KR20220071678A - Process for manufacturing acrylic acid - Google Patents

Abstract

This application relates to a method for manufacturing acrylic acid. The present invention is a method for manufacturing acrylic acid comprising: a first step of preparing a first aqueous solution of lactic acid by diluting a raw material of lactic acid or a raw material of lactic acid with water; a second step of heat-exchanging the aqueous solution of the first step to form a vaporized second lactic acid vapor and a non-vaporized third aqueous lactic acid solution; a third step of including the non-vaporized third lactic acid aqueous solution in the first lactic acid aqueous solution of the first step to form a mixed lactic acid aqueous solution; and a fourth step of supplying a dilution solution to the vaporized second lactic acid vapor to form a diluted fourth lactic acid vapor and an undiluted fifth lactic acid aqueous solution. The present invention has a feature that can stably supply a gaseous reactor feed.

Description

The manufacturing process of acrylic acid {PROCESS FOR MANUFACTURING ACRYLIC ACID}

The present application relates to a process for the production of acrylic acid.

In general, acrylic acid is produced through the oxidative dehydrogenation reaction of propylene, and acrylic acid is used as a raw material for super absorbent polymers, paints, adhesives, and the like, and its demand is increasing. In particular, superabsorbent polymers are used in hygiene products such as diapers.

Until now, many of the chemical products have been manufactured using the raw material derived from fossil raw materials, such as coal and petroleum. However, in recent years, from the viewpoint of preventing global warming and protecting the environment, attention has been paid to using recyclable biological resources as a carbon source as a substitute for conventional fossil raw materials. For example, the development of methods using biomass resources such as starch-based biomass such as corn and wheat, carbohydrate-based biomass such as sugar cane, and cellulosic biomass such as rapeseed or rice straw as raw materials has been attempted. have.

In other words, research with excellent characteristics from the point of view of environmental protection while obtaining sustainability by manufacturing chemical products based on eco-friendly raw materials by breaking away from the traditional petrochemical-based manufacturing process is in progress.

As one of the types of reaction for producing other chemical products from lactic acid, there is a gas phase reaction in which a raw material containing lactic acid is evaporated, contacted with a catalyst in a gaseous state, and a product is obtained. For example, a gas-phase dehydration method using a solid catalyst is known as a technology for producing acrylic acid using lactic acid, and research on the dehydration reaction of lactic acid is mainly in progress as a gas-phase reaction.

Lactic acid is a substance that polymerizes while esterification occurs in the liquid phase without a catalyst in the absence of water. As lactic acid is oligomerized and dehydrated, the oligomerization reaction of lactic acid occurs as lactic acid is concentrated without water.

When the lactic acid oligomer is introduced into the reactor for the production of acrylic acid, fouling occurs in the reactor and the reaction yield is lowered. Therefore, a method for reducing the content of the lactic acid oligomer for the production of acrylic acid is being studied.

Among them, in order to lower the content of lactic acid oligomer, it is supplied to the vaporizer in the form of an aqueous lactic acid solution, but water with a low boiling point is vaporized first in the vaporizer and lactic acid is vaporized. is occurring

In addition, it is possible to use a distillation column that separates using the boiling point difference so that the vaporized lactic acid aqueous solution does not contain oligomers. is occurring

Therefore, in order to solve this problem, research is being conducted to lower the content of lactic acid oligomer and increase the yield of acrylic acid produced.

International Publication No. 2005-095320

The present application seeks to provide a process for preparing acrylic acid.

An exemplary embodiment of the present application is a first step of preparing a first aqueous lactic acid solution by diluting the lactic acid raw material or the lactic acid raw material with water; a second step of heat exchanging the aqueous solution of the first step to form a second vaporized lactic acid vapor and a third non-vaporized aqueous lactic acid solution; a third step of forming a mixed lactic acid aqueous solution by including the non-vaporized third aqueous lactic acid solution in the first aqueous lactic acid solution of the first step; and a fourth step of supplying a diluent to the vaporized second lactic acid vapor to form a fourth diluted lactic acid vapor and an undiluted fifth lactic acid aqueous solution;

The diluent is water; and vaporized steam, wherein the diluent includes at least vaporized steam.

In the case of the manufacturing process of acrylic acid according to an exemplary embodiment of the present application, the process of supplying a diluent containing low-pressure steam to the vaporized second lactic acid vapor through a heat exchanger includes the step of diluting the lactic acid raw material (first The capacity of the heat exchanger itself can be reduced by reducing the amount of water input in step) and supplying the reduced amount as low-pressure steam to the second lactic acid steam, thereby reducing the flow rate to be vaporized in the heat exchanger itself. have characteristics.

In particular, the energy cost of the process can be lowered by supplying a diluent containing low-pressure steam, which has a low manufacturing cost. Due to the low steam temperature, the liquid lactic acid aqueous solution (5th lactic acid aqueous solution) condensed together during dilution passes through a gas-liquid separator. As it is circulated back to the heat exchanger, it has the characteristic of stably supplying gaseous reactor feed.

1 is a schematic diagram of an acrylic acid manufacturing process according to an exemplary embodiment of the present application.
Figure 2 is a schematic diagram of an acrylic acid manufacturing process according to another exemplary embodiment of the present application.
3 is a schematic diagram of an acrylic acid manufacturing process according to another exemplary embodiment of the present application.
4 is a schematic diagram of an acrylic acid manufacturing process according to Comparative Example 1 of the present application.

Hereinafter, the present specification will be described in more detail.

In the present specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

In the present specification, 'p to q' means a range of 'p or more and q or less'.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

An exemplary embodiment of the present application is a first step of preparing a first aqueous lactic acid solution by diluting the lactic acid raw material or the lactic acid raw material with water; a second step of heat exchanging the aqueous solution of the first step to form a second vaporized lactic acid vapor and a third non-vaporized aqueous lactic acid solution; a third step of forming a mixed lactic acid aqueous solution by including the non-vaporized third aqueous lactic acid solution in the first aqueous lactic acid solution of the first step; and a fourth step of supplying a diluent to the vaporized second lactic acid vapor to form a fourth diluted lactic acid vapor and an undiluted fifth lactic acid aqueous solution;

The diluent is water; and vaporized steam, wherein the diluent includes at least vaporized steam.

In the case of the manufacturing process of acrylic acid according to an exemplary embodiment of the present application, the process of supplying a diluent containing low-pressure steam to the vaporized second lactic acid vapor through a heat exchanger includes the step of diluting the lactic acid raw material (first The capacity of the heat exchanger itself can be reduced by reducing the amount of water input in step) and supplying the reduced amount as low-pressure steam to the second lactic acid steam, thereby reducing the flow rate to be vaporized in the heat exchanger itself. have characteristics. In particular, the energy cost of the process can be lowered by supplying a diluent containing low-pressure steam, which has a low manufacturing cost. Due to the low steam temperature, the liquid lactic acid aqueous solution (5th lactic acid aqueous solution) condensed together during dilution passes through a gas-liquid separator. As it is circulated back to the heat exchanger, it has the characteristic of stably supplying gaseous reactor feed.

In an exemplary embodiment of the present application, a first step of preparing a first aqueous lactic acid solution is provided by diluting the lactic acid raw material or the lactic acid raw material with water.

In an exemplary embodiment of the present application, the first step may include a step of diluting through a dilution vessel.

Specifically, the first step according to the present application can be confirmed in FIGS. 1 to 3, in which the lactic acid raw material (1) and water (2) are added to the dilution vessel 100 to be diluted, and the first aqueous lactic acid solution (3) It can be seen that the formation of At this time, the first lactic acid aqueous solution 3 may be a single lactic acid raw material 1 to which water 2 is not supplied, or an aqueous solution obtained by diluting the lactic acid raw acid 1 with water 2 .

In an exemplary embodiment of the present application, the lactic acid raw material is water; lactic acid; and lactic acid oligomers.

In the present application, the lactic acid is lactic acid, which is an organic compound having an asymmetric carbon atom bonded to four atomic groups of a carboxy group, a hydroxyl group, a methyl group, and hydrogen, and includes both D-lactic acid and L-lactic acid, and is a single lactic acid monomer. can mean

In the present application, the lactic acid oligomer refers to a material in which lactic acid reacts with each other to form a dimer, a trimer, etc., and the lactic acid oligomer may refer to a dimer to 100mer of lactic acid.

Lactic acid is a substance that polymerizes through an esterification reaction in a liquid phase without a catalyst even in the absence of water. That is, except for a single lactic acid monomer, all substances formed through a polymerization reaction of lactic acid may be defined as lactic acid oligomers.

In an exemplary embodiment of the present application, the first step is a step of diluting with water in the raw lactic acid state, and may refer to a step for minimizing oligomers by increasing the content of water produced during the equilibrium reaction of lactic acid oligomer formation.

In the case of the manufacturing process of acrylic acid according to an exemplary embodiment of the present application, the amount of water input in the dilution step (first step) of the lactic acid raw material is reduced, and the reduced amount is supplied to the second lactic acid steam as low pressure steam. , It is characterized in that the flow rate to be vaporized in the heat exchanger itself is reduced, and the step of diluting the lactic acid raw material with water in the first step can be omitted.

That is, the first aqueous lactic acid solution is a step of diluting the lactic acid raw material alone or the lactic acid raw material that is not diluted with water with a small amount of water. Meaning, as described above, the present invention is characterized in that it is possible to reduce the amount of heat in the heat exchanger in the second step by minimizing the amount of water in the first step.

In an exemplary embodiment of the present application, the first aqueous lactic acid solution is water; and a lactic acid raw material, wherein the lactic acid raw material is lactic acid; and a lactic acid oligomer, and provides a process for producing acrylic acid comprising 50 parts by weight or more and 99 parts by weight or less of the lactic acid raw material based on 100 parts by weight of the first aqueous lactic acid solution.

In another exemplary embodiment, based on 100 parts by weight of the first aqueous lactic acid solution, 50 parts by weight or more and 99 parts by weight or less, preferably 60 parts by weight or more and 99 parts by weight or less, more preferably 80 parts by weight or more and 99 parts by weight or more It may include parts by weight or less.

In the first step, when the lactic acid raw material is diluted, the amount of water is reduced and the amount is supplied as low pressure steam to the vaporized lactic acid aqueous solution (second lactic acid steam), which should be vaporized in the heat exchanger itself. It is a feature of the present application that by reducing the flow rate, the capacity of the heat exchanger itself can be reduced. That is, the content of the lactic acid raw material in the first aqueous lactic acid solution is increased, the amount of water is decreased to decrease the heat amount of the heat exchanger, and then, the low pressure steam is supplied in the vaporized second lactic acid vapor state.

In an exemplary embodiment of the present application, there is provided a second step of heat exchanging the aqueous solution of the first step to form a second vaporized lactic acid vapor and a third non-vaporized lactic acid aqueous solution.

In this case, the second step may include a process of exchanging heat through a heat exchanger.

Specifically, the second step according to the present application can be confirmed in FIGS. 1 to 3, heat exchange with the first aqueous lactic acid solution 3 through the heat exchanger 200, and vaporized second lactic acid vapor 5 ) and it can be confirmed that the third aqueous lactic acid solution 6 that is not vaporized is formed. In particular, in the present invention, the non-vaporized third aqueous lactic acid solution 6 is circulated and included in the aqueous solution of the first step for heat exchange. Same as (4), and then, as can be seen in FIGS. 1 and 2, in the step of heat exchanging the aqueous solution of the first step, which is the mixed lactic acid aqueous solution (4) including the third aqueous lactic acid solution (6) that is not vaporized corresponds to

That is, in the first process in FIGS. 1 and 2 , the first aqueous lactic acid aqueous solution 3 is the same as the mixed lactic acid aqueous solution 4, and the mixed lactic acid aqueous solution 4 is the first aqueous lactic acid solution 1 and It corresponds to the step of heat exchanging the combined aqueous solution (aqueous solution of the first step) of the third aqueous lactic acid solution 6 that has not been vaporized.

In the exemplary embodiment of the present application, the third aqueous lactic acid solution that has not been vaporized is included in the aqueous solution of the first step again through the liquid-phase circulation flow in the heat exchanger, so that acrylic acid can be produced without loss of lactic acid raw material will have characteristics.

In an exemplary embodiment of the present application, the heat exchanger is selected from the group consisting of a falling film evaporator, a thin film evaporator, a thermosyphon and a forced circulation evaporator. It may be 1 or more, and if the first aqueous lactic acid solution can be vaporized, it is not limited thereto.

That is, in the exemplary embodiment of the present application, the second step is a step of vaporizing the aqueous solution of the first step, and the reaction for producing acrylic acid from lactic acid is mainly conducted as a gas phase reaction, and thus the liquid first step It may be a step related to a process of vaporizing the aqueous solution of the step into a gas phase.

In the exemplary embodiment of the present application, as the first aqueous lactic acid solution is vaporized, the vaporized second lactic acid vapor and non-vaporized third lactic acid aqueous solution are formed, and the vaporized second lactic acid vapor is a third non-vaporized lactic acid vapor The content of lactic acid oligomer is maintained lower than that of the lactic acid aqueous solution.

In an exemplary embodiment of the present application, as the water content of the first aqueous lactic acid solution is lowered in the first step, and the amount is included as a diluent containing steam vaporized in the fourth step to be described later, the heat exchanger can reduce calories.

In an exemplary embodiment of the present application, the internal pressure of the heat exchanger is 1.0 bar or more and 5.0 bar or less, and the internal temperature of the heat exchanger is 150°C or more and 350°C or less.

In another exemplary embodiment, the internal pressure of the heat exchanger may be 1.0 bar or more and 5.0 bar or less, preferably 1.1 bar or more and 5.0 bar or less, and more preferably 1.5 bar or more and 4.5 bar or less.

In another exemplary embodiment, the internal temperature of the heat exchanger may be 210 °C or higher, preferably 215 °C or higher, more preferably 220 °C or higher, and 350 °C or lower.

By adjusting the pressure of the heat exchanger to the above range, the temperature of the heat exchanger can be properly maintained within the above range, and the pressure difference with the reactor can be reduced later to suitably form the capacity of the compressor for the subsequent process. have possible characteristics. In addition, as the temperature of the heat exchanger is adjusted within the above range, vaporization of the aqueous solution included in the heat exchanger in the first step may occur, and decomposition of the lactic acid raw material does not occur, thereby increasing the yield of acrylic acid.

In an exemplary embodiment of the present application, the heat amount of the heat exchanger provides a process for producing acrylic acid that is 5.0 Gcal/hr or less.

In another exemplary embodiment, the heat quantity of the heat exchanger may be 5.0 Gcal/hr or less, preferably 4.0 Gcal/hr or less, more preferably 3.8 Gcal/hr or less, and 1.0 Gcal/hr or more.

As described above, the amount of heat in the heat exchanger is within the above range. In particular, when the lactic acid raw material is diluted in the first step or when additional water is added to the heat exchanger, the amount of water is reduced and the amount of vaporized vaporized water is described later. By supplying low-pressure steam to the lactic acid vapor in the state (second lactic acid vapor) to reduce the flow rate to be vaporized in the heat exchanger itself, the capacity of the heat exchanger itself can be reduced.

In an exemplary embodiment of the present application, the second lactic acid vapor is water; and a lactic acid raw material, wherein the lactic acid raw material is lactic acid; and a lactic acid oligomer, and provides a process for producing acrylic acid comprising 50 parts by weight or more and 99 parts by weight or less of the lactic acid raw material based on 100 parts by weight of the second lactic acid vapor.

In another exemplary embodiment, based on 100 parts by weight of the second lactic acid vapor, 50 parts by weight or more and 99 parts by weight or less, preferably 50 parts by weight or more and 98 parts by weight or less, more preferably 53 parts by weight or more and 98 parts by weight or more It may be less than or equal to parts by weight.

In an exemplary embodiment of the present application, the third aqueous lactic acid solution that is not vaporized may be included in the aqueous solution of the first step again through a liquid flow, and the first aqueous lactic acid solution includes the third aqueous lactic acid solution that is not vaporized A mixed aqueous lactic acid solution can be formed.

In the case of the third aqueous lactic acid solution, a lactic acid oligomer is formed through an oligomerization reaction of concentrated lactic acid and is recycled without being vaporized. may be included.

After that, since the process of diluting by adding water to the first aqueous lactic acid solution containing the third aqueous lactic acid solution proceeds, the content of lactic acid oligomers in the lactic acid aqueous solution introduced into the heat exchanger through the equilibrium reaction can be reduced as much as possible.

In an exemplary embodiment of the present application, the mixed lactic acid aqueous solution includes lactic acid, lactic acid oligomers and water, and 1.5 parts by weight or less of the water based on 100 parts by weight of the mixed lactic acid aqueous solution It provides a manufacturing process of acrylic acid .

In another exemplary embodiment, the mixed lactic acid aqueous solution includes lactic acid, lactic acid oligomers, and water, and may be 1.5 parts by weight or less, preferably 1.4 parts by weight or less, of the water based on 100 parts by weight of the mixed lactic acid aqueous solution, and 0.01 parts by weight Partial or more, preferably 0.02 parts by weight or more.

The mixed lactic acid aqueous solution refers to the lactic acid aqueous solution immediately before being put into the heat exchanger. The content of water in the mixed lactic acid aqueous solution satisfies the above range, and the amount of water to be vaporized in the heat exchanger is reduced, so the heat amount of the heat exchanger itself It is a feature of the present invention that the decomposition of the lactic acid oligomer is also possible by supplying the amount of water reduced in the fourth step to be described later as vaporized steam.

In the exemplary embodiment of the present application, a fourth step of supplying a diluent to the vaporized second lactic acid vapor to form a fourth diluted lactic acid vapor and an undiluted fifth lactic acid aqueous solution may include.

That is, even in the state of the second lactic acid vapor vaporized through the second step, the content of lactic acid oligomer is high, which may be a problem. It is characterized in that it includes 4 steps.

Specifically, in the fourth step according to an exemplary embodiment of the present application, as in FIG. 1 , the diluent 7 is supplied to the second lactic acid vapor 5 to form a diluted fourth lactic acid vapor 8 . can check that

In the fourth step according to another exemplary embodiment, the diluent 7 is supplied to the second lactic acid vapor 5 through the gas-liquid separator 300 as shown in FIG. 2, and the diluted fourth lactic acid vapor 8 and An undiluted fifth aqueous lactic acid solution may be formed.

In particular, when the vaporized second lactic acid vapor is diluted using low-pressure saturated steam as a diluent, a portion of the second lactic acid vapor may be condensed, so separating the liquid phase in the gas-liquid separator and recycling it back to the heat exchanger The reactor feed can be supplied stably.

The process for producing acrylic acid according to the present application comprises at least vaporized steam as a diluent in the vaporized second lactic acid vapor to efficiently decompose lactic acid oligomers in a short time to form lactic acid monomers. do.

In an exemplary embodiment of the present application, the fourth step may include a process of diluting through a gas-liquid separator.

In an exemplary embodiment of the present application, the fourth step includes a step of diluting by supplying the diluent to the gas-liquid separator, the internal pressure of the gas-liquid separator is 1.0 bar or more and 5.0 bar or less, and the gas-liquid separator internal temperature is 150 It provides a process for producing acrylic acid that is ℃ or more and 350 ℃ or less.

In another exemplary embodiment, the internal pressure of the gas-liquid separator may be 1.0 bar or more and 5.0 bar or less, preferably 1.3 bar or more and 5.0 bar or less, and more preferably 1.5 bar or more and 4.5 bar or less.

As described above, as the internal pressure of the gas-liquid separator has the above range, the liquid phase of the lactic acid raw material input for dilution can be maintained.

In another exemplary embodiment, the internal temperature of the gas-liquid separator may be 150°C or more and 350°C or less, preferably 150°C or more and 330°C or less, and more preferably 170°C or more and 300°C or less.

In the exemplary embodiment of the present application, in order for the second lactic acid vapor stream generated in the heat exchanger to be supplied to the gas-liquid separator without going through a compressor, the internal pressure of the gas-liquid separator should be maintained lower than that of the heat exchanger, specifically, the The gas-liquid separator internal pressure may have a pressure difference of 0.01 bar or more and 1.5 bar or less, preferably 0.02 bar or more and 1 bar or less, and more preferably 0.05 bar or more and 0.5 bar or less.

In an exemplary embodiment of the present application, the pressure of the diluent injected into the gas-liquid separator is higher than the internal pressure of the gas-liquid separator by 1.0 bar or more and 2.0 bar or less.

In an exemplary embodiment of the present application, the temperature of the diluent may be 250° C. or less, preferably 230° C. or less, more preferably 200° C. or less, and 110° C. or higher.

That is, the minimum pressure of the low-pressure steam used as the diluent may be equal to or slightly higher than the gas-liquid separator pressure. That is, it is not necessary to use high-pressure saturated steam with high temperature and pressure because the temperature of the heat exchanger is high, and it is possible to use low-temperature and low-pressure steam with a slightly higher pressure than the heat exchanger as another feature of the present invention. have.

In an exemplary embodiment of the present application, the residence time of the second lactic acid vapor in the gas-liquid separator is 3 minutes or more and 15 minutes or less to provide a process for producing acrylic acid.

In another exemplary embodiment, the residence time of the second lactic acid vapor in the gas-liquid separator may be 3 minutes or more and 15 minutes or less, preferably 3 minutes or more and 13 minutes or less, and more preferably 3 minutes or more and 10 minutes or less. .

The lower the residence time of the second lactic acid vapor in the gas-liquid separator is, the more advantageous, and as the minimum above range is satisfied, it is economically advantageous by lowering the reaction time of the entire process.

In an exemplary embodiment of the present application, a fourth lactic acid vapor may be formed through the dilution process, and the fourth lactic acid vapor may include water; and lactic acid raw materials,

The lactic acid raw material is lactic acid; and a lactic acid oligomer, and provides a process for producing acrylic acid comprising 10 parts by weight or more and 80 parts by weight or less of the lactic acid raw material based on 100 parts by weight of the fourth lactic acid vapor.

In another exemplary embodiment, based on 100 parts by weight of the fourth lactic acid vapor, 10 parts by weight or more and 80 parts by weight or less, preferably 30 parts by weight or more and 80 parts by weight or less, more preferably 35 parts by weight or more and 65 parts by weight or more It may be less than or equal to parts by weight.

In an exemplary embodiment of the present application, there is provided a process for producing acrylic acid that further comprises the step of supplying the diluent to the mixed lactic acid aqueous solution of the third step to form a diluted mixed lactic acid aqueous solution.

That is, the diluent included in the fourth step is, as can be seen in FIG. 3 , the diluent 7 itself is divided and the diluent 7-1 supplied to the gas-liquid separator 300 and the diluent supplied to the mixed lactic acid aqueous solution 4 It can be divided into (7-2).

In addition, in an exemplary embodiment of the present application, there is provided a process for producing acrylic acid that further comprises the step of including the undiluted fifth aqueous lactic acid solution in the aqueous solution of the first step.

That is, the fifth aqueous lactic acid solution condensed in the gas-liquid separator of the fourth step is included in the first step again, and as can be seen in FIGS. 2 and 3 , the fifth aqueous lactic acid solution 9 is supplied to the dilute vessel 100. It can be seen that the circulation flow of the liquid phase is shown.

The manufacturing process of acrylic acid according to the present invention can have excellent characteristics in terms of environmental protection while obtaining sustainability by producing acrylic acid based on lactic acid, which is an eco-friendly raw material, by breaking away from the traditional petrochemical-based manufacturing process. The fourth lactic acid vapor is an aqueous lactic acid solution in a state of being input to the final reactor, and through the dilution process with the diluent as described above, the acrylic acid production process according to the present application includes a step of lowering the content of lactic acid oligomer once more, It is possible to reduce the occurrence of fouling in the reactor for the final acrylic acid production process, and has a feature that can increase the reaction yield.

In an exemplary embodiment of the present application, the production of acrylic acid comprising the step of supplying a diluent to the vaporized second lactic acid vapor to form a fourth lactic acid vapor, and including the diluent in the aqueous solution of the first step process is provided.

That is, as described above, the first aqueous lactic acid solution in the first step may include the diluent.

The production process of the present invention is particularly useful for the synthesis of acrylic acid, and specifically, acrylic acid can be produced by contacting the vapor composition containing lactic acid obtained in the present invention with a dehydration catalyst. The generated reaction gas is collected and liquefied by cooling or contact with a collection liquid, and high-purity acrylic acid can be obtained through a purification process such as extractive distillation and crystallization. The produced acrylic acid is widely used as a raw material for water-absorbing resins, paints, adhesives, and the like.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

Examples and comparative examples of the present invention can be simulated by Aspentech's Aspen Plus.

< production example >

< comparative example 1>

As can be seen in FIG. 4 , the purified lactic acid raw material (1) was diluted in water (2) and then put into the heat exchanger (200). In the heat exchanger 200, 3% of the vaporized and non-vaporized liquid phase (third aqueous lactic acid solution) was recirculated to the heat exchanger (6), and the vaporized gaseous lactic acid stream (second lactic acid vapor, 5) was used as reactor feed. . The water used for dilution is 6 ton/hr, and the heat exchanger's calorific value is 5.7 Gcal/hr. The flow rate and temperature according to the flow in FIG. 4 were shown in Table 1 below.

One 2 3 4 5 6 Temperature (℃) 40 40 40 192 218 218 flux
(kg/hr) Total 5.0 6.0 11.0 341.0 11.0 330.0 water 0.7 6.0 6.6 8.6 6.7 2.0 lactic acid 3.1 0.0 4.2 39.1 3.8 34.9 lactic acid oligomer 1.2 0.0 0.2 293.4 0.5 293.2

< Example 1>

As can be seen in Figure 1, the purified lactic acid raw material (1) was put into a heat exchanger. In the heat exchanger 200, 2% is vaporized, the non-vaporized liquid phase is recirculated (third aqueous lactic acid solution, 6), and the vaporized gaseous lactic acid stream (second lactic acid vapor, 5) is a diluent containing vaporized steam ( The fourth lactic acid vapor (8) obtained by mixing 7) was used as a reactor feed.

The supplied saturated steam flow rate was 6ton/hr, the temperature was 200℃, the pressure was 11.5bar, and the heat quantity of the heat exchanger was 2.1Gcal/hr. The flow rate and temperature according to the flow in FIG. 1 were shown in Table 2 below.

One 2 3 4 5 6 7 8 Temperature (℃) 40 40 40 292 312 311 200 248 flux
(kg/hr) Total 5.0 0.0 5.0 335.0 5.0 330.1 6.0 11.0 water 0.7 0.0 0.7 0.8 0.7 0.1 6.0 6.7 lactic acid 3.1 0.0 3.1 5.5 3.3 2.5 0.0 3.3 lactic acid oligomer 1.2 0.0 1.2 328.7 1.0 327.5 0.0 1.0

< Example 2>

In Example 1, it was carried out in the same manner as in Example 1, except that the flow rate and temperature of Table 3 were changed, and the specific contents were the same as in Table 3 below.

One 2 3 4 5 6 7 8 Temperature (℃) 40 40 40 215 236 236 200 226 flux
(kg/hr) Total 5.0 3.0 8.0 338.0 8.0 330.0 3.0 11.0 water 0.7 3.0 3.6 4.7 3.7 1.1 3.0 6.7 lactic acid 3.1 0.0 4.0 25.7 3.8 21.7 0.0 3.8 lactic acid oligomer 1.2 0.0 0.3 307.5 0.6 307.2 0.0 0.6

< Example 3>

As can be seen in Figure 2, the purified lactic acid raw material (1) was put into the heat exchanger. In the heat exchanger 200, 2% is vaporized, the non-vaporized liquid phase is recirculated (third aqueous lactic acid solution, 6), and the vaporized gaseous lactic acid stream (second lactic acid vapor, 5) is a diluent containing vaporized steam ( 7) and the gas-liquid separator 300 are mixed. The liquid phase condensed in the gas-liquid separator (5 lactic acid aqueous solution, 9) was recycled (9) and the diluted gaseous stream (fourth lactic acid vapor, 8) was used as reactor feed.

The supplied saturated steam flow rate was 6ton/hr, the temperature was 111℃, the pressure was 1.5bar, and the heat quantity of the heat exchanger was 2.1Gcal/hr. The flow rate and temperature according to the flow in FIG. 2 were shown in Table 4 below.

One 2 3 4 5 6 7 8 9 Temperature (℃) 40 40 40 298 318 319 111 207 207 flux
(kg/hr) Total 5.0 0.0 5.0 335.2 5.2 330.0 6.0 11.0 0.2 water 0.7 0.0 0.7 0.8 0.7 6.0 6.0 6.7 0.0 lactic acid 3.1 0.0 3.1 5.2 3.4 2.1 0.0 3.3 0.1 lactic acid oligomer 1.2 0.0 1.2 329.2 1.1 327.9 0.0 1.0 0.1

< Example 4>

As can be seen in Figure 3, the purified lactic acid raw material (1) was put into the heat exchanger. In the heat exchanger 200, 2% was vaporized, and the non-vaporized liquid was recycled (the third aqueous lactic acid solution, 6). Afterwards, the diluent 7 containing vaporized steam was mixed in the gas-liquid separator 300 and the mixed lactic acid aqueous solution 4, respectively, and specifically, the vaporized gaseous lactic acid stream (the second lactic acid vapor, 5) is the vaporized steam The containing diluent (7-1) is mixed with the gas-liquid separator (300). The liquid phase condensed in the gas-liquid separator (5 lactic acid aqueous solution, 9) was recycled (9) and the diluted gaseous stream (fourth lactic acid vapor, 8) was used as reactor feed.

The supplied saturated steam flow rate was 6ton/hr, the temperature was 111℃, the pressure was 1.5bar, and the heat quantity of the heat exchanger was 2.1Gcal/hr. The flow rate and temperature according to the flow in FIG. 3 were shown in Table 5 below.

One 2 3 4 5 6 7-1 7-2 8 9 Temperature (℃) 40 40 40 254 270 270 111 111 206 206 flux
(kg/hr) Total 5.0 0.0 5.0 336.2 6.3 330.0 1.0 5.0 11.0 0.3 water 0.7 0.0 0.7 2.1 1.0 0.3 1.0 5.0 6.7 0.0 lactic acid 3.1 0.0 3.1 10.6 3.7 7.4 0.0 0.0 3.6 0.1 lactic acid oligomer 1.2 0.0 1.2 323.6 1.6 322.3 0.0 0.0 0.8 0.1

The input amount of water and steam of the diluent in the fourth step according to Examples 1 to 4, the amount of heat in the heat exchanger, the capacity reduction ratio of the heat exchanger compared to Comparative Example 1, and the temperature of the heat exchanger and the water in the first step of Comparative Example 1 and the amount of steam input, the heat amount of the heat exchanger, and the temperature of the heat exchanger were shown in Table 6 below.

Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Water input (T/h) 6 0 3 0 0 Steam input (T/h) 0 6 3 6 6 Heat exchanger calorific value (Gcla/hr) 5.7 2.1 3.8 2.1 2.1 Ratio of heat exchanger capacity reduction compared to Comparative Example 1 - 65% 33% 65% 65% Heat exchanger temperature (℃) 218 312 237 318 270

As can be seen in Examples 1 to 4 of Table 6, in the case of the manufacturing process of acrylic acid according to the present application, the process of supplying a diluent containing low pressure steam to the vaporized second lactic acid vapor through a heat exchanger. As a result, the amount of water input in the dilution step (first step) of the lactic acid raw material is reduced, and the reduced amount is supplied to the second lactic acid steam as low pressure steam, thereby reducing the flow rate to be vaporized in the heat exchanger itself. It was confirmed that the capacity of the heat exchanger itself can be reduced by doing In the case of Example 4, it was confirmed that the heat exchanger capacity was reduced to 65%.

In particular, in the case of Examples 3 and 4, the energy cost of the process can be lowered by supplying a diluent containing low-pressure steam, which has a low manufacturing cost, and a liquid lactic acid aqueous solution condensed together during dilution due to the low steam temperature (the first 5 lactic acid aqueous solution) is circulated back to the heat exchanger through the gas-liquid separator, and thus has the characteristic of stably supplying the reactor feed in the gas phase.

In the case of Comparative Example 1 of Table 6, the step of supplying the diluent in the fourth step according to the present application is not included, and when the amount of water is increased in the first step, the heat amount of the heat exchanger itself is the same as in Example 1 It was confirmed that the capacity of the heat exchanger has to be increased to supply heat energy in the process because it is higher than 4, and thus economically poor results are obtained.

100: dilution vessel
200: heat exchanger
300: gas-liquid separator
1: lactic acid raw material
2: water
3: First aqueous lactic acid solution
4: Mixed lactic acid aqueous solution
5: Second lactic acid vapor
6: Third aqueous lactic acid solution (liquid flow)
7, 7-1, 7-2: diluent
8: quaternary lactic acid vapor
9: Fifth lactic acid aqueous solution

Claims (10)

A first step of preparing a first aqueous lactic acid solution by diluting the lactic acid raw material or the lactic acid raw material with water;
a second step of heat exchanging the aqueous solution of the first step to form a second vaporized lactic acid vapor and a third non-vaporized lactic acid aqueous solution;
a third step of forming a mixed lactic acid aqueous solution by including the non-vaporized third aqueous lactic acid solution in the first aqueous lactic acid solution of the first step; and
a fourth step of supplying a diluent to the vaporized second lactic acid vapor to form a fourth diluted lactic acid vapor and an undiluted fifth lactic acid aqueous solution;
As a manufacturing process of acrylic acid comprising a,
The diluent is water; and vaporized steam, wherein the diluent contains at least vaporized steam. The method according to claim 1, wherein the fourth step comprises a step of diluting by supplying the diluent to a gas-liquid separator,
The gas-liquid separator internal pressure is 1.0 bar or more and 5.0 bar or less, and the gas-liquid separator internal temperature is 150°C or more and 350°C or less. The process for producing acrylic acid according to claim 2, wherein the residence time of the second lactic acid vapor in the gas-liquid separator is 3 minutes or more and 15 minutes or less. The process for producing acrylic acid according to claim 1, further comprising the step of supplying the diluent to the mixed lactic acid aqueous solution of the third step to form a diluted mixed lactic acid aqueous solution. The method according to claim 1, wherein the mixed lactic acid aqueous solution comprises lactic acid, lactic acid oligomer and water,
The manufacturing process of acrylic acid comprising 1.5 parts by weight or less of the water based on 100 parts by weight of the mixed lactic acid aqueous solution. The method according to claim 1, wherein the second step comprises a process of exchanging heat through a heat exchanger,
The internal pressure of the heat exchanger is 1.0 bar or more and 5.0 bar or less, and the internal temperature of the heat exchanger is 150° C. or more and 350° C. or less. The method according to claim 1, wherein the fourth lactic acid vapor is water; and lactic acid raw materials,
The lactic acid raw material is lactic acid; and lactic acid oligomers,
The process for producing acrylic acid comprising 10 parts by weight or more and 80 parts by weight or less of the lactic acid raw material based on 100 parts by weight of the fourth lactic acid vapor. The process according to claim 2, wherein the pressure of the diluent is higher than the internal pressure of the gas-liquid separator by 1.0 bar or more and 2.0 bar or less. The process for producing acrylic acid according to claim 1, further comprising the step of including the undiluted fifth aqueous lactic acid solution in the aqueous solution of the first step. The method according to claim 6, wherein the heat exchanger is a falling film evaporator (falling film evaporator), thin film evaporator (wiped film evaporator), thermosyphon (thermosyphon) and forced circulation evaporator (forced circulation evaporator) at least one selected from the group consisting of The manufacturing process of acrylic acid.

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