SU1168545A1 - Method of isolating aromatic hydrocarbons from non-condensed gases of styrene production - Google Patents

Abstract

1. METHOD OF THE OWNER , as the high-temperature absorbent used bottom residue rectification of styrene and the absorption is carried out in one step at 40-60 ° C and a pressure of 1-3 atm. 2. A method according to claim 1, characterized in that the desorption is carried out at a BO-BO C and a residual Ci pressure of 20-60 mm Hg Art. (L 9 II S OoEa

Description

eleven

The invention relates to the production of styrene G, in particular, to methods for the separation of aromatic hydrocarbons from uncondensed gases of the process for the production of styrene by the catalytic dehydrogenation of ethylbenzene by absorption with a high-temperature absorbent, and can be used in the petrochemical industry in the production of styrene and other vinyl aromatic hydrocarbons,

The purpose of the invention is to increase the purity of the aromatic hydrocarbons that are in place by reducing their contamination with the components of the absorber of the bent, leading to the pouring of equipment at the stage of ethylbenzene dehydrogenation, as well as reducing the loss of aromatic hydrocarbons.

The drawing shows a schematic diagram of the implementation of the proposed method.

Uncondensed hydrocarbons from the ethylbenzene dehydrogenation department through line 1 enter the absorber 2, where the absorption of aromatic hydrocarbons — benzene, toluene, ethylbenzene, styrene — by the distillation residues of styrene circulating through line 3 by pump 4, then (line 5) to the absorber 2 occurs.

The bottoms of styrene rectification (KORS) used as an absorbent, depending on the instrumentation of the process, the type of catalyst and its mileage, have the following composition, m s.% Styrene 10-35J heavy hydrocarbons with a boil. above 145 C - up to 100, including methyl methyl styrene 2-6 | diphenyl 0.5-1.0; dibenzyl 0.6-1.8, stilbene 1.5-5.4 polymeric products 40-55J unidentified compounds 4-8,

Absorbent — residual distillation of styrene — is saturated with aromatic hydrocarbons from uncondensed (off) gas at 40–60 ° C and 1-3 atm pressure, and part of it enters desorption into a rotary film evaporator 7 heated by water. steam The stripped hydrocarbons are fed via line 8 to condenser 9, from where condensed hydrocarbons are fed to scientific research institute 10 and fed to a collection of hydrocarbons for the dehydrogenation of ethyl 8545 .2

benzene, and an insignificant part of non-condensed hydrocarbons through line 11 enters the fuel network. The bottoms of rectification of 5 styrene (KORS) through line 12 come to collection 13, from where via line 14 by pump 15 and further through line 16 to line 6 of circulation of saturated aromatic hydrocarbons KORS. A portion of the CVS on line 17 is diverted for further processing. On line 18, bottoms distillation of styrene is supplied to line 5 after separation of commodity styrene.

5 The stripping of hydrocarbons in a rotor-film evaporator 7 is carried out under vacuum at 100 ° C and a residual pressure of 20-60 mm Hg. 2 hydrocarbons not absorbed in the absorber,

0 mainly containing hydrogen, methane, carbon dioxide, through line 19 is sent to the refrigerator 20, from which liquid hydrocarbons through line 21 enter the carbohydrate collection

5 kinds of dehydrogenation unit

ethylbenzene, and hydrogen, methane, carbon dioxide, and gas from line 22 are used as fuel on the ethylbenzene dehydrogenation unit or on the side. Example 1 (comparative). The process is conducted by a known method. The aroma from the uncondensed gas is absorbed on two columns. On the first course - ethylbenzene, on the second - polyalkylbenzenes of the composition, wt.%; ethylbenzene - Oj02j methyl ethyl benzene - 0.38 ", diethyl benzene - 13.6 triethyl benzene - 19.6

/ unknown - 12j4, the remainder - 54.

An uncondensed gas containing 1.15% by volume of aromatic gas is fed to the ethylbenzene absorption column.

hydrocarbons - benzene, toluene,

ethylbenzene, styrene. The absorption is carried out at 30 ° C and pressure 3 at. The speed of uncondensed gas in the column at a free cross section of 0.3 m / s. Irrigation density 5 .h. From the ethylbenzene absorption column, the uncondensed gas is sent to the absorption column with polyalkylbenzenes. The rate of uncondensed gas in the column at a free cross section of 0.3 M / s. Absorption is carried out at 30 ° C. Density of irrigation 5. The residual content of aromatics in the uncondensed gas is 0.2 vol.%. The absorbed aromatic hydrocarbons are distilled off from the saturated absorbent on the desorption column at 100 ° C and a pressure of 0.25 atm and condensed. In distilled hydrocarbons, the content of diethylbenzene is 0.015% by weight or 150 ppm. The further processing of condensed aromatic hydrocarbons from diethylbenzene results in the formation of divinylbenzene, which causes an intense clogging of equipment with a crosslinked polymer.

Example 2. The process is conducted according to the proposed method. The separation of aromatic hydrocarbons from uncondensed gas is carried out on a single column. Distillation residues of styrene composition, wt.%: Styrene - 30J heavy hydrocarbons with a bp. above 145 ° C - 70% by weight. Non-condensed gas containing 1.15% by volume of aromatic hydrocarbons - benzene, toluene, ethylbenzene, styrene - is fed to absorption. The absorption is carried out at 40 ° C and a pressure in the column of 1.0 at. Uncondensed gas velocity in the column for a free cross-section of 0.25 m / s Irrigation density 5. After separation, the aromatics content in the uncondensed gas is 0.013% by volume. The present aromatic hydrocarbons from the uncondensed gas absorbent are sent to the desorption on a rotary film evaporator, where at 60 ° C and the residual pressure in the apparatus is 20 mm Hg. absorbed hydrocarbons are distilled off and condensed. In distilled hydrocarbons, diethylbenzene is absent and no crosslinked polymer is formed. The material balance data for the flows are given in Table. one.

Example 3. The process is conducted according to the proposed method. The separation of aromatics from non-condensed gas is carried out on a single column. As an absorbent, slaughter residues of the styro composition are used, wt.%: Styrene - 30} melted hydrocarbons with m, bale. the top 143 ° С - 70 May.7, Uncondensed gas containing 2.5% by volume of aromatic

1685454

hydrocarbons - benzene, toluene, ethylbenzene, styrene.

The absorption is carried out at 50 ° C and the pressure in the column 2 at. The velocity of non-condensed gas in the column for a free section of 0.3 m / s. Absorbent Irrigation Density 5. After insertion, the content of aromatic hydrocarbons in the uncondensed gas is 0.014% by volume. By aromatics from the uncondensed gas, the aromatic hydrocarbon is sent for desorption to the rotary film evaporator,

T5 where at 70s and a residual pressure in the apparatus of 40 mm Hg absorbed hydrocarbons are distilled off and condensed. In distilled hydrocarbons, diethylbenzene is absent and crosslinked

20, no polymer is formed. The material balance data for the flows are given in Table. 2

Example 4. The process is conducted 25 by the proposed method. The extraction of aromatic hydrocarbons from the uncondensed gas is carried out on a single column. As the absorbent is used cubic

2Q residues from the rectification of styrene composition: styrene — 30J heavy hydrocarbons with a bp. more than 70 wt.%. Non-condensed gas containing 4.0 vol.% Of aromatic hydrocarbons — benzene, toluene, ethylbenzene, styrene — is fed to the absorption. The absorption is carried out at a pressure in the column of 3 at. The speed of the uncondensed gas in the column. Is not on the free section of 0.25 m / s. The reflux density of the absorbent is 5 hours. After separation, the content of aromatic hydrocarbons in the uncondensed gas is 0.016% by volume. The absorbent saturated with aromatic hydrocarbons from the uncondensed gas is directed to the desorption on a rotary film evaporator, where at 80 ° C and the residual pressure in the apparatus ::; 60 mm Hg absorbed hydrocarbons are distilled off and condensed. In distilled hydrocarbons, diethylbenzene is absent and no crosslinked polymer is formed.

The material balance data for the flows are given in Table. 3,

Table 1

Note, Note.

Table 2 After separation, the content of the aromatics {in the non-condensed gas is 0.15% by weight (0.013% by volume). After separation, the aromatics content in the uncondensed gas is 0.18% by weight (0.14% by volume). Note. After separation, the aromatics content in the uncondensed gas is 0.2% by weight (0.016% to 6%).

Claims (2)

1. METHOD FOR INTRODUCING AROMATIC HYDROCARBONS FROM UNCONDENSEED GASES FOR PRODUCING STYROL by catalytic dehydrogenation of ethylbenzene by absorption of high hydrocarbons and reduction of their losses. As a high-temperature absorbent, distillation residues of styrene at a pressure of 40 and 60 are used at one and three stages at a pressure of 1–60 and . 2. The method according to π. 1, characterized in that the desorption is carried out at 60-80 C and a residual pressure of 20-60 mm Hg about