Method for separating ethanol and utilizing energy
阅读说明：本技术 分离乙醇与能量利用的方法 (Method for separating ethanol and utilizing energy ) 是由 杨卫胜 胡帅 刘银川 胡松 于 2018-08-17 设计创作，主要内容包括：本发明涉及一种分离乙醇与能量利用的方法,主要解决现有技术中1,4-二氧六环和乙醇形成共沸物分离困难问题。本发明通过采用加压精馏的技术方案,消除共沸,直接对1,4-二氧六环和乙醇混合溶液进行分离,同时采用精馏塔塔顶气相物流经过增压升温后,作为塔釜再沸器部分或者全部热源的方式,对能量进行回收利用,可用于1,4-二氧六环和乙醇的工业生产中。(The invention relates to a method for separating ethanol and utilizing energy, which mainly solves the problem that in the prior art, 1,4-dioxane and ethanol form azeotrope and are difficult to separate. The invention adopts the technical scheme of pressure rectification to eliminate azeotropy, directly separates the mixed solution of the 1,4-dioxane and the ethanol, simultaneously adopts a mode that gas phase material flow at the top of the rectifying tower is used as part or all of a heat source of a reboiler at the tower bottom after being pressurized and heated, recycles energy, and can be used in the industrial production of the 1,4-dioxane and the ethanol.)
1. A method for separating ethanol and utilizing energy is to carry out pressurized rectification separation on a mixture of 1,4-dioxane and ethanol in a pressurized rectification tower, wherein the operating conditions of the pressurized rectification tower are as follows:
the theoretical plate number is 20-100, the operation pressure of the tower top is 0.20-1.0 MPaA, and the temperature of the tower top is 90-160 ℃; the operation pressure of the tower kettle is 0.21-1.01 MPaA, and the temperature of the tower kettle is 100-200 ℃.
2. The method for utilizing the ethanol and the energy as claimed in claim 1, wherein the gas phase material flow at the top of the rectifying tower is used as part or all of the heat source of the reboiler at the tower bottom after being pressurized and heated.
3. The method for utilizing ethanol and energy as claimed in claim 1, wherein the first condensed material flow obtained after the heat exchange of the gas phase flow at the top of the rectifying tower and the reboiler at the bottom of the rectifying tower is sent into a reflux tank, two material flows are taken out from the lower part or the bottom of the reflux tank, the first material flow is used as the top product flow, and the second material flow is used as the reflux to return to the upper part of the rectifying tower.
4. The ethanol and energy utilization process of claim 1, wherein the first condensate stream is further cooled to a temperature at or below the dew point temperature prior to being sent to the reflux drum.
5. The ethanol and energy utilization method according to claim 1, wherein the ratio of 1,4-dioxane to ethanol in the mixture of 1,4-dioxane and ethanol is, by mass percent: ethanol (1: 99) to (99: 1).
6. The method for utilizing ethanol and energy according to claim 1, wherein the number of theoretical plates is 20 to 100.
7. The ethanol and energy utilization process of claim 1, wherein the overhead operating pressure is from 0.20 to 1.0 MPaA.
8. The method for utilizing ethanol and energy according to claim 1, wherein the temperature at the top of the tower is 90-160 ℃.
9. The method for utilizing ethanol and energy according to claim 1, wherein the operation pressure of the tower bottom is 0.21-1.01 MPaA.
10. The method for utilizing ethanol and energy according to claim 1, wherein the temperature of the column bottom is 100-200 ℃.
11. The method for utilizing the ethanol and the energy as claimed in claim 1, wherein the pressurization pressure of the gas phase stream at the top of the rectifying tower is 200-2500 kPa.
Technical Field
The invention relates to the field of 1,4-dioxane production, in particular to an energy-saving separation method of a 1, 4-dioxane-ethanol system.
Background
1,4-dioxane (1,4-dioxane), molecular formula C4H8O2, molecular weight 88.11, colorless liquid. Slightly fragrant. Density 1.0329, refractive index 1.4175,
The product can be used as solvent, reaction medium, and extractant in the manufacture of special fine chemicals such as medicine, cosmetic, and perfume, and in scientific research. In Japan, the product is mainly used as stabilizer of 1,1, 1-trichloroethane, and the addition amount is 2.5-4%; secondly, the polyurethane/amino acid composite leather is mostly used as a reaction solvent of polyurethane synthetic leather, amino acid synthetic leather and the like. The product has high dissolving power, similar to that of dimethyl formamide, and higher than that of tetrahydrofuran. 1,4-dioxane has the following important uses: 1. form coordination compounds with sulfur trioxide, and can be used as a sulfating agent in the synthesis of a plurality of compounds; 2. used for extracting medicines and pesticides, dewaxing petroleum products and the like; 3. as a dispersant for dyes, a dispersant for wood colorants, and a solvent for oil-soluble dyes; 4. used as a high-purity metal surface treatment agent, etc.
1,4-dioxane is readily soluble in ethanol, and 1,4-dioxane and ethanol form an azeotrope at atmospheric pressure and reduced pressure. 101.3kPa
The ethanol is commonly called alcohol, the molecular formula is C2H6O, according to GB/T394.1-2008 industrial alcohol national standard, the top grade is more than or equal to 96% vol, and the first grade is more than or equal to 95% vol; according to GB/T678-2002 anhydrous ethanol national standard, the chemical purity is more than or equal to 99.5 percent wt, and the water content is less than or equal to 0.5 percent wt; the analytical purity is more than or equal to 99.7 percent by weight, and the water content is less than or equal to 0.3 percent by weight; the top grade purity is more than or equal to 99.8 percent by weight, and the water content is less than or equal to 0.2 percent by weight; the ethanol has wide application range, and can be used for preparing acetic acid, beverages, essence, dye, fuel and the like. In medical treatment, ethanol with the volume fraction of 70-75% is also commonly used as a disinfectant and the like, and has wide application in national defense chemical industry, medical treatment and health, food industry, industrial and agricultural production.
In recent years, the consumption of fuel ethanol has increased due to fluctuations in the price of oil. The fuel ethanol industry in China starts late, but develops rapidly, and the fuel ethanol has wide prospects in China. With the further increase of domestic petroleum demand, energy supply diversification strategies represented by alternative energy sources such as ethanol have become one direction of the energy policy in China. China has become the third major biofuel ethanol producing country and country of application in the world after Brazil and the United states. Fuel ethanol has moved to the way of non-grain ethanol development and has been rapidly developed.
The fuel ethanol has the characteristics of cleanness, renewability and the like, and can reduce the emission of carbon monoxide and hydrocarbon in automobile exhaust. The key points of the fuel ethanol industry in China in the future are to reduce the production cost and reduce government subsidies, so that consumption control standards and product quality technical standards of the biofuel ethanol production process are established, and the fixed-rate standards of the fuel ethanol production consumption, including material consumption, water consumption, energy consumption and the like, are unified, so that the method is a powerful means for reducing cost and improving efficiency.
As a gasoline additive, the octane number of the gasoline can be improved. Generally, the octane number of the motor gasoline is generally required to be 90 or 93, and the octane number of ethanol can reach 111, so that the octane number of the gasoline can be greatly improved by adding fuel ethanol into the gasoline, the blending effect of the ethanol on the octane number of alkane gasoline components (alkylate and light naphtha) is better than that of olefin gasoline components (catalytic cracking gasoline) and aromatic gasoline components (catalytic reforming gasoline), and the antiknock property of the gasoline can be effectively improved by adding the ethanol.
Ethanol, which has an oxygen content of up to 34.7%, can be added to gasoline in smaller amounts than methyl tert-butyl ether (MTBE). 7.7 percent ethanol is added into the gasoline, and the oxygen content reaches 2.7 percent; if 10% ethanol is added, the oxygen content can reach 3.5%, so the ethanol is added to help the gasoline to be completely combusted, and the pollution to the atmosphere is reduced. The fuel ethanol is used for replacing tetraethyl lead as a gasoline additive, so that the pollution of lead in the air can be eliminated; and the MTBE is replaced, so that the pollution to underground water and air can be avoided. In addition, the octane number and the oxygen content of the gasoline are improved, and the ethanol can improve the quality of automobile exhaust and reduce pollution. Generally, when the addition amount of ethanol in gasoline is not more than 15%, the driving performance of the vehicle is not obviously affected, but the content of hydrocarbons, NOx and CO in tail gas is obviously reduced. Research reports on american automotive/oil (AQIRP) show: compared with the conventional gasoline, the gasoline containing 6 percent of ethanol and the new formula of California has the advantages that HC emission can be reduced by 5 percent, CO emission can be reduced by 21-28 percent, NOx emission can be reduced by 7-16 percent, and the emission of toxic gases can be reduced by 9-32 percent.
In 1943, The Ternary System, Dioxane-Ethanol-Water, reported that two of 1,4-Dioxane, Ethanol and
Simulation of azeotropic distillation of ethanol, dioxane, methanol and water, chemical industry and engineering, 2015,32 (2): 69-73, aiming at an ethanol-water system containing methanol and 1,4-dioxane, the method of adopting the flow of two azeotropic distillation towers to realize dehydration is provided, cyclohexane is selected as an entrainer, the azeotropic characteristics among the components in the system are analyzed, and the flow simulation software Aspenplus is utilized to carry out simulation calculation on the flow. The results show that the method adopting the two-tower flow can remove the water in the feed to be below 0.05 percent (mass fraction), the methanol in the feed can be discharged from the tower kettle of the recovery tower, and the simulation results are basically consistent with the actual industrial data. The article only relates to azeotropic distillation dehydration and does not relate to the separation of ethanol and 1, 4-dioxane.
CN 1473823A the invention discloses a production process of high-
Disclosure of Invention
The invention aims to solve the technical problem that azeotrope is difficult to separate between 1,4-dioxane and ethanol in the prior art, and provides a novel method for separating ethanol, which has the advantages of short process flow, less equipment investment, convenient operation, easy control, no introduction of new impurities such as an extracting agent and the like.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: performing pressurized rectification separation on a mixture of 1,4-dioxane and ethanol in a pressurized rectification tower under the operating conditions that the theoretical plate number is 20-100, the operating pressure at the top of the tower is 0.20-1.0 MPaA, and the temperature at the top of the tower is 90-160 ℃; the operation pressure of the tower kettle is 0.21-1.01 MPaA, and the temperature of the tower kettle is 100-200 ℃.
In the technical scheme of the invention, the gas phase material flow at the top of the rectifying tower is used as part or all of the heat source of the reboiler at the tower bottom after being pressurized and heated.
In the technical scheme of the invention, a first condensate flow obtained after heat exchange between a gas phase flow at the top of the rectifying tower and a reboiler at the bottom of the rectifying tower is sent into a reflux tank, two flows are collected from the lower part or the bottom of the reflux tank, the first flow is taken as a product flow at the top of the rectifying tower, and the second flow is taken as reflux and returned to the upper part of the rectifying tower.
In the technical scheme of the invention, the first condensate flow can be further cooled to the dew point temperature or below the dew point temperature before being sent to the reflux tank.
In the technical scheme of the invention, the mass percentage of the 1,4-dioxane in the mixture of the 1,4-dioxane and the ethanol is as follows: ethanol (1: 99) to (99: 1).
In the technical scheme of the invention, the number of the theoretical plates is 20-100, and preferably 30-70.
In the technical scheme of the invention, the operation pressure at the top of the rectifying tower is 0.20-1.0 MPaA, and preferably 0.20-0.8 MPaA.
In the technical scheme of the invention, the temperature of the tower top is 90-160 ℃, and preferably 90-145 ℃.
In the technical scheme of the invention, the operation pressure of the tower kettle is 0.21-1.01 MPaA, preferably 0.21-0.81 MPaA;
in the technical scheme of the invention, the temperature of the tower kettle is 100-200 ℃, and preferably 100-190 ℃.
In the technical scheme of the invention, the pressurization pressure of the gas phase material flow at the top of the rectifying tower is 200-2500 kPa, preferably 400-2000 kPa.
The inventor experimentally found that 1,4-dioxane and ethanol form an azeotrope under normal pressure and reduced pressure. The pressure is 101.3kPaA, the azeotropic composition is 1, 4-dioxane: ethanol is 5.1:94.9mole percent, and the azeotropic point temperature is 78.13 ℃; the azeotropic phenomenon disappears when the pressure exceeds 0.181 MPaA.
In the technical scheme of the invention, the gas-phase material flow at the top of the rectifying tower is used as part or all of the heat source of the reboiler at the tower bottom after being pressurized and heated, so that the steam consumption at the tower bottom can be greatly reduced, and the energy is saved. The gas-phase material flow at the top of the rectifying tower is subjected to heat exchange with a reboiler at the tower bottom to obtain a first condensate material flow, the first condensate material flow is sent into a reflux tank, two material flows are extracted from the lower part or the bottom of the reflux tank, the first material flow is used as the material flow of a product at the top of the rectifying tower, the second material flow is used as reflux and returns to the upper part of the rectifying tower, and two material flows extracted from the lower part or the bottom of the reflux tank can be pressurized.
In the technical scheme of the invention, when the gas-phase material flow at the top of the rectifying tower is pressurized and heated and is used as a part of heat source of a reboiler at the tower bottom, a common reboiler is required to be added at the tower bottom of the rectifying tower, and the common reboiler adopts external steam or other heat sources as the heat source.
The invention changes the azeotropic composition between 1,4-dioxane and ethanol by increasing the operating pressure, when reaching a certain pressure, the azeotropic composition between 1,4-dioxane and ethanol is eliminated, the 1,4-dioxane and ethanol mixed solution is directly separated, and simultaneously, the gas phase material flow at the top of the rectifying tower is pressurized and heated to be used as part or all of the heat source of the reboiler at the tower bottom, so that the energy is recycled, and the method for separating ethanol from energy is simple, efficient and energy-saving.
By adopting the technical scheme of the invention, the operation is convenient, the control is easy, no new impurity is introduced, the purity of the 1,4-dioxane product can reach 99.90 wt% or more, the purity of the absolute ethyl alcohol product can reach 99.50 wt% or more, and better technical effects are obtained.
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention in any way.
Drawings
FIG. 1 is a schematic process flow diagram of the present invention.
FIG. 2 is a schematic process flow diagram of a comparative example.
In fig. 1 and 2, 1 is a feed mixed solution, 2 is a 1,4-dioxane material flow, 3 is a rectifying tower kettle reboiler feed material flow, 4 is a rectifying tower kettle reboiler discharge material flow, 5 is a tower top gas phase material flow, 6 is a first condensate material flow, 7 is a reflux material flow, 8 is an anhydrous ethanol material flow, 10 is a pressurized material flow, 11 is a second condensate material flow, and 12 is a third condensate material flow.
T is a rectifying tower, D is a reflux tank, E1 is a condenser, E2 is a reboiler, and F is pressurizing equipment.
In the figure 1, a feed mixed solution (1) containing ethanol and 1,4-dioxane enters from the side face of a rectifying tower T, a tower bottom of the rectifying tower T extracts a 1,4-dioxane material flow (2), a tower bottom reboiler feed material flow (3) of the rectifying tower is sent into a reboiler E2 to obtain a rectifying tower reboiler discharge material flow (4) and returns to the rectifying tower T, a tower top gas phase material flow (5) is obtained at the top of the rectifying tower T, the tower top gas phase material flow (5) is sent into a supercharging device F to be supercharged and heated to obtain a supercharged material flow (10) and exchange heat with the reboiler E2 to obtain a second condensate material flow (11), the second condensate material flow (11) is continuously cooled by a condenser E1 to obtain a third condensate material flow (12) and is sent into a reflux tank D, two material flows are extracted from the lower part or the bottom part of the reflux tank D, the first material flow is used as a tower top product material flow (8), and the second material flow is returned to the upper part of.
In fig. 2, a feed mixed solution (1) containing ethanol and 1,4-dioxane enters from the side of a rectifying tower T, a tower bottom of the rectifying tower T collects a 1,4-dioxane material flow (2), a tower bottom reboiler feed material flow (3) of the rectifying tower is sent to a reboiler E2 to obtain a tower bottom reboiler discharge material flow (4) and returns to the rectifying tower T, a tower top gas phase material flow (5) is obtained at the top of the rectifying tower T, the tower top gas phase material flow (5) is cooled by a condenser E1 to obtain a first condensate material flow (6) and is sent to a reflux tank D, two material flows are collected from the lower part or the bottom of the reflux tank D, the first material flow is taken as a tower top product material flow (8), and the second material flow is taken as a reflux material flow (7) and returns to the upper part of the rectifying tower T.
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention in any way.
Detailed Description
[ example 1 ]
According to the process flow of the invention shown in figure 1, a 1, 4-dioxane-ethanol mixture continuously enters a rectifying tower, the feeding flow is 1000kg/h, and the ethanol and the 1,4-dioxane form 85% by mass: 15% and the feed temperature was 85 ℃. The theoretical plate number of the rectifying tower is 32. The operating conditions of the rectifying tower are as follows: the operation pressure at the top of the tower is 0.79MPaA, and the temperature at the top of the tower is 142 ℃; the column bottom pressure was 0.80MPaA and the column bottom temperature was 187 ℃. Ethanol with the purity of 99.99 wt% is obtained at the top of the tower, the flow rate of the ethanol is 850kg/h, 1,4-dioxane with the purity of 99.99 wt% is obtained at the bottom of the tower, and the flow rate of the 1,4-dioxane is 150 kg/h.
Gas phase material flow at the top of the rectifying tower is pressurized by 1800kPa to provide 3033kW heat source for the tower kettle, and external steam is required to provide 1993kW heat source for the tower kettle.
[ example 2 ]
According to the process flow of the invention shown in figure 1, a 1, 4-dioxane-ethanol mixture continuously enters a rectifying tower, the feeding flow is 1000kg/h, and the ethanol and the 1,4-dioxane form 85% by mass: 15% and the feed temperature was 85 ℃. The theoretical plate number of the rectifying tower is 40. The operating conditions of the rectifying tower are as follows: the operation pressure at the tower top is 0.60MPaA, and the temperature at the tower top is 132 ℃; the pressure in the column bottom was 0.61MPaA and the temperature in the column bottom was 173 ℃. Ethanol with the purity of 99.99 wt% is obtained at the top of the tower, the flow rate of the ethanol is 850kg/h, 1,4-dioxane with the purity of 99.99 wt% is obtained at the bottom of the tower, and the flow rate of the 1,4-dioxane is 150 kg/h.
The gas phase material flow at the top of the rectifying tower is pressurized by 1500kPa, a 3357kW heat source is provided for the tower kettle, and 1835kW heat source is provided for the tower kettle by external steam.
[ example 3 ]
According to the process flow of the invention shown in figure 1, a 1, 4-dioxane-ethanol mixture continuously enters a rectifying tower, the feeding flow is 1000kg/h, and the ethanol and the 1,4-dioxane form 85% by mass: 15% and the feed temperature was 85 ℃. The theoretical plate number of the rectifying tower is 55. The operating conditions of the rectifying tower are as follows: the operation pressure at the top of the tower is 0.40MPaA, and the temperature at the top of the tower is 118 ℃; the pressure in the bottom of the column was 0.41MPaA, and the temperature in the bottom of the column was 155 ℃. Ethanol with the purity of 99.98 wt% is obtained at the top of the tower, the flow rate of the ethanol is 850kg/h, 1,4-dioxane with the purity of 99.95 wt% is obtained at the bottom of the tower, and the flow rate of the 1,4-dioxane is 150 kg/h.
The gas phase material flow at the top of the rectifying tower is pressurized by 1000kPa, a 3900kW heat source is provided for the tower kettle, the tower kettle needs external steam to provide a 1496kW heat source, and by adopting the technical scheme of the invention, the steam consumption of the tower kettle is reduced by 72.28%.
[ example 4 ]
According to the process flow of the invention shown in figure 1, a 1, 4-dioxane-ethanol mixture continuously enters a rectifying tower, the feeding flow is 1000kg/h, and the ethanol and the 1,4-dioxane form 85% by mass: 15% and the feed temperature was 85 ℃. The theoretical plate number of the rectifying tower is 68. The operating conditions of the rectifying tower are as follows: the operation pressure at the top of the tower is 0.25MPaA, and the temperature at the top of the tower is 103 ℃; the pressure in the column bottom was 0.26MPaA, and the temperature in the column bottom was 128 ℃. Ethanol with the purity of 99.54 wt% is obtained at the top of the tower, the flow rate of the ethanol is 850kg/h, 1,4-dioxane with the purity of 99.90 wt% is obtained at the bottom of the tower, and the flow rate of the 1,4-dioxane is 150 kg/h.
The gas phase material flow at the top of the rectifying tower is pressurized by 450kPa, 4995kW heat source is provided for the tower kettle, 1026kW heat source is provided for the tower kettle by external steam, and the technical scheme of the invention is adopted, so that 82.96% of steam consumption at the tower kettle is reduced.
[ example 5 ]
According to the process flow of the invention shown in figure 1, a 1, 4-dioxane-ethanol mixture continuously enters a rectifying tower, the feeding flow is 1000kg/h, and the ethanol and the 1,4-dioxane form a mixture with the mass percentage of 70%: 30% and the feed temperature is 85 ℃. The theoretical plate number of the rectifying tower is 55. The operating conditions of the rectifying tower are as follows: the operation pressure at the top of the tower is 0.40MPaA, and the temperature at the top of the tower is 118 ℃; the pressure in the bottom of the column was 0.41MPaA, and the temperature in the bottom of the column was 155 ℃. Ethanol with the purity of 99.98 wt% is obtained at the top of the tower, the flow rate of the ethanol is 700kg/h, 1,4-dioxane with the purity of 99.95 wt% is obtained at the bottom of the tower, and the flow rate of the 1,4-dioxane is 300 kg/h.
The gas phase material flow at the top of the rectifying tower is pressurized by 1000kPa to provide 3877kW heat sources for the tower kettle, and the tower kettle needs external steam to provide 1487kW heat sources, so that the technical scheme of the invention is adopted to reduce the steam consumption of the tower kettle by 72.28%.
[ example 6 ]
According to the process flow of the invention shown in figure 1, a 1, 4-dioxane-ethanol mixture continuously enters a rectifying tower, the feeding flow is 1000kg/h, and the ethanol and the 1,4-dioxane form a mixture with the mass percentage of 50%: 50% and the feed temperature is 85 ℃. The theoretical plate number of the rectifying tower is 55. The operating conditions of the rectifying tower are as follows: the operation pressure at the top of the tower is 0.40MPaA, and the temperature at the top of the tower is 118 ℃; the pressure in the bottom of the column was 0.41MPaA, and the temperature in the bottom of the column was 155 ℃. Ethanol with the purity of 99.96 wt% is obtained at the top of the tower, the flow rate of the ethanol is 500kg/h, 1,4-dioxane with the purity of 99.96 wt% is obtained at the bottom of the tower, and the flow rate of the 1,4-dioxane is 500 kg/h.
The gas phase material flow at the top of the rectifying tower is pressurized by 1000kPa, a 3846kW heat source is provided for the tower kettle, the tower kettle needs external steam to provide a 1476kW heat source, and by adopting the technical scheme of the invention, the steam consumption of the tower kettle is reduced by 72.27%.
[ example 7 ]
According to the process flow shown in figure 1, a 1, 4-dioxane-ethanol mixture continuously enters a rectifying tower, the feeding flow is 1000kg/h, and the ethanol and the 1,4-dioxane form a mixture with the mass percentage of 30 percent: 70% and the feed temperature was 85 ℃. The theoretical plate number of the rectifying tower is 55. The operating conditions of the rectifying tower are as follows: the operation pressure at the top of the tower is 0.40MPaA, and the temperature at the top of the tower is 118 ℃; the pressure in the bottom of the column was 0.41MPaA, and the temperature in the bottom of the column was 155 ℃. Ethanol with the purity of 99.95 wt% is obtained at the top of the tower, the flow rate of the ethanol is 300kg/h, 1,4-dioxane with the purity of 99.98 wt% is obtained at the bottom of the tower, and the flow rate of the 1,4-dioxane is 700 kg/h.
The gas phase material flow at the top of the rectifying tower is pressurized by 1000kPa, a 3813kW heat source is provided for the tower kettle, the 1467kW heat source is provided for the tower kettle by external steam, and the steam consumption of the tower kettle is reduced by 72.22% by adopting the technical scheme of the invention.
[ example 8 ]
According to the process flow shown in figure 1, a 1, 4-dioxane-ethanol mixture continuously enters a rectifying tower, the feeding flow is 1000kg/h, and the ethanol and the 1,4-dioxane form a mixture with the mass percentage of 15 percent: 85% and the feeding temperature is 85 ℃. The theoretical plate number of the rectifying tower is 55. The operating conditions of the rectifying tower are as follows: the operation pressure at the top of the tower is 0.40MPaA, and the temperature at the top of the tower is 118 ℃; the pressure in the bottom of the column was 0.41MPaA, and the temperature in the bottom of the column was 155 ℃. Ethanol with the purity of 99.94 wt% is obtained at the top of the tower, the flow rate of the ethanol is 150kg/h, 1,4-dioxane with the purity of 99.99 wt% is obtained at the bottom of the tower, and the flow rate of the 1,4-dioxane is 850 kg/h.
The gas phase material flow at the top of the rectifying tower is pressurized by 1000kPa, a 3790kW heat source is provided for the tower kettle, 1459kW heat source is provided for the tower kettle by external steam, and by adopting the technical scheme of the invention, the steam consumption of the tower kettle is reduced by 72.20%.
[ COMPARATIVE EXAMPLE 1 ]
According to the process flow shown in fig. 2, a 1, 4-dioxane-ethanol mixture continuously enters a rectifying tower, the feeding flow is 1000kg/h, and the ethanol and the 1,4-dioxane form 85% by mass: 15% and the feed temperature was 85 ℃. The theoretical plate number of the rectifying tower is 32. The operating conditions of the rectifying tower are as follows: the operation pressure at the top of the tower is 0.79MPaA, and the temperature at the top of the tower is 142 ℃; the column bottom pressure was 0.80MPaA and the column bottom temperature was 187 ℃. The ethanol with the purity of 99.99 wt% is obtained at the top of the tower, the flow rate of the ethanol is 850kg/h, the 1,4-dioxane with the purity of 99.99 wt% is obtained at the bottom of the tower, the flow rate of the 1,4-dioxane is 150kg/h, the load of the bottom of the tower is 5026kW, and the outside steam is required to provide a 5026kW heat source at the bottom of the tower.
[ COMPARATIVE EXAMPLE 2 ]
According to the process flow shown in fig. 2, a 1, 4-dioxane-ethanol mixture continuously enters a rectifying tower, the feeding flow is 1000kg/h, and the ethanol and the 1,4-dioxane form 85% by mass: 15% and the feed temperature was 85 ℃. The theoretical plate number of the rectifying tower is 40. The operating conditions of the rectifying tower are as follows: the operation pressure at the tower top is 0.60MPaA, and the temperature at the tower top is 132 ℃; the pressure in the column bottom was 0.61MPaA and the temperature in the column bottom was 173 ℃. The ethanol with the purity of 99.99 wt% is obtained at the top of the tower, the flow rate of the ethanol is 850kg/h, the 1,4-dioxane with the purity of 99.99 wt% is obtained at the bottom of the tower, the flow rate of the 1,4-dioxane is 150kg/h, the load of the bottom of the tower is 5192kW, and the outside steam is required to provide a 5192kW heat source.
[ COMPARATIVE EXAMPLE 3 ]
According to the process flow shown in fig. 2, a 1, 4-dioxane-ethanol mixture continuously enters a rectifying tower, the feeding flow is 1000kg/h, and the ethanol and the 1,4-dioxane form 85% by mass: 15% and the feed temperature was 85 ℃. The theoretical plate number of the rectifying tower is 55. The operating conditions of the rectifying tower are as follows: the operation pressure at the top of the tower is 0.40MPaA, and the temperature at the top of the tower is 118 ℃; the pressure in the bottom of the column was 0.41MPaA, and the temperature in the bottom of the column was 155 ℃. The ethanol with the purity of 99.98 wt% is obtained at the top of the tower, the flow rate of the ethanol is 850kg/h, the 1,4-dioxane with the purity of 99.95 wt% is obtained at the bottom of the tower, the flow rate of the 1,4-dioxane is 150kg/h, the load of the bottom of the tower is 5396kW, and an external steam is needed to provide a 5396kW heat source for the bottom of the tower.
[ COMPARATIVE EXAMPLE 4 ]
According to the process flow shown in fig. 2, a 1, 4-dioxane-ethanol mixture continuously enters a rectifying tower, the feeding flow is 1000kg/h, and the ethanol and the 1,4-dioxane form 85% by mass: 15% and the feed temperature was 85 ℃. The theoretical plate number of the rectifying tower is 68. The operating conditions of the rectifying tower are as follows: the operation pressure at the top of the tower is 0.25MPaA, and the temperature at the top of the tower is 103 ℃; the pressure in the column bottom was 0.26MPaA, and the temperature in the column bottom was 128 ℃. Ethanol with the purity of 99.54 wt% is obtained at the top of the tower, the flow rate of the ethanol is 850kg/h, 1,4-dioxane with the purity of 99.90 wt% is obtained at the bottom of the tower, the flow rate of the 1,4-dioxane is 150kg/h, the load of the bottom of the tower is 6021kW, and the outside steam is required to provide a 6021kW heat source at the bottom of the tower.
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