Method for vaporizing lactic acid, apparatus for vaporizing lactic acid, and method for preparing acrylic acid

Abstract

To provide an apparatus for vaporizing lactic acid.SOLUTION: According to a method and an apparatus for vaporizing lactic acid of the present disclosure, the content of lactic acid oligomers can be reduced within a short period of time, and the content of lactic acid single-molecules can be increased.SELECTED DRAWING: None

Description

[Technical field]

[0001] [Cross-reference to related applications] This application claims the benefit of priority to Korean Patent Application No. 10-2020-0134656, filed October 16, 2020, Korean Patent Application No. 10-2020-0134655, filed October 16, 2020, Korean Patent Application No. 10-2020-0148082, filed November 6, 2020, and Korean Patent Application No. 10-2020-0183552, filed December 24, 2020, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present specification relates to a method for vaporizing lactic acid, a lactic acid vaporizer, and a method for producing acrylic acid from lactic acid. [Background technology]

[0003] Lactic acid, also written as lactic acid, is an organic acid with a relatively simple structure that contains both hydroxyl groups and carboxyl groups within the molecule.

[0004] Lactic acid has traditionally been produced naturally during the fermentation process of lactose and glucose, and has been used to improve the flavor of fermented foods. As it is non-toxic to the human body, it has been used in a variety of applications in the food industry, such as as a flavoring agent, preservative, and pH regulator, in the beauty industry, such as as a moisturizer and skin whitening agent, and in the medical industry, such as in intravenous injections, dialysis fluids, and calcium supplements.

[0005] Recently, interest has been growing in lactic acid polymers, or polylactides, as biodegradable, environmentally friendly alternative polymers to non-biodegradable plastics such as petroleum-derived polyolefins, polystyrene, and polyesters. They are also attracting a great deal of attention as precursors to acrylic acid, which is of great industrial importance.

[0006] Lactic acid can be mainly produced by microbial fermentation or chemical synthesis, but recently, research has been conducted on methods of producing lactic acid using biomass resources as raw materials, such as starch-based biomass such as corn, sugar-based biomass such as sugar cane, or cellulosic biomass obtained from woody or herbaceous plants.

[0007] Lactic acid obtained in this way is usually stored at a high concentration during storage and distribution after production, but due to the structural characteristics of the lactic acid molecule, which contains both hydroxyl and carboxyl groups within the molecule, it often forms a dimer structure or an oligomer in the form of dehydration condensation after water molecules are removed.

[0008] A large amount of lactic acid is lost due to such dimerization or oligomerization, and oligomerized lactic acid increases the amount of by-products generated in chemical reactions using lactic acid and forms coking during the reaction, significantly reducing the efficiency of the reaction.

[0009] Therefore, when the concentrated and stored lactic acid is used as it is or is input to other chemical reactions, the content of lactic acid oligomers needs to be reduced. It is known that the chemical equilibrium between lactic acid and lactic acid oligomers is related only to the concentration and temperature of lactic acid, and the equilibrium transfer rate is very slow, so there is growing interest in a pretreatment method for using concentrated lactic acid, i.e., a method for reducing the content of lactic acid oligomers and increasing the content of lactic acid monomolecules in the feed. Summary of the Invention [Problem to be solved by the invention]

[0010] The present specification provides a method for vaporizing lactic acid and a device for vaporizing lactic acid, which can reduce the content of lactic acid oligomers in a short time and obtain vaporized lactic acid monomolecules.

[0011] The present specification also provides a method for producing acrylic acid from vaporized lactic acid. [Means for solving the problem]

[0012] The present disclosure provides a method for vaporizing lactic acid, comprising the steps of: heating and pressurizing a lactic acid aqueous solution having a 1-1 concentration; spraying a 1-1 stream of liquid phase containing the heated and pressurized lactic acid aqueous solution having a 1-1 concentration into a vaporization reactor; vaporizing the lactic acid contained in the 1-1 stream by spraying; and obtaining a 1-3 stream of gas phase containing lactic acid molecules.

[0013] According to one embodiment of the invention, in the heating and pressurizing step, the lactic acid aqueous solution of the 1-1 concentration may be heated and pressurized under the following conditions: a temperature of about 150°C to about 250°C, preferably about 150°C or more, or about 160°C or more, and about 250°C or less, or about 200°C or less; and a pressure of about 1 bar to about 40 bar, preferably more than about 1 bar, or about 5 bar or more, and about 40 bar or less, or about 30 bar or less, or about 15 bar or less.

[0014] According to one embodiment of the invention, the 1-1 concentration may be about 20 to about 99 wt%, about 20 wt% or more, about 30 wt% or more, about 40 wt% or more, about 50 wt% or more, about 60 wt% or more, about 70 wt% or more, or about 75 wt% or more, and may be about 99 wt% or less, about 95 wt% or less, about 90 wt% or less, or about 85 wt% or less. That is, the aqueous lactic acid solution may be highly concentrated.

[0015] According to another embodiment of the invention, the temperature of the 1-1 stream, i.e., the temperature of the 1-1 stream to be sprayed, may be about 10 to about 300°C, preferably about 10°C or more, or about 50°C or more, or about 150°C or more, and may be about 300°C or less, or about 250°C or less, or about 200°C or less.

[0016] According to another embodiment of the invention, the 1-1 stream is preferably sprayed at a flow rate of about 0.1 g / min to 1.0 g / min, preferably about 0.1 g / min or more, or about 0.15 g / min or more, and about 1.0 g / min or less, or about 0.5 g / min or less, or about 0.3 g / min or less, and at this time, the temperature inside the reactor may be about 300 to about 400° C.

[0017] That is, the 1-1 stream can be heated and pressurized at a temperature of 150°C to 250°C and a pressure of 1 to 40°C, transferred, and then sprayed in the form of an aerosol into the reactor at normal pressure and at a temperature of about 10°C to about 300°C.

[0018] According to one embodiment of the invention, when spraying the 1-1 stream, the 1-2 stream in a gas phase containing water vapor can be mixed and sprayed.

[0019] The temperature of the 1-2 stream may be about 200 to about 600°C, preferably about 250°C or more, or about 300°C or more, or about 350°C or more, or about 400°C or more, and may be about 600°C or less, or about 550°C or less, or about 530°C or less.

[0020] At this time, the temperature difference between the 1-2 stream and the 1-1 stream is preferably about 200° C. or more, or about 250° C. or more, and about 500° C. or less, or about 450° C. or less.

[0021] It is preferable that the 1-2 stream is sprayed at a flow rate of 0.1 g / min to 3.0 g / min, preferably at a flow rate of about 0.1 g / min or more, or about 0.2 g / min or more, or about 0.3 g / min or more, and about 3.0 g / min or less, or about 2.0 g / min or less, or about 1.0 g / min or less.

[0022] At this time, in the mixing and spraying step, the flow rate of the 1-1 stream: the flow rate of the 1-2 stream is preferably about 1:1.5 to about 1:5.

[0023] Meanwhile, the present invention provides a method for producing acrylic acid, comprising: obtaining lactic acid molecules by vaporizing lactic acid using any one of the above-mentioned methods; producing acrylic acid by dehydrating the lactic acid molecules; and obtaining the acrylic acid.

[0024] The present invention provides a lactic acid vaporization apparatus, comprising: a pretreatment section for heating and pressurizing a lactic acid aqueous solution having a 1-1 concentration; a feed supply section for receiving the lactic acid aqueous solution from the pretreatment section and supplying a 1-1 stream containing the lactic acid aqueous solution; a spray section for spraying the 1-1 stream transferred from the feed supply section into a vaporization reactor; a vaporization reactor in which the sprayed lactic acid aqueous solution is vaporized; and a collection section for collecting a 1-3 stream containing vaporized lactic acid molecules.

[0025] According to one embodiment of the invention, the pretreatment unit may further include a temperature control unit and a pressure control unit that heat and pressurize the lactic acid aqueous solution having the 1-1 concentration at a temperature of about 150°C to about 250°C, preferably at a temperature of about 150°C or more, or about 160°C or more, and about 250°C or less, or about 200°C or less; and at a pressure of about 1 bar to about 40 bar, preferably more than about 1 bar, or about 5 bar or more, and about 40 bar or less, or about 30 bar or less, or about 15 bar or less.

[0026] According to one embodiment of the invention, the 1-1 concentration may be about 20 to about 99 wt%, about 20 wt% or more, about 30 wt% or more, about 40 wt% or more, about 50 wt% or more, about 60 wt% or more, about 70 wt% or more, about 75 wt% or more, and may be about 99 wt% or less, about 95 wt% or less, about 90 wt% or less, or about 85 wt% or less. That is, the lactic acid aqueous solution may be highly concentrated.

[0027] According to another embodiment of the invention, the temperature of the 1-1 stream in the feed supply unit may be about 150 to about 300°C, preferably about 150°C or more, or about 160°C or more, and may be about 300°C or less, or about 250°C or less, or about 200°C or less, and the feed supply unit may further include a feed temperature adjustment unit for adjusting the temperature of the 1-1 stream.

[0028] According to another embodiment of the invention, the spraying unit may include a 1-1 stream nozzle adjusted to spray the 1-1 stream at a flow rate of about 0.1 g / min to 1.0 g / min, preferably at a flow rate of about 0.1 g / min or more, or about 0.15 g / min or more, about 1.0 g / min or less, or about 0.5 g / min or less, or about 0.3 g / min or less.

[0029] According to one embodiment of the invention, the lactic acid vaporization apparatus may further include a water vapor supply unit that supplies water vapor, and the spray unit may further include a 1-2 stream nozzle that receives water vapor from the water vapor generator and sprays a 1-2 stream of gas phase containing water vapor into the vaporization reactor.

[0030] The temperature of the 1-2 stream may be about 200 to about 600°C, preferably about 250°C or more, or about 300°C or more, or about 350°C or more, or about 400°C or more, and may be about 600°C or less, or about 550°C or less, or about 530°C or less.

[0031] For this purpose, the steam supplying unit may further include a steam temperature adjusting unit for adjusting the temperature of the first and second streams.

[0032] At this time, the temperature difference between the 1-2 stream and the 1-1 stream is preferably about 200° C. or more, or about 250° C. or more, and about 500° C. or less, or about 450° C. or less.

[0033] In the spray section, the 1-2 stream is preferably adjusted to be sprayed at a flow rate of 0.1 g / min to 3.0 g / min, preferably at a flow rate of about 0.1 g / min or more, or about 0.2 g / min or more, or about 0.3 g / min or more, and about 3.0 g / min or less, or about 2.0 g / min or less, or about 1.0 g / min or less.

[0034] At this time, it is preferable that the flow rate of the 1-1 stream: the flow rate of the 1-2 stream is adjusted to be 1:1.5 to 1:5 in the spray section.

[0035] Meanwhile, the present specification provides a method for vaporizing lactic acid, comprising the steps of: mixing and spraying a 3-1 stream in a liquid phase containing an aqueous lactic acid solution and a 3-2 stream in a gas phase containing water vapor; vaporizing the aqueous lactic acid solution by heat exchange between the 3-1 stream and the 3-2 stream; and obtaining a 3-3 stream in a gas phase containing lactic acid monomers.

[0036] According to one embodiment of the invention, the aqueous lactic acid solution contained in the 3-1 stream may have a lactic acid concentration of about 40 to about 99 wt%, about 45 wt% or more, or about 50 wt% or more, or about 60 wt% or more, or about 70 wt% or more, or about 75 wt% or more, and may be highly concentrated, such as about 99 wt% or less, about 95 wt% or less, or about 90 wt% or less, or about 85 wt% or less.

[0037] The concentration of polymers in the aqueous lactic acid solution contained in the 3-1 stream, i.e., the concentration of lactic acid dimers or lactic acid oligomers of trimers or higher, may be about 2 to about 55 wt%, or about 2 wt% or more, or about 5% or more, or about 7 wt% or more, or about 8 wt% or more, and may be about 55 wt% or less, or about 40 wt% or less, or about 20 wt% or less, i.e., the content of polymers is relatively high.

[0038] According to another embodiment of the invention, the temperature of the 3-1 stream may be about 10 to about 300°C, preferably about 10°C or more, or about 15°C or more, or about 50°C or more, and may be about 300°C or less, or about 250°C or less, or about 200°C or less.

[0039] The temperature of the 3-2 stream may be about 200 to about 600°C, preferably about 250°C or more, or about 300°C or more, or about 350°C or more, or about 400°C or more, and may be about 600°C or less, or about 550°C or less, or about 530°C or less.

[0040] At this time, the temperature difference between the 3-2 stream and the 3-1 stream is preferably about 200° C. or more, or about 250° C. or more, and about 500° C. or less, or about 450° C. or less.

[0041] According to another embodiment of the invention, the 3-1 stream may be sprayed at a flow rate of 0.05 g / min to 1.5 g / min, with the lower limit being preferably about 0.05 g / min or more, or about 0.1 g / min or more, or about 0.15 g / min or more, or about 0.18 g / min or more, and the upper limit being preferably about 1.5 g / min or less, or about 1.0 g / min or less, or about 0.8 g / min or less.

[0042] The 3-2 stream may be sprayed at a flow rate of 0.1 g / min to 4.0 g / min, with the lower limit being preferably about 0.1 g / min or more, or about 0.2 g / min or more, or about 0.3 g / min or more, and the upper limit being preferably about 4.0 g / min or less, or about 3.0 g / min or less, or about 2.0 g / min or less.

[0043] At this time, in the mixing and spraying step, the flow rate of the 3-1 stream: the flow rate of the 3-2 stream is preferably about 1:1.5 to about 1:5.

[0044] Meanwhile, the present invention provides a method for producing acrylic acid, comprising: obtaining lactic acid molecules by vaporizing lactic acid using any one of the above methods; producing acrylic acid by dehydrating the lactic acid molecules; and obtaining acrylic acid.

[0045] Meanwhile, the present specification provides a lactic acid vaporization apparatus including a feed supply unit 100 for supplying a 3-1 stream containing an aqueous lactic acid solution; a steam supply unit 200 for supplying a 3-2 stream containing water vapor; a vaporization reaction unit 300 for receiving the 3-1 stream from the feed supply unit and the 3-2 stream from the steam supply unit and performing a vaporization reaction of the aqueous lactic acid solution; and a collection unit 400 for collecting a 3-3 stream containing vaporized lactic acid molecules.

[0046] The vaporization reaction section 300 may include a spray section 310 at its lower end for spraying the 3-1 stream supplied from the feed supply section and the 3-2 stream supplied from the steam supply section into the vaporization reaction section.

[0047] The feed supply section may include an aqueous lactic acid feed 110 that supplies an aqueous lactic acid solution; and a feed pre-treatment section 120 for adjusting the temperature and pressure of the 3-1 stream.

[0048] At this time, the feed pre-treatment section 120 may adjust the temperature of the 3-1 stream to about 10 to about 300° C. before discharging it.

[0049] And the water vapor supply may include a water supply 210 that supplies water; and a water pretreatment unit 220 for adjusting the temperature and pressure of the 3-2 stream.

[0050] At this time, the water pre-treatment unit 220 may adjust the temperature of the 3-2 stream to about 200 to about 600° C. before discharging it.

[0051] The spraying section may include a mixing spray nozzle that mixes and sprays the third-1 stream and the second stream.

[0052] According to another example, the spraying section may include a 3-1 nozzle that sprays the 3-1 stream and a 3-2 nozzle that sprays the 2-stream.

[0053] In the spray section, the ratio of the 3-1 stream spray flow rate to the 3-2 stream spray flow rate can be adjusted to about 1:1.5 to about 1:5.

[0054] The collection section may be located above the vaporization reactor.

[0055] The harvesting unit may include a gas-liquid separator 410 that separates and discharges the vaporized lactic acid molecules and the liquefied aqueous solution components.

[0056] At this time, the aqueous solution component discharged from the gas-liquid separator can be recovered in the aqueous lactic acid solution feed 110 and reused.

[0057] In the present invention, terms such as 1-1, 1-2, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.

[0058] Furthermore, the terms used in this specification are merely used to describe exemplary embodiments and are not intended to limit the present invention.

[0059] A singular expression includes a plural expression unless the context clearly indicates a different meaning.

[0060] In this specification, the terms "including," "comprising," or "having" are intended to describe embodied features, numbers, steps, components, or combinations thereof, and do not exclude the possibility of one or more other features, numbers, steps, components, combinations or additions thereof.

[0061] Also, in this specification, when a layer or element is referred to as being formed "on" or "on" another layer or element, it means that the layer or element is formed directly on the layer or element, or that other layers or elements may be additionally formed between layers, on the object, or on the substrate.

[0062] Since the present invention can be modified in various ways and can have various forms, specific embodiments are described in detail below. However, this does not limit the present invention to the specific disclosed form, and it should be understood that the present invention includes all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention.

[0063] In this specification, lactic acid is a compound represented by the following chemical formula, and unless otherwise specified in this specification, it is used as a concept that includes all lactic acid isomers, naturally occurring lactic acid dimers, and lactic acid oligomers. [ka]

[0064] The present invention will be described in detail below.

[0065] According to one aspect of the present invention, there is provided a method for vaporizing lactic acid, comprising the steps of: heating and pressurizing a lactic acid aqueous solution of a 1-1 concentration; spraying a 1-1 stream of liquid phase containing the heated and pressurized lactic acid aqueous solution of a 1-1 concentration; vaporizing the lactic acid contained in the 1-1 stream by spraying; and obtaining a 1-3 stream of gas phase containing lactic acid molecules.

[0066] The lactic acid vaporization method can be realized by the following device.

[0067] According to another aspect of the present invention, there is provided a lactic acid vaporization apparatus including: a pretreatment section which heats and pressurizes a lactic acid aqueous solution having a 1-1 concentration; a feed supply section which receives the lactic acid aqueous solution from the pretreatment section and supplies a 1-1 stream containing the lactic acid aqueous solution; a spray section which sprays the 1-1 stream transferred from the feed supply section into a vaporization reactor; a vaporization reactor in which the sprayed lactic acid aqueous solution is vaporized; and a collection section which collects a 1-3 stream containing vaporized lactic acid molecules.

[0068] The inventors of the present invention discovered that when a highly concentrated aqueous lactic acid solution is heated and pressurized to create a high-temperature, high-pressure state, and then sprayed into a vaporization reactor under normal pressure conditions to instantly vaporize it, the oligomer concentration of lactic acid can be efficiently reduced in a very short period of time, and thus completed the present invention.

[0069] Lactic acid is often used in the production of acrylic acid, but when lactic acid is dehydrated to produce acrylic acid, the process is carried out by a gas phase reaction, so it is necessary to vaporize the lactic acid into lactic acid molecules.

[0070] However, as mentioned above, lactic acid is usually stored at a high concentration during storage and distribution after production, and due to the structural characteristics of the lactic acid molecule, which contains both hydroxyl and carboxyl groups within the molecule, it often forms a dimer structure or an oligomer in the form of dehydration condensation after water molecules are removed.

[0071] Such lactic acid oligomer molecules can be carbonized in the vaporization or reaction stage to form coke, reducing the active area of ​​the reaction catalyst, and can also be included as a by-product in the final product. Above all, the presence of lactic acid oligomers significantly reduces the content of monomolecular lactic acid that can participate in the reaction. Therefore, it is necessary to convert the lactic acid oligomers into monomolecular forms in the concentrated lactic acid aqueous solution to reduce the oligomer content and increase the content of monomolecular lactic acid.

[0072] However, when water is simply added to a concentrated aqueous lactic acid solution containing a high content of lactic acid oligomers to dilute the concentration, the equilibrium shift rate is very slow, so it takes a very long time to reduce the content of lactic acid oligomers.

[0073] In general, in order to shorten this time, a high-concentration lactic acid aqueous solution is heated to vaporize it, but since the vaporization efficiency of lactic acid is lower than that of water, water vaporizes first, and the ratio of vaporized lactic acid falls below about 20 wt%. In this case, water vaporizes first, and the concentration of the remaining lactic acid aqueous solution becomes higher, which causes a problem that the concentration of oligomers in the remaining lactic acid aqueous solution also increases.

[0074] Therefore, in a method for vaporizing lactic acid according to one embodiment of the present invention, a lactic acid aqueous solution having a 1-1 concentration is first heated and pressurized to a high temperature and high pressure state, which is then sprayed into a vaporization reactor, and the lactic acid contained in the 1-1 stream is instantly vaporized by the spraying, thereby obtaining a gas-phase 1-3 stream containing vaporized lactic acid molecules.

[0075] That is, according to one embodiment of the present invention, a high-concentration aqueous lactic acid solution is not directly heated and vaporized, but i) The high concentration lactic acid aqueous solution is heated and pressurized again under high temperature and pressure conditions to reach the conditions for spraying, while preventing the phenomenon in which water in the lactic acid aqueous solution evaporates first, ii) supplying a high-temperature, high-pressure aqueous lactic acid solution and spraying it into the vaporization reactor in the form of an aerosol or droplets; iii) The high concentration lactic acid sprayed in the form of an aerosol into the vaporization reactor is vaporized instantly, thereby making it possible to obtain vaporized monomolecular lactic acid. Meanwhile, the above-mentioned lactic acid vaporization method can be realized by the device described below.

[0076] Such an apparatus may include a pretreatment section that heats and pressurizes a lactic acid aqueous solution having a 1-1 concentration; a feed supply section that receives the lactic acid aqueous solution from the pretreatment section and supplies a 1-1 stream containing the lactic acid aqueous solution; a spray section that sprays the 1-1 stream transferred from the feed supply section into a vaporization reactor; a vaporization reactor in which the sprayed lactic acid aqueous solution is vaporized; and a collection section that collects a 1-3 stream containing vaporized lactic acid molecules.

[0077] The concentration of lactic acid in streams 1-3 may be about 30 wt% or less, or about 25 wt% or less, or about 20 wt% or less, although the lower limit may not be significant depending on process conditions, and may be about 0.1 wt% or more, or about 5 wt% or more.

[0078] More specifically, the first to third streams containing lactic acid monomers may contain, for example, the above-mentioned lactic acid oligomers at less than about 1 wt%, preferably less than about 0.5 wt%, or less than about 0.1 wt%, and more preferably are substantially free of lactic acid oligomers.

[0079] Being substantially free of lactic acid oligomers means that the content of lactic acid oligomers is 0 wt % within the limits detectable in the relevant process.

[0080] According to one embodiment of the invention, the 1-1 concentration may be about 20 to about 99 wt%, about 20 wt% or more, about 30 wt% or more, about 40 wt% or more, about 50 wt% or more, about 60 wt% or more, about 70 wt% or more, about 75 wt% or more, and may be about 99 wt% or less, about 95 wt% or less, about 90 wt% or less, or about 85 wt% or less. That is, the lactic acid aqueous solution may be highly concentrated.

[0081] This generally corresponds to the typical concentration of commercial lactic acid feedstock, including the production, storage, distribution, and sale of lactic acid.

[0082] Here, the 1-1 stream, i.e., the aqueous lactic acid solution contained in the lactic acid feed in the process, means a state in which lactic acid is dissolved in water, and naturally contains all of lactic acid monomers, lactic acid dimers, and lactic acid oligomers depending on the temperature and concentration conditions as described above.

[0083] The lactic acid concentration described here also means the concentration of lactic acid compounds including not only monomolecular lactic acid but also monomolecular lactic acid, dimer of lactic acid, and oligomer of lactic acid.

[0084] More specifically, for example, when calculated by computer modeling, the oligomer content by concentration of the total lactic acid-based compounds is as shown in Table 1 below.

[0085] However, there may be some calculation errors depending on the actual calculation model, and the actual measured values ​​may also have some measurement errors depending on the measurement conditions and measurement method (titration method or HPLC). [Table 1]

[0086] According to one embodiment of the invention, in the heating and pressurizing step, the lactic acid aqueous solution of the 1-1 concentration may be heated and pressurized under the following conditions: a temperature of about 150°C to about 250°C, preferably about 150°C or more, or about 160°C or more, and about 250°C or less, or about 200°C or less; and a pressure of about 1 bar to about 40 bar, preferably more than about 1 bar, or about 5 bar or more, and about 40 bar or less, or about 30 bar or less, or about 15 bar or less.

[0087] If the heating and pressurizing step is performed at an excessively low temperature and pressure outside the temperature and pressure range, the temperature of the mixture may be low and the lactic acid may not be sufficiently vaporized during spraying. If the heating and pressurizing step is performed at an excessively high temperature and pressure, the pressure may become too high to maintain the temperature, or the temperature of the vaporized lactic acid may be too high, resulting in the lactic acid molecules being converted into other substances.

[0088] From this viewpoint, the pretreatment section may further include a temperature control section and a pressure control section that heat and pressurize the lactic acid aqueous solution having the 1-1 concentration at a temperature of 150° C. to 250° C. and a pressure of 1 bar to 40 bar.

[0089] According to another embodiment of the invention, the temperature of the 1-1 stream, i.e., the temperature of the 1-1 stream to be sprayed, may be about 10 to about 300°C, preferably about 10°C or more, or about 50°C or more, or about 150°C or more, and may be about 300°C or less, or about 250°C or less, or about 200°C or less.

[0090] If the temperature of the 1-1 stream is too low outside the temperature range, there may be a problem that some of the vaporized lactic acid will condense, and if the temperature is too high, there may be a problem that the lactic acid molecules will be converted into other substances.

[0091] In view of this, the feed supplying unit may further include a feed temperature adjusting unit for adjusting the temperature of the 1-1 stream.

[0092] The aqueous lactic acid solution supplied from the feed is heated and then sprayed in droplet form into the vaporization reactor through a transfer line and a nozzle.

[0093] That is, according to another embodiment of the present invention, the spraying unit may include a 1-1 stream nozzle that sprays the 1-1 stream into the inside of the vaporization reactor.

[0094] According to another embodiment of the invention, the 1-1 stream is preferably sprayed at a flow rate of about 0.1 g / min to 1.0 g / min, preferably at a flow rate of about 0.1 g / min or more, or about 0.15 g / min or more, and about 1.0 g / min or less, or about 0.5 g / min or less, or about 0.3 g / min or less.

[0095] If the spray amount and spray rate of the 1-1 stream are too low outside the above range, the flow rate of the lactic acid supplied will be too low, which may cause a problem of over-reaction in the dehydration reaction carried out as the next step. If they are too high, the heat required for vaporization will be too high, which may cause a problem of incomplete vaporization.

[0096] In addition, the 1-2 stream containing high-temperature steam can be sprayed into the vaporization reactor through a transfer line and nozzle separate from the 1-1 stream, i.e., the 1-1 stream and the 1-2 stream are preferably mixed and sprayed together into the vaporization reactor.

[0097] In view of this, according to another embodiment of the invention, the lactic acid vaporization device may further include a water vapor supply unit that supplies water vapor, and the spray unit may further include a 1-2 stream nozzle that receives water vapor from the water vapor generator and sprays a 1-2 stream of gas phase containing water vapor.

[0098] In this case, the high-temperature steam supplied to the 1-2 stream is mixed with the lactic acid supplied to the 1-1 stream, which can instantly dilute the lactic acid to a lower concentration, and additionally transfer heat energy to the lactic acid molecules to quickly reduce the oligomer content in the lactic acid and help the lactic acid molecules to vaporize.

[0099] During the mixed spraying, the transfer lines of the 1-1 stream and the 1-2 stream may be joined together before spraying and then mixed and sprayed through the same nozzle. However, it is more preferable that the 1-1 stream and the 1-2 stream are mixed and sprayed into the gasification reactor through separate nozzles.

[0100] From this viewpoint, the temperature of the 1-2 stream may be about 200 to about 600°C, preferably about 250°C or more, or about 300°C or more, or about 350°C or more, or about 400°C or more, and may be about 600°C or less, or about 550°C or less, or about 530°C or less.

[0101] At this time, the temperature difference between the 1-2 stream and the 1-1 stream is preferably about 200° C. or more, or about 250° C. or more, and about 500° C. or less, or about 450° C. or less.

[0102] If the temperature of the 1-2 stream is too low outside the above range, the temperature of the mixture may be too low, causing insufficient vaporization of lactic acid. If the temperature of the 1-2 stream is too high outside the above range, the pressure may become too high to maintain the temperature.

[0103] In view of this, the steam supplying unit may further include a steam temperature adjusting unit for adjusting the temperature of the first and second streams.

[0104] It is preferable that the 1-2 stream is sprayed at a flow rate of 0.1 g / min to 3.0 g / min, preferably at a flow rate of about 0.1 g / min or more, or about 0.2 g / min or more, or about 0.3 g / min or more, and about 3.0 g / min or less, or about 2.0 g / min or less, or about 1.0 g / min or less.

[0105] If the spray amount and spray rate of the first and second streams are too low outside the above range, the heat supplied to the vaporization is reduced, which may cause a problem of incomplete vaporization. If the spray amount and spray rate are too high, the concentration of lactic acid is diluted, which may cause a problem in the subsequent product separation process.

[0106] At this time, in the mixing and spraying step, the flow rate of the 1-1 stream: the flow rate of the 1-2 stream is preferably about 1:1.5 to about 1:5.

[0107] According to another embodiment of the invention, it is preferable to preliminarily saturate the inside of the vaporization reactor with water vapor before the 1-1 stream and the 1-2 stream are mixed and sprayed in the form of droplets into the vaporization reactor through the transfer line and the nozzle, respectively.

[0108] This method can prevent water from evaporating and concentrating lactic acid in droplets of the 1-1 stream that is instantly sprayed under high temperature conditions when the 1-1 stream is sprayed inside the reactor under high temperature conditions.

[0109] In this case, it is preferable to carry out the reaction in the vaporization reactor while maintaining the temperature at about 300 to about 400°C.

[0110] Meanwhile, the present invention provides a method for producing acrylic acid, comprising: obtaining lactic acid molecules by vaporizing lactic acid according to the above-mentioned method; producing acrylic acid by dehydrating the lactic acid molecules; and obtaining acrylic acid.

[0111] The reaction of producing acrylic acid by intramolecular dehydration of lactic acid is represented by the following chemical formula, and is known to occur in one step in the presence of a catalyst. [ka]

[0112] However, in the case of the method for producing acrylic acid according to one aspect of the present invention, except for the content related to the vaporization of lactic acid described above, the method for producing acrylic acid from vaporized lactic acid may use a catalyst, a reactor, or reaction conditions generally known in the technical field to which the present invention pertains.

[0113] For example, catalysts used in the lactic acid dehydration reaction include CaSO4 / Na2SO4; Na4P2O7 / CaSO4; Na4P2O7 / Ca3(PO4)2; NaH2PO4-NaHCO3 / SiO2; AlPO4-NH3; Ca3(PO4)2 / CaSO4, etc.

[0114] The dehydration reaction using a solid catalyst can be carried out by a continuous reaction using a fixed reactor, a batch reaction, etc. When a fixed reactor is used, the reactor is filled with a solid catalyst and reactants are continuously supplied to the reactor for reaction, thereby continuously producing a product.

[0115] The temperature of the dehydration reaction may be about 300 to about 500° C., or about 350 to about 450° C. The reaction pressure may be about 1 atm to about 5 atm, or about 1 atm to about 2 atm.

[0116] The supply rate of the reactants varies depending on the type and shape of the reactor, different reaction conditions, etc., but specifically, for example, the supply rate of gas-phase lactic acid (Weight Hourly Space Velocity, WHSV) may be about 0.05 to about 1.0 / hr, or about 0.10 to about 0.50 / hr.

[0117] If the above conditions are not met, a cracking reaction due to hydrogenation may occur, resulting in a decrease in reaction efficiency or a low conversion rate.

[0118] Meanwhile, according to another aspect of the present invention, there is provided a method for vaporizing lactic acid, comprising the steps of: mixing and spraying a 3-1 stream in a liquid phase containing an aqueous lactic acid solution and a 3-2 stream in a gas phase containing water vapor; vaporizing the aqueous lactic acid solution by heat exchange between the 3-1 stream and the 3-2 stream; and obtaining a 3-3 stream in a gas phase containing lactic acid monomers.

[0119] According to another aspect of the present invention, there is provided a lactic acid vaporization apparatus including a feed supply unit 100 for supplying a 3-1 stream containing an aqueous lactic acid solution; a steam supply unit 200 for supplying a 3-2 stream containing water vapor; a vaporization reaction unit 300 for receiving the 3-1 stream from the feed supply unit and the 3-2 stream from the steam supply unit and performing a vaporization reaction of the aqueous lactic acid solution; and a collection unit 400 for collecting a 3-3 stream containing vaporized lactic acid molecules.

[0120] When the above-mentioned apparatus is used, a method for vaporizing lactic acid can be realized, which includes the steps of: mixing and spraying a 3-1 stream in a liquid phase containing an aqueous lactic acid solution and a 3-2 stream in a gas phase containing water vapor; vaporizing the aqueous lactic acid solution by heat exchange between the 3-1 stream and the 3-2 stream; and obtaining a 3-3 stream in a gas phase containing lactic acid monomers.

[0121] The inventors of the present invention discovered that when a highly concentrated aqueous lactic acid solution is mixed and sprayed with water vapor and vaporized by direct heat exchange, the oligomer concentration of lactic acid can be efficiently reduced in a very short time, and thus completed the present invention.

[0122] Lactic acid is often used in the production of acrylic acid, but when lactic acid is dehydrated to produce acrylic acid, the process is carried out by a gas phase reaction, so it is necessary to vaporize the lactic acid into lactic acid molecules.

[0123] However, as mentioned above, lactic acid is usually stored at a high concentration during storage and distribution after production, and due to the structural characteristics of the lactic acid molecule, which contains both hydroxyl and carboxyl groups within the molecule, it often forms a dimer structure or an oligomer in the form of dehydration condensation due to the removal of water molecules.

[0124] Such lactic acid oligomer molecules can be carbonized in the vaporization or reaction stage to form coke, reducing the active area of ​​the reaction catalyst, and can also be included as a by-product in the final product. Above all, the presence of lactic acid oligomers significantly reduces the content of monomolecular lactic acid that can participate in the reaction. Therefore, it is necessary to convert the lactic acid oligomers into monomolecular forms in the concentrated lactic acid aqueous solution to reduce the oligomer content and increase the content of monomolecular lactic acid.

[0125] However, when water is simply added to a concentrated aqueous lactic acid solution containing a high content of lactic acid oligomers to dilute the concentration, the equilibrium shift rate is very slow, so it takes a very long time to reduce the content of lactic acid oligomers.

[0126] In general, to shorten this time, a high-concentration aqueous lactic acid solution of about 80 wt% or more is heated and vaporized, but since the vaporization efficiency of lactic acid is lower than that of water, water vaporizes first and the ratio of lactic acid in the gas phase falls below about 20 wt%. In this case, the concentration of the remaining aqueous lactic acid solution becomes higher because water vaporizes first, and therefore the concentration of oligomers in the remaining aqueous lactic acid solution also increases, which creates a problem that requires an additional treatment process.

[0127] Therefore, the method for vaporizing lactic acid according to an aspect of the present invention includes the steps of mixing and spraying a 3-1 stream in a liquid phase containing an aqueous lactic acid solution and a 3-2 stream in a gas phase containing water vapor; vaporizing the aqueous lactic acid solution by heat exchange between the 3-1 stream and the 3-2 stream; and obtaining a 3-3 stream in a gas phase containing lactic acid monomers.

[0128] The vaporization apparatus for lactic acid according to one aspect of the present invention includes a feed supply unit 100 for supplying a 3-1 stream containing an aqueous lactic acid solution; a steam supply unit 200 for supplying a 3-2 stream containing water vapor; a vaporization reaction unit 300 for receiving the 3-1 stream from the feed supply unit and the 3-2 stream from the steam supply unit and performing a vaporization reaction of the aqueous lactic acid solution; and a collection unit 400 for collecting a 3-3 stream containing vaporized lactic acid molecules.

[0129] FIG. 1 is a schematic diagram showing a lactate vaporizer according to one embodiment of the present invention.

[0130] Referring to FIG. 1, one embodiment of a lactic acid vaporization apparatus can be seen, which includes a feed supply unit 100 for supplying a 3-1 stream containing an aqueous lactic acid solution; a steam supply unit 200 for supplying a 3-2 stream containing water vapor; a vaporization reaction unit 300 for receiving the 3-1 stream from the feed supply unit and the 3-2 stream from the steam supply unit and performing a vaporization reaction of the aqueous lactic acid solution; and a collection unit 400 for collecting a 3-3 stream containing vaporized lactic acid molecules.

[0131] That is, according to one embodiment of the present invention, instead of directly heating and vaporizing a high-concentration lactic acid aqueous solution, a high-concentration lactic acid aqueous solution is sprayed in the form of an aerosol, and high-temperature steam is mixed and sprayed thereto to reduce the concentration of lactic acid. At the same time, the lactic acid is vaporized by rapid heat exchange between the high-concentration lactic acid sprayed in the form of an aerosol and the steam, thereby obtaining vaporized lactic acid monomolecules.

[0132] The concentration of lactic acid in the 3-3 stream may be about 30 wt% or less, or about 25 wt% or less, or about 20 wt% or less, and although the lower limit may not be significant depending on the process conditions, it may be about 0.1 wt% or more, or about 5 wt% or more.

[0133] More specifically, the 3-3 stream containing lactic acid monomers herein may contain, for example, the above-mentioned lactic acid oligomers at less than about 1 wt%, preferably less than about 0.5 wt%, or less than about 0.1 wt%, and more preferably is substantially free of lactic acid oligomers.

[0134] Being substantially free of lactic acid oligomers means that the content of lactic acid oligomers is 0 wt % within the limits detectable in the relevant process.

[0135] According to one embodiment of the invention, the lactic acid aqueous solution contained in stream 3-1 may have a lactic acid concentration of about 40 to about 99 wt%, about 45 wt% or more, or about 50 wt% or more, or about 60 wt% or more, or about 70 wt% or more, or about 75 wt% or more, and may be highly concentrated, such as about 99 wt% or less, about 95 wt% or less, or about 90 wt% or less, or about 85 wt% or less.

[0136] The concentration of polymers in the aqueous lactic acid solution contained in the 3-1 stream, i.e., the concentration of lactic acid dimers or lactic acid oligomers of trimers or higher, may be about 2 to about 55 wt%, or about 2 wt% or more, or about 5% or more, or about 7 wt% or more, or about 8 wt% or more, and may be about 55 wt% or less, or about 40 wt% or less, or about 20 wt% or less, i.e., the content of polymers is relatively high.

[0137] Here, the lactic acid aqueous solution contained in the 3-1 stream, i.e., the lactic acid feed in the process, is in a state in which lactic acid is dissolved in water, and as described above, it naturally means a state in which lactic acid monomolecules, lactic acid dimers, and lactic acid oligomers are all contained depending on the temperature and concentration conditions, and the lactic acid concentration described here also means the concentration of lactic acid-based compounds including not only lactic acid monomolecules but also lactic acid monomolecules, lactic acid dimers, and lactic acid oligomers.

[0138] More specifically, for example, when calculated by computer modeling based on the known oligomerization equilibrium constant value of lactic acid, the oligomer content according to the concentration of all lactic acid-based compounds is as shown in Table 2 below.

[0139] However, there may be some calculation errors depending on the actual calculation model, and the actual measured values ​​may also have some measurement errors depending on the measurement conditions and measurement method (titration method or HPLC). [Table 2]

[0140] Then, the aqueous lactic acid solution supplied from the feed (stream 3-1) undergoes a heating process.

[0141] To this end, the feed supply section can include an aqueous lactic acid solution feed 110 for supplying an aqueous lactic acid solution; and a feed pre-treatment section 120 for adjusting the temperature and pressure of the 3-1 stream.

[0142] At this time, the feed pre-treatment unit 120 can adjust the temperature of the 3-1 stream to about 10 to about 300° C. and the pressure to 1 to 50 atm before discharging it.

[0143] More specifically, the temperature of the 3-1 stream discharged from the feed pre-treatment section may be about 10 to about 300°C, preferably about 10°C or more, or about 15°C or more, or about 50°C or more, and may be about 300°C or less, or about 250°C or less, or about 200°C or less.

[0144] If the temperature of the 3-1 stream is too low outside the temperature range, the temperature of the mixture may be too low and the lactic acid may not be sufficiently vaporized. If the temperature is too high, the pressure may become too high to maintain the temperature.

[0145] The aqueous lactic acid solution supplied from the feed is heated and then sprayed in the form of droplets into the vaporization reactor through a transfer line and a nozzle. The higher the temperature of the aqueous lactic acid solution is maintained and the higher the pressure is, the more advantageous it is to obtain smaller droplets.

[0146] At this time, in addition to the 3-1 stream, the 3-2 stream containing water vapor is also mixed and sprayed in the form of droplets together with the 3-1 stream into the vaporization reactor through the transfer line and the nozzle.

[0147] During the mixed spraying, the transfer lines of the 3-1 stream and the 3-2 stream may be joined together before spraying and then mixed and sprayed through the same nozzle. However, it is more preferable that the 3-1 stream and the 3-2 stream are mixed and sprayed into the gasification reactor through separate nozzles.

[0148] For this purpose, the vaporization reaction unit 300 may include a spray unit 310 at its lower end, which sprays the 3-1 stream supplied from the feed supply unit and the 3-2 stream supplied from the steam supply unit into the vaporization reaction unit.

[0149] In the spray section, the 3-1 stream and the 3-2 stream can be i) combined in a pre-spray stage and mixed and sprayed into the inside of the vaporization reaction section, ii) combined in a single nozzle in the spray stage and mixed and sprayed into the inside of the vaporization reaction section, or iii) mixed and sprayed into the inside of the vaporization reaction section through a separate nozzle.

[0150] That is, the spraying section can include a mixing spray nozzle that mixes and sprays the 3-1 stream and the 3-2 stream.

[0151] According to another example, the spraying section can include a 3-1 nozzle for spraying a 3-1 stream and a 3-2 nozzle for spraying a 3-2 stream.

[0152] However, in order to prevent the concentration of the lactic acid aqueous solution from decreasing during the transfer process, it is more preferable that the 3-1 stream and the 3-2 stream are mixed and sprayed into the vaporization reactor through separate nozzles.

[0153] The 3-2 stream instantly reduces the concentration of lactic acid in the 3-1 stream, which contains highly concentrated lactic acid, and at the same time transfers thermal energy to the 3-1 stream, promoting the vaporization of lactic acid molecules and reducing the proportion of oligomers.

[0154] From this viewpoint, the temperature of the 3-2 stream may be about 200 to about 600°C, preferably about 250°C or more, or about 300°C or more, or about 350°C or more, or about 400°C or more, and may be about 600°C or less, or about 550°C or less, or about 530°C or less.

[0155] To this end, the water vapor supply may include a water supply 210 for supplying water; and a water pretreatment section 220 for adjusting the temperature and pressure of the 3-2 stream.

[0156] The water pre-treatment section 220 can adjust the temperature and pressure of the 3-2 stream to the above-mentioned range of about 1 to 10 atm before discharging the stream.

[0157] The temperature difference between the 3-2 stream and the 3-1 stream is preferably about 200° C. or more, or about 250° C. or more, and about 500° C. or less, or about 450° C. or less.

[0158] If the temperature of the 3-2 stream is too low outside the above range, the temperature of the mixture may be too low and the lactic acid may not be sufficiently vaporized. If the temperature of the 3-2 stream is too high outside the above range, the pressure may become too high to maintain the temperature.

[0159] According to another embodiment of the invention, the 3-1 stream can be sprayed at a flow rate of 0.05 g / min to 1.5 g / min, with the lower limit being preferably about 0.05 g / min or more, or about 0.1 g / min or more, or about 0.15 g / min or more, or about 0.18 g / min or more, and the upper limit being preferably about 1.5 g / min or less, or about 1.0 g / min or less, or about 0.8 g / min or less.

[0160] If the spray amount and spray rate of the 3-1 stream are too low outside the above range, the flow rate of the lactic acid supplied will be too low, which may cause an over-reaction in the dehydration reaction carried out in the next step. If the spray amount and spray rate are too high, the heat required for vaporization will be too high, which may cause incomplete vaporization.

[0161] The 3-2 stream can be sprayed at a flow rate of 0.1 g / min to 4.0 g / min, with the lower limit being preferably about 0.1 g / min or more, or about 0.2 g / min or more, or about 0.3 g / min or more, and the upper limit being preferably about 4.0 g / min or less, or about 3.0 g / min or less, or about 2.0 g / min or less.

[0162] If the spray amount and spray rate of the 3-2 stream are too low outside the above range, the heat supplied to the vaporization is reduced, which may cause incomplete vaporization. If the spray amount and spray rate are too high, the concentration of lactic acid may be diluted, which may cause problems in the subsequent product separation process.

[0163] In the mixing and spraying step, the flow rate of the 3-1 stream:the flow rate of the 3-2 stream is preferably about 1:1.5 to about 1:5.

[0164] If the flow rate ratio of the 3-1 stream is too small outside the above range, the flow rate of the lactic acid supplied is low, which may result in low efficiency and a problem of heavy load during the product separation process. If the flow rate ratio of the 3-2 stream is too small, the heat supplied to the vaporization is low, which may result in incomplete vaporization.

[0165] According to another embodiment of the invention, it is preferable that the inside of the vaporization reactor is saturated with water vapor before the 3-1 stream and the 3-2 stream are mixed and sprayed in the form of droplets into the vaporization reactor through a transfer line and a nozzle, respectively.

[0166] In this manner, when the 3-1 stream is sprayed into the reactor at high temperature, it is possible to prevent water from evaporating and lactic acid from being concentrated in the droplets of the 3-1 stream that is sprayed instantly at high temperature.

[0167] In this case, it is preferable to carry out the reaction in the vaporization reactor while maintaining the temperature condition of about 150 to about 250°C.

[0168] The acquisition unit may be located above the vaporization reaction unit.

[0169] After the 3-1 and 3-2 streams supplied to the lower part of the vaporization reaction section are mixed and sprayed, the lactic acid aqueous solution contained in the 3-1 stream is instantly vaporized, and the lactic acid monomolecules generated move to the collection section at the upper part of the vaporization reaction section.

[0170] The collecting unit may include a gas-liquid separator 410 that separates and discharges the vaporized lactic acid molecules and the liquefied aqueous solution components.

[0171] At this time, the aqueous solution component discharged from the gas-liquid separator can be recovered in the aqueous lactic acid solution feed 110 and reused.

[0172] Meanwhile, the present invention provides a method for producing acrylic acid, comprising: obtaining lactic acid molecules by vaporizing lactic acid using any one of the above methods; producing acrylic acid by dehydrating the lactic acid molecules; and obtaining acrylic acid.

[0173] The reaction of producing acrylic acid by intramolecular dehydration of lactic acid can be represented by the following chemical formula, and is known to occur in one step in the presence of a catalyst. [ka]

[0174] However, in the case of the method for producing acrylic acid according to one aspect of the present invention, except for the content related to the vaporization of lactic acid described above, the method for producing acrylic acid from vaporized lactic acid may use a catalyst, a reactor, or reaction conditions generally known in the technical field to which the present invention pertains.

[0175] For example, catalysts used in the lactic acid dehydration reaction include CaSO4 / Na2SO4; Na4P2O7 / CaSO4; Na4P2O7 / Ca3(PO4)2; NaH2PO4-NaHCO3 / SiO2; AlPO4-NH3; Ca3(PO4)2 / CaSO4, etc.

[0176] The dehydration reaction using a solid catalyst can be carried out by a continuous reaction using a fixed reactor, a batch reaction, etc. When a fixed reactor is used, the reactor is filled with a solid catalyst and reactants are continuously fed to the reactor to react, thereby continuously producing a product.

[0177] The temperature of the dehydration reaction may be about 300 to about 500° C., or about 300 to about 400° C. The reaction pressure may be about 1 atm to about 5 atm, or about 1 atm to about 2 atm.

[0178] The supply rate of the reactants varies depending on the type and shape of the reactor, different reaction conditions, etc., but specifically, for example, the supply rate of lactic acid in the gas phase (Weight Hourly Space Velocity, WHSV) can be about 0.05 to about 1.0 / hr, or about 0.10 to about 0.50 / hr.

[0179] If the above conditions are not met, a cracking reaction due to oligomerization or hydrogenation may occur, resulting in a decrease in reaction efficiency or a low conversion rate. Effect of the Invention

[0180] According to the method and apparatus for vaporizing lactic acid according to one aspect of the present invention, the content of lactic acid oligomers can be reduced and the content of lactic acid monomolecules can be increased in a short period of time in a highly concentrated aqueous lactic acid solution. [Brief description of the drawings]

[0181] [Figure 1] FIG. 1 is a schematic diagram showing a lactate vaporizer according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0182] The functions and effects of the present invention will be described in more detail below with reference to specific examples of the present invention. However, these examples are presented only as examples of the present invention and do not define the scope of the invention.

[0183] <First Example> An aqueous solution of lactic acid with a concentration of about 80 wt % was prepared. In the pretreatment section, the aqueous lactic acid solution was heated and pressurized at 180° C. and 10 atm to prepare for supply to the feed. [Table 3]

[0184] The concentration of the aqueous lactic acid solution, i.e., the feed containing all of lactic acid, lactic acid dimers, and lactic acid oligomers, was determined by taking a sample of each solution, measuring the carbon content by elemental analysis, and dividing the carbon content by the carbon content ratio in lactic acid.

[0185] The ratio of lactic acid oligomers (including dimers) in the lactic acid aqueous solution was calculated by taking each sample, analyzing the content of monomolecular lactic acid using HPLC, and then dividing the amount of oligomers by the total amount of lactic acid-based compounds based on the concentration of the lactic acid aqueous solution and the content of monomolecular lactic acid.

[0186] A lactic acid vaporization apparatus was prepared, which included a feed supply unit for supplying a 1-1 stream containing the aqueous lactic acid solution; a steam supply unit for supplying a 1-2 stream containing water vapor; a spray unit in which the aqueous lactic acid solution transferred from the feed supply unit and the water vapor transferred from the steam supply unit are mixed and sprayed through their respective nozzles; a vaporization reaction unit in which the aqueous lactic acid solution is vaporized after being mixed and sprayed; and a collection unit for collecting a 1-3 stream containing vaporized lactic acid molecules.

[0187] The feed supply section and steam supply section were equipped with a thermometer and a temperature controller to adjust the temperature of the feed (stream 1-1) and steam (stream 1-2) supplied, and the harvesting section was equipped with a thermometer to measure the temperature of stream 1-3.

[0188] First, water vapor was introduced into the vaporization reactor so that the inside of the vaporization reactor was saturated with water vapor.

[0189] Thereafter, the aqueous lactic acid solution according to Examples 1 to 7 was supplied to the 1-1 stream by the feed supply unit, and water vapor was supplied by the water vapor supply unit so that the aqueous lactic acid solution was continuously mixed and sprayed into the inside of the vaporization reaction unit through the respective nozzles, and the 1-3 stream containing vaporized lactic acid molecules was obtained by the collection unit.

[0190] The spray conditions are summarized in Table 4 below. [Table 4]

[0191] The obtained streams 1-3 were analyzed, and the concentration of all lactic acid-based compounds in the streams 1-3 and the ratio of oligomers therein were measured and calculated, and are summarized in Table 5 below. [Table 5]

[0192] Referring to Table 5, it can be clearly seen that, according to the embodiment of the present invention, the content of lactic acid oligomers can be reduced in a very short time by continuously vaporizing lactic acid.

[0193] <Second Example> Separately, an aqueous solution of lactic acid was prepared with the concentrations summarized in Table 6 below. [Table 6]

[0194] The concentration of the aqueous lactic acid solution, i.e., the feed containing all of lactic acid, lactic acid dimers, and lactic acid oligomers, was determined by taking a sample of each solution, measuring the carbon content by elemental analysis, and dividing the carbon content by the carbon content ratio in lactic acid.

[0195] The ratio of lactic acid oligomers (including dimers) in the lactic acid aqueous solution was calculated by taking each sample, analyzing the content of monomolecular lactic acid using HPLC, and then dividing the amount of oligomers by the total amount of lactic acid-based compounds based on the concentration of the lactic acid aqueous solution and the content of monomolecular lactic acid.

[0196] A lactic acid vaporization apparatus having the configuration illustrated in FIG. 1 was prepared, which included a feed supplying section for supplying a 3-1 stream containing the aqueous lactic acid solution; a steam supplying section for supplying a 3-2 stream containing steam; a spraying section in which the aqueous lactic acid solution transferred from the feed supplying section and the steam transferred from the steam supplying section are mixed and sprayed through their respective nozzles; a vaporization reaction section in which the aqueous lactic acid solution is vaporized after being mixed and sprayed; and a collection section for collecting a 3-3 stream containing vaporized lactic acid molecules.

[0197] The feed supply section and steam supply section were equipped with a thermometer and a temperature controller to adjust the temperature of the feed (stream 3-1) and steam (stream 3-2) supplied, and the harvesting section was equipped with a thermometer to measure the temperature of stream 3-3.

[0198] First, water vapor was introduced into the vaporization reactor so that the inside of the vaporization reactor was saturated with water vapor.

[0199] Thereafter, the aqueous lactic acid solution according to Examples 1 to 7 was supplied to the 3-1 stream by the feed supply unit, and water vapor was supplied by the water vapor supply unit so that the aqueous lactic acid solution was continuously mixed and sprayed into the vaporization reaction unit through the respective nozzles, and the 3-3 stream containing vaporized lactic acid molecules was obtained by the collection unit.

[0200] The spray conditions are summarized in Table 7 below. [Table 7]

[0201] The obtained 3-3 stream was analyzed, and the concentration of all lactic acid-based compounds in the 3-3 stream and the ratio of oligomers therein were measured and calculated, and are summarized in Table 8 below. [Table 8]

[0202] Referring to Table 8, it can be clearly seen that, according to the embodiment of the present invention, the content of lactic acid oligomers can be reduced in a very short time by continuously vaporizing lactic acid. [Explanation of symbols]

[0203] 1. Stream 3-1 2. Stream 3-2 3. 3rd-3rd Stream 100 Feed supply section 110 Lactic acid aqueous solution feed 120 Feed pre-processing section 200 Steam supply section 210 Water supply section 220 Water pretreatment section 300 Vaporization reaction section 310 Spray section 400 Acquisition Department 410 Gas-liquid separator 111,121,211,221 Flow regulator (valve)

Claims

1. A step of heating and pressurizing the lactic acid aqueous solution having the 1-1 concentration; spraying a 1-1 stream of a liquid phase containing the heated and pressurized aqueous lactic acid solution having a 1-1 concentration; vaporizing the lactic acid contained in the 1-1 stream by spraying; and A method for vaporizing lactic acid, comprising the steps of obtaining first to third streams of a vapor phase comprising lactic acid molecules.

2. 2. The method of claim 1, wherein the step of heating and pressurizing the lactic acid aqueous solution having the 1-1 concentration is performed at a temperature of 150° C. to 250° C. and a pressure of 1 bar to 40 bar.

3. The lactic acid vaporization method according to claim 1, wherein the 1-1 concentration is 20 to 99 wt %.

4. 2. The method of claim 1, wherein the temperature of the 1-1 stream is between 10°C and 300°C.

5. 2. The method of claim 1, wherein the 1-1 stream is atomized at a flow rate of 0.1 g / min to 1.0 g / min.

6. 2. The method for vaporizing lactic acid according to claim 1, wherein the first-1 stream and a first-2 stream in a gas phase containing water vapor are mixed and sprayed when the first-1 stream is sprayed.

7. 7. The method for vaporizing lactic acid according to claim 6, wherein the temperature of the first and second streams is 200 to 600°C.

8. 7. The method of claim 6, wherein the first and second streams are atomized at a rate of 0.1 g / min to 3.0 g / min.

9. 7. The method for vaporizing lactic acid according to claim 6, wherein the flow rate of the first-1 stream: the flow rate of the first-2 stream is 1:1.5 to 1:5 in the mixing and spraying step.

10. 11. The method of claim 1, further comprising the steps of: vaporizing lactic acid to obtain lactic acid molecules; Dehydrating the lactic acid molecules to produce acrylic acid; and The method for producing acrylic acid includes obtaining the acrylic acid.

11. a pretreatment section for heating and pressurizing the lactic acid aqueous solution having a 1-1 concentration; a feed supply unit that receives the aqueous lactic acid solution from the pretreatment unit and supplies a 1-1 stream containing the aqueous lactic acid solution; a spraying section for spraying the 1-1 stream transferred from the feed supply section into the vaporization reactor; A lactic acid vaporizer including: a vaporization reactor in which the sprayed lactic acid aqueous solution is vaporized; and a collection section for collecting first to third streams containing vaporized lactic acid molecules.

12. The lactic acid vaporization device according to claim 11, wherein the pretreatment unit further includes a temperature control unit and a pressure control unit that heat and pressurize the lactic acid aqueous solution having the 1-1 concentration at a temperature of 150°C to 250°C and a pressure of 1 bar to 40 bar.

13. 13. The lactic acid vaporizer according to claim 11, wherein the 1-1 concentration is 20 to 99 wt %.

14. 12. The lactic acid vaporizer of claim 11, wherein the feed supply unit further comprises a feed temperature controller that adjusts the temperature of the 1-1 stream to 150 to 300°C.

15. The lactic acid vaporization device according to claim 11, wherein the spraying unit includes a 1-1 stream nozzle that adjusts the 1-1 stream to be sprayed at a flow rate of 0.1 g / min to 1.0 g / min.

16. The lactate vaporizer further includes a water vapor supply unit for supplying water vapor, 12. The lactic acid vaporization apparatus of claim 11, wherein the spraying unit further comprises a first-second stream nozzle configured to receive water vapor from the water vapor generator and spray a first-second stream of a gas phase containing water vapor into the vaporization reactor.

17. 17. The lactic acid vaporizer of claim 16, wherein the steam supplying unit further comprises a steam temperature adjusting unit for adjusting the temperature of the first and second streams to 200 to 600.degree.

18. 17. The lactate vaporizer according to claim 16, wherein the first and second streams are adjusted in the spraying section so as to be sprayed at a flow rate of 0.1 g / min to 3.0 g / min.

19. 17. The lactic acid vaporizer according to claim 16, wherein the flow rate of the first-1 stream: the flow rate of the first-2 stream is adjusted to be 1:1.5 to 1:5 in the spray section.

20. A step of mixing and spraying a 3-1 stream of a liquid phase containing an aqueous lactic acid solution and a 3-2 stream of a gas phase containing water vapor; vaporizing the aqueous lactic acid solution by heat exchange between the 3-1 stream and the 3-2 stream; and A method for vaporizing lactic acid, comprising the step of obtaining a 3-3 stream of a vapor phase comprising monomeric lactic acid.

21. The method of claim 20, wherein the aqueous lactic acid solution contained in the 3-1 stream has a lactic acid concentration of 40 to 99 wt %.

22. The method for vaporizing lactic acid according to claim 20, wherein the concentration of polymers in the aqueous lactic acid solution contained in the 3-1 stream is 2 to 55 wt %.

23. 21. The method of claim 20, wherein the temperature of the 3-1 stream is from 10 to 300° C.

24. 21. The method of claim 20, wherein the temperature of the third-2 stream is 200 to 600° C.

25. 21. The method of claim 20, wherein the temperature difference between the 3-2 stream and the 3-1 stream is 200°C to 500°C.

26. 21. The method of claim 20, wherein the 3-1 stream is atomized at a rate of 0.05 g / min to 1.5 g / min.

27. 21. The method of claim 20, wherein the third-2 stream is atomized at a flow rate of 0.1 g / min to 4.0 g / min.

28. 21. The method for vaporizing lactic acid according to claim 20, wherein the flow rate of the 3-1 stream: the flow rate of the 3-2 stream is 1:1.5 to 1:5 in the mixing and spraying step.

29. 29. A step of vaporizing lactic acid by the method according to any one of claims 20 to 28 to obtain lactic acid molecules; Dehydrating the lactic acid molecules to produce acrylic acid; and The method for producing acrylic acid includes obtaining the acrylic acid.

30. a feed supply for providing a 3-1 stream comprising an aqueous lactic acid solution; a steam supply providing a 3-2 stream comprising steam; a vaporization reaction section which receives the 3-1 stream from the feed supply section and the 3-2 stream from the water vapor supply section and performs a vaporization reaction of the aqueous lactic acid solution; and a lactic acid vaporizer including a collection portion for collecting a 3-3 stream including vaporized lactic acid molecules;

31. The lactic acid vaporization apparatus according to claim 30, wherein the vaporization reaction section includes a spray section at a lower end thereof that sprays the 3-1 stream supplied from the feed supply section and the 3-2 stream supplied from the water vapor supply section into the inside of the vaporization reaction section.

32. The feed supply unit is a lactic acid aqueous solution feed that supplies an aqueous lactic acid solution; and 31. The lactic acid vaporizer of claim 30, comprising a feed pre-treatment section for adjusting the temperature and pressure of the 3-1 stream.

33. 33. The lactic acid vaporizer of claim 32, wherein the feed pre-treatment section discharges the 3-1 stream at a temperature of 10 to 300°C.

34. The water vapor supply unit is a water supply unit that supplies water; and 31. The lactic acid vaporizer of claim 30, comprising a water pretreatment section for adjusting the temperature and pressure of the 3-2 stream.

35. 35. The lactic acid vaporizer of claim 34, wherein the water pre-treater discharges the tertiary-second stream at a temperature of 200 to 600°C.

36. 32. The lactate vaporization apparatus according to claim 31, wherein the spraying section includes a mixing spray nozzle that mixes and sprays the 3-1 stream and the 2 stream.

37. The lactate vaporization device according to claim 31, wherein the spraying section includes a 3-1 nozzle that sprays the 3-1 stream and a 3-2 nozzle that sprays the 2nd stream.

38. The lactate vaporizer according to claim 31, wherein the ratio of the 3-1 stream spray flow rate to the 3-2 stream spray flow rate in the spray section is adjusted to be 1:1.5 to 1:

5.

39. The lactate gasification device according to claim 30, wherein the collection unit is located above the gasification reaction unit.

40. 31. The lactic acid vaporizer of claim 30, wherein the collecting unit includes a gas-liquid separator that separates and discharges the vaporized lactic acid molecules and the liquefied aqueous solution components.

41. 41. The lactic acid vaporizer according to claim 40, wherein the aqueous solution component discharged from the gas-liquid separator is recovered and reused as an aqueous lactic acid solution feed.

Images