CN113620772A - Cyclohexane multi-effect distillation method and device - Google Patents
Cyclohexane multi-effect distillation method and device Download PDFInfo
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- CN113620772A CN113620772A CN202010379376.3A CN202010379376A CN113620772A CN 113620772 A CN113620772 A CN 113620772A CN 202010379376 A CN202010379376 A CN 202010379376A CN 113620772 A CN113620772 A CN 113620772A
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Abstract
The invention discloses a multi-effect cyclohexane distillation method and a multi-effect cyclohexane distillation device. The method comprises the following steps: carrying out pre-distillation and N-stage multi-effect distillation on the ketone alcohol cyclohexane dilute solution to obtain cyclohexane, wherein N is not less than 2 and is an integer; in the N-stage multi-effect distillation, gas phase substances at the top of the tower, which are extracted from a first-stage distillation tower to an N-1-stage distillation tower, are heat sources of a next-stage distillation tower; the gas phase substance at the top of the tower extracted from the Nth-stage distillation tower is directly or after being pressurized as the heat source of the pre-distillation tower. Oxidizing cyclohexane to obtain a mixed material containing cyclohexane, cyclohexanone and cyclohexanol, feeding the treated dilute ketol cyclohexane solution into a pre-distillation tower, and using the gas phase at the top of a final effect distillation tower of the multi-effect distillation of the cyclohexane as a heat source to obtain the ketol cyclohexane solution with improved concentration.
Description
Technical Field
The invention belongs to the field of cyclohexane distillation, and particularly relates to a multi-effect cyclohexane distillation method and a multi-effect cyclohexane distillation device.
Background
With the rapid development of chemical fiber industry in China, the yield of caprolactam is increased year by year, and the demand of cyclohexanone as a caprolactam raw material is increased day by day. The cyclohexane oxidation method for preparing cyclohexanone has a single-pass conversion rate of only about 5%, and about 95% of cyclohexane needs to be recycled by distillation separation, so that 60% of steam required by a device is consumed, and the energy consumption of cyclohexane distillation directly influences the production cost of cyclohexanone.
Disclosure of Invention
The invention provides a multi-effect cyclohexane distillation method, which comprises the following steps:
the ketone alcohol cyclohexane dilute solution passes through a pre-distillation section and an N-stage multi-effect distillation section to obtain cyclohexane, wherein N is not less than 2 and is an integer;
in the N-stage multi-effect distillation section, gas phase substances at the top of the tower, which are extracted from the first-stage to the N-1-stage distillation tower, are heat sources of the next-stage distillation tower; the gas phase substance at the top of the tower extracted from the Nth-stage distillation tower is directly or after being pressurized as the heat source of the pre-distillation tower of the pre-distillation section.
According to an embodiment of the invention, N ═ 2, 3, or 4.
According to the embodiment of the invention, the ketone alcohol cyclohexane dilute solution passes through the pre-distillation section, cyclohexane is obtained at the top of the tower, and ketone alcohol cyclohexane solution with increased concentration is obtained at the bottom of the tower.
According to an embodiment of the invention, the diluted ketol-cyclohexane solution is an oxidation reaction product obtained by contacting cyclohexane with molecular oxygen, wherein the oxidation reaction product contains cyclohexanone, cyclohexanol and cyclohexane.
According to an embodiment of the invention, the ketone alcohol cyclohexane solution with increased concentration is used as feed to a first distillation column of a multi-effect distillation section.
According to the embodiment of the invention, the gas phase substances extracted from the top of the first-stage to the N-1-stage distillation tower exchange heat with the tower bottom liquid of the next-stage distillation tower to obtain the condensate and the temperature-raising tower bottom liquid.
According to an embodiment of the invention, the condensate is refluxed to the upper part of the distillation column of the stage or withdrawn.
According to an embodiment of the present invention, the warming column bottoms is returned to the next-stage distillation column bottoms.
According to the embodiment of the invention, the gas phase at the top of the Nth-stage distillation tower exchanges heat with the tower bottom liquid of the pre-distillation tower directly or after being pressurized, so as to obtain the Nth-stage condensate and the tower bottom liquid of the pre-distillation tower.
According to an embodiment of the present invention, the overhead vapor of the nth stage distillation column may be pressurized by a compressor. Preferably, the pressure ratio is 1.1-5, such as 1.5-3, exemplary 1.1, 1.3, 1.5, 2, 3, 4, 5.
According to an embodiment of the present invention, the nth stage condensate is refluxed to an upper part of the nth stage distillation column or withdrawn.
According to an embodiment of the invention, the pre-distillation column warming bottom liquid is returned to the pre-distillation column bottom.
According to an embodiment of the invention, the bottom of the multi-effect distillation first stage distillation column is provided by an external heat source.
According to an embodiment of the invention, the bottom draw of the preceding distillation column is multi-effect distilled as the feed to the next distillation column.
According to an embodiment of the invention, the overhead gas phase of the pre-distillation column is condensed and then refluxed to the upper part of the pre-distillation column or withdrawn.
According to an embodiment of the invention, in the N-stage multi-effect distillation section, the operating pressure at the top of the distillation column decreases sequentially from the first stage to the N-th stage. For example, the operating pressure difference at the top of the distillation column of two adjacent stages from the first stage to the Nth stage is 0.1 to 0.3MPa, such as 0.15 to 0.25MPa, illustratively 0.1MPa, 0.12MPa, 0.15MPa, 0.18MPa, 0.2MPa, 0.22MPa, 0.25MPa, 0.3MPa, respectively.
According to the embodiment of the invention, when the tower top gas phase of the Nth-stage distillation tower directly exchanges heat with the tower bottom liquid of the pre-distillation tower, the tower top operation pressure of the pre-distillation tower is lower than that of the Nth-stage distillation tower. For example, the operating pressure difference at the top of the column is 0.03 to 0.08MPa, such as 0.04 to 0.07MPa, illustratively 0.03MPa, 0.04MPa, 0.05MPa, 0.053MPa, 0.06MPa, 0.07 MPa.
According to the embodiment of the invention, when the tower top gas phase of the Nth-stage distillation tower is pressurized and then exchanges heat with the tower bottom liquid of the pre-distillation tower, the tower top operating pressure of the pre-distillation tower is greater than or equal to the tower top operating pressure of the Nth-stage distillation tower.
According to an embodiment of the present invention, the cyclohexane multi-effect distillation method comprises the steps of: the ketone alcohol cyclohexane dilute solution passes through a pre-distillation section and a tower kettle to obtain a ketone alcohol cyclohexane solution with increased concentration, and the ketone alcohol cyclohexane solution with increased concentration passes through a three-effect distillation section to obtain cyclohexane;
in the three-effect distillation section, after heat exchange is carried out between a gas phase substance at the top of the tower extracted from the first-stage distillation tower and a tower bottom liquid of the second-stage distillation tower, a first-stage condensate and a second-stage heating tower bottom liquid are obtained, the first-stage condensate flows back to the upper part of the first-stage distillation tower or is extracted, and the second-stage heating tower bottom liquid returns to the tower bottom of the second-stage distillation tower;
exchanging heat between the gas phase at the top of the second-stage distillation tower and the tower bottom liquid of the third-stage distillation tower to obtain a second-stage condensate and a third-stage heating tower bottom liquid, wherein the second-stage condensate flows back to the upper part of the second-stage distillation tower or is extracted, and the third-stage heating tower bottom liquid returns to the tower bottom of the third-stage distillation tower;
and exchanging heat between the gas phase at the top of the tower extracted by the third-stage distillation tower and the tower bottom liquid of the pre-distillation tower of the pre-distillation section to obtain third-stage condensate and the tower bottom liquid of the pre-distillation tower, wherein the third-stage condensate flows back to the upper part of the third-stage distillation tower or is extracted, and the tower bottom liquid of the pre-distillation tower is returned to the tower bottom of the pre-distillation tower.
The present invention also provides a multi-effect distillation apparatus for cyclohexane, the apparatus comprising: the system comprises a pre-distillation unit and an N-stage multi-effect distillation unit, wherein the pre-distillation unit comprises a pre-distillation tower and a pre-distillation tower reboiler arranged at a tower bottom, and the N-stage multi-effect distillation unit comprises first to N-th stages of distillation towers and reboilers arranged at tower bottoms of the distillation towers; wherein N is not less than 2 and is an integer;
the tower bottom of the pre-distillation tower is connected with the tower upper part of the first-stage distillation tower;
a gas phase extraction outlet at the top of the distillation tower from the first stage to the N-1 stage is connected with a heat exchange medium inlet of a next stage distillation reboiler, and the heat exchange medium outlet is connected with the upper part of the distillation tower where the gas phase extraction outlet is positioned or is connected with an external pipeline;
the gas phase extraction outlet at the top of the Nth-stage distillation tower is directly connected with a heat exchange medium inlet of a pre-distillation tower reboiler or is connected with the upper part of the Nth-stage distillation tower or an external pipeline through a compressor.
According to an embodiment of the invention, N ═ 2, 3, or 4.
According to an embodiment of the invention, a condenser is arranged at the top of the pre-distillation column.
Furthermore, a material inlet of the condenser is connected with a gas phase extraction outlet of the pre-distillation tower, and a material outlet is connected with the upper part of the pre-distillation tower or an external pipeline.
According to the embodiment of the invention, the bottom material taking-out ports of the first to N-1 st-stage distillation columns are connected to the middle part of the next-stage distillation column.
According to an embodiment of the invention, the cyclohexane multi-effect distillation apparatus comprises: the device comprises a pre-distillation unit and a triple-effect distillation unit, wherein the pre-distillation unit comprises a pre-distillation tower and a pre-distillation tower reboiler arranged at a tower bottom, and the triple-effect distillation unit comprises first-stage to third-stage distillation towers and reboilers arranged at tower bottoms of the distillation towers;
the tower bottom of the pre-distillation tower is connected with the middle part of the first-stage distillation tower;
a tower top gas phase extraction outlet from the first-stage distillation tower to the second-stage distillation tower is connected with a heat exchange medium inlet of a reboiler of the next-stage distillation tower, and the heat exchange medium outlet is connected with the upper part of the distillation tower where the gas phase extraction outlet is positioned or is connected with an external pipeline;
and a tower top gas phase extraction outlet of the third-stage distillation tower is connected with a heat exchange medium inlet of a pre-distillation tower reboiler, and a heat exchange medium outlet is connected with the upper part of the third-stage distillation tower or an external pipeline.
The invention has the beneficial effects that:
according to the invention, cyclohexane is oxidized to obtain a mixed material containing cyclohexane, cyclohexanone and cyclohexanol, the treated dilute ketol cyclohexane solution is sent to a pre-distillation tower, the gas phase at the top of a last-effect distillation tower of multi-effect distillation of cyclohexane is used as a heat source to obtain the ketol cyclohexane solution with improved concentration, and the ketol cyclohexane solution with improved concentration is used as the feeding material of a first-stage distillation tower, so that the feeding concentration of the ketol cyclohexane solution entering a cyclohexane multi-effect distillation device is improved.
The gas phase at the top of the first-level to the N-1-level distillation tower is used as the heat source of the next-level distillation tower, and the gas phase at the top of the last-effect distillation tower is used as the heat source of the pre-distillation tower, so that the heat in the gas phase at the top of the multi-effect distillation tower is fully utilized, and the energy is saved.
Drawings
Fig. 1 is a multi-effect cyclohexane distillation apparatus provided in example 1.
Reference numerals: A. compressor, T, pre-distillation tower, T1, first tower, T2, second tower, T3, third tower, B, pre-distillation tower reboiler, B11, first tower reboiler, B22, second tower reboiler, B32, third tower reboiler, C, pre-distillation tower condenser,
1. dilute ketol cyclohexane solution, 2, gas phase material flow at the top of the pre-distillation tower, 3, ketol cyclohexane solution with increased concentration, 5, condensate extracted from the pre-distillation tower, 6, reflux extracted from the pre-distillation tower, 7, tower bottom extracted from the pre-distillation tower, 12, gas phase material flow at the top of the first tower, 13, tower bottom discharged material, 14, tower condensate, 15, condensate extracted from the first tower, 16, tower reflux extracted from the first tower, 17, tower bottom extracted from the reboiler, 22, gas phase material flow at the top of the second tower, 23, tower bottom discharged material flow at the bottom of the second tower, 24, reboiler extracted from the second tower, 25, condensate extracted from the second tower, 26, tower reflux extracted from the second tower, 27, tower bottom extracted from the second tower, 32, gas phase material flow at the top of the third tower, 33, tower bottom discharged material flow at the bottom of the third tower, 34, gas phase material flow at the top of the third tower, 35, gas phase material flow extracted from the third tower, 36, gas phase material flow at the reboiler extracted from the third tower, 37, tower, reboiler introduced into the third tower, 38, and pressurized gas phase material flow of the third tower.
Detailed Description
The technical solution of the present invention will be further described in detail with reference to specific embodiments. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
Unless otherwise indicated, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.
Example 1
The cyclohexane multi-effect distillation device shown in figure 1 comprises a pre-distillation unit and a three-effect distillation unit.
The pre-distillation unit comprises a pre-distillation tower T, a pre-distillation tower reboiler B arranged at a tower kettle, and a pre-distillation tower condenser C arranged at the tower top, wherein a material inlet of the pre-distillation tower condenser C is connected with a tower top gas phase outlet of the pre-distillation tower T, and a material outlet of the pre-distillation tower condenser C is provided with two branches: one is connected with the upper part of the pre-distillation tower T, and the other is connected with an external pipeline.
The triple-effect distillation unit comprises a tower T1, a tower T2 and a tower T3, wherein the tower kettle of each tower is provided with a reboiler.
The bottom of the pre-distillation tower T is connected with the feed inlet of a first tower T1, the top gas phase outlet of the first tower T1 is connected with the heat exchange medium inlet of a second tower reboiler B22, and the heat exchange medium outlet of the second tower reboiler B22 is provided with two branches: one connected to the upper part of a column T1 and one connected to the external piping. The reboiler B11 of the first tower is supplied with heat by an external heat source, and the material taking outlet of the bottom of the first tower T1 is connected with the material inlet of the second tower T2.
The outlet of the gas phase at the top of the second tower T2 is connected with the inlet of the heat exchange medium of the third tower reboiler B32, and the outlet of the heat exchange medium of the third tower reboiler B32 is provided with two branches: one is connected with the upper part of the second tower T2, and the other is connected with an external pipeline. The bottom material taking-out port of the second tower T2 is connected with the feed inlet of the third tower T3.
The top gas phase outlet of the three-tower T3 is connected with the inlet of a compressor A, the outlet of the compressor is connected with the heat exchange medium inlet of a pre-distillation tower reboiler B, and the heat exchange medium outlet of the pre-distillation tower reboiler B is provided with two branches: one connected to the upper part of the three-column T3 and the other connected to an external pipeline.
Example 2
Cyclohexane was distilled using the apparatus of example 1, as follows:
(1) cyclohexane is oxidized to obtain a mixed material containing cyclohexane, cyclohexanone and cyclohexanol, and the mixed material is treated to obtain a diluted ketol cyclohexane solution 1.
(2) And (2) feeding the diluted ketol cyclohexane solution 1 in the step (1) into a pre-distillation tower T, using a pressurized gas phase material flow 38 of a gas phase material flow 32 at the top of the three towers as a heat source in a reboiler B of the pre-distillation tower to exchange heat with tower bottom liquid 7 of the pre-distillation tower to obtain three-tower condensate 34, and taking part of the three-tower condensate 34 as three-tower reflux liquid 36 to return to the three towers, and taking part of the three-tower condensate as three-tower extraction condensate 35 to extract. And (3) exchanging heat of the gas phase material flow 2 at the top of the pre-distillation tower, returning a part of the gas phase material flow to the pre-distillation tower T as reflux liquid 6 of the pre-distillation tower, and taking a part of the gas phase material flow as the condensate 5 extracted from the pre-distillation tower. The bottom of the predistillation column T gives a ketone alcohol cyclohexane solution 3 of increasing concentration.
(3) The ketol cyclohexane solution 3 with increased concentration is sent into a first tower T1, tower bottoms 17 of the first tower enters a reboiler, the tower bottoms are heated by an external heat source, and tower bottom discharge 13 of the first tower is sent into a second tower T2. The gas phase material flow 12 at the top of the first tower exchanges heat with tower bottom liquid 27 of the second tower entering a reboiler to obtain first tower condensate 14, wherein one part of the first tower condensate is returned to the first tower as first tower reflux liquid 16, and one part of the first tower condensate is extracted as first tower extraction condensate 15.
And (3) feeding the bottom discharge 23 of the second tower into a third tower T3, exchanging heat between the gas-phase material flow 22 at the top of the second tower and tower bottoms 37 of the third tower entering a reboiler to obtain second tower condensate 24, returning one part of the second tower condensate to the second tower as second tower reflux liquid 26, and extracting one part of the second tower condensate as third tower produced condensate 25.
The material 33 extracted from the bottom of the three-tower is a ketol mixture.
Wherein the first tower condensate, the second tower condensate and the third tower condensate are cyclohexane.
The gas phase material flow at the top of the three towers with the pressure of 0.11MPa is pressurized by a compressor to obtain the pressurized gas phase material flow 38 with the pressure of 0.195 MPa.
T1, T2 and T3 are cyclohexane triple effect distillation columns, and T is a preliminary distillation column. The column operating conditions are as follows:
| tower with a tower body | T | T1 | T2 | T3 |
| The temperature at the top of the column is lower | 83 | 142 | 122 | 84 |
| Pressure MPa at the top of the column | 0.11 | 0.5 | 0.3 | 0.11 |
| Column bottom temperature deg.C | 95 | 146 | 125 | 95 |
| Reflux ratio | 0.5 | 0.7 | 0.7 | 0.5 |
Example 3
The pre-distillation column T reboiler uses the three overhead vapor stream 32 directly as the heat source.
T1, T2 and T3 are cyclohexane triple effect distillation columns, and T is a preliminary distillation column. The column operating conditions are as follows:
| tower with a tower body | T | T1 | T2 | T3 |
| The temperature at the top of the column is lower | 61 | 142 | 122 | 84 |
| Pressure MPa at the top of the column | 0.057 | 0.5 | 0.3 | 0.11 |
| Column bottom temperature deg.C | 65 | 146 | 125 | 95 |
| Reflux ratio | 0.5 | 0.7 | 0.7 | 0.5 |
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A multi-effect distillation method for cyclohexane is characterized by comprising the following steps:
the ketone alcohol cyclohexane dilute solution is subjected to pre-distillation and then N-stage multi-effect distillation to obtain cyclohexane and a ketone alcohol solution, wherein N is not less than 2 and is an integer;
in the N-stage multi-effect distillation, gas phase substances at the top of the tower, which are extracted from a first-stage distillation tower to an N-1-stage distillation tower, are heat sources of a next-stage distillation tower; the gas phase substance at the top of the tower extracted from the Nth-stage distillation tower is directly or after being pressurized as the heat source of the pre-distillation tower.
2. The method of claim 1, wherein the dilute ketol-cyclohexane solution is an oxidation reaction product obtained by contacting cyclohexane with molecular oxygen, wherein the oxidation reaction product comprises cyclohexanone, cyclohexanol and cyclohexane.
Preferably, N ═ 2, 3, or 4.
Preferably, the ketone alcohol cyclohexane dilute solution is subjected to pre-distillation, cyclohexane is obtained at the top of the tower, and ketone alcohol cyclohexane solution with increased concentration is obtained at the bottom of the tower.
Preferably, the increased concentration ketol cyclohexane solution is used as a feed to a multi-effect distillation first stage distillation column.
3. The method according to claim 1 or 2, wherein the gas phase at the top of the first-stage to the N-1-stage distillation tower exchanges heat with the bottom liquid of the next-stage distillation tower to obtain a condensate and a warming tower bottom liquid.
Preferably, the condensate is refluxed to the upper part of the distillation column of the stage or withdrawn.
Preferably, the tower bottom liquid of the heating tower returns to the tower bottom of the next-stage distillation tower.
4. The method according to any one of claims 1 to 3, wherein the gas phase at the top of the N-stage distillation tower exchanges heat with the tower bottom liquid of the pre-distillation tower directly or after being pressurized to obtain the N-stage condensate and the tower bottom liquid of the pre-distillation tower.
Preferably, the overhead vapor of the nth stage distillation column is pressurized by a compressor. Preferably, the pressure ratio is 1.1 to 5.
Preferably, the Nth stage condensate is refluxed to the upper part of the Nth stage distillation tower or is extracted.
Preferably, the bottom liquid of the pre-distillation tower heating tower returns to the bottom of the pre-distillation tower.
Preferably, the tower bottom of the multi-effect distillation first-stage distillation tower is provided by an external heat source.
Preferably, the bottom product of the previous stage distillation tower is distilled by multiple effect as the feed of the next stage distillation tower.
Preferably, the gas phase at the top of the pre-distillation tower is condensed and then refluxed to the upper part of the pre-distillation tower or extracted.
5. The method according to any one of claims 1 to 4, wherein in the N-stage multi-effect distillation, the operation pressure at the top of the distillation tower is reduced from the first stage to the Nth stage.
Preferably, when the tower top gas phase of the Nth stage distillation tower directly exchanges heat with the tower bottom liquid of the pre-distillation tower, the tower top operating pressure of the pre-distillation tower is lower than that of the Nth stage distillation tower.
Preferably, when the tower top gas phase of the Nth-stage distillation tower is pressurized and then exchanges heat with the tower bottom liquid of the pre-distillation tower, the tower top operating pressure of the pre-distillation tower is greater than or equal to the tower top operating pressure of the Nth-stage distillation tower.
6. A multi-effect distillation process of cyclohexane as claimed in any one of claims 1 to 5, characterized in that it comprises the following steps: the ketone alcohol cyclohexane dilute solution is pre-distilled, a ketone alcohol cyclohexane solution with increased concentration is obtained at the tower bottom, and cyclohexane is obtained by triple effect distillation of the ketone alcohol cyclohexane solution with increased concentration;
in the three-effect distillation, a gas phase substance at the top of the tower, which is extracted from a first-stage distillation tower, exchanges heat with a tower bottom liquid of a second-stage distillation tower to obtain a first-stage condensate and a second-stage heating tower bottom liquid, wherein the first-stage condensate flows back to the upper part of the first-stage distillation tower or is extracted, and the second-stage heating tower bottom liquid returns to the tower bottom of the second-stage distillation tower;
exchanging heat between the gas phase at the top of the second-stage distillation tower and the tower bottom liquid of the third-stage distillation tower to obtain a second-stage condensate and a third-stage heating tower bottom liquid, wherein the second-stage condensate flows back to the upper part of the second-stage distillation tower or is extracted, and the third-stage heating tower bottom liquid returns to the tower bottom of the third-stage distillation tower;
and exchanging heat between the gas phase at the top of the tower extracted by the third-stage distillation tower and the tower bottom liquid of the pre-distillation tower of the pre-distillation section to obtain third-stage condensate and the tower bottom liquid of the pre-distillation tower, wherein the third-stage condensate flows back to the upper part of the third-stage distillation tower or is extracted, and the tower bottom liquid of the pre-distillation tower is returned to the tower bottom of the pre-distillation tower.
7. A multi-effect cyclohexane distillation apparatus, comprising: the system comprises a pre-distillation unit and an N-stage multi-effect distillation unit, wherein the pre-distillation unit comprises a pre-distillation tower and a pre-distillation tower reboiler arranged at a tower bottom, and the N-stage multi-effect distillation unit comprises first to N-th stages of distillation towers and reboilers arranged at tower bottoms of the distillation towers; wherein N is not less than 2 and is an integer;
the tower bottom of the pre-distillation tower is connected with the middle part of the first-stage distillation tower;
a gas phase extraction outlet at the top of the first-stage to the N-1-stage distillation tower is connected with a heat exchange medium inlet of a reboiler of the next-stage distillation tower, and the heat exchange medium outlet is connected with the upper part of the distillation tower where the gas phase extraction outlet is positioned or is connected with an external pipeline;
the gas phase extraction outlet at the top of the Nth-stage distillation tower is directly connected with a heat exchange medium inlet of a pre-distillation tower reboiler or is connected with the upper part of the Nth-stage distillation tower or an external pipeline through a compressor.
8. The apparatus of claim 7, wherein N-2, 3, or 4.
Preferably, the bottom material taking-out ports of the first to N-1 st-stage distillation columns are connected with the upper part of the next-stage distillation column.
9. The apparatus according to claim 7 or 8, wherein a condenser is provided at the top of the preliminary distillation column.
Preferably, a material inlet of the condenser is connected with a gas phase extraction outlet of the pre-distillation tower, and a material outlet is connected with the upper part of the pre-distillation tower or an external pipeline.
10. A cyclohexane multi-effect distillation apparatus as claimed in any one of claims 7 to 9, characterized in that the apparatus comprises: the device comprises a pre-distillation unit and a triple-effect distillation unit, wherein the pre-distillation unit comprises a pre-distillation tower and a pre-distillation tower reboiler arranged at a tower bottom, and the triple-effect distillation unit comprises first-stage to third-stage distillation towers and reboilers arranged at tower bottoms of the distillation towers;
the tower bottom of the pre-distillation tower is connected with the middle part of the first-stage distillation tower;
a tower top gas phase extraction outlet from the first-stage distillation tower to the second-stage distillation tower is connected with a heat exchange medium inlet of a reboiler of the next-stage distillation tower, and the heat exchange medium outlet is connected with the upper part of the distillation tower where the gas phase extraction outlet is positioned or is connected with an external pipeline;
and a tower top gas phase extraction outlet of the third-stage distillation tower is connected with a heat exchange medium inlet of a pre-distillation tower reboiler, and a heat exchange medium outlet is connected with the upper part of the third-stage distillation tower or an external pipeline.
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| 范会芳等: "环己酮装置环己烷精馏工段的模拟与优化", 化学工程, vol. 39, no. 8, pages 6 - 10 * |
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