CN116948685A - Composite solvent, method and device for simultaneously separating naphthenes and aromatic hydrocarbons from naphtha - Google Patents

Abstract

The invention discloses a composite solvent, a method and a device suitable for simultaneously separating naphthenes and aromatic hydrocarbons from naphtha. The composite solvent is composed of dimethyl sulfoxide (I), cucurbituril (II) and 1-ethyl- It is composed of 3-methylimidazole ethyl sulfate salt (III). The mass ratio of the three is I:II:III=(85～96):(3～14):1. This compound solvent is very effective for naphthenes. The selectivity to cycloalkanes can reach 6.27, and the mass removal rate of naphthenes can reach 71.34%; the selectivity to aromatics can reach 36.16, and the mass removal rate of aromatic hydrocarbons can reach 91.51%. The characteristic of the present invention is that the special structure and characteristics of cucurbituril are used to enrich cyclic compounds such as naphtha and aromatic hydrocarbons in the bottom of the reactor, and rapid separation is achieved by setting a filter at the bottom of the extraction tower.

Description

Composite solvent, method and device for simultaneously separating naphthenes and aromatic hydrocarbons from naphtha

Technical field

The present invention relates to the technical field of separating naphthenic hydrocarbons and aromatic hydrocarbons from naphtha, and in particular, to a composite solvent for simultaneously separating naphthenic hydrocarbons and aromatic hydrocarbons from naphtha, as well as methods and devices for using the composite solvent.

Background technique

In the petrochemical production process, naphtha is an important chemical raw material, which is mainly composed of normal alkanes, isoparaffins, cycloalkanes and aromatic hydrocarbons. Among them, the yield of ethylene produced by cracking normal alkanes and isoparaffins is relatively high. High, it is an ideal raw material for ethylene cracking. After the cracking of cycloalkanes, higher yields of propylene and butadiene can be obtained, but the yield of ethylene is not high, and its proportion in the ethylene cracking raw material needs to be controlled; in addition, cycloalkanes can also be easily converted into ethylene under reforming conditions. Aromatic hydrocarbons. Therefore, naphthenes are suitable as raw materials for ethylene cracking and catalytic reforming. Aromatic hydrocarbons do not contribute to the yield of ethylene during cracking and are prone to coking, shortening the production cycle of the device. Therefore, aromatic hydrocarbons are not suitable for ethylene cracking. raw material.

At present, the industry mainly uses light and heavy cutting to separate hydrocarbon mixtures. The disadvantage of this method is that it cannot effectively separate according to components, and cannot achieve "aromatic when aromatic and alkenyl when appropriate", resulting in insufficient separation of raw materials. Make the most of it.

In addition, the prior art has studied the adsorption separation and extraction separation of naphtha. CN1476474A and CN1710030A disclose methods for selectively separating n-alkanes from naphtha through adsorption separation. Although these methods can obtain ethylene cracking feedstock rich in n-alkanes, they mainly separate n-alkanes or aromatics from naphtha, and cannot simultaneously separate naphthenes/aromatics from naphtha.

CN104945328A discloses a method of using ionic liquids to separate aromatic hydrocarbons from diesel fuel, CN101265152A discloses a method of using ionic liquids to separate cyclohexane and benzene, and CN102405084A discloses a method of using ionic liquids to separate aromatic hydrocarbon isomers. Method, the above technology shows that the use of ionic liquids to separate mixtures of substances has the advantages of strong pertinence and high efficiency. Based on the composition characteristics of naphtha, a composite solvent containing ionic liquids is developed to simultaneously separate naphthenes/aromatics from naphtha. is feasible. For this reason, CN110229692A discloses a method for simultaneously separating naphthenes/aromatics from naphtha using a composite solvent containing ionic liquids. However, in actual operation, it was found that some ionic liquids will still be entrained in the raffinate oil, resulting in Loss of ionic liquid may occur during subsequent separation processes.

Contents of the invention

Based on the problems existing in the prior art, the purpose of the present invention is to provide a composite solvent, method and device for simultaneously separating naphtha/aromatic hydrocarbons from naphtha. The composite solvent of the present invention is added with cucurbituril, ionic liquid, etc. It forms a composite solvent and uses the special structure and characteristics of cucurbituril to enrich cyclic compounds such as naphthenes and aromatics in naphtha, which not only strengthens the effect of simultaneously separating naphthenes/aromatics from naphtha, but also maximizes the It avoids the loss and loss problems that may be caused by the ionic liquid entering the subsequent separation process.

In order to achieve the above object, the present invention provides a composite solvent for simultaneously separating naphthenes and aromatic hydrocarbons from naphtha. The composite solvent is composed of dimethyl sulfoxide, cucurbituril and 1-ethyl-3-methylimidazole sulfate. It is composed of ethyl ester salt, and the mass ratio of the three is 85~96:3~14:1. The composite solvent for simultaneously separating naphtha/aromatic hydrocarbons from naphtha uses dimethyl sulfoxide (component I) as the main solvent, and its main function is to separate aromatic hydrocarbons from naphtha. Add an appropriate proportion of cucurbituril (component II) and 1-ethyl-3-methylimidazole sulfate ethyl ester salt (component III) to dimethyl sulfoxide (component I). The main function is to remove stone from the stone at the same time. Separates naphthenes/aromatics from brain oil, and can flexibly adjust the separation ratio of naphthenes. The composite solvent of the present invention has adjustable characteristics, that is, the extraction performance of separating naphthenic hydrocarbons and aromatic hydrocarbons can be adjusted through the preparation ratio of the components. The composite solvent is prepared at a constant temperature within the range of 40 to 100°C. The composite solvent can extract and separate naphtha at 60-100°C and 0.01-1.0MPa, and separate part or all of the naphtha/aromatic hydrocarbons from the naphtha as needed.

The invention also provides a method for simultaneously separating naphthenic hydrocarbons and aromatic hydrocarbons from naphtha. The method includes the following steps: mixing the above-mentioned composite solvent with naphtha and then filtering, and the filtered stream is rich in naphthenic hydrocarbons and aromatic hydrocarbons. .

In the method of the present invention, the mass ratio of the composite solvent to the naphtha is 2 to 8:1, preferably 2 to 6:1.

In the method of the present invention, the mixing temperature is 60-100°C and the pressure is 0.01-1.0MPa.

In the method of the present invention, the mixing temperature is 70-90°C and the pressure is 0.02-0.5MPa.

The method of the present invention also includes the following steps: the filtrate stream separates naphthenes and aromatic hydrocarbons through vacuum distillation to obtain a regenerated composite solvent, and the regenerated composite solvent is recycled.

In the method of the present invention, the temperature of the vacuum distillation is 60 to 100°C, preferably 70 to 90°C, and the pressure is -0.01 to -0.08MPa, preferably -0.02 to -0.06MPa.

The invention also provides a device for simultaneously separating naphthenes and aromatic hydrocarbons from naphtha, which is characterized in that it includes an extraction tower and a vacuum distillation tower, and the top and bottom of the extraction tower are respectively provided with raffinate oil outlets. and a discharge port, a filter is provided above the discharge port, a composite solvent inlet and a raw oil inlet are respectively provided at the upper and lower parts of the extraction tower, and an extraction port is provided at the top and bottom of the vacuum distillation tower. The oil outlet and the regenerated composite solvent outlet are provided with a mixed material inlet in the middle of the vacuum distillation tower, and the mixed material inlet is connected with the discharge port.

The device of the present invention further includes a mixer, and the outlet of the mixer is connected with the composite solvent inlet or the regenerated composite solvent outlet.

In the device of the present invention, the mixer is a static mixer, and the operating temperature of the static mixer is constant at 40-100°C.

The composite solvent of the present invention is composed of cucurbituril and ionic liquid by adding cucurbituril to form a composite solvent. The special structure and characteristics of cucurbituril are used to enrich cyclic compounds such as naphtha and aromatic hydrocarbons in naphtha, that is, to strengthen the extraction of naphtha from naphtha. The effect of simultaneously separating naphthenic hydrocarbons/aromatic hydrocarbons in the process also avoids the loss and loss problems that may be caused by ionic liquid entering the subsequent separation process to the greatest extent. The selectivity and mass removal rate of the composite solvent of the present invention for naphthenes in naphtha can reach 6.27 and 71.34% respectively, and the selectivity and mass removal rate of aromatic hydrocarbons in naphtha can reach 36.16 and 91.51%.

Description of the drawings

Figure 1 is a schematic diagram of a device for simultaneously separating naphthenes and aromatic hydrocarbons from naphtha according to the present invention.

in,

1. Extraction tower,

11. Exhaust oil outlet,

12. Composite solvent entrance

13. Naphtha feed inlet,

14. Filter,

2. Vacuum distillation tower,

21. Pull out the oil outlet,

22. Inlet for naphthenic-rich materials,

3. Static mixer,

31. Dimethyl sulfoxide entrance,

32. The entrance of cucurbituril,

33. 1-ethyl-3-methylimidazole ethyl sulfate salt entrance.

Detailed ways

The following is a detailed description of the embodiments of the present invention: This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation modes and processes are given. However, the protection scope of the present invention is not limited to the following examples. Experimental methods that do not indicate specific conditions in the examples usually follow conventional conditions.

Referring to Figure 1, Figure 1 is a schematic diagram of a device for simultaneously separating naphthenes and aromatics from naphtha according to the present invention. The device includes an extraction tower 1 and a vacuum distillation tower 2. The top of the extraction tower 1 is provided with a raffinate outlet 11 and a composite solvent inlet 12 respectively. A filter 14 is provided at the bottom of the extraction tower. A naphtha is provided at the bottom of the extraction tower. Oil feed inlet 13. The top of the vacuum distillation tower 2 is provided with an extraction oil outlet 21, and the middle part of the vacuum distillation tower is provided with a naphthenic-rich material inlet 22. The naphthenic-rich material inlet 22 is connected to the discharge port of the extraction tower 1. The device also includes a static mixer 3, the outlet of the static mixer 3 is connected with the composite solvent inlet 12.

Referring to Figure 1, the method for simultaneously separating naphthenes and aromatic hydrocarbons from naphtha provided by the present invention includes the following steps: dimethyl sulfoxide (component I) is removed from the dimethyl sulfoxide inlet 31, cucurbituril (component I) Part II) enters the static mixer from the cucurbituril inlet 32 and 1-ethyl-3-methylimidazole ethyl sulfate salt (component III) respectively from the 1-ethyl-3-methylimidazole ethyl sulfate salt inlet 33 3. After thorough mixing, introduce it into the extraction tower 1 from the composite solvent inlet 12 at the upper part of the extraction tower 1, and make counter-current contact with the carbon hydrocarbon mixture raw material entering from the naphtha feed inlet 13 at the lower part of the extraction tower 1; after liquid-liquid extraction, Finally, the top stream of extraction tower 1 is the raffinate from which part of the naphthenes and aromatics have been removed, while most of the naphthenes and aromatics and all the composite solvents are concentrated in the lower part of the extraction tower 1. Different from the traditional process, during the extraction A filter 14 is designed and installed above the discharge port at the bottom of the extraction tower 1. The bottom of the extraction tower 1 can be divided into two areas. The area above the filter 14 is a rich cucurbituril area, and the area below the filter 14 is a poor cucurbituril area. The partitioning of the cucurbituril zone and the lean cucurbituril zone can prevent cucurbituril from entering the vacuum distillation tower and causing unnecessary blockage. The stream in the cucurbituril-lean zone below the bottom filter 14 of the extraction tower 1 is rich in naphthenes and aromatic hydrocarbons, and is led to the vacuum distillation tower 2 through the discharge port. After vacuum distillation in the vacuum distillation tower 2, the pressure is reduced. The stream flowing out of the bottom of distillation tower 2 (regenerated composite solvent) is circulated to the composite solvent inlet 12 of extraction tower 1, mixed with the fresh composite solvent coming out of static mixer 3, and then enters extraction tower 1 together. The top of vacuum distillation tower 2 The stream is extracted oil (a mixture of naphthenes and aromatic hydrocarbons), which can be used as raw material for catalytic reforming or for other purposes.

The extraction and separation performance of the composite solvent refers to the solubility performance of the composite solvent for naphthenes and aromatic hydrocarbons in naphtha under a certain agent-to-oil ratio, and is characterized by selectivity and removal rate parameters.

Selectivity is calculated using the following formula:

In the formula, S represents selectivity, C _i ^{extracted oil} and C _j ^{extracted oil} respectively represent the mass concentrations of i and j components in the extracted oil, C _i ^{raffinate oil} and C _j ^{raffinate oil} respectively represent the concentrations of i and j components in the extracted oil. Mass concentration in raffinate oil.

The removal rate is calculated using the following formula:

In the formula, P% represents the removal rate, C _i ^{extracted oil} represents the mass concentration of component i in the extracted oil, C _i ^{raw oil} represents the mass concentration of component i in the raw oil, and β represents the yield of raffinate oil.

Example 1

Mix dimethyl sulfoxide (component I), cucurbituril (component II) and 1-ethyl-3-methylimidazole sulfate ethyl ester salt (component III) in static mixer 3 in a proportion of Component I: Component II: Component III = 85:14:1 (mass), the naphtha is extracted and separated according to the process of Figure 1, wherein the mass ratio of the composite solvent to the naphtha raw oil is 2: 1; The operating conditions of static mixer 3 are: temperature 60°C; the operating conditions of extraction tower 1 are: temperature 80°C, pressure 0.20MPa; the operating conditions of vacuum distillation tower 2 are: temperature 70°C, pressure 0.04MPa.

The composition of the naphtha used is shown in Table 1, the extraction operation parameters are shown in Table 2, and the composition of the raffinate oil and extracted oil is shown in Table 3.

Example 2

Mix dimethyl sulfoxide (component I), cucurbituril (component II) and 1-ethyl-3-methylimidazole sulfate ethyl ester salt (component III) in static mixer 3 in a proportion of Component I: Component II: Component III = 91:8:1 (mass), the naphtha is extracted and separated according to the process of Figure 1, wherein the mass ratio of the composite solvent to the naphtha raw oil is 2: 1; The operating conditions of static mixer 3 are: temperature 60°C; the operating conditions of extraction tower 1 are: temperature 80°C, pressure 0.20MPa; the operating conditions of vacuum distillation tower 2 are: temperature 70°C, pressure 0.04MPa.

The composition of the naphtha used is shown in Table 1, the extraction operation parameters are shown in Table 2, and the composition of the raffinate oil and extracted oil is shown in Table 3.

Example 3

Mix dimethyl sulfoxide (component I), cucurbituril (component II) and 1-ethyl-3-methylimidazole sulfate ethyl ester salt (component III) in static mixer 3 in a proportion of Component I: Component II: Component III = 96:3:1 (mass), the naphtha is extracted and separated according to the process of Figure 1, wherein the mass ratio of the composite solvent to the naphtha raw oil is 2: 1; The operating conditions of static mixer 3 are: temperature 60°C; the operating conditions of extraction tower 1 are: temperature 80°C, pressure 0.20MPa; the operating conditions of vacuum distillation tower 2 are: temperature 70°C, pressure 0.04MPa.

The composition of the naphtha used is shown in Table 1, the extraction operation parameters are shown in Table 2, and the composition of the raffinate oil and extracted oil is shown in Table 3.

Comparative example 1

This comparative example is basically the same as Example 2, with special features:

The composite solvent is composed of dimethyl sulfoxide (component I) and 1-ethyl-3-methylimidazole sulfate ethyl ester salt (component III). The ratio is component I:component III=99:1 ( quality). Among them, the mass ratio of the composite solvent to the naphtha feed oil is 2:1; the operating conditions of the static mixer 3 are: temperature 60°C; the operating conditions of the extraction tower 1 are: temperature 80°C, pressure 0.30MPa; reduced pressure The operating conditions of distillation tower 2 are: temperature 70°C, pressure 0.04MPa.

The composition of the naphtha used is shown in Table 1, the extraction operation parameters are shown in Table 2, and the composition of the raffinate oil and extracted oil is shown in Table 3.

Comparative example 2

This comparative example is basically the same as Example 2, with special features:

Sulfolane (component I) and 1-ethyl-3-methylimidazole sulfate ethyl ester salt (component III) are compounded in a ratio of I:II=99:1 (mass), in which the compound solvent and naphtha The mass ratio of raw oil is 2:1; the operating conditions of static mixer 3 are: temperature 60°C; the operating conditions of extraction tower 1 are: temperature 100°C, pressure 0.30MPa; the operating conditions of vacuum distillation tower 2 are: Temperature 80℃, pressure 0.05MPa.

The composition of the naphtha used is shown in Table 1, the extraction operation parameters are shown in Table 2, and the composition of the raffinate oil and extracted oil is shown in Table 3.

Table 1 Naphtha composition

project paraffins Naphthenic Alkenes Aromatic hydrocarbons PIONA value, mass % 55.4 30.4 0.1 14.1

Table 2 Extraction process conditions

Table 3 Extraction results

It can be seen from the results in Table 3 that the present invention uses the special structure and characteristics of cucurbituril to enrich cyclic compounds such as naphtha and aromatic hydrocarbons in the naphtha at the bottom of the reactor to achieve rapid separation. Compared with the comparative example without cucurbituril, Ratio, the selectivity of the composite solvent of the present invention to cycloalkanes can reach 6.27, and the mass removal rate of cycloalkanes can reach 71.34%; at the same time, the selectivity of the composite solvent of the present invention to aromatic hydrocarbons can reach 36.16, and the mass removal rate of aromatic hydrocarbons can reach 36.16. The rate can reach 91.51%.

In addition, the present invention installs a filter above the lower outlet of the extraction tower 1, which reduces the possibility of blockage caused by heavy components in subsequent equipment pipelines to a certain extent while ensuring the normal operation of the extraction tower.

Of course, the present invention can also have various other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention. However, these corresponding changes and deformations shall all fall within the protection scope of the present invention.

Claims (10)

1. The composite solvent is characterized by comprising dimethyl sulfoxide, cucurbituril and 1-ethyl-3-methylimidazole ethyl sulfate salt, wherein the mass ratio of the dimethyl sulfoxide to the cucurbituril to the ethyl-3-methylimidazole ethyl sulfate salt is 85-96:3-14:1.

2. A process for simultaneously separating naphthenes and aromatics from naphtha comprising the steps of: the composite solvent of claim 1 is mixed with naphtha and then filtered, and the filtrate stream is enriched in naphthenes and aromatics.

3. The method for simultaneously separating naphthenes and aromatics from naphtha according to claim 2, wherein the mass ratio of said complex solvent to said naphtha is 2-8:1, preferably 2-6:1.

4. The method for simultaneously separating naphthenes and aromatics from naphtha according to claim 2, wherein said mixing is at a temperature of 60-100 ℃ and a pressure of 0.01-1.0 MPa.

5. The method for simultaneously separating naphthenes and aromatics from naphtha according to claim 4, wherein said mixing is performed at a temperature of 70-90 ℃ and a pressure of 0.02-0.5 MPa.

6. The method for simultaneously separating naphthenes and aromatics from naphtha according to claim 2, further comprising the steps of: and separating naphthene and aromatic hydrocarbon from the filtrate flow through reduced pressure distillation to obtain regenerated composite solvent, wherein the regenerated composite solvent is recycled.

7. The process for simultaneous separation of naphthenes and aromatics from naphtha according to claim 6, wherein said reduced pressure distillation is carried out at a temperature of 60-100 ℃, preferably 70-90 ℃, and at a pressure of-0.01 to-0.08 MPa, preferably-0.02 to-0.06 MPa.

8. The device for simultaneously separating naphthene and aromatic hydrocarbon from naphtha comprises an extraction tower and a reduced pressure distillation tower, wherein a raffinate oil outlet and a discharge port are respectively arranged at the top and the bottom of the extraction tower, a filter is arranged above the discharge port, a composite solvent inlet and a raw oil inlet are respectively arranged at the upper part and the middle part of the extraction tower, an extract oil outlet and a regenerated composite solvent outlet are respectively arranged at the top and the bottom of the reduced pressure distillation tower, a mixture inlet is arranged at the middle part of the reduced pressure distillation tower, and the mixture inlet is communicated with the discharge port.

9. The apparatus for simultaneously separating naphthenes and aromatics from naphtha according to claim 8, further comprising a mixer, an outlet of said mixer being in communication with said complex solvent inlet or said regenerated complex solvent outlet.

10. The apparatus for simultaneously separating naphthenes and aromatics from naphtha according to claim 9, wherein said mixer is a static mixer whose operating temperature is constant at 40-100 ℃.