DD210398A3 - METHOD OF OBTAINING C LOW 1 / C LOW 2 COMPONENTS AND C LOW 3, - I-C LOW 4 AND N-C LOW 4 FRACTIONS OF HIGH PURITY - Google Patents

Abstract

The invention relates to a distillative process for the recovery of C deep1 / C deep 2 components and C deep3, iC deep4 and n-Ctief4 fractions of high purity from Fluigiggasgemischen.Das goal is a novel linkage of the process units stabilization column, C deep1 / C deep2 Achieved column and C deep3 / C deep4-column, wherein the C deep3 / C deep4-column is coupled with a fractional evaporation stage and / or an isomerization stage. Essential in this technology is the i-C low4 side stream takeoff at the C deep 3 / C deep 4 column.

Description

Method for obtaining CV / Cp components and CU, i-C ^. and high purity n-C ^ fractions

C 07 c 7/04

Field of application of the invention

The invention "relates to a process for obtaining high purity Cj / Cp and C", i C "and N" C "high-activity by distillative separation of" plus "gas mixtures resulting from the processing of hydrocarbon mixtures of primary and reclaimed petroleum refining. for example, in thermal separation processes, such as distillation, condensation, evaporation and deposition, or in processes of thermal or catalytic conversion, such as reforming and aromatization of hydrocarbon mixtures A preferred field of application of the invention is the gas separation plants of the above-mentioned processing stages. ,

Characteristic of the known technical solutions

It is known that column systems of three or more single columns are used in the distillative separation of! Liquid gases which are obtained via a multistage gas compression. , ·. Analog separation systems are used for liquefied gases generated from stabilization stages of reforming and aromatization.

  - 2 - ·

The separation of the Cj / Cp fraction takes place. and the separation of the -Co / CL mixture in a conventional manner in three columns with top product-bottoms separation, wherein the columns are each technologically coupled via the bottom products. ,

Figure 1 shows a conventional workup of liquid reaction products of: thermal and catalytic hydrocarbon conversion stages (reformers, aromatizer cracking units, etc.). In this case, the unstabilized liquid reaction product 8 is prestabilized together with the expansion gas 12 in the separation vessel 1, heating gas being fed to the stabilization column 2 via the top and the liquid product to be stabilized. As the bottom product of 2, the stabilized liquid product 15 is withdrawn. The. Top product vapors 11 pass via the condenser 3 into the overhead product template 4. The liquid product from 4 passes partly as reflux to the stabilization column 2 and to the C 1 / C p column 5. Here, the head-sump separations take place into a C ₁ ZC ₂ fraction 16 and a Co / C ^ fraction 17, which is fed to the Ct / C, column 6, wherein a co-Prak- tion as top product 18 and a C, fraction 19 are recovered as the bottom product.

Der.Strom 19 can be discharged as required in C ^ -Praction 20 or used as feedstock 21 to ΐ-ΰκ / η-Ο, column 7. In this case, a separation into an iC takes place in this column. Fraction 22 as the top product and a η -C J ₁ fraction 23 as bottoms product. According to DE-OS 2413463, a G-emisch consisting of C ^ and ^ hydrocarbons in a C ^ and C ^ _ Fraktion.aufgetrennt, wherein the mixture in

- 3 -

precursor of a first column and the resulting bottom product is further distilled in a second column, with compression and recycling of the top product of the second column.

DS-OS 2330374 describes a process which is particularly suitable for use in depropanizing fractionation using a high pressure fractionating tower C and a leaching tower reboiling pressure stage.

By appropriate choice of pressure and temperature, the optimum conditions for vaporizing the hydrocarbons, and condensing the vapors can be easily adjusted.

In DD-WP 25571 a device for the separation of n-C ^ _ from Alkylatgemischen is described as a side fraction of C. Tr.ennkolonne. In this case, the C ^, - column is divided into two by a modified Glockenboden.für the liquid phase. The heat transfer remains through the. Connection secured via the Eampfstrom for the entire column. ,

In the hitherto known technical solutions, a high expenditure on equipment and energy is necessary. Due to the number of columns used and the special design of special constructions. Furthermore, the realization of such separation processes takes place under unfavorable hydrodynamic, separation-technical and energetic process conditions and their non-effective use. "

With regard to the quality requirements for the target products G ₁ ZG ₂ -JC ₃ , i-όκ- ,. nC ^ T fractions have a low flexibility.

L ° t \ IUU

Aim of, invention .

The aim of the invention is "to disassemble liquid gas mixtures by distillation with high flexibility with respect to product qualities into Cj / Cg-CU-iC ^ and η-Cl fractions with little expenditure on equipment and at the same time reducing the operating costs They are used as Yerkaufsprodukte or as products for technological processing, such as the C ^ / G ₂ fraction as heating gas or additive component for water purification systems and the iC ^ / nC ^ fraction as an input product for alkylation processes.

Explanation of the essence of the invention

The object of the invention is to provide a simple technological solution for obtaining C 1 / Cp-CU-i-C. and to find n-Cn fractions by distillative separation of liquefied petroleum gas mixed thermal separation or thermal or catalytic conversion.

Starting from the known prior art, the recovery of the C ^ / Cp-Co-iC ^ and. η-Cl fractions in a three-column system,. Consisting of a stabilization column, a C ^ / p and a Co / Cl column. By a novel linkage of the process units takes place according to the invention the recovery of Cwp-C ^ -iC ,, and η-C ,, - fractions such, that first the Ci / C, -rich top fraction of the stabilization column of the d / C ^ column is supplied , wherein C, -rich side stream of the stabilization column in the Sumpfseküon the

P column and / or in the sub-column of the Co / C column can be fed. The vapor fraction from the top product template of the stabilization column passes into a post-condensation stage for decomposition into a liquid co-reiclie fraction and a C ^ / C ₂ -rich fraction. Corresponding to the C 1 content, the C, C section is fed directly to the top section of the CU / C 2 column with or without the inclusion of a C, rich intermediate fraction from the top section of the C 1 / Cp column, or to the top section the C ^ / Cp column given. Depending on the required selectivity between iC ^ and nC, the C ^ -mixture as Sumpfprodukt.der C ^ / Cp column or pre-separated as iC.-rich intermediate fraction of the C ^ / Cp column and the η-C ^ - rich bottoms fraction fed separately to the Co / C, column. Here C ^ are obtained as the top product, a nC ^ rich fraction as the bottom product and an iC ^ -rich side fraction. To obtain nC. and iC, fractions of high purity, the bottom product of the Co / C, column is then fed in whole or in part to a Uachverdampfungsstufe, wherein the resulting, steam-rich iG ^ -rich fraction below the iC, -Aufnahme in the CU / C, column is fed and a liquid product with high η-C, content is obtained and / or the nC, -rich bottom product of the CU / C ^ column and / or the liquid product from the Hachverdampfer partially or completely in a nC, Isomerisierungsstufe used and the resulting iC ^ -rich isomerate in the sump sekt ion of 0 -, / Cl-column is recycled. Yields for the target products C- ,, iC /, are at ^ 70 113 ..-%.

ο -

- 6 embodiments

example 1

With reference to Figure 2, the recovery of Cj / Cp, C ^, i-C, and η-C, fractions from the liquid reaction products of reforming and aromatization, processes are explained in more detail. , ..

The separation of the liquefied gas mixtures takes place as gaseous and / or liquid top product 27, 14 with or without C. side fraction 31. the top column of the stabilization column.

The expansion gas 27 from the. Top product template 4 of the stabilization column 2 is condensed in a condenser 24. and separated into a vaporous C ^ / Cp fraction 28 and C. Rich liquid fraction, which is a partial stream 29 to the top column der.CL/Cp- column 5. and / or as a partial stream 30 directly into the upper column of

6 is led.

The C, side fraction 31 from the stabilization column is, depending on the 0,. / Cp or nC, content optionally as a partial stream 32 in the bottom section of the 0 ^ / C ₂ column 5 and / or as a partial stream 33 and 34 in the sub column of C-VC ^ -Konne 6.eingeleitet. From the top section of the C ^ / Cp column 5, the C, / Cp fraction: 16 are withdrawn as top product and a · Co side fraction 35, the stream 35; in the head section of the Co / C.-column 6 is driven. According to the iC, distribution in the C ^ / Cp column '5 an iC \ side fraction 36 is led to the column 6 from the lower or upper column. The bottoms product: 37 passes without or with partial flow 33 to the sub-column of C at the top of the C ^ / C ^ column 6 is obtained via line 18 as Köpfprodukt.

- 7 -

According to the CU and i-C ^ distribution, an i-C. side fraction from 6 is withdrawn from the upper column / sub-column, the removal product being gaseous or liquid (see Example 2, Pig.

From the bottom of the C ^ / C ^ column an nC ^ - rich bottom product 40 is withdrawn, wherein the partial stream 23 is discharged and another partial stream optionally with or without I ¹ Ussigfraktion 41 from the (_, bottom heating 26 to Eest iC. reconditioning is supplied to the reboiler 25, wherein the iC ^ - enriched vapor stream 43 is returned to the sump section of the Co / C, -Kolonne 6 the liquid product of the 'reboiler 25 is obtained as nC.-rich fraction ^42;.....

Example 2 '-' With reference to Figure 3, a preferred solution for the reconstruction of existing plants with conventional technology is described, which only on the C ^ -C, -. Separation refers.

Similarly, this Yariantenlösung is in the design of C - ^ - Ck -Trennprozesses in execution ^v 'Example 1 (see Fig. 2.) Are applicable.

The CU-Cr separation process is carried out in a split column or a combination of two columns with the top 6a and the bottom 6b at high Trennstuf en number.

, Particularly effectively, the removal of the i-C ^ side fraction can be designed by liquid or vapor withdrawals 38a / 38b are provided in the 3ereich the apparatus coupling 6a / 6b. For effective i-C ^ extraction is an additional

L ¹ HULU ö

-B-

n-C.-isomerization step. 48 used in the

n-C, -rich current 47 is used, which is

partially or completely composed of the partial streams 41, 44, 45 and 46.

The i * C, -rich isomerate 49 becomes the bottom section

supplied by 6 "b.

With this method, it is possible to make the i-C./n-C.Yerverhältnis for further processing, preferably in alkylation and cheap

to influence. .

List of used reference signs

1 separating container

2 stabilization column

3 sondenator of 2

4 overhead product template of

5 C ₁ / C ₂ column

6 CU / C \ column with split design 6a - upper part.

6b lower part.

C7 i-C, / n-C. column

8 Unstabilized Liquid Sifting Product

9 heating gas from 1 (Cj / C ₂ fraction)

10 use rate.to 2

11 head steam from 2.

12 relaxation gas from 4

13 return for 2

14 feedstock of 5

15 bottoms product of 2 '

16 Ca / C ^ as top product of:. ' 17 feedstock for 6

18 .. C ο fraction as a head product of

, - .19 sump product of 6

• 20 i-n-Cκ fraction - ejection off

21 feed product for 7

22 i-G, fraction as top product of

23 n-C ^ -raction as the bottom product of

24 Uachkondensator for 27 after

25 Kachverdampfer> for 44 u./o.

26 sump heating of 6

27 relax gas out

28 heating gas after 24

29 condensate from 24 too

ΊΟ - t -

30 condensate from 24 to 6

31 Cu side fraction from 2

32 partial flow from 31 to 5

33 partial flow from 31 to 37 after

34 partial flow from 31 to

35 C, - side fraction from 5

36 i-C. side fraction from 5

37 bottoms product from 5 '

38 i-Cr side fraction from 6 / "to 6a, Td occurs

Optionally, the i-C ^ liquid fraction 38a can be taken via the

: lines 38a

- The i-C.-Favffraktions-38b removal either over

the lines 38b

39 partial flow from 38 to 23

40 bottom product of 6

"41 Plüssigfraktion from 26

42 η-C ^ fraction after 25 "

43 steam st romre cycle off 25.

44 partial flow from 40 to 25

45 Plüssigfraktion from 25

46 partial flow of 41 u./o. 44 for n-C ^ isomerization or leaching

47 Feedstock for n-C, isomerization

48 n-Cκ isomerization

49 isomerizate from 48 to 6b

Claims (1)

Claim for invention A process for the recovery of Cj / Cp components and Co, iC, and η-C ^ fractions of high E unit by distillative separation of Flüssiggasgemischeη the thermal mass separation or the thermal or catalytic conversion in a three-column system consisting of a stabilization column, a C ^ / Cp- and a Co / C. Eolonne characterized in that the C -, / C ^ -rich top. Fraktion the stabilization column of C./Cp- column is supplied with or without feed of a C. richη Side stream of the stabilization column in the bottom section of the C./Cp column and / or the sub column of the C -, / C ^ column; the vapor fraction from the top product template of the stabilization column in a Hachkondensationsstufε into a liquid coreiche fraction and a C,. / C ₂ -rich fraction is decomposed, wherein according to the C ^ content of the co-cut directly the head section of C ^ / C. ^ -Column with or without involvement of a C ^ -rich intermediate fraction from the top of the section of the C ^ / Cp column or fed to the head section of the Cj / C ^ column is given and depending on the required selectivity between iC ^, and nC, ^^ _n _.,, - _n as the bottom product of the Ci / Cp column or pre-separated as i-Cκ-rich. Intermediate fraction of the C ^ / Cp column and the nC.-rich bottoms fraction, are fed separately to the C / C column and C-> as pigtail product with purities of ^ - 70 Ma .- $, an nC, - rich fraction can be obtained as bottoms product and an iC-rich side fraction where "the bottom product of the C 1 / C 2 column is completely or partially fed to a post-evaporation stage and the resulting vaporous iC-rich fraction is maintained) of the iC, -Attachment in the C ^ / C, column fed and from the ÜTachverdampfer a Plüssigprodukt with nC, contents - 70 Ma .- ^ -Tommen is and / or the nC, -rich bottom product of Co / C, column and / or the liquid product from the vapor it partially "or used completely in a nC ^ Isomerisierungsstufe and the resulting iG, -rich isomerate in the bottom section of the Co / C, column to increase the iC, content to - 70 Ma. S is returned. for the pages of the Zetdinungen