CN114456037A - Raw material gasification method for preparing styrene by ethylbenzene dehydrogenation - Google Patents
Raw material gasification method for preparing styrene by ethylbenzene dehydrogenation Download PDFInfo
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- CN114456037A CN114456037A CN202011134032.2A CN202011134032A CN114456037A CN 114456037 A CN114456037 A CN 114456037A CN 202011134032 A CN202011134032 A CN 202011134032A CN 114456037 A CN114456037 A CN 114456037A
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- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 title claims abstract description 672
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 title claims abstract description 125
- 238000006356 dehydrogenation reaction Methods 0.000 title claims abstract description 80
- 239000002994 raw material Substances 0.000 title claims abstract description 49
- 238000000034 method Methods 0.000 title claims abstract description 42
- 238000002309 gasification Methods 0.000 title claims abstract description 30
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 239
- 238000000926 separation method Methods 0.000 claims abstract description 83
- 239000000463 material Substances 0.000 claims abstract description 68
- 239000007791 liquid phase Substances 0.000 claims abstract description 40
- 239000000203 mixture Substances 0.000 claims abstract description 39
- 239000012071 phase Substances 0.000 claims abstract description 38
- 238000001704 evaporation Methods 0.000 claims abstract description 32
- 238000006243 chemical reaction Methods 0.000 claims abstract description 31
- 230000008020 evaporation Effects 0.000 claims abstract description 28
- 239000007788 liquid Substances 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims description 54
- 230000000295 complement effect Effects 0.000 claims description 6
- 239000006200 vaporizer Substances 0.000 claims description 6
- 230000000153 supplemental effect Effects 0.000 claims description 4
- 239000012808 vapor phase Substances 0.000 claims description 3
- 238000005265 energy consumption Methods 0.000 abstract description 23
- 239000003054 catalyst Substances 0.000 abstract description 15
- 238000011084 recovery Methods 0.000 abstract description 4
- 239000007858 starting material Substances 0.000 description 14
- YFPBWJDUUHCRBT-UHFFFAOYSA-N ethylbenzene;hydrate Chemical compound O.CCC1=CC=CC=C1 YFPBWJDUUHCRBT-UHFFFAOYSA-N 0.000 description 13
- 238000005516 engineering process Methods 0.000 description 6
- 230000008016 vaporization Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000013589 supplement Substances 0.000 description 4
- 230000009469 supplementation Effects 0.000 description 4
- 238000009834 vaporization Methods 0.000 description 4
- 239000004816 latex Substances 0.000 description 3
- 229920000126 latex Polymers 0.000 description 3
- 229920003048 styrene butadiene rubber Polymers 0.000 description 3
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 2
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 2
- 239000004793 Polystyrene Substances 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- VEFXTGTZJOWDOF-UHFFFAOYSA-N benzene;hydrate Chemical compound O.C1=CC=CC=C1 VEFXTGTZJOWDOF-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 description 1
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- 239000004480 active ingredient Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229920006026 co-polymeric resin Polymers 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 239000010779 crude oil Substances 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000008236 heating water Substances 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000005839 oxidative dehydrogenation reaction Methods 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229920006305 unsaturated polyester Polymers 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
- C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
- C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
- C07C5/333—Catalytic processes
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Abstract
The invention provides a raw material gasification method for preparing styrene by ethylbenzene dehydrogenation, which comprises the steps of enabling a material flow VI comprising raw material ethylbenzene and raw material water to enter an ethylbenzene/water separation tank to obtain a liquid-phase ethylbenzene/water mixture; partially gasifying the liquid-phase ethylbenzene/water mixture through an azeotropic heat exchanger to obtain a material flow I, wherein the material flow I comprises a gas-phase ethylbenzene/water azeotropic material flow II and a gas-liquid mixture III; and feeding the raw material ethylbenzene IV and the gas-phase ethylbenzene/water azeotropic material flow II into an ethylbenzene supplementary evaporator, completely gasifying to obtain a material flow V, and feeding the material flow V into a subsequent reaction system. The method reduces the water distribution amount of the ethylbenzene evaporation system by 25-35%, increases the main steam amount, ensures the use of the low-water-ratio dehydrogenation catalyst, further reduces the consumption of steam and circulating water, improves the low-temperature heat recovery rate of the top of the ethylbenzene/styrene tower, and reduces the energy consumption of the device.
Description
Technical Field
The invention relates to a raw material gasification method for preparing styrene by ethylbenzene dehydrogenation.
Background
Styrene is one of the most important basic organic chemical raw materials, and is mainly used for manufacturing polystyrene PS and EPS, ABS, SAN and other copolymer resins, styrene/butadiene copolymer latex SB, styrene-butadiene rubber and latex SBR, unsaturated polyester, and other materials such as styrene/methyl methacrylate latex, methyl methacrylate/butadiene/styrene copolymer MBS, ion exchange resin, medicines and the like.
The production technology for preparing styrene by ethylbenzene dehydrogenation mainly comprises an adiabatic dehydrogenation process, an isothermal dehydrogenation process, a selective oxidative dehydrogenation process and a propylene oxide co-oxidation process. The most widely used and technically mature process is the ethylbenzene negative pressure adiabatic dehydrogenation process, which accounts for about 85% of the worldwide styrene yield.
In the presence of catalyst and steam, ethylbenzene is subjected to selective dehydrogenation reaction at 550-650 ℃ to generate styrene. The reaction is a strong endothermic reaction, a large amount of superheated steam is added, on one hand, the superheated steam is a heat carrier for ethylbenzene dehydrogenation reaction and provides heat required by the reaction, on the other hand, the existence of the steam reduces reaction partial pressure and is beneficial to the generation of styrene, the steam can also generate water gas reaction with carbon deposition shown by a catalyst, active ingredients of the catalyst can be prevented from being reduced into metal, the service life of the catalyst is prolonged, and the water ratio (the weight ratio of the steam to the ethylbenzene) adopted in industry is 1-1.6.
The production process of the styrene needs a large amount of fuel and water vapor, and the process energy consumption is large. With the continuous increase of the prices of crude oil and raw materials, the adoption of an energy-saving technology becomes a key measure for reducing the cost of a styrene device. The energy-saving problem of styrene devices at home and abroad is widely researched, and patent CN1007973B provides an improved dehydrogenation process for producing styrene from styrene, which comprises low-temperature heat recovery and an improved method of styrene-steam feeding, wherein the heat at the top of an ethylbenzene/styrene separation tower is used for heating ethylbenzene and water, part of ethylbenzene raw material and water enter a reactor in an azeotropic manner, so that the energy consumption is saved by 10-20%, and the method is already applied to industrial devices.
The energy consumption of the device can be effectively reduced by reducing the water ratio, the research of the dehydrogenation catalyst with the low water ratio is greatly improved in recent years, the water ratio is reduced from 1.4-1.6 to 1-1.25, the water ratio is reduced from 1.4 to 1.1, the comprehensive energy consumption of the device is reduced by about 10 percent, and the economic benefit is considerable. If the low water ratio catalyst is used in the device built by the original azeotropic energy-saving styrene technology, the water amount supplied to the ethylbenzene evaporation system cannot be reduced, the heat of water vapor entering a heating furnace must be reduced by applying the low water ratio dehydrogenation catalyst, the heat required by the ethylbenzene dehydrogenation reaction is basically unchanged, the steam flow entering the heating furnace is reduced, and the outlet temperature of the corresponding heating furnace must be increased. When the water ratio is 1.4, the outlet temperatures of the steam heating furnace A and the steam heating furnace B are respectively 850 ℃ and 830 ℃. When the water ratio is reduced to 1.25, the outlet temperatures of the steam heating furnaces A and B are 890 ℃ and 870 ℃ respectively. When the water ratio is reduced to 1.0, the outlet temperatures of the steam heating furnaces A and B are 940 ℃ and 930 ℃ respectively. The catalyst is limited by the upper limit of the use temperature of the heating furnace pipeline material, and the catalyst cannot be directly used on the device built by the originally adopted azeotropic energy-saving styrene technology when the water ratio is less than or equal to 1.2. In order to solve the problem, CN103030522B proposes that an integrated system of ethylbenzene/water azeotropic evaporation and ethylbenzene complementary evaporation is adopted for separation, and an independent ethylbenzene complementary evaporation system is arranged, so that the problem of common use of catalysts with constant boiling and low water ratio in sequential separation is solved. The low-temperature heat at the top of the ethylbenzene/styrene tower is utilized by about 92% by adopting the original sequential azeotropic energy-saving process, an independent ethylbenzene supplementary evaporator is arranged, part of the raw material ethylbenzene is directly evaporated by adopting steam as a heat source, the low-temperature heat utilization rate of the top of the ethylbenzene/styrene tower is reduced by about 75%, the consumption of cooling water and chilled water at the top of the tower is increased, and the consumption of steam is increased by evaporating part of the ethylbenzene. In order to avoid the accumulation of components such as styrene in the ethylbenzene feeding, the operation temperature of the ethylbenzene supplementary evaporator is controlled, a small amount of water vapor needs to be added into the ethylbenzene evaporator, and the water vapor consumption is further increased. The increase of the consumption of cooling water, chilled water, steam and other public works partially offsets the reduction of energy consumption caused by the adoption of the low-water-ratio catalyst.
Disclosure of Invention
The invention aims to solve the technical problems that an independent ethylbenzene evaporation system is arranged by adopting a low-water-ratio sequential azeotropic energy-saving process in the prior art, and in order to avoid the accumulation of components such as styrene in ethylbenzene, the independent ethylbenzene evaporation system needs to be added with water vapor, so that the problems of insufficient low-temperature heat utilization of a rectification system, high water vapor and circulating water consumption and high device energy consumption exist. Therefore, the invention provides a novel raw material gasification method for preparing styrene by ethylbenzene dehydrogenation with low water ratio, which has the characteristics of further reducing the consumption of water vapor and circulating water and reducing the energy consumption of a device when the styrene device simultaneously applies an azeotropic energy-saving process and a low water ratio catalyst.
The first aspect of the invention provides a raw material gasification method for preparing styrene by ethylbenzene dehydrogenation, which comprises the following steps:
s1: feeding a material flow VI comprising raw material ethylbenzene and raw material water into an ethylbenzene/water separation tank to obtain a liquid-phase ethylbenzene/water mixture;
s2: partially gasifying the liquid-phase ethylbenzene/water mixture through an azeotropic heat exchanger to obtain a material flow I, wherein the material flow I comprises a gas-phase ethylbenzene/water azeotropic material flow II and a gas-liquid mixture III;
s3: and feeding the raw material ethylbenzene IV and the gas-phase ethylbenzene/water azeotropic material flow II into an ethylbenzene supplementary evaporator, completely gasifying to obtain a material flow V, and feeding the material flow V into a subsequent reaction system.
According to some embodiments of the invention, the method further comprises S4: and returning the gas-liquid mixture III to the ethylbenzene/water separation tank to obtain a gas-phase outlet material flow VII, and feeding the material flow VII into a subsequent reaction system.
According to a preferred embodiment of the present invention, the stream V and the stream VII are mixed to obtain a stream VIII, and the stream VIII enters a subsequent reaction system.
According to some embodiments of the present invention, the weight percentage of feed water in stream VI is 30-40%, and may be, for example, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, and any value therebetween.
According to some embodiments of the invention, the rate of gasification of the stream I is between 4% and 20%, and may be, for example, 6%, 8%, 10%, 12%, 14%, 16%, 18%, and any value in between.
According to some embodiments of the invention, the stream II comprises 5-15% by mass of the feed ethylbenzene IV, for example 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% and any value in between.
According to some embodiments of the invention, the mass fraction of water in the stream V is between 5 and 10%, and may be, for example, 6%, 7%, 8%, 9% and any value in between.
According to some embodiments of the present invention, the vapor phase ethylbenzene/water azeotrope stream II is fed to the ethylbenzene supplemental evaporator in a plurality of times, preferably 1-3 times, in S3.
According to some embodiments of the invention, the feed ethylbenzene IV comprises 10-35% by mass of the total feed ethylbenzene and the ethylbenzene in stream VI comprises 65-90% by mass of the total feed ethylbenzene.
According to some embodiments of the invention, the feed ethylbenzene IV comprises 15%, 20%, 25%, 30% and any value therebetween of the total feed ethylbenzene mass.
According to some embodiments of the invention, the ethylbenzene in stream VI comprises 70%, 75%, 80%, 85% and any value in between of the total feed ethylbenzene mass.
According to a preferred embodiment of the present invention, the raw ethylbenzene IV is comprised between 12 and 30% of the total raw ethylbenzene mass; the ethylbenzene in the stream VI accounts for 70-88% of the mass of the total raw material ethylbenzene.
According to some embodiments of the invention, the ethylbenzene/water separation tank is operated at a pressure of 70-120kPaA and a temperature of 85-97 deg.C.
According to some embodiments of the invention, the operating pressure of the azeotropic heat exchanger is in the range of from 70 to 120kPaA and the temperature is in the range of from 85 to 97 ℃.
According to some embodiments of the present invention, the ethylbenzene make-up vaporizer is operated at a pressure of 80-120KPaA and at a temperature of 100-.
According to some embodiments of the invention, the stream VIII has a pressure of from 80 to 120kPaA and a temperature of from 85 to 130 ℃.
According to some embodiments of the invention, the azeotropic vaporizer uses ethylbenzene/styrene splitter overhead gas as a heat source.
According to some embodiments of the invention, the ethylbenzene make-up vaporizer is heated with steam.
According to some embodiments of the invention, the subsequent reaction system comprises a dehydrogenation reaction system, a steam heating system, or the like.
According to some embodiments of the invention, the dehydrogenation reaction system comprises a dehydrogenation reactor, preferably the dehydrogenation reactor comprises a first dehydrogenation reactor and a second dehydrogenation reactor.
According to some embodiments of the invention, the weight ratio of water and ethylbenzene in the dehydrogenation reactor is between 0.9 and 1.3: 1.
according to some embodiments of the invention, the dehydrogenation reaction is operated at a pressure of 50-75kPaA and at a temperature of 580-650 ℃.
According to some embodiments of the invention, the steam heating system comprises a steam heating furnace.
According to some embodiments of the present invention, the outlet temperature of the chamber A of the steam heating furnace is 800-.
According to some specific embodiments of the invention, the method comprises the steps of: a) feeding a material flow VI containing raw material ethylbenzene and water into an ethylbenzene/water separation tank, partially vaporizing a separated liquid-phase ethylbenzene/water mixture by an ethylbenzene/styrene tower top azeotropic heat exchanger to obtain a material flow I, and subjecting the material flow I to vapor-liquid separation to obtain a gas-phase material flow II and a vapor-liquid mixture III, wherein the vaporization rate of the material flow I is 4-20%, and the gas-phase material flow II is an ethylbenzene/water azeotrope under the shell side operating pressure of the azeotropic heat exchanger; b) feeding ethylbenzene IV as a raw material into an ethylbenzene supplementary evaporator, and feeding a gas-phase ethylbenzene/water azeotropic material flow II into the ethylbenzene supplementary evaporator in 1-3 strands, and completely vaporizing to obtain a material flow V; c) separating after partial vaporization obtained in the step a) to obtain a vapor-liquid mixture III, returning the vapor-liquid mixture III to an ethylbenzene/water separation tank to obtain a vapor phase outlet material flow VII, wherein the weight percentage of water in the material flow VI is 30-40%; d) and mixing the material flow V and the material flow VII to obtain a material flow VIII, and feeding the material flow VIII into a subsequent reaction system.
The second aspect of the invention provides a system for implementing the method according to the first aspect, which comprises an azeotropic evaporation system, an ethylbenzene supplementary evaporation system, an ethylbenzene/water separation system, a steam heating system and a dehydrogenation reaction system, wherein an ethylbenzene/water mixture partially gasified by the azeotropic evaporation system is separated into a gas-phase ethylbenzene/water azeotrope material flow II, the gas-phase ethylbenzene/water azeotrope material flow II and a raw material ethylbenzene IV enter the ethylbenzene supplementary evaporation system, and a material flow V obtained after gasification enters the dehydrogenation reaction system for reaction.
According to some embodiments of the present invention, the gas-liquid mixture III is separated from the ethylbenzene/water mixture after being partially gasified by the azeotropic evaporation system, and the gas-liquid mixture III is gasified in the ethylbenzene/water separation system to obtain a gas phase outlet stream VII, which is sent to the dehydrogenation reaction system for reaction.
According to some embodiments of the present invention, the stream V and the stream VII are mixed and then enter a dehydrogenation reaction system for reaction.
According to some embodiments of the invention, the azeotropic vaporization system comprises an azeotropic heat exchanger.
According to some embodiments of the invention, the ethylbenzene supplemental vaporization system comprises an ethylbenzene supplemental vaporizer.
According to some embodiments of the invention, the ethylbenzene/water separation system comprises an ethylbenzene/water separation tank.
According to some embodiments of the invention, the dehydrogenation reaction system comprises a dehydrogenation reactor, preferably the dehydrogenation reactor comprises a first dehydrogenation reactor and a second dehydrogenation reactor.
According to some embodiments of the invention, the weight ratio of water and ethylbenzene in the dehydrogenation reactor is between 0.9 and 1.3: 1.
according to some embodiments of the present invention, the dehydrogenation reactor is operated at a pressure of 50-75kPaA and a temperature of 580-650 ℃.
According to some embodiments of the invention, the dehydrogenation reaction system further comprises an intermediate heat exchanger and/or a superheater.
According to some embodiments of the invention, the steam heating system comprises a steam heating furnace.
According to some embodiments of the present invention, the outlet temperature of the chamber A of the steam heating furnace is 800-.
According to some embodiments of the invention, the system further comprises a tail gas cooler, a tail gas subcooler, and an ethylbenzene/styrene splitter.
A third aspect of the invention provides a use of the method according to the first aspect or the system according to the second aspect for the dehydrogenation of ethylbenzene to styrene.
In the invention, an independent ethylbenzene complementary evaporation system is arranged, a part of gas-phase ethylbenzene/water azeotrope separated from the ethylbenzene/water mixture after partial gasification by the azeotropic heat exchanger enters the ethylbenzene complementary evaporation system together with ethylbenzene according to a certain proportion, and enters the dehydrogenation reaction system after evaporation is finished. The ethylbenzene supplementary evaporating system takes steam as a heat source, and completely gasifies and evaporates ethylbenzene and water by reducing the water distribution ratio, the weight content of ethylbenzene/water feeding water in a dehydrogenation reactor is reduced to 0-20% from the original azeotropic composition, the ethylbenzene/water azeotropic evaporating system maintains the original process conditions, part of raw material ethylbenzene and water are gasified, the weight content of water is about 33%, the water distribution amount of the raw material ethylbenzene evaporating system is reduced by 25-35%, the main steam amount is increased, the use of a low-water-ratio dehydrogenation catalyst is ensured, the consumption of steam and circulating water is further reduced, the low recovery rate of the top of an ethylbenzene/styrene tower is improved, and the energy consumption of a device is reduced.
By adopting the technical scheme of the invention, when the azeotropic energy-saving process is applied, the water distribution can be reduced by 25-35%, the low-water-ratio dehydrogenation catalyst and the azeotropic energy-saving process can be ensured to be used simultaneously, and the ethylbenzene/water azeotrope and the ethylbenzene enter an ethylbenzene supplementary evaporation system together, so that the water vapor and circulating water consumption is further reduced, the low-temperature heat recovery rate of the top of the ethylbenzene/styrene tower is improved, and the energy consumption of a device is reduced. When the water ratio is 1.0, the liquefaction rate of the ethylbenzene/styrene overhead gas through the azeotropic heat exchanger is improved to 0.82 from 0.75 of the prior independent ethylbenzene supplementary evaporation scheme, the water vapor is not required to be added into an ethylbenzene supplementary evaporator, the heating water vapor of the ethylbenzene supplementary evaporator is reduced by 15%, the circulating water consumption at the top of the ethylbenzene/styrene separation tower is reduced by 27%, the energy consumption of a device is reduced by 4.5kgoe/t.SM, the effect of the sequential separation energy-saving process is more prominent, and a better technical effect is obtained.
Drawings
FIG. 1 is a flow diagram of a process for the dehydrogenation of ethylbenzene to styrene in the prior art.
FIG. 2 is a flow diagram of a process for the dehydrogenation of ethylbenzene to styrene in accordance with the present invention.
In fig. 1 and 2, 1 is a steam heating furnace, 2 is a first dehydrogenation reactor, 3 is a second dehydrogenation reactor, 4 is an intermediate heat exchanger, 5 is an ethylbenzene supplementary evaporator, 6 is an ethylbenzene/water separation tank, 7 is a superheater, 8 is an azeotropic heat exchanger, 9 is a tail gas cooler, 10 is a tail gas subcooler, and 11 is an ethylbenzene/styrene separation tower. 101 is steam entering a chamber A of a steam heating furnace, 102 is steam exiting the chamber A of the steam heating furnace, 103 is steam entering the chamber B of the steam heating furnace, 104 is steam exiting the chamber B of the steam heating furnace, 105 is water distribution, 106 is raw material ethylbenzene, 107 is an ethylbenzene-water mixture, 108 is an ethylbenzene evaporator to supplement ethylbenzene, 109 is discharged from the ethylbenzene evaporator, 110 is discharged from a first dehydrogenation reactor, 111 is discharged from a middle heat exchanger tube layer, 112 is discharged from a second dehydrogenation reactor, 113 is an ethylbenzene-water mixture, 114 is a superheater tube pass outlet, 115 is fed from a shell side of the ethylbenzene evaporator, 116 is discharged from an ethylbenzene/water separation tank, 118 is discharged from the ethylbenzene/water separation tank, 122 is discharged from a tube pass of an azeotropic heat exchanger, 123 is fed from a tube pass of the azeotropic heat exchanger, 124 is discharged from a top gas phase of an ethylbenzene/styrene tower, 125 is fed from an ethylbenzene evaporator and 126 is discharged from a shell side of a tail gas cooler, discharging from the shell side of a 127 tail gas subcooler, separating part of gas-phase ethylbenzene/water azeotrope from a 128 return product of an ethylbenzene/water separation tank, sending 129 ethylbenzene to the ethylbenzene/water separation tank, distributing 130 water to the ethylbenzene/styrene separation tank, and distributing 131 water to an ethylbenzene evaporator.
In fig. 1, the raw material ethylbenzene 106 is divided into two streams 129 and 108, the water distribution 105 is also divided into 2 streams 130 and 131, a part of the ethylbenzene 129 and the water distribution 130 jointly enter the ethylbenzene/water separation tank 6, the other part of the ethylbenzene 108 and the water distribution 131 jointly enter the ethylbenzene evaporator 5, the ethylbenzene/water separation tank separates liquid-phase ethylbenzene and liquid-phase water, the liquid-phase ethylbenzene 118 and the liquid-phase water 116 enter the azeotropic heat exchanger 8 for partial gasification, the heat source is overhead gas of the ethylbenzene/styrene tower 11, a gas-liquid mixture 122 after partial gasification returns to the ethylbenzene/water separation tank 6, the water distribution 131 and the liquid-phase ethylbenzene 108 are mixed and then enter the ethylbenzene evaporator 5, the liquid-phase ethylbenzene 118 and the liquid-phase water 116 are completely gasified in the ethylbenzene supplementary evaporator 5, and the gasified material stream 109 and the gas-phase outlet material of the ethylbenzene/water separation tank 6 are mixed and enter the superheater 7 for heating, and then the material 113 enters the first dehydrogenation reactor 2 for reaction.
In fig. 2, a raw material ethylbenzene 106 is divided into two streams, a part of ethylbenzene 129 and a steam distribution 105 enter an ethylbenzene/water separation tank 6 together, the other part of ethylbenzene 108 enters an ethylbenzene evaporator 5, the ethylbenzene/water separation tank separates liquid-phase ethylbenzene and liquid-phase water, the liquid-phase ethylbenzene 118 and the liquid-phase water 116 enter an azeotropic heat exchanger 8 for partial gasification, a heat source is overhead gas of an ethylbenzene/styrene tower 11, a gas-liquid mixture after partial gasification is divided into two streams, one stream is a gas-phase ethylbenzene/water azeotrope 125 and is mixed with the liquid-phase ethylbenzene 108 and then enters the ethylbenzene evaporator 5, the other stream of ethylbenzene/water mixture returns to the ethylbenzene/water separation tank 6, a gas phase at the top of the ethylbenzene/styrene tower 11 passes through the azeotropic heat exchanger 8 and a tail gas cooler 9, the tail gas subcooler 10 enters a tower top vacuum system, and the material 113 obtained by heating the gas phase discharged material of the ethylbenzene/water separation tank 6 by the heater 7 enters the first dehydrogenation reactor 2 for reaction.
Detailed Description
The invention provides a method for gasifying a raw material for preparing styrene by ethylbenzene dehydrogenation with a low water ratio, and the process flow is shown in figure 1.
In fig. 1, 1 is a steam heating furnace, 2 is a first dehydrogenation reactor, 3 is a second dehydrogenation reactor, 4 is an intermediate heat exchanger, 5 is an ethylbenzene evaporator, 6 is an ethylbenzene/water separation tank, 7 is a superheater, 8 is an azeotropic heat exchanger, 9 is a tail gas cooler, 10 is a tail gas subcooler, and 11 is an ethylbenzene/styrene separation tower. 101 is steam entering a chamber A of a steam heating furnace, 102 is steam exiting the chamber A of the steam heating furnace, 103 is steam entering the chamber B of the steam heating furnace, 104 is steam exiting the chamber B of the steam heating furnace, 105 is water distribution, 106 is raw material ethylbenzene, 107 is an ethylbenzene-water mixture, 108 is an ethylbenzene evaporator to supplement ethylbenzene, 109 is discharged from the ethylbenzene evaporator, 110 is discharged from a first dehydrogenation reactor, 111 is discharged from a middle heat exchanger tube layer, 112 is discharged from a second dehydrogenation reactor, 113 is an ethylbenzene-water mixture, 114 is a superheater tube pass outlet, 115 is fed from a shell side of the ethylbenzene evaporator, 116 is discharged from an ethylbenzene/water separation tank, 118 is discharged from the ethylbenzene/water separation tank, 122 is discharged from a tube pass of an azeotropic heat exchanger, 123 is fed from a tube pass of the azeotropic heat exchanger, 124 is discharged from a top gas phase of an ethylbenzene/styrene tower, 125 is fed from an ethylbenzene evaporator and 126 is discharged from a shell side of a tail gas cooler, discharging 127 tail gas from the shell side of the subcooler, separating 128 part of gas phase ethylbenzene/water azeotrope, returning from the ethylbenzene/water separation tank, sending 129 ethylbenzene to the ethylbenzene/water separation tank, distributing 130 water to the ethylbenzene/styrene separation tank, and distributing 131 water to the ethylbenzene evaporator.
In fig. 1, the raw material ethylbenzene 106 is divided into two streams 129 and 108, the water distribution 105 is also divided into 2 streams 130 and 131, a part of the ethylbenzene 129 and the water distribution 130 jointly enter the ethylbenzene/water separation tank 6, the other part of the ethylbenzene 108 and the water distribution 131 jointly enter the ethylbenzene evaporator 5, the ethylbenzene/water separation tank separates liquid-phase ethylbenzene and liquid-phase water, the liquid-phase ethylbenzene 118 and the liquid-phase water 116 enter the azeotropic heat exchanger 8 for partial gasification, the heat source is overhead gas of the ethylbenzene/styrene tower 11, a gas-liquid mixture 122 after partial gasification returns to the ethylbenzene/water separation tank 6, the water distribution 131 and the liquid-phase ethylbenzene 108 are mixed and then enter the ethylbenzene evaporator 5, the liquid-phase ethylbenzene 118 and the liquid-phase water 116 are completely gasified in the ethylbenzene supplementary evaporator 5, and the gasified material stream 109 and the gas-phase outlet material of the ethylbenzene/water separation tank 6 are mixed and enter the superheater 7 for heating, and then the material 113 enters the first dehydrogenation reactor 2 for reaction.
For easy understanding of the present invention, the present invention will be described in detail with reference to examples, which are provided for illustrative purposes only and are not intended to limit the scope of the present invention.
The starting materials or components used in the present invention may be commercially or conventionally prepared unless otherwise specified.
[ example 1 ]
In a 12-ten-thousand-ton/year styrene device (8000 hours of annual operation), the technology for preparing styrene by ethylbenzene dehydrogenation shown in figure 2 is adopted, the flow of raw material ethylbenzene is 24 tons/hour and is divided into two paths, the two paths enter an ethylbenzene/water separation tank for 17.8 tons/hour, the flow of the raw material ethylbenzene enters an ethylbenzene supplementary evaporator for 6.2 tons/hour, the total water distribution flow is 8.8 tons/hour, and the whole path enters the ethylbenzene/water separation tank. The ethylbenzene/water separation tank separates liquid phase ethylbenzene and water, the liquid phase ethylbenzene and water enter the azeotropic heat exchanger under the control of a circulating pump, the gasification rate is 4.7%, the separated gas phase ethylbenzene/water azeotrope enters the ethylbenzene supplementary evaporator in 3 strands at 2 tons/hour, the liquefaction rate of the overhead gas of the ethylbenzene/styrene separation tower after passing through the azeotropic heat exchanger is 0.82, the circulating water consumption of the tail gas cooler is 176 tons/hour, the ethylbenzene supplementary evaporator heats 1.2 tons/hour of steam, and the mass content of outlet water of the ethylbenzene supplementary evaporator is 8%. The operating pressure of the azeotropic evaporator is 100kPaA, the evaporation temperature is 91 ℃, the overhead gas of the ethylbenzene/styrene separation tower is used as a heat source, the overhead pressure is 36kPaA, and the temperature is 101 ℃. The ethylbenzene supplementary evaporator adopts a kettle type heat exchanger structure, raw material ethylbenzene and gas-phase ethylbenzene water azeotrope are completely gasified in a shell pass, a tube pass is heated by 0.35MPa of steam, the operating pressure is 98kPaA and the temperature is 120 ℃, the gasified material is mixed with a gas-phase outlet material of an ethylbenzene/water separation tank, the temperature after mixing is 98 ℃, the operating pressure is 98kPaA, the mixture is heated to 520 ℃ by a heater, the steam from a steam heating furnace sequentially enters a first dehydrogenation reactor, an intermediate heat exchanger and a second dehydrogenation reactor, the steam mass flow rate of the steam enters a steam heating furnace is 15.3 tons/hour, the outlet temperature of a chamber A of the steam heating furnace is 878 ℃, and the outlet temperature of a chamber B of the steam heating furnace is 872 ℃; the operating pressure of the first dehydrogenation reactor was 54 kPaA; the reaction temperature is 623 ℃, the operating pressure of the second dehydrogenation reactor is 44kPaA, and the reaction temperature is 623 DEG C
The water ratio of the device is 1.0, the ethylbenzene supplementary evaporator heats steam by 1.2 tons/hour, the tail gas cooler circulating water consumption is 176 tons/hour, and the device energy consumption is 253 kgoe/t.SM.
[ example 2 ]
In a 12-ten-thousand-ton/year styrene device (8000 hours of annual operation), the technology for preparing styrene by ethylbenzene dehydrogenation shown in figure 2 is adopted, the flow of raw material ethylbenzene is 24 tons/hour and is divided into two paths, the two paths enter an ethylbenzene/water separation tank for 21.1 tons/hour, enter an ethylbenzene supplementary evaporator for 2.9 tons/hour, the total water distribution flow is 10.6 tons/hour, and all the paths enter the ethylbenzene water separation tank. The ethylbenzene/water separation tank separates liquid-phase ethylbenzene and water, the liquid-phase ethylbenzene and water enter the azeotropic heat exchanger under the control of a circulating pump, the gasification rate is 5%, the separated gas-phase ethylbenzene/water azeotrope enters the ethylbenzene supplementary evaporator in 2 strands at 0.9 ton/hour, the overhead gas of the ethylbenzene/styrene separation tower passes through the azeotropic heat exchanger, the liquefaction rate is 0.97, the circulating water consumption of the tail gas cooler is 30 ton/hour, the ethylbenzene supplementary evaporator heats 0.6 ton/hour of steam, and the mass content of outlet water of the ethylbenzene supplementary evaporator is 8%. The operating pressure of the azeotropic evaporator is 100kPaA, the evaporation temperature is 91 ℃, the overhead gas of the ethylbenzene/styrene separation tower is used as a heat source, the overhead pressure is 36kPaA, and the temperature is 101 ℃. The ethylbenzene supplementary evaporator adopts a kettle type heat exchanger structure, raw material ethylbenzene and gas-phase ethylbenzene water azeotrope are completely gasified in a shell pass, a tube pass is heated by 0.35MPa of water vapor, the pressure after gasification is 98kPaA, the temperature is 120 ℃, the gasified material is mixed with the gas-phase outlet material of an ethylbenzene/water separation tank, the temperature after mixing is 98 ℃, the pressure is 98kPaA, the mixture is heated to 520 ℃ by a heater, the water vapor from a steam heating furnace sequentially enters a first dehydrogenation reactor, an intermediate heat exchanger and a second dehydrogenation reactor, the mass flow of the water vapor enters a steam heating furnace for 16.1 tons/hour, the outlet temperature of a chamber A of the steam heating furnace is 878 ℃, the outlet temperature of a chamber B of the steam heating furnace is 866 ℃, and the operating pressure of the first dehydrogenation reactor is 54 kPaA; the reaction temperature is 623 ℃, the operating pressure of the second dehydrogenation reactor is 44kPaA, and the reaction temperature is 623 ℃.
The water ratio of the device is 1.1, the ethylbenzene supplementary evaporator heats 0.6 ton/h of steam, the tail gas cooler circulating water consumption is 30 ton/h, and the device energy consumption is 259 kgoe/t.SM.
[ example 3 ]
The difference from example 1 is only that the flow rate of ethylbenzene as a raw material is 24 tons/hour, and the raw material is divided into two flows, namely 2.4 tons/hour in the ethylbenzene/water separation tank, 21.6 tons/hour in the ethylbenzene make-up evaporator, and 8.8 tons/hour in the total water distribution flow, and all the flows enter the ethylbenzene water separation tank.
The water ratio of the device is 1.0, the heating steam of the ethylbenzene evaporator is 4.2 tons/hour, the circulating water consumption of the tail gas cooler is 850 tons/hour, and the energy consumption of the device is 300 kgoe/t.SM.
[ example 4 ]
The difference from example 1 is only that the flow rate of ethylbenzene as a raw material is 24 tons/hour, and the raw material is divided into two flows, namely 4.8 tons/hour in the ethylbenzene/water separation tank, 19.2 tons/hour in the ethylbenzene supplementary evaporator, and 8.8 tons/hour in the total water distribution flow rate, and the whole flows are fed into the ethylbenzene water separation tank.
The water ratio of the device is 1.0, the heating steam of the ethylbenzene evaporator is 3.7 tons/hour, the circulating water consumption of the tail gas cooler is 760 tons/hour, and the energy consumption of the device is 285 kgoe/t.SM.
[ example 5 ]
The difference from example 1 is only that the flow rate of ethylbenzene as a raw material is 24 tons/hour, and the raw material is divided into two flows, namely 8 tons/hour in the ethylbenzene/water separation tank, 16 tons/hour in the ethylbenzene make-up evaporator, and 8.8 tons/hour in the total water distribution flow rate, and the whole flows enter the ethylbenzene water separation tank.
The water ratio of the device is 1.0, the heating steam of the ethylbenzene evaporator is 3.1 tons/hour, the circulating water consumption of the tail gas cooler is 450 tons/hour, and the energy consumption of the device is 273 kgoe/t.SM.
[ example 6 ] A method for producing a polycarbonate
The difference from example 1 is only that the flow rate of ethylbenzene as a raw material is 24 tons/hour, and the raw material is divided into two flows, the two flows enter an ethylbenzene/water separation tank for 12 tons/hour, enter an ethylbenzene make-up evaporator for 12 tons/hour, and the total flow rate of water distribution is 8.8 tons/hour, and all the flows enter the ethylbenzene water separation tank.
The water ratio of the device is 1.0, the heating steam of the ethylbenzene evaporator is 2.3 tons/hour, the circulating water consumption of the tail gas cooler is 380 tons/hour, and the energy consumption of the device is 265 kgoe/t.SM.
[ example 7 ]
The difference from the embodiment 1 is that the ethylbenzene/water separation tank separates liquid-phase ethylbenzene and water, the liquid-phase ethylbenzene and water enter the azeotropic heat exchanger under the control of a circulating pump, the gasification rate is 10%, and the liquid-phase ethylbenzene/water azeotrope is separated out, wherein the liquid-phase ethylbenzene/water azeotrope enters the ethylbenzene supplementary evaporator by 3 strands at a rate of 0.4 ton/hour.
The water ratio of the device is 1.0, the heating steam of the ethylbenzene evaporator is 1.5 tons/hour, the circulating water consumption of the tail gas cooler is 200 tons/hour, and the energy consumption of the device is 260 kgoe/t.SM. The ethylbenzene evaporator can generate the phenomenon that the heat exchanger is blocked by the polymer when the device runs for a long time.
[ example 8 ]
The difference from the embodiment 1 is that the ethylbenzene/water separation tank separates liquid phase ethylbenzene and water, the liquid phase ethylbenzene and water enter the azeotropic heat exchanger under the control of a circulating pump, the gasification rate is 12%, and the separated gas phase ethylbenzene/water azeotrope enters the ethylbenzene supplementary evaporator by 3 strands at a speed of 0.9 ton/hour.
The water ratio of the device is 1.0, the heating steam of the ethylbenzene evaporator is 1.45 tons/hour, the circulating water consumption of the tail gas cooler is 190 tons/hour, and the energy consumption of the device is 258 kgoe/t.SM.
[ example 9 ]
The difference from the embodiment 1 is that the ethylbenzene/water separation tank separates liquid phase ethylbenzene and water, the liquid phase ethylbenzene and water enter the azeotropic heat exchanger under the control of a circulating pump, the gasification rate is 15%, and the separated gas phase ethylbenzene/water azeotrope enters the ethylbenzene supplementary evaporator in 3 strands at 2.7 tons/hour.
The water ratio of the device is 1.0, the heating steam of the ethylbenzene evaporator is 1.1 ton/hour, the circulating water consumption of the tail gas cooler is 180 ton/hour, the energy consumption of the device is 256kgoe/t.SM,
[ example 10 ]
The difference from the embodiment 1 is that the ethylbenzene/water separation tank separates liquid phase ethylbenzene and water, the liquid phase ethylbenzene and water enter the azeotropic heat exchanger under the control of a circulating pump, the gasification rate is 15%, and the separated gas phase ethylbenzene/water azeotrope enters the ethylbenzene supplementary evaporator in 3 strands at 3.6 tons/hour.
The water ratio of the device is 1.1, the heating steam of the ethylbenzene evaporator is 0.5 ton/h, the circulating water consumption of the tail gas cooler is 200 ton/h, and the energy consumption of the device is 265 kgoe/t.SM.
Comparative example 1
A10 ten thousand ton/year styrene device (8000 hours per year of operation) adopts a low water ratio azeotropic energy-saving diagram shown in a prior art 1, an independent ethylbenzene supplementation evaporation system is arranged, the flow of raw ethylbenzene is 21 ton/hour and is divided into two streams, the two streams enter an ethylbenzene/water separation tank for 14.5 ton/hour and enter an ethylbenzene supplementation evaporator for 6.5 ton/hour, the total flow of water distribution is 7.3 ton/hour, and all the streams enter the ethylbenzene/water separation tank. The weight content of water in the ethylbenzene/water separation tank is 33.4%, 145 tons/hour of separated ethylbenzene and 73 tons/hour of separated water enter an azeotropic evaporator for partial gasification. The operating pressure of the azeotropic evaporator is 100kPaA, the evaporation temperature is 91 ℃, the overhead gas of the ethylbenzene/styrene separation tower is used as a heat source, the overhead pressure is 38kPaA, the temperature is 102 ℃, and a gas-liquid mixture after partial gasification returns to the ethylbenzene/water separation tank. The ethylbenzene supplementary evaporator adopts a kettle type heat exchanger structure, raw material ethylbenzene and gas-phase ethylbenzene water azeotrope are completely gasified in a shell pass, a tube pass is heated by 0.6MPaG steam, the pressure after gasification is 100kPaA, the temperature is 132 ℃, the gasified material is mixed with a gas-phase outlet material of an ethylbenzene/water separation tank, the temperature after mixing is 104 ℃, the pressure is 98kPaA, the mixture is heated to 500 ℃ by a heater, the steam from a steam heating furnace sequentially enters a first dehydrogenation reactor, an intermediate heat exchanger and a second dehydrogenation reactor, the mass flow of the steam enters a steam heating furnace for 13.5 tons/hour, the outlet temperature of a chamber A of the steam heating furnace is 880 ℃, the outlet temperature of a chamber B of the steam heating furnace is 860 ℃, and the operating pressure of the first dehydrogenation reactor is 54 kPaA; the reaction temperature is 623 ℃, the operating pressure of the second dehydrogenation reactor is 44kPaA, and the reaction temperature is 623 ℃.
The water ratio of the device is 1.0, the ethylbenzene evaporator heats steam by 1.2 tons/hour, the ethylbenzene evaporator supplements steam by 0.56 tons/hour, the tail gas cooler circulating water consumption is 200 tons/hour, and the device energy consumption is 265 kgoe/t.SM.
Comparative example 2
A12 ten thousand ton/year styrene device (8000 hours per year of operation) adopts a low water ratio azeotropic energy-saving diagram shown in a prior art 1, an independent ethylbenzene supplementation evaporation system is arranged, the flow of raw material ethylbenzene is 24 tons/hour and is divided into two streams, the two streams enter an ethylbenzene/water separation tank for 17.8 tons/hour and enter an ethylbenzene supplementation evaporator for 6.2 tons/hour, the total flow of water distribution is 8.8 tons/hour, and all the streams enter the ethylbenzene/water separation tank. The ethylbenzene/water separation tank contained 33.1% by weight water. The operating pressure of the azeotropic evaporator is 100kPaA, the evaporation temperature is 91 ℃, the overhead gas of the ethylbenzene/styrene separation tower is used as a heat source, the overhead pressure is 36kPaA, the temperature is 101 ℃, and a gas-liquid mixture after partial gasification returns to the ethylbenzene/water separation tank. The ethylbenzene supplementary evaporator adopts a kettle type heat exchanger structure, raw material ethylbenzene and gas-phase ethylbenzene water azeotrope are completely gasified in a shell pass, a tube pass is heated by 0.6MPaG steam, the pressure after gasification is 98kPaA, the temperature is 120 ℃, the gasified material is mixed with a gas-phase outlet material of an ethylbenzene/water separation tank, the temperature after mixing is 98 ℃, the pressure is 98kPaA, the mixture is heated to 520 ℃ by a heater, the steam from a steam heating furnace sequentially enters a first dehydrogenation reactor, an intermediate heat exchanger and a second dehydrogenation reactor, the outlet temperature of a chamber A of a steam heating furnace is 878 ℃, the outlet temperature of a chamber B of the steam heating furnace is 872 ℃, and the operating pressure of the first dehydrogenation reactor is 54 kPaA; the reaction temperature is 623 ℃, the operating pressure of the second dehydrogenation reactor is 44kPaA, and the reaction temperature is 623 ℃. The water ratio of the device is 1.1, the ethylbenzene evaporator supplements 0.6 ton/h of steam, the tail gas cooler circulates 120 ton/h of water consumption, and the energy consumption of the device is 285 kgoe/t.SM.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described in relation to an exemplary embodiment, and it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.
Claims (10)
1. A raw material gasification method for preparing styrene by ethylbenzene dehydrogenation comprises the following steps:
s1: feeding a material flow VI comprising raw material ethylbenzene and raw material water into an ethylbenzene/water separation tank to obtain a liquid-phase ethylbenzene/water mixture;
s2: partially gasifying the liquid-phase ethylbenzene/water mixture through an azeotropic heat exchanger to obtain a material flow I, wherein the material flow I comprises a gas-phase ethylbenzene/water azeotropic material flow II and a gas-liquid mixture III;
s3: and feeding the raw material ethylbenzene IV and the gas-phase ethylbenzene/water azeotropic material flow II into an ethylbenzene supplementary evaporator, completely gasifying to obtain a material flow V, and feeding the material flow V into a subsequent reaction system.
2. The method according to claim 1, further comprising S4: and returning the gas-liquid mixture III to the ethylbenzene/water separation tank to obtain a gas-phase outlet material flow VII, and allowing the material flow VII to enter a subsequent reaction system, preferably, mixing the material flow V with the material flow VII to obtain a material flow VIII, and allowing the material flow VIII to enter the subsequent reaction system.
3. The process according to claim 1 or 2, characterized in that the weight percentage of raw water in stream VI is between 30 and 40%; and/or
The gasification rate of the material flow I is 4-20%; and/or
The material flow II accounts for 5-15% of the mass of the raw material ethylbenzene IV; and/or
And the mass fraction of water in the material flow V is 5-10%.
4. A process according to any one of claims 1 to 3, characterized in that the vapor phase ethylbenzene/water azeotrope stream II is fed to the ethylbenzene supplemental evaporator in a plurality of, preferably 1 to 3, passes S3.
5. The process according to any one of claims 1 to 4, wherein the feed ethylbenzene IV is present in an amount of 10-35%, preferably 12-30%, by mass of the total feed ethylbenzene; the ethylbenzene in said stream VI represents 65-90%, preferably 70-88% of the mass of the total feed ethylbenzene.
6. The process according to any one of claims 1 to 5, wherein the ethylbenzene/water separation tank is operated at a pressure of from 70 to 120kPaA and at a temperature of from 85 to 97 ℃; and/or
The operating pressure of the azeotropic heat exchanger is 70-120kPaA, and the temperature is 85-97 ℃; and/or
The operation pressure of the ethylbenzene supplementary evaporator is 80-120KPaA, and the temperature is 100-140 ℃; and/or
The pressure of the stream VIII is from 80 to 120kPaA and the temperature is from 85 to 130 ℃.
7. The process of any one of claims 1 to 6, wherein the azeotropic vaporizer uses ethylbenzene/styrene splitter overhead gas as a heat source; and/or the ethylbenzene make-up vaporizer is heated with steam.
8. A system for implementing the method according to any one of claims 1 to 7, comprising an azeotropic evaporation system, an ethylbenzene complementary evaporation system, an ethylbenzene/water separation system, a steam heating system and a dehydrogenation reaction system, wherein an ethylbenzene/water mixture partially gasified by the azeotropic evaporation system is separated into a gaseous ethylbenzene/water azeotrope stream II, the gaseous ethylbenzene/water azeotrope stream II and a raw ethylbenzene IV enter the ethylbenzene complementary evaporation system, and a stream V obtained after gasification enters the dehydrogenation reaction system for reaction.
9. The system of claim 8, wherein a gas-liquid mixture III is separated from the ethylbenzene/water mixture partially gasified by the azeotropic evaporation system, and the gas-liquid mixture III is gasified in the ethylbenzene/water separation system to obtain a gas-phase outlet stream VII, which is sent to the dehydrogenation reaction system for reaction, and preferably, the stream V and the stream VII are mixed and then sent to the dehydrogenation reaction system for reaction.
10. Use of the method according to any one of claims 1-7 or the system according to claim 8 or 9 for the dehydrogenation of ethylbenzene to styrene.
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