Fuel composition for lean-burn engines

Abstract

To provide a fuel composition for a lean-burn engine capable of enlarging lean limit of the lean-burn engine.SOLUTION: A fuel composition for a lean-burn engine has a content of hydrocarbons having 7 and 8 carbon atoms of 25 vol.% or more based on a total amount of the fuel composition.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to fuel compositions for lean-burn engines. [Background technology]

[0002] Lean-burn engines that burn fuel with a mixture leaner than the stoichiometric air-fuel ratio have been known. For example, Patent Document 1 discloses a fuel composition for lean-burn engines that contains one or more gasolines selected from the group consisting of alkylate gasoline, catalytically reformed gasoline, light catalytic cracked gasoline, and cokerite gasoline. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-182579 Summary of the Invention [Problem to be solved by the invention]

[0004] In a lean-burn engine, the upper limit of the air-fuel ratio (air / fuel) at which stable operation is possible is called the lean limit, and by expanding this lean limit, improvements in fuel economy and stable combustion are expected.

[0005] Therefore, one aspect of the present invention aims to provide a fuel composition for a lean-burn engine that can extend the lean limit of the lean-burn engine. [Means for solving the problem]

[0006] One aspect of the present invention relates to a fuel composition for lean-burn engines, in which the content of hydrocarbons having 7 and 8 carbon atoms is 25% by volume or more, based on the total volume of the fuel composition.

[0007] In one embodiment, the content of isoparaffins having 7 and 8 carbon atoms contained in the fuel composition for lean burn engines may be 6% by volume or more based on the total volume of the fuel composition.

[0008] In one embodiment, the 50% by volume distillation temperature (T50) of the lean burn engine fuel oil composition may be 50°C or higher. [Effects of the Invention]

[0009] According to one aspect of the present invention, there is provided a fuel composition for a lean-burn engine that is capable of extending the lean limit of a lean-burn engine. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present invention will be described in detail below.

[0011] The fuel composition of this embodiment has a content of hydrocarbons with 7 and 8 carbon atoms (the total content of hydrocarbons with 7 carbon atoms and hydrocarbons with 8 carbon atoms) of 25% by volume or more, based on the total volume of the fuel composition.

[0012] In the fuel composition of this embodiment, the lean limit can be expanded by containing 25% by volume or more of hydrocarbons having 7 and 8 carbon atoms. Therefore, the fuel composition of this embodiment can be suitably used as a fuel composition for lean-burn engines (particularly for ultra-lean combustion engines with a lean limit of 2 or more). Furthermore, in the fuel composition of this embodiment, the net thermal efficiency is improved by containing 25% by volume or more of hydrocarbons having 7 and 8 carbon atoms.

[0013] In this specification, the content of each component in the fuel composition refers to the value measured by the method described in JIS K 2536-2 "Petroleum products - Testing methods for components, Part 2: Determination of total components by gas chromatography."

[0014] In the fuel composition of this embodiment, the content of hydrocarbons having 7 and 8 carbon atoms is preferably 30% by volume or more, and may be 35% by volume or more, 40% by volume or more, 45% by volume or more, or 50% by volume or more, since this improves the calorific value per volume. The content of hydrocarbons having 7 and 8 carbon atoms is preferably 80% by volume or less, 75% by volume or less, 70% by volume or less, 65% by volume or less, 60% by volume or less, or 55% by volume or less, since this further improves the lean limit.

[0015] The hydrocarbons having 7 and 8 carbon atoms may contain, for example, one or more of paraffins (normal paraffins and isoparaffins), olefins, aromatic compounds, and the like.

[0016] In the fuel composition of this embodiment, the content of isoparaffins having 7 and 8 carbon atoms is preferably 6% by volume or more, and may be 8% by volume or more, 10% by volume or more, 12% by volume or more, 15% by volume or more, or 20% by volume or more, based on the total amount of the fuel composition, in order to improve knock resistance. The content of isoparaffins having 7 and 8 carbon atoms may be preferably 50% by volume or less, 45% by volume or less, 40% by volume or less, 35% by volume or less, 30% by volume or less, or 25% by volume or less, in order to further improve the lean limit.

[0017] The proportion of paraffins having 7 and 8 carbon atoms in the hydrocarbons having 7 and 8 carbon atoms may be, for example, 10% by volume or more, preferably 15% by volume or more, and more preferably 20% by volume or more. The proportion of paraffins having 7 and 8 carbon atoms in the hydrocarbons having 7 and 8 carbon atoms may be, for example, 35% by volume or less, preferably 30% by volume or less, and more preferably 25% by volume or less.

[0018] From the viewpoint of improving knock resistance, the proportion of normal paraffins having 7 and 8 carbon atoms in the hydrocarbons having 7 and 8 carbon atoms may be, for example, 3% by volume or less, preferably 2% by volume or less, and more preferably 0% by volume.

[0019] The proportion of isoparaffins having 7 and 8 carbon atoms in the hydrocarbons having 7 and 8 carbon atoms is preferably 6% by volume or more, and may be 8% by volume or more, 10% by volume or more, 12% by volume or more, 15% by volume or more, or 20% by volume or more, since this improves knock resistance. Furthermore, the proportion of isoparaffins having 7 and 8 carbon atoms in the hydrocarbons having 7 and 8 carbon atoms may be, for example, 32% by volume or less, preferably 28% by volume or less, and more preferably 25% by volume or less.

[0020] The proportion of olefins having 7 and 8 carbon atoms in hydrocarbons having 7 and 8 carbon atoms may be, for example, 8% by volume or more, preferably 12% by volume or more, more preferably 15% by volume or more, and even more preferably 20% by volume or more, since this improves the lean limit. Also, the proportion of olefins having 7 and 8 carbon atoms in hydrocarbons having 7 and 8 carbon atoms may be, for example, 100% by volume or less, preferably 80% by volume or less, more preferably 60% by volume or less, and even more preferably 40% by volume or less.

[0021] From the viewpoint of further improving the lean limit, the proportion of naphthenes having 7 and 8 carbon atoms in the hydrocarbons having 7 and 8 carbon atoms may be, for example, 10% by volume or less, preferably 8% by volume or less, more preferably 5% by volume or less, and even more preferably 1% by volume or less.

[0022] From the viewpoint of further improving the lean limit, the proportion of aromatic compounds having 7 and 8 carbon atoms in hydrocarbons having 7 and 8 carbon atoms may be, for example, 10% by volume or less, preferably 5% by volume or less, more preferably 2% by volume or less, and even more preferably 1% by volume or less.

[0023] The fuel composition of this embodiment may further contain hydrocarbons having 4 to 6 carbon atoms. From the viewpoint of further improving the lean limit, the content of the hydrocarbons having 4 to 6 carbon atoms may be, for example, 100% by volume or less, preferably 80% by volume or less, more preferably 60% by volume or less, and even more preferably 40% by volume or less, based on the total amount of the fuel composition.

[0024] Hydrocarbons having 4 to 6 carbon atoms may include, for example, paraffins having 4 to 6 carbon atoms (paraffins having 4 to 6 carbon atoms and isoparaffins having 4 to 6 carbon atoms), olefins having 4 to 6 carbon atoms, aromatic compounds having 6 carbon atoms (benzene), and the like.

[0025] The fuel composition of this embodiment may further contain hydrocarbons having 9 or more carbon atoms. From the viewpoint of further improving the calorific value per volume, the content of hydrocarbons having 9 or more carbon atoms may be, for example, 0.5% by volume or more, preferably 1% by volume or more, more preferably 2% by volume or more, and even more preferably 3% by volume or more, based on the total amount of the fuel composition. Furthermore, the content of hydrocarbons having 9 or more carbon atoms may be, for example, 40% by volume or less, 30% by volume or less, 20% by volume or less, or 10% by volume or less, based on the total amount of the fuel composition.

[0026] Hydrocarbons having 9 or more carbon atoms may include, for example, paraffins having 9 or more carbon atoms (paraffins having 9 or more carbon atoms and isoparaffins having 9 or more carbon atoms), olefins having 9 or more carbon atoms, aromatic compounds having 9 or more carbon atoms, etc.

[0027] The aromatic content of the fuel composition of this embodiment may be, for example, 0.1% by volume or more, preferably 0.5% by volume or more, and more preferably 1% by volume or more, from the viewpoint of maintaining the calorific value per volume. Also, the aromatic content of the fuel composition of this embodiment may be, for example, 10% by volume or less, preferably 8% by volume or less, and more preferably 6% by volume or less, from the viewpoint of further improving the lean limit.

[0028] The fuel composition of this embodiment may further contain an oxygen-containing compound.

[0029] The oxygen-containing compound is an organic compound containing oxygen as a constituent element. Examples of the oxygen-containing compound include an oxygen-containing heterocyclic compound, an oxygen-containing aromatic compound, and an oxygen-containing aliphatic compound. The oxygen-containing compound may be used alone or in combination of two or more.

[0030] The oxygen-containing heterocyclic compound is a compound having an oxygen-containing heterocycle. Examples of the oxygen-containing heterocyclic compound include compounds having an oxygen-containing heterocycle such as a furan ring, a tetrahydrofuran ring, an ethylene oxide ring, a propylene oxide ring, a pyran ring, a tetrahydropyran ring, a benzofuran ring, and a benzopyran ring. As the oxygen-containing heterocyclic compound, a compound having a furan ring is preferred from the viewpoint of obtaining the above-mentioned effects more significantly. Examples of the compound having a furan ring include furan, 2-methylfuran, and 2,5-dimethylfuran. As the compound having a furan ring, furan and 2-methylfuran are particularly preferred.

[0031] An oxygen-containing aromatic compound is a compound containing oxygen as a constituent element and having an aromatic ring. Examples of the oxygen-containing aromatic compound include aromatic compounds having an oxygen atom directly bonded to the aromatic ring (e.g., alkoxybenzenes, phenols, etc.). Examples of the alkoxybenzene include anisole, phenetole, and propyloxybenzene. As the alkoxybenzene, anisole and phenetole are preferred from the viewpoint of the boiling point range.

[0032] Examples of oxygen-containing aliphatic compounds include alcohols and ethers (such as ethanol, isobutyl alcohol, and ETBE (ethyl tert-butyl ether)).

[0033] The oxygen-containing compound is preferably ethanol.

[0034] In the fuel composition of this embodiment, the content of the oxygen-containing compound may be, for example, 50% by volume or less, preferably 45% by volume or less, more preferably 40% by volume or less, and even more preferably 35% by volume or less, based on the total volume of the fuel composition. Furthermore, when the fuel composition of this embodiment contains an oxygen-containing compound, the content thereof may be, for example, 3% by volume or more, 5% by volume or more, or 10% by volume or more, based on the total volume of the fuel composition.

[0035] The fuel composition of this embodiment may further contain other components in addition to those described above. Examples of such other components include detergents and dispersants, antioxidants, metal deactivators, surface ignition inhibitors, anti-icing agents, combustion improvers, antistatic agents, colorants, rust inhibitors, water removal agents, discriminating agents, odorants, and friction modifiers. The total content of these other components may be, for example, 1% by volume or less, preferably 0.5% by volume or less, and more preferably 0.1% by volume or less, based on the total amount of the fuel composition. The total content of the above other components may be, for example, 0.001% by volume or more, or 0.002% by volume or more, based on the total amount of the fuel composition.

[0036] As the detergent-dispersant, a commonly used detergent-dispersant can be used, for example, compounds known as gasoline detergent-dispersants, such as succinimide, polyalkylamine, and polyetheramine. Examples of antioxidants include N,N'-diisopropyl-p-phenylenediamine, N,N'-diisobutyl-p-phenylenediamine, 2,6-di-t-butyl-4-methylphenol, and hindered phenols. Examples of metal deactivators include amine carbonyl condensation compounds such as N,N'-disalicylidene-1,2-diaminopropane. Examples of surface ignition inhibitors include organic phosphorus compounds. Examples of anti-icing agents include polyhydric alcohols or their ethers. Examples of combustion improvers include alkali metal salts or alkaline earth metal salts of organic acids, and higher alcohol sulfates. Examples of antistatic agents include anionic surfactants, cationic surfactants, and amphoteric surfactants. Examples of colorants include azo dyes. Examples of rust inhibitors include organic carboxylic acids or derivatives thereof, alkenyl succinic acid esters, etc. Examples of water-removing agents include sorbitan esters, etc. Examples of discriminating agents include chryzanin and coumarin, etc. Examples of odorants include natural essential oil synthetic fragrances, etc. Examples of friction modifiers include mixtures of higher carboxylic acid monoglycerides and higher carboxylic acid amide compounds, etc.

[0037] The initial boiling point of the fuel composition of this embodiment may be 10°C or higher, 15°C or higher, or 20°C or higher, and may be 45°C or lower, 40°C or lower, or 35°C or lower. The 5% by volume outlet temperature (T5) of the fuel composition of this embodiment may be 25°C or higher, 30°C or higher, or 35°C or higher, and may be 55°C or lower, 50°C or lower, or 45°C or lower. The 10% by volume outlet temperature (T10) of the fuel composition of this embodiment may be 45°C or higher, 50°C or higher, or 55°C or higher, and may be 55°C or lower, 50°C or lower, or 45°C or lower. The 20% by volume outlet temperature (T20) of the fuel composition of this embodiment may be 45°C or higher, 50°C or higher, or 55°C or higher, and may be 70°C or lower, 65°C or lower, or 60°C or lower. The 30 volume % outlet temperature (T30) of the fuel composition of this embodiment may be 50°C or higher, 55°C or higher, or 60°C or higher, and may be 80°C or lower, 75°C or lower, or 70°C or lower. The 40 volume % outlet temperature (T40) of the fuel composition of this embodiment may be 55°C or higher, 60°C or higher, or 65°C or higher, and may be 90°C or lower, 80°C or lower, or 70°C or lower. The 50 volume % outlet temperature (T50) of the fuel composition of this embodiment may be 50°C or higher, 55°C or higher, 60°C or higher, or 70°C or higher, and may be 100°C or lower, 90°C or lower, or 80°C or lower. The 60 volume % outlet temperature (T60) of the fuel composition of this embodiment may be 60°C or higher, 65°C or higher, or 70°C or higher, and may be 110°C or lower, 100°C or lower, or 90°C or lower. The 70% by volume outlet temperature (T70) of the fuel composition of this embodiment may be 100°C or higher, 110°C or higher, or 120°C or higher, and may be 100°C or lower, 90°C or lower, or 80°C or lower. The 80% by volume outlet temperature (T80) of the fuel composition of this embodiment may be 90°C or higher, 100°C or higher, or 110°C or higher, and may be 150°C or lower, 140°C or lower, or 130°C or lower. The 90% by volume outlet temperature (T90) of the fuel composition of this embodiment may be 100°C or higher, 110°C or higher, or 120°C or higher, and may be 140°C or lower, 130°C or lower, or 120°C or lower. The 95% by volume outlet temperature (T95) of the fuel composition of this embodiment may be 115°C or higher, 120°C or higher, or 125°C or higher, and may be 160°C or lower, 150°C or lower, or 140°C or lower.The 97% by volume outlet temperature (T97) of the fuel composition of this embodiment may be 120° C. or more, 125° C. or more, or 135° C. or more, and may be 165° C. or less, 155° C. or less, or 145° C. or less. The distillation end point of the fuel composition of this embodiment may be 130° C. or more, 135° C. or more, or 140° C. or more, and may be 170° C. or less, 160° C. or less, or 150° C. or less.

[0038] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. [Example]

[0039] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0040] Example 1 Light cracked gasoline (LCCG) and medium cracked gasoline (MCCG) were prepared as raw materials for the fuel composition. The properties of the light cracked gasoline (LCCG) and medium cracked gasoline (MCCG) are as follows: Light cracked gasoline (LCCG): The content of hydrocarbons with 4 to 6 carbon atoms is 84.0% by volume based on the total amount of LCCG, the content of hydrocarbons with 7 to 8 carbon atoms is 15.2% by volume based on the total amount of LCCG, the initial boiling point is 36.0°C, the 10% by volume outflow temperature (T10) is 44.5°C, the 50% by volume outflow temperature (T50) is 56.0, the 90% by volume outflow temperature (T90) is 84.5°C, and the end point is 186.0°C. Medium cracked gasoline (MCCG): The content of hydrocarbons with 4 to 6 carbon atoms is 84.0% by volume based on the total amount of MCCG, the content of hydrocarbons with 7 to 8 carbon atoms is 0.3% by volume based on the total amount of MCCG, the initial boiling point is 136°C, the 10% by volume outflow temperature (T10) is 143.5°C, the 50% by volume outflow temperature (T50) is 151.5°C, the 90% by volume outflow temperature (T90) is 167.0°C, and the end point is 186.0°C.

[0041] A fuel composition having the composition shown in Table 1 below was obtained by mixing 87% by volume of light cracked gasoline and 13% by volume of medium cracked gasoline. The composition of the fuel composition was measured in accordance with JIS K 2536-2 "Petroleum products - Testing methods for components, Part 2: Determination of total components by gas chromatography." The distillation properties of the fuel composition are shown in Table 2 below.

[0042] Using the obtained fuel composition, the lean limit and brake thermal efficiency were measured by the following methods. The results are shown in Table 1.

[0043] <Lean limit measurement> The lean limit was measured using the test engine described below by changing the excess air ratio under the conditions of a rotation speed of 2000 rpm, an indicated mean effective pressure of 700 kPa, and the minimum advanced ignition timing (MBT) at which torque is maximized. The lean limit was defined as the excess air ratio at which the rate of change of the indicated mean effective pressure exceeded 3%. The excess air ratio is the air-fuel ratio of the mixture during the test divided by the stoichiometric air-fuel ratio of the fuel composition, and is the reciprocal of the equivalence ratio φ. (Test Engine) Bore x stroke: 75mm x 127.5mm (bore:stroke = 1:1.7) Compression ratio: 14 Injection pressure: 0.3 MPa Injection method: Port injection (PFI) Fuel injection system: Multi-point injection (MPI) Supercharging system: Supercharger (maximum supply pressure: 80kPaG) Exhaust gas recirculation (EGR): No Valve timing: changeable Tumble Flow Enhancement System: Port Shape and Enhancement Adapter Ignition device: 20 coils (can ignite multiple times within a cycle)

[0044] <Net thermal efficiency measurement> Break thermal efficiency was calculated by measuring fuel consumption at an engine speed of 2000 rpm, a break mean effective pressure of 0.4 MPa, and the lean limit using the above test engine, and dividing the output by the input heat. The input heat was calculated from the fuel consumption and the net heating value of the fuel composition. The net heating value was calculated using the gross heating value specified in JIS K 2279, the moisture content specified in JIS K 2275-1, and the hydrogen content specified in the Japan Petroleum Institute method JIS-5S-65-4, using the net heating value estimation method specified in JIS K 2279, Appendix 2.

[0045] Example 2 A fuel composition having the composition shown in Table 1 below was obtained by mixing 79% by volume of light cracked gasoline and 21% by volume of medium cracked gasoline. Using the obtained fuel composition, the lean limit and the brake thermal efficiency were measured in the same manner as in Example 1. The results are shown in Table 1. The distillation properties of the fuel composition are also shown in Table 2 below.

[0046] ( reference Example 3) A fuel composition having the composition shown in Table 1 below was obtained by mixing 65% by volume of light cracked gasoline and 35% by volume of medium cracked gasoline. Using the obtained fuel composition, the lean limit and the brake thermal efficiency were measured in the same manner as in Example 1. The results are shown in Table 1. The distillation properties of the fuel composition are also shown in Table 2 below.

[0047] (Comparative Example 1) A fuel composition having the composition shown in Table 1 below was obtained by mixing 66% by volume of light cracked gasoline and 34% by volume of heavy cracked gasoline. Using the obtained fuel composition, the lean limit and the brake thermal efficiency were measured in the same manner as in Example 1. The results are shown in Table 1. The distillation properties of the fuel composition are also shown in Table 2 below.

[0048] (Comparative Example 2) A fuel composition having the composition shown in Table 1 below was obtained by mixing 59.4% by volume of light cracked gasoline, 30.6% by volume of heavy cracked gasoline, and 10.0% by volume of ethanol. Using the obtained fuel composition, the lean limit and the net thermal efficiency were measured in the same manner as in Example 1. The results are shown in Table 1. The distillation properties of the fuel composition are also shown in Table 2 below.

[0049] (Comparative Example 3) A fuel composition having the composition shown in Table 1 below was obtained by mixing 50.8% by volume of light cracked gasoline, 26.2% by volume of heavy cracked gasoline, and 23.0% by volume of ETBE (ethyl tert-butyl ether). Using the obtained fuel composition, the lean limit and the net thermal efficiency were measured in the same manner as in Example 1. The results are shown in Table 1. The distillation properties of the fuel composition are shown in Table 2 below.

[0050] Comparative Example 4 A fuel composition equivalent to regular gasoline having the composition shown in Table 1 below was prepared as the fuel composition. Using the prepared fuel composition, the lean limit and the brake thermal efficiency were measured in the same manner as in Example 1. The results are shown in Table 1. The distillation properties of the fuel composition are shown in Table 2 below.

[0051] (Comparative Example 5) A high-octane gasoline-equivalent fuel composition having the composition shown in Table 1 below was prepared as a fuel composition. Using the prepared fuel composition, the lean limit and the brake thermal efficiency were measured in the same manner as in Example 1. The results are shown in Table 1. The distillation properties of the fuel composition are shown in Table 2 below.

[0052] In Table 1, the units of the numerical values showing the proportions of each component are % by volume.

[0053] [Table 1]

[0054] [Table 2]

Claims

1. The content of hydrocarbons having 7 and 8 carbon atoms is 25% by volume or more, based on the total amount of the fuel composition; the proportion of olefins having 7 and 8 carbon atoms in the hydrocarbons having 7 and 8 carbon atoms is 15% by volume or more; A fuel composition for lean-burn engines, having a carbon number 7 and carbon number 8 isoparaffin content of 6% by volume or more based on the total amount of the fuel composition.

2. 2. The fuel composition for lean-burn engines according to claim 1, wherein the 50% by volume distillation temperature (T50) is 50°C or higher.

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