Antifouling formulation for compressors

Abstract

Compositions and methods for preventing or reducing polymer formation and polymer deposition in equipment used in petrochemical processes are disclosed. The antifouling composition includes a combination of one or more antioxidants, one or more antipolymerization agents, one or more dispersants, and one or more solvents. A method for preventing or reducing fouling of process equipment used in industrial processes is also described. The method includes introducing an antifouling composition into the process equipment, the antifouling composition including a combination of one or more antioxidants, one or more antipolymerization agents, one or more dispersants, and one or more solvents. [Selected Figure] Figure 1

Description

[Technical Field]

[0001] The present invention relates to antifoulant compositions and their use in compressors. [Background technology]

[0002] Compressor fouling is a well-known problem in processes that use compressors, such as the cracked gas compression systems in ethylene processes. Steam cracking of hydrocarbons constitutes nearly all of the ethylene produced worldwide. Small amounts of polymers can form during the ethylene production process. These polymers are generally considered contaminants and are undesirable.

[0003] Polymer contaminants cause problems in cracked gas compression systems, which are multi-stage systems containing multiple gas compressors and intercoolers. Polymers can deposit, for example, on the internal surfaces of the compressors and intercoolers, fouling the machinery and reducing process efficiency, potentially blocking flow paths and halting production, and in severe cases damaging components.

[0004] Premature polymerization of ethylenically unsaturated monomers is the primary mechanism of polymer formation in monomer production processes, such as ethylene cracking processes. The ethylenically unsaturated monomers in these process streams are reactive and tend to polymerize via radical and Diels-Alder polymerization, forming solid deposits, especially at elevated temperatures.

[0005] Frequent soiling and the need for cleaning can be a burden on production and operational efficiency. Summary of the Invention

[0006] Compositions and methods are disclosed for reducing fouling, thereby improving the energy efficiency of the system and preventing product quality problems.

[0007] In one aspect of the present invention, an antifouling composition is disclosed, the antifouling composition comprising a combination of one or more antioxidants, one or more antipolymerization agents, one or more dispersants, and one or more solvents.

[0008] In yet another aspect of the present invention, there is provided a method for preventing or reducing fouling of process equipment used in an industrial process, comprising the steps of: introducing an antifoulant composition into the process equipment, the antifoulant composition comprising: one or more antioxidants, one or more antipolymerization agents, one or more dispersants, and A method is disclosed that includes introducing a mixture of one or more solvents.

[0009] The disclosed compositions have application in reducing or preventing fouling of process equipment in ethylene cracking processes. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a graphical representation of the effect of various antifouling compositions of the present invention on the gel time of a simulated Pygas mixture. DETAILED DESCRIPTION OF THE INVENTION

[0011] While this disclosure provides reference to embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention. Various embodiments will be described in detail with reference to the drawings, in which like reference numerals represent like parts and assemblies throughout the several views. Reference to various embodiments does not limit the scope of the appended claims. Moreover, the examples described herein are not intended to be limiting, but merely to set forth some of the many possible embodiments within the scope of the appended claims.

[0012] definition As used herein, the term "antifoulant" refers to a composition that reduces or prevents the deposition of materials such as polymers, prepolymers, oligomers, and / or other materials on "process equipment." The term can also refer to a composition that reduces or prevents the formation of radically polymerized species.

[0013] As used herein, the term "antioxidant" refers to a compound or compounds that can scavenge oxygen-centered radicals by donating a hydrogen radical (H·) to the oxygen-centered radical.

[0014] As used herein, the term "antipolymerization agent" refers to a stable free radical that is efficient at capturing or scavenging carbon-centered radicals through coupling reactions.

[0015] Antioxidants and antipolymerization agents are sometimes called polymerization "chain terminators."

[0016] As used herein, the term "process equipment" means compressor fans, impellers, pumps, valves, intercoolers, sensors, etc., associated with a process that may be affected by fouling. The term also includes a set of components in communication, such as, for example, a gas compressor in an ethylene cracking process.

[0017] As used herein, the term "process condensate" means one or more pyrolysis by-products, in addition to water, present in a petrochemical processing system. In some embodiments, the process condensate includes pygas, pygas by-products, or a mixture thereof.

[0018] As used herein, the term "pygas" is a term of art and an abbreviation for "pyrolysis gasoline." Pygas is a pyrolysis by-product that is less dense than water and is a mixture of petroleum-based products that condenses with water in the quench water tower of the dilution steam system of an industrial processing plant, such as a thermal cracking plant. Pygas is a variable mixture of hydrocarbons and other by-products, the components and amounts of which are determined by the feedstock and conditions used in pyrolysis. As dictated by context and / or unless otherwise specified, pygas includes one or more aromatic compounds and a mixture of alkanes and alkenes having at least five carbons, with the majority (i.e., greater than 50 wt%) of the alkane / alkene components being C5-C6. 12 In some embodiments, pygas is rich in benzene (e.g., 20% to 45% by weight). Pygas also contains highly reactive olefins and diolefins, such as styrene, isoprene, piperylene, cyclopentadiene, and combinations thereof. In some embodiments, pygas further comprises components such as C1-C5 organic acids. In some embodiments, pygas comprises from about 0.01% to up to about 20% by weight of pyrolysis tar, based on the total weight of the pygas-pyrolysis tar mixture, with the amount of pyrolysis tar depending on the particular equipment and feedstock used for pyrolysis. Unless otherwise specified or in context, "pygas" includes both pygas and mixtures thereof with pyrolysis tar, pygas by-products, or both.

[0019] As used herein, the term "pyrolysis tar" is a term of art and an abbreviation for "pyrolysis tar." Pyrolysis tar is a pyrolysis by-product that is denser than water and is a mixture of petroleum-based products that condense with water in the quench water tower of the dilution steam system of a pyrolysis plant. This term refers to the petroleum-based products ≥ C, including, for example, anthracene, naphthalene, phenanthrene, pyrene, chrysene, fluoranthene, etc. 12Mixtures of alkanes / alkenes and / or ≥C10 polyaromatic hydrocarbons, as well as mixtures of two or more of these, and mixtures of similar compounds with variants having a random distribution of substituents such as methyl, ethyl, and higher alkyl or alkenyl substituents, are shown.

[0020] As used herein, the term "pygas by-product" means any one or more compounds formed as a product of a chemical reaction of one or more components of pygas (including pygas-pyrolysis tar mixtures), which reaction occurs within the dilution steam system of a pyrolysis plant and which further increases the molecular weight of one or more of the reacted components. In some embodiments, the pygas by-product comprises oligomerized or polymerized residues of styrene and / or one or more unsaturated and radically polymerizable components of pygas.

[0021] As used herein, the chemical names of polymerizable species (e.g., acrylic acid, styrene, etc.) are used to refer to either the chemical species itself or its polymerized residue in one or more polymers, as dictated by the context.

[0022] As used herein, the terms "optional" or "optionally" mean that the subsequently described event or circumstance may occur but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not occur.

[0023] As used herein, the term "about" to modify the amount, concentration, volume, process temperature, process time, yield, flow rate, pressure, and the like of a material in a composition, and ranges thereof, for example, when describing embodiments of the present disclosure, refers to variations in the numerical quantity that may occur, for example, due to typical measuring and handling procedures used to manufacture a compound, composition, concentrate, or use formulation, due to inadvertent errors in these procedures, due to differences in the manufacture, source, or purity of starting materials or components used to carry out the method, and due to approximation considerations. The term "about" also encompasses amounts that differ due to degradation of a formulation having a particular initial concentration or mixture, and amounts that differ due to mixing or processing a formulation having a particular initial concentration or mixture. When modified by the term "about," the appended claims include equivalents of these quantities. Furthermore, when "about" is used to describe any range of values, unless otherwise limited by context, for example, "about 1 to 5" means "1 to 5," "about 1 to about 5," "1 to about 5," and "about 1 to 5."

[0024] As used herein, for example, when describing embodiments of the present disclosure, the term "substantially" to modify the type or amount, property, measurable amount, manner, location, value, or range of a component in a composition refers to variations that do not affect the composition, property, amount, manner, location, value, or range recited throughout in a manner that invalidates the intended composition, property, amount, manner, location, value, or range. Examples of intended properties include, by way of non-limiting example, flexibility, partition coefficient, ratio, solubility, temperature, etc., and intended values ​​include thickness, yield, weight, concentration, etc. Effects on a process modified by "substantially" include effects caused by variations in the type or amount of materials used in the process, variations in machine settings, the effect of ambient conditions on the process, etc., where the manner or degree of effect does not negate one or more intended properties or results, but is similar to considerations of approximation. When modified by the term "substantially," the appended claims include equivalents of these types and amounts of materials.

[0025] As used herein, recited ranges of values ​​should be construed as support for claims that contemplate every value within the range and recite any subranges having endpoints that are real values ​​within the recited range. As a hypothetical illustrative example, disclosure of a range of 1 to 5 herein would be deemed to support claims to any of the following ranges: 1 to 5; 1 to 4; 1 to 3; 1 to 2; 2 to 5; 2 to 4; 2 to 3; 3 to 5; 3 to 4; and 4 to 5.

[0026] Consider Disclosed herein are antifouling compositions and methods for preventing or reducing fouling in systems used, for example, in hydrocarbon pyrolysis. The antifouling compositions include a combination of components, such as one or more antioxidants, one or more antipolymerization agents, one or more dispersants, and one or more solvents. While components such as antioxidants and antipolymerization agents have been shown to be effective in preventing polymerization and fouling, either individually or in combination, the antifouling compositions are shown herein to have a greater than additive effect. In other words, the combination of components, when used together, is more effective than each individual component separately.

[0027] antioxidants The antifouling composition includes one or more antioxidants that can act, for example, on the ethylenically unsaturated monomers. The antioxidant is a compound or a blend thereof.

[0028] Exemplary antioxidants include phenolic antioxidants such as phenylenediamine and its hindered phenols, which are known to prevent the undesired polymerization of ethylenically unsaturated monomers.

[0029] In some embodiments, the phenolic antioxidant can include hindered and unhindered phenols that target ethylenically unsaturated monomers. Examples of such phenolic antioxidants are hydroquinone (HQ), butylated hydroxytoluene (BHT), TBC, 2,6 di-tert-butylphenol, and monomethyl ether of hydroquinone (MEHQ).

[0030] In some embodiments, the phenylenediamine may comprise unsubstituted phenylenediamine, N-substituted phenylenediamine, or N,N'-substituted phenylenediamine, and any combination thereof, which target ethylenically unsaturated monomers. Examples of phenylenediamines include 1,4-phenylenediamine, N,N'-dimethyl-p-phenylenediamine, N,N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N'-dibutyl-p-phenylenediamine, N-phenyl-N'-(1,4-dimethylphenyl)-p-phenylenediamine, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, and any combination thereof.

[0031] Phenylenediamines also include p- or m-phenylenediamine itself (PDA), N,N'-diprenylphenylenediamine, N,N,N',N'-tetramethyl-p-phenylenediamine, N,N'-bis-(1,4-dimethylpentyl)-phenylenediamine, N-phenyl-N'-(1,4-dimethylpentyl)p-phenylenediamine, N-phenyl-N'-(1,3-dimethylbutyl)p-phenylenediamine, N-phenyl-N-cyclohexylp-phenylenediamine, Diamines such as N,N'-dinaphthyl p-phenylenediamine, N-isopropyl-N'-phenyl p-phenylenediamine, N-aminoalkyl-N'-phenyl p-phenylenediamine, N-(2-methyl-2-aminopropyl)-N'-phenyl p-phenylenediamine, phenyl-b-isopropyl-aminophenylamine, p-hydroxydiphenylamine, p-hydroxylphenyl-b-naphthylamine, 1,8-naphthalenediamine may also be included.

[0032] Hindered phenol compounds can include o- and p-sec-butylphenol, 2,4-di-sec-butylphenol, 2,6-di-sec-butylphenol, 2,4,6-tri-sec-butylphenol, 2,4,6-trimethylphenol, butylated hydroxytoluene (BHT, also known as 2,6-tert-butyl-4-methylphenol and 2,6-tert-butyl-p-cresol), 2,6-dibutyl-4-methylphenol, hydroquinone, monomethyl ether of hydroquinone (MEHQ), 2,6-bis(1,6 dimethylethyl-4-(1-methylpropyl)phenol), b-naphthoquinone, N-phenyl-p-aminophenol, and combinations thereof.

[0033] In some embodiments, the antioxidant is selected from 1,4-phenylenediamine, its alkylated or phenyl derivatives, and combinations thereof. Exemplary alkylated or phenyl derivatives include N,N'-di-2-butyl-1,4-phenylenediamine and N-2-butyl,N'-phenyl-1,4-phenylenediamine.

[0034] In some embodiments, the antioxidant or blend thereof is present at about 0.5% to about 50% by weight of the antifouling composition, or about 1% to about 50% by weight, about 1% to about 30% by weight, about 1% to about 20% by weight, 1% to 10% by weight, 2% to about 30% by weight, about 2% to about 20% by weight, or about 2% to 10% by weight.

[0035] Antipolymerization Agent The antifouling composition also contains an antipolymerization agent. Suitable antipolymerization agents include the following chemical groups: nitroxides (e.g., di-tert-butyl nitroxide), hindered phenoxy compounds (e.g., galvinoxyl), hydrazyl compounds (e.g., diphenylpicrylhydrazyl), and stabilized hydrocarbon radicals (e.g., triphenylmethyl), and polyradicals, preferably biradicals of these types. In addition, specific precursors that generate stable free radicals in situ may be selected from the group consisting of nitrones, nitroso, thioketones, benzoquinones, and hydroxylamines.

[0036] Exemplary anti-polymerization agents include one or more of 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO), 1-hydroxy-2,2,6,6-tetramethylpiperidine (TEMPOH), 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxyl (HTMPO), 4-oxo-2,2,6,6-tetramethylpiperidinyl-1-oxyl (OTEMPO), 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine (HTMPOH), and 1-hydroxy-4-oxo-2,2,6,6-tetramethylpiperidine (OTEMPOH), or combinations thereof.

[0037] Other exemplary antipolymerization agents include 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxide, 4-ethoxy-2,2,6,6-tetramethylpiperidine-1-oxide, 4-propoxy-2,2,6,6-tetramethylpiperidine-1-oxide, 4-butoxy-2,2,6,6-tetramethylpiperidine-1-oxide, 4 4-acetate-2,2,6,6-tetramethylpiperidinol, 4-amino-2,2,6,6-tetramethylpiperidinol, 4-acetamido-2,2,6,6-tetramethylpiperidinol, 1,2,3,6-tetrahydro-2,2,6,6-tetramethylpiperidinol, bis(2,2,6,6-tetramethylpiperidinol) sebacate, 3,6-dihydro-2,2,6,6-tetramethyl-1(2H)pyridinyloxy, or combinations thereof.

[0038] In some embodiments, the antipolymerization agent is 4-hydroxy-2,2,6,6-tetramethylpiperidyl-1-oxyl.

[0039] Other suitable agents for use as antipolymerization agents are disclosed in US Pat. No. 9,399,622, which is incorporated herein by reference in its entirety for all purposes.

[0040] In some embodiments, the antipolymerization agent is present in about 0.5% to about 30% by weight of the antifouling composition, or about 1% to about 30% by weight, 1% to about 25% by weight, about 1% to about 20% by weight, 1% to about 10% by weight, 2% to about 30% by weight, about 2% to about 25% by weight, about 2% to about 20% by weight, or 2% to about 10% by weight.

[0041] Dispersants The antifoulant composition includes one or more dispersants, which can impart one or more advantageous properties to the antifoulant composition, such as increased separation of unsaturated species, resulting in a reduced degree of polymerization, and / or increased flotation of reactive species, resulting in reduced polymer buildup on equipment such as compressor interiors.

[0042] Suitable dispersants present in the antifouling composition include amides of fatty acids. Suitable fatty acids used to form the dispersants include unsaturated fatty acids, i.e., mono- or polyunsaturated long-chain acids derived from sources including, consisting essentially of, or consisting of tall oil (tall oil fatty acid, or TOFA), coconut oil, canola oil, palm kernel oil, etc. TOFA can be obtained by fractional distillation and other refining processes performed on tall oil. Tall oil or talc is obtained primarily from the pulping of softwoods as a by-product of the Kraft process for wood pulp production. Crude tall oil contains rosin, fatty acids, and fatty alcohols, sterols, and other alkyl hydrocarbon derivatives. The majority component of TOFA after refining crude tall oil typically includes oleic acid.

[0043] Diamines comprise, consist essentially of, or consist of diamines. Diamines can include compounds with at least two amine groups, including polyamines. Diamines can be primary, secondary, or tertiary. Exemplary diamines include triethanolamine (TEA), diethylenetriamine (DETA), triethylenetetraamine (TETA), tetraethylenepentamine (TEPA), and other such compounds.

[0044] Dispersants are compounds containing two or more Dispersants It can contain a blend of two or more Dispersants In some embodiments, the dispersant is a mixture of two or more dispersants in a weight ratio of about 10:1 to 1:10, or about 1:1 to 1:10, or about 1:1 to 1:2. Dispersants It may include a blend of

[0045] In some embodiments, the dispersant is a tall oil fatty acid Triethanolamine The reaction product obtained is Dispersants Dispersants can also be formed from tall oil fatty acids and tetraethylpentamine, and the resulting Dispersant is referred to herein as P2. In some embodiments, the dispersant 、P 1:P2 may be included in a ratio of about 10:1 to 1:10, or about 1:1 to 1:10, or about 1:1 to 1:2.

[0046] In some embodiments, the dispersant is present at about 50% to about 90% by weight of the antifouling composition, or 60% to 90%, 70% to about 90%, or 60% to 70% by weight of the antifouling composition.

[0047] solvent The antifouling composition also includes one or more solvents. Suitable solvents include any solvent in which the combination of the antipolymerization agent, antioxidant, and dispersant is soluble or dispersible. In some embodiments, the solvent is a water-soluble or miscible solvent, such as a glycol-based solvent. In some embodiments, the solvent is a hydrophobic solvent, such as an aromatic solvent or a paraffin-based solvent. In some embodiments, the solvent can be a mixture of a glycol-based solvent and a hydrophobic solvent.

[0048] Exemplary glycol solvents include, but are not limited to, C1-C8 glycols such as ethylene glycol, propylene glycol, diethylene glycol, and triethylene glycol, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, liquid polyethylene glycols, ethers of such glycols such as dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, and low molecular weight polypropylene glycols, and combinations thereof. Commercially available solvents such as butyl carbitol and butyl cellosolve™ can be used and are available from The Dow Chemical Company, Midland, Michigan.

[0049] Exemplary hydrophobic solvents include heavy aromatic naphtha, toluene, ethylbenzene, and the isomeric hexanes, as well as mixtures of two or more thereof.

[0050] In some embodiments, the solvent is selected from glycol, aromatic naphtha, or glycol and aromatic naphtha.

[0051] The concentration of the one or more solvents in the antifouling composition is not particularly limited. In some embodiments, the concentration of the one or more solvents may be about 10% to 50%, about 20% to 50%, or about 30% to 50%, or about 10% to 40%, or about 10% to 30%, or about 20% to 40%, or about 30% to 40% by weight of the antifouling composition.

[0052] In some embodiments, the antifouling composition comprises about 1% to about 15% by weight of an antioxidant, about 1% to about 15% by weight of an antipolymerization agent, about 50% to about 95% by weight of a dispersant, and about 10% to about 50% by weight of a solvent in the antifouling composition.

[0053] In some embodiments, the antifouling composition includes from about 1% to about 15% by weight of 1,4-phenylenediamine, alkylated or phenyl derivative, from 1% to about 15% by weight of 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxyl, from about 50% to about 95% by weight of a product of tall oil and diamine, and from about 10% to about 50% by weight of glycol and aromatic naphtha.

[0054] The amount of antifoulant composition used will vary depending on many factors, but exemplary amounts introduced into the process equipment and process condensate (either injected into the feed stream or directly into each compression stage) are from about 1 ppm to 500 ppm, or from about 5 ppm to 500 ppm, 10 ppm to 500 ppm, or from about 20 ppm to 500 ppm, or from about 30 ppm to 500 ppm, or from about 40 ppm to 500 ppm, or from about 50 ppm to 500 ppm, or from about 60 ppm to 500 ppm, or from about 70 ppm to 500 ppm, based on the antifoulant composition. , or about 80 ppm to 500 ppm, or about 90 ppm to 500 ppm, or about 100 ppm to 500 ppm, or about 5 ppm to 450 ppm, or about 5 ppm to 400 ppm, or about 5 ppm to 350 ppm, or about 5 ppm to 300 ppm, or about 5 ppm to 250 ppm, or about 5 ppm to 200 ppm, or about 5 ppm to 150 ppm, or about 5 ppm to 100 ppm, or about 10 ppm to 300 ppm, or about 10 ppm to 250 ppm, or about 50 ppm to 250 ppm, or about 50 ppm to 200 ppm.

[0055] Processes and Applications The antifoulant composition is useful for preventing or reducing polymer buildup, and in some cases, for reducing or preventing polymer formation in process equipment, such as gas compressors used in ethylene production processes. The antifoulant composition may also be useful in other similar applications and other equipment. For example, the antifoulant composition may be used in any process where process equipment comes into contact with ethylenically unsaturated monomers, such as ethylene cracking gas processes. Another application is ethylene and acrylonitrile quench water systems. The antifoulant composition may be used in ethylene dilution steam generators and acrylonitrile purification systems. Many polymer processes have monomer recovery systems that are subject to fouling and are excellent target applications for the antifoulant composition. Process strippers and wastewater strippers used in petrochemical processes, such as styrene, butadiene, acrylonitrile, and ethylene processes, are potential applications for the antifoulant composition. In some embodiments, ethylene acid gas scrubbers and butadiene solvent recovery systems are also end-use applications for the antifoulant composition. The antifoulant composition can be used in any process where process equipment experiences polymer formation and deposition on the process equipment. Potential applications for the antifouling composition include processes that consume or produce at least one of styrene, butadiene, acrylonitrile, and ethylene.

[0056] In embodiments, the antifoulant compositions can prevent polymerization and buildup of polymers on process equipment in primary rectification processes, light components rectification, non-aromatic vinyl halide rectification, process gas compression, dilution steam systems, caustic towers, quench water towers, butadiene extraction, etc. In some embodiments, the antifoulant compositions can prevent, reduce, or retard polymerization of resins and compositions containing ethylenically unsaturated species.

[0057] The antifoulant composition may be added at one or more points in the process and in one or more locations, for example, the antifoulant composition may be added directly at the intercooler or compressor, or upstream of the intercooler or at a different stage in the same compressor.

[0058] The antifoulant composition may be added continuously or intermittently to process equipment as needed to prevent or reduce fouling.

[0059] The antifoulant composition may be added by any suitable method. For example, the antifoulant composition may be added in a neat or diluted solution. In some embodiments, the antifoulant composition may be applied as a solution, emulsion, or dispersion that is sprayed, dripped, dumped, or injected into desired openings in the system, or into process equipment or process condensate. In some embodiments, cleaning oil or tempered water may be added to the antifoulant composition.

[0060] In some embodiments, the antifoulant composition may be pumped or injected into the system in a continuous manner or as a large volume flood to clean the system. The injection points may be at any or all stages of the compressor train and / or in the discharge line before each aftercooler.

[0061] The antifoulant composition is applied to process equipment to form treated process equipment. In some embodiments, the treated process equipment may be observed to have less polymer buildup on the process equipment than on process equipment without the antifoulant composition added. The reduction or prevention of polymer formation or buildup may be evaluated by any known method or test. In some embodiments, the reduction or prevention of polymer formation and buildup on the process equipment may be evaluated by measuring the time it takes for process equipment with and without the antifoulant composition to gel. The longer it takes for the process equipment to form and / or build up a gel, the more effective the antifoulant composition is at reducing polymer formation and buildup on the process equipment.

[0062] The effectiveness of the antifoulant composition can also be evaluated by measuring the time it takes for a simulated pygas mixture to gel. The simulated pygas removes any variation in pygas composition from plant to plant. The simulated pygas mixture can contain, for example, a conjugated diene (isoprene), a vinyl monomer (ethenylbenzene), a cyclopentadiene dimer, and a crosslinker (divinylbenzene). In some embodiments, the simulated pygas mixture contains 25% wt / vol conjugated diene (isoprene), 48% wt / vol vinyl monomer (ethenylbenzene), 25% wt / vol cyclopentadiene dimer, and 2% wt / vol crosslinker (divinylbenzene). In some embodiments, using the above measurements, polymer formation and solids deposition in process equipment treated with the antifoulant composition are reduced by at least 50% by weight compared to process equipment not treated with the antifoulant composition. In some embodiments, the reduction is about 50% to 100% by weight (a 100% reduction in polymer formation is the elimination of deposition), or about 50% to 95% by weight, or about 50% to 90% by weight, or about 50% to 85% by weight, or about 50% to 80% by weight, or about 50% to 75% by weight, or about 50% to 70% by weight, or about 55% to 100% by weight, or about 60% to 100% by weight, or about 65% to 100% by weight, or about 70% to 100% by weight, or about 60% to 95% by weight, or about 70% to 95% by weight, or about 60% to 90% by weight, or about 70% to 90% by weight.

[0063] In some embodiments, fouling of the treated process equipment is reduced by 50% to 100% by weight over a 24 hour period, or a 12 hour period, or a 1 hour period, compared to untreated process equipment. The longer the time period for gel formation in process equipment treated with the antifouling composition, the less or slower the buildup of polymers on the process equipment. [Example]

[0064] The following examples are intended to illustrate different aspects and embodiments of the present invention and should not be considered as limiting the scope of the present invention. It will be appreciated that various modifications and variations can be made without following the experimental embodiments described herein and without departing from the scope of the claims.

[0065] Example 1 Materials used: The simulated pygas mixture contained 25 wt / vol% conjugated diene (isoprene), 48 wt / vol% vinyl monomer (ethenylbenzene), 25 wt / vol% dimer of cyclopentadiene, and 2 wt / vol% crosslinker (divinylbenzene).

[0066] Stock solutions of solvent-free N,N'-di-Sec-butyl-1,4-phenylenediamine (PDA) and 4-hydroxy-2,2,6,6-tetramethylpiperidyl-1-oxyl (HTMPO) of known concentrations were diluted with aromatic naphtha and further diluted with a glycol-based cosolvent.

[0067] Aromatic naphtha (C10+) and butyl glycol were used as co-solvents. The solvent and co-solvent were used in equal weight percent amounts.

[0068] Three dispersants were used, namely Dispersants Type I, Type II, and Type III, and were prepared as follows.

[0069] Dispersant Type I consists of two Dispersants It is a blend of tall oil fatty acids (TOFA) and Triethanolamine (TEA) to give product 1 (P1). TOFA was mixed with tetraethylenepentamine (TEPA) and diluted with xylene to give product 2 (P2), which can be simplified as shown below: TOFA+TEA:P1 or TOFA+TEPA:P2

[0070] The ratio of P1:P2 for dispersant type I was 3.6:1.

[0071] Dispersant Type II was prepared similarly to Dispersant Type 1, except the ratio of P1:P2 was 7.8:1.

[0072] Dispersant Type III was a methacrylated copolymer (methacrylic acid C4-C18 polymer) in paraffin oil available from AftoN Chemicals as Texaco TC-8103.

[0073] A stock solution of known concentration of HTMPO in aromatic naphtha was further diluted with a glycol-based cosolvent. PDA was added to the mixture along with Dispersant Type I, II, or III. The mixture was vigorously mixed until all solids were dissolved and the solution was homogeneous.

[0074] 500 ppm of each formulation shown in Table 1 was dosed into a simulated Pygas mixture in a sealed, pressure-rated tube and mixed vigorously. Each tube was then purged with 100% nitrogen for 1 minute and tightly capped. The tubes were placed in a temperature-controlled environment with the temperature set at 130°C. The gel point, the onset of solidification of the mixture, was determined by inverting the tube and monitoring the flow. Each formulation was tested three times, and the reported data is the average of the three test results for each sample. Data is reported as the time it took for the simulated Pygas mixture to gel. After the first tube gelled, the other samples were checked every five minutes.

[0075] The formulations of the antifouling compositions with the weight percentages dosed into the Pygas mixture are shown in Table 1. The results of the time to gel for each formulation are shown in Table 1 and in Figure 1. [Table 1]

[0076] As shown in Table 1, the control experiment S1 exhibited the shortest gelation time, while S8 exhibited the longest. The addition of dispersants, PDA, and HTMPO increased the time to gel, as shown in S2, S3, and S4. The difference between S5 and S8 was related to the type of dispersant (Type III and Type I). The difference between S6 and S7 samples was due to the ratio of Type I to Type II dispersants. Using Type I dispersant increased the gelation time from 150 to 165 minutes (10%). The difference between S7 and S8 reflects the cumulative effect of the antipolymerizer, antioxidant, and dispersant. S8 exhibited the longest gelation time, which was longer than the additive effect measured by the time to gel.

[0077] The inventions illustratively disclosed herein may suitably be practiced in the absence of any element not specifically disclosed herein. Moreover, each embodiment of the invention described herein is intended to be used either alone or in combination with any other embodiment described herein, as well as modifications, equivalents, and alternatives thereof. In various embodiments, the invention suitably comprises, consists essentially of, or consists of the elements described and claimed herein. It will be recognized that various modifications and changes can be made without following the exemplary embodiments and applications illustrated and described herein and without departing from the scope of the claims.

Claims

1. 1. An antifouling composition comprising: 1% to 10% by weight of one or more antioxidants; wherein the antioxidant comprises N,N'-di-Sec-butyl-1,4-phenylenediamine; 1% to 10% by weight of one or more antipolymerization agents; wherein the antipolymerization agent comprises 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxyl; 70% to 90% by weight of one or more dispersants; wherein the dispersant is a blend of two or more dispersants, a first dispersant being a reaction product of tall oil fatty acid and triethanolamine (TEA) and a second dispersant being a reaction product of tall oil fatty acid and tetraethylenepentamine (TEPA), the blend having a mass ratio of the first dispersant to the second dispersant of 1:1 to 1:10; and one or more solvents including a combination of composition.

2. 10. Use of the composition of claim 1 to reduce or prevent fouling of process equipment in an ethylene cracking process.

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