Antifoulant formulation for compressor

Abstract

To provide a method for preventing or reducing polymer formation and polymer accumulation in equipment used in a petrochemical process.SOLUTION: A method for preventing or reducing dirt of process equipment used in an industrial process includes introducing an antifoulant composition into the process equipment. The antifoulant composition includes a combination of one or more antioxidants, one or more antipolymerization agents, one or more dispersants, and one or more solvents.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an antifoulant composition and its 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 of ethylene processes. Steam cracking of hydrocarbons constitutes nearly all of the ethylene produced worldwide. Small amounts of polymers can be formed 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 that include multiple gas compressors and intercoolers. Polymers can foul the machinery, for example by depositing on the internal surfaces of the compressors and intercoolers, resulting in inefficiencies in the process, in some cases blocking flow paths and halting production, and in severe cases, damaging parts.

[0004] Premature polymerization of ethylenically unsaturated monomers is the primary polymer formation mechanism 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 to form solid deposits, especially at high 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 systems 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, comprising a combination of one or more solvents.

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

[0010] [Figure 1] 1 is a graphical representation of the effect of various antifoulant compositions of the present invention on the gel time of a simulated pygas mixture. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Although the present 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 now 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 is not intended to 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 capable of scavenging an oxygen-centered radical 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 scavenging or scavenging carbon-centered radicals by 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, and the like, 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 mixtures 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 condense with water in the quench water tower of the dilution steam system of an industrial processing plant, such as a pyrolysis plant. Pygas is a variable mixture of hydrocarbons and other by-products, the components and amounts of the mixture being 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 of "pyrolysis tar." Pyrolysis tar is a mixture of petroleum-based products that are pyrolysis by-products that are denser than water and that condense with water in the quench water tower of the dilution steam system of a pyrolysis plant. The term refers to any mixture of petroleum-based products ... 12Mixtures of alkanes / alkenes and / or ≧C10 polyaromatic hydrocarbons, as well as mixtures of two or more of these, as well as mixtures of similar compounds with variants having random distribution of substituents such as methyl, ethyl, and higher alkyl or alkenyl substituents, are depicted.

[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) that occurs within the dilution steam system of a pyrolysis plant and that 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, chemical names of polymerizable species (e.g., acrylic acid, styrene, etc.) are used to refer either to the chemical species itself or to 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 an embodiment of the present disclosure, refers to variations in numerical quantities that may occur, for example, due to typical measuring and handling procedures used to manufacture a compound, composition, concentrate, or formulation for use, due to accidental errors in these procedures, due to differences in the purity of starting materials or components used to manufacture, source, or carry out the method, and due to approximation considerations, and the like. 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 amounts. Furthermore, when "about" is used to describe any range of values, for example, "about 1 to 5" means "1 to 5" and "about 1 to about 5" and "1 to about 5" and "about 1 to 5" unless otherwise limited by the context.

[0024] As used herein, the term "substantially" to modify the type or amount, property, measurable amount, manner, location, value, or range of a component in a composition, for example, when used in describing an embodiment of the present disclosure, refers to a variation that does 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, effects of ambient conditions on the process, etc., where the manner or degree of effect does not negate one or more intended properties or results, as well as proximate considerations. 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 1-5 herein would be deemed to support claims to any of the following ranges: 1-5; 1-4; 1-3; 1-2; 2-5; 2-4; 2-3; 3-5; 3-4; and 4-5.

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

[0027] Antioxidants The antifouling composition includes one or more antioxidants capable of acting, 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 can include unsubstituted phenylenediamine, N-substituted phenylenediamine or N,N'-substituted phenylenediamine, and any combination thereof, which targets ethylenically unsaturated monomers.Examples of phenylenediamine are 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 are also known as 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, Also included may be diamines, 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.

[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 (also known as BHT, 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 blends thereof are present at about 0.5% to about 50% by weight of the stainblocker 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 includes an antipolymerization agent. Suitable antipolymerization agents include the following groups of chemicals: 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 of nitrones, nitrosos, 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 and for all purposes.

[0040] In some embodiments, the antipolymerization agent is present at about 0.5% to about 30% by weight, 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 of the antifouling composition.

[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 thereof, and / or increased flotation of reactive species, resulting in reduced polymer build-up on equipment, such as compressor internals.

[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 that include, consist essentially of, or consist of tall oil (tall oil fatty acid, or TOFA), coconut oil, canola oil, palm kernel oil, and the like. TOFA can be obtained by rectification distillation and other refining processes carried out on tall oil. Tall oil or tarol is obtained primarily from the pulping of softwoods as a by-product of the Kraft process of 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] The diamine comprises, consists essentially of, or consists of a diamine. The diamine can include compounds having at least two amine groups, including polyamines. The diamine can be primary, secondary, or tertiary. Exemplary diamines include triethanolamine (TEA), diethylenetriamine (DETA), triethylenetetraamine (TETA), tetraethylenepentamine (TEPA), and other such compounds.

[0044] The dispersant can include a blend of two or more fatty acid amides. The two or more fatty acid amides can be different. In some embodiments, the dispersant can include a blend of two or more fatty acid amides 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.

[0045] In some embodiments, the dispersant is a reaction product of tall oil fatty acids and trimethylamine. The resulting fatty acid amide product is referred to herein as P1. The dispersant can also be formed from tall oil fatty acids and tetraethylpentamine, with the resulting fatty acid amide product referred to herein as P2. In some embodiments, the dispersant can include fatty acid amide products P1:P2 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 at 60% to 90% by weight, 70% to about 90% by weight, or at 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 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, a paraffin-based solvent, etc. 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 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 one or more solvents in the antifouling composition is not particularly limited. In some embodiments, the concentration of one or more solvents may be about 10% by weight to 50% by weight, about 20% by weight to 50% by weight, or about 30% by weight to 50% by weight, or about 10% by weight to 40% by weight, or about 10% by weight to 30% by weight, or about 20% by weight to 40% by weight, or about 30% by weight to 40% by weight.

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

[0053] In some embodiments, the antifouling composition includes about 1% to about 15% by weight of 1,4-phenylenediamine, alkylated or phenyl derivative, 1% to about 15% by weight of 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxyl, about 50% to about 95% by weight of a product of tall oil and diamines, and 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, or from 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 may be used in any process that has process equipment where polymers form and build up on the process equipment. Potential applications of the antifouling composition include in addition to processes that consume or produce at least one of styrene, butadiene, acrylonitrile, and ethylene.

[0056] In embodiments, the antifoulant compositions can prevent polymerization and deposition of polymers on process equipment in primary fractionation processes, light components fractionation, non-aromatic vinyl halide fractionation, process gas compression, dilution steam systems, caustic towers, quench water towers, butadiene extraction. 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 compositions 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, the antifoulant composition may be added with wash oil or tempered water.

[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 the 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 the process equipment without the addition of the antifoulant composition. The reduction or prevention of polymer formation or polymer buildup may be evaluated by any known method or test. In some embodiments, the reduction or prevention of polymer formation and polymer buildup on the process equipment may be evaluated by measuring the time it takes for the 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 polymer 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 dimer of cyclopentadiene, and a crosslinker (divinylbenzene). In some embodiments, the simulated pygas mixture contains 25% w / v conjugated diene (isoprene), 48% w / v vinyl monomer (ethenylbenzene), 25% w / v cyclopentadiene dimer, and 2% w / v crosslinker (divinylbenzene). In some embodiments, using the above measurements, polymer formation and solids deposition in process equipment treated with the antifoulant composition is reduced by at least 50% by weight compared to process equipment not treated with the antifoulant composition. In some embodiments, the reduction is from about 50% to 100% by weight (a 100% reduction in polymer formation is the elimination of deposition), or from about 50% to 95% by weight, or from about 50% to 90% by weight, or from about 50% to 85% by weight, or from about 50% to 80% by weight, or from about 50% to 75% by weight, or from about 50% to 70% by weight, or from about 55% to 100% by weight, or from about 60% to 100% by weight, or from about 65% to 100% by weight, or from about 70% to 100% by weight, or from about 60% to 95% by weight, or from about 70% to 95% by weight, or from about 60% to 90% by weight, or from 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 antifoulant composition, the less or slower the build-up of polymers on the process equipment. EXAMPLES

[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 of a conjugated diene (isoprene), 48% wt / vol of a vinyl monomer (ethenylbenzene), 25% wt / vol of a dimer of cyclopentadiene, and 2% wt / vol of a 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 with a glycol-based co-solvent.

[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 is a blend of two fatty acid amides. Tall oil fatty acid (TOFA) and trimethylamine (TEA) were combined to give product 1 (P1). TOFA was mixed with tetraethylenepentamine (TEPA) and diluted with xylene to give product 2 (P2), which is 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 that 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 co-solvent. PDA was added to the mixture along with dispersant type I, II, or III. The mixture was mixed vigorously 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, which is the onset of solidification of the mixture, was determined by turning the tube upside down and monitoring the flow. Each formulation was tested three times and the data reported are 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 5 minutes.

[0075] The stainblocker composition formulations with the weight percentages dosed into the pygas mixture are shown in Table 1. The time to gel results for each formulation are shown in Table 1 and in FIG. [Table 1]

[0076] As shown in Table 1, the control experiment S1 showed the shortest gelation time and S8 showed the longest gelation time. The addition of dispersant, PDA, and HTMPO increased the time to gel as shown by 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 lies in the ratio of dispersant type (I) to type (II). When the dispersant component was used as type (I), the gelation time increased from 150 to 165 minutes (10%). The difference between S7 and S8 represents the cumulative effect of the antipolymerization agent, antioxidant, and dispersant. S8 showed the longest time to gel. This time was longer than the additive effect measured by the time to gel.

[0077] The invention illustratively disclosed herein may suitably be implemented 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 their modifications, equivalents and alternatives. 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 may 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. A method for preventing or reducing fouling of process equipment used in an industrial process, comprising: introducing into said process equipment an antifoulant composition, said antifoulant composition comprising: one or more antioxidants, one or more antipolymerization agents; one or more dispersants, and One or more solvents The method includes introducing a combination of

2. 10. The method of claim 1, wherein said introducing comprises injecting a cleaning oil into said antifoulant composition.

3. 3. The method of claim 1 or 2, wherein said introducing comprises injecting said antifoulant composition with tempered water.

4. The method according to any one of claims 1 to 3, wherein the industrial process is an ethylene cracking process.

5. 5. The method of any one of claims 1 to 4, wherein the antifoulant composition comprises from about 1% to about 15% by weight of an antioxidant, from about 1% to about 15% by weight of an antipolymerization agent, from about 50% to about 95% by weight of a dispersant, and from about 10% to about 50% by weight of a solvent in the total antifoulant composition.

6. 6. The method of any one of claims 1 to 5, wherein the one or more antioxidants are selected from 1,4-phenylenediamine, its alkylated or phenyl derivatives, and combinations thereof.

7. 7. The method of any one of claims 1, 5, or 6, wherein the antioxidant comprises from about 1% to about 10% by weight of the antifouling composition.

8. The method of claim 1 or 5, wherein the antipolymerization agent comprises from about 1% to about 10% by weight of the antifoulant composition.

9. 9. The method of any one of claims 1, 5, or 8, wherein the anti-polymerization agent is selected from 2,2,6,6-tetramethylpiperidinyl-1-oxyl, 1-hydroxy-2,2,6,6-tetramethylpiperidine, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidinyl-1-oxyl, 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine, and 1-hydroxy-4-oxo-2,2,6,6-tetramethylpiperidine, or combinations thereof.

10. The composition of claims 1 or 5, wherein the dispersant comprises from 50% to about 90% by weight of the soilblocker composition.

11. 11. The method of claim 1, 5, or 10, wherein the dispersant is a blend of two or more fatty acid amides.

12. 12. The method of claim 11, wherein the blend has a ratio of the first fatty acid amide to the second fatty acid amide of from about 1:1 to about 1:10, or from about 1:1 to about 1:

2.

13. 13. The method of claim 11 or 12, wherein the fatty acids are tall oil and diamines.

14. 14. The method of any one of claims 11 to 13, wherein the first fatty acid amide is a reaction product of a fatty acid with trimethylamine (TEA) and the second fatty acid amide is a reaction product of a fatty acid with tetraethylenepentamine (TEPA).

15. 6. The method of claim 1 or 5, wherein the solvent is selected from glycols and aromatic naphthas, and combinations thereof.

Images