Process and apparatus for removing water from a crude composition containing water, phenol and bisphenol a
Patent Information
- Application Number
- CN202580020952.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-03-11
- Filing Date
- 2025-03-10
- Publication Date
- 2026-10-27
Smart Images
Figure CN122995884A_ABST
Abstract
Description
[0001] This invention relates to a method and apparatus for removing water from a crude composition containing water, phenol and bisphenol A.
[0002] Bisphenol A (BPA) is an important raw material in industrial processes, particularly as a key comonomer in the production of various polymers such as polycarbonates, epoxy resins, polysulfones, polycyanates, and polyetherimides. BPA is typically synthesized by condensing acetone and phenol to produce BPA and water, resulting in a reaction mixture or crude composition containing synthesized BPA, water (a byproduct), unreacted acetone, unreacted phenol, and the byproduct. The crude composition is then purified to reduce the contents of water, acetone, and phenol to sufficiently low levels so that the purified BPA can be used in desired applications, such as as a comonomer in the production of epoxy resins.
[0003] Typically, the crude composition containing bisphenol A is processed in two subsequent distillation steps, with the second distillation step using an entrainer (e.g., ethylbenzene) as an azeotropic distillation to break up the water-phenol azeotrope. More specifically, in the first upstream distillation step, fairly pure bisphenol A is separated from the crude composition as the bottom composition, while the top composition contains water, acetone, phenol, and byproducts. The water is then separated from the phenol and acetone in the second downstream azeotropic distillation. However, this process is very energy-intensive because the significant amount of water contained in the crude composition must be heated twice. More specifically, the crude composition, primarily containing water and bisphenol A, and smaller amounts of unreacted acetone and phenol, is first heated in the first distillation column to separate the bisphenol A from the crude composition. The aqueous top composition is then condensed, partially recycled back to the first distillation column as reflux, while the remainder of the condensed top composition is introduced into the downstream azeotropic distillation column, where the top composition containing a significant amount of water is heated / evaporated a second time.
[0004] In view of this, the object upon which the present invention is based is to provide a method and apparatus for removing water from a crude composition containing water, phenol and bisphenol A, and particularly also containing acetone, to obtain dehydrated bisphenol A, but characterized by low energy consumption.
[0005] According to the present invention, this objective is achieved by providing a method for removing water from a crude composition containing water, phenol, and bisphenol A, wherein the method comprises the following steps: a) The crude composition is fed into a dividing-wall distillation column and distilled therein to obtain a top composition, a side composition, and a bottom composition, wherein the bottom composition is a dehydrated bisphenol A composition. b) The top composition obtained in step a) is subjected to liquid-liquid extraction with an extractant in an extraction column to obtain a water-rich raffinate composition and a phenol-rich extract composition, and c) The extract composition obtained in step b), the side stream composition obtained in step a), and the same extractant used in step b) are fed separately into a distillation column and distilled therein to obtain a top composition containing extractant and water and a bottom composition containing phenol.
[0006] This technical solution is based on the following discovery: by first separating a crude composition containing bisphenol A in a separatory wall column into a top composition mainly composed of water and small amounts of phenol and acetone, a side-stream composition mainly composed of phenol and small amounts of water and acetone, and a dehydrated bisphenol A composition, wherein only the side-stream composition with a relatively low water content is directly fed into a downstream distillation column used as an extractant recovery distillation column, while the top composition mainly composed of water and small amounts of phenol and acetone is subjected to liquid-liquid extraction, so that most of the water contained in the top composition of the separatory wall distillation column is separated as the raffinate composition from the extractant composition with a relatively low water content and a relatively high phenol content, wherein only the extractant composition with a relatively low water content is introduced into the extractant recovery distillation column, then only a relatively small portion of the water contained in the crude composition needs to be heated twice. That is, only a small portion of the water contained in the sidestream composition obtained in the partitioned wall distillation column and the water contained in the extract composition obtained in the liquid-liquid extraction step are introduced into the extractant recovery distillation column and must be heated / evaporated therein, while the majority of the water separated as the raffinate composition in the liquid-liquid extraction step is not introduced into the extractant recovery distillation step at all, thus eliminating the need for two heating / evaporation cycles. Furthermore, since most of the phenol contained in the crude composition is separated from the water in the crude composition as a sidestream composition and directly introduced into the extractant recovery distillation without liquid-liquid extraction, liquid-liquid extraction is only performed on a relatively small volume of the crude composition, thus requiring only a relatively low amount of extractant. Another advantage of the method according to the invention is that the same extractant is used in steps b) and c). Thus, the management of two different streams (i.e., the first extractant stream and a different second extractant stream) can be simplified to the management of only one stream. In summary, the combined implementation of a partitioned distillation column and an extraction column can yield dehydrated bisphenol A compositions, and compared with existing methods (where the crude composition is separated into a top composition and a pure bisphenol A composition as a bottom composition in a conventional distillation column without a partitioned wall, and then all the top compositions are introduced into azeotropic distillation), this method reduces the energy consumption of the process by at least 30%.
[0007] The present invention does not impose any particular limitation on the type and content of impurities in the crude composition containing bisphenol A. The method according to the invention has proven particularly suitable for dehydrating such crude compositions, based on 100% by weight containing 15 to 35% by weight bisphenol A, 1 to 5% by weight water, 0.5 to 5% by weight acetone, and 60 to 80% by weight phenol. More preferably, the crude composition, based on 100% by weight, contains 20 to 30% by weight bisphenol A, 1.5 to 2.0% by weight water, 0.8 to 2.9% by weight acetone, and 65 to 75% by weight phenol.
[0008] The present invention does not particularly limit the type of distillation column used in step a). Therefore, any distillation column comprising a partition wall that divides at least one longitudinal extension of the partition wall into two sub-segments in its cross-section can be used. Preferably, the partition wall is arranged at least substantially vertically downward in the partition wall distillation column. According to the invention, at least substantially vertically downward means that the angle between the partition wall and the longitudinal axis of the partition wall distillation column or with the vertical direction is at most 20°, preferably at most 10°, more preferably at most 5°, and most preferably 0°.
[0009] According to a particularly preferred embodiment of the invention, in step a), the crude composition is fed into an intermediate partition wall distillation column. According to the invention, an intermediate partition wall distillation column is defined as a partition wall distillation column comprising a partition wall extending at least substantially vertically downward from a point located below the top of the distillation column to a point located above the bottom of the partition wall distillation column, thereby subdividing the partition wall distillation column into a top section above the partition wall, a bottom section below the partition wall, and an intermediate section, the intermediate section comprising a first intermediate sub-section located on one side of the partition wall and a second intermediate sub-section located on the opposite side of the partition wall. Good results are obtained particularly when the partition wall extends from a point located at 10 to 45% of the distance from the bottom to the top of the partition wall distillation column, to a point located at 50 to 90% of the distance from the bottom to the top of the partition wall distillation column, preferably from a point located at 25 to 40% of the distance from the bottom to the top of the partition wall distillation column, to a point located at 60 to 80% of the distance from the bottom to the top of the partition wall distillation column, viewed from bottom to top. Furthermore, preferably, when viewed from the bottom up of the partition wall distillation column, the partition wall extends beyond 5 to 90% of the distance from the bottom to the top of the partition wall distillation column, more preferably 20 to 80%, and most preferably 30 to 70%.
[0010] In a further development of the inventive concept, it is proposed that, viewed from the cross-section of the partitioned-wall distillation column, the partition wall subdivides the middle section of the column into approximately two equal-sized sub-sections or halves. Therefore, preferably, one of the first and second intermediate sub-sections covers at least 30%, more preferably at least 40%, even more preferably at least 45%, and most preferably 50% of the total cross-sectional area of the middle section of the partitioned-wall column, while the other of the first and second intermediate sub-sections covers the remainder to 100% of the total cross-sectional area of the middle section of the partitioned-wall column. For example, one sub-section covers 43% of the total cross-sectional area, and the other covers 57%, or each of the two sub-sections covers exactly 50% of the total cross-sectional area. If the total cross-sectional area of the middle section varies along the axial length of the middle section, the above values are related to the average total cross-sectional area of the middle section.
[0011] Preferably, the distillation in step a) is carried out at a temperature of 0 to 200°C and a pressure of 10 to 150 MPa, more preferably at a temperature of 80 to 160°C and a pressure of 10 to 80 MPa.
[0012] According to another preferred embodiment of the invention, the dehydrated bisphenol A composition obtained as the bottom composition in the separator distillation column in step a) contains, based on 100% by weight, at least 15% by weight, preferably at least 20% by weight, more preferably at least 30% by weight (e.g., 20 to 40% by weight) of bisphenol A, and at most 80% by weight (e.g., 60 to 80% by weight) or at most 70% by weight of phenol. The dehydrated bisphenol A composition, based on 100% by weight, may contain trace impurities, such as at most 0.1% by weight of water and at most 0.1% by weight (e.g., 7 to 100 ppm) of acetone. The content of these impurities can be further reduced by removing phenol from the dehydrated bisphenol A composition through further purification steps (e.g., evaporation and / or crystallization).
[0013] Conversely, the top composition preferably contains 30 to 80% by weight of water, 10 to 50% by weight of acetone and 0 to 20% by weight of phenol, based on 100% by weight of the top composition.
[0014] The overhead composition obtained in the partitioned wall distillation column can be directly introduced into the extraction column used in step b). However, preferably, as with conventional distillation, the overhead composition taken from the partitioned wall distillation column used in step a) is first condensed in a condenser into a condensed overhead composition, a portion of which is refluxed back to the upper section of the partitioned wall distillation column, while the remainder of the condensed overhead composition is introduced into the extraction column.
[0015] In a further development of the inventive concept, it is proposed that the extractant used in steps b) and c) be selected from the group consisting of methyl isobutyl ketone, diisopropyl ether, ethylbenzene, toluene, hexane, octane, benzene, heptane, cyclohexane, hexadecane, and any combination of two or more of the above compounds. In particular, good results are obtained when ethylbenzene and / or methyl isobutyl ketone are used as extractants in steps b) and c), with ethylbenzene being the most preferred.
[0016] The present invention does not particularly limit the type of liquid-liquid extraction performed in step b), i.e., the type of liquid-liquid extraction tower used in step b). However, it is preferable to perform the liquid-liquid extraction in step b) in a stirred extraction tower. Particularly good results are obtained when the liquid-liquid extraction in step b) is performed in a stirred countercurrent extraction tower. Performing the liquid-liquid extraction in step b) in a stirred extraction tower results in increased liquid-liquid extraction efficiency, thereby enabling the minimization of the amount of extractant required for liquid-liquid extraction.
[0017] The stirred liquid-liquid extraction column preferably includes at least one, more preferably multiple (e.g., 2 to 80, more preferably 5 to 40) stirring elements disposed within the liquid-liquid extraction column. For example, each stirring element includes one or more rotating shafts, each shaft connected to one or more agitators, preferably selected from the group consisting of discs, blades, impellers, turbine impellers, fins, and any combination of two or more of the above agitators. Furthermore, the stirred liquid-liquid extraction column includes an inlet line for the extractant, an inlet line for the top composition obtained in the partition wall distillation column of step a), an outlet line for the extractant, and an outlet line for the raffinate. Preferably, the inlet line for the extractant and the inlet line for the top composition obtained in the partition wall distillation column of step a) are arranged at opposite ends of the liquid-liquid extraction column. Similarly, the outlet line for the extract and the outlet line for the raffinate are preferably arranged at opposite ends of the liquid-liquid extraction tower. Preferably, the outlet line for the extract and the inlet line for the top composition obtained in the partition wall distillation tower in step a) are arranged at the same end of the liquid-liquid extraction tower, while the outlet line for the raffinate and the inlet line for the extractant are arranged at opposite ends of the liquid-liquid extraction tower.
[0018] In particular, good results can be obtained when the stirred liquid-liquid extraction column comprises two or more compartments separated from each other by static baffles, wherein at least some, and preferably all, of the compartments contain a rotating shaft with one or more agitators, which are preferably selected from the group consisting of: discs, blades, impellers, turbine impellers, fins, and any combination of two or more of the above agitators. For example, the stirred liquid-liquid extraction column in which stirred liquid-liquid extraction is performed can be implemented as a Kühni column, etc.
[0019] Preferably, the liquid-liquid extraction during step b) is carried out in a liquid-liquid extraction tower at ambient temperature and atmospheric pressure.
[0020] For example, the raffinate composition obtained in step b) may contain 90 to 99.99% by weight, preferably 95 to 99.99% by weight, of water based on 100% by weight of the raffinate composition, wherein the balance of the raffinate composition up to 100% by weight is extractant and impurities, such as 0 to 1% by weight of phenol and 0 to 0.1% by weight of acetone.
[0021] In a further development of the inventive concept, it is proposed that the extract composition obtained in step b) contains 0.5 to 25% by weight, preferably 1 to 10% by weight, phenol, based on 100% by weight of the extract composition. The balance of the extract composition up to 100% by weight is extractant and impurities, such as 0 to 10% by weight of water and 0 to 10% by weight of acetone.
[0022] According to the invention, the extractant used in step c) is the same as the extractant used in step b), because this simplifies the management of two different streams (i.e., the first extractant and a different second extractant) to the management of only one stream. Most preferably, the extractant used in step c)—as in step b)—is ethylbenzene.
[0023] According to another preferred embodiment of the invention, in step c), the extractant is fed into the distillation column at a position above the position where the extract composition obtained in step b) is fed into the distillation column, wherein the position where the extract composition obtained in step b) is fed into the distillation column is above the position where the side-line composition obtained in step a) is fed into the distillation column.
[0024] Preferably, in step c), the extractant is fed into the distillation column at a position 0 to 50%, preferably 1 to 30%, and most preferably 5 to 20%, below the top of the distillation column and at a distance from the top to the bottom of the distillation column. Furthermore, it is preferable to feed the extract composition into the distillation column below the position where the extractant is fed into the distillation column, and below the top of the distillation column, at a position 20 to 80%, preferably 30 to 70%, and most preferably 40 to 65%, of the distance from the top to the bottom of the distillation column. Conversely, it is preferable to feed the sidestream composition into the distillation column below the position where the extract composition is fed into the distillation column, and preferably below the top of the partition wall distillation column, at a position 60 to 100%, preferably 70 to 99%, and most preferably 75 to 95%, of the distance from the top to the bottom of the partition wall distillation column.
[0025] Preferably, the distillation in step c) is carried out at a temperature of 70 to 250°C and a pressure of 0.02 to 0.50 MPa, more preferably at a temperature of 100 to 210°C and a pressure of 0.05 to 0.20 MPa.
[0026] In a further development of the inventive concept, it is proposed that the overhead composition obtained in the distillation column contains 85 to 100% by weight of extractant and 0 to 15% by weight of water, as well as a small amount of impurities, such as up to 0.5% by weight of acetone, based on 100% by weight of the overhead composition.
[0027] According to another particularly preferred embodiment of the invention, the extractant is recovered from the overhead composition obtained from the distillation column used in step c) before the extractant is recycled back to the liquid-liquid extraction step b) and the distillation step c). More specifically, for this purpose, it is preferable to introduce the overhead composition obtained in step c) into a liquid-liquid separator, in which, if necessary, the overhead composition is separated into a first liquid composition and a second liquid composition after condensation, wherein the first liquid composition is rich in extractant and has a lower density than the second liquid composition rich in water, and wherein the first liquid composition is fed at least partially as extractant to the distillation column used in step c). The overhead composition obtained from the distillation column can be introduced directly into the liquid-liquid separator. However, preferably, as in conventional distillation, the overhead composition taken from the distillation column used in step c) is first condensed in a condenser into a condensed overhead composition, and then the condensed overhead composition is introduced into a liquid-liquid separator, which preferably includes an outlet line for a first liquid composition and an outlet line for a second liquid composition, wherein the outlet line for the first liquid composition is divided into two lines, such that a portion of the first liquid composition is refluxed back to the upper section of the distillation column, while the remaining portion of the first liquid composition is preferably refluxed back to the liquid-liquid extraction column.
[0028] The present invention does not particularly limit the type of liquid-liquid separator. Preferably, the liquid-liquid separator is a settling tank in which the first and second liquid compositions are separated from each other by gravity. Suitable examples of such settling tanks are horizontal vessels comprising one or more separation walls arranged at least substantially vertically, wherein, according to the invention, at least substantially vertical arrangement means that the angle between the separation wall and the vertical direction is at most 20°, preferably at most 10°, more preferably at most 5°, and most preferably 0°. Good results are particularly obtained when the one or more separation walls extend from the bottom of the horizontal vessel beyond 50 to 95%, preferably 60 to 90%, of the height of the horizontal vessel. More preferably, the horizontal vessel comprises one such separation wall. Thus, the denser second liquid composition settles below the first liquid composition in the first section of the horizontal container located upstream of the separation wall, allowing only the first liquid composition to flow across the upper edge of the separation wall into the second section of the horizontal container located downstream of the separation wall, while the second liquid composition remains in and is removed from the first section of the horizontal container, and the first liquid composition is removed from the second section of the horizontal container.
[0029] In a further development of the inventive concept, it is proposed to feed a portion of the first liquid composition obtained in the above-described liquid-liquid separator as an extractant into the distillation column used in step c), and to feed another portion of the first liquid composition as an extractant into the liquid-liquid extraction column used in step b). In particular, good results can be obtained when 10 to 90% by weight, more preferably 15 to 45% by weight, of the first liquid composition is fed as an extractant into the distillation column used in step c), while the remainder of the first liquid composition is fed as an extractant up to 100% by weight into the liquid-liquid extraction column used in step b).
[0030] Preferably, the bottom composition obtained in the distillation column used in step c) contains 90 to 100% by weight, preferably 98 to 99.99% by weight, of phenol based on 100% by weight of the bottom composition.
[0031] To reduce the acetone content in a single process composition, a further development of the inventive concept proposes that the method further include a stripping step for removing acetone from the composition, wherein the stripping step is performed on one or more of the following compositions: i) Before introducing the remaining composition (from which acetone has been at least partially vaporized) into the liquid-liquid extraction column of step b), the overhead composition obtained in step a), preferably a portion of the overhead composition obtained in step a) that has been condensed in a condenser and from which a portion of the condensed overhead composition has been removed and recycled back to the remaining condensed overhead composition after the partition wall distillation column, ii) The raffinate composition obtained in step b), iii) The extract composition obtained in step b) before introducing the remaining composition (from which acetone has been at least partially vaporized) into the distillation column of step c), iv) The overhead composition obtained in step c), preferably the overhead composition obtained in step c) has been condensed in the condenser and a portion of the condensed overhead composition has been removed and recycled back to the remaining condensed overhead composition after distillation, and v) The crude composition before being fed into the partition wall distillation column of step a).
[0032] Stripping can be a step of contacting any of the above compositions i) to v) preferably in a countercurrent direction with a gas (e.g., nitrogen, air, or steam) to desorb acetone from the respective composition into the gas. Other stripping methods employed in the prior art can also be used.
[0033] According to another aspect, the present invention relates to an apparatus for removing water from a crude composition containing water, phenol, and bisphenol A, wherein the apparatus comprises: a) A partitioned-wall distillation column comprising an inlet line for a crude composition, an outlet line for a top composition, an outlet line for a side-stream composition, and an outlet line for a bottom composition. b) A liquid-liquid extraction column, comprising an inlet line directly or indirectly connected to the outlet line of a partitioned wall distillation column for the top composition, an inlet line for the extractant, an outlet line for the extractant, and an outlet line for the raffinate, and c) A distillation column comprising an inlet line directly or indirectly connected to the outlet line of a liquid-liquid extraction column for the extractant, an inlet line connected to the outlet line of a partition wall distillation column for the side-stream composition, an inlet line for the extractant, an outlet line for the top composition, and an outlet line for the bottom composition.
[0034] According to a particularly preferred embodiment of the invention, the apparatus further comprises a liquid-liquid separator, which includes an inlet line, a first outlet line, and a second outlet line. The inlet line of the liquid-liquid separator is directly or indirectly connected to the outlet line of the distillation column for the top composition, and the first outlet line of the liquid-liquid separator is connected to the inlet line of the liquid-liquid extraction column for the extractant and to the inlet line of the distillation column for the extractant. The second outlet line of the liquid-liquid separator is used to discharge water from the apparatus. Preferably, the inlet line of the liquid-liquid separator is indirectly connected to the outlet line of the distillation column for the top composition, i.e., a condenser is located between the outlet line of the distillation column for the top composition and the inlet line of the liquid-liquid separator, wherein the condenser includes an outlet line leading to the inlet line of the liquid-liquid separator.
[0035] The present invention does not particularly limit the type of liquid-liquid separator. Preferably, the liquid-liquid separator is a settling tank in which the first and second liquid compositions are separated from each other by gravity. A suitable example of such a settling tank is a horizontal container comprising one or more separation walls arranged at least substantially vertically, wherein, according to the invention, at least substantially vertically arranged means that the angle between the separation wall and the vertical direction is at most 20°, preferably at most 10°, more preferably at most 5°, and most preferably 0°. Good results are particularly obtained when the one or more separation walls extend from the bottom of the horizontal container beyond 50 to 95%, preferably 60 to 90%, of the height of the horizontal container. More preferably, the horizontal container comprises one such separation wall. Thus, the denser second liquid composition settles below the first liquid composition in the first section of the horizontal container located upstream of the separation wall, such that only the first liquid composition can flow across the upper edge of the separation wall into the second section of the horizontal container located downstream of the separation wall, while the second liquid composition remains in and is removed from the first section of the horizontal container, and the first liquid composition is removed from the second section of the horizontal container.
[0036] In particular, good results are obtained when the partition wall distillation column is an intermediate partition wall distillation column, which comprises a partition wall extending at least substantially vertically downward from a point located below the top of the distillation column to a point located above the bottom of the partition wall distillation column. Thus, the partition wall distillation column is subdivided into a top section above the partition wall, a bottom section below the partition wall, and an intermediate section, the intermediate section comprising a first intermediate sub-section located on one side of the partition wall and a second intermediate sub-section located on the opposite side of the partition wall.
[0037] In particular, good results can be obtained when the dividing wall extends from a point located at 10 to 45% of the distance from the bottom to the top of the dividing wall distillation column, to a point located at 50 to 90% of the distance from the bottom to the top of the dividing wall distillation column, preferably from a point located at 25 to 40% of the distance from the bottom to the top of the dividing wall distillation column, to a point located at 60 to 80% of the distance from the bottom to the top of the dividing wall distillation column.
[0038] In a further development of the inventive concept, it is proposed that, viewed from the bottom up of the partition wall distillation column, the partition wall extends beyond 5 to 90%, preferably 20 to 80%, and more preferably 30 to 70% of the distance from the bottom to the top of the partition wall distillation column.
[0039] Preferably, one of the first and second intermediate sub-regions covers at least 30%, more preferably at least 40%, even more preferably at least 45%, and most preferably 50% of the total cross-sectional area of the intermediate section of the intermediate partition wall tower, while the other of the first and second intermediate sub-regions covers the remainder of 100% of the total cross-sectional area of the intermediate section of the partition wall tower.
[0040] According to another preferred embodiment of the invention, the liquid-liquid extraction tower is a stirred extraction tower, preferably a stirred countercurrent extraction tower. Good results are particularly obtained when the stirred extraction tower includes at least one, preferably multiple (e.g., 2 to 80, more preferably 5 to 40) stirring elements disposed within the liquid-liquid extraction tower. For example, each stirring element includes one or more rotating shafts, each shaft connected to one or more agitators, preferably selected from the group consisting of discs, blades, impellers, turbine impellers, fins, and any combination of two or more of the above agitators. Furthermore, the stirred extraction tower preferably includes an inlet line for the extractant, an inlet line for the top composition obtained in the partition wall distillation column of step a), an outlet line for the extractant, and an outlet line for the raffinate. Preferably, the inlet line for the extractant and the inlet line for the top composition obtained in the partition wall distillation column of step a) are arranged at opposite ends of the liquid-liquid extraction tower. Similarly, the outlet line for the extract and the outlet line for the raffinate are preferably arranged at opposite ends of the liquid-liquid extraction tower. Preferably, the outlet line for the extract and the inlet line for the top composition obtained in the partition wall distillation tower in step a) are arranged at the same end of the liquid-liquid extraction tower, while the outlet line for the raffinate and the inlet line for the extractant are arranged at opposite ends of the liquid-liquid extraction tower.
[0041] In particular, good results can be obtained when the stirred extraction column comprises two or more compartments separated from each other by static baffles, wherein at least some, and preferably all, of the compartments contain a rotating shaft with one or more agitators, which are preferably selected from the group consisting of: discs, blades, impellers, turbine impellers, fins, and any combination of two or more of the above agitators. For example, a liquid-liquid extraction column in which stirred liquid-liquid extraction is performed can be implemented as a Kühni column, etc.
[0042] Preferably, the inlet line of the liquid-liquid extraction column is indirectly connected to the outlet line of the partition wall distillation column for the top composition, i.e., the condenser is located between the outlet line of the partition wall distillation column for the top composition and the inlet line of the liquid-liquid extraction column, wherein the condenser includes an outlet line, which is divided into a circulation line leading to the partition wall distillation column and an inlet line leading to the liquid-liquid extraction column.
[0043] According to another particularly preferred embodiment of the invention, the apparatus further comprises at least one stripping tower for removing acetone, wherein the at least one stripping tower is arranged in any of the following locations: i) In the pipeline connecting the outlet line of the partition wall distillation column for the top composition and the inlet line of the liquid-liquid extraction column, preferably downstream of a condenser in the pipeline connecting the outlet line of the partition wall distillation column for the top composition and the inlet line of the liquid-liquid extraction column, wherein the condenser includes an outlet line that divides into a circulation line for returning a portion of the condensate to the partition wall distillation column and a line leading to the at least one stripping column, the liquid outlet of which is connected to the inlet line of the liquid-liquid extraction column. ii) In the outlet line of the liquid-liquid extraction tower for the raffinate, iii) In the pipeline connecting the outlet line of the liquid-liquid extraction column to the inlet line of the distillation column, iv) In the second outlet line of a liquid-liquid separator connected to the outlet line of the distillation column for the top composition, wherein the liquid-liquid separator is preferably arranged downstream of a condenser located in the line connecting the outlet line of the distillation column for the top composition and the inlet line of the liquid-liquid separator, and v) Upstream of the inlet line for the crude composition in the partition wall distillation column.
[0044] The invention is then described with reference to exemplary but non-limiting drawings, in which: Figure 1 This is a schematic diagram of an apparatus for removing water from a crude composition containing water, phenol, and bisphenol A according to one embodiment of the present invention.
[0045] Figure 2a and Figure 2b yes Figure 1 A schematic cross-sectional view along the length of a portion of the liquid-liquid extraction column of the apparatus shown.
[0046] An apparatus 10 for removing water from a crude composition containing water, phenol, and bisphenol A includes a partitioned-wall distillation column 12, a liquid-liquid extraction column 14, a distillation column 16, and a liquid-liquid separator 18. The partitioned-wall distillation column 12 is an intermediate partitioned-wall distillation column 12, comprising a partition wall 20 extending vertically downwards from a point below the top of the distillation column 12 to a point above the bottom of the partitioned-wall distillation column 12. This subdivides the partitioned-wall distillation column 12 into a top section above the partition wall 20, a bottom section below the partition wall 20, and an intermediate section, the intermediate section including a first intermediate sub-section to the left of the partition wall 20 and a second intermediate sub-section to the right of the partition wall 20. The partitioned-wall distillation column 12 also includes an inlet line 22 for the crude composition, an outlet line 24 for the top composition, an outlet line 26 for the side-stream composition, and an outlet line 28 for the bottom composition. The outlet line 24 for the top composition is connected to a condenser (not shown) and is divided into a circulation line 30 leading to the partition wall distillation column 12 and a connecting line 32. The liquid-liquid extraction column 14 includes an inlet line 34 connected to the connecting line 32, an inlet line 36 for the extractant, an outlet line 38 for the extractant, and an outlet line 40 for the raffinate. The distillation column 16 includes an inlet line 42 connected to the outlet line 38 for the extractant of the liquid-liquid extraction column 14, an inlet line 44 connected to the outlet line 26 for the side-stream composition of the partition wall distillation column 12, an inlet line 46 for the extractant, an outlet line 48 for the top composition, and an outlet line 50 for the bottom composition. Finally, the liquid-liquid separator 18 includes an inlet line 52, a partition wall 53, a first outlet line 54, and a second outlet line 56. The inlet line 52 of the liquid-liquid separator 18 is connected to the outlet line 48 of the distillation column 16 for the top composition, while the first outlet line 54 of the liquid-liquid separator 18 is connected to the inlet line 36 of the liquid-liquid extraction column 14 for the extractant and to the inlet line 46 of the distillation column 16 for the extractant. The second outlet line 56 is a discharge line.
[0047] During operation of unit 10, a crude composition containing bisphenol A, acetone, water, and phenol is fed through inlet line 22 to a partitioned wall distillation column 12, where the crude composition is distilled into a top composition rich in water and also containing acetone and phenol residues, a side stream composition rich in phenol, and a bottom composition (a dehydrated bisphenol A composition). The top composition is then condensed, with a portion of the condensed top composition being recycled back to the partitioned wall distillation column 12 through circulation line 30, while another portion is introduced into the upper section of liquid-liquid extraction column 14 through lines 24, 32, and 34. An extractant (i.e., ethylbenzene) is fed through inlet line 36 to the lower section of liquid-liquid extraction column 14, which extracts phenol from the top composition into an extractant composition, which is discharged from the upper section of liquid-liquid extraction column 14 through outlet line 38. The raffinate composition, low in phenol and high in water, is discharged from the lower section of the liquid-liquid extraction column 14 via outlet line 40. The extract composition, primarily containing ethylbenzene, phenol, and small amounts of water and acetone, is introduced into the distillation column 16 via lines 38 and 42. Meanwhile, the phenol-rich side stream composition discharged from the partition wall distillation column 12 is introduced into the distillation column 16 via lines 26 and 44, and ethylbenzene, used as an extractant, is introduced into the distillation column 16 via inlet line 46. These two compositions are distilled in the distillation column 16 to obtain a phenol-rich bottom composition discharged from the distillation column 16 via outlet line 50 and an ethylbenzene-rich and water-containing top composition discharged from the distillation column 16 via outlet line 48. The ethylbenzene-rich and water-containing top composition is introduced into a liquid-liquid separator 18, where it is separated by gravity into a first liquid composition primarily composed of ethylbenzene and a second liquid composition primarily composed of water. The second liquid composition is discharged from the device 10, while the first liquid composition is partially recycled back to the distillation column 16 as an extractant through pipelines 54 and 46, and the remaining portion of the first liquid composition is recycled back to the liquid-liquid extraction column 14 as an extractant through pipelines 54 and 36.
[0048] Figure 2a and Figure 2b schematically shown Figure 1 The diagram shows a cross-sectional view along the length of a portion of the liquid-liquid extraction column 14 of the apparatus 10. The liquid-liquid extraction column 14 is defined by a wall 58 and includes a plurality of compartments 60, 60', 60'', wherein... Figure 2a Three were shown in the middle. Figure 2bOne is shown in the image. Each compartment 60, 60', 60'' is separated from adjacent compartments 60, 60', 60'' by static partitions 62, 62', 62''', 62'''. Each static partition 62, 62', 62''', 62''' is perforated (not shown), i.e., contains several holes that allow liquid to pass through from one side of the partition 62, 62', 62''', 62''' to the other side. Furthermore, the liquid-liquid extraction column 14 includes a rotating shaft 64 extending through each compartment 60, 60', 60'' and arranged at the center of each compartment 60, 60', 60'' in a cross-sectional view along its length. The rotating shaft 64 includes several turbine impellers serving as agitators 66, with each compartment 60, 60', 60'' containing two agitators 66.
[0049] like Figure 2b As shown in more detail, it illustrates Figure 2a The section of the liquid-liquid extraction column 14 highlighted in the middle frame 68, during operation of the liquid-liquid extraction column 14, sees the extractant flowing through it in the directions of arrows 70 and 72', while the overhead composition obtained in the partition wall distillation column 12 flows in the opposite direction as indicated by arrows 72 and 70'. The mixture of the overhead composition and the extractant is stirred by a rotating agitator 66, where the rapid flow along the length is restricted by perforated baffles 62, 62', 62'', thereby creating an elliptical flow pattern in the cross-section along the length, as indicated by arrows 74 and 74'. This achieves close contact between the overhead composition and the extractant, thereby extracting phenol from the composition into the extractant particularly efficiently.
[0050] Figure Labels
[0051] 10 devices
[0052] 12. Distillation column with partitioned wall
[0053] 14 Liquid-Liquid Extraction Column
[0054] 16 Distillation Column
[0055] 18 Liquid-Liquid Separator
[0056] 20 partition walls
[0057] 22. Inlet line for crude composition in a partitioned wall distillation column
[0058] 24. Outlet line for top composition of a partitioned wall distillation column
[0059] 26. Outlet line for side-stream composition in a partitioned wall distillation column
[0060] 28. Outlet line for bottom composition of partitioned wall distillation column
[0061] 30 Circulation Pipeline
[0062] 32 Connecting pipelines
[0063] 34. Inlet pipeline of liquid-liquid extraction tower
[0064] 36. Inlet piping for the extractant in a liquid-liquid extraction tower.
[0065] 38. The outlet pipeline for the extractant in a liquid-liquid extraction tower.
[0066] 40. The outlet pipeline for the raffinate in the liquid-liquid extraction column.
[0067] 42. Inlet pipeline of the distillation column
[0068] 44. Inlet pipe of the distillation column
[0069] 46. Inlet line for extractant in distillation column
[0070] 48. The outlet line for the top composition of the distillation column.
[0071] 50. Outlet line for the bottom composition of the distillation column.
[0072] 52. Inlet pipeline of liquid-liquid separator
[0073] 53 Separation Wall
[0074] 54. First outlet pipeline of the liquid-liquid separator
[0075] 56. Second outlet pipeline of the liquid-liquid separator
[0076] 58. Wall of a liquid-liquid extraction tower
[0077] 60', 60'' compartments of the liquid-liquid extraction column
[0078] 62, 62', 62'', 62''' Static partitions
[0079] 64 Rotation axis
[0080] 66 Mixer
[0081] 68 Figure 2b Part of the liquid-liquid extraction tower shown
[0082] 70 and 72' are arrows indicating the direction of extractant flow.
[0083] 72 and 70' are arrows indicating the direction of composition flow at the top of the tower.
[0084] Arrows 74 and 74' indicate the flow patterns within the compartments.
Claims
1. A method for removing water from a crude composition containing water, phenol, and bisphenol A, wherein the method comprises the following steps: a) The crude composition is fed into a partitioned-wall distillation column and distilled therein to obtain a top composition, a side-stream composition, and a bottom composition, wherein the bottom composition is a dehydrated bisphenol A composition. b) The top composition obtained in step a) is subjected to liquid-liquid extraction with an extractant in an extraction column to obtain a water-rich raffinate composition and a phenol-rich extract composition, and c) The extract composition obtained in step b), the side stream composition obtained in step a), and the same extractant used in step b) are fed separately into a distillation column and distilled therein to obtain a top composition containing extractant and water and a bottom composition containing phenol.
2. The method of claim 1, wherein the crude composition contains, based on 100% by weight, 15 to 35% by weight of bisphenol A, 1 to 5% by weight of water, 0.5 to 5% by weight of acetone and 60 to 80% by weight of phenol, preferably 20 to 30% by weight of bisphenol A, 1.5 to 2.0% by weight of water, 0.8 to 2.9% by weight of acetone and 65 to 75% by weight of phenol.
3. The method of claim 1 or 2, wherein in step a), the crude composition is fed into an intermediate partition wall distillation column, the intermediate partition wall distillation column comprising a partition wall extending at least substantially vertically downward from a point located below the top of the distillation column to a point located above the bottom of the partition wall distillation column, thereby subdividing the partition wall distillation column into a top section above the partition wall, a bottom section below the partition wall, and an intermediate section, the intermediate section comprising a first intermediate sub-section located on one side of the partition wall and a second intermediate sub-section located on the opposite side of the partition wall.
4. The method of any of the preceding claims, wherein the dehydrated bisphenol A composition contains 20 to 40% by weight of bisphenol A, 60 to 80% by weight of phenol, up to 0.1% by weight of water and up to 0.1% by weight of acetone based on 100% by weight of the dehydrated bisphenol A composition.
5. The method as described in any of the preceding claims, wherein the extractant used in steps b) and c) is selected from the group consisting of methyl isobutyl ketone, diisopropyl ether, ethylbenzene, toluene, hexane, octane, benzene, heptane, cyclohexane, hexadecane, and any combination of two or more of the above compounds.
6. The method of any of the preceding claims, wherein the liquid-liquid extraction in step b) is carried out in a stirred extraction tower, preferably in a stirred countercurrent extraction tower, wherein the stirred extraction tower comprises one or more rotating shafts, each rotating shaft comprising one or more agitators, the agitators preferably selected from the group consisting of: discs, blades, impellers, turbine impellers, fins, and any combination of two or more of the above agitators.
7. The method of claim 6, wherein the stirred extraction tower comprises two or more compartments separated from each other by static partitions, wherein at least some and preferably all of the compartments comprise a rotating shaft with one or more stirrers, the stirrers preferably selected from the group consisting of: discs, blades, impellers, turbine impellers, fins, and any combination of two or more of the above stirrers.
8. The method as claimed in any of the preceding claims, wherein the raffinate composition obtained in step b) contains 90 to 99.99% by weight, preferably 95 to 99.99% by weight, of water and 0 to 1% by weight, preferably 0.01 to 0.1% by weight, of 100% by weight of the raffinate composition.
9. The method of any of the preceding claims, wherein in step c), the extractant is fed into the distillation column at a position above the position where the extract composition obtained in step b) is fed into the distillation column, wherein the position where the extract composition obtained in step b) is fed into the distillation column is above the position where the side-stream composition obtained in step a) is fed into the distillation column.
10. The method of any of the preceding claims, wherein the overhead composition obtained in step c) is introduced into a liquid-liquid separator, in which the overhead composition is separated into a first liquid composition and a second liquid composition, wherein the first liquid composition is rich in extractant and has a lower density than the second liquid composition rich in water, and wherein the first liquid composition is fed at least partially as extractant to the distillation column used in step c), wherein a portion of the first liquid composition is fed as extractant to the distillation column used in step c), and another portion of the first liquid composition is fed as extractant to the liquid-liquid extraction column used in step b).
11. The method of any of the preceding claims, further comprising a stripping step for removing acetone, wherein the stripping step is performed on one or more of the following compositions: i) The top composition obtained in step a), from which acetone has been at least partially vaporized, before the remaining composition is introduced into the liquid-liquid extraction column of step b). ii) The raffinate composition obtained in step b), iii) The extract composition obtained in step b), from which acetone has been at least partially vaporized, before introducing the remaining composition into the distillation column of step c). iv) The top composition obtained in step c), and v) The crude composition before being fed into the partition wall distillation column of step a).
12. An apparatus for removing water from a crude composition containing water, phenol, and bisphenol A, wherein the apparatus comprises: a) A partitioned-wall distillation column, comprising an inlet line for a crude composition, an outlet line for a top composition, an outlet line for a side-stream composition, and an outlet line for a bottom composition. b) A liquid-liquid extraction column, comprising an inlet line directly or indirectly connected to an outlet line for the top composition of a partitioned wall distillation column, an inlet line for the extractant, an outlet line for the extractant, and an outlet line for the raffinate, and c) A distillation column, comprising an inlet line directly or indirectly connected to the outlet line of a liquid-liquid extraction column for the extractant, an inlet line connected to the outlet line of a partitioned wall distillation column for the side-stream composition, an inlet line for the extractant, an outlet line for the top composition, and an outlet line for the bottom composition.
13. The apparatus of claim 12, further comprising a liquid-liquid separator including an inlet line, a first outlet line, and a second outlet line, wherein the inlet line of the liquid-liquid separator is directly or indirectly connected to an outlet line of the distillation column for the top composition, and wherein the first outlet line of the liquid-liquid separator is connected to an inlet line of the liquid-liquid extraction column for the extractant and to an inlet line of the distillation column for the extractant.
14. The apparatus of claim 12 or 13, wherein the partition wall distillation column is an intermediate partition wall distillation column comprising a partition wall extending at least substantially vertically downward from a point located below the top of the distillation column to a point located above the bottom of the partition wall distillation column, thereby subdividing the partition wall distillation column into a top section above the partition wall, a bottom section below the partition wall, and an intermediate section, the intermediate section comprising a first intermediate sub-section located on one side of the partition wall and a second intermediate sub-section located on the opposite side of the partition wall.
15. The apparatus of any one of claims 12 to 14, further comprising at least one stripping tower for removing acetone, wherein the at least one stripping tower is arranged in any of the following locations: i) In the pipeline connecting the outlet line of the partition wall distillation column for the top composition and the inlet line of the liquid-liquid extraction column, preferably downstream of a condenser in the pipeline connecting the outlet line of the partition wall distillation column for the top composition and the inlet line of the liquid-liquid extraction column, wherein the condenser includes an outlet line that divides into a circulation line for returning a portion of the condensate to the partition wall distillation column and a line leading to the at least one stripping column, the liquid outlet of which is connected to the inlet line of the liquid-liquid extraction column. ii) In the outlet line of the liquid-liquid extraction tower for the raffinate, iii) In the pipeline connecting the outlet line of the liquid-liquid extraction column to the inlet line of the distillation column, iv) In the second outlet line of a liquid-liquid separator connected to the outlet line of the distillation column for the top composition, wherein the liquid-liquid separator is preferably arranged downstream of a condenser located in the line connecting the outlet line of the distillation column for the top composition and the inlet line of the liquid-liquid separator, and v) Upstream of the inlet line for the crude composition in the partition wall distillation column.