Purification device

Abstract

The present invention provides a method for obtaining a high-quality product. The present invention is a purification device for purifying crystals, which is configured by including: a hydraulic washing column provided with an extraction port for circulating slurry containing crystals and a return port for circulating liquid containing a melting solution of extracted crystals; a pipe for supplying slurry containing crystals to the hydraulic washing column; a filter for filtering the slurry containing crystals in the hydraulic washing column; a pipe connected to the filter for extracting a mother liquor; and a device for melting the crystals contained in the circulating slurry extracted from the extraction port, wherein the distance from the lower end of the filter to the average height of the bottom surface in the hydraulic washing column is 1000 mm or more.

Description

TECHNICAL FIELD

[0001] The present application relates to a purification device. More specifically, the present application relates to a purification device, a method for producing a compound, and a method for purifying a compound. BACKGROUND

[0002] A purification device is widely used in industry for purifying a polymerizable compound such as (meth)acrylic acid used as a raw material for a resin, and the like. A high-quality compound with further reduced impurities is required, and various superior purification devices have been studied.

[0003] In industry, crude compounds before purification of compounds are mostly purified by a continuous purification process. For example, a method for producing acrylic acid by collecting an acrylic acid-containing gas obtained by subjecting a raw material gas to a catalytic gas phase oxidation reaction, crystallization purification, and decomposing a Michael adduct of acrylic acid contained in a residual mother liquor and returning it to a collection process is disclosed (for example, see Patent Literature 1).

[0004] In the above-described purification process, as a solid-liquid separation device, a washing column such as a hydraulic washing column (HWC) is sometimes used. A purification method using a conventional washing column is disclosed in Patent Literatures 2 to 5. Note that these washing columns include a filter tube for filtering a slurry in the washing column, extracting a mother liquor, and recovering it in the inside thereof.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURES

[0007] Patent Literature 1: Japanese Patent Application Laid-Open No. 2007-182437

[0008] Patent Literature 2: Japanese Patent Application Laid-Open No. 2013-507427

[0009] Patent Literature 3: Japanese Patent Application Laid-Open No. 2012-518023

[0010] Patent Literature 4: Japanese Patent Application Laid-Open No. 2008-536893

[0011] Patent Literature 5: Japanese Patent Application Laid-Open No. 2003-530376 SUMMARY

[0012] PROBLEMS TO BE SOLVED BY THE INVENTION

[0013] As described above, a superior purification device for producing a compound is required, and a high-quality product (compound) is desired. The present application was completed in view of the above-described circumstances, and aims to provide a method for obtaining a high-quality product.

[0014] Solution to the problem

[0015] The inventors of the present application have studied purification apparatuses, focusing on a hydraulic washing column that has high washing efficiency. As a result, it was found that by making the distance from the lower end of a filter that filters a slurry containing crystals in a hydraulic washing column to the average height of the bottom surface in the hydraulic washing column 1000 mm or more, impurities, particularly acetic acid and propionic acid, which are solid solution impurities in the case where the target compound is acrylic acid, melt and re-solidify at the lower end of the filter, and thus the separation efficiency can be further improved, and a high-quality product can be obtained, thereby achieving the present application.

[0016] That is, the present application is a purification apparatus for purifying crystals, comprising: a hydraulic washing column provided with an extraction port of a circulating slurry containing crystals and a return port of a circulating liquid of a melt solution containing extracted crystals; a pipe that supplies the slurry containing crystals to the hydraulic washing column; a filter that filters the slurry containing crystals in the hydraulic washing column; a pipe connected to the filter that extracts the mother liquor; and a device that melts the crystals contained in the circulating slurry extracted from the extraction port, wherein the distance from the lower end of the filter to the average height of the bottom surface in the hydraulic washing column is 1000 mm or more.

[0017] Note that in the above Patent Documents 2 to 4, the length of the filter tube displacer disposed from the lower end of the filter to the bottom surface in the washing column is disclosed, but this length is very short, and at most 500 mm.

[0018] Effects of the invention

[0019] According to the purification apparatus of the present application, a high-quality product can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic view illustrating the use state of the purification apparatus of the present application.

[0021] Figure 2 is a schematic view illustrating the use state of the purification apparatus of the present application. DETAILED DESCRIPTION

[0022] Hereinafter, the present application will be described in detail.

[0023] Note that combining two or more of the respective preferred features of the present application described below is also a preferred mode of the present application.

[0024] Hereinafter, first, the purification apparatus of the present application will be described. Next, the compound production method of the present application, the compound purification method of the present application will be described in order.

[0025] (Purification device of the present invention)

[0026] The purification device of the present invention is configured by comprising a hydraulic washing column provided with an extraction port of circulating slurry containing crystals and a return port of circulating liquid of molten solution containing extracted crystals, a pipe that supplies the slurry containing crystals to the hydraulic washing column, a filter that filters the slurry containing crystals in the hydraulic washing column, a pipe that is connected to the filter and extracts mother liquor, and a device that dissolves the crystals contained in the circulating slurry extracted from the extraction port, and the distance from the lower end of the filter to the average height of the bottom surface in the hydraulic washing column is 1000 mm or more.

[0027] The purification device of the present invention is configured by comprising a hydraulic washing column provided with an extraction port of circulating slurry containing crystals and a return port of circulating liquid of molten solution containing extracted crystals, a pipe that supplies the slurry containing crystals to the hydraulic washing column, a filter that filters the slurry containing crystals in the hydraulic washing column, a pipe that is connected to the filter and extracts mother liquor, and a device that dissolves the crystals contained in the circulating slurry extracted from the extraction port, and the distance from the lower end of the filter to the average height of the bottom surface in the hydraulic washing column is 1000 mm or more.

[0028] The above distance is preferably 1500 mm or more, and more preferably 2000 mm or more.

[0029] In addition, in the purification device of the present invention, the distance from the lower end of the filter to the average height of the bottom surface in the hydraulic washing column is not particularly limited as long as it is 1000 mm or more, but it is preferably 10000 mm or less in consideration of the scale and efficiency of the device. It is more preferably 8000 mm or less, further preferably 7000 mm or less, and particularly preferably 6000 mm or less.

[0030] The average height of the bottom surface in the hydraulic washing column refers to the average height of the entire bottom surface in the hydraulic washing column in the state of use of the hydraulic washing column.

[0031] The distance from the lower end of the filter to the average height of the bottom surface in the hydraulic washing column can be the distance from the lower end of any filter to the average height of the bottom surface in the hydraulic washing column when there are a plurality of filters in the hydraulic washing column, but it is preferably set to the distance from the lower end of the filter located at the lowermost side to the average height of the bottom surface in the hydraulic washing column.

[0032] The pipe that extracts the mother liquor connected to the filter is usually disposed on the upper side of the filter. The extracted mother liquor can be recirculated, whereby the yield of the compound can be improved. For example, the extracted mother liquor can be set to a part of the crystal slurry supplied to the hydraulic washing column.

[0033] The material of the filter is not particularly limited, and for example, can be composed of a metal such as stainless steel, composed of a resin such as polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), or the like, and is preferably the latter. In addition, the material of the pipe is not particularly limited, and for example, can be composed of a metal or an alloy.

[0034] The purification device of the present application can further include a dummy pipe connected to the filter that filters the slurry containing crystals in the hydraulic washing column.

[0035] The dummy pipe is generally disposed on the lower side of the filter. In addition, the material of the dummy pipe is not particularly limited, but for example, is preferably composed of a resin such as polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), perfluoroalkoxy alkane (PFA), or the like.

[0036] By further including the dummy pipe, a portion where crystals are difficult to accumulate in the lower part of the filter can be excluded, and as a result, a crystallization bed can be uniformly and firmly formed.

[0037] The length of the dummy pipe is appropriately set, but is preferably 1000 mm or more, more preferably 1500 mm or more, and more preferably 2000 mm or more. In addition, the length of the dummy pipe is preferably 10000 mm or less, more preferably 8000 mm or less, further preferably 7000 mm or less, and particularly preferably 6000 mm or less, in consideration of the scale and efficiency of the device. In addition, it is preferable to provide the dummy pipe from the lower end of the filter to the vicinity of the bottom surface of the hydraulic column.

[0038] An instrumented device such as a thermometer (multi-point, etc.), a pressure gauge, an interface gauge (optical, etc.), or the like can be provided on the main body or the periphery of the hydraulic washing column.

[0039] In addition, the hydraulic washing column itself can be in a temperature-regulated housing (generally in a building, etc.).

[0040] The purification device of the present application preferably further includes an extraction line connecting an extraction port of the circulating slurry containing crystals in the hydraulic washing column to a device that melts, and a return line connecting the device that melts to the return port in the hydraulic washing column.

[0041] The extraction line is preferably provided in the vicinity of the bottom surface of the hydraulic washing column.

[0042] In the use of the purification device of the present application, the circulating slurry or the circulating liquid containing the melting liquid is circulated in the extraction line and the return line. In this specification, the circulation path is also referred to as a melt circuit.

[0043] The part of the circulating slurry flow in the circulation path is the part from the start of the circulating slurry by introducing the crystal into the hydraulic cleaning column to the melting of the crystal contained in the circulating slurry. For example, in the above-mentioned melt circuit, the circulating liquid returned from the return port 25 at the bottom of the hydraulic cleaning column is mixed with the crystal in the hydraulic cleaning column, thereby becoming the circulating slurry, and flows through the path (extraction line 21) between the extraction port 20 of the circulating slurry and the melting device 22.

[0044] The purification device of the present application preferably includes a mechanism for extracting the crystal from the crystallization bed in the hydraulic cleaning column.

[0045] The mechanism for extracting the crystal from the crystallization bed is not particularly limited, and examples include the rotor blade or the scraper described in Japanese Patent Application Laid-Open No. 2005-509009, the mechanism using liquid dynamic pressure described in European Patent No. 1469926, and the like, and one or two or more of them can be used. In the case of using the above-mentioned rotor blade or scraper, the rotation speed is preferably 20 rpm to 60 rpm, and the material is preferably a metal such as stainless steel.

[0046] As the above-mentioned melting device, a heater is generally used. As the heater, examples include a configuration for efficiently transferring heat to the slurry containing the crystal, such as a vertical multi-tube heat exchanger, a horizontal multi-tube heat exchanger, a double-pipe heat exchanger, a spiral heat exchanger, a plate heat exchanger, a coil heat exchanger, an electric heater, and the like. It is preferable that the heater be provided in the melt circuit, and the circulating slurry (after melting, the circulating liquid) be circulated by a pump provided in the melt circuit in a forced circulation system.

[0047] The purification device of the present application can also include a mechanism (return mechanism) for returning a part of the circulating liquid containing the melted liquid obtained by the device for melting the crystal to the hydraulic cleaning column.

[0048] The above-mentioned return mechanism is a mechanism for separating a part of the above-mentioned circulating liquid from the other part of the circulating liquid and returning it to the hydraulic cleaning column, and examples include a branch path in the case where a product extraction line is branched from a return line connecting the above-mentioned melting device and the above-mentioned return port and connected to a product extraction port. As the branch path, for example, a T-shaped path (cross-shaped path) can be mentioned.

[0049] It is preferable that the above-mentioned return mechanism include a mechanism for returning a part of the circulating liquid containing the melted liquid obtained by the device for melting the crystal to the hydraulic cleaning column so that at least a part of it becomes the cleaning liquid for cleaning the crystal.

[0050] Preferably, the above-mentioned return port is provided at the bottom of the hydraulic washing column to enable upward return of the circulating liquid. The above-mentioned return mechanism can be, for example, a combination of the above-mentioned branch line and the return port provided at the bottom of the hydraulic washing column.

[0051] The purification device of the present application preferably further includes a product extraction port. For example, the purification device of the present application more preferably further includes a product extraction line branched from the return line connecting the above-mentioned melting device to the above-mentioned return port and a product extraction port connected to the product extraction line.

[0052] In Figure 1 An example of the purification device of the present application is shown in FIG. 1. A slurry containing crystals 11a is supplied into a hydraulic washing column 1 via a supply line 11 (including a pipe 4) for supplying the slurry containing crystals to the hydraulic washing column, and although not shown, the crystals are accumulated in the lower portion of the hydraulic washing column 1 to form a crystallization bed. A filter 2 for filtering the slurry containing crystals in the hydraulic washing column and a pipe 3 for extracting a mother liquor connected to the filter are provided in the hydraulic washing column 1, and the mother liquor 12 can be recovered / reused from the slurry containing crystals.

[0053] In addition, the crystals are extracted from the bottom of the hydraulic washing column 1 together with the circulating liquid circulating in the melt circuit through the bottom of the hydraulic washing column 1, as a circulating slurry containing crystals, and are transferred to a device 22 for melting the crystals contained in the circulating slurry via an extraction line 21 connecting an extraction port 20 of the circulating slurry to the melting device 22. A part of the circulating liquid containing the melting liquid obtained by melting by the melting device 22 is returned to the hydraulic washing column 1 via a return line 24 connecting the melting device 22 to the above-mentioned return port 25, and a part of the returned circulating liquid becomes a washing liquid for washing the crystals, and the remaining part of the returned circulating liquid is extracted from the extraction port 20 of the circulating slurry together with the crystals and recirculated in the melt circuit. In addition, a part of the circulating liquid containing the melting liquid obtained by melting by the melting device 22 is branched from the return line 24 as a purified product 23a, and is extracted from the purification device via a product extraction line 23 connected to a product extraction port.

[0054] The purification device of the present application can further include a mechanism for controlling the amount of return of the above-mentioned circulating liquid.

[0055] The purification device of the present application, by further including a mechanism (control mechanism) for controlling the amount of return of the above-mentioned circulating liquid, for example, can adjust the amount of return of the above-mentioned circulating liquid, and can efficiently obtain a product with excellent separation efficiency of impurities as needed.

[0056] As the above-mentioned control mechanism, for example, a valve or the like installed in the line of the above-mentioned return mechanism (branch line) portion can be cited.

[0057] The control mechanism can directly control the amount of the circulating liquid, or can indirectly control the amount of the circulating liquid.

[0058] When the control mechanism directly controls the amount of the circulating liquid, a valve (not shown) installed in the return line 24 shown in FIG. 1 can be cited as the control mechanism. Figure 1 The control mechanism can directly control the amount of the circulating liquid, or can indirectly control the amount of the circulating liquid.

[0059] When the control mechanism indirectly controls the amount of the circulating liquid, a valve (not shown) installed in the product extraction line 23 connected to the product extraction port (not shown) can be cited as the control mechanism. By adjusting the valve installed in the product extraction line 23, the amount of the circulating liquid in the return line 24 can be controlled.

[0060] Note that a valve can be provided in both the product extraction line 23 and the return line 24.

[0061] Further, by providing flow meters in the supply line 11 (including the pipe 4) that supplies the slurry 11a containing crystals to the hydraulic washing column, the product extraction line 23, and the return line 24, the valves can be controlled based on the flow rates. In addition, a multi-point temperature meter can be provided in the hydraulic washing column, and the valves can be controlled based on the internal temperature.

[0062] The purification device of the present application preferably further includes a bypass line that connects the extraction line and the return line. That is, the purification device of the present application preferably further includes an extraction line that connects the extraction port and the melting device, a return line that connects the melting device and the return port, and a bypass line that connects the extraction line and the return line.

[0063] By including the bypass line that connects the extraction line and the return line, the flow rate of the circulating liquid returned to the hydraulic washing column and the flow rate of the circulating slurry and / or the circulating liquid circulated in the melting device can be controlled independently of each other, and thus the entire device can be efficiently operated, and a high-quality product can be more efficiently produced.

[0064] The purification device of the present application, in the mode including the bypass line, can further include a distribution mechanism that controls the flow rate of the bypass line.

[0065] As the distribution mechanism, a valve or the like installed in the return line and / or the bypass line can be cited. In addition, a valve (a three-way valve or the like) that switches the flow path can be provided at the T-shaped portion of the return line and the bypass line. When the valve that switches the flow path is provided at the T-shaped portion, the valve or the like can or can not be installed in the return line and / or the bypass line.

[0066] In the case where the distribution mechanism is a valve 124b that connects the branch point at which the bypass line branches from the return line to the return port, the amount of return of the bypass line can be controlled by adjusting the valve. Figure 2

[0067] In the case where the distribution mechanism is a valve installed in the bypass line, the flow rate of the circulating liquid in the bypass line can be directly controlled. Note that in the present embodiment, a case where a valve V is installed in the bypass line 126 is exemplified. Figure 2

[0068] The purification apparatus of the present application can further include a portion (124a) that connects the melting device to the branch point at which the bypass line branches from the return line, a portion (124b) that connects the branch point at which the bypass line branches from the return line to the return port, and a device that measures the flow rates of the bypass line. Figure 2 Figure 2

[0069] The device that measures the flow rates is, for example, a flow meter installed at a predetermined position of the return line or the bypass line.

[0070] Flow meters can be installed at all of the positions (124a, 124b, and 126), or the flow rate at one of the positions can be calculated from the flow rates measured at the other two positions. Figure 2

[0071] The extraction line, the return line, and the bypass line can be provided with a heating mechanism, or a heating mechanism can be provided for all of the lines, or a heating mechanism can be provided for any one of the lines.

[0072] As the heating mechanism, a heat retaining mechanism, such as a jacket using a hot medium such as water, a steam passage, an electric heater, or the like, can be used, and one or two or more of these can be used.

[0073] The heating temperature of the heating mechanism is appropriately set according to the melting point of the compound, and can be appropriately adjusted, for example, in the range of 10°C to 100°C.

[0074] For example, in the case where the compound is a (meth)acrylic acid, the heating temperature of the heating mechanism is preferably 15°C or higher, and more preferably 18°C or higher. In addition, the heating temperature is preferably 50°C or lower, and more preferably 40°C or lower.

[0075] The heating temperature of the heating mechanism is the temperature of the heating mechanism when the heating mechanism is supplied with a hot medium to be heated, or the temperature of the hot medium.

[0076] ​​​​​The size of the hydraulic cleaning column included in the purification device of the present application is not particularly limited, and for example, the inner diameter of the column (in the crystal chamber) is preferably 30 mm to 2000 mm. In addition, the height thereof is preferably 1500 mm to 15000 mm.

[0077] The size of the filter for filtering the slurry containing the crystals in the hydraulic cleaning column of the present application is not particularly limited, and for example, the inner diameter thereof is preferably 10 mm to 30 mm. In addition, the height thereof is preferably 20 mm to 300 mm.

[0078] The filter described above can be exemplified by, for example, a plurality of circular holes, slits (cutouts), rectangular holes. In addition, the shape thereof is not particularly limited, and can be exemplified by the same shape as a pipe, such as a cylindrical shape, and the like.

[0079] In the case where the hole shape of the filter is circular, the diameter thereof is appropriately adjusted according to the size of the crystals, and for example, is preferably 50 μm to 500 μm. In addition, the number of holes thereof is not particularly limited, and for example, can be adjusted according to the pressure loss, and the like.

[0080] The pipe for extracting the mother liquor connected to the filter described above is generally disposed on the upper side of the filter.

[0081] The pipe for extracting the mother liquor connected to the filter described above is not particularly limited, and for example, in the case of an industrial-scale hydraulic cleaning column, it is preferable that 1 m2of the cross-sectional area of the hydraulic cleaning column be provided with 50 to 350 pipes. 2 The pipes are connected in parallel.

[0082] The purification device of the present application can also further include a mechanism for heating the outer wall surface of the hydraulic cleaning column described above.

[0083] The mechanism for heating the outer wall surface of the hydraulic cleaning column described above is not particularly limited, and can be exemplified by a heat medium, a steam passage, an electric passage, a publicly known heater for adjusting the ambient temperature of the column, and the like, and for example, can be performed by heating a part of the hydraulic cleaning column by a heat medium, and the like, but is preferably performed by heating substantially the entire hydraulic cleaning column (jacket type).

[0084] In the case where the mechanism for heating described above is, for example, a jacket type, the material thereof is not particularly limited, and can be either a metal (for example, SUS, carbon steel) or a resin.

[0085] A heat insulating material, a passage, and the like can be further provided on the outside of the jacket described above.

[0086] The configuration of the jacket described above is not particularly limited.

[0087] The inside of the jacket described above is not particularly limited, but a configuration for promoting heat conduction, such as a baffle, can be provided.

[0088] The average thickness of the above-mentioned sheath (the width of the space of the portion where the heat medium flows) is preferably, for example, 5 mm to 200 mm.

[0089] The heat flux through the wall surface of the hydraulic cleaning column via the above-mentioned sheath is preferably more than 100 W / m 2 , more preferably more than 200 W / m 2 , and further preferably more than 500 W / m 2 .

[0090] The upper limit of the heat flux through the wall surface of the hydraulic cleaning column via the above-mentioned sheath is not particularly limited and is usually 4000 W / m 2 or less.

[0091] In addition, the difference between the melting point of the above-mentioned compound and the temperature of the heat medium supplied to the above-mentioned sheath is preferably 1°C or more, more preferably 2°C or more, and further preferably 5°C or more. In addition, the upper limit thereof is not particularly limited and is usually 20°C.

[0092] A peephole (an observation window) and a hand hole (a hole for putting a hand into the inside at the time of maintenance) can also be provided to the side wall of the above-mentioned sheath. In this case, they can be covered with a cover. The number of the peepholes and the hand holes provided is not limited in the case where they are provided.

[0093] Note that, as the above-mentioned heat medium, there is no particular limitation and water, an antifreeze solution, methanol water (a methanol aqueous solution), a gas, and the like can be given. The above-mentioned heat medium can be appropriately selected in consideration of the freezing point of the compound to be purified and the like.

[0094] The number of the pipe for supplying the slurry containing the crystals to the hydraulic cleaning column and the supply nozzle (a slurry supply port) which can be connected to the top end of the pipe is not particularly limited and can be one or a plurality of (in Figure 1 , Figure 2 , a case where the pipe for supplying the slurry containing the crystals to the hydraulic cleaning column is one is shown).

[0095] The above-mentioned supply nozzle can have a dispersion mechanism which disperses the slurry to the top end thereof.

[0096] The above-mentioned hydraulic cleaning column can further include a dispersion chamber and a central discharge body (see Japanese Patent Application Laid-Open No. 2005-509010).

[0097] (Method for producing a compound of the present application)

[0098] The present application is also a method for producing a compound, wherein the method comprises: a step of feeding a slurry containing crystals of the compound to a hydraulic washing column; a step of extracting a circulating slurry containing the crystals from the hydraulic washing column, and dissolving the crystals contained in the extracted circulating slurry; a step of returning a part of a circulating liquid containing a solution obtained in the dissolving step to the hydraulic washing column; and a step of filtering the slurry containing the crystals in the hydraulic washing column using a filter, and extracting a mother liquor using a pipe connected to the filter, wherein a distance from a lower end of the filter to an average height of a bottom surface in the hydraulic washing column is 1000 mm or more.

[0099] In the method for producing a compound of the present application, a distance from a lower end of the filter to an average height of a bottom surface in the hydraulic washing column is determined, and, instead of this, a space velocity (SV: Space velocity) of a crystallization bed on a lower side than the filter in the hydraulic washing column can also be determined.

[0100] For example, the present application is also a method for producing a compound, wherein the method comprises: a step of feeding a slurry containing crystals of the compound to a hydraulic washing column; a step of extracting a circulating slurry containing the crystals from the hydraulic washing column, and dissolving the crystals contained in the extracted circulating slurry; a step of returning a part of a circulating liquid containing a solution obtained in the dissolving step to the hydraulic washing column; and a step of filtering the slurry containing the crystals in the hydraulic washing column using a filter, and extracting a mother liquor using a pipe connected to the filter, wherein a space velocity (1 / h) of a crystallization bed on a lower side than the filter in the hydraulic washing column is 1 or more and 20 or less.

[0101] The space velocity (1 / h) of the crystallization bed on the lower side than the filter in the hydraulic washing column means a space velocity of the crystallization bed from a height at which the lower end of the filter is present to extraction of the crystals from an extraction port of the circulating slurry containing the crystals provided in the hydraulic washing column. That is, the space velocity (1 / h) can also be said to represent a flow rate (m 3 / h) of the crystals with respect to a volume (m 3 / h) in the hydraulic washing column from the height of the lower end of the filter to the bottom surface in the hydraulic washing column.

[0102] The space velocity (1 / h) is, for example, calculated from a traveling speed of the crystallization bed measured by a scope provided on a side surface of the hydraulic washing column and a distance from the lower end of the filter to an average height of the bottom surface in the hydraulic washing column, by the following formula (1).

[0103] Space velocity = traveling speed of the crystallization bed (mm / h) / distance (mm) from the lower end of the filter of the liquid pressure washing column to the average height of the bottom surface in the column (1)

[0104] Alternatively, for a substance for which the weight ratio of the crystals of the crystallization bed to the mother liquor is known, the space velocity is calculated by the following equation (2).

[0105] Space velocity = crystal supply amount / weight ratio of the crystals of the crystallization bed / (crystal density x weight ratio of the crystals of the crystallization bed + mother liquor density x (1 - weight ratio of the crystals of the crystallization bed)) / volume from the lower end of the filter of the liquid pressure washing column to the bottom surface in the column (2)

[0106] Note that in the above equation (2), the units of the respective amounts are as described below.

[0107] Crystal supply amount (t / h)

[0108] Weight ratio of the crystals of the crystallization bed (unitless)

[0109] Crystal density (t / m 3 )

[0110] Mother liquor density (t / m 3 )

[0111] Volume from the lower end of the filter of the liquid pressure washing column to the bottom surface in the column (m 3 )

[0112] The weight ratio of the crystals of the crystallization bed is the ratio of the weight of the crystals in the slurry when the weight of the slurry is taken to be 1. Note that the crystallization bed is in a state rich in crystals, and is different from the slurry supplied to the liquid pressure washing column (the supplied slurry). The crystal density is the density of the crystals themselves.

[0113] The above space velocity (1 / h) is more preferably 12 or less, further preferably 8 or less, and particularly preferably 6 or less.

[0114] The above space velocity (1 / h) is more preferably 1.25 or more, and further preferably 1.5 or more.

[0115] In the method for producing the compound of the present application, the ratio of the weight of the mother liquor to the weight of the crystals in the slurry containing the crystals supplied to the liquid pressure washing column per unit time is preferably 1 or more, more preferably 1.5 or more, further preferably 2.3 or more, and particularly preferably 4 or more.

[0116] In addition, the ratio of the weight of the mother liquor to the weight of the crystals in the slurry containing the crystals supplied to the liquid pressure washing column per unit time is preferably 99 or less, more preferably 32 or less, and further preferably 19 or less.

[0117] For example, in the method for producing the compound of the present application, the ratio of the weight of the mother liquor to the weight of the crystals in the slurry containing the crystals supplied to the hydraulic washing column per unit time is preferably 4 or more and 19 or less.

[0118] If the ratio of the weight of the mother liquor to the weight of the crystals is 4 or more, the amount of the mother liquor in the crystalline bed stacked on the upper portion of the filter increases, the ratio of the crystals in the crystalline bed increases, the mother liquor containing impurities is easily removed, and the washing efficiency is further improved. In addition, if the ratio is 19 or less, the mass of the mother liquor per unit time of the amount of the crystals supplied is small, the pump can be made compact, and the pressure in the device is small, and the pressure resistance of the device does not need to be further improved. Note that the ratio of the weight of the crystals in the crystalline bed is about 50% to 85%.

[0119] Note that, in the present specification, the slurry containing the crystals supplied to the hydraulic washing column per unit time refers to the entire slurry containing the crystals supplied to the hydraulic washing column during the unit time (1 hour).

[0120] In addition, in the case where a part of the mother liquor extracted from the hydraulic washing column is recirculated in the hydraulic washing column, the weight of the mother liquor in the slurry containing the crystals supplied to the hydraulic washing column per unit time includes the weight of the mother liquor.

[0121] In the method for producing the compound of the present application, the above-mentioned supplying step, the above-mentioned dissolving step, and the above-mentioned recirculating step are basically performed in order for the purification target (for example, as shown in Figure 1 After the slurry containing the crystals 11a is supplied to the inside of the hydraulic washing column 1 via the supply line 11 / pipe 4, the recirculated slurry containing the crystals is extracted from the recirculated slurry extraction port 20 at the bottom of the hydraulic washing column 1, and the recirculated slurry is dissolved in the device 22 for dissolving the crystals contained in the recirculated slurry by connecting the recirculated slurry extraction port 20 and the device 22 for dissolving via the extraction line 21. A part of the recirculated liquid containing the dissolved liquid obtained by the device 22 for dissolving is recirculated into the hydraulic washing column 1 via the recirculation line 24 connected to the recirculation port 25. Note that the other recirculated liquid is extracted as a product 23a from the purification device via the product extraction line 23 branched from the recirculation line 24. Hereinafter, the supplying step, the dissolving step, and the recirculating step will be described in order, and then the step of extracting the mother liquor and other steps will be described. Note that in the continuous purification process, generally, when viewed as a whole, the steps are performed at the same time.

[0122] In the present specification, "compound" refers to a compound obtained by the production method of the present application, and does not refer to a raw material, a by-product, a solvent in the production method of the present application. The "compound" can be referred to as "target compound" or "target substance". In the present specification, "impurity" refers to a component other than the "compound", such as a raw material, a by-product, a solvent.

[0123] <Process of supplying>

[0124] In the above-mentioned process of supplying, a slurry containing crystals of the compound is supplied to the hydraulic washing column. The slurry containing the crystals is a suspension of the crystals of the compound and a mother liquor, in other words, the liquid portion of the slurry containing the crystals of the compound supplied to the hydraulic washing column is the mother liquor. Note that, as described later, the slurry containing the crystals can be obtained by generating the crystals in a solution containing the compound (for example, an aqueous (meth)acrylic acid solution or a crude (meth)acrylic acid solution), but the solution containing the compound can be either a self-prepared solution or a solution supplied from elsewhere. Note that, the solution containing the compound referred to herein also includes a crude compound.

[0125] In the slurry containing the crystals supplied to the above-mentioned hydraulic washing column, the mass ratio of the crystals is preferably 1 mass% or more, more preferably 3 mass% or more, and further preferably 5 mass% or more.

[0126] The mass ratio of the above-mentioned crystals is preferably 50 mass% or less, more preferably 40 mass% or less, further preferably 30 mass% or less, and particularly preferably 20 mass% or less.

[0127] Note that, in the present specification, in the case of merely referring to "the slurry containing the crystals supplied to the hydraulic washing column", the slurry containing the crystals supplied to the hydraulic washing column refers to the slurry containing the crystals immediately before being supplied to the hydraulic washing column, for example, refers to the slurry containing the crystals in a pipe for supplying the slurry containing the crystals to the hydraulic washing column.

[0128] The slurry containing the crystals supplied to the above-mentioned hydraulic washing column preferably contains the above-mentioned compound in the mother liquor thereof. As the above-mentioned mother liquor, the above-mentioned compound, an aqueous solution of the above-mentioned compound, and the like can be exemplified. Note that, the above-mentioned mother liquor generally includes impurities other than the above-mentioned compound and water.

[0129] In the production method of the compound of the present application, the purity (mass ratio) of the above-mentioned compound in the mother liquor of the slurry containing the crystals supplied to the above-mentioned hydraulic washing column is preferably 99 mass% or less. Thereby, the effect of the present application is remarkably exhibited.

[0130] The mass ratio of the compound in the above mother liquor is more preferably 98 mass% or less, further preferably 97 mass% or less, and particularly preferably 96 mass% or less.

[0131] The mass ratio of the compound in the above mother liquor is preferably 85 mass% or more, more preferably 88 mass% or more, and further preferably 90 mass% or more.

[0132] In the production method of the present application, the melting point of the above compound is preferably 0°C to 80°C, more preferably 1°C to 50°C, further preferably 3°C to 40°C, and particularly preferably 5°C to 20°C.

[0133] In addition, as the compound having the above melting point, a polymerizable compound having a reactive double bond is preferable.

[0134] In the production method of the present application, the above compound is more preferably an unsaturated carboxylic acid, further preferably a (meth)acrylic acid, and particularly preferably an acrylic acid. In the present specification, the (meth)acrylic acid is acrylic acid and / or methacrylic acid.

[0135] In the above mother liquor, the mass ratio of water is more preferably 0.1 mass% or more, more preferably 0.5 mass% or more, and further preferably 1 mass% or more.

[0136] In the above mother liquor, the mass ratio of water is preferably 8 mass% or less, more preferably 6 mass% or less, and further preferably 4 mass% or less.

[0137] In the above mother liquor, the mass ratio of impurities other than the above compound and water is preferably 0.1 mass% or more, more preferably 0.4 mass% or more, and further preferably 0.8 mass% or more, from the viewpoint that the effect of the present application becomes significant.

[0138] In the above mother liquor, the mass ratio of impurities other than the above compound and water is preferably 8 mass% or less, more preferably 6 mass% or less, and further preferably 4 mass% or less.

[0139] In the case where the above compound is a (meth)acrylic acid, as the impurities other than the above compound and water, for example, acetic acid, furfural, and the like can be exemplified.

[0140] In this case, in the above mother liquor, the mass ratio of acetic acid is preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and further preferably 0.7 mass% or more, from the viewpoint that the effect of the present application becomes significant.

[0141] In the above mother liquor, the mass ratio of acetic acid is preferably 8 mass% or less, more preferably 6 mass% or less, and further preferably 4 mass% or less.

[0142] In the case where the above-mentioned compound is a (meth)acrylic acid, the mass ratio of the furfural in the above-mentioned mother liquor is more preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.1% by mass or more, from the viewpoint that the effect of the present application becomes significant.

[0143] The mass ratio of the furfural in the above-mentioned mother liquor is preferably 2% by mass or less, more preferably 1% by mass or less, and further preferably 0.5% by mass or less.

[0144] The supply rate of the slurry containing the crystals in the above-mentioned supply process is not particularly limited, but is, for example, 0.2 x 10 3 kg / h to 4.0 x 10 5 kg / h, for an industrial-scale hydraulic washing column.

[0145] The supply temperature of the slurry containing the crystals in the above-mentioned supply process can be appropriately set according to the melting point or the like of the above-mentioned compound, but can be appropriately adjusted, for example, in the range of 0°C to 80°C.

[0146] The supply temperature of the slurry containing the crystals is preferably 5°C to 13°C, and more preferably 6°C to 12°C, for example, in the case where the above-mentioned compound is a (meth)acrylic acid.

[0147] The supply temperature of the above-mentioned slurry containing the crystals is the temperature of the mother liquor in the slurry containing the crystals immediately before the supply to the above-mentioned hydraulic washing column.

[0148] <Melting process>

[0149] In the above-mentioned melting process, the circulating slurry containing the crystals is extracted from the hydraulic washing column, and the crystals contained in the extracted circulating slurry are melted.

[0150] The crystals originate from a crystallization bed formed in the lower portion of the hydraulic washing column. In the extraction of the crystals, the above-mentioned mechanism for extracting the crystals from the crystallization bed in the hydraulic washing column can be used.

[0151] In the extraction of the crystals, generally, the circulating liquid is also extracted, as the circulating slurry containing the crystals, and is supplied to the melting process.

[0152] The above-mentioned circulating liquid is extracted from the hydraulic washing column as the circulating slurry containing the crystals, and thereafter, as the circulating liquid containing the melting liquid obtained by the melting process, a part thereof is returned to the hydraulic washing column, and thereby circulates through the inside of the hydraulic washing column, in other words, flows through a circulation path in the inside of the hydraulic washing column. Note that, in the present specification, the liquid component in the circulating slurry flowing through the circulation path is also referred to as the circulating liquid.

[0153] Here, the circulating slurry refers to a suspension of crystals of the compound and a circulating liquid, which flows in the circulating path.

[0154] For example, in the circulating slurry containing crystals extracted from the above-described hydraulic cleaning column, the mass ratio of the crystals is preferably 0.5 mass% or more, more preferably 1 mass% or more, further preferably 3 mass% or more, and particularly preferably 5 mass% or more.

[0155] The mass ratio of the above-described crystals is preferably 40 mass% or less, more preferably 30 mass% or less, further preferably 20 mass% or less, and particularly preferably 10 mass% or less.

[0156] Note that, in the present specification, the circulating slurry containing crystals extracted from the above-described hydraulic cleaning column refers to the circulating slurry containing crystals immediately after extraction from the hydraulic cleaning column, and for example refers to the circulating slurry containing crystals in an extraction line (pipe) connecting the extraction port of the circulating slurry and the apparatus for melting.

[0157] The extraction rate of the circulating slurry containing crystals extracted from the hydraulic cleaning column is not particularly limited, but for a hydraulic cleaning column of an industrial scale, for example, is 2 x 10 3 kg / h to 5 x 10 5 kg / h.

[0158] The melting of the extracted crystals can be performed using a heater. As the heater, a configuration that efficiently transfers heat to the slurry containing crystals can be exemplified, such as a vertical multi-tube heat exchanger, a horizontal multi-tube heat exchanger, a double-pipe heat exchanger, a spiral heat exchanger, a plate heat exchanger, a coil heat exchanger, an electric heater, and the like. It is preferable that the heater be provided in the melt circuit, and that the circulating slurry (after melting, the circulating liquid) be circulated by a pump provided in the melt circuit in a forced circulation system.

[0159] The heating temperature in the above-described melting process can be appropriately set according to the melting point of the above-described compound, and for example, can be appropriately adjusted in the range of 10°C to 100°C.

[0160] For example, in the case where the above-described compound is a (meth)acrylic acid, the heating temperature in the above-described melting process is preferably 15°C or more, and more preferably 18°C or more. In addition, the heating temperature is preferably 50°C or less, and more preferably 40°C or less.

[0161] In the case where a heating medium is supplied to the apparatus for melting to perform heating, the heating temperature in the above-described melting process is the supply temperature of the heating medium.

[0162] Further, the temperature of the circulating solution containing the dissolved solution discharged from the outlet of the above-mentioned dissolving step (dissolving apparatus) is preferably set to a temperature of 1 to 10°C higher than the melting point of the circulating solution containing the dissolved solution obtained by the dissolving step (e.g., the circulating solution containing the dissolved solution obtained by heat exchange or the like at this time by dissolving the crystals in the slurry).

[0163] The dissolving time in the above-mentioned dissolving step is appropriately determined to the extent that the crystals are sufficiently dissolved.

[0164] In the production method of the present application, the above-mentioned dissolving step is performed using a dissolving apparatus for dissolving the crystals, and the linear velocity of the circulating slurry or the circulating solution containing the dissolved solution in the dissolving apparatus is preferably 0.05 to 4 m / s.

[0165] The linear velocity is more preferably 0.1 m / s or more. By this, the heat transfer performance in the dissolving apparatus is more excellent. That is, the greater the linear velocity, the better the circulating slurry or the circulating solution containing the dissolved solution is mixed, the heat transfer surface is renewed, and as a result, the heat transfer is promoted.

[0166] The linear velocity is more preferably 3 m / s or less, and further preferably 2 m / s or less. By this, the increase in the pressure loss in the dissolving apparatus due to the excessively large linear velocity can be prevented, and stable operation can be performed.

[0167] The linear velocity can be calculated by measuring the volume flow rate of the circulating slurry or the circulating solution containing the dissolved solution in the above-mentioned dissolving apparatus with a flow meter, and dividing the cross-sectional area of the heat exchange portion through which the circulating slurry or the circulating solution containing the dissolved solution flows in the dissolving apparatus. Further, in the case where the linear velocity varies in the dissolving apparatus, the average linear velocity corresponding to the ratio of the heat transfer area can be considered.

[0168] <Return step>

[0169] The above-mentioned return step returns a part of the circulating solution containing the dissolved solution obtained by the above-mentioned dissolving step to the hydraulic washing column.

[0170] The above-mentioned circulating solution contains the dissolved solution obtained by the above-mentioned dissolving step. That is, the crystals in the extracted circulating slurry are dissolved to become the dissolved solution, and the suspended circulating slurry becomes the non-suspended circulating solution.

[0171] The dissolved solution obtained by the above-mentioned dissolving step means the liquid obtained by dissolving the crystals contained in the circulating slurry extracted from the hydraulic washing column in the dissolving step, and does not include the circulating solution (liquid component) contained in the circulating slurry.

[0172] A part of the circulating solution containing the molten solution obtained in the above-mentioned melting step is returned to the hydraulic washing column, and the returned part of the circulating solution becomes the washing solution for washing the crystals in the hydraulic washing column.

[0173] The above-mentioned washing solution refers to a part of the circulating solution returned to the hydraulic washing column, which, after being returned to the hydraulic washing column, is extracted from the extraction port of the hydraulic washing column, not recirculated in the circulating path, but flows, for example, through the interstices of the crystals of the crystallization bed of the hydraulic washing column, in a countercurrent manner (preferably upward) with respect to the moving direction of the crystals, to wash the crystals in the hydraulic washing column.

[0174] In the above-mentioned returning step, in the case where a part of the above-mentioned circulating solution is returned to the hydraulic washing column, it is preferable to return in a countercurrent manner with respect to the moving direction of the crystals (bed), which can be appropriately determined depending on the densities of the washing solution and the crystals. For example, in the case where the density of the crystals is higher than that of the mother liquor, the circulating solution is preferably returned upward. Here, upward preferably means substantially vertically upward with respect to the horizontal plane. Thus, the crystals can be efficiently washed.

[0175] The returning ratio in the above-mentioned returning step is not particularly limited, and is preferably 1 mass% or more and 80 mass% or less. The returning ratio referred to here means the mass ratio of the washing solution for washing the crystals with respect to 100 mass% of the molten solution. Note that the molten solution is included in the circulating solution, and thus cannot be separated as the molten solution.

[0176] In other words, in the above-mentioned returning step, it is preferable to return a part of the circulating solution containing the molten solution returned to the hydraulic washing column to the hydraulic washing column, and in the circulating solution returned in this returning step, an amount corresponding to 1 mass% or more and 80 mass% or less of the above-mentioned molten solution becomes the washing solution for washing the crystals.

[0177] Note that, as described above, the above-mentioned washing solution, after being returned to the hydraulic washing column, is not recirculated in the circulating path, but is removed from the circulating solution flowing in the circulating path. The product is also removed by being extracted from the circulating solution flowing in the above-mentioned circulating path. On the other hand, the crystals are extracted from the hydraulic washing column and introduced into the circulating solution circulating in the circulating path. The part removed from the circulating path and the part introduced into the circulating path are balanced in continuous operation, and the sum of the amount of the above-mentioned washing solution and the amount of the extracted product is equal to the amount of the crystals extracted from the hydraulic washing column, i.e., the amount of the molten solution obtained in the melting step. Thus, the amount of the above-mentioned washing solution is also the amount obtained by subtracting the extraction amount of the product from the amount of the molten solution of the extracted crystals.

[0178] The proportion of the return in the above-mentioned returning step can be determined by converting the amount of crystals supplied to the dissolving step from the slurry flow rate supplied to the hydraulic washing column and the slurry concentration calculated from the sampling, densitometry, freezing point of the mother liquor, etc., measuring the flow rate of the circulating liquid extracted as the product using a flow meter device, or calculating from the impurity concentration in the mother liquor of the slurry supplied to the hydraulic washing column (hereinafter, also referred to as the supplied slurry), the extracted mother liquor, and the extracted product.

[0179] Note that the product extraction rate of the extracted product in the above-mentioned returning step is 5 kg / h to 4.0 x 10 4 kg / h for an industrial-scale hydraulic washing column.

[0180] In the production method of the present application, the outer wall surface of the above-mentioned hydraulic washing column can also be heated by a heating medium or the like, and the temperature of the heating medium used for this heating can be appropriately set according to the substance to be treated, i.e., the compound that is the target.

[0181] As the above-mentioned heating medium, any liquid or gas can be used, and examples thereof include water, an antifreeze solution, methanol water (methanol aqueous solution), a gas, etc. The above-mentioned heating medium can be appropriately selected in consideration of the freezing point of the compound to be purified, etc.

[0182] By heating the outer wall surface of the above-mentioned hydraulic washing column, freezing can be prevented, and the above-mentioned compound can be more stably produced.

[0183] The above-mentioned heating can also be performed by heating a part of the above-mentioned hydraulic washing column by a heating medium or the like, but is preferably performed by heating substantially the entire body of the above-mentioned hydraulic washing column (jacket type).

[0184] Note that the above-mentioned hydraulic washing column is operated under substantially pressurized conditions (preferably, in the range of 0.05 MPa to 1.0 MPa).

[0185] <Step of extracting the mother liquor>

[0186] The production method of the present application includes a step of extracting the mother liquor using a filter to filter the slurry containing crystals in the hydraulic washing column, and a pipe connected to the filter. In the above-mentioned step of extracting the mother liquor, a part of the above-mentioned washing liquid is also extracted together with the mother liquor. Therefore, the extracted mother liquor includes a part of the above-mentioned washing liquid.

[0187] The extracted mother liquor can be recycled and reused. By reusing the extracted mother liquor, for example, as at least a part of the slurry containing crystals supplied to the hydraulic washing column, the quality of the above-mentioned compound can be further improved.

[0188] Note that, in the case where the density of the crystal is greater than that of the mother liquor, the mother liquor in the slurry supplied in the supplying step flows from the top to the bottom, collides with the cleaning liquid flowing from the bottom to the top and is pushed back, and is extracted through the filter.

[0189] The material of the filter is not particularly limited, and for example, can be composed of a metal such as stainless steel, or a resin such as polytetrafluoroethylene (PTFE) or polyether ether ketone (PEEK), with the latter being preferred. In addition, the material of the pipe is not particularly limited, and is preferably composed of a metal or an alloy.

[0190] The mother liquor extracted in the mother liquor extracting step generally contains the above-mentioned compound. As the mother liquor, a liquid in which the above-mentioned compound is dissolved, an aqueous solution of the above-mentioned compound, or the like can be given. Note that the mother liquor generally contains impurities other than the above-mentioned compound and water.

[0191] Note that the mother liquor extracted in the mother liquor extracting step refers to the mother liquor immediately after passing through the filter in the mother liquor extracting step.

[0192] The mother liquor extracting step can be appropriately performed using a pump or the like.

[0193] <Step of mixing>

[0194] The production method of the present application preferably further includes a step of mixing a part of the circulating liquid containing the dissolved liquid obtained in the dissolving step with the circulating slurry extracted from the hydraulic cleaning column, without returning the part of the circulating liquid to the hydraulic cleaning column.

[0195] In other words, the production method of the present application preferably includes a step of returning a part of the circulating liquid containing the dissolved liquid obtained in the dissolving step to the hydraulic cleaning column, and a step of mixing another part of the circulating liquid with the circulating slurry extracted from the hydraulic cleaning column, without returning the part of the circulating liquid to the hydraulic cleaning column, before the dissolving step.

[0196] In the production method of the present application, the mass ratio of the circulating liquid returned to the hydraulic cleaning column in the returning step to the circulating liquid mixed with the circulating slurry in the mixing step is preferably 1 : 0.01 to 1 : 4.

[0197] The mass ratio is more preferably 1 : 0.1 to 1 : 3, and further preferably 1 : 0.3 to 1 : 2.

[0198] The above-mentioned mass ratio can be obtained, for example, by directly measuring the flow rates of the bypass line and the flow rate of the circulating solution returned to the hydraulic cleaning column using a flow meter or the like, respectively, in a circulating solution containing the dissolving solution obtained by the above-mentioned dissolving step. The flow rate of the bypass line refers to the flow rate of the bypass solution before being mixed with the circulating slurry, and the flow rate of the circulating solution returned to the hydraulic cleaning column refers to the flow rate of the circulating solution before being returned to the hydraulic cleaning column.

[0199] <obtaining a slurry containing crystals>

[0200] The production method of the present application preferably further includes a step of obtaining a slurry containing crystals of the compound from a solution containing the compound.

[0201] The solution containing the compound can be obtained, for example, by collecting a gas of the compound as a reaction product obtained by a chemical converter using an absorption tower, and a crude compound obtained by purifying the collected substance is also included in the solution containing the compound. The solution containing the compound is not limited to a solution obtained by self-synthesis, and can be a solution supplied from elsewhere.

[0202] The solution containing the compound can be subjected to cooling, for example, to obtain a slurry containing crystals of the compound.

[0203] The above-mentioned solution containing the compound contains impurities other than the above-mentioned compound and water.

[0204] In the production method of the present application, the above-mentioned solution containing the compound is preferably an aqueous (meth)acrylic acid solution or a crude (meth)acrylic acid solution.

[0205] The aqueous (meth)acrylic acid solution refers to a solution in which (meth)acrylic acid is dissolved in water. The crude (meth)acrylic acid solution refers to a solution composed of (meth)acrylic acid, and contains impurities such as by-products at the time of production of (meth)acrylic acid.

[0206] Note that, as the above-mentioned impurities, for example, propionic acid, acetic acid, maleic acid, benzoic acid, acrylic acid dimer, and the like, aldehydes such as acrolein, furfural, and glyoxal, and the like, acetone, methyl isobutyl ketone, toluene, protoanemonin, and the like can be exemplified.

[0207] By the production method of the present application, impurities contained in the solution containing the compound can be sufficiently removed.

[0208] <obtaining a solution containing a compound>

[0209] In the production method of the present application, the above-mentioned production method preferably further includes a step of obtaining a solution containing the compound from a raw material.

[0210] As for the process of obtaining a solution containing a compound, there is no particular limitation as long as a solution containing a compound is obtained, but in the case where the above-mentioned compound is a (meth)acrylic acid, for example, it can be appropriately performed by the synthesis process of an acrylic acid, the collection process of an acrylic acid, and the like described in Japanese Patent Application Publication No. 2007-182437 (Patent Literature 1).

[0211] In the production method of the compound of the present application, the above-mentioned raw material is at least one selected from the group consisting of propane, propylene, propenal, isobutylene, methacrolein, acetic acid, lactic acid, isopropyl alcohol, 1,3-propanediol, glycerol, and 3-hydroxypropionic acid, and the above-mentioned solution containing a compound is preferably an aqueous (meth)acrylic acid solution or a crude (meth)acrylic acid solution. In addition, the above-mentioned (meth)acrylic acid and / or raw material can be derived from a raw material capable of being regenerated to generate a bio-based (meth)acrylic acid.

[0212] Note that in the process of obtaining a solution containing a compound, impurities such as by-products are generated. For example, in the case where the above-mentioned compound is a (meth)acrylic acid, water, propionic acid, acetic acid, maleic acid, benzoic acid, an acid such as an acrylic acid dimer, propenal, furfural, formaldehyde, glyoxal, acetone, methyl isobutyl ketone, toluene, protoanemonin, and the like are generated as impurities, but by the use of the purification such as the liquid pressure washing column in the production method of the present application, the separation efficiency of the impurities is excellent, and the product can be efficiently obtained.

[0213] (Purification method of a compound)

[0214] In addition, the present application is also a purification method of a compound, wherein the purification method includes a process of supplying a slurry containing crystals of a compound to a liquid pressure washing column; a process of extracting a circulating slurry containing crystals from the liquid pressure washing column, and dissolving the crystals contained in the extracted circulating slurry; a process of returning a part of a circulating liquid containing a solution obtained in the dissolving process to the liquid pressure washing column; and a process of filtering the slurry containing crystals in the liquid pressure washing column using a filter, and extracting a mother liquor using a tube connected to the filter, wherein the distance from the lower end of the filter to the average height of the bottom surface in the liquid pressure washing column is 1000 mm or more.

[0215] Further, the present application is also a purification method of a compound, wherein the purification method includes: a step of feeding a slurry containing crystals of the compound to a hydraulic washing column; a step of extracting a circulating slurry containing the crystals from the hydraulic washing column, and dissolving the crystals contained in the extracted circulating slurry; a step of returning a part of a circulating liquid containing a solution obtained in the dissolving step to the hydraulic washing column; and a step of filtering the slurry containing the crystals in the hydraulic washing column using a filter, and extracting a mother liquor using a pipe connected to the filter, a space velocity (1 / h) of a crystallization bed in the hydraulic washing column being 1 or more and 20 or less from a lower side than the filter.

[0216] In the purification method of the compound of the present application, a ratio of a weight of the mother liquor to a weight of the crystals in the slurry containing the crystals fed to the hydraulic washing column per unit time is preferably 1 or more and 99 or less.

[0217] Further, the purification method of the present application preferably further includes a step of mixing the circulating slurry extracted from the hydraulic washing column without returning a part of the circulating liquid containing the solution obtained in the dissolving step to the hydraulic washing column.

[0218] In other words, the purification method of the present application preferably includes a step of returning a part of the circulating liquid containing the solution obtained in the dissolving step to the hydraulic washing column, and a step of mixing the circulating slurry extracted from the hydraulic washing column without returning another part of the circulating liquid to the hydraulic washing column before the dissolving step.

[0219] By the purification method of the present application, the slurry containing the crystals can be efficiently purified.

[0220] The preferable modes in the purification method of the present application are the same as those in the production method of the present application described above.

[0221] Examples

[0222] Hereinafter, the present application will be more specifically described by citing examples, but the present application is of course not limited to the following examples, and can be appropriately changed within a range capable of conforming to the gist described above and below, and these are included in the scope of protection of the present application.

[0223] Note that, hereinafter, in the case where not particularly mentioned, "%" represents "mass%", and "part" represents "mass part".

[0224] <Measurement of Space Velocity of Crystallization Bed>

[0225] The traveling speed of the crystallization bed was measured by visual confirmation, and was calculated according to the formula (1).

[0226] (Gas chromatograph / liquid chromatograph measuring equipment)

[0227] The following measuring equipment was used to determine acetic acid and furfural.

[0228] Gas chromatograph: Shimadzu Corporation GC-2014

[0229] Liquid Chromatograph: Shimadzu Corporation LC-20AD HPLC unit

[0230] (Method for obtaining acrylic acid aqueous solution)

[0231] According to the method described in International Publication No. 2010 / 032665, propylene is catalytically oxidized in the gas phase to obtain a gas containing acrylic acid. The obtained gas containing acrylic acid is then treated in an absorption tower to obtain an aqueous solution of acrylic acid.

[0232] (Methods for obtaining the slurry)

[0233] 5L capacity, 0.14m² heat transfer area 2 An aqueous solution of acrylic acid is supplied to the crystallization tank. A refrigerant is supplied to the sleeve of the peripheral wall of the crystallization tank for indirect cooling, thereby scraping off the crystals adhering to the inner surface of the crystallization tank by a scraper inside the crystallization tank to prepare a slurry containing crystals (slurry supply).

[0234] The concentrations of the mother liquor supplied to the slurry are: acrylic acid 94% by mass, acetic acid 1.5% by mass, and furfural 1500 ppm.

[0235] [Examples 1-3, Comparative Examples 1 and 2]

[0236] (Purification device)

[0237] As a purification device, it is used except that the number of filters 2 and mother liquor extraction tubes 3 differs from those of other devices, which are configured to include the following: Figure 1 The purification device shown is the same as the purification device.

[0238] Hydraulic cleaning column 1: Inner diameter 40mm, height 3000mm

[0239] Filter 2: Inner diameter 10mm, length (height) 50mm, number of filters 1, filter section structure: circular holes with a diameter of 250μm.

[0240] The tube 3 connected to filter 2 for extracting mother liquor has an inner diameter of 10 mm and consists of 1 tube.

[0241] Return of circulating fluid to the hydraulic cleaning column 1: The melting equipment 22 is returned from the bottom of the column upwards through the return port 25: a coil heat exchanger.

[0242] Distance from lower end of filter to column bottom surface: 1000 mm

[0243] Space velocity of crystallization bed on lower side than filter: 6 (1 / h)

[0244] The pipeline from extraction port 20 to return port 25 is heated by a water jacket.

[0245] (Operating method of purification device)

[0246] The purification device was operated as follows.

[0247] Under the conditions of slurry concentration (crystal concentration) 10 mass%, slurry temperature 9°C, and crystal supply amount 8.4 kg / h, a slurry (supply slurry) containing acrylic acid crystals was supplied to the prepared hydraulic washing column.

[0248] The outside of the hydraulic washing column was kept at 25°C.

[0249] The crystals were extracted together with the circulating liquid from the extraction port 20 of the hydraulic washing column 1 as a circulating slurry and transferred to a device, i.e., a coil heat exchanger, which was operated at a flow rate of 84 kg / h for melting. The linear velocity of the circulating slurry or the circulating liquid containing the melting liquid in the coil heat exchanger was 0.07 m / s.

[0250] The temperature of the water supplied to the coil heat exchanger was adjusted so that the temperature of the circulating liquid at the outlet of the coil heat exchanger was 18°C, and as a result, the set temperature was 35°C.

[0251] A part of the above-mentioned circulating liquid was extracted as a product from the product extraction pipeline 23 at 5.9 kg / h, and the remaining circulating liquid was returned to the hydraulic washing column.

[0252] (Measurement of impurities)

[0253] The concentrations of acetic acid and furfural as impurities in the product were measured using a high-performance liquid chromatograph and a gas chromatograph. The results are shown in Table 1.

[0254] <Example 1>

[0255] Acrylic acid was obtained as a product by the above-mentioned purification device and operating method thereof. The concentrations of acetic acid and furfural in the product are shown in Table 1.

[0256] <Example 2, Comparative Example 1>

[0257] The distance from the lower end of the filter to the column bottom surface and the space velocity of the crystallization bed on the lower side than the filter were changed as described in Table 1, and otherwise, acrylic acid was obtained as a product in the same manner as in Example 1. The concentrations of acetic acid and furfural in the product are shown in Table 1.

[0258] <Example 3, Comparative Example 2>

[0259] The distance from the lower end of the filter to the bottom surface of the column and the space velocity of the crystalline bed on the lower side of the filter were changed as described in Table 1, and the slurry of the crystals containing acrylic acid supplied to the hydraulic washing column was set to a crystal concentration of 25%, and otherwise, in the same manner as in Example 1, acrylic acid was obtained as a product. The concentrations of acetic acid and furfural in the product are shown in Table 1.

[0260] [Table 1]

[0261]

[0262] As is clear from the results of Examples 1 to 3 and Comparative Examples 1 and 2 according to the above Table 1, the method for producing a compound includes the steps of supplying a slurry of crystals containing a compound to a hydraulic washing column, extracting a circulating slurry containing crystals from the hydraulic washing column, dissolving the crystals contained in the extracted circulating slurry, returning a part of a circulating liquid containing a solution obtained in the dissolving step to the hydraulic washing column, and filtering the slurry containing crystals in the hydraulic washing column using a filter, and extracting a mother liquor using a pipe connected to the filter, and the distance from the lower end of the filter to the average height of the bottom surface in the hydraulic washing column is 1000 mm or more, whereby the separation efficiency of impurities is excellent, and the product can be efficiently obtained.

[0263] By the distance from the lower end of the filter to the average height of the bottom surface in the hydraulic washing column being 1000 mm or more, the space velocity of the crystalline bed on the lower side of the filter in the hydraulic washing column is moderately suppressed, in other words, the residence time of the crystalline bed on the lower side of the filter is sufficiently long, and it is considered that the separation efficiency of impurities is excellent.

[0264] Thus, even if the scale of the purification device of the present application is enlarged, as long as the distance from the lower end of the filter to the average height of the bottom surface in the hydraulic washing column is 1000 mm or more, the effect of being able to obtain a high-quality product of the present application can be exerted.

[0265] <Example 4>

[0266] The amount of crystals supplied to the hydraulic washing column was changed to 4.2 kg / h, the product extraction flow rate was changed to 2.9 kg / h, and the distance from the lower end of the filter to the bottom surface of the column was changed to 500 mm, and otherwise, in the same manner as in Example 1, acrylic acid was obtained as a product. The concentrations of acetic acid and furfural in the product are shown in Table 1.

[0267] As is clear from the results of Example 4, even if the distance from the lower end of the filter to the average height of the bottom surface of the hydraulic washing column is less than 1000 mm, by moderately adjusting the space velocity of the crystalline bed on the lower side than the filter in the hydraulic washing column, the separation efficiency of impurities is excellent, and the product can be efficiently obtained.

[0268] <Example 5>

[0269] In the purification device used in Example 1, in addition to the bypass line connecting the extraction line and the return line, the operation was performed under the same conditions as in Example 1. That is, except that the number of filters 102 and mother liquor extraction lines 103 was different from the device configured to include the following, no valve V was provided in the bypass line, and the same purification device as shown in Figure 2 the purification device was used, and the operation was performed under the same conditions as in Example 1.

[0270] Hydraulic washing column 101: inner diameter 40 mm, height 3000 mm

[0271] Filter 102: inner diameter 10 mm, length (height) 50 mm, number 1, filter portion configuration: circular hole of 250 μm diameter

[0272] Line 103 connected to the filter 102 for extracting the mother liquor: inner diameter 10 mm, number 1

[0273] Distance 131 from the lower end of the filter to the bottom surface of the column: 1000 mm

[0274] Space velocity of the crystalline bed on the lower side than the filter: 6 (1 / h)

[0275] The flow rate of the bypass line 126, the flow rate of the circulating slurry or circulating liquid containing the dissolved liquid flowing in the coil heat exchanger, and the linear velocity were operated under the following conditions.

[0276] • Flow rate of the bypass line 126: 84 kg / h

[0277] • Flow rate of the circulating slurry or circulating liquid containing the dissolved liquid flowing in the coil heat exchanger: 168 kg / h

[0278] • Linear velocity of the circulating slurry or circulating liquid containing the dissolved liquid flowing in the coil heat exchanger: 0.14 m / s

[0279] As in Example 1, the temperature of the water supplied to the coil heat exchanger was adjusted so that the temperature of the circulating liquid at the outlet of the coil heat exchanger was 18°C, and as a result, the set temperature was 32°C.

[0280] As can be seen, by providing the bypass line 126, the heat exchange efficiency of the coil heat exchanger is improved, and the crystals in the circulating slurry can be dissolved at a lower set temperature.

[0281] As can be seen, in terms of handling (meth)acrylic acid, which is a polymerizable substance, since the set temperature of the dissolving device can be lowered, polymerization can be more suppressed, stable operation can be performed, and furthermore, products can be manufactured more efficiently. In addition, the concentrations of acetic acid and furfural in the acrylic acid obtained as products were equivalent to those of Example 1.

[0282] Reference signs explanation

[0283] 1, 101 hydraulic cleaning column

[0284] 2, 102 filter for filtering the slurry containing crystals in the hydraulic cleaning column

[0285] 3, 103 pipe for extracting mother liquor connected to the filter

[0286] 4, 104 pipe for supplying the slurry containing crystals to the hydraulic cleaning column

[0287] 11, 111 supply line (for supplying the slurry containing crystals to the hydraulic cleaning column)

[0288] 11a, 111a slurry containing crystals

[0289] 12, 112 mother liquor

[0290] 20, 120 extraction port of the circulating slurry

[0291] 21, 121 extraction line connecting the extraction port of the circulating slurry and the dissolving device

[0292] 22, 122 dissolving device

[0293] 23, 123 product extraction line (connected to the product extraction port)

[0294] 23a, 123a product (after purification)

[0295] 24, 124 return line (connecting the dissolving device and the above-mentioned return port)

[0296] 121a portion connecting the extraction port of the circulating slurry and the extraction line to the confluence point of the bypass line

[0297] 121b portion connecting the confluence point of the extraction line and the bypass line to the dissolving device

[0298] 124a Part connecting the device for melting to the branch point where the bypass line branches from the return line

[0299] 124b Part connecting the branch point where the bypass line branches from the return line to the return port

[0300] 25, 125 Return port (circulating liquid of the melted solution containing extracted crystals)

[0301] 31, 131 Distance from the lower end of the filter to the bottom surface of the column

[0302] 126 Bypass line

[0303] P Pump

[0304] V Valve

Claims

1. A purification device, characterized in that, A purification device for purifying crystals, The purification device is configured by including: a hydraulic cleaning column provided with an extraction port of circulating slurry containing crystals and a return port of circulating liquid containing a dissolved liquid of the extracted crystals; a pipe that supplies the slurry containing the crystals to the hydraulic cleaning column; a filter that filters the slurry containing the crystals in the hydraulic cleaning column; a pipe that is connected to the filter and extracts a mother liquor; and a device that dissolves the crystals contained in the circulating slurry extracted from the extraction port, the distance from the lower end of the filter to the average height of the bottom surface in the hydraulic cleaning column is 1000 mm or more and 10000 mm or less.

2. The purification device of claim 1, wherein, The purification device further includes: an extraction line that connects the extraction port to the device that dissolves; a return line that connects the device that dissolves to the return port; and a bypass line that connects the extraction line to the return line.

3. A production method of a compound, characterized by The production method includes: a step of supplying a slurry containing crystals of the compound to a hydraulic cleaning column; a step of extracting a circulating slurry containing the crystals from the hydraulic cleaning column, and dissolving the crystals contained in the extracted circulating slurry; a step of returning a part of a circulating liquid containing a dissolved liquid obtained in the dissolving step to the hydraulic cleaning column; and a step of filtering the slurry containing the crystals in the hydraulic cleaning column using a filter, and extracting a mother liquor using a pipe connected to the filter, the distance from the lower end of the filter to the average height of the bottom surface in the hydraulic cleaning column is 1000 mm or more, the space velocity (1 / h) of a crystallization bed on the lower side than the filter in the hydraulic cleaning column is 6 or less, the ratio of the weight of the mother liquor to the weight of the crystals in the slurry containing the crystals supplied to the hydraulic cleaning column per unit time is 4 or more and 19 or less.

4. A production method of a compound, characterized by The production method includes: a step of supplying a slurry containing crystals of the compound to a hydraulic cleaning column; a step of extracting a circulating slurry containing the crystals from the hydraulic cleaning column, and dissolving the crystals contained in the extracted circulating slurry; a step of returning a part of a circulating liquid containing a dissolved liquid obtained in the dissolving step to the hydraulic cleaning column; and a step of filtering the slurry containing the crystals in the hydraulic cleaning column using a filter, and extracting a mother liquor using a pipe connected to the filter, the space velocity (1 / h) of a crystallization bed on the lower side than the filter in the hydraulic cleaning column is 1 or more and 6 or less, the ratio of the weight of the mother liquor to the weight of the crystals in the slurry containing the crystals supplied to the hydraulic cleaning column per unit time is 4 or more and 19 or less.

5. The method of manufacturing a compound according to claim 3 or 4, wherein The production method further includes a step of not returning a part of a circulating liquid containing a dissolved liquid obtained in the dissolving step to the hydraulic cleaning column, but mixing with a circulating slurry extracted from the hydraulic cleaning column.

6. The method of claim 3 or 4, wherein the compound is prepared by the process of claim 5. The production method further includes a step of obtaining a slurry containing crystals of the compound from a solution containing the compound.

7. The method for manufacturing the compound according to claim 5, characterized in that, The production method further includes a step of obtaining a slurry containing crystals of the compound from a solution containing the compound.

8. The method for manufacturing the compound according to claim 6, characterized in that, The solution containing the compound is an aqueous (meth)acrylic acid solution or a crude (meth)acrylic acid solution.

9. The method of producing a compound according to any one of claims 3, 4, and 7, wherein The method of producing a compound further includes a step of obtaining a solution containing the compound from a raw material.

10. The method of producing a compound according to claim 5, wherein The method of producing a compound further includes a step of obtaining a solution containing the compound from a raw material.

11. The method of producing a compound according to claim 6, wherein The method of producing a compound further includes a step of obtaining a solution containing the compound from a raw material.

12. The method of producing a compound according to claim 9, wherein The raw material is at least one selected from the group consisting of propane, propylene, propenal, isobutylene, methacrolein, acetic acid, lactic acid, isopropanol, 1,3-propanediol, glycerol, and 3-hydroxypropionic acid, The solution containing the compound is an aqueous (meth)acrylic acid solution or a crude (meth)acrylic acid solution.

13. A method of purifying a compound, comprising: a step of feeding a slurry containing crystals of the compound to a hydraulic washing column; a step of extracting a circulating slurry containing the crystals from the hydraulic washing column, and dissolving the crystals contained in the extracted circulating slurry; a step of returning a part of a circulating liquid containing a solution obtained in the dissolving step to the hydraulic washing column; and a step of filtering the slurry containing the crystals in the hydraulic washing column using a filter, and extracting a mother liquor using a pipe connected to the filter, a distance from a lower end of the filter to an average height of a bottom surface in the hydraulic washing column is 1000 mm or more, a space velocity (1 / h) of a crystallization bed on a lower side than the filter in the hydraulic washing column is 6 or less, a ratio of a weight of the mother liquor to a weight of the crystals in the slurry containing the crystals fed to the hydraulic washing column per unit time is 4 or more and 19 or less.

14. A method of purifying a compound, comprising: a step of feeding a slurry containing crystals of the compound to a hydraulic washing column; a step of extracting a circulating slurry containing the crystals from the hydraulic washing column, and dissolving the crystals contained in the extracted circulating slurry; a step of returning a part of a circulating liquid containing a solution obtained in the dissolving step to the hydraulic washing column; and a step of filtering the slurry containing the crystals in the hydraulic washing column using a filter, and extracting a mother liquor using a pipe connected to the filter, a space velocity (1 / h) of a crystallization bed on a lower side than the filter in the hydraulic washing column is 1 or more and 6 or less, a ratio of a weight of the mother liquor to a weight of the crystals in the slurry containing the crystals fed to the hydraulic washing column per unit time is 4 or more and 19 or less. The method of purifying a compound includes a step of mixing the circulating slurry extracted from the hydraulic washing column, instead of returning a part of the circulating liquid containing the solution obtained in the dissolving step to the hydraulic washing column. ​ 15. The method of purifying a compound according to claim 13 or 14, wherein, ​

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