The method of obtaining hydrocarbon vinylaromatic

 

(57) Abstract:

The invention relates to the production of vinylaromatic hydrocarbons, such as styrene, alfamethylstyrene, divinylbenzene, etc. and can be used in the petrochemical industry. In the method of obtaining vinylaromatic hydrocarbons by catalytic dehydrogenation of alkylaromatic hydrocarbons in multi-stage reactor in the presence of water vapor under vacuum evaporation and overheating alkylaromatic hydrocarbon is carried out under vacuum to 0.8-0.9 ATA mixed with purified steam condensate in the ratio of 1: 0.3 weight or in a mixture alkylaromatic hydrocarbon, purified steam condensate, water vapor in the ratio of 1:0,2:0,1 weight, which is heated by the heat of the steam condensate, circulating in the foam apparatus, evaporation and initial overheating due to the indirect contact with a mixture of water vapor, coming from the waste heat boilers and interstage superheater gas contact and the final overheating is due to the heat contact of the gas after the last stage of dehydrogenation. The technical result - the reduction in specific steam consumption for evaporation and overheating alkylaromatic from the I to the production of vinylaromatic hydrocarbons, for example, styrene, alphamethyl-styrene, divinylbenzene, etc. and can be used in the petrochemical industry.

There are various ways dehydrogenation of alkylaromatic hydrocarbons in multi-stage reactor in the presence of water vapor on iron oxide catalysts.

Raw materials - alkylaromatic hydrocarbon fed to the dehydrogenation, is evaporated by direct and indirect contact with steam, superheated and then combined with the principal amount of steam to steam: the raw material is 1:1.5 to 3.0, and passes the system of reactors.

Contact the gas is cooled in waste heat boilers and foam apparatus, and then is condensed with obtaining fractions of hydrocarbons and water.

The disadvantage of these methods is the increased consumption of water vapour evaporation of alkylaromatic hydrocarbons.

A known method of producing styrene (U.S. Pat. USA 4628136, 1986), in which the dehydrogenation of ethylbenzene is carried out at a pressure close to atmospheric, whereby the source of the benzene is evaporated due to the heat of the water vapor from the network or due to the heat of distillate column selection benzene return.

The disadvantage catarineu work of the whole production.

Also known is a method of obtaining vinylaromatic hydrocarbon (RF patent N 212043, 1997), whereby the evaporation of alkylaromatic hydrocarbons is due to the heat of the water vapor by direct or indirect contact with the mixture supply source of the hydrocarbon with steam in a different stage of the process.

The method allows to reduce the specific consumption of water vapor and the formation of high-boiling products, but also has the disadvantages indicated above.

The closest in technical essence is a method of producing styrene, according to which the dehydrogenation of ethylbenzene is carried out under vacuum and the evaporation of benzene occurs under excess pressure through direct and indirect contact with steam from the network, and overheating due to the heat contact of the gas after the second stage. (U.S. Pat. USA N 3702346, 1972).

The disadvantage of this method is the increased consumption of water vapor by evaporation of the benzene and the increased output of high-boiling by-products.

The aim of the invention is the reduction of specific consumption of steam and the formation of high-boiling by-products.

This goal is achieved by the described way the floor is a multi-stage reactor at an elevated temperature in the presence of water vapor under vacuum, at which evaporation and overheating alkylaromatic hydrocarbon is carried out under vacuum to 0.8-0.9 ATA mixed with purified steam condensate in the ratio of 1:0.3 weight or in a mixture alkylaromatic hydrocarbon, purified steam condensate, water vapor in the ratio of 1:0,2:0,1 weight, first by heating the heat of the steam condensate, circulating in the foam apparatus, then through indirect contact with a mixture of water vapor coming from the waste heat boilers and interstage superheater gas contact, and the final overheating due to the heat contact of the gas after the last stage of dehydrogenation.

The drawing shows a scheme for vinylaromatic hydrocarbon is styrene, explaining the proposed method.

Water Nar from the network, the incoming line 1, is mixed with steam entering through line 27 from the HRSG 26, and is sent by means of line 3 in the first section of the superheater furnace 4, where line 5 is fed to the interstage superheater reactor unit 6, and then in line 7 returns the second section of the superheater furnace.

Part of the water vapor from the interstage superheater 6 through line 8 is combined with a part of the pair, postuplenii 10 is returned in line 7 and then to superheat furnace.

Ethylbenzene enters the heat exchanger 12 through line 11, where it is heated steam condensate to a temperature of 85oC coming on line 13 from the circulating line foam device 14. Then the benzene is combined with the purified steam condensate from the apparatus 15 in the ratio of 1:0.3 or with steam condensate and steam in a ratio of 1:0,2:0,1 (steam flow is shown by the dotted line) and line 16 is directed to the evaporation in the evaporator 9, a heated mixture of water vapor coming from the waste heat boilers 26 and interstage superheater 6.

The vaporized ethylbenzene but line 17 is sent to the superheater ethylbenzene 18, where it is superheated by the heat contact of the gas coming from the reactor 23 through line 24. From the superheater 18 ethylbenzene with a temperature of 550oC on line 27 is supplied to the Association with a major amount of water vapor in the ratio of steam:ethylbenzene 1:1.5 to 3.0, and passes through the first and second stage dehydrogenation reactor 19, 23.

Contact the gas discharged from the last stage of the reactor, gives its heat to the first superheater 18, where it flows through line 24, then line 25 in waste heat boilers 26 and finally into the foam apparatus 14 and is supplied to the node condena vacuum compressor, and the condensed portion is separated into a hydrocarbon portion and steam condensate, but the line 31 is returned to the circulation in the foam unit 14. Excess steam condensate but the line 13 through the heat exchanger 12 is fed to a purification unit 15 and partially served on the evaporator 9, and partly in the HRSG 26 (not shown in the figure).

The hydrocarbon part of the "heating" oil is directed to the rectification line 32 to obtain vinylaromatic hydrocarbon.

Example 1 (the prototype)

Dehydrogenation of ethylbenzene to styrene is carried out in a two-stage reactor for iron oxide catalyst under vacuum of 0.6-0.7 ATA at a temperature of 580-630oC depending on the lifetime of the catalyst with reheat contact of the gas with water vapor from the superheater furnace with subsequent return of this pair in the oven and then to the first stage dehydrogenation.

The dehydrogenation is ethylbenzene fraction composition: ethylbenzene 98 wt.%, benzene 0.2 wt.%, toluene 0.3 wt.%, styrene and 1.5 wt.%.

Ethylbenzene fraction is mixed with steam in a ratio of 1:0.3 weight and enters the evaporator where it is evaporated under a pressure of 1.5 ATA also due to the heat vadana due to the heat of the contact strip, emerging from the second stage reactor, after it with a temperature of 550oC routed to the first stage dehydrogenation.

For evaporation and overheating of etilbenzene faction in the number of 1.76 ton/tons of styrene spent 0,99 Gcal heat of water vapor per 1 ton of styrene.

High-boiling products formed 0.03 g per 1 ton of styrene.

Example 2 (the proposed method).

Dehydrogenation of ethylbenzene is carried out according to the scheme and process conditions specified in example 1.

Evaporation and overheating of etilbenzene fraction occurs under vacuum to 0.8-0.9 ATA in a mixture with steam condensate in the ratio of 1:0.3 to - ethylbenzophenone fraction of 1.76 tons, steam condensate 0,58 t 1 t styrene.

Heating of the mixture is carried out first by the heat of the steam condensate from the circulating line foam device, then evaporation and initial overheating is due to the indirect contact with a mixture of water vapor coming from the waste heat boilers and interstage superheater gas contact, the final overheating due to the heat contact of the gas after the last stage of dehydrogenation.

The cost of heat for evaporation and overheating of etilbenzene fraction accounted for 0.74 Gcal 1 per formed of 0.15 tons per 1 ton of styrene.

Example 3 (the proposed method).

Dehydrogenation of ethylbenzene is carried out according to the scheme and process conditions specified in example 1.

Evaporation and overheating of etilbenzene fraction occurs under vacuum to 0.8-0.9 ATA mixed with water condensate and steam in a ratio of 1: 0,2: 0,1 - ethylbenzene faction in the number of 1.76 tons, steam condensate 0,35 t 1 t styrene, 0,17 t of water vapor per 1 ton of styrene.

Evaporation and overheating of the mixture but the diagram and operating conditions specified in example 2.

The cost of heat for evaporation and overheating of etilbenzene faction by this method is 0,84 Gcal per 1 ton of styrene.

Saving water vapor is 0.15 Gcal/t of styrene, high-boiling products formed of 0.015 t/t styrene.

Thus, the introduction of schemes vacuum evaporation and overheating etilbenzene fraction together with the steam condensate will reduce the specific consumption of water vapor 0.15-0.22-calories per 1 ton of styrene, high-boiling products of 0.015 t/t styrene.

It would ensure efficient use of steam condensate produced by condensation of the contact strip, and reduced formation of high-boiling product is of Anzola in-methylsterol is conducted according to the technological scheme and modes, mentioned in example 1.

The dehydrogenation is served isopropylbenzene fraction of the following composition: isopropylbenzene 98,0 wt. % benzene 0.2 wt. % toluene, and 0.28 wt.%, -methylsterol of 1.52 wt.%. Isopropylbenzene fraction is mixed with steam in a ratio of 1:0.3 weight and is supplied to the evaporation pressure of 1.5 ATA.

The evaporation and overheating 1,76 t isopropylbenzene fraction spent 1,0 Gcal of heat, forming a high-boiling product in 28 kg/t-methylstyrene.

Example 5 (the proposed method).

The dehydrogenation of cumene is but technological scheme and the modes described in example 1.

Evaporation and overheating isopropylbenzene fraction is carried out under vacuum to 0.8-0.9 ATA in the diagram in example 2. On evaporation from isopropylbenzene fraction is fed steam condensate in the ratio of 1:0,3, i.e. 1.76 t isopropylbenzene faction is served 0,58 t steam condensate. This uses excess steam condensate taken from the foam device, after the partial condensation of the contact strip.

For evaporation and overheating isopropylbenzene faction in the number of 1.76 tons of spent 0,78 Gcal of heat, about the="ptx2">

Heat saving water vapor are 0.22 Gcal/t-methylstyrene.

Example 6 (the proposed method).

The dehydrogenation isopropylbenzene faction in-methylsterol administered according to the technological scheme and the modes described in example 1.

Evaporation and overheating isopropylbenzene fraction is carried out under vacuum to 0.8-0.9 ATA according to the scheme shown in example 2.

For evaporation and overheating served isopropylbenzene fraction in the mixture with steam condensate and steam in a weight ratio of 1:0,2:0,1 according to the scheme given in example 3. While 1.76 t isopropylbenzene faction is served 0,35 t steam condensate and 0.17 t water vapor.

The cost of heat for evaporation and overheating of 0.85 Gcal/t-methylstyrene. Saving water vapor will be 0.15 Gcal/t of styrene, education unsocketed - 15 kg/t-methylstyrene.

Thus, implementation of the proposed schemes vacuum evaporation and overheating of alkylaromatic hydrocarbons will reduce the specific consumption of water vapor 0.15-0.22 Gcal target product.

It would ensure efficient use of the excess steam condensate obtained at the node of cooling the account "soft" mode vacuum evaporation.

1. The method of obtaining vinylaromatic hydrocarbons by catalytic dehydrogenation of alkylaromatic hydrocarbons in a multistage reactor at an elevated temperature in the presence of water vapor under vacuum, including evaporation, overheating alkylaromatic hydrocarbon, characterized in that the evaporation and overheating alkylaromatic hydrocarbon is carried out under vacuum to 0.8-0.9 ATA mixed with purified steam condensate produced by the partial condensation of the contact gas, in a ratio of 1:0.3 weight at first due to the heat of the steam condensate, circulating in the foam apparatus, then through indirect contact with a mixture of water vapor coming from the waste heat boilers and interstage superheater gas contact and finally, due to the heat contact of the gas after the last stage of dehydrogenation.

2. The method according to p. 1, characterized in that the evaporation and overheating alkylaromatic hydrocarbon is carried out in a mixture with purified steam condensate and steam in a ratio of 1:0,2:0,1 by weight, respectively.

 

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FIELD: petrochemical processes.

SUBSTANCE: method provides for three-stage isolation of aromatic hydrocarbons in the separation, absorption, and separation stages using, as absorbent, ethylbenzene rectification bottom residue. Loaded absorbent containing diethylbenzene isomer mixture serves as starting material for production of alkylaromatic hydrocarbons including divinylbenzene.

EFFECT: reduced loss of aromatic hydrocarbons and improved economical efficiency of styrene production process.

2 dwg, 1 tbl, 5 ex

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