CN108976115B - Method and system for separating cyclohexane and acetic acid - Google Patents
Method and system for separating cyclohexane and acetic acid Download PDFInfo
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Abstract
The invention relates to a method for separating cyclohexane and acetic acid, heating a mixed solution of cyclohexane and acetic acid to make the mixed solution azeotropic; adding water into an azeotropic system of cyclohexane and acetic acid, and controlling the temperature of the system to be 69.4-69.6 ℃; the cyclohexane-water forms an azeotrope and is separated from the acetic acid; collecting cyclohexane-water azeotrope, cooling and separating to obtain cyclohexane. The invention also discloses a system for separating cyclohexane and acetic acid. The method adopts water as an entrainer, the separation of cyclohexane and acetic acid is completed in a rectifying tower, the water phase at the top of the tower returns to the rectifying tower to carry out circulating azeotropic distillation with the cyclohexane, the azeotropic distillation of the cyclohexane and the acetic acid is reduced or eliminated, the cyclohexane with the acetic acid content of 1-100 ppm is obtained at the top of the tower, and the acetic acid with the mass concentration of more than 99.5 percent is obtained at the bottom of the tower. The invention has simple process and low energy and material consumption.
Description
Technical Field
The invention relates to a method and a device for separating cyclohexane and acetic acid; belongs to the field of petrochemical engineering technology development.
Background
Cyclohexanol, cyclohexanone and adipic acid are raw materials for preparing nylon 6 and nylon 66, benzene is generally adopted as a raw material in the production process of the cyclohexanol, the cyclohexanone and the adipic acid, intermediate products such as cyclohexane and cyclohexene are obtained through hydrogenation, products such as the cyclohexanol, the cyclohexanone and the adipic acid are obtained through oxidation of the cyclohexane, and the cyclohexanol is obtained through esterification and hydrogenation of the cyclohexene.
In the above production process, there is a technical problem of separation of cyclohexane and acetic acid, and the conventional distillation technique is difficult to separate because of the azeotropic generation during distillation of cyclohexane and acetic acid.
In order to solve the separation problem of cyclohexane and acetic acid, a water washing or extractive distillation method is generally adopted, and a large amount of low-value dilute acetic acid is generated when water washing separation is adopted; when the extractive distillation is adopted, the separation process is long, and the energy consumption and material consumption are high.
Patent CN104829408B relates to a separation method of cyclohexane and ethyl acetate, which adopts phenol as an extractant of an extractive distillation column, extracts ethyl acetate to a common distillation column for distillation and separation, and recycles the extractant phenol at the bottom of the column. This technique is a typical extractive distillation separation process.
Patent CN1270578A relates to a method and apparatus for removing acetic acid from cyclohexane in the direct oxidation of cyclohexane to adipic acid. And removing acetic acid in cyclohexane by using secondary or tertiary water washing, and removing water from the water-containing acetic acid by azeotropic distillation. The process has long flow and high energy consumption.
Disclosure of Invention
The invention provides a method for separating cyclohexane and acetic acid, which aims at overcoming the defects of the prior art.
In addition, the invention also provides a separation system for implementing the method.
A method for separating cyclohexane and acetic acid comprises heating a mixed solution of cyclohexane and acetic acid to make the mixed solution azeotropic; adding water into an azeotropic system of cyclohexane and acetic acid, and controlling the temperature of the system to be 69.4-69.6 ℃ of the azeotropic temperature of the water and the cyclohexane; the cyclohexane-water forms an azeotrope and is separated from the acetic acid; collecting cyclohexane-water azeotrope, cooling and separating to obtain cyclohexane.
In the method of the present invention, water is added to an azeotropic system of cyclohexane and acetic acid, and the temperature is strictly controlled at the temperature, so that the azeotropic system of cyclohexane and acetic acid is converted into an azeotropic system of cyclohexane and water, thereby separating acetic acid from cyclohexane. Collecting an azeotropic system of cyclohexane and water, cooling, and separating oil from water to obtain an oil phase, namely cyclohexane. By adopting the method, the separation of cyclohexane and acetic acid can be realized only by one set of equipment with the heating function. The method is simple and the equipment investment is small; compared with the existing separation method, a series of problems of emulsification, appearance of a third phase, low separation efficiency, large water consumption, low concentration of recovered acid, poor recycling effect and the like which possibly exist in the prior art are avoided.
The inventor finds that the temperature is controlled within 69.4-69.6 ℃ of the azeotropic temperature of water and cyclohexane after water is added, so that the method not only is beneficial to reducing the acetic acid content of the cyclohexane obtained by separation, but also can reduce the water content of the acetic acid obtained by separation, and improves the quality of the recovered acetic acid.
Further preferably, the temperature is controlled to be 69.4-69.5 ℃.
The process of the present invention can theoretically treat a mixed solution of cyclohexane and acetic acid in any mass ratio.
Preferably, the initial mass concentration of acetic acid in the mixed solution of cyclohexane and acetic acid is 10-95%. The starting mass concentration of acetic acid refers to the mass percent of acetic acid in the starting materials of cyclohexane and acetic acid.
Preferably, the initial mass concentration of acetic acid in the mixed solution of cyclohexane and acetic acid is 10-50%.
Preferably, the water obtained by cooling and separating an azeotropic system of cyclohexane and water is recycled.
Preferably, the mass concentration of the added water is 98-99.9%.
Preferably, the oil phase part obtained by condensing the cyclohexane-water azeotropic system is recycled. Thus, the rectification effect can be further improved.
Preferably, the oil phase reflux ratio is less than or equal to 30 (i.e., 0 to 30). The reflux ratio is as follows: the ratio between cyclohexane derived from the cyclohexane-water azeotrope and recycled cyclohexane. When the oil phase reflux ratio is 0, it is considered that the oil phase is not circulated.
Further preferably, the oil phase reflux ratio is 1-10; more preferably 1 to 2.
The cyclohexane and acetic acid separation process of the present invention is preferably carried out in a vessel that can be warmed to the cyclohexane-water azeotropic temperature.
Preferably, the separation process of cyclohexane and acetic acid according to the invention is carried out in a rectification column.
According to the invention, raw materials of cyclohexane and acetic acid are placed in a rectifying tower, the temperature is raised to enable the cyclohexane and the acetic acid to form a cyclohexane-acetic acid azeotropic system (atmosphere) at the top of the rectifying tower, water is added into the azeotropic system, the temperature at the top of the rectifying tower is controlled to be 69.4-69.6 ℃ of the azeotropic temperature of water and cyclohexane, and the cyclohexane-acetic acid azeotropic system is converted into the cyclohexane-water azeotropic system. And leading out an azeotropic system of cyclohexane and water from the top of the rectifying tower, condensing and separating to obtain cyclohexane. The remaining solution of the rectification column is acetic acid.
By adopting the method, the separation of cyclohexane and acetic acid can be completed by adopting a set of equipment; compared with the prior art, the method of the invention does not need a large amount of water, and has lower cost; in addition, the cyclohexane is separated from the acetic acid from the top of the rectifying tower.
The method adopts water as an entrainer, the separation of cyclohexane and acetic acid is completed in a rectifying tower, a water phase at the top of the tower returns to the rectifying tower to carry out circulating azeotropic distillation with the cyclohexane, the azeotropic distillation of the cyclohexane and the acetic acid is reduced or eliminated, the cyclohexane with the acetic acid content of 1-100 ppm is obtained at the top of the tower, and the acetic acid with the mass concentration of more than 99.5 percent is obtained at a tower kettle; the purity of water obtained by separating the water phase at the top of the tower can be kept between 98 and 99.9 percent; the method of the invention has excellent separation effect of cyclohexane and acetic acid.
The invention also provides a system for separating cyclohexane and acetic acid, which comprises a rectifying tower, a tower top condenser, an oil-water phase separation tank, a tower top water phase reflux pump, a tower top oil phase reflux pump and a tower bottom cooler;
the rectifying tower comprises a rectifying section and a stripping section, and the bottom of the rectifying tower is connected with a tower bottom reboiler; the rectifying tower is provided with a feed inlet, the top of the rectifying tower is provided with a cyclohexane-water azeotrope outlet, the bottom of the rectifying tower is provided with an acetic acid outlet, and the rectifying section is also provided with a reflux inlet;
the outlet of the cyclohexane-water azeotrope is connected with the azeotrope inlet of the oil-water phase-splitting tank, and the connecting pipeline is provided with an overhead condenser;
the oil-water phase separation tank is also provided with a water injection port, a water outlet and an oil phase outlet; the water outlet is connected with the reflux inlet of the rectifying tower, and the oil phase outlet is connected with the cyclohexane storage tank.
The acetic acid outlet of the rectifying tower is connected with an acetic acid storage tank, and a tower bottom condenser is arranged on the connecting pipeline.
Preferably, the feed inlet of the rectifying tower is arranged between the rectifying section and the stripping section.
Preferably, the water outlet of the oil-water phase separation tank is communicated with the reflux inlet of the rectifying tower through a tower top aqueous phase reflux pump.
Preferably, the oil phase outlet is connected to the reflux inlet of the rectifying column via a column top oil phase reflux pump.
Preferably, the rectifying section and the stripping section of the rectifying tower are both filled with metal titanium theta rings.
The invention also provides an application method of the system for separating cyclohexane and acetic acid, which comprises the following steps:
the method comprises the following steps: under normal pressure, adding a mixture of cyclohexane and acetic acid from a feed inlet of a rectifying tower, and adding water into a water phase region of an oil-water phase separation tank;
step two: heating a reboiler at the bottom of the tower to increase the temperature, starting a water phase reflux pump at the top of the tower when the material is discharged from the top of the tower, adjusting the reflux flow of the water phase, and controlling the upper temperature of a rectifying section of the rectifying tower to be 69.4-69.6 ℃ of the azeotropic temperature of water and cyclohexane; starting an oil phase reflux pump at the top of the tower, and controlling the oil phase reflux ratio to be less than or equal to 30;
step three: continuously extracting cyclohexane from an oil phase outlet of the oil-water phase separation tank; and (3) extracting acetic acid from an acetic acid outlet of the rectifying tower.
Preferably, in the first step, the liquid level of the bottom of the rectifying tower is controlled to be 50-60%; and the water phase liquid level in the water phase area of the oil-water phase separation tank is 30-50%.
Preferably, the water phase level of the water phase region of the oil-water phase separation tank is controlled by adding water.
Preferably, the mass concentration of water in the water phase in the oil-water phase separation tank is 98-99.9%.
Preferably, in the second step, the temperature of the upper part of the rectifying section of the rectifying tower is controlled to be 69.4-69.6 ℃; further preferably 69.4 to 69.5 ℃.
Namely, the temperature of the material output from the outlet of the cyclohexane-water azeotrope is controlled to be 69.4-69.6 ℃.
Preferably, in the second step, the reflux flow of the water is 9.0-11.0% of the sum of the reflux of the oil phase at the top of the tower and the mass flow of the discharged material; more preferably 9.5 to 10.0%.
Preferably, in the second step, the oil phase reflux ratio is 1 to 10, and more preferably 1 to 2.
The invention relates to a more preferable application method of a system for separating cyclohexane and acetic acid, which comprises the following steps:
the method comprises the following steps:
under normal pressure, adding a mixture of cyclohexane and acetic acid from a feed inlet of a rectifying tower, establishing a tower kettle liquid level of 50-60%, and adding water into a water phase area of an oil-water phase separation tank (4) to establish a water phase liquid level of 30-50%;
step two:
a reboiler (8) at the bottom of the tower is heated to raise the temperature, when the material is discharged from the top of the tower, a water phase reflux pump (5) at the top of the tower is started, the reflux flow of the water phase is adjusted, and the temperature at the top of the rectification tower is controlled to be 69.4-69.6 ℃ of the azeotropic temperature of water and cyclohexane; gradually establishing an oil phase liquid level of 60-80% in the tower top oil-water phase-splitting tank (4), starting the tower top oil phase reflux pump (6), and controlling the oil phase reflux ratio to be 1-2;
step three:
continuously extracting cyclohexane from an oil phase outlet of the oil-water phase separation tank; acetic acid is extracted from an acetic acid outlet of the rectifying tower; the water phase level was controlled by adding additional water.
In industrial application, a mixture of cyclohexane and acetic acid enters a rectifying tower from a position between a stripping section (1) and a rectifying section (2), under the action of a tower kettle reboiler (8), the cyclohexane and the acetic acid are rectified and azeotroped to the upper part of the tower, mass transfer and heat exchange are carried out with an oil phase and a water phase which are refluxed at the top of the tower, an azeotrope of water and the cyclohexane is formed step by step and flows out of the top of the tower, the temperature of the top of the tower is about 69.4 ℃, the acid content in the discharged cyclohexane at the top of the tower is 1-100 ppm, the temperature of the bottom of the tower is about 118 ℃, and the mass concentration of the discharged acetic acid at the bottom of the tower is more than 99.5%.
Advantageous effects
The invention adopts the technical scheme that in a rectifying section in a rectifying tower, cyclohexane and acetic acid azeotropic gas phase is converted into cyclohexane and water azeotropic gas phase, so that the phase change latent heat of the acetic acid is fully utilized, the energy consumption for separating cyclohexane and acetic acid is reduced, the separation process is shortened, and the investment cost and the operation cost are reduced.
In the invention, water is added into an azeotropic system (atmosphere) of cyclohexane-acetic acid, the temperature is controlled, high-purity acetic acid can be separated, and the water content of the recovered acetic acid can be controlled below 0.5%; the purity of the recovered cyclohexane is high, and researches show that the acetic acid content of the cyclohexane obtained by separation can be controlled within 100 ppm.
Drawings
FIG. 1 is a schematic diagram of a process for removing acetic acid from cyclohexane in preparation of cyclohexyl acetate by reactive distillation according to a preferred embodiment of the present invention.
In fig. 1, 1 is a stripping section, 2 is a rectifying section, 3 is a tower top condenser, 4 is an oil-water phase separation tank, 5 is a tower top water phase reflux pump, 6 is a tower top oil phase reflux pump, 7 is a tower bottom cooler, and 8 is a tower bottom reboiler.
Detailed Description
The present invention will be specifically described with reference to examples, but the examples are not intended to limit the present invention.
The equipment and process used in the embodiment of the invention are shown in figure 1; the concrete parameters and materials are as follows:
the reaction rectifying tower of DN 100X 6000 is divided into two sections, wherein the upper section is a 4000mm rectifying section provided with 5mm metal titanium theta rings, and the lower section is a 2000mm stripping section provided with 5mm metal titanium theta rings. The top of the tower is provided with a condenser, an oil-water phase separating tank, an oil phase and a water phase reflux pump, and the water phase area of the oil-water phase separating tank is provided with a water replenishing pipe. The material inlet is positioned between the rectifying section 2 and the stripping section 1. The tower bottom is electrically heated, and the tower bottom material is cooled and then sent to a product barrel.
The system for separating cyclohexane and acetic acid comprises a rectifying tower, a tower top condenser 3, an oil-water phase separation tank 4, a tower top water phase reflux pump 5, a tower top oil phase reflux pump 6 and a tower bottom cooler 7;
the rectifying tower comprises a rectifying section 2 and a stripping section 1, and the bottom of the rectifying tower is connected with a tower bottom reboiler 8; the rectifying tower is provided with a feed inlet which is arranged between the rectifying section 2 and the stripping section 1. The top of the rectifying tower is provided with a cyclohexane-water azeotrope outlet, the bottom of the rectifying tower is provided with an acetic acid outlet, and the rectifying section 2 is also provided with a reflux inlet;
the outlet of the cyclohexane-water azeotrope is connected with the azeotrope inlet of the oil-water phase separation tank 4, and the connecting pipeline is provided with a tower top condenser 3;
the oil-water phase separation tank 4 is also provided with a water injection port, a water outlet and an oil phase outlet; the water outlet and the oil phase outlet are respectively or jointly connected with a reflux inlet of the rectifying tower; wherein, the water outlet of the oil-water phase separation tank 4 is communicated with the reflux inlet of the rectifying tower through a tower top water phase reflux pump 5. The oil phase outlet is communicated with the reflux inlet of the rectifying tower through an oil phase reflux pump 6 at the top of the tower.
The oil phase outlet is also connected with a cyclohexane storage tank.
The acetic acid outlet of the rectification column is connected to an acetic acid storage tank (product tank, not shown in fig. 1), and a column bottom condenser is disposed on the connecting pipeline.
Example 1
Step one
Under normal pressure, adding a mixture of 90% cyclohexane and 10% acetic acid by mass fraction from a feed inlet of a rectifying tower at a flow rate of 5kg/h, and establishing a tower kettle liquid level of 60%; and adding water into the water phase area of the oil-water phase separation tank (4) to establish the liquid level of the water phase at 30-50%.
Step two
A reboiler (8) at the bottom of the tower is heated to raise the temperature, when the material is discharged from the top of the tower, a reflux pump (5) of a water phase at the top of the tower is started, the reflux flow of the water phase is adjusted to be about 0.81kg/h (the reflux flow is 9 percent of the sum of the reflux flow of the oil phase at the top of the tower and the mass flow of the discharged material), and the temperature at the top of the rectifying tower is controlled to be 69.4 ℃ of the azeotropic temperature of water and cyclohexane; gradually establishing an oil phase liquid level of 60-80% of an oil phase tank (4) at the top of the tower, starting a reflux pump (6) of the oil phase at the top of the tower, controlling the reflux ratio of the oil phase to be 1, after stable operation, controlling the mass concentration of water in the water phase to be 99.9%, controlling the acid content of cyclohexane discharged at the top of the tower to be 1ppm, controlling the temperature of a tower kettle to be about 118 ℃, and controlling the mass concentration of acetic acid discharged at the tower kettle to be 99.5%.
Example 2
Step one
Under normal pressure, adding a mixture of cyclohexane with the mass fraction of 5% and acetic acid with the mass fraction of 95% from a feed inlet of a rectifying tower at the flow rate of 5kg/h, and establishing the liquid level of a tower kettle to be 60%; and adding water into the water phase area of the oil-water phase separation tank (4) to establish the liquid level of the water phase at 30-50%.
Step two
A reboiler (8) at the bottom of the tower is heated to raise the temperature, when the material is discharged from the top of the tower, a reflux pump (5) of a water phase at the top of the tower is started, the reflux flow of the water phase is adjusted to be about 0.76kg/h (the reflux flow is 10 percent of the sum of the reflux flow of the oil phase at the top of the tower and the mass flow of the discharged material), and the temperature at the top of the rectifying tower is controlled to be 69.6 ℃; gradually establishing an oil phase liquid level of 60-80% in an oil-water phase-separating tank (4) at the top of the tower, starting an oil phase reflux pump (6) at the top of the tower, controlling an oil phase reflux ratio to be 30, after stable operation, controlling the mass concentration of water in a water phase to be 95%, controlling the acid content of cyclohexane discharged at the top of the tower to be 100ppm, controlling the temperature of a tower kettle to be about 118 ℃, and controlling the mass concentration of acetic acid discharged at the tower kettle to be 99.8%.
Example 3
Step one
Under normal pressure, adding a mixture of cyclohexane with the mass fraction of 50% and acetic acid with the mass fraction of 50% from a feed inlet of a rectifying tower at the flow rate of 5kg/h, and establishing the liquid level of a tower kettle to be 60%; and adding water into the water phase area of the oil-water phase separation tank (4) to establish the liquid level of the water phase at 30-50%.
Step two
A reboiler (8) at the bottom of the tower is heated to raise the temperature, when the material is discharged from the top of the tower, a reflux pump (5) of a water phase at the top of the tower is started, the reflux flow of the water phase is adjusted to be about 0.275kg/h (the reflux flow is 11 percent of the sum of the reflux flow of the oil phase at the top of the tower and the mass flow of the discharged material), and the temperature at the top of the rectifying tower is controlled to be 69.4 ℃ of the azeotropic temperature of water and cyclohexane; gradually establishing an oil phase liquid level of 60-80% of an oil phase tank (4) at the top of the tower, not starting a reflux pump (6) of the oil phase at the top of the tower, controlling the reflux ratio of the oil phase to be 0, after stable operation, controlling the mass concentration of water in the water phase to be 98%, controlling the acid content of cyclohexane discharged at the top of the tower to be 60ppm, controlling the temperature of a tower kettle to be about 118 ℃, and controlling the mass concentration of acetic acid discharged at the tower kettle to be 99.6%.
Comparative example 1
As in example 3, under normal pressure, a mixture of cyclohexane with a mass fraction of 50% and acetic acid with a mass fraction of 50% is added at a feed inlet of a rectifying tower with a mass fraction of 5kg/h, a liquid level of a tower kettle is established to be 60%, the temperature of the tower kettle is raised, an oil phase liquid level of an oil-water phase separation tank (4) at the top of the tower is established to be 60-80%, an oil phase reflux pump (6) at the top of the tower is started, and the oil phase reflux ratio is controlled to be 1; after stable operation, the temperature at the top of the rectifying tower is 78 ℃; the acid content of cyclohexane in the oil phase at the top of the column was 16 wt%, and cyclohexane and acetic acid could not be separated.
Comparative example 2
As in example 3, under normal pressure, a mixture of 50% cyclohexane, 25% acetic acid and 25% water by mass is added at a feed inlet of a rectifying tower of 5kg/h, a liquid level of a tower kettle is established to be 60%, the temperature of the tower kettle is raised, an oil phase liquid level of an oil-water phase separation tank (4) at the top of the tower is established to be 60-80%, an oil phase reflux pump (6) at the top of the tower is started, and the oil phase reflux ratio is controlled to be 1; after stable operation, the temperature at the top of the rectifying tower is 69.4 ℃; the acid content of the cyclohexane in the oil phase at the top of the tower is 1ppm, the mass concentration of the acetic acid discharged from the bottom of the tower is 63 percent, and qualified acetic acid cannot be obtained.
As can be seen from the above examples and comparative examples, the process for separating cyclohexane and acetic acid is simple, low in energy consumption and material consumption, and suitable for industrialization.
Claims (13)
1. A method for separating cyclohexane and acetic acid is characterized in that a mixed solution of cyclohexane and acetic acid is heated and azeotroped; adding water into an azeotropic system of cyclohexane and acetic acid, and controlling the temperature of the system to be 69.4-69.6 ℃; the cyclohexane-water forms an azeotrope and is separated from the acetic acid; collecting cyclohexane-water azeotrope, cooling and separating to obtain cyclohexane.
2. A process for separating cyclohexane and acetic acid according to claim 1, wherein the initial concentration of acetic acid in the mixed solution of cyclohexane and acetic acid is 10 to 95% by mass.
3. A process for separating cyclohexane and acetic acid according to claim 1, wherein the initial concentration of acetic acid in the mixed solution of cyclohexane and acetic acid is 10 to 50% by mass.
4. The method for separating cyclohexane and acetic acid according to claim 1, wherein water obtained by cooling and separating an azeotropic system of cyclohexane and water is recycled.
5. The method for separating cyclohexane and acetic acid according to claim 1, wherein the oil phase obtained by condensation of the cyclohexane-water azeotropic system is recycled; the oil phase reflux ratio is less than or equal to 30.
6. A process for separating cyclohexane and acetic acid according to claim 1 or 5, characterized in that the mass concentration of the added water is 98-99.9%.
7. A process for separating cyclohexane and acetic acid, characterized in that the separation is carried out by means of a system comprising:
the system comprises a rectifying tower, a tower top condenser, an oil-water phase separation tank, a tower top water phase reflux pump, a tower top oil phase reflux pump and a tower bottom cooler;
the rectifying tower comprises a rectifying section and a stripping section, and the bottom of the rectifying tower is connected with a tower bottom reboiler; the rectifying tower is provided with a feed inlet, the top of the rectifying tower is provided with a cyclohexane-water azeotrope outlet, the bottom of the rectifying tower is provided with an acetic acid outlet, and the rectifying section is also provided with a reflux inlet;
the outlet of the cyclohexane-water azeotrope is connected with the azeotrope inlet of the oil-water phase-splitting tank, and the connected pipeline is provided with a tower top condenser;
the oil-water phase separation tank is also provided with a water injection port, a water outlet and an oil phase outlet; the water outlet is connected with a reflux inlet of the rectifying tower, and the oil phase outlet is connected with a cyclohexane storage tank;
the separation step comprises the following steps:
the method comprises the following steps: under normal pressure, adding a mixture of cyclohexane and acetic acid from a feed inlet of a rectifying tower, and adding water into a water phase region of an oil-water phase separation tank;
step two: heating a reboiler at the bottom of the tower to increase the temperature, starting a water phase reflux pump at the top of the tower when the material is discharged from the top of the tower, adjusting the reflux flow of the water phase, and controlling the temperature of a rectifying section of the rectifying tower to be 69.4-69.6 ℃ of the azeotropic temperature of cyclohexane and water; starting an oil phase reflux pump at the top of the tower, and controlling the oil phase reflux ratio to be less than or equal to 30;
step three: continuously extracting cyclohexane from an oil phase outlet of the oil-water phase separation tank; and (3) extracting acetic acid from an acetic acid outlet of the rectifying tower.
8. A process for the separation of cyclohexane and acetic acid according to claim 7 wherein the oil phase outlet is also connected to the reflux inlet of the rectification column.
9. A process according to claim 8, wherein the oil phase outlet is connected to the reflux inlet of the rectification column via an overhead oil phase reflux pump.
10. A process according to claim 7, wherein the acetic acid outlet of the rectification column is connected to an acetic acid storage tank, and a bottom condenser is provided in the connection line.
11. A process according to claim 7, wherein the water outlet of the aqueous oil phase separation tank is connected to the reflux inlet of the rectification column via an overhead aqueous phase reflux pump.
12. The method for separating cyclohexane and acetic acid according to claim 7, wherein the temperature of the upper part of the rectifying section of the rectifying tower is controlled to be 69.4-69.6 ℃.
13. A process according to claim 7, wherein the reflux rate of water is 9.0 to 11.0% of the sum of the reflux rate of the oil phase at the top of the column and the mass flow rate of the discharged oil phase.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710416969.0A CN108976115B (en) | 2017-06-05 | 2017-06-05 | Method and system for separating cyclohexane and acetic acid |
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