Crude 1,3-butadiene processing method

FIELD: petrochemical processes.

SUBSTANCE: hydrocarbon mixture obtained by extractive distillation of C4-fraction using selective solvent, which mixture contains those C4-hydrocarbons, which are better soluble in selective solvent than butanes and butenes, is subjected to continuous separation. Mixture is supplied to first distillation column, wherein it is separated into top stream, containing 1,3-butadiene, propine, and, if necessary, other low-boiling components and, if necessary, water, and bottom stream containing 1,3-butadiene, 1,2-butadiene, acetylenes, and, if necessary, other high-boiling components. Proportion of 1,3-butadiene in bottom stream of the first distillation column is controlled in such a way as to be high enough to dilute acetylenes beyond the range wherein acetylenes can spontaneously decompose. Top stream from the first distillation column is passed to second distillation column, wherein it is separated into top stream, containing propine, and, if necessary, other low-boiling components and, if necessary, water, and bottom stream containing pure 1,3-butadiene.

EFFECT: simplified process and reduced power consumption.

4 cl

 

The present invention relates to a method for processing a mixture of hydrocarbons, which was obtained by extractive distillation C4-faction.

The term "C4-fraction denotes a mixture of hydrocarbons having predominantly four carbon atoms in the molecule. With4-faction receive, for example, in the production of ethylene and/or propylene by thermal cracking, usually in steam crackers or FCC-units (FCC - fluid catalytic cracking of petroleum fractions, such as liquefied petroleum gas, gasoline or gas oil. With4-faction also obtained when the catalytic dehydrogenation of n-butane and/or n-butene. C4-fractions usually contain butane, n-butene, isobutene, 1,3-butadiene together with small amounts of other hydrocarbons, including the butins, in particular 1-Butin (ETHYLACETYLENE) and Butenin (vinylacetylene). The content of 1,3-butadiene in C4the fractions from steam cracking units is usually 10-80 wt.%, preferably 20-70 wt.%, in particular 30-60 wt.%, while the content of vinylacetylene and ETHYLACETYLENE usually does not exceed 5 wt.%.

Division With4-factions is a complex distillation problem, due to small differences in the relative volatilities of the components. Therefore, the division performed by extractive distillation, i.e. distillate the th with the addition of a selective solvent (also referred to as extracting agent), which has a boiling point higher than the boiling point of the mixture, which is subject to separation, and increases the difference in relative volatility of the components, which are subjected to the separation.

There are many ways of separation4-fractions by extractive distillation using a selective solvent. Common to all these methods is that gaseous4-fraction, which is subjected to the division lead in countercurrent contact with a liquid selective solvent in a suitable thermodynamic conditions, usually at low temperatures, often in the range of 20-80°With, at moderate pressure, often at atmospheric pressure up to 6 bar, so that the selective solvent load components4-faction, to which it has a relatively high affinity, while the components to which the selective solvent has a lower affinity, remain in the gas phase and are removed through the top of the column. Then one or more subsequent stages of the process fractional components are removed from a stream containing solvent, in a suitable thermodynamic conditions, i.e. at elevated temperature and/or reduced pressure compared to the first stage of the process.

Extractive distillation With4fractions are often held in such a way that components4fractions, to which the selective solvent has a lower affinity than to 1,3-butadiene, in particular butane and butenes, remain essentially in the gas phase, while 1,3-butadiene and other hydrocarbons to which the selective solvent has a higher affinity than to 1,3-butadiene, and essentially completely absorbed by selective solvent. The gas phase is removed through the top of the column and is often referred to as raffinate 1. Such a process is described for example in DE-A 19818810, where the raffinate 1 is a flow indicated as the Gbc, which is removed through the top of the column extractive distillation E I figure 1 and 2.

Processing loaded 1,3-butadiene and other hydrocarbons, for which the selective solvent has a higher affinity than for 1,3-butadiene-selective solvent is typically fractionated by desorption, and absorbed in the selective solvent hydrocarbons desorbers in the reverse order of their affinity to selective solvent.

Such a method is known for example from DE-A 19818810, according to which the selective solvent, loaded with 1,3-butadiene and other4-hydrocarbons and referred to as so-called extraction solution ad, translated at the stage of method 3 in the desorption zone with reduced relative the structure to the zone of extraction pressure and/or elevated temperature and at the same time of the extraction solution ad desorbed 1,3-butadiene, most of the area With4-hydrocarbon remains in the liquid phase. When it discharged two separate threads, namely 1,3-butadiene as a raw stream of 1,3-butadiene and other loaded With4-hydrocarbon-selective solvent as the extraction solution d. From the extraction solution d in the second zone desorption low in relation to the first zone desorption pressure and/or elevated temperature and pressure gradient and/or temperature fraktsionirovannoe desorbers remaining 1,3-butadiene and other4-hydrocarbons, at least, as two separate factions.

According to the present opinion has so far been impossible to separate by distillation acetylene and 1,2-butadiene from crude 1,3-butadiene with an economically acceptable cost. Particularly problematic was little difference in the relative volatility and high reactivity forming a stream of crude 1,3-butadiene component.

Therefore, the present invention is to develop a method that is acceptable economic costs provides the distillation separation of acetylenes and 1,2-butadiene from a stream of crude 1,3-butadiene and at the same time provides a reliable way. The method according to the invention allows the distillation processing flows of crude 1,3-is utadiene without the preliminary stages of a complex branch of acetylenes by extractive distillation using a selective solvent.

The problem is solved as a continuous method of separating a mixture of hydrocarbons, which was obtained by extractive distillation With4-fractions using the selective solvent and which includes hydrocarbons from C4-fractions, which are more soluble in the selective solvent than butanes and butenes, which differs in that the mixture fed to the first distillation column where it is separated into the head stream comprising 1,3-butadiene, propyne, if necessary, other low-boiling components and, if necessary, water and a bottom stream comprising 1,3-butadiene, 1,2-butadiene, acetylene, and, if necessary, other high-boiling components, and the proportion of 1,3-butadiene in the bottom stream of the distillation column is adjusted so that it at least so high that it dilutes acetylene outside the zone of danger of spontaneous decomposition and the main stream of the first distillation column serves to the second distillation column and the second distillation column is divided into the head stream, including propyne, if necessary, other high-boiling components and, if necessary, the water and the bottom stream comprising purified 1,3-butadiene.

Thus, according to the invention the flow of crude 1,3-butadiene is subjected to fuzzy adopt the Oia to 1,3-butadiene distillation separation in the distillation column, acetylene and 1,2-butadiene removed as a bottom stream that is diluted with 1,3-butadiene outside the zone of danger of spontaneous decomposition. However butadiene, together with propyne, if necessary, with other low-boiling components and, if necessary, with water diverted as the head of the stream.

The head stream of the distillation column preferably condense in the condenser in the upper part of the column, a portion of the condensate returned to the column, and the remainder served in the second distillation column in which they are divided into the head stream containing propyne and possibly other low-boiling compounds, and the bottom stream containing pure 1,3-butadiene.

In both the above distillation columns, in principle, you can use all internal separation elements, typically used for distillation of butadiene. Due to reduced fouling tendency is especially suitable are the plates.

The composition of the stream of crude 1,3-butadiene depends on the composition of4-faction, which was filed on extractive distillation, and includes, as a rule, all acetylene, the entire 1,2-butadiene, from 30 to 70% CIS-2-butene and at least 99% 1,3-butadiene from C4-faction.

More low-boiling than 1,3-butadiene, hydrocarbons are referred to as low-boiling components and more Wysocki Asia, than 1,3-BUTADIENES, hydrocarbons are referred to as high-boiling components. Typical low-boiling component is propyne, high-boiling components are hydrocarbons with a triple bond, hereinafter referred to as acetylene, in particular 1-Butin (ETHYLACETYLENE) and Butenin (vinylacetylene).

The term "if necessary"used in this description in the context of the composition of the flows obtained in the processing of distillation, means that the components described thus may be present in the relevant threads, depending on the specific process conditions, in particular depending on the composition used With the4-faction used solvent and/or auxiliary substances.

Department of acetylenes and 1,2-butadiene from crude 1,3-butadiene by distillation is a complex problem due to their high reactivity and small differences in the relative volatilities of the components that make up the flow of crude 1,3-butadiene. However, it has been unexpectedly discovered that acetylene and 1,2-butadiene can be separated by distillation with acceptable power consumption and at the same time, the process reliability can be achieved if acetylene and 1,2-butadiene assign as the bottom stream from the distillation column and, thus, they rasb Vlada 1,3-butadiene for outside the interval, where there is a risk of spontaneous decomposition. For this purpose usually is sufficient thinning of the lower thread to values below 30 mol.% acetylenes. With4-faction, as a rule, have the composition of the next interval wt.%:

1,3-butadienefrom 10 to 80
butanefrom 10 to 60
the butenesfrom 5 to 40
other4-hydrocarbons andfrom 0.1 to 5
other hydrocarbons, in particular
With3- and5-hydrocarbonsfrom 0 to maximum 5

The designation "pure 1,3-butadiene" refers to the stream with the content of at least 99 wt.% 1,3-butadiene, preferably, at least a 99.6 wt.% 1,3-butadiene, balance impurities, in particular 1,2-butadiene and CIS-2-butene.

In a preferred process variant, the bottom stream from the first distillation column and head stream from the second distillation column is fed to the reaction column distillation, which is carried out heterogeneously catalyzed selective hydrogenation of hydrogen to hydrocarbons containing a triple bond, to hydrocarbons containing a double bond, to receive a top stream containing 1,3-butadiene, butanes, butenes and stop the TCI negidrirovannah hydrocarbons, having a triple bond, and a bottom stream containing high-boiling compounds, which divert.

In particular, vinylacetylene selectively hydronaut to useful product of 1,3-butadiene.

Head stream from the column reactive distillation or partial stream is preferably recycled to the extractive column distillation. However, it is also possible to select the stream from the upper part of the column reactive distillation or a substream of the installation and to process it further, for example, in the cracking installation or burn it.

A preferred variant of the method with selective hydrogenation of the lower flow acetylenes in extractive distillation has technological advantages, in particular in relation to the possible selection of the catalyst, since the selective hydrogenation is conducted at the stage of processing, which is actually in the reaction mixture there was no selective solvent. If, on the other hand, selective hydrogenation would be held, as in the known method, in the column extractive distillation and, thus, in the presence of a selective solvent, the choice of catalyst would be significantly limited by selective solvent that could do hydrogenation of the less selective. In contrast, selective hydrogenation of the lower thread at extractiv the second distillation not subject to restrictions regarding the choice of catalyst.

The invention is illustrated further by means of the schema and example execution.

The figure schematically shows an installation for the distillation separation of the stream of crude 1,3-butadiene.

The flow of crude 1,3-butadiene, denoted as4H6served in the first distillation column K I, where it is divided into the head stream K I-K and the bottom stream K I-s Head-flow K I-K condense in the condenser K in the upper part of the column, a portion of the condensate returned to the column, and the residue away and sent to the second distillation column K II. The bottom stream K I-S assign and served in the column reactive distillation each of the three RDK.

In the second distillation column K II condensate from the first distillation column is shared with getting the head thread To II-K, which condense in the condenser K, part of the condensate return in the form of reverse flow in the column, and the residue is similarly sent to the column reactive distillation each of the three RDK. The bottom stream K II-S from the second distillation column II To divert the flow of pure 1,3-butadiene.

In the column reactive distillation each of the three RDK hydrocarbons containing a triple bond, selectively hydronaut hydrogen to hydrocarbons containing a double bond, in the presence of a heterogeneous catalyst. Head flow each of the three RDK-K assign, condense in the condenser To a portion of the condensate returned to the column p is a promotional distillation of each of the three RDK, and the rest, as shown in the drawing, mostly recycle to the column extractive distillation.

The bottom stream from the column reactive distillation, namely the flow of each of the three RDK-S, which contains mainly high-boiling components, away from the installation and mainly burn.

Example: distillation refining of crude 1,3-butadiene

The flow of crude 1,3-butadiene With4H6that is obtained by extractive distillation from C4-faction, led to the distillation column with 80 theoretical plates at 25 a plate, when calculating the plates from the bottom up. The flow of crude 1,3-butadiene With4H6had the following composition, wt.%:

propyne0,11
1,3-butadiene98,58
1,2-butadiene0,30
1-butyn0,30
vinylacetylene0,56
water0,15

Separated in the first distillation column K I on head flow K I-K with the following composition, wt.%:

propyne0,11
1,3-butadiene99,73
water0,16

and on the bottom stream K I-S with the following composition, wt.%:

CIS-butene-20,52
1,3-butadiene40,0
1,2-butadiene15,1
1-butynof 13.75
vinylacetylene29,17
3-methylbutan-10,98
2-methylbutan-20,48

Head flow K I-K first distillation column K I share on allotment (1/7 head flow K I-K) and recycling (6/7 head flow K I-K). The outlet serves to the second distillation column K II with 25 theoretical plates, 14-th separator plate and divided into head-flow K II-K with the following composition, wt.%:

propyne79,52
1,3-butadiene20,0
water0,48

and on the bottom stream K II-S, including pure 1,3-butadiene content of 1,3-butadiene to 99.99%. The bottom product K II-S to divert as useful product.

In comparison with the known method of obtaining 1,3-butadiene from C4-faction with the Department of acetylenes from 1,3-butadiene by extractive distillation with a selective solvent in the present method achieves energy savings of about 9%. In addition, the installation due to the elimination of columns for the separation of acetylenes from 1,3-butadiene extrac the active distillation is simplified and reduced the cost of investment and saving floor space.

1. Method for continuous separation of mixtures of hydrocarbons obtained by extractive distillation With4-factions (C4) using the selective solvent, which includes hydrocarbons from C4-factions (C4), which are more soluble in the selective solvent than butanes and butenes, characterized in that the mixture fed to the first distillation column where it is separated into the head stream comprising 1,3-butadiene, propyne, if necessary, other low-boiling components and, if necessary, water, and a bottom stream containing 1,3-butadiene, 1,2-butadiene, acetylene and, if necessary, other high-boiling components, with a ratio of 1,3-butadiene in the bottom stream from the first distillation column, a regulated so that it was high enough for cultivation acetylenes to outside the interval in which there is a risk of spontaneous decomposition, and the main stream from the first distillation column serves the second distillation column and divided into the head stream containing propyne, if necessary, other low-boiling components and, if necessary, water, and a bottom stream containing pure 1,3-butadiene.

2. The method according to claim 1, characterized in that the proportion of 1,3-butadiene in the lower stream of the first distillation column in the bran thus, the share of acetylenes in the lower stream is less than 30 mol.%.

3. The method according to claim 1, characterized in that the bottom stream from the first distillation column and head stream from the second distillation column is fed to the reaction column distillation, which is carried out heterogeneously catalyzed selective hydrogenation of hydrogen to hydrocarbons containing a triple bond, to hydrocarbons containing a double bond, with partial conversion of acetylenes, getting a head stream containing 1,3-butadiene, butanes, butenes and digidrirovannye hydrocarbons that have a triple bond, and a bottom stream containing high-boiling compounds, which divert.

4. The method according to one of claims 1 to 3, characterized in that the head stream from the reactive distillation column or partial recycle stream by extractive distillation.



 

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2 cl, 1 dwg, 6 ex

FIELD: chemical technology, in particular method for vinylchloride production.

SUBSTANCE: claimed method includes fast gas cooling in quenching column followed by separation of pyrolysis products. Quenching and separation are carried out by barbotage through the layer of liquid concentrated by-products of these gases in quenching column cube. Then steam/gas mixture is brought into contact with returning condensate in regular filling layer of rectification tower with simultaneous purification of steam/gas mixture in rectification zone upstream. Liquid concentrated by-products are additionally rectified in vacuum with isolating and recovery of products having boiling point higher than the same for dichloroethane and distillate recycling. Method of present invention also makes it possible to produce perchloroethylene and tricloroethylene.

EFFECT: vinylchloride of high quality; reduced effort and energy consumption.

2 tbl, 4 dwg, 2 ex

FIELD: petroleum chemistry, chemical technology.

SUBSTANCE: fractionation is carried out in two columns. The parent raw is fed on the second column top, in line of its phlegm and isoprene fraction is removed from the second column top and fed its to the first column. Piperylene fraction is removed from the second column vat and isoprene is removed from the first column top, and isoprene-amylene faction is removed from this column vat that is fed for extractive fractionation. Invention provides reducing energy consumptions, enhancing quality of separation products and reducing their losses.

EFFECT: improved separating method.

2 dwg, 6 tbl

The invention relates to techniques for the separation of multicomponent mixtures of substances on individual substances or fractions, namely, a distillation apparatus for separating bizcochada mixtures of higher aliphatic acids of number four fractions

FIELD: petroleum processing.

SUBSTANCE: separation of crude C4-fraction comprises rectification of C4-fraction containing butanes, butenes, 1,3-butadiene, and small amounts of other hydrocarbons, including C4-acetylenes, 1,2-butadiene, and C5-hydrocarbons, via extractive distillation using selective solvent. Crude C4-fraction is fed to middle part of first extractive distillation column and selective solvent is added to column above crude C4-fraction introduction point. Vaporous side stream containing C4-acetylenes together with 1,3-butadiene1,2-butadiene, C5-hydrocarbons, and selective solvent, wherein concentration of C4-acetylenes is below self-decomposition threshold, is withdrawn from the first distillation column from the point below crude C4-fraction introduction point. Top stream containing crude C4-fraction components, which are less soluble in selective solvent than C4-acetylenes, are withdrawn from upper part of the first extractive distillation column.

EFFECT: optimized order of process operations.

21 cl, 1 dwg

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