Aromatic hydrocarbon separation device

Abstract

The utility model provides an aromatic hydrocarbon separation device which comprises an extractive distillation tower and a solvent recovery tower, the bottom of the extractive distillation tower is connected with the solvent recovery tower through a connecting pipe, the bottom of the solvent recovery tower is connected with the extractive distillation tower through a solvent recovery pipe, and an N-hydroxymethyl phthalimide feeding pipe is arranged on the connecting pipe. A triethanolamine feeding pipe is arranged on the N-hydroxymethyl phthalimide feeding pipe; a triethanolamine feeding pipe is arranged on the N-hydroxymethyl phthalimide feeding pipe; a sulfolane inlet pipe, an N-hydroxymethyl phthalimide inlet pipe, a triethanolamine inlet pipe and a crude aromatic hydrocarbon inlet pipe are arranged on one side of the extractive distillation tower; the bottom of the solvent recovery tower is connected with the extractive distillation tower through a solvent recovery pipe. The device can improve the recovery rate of aromatic hydrocarbon and is simple in structure.

Description

Technical Field

[0001] The utility model belongs to the technical field of aromatic hydrocarbon separation, in particular to an aromatic hydrocarbon separation device. Background Art

[0002] Crude aromatics are mainly derived from hydrocarbon thermal cracking to ethylene units, catalytic reforming units, etc. Aromatics is an important organic chemical raw material with a very broad market prospect. It is mainly used in the production of plastics, chemical fibers, pesticides, rubber, dyes and other fields.

[0003] At present, aromatic separation mainly includes extractive distillation process and liquid-liquid extraction process. The principle of liquid-liquid extraction is to separate aromatics by using the different solubility of solvents in aromatics and non-aromatics. According to the different solvents used, the process can be divided into Udex method, sulfolane method (Sulfolane), N-methylpyrrolidone method (Arosolvan), dimethyl sulfoxide method (DMSO) and N-formylmorpholine method (Formex), etc. Among them, the most widely used is the sulfolane method (Sulfolane). The liquid-liquid extraction process has a long process flow, a backwashing step is set, and the energy consumption is high. The extractive distillation process uses the addition of solvents to change the relative volatility of aromatics and non-aromatics to separate aromatics, and mainly uses sulfolane as a solvent. The extractive distillation process has the characteristics of short process, simple operation, low investment and small footprint. Therefore, the newly built aromatic separation units in recent years mostly use the extractive distillation process. A single solvent has limited effect on changing the relative volatility of aromatic and non-aromatic hydrocarbons, but a composite solvent obtained by adding other substances can greatly improve the relative volatility of aromatic and non-aromatic hydrocarbons. Utility Model Content

[0004] In view of this, the utility model aims to provide an aromatics separation device to solve the problem of low aromatics recovery rate.

[0005] In order to achieve the above object, the technical solution of the utility model is implemented as follows:

[0006] An aromatic hydrocarbon separation device comprises an extractive distillation tower and a solvent recovery tower. The bottom of the extractive distillation tower is connected to the solvent recovery tower through a connecting pipe, the bottom of the solvent recovery tower is connected to the extractive distillation tower through the solvent recovery pipe, the connecting pipe is provided with an N-hydroxymethylphthalimide feeding pipe, and the N-hydroxymethylphthalimide feeding pipe is provided with a triethanolamine feeding pipe; a sulfolane inlet pipe, an N-hydroxymethylphthalimide inlet pipe, a triethanolamine inlet pipe and a crude aromatic hydrocarbon inlet pipe are provided on one side of the extractive distillation tower; and the bottom of the solvent recovery tower is connected to the extractive distillation tower through the solvent recovery pipe.

[0007] Further, the top of the extractive distillation tower is connected to the first buffer tank through a first buffer tube;

[0008] The bottom of the first buffer tank is connected to the extractive distillation tower through a first reflux pipe, and the first reflux pipe is provided with a residual oil extraction pipe.

[0009] Furthermore, a first reboiler is provided on the first buffer tube.

[0010] Furthermore, the connecting pipe is connected to the extractive distillation tower via a second reflux pipe;

[0011] The second reflux pipe is provided with a second reboiler.

[0012] Furthermore, the top of the solvent recovery tower is connected to the second buffer tank through a second buffer pipe.

[0013] Furthermore, a third reboiler is provided on the second buffer tube.

[0014] Furthermore, the upper part of the second buffer tank is connected to the vacuum system through a vacuum connecting pipe.

[0015] Furthermore, the bottom of the second buffer tank is connected to the solvent recovery tower through a third reflux pipe, and the third reflux pipe is provided with an aromatics outlet pipe.

[0016] Furthermore, the bottom of the solvent recovery pipe is connected to the solvent recovery pipe through a fourth reflux pipe.

[0017] Furthermore, a fourth reboiler is provided on the fourth reflux pipe.

[0018] Compared with the prior art, the aromatics separation device described in the utility model has the following advantages:

[0019] 1. The present invention is used to separate aromatics from naphtha, and the recovery rate of aromatics is high. The structure of the present invention is simple, and the recovery rate of aromatics can be above 99.6%;

[0020] 2. This device further increases the relative volatility of aromatics and non-aromatics by setting up a sulfolane inlet tube, an N-hydroxymethylphthalimide inlet tube, and a triethanolamine inlet tube, and can reduce the solvent-oil ratio in the aromatic separation process, reduce the solvent circulation volume, and reduce energy consumption.

[0021] 3. The present application is provided with a first buffer tank and a second buffer tank, which can buffer the produced liquid at the top of the extractive distillation tower and the solvent recovery tower. The raffinate oil is discharged from the extractive distillation tower through the first buffer tank, and the aromatics are produced from the top of the solvent recovery tower through the second buffer tank for post-processing.

[0022] 4. The bottoms of the extraction distillation tower and the solvent recovery tower of the present application are respectively provided with a second reboiler and a fourth reboiler, which can improve the utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the accompanying drawings:

[0024] Figure 1 It is an overall schematic diagram of an aromatic hydrocarbon separation device described in an embodiment of the utility model.

[0025] Description of reference numerals:

[0026] 1. Extraction distillation tower; 2. Solvent recovery tower; 3. Connecting pipe; 4. Solvent recovery pipe; 5. N-hydroxymethylphthalimide feeding pipe; 6. Triethanolamine feeding pipe; 7. Sulfolane inlet pipe; 8. N-hydroxymethylphthalimide inlet pipe; 9. Triethanolamine inlet pipe; 10. Crude aromatics inlet pipe; 11. First buffer pipe; 12. First buffer tank; 13. First reflux pipe; 14. Extraction oil outlet pipe; 15. First reboiler; 16. Second reflux pipe; 17. Second reboiler; 18. Second buffer pipe; 19. Second buffer tank; 20. Third reboiler; 21. Vacuum connecting pipe; 22. Vacuum system; 23. Third reflux pipe; 24. Aromatics outlet pipe; 25. Fourth reflux pipe; 26. Fourth reboiler. DETAILED DESCRIPTION

[0027] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0028] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0029] An aromatic hydrocarbon separation device comprises an extractive distillation tower 1 and a solvent recovery tower 2. The bottom of the extractive distillation tower 1 is connected to the solvent recovery tower 2 through a connecting pipe 3, and the bottom of the solvent recovery tower 2 is connected to the extractive distillation tower 1 through a solvent recovery pipe 4. The connecting pipe 3 is provided with an N-hydroxymethylphthalimide feeding pipe 5, and the N-hydroxymethylphthalimide feeding pipe 5 is provided with a triethanolamine feeding pipe 6; one side of the extractive distillation tower 1 is provided with a sulfolane inlet pipe 7, an N-hydroxymethylphthalimide inlet pipe 8, a triethanolamine inlet pipe 9 and a crude aromatic hydrocarbon inlet pipe 10; the bottom of the solvent recovery tower 2 is connected to the extractive distillation tower 1 through the solvent recovery pipe 4. The top of the extractive distillation tower 1 is connected to the first buffer tank 12 through a first buffer pipe 11; the bottom of the first buffer tank 12 is connected to the extractive distillation tower 1 through a first reflux pipe 13, and the first reflux pipe 13 is provided with a raffinate oil outlet pipe 14. The first buffer pipe 11 is provided with a first reboiler 15. The connecting pipe 3 is connected to the extractive distillation tower 1 through the second reflux pipe 16; the second reflux pipe 16 is provided with a second reboiler 17. The top of the solvent recovery tower 2 is connected to the second buffer tank 19 through the second buffer pipe 18. The second buffer pipe 18 is provided with a third reboiler 20. The top of the second buffer tank 19 is connected to the vacuum system 22 through the vacuum connecting pipe 213. The bottom of the second buffer tank 19 is connected to the solvent recovery tower 2 through the third reflux pipe 23, and the third reflux pipe 23 is provided with an aromatics outlet pipe 24. The bottom of the solvent recovery pipe 4 is connected to the solvent recovery pipe 4 through the fourth reflux pipe 25. The fourth reflux pipe 25 is provided with a fourth reboiler 26.

[0030] 85wt%-98wt% sulfolane, 1wt%-10wt% N-hydroxymethylphthalimide, 1wt%-5wt% triethanolamine are added to an extractive distillation tower, and the residual oil is discharged from the top of the tower, and the sulfolane, N-hydroxymethylphthalimide, and triethanolamine rich in aromatics enter the solvent recovery tower from the bottom of the tower through a connecting pipe, and the connecting pipeline is provided with an N-hydroxymethylphthalimide feed pipe and a triethanolamine feed pipe, and aromatics are extracted from the top of the solvent recovery tower for post-processing, and sulfolane, N-hydroxymethylphthalimide, and triethanolamine are returned to the extractive distillation tower from the bottom of the solvent recovery tower through a solvent recovery pipe. The present application significantly improves the solubility of aromatics, and the aromatic recovery rate is more than 99.6%. The top temperature of the extractive distillation tower is 75°C to 105°C, the bottom temperature is 155°C to 165°C, and the operating pressure is 0.03 to 0.25 MPaG, preferably 0.05 to 0.1 MPaG. The top temperature of the solvent recovery tower is 55°C to 87°C, the bottom temperature is 170°C to 179°C, and the operating pressure is -0.03 to -0.07 MPaG, preferably -0.04 to -0.05 MPaG.

[0031] Example 1

[0032] By using the above-mentioned device of the present application, crude aromatics are added into the extractive distillation tower from the lower part, 95wt% of sulfolane, 3% of N-hydroxymethylphthalimide and 2wt% of triethanolamine are added into the extractive distillation tower from the upper part, the raffinate oil is discharged from the top of the tower, and the mixed solvent of aromatics, sulfolane, N-hydroxymethylphthalimide and triethanolamine enters the solvent recovery tower from the bottom of the tower through a connecting pipe, and the connecting pipe is provided with an N-hydroxymethylphthalimide feeding pipe and a triethanolamine feeding pipe.

[0033] The operating conditions of the extractive distillation tower are: solvent-oil ratio 4.2:1, tower top temperature 96°C, tower bottom temperature 158°C, and pressure 0.05MPa. The top temperature of the solvent recovery tower is 82°C, the tower bottom temperature is 175°C, and the pressure is -0.05MPaG. At this time, the aromatics yield is 99.7%.

[0034] Example 2

[0035] By using the above-mentioned device of the present application, crude aromatics are added into the extractive distillation tower from the lower part, 95wt% of sulfolane, 4% of N-hydroxymethylphthalimide and 1wt% of triethanolamine are added into the extractive distillation tower from the upper part, the raffinate oil is discharged from the top of the tower, and the mixed solvent of aromatics, sulfolane, N-hydroxymethylphthalimide and triethanolamine enters the solvent recovery tower from the bottom of the tower through a connecting pipe, and the connecting pipe is provided with an N-hydroxymethylphthalimide feeding pipe and a triethanolamine feeding pipe.

[0036] The operating conditions of the extractive distillation tower are: solvent-oil ratio 4.2:1, tower top temperature 96°C, tower bottom temperature 158°C, and pressure 0.05MPa. The top temperature of the solvent recovery tower is 82°C, the tower bottom temperature is 173°C, and the pressure is -0.05MPaG. At this time, the aromatics yield is 99.8%.

[0037] Example 3

[0038] The difference from Example 2 is that when the catalyst-oil ratio is reduced to 3.7:1, the aromatics yield is still greater than 99.8%.

[0039] Comparative Example 1

[0040] The crude aromatics are added to the extractive distillation tower from the lower part, 95wt% sulfolane and 5% N-hydroxymethylphthalimide (the difference from the device in Example 1 is that triethanolamine is not provided) are added from the upper part of the extractive distillation tower, the raffinate is discharged from the top of the tower, the aromatics, sulfolane and N-hydroxymethylphthalimide are discharged from the bottom of the tower and enter the solvent recovery tower, and only the N-hydroxymethylphthalimide feeding pipe is provided on the connecting pipe;

[0041] The operating conditions of the extractive distillation tower are: solvent-oil ratio 4.2:1, tower top temperature 97°C, tower bottom temperature 158°C, and pressure 0.05MPa. The top temperature of the solvent recovery tower is 82°C, the tower bottom temperature is 175°C, and the pressure is -0.05MPaG. At this time, the aromatics yield is 99.6%.

[0042] project Agent-oil ratio Alkanes Cycloalkanes Aromatics Raw material crude aromatics% 15.5 9.6 74.8 Comparative Example 1, Raffinate Oil % 4.2:1 60.7 38.32 0.98 Comparative Example 2, Raffinate Oil % 4.2:1 60.4 38.11 0.49 Comparative Example 3, Raffinate Oil % 4.2:1 59.9 37.9 2.2 Example 1, Raffinate Oil % 4.2:1 60.9 38.51 0.59 Example 2, Raffinate Oil % 4.2:1 61.0 38.63 0.37 Example 3, Raffinate Oil % 3.7:1 60.9 38.5 0.60

[0043] Comparative Example 2

[0044] The crude aromatics are added to the extractive distillation tower from the lower part, 99wt% sulfolane and 1wt% triethanolamine (the difference from the device in Example 1 is that no N-hydroxymethylphthalimide feed pipe is set) are added from the upper part of the extractive distillation tower, the raffinate is discharged from the top of the tower, and the aromatics, sulfolane and triethanolamine are discharged from the bottom of the tower into the solvent recovery tower. Only the triethanolamine feed pipe is set on the connecting pipe; the operating conditions of the extractive distillation tower are: agent-oil ratio 4.2:1, tower top temperature 96°C, tower bottom temperature 158°C, and pressure 0.05MPa. The solvent recovery tower has a top temperature of 82°C, a bottom temperature of 174°C, and a pressure of -0.05MPaG. At this time, the aromatic yield is 99.7%.

[0045] Comparative Example 3

[0046] A single sulfolane solvent (the difference from Example 1 is that no N-hydroxymethylphthalimide feeding tube and no triethanolamine feeding tube are provided), and an extractive distillation tower is used to separate aromatic hydrocarbons from the crude aromatic hydrocarbon component. Crude aromatic hydrocarbons are added to the extractive distillation tower from the lower part, sulfolane is added from the upper part of the extractive distillation tower, the raffinate is discharged from the top of the tower, and the solvent rich in aromatic hydrocarbons is discharged from the bottom of the tower into the solvent recovery tower, and no N-hydroxymethylphthalimide feeding tube and triethanolamine feeding tube are provided on the connecting pipeline;

[0047] The operating conditions of the extractive distillation tower are: solvent-oil ratio 4.2:1, tower top temperature 98°C, tower bottom temperature 162°C, and pressure 0.05MPa. The top temperature of the solvent recovery tower is 84°C, the tower bottom temperature is 175°C, and the pressure is -0.05MPaG. At this time, the aromatics yield is 99%.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An aromatics separation device, characterized in that: It comprises an extractive distillation tower and a solvent recovery tower, wherein the bottom of the extractive distillation tower is connected to the solvent recovery tower through a connecting pipe, and the bottom of the solvent recovery tower is connected to the extractive distillation tower through a solvent recovery pipe, wherein an N-hydroxymethylphthalimide feeding pipe is provided on the connecting pipe, and a triethanolamine feeding pipe is provided on the N-hydroxymethylphthalimide feeding pipe; One side of the extractive distillation tower is provided with a sulfolane inlet pipe, an N-hydroxymethylphthalimide inlet pipe, a triethanolamine inlet pipe and a crude aromatic hydrocarbon inlet pipe; The bottom of the solvent recovery tower is connected to the extraction distillation tower through a solvent recovery pipe.

2. An aromatics separation device according to claim 1, characterized in that: The top of the extractive distillation tower is connected to the first buffer tank through a first buffer tube; The bottom of the first buffer tank is connected to the extractive distillation tower through a first reflux pipe, and the first reflux pipe is provided with a residual oil extraction pipe.

3. An aromatics separation device according to claim 2, characterized in that: The first buffer tube is provided with a first reboiler.

4. The aromatics separation device according to claim 1, characterized in that: The connecting pipe is connected to the extractive distillation tower via a second reflux pipe; The second reflux pipe is provided with a second reboiler.

5. The aromatics separation device according to claim 1, characterized in that: The top of the solvent recovery tower is connected to the second buffer tank through a second buffer pipe.

6. The aromatics separation device according to claim 5, characterized in that: The second buffer tube is provided with a third reboiler.

7. The aromatics separation device according to claim 5, characterized in that: The upper part of the second buffer tank is connected to the vacuum system through a vacuum connecting pipe.

8. The aromatics separation device according to claim 5, characterized in that: The bottom of the second buffer tank is connected to the solvent recovery tower through a third reflux pipe, and the third reflux pipe is provided with an aromatics outlet pipe.

9. The aromatics separation device according to claim 1, characterized in that: The bottom of the solvent recovery pipe is connected to the solvent recovery pipe through the fourth reflux pipe.

10. An aromatics separation device according to claim 9, characterized in that: The fourth reflux pipe is provided with a fourth reboiler.

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