Fuel oil composition and method for producing the same

Abstract

By incorporating fatty acid alkyl esters and cracked diesel fractions in predetermined amounts, this invention provides a fuel oil composition that offers excellent fuel efficiency and combustion performance, as well as environmental performance that reduces nitrogen oxide emissions, and excellent storage stability. [Solution] A fuel oil composition containing a fatty acid alkyl ester having specific properties and a cracked light oil fraction in a specific amount based on the total amount of the composition, and a method for producing the same.

Description

[Technical Field]

[0001] The present invention relates to a fuel oil composition and a method for producing the same. [Background technology]

[0002] JIS K2205:1991 Type 1 heavy oil (hereinafter also referred to as "A heavy oil"), and especially JIS K2205:1991 Type 1 No. 1 heavy oil (hereinafter also referred to as "low sulfur A heavy oil"), have a higher calorific value per unit volume compared to kerosene, light oil, etc., allowing for a reduction in fuel oil usage (volume). Furthermore, compared to C heavy oil (JIS K2205:1991 Type 3 heavy oil), they have lower sulfur, nitrogen, and residual carbon content, resulting in a lower environmental impact. In addition, unlike C heavy oil, they do not require heating, can be stored and used at room temperature, and have excellent supply stability. For these reasons, they are widely used as fuel oil for internal combustion engines such as marine diesel engines and as fuel oil for external combustion engines such as power generation boilers.

[0003] Fuel oils for ships that satisfy ISO 8217 "Petroleum products - Fuels (class F) - Specification of marine fuels" are known. ISO 8217:2017 added additional provisions (DF grade: DFA, DFZ, and DFB) for ship distillates with a maximum fatty acid methyl ester (FAME) content of 7% by volume or less. Fuel oil compositions containing fatty acid methyl ester (FAME) are known, for example, those described in Patent Documents 1 to 3. Patent Documents 1 to 3 disclose fuel oil compositions containing methyl esters of rapeseed oil, such as methyl myristate, in a content of 5 to 100% by volume, which are used for internal combustion engines and external combustion engines. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2007-231119 [Patent Document 2] Japanese Patent Publication No. 2007-231120 [Patent Document 3] Japanese Patent Publication No. 2007-231121 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The fatty acid alkyl esters, such as fatty acid methyl esters (FAME), contained in the fuel oil compositions described in the above-mentioned Patent Documents 1 to 3, are among the base oils whose use as fuel oils is being investigated due to their high combustion performance and fuel efficiency. Furthermore, when fatty acid alkyl esters derived from plants and animals are used, carbon dioxide emissions are reduced, thus contributing to the mitigation of global warming through carbon dioxide emission reduction, and are extremely useful from an environmental protection standpoint. Therefore, by using fatty acid alkyl esters such as fatty acid methyl esters (FAME) as a base oil, improved combustion performance can be expected, and by adopting fatty acid alkyl esters derived from plants and animals, it can become a base oil that contributes to environmental protection.

[0006] Incidentally, when using fuel oil compositions in internal combustion engines, such as marine diesel engines, the frequency of fuel oil filter clogging tends to increase during normal use due to sludge formation caused by asphaltene aggregation. Furthermore, when used after long-term storage in fuel oil tanks on ships, sludge formation becomes more likely, and the frequency of clogging tends to increase even further. As fuel oil compositions for ships, fuel oils that satisfy ISO 8217 as described above are known, but fuel oil filter clogging can still occur. As methods to reduce the frequency of clogging, methods such as reducing the latent sediment (Total sediment aged, ISO 10307-2) to 0.10 mass% or less and methods such as reducing the actual sediment (Total sediment by hot filtration, ISO 10307-1) to 0.10 mass% or less are known. However, for marine fuel oils, especially distillates, the oil flow performance in fuel oil filters after storage at room temperature is not sufficient, and there is a need for fuel oil compositions that can further reduce the frequency of clogging. Reducing the frequency of fuel oil filter blockage reduces the frequency of fuel oil filter cleaning, which in turn enables more stable operation. Thus, while storage stability is required for fuel oil compositions used in internal combustion engines of ships and the like, storage stability is also required for fuel oil compositions used in external combustion engines, just as it is for internal combustion engines.

[0007] The fuel oil compositions described in the above-mentioned Patent Documents 1 to 3 focus on reducing unburned substances (smoke) and particulate matter (PM) in exhaust gas, improving calorific value and reducing soot concentration in combustion exhaust gas, and improving sludge stability due to the reduction of sulfur content and the inclusion of residual carbon imparting agents. However, they do not focus on improving fuel flow performance by reducing the frequency of clogging, in addition to improving combustion performance, and there is room for improvement in the fuel flow performance in fuel oil filters after storage at room temperature (hereinafter also referred to as "storage stability performance"). Furthermore, while ISO 8217 sets standards for ship distillate oil with a fatty acid methyl ester (FAME) content of 7% by volume or less, it makes no mention of low-sulfur heavy oil A with a content exceeding 7% by volume. As a result, low-sulfur heavy oil A with a fatty acid alkyl ester content exceeding 7% by volume, such as fatty acid methyl ester (FAME), is prone to clogging of fuel oil filters when used after storage at room temperature, and cannot be said to have excellent storage stability performance. Therefore, further improvements are needed to enhance storage stability performance by reducing the frequency of fuel oil filter blockage when using the fuel after storage at room temperature.

[0008] Furthermore, the fatty acid alkyl esters used in the fuel oil compositions described in the above-mentioned Patent Documents 1 to 3 have excellent combustion performance and fuel efficiency, as previously mentioned, but generally nitrogen oxides (NOx) are used. X It is known that emissions of nitrogen oxides (NOx) tend to increase when fatty acid alkyl esters are used in fuel oil compositions. X There is a trade-off between reducing emissions and environmental performance. In recent years, reducing environmental impact has become an urgent issue, and there is a strong demand for improved environmental performance.

[0009] Thus, fuel oil compositions for internal and external combustion engines should have properties that contribute to stable navigation, such as combustion performance, fuel efficiency, and storage stability, as well as nitrogen oxides (NOx). XThere is a need to provide a fuel oil composition that also has excellent environmental performance in reducing emissions of nitrogen oxides (NOx). For example, external combustion engines equipped with hydraulic spray burners with a rated combustion volume of 100 L / hour or less are subject to strict cost control, so nitrogen oxides (NOx) in the combustion exhaust gas are a concern. X It is difficult to install denitrification equipment to reduce or remove nitrogen oxides (NOx) from fuel oil compositions used in such external combustion engines. X The fact that it has excellent environmental performance in reducing the emissions of nitrogen oxides (NOx) is extremely useful. X In addition to performance that reduces emissions, there is also a demand for environmental performance that can reduce the sulfur content required for conventional fuel oil compositions.

[0010] This invention has been made in view of the above circumstances, and aims to provide a fuel oil composition that is excellent in fuel efficiency and combustion performance, as well as environmental performance that reduces nitrogen oxide emissions, and also has excellent storage stability, by containing fatty acid alkyl esters and cracked light oil fractions in predetermined amounts. [Means for solving the problem]

[0011] In view of the above problems, the present inventors have diligently studied and found that they can be solved by the following invention. That is, the present invention provides a fuel oil composition having the following configuration.

[0012] [1] A fuel oil composition that satisfies all of the following (1) to (6), comprising a fatty acid alkyl ester that satisfies all of (a1) to (a3) ​​below, and a cracked light oil fraction that satisfies all of (b1) to (b4) below, wherein the fatty acid alkyl ester is an ester of a fatty acid having 8 to 22 carbon atoms and an alkyl alcohol having 1 to 4 carbon atoms, the content of the fatty acid alkyl ester on a basis of the total composition is 15.0% by volume or more and 35.0% by volume or less, and the content of the cracked light oil fraction on a basis of the total composition is more than 40.0% by volume and 60.0% by volume or less. (a1) Cetane number of 49.0 or higher (a2) The acid value is 0.50 mg KOH / g or less (a3) The residual carbon content of the 10% residual oil is 0.80% by mass or more and 1.50% by mass or less (b1) The kinematic viscosity at 50 °C is 2.600 mm 2 / s or more and 3.600 mm 2 / s or less (b2) The sulfur content is 0.400% by mass or less (b3) The aromatic content is 50.0% by volume or more (b4) The content of aromatic components with 3 or more rings is 10.0% by volume or more (1) The density at 15 °C is 0.8950 g / cm 3 or more (2) The kinematic viscosity at 50 °C is 3.000 mm 2 / s or more and 3.500 mm 2 / s or less (3) The sulfur content is 0.300% by mass or less (4) The content of aromatic components with 3 or more rings is 6.0% by volume or more (5) The residual carbon content of the 10% residual oil is 0.21% by mass or more and 0.60% by mass or less (6) The cetane number is 31.0 or more [2] The fuel oil composition according to [1] above, wherein the fatty acid alkyl ester is a fatty acid methyl ester. [3] The fuel oil composition according to [1] or [2] above, wherein the fatty acid is a mixed fatty acid containing two or more fatty acids having 8 to 22 carbon atoms. [4] The fuel oil composition according to [3] above, wherein the mixed fatty acid is obtained from at least one raw material selected from animal oils and vegetable oils. [5] The fuel oil composition according to any one of [1] to [4] above, which is used in an external combustion engine. [6] The fuel oil composition according to [5] above, wherein the external combustion engine is equipped with an oil pressure spray burner having a rated combustion amount of 100 L / hour or less. [7] A method for producing a fuel oil composition that satisfies all of the following (1) to (6), comprising mixing a fatty acid alkyl ester which is an ester of a fatty acid having 8 to 22 carbon atoms and an alkyl alcohol having 1 to 4 carbon atoms, satisfying all of the following (a1) to (a3), with a cracked light oil fraction which satisfies all of the following (b1) to (b4), such that the fatty acid alkyl ester content on a basis of the total composition is 15.0% by volume or more and 35.0% by volume or less, and the cracked light oil fraction content on a basis of the total composition is more than 40.0% by volume and 60.0% by volume or less. (a1) Cetane number of 49.0 or higher (a2) Acid value is 0.50 mgKOH / g or less (a3) The residual carbon content of the 10% residual oil is 0.80% by mass or more and 1.50% by mass or less. (b1) Kinematic viscosity at 50°C is 2,600 mm 2 / s or more 3.600mm 2 / s or less (b2) Sulfur content is 0.400% by mass or less (b3) Aromatic content of 50.0% or more by volume (b4) Aromatic content of 3 or more rings is 10.0% or more by volume. (1) Density at 15℃ is 0.8950 g / cm³ 3 That's all. (2) The kinematic viscosity at 50°C is 3,000 mm 2 / s or more 3.500mm 2 / s or less (3) Sulfur content is 0.300% by mass or less (4) Aromatic content of 3 or more rings is 6.0% or more by volume. (5) The residual carbon content of the 10% residual oil is 0.21% by mass or more and 0.60% by mass or less. (6) Cetane number of 31.0 or higher [Effects of the Invention]

[0013] According to the present invention, by incorporating fatty acid alkyl esters and cracked light oil fractions in predetermined amounts, it is possible to provide a fuel oil composition that is excellent in fuel efficiency and combustion performance, as well as environmental performance that reduces nitrogen oxide emissions, and also has excellent storage stability. [Modes for carrying out the invention]

[0014] The following describes in detail the fuel oil compositions according to embodiments of the present invention (hereinafter sometimes simply referred to as "this embodiment"). In this specification, the numerical values ​​related to "less than or equal to," "greater than or equal to," and "~" in numerical range descriptions are arbitrary combinations. For example, if a numerical range is described as "A~B" and "C~D," it also includes numerical ranges such as "A~D" and "C~B." Furthermore, the numerical values ​​in the examples can be used as upper or lower limits.

[0015] [Fuel oil composition] The fuel oil composition of this embodiment is a fuel oil composition that satisfies all of the following (1) to (6), comprising a fatty acid alkyl ester satisfying all of (a1) to (a3) ​​below, and a cracked diesel fraction satisfying all of (b1) to (b4) below, wherein the fatty acid alkyl ester is an ester of a fatty acid having 8 to 22 carbon atoms and an alkyl alcohol having 1 to 4 carbon atoms, the content of the fatty acid alkyl ester on a basis of the total composition is 15.0% by volume or more and 35.0% by volume or less, and the content of the cracked diesel fraction on a basis of the total composition is greater than 40.0% by volume and 60.0% by volume or less. (a1) Cetane number of 49.0 or higher (a2) Acid value is 0.50 mgKOH / g or less (a3) The residual carbon content of the 10% residual oil is 0.80% by mass or more and 1.50% by mass or less. (b1) Kinematic viscosity at 50°C is 2,600 mm 2 / s or more 3.600mm 2 / s or less (b2) Sulfur content is 0.400% by mass or less (b3) Aromatic content of 50.0% or more by volume (b4) Aromatic content of 3 or more rings is 10.0% or more by volume. (1) Density at 15℃ is 0.8950 g / cm³ 3 That's all. (2) The kinematic viscosity at 50°C is 3,000 mm 2 / s or more 3.500mm2 / s or less (3) Sulfur content is 0.300% by mass or less (4) Aromatic content of 3 or more rings is 6.0% or more by volume. (5) The residual carbon content of the 10% residual oil is 0.21% by mass or more and 0.60% by mass or less. (6) Cetane number of 31.0 or higher

[0016] (Composition and properties of fuel oil composition) The fuel oil composition of this embodiment satisfies all of the following compositional and property requirements (1) to (6). (1) Density at 15℃ The density of the fuel oil composition of this embodiment at 15°C is 0.8950 g / cm³. 3 That concludes the explanation. If the density at 15°C is outside the above range, a decrease in combustion performance, fuel efficiency, and storage stability may occur.

[0017] From the viewpoint of improving combustion performance, fuel efficiency, and storage stability, the density of the fuel oil composition of this embodiment at 15°C is preferably 0.8960 g / cm³. 3 More preferably 0.8980 g / cm³ 3 More preferably 0.9000 g / cm³ 3 The above is true, and preferably the upper limit is 0.9200 g / cm³. 3 More preferably, 0.9150 g / cm³ 3 The following applies: In this specification, the density at 15°C is the value measured in accordance with JIS K 2249-1:2011 (Crude oil and petroleum products - Method for determining density - Part 1: Vibration method).

[0018] (2) Kinematic viscosity at 50°C The kinematic viscosity of the fuel oil composition of this embodiment at 50°C is 3,000 mm². 2 / s or more 3.500mm 2The kinematic viscosity at 50°C must be less than or equal to / s. If the kinematic viscosity at 50°C is outside the above range, combustion performance and environmental performance in reducing nitrogen oxide emissions may be reduced. In addition, it may become difficult to use the fuel oil composition with various equipment such as pumps and flow meters, and lubrication may not be ensured.

[0019] The kinematic viscosity of the fuel oil composition of this embodiment at 50°C is preferably 3,100 mm, from the viewpoint of improving combustion performance and environmental performance, making it easier to adapt to the operating range of various devices, and improving lubricity. 2 / s or more, more preferably 3,200 mm 2 The value is 1 / s or more, and preferably has an upper limit of 3,400 mm. 2 / s or less, more preferably 3.350 mm 2 It is less than or equal to / s. In this specification, the kinematic viscosity at 50°C is the value measured in accordance with JIS K 2283:2000 (Test method for kinematic viscosity of crude oil and petroleum products).

[0020] (3) Sulfur content The sulfur content of the fuel oil composition in this embodiment is 0.300% by mass or less. If the sulfur content is outside this range, corrosion may occur due to an increase in sulfur oxides in the exhaust gas, and the environmental burden may increase, potentially leading to a decrease in environmental performance.

[0021] Considering the suppression of corrosion and the improvement of environmental performance, the sulfur content is preferably 0.250% by mass or less, more preferably 0.200% by mass or less, and even more preferably 0.160% by mass or less. Furthermore, the lower the sulfur content, the better, and there is no particular lower limit, but from the viewpoint of improving storage stability and lubricity, it is usually 0.03% by mass or more. In this specification, the sulfur content other than fatty acid alkyl esters is measured by selecting a measurement method according to the content, and when the content is 0.01 to 5% by mass, the value is measured in accordance with JIS K 2541-4:2003 (Crude oil and petroleum products - Sulfur content test method - Part 4: Radiation excitation method).

[0022] (4) Content of aromatic compounds with 3 or more rings The content of aromatic compounds with three or more rings in the fuel oil composition of this embodiment is 6.0% by volume or more. If the content of aromatic compounds with three or more rings is not within the above range, the storage stability performance will decrease. From the viewpoint of improving the storage stability performance of the fuel oil composition, it is preferably 6.2% by volume or more, more preferably 6.5% by volume or more, and even more preferably 7.0% by volume or more, and there is no particular upper limit, but it is usually 10.0% by volume or less. In this specification, the content of aromatic components other than the heavy oil fraction (residual carbon source) described later (mono-ring aromatic components, bi-ring aromatic components, and tri-ring or more aromatic components), as well as the content of saturated components and olefin components, are values ​​measured by the High Performance Liquid Chromatography method, as specified in JPI-5S-49-2007, which defines petroleum products - hydrocarbon type test methods.

[0023] (5) Residual carbon content of 10% residual oil The residual carbon content of the 10% residual oil of the fuel oil composition of this embodiment is 0.21% by mass or more and 0.60% by mass or less. If the residual carbon content of the 10% residual oil exceeds 0.60% by mass, it becomes difficult to maintain combustion performance, sludge is more likely to form, and storage stability performance decreases. Furthermore, by setting it to 0.21% by mass or more, the fuel oil composition of this embodiment can be treated as heavy oil A and can be exempted from light oil tax, thus providing tax benefits. From the viewpoint of improving combustion performance and storage stability performance, and considering tax benefits, the residual carbon content of the 10% residual oil is preferably 0.22% by mass or more, more preferably 0.23% by mass or more, with an upper limit of preferably 0.50% by mass or less, and more preferably 0.45% by mass or less. In this specification, the residual carbon content of 10% residual oil is the value measured using 10% residual oil prepared in accordance with JIS K 2270-2:2009 (Crude oil and petroleum products - Method for determining residual carbon content - Part 2: Microscopic method) and Annex A.

[0024] (6) Cetane number The cetane number of the fuel oil composition in this embodiment is 31.0 or higher. If the cetane number is less than 31.0, the combustion performance will decrease. From the viewpoint of improving combustion performance, the cetane number is preferably 31.5 or higher, more preferably 32.0 or higher, and there is no particular upper limit, but it is usually 41.0 or lower. In this specification, the cetane number is a value determined in accordance with JIS K 2280-4:2013 (Petroleum products - Method for determining octane number, cetane number and cetane index - Part 4: Cetane number).

[0025] Furthermore, in addition to the properties and composition of (1) to (6) above, the fuel oil composition of this embodiment preferably satisfies at least one of the properties and composition selected from (7) to (1213) below, and it is particularly preferable that it satisfies all of the properties and composition of (7) to (1213) below.

[0026] (7) Flash point From the viewpoint of handling safety, the flash point of the fuel oil composition of this embodiment is preferably 60.0°C or higher, more preferably 65.0°C or higher, and even more preferably 70.0°C or higher. There is no particular upper limit, but it is usually 100.0°C or lower. In this specification, the flash points other than those of fatty acid alkyl esters are values ​​measured in accordance with JIS K 2265-3:2007 (Crude oil and petroleum products - Flash point test methods - Part 3: Pennsky-Haltens closed method).

[0027] (8) Moisture content The water content of the fuel oil composition of this embodiment is preferably 0.10% by volume or less, and more preferably less than 0.10% by volume. There is no particular lower limit, as a smaller limit is preferable. When the water content is within the above range, the formation of sludge due to the emulsion of asphaltene and water, as well as the occurrence of freezing, can be suppressed during storage at room temperature, thereby reducing the frequency of blockage in the fuel oil filter and improving storage stability performance. In this specification, the water content other than fatty acid alkyl esters is the value measured in accordance with JIS K 2275-1:2015 (Crude oil and petroleum products - Method for determining water content - Part 1: Distillation method).

[0028] (9) Copper plate corrosion In this embodiment, the copper plate corrosion of the fuel oil composition is preferably 1 or less (1a or 1b) in terms of the copper plate classification for copper plate determination, and more preferably 1a. If the copper plate corrosion is 1 or less, corrosion of the fuel oil tank, piping, diesel engine, and various auxiliary equipment such as pumps can be prevented, thereby enabling more stable operation of various equipment such as internal combustion engines and external combustion engines. In this specification, copper plate corrosion is measured in accordance with JIS K 2513:2000 (Petroleum products - Test method for copper plate corrosion). Here, the test temperature is 50°C and the test time is 3 hours.

[0029] (10) Acid value The acid value of the fuel oil composition of this embodiment is preferably 0.15 mg KOH / g or less, more preferably 0.10 mg KOH / g or less, and even more preferably less than 0.10 mg KOH / g. The lower the acid value, the better, and there is no particular lower limit, but it is particularly preferably 0.0 mg KOH / g. When the acid value is within the above range, the frequency of blockage in the fuel oil filter can be reduced by suppressing sludge formation, thereby improving storage stability and further suppressing corrosion of storage tanks, piping, and other components when stored at room temperature. In this specification, the acid value is the value measured in accordance with "7. Potentiometric titration method (acid value)" as specified in JIS K 2501:2003 (Petroleum products and lubricating oils - Neutralization value test method).

[0030] (11) Pour point The pour point of the fuel oil composition of this embodiment is preferably -10.0°C or lower, more preferably -12.5°C or lower, and even more preferably -15.0°C or lower. There is no particular lower limit, but it is usually -35.0°C or higher. When the pour point is within the above range, the fluidity in storage tanks and piping at low temperatures is improved, and handling is also improved. In this specification, the pour point is a value measured in accordance with JIS K 2269:1987 (Test method for pour point and cloud point of crude oil and petroleum products).

[0031] (12)Nitrogen content The nitrogen content of the fuel oil composition of this embodiment is preferably 250 ppm by mass or less, more preferably 230 ppm by mass or less, and even more preferably 200 ppm by mass or less. There is no particular lower limit, but it is usually 100 ppm by mass or more. When the nitrogen content is within the above range, nitrogen oxides (NOx) are produced. X This reduces emissions, thus improving environmental performance. In this specification, the nitrogen content is the value measured in accordance with JIS K 2609:1998 (Crude oil and petroleum products - Test method for nitrogen content).

[0032] (13) Total heat generation The total calorific value of the fuel oil composition of this embodiment is preferably 38.7 MJ / L or more, more preferably 38.8 MJ / L or more, and even more preferably 38.9 MJ / L or more. The upper limit is preferable as high as possible, and is usually 43.0 MJ / L or less. When the total calorific value is within the above range, fuel efficiency is improved. In this specification, the total calorific value is the value obtained by multiplying the "Gross heat of combustion," measured according to the test method specified in "Standard Test Method for Heat of Combustion of Liquid Hydrocarbon Fuels by Bomb Calorimeter" (ASTM D240-9), by the density and converting it to a value per volume.

[0033] (Alkyl fatty acid ester) The fuel oil composition of this embodiment satisfies all of the following (a1) to (a3) ​​and contains a fatty acid alkyl ester, which is an ester of a fatty acid having 8 to 22 carbon atoms and an alkyl alcohol having 1 to 4 carbon atoms, in an amount of 15.0% to 35.0% by volume based on the total amount of the composition. (a1) Cetane number of 49.0 or higher (a2) Acid value is 0.50 mgKOH / g or less (a3) The residual carbon content of the 10% residual oil is 0.80% by mass or more and 1.50% by mass or less.

[0034] (a1) Cetane number The cetane number of the fatty acid alkyl ester is 49.0 or higher. Fatty acid alkyl esters are known as oils with a high cetane number, and by using fatty acid alkyl esters, the cetane number of the fuel oil composition of this embodiment can be improved, thereby improving combustion performance. Therefore, if the cetane number of the fatty acid alkyl ester is less than 49.0, it becomes difficult to achieve a cetane number of 31.0 or higher in the fuel oil composition of this embodiment, and combustion performance decreases. From the viewpoint of improving combustion performance, the cetane number of the fatty acid alkyl ester is preferably 50.0 or higher, more preferably 51.0 or higher. There is no particular upper limit, but it is usually 70.0 or lower.

[0035] (a2) Acid value The acid value of the fatty acid alkyl ester is 0.50 mgKOH / g or less. If the acid value of the fatty acid alkyl ester is outside the above range, the suppression of sludge formation will increase the frequency of blockage in the fuel oil filter, reducing storage stability performance, and corrosion of storage tanks, piping, and other components may occur when stored at room temperature. From the viewpoint of improving storage stability performance and suppressing corrosion of components, the acid value of the fatty acid alkyl ester is preferably 0.48 mgKOH / g or less, more preferably 0.47 mgKOH / g or less, and even more preferably 0.46 mgKOH / g or less, with no particular lower limit, and is usually 0.05 mgKOH / g or more.

[0036] (a3) Residual carbon content of 10% residual oil The residual carbon content of the 10% residue of the fatty acid alkyl ester is between 0.80% by mass and 1.50% by mass. If the residual carbon content of the 10% residue of the fatty acid alkyl ester is not within the above range, it becomes difficult to maintain the residual carbon content of the 10% residue of the fuel oil composition of this embodiment at between 0.21% by mass and 0.60% by mass, making it difficult to maintain combustion performance. In addition, it may become difficult to reduce the frequency of blockage in the fuel oil filter, potentially leading to a decrease in storage stability performance. In order to make it easier to set the residual carbon content of the 10% residual oil of the fuel oil composition of this embodiment to 0.21% by mass or more and 0.60% by mass or less, and to improve combustion performance and storage stability, the residual carbon content of the 10% residual oil of the fatty acid alkyl ester is preferably 0.85% by mass or more, more preferably 0.90% by mass or more, with an upper limit of preferably 1.40% by mass or less, more preferably 1.30% by mass or less, even more preferably 1.15% by mass or less, and even more preferably 1.00% by mass or less. Furthermore, if the residual carbon content of the 10% residual oil of the fatty acid alkyl ester is within the above range, it becomes easier to enjoy tax benefits.

[0037] (Fatty acids and alkyl alcohols) A fatty acid alkyl ester is, in a broad sense, an ester of a fatty acid and an alkyl alcohol. The fatty acid alkyl ester used in this embodiment is an ester of a fatty acid having 8 to 22 carbon atoms and an alkyl alcohol having 1 to 4 carbon atoms, and satisfies all of the above (a1) to (a3).

[0038] As for the fatty acids, either saturated or unsaturated fatty acids can be used. Among fatty acids with 8 to 22 carbon atoms, typical and preferred saturated fatty acids include caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, palmitoleic acid, margaric acid, stearic acid, nonadecylic acid, arachidic acid, henicosyl acid, and behenic acid.

[0039] Furthermore, as unsaturated fatty acids, monounsaturated fatty acids such as myristoleic acid, palmitoleic acid, oleic acid, eicosenoic acid, and erucic acid; and polyunsaturated fatty acids such as linoleic acid, linolenic acid, stearidonic acid, eicosadienoic acid, meadic acid, arachidonic acid, eicosapentaenoic acid, docosadenoic acid, docosapentaenoic acid, and docosahexaenoic acid are typically preferred.

[0040] The fatty acid may be one type or a mixed fatty acid containing two or more types, and the fatty acid alkyl ester is as described in (a1) to (a3) ​​above, and further as described in (a4) to (a 11 To make it easier to satisfy all of the above conditions and to improve combustion performance and storage stability, it is preferable to use a mixed fatty acid containing two or more types. That is, it is preferable to use two or more fatty acid alkyl esters using a mixed fatty acid containing two or more types, as described later. Furthermore, while the fatty acids mentioned above are representative examples of straight-chain fatty acids, any fatty acid can be either straight-chain or branched-chain fatty acids, as long as it has 8 to 22 carbon atoms.

[0041] Examples of alkyl alcohols having 1 to 4 carbon atoms include methanol, ethanol, propanol, and butanol. Propanol and butanol may have a linear chain or a branched chain. Alkyl fatty acid esters are as described in (a1) to (a3) ​​above, and also as described in (a4) to (a 11 To make it easier to satisfy all of the above conditions, improve combustion performance and storage stability, and considering the ease of production of fatty acid alkyl esters, the number of carbon atoms is preferably 3 or less, more preferably 2 or less, i.e., methanol or ethanol, and particularly preferably methanol. Therefore, fatty acid methyl esters are particularly preferred as the fatty acid alkyl esters used in this embodiment.

[0042] In this embodiment, one type of fatty acid alkyl ester may be used alone, or two or more types may be used in combination. The fatty acid alkyl ester is as described in (a1) to (a3) ​​above, and further as described in (a4) to (a 11 In order to make it easier to satisfy all of the above conditions and to improve combustion performance and storage stability, it is preferable to use two or more types in combination. Examples of combinations of two or more types include two or more fatty acid alkyl esters formed by two or more fatty acids and one alkyl alcohol, two or more fatty acid alkyl esters formed by one fatty acid and two or more alkyl alcohols, and any of these may be used in this embodiment.

[0043] Alkyl fatty acid esters are as described in (a1) to (a3) ​​above, and also as described in (a4) to (a 11 To make it easier to satisfy all of the above conditions and to improve combustion performance and storage stability, it is preferable to use two or more fatty acid alkyl esters made of two or more fatty acids and one alkyl alcohol. When using two or more fatty acids, for example, the fatty acids exemplified above may be mixed and used, or a mixed fatty acid containing two or more fatty acids may be used. Preferred mixed fatty acids include, for example, fatty acids obtained from animal oils, vegetable oils, etc. By using these animal and plant-derived fatty acids obtained from animal and vegetable oils, it is possible to contribute to mitigating global warming by reducing carbon dioxide emissions, which is extremely useful from the standpoint of environmental protection.

[0044] Typical preferred animal oils used as raw materials for mixed fatty acids include beef tallow, pork tallow, mutton tallow, whale oil, fish oil, and liver oil. Typical preferred vegetable oils include linseed oil, safflower oil, sunflower oil, soybean oil, corn oil, cottonseed oil, sesame oil, olive oil, castor oil, peanut oil, coconut oil, palm kernel oil, rapeseed oil, and rice bran oil. When using naturally derived raw materials such as animal oils and vegetable oils, pretreatment may be performed as necessary before preparing fatty acid alkyl esters by esterification reaction with alkyl alcohols. For example, pretreatment by purification such as distillation or clay treatment may be performed.

[0045] When using two or more fatty acids, it is preferable that the two or more fatty acid alkyl esters include fatty acid alkyl esters of an unsaturated fatty acid with 18 carbon atoms and an alkyl alcohol, and among the unsaturated fatty acids with 18 carbon atoms, it is more preferable that they include fatty acid alkyl esters of oleic acid, linoleic acid, and linolenic acid, i.e., alkyl oleate esters, alkyl linoleate esters, and alkyl linolenic acid esters. In this case, the total content of the fatty acid alkyl ester, which consists of an unsaturated fatty acid with 18 carbon atoms and an alkyl alcohol, is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 75% by mass or more, and particularly preferably 80% by mass or more. There is no particular upper limit, but it is preferable to keep it at 95% by mass or less. If the total content of the fatty acid with 18 carbon atoms is within the above range, the fatty acid alkyl ester is as described in (a1) to (a3) ​​above, and further as described in (a4) to (a 11 Since it is easier to satisfy all of the above conditions, combustion performance and storage stability performance are improved.

[0046] As the raw material for the above mixed fatty acids, vegetable oil is preferred, and rapeseed oil is particularly preferred. Furthermore, as the raw material for the mixed fatty acids, waste cooking oil is preferred, waste cooking oil containing vegetable oil is more preferred, and waste cooking oil containing rapeseed oil is even more preferred. By using waste cooking oil for animal and vegetable oils, competition with food can be avoided, and environmental protection can be achieved through the reuse of waste. Similar to the natural raw materials such as animal oils and vegetable oils mentioned above, waste cooking oil may be pretreated as needed before preparing fatty acid alkyl esters by esterification reaction with alkyl alcohols. For example, pretreatment by purification such as distillation or clay treatment may be performed.

[0047] In this embodiment, when using animal or plant-derived fatty acids as the mixed fatty acids, the mixture may also contain fatty acids other than those with 8 to 22 carbon atoms, i.e., fatty acids with 7 or fewer carbon atoms and 23 or more carbon atoms. In this case, the content of fatty acids with 8 to 22 carbon atoms in the mixed fatty acids is preferably 90% by mass or more, more preferably 92% by mass or more, and even more preferably 95% by mass or more. That is, the content of fatty acids other than those with 8 to 22 carbon atoms is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less. The lower limit is preferably as low as possible and there is no particular restriction, but it is usually 0.5% by mass or more.

[0048] Alkyl fatty acid esters have the properties and composition described in (a1) to (a3) ​​above, and also the following (a4) to (a 11 Preferably, it satisfies at least one property and composition selected from ), and the following (a4)~(a 11 It is more preferable that both the properties and composition of the product are satisfied.

[0049] (a4) Density at 15℃ The density of the fatty acid alkyl ester at 15°C is preferably 0.8700 g / cm³. 3 More preferably 0.8750 g / cm³ 3 More than 0.8800g / cm 3 The above applies, with a preferred upper limit of 0.9000 g / cm³. 3 More preferably, 0.8900 g / cm³ 3 More preferably, 0.8850 g / cm³ 3 The following applies: If the density at 15°C is within the above range, the density of the fuel oil composition of this embodiment at 15°C is 0.8950 g / cm³. 3 This makes it easier to achieve the above, resulting in improved combustion performance, fuel efficiency, and storage stability.

[0050] (a5) Kinematic viscosity at 50°C The kinematic viscosity of the fatty acid alkyl ester at 50°C is preferably 3,000 mm². 2 / s or more, more preferably 3,200 mm 2 / s or more, more preferably 3,300 mm 2 The value is 1 / s or more, and preferably has an upper limit of 4,500 mm. 2 / s or less, more preferably 4,000 mm 2 / s or less, more preferably 3,900 mm 2 It is less than or equal to / s. If the kinematic viscosity at 50°C is within the above range, the kinematic viscosity of the fuel oil composition of this embodiment at 50°C is 3,000 mm². 2 / s or more 3.500mm 2 This makes it easier to achieve a flow rate of less than / s, improving combustion performance and environmental performance by reducing nitrogen oxide emissions. It also makes it easier to fit various equipment such as pumps and flow meters into the operating range, and improves lubricity.

[0051] (a6) Sulfur content The sulfur content of the fatty acid alkyl ester is preferably 3 ppm by mass or less, and the lower limit is preferable as much as possible, so there are no particular restrictions. When the sulfur content is within the above range, it is easier to set the sulfur content of the fuel oil composition of this embodiment to 0.300% by mass or less, which further suppresses the occurrence of corrosion and improves environmental performance. In this specification, the sulfur content of fatty acid alkyl esters is the value measured in accordance with JIS K 2541-6:2013 (Crude oil and petroleum products - Sulfur content test methods - Part 6: Ultraviolet fluorescence method).

[0052] (a7) Flash point From the viewpoint of handling safety, the flash point of fatty acid alkyl esters is preferably 100.0°C or higher, more preferably 130.0°C or higher, and even more preferably 150.0°C or higher. There is no particular upper limit, but it is usually 200.0°C or lower. In this specification, the flash point of fatty acid alkyl esters is the value measured in accordance with JIS K 2265-2:2007 (Crude oil and petroleum products - Flash point test method - Part 2: Rapid equilibrium closed method).

[0053] (a8) Moisture content The moisture content of the fatty acid alkyl ester is preferably 1,000 mg / kg or less, more preferably 500 mg / kg or less, and even more preferably 250 mg / kg or less. The lower limit is preferable as much as possible, and there are no particular restrictions, but it is usually 100 mg / kg or more. When the moisture content is within the above range, the formation of sludge and the occurrence of freezing can be suppressed, and the frequency of blockage can be reduced, thereby improving storage stability. In this specification, the water content of fatty acid alkyl esters is the value measured in accordance with JIS K 2275-2:2015 (Crude oil and petroleum products - Method for determining water content - Part 2: Karl Fischer volumetric titration method).

[0054] (a9) Copper plate corrosion The corrosion of copper plates by fatty acid alkyl esters is preferably 1 or less (1a or 1b) in the classification of copper plates for evaluation, and more preferably 1a. If the copper plate corrosion is 1 or less, corrosion of various auxiliary equipment can be prevented, thus enabling more stable operation of various equipment such as internal combustion engines and external combustion engines.

[0055] (a 10 ) Pour point The pour point of the fatty acid alkyl ester is preferably -0.0°C or lower, more preferably -2.5°C or lower. There is no particular lower limit, but it is usually -20.0°C or higher. When the pour point is within the above range, the fluidity in storage tanks and piping at low temperatures is improved, and handling is also improved.

[0056] (a 11 ) Compositional analysis The compositional analysis of fatty acid alkyl esters can be performed by gas chromatography analysis using a flame ionization detector (FID) in accordance with the Standard Method for Analysis of Fats and Oils (established by the Japan Oil Chemists' Society in 1993), "2.4.21.3-77 Fatty Acid Composition (FID Temperature-Increased Gas Chromatography Method)".

[0057] As the fatty acid alkyl ester, it is preferable to include a fatty acid alkyl ester of a mixed fatty acid containing at least oleic acid, linoleic acid, and linolenic acid, as described above, and an alkyl alcohol. The total content of the fatty acid alkyl ester of the mixed fatty acid containing at least oleic acid, linoleic acid, and linolenic acid and an alkyl alcohol, based on the total amount of fatty acid alkyl ester, is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 75% by mass or more, and particularly preferably 80% by mass or more, as described above, and there is no particular upper limit, but it is preferable to keep it at 95% by mass or less.

[0058] When the fatty acid alkyl ester contains two or more fatty acid alkyl esters, it is preferable that it contains at least an oleate alkyl ester, a linoleate alkyl ester, and a linolenic acid alkyl ester (a fatty acid alkyl ester of an unsaturated fatty acid with 18 carbon atoms and an alkyl alcohol), as described above. Furthermore, it is more preferable to include alkyl stearate (a fatty acid alkyl ester of a saturated fatty acid having 18 carbon atoms and an alkyl alcohol), even more preferable to include alkyl palmitate (a fatty acid alkyl ester of a saturated fatty acid having 16 carbon atoms and an alkyl alcohol), even more preferable to include alkyl arachidinate and alkyl erucate (fatty acid alkyl esters of saturated fatty acids having 20 and 22 carbon atoms and an alkyl alcohol), as well as alkyl eicosenoate and alkyl behenate (fatty acid alkyl esters of unsaturated fatty acids having 20 and 22 carbon atoms and an alkyl alcohol), and it is particularly preferable to include at least one selected from alkyl caprylate, alkyl caprate, alkyl laurate, and alkyl myristate.

[0059] (Content of fatty acid alkyl esters) The fatty acid alkyl ester content on a basis of the total composition is 15.0% by volume or more and 35.0% by volume or less. If the fatty acid alkyl ester content is less than 15.0% by volume, the combustion performance decreases, and if it exceeds 35.0% by volume, the storage stability performance decreases. From the viewpoint of improving combustion performance and storage stability performance, the fatty acid alkyl ester content on a basis of the total composition is preferably 17.5% by volume or more, more preferably 20.0% by volume or more, and preferably 32.5% by volume or less as the upper limit.

[0060] (Cracked diesel fraction) The fuel oil composition of this embodiment contains cracked diesel fraction in an amount of more than 40.0% by volume and 60.0% by volume or less on a basis of the total amount of the composition. The cracked diesel fraction is a catalytically cracked diesel fraction obtained by fluid catalytic cracking of atmospheric distillation residue oil and / or vacuum distillation residue oil. The cracked diesel fraction used in this embodiment is one of the above fractions that satisfies the following properties and composition (b1) to (b4). (b1) Kinematic viscosity at 50°C is 2,600 mm 2 / s or more 3.600mm 2 / s or less (b2) Sulfur content is 0.400% by mass or less (b3) Aromatic content of 50.0% or more by volume (b4) Aromatic content of 3 or more rings is 10.0% or more by volume.

[0061] (b1) Kinematic viscosity at 50°C The kinematic viscosity of the cracked diesel fraction at 50°C is 2,600 mm². 2 / s or more 3.600mm 2 It is less than or equal to / s. If the kinematic viscosity at 50°C is not within the above range, the kinematic viscosity of the fuel oil composition of this embodiment at 50°C will be 3,000 mm². 2 / s or more 3.500mm 2 Since it becomes difficult to keep the flow rate below / s, combustion performance and environmental performance in reducing nitrogen oxide emissions will decrease, it may become difficult to fit various equipment such as pumps and flow meters into their operating range, and lubricity may decrease. By making it easier to keep the kinematic viscosity of the fuel oil composition of this embodiment within the above range at 50°C, combustion performance and environmental performance are improved, making it easier to adapt to the operating range of various equipment, and lubricity is improved, so preferably 2,800 mm. 2 / s or more, more preferably 2,900 mm 2 / s or more, more preferably 2,950 mm 2 The value is 1 / s or more, and preferably has an upper limit of 3,400 mm. 2 / s or less, more preferably 3,300 mm 2 / s or less, more preferably 3,200 mm 2 It is less than or equal to / s.

[0062] (b2) Sulfur content The sulfur content of the cracked diesel fraction is 0.400% by mass or less. If the sulfur content is outside the above range, it becomes difficult to keep the sulfur content of the fuel oil composition of this embodiment at 0.300% by mass or less, which may make it difficult to suppress corrosion and potentially degrade environmental performance. In order to suppress corrosion and improve environmental performance by making it easier to keep the sulfur content of the fuel oil composition of this embodiment at 0.300% by mass or less, the sulfur content of the cracked diesel fraction is preferably 0.300% by mass or less, more preferably 0.280% by mass or less, and the lower limit is preferable as much as possible. There are no particular restrictions, but it is usually 0.05% by mass or more.

[0063] (b3) Aromatic content The aromatic content of the cracked diesel fraction is 50.0% by volume or more. Here, the aromatic content refers to the total content of mono-ring aromatics, bi-ring aromatics, and three-ring or more aromatics. If the aromatic content is not within the above range, it may not be possible to suppress the blockage of the fuel oil filter due to sludge generation, which may lead to a decrease in normal fuel flow performance and a decrease in combustion performance. From the viewpoint of improving normal fuel flow performance and combustion performance by further suppressing blockage of the fuel oil filter due to sludge generation, the volume is preferably 60.0% or more, more preferably 65.0% or more, with no particular upper limit, and is usually 85.0% or less.

[0064] (b4) Aromatic content with 3 or more rings The content of aromatic compounds with three or more rings in the cracked diesel fraction is 10.0% by volume or more. If the content of aromatic compounds with three or more rings is not within the above range, it becomes difficult to achieve a content of 6.0% by volume or more for the fuel oil composition of this embodiment, which may reduce storage stability. From the viewpoint of improving storage stability, the content of aromatic compounds with three or more rings in the fuel oil composition of this embodiment is preferably 11.0% by volume or more, more preferably 11.5% by volume or more, and even more preferably 12.0% by volume or more. There is no particular upper limit, and it is usually 18.0% by volume or less.

[0065] The cracked diesel fraction has the properties and composition described above (b1) to (b4), and further, the following (b5) to (b 14 It is preferable that at least one of the properties and composition of the following be satisfied, and the following (b5)~(b 14 It is more preferable that both the properties and composition of the product are satisfied.

[0066] (b5) Density at 15℃ The density of the cracked diesel fraction at 15°C is preferably 0.9100 g / cm³. 3 More preferably 0.9200 g / cm³ 3 More preferably 0.925 g / cm³ 3 The above applies, with a preferred upper limit of 0.9500 g / cm³. 3 More preferably, 0.9400 g / cm³ 3 The following applies: If the density at 15°C is within the above range, the density of the fuel oil composition of this embodiment at 15°C is 0.8950 g / cm³. 3 This makes it easier to achieve the above, resulting in improved combustion performance, fuel efficiency, and storage stability.

[0067] (b6) Flash point From the viewpoint of improving handling safety, the flash point of the decomposed diesel fuel fraction is preferably 60.0°C or higher, more preferably 65.0°C or higher, and even more preferably 70.0°C or higher. There is no particular upper limit on the flash point, and it is usually 100°C or lower.

[0068] (b7) Residual carbon content of 10% residual oil The residual carbon content of the 10% residue of the cracked diesel fraction is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and preferably 0.20% by mass or less as an upper limit. When the residual carbon content of the 10% residue is within the above range, it becomes easier to set the residual carbon content of the 10% residue of the fuel oil composition of this embodiment to 0.21% by mass or more and 0.60% by mass or less, thereby improving combustion performance and storage stability. It also becomes easier to enjoy tax benefits.

[0069] (b8) Cetane number The cetane number of the cracked diesel fraction is preferably 20.0 or higher, more preferably 21.0 or higher, with no particular upper limit, and is usually 45.0 or lower. When the cetane number is within the above range, it becomes easier to achieve a cetane number of 31.0 or higher in the fuel oil composition of this embodiment, thereby improving combustion performance.

[0070] (b9) Moisture content The moisture content of the cracked diesel fraction is preferably 0.10% by volume or less, and more preferably less than 0.10% by volume. There is no particular lower limit, as a smaller limit is preferable. When the moisture content is within the above range, sludge formation and ice formation are suppressed, reducing the frequency of blockages and thus improving storage stability.

[0071] (b 10 ) Copper plate corrosion The copper plate corrosion of the decomposed diesel fraction is preferably 1 or less (1a or 1b) in terms of the copper plate classification for copper plate evaluation, and more preferably 1a. If the copper plate corrosion is 1 or less, corrosion of various auxiliary equipment can be prevented, thus enabling more stable operation of various equipment such as internal combustion engines and external combustion engines.

[0072] (b 11 ) Acid value The acid value of the cracked light oil fraction is preferably 0.10 mgKOH / g or less, and more preferably less than 0.10 mgKOH / g. The lower the acid value, the better, and there is no particular lower limit, but it is particularly preferably 0.0 mgKOH / g. When the acid value is within the above range, storage stability is improved and corrosion of components can be suppressed.

[0073] (b 12 ) Pour point The pour point of the cracked diesel fraction is preferably -5.0°C or lower, more preferably -7.5°C or lower. There is no particular lower limit, but it is usually -35.0°C or higher. When the pour point is within the above range, fluidity in storage tanks and piping at low temperatures is improved, and handling is also improved.

[0074] (b 13 )Nitrogen content The nitrogen content of the cracked diesel fraction is preferably 500 ppm by mass or less, more preferably 400 ppm by mass or less, and even more preferably 300 ppm by mass or less. There is no particular lower limit, but it is usually 50 ppm by mass or more. When the nitrogen content is within the above range, nitrogen oxides (NOx) are produced. X This reduces emissions, thus improving environmental performance.

[0075] (b 14 ) Distillation properties As for the distillation properties of the cracked light oil fraction, the 10% by volume distillation temperature is preferably 190.0°C or higher, more preferably 200.0°C or higher, and even more preferably 225.0°C or higher, with an upper limit of preferably 250.0°C or lower, and more preferably 245.0°C or lower. The 50% by volume distillation temperature is preferably 250.0°C or higher, more preferably 260.0°C or higher, and even more preferably 270.0°C or higher, with an upper limit of preferably 310.0°C or lower, more preferably 300.0°C or lower, and even more preferably 285.0°C or lower. Furthermore, the 90% by volume distillation temperature is preferably 310.0°C or higher, more preferably 320.0°C or higher, even more preferably 330.0°C or higher, with an upper limit of preferably 370.0°C or lower, more preferably 360.0°C or lower, and even more preferably 350.0°C or lower. When the distillation properties of the cracked diesel fraction are at the above-mentioned 10% volume distillation temperatures, 50% volume distillation temperatures, and 90% volume distillation temperatures, the effects of low-boiling-point and high-boiling-point components are suppressed, and combustion performance is improved. In this specification, the 10% volume distillation temperature, 50% volume distillation temperature, and 90% volume distillation temperature of the distillation properties are values ​​measured in accordance with JIS K2254:2018 (Petroleum products - Method for determining distillation properties - (Atmospheric pressure method)).

[0076] (Content of cracked diesel fraction) The content of cracked diesel fraction on a total composition basis is greater than 40.0% by volume and less than or equal to 60.0% by volume. If the content of cracked diesel fraction is 40.0% by volume or less, fuel efficiency and storage stability will decrease, and if it exceeds 60.0% by volume, combustion performance will decrease. From the viewpoint of improving combustion performance, fuel efficiency, and storage stability, the content of cracked diesel fraction on a total composition basis is preferably 42.5% by volume or more, more preferably 45.0% by volume or more, and as an upper limit, preferably 57.5% by volume or less, more preferably 55.0% by volume or less.

[0077] (Other diesel and kerosene fractions) The fuel oil composition of this embodiment may also contain, in addition to the cracked diesel fraction mentioned above, diesel fractions such as straight-run diesel fraction, straight-run diesel fraction, vacuum-fired diesel fraction, desulfurized diesel fraction, and desulfurized cracked diesel fraction, as well as kerosene fractions such as straight-run kerosene fraction and desulfurized kerosene fraction. Among these diesel and kerosene fractions, the straight-run diesel fraction is preferred from the viewpoint of improving fuel efficiency, combustion performance, environmental performance by reducing nitrogen oxide emissions, and storage stability when combined with fatty acid alkyl esters and cracked diesel fractions. These diesel and kerosene fractions can be used individually or in combination of multiple types. • Direct desulfurization of diesel fraction (diesel fraction obtained by directly desulfurizing atmospheric distillation residue oil and / or vacuum distillation residue oil in a desulfurization unit) • Straight-run diesel fraction (diesel fraction obtained by atmospheric distillation of crude oil in an atmospheric distillation unit) • Reduced-pressure diesel fraction (diesel fraction obtained by reducing the pressure of distillation residual oil in a reduced-pressure distillation apparatus) • Desulfurized light oil fraction (light oil fraction obtained by desulfurizing straight-run light oil fraction and / or vacuum-fired light oil fraction) • Desulfurized cracked light oil fraction (light oil fraction obtained by desulfurizing catalytically cracked light oil fraction obtained by fluid catalytic cracking of atmospheric distillation residue oil and / or vacuum distillation residue oil) • Straight-run kerosene fraction (kerosene fraction obtained by atmospheric distillation of crude oil using an atmospheric distillation unit) • Desulfurized kerosene fraction (kerosene fraction obtained by desulfurizing straight-run kerosene fraction)

[0078] (Properties of other diesel and kerosene fractions) The other diesel and kerosene fractions that can be used in this embodiment preferably have the following properties. When the other diesel and kerosene fractions have the following properties, the combination with fatty acid alkyl esters and cracked diesel fractions can improve fuel efficiency, combustion performance, environmental performance by reducing nitrogen oxide emissions, and storage stability.

[0079] The kinematic viscosity at 50°C is preferably 3,100 mmHg. 2 / s or more, more preferably 3,800 mm 2 / s or more, preferably 5.000 mm or less as the upper limit 2 / s or less, more preferably 4.500 mm or less 2 / s or less. The sulfur content is preferably 1.000 mass% or less, more preferably 0.400 mass% or less, still more preferably 0.100 mass% or less. As the lower limit, the less the better, and usually it is 0.010 mass% or more. The aromatic content is preferably 30.0% by volume or more, more preferably 35.0% by volume or more, still more preferably 40.0% by volume or more. There is no particular limitation on the upper limit, and usually it is 65.0% by volume or less. The content of aromatic components with 3 or more rings is preferably 1.5% by volume or more, more preferably 1.8% by volume or more. There is no particular limitation on the upper limit, and usually it is 5.0% by volume or less. The density at 15 °C is preferably 0.8300 g / cm 3 or more, more preferably 0.8400 g / cm 3 or more, still more preferably 0.8500 g / cm 3 or more. The upper limit is preferably 0.8900 g / cm 3 or less, more preferably 0.8800 g / cm 3 or less. The flash point is preferably 60.0 °C or higher, more preferably 65.0 °C or higher. The residual carbon content of the 10% residual oil is preferably 0.01 mass% or more, and the upper limit is preferably 0.20 mass% or less. The cetane number is preferably 30.0 or more, more preferably 35.0 or more. There is no particular limitation on the upper limit, and usually it is 70.0 or less. The water content is preferably 0.10% by volume or less, more preferably less than 0.10% by volume. The copper strip corrosion is preferably 1 or less (1a or 1b) as the classification of the copper strip in the copper strip determination, and particularly preferably 1a. The acid value is preferably 0.05 mgKOH / g or less, and more preferably less than 0.05 mgKOH / g. The lower the acid value, the better. There is no particular lower limit, but it is especially preferably 0.0 mgKOH / g. The pour point is preferably -0.0°C or lower, more preferably -2.5°C or lower, and there is no particular lower limit, but it is usually -30.0°C or higher. The nitrogen content is preferably 500 ppm by mass or less, more preferably 300 ppm by mass or less, and there is no particular lower limit, but it is usually 50 ppm by mass or more. Regarding the distillation properties, the 10% by volume distillation temperature is preferably 170.0°C or higher, more preferably 180.0°C or higher, with an upper limit of preferably 270.0°C or lower, more preferably 260.0°C or lower. The 50% by volume distillation temperature is preferably 250.0°C or higher, more preferably 265.0°C or higher, with an upper limit of preferably 310.0°C or lower, more preferably 300.0°C or lower. Furthermore, the 90% by volume distillation temperature is preferably 310.0°C or higher, more preferably 330.0°C or higher, with an upper limit of preferably 370.0°C or lower, more preferably 355.0°C or lower.

[0080] (Content of other diesel and kerosene fractions) The content of other diesel and kerosene fractions on a total composition basis is preferably 5.0% by volume or more, more preferably 10.0% by volume or more, and even more preferably 12.5% ​​by volume or more, with an upper limit of preferably 45.0% by volume or less, more preferably 40.0% by volume or less, and even more preferably 35.0% by volume or less, from the viewpoint of improving fuel efficiency, combustion performance, environmental performance by reducing nitrogen oxide emissions, and storage stability, when combined with fatty acid alkyl esters and cracked diesel fractions.

[0081] (Other heavy oil fractions, etc. (residual carbon source)) In addition to the above cracked gas oil fraction, the fuel oil composition of this embodiment may also contain the following heavy oil fractions such as atmospheric distillation residue oil, vacuum distillation residue oil, straight-run heavy oil, and cracked heavy oil, as well as heavy oil fractions such as extract (the above fractions, etc. are also referred to as "residual carbon sources"). Among these heavy oil fractions, etc. (residual carbon sources), from the viewpoints of improving fuel consumption performance, combustion performance, environmental performance of reducing nitrogen oxide emissions, and further improving storage stability, when combined with fatty acid alkyl esters and cracked gas oil fractions, atmospheric distillation residue oil is preferred. These heavy oil fractions, etc. (residual carbon sources) can be used alone or in combination of multiple types. · Atmospheric distillation residue oil (residue oil obtained by subjecting crude oil to atmospheric distillation in an atmospheric distillation unit) · Vacuum distillation residue oil (residue oil obtained by subjecting atmospheric distillation residue oil to vacuum distillation in a vacuum distillation unit) · Straight-run heavy oil fraction (heavy oil obtained by directly desulfurizing atmospheric distillation residue oil and / or vacuum distillation residue oil in a direct desulfurization unit) · Cracked heavy oil fraction (heavy oil fraction obtained by fluid catalytic cracking of straight-run heavy oil) · Extract (medium and heavy vacuum distillation distillate oil obtained by subjecting atmospheric distillation residue oil to vacuum distillation, high-aromatic extract oil obtained by distillation separation of bright stock oil (desalted oil of vacuum distillation residue oil) with furfural, etc.)

[0082] (Properties of other heavy oil fractions, etc. (residual carbon sources)) The density at 15 °C is preferably 0.9850 g / cm 3 Hereinafter, more preferably 0.9750 g / cm 3 Hereinafter, 0.9600 g / cm 3 Hereinafter, and preferably 0.9100 g / cm or more as the lower limit 3 Hereinafter, more preferably 0.9300 g / cm or more 3 Hereinafter. The kinematic viscosity at 50 °C is preferably 200.000 mm 2 / s or less, more preferably 190.000 mm 2 / s or less, and there is no particular limitation as the lower limit, usually 30.000 mm 2 / s or more. The sulfur content is preferably 3,000% by mass or less, more preferably 2,750% by mass or less. There is no particular lower limit, as a smaller lower limit is preferable, and it is usually 0,500% by mass or more. The residual carbon content of the 10% residual oil is preferably 25.0% by mass or more, more preferably 40.0% by mass or more, and even more preferably 45.0% by mass or more, with an upper limit of preferably 100.0% by mass or less, and more preferably 70.0% by mass or less. The moisture content is preferably 0.1% by volume or less, and more preferably less than 0.1% by volume. In terms of copper plate corrosion, it is preferable that the copper plate classification in the copper plate assessment is 1 or less (1a or 1b), and of course, 1a is preferred. The residual carbon content is preferably 3.0% by mass or more, more preferably 5.0% by mass or more, with an upper limit of preferably 12.0% by mass or less, and more preferably 9.0% by mass or less. In this specification, the residual carbon content is a value measured in accordance with JIS K 2270-2:2009 (Crude oil and petroleum products - Method for determining residual carbon content - Part 2: Microscopic method).

[0083] (Content of other heavy oil fractions, etc. (residual carbon sources)) The content of other heavy oil fractions (residual carbon sources) on a total composition basis is preferably 0.01% by volume or more, more preferably 0.10% by volume or more, even more preferably 0.15% by volume or more, with an upper limit of preferably 1.00% by volume or less, more preferably 0.50% by volume or less, and even more preferably 0.30% by volume or less, from the viewpoint of improving fuel efficiency, combustion performance, environmental performance by reducing nitrogen oxide emissions, and storage stability in combination with fatty acid alkyl esters and cracked light oil fractions.

[0084] (Various additives) The fuel oil composition of this embodiment may contain various additives as needed, such as antioxidants, low-temperature fluidity improvers, lubricity improvers, cetane number improvers, combustion accelerators, detergents, sludge dispersants, and antifungal agents, within the limits of maintaining the above-mentioned properties. Coumarin may also be added from the standpoint of light oil excise tax.

[0085] (Application) The fuel oil composition of this embodiment is excellent in fuel efficiency and combustion performance, as well as in environmental performance that reduces nitrogen oxide emissions, and also in storage stability, making it suitable for use in both internal and external combustion engines. Considering its excellent performance in the combustion performance evaluation method using a hydraulic spray burner, it is more preferable to use it in an external combustion engine, and among those, it is more preferable to use it in an external combustion engine equipped with a hydraulic spray burner, and even more preferable to use it in an external combustion engine equipped with a hydraulic spray burner with a rated fuel capacity of 100 L / hour or less.

[0086] [Method for producing fuel oil composition] The fuel oil composition of this embodiment can be produced by mixing the above-mentioned fatty acid alkyl ester and cracked light oil fraction, and optionally the above-mentioned other light oil fractions, kerosene fractions, heavy oil fractions, etc. (residual carbon source) and various additives, such that the content of fatty acid alkyl ester and cracked light oil fraction on a basis of the total composition is 15.0% by volume or more and 35.0% by volume or less, and more than 40.0% by volume and 60.0% by volume or less, respectively.

[0087] There are no particular restrictions on the order in which fatty acid alkyl esters and cracked light oil fractions, and optionally other light oil fractions, kerosene fractions, heavy oil fractions, etc. (residual carbon sources), and various additives are blended. For example, fatty acid alkyl esters may be mixed with cracked light oil fractions, and optionally other light oil fractions, heavy oil fractions, etc. (residual carbon sources), and various additives in succession. Alternatively, fatty acid alkyl esters, cracked light oil fractions, and optionally other light oil fractions, heavy oil fractions, etc. (residual carbon sources), and various additives may be mixed simultaneously (all-at-once mixing). Alternatively, fatty acid alkyl esters and cracked light oil fractions may be mixed beforehand, and then optionally other light oil fractions, heavy oil fractions, etc. (residual carbon sources) and various additives may be mixed. Alternatively, fatty acid alkyl esters and cracked light oil fractions may be mixed beforehand, and then optionally other light oil fractions, heavy oil fractions, etc. (residual carbon sources) and various additives may be added and mixed in any order. [Examples]

[0088] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited in any way by these examples. The properties of each substrate were determined according to the method described above.

[0089] [Measurement of properties and composition] The properties and composition of the various base materials used in the examples and comparative examples—fatty acid alkyl esters, cracked light oil fractions, direct decontaminated light oil fractions, and atmospheric distillation residue oil—and the properties and composition of the fuel oil compositions in the examples and comparative examples were measured by the following methods. The properties and composition of the fatty acid alkyl esters are shown in Table 1, and the properties and composition of the other various base materials are shown in Table 2. The properties and composition of the fuel oil compositions are shown in Tables 3 to 6. (1)(a4)(b5) Density at 15℃: Measured in accordance with JIS K 2249-1:2011 (Crude oil and petroleum products - Method for determining density - Part 1: Vibration method). (2)(a5)(b1) Kinematic viscosity at 50°C: Measured in accordance with JIS K 2283:2000 (Test method for kinematic viscosity of crude oil and petroleum products). (3)(a6)(b2) Sulfur content: The sulfur content of fuel oil composition, cracked diesel fraction, direct decontaminated diesel fraction, and atmospheric distillation residue oil is measured in accordance with JIS K 2541-4:2003 (Crude oil and petroleum products - Sulfur content test method - Part 4: Radiation excitation method), and the sulfur content of fatty acid alkyl esters is measured in accordance with JIS K 2541-6:2013 (Crude oil and petroleum products - Sulfur content test method - Part 6: Ultraviolet fluorescence method). • (4)(b3)(b4) Aromatic content (mono-ring aromatics, bi-ring aromatics, and tri-ring or more aromatics): Measured by High Performance Liquid Chromatography (HQChromatography) as specified in JPI-5S-49-2007, Petroleum Products - Hydrocarbon Type Test Methods. • (5)(a3)(b7) Residual carbon content of 10% residual oil: This value is measured using 10% residual oil prepared in accordance with Annex A, in accordance with JIS K 2270-2:2009 (Crude oil and petroleum products - Method for determining residual carbon content - Part 2: Microscopic method). The residual carbon content is also measured in accordance with JIS K 2270-2:2009 (Crude oil and petroleum products - Method for determining residual carbon content - Part 2: Microscopic method). (6)(a1)(b8) Cetane number: This is a value measured in accordance with JIS K 2280-4:2013 (Petroleum products - Method for determining octane number, cetane number and cetane index - Part 4: Cetane number). (7)(a7)(b6) Flash point: The flash points of the fuel oil composition, cracked light oil fraction, direct decontaminated light oil fraction, and atmospheric distillation residue oil were measured in accordance with JIS K 2265-3:2007 (Crude oil and petroleum products - Flash point test method - Part 3: Pennsky-Haltens closed method), and the flash points of fatty acid alkyl esters were measured in accordance with JIS K 2265-2:2007 (Crude oil and petroleum products - Flash point test method - Part 2: Rapid equilibrium closed method). (8)(a8)(b9) Moisture content: The moisture content of fuel oil composition, cracked light oil fraction, direct decontaminated light oil fraction, and atmospheric distillation residue oil was measured in accordance with JIS K 2275-1:2015 (Crude oil and petroleum products - Method for determining moisture content - Part 1: Distillation method), and the moisture content of fatty acid alkyl esters was measured in accordance with JIS K 2275-3:2015 (Crude oil and petroleum products - Method for determining moisture content - Part 3: Karl Fischer coulometric titration method). ·(9)(a9)(b 10 Copper plate corrosion: Measured in accordance with JIS K 2513:2000 (Petroleum products - Copper plate corrosion test method). The test temperature was 50°C and the test time was 3 hours. (10)(a2)(b 11 Acid value: Measured in accordance with JIS K 2501:2003 (Petroleum products and lubricating oils - Neutralization value test method). (11)(a 10 )(b 12 Pour point: Measured in accordance with JIS K2269:1987 (Test method for pour point and cloud point of crude oil and petroleum products). (12)(b 13 Nitrogen content: Measured in accordance with JIS K 2609:1998 (Crude oil and petroleum products - Test method for nitrogen content). (13) Total heat output: Measured according to the method described in "1. Fuel efficiency" below. (a 11 ) Composition analysis of fatty acid alkyl esters: The composition was measured by gas chromatography analysis using a flame ionization detector (FID) in accordance with the Standard Method for Analysis of Fats and Oils (established by the Japan Oil Chemists' Society in 1993), "2.4.21.3-77 Fatty Acid Composition (FID Temperature-Increased Gas Chromatography Method)". ·(b 14 Distillation properties (at 10% volume distillation temperature, 50% volume distillation temperature, and 90% volume distillation temperature): Measured in accordance with JIS K2254:2018 (Petroleum products - Method for determining distillation properties - (Atmospheric pressure method)).

[0090] [Performance evaluation criteria] Each of the following performance aspects (1-4) was evaluated, and the worst evaluation was used as the overall evaluation. A C rating indicates failure. The evaluations for each performance aspect are shown in Tables 3 and 4.

[0091] 1. Fuel efficiency For the fuel oil compositions of the examples and comparative examples, the "Gross heat of combustion," measured according to the test method specified in "Standard Test Method for Heat of Combustion of Liquid Hydrocarbon Fuels by Bomb Calorimeter" (ASTM D240-9), was multiplied by the density to convert the value to a per-volume value, which was then used as the total calorific value (MJ / L) and evaluated according to the following criteria. A: It was 38.9 MJ / L or higher. B: It was between 38.7 MJ / L and less than 38.9 MJ / L. C: was less than 38.7 MJ / L.

[0092] 2. Combustion performance The fuel oil compositions of the examples and comparative examples were evaluated as follows. (1) Test machine and setting conditions The "House Kaonki HK2027TCV1 (model)" (rated fuel capacity: 6.3 L / h, on / off control, manufactured by Nepon Corporation) was used as the test unit. • Fuel spray pressure: 1.03 MPa (hydraulic spray burner) • Band shutter opening: Adjusts the oxygen concentration in the exhaust gas to 2.8 ± 0.2%. • Fuel heating burner front heater: Off • Evaluation room temperature: 29~34℃ • Sample oil temperature: 25-30°C (2) Evaluation items After performing a 20-minute continuous burn under the same conditions, the following items were evaluated. (Ignitability) There should be no visible delay in ignition during the ignition process. (Combustibility; measurement of soot concentration) An exhaust gas sampling port was attached to the flue closest to the boiler body (the combustion chamber portion of the "House Kaonki" mentioned above), and the soot concentration (Baccarat Smoke Number (SN)) in the combustion exhaust gas was measured using a Baccarat Smoke Tester, based on the test method specified in "Standard Test Method for Smoke Density in Fuel Gases from Burning Distillate Fules" (ASTM D2156-09). (3) Evaluation Criteria The evaluation items in (2) above were evaluated according to the following criteria. A: There was no ignition delay, and the soot concentration (SN) was 1.0 or less. B: There was no ignition delay, and the soot concentration (SN) was greater than 1.0 and less than or equal to 2.0. C: The result was different from A and B above.

[0093] 3. Environmental performance (nitrogen oxides (NOx) X (Reduction performance) (1) Test machine and setting conditions The same conditions as those described in "2. Combustion Performance" (1) above were used for the test equipment and settings. (2) Evaluation items In addition to performing the (combustibility; measurement of soot concentration) evaluation item in "2. Combustion Performance" (2) above, the oxygen concentration and nitrogen oxides (NOx) in the combustion exhaust gas are also measured. X The concentration was measured using a combustion flue gas analyzer ("HT-1300Z (model number)", manufactured by Hodaka Corporation). Based on the measured results, the value converted to an oxygen concentration of 0% using the following formula is used to determine nitrogen oxides (NOx). X ) was defined as the concentration. Nitrogen oxide concentration (volume ppm) = C NOx (capacity ppm)×21 / (21-C O ) C NOx : Nitrogen oxides (NO X ) Concentration measurement value (volume ppm) C O Oxygen concentration measurement value (volume %) (3) Evaluation Criteria The evaluation items in (2) above were evaluated according to the following criteria. A: The nitrogen oxide concentration was 80 ppm by volume or less. B: The nitrogen oxide concentration was greater than 80 ppm by volume and less than or equal to 90 ppm by volume. C: The nitrogen oxide concentration was over 90 ppm by volume.

[0094] 4. Storage stability performance A 4L tin can (made of tin) with an opening (φ32.5mm) at the top to allow air circulation was used to store 1L of the fuel oil composition of the example and comparative example in a dark place at room temperature (no temperature control by air conditioning was performed, and the room temperature during the period was 20-32°C). The amount of dry sludge contained in the fuel oil composition after storage was measured according to the dry sludge measurement method of the Japan Fisheries Cooperative Association (ZGS T-1010). The amount of dry sludge was evaluated according to the following criteria. A: The amount of dry sludge was 1.0 mg / 100 mL or less. B: The amount of dry sludge was greater than 1.0 mg / 100 mL and less than or equal to 2.0 mg / 100 mL. C: The amount of dry sludge was greater than 2.0 mg / 100 mL.

[0095] [Examples 1-4 and Comparative Examples 1-14] Various base materials having the properties and compositions shown in Tables 1 and 2 were mixed in the proportions shown in Tables 3 to 6 to prepare fuel oil compositions for Examples 1 to 4 and Comparative Examples 1 to 14. For each of the obtained fuel oil compositions, the combustion performance and storage stability were evaluated using the method described above. The results are shown in Tables 3 to 6.

[0096] [Table 1] *1, Both base material 1 (fatty acid alkyl ester 1) and base material 2 (fatty acid alkyl ester 2) are fatty acid methyl esters obtained using waste cooking oil containing rapeseed oil.

[0097] [Table 2]

[0098] [Table 3]

[0099] [Table 4]

[0100] [Table 5]

[0101] [Table 6]

[0102] [Performance evaluation results] As shown in Table 3, the fuel oil composition of this embodiment was found to be suitable for internal and external combustion engines, as it exhibited good fuel efficiency, combustion performance, environmental performance, and storage stability. Furthermore, due to its excellent combustion performance with hydraulic spray burners, it was found to be particularly suitable for external combustion engines equipped with hydraulic spray burners, especially those with a rated combustion volume of 100 L / hour or less. External combustion engines equipped with hydraulic spray burners have nitrogen oxides (NOx) in their combustion exhaust gases. X Installing denitrification equipment to reduce nitrogen oxides (NOx) is difficult from a cost standpoint. The fuel oil composition of this embodiment is nitrogen oxide (NOx). X Even considering its excellent environmental performance in reducing emissions, it can be particularly suitable for use in external combustion engines equipped with the above-mentioned hydraulic spray burner. Furthermore, the sulfur content in the fuel oil composition of this embodiment is 0.140 to 0.160% by mass, which is extremely low at 0.300% by mass or less. This makes it possible to prevent corrosion caused by an increase in sulfur oxides in exhaust gas and to prevent an increase in environmental burden. Therefore, the fuel oil composition of this embodiment contains nitrogen oxides (NOx). XIt was confirmed that this product has extremely excellent environmental performance, as it can reduce not only emissions of ) but also emissions of sulfur oxides.

[0103] On the other hand, the fuel oil compositions of Comparative Examples 1 and 2, which contained specific fatty acid alkyl ester 1 but in small amounts, were inferior in terms of combustion performance, and the fuel oil composition of Comparative Example 3, which contained a large amount, was inferior in terms of storage stability performance. The fuel oil compositions of Comparative Examples 4 and 5, which did not contain specific fatty acid alkyl ester 1 but contained fatty acid alkyl ester 2 with a low residual carbon content in the 10% residual oil, were both found to be inferior in terms of storage stability performance. Regarding the cracked diesel fraction, the fuel oil compositions of Comparative Examples 6 and 8-10, in which the cracked diesel fraction content was reduced and the direct decomposition diesel fraction was increased accordingly, were found to be inferior in terms of fuel efficiency and storage stability, while the fuel oil composition of Comparative Example 7, which had a high content of cracked diesel fraction, was found to be inferior in terms of combustion performance. Furthermore, the fuel oil compositions of Comparative Examples 11-14, in which the cracked diesel fraction content was reduced and the cracked diesel fraction with lower kinematic viscosity was increased accordingly, were found to be inferior in terms of environmental performance. [Industrial applicability]

[0104] The fuel oil composition of this embodiment contains fatty acid alkyl esters and cracked light oil fractions in predetermined amounts, resulting in a composition that is excellent in fuel efficiency and combustion performance, as well as environmental performance that reduces nitrogen oxide emissions, and also has excellent storage stability. It can be suitably used in internal combustion engines and external combustion engines, especially external combustion engines equipped with hydraulic spray burners.

Claims

1. (a) １ ) ~ (a ３ ) an alkyl fatty acid ester that satisfies all of the following conditions and (b １ ) ~ (b ４ A fuel oil composition that satisfies all of the following (1) to (6): a cracked diesel fraction that satisfies all of the following conditions, wherein the fatty acid alkyl ester is an ester of a fatty acid having 8 to 22 carbon atoms and an alkyl alcohol having 1 to 4 carbon atoms, the content of the fatty acid alkyl ester on a basis of the total composition is 15.0% by volume or more and 35.0% by volume or less, and the content of the cracked diesel fraction on a basis of the total composition is more than 40.0% by volume and 60.0% by volume or less. (a １ ) Cetane number of 49.0 or higher (a ２ ) Acid value is 0.50 mg KOH / g or less (a ３ ) The residual carbon content of the 10% residual oil is 0.80% by mass or more and 1.50% by mass or less. (b １ ) The kinematic viscosity at 50 °C is 2.600 mm ２ / s or more and 3.600 mm ２ / s or less (b) ２ ) Sulfur content is less than 0.400 mass% (b ３ ) Aromatic content of 50.0% by volume or more (b ４ ) Aromatic content of three or more rings is 10.0% by volume or more. (1) Density at 15°C is 0.8950 g / cm³ ３ That's all. (2) The kinematic viscosity at 50°C is 3,000 mm². ２ / s or more 3.500mm ２ / s or less (3) Sulfur content is 0.300% by mass or less (4) The content of aromatic compounds with three or more rings is 6.0% by volume or more. (5) The residual carbon content of the 10% residual oil is 0.21% by mass or more and 0.60% by mass or less. (6) Cetane number of 31.0 or higher

2. The fuel oil composition according to claim 1, wherein the fatty acid alkyl ester is a fatty acid methyl ester.

3. The fuel oil composition according to claim 1 or 2, wherein the fatty acid is a mixed fatty acid containing two or more fatty acids having 8 or more carbon atoms and 22 or fewer carbon atoms.

4. The fuel oil composition according to claim 3, wherein the mixed fatty acid is obtained from at least one raw material selected from animal oils and vegetable oils.

5. A fuel oil composition according to claim 1 or 2, used in an external combustion engine.

6. The fuel oil composition according to claim 5, wherein the external combustion engine is equipped with a hydraulic spray burner with a rated combustion capacity of 100 L / hour or less.

7. An ester of a fatty acid having 8 to 22 carbon atoms and an alkyl alcohol having 1 to 4 carbon atoms, as follows (a １ ) ~ (a ３ ) an alkyl fatty acid ester that satisfies all of the following conditions and (b １ ) ~ (b ４ A method for producing a fuel oil composition that satisfies all of the following (1) to (6): mixing a cracked light oil fraction that satisfies all of the following conditions with the fatty acid alkyl ester such that the content of the cracked light oil fraction on a basis of the total composition is 15.0% by volume or more and 35.0% by volume or less, and the content of the cracked light oil fraction on a basis of the total composition is more than 40.0% by volume and 60.0% by volume or less. (a １ ) Cetane number of 49.0 or higher (a ２ ) Acid value is 0.50 mg KOH / g or less (a ３ ) The residual carbon content of the 10% residual oil is 0.80% by mass or more and 1.50% by mass or less. (b １ ) The kinematic viscosity at 50°C is 2,600 mm ２ / s or more 3.600mm ２ / s or less (b) ２ ) Sulfur content is less than 0.400 mass% (b ３ ) Aromatic content of 50.0% by volume or more (b ４ ) Aromatic content of three or more rings is 10.0% by volume or more. (1) Density at 15°C is 0.8950 g / cm³ ３ That's all. (2) The kinematic viscosity at 50°C is 3,000 mm². ２ / s or more 3.500mm ２ / s or less (3) Sulfur content is 0.300% by mass or less (4) The content of aromatic compounds with three or more rings is 6.0% by volume or more. (5) The residual carbon content of the 10% residual oil is 0.21% by mass or more and 0.60% by mass or less. (6) Cetane number of 31.0 or higher

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