Device for separating ethanol-normal hexane-cyclohexane multi-element azeotrope

Abstract

The utility model discloses a device for separating ethanol-n-hexane-cyclohexane multi-element azeotrope, which comprises an extractive distillation partition plate tower, the extractive distillation partition plate tower is divided into a main tower and an auxiliary tower through a partition plate, and the main tower is connected with a multi-element azeotrope feeding pipeline, an extracting agent feeding pipeline and a reboiler I; the top of the main tower is connected with a condenser I and a reflux tank I, and the reflux tank I is connected with a cyclohexane extraction pipeline; the top of the auxiliary tower is connected with a condenser II and a reflux tank II; the reflux tank II is connected with an n-hexane extraction pipeline; the bottom of the extractive distillation partition plate tower is connected with a solvent recovery tower through an ethanol-extractant extraction pipeline, the solvent recovery tower is connected with a reboiler II, the top of the solvent recovery tower is connected with a condenser III and a reflux tank III, the reflux tank III is connected with an ethanol extraction pipeline, and the bottom of the solvent recovery tower is connected with an extractant extraction pipeline. According to the utility model, a rectifying tower device and a reboiler are saved, and the thermal load of the reboiler is reduced on the basis of improving the thermodynamic efficiency in the tower, so that the aim of saving energy is fulfilled.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical separation, in particular to a device for separating ethanol-normal hexane-cyclohexane multi-element azeotropic products. Background Art

[0002] Ethanol is a common solvent and organic raw material in chemical enterprises. Ethanol can be used to make acetic acid, beverages, flavors, dyes, fuels, etc. In medicine, ethanol with a volume fraction of 70-75% is also commonly used as a disinfectant, etc. It has a wide range of uses in national defense chemical industry, medical and health, food industry, and industrial and agricultural production. N-hexane is mainly used as a solvent, such as vegetable oil extraction solvent, propylene polymerization solvent, rubber and coating solvent, pigment diluent, and is also used for the extraction of various edible oils and fats such as soybeans, rice bran, cottonseed, and spices. In addition, n-hexane isomerization is one of the important processes for producing high-octane gasoline blending components. Cyclohexane is used as a general solvent, chromatographic analysis standard substance, and for organic synthesis. It can be used in resins, coatings, fats, paraffin oils, and can also prepare organic substances such as cyclohexanol and cyclohexanone. In industry, ethanol and propionic acid are often used as raw materials to synthesize ethyl propionate, with n-hexane and cyclohexane as water carriers. In view of the uses of ethanol, n-hexane, and cyclohexane, it is particularly important to separate and recover ethanol, n-hexane, and cyclohexane.

[0003] However, ethanol and n-hexane / cyclohexane can form binary azeotropic mixtures under normal pressure, which are difficult to separate by ordinary distillation. The common method for this binary azeotrope is extractive distillation, but the disadvantage of conventional extractive distillation is that the energy consumption is too high, which increases the operating cost of the distillation tower and violates the new concept of energy conservation and emission reduction in industry. Utility Model Content

[0004] The technical problem to be solved by the utility model is: to overcome the deficiencies of the prior art and provide a device for separating ethanol-n-hexane-cyclohexane multi-element azeotrope, by embedding a partition in the extractive distillation partition tower to divide it into a main tower and a sub-tower, thereby saving a distillation tower equipment and a reboiler, and at the same time reducing the heat load of the reboiler on the basis of improving the thermodynamic efficiency in the tower, thereby achieving the purpose of energy saving.

[0005] The technical solution of the utility model is:

[0006] On the one hand, the utility model provides a device for separating ethanol-n-hexane-cyclohexane multi-element azeotropes, comprising an extractive distillation baffle tower, wherein a baffle is vertically arranged in the extractive distillation baffle tower, and the extractive distillation baffle tower is divided into a main tower and a sub-tower, wherein the main tower is connected with a multi-element azeotrope feed pipeline, an extractant feed pipeline and a reboiler 1; the top of the main tower is connected with a condenser 1 through a pipeline, the condenser 1 is connected with a reflux tank 1 through a pipeline, the reflux tank 1 is connected with a reflux pipeline 1 and a cyclohexane extraction pipeline, and the reflux pipeline 1 is connected to the reflux port of the main tower; the top of the sub-tower is connected with a condenser 2 through a pipeline, and the condenser 2 is connected with a reflux tank 1 through a pipeline. The second condenser is connected to the second reflux tank through a pipeline, the second reflux tank is connected to the second reflux pipeline and the n-hexane extraction pipeline, and the second reflux pipeline is connected to the reflux port of the auxiliary tower; the bottom of the extractive distillation partition tower is connected to the feed port of the solvent recovery tower through the ethanol-extractant extraction pipeline, the solvent recovery tower is connected to the second reboiler, the top of the solvent recovery tower is connected to the third condenser through a pipeline, the third condenser is connected to the third reflux tank through a pipeline, the third reflux tank is connected to the third reflux pipeline and the ethanol extraction pipeline, the third reflux pipeline is connected to the reflux port of the solvent recovery tower, and the bottom of the solvent recovery tower is connected to the extractant extraction pipeline.

[0007] Preferably, the extractant withdrawal pipeline is connected to the extractant feed pipeline of the main tower.

[0008] Preferably, a condenser 4 is connected to the extractant production pipeline.

[0009] Preferably, the number of plates of the main tower is 45-55, and the number of plates of the auxiliary tower is 22-30.

[0010] Preferably, the multi-element azeotrope feed line is connected to the 28th to 35th tray of the main tower, and the extractant feed line is connected to the 4th to 10th tray of the main tower.

[0011] Preferably, the number of plates of the solvent recovery tower is 15-25, and the ethanol-extractant extraction pipeline is connected to the 10-18 plate of the solvent recovery tower.

[0012] Preferably, the extractant in the extractant feeding pipeline is butyl butyrate.

[0013] On the other hand, the utility model also provides a method for separating ethanol-n-hexane-cyclohexane multi-element azeotrope using the above device, comprising the following steps:

[0014] S1 ethanol-n-hexane-cyclohexane multi-element azeotrope is fed from the middle and lower part of the main tower of the extractive distillation baffle tower, and the extractant is fed from the upper part of the main tower. The material at the top of the main tower is condensed in the condenser and stored in the reflux tank. A part of it is extracted as the cyclohexane product, and the other part is refluxed to the main tower;

[0015] The material produced from the lower part of the S2 main tower enters the auxiliary tower. After the material at the top of the tower is condensed by the second condenser and stored in the second reflux tank, part of it is produced as the n-hexane product, and the other part is refluxed to the auxiliary tower;

[0016] The ethanol-extractant mixture produced from the bottom of the S3 main tower enters the lower middle part of the solvent recovery tower. After the materials at the top of the solvent recovery tower are condensed in the condenser three and stored in the reflux tank three, part of them are produced as ethanol products, and the other part is refluxed to the solvent recovery tower;

[0017] The bottom of the S4 solvent recovery tower is a high-purity extractant, which is condensed in condenser 4 and then recycled;

[0018] During the operation of S5, part of the extractant will be lost, so a small amount of extractant needs to be added.

[0019] Preferably, the pressure of the main tower, the auxiliary tower and the solvent recovery tower is 0.6-2.2 atm, and the reflux ratio is 0.85-7.5.

[0020] Preferably, the top temperature of the main tower is 78-85°C, and the bottom temperature is 140-148°C; the top temperature of the auxiliary tower is 68-82°C, and the bottom temperature is 130-145°C; the top temperature of the solvent recovery tower is 72-80°C, and the bottom temperature is 165-173°C.

[0021] Compared with the prior art, the utility model has the following beneficial effects:

[0022] The utility model adopts butyl butyrate as an extractant to separate an ethanol-n-hexane-cyclohexane azeotropic system. On the basis of a conventional separation sequence, a partition is built into an extractive distillation partition tower to divide it into a main tower and a sub-tower, thereby saving a distillation tower equipment and a reboiler, and at the same time, on the basis of improving the thermodynamic efficiency in the tower, the heat load of the reboiler is reduced, thereby achieving the purpose of energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The utility model is a schematic diagram of the structure of a device for separating ethanol-n-hexane-cyclohexane multi-element azeotrope.

[0024] Figure 2 It is a schematic diagram of the structure of a conventional device for separating ethanol-n-hexane-cyclohexane multi-phase azeotrope by extractive distillation.

[0025] In the figure, 1, extractive distillation baffle tower; 101, baffle; 102, main tower; 1021, condenser 1; 1022, reflux tank 1; 1023, reflux pipeline 1; 103, auxiliary tower; 1031, condenser 2; 1032, reflux tank 2; 1033, reflux pipeline 2; 104, reboiler 1; 2, multi-element azeotrope feed pipeline; 3, extractant feed pipeline; 4, cyclohexane production pipeline; 5, n-hexane production pipeline; 6, ethanol-extractant production pipeline; 7, solvent recovery tower; 701, reboiler 2; 702, condenser 3; 703, reflux tank 3; 704, reflux pipeline 3; 8 , ethanol production pipeline; 9, extractant production pipeline; 901, condenser four; 10, extractive distillation tower one; 1001, extractant feed pipeline one; 1002, reboiler three; 1003, condenser five; 1004, reflux tank four; 1005, reflux pipeline four; 11, extractive distillation tower two; 1101, extractant feed pipeline two; 1102, reboiler four; 1103, condenser six; 1104, reflux tank five; 1105, reflux pipeline five; 1201, reboiler five; 1202, condenser seven; 1203, reflux tank six; 1204, reflux pipeline six; 13, condenser eight. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0027] like Figure 1As shown, the device for separating ethanol-n-hexane-cyclohexane multi-electrode in the following embodiment comprises an extractive distillation baffle tower 1, in which a baffle 101 is vertically arranged, and the extractive distillation baffle tower 1 is divided into a main tower 102 and a sub-tower 103, the main tower 102 is connected with a multi-electrode feed pipeline 2, an extractant feed pipeline 3 and a reboiler 104, and the extractant in the extractant feed pipeline 3 adopts butyl butyrate extractant; the top of the main tower 102 is connected with a condenser 1021 through a pipeline, the condenser 1021 is connected with a reflux tank 1022 through a pipeline, the reflux tank 1022 is connected with a reflux pipeline 1023 and a cyclohexane extraction pipeline 4, and the reflux pipeline 1023 is connected to the reflux port of the main tower 102; the top of the sub-tower 103 is connected with a condenser 1031 through a pipeline, and the condenser 1031 is connected with a reflux port 1023 through a pipeline. It is connected to a reflux tank 1032, which is connected to a reflux pipeline 1033 and a n-hexane extraction pipeline 5, and the reflux pipeline 1033 is connected to the reflux port of the auxiliary tower 103; the bottom of the extractive distillation partition tower 1 is connected to the feed port of the solvent recovery tower 7 through the ethanol-extractant extraction pipeline 6, the solvent recovery tower 7 is connected to a reboiler 701, the top of the solvent recovery tower 7 is connected to a condenser 702 through a pipeline, the condenser 702 is connected to a reflux tank 3 703 through a pipeline, the reflux tank 3 703 is connected to a reflux pipeline 3 704 and an ethanol extraction pipeline 8, the reflux pipeline 3 704 is connected to the reflux port of the solvent recovery tower 7, the bottom of the solvent recovery tower 7 is connected to an extractant extraction pipeline 9, the extractant extraction pipeline 9 is connected to the extractant feed pipeline 3 of the main tower 102, and the extractant extraction pipeline 9 is connected to a condenser 901.

[0028] Among them, the number of plates of the main tower 102 is 45-55, the number of plates of the sub-tower 103 is 22-30, the multi-electrode feed pipeline 2 is connected to the 28-35 plates of the main tower 102, and the extractant feed pipeline 3 is connected to the 4-10 plates of the main tower 102; the number of plates of the solvent recovery tower 7 is 15-25, and the ethanol-extractant production pipeline 6 is connected to the 10-18 plates of the solvent recovery tower 7.

[0029] like Figure 2As shown, the following comparative example adopts a conventional extractive distillation device for separating ethanol-n-hexane-cyclohexane multi-phase azeotrope, including an extractive distillation tower 10, the extractive distillation tower 10 is connected to a multi-phase azeotrope feed pipeline 2, an extractant feed pipeline 1001 and a reboiler 3 1002, the top of the extractive distillation tower 10 is connected to a condenser 5 1003 through a pipeline, the condenser 5 1003 is connected to a reflux tank 4 1004 through a pipeline, and the reflux tank 4 1004 is connected to a reflux pipeline four 1005 and a cyclohexane extraction pipeline 4, and the reflux pipeline four 1005 is connected to the reflux port of the extractive distillation tower one 10; the bottom of the extractive distillation tower one 10 is connected to the extractive distillation tower two 11 through a discharge pipeline, the extractive distillation tower two 11 is connected to the extractant feed pipeline two 1101 and the reboiler four 1102, and the top of the extractive distillation tower two 11 is connected to the condenser six 1103 through a pipeline, and the condenser six 1103 is connected to the extractive distillation tower two 1103 through a discharge pipeline. The pipeline is connected to a reflux tank 5 1104, the reflux tank 5 1104 is connected to a reflux pipeline 5 1105 and a n-hexane extraction pipeline 5, and the reflux pipeline 5 1105 is connected to the reflux port of the extractive distillation tower 2 11; the bottom of the extractive distillation tower 2 11 is connected to the feed port of the solvent recovery tower 7 through a discharge pipeline, the solvent recovery tower 7 is connected to a reboiler 5 1201, and the top of the solvent recovery tower 7 is connected to a condenser 7 1202 through a pipeline, and the condenser 7 1 202 is connected to a reflux tank six 1203 through a pipeline, the reflux tank six 1203 is connected to a reflux pipeline six 1204 and an ethanol production pipeline 8, the reflux pipeline six 1204 is connected to the reflux port of a solvent recovery tower 7, the bottom of the solvent recovery tower 7 is connected to an extractant production pipeline 9, the extractant production pipeline 9 is connected to an extractant feed pipeline one 1001 and an extractant feed pipeline two 1101, and the extractant production pipeline 9 is connected to a condenser eight 13.

[0030] Example 1

[0031] In the device for separating ethanol-n-hexane-cyclohexane multi-element azeotrope of the present embodiment, the main tower 102 of the extractive distillation baffle tower 1 has 50 tower plates, the auxiliary tower 103 has 25 tower plates, and the solvent recovery tower 7 has 20 tower plates. The process of separating ethanol-n-hexane-cyclohexane multi-element azeotrope by using the device is as follows:

[0032] S1 is a multi-electrode azeotrope of ethanol-n-hexane-cyclohexane (molar ratio of 0.3:0.3:0.4) with a flow rate of 100 kmol / h, which is fed to the 32nd plate of the main tower 102, and an extractant with a flow rate of 180 kmol / h is fed to the 6th plate of the main tower 102. The operation is carried out at a pressure of 1 atm, a reflux ratio of 2.5, a top temperature of 80.7°C, and a bottom temperature of 145°C. After the material at the top of the tower is condensed in a condenser 1021 and stored in a reflux tank 1022, a part of it is produced as a cyclohexane product, and the other part is refluxed to the main tower 102, wherein the molar fraction of the cyclohexane product is greater than 0.999%.

[0033] The material produced from the lower part of the S2 main tower 102 enters the auxiliary tower 103, which is operated at a pressure of 1 atm, with a reflux ratio of 2.5, a top temperature of 70°C, and a bottom temperature of 135°C; after the material at the top of the auxiliary tower 103 is condensed by the condenser 1031 and stored in the reflux tank 1032, a part of it is produced as the n-hexane product, and the other part is refluxed to the auxiliary tower 103, and the molar fraction of the n-hexane product is greater than 0.999%.

[0034] The bottom of the S3 extractive distillation baffle tower 1 is an ethanol-extractant mixture, which is extracted to the solvent recovery tower 7 through the ethanol-extractant extraction pipeline 6 and fed from the 15th tower plate. It is operated at a pressure of 1 atm, with a reflux ratio of 1.8, a top temperature of 75°C, and a bottom temperature of 167°C. After the material at the top of the tower is condensed by the condenser three 702 and stored in the reflux tank three 703, a part of it is extracted as an ethanol product, and the other part is refluxed to the solvent recovery tower 7, and the molar fraction of the ethanol product is greater than 0.999%.

[0035] The bottom of the S4 solvent recovery tower 7 is an extractant with a molar fraction greater than 0.9999%, which is condensed in the condenser 901 and then returned to the main tower 102 of the extractive distillation partition tower 1 for recycling.

[0036] Some of the extractant will be lost during the operation of S5, so a small amount of extractant needs to be added during the process.

[0037] Comparative Example 1

[0038] In the device for separating ethanol-n-hexane-cyclohexane multi-element azeotrope of Comparative Example 1, the extractive distillation tower 10 has 50 plates, the extractive distillation tower 2 11 has 45 plates, and the solvent recovery tower 7 has 20 plates. The process of separating ethanol-n-hexane-cyclohexane multi-element azeotrope using the device is as follows:

[0039] S1 is a multi-electrode of ethanol-n-hexane-cyclohexane (molar ratio of 0.3:0.3:0.4) with a flow rate of 100 kmol / h. It is fed to the 32nd plate of the extractive distillation tower-10, and the extractant with a flow rate of 180 kmol / h is fed to the 6th plate of the extractive distillation tower-10. The operation is carried out at a pressure of 1 atm, with a reflux ratio of 2.5, a top temperature of 80.7°C, and a bottom temperature of 145°C. After the material at the top of the tower is condensed by the condenser five 1003 and stored in the reflux tank four 1004, a part of it is produced as a cyclohexane product, and the other part is refluxed to the extractive distillation tower-10, wherein the molar fraction of the cyclohexane product is greater than 0.999%.

[0040] The bottom material of S2 extractive distillation tower 10 enters extractive distillation tower 2 11 from the 32nd tower plate, and the extractant with a flow rate of 130 kmol / h is fed to the 6th tower plate of extractive distillation tower 2 11. It is operated at a pressure of 1 atm, with a reflux ratio of 2.5, a top temperature of 70°C, and a bottom temperature of 135°C. After the material at the top of the tower is condensed by condenser 6 1103 and stored in reflux tank 5 1104, a part of it is produced as n-hexane product, and the other part is refluxed to the extractive distillation tower 2 11, and the molar fraction of the n-hexane product is greater than 0.999%.

[0041] The bottom material of the S3 extractive distillation tower 2 11 enters from the 15th tower plate of the solvent recovery tower 7 and is operated at a pressure of 1 atm, with a reflux ratio of 1.8, a top temperature of 75°C, and a bottom temperature of 167°C. After the top material is condensed by the condenser 7 1202 and stored in the reflux tank 6 1203, a part of it is extracted as an ethanol product and the other part is refluxed to the solvent recovery tower 7, and the molar fraction of the ethanol product is greater than 0.999%.

[0042] The bottom of S4 solvent recovery tower 7 is an extractant with a molar fraction greater than 0.9999%, which is condensed by condenser eight 13 and then returned to extractive distillation tower one 10 and extractive distillation tower two 11 for recycling as an extractant.

[0043] Some of the extractant will be lost during the operation of S5, so a small amount of extractant needs to be added during the process.

[0044] When the ethanol-n-hexane-cyclohexane multi-element azeotrope is separated using the apparatus of Example 1 and Comparative Example 1, the energy consumption comparison is shown in Table 1:

[0045] Table 1 Comparison of energy consumption when separating ethanol-n-hexane-cyclohexane multi-element azeotrope between Example 1 and Comparative Example 1

[0046]

[0047] Example 2

[0048] In the device for separating ethanol-n-hexane-cyclohexane multi-element azeotrope of the present embodiment, the main tower 102 of the extractive distillation baffle tower 1 has 46 tower plates, the auxiliary tower 103 has 23 tower plates, and the solvent recovery tower 7 has 18 tower plates. The process of separating ethanol-n-hexane-cyclohexane multi-element azeotrope by using the device is as follows:

[0049] S1 is a multi-electrode azeotrope of ethanol-n-hexane-cyclohexane (molar ratio of 0.4:0.3:0.3) with a flow rate of 100 kmol / h. It is fed to the 30th plate of the main tower 102, and the extractant with a flow rate of 190 kmol / h is fed to the 8th plate of the main tower 102. The operation is carried out at a pressure of 1 atm, a reflux ratio of 2, a top temperature of 78°C, and a bottom temperature of 140°C. After the material at the top of the tower is condensed in a condenser 1021 and stored in a reflux tank 1022, a part of it is produced as a cyclohexane product, and the other part is refluxed to the main tower 102, wherein the molar fraction of the cyclohexane product is greater than 0.999%.

[0050] The material produced from the lower part of the S2 main tower 102 enters the auxiliary tower 103, which is operated at a pressure of 1 atm, with a reflux ratio of 2.3, a top temperature of 68°C, and a bottom temperature of 130°C; after the material at the top of the auxiliary tower 103 is condensed by the condenser 1031 and stored in the reflux tank 1032, a part of it is produced as the n-hexane product, and the other part is refluxed to the auxiliary tower 103, and the molar fraction of the n-hexane product is greater than 0.999%.

[0051] The bottom of the S3 extractive distillation baffle tower 1 is an ethanol-extractant mixture, which is extracted to the solvent recovery tower 7 through the ethanol-extractant extraction pipeline 6 and fed from the 13th tower plate. It is operated at a pressure of 1atm, with a reflux ratio of 2, a top temperature of 72°C, and a bottom temperature of 165°C. After the material at the top of the tower is condensed by the condenser three 702 and stored in the reflux tank three 703, a part of it is extracted as an ethanol product, and the other part is refluxed to the solvent recovery tower 7, and the molar fraction of the ethanol product is greater than 0.999%.

[0052] The bottom of the S4 solvent recovery tower 7 is an extractant with a molar fraction greater than 0.9999%, which is condensed in the condenser 901 and then returned to the main tower 102 of the extractive distillation partition tower 1 for recycling.

[0053] Some of the extractant will be lost during the operation of S5, so a small amount of extractant needs to be added during the process.

[0054] Comparative Example 2

[0055] In the device for separating ethanol-n-hexane-cyclohexane multi-element azeotrope of Comparative Example 2, the extractive distillation tower 10 has 46 plates, the extractive distillation tower 2 11 has 47 plates, and the solvent recovery tower 7 has 18 plates. The process of separating ethanol-n-hexane-cyclohexane multi-element azeotrope using the device is as follows:

[0056] S1 is a polyazeotropic mixture of ethanol, normal hexane and cyclohexane (molar ratio of 0.4:0.3:0.3) with a flow rate of 100 kmol / h. It is fed to the 30th plate of the extractive distillation tower 10, and the extractant with a flow rate of 190 kmol / h is fed to the 8th plate of the extractive distillation tower 10. The operation is carried out at a pressure of 1 atm, a reflux ratio of 2, a top temperature of 78°C, and a bottom temperature of 140°C. After the material at the top of the tower is condensed by the condenser five 1003 and stored in the reflux tank four 1004, a part of it is produced as a cyclohexane product, and the other part is refluxed to the extractive distillation tower one 10, wherein the molar fraction of the cyclohexane product is greater than 0.999%.

[0057] The bottom material of S2 extractive distillation tower 10 enters extractive distillation tower 2 11 from the 38th tower plate, and the extractant with a flow rate of 150 kmol / h is fed to the 8th tower plate of extractive distillation tower 2 11. It is operated at a pressure of 1 atm, with a reflux ratio of 2.3, a top temperature of 68°C, and a bottom temperature of 130°C. After the material at the top of the tower is condensed by condenser 6 1103 and stored in reflux tank 5 1104, a part of it is produced as n-hexane product, and the other part is refluxed to the extractive distillation tower 2 11, and the molar fraction of the n-hexane product is greater than 0.999%.

[0058] The bottom material of the S3 extractive distillation tower 2 11 enters from the 13th tower plate of the solvent recovery tower 7, and is operated at a pressure of 1 atm, with a reflux ratio of 2, a tower top temperature of 72°C, and a tower bottom temperature of 165°C; after the top material is condensed by the condenser 7 1202 and stored in the reflux tank 6 1203, a part of it is extracted as an ethanol product, and the other part is refluxed to the solvent recovery tower 7, and the molar fraction of the ethanol product is greater than 0.999%.

[0059] The bottom of S4 solvent recovery tower 7 is an extractant with a molar fraction greater than 0.9999%, which is condensed by condenser eight 13 and then returned to extractive distillation tower one 10 and extractive distillation tower two 11 for recycling as an extractant.

[0060] Some of the extractant will be lost during the operation of S5, so a small amount of extractant needs to be added during the process.

[0061] When the apparatus of Example 2 and Comparative Example 2 are used to separate ethanol-n-hexane-cyclohexane polyhydric azeotrope, the energy consumption comparison is shown in Table 2:

[0062] Table 2 Comparison of energy consumption when separating ethanol-n-hexane-cyclohexane multi-element azeotrope between Example 2 and Comparative Example 2

[0063]

[0064] Example 3

[0065] In the device for separating ethanol-n-hexane-cyclohexane multi-element azeotrope of the present embodiment, the main tower 102 of the extractive distillation baffle tower 1 has 55 plates, the auxiliary tower 103 has 28 plates, and the solvent recovery tower 7 has 22 plates. The process of separating ethanol-n-hexane-cyclohexane multi-element azeotrope by using the device is as follows:

[0066] S1 is a multi-electrode of ethanol-n-hexane-cyclohexane (molar ratio of 0.3:0.4:0.3) with a flow rate of 100 kmol / h. It is fed to the 35th plate of the main tower 102, and the extractant with a flow rate of 150 kmol / h is fed to the 8th plate of the main tower 102. The operation is carried out at a pressure of 1 atm, a reflux ratio of 1.6, a top temperature of 85°C, and a bottom temperature of 148°C. After the material at the top of the tower is condensed in a condenser 1021 and stored in a reflux tank 1022, a part of it is produced as a cyclohexane product, and the other part is refluxed to the main tower 102, wherein the molar fraction of the cyclohexane product is greater than 0.999%.

[0067] The material produced from the lower part of the S2 main tower 102 enters the auxiliary tower 103, which is operated at a pressure of 1 atm, with a reflux ratio of 1.65, a top temperature of 82°C, and a bottom temperature of 145°C; after the material at the top of the auxiliary tower 103 is condensed by the condenser 1031 and stored in the reflux tank 1032, a part of it is produced as the n-hexane product, and the other part is refluxed to the auxiliary tower 103, and the molar fraction of the n-hexane product is greater than 0.999%.

[0068] The bottom of the S3 extractive distillation baffle tower 1 is an ethanol-extractant mixture, which is extracted to the solvent recovery tower 7 through the ethanol-extractant extraction pipeline 6 and fed from the 16th tower plate. It is operated at a pressure of 1atm, with a reflux ratio of 1.83, a top temperature of 80°C, and a bottom temperature of 173°C. After the material at the top of the tower is condensed by the condenser three 702 and stored in the reflux tank three 703, a part of it is extracted as an ethanol product, and the other part is refluxed to the solvent recovery tower 7, and the molar fraction of the ethanol product is greater than 0.999%.

[0069] The bottom of the S4 solvent recovery tower 7 is an extractant with a molar fraction greater than 0.9999%, which is condensed in the condenser 901 and then returned to the main tower 102 of the extractive distillation partition tower 1 for recycling.

[0070] Some of the extractant will be lost during the operation of S5, so a small amount of extractant needs to be added during the process.

[0071] Comparative Example 3

[0072] In the device for separating ethanol-n-hexane-cyclohexane multi-aqueous azeotrope of Comparative Example 3, the extractive distillation tower 10 has 55 plates, the extractive distillation tower 2 11 has 50 plates, and the solvent recovery tower 7 has 22 plates. The process of separating ethanol-n-hexane-cyclohexane multi-aqueous azeotrope using the device is as follows:

[0073] S1 is a multi-electrode azeotrope of ethanol-n-hexane-cyclohexane (molar ratio of 0.3:0.4:0.3) with a flow rate of 100 kmol / h. It is fed to the 37th plate of the extractive distillation tower-10, and the extractant with a flow rate of 150 kmol / h is fed to the 8th plate of the extractive distillation tower-10. The operation is carried out at a pressure of 1 atm, a reflux ratio of 1.6, a top temperature of 85°C, and a bottom temperature of 148°C. After the material at the top of the tower is condensed by the condenser five 1003 and stored in the reflux tank four 1004, a part of it is produced as the cyclohexane product, and the other part is refluxed to the extractive distillation tower-10, wherein the molar fraction of the cyclohexane product is greater than 0.999%.

[0074] The bottom material of S2 extractive distillation tower 10 enters extractive distillation tower 2 11 from the 36th tower plate, and the extractant with a flow rate of 120 kmol / h is fed to the 7th tower plate of extractive distillation tower 2 11. It is operated at a pressure of 1 atm, with a reflux ratio of 1.65, a tower top temperature of 82°C, and a tower bottom temperature of 145°C. After the material at the top of the tower is condensed by condenser 6 1103 and stored in reflux tank 5 1104, a part of it is produced as n-hexane product, and the other part is refluxed to the extractive distillation tower 2 11, and the molar fraction of the n-hexane product is greater than 0.999%.

[0075] The bottom material of the S3 extractive distillation tower 2 11 enters from the 16th tower plate of the solvent recovery tower 7 and operates at a pressure of 1 atm, with a reflux ratio of 1.83, a tower top temperature of 80°C, and a tower bottom temperature of 173°C; after the top material is condensed by the condenser 7 1202 and stored in the reflux tank 6 1203, a part of it is extracted as an ethanol product, and the other part is refluxed to the solvent recovery tower 7, and the molar fraction of the ethanol product is greater than 0.999%.

[0076] The bottom of S4 solvent recovery tower 7 is an extractant with a molar fraction greater than 0.9999%, which is condensed by condenser eight 13 and then returned to extractive distillation tower one 10 and extractive distillation tower two 11 for recycling as an extractant.

[0077] Some of the extractant will be lost during the operation of S5, so a small amount of extractant needs to be added during the process.

[0078] When the apparatus of Example 3 and Comparative Example 3 are used to separate ethanol-n-hexane-cyclohexane polyhydric azeotrope, the energy consumption comparison is shown in Table 3:

[0079] Table 3 Comparison of energy consumption when separating ethanol-n-hexane-cyclohexane multi-element azeotrope between Example 3 and Comparative Example 3

[0080]

[0081] By comparing Examples 1-3 with Comparative Examples 1-3, it can be seen that the utility model uses an extractive distillation baffle tower 1 to perform an extractive distillation operation of an ethanol-normal hexane-cyclohexane multinary azeotrope, saving a distillation tower device and a reboiler, saving energy and reducing consumption. In addition, when the method of the utility model is used to separate the ethanol-normal hexane-cyclohexane multinary azeotrope, the extractant can be directly recycled, which reduces costs and also reduces environmental pollution; and the purity of the separated ethanol, normal hexane and cyclohexane products is greater than 0.999%, and the purity of the recovered extractant is greater than 0.9999%, which has the advantages of no need to introduce an azeotropic agent, high product purity, simple operation, and energy saving.

Claims

1. A device for separating ethanol-n-hexane-cyclohexane polybasic azeotrope, characterized in that: The invention comprises an extractive distillation baffle tower (1), wherein a baffle (101) is vertically arranged in the extractive distillation baffle tower (1), and the extractive distillation baffle tower (1) is divided into a main tower (102) and a sub-tower (103). The main tower (102) is connected to a multi-element azeotropic feed pipeline (2), an extractant feed pipeline (3) and a reboiler (104); the top of the main tower (102) is connected to a condenser (1021) via a pipeline. The condenser 1 (1021) is connected to the reflux tank 1 (1022) through a pipeline, the reflux tank 1 (1022) is connected to the reflux pipeline 1 (1023) and the cyclohexane extraction pipeline (4), the reflux pipeline 1 (1023) is connected to the reflux port of the main tower (102); the top of the auxiliary tower (103) is connected to the condenser 2 (1031) through a pipeline, the condenser 2 (1031) is connected to the reflux port of the main tower (102) through a pipeline, The second flow tank (1032) is connected to the second reflux tank (1032) with a second reflux pipeline (1033) and a normal hexane extraction pipeline (5), and the second reflux pipeline (1033) is connected to the reflux port of the auxiliary tower (103); the bottom of the extractive distillation baffle tower (1) is connected to the feed port of the solvent recovery tower (7) through the ethanol-extractant extraction pipeline (6), the solvent recovery tower (7) is connected to the second reboiler (701), the top of the solvent recovery tower (7) is connected to the third condenser (702) through a pipeline, the third condenser (702) is connected to the third reflux tank (703) through a pipeline, the third reflux tank (703) is connected to the third reflux pipeline (704) and the ethanol extraction pipeline (8), the third reflux pipeline (704) is connected to the reflux port of the solvent recovery tower (7), and the bottom of the solvent recovery tower (7) is connected to the extractant extraction pipeline (9).

2. The device for separating ethanol-n-hexane-cyclohexane polybasic azeotrope as claimed in claim 1, characterized in that: The extractant extraction pipeline (9) is connected to the extractant feed pipeline (3) of the main tower (102).

3. The device for separating ethanol-normal hexane-cyclohexane polybasic azeotrope as claimed in claim 2, characterized in that: The extractant extraction pipeline (9) is connected to a condenser four (901).

4. The device for separating ethanol-normal hexane-cyclohexane polybasic azeotrope as claimed in claim 1, characterized in that: The number of plates of the main tower (102) is 45-55, and the number of plates of the auxiliary tower (103) is 22-30.

5. The device for separating ethanol-n-hexane-cyclohexane multi-element azeotrope as claimed in claim 4, characterized in that: The multi-element azeotrope feed line (2) is connected to the 28th to 35th tray of the main tower (102), and the extractant feed line (3) is connected to the 4th to 10th tray of the main tower (102).

6. The device for separating ethanol-n-hexane-cyclohexane polyhydric azeotrope according to claim 1, 4 or 5, characterized in that: The number of plates of the solvent recovery tower (7) is 15-25, and the ethanol-extractant extraction pipeline (6) is connected to the 10-18 plate of the solvent recovery tower (7).

7. The device for separating ethanol-n-hexane-cyclohexane multi-element azeotrope according to claim 1, characterized in that: The extractant in the extractant feed pipeline (3) is butyl butyrate.

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