Method for preventing fouling of heat exchanger in petroleum process

Abstract

To provide a novel method capable of preventing fouling of a heat exchanger in a petroleum process.SOLUTION: A fouling prevention method of a heat exchanger in a petroleum process includes addition of a thiophosphate compound and a dispersant to a process fluid passing through the heat exchanger in the petroleum process.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] In the distillation process of a petroleum 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 as a result, a large amount of fouling adheres. The adhesion of fouling causes a decrease in the heat exchange rate of the heat exchanger and the heating furnace, and is one of the reasons for increasing the fuel consumption for maintaining the outlet temperature. As one form of fouling components, there is a form in which organic polymer components such as asphaltenes and sludge are mixed.

[0003] Patent Document 1 discloses an antifouling agent and an antifouling method for heat exchangers and heating furnaces added to a process fluid before a desalter. Patent Document 2 discloses a method for preventing fouling derived from asphaltenes in a preheater in a petroleum 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 a petroleum 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] In one aspect, the present disclosure provides a new fouling prevention method capable of preventing fouling of heat exchangers in petroleum processes.

Means for Solving the Problems

[0006] In one aspect, the present disclosure relates to a fouling prevention method for a heat exchanger in a petroleum process, which includes adding a thiophosphate ester compound and a dispersant to a process fluid passing through the heat exchanger.

[0007] In other aspects, the present disclosure relates to a fouling preventive agent for use in a fouling prevention method, which contains a thiophosphate ester compound and a dispersant.

Advantages of the Invention

[0008] According to the method of the present disclosure, a new fouling prevention method capable of preventing fouling of heat exchangers in petroleum processes can be provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] The "petroleum process" in the present disclosure refers to all or part of the processes from hydrocarbons such as crude oil as raw materials until various petroleum products are manufactured. The petroleum process may include, in one or more embodiments, heating hydrocarbons such as crude oil (raw materials), and separating the heated hydrocarbons into main components such as volatile oils like LPG or naphtha 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.

[0011] The "heat exchanger" in the anti-fouling method of the present disclosure is a heat exchanger used in the petroleum 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, etc. Examples of heat exchangers in the petroleum process in the present disclosure include, in one or more embodiments, heat exchangers in the petroleum refining process, or preheat exchangers in the petroleum process, etc.

[0012] In the heat exchanger of the petroleum process, it is considered that fouling is particularly likely to occur and accumulate in the high-temperature part of about 200 °C or higher. The anti-fouling method of the present disclosure can be preferably used, in one or more embodiments, to prevent fouling of heat exchangers having a high-temperature part that reaches about 200 °C or higher during treatment, for example, 180 °C, 190 °C, 200 °C, 210 °C, or 220 °C or higher. The anti-fouling method of the present disclosure can, in one or more embodiments, more effectively exhibit its anti-fouling effect in the part that has reached about 200 °C or higher.

[0013] FIG. 1 shows an example of a petroleum refining treatment apparatus in the petroleum process. The petroleum refining treatment apparatus in FIG. 1 is an example of a petroleum refining treatment apparatus including an atmospheric distillation column. As shown in FIG. 1, the petroleum refining treatment apparatus includes a pump 9, a preheater 1, a desalting apparatus 2, a preheater 3, a preflash tower 4, a preheater (heat exchanger) 5, a preheater (heat exchanger) 6, a heating furnace 7, an atmospheric distillation column 8, and a pump 10. The crude oil supplied through pump 9 is heated to 110°C - 140°C in preheater 1 and then sent to desalter 2 for desalting. Next, after being heated to 150°C - 180°C in preheater 3, it is sent to preflash tower 4. The low-boiling gas fraction separated in preflash tower 4 is discharged from the top of the tower, and the crude oil is discharged from the bottom of the tower. The discharged crude oil is heated to 240°C - 280°C by preheaters 5 and 6, then heated to 350°C - 360°C in heating furnace 7, and then introduced into atmospheric distillation column 8. In atmospheric distillation column 8, separation into fractions such as naphtha, kerosene, gas oil, and atmospheric residue is carried out according to the boiling range. The bottoms liquid discharged from the bottom of the column is sent as a heat source to preheaters 5 and 6 via pump 10.

[0014] In the present disclosure, "process fluid" refers to a liquid or gas used in an oil process. Examples of the process fluid include, in one or more embodiments, crude oil or hydrocarbons derived from crude oil processed in an oil process. In one or more embodiments where it is not particularly limited, examples of the process fluid include a liquid supplied to a preheater in an oil refining process or a liquid within a preheater.

[0015] In the present disclosure, "fouling" in the fouling prevention method refers to, in one or more embodiments where it is not limited, fouling containing organic polymer components such as asphaltene and sludge, or fouling containing organic polymer components such as asphaltene and sludge that adhere and / or accumulate in a heat exchanger.

[0016] In the present disclosure, "prevention of fouling of a heat exchanger" refers to, in one or more embodiments, suppressing the adhesion and / or deposition of fouling in a heat exchanger of an oil process. The fouling prevention method of the present disclosure may, in one or more embodiments where it is not particularly limited, include forming a film on the iron-based metal surface of the heat exchanger by treating the heat exchanger with a thiophosphate ester compound and a dispersant to prevent fouling from adhering to the heat exchanger.

[0017] [Fouling Prevention Method] In one aspect, the present disclosure relates to a method for preventing fouling of heat exchangers in petroleum processes (the fouling prevention method of the present disclosure). The fouling prevention method of the present disclosure includes adding a thiophosphate ester compound and a dispersant to a process fluid passing through a heat exchanger in a petroleum process.

[0018] In one or more embodiments, the fouling prevention method of the present disclosure uses a thiophosphate ester compound as one of the agents that function as an active ingredient contributing to the fouling prevention effect. Examples of the thiophosphate ester compound used in the fouling prevention method of the present disclosure include thiophosphate ester compounds used in petroleum processes in one or more embodiments.

[0019] Examples of the thiophosphate ester compound include, in one or more embodiments, a thiophosphate ester compound represented by the following formula (I). [Chemical formula] In formula (I), X 1 , X 2 , X 3 and X 4 are, independently of each other, an oxygen atom or a sulfur atom, and at least one of X 1 , X 2 , X 3 and X 4 is a sulfur atom. R 1 , R 2 and R 3 are, in one or more embodiments, independently of each other, a hydrogen atom or a group having 1 to 30 carbon atoms.

[0020] Examples of groups 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 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, an aralkyl group having 7 to 30 carbon atoms, an alkylaryl group having 7 to 30 carbon atoms, or a cycloalkyl group having 3 to 30 carbon atoms, and the like. The alkyl group, alkenyl group, aryl group, aralkyl group, alkylaryl group, and cycloalkyl group may or may not have a substituent in one or more embodiments.

[0021] In one or more embodiments, the alkyl group may be a straight-chain alkyl group or a branched-chain alkyl group. Examples of the alkyl group having 1 to 30 carbon atoms include, in one or more embodiments, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a decyl group, a dodecyl group, a tridecyl group, an octadecyl group, an eicosyl group, an isobutyl group, an isohexyl group, an isodecyl group, an isooctadecyl group, a neopentyl group, a 2-ethylhexyl group, and an oleyl group, and the like.

[0022] Examples of the alkenyl group having 2 to 30 carbon atoms include, in one or more embodiments, an ethenyl group, a 1-propenyl group, a 2-propenyl group, a 2-butenyl group, a 3-butenyl group, a pentenyl group, a 5-hexenyl group, and a dodecenyl group, and the like.

[0023] The aryl group may be monocyclic or bicyclic. Examples of the aryl group having 6 to 30 carbon atoms include, in one or more embodiments, a phenyl group, a 1-naphthyl group, or a 2-naphthyl group, and the like.

[0024] The aralkyl group refers to a group in which one or more hydrogen atoms of the alkyl group are substituted with an aryl group. Examples of the aralkyl group having 7 to 30 carbon atoms include, in one or more embodiments, a benzyl group, a benzhydryl group, and a trityl group, and the like.

[0025] An alkylaryl group refers to a group in which one or more hydrogen atoms of an aryl group are substituted with alkyl groups. Examples of alkylaryl groups having 7 to 30 carbon atoms include, in one or more embodiments, methylphenyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, octylphenyl group, methylbiphenyl group, and methylnaphthyl group, etc.

[0026] The cycloalkyl group may be monocyclic or bicyclic. Examples of cycloalkyl groups having 3 to 30 carbon atoms include, in one or more embodiments, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclopentenyl group, cyclohexyl group, and cyclohexenyl group, etc.

[0027] Examples of the thiophosphate ester compound include, in one or more embodiments, the thiophosphate ester compounds represented by the following formula (II) or (III).

Chemical formula

[0028] Examples of the thiophosphate ester compound include, in one or more embodiments, a thiophosphate monoester compound, a thiophosphate diester compound, and a thiophosphate triester compound. The thiophosphate monoester compound is, among the thiophosphate ester compounds of the above formulas (I) to (III), R 1 、R 2 and R 3 wherein two of them are hydrogen atoms and one is a group having a carbon atom. The thiophosphate diester compound is, among the thiophosphate ester compounds of the above formulas (I) to (III), R 1 、R 2 and R 3 wherein one of them is a hydrogen atom and two are groups having carbon atoms. The thiophosphate triester compound is, among the thiophosphate ester compounds of the above formulas (I) to (III), R 1 、R 2 and R 3 all three of which are groups having carbon atoms. The thiophosphate ester compound used in the stain prevention method of the present disclosure may be, in one or more embodiments, a mixture of two or three selected from thiophosphate monoesters, thiophosphate diesters, and thiophosphate triesters.

[0029] Examples of the thiophosphate monoester include, in one or more embodiments, the following compounds.

Chemical formula

[0030] Examples of the thiophosphate diester include, in one or more embodiments, the following compounds. [Chemical formula] In the above formula, R 1 and R 2 are, in one or more embodiments, independently of each other, a hydrogen atom or a group having 1 to 30 carbon atoms, preferably both are groups having 1 to 30 carbon atoms, more preferably both are the same alkyl group having 1 to 30 carbon atoms.

[0031] Examples of the triester of thiophosphoric acid include, in one or more embodiments, the following compounds. [Chemical formula] In the above formula, R 1 , R 2 and R 3 are, in one or more embodiments, independently of each other, a hydrogen atom or a group having 1 to 30 carbon atoms, preferably all three are groups having 1 to 30 carbon atoms, more preferably all three are the same, and are an aryl group having 6 to 30 carbon atoms without a substituent or an aryl group having 6 to 30 carbon atoms with a substituent.

[0032] The thiophosphoric acid ester compound may be, in one or more embodiments, an amine salt of a thiophosphoric acid ester. Examples of the amine salt of a thiophosphoric acid ester include, in one or more embodiments, the amine salt of a thiophosphoric acid ester represented by the following formula (IV). [Chemical formula] In the above formula (IV), R 1 , R 2 , R 3 , X 1 , X 2 , and X 3 are as described above, preferably X 1 , X 2 , and X 3 are hydrogen atoms, and R 1 , R2 and R 3 at least one of which is a hydrogen atom, or all are groups having the same number of carbon atoms of 1 to 30. R 4 is a group having 1 to 30 carbon atoms.

[0033] The thiophosphate ester compound used in the anti-fouling method of the present disclosure may, in one or more embodiments, be used alone or in combination of two or more.

[0034] The concentration of the thiophosphate ester compound in the process fluid supplied to the heat exchanger (the total concentration when using a plurality of types of thiophosphate ester compounds) may be, in one or more embodiments, 1 ppm to 100 ppm. The concentration of the thiophosphate ester compound in the process fluid may, in one or more embodiments, have a lower limit of 1 ppm or more, 2 ppm or more, or 3 ppm or more, and an upper limit of 100 ppm or less, 90 ppm or less, 80 ppm or less, or 50 ppm or less. 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 ester compound per 1 kg of the process fluid.

[0035] The anti-fouling method of the present disclosure includes, in one or more embodiments, adding a thiophosphate ester compound to the process fluid such that the concentration of the thiophosphate ester compound in the process fluid supplied to the heat exchanger is 1 ppm to 100 ppm.

[0036] [Dispersant] Examples of the dispersant used in the anti-fouling method of the present disclosure include dispersants that have been conventionally used or may be used in the future for preventing fouling in petroleum processes or heat exchangers in petroleum processes. Examples of the dispersant include, in one or more embodiments, polyolefin ester compounds, polyalkenyl-substituted succinic acid ester compounds, and succinimide compounds.

[0037] In one or more embodiments, the dispersant used in the anti-fouling method of the present disclosure may be used alone as one type, or may be used in combination of two or more types.

[0038] In one or more embodiments, the anti-fouling method of the present disclosure may include measuring the atomic weight ratio of hydrogen to carbon (H / C atomic ratio) in the fouling of the heat exchanger and adding a dispersant selected based on the measurement to the process fluid. By using the H / C atomic ratio as an index for the selection of the dispersant, effective chemical selection may be made possible. In one or more embodiments, when the H / C atomic ratio of the fouling of the heat exchanger exceeds 1.3, a succinimide compound is selected as the dispersant and added to the process fluid, and when the H / C atomic ratio of the fouling of the heat exchanger is 1.3 or less, a succinate compound is selected as the dispersant and added to the process fluid.

[0039] In one or more embodiments, the measurement of the H / C atomic ratio can be performed by 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, heat exchangers located immediately before the heating furnace or on the heating furnace side (downstream from the desalination device towards the heating furnace) of the desalination device, and heat exchangers with a high heating temperature (for example, heat exchangers 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. In one or more embodiments, the anti-fouling method of the present disclosure may include collecting fouling from the heat exchanger and obtaining the H / C atomic ratio from the collected fouling.

[0040] The concentration of the dispersant in the process fluid supplied to the heat exchanger (in the case of using multiple types of dispersants, the total concentration, and the same applies hereinafter) may be, in one or more embodiments, from 1 ppm to 100 ppm. The concentration of the dispersant in the process fluid may, in one or more embodiments, have a lower limit of 1 ppm or more, 2 ppm or more, or 3 ppm or more, and an upper limit of 100 ppm or less, 90 ppm or less, 80 ppm or less, or 50 ppm or less.

[0041] In one or more embodiments, the method for preventing fouling of the present disclosure includes adding a dispersant to the process fluid such that the concentration of the dispersant in the process fluid supplied to the heat exchanger is from 1 ppm to 100 ppm.

[0042] The ratio of the concentration of the dispersant to the concentration of the thiophosphate ester compound (concentration of the dispersant (ppm) / concentration of the thiophosphate ester compound (ppm)) may be, in one or more embodiments, from 0.2 to 5. The ratio may, in one or more embodiments, be from 0.3 to 3, or from 0.5 to 2.

[0043] In one or more embodiments, the method for preventing fouling of the present disclosure includes adding a dispersant to the process fluid such that the ratio of the concentration of the dispersant to the concentration of the thiophosphate ester compound is from 0.2 to 5.

[0044] In one or more embodiments, the location for adding the chemicals (thiophosphate ester compound and / or dispersant) to the process fluid in the method for preventing fouling of the present disclosure may be the location where the thiophosphate ester compound and the dispersant are introduced into the heat exchanger to be prevented from fouling. In one or more embodiments, the location for adding may be in front of the heat exchanger to be prevented from fouling, etc.

[0045] The order of adding the thiophosphate ester compound and the dispersant is not particularly limited. In one or more embodiments, they may be added simultaneously at the same location, separately at the same location, or added at different locations.

[0046] As the location for adding the chemical agent, in one or more embodiments where it is not particularly limited, examples include between the heat exchanger located upstream of the desalination device and the pump located upstream thereof, between the desalination device and the heat exchanger located downstream thereof, between the pre-flash tower and the heat exchanger located upstream thereof, and between the pump that introduces the bottoms liquid discharged from the bottom of the atmospheric distillation column into the heat exchanger and the heat exchanger located downstream thereof, etc.

[0047] When the heat exchangers 5 and 6 in the petroleum process shown in FIG. 1 are targeted by the fouling prevention method of the present disclosure, as the location for adding the chemical agent, in one or more embodiments, the locations of arrows A to D in FIG. 1 are examples. · Arrow A: Downstream of the heat exchangers 5 and 6 (between the pre-flash tower 4 and the heat exchanger 5) · Arrow B: Between the pump 10 and the heat exchanger 6 located downstream thereof · Arrow C: Between the heat exchanger 3 located downstream of the pre-flash tower 4 and the desalination device 2 · Arrow D: Between the heat exchanger 1 located in the distillation of the desalination device 2 and the pump 9 located upstream thereof

[0048] The fouling prevention method of the present disclosure may, in one or more embodiments, include an initial treatment at the time of restarting operation after regular cleaning or after an emergency stop. The initial treatment, in one or more embodiments, is to add a thiophosphate ester compound and / or a dispersant to the process fluid so as to have a concentration higher than that in the normal treatment (treatment during steady operation) at the time of restarting operation after regular cleaning or after an emergency stop, and to treat the surfaces of heat exchangers etc. with which the process fluid comes into contact at a chemical agent concentration higher than normal. As the concentration higher than normal, in one or more embodiments, the concentration (ppm) at the time of restarting operation is 1.5 times or more, 2 times or more, or 3 times or more the concentration (ppm) of the normal treatment. In one or more embodiments, the "steady operation" in the present disclosure refers to an operating state in which petroleum refining can be constantly performed at a desired production volume in the petroleum process (petroleum refining process). In one or more embodiments, the steady operation includes the ability to constantly refine (distill) a desired amount of crude oil in an atmospheric distillation unit (atmospheric distillation column) or a vacuum distillation unit.

[0049] [Anti-fouling agent] In one aspect, the present disclosure relates to an anti-fouling agent for use in the anti-fouling method of the present disclosure. The anti-fouling agent of the present disclosure contains a thiophosphate ester compound and a dispersant. In one or more embodiments, the anti-fouling agent of the present disclosure contains a thiophosphate ester compound as one of the active ingredients contributing to anti-fouling. The thiophosphate ester compound and the dispersant in the anti-fouling agent of the present disclosure are as described above.

[0050] In one or more embodiments, the form of the anti-fouling agent may be a solid such as powder or tablet, or may be in a state dissolved in a solvent, that is, in the form of a concentrated solution.

[0051] In one or more embodiments, the ratio (concentration ratio) of the concentration (weight %) of the thiophosphate ester compound (the total when containing multiple types of thiophosphate ester compounds) to the concentration (weight %) of the dispersant (the total when using multiple types of dispersants) in the anti-fouling agent in the present disclosure is 5:1 to 1:5, 3:1 to 1:3, or 2:1 to 1:2.

[0052] [Use] In one aspect, the present disclosure relates to the use of a thiophosphate ester compound in the anti-fouling method of the present disclosure. In other aspects, the present disclosure relates to the use of a thiophosphate ester compound to prevent fouling of a heat exchanger in a petroleum process through which a process fluid added with a dispersant passes. The thiophosphate ester compound, the dispersant, and their addition concentrations, etc. are as described above.

[0053] 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, comprising adding a thiophosphate compound and a dispersant to a process fluid passing through the heat exchanger. [2] The fouling prevention method according to [1], comprising adding the thiophosphate compound to the process fluid such that the concentration of the thiophosphate compound in the process fluid supplied to the heat exchanger is 1 ppm to 100 ppm. [3] The fouling prevention method according to [1] or [2], comprising adding the dispersant to the process fluid such that the ratio of the concentration of the dispersant to the concentration of the thiophosphate compound in the process fluid supplied to the heat exchanger (concentration of dispersant (ppm) / concentration of thiophosphate compound (ppm)) is 0.2 to 5. [4] A fouling preventive agent for use in the fouling prevention method according to any one of [1] to [3], comprising a thiophosphate compound and a dispersant.

[0054] Hereinafter, the present disclosure will be described in more detail by way of examples, which are illustrative only and the present disclosure is not limited to these examples.

Examples

[0055] [Chemical agents] Thiophosphate 1: Dioleyl thiophosphate·2-ethylhexylamine salt Thiophosphate 2: Alkylated triphenyl thiophosphate Thiophosphate 3: A mixture of tert-butylated triphenyl thiophosphate and triphenyl thiophosphate Succinimide: Polyalkenyl-substituted succinimide compound (bis type), molecular weight 10,000 Succinate: Polyalkenyl-substituted succinate compound, molecular weight 10,000

[0056] ​The molecular weight of the above compound 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 cross-linked gel Eluent: Tetrahydrofuran Flow rate: 0.7 ml / min Column temperature: 40 °C

[0057] [Preparation of agents] Preparation of thiophosphate ester formulation A: Thiophosphate ester 1 and dispersant (succinimide) were diluted in a solvent (heavy aromatic naphtha) so that their concentrations were 10 wt% and 20 wt%, respectively, to prepare thiophosphate ester formulation A. Preparation of thiophosphate ester formulation B: Thiophosphate ester 1 and dispersant (succinate) were diluted in a solvent (heavy aromatic naphtha) so that their concentrations were 10 wt% and 20 wt%, respectively, to prepare thiophosphate ester formulation B. Preparation of thiophosphate ester formulation C: Thiophosphate ester 2 and dispersant (succinimide) were diluted in a solvent (heavy aromatic naphtha) so that their concentrations were 10 wt% and 20 wt%, respectively, to prepare thiophosphate ester formulation C. Preparation of thiophosphate ester formulation D: Thiophosphate ester 3 and dispersant (succinimide) were diluted in a solvent (heavy aromatic naphtha) so that their concentrations were 10 wt% and 20 wt%, respectively, to prepare thiophosphate ester formulation D. Preparation of thiophosphate ester formulation E: Thiophosphate ester 1 was diluted in a solvent (heavy aromatic naphtha) so that its concentration was 10 wt% to prepare thiophosphate ester formulation E. Preparation of succinimide formulation: Succinimide was diluted in a solvent (heavy aromatic naphtha) so that its concentration was 10 wt% to prepare a succinimide formulation. Preparation of succinate formulation: The succinic acid ester compounded product was prepared by diluting it in a solvent (heavy aromatic naphtha) so that the concentration of the succinic acid ester became 10% by weight.

[0058] [Fouling prevention test] In order to examine the fouling prevention effect of a chemical used for fouling prevention in the petroleum refining process, a fouling prevention test was conducted. Specifically, the heating tube (heat rod) 21 shown in Fig. 2 was used as a test member for attaching fouling, the heating tube 21 was brought into contact with oil, and the fouling adhesion situation was measured. As shown in Fig. 2, the heating tube 21 is a mild steel tube used in a thermal stability tester defined in JIS K2276. The heating tube 21 has a constricted tube shape, with the end portions 21a and 21b having a large diameter and the intermediate portion 21c having a small diameter. As shown in Fig. 3, an inflow tube 23a and an outflow tube 23b are connected to the upper and lower portions of the heating tube holder 22, and the heating tube 21 is inserted into the central portion of the heating tube holder 22. A thermocouple 24 is inserted into the central portion of the heating tube 21, and a current can be passed through both end portions 21a and 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 tube 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) equipped with the above-described heating tube 21 and heating holder 22.

[0059] The heating tube 21 was heated under the following conditions by the test apparatus, and the sample was introduced from the inflow tube 23a to conduct the test. Sample: Prepared by adding to Crude Oil 1 and Crude Oil 2 such that the concentrations of the thiophosphate ester compound and the dispersant in Table 2 below are 20 ppm and 40 ppm, respectively. In the case of the thiophosphate ester compound and the dispersant alone, they were prepared by adding to Crude Oil 1 and Crude Oil 2 such that the concentrations were 60 ppm, respectively. The API, classification, and H / C atomic ratio of Crude Oil 1 and Crude Oil 2 are shown below. API is the specific gravity unit of crude oil defined by the American Petroleum Institute. Taking the specific gravity of water as 10, those less than 26° are classified as extra-heavy, 26 - 29.99° as heavy, 30 - 33.99° as medium, 34 - 39.99° as light, and those above 39° as extra-light. <Condition> Temperature of heating pipe 21: 330 - 340 °C (heating up over 20 minutes) Temperature of tank, line, and pump: 100 °C Sample volume: 200 ml (the tank is not partitioned and the sample circulates) Sample introduction flow rate: 1 ml / min System pressure: 500 - 600 psi (pressure adjustment with nitrogen) Test time: 5 hours

Table 1

[0060] The anti-fouling effect was evaluated according to the following evaluation criteria based on the change in the outlet temperature (Δt) of the sample. The results are shown in Table 2 below. 〔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 Δt, the more fouling adheres to the heating pipe 21. 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 10 D: Δt is 10 or more

[0061]

Table 2

[0062] As shown in Table 2, it was confirmed that sufficient anti-fouling effects were obtained in Examples 1 to 4 using thiophosphate ester formulations A to D. Under these test conditions, when the evaluation criterion was B or higher, it was considered that a sufficient anti-fouling effect was obtained. In Examples 1 to 4, it was confirmed that sufficient anti-fouling effects were obtained for Crude Oils 1 and 2. As shown in the above table, when the H / C atomic ratio of the fouling exceeded 1.3, by using succinimide as a dispersant, a better fouling adhesion suppression effect was obtained compared to the case of using succinic ester. Also, when the H / C atomic ratio of the fouling was 1.3 or less, by using succinic ester as a dispersant, a better fouling adhesion suppression effect was obtained compared to the case of using succinimide.

Claims

1. A method for preventing fouling of a heat exchanger in an oil process, comprising adding a thiophosphate ester compound and a dispersant to a process fluid passing through the heat exchanger, the heat exchanger in the oil process is a preheater for heating crude oil supplied to an atmospheric distillation column, The fouling prevention method, wherein the thiophosphate ester compound is a thiophosphate ester compound represented by the following formula (I). 【Chemical Formula 1】 In formula (I), X1, X2, X3 and X4 are each independently an oxygen atom or a sulfur atom, and at least one of X1, X2, X3 and X4 is a sulfur atom, R1, R2 and R3 are each independently a hydrogen atom or a group having 1 to 30 carbon atoms.

2. The fouling prevention method according to claim 1, comprising adding the thiophosphate ester compound to the process fluid so that the concentration of the thiophosphate ester compound in the process fluid supplied to the heat exchanger is 1 ppm to 100 ppm.

3. The fouling prevention method according to claim 1 or 2, comprising adding the dispersant to the process fluid so that the ratio of the concentration of the dispersant to the concentration of the thiophosphate ester compound (concentration of the dispersant (ppm) / concentration of the thiophosphate ester compound (ppm)) in the process fluid supplied to the heat exchanger is 0.2 to 5.

4. A fouling prevention agent for use in the fouling prevention method according to any one of claims 1 to 3, containing a thiophosphate ester compound and a dispersant, The fouling prevention agent, wherein the thiophosphate ester compound is a thiophosphate ester compound represented by the following formula (I). 【Chemical Formula 1】 In formula (I), X1, X2, X3, and X4 are, independently of one another, an oxygen atom or a sulfur atom, and at least one of X1, X2, X3, and X4 is a sulfur atom. R1, R2, and R3 are, independently of one another, a hydrogen atom or a group having 1 to 30 carbon atoms.

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