Patent Application
20230002683
The present invention relates to stabilized fuel oils prepared by mixing two or more kinds of oil fractions such as asphaltene-containing oil fraction(s) and a high-saturated hydrocarbon oil fraction(s), particularly a process for preparation of stabilized fuel oil comprising mixing two or more kinds of oil fractions to obtain an oil mixture and filtering the oil mixture, and stabilized fuel oil obtained therefrom.
Crude oil is mainly composed of saturated hydrocarbons, aromatic hydrocarbons, resins and asphaltenes. These components exhibit different solubility from each other by their polarities, which in turn affect the stability of hydrocarbon oils produced by crude oil refining. The polarity of the components increases in the order of saturated hydrocarbons, aromatic hydrocarbons, resins, and asphaltenes.
Saturated hydrocarbons are nonpolar and the four components forming crude oil, namely saturated hydrocarbons, aromatic hydrocarbons, resins and asphalenes, differ in their affinity from each other. For example, saturated hydrocarbons and asphalenes are hardly mutually dissoluble due to their low affinity, whereas saturated hydrocarbons and aromatic hydrocarbons are mutually dissoluble due to their high affinity.
Asphaltenes, which have the greatest effect on the stability of hydrocarbon oils, is dispersed in hydrocarbon oils in a colloidal state of micelle structure stabilized by resins having both of polar and nonpolar functional groups.
When the stabilized micelle structure of asphaltenes is broken by changes in pressure, temperature and/or other external environments, asphaltenes aggregate into particles by strong intermolecular n-n bonds and eventually precipitate into a solid state.
Depending on the blending conditions of hydrocarbon oils and crude oil, the precipitation of asphaltenes may be intensified. Oil containing precipitated asphaltenes can cause the following problems: fouling and coke generation in pipings, heaters, heat exchangers and the like; clogging or blocking in combustion nozzles, filters, centrifuges, pipings and the like; and slurry generation in oil storage tanks, etc.
The oil refining process performs atmospheric distillation and/or vacuum distillation of crude oil to produce fuel oils such as naphtha, kerosene, diesel and the like. In order to further produce further fuel oils such as naphtha, kerosene, diesel, and the like from residue oil fractions obtained from atmospheric distillation or vacuum distillation, an upgrading process such as hydrocracking, pyrolysis, fluidized catalytic cracking, solvent extraction, hydrodesulfurization and the like may be performed. The residue oil fractions used as raw materials in the upgrading processes may be used in the preparation of atmospheric residue oil, vacuum residue oil, residue desulfurized oil, residue catalytic cracking oil, residue pyrolyzed oil, residue hydrocracking oil, residue solvent-extracted oil, pitch and the like.
When oil fractions (i.e., hydrocarbon oil fractions) produced from different processes are mixed and used as a raw material of the upgrading processes, problems such as precipitation, fouling, and plugging of asphaltenes may occur in a tank for mixing raw materials, a heater, a heat exchanger and the like.
As the International Marine Organization (IMO) regulates the sulfur content of over 0.5 weight % of marine fuel oils from 2020, refiners and marine fuel oil suppliers must produce low sulfur fuel oils and supply them as marine fuel oils. Low sulfur marine fuel oils that meet the IMO 2020 regulation can be produced by mixing high sulfur residue oils with oil distilled from crude oil. The distilled oil has very low sulfur content, because it undergoes the hydrodesulfurization process and is suitable as blending oil for the preparation of marine fuel oil. But, since the distilled oil is traded at a higher price than general marine fuel oil, it is not desirable to blend the distilled oil into the marine fuel oil. In addition, the distilled oil contains high levels of paraffinic or naphthenic saturated hydrocarbons having high non-polarity, making the stability of asphaltenes remarkably low, which can lead to precipitation of asphaltenes.
Alternatively, it may be possible to adopt a method of desulfurizing a high sulfur-containing residue oil to produce marine fuel oil that meet the IMO 2020 regulation. When residue oil fraction, in which components such as resins, aromatic compounds, saturated hydrocarbons and the like are in stable equilibrium with asphaltenes, is hydrodesulfurized to remove sulfur, double bonds present in the aromatic components and the resin components are hydrogenated and converted into saturated hydrocarbons. Due to the increase of the saturated hydrocarbons, the stable equilibrium state is transferred to an unstable state, thereby causing precipitation of asphaltenes. In addition, the low sulfur hydrocarbon oil produced through the hydrodesulfurization of residue oil fraction has a high content of saturated hydrocarbons, and thus acts as a factor that precipitates asphaltenes when mixed with asphaltene-containing hydrocarbon oil. Therefore, it is difficult to prepare asphaltene-stabilized fuel oil in this way.
Korean Patent No. 10-1886858 discloses a process for stabilization of heavy hydrocarbons to reduce sludge formation in storage tanks and/or transportation lines and to enhance the hydrocarbon yield including mixing a paraffinic or heavy naphtha solvent having carbon numbers in the range 10 to 20 with the feedstock to solvent-flocculate a relatively small, predetermined portion of asphaltenes present in the feedstock, separating and flashing the sediment to recover a light hydrocarbon fraction, flashing the heavy hydrocarbon/solvent phase and recycling the solvent to stabilize the heavy hydrocarbons without significantly affecting the yield of valuable products.
Therefore, there is a need for simple and effective producing of asphaltene-stabilized fuel oil.
According to one aspect of the present invention, there is provided a method for preparing an asphaltene-stabilized fuel oil which comprises: (i) mixing an asphaltene-containing oil fraction and a high-saturated hydrocarbon oil fraction to obtain a mixture of oil fractions; and (ii) filtering the oil fraction mixture through a filtering media to remove precipitates therein and recover the asphaltene-stabilized fuel oil.
The asphaltene-containing oil fractions include, but not limited to, any one selected from the group consisting of crude oil, atmospheric residue oil, vacuum residue oil, residue desulfurization oil, residue catalytic cracking oil, residue pyrolysis oil, residue hydrocracking oil, residue solvent extraction oil, pitch and mixtures of two or more thereof.
The high-saturated hydrocarbon oil fractions include, but not limited to, any one selected from the group consisting of distillates from crude oil, pyrolysis oils, catalytic cracking oils, hydrocracking oils, hydrodesulfurized oils, alkane oils and derivatives thereof, iso-alkane oils and derivatives thereof, cycloalkane oils and derivatives thereof, polycyclic naphthenic oils and derivatives thereof, and mixtures of two or more thereof.
The alkane oils may be selected from the group consisting of methane, ethane, propane, butane, pentane, heptane, heptane, octane and mixtures of two or more thereof. The iso-alkane oils may be selected from the group consisting of iso-propane, iso-butane, iso-pentane, iso-heptane, iso-heptane, iso-octane, and mixtures of two or more thereof. The cycloalkane oils may be selected from the group consisting of cyclopentane, cyclohexane, cycloheptane, cyclooctane, and mixtures of two or more thereof.
In the filtering step (ii), a filtering medium may have a mesh opening diameter of 0.1 to 20 μm.
In the filtering step (ii), the mixture may be filtered at a pressure difference between the upstream and downstream of the filtering medium of 1 mbar to 100 bar, and at a temperature of 30 to 200° C.
The method may further comprise a step of allowing the oil fraction mixture obtained in the mixing step (i) to stand before the filtering step (ii).
The standing step may be performed by leaving the oil fraction mixture stand for a period of 10 minutes to 72 hours at a temperature of 0 to 100° C. under atmospheric pressure.
According to another aspect of the present invention, there is provided an asphaltene-stabilized fuel oil prepared by the method which comprises; (i) mixing asphaltene-containing oil fractions and high-saturated hydrocarbon oil fractions to obtain a mixture of oil fractions; and (ii) filtering the mixture to remove the precipitate and recover the asphaltene-stabilized fuel oil.
Preferably, the asphaltene-stabilized fuel oil may have a sulfur content of not more than 0.5 weight %.
According to the present invention, a fuel oil having high stability can be produced by filtering a mixture obtained by mixing various oil fractions remaining after producing high quality oil in various processes of petroleum refining, particularly residue oils containing a high content of asphaltenes, such as residues from various processes, with high-saturated hydrocarbon oil fractions.
In particular, it is possible to solve the problem of leaching of asphaltenes occurred, when the asphaltene-containing oil fraction is mixed with other oil fractions, in particular high-saturated hydrocarbon fraction.
In addition, the yield is high and the production cost is lowered, since the fuel oil is produced in the asphaltene-stabilized state by filtering the oil fraction mixture. Also, the productivity of the fuel oil can be improved, because there are almost no restrictions on the source of the oil fractions, the mixing ratio of the oil fractions, etc.
A method for preparing an asphaltene-stabilized fuel oil according to the present invention comprises: (i) mixing asphaltene-containing oil fractions and high-saturated hydrocarbon oil fractions to obtain a mixture of oil fractions; and (ii) filtering the oil fraction mixture through a filtering medium to remove precipitates in the mixture and recover the asphaltene-stabilized fuel oil.
In efforts to produce high quality of the asphaltene-stabilized fuel oil and increase the yield of the fuel oil, inventors have made lots of experiments to produce fuel oil by mixing various residue oil fractions remaining after producing high quality oil in various processes of petroleum refining. Asphaltenes remaining in oil fractions, especially high asphaltene-containing oil fractions, tend to destabilize and precipitate, when mixed with high-saturated hydrocarbon oil fraction of high non-polarity. Even when a high-saturated hydrocarbon oil fraction is mixed with an oil fraction containing asphaltenes stably, there are possibilities that the micelle structure of asphaltenes present in the asphaltene-stabilized oil fraction is destroyed by the mixing operation, resulting in precipitation of separated or isolated asphaltenes.
Since high saturated hydrocarbon oil fractions such as distillates from crude oil have a high content of saturated hydrocarbons, the mixture obtained by mixing it with an asphaltene-containing oil fraction is disadvantageous for stabilizing asphaltenes. In particular, the oil fraction produced through the hydrocracking process has a higher saturated hydrocarbon content than the distilled oil fraction, which is more disadvantageous for stabilizing asphaltenes in the fuel oil. On the other hand, pyrolysis oil fractions or catalytic cracking oil fractions have a relatively high content of aromatic compounds, and the aromatic compounds have a higher affinity to asphaltenes than saturated hydrocarbons, which can help stabilize the asphaltene-containing oil fractions.
An asphaltene-free oil fraction such as oil fraction, from which asphaltenes have been removed by extracting with a C3, C5 or C7 solvent in the refinery process, is very suitable for a blending oil, but not suitable for a low sulfur fuel oil, because it contains large amounts of sulfur. The asphaltene-free oil is used as a raw material for the fluidized catalytic cracking process, following the pre-treatment such as desulfurization, denitrification, and demetallization processes for maintaining the performance of the catalyst used in the process.
The pre-treatment of raw materials in the fluidized catalytic cracking process, which involves hydrogenation, results in very low sulfur content of asphaltene-free oil, and causes the hydrogenation of aromatic or resin components, whereby the conversion to oil with very high saturated hydrocarbon content occurs. The asphaltene-free oil obtained through a desulfurization process is suitable for low sulfur fuel oil due to its low sulfur content, but not suitable for the production of fuel oil by mixing with asphaltene-containing oil fractions.
The inventors have found that in producing fuel oils by mixing various kinds of oil fractions, a stabilized fuel oil can be prepared by mixing an asphaltene-containing oil fraction and a high-saturated hydrocarbon oil fraction and then, filtering and stabilizing the mixture, and further, when the asphaltene-containing oil fraction is mixed with the high-saturated hydrocarbon oil fraction, some asphaltenes in the resulting mixture precipitate into aggregated solid particles as their stabilized equilibrium state is broken, and some asphaltenes are stably present in a colloidal state, equilibrating in the mixture, and then, by removing the precipitated asphaltenes from the mixture, asphaltene-stabilized fuel oil can be prepared. The asphaltenes precipitated as solids from the mixture of oil fractions can be filtered through a filter, and the oil fraction mixture passed through the filter is particularly suitable for use as marine fuel oil or other fuel oils.
The asphaltene-containing oil fractions include, but not limited to, any one selected from the group consisting of crude oil, atmospheric residue oils, vacuum residue oils, residue desulfurization oils, residue catalysis oils, residue pyrolysis oils, residue hydrocracking oils, residue solvent extraction oils, pitches, and mixtures of two or more thereof.
The high-saturated hydrocarbon oil fractions include, but not limited to, any one selected from the group consisting of distillates from crude oil refining, pyrolysis oils, catalytic cracking oils, hydrocracking oils, hydrodesulfurized oils, alkane oils and derivatives thereof, iso-alkane oils and derivatives thereof, cycloalkane oils and derivatives thereof, polycyclic naphthenic oils and derivatives thereof, and mixtures of two or more thereof.
The alkane oils may be selected from the group consisting of methane, ethane, propane, butane, pentane, heptane, heptane, octane, and mixtures of two or more thereof.
The iso-alkane oils may be selected from the group consisting of iso-propane, iso-butane, iso-pentane, iso-hexane, iso-heptane, iso-octane, and mixtures of two or more thereof.
The cycloalkane oil may be selected from the group consisting of cyclopentane, cyclohexane, cycloheptane, cyclooctane, and mixtures of two or more thereof.
Oil distilled from crude oils, pyrolysis oils, catalytic cracking oils, hydrocracking oils, and hydrodesulfurized oils may include naphtha, kerosene, diesel, unconverted oil and the like.
The filtering medium may desirably be one having a mesh opening diameter within the range of 0.1-20 μm. If the mesh opening diameter of the filtering medium is smaller than 0.1 μm, there may be a problem that the differential pressure between the upstream and downstream of the filtering medium increases beyond the need, thereby increasing the time and cost required to produce the asphaltene-stabilized fuel oil, and if it exceeds 20 μm, there may be a problem that the precipitated asphaltenes may pass through the filtering medium without being removed by the filter, resulting in insufficient asphaltene-stabilization of the fuel oil obtained.
Various tests have shown that the desirable filtration temperature ranges from −20 to 400° C. and preferably from 30 to 200° C. If the filtration temperature is less than −20° C., the flowability of the mixture of oil fractions may be reduced, and the filtering medium may become clogged as the wax content of the mixture of oil fractions has been crystallized. If the filtration temperature exceeds 400°, the oil fractions contained in the mixture may evaporate and decompose, thereby varying the composition of the mixture.
Filtering pressure is not particularly limited. Preferably, the pressure difference between the upstream and downstream of the filtering medium is between 1 mbar and 100 bar. If the pressure difference is too low, the filtration performance may not be good. The method for producing stabilized fuel oil according to the present invention may further comprise standing of the oil fraction mixture obtained from the mixing step between the mixing step and the filtrating step.
The standing step may be performed by leaving the oil fraction mixture obtained from the mixing step stand for 10 to 72 hours at a temperature range of 0 to 100° C. and, preferably, 30 to 70° C. and under atmospheric pressure.
By such standing of the oil fraction mixture, asphaltenes contained in the oil fraction mixture is effectively settled at the bottom of the mixture, thereby improving filtration efficiency in the subsequent filtering step, and prolonging the life of the filter.
Hereinafter, the present invention will be described in detail by way of examples.
Hydrocarbon oil (t-AR: treated atmospheric residue) obtained from the desulfurization of atmospheric residue oil was used as an asphaltene-containing oil fraction. Hydrocarbon oil (t-DAO: treated de-asphalted oil) obtained from the hydrocracking of hydrocarbon oil (DAO: de-asphalted oil) from which asphaltenes are extracted and removed by n-pentane solvent was used as a high-saturated hydrocarbon oil fraction. The asphaltene-containing oil fraction and the high-saturated hydrocarbon oil fraction were mixed at the mixing ratios shown in Table 1 below.
The resulting mixture was filtered using three filtering media having mesh opening diameters of 5 μm, 8 μm and 11 μm, respectively to remove asphaltenes and obtain fuel oils. During filtering step, the temperature was maintained at 70° C. and the pressure difference between the upstream and downstream of the filtering media was 1 bar.
The obtained fuel oils were evaluated for their stability according to the ASTM D 4740-02 test method. The results are shown in Table 1 below.
The t-AR was filtered using filtering media having mesh opening diameters of 5 μm, 8 μm and 11 μm, respectively to remove asphaltenes and obtain fuel oils. During filtration, the temperature was maintained at 70° C. and the pressure difference between the upstream and downstream of the filtering media was 1 bar. The obtained fuel oils were evaluated for its stability according to the ASTM D 4740-02 test method. The results are shown in Table 1 below.
Atmospheric residue (WTI-AR) produced from light crude oil from Texas was used as an asphaltene-containing oil fraction. Hydrocracking gas oil (HCGO) was used as a high-saturated hydrocarbon oil fraction. The asphaltene-containing oil fraction and the high-saturated hydrocarbon oil fraction were mixed at the mixing ratios shown in Table 1 below. The resulting oil fraction mixture was filtered using three filtering media having mesh opening diameters of 5 μm, 8 μm and 11 μm, respectively to remove asphaltenes and obtain fuel oils. During filtration, the temperature was maintained at 70° C. and the pressure difference between the upstream and downstream of the filtering media was 1 bar.
The obtained fuel oils were evaluated for their stability according to the ASTM D 4740-02 test method. The results are shown in Table 1 below.
The WTI-AR was filtered using filtering media having mesh opening diameters of 5 μm, 8 μm and 11 μm, respectively to remove asphaltene and obtain fuel oils. During filtration, the temperature was maintained at 70° C. and the pressure difference between the upstream and downstream of the filtering media was 1 bar. The obtained fuel oils were evaluated for stability according to the ASTM D 4740-02 test method. The results are shown in Table 1 below.
Hydrocarbon oil (t-AR: treated atmospheric residue) obtained from the desulfurization of atmospheric residue oil, slurry oil (SLO) produced from the fluidized catalytic cracking (FCC) of atmospheric residue oil, light cycle oil (LCO) produced from the fluidized catalytic cracking (FCC) of atmospheric residue oil, and C9+ heavy aromatic solvent (H-Aro) (heavy fraction left on the bottom of the distillation tower by the separation of xylene in the BTX production process) were mixed at the mixing ratios shown in Table 2 below.
The resulting oil fraction mixture was filtered using three filtering media having mesh opening diameters of 5 μm, 8 μm and 11 μm, respectively at 70° C. to remove asphaltenes and obtain a fuel oil. The obtained fuel oils were was evaluated for their stability according to the ASTM D 4740-02 test method. The results are shown in Table 2 below.
T-AR, SLO, LCO and H-Aro were mixed at the mixing ratios shown in Table 3 below.
The resulting oil fraction mixture was filtered through a filtering medium having a mesh opening diameter of 5 μm to remove asphaltenes and obtain a fuel oil. During filtration, the temperature was maintained at 70° C. and the pressure difference between the upstream and downstream of the filtering medium was 1 bar. The obtained fuel oil was evaluated for stability according to the ASTM D 4740-02 test method. The results are shown in Table 3 below.
T-AR, SLO, LCO and H-Aro were mixed at the mixing ratios shown in Table 3 below.
The resulting oil fraction mixture was filtered through a filtering medium having a mesh opening diameter of 5 μm to remove asphaltenes and obtain a fuel oil. During filtration, the temperature was maintained at 50° C. and the pressure difference between the upstream and downstream of the filtering medium was 1 bar. The obtained fuel oil was evaluated for its stability according to the ASTM D 4740-02 test method. The result is shown in Table 3 below.
T-AR, SLO, LCO and H-Aro were mixed at the mixing ratios shown in Table 3 below.
The resulting oil fraction mixture was filtered through a filtering medium having a mesh opening diameter of 5 μm to remove asphaltenes and obtain a fuel oil. During filtration, the temperature was maintained at 100° C. and the pressure difference between the upstream and downstream of the filtering medium was 1 bar. The obtained fuel oil was evaluated for its stability according to the ASTM D 4740402 test method. The result is shown in Table 3 below.
From the results shown in Tables 1 to 3, the following effects are demonstrated:
In the above examples, the mixed oil using t-AR and t-DAO as the asphaltene-containing oil fractions has been described, but it should be understood that similar results can be obtained for other asphaltene-containing oil fractions remaining after the production of high quality oil.
While the present invention has been described with reference to specific embodiments, various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the claims below, but also by the equivalents of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2019-0161976 | Dec 2019 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2020/005521 | 4/27/2020 | WO |
