Patent Application
20240384472
The present disclosure generally relates to the removal of lignin during the pulping process through the use of a novel drainage aid.
This background information is provided for the purpose of making information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should it be construed, that any of the preceding information constitutes prior art against the present invention.
The manufacture of paper from wood requires many complex steps, including the formation of pulp fiber from wood chips. This process typically takes place in a digester, where wood chips are cooked at high temperature with sodium sulfide and sodium hydroxide in order to break down and solubilize the lignin, so that it can be separated from the wood pulp. The most prominent by-product of the process is kraft lignin, a complex three-dimensional material based on repeating phenol propane units. The lignin and spent cooking chemicals are contained in the liquid fraction, often referred to as black liquor, of the brown stock.
Additional by-products found in the black liquor include wood pitch and hemicelluloses (low molecular weight polysaccharides). When pine is used, crude tall oil and turpentine become very important by-products.
Following the digester, the black liquor (containing organics, mostly lignin, and inorganic spent cooking chemicals) is separated from the wood pulp in a process commonly known as brown stock washing. Rotary drum washers placed in series are commonly used to wash brown stock. Generally, these drums are made up of different washing zones. The first washing step within a drum is usually dilution/thickening, where the brown stock is diluted with liquid which is cleaner than the liquid within the brown stock. After the stock is thickened on the vacuum drum, a second washing step of displacement is usually conducted. In the displacement phase, liquid which is cleaner than the mat of pulp is applied to the mat surface via showers and pulled through the pulp mat to displace the dirty liquid held within it. Kraft brown stock washing can also be conducted with variations of this washing technique. Other washing methods include pressure washers, which use pressure rather than vacuum, and belt washers, which use displacement.
Brown stock washing is important to the pulp mill operation. Digester cooking chemicals are recovered for reuse during washing. Pulp mills also burn the organics for their heating value. Bleaching, which often follows brown stock washing, is more efficient when the brown stock washers remove the most by-product solids possible.
The brown stock washing phase is also especially important environmentally. The effluent from bleaching is discharged from the mill; this effluent contains chlorinated organics, which can be toxic. Toxic substances which are currently of concern include dioxins and furans, specifically 2,3,7,8-tetradichlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran, absorbable organic halogens, and color. Increased organics removal in brown stock washing has been shown to decrease the environmental impact of bleaching.
Brown stock washing is an important aspect of pulp mill operation. Specifically, the washing of organics from pulp is becoming increasingly important. In bleached processes, enhanced organic removal would reduce bleaching chemical consumption, costs, and environmental problems associated with effluent discharge of chlorinated organics. In unbleached processes, enhanced organics removal in washing should decrease runnability problems associated with excess lignin in pulp, such as reduced retention aid performance. Drainage aids are added at the brown washing stage only to avoid carryover. The drainage aid disclosed herein may be added beyond the brown washing stage for the fiber line of the papermaking process.
The preceding information should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 CFR § 1.56(a) exists.
Brown stock washing is a complex, dynamic process in which dirty wash water or weak black liquor (dissolved organic and inorganic material obtained from the pulp cooking process) is separated from pulp fibers. The use of material balance techniques is of great importance to identify potential problems and determine how well the system is operating. The kraft pulping industry was the first known to combine pulp washing with the recovery of materials used and produced in the wood cooking process. The motivation behind materials recovery is economic, and more recently, environmentally driven. The chemicals used in the kraft process are expensive as compared to those used in the sulfite process. For the kraft process to be economically viable, it is imperative that a very high percentage of the cooking chemicals be recovered. To reach such high efficiency, a variety of washing systems and monitoring parameters have been developed. Antifoam additives and processing aids have also played an important role in increasing washing effectiveness. Antifoam materials help attain washing effectiveness by preventing entrapped air from forming in the system, which allows for an easier, unimpeded flow of filtrate through the screens and washers.
One aspect of the invention pertains to a drainage aid, said aid comprising a sodium lauryl ether sulfate (SLES); wherein said sodium lauryl ether sulfate (SLES) is present in an amount of about 1%-70 wt. % (or 5-50%). In some embodiments, said nonionic surfactant comprises tridecyl alcohol ethoxylate. In yet further embodiments, said tridecyl alcohol ethoxylate is present in an amount of about 20-80 wt. % (or 30-60 wt. %).
A further aspect of the invention pertains to a drainage aid, said aid comprising one or more nonionic surfactants and optionally a sulfonated anionic surfactant or an amphoteric surfactant. In some embodiments, said nonionic surfactant comprises tridecyl alcohol ethoxylate. In yet further embodiments, said tridecyl alcohol ethoxylate is present in an amount of about 20-80 wt. % (or 30-60 wt. %).
Another aspect of the invention pertains to a method for treating pulp, said method comprising adding sodium lauryl ether sulfate (SLES), and optionally one or more component(s) chosen from a sulfonated anionic surfactant (e.g., alkyl (C10-16) benzenesulfonic acid), a hydrotrope, a nonionic surfactant, and di-(2-ethylhexyl) sodium sulfosuccinate, a defoamer, a preservative, and a solvent, or a combination thereof to untreated pulp to obtain treated pulp;
In some embodiments, said nonionic surfactant comprises tridecyl alcohol ethoxylate. In yet further embodiments, said tridecyl alcohol ethoxylate is present in an amount of about 20-80 wt. % (or 30-60 wt. %).
Another aspect of the invention pertains to a method for treating pulp, said method comprising adding one or more nonionic surfactants and optionally a sulfonated anionic surfactant or an amphoteric surfactant (e.g. dimetyltertadecylamine oxide), to untreated pulp to obtain treated pulp;
In some embodiments, said nonionic surfactant comprises tridecyl alcohol ethoxylate. In yet further embodiments, said tridecyl alcohol ethoxylate is present in an amount of about 20-80 wt. % (or 30-60 wt. %).
Various embodiments are described below with reference to the drawings in which like elements generally are referred to by like numerals. The relationship and functioning of the various elements of the embodiments may better be understood by reference to the following detailed description. However, embodiments are not limited to those explicitly described below. It should be understood that the drawings are not necessarily to scale, and in certain instances details may have been omitted that are not necessary for an understanding of embodiments disclosed herein, such as-for example-conventional fabrication and assembly.
The methods and systems described herein are related to treatment of brown stock as well as dosing the drainage aids disclosed herein during the O2 stage (e.g., at the oxygen delignification stage) or at the bleaching stage (e.g., at one or more extraction steps) of the fiber line (see, e.g.,
Generally, brown stock is washed to remove solids (e.g., black liquor solids) and soluble lignins from the unbleached pulp prior to, for example, oxygen delignification, bleaching, and/or feeding the pulp to a papermaking process, and to reduce conductivity of the pulp mat to improve efficiency of downstream bleaching. Additionally, brown stock washing helps reduce soda loss in brown stock processing, which generally promotes efficiency in processing as related to soda consumption.
Brown stock washers include, but are not limited to, chemiwashers, displacement drum washers, horizontal belt washers, rotary pressurized drum washers, compaction baffle washers, twin-roll presses, and screw presses. Depending on the washer used in the brown stock washing process, different variables may be controlled or monitored to optimize the process. For example, in a chemiwasher, the feed consistency, air entrainment, forming and stage vacuums, stage shower flows, wire speed, liquor solids levels, and final dilution may be monitored.
The pulp in the brown stock may be derived from hardwoods, softwoods, or a mixture thereof. The methods described herein are effective in treating brown stock containing hardwood, softwood, or mixtures thereof. Generally, brown stock washing is performed via a brown stock washing process that comprises a brown stock being delivered (e.g., flowed) to a brown stock washer drum rotating at a brown stock washer drum speed. The brown stock comprises pulp slurry, and the pulp slurry is taken up by the rotating brown stock washer drum. Treatment in the form of, among others, drainage aid, defoamer, or both drainage aid and defoamer are delivered to the pulp slurry via one or more pumps. The brown stock washing process may be performed in stages (e.g., delivery of one treatment, followed by delivery of a second treatment that may be the same or different) on a plurality of brown stock washer drums. The brown stock washing process may be repeated one or more times. Generally, after completing the brown stock washing process, the pulp slurry undergoes an oxygen delignification process before proceeding to a bleaching plant for bleaching. In certain embodiments of the methods provided herein, the pulp is treated with the drainage aid during the brown stock washing stage, the oxygen delignification stage and/or the bleaching stage so as to minimize bleaching costs (e.g., minimize chlorine dioxide consumption and/or hydrogen peroxide consumption).
One aspect of this invention relates to an improved pulp washing process comprising at least one oxygen delignification stage wherein the purified pulp from the oxygen delignification stage is treated with the drainage aid prior to or during its wash cycle.
Another aspect of this invention relates to an improved pulp washing process comprising at least one bleaching stage comprising at least one bleaching step (for example, where D is a step in which pulp is treated with a bleaching agent comprising chlorine dioxide in the presence of a weak base at pH from about 3.5 to about 6.5) and at least one extraction step (for example, where E is an extraction step E can be E, Eo, Ep or Eop) wherein the pulp from the extraction step is treated with the drainage aid prior to or during its wash cycle. The extraction step E is defined as treating the pulp in the presence of a base. The extraction step Eo is defined as treating the pulp with oxygen in presence of a base. The extraction step Ep is defined as treating the pulp with peroxide in presence of a base. The extraction step Eop is defined as treating the pulp with oxygen and peroxide in presence of a base.
The following definitions are provided to determine how terms used in this application, and in particular, how the claims are to be construed. The organization of the definitions is for convenience only and is not intended to limit any of the definitions to any particular category.
The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein.
Any ranges given either in absolute terms or in approximate terms are intended to encompass both, and any definitions used herein are intended to be clarifying and not limiting. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges (including all fractional and whole values) subsumed therein.
Any method disclosed herein may comprise, consist of, or consist essentially of any method step disclosed herein or any combination of two or more of the method steps disclosed herein.
The transitional phrase “consisting of” excludes any element, component, ingredient, and/or method step not specified in the claim.
The transitional phrase “consisting essentially of” limits the scope of a claim to the specified elements, components, ingredients and/or steps, as well as those that do not materially affect the basic and novel characteristic(s) of the claimed invention.
“Contacting” as used herein in the context of application of the drainage aid prepared according to the methods disclosed herein, refers to combining said drainage aid with pulp slurry.
“Consisting essentially of” means that the methods and compositions may include additional steps, components, ingredients or the like, but only if the additional steps, components and/or ingredients do not materially alter the basic and novel characteristics of the claimed methods and compositions.
The following solvents and hydrotropes may be used in the additives described herein.
Representative solvents include benzyl acetate, benzyl alcohol, methyl benzyl alcohol, alpha phenyl ethanol, benzyl benzoate, benzyloxyethanol, ethylene glycol phenyl ether, propylene glycol phenyl ether, amyl acetate, amyl alcohol, butanol, 3-butoxyethyl-2-propanol, butyl acetate, n-butyl propionate, cyclohexanone, diacetone alcohol, diethoxyethanol, diethylene glycol methyl ether, diisobutyl carbinol, diisobutyl ketone, dimethyl heptanol, dipropylene glycol tert-butyl ether, ethanol, ethyl acetate, 2-ethylhexanol, ethyl propionate, ethylene glycol methyl ether acetate, hexanol, isobutanol, isobutyl acetate, isobutyl heptyl ketone, isophorone, isopropanol, isopropyl acetate, methanol, methyl amyl alcohol, methyl n-amyl ketone, 2-methyl-1-butanol, methyl ethyl ketone, methyl isobutyl ketone, 1-pentanol, n-pentyl propionate, 1-propanol, n-propyl acetate, n-propyl propionate, propylene glycol ethyl ether, tripropylene glycol methyl ether, tripropylene glycol n-butyl ether, diethylene glycol n-butyl ether acetate, diethylene glycol monobutyl ether, ethylene glycol n-butyl ether acetate, ethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, propylene glycol monobutyl ether, ethyl 3-ethoxypropionate, 2,2,4-Trimethyl-1,3-Pentanediol Monoisobutyrate, diethylene glycol monohexyl ether, ethylene glycol monohexyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol methyl ether acetate, ethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, methanol, propylene glycol methyl ether acetate, propylene glycol monomethyl ether, diethylene glycol monopropyl ether, ethylene glycol monopropyl ether, dipropylene glycol monopropyl ether and propylene glycol monopropyl ether.
The term “hydrotrope” as used in the methods and compositions herein refers a hydrotrope coupler that does not react with the other components of the brown stocking aid disclosed herein or negatively affect the performance properties of the brown stocking aid. As used herein “hydrotrope” refers to a compound that solubilizes hydrophobic compounds in aqueous solutions by means other than micellar solubilization.
Representative classes of hydrotropes which can be employed include anionic surfactants such as alkyl sulfates and alkane sulfonates, linear alkyl benzene or naphthalene sulfonates, secondary alkane sulfonates, alkyl ether sulfates or sulfonates, dialkyl sulfosuccinic acid esters, sugar esters (e.g., sorbitan esters), amine oxides (mono-, di-, or tri-alkyl) and C8-C10alkyl glucosides. Preferred coupling agents for use in the present invention include n-octanesulfonate, available as NAS 8D from Ecolab Inc., n-octyl dimethylamine oxide, and the commonly available aromatic sulfonates such as the alkyl benzene sulfonates (e.g. xylene sulfonates) or naphthalene sulfonates, aryl or alkaryl phosphate esters or their alkoxylated analogues having 1 to about 40 ethylene, propylene or butylene oxide units or mixtures thereof. Other preferred hydrotropes include nonionic surfactants of C6-C24alcohol alkoxylates (alkoxylate means ethoxylates, propoxylates, butoxylates, and co-or-terpolymer mixtures thereof) (preferably C6-C14alcohol alkoxylates) having 1 to about 15 alkylene oxide groups (preferably about 4 to about 10 alkylene oxide groups); C6-C24alkylphenol alkoxylates (preferably C8-C10alkylphenol alkoxylates) having 1 to about 15 alkylene oxide groups (preferably about 4 to about 10 alkylene oxide groups); C6-C24alkylpolyglycosides (preferably C6-C20alkylpolyglycosides) having 1 to about 15 glycoside groups (preferably about 4 to about 10 glycoside groups); C6-C24fatty acid ester ethoxylates, propoxylates or glycerides; and C4-C12mono or dialkanolamides.
As used herein, the term “wt. %” when mentioned with respect to the amount of an ingredient (e.g., SLES, hydrotrope, etc.) in a drainage aid or other composition refers to the weight percent of that individual ingredient relative to the total wt. % of drainage aid added to the papermaking process. For example, a drainage aid comprising sodium lauryl ether sulfate (SLES) present in an amount of about 1 wt. % to about 70 wt. % would be based on the total weight of the drainage aid composition added to the papermaking process whether as a pre-mixed composition, or whether individual ingredients are separately added at different stages of the papermaking process.
In the event that the above definitions or a description stated elsewhere in this application is inconsistent with a meaning (explicit or implicit) which is commonly used, in a dictionary, or stated in a source incorporated by reference into this application, the application and the claim terms in particular are understood to be construed according to the definition or description in this application, and not according to the common definition, dictionary definition, or the definition that was incorporated by reference. In light of the above, in the event that a term can only be understood if it is construed by a dictionary, if the term is defined by the Kirk-Othmer Encyclopedia of Chemical Technology, 5th Edition, (2005), (Published by Wiley, John & Sons, Inc.) this definition shall control how the term is to be defined in the claims.
The foregoing may be better understood by reference to the following examples, which are presented for purposes of illustration and are not intended to limit the scope of the invention.
See
Test samples: The performance of incumbent product PP10-3148 was compared with Biosoft S101 and CS460 at three dosages.
The following is a non-limiting list of embodiments encompassed by the invention:
All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
Embodiments of the present disclosure are described herein, including the best mode known to the inventors for carrying out the invention. Variations of these embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
While this invention may be embodied in many different forms, there are described in detail herein specific preferred embodiments of the invention. The present disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. All patents, patent applications, scientific papers, and any other referenced materials mentioned herein are incorporated by reference in their entirety. Furthermore, the invention encompasses any possible combination of some or all of the various embodiments mentioned herein, described herein and/or incorporated herein. In addition the invention encompasses any possible combination that also specifically excludes any one or some of the various embodiments mentioned herein, described herein and/or incorporated herein. Any information in any material (e.g., a United States patent, United States patent application, book, article, etc.) that has been incorporated by reference herein, is only incorporated by reference to the extent that no conflict exists between such information and the other statements and drawings set forth herein. In the event of such conflict, including a conflict that would render invalid any claim herein, then any such conflicting information in such incorporated by reference material is specifically not incorporated by reference herein.
The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims.
All ranges and parameters disclosed herein are understood to encompass any and all subranges subsumed therein, and every number between the endpoints. For example, a stated range of “1 to 10” should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, (e.g. 1 to 6.1), and ending with a maximum value of 10 or less, (e.g. 2.3 to 9.4, 3 to 8, 4 to 7), and finally to each number 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 contained within the range. All percentages and proportions herein are by weight unless otherwise specified.
This completes the description of the preferred and alternate embodiments of the invention.
Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.
This application claims priority to U.S. Application No. 63/503,148, filed on May 18, 2023, the contents of which are hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63503148 | May 2023 | US |
