JP2005187581A - Low-temperature fluidity improver for fuel oil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a low-temperature fluidity improver which improves low-temperature fluidity of a fuel oil containing a residual oil, namely improves a CFPP (cold filter plugging point) and a corrected cold filter plugging point, is obtained by dispersing wax precipitated under slow cooling into a fuel oil and does not inhibits passage of an fuel oil through a filter and a fuel oil composition containing the improver. <P>SOLUTION: The low-temperature fluidity improver for a fuel oil comprises a specific hydrocarbon (compound A) and an amidation reaction product between an 8-24C hydrocarbon group-containing hydrocarbon-substituted succinic acid (anhydride) and an 8-24C hydrocarbon group-containing mono(di)hydrocarbon-substituted amine and/or its salt (compound B) in the weight ratio of (compound A):(compound B) of 1:99-50:50. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a low-temperature fluidity improver for fuel oil and a fuel oil composition to which the low-temperature fluidity improver is added. More specifically, the present invention relates to a low-temperature fluidity improver for fuel oil containing residual oil, and improves low-temperature fluidity. Therefore, the present invention relates to a fuel oil composition excellent in low-temperature oil permeability and / or wax dispersibility to which the low-temperature fluidity improver is added.

Middle distillates obtained by distilling crude oil include kerosene, light oil, and heavy oil A, and are used in large quantities as fuel oil. Among these, light oil and heavy oil A solidify the paraffin wax contained at low temperatures, clogging the filter in the fuel system, or blocking the piping, making it impossible to start the engine and combustion equipment. May stop and cause serious problems.

Above all, for A heavy oil used as fuel oil for hot water heating boilers, greenhouse hot air heaters, diesel generators for private generators, marine diesel engines such as fishing boats, etc., oil supply pipes to boilers and engines Many blockages, fuel filter blockages, etc. have occurred, and it is desired to improve the fluidity of A heavy oil at low temperatures. Especially for medium to heavy distillate fuel oils such as A heavy oil containing atmospheric distillation residue and / or vacuum distillation residue to give residual carbon content, troubles have occurred under actual use conditions. However, there is a strong demand for improvement in this regard as well.

As a method for testing the low-temperature performance of fuel oil, a test method called a cold filter plugging point (hereinafter referred to as CFPP) is generally used. This test is a method of evaluating the clogging property of the filter by rapidly cooling the sample oil and passing it through a filter having an opening of 45 μm every time the temperature drops by 1 ° C.

This CFPP test is a test method developed mainly for diesel oil, and when applied to medium to heavy distillate fuel oil such as A heavy oil, there is an example that CFPP does not show the low temperature limit temperature. I know. This is because the cooling rate of the sample oil in the CFPP test is rapid cooling (about 40 ° C./hour), and the cooling rate of the temperature of the fuel oil in the fuel oil tank under actual use conditions (about 1-2 ° C./hour). It is thought that the reason is that it is far from the time. In general, when the cooling rate is high, the precipitated wax crystals become small and easily pass through the filter. On the other hand, if the cooling rate is low, the precipitated wax crystals become large, and filter clogging is likely to occur.

That is, it is considered that heavy distillate fuel oil such as A heavy oil managed in the CFPP test has a possibility of causing clogging of the filter at a temperature higher than the low temperature operating limit temperature. Further, when a low temperature fluidity improver for fuel oil generally used for heavy distillate fuel oil such as A heavy oil containing residual carbon is added, asphaltene contained in residual carbon and one of the low temperature fluidity improvers The parts may affect each other, forming a large wax and causing the filter to become clogged.

As described above, when applied to heavy distillate fuel oil such as A heavy oil containing residual carbon, the cooling rate is too large in the CFPP test for light oil, and the crystals become small and are included in the residual carbon. Asphaltenes and cold flow improvers may affect the wax and may not exhibit a cold operating limit temperature. In other words, it is problematic to manage heavy distillate fuel oil such as A heavy oil containing residual carbon only in the CFPP test.

Therefore, in order to estimate the actual low-temperature operating limit temperature, a simple test method was examined by the Japan Petroleum Institute Fuel Oil Division A Heavy Oil Technical Committee. As a result, the modified clogging point test highly correlated with the actual operating temperature limit [Petroleum product debate (November 10 and 11, 1994) "Examination of low temperature fluidity evaluation method for heavy oil A" Preprint Of the correction methods described in Table 3 on page 44 <Correlation between various corrected clogging points and oil passage limit temperature>, “corrected 4 clogging points” having the best correlation coefficient with the oil passage limit temperature were established. In this test, the fuel oil was cooled in a cooling tank at a cooling rate of 1 ° C./hour, and each time the temperature of the cooling tank decreased by 1 ° C., the fuel oil was clogged by passing it through a filter with a mesh size of 149 μm. It is to evaluate.

Furthermore, the performance desired for the fuel oil includes filter oil permeability. It is said that filter oil permeability is often deteriorated by adding an additive having poor solubility to fuel oil. Further, in order to impart residual carbon to the fuel oil, the residual oil may be included in the fuel oil. However, the fuel oil with a high content of the residual oil often deteriorates the filter oil permeability. Fuel oil with poor filter oil permeability causes troubles such as clogging the fuel system filter at a temperature higher than the cloud point (hereinafter referred to as CP) of the fuel oil and stopping the supply of fuel oil. Sometimes.

As a general test method for filter oil permeability, the fuel oil is cooled to a temperature 5 to 10 ° C. higher than the CP of the fuel oil, and filtered using a filter having an appropriate opening (5 μm to 10 μm) at that temperature. By testing. More specifically, there are a method of measuring the differential pressure before and after the filter with a constant oil flow rate using a metering pump, a method of measuring the oil flow rate or speed of the filter with a constant filtration pressure, etc. It is used.

Further, the performance desired for the fuel oil includes wax dispersibility under slow cooling and low temperature. This is because when the fuel oil is transported by a tanker or when the fuel oil is stored in the tank, the outside air temperature drops, and when the fuel temperature falls below the CP, wax is deposited, and the deposited wax settles at the bottom of the tank. Problems such as forming a dense wax layer. In particular, many fuel tanks in combustion facilities are designed to supply fuel from the bottom of the fuel tank so that as much fuel as possible can be used. When wax settles, fuel with a high wax concentration is supplied from the bottom of the tank. It is said that troubles such as blockage of the fuel filter are likely to occur.

As a general test method for wax dispersibility, a certain amount of fuel oil is collected in a graduated graduated cylinder, etc., from a temperature about 5 ° C. higher than the CP of the fuel oil to near the low temperature operating limit temperature of the fuel oil. A method of cooling at a cooling rate of 1 ° C./hour and measuring the sedimentation ratio of the precipitated wax is used.

Conventionally, various methods are used as a method for maintaining the fluidity of fuel oil at a low temperature. For example, in order to prevent the temperature of the fuel oil from being lowered even at a low temperature, there is a method in which the fuel oil is directly heated and kept warm with hot water or a heater, but this is not an advantageous method in terms of energy cost. A method is also used in which kerosene, which is fluid even at relatively low temperatures, is added to light oil / heavy oil A to reduce wax precipitation and maintain fluidity at low temperatures, but there is much demand in the winter when the temperature drops. It is difficult to say that it is an advantageous method because the price is high.

Furthermore, as a technique for improving the fluidity of fuel oil at low temperatures, a method of adding a low temperature fluidity improver to the fuel is known. The low temperature fluidity improver acts on the wax precipitated from the fuel at a low temperature, and has the function of stabilizing the precipitated wax in the fuel oil while being fine. Examples of fluidity improvers proposed so far include polymer types composed of ethylenic monomers such as ethylene-propylene copolymers (Patent Documents 1 and 2) and ethylene-vinyl acetate copolymers (Patent Document 3). Additive, combination of aromatic dicarboxylic acid amide / amine salt and ethylene-vinyl acetate copolymer or ethylene-propylene copolymer (Patent Document 4, Patent Document 5), combination of aromatic dicarboxylic acid amide / amine salt and polyester compound ( Patent Document 6) has been proposed. However, these additives may be effective in the CFPP test, but have little effect on the corrected clogging point test and precipitated wax dispersibility, and often deteriorate the oil permeability of the filter. For example, when ethylene-vinyl acetate copolymer is used for the fuel oil, the oil passage performance starts to deteriorate at an addition amount of 300 mg / L. When the addition amount exceeds 500 mg / L, the filter oil passage performance becomes a serious problem in practice. There is also.

Furthermore, in order to suppress sedimentation of wax precipitated at low temperature, surfactant type additives such as alkenyl succinic acid amide (Patent Document 7) and polyoxyalkylene ester (Patent Document 8) and polyalkylene polyamine-α, ω -Combinations of amide esters by reaction of alkylene oxide adducts of bis-fatty acid amides with fatty acids and ethylene-vinyl acetate copolymers or alkyl (meth) acrylates (Patent Document 9) have been proposed. Little effect on clogging points.
Shoko 60-35396 JP-A-60-137997 JP 55-137193 A JP 56-92996 JP 58-1792 A JP-A-6-49464 JP 56-43391 JP-A-57-177092 JP 7-47742

The present invention improves the low temperature fluidity, that is, CFPP and the correction clogging point with respect to the above-described technical problems, that is, the fuel oil containing the residual oil, and disperses the wax precipitated under slow cooling in the fuel oil, An object of the present invention is to provide a low-temperature fluidity improver that does not impair the filter oil permeability of a fuel oil and a fuel oil composition containing the same.

The inventors of the present invention have made extensive studies to achieve the above object. As a result, by adding specific hydrocarbons and specific amidation reaction products to fuel oil containing residual oil, wax precipitated under slow cooling is dispersed, and low-temperature flow without deteriorating filter oil permeability I found the fact that it can improve the sex.

（式中、ｎは２以上の整数を、Ｘ^１〜Ｘ^８はそれぞれ独立して、水素、直鎖炭化水素基又は分岐炭化水素基、もしくは炭素数３以上のシクロ炭化水素基を示す。）

（式中、Ｘ^９、Ｘ^１０のうちいずれか一方は炭素数８乃至２４の直鎖又は分岐の炭化水素基で、もう一方は水素を示す。Ｘ^１1はＮＲ¹Ｒ²又はＮＨＲ^３、Ｘ^１2はＨ^＋、ＨＮ^＋ＨＲ^４Ｒ^５又はＨＮ^＋Ｈ₂Ｒ^６である。また、Ｒ^１〜Ｒ^６はそれぞれ独立して炭素数８乃至２４の炭化水素基を示す。） That is, in the present invention, the weight ratio of the compound A represented by the following general formula (1) and the compound B represented by the following general formula (2) (compound A) :( compound B) is 1:99 to 50: It is a low-temperature fluidity improver for fuel oil that is contained in a range of 50.

(In the formula, n represents an integer of 2 or more, and X ^{1 to} X ⁸ each independently represent hydrogen, a linear hydrocarbon group or a branched hydrocarbon group, or a cyclohydrocarbon group having 3 or more carbon atoms.)

(In the formula, any one of X ⁹ and X ¹⁰ is a linear or branched hydrocarbon group having 8 to 24 carbon atoms, and the other represents hydrogen. X ¹¹ is NR ¹ R ² or NHR ³ , X ¹² is H ⁺ , HN ⁺ HR ⁴ R ^5, or HN ⁺ H ₂ R ⁶ , and R ^{1 to} R ⁶ each independently represents a hydrocarbon group having 8 to 24 carbon atoms.

The present invention further relates to a fuel oil containing the above-described fluidity improver for fuel oil. That is, the above-mentioned fluidity improver for fuel oil is contained in an amount of 10 mg / L to 2000 mg / L, and the wax crystals that precipitate when cooled to a temperature lower than CP under slow cooling conditions are reduced, and the dispersibility of the wax is improved. A fuel oil composition having improved low-temperature fluidity without deteriorating filter oil permeability of fuel oil at higher temperatures.

By adding the low-temperature fluidity improver of the present invention to fuel oil containing residual oil, the corrected clogging point and CFPP are improved without impairing the filter oil permeability, and further the dispersibility of the precipitated wax is improved. doing. Thereby, when using the fuel oil containing the residual oil, or when transporting or storing, it is possible to solve various problems such as filter clogging and harmful effects due to wax sedimentation.

The fuel oil targeted by the present invention is a so-called medium to heavy distillate fuel oil having a boiling point range of 150 to 500 ° C. containing a residual oil for imparting a residual carbon content. More specifically, for example, residual oil obtained by distilling petroleum at normal pressure or reduced pressure, residual oil obtained by hydrodesulfurization or catalytic reforming, thermal cracking, catalytic cracking, hydrogen It is a distillation residue oil of cracked oil such as chemical cracking, and is generally characterized by containing asphaltenes. Medium to heavy distillate fuel oil obtained by directly distilling petroleum oil at normal pressure or reduced pressure, medium to heavy distillate fuel oil subjected to hydrodesulfurization or catalytic reforming, thermal cracking, catalyst It is a fuel oil contained in one or a mixture of two or more kinds of medium to heavy distillate fuel oil that has undergone cracking treatment such as cracking and hydrocracking.

Examples of the compound represented by the general formula (1) according to the present invention include normal paraffin, isoparaffin, cycloparaffin, a mixture of microcrystalline wax, polyethylene, polypropylene, a copolymer of ethylene and propylene, polybutene, polyisobutene, and the like. These mixtures are mentioned. Further, the compound represented by the general formula (1) preferably has 20 to 100 carbon atoms. Further, the compound represented by the general formula (1) is selected from normal paraffin, isoparaffin, cycloparaffin, and microcrystalline wax. More preferred are seeds or two or more compounds.

Examples of the compound represented by the general formula (2) include the following (2) -1 to (2) -7.
(2) -1: Amidation reaction product of a hydrocarbon-substituted succinic acid (anhydride) having 8 to 24 carbon atoms in the hydrocarbon group and a monohydrocarbon-substituted amine having 8 to 24 carbon atoms in the hydrocarbon group (2) -2: Amidation reaction product of a hydrocarbon-substituted succinic acid (anhydride) having 8 to 24 carbon atoms in the hydrocarbon group and a dihydrocarbon-substituted amine having 8 to 24 carbon atoms in the hydrocarbon group (2) -3; salt of compound (2) -1 and monohydrocarbon-substituted amine having 8 to 24 carbon atoms of hydrocarbon group (2) -4; compound of (2) -1 and hydrocarbon group A salt of a dihydrocarbon-substituted amine having 8 to 24 carbon atoms (2) -5; a salt of a compound of (2) -2 with a monohydrocarbon-substituted amine having a hydrocarbon group having 8 to 24 carbon atoms ( 2) -6; a compound of (2) -2 and a dihydrocarbon-substituted amine having 8 to 24 carbon atoms in the hydrocarbon group; Salt (2) -7; mixture of the (2) -1 (2) -6 of compound

In this case, the hydrocarbon-substituted succinic acid (anhydride) having 8 to 24 carbon atoms in the hydrocarbon group is, for example, an alkyl succinic acid (anhydride) or alkenyl succinic acid having 8 to 24 carbon atoms in the alkyl group or alkenyl group. There is an acid (anhydride), and the alkyl group or alkenyl group may be linear or branched. At this time, the alkyl succinic acid or the alkenyl succinic acid may be one kind or a mixture of two or more kinds.

Examples of the mono (or di) hydrocarbon-substituted amine having 8 to 24 carbon atoms in the hydrocarbon group include, for example, mono (or di) alkyl (or alkenyl) amines having 8 to 24 carbon atoms in the alkyl group or alkenyl group. The alkyl group or alkenyl group can be either linear or branched. At this time, the mono (or di) alkyl (or alkenyl) amine may be one kind or a mixture of two or more kinds.

Any of the compounds represented by the general formula (2) can be obtained by a known method. The reaction molar ratio represented by (hydrocarbon-substituted succinic acid (anhydride)) :( hydrocarbon-substituted amine) is preferably larger than the molar ratio of hydrocarbon-substituted amine. If the molar ratio of the hydrocarbon-substituted amine is smaller than 1: 1, dibasic acid of succinic acid (anhydride) remains, which may adversely affect fuel oil and lubricating oil.
The reaction between the hydrocarbon-substituted succinic acid (anhydride) and the hydrocarbon-substituted amine is an exothermic reaction. Also, the larger the number of carbon atoms in the hydrocarbon-substituted amine, the higher the melting point of the hydrocarbon-substituted amine. Thus, a reaction solvent may be used. However, it is desirable that the reaction solvent used has no active group such as a hydroxyl group, a carboxyl group, an acid anhydride group, and an amino group.

  The fluidity improver of the present invention is preferably added in an amount of 10 mg / L to 2000 mg / L to the fuel oil containing the residual oil in order to obtain good performance. At this time, Compound A and Compound B may be added simultaneously or separately. Further, the fluidity improver of the present invention may contain other components as long as the object of the present invention is not impaired.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.
In addition, in a present Example and a comparative example, a vacuum residue is contained as evaluation oil (10% residual carbon content is 0.4 weight%), density (15 degreeC); 0.871 g / cm < ³ >, kinematic viscosity; 3 A heavy oil at 15 mm ² / s, T50; 290 ° C. was used. The low temperature fluidity test method (CFPP and corrected clogging point), wax dispersibility test and filter oil permeability test were tested by the following methods.
CFPP test method;
The test was conducted according to JIS K 2288.
Corrected clogging point test method;
Although conforming to the CFPP test, the opening of the wire mesh was set to 149 μm, the cooling rate of the cooling bath was set to 1 ° C./hour, and the cooling bath temperature at which the suction time became 30 seconds or more for the first time was taken as the corrected clogging point. Suction was limited to one time per sample, and the sample once sucked was not sucked again.
Wax dispersibility test method;
(1) 100 ml of fuel oil to be tested was collected in a 100 ml measuring cylinder with a stopper.
(2) (1) was put into an air bath with a temperature adjustment function, and kept at a temperature 5 ° C. higher than CP for 2 hours.
(3) The air bath was cooled at a cooling rate of 1 ° C./hour and cooled to the test temperature (lower than CP).
(4) Holding at the test temperature for 2 hours, the ratio of the precipitated and precipitated wax layer (= W) to the upper clarified layer (= C) was determined by the following formula (i).
WD (%) = 100 × W / (W + C) (i)
In addition, the value of WD becomes large in the fuel oil with good dispersibility of the wax.
Filter oil permeability test;
(1) 550 ml of the fuel oil to be tested was dispensed into a beaker.
(2) (1) was put into an air bath with a temperature adjustment function and allowed to stand at the test temperature for 20 hours.
(3) The inside of the beaker is stirred at the test temperature, and the filtration is performed under reduced pressure under the conditions of filtration diameter: 3.5 cm (filtration area: 9.62 cm ² ), filter opening: 5 μm, degree of vacuum: 50.7 kPa (380 mmHg). did.
(4) At this time, every time 100 ml of fuel oil was filtered, the filtration time was measured to determine the filtration rate.
In addition, in the fuel oil with favorable filter oil permeability, a filtration speed becomes quick.

Example 1 of Compound A
Normal paraffin wax 140 manufactured by Nippon Seiwa Co., Ltd., having a melting point of 61 ° C. and a penetration of 11 at 25 ° C. and an average molecular weight of 404 by gas chromatography was designated as Compound H-1.
Example 2 of Compound A
Normal paraffin wax 120 manufactured by Nippon Seiwa Co., Ltd., having a melting point of 50 ° C. and a penetration of 23 at 25 ° C. and an average molecular weight of 344 by gas chromatography, was designated as Compound H-2.
Example 3 of Compound A
Compound H-3 was a microcrystalline wax Hi-Mic-1045 manufactured by Nippon Seiwa Co., Ltd. having a melting point of 70 ° C., a penetration of 30 at 25 ° C. and a molecular weight range of 500 to 800.
Example 4 of Compound A
Compound H-4 was a microcrystalline wax Hi-Mic-2065 manufactured by Nippon Seiwa Co., Ltd. having a melting point of 75 ° C. and a penetration of 12 at 25 ° C. and a molecular weight range of 500 to 800.

Production Example 1 (Example 1 of Compound B)
In a reactor equipped with a stirrer, a nitrogen blowing tube and a condenser, a neutralization value of 346 mg KOH / g (hexadecenyl succinic anhydride about 70%, octadecenyl succinic anhydride about 25%, other As an ingredient, 324 g (1 mol) of alkenyl succinic anhydride (containing about 3% of olefins having 16 and 18 carbon atoms as impurities) was charged, and dihydrogenated tallow amine (total amine value 115 mgKOH / g) while continuing stirring. Kao's Farmin D86, the alkyl group has a typical composition of C14; 4%, C16; 30%, C18; 66% dialkylamine, the same shall apply hereinafter) 513 g (1.05 mol), heated to 100 ° C., The target compound S-1 was obtained by aging at 100 ° C. for 3 hours.

Production Example 2 (Example 2 of Compound B)
A reactor equipped with a stirrer, a nitrogen blowing tube and a condenser was charged with 210 g (1 mol) of alkenyl succinic anhydride having a neutralization value of 535 mg KOH / g (about 99% octenyl succinic anhydride), and stirring was continued. 470 g (1.8 mol) of hydrogenated tallow amine (Kao-Farmin T, representative composition of alkyl groups: C14; 4%, C16; 30%, C18; 66% monoalkylamine) having a total amine value of 215 mgKOH / g The resulting mixture was heated to 80 ° C. and aged at 80 ° C. for 3 hours to obtain the target compound S-2.

Production Example 3 (Example 3 of Compound B)
In a reactor equipped with a stirrer, a nitrogen blowing tube and a condenser, a neutralization value of 346 mg KOH / g (hexadecenyl succinic anhydride about 70%, octadecenyl succinic anhydride about 25%, other As an ingredient, 324 g (1 mol) of alkenyl succinic anhydride (containing about 3% of olefins having 16 and 18 carbon atoms as impurities) was charged, and dihydrogenated tallow amine (total amine value 115 mgKOH / g) while continuing stirring. (Farmin D86) was charged with 732 g (1.5 mol), heated to 100 ° C., and aged at 100 ° C. for 3 hours to obtain the target compound S-3.

Production Example 4 (Example 4 of Compound B)
In a reactor equipped with a stirrer, a nitrogen blowing tube and a condenser, neutralization value: 325 mg KOH / g (octadecenyl succinic anhydride about 90%, hexadecenyl succinic acid about 5%, as other components 345 g (1 mol) of alkenyl succinic anhydride (containing about 3% of olefins having 16 and 18 carbon atoms as impurities), and with continued stirring, a dihydrogenated tallow amine (Farmin D86 with a total amine number of 115 mg KOH / g) ) (878 g (1.5 mol)), heated to 100 ° C. and aged at 100 ° C. for 3 hours to obtain the intended compound S-4.

Comparative compound 1
An ethylene-vinyl acetate copolymer having a number average molecular weight of 2,300 and a vinyl acetate copolymerization ratio of 30% by weight was designated as Compound R-1.
Comparative compound 2
An ethylene-vinyl acetate copolymer having a number average molecular weight of 3000 and a vinyl acetate copolymerization ratio of 27% by weight was designated as Compound R-2.

Table 1 shows the results of performing a low temperature fluidity test (CFPP and modified clogging point test) by adding compound A and compound B in combination to fuel oil. As a comparative example, the test result when no additive was added (blank), the test result when compound A or B was added alone, and the test results of comparative compounds 1 and 2 were also shown.
Table 2 shows the results of combining the compound A and the compound B and adding them to the fuel oil and conducting the filter oil permeability test at + 5 ° C. In addition, the test result of the blank and the comparative compound 2 was also written together as a comparative example.
Table 3 shows the results of a combination of compound A and compound B added to fuel oil and a wax dispersibility test conducted at -8 ° C. As a comparative example, the test results of comparative compounds 1 and 2 are also shown.

When Examples 1-12 listed in Table 1 and Comparative Examples 1-8 are compared, all of Examples 1-12 are improved in low-temperature performance (CFPP and corrected clogging point) than Comparative Examples 1-8. It can be confirmed.
In Table 2, as shown in Comparative Examples 6 to 8, it was confirmed that the ethylene-vinyl acetate copolymer significantly deteriorated the filter oil permeability when the addition amount exceeded 500 mg / L. No. 10, it was confirmed that the filter oil permeability did not deteriorate even when the added amount was 800 mg / L.
Furthermore, in Table 3, although ethylene-vinyl acetate copolymer is not improving the wax dispersibility as Comparative Examples 5-7, in Examples 1-12, the wax dispersibility is remarkably improved.

Claims (6)

The compound A represented by the following general formula (1) and the compound B represented by the following general formula (2) are mixed so that the weight ratio (compound A) :( compound B) is 1:99 to 50:50. Contains low-temperature fluidity improver for fuel oil.

(In the formula, n represents an integer of 2 or more, and X ^{1 to} X ⁸ each independently represent hydrogen, a linear hydrocarbon group or a branched hydrocarbon group, or a cyclohydrocarbon group having 3 or more carbon atoms.)

(In the formula, one of X ⁹ and X ¹⁰ is a linear or branched hydrocarbon group having 8 to 24 carbon atoms, the other represents hydrogen, and X ¹¹ represents NR ¹ R ² or NHR ³ , X ¹² is H ⁺ , HN ⁺ HR ⁴ R ^5, or HN ⁺ H ₂ R ⁶ , and R ^{1 to} R ⁶ each independently represents a hydrocarbon group having 8 to 24 carbon atoms. The low temperature fluidity improver according to claim 1, wherein the compound A has 20 to 100 carbon atoms. The low-temperature fluidity improver according to claim 1 or 2, wherein compound A is one or more compounds selected from normal paraffin, isoparaffin, cycloparaffin, and microcrystalline wax. A residual oil containing 10 mg / L to 2000 mg / L of the low-temperature fluidity improver according to any one of claims 1 to 3 and having good filter oil permeability at a temperature higher than the cloud point of the fuel oil. A fuel oil composition. A residual oil containing 10 mg / L to 2000 mg / L of the low-temperature fluidity improver according to any one of claims 1 to 3 and having good wax dispersibility at a temperature lower than the cloud point of the fuel oil. A fuel oil composition. The compound A and the compound B according to any one of claims 1 to 3, wherein the weight ratio (compound A) :( compound B) is 10 mg / L to 2000 mg / L in a range of 1:99 to 50:50. Fuel oil containing residual oil having good filter oil permeability at a temperature higher than the cloud point of the fuel oil added so as to have a concentration and good wax dispersibility at a temperature lower than the cloud point of the fuel oil Composition.