Refinery fouling prevention process

Abstract

To provide an additive to reduce fouling of crude hydrocarbon refinery components.SOLUTION: Fouling in a hydrocarbon refining process is reduced by adding to a crude hydrocarbon for a refining process, an additive combination comprising: (A) a polyalkenyl-substituted carboxylic acid or anhydride; and (B) an overbased metal hydrocarbyl-substituted hydroxybenzoate detergent; where the mass:mass ratio of (A) to (B) is in the range of 10:1 to 1:10, and the treatment rate of the additive combination is in the range of 5 to 1000 ppm by mass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an additive and a method and system for using the additive to reduce fouling of crude hydrocarbon refinery components. [Background technology]

[0002] Petroleum refineries incur significant additional energy costs due to fouling and the resulting attendant inefficiencies caused by such fouling. More specifically, the thermal processing of crude oils, blends, and fractions in heat transfer equipment, such as heat exchangers, is hindered by the precipitation of insoluble asphaltenes and other contaminants (e.g., particulate matter and salts) that can be found in crude oil. Furthermore, the asphaltenes and other organics can be thermally decomposed into coke when exposed to high heater tube surface temperatures. Fouling in heat exchangers receiving petroleum-type process streams can occur as a result of a number of mechanisms, including chemical reaction, corrosion, deposition of insoluble impurities present in the stream, and deposition of materials rendered insoluble by the temperature difference (ΔT) between the process stream and the heat exchanger walls. For example, naturally occurring asphaltenes can precipitate from the crude oil process stream, thermally decompose to form coke, and adhere to the hot surfaces. The high ΔT found in heat transfer operations results in high surface and skin temperatures when the process stream is introduced to the heater tube surface, which contributes to insoluble particulate matter deposition. Another common cause of fouling is attributed to the presence of salts, particulate matter, and impurities (e.g., inorganic contaminants) found in the crude oil stream. For example, iron oxides / sulfides, calcium carbonate, silica, sodium chloride, and calcium chloride have all been found to directly bind to the surface of fouled heater rods and result in coke deposits. These solids promote and / or provide an opportunity for incidental fouling of the crude oil.

[0003] The buildup of insoluble deposits on heat transfer equipment causes undesirable insulating effects and reduces the efficiency of its heat transfer. Fouling also reduces the cross-sectional area of the process equipment, which reduces flow rates and desired pressure differentials, resulting in suboptimal operation. To overcome these disadvantages, heat transfer equipment is typically shut down and mechanically or chemically cleaned, resulting in lost production time. Therefore, there is a need to prevent fouling and reduce deposition / adhesion of particulate matter and asphaltenes by the heated surfaces before the asphaltenes are thermally cracked or coked. This would improve the performance of the heat transfer equipment, reduce or eliminate scheduled outages for fouling mitigation work, and reduce the energy costs associated with its processing activity. The art describes the addition of polyalkyl succinic acid derivative additives, i.e., succinimides, to reduce fouling. See, for example, US-A-5,368,777 and WO-A-2011 / 014215. However, there is a need to further improve anti-fouling performance. Similarly, WO-2014 / 123736-A2 describes an antifouling composition and method for inhibiting fouling on structural components of systems exposed to flowing hydrocarbon or petrochemical streams, wherein the antifouling composition can include at least one polyalkylene anhydride ester dispersant and an alkyl phosphate phenate. Summary of the Invention

[0004] The present invention provides improvements in anti-fouling performance. Accordingly, in a first aspect, the present invention provides a method for reducing fouling in a hydrocarbon refining process, the method comprising the steps of providing a crude hydrocarbon for the refining process; and adding to the hydrocarbon an additive combination, the additive combination comprising the following components: (A) a polyalkenyl-substituted carboxylic acid or anhydride, and (B) an overbased metal hydrocarbyl-substituted hydroxybenzoate detergent dispersed in a diluent; wherein the weight:weight ratio of (A) to (B) is in the range of 10:1 to 1:10, for example, 3:1 to 1:3, and the treat rate of the additive combination is in the range of 5 to 1,000 ppm by weight. In a second aspect, the present invention provides a system for refining hydrocarbons, the system comprising: (C) At least one crude hydrocarbon refining component; and (D) a crude hydrocarbon in fluid communication with said at least one refinery component, said crude hydrocarbon comprising a combination of additives as defined in the first aspect of the present invention. In a third aspect, the present invention provides the use of a combination of additives as defined in the first aspect of the invention in a crude hydrocarbon to reduce fouling during the use of the crude hydrocarbon in a hydrocarbon refinery process. DETAILED DESCRIPTION OF THE INVENTION

[0005] definition The following definitions are provided for purposes of explanation and non-limiting purposes. "Fouling" refers to the accumulation of unwanted materials on surfaces of process equipment and the like. "Particulate-induced fouling" generally refers to fouling caused primarily by the presence of varying amounts of organic or inorganic particulate matter. Organic particulate matter (e.g., precipitated asphaltenes and coke particles) includes, but is not limited to, insoluble matter that precipitates out of solution when there is a change in process conditions (e.g., temperature, pressure, or concentration) or a change in the composition of the feed stream (e.g., due to the occurrence of a chemical reaction). Inorganic particulate matter includes, but is not limited to, silica, iron oxide, iron sulfide, alkaline earth metal oxides, sodium chloride, calcium chloride, and other inorganic salts. One major source of these particulate matter results from incomplete solids removal during desalting and / or other particulate matter removal processes. Solids contribute to the fouling of crude oils and blends due to the physical effect of altering the surface area of heat transfer equipment, allowing for longer downtime at wall temperatures, and causing coke formation from asphaltenes and / or crude oil(s).

[0006] "Alkyl" refers to a monovalent hydrocarbon radical containing no double or triple bonds and arranged in a branched or linear chain. "Alkylene" refers to a divalent hydrocarbon group containing no double or triple bonds and arranged in a branched or linear chain. The term "alkenyl" refers to a monovalent hydrocarbon radical containing one or more double bonds and arranged in a branched or linear chain. "PIB" refers to polyisobutylene and includes both standard or "conventional" polyisobutylene and highly reactive polyisobutylene (HRPIB). Reference to a particular group of polymers (e.g., polypropylene, poly(ethylene-co-propylene), or PIB) includes polymers containing primarily that individual monomer, with negligible amounts of other substitutions and / or interruptions along the polymer chain. In other words, reference to a group that is a polypropylene group does not require that the group consist of 100% propylene monomer, without any linking groups, substitutions, impurities, or other substituents (e.g., alkylene or alkenylene substituents). Such impurities or other substituents may be present in relatively small amounts, provided that they do not affect the commercial performance of the additive compared to the same additive containing the individual polymer substituents at 100% purity. A "hydrocarbyl" group refers to any monovalent group derived from a hydrocarbon, including monovalent alkyl, aryl, and cycloalkyl groups.

[0007] "Crude hydrocarbon refining components" generally refer to equipment or means involved in a process for refining crude hydrocarbons, such as an oil refining process, that is susceptible or capable of fouling. Crude hydrocarbon refining components include, but are not limited to, heat transfer components such as heat exchangers, furnaces, crude preheaters, coker preheaters, or any other heaters, FCC slurry bottoms, debutizer heat exchangers / towers, other feed / effluent heat exchangers and furnace air preheaters in refinery facilities, flare compressor components in refinery facilities, and steam cracker / steam reformer tubes in petrochemical facilities. Crude hydrocarbon refinery components may also include other equipment where heat transfer may occur, such as fractionation or distillation columns, scrubbers, reactors, liquid-jacketed tanks, pipe stills, cokers, and visbreakers. It is understood that a "crude hydrocarbon refinery component," as used herein, includes tubing, piping, baffles, and other process transport mechanisms within, at least partially comprising, and / or in direct fluid communication with any one of the above-described crude hydrocarbon refinery components. A reduction (or "reducing") in particulate matter-induced fouling is generally achieved when the ability of particulate matter to adhere to heated equipment surfaces is reduced, thereby reducing their impact on promoting fouling of crude oil(s), blends, and other refinery process streams.

[0008] In this specification, the following terms and expressions, if and when used, have the meanings given below: "active ingredients" or "ai" refers to added substances that are not diluents or solvents; "Comprising" or any cognate term specifies the presence of a stated feature, step, or integer or component, but does not preclude the presence or addition of one or more other features, steps, integers, components, or groups thereof; "consists of" or "consists essentially of" or cognate terms can be included within "comprises" or cognate terms, where "consisting essentially of" allows for the inclusion of substances that do not substantially affect the characteristics of the composition to which they are applied; "major amount" means 50% or more, preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more by weight of the composition; "minor amount" means less than 50%, preferably less than 40%, more preferably less than 30%, and even more preferably less than 20% by weight of the composition; "TBN" means total base number as measured by ASTM D2896. Additionally, as used herein, the following applies: "Calcium Content" means as measured by ASTM 4951; "Phosphorus Content" is as measured by ASTM D5185; "Sulfated ash content" means as measured by ASTM D874; "Sulfur Content" is as measured by ASTM D2622; "KV100" means kinematic viscosity at 100°C as measured by ASTM D445.

[0009] It will also be understood that the various ingredients used, both necessary and optional and customary, may react under conditions of formulation, storage or use, and that the present invention likewise provides the products obtainable or obtainable as a result of any such reactions. Further, it is understood that any upper and lower quantity, range, and ratio limits set forth herein may be independently combined. Polyalkenyl-substituted carboxylic acid or anhydride (A) (A) can constitute at least 1 to 7% by weight of the crude hydrocarbons, preferably 2 to 6% by weight. Preferably, it constitutes 3 to 5% by weight, even more preferably 4 to 5% by weight. It may be a mono- or polycarboxylic acid, preferably a dicarboxylic acid. The polyalkenyl group preferably has 8 to 400, for example 8 to 100, carbon atoms. The general formula of an exemplary anhydride in (A) can be depicted as follows: [ka]

[0010] where R 1 is C8~C 100 represents a branched or linear polyalkenyl group of the formula: The polyalkenyl moiety can have a number average molecular weight of 200-3,000, preferably 350-950. Suitable hydrocarbons or polymers used in the formation of the anhydrides used in the present invention to produce the polyalkenyl moieties include homopolymers, copolymers, or low molecular weight hydrocarbons. One class of such polymers is ethylene and / or olefins of the formula: H2C=CHR 1 At least one C3~C 28 and a polymer of an α-olefin, wherein R 1is a straight or branched chain alkyl group containing 1 to 26 carbon atoms, and the polymer contains carbon-carbon unsaturation, preferably a high degree of terminal ethenylidene unsaturation. Preferably, such polymers contain ethylene and a carboxylic acid having the formula above, where R 1 and copolymers with at least one α-olefin, wherein the alkyl group has 1 to 18, more preferably 1 to 8, and even more preferably 1 to 2 carbon atoms. Thus, useful α-olefin monomers and comonomers include, for example, propylene, butene-1, hexene-1, octene-1, 4-methylpentene-1, decene-1, dodecene-1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1, octadecene-1, nonadecene-1, and mixtures thereof (e.g., mixtures of propylene and butene-1). Exemplary of such polymers are propylene homopolymers, butene-1 homopolymers, ethylene-propylene copolymers, ethylene-butene-1 copolymers, and propylene-butene copolymers, where the polymers contain at least some terminal and / or internal unsaturation. Preferred polymers are unsaturated copolymers of ethylene and propylene, and ethylene and butene-1, which contain a small amount, e.g., 0.5 to 5 mole %, of C4 to C6 18 The polymers may contain non-conjugated diolefin comonomers. However, it is preferred that the polymers comprise only α-olefin homopolymers, copolymers of α-olefin comonomers, and copolymers of ethylene with α-olefin comonomers. The molar ethylene content of the polymers used is preferably in the range of 0 to 80%, more preferably 0 to 60%. When propylene and / or butene-1 are used as comonomer(s) with ethylene, the ethylene content of such polymers is most preferably between 15 and 50%, although higher or lower ethylene contents may also be present.

[0011] These polymers are made from α-olefin monomers, or a mixture of α-olefin monomers, or ethylene and at least one C3-C6 28The polymer may be prepared by polymerizing a mixture comprising an α-olefin monomer and an α-olefin monomer in the presence of a catalyst system comprising at least one metallocene (e.g., a cyclopentadienyl-transition metal compound) and an alumoxane compound. This process can be used to provide a polymer in which 95% or more of the polymer chains have terminal ethenylidene unsaturation. The percentage of polymer chains exhibiting terminal ethenylidene unsaturation can be determined by FTIR spectroscopy, titration, or 13 This latter type of copolymer can be determined by C NMR. 1 )=CH2, where R 1 is C1~C 26 , preferably C1 to C 18 , more preferably a C1-C8 and most preferably a C1-C2 alkyl group (e.g., methyl or ethyl), and POLY represents the polymer chain. 1 The chain length of the alkyl group will vary depending on the comonomer(s) selected for use in the polymerization. A small portion of the polymer chain may contain terminal ethenyl or vinyl unsaturation, i.e., POLY-CH=CH2, and a portion of the polymer may contain internal monounsaturation, e.g., POLY-CH=CH(R 1 ), where R 1 is as defined above. These terminally unsaturated copolymers can be prepared by known metallocene chemistry, as well as as described in U.S. Patent Nos. 5,498,809; 5,663,130; 5,705,577; 5,814,715; 6,022,929; and 6,030,930.

[0012] Another useful group of polymers are those produced by the cationic polymerization of isobutene and styrene. Typical polymers from this class include polyisobutenes obtained by polymerization of C4 refinery streams having a butene content of 35 to 75% by mass and an isobutene content of 30 to 60% by mass in the presence of a Lewis acid catalyst, such as aluminum trichloride or boron trifluoride. A preferred source of monomers for producing poly-n-butenes is a petroleum feedstream, such as Raffinate II. These feedstreams are disclosed in the art, for example, in U.S. Pat. No. 4,952,739. Polyisobutylene is the most preferred backbone because it is readily available from butene streams by cationic polymerization (e.g., using AlCl3 or BF3 catalysts). Such polyisobutylenes generally contain residual unsaturation along the chain, in an amount of one ethylenic double bond per polymer chain. In a preferred embodiment, polyisobutylene produced from a pure isobutylene stream or a Raffinate I stream is used to produce reactive isobutylene polymers having terminal vinylidene olefins. Preferably, these polymers, referred to as highly reactive polyisobutylenes (HR-PIB), have a terminal vinylidene content of at least 65%, e.g., 70%, more preferably at least 80%, and most preferably at least 85%. The preparation of such polymers is described, for example, in U.S. Pat. No. 4,152,499. HR-PIB is known and is commercially available from Glissopal. TM ) (from BASF) and Ultravis TM ) (from BP-Amoco).

[0013] Polyisobutylene polymers that can be used are generally based on hydrocarbon chains of 400 to 3,000. Methods for producing polyisobutylene are known. Polyisobutylene can be functionalized by halogenation (e.g., chlorination), by thermal "ene" reactions, or by radical grafting processes using catalysts (e.g., peroxides), as described below. The hydrocarbon or polymer backbone can be functionalized with carboxylic acid anhydride-generating moieties selectively at carbon-carbon unsaturated sites on the polymer or hydrocarbon chain, or randomly along the chain using any of the three methods described above or a combination of these in any order. Processes for reacting polymeric hydrocarbons with unsaturated carboxylic acids, anhydrides and the preparation of derivatives from such compounds are described in U.S. Patent Nos. 3,087,936; 3,172,892; 3,215,707; 3,231,587; 3,272,746; 3,275,554; 3,381,022; 3,442,808; 3,565,804; 3,912,764; 4,110,349; 4,234,435; 5,777,025; 5,891,953; and EP 0 382 450 B1; CA-1,335,895 and GB-A-1,440,219. The polymer or hydrocarbon can be functionalized with a carboxylic acid anhydride moiety by reacting the polymer or hydrocarbon under conditions that result in the addition of a functional moiety or functionalizing agent, i.e., an anhydride, to the polymer or hydrocarbon chain primarily at sites of carbon-carbon unsaturation (also referred to as ethylenic or olefinic unsaturation), utilizing a halogen-assisted functionalization (e.g., chlorination) process or the thermal "ene" reaction described above.

[0014] Selective functionalization can be achieved by halogenating, e.g., chlorinating or brominating, the unsaturated α-olefin polymer by passing chlorine or bromine through the polymer for 0.5 to 10 hours, preferably 1 to 7 hours, at 60 to 250° C., preferably 110 to 160° C., e.g., 120 to 140° C., until 1 to 8% by weight chlorine or bromine is obtained, based on the weight of the polymer or hydrocarbon. The halogenated polymer or hydrocarbon (hereafter referred to as the backbone) is then reacted with sufficient monounsaturated reactant, e.g., a monounsaturated carboxylic reactant, to add the required number of functional moieties to the backbone at 100 to 250° C., usually 180 to 235° C., for 0.5 to 10 hours, e.g., 3 to 8 hours, such that the resulting product will contain the desired number of moles of monounsaturated carboxylic reactant per mole of halogenated backbone. Alternatively, the backbone and the monocarboxylic reactant are mixed and heated while chlorine is added to the hot materials. Although chlorination usually serves to increase the reactivity of the starting olefin polymer with the monounsaturated functionalized reactant, it is not required for some of the polymers or hydrocarbons contemplated for use in this invention, particularly those preferred polymers or hydrocarbons having high end-linkage content and reactivity. Therefore, the backbone and the monounsaturated functional reactant (carboxylic reactant) are preferably contacted at elevated temperatures to cause an initial thermal "ene" reaction. Ene reactions are known.

[0015] The hydrocarbon or polymer backbone can be functionalized by randomly attaching functional moieties along the polymer chain by a variety of methods. For example, the polymer, in solution or in the solid state, can be grafted with the monounsaturated carboxylic reactant in the presence of a radical initiator, as described above. When performed in solution, the grafting occurs at elevated temperatures ranging from 100 to 260°C, preferably from 120 to 240°C. Preferably, radical-initiated grafting will be accomplished in an inorganic lubricating oil solution, e.g., a lubricating oil solution containing 1 to 50 wt. %, preferably 5 to 30 wt. %, of polymer, based on the initial total lubricating oil solution. Usable radical initiators include peroxides, hydroperoxides, and azo compounds, preferably those with boiling points above 100°C that thermally decompose to give radicals within the grafting temperature range. Representative examples of these radical initiators include azobutyronitrile, 2,5-dimethylhex-3-ene-2,5-bis-tert-butylperoxide, and dicumene peroxide. When used, the initiator is typically present in an amount between 0.005 and 1% by weight, based on the weight of the reaction mixture solution. Typically, the monounsaturated carboxylic acid reactant and the radical initiator are used in a weight ratio ranging from 1.0:1 to 30:1, preferably from 3:1 to 6:1. The grafting process is preferably carried out in an inert atmosphere, e.g., under a nitrogen blanket. The resulting grafted polymer is characterized by having carboxylic acid (or derivative) moieties randomly bonded along the polymer chain, with some of the polymer chain remaining ungrafted. The radical grafting process described above can also be utilized with other polymers and hydrocarbons used in the present invention.

[0016] The preferred monounsaturated reactants used to functionalize the backbone include mono- and di-carboxylic acid materials, i.e., acids or acid derivative materials, including (i) monounsaturated C4-C 10Dicarboxylic acids, (a) whose carboxyl groups are vicinyl (i.e., located on adjacent carbon atoms), and (b) at least one, preferably both, of the adjacent carbon atoms are part of the monounsaturation; (ii) derivatives of (i), such as anhydrides or mono- or di-esters of (i) derived from C1-C5 alcohols; (iii) monounsaturated C3-C5 alcohols. 10 Monocarboxylic acids in which the carbon-carbon double bond is conjugated with the carboxy group, i.e., having the structure -C=C-CO-; and (iv) derivatives of (iii), such as mono- or diesters of (iii) derived from C1-C5 alcohols. Mixtures of monounsaturated carboxylic reactants (i)-(iv) can also be used. Upon reaction with the backbone, the monounsaturation of the monounsaturated carboxylic reactant becomes saturated. Thus, for example, maleic anhydride becomes backbone-substituted succinic anhydride, and acrylic acid becomes backbone-substituted propionic acid. Typical examples of such monounsaturated carboxylic reactants are fumaric acid, itaconic acid, maleic acid, maleic anhydride, chloromaleic acid, chloromaleic anhydride, acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, and lower alkyl (e.g., C1-C4 alkyl) acid esters of the foregoing, such as methyl maleate, ethyl fumarate, and methyl fumarate. To provide the required functionality, the monounsaturated carboxylic reactant, preferably maleic anhydride, will typically be used in an amount ranging from an equimolar amount to a 100% weight excess, preferably a 5-50% weight excess, based on the moles of polymer or hydrocarbon. Unreacted excess monounsaturated carboxylic reactant can be removed from the final dispersant product, if desired, for example, by stripping, usually under reduced pressure.

[0017] Overbased Metal Detergents (B) Metal detergents are additives based on so-called metal "soaps," i.e., metal salts of acidic organic compounds, often referred to as surfactants. They generally contain a polar head with a long hydrophobic tail. Overbased metal detergents, which contain neutralized metal detergents as an outer layer consisting of metal base (e.g., carbonate) micelles, can be provided by incorporating a large amount of metal base by reacting an excess of metal base, e.g., oxide or hydroxide, with an acid gas such as carbon dioxide. Examples of detergents include metal salicylates, phenates, and salicylates, and combinations thereof. In the present invention, the overbased metal detergent (B) is preferably an overbased metal hydrocarbyl-substituted hydroxybenzoate, more preferably a hydrocarbyl-substituted salicylate detergent. The metal may be an alkali metal (e.g., Li, Na, K) or an alkaline earth metal (e.g., Mg, Ca). "Hydrocarbyl" means a group or radical containing carbon and hydrogen atoms and bonded to the remainder of the molecule through a carbon atom. It may contain heteroatoms, i.e., atoms other than carbon and hydrogen, provided that these do not alter the essentially hydrocarbon character and characteristics of the group. Examples of hydrocarbyls include alkyl and alkenyl. A preferred overbased metal hydrocarbyl-substituted hydroxybenzoate is calcium alkyl-substituted salicylate, and has the structure shown below: [ka]

[0018] where R is a straight chain alkyl group. There may be more than one R group attached to the benzene ring. - The R group may be in the o-, m- or p-position relative to the hydroxyl group, with the o-position being preferred. The R group may be in the o-, m- or p-position relative to the hydroxyl group. Salicylic acid is typically produced by the carboxylation of phenoxides by the Kolbe-Schmitt method, and in that case will generally be obtained in a mixture with uncarboxylated phenol (usually in a diluent). The salicylic acid may be unsulfurized or sulfurized, and may be chemically modified and / or contain additional substituents. Processes for sulfurizing alkyl salicylates are well known to those skilled in the art and are described, for example, in US 2007 / 0027057. The alkyl groups advantageously contain from 5 to 100, preferably from 9 to 30, and especially from 14 to 24 carbon atoms. The term "overbased" is used broadly to describe metal detergents in which the ratio of the number of equivalents of the metal moiety to the number of equivalents of the acid moiety is greater than 1. The term "low-based" is used to describe metal detergents in which the ratio of equivalents of metal moiety to acid moiety is greater than 1 and up to about 2.

[0019] By "overbased calcium salt of surfactant" is meant an overbased detergent in which the metal cation of the oil-insoluble metal salt is essentially calcium cation. Small amounts of other cations may be present in the oil-insoluble metal salt, but typically at least 80 mole %, more typically at least 90 mole %, e.g., at least 95 mole %, of the cations in the oil-insoluble metal salt are calcium ions. Cations other than calcium may result, for example, from the use of a surfactant salt in the preparation of the overbased detergent, in which the cation is a metal other than calcium. Preferably, the metal salt of the surfactant is calcium as well. Carbonated, overbased metal detergents typically contain amorphous nanoparticles. In addition, the art discloses nanoparticulate materials containing carbonates in the crystalline calcite and vaterite forms. The basicity of the detergent can be expressed as a total base number (TBN), often called base number (BN). The total base number is the amount of acid required to neutralize all of the basicity of the overbased material. The TBN can be measured using ASTM standard D2896 or an equivalent procedure. The detergent can have a low TBN (i.e., a TBN less than 50), a medium TBN (i.e., a TBN of 50 to 150), or a high TBN (i.e., a TBN greater than 150, e.g., 150 to 500). The basicity can also be expressed as a basicity index (BI), which is the molar ratio of total base to total soap in the overbased detergent.

[0020] Composition for reducing fouling The additives of the present invention can be used in anti-fouling compositions that can further include dispersants and / or hydrophobic oil solubilizers for the additive(s). Such solubilizers can include, for example, surfactants and / or carboxylic acid solubilizers. Additionally, the composition may also contain additives such as viscosity index improvers, antifoam agents, antiwear agents, demulsifiers, antioxidants and other corrosion inhibitors. [Example]

[0021] The present invention will now be illustrated by the following examples, which should not be construed as limiting the invention in any way. component: The following additive ingredients and oils were used: Component (A) : A composition comprising 80% polyisobutene succinic anhydride ("PIBSA") derived from polyisobutene having a number average molecular weight of 950 and 20% diluent in the form of SN150, Group I oil. Ingredient (B) : An overbased calcium salicylate detergent with a basicity index of 8. crude fuel oil : A blend of Basra Heavy (DIES1604959), Enbridge (DIES1603291), and Cimarex (DIES1506105) in proportions of 40%, 10%, and 50%, respectively.

[0022] test Tests were conducted using 150 mL samples of the above fuel oil blends without additive (as a control) and with either 1,000 or 500 ppm by weight of the additive component(s) as shown in the results table below added to the blend as a cutback. As a comparison to the prior art, one test was conducted with a succinimide additive (shown as PIBSAPAM in the results table below) comprising the reaction product of PIBSA (1,000 MW) and tetraethylenepentamine (42% ai and 44 base number in KOH / g). The test utilized a 5-rod JFTOT rig test designed to simulate refinery fouling prevention performance. The 5-rod JFTOT is an instrument with five independently heated test sections arranged in series. Each test section contains an electrically resistively heated steel rod encased in an electrically insulated outer steel jacket. The test fuel sample flows through the cavity between the rod and the jacket. The temperature of the rod is controlled at the center point of the rod and maintained constant throughout the test.

[0023] As the fuel flows over the hot rod, it absorbs heat from the rod and the temperature of the fuel leaving the test section is recorded. When deposits accumulate on the rods, they reduce the efficiency of heat transfer from the rods to the fuel, thus causing a decrease in the temperature of the fuel leaving the test section. The temperature difference at the fuel outlet between the start and end of the test is calculated for all five rods and summed, with higher numbers representing larger temperature differences and therefore more severe fouling. Tests were conducted for 6 hours at rod temperatures of 125°C, 195°C, 235°C, 275°C and 315°C, and for 5 hours at rod temperatures of 120°C, 160°C, 200°C, 240°C and 280°C.

[0024] result [Table 1]

[0025] The above results show that in both tests, the additive combination of the present invention ((A) + (B)) (at 1,000 ppm and in a 1:1 ratio) provided the best antifouling results, and that (A) and (B) act synergistically. They also show that the additive combination of the present invention provided even better results than PIBSAPAM. Comparison Test To demonstrate the surprising technical advantages of the additive combinations of the present invention over the additive combinations representative of WO-2014 / 123736-A2 ("'736"), the 5-hour tests described above were conducted using the following additive combinations: The present invention (A) PIBSA as described above; (B) Overbased calcium salicylate with a TBN of 217-233, a metal content of 7.9-8.1 wt. % and an ai of 70%. Comparative Example (A) PIBSA-pentaerythritol (molecular weight: 2,000-3,000) corresponding to the preferred embodiment described in paragraph

[0029] of '736; (B) Overbased calcium phenate with a TBN of 250-265, a metal content of 9.2-9.8 wt. %, and an ai of 57%. In both cases, the additive combination was used at a (A):(B) ratio of 3:1 and a treat rate of 500 ppm.

[0026] The results were as follows: control (0 ppm additive) -62 The present invention -8 Comparative Example -20 These results show that the present invention unexpectedly produced better anti-fouling results than the comparative example. Next, another preferred embodiment of the present invention will be described. 1. A method for reducing fouling in a hydrocarbon refining process, comprising the steps of providing a crude hydrocarbon for the refining process; and adding to the hydrocarbon a combination of additives, the combination of additives comprising the following components: (A) a polyalkenyl-substituted carboxylic acid or anhydride, and (B) an overbased metal hydrocarbyl-substituted hydroxybenzoate detergent dispersed in a diluent; wherein the weight:weight ratio of (A) to (B) is in the range of 10:1 to 1:10, preferably 3:1 to 1:3, and the treat rate of the additive combination is in the range of 5 to 1,000 ppm by weight. 2. The method according to 1 above, wherein in (A), the polyalkenyl substituent contains 8 to 400, preferably 12 to 100, more preferably 16 to 64 carbon atoms. 3. The method according to 1 or 2 above, wherein in (A), the polyalkenyl substituent has a number average molecular weight of 350 to 1,000, preferably 500 to 1,000. 4. The method according to any one of 1 to 3 above, wherein (A) is succinic anhydride. 5. The method according to claim 4, wherein (A) is polyisobutene succinic anhydride. 6. The method according to any one of 1 to 5 above, wherein in (B), the metal is calcium. 7. The method according to any one of 1 to 6 above, wherein in (B), the hydrocarbyl-substituted hydroxybenzoate is a salicylate. 8. The method according to any one of 1 to 7 above, wherein in (B), the hydrocarbyl group has 8 to 400, preferably 12 to 100, more preferably 16 to 64 carbon atoms. 9. The method according to any one of 1 to 8 above, wherein in (B), the cleaning agent has a TBN in the range of 150 to 500. 10. The method according to any one of 1 to 9 above, wherein the fouling is particulate matter-induced fouling. 11. (C) At least one crude hydrocarbon refining component; and (D) a crude hydrocarbon in fluid communication with said at least one refinery component, said crude hydrocarbon containing a combination of additives as defined in any of 1-9 above; 1. A system for refining hydrocarbons comprising: 12. The system of claim 11, wherein the refining component is selected from a heat exchanger, a furnace, a crude preheater, a coker preheater, an FCC slurry bottom, a developer heat exchanger, a developer tower, a feed / effluent heat exchanger, a furnace air preheater, a flare compressor, a steam cracker, a steam reformer, a distillation column, a fractionator, a scrubber, a reactor, a liquid-jacketed tank, a pipe sill, a coker, and a visbreaker. 13. Use of a combination of additives as defined in any of 1 to 9 above in a crude hydrocarbon to reduce fouling throughout the use of the crude hydrocarbon in a hydrocarbon refinery process.

Claims

1. 1. A method for reducing fouling in a hydrocarbon refining process, comprising the steps of providing a crude hydrocarbon for the refining process; and adding an additive combination to the hydrocarbon, the additive combination comprising the following components: (A) a polyalkenyl-substituted carboxylic acid or anhydride, and (B) an overbased metal hydrocarbyl-substituted hydroxybenzoate detergent dispersed in a diluent; wherein the weight:weight ratio of (A) to (B) is in the range of 10:1 to 1:10, preferably 3:1 to 1:3, and the combination of additives is added in the range of 5 to 1,000 ppm by weight.

2. 2. The method of claim 1, wherein in (A), the polyalkenyl substituent contains 8 to 400, preferably 12 to 100, more preferably 16 to 64 carbon atoms.

3. 3. The method of claim 1 or 2, wherein in (A), the polyalkenyl substituent has a number average molecular weight of 350 to 1,000, preferably 500 to 1,000.

4. 4. The method of claim 1, wherein (A) is succinic anhydride.

5. 5. The method of claim 4, wherein (A) is polyisobutene succinic anhydride.

6. 6. The method according to claim 1, wherein in (B), the metal is calcium.

7. The method according to any one of claims 1 to 6, wherein in (B), the hydrocarbyl-substituted hydroxybenzoate is a salicylate.

8. 8. The method of any one of claims 1 to 7, wherein in (B), the hydrocarbyl group has from 8 to 400, preferably from 12 to 100, more preferably from 16 to 64 carbon atoms.

9. 9. The method according to claim 1, wherein in (B), the cleaning agent has a TBN in the range of 150 to 500.

10. 10. The method of claim 1, wherein the fouling is particulate matter-induced fouling.

11. (C) At least one crude hydrocarbon refining component; and (D) a crude hydrocarbon in fluid communication with said at least one refinery component, said crude hydrocarbon containing a combination of additives as defined in any one of claims 1 to 9.

1. A system for refining hydrocarbons comprising:

12. 12. The system of claim 11, wherein the refining component is selected from a heat exchanger, a furnace, a crude preheater, a coker preheater, an FCC slurry bottoms, a development heat exchanger, a development tower, a feed / effluent heat exchanger, a furnace air preheater, a flare compressor, a steam cracker, a steam reformer, a distillation column, a fractionator, a scrubber, a reactor, a liquid-jacketed tank, a pipe sill, a coker, and a visbreaker.

13. 10. Use of a combination of additives as defined in any one of claims 1 to 9 in a crude hydrocarbon to reduce fouling throughout the use of said crude hydrocarbon in a hydrocarbon refinery process.

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