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    • 专利摘要:
    PROCESS FOR CONTINUOUS ACRYLIC ACID (MET) RECOVERY AND PROCESS DEVICES This disclosure refers to a method of continuous recovery of (meth) acrylic acid and an apparatus used for the method of continuous recovery. The continuous (meth) acrylic acid recovery method according to the present invention can maintain a (meth) acrylic acid recovery rate equivalent to that of the previous recovery method, and can also significantly reduce energy consumption and minimize polymerization (meth) acrylic acid in the recovery process, thus providing improved operational stability.
    公开号:BR112015002422B1
    申请号:R112015002422-0
    申请日:2013-07-09
    公开日:2020-11-10
    发明作者:Se Won Baek；Jong Hun Song；Sul Hee Yoo
    申请人:Lg Chem, Ltd；
    IPC主号:
    专利说明:

    TECHNICAL FIELD
    [001] The present invention relates to a method of continuous (meth) acrylic acid recovery and an apparatus used for the method of continuous recovery. BACKGROUND OF THE TECHNIQUE
    [002] (Met) acrylic acid is generally prepared by oxidizing the gas phase of propane, propylene, (met) acrolein, and the like, in the presence of a catalyst. For example, propane, propylene, and the like, are converted to (meth) acrylic acid by means of (meth) acrolein by oxidation of the gas phase in the presence of an appropriate catalyst in a reactor, and mixed gas of the reaction product including acid ( met) unreacted acrylic, propane or propylene, (meth) acrolein, inert gas, carbon dioxide, water vapor, and various unreacted organic by-products (acetic acid, high-boiling by-products, and the like) are obtained in rear end of the reactor.
    [003] The mixed gas containing (meth) acrylic acid contacts an absorption solvent, such as process water and the like in an (meth) acrylic acid absorption tower, and is recovered as an aqueous (meth) acrylic acid solution. In addition, the insoluble gas removed from (meth) acrylic acid is recycled for a (meth) acrylic acid synthesis reaction, and part of it is incinerated, converted into harmless gas and discharged. The aqueous solution of (meth) acrylic acid is distilled and purified while passing through a water separation tower and the like, to obtain (meth) acrylic acid.
    [004] However, in order to improve the recovery efficiency of (meth) acrylic acid, several methods for controlling process conditions or process sequence and the like have been suggested. Among them, as a method for separating water and acetic acid from the aqueous solution of (meth) acrylic acid obtained in the absorption tower of (meth) acrylic acid, an azeotropic distillation method is known, in which the acetic acid, the main by-product of a (meth) acrylic acid process, is recovered from the top of the water separation tower, together with water using an azeotropic hydrophobic solvent in the water separation tower, and (met) acrylic acid is recovered from the bottom of the water separation tower.
    [005] In particular, the inventors suggested a method of recycling waste water containing acetic acid, which is recovered from the top of the water separation tower to the (meth) acrylic acid absorption tower and reuse it according to Korean patent open to the public Number 2009- 0041355.
    [006] The distillation method of an aqueous solution of (meth) acrylic acid using a hydrophobic, azeotropic solvent in the water separation tower can reduce the amount of residual water and at the same time effectively prevent the introduction of organic substances, and simplify the subsequent purification step.
    [007] However, the above method and the previously revealed (meth) acrylic acid recovery methods present problems, so a large amount of energy is consumed in the distillation process of an aqueous solution of (meth) acrylic acid, and normal operation cannot be performed due to the production of polymers by polymerization of (meth) acrylic acid, and thus, operational stability is reduced. DETAILED DESCRIPTION OF THE INVENTION Technical problem
    [008] It is an objective of the invention to provide a method of continuous recovery of (meth) acrylic acid that can greatly reduce energy consumption and still exhibit better operational stability.
    [009] It is another object of the invention to provide an apparatus for continuous recovery of (meth) acrylic acid. Technical Solution
    [010] According to one embodiment of the invention, a method of continuous recovery of (meth) acrylic acid is provided, including: contact of a mixed gas including (meth) acrylic acid, organic by-products and steam, which is produced by a reaction of synthesis of (meth) acrylic acid, with water in a (meth) acrylic acid absorption tower (100) to obtain an aqueous solution of (meth) acrylic acid; dividing and feeding the aqueous (meth) acrylic acid solution to a (meth) acrylic acid extraction tower (200) and a water separation tower (300); obtaining a (meth) acrylic acid extract with a reduced water content from the aqueous (meth) acrylic acid solution that is fed to the (meth) acrylic acid extraction tower (200), and feeding it to a water separation tower (300); and distillation of the aqueous (meth) acrylic acid solution and the (meth) acrylic acid extract which are fed to the water separation tower (300) to obtain (meth) acrylic acid.
    [011] The step of dividing and feeding the aqueous (meth) acrylic acid solution to a (meth) acrylic acid extraction tower (200) and a water separation tower (300) can be carried out in such a way that the 5 ~ 70% by weight of the aqueous (meth) acrylic acid solution obtained are fed to the (meth) acrylic acid extraction tower (200), and the remainder being fed to the water separation tower (300).
    [012] The (meth) acrylic acid synthesis reaction can be carried out by an oxidation reaction of at least one compound selected from the group consisting of propane, propylene, butane, isobutylene, f-butylene, and (met) acrolein in the presence of a gas phase catalyst.
    [013] Meanwhile, the internal temperature of the (meth) acrylic acid absorption tower (100) can be maintained at 50 to 100 ° C.
    [014] The phase of obtaining the aqueous (meth) acrylic acid solution can be conducted in such a way that an aqueous solution containing (meth) acrylic acid is discharged to the bottom of the (meth) acrylic acid absorption tower (100 ), and non-condensable gas devoid of (met) acrylic acid ((meth (acrylic acid-stripped non-condensable gas) is discharged at the top of the (met) acrylic acid absorption tower (100). In this case, the method for continuous recovery of (meth) acrylic acid according to the present invention may further include contacting the non-condensable gas with water to recover the acetic acid that is included in the non-condensing gas.
    [015] In water fed to the (meth) acrylic acid absorption tower (100), organic by-products can be included in a concentration of 3 to 20% by weight.
    [016] In the aqueous (meth) acrylic acid solution obtained from the (meth) acrylic acid absorption tower (100), (meth) acrylic acid can be included at a concentration of 40 to 90% by weight.
    [017] The (meth) acrylic acid extract can be obtained by contacting the aqueous (meth) acrylic acid solution that is fed to the (meth) acrylic acid extraction tower (200) with a hydrophobic extraction solvent to remove the water included in the aqueous solution.
    [018] The (meth) acrylic acid extract can be obtained from the top of the (meth) acrylic acid extraction tower (200) and fed to the water separation tower (300), and at least part of the lower liquid discharged from the (met) acrylic acid extraction tower (200) can be fed to the upper end of the (met) acrylic acid absorption tower (100) and used as a (met) acrylic acid absorption solvent. In the liquid discharged at the bottom of the (meth) acrylic acid extraction tower (200), (meth) acrylic acid can be included in a concentration of 5% by weight or less. The upper end of the (meth) acrylic acid absorption tower (100), in which at least part of the liquid discharged into the lower part of the (meth) acrylic acid absorption tower (200) is fed can be at least a point corresponding to a height of 70% or more of the lowest part of the absorption tower.
    [019] Distillation in the water separation tower (300) can be carried out in the presence of a hydrophobic, azeotropic solvent. Here, the hydrophobic, azeotropic solvent can include the same compound as the hydrophobic extraction solvent in the (meth) acrylic acid extraction tower (200).
    [020] By distillation in the water separation tower (300), discharged liquid including (meth) acrylic acid can be recovered from the bottom of the water separation tower (300), and the discharged liquid including a hydrophobic, azeotropic solvent, water and acetic acid can be recovered from the top of the water separation tower (300).
    [021] At that time, the liquid discharged from the top of the water separation tower (300) can be separated into an organic phase, including the azeotropic hydrophobic solvent and an aqueous layer, including acetic acid, at least part of the organic layer can be fed to the upper part of the water separation tower (300) as an azeotropic solvent, and at least part of the aqueous layer can be fed to the upper end of the (meth) acrylic acid absorption tower (100) as a solvent absorption.
    [022] In accordance with another embodiment of the invention, an apparatus for continuous recovery of (meth) acrylic acid is provided, including: an (meth) acrylic acid absorption tower (100) for contacting a gas mixture including organic by-products, steam, and (meth) acrylic acid, which is produced by a reaction of synthesis of (meth) acrylic acid, with water, to obtain an aqueous solution of (meth) acrylic acid; transfer tubes of aqueous solution of (meth) acrylic acid (102 and 103) which are connected, respectively, from the (meth) acrylic acid absorption tower (100) to a (meth) acrylic acid extraction tower ( 200) and a water separation tower (300), so that the aqueous solution of (meth) acrylic acid is divided and fed; a (meth) acrylic acid extraction tower (200) for obtaining (meth) acrylic acid extract with a reduced water content from the aqueous (meth) acrylic acid solution that is fed through the transfer tube aqueous (meth) acrylic acid solution (102), and feeding it to a water separation tower (300); a (meth) acrylic acid transfer piping (203) that is connected from the (meth) acrylic acid extraction tower (200) to a water separation tower (300), which the acid extract (met) acrylic is fed; and a water separation tower (300) for the distillation of an aqueous solution of (meth) acrylic acid fed through the transfer tubing of aqueous solution of (meth) acrylic acid (103), and extract of (meth) acrylic acid fed through the transfer tube of (meth) acrylic acid (203), to obtain (meth) acrylic acid. Advantageous effects
    [023] The continuous (meth) acrylic acid recovery method according to the present invention can maintain a recovery rate of (meth) acrylic acid equivalent to that of the previous recovery method, and can still significantly reduce energy consumption, being able to minimize the polymerization of (meth) acrylic acid in the recovery process, thus providing better operational stability.
    [024] Specifically, the method of continuous recovery of (meth) acrylic acid according to the present invention introduces a (meth) acrylic acid extraction tower (200) before a water separation tower (300) for distillation of an aqueous solution of (meth) acrylic acid in order to recover (meth) acrylic acid, thereby greatly reducing energy consumption in the water separation tower (300), thus improving the energy efficiency of the overall process.
    [025] In addition, the method according to the present invention divides and feeds the aqueous (meth) acrylic acid solution obtained from the (meth) acrylic acid absorption tower (100) to the acid extraction tower ( met) acrylic (200) and the water separation of the tower (300), thus reducing the capacity of the (met) acrylic acid extraction tower and the water separation tower, thus decreasing the installation, maintenance and simultaneously load , the treatment capacity of the aqueous (meth) acrylic acid solution fed from the (meth) acrylic acid absorption tower equivalent to that of the previous method, thus presenting high energy efficiency and improving productivity.
    [026] Furthermore, since the method of the present invention can effectively divide the treatment of the aqueous (meth) acrylic acid solution into the (meth) acrylic acid extraction tower (200) and the water separation tower (300 ), a load on the water separation tower (300) can be reduced, so that the temperature near the water inlet tower (300) feed inlet can be kept low, thus minimizing the polymerization of (meth) acrylic acid during distillation to provide better operational stability. BRIEF DESCRIPTION OF THE DRAWING
    [027] Figure 1 is a flow chart that schematically shows the method of continuous recovery of (meth) acrylic acid according to an embodiment of the invention. DETAILED DESCRIPTION OF THE MODALITIES
    [028] Hereinafter, the method of continuous recovery of (meth) acrylic acid and the recovery apparatus according to specific modalities of the invention will be explained.
    [029] Unless otherwise described, the terms used in this document are defined as follows.
    [030] First, "(meth) acrylic acid" generally refers to acrylic acid and / or methacrylic acid.
    [031] Secondly, 'mixed gas containing (meth) acrylic acid1 generally refers to a mixed gas that can be produced when (meth) acrylic acid is prepared by oxidation of the gas phase. That is, according to an embodiment of the invention, the mixed gas containing (meth) acrylic acid can be obtained by oxidizing the gas phase of at least one compound selected from the group consisting of propane, propylene, butane, / -butylene , f-butylene, and (meth) acrolein ("raw material compound") in the presence of a catalyst, where the mixed gas containing (meth) acrylic acid can include (meth) acrylic acid, the raw material compounds unreacted, (meth) acrolein, inert gas, carbon monoxide, carbon dioxide, water vapor and various organic by-products (acetic acid, high-boiling by-products and others) and the like.
    [032] As used herein, "low-boiling by-products" (light ends) or "high-boiling by-products" (heavy) are types of by-products that can be obtained in the acid preparation and recovery process (meth) acrylic, and generally refer to compounds that have a lower or greater molecular weight than (meth) acrylic acid.
    [033] The term "aqueous (meth) acrylic acid" refers to an aqueous solution in which (meth) acrylic acid is dissolved, and for example, the aqueous (meth) acrylic acid solution can be obtained by contact of mixed gas containing (meth) acrylic acid with water.
    [034] The term "(meth) acrylic acid extract" refers to an aqueous solution having a relatively higher concentration of (meth) acrylic acid than the aqueous (meth) acrylic acid solution, and for example, the extract (meth) acrylic acid can be obtained by reducing the water content included in the aqueous (meth) acrylic acid solution in a (meth) acrylic acid extraction tower (200).
    [035] Meanwhile, the technical terms used in this document are only to mention specific modalities, and are not intended to limit the invention.
    [036] Unique forms used in this document include plural forms, unless they have clearly opposite meanings.
    [037] The meaning of 'comprises' as used in this document is that of the specific property, area, integer, step, operation, element or component, and does not exclude the addition of other specific properties, areas, integers, steps, operations , elements or components.
    [038] Hereinafter, with reference to the accompanying drawings, specific modalities of the invention will be explained in detail, so that one skilled in the common technique can easily practice the same. However, the present invention can be accomplished in a number of ways, and is not limited to the examples.
    [039] The inventors had confirmed, during studies on the method of continuous recovery of (meth) acrylic acid that the previously disclosed recovery method of (meth) acrylic acid by means of azeotropic distillation presents problems, so that a large amount of energy it is consumed in a water separation tower (or distillation tower) for the distillation of an aqueous solution of (meth) acrylic acid, and operational stability is reduced due to the production of a polymer by polymerization of (meth) acrylic acid.
    [040] Therefore, the inventors confirmed during repeated studies to solve these problems that if a (meth) acrylic acid extraction tower (200) was introduced before a water separation tower (300) for the distillation of a solution aqueous (met) acrylic acid that is obtained in an (met) acrylic acid absorption tower (100), and in particular, if the aqueous (met) acrylic acid solution obtained in the (met) acrylic acid absorption tower (100) was divided and fed to the (met) acrylic acid extraction tower (200) and the water separation tower (300), as shown in figure 1, the energy efficiency of the total process could be improved. In addition, the inventors confirmed that the process in Figure 1 can effectively divide the load of the water separation tower (300), thereby minimizing a polymerization reaction of (meth) acrylic acid in a distillation process, providing better stability operational.
    [041] Thus, according to one embodiment of the invention, a method of continuous recovery of (meth) acrylic acid is provided, including: contacting a gas mixture including (meth) acrylic acid, organic by-products and steam, which is produced by a (meth) acrylic acid synthesis reaction with water in a (meth) acrylic acid absorption tower (100) to obtain an aqueous solution of (meth) acrylic acid; dividing and feeding the aqueous (meth) acrylic acid solution to a (meth) acrylic acid extraction tower (200) and a water separation tower (300); obtaining a (met) acrylic acid extract with a reduced water content from the aqueous (met) acrylic acid solution that is fed to the (met) acrylic acid extraction tower (200), and feeding it to a water separation tower (300); and distilling the aqueous (meth) acrylic acid solution and (meth) acrylic acid extract which are fed to the water separation tower (300) to obtain (meth) acrylic acid.
    [042] Hereinafter, with reference to figure 1, each step of the continuous (meth) acrylic acid recovery method according to the present invention will be explained.
    [043] First, the method of continuous recovery of (meth) acrylic acid according to the present invention includes a step of obtaining an aqueous solution of (meth) acrylic acid.
    [044] Since the aqueous solution of (meth) acrylic acid can be obtained by a common method in the technical field to which the invention belongs, the method is not specifically limited. However, according to the present invention, this step can be carried out by contacting a gas mixture including (meth) acrylic acid, organic by-products and steam, which is produced by a (meth) acrylic acid synthesis reaction with a absorption solvent in an (meth) acrylic acid absorption tower (100) to obtain an aqueous solution of (meth) acrylic acid.
    [045] In the present invention, the (meth) acrylic acid synthesis reaction can be carried out by an oxidation reaction of at least one compound selected from the group consisting of propane, propylene, butane, isobutylene, f-butylene, and (meth) acrolein in the presence of a gas phase catalyst.
    [046] The gas phase oxidation reaction can be advanced in a gas structure oxidation reactor of a common structure and under common reaction conditions. Common catalysts can be used as a gas phase oxidation reaction catalyst, and preferably the catalysts described in Korean Patent Nos. 0349602 and 037818, and the like can be used. However, the gas phase oxidation reaction is not limited to the examples mentioned above in the present invention.
    [047] In mixed gas containing (meth) acrylic acid produced by the gas phase oxidation reaction, the unreacted raw material compounds, intermediate (meth) acrolein, other inert gases, carbon dioxide, steam, and various by-products organic (acetic acid, low-boiling by-products, high-boiling by-products and the like) and others, in addition to the final (meth) acrylic acid product.
    [048] In accordance with the present invention, the mixed gas containing (meth) acrylic acid (1) can be fed to the (meth) acrylic acid absorption tower (100) and contacts the water of the absorption solvent and thus it is obtained in the form of an aqueous solution in which (meth) acrylic acid is dissolved.
    [049] The (meth) acrylic acid absorption tower (100) can be in the form of a filler column, including fillers such as Raschig rings, Pali rings, saddles, gauze, a structured filler, and the like , or a common multistage column, as well as to improve the contact efficiency of the mixed gas containing (meth) acrylic acid (1) with an absorption solvent.
    [050] In accordance with the present invention, mixed gas containing (meth) acrylic acid (1) can be fed to the bottom of the (meth) acrylic acid absorption tower (100) and an acid absorbing solvent (met ) acrylic included in the gas mixture (1) is fed to the upper part of the (meth) acrylic acid absorption tower (100).
    [051] The (meth) acrylic acid absorption solvent can be water, such as tap water, deionized water, and the like, and the absorption solvent can include process cycle water that is introduced from a process different. Thus, the absorption solvent can include a small amount of organic by-products (for example, acetic acid) introduced from a different process, and according to one embodiment of the invention, into the absorption solvent fed to the acid absorption tower ( met) acrylic (100), organic by-products can be included in a concentration of 3 to 20% by weight.
    [052] That is, considering the absorption efficiency of (met) acrylic acid in the (met) acrylic acid absorption tower (100), it is preferable that the absorption solvent (in particular, the process water cycle) fed the (meth) acrylic acid absorption tower (100) includes 20% by weight or less of organic by-products.
    [053] Meanwhile, the (meth) acrylic acid absorption tower (100) can be operated at an internal pressure of 1 to 1.5 bar, preferably 1 to 1.3 bar, considering the condensation condition (meth) acrylic acid and the moisture content condition according to the saturated water vapor pressure, and the like; and the internal temperature of the (meth) acrylic acid absorption tower (100) can be controlled from 50 to 100 ° C, preferably 50 to 80 ° C.
    [054] Through the above process, an aqueous (meth) acrylic acid solution is discharged to the bottom of the (meth) acrylic acid absorption tower (100), and non-condensable gas devoid of (meth) acrylic acid can be discharged to the upper part of the (meth) acrylic acid absorption tower (100).
    [055] Here, it is advantageous, in terms of improving the efficiency of the process, that the aqueous solution of (meth) acrylic acid which is discharged to the bottom of the (meth) acrylic acid absorption tower (100) includes acid ( met) acrylic at a concentration of 40 to 90% by weight, preferably 50 to 90% by weight, and more preferably 50 to 80% by weight.
    [056] Meanwhile, at least a part of the non-condensable gas that is discharged to the top of the (meth) acrylic acid absorption tower (100) can be fed to a recovery stage of organic by-products (particularly acetic acid) , included in non-condensable gas, and the rest can be fed to a gas waste incinerator. That is, according to an embodiment of the invention, a non-condensable gas contact step that is discharged to the upper part of the (meth) acrylic acid absorption tower (100) with water absorbing solvent to recover the acetic acid included in the non-condensable gas can still be conducted.
    [057] According to the present invention, the step of contacting non-condensable gas with an absorption solvent can be conducted in an acetic acid absorption tower (150). In addition, for an effective acetic acid absorption process, the acetic acid absorption tower (150) can be operated at a pressure of 1 to 1.5 bar, and preferably from 1 to 1.3 bar, and the temperature internal of the acetic acid absorption tower (150) can be controlled from 50 to 100 ° C, and preferably from 50 to 80 ° C. In addition, the specific operating conditions of the acetic acid absorption tower (150) may follow the Korean patent open to the public number 2009-0041355 of the applicant.
    [058] Here, an absorption solvent for the specific absorption of acetic acid among the by-products included in the non-condensable gas can be fed to the upper part of the acetic acid absorption tower (150), and an aqueous solution containing acetic acid can be fed. discharged to the bottom of the acetic acid absorption tower (150).
    [059] As the acetic acid-absorbing solvent, the same type as the (meth) acrylic acid-absorbing solvent explained above, and preferably the aqueous solution containing acetic acid, which is discharged from the absorption tower can be used. acetic acid (150) can be fed to the (meth) acrylic acid absorption tower (100) and used as an absorption solvent. In addition, the gas taken from the acetic acid is discharged to the top of the acetic acid absorption tower (150) and can be recycled to the (meth) acrylic acid synthesis reaction step explained above and reused.
    [060] Meanwhile, the continuous (meth) acrylic acid recovery method includes a step of dividing and feeding the aqueous (meth) acrylic acid solution that is discharged from the (meth) acrylic acid absorption tower (100) to the (meth) acrylic acid extraction tower (200) and the water separation tower (300).
    [061] According to the present invention, as shown in figure 1, the (meth) acrylic acid absorption tower (100) is connected simultaneously to the (meth) acrylic acid extraction tower (200) and the separation tower water (300) through the transfer tubes of aqueous (meth) acrylic acid I (102 and 103), respectively, and the (meth) acrylic acid extraction tower (200) is connected to the water separation tower (300) through a 203 (meth) acrylic acid transfer tube.
    [062] The (meth) acrylic acid extraction tower (200) is an apparatus for the removal of water that has been used as an absorption solvent in the step of obtaining an aqueous solution of (meth) acrylic acid and the recovery of an extract with a higher concentration of (meth) acrylic acid in it.
    [063] In addition, the water separation tower (300) is an apparatus for azeotroping the aqueous solution of (meth) acrylic acid fed from the absorption tower of (meth) acrylic acid (100) and the extract of (meth) acrylic acid fed from the (meth) acrylic acid extraction tower (200), to recover the (meth) acrylic acid from it. The (meth) acrylic acid extraction tower (200) and the water separation tower (300) will be explained later.
    [064] As explained above, in the previously disclosed (meth) acrylic acid recovery method by means of azeotropic distillation, the aqueous solution of all (meth) acrylic acid obtained from the (meth) acrylic acid absorption tower ( 100) is fed to a water separation tower (300) and distilled.
    [065] On the contrary, the method of continuous (meth) acrylic acid recovery according to the present invention introduces a (meth) acrylic acid extraction tower (200) before the water separation tower (300), thereby reducing largely the treatment charge of the aqueous (meth) acrylic acid solution in the water separation tower (300) and the amount of energy consumption.
    [066] Furthermore, the method of the present invention divides and supplies the aqueous solution of (meth) acrylic acid obtained from the (meth) acrylic acid absorption tower (100) to the (meth) acrylic acid extraction tower (200) and the water separation tower (300), thus reducing the overall load of the installation, while minimizing a polymerization reaction of (met) acrylic acid in the water separation tower (300), thus providing better operational stability.
    [067] According to the present invention, the ratio of division and feeding of the (meth) acrylic acid obtained from the (meth) acrylic acid absorption tower (100) to the (meth) acrylic acid extraction tower ( 200) and the water separation tower (300) can be determined by considering a proportion of the capacity of the (met) acrylic acid extraction tower (200) and the water separation tower (300), the treatment capacity , effect of improving the energy efficiency of the global process and the like.
    [068] Taking the above conditions into account, it is advantageous that 5 ~ 70% by weight, more preferably 20 ~ 50% by weight of the aqueous solution of (meth) acrylic acid obtained from the acid absorption tower ( met) acrylic (100) are fed to the extraction tower of the (met) acrylic acid (200), and the rest can be fed to the water separation tower (300).
    [069] In other words, the ratio of the content (% by weight) of the aqueous (meth) acrylic acid solution divided and fed from the (meth) acrylic acid absorption tower (100) to the acid extraction tower (met) acrylic (200) and the water separation tower (300) can be 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40: 60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, or the like, preferably 20:80 to 70:30, more preferably 30:70 to 60:40 and more preferably from 40:60 to 50:50. However, the present invention is not limited to the reasons exemplified above, and that ratio can be varied variably within the above range, considering the purpose and effect of the present invention.
    [070] According to the present invention, as the amount of aqueous (meth) acrylic acid solution fed to the (meth) acrylic acid extraction tower (200) becomes greater, the effect of splitting the treatment with the tower water separation (300) can be improved and thus the energy efficiency of the total process can be improved.
    [071] However, if the excess aqueous solution of (meth) acrylic acid is fed to the extraction tower (200), an extraction tower (200) that has greater capacity may be required, the operating conditions of the water separation (300) at the rear end may become inferior, thus increasing the loss of (meth) acrylic acid to reduce the efficiency of the process and thus it is advantageous that the feed ratio of the aqueous acid solution (met) ) acrylic is controlled within the range explained above.
    [072] In addition, as the amount of aqueous (meth) acrylic acid fed to the water separation tower (300) becomes greater, the amount of water that should be removed by azeotropic distillation in the water separation tower (300) can be increased, thus decreasing the effect of reducing energy consumption, in such a way that it is advantageous for the proportion of feed of the aqueous solution of (meth) acrylic acid to be controlled within the range explained above.
    [073] The aqueous (meth) acrylic acid solution can be split and fed from the (meth) acrylic acid absorption tower (100) through the aqueous (meth) acrylic acid transfer tubes (102 and 103), respectively, connected to the (met) acrylic acid extraction tower (200) and the water separation tower (300). The aqueous solution of (meth) acrylic acid can be divided and fed at the ratio previously explained by means of common installed in the transfer pipes (102 and 103).
    [074] Meanwhile, the method of continuous recovery of (meth) acrylic acid according to the present invention includes a step of obtaining a (meth) acrylic acid extract with a reduced water content from the aqueous acid solution (met) acrylic that is fed to the (met) acrylic acid extraction tower (200) and fed to the water separation tower (300) (hereinafter referred to as an "extraction process").
    [075] According to the present invention, the (meth) acrylic acid extraction tower (200) receives a part of the aqueous (meth) acrylic acid solution obtained from the (met) acrylic acid absorption tower (100) ), removes most of the water included in the aqueous (meth) acrylic acid solution without using a significant amount of energy, and feeds it to the water separation tower (300), thereby reducing the energy used for azeotropic distillation of the water separation tower (300), as described below.
    [076] At present, the (meth) acrylic acid extract can be obtained by contacting the aqueous (meth) acrylic acid solution that is fed to the (meth) acrylic acid extraction tower (200) with a hydrophobic extraction solvent to remove the water included in the aqueous solution. That is, it is preferable in terms of improving the energy efficiency of the overall process for the extraction in the (meth) acrylic acid extraction tower (200) in order to use a liquid-liquid contact method.
    [077] The hydrophobic extraction solvent can be a hydrocarbon solvent that forms an azeotrope with water and organic by-products (acetic acid and the like), and that does not form an azeotrope with (meth) acrylic acid, but can extract the same from enough way. In addition, it can have a boiling point of 10 to 120 ° C, in order to improve the efficiency of the extraction process.
    [078] According to the present invention, the hydrophobic extraction solvent satisfying the properties described above can be at least one solvent selected from the group consisting of benzene, toluene, xylene, n-heptane, cycloheptane, cycloheptene, 1-heptene, ethyl-benzene, methyl-cyclohexane, n-butyl acetate, isobutyl acetate, isobutyl acrylate, n-propyl acetate, isopropyl acetate, methyl isobutyl ketone, 2- methyl-1-heptene, 6-methyl-1-heptene, 4-methyl-1-heptene, 2-ethyl-1-hexene, ethylcyclopentane, 2-methyl-1-hexene, 2,3-dimethylpentane, 5-methyl- 1-hexene and isopropyl-butyl ether.
    [079] However, it is advantageous in terms of improving process efficiency that the temperature of the aqueous (meth) acrylic acid is 10 to 70 ° C in the extraction process, and that the weight ratio of the hydrophobic extraction solvent for the aqueous solution of (meth) acrylic acid it is 1: 1 to 1: 5, preferably 1: 1.2 to 1: 2.5.
    [080] In addition, in the extraction process, a common extraction device can be used according to a liquid-liquid contact method. Non-limiting examples of the extraction apparatus may include a Karr shuttle plate column, a rotary disk contactor, a Scheibel column, a Kuhni column, a spray extraction tower, a packed extraction tower, a pulsed packed column, a mixer-decanter, a centrifugal counter-current extractor, and the like.
    [081] By this method, extract of (meth) acrylic acid from which most of the water included in the aqueous solution of (meth) acrylic acid can be obtained, and preferably, extract of (meth) acid acrylic is discharged to the top of the (meth) acrylic acid extraction tower (200), and the discharged extract is fed to the water separation tower (300) through the (meth) acrylic acid transfer tubing ( 203).
    [082] In addition, at least a portion of the lower liquid discharged from the (meth) acrylic acid extraction tower (200) can be fed to the upper end of the (meth) acrylic acid absorption tower (100) and used as a part of the (meth) acrylic acid-absorbing solvent, and a part of the bottom liquid discharged can be treated as waste water.
    [083] It is also preferable in terms of improving the efficiency of the absorption process than the upper end of the (meth) acrylic acid absorption tower (100) in which the lower liquid discharged from the extraction tower (200) is recycled either by minus one point corresponding to the height of 70% or more of the lowest part of the absorption tower (100). In addition, it is preferable that (meth) acrylic acid is not included in the lower liquid discharged from the (meth) acrylic acid extraction tower (200), but it can be included a little, and the amount can be preferably 5% in weight or less.
    [084] Meanwhile, the method of continuous recovery of (meth) acrylic acid according to the present invention includes a step of distillation of the aqueous solution of (meth) acrylic acid and (meth) acrylic acid extract which are fed to the tower of water separation (300) to obtain (meth) acrylic acid (hereinafter referred to as a "distillation process").
    [085] The distillation process is a process for azeotropically distilling the aqueous (meth) acrylic acid solution that is fed from the (meth) acrylic acid absorption tower (100) to the water separation tower (300) and the (meth) acrylic acid extract that is fed from the (meth) acrylic acid extraction tower (200) to the water separation tower (300), thereby removing water and organic by-products and separating and obtaining the acid (met) acrylic.
    [086] The aqueous solution of (meth) acrylic acid and the extract of (meth) acrylic acid are fed to the water separation tower (300), respectively, through the separate transfer lines (103 and 203), in which the location of the water separation tower (300) to which each solution is fed can be the same or different, but it is advantageous in terms of improving the efficiency of the process for the solutions to be fed to the same location.
    [087] However, according to the present invention, it is advantageous that the distillation in the water separation tower (300) is carried out in the presence of a hydrophobic, azeotropic solvent, because it can simultaneously recover the water and organic by-products (acetic acid and the like).
    [088] The hydrophobic, azeotropic solvent is a hydrophobic solvent that can form an azeotropic mixture with water and acetic acid, and that does not form an azeotrope with (meth) acrylic acid, and hydrocarbon solvents that satisfy the properties described above can be used without specific limitations. In addition, the hydrophobic, azeotropic solvent may have a lower boiling point than (meth) acrylic acid and, preferably, it may have a boiling point of 10 to 120 ° C.
    [089] Hydrophobic, azeotropic solvents that satisfy the properties described above may include at least one selected from the group consisting of benzene, toluene, xylene, n-heptane, cycloheptane, cycloheptene, 1-heptene, ethylbenzene , methyl-cyclohexane, n-butyl acetate, isobutyl acetate, isobutyl acrylate, n-propyl, isopropyl acetate, methyl isobutyl ketone, 2-methyl-1-heptene, 6-methyl-1-heptene , 4-methyl-1-heptene, 2-ethyl-1-hexene, ethylcyclopentane, 2-methyl-1-hexene, 2,3-dimethylpentane, 5-methyl-1-hexene, and isopropyl-butyl ether.
    [090] The hydrophobic, azeotropic solvent can be identical or different from the hydrophobic extraction solvent that is applied to the (meth) acrylic acid extraction tower (200). However, considering the production efficiency according to the continuous process, the hydrophobic, azeotropic solvent preferably includes the same compounds as the hydrophobic extraction solvent.
    [091] As such, if the same compound is used as an azeotropic solvent and the extraction solvent, at least part of the azeotropic solvent that is distilled in the water separation tower (300) and recovered can be fed to the bottom of the extraction tower for (meth) acrylic acid (200) and used as a part of the extraction solvent.
    [092] Meanwhile, the water separation tower (300) can be equipped with a packed column or a multi-stage column, including the load explained above, preferably a sieve tray column or a flow tray column double, inside.
    [093] If the hydrophobic, azeotropic solvent is introduced at the top of the water separation tower (300), the (meth) acrylic acid azeotrope and the absorption solvent (for example, water) may be disrupted. Thus, water and acetic acid in the aqueous (meth) acrylic acid solution fed directly from the (meth) acrylic acid absorption tower (100); a part of water, acetic acid, and hydrophobic extraction solvent, which are not removed from the (met) acrylic acid extraction tower (200); and the hydrophobic, azeotropic solvent used for azeotropic distillation can form an azeotrope and be recovered from the top of the water separation tower (300). In addition, discharged liquid containing (meth) acrylic acid can be recovered from the bottom of the water separation tower (300).
    [094] The upper liquid discharged from the water separation tower (300) can be fed to a phase separator (350) and subjected to a predetermined treatment and then reused. The phase separator (350) is a device for separating phases from liquids that are not mixed with each other using gravity or centrifugal force and the like, and a relatively light liquid can be recovered from the top of the phase separator (350), while a relatively high liquid can be recovered from the bottom of the phase separator (350).
    [095] In the present invention, for example, in the case of using water as a (meth) acrylic acid absorption solvent, the discharged upper liquid which is fed to the phase separator (350) can be separated into an organic phase containing a hydrophobic, azeotropic solvent and an aqueous phase containing water.
    [096] At least part of the organic layer that separates in the phase separator (350) can be fed to the upper end of the water separation tower (300) and used as an azeotropic solvent, and the rest of the organic phase can be fed to the (meth) acrylic acid extraction tower (200) and used as an extraction solvent, if necessary. At least a part of the aqueous layer separating in the phase separator (350) can be fed to the upper end of the (meth) acrylic acid absorption tower (100) and used as an absorption solvent, and a part thereof, can be treated as wastewater.
    [097] Acetic acid can be included in the water layer, and the concentration of acetic acid included in the aqueous phase can be varied according to the type of azeotropic solvents and reflux ratio of the column installed in the water separation tower and the like. According to the present invention, the concentration of acetic acid included in the aqueous layer of the upper discharged liquid can be from 1 to 50% by weight, preferably 2 to 40% by weight, more preferably 3 to 30% by weight.
    [098] Meanwhile, discharged liquid containing (meth) acrylic acid is recovered from the bottom of the water separation tower (300), which is crude (meth) acetic acid and can be fed to an additional purification process as needed.
    [099] Water, acetic acid and the azeotropic solvent can be included in the lower liquid discharged from the water separation tower (300), and preferably, water, acetic acid, and the azeotropic solvent can be included in an amount, respectively less than 0.1% by weight, so that the lower liquid discharged can be used as crude (meth) acrylic acid.
    [0100] While the aqueous solution of (meth) acrylic acid passes through the (meth) acrylic acid absorption tower (100), the (meth) acrylic acid extraction tower (200), the water separation tower ( 300), and the like, at least a portion of (meth) acrylic acid included in the aqueous solution can be polymerized to produce a polymer, such as a dimer or oligomer and the like. In order to minimize the polymerization of (meth) acrylic acid, a polymerization inhibitor can be added to the water separation tower (300), and commonly used polymerization inhibitors can be employed without specific limitations.
    [0101] Meanwhile, in the lower liquid discharged from the water separation tower (300), high-boiling by-products, such as a (meth) acrylic polymer, a polymerization inhibitor, and the like can be included in addition to (meth) acrylic acid. Thus, as necessary, a step of feeding the lower liquid discharged from the water separation tower (300) to a high boiling point by-product separation tower (400) to separate the high boiling by-products included in the liquid unloaded bottom can still be driven.
    [0102] The high boiling point by-product separation tower (400) can have a common structure, which can be operated under common reaction conditions, and the reaction and construction conditions of the separation tower are not specifically limited. High boiling point by-products included in the lower liquid discharged from the water separation tower (300) can be recovered from the bottom of the high boiling point by-product separation tower (400), and crude (meth) acrylic acid (CAA) ) free of high boiling point by-products can be recovered from the upper part of the high boiling point by-product separation tower (400).
    [0103] Crude (meth) acrylic acid (CAA) can be obtained in the form of high purity (meth) acrylic acid (HPAA), through an additional crystallization process.
    [0104] Each step that can be included in the (meth) acrylic acid recovery method according to the present invention can be carried out continuously, and in addition to the steps explained above, all steps generally performed in the field of the technique to which belongs to the invention can be carried out before or after each stage.
    [0105] For example, a process of feeding the aqueous (meth) acrylic acid solution obtained in the (meth) acrylic acid absorption tower (100) to a separate extraction tower, prior to dividing and feeding to the extraction tower (meth) acrylic acid (200) and the water separation tower (300), in order to remove low-boiling by-products (acrolein, propionaldehyde, acetaldehyde, formaldehyde, isopropyl acetate and the like) dissolved in aqueous solution (meth) acrylic acid can also be made.
    [0106] However, according to another embodiment of the invention, an apparatus for continuous recovery of (meth) acrylic acid is provided, including: an (meth) acrylic acid absorption tower (100) for contacting mixed gas including organic by-products, steam, and (meth) acrylic acid, which is produced by a reaction of synthesis of (meth) acrylic acid, with water, to obtain an aqueous solution of (meth) acrylic acid; transfer tubes of aqueous (meth) acrylic acid solution (102 and 103) that are connected from the (meth) acrylic acid absorption tower (100) to the (meth) acrylic acid extraction tower (200) and the water separation tower (300), respectively, so that the aqueous solution of (meth) acrylic acid is divided and fed; a (meth) acrylic acid extraction tower (200) for obtaining (meth) acrylic acid extract with a reduced water content from the aqueous (meth) acrylic acid solution which is fed through the transfer tubes aqueous solution of (meth) acrylic acid (102), and feeding it to a water separation tower (300); a (meth) acrylic acid transfer piping (203) that is connected from the (meth) acrylic acid extraction tower (200) to the water separation tower (300), to which the acid extract ( met) acrylic is fed; and water separation tower (300) to distill the aqueous solution of (met) acrylic acid fed through the transfer tubing of aqueous solution of (met) acrylic acid (103) and the extract of (met) acrylic acid fed through the transfer pipes of (meth) acrylic acid extract (203) to obtain (meth) acrylic acid.
    [0107] Specifically, in the apparatus according to the present invention, the (meth) acrylic acid absorption tower (100) is connected simultaneously to the (meth) acrylic acid extraction tower (200) and the water separation tower (300) through each of the transfer piping of the (met) acrylic acid solution (102 and 103), and the (met) acrylic acid extraction tower (200) that is connected to the water separation tower (300) through a transfer tube of (meth) acrylic acid extract (203).
    [0108] According to the present invention, the (meth) acrylic acid absorption tower (100) can be in the form of a packed column or a multistage column, including charges, such as Raschig rings, rings of Pali, a saddle, a gauze, a packaging structure, and the like, in order to improve the contact efficiency of the mixed gas containing (meth) acrylic acid (1) with water as the water absorption solvent.
    [0109] A common extractor according to a liquid-liquid contact method can be used as the extraction tower for (meth) acrylic acid (200) and non-limiting examples of them may include a Karr shuttle plate column, a rotating disk contact, a Scheibel column, a Kuhni column, a spray extraction tower, a packed extraction tower, a pulsed packed column, a mixer-decanter, a centrifugal countercurrent extractor, and the like.
    [0110] The water separation tower (300) can be equipped with a packed column or a multi-stage column, including the loads explained above, preferably a column of sieve trays or a column of double flow trays in the its interior.
    [0111] In addition, the acetic acid absorption tower (150), the transfer tubes of the aqueous acid solution (met) (102 and 103), the transfer tube of (met) acrylic acid extract (203) , the phase separator (350), the high-boiling by-product separation tower (400), and the like, which are shown in figure 1, may have common constructions in the field of the technique to which the invention belongs, and the action and effect in each process are as explained above.
    [0112] Hereinafter, preferred examples are presented to assist in understanding the invention. However, these examples are only to illustrate the invention and the invention is not limited to them. Example 1
    [0113] In order to verify the effects of reducing energy and improving the operational stability of the water separation tower (300) resulting from the division and the I i ntation of the aqueous acid solution (me of acid (me t ) acr Í I i co (100) for the tower (water separation tower (300), an ap showing the construction as the next stradona was driven continuously. I. Aqueous acid (meth) acrylic absorption tower of acrylic acid
    [0114] The reaction gas obtained by the oxide absorption tower of acrylic (mett) acid (acrylic acid (composition: about 68% by weight of acetic acid, and about 30% and absorption tower of acrylic acid met (1 absorption of (meth) acrylic acid.
    [0115] The aqueous solution of acrylic acid (meth) acrylic acid extraction tower ((300) in the weight ratio of 35:65. II. Aqueous (meth) acetic acid extraction tower for acrylic acid
    [0116] A reciprocating liquid-li extractor for (meth) acrylic acid (200), with 56 stages. Thirty-five percent acrylic discharged to the bottom (me t) acrylic was introduced through the end of the extraction tower (200), to a part of the reflux stream containing liquid toluene discharged from the top of the tower below it was used as an extraction solvent, through stage 56, the lowest stage of the extraction tower (200), at a flow rate of around 118.73 g / min.
    [0117] After the stable operation, an extract of acrylic acid (composition: about 64.8% by weight of toluene, about 32.9% by weight of acrylic acid, about 1 , 6% by weight of water, and about 0.6% by weight of acetic acid) was obtained from the top of the extraction tower (200), and water (composition: about 95.1% by weight of water, about 1.8% by weight of acrylic acid, and about 3.1% by weight of acetic acid) was discharged to the bottom of the extraction tower (200). As a result of the operation of the (meth) acrylic acid extraction tower (200), the rate of water removal from the aqueous acrylic acid solution fed from the (meth) acrylic acid absorption tower (100) was measured to be about 89.7%, and the removal rate of acetic acid was measured to be about 65.6%. In addition, the acrylic acid extract discharged to the top of the extraction tower (200) was fed to the water separation tower (300). III. Water separation tower - azeotropic distillation
    [0118] A double flow tray pilot column having an inner diameter of 30 mm and a total of 28 stages was employed as the water separation tower (300) and the operating pressure was maintained at 14.665 kPa (110 torr) .
    [0119] The water separation tower (300) received 65% by weight of the aqueous acrylic acid solution that is discharged to the bottom of the (meth) acrylic acid absorption tower (100) and the acid extract acrylic that is discharged to the top of the (meth) acrylic acid extraction tower (200). At this point, the aqueous acrylic acid solution was introduced in stage 14 of the upper part of the water separation tower (300) at a flow rate of about 6.08 g / min., And the acrylic acid extract was introduced in the stage 14 from the top of the water separation tower (300) at a flow rate of approximately 6.55 g / min. A part of the reflux flow of toluene that is separated from a phase separator (350) was introduced in the first stage, the extreme upper phase of the water separation tower (300), at a flow rate of about 7.66 g / min. as an azeotropic solvent.
    [0120] The heat was fed through a reflector in the lower stage of the water separation tower (300), so that the temperature of stage 16 of the water separation tower (300) became about 86 ° C or more , and the temperature of stage 12 cannot exceed about 58 ° C. After the stable operation was conducted for about 10 hours at a steady state, a distillate was discharged to the top of the water separation tower (300) at a flow rate of 14.01 g / min., And a flow of acrylic acid of 6.29 g / min. was obtained from the bottom of the water separation tower (300). Here, in a stable state, the temperature of the upper part of the water separation tower (300) was maintained at about 40.1 ° C, and the temperature of the lower part was maintained at about 96.9 ° C.
    [0121] As a result of the water separation operation of the tower (300), the removal rate of water and acetic acid included in the acrylic acid extract and the aqueous solution of acrylic acid fed to the water separation tower was about 99% or more, acrylic acid flow in which most of the water and acetic acid were removed, which could be obtained from the bottom of the water separation tower (300), and acrylic acid that was lost to the upper part of the water separation tower (300) was about 0.22% by weight.
    [0122] The water separation tower (300) can be operated in a stable manner, without the production of a polymer in the tower, even after 10 days of long-term operation.
    [0123] Table 1 below shows the flow and concentration of each flow to a stationary stage operation of the water separation tower (300). Table 1

    [0124] The quantity for treatment of the aqueous acrylic acid solution through the (met) acrylic acid absorption tower (100), the (met) acrylic acid extraction tower (200), and a water separation tower (300 ) was about 9.4 g per minute, the amount of acrylic acid production was about 6.3 g per minute, and the total recovery rate of acrylic acid was about 99.6%. As a result of the energy consumption calculation, using an Aspen Plus process simulator program (AspenTech Inc.), it was confirmed that 22.7 cal were consumed per 1 g of the obtained acrylic acid. Example 2
    [0125] An aqueous solution of acrylic acid was obtained from the (meth) acrylic acid absorption tower (100) by the same method as in Example 1.
    [0126] The aqueous solution of acrylic acid obtained was fed to the extraction tower of the (meth) acrylic acid (200) and the water separation tower (300) in an amount of 50% by weight each. Here, the aqueous acrylic acid solution discharged from the (met) acrylic acid absorption tower (100) and the acrylic acid extract discharged from the (met) acrylic acid extraction tower (200) were introduced in the stage 14 from the top of the water separation tower (300), respectively, with a flow rate of about 5.75 g / min and about 11.5 g / min.
    [0127] The reflux of toluene from the top of the water separation tower (300) was introduced in the first stage, which is the highest stage at a flow rate of 4.4 g / min. The heat was fed through a reflector at the bottom of the water separation tower (300), so that the temperature of stage 16 became about 81 ° C or more, and the temperature of the 12th stage cannot be greater than about 49 ° C.
    [0128] After the stable operation was conducted for about 10 hours, in a steady state, the distillate was discharged to the top of the water separation tower (300) at a flow rate of about 14.0 g / min., and an acrylic acid flow of about 7.65 g / min., was obtained from the bottom of the water separation tower (300). Here, in a stable state, the temperature of the upper part of the water separation tower (300) was maintained at about 40.4 ° C, and the temperature of the lower part was maintained at about 96.2 ° C.
    [0129] As a result of the water separation operation of the tower (300), the removal rate of water and acetic acid included in the acrylic acid extract and the aqueous solution of acrylic acid fed to the water separation tower was about 98% or more, the flow of acrylic acid in which most of the water and acetic acid were removed could be obtained from the bottom of the water separation tower and lost acrylic acid to the top of the water separation tower was about 0.50% by weight.
    [0130] The water separation tower (300) can be operated in a stable manner, without the production of a polymer in the tower, even after 10 days of long-term operation. Table 2 below shows the flow and concentration of each flow in a stationary stage operation of the water separation tower (300). Table 2

    [0131] The quantity for treatment of the aqueous acrylic acid solution through the (met) acrylic acid absorption tower (100), the (met) acrylic acid extraction tower (200), and a water separation tower (300 ) was about 11.5 g per minute, the amount of acrylic acid production was about 7.65 g per minute and the total recovery rate of acrylic acid was about 99.1%. As a result of the energy consumption calculation, using an Aspen Plus process simulator program (AspenTech Inc.), it was confirmed that 18.7 cal were consumed per 1 g of the obtained acrylic acid. Comparative Example 1: azeotropic distillation by feeding the total amount of an aqueous solution of acrylic acid to a water separation tower
    [0132] An aqueous solution of acrylic acid was obtained from the (meth) acrylic acid absorption tower (100) by the same method as in Example 1.
    [0133] The total amount of the aqueous acrylic acid solution obtained was fed to the water separation tower (300). Here, the aqueous solution of acrylic acid discharged from the (meth) acrylic acid absorption tower (100) was introduced in stage 14 of the upper part of the water separation tower (300) at a flow rate of about 6.5 g / min.
    [0134] The reflux of toluene from the upper part of the water separation tower (300) was introduced in the first stage, ie the upper extreme stage at a flow rate of 11.95 g / min. The heat was fed through a reflector at the bottom of the water separation tower (300), so that the temperature of the 16th stage became about 88 ° C or more, and the temperature of the 12th stage cannot be greater than about 65 ° C.
    [0135] After the stable operation was conducted for about 10 hours, in a steady state, distillate was discharged to the top of the water separation tower (300) at a flow rate of about 14.14 g / min ., and acrylic acid flow of about 4.31 g / min. was obtained from the bottom of the water separation tower (300). Here, in a stable state, the temperature of the upper part of the water separation tower (300) was maintained at about 40.4 ° C, and the temperature of the lower part was maintained at about 97.1 ° C.
    [0136] As a result of the operation of the water separation tower (300), the removal rate of water and acetic acid included in the acrylic acid extract and the aqueous solution of acrylic acid fed to the water separation tower was about of 99% or more, the flow of acrylic acid in which most of the water and acetic acid were removed could be obtained from the bottom of the water separation tower and lost acrylic acid to the top of the water separation tower was of about 0.13% by weight.
    [0137] When the water separation tower (300) was operated for 5 days, polymer production was observed in the stages around the feeding stage in the tower, and then operated for 10 days, normal operation could not be performed longer due to the production of polymer in the tower.
    [0138] Table 3 below shows the flow and concentration of each flow in a stationary stage operation of the water separation tower (300). Table 3

    [0139] The amount for treating the aqueous solution of acrylic acid through the (meth) acrylic acid absorption tower (100) and a water separation tower (300) was about 6.5 g per minute, the amount acrylic acid production was about 4.31 g per minute, and the total recovery rate for acrylic acid was about 99.8%. As a result of the energy consumption calculation, using an Aspen Plus process simulator program (AspenTech Inc.), it was confirmed that 30.32 cal were consumed per 1 g of the obtained acrylic acid. Comparative Example 2: Sequential passage through [acrylic acid absorption tower - extraction tower - water separation tower]
    [0140] An aqueous solution of acrylic acid was obtained from the (meth) acrylic acid absorption tower (100) by the same method as in Example 1. The total amount of the aqueous acrylic acid solution obtained was fed to the extraction tower. (meth) acrylic acid (200), and the acrylic acid extract discharged from the (meth) acrylic acid extraction tower (200) was fed to the water separation tower (300).
    [0141] Thus, the water separation tower (300) was fed only with the acrylic acid extract, and the acrylic acid extract was introduced in the 14th stage at the top of the water separation tower (300) at a flow rate of about 8.3 g / min.
    [0142] The reflux of toluene from the top of the water separation tower (300) was introduced in the first stage, which is the highest stage at a flow rate of about 8.4 g / min as a solvent. This corresponds to a reflux rate (that is, the ratio of the flow from reflux liquid to discharged liquid) of about 1.5.
    [0143] The heat was supplied through a reflector at the bottom of the water separation tower (300), so that the temperature of the 16th stage became about 88 ° C or more, and the temperature of 12 ° stage cannot be higher than about 65 ° C.
    [0144] After the stable operation was conducted for about 10 hours, in a steady state, distillate was discharged to the top of the water separation tower (300) at a flow rate of about 14.10 g / min ., and acrylic acid flow of about 2.65 g / min. was obtained from the bottom of the water separation tower (300). Thus, in a stable state, the temperature of the upper part of the water separation tower (300) was maintained at about 41.2 ° C, and the temperature of the lower part was maintained at about 96.5 ° C.
    [0145] As a result of the operation of the water separation tower (300), the removal rate of water and acetic acid included in the acrylic acid extract and the aqueous acrylic acid solution supplied to the water separation tower was about 99% or more, the flow of acrylic acid in which most of the water and acetic acid have been removed can be obtained from the bottom of the water separation tower, and the acrylic acid lost in the upper part of the water separation tower water was about 1.07% by weight.
    [0146] The water separation tower (300) can be operated in a stable manner, without the production of a polymer in the tower even after 10 days of long-term operation.
    [0147] Table 4 below shows the flow and concentration of each flow in stationary stage operation of the water separation tower (300). Table 4

    [0148] The amount to treat the aqueous solution of acrylic acid through this process was about 4.15 g per minute, the amount of acrylic acid production was about 2.65 g per minute, and the recovery rate total acrylic acid was about 94.8%. As a result of the energy consumption calculation, using an Aspen Plus process simulator program (AspenTech Inc.), it was confirmed that 54.25 cal were consumed per 1 g of the obtained acrylic acid. Discussion
    [0149] As can be seen from the operating results of Examples 1 ~ 2 and Comparative Examples 1 ~ 2, according to the method of Example 1, there was a reduction of 7.6 cal per 1 g of acrylic acid recovered compared to the method of Comparative Example 1, which corresponds to an energy reduction of about 25.1%. In addition, according to the method of Example 2, there was a decrease of about 11.62 cal per 1 g of the recovered acrylic acid compared to Comparative Example 1, which corresponds to an energy reduction of about 38, 3%.
    [0150] According to the method of Example 1, there was a decrease of about 31.52 cal per 1 g of the recovered acrylic acid compared to Comparative Example 2, which corresponds to an energy reduction of 58, 1%. In addition, according to the method of Example 2, there was a decrease of about 35.54 cal per 1 g of the recovered acrylic acid compared to Comparative Example 2, which corresponds to an energy reduction of about 65, 5%.
    [0151] As such, it is confirmed that the continuous (meth) acrylic acid recovery method according to the present invention can maintain a (meth) acrylic acid recovery rate equivalent to the previous recovery method, using a single tower water separation (the method of the comparative example), and it can still largely reduce energy consumption.
    [0152] In addition, if a distillation apparatus with an equivalent capacity is used and equivalent amounts of azeotropic solvents and operating energy are introduced, the method according to the present invention can further increase the treatment capacity of an aqueous solution of (meth) acrylic acid, and recover (meth) acrylic acid, with high energy efficiency. In addition, the method according to the present invention can maintain a low temperature, around a feeding stage of a water separation tower that has a relatively high possibility of producing a (meth) acrylic acid polymer, and, thus, it is effective in preventing the production of a polymer, thus providing a further improvement in operational stability. Description of reference numbers and signs 1: (met) acrylic acid containing mixed gas 100: (met) acrylic acid absorption tower 102, 103: transfer tubes of aqueous (met) acrylic acid 150: absorption tower acetic acid 200: acrylic (met) acid extraction tower 203: acrylic (met) acid extract transfer piping 300: water separation tower 350: phase separator 400: high boiling by-product separation tower
    权利要求:
    Claims (18)
    [0001]
    1. Method of continuous recovery of (meth) acrylic acid, CHARACTERIZED by the fact that it comprises: contact of a gas mixture comprising (meth) acrylic acid, organic by-products and steam, which is produced by an acid (meth) synthesis reaction acrylic with water in a (meth) acrylic acid absorption tower (100) to obtain an aqueous solution of (meth) acrylic acid; dividing and feeding the aqueous (meth) acrylic acid solution to a (meth) acrylic acid extraction tower (200) and a water separation tower (300); obtaining a (met) acrylic acid extract with a reduced water content from the aqueous (met) acrylic acid solution that is fed to the (met) acrylic acid extraction tower (200), and feeding it to a water separation tower (300); and distilling the aqueous (meth) acrylic acid solution and (meth) acrylic acid extract which are fed to the water separation tower (300) to obtain (meth) acrylic acid.
    [0002]
    2. Method for continuous recovery of (meth) acrylic acid, according to claim 1, CHARACTERIZED by the fact that 5 ~ 70% by weight of the aqueous solution of (meth) acrylic acid obtained in the acid (meth) absorption tower acrylic (100) is fed to the (meth) acrylic acid extraction tower (200), and the rest is fed to the water separation tower (300).
    [0003]
    3. Method for continuous recovery of (meth) acrylic acid according to claim 1, CHARACTERIZED by the fact that the (meth) acrylic acid synthesis reaction is an oxidation reaction of at least one compound selected from the group which consists of propane, propylene, butane, isobutylene, f-butylene, and (meth) acrolein in the presence of a gas phase catalyst.
    [0004]
    4. Method for continuous recovery of (meth) acrylic acid, according to claim 1, CHARACTERIZED by the fact that the internal temperature of the (meth) acrylic acid absorption tower (100) is maintained at 50 to 100 ° C.
    [0005]
    5. Method for continuous recovery of (meth) acrylic acid, according to claim 1, CHARACTERIZED by the fact that in the step of obtaining the aqueous solution of (meth) acrylic acid, an aqueous solution of (meth) acrylic acid is discharged to the bottom of the (met) acrylic acid absorption tower (100), and non-condensable gas devoid of (met) acrylic acid is discharged to the top of the (met) acrylic acid absorption tower (100).
    [0006]
    6. Method for continuous recovery of (meth) acrylic acid, according to claim 5, CHARACTERIZED by the fact that it additionally comprises contact of the non-condensable gas with water to recover the acetic acid that is included in the non-condensable gas.
    [0007]
    7. Method for continuous recovery of (meth) acrylic acid according to claim 1, CHARACTERIZED by the fact that the water fed to the (meth) acrylic acid absorption tower (100) includes organic by-products at a concentration of 3 to 20% by weight.
    [0008]
    8. Method for continuous recovery of (meth) acrylic acid, according to claim 1, CHARACTERIZED by the fact that the aqueous solution of (meth) acrylic acid obtained in the (meth) acrylic acid absorption tower (100) includes acid (met) acrylic at a concentration of 40 to 90% by weight.
    [0009]
    9. Method for continuous recovery of (meth) acrylic acid, according to claim 1, CHARACTERIZED by the fact that the (meth) acrylic acid extract is obtained by contacting the aqueous solution of (meth) acrylic acid that is fed to the (meth) acrylic acid extraction tower (200) with a hydrophobic extraction solvent to remove the water included in the aqueous solution.
    [0010]
    10. Method for continuous recovery of (meth) acrylic acid according to claim 9, CHARACTERIZED by the fact that the hydrophobic extraction solvent is at least one selected from a group consisting of benzene, toluene, xylene, n-heptane, cycloheptane, cycloheptene, 1-heptene, ethyl-benzene, methyl-cyclohexane, n-butyl acetate, isobutyl acetate, isobutyl acrylate, n-propyl acetate, isopropyl acetate, methyl-isobutyl- ketone, 2-methyl-1-heptene, 6-methyl-1-heptene, 4-methyl-1-heptene, 2-ethyl-1-hexene, ethylcyclopentane, 2-methyl-1-hexene, 2,3-dimethylpentane, 5-methyl-1-hexene and isopropyl-butyl ether.
    [0011]
    11. Method for continuous recovery of (meth) acrylic acid according to claim 9, CHARACTERIZED by the fact that the (meth) acrylic acid extract is obtained from the top of the (meth) acrylic acid extraction tower (200 ) and fed to the water separation tower (300), and at least part of the lower liquid discharged from the (met) acrylic acid extraction tower (200) is fed to the upper end of the (met) acrylic acid absorption tower (100) and used as an acid (meth) acrylic acid absorption solvent.
    [0012]
    12. Method for continuous recovery of (meth) acrylic acid according to claim 11, CHARACTERIZED by the fact that the lower liquid discharged from the (meth) acrylic acid extraction tower (200) includes (meth) acrylic acid at a concentration of 5% by weight or less.
    [0013]
    13. Method for continuous recovery of (meth) acrylic acid, according to claim 11, CHARACTERIZED by the fact that the upper end of the (meth) acrylic acid absorption tower (100), in which at least part of the liquid bottom discharged from the (meth) acrylic acid extraction tower (200) is fed is at least one point that corresponds to a height of 70% or more of the lower part of the absorption tower.
    [0014]
    14. Continuous method for recovery of (meth) acrylic acid, according to claim 1, CHARACTERIZED by the fact that the distillation in the water separation tower (300) is conducted in the presence of a hydrophobic, azeotropic solvent.
    [0015]
    15. Method for the continuous recovery of (meth) acrylic acid according to claim 14, CHARACTERIZED by the fact that the hydrophobic, azeotropic solvent is at least one selected from a group consisting of benzene, toluene, xylene, n-heptane, cycloheptane, cycloheptene, 1-heptene, ethyl-benzene, methyl-cyclohexane, n-butyl acetate, isobutyl acetate, isobutyl acrylate, n-propyl acetate, isopropyl acetate, methyl-isobutyl- ketone, 2-methyl-1-heptene, 6-methyl-1-heptene, 4-methyl-1-heptene, 2-ethyl-1-hexene, ethylcyclopentane, 2-methyl-1-hexene, 2,3-dimethylpentane, 5-methyl-1-hexene, and isopropyl-butyl ether.
    [0016]
    16. Method for continuous recovery of (meth) acrylic acid, according to claim 15, CHARACTERIZED by the fact that the hydrophobic, azeotropic solvent includes the same compound as the hydrophobic extraction solvent in the (meth) acrylic acid extraction tower (200).
    [0017]
    17. Method for continuous recovery of (meth) acrylic acid according to claim 14, CHARACTERIZED by the fact that the discharged liquid including (meth) acrylic acid is recovered from the bottom of the water separation tower (300), and the discharged liquid including a hydrophobic, azeotropic solvent, water and acetic acid is recovered from the upper part of the water separation tower (300), by means of distillation in the water separation tower (300).
    [0018]
    18. Method for continuous recovery of (meth) acrylic acid according to claim 17, CHARACTERIZED by the fact that the liquid discharged from the top of the water separation tower (300) is separated into an organic phase including the hydrophobic azeotropic solvent and an aqueous layer including acetic acid, at least a part of the organic layer being fed to the upper end of the water separation tower (300) as an azeotropic solvent, and at least a part of the aqueous layer being fed to the upper end of the absorption tower (meth) acrylic acid (100) as the absorption solvent.
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    同族专利:
    公开号 | 公开日
    CN104470884A|2015-03-25|
    IN2015DN00430A|2015-06-19|
    US20150203431A1|2015-07-23|
    KR20140018791A|2014-02-13|
    KR101546464B1|2015-08-21|
    US9517997B2|2016-12-13|
    BR112015002422A2|2017-07-04|
    CN104470884B|2017-02-22|
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    KR101616553B1|2013-08-30|2016-04-28|주식회사 엘지화학|Process for continuous recovering acrylic acid and apparatus for the process|
    KR101601938B1|2013-08-30|2016-03-09|주식회사 엘지화학|Process for continuous recovering acrylic acid and apparatus for the process|
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    KR102251790B1|2016-12-06|2021-05-12|주식회사 엘지화학|Process for continuous recovering acrylic acid|
    KR102319305B1|2016-12-06|2021-10-28|주식회사 엘지화학|Process for continuous recovering acrylic acid and apparatus for the process|
    法律状态:
    2018-12-04| B06F| Objections, documents and/or translations needed after an examination request according art. 34 industrial property law|
    2019-12-17| B06U| Preliminary requirement: requests with searches performed by other patent offices: suspension of the patent application procedure|
    2020-07-07| B09A| Decision: intention to grant|
    2020-11-10| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 09/07/2013, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    KR20120085339|2012-08-03|
    KR10-2012-0085339|2012-08-03|
    PCT/KR2013/006101|WO2014021560A1|2012-08-03|2013-07-09|Method for continuously recovering acrylate, and recovery apparatus|
    KR10-2013-0080189|2013-07-09|
    KR1020130080189A|KR101546464B1|2012-08-03|2013-07-09|Process for continuous recovering acrylic acid and apparatus for the process|
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