EP3055389A1

EP3055389A1 - Fuel oil composition comprising an ft derived oil, a cracked gas oil and a residual carbon adjusting component

Info

Publication number: EP3055389A1
Application number: EP14787115.6A
Authority: EP
Inventors: Tsutomu Yoshida; Ayumi Takahashi; Yasuyuki Komatsu
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 2013-10-08
Filing date: 2014-10-08
Publication date: 2016-08-17
Also published as: JP2015074695A; JP6198554B2; WO2015052261A1

Abstract

To offer a Fuel Oil "A" composition which has good ignition characteristics, has superior oil filter permeability, has good fuel consumption and is easy to manufacture, and a method of manufacture thereof. The composition is a Fuel Oil "A" composition which contains an FT synthesis oil, a cracked gas oil and a residual carbon adjusting component and which has a density of from 0.820 to 0.890 g/cm3, a residual oil carbon/hydrogen ratio after a 95% cut by ASTM distillation of not more than 6.4, and a 10% residual oil carbon residue in excess of 0.20 mass%.

Description

FUEL OIL COMPOSITION COMPRISING AN FT DERIVED OIL, A CRACKED GAS OIL AND A RESIDUAL CARBON ADJUSTING COMPONENT

This invention relates to oils corresponding to heavy fuel oils of Class 1, No. 1 and No. 2 in JIS K 2205, and to a Fuel Oil "A" composition, which has good ignition characteristics, superior oil filter

permeability and good consumption and which is easy to manufacture, and a method of manufacture thereof.

Fischer-Tropsch derived oils (referred to

hereinafter as FT derived oils) are synthesised from sources such as natural gas, coal and biomass, and so contain no sulphur or aromatics. For this reason, FT derived oils can be used as blending components to produce fuels which are better for the environment in that they inhibit emissions of sulphur oxides and particulate matter (PM) during combustion, as compared with fuels having no FT derived components. In recent years, FT derived oils have also been used as a blending component in Fuel Oil "A" .

When Fuel Oil "A" is manufactured and sold, a 10% residual oil carbon residue is made to exceed 0.20 mass% so that it is possible to classify it with gas oil compositions from the viewpoint of tax legislation (Light Oil Delivery Tax) . To do so, it is necessary to add small amounts of a heavy oil fraction (referred to hereinafter as the residual carbon adjusting component) such as residual oil, which contains a carbon residue to the kerosene/gas oil fraction. Due to the addition of the residual oil, as compared with kerosene and gas oil, certain constituents in the residual carbon adjusting component cause problems, such as the clogging of filters installed in fuel supply systems. Additionally, as with the case of using FT derived oils as a blending component in Fuel Oil "A" compositions, reduced oil filter permeability caused by the residual carbon adjusting component. Therefore, attempts are being made to improve oil filter

permeability of Fuel Oil "A" compositions in which FT derived oils are used as a blending component.

For example, Japanese Laid-open Patent 2007-269926 has proposed mixing an extract oil using as a residual carbon adjusting component a Fuel Oil "A" composition in which an FT derived oil is a base material.

Detailed Description of the Invention

When using an extract oil as a residual carbon adjusting component, it is generally preferred to manufacture such fuels in manufacturing installations that include or are situated near lubricating oil manufacturing plant, or in a manufacturing installation wherein it is possible to introduce the extract oil.

Also, even when using other residual carbon adjusting components, it is unclear what effect the characteristics of the residual carbon adjusting component will have on the oil filter permeability of Fuel Oil "A" when an FT derived oil has been used as a Fuel Oil "A" blending component .

When using an FT derived oil as a blending component for Fuel Oil "A", it is believed that one potential reason for the reduced oil filter permeability may be caused by the residual carbon adjusting component and that FT derived oils contain no aromatics. Therefore, to alleviate the loss of oil filter permeability,

consideration has been given to methods of incorporating aromatics, but it is not clear which aromatic components are effective in improving oil filter permeability. At the same time, while FT derived oils have good ignition qualities as a result of being aromatics-free and a resulting high cetane index, and the added benefit of being good for the environment, there is concern that FT derived oils may be detrimental to fuel consumption because due to low calorific value.

Currently, as there is a change from using Fuel Oil "A" to natural gas as a fuel, heavy Fuel Oil "A" or the cracked light gas oil which is used as one of its blending components have become surplus. Therefore, it is necessary to make effective use of the cracked gas oil which has become somewhat surplus in many manufacturing installations in order to bring about a resolution of problems such as clogging of Fuel Oil "A" filters. The cracked gas oil has a high aromatics content, and the possibility exists of being able to alleviate the deterioration in oil filter permeability due to the use of FT derived oils . Merely blending in the cracked gas oil, however, will result in a decrease in the cetane index, ignition qualities will be adversely affected, as well as unsatisfactory ignition or slow starting in combustion devices, such as for example, diesel engines or boilers .

The aim of the present invention is therefore to provide a Fuel Oil "A" composition having good ignition characteristics, superior oil filter permeability, good fuel consumption characteristics, and which is easy to manufacture, as well as providing a method of manufacture thereof .

In order to achieve the aforementioned goals, the inventors have considered the characteristics of FT derived oils and cracked gas oils, and the residual carbon adjusting components currently used. After extensive research into the effect of these

characteristics on the performance of oil filter

permeability of Fuel Oil "A", a novel Fuel Oil "A" composition has been discovered which unexpectedly provides good ignition characteristics, superior oil filter permeability and good fuel consumption

characteristics. Additionally, it is easy to

manufacture. In one embodiment, there is provided a Fuel Oil "A" composition which contains an FT derived oil, a cracked gas oil and a residual carbon adjusting

component, providing a fuel composition having a density of between 0.820 and 0.890 g/cm3, a residual oil

carbon/hydrogen ratio after a 95% cut by ASTM

distillation of not more than 6.4, preferably between 3 and 6.4, and a 10% residual oil carbon residue in excess of 0.20 mass%. The invention also offers a method of manufacture of a Fuel Oil "A" composition, the method including the steps of providing a process in which an FT derived oil having a density of not less than 0.770 g/cm3 (at 15°C), a normal paraffins of carbon number 21 or higher in the amount of between 2.0 and 10.0 mass% and a cracked gas oil having a density of not less than 0.860 g/cm3 (at 15°C), an aromatic content of not less than 50.0 vol.%, and a dicyclic or higher aromatics content of not less than 40.0 vol.% are mixed together.

As mentioned above, according to this invention it is possible to offer a Fuel Oil "A" composition which has good ignition characteristics, superior oil filter permeability and good consumption and which is easy to manufacture.

In certain embodiments, the Fuel Oil "A" composition of the present invention includes as blending components an FT derived oil and a cracked gas oil. The FT derived oil can be obtained by means of Fischer-Tropsch synthesis using natural gas, coal or biomass or the like as the raw material. From the standpoint of economy and ease of procurement, it is preferable if the FT synthesis oil is a GTL with natural gas as the raw material. Other blending components may be incorporated in the blend, such as for example, light oil fractions such as

desulphurised gas oil, straight-run gas oil, directly desulphurised gas oil or indirectly desulphurised gas oil, and kerosene fractions such as desulphurised kerosene and straight-run kerosene.

In addition, the Fuel Oil "A" composition of the present invention can include a residual carbon adjusting component. For the residual carbon adjusting component it is possible to use, apart from atmospheric residues obtained by atmospheric distillation of oil or vacuum residues obtained by atmospheric distillation of oil, deasphalted asphalt obtained after a deasphalting treatment of atmospheric residues or vacuum residues, or residual oils (slurry oils) obtained from fluid catalytic cracking apparatus. On the basis of social requirements of recent years, it is preferable to increase the proportion of these mixtures as much as possible. When using Fuel Oil "C" blending components of low added value, it is preferable if the residual carbon adjusting component has a high carbon residue. Extract oils obtained after extractive removal, through dissolving with a solvent, of aromatics from atmospheric residues or vacuum residues are, as already mentioned, suitable from the standpoint of, for example, ease of manufacture.

Furthermore, certain Fuel Oil "A" composition embodiments of this invention may also include additives. Exemplary additives can include one or more of low- temperature flow improvers, cetane number improvers, surfactants, rust-prevention agents, detergents,

lubricity improvers and markers .

The type and amount of blending components used should be in a range that satisfies the make-up

requirements of the Fuel Oil "A" composition pertaining to this invention. For example, in the case of the FT synthesis oil, it is preferred that the Fuel Oil "A" composition contains between 1.0 and 50.0 vol.%, more preferably between 10.0 and 45.0 vol.%, and even more preferably between 25.0 and 35.0 vol.%. In the case of the cracked gas oil, it is preferred that the Fuel Oil "A" composition contains between 5.0 and 50.0 vol.%, more preferably between 10.0 and 40.0 vol.%. If desulphurised gas oil is included, it is possible for the amount to be, for example, between 20.0 and 50.0 vol.%. In the case of the residual carbon adjusting component, it is preferable that the Fuel Oil "A" composition contains not less than 0.2 vol.%, but more preferably between 0.3 and 3.0 vol.%.

The Fuel Oil "A" composition in certain embodiments of the invention preferably has an aromatics content of not less than 15.0 vol.%. Exemplary aromatics can include monocyclic aromatics having an alkyl group on benzene or a naphthene ring, dicyclic aromatics having an alkyl group on naphthalene or naphthene rings, and tricyclic aromatics having an alkyl group on

phenanthrolene or anthracene or naphthene rings . Because the presence of aromatics increase the solubility of sludge and thus increase the ability for oil to pass through filters, the aromatics content is more preferably not less than 20.0 vol.%, even more preferably not less than 23.0 vol.%. However, if the aromatics content is too high, the cetane index decreases, resulting in problems such as poor engine starting characteristics, so aromatics content is preferably not greater than 50.0 vol.%, more preferably not greater than 45.0%, and even more preferably not greater than 43.0 vol.%. In certain embodiments, the aromatics content is between 15.0 and 50 vol.%, alternatively between 20 and 45 vol.%,

alternatively between 23 and 43 vol.%. Adjustment of aromatics content can be achieved by suitable means, such as varying the characteristics of the cracked gas oil or the proportion of cracked gas oil in the Fuel Oil "A" composition .

The Fuel Oil "A" composition of the present

invention preferably includes in the aromatics not less than 5.0 vol.% of dicyclic or higher aromatics, but more preferably not less than 15.0 vol.%, and even more preferably not less than 25.0 vol.%. To regulate the dicyclic or higher aromatic content, operating conditions of the fluid catalytic cracking apparatus can be adjusted during manufacture of the cracked gas oil, or the proportions of FT derived oil and cracked gas oil may be adjusted. To ensure reduced filter clogging,

consideration should be given to the balance between 10% carbon residue and cetane index, while preferably adjusting the dicyclic or higher aromatic content on the basis of the undermentioned residual oil carbon/hydrogen ratio after a 95% cut by ASTM distillation (hereinafter sometimes referred to simply as the carbon/hydrogen ratio) .

The Fuel Oil "A" composition of the present

invention preferably includes a content of normal paraffins of carbon number 21 or higher of between 0.1 and 4.0 mass%, more preferably between 0.5 and 4.0 mass%, and more preferably between 1.0 and 3.5 massl. In certain embodiments, it is preferred that the normal paraffins of carbon number 21 or higher is between 2.0 and 3.0 mass%. If the content of normal paraffins of carbon number 21 or higher is too large, the oil filter permeability may decrease, and if it is too small the cetane index may become too low, which is undesirable. The content of normal paraffins of carbon number 21 or higher can be adjusted by, for example, adjusting the manufacturing conditions of the FT derived oil so that the normal paraffins of carbon number 21 or higher in the

FT derived oil becomes not more than 10.0 mass%, or by suitably adjusting the proportions of the FT derived oil and cracked gas oil mixture.

The Fuel Oil "A" composition of the present

invention can have a residual oil carbon/hydrogen ratio after a 95% cut by ASTM distillation of not more than 6.4, preferably between 6.0 and 6.3, and more preferably between 6.2 and 6.3. If the carbon/hydrogen ratio is outside the aforementioned range, clogging of the filter may occur, and it may not be possible to improve the oil filter permeability sufficiently. Adjustment of the carbon/hydrogen ratio can be achieved, for example, by adjusting the operating conditions of the distillation apparatus such as atmospheric pressure distillation apparatus so that the density of the residual carbon adjusting component becomes not less than 0.931 g/cm3, or by suitably adjusting the proportions of the kerosene/gas oil fractions .

In an effort to reduce sulphur oxides in exhaust gases, the sulphur content of the Fuel Oil "A"

composition is preferably not more than 0.15 massl.

The Fuel Oil "A" composition of the present

invention can have a density of between 0.820 and 0.890 g/cm3, preferably between 0.850 and 0.880 g/cm3. If the density is too low, fuel consumption will deteriorate. If the density is too high, the cetane index decreases, and ignition qualities and combustion qualities may be reduced.

The Fuel Oil "A" composition of the present

invention can have a kinematic viscosity (at 50°C) of between 2.0 and 4.5 mm2/s, preferably between 2.0 and 2.5 mm2/s. If the kinematic viscosity is too low, lubricity performance is reduced. If the kinematic viscosity is too high, atomisation inside the burner decreases and it may cause deterioration of the nature of the exhaust gases .

The Fuel Oil "A" composition of the present

invention should have a cold filter plugging point of not more than -2°C.

In the distillation characteristics of the Fuel Oil "A" composition of the present invention the 10%

distillation temperature is preferably between 195 and 260°C, more preferably between 230 and 250°C. If the 10% distillation temperature is too low, white smoke is likely to occur during combustion, and if it is too high there is a risk that low-temperature starting

characteristics will deteriorate. The 50% distillation temperature is preferably between 260 and 310°C, more preferably between 270 and 300°C, and even more

preferably between 280 and 290°C. If the 50%

distillation temperature is too low, there may be an effect on fuel consumption and ignition characteristics, and if it is too high there is a possibility that low- temperature starting characteristics will deteriorate. The 90% distillation temperature is preferably between 315 and 370°C, more preferably between 320 and 350°C, and even more preferably between 320 and 340°C. If the 90% distillation temperature is too low, there may be an effect on ignition characteristics, and if it is too high there is a possibility that low-temperature starting characteristics will deteriorate or black smoke in the combustion exhaust gases will increase.

The Fuel Oil "A" composition of the present

invention preferably has a cetane index of not less than 40, but preferably not less than 45. The cetane index is preferably high from the standpoint of ignition qualities but if it is too high there is a possibility that the exhaust gas characteristics will deteriorate, and so it is preferably less than 70 and more preferably less than 60. As regards oil filter permeability, the pressure difference before and behind the filter after one hour of oil passing through a membrane filter under flow rate conditions of 1.0 L/h can be taken for example as 0.7 kg/cm2. Calorific value can be taken as a measure for fuel consumption, and the calorific value can for example be evaluated as being good at 37500 kJ/L or higher. The

Fuel Oil "A" composition pertaining to this invention can be manufactured even without using an extract oil, and a Fuel Oil "A" composition with good ignition

characteristics, superior oil filter permeability and good fuel consumption can be easily manufactured.

Also provided is a method of manufacture of the Fuel Oil "A" composition of the present invention, and manufacture may for example be as follows .

An FT derived oil of density (at 15°C) not less than 0.770 g/cm3 and content of normal paraffins of carbon number 21 or higher of between 2.0 and 10.0 mass% is mixed together with a cracked oil of density (at 15°C) not less than 0.860 g/cm3, an aromatic content not less than 50.0 vol.%, and dicyclic or higher aromatic content of not less than 40.0 vol.% and with a residual carbon adjusting component. A desulphurised gas oil may also be mixed in .

The FT derived oil can be obtained by, for example, gasifying natural gas to obtain syngas (carbon monoxide and hydrogen), performing FT synthesis, and hydrocracking and distilling the synthesis obtained. The cracked gas oil can be obtained for example from distillation operations after cracking in fluid catalytic cracking apparatus with directly desulphurised residual oil or indirectly desulphurised residual oil or vacuum gas oil as the raw material.

Examples

Examples of Embodiment 1 - 5, Comparative Examples 1

- 4. The FT derived gas oil (density (at 15°C) 0.782 g/cm3, initial boiling point 202°C, 10% distillation temperature 239°C, 50% distillation temperature 285°C, 90% distillation temperature 328°C, end point 342°C, flash point 92°C, cetane index 89.2, kinematic viscosity

(30°C) 3.966 mm2/s, sulphur content not more than 1 mass ppm, aromatic content not more than 1 vol.%, normal paraffins of carbon number 8 - 20 of 29.80 mass%, normal paraffins of carbon number 21 or higher of 9.15 massl) and catalytically cracked gas oil (density (at 15°C)

0.946 g/cm3, monocyclic aromatics of 17.7 vol.%, dicyclic aromatics of 49.3%, dicyclic and higher aromatics of 59.5 vol.%, tricyclic and higher aromatics of 10.2 vol.%), desulphurised gas oil and residual carbon adjusting components shown in Table 1 were mixed in the blend amounts (vol.%) shown in Table 1, and the Fuel Oil "A" compositions pertaining to Embodiments 1 - 5 and

Comparative Examples 1 - 4 were obtained. The aforementioned characteristics were obtained by measuring in the same way as for the Fuel Oil "A" compositions obtained .

The following were used for the residual carbon adjusting component: "Residual carbon adjusting component 1", slurry oil of density (15°C) 1.033 g/cm3, distilled from a fluid catalytic cracking apparatus, sulphur content 0.79 mass% and carbon residue 5.91 mass%;

"Residual carbon adjusting component 2", atmospheric pressure residual oil of density (15°C) 0.939 g/cm3, obtained from processing in atmospheric distillation apparatus of a Middle East crude of sulphur content 1.00 mass%, sulphur content 2.15 mass% and carbon residue 5.95 mass%; and "Residual carbon adjusting component 3 " , atmospheric pressure residual oil of density (15°C) 0.993 g/cm3, obtained from processing in atmospheric

distillation apparatus of a Middle East crude of sulphur content 2.92 mass%, sulphur content 3.55 mass% and carbon residue 12.0 mass%.

Table 1

Measurements were taken for the following

characteristics for the Fuel Oil "A" compositions of Examples of Embodiment 1 - 5 and Comparative Examples 1 - 4. The results are shown in Tables 2 and 3.

Kinematic viscosity (at 50°C) : Measured in

accordance with JIS K 2283 "Crude petroleum and petroleum products - Determination of kinematic viscosity and calculation of viscosity index from kinematic viscosity." 10% residual oil carbon residue: Measured in accordance with JIS K 2270 "Crude petroleum and petroleum products -Determination of carbon residue."

Plugging point : Measured in accordance with JIS K 2288 "Petroleum products - Fuel oil - Determination of cold filter plugging point."

Density (at 15°C) : Measured in accordance with JIS

K 2249 "Crude petroleum and petroleum products - Determination of density and density, mass, volume conversion tables."

ASTM distillation: Measured in accordance with JIS K 2254 "Petroleum products - Determination of

distillation characteristics 4. Atmospheric pressure distillation test method."

"Carbon content", "hydrogen content",

"carbon/hydrogen ratio", determined by JPI-5S-65-2004 "Test method for carbon, hydrogen, nitrogen and sulphur contents of petroleum products". The object of the measurements was residual oil after a 95% cut by ASTM distillation .

Normal paraffins of carbon number 21 or higher.

Obtained by calculating hydrocarbon contents for each carbon number from chromatograms obtained by using the gas chromatography method referred to in ASTM D 2887 "Standard test method for boiling range distribution of petroleum fractions by gas chromatography". In other words, an investigation was made of the retention times taking a mixture of normal paraffins of different carbon numbers as a standard sample, and the normal paraffins content was obtained from the total area peaks of the normal paraffins.

The type of column in the gas chromatography method was HP5 (length 30m; internal diameter 0.32 mm; film thickness 0.25 μπι) , and the analysis conditions were as follows: Column tank temperature rise conditions: 35°C (5 minutes), increased at a rate of 10°C/minute (temperature rise) to a final temperature of 320°C (11.5 minutes) . Sample volatilisation chamber conditions: Steady 320°C, split ratio 150: 1. Detector element: 320°C.

Sulphur content: Measured in accordance with JIS K

2541-4 "Crude oil and petroleum products - Determination of sulphur content Part 4: X-ray fluorescence method."

Aromatic content: Measured in accordance with JPI- 5S-49-97 "Petroleum products - Determination of

hydrocarbon types - High performance liquid

chromatography method."

Cetane index (new) : Measured in accordance with JIS K 2280 "Petroleum products - Determination of octane number, cetane number and calculation of cetane index 8. Calculation of cetane index of by the four-variable equation . "

Cetane index (old) : Means cetane index obtained in accordance with JIS K 2204-1992 "Diesel fuel."

Oil permeability: Referring to IP387/07, the test rig was a filter unit of diameter 90 mm. The filter was a membrane filter LSWP09025 (trade name: made by Merck Ltd) . Sample oil was passed through for one hour under conditions of oil temperature 13°C and flow rate 1.0 L/h, and the pressure values after oil had passed through were measured. If the pressure differential after passage of the oil exceeded 0.7 kg.cm2, this was recorded as "> 0.7". Given that the results of measurements for Fuel Oil "A" compositions at manufactured level where clogging of filters occurred in actual cases were in excess of 0.7 kg/cm2, this was taken as a standard and the oil

permeability was graded as a pass for 0.7 kg/cm2 and below .

Calorific value: Calculated in accordance with JIS K

2279 "Crude petroleum and petroleum products —

Determination and estimation of heat of combustion."

Table 2

Table 3

Claims

C L A I M S

1. A fuel oil composition comprising an FT derived oil, a cracked gas oil and a residual carbon adjusting component, wherein said fuel oil composition comprises a density of between 0.820 and 0.890 g/cm3, a residual oil carbon/hydrogen ratio after a 95% cut by ASTM

distillation of not more than 6.4, and a 10% residual oil carbon residue in excess of 0.20 mass%.

2. The fuel oil composition according to Claim 1 wherein the aromatic content is not less than 15.0 vol.% and the content of dicyclic or higher aromatics is not less than 5.0 vol.%.

3. The fuel oil composition according to Claim 1 or Claim 2 wherein the content of normal paraffins of carbon number 21 or higher is between 0.1 and 4.0 mass%.

4. The fuel oil composition according to any of Claims

1 to 3 wherein the content of the aforementioned FT derived oil is between 1.0 and 50.0 vol.% and the content of the aforementioned cracked gas oil is between 5.0 and 50 vol.%,

5. The fuel oil composition according to any of Claims

1 to 4 wherein the pressure difference before and behind a filter after oil is passed through a membrane filter for one hour under flow rate conditions of 1.0 L/h is not more than 0.7 kg/cm2.

6. Method of manufacture of a fuel oil composition in accordance with any of Claims 1 to 5 characterised in that it includes a process in which an FT derived oil, said FT derived oil having a density atl5°C of not less than 0.770 g/cm3 and normal paraffins of carbon number 21 or higher in the amount of between 2.0 and 10.0 mass%, and a cracked gas oil, having a density at 15°C of not less than 0.860 g/cm3, aromatic content of not less than 50.0 vol.% and a content of dicyclic or higher aromatics of not less than 40.0 vol.%, are mixed together.