JP7577506B2 - Fouling inhibitor for feedstock oil preheating heat exchanger in petroleum refining process, feedstock oil for petroleum refining process, and method for inhibiting fouling of feedstock oil preheating heat exchanger in petroleum refining process - Google Patents

Description

The present invention relates to a fouling inhibitor for a heat exchanger for preheating raw oil in an oil refining process, raw oil for an oil refining process, and a method for inhibiting fouling of a heat exchanger for preheating raw oil in an oil refining process.

In the petroleum refining process, crude oil and various heavy oils are used as feedstock oils and are refined at high temperatures in various refining units, such as atmospheric distillation units, vacuum distillation units, fluid catalytic cracking units (FCC), direct desulfurization units, and indirect desulfurization units. In order to improve the processing efficiency of each unit, the feedstock oil to be processed is preheated in a heat exchanger before being sent to each unit.

For example, among the refining equipment mentioned above, a fluid catalytic cracker (FCC) is a device that brings heavy oil into contact with a fluid catalytic cracking catalyst at high temperatures of 500°C or higher to crack the heavy oil and produce gasoline fractions and middle distillates. The heavy oil to be processed by the fluid catalytic cracker includes desulfurized heavy oil, thermally desulfurized heavy oil, indirectly desulfurized heavy oil, and directly desulfurized heavy oil. These heavy oils are preheated to around 300°C in a heat exchanger (or in some cases, a heat exchanger and a heating furnace) before being fed into the fluid catalytic cracker.

Japanese Patent Application Publication No. 11-102204

However, the inventors' investigations revealed that, as mentioned above, the raw oils to be treated (crude oil and various heavy oils) contain very heavy components, and therefore preheating using a heat exchanger tends to result in deposits (dirt) adhering to the heat exchange parts, reducing the heat exchange efficiency. If the heat exchange efficiency decreases, the crude oil and heavy oil fed into the various refining equipment will not be sufficiently heated, and more energy will be required for processing in the refining equipment. This means that it will be necessary to preheat the oil in a separate heating furnace, or, if there is no heating furnace, to reduce the processing volume of the refining equipment, which will increase production costs and reduce productivity.

Under these circumstances, the present invention aims to provide a fouling inhibitor for a heat exchanger used to preheat raw oil in an oil refining process that can sufficiently suppress adhesion of fouling to a preheating heat exchanger, a raw oil for use in an oil refining process, and a method for suppressing fouling for a heat exchanger used to preheat raw oil in an oil refining process.

After extensive research to solve the above technical problems, the inventors came up with the idea that by using a dirt inhibitor that dissolves the components that cause dirt that adheres to the preheating heat exchanger, it would be possible to either inhibit the adhesion of dirt to the heat exchanger walls or to effectively dissolve dirt that has already adhered.

Based on the above findings, the present inventors have further studied and found that the above object can be achieved by a fouling inhibitor for a heat exchanger for preheating raw oil in a petroleum refining process, the fouling inhibitor being made of an aromatic compound having a boiling point of 200° C. or higher, in which the ratio (Ra/R 0 ) of the Hansen solubility parameter distance Ra with respect to the fouling adhering to the preheating heat exchanger to the interaction radius R ₀ , which is the radius of the Hansen sphere defined by the Hansen solubility parameters of a pure substance that is soluble in the fouling adhering to the preheating heat exchanger and the Hansen solubility parameters of a pure substance that is not soluble in the fouling adhering to the preheating heat exchanger, is 1.0 or _less in a Hansen solubility parameter space defined by plotting the Hansen solubility parameters in a three-dimensional space, and have completed the present invention based on this finding.

That is, the present invention provides
(1) A fouling inhibitor for a heat exchanger for preheating raw oil in a petroleum refining process, comprising:
In the Hansen solubility parameter space defined by plotting the Hansen solubility parameters in a three-dimensional space,
The interaction radius R 0 is the radius of a Hansen sphere defined by the Hansen solubility parameters of a pure substance that is soluble in the dirt adhering to the preheating heat exchanger and the Hansen solubility parameters of a pure substance that is _not soluble in the dirt adhering to the preheating heat exchanger.
The ratio (Ra/R ₀ ) of the Hansen solubility parameter distance Ra to the dirt adhering to the preheating heat exchanger is 1.0 or less;
A fouling inhibitor for a heat exchanger for preheating raw oil in a petroleum refining process, comprising an aromatic compound having a boiling point of 200°C or higher;
(2) The fouling inhibitor for a heat exchanger for preheating raw oil in the petroleum refining process is represented by the following general formula (I):

(wherein R ¹ is a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms, R ² and R ³ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms and may be the same or different, and the total number of carbon atoms of R ¹ , R ² and R ³ is 0 to 15.)
and a compound represented by the following general formula (II):

(Note that R ⁴ and R ⁵ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms, and may be the same or different, and the total number of carbon atoms in R ⁴ and R ⁵ is 0 to 10.)
and a compound represented by the following general formula (III):

(Note that R ⁶ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, R ⁷ and R ⁸ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms and may be the same or different, and the total number of carbon atoms of R ⁶ , R ⁷ and R ⁸ is 0 to 10.)
and a compound represented by the following general formula (IV):

(Note that R ⁹ and R ¹⁰ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms, and may be the same or different, and the total number of carbon atoms in R ⁹ and R ¹⁰ is 0 to 10.)
a compound represented by the following general formula (V):

(Note that R ¹¹ is a hydrocarbon group having 1 to 10 carbon atoms, R ¹² and R ¹³ are hydrogen atoms or hydrocarbon groups having 1 to 5 carbon atoms and may be the same or different, and the total number of carbon atoms of R ¹² and R ¹³ is 0 to 5.)
and a compound represented by the following general formula (VI):

(Note that R ¹⁴ to R ²⁰ are hydrogen atoms or hydrocarbon groups having 1 to 3 carbon atoms, and may be the same or different, and the total number of carbon atoms of R ¹⁴ to R ²⁰ is 0 to 10.)
The fouling inhibitor for a heat exchanger for preheating raw oil in a petroleum refining process according to the above (1), which is one or more compounds selected from the group consisting of compounds represented by the following formula:
(3) A feedstock oil for a petroleum refining process, comprising a feedstock oil containing 100 ppm by mass to 5000 ppm by mass of the stain inhibitor according to (1) or (2) above;
(4) A method for inhibiting fouling of a heat exchanger for preheating feed oil in an oil refining process, comprising the steps of:
The present invention provides a method for inhibiting fouling of a heat exchanger for preheating a raw oil in a petroleum refining process, the method comprising: supplying a raw oil containing 100 ppm by mass to 5,000 ppm by mass of the fouling inhibitor according to (1) or (2) above to the heat exchanger for preheating the raw oil.

According to the present invention, it is possible to provide a fouling inhibitor for a heat exchanger for preheating raw oil in an oil refining process that exhibits excellent solubility for fouling particles adhering to the heat exchanger for preheating raw oil, and that can sufficiently suppress the adhesion of fouling particles to the heat exchanger for preheating raw oil in an oil refining process, as well as a fouling inhibitor for a heat exchanger for preheating raw oil in an oil refining process.

FIG. 13 is a diagram for explaining how to determine the HSP value (δd _m , δp _m , δh _m ) that constitutes the central value of the Hansen sphere. FIG. 2 is a conceptual diagram showing the relationship between the HSP value of the contaminants adhering to the preheating heat exchanger, the HSP value of the raw oil base material, and the Hansen solubility parameter distance Ra in the Hansen solubility parameter space. FIG. 2 is a conceptual diagram illustrating a method for measuring the temperature difference over time of the feed oil temperature at the heater outlet.

The fouling inhibitor for a feed oil preheating heat exchanger in an oil refining process according to the present invention comprises:
In the Hansen solubility parameter space defined by plotting the Hansen solubility parameters in a three-dimensional space,
The interaction radius R 0 is the radius of a Hansen sphere defined by the Hansen solubility parameters of a pure substance that is soluble in the dirt adhering to the preheating heat exchanger and the Hansen solubility parameters of a pure substance that is _not soluble in the dirt adhering to the preheating heat exchanger.
The ratio (Ra/R ₀ ) of the Hansen solubility parameter distance Ra to the dirt adhering to the preheating heat exchanger is 1.0 or less;
It is characterized by being made of an aromatic compound having a boiling point of 200° C. or higher.

Examples of heat exchangers for preheating feedstock oil in the petroleum refining process to which the fouling inhibitor of the present invention is applicable include heat exchangers for preheating feedstock oil for atmospheric distillation units, heat exchangers for feedstock oil for vacuum distillation units, heat exchangers for preheating feedstock oil for fluid catalytic cracking units (FCC), heat exchangers for preheating feedstock oil for direct desulfurization units, and heat exchangers for preheating feedstock oil for indirect desulfurization units, and it is appropriate that the heat exchanger is a heat exchanger for preheating feedstock oil for a fluid catalytic cracking unit (FCC).

The feedstock oils (crude oil and various heavy oils) supplied to each oil refining process are appropriately selected from those conventionally known.

The fouling inhibitor according to the present invention has an interaction radius R 0 , which is the radius of a Hansen _sphere defined by the Hansen solubility parameters of a pure substance that is soluble in the fouling adhering to the preheating heat exchanger and a pure substance that is not soluble in the fouling adhering to the preheating heat exchanger, and
The ratio (Ra/R ₀ ) of the Hansen solubility parameter distance Ra to the contaminants adhering to the preheating heat exchanger is 1.0 or less.

In this application, the Hansen solubility parameter (HSP) refers to a vector parameter obtained by dividing the Hildebrand solubility parameter into three cohesive energy components, namely, the London dispersion force, the dipole-dipole force, and the hydrogen bond force.
In this application, the component corresponding to the London dispersion force of HSP is represented as the dispersion term δd _m , the component corresponding to the dipole-dipole force of HSP is represented as the polar term δp _m , and the component corresponding to the hydrogen bonding force of HSP is represented as the hydrogen bonding term δh _m .
In the present application, the Hansen solubility parameter value (HSP value) is expressed as ( _δdm , _δpm , _δhm ). In addition, in the present application, the Hansen solubility parameter value (HSP value) means the HSP value at 25°C.

Because HSPs are vector quantities, there are almost no pure substances that have exactly the same values. Furthermore, databases of HSP values of commonly used substances have been constructed, so that a person skilled in the art can obtain the HSP value of a desired substance by referring to the database.
Furthermore, even if the HSP value of a substance is not registered in the database, a person skilled in the art can calculate the HSP value.

The HSP value of an evaluation sample having an unknown HSP value can be calculated by the following method.
In the Hansen Solubility Parameter space specified by plotting the HSP values ( _δdm , _δpm , _δhm ) in a three-dimensional space, a number of pure substances having known HPS values are plotted, and the Hansen sphere is specified based on the presence or absence of the solubility of the evaluation sample in the pure substances, and the HSP value of the evaluation sample can be calculated by determining the central value of the Hansen sphere.
When the HSP value of the evaluation sample is calculated by determining the central value of the Hansen ball, the calculation can be performed using computer software Hansen Solubility Parameters in Practice (HSPiP).
The interaction radius _R0, which is the radius of the Hansen sphere, can also be calculated using the above software.

In the fouling inhibitor according to the present invention, the interaction radius R0, which is the radius of a Hansen sphere defined by the Hansen solubility parameter of a pure substance that is soluble in the fouling adhering to a heat exchanger for preheating a feed oil in a petroleum refining process and the Hansen solubility parameter of a pure substance that is _not soluble in the fouling adhering to the preheating heat exchanger, is suitably 5.0 to 15.0 (MPa) ^1/2 , more suitably 5.5 to 14.0 (MPa) ^1/2 , and even more suitably 6.0 to 13.0 (MPa) ^1/2 .
In the fouling inhibitor according to the present invention, when the fouling is fouling adhering to a preheat exchanger for feed oil of a fluid catalytic cracking unit (FCC), the above-mentioned interaction radius _R0 is suitably 5.0 to 10.0 (MPa) ^1/2 , more suitably 5.5 to 9.5 (MPa) ^1/2 , even more suitably 6.0 to 9.0 (MPa) ^1/2 , even more suitably 6.0 to 8.0 (MPa) ^1/2 , and even more suitably 6.5 to 7.5 (MPa) ^1/2 .

A method for determining the central value of the Hansen sphere, that is, the HSP value (δd _m , δp _m , δh _m ), will be described with reference to FIG.
First, the HSP values of 16 pure substances having known HSP values are plotted in a three-dimensional space (coordinate axes being the dispersion term δd _m , the polar term δp _m and the hydrogen bond term δh _m ) as shown in FIG.
At this time, as shown in FIG. 1, for example, a pure substance that is soluble in the evaluation sample is indicated by a circle, and a pure substance that is not soluble in the evaluation sample is indicated by an x.
Next, based on the plotted solubilities of the evaluation samples, the imaginary sphere with the smallest radius (shown as a circle in FIG. 1) is determined as the Hansen sphere S, which includes the pure substances that showed solubility (shown with a circle in FIG. 1) and does not include the pure substances that did not show solubility (shown with a cross in FIG. 1).
The radius of the Hansen sphere S (the minimum radius) is the interaction radius _R0 that dissolves the pure substance shown by the circle in the figure and indicates compatibility, and the central values (δd _m , δp _m , δh _m ) of the obtained Hansen sphere S are the HSP values of the evaluation sample.
The compatibility of the above evaluation sample with the pure substance is shown by the following results: 1 mL of a pure substance having a known HSP value is dissolved in 10 mg of the evaluation sample to be evaluated and stirred and mixed for 10 minutes at a temperature of 25° C. If no precipitate remains, it is judged as "soluble (evaluated as ○ in FIG. 1)" and if a precipitate remains, it is judged as "insoluble (evaluated as × in FIG. 1)."
The HSP values and _R0 of mixtures such as fouling components in a heat exchanger for preheating feed oil, which will be described later, and pure substances such as specific fouling inhibitors, which will also be described later, can also be determined by using them as the evaluation samples.

The fouling inhibitor according to the present invention has an interaction radius R 0 , which is the radius of a Hansen _sphere defined by the Hansen solubility parameters of a pure substance that is soluble in the fouling adhering to the preheating heat exchanger and a pure substance that is not soluble in the fouling adhering to the preheating heat exchanger, and
The preheating heat exchanger is made of an aromatic compound having a Hansen solubility parameter distance Ra ratio (Ra/R ₀ ) of 1.0 or less with respect to the contaminants adhering to the preheating heat exchanger.

The Hansen solubility parameter distance Ra corresponds to the distance between the HSP value of the dirt inhibitor to be evaluated and the HSP value of the dirt adhering to the preheating heat exchanger in the Hansen solubility parameter space defined by plotting the Hansen solubility parameters in a three-dimensional space.
FIG. 2 is a conceptual diagram showing the relationship between the HSP value of the contaminants adhering to the preheating heat exchanger, the HSP value of the raw oil base material, and the Hansen solubility parameter distance Ra in the Hansen solubility parameter space (coordinate axes are the dispersion term δd, the polar term δp, and the hydrogen bond term δh).

As shown in FIG. 2, the HSP values (δd _x , δp _x , δh _x ) of the contaminants adhering to a heat exchanger for preheating feed oil in an oil refining process and the HSP values (δd _m , δp _m , δh _m ) of the fouling inhibitor to be evaluated are calculated using the method described above.
The HSP value of the dirt adhering to the preheating heat exchanger may be calculated, for example, by carrying out an evaluation test in which dirt adhering to the inner wall of the preheating exchanger to be used is sampled and dissolved in a pure substance having the above-mentioned known HSP value. The HSP value of the dirt inhibitor to be evaluated may also be calculated by carrying out a similar evaluation test, or if the HSP value of the substance is known, the value may be used as is.
When each of the obtained HSP values is plotted in the Hansen solubility parameter space, the relationship with the Hansen solubility parameter distance Ra, which corresponds to the distance between the two, is expressed by the following formula: Ra ² = 4 × (δd _x - δd _m ) ² + (δp _x - δp _m ) ² + (δh _x - δh _m ) ²
(In the formula, Ra is the distance (Hansen solubility parameter distance) between the HSP value of the dirt adhering to the preheating heat exchanger and the HSP value of the dirt inhibitor to be evaluated in the Hansen solubility parameter space,
δd _x is the variance term of the Hansen solubility parameter of the above-mentioned dirt,
δp _x is the polar term of the Hansen solubility parameter of the above-mentioned dirt,
_δhx is the hydrogen bond term of the Hansen solubility parameter of the above dirt,
δd _m is the variance term of the Hansen solubility parameter of the stain inhibitor to be evaluated;
δp _m is the polar term of the Hansen solubility parameter of the stain inhibitor to be evaluated;
_δhm is the hydrogen bond term of the Hansen solubility parameter of the stain inhibitor to be evaluated.
The Hansen solubility parameter distance Ra can be calculated by substituting the HSP values δd _x , δp _x , and δh _x of the dirt adhering to the preheating heat exchanger and the HSP values δd _m , δp _m , and δh _m of the dirt inhibitor to be evaluated into the above formula.

The fouling inhibitor according to the present invention suitably has a Hansen solubility parameter distance Ra from fouling components adhering to a heat exchanger for preheating raw oil in a petroleum refining process of 0.0 to 10.0 (MPa) ^1/2 , more suitably 0.0 to 9.0 (MPa) ^1/2 , even more suitably 0.0 to 8.0 (MPa) ^1/2 , and even more suitably 0.0 to 7.5 (MPa) ^1/2 .

The fouling inhibitor according to the present invention has an interaction radius R 0 , which is the radius of a Hansen _sphere defined by the Hansen solubility parameters of a pure substance that is soluble in the fouling adhering to the preheating heat exchanger and a pure substance that is not soluble in the fouling adhering to the preheating heat exchanger, and
The ratio (Ra/R ₀ ) of the Hansen solubility parameter distance Ra to the dirt adhering to the preheating heat exchanger is 1.0 or less, preferably 0.9 or less, and more preferably 0.8 or less.
There is no particular lower limit for the ratio (Ra/R ₀ ), and the ratio (Ra/R ₀ ) usually has a value of 0.0 or more.
By making the ratio Ra/ _R0 1.0 or less, it is possible to provide a fouling inhibitor that can sufficiently inhibit adhesion of fouling to the preheating system heat exchanger.

The stain inhibitor according to the present invention comprises an aromatic compound having the ratio Ra/ _R0 of 1.0 or less and a boiling point of 200° C. or higher.
The stain inhibitor according to the present invention is preferably made of an aromatic compound having a boiling point of 210° C. or higher, and more preferably made of an aromatic compound having a boiling point of 220° C. or higher.
Since the boiling point of the fouling inhibitor is 200°C or higher, even when added to raw oil for an oil refining process, it is unlikely to volatilize during refining, and therefore the adhesion of fouling to the heat exchanger for preheating the raw oil can be sufficiently suppressed.

The stain inhibitor of the present invention is preferably composed of an aromatic compound having a melting point of 80°C or less, more preferably composed of an aromatic compound having a melting point of 70°C or less, and even more preferably composed of an aromatic compound having a melting point of 60°C or less.
Since the fouling inhibitor has a melting point of 80° C. or lower, even when added to a feedstock oil for a petroleum refining process, it is easily dissolved and can be easily supplied and distributed during the petroleum refining process.

The purity of the stain inhibitor according to the present invention is preferably 90% or more, more preferably 95% or more, and even more preferably 97% or more.
By ensuring that the purity of the fouling inhibitor is 90% or more, the fouling inhibitor can effectively exert its fouling-inhibiting effect when added to feedstock oil for petroleum refining processes.

The stain inhibitor of the present invention can be selected from any of those having the above-mentioned properties, and specifically includes one or more aromatic compounds represented by the following general formulas (I) to (VI).

That is, the stain inhibitor according to the present invention is a compound represented by the following general formula (I):

(wherein R ¹ is a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms, R ² and R ³ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms and may be the same or different, and the total number of carbon atoms of R ¹ , R ² and R ³ is 0 to 15.)
Examples of the compound include compounds represented by the following formula:

In the compound represented by formula (I), when R ¹ is a hydrocarbon group, R ¹ has 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms.
When R ¹ is a hydrocarbon group, R ¹ may be a straight-chain hydrocarbon group or a branched-chain hydrocarbon group.

Specific examples of ^R1 include a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group.

In the compound represented by formula (I), R ² and R ³ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and may be the same or different.
When ^R2 or ^R3 is a hydrocarbon group, it has 1 to 10 carbon atoms, preferably 1 to 7 carbon atoms, and more preferably 1 to 5 carbon atoms.
When ^R2 or ^R3 is a hydrocarbon group, it may be a linear hydrocarbon group or a branched hydrocarbon group.

When ^R2 or ^R3 is a hydrocarbon group, specific examples include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

The total number of carbon atoms in R ¹ , R ² and R ³ is 0 to 15, preferably 0 to 10, and more preferably 0 to 5.

Specific examples of the compound represented by formula (I) include the following compounds (1) to (5).
(1) In the general formula (I), R ¹ , R ² and R ³ are all hydrogen atoms (Ra/R ₀ is 0.4 when the interaction radius R ⁰ of the contaminants adhering to a heat exchanger for preheating raw oil in a petroleum refining process is 7.1 (MPa) ^1/2 ).
(2) In the general formula (I), R ¹ is a -CH ₃ group, and R ² and R ³ are both hydrogen atoms (when the interaction radius R ⁰ of the contaminants adhering to a heat exchanger for preheating raw oil in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.4).
(3) In the general formula (I), R ¹ is a -(CH ₂ ) ₄ CH ₃ group and R ² and R ³ are both hydrogen atoms (when the interaction radius R ⁰ of the contaminants adhering to a heat exchanger for preheating raw oil in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.6).
(4) In the general formula (I), R ¹ is a -(CH ₂ ) ₉ CH ₃ group and R ² and R ³ are both hydrogen atoms (when the interaction radius R ⁰ of the contaminants adhering to a heat exchanger for preheating raw oil in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.8).
(5) In the general formula (I), R ¹ is a -(CH ₂ ) ₁₄ CH ₃ group and R ² and R ³ are both hydrogen atoms (when the interaction radius R ⁰ of the contaminants adhering to a heat exchanger for preheating raw oil in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.9).

The stain inhibitor according to the present invention is preferably a compound represented by the following general formula (II):

(Note that R ⁴ and R ⁵ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms, and may be the same or different, and the total number of carbon atoms in R ⁴ and R ⁵ is 0 to 10.)
Examples of the compound include compounds represented by the following formula:

In the compound represented by formula (II), R ⁴ and R ⁵ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms, and may be the same or different.
In the compound represented by general formula (II), when ^R4 or ^R5 is a hydrocarbon group, the number of carbon atoms in ^R4 or ^R5 is 1 to 10, preferably 1 to 7, and more preferably 1 to 5.
When R ⁴ or R ⁵ is a hydrocarbon group, R ⁴ or R ⁵ may be a linear hydrocarbon group or a branched hydrocarbon group.

Specific examples of ^R4 and ^R5 include a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group.

The total number of carbon atoms in R ⁴ and R ⁵ is 0 to 10, preferably 0 to 7, and more preferably 0 to 5.

Specific examples of the compound represented by the general formula (II) include the following compounds (1) to (4).
(1) In the general formula (II), R ⁴ and R ⁵ are both hydrogen atoms (when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.4).
(2) In the general formula (II), ^R4 is a hydrogen atom and ^R5 is a _-CH3 group (for example, 2-methylbenzophenone can be mentioned, and when the interaction radius ^R0 of the contaminants adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/ _R0 is 0.5).
(3) In the general formula (II), R ⁴ is a hydrogen atom and R ⁵ is a -(CH ₂ ) ₄ CH ₃ group (when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.6).
(4) In the general formula (II), R ⁴ is a hydrogen atom and R ⁵ is a -(CH ₂ ) ₉ CH ₃ group (when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.8).

The stain inhibitor according to the present invention is preferably a compound represented by the following general formula (III):

(Note that R ⁶ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, R ⁷ and R ⁸ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms and may be the same or different, and the total number of carbon atoms of R ⁶ , R ⁷ and R ⁸ is 0 to 10.)
Examples of the compound include compounds represented by the following formula:

In the compound represented by formula (III), when R ⁶ is a hydrocarbon group, R ⁶ has 1 to 10 carbon atoms, preferably 1 to 7 carbon atoms, and more preferably 1 to 5 carbon atoms.
When R ⁶ is a hydrocarbon group, R ⁶ may be a straight-chain hydrocarbon group or a branched-chain hydrocarbon group.

Specific examples of ^R6 include a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group.

In the compound represented by formula (III), R ⁷ and R ⁸ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms and may be the same or different.
When R ⁷ or R ⁸ is a hydrocarbon group, it has 1 to 10 carbon atoms, preferably 1 to 7 carbon atoms, and more preferably 1 to 5 carbon atoms.
When ^R7 or ^R8 is a hydrocarbon group, it may be a linear hydrocarbon group or a branched hydrocarbon group.

When ^R7 or ^R8 is a hydrocarbon group, specific examples include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

The total number of carbon atoms in R ⁶ , R ⁷ and R ⁸ is 0-10, preferably 0-7, and more preferably 0-5.

Specific examples of the compound represented by formula (III) include the following compounds (1) to (6).
(1) N-methyldiphenylamine in which R ⁶ is a -CH ₃ group and R ⁷ and R ⁸ are both hydrogen atoms in the general formula (III) (when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.8).
(2) In the general formula (III), R ⁶ is a -CH ₃ group, R ⁷ is a hydrogen atom, and R ⁸ is a -(CH ₂ ) ₄ CH ₃ group (when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.9).
(3) In the general formula (III), R ⁶ is a -CH ₃ group, R ⁷ is a hydrogen atom, and R ⁸ is a -(CH ₂ ) ₉ CH ₃ group (when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 1.0).
(4) Diphenylamine in which R ⁶ , R ⁷ and R ⁸ in the general formula (III) are all hydrogen atoms (Ra/R ₀ is 1.0 when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 ).
(5) In the general formula (III), R ⁶ is a -(CH ₂ ) ₄ CH ₃ group, and R ⁷ and R ⁸ are both hydrogen atoms (when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.9).
(6) In the general formula (III), R ⁶ is a -(CH ₂ ) ₉ CH ₃ group, and R ⁷ and R ⁸ are both hydrogen atoms (when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 1.0).

The stain inhibitor according to the present invention is preferably a compound represented by the following general formula (IV):

(Note that R ⁹ and R ¹⁰ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms, and may be the same or different, and the total number of carbon atoms in R ⁹ and R ¹⁰ is 0 to 10.)
Examples of the compound include compounds represented by the following formula:

In the compound represented by formula (IV), R ⁹ and R ¹⁰ are each a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and may be the same or different.
In the compound represented by general formula (IV), when R ⁹ or R ¹⁰ is a hydrocarbon group, R ⁹ or R ¹⁰ has 1 to 10 carbon atoms, preferably 1 to 7 carbon atoms, and more preferably 1 to 5 carbon atoms.
When R ⁹ or R ¹⁰ is a hydrocarbon group, R ⁹ or R ¹⁰ may be a straight-chain hydrocarbon group or a branched-chain hydrocarbon group.

Specific examples of R ⁹ and R ¹⁰ include a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, and an isopentyl group.

The total number of carbon atoms in R ⁹ and R ¹⁰ is 0 to 10, preferably 0 to 7, and more preferably 0 to 5.

Specific examples of the compound represented by formula (IV) include the following compounds (1) to (5).
(1) In the general formula (IV), R ⁹ is a hydrogen atom and R ¹⁰ is a -CH ₃ group (when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.9).
(2) 4-tert-butyldiphenyl sulfide in which R ⁹ is a hydrogen atom and R ¹⁰ is a tert-butyl group in the general formula (IV) (when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.9).
(3) In the general formula (IV), R ⁹ is a hydrogen atom and R ¹⁰ is a -(CH ₂ ) ₄ CH ₃ group (when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.9).
(4) 4-tert-octyldiphenyl sulfide in which R ⁹ is a hydrogen atom and R ¹⁰ is a —C(C ₂ H ₅ ) ₃ group in the general formula (IV) (when the interaction radius R ⁰ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.9).
(5) In the general formula (IV), R ⁴ is a hydrogen atom and R ⁵ is a -(CH ₂ ) ₉ CH ₃ group (when the interaction radius R ⁰ of the dirt adhering to the preheating heat exchanger in the petroleum satellite process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 1.0).

The stain inhibitor according to the present invention is preferably a compound represented by the following general formula (V):

(Note that R ¹¹ is a hydrocarbon group having 1 to 10 carbon atoms, R ¹² and R ¹³ are hydrogen atoms or hydrocarbon groups having 1 to 5 carbon atoms and may be the same or different, and the total number of carbon atoms of R ¹² and R ¹³ is 0 to 5.)
Examples of the compound include compounds represented by the following formula:

In the compound represented by formula (V), R ¹¹ has 1 to 10 carbon atoms, preferably 1 to 7 carbon atoms, and more preferably 1 to 5 carbon atoms.
R ¹¹ may be a straight-chain hydrocarbon group or a branched-chain hydrocarbon group.

Specific examples of R ¹¹ include a methylene group.

In the compound represented by formula (I), R ¹² and R ¹³ are a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and may be the same or different.
When R ¹² or R ¹³ is a hydrocarbon group, the carbon number thereof is 1 to 10.
It is preferably 1 to 7, and more preferably 1 to 5.
When R ¹² or R ¹³ is a hydrocarbon group, it may be a straight-chain hydrocarbon group or a branched-chain hydrocarbon group.

When R ¹² or R ¹³ is a hydrocarbon group, specific examples include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

The total number of carbon atoms in R ¹² and R ¹³ is 0 to 10, preferably 0 to 7, and more preferably 0 to 5.

Specific examples of the compound represented by formula (V) include the following compounds (1) to (4).
(1) 2-benzylpyridine in which, in the general formula (V), R ¹¹ is a —CH ₂ — group and R ¹² and R ¹³ are both hydrogen atoms (Ra/R ₀ is 0.7 when the interaction radius R ₀ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 ).
(2) In the general formula (V), R ¹¹ is a -CH ₂ - group, R ¹² is a hydrogen atom, and R ¹³ is a -(CH ₂ ) ₄ CH ₃ group (when the interaction radius R ₀ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.8).
(3) In the general formula (V), R ¹¹ is a -CH ₂ - group, R ¹² is a hydrogen atom, and R ¹³ is a -(CH ₂ ) ₉ CH ₃ group (when the interaction radius R ₀ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.9).
(4) In the general formula (V), R ¹¹ is a -CH ₂ - group, R ¹² is a -C ₃ H ₇ group, and R ¹³ is a -C ₇ H ₁₅ group (when the interaction radius R ₀ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.9).

The stain inhibitor according to the present invention is preferably a compound represented by the following general formula (VI):

(Note that R ¹⁴ to R ²⁰ are hydrogen atoms or hydrocarbon groups having 1 to 3 carbon atoms, and may be the same or different, and the total number of carbon atoms of R ¹⁴ to R ²⁰ is 0 to 10.)
Examples of the compound include compounds represented by the following formula:

In the compound represented by formula (VI), when any of R ¹⁴ to R ²⁰ is a hydrocarbon group, it has 1 to 3 carbon atoms, and preferably 1 or 2 carbon atoms.
When any of R ¹⁴ to R ²⁰ is a hydrocarbon group, it may be a straight-chain hydrocarbon group or a branched-chain hydrocarbon group.

When any of R ¹⁴ to R ²⁰ is a hydrocarbon group, specific examples include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

The total number of carbon atoms of R ¹⁴ to R ²⁰ is 0 to 10, preferably 0 to 7, and more preferably 0 to 5.

Specific examples of the compound represented by the general formula (VI) include the following compounds (1) to (5).
(1) In the general formula (VI), R ¹⁴ to R ²⁰ are all hydrogen atoms (Ra/R ₀ is 0.7 when the interaction radius R ₀ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 ).
(2) In the general formula (VI), any one of R ¹⁴ to R ¹⁷ is a -C ₅ H ₁₁ group and the other groups are all hydrogen atoms, and R ¹⁸ to R ²⁰ are all hydrogen atoms (when the interaction radius R ₀ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.8).
(3) In the general formula (VI), any one of R ¹⁴ to R ¹⁷ is a -C ₁₀ H ₂₁ group and the other groups are all hydrogen atoms, and R ¹⁸ to R ²⁰ are all hydrogen atoms (when the interaction radius R ₀ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.9).
(4) In the general formula (VI), R ¹⁴ to R ¹⁹ are all hydrogen atoms and R ²⁰ is a —C ₅ H ₁₁ group (when the interaction radius R ₀ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.8).
(5) In the general formula (VI), R ¹⁴ to R ¹⁹ are all hydrogen atoms and R ²⁰ is a —C ₁₀ H ₂₁ group (when the interaction radius R ₀ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.9).
(6) 2,3,3,5-tetramethyl-3H-indole in which R ¹⁵ , R ¹⁹ , R ¹⁸ and R ²⁰ are all methyl groups, and R ¹⁴ , R ¹⁶ and R ¹⁷ are all hydrogen atoms in the general formula (VI) (when the interaction radius R ₀ of the dirt adhering to a preheating heat exchanger in a petroleum refining process is 7.1 (MPa) ^1/2 , Ra/R ₀ is 0.8).

Examples of usage modes of the fouling inhibitor of the present invention include blending it into a coating liquid as a fouling inhibitor when the operation of a crude oil preheating heat exchanger to which the agent is applied is stopped and the inside is cleaned, and blending raw oil blended with the fouling inhibitor of the present invention into the preheating heat exchanger to which the agent is applied and distributing it. Either of these modes can inhibit the adhesion of fouling to the walls of the heat exchanger, or can suitably dissolve fouling that has already adhered.
Among the usage modes of the fouling inhibitor of the present invention, a preferred mode is one in which the fouling inhibitor of the present invention is mixed with raw oil and supplied to the preheating heat exchanger to which it is applied and distributed, since the fouling inhibitor can exert its heat exchanger fouling inhibitor effect while the preheating heat exchanger is continuously operated.

When raw oil containing the fouling inhibitor of the present invention is supplied to a preheating heat exchanger to which the agent is applied, the concentration of the fouling inhibitor of the present invention in the raw oil is preferably 100 to 5000 ppm by mass, more preferably 300 to 4500 ppm by mass, and even more preferably 500 to 4000 ppm by mass.
By having the concentration of the fouling inhibitor in the raw oil within the above range, it is possible to suppress the adhesion of fouling from the raw oil to the walls of the preheating heat exchanger, or to suitably dissolve fouling that has already adhered.

According to the present invention, it is possible to provide a fouling inhibitor for a heat exchanger for preheating raw oil in an oil refining process, which exhibits excellent solubility for fouling particles adhering to the heat exchanger for preheating raw oil, and can sufficiently inhibit the adhesion of fouling particles to the heat exchanger for preheating raw oil.

Next, the feedstock oil for the petroleum refining process according to the present invention will be described.
The feedstock oil for a petroleum refining process according to the present invention is characterized in that it comprises a feedstock oil containing 100 ppm by mass to 5000 ppm by mass of the fouling inhibitor according to the present invention.
Details of the stain inhibitor according to the present invention and the raw oil containing the stain inhibitor are as described above.

In the feedstock oil for petroleum refining processes according to the present invention, the blending ratio (concentration) of the fouling inhibitor according to the present invention is 100 to 5000 ppm by mass, preferably 300 to 4500 ppm by mass, and more preferably 500 to 4000 ppm by mass.
By having the blending ratio of the fouling inhibitor in the raw oil of the present invention within the above range, it is possible to suppress the adhesion of fouling particles caused by the raw oil to the walls of the preheating heat exchanger, or to suitably dissolve fouling particles that have already adhered.

The feedstock oil for the petroleum refining process according to the present invention is preferably one in which the temperature difference over time of the feedstock oil temperature at the heater outlet, calculated by the following method, is 0 to 40°C, more preferably 0 to 35°C, and even more preferably 0 to 30°C.

<Method for measuring the temperature difference over time of the feed oil temperature at the heater outlet>
As shown in the schematic cross-sectional view of FIG. 3, 1.1 L of raw oil stored in a raw oil tank T and heated to 70° C. by a hot plate HP is fed at 10 mL per minute into a flow pipe c (diameter 6.5 mm) whose entire flow path is maintained at 70° C. by a ribbon heater (not shown), while being heated sequentially at set temperatures T1 (170° C.) and T2 (300° C.) by heaters HT1 and HT2 each having a heater rod R (made of stainless steel, length 200 mm, diameter 6 mm) disposed in the raw oil flow pipe, and returned to the raw oil tank T. After this operation is continued for 600 minutes, when the heater outlet temperature T3 of the raw oil is measured by a raw oil temperature measuring means TM2out disposed at the raw oil outlet of the heater HT2, the temperature difference calculated by "(heater outlet temperature T3 at the beginning of heating) - (heater outlet temperature T3 after heating for 600 minutes)" is measured twice in the heater HT2, and the arithmetic average value of the temperature difference is defined as the temperature difference ΔT.

Because the temperature difference ΔT is controlled within the above range, i.e., because the heater outlet temperature T3 is maintained within a specified range, it can be determined that the amount of dirt adhering to the heater rod R inside the heating heater HT is small, and that the adhesion of dirt to the raw oil preheating heat exchanger is sufficiently suppressed.
If the temperature difference ΔT is outside the above range, it is not possible to maintain the heater outlet temperature T3, and therefore it can be determined that the amount of dirt adhering to the heater rod R inside the heating heater HT increases, and the adhesion of dirt to the raw oil preheating heat exchanger cannot be sufficiently suppressed.

According to the present invention, it is possible to provide a feedstock oil for an oil refining process that exhibits excellent solubility for contaminants adhering to a heat exchanger for preheating feedstock oil, and can sufficiently suppress the adhesion of contaminants to the heat exchanger for preheating feedstock oil.

Next, a method for suppressing fouling of a feed oil preheating heat exchanger in an oil refining process according to the present invention will be described.
The method for inhibiting fouling of a heat exchanger for preheating a feedstock oil in an oil refining process according to the present invention is characterized in that a feedstock oil containing 100 ppm by mass to 5,000 ppm by mass of the fouling inhibitor according to the present invention is supplied to the heat exchanger for preheating the feedstock oil.
Details of the stain inhibitor according to the present invention and the raw oil containing the stain inhibitor are as described above.
The details of the feed oil preheating heat exchangers for supplying each feed oil are also as described above.

In the method for inhibiting fouling of a heat exchanger for preheating a feed oil in an oil refining process according to the present invention, the blending ratio (concentration) of the fouling inhibitor according to the present invention in the feed oil is 100 to 5000 ppm by mass, preferably 300 to 4500 ppm by mass, and more preferably 500 to 4000 ppm by mass.
In the method for inhibiting fouling of a feedstock oil preheating heat exchanger in an oil refining process according to the present invention, by setting the blending ratio of the fouling inhibitor in the feedstock oil within the above-mentioned range, it is possible to inhibit the adhesion of fouling from the feedstock oil to the walls of the preheating heat exchanger, or to suitably dissolve fouling that has already adhered.

According to the present invention, raw oil containing the fouling inhibitor of the present invention is supplied to the preheating heat exchanger, so that the fouling inhibitor effect of the heat exchanger can be easily exerted while the preheating heat exchanger is continuously operating.
Therefore, according to the present invention, a method for suppressing fouling of a raw oil preheating heat exchanger in an oil refining process can be provided, which exhibits excellent solubility for fouling adhering to the raw oil preheating heat exchanger, and can easily and sufficiently suppress the adhesion of fouling to the raw oil preheating heat exchanger.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

(Examples 1 to 6, Comparative Examples 1 and 2)
(1) Calculation of the interaction radius _R0 Contaminants adhering to the inner wall surface of a heat exchanger for preheating feed oil for a fluid catalytic cracking unit used in an oil refining process were sampled, and 1 ml of each of 16 pure substances having known HSP values was added to 10 mg of the contaminants at a temperature of 25°C. The mixture was stirred and mixed for 10 minutes, and then allowed to stand for 5 minutes, and the solubility was evaluated visually.
Based on the obtained solubility evaluation results, the central value of the Hansen sphere (HSP value) was calculated using computer software Hansen Solubility Parameters in Practice (HSPiP), and _the interaction radius R ₀ was calculated, which was 7.1 (MPa) ^1/2 .
(2) Feedstock Base Stock As base stock A and base stock B constituting the feedstock oil composition for a fluid catalytic cracking unit, desulfurized vacuum gas oil (T-VGO) and directly desulfurized heavy oil (DDS-P), respectively, having the physical properties shown in Table 1, were prepared.
The physical properties shown in Table 1 were measured by the methods described below.

(Distillation properties)
Measurement was performed based on the provisions of JIS K2254:1998.

(Density at 15°C (Density (15°C)))
Measurement was performed based on the provisions of JIS K2249-1:2011.

(flash point)
The measurement was performed based on "Determination of flash point - Part 3: Pensky-Martens closed-cell method" specified in JIS K 2265-3:2007.

(Sulfur content)
The sulfur content of 500 ppm by mass or less was measured based on "Crude oil and petroleum products-Determination of sulfur content-Part 6: Ultraviolet fluorescence method" specified in JIS K 2541-6:2003, and the sulfur content of more than 500 ppm by mass was measured based on "Crude oil and petroleum products-Determination of sulfur content-Part 4: Radiation excitation method" specified in JIS K 2541-4:2003.

(Aromatic content percentage)
Measurement was carried out based on the provisions of JPI-5S-49-97.

(carbon residue)
The measurement was performed based on "Crude petroleum and petroleum products - Determination of carbon residue - Part 2: Micro method" specified in JIS K 2270-2:2009.

(ash)
Measurement was performed based on "Crude petroleum and petroleum products-Determination method for ash content and sulfated ash content" specified in JIS K 2272:1998.

(Nitrogen content)
The measurement was performed based on "Crude oil and petroleum products -- Nitrogen analysis test method" (chemiluminescence method) specified in JIS K 2609:1998.

(Kinematic Viscosity at 50°C (Kinematic Viscosity (50°C))
Measurements were made based on "Crude oil and petroleum products -- Kinematic viscosity test method and viscosity index calculation method" specified in JIS K 2283:2000.

(Pour Point)
Measurement was performed based on "Test method for pour point and cloud point of crude oil and petroleum products" specified in JIS K 2269:1987.

(Asphaltene content)
Measurement was carried out based on the provisions of JPI-5S-22-83.

(3) Selection of Soil Inhibitor As the stain inhibitor used in each of the Examples and Comparative Examples, stain inhibitors exhibiting the physical properties shown in Table 2 were selected.
To 1 ml of each stain inhibitor, 1 ml of each of 16 pure substances with known HSP values was added at 25°C, mixed with stirring for 10 minutes, then allowed to stand for 5 minutes, and the solubility was evaluated visually.
Based on the solubility evaluation results obtained, the Hansen ball median value (HSP value) of each stain inhibitor was determined using computer software Hansen Solubility Parameters in Practice (HSPiP).
From the HSP value of each stain inhibitor and the HSP value of the above-mentioned stain, the Hansen solubility parameter distance Ra between each stain inhibitor and the stain was calculated using computer software Hansen Solubility Parameters in Practice (HSPiP), and then the ratio (Ra/R ₀ ) to the above-mentioned interaction radius R ₀ was calculated.
The results are shown in Table 2.
In Comparative Example 1, no stain inhibitor was used.

(3) Preparation of Feedstock The above-mentioned base material A and base material B were mixed in a volume ratio of base material A:base material B = 7:3 to prepare a base mixture. To the base mixture, fouling inhibitors each having the physical properties shown in Table 2 were added in the blending ratios shown in Table 3 to prepare a feedstock for a fluid catalytic cracking unit.
Next, in the heating device shown in the schematic cross-sectional view of FIG. 3, any of the feedstock oils prepared as described above was stored in a feedstock oil tank T.
1.1 L of raw oil stored in a raw oil tank T and heated to 70° C. by a hot plate HP was fed at 10 mL per minute into a distribution pipe c (diameter 6.5 mm) whose entire flow path was maintained at 70° C. by a ribbon heater (not shown), while being heated sequentially to set temperatures T1 (170° C.) and T2 (300° C.) by heaters HT1 and HT2, each of which had a heater rod R (made of stainless steel, length 200 mm, diameter 6 mm) arranged in the raw oil distribution pipe, and returned to the raw oil tank T. After this operation was continued for 600 minutes, the heater outlet temperature T3 of the raw oil was measured by a raw oil temperature measuring means TM2out arranged at the raw oil outlet of the heater HT2, and the temperature difference calculated by "(heater outlet temperature T3 at the beginning of heating) - (heater outlet temperature T3 after heating for 600 minutes)" was measured twice in the heater HT2, and the arithmetic average value was determined as the temperature difference ΔT.
The results are shown in Table 3.

From Tables 2 and 3, it can be seen that in Examples 1 to 6, an aromatic compound having a boiling point of 200°C or higher and an Ra/ _R0 of 1.0 or less is used as the stain inhibitor, and therefore the feedstock oil containing such a stain inhibitor can control the temperature difference ΔT {(heater outlet temperature T3 at the start of heating) - (heater outlet temperature T3 after heating for 600 minutes)} of the heater outlet temperature in heater HT2 to 16.3 to 38.7°C when heated, and therefore adhesion of stains can be sufficiently suppressed.

On the other hand, from Tables 2 and 3, it can be seen that in Comparative Examples 1 and 2, because the above-mentioned specified stain inhibitors were not used, when the obtained raw oil was heated, the temperature difference ΔT {(heater outlet temperature T3 at the beginning of heating) - (heater outlet temperature T3 after heating for 600 minutes)} at the heater outlet temperature T3 in the heater HT2 was high at 42.7 to 49.5°C, and the adhesion of stains could not be sufficiently suppressed.

According to the present invention, it is possible to provide a fouling inhibitor for a heat exchanger for preheating raw oil in an oil refining process, which exhibits excellent solubility for fouling adhering to the heat exchanger for preheating raw oil, and which can sufficiently inhibit the adhesion of fouling to the heat exchanger for preheating raw oil, a raw oil for the oil refining process, and a method for inhibiting fouling of a heat exchanger for preheating raw oil in an oil refining process.

Claims (4)

A fouling inhibitor for a heat exchanger for preheating raw oil in an oil refining process, comprising:
The feed oil preheating heat exchanger is a feed oil preheating heat exchanger for an atmospheric distillation unit, a feed oil heat exchanger for a vacuum distillation unit, a feed oil preheating heat exchanger for a fluid catalytic cracking unit, a feed oil preheating heat exchanger for a direct desulfurization unit, or a feed oil preheating heat exchanger for an indirect desulfurization unit,
In the Hansen solubility parameter space defined by plotting the Hansen solubility parameters in a three-dimensional space,
The Hansen solubility parameter of a pure substance that is soluble in the contaminants adhering to the heat exchanger for preheating raw oil and the Hansen solubility parameter of a pure substance that is not soluble in the contaminants adhering to the heat exchanger for preheating raw oil are defined as the radius of interaction R ₀ of the Hansen sphere.
The ratio (R _a /R ₀ ) of the Hansen solubility parameter distance R _a to the contaminants adhering to the heat exchanger for preheating the raw oil is 1.0 or less;
It is composed of aromatic compounds having a boiling point of 200°C or higher,
The following general formula (III)

(Note that R ⁶ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, R ⁷ and R ⁸ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms and may be the same or different, and the total number of carbon atoms of R ⁶ , R ⁷ and R ⁸ is 0 to 10.)
and a compound represented by the following general formula (IV):

(Note that R ⁹ and R ¹⁰ are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms, and may be the same or different, and the total number of carbon atoms in R ⁹ and R ¹⁰ is 0 to 10.)
and a compound represented by the following general formula (V):

(Note that R ¹¹ is a hydrocarbon group having 1 to 10 carbon atoms, R ¹² and R ¹³ are hydrogen atoms or hydrocarbon groups having 1 to 5 carbon atoms and may be the same or different, and the total number of carbon atoms of R ¹² and R ¹³ is 0 to 5.)
is one or more compounds selected from the group consisting of
A fouling inhibitor for a heat exchanger for preheating raw oil in an oil refining process. 2. The fouling inhibitor for a feedstock oil preheating heat exchanger in a petroleum refining process according to claim 1, wherein the feedstock oil preheating heat exchanger is a feedstock oil preheating heat exchanger for a fluid catalytic cracking unit. A feedstock oil for a petroleum refining process, comprising a feedstock oil containing 100 ppm by mass to 5000 ppm by mass of the fouling inhibitor according to claim 1 or 2. A method for inhibiting fouling of a heat exchanger for preheating feed oil in an oil refining process, comprising:
A method for inhibiting fouling of a heat exchanger for preheating raw oil in an oil refining process, comprising supplying raw oil containing 100 ppm by mass to 5000 ppm by mass of the fouling inhibitor according to claim 1 or 2 to the heat exchanger for preheating raw oil.

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