A process and apparatus for desulfurization of crude hydrocarbon composition such as diesel or kerosene

Abstract

A process for desulfurization of a crude hydrocarbon composition, such as diesel or kerosene, where the process comprises the steps of a) providing an oxidized crude hydrocarbon composition containing at least one oxidized sulfur-containing compound, b) liquid-liquid extraction of the oxidized crude hydrocarbon composition provided in step a) with an extractant, c) washing the raffinate obtained in step b) with a detergent in order to remove the remaining extractant from the raffinate, thereby obtaining a desulfurized hydrocarbon composition and a mixture of detergent and extractant, and c) removing the desulfurized hydrocarbon composition from the mixture of detergent and extractant, d) subjecting the extract obtained in step b) to at least one purification step to obtain a purified extractant and a waste composition wherein the purified extractant is at least partially recycled to step b), and e) subjecting the mixture of detergent and extractant obtained in step c) to multi-stage evaporation to separate extractant from detergent, the multi-stage evaporation comprises at least two subsequent evaporation steps, and wherein the first evaporation step is carried out at a higher pressure than at least one of the subsequent evaporation steps, whereby a purified detergent is obtained, in which the purified detergent is at least partially recycled to step c), and wherein the multi-stage evaporation comprises at least two subsequent evaporation steps.

Description

[0001] The present invention relates to a method and an apparatus for desulfurizing a crude hydrocarbon composition (such as diesel or kerosene).

[0002] Removing non-hydrocarbon components, and in particular sulfur-containing compounds, from a hydrocarbon composition is important because such non-hydrocarbon components, and in particular sulfur-containing compounds, can severely affect the downstream applications of the hydrocarbon composition. Thus, a prominent example is hydrocarbon fuels such as diesel, kerosene, gasoline, fuel oil, etc., which are burned in internal combustion engines, turbines, fuel burners of fuel heaters, etc. During combustion, sulfur-containing compounds are converted into harmful and toxic compounds, severely causing environmental pollution. In addition, at least some of these compounds are corrosive and will therefore damage internal combustion engines, turbines, fuel heaters, etc. In addition, sulfur is a catalyst poison and will severely damage catalyst systems, such as the catalyst systems of automobiles. For these reasons and in order to meet environmental regulations, it is necessary to remove sulfur-containing compounds (such as mercaptans, sulfides, disulfides, thiophenes, etc.) from a crude hydrocarbon composition (such as diesel, petroleum or kerosene), and then the desulfurized hydrocarbon composition can be used as a combustion fuel.

[0003] A variety of methods for desulfurizing crude hydrocarbon compositions are known. Most of these methods first oxidize the sulfur-containing compounds in the hydrocarbon composition and then separate the oxidized sulfur-containing compounds from the hydrocarbon composition by separation techniques. For this purpose, examples of commonly used separation techniques are those based on liquid-liquid extraction, adsorption, precipitation, and / or chemical decomposition, and most of these separation techniques employ at least one liquid-liquid extraction step. However, the known methods for desulfurizing crude hydrocarbon compositions have one or more of the following disadvantages, namely, they require a relatively large amount of extractant or solvent, are quite energy-consuming, and can only achieve an insufficient degree of desulfurization.

[0004] In view of this, an object of the present invention is to provide a method and an apparatus for desulfurizing a crude hydrocarbon composition containing at least one sulfur-containing compound on an industrial scale, wherein the method combines particularly low energy consumption and particularly low extractant consumption, but still results in a purified hydrocarbon composition having a particularly low sulfur content of as low as 10 ppm or even lower.

[0005] According to the present invention, this object is achieved by providing a method for desulfurizing a crude hydrocarbon composition (such as diesel or kerosene), wherein the method comprises the following steps:

[0006] a) providing an oxidized crude hydrocarbon composition containing at least one oxidized sulfur-containing compound,

[0007] b) subjecting the oxidized crude hydrocarbon composition provided in step a) to liquid-liquid extraction with an extractant to obtain an extract rich in at least one oxidized sulfur-containing compound and a raffinate poor in at least one oxidized sulfur-containing compound,

[0008] c) Wash the raffinate obtained in step b) with a detergent to remove the remaining extractant from the raffinate, thereby obtaining a desulfurized hydrocarbon composition and a mixture of the detergent and the extractant,

[0009] d) Perform at least one purification step on the extract obtained in step b) to obtain a purified extractant and a waste composition, wherein the purified extractant is at least partially recycled to step b), and

[0010] e) Subject the mixture of the detergent and the extractant obtained in step c) to multi-stage evaporation to obtain a purified detergent and a purified extractant, wherein the purified detergent is at least partially recycled to step c), and wherein the multi-stage evaporation comprises at least two successive evaporation steps, wherein the first evaporation step is carried out at a higher pressure than at least one of the subsequent evaporation steps.

[0011] This solution is based on the following findings. By combining i) liquid-liquid extraction of an oxidized crude hydrocarbon composition with an extractant; ii) washing the raffinate obtained in the liquid-liquid extraction with a detergent to remove the extractant from the raffinate; and iii) recovering the extractant from the extract of the liquid-liquid extraction, thereby allowing the extractant to be recycled to the liquid-liquid extraction; and in particular iv) recovering the detergent from the mixture of the detergent and the extractant obtained in the raffinate washing step by multi-stage evaporation, wherein the first evaporation step of the multi-stage evaporation is carried out at a pressure higher than the pressure of at least one of the subsequent evaporation steps, a particularly high degree of desulfurization is obtained with particularly low energy consumption and particularly low extractant consumption. One of the reasons is that the multi-stage evaporation can effectively separate the extractant from the detergent in the mixture of the detergent and the extractant (obtained during the raffinate washing process), so that a very pure detergent and a very pure extractant can be obtained in the method according to the invention, which enables most of the applied detergent to be recovered and recycled to the raffinate washing step c), and most of the applied extractant to be recovered and recycled to the liquid-liquid extraction step b). Thereby, the amounts of the required fresh detergent and the required fresh extractant are minimized. In addition, in the multi-stage evaporation, the first evaporation step is carried out at a pressure higher than the pressure of at least one of the subsequent evaporation steps, which enables the vapor generated in the first evaporation step to be used as the heat source for at least one of the subsequent evaporation steps, thereby minimizing the energy requirement for evaporation. In summary, the method according to the invention allows the effective desulfurization of an oxidized crude hydrocarbon composition containing at least one (oxidized) sulfur-containing compound on an industrial scale, wherein the method is characterized by particularly low energy consumption and particularly low extractant consumption, but a purified hydrocarbon composition with a sulfur content as low as 10 ppm or even lower can be obtained.

[0012] According to the present invention, in step a), an oxidized crude hydrocarbon composition containing at least one oxidized sulfur-containing compound is provided. The oxidized crude hydrocarbon composition containing at least one oxidized sulfur-containing compound can be obtained by any treatment for oxidizing the sulfur-containing compounds in the hydrocarbon composition. Preferably, the oxidized crude hydrocarbon composition containing at least one oxidized sulfur-containing compound provided in step a) is obtained by reacting a crude hydrocarbon composition containing at least one sulfur-containing compound with an oxidizing agent.

[0013] The present invention has no particular limitation on the type of the crude hydrocarbon composition to be desulfurized. It is particularly applicable to desulfurize a crude hydrocarbon composition selected from diesel, kerosene, gasoline, naphtha, vacuum gas oil, light cycle oil, heavy cycle oil, marine gas oil, marine diesel oil, marine fuel oil, residue, lubricating oil, and any combination of two or more of the above compositions. Therefore, preferably, the oxidized crude hydrocarbon composition provided in step a) is preferably an oxidation product of a composition selected from diesel, kerosene, gasoline, naphtha, vacuum gas oil, light cycle oil, heavy cycle oil, marine gas oil, marine diesel oil, marine fuel oil, residue, lubricating oil, and any combination of two or more of the above compositions.

[0014] The present invention also has no particular limitation on the content of the sulfur-containing compound. For example, good results are achieved if the crude hydrocarbon composition contains 10 to 50,000 ppm, and preferably 10 to 10,000 ppm, of one or more sulfur-containing compounds. Therefore, the oxidized crude hydrocarbon composition provided in step a) preferably contains 10 to 50,000 ppm, and preferably 10 to 10,000 ppm, of one or more oxidized sulfur-containing compounds.

[0015] A particular advantage of the method according to the present invention is that it is suitable for removing almost all sulfur-containing compounds from the crude hydrocarbon composition, that is, all sulfur-containing compounds - at least when using a suitable catalyst and appropriate reaction conditions - are oxidizable. In particular, the method according to the present invention is applicable to remove mercaptans, sulfides, disulfides, thiophenes, benzothiophenes, dibenzothiophenes (such as 4,6-dimethyldibenzothiophene, tetrahydrodibenzothiophene, tetrahydrodibenzonaphthothiophene, and octahydrodinaphthothiophene), and any combination of two or more of the above sulfur-containing compounds. Therefore, preferably, at least one sulfur-containing compound contained in the crude hydrocarbon composition is selected from mercaptans, sulfides, disulfides, thiophenes, benzothiophenes, dibenzothiophenes (such as 4,6-dimethyldibenzothiophene, tetrahydrodibenzothiophene, tetrahydrodibenzonaphthothiophene, and octahydrodinaphthothiophene), and any combination of two or more of the above compounds.

[0016] To react with a crude hydrocarbon composition containing at least one sulfur-containing compound to provide the oxidized crude hydrocarbon composition provided in step a), any oxidizing agent capable of oxidizing one or more sulfur-containing compounds contained in the crude hydrocarbon composition can be used. Particularly good results are obtained when the oxidizing agent used in step a) is selected from hydrogen peroxide, metal peroxides, metal permanganates, metal hypochlorites, metal perchlorates, metal perborates, fluorine, chlorine, and any combination of two or more of the above compounds. For example, the oxidizing agent oxidizes one or more sulfur-containing compounds to sulfones, such as butyl methyl sulfone, methyl phenyl sulfone, thiophene sulfone, benzothiophene sulfone, dibenzothiophene sulfone, or 2-methylbenzothiophene sulfone.

[0017] There is no particular limitation on the chemical properties of the extractant according to the method of the present invention, as long as the extractant can extract the oxidized sulfur compounds from the hydrocarbons of the hydrocarbon composition, such as especially sulfones. Particularly good results are obtained when using aprotic and / or polar extractants. The extractants particularly suitable for use in step b) are selected from methanol, acetonitrile, N-methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, furfural, sulfolane, and any combination of two or more of the above compounds. Methanol is an example of a protic polar extractant, while dimethylformamide, acetonitrile, N-methyl-2-pyrrolidone, dimethyl sulfoxide, and furfural are examples of aprotic polar extractants. Particularly preferably, the extractant is an aprotic extractant, and most preferably the extractant is selected from methanol, acetonitrile, N-methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, furfural, sulfolane, and any combination of two or more of the above compounds. According to the present invention, an aprotic compound means any compound that neither accepts nor donates hydrogen ions, while a protic compound accepts or donates hydrogen ions. In addition, according to the present invention, a polar compound means any compound having an electric dipole moment of at least 1.5 Debye, and preferably at least 3.2 Debye, where 1 Debye corresponds to 3.33564·10 - 30 C·m.

[0018] Preferably, the weight ratio of the amount of the extractant to the amount of the oxidized crude hydrocarbon composition in step b) is from 0.01 to 3, and more preferably from 0.1 to 1.

[0019] According to a particularly preferred embodiment of the present invention, the liquid-liquid extraction in step b) is carried out in a stirred extraction column. Particularly good results are obtained when the liquid-liquid extraction in step b) is carried out in a stirred countercurrent extraction column. Carrying out the liquid-liquid extraction in step b) in a stirred extraction column can improve the efficiency of the liquid-liquid extraction, thereby minimizing the amount of extractant required for the liquid-liquid extraction.

[0020] The stirred extraction column comprises at least one, and preferably a plurality, for example from 2 to 80, and more preferably from 5 to 40, stirring internals arranged within the extraction column. For example, each stirring internal comprises one or more rotating shafts, each rotating shaft being connected to one or more stirrers, which stirrers are preferably selected from discs, blades, paddles, turbine impellers, fins and any combination of two or more of the above-mentioned stirrers. Furthermore, the stirred extraction column preferably comprises an extractant inlet line, an inlet line for the oxidized crude hydrocarbon composition, an extract outlet line and a raffinate outlet line. Preferably, the extractant inlet line and the inlet line for the oxidized crude hydrocarbon composition are arranged at opposite ends of the extraction column. Similarly, the extract outlet line and the raffinate outlet line are preferably arranged at opposite ends of the extraction column, wherein the extract outlet line and the inlet line for the oxidized crude hydrocarbon composition are arranged at the same end of the extraction column, and wherein the raffinate outlet line and the extractant inlet line are arranged at the same end of the extraction column.

[0021] Good results are particularly obtained when the stirred extraction column comprises two or more compartments separated from one another by static partitions, wherein at least some and preferably all of the compartments comprise a rotating shaft which comprises one or more stirrers, which stirrers are preferably selected from: discs, blades, paddles, turbine impellers, fins and any combination of two or more of the above-mentioned stirrers.

[0022] For example, an extraction column for carrying out stirred liquid-liquid extraction can be embodied as a Kühni column or the like.

[0023] A further development of the inventive concept provides that the extraction in step b) is carried out in the form of a multi-stage extraction. Preferably, the multi-stage extraction comprises from 6 to 12 stages. The "stage" herein refers to a theoretical stage, which is a thermodynamic model of staged mass transfer, meaning that the streams leaving the theoretical stage are in thermodynamic equilibrium. Any of these theoretical stages preferably comprises a number of stirred chambers of the column.

[0024] Furthermore, in order to achieve particularly high efficiency in the liquid-liquid extraction carried out in step b), and thus to minimize the energy requirement and the amount of extractant required, it is particularly preferred that, if a stirred extraction column with one or more rotating shafts is used in step b), the rotational speed of the rotating shaft in step b) is adjusted to from 5 to 1,000 rpm, and more preferably to from 5 to 50 rpm.

[0025] In the liquid-liquid extraction process carried out in step b), a two-phase system is treated, where one phase is the extractant and the other phase is the oxidized crude hydrocarbon composition to be extracted. Usually, the extractant phase will form the continuous phase, and the droplets of the oxidized crude hydrocarbon composition are dispersed therein. However, the oxidized crude hydrocarbon composition may also form the continuous phase, with the droplets of the extractant phase dispersed therein. To make the liquid-liquid extraction carried out in step b) particularly efficient, thus minimizing the energy requirements and the amount of extractant required, it is particularly preferred that when using a stirred extraction column in step b), the stirred extraction column is operated such that the droplet size dispersed in the continuous phase is from 0.5 to 10 mm, and more preferably from 1 to 3 mm.

[0026] In a further development of the inventive concept, it is proposed to use an extractant in step b) such that the difference in density between the extractant and the oxidized crude hydrocarbon composition is from 15 to 400 kg / m 3 . This also contributes to achieving particularly high efficiency in the liquid-liquid extraction carried out in step b), thus minimizing the energy requirements and the amount of extractant required.

[0027] When using an extractant in step b) such that the interfacial tension between the extractant and the oxidized crude hydrocarbon composition is from 0.0005 to 0.07 N / m (this interfacial tension is measured by the drop volume method using a drop volume tensiometer - DVT50 from Scientific), particularly good results are obtained in the following aspects: the liquid-liquid extraction carried out in step b) is efficient, and the energy requirements and the amount of extractant required are minimized.

[0028] According to another particularly preferred embodiment of the invention, the above embodiments are combined with each other. Preferably, at least two of the following five criteria are met in step b), more preferably at least three, even more preferably at least four, and most preferably all are met.

[0029] i) The liquid-liquid extraction is carried out in a stirred extraction column, which comprises one or more rotating shafts, each rotating shaft comprising one or more stirrers, which stirrers are preferably selected from discs, blades, paddles, turbine impellers, fins, and any combination of two or more of the above stirrers, wherein the rotational speed of one or more rotating shafts is adjusted to 5 to 1,000 rpm, and more preferably to 5 to 50 rpm,

[0030] ii) In the liquid-liquid extraction process carried out in step b), a two-phase system is treated, where the extractant forms the continuous phase, where the droplets of the oxidized crude hydrocarbon composition are dispersed in this continuous phase, where the stirred extraction column is operated such that the droplet size dispersed in the continuous phase is from 0.5 to 10 mm, and more preferably from 1 to 3 mm,

[0031] iii) In step b), an extractant is used such that the difference in density between the extractant and the oxidized crude hydrocarbon composition is 15 to 400 kg / m 3 ,

[0032] iv) In step b), an extractant is used such that the interfacial tension between the extractant and the oxidized crude hydrocarbon composition is from 0.0005 to 0.07, and / or

[0033] v) In step b), an extractant having an electric dipole moment of at least 1.5 Debye, preferably at least 3.2 Debye, and more preferably from 3.2 to 4.2 Debye is used.

[0034] Preferably, the raffinate obtained in step b) has a sulfur compound content of at most 25 ppm, preferably at most 20 ppm, more preferably at most 15 ppm, and most preferably at most 10 ppm. The content of the extractant in the raffinate obtained in step b) can be from 5,000 to 100,000 ppm.

[0035] If the extractant is a hydrocarbon or a hydrocarbon-containing mixture, the extract obtained in step b) can have a content of one or more oxidized sulfur compounds of from 10 to 120,000 ppm and a hydrocarbon content of at most 100,000 ppm derived from the crude hydrocarbon composition and different from the extractant.

[0036] Any compound having a higher solubility in the extractant than in the hydrocarbon can be used as the detergent in step c). Particularly good results are obtained when the detergent used in step c) is an aqueous solution containing at least 50% by weight of water, preferably at least 80% by weight of water, more preferably at least 95% by weight of water, and most preferably 100% by weight of water.

[0037] Preferably, step c) is carried out in a stirred column. Particularly good results are obtained when step c) is carried out in a countercurrent stirred column. All the preferred embodiments of the liquid-liquid extraction column used in step b) are also preferred for the column used to carry out the washing step c).

[0038] According to another specific embodiment of the present invention, steps b) and c) are carried out in two different apparatuses, for example in an extraction column and a washing column.

[0039] However, steps b) and c) can also be carried out in one device. For example, the liquid-liquid extraction unit b) and the washing unit c) can both be included in a column, which includes a first type of compartment separated from each other by static partitions, where each of these compartments includes a rotating shaft, which includes one or more agitators, which are preferably selected from discs, blades, paddles, turbine impellers, fins, and any combination of two or more of the above-mentioned agitators; and the column includes a second type of compartment separated from each other by static partitions, where each compartment includes a rotating shaft, which includes one or more agitators, which are preferably selected from discs, blades, paddles, turbine impellers, fins, and any combination of two or more of the above-mentioned agitators; where the geometry and / or dimensions of one or more compartments and / or agitators of the first type of compartment can be the same as or different from those of the second type of compartment.

[0040] As mentioned above, a particular advantage of the method according to the invention is that it can effectively remove sulfur-containing compounds from the crude hydrocarbon composition. Particularly preferably, the sulfur-containing compound content of the desulfurized hydrocarbon composition obtained in step c) is at most 20 ppm, and more preferably at most 10 ppm, the detergent content is at most 20,000 ppm, and more preferably at most 10,000 ppm, and the extractant content is at most 25,000 ppm, and more preferably at most 11,000 ppm.

[0041] According to the invention, in step d), at least one purification step is carried out on the extract obtained in step b) to obtain a purified extractant and a waste composition, where the purified extractant is at least partially recycled to step b). Any purification technique capable of removing impurities (such as one or more oxidized sulfur compounds extracted) from the extract can be used. Thus, a suitable example is to carry out at least one distillation step on the extract obtained in step b) in step d). Particularly good results are obtained when at least two successive distillation steps are carried out on the extract obtained in step b) in step d), where the overhead distillate composition obtained in the first distillation step is introduced into the subsequent distillation step, where the purified extractant is recovered as the bottoms composition from the subsequent distillation step and at least partially recycled as the extractant to step b).

[0042] Alternatively, in step d), a multi-stage evaporation comprising at least two subsequent evaporation steps can be used as at least one purification step. This enables a reduction in energy consumption and thus a reduction in operating costs. The multi-stage evaporation used in step d) is preferably carried out in the same way as the multi-stage evaporation used in step e) described above and below. In addition to the multi-stage evaporation, at least one purification step of this embodiment can also include one or more (e.g., two) distillation steps. For example, the liquid phase obtained in the multi-stage evaporation can be distilled in a first distillation step to remove heavy components from the composition, and then the overhead distillate composition obtained in the first distillation step can be fed together with the gas phase obtained in the multi-stage evaporation to a second distillation step to separate the remaining detergent from the extractant.

[0043] According to the invention, in step e), the mixture of the detergent and the extractant obtained in step c) is subjected to multi-stage evaporation to separate the extractant from the detergent, thereby obtaining a purified detergent, wherein the multi-stage evaporation comprises at least two subsequent evaporation steps, and the first evaporation step is carried out at a pressure higher than the pressure of at least one subsequent evaporation step. Particularly good results are obtained when the pressure difference between the pressure at which the first evaporation step is carried out and the pressure at which the second evaporation step is carried out is from 30 to 150 kPa, and more preferably from 45 to 55 kPa.

[0044] Preferably, the multi-stage evaporation carried out in step e) includes a first evaporation step and at least a subsequent second evaporation step, wherein the mixture of detergent and extractant obtained in step c) is introduced into the first evaporation step and separated therein into a first gas phase and a first liquid phase. The first liquid phase is introduced into the second evaporation step and separated therein into a second gas phase and a second liquid phase, wherein the first gas phase is used as a heat source in the second evaporation step. More specifically, the evaporator in which the second evaporation step is carried out includes a heat exchanger, and the first gas phase is fed to the heat exchanger as a heat source to heat the first liquid phase introduced into the second evaporator. In addition, the evaporator in which the first evaporation step is carried out preferably includes a heat exchanger, and an external heating medium is fed to the heat exchanger and the heat exchanger is operated by the external heating medium. Alternatively, the heat can be provided by the gas phase of the last column, which is recompressed by mechanical vapor recompression (MVR). The first evaporation step is preferably carried out at an absolute pressure of 200 to 400 kPa, and more preferably at an absolute pressure of 250 to 300 kPa, while the second evaporation step is preferably carried out at an absolute pressure of 100 to 250 kPa, and more preferably at an absolute pressure of 160 to 230 kPa, for example, at an absolute pressure of about 170 kPa. Similarly, the pressure difference between the pressure at which the first evaporation step is carried out and the pressure at which the second evaporation step is carried out is preferably 30 to 150 kPa, and more preferably 45 to 55 kPa. During the first evaporation step, the temperature of the liquid is preferably 130 to 140 °C, while during the second evaporation step, the temperature of the liquid is preferably 110 to 130 °C. If the second evaporation step is the last evaporation step of the multi-stage evaporation carried out in step e), at least a part of the second liquid phase will be recycled as a detergent to step c) or used as a heat source in the first evaporation step.

[0045] In addition, preferably between the first and second evaporation steps, the first gas phase is compressed and then used as a heat source for the second evaporation step, i.e., before it is fed to the heat exchanger of the evaporator in which the second evaporation step is carried out. For this purpose, any type of compression can be used, and preferably mechanical vapor recompression (MVR) is carried out.

[0046] In a further development of the inventive concept, it is proposed that the multistage evaporation carried out in step e) further comprises at least a subsequent third evaporation step, in which the second liquid phase is introduced into the third evaporation step and separated therein into a third gas phase and a third liquid phase, wherein the second gas phase serves as a heat source in the third evaporation step. More specifically, the evaporator in which the third evaporation step is carried out comprises a heat exchanger, to which the second gas phase is fed as a heat source to heat the second liquid phase introduced into the third evaporator. Preferably, the third evaporation step is carried out at an absolute pressure of 50 to 150 kPa, and more preferably at an absolute pressure of 70 to 130 kPa, for example at an absolute pressure of about 80 kPa. Particularly good results are obtained when the pressure difference between the pressure at which the second evaporation step is carried out and the pressure at which the third evaporation step is carried out is 50 to 150 kPa, and preferably 90 to 100 kPa. The temperature of the liquid during the third evaporation step is preferably 90 to 130 °C. If the third evaporation step is the last evaporation step of the multistage evaporation carried out in step e), at least a part of the third liquid phase is recycled as a detergent to step c) or serves as a heat source in the first evaporation step.

[0047] Furthermore, in the present embodiment, it is preferred that between the second evaporation step and the third evaporation step, the second gas phase is compressed and then used as a heat source for the third evaporation step, i.e., before it is fed to the heat exchanger of the evaporator in which the third evaporation step is carried out. For this purpose, any type of compression can be used, and preferably mechanical vapor recompression (MVR) is carried out.

[0048] Furthermore, the multistage evaporation carried out in step e) preferably further comprises at least a subsequent fourth evaporation step, in which the third liquid phase is introduced into the fourth evaporation step and separated therein into a fourth gas phase and a fourth liquid phase, wherein the third gas phase serves as a heat source in the fourth evaporation step. More specifically, the evaporator in which the fourth evaporation step is carried out comprises a heat exchanger, to which the third gas phase is fed as a heat source to heat the third liquid phase introduced into the fourth evaporator. Preferably, the fourth evaporation step is carried out at an absolute pressure of 10 to 30 kPa, and more preferably at an absolute pressure of 15 to 25 kPa, for example at an absolute pressure of about 20 kPa. Particularly good results are obtained when the pressure difference between the pressure at which the third evaporation step is carried out and the pressure at which the fourth evaporation step is carried out is 30 to 80 kPa, and preferably 50 to 60 kPa. The temperature of the liquid during the fourth evaporation step is preferably 60 to 80 °C. If the fourth evaporation step is the last evaporation step of the multistage evaporation carried out in step e), at least a part of the fourth liquid phase is recycled as a detergent to step c) or serves as a heat source in the first evaporation step.

[0049] Furthermore, in the present embodiment, it is preferred that between the third and fourth evaporation steps, the third gas phase is compressed and then used as the heat source in the fourth evaporation step, that is, then it is fed to the heat exchanger of the evaporator where the fourth evaporation step is carried out. For this purpose, any type of compression can be used, and preferably mechanical vapor recompression (MVR) is carried out.

[0050] According to another aspect, the present invention relates to a device for desulfurizing a crude hydrocarbon composition (such as diesel or kerosene), wherein the device comprises:

[0051] a) A liquid-liquid extraction unit including an inlet line for the oxidized crude hydrocarbon composition, an inlet line for the extractant, an extract outlet line, and a raffinate outlet line,

[0052] b) A washing unit including a raffinate inlet line connected to the raffinate outlet line of the liquid-liquid extraction unit a); a detergent inlet line; a desulfurized hydrocarbon composition outlet line; and a detergent and extractant mixture outlet line,

[0053] c) An extractant recovery unit including: an extractant inlet line connected to the extractant outlet line of the liquid-liquid extraction unit a); a waste composition outlet line; and a purified extractant outlet line connected to the extractant inlet line of the liquid-liquid extraction unit; and

[0054] d) A multi-stage evaporation unit including: an inlet line for the mixture of detergent and extractant connected to the detergent and extractant mixture outlet line of the washing unit b); an extractant outlet line; and a purified detergent outlet line, wherein the purified detergent outlet line is connected to the detergent inlet line of the washing unit b); and wherein the multi-stage evaporation unit includes at least two evaporators.

[0055] Preferably, the inlet line for the oxidized crude hydrocarbon composition of the liquid-liquid extraction unit is connected to the outlet line of the oxidized crude hydrocarbon composition of the reactor, wherein the reactor further includes an inlet line for the crude hydrocarbon composition and an inlet line for the oxidant.

[0056] The liquid-liquid extraction unit a) and the washing unit b) can be two independent units.

[0057] According to a particularly preferred embodiment of the present invention, the liquid-liquid extraction unit a) and / or the washing unit b) includes at least one stirred extraction column, and preferably a stirred countercurrent extraction column. For example, the stirred extraction column includes one or more rotating shafts, and each rotating shaft includes one or more stirrers, and the stirrers are preferably selected from discs, blades, paddles, turbine impellers, fins, and any combination of two or more of the above stirrers.

[0058] In a further development of the inventive concept, it is proposed that the stirred extraction column of the liquid-liquid extraction unit a) and / or the washing unit b) comprises two or more compartments which are separated from one another by static partitions, wherein at least some (and preferably all) of the compartments comprise a rotating shaft which comprises one or more stirrers which are preferably selected from discs, blades, paddles, turbine impellers, fins and any combination of two or more of the above-mentioned stirrers.

[0059] Good results are particularly obtained if the stirred extraction column comprises two or more compartments which are separated from one another by static partitions, wherein at least some and preferably all of the compartments comprise a rotating shaft which comprises one or more stirrers which are preferably selected from discs, blades, paddles, turbine impellers, fins and any combination of two or more of the above-mentioned stirrers.

[0060] According to an alternative embodiment, the liquid-liquid extraction unit a) and the washing unit b) may be comprised in one apparatus.

[0061] In this embodiment, preferably, both the liquid-liquid extraction unit a) and the washing unit b) are comprised in one column which comprises a first type of compartment which is separated from one another by static partitions, wherein each of these compartments comprises a rotating shaft which comprises one or more stirrers which are preferably selected from discs, blades, paddles, turbine impellers, fins and any combination of two or more of the above-mentioned stirrers; and the column further comprises a second type of compartment which is separated from one another by static partitions, wherein each of these compartments comprises a rotating shaft which comprises one or more stirrers which are preferably selected from discs, blades, paddles, turbine impellers, fins and any combination of two or more of the above-mentioned stirrers, wherein the geometry and / or dimensions of one or more of the compartments and / or stirrers of the first type are different from those of the second type. Alternatively, the geometry and / or dimensions of one or more of the compartments and / or stirrers of the first type are the same as those of the second type.

[0062] The extractant recovery unit c) preferably comprises one distillation column, and more preferably two or more distillation columns.

[0063] Alternatively, the extractant recovery unit c) may include a multi-stage evaporation unit. This allows for a reduction in energy consumption and thus a reduction in operating costs. The multi-stage evaporation unit includes at least two evaporators and preferably further includes an extract inlet line, a waste composition outlet line, and an extractant outlet line connected to the extract outlet line of the liquid-liquid extraction unit a). In addition, the extractant recovery unit c) may include one or more (e.g., two) distillation columns, where preferably each distillation column is connected to one or two outlet lines of the multi-stage evaporation unit. The multi-stage evaporation unit included in the extractant recovery unit c) preferably behaves as the multi-stage evaporation unit d) described above and below.

[0064] According to a particularly preferred embodiment of the invention, the multi-stage evaporation unit d) includes a first evaporator and at least a subsequent second evaporator, where the first evaporator includes an inlet line connected to the outlet line of the mixture of detergent and extractant of the washing unit b), a liquid phase outlet line, and a gas phase outlet line, and the second evaporator includes an inlet line connected to the liquid phase outlet line of the first evaporator, a heat exchanger connected to the gas phase outlet line of the first evaporator, a liquid phase outlet line, and a gas phase outlet line, and where, if the multi-stage evaporation unit does not include any further subsequent evaporators, the liquid phase outlet line of the second evaporator (which is subsequently the outlet line of the purified detergent of the multi-stage evaporation unit) is connected to the detergent inlet line of the washing unit b). The first evaporator also preferably includes a heat exchanger.

[0065] Preferably, a compressor is arranged between the first evaporator and the subsequent second evaporator, where the inlet line of the compressor is connected to the gas phase outlet line of the first evaporator, and the outlet line of the compressor is connected to the inlet line of the heat exchanger of the second evaporator, such that the gas phase leaving the first evaporator is compressed before being fed to the heat exchanger of the second evaporator.

[0066] In a further development of the inventive concept, it is proposed that the multi-stage evaporation unit d) further includes at least a subsequent third evaporator, where the third evaporator includes a line connected to the liquid phase outlet line of the second evaporator, a heat exchanger connected to the gas phase outlet line of the second evaporator, a liquid phase outlet line, and a gas phase outlet line, and where, if the multi-stage evaporation unit does not include any other subsequent evaporators, the liquid phase outlet line of the third evaporator (which is subsequently the outlet line of the purified detergent of the multi-stage evaporation unit) is connected to the detergent inlet line of the washing unit b).

[0067] In this embodiment, it is also preferred that a compressor is arranged between the second evaporator and the subsequent third evaporator, wherein the inlet line of the compressor is connected to the gas-phase outlet line of the second evaporator, and the outlet line of the compressor is connected to the inlet line of the heat exchanger of the third evaporator, such that the gas phase leaving the second evaporator is compressed before being fed into the heat exchanger of the third evaporator.

[0068] Good results are particularly obtained when the multi-stage evaporation unit d) further comprises at least a subsequent fourth evaporator, wherein the fourth evaporator comprises an inlet line connected to the liquid-phase outlet line of the third evaporator, a heat exchanger connected to the gas-phase outlet line of the third evaporator, a liquid-phase outlet line and a gas-phase outlet line, wherein if the multi-stage evaporation unit does not comprise any other subsequent evaporators, the liquid-phase outlet line of the fourth evaporator (which is subsequently the purified detergent outlet line of the multi-stage evaporation unit) is connected to the detergent inlet line of the washing unit b).

[0069] In this embodiment, it is also preferred that a compressor is arranged between the third evaporator and the subsequent fourth evaporator, wherein the inlet line of the compressor is connected to the outlet line of the gas phase of the third evaporator, and the outlet line of the compressor is connected to the inlet line of the heat exchanger of the fourth evaporator, such that the gas phase leaving the third evaporator is compressed before being fed into the heat exchanger of the fourth evaporator.

[0070] Preferably, the heat exchanger of each evaporator of the multi-stage evaporation unit d) comprises an inlet line for the gas phase and an outlet line for the gas phase and / or the liquid phase, and the outlet lines for the gas phase and / or the liquid phase of all the heat exchangers of the multi-stage evaporation unit d) are merged into the outlet line for the detergent of the multi-stage evaporation unit.

[0071] Furthermore, it is preferred that the extractant outlet line of the multi-stage evaporation unit is connected to the inlet line of a distillation column, which also comprises an outlet line connected to the inlet line of the extractant recovery unit c) and an outlet line connected to the detergent inlet line of the washing unit b).

[0072] Subsequently, the present invention is described by way of illustrative but non-limiting drawings, in which:

[0073] Figure 1 is a schematic view of a device for desulfurizing a crude hydrocarbon composition according to an embodiment of the present invention.

[0074] Figure 2 is Figure 1 a schematic view of the multi-stage evaporation unit of the device shown.

[0075] Figure 3a and 3b is Figure 1Schematic longitudinal sectional view of a part of the liquid-liquid extraction unit of the device shown.

[0076] Figure 4 Is a schematic diagram of a device for desulfurizing a crude hydrocarbon composition according to another embodiment of the present invention.

[0077] Figure 5 Is a schematic diagram of a device for desulfurizing a crude hydrocarbon composition according to another embodiment of the present invention.

[0078] Figure 1 The device 10 for desulfurizing a crude hydrocarbon composition shown includes: a reactor 12 for reacting a crude hydrocarbon composition containing at least one sulfur-containing compound with an oxidant; a liquid-liquid extraction unit 14 for performing liquid-liquid extraction on the oxidized crude hydrocarbon composition obtained in the reactor 12 using an extractant; a washing unit 16 for washing the raffinate obtained in the liquid-liquid extraction unit 14; an extractant recovery unit 18 including two distillation towers 20, 20' for recovering the extractant from the extract obtained from the liquid-liquid extraction unit 14; and a multi-stage evaporation unit 22 for separating the extractant from the detergent. In addition, the device 10 further includes two liquid-liquid separators 24, 26 and a distillation tower 28 for recovering the detergent.

[0079] More specifically, the reactor 12 includes an inlet line 30 for the crude hydrocarbon composition, an oxidant inlet line 32, and an outlet line 34 for the oxidized crude hydrocarbon composition. In addition, the liquid-liquid extraction unit 14 includes an inlet line 36 for the oxidized crude hydrocarbon composition connected to the outlet line 34 of the reactor 12, an extractant inlet line 38, an extract outlet line 40, and a raffinate outlet line 42. In turn, the washing unit 16 includes a raffinate inlet line 44 connected to the raffinate outlet line 42 of the liquid-liquid extraction unit 14, a detergent inlet line 46, a desulfurized hydrocarbon composition outlet line 48, and an outlet line 50 for the mixture of the detergent and the extractant. The outlet line 48 of the desulfurized hydrocarbon composition leads to the inlet line 52 of the liquid-liquid separator 24, which includes a product outlet line 54 for the desulfurized hydrocarbon composition and an outlet line 56 for the detergent, while the outlet line 50 of the mixture of the detergent and the extractant of the washing unit 16 leads to the multi-stage evaporation unit 22. More specifically, the multi-stage evaporation unit 22 includes: an inlet line 58 for the mixture of the detergent and the extractant, which is connected to the outlet line 50 of the mixture of the detergent and the extractant of the washing unit 16; an extractant outlet line 60; and a detergent outlet line 62. As shown in Figure 3, the multi-stage evaporation unit 22 includes four evaporators. In addition, the detergent outlet line 62 of the multi-stage evaporation unit 22 and the detergent outlet line 56 of the liquid-liquid separator 24 are connected to a detergent circulation line 64, which leads to the detergent inlet line 46 of the washing unit 16.

[0080] The extract outlet line 40 of the liquid-liquid extraction unit 14 leads to the first distillation column 20 of the extractant recovery unit 18. More specifically, the first distillation column 20 includes an extract inlet line 66, which is connected to the extract outlet line 40 of the liquid-liquid extraction unit 14, and also includes an extractant outlet line 68 and a waste outlet line 70. The waste outlet line 70 leads to the outside of the device 10, while the extractant outlet line 68 is connected to the second distillation column 20' of the extractant recovery unit 18. More specifically, the second distillation column 20' includes an extractant inlet line 72, which is connected to the extractant outlet line 68 of the first distillation column 20, and also includes a detergent-rich stream outlet line 74 and an extractant outlet line 76, where the extractant outlet line 76 is connected to an extractant circulation line 78, and this circulation line 78 leads to the extractant inlet line 38 of the liquid-liquid extraction unit 14. The outlet line 74 of the detergent-rich stream of the second distillation column 20' leads to an inlet line 80 of the liquid-liquid separator 26, and this liquid-liquid separator 26 includes a waste outlet line 82 and a detergent outlet line 84, and this detergent outlet line 84 is connected to a detergent circulation line 64, and this detergent circulation line 64 leads to the detergent inlet line 46 of the washing unit 16.

[0081] Finally, the extractant outlet line 60 of the multi-stage evaporation unit 22 is connected to an inlet line 86 of the distillation column 28 for further recovering the detergent remaining in the extractant. Among them, the distillation column 28 for recovering the detergent also includes a detergent outlet line 88 and an extractant outlet line 90. The detergent outlet line 88 is connected to the detergent circulation line 64, and this detergent circulation line 64 leads to the detergent inlet line 46 of the washing unit 16; while the extractant outlet line 90 leads to the first distillation column 20 of the extractant recovery unit 18.

[0082] During operation of the apparatus 10, a crude hydrocarbon composition (e.g., diesel) containing a sulfur-containing compound (e.g., thiophene) is fed, together with an oxidant, via line 30 to the reactor 12, where the sulfur-containing compound is mainly oxidized to a sulfone. The oxidized crude hydrocarbon composition thus obtained is fed via lines 34, 36 to a liquid-liquid extraction unit, and the extractant is also fed to the liquid-liquid extraction unit via line 38. During the liquid-liquid extraction process, the oxidized sulfur-containing compound dissolves in the extractant and is thus removed from the hydrocarbons of the crude hydrocarbon composition, resulting in an extract rich in the oxidized sulfur-containing compound and a raffinate poor in the oxidized sulfur-containing compound. The extract is fed via lines 40, 66 to the first distillation column of the extractant recovery unit 18, while the raffinate is fed via lines 42, 44 to the washing unit 16, where the raffinate containing some extractant as an impurity is washed with a detergent (e.g., water), which is fed to the washing unit 16 through the inlet line 46, to remove the extractant from the raffinate. Thereby, the extractant dissolves in the detergent, resulting in a desulfurized hydrocarbon composition and a mixture of the detergent and the extractant in the washing unit 16. The mixture of the detergent and the extractant is discharged from the washing unit 16 through line 50, the desulfurized hydrocarbon composition is discharged from the washing unit 16 through the outlet line 48 and enters the liquid-liquid separator 24 through the inlet line 52, where the remaining detergent separates from the hydrocarbon under the action of gravity, so that the purified desulfurized hydrocarbon composition is discharged from the liquid-liquid separator 24 as a product through the outlet line 54, and the detergent is discharged from the liquid-liquid separator 24 through the outlet line 56. The discharged detergent is recycled through the recycle line 64 to the detergent inlet line 46 and enters the washing unit 16 from there. The mixture of the detergent and the extractant discharged from the washing unit 16 through the outlet line 50 is introduced through the inlet line 58 into the multi-stage evaporation unit 22, where the extractant is separated from the detergent, thereby obtaining the recovered detergent and extractant. The detergent is at least partially recycled through lines 62, 64, 46 to the washing unit 16, while the extractant is introduced through lines 60, 86 into the distillation column 28, where the extractant is further separated from the remaining detergent. The detergent thus obtained is recycled via lines 88, 64, 46 to the washing unit 16, while the remaining extractant is fed via line 90 to the first distillation column 20 of the extractant recovery unit 18. In addition, the extract obtained in the liquid-liquid extraction step carried out in the liquid-liquid extraction column 14 is fed via lines 40, 66 to the first distillation column 20 of the extractant recovery unit 18, where compounds having a boiling point higher than that of the extractant are obtained as a bottom waste composition, which is discharged from the apparatus 10 through the outlet line 70, and the extractant is fed via lines 68, 72 to the second distillation column 20' of the extractant recovery unit 18.Here, the detergent and other compounds with boiling points lower than the extractant are separated from the extractant and discharged as an overhead distillate stream from the second distillation column 20' through line 74, while the recovered extractant is obtained as a bottoms stream and recycled to the liquid-liquid extraction column 14 through lines 76, 78, 38. Finally, the overhead distillate stream discharged from the second distillation column 20' of the extractant recovery unit 18 through line 74 is fed into the liquid-liquid separator 26 through the inlet line 80, where the detergent is separated from the lighter waste by gravity. The lighter waste is discharged from the apparatus 10 through the outlet line 82, and the detergent thus obtained is fed into the washing unit 16 through lines 84, 64, 46.

[0083] Figure 2 is shown in more detail Figure 1 the multi-stage evaporation unit 22 of the apparatus 10 shown. Thus, the multi-stage evaporation unit 22 includes four evaporators 92, 92', 92", 92"'. The first evaporator 92 includes: an inlet line 58, which is connected to the outlet line 50 of the mixture of detergent and extractant of the washing unit 16; a liquid-phase outlet line 96; a vapor-phase outlet line 98; and a heat exchanger 100, wherein the heat exchanger 100 includes an inlet 102 and an outlet 104 for an external heating medium. The second evaporator 92' includes an inlet line 106 connected to the liquid-phase outlet line 96 of the first evaporator 92, and the heat exchanger 108 includes an inlet line 110 and an outlet line 112 connected to the vapor-phase outlet line 98 of the first evaporator 92, wherein the second evaporator 92' also includes a liquid-phase outlet line 114 and a vapor-phase outlet line 116. Similarly, the third evaporator 92" includes an inlet line 118 connected to the liquid-phase outlet line 114 of the second evaporator 92', and the heat exchanger 120 includes an inlet line 122 and an outlet line 124 connected to the vapor-phase outlet line 116 of the second evaporator 92', wherein the third evaporator 92" also includes a liquid-phase outlet line 126 and a vapor-phase outlet line 128. Similarly, the fourth evaporator 92"' includes an inlet line 130 connected to the liquid-phase outlet line 126 of the third evaporator 92", and the heat exchanger 132 includes an inlet line 134 and an outlet line 136 connected to the vapor-phase outlet line 128 of the third evaporator 92", wherein the fourth evaporator 92"' also includes a detergent outlet line 62 and a vapor-phase outlet line 138. As described above, the detergent outlet line 62 is connected to the inlet of the washing unit 16 through lines 62, 64, 46. Upstream of the inlet lines of the second to fourth evaporators 92', 92", 92"', i.e., in the inlet lines 110, 122, 134, a compressor (not shown) can be arranged to compress the vapor before feeding it to the downstream heat exchangers 108, 120, 132.

[0084] During the operation of the multi-stage evaporation unit 22, the mixture of the detergent and the extractant obtained in the washing step carried out in the washing unit 16 is fed through the inlet line 58 to the first evaporator 92, where the mixture is partially evaporated by the heat introduced by the heat exchanger 100, forming a gas phase mainly composed of the extractant and a liquid phase of the detergent and the remaining extractant. The liquid phase is discharged from the first evaporator 92 through the outlet line 96 and fed through the inlet line 106 to the second evaporator 92'; the gas phase is discharged from the first evaporator 92 through the outlet line 98 and fed through the inlet line 110 to the heat exchanger 108 to heat the liquid phase in the second evaporator 92'. The liquid phase is discharged from the second evaporator 92' through the outlet line 114 and introduced through the inlet line 118 into the third evaporator 92''; while the gas phase is discharged from the second evaporator 92' through the outlet line 116 and fed through the inlet line 122 to the heat exchanger 120 to heat the liquid phase contained in the third evaporator 92''. The liquid phase is discharged from the third evaporator 92'' through the outlet line 126 and introduced through the inlet line 130 into the fourth evaporator 92'''; the gas phase is discharged from the third evaporator 92'' through the outlet line 128 and fed through the inlet line 134 to the heat exchanger 132 to heat the liquid phase in the fourth evaporator 92'''. The first evaporation step is carried out at 200 to 400 kPa, the second evaporation step is carried out at an absolute pressure of 100 to 150 kPa, the third evaporation step is carried out at an absolute pressure of 50 to 150 kPa, and the fourth evaporation step is carried out at an absolute pressure of 10 to 30 kPa. The liquid phase or the detergent is obtained in the fourth evaporator 92''' respectively and is discharged from the fourth evaporator 92''' through the line 62 and recycled to the washing step carried out in the washing unit 16 as the detergent.

[0085] Figure 3a and 3b schematically show respectively Figure 1 longitudinal sectional views of a part of the liquid-liquid extraction column 14 or the liquid-liquid extraction unit 14 of the device 10 shown. The edge of the liquid-liquid extraction unit 14 is surrounded by the wall 139 and includes a plurality of compartments 140, 140', 140'', Figure 3a three of which are shown therein, and Figure 3bOne is shown therein. Each compartment 140, 140', 140” is separated from an adjacent compartment 140, 140', 140” by static partitions 142, 142', 142”, 142”'. Each of the static partitions 142, 142', 142”, 142”' is perforated (not shown in the figure), i.e., includes a plurality of holes, allowing liquid to pass from one side of the partitions 142, 142', 142”, 142”' to the other side. In addition, the liquid-liquid extraction unit 14 includes a rotating shaft 144 that extends through each compartment 140, 140', 140” and, when viewed in a longitudinal section, is located at the center of the compartments 140, 140', 140”. The rotating shaft 144 includes a number of turbine impellers as agitators 146, and each compartment 140, 140', 140” includes two agitators 146.

[0086] As Figure 3b shown in more detail, Figure 3b shows Figure 3a a cross-section of the liquid-liquid extraction column 14 highlighted in the frame 148. During operation of the liquid-liquid extraction column 14, the oxidized crude hydrocarbon composition flows through the liquid-liquid extraction column 14 in the directions of arrows 150, 152', while the extractant flows in the opposite direction shown by arrows 152, 150'. The mixture of the oxidized crude hydrocarbon composition and the extractant is agitated by the rotating agitators 146. Among them, the perforated partitions 142, 142', 142” limit the rapid flow in the longitudinal direction. Therefore, when viewed in a longitudinal section, an elliptical flow pattern as shown by arrows 154, 154' is formed. Thus, close contact between the oxidized crude hydrocarbon composition and the extractant is achieved, resulting in the particularly effective extraction of the oxidized sulfur-containing compounds from the hydrocarbon composition into the extractant.

[0087] Figure 4 The crude hydrocarbon composition desulfurization device 10 shown corresponds to Figure 1 the device shown, except that the extractant recovery unit 18 includes not only two distillation columns but also a multi-stage evaporation unit 22'. During operation of the device 10, the extract discharged from the liquid-liquid extraction unit 14 is introduced into the multi-stage evaporation unit 22' via the outlet pipeline 40 and separated into a liquid phase and a gas phase therein. The liquid phase is discharged from the multi-stage evaporation unit 22' and fed to the first distillation column 20 via the connecting pipeline 156. In this distillation column, the liquid phase is separated into a bottom composition containing heavy components and a top distillate composition containing the extractant and water. The top distillate composition is introduced into the second distillation column 20' via pipelines 68”, 72”, while the bottom composition is discharged from the first distillation column 20 via the waste pipeline 70. The gas phase is discharged from the multi-stage evaporation unit 22' and introduced into the second distillation column 20' via pipelines 68', 72'.

[0088] Figure 5The apparatus 10 for desulfurization of a crude hydrocarbon composition shown corresponds to Figure 4 that shown, except that the liquid - liquid extraction unit 14 and the washing unit 16 are combined in a tower 158. The tower 158 includes (not shown) a first type of compartment separated from each other by static partitions, where each of these compartments includes a rotating shaft having one or more agitators, the agitators preferably selected from discs, blades, paddles, turbine impellers, fins, and any combination of two or more of the above - mentioned agitators; and a second type of compartment separated from each other by static partitions, where each of these compartments includes a rotating shaft having one or more agitators, the agitators preferably selected from discs, blades, paddles, turbine impellers, fins, and any combination of two or more of the above - mentioned agitators, wherein the geometry and / or dimensions of one or more compartments and / or agitators of the first type of compartment are different from those of the second type of compartment. During operation of the apparatus 10, the oxidized crude hydrocarbon composition is fed through the inlet line 36 to the bottom of the combined liquid - liquid extraction unit and washing unit 158 and flows upward through the entire combined liquid - liquid extraction unit and washing unit 158, from which it is discharged through the outlet line 48 and thus fed through the inlet line 52 to the liquid - liquid separator 24. The extractant is fed through the inlet line 38 to the middle of the combined liquid - liquid extraction unit and washing unit 158 and sent in a direction opposite to that of the oxidized crude hydrocarbon composition to the bottom of the combined liquid - liquid extraction unit and washing unit 158, and the spent extractant is discharged therefrom through the outlet line 40. During the liquid - liquid extraction process, since the oxidized crude hydrocarbon composition flows upward from the oxidized crude hydrocarbon composition inlet to the bottom of the combined liquid - liquid extraction unit and washing unit 158 and the extractant inlet is in the middle of the combined liquid - liquid extraction unit and washing unit 158, oxidized sulfur - containing compounds are removed from the oxidized crude hydrocarbon composition, and the oxidized crude hydrocarbon composition is obtained as a raffinate in the middle of the combined liquid - liquid extraction unit. The raffinate thus obtained further flows upward through the combined liquid - liquid extraction unit and washing unit 158, where it contacts the detergent, which is fed through the inlet lines 46, 64 to the upper part of the combined liquid - liquid extraction unit and washing unit 158 and flows upward through the combined liquid - liquid extraction unit and washing unit 158 in a direction opposite to that of the raffinate. Thereby, trace amounts of the extractant are removed from the raffinate, resulting in a desulfurized hydrocarbon composition, which is removed from the combined liquid - liquid extraction unit and washing unit 158 through the outlet line 48, while the mixture of the detergent and the extractant is discharged from the combined liquid - liquid extraction unit and washing unit 158 through the outlet line 50. The outlet line 50 is arranged at a position directly above the extractant inlet 38.

[0089] Reference numerals

[0090] 10 apparatus

[0091] 12 Reactor

[0092] 14 Liquid-liquid extraction unit

[0093] 16 Washing unit

[0094] 18 Extractant recovery unit

[0095] 20, 20’ Distillation columns of the extractant recovery unit

[0096] 22, 22' Multi-stage evaporation unit

[0097] 24 Liquid-liquid separator

[0098] 26 Liquid-liquid separator

[0099] 28 Distillation column for recovering detergent

[0100] 30 Inlet pipeline for crude hydrocarbon composition

[0101] 32 Inlet pipeline for oxidant

[0102] 34 Outlet pipeline for oxidized crude hydrocarbon composition

[0103] 36 Inlet pipeline for oxidized crude hydrocarbon composition

[0104] 38 Inlet pipeline for extractant

[0105] 40 Outlet pipeline for extractant

[0106] 42 Outlet pipeline for raffinate

[0107] 44 Inlet pipeline for raffinate

[0108] 46 Inlet pipeline for detergent

[0109] 48 Outlet pipeline for desulfurized hydrocarbon composition

[0110] 50 Outlet pipeline for mixture of detergent and extractant

[0111] 52 Inlet pipeline for liquid-liquid separator 24

[0112] 54 Outlet pipeline for desulfurized hydrocarbon composition product

[0113] 56 Outlet pipeline for detergent

[0114] 58 Inlet pipeline for mixture of detergent and extractant

[0115] 60 Outlet pipeline for extractant

[0116] 62 Outlet pipeline for detergent

[0117] 64 Detergent circulation pipeline

[0118] 66 Extract inlet pipeline

[0119] 68, 68', 68'' Extractant outlet pipeline

[0120] 70 Waste outlet pipeline

[0121] 72, 72', 72'' Extractant inlet pipeline

[0122] 74 Outlet pipeline for the detergent-rich stream

[0123] 76 Extractant outlet pipeline

[0124] 78 Recycling pipeline for the recovered extractant

[0125] 80 Inlet pipeline 28 for the liquid-liquid separator

[0126] 82 Waste outlet pipeline

[0127] 84 Detergent outlet pipeline

[0128] 86 Inlet pipeline for the distillation column of the recovered detergent

[0129] 88 Detergent outlet pipeline

[0130] 90 Extractant outlet pipeline

[0131] 92, 92', 92'', 92''' Evaporators of the multi-stage evaporation unit

[0132] 96 Liquid-phase outlet pipeline of the first evaporator

[0133] 98 Vapor-phase outlet pipeline of the first evaporator

[0134] 100 Heat exchanger of the first evaporator

[0135] 102 Inlet pipeline for the heat exchanger of the first evaporator

[0136] 104 Outlet pipeline for the heat exchanger of the first evaporator

[0137] 106 Inlet pipeline for the second evaporator

[0138] 108 Heat exchanger of the second evaporator

[0139] 110 Inlet pipeline for the heat exchanger of the second evaporator

[0140] 112 Outlet pipeline for the heat exchanger of the second evaporator

[0141] 114 Liquid-phase outlet pipeline of the second evaporator

[0142] 116 Second evaporator vapor outlet pipeline

[0143] 118 Third evaporator inlet pipeline

[0144] 120 Heat exchanger of the third evaporator

[0145] 122 Heat exchanger inlet pipeline of the third evaporator

[0146] 124 Heat exchanger outlet pipeline of the third evaporator

[0147] 126 Third evaporator liquid outlet pipeline

[0148] 128 Third evaporator vapor outlet pipeline

[0149] 130 Fourth evaporator inlet pipeline

[0150] 132 Heat exchanger of the fourth evaporator

[0151] 134 Heat exchanger inlet pipeline of the fourth evaporator

[0152] 136 Heat exchanger outlet pipeline of the fourth evaporator

[0153] 138 Fourth evaporator vapor outlet pipeline

[0154] 139 Liquid-liquid extraction unit wall

[0155] 140, 140', 140” Compartments of the liquid-liquid extraction unit

[0156] 142, 142', 142”, 142”' Static partitions

[0157] 144 Rotating shaft

[0158] 146 Agitator

[0159] 148 Figure 3b Part of the shown liquid-liquid extraction unit

[0160] 150, 152' Arrows indicating the flow direction of the oxidized crude hydrocarbon composition

[0161] 152, 150' Arrows indicating the flow direction of the extractant

[0162] 154, 154' Arrows indicating the flow pattern inside the compartment

[0163] 156 Connecting line

[0164] 157 Outlet pipeline

[0165] 158 Combined Liquid-Liquid Extraction Unit and Washing Unit

Claims

1. A method for desulfurizing a crude hydrocarbon composition such as diesel or kerosene, wherein the method comprises the following steps: a) providing an oxidized crude hydrocarbon composition containing at least one oxidized sulfur compound, b) subjecting the oxidized crude hydrocarbon composition provided in step a) to liquid-liquid extraction with an extractant to obtain an extract rich in at least one oxidized sulfur compound and a raffinate poor in at least one oxidized sulfur compound, c) washing the raffinate obtained in step b) with a detergent to remove the remaining extractant from the raffinate, thereby obtaining a desulfurized hydrocarbon composition and a mixture of the detergent and the extractant, d) subjecting the extract obtained in step b) to at least one purification step to obtain a purified extractant and a waste composition, wherein the purified extractant is at least partially recycled to step b), and e) subjecting the mixture of the detergent and the extractant obtained in step c) to multi-stage evaporation to separate the extractant from the detergent, thereby obtaining a purified detergent, wherein the purified detergent is at least partially recycled to step c), and wherein the multi-stage evaporation comprises at least two successive evaporation steps, wherein the first evaporation step is carried out at a higher pressure than at least one of the subsequent evaporation steps.

2. The method according to claim 1, wherein the oxidized crude hydrocarbon composition provided in step a) is produced by reacting the crude hydrocarbon composition with an oxidizing agent, and the crude hydrocarbon composition is selected from diesel, kerosene, gasoline, naphtha, vacuum gas oil, light cycle oil, heavy cycle oil, marine gas oil, marine diesel, marine fuel oil, residue, lubricating oil, and any combination of two or more of the above compositions.

3. The method according to claim 1 or 2, wherein the extractant used in step b) is an aprotic and / or polar extractant, which is preferably selected from methanol, acetonitrile, N-methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, furfural, sulfolane, and any combination of two or more of the above compounds.

4. The method according to any one of the preceding claims, wherein the liquid-liquid extraction in step b) is carried out in a stirred extraction column, and preferably in a countercurrent stirred extraction column, wherein the stirred extraction column comprises two or more compartments separated from each other by static partitions, wherein at least some, and preferably all, of the compartments comprise a rotating shaft, and the rotating shaft comprises one or more stirrers, and the stirrers are preferably selected from discs, blades, paddles, turbine impellers, fins, and any combination of two or more of the above stirrers.

5. The method according to any one of the preceding claims, wherein at least one of the following is satisfied, preferably at least two, more preferably at least three, still more preferably at least four, and most preferably all five: i) Liquid-liquid extraction b) is carried out in a stirred extraction column, which comprises one or more rotating shafts, each rotating shaft comprising one or more agitators, said agitators being preferably selected from discs, blades, paddles, turbine impellers, fins and any combination of two or more of the above-mentioned agitators, wherein, The rotational speed of one or more rotating shafts is adjusted to 5 to 1,000 rpm, and more preferably 5 to 50 rpm, ii) In the liquid-liquid extraction process carried out in step b), a two-phase system is treated, wherein the extractant forms the continuous phase and the droplets of the oxidized crude hydrocarbon composition are dispersed in this continuous phase, and the extraction column is operated such that the size of the droplets dispersed in the continuous phase is from 0.5 to 10 mm, and more preferably from 1 to 3 mm. iii) In the liquid-liquid extraction carried out in step b), an extractant is used such that the difference in density between the extractant and the oxidized crude hydrocarbon composition is 15 to 400 kg / m 3 , iv) In the liquid-liquid extraction carried out in step b), an extractant is used such that the interfacial tension between the extractant and the oxidized crude hydrocarbon composition is from 0.0005 to 0.07 N / m, measured by the drop volume method using a drop volume tensiometer - DVT50. v) In the liquid-liquid extraction carried out in step b), an extractant having an electric dipole moment of at least 1.5 Debye, preferably at least 3.2 Debye, and more preferably from 3.2 to 4.2 Debye is used.

6. The method according to any one of the preceding claims, wherein the liquid-liquid extraction and the washing step are carried out in one apparatus, which comprises a first compartment for carrying out the liquid-liquid extraction and a second compartment for carrying out the washing step.

7. The method according to any one of the preceding claims, wherein the sulfur compound content of the desulfurized hydrocarbon composition obtained in step c) is at most 20 ppm, and preferably at most 10 ppm, the detergent content is at most 20,000 ppm, and more preferably at most 10,000 ppm, and the extractant content is at most 25,000 ppm, and more preferably at most 11,000 ppm.

8. The method according to any one of the preceding claims, wherein in step d), the extract obtained in step b) is subjected to i) multi-stage evaporation, said multi-stage evaporation comprising at least two successive evaporation steps, wherein the first evaporation step is carried out at a higher pressure than at least one of the subsequent evaporation steps, and / or ii) at least one distillation step, and preferably at least two successive distillation steps are carried out.

9. The multi-stage evaporation carried out in step e) comprises a first evaporation step and at least a subsequent second evaporation step, wherein the mixture of the detergent and the extractant obtained in step c) is introduced into the first evaporation step and separated therein into a first gas phase and a first liquid phase, wherein the first liquid phase is introduced into the second evaporation step and separated therein into a second gas phase and a second liquid phase, wherein the first gas phase is used as a heat source in the second evaporation step, wherein the first evaporation step is carried out at an absolute pressure of 200 to 400 kPa, and preferably at an absolute pressure of 250 to 300 kPa, wherein the second evaporation step is carried out at an absolute pressure of 100 to 250 kPa, and preferably at an absolute pressure of 160 to 230 kPa, and wherein if the second evaporation step is the last evaporation step of the multi-stage evaporation carried out in step e), at least a part of the second liquid phase is recycled as the detergent to step c) or used as a heat source in the first evaporation step.

10. The method according to claim 9, wherein The multistage evaporation carried out in step e) further comprises at least a subsequent third evaporation step, in which the second liquid phase is introduced into the third evaporation step and separated therein into a third gas phase and a third liquid phase, wherein the second gas phase is used as a heat source in the third evaporation step, wherein the third evaporation step is carried out at an absolute pressure of 50 to 150 kPa, and preferably at an absolute pressure of 70 to 130 kPa, wherein, if the third evaporation step is the last evaporation step of the multistage evaporation carried out in step e), at least a part of the third liquid phase is recycled as a detergent to step c) or used as a heat source in the first evaporation step, wherein, preferably, the multistage evaporation carried out in step e) further comprises at least a subsequent fourth evaporation step, in which the third liquid phase is introduced into the fourth evaporation step and separated therein into a fourth gas phase and a fourth liquid phase, wherein the third gas phase is used as a heat source in the fourth evaporation step, wherein the fourth evaporation step is carried out at an absolute pressure of 10 to 30 kPa, and preferably at an absolute pressure of 15 to 25 kPa, and wherein, if the fourth evaporation step is the last evaporation step of the multistage evaporation carried out in step e), at least a part of the fourth liquid phase is recycled as a detergent to step c) or used as a heat source in the first evaporation step.

11. An apparatus for desulfurizing a crude hydrocarbon composition such as diesel or kerosene, wherein the apparatus comprises: a) a liquid-liquid extraction unit comprising an inlet line for an oxidized crude hydrocarbon composition, an inlet line for an extractant, an extract outlet line, and a raffinate outlet line; b) a washing unit comprising: a raffinate inlet line connected to the raffinate outlet line of the liquid-liquid extraction unit a); a detergent inlet line; a desulfurized hydrocarbon composition outlet line; and a mixture outlet line for the detergent and the extractant; c) an extractant recovery unit comprising: an extractant inlet line connected to the extractant outlet line of the liquid-liquid extraction unit a); a waste composition outlet line; and a purified extractant outlet line connected to the extractant inlet line of the liquid-liquid extraction unit; and d) a multistage evaporation unit comprising: an inlet line for a mixture of the detergent and the extractant, which is connected to the mixture outlet line of the detergent and the extractant of the washing unit b); an extractant outlet line; and a purified detergent outlet line, wherein the purified detergent outlet line is connected to the detergent inlet line of the washing unit b); and wherein the multistage evaporation unit comprises at least two evaporators.

12. The apparatus according to claim 11, wherein the liquid-liquid extraction unit a) and / or the washing unit b) comprises at least one stirred column, and preferably a countercurrent stirred column, wherein the stirred column comprises two or more compartments separated from each other by static partitions, wherein at least some, and preferably all, of the compartments comprise a rotating shaft, the rotating shaft comprising one or more stirrers, the stirrers preferably being selected from discs, blades, paddles, turbine impellers, fins, and any combination of two or more of the above stirrers.

13. The device according to claim 11 or 12, wherein both the liquid-liquid extraction unit a) and the washing unit b) are included in a column, which column comprises a first type of compartment separated from each other by static partitions, wherein each of these compartments comprises a rotating shaft, which rotating shaft comprises one or more agitators, which agitators are preferably selected from discs, blades, paddles, turbine impellers, fins, and any combination of two or more of the above-mentioned agitators; and the column further comprises a second type of compartment separated from each other by static partitions, wherein each of these compartments comprises a rotating shaft, which rotating shaft comprises one or more agitators, which agitators are preferably selected from discs, blades, paddles, turbine impellers, fins, and any combination of two or more of the above-mentioned agitators, wherein the geometry and / or dimensions of one or more compartments and / or agitators of the first type of compartment may be the same as or different from those of the second type of compartment.

14. The device according to any one of claims 11 to 13, wherein the extractant recovery unit c) comprises i) a multi-stage evaporation unit, which unit comprises at least two evaporators, an extract inlet line connected to the extract outlet line of the liquid-liquid extraction unit a), a waste composition outlet line, and an extractant outlet line, and / or ii) one, two, or more distillation columns.

15. The device according to any one of claims 11 to 14, wherein, The multi-stage evaporation unit d) comprises a first evaporator and at least a subsequent second evaporator, wherein the first evaporator comprises an inlet line connected to the outlet line of the mixture of the detergent and the extractant of the washing unit b), a liquid phase outlet line, and a gas phase outlet line, wherein the second evaporator comprises an inlet line connected to the liquid phase outlet line of the first evaporator, a heat exchanger connected to the gas phase outlet line of the first evaporator, a liquid phase outlet line, and a gas phase outlet line, wherein if the multi-stage evaporation unit does not comprise any further subsequent evaporators, the liquid phase outlet line of the second evaporator is connected to the detergent inlet line of the washing unit b), wherein preferably, the multi-stage evaporation unit d) further comprises at least a subsequent third evaporator, wherein the third evaporator comprises an inlet line connected to the liquid phase outlet line of the second evaporator, a heat exchanger connected to the gas phase outlet line of the second evaporator, a liquid phase outlet line, and a gas phase outlet line, wherein if the multi-stage evaporation unit does not comprise any further subsequent evaporators, the liquid phase outlet line of the third evaporator is connected to the detergent inlet line of the washing unit b), and wherein preferably the multi-stage evaporation unit d) further comprises at least a subsequent fourth evaporator, wherein the fourth evaporator comprises an inlet line connected to the liquid phase outlet line of the third evaporator, a heat exchanger connected to the gas phase outlet line of the third evaporator, a liquid phase outlet line, and a gas phase outlet line, wherein if the multi-stage evaporation unit does not comprise any further subsequent evaporators, the liquid phase outlet line of the fourth evaporator is connected to the detergent inlet line of the washing unit b).

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