KR20190141778A - How to prevent contamination of heat exchangers in petroleum processes - Google Patents

Abstract

Provided are methods for preventing contamination of heat exchangers in petroleum processes. A method for preventing contamination of a heat exchanger in a petroleum process, the present invention relates to a pollution prevention method comprising adding a phosphite ester compound and a dispersant to a process fluid passing through the heat exchanger.

Description

How to prevent contamination of heat exchangers in petroleum processes

The present disclosure relates to a method for preventing contamination of a heat exchanger in a petroleum process.

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 transferred to a distillation column and distillation operation is performed. In a heat exchanger or in a furnace, the crude oil receives a heat history and a large amount of contamination is attached. As one form of contaminant, there is a form in which an organic polymer component called asphaltene is mixed. The adhesion of contamination causes a decrease in the heat exchange rate of the heat exchanger or the heating furnace, resulting in an increase in the amount of fuel used to maintain the outlet temperature.

Patent Literature 1 discloses a heat exchanger to be added to a process fluid before a desolder, a pollution inhibitor in a heating furnace, and a pollution prevention method. Moreover, patent document 2 discloses the method of preventing the contamination derived from asphaltene of the preheat bridge in a petroleum process using a phosphate ester anticorrosive agent and a dispersing agent.

Japanese Unexamined Patent Publication No. 2010-163539 WO2015 / 022979

MEANS TO SOLVE THE PROBLEM This inventor discovered that the phosphate ester type anticorrosive agent is especially useful for the prevention of contamination derived from asphaltene in a preheating bridge (patent document 2). However, as a result of using phosphate ester instead of the conventional antifouling agent, there existed a problem that corrosion by phosphate ester occurs in the carbon steel or stainless steel used for the storage tank of general antifouling agents, and chemical medicine facilities. In particular, the corrosiveness of the phosphate ester becomes remarkable with the increase in the temperature of the phosphate ester. At the high injection point, the temperature of the phosphate ester rises to approximately 200 ° C. For this reason, there is a problem that the conventional chemical equipment does not withstand the corrosion of phosphate ester, and the material of the chemical equipment needs to be changed to a corrosion resistant material.

The present disclosure, in one aspect, provides a new method capable of preventing contamination of heat exchangers in petroleum processes.

The present disclosure, in one aspect, relates to a pollution prevention method including adding a phosphite ester compound and a dispersant to a process fluid passing through the heat exchanger as a method for preventing contamination of a heat exchanger in a petroleum process.

In another aspect, the present disclosure relates to an antifouling agent containing a phosphite ester compound and a dispersant as an antifouling agent for use in the antifouling method of the present disclosure.

According to the present disclosure, contamination of the heat exchanger in the petroleum process can be suppressed. According to the present disclosure, in one or a plurality of embodiments, the corrosion of the storage tank of the antifouling agent and the medicine pouring facility can be suppressed.

1 is a block diagram showing an example of a petroleum refining apparatus equipped with an atmospheric distillation column.
2 is a cross-sectional view of a heating tube used for a pollution prevention test.
3 is a cross-sectional view of a state in which a heating tube is inserted into a heating tube holder.

This indication is based on the knowledge that the contamination in heat exchangers, such as a preheating bridge of a petroleum process, can be prevented by using a phosphite ester compound and a dispersing agent together. Moreover, this indication is based on the knowledge that the corrosion of chemical | medical-weakness installation which generate | occur | produces when a phosphate ester type anticorrosive agent is used as a pollution prevention agent can be reduced by changing into a phosphate ester type anticorrosive agent and using a phosphite ester compound.

According to the present disclosure, in one or a plurality of embodiments, contamination of heat exchangers such as preheating bridges in the petroleum process can be prevented, and the heat exchange rate of the heat exchanger can be improved / maintained. Fuel costs and cleaning costs can be reduced. In addition, according to the present disclosure, in one or a plurality of embodiments, it is possible to prevent contamination in the heat exchanger of the petroleum process using a conventional medicine facility without changing the medicine facility.

In the pollution prevention method of the present disclosure, details that can prevent contamination in a heat exchanger, particularly a preheating bridge, are not clear, but the mechanism is estimated as follows. That is, as one of the causes of the contamination, sulfur atoms of asphaltenes are formed by forming sulfides on the surface of the heat exchanger. When the phosphite ester compound and the dispersant are added, the phosphite ester compound and / or the phosphorous acid decomposed under high temperature It is considered that the coating by the ester compound is formed on the surface of the heat exchanger and the formation of sulfides on the surface of the heat exchanger can be suppressed by the coating. However, the present disclosure need not be limited to these ways of thinking.

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 therefrom. The petroleum process, in one or a plurality of embodiments, heats hydrocarbons such as crude oil, various types of gas such as LPG, gasoline such as naphtha, diesel, etc. by using the difference of boiling points in the atmospheric distillation apparatus. At least separating into components. The petroleum process in the present disclosure may include a petroleum refining process in one or a plurality of embodiments.

In the pollution prevention method of this disclosure, a "heat exchanger" is a heat exchanger used for a petroleum process. As a heat exchanger, in one or some embodiment which is not limited, a preheat bridge (also called a preheating heat bridge or a preheat exchanger), a preheater, a reboiler, etc. are mentioned. In these heat exchangers, in particular, a part where contamination is likely to occur and accumulate is a high temperature part of about 200 ° C or more. The pollution prevention method of the present disclosure, in one or a plurality of embodiments, includes at least about 200 ° C, for example, at least 180 ° C, at least 190 ° C, at least 200 ° C, at least 210 ° C, or at least 220 ° C at the time of treatment. This is a method for preventing contamination of heat exchangers with hot parts. The pollution prevention method of the present disclosure more effectively exhibits the pollution prevention effect at about 200 ° C. or higher in one or a plurality of embodiments.

As a heat exchanger in a petroleum process, in one or some embodiment, the heat exchanger of a petroleum refining process, the preheating bridge of a petroleum process, etc. are mentioned.

In the present disclosure, the "process fluid" refers to a liquid or gas provided in a petroleum process. As a process fluid, in one or some embodiment, the crude oil processed in a petroleum process, the hydrocarbon derived from these, etc. are mentioned. As a process fluid, in one or some embodiment which is not specifically limited, the liquid supplied to a preheat bridge in the petroleum refining process, the liquid in a preheat bridge, etc. are mentioned.

In the pollution prevention method of the present disclosure, "pollution" refers to containing asphaltene (asphaltene) in one or a plurality of embodiments, but is not limited to, or ass deposited and / or accumulated in a heat exchanger. Refers to contamination involving the Palten. Therefore, contamination prevention in the heat exchanger in this indication is suppression of adhesion and / or accumulation of asphaltene in a heat exchanger in one or some embodiment.

[Pollution Prevention Method]

In one aspect, the present disclosure includes adding a phosphite ester compound and a dispersant to a process fluid that passes through a heat exchanger in a petroleum process (method of preventing the heat exchanger in a petroleum process). Pollution prevention method).

Phosphoric Acid Ester Compound

As a phosphite ester compound used in the pollution prevention method of this indication, the phosphite ester compound used in a petroleum process in one or some embodiment is mentioned.

As a phosphite ester compound, in one or some embodiment which is not specifically limited, a phosphonic acid type phosphite ester compound, a phosphite type phosphite ester compound, a diphosphite type phosphite ester compound, etc. are mentioned. As a phosphonic acid type phosphite ester compound, the phosphite ester compound represented by Formula (I) is mentioned. As a phosphorous acid type phosphorous acid ester compound, the phosphorous acid ester compound represented by Formula (II) is mentioned. As a diphosphite type phosphite ester compound, the thing containing two structures of Formula (II) in one or some embodiment, or the dimer (dimer) of the compound of Formula (II), etc. are mentioned. As a diphosphite type phosphite ester compound, the compound represented by Formula (III) or (IV) in one or some embodiment is mentioned.

[Formula 1]

In Formula (I), R <^1> and R <^2> is the same or different, and is group which has 1-30 carbon atoms. In Formula (II), R <^3> , R <^4> and R <^5> is the same or different, and is group which has 1-30 carbon atoms. In formula (III), R <^6> , R <^7> and R <^8> is the same or different, is a group which has 1-30 carbon atoms, and X <^1> is an oxygen atom or a carbon atom. In formula (IV), R <^9> and R <^10> is the same or different, is a group which has 1-30 carbon atoms, and X <^2> is a carbon atom.

As a group which has 1-30 carbon atoms, in one or some embodiment, C1-C30 alkyl group, C1-C30 alkenyl group, C6-C30 aryl group, C7 or more An aralkyl group of 30 or less, or an alkylaryl group of 7 to 30 carbon atoms is mentioned. The alkyl group, alkenyl group, aryl group, aralkyl group and alkylaryl group may have a substituent in one or some embodiment. In one or some embodiment, an alkyl group may be a linear alkyl group, or a branched chain alkyl group may be sufficient as it.

In Formula (I), although R <^1> and R <^2> may be same or different, it is preferable that R <^1> and R <^2> are the same. In Formula (II), although R <^3> , R <^4> and R <^5> may be same or different, It is preferable that R <^3> , R <^4> and R <^5> are the same. In Formula (III), although R <^6> and R <^8> may be same or different, It is preferable that R <^6> and R <^8> are the same.

As a phosphite ester compound, in one or some embodiment,

Triphenyl phosphite, Trisnonyl phenyl phosphite, Tricresyl phosphite, Triethyl phosphite, Tris (2-ethylhexyl) phosphite, Tridecyl phosphite, Trilauryl phosphite, Tris (tridecyl) phosph Fight, Trioleyl Phosphite, Tristearyl Phosphite, Diphenyl Mono (2-ethylhexyl) Phosphite, Diphenyl Monodecyl Phosphite, Diphenyl Mono (tridecyl) Phosphite, Tris (2,4-di -tert-butylphenyl) phosphite;

Diethylhydrogenphosphite, bis (2-ethylhexyl) hydrogenphosphite, dilaurylhydrogenphosphite, dioleylhydrogenphosphite, diphenylhydrogenphosphite;

Tetraphenyldipropylene glycol diphosphite, tetra (C12-15 alkyl) -4,4'-isopropylidenediphenyldiphosphite, a mixture of bis (tridecyl) pentaerythritoldiphosphite and bis (nonylphenyl) pentaerythritoldiphosphite , Bis (tridecyl) pentaerythritol diphosphite, bis (decyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite;

Tetraphenyl (tetratridecyl) pentaerythritol tetraphosphite, hydrogenated bisphenol A pentaerythritol phosphate polymer, or

A combination of these.

As the phosphite ester compound, in one or a plurality of embodiments, triphenylphosphite, trisno, from the viewpoint of further contamination prevention of the heat exchanger in the petroleum process and / or further corrosion inhibition of the storage tank or the chemical equipment Nylphenyl 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) force Pit, Diethylhydrogenphosphite, Bis (2-ethylhexyl) hydrogenphosphite, Dilaurylhydrogenphosphite, Dioleylhydrogenphosphite, Diphenylhydrogenforce The site, or a combination thereof are preferred. As a phosphite ester compound from a similar viewpoint, a phosphonic acid type phosphite ester compound is preferable, and diethyl-hydrogen phosphite, bis (2-ethylhexyl) hydrogen phosphite, a dilauryl hydrogen phosphite, a dioleylhydrogen More preferred is phosphite, diphenylhydrogenphosphite or a combination thereof.

A phosphorous acid ester compound may be used by one type in one or some embodiment, and may be used in combination of multiple types.

As a density | concentration of the phosphite ester compound in the process fluid supplied to a heat exchanger, 1-100 ppm, 2-80 ppm, or 3-50 ppm is mentioned in one or some embodiment. In the pollution prevention method of the present disclosure, in one or a plurality of embodiments, the concentration of phosphite ester in the process fluid supplied to the heat exchanger is 1 to 100 ppm, 2 to 80 ppm, or 3 to 50 ppm. And adding phosphite ester to the process fluid.

[Dispersant]

As a dispersant which can be used in the pollution prevention method of this indication, what is conventionally used as a pollution prevention of a petroleum process or the heat exchanger of a petroleum process, or what can be used in the future is mentioned. Dispersants that can be used in the pollution prevention method of the present disclosure include, in one or more embodiments, polyolefin esters, polyalkenyl substituted succinic acid esters, or combinations thereof.

As a density | concentration of the dispersing agent in the process fluid supplied to a heat exchanger, 1-100 ppm, 2-80 ppm, or 3-50 ppm is mentioned in one or some embodiment. The pollution prevention method of the present disclosure is, in one or a plurality of embodiments, the process fluid such that the dispersant in the process fluid supplied to the heat exchanger is 1 to 100 ppm, 2 to 80 ppm, or 3 to 50 ppm. Adding a dispersant to the.

As a ratio of content (ppm) of the phosphite ester compound and a dispersing agent in a process fluid supplied to a heat exchanger, in one or some embodiment, it is 5: 1-1: 1, 5: 1-3: 1, Or 2: 1 to 1: 2. In the pollution prevention method of the present disclosure, in one or a plurality of embodiments, the ratio of the content (ppm) of the phosphite ester compound and the dispersant in the process fluid supplied to the heat exchanger is 5: 1 to 1: 5,3 It adds a phosphite ester compound and a dispersing agent to a process fluid so that it may be 1: 1: 3 or 2: 1: 1: 2.

The place where a phosphite ester compound and a dispersing agent are added to a process fluid is not specifically limited, In one or some embodiment, the place where the said phosphate ester compound and a dispersing agent can be introduce | transduced into the heat exchanger which is a pollution prevention object. Or in front of the target heat exchanger. The addition order of a phosphite ester compound and a dispersing agent is not specifically limited, In one or some embodiment, they may be added simultaneously, may be added separately, and may be added in a mutually different place.

1 is a block diagram showing an example of a petroleum refining apparatus equipped with an atmospheric distillation column. In this petroleum refining apparatus, the crude oil supplied through the pump 6 is desalted in the desalination apparatus 1, and then heated to 150 to 180 ° C. in the preheating bridge 2 (heat exchanger 2) and further added. It is introduced into the preheating bridge 3 (heat exchanger 3), heated to 240 to 280 ° C, heated to 350 to 380 ° C in the heating furnace 4, and introduced to the atmospheric distillation column 5. Residual oil from the bottom of the column of the atmospheric distillation column 5 is sent as a heat source to the heat exchangers 3 and 2 via the pump 7.

When implementing the pollution prevention method of this indication in the heat exchanger 3 of the petroleum process of FIG. 1, as a addition place of a phosphite ester compound and a dispersing agent, in one or some embodiment which is not limited, a heat exchanger Although the place shown by the arrow A of FIG. 1 which is before (3) is mentioned, the place shown by the arrow C of the further front may be sufficient. In the heat exchanger 3 of FIG. 1, when implementing the pollution prevention method of this indication from the heating side, as a addition place of a phosphite ester compound and a dispersing agent, in one or some embodiment which is not limited, heat | fever The place shown by the arrow B of FIG. 1 in front of the exchanger 3 is mentioned.

[Pollution inhibitor]

The present disclosure, in one aspect, relates to an antifouling agent containing a phosphite ester and a dispersant as an antifouling agent for use in the antifouling method of the present disclosure. In one or some embodiment, the form of the antifouling agent of this aspect may be solid, such as powder and a tablet, and may be in the state melt | dissolved in the solvent, ie, the form of a concentrated liquid.

[use]

In one aspect, the present disclosure relates to the use of a phosphite ester compound in the pollution prevention method of the present disclosure. Moreover, this indication relates to use of the phosphite ester compound in another aspect in order to prevent contamination of the heat exchanger of the petroleum process through which the process fluid to which a dispersing agent was added passes. It is as having mentioned above as a phosphite ester compound.

The present disclosure may relate to one or a plurality of embodiments below;

[1] A method of preventing contamination of heat exchangers in petroleum processes,

Adding a phosphite ester compound and a dispersant to the process fluid passing through said heat exchanger.

[2] The contamination prevention method according to [1], which further comprises adding the phosphite ester compound to the process fluid so that the concentration of the phosphite ester compound in the process fluid supplied to the heat exchanger is 1 to 100 ppm.

[3] The pollution prevention method according to [1] or [2], comprising adding the dispersant to the process fluid so that the concentration of the dispersant in the process fluid supplied to the heat exchanger is 1 to 100 ppm.

[4] the phosphite ester compound so that the ratio (phosphite ester compound: dispersant) of the content (ppm) of the phosphite ester compound and the dispersant in the process fluid supplied to the heat exchanger is 5: 1 to 1: 5; The pollution prevention method according to any one of [1] to [3], comprising adding the dispersant to the process fluid.

[5] The pollution prevention method according to any one of [1] to [4], wherein the pollution prevention includes inhibiting adhesion and / or accumulation of asphaltene in the heat exchanger.

[6] An antifouling agent for use in the antifouling method according to any one of [1] to [5], wherein the antifouling agent contains a phosphite ester compound and a dispersant.

[7] Use of a phosphite ester compound to prevent contamination of the heat exchanger of a petroleum process through which process fluid with a dispersant is passed.

Although this indication is demonstrated according to the following Example and a comparative example, this indication is not limited to this.

Example

[Test piece]

The following two types of test pieces were prepared.

Carbon steel: 10 mm × 60 mm × 1 mm, SPCC, 7.85 g / cm 3

Stainless steel: 10 mm × 60 mm × 1 mm, SUS304, 7.93 g / cm 3

[drugs]

The following drugs were prepared.

Phosphoric acid ester compound A: Phosphoric acid ester A (phosphonic acid type phosphorous acid ester compound) and a dispersing agent

Phosphoric acid ester compound B: Phosphoric acid ester B (phosphonic acid type phosphorous acid ester compound) and a dispersing agent

Phosphoric acid ester compound C: Contains phosphorous acid ester C (phosphorous acid ester compound of phosphorous acid type) and a dispersing agent

Phosphoric acid ester compound D: Contains phosphorous acid ester D (phosphorous acid ester compound of phosphorous acid type) and a dispersing agent

Phosphoric acid ester compound E: Phosphoric acid ester A (phosphonic acid type phosphorous acid ester compound), phosphorous acid ester C (phosphorous acid type phosphorous acid ester compound), and a dispersing agent

Phosphate ester formulation: Contains phosphate ester and dispersant used as anticorrosive for high temperature

Phosphoric acid ester A, phosphorous acid ester B, phosphorous acid ester C, and phosphorous acid ester D are respectively different phosphorous acid ester compounds. As the dispersant, polyolefin ester was used.

<Preparation method of mixture>

Each compound A-D was adjusted so that heavy phosphate naphtha could be used as a solvent, and said phosphite ester or phosphate ester and a dispersing agent might be 30 weight%, respectively at the ratio of 1: 1 (weight ratio). The phosphite ester blended product E was adjusted so that the equivalent mixture of the phosphite ester A and the phosphite ester C and the dispersant were 30% by weight, respectively, at a ratio of 1: 1 (weight ratio).

[Corrosion effect confirmation examination 1]

The anticorrosive effect confirmation test was done in the following procedures using the test piece made from carbon steel. First, 100 ml of the medicine of Table 1 was put in a 100 ml screw tube. After performing acetone degreasing and drying, the test piece which measured the total weight was put in the screw tube, the lid was covered, and it left still for 7 days in a 50 degreeC thermostat.

[evaluation]

After completion of the test, the test piece was recovered, red rust was removed by 15% aqueous hydrochloric acid solution and tap water, and the corrosion degree (MDD) and erosion degree (mm / y) were calculated from the following equation from the weight difference between the test pieces before and after the test. . The results are shown in Table 1 below.

Corrosion degree (MDD) = (M ₁ -M ₂ ) / (S × T)

Erosion Degree (mm / y) = MDD × {365 × 10 ^-4 } / d

M ₁ : mass before test of test piece (mg)

M ₂ : Mass after test of the test piece (mg)

S: surface area of the test piece (dm ² )

T: test days

d: density of test piece (g / cm 3)

As shown in Table 1, in Comparative Example 1 using the phosphate ester blended product, corrosion of carbon steel occurred. On the other hand, in Examples 1-5 which used the phosphite ester compound, the corrosion of carbon steel was not confirmed at all.

[Corrosion effect confirmation examination 2]

The anticorrosive effect confirmation test was done in the following procedures using the test piece of stainless steel.

In order to carry out the test at 150 ° C, the oxidation stability tester described in JIS K 2276 (petroleum product-aviation fuel oil test method), the test method, and the spring package and the test vessel set were used. First, 100 ml of the following chemical | medical agents were put into the glass test container. After acetone degreasing and drying, the test piece, which has been weighed in its entirety, is placed in a test container and covered with a cover.In order to nitrogen-substitute the oxygen in the bomb, it is put in a cylinder and injected with nitrogen at 0.5 MPa. The process was repeated three times and sealed at the third time while injecting nitrogen. The bomb after nitrogen substitution was put into the oxidation stability tester, and it left still for 3 days in 150 degreeC thermostat. The evaluation similar to the anticorrosive effect confirmation test 1 was implemented after completion | finish of a test. The results are shown in Table 2 below.

As shown in Table 2, in Comparative Example 2 using the phosphate ester blended product, corrosion of stainless steel occurred. On the other hand, in Examples 6-10 which used the phosphite ester compounded product, the corrosion of stainless steel was not confirmed at all.

[Pollution (fouling) prevention test]

The pollution (fouling) prevention test is a test for investigating the antifouling effect of the petroleum refining antifouling agent, and uses a heating tube (heat rod) 21 shown in FIG. 2 as a test member for adhering contamination. This is carried out by bringing the heating tube into contact with oil and measuring the adhesion state of the contamination. This heating tube 21 is used for the thermal stability tester prescribed | regulated to JISK2276, and it is mild steel, and the edge part 21a, 21b became large diameter, and the middle part 21c became narrow diameter, and became narrowed. It has a tubular shape. This heating tube 21 is inserted in the tubular heating tube holder 22 shown in FIG. The inlet pipe 23a and the outlet pipe 23b are connected to the upper part and the lower part of the heating tube holder 22, and the thermocouple 24 is inserted in the center part of the heating tube 21, The thermostat which is not shown in figure This makes it possible to flow an electric current from both parts 21a and 21b of the heating tube 21 so that the temperature sensed by the thermocouple 24 becomes a predetermined temperature. As the test apparatus, a Hot Liquid Process Simurator tester manufactured by Alcor Co., Ltd. having the heating tube 21 described above was used.

By the said test apparatus, the heating pipe 21 was heated like the following conditions, the sample was introduce | transduced from the inflow pipe 23a, and the test was done.

Sample: The drugs of Table 3 below were prepared by adding a dispersant, a phosphite ester compound or a phosphate ester to 10 ppm with respect to the crude oil sample.

Temperature of the heating tube 21: 360 degreeC (heating up to 360 degreeC over 20 minutes)

Tank, line and pump temperature: 100 ℃

Sample volume: 500 ml (samples returned from the tank are not mixed) Sample introduction flow rate: 1 ml / min

Pressure in the system: 500 psi (adjust pressure with nitrogen)

Exam time: 5 hours

The antifouling effect was evaluated based on the following evaluation criteria based on the outlet temperature change (Δt) of the sample. The results are shown in Table 3 below.

[Outlet temperature change of sample: Δt]

The temperature change (Δt) of the sample temperature of the highest temperature after the test start in the outflow pipe 23b (heating part outlet) and the sample temperature after 5 hours passed was measured. The more the contamination adheres to the heating tube 21, the larger the Δt.

Evaluation criteria A: Δt is less than 8

          B: Δt is 8 or more and less than 15

          C: Δt is 15 or more

As shown in Table 3, Examples 11 and 12 using the phosphite ester blended product were able to suppress adhesion of contamination at the same level as Reference Example 1 using the phosphate ester blended product. In short, it was confirmed that contamination of the heat exchanger in the petroleum process can be sufficiently prevented by using a phosphite ester and a dispersant in combination.

Claims (7)

As a method for preventing contamination of heat exchangers in petroleum processes,
Adding a phosphite ester compound and a dispersant to the process fluid passing through said heat exchanger. The method of claim 1,
A method for preventing contamination, comprising adding the phosphite ester compound to the process fluid so that the concentration of the phosphite ester compound in the process fluid supplied to the heat exchanger is 1 to 100 ppm. The method according to claim 1 or 2,
And adding the dispersant to the process fluid so that the concentration of the dispersant in the process fluid supplied to the heat exchanger is 1 to 100 ppm. The method according to any one of claims 1 to 3,
Adding the phosphite ester compound and the dispersant to the process fluid such that the ratio of the content (ppm) of the phosphite ester compound and the dispersant in the process fluid supplied to the heat exchanger is 5: 1 to 1: 5. Containing, pollution prevention method. The method according to any one of claims 1 to 4,
The contamination prevention method includes preventing adhesion and / or accumulation of asphaltenes in a heat exchanger. An antifouling agent for use in the antifouling method according to any one of claims 1 to 5, wherein the antifouling agent contains a phosphite ester compound and a dispersant. Use of phosphite ester compounds to prevent contamination of heat exchangers in petroleum processes through which process fluids with dispersants are passed.

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