Normal hexane separation and purification device
By combining a benzene removal tower, a hexane fractionation tower, and a hexane stripping tower, the problem of efficiently separating high-purity n-hexane was solved, enabling the production of high-purity n-hexane, simplifying the process flow, and reducing resource consumption and costs.
Patent Information
- Application Number
- CN202423283593.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-12-30
- Estimated Expiration
- 2034-12-30
AI Technical Summary
Existing technologies are insufficient for efficiently separating and purifying high-purity n-hexane, resulting in high benzene content, which fails to meet market demand for high-end n-hexane products. Furthermore, the operation process is complex and resource consumption is high.
A combined process of benzene removal tower, hexane fractionation tower, hexane stripping tower and n-isohexane fractionation tower is adopted. Through reverse extraction and multi-stage fractionation, benzene is removed first and then n-hexane is separated and purified, which simplifies the process and reduces resource consumption.
It achieves the separation of high-purity n-hexane and isohexane, with a purity of 99.5 wt% and a benzene content of less than 0.001 wt%, which simplifies the process, reduces equipment investment and operating costs, and improves stability and safety.
Smart Images
Figure CN223732131U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of n-hexane separation technology, specifically to an n-hexane separation and purification device. Background Technology
[0002] A typical aromatics extraction process usually includes a hexane fractionation tower. The raffinate from the extraction section enters the hexane fractionation tower for separation. The hexane fractionation tower also has a mid-section side-stream hexane stripping tower. The separated hexane product is usually a mixture of n-hexane and isohexane, with a high benzene content, and cannot be used directly.
[0003] Hexane has a wide range of applications, including in the food, pharmaceutical, chemical, polymer materials, and rubber industries. As an extractant in the edible oil industry, hexane requires a narrow hexane solvent oil fraction and a low benzene content, as these two indicators directly affect the quality, yield, and energy consumption of the edible oil. High-purity hexane is often used to prepare standard solutions for gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Therefore, there is a large market demand for high-purity, low-benzene-content high-end hexane products.
[0004] The main feedstocks for producing n-hexane include aromatic raffinate, reformed oil, or cracked and hydrogenated gasoline. The compounds in these feedstocks have relatively similar boiling points; for example, n-hexane and benzene readily form azeotropes, which cannot be directly separated by conventional distillation processes. Currently, a combined distillation and hydrogenation process is primarily used. This process is suitable for low benzene content conditions, but the operation is complex and the purity of the produced n-hexane is generally below 90%, which cannot meet the needs of the domestic market. High-purity n-hexane still relies on imports. Therefore, developing high-purity n-hexane production processes and technologies is of great significance. Utility Model Content
[0005] The purpose of this invention is to provide a hexane separation and purification device to solve the problems mentioned in the background art.
[0006] To achieve the above objectives, this utility model provides the following technical solution:
[0007] A hexane separation and purification apparatus includes the following steps:
[0008] A. The non-aromatic feedstock containing low concentration of benzene raffinate from the upstream aromatics extraction unit enters the middle and lower part of the benzene stripping tower. Solvent oil is injected into the top of the benzene stripping tower and comes into countercurrent contact with the non-aromatic feedstock containing raffinate from the aromatics extraction unit. The benzene in the non-aromatic feedstock is extracted into the solvent. The benzene-rich solvent oil at the bottom of the benzene stripping tower is sent to the extraction distillation tower of the extraction unit to continue to be used as a solvent. The non-aromatic feedstock at the top of the tower is sent to the hexane fractionation tower for separation.
[0009] B. Non-aromatic materials from the benzene removal tower enter the middle section of the hexane fractionation tower. The gaseous material at the top of the tower is condensed by the hexane fractionation tower condenser and then enters the hexane fractionation tower reflux tank. After being pressurized by the hexane fractionation tower reflux pump, part of it is returned to the hexane fractionation tower as top reflux, and part of the light components below C6 are sent out as product. The components above C6 obtained from the bottom separation are sent out as product.
[0010] C. The hexane fractionation tower has a side stream extraction section equipped with a hexane stripping tower. The side stream material extracted from the upper part of the hexane fractionation tower is stripped into the hexane stripping tower. The overhead gas of the hexane stripping tower is returned to the tray above the side stream extraction position of the hexane fractionation tower, and the bottom material is sent to the n-isohexane fractionation tower for further separation.
[0011] D. The material from the bottom of the hexane stripping tower enters the middle of the n-isohexane fractionation tower. The gaseous material from the top of the hexane stripping tower is condensed by the n-isohexane fractionation tower condenser and then enters the n-isohexane fractionation tower reflux tank. After being pressurized by the n-isohexane fractionation tower reflux pump, part of it is returned to the n-isohexane fractionation tower as top reflux, while high-purity isohexane is separated and high-purity n-hexane is obtained at the bottom of the tower.
[0012] As a further embodiment of this utility model: the solvent oil in step A includes one or more of the following composite solvents: sulfolane, glycol, dimethyl sulfoxide, N-methylpyrrolidone or N-formylmorpholine, and the amount of solvent added is 3 to 6 times the amount of feed.
[0013] As a further embodiment of this utility model: the benzene removal tower in step A has 10 to 100 theoretical trays, the top pressure is 0.2 to 2.0 MPa, and the temperature of the solvent oil entering the top of the tower is 40 to 100°C.
[0014] As a further embodiment of this utility model: the hexane fractionation column described in step B has 10 to 100 theoretical trays, a top pressure of 0.05 to 1.0 MPa, a top operating temperature of 40 to 150°C, a condensation system at the top of the hexane fractionation column, and a reboiling system at the bottom of the column.
[0015] As a further embodiment of this utility model: the hexane stripping tower in step C has 5 to 50 theoretical trays, a top pressure of 0.05 to 1.0 MPa, a top operating temperature of 50 to 180°C, and is equipped with a bottom reboiling system.
[0016] As a further embodiment of this utility model: the n-isohexane fractionation column in step D has 10 to 200 theoretical trays, a top pressure of 0.01 to 0.5 MPa, a top operating temperature of 50 to 150°C, a condensation system at the top of the n-isohexane fractionation column, and a reboiling system at the bottom of the column.
[0017] As a further embodiment of this utility model: the n-hexane separation and purification device includes a benzene removal tower, a hexane fractionation tower, a hexane stripping tower, and an n-isohexane fractionation tower, which are connected by pipelines. The benzene removal tower includes a lean solvent oil feed pipeline, a benzene-containing residue oil non-aromatic feed pipeline from the upstream aromatics extraction unit, and a benzene-rich solvent oil delivery pipeline, and is connected to the hexane fractionation tower via a top pipeline. The top of the hexane fractionation tower is connected in sequence by pipelines to a hexane fractionation tower condenser, a hexane fractionation tower reflux tank, a hexane fractionation tower reflux pump, a return pipeline to the top of the tower, and a partial product delivery pipeline. The bottom of the hexane fractionation tower is connected by pipelines. The hexane fractionation tower is connected to the hexane stripping tower reboiler. A product delivery pipeline is located at the bottom of the hexane fractionation tower, and a side line is connected to the hexane stripping tower via a pipeline. The bottom of the hexane stripping tower is connected to the hexane stripping tower reboiler via a pipeline, and the bottom product is connected to the n-isohexane fractionation tower via a pipeline. The top of the n-isohexane fractionation tower is connected in sequence via pipelines to the n-isohexane fractionation tower condenser, the n-isohexane fractionation tower reflux tank, the n-isohexane fractionation tower reflux pump, the return pipeline to the top of the tower, and a portion of the product delivery pipeline. The bottom of the n-isohexane fractionation tower is connected to the n-isohexane fractionation tower reboiler via a pipeline, and a product delivery pipeline is located at the bottom of the n-isohexane fractionation tower.
[0018] Compared with the prior art, the beneficial effects of this utility model are:
[0019] 1. This invention adopts a method of first removing benzene and then separating and purifying n-hexane, eliminating the need for a hydrogenation-separation system, reducing the consumption of resources such as hydrogen, and saving a lot of energy.
[0020] 2. The process flow is simplified, the investment and operating costs of the equipment are reduced, and the stability and safety of the equipment are further improved.
[0021] 3. This invention is for raffinate containing low concentrations of benzene, and can separate high-purity n-hexane and isohexane with a purity >99.5 wt% and a benzene content of less than 0.001 wt%. Attached Figure Description
[0022] The present invention will be further described in detail below with reference to the embodiments shown in the accompanying drawings, but this does not constitute any limitation on the present invention.
[0023] Figure 1 This is a flowchart of a hexane separation and purification device.
[0024] In the diagram: 1. Benzene removal tower; 2. Hexane fractionation tower; 3. Hexane fractionation tower reboiler; 4. Hexane fractionation tower condenser; 5. Hexane fractionation tower reflux tank; 6. Hexane fractionation tower reflux pump; 7. Hexane stripping tower; 8. Hexane stripping tower reboiler; 9. n-Isohexane fractionation tower; 10. n-Isohexane fractionation tower reboiler; 11. n-Isohexane fractionation tower condenser; 12. n-Isohexane fractionation tower reflux tank; 13. n-Isohexane fractionation tower reflux pump. Detailed Implementation
[0025] The technical solution of this patent will be further described in detail below with reference to specific embodiments.
[0026] Please see Figure 1 A hexane separation and purification apparatus includes the following steps:
[0027] A. The non-aromatic feedstock containing low concentration of benzene raffinate from the upstream aromatics extraction unit enters the middle and lower part of the benzene removal tower 1. Solvent oil is injected into the top of the benzene removal tower 1 and comes into countercurrent contact with the non-aromatic feedstock containing raffinate from the aromatics extraction unit. The benzene in the non-aromatic feedstock is extracted into the solvent. The benzene-rich solvent oil at the bottom of the benzene removal tower 1 is sent to the extraction distillation tower of the extraction unit to continue to be used as a solvent. The non-aromatic feedstock at the top of the tower is sent to the hexane fractionation tower 2 for separation.
[0028] B. Non-aromatic materials from the benzene removal tower 1 enter the middle section of the hexane fractionation tower 2. The gaseous material at the top of the tower is condensed by the hexane fractionation tower condenser 4 and then enters the hexane fractionation tower reflux tank 5. After being pressurized by the hexane fractionation tower reflux pump 6, part of it is returned to the hexane fractionation tower 2 as top reflux, and part of the light components below C6 are sent out as products. The components above C6 obtained from the bottom separation are sent out as products.
[0029] C. Hexane fractionation tower 2 has a side stream extraction section equipped with a hexane stripping tower 7. The side stream material extracted from the upper part of the hexane fractionation tower 2 enters the hexane stripping tower 7 for stripping. The top gas of the hexane stripping tower 7 returns to the tray above the side stream extraction position of the hexane fractionation tower 2, and the bottom material is sent to the n-isohexane fractionation tower 9 for further separation.
[0030] D. The material from the bottom of the hexane stripping tower 7 enters the middle of the n-isohexane fractionation tower 9. The gaseous material from the top of the hexane stripping tower 7 is condensed by the n-isohexane fractionation tower condenser 11 and then enters the n-isohexane fractionation tower reflux tank 12. After being pressurized by the n-isohexane fractionation tower reflux pump 13, part of it is returned to the n-isohexane fractionation tower 9 as top reflux, while high-purity isohexane is separated and high-purity n-hexane is obtained at the bottom of the tower.
[0031] Furthermore, the solvent oil mentioned in step A includes one or more of the following composite solvents: sulfolane, glycol, dimethyl sulfoxide, N-methylpyrrolidone, or N-formylmorpholine. The amount of solvent added is 3 to 6 times the feed amount. Sulfolane is preferred as the solvent.
[0032] Furthermore, in step A, the benzene removal tower 1 has 10 to 100 theoretical trays, a top pressure of 0.2 to 2.0 MPa, and a solvent oil inlet temperature of 40 to 100°C. Preferably, the top pressure is 0.3 to 0.8 MPa.
[0033] Furthermore, in step B, the hexane fractionation column 2 has 10 to 100 theoretical trays, a top pressure of 0.05 to 1.0 MPa, and a top operating temperature of 40 to 150°C. The hexane fractionation column 2 is equipped with a condensation system at the top and a reboiling system at the bottom. Preferably, the top pressure is 0.05 to 0.3 MPa.
[0034] Furthermore, in step C, the hexane stripping column 7 has 5 to 50 theoretical trays, a top pressure of 0.05 to 1.0 MPa, and a top operating temperature of 50 to 180°C. The hexane stripping column 7 is equipped with a bottom reboiler system. Preferably, the top pressure is 0.05 to 0.3 MPa.
[0035] Furthermore, in step D, the n-isohexane fractionation column 9 has 10 to 200 theoretical trays, a top pressure of 0.01 to 0.5 MPa, and a top operating temperature of 50 to 150°C. The n-isohexane fractionation column 9 is equipped with a condensation system at the top and a reboiling system at the bottom. Preferably, the top pressure is 0.01 to 0.1 MPa.
[0036] Furthermore, the aforementioned hexane separation and purification device includes a benzene removal tower 1, a hexane fractionation tower 2, a hexane stripping tower 7, and an isohexane fractionation tower 9, all interconnected by pipelines. The benzene removal tower 1 includes a lean solvent oil feed pipeline, a benzene-containing residue oil non-aromatic feed pipeline from an upstream aromatics extraction unit, and a benzene-rich solvent oil delivery pipeline, and is connected to the hexane fractionation tower 2 via a top pipeline. The top of the hexane fractionation tower 2 is sequentially connected via pipelines to a hexane fractionation tower condenser 4, a hexane fractionation tower reflux tank 5, a hexane fractionation tower reflux pump 6, a return pipeline to the top of the tower, and a partial product delivery pipeline. The bottom of the hexane fractionation tower 2 is connected via a pipeline to the hexane stripping tower reboiler 8, and a product delivery pipeline is located at the bottom of the hexane fractionation tower 2, with a side line connected to the hexane stripping tower 7. The bottom of the hexane stripping tower 7 is connected via a pipeline to the hexane stripping tower reboiler 8. The bottom product of the distillation column is connected to the n-isohexane fractionation column 9 via a pipeline; the top of the n-isohexane fractionation column 9 is connected in sequence via pipelines to the n-isohexane fractionation column condenser 11, the n-isohexane fractionation column reflux tank 12, the n-isohexane fractionation column reflux pump 13, the return pipeline to the top of the column, and a partial product delivery pipeline; the bottom of the n-isohexane fractionation column 9 is connected to the n-isohexane fractionation column reboiler 10 via a pipeline; and the bottom of the n-isohexane fractionation column 9 is equipped with a product delivery pipeline.
[0037] The above-described embodiments are preferred embodiments of the present utility model and are only used to facilitate the illustration of the present utility model. They are not intended to limit the present utility model in any way. Any person skilled in the art who makes partial modifications or alterations to the technical content disclosed in the present utility model without departing from the scope of the technical features of the present utility model shall still fall within the scope of the technical features of the present utility model.
Claims
1. A n-hexane separation and purification device comprising a benzene removal column (1), a hexane fractionation column (2), a hexane stripping column (7) and a n-iso-hexane fractionation column (9), which are connected to each other by means of lines, characterized in that: The benzene-stripping column (1) is connected with a hexane fractionation column (2) through an overhead line; the hexane fractionation column (2) is connected with a hexane fractionation column condenser (4), a hexane fractionation column reflux tank (5), a hexane fractionation column reflux pump (6), a return overhead line and a partial product discharge line in sequence through lines at the top of the column; the hexane fractionation column (2) is connected with a hexane stripping column reboiler (8) through a line at the bottom of the column; the hexane fractionation column (2) is provided with a product discharge line at the bottom of the column, and a side line is connected with a hexane stripping column (7) through a line; the hexane stripping column (7) is connected with the hexane stripping column reboiler (8) through a line at the bottom of the column, and the bottom product is connected with a normal and iso-hexane fractionation column (9) through a line; the normal and iso-hexane fractionation column (9) is connected with a normal and iso-hexane fractionation column condenser (11), a normal and iso-hexane fractionation column reflux tank (12), a normal and iso-hexane fractionation column reflux pump (13), a return overhead line and a partial product discharge line in sequence through lines at the top of the column; the normal and iso-hexane fractionation column (9) is connected with a normal and iso-hexane fractionation column reboiler (10) through a line at the bottom of the column.
2. The n-hexane separation and purification device according to claim 1, characterized in that, The benzene-stripping column bottom rich benzene solvent oil is sent to an upstream extraction device extraction distillation column for continuing use as a solvent.
3. The n-hexane separation and purification device according to claim 1, characterized in that, The benzene-stripping column (1) comprises a lean solvent oil feed line, a benzene-containing raffinate oil non-aromatic feed line from an upstream aromatic extraction device, and a benzene solvent oil rich discharge line.
4. The apparatus for separating and purifying n-hexane according to claim 1, wherein, The normal and iso-hexane fractionation column (9) is provided with a product discharge line at the bottom of the column.