KR20210121723A - Desulfurization method of heavy oil using supercritical extraction - Google Patents

Abstract

The present invention relates to a method for desulfurizing heavy oil using supercritical extraction, and more specifically, to a method for desulfurizing heavy oil, wherein a hydrocarbon solvent is added to heavy oil containing a sulfur-containing compound to extract and separate the sulfur-containing compound from the heavy oil under supercritical conditions so that desulfurized heavy oil is obtained without the use of separate hydrogen and catalysts, the production ratio of by-products is lower than that of an existing process to improve economical efficiency and profitability, hydrogen sulfide is not generated during the process to be eco-friendly, and a process configuration is simple compared to previous technology to improve the efficiency of the process.

Description

Desulfurization method of heavy oil using supercritical extraction {Desulfurization method of heavy oil using supercritical extraction}

The present invention relates to a heavy oil desulfurization method using supercritical extraction, and more particularly, by adding a hydrocarbon solvent to the heavy oil containing a sulfur-containing compound, extracting and separating the sulfur-containing compound from the heavy oil under supercritical conditions. While obtaining desulfurized heavy oil without using hydrogen and catalyst of It relates to a method of desulfurization of heavy oil that can improve the efficiency of the process by being simple compared to the present invention.

Petroleum refining can be largely divided into simple refining and advanced refining. Simple refining usually separates and produces petroleum products by heating crude oil to more than 360 degrees Celsius and using the difference in boiling temperature of the components contained in crude oil. A typical example is an atmospheric distillation facility [Atmospheric Distillation Unit or Crude Distillation Unit (ADU/CDU)]. The principle is that when crude oil is put into a large tank and boiled, each component contained in the crude oil becomes gas and climbs up a large chimney. When crude oil that has become steam is cooled in the middle, petroleum products such as propane, butane, naphtha, kerosene, light oil, and bunker C oil come out in order according to the boiling point and molecular weight. In the case of simple refining, although it depends on the physical properties of crude oil, about 40 to 50% of bunker C oil, which is usually a heavy oil, comes out.

The advanced refining process is a process to produce gasoline, kerosene, diesel, and low-sulfur bunker C oil through processes such as processing, decomposition and desulfurization once again using high-sulfur bunker C oil as a raw material.

The advanced refining process is further divided into a heavy oil cracking process and a heavy oil desulfurization process.

The heavy oil cracking process is a process to produce gasoline, kerosene, and diesel by causing a chemical reaction with high sulfur bunker C oil using hydrogen and a catalyst. In detail, it is divided into hydrocracking and catalytic cracking. Hydrocracking is the process of decomposing heavy oil by adding hydrogen in high-temperature and high-pressure catalysis to produce naphtha, kerosene, and light oil. It is called HCR (Hydrocracking). Catalytic cracking produces gasoline and propylene by contacting heavy oil under a high-temperature catalyst. It is called RFCC (Residue Fluidized Catalytic Cracking). should be supplied.

Heavy oil desulfurization process is a process to remove various impurities contained in high sulfur bunker C oil to produce low sulfur bunker C oil and raw material oil for RFCC or HCR. Due to global environmental regulations, the supply shortage of low-sulfur petroleum products is deepening, and marketability is increasing.

West Texas Intermediate (WTI), which is one of the world's three largest crude oils, has a relatively high production rate of high-quality gasoline due to its high production cost but low sulfur content, but is more expensive than other types of oil. On the other hand, Dubai oil, which accounts for more than 70% of Korea's crude oil import, is cheaper than West Texas crude, but has a relatively high sulfur content and therefore high processing cost.

The heavy oil desulfurization process generally uses a resid hydrodesulfurization process (RDS) in which a liquid raw material and an excess of hydrogen are simultaneously introduced into the upper part of the reactor using a fixed-bed catalytic reactor.

However, the resid hydrodesulfurization process consumes a lot of hydrogen and catalyst, and because it is operated under high temperature and high pressure conditions, economic efficiency and profitability may be lowered. Because the compressor is essential, it is difficult to increase the efficiency of the process. In addition, the ratio of by-products such as gas, naphtha, and diesel generated in the resid hydrodesulfurization process is as high as 20% or more, and there is also a problem that the cracking reaction caused by the use of hydrogen cannot be avoided. do. Furthermore, hydrogen sulfide is generated in the desulfurization process, which is not environmentally friendly.

In addition, the sulfur component remaining in the hydrodesulfurized 　 atmospheric residue (t-AR, hydrotreated atmospheric residue) through the RDS process remains in a form that is very difficult to further desulfurize due to its molecular structure. It is very difficult to commercialize 0.3 BC (bunker oil content below 0.3 wt% 　) by lowering the sulfur content by performing

Therefore, it is possible to obtain desulfurized heavy oil without using separate hydrogen and catalyst, and improve economic efficiency and profitability due to a low production rate of by-products compared to the existing process, and it is environmentally friendly because hydrogen sulfide is not generated during the process, and the process configuration There is a need to develop a method for desulfurization of heavy oil that is simpler than the previous technology and can improve the efficiency of the process.

The present invention is to solve the problems of the prior art, by adding a hydrocarbon solvent to the heavy oil containing the sulfur-containing compound, extracting and separating the sulfur-containing compound from the heavy oil under supercritical conditions, thereby producing a separate hydrogen and catalyst While obtaining desulfurized heavy oil without using it, the production rate of by-products is lower than in the existing process, so economical efficiency and profitability can be improved. It is a technical task to provide a method for desulfurization of heavy oil that can improve the efficiency of

In order to achieve the above technical problem, the present invention is a first step of extracting and separating the sulfur-containing compound from the heavy oil under supercritical conditions by adding a hydrocarbon solvent to the heavy oil containing the sulfur-containing compound; a second step of separating a hydrocarbon solvent from the heavy oil from which the sulfur-containing compound has been removed in the first step to obtain a desulfurized heavy oil; and a third step of reusing the hydrocarbon solvent separated in the second step by transferring it to the first step, wherein hydrogen and a catalyst are not used in the first step and the second step, and a desulfurization method of heavy oil is provided.

By using the heavy oil desulfurization method of the present invention, desulfurized heavy oil is obtained without using separate hydrogen and a catalyst, and the production rate of by-products is lower than in the existing process, and the reduction rate of sulfur in the heavy oil without hydrogen sulfide generated during the process It is eco-friendly, economical and profitable as it can secure up to 60% of In addition, since it has a relatively simple process configuration compared to the conventional hydrodesulfurization process, it is possible to process the heavy oil in the overall oil refining process such as AR, VR, and t-AR as a single unit, thereby improving the efficiency of the process. .

In particular, the sulfur component remaining in the hydrodesulfurized 　 desulfurized atmospheric residue (t-AR, hydrotreated atmospheric residue) through the RDS process exists in a form that is difficult to further desulfurize, but when using the desulfurization method of the present invention, the sulfur content is lowered. 0.3 BC (sulphur content 　 0.3 wt% 　 or less bunker oil) can be commercialized, and energy consumption can be reduced compared to the existing RDS process, which consumes a lot of hydrogen and energy for additional desulfurization.

The heavy oil desulfurization method of the present invention may be performed alone or may be used in conjunction with a conventional hydrodesulfurization process. Desulfurization can also be carried out in conditions much milder than operating conditions.

1 schematically shows the heavy oil desulfurization method of the present invention.

Hereinafter, the present invention will be described in more detail.

The heavy oil desulfurization method of the present invention includes a first step of extracting and separating the sulfur-containing compound from the heavy oil under supercritical conditions by adding a hydrocarbon solvent to the heavy oil containing the sulfur-containing compound; a second step of separating a hydrocarbon solvent from the heavy oil from which the sulfur-containing compound has been removed in the first step to obtain a desulfurized heavy oil; and a third step of reusing the hydrocarbon solvent separated in the second step by transferring it to the first step, characterized in that hydrogen and a catalyst are not used in the first step and the second step.

As used herein, the term “sulfur-containing compound” refers to a compound in which sulfur in heavy oil is intensively distributed, and may be, for example, asphaltene, heavy resin, polyaromatic compound, or a combination thereof.

In addition, in the present specification, "heavy oil from which sulfur-containing compounds are removed" means that the sulfur content in the heavy oil is 5.0% by weight or less, for example, 4.5% by weight or less, 4.0% by weight or less, 3.5% by weight or less, 3.0% by weight or less, 2.5% by weight or less. % or less, 2.0 wt% or less, 1.5 wt% or less, 1.0 wt% or less, 0.8 wt% or less, 0.5 wt% or less, 0.4 wt% or less or 0.3 wt% or less.

The heavy oil desulfurization method of the present invention includes a first step of extracting and separating the sulfur-containing compound from the heavy oil under supercritical conditions by adding a hydrocarbon solvent to the heavy oil containing the sulfur-containing compound.

The hydrocarbon solvent used in the present invention may be a hydrocarbon solvent having 4 to 6 carbon atoms, for example, n-butane, i-butane, n-pentane, i-pentane, n-hexane, i-hexane, and combinations thereof. One selected from the group consisting of can be used, for example, n-pentane can be used. By adding such a hydrocarbon solvent to heavy oil to extract and separate sulfur-containing compounds under supercritical conditions, the desulfurization process can be performed without requiring a large amount of hydrogen and a catalyst as in the hydrodesulfurization process.

The heavy oil containing the sulfur-containing compound of the first step is, atmospheric residue (AR, Atmospheric Residue), vacuum residue (VR, Vacuum Residue), desulfurization atmospheric residue (t-AR, hydrotreated Atmospheric Residue), desulfurization and reduced pressure It may be selected from the group consisting of residue oil (t-VR, hydrotreated vacuum residue), deasphalted oil (DAO), vacuum gas oil (VGO, vacuum gas oil), and combinations thereof. For example, a heavy oil comprising a sulfur containing compound may be AR, VR or t-AR.

In the heavy oil desulfurization method of the present invention, the first step may be performed at a pressure of 35 to 50 bar and supercritical conditions of 190 to 250°C. The sulfur-containing compound contained in the heavy oil under supercritical conditions may be extracted and separated into the hydrocarbon solvent described above. The lower limit of the pressure condition may be 35 bar or more, 36 bar or more, 38 bar or more, or 40 bar or more, and the upper limit may be 50 bar or less, 49 bar or less, or 48 bar or less, and the pressure range is, for example, 35 to 50 bar, 36 to 50 bar, 38 to 49 bar or 40 to 48 bar. The lower limit of the temperature condition may be 190 °C or higher, 192 °C or higher, 195 °C or higher, 198 °C or higher, or 200 °C or higher, and the upper limit is 250 °C or lower, 245 °C or lower, 240 °C or lower, 235 °C or lower, or 230 °C or lower. and the temperature range may be, for example, 190 to 250 °C, 192 to 245 °C, 195 to 240 °C, 198 to 235 °C, or 200 to 230 °C. When the pressure and temperature ranges are out of the above ranges, the extraction and separation of sulfur-containing compounds may be lowered, and thus the reduction of the sulfur content in the heavy oil may be poor.

Although not particularly limited, the amount of the hydrocarbon solvent added in the first step may be 100 to 500% by volume, 200 to 450% by volume, or 250 to 400% by volume based on 100% by volume of the heavy oil. If the hydrocarbon pressure and temperature range is out of the above range, the extraction and separation of sulfur-containing compounds may be lowered, and thus the reduction of the sulfur content in the heavy oil may be poor.

In addition, the extracted sulfur-containing compounds may be removed as a pitch stream in the extraction column.

In the second step of the heavy oil desulfurization method of the present invention, the hydrocarbon solvent is separated from the heavy oil from which the sulfur-containing compound has been removed in the first step to obtain a desulfurized heavy oil. Separation of hydrocarbons may be performed by volatilizing a mixture of desulfurized heavy oil and a hydrocarbon solvent, but is not limited thereto. In addition, although not particularly limited, the sulfur content of the desulfurized heavy oil is 5.0 wt% or less, for example, 4.5 wt% or less, 4.0 wt% or less, 3.5 wt% or less, 3.0 wt% or less, 2.5 wt% or less, 2,0 wt% or less % or less, 1.5 wt% or less, 1.0 wt% or less, 0.8 wt% or less, 0.5 wt% or less, 0.4 wt% or less, or 0.3 wt% or less.

In the third step of the heavy oil desulfurization method of the present invention, the hydrocarbon solvent separated in the second step is transferred to the first step and reused. Reusing hydrocarbon solvents can improve the economics and profitability of the process.

The heavy oil desulfurization method of the present invention does not use hydrogen and a catalyst as in the conventional hydrodesulfurization process in the first and second steps. The production rate of by-products is lower than that of the existing process while obtaining desulfurized heavy oil without the use of separate hydrogen and catalyst, and hydrogen sulfide is not generated during the process. have.

In particular, the sulfur component remaining in the hydrodesulfurized 　 desulfurized atmospheric residue (t-AR, hydrotreated atmospheric residue) through the RDS process exists in a form that is difficult to further desulfurize, but when using the desulfurization method of the present invention, the sulfur content is lowered. 0.3 BC (sulphur content 　 0.3wt% 　 or less bunker oil) can be commercialized, and energy consumption can be reduced compared to the existing RDS process, which consumes a lot of hydrogen and energy for additional desulfurization.

The heavy oil desulfurization method of the present invention may be performed alone or in conjunction with an existing hydrodesulfurization process. For example, in the case of performing additional desulfurization of the residual oil that has undergone hydrodesulphurization, desulfurization can be performed even under conditions much milder than the operating conditions of the existing hydrodesulfurization process.

Hereinafter, the present invention will be described in more detail through Examples and Comparative Examples. However, the scope of the present invention is not limited by these examples.

[Example]

Example 1

t-AR (sulfur content: 0.51 wt %) was added to 300 vol % of n-pentane, a hydrocarbon solvent, with respect to 100 vol % of the raw heavy oil, and asphaltene, a sulfur-containing compound, was obtained at 220 ° C. and 46 barg, which are supercritical conditions. Extracted and isolated. A hydrocarbon solvent was separated from the asphaltene-free heavy oil to obtain a desulfurized heavy oil. The sulfur content of the desulfurized heavy oil was 0.20 wt%, the reduction rate of the sulfur content compared to the raw material was 60%, and the obtained heavy oil yield was 96 wt%.

Example 2

VR (sulfur content: 5.5 wt %) was added to 100 vol % of the raw heavy oil, and 300 vol % of n-pentane, a hydrocarbon solvent, was added to extract asphaltene, a sulfur-containing compound, at 200 ° C. and 46 barg, which are supercritical conditions, and separated. A hydrocarbon solvent was separated from the asphaltene-free heavy oil to obtain a desulfurized heavy oil. The sulfur content of the desulfurized heavy oil was 2.5 wt%, the reduction rate of the sulfur content compared to the raw material was 55%, and the obtained heavy oil yield was 80 wt%.

Example 3

A mixed heavy oil of 70% AR and 30% VR (sulfur content: 5% by weight) was added to 100% by volume of the raw heavy oil, and 300% by volume of n-pentane, a hydrocarbon solvent, was added, at 200° C. and 46 barg, which are supercritical conditions. Asphaltene, a sulfur-containing compound, was extracted and isolated. A hydrocarbon solvent was separated from the asphaltene-free heavy oil to obtain a desulfurized heavy oil. The sulfur content of the desulfurized heavy oil was 3.5% by weight, the reduction rate of the sulfur content compared to the raw material was 30%, and the obtained heavy oil yield was 85% by weight.

Comparative Example 1

AR (sulfur content: 4.0 wt %) was added to the reactor as a raw material heavy oil, and the hydrodesulfurization process was performed under operating conditions of the reactor at 160 barg and 400 °C. At this time, the hydrogen consumption participating in the desulfurization reaction is 150 Nm ³ H ₃ /m ³ , which is 13.4 kg of hydrogen consumed per ^{1 m 3 of the raw material.}

The amount of hydrogen that participates in the reaction and is used for temperature control is supplied as a surplus, which is five times the amount of hydrogen consumed in the desulfurization reaction, which causes an increase in the capacity of the compressor and excessive operating costs.

As for the desulfurization performance of this hydrodesulfurization process, the sulfur content of t-AR obtained as a product is 0.8 wt%, and the sulfur content reduction rate is 80%, which is relatively high, but the energy consumption to meet the reactor operating conditions is large and , it can be confirmed that the input hydrogen and catalyst are too much, and hydrogen sulfide is generated in the desulfurization process, so economical efficiency and eco-friendliness are poor.

As can be seen from the above Examples and Comparative Examples, the heavy oil desulfurization method of the present invention can more economically obtain desulfurized heavy oil without using excess hydrogen and catalyst. In particular, the heavy oil desulfurization method of the present invention can be used in conjunction with the existing hydrodesulfurization process, for example, in the case of performing additional desulfurization of the residual oil that has undergone hydrodesulphurization, it is much milder than the operating conditions of the existing hydrodesulfurization process. Desulfurization can also be performed under conditions.

Claims (8)

A first step of extracting and separating the sulfur-containing compound from the heavy oil under supercritical conditions by adding a hydrocarbon solvent to the heavy oil containing the sulfur-containing compound;
a second step of separating a hydrocarbon solvent from the heavy oil from which the sulfur-containing compound has been removed in the first step to obtain a desulfurized heavy oil; and
It includes a third step of reusing the hydrocarbon solvent separated in the second step by transferring it to the first step,
No hydrogen and catalyst are used in the first and second steps,
Desulfurization method of heavy oil. According to claim 1, wherein the hydrocarbon solvent is a hydrocarbon solvent having 4 to 6 carbon atoms, heavy oil desulfurization method. The method of claim 2, wherein the hydrocarbon solvent is selected from the group consisting of n-butane, i-butane, n-pentane, i-pentane, n-hexane, i-hexane, and combinations thereof. According to claim 1, wherein the heavy oil containing a sulfur-containing compound,
A method for desulfurization of heavy oil, selected from the group consisting of atmospheric residue, vacuum residue, desulfurization atmospheric residue, desulfurization vacuum residue, deasphalted oil, vacuum gas oil, and combinations thereof. According to claim 1, wherein the first step is carried out under the conditions of a pressure of 35 to 50 bar and 190 to 250 ℃,
Desulfurization method of heavy oil. The method according to claim 1, wherein the sulfur-containing compound is asphaltene, a heavy resin, a polycyclic aromatic compound, or a combination thereof. The method according to claim 1, wherein the sulfur content of the desulfurized heavy oil is 5.0% by weight or less. A heavy oil obtained by the method of any one of claims 1 to 7.

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