JP2001247876A - Process and apparatus for separating and recovering organosulfur compound from liquid oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple process for removing and recovering organosulfur compounds from a fuel oil at a low energy consumption and a low cost without the necessity for high temperatures, high pressures, and an expensive catalyst and without producing a large quantity of carbon dioxide. SOLUTION: This process comprises adding a highly polar solvent to a liquid oil containing organosulfur compounds to migrate the organosulfur compounds to the solvent; further adding water if there is little difference between the specific gravity of the solvent and that of the liquid oil; and recovering the organosulfur compounds in the state in which they retain their initial chemical structures.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for separating at least an organic sulfur compound from a liquid oil such as petroleum and recovering the separated organic sulfur compound.

[0002]

2. Description of the Related Art Conventionally, sulfur has been removed from fuel oils such as light oil, kerosene, gasoline, heavy oil, and coal liquefied oil.
Generally, a hydrogen reduction desulfurization method is employed. That is, regarding the separation and removal of organic sulfur compounds from liquid oil, the liquid oil and hydrogen gas are reacted using a catalyst under severe reaction conditions of high temperature and high pressure to remove the organic sulfur compounds contained in the liquid oil. It is a technology that converts it into toxic hydrogen sulfide for separation.

[0003] Liquid oil contains substances such as organic sulfur compounds and aromatic hydrocarbon compounds. If the liquid oil is used as fuel and burned while containing these substances, , harmful substances are generated for SO _X, soot, SPM, such as NO _X organism, by discharging these substances in the outside air, harmful substances such as harmful carcinogens in human body airborne environmental And the quality of liquid oil products such as petroleum immediately becomes all environmentally relevant.

Conventionally, a method for removing sulfur from fuel oil is disclosed in Japanese Patent Application Laid-Open No. 4-72387. The method of removing sulfur from the fuel oil is to oxidize the fuel oil obtained from petroleum and coal liquefied oil using an oxidizing agent to raise the boiling point of the organic sulfur compound contained therein, and To separate and remove the organic sulfur compound from the organic solvent.

[0005] Further, as a refining technology of a fuel oil using a solvent, there is one disclosed in Japanese Patent Application Laid-Open No. 7-197636. A method for removing sulfur from the fuel oil is to mix a catalyst having a low solubility in hydrocarbons and a high solubility in organic sulfur compounds with the fuel oil and to form a lone electron pair on a divalent sulfur atom of the sulfur-containing functional group. The organic sulfur compound is transferred into the above-mentioned solvent by utilizing the nucleophilicity of the above, and the organic sulfur compound is separated and recovered from the fuel oil by sedimentation, permeation, filtration and / or centrifugation. Further, in the method, the solvent used to extract the organic sulfur compound from the liquid oil is acetone, methanol, acetonitrile,
One or several substances selected from pyridine, N'N-dimethylformamide, N-methylpyrrolidinone, trimethylphosphoramide, hexamethylphosphoramide, etc., or water mixed with the above substance in a concentration range of 20% or less. It is selected from a mixture.

[0006]

However, SO _X , N
Acid rain is generated by the discharge into the atmosphere of the acid gas O _X such, it believed to adversely affect the human body and the natural environment as one of its important causes, petroleum, coal, etc. fuel oil of Organic sulfur compounds have been pointed out, and the recent improvement in the quality of liquid oil products required worldwide is all related to environmental conservation.

[0007] Therefore, the recent technology for liquid oil such as petroleum
As for the technical trend, especially for the preservation of the urban environment,
SO contained in exhaust gas_X, NO_X,carbon,
Generation of particulate matter such as soot and fine particles (SPM)
Gasoline, which is thought to be the causative substance,
Organic sulfur compounds and aromatic hydrocarbons in liquid oils such as gas oil
It is an urgent task to reduce the content of compounds and other substances.
In particular, SO _X, NO_XEmission of acid gas such as
In liquid oil, which is considered to be
It is urgent to reduce the content of hetero elements from liquid oil
It has become a challenge.

[0008] In the hydrogen reduction desulfurization method, organic sulfur compounds contained in a large amount in fuel oils such as petroleum, particularly light oils, heavy oils or residual oils are difficult to be desulfurized. Since it is difficult to exhibit the activity for a chemically stable compound, a high-accuracy desulfurization technique is desired by further increasing the reaction temperature and hydrogen pressure and improving the activity function of the catalyst.

However, the above-mentioned method for removing sulfur from fuel oil involves treating a fuel oil obtained from petroleum, coal liquefied oil, or the like with an oxidizing agent and maintaining the original chemical structure of an organic sulfur compound. It is desired that the oil be separated from liquid oil while maintaining its original chemical structure, instead of being separated and removed in a state. In the fuel oil refining technology using the above-mentioned solvents, the solvent used for the extraction is mainly composed of nucleophilic organic solvents, and is extracted using industrially inexpensive acetone, methanol, etc. If you do
Since the specific gravity is almost equal to some fuel oils, it may be difficult to separate the hydrocarbon component from the solvent component containing the organic sulfur compound.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the need for a device for raising the temperature and pressure of a liquid oil in order to separate and recover at least the organic sulfur compounds contained in the liquid oil from the liquid oil. Liquid oil which can be easily and inexpensively obtained by using a simple device for separating and recovering organic sulfur compounds from liquid oil without the need for supplying hydrogen to liquid oil or expensive catalysts. It is an object of the present invention to provide a method and an apparatus for separating and recovering at least an organic sulfur compound therein.

The present invention provides a method for separating an organic sulfur compound present in a liquid oil from a liquid oil, comprising adding a solvent having a low solubility to a hydrocarbon compound and a high solubility to the organic sulfur compound to the liquid oil. Transferring the organic sulfur compound contained in the liquid oil into the solvent by utilizing a strong electron donating property of a divalent lone pair of electrons on a sulfur atom, wherein the liquid oil and the organic sulfur compound Separating the mixture comprising the solvent and the liquid oil and the solvent containing the organic sulfur compound by sedimentation and / or centrifugation,
And distilling the separated solvent containing the organic sulfur compound to extract the organic sulfur compound while maintaining the original chemical structure. It relates to a method of separating and collecting.

This method for separating and recovering the organic sulfur compound in the liquid oil is characterized in that, when the difference in specific gravity between the solvent and the liquid oil is small, the specific gravity follows the step of mixing the solvent with the liquid oil. A step of adding a conditioning water to produce a difference in specific gravity sufficient to separate the liquid oil and the solvent, so that a mixture of the liquid oil and the solvent is settled and / or
Alternatively, it can be properly separated by centrifugation. .

[0013] The method for separating and recovering the organic sulfur compound in the liquid oil is characterized in that in the step of separating the mixture into the liquid oil and the solvent containing the organic sulfur compound, Each of the above steps is repeatedly performed until the concentration of the organic sulfur compound becomes equal to or less than a predetermined content.

The solvent is acetone, pinacolin, methyl oxide, 2-butanone, benzophenone, acetylacetone, acetophenone, methanol, ethanol,
Propanol, butanol, acetonitrile, propionitrile, butyronitrile, nitromethane, nitroethane, nitropropane, nitrobenzene, dimethylsulfoxide, pyridine, N'N-dimethylformamide,
N'N-dimethylacetamide, N-methylpyrrolidinone, trimethylphosphoramide, hexamethylphosphoramide,
20% for one or several substances selected from phosphorane, pyrrolidone, pyrrolidinone, imidabridinone
It is a substance selected from a mixture to which water is added in the following concentration range.

Further, the method for separating and recovering the organic sulfur compound in the liquid oil is characterized in that the aromatic hydrocarbon compound contained in the mixture of the solvent and the organic sulfur compound separated from the liquid oil is separated from the mixture. Therefore, the solvent having a high electron-donating property and / or a solvent to which a nucleophile such as OH ⁻ , H ₂ O, etc. is added are mixed to form an electron-donating property of the aromatic hydrocarbon compound and the organic sulfur compound. The aromatic hydrocarbon compound is separated from the organic sulfur compound by utilizing the difference.

Further, the present invention provides a mixing tank provided with a stirrer for mixing a liquid oil containing an organic sulfur compound with a solvent to which water has been added, and centrifuging and / or sedimenting the mixed solution produced in the mixing tank. A separator for separating the liquid oil in a state in which the organic sulfur compound in the liquid oil has been transferred to the solvent from the mixed solution by permeation separation, heating a mixture of the separated solvents to form the solvent and the water A solvent distillation tank for obtaining the organic sulfur compound by evaporating the organic sulfur compound, a recovered organic sulfur compound tank for separating and recovering the solvent and the organic sulfur compound generated in the solvent distillation tank, and a desulfurized liquid oil tank. The present invention relates to an apparatus for separating and recovering an organic sulfur compound in a liquid oil.

Since the present invention is constructed as described above, it does not depend on chemical changes due to high temperature, high pressure, catalyst, etc.
In addition, the organic sulfur compounds in the liquid oil can be separated and removed (recovered) from the liquid oil by mass transfer of the organic sulfur compounds in the liquid oil to the solvent by a method that does not depend on the chemical reaction of reduction and oxidation. The mixture with the solvent is separated by sedimentation and / or centrifugation, and the solvent containing the separated organic sulfur compound is distilled, and the organic sulfur compound can be recovered while maintaining the original chemical structure.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method and an apparatus for separating and recovering organic sulfur compounds in a liquid oil according to the present invention will be described below with reference to the drawings and tables. FIG. 1 is a block diagram for explaining a processing step for achieving a method for separating and recovering an organic sulfur compound in a liquid oil according to the present invention, FIG. 2 is a perspective view showing another embodiment of a separator, and FIG. 2 is a cross-sectional view of the separator,
4 is a cross-sectional view taken along a line II in FIG.

The apparatus for separating and recovering the organic sulfur compound in the liquid oil is produced in a mixing tank 4 and a mixing tank 4 provided with a stirrer 30 for mixing a liquid oil containing the organic sulfur compound with a solvent to which water is added. A centrifugal separator that separates the liquid mixture in a state in which the organic sulfur compounds in the liquid oil have been transferred to the solvent from the mixed liquid by centrifugation and / or sedimentation and permeation separation,
The mixture of the separated solvents is heated to evaporate the solvent and water to obtain an organic sulfur compound. A solvent distillation tank 6 for obtaining an organic sulfur compound, and a recovered organic material for separating and recovering the solvent and the organic sulfur compound generated in the solvent distillation tank 6, respectively. It comprises a sulfur compound tank 7 and a desulfurized liquid oil tank 8. A predetermined amount of water is supplied from an additive tank 9 to the solvent tank 2 containing the solvent. A liquid oil containing an organic sulfur compound is supplied from the liquid oil tank 1 to the mixing tank 4, and a solvent to which water is added is supplied from the solvent tank 2.

This device is constructed as described above. After the water is added from the additive tank 9 to the solvent tank 2 containing the solvent as an additive, the solvent is added to the mixing tank 4 and the mixing tank 4 , A liquid oil containing an organic sulfur compound is charged from the liquid oil tank 1. In the mixing tank 4, the liquid oil and the solvent are stirred and mixed by the stirrer 30 to form a mixed liquid, and the organic sulfur compound in the liquid oil is transferred to the solvent. Next, the liquid mixture is separated into a liquid oil and a solvent containing an organic sulfur compound by the centrifugal separator 5. In this case, if the difference in specific gravity between the liquid oil and the solvent containing the organic sulfur compound is not sufficient, water is mixed from the specific gravity adjusting water tank 3 into the mixed solution in the mixing tank 4 and stirred and mixed by the stirrer 30. Make a mixture. The liquid mixture is separated by a centrifuge 5 into a liquid oil and a solvent containing an organic sulfur compound. When the additive to be added to the additive tank 9 is water, the additive tank 9 and the specific gravity adjusting water tank 3 can be configured in the same tank. The desulfurized liquid oil separated by the centrifuge 5 is transferred to the desulfurized liquid oil tank 8, and the solvent containing the organic sulfur compound is sent to the distillation tank 6. Next, the solvent containing the organic sulfur compound is distilled in the distillation tank 6, the distilled solvent is returned to the solvent tank 2, the additives are returned to the additive tank 9, and the specific gravity adjusting water is returned to the specific gravity adjusting water tank 3. Then, the organic sulfur compound recovered as the distillation residue is recovered in the recovered organic sulfur compound tank 7. The solvent volatilized by stirring by the stirrer 30 is collected from the upper part of the mixing tank 4 into the solvent tank 2 through the pipe 24.

In FIG. 1, the centrifugal separator 5 is shown as a separator. However, if the specific gravities of the various liquids in the mixed liquid are slightly different, the centrifugal separator 5 cannot separate them. The separator 10 according to the difference in specific gravity shown in FIGS.

When the mixture is put into the separator, the mixture is fed in a state where the liquid in the mixture is separated into layers without flowing in the mixture in a turbulent state. It can be separated into layers by a slight difference in specific gravity. The separator 10 has an inner cylinder 14 inside an outer cylinder 25.
Are arranged in a separated state, an inner separation chamber 20 is formed in the inner cylinder 14, and an outer separation chamber 21 is formed between the inner peripheral surface of the outer cylinder 25 and the outer peripheral surface of the inner cylinder 14. At the center between the outer cylinder and the inner cylinder, a mixed liquid supply pipe 26 whose mixed liquid inlet 11 opens into the inner separation chamber 20 penetrates. A light liquid outlet 12 is formed in an upper part of the outer cylinder 25, and a heavy liquid outlet 13 is formed in a lower part of the outer cylinder 25. The inner cylinder 14 is formed with a vertically extending guide portion 19 protruding in an edge shape on a wall surface facing the mixed liquid inlet 11.

Above the inner cylinder 14, an upper partition 15 is installed with a light liquid passage 27 formed on the outer periphery thereof.
A lower partition 16 is provided below the inner cylinder 14 with a heavy liquid passage 28 formed on the outer periphery thereof. The upper partition wall 15 and the lower partition wall 16 are respectively supported by the outer cylinder 25 by the support rod 17, and are also supported by the inner cylinder 14 by the support rod 18. A light liquid chamber 22 is formed above the upper partition 15, and a heavy liquid chamber 23 is formed below the lower partition 16. Light liquid outlet 12
Is provided in the light liquid chamber 22. The heavy liquid outlet 13 is
The heavy liquid chamber 23 is provided.

Since the separator 10 is constructed as described above, the mixed liquid sent from the mixed liquid supply pipe 26 to the inner separation chamber 20 through the mixed liquid inlet 11 does not become a turbulent flow, The light liquid is guided upward in the inner separation chamber 20, and the heavy liquid is guided downward and separated in the inner separation chamber 20. The light liquid guided upward through the inner separation chamber 20 is
The upper partition 1 is passed through the light liquid passage 27 along the upper partition 15.
5 enters the light liquid chamber 22 while bypassing the light liquid 5, and is taken out of the light liquid chamber 22 through the light liquid outlet 12. Also, the inner separation chamber 2
The heavy liquid guided downwardly along the bottom wall 16 passes through the heavy liquid passage 28 along the lower bulkhead 16 and bypasses the lower bulkhead 16 while passing through the heavy bulkhead 2.
3 and is taken out of the heavy liquid chamber 23 through the heavy liquid outlet 13.

When the aromatic hydrocarbon compound contained in the mixture of the solvent separated from the liquid oil and the organic sulfur compound is separated, the separator 10 adds the solvent to the mixture and converts the organic sulfur compound into the solvent. In the case of the transfer, the aromatic hydrocarbon compound moves downward as a heavy liquid and is taken out from the heavy liquid outlet 13, and the mixed liquid of the organic sulfur compound and the solvent moves upward as a light liquid and lightens. The aromatic hydrocarbon compound is taken out from the liquid outlet 12 and can be separated from the organic sulfur compound.

Next, specific examples of the method for separating and recovering organic sulfur compounds in liquid oil according to the present invention will be described.

Example 1 50 ml of commercially available light oil (sulfur content 240 ppm) was put into the reaction vessel of the mixing tank 4 from the liquid oil tank 1, 50 ml of acetone and 0.5 ml of water were added from the solvent tank 2, and a stirrer 30 was added. Was operated and the mixture was stirred at 400 rpm for 60 seconds to obtain a mixture. The obtained mixture was transferred to the centrifugal separator 5, and the centrifugal separator 5 was operated to separate a gas oil fraction and an acetone fraction using a separating funnel. After the gas oil fraction and the acetone fraction were allowed to stand overnight, the gas oil fraction and the acetone fraction were separated again. The separated light oil fraction was recovered in the desulfurized liquid oil tank 8, and the separated acetone fraction was transferred to the distillation tank 6. The acetone fraction in the distillation tank 6 was distilled, acetone was returned to the solvent tank 2, and the organic sulfur compound was recovered in the recovery organic sulfur compound tank 7. Further, the concentration of the organic sulfur compound in the purified light oil fraction from which the organic sulfur compound transferred to the desulfurization liquid oil tank 8 was removed was measured. Diesel oil was subjected to the above treatment steps under the conditions of 10 ° C. and 25 ° C., and the results were compared. Table 1 shows the results.

[Table 1]

Example 2 50 ml of commercially available light oil (sulfur content 240 ppm) was put into the reaction vessel of the mixing tank 4 from the liquid oil tank 1, 50 ml of acetone and 0.5 ml of water were added from the solvent tank 2, and a stirrer 30 was added. With stirring at 400 rpm for 60 seconds. Further, 10 ml of water was added to the mixing tank 4 from the water tank 3 for specific gravity adjustment, and the mixture was stirred at 400 rpm for 60 seconds by the stirrer 30 to transfer the organic sulfur compound in the light oil to the solvent of acetone to obtain a mixture. The obtained mixture is transferred to the centrifugal separator 5, and the centrifugal separator 5 is operated to separate the mixture transferred to the centrifugal separator 5, and the light oil fraction and the acetone fraction are separated using a separating funnel. separated. The gas oil fraction and the acetone fraction are allowed to stand for 24 hours a day, the gas oil fraction and the acetone fraction are re-separated from each other, the separated gas oil fraction is collected in the desulfurized liquid oil tank 8, and the separated acetone fraction is distilled. Transferred to tank 6.
The concentration of the organic sulfur compound in the gas oil fraction collected in the desulfurized liquid oil tank 8 was measured. Light oil is obtained by each of the above processing steps.
The test was performed under the conditions of 10 ° C and 25 ° C, and the results were compared. Table 2 shows the results.

[Table 2]

Example 3 50 ml of commercially available light oil (sulfur content 240 ppm) was put into the reaction vessel of the mixing tank 4 from the liquid oil tank 1, 50 ml of acetone and 10.5 ml of water were added from the solvent tank 2, and a stirrer 30 was added. Was operated and the mixture was stirred at 400 rpm for 60 seconds to obtain a mixture in which the organic sulfur compound in the light oil was transferred to the solvent. The obtained mixture was transferred to a centrifugal separator 5, and in order to separate the mixture, the centrifugal separator 5 was operated, and separated into a light oil fraction and an acetone fraction using a separating funnel. The gas oil fraction and the acetone fraction were allowed to stand all day and night, the gas oil fraction and the acetone fraction were re-separated, respectively, the gas oil fraction was collected in the desulfurized liquid oil tank 8, and the acetone fraction was transferred to the distillation tank 6. did. The concentration of the organic sulfur compound in the gas oil fraction in the desulfurized liquid oil tank 8 was measured. The light oil is treated at 10 ° C and 2
The test was performed under the condition of 5 ° C., and the results were compared.
Table 3 shows the results.

[Table 3]

[0030]

The method and apparatus for recovering organic sulfur compounds from liquid oil according to the present invention are constructed as described above, so that organic sulfur compounds contained in liquid oil such as light oil can be easily converted. With the use of simple equipment, it is possible to recover with high efficiency and low cost while maintaining its chemical structure. The recovered organic sulfur compounds can be used as useful resources in the fields of manufacturing medicine, agricultural chemicals, heat-resistant resins, and the like. In addition, this method of recovering organic sulfur compounds from liquid oil can be applied as a desulfurization method for light and heavy oils. It can be applied to desulfurization methods that do not require reaction conditions, consume little energy, generate no coke, and do not require hydrogen reduction, and this economic effect is remarkable.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining a processing step for achieving a method for separating and recovering an organic sulfur compound in a liquid oil by adding water according to the present invention.

FIG. 2 is a perspective view showing another embodiment of the separator.

FIG. 3 is a sectional view of the separator of FIG. 2;

FIG. 4 is a cross-sectional view taken along the line II of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid oil tank 2 Solvent tank 3 Water tank 4 Mixing tank 5 Centrifugal separator 6 Distillation tank 7 Recovered organic sulfur compound tank 8 Desulfurized liquid oil tank 9 Additive tank 10 Separator 11 Mixed liquid inlet 12 Light liquid outlet 13 Heavy liquid Outlet 14 Inner cylinder 15 Upper partition 16 Lower partition 17, 18 Support rod 19 Guide part 20 Inner separation chamber 21 Outer separation chamber 22 Light liquid chamber 23 Heavy liquid chamber 24 Pipe 25 Outer cylinder 26 Mixed liquid supply pipe 27 Light liquid passage 28 Heavy liquid passage 30 Stirrer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01D 17/028 B01D 17/028 Z 17/038 17/038 C10G 21/16 C10G 21/16 21/20 21 / 20 21/22 21/22 21/24 21/24 31/10 31/10 F term (reference) 4D056 AB18 AC06 AC08 AC11 AC15 AC18 AC22 BA01 BA05 BA09 CA06 CA15 CA20 CA27 CA37 4H029 DA01 DA05

Claims (6)

[Claims] 1. A method for separating an organic sulfur compound present in a liquid oil from a liquid oil, comprising: adding a solvent having a low solubility to a hydrocarbon compound and a high solubility to the organic sulfur compound to the liquid oil; Transferring the organic sulfur compound contained in the liquid oil into the solvent by utilizing a strong electron donating property of a divalent lone electron pair on a sulfur atom, containing the liquid oil and the organic sulfur compound The mixture comprising the solvent and
Or a step of separating the liquid oil and the solvent containing the organic sulfur compound by centrifugation, and distilling the separated solvent containing the organic sulfur compound to obtain the original chemical structure of the organic sulfur compound. A method of separating and recovering organic sulfur compounds in a liquid oil, comprising a step of extracting while maintaining the same. 2. When the difference in specific gravity between the solvent and the liquid oil is small, the liquid oil and the solvent are mixed by adding water for specific gravity adjustment after the step of mixing the solvent with the liquid oil. 2. The method for separating and recovering an organic sulfur compound in a liquid oil according to claim 1, comprising a step of causing a difference in specific gravity sufficient for the separation of the oil. 3. In the step of separating the mixture into the liquid oil and the solvent containing the organic sulfur compound, the concentration of the organic sulfur compound in the obtained liquid oil is a predetermined value. The method for separating and recovering an organic sulfur compound in a liquid oil according to claim 1, wherein each of the steps is repeatedly performed until the content becomes equal to or less than the content. 4. The solvent is acetone, pinacolin, methyl oxide, 2-butanone, benzophenone, acetylacetone, acetophenone, methanol, ethanol, propanol, butanol, acetonitrile, propionitrile, butyronitrile, nitromethane, nitroethane, nitropropane, nitrobenzene. , Dimethylsulfoxide, pyridine, N'N-dimethylformamide, N'N-dimethylacetamide, N-methylpyrrolidinone, trimethylphosphoramide, hexamethylphosphoramide, phosphorane, pyrrolidone, pyrrolidinone, imidabridinone 2 for
The method for separating and recovering an organic sulfur compound in a liquid oil according to claim 1, wherein the substance is selected from a mixture to which water is added in a concentration range of 0% or less. 5. The solvent and / or OH having a high electron donating property for separating an aromatic hydrocarbon compound contained in the mixture of the solvent and the organic sulfur compound separated from the liquid oil from the mixture. ^And a solvent to which a nucleophile such as-, H ₂ O, or the like is added, and the aromatic hydrocarbon compound is converted to the organic sulfur compound by utilizing a difference in electron donating property between the aromatic hydrocarbon compound and the organic sulfur compound. The method for separating and recovering an organic sulfur compound in a liquid oil according to claim 1, wherein the organic sulfur compound is separated from the compound. 6. A mixing tank provided with a stirrer for mixing a liquid oil containing an organic sulfur compound with a solvent to which water has been added, and centrifuging and / or sedimenting the mixed liquid produced in the mixing tank.
A separator that separates the liquid oil in a state where the organic sulfur compound in the liquid oil has migrated to the solvent from the mixed solution by permeation separation, heating a mixture of the separated solvents to form the solvent and the water; A solvent distillation tank for evaporating the solvent to obtain the organic sulfur compound, and a recovery organic sulfur compound tank and a desulfurization liquid oil tank for separating and recovering the solvent and the organic sulfur compound generated in the solvent distillation tank, respectively. For separating and recovering organic sulfur compounds in liquid oil.