CN112409172A - Method and system for producing ethyl acetate - Google Patents
Method and system for producing ethyl acetate Download PDFInfo
- Publication number
- CN112409172A CN112409172A CN202011305988.4A CN202011305988A CN112409172A CN 112409172 A CN112409172 A CN 112409172A CN 202011305988 A CN202011305988 A CN 202011305988A CN 112409172 A CN112409172 A CN 112409172A
- Authority
- CN
- China
- Prior art keywords
- tower
- reboiler
- esterification
- ethyl acetate
- column
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/143—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
- B01D3/322—Reboiler specifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
- B01J3/04—Pressure vessels, e.g. autoclaves
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
A method and a system for producing ethyl acetate, belonging to the field of chemical industry. The method for producing ethyl acetate comprises the following steps: the raw materials are reacted in a reaction kettle and then input from the bottom of an esterification tower. Wherein the top temperature of the esterification tower is 110-120 ℃, and the top temperature is realized by pressurizing to the pressure of 350-450 KPa; discharging from the top of the esterification tower, exchanging heat through a first reboiler, rectifying by inputting from a rectifying tower with normal pressure, and extracting a product mainly containing ethyl acetate from the bottom of the rectifying tower, wherein the temperature of the bottom of the rectifying tower is 80-85 ℃; wherein the first reboiler is connected to the rectification column to allow latent heat of the overhead discharge to be used as a heat source for the first reboiler to match the overhead temperature to that of the product comprising primarily ethyl acetate and to achieve heat coupling by heat exchange. The method can effectively control heat loss and reduce energy consumption.
Description
Technical Field
The application relates to the field of chemical industry, in particular to a method and a system for producing ethyl acetate.
Background
As a common chemical basic product, ethyl acetate is widely applied to the chemical industry.
Currently, the industrial production method of ethyl acetate comprises: esterification, acetaldehyde, alcohol dehydrogenation, ethylene acetic acid addition, and the like. Among them, the esterification method is still an important production method.
Esterification reactions require the addition of a strong acid, usually sulfuric acid. However, at high temperatures, strong acids have a strong corrosion on metal equipment and are prone to side reactions.
The purification process after esterification generally takes two or more towers. The energy consumption is large, the unit consumption of steam for producing the finished product of the ethyl acetate by the conventional industrial process is about 1.5-2 t/t, namely the unit consumption of steam for producing one ton of ethyl acetate is 1.5-2 tons. In addition, a large amount of VOC waste gas is easily generated in the production process, and the conditions of catalyst pyrolysis and the like can also occur.
Disclosure of Invention
Based on the above-mentioned shortcomings, the present application provides a method and a system for producing ethyl acetate, so as to partially or completely improve and even solve the problem of high energy consumption in the production of ethyl acetate in the related art.
The application is realized as follows:
in a first aspect, examples of the present application provide a method of producing ethyl acetate, comprising:
the raw materials react in a reaction kettle and then are input from the bottom of an esterification tower; and the tower top temperature of the esterification tower is 110-120 ℃; the top temperature of the esterification column is achieved by pressurizing to a pressure of 350KPa to 450 KPa;
discharging from the top of the esterification tower, exchanging heat through a first reboiler, rectifying by inputting from a rectifying tower at normal pressure, and extracting a product mainly containing ethyl acetate from the bottom of the rectifying tower, wherein the temperature of the bottom of the rectifying tower is 80-85 ℃;
wherein the first reboiler is connected to the rectification column to allow latent heat of the overhead discharge to be used as a heat source for the first reboiler to match the overhead temperature to that of the product comprising primarily ethyl acetate and to achieve heat coupling by heat exchange.
The esterification tower is pressurized to operate, and the rectifying tower is operated under normal pressure, so that the latent heat of the steam at the top of the esterification tower can be utilized to heat the material of a reboiler of the rectifying tower, and the heat coupling in the system is realized. The operating pressure of the esterification tower is controlled, so that the top temperature of the esterification tower is accurately matched with the bottom temperature of the rectification tower, the heat transfer power of a reboiler is enhanced, the heat transfer efficiency is improved, the heat loss of equipment is reduced, and meanwhile, the pyrolysis of a catalyst is avoided, so that the energy consumption of the process can be obviously reduced.
According to some examples of the application, a method comprises:
the top discharge is subjected to phase separation treatment through a first phase separator after heat exchange in a first reboiler.
Optionally, the bottom material of the esterification tower and the heat exchanged in the second reboiler flow back to the reaction kettle to heat the material containing the raw material.
Optionally, the method comprises: and after the tower top discharge is subjected to heat exchange in the first reboiler, and before the tower top discharge is subjected to phase separation treatment through the first phase separator, the tower top discharge is subjected to heat exchange through a third reboiler.
Optionally, the first phase separator produces an aqueous phase and a first portion of an oil phase and a second portion of an oil phase by condensing the phases; wherein the water phase is recovered, a first part of the oil phase flows back from the top of the esterification tower, and a second part of the oil phase enters the rectifying tower from the tower as a feed material flow.
According to some examples of the application, the tower discharge of the rectifying tower is subjected to condensation phase separation through a second phase separator, wherein the water phase is recovered, and the oil phase is refluxed from the tower into the rectifying tower; and/or the tower top discharge of the rectifying tower flows back from the tower top through the condensing heat exchanger of the rectifying tower.
According to some examples of the application, a method comprises:
the top discharge of the esterification tower is subjected to heat exchange through a first reboiler and then subjected to flash evaporation through a flash tank, the top discharge of the flash tank is subjected to heat exchange through a third reboiler and then input to a first phase separator, wherein the third reboiler is connected with the bottom of the recovery tower, so that the latent heat of the top discharge of the flash tank is allowed to serve as a heat source of the third reboiler, and the top discharge of the flash tank and the bottom discharge of the recovery tower are subjected to heat exchange to achieve heat coupling;
and/or after the top discharge of the esterification tower is subjected to heat exchange by a first reboiler, the top discharge is subjected to flash evaporation by a flash tank, the bottom discharge of the flash tank is input into a first phase separator, and water phases generated by the first phase separator and a second phase separator are input into a recovery tower from the tower;
and/or the tower top discharge of the recovery tower is refluxed from the tower top after heat exchange through a condensation heat exchanger of the recovery tower.
According to some examples of the present application, the feedstock comprises primarily ethanol, acetic acid, and a catalyst, wherein the catalyst is an acidic reagent that catalyzes an esterification reaction, the acidic reagent comprising one or a combination of two or more of sulfuric acid, p-toluenesulfonic acid, and/or methanesulfonic acid.
Alternatively, the molar ratio of ethanol to acetic acid in the feedstock is from 1:1 to 1.2: 1.
Alternatively, the contents of the reaction vessel are composed of acetic acid 58 to 78 wt%, water 5 to 18 wt%, ethyl acetate 5 to 18 wt%, ethanol 0.2 to 2 wt%.
Alternatively, the top material of the esterification tower consists of 82 to 86 weight percent of ethyl acetate, 10 to 15 weight percent of water, 1 to 3 weight percent of ethanol and 0.0014 to 0.0035 weight percent of acetic acid.
According to some examples of the present application, the temperature of the reaction tank is 150 to 170 ℃, the overhead temperature of the esterification column is 110 to 120 ℃, the temperature of the tank in the rectification column is 80 to 85 ℃, the overhead temperature of the rectification column is 59 to 64 ℃, and the temperature in the rectification column is 68 to 74 ℃.
According to some examples of the present application, the overhead volumetric reflux ratio of the esterification column is 1.1 to 1.4, the volumetric reflux ratio in the column of the rectification column is oil phase total reflux, and the overhead volumetric reflux ratio of the rectification column is total reflux.
According to some examples of the present application, the ethyl acetate is more than 99.5% pure, with <40ppm acetic acid, less than 50ppm water, and less than 10ppm alcohol.
In a second aspect, examples of the present application provide a system for producing ethyl acetate, comprising:
a second reboiler;
the first processing unit is provided with a reaction kettle and an esterification tower which are matched with each other, the tower bottom of the esterification tower is connected with a second reboiler, the second reboiler is also connected with the reaction kettle, and the kettle top of the reaction kettle is also connected with the tower bottom of the esterification tower;
the second treatment unit is provided with a rectifying tower and a first peripheral treatment sub-unit, and the first peripheral treatment sub-unit is provided with a first reboiler, a third reboiler, a rectifying tower condensation heat exchanger, a first phase separator and a second phase separator;
wherein, the top of the tower of esterifying tower is connected with the bottom of the rectifying column through a first reboiler, a first reboiler is connected with a first phase splitter through a third reboiler, the first phase splitter is connected with the top of the tower of esterifying tower and the tower of the esterifying tower, a condensing heat exchanger of the rectifying column is connected with the top of the rectifying column, and a second phase splitter is connected with the tower of the rectifying column.
According to some examples of the application, the system further comprises: a recovery column and a second peripheral processing sub-unit having a flash tank and a recovery column condensing heat exchanger;
the first reboiler is connected with the third reboiler through the flash tank, the third reboiler is connected with the bottom of the recovery tower, the flash tank is further connected with the first phase splitter, and the condensation heat exchanger of the recovery tower is connected with the top of the recovery tower.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the prior art of the present application, the drawings used in the description of the embodiments or the prior art will be briefly described below.
Fig. 1 is a schematic structural diagram of a system for producing ethyl acetate in an example of the present application;
FIG. 2 is a schematic diagram of another system for producing ethyl acetate in an example of the present application;
FIG. 3 is an azeotropic phase diagram of ethyl acetate and water.
Icon: 101-a second reboiler; 102-a reaction kettle; 103-an esterification column; 104-a first phase splitter; 105-a first reboiler; 106-a third reboiler; 107-a rectification column; 108-a second phase splitter; 109-rectifying tower condensing heat exchanger; 200-a flash tank; 201-a recovery column; 202-recovery column condensing heat exchanger.
Detailed Description
Embodiments of the present application will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present application and should not be construed as limiting the scope of the present application. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The following is a detailed description of a method and system for producing ethyl acetate according to embodiments of the present application:
as an important ethyl acetate production method, the esterification method has higher energy consumption. For example, the unit consumption of steam for producing ethyl acetate finished products by the conventional industrial process (two atmospheric towers) is about 1.5-2 t/t.
The esterification method generally uses acetic acid, ethanol as raw materials for the esterification reaction, and uses strong acid (such as sulfuric acid) as a catalyst. The esterification process involves high temperatures and can cause corrosion of equipment due to the use of acids.
In order to effectively reduce heat loss, the present example proposes a system for producing ethyl acetate, which is structured as shown in fig. 1 (wherein valves for respective fluid-carrying pipes are not depicted).
The system mainly comprises a reaction kettle 102, an esterification tower 103 and a rectifying tower 107.
Thus, the production process of ethyl acetate is substantially the following: the raw materials are subjected to esterification reaction in a reaction kettle 102, then enter an esterification tower 103 for removing heavy components, and then enter a rectifying tower 107 for removing light components, so that a finished product of ethyl acetate can be obtained from the rectifying tower.
In the examples, the specific production scheme of ethyl acetate is described in detail below.
The top discharge of the reaction vessel 102 enters the esterification column 103 from the bottom side of the esterification column 103, and is subjected to component separation (heavy component removal) therein.
The bottom of the reaction vessel 102 has a valve (not shown), which is a long-closed valve.
After materials in the reaction kettle enter the esterification tower, the discharging of the esterification tower mainly comprises two parts, wherein one part of the discharging is refluxed in the form of tower bottom discharging to heat and gasify raw materials so as to facilitate the esterification reaction. As an implementation of reflux, esterification column 103 can be equipped with a second reboiler 101, both for convenience to facilitate reaction and fluid transfer. Therefore, the raw material and the bottom discharge from the esterification column 103 can be vaporized together by heat exchange in the second reboiler 101, and then introduced into the reaction tank 102. In this reaction vessel 102, an esterification reaction takes place, in which the ethyl acetate formed by the reaction forms an azeotrope with water and can then enter the esterification column 103 from the bottom.
The other part of the output from the esterification column 103, the overhead output from the esterification column 103 (crude product, mainly ethyl acetate and water, containing a small amount of ethanol), is subjected to heat exchange by the first reboiler 105, optionally after suitable work-up (e.g. further heat exchange, phase separation, as will be described in more detail later), and is fed to a rectification column 107 for further separation of components (light ends removal).
In the above-mentioned treatment step of the top discharge of the esterification tower 103, the heat exchange is realized by heat exchange between the bottom discharge of the rectification tower and the top discharge of the esterification tower. That is, the top material of the esterification column 103 exchanges heat with the bottom material/bottom discharge of the rectification column 107 via the first reboiler 105. Therefore, the heat coupling in the process system can be realized by heating the part of the bottom discharge of the rectifying tower 107 by the latent heat of the overhead vapor of the esterification tower 103 through the first reboiler 105, and the rest of the bottom discharge of the rectifying tower 107 is discharged out of the system as a finished product.
Wherein the first reboiler 105 is used as a device for utilizing heat energy, the top discharge of the esterification tower 103 can exchange heat with the bottom discharge of the rectification tower 107 in the first reboiler 105. The top discharge of the esterification tower after heat exchange can be subjected to the post-treatment. Specifically, after heat exchange, the top discharge of the esterification tower is subjected to heat exchange and temperature reduction through a third reboiler 106 so as to be condensed, and then phase separation is performed through a first phase separator 104.
In the present example, the third reboiler 106 is provided because: the energy (e.g. 5987kW calculated below) released by the total condensation of the vapor at the top of the esterification column 103 is higher than the energy (e.g. 5299kW calculated below) required for the partial gasification by heat exchange in the discharge at the bottom of the rectification column 107, so that a heat exchanger (a third reboiler 106) is further provided in addition to the first reboiler 105 to ensure the complete condensation and cooling of the gas phase discharged from the top of the esterification column 103, thereby facilitating the phase separation by the first phase separator 104.
The water phase is recovered through the first phase separator 104, part of the oil phase enters the rectifying tower 107 from the rectifying tower 107 for rectification, and the rest of the oil phase can circularly flow into the esterifying tower 103 from the top of the esterifying tower.
The material entering the rectifying tower from the first phase separator is separated, then the side stream discharged from the middle tower of the rectifying tower 107 is subjected to phase separation treatment by the second phase separator 108, the water phase is recovered, and the oil phase circularly flows back into the rectifying tower 107 from the tower of the rectifying tower 107. Meanwhile, the top discharge of the rectifying tower 107 is subjected to heat exchange by a rectifying tower condensing heat exchanger 109, and then refluxed from the top of the rectifying tower 107. While the bottom discharge of the rectification column is partly used for heat exchange with the top discharge of the esterification column 103 via the first reboiler 105.
By utilizing the ethyl acetate production system and combining the selection of process parameters and conditions, the heat energy utilization rate can be effectively improved, and the energy consumption for producing ethyl acetate is reduced. In particular, the working pressure of the esterification column and the rectification column and the temperature difference between the two, which is formed by the pressure difference, are significantly advantageous for avoiding the loss of heat energy.
In the present example, the production raw materials of the production system are ethanol, acetic acid and a catalyst. The catalyst is an acidic catalyst, and can be one or a combination of more than two of sulfuric acid, p-toluenesulfonic acid (PTSA) and/or methanesulfonic acid. Such as sulfuric acid in combination with p-toluenesulfonic acid; alternatively, a mixture of p-toluenesulfonic acid and methanesulfonic acid; alternatively, a mixture of sulfuric acid, p-toluenesulfonic acid and methanesulfonic acid. Wherein, the ethanol and the acetic acid are fed according to the molar ratio of 1:1 to 1.2:1, or the molar ratio can also be 1.05:1 to 1.2:1, namely the ethanol is in proper excess.
In the continuous production process of the production system, the stable components of the materials in the reaction kettle 102 mainly comprise 58-78 wt% of acetic acid, 5-18 wt% of water, 5-18 wt% of ethyl acetate and 0.2-2 wt% of ethanol. The stable composition of the top material of the esterification tower 103 is 82 to 86 weight percent of ethyl acetate, 10 to 15 weight percent of water, 1 to 3 weight percent of ethanol and 0.0014 to 0.0035 weight percent of acetic acid. In some specific examples, the composition of the top material of esterification column 103 is 84.6 wt%, water 13.998 wt%, ethanol 2 wt%, and acetic acid 0.002 wt%.
The production of ethyl acetate is carried out by the production system, and a finished product of high-purity ethyl acetate (the purity can reach more than 99.5%) can be obtained, wherein the content of acetic acid is less than 40ppm, the content of water is less than 50ppm, and the content of alcohol is less than 10 ppm.
If the unit consumption of steam for producing each ton of ethyl acetate is 1.50 tons, the unit consumption of steam for producing each ton of ethyl acetate can be reduced to 0.83 tons by using the production process, so that the energy consumption can be saved by more than 45%. Wherein "steam consumption" refers to the mass of steam consumed to produce 1 ton of finished ethyl acetate.
In particular, with respect to the production system described above, as previously described, the pressure of the esterification column 103 is selectively controlled so as to regulate the temperature of the esterification column overhead (and in essence, the temperature of the esterification column bottoms is also controlled so that, for example, catalyst decomposition due to excessive bottoms temperatures can be avoided), and is matched to the temperature of the rectification column 107 bottoms to take full advantage of the latent heat of the esterification column 103 overhead. In the example, the pressure of the esterification column 103 is controlled to be 350KPa to 450KPa (absolute pressure), preferably 400KPa is selected. Meanwhile, the pressure of the rectifying tower 107 is controlled to be normal pressure. In this application, pressurized refers to greater than standard atmospheric pressure.
Wherein the temperature of the reaction kettle 102 is 150 ℃ to 170 ℃ (or further 160 ℃ to 170 ℃), and the working temperature of the material entering the esterification tower 103 from the reaction kettle 102 is adjusted by controlling the pressure of the esterification tower 103.
In the present application, the esterification column 103 is controlled to have a column top temperature of 110 ℃ to 120 ℃ (or further selected from 115 ℃ to 117 ℃) by pressure control. The temperature of the bottom of the rectifying tower 107 is 80 ℃ to 85 ℃ (or further 80 ℃ to 82 ℃) by pressure control, the temperature of the top of the rectifying tower 107 is 59 ℃ to 64 ℃ (or further 59 ℃ to 62 ℃) by pressure control, and the temperature in the rectifying tower 107 is 68 ℃ to 74 ℃ (or further 69 ℃ to 73 ℃).
In the process, in order to improve the separation effect, material recycling and heat energy utilization, the reflux ratio of each device can be selectively controlled. For example, the overhead reflux ratio (volume) of esterification column 103 can be 1.1 to 1.4; the reflux ratio in the column of the rectifying column 107 is oil phase total reflux; the reflux ratio at the top of the rectifying column 107 was total reflux.
Further, as an improvement, the production system can be adjusted to improve the energy utilization rate. For example, the production system is further equipped with a recovery tower 201 (which may be operated under reduced pressure) and other corresponding peripheral devices (such as a flash drum 200, a recovery tower condensing heat exchanger 202, etc.), and the structure of the recovery tower is shown in fig. 2. Accordingly, the production process of the new production system can also be suitably adjusted compared to the process implemented by the production system of fig. 1.
Wherein, the overhead material of the esterification tower 103 is input into the flash drum 200 after being subjected to heat recovery by a first reboiler 105 (or called a rectifying tower reboiler), and part of the discharge material (such as the top of the flash drum 200) passes through a third reboiler 106 and then enters the first phase separator 104 together with the rest discharge material (such as the bottom of the flash drum 200).
The first phase separator 104 performs phase separation treatment to generate recovered water, and the recovered water generated by the first phase separator 104 and the recovered water generated by the second phase separator 108 are fed from the column of the recovery column 201 to the recovery column 201.
Similarly to the system of fig. 1, in the system of fig. 2, part of the oil phase produced by the first phase separator 104 is refluxed to the top of the esterification column 103, and the remaining part of the oil phase enters the column of the rectification column 107. And the top discharge of the recovery tower 201 is totally refluxed and enters from the top of the tower through a condensation heat exchanger 202 of the recovery tower.
The bottom discharge of the recovery tower 201 is liquid phase, and 99.9% of the liquid phase is water, wherein part of the effluent can flow back to the recovery tower 201 from the bottom side line of the recovery tower after heat exchange by the third reboiler 106, and the rest of the effluent can be directly extracted out of the system for storage.
In the present application, the pressure of esterification column 103 is adjusted so that the temperature at the top of esterification column 103 matches the temperature at the bottom of rectification column 107 (forming a suitable temperature difference to provide a driving force), thereby allowing the temperature at the top of esterification column 103 to be more fully and efficiently transferred to the bottom of rectification column 107.
In the example, the working pressure of the esterification tower 103 is 350KPa to 450 KPa. The reason for selecting this condition is that:
referring to the azeotropic phase diagram of ethyl acetate and WATER at different mass ratios shown in fig. 3, the azeotropic temperature of Ethyl Acetate (EA) and WATER (WATER) at 400kPa is 115 ℃ to 116 ℃, and the azeotropic composition is about 87 wt% EA content and 13 wt% WATER content. From the stable composition of the overhead material of the esterification column 103 (ethyl acetate 82 to 86 wt%, water 10 to 15 wt%, ethanol 1 to 3 wt%, acetic acid 0.0014 to 0.0035 wt%), the overhead temperature of the esterification column 103 can be calculated to be 115 ℃.
Under such conditions, the pressure applied to the rectifying column 107 is normal pressure (for example, 100 kPa). The majority of the ethyl acetate entering the rectification column 107 is ethyl acetate and the ethyl acetate is discharged at the bottom of the rectification column 107. There is a pressure drop of several kPa at the bottom of the rectification column 107, and therefore the temperature at the bottom of the rectification column 107 is slightly higher than the atmospheric boiling point of ethyl acetate, about 80-82 ℃. In consideration of the heat transfer coefficient, heat loss and steam saturation of the apparatus, the tower bottom material of the rectifying column 107 is heated by using the tower top steam of the esterification column 103 at 115 ℃ (the temperature difference (115 ℃ -82 ℃) is 33 ℃), which has an ideal effect.
This is based on the consideration that:
1. the reboiler is usually in a shell structure, which has low heat transfer efficiency and needs to increase temperature difference for improvement.
2. The reboiler is pressurized on one side and the media in the production system of the present application contains trace amounts of acetic acid (corrosive), so the heat exchange wall thickness of the reboiler is typically designed to be relatively thick, and the temperature is also increased to improve the heat transfer power.
In addition, the temperature of the bottom of the esterification column 103 is about 160 ℃ to 170 ℃ at an operating pressure of 400kPa, at which the catalyst is not decomposed and the catalytic speed is increased. If the pressure is further increased excessively, the temperature at the bottom of the esterification column 103 becomes too high, and a part of the catalyst (e.g., PTSA) is decomposed, so that the carbonization of the material is remarkably increased.
Also, when the operating pressure of esterification column 103 is not high enough (e.g., less than 350KPa), it can result in a decrease in the vapor temperature at the top of esterification column 103. In this case, if the distillation column 107 is operated at normal pressure, the difference in the temperature of the reboiler (first reboiler 105) becomes small, and the heat exchange area of the reboiler is greatly increased. On the one hand, the investment cost is increased, and on the other hand, the heat loss of the equipment is increased due to the increase of the heat exchange area, so that the energy conservation is not facilitated.
If one chooses not to increase the heat exchange surface of the reboiler while providing sufficient temperature to maintain the driving force, it is desirable to reduce the pressure, i.e., evacuate, the rectifier 107 (for vacuum rectification). However, since low boiling substances (e.g., methyl acetate and olefins) are present at the top of the rectifying column 107, these low boiling substances have a low boiling point and high volatility. After the distillation column 107 is evacuated, if a cooling medium having a sufficiently low temperature is not used to exchange heat, a large amount of VOC exhaust gas is generated. Meanwhile, if the low-temperature cooling medium is used, the energy consumption is greatly improved, and meanwhile, the vacuum pump also can obviously improve the power consumption of the device, so that the aim of reducing the overall energy consumption of the process system cannot be fulfilled.
Further, when the pressure of the esterification tower 103 is 300KPa, the bottom temperature of the esterification tower 103 is approximately 140 deg.C, and the top temperature of the esterification tower 103 is approximately 105 deg.C. Therefore, the temperature difference between the top temperature of the esterification column 103 and the bottom temperature of the atmospheric distillation column 107 was 23 ℃.
When the pressure of the esterification column 103 was reduced to 200kPa, the temperature at the bottom of the esterification column 103 was about 133 ℃ and the temperature at the top of the esterification column 103 was 96 ℃. Therefore, the temperature difference between the top temperature of the esterification column 103 and the bottom temperature of the atmospheric distillation column 107 is 14 ℃.
Obviously, when the pressure of the esterification tower 103 is 300kPa and 200kPa, the relative temperature difference between the esterification tower 103 and the rectification tower 107 is insufficient, so that the heat exchange area of the second reboiler 101 needs to be increased, and the heat loss is increased correspondingly.
The evaporation capacity of the esterification column 103 was about 52.3t/h, and the energy released by the condensation of the overhead vapour of the esterification column 103 from the vapour at 115 ℃ (400kPa) to liquid (400kPa) was about 5987kW, calculated for an ethyl acetate production plant with a capacity of 12.5 t/h. The evaporation capacity of the corresponding rectifying tower 107 is about 52.5t/h, and the heating energy is 5299 kW. Therefore, the latent heat energy of the overhead vapor of the esterification tower 103 is well matched with the energy required for heating the bottom material of the rectification tower 107.
In addition, after the tower top steam of the esterification tower 103 exchanges heat with the tower bottom discharge of the rectifying tower 107, surplus energy is also available, and the surplus energy can be used for carrying out coupling heat exchange with the recovery tower 201 to save energy. Specifically, after 400kPa of condensed liquid (and some uncondensed) passes through the flash tank 200, 4150kg (300kPa) of steam (to be used for heat-coupling exchange with the recovery column 201) having a temperature of 104 ℃ is produced at the top of the flash tank 200, while 45576kg (300kPa) of liquid having a temperature of 104 ℃ is produced at the bottom of the flash tank 200.
The feed rate of the recovery tower 201 is 8t/h, the energy consumption for recovering the organic matter dissolved in the water phase is about 600kW, and the top of the flash tank 200 is used for extracting 4150kg of steam, which just can provide enough energy. Meanwhile, the pressure of the recovery tower 201 can be reduced to increase the heat transfer power, the pressure is 70kPa, the bottom temperature of the recovery tower 201 is about 90 ℃, and the temperature difference is 25 ℃.
In order to increase the heat transfer temperature difference, the recovery tower 201 may or may not be depressurized, because the energy difference between the esterification tower 103 and the rectification tower 107 (such as 5987kw-5299kw) has surplus enough energy to be used as waste heat.
Therefore, in combination with the above production system, there is substantially no energy consumption in the rectification column 107 and the recovery column 201 in the production of ethyl acetate. If the unit consumption of steam per ton of ethyl acetate production is 1.50t, the unit consumption of steam can be reduced to 0.83t by using the pressurizing process, and compared with the original energy consumption (the conventional normal-pressure two-tower process), the consumption is saved by more than 45%.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A process for producing ethyl acetate, comprising:
raw materials react in a pressurized reaction kettle, and then are input from the bottom of an esterification tower, the temperature of the top of the esterification tower is 110-120 ℃, and the temperature of the top of the esterification tower is realized by pressurizing to the pressure of 350-450 KPa;
discharging from the top of the esterification tower, exchanging heat through a first reboiler, rectifying by inputting from a rectifying tower at normal pressure, and extracting a product mainly containing ethyl acetate from the bottom of the rectifying tower, wherein the temperature of the bottom of the rectifying tower is 80-85 ℃;
wherein the first reboiler is connected to the rectification column to allow latent heat of the overhead discharge of the esterification column to be used as a heat source for the first reboiler, match the overhead temperature of the esterification column to the temperature of the product comprising primarily ethyl acetate, and achieve heat coupling by heat exchange.
2. The process for producing ethyl acetate according to claim 1, characterized in that it comprises:
the material discharged from the bottom of the esterification tower exchanges heat with the raw material in a second reboiler and then reflows to the reaction kettle together so as to heat the material containing the raw material;
optionally, the top discharge of the esterification tower is subjected to phase separation treatment through a first phase separator after heat exchange in the first reboiler;
optionally, the overhead output is subjected to heat exchange by a third reboiler after the heat exchange by the first reboiler and before being subjected to phase separation by the first phase separator;
optionally, the first phase separator produces an aqueous phase and a first portion of an oil phase and a second portion of an oil phase by condensing the phases; wherein the aqueous phase is recovered, said first portion of the oil phase is refluxed from the top of the esterification column, and said second portion of the oil phase is fed as a feed stream from the column to the rectification column.
3. The method for producing the ethyl acetate according to the claim 2, characterized in that the tower discharge of the rectifying tower is subjected to condensation phase separation through a second phase separator, wherein the water phase is recovered, and the oil phase is refluxed into the rectifying tower from the tower;
and/or the tower top discharge of the rectifying tower flows back from the tower top through a rectifying tower condensation heat exchanger.
4. A process for producing ethyl acetate as claimed in claim 3, characterized in that it comprises:
the top discharge of the esterification tower is subjected to heat exchange through a first reboiler and then subjected to flash evaporation through a flash tank, the top discharge of the flash tank is subjected to heat exchange through a third reboiler and then enters a first phase separator, wherein the third reboiler is connected with the bottom of the recovery tower, so that the latent heat of the top discharge of the flash tank is allowed to serve as a heat source of the third reboiler, and the top discharge of the flash tank and the bottom discharge of the recovery tower are subjected to heat exchange to achieve heat coupling;
and/or after the top discharge of the esterification tower is subjected to heat exchange by a first reboiler, the top discharge is subjected to flash evaporation by a flash tank, the bottom discharge of the flash tank is input into a first phase separator, and the water phase generated by the first phase separator and the second phase separator is input into a recovery tower from the tower;
and/or the tower top discharge of the recovery tower is refluxed from the tower top after being subjected to heat exchange through a condensation heat exchanger of the recovery tower.
5. The method for producing ethyl acetate according to any one of claims 1 to 4, wherein the raw material mainly comprises ethanol, acetic acid and a catalyst, wherein the catalyst is an acidic reagent for catalyzing esterification, and the acidic reagent comprises one or more of sulfuric acid, p-toluenesulfonic acid and/or methanesulfonic acid;
alternatively, the molar ratio of ethanol to acetic acid in the feedstock is from 1:1 to 1.2: 1;
optionally, the contents of the reaction vessel are composed of acetic acid 58 to 78 wt%, water 5 to 18 wt%, ethyl acetate 5 to 18 wt%, ethanol 0.2 to 2 wt%;
alternatively, the top material of the esterification tower comprises 82 to 86 weight percent of ethyl acetate, 10 to 15 weight percent of water, 1 to 3 weight percent of ethanol and 0.0014 to 0.0035 weight percent of acetic acid.
6. The method for producing ethyl acetate according to claim 5, characterized in that the temperature of the reaction tank is 150 to 170 ℃, the temperature of the top of the esterification column is 110 to 120 ℃, the temperature of the bottom of the rectification column is 80 to 85 ℃, the temperature of the top of the rectification column is 59 to 64 ℃, and the temperature in the rectification column is 68 to 74 ℃.
7. The method for producing ethyl acetate according to claim 5, characterized in that the overhead volume reflux ratio of the esterification tower is 1.1 to 1.4, the in-tower volume reflux ratio of the rectification tower is total reflux of the oil phase, and the overhead volume reflux ratio of the rectification tower is total reflux.
8. The process for producing ethyl acetate according to claim 1, wherein the ethyl acetate has a purity of 99.5% or more, and contains acetic acid <40ppm, water < 50ppm, and alcohol < 10 ppm.
9. A system for producing ethyl acetate, comprising:
a second reboiler;
the first treatment unit is provided with a reaction kettle and an esterification tower which are matched with each other, the bottom of the esterification tower is connected with a second reboiler, the second reboiler is also connected with the reaction kettle, and the top of the reaction kettle is also connected with the bottom of the esterification tower;
a second treatment unit having a rectification column and a first peripheral treatment sub-unit having a first reboiler, a third reboiler, a rectification column condensing heat exchanger, a first phase separator, and a second phase separator;
the top of the esterification tower is connected with the bottom of the rectification tower through the first reboiler, the first reboiler is connected with the first phase separator through the third reboiler, the first phase separator is further connected with the top of the esterification tower and the middle of the esterification tower, the condensation heat exchanger of the rectification tower is connected with the top of the rectification tower, and the second phase separator is connected with the middle of the rectification tower.
10. The system for producing ethyl acetate according to claim 9, further comprising: a recovery column and a second peripheral processing sub-unit having a flash tank and a recovery column condensing heat exchanger;
the first reboiler is connected with the third reboiler through the flash tank, the third reboiler is connected with the bottom of the recovery tower, the flash tank is further connected with the first phase splitter, and the condensation heat exchanger of the recovery tower is connected with the top of the recovery tower.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011305988.4A CN112409172B (en) | 2020-11-19 | 2020-11-19 | Method and system for producing ethyl acetate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011305988.4A CN112409172B (en) | 2020-11-19 | 2020-11-19 | Method and system for producing ethyl acetate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112409172A true CN112409172A (en) | 2021-02-26 |
| CN112409172B CN112409172B (en) | 2023-04-07 |
Family
ID=74774653
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011305988.4A Active CN112409172B (en) | 2020-11-19 | 2020-11-19 | Method and system for producing ethyl acetate |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112409172B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113082757A (en) * | 2021-05-12 | 2021-07-09 | 重庆市中润化学有限公司 | NMP (N-methyl pyrrolidone) rectifying device |
| CN114751822A (en) * | 2022-03-16 | 2022-07-15 | 浙江建业化工股份有限公司 | Device for producing n-propyl acetate through thermal coupling and production method thereof |
| CN114917604A (en) * | 2022-05-19 | 2022-08-19 | 北京航天石化技术装备工程有限公司 | System and method for extracting acetophenone from household garbage pyrolysis tar |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101735045A (en) * | 2009-12-18 | 2010-06-16 | 中山大学 | Method for producing ethyl acetate by using entrainer |
| CN102070445A (en) * | 2011-01-13 | 2011-05-25 | 蓝仁水 | Purification method of ethyl acetate |
| CN102690197A (en) * | 2012-05-29 | 2012-09-26 | 江门谦信化工发展有限公司 | Method for preparing acetic acid mixed butyl ester by continuous reaction and rectification |
| CN103242158A (en) * | 2013-05-24 | 2013-08-14 | 中国石油大学(华东) | Technological method for synthesizing ethyl acetate |
| CN103739486A (en) * | 2013-11-26 | 2014-04-23 | 泰兴金江化学工业有限公司 | Production method for ethyl acetate crude product |
| CN104513159A (en) * | 2014-11-28 | 2015-04-15 | 江门天诚溶剂制品有限公司 | Butyl acetate energy saving production method |
| CN105017019A (en) * | 2015-07-08 | 2015-11-04 | 常州大学 | Energy-saving method for preparing isopropyl acetate |
| CN106146303A (en) * | 2016-07-26 | 2016-11-23 | 江门谦信化工发展有限公司 | A kind of acetic acid mixes continuous process system and the method for butyl ester |
| CN107954866A (en) * | 2017-12-13 | 2018-04-24 | 中国石油大学(华东) | The method and its device of differential pressure heat coupled reaction rectifying synthesis of acetic acid isopropyl ester |
| CN110437064A (en) * | 2019-07-24 | 2019-11-12 | 江门谦信化工发展有限公司 | A kind of differential pressure type energy-saving processing technique of ethyl acetate |
| CN110963913A (en) * | 2018-09-05 | 2020-04-07 | 泰兴市洁源环保工程有限公司 | Ethyl acetate production process |
-
2020
- 2020-11-19 CN CN202011305988.4A patent/CN112409172B/en active Active
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101735045A (en) * | 2009-12-18 | 2010-06-16 | 中山大学 | Method for producing ethyl acetate by using entrainer |
| CN102070445A (en) * | 2011-01-13 | 2011-05-25 | 蓝仁水 | Purification method of ethyl acetate |
| CN102690197A (en) * | 2012-05-29 | 2012-09-26 | 江门谦信化工发展有限公司 | Method for preparing acetic acid mixed butyl ester by continuous reaction and rectification |
| CN103242158A (en) * | 2013-05-24 | 2013-08-14 | 中国石油大学(华东) | Technological method for synthesizing ethyl acetate |
| CN103739486A (en) * | 2013-11-26 | 2014-04-23 | 泰兴金江化学工业有限公司 | Production method for ethyl acetate crude product |
| CN104513159A (en) * | 2014-11-28 | 2015-04-15 | 江门天诚溶剂制品有限公司 | Butyl acetate energy saving production method |
| CN105017019A (en) * | 2015-07-08 | 2015-11-04 | 常州大学 | Energy-saving method for preparing isopropyl acetate |
| CN106146303A (en) * | 2016-07-26 | 2016-11-23 | 江门谦信化工发展有限公司 | A kind of acetic acid mixes continuous process system and the method for butyl ester |
| CN107954866A (en) * | 2017-12-13 | 2018-04-24 | 中国石油大学(华东) | The method and its device of differential pressure heat coupled reaction rectifying synthesis of acetic acid isopropyl ester |
| CN110963913A (en) * | 2018-09-05 | 2020-04-07 | 泰兴市洁源环保工程有限公司 | Ethyl acetate production process |
| CN110437064A (en) * | 2019-07-24 | 2019-11-12 | 江门谦信化工发展有限公司 | A kind of differential pressure type energy-saving processing technique of ethyl acetate |
Non-Patent Citations (1)
| Title |
|---|
| 黄英: "《化工过程节能与优化设计》", 28 February 2018, 西北工业大学出版社 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113082757A (en) * | 2021-05-12 | 2021-07-09 | 重庆市中润化学有限公司 | NMP (N-methyl pyrrolidone) rectifying device |
| CN114751822A (en) * | 2022-03-16 | 2022-07-15 | 浙江建业化工股份有限公司 | Device for producing n-propyl acetate through thermal coupling and production method thereof |
| CN114751822B (en) * | 2022-03-16 | 2024-04-09 | 浙江建业化工股份有限公司 | Device for producing n-propyl acetate by thermal coupling and production method thereof |
| CN114917604A (en) * | 2022-05-19 | 2022-08-19 | 北京航天石化技术装备工程有限公司 | System and method for extracting acetophenone from household garbage pyrolysis tar |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112409172B (en) | 2023-04-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112409172B (en) | Method and system for producing ethyl acetate | |
| CN102451572B (en) | Method for separating acetic acid from water by rectification of acetic acid dehydrating tower | |
| CN104557529B (en) | A kind of process for purification for n-propyl acetate lactate synthesis and device | |
| JP6716597B2 (en) | Improved method for producing (meth)acrylic acid | |
| CN1830934A (en) | Method for producing dimethyl ether using methanol as raw material | |
| MXPA06010637A (en) | Utilization of acetic acid reaction heat in other process plants. | |
| WO2004020076A1 (en) | Separator, reactor, and process for producing aromatic carboxylic acid | |
| JP7486861B1 (en) | Process and equipment for the production of vinyl acetate by the ethylene method | |
| CN105693467B (en) | A kind of pentaerythrite energy-saving production method | |
| CN101244970B (en) | Apparatus and technique for producing ethylene with ethyl alcohol | |
| CN108440241A (en) | A kind of purification system and method for high purity cyclohexanol | |
| CN109748790B (en) | Method for producing dimethyl adipate | |
| CN109748791B (en) | Energy-saving method for producing dimethyl adipate | |
| CN100395226C (en) | Method for mass producing butyl acetate by reactive distillation method and using sulfuric acid as catalyst | |
| CN220194825U (en) | Heat integration system for producing ethyl acetate | |
| TW201925151A (en) | Processes for the production of ethylene oxide and ethylene glycol | |
| WO2006109999A1 (en) | Recovering method of acetic acid from effluent of terephthalic acid production process | |
| CN217139251U (en) | Dealcoholization tower system in butyl acrylate preparation | |
| CN102452925B (en) | Method for separating acetic acid from water | |
| RU2517524C2 (en) | Method and apparatus for processing hydrogen in purification unit of terephthalic acid purification device | |
| CN110066261B (en) | Energy-saving water-saving environment-friendly method for preparing furfural | |
| CN102452926B (en) | Method for separating acetic acid and water | |
| CN111943141A (en) | Hydrochloric acid analysis device with negative pressure dehydration function and analysis process | |
| CN101270034B (en) | Technique for preparing dimethyl ether | |
| CN110668920A (en) | Method for preparing ethanol and co-producing cyclohexanol by using reactive distillation method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |