JP5140858B2 - Fuel oil composition for premixed compression self-ignition combustion - Google Patents

Description

  The present invention relates to fuels for automobile engines and the like, and more particularly, to a fuel oil composition capable of achieving a wide range of premixed compression self-ignition combustion exhibiting excellent ignitability, excellent exhaust gas characteristics and high thermal efficiency. .

In recent years, attention has been focused on regional air pollution problems as well as global warming, and reduction of carbon dioxide (CO ₂ ) and reduction of nitrogen oxides (NOx) and particulate matter (PM) are desired. . Automobiles are one of the major sources of air pollutants, and there is a need to improve energy efficiency and reduce emissions. One internal combustion engine that drives automobiles is a gasoline engine in which a premixed mixture of fuel and air is compressed by a piston, spark ignited, and burned by flame propagation. The gasoline engine emits exhaust gas to operate near the stoichiometric air-fuel ratio. Although post-processing is easy, there is a drawback that the thermal efficiency is inferior because the compression ratio is low.

  For high efficiency and low pollution of this gasoline engine, the practical application of premixed compression self-ignition combustion is expected. However, in premixed compression self-ignition combustion, the fuel / air premixed gas is ignited at the same time in many points, so the combustion speed is fast, ignition control is difficult, and the combustion temperature is low, so unburned hydrocarbons ( HC) has many issues for practical use, such as high emissions. Regarding ignition control, control methods on the engine side such as intake air temperature control, compression ratio adjustment, fuel injection system control, use of residual gas or EGR (exhaust gas recirculation) can be mentioned, and research is actively conducted in various fields. (For example, refer nonpatent literature 1). On the other hand, the ignition in the premixed compression autoignition combustion depends on the oxidation reaction of the fuel in a given field, and the chemical structure of the fuel is one of the important factors controlling the premixed compression autoignition combustion. A fuel oil composition that has been developed as having excellent ignitability in premixed compression self-ignition combustion has been proposed (see, for example, Patent Document 1). However, even with such a fuel oil composition, there is a problem that sufficient thermal efficiency, exhaust gas characteristics and possible operating range are limited.

Edited by Fuquan Zhao, Homogeneous Charge Compression Ignition Engines, SAE PT-94. JP 2007-291309 A

  The object of the present invention has been made in view of the above-mentioned conventional situation, and in premixed compression self-ignition combustion with a high compression ratio, it has excellent ignitability, sufficiently excellent exhaust gas characteristics, high thermal efficiency and operation. It is to provide a fuel oil composition with a wide range of possibilities.

As a result of intensive studies to achieve the above object, the present inventors have obtained a fuel oil composition having a specific base composition and a specific base composition that has an octane number lower than that of general gasoline. As a result, the inventors have found that the above object can be achieved.
That is, the present invention provides the following premixed compression self-ignition combustion fuel oil composition in order to achieve the above object.
(1) Research octane number (RON) of 60 to 89, difference between research method octane number (RON) and motor octane number (MON) (RON-MON) of 6 or less, sulfur content of 10 massppm or less, 50% distillation temperature (T50) is 75 ° C to 110 ° C, kinematic viscosity at 15 ° C is 0.5 to 0.7 mm ² / s, surface tension at 25 ° C is 15 to 25 mN / m, aromatic content is 9.7 vol.% Or less, olefin content and aromatic content The total amount of is 9.7 vol.% Or less, among the prepared base materials used for the preparation, the blending amount of the base material with an aroma content of 90 vol.% Or more is 10 vol.% Or less, A premixed compression self-ignition combustion fuel oil composition characterized in that the blending amount of the base material containing a total of 45 vol.% Or more of aroma and olefin is 40 vol.% Or less.

  According to the premixed compression self-ignition combustion fuel oil composition of the present invention, the premixed compression self-ignition combustion having a high compression ratio is superior in ignitability as compared with the case of using general gasoline, Sufficiently good exhaust gas properties, high thermal efficiency and an extended operating range are achieved. The above-described excellent effects of the fuel oil composition of the present invention are considered to be achieved by a combination of the requirements regarding the properties of the fuel oil composition defined in the present invention and the requirements regarding the preparation base material used for the preparation. Even if any of these requirements is lacking, the above-mentioned excellent effects of the fuel oil composition of the present invention cannot be achieved.

Hereinafter, the contents of the present invention will be described in more detail.
The fuel oil composition for premixed compression self-ignition combustion of the present invention has a research octane number (RON) of 60 or more and 89 or less, preferably 63 or more and 86 or less. When RON is less than 60, pre-ignition compression self-ignition combustion may cause pre-ignition that self-ignites earlier than the top dead center, and appropriate combustion cannot be achieved. On the other hand, if it is higher than 89, it is necessary to set the intake air temperature high in order to ignite, and in addition to the deterioration of fuel efficiency due to a decrease in intake efficiency, premixed compression self-ignition may not be achieved.

  The premixed compression self-ignition combustion fuel oil composition of the present invention preferably has a motor octane number (MON) of 54 or more and 89 or less, more preferably 57 or more and 88 or less. If MON is 54 or more and 89 or less, self-ignition of the air-fuel mixture occurs at an appropriate time, and emission of unburned hydrocarbon (HC), carbon monoxide (CO), etc. can be suppressed in premixed compression self-ignition combustion. .

  In the premixed compression self-ignition combustion fuel oil composition of the present invention, the difference (RON-MON) between the research octane number (RON) and the motor octane number (MON) is 6 or less, preferably 5.5 or less. If RON-MON exceeds 6, emissions of unburned hydrocarbons (HC), carbon monoxide (CO), etc. may increase in premixed compression ignition self-combustion. RON and MON can be measured according to JIS K 2280.

  The fuel oil composition for premixed compression self-ignition combustion of the present invention has a sulfur content of 10 massppm or less, preferably 8 massppm or less. When the sulfur content is 10 massppm or less, it is possible to prevent the exhaust gas purification catalyst from lowering its capacity and to prevent the concentration of NOx, CO and HC in the exhaust gas from increasing. The sulfur content can be measured according to JIS K 2541.

  The fuel oil composition for premixed compression self-ignition combustion of the present invention has a 50% distillation temperature (T50) of 75 ° C to 110 ° C, preferably 75 ° C to 105 ° C, more preferably 75 ° C to 95 ° C. It is a range. When T50 is within the above range, characteristics as an internal combustion engine for automobiles such as drivability and acceleration can be exhibited. T50 can be measured according to JIS K 2254.

  In the premixed compression self-ignition combustion fuel oil composition of the present invention, the 70 ° C. effluent (E70) is preferably in the range of 18 to 40 vol.%, More preferably in the range of 20 to 40 vol.%. is there. If E70 is within the above range, it is easy to form a fuel-air premixed gas, and characteristics such as drivability and acceleration as an automotive internal combustion engine can be exhibited.

The premixed compression self-ignition combustion fuel oil composition of the present invention has a kinematic viscosity at 15 ° C. of 0.5 to 0.7 mm ² / s, preferably 0.51 to 0.69 mm ² / s. If the kinematic viscosity is within the above range, appropriate fuel spraying is achieved, the formation of a fuel-air premixed gas is facilitated, and incomplete combustion products such as HC and CO can be suppressed. The kinematic viscosity can be measured according to JIS K 2249.

  The premixed compression self-ignition combustion fuel oil composition of the present invention has a surface tension at 25 ° C. of 15 to 25 mN / m, preferably 16 to 24 mN / m. If the surface tension is within the above range, appropriate fuel spraying is achieved, the formation of a fuel-air premixed gas is facilitated, and incomplete combustion products such as HC and CO can be suppressed. The surface tension can be measured according to JIS K 2241.

  In the premixed compression self-ignition combustion fuel oil composition of the present invention, the lead vapor pressure (RVP) is preferably in the range of 44 to 93 kPa, more preferably in the range of 50 to 90 kPa. Within the above range, there is no problem in engine startability, and evaporation gas from the vehicle can be suppressed.

  The premixed compression self-ignition combustion fuel oil composition of the present invention has an aroma content of 15 vol.% Or less, preferably 13 vol.% Or less, more preferably 10 vol.% Or less, and a total amount of olefin and aroma. Is 25 vol.% Or less, preferably 20 vol.% Or less, more preferably 15 vol.% Or less. If the aroma content or olefin content exceeds the above upper limit, emission of unburned hydrocarbons (HC), carbon monoxide (CO), etc. may increase in the premixed compression ignition self-combustion. The aroma content and olefin content can be measured in accordance with the Petroleum Institute method JPI-5S-33-90 (gas chromatographic method).

  The premixed compression self-ignition combustion fuel oil composition of the present invention has a blending amount of a base material having an aromatic content of 90 vol. The amount of the base material containing 45% by volume or more of the olefin and the olefin is 40% by volume or less. In preparing the fuel oil composition, if the blending amount of the base material containing 90% or more of these aroma components or the base material containing 45% or more of the aroma and olefin content exceeds the above range, premixing will occur. In compression ignition self-combustion, emissions of unburned hydrocarbons (HC) and carbon monoxide (CO) may increase.

  Examples of the preparation base material used for the preparation of the premixed compression self-ignition combustion fuel oil composition of the present invention include a base material having an aroma content of 90 vol.% Or more, which contacts a heavy straight-run naphtha or the like. Catalysts (for example, alumina) under high temperature and pressure in a hydrogen stream by reforming methods (plating forming method, magna forming method, aromaizing method, reniforming method, hood reforming method, ultra forming method, power forming method, etc.) Of the reformed gasoline obtained by contact treatment with platinum, alleys, and chlorine, etc. on a simple substance), heavy contact reformed gasoline consisting of fractions of 100 ° C or higher separated by distillation, and further A toluene fraction obtained by fractional distillation, a xylene fraction, an aromatic fraction having 9 or more carbon atoms, and the like.

  Further, examples of the preparation base material used for preparing the premixed compression self-ignition combustion fuel oil composition of the present invention include a base material containing a total of 45 vol.% Or more of an aroma content and an olefin content. Petroleum fractions ranging from oil to atmospheric residue, preferably heavy gas oil or vacuum gas oil, are conventionally known catalytic cracking methods, especially fluid catalytic cracking methods (UOP method, shell two-stage method, flexi cracking method, Contact obtained by decomposition with a solid acid catalyst (eg, silica / alumina blended with zeolite) by ultra ortho flow method, texaco method, gulf method, ultra cat cracking method, RCC method, HOC method, etc. Such as cracked gasoline.

  Thus, the premixed compression self-ignition combustion fuel oil composition of the present invention is not particularly limited with respect to the prepared base material except that the base material and the blending amount are limited as described above. The various prepared base materials obtained can be used. For example, from hydrogenated light naphtha, hydrogenated heavy naphtha obtained by desulfurizing light naphtha fraction obtained by atmospheric pressure distillation or heavy naphtha fraction, hydrogenated light naphtha, isomerate obtained from isomerization of hydrogenated light naphtha, and alkylation equipment A base material having a relatively small amount of aroma and olefin such as an alkylate obtained and a light reformate obtained from a catalytic reformer can be suitably used. Further, a GTL naphtha fraction obtained by FT reaction from synthesis gas and a naphtha obtained by hydrocracking a WAX content obtained by FT reaction can also be used.

  The light naphtha is a light fraction obtained by distilling a straight-run naphtha obtained by desulfurizing a straight-run naphtha obtained by atmospheric distillation of crude oil into a light fraction and a heavy fraction by distillation. The light naphtha used in the fuel oil composition has a RON of 65 or more, preferably 67 or more, a Reid vapor pressure (RVP) of 80 kPa or more, preferably 85 kPa or more, a boiling point range of 25 to 100 ° C., and a T50 of 65 ° C. or less. Desirably, it has a property of 60 ° C. or less, an aroma content of 5 vol.% Or less, preferably 3 vol.% Or less, and an olefin content of 2 vol.% Or less, preferably 1.5 vol.

  The heavy naphtha is a heavy fraction obtained by distilling a straight-run naphtha obtained by desulfurizing a straight-run naphtha obtained by atmospheric distillation of crude oil into a light fraction and a heavy fraction by distillation. Heavy naphtha used in the fuel oil composition has a RON of 40 or more, preferably 42 or more, a boiling range of 80 to 180 ° C., a T50 of 130 ° C. or less, preferably 120 ° C. or less, and an aromatic content of 15 vol.% Or less, preferably Preferably has a property of 10 vol.% Or less and an olefin content of 2 vol.% Or less, preferably 1.5 vol.% Or less.

  The alkylate is obtained by reacting isobutane and a lower olefin (butene, propylene, etc.) as raw materials in the presence of an acid catalyst (sulfuric acid, hydrogen fluoride, aluminum chloride, etc.). In the fuel oil composition of the present invention, various alkylates can be used, but the C8 fraction is 65 vol.% Or more, preferably 70 vol.% Or more, and isooctane (2,2,4-trimethyl). Pentane) is 28 vol.% Or more, preferably 30 vol.% Or more. The alkylate should have a RON of 93 or more, preferably 94 or more, and a T50 of 104 ° C. or more, preferably 105 ° C. or more.

  Furthermore, the fuel oil composition of the present invention is mainly composed of butane and butenes obtained by distillation during atmospheric distillation of crude oil, crude oil, etc., during the production of reformed gasoline, or during the production of cracked gasoline. It is also preferable to blend isomerate obtained by isomerization of C4 fraction, straight chain lower paraffin hydrocarbon, or isopentane obtained by precision distillation of isomerate.

  In addition, the above-mentioned light reformate is a method of contact reforming of heavy straight-run naphtha, etc. (Platforming method, Magnaforming method, Aromaizing method, Reniforming method, Food reforming method, Ultraforming method, Power forming method, etc. ) By distilling the reformed gasoline obtained by contact treatment with a catalyst (for example, an alumina carrier carrying platinum, rhodium and chlorine) under high temperature and pressure in a hydrogen stream, A light fraction divided into a benzene fraction and a heavy fraction, and the fuel oil composition of the present invention has a RON of 70 or more, preferably 73 or more, a boiling range of 25 to 100 ° C., and a T50 of 40 ° C. or more, preferably Is desirable to have a temperature of 43 ° C. or more, an aroma content of 5 vol.% Or less, preferably 3 vol.% Or less, and an olefin content of 3 vol.% Or less, preferably 2 vol.

  The naphtha obtained by hydrocracking the GTL naphtha fraction obtained by the Fischer-Tropsch (FT) reaction from the synthesis gas and the WAX content obtained by the FT reaction is divided into a light naphtha fraction and a heavy naphtha depending on the boiling range. It can be divided into fractions, each having a boiling range of 25-100 ° C and 100-180 ° C, with an aroma content of 5 vol.% Or less, preferably 3 vol.% Or less, and an olefin content of 3 vol.%. In the following, it is desirable that the content is 2 vol.% Or less.

  The premixed compression self-ignition combustion fuel oil composition of the present invention uses the above-mentioned various base materials as preparation base materials, provided that the amount of the constant base material is limited as described above, It can prepare by mixing suitably so that it may have the property prescribed | regulated by the said invention.

Also, the fuel oil composition of the present invention obtained, preferably 15 ℃ density is in the range of 0.650~0.783g / cm ^3, more preferably of 0.650~0.770g / cm ³ It is a range. If the density is within the above range, it is possible to suppress the reduction in vehicle fuel consumption and the emission of unburned hydrocarbons and carbon monoxide.

  Various additives can be appropriately blended in the premixed compression self-ignition combustion fuel oil composition of the present invention as necessary. The additives include metal deactivators such as thioamide compounds, surface ignition preventives such as organophosphorus compounds, detergent dispersants such as succinimides, polyalkylamines, polyetheramines, polyisobutyleneamines, and polyhydric alcohols. And anti-icing agents such as ethers, alkali metals and alkaline earth metal salts of organic acids, auxiliary alcohols such as sulfates of higher alcohols, anionic surfactants, cationic surfactants, amphoteric surfactants, etc. Known fuel additives such as inhibitors, rust inhibitors such as alkenyl succinates, and colorants such as azo dyes may be mentioned. These can be added singly or in combination. The addition amount of these fuel additives is arbitrary, but usually the total addition amount is preferably 0.1% by mass or less.

  The content of the present invention will be described in more detail with reference to Examples and Comparative Examples below, but the present invention is not limited thereto.

Examples 1-10, Comparative Examples 1-7
Fuel oil compositions were prepared using the base materials having the properties shown in Table 1 according to the formulation shown in Table 2, and fuel oil compositions of Examples 1 to 10 and Comparative Examples 1 to 7 shown in Table 3 were obtained. The obtained fuel oil composition was subjected to various performance evaluation tests described below. The test results are shown in Table 4.

Of the base materials shown in Table 1, C4 is butane, UFT-LN is a hydrogenated light naphtha (boiling point of about 30 to 90 ° C) obtained by hydrorefining straight-run light naphtha, and UFT-HN is hydrogen of straight-run heavy naphtha. Hydrogenated heavy naphtha (boiling point: about 100-150 ° C), Isomerate hydroisomerized straight-run light naphtha and then isomerized isomerate (boiling point: about 30-80 ° C), L-RMT: straight-run heavy naphtha Light reformate (boiling point around 30-70 ℃) mainly composed of a fraction lighter than reformed benzene obtained by reforming after hydrorefining, H-RMT is reforming after hydrotreating straight-run heavy naphtha The resulting reformate is a heavy reformate mainly composed of heavier fractions than benzene (boiling point 100-170 ° C), Alkylate is alkylate (boiling point 30-180 ° C) obtained from alkylation equipment, L -FCCG is fluid catalytic cracker Light FCC gasoline (boiling point of about 30-90 ° C) obtained from the tank, FCCG is FCC gasoline fraction obtained from the fluid catalytic cracking unit (boiling point of about 30-200 ° C), HCN is heavy FCC obtained from the fluid catalytic cracking unit Gasoline fraction (boiling point 100 ~ 200 ℃), GTL- St- LN is hydrorefined light naphtha fraction obtained from synthesis gas by FT synthesis (boiling point 30 ~ 80 ℃), GTL-St- HN is a hydrorefining process of heavy naphtha fraction obtained from synthesis gas by FT synthesis (boiling point 90 ~ 150 ℃), GTL-Cr-LN is hydrocracking WAX fraction obtained from synthesis gas by FT synthesis. Light naphtha fraction obtained by treatment (boiling point 30 ~ 80 ℃), GTL-Cr-HN is heavy naphtha fraction (boiling point 90 ~) obtained by hydrocracking WAX fraction obtained by FT synthesis from synthesis gas About 150 ° C).

  In the table, RON and MON are JIS K 2280, density is JIS K 2249, vapor pressure is JIS K 2258, sulfur content is JIS K 2541, E70 and T50 are JIS K 2254, and aroma and olefin content is Japan Petroleum Institute law. JPI-5S-33-90 (gas chromatographic method), kinematic viscosity was measured according to JIS K 2249, and surface tension was measured according to JIS K 2241.

(Engine used for testing)
An in-cylinder direct fuel injection engine with inline 4-cylinder, 2000cc displacement and compression ratio of 14 DOHC 4valve was used. The engine is installed in an engine bench dynamo, and the pressure in the combustion chamber can be measured by an in-cylinder pressure sensor.

(Ignition test)
The self-ignition timings of the fuel oil compositions of Examples and Comparative Examples were measured under the conditions that the engine speed was 1500 rpm, the intake air temperature was constant at 200 ° C., and the air-fuel ratio was 50. At this time, the case where the ignition has occurred 10 ° or more before the top dead center is `` premature ignition '', the case where the ignition timing is from 10 ° before the top dead center to 10 ° after the top dead center, It was defined as “appropriate ignition timing”, and “not ignited” was defined as a case where a fire did not ignite even after 10 ° after top dead center.

(Fuel consumption / exhaust gas test)
Fuel when operating by adjusting the intake air temperature so that the ignition timing is in the range of 10 ° before top dead center to 10 ° after top dead center under the conditions of engine speed of 1500rpm and indicated mean effective pressure of 250kPa The consumption rate, HC and CO emissions were measured. Fuel consumption was measured by a fuel flow meter, and exhaust gas was measured by an engine exhaust gas measuring device.
When fuel consumption is 200 g / kWh or less, it is judged that good fuel consumption characteristics are obtained, and when HC is 2500 ppm or less and CO is 0.18% or less, the incomplete combustion of exhaust gas emitted from the engine is sufficiently low It was judged.

(Operating range test)
At an engine speed of 1500 rpm, the range of the indicated mean effective pressure where the knocking strength was 50 kPa or less and the COV (the fluctuation rate of the indicated mean effective pressure obtained by the combustion finger pressure) was 5% or less was adjusted while adjusting the intake air temperature. When the upper limit of the indicated mean effective pressure is 400 kPa or more, it was determined that premixed compression self-ignition combustion was achieved extensively.

As is apparent from Table 4, the fuel oil compositions of the examples of the present invention exhibit an appropriate premixed compression autoignition timing, are excellent in fuel consumption rate, HC and CO exhaust gas levels, and It can be seen that the operable range of the mixed compression self-ignition combustion is sufficiently wide.
On the other hand, in the case of the fuel oil composition in which RON is not in the range of 60 or more and 89 or less as in Comparative Examples 1 and 6, it can be seen that the premixed compression self-ignition timing is not appropriate and the operable range is narrow.
In addition, in the case of a fuel oil composition in which the amount of RON-MON and the amount of aroma and the amount of aroma + olefin is outside the above specified range as in Comparative Examples 3 and 4, the HC and CO emission levels are high or the operable range is narrow. I understand.
Furthermore, when RON, RON-MON, and the amount of aroma and the amount of aroma + olefin are outside the above specified ranges as in Comparative Examples 2 and 5, the premixed compression self-ignition timing is not appropriate, and the HC and CO emission levels It can be seen that the range is high and the operable range is narrow.
Even in the case where RON is in the range of 60 to 89, in Comparative Example 7 where the kinematic viscosity, surface tension, etc. are outside the specified ranges, the HC and CO emission levels are the highest and the operable range is narrow. Recognize.

  According to the premixed compression self-ignition combustion fuel oil composition of the present invention, the premixed compression self-ignition combustion having a high compression ratio is superior in ignitability as compared with the case of using general gasoline, The fuel oil composition of the present invention is expected to be widely used in premixed compression self-ignition combustion internal combustion engines because sufficiently good exhaust gas characteristics, high thermal efficiency, and expansion of the operable range are achieved.

Claims (1)

Research method octane number (RON) of 60 to 89, difference between research method octane number (RON) and motor method octane number (MON) of 6 or less, sulfur content of 10 massppm or less, 50% distillation temperature (T50) Is 75 ° C to 110 ° C, kinematic viscosity at 15 ° C is 0.5 to 0.7 mm ² / s, surface tension at 25 ° C is 15 to 25 mN / m, aromatic content is 9.7 vol.% Or less, total amount of olefin and aromatic content Has a property of 9.7 vol.% Or less, and among the blended base materials used for the preparation, the blending amount of the base material having an aroma content of 90 vol.% Or more is 10 vol.% Or less, and the aroma content A premixed compression self-ignition fuel oil composition characterized in that the amount of the base material containing 45% by volume or more of olefins is 40% by volume or less.