MXPA06007363A - Method for obtaining raw-1,3-butadiene - Google Patents

Abstract

The invention relates to a method for obtaining raw-1,3-butadiene by extractive distillation with a selective solvent from a C4-fraction, containing C4-acetylenes as secondary components, in a partition column (TK) with a bottom evaporator (V1) inside of which a partition (T) is arranged in longitudinal direction of the column while forming a first partial area (A), a second partial area (B) and a lower shared column area (C), and to which an extractive wash column (K) is connected upstream therefrom. The invention is characterized in that the supply of energy into the partition column (TK) via the bottom evaporator (V1) is controlled in such a manner that a bottom flow (17) is drawn out from the partition column (TK), this bottom flow containing solvent loaded with C4-acetylenes whose proportion of 1,3-butadiene is limited in order to render the loss of 1,3-butadiene economically acceptable. The invention is also characterized in that the bottom flow (17) is fed to an acetylene degassing device (AG) and, inside this acetylene degassing device (AG), the C4-acetylenes are stripped out via the top and purified solvent is obtained in the form of a bottom flow (27).

Description

METHOD FOR OBTAINING 1.3-BUTADfEEiO UO REFINED The invention relates to a process for obtaining 1,3-butadiene not refined by extractive distillation with a selective solvent from a C4 cut comprising acetylenes.

C4 as secondary components in a split wall column or in thermally coupled columns. Due to small differences in the relative volatile elements of the components of the C4E cut, obtaining 1,3-butadiene from a C4 cut is a complicated distillation problem. Therefore * the separation is carried out by attractive distillation, that is to say a distillation with the addition of an extractor which has a higher boiling point than the mixture to be separated and which increases the differences in the relative volatile elements of the components that are going to be separated. The use of suitable extractors allows a fraction of 1, 3-butadiene unrefined from the mentioned cut-off C4 to be obtained through extractive distillation, and said fraction is further purified in purification distillation columns. In the present context, the unrefined 1 E3-butadiene refers to a hydrocarbon mixture that has been obtained from a C4 cut from which at least 90% by weight of the sum of butanes and butenes have been removed. , preferably of at least 98% by weight of the sum of butanes and butenes more preferably of at least 99% by weight of the sum of butanes and butenes, and simultaneously by at least 90% by weight of the C4 acetylenes, preferably at least 96% by weight of the C4 acetylenes, more preferably at least 99% by weight of the C4 acetylenes. Unrefined 1R3-butadiene contains 1,3-butadiene product of value frequently in a proportion of at least 80% by weight, preferably 90% by weight, more preferably more than 95% by weight, and the remainder They are impurities. Accordingly, pure 1, 3-butadiene means a hydrocarbon mixture containing the product of 1,3-butadiene value in a proportion of at least 98% by weight preferably of at least 99.5%. by weight, more preferably in the range between 99.7 and 99.9% in weight and the rest are impurity. DE-A 101 05 860 describes a process having a simplified construction design of the apparatus compared to the above processes: the cut C4 is separated into a partition wall column having a dividing wall extending to the end top of the partition wall column and an extractive wash column upstream of the partition wall column. According to the process of DE-A 101 05 660, a stream of solvent is degassed is extracted from the bottom of the partition wall column used for the extractive distillation. The term "solvent is degassed" is known to those skilled in the art working in extractive distillation to obtain 1,3-butadiene and refers to a selective solvent containing dissolved components from the C4 cut to be separated, specifically, the components that have the highest affinity for the selective solvent. These include, in particular, C4 acetylenes, in particular ethylacetylene and vinylacetylene. However, a stream of solvent that has only been semi-degassed could not be reciepted into the extractive distillation, since the acetylenes harmful to the specification would accumulate otherwise. It is therefore necessary to feed the lower stream drawn from the partition wall column, before recycling into the extractive distillation, initially to a degassing column, as described for example, by DE-A 27 24 365, which is operated at a lower pressure compared to the column from whose lower part the semi-degassed current is extracted. In the degassing column, the semi-dehydrated solvent stream is processed to obtain a purified solvent, that is, fully degassed at the bottom and a gaseous hydrocarbon stream at the top of the degassing column, which is recycled through a compressor inside. from the lower region of the extractive distillation column. The acetylenes are discharged through a side stream. However, according to the process of DE-A 27 24 365, the lower stream that is extracted from the dividing wall column and fed to the degassing column contains, in addition to the C4 acetylenes, considerable amounts of the product of value 1, 3-butadiene also. The 1,3-butadiene passes into the upper stream of the degassing column, which, in an economical mode of operation, can not be discarded, but is recycled through a compressor into the extractive distillation that is operated at a higher pressure compared to the degasser. The compressor has very high power consumption; the process of DE-A 27 24 365 was therefore anticipated on the previous processes, in which compressors were required that have three times the energy consumption. However, on the date of the request for DE-A 2? 24 365, those skilled in the art did not know that a process version that can dispense with the compressor can be achieved in a technically simple manner. DE-A 103 22 655 describes a process in which controlling the energy input into the wall column d ivision through the lower evaporator thereof and setting the number of theoretical plates in the region The lower combined column can be used to adjust the operation of the dividing wall column such that a lower stream can be withdrawn from the dividing wall column and already contains the purified solvent. Consequently, both the degassing column and the compressor to recycle the 1,3-butadiene stream within the extractive distillation become unnecessary. In the present context, ei solvent term purified solvent or fully degassed refers to a solvent that has been depleted in components through C4 cut to a degree that is suitable for use as a selective solvent for the extractive distillation of a C 4 cut , while it meets predefined specifications for 1,3-butadiene unrefined and refined 1. the key components in this context are C4 acetylenes, especially etiiacet? teno v? nílacetíieno. Accordingly, it is an object of the invention to provide an improved process for the extractive distillation of 1,3-butadiene in the operation without compressor, which in particular ensures less embedding in the columns, increased operational reliability and economic viability. Accordingly, we have found a process for obtaining 1, 3-butadiene unrefined via extractive distillation with a solvent selective from a C4 cut comprising C4 acetylenes as secondary components, the process is carried out in a column dividing wall having a lower evaporator, in which the dividing wall is positioned in the longitudinal direction of the column to form a first subregion, a second subregion and a lower combined column region, and which is positioned upstream of one extractive scrubbing column, which process comprises controlling the energy input into the column partition wall through the lower evaporator so that a lower current is extracted from the column partition wall and comprises solvent loaded with C4 acetylenes whose 1,3-butadiene ratio is restricted so that the loss of 1,3-butadiene is economically acceptable, and feed the lower stream to an acetylenes degasser and, in the acetylenes degasser, separate the higher C4 acetylenes and obtain the purified solvent as the lower stream. It has been found that it is possible to remove the predominant proportion of the hydrocarbons from the C4 cut in the split wall column, so that substantially only the hydrocarbons having the best solubility therein, ie the C4 acetylenes, remain therein. selective solvent. Therefore, it is necessary to remove C4 acetylenes only from the bottom stream from the dividing wall column to obtain a purified solvent which is advantageously recíelado within the extractive distillation. Since the content of 1,3-butadiene in the lower stream of the extractive distillation column can be reduced to lower values, it is economically justifiable not to recycle it again within the extractive, energy-intensive distillation of a compressor. The cut C4 which is used in the present context as a starting mixture is a mixture of hydrocarbons having predominantly four carbon atoms per molecule. The C4 cuts are obtained, for example, in the preparation of ethylene and / or propylene by thermal catalytic disintegration of a petroleum fraction such as liquefied petroleum gas, light petroleum or gas oil. The C4 cuts are also obtained in the catalytic dehydrogenating of n-butane and / or n-butene. In general, the C4 cuts comprise butanes, n-butene, isobutene, 1,3-butadiene and additionally small amounts of C3 and C5 hydrocarbons, and also butines, especially 1-butane / ethylacetylene) and butenin. { vinylacetylene). The content of 1,3-butadiene is, in general, from 10 to 80% by weight, preferably from 20 to 70% by weight, in particular from 30 to 60% by weight, while the content of vinyl. The ethylene and ethylene ethylene does not generally exceed 5% by weight. The useful extractors, that is to say selective solvents, for the extractive distillation already defined at the beginning in the present problem of separation, obtaining 1,3-butadiene from the cut C4, are generally substances or mixtures that have a greater point. of boiling than the mixture to be separated, and also a higher affinity for conjugated double bonds and triple bonds than for simple double bonds or individual bonds, preferably bipolar solvents, more preferably bipolar-aprotic. For reasons of the apparatus, preference is given to substances that have less corrosion, if any. Suitable selective solvents for the process according to the invention are, for example, butyrolactopa, nitriles such as acetonitrile, propionitrile, methoxypropionitrile, ketones such as acetone, furfurol, N-alkyl substituted lower alkyl amides such as d? I? Iet? lfor amide, diethylformamide, dimethylacetamide, diethylacetamide, N-formyimorpholine, N-substituted amino-amides (lactams) such as N-alkylpyrrothidones, especially N-methylpyrrolidone. In general, substituted N-alkyl lower aliphatic amides or N-alkyl substituted cyclic amides are used. Particularly advantageous are dimethylformamide, acetonitrile, furfuroi and in particular N-methylpyrrolidone. However, it is also possible to use mixtures of these solvents with one another, for example, of N-methylpyrrolidone with acetonitrile, mixtures of these solvents with cosolvents such as water and / or tert-butyl ethers, for example methyl tert-butyl ether , ethyl tert-butyl ether, propylene tert-butyl ether n- or isobutyl tert-butyl ether. The N-methylpyrrolidone, abbreviated at present as NMP, is particularly suitable, preferably in aqueous solution, in particular from 7 to 10% by weight of water, more preferably with 8.3% by weight of water. The extractive distillation is carried out in a dividing wall column in which a dividing wall is placed in the longitudinal direction of the column to form a first subregion, a second subregion and a lower combined column region and is connected to an extractive washing column. The partition wall columns are used in a known manner for more complex separation tasks, generally for mixtures of at least three components, in which the individual components are each obtained in pure form. They have a dividing wall, that is, usually a leaf. A flat metal that is aligned in the longitudinal direction of the column and avoids the mixing of liquid backflow and vapor currents in sub-regions of the column. In the present context, a partition wall column having a special configuration is used, whose dividing wall extends to the highest point of the column and therefore allows the mixing of the liquid and vapor streams only in the region of lower combined column. The first and second subregions are separated from one another by means of the dividing wall. In a manner known to those of skill in the art, the partition wall column can be replaced by thermally connected coupled columns in an appropriate manner. The extractive wash column is a countercurrent wash column. In all columns, there are no restrictions regarding the internal separation elements that can be used; For reasons of cost, preference is given to random packages. The acetylenes degasser is a separation column; the lower stream charged with C4 acetylenes from the extractive distillation is applied in the upper region of the acetylenes degasser and the C4 acetylenes are degassed in countercurrent with the hot rinse gas stream. Preferably, a water scrubber is attached to the acetylene degasser, in which solvent residues from the degassed acetylenes stream are washed with reflux and fresh water. The water scrubber is preferably dimensioned with significantly smaller diameter compared to the acetylene degasser. At the top of the water scrubber, a stream is obtained which compresses the C4 acetylenes and is condensed and partially applied back to the water scrubber as reflux, and otherwise discharged from the process, in particular fed to a pyrrhic still? zador or incinerated. The lower stream from the acetylenes deaerator comprises purified solvent and is preferably recrystallized within the extractive distillation. In a preferred process version, the cut C4 is fed to the first subregion of the dividing wall column, preferably within its middle region, the upper stream from the first sub-region of the dividing wall columns is fed towards the extractive washing column, within its lower region, - in the extractive washing column, a countercurrent extraction is carried out by charging with a first substream of the selective solvent in the upper region of the extractive washing column, - the components of the C4 cuts that have lower solubility qu & 1, 3-butadiene in the selective solvent are extracted through the upper part of the extractive washing column, - the lower stream from the extractive washing column is recycled within the upper region of the first subregion of the extractive column. dividing wall, a second substream of the selective solvent is fed to the dividing wall column in the upper region of the second subregion, - the upper product from the second subregion (B) of the dividing wall colu is extracted from the wall. or 1, 3-butadiene without retinal and - a lower stream that consists of solvent loaded with the C4 acetylenes, whose proportion of 1,3-butadiene is restricted so that the loss of 1, 3-bufadiene is economically acceptable, is extracted from the lower combined column region of the dividing wall column, - the lower stream (7) is fed to the acetylenes degasser (AG) in which the C4 acetylenes are stopped at the top and the purified solvent is obtained as the lower stream (27) and is recycled into the process. Therefore preference is given to the feed of the cut C4 to be separated towards the first subregion of the split wall column, more preferably within the middle region thereof; feeding the upper stream from the first subregion of the dividing wall column to the upstream extractive washing column upstream into the lower region of the column, carrying out a countercurrent extraction in the extractive washing column by charging with a First subcurrent of the selective solvent in the upper region of the extractive washing column, extract the components of the C4 cut that have a lower solubility than the 1,3-butadiene in the selective solvent through the upper part of the extractive washing column , more preferably in a condenser in the upper part of the extractive washing column, and partially applying it as reflux to the extractive washing column, extracting it in another way as a by-product predominantly comprising butanes and butenes, often referred to also as a refined 1. The feed of the lower stream of the extractive washing column, ie of a stream comprising, in addition to the selective solvent, 1,3-butadiene, butanes, butenes and the components of the C4 cut that have better solubility than the 1, 3 -butadiene in the selective solvent, within the upper region of the first subregion of the dividing wall column, by virtue of the mass transfer between this current and the cut C4 applied in vapor form in the upper region of the first sub-division of the dividing wall column, allows a counter-current extraction to be carried out with depletion of the components that have lower solubility in the selective solvent than 1,3-butadiene in the upper part of the first subregion of the wall column of division. At the lower end of the dividing wall column a vapor stream is obtained which, in addition to the 1,3-butadiene, comprises the components of the C4 cut, especially C4 acetylenes, which have better solubility in the selective solvent than the 1, 3-butad? Eno. These are washed out of the countercurrent rinsing steam stream with a second subcorridge of the selective solvent which is applied in the upper region of the second subregion of the dividing wall column. The upper vapor product from the second subregion of the dividing wall column is extracted, preferably by condensing it in a condenser in the upper part of the column, a sub-stream of the condensed upper stream is introduced as reflux towards the subregion. B of the dividing wall column and the condensed upper stream is otherwise extracted as 1, 3-butadiene without refining. In the lower combined column region, the solvent is degassed to obtain, in the lower part of the extractive distillation column, a solvent comprising the C4 acetylenes and 1,3-butadiene in a proportion thereof is economically acceptable. In the determination of the input energy required for this purpose through the lower evaporator of the extractive distillation column, the process engineer shall take into account the thermal stress capacity of the substance or the mixture of substance that has been used in the process. or the selective solvent in each specific case. When it is allowed by the heat stress capacity of the selective solvent, the temperature in the lower part of the extractive distillation column is advantageously set sufficiently high so that it is still possible to condense in the upper part of the extractive distillation column with non-expensive refrigerants, for example with river water. However, when the thermal stress capacity of the selective solvent used in the specific case is not sufficient at the temperature that would be necessary to obtain the solvent in the lower part, whose proportion of 1,3-butadiene is restricted so that loss of 1,3-butadiene is economically acceptable, it is necessary to work at a temperature at the bottom of the column which is still permissible for the selective solvent and consequently for cooling at the top of the column with a coolant more expensive than river water. A particularly preferred selective solvent is, as detailed above, NMP, preferably in an aqueous solution, in particular from 7 to 10% by weight of water, more preferably with 8.3% by weight of water. According to the prerequisite that NMP is used as the selective solvent, the temperature in the lower evaporator of the extractive distillation column is preferably set within the range between 150 and 210 ° C, more preferably at 178 ° C. Consequently, the upper pressure in the second subregion of the extractive distillation column configured as a dividing wall column is set within the range from 1 to 10 absolute bars., preferably from 2 to 5 absolute bars, more preferably 3.5 bars absolute. Preference is given to the operation of the acetylenes deaerator at a pressure in the range from 1 baria absolute to a maximum in the upper pressure in the dividing wall column (T). In principle it is not necessary to provide the recovery of the by-product composed of butanes and butenes, known as raffinate 1, in an upstream extractive washing column separated from the extractive distillation column. It is also possible to integrate the extractive washing column of the first subregion of the partition wall column used as an attractive distillation column, when it is technically and economically feasible to take into account the specific boundary conditions for the process, especially the composition of the cut C4 to be separated and the specification of the raffinate 1, in order to appropriately increase the number of theoretical plates in the first sub-region of the partition wall column. The preferred process variants described hereinafter, from the process of DE-A 101 05 660 are equally applicable also for the process of the present invention: In a preferred process variant, the vapor stream at the lower end of the dividing wall of the dividing wall column is divided by suitable measures such that the sub-current conveyed to the first subregion of the wall column of division is greater than the sub-current transported to the second subregion of the dividing wall column. The regulation of the vapor current division at the lower end of the partition wall allows the necessary product specification of the non-retinal 1,3-butadiene taken at the top of the second subregion of the partition wall column for be insured in a simple and reliable way. Said uneven division of the vapor stream at the lower end of the dividing wall is particularly preferably achieved by means of the dividing wall which is positioned non-centrally so that the second subregion is smaller than the first subregion of the second subregion. the dividing wall column. The dividing wall is particularly preferably non-central so that the cross-sectional ratio of the first subregion to the second subregion is in the range from 8: 1 to 1.5: 1, particularly 2.3: 1. As an alternative to or in addition to the non-central arrangement of the dividing wall, the vapor stream and the lower end of the dividing wall can be divided into the desired ratio between the two subregions of the dividing wall column through additional measures, for example fins or guide plates.

An additional or additional measure for dividing the vapor stream at the lower end of the dividing wall is to fix the heat removal energy of the condenser at the top of the second subregion of the dividing wall column. In a preferred process variant, the pressures at the upper end of the two subregions of the dividing wall column can each be regulated separately. This allows the required product specification of 1, 3-butadiene without retinal to be ensured. The pressures in the upper part of the two subregions of the dividing wall column are each preferably fixed by means of a separate range control. The term "separated range control" refers, in a well-known manner, to an arrangement in which the output of! Pressure regulator is connected simultaneously to the inert gas line and the ventilation line. The valve setting range of the pressure regulator is divided so that only one valve is actuated at the same time, ie the flow or ventilation of the inert gas is presented. This allows the amount of inert gas and losses of product associated with the waste air stream to be minimized. In addition to or as an alternative to the separate range control, it is possible to adjust each of the presses on the top of the two subregions of the dividing wall column by means of the heat removal energy of the condensers in the upper part of the second subregion of the dividing wall column and in the upper part of the extractive washing column. In a preferred variant, it is possible to integrate the acetylenes degasser by construction within the lower region of the partition wall column. For this purpose, the number of theoretical plates has to be increased appropriately in the lower combined column region and, at the point corresponding to the upper end of the acetylenes degasser, a gas-tight division in the column of dividing wall, although it is appropriate to ensure a liquid connection, for example by removing the liquid on the partition and feeding it below the partition. The heat content of the lower stream from the extractive distillation column can be used advantageously for thermal integration in the process itself, especially for heating by indirect heat transfer to the lower stream drawn from the acetylenes degassing plant and / or the liquid which is extracted from one or more separate stages of the partition wall column, heated and / or evaporated by indirect heat exchange. with the lower hot stream, and recycled within the lower combined column region of the dividing wall column and the. { s) separation step (s) is / are advantageously selected in such a way that the total energy requirement for the extractive distillation column is minimal. Additionally or alternatively, the heat content of the lower stream of the solvent purified from the acetylenes degasser can be used for indirect heat transfer to the liquid that is extracted from one or more suitable separation stages in the lower combined column region of the column. of extractive distillation heated and / or evaporated and fed back to the extractive distillation column, and / or heat transfer by indirect heat exchange with the cut C4 to be fed to the extractive distillation column. It has been found that the thermal integration in the present process, due to the substantially staggered fall in the heat profile in the extractive distillation column, seen from the lower evaporator through the lower separation stages of the extractive distillation column , it is more favorable compared to the existing processes, especially in comparison with the process of DE-A 103 22 655, especially in approximately 10% compared to said process. In the current process, the special operation mode of the extractive distillation column in which the removal of the C4 acetylenes is carried out in a separate apparatus or part of the apparatus ensures the increased operative reliability, since it is discarded the risk of acetylene accumulation beyond its decomposition limit. Furthermore, the special mode of operation achieves a surprisingly advantageous temperature profile in the partition wall column: even though the lower evaporator of the partition wall column is operated only at slightly reduced temperature compared to the existing process, there is no critical temperature for embedding, that is, no temperature of >is achieved150 ° C in the current process in all the columns, especially also in the dividing wall column and acetylene degasser. In contrast, the temperature in the region in which the acetylenes are degassed is reduced differently, by about 30-40 ° C, compared to the existing process, especially with the consequence that there is therefore significantly less fouling. The invention is illustrated in detail below with reference to a drawing and in a functional example: Figure 1 shows the schematic of a plant of the invention. In a partition wall column TK with a partition wall T in the longitudinal direction of the column, which divides the partition wall column into a first subregion A, a second subregion B and a combined lower column region C, a cut C4 is increased towards the first subregion A. For example, the second subregion B contains 40 theoretical plates and the lower combined column region C contains 10 theoretical plates. The upper stream 2 from sub-region A is passed into the lower region of the extractive upstream washing column K having, for example, 20 theoretical plates. The extractive wash column K is charged with a first solvent undercurrent 3, within the upper region of the same column, and countercurrent extraction occurs, resulting in a lower stream 7 which is conducted within the upper region of the sub-region A of the dividing wall column TK and an upper stream 4 which is condensed in a condenser in the upper part of the extractive washing column K, and a sub-current of the condensate is applied again as stream 5 to the column of extractive washing K and the condensate is otherwise extracted as stream 6. The dividing wall column TK is charged in its second subregion B with a second solvent substream 13. From the second subregion B, an upper stream 14 is extracted and condensed, a substream 15 of the condensed upper stream 14 is introduced as reflux to the second sub-region B of the partition wall column and the condensed upper stream 14 is extracted otherwise as unrefined 1, 3-butadiene (stream 16). From the bottom of the split wall column (TK), the energy is supplied externally to the plant through the lower evaporator (V1> of the dividing wall column (TK).) The proper heat integration within the process it preferably allows the energy to be supplied to the plant externally exclusively at this point, the lower stream 17, solvent charged with the C4 acetylenes, whose content of 1,3-butadiene does not exceed a higher limit whose The loss is economically acceptable, it is preferably after integration of heat with the lower stream from the acetylenes degasser (AG) and more preferably with the liquid being withdrawn from the combined lower column region (C) of the dividing wall column (TK), fed to the acetylenes degasser (AG) in the upper region thereof In the acetylenes degasser (AG), a lower stream 27 which comprises the purified solvent is extracted and, as shown in the figure, preferably after the integration of heat with the liquid which is extracted from the combined lower column region (C) of the partition wall column, and also with the cut C4, it is fed to the dividing wall column, current 1, is recycled inside the process as stream 3 and stream 13. The acetylenes degasser (AG) is joined by a water purifier, in which the solvent residues are washed out of the stream of degassed acetylenes using reflux and fresh water. At the top of the water scrubber (W) a stream 24 comprising acetylenes is extracted, condensed in a condenser at the top of the column, partially applied as reflux to the water scrubber (W) and otherwise discharged from the process as current 26.

Claims (9)

1. A process for obtaining unrefined 1,3-butadiene by extractive distillation with a selective solvent from a C4 cut comprising C4 acetylenes as secondary components in a partition wall column (TK) having a lower evaporator (V1), in which a dividing wall (T) is placed in the longitudinal direction of the column to form a first subregion (A), a second subregion (B) and a combined lower column region (G) and which is placed upstream of an extractive washing column (K), whose process comprises controlling the energy input inside the dividing wall column (TK) through the lower evaporator (V1) in such a way that a lower stream (17) is extracted from the dividing wall column (TK) and comprises solvent charged with the C4 acetylenes whose 1,3-butadiene ratio is restricted so that the loss of 1,3-butadiene is economically acceptable, and feed the lower stream (17) to an acetylenes degasifier (AG) and, in the acetylenes degasser (AG), separate the C4 acetylenes from the top and obtain the purified solvent as the bottom stream (27).

2. The process according to claim 1, characterized in that the ratio of 1,3-butadiene in the lower stream (17) of the partition wall column (TK) is restricted to a maximum from 0.1 to 2 times the proportion of C4 acetylenes.

3. The process according to claim 2, characterized in that the proportion of 1,3-butadiene in the lower stream (17) of the dividing wall column (TK) is restricted to 0.3 times the proportion of C4 acetylenes.

4. The process according to any of claims 1-3, characterized in that the energy of the lower stream (17) of the dividing wall column (TK) is used for indirect thermal exchange with the lower surface (27) of the acetylenes degasser and / or with the liquid which is extracted from one or more separation stages in the lower combined column region C of the dividing wall column, and the separation step from which the liquid is extracted is selected from so much so that the energy demand for the dividing wall column (TK) is minimal.

5. The process according to any of claims 1-4, characterized in that the heat content of the lower stream (27) of the acetylenes degasifier (AG) is used for indirect heat exchange with the liquid that is extracted from one or more separation steps in the lower combined column region (C) of the dividing wall column, and the separation stage (s) from which the liquid is extracted is determined in such a way that energy demand of the dividing wall column (TK) is minimal, and / or that the heat content of the lower stream (27) is used for indirect heat exchange with the cut-off C4 to be separated which is fed to the the dividing wall column (TK). The process according to any of claims 1-5, characterized in that thermally coupled columns are used in place of the partition wall column (TK). 7. The process according to any of claims 1-6, characterized in that - the cut C4 (1) is fed to the first subregion (A) of the dividing wall column (TK), preferably within its region medium, - the upper stream (2) from the first subregion (A) of the dividing wall column (TK) is fed to the extractive wash column (K), within its lower region, - in the column of extractive wash (K), a countercurrent extraction is carried out to load with a first subcorrent (3) of the selective solvent in the upper region of the extractive washing column (K), - the components of the C4 cuts that have less solubility than e? 1, 3-butadiene in the selective solvent are extracted (4) through the upper part of the extractive washing column (K), - the lower stream (7) from the extractive washing column (K) is recycled inside the upper region of the first subregion (A) of the dividing wall column (TK), - a second substream (13) of the selective solvent is fed to the partition wall column (TK) in the upper region of the second subregion (B), - the upper product from the second subregion (B) of the dividing wall column (TK) is extracted as 1,3-butadiene without retinal (16) and - a lower stream (17) consisting of solvent charged with the C4 acetylenes, whose proportion of 1,3-butadiene is restricted so that the loss of 1,3-butadiene is economically acceptable, is extracted from the lower combined column (C) region of the dividing wall column (TK) - the lower stream (17) is fed to the acetylenes degassing (AG) in which the C4 acetylenes are separated by the top and the purified solvent is obtained as the bottom stream (27) and is recycled into the process. 8. The process according to any of claims 1-6, characterized in that the temperature in the lower evaporator (¥ 1) of the dividing wall column (TK) is controlled for a value in the range from 50 to 210 °. C, preferably up to 178 ° G, and the upper pressure of the second subregion (B) of the dividing wall column (TK) for a value from 1 to 10 absolute bars, preferably for a value in the range from 2 to 5 absolute bars, more preferably up to 3.5 bar absolute, and the upper pressure in the acetylenes degasser (AG) up to a value in the range from 1 baria absolute to a maximum of lower pressure in the wall column of division (TK). 9. The process according to any of claims 1-8, characterized in that the acetylenes degasser (AG) is integrated by construction within the lower combined column region (C) by means of configuration of the number of theoretical plates in a lower combined column region (C) for a correspondingly higher value and incorporating a gas-tight division in the dividing wall (TK) column at a point corresponding to the upper end of the acetylene degasser (AG) integrated within the lower combined column region (C). SUMMARY OF THE INVENTION The invention relates to a method for obtaining 1, 3-butadiene not refined by extractive distillation with a selective solvent from a C4 fraction, containing C4-acetylenes as secondary components, in a separation column (TK) With an evaporator lower (¥ 1) within which a gap (T) is placed in the longitudinal direction of the column as it forms a first partial area (A), a second partial area (B) and a lower shared column area (C) , and to which is connected an extractive wash column (K) upstream thereof. The invention is characterized in that the supply of energy within the separation column (TK) through the lower evaporator (V1) is controlled in such a way that a lower flow (17) is extracted outside the separation column (TK) , this lower flow containing solvent loaded with C4-acetylenes whose proportion of 1,3-butadiene is limited in order to make economically acceptable the loss of 1,3-butadiene. The invention is also characterized in that the lower flow (17) is fed to an acetylene degassing device (AG) and, within this acetylene degassing device (AG), the C4-acetylenes are separated by means of! superior and purified solvent obtained in the form of a lower flow (27). 1/1 FIGURE 1