METHOD OF PREPARING STABILIZED FUEL OIL AND THE SAME PRODUCED THEREFROM

Abstract

The present invention relates to a process for preparing an asphaltene-stabilized fuel oil comprising (i) mixing an asphaltene-containing oil fraction(s) and a high-saturated hydrocarbon oil fraction(s) to obtain a mixture of oil fractions; and (ii) filtering the obtained mixture through a filtering medium, and the asphaltene-stabilized fuel oil obtained therefrom.

Claims

1. A method for preparing an asphaltene-stabilized fuel oil, comprising: (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 medium to remove precipitates therein and recover the asphaltene-stabilized fuel oil.

2. The method according to claim 1, wherein the asphaltene-containing oil fraction is 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.

3. The method according to claim 1, wherein the high-saturated hydrocarbon oil fraction is selected from the group consisting of oil distilled from crude oil, pyrolysis oil, catalytic cracking oil, hydrocracking oil, hydrodesulfurized oil, alkane oil and derivatives thereof, iso-alkane oil and derivatives thereof, cycloalkane oil and derivatives thereof, polycyclic naphthenic oil and derivatives thereof, and mixtures of two or more thereof.

4. The method according to claim 3, wherein the alkane oil is selected from the group consisting of methane, ethane, propane, butane, pentane, heptane, heptane, octane, and mixtures of two or more thereof.

5. The method according to claim 3, wherein the iso-alkane oil is 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.

6. The method according to claim 3, wherein the cycloalkane oil is selected from the group consisting of cyclopentane, cyclohexane, cycloheptane, cyclooctane, and mixtures of two or more thereof.

7. The method according to claim 1, wherein the filtering medium has a mesh opening diameter of 0.1 to 20 μm.

8. The method according to claim 1, wherein in the filtering step (ii), the mixture is filtered at a pressure difference between the upstream and downstream of the filtering medium of 1 mbar to 100 bar, and a temperature of 30 to 200° C.

9. The method according to claim 1, further comprising standing of the oil fraction mixture obtained in the mixing step (i) before the filtering step (ii).

10. The method according to claim 9, wherein the standing step is 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 the atmospheric pressure.

11. An asphaltene-stabilized fuel oil prepared by the method according to claim 1.

12. The asphaltene-stabilized fuel oil according to claim 11, wherein the fuel oil has a sulfur content of 0.5 weight % or less.

Description

MODE FOR THE INVENTION

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The cycloalkane oil may be selected from the group consisting of cyclopentane, cyclohexane, cycloheptane, cyclooctane, and mixtures of two or more thereof.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Hereinafter, the present invention will be described in detail by way of examples.

Examples 1 to 3

[0044] 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.

[0045] 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.

[0046] 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.

Comparative Example 1

[0047] 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.

Examples 4 to 6

[0048] 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.

[0049] 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.

Comparative Example 2

[0050] 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.

TABLE-US-00001 TABLE 1 Asphaltene S.R. (1-5) content Mixing Before After filtering Raw materials (wt. %) ratio (wt. %) filtering 11 μm 8 μm 5 μm C. t-AR 5.15 100 4 4 4 1 Ex. 1 t-DAO — 0 Ex. 1 t-AR 5.15- 90 5 5 4 1 t-DAO — 10 Ex. 2 t-AR 5.15 70 5 2 2 1 t-DAO — 30 Ex. 3 t-AR 5.15 50 5 2 2 1 t-DAO — 50 C. WTI-AR 0.20 100 1 1 1 1 Ex. 2 HCGO — 0 Ex. 4 WTI-AR 0.20 90 1 1 1 1 HCGO — 10 Ex. 5 WTI-AR 0.20 70 1 1 1 1 HCGO — 30 Ex. 6 WTI-AR 0.20 50 2 2 2 1 HCGO — 50

Examples 7 and 8

[0051] 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.

[0052] 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.

TABLE-US-00002 TABLE 2 Asphaltene S.R. (1-5) content Mixing Before After filtering Raw materials (wt. %) ratio (wt. %) filtering 11 μm 8 μm 5 μm Ex. 7 t-AR 5.15 70 2 2 2 1 SLO — 10 LCO — 10 H-Aro — 10 Ex. 8 t-AR 5.15 80 3 3 3 1 SLO — 3 LCO — 12 H-Aro — 5

Example 9

[0053] T-AR, SLO, LCO and H-Aro were mixed at the mixing ratios shown in Table 3 below.

[0054] 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.

Example 10

[0055] T-AR, SLO, LCO and H-Aro were mixed at the mixing ratios shown in Table 3 below.

[0056] 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.

Example 11

[0057] T-AR, SLO, LCO and H-Aro were mixed at the mixing ratios shown in Table 3 below.

[0058] 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.

TABLE-US-00003 TABLE 3 S.R. (1-5) Asphaltene Mixing Filtration After Filtration Raw content Ratio Temp. Before filtering Time materials (wt. %) (wt. %) (° C.) filtering (5 μm) (min.) Ex. t-AR 5.15 70 70 2 1 10 9 SLO — 10 LCO — 10 H-Aro — 10 Ex. t-AR 5.15 80 50 2 1 30 10 SLO — 3 LCO — 12 H-Aro — 5 Ex. t-AR 5.15 70 100 2 1  5 11 SLO — 10 LCO — 10 H-Aro — 10

[0059] From the results shown in Tables 1 to 3, the following effects are demonstrated: [0060] The fuel oils obtained by filtering the oil mixture of the asphaltene-containing oil fraction and the high-saturated hydrocarbon oil fraction were all greatly improved in stability. [0061] The stability of the mixture of asphaltene-containing oil fraction and high-saturated hydrocarbon oil fraction was slower than that of asphaltene-containing oil alone (see comparative example 1 and example 1, and comparative example 2 and example 6). However, the stability of the oil fraction mixture after filtration was improved compared to the stability of the oil fraction mixture before filtration. [0062] The stability of the oil mixture of asphaltene containing oil fraction(s) and high-saturated hydrocarbon oil fraction(s) was higher as the mesh opening diameters of the filtering medium is smaller. In particular, among the filtering media used in the experiments, the stability was most improved when the 5 om filtering medium is used. [0063] Even when an asphaltene-containing oil fraction and two or more kinds of hydrocarbon oil fractions were mixed, the stability of the resulting mixture was improved by filtration through the filtering medium. In particular, the stability is improved when the filtering medium had the mesh opening diameter of 5 μm. [0064] Even when an asphalten-containing oil fraction and hydrocarbon oil fractions having high aromatic content were mixed, the resulting mixture was still unstable, but was converted to an asphalten-stabilized fuel oil by filtration. [0065] As the filtration temperature increased, the flowability of the oil fraction mixture increased, thereby increasing the filtration rate. The filtration time, which was 30 minutes at 50° C. (Example 10), was shortened to 10 minutes at 70° C. (Example 9) and 5 minutes at 100° C. (Example 11). Even if when the temperature was higher than 100° C., there is was no significant change in the filtration rate. In consideration of the time for heating, energy consumption, etc. as a whole, the filtration temperature was preferably 30 to 70° C. [0066] Among the filtering media used in the examples for all oil fraction mixtures, the 5 μm filtering medium could improve the stability of the mixture most (Spot Rating 1).

[0067] 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.

[0068] 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.