Method for recovering light and heavy boiling components from a vapor stream

Abstract

The present invention relates to a method for recovering light and heavy boiling components from a vapor stream, comprising the steps of: A1) introducing a vapor stream (1) comprising light and heavy boiling components into a column (2) at the bottom of said column (2); A2) withdrawing a vapor stream (3) enriched in light boiling components from the top of column (2); A3) withdrawing a liquid stream (4) enriched in heavy boiling components from the bottom of column (2) and dividing liquid stream (4) into a partial stream (5) and a partial stream (6); A4) recycling partial stream (5) back to column (2) at a location above column (2), wherein partial stream (5) is A5) withdrawing a stream (7) enriched in medium boiling components from the middle of the column (2) and dividing the stream (7) into a partial stream (8) and a partial stream (9); A6) cooling the partial stream (9) in a heat exchanger (10) to provide a cooled stream (11) and recycling the stream (11) as a stream (12) back into the column (2) at an inlet point below the top of the column (2); and A7) withdrawing the partial stream (6) enriched in heavy boiling components and the partial stream (8) enriched in medium boiling components.

Description

Technical Field

[0001] The present invention relates to a method for recovering a light-boiling component and a heavy-boiling component from a vapor stream containing the light-boiling component and the heavy-boiling component. Specifically, the method of the present invention can improve the recovery of the heavy-boiling component as compared with the methods of the prior art. Preferably, the present invention relates to a method for recovering acrolein and acrylic acid from a vapor containing acrolein and acrylic acid while improving the recovery of acrylic acid formed as a by-product in the oxidation of propene to acrolein.

[0002] On an industrial scale, many organic products, such as ketones or aldehydes, are produced by partial gas-phase oxidation of organic precursor compounds. However, the main side reaction of the partial gas-phase oxidation of organic compounds is that the desired product is further oxidized to a by-product, particularly from an aldehyde to a carboxylic acid. Therefore, in order to obtain the desired product with the required purity, the vapor stream from this oxidation reaction needs to be subjected to a purification process. In the purification processes of the prior art, the desired product can be recovered at least with an acceptable purity, but usually, the by-products cannot be recovered at concentrations that would be particularly attractive from an economic point of view. Although the by-products may also be valuable materials in some cases, they are lost due to the deficiencies of the purification processes of the prior art.

[0003] For example, on an industrial scale, acrolein is produced by the selective oxidation of propene in the gas phase in the presence of a heterogeneous catalyst. The main side reaction in this method is the oxidation of the desired product to acrylic acid. After leaving the reactor, the high-temperature gaseous product stream is cooled with water in a quenching tower. The function of the quenching tower is to stop further reactions and absorb by-products from the gaseous product stream, thus facilitating the separation of the reaction gas from high-boiling components, mainly water and acrylic acid. A typical conventional acrolein quenching tower for purifying acrolein is shown in Figure 5 below. In a typical conventional quenching tower, the high-temperature gas produced by the oxidation of propene enters the quenching tower in the sump section and is cooled via a heat exchanger by a so-called sump-pump-around recirculation stream. The resulting load water stream is supplied to a stripping tower, where it is stripped by the recirculated gas and the absorbed acrolein is recovered. The remaining load water stream contains approximately 14-18% by weight of acrylic acid. Typically, acrylic acid still present in a loaded water stream is a valuable material worth recovering. However, the concentration of acrylic acid in such a stream is relatively low. Therefore, on an industrial scale, recovering acrylic acid from a loaded water stream is not attractive. Consequently, water streams containing acrylic acid are usually sent to thermal oxidation equipment, which typically means the loss of a valuable material.

[0004] Therefore, an improved method was needed that would enable not only the recovery of light-boiling components but also the improved recovery of heavy-boiling components.

[0005] This problem was found to be solved by turning off the cooling of the sump pump-around in the purification process and substantially adiabatically maintaining the flow that is recirculated back to the bottom of the column. The substantially adiabatically maintained flow recirculation increases the temperature of the sump in the column compared to conventional methods. As a result, there is less condensation in the column, and therefore a significant reduction in the flow of condensed light-boiling and medium-boiling components returning to the sump in the column. This concentrates the heavy-boiling components in the sump. The cooling lost by the sump pump-around is compensated for by the cooling by the upper pump-around. This upper pump-around includes withdrawing the flow (7) from the middle section of the column (2), splitting the flow (7) into a withdrawn partial flow (8) and a partial flow (9), cooling the partial flow (9) in a heat exchanger (10) to supply a cooled flow (11), and recirculating the flow (11) as flow (12) back to the column (2) at an introduction point below the top of the column (2).

[0006] Therefore, the object of the present invention is a method (A) for recovering light-boiling and heavy-boiling components from a vapor stream, A1) A process of introducing a steam stream (1) containing light boiling components and heavy boiling components into a tower (2) at the bottom of the tower (2), A2) A process of extracting the steam stream (3) enriched with light boiling components from the top of the tower (2), A3) A step of extracting the liquid stream (4) enriched with deuterating components from the bottom of the column (2), and dividing the liquid stream (4) into a partial stream (5) and a partial stream (6) enriched with deuterating components. A4) A process of recirculating the partial flow (5) back into the tower (2) at a position above the base of the tower (2), wherein the partial flow (5) is substantially adiabatically maintained during the recirculation process. A5) A process of extracting the flow (7) enriched with intermediate boiling components from the middle part of the tower (2), and dividing the flow (7) into a partial flow (8) and a partial flow (9), A6) A step of cooling the partial flow (9) in the heat exchanger (10), supplying the cooled flow (11), and returning the flow (11) as flow (12) to the tower (2) at an introduction position below the top of the tower (2), and A7) A method that includes a step of extracting a partial stream (6) enriched with heavy boiling components and a partial stream (8) enriched with medium boiling components.

[0007] In the context of the present invention, liquid flow (4) and partial flow (5) form a sump pump-around, and flow (7), partial flow (9), flow (11), and flow (12) form an upper pump-around.

[0008] Partial flow (6) is enriched with deuterated components. Compared with the conventional method, the method of the present invention makes it possible to increase the concentration of deuterated components, such as acrylic acid, in partial flow (6). This is shown in the examples of the present invention. Partial flow (8) is enriched with mesoute components.

[0009] The method according to the present invention is also shown in Figure 1 below.

[0010] According to the present invention, the temperature of the partial flow (5) introduced into the tower (2) in step A5), i.e., the temperature of the partially flow (5) thus recirculated, is substantially adiabatically maintained. Therefore, in contrast to the prior art method, in the method according to the present invention, the heat exchanger for the sump pump-around through which the partially flow (5) is recirculated may be completely shut off or even absent altogether.

[0011] In the context of the present invention, the column (2) is preferably operated to have a quenching section at its bottom, a distillation section in its middle portion, and another quenching section at its top.

[0012] In the context of the present invention, the term "packing" is used as is known to those skilled in the art in chemical engineering and refers to any kind of random or structured packing, and plates or trays used to bring the gas phase and liquid phase in a column into close contact.

[0013] In the context of the present invention, introducing or recirculating a flow into a tower includes, for example, distributing the flow of interest by a liquid distributor.

[0014] In the context of the present invention, the position where the flow (7) is withdrawn from the tower (2) is also referred to as the lateral withdrawal of the flow (7).

[0015] Inside column (2), the intermediate-boiling and heavy-boiling components condense and flow downward into the column's sump. In most cases, the condensation of these components occurs along the height of the packing in column (2). Therefore, it is preferable to withdraw the flow (7) in the middle portion of the packing in column (2). This allows the use of a recirculating fluid flow in the upper pump-around.

[0016] In one embodiment of the method according to the present invention, the flow (7) is withdrawn in the middle portion of the packing in the tower (2).

[0017] As the cooling of the sump pump-around flow, i.e., the partial flow (5), is lost, the amount of liquid inside the column (2) decreases. In other words, if the cooling lost by the sump pump-around flow is not compensated for by the upper pump-around, the liquid flow (4) and partial flow (6) cannot be extracted from the bottom of the column (2). However, the upper pump-around implemented in steps A5) and A6) of the method according to the present invention not only compensates for the cooling lost by the sump pump-around, but also allows for adjustment of the amount or volume of liquid flow (6) extracted as a partial flow from the bottom of the column (2) or the sump. Preferably, the amount or volume of partial flow (8) extracted as a partial flow in step A7) is equal to the amount or volume of partial flow (6) extracted in step A7).

[0018] In one embodiment of the method according to the present invention, the amount of partial flow (6) extracted in step A7) is adjusted by the amount of partial flow (8) extracted in step A7).

[0019] The liquid in column (2), particularly the mesoboiling and deuterating components, can be reversed in various ways. One option is to install a liquid collector, a liquid overflow (drainpipe), and a liquid distributor in the middle of column (2) to extract the flow (7), thereby allowing any condensed liquid to flow downward toward the column's sump. In addition to or instead of this option, a partial flow (13) can be separated from the flow (11) and reversed by introducing the partial flow (13) into column (2) at a lower position than the lateral extraction of the flow (7). After being introduced into column (2), this partial flow (13) flows downward toward the column's sump. In principle, it is also possible to separate any further partial flows from the flow (11) and introduce them into column (2) in the same way as the partial flow (13).

[0020] In another embodiment, also shown in Figure 2 below, the method according to the present invention is: B1) A step of separating the flow (11) into at least one further subflow (13), and B2) The process further includes introducing a partial flow (13) into the tower (2) at a position lower than the position from which the flow (7) is extracted in the tower (2).

[0021] Partial flows (12) and (13) are liquid flows. Therefore, after being introduced into tower (2), they flow downward through tower (2).

[0022] In a further embodiment of the method according to the present invention, the flow (12) and / or partial flow (13) after being introduced into the tower (2) are directed countercurrent to the rising steam.

[0023] In the context of this invention, the term "rising steam" is used as is known to those skilled in the art in chemical engineering and refers primarily to rising steam containing light boiling components.

[0024] In an embodiment in which the method according to the invention further comprises steps B1) and B2), the stream (12) is introduced to the column (2) at a position higher than the position where the stream (7) is withdrawn, and the partial stream (13) is introduced at a position lower than the withdrawn stream (7).

[0025] According to the invention, a liquid stream (4) enriched with a boiling component is withdrawn from the bottom of the column (2), a partial stream (6) is split off from this liquid stream (4) and then withdrawn. In principle, this partial stream (6) can be subjected to further treatment of the boiling components contained therein. However, preferably, prior to this, the partial stream (6) is subjected to a further purification step (C) to remove any residual light boiling components from the partial stream (6). This purification step is preferably carried out in a column (14), preferably a stripping column, using a purge gas stream (15) to remove any light boiling components, thereby obtaining a stream (16) containing light boiling components, withdrawing this stream (16) from the column (14) and recycling it back to the column (2), and the stream (17) from which the light boiling components have been removed may be subjected to further treatment after being withdrawn from the column (14).

[0026] In another embodiment, also shown in Figure 3 below, the method according to the invention comprises C1) introducing the partial stream (6) to the column (14) at a position below the top of the column (14); C2) purging the partial stream (6) with a gas stream (15) inside the column (14) to recover residual light boiling components from the partial stream (6); C3) withdrawing the stream (16) containing light boiling components from the top of the column (14) and introducing the stream (16) to the column (2) at a position above the bottom of the column (2); and C4) further comprising withdrawing the stream (17) from which the light boiling components have been removed from the bottom of the column (14).

[0027] According to the present invention, the stream (7) is withdrawn in the middle part of the column (2), preferably at the height of the packing in the column (2), and is divided into a partial stream (8) and a partial stream (9), the partial stream (9) being first cooled and then recycled back to the column (2) at an introduction point below the top of the column (2). Thus, the stream (7) and the partial stream (8) mainly contain the intermediate-boiling components of the vapor stream (1). If one or more of the intermediate-boiling components are valuable materials, the partial stream (8) can be fed to another manufacturing process. However, prior to this, it is preferable to subject the partial stream (8) to a further purification step (D) to remove any remaining light-boiling components from the partial stream (8). This purification step is preferably carried out in a column (18), preferably a stripper column, using a purge gas stream (19) to remove any light-boiling components, thereby obtaining a stream (20) containing light-boiling components, withdrawing this stream (20) from the column (18), and the stream (21) from which the light-boiling components have been removed, after being withdrawn from the column (18), may be subjected to further treatment. The stream (20) containing light-boiling components may be recycled back to the column (2) and introduced into the column (2) at a position above the bottom of the column (2). Alternatively, the stream (20) may be sent for incineration.

[0028] In a further embodiment also shown in Figure 4 below, the method according to the invention comprises D1) introducing the partial stream (8) into the column (18) at a position below the top of the column (18), D2) purging the partial stream (8) with a gas stream (19) inside the column (18) to recover residual light-boiling components from the partial stream (8), D3) withdrawing the stream (20) containing light-boiling components from the top of the column (18), and D4) further comprising withdrawing the stream (21) from which the light-boiling components have been removed from the bottom of the column (18).

[0029] In principle, the method according to the invention is not limited with respect to the origin and composition of the vapor stream (1) in step A1), as long as the vapor stream contains light-boiling components and heavy-boiling components.

[0030] However, it is preferable that the vapor stream (1) is generated from the oxidation of an organic compound selected from the group consisting of olefins, aliphatic alcohols, aliphatic aldehydes, allyl alcohols, allyl aldehydes, and allyl ketones.

[0031] Preferably, the vapor flow (1) is due to the oxidation of propene to acrolein, with acrylic acid as the main by-product.

[0032] In one embodiment of the method according to the present invention, the light-boiling component contains or consists of acrolein, and the heavy-boiling component contains or consists of acrylic acid.

[0033] In the context of this invention, in addition to acrylic acid, which is the main heavy boiling component, the heavy boiling components may also include water and other heavy boiling components, but may also include small amounts of allyl acrylate, allyl alcohol, and acetic acid.

[0034] Before applying the method according to the present invention, the high-temperature vapor stream generated by the oxidation of propene to acrolein is first cooled in the final stage of the reactor, and then rapidly cooled with water after leaving the reactor to stop further reactions, particularly the oxidation of the formed acrolein.

[0035] In another embodiment of the method according to the present invention, the vapor flow (1) also contains water. This water condenses in the tower (2), specifically at the height of the packing in the middle portion of the tower (2). Thus, water is also present in the flow (7).

[0036] In a preferred embodiment of the method according to the present invention, the flow (7) extracted in step A5) contains water.

[0037] In addition to water, the stream (7) may contain small amounts of light-boiling components, such as acrolein, formaldehyde, and acetaldehyde residues, as well as small amounts of heavy-boiling components, such as acrylic acid.

[0038] Due to the substantially adiabatically maintained partial flow (5), the method according to the present invention results in a higher temperature at the bottom of the column (2) or in the sump compared to the conventional method. For example, if the vapor flow (1) is produced by the oxidation of propene and therefore contains acrolein as a light-boiling component and acrylic acid as a heavy-boiling component, the following temperature changes are observed in the column (2): the temperature at the bottom of the column or in the sump rises from about 65°C (conventional method) to a temperature in the range of about 70-85°C, preferably above 70°C, for example, in the range of 70°C-85°C, or at least 75°C, for example, in the range of 75-85°C, or particularly in the range of 80-85°C. As a result, the liquid flow (4) withdrawn from the bottom of the column (2) or in the sump, and the partial flow (5) separated from the liquid flow (4) and substantially adiabatically maintained when recirculated back into the column (2), also have a temperature in the range of 70-85°C. As a further consequence of substantially adiabatically maintaining the partial flow (5), a temperature rise also occurs at the level of the packing inside the tower (2): the temperature rises from approximately 48°C (conventional methods) to a range of 50-70°C.

[0039] In a preferred embodiment of the method according to the present invention, the temperature at the bottom of the column (2) is in the range of 70 to 85°C.

[0040] In another preferred embodiment of the method according to the present invention, the temperature of the partial flow (5) is in the range of 70 to 85°C.

[0041] If the sump is not cooled, a significant temperature rise is expected at the top of column (2). However, the upper pump-around implemented in steps A5) and A6) of the method according to the present invention results in at most a very small temperature rise, or no temperature rise at all, at the top of column (2). Specifically, this effect is achieved by the subsequent cooling of the flow (11), which is introduced as a partial flow (12), preferably as a partial flow (13) and any further partial flows, to a temperature of at most 20°C, preferably in the range of 10 to 20°C.

[0042] In a more preferred embodiment of the method according to the present invention, the flow (11) has a maximum temperature of 20°C.

[0043] The method according to the present invention will be further explained with reference to Figures 1 to 5 and the examples. [Brief explanation of the drawing]

[0044] [Figure 1] This is a schematic diagram of the method described in claim 1. [Figure 2] This is a schematic diagram of the method according to the embodiment described in claim 4. [Figure 3] This is a schematic diagram of the method according to the embodiment described in claim 7. [Figure 4] This is a schematic diagram of the method according to the embodiment described in claim 8. [Figure 5] This is a schematic diagram of a conventional method.

[0045] Figure 1 is a schematic diagram of the method according to claim 1, and the numbers are as follows: (1) A steam stream containing light boiling components and heavy boiling components, (2) Tower; (3) The light boiling components are enriched, and the steam stream is extracted from the top of the tower (2), (4) The heavy boiling component is enriched, and the liquid stream is extracted from the bottom of the column (2), (5) A partial flow separated from the liquid flow (4) and recirculated to the tower (2), (6) A partial flow separated from the liquid flow (4) and extracted from the said method, (7) The stream extracted from the middle section of tower (2), (8) Sub-flows separated from the flow (7), (9) A partial flow separated from the flow (7) and sent to cooling, (10) Heat exchanger, (11) Cooled flow, and (12) This refers to a flow that is cooled and recirculated.

[0046] Figure 2 is a schematic diagram of the method according to the embodiment described in claim 4, where the numbers are: (1) A steam stream containing light boiling components and heavy boiling components, (2) Tower; (3) The light boiling components are enriched, and the steam stream is extracted from the top of the tower (2), (4) The heavy boiling component is enriched, and the liquid stream is extracted from the bottom of the column (2), (5) A partial flow separated from the liquid flow (4) and recirculated to the tower (2), (6) A partial flow separated from the liquid flow (4) and extracted from the said method, (7) The stream extracted from the middle section of tower (2), (8) Sub-flows separated from the flow (7), (9) A partial flow separated from the flow (7) and sent to cooling, (10) Heat exchanger, (11) Cooled flow, (12) A partial flow that is separated from the cooled flow (11) and recirculated, (13) This refers to a partial flow that is separated from the cooled flow (11) and recirculated.

[0047] Figure 3 is a schematic diagram of the method according to the embodiment described in claim 7, and the numbers are as follows: (1) A steam stream containing light boiling components and heavy boiling components, (2) Tower; (3) The light boiling components are enriched, and the steam stream is extracted from the top of the tower (2), (4) The heavy boiling component is enriched, and the liquid stream is extracted from the bottom of the column (2), (5) A partial flow separated from the liquid flow (4) and recirculated to the tower (2), (6) A partial flow separated from the liquid flow (4) and extracted from the said method, (7) The stream extracted from the middle section of tower (2), (8) Sub-flows separated from the flow (7), (9) A partial flow separated from the flow (7) and sent to cooling, (10) Heat exchanger, (11) Cooled flow, (12) A partial flow separated from the cooled flow (11) and recirculated, (13) A partial flow that is separated from the cooled flow (11) and recirculated, (14) Tower (15) Gas flow for purging the partial flow (6), (16) A flow containing light boiling components, and extracted from the top of the tower (14), (17) This refers to the flow that has had the light boiling components removed and has been extracted from the bottom of the tower (14).

[0048] Figure 4 is a schematic diagram of the method according to the embodiment described in claim 8, and the numbers are as follows: (1) A steam stream containing light boiling components and heavy boiling components, (2) Tower; (3) The light boiling components are enriched, and the steam stream is extracted from the top of the tower (2), (4) The heavy boiling component is enriched, and the liquid stream is extracted from the bottom of the column (2), (5) A partial flow separated from the liquid flow (4) and recirculated to the tower (2), (6) A partial flow separated from the liquid flow (4) and extracted from the said method, (7) The stream extracted from the middle section of tower (2), (8) Sub-flows separated from the flow (7), (9) A partial flow separated from the flow (7) and sent to cooling, (10) Heat exchanger, (11) Cooled flow, (12) A partial flow separated from the cooled flow (11) and recirculated, (13) A partial flow that is separated from the cooled flow (11) and recirculated, (14) Strip Tower, (15) Gas flow for purging the partial flow (6), (16) A flow containing light boiling components, extracted from the top of the strip tower (14), (17) The flow from which the light boiling components have been removed and which has been extracted from the bottom of the strip tower (14), (18) Strip Tower, (19) Gas flow for purging partial flow (8), (20) A flow containing light boiling components, which is withdrawn from the top of the strip tower (18), and (21) This refers to the flow from which the light boiling components have been removed and which has been extracted from the bottom of the strip tower (14).

[0049] Figure 5 is a schematic diagram of the conventional method, and the numbers indicate: (30) A vapor stream containing light boiling components and heavy boiling components, (31) Tower; (32) The light boiling components are enriched, and the steam stream extracted from the top of the tower (31) (33) The heavy boiling component is enriched, and the liquid stream is extracted from the bottom of the column (31), (34) A partial flow separated from the liquid flow (33) and recirculated to the tower (31), (35) Heat exchanger for cooling the partial flow (34), (36) Cooled flow (34) (37) Partial flow separated from liquid flow (33), (38) Strip Tower, (39) Gas flow for purging partial flow (6), (40) A stream containing light boiling components, extracted from the top of the strip tower (38), (41) The flow from which the light boiling components have been removed and which has been extracted from the bottom of the strip tower (28), (42) A stream extracted from the middle section of the tower (31), (43) Sub-flows separated from the flow (42), (44) A partial flow that is separated from the flow (42) and sent for cooling, (45) Heat exchanger, (46) Cooled flow, (47) Sub-flows separated from the cooled flow (42), and (48) This refers to a partial flow separated from the cooled flow (42).

[0050] Examples The examples described herein are performed using computational process models based on the methods shown in Figure 3 (Example According to the Invention) and Figure 5 (Comparative Example). Process modeling is an established and reliable methodology used by engineers to simulate complex chemical processes prior to actual plant construction. In the context of the examples described herein, commercially available modeling software Aspen Plus® (Aspen Technology, Inc., 20 Crosby Roads, Bedford, Massachusetts 01730, USA) was used in combination with physical property data from public databases.

[0051] Comparative example: To illustrate the advantages of the method according to the present invention, the purification of an acrolein-containing stream was simulated using the method shown in the schematic diagram of Figure 5. The acrolein-containing gas stream (30) was introduced into the sump section of a column (31) and cooled via a heat exchanger (35) using a sump pump-around system (consisting of a liquid stream (33), a partial stream (34), and a stream (36)). The waste liquid (high-boiling component), a partial stream (37), was sent to a second column (38), a recirculating gas stripper, to recover the acrolein. The waste liquid from the recirculating gas stripper, a stream (41), was sent to a waste liquid tank by a pump (not shown). The high-temperature gas in the column (31) was further cooled by a heat exchanger (45) via an upper pump-around system consisting of a stream (42), a partial stream (44), a stream (46), a partial stream (47), and a partial stream (48). The acrolein-enriched vapor stream (32) was withdrawn from the top of the column and sent to an absorption unit (not shown) for further processing. The liquid stream (33) withdrawn from the bottom of column (31) contained 18.350% by weight of acrylic acid. The complete composition of the liquid stream (33) is shown in Table 1 below.

[0052] Examples of the present invention: Using the modeling software Aspen Plus®, the purification of an acrolein-containing stream was simulated according to the method shown in the schematic diagram of Figure 3. The acrolein-containing gas stream (1) was introduced into the sump section of column (2). In contrast to the comparative example, the sump pump-around (consisting of a liquid stream (4) and a partial stream (5)) was not cooled but was substantially adiabatically maintained. The partial stream (6), which was waste liquid (high boiling component), was sent to a second column (14), a recirculating gas stripper, to recover the acrolein. The stream (17), which was waste liquid from the recirculating gas stripper, was sent to a waste liquid tank via a pump (not shown). The hot gas in column (2) was cooled by a heat exchanger (10) via an upper pump-around consisting of stream (7), partial stream (9), stream (11), and partial stream (12). The acrolein-enriched vapor stream (3) was withdrawn from the top of the column and sent to an absorber (not shown) for further processing. The liquid stream (4) extracted from the bottom of column (2) contained 51.635% by weight of acrylic acid, which is approximately three times the weight percentage in the comparative example liquid stream (33). The complete composition of the partial stream (6) is shown in Table 1 below.

[0053] [Table 1]

Claims

1. 1. A process for recovering light and heavy boiling components from a vapor stream, comprising the steps of: A1) introducing a vapor stream (1) comprising low and heavy boiling components into a column (2) at the bottom of said column (2); A2) withdrawing the vapor stream (3) enriched in low boiling components from the top of the column (2); A3) withdrawing the liquid stream (4) enriched in heavy azeotropes from the bottom of the column (2) and dividing the liquid stream (4) into a partial stream (5) enriched in heavy azeotropes and a partial stream (6), A4) recycling said partial stream (5) back to said column (2) at a position above the bottom of said column (2), during which said partial stream (5) is maintained substantially adiabatically; A5) withdrawing a stream (7) enriched in intermediate boilers from the middle part of the column (2) and dividing said stream (7) into a partial stream (8) and a partial stream (9), A6) cooling said partial stream (9) in a heat exchanger (10) to give said cooled stream (11) and recycling said stream (11) back to said column (2) as stream (12) at an inlet point below the top of said column (2), and A7) withdrawing the partial stream (6) enriched in heavy boilers and the partial stream (8) enriched in medium boilers; A method comprising:

2. 2. The process according to claim 1, wherein said stream (7) is withdrawn at an intermediate portion of the packing in said column (2).

3. 3. The process according to claim 1 or 2, wherein the amount of the partial stream (6) withdrawn in step A7) is adjusted by the amount of the partial stream (8) withdrawn in step A7).

4. B1) splitting off at least one further partial stream (13) from said stream (11); and B2) introducing said partial stream (13) into said column (2) at a position below the position at which said stream (7) is withdrawn from said column (2); The method of claim 1 or 2, further comprising:

5. 3. The process according to claim 1, wherein the stream (12) and / or the partial stream (13) after being introduced into the column (2) are conducted countercurrently to the ascending vapor.

6. 5. The process according to claim 4, characterized in that the stream (12) is introduced into the column (2) at a position higher than the position at which the stream (7) is withdrawn and the partial stream (13) is introduced into the column (2) at a position lower than the withdrawn stream (7).

7. C1) introducing said partial stream (6) into the column (14) at a position below the top of said column (14); C2) purging said partial stream (6) with a gas stream (15) inside said column (14) to recover residual low boiling components from said partial stream (6), C3) withdrawing a stream (16) comprising low boiling components from the top of the column (14) and introducing the stream (16) into the column (2) at a position above the bottom of the column (2); and C4) withdrawing the stream (17) from which the low boiling components have been removed from the bottom of the column (14); The method of claim 1 or 2, further comprising:

8. D1) introducing said partial stream (8) into a column (18) at a position below the top of said column (18); D2) purging the partial stream (8) with a gas stream (19) inside the column (18) to recover residual low boiling components from the partial stream (8), D3) withdrawing a stream (20) containing light boiling components from the top of the column (18); and D4) withdrawing the stream (21) from which the low boiling components have been removed from the bottom of the column (18); Further comprising:

3. The method according to claim 1 or 2.

9. 3. The process according to claim 1 or 2, wherein the vapor stream (1) results from the oxidation of an organic compound selected from the group consisting of olefins, aliphatic alcohols, aliphatic aldehydes, allylic alcohols, allylic aldehydes, and allylic ketones.

10. 3. The process of claim 1, wherein the low boiling component comprises or consists of acrolein, and the high boiling component comprises or consists of acrylic acid.

11. The process according to claim 1 or 2, wherein the steam stream (1) also contains water.

12. 10. The process according to claim 9, wherein the stream (7) withdrawn in step A5) comprises water.

13. 11. The process according to claim 10, wherein the temperature at the bottom of the column (2) is in the range of from 70 to 85°C.

14. The process according to claim 13, wherein the temperature of the partial stream (5) is in the range of 70 to 85°C.

15. The process of claim 10, wherein the stream (11) has a temperature of at most 20°C.

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