Method for Preventing Fouling of Heat Exchanger in Petroleum Process

Abstract

Provided is a novel method which enables the highly efficient prevention of the fouling of a heat exchanger in a petroleum process.　In one aspect, a method for preventing the fouling of a heat exchanger in a petroleum process using a fouling inhibitor is provided, the fouling preventing method comprising: adding a fouling inhibitor comprising a phosphite ester compound and a succinic acid imide compound to a process fluid when the H / C atom ratio in dirt in the heat exchanger is more than 1.3, and adding a fouling inhibitor comprising a phosphite ester compound and a succinate ester compound to the process fluid when the H / C atom ratio in the dirt in the heat exchanger is 1.3 or less; and feeding the process fluid containing the fouling inhibitor to the heat exchanger.

Description

Technical Field

[0001] The present disclosure relates to a method for preventing fouling of heat exchangers in oil processes.

Background Art

[0002] In the distillation process of an oil refining plant for refining crude oil, after the crude oil is heated in a heat exchanger and a heating furnace, it is sent to a distillation column for distillation operation. In the heat exchanger and the heating furnace, the crude oil undergoes a heat history and a large amount of fouling adheres. As one form of the fouling components, there is a form in which organic polymer components such as asphaltenes and sludge are mixed. The adhesion of fouling causes a decrease in the heat exchange rate of the heat exchanger and the heating furnace, resulting in an increase in the fuel consumption for maintaining the outlet temperature.

[0003] Patent Document 1 discloses an antifouling agent and an antifouling method for heat exchangers and heating furnaces to be added to a process fluid before a desalter. Patent Document 2 discloses a method for preventing fouling derived from asphaltenes in a preheater in an oil process using a phosphoric acid ester-based anticorrosive agent and a dispersant. Patent Document 3 discloses a method for preventing fouling derived from asphaltenes in a preheater in an oil process using a phosphite-based anticorrosive agent and a dispersant.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] Crude oil varies in composition and properties depending on the production area, oil field, etc. The classification of crude oil is based on the API gravity, which is the specific gravity unit of crude oil defined by the American Petroleum Institute, and the sulfur content in the crude oil. The API gravity is classified such that a higher numerical value indicates a lighter quality with a specific gravity of 10 being the same as that of water, and a lower numerical value indicates a heavier quality. Aromatic organic polymer components such as asphaltenes are considered to be one of the causes of fouling. Since these are heavy components, they tend to be contained in a large amount in heavy crude oil with a low API gravity value. Therefore, it has been considered to select a fouling inhibitor to be used according to the API gravity and asphaltene content of the crude oil.

[0006] However, the inventors have found a problem that the selection of the agent based on the API gravity and asphaltene content of the crude oil is insufficient. That is, even when the agent is selected based on the API gravity and asphaltene content, the expected fouling prevention effect may not be obtained.

[0007] In one aspect, the present disclosure provides a new method capable of efficiently preventing fouling of a heat exchanger in a petroleum process.

Means for Solving the Problems

[0008] In one aspect, the present disclosure is a method for preventing fouling of a heat exchanger in a petroleum process using a fouling inhibitor, wherein the fouling inhibitor contains a phosphite compound and a dispersant, and the dispersant is selected from the group consisting of a succinimide compound and a succinate compound, The fouling prevention method includes measuring the atomic ratio of hydrogen to carbon (H / C atomic ratio) in the carbon of the fouling of the heat exchanger, selecting a fouling inhibitor based on the H / C atomic ratio, adding the selected fouling inhibitor to a process fluid, and feeding the process fluid added with the fouling inhibitor to the heat exchanger, The selection of the fouling inhibitor is When the H / C atomic ratio of the fouling in the heat exchanger exceeds 1.3, a fouling inhibitor containing a succinimide compound is selected as the dispersant, When the H / C atomic ratio of the fouling in the heat exchanger is 1.3 or less, the present invention relates to a fouling prevention method including selecting a fouling inhibitor containing a succinic ester compound as the dispersant.

Advantages of the Invention

[0009] According to the method of the present disclosure, fouling of the heat exchanger in the petroleum process can be efficiently prevented.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0011] In the present disclosure, the content of asphaltene contained in crude oil and the specific gravity of crude oil are not necessarily directly related to the components of fouling that can occur in the heat exchanger in the petroleum process. Further, instead of the API degree and asphaltene content of crude oil, which have been conventionally considered as indicators for chemical selection, by using the H / C atomic ratio of the fouling in the heat exchanger, effective chemical selection becomes possible, and it is based on a new finding that fouling in the heat exchanger in the petroleum process can be efficiently prevented.

[0012] In the fouling prevention method according to the present disclosure, although the details of the mechanism by which effective chemical selection becomes possible and fouling in the heat exchanger in the petroleum process can be efficiently prevented are not clear, it is presumed as follows. That is, it was thought that when the asphaltene content in crude oil was high, a large amount of asphaltene-derived dirt would be generated or adhered, and when the asphaltene content in crude oil was low, the generation or adhesion of asphaltene-derived dirt would decrease. However, as a result of actually analyzing the dirt, it was found that the asphaltene content of crude oil does not necessarily match the components of the dirt generated in the heat exchanger in the petroleum process. The present disclosure focuses not on the properties of the crude oil flowing through the process, but on the dirt itself, specifically the H / C atomic ratio of the dirt. Since the H / C atomic ratio of the dirt is the ratio of hydrogen atoms and carbon atoms contained in the dirt, it can be said that it represents the properties (composition) of the dirt itself. For example, when the H / C atomic ratio exceeds 1.3, it can be estimated that the main component of the dirt is an organic polymer component other than asphaltene, and when the H / C atomic ratio is 1.3 or less (1.3 to 1.0), it is estimated that the main component is an organic polymer component mainly composed of asphaltene. The dispersant contained in the anti-fouling agent can prevent the deposition of dirt on the heat exchanger surface and the like by dispersing the generated dirt in the process fluid. Therefore, by selecting an effective dispersant according to the H / C atomic ratio of the dirt indicating the composition of the dirt and using it in combination with a phosphite compound, it becomes possible to select an effective chemical agent, and it is considered that the dirt in the heat exchanger in the petroleum process can be efficiently prevented. However, the present disclosure does not necessarily have to be limited to these concepts.

[0013] In the present disclosure, the "petroleum process" refers to all or part of the process from hydrocarbons such as crude oil as raw materials to the production of various petroleum products. The petroleum process may include, in one or more embodiments, heating hydrocarbons such as crude oil and separating the heated hydrocarbons into various components such as LPG, naphtha and other volatile oils and gas oil by utilizing the difference in boiling points in an atmospheric distillation unit. The petroleum process in the present disclosure may include, in one or more embodiments, a petroleum refining process.

[0014] In the present disclosure, "fouling" refers to one or more non-limiting embodiments that include asphaltene and other organic polymer components, or fouling that includes asphaltene and other components that adhere and / or accumulate in a heat exchanger.

[0015] In one or more non-limiting embodiments, the fouling prevention method of the present disclosure may include preventing these foulings from adhering to the heat exchanger by coating the iron-based metal surface of the heat exchanger by treating the heat exchanger with a chemical agent. "Fouling prevention" in the present disclosure includes preventing fouling generated in the heat exchanger from adhering to the heat exchanger.

[0016] In the present disclosure, a "heat exchanger" is a heat exchanger used in an oil process. Examples of heat exchangers include, in one or more non-limiting embodiments, a preheater (also referred to as a preheating heat exchanger or a preheat exchanger), a preheater, and a reboiler. In these heat exchangers, fouling is particularly likely to occur and accumulate in the high-temperature portion of about 200°C or higher. The fouling prevention method of the present disclosure is, in one or more embodiments, a fouling prevention method for a heat exchanger having a high-temperature portion that reaches about 200°C during treatment, for example, 180°C or higher, 190°C or higher, 200°C or higher, 210°C or higher, or 220°C or higher. The fouling prevention method of the present disclosure more effectively exhibits the fouling prevention effect in the portion that has reached about 200°C or higher in one or more embodiments. Examples of heat exchangers in an oil process include, in one or more embodiments, heat exchangers in an oil refining process, or preheaters in an oil process.

[0017] In the present disclosure, "process fluid" refers to a liquid or gas used in an oil process. Examples of process fluids include, in one or more embodiments, crude oil processed in an oil process or hydrocarbons derived therefrom. Examples of process fluids include, in one or more non-limiting embodiments, a liquid supplied to a preheater in an oil refining process, or a liquid in a preheater.

[0018] [Anti-fouling method] In one aspect, the present disclosure relates to a method for preventing fouling of a heat exchanger in a petroleum process using an anti-fouling agent containing a phosphite compound and a dispersant. The anti-fouling method of the present disclosure includes measuring the H / C atomic ratio of the fouling of the heat exchanger, selecting an anti-fouling agent based on the H / C atomic ratio, adding the selected anti-fouling agent to the process fluid, and feeding the process fluid added with the anti-fouling agent to the heat exchanger. The selection of the anti-fouling agent includes selecting an anti-fouling agent containing a succinimide compound as a dispersant when the H / C atomic ratio of the fouling of the heat exchanger exceeds 1.3, and selecting an anti-fouling agent containing a succinate compound as a dispersant when the H / C atomic ratio of the fouling of the heat exchanger is 1.3 or less.

[0019] In one form, the present disclosure is a method for preventing fouling of a heat exchanger in a petroleum process using an anti-fouling agent, which includes adding an anti-fouling agent containing a phosphite compound and a succinimide compound to the process fluid when the H / C atomic ratio of the fouling of the heat exchanger exceeds 1.3, and adding an anti-fouling agent containing a phosphite compound and a succinate compound to the process fluid when the H / C atomic ratio of the fouling of the heat exchanger is 1.3 or less, and feeding the process fluid added with the anti-fouling agent to the heat exchanger.

[0020] According to the anti-fouling method of the present disclosure, in one or more embodiments, since the anti-fouling agent is selected based on the H / C atomic ratio of the fouling of the heat exchanger, it is possible to select an anti-fouling agent (especially a dispersant) suitable for the generated or potentially generated fouling, and it is possible to achieve the effect of efficiently preventing fouling in the heat exchanger.

[0021] The anti-fouling method of the present disclosure, in one embodiment, includes measuring the H / C atomic ratio in the fouling of a heat exchanger. The measurement of the H / C atomic ratio includes, in one or more embodiments, collecting fouling from the heat exchanger and obtaining the H / C atomic ratio from the collected fouling. Obtaining the H / C atomic ratio from the collected fouling includes, in one or more embodiments, performing elemental analysis of the fouling to calculate the ratio of hydrogen atoms to carbon atoms. Examples of locations where fouling is collected include, in one or more embodiments, heat exchangers where a large amount of fouling adheres, and among them, the most fouled heat exchanger. Examples of heat exchangers where a large amount of fouling adheres include, in one or more embodiments, a heat exchanger located immediately before a heating furnace or on the heating furnace side (downstream from the desalination device towards the heating furnace) of the desalination device, and a heat exchanger with a high heating temperature (for example, a heat exchanger heated to 200 °C or higher). The elemental analysis of the fouling can be performed in accordance with JIS M 8819 Coal and Coke - Elemental Analysis Method by Instrumental Analysis. Specifically, it can be performed by the method of the examples.

[0022] The anti-fouling method of the present disclosure, in one embodiment, includes selecting an anti-fouling agent based on the obtained H / C atomic ratio. The selection of the anti-fouling agent includes selecting an anti-fouling agent containing a succinimide compound as a dispersant when the H / C atomic ratio of the fouling of the heat exchanger exceeds 1.3, and selecting an anti-fouling agent containing a succinate compound as a dispersant when the H / C atomic ratio of the fouling of the heat exchanger is 1.3 or less. By using the H / C atomic ratio as an index for the selection of the anti-fouling agent, particularly the dispersant, effective chemical selection may be made possible.

[0023] The anti-fouling method of the present disclosure, in one embodiment, includes adding the anti-fouling agent selected based on the H / C atomic ratio to the process fluid. That is, when the H / C atomic ratio of the fouling of the heat exchanger exceeds 1.3, an anti-fouling agent containing a phosphite compound and a succinimide compound is added to the process fluid, and when the H / C atomic ratio of the fouling of the heat exchanger is 1.3 or less, an anti-fouling agent containing a phosphite compound and a succinate compound is added to the process fluid.

[0024] [Phosphite compound] In one or more embodiments not particularly limited, the phosphite compound may include, for example, a phosphite compound represented by formula (I) to (IV), one having two structures of formula (II), or a dimer (dimerized product) of the compound of formula (II). [Chemical formula]

[0025] In formula (I), R 1 and R 2 are groups having 1 to 30 carbon atoms. R 1 and R 2 may be the same or different from each other, but are preferably the same.

[0026] In formula (II), R 3 , R 4 and R 5 are groups having 1 to 30 carbon atoms. R 3 , R 4 and R 5 may be the same or different from each other, but are preferably the same.

[0027] In formula (III), R 6 , R 7 , R 8 and R 9 are groups having 1 to 30 carbon atoms, R 10 and R 11 are divalent substituents having 1 to 30 carbon atoms, and X 1 is an oxygen atom, a carbon atom, or a divalent substituent having 1 to 5 carbon atoms. R 6 , R 7 , R 8 and R 9 may be the same or different from each other, but are preferably the same. R 10 and R 11 may be the same or different from each other.

[0028] In formula (IV), R 12 and R 13 are groups having 1 to 30 carbon atoms, R 14 , R 15 , R 16 and R 17 are divalent substituents having 1 to 30 carbon atoms, and X 2 is a carbon atom. R 12 and R 13 may be the same as or different from each other. R 14 , R 15 , R 16 and R 17 may be the same as or different from each other.

[0029] Examples of the group having 1 to 30 carbon atoms include, in one or more embodiments, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 1 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, an aralkyl group having 7 to 30 carbon atoms, or an alkylaryl group having 7 to 30 carbon atoms. The alkyl group, alkenyl group, aryl group, aralkyl group, and alkylaryl group may have a substituent in one or more embodiments. The alkyl group may be a straight-chain alkyl group or a branched-chain alkyl group in one or more embodiments. Examples of the divalent substituent having 1 to 30 carbon atoms include, in one or more embodiments, an alkylene group having 1 to 30 carbon atoms and the like. The alkylene group may have a substituent in one or more embodiments. The alkylene group may be a straight-chain alkylene group or a branched-chain alkylene group in one or more embodiments.

[0030] Examples of the phosphite compound represented by formula (I) include, in one or more embodiments, diethyl hydrogen phosphite, bis(2-ethylhexyl) hydrogen phosphite, bis(tridecyl) hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, diphenyl hydrogen phosphite, and the like.

[0031] As the phosphite compound represented by formula (II), in one or more embodiments, triphenyl phosphite, trisnonylphenyl phosphite, tricresyl phosphite, triethyl phosphite, tris(2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, tris(tridecyl) phosphite, trioleyl phosphite, tristearyl phosphite, diphenylmono(2-ethylhexyl) phosphite, diphenylmonodecyl phosphite, diphenylmono(tridecyl) phosphite, and tris(2,4-di-tert-butylphenyl) phosphite, etc. may be mentioned.

[0032] As the phosphite compound represented by formula (III), in one or more embodiments, tetraphenyldipropylene glycol diphosphite, and tetra(C 12 - 15 -alkyl)-4,4'-isopropylidenediphenyl diphosphite, etc. may be mentioned.

[0033] As the phosphite compound represented by formula (IV), in one or more embodiments, a mixture of bis(tridecyl)pentaerythritol diphosphite and bis(nonylphenyl)pentaerythritol diphosphite, bis(tridecyl)pentaerythritol diphosphite, bis(decyl)pentaerythritol diphosphite, and distearylpentaerythritol diphosphite, tetraphenyl(tetratridecyl)pentaerythritol tetraphosphite, and hydrogenated bisphenol A·pentaerythritol phosphite polymer, etc. may be mentioned.

[0034] As the phosphite compound, in one or more embodiments, from the viewpoint of further preventing fouling of heat exchangers in petroleum processes and / or further suppressing corrosion of storage tanks and chemical injection facilities, triphenyl phosphite, tris(nonylphenyl) phosphite, tricresyl phosphite, triethyl phosphite, tris(2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, tris(tridecyl) phosphite, trioleyl phosphite, tristearyl phosphite, diphenyl mono(2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, diphenyl mono(tridecyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, diethyl hydrogen phosphite, bis(2-ethylhexyl) hydrogen phosphite, bis(tridecyl) hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite or a combination thereof is preferred. From a similar viewpoint, as the phosphite compound, a phosphonic acid type phosphite compound is preferred, and diethyl hydrogen phosphite, bis(2-ethylhexyl) hydrogen phosphite, bis(tridecyl) hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite or a combination thereof is more preferred.

[0035] In the present disclosure, the phosphite compound may be an oil-soluble phosphite compound in one or more embodiments.

[0036] In one or more embodiments, the phosphite compound may be used alone or in combination of multiple types.

[0037] As the concentration of the phosphite compound added to the process fluid, in one or more embodiments, 0.1 to 40 ppm, 0.1 to 25 ppm, or 0.5 to 15 ppm can be mentioned. In the present disclosure, "ppm" means parts per million by mass (mass ppm) based on the process fluid, and refers to the amount (mg) of the thiophosphate compound per 1 kg of the process fluid.

[0038] [Dispersant] The anti-fouling agent used in the anti-fouling method of the present disclosure contains a dispersant. Examples of the dispersant include succinimide compounds and succinate compounds.

[0039] The succinimide compound is used when the H / C atomic ratio of the fouling that can occur in the heat exchanger exceeds 1.3. By adding a succinimide compound together with a phosphite compound to a process fluid in which fouling with an H / C atomic ratio exceeding 1.3 occurs or can occur, an excellent anti-fouling effect can be achieved. In one embodiment of the anti-fouling method of the present disclosure, the anti-fouling agent used when the H / C atomic ratio of the fouling exceeds 1.3 may contain other anti-fouling agents. In other embodiments, the dispersant substantially does not contain a succinate compound, or the dispersant consists essentially of only a succinimide compound.

[0040] The succinate compound is used when the H / C atomic ratio of the fouling that can occur in the heat exchanger is 1.3 or less. By adding a succinate compound together with a phosphite compound to a process fluid in which fouling with an H / C atomic ratio of 1.3 or less occurs or can occur, an excellent anti-fouling effect can be achieved. In one embodiment of the anti-fouling method of the present disclosure, the anti-fouling agent used when the H / C atomic ratio of the fouling is 1.3 or less may contain other anti-fouling agents. In other embodiments, the dispersant substantially does not contain a succinimide compound, or the dispersant consists essentially of only a succinate compound.

[0041] The succinimide compound has, in one or more embodiments, at least one of an alkenyl group and an alkyl group as a substituent. Examples of the succinimide compound having an alkenyl group include, in one or more embodiments, a succinimide compound in which at least one carbon atom of the succinimide group is substituted with a long-chain alkenyl group, a succinimide compound in which at least one carbon atom of the succinimide group is substituted with a long-chain alkenyl group and the nitrogen atom of the succinimide group is substituted with an alkyleneimine group or an aminoalkylene group, a succinimide compound in which the nitrogen atoms of two long-chain alkenyl group-substituted succinimides are bonded via a hydrocarbon chain or a nitrogen-containing hydrocarbon chain, and the like. Examples of the long-chain alkenyl group include, in one or more embodiments, an alkenyl group having 8 or more, 9 or more, 10 or more, 12 or more, 15 or more, or 16 or more carbon atoms. Examples of the hydrocarbon chain include a linear alkylene group having 2 or more, 4 or more, 10 or more, 12 or more, 15 or more, or 16 or more carbon atoms. Examples of the nitrogen-containing hydrocarbon chain include a divalent substituent having 1 or more or 2 or more nitrogen atoms and 2 or more, 4 or more, 10 or more, 12 or more, 15 or more, or 16 or more carbon atoms. Examples of the nitrogen-containing hydrocarbon chain include a diethylamino group and an ethylene polyethyleneimine group, and the like.

[0042] Examples of the succinimide compound having an alkyl group include, in one or more embodiments, a succinimide compound in which at least one carbon atom of the succinimide group is substituted with a long-chain alkyl group, a succinimide compound in which at least one carbon atom of the succinimide group is substituted with a long-chain alkyl group and the nitrogen atom of the succinimide group is substituted with an alkyleneimine group or an aminoalkylene group, a succinimide compound in which the nitrogen atoms of two long-chain alkyl group-substituted succinimides are bonded via a hydrocarbon chain or a nitrogen-containing hydrocarbon chain, and the like. Examples of the long-chain alkyl group include, in one or more embodiments, an alkyl group having 8 or more, 9 or more, 10 or more, 12 or more, 15 or more, or 16 or more carbon atoms.

[0043] Examples of the succinimide compound having at least one of an alkenyl group and an alkyl group include compounds represented by the following formulas (V) to (VIII) in one or more embodiments. [Chemical formula]

[0044] In formula (V), R 21 and R 22 represent an alkyl group having a number average molecular weight of 300 or more and 7000 or less, or an alkenyl group having a number average molecular weight of 300 or more and 7000 or less, and n represents an integer of 0 to 8. R 21 and R 22 may be the same as or different from each other.

[0045] In formula (VI), R 23 represents an alkyl group having a number average molecular weight of 300 or more and 7000 or less, or an alkenyl group having a number average molecular weight of 300 or more and 7000 or less, and m represents an integer of 0 to 8.

[0046] In formula (VII), R 24 , R 26 and R 27 represent an alkyl group having a number average molecular weight of 300 or more and 7000 or less, or an alkenyl group having a number average molecular weight of 300 or more and 7000 or less, and R 25 is an alkylene group having 1 to 5 carbon atoms. R 26 and R 27 may be the same as or different from each other.

[0047] In formula (VIII), R 28 represents an alkyl group having a number average molecular weight of 300 or more and 7000 or less, or an alkenyl group having a number average molecular weight of 300 or more and 7000 or less, and R 29 is an alkylene group having 1 to 5 carbon atoms.

[0048] The number average molecular weight of the alkyl group and the alkenyl group is, in one or more embodiments, 500 or more and 5000 or less, 500 or more and less than 5000, 500 or more and 4000 or less, 700 or more and 4000 or less, or 800 or more and 3500 or less.

[0049] In one or more embodiments, the alkyl group and the alkenyl group may be linear or branched. R 21 , R 22 , R 23 , R 24 and R 28 Examples include, in one or more embodiments, a polyethylene group, a polyisopropyl group, a polyisoprene group, a polybutene group, a polyisobutene group, a polybutenyl group, and a polyisobutenyl group, etc., and preferably a polybutenyl group and a polyisobutenyl group, etc.

[0050] R 25 and R 29 Examples include, in one or more embodiments, a methylene group, an ethylene group, a propyl group, and an isopropyl group, etc.

[0051] In one or more embodiments, n and m are 0, 1, 2, 3, or 4. In formula (V), "-CH 2 CH 2 -[NHCH 2 CH 2 n -" and in formula (VI), "-CH 2 CH 2 -[NHCH 2 CH 2 m -" include an ethylene group, a diethyleneamino group, and an ethylene polyethyleneimine group, etc.

[0052] In one or more embodiments, the weight average molecular weight of the succinimide compound is 3,000 to 15,000, or 5,000 to 12,000. The weight average molecular weight of the succinimide compound is determined by size exclusion chromatography and can be specifically measured by the method described in the examples. ​​

[0053] In one or more embodiments, the succinimide compound may be used alone or in combination of multiple types.

[0054] In one or more embodiments, the concentration of the succinimide compound added to the process fluid is 0.1 to 50 ppm, 0.1 to 30 ppm, or 1 to 25 ppm.

[0055] In one or more embodiments, the ratio (concentration of phosphite compound: concentration of succinimide compound) of the concentration (content) (ppm) of the phosphite compound added to the process fluid to the concentration (content) (ppm) of the succinimide compound is 5:1 to 1:5, 3:1 to 1:4, 2:1 to 1:3.5, or 1:1 to 1:3. In one or more embodiments, the anti-fouling method of the present disclosure includes adding a phosphite compound and a succinimide compound to the process fluid such that the ratio (concentration of phosphite compound: concentration of succinimide compound) of the concentration (content) (ppm) of the phosphite compound to the concentration (content) (ppm) of the succinimide compound in the process fluid is 5:1 to 1:5, 3:1 to 1:4, 2:1 to 1:3.5, or 1:1 to 1:3.

[0056] In one or more embodiments, the succinate compound has an alkenyl group as a substituent. In one or more embodiments, the succinate compound having an alkenyl group includes a long-chain alkenyl-substituted succinate compound and the like. In one or more embodiments, the long-chain alkenyl-substituted succinate compound can be prepared by subjecting succinic anhydride having a long-chain alkenyl group and an alcohol or an aromatic hydroxyl compound to a condensation reaction in the presence of an acidic catalyst.

[0057] As the long-chain alkenyl group, in one or more embodiments, an alkenyl group having 8 or more, 9 or more, 10 or more, 12 or more, 15 or more, 16 or more, or 20 or more carbon atoms can be mentioned. As the long-chain alkenyl group, in one or more embodiments, a polyethylene group, a polypropylene group, a polyisobutylene group, a polybutene group, etc. can be mentioned. As the alcohol, in one or more embodiments, an alcohol having 1 to 10 carbon atoms and having 1 to 6 hydroxyl groups, etc. can be mentioned. As the alcohol, in one or more embodiments, a monohydric alcohol, a polyhydric alcohol, etc. can be mentioned. As the alcohol, in one or more embodiments, methanol, ethanol, propanol, butanol, isobutanol, benzyl alcohol, octadecanol, eicosanol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, diethylene glycol monoethyl ether, propylene glycol, dipropylene glycol, tripropylene glycol, glycerol, erythritol, sorbitol, mannitol, glucose, galactose, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, 1,1,1-trimethylolbutane, pentaerythritol, dipentaerythritol, etc. can be mentioned. As the aromatic hydroxyl compound, in one or more embodiments, phenol, naphthol, etc. can be mentioned.

[0058] As the long-chain alkenyl-substituted succinic acid ester compound, in one or more embodiments, a polyisobutenyl succinic acid ester, etc. can be mentioned. As the carbon number of the polyisobutenyl group in the polyisobutenyl succinic acid ester, in one or more embodiments, it is 20 to 250, 50 to 100, or 60 to 90. As the average molecular weight of the polyisobutenyl succinic anhydride used for the preparation of the polyisobutenyl succinic acid ester, in one or more embodiments, it is 400 to 3000, 600 to 1500, or 800 to 1300. As the polyisobutenyl succinic acid ester, in one or more embodiments, polyisobutenyl pentaerythritol succinic acid ester and the like can be mentioned.

[0059] The succinic acid ester compound may be used alone or in combination of multiple types in one or more embodiments.

[0060] As the concentration of the succinic acid ester compound added to the process fluid, in one or more embodiments, 0.1 to 50 ppm, 0.1 to 30 ppm, or 1 to 25 ppm can be mentioned.

[0061] The ratio (concentration of phosphite compound: concentration of succinic acid ester compound) of the concentration (content) (ppm) of the phosphite compound added to the process fluid to the concentration (content) (ppm) of the succinic acid ester compound is, in one or more embodiments, 5:1 to 1:5, 3:1 to 1:4, 2:1 to 1:3.5, or 1:1 to 1:3. The anti-fouling method of the present disclosure includes adding a phosphite compound and a succinic acid ester compound to the process fluid such that the ratio (concentration of phosphite compound: concentration of succinic acid ester compound) of the concentration (content) (ppm) of the phosphite compound to the concentration (content) (ppm) of the succinic acid ester compound in the process fluid is 5:1 to 1:5, 3:1 to 1:4, 2:1 to 1:3.5, or 1:1 to 1:3 in one or more embodiments.

[0062] The location where the anti-fouling agent is added to the process fluid is not particularly limited. The addition location of the anti-fouling agent includes, in one or more embodiments, a location where the active ingredient of the above concentration can be introduced into the heat exchanger to be protected from fouling, or the location in front of the target heat exchanger. The anti-fouling agent may be added continuously or intermittently in one or more embodiments.

[0063] In one or more embodiments, the anti-fouling method of the present disclosure may include performing a basic treatment of supplying a process fluid containing the above anti-fouling agent at a high concentration to a heat exchanger (heat exchanger in the initial state) after regular cleaning (when operation resumes). This can efficiently suppress the adhesion of dirt to the heat exchanger after regular cleaning (when operation resumes) where dirt is relatively likely to adhere, and suppress the performance degradation of the heat exchanger due to the adhesion of dirt. Also, by performing the basic treatment using a high-concentration anti-fouling agent after regular cleaning (when operation resumes), it may be possible to reduce the amount of anti-fouling agent used in the treatment after transitioning to steady operation (steady treatment). The high concentration refers to a concentration higher than the concentration of the anti-fouling agent used in the steady treatment in one or more embodiments.

[0064] Figure 1 is a block diagram showing an example of a petroleum refining apparatus including an atmospheric distillation column. In this petroleum refining apparatus, the crude oil supplied via pump 9 is heated to 110 - 140°C in preheater 1 (heat exchanger 1) and desalted in desalter 2. Then, after being heated to 150 - 180°C in preheater 3 (heat exchanger 3), it is sent to preflash tower 4 where low-boiling gas components are separated. And it is heated to 240 - 280°C by preheater 5 (heat exchanger 5) and preheater 6 (heat exchanger 6), heated to 350 - 380°C in heating furnace 7, and introduced into atmospheric distillation column 8. The bottoms liquid from the bottom of atmospheric distillation column 8 is sent as a heat source to heat exchangers 5 and 6 via pump 10.

[0065] In one or more embodiments, the anti-fouling method of the present disclosure can be used to prevent fouling of preheater 3 (heat exchanger 3), preheater 5 (heat exchanger 5), and / or preheater 6 (heat exchanger 6) in the petroleum refining apparatus shown in Figure 1.

[0066] When the anti-fouling method of the present disclosure is performed in the heat exchangers 5 and 6 of the oil process of FIG. 1, as the location for adding the chemical agent, in one or more embodiments not limited thereto, the location indicated by arrow A in FIG. 1 in front of the heat exchangers 5 and 6 can be mentioned, but it may also be the location indicated by arrow C further in front. In the heat exchangers 5 and 6 of FIG. 1, when the anti-fouling method of the present disclosure is performed on the heating side, as the location for adding the chemical agent, in one or more embodiments not limited thereto, the location indicated by arrow B in FIG. 1 in front of the heat exchangers 5 and 6 can be mentioned. The location for adding the chemical agent in the present disclosure is not limited to the above locations. For example, it may be the location indicated by arrow D in FIG. 1 in front of the desalination device 2 (upstream side of the desalination device 2) (for example, in front of the heat exchanger 1 arranged in front of the desalination device 2 (upstream side of the heat exchanger 1)).

[0067] The present disclosure further relates to one or more of the following embodiments. [1] A method for preventing fouling of a heat exchanger in an oil process using an anti-fouling agent, wherein the anti-fouling agent contains a phosphite compound and a dispersant, and the dispersant is selected from the group consisting of a succinimide compound and a succinate compound. The anti-fouling method includes measuring the atomic weight ratio of hydrogen to carbon (H / C atomic ratio) in the fouling of the heat exchanger, selecting an anti-fouling agent based on the H / C atomic ratio, adding the selected anti-fouling agent to the process fluid, and feeding the process fluid added with the anti-fouling agent to the heat exchanger, The selection of the anti-fouling agent is when the H / C atomic ratio of the fouling of the heat exchanger exceeds 1.3, selecting an anti-fouling agent containing a succinimide compound as the dispersant, when the H / C atomic ratio of the fouling of the heat exchanger is 1.3 or less, selecting an anti-fouling agent containing a succinate compound as the dispersant, including an anti-fouling method. [2] A method for preventing fouling of a heat exchanger in an oil process using an anti-fouling agent, wherein When the H / C atomic ratio of the fouling in the heat exchanger exceeds 1.3, an anti-fouling agent containing a phosphite compound and a succinimide compound is added to the process fluid. When the H / C atomic ratio of the fouling in the heat exchanger is 1.3 or less, an anti-fouling agent containing a phosphite compound and a succinate compound is added to the process fluid, and An anti-fouling method including feeding the process fluid added with the anti-fouling agent to the heat exchanger. [3] Adding the anti-fouling agent to the process fluid such that the ratio of the concentration (content) (ppm) of the phosphite compound to the dispersant in the process fluid supplied to the heat exchanger is 5:1 to 1:5, the anti-fouling method according to [1] or [2]. [4] Adding the phosphite compound to the process fluid such that the concentration of the phosphite compound in the process fluid supplied to the heat exchanger is 0.1 to 40 ppm, the anti-fouling method according to any one of [1] to [3]. [5] Adding the dispersant to the process fluid such that the concentration of the dispersant in the process fluid supplied to the heat exchanger is 0.1 to 50 ppm, the anti-fouling method according to any one of [1] to [4].

[0068] Hereinafter, the present disclosure will be further described using examples. However, the present disclosure is not construed as being limited to the following examples.

Examples

[0069] [Agents] Phosphite: A phosphite compound represented by formula (I) (oil-soluble) Succinimide: A succinimide compound represented by formula (V), molecular weight 10,000 Succinate: A polyalkenyl-substituted succinate compound, molecular weight 10,000

[0070] The molecular weight of the above compounds is the weight average molecular weight and can be measured by size exclusion chromatography. The measurement conditions are as follows. Measurement Conditions Column: Styrene - divinylbenzene crosslinked gel Eluent: Tetrahydrofuran Flow rate: 0.7 ml / min Column temperature: 40 °C

[0071] [Measurement of API gravity of crude oil samples] Three types of crude oil samples (Crude oil 1 - 3) were prepared. The API gravity of the crude oil was determined according to JIS K2249 (Crude oil and petroleum products - Method for determining density -), and the properties were classified as shown in the following table according to the criteria determined based on the API gravity.

Table 1

[0072] [Fouling prevention test] The fouling prevention test is a test for examining the fouling prevention effect of chemicals for petroleum refining. As a test member for attaching fouling, the heating tube (heat rod) 21 shown in Fig. 2 is used. The heating tube is brought into contact with oil, and the fouling attachment situation is measured. This heating tube 21 is used in the thermal stability tester specified in JIS K2276, and is made of mild steel with enlarged diameters at the ends 21a, 21b and a reduced diameter at the middle part 21c, having a constricted tube shape. This heating tube 21 is inserted into the heating tube holder 22 having the tube shape shown in Fig. 3. Inflow pipes 23a and outflow pipes 23b are connected to the upper and lower parts of the heating tube holder 22, and a thermocouple 24 is inserted into the central part of the heating tube 21. It is possible to pass an electric current from both parts 21a, 21b of the heating tube 21 so that the temperature sensed by the thermocouple 24 becomes a predetermined temperature by a temperature regulator (not shown). The inflow pipe 23a is connected to a tank (not shown) containing the sample to be evaluated. The test apparatus used was a HotLiquidProcessSimurator tester manufactured by Alcor Co., Ltd. equipped with the above - mentioned heating tube 21.

[0073] The heating pipe 21 was heated under the following conditions by the test apparatus, and the sample in the tank was introduced from the inflow pipe 23a to conduct the test. Since it is partitioned inside the tank, the returned samples do not mix. [Heating Conditions] Temperature of the heating pipe 21: 350 - 360 °C (heating up over 20 minutes) Temperature of the tank, line, and pump: 100 °C Sample volume: 500 ml Sample introduction flow rate: 1 ml / min System pressure: 500 - 600 psi (pressure adjustment with nitrogen) Test time: 5 hours

[0074] [Determination of the H / C Atomic Ratio of Fouling in Crude Oil Samples] Fouling from the heat exchanger of the plant where the crude oil sample was obtained was collected, and elemental analysis was performed on the collected fouling in accordance with JIS M 8819 (Coal and Coke - Elemental Analysis Method by Instrumental Analysis Equipment) to quantify carbon atoms and hydrogen atoms. Using the obtained measurement values, the atomic weight ratio of hydrogen to carbon (H / C) in the fouling of the plant where each crude oil sample was obtained was obtained. Specifically, for the elemental analysis, the sample (fouling) was burned in an oxygen or oxygen-containing carrier gas stream, and the generated gas was changed into carbon dioxide, water vapor, and nitrogen using a catalyst and a reducing agent. Then, they were led to a gas analysis section to measure each component, and the obtained measurement values were used to calculate the mass percentage with respect to the anhydrous sample using the formula described in JIS M 8819 to quantify carbon and hydrogen. The results are shown in the following table.

Table 2

[0075] [Preparation of Test Samples] Test samples were prepared by adding the chemicals shown in Table 1 below to Crude Oil Samples 1 - 3 such that the concentrations of the phosphite compound and the dispersant were 10 ppm and 20 ppm, respectively.

[0076] [Fouling Prevention Test Using Test Samples with Added Chemicals] Using the prepared test samples, the above [fouling prevention test] was conducted. The fouling prevention effect was evaluated based on the change in the outlet temperature (Δt) of the samples according to the following evaluation criteria. The results are shown in the table below. For BLANK1-3, crude oil samples 1-3 (without addition of chemicals) were used. [Change in the outlet temperature of the sample: Δt] The temperature change (Δt) between the sample temperature at the highest temperature after the start of the test and the sample temperature after 5 hours was measured at the outlet pipe 23b (the outlet of the heating section). The larger the fouling adheres to the heating pipe 21, the larger Δt becomes. Evaluation criterion A: Δt is 5 or less B: Δt exceeds 5 and is less than 8 C: Δt is 8 or more and less than 15 D: Δt is 15 or more

[0077]

Table 3

[0078] As shown in the above table, when the H / C atomic ratio of the fouling exceeds 1.3, by using a fouling inhibitor containing a phosphite ester and a succinimide, compared with the case of using a fouling inhibitor containing a phosphite ester and a succinate ester, an excellent fouling adhesion suppression effect was obtained. Also, when the H / C atomic ratio of the fouling is 1.3 or less, by using a fouling inhibitor containing a phosphite ester and a succinate ester, compared with the case of using a fouling inhibitor containing a phosphite ester and a succinimide, an excellent fouling adhesion suppression effect was obtained. Since crude oil 3 is medium-quality, in the selection of a fouling inhibitor according to the properties of the crude oil, the effect of the succinate ester, which is effective for fouling mainly composed of asphaltene, was expected. However, a better fouling adhesion suppression effect was obtained by using succinimide in combination as a dispersant. It was confirmed that the H / C atomic ratio of the fouling in the actual machine (heat exchanger) treating this crude oil is 1.5, and it does not necessarily match the properties of the crude oil. Therefore, it was confirmed that by measuring the H / C atomic ratio in the fouling of the heat exchanger and appropriately using antifouling agents (particularly dispersants) according to the obtained H / C atomic ratio, fouling can be prevented more efficiently.

Claims

1. A method for preventing fouling of a heat exchanger in an oil process using an antifouling agent, wherein the antifouling agent contains a phosphite compound and a dispersant, and the dispersant is selected from the group consisting of a succinimide compound and a succinate compound, the antifouling method comprising: measuring the atomic ratio of hydrogen to carbon (H / C atomic ratio) in the fouling of the heat exchanger; selecting an antifouling agent based on the H / C atomic ratio; adding the selected antifouling agent to the process fluid; and feeding the process fluid added with the antifouling agent to the heat exchanger, wherein the selection of the antifouling agent is such that: when the H / C atomic ratio of the fouling of the heat exchanger exceeds 1.3, an antifouling agent containing a succinimide compound as the dispersant is selected; when the H / C atomic ratio of the fouling of the heat exchanger is 1.3 or less, an antifouling agent containing a succinate compound as the dispersant is selected.

2. The antifouling method according to claim 1, comprising adding the antifouling agent to the process fluid such that the ratio of the concentrations (ppm) of the phosphite compound and the dispersant in the process fluid supplied to the heat exchanger is 5:1 to 1:

5.

3. The antifouling method according to claim 1 or 2, comprising adding the phosphite compound to the process fluid such that the concentration of the phosphite compound in the process fluid supplied to the heat exchanger is 0.1 to 40 ppm.

4. The antifouling method according to any one of claims 1 to 3, comprising adding the dispersant to the process fluid such that the concentration of the dispersant in the process fluid supplied to the heat exchanger is 0.1 to 50 ppm.

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