CN108046974B - System and method for separating benzene, cyclohexane and cyclohexene - Google Patents
System and method for separating benzene, cyclohexane and cyclohexene Download PDFInfo
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- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 title claims abstract description 115
- HGCIXCUEYOPUTN-UHFFFAOYSA-N cyclohexene Chemical compound C1CCC=CC1 HGCIXCUEYOPUTN-UHFFFAOYSA-N 0.000 title claims abstract description 86
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims description 26
- 238000000605 extraction Methods 0.000 claims abstract description 60
- 238000000895 extractive distillation Methods 0.000 claims abstract description 50
- 239000002994 raw material Substances 0.000 claims abstract description 16
- 238000007599 discharging Methods 0.000 claims abstract description 12
- 238000004821 distillation Methods 0.000 claims abstract description 8
- 239000003795 chemical substances by application Substances 0.000 claims description 30
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 15
- 238000010992 reflux Methods 0.000 claims description 15
- 239000007788 liquid Substances 0.000 claims description 14
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 12
- HXJUTPCZVOIRIF-UHFFFAOYSA-N sulfolane Chemical compound O=S1(=O)CCCC1 HXJUTPCZVOIRIF-UHFFFAOYSA-N 0.000 claims description 10
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 7
- YEJRWHAVMIAJKC-UHFFFAOYSA-N 4-Butyrolactone Chemical compound O=C1CCCO1 YEJRWHAVMIAJKC-UHFFFAOYSA-N 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- LCEDQNDDFOCWGG-UHFFFAOYSA-N morpholine-4-carbaldehyde Chemical compound O=CN1CCOCC1 LCEDQNDDFOCWGG-UHFFFAOYSA-N 0.000 claims description 4
- 239000002608 ionic liquid Substances 0.000 claims description 3
- 238000012856 packing Methods 0.000 claims description 3
- BTGRAWJCKBQKAO-UHFFFAOYSA-N adiponitrile Chemical compound N#CCCCCC#N BTGRAWJCKBQKAO-UHFFFAOYSA-N 0.000 claims description 2
- 238000004064 recycling Methods 0.000 claims description 2
- 238000011084 recovery Methods 0.000 description 18
- 238000000926 separation method Methods 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 5
- 239000012046 mixed solvent Substances 0.000 description 4
- 230000036571 hydration Effects 0.000 description 3
- 238000006703 hydration reaction Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- NIQCNGHVCWTJSM-UHFFFAOYSA-N Dimethyl phthalate Chemical group COC(=O)C1=CC=CC=C1C(=O)OC NIQCNGHVCWTJSM-UHFFFAOYSA-N 0.000 description 2
- WNLRTRBMVRJNCN-UHFFFAOYSA-N adipic acid Chemical compound OC(=O)CCCCC(O)=O WNLRTRBMVRJNCN-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical compound O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 235000011037 adipic acid Nutrition 0.000 description 1
- 239000001361 adipic acid Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000012824 chemical production Methods 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- HPXRVTGHNJAIIH-UHFFFAOYSA-N cyclohexanol Chemical compound OC1CCCCC1 HPXRVTGHNJAIIH-UHFFFAOYSA-N 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- FBSAITBEAPNWJG-UHFFFAOYSA-N dimethyl phthalate Natural products CC(=O)OC1=CC=CC=C1OC(C)=O FBSAITBEAPNWJG-UHFFFAOYSA-N 0.000 description 1
- 229960001826 dimethylphthalate Drugs 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
- C07C7/05—Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds
- C07C7/08—Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds by extractive distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
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- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
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- Oil, Petroleum & Natural Gas (AREA)
- Water Supply & Treatment (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a system for separating benzene, cyclohexane and cyclohexene, which comprises a first extraction rectifying tower (1), a second extraction rectifying tower (2) and a rectifying tower (3) which are sequentially connected; the middle part of the first extractive distillation tower (1) is provided with a raw material feeding pipeline (5), the upper part is provided with an extractant feeding pipeline A (41), the top part is provided with a cyclohexane extracting pipeline (8), the bottom part is provided with a tower bottom discharging pipeline A (6), and the first extractive distillation tower leads to the second extractive distillation tower (2) as a feeding pipeline thereof; the upper part of the second extractive distillation tower (2) is provided with an extractant feeding pipeline B (42), the top part is provided with a benzene extraction pipeline (9), the bottom part is provided with a tower bottom discharging pipeline B (7) which leads to the distillation tower (3) as a feeding pipeline thereof; the rectifying tower (3) is provided with a cyclohexene extraction pipeline (10) at the top and an extractant discharge pipeline (4) at the bottom, and the cyclohexene extraction pipeline is divided into two branches serving as an extractant feeding pipeline A (41) and an extractant feeding pipeline B (42).
Description
Technical Field
The invention relates to the technical field of chemical organic separation, in particular to a system and a method for separating benzene, cyclohexane and cyclohexene.
Background
In chemical production units such as cyclohexene preparation by partial hydrogenation of benzene, cyclohexanol preparation by a cyclohexene hydration method, adipic acid preparation by a cyclohexene hydration method, caprolactam preparation by a cyclohexene hydration method and the like, separation of benzene, cyclohexane and cyclohexene is a necessary operation. However, the three substances have close boiling points, and benzene and cyclohexane, benzene and cyclohexene can form azeotrope and are mainly separated by an extractive distillation method at present.
However, the separation process of benzene, cyclohexane and cyclohexene mostly adopts a four-tower process, so that the energy consumption is large, or the extractive distillation tower is designed as a partition tower, but the pipeline design is still complex and the operation is difficult. Patent CN10261726A presents a typical four-column flow and a divided wall column technology, and proposes a new four-column or five-column flow, the main purpose of which is energy saving. But the invention has the disadvantages of complex flow, large occupied area, more pipelines of the equipment and difficult maintenance. Therefore, a system and a method for separating benzene, cyclohexane and cyclohexene are required to be developed, wherein the process is simple, so that the equipment site investment is reduced, and meanwhile, the energy is saved and the emission is reduced.
Disclosure of Invention
In view of the problems in the prior art, the invention aims to provide a system and a method for separating benzene, cyclohexane and cyclohexene, so that benzene, cyclohexane and cyclohexene products with the purity of more than 99.5 wt% can be purified, the process flow is simplified, the investment on equipment and site is reduced, and the energy conservation and emission reduction are realized effectively.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a system for separating benzene, cyclohexane and cyclohexene, which comprises a first extractive distillation column (1), a second extractive distillation column (2) and a distillation column (3) which are connected in sequence; wherein:
the middle part of the first extractive distillation tower (1) is provided with a raw material feeding pipeline (5), the upper part of the first extractive distillation tower is provided with an extractant feeding pipeline A (41), the top part of the first extractive distillation tower is provided with a cyclohexane extraction pipeline (8), the bottom part of the first extractive distillation tower is provided with a tower bottom discharging pipeline A (6), and the first extractive distillation tower is led to the middle part of the second extractive distillation tower (2) to be used as a feeding pipeline of the second extractive distillation tower (2);
the upper part of the second extractive distillation tower (2) is provided with an extractant feeding pipeline B (42), the top part is provided with a benzene extraction pipeline (9), the bottom part is provided with a tower bottom discharging pipeline B (7), and the second extractive distillation tower is led to the middle part of the distillation tower (3) and is used as a feeding pipeline of the distillation tower (3);
the rectifying tower (3) is provided with a cyclohexene extraction pipeline (10) at the top and an extractant discharge pipeline (4) at the bottom, and the cyclohexene extraction pipeline is divided into two branches serving as an extractant feeding pipeline A (41) and an extractant feeding pipeline B (42).
Preferably, the interiors of the first extractive distillation column (1), the second extractive distillation column (2) and the distillation column (3) are filled with high-efficiency regular packing.
In a second aspect, the present invention provides a method for separating benzene, cyclohexane and cyclohexene, wherein the method is performed by using the system according to the first aspect of the present invention, and comprises the following steps:
(1) adding a raw material containing benzene, cyclohexane and cyclohexene into a first extraction and rectification tower (1) through a raw material feeding pipeline (5), simultaneously adding an extracting agent into the upper part of the first extraction and rectification tower (1) through an extracting agent feeding pipeline A (41), carrying out first extraction and rectification, and extracting a product cyclohexane from the tower top through a cyclohexane extraction pipeline (8);
(2) the tower bottom liquid of the first extraction and rectification tower (1) is led to the middle part of the second extraction and rectification tower (2) through a tower bottom liquid discharging pipeline A (6) to be used as the feeding material of the second extraction and rectification tower (2), meanwhile, an extracting agent is led into the upper part of the second extraction and rectification tower (2) through an extracting agent feeding pipeline B (42) to carry out the second extraction and rectification, and the product benzene is extracted from the tower top through a benzene extracting pipeline (9);
(3) the tower bottom liquid of the second extraction and rectification tower (2) is led to the middle part of the rectification tower (3) through a tower bottom liquid discharging pipeline B (7) to be used as the feeding material of the rectification tower (3) for rectification treatment, the product cyclohexene is extracted from a tower top through a cyclohexene extracting pipeline (10), the extractant is extracted from the tower bottom through an extractant discharging pipeline (4), and then two branches are separated to be used as the extractant feeding pipeline A (41) and the extractant feeding pipeline B (42) and respectively flow back to the upper parts of the first extraction and rectification tower (1) and the second extraction and rectification tower (2), so that the recycling of the extractant is realized.
Wherein the extractant comprises a material selected from:
any one of N, N-Dimethylacetamide (DMAC), N-formylmorpholine (NMF), Dimethylformamide (DMF), gamma-butyrolactone, adiponitrile and ionic liquid; and the combination of (a) and (b),
n-methylpyrrolidone (NMP); and the combination of (a) and (b),
sulfolane;
wherein the weight percentage of sulfolane in the extractant is 50 to 90wt%, such as 50 wt%, 57 wt%, 60 wt%, 65 wt%, 68 wt%, 70 wt%, 75 wt%, 78 wt%, 80 wt%, 85 wt%, 88 wt%, or 90 wt%; the weight percentage of the N-methylpyrrolidone is 5 to 45wt%, for example 5wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt% or 45 wt%.
Preferably, the mass ratio of the extracting agent to the raw material added into the first extractive distillation tower is (1-5): 1, such as 1:1, 1.5:1, 2:1, 2.2:1, 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.8:1, 5: 1; the mass ratio of the extracting agent added into the second extractive distillation tower to the raw material is (1-5) to 1, such as 1:1, 1.5:1, 2:1, 2.2:1, 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.8:1, 5:1 and the like.
Preferably, the pressure of the first extractive distillation column is 1-2 MPa, such as 1MPa, 1.1MPa, 1.2MPa, 1.3MPa, 1.4MPa, 1.5MPa, 1.6MPa, 1.7MPa, 1.8MPa, 1.9MPa or 2MPa, the temperature at the bottom of the column is 140-180 ℃, and the temperature at the top of the column is 80-110 ℃; the pressure of the second extractive distillation tower is 1-2 MPa, such as 1MPa, 1.1MPa, 1.2MPa, 1.3MPa, 1.4MPa, 1.5MPa, 1.6MPa, 1.7MPa, 1.8MPa, 1.9MPa or 2MPa, the tower bottom temperature is 240-280 ℃, and the tower top temperature is 80-110 ℃; the pressure of the rectifying tower is 1-2 MPa, the temperature of the bottom of the rectifying tower is 240-280 ℃, and the temperature of the top of the rectifying tower is 80-110 ℃.
Preferably, the reflux ratio of the first extractive distillation column is 0.1 to 2, such as 0.1, 0.5, 0.7, 1, 1.2, 1.5, 1.7, or 2, preferably 0.5 to 1.5; the reflux ratio of the second extractive distillation tower is 1-10, such as 1, 1.5, 2, 2.6, 3, 4, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.7, 9, 9.6 or 10, preferably 2-6; the reflux ratio of the rectifying tower is 1-10, such as 1, 1.5, 2, 2.6, 3, 4, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.7, 9, 9.6 or 10, preferably 4-8.
Compared with the prior art, the invention has at least the following beneficial effects:
1. the system provided by the invention can purify cyclohexane, benzene and cyclohexene products with the purity of more than 99.5 wt% at one time, and the recovery rate is more than 99%;
2. the extractant has good extraction effect, simple preparation, high solvent recovery rate and low regeneration energy consumption;
3. the invention effectively simplifies the four-tower and five-tower process of separating cyclohexane, cyclohexene and benzene into three-tower process, saves energy, reduces consumption and saves space and equipment investment.
4. The invention changes the traditional separation sequence, directly and sequentially separates cyclohexane, benzene and cyclohexene by one-time utilization of three towers, and overcomes the prejudice that the mixed solvent in the prior art makes the benzene easy to separate from the mixture of cyclohexane and cyclohexene, so that the separation difficulty of cyclohexane and cyclohexene is increased.
5. The method adopts the same mixed extracting agent, achieves the aim of separating different substances by adjusting the solvent ratio of different towers, and has simple operation and outstanding effect.
Drawings
FIG. 1 is a flow chart of a system for separating benzene, cyclohexane and cyclohexene.
The reference numerals in the figures have the following meanings:
1-a first extractive distillation column; 2-a second extractive distillation column; 3-a rectifying tower; 4-extractant discharge line; 41-extractant feed line a; 42-extractant feed line B; 5-a feedstock feed line; 6-tower bottom liquid discharge pipeline A; 7-tower bottom liquid discharge pipeline B; an 8-cyclohexane production line; a 9-benzene production line; 10-cyclohexene extraction line.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
Example 1
A system for separating benzene, cyclohexane and cyclohexene is shown in figure 1 and comprises a first extraction rectifying tower, a second extraction rectifying tower and a rectifying tower which are sequentially connected, wherein the upper parts of the first extraction rectifying tower and the second extraction rectifying tower are respectively provided with an extracting agent feeding pipeline, the bottom of the rectifying tower is provided with an extracting agent recovery pipeline which is connected with extracting agent inlet pipelines of the two towers, and efficient structured packing is filled in the first extraction rectifying tower, the second extraction rectifying tower and the rectifying tower.
The system is used for separating benzene, cyclohexane and cyclohexene from a certain 10 ten thousand ton/year cyclohexanone production device, and comprises the following steps:
(1) adding a raw material containing benzene, cyclohexane and cyclohexene into a first extraction rectifying tower, simultaneously adding an extracting agent into the first extraction rectifying tower through an extracting agent feeding pipeline A, and carrying out first extraction rectification, wherein the pressure in the tower is 1.4MPa, the temperature at the bottom of the tower is 160 ℃, and the temperature at the top of the tower is 90 ℃; the reflux ratio is 0.5; the extracting agent comprises a mixed solvent compounded by N, N-Dimethylacetamide (DMAC), N-methylpyrrolidone (NMP) and sulfolane, wherein the proportion of the sulfolane in the extracting agent is 60 wt%, and the proportion of the NMP in the extracting agent is 30 wt%; the mass ratio of the added extractant to the raw material is 3:1, the product cyclohexane is extracted from the top of the tower, the purity is 99.6 wt%, and the recovery rate is 99.02%;
(2) tower bottom liquid of the first extraction rectifying tower enters the middle part of a second extraction rectifying tower through a tower bottom liquid discharging pipeline A to be subjected to second rectification extraction, and meanwhile, an extracting agent is added into the second extraction rectifying tower through an extracting agent feeding pipeline B, wherein the pressure in the second extraction rectifying tower is 1.4MPa, the temperature at the bottom of the tower is 260 ℃, the temperature at the top of the tower is 90 ℃, and the reflux ratio is 2; the mass ratio of the added extractant to the raw material is 4:1, the product benzene is extracted from the tower top, the purity is 99.7 wt%, and the recovery rate is 99.17%;
(3) the tower bottom liquid of the second extraction and rectification tower enters a rectification tower through a tower bottom liquid discharge pipeline B for separation, the pressure of the rectification tower is 1.5MPa, the temperature at the bottom of the rectification tower is 267 ℃, the temperature at the top of the rectification tower is 85 ℃, and the reflux ratio is 4; the mass ratio of the extracting agent to the raw materials is 1:1, the product cyclohexene is extracted from the tower top, the purity is 99.8 wt%, the recovery rate is 99.15%, and the extracting agent is extracted from the tower bottom and respectively flows back to the first extraction rectifying tower and the second extraction rectifying tower.
Example 2
The system is the same as in example 1, the process is similar, except that:
the composition of the extractant is as follows: the extracting agent is a mixed solvent formed by compounding gamma-butyrolactone, N-methyl pyrrolidone (NMP) and sulfolane, wherein the proportion of the sulfolane in the extracting agent is 90wt%, and the proportion of the NMP is 5 wt%; the reflux ratio of the first extraction rectifying tower is 1.5, the product cyclohexane is extracted from the tower top, the purity is 99.7 wt%, and the recovery rate is 99.13%;
the reflux ratio of the second extractive distillation tower is 6, the purity of the product benzene extracted from the top of the tower is 99.6w percent, and the recovery rate is 99.25 percent; the reflux ratio of the rectifying tower is 8, the purity of the cyclohexene product extracted from the tower top is 99.8 wt%, and the recovery rate is 99.31%.
Example 3
The system is the same as in example 1, the process is similar, except that:
the composition of the extractant is as follows: the ionic liquid, N-methyl pyrrolidone (NMP) and sulfolane are compounded to form a mixed solvent, wherein the specific gravity of the sulfolane in the extracting agent is 80 wt%, and the specific gravity of the NMP in the extracting agent is 10 wt%; the reflux ratio of the first extraction rectifying tower is 1.1, the product cyclohexane is extracted from the tower top, the purity is 99.8 wt%, and the recovery rate is 99.24%;
the reflux ratio of the second extractive distillation tower is 4, the purity of the product benzene extracted from the top of the tower is 99.7w percent, and the recovery rate is 99.25 percent; the reflux ratio of the rectifying tower is 6, the purity of the cyclohexene product extracted from the tower top is 99.7 wt%, and the recovery rate is 99.37%.
Comparative example 1
The only difference from example 1 is: the extractant was replaced with dimethyl phthalate.
The purity of the cyclohexane product extracted from the top of the first extractive distillation tower is 63 wt%, and the recovery rate is 71%;
the purity of the benzene product extracted from the top of the second extractive distillation tower is 67 wt%, and the recovery rate is 53%;
the purity of the cyclohexene product extracted from the top of the rectifying tower is 64 wt%, and the recovery rate is 68%.
Comparative example 2
The only difference from example 1 is: the extractant was replaced with DMAC.
The purity of the cyclohexane product extracted from the top of the first extractive distillation tower is 83 wt%, and the recovery rate is 77%;
the purity of the benzene product extracted from the top of the second extractive distillation tower is 73 wt%, and the recovery rate is 81%;
the purity of the cyclohexene product extracted from the top of the rectifying tower is 61 wt%, and the recovery rate is 69%.
The present invention is illustrated by the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, i.e. it is not meant to imply that the present invention must rely on the above-mentioned detailed process equipment and process flow to be practiced. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (2)
1. A method for separating benzene, cyclohexane and cyclohexene is characterized by being carried out by using the following system:
the system comprises a first extraction rectifying tower (1), a second extraction rectifying tower (2) and a rectifying tower (3) which are connected in sequence; wherein:
the middle part of the first extractive distillation tower (1) is provided with a raw material feeding pipeline (5), the upper part of the first extractive distillation tower is provided with an extractant feeding pipeline A (41), the top part of the first extractive distillation tower is provided with a cyclohexane extraction pipeline (8), the bottom part of the first extractive distillation tower is provided with a tower bottom discharging pipeline A (6), and the first extractive distillation tower is led to the middle part of the second extractive distillation tower (2) to be used as a feeding pipeline of the second extractive distillation tower (2);
the upper part of the second extractive distillation tower (2) is provided with an extractant feeding pipeline B (42), the top part is provided with a benzene extraction pipeline (9), the bottom part is provided with a tower bottom discharging pipeline B (7), and the second extractive distillation tower is led to the middle part of the distillation tower (3) and is used as a feeding pipeline of the distillation tower (3);
the top of the rectifying tower (3) is provided with a cyclohexene extraction pipeline (10), the bottom of the rectifying tower is provided with an extractant discharging pipeline (4) which is divided into two branches as an extractant feeding pipeline A (41) and an extractant feeding pipeline B (42);
efficient structured packing is filled in the first extractive distillation tower (1), the second extractive distillation tower (2) and the distillation tower (3);
the method comprises the following steps:
(1) adding a raw material containing benzene, cyclohexane and cyclohexene into a first extraction and rectification tower (1) through a raw material feeding pipeline (5), simultaneously adding an extracting agent into the upper part of the first extraction and rectification tower (1) through an extracting agent feeding pipeline A (41), carrying out first extraction and rectification, and extracting a product cyclohexane from the tower top through a cyclohexane extraction pipeline (8);
(2) the tower bottom liquid of the first extraction and rectification tower (1) is led to the middle part of the second extraction and rectification tower (2) through a tower bottom liquid discharging pipeline A (6) to be used as the feeding material of the second extraction and rectification tower (2), meanwhile, an extracting agent is led into the upper part of the second extraction and rectification tower (2) through an extracting agent feeding pipeline B (42) to carry out the second extraction and rectification, and the product benzene is extracted from the tower top through a benzene extracting pipeline (9);
(3) the tower bottom liquid of the second extraction and rectification tower (2) is introduced to the middle part of the rectification tower (3) through a tower bottom liquid discharge pipeline B (7) to be used as the feed of the rectification tower (3) for rectification treatment, a product cyclohexene is extracted from the tower top through a cyclohexene extraction pipeline (10), an extractant is extracted from the tower bottom through an extractant discharge pipeline (4), and then two branches are separated to be used as an extractant feed pipeline A (41) and an extractant feed pipeline B (42) and respectively flow back to the upper parts of the first extraction and rectification tower (1) and the second extraction and rectification tower (2), so that the recycling of the extractant is realized;
the extractant comprises a material selected from:
any one of N, N-Dimethylacetamide (DMAC), N-formylmorpholine (NMF), Dimethylformamide (DMF), gamma-butyrolactone, adiponitrile and ionic liquid; and the combination of (a) and (b),
n-methylpyrrolidone (NMP); and the combination of (a) and (b),
sulfolane;
wherein the weight percentage of sulfolane in the extracting agent is 50-90 wt%, and the weight percentage of N-methyl pyrrolidone is 5-45 wt%;
the mass ratio of the extracting agent added into the first extractive distillation tower to the raw material is (1-5) to 1; the mass ratio of the extracting agent added into the second extractive distillation tower to the raw material is (1-5) to 1;
the reflux ratio of the first extractive distillation tower is 0.5-1.5; the reflux ratio of the second extractive distillation tower is 2-6; the reflux ratio of the rectifying tower is 4-8.
2. The method for separating benzene, cyclohexane and cyclohexene according to claim 1, wherein the pressure of the first extractive distillation tower is 1-2 MPa, the temperature of the bottom of the tower is 140-180 ℃, and the temperature of the top of the tower is 80-110 ℃; the pressure of the second extractive distillation tower is 1-2 MPa, the temperature of the tower bottom is 240-280 ℃, and the temperature of the tower top is 80-110 ℃; the pressure of the rectifying tower is 1-2 MPa, the temperature of the bottom of the rectifying tower is 240-280 ℃, and the temperature of the top of the rectifying tower is 80-110 ℃.
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| CN201711480168.7A CN108046974B (en) | 2017-12-29 | 2017-12-29 | System and method for separating benzene, cyclohexane and cyclohexene |
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| CN112661593B (en) * | 2021-02-05 | 2023-07-18 | 郑州轻工业大学 | Method for separating benzene, cyclohexene and cyclohexane by extracting and rectifying mixed solvent containing ionic liquid |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS51127043A (en) * | 1975-04-24 | 1976-11-05 | Toray Ind Inc | Process for purification of cyclohexene |
| JPH01135730A (en) * | 1987-11-24 | 1989-05-29 | Asahi Chem Ind Co Ltd | Method for separating cyclohexene by mixed solvent |
| CN102134177A (en) * | 2011-02-28 | 2011-07-27 | 河北民海化工有限公司 | Method for separating cyclohexane and cyclohexene by extraction and rectification |
| CN102690161A (en) * | 2012-05-31 | 2012-09-26 | 中国天辰工程有限公司 | Separating method for benzene-cyclohexane-cyclohexene |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS58172323A (en) * | 1982-04-02 | 1983-10-11 | Asahi Chem Ind Co Ltd | Separation of monocyclic monoolefin |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS51127043A (en) * | 1975-04-24 | 1976-11-05 | Toray Ind Inc | Process for purification of cyclohexene |
| JPH01135730A (en) * | 1987-11-24 | 1989-05-29 | Asahi Chem Ind Co Ltd | Method for separating cyclohexene by mixed solvent |
| CN102134177A (en) * | 2011-02-28 | 2011-07-27 | 河北民海化工有限公司 | Method for separating cyclohexane and cyclohexene by extraction and rectification |
| CN102690161A (en) * | 2012-05-31 | 2012-09-26 | 中国天辰工程有限公司 | Separating method for benzene-cyclohexane-cyclohexene |
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