide, N-methylacrylamide, N,N- dimethylacrylamide), 4-acryloylmorpholine, maleic anhydride, N-vinylpyrrolidone, vinyl acetate, N- vinyl formamide and their derivatives, such as hydroxyethyl(methyl(acrylate CH2=CR-COO- CH2CH2OH (I) and CH2=CR-CO-N(Z1)(Z2) (2) N-substituted (methyl) acrylamide (II), R=H or Me; Z1=5-15.C alkyl; 1-3C alkyl substituted by 1-3 phenyl , phenyl or 6-12C cycloalkyl (both optionally substituted) and Z2=H; or Z1 and Z2 are each 3-10C alkyl; (II) is N-tert. hexyl, tert, octyl, methylundecyl, cyclohexyl, benzyl, diphenylmethyl or triphenyl acrylamide. Nonionic monomers include N-isopropylacrylamide, N-vinyl formamide, methacrylamide; N-alkylacrylamides, including but not limited to, N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, and N- butylacrylamide; N,N-dialkylacrylamides, including, but not limited to, N,N-dimethylacrylamide and N,N-diethylacrylamide; N-alkyl methacrylamides; alkyl acrylates; hydroxyalkyl acrylates and methacrylates, including but not limited to, hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 3- hydroxypropyl acrylate, 4-hydroxybutyl acrylate, hydroxymethyl methacrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate; dihydroxyalkyl acrylates and methacrylates, including but not limited to, 2,3-dihydroxypropyl acrylate, 3,4- dihydroxybutyl acrylate, 2,3-dihydroxypropyl methacrylate (DHPMA), and 3,4-dihydroxybutyl methacrylate; alkyl acrylates, including but not limited to, methyl methacrylate; acrylonitrile; N- vinylmethylacetamide, N-vinylmethylformamide; N-vinyl acetate, glyoxalated acrylamides, and vinyl pyrrolidone. Nonionic monomers can be combined for example to form copolymers with acrylamide.

[0127] As used herein, the term “anionic monomers” may refer to either anionic monomers that are substantially anionic in whole or (in equilibrium) in part, at a pH in the range of about 1.0 to about 10.0. The “anionic monomers” may be neutral at low pH (e.g., from a pH of about 0-1, 0-2, or 0-3) depending on the pKa values of acidic protons contained therein. Some anionic monomers are obtained in anionic form as alkali metal salts, alkaline earth metal salts, and ammonium salts, e.g., acrylic acid and sodium acrylamido tertiary butyl sulfonic acid (ATBS).

[0128] Examples of anionic monomers which may be used herein include but are not limited to those comprising acrylic, .methacrylic, maleic monomers and the like, acrylic acid, calcium diacrylate, and / or any monomer substituted with a carboxylic acid group or salt thereof. In some embodiments, anionic monomers may be substituted with a carboxylic acid group and include, for example, acrylic acid, and methacrylic acid. In some embodiments, an anionic monomer which may be used herein may be a (meth)acrylamide monomer wherein the amide group has been hydrolyzed to a carboxyl group. Said monomer may be a derivative or salt of a monomer according to other embodiments. Additional examples of anionic monomers comprise but are not limited to those comprising sulfonic acids or a sulfonic acid group, or both. In some embodiments, the anionic monomers which may be used herein may comprise a sulfonic function that may comprise, for example, 2-acrylamido-2- methylpropane sulfonic acid (acrylamido tertiary butyl sulfonic acid or “ATBS”). In some embodiments, anionic monomers may comprise organic acids. In some embodiments, anionic monomers may comprise acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamido methylpropane sulfonic acid, vinylphosphonic acid, styrene sulfonic acid and their salts such as sodium, ammonium and potassium. In other embodiments, anionic monomers may comprise acrylic acid, methacrylic acid; sulfonic acids, phosphonic acids, maleic acid, itaconic acid, vinyl sulfonic11SUBSTITUTE SHEET (RULE 26)acid, acrylamido tertiary butyl sulfonic acid (ATBS), acrylamido methanesulfonic acid, acrylamido ethanesulfonic acid, 2-hydroxy-3-acrylamide propane sulfonic acid, styrene sulfonic acid, vinyl phosphonic acid, and alkali metal salts, alkaline earth metal salts, and ammonium salts thereof. Anionic monomers can be combined for example to form a terpolymer of acrylamide , acrylic acid and acrylamido tertiary butyl sulfonic acid (ATBS). In an exemplary embodiment, one or more acrylamide (co)polymers may comprise at least one monoethylenically unsaturated monomer comprising acid groups, for example monomers that comprise at least one group selected from - COOH, SO3H, or -PO3H2. Examples of such monomers may include , but are not limited to, acrylic acid, methacrylic acid, vinyl sulfonic acid, allyl sulfonic acid or 2-acrylamido -2-methylpropane sulfonic acid, particularly preferably acrylic acid and / or 2-acrylamido-2- methylpropane sulfonic acid, and most preferred acrylic acid or the salts thereof. In an exemplary embodiment, one or more acrylamide (co)polymers, or each of the one or more acrylamide (co)polymers, may comprise acrylic acid and / or 2-acrylamido-2-methylpropanesulfonic acid or salts thereof.

[0129] As used herein, the term "cationic monomer" generally refers to a monomer that possesses a positive charge. Examples thereof include acryloyloxy ethyl trimethylammonium chloride (Q9) monomers. Cationic monomers may also be 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, methacrylamidopropyltrimethylammonitim 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.

[0130] Units

[0131] As used herein, the term “ppm” refers to parts per million on the basis of milligrams of solute per liter of aqueous solution or slurry (e.g., mg / L).

[0132] As used herein, the term “ppb” refers to parts per billion on the basis of micrograms of solute per liter of aqueous solution or slurry (e.g., jig / L).12SUBSTITUTE SHEET (RULE 26)

[0133] As used herein, the phrases “% by weight” or “% by wt” denotes pounds of dry mass of additive per dry mass of solids in the formulation, solution, or slurry, multiplied by 100%.DESCRIPTION OF THE INVENTION

[0134] This invention provides a method to remove oxygen from monomers to improve batch times for producing dry polyacrylamides (DP AM) and also for emulsion polyacrylamides (EPAM) in the polymerization process. Regarding DPAM, this novel method and design can be directly applied in e.g., tipping reactors but also other new technologies such as tube reactors. It can be applied to anionic and cationic DP AMs and more specifically to production sites around the world. In the future it can also be introduced in new facilities such as the one for tube reactors.

[0135] Currently the degassing process takes place via deep pipes inside the tipping reactor, this process is rather slow and can be made much faster by performing the degassing during monomer transfer. The production capacity can be increased up to 19% when combining with plant improvements. The increased capacity is a result of reducing the de-gassing time from the current 40- 60 min to practically zero.

[0136] In the present invention, degassing can occur in one pass by injecting nitrogen into a Venturi Injector. The kinetic energy of the monomer solution (motive force of the Venturi Injector) draws the gas, i.e., the N2 into the monomer solution. The inventive method also employs pressurized, flow rate controlled N2 into the Venturi Injector. Mathematical modeling of the process shows that the target 200 ppb level will be feasible if there is sufficient residence time and turbulence in the piping after the injector.

[0137] Pilot plant degassing unit was designed and built based on previous modeling work. The modeling results suggested that oxygen specification with one pass through can theoretically be achieved by increasing residence time, assuming the two phases are well mixed, preferably under turbulent conditions. Thus, to test this hypothesis a pilot unit was design to test different tube length and diameter configurations. The benefits of the inventive method and apparatus when scaled-up include: (i) ability to increase capacity, (ii) reduce degassing times from 40-60 min to practically zero and (ii) to save in N2 consumption.

[0138] Venturi Injector with Pressurized N2

[0139] Venturi Injectors have been used successfully for gas-liquid operations e.g., in water treatment and wastewater aeration. In absorption processes, the Venturi effect is used to pull gas into the liquid stream through a small orifice, allowing the gas to dissolve in the liquid.

[0140] This is commonly used in gas scrubbers, where the gas is removed from the exhaust stream. In desorption processes, the Venturi effect can be used to introduce a gas into a liquid stream, allowing the gas to bubble up and escape from the liquid. This is commonly used in stripping processes, where a gas is used to remove a volatile component from a liquid. Overall, the use of Venturi inductors in the industry provides an effective and efficient way of enhancing gas-liquid mass transfer in various applications.

[0141] The Venturi effect creates a vacuum, which pulls gas into the liquid stream through a small orifice, resulting in effective mass transfer. Furthermore, the vacuum created by the Venturi effects eliminates the need for mechanically induced gas flow, making the system rather low cost in terms of capital expenditure (CAPEX) and also easy to operate.13SUBSTITUTE SHEET (RULE 26)

[0142] The (N2) jet entering a liquid flow can be characterized using several variables, including the jet diameter, pipe diameter, velocity ratio, and pipe Reynolds number. An important dimensionless parameter is the jet regime parameter, which determines the efficiency of mixing. The variables that were studied with the pilot unit were pipe diameter, pipe length, monomer temperature, motive flow and N2 flow.

[0143] The present invention feeds pressurized and flow rate-controlled nitrogen into the Venturi Injector in order to increase degassing efficiency. The set-up comprised a N2 tank, a monomer feed tank with a cooling coil and a stirrer, a progressive cavity pump, the Venturi Injector, the 6 or 12 m of tubbing to add extra residence time a de-gasser, discharge tank, pressure sensors, flowmeters, rotameters and a dissolve oxygen meter to measure the DO. before and after the monomer passed through the injector.

[0144] More specifically, the present invention provides an apparatus according to FIG 1 for degassing a monomer composition, the apparatus comprising: a monomer tote bin (20) with Monomer tote bin bottom discharge valve (5) and Monomer tote bin valve (2), as well as a Test water tote bin (19) with a Test water tote bin bottom discharge valve (4) and Test water tote bin valve (1) feeding into a Tote discharge manifold (35). The manifold (35) feeds into a Transfer pump SKID (21) with Transfer pump skid valve (3). Waste is discharged into Waste tote bin (6).

[0145] The Transfer pump SKID (21) pumps liquid into Monomer feed tank with cooling coil and stirrer (22). Cooling coil is attached to Chill water control valve (11), Chill water supply valve (12), and Chill water return valve (13). Stirrer is connected to stirrer valve (36).

[0146] Monomer feed tank (22) drains through Feed tank discharge valve (15) into Progressive cavity pump (23), which is piped into Venturi Injector (25) comprising motive fluid inlet (32), Venturi Injector gas inlet (33), and Venturi Injector outlet (34).

[0147] Venturi Injector outlet (34) is connected to static mixer (26) and coil tubing (27), which feeds Degasser (hydro separator and gas vent) (28). After gas liquid separation, the degassed solution feeds through Hydro separator discharge valve (14), into Discharge tank (29) with DO probe (30). Discharge tank is equipped with Discharge tank exhaust valve (7).

[0148] Pressurized nitrogen gas is fed into the Venturi Injector gas inlet (33) from Nitrogen tank (pressurized N2 source) (24) through Nitrogen tank valve (8), Nitrogen tank pressure regulator discharge valve (17), and Nitrogen regulator valve (18).

[0149] Nitrogen flow to the discharge tank (29) is controlled by Discharge tank N2 feed valve (10). Nitrogen flow to the Venturi Injector is controlled by Nitrogen valve to the gas flowmeter (9). N2 needle valve (16) controlled the rate of flow through Gas flowmeter (31).LEGEND( 1 ) Test water tote bin valve(2) Monomer tote bin valve(3) Transfer pump skid valve(4) Test water tote bin bottom discharge valve(5) Monomer tote bin bottom discharge valve(6) Waste tote bin14SUBSTITUTE SHEET (RULE 26)(7) Discharge tank exhaust valve(8) Nitrogen tank valve(9) Nitrogen valve to the gas flowmeter( 10) Discharge tank N2 feed valve(11) Chill water control valve(12) Chill water supply valve(13) Chill water return valve(14) Hydro separator discharge valve(15) Feed tank discharge valve(16) N2 needle valve(17) Nitrogen tank pressure regulator discharge valve(18) Nitrogen regulator valve(19) T est water tote bin(20) Monomer tote bin(21) Transfer pump SKID(22) Monomer feed tank with cooling coil and stirrer(23) Progressive cavity pump(24) Nitrogen tank (pressurized N2 source)(25) Eductor (Venturi Injector)(26) Static mixer(27) Coil tubing(28) Degasser (hydro separator and gas vent)(29) Discharge tank(30) Dissolved oxygen (DO) probe(31) Gas flowmeter(32) Eductor (Venturi Injector) motive fluid inlet(33) Eductor (Venturi Injector) gas inlet(34) Eductor (Venturi Injector) outlet(35) Tote discharge manifold(36) Stirrer valve1

[0150] The methods, compositions, and apparatus illustratively disclosed herein suitably may be : practiced in the absence of any element which is not specifically disclosed herein and / or any element1 specifically disclosed herein. Exemplary embodiments of the invention and its advantages are further disclosed in the following examples.EXAMPLES

[0151] The examples provided herein are for illustrative purposes so that the invention may be more fully understood. These examples should not be construed as limiting the invention in any way.Example 1: Degassing test unit design and degassing procedure

[0152] DEGASSING TEST UNIT DESIGN15SUBSTITUTE SHEET (RULE 26)

[0153] The inventive apparatus for one-pass deoxygenation of a monomer solution contained a N2 tank, a monomer feed tank with a cooling coil and a stirrer, a progressive cavity pump, a Venturi Injector, a 6 m or 12 m of tubing coil to add extra residence time, a degasser, a discharge tank, a dissolved oxygen (DO) meter to measure the DO before and after the monomer passed through the Venturi Injector (eductor), pressure sensors, flowmeters, rotameters, and additional components according to the diagram in FIG 1.

[0154] Exemplary CAD renderings of different views of the inventive degassing test unit are shown in FIGS 2-3. Exemplary images of different views of the degassing test unit pilot layout as built in Aberdeen, USA are shown in FIGS 4-7.

[0155] SIMPLIFIED DEGASSING PROCEDURE

[0156] A simplified experimental procedure consisted of the following steps:

[0157] (A) Pump a monomer solution into the monomer feed tank and determine the initial DO;

[0158] (B) Start stirring and cooling the monomer to the desired temperature (i.e., a temperature low enough to prevent polymerization)

[0159] (C) Set the desired N2 flow rate;

[0160] (D) Set the desired motive flow rate;

[0161] (E) Start pumping the monomer solution through the system;

[0162] (F) Measure the final DO reading of the degassed monomer solution after one pass;

[0163] (G) The N2 flow rate, motive flow rate, tubing inner diameter, and tubing length can be adjusted and the process repeated if necessary to achieve a target DO content of < 500 ppb or a preferred target DO content of < 200 ppb.

[0164] (H) Degassed monomer solution may be (i) recirculated through the degassing system in a second (or third, fourth, etc.) pass, (ii) stored in a holding tank, preferably under a N2 atmosphere, or (iii) subjected to polymerization conditions.

[0165] DEGASSING PROCEDURE FOR AN AQUEOUS SOLUTION

[0166] A full experimental procedure consisted of the following steps using the apparatus depicted in FIG I:

[0167] 1. TEST WATER RUN

[0168] 1.1. Connect all flexible hoses as shown in the Monomer Solution De-gas test Rig Flowsheet.

[0169] 1.2. Ensure all valves are in the closed position.

[0170] 1.3. Connect hose from Test Water Tote Bin (19) to the Tote Discharge Manifold (35).

[0171] 1.4. Connect hose from Tote Discharge Manifold to the Transfer Pump Skid (21) Inlet.

[0172] 1.5. Connect hose from Transfer Pump Skid (21) outlet to the Monomer Feed Tank (22).

[0173] 1.6. Open Test Water Tote Bin Bottom Discharge Valve (4).

[0174] 1.7. Open Valve (1) on the Tote Discharge Manifold (35).

[0175] 1.8. Open Valve (3) on the Transfer Pump Skid (21) .16SUBSTITUTE SHEET (RULE 26)

[0176] 1.9. Ensure the Test Water Tote Bin (19) is vented.

[0177] 1.10. Start the Transfer Pump Skid (21).

[0178] 1.11. Fill Monomer Feed Tank (22) to desired level and stop the pump.

[0179] 1.12. Open Feed Tank Discharge Valve (15).

[0180] 1.13. Open Hydro Separator Discharge Valve (14).

[0181] 1.14. Open Nitrogen Tank Valve (8).

[0182] 1.15. Set desired pressure with Nitrogen Tank Pressure Regulator Discharge Valve (17).

[0183] 1.16. Open Regulator Valve (18).

[0184] 1.17. Open N2 Manifold Valve (9) to the Gas Flowmeter.

[0185] 1.17.1. Adjust N2 flow rate using Flowmeter Needle Valve (16) located on the bottom of the Flowmeter.

[0186] 1.17.2. N2flow rate Scale is 10 - 100 SCFH; 4.72 L / min - 47.2 L / m

[0187] 1.18. Open N2 Manifold Valve (10) to blanket the Discharge Tank (29).

[0188] 1.18.1. Close after 30 seconds.

[0189] 1.19. Set desired frequency on the pump variable frequency drive (VFD) and press start.

[0190] 1.20. Press Stop on VFD to stop the pump.

[0191] 2. FEED TANK CHILL WATER CONTROL

[0192] 2.1. Connect Chill Water Return Booster Pump to the Feed Tank Cooling Coil Return hoses.

[0193] 2.1.1. Chill Water flow is from Feed Tank Cooling Coil to Chill Water Return Valve (13).

[0194] 2.2. Open Chill Water Supply Valve (12) and Chill Water Return Valve (13)

[0195] 2.3.1Control chill water with Chill Water Control Valve Control Valve (11) above the Monomer Feed Tank (22).

[0196] 2.4. Open air supply valve to the Feed Tank Mixer pneumatic motor to circulate water in the Feed Tank.

[0197] 3. DISCHARGE TANK EMPTYING

[0198] 3.1. If completing a Monomer Solution Test.

[0199] 3.1.1. Connect hose from Transfer Pump Skid (21) to top of Waste Tote Bin (6)

[0200] 3.2. If Test Water is to be re-used for calibration

[0201] 3.2.1. Connect hose from Transfer Pump Skid (21) to Test Water Tote Bin (19) or Monomer Feed Tank (22).

[0202] 3.3. Open valve (7).

[0203] 3.4. Start the Transfer Pump Skid (21).

[0204] 3.5. When transfer is completed stop the pump and close valve (7).SUBSTITUTE SHEET (RULE 26)

[0205] 4. MONOMER DEGASSING TEST OPERATION.

[0206] 4.1. Ensure all valves are in the closed position.

[0207] 4.2. Connect hose from Monomer Tote Bin (20) to the Tote Discharge Manifold (35).

[0208] 4.3. Connect hose from Transfer Pump Skid (21) outlet to the Monomer Feed Tank (22).

[0209] 4.4. Open Monomer Tote Bin Bottom Discharge Valve (5).

[0210] 4.5. Open Valve (2) on the Tote Discharge Manifold (35).

[0211] 4.6. Open Valve (3) on the Transfer Pump Skid (21).

[0212] 4.7. Ensure the Monomer Tote Bin (20) is vented.

[0213] 4.8. Start the Transfer Pump Skid (21).

[0214] 4.9. Fill Monomer Feed Tank (22) to desired level and stop the pump.

[0215] 4.10. Close Monomer Tote Bin Bottom Discharge Valve (5).

[0216] 4.11. Open Feed Tank Discharge Valve (15).

[0217] 4.12. Open Hydro Separator Discharge Valve (14).

[0218] 4.13. Open Nitrogen Tank Valve (8).

[0219] 4.14. Set desired pressure with Nitrogen Tank Pressure Regulator Discharge Valve (17).

[0220] 4.15. Open N2 valve (9) to the Gas Flowmeter (31).

[0221] 4.15.1. Adjust flow using needle valve (16) located on the bottom of the Flowmeter (31).

[0222] 4.15.2. N2flow rate Scale is 10 - 100 SCFH; 4.72 L / min - 47.2 L / m

[0223] 4.16. Open N2 Discharge Tank Feed Valve (10) to blanket the Discharge Tank (29).

[0224] 4.17. Set desired frequency on the VFD (located on the wall under the Disconnect) and press start.

[0225] 5. IN CASE OF POLYMERIZATION

[0226] 5.1. Polymerization in the line is a rare occurrence. If polymerization is observed, connect Air Sparge Line to Feed Tank Mixer Air Supply line.

[0227] 5.2. Place Air Line open end into the tank to introduce oxygen into the solution.

[0228] 5.3. In case the polymerization is excessively exothermic.

[0229] 5.3.1. Open Test Water Tote Bin Valve (1) on the Discharge Manifold (35).

[0230] 5.3.2. Place hose from Transfer Pump Skid (21) in tank and secure hose.

[0231] 5.3.3. Start Transfer Pump.

[0232] 6. WATER FLUSH AFTER MONOMER TEST

[0233] 6.1. When the monomer test is complete or the line must be broken, flush the system with water.

[0234] 6.2. Close Chill Water Supply Valve (12) and Chill Water Return Valve (13).18SUBSTITUTE SHEET (RULE 26)

[0235] 6.3. Empty all monomer out of the Feed Tank (22) using the Progressive Cavity Pump.

[0236] 6.4. Follow “Discharge Tank Emptying procedure”.

[0237] 6.5. When transfer is completed stop the pump and close Discharge tank Exhaust Valve (7).

[0238] 6.6. Ensure hose from Test Water Tote Bin (19) to the Tote Discharge Manifold (35) is connected.

[0239] 6.7. Connect hose from Transfer Pump Skid (21) outlet to the Monomer Feed Tank (22).

[0240] 6.8. Open Test Water Tote Bin Bottom Discharge Valve (4). Open Valve (1) on the ToteDischarge Manifold (35).

[0241] 6.9. Open Valve (3) on the Transfer Pump Skid.

[0242] 6.10. Ensure the Test Water Tote Bin (19) is vented.

[0243] 6.11. Start the Transfer Pump Skid (21).

[0244] 6.12. Fill Feed Tank to desired level and stop the pump.

[0245] 6.13. Follow the steps in 3. Test Water Run to fill the Monomer Feed Tank (22)

[0246] 6.14. Flush until the Monomer Feed Tank (22) is empty at 60 Hz frequency on the VFD

[0247] 6.15. Follow again the procedure for 5. Discharge Tank Emptying into the Waste Tote Bin (6).

[0248] 6.15.1. Leave valve (2) open to flush line to the Monomer Tote Bin (20).

[0249] 6.16. Close Chill Water Supply Valve (12) and Chill Water Return Valve (13)Example 2: Modeling of DO as a function of pipe length

[0250] Modeling of the effect of tubing coil length (27) (i.e., pipe length) on final DO content of a degassed aqueous monomer, solution was performed for the degassing test unit design according to Example 1. A graph of modeling results is shown in FIG 8.

[0251] Modeling results indicate that final DO content of a solution is predicted by modeling to be■ 1 strongly correlated with length of the coiled tube downstream of N2 jet injection in the Venturi Injector (25). It was rationalized from these results that residence time of the gas-liquid mixture in the tubing between Venturi Injector (25)and degasser (28) would allow for more efficient mass action of DO between the liquid phase and the gas phase and would also allow for more time N2 and O2 to react to form nitric oxide. Nitric oxide is a gas phase product of deoxygenation with N2, and is separated from the aqueous solution at the degasser, along with N2, O2, and other volatile components of the gas / liquid mixture. It was rationalized from these modeling results that longer tubing would allow for longer residence times and allow for longer contact between N2 and 02, causing higher degassing efficiency.19SUBSTITUTE SHEET (RULE 26)Example 3: Pilot trial degassing of a water-glycol solution in one pass

[0252] Pilot trial one pass degassing of a water-glycol solution was performed with the aim of evaluating the inventive degassing system with a safer motive flow than the monomer mixture. Degassing was performed according to Example 1.

[0253] Several variables were adjusted to determine the relative impact of variance on final Do content after one pass, which was used as a metric for degassing efficiency. Motive flow rate was varied from 2.3-10.2 L / min. Initial glycol solution temperature was varied from -1.1 °C to 5.5 °C. Coil tubing length was 6 m or 12 m. Coil tubing inner diameter was varied from 4.6-10.9 mm. N2 flow rate was varied from 50-100 standard cubic feet per hour (SCFH). Experimental conditions and results after one pass are shown in Table 1.

[0254] Table 1: Results for degassing of a water-glycol solution.20SUBSTITUTE SHEET (RULE 26)

[0255] Results indicate that the inventive method for deoxygenation effectively reduced DO content of a glycol-water solution from greater than 10 ppm to 1.570-0.34 ppm, frequently less than the target of 500 ppb after one pass. The most effective deoxygenation trials resulted in 34 ppb, 90 ppb, and 201 ppb. These results match or outperform the preferred target DO content of 200 ppb after one pass.

[0256] It was surprisingly found from these results that coil tube length was only weakly correlated with degassing efficiency. Final DO contents well below 500 ppb, as low as 201 ppb, were observed using the shorter tubing length (e.g., 6 m). These results are surprisingly inconsistent with modeling results of Example 2, which predicted that tube length and degassing efficiency would be strongly correlated. By contrast, these results of Example 3 suggest that motive flow rate and tubing inner diameter have the highest impact on final DO content.

[0257] These results provide initial proof of concept that the inventive method and apparatus for is highly effective for degassing aqueous solutions after one pass. The main conclusion drawn from these results was that a tube length of 6 m seemed to be enough; therefore, the importance of extra 6 m was not as relevant as initially hypothesized. The most important parameters seemed to be motive flow rate and tube diameter.

[0258] Without being bound to theory, these results point to the fact that ensuring a high Reynolds number is crucial for the effectiveness of the system. Higher Reynolds numbers are indicative of less laminar and more turbulent flow. The results strongly suggest that achieving an optimally high Reynolds number for the Venturi Injector will be critical for production scale degassing of monomer solutions.Example 4: Pilot trials for degassing of a monomer mixture in one pass

[0259] Pilot trial one pass degassing of an aqueous monomer solution (acrylamide, 38 wt. % active) was performed with the aim of evaluating the inventive degassing system. The monomer mixture is representative of the production in an industrial plant. Degassing was performed according to Example 1.

[0260] Several variables were adjusted to determine the relative impact of variance on final Do content after one pass, which was used as a metric for degassing efficiency. Motive flow rate was varied from 5.2-11.9 L / min. Initial glycol solution temperature was from -1.1 °C or 3.5 °C. Coil tubing length was 6 m or 12 m. Coil tubing inner diameter was varied from 7.7 mm or 10.9 mm. N2 flow rate was 80 or 100 standard cubic feet per hour (SCFH). Experimental conditions and results after one pass are shown in Table 2.

[0261] Foaming was observed in several of the runs, specifically in those where N2 flowrate was high. This fact may have affected the DO. readings; however, the trends are expected to be reliable. The measurement of N2 flow was not accurate for the last three experiments in Table 2, reported values correspond to the experimental design and not to the actual measured flow.

[0262] Table 2: Results for monomer mixture (aqueous acrylamide, 38 wt. % active)21SUBSTITUTE SHEET (RULE 26)

[0263] Results indicate that the inventive method for deoxygenation effectively reduced DO content of an aqueous monomer solution from greater than 13 ppm to 1.7-0.41 ppm, frequently less than the target of 500 ppb after one pass. These results strongly suggest that achieving the preferred target DO content of 200 ppb after one pass is very likely possible.

[0264] STATISTICAL ANALYSIS OF DEGASSING RESULTS

[0265] A statistical analysis of all the results was performed. A graph of the statistical effect summary of main parameters on DO content is shown in FIG 9. Longer bars indicate a greater effect on final DO content. Results of the effect summary indicate that the most relevant variable is motive flow, followed by tube inner diameter. The least relevant variable was tube length.

[0266] These results are consistent with the surprising trends observed for deoxygenation of glycol- water and provide further confirmation of the surprising results observed in water-glycol experiments of Experiment 3, demonstrating that coil tube length is less important for efficient degassing. The most effective deoxygenation trial was achieved with a 6 m tube length and resulted in a final DO of 412 ppb. These results are surprisingly inconsistent with modeling results of Example 2, which predicted that tube length and degassing efficiency would be strongly correlated.

[0267] These results suggest that residence time (connected to tube length) is less important than originally suggested by modeling. More important variables seem to be motive flow, followed by tubing ID, followed by N2 flow rate. Venturi Injector motive flow, which causes vacuum suction, at 3 gpm gives only a few ounces of vacuum. Pressurization of N2 into the Venturi Injector causes finely divided N2 bubbles and atomization (smaller bubbles, more surface area to react N2 with 02). This reason why N2 pressurization has a dramatic effect on efficiency of process.

[0268] Without being bound to theory,1these results point to the fact that ensuring a high Reynolds number (by employing high motive flow and pressurized N2) is crucial for the effectiveness of the system. Higher Reynolds numbers are indicative of less laminar and more turbulent flow. Using a larger tubing ID provides greater volume for more efficient mixing due to the turbulent flow imparted by the high motive flow and pressurized N2 into the Venturi Injector. The results strongly suggest that achieving an optimally high Reynolds number for the Venturi Injector will be critical for production scale degassing of monomer solutions.

[0269] A dissolved oxygen (DO) prediction plot showing actual DO vs predicted DO is shown in FIG 10. Results of this statistical analysis show that the selected parameters give a satisfactory description of the results.

[0270] Statistical profiles showing the effect of main parameters on DO content and degassing time are shown in FIG 11. Target levels are represented by horizontal dashed lines. Blue lines represent the boundary conditions for achieving target final DO levels (e.g., 500 bbp or lower) and pumpingSUBSTITUTE SHEET (RULE 26)times (e.g. 25 min). The steepness of each curve in the profiler figure shows how relevant each variable is The greater the slope (center black line), the greater the effect of a variable on final DO or pump time.

[0271] Results shown in FIG 11 illustrate the impact of every operational variable on the objective variables, which are DO and time to pump. These results provide further confirmation that the most relevant variable is motive flow, followed by tube inner diameter. Although the preferred target values of 200 ppb were not achieved in the tests, the motive flow maximum level of 10.2 L / min was set due to a technical limitation of the available pump. Also, for lack of pumping capacity the higher flow rates were not achievable with the smaller tube diameters. Thus, the system can be improved to obtain preferred target DO of < 200 ppb.SUBSTITUTE SHEET (RULE 26)

Claims

CLAIMSWhat is claimed is:

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 N2gas into a gas inlet of a Venturi Injector at an N2flow 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 N2gas 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. 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. 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. 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 / orfifth 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. 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. 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. 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. 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. 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 N2consumption, or(iv) any combination of (i)-(iii), compared to a conventional method of degassing a monomer composition comprising sparging N2gas through a pipe or bubbling column into a bulk monomer composition in a reactor or holding tank.

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. 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 N2source and a means of controlling a N2flow 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. 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. 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 N2into 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. 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 N2flow rate comprises a gas flowmeter and one or more N2pressure regulators, one or more N2regulator valves and / or one or more N2needle valves arranged in line between said pressurized N2source 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. 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).

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