CN112321379B - Energy-saving and environment-friendly method for preparing ethylbenzene from dry gas - Google Patents
Energy-saving and environment-friendly method for preparing ethylbenzene from dry gas Download PDFInfo
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- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 title claims abstract description 224
- 238000000034 method Methods 0.000 title claims abstract description 48
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims abstract description 564
- 239000007789 gas Substances 0.000 claims abstract description 156
- 238000000926 separation method Methods 0.000 claims abstract description 148
- 238000010521 absorption reaction Methods 0.000 claims abstract description 115
- 239000007795 chemical reaction product Substances 0.000 claims abstract description 67
- 239000007788 liquid Substances 0.000 claims abstract description 59
- 238000005804 alkylation reaction Methods 0.000 claims abstract description 51
- 238000006243 chemical reaction Methods 0.000 claims abstract description 38
- 238000010555 transalkylation reaction Methods 0.000 claims abstract description 28
- 239000002250 absorbent Substances 0.000 claims abstract description 26
- 230000002745 absorbent Effects 0.000 claims abstract description 26
- 238000001816 cooling Methods 0.000 claims abstract description 25
- 238000010992 reflux Methods 0.000 claims abstract description 21
- 239000000047 product Substances 0.000 claims abstract description 19
- 230000029936 alkylation Effects 0.000 claims abstract description 18
- 239000000945 filler Substances 0.000 claims abstract description 14
- 239000000463 material Substances 0.000 claims abstract description 12
- 238000011084 recovery Methods 0.000 claims abstract description 12
- 239000002737 fuel gas Substances 0.000 claims abstract description 9
- 239000010692 aromatic oil Substances 0.000 claims abstract description 5
- 238000011049 filling Methods 0.000 claims abstract description 5
- 239000003054 catalyst Substances 0.000 claims description 30
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 24
- 239000005977 Ethylene Substances 0.000 claims description 24
- KVNYFPKFSJIPBJ-UHFFFAOYSA-N 1,2-diethylbenzene Chemical compound CCC1=CC=CC=C1CC KVNYFPKFSJIPBJ-UHFFFAOYSA-N 0.000 claims description 22
- 239000002994 raw material Substances 0.000 claims description 22
- 230000008569 process Effects 0.000 claims description 16
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- 238000004523 catalytic cracking Methods 0.000 claims description 3
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- ODLMAHJVESYWTB-UHFFFAOYSA-N propylbenzene Chemical compound CCCC1=CC=CC=C1 ODLMAHJVESYWTB-UHFFFAOYSA-N 0.000 description 18
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- 239000008096 xylene Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
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- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 2
- 150000001342 alkaline earth metals Chemical class 0.000 description 2
- 125000003118 aryl group Chemical group 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- IAQRGUVFOMOMEM-UHFFFAOYSA-N but-2-ene Chemical compound CC=CC IAQRGUVFOMOMEM-UHFFFAOYSA-N 0.000 description 2
- RWGFKTVRMDUZSP-UHFFFAOYSA-N cumene Chemical compound CC(C)C1=CC=CC=C1 RWGFKTVRMDUZSP-UHFFFAOYSA-N 0.000 description 2
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- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
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- 244000275012 Sesbania cannabina Species 0.000 description 1
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- 230000009471 action Effects 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
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- 229920006351 engineering plastic Polymers 0.000 description 1
- XTCQUBCCCSJAKJ-UHFFFAOYSA-N ethylbenzene Chemical compound CCC1=CC=CC=C1.CCC1=CC=CC=C1 XTCQUBCCCSJAKJ-UHFFFAOYSA-N 0.000 description 1
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- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- KOWXKIHEBFTVRU-UHFFFAOYSA-N nga2 glycan Chemical compound CC.CC KOWXKIHEBFTVRU-UHFFFAOYSA-N 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
- C07C2/54—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition of unsaturated hydrocarbons to saturated hydrocarbons or to hydrocarbons containing a six-membered aromatic ring with no unsaturation outside the aromatic ring
- C07C2/64—Addition to a carbon atom of a six-membered aromatic ring
- C07C2/66—Catalytic processes
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C6/00—Preparation of hydrocarbons from hydrocarbons containing a different number of carbon atoms by redistribution reactions
- C07C6/08—Preparation of hydrocarbons from hydrocarbons containing a different number of carbon atoms by redistribution reactions by conversion at a saturated carbon-to-carbon bond
- C07C6/12—Preparation of hydrocarbons from hydrocarbons containing a different number of carbon atoms by redistribution reactions by conversion at a saturated carbon-to-carbon bond of exclusively hydrocarbons containing a six-membered aromatic ring
- C07C6/126—Preparation of hydrocarbons from hydrocarbons containing a different number of carbon atoms by redistribution reactions by conversion at a saturated carbon-to-carbon bond of exclusively hydrocarbons containing a six-membered aromatic ring of more than one hydrocarbon
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/11—Purification; Separation; Use of additives by absorption, i.e. purification or separation of gaseous hydrocarbons with the aid of liquids
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2529/00—Catalysts comprising molecular sieves
- C07C2529/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
- C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- C07C2529/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11
- C07C2529/48—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11 containing arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
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- Water Supply & Treatment (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides an energy-saving and environment-friendly method for preparing ethylbenzene by dry gas, which mainly comprises the steps of gas-liquid separation and tail gas debenzolization of a reaction product of preparing ethylbenzene by dry gas. The method is characterized in that gas-liquid separation and tail gas absorption of a reaction product of preparing ethylbenzene from dry gas are carried out in the same tower, the absorption and separation tower is divided into four sections, the upper section of the tower is a filler section, the middle section of the tower is a tube cooling section, the lower section of the tower is a plate-type tower, and the bottom section of the tower is a tower kettle. The reaction product enters from the upper part of the tower kettle, and the absorbent enters from the top of the filling section; after the absorption and separation process of the absorption and separation tower, the tail gas is sent to a fuel gas pipe network from the top of the tower, the rich absorption liquid is mixed with condensed liquid in the reaction product, and the tail gas is sent out from the bottom flow of the tower bottom to enter the benzene tower. The noncondensable gas at the top of the benzene tower is returned to the absorption and separation tower, the circulating benzene 1 is pumped out from the upper section of the benzene tower and is sent to the alkylation reactor, the circulating benzene 2 at the bottom of the reflux tank of the benzene tower is sent to the transalkylation reactor, the material at the bottom of the benzene tower is sent to the ethylbenzene tower, the product ethylbenzene is obtained at the top of the ethylbenzene tower, the bottom liquid of the ethylbenzene tower is divided into three strands, one strand is used as an absorbent and returned to the absorption and separation tower, the other strand is sent to the transalkylation reactor, and the other strand is used as aromatic oil. The invention has simple and reliable separation flow, reduces tower equipment while fully utilizing reaction heat, saves equipment investment and subsequent operation cost, and reduces energy consumption of the device. The recovery rate of benzene carried by tail gas of the separation method is more than 99.9%, and the purity of ethylbenzene products is more than 99.8%.
Description
Technical Field
The invention provides an energy-saving and environment-friendly method for preparing ethylbenzene by dry gas, which mainly comprises the steps of gas-liquid separation and tail gas debenzolization of a reaction product of preparing ethylbenzene by dry gas. The method has simple and reliable separation flow, gas-liquid separation and tail gas absorption of the reaction products are carried out in the same tower, heat energy is fully utilized, tower equipment is reduced, equipment investment and subsequent operation cost are saved, and energy consumption of the device is reduced. The recovery rate of the tail gas carried benzene is high, the purity of the ethylbenzene product meets the requirements, and the economic benefit and the environmental benefit of a refinery are greatly improved.
Background
Ethylbenzene is an important organic chemical raw material, and is mainly used for producing styrene, so as to produce polystyrene, engineering plastics, styrene butadiene rubber and the like. In recent years, with the development of economy, the demand of China for ethylbenzene is continuously increased, the demand is in a state of supply and demand throughout the year, and more than 40% of demand dependence import is carried out every year.
Meanwhile, with the continuous development of the oil refining industry in China, a large amount of dry gas is generated as a byproduct in a refinery, and the amount of ethylene in the dry gas is considerable and is usually used as fuel or is burnt by a direct burning torch, so that huge waste of resources is caused. The technology for preparing ethylbenzene from the dry gas can effectively utilize the dry gas used as fuel to produce ethylbenzene products with high added value, which are not required in the market, and can greatly improve the economic benefit of refineries.
The technology of preparing ethylbenzene by dry gas is extended from the technology of preparing ethylbenzene by ethylene which is developed in the middle of the last century, and raw materials are changed into dilute ethylene or dry gas with lower ethylene concentration from high concentration ethylene or pure ethylene. For conventional catalytic cracking dry gases, the ethylene concentration is about 5-20%, and inert gases such as hydrogen, methane, ethane and the like account for a large part. The inert gases are mixed in the reaction product of preparing ethylbenzene by ethylene and directly enter a rectifying and separating system such as a benzene tower, so that great load is brought to the device, the gas flux in the tower is several times or even tens times higher than the gas flux to be treated under other process conditions, the liquid phase flux of the tower bottom is correspondingly increased, great energy consumption is brought, meanwhile, because the gas phase and the liquid phase are balanced, a great amount of benzene and other aromatic hydrocarbons are taken away by tail gas at the tower top, and the consumption of the benzene not only can cause economic loss, but also can bring great harm to natural environment and human health.
Therefore, compared with the technology of preparing ethylbenzene from ethylene, the technology of preparing ethylbenzene from dry gas is more interesting: how to effectively separate the gas and the liquid of the reaction product of preparing ethylbenzene from the dry gas and recycle benzene in the tail gas under the condition of not affecting the yield and the purity of the ethylbenzene product.
The separation method of the conventional process for preparing ethylbenzene from ethylene needs to cool the reaction product to normal temperature, flash-evaporating and absorbing the reaction product for two or more times under different pressures, then heating and raising the temperature, and entering a rectifying system such as a benzene tower and the like.
CN2004100211028 discloses a process flow for preparing ethylbenzene by catalyzing dry gas, the reaction product separation system of the method is a conventional separation flow, i.e. the reaction product enters a rough separation tower after heat exchange, the non-condensable gas at the top of the tower is condensed and cooled to 5-20 ℃, and enters an absorption tower, and the bottom liquid of the rough separation tower enters a benzene tower, a toluene tower, an ethylbenzene tower, a polyethylbenzene removing tower and a diethylbenzene tower to sequentially separate recycle benzene, toluene, ethylbenzene, propylbenzene, heavy components and diethylbenzene. Wherein the coarse separation tower is used for gas-liquid separation, and the absorption tower is used for recovering benzene and aromatic hydrocarbon carried by gas phase. The benzene recovery rate of the method can reach 99.5 percent.
CN2009100063071 discloses a process for preparing ethylbenzene by reacting dilute ethylene with benzene. After the gas-liquid separation of alkylation reaction products, tail gas is absorbed and discharged through a low temperature absorption and discharge device, and liquid products are sequentially separated into circulating benzene, ethylbenzene, propyl benzene, diethylbenzene and heavy components through a separation system, and diethylbenzene and benzene are returned to a transalkylation reactor for further reaction to generate ethylbenzene. In the embodiment 1, the gas-liquid separation device is a coarse separation tower, in the embodiment 2, the gas-liquid separation device is cooled by chilled water, the gas at the top of a reflux tank of the benzene tower enters a non-aromatic removal tower, the non-aromatic removal tower top is discharged without condensing gas, and the bottom material returns to the benzene tower. The purity of the ethylbenzene product of the method is 99.7%, the content of xylene is 721ppm, the total selectivity of ethylene to ethylbenzene is 99.3%, and the recovery rate of benzene carried by tail gas is 99.5%.
CN2013103576085 discloses a separation process for preparing ethylbenzene and/or propylbenzene from gas containing ethylene and/or propylene by gas phase method. In the method, the reaction product directly enters a benzene tower, the gas phase at the top of the benzene tower enters a low-temperature absorption tower, tail gas of the absorption tower is discharged from the top of the tower, and the liquid phase at the bottom of the absorption tower returns to the benzene tower. The circulating benzene is extracted from the upper part of the benzene tower, and the tower bottom material is sequentially separated into several or all of toluene, ethylbenzene, propylbenzene, diethylbenzene and high-boiling-point substances. The method has no coarse separation tower, the reaction product and inert gas are directly fed into benzene tower, and the material at the bottom of benzene tower is required to be separated into aromatic hydrocarbon components through each rectifying tower in turn. The method has no embodiment data to support the technical effects of the invention.
CN981138470 discloses a process for preparing ethylbenzene and propylbenzene by reacting dilute ethylene and propylene with benzene. The reaction product of the method directly enters a stable absorption tower, gas-liquid separation and tail gas recovery are simultaneously carried out in the stable absorption tower, the absorbent is a mixture of benzene tower and toluene tower bottom materials, or the tower bottom materials of an ethylbenzene tower and a propylbenzene tower, the tower top tail gas is used as fuel or enters a gas pipe network, and the liquid part at the tower bottom enters each rectifying tower to sequentially separate benzene, toluene, ethylbenzene, propylbenzene and polyalkylbenzene. The ethylbenzene purity of the method is 99.7%, the total selectivity of ethylbenzene produced by ethylene with the xylene content of 945ppm is 99%, and the recovery rate of benzene carried by tail gas is not shown.
The invention provides an energy-saving and environment-friendly method for preparing ethylbenzene from dry gas. According to the invention, the reaction product of preparing ethylbenzene from dry gas enters an absorption separation tower after heat exchange, so that gas-liquid separation and absorption and benzene removal of tail gas are realized. The absorption separation tower is divided into four sections, wherein the upper section of the tower is a filler section, the middle section of the tower is a tubular cooling section, the lower section of the tower is a plate-type tower, and the bottom section of the tower is a tower kettle. After the alkylation reaction product enters the absorption separation tower, the absorption separation tower is subjected to four processes, namely flash evaporation, depressurization and cooling, gas-liquid fractionation separation of a plate tower section, cooling condensation of a tube array cooling section and absorption and liquid removal of tail gas. The invention fully utilizes the reaction heat, can effectively separate gas from liquid of the reaction product of preparing ethylbenzene from dry gas under the condition of not influencing the yield and purity of the ethylbenzene product, and recovers benzene in tail gas.
The invention reduces a crude separation tower, a tail gas benzene absorption tower and subsequent aromatic hydrocarbon rectifying towers, directly circulates aromatic hydrocarbon except ethylbenzene to a reaction system, further generates alkylation reaction and transalkylation reaction, saves equipment investment and subsequent operation cost, and improves the yield of ethylbenzene.
Disclosure of Invention
The invention provides an energy-saving and environment-friendly method for preparing ethylbenzene by dry gas, which mainly comprises the steps of gas-liquid separation and tail gas debenzolization of a reaction product of preparing ethylbenzene by dry gas. Specifically, the gas-liquid separation and tail gas absorption of the reaction product of ethylbenzene prepared from dry gas are carried out in the same tower, so that the reaction heat is fully utilized, the coarse separation tower equipment and the subsequent aromatic hydrocarbon rectifying towers are reduced, and the aromatic hydrocarbons except the ethylbenzene are directly recycled to the reaction system. The ethylbenzene product of the invention meets the requirement of purity, the recovery rate of the tail gas carried benzene is high, and the economic benefit and the environmental benefit of a refinery are greatly improved.
The invention provides an energy-saving and environment-friendly method for preparing ethylbenzene by using dry gas, which comprises the following steps:
(1) After propylene is removed from raw material dry gas through pretreatment, the raw material dry gas enters the reactor from the position between the top of the alkylation reactor and the catalyst bed layer in a segmented manner;
(2) The alkylation reaction product of the dry gas for preparing ethylbenzene enters an absorption separation tower after heat exchange, the tower is divided into four sections, the upper section of the tower is a filler section, the middle section of the tower is a tubular cooling section, the lower section of the tower is a plate-type tower section, and the bottom section of the tower is a tower kettle section;
(3) The alkylation reaction product enters from the upper part of a tower bottom of the absorption separation tower, the absorbent enters from the top of the filler section, after the absorption and separation processes, tail gas enters a fuel gas pipe network from the top of the tower, the rich absorption liquid is mixed with condensed liquid of the reaction product, and the mixture enters a benzene tower after flowing out from the bottom of the tower bottom;
(4) Adding normal-temperature fresh benzene from a benzene tower reflux tank, returning noncondensable gas of the benzene tower to an absorption separation tower, extracting circulating benzene 1 from the upper section of the benzene tower, leading the circulating benzene 1 to an alkylation reactor, dividing the circulating benzene 1 into circulating hot benzene and circulating cold benzene, respectively leading the circulating benzene 2 at the bottom of the benzene tower reflux tank to a transalkylation reactor from the top of the reactor, leading materials at the bottom of the benzene tower to an ethylbenzene tower, obtaining ethylbenzene at the top of the ethylbenzene tower, leading bottom liquid of the ethylbenzene tower to polyethylbenzene mainly containing diethylbenzene, dividing the polyethylbenzene into three strands, leading one strand to aromatic oil, leading the one strand to the absorption separation tower as an absorbent after being pressurized and cooled, and leading the one strand to the transalkylation reactor;
(5) The circulating benzene 2 at the bottom of the benzene tower reflux tank and polyethylbenzene at the bottom of the ethylbenzene tower are fed from the bottom of the transalkylation reactor, and the transalkylation reaction product flowing out of the top of the reactor is directly fed into the benzene tower to participate in the subsequent separation process.
In the invention, the gas-liquid separation and tail gas absorption and benzene removal of the reaction product of the ethylbenzene prepared from the dry gas are carried out in the same tower. The absorption separation tower is divided into four sections, wherein the upper section of the tower is a filler section, the middle section of the tower is a tubular cooling section, the lower section of the tower is a plate-type tower section, and the bottom section of the tower is a tower kettle section.
The reaction product from the alkylation reactor contains dry gas, benzene, ethylbenzene, diethylbenzene and a small amount of polyethylbenzene, and the alkylation reaction product enters an absorption separation tower after heat exchange. In the absorption separation tower, the absorbent enters from the top of the filler section and is in countercurrent contact with the reaction tail gas at low temperature, most of benzene in the reaction tail gas is absorbed to finish the benzene removal of the tail gas, then the tail gas is removed from the top of the tower to form a fuel gas pipe network, and the rich absorption liquid flows downwards through a tube cooling section, a plate tower section and a tower kettle section of the absorption separation tower and sequentially passes through condensation cooling separation, gas-liquid fractionation separation and flash evaporation separation, and the liquid phase flows out from the bottom of the absorption separation tower and goes to a subsequent separation system.
The upper section of the absorption separation tower is a filler section, the absorbent at the top of the filler is cold polyethylbenzene, the absorbent flows downwards and contacts with ascending tail gas in a countercurrent way, the absorption and the benzene removal of the tail gas are completed, and the tail gas is discharged from the tower from the top. The middle section of the tower is a tube cooler, the cooling medium is circulating water or other refrigerants, and the materials are separated while being condensed and cooled. The lower section of the tower is a plate section, and the gas-liquid fractionation separation is completed under the action of the tower plate and the bottom reboiler. The bottom section is a tower kettle section, and a reboiler is arranged at the bottom of the tower to finish flash evaporation and reboiling.
In a word, after the alkylation reaction product enters the absorption separation tower, the absorption separation tower is subjected to four processes, namely flash evaporation, depressurization and cooling, gas-liquid fractionation separation of a plate tower section, cooling condensation of a tube array cooling section, reflux for the plate tower section and absorption and liquid removal of tail gas.
In the invention, the alkylation reaction product exchanges heat with circulating benzene 1 extracted from the upper section of the benzene tower and then enters an absorption and separation tower, the temperature of the absorption and separation tower is gradually reduced from bottom to top, the reaction product contacts with an absorbent, and gas-liquid separation and tail gas absorption are completed section by section. The invention combines the characteristics of the separation modes of each section, and fully utilizes the heat brought by the reaction products.
In the invention, circulating benzene 1 is pumped out from the upper section of the benzene tower and is sent to an alkylation reactor, the circulating benzene 1 is divided into circulating hot benzene and circulating cold benzene, the circulating hot benzene enters the reactor from the position between the top of the reactor and a catalyst bed layer in a segmented way, the circulating hot benzene indirectly utilizes the reaction heat, the reaction feed is preheated, and the circulating cold benzene can control the temperature rise of the catalyst bed layer to obtain the ideal alkylation reaction temperature.
In the invention, the normal-temperature fresh benzene is directly injected into the benzene top reflux tank, so that the cold quantity of the fresh benzene is fully utilized, and the energy is saved.
The raw material dry gas mainly refers to catalytic cracking dry gas, thermal cracking, MTO dry gas, MTP dry gas and other alkene-containing gas generated in the secondary petroleum processing or coal processing process, and the concentration of ethylene in the dry gas composition is 5% -95% (V).
In the invention, the alkylation reaction adopts gas phase reaction, and the reaction product enters an absorption separation tower after heat exchange; the alkyl transfer reaction adopts liquid phase reaction, and the reaction product directly enters a benzene tower and a subsequent separation system.
In the step (2) and the step (3), the temperature of the alkylation reaction product entering the absorption and separation tower after heat exchange is 150-200 ℃, and the feeding position is the upper part of the tower kettle of the absorption and separation tower.
In the step (4), after the non-condensable gas at the top of the benzene tower is mixed with the alkylation reaction product, the non-condensable gas returns to the absorption separation tower from the upper part of the tower kettle to remove benzene.
In the step (3) and the step (4), the temperature of the absorbent entering the absorption and separation tower is 0-30 ℃, the pressure is 2.0-4.5 MPa, and the feeding position is the top of the filling section of the absorption and separation tower. In the invention, the absorbent of the absorption and separation tower is the bottom liquid of the ethylbenzene tower.
The operation pressure of the absorption and separation tower is 0.2-1.0 MPa, the temperature of the tower top is 0-50 ℃, and the temperature of the tower bottom is 80-150 ℃.
The invention can obtain ideal separation effect and tail gas benzene recovery rate by adjusting the dosage and temperature of the absorbent of the absorption separation tower, the dosage and temperature of the circulating water in the middle section of the absorption separation tower, the temperature of the reboiler in the corresponding absorption separation tower kettle, and the like.
In the invention, aromatic hydrocarbon except ethylbenzene is recycled back to the reaction system: circulating benzene 1 extracted from the upper section of the benzene tower is sent to an alkylation reactor, circulating benzene 2 at the bottom of a reflux tank of the benzene tower is sent to a transalkylation reactor and is used as raw materials of alkylation reaction and transalkylation reaction, and the reaction is continued to generate target product ethylbenzene; the bottom liquid of the ethylbenzene tower is divided into three strands, one strand is used as an absorbent and returned to the absorption separation tower, the other strand is used as a raw material of the transalkylation reaction and sent to the transalkylation reactor, and the other strand is used for obtaining aromatic hydrocarbon oil.
The benzene tower has the operating pressure of 1.0-2.5 MPa and the operating temperature of 150-250 ℃; the operating pressure of the ethylbenzene column is 1.0-2.5 MPa, and the operating temperature is 200-350 ℃.
The invention can make the benzene bottom oil free of benzene by adjusting the temperature of the reboiler at the bottom of the benzene tower, adjust the amount and temperature of the reflux at the top of the ethylbenzene tower, and the like, so that the top of the ethylbenzene tower does not contain diethylbenzene, thereby obtaining ideal ethylbenzene product purity.
In order to obtain the desired ethylbenzene yield and ethylbenzene purity, the raw dry gas needs to be pretreated for removal of propylene and other deleterious impurities that can produce cumene. In the reaction part of the process for preparing ethylbenzene by dry gas, the invention is mainly characterized in that:
(1) The alkylation reaction adopts gas phase reaction, the reaction temperature is 360-400 ℃, the reaction pressure is 0.7-1.2 MPa, the weight ratio of benzene to ethylene is 10-20, and the weight hourly space velocity of ethylene is 0.2-1.0h -1 。
(2) The transalkylation reaction adopts liquid phase reaction, the reaction temperature is 150-250 ℃, the reaction pressure is 2.5-3.5 MPa, the weight ratio of benzene to polyethylbenzene is 1-10, and the weight hourly space velocity of polyethylbenzene is 0.1-5.0 h -1 。
(3) The alkylation reaction of ethylene and benzene in the raw material dry gas is a strong exothermic reaction, and in order to control the reaction temperature rise, the raw material cold dry gas and circulating cold benzene enter the reactor from between catalyst beds in a sectional feeding mode, so that the purposes of preheating the raw material, reducing the reaction heat effect and adjusting the temperature of the catalyst beds are achieved.
(4) The catalyst may be a commercially available alkylation catalyst or transalkylation catalyst, more preferably a novel catalyst developed by Beijing Hui Er Sanji green chemical Co., ltd.): WJH series alkylation catalyst and WJZY series transalkylation catalyst. The two novel catalysts are ZSM-5 molecular sieve catalysts jointly modified by alkaline earth metal, rare earth element and VA group element compounds, wherein the alkaline earth metal content is 2-10% (wt), the rare earth element content is 2-10% (wt) and the VA group element content is 3-15% (wt). The molecular sieve and the alumina binder are used together as a carrier of metal, and the metal is carried on the catalyst by adopting an impregnation method.
The shaping process of the catalyst is known to the person skilled in the art, such as extrusion, tabletting, spheronization, drop balls. Mixing molecular sieve, aluminum hydroxide, sesbania powder, etc. and adding proper amount of water and acid (hydrochloric acid, nitric acid or acetic acid), extruding and kneading, extruding, drying and breaking into strips, or extruding and rounding into balls; or mixing all the raw materials to obtain colloid, and dripping into hot oil or oil ammonia bath to obtain ball shape. Drying the formed catalyst at the room temperature to 150 ℃, depositing metal on the catalyst by a metal soluble salt (generally nitrate) impregnation method after drying, and roasting for 1 to 24 hours in air and/or steam atmosphere at the temperature of 400 to 700 ℃ to obtain the catalyst.
In summary, the invention provides an energy-saving and environment-friendly method for preparing ethylbenzene from dry gas, which mainly comprises the steps of gas-liquid separation and tail gas debenzolization of reaction products of preparing ethylbenzene from dry gas. The gas-liquid separation and tail gas absorption and benzene removal of the reaction product of the ethylbenzene preparation from the dry gas are carried out in the same tower, the absorption and separation tower is divided into four sections, the upper section of the tower is a filler section, the middle section of the tower is a tube cooling section, the lower section of the tower is a plate-type tower, and the bottom section of the tower is a tower kettle. After the alkylation reaction product enters the absorption separation tower after heat exchange, the absorption separation tower is subjected to four processes, namely flash evaporation, depressurization and cooling, gas-liquid fractionation separation of a plate tower section, cooling condensation of a tube cooling section and absorption and liquid removal of tail gas. The absorption and separation tower fully utilizes the heat energy of the reaction product, can effectively separate the gas from the liquid of the reaction product of preparing ethylbenzene from dry gas under the condition of not affecting the yield and purity of the ethylbenzene product, and can recycle benzene in tail gas.
The invention reduces the subsequent aromatic hydrocarbon rectifying towers such as a rough separation tower, a tail gas benzene absorption tower, a toluene tower, a diethylbenzene tower, a propylbenzene tower and the like, directly circulates aromatic hydrocarbon except ethylbenzene into a reaction system, and further generates alkylation reaction and transalkylation reaction to generate ethylbenzene as a target product.
The invention has the following effects:
(1) The invention converts the dry gas used as fuel into ethylbenzene with high added value, fully utilizes the reaction heat, simplifies the tower equipment, reduces the energy consumption of the device, improves the benzene recovery rate of tail gas, and has obvious economic benefit and positive environmental benefit.
(2) The alkylation reaction of ethylene and benzene in the dry gas is a strong exothermic reaction, and the raw material cold dry gas and circulating cold benzene enter the alkylation reactor from between catalyst beds in a sectional feeding mode, so that the reaction heat effect is reduced, the reaction temperature rise is controlled, the reaction heat is fully utilized, and the purposes of preheating the reaction feed and adjusting the temperature of the catalyst beds are achieved.
(3) The invention fully utilizes the heat brought by the reaction product to make the alkylation reaction product exchange heat with the circulating benzene 1 extracted from the upper section of the benzene tower, thereby achieving the purpose of preheating the alkylation reaction feed.
(4) The alkylation reaction product of the invention directly enters an absorption separation tower after primary heat exchange; the temperature of the absorption separation tower is gradually reduced from bottom to top, the alkylation reaction product is contacted with the absorbent, and the gas-liquid separation and the absorption and benzene removal of tail gas are completed gradually. The invention combines the characteristics of the separation modes of each section, and fully utilizes the heat brought by the reaction products.
(5) In the invention, the normal-temperature fresh benzene is directly injected into the reflux tank at the top of the benzene tower, so that the cold quantity of the fresh benzene is fully utilized, and the energy is saved.
(6) In the invention, the gas-liquid separation and tail gas absorption and benzene removal of the alkylation reaction product are carried out in the same tower, and all aromatic hydrocarbons except ethylbenzene are recycled back to the reaction system, so that the coarse separation tower equipment and the subsequent aromatic hydrocarbon rectifying towers are reduced, and the equipment investment and the subsequent operation cost are saved.
(7) According to the absorption separation tower and the separation method provided by the invention, the purity of the obtained ethylbenzene product is more than 99.8%, and the recovery rate of the tail gas carried benzene is not less than 99.9%.
Drawings
FIG. 1 is a schematic view of the structure of an absorption separation column of the present invention, n being the number of trays in a tray column section.
As shown in FIG. 1, the absorption separation tower is divided into four sections, wherein the upper section of the tower is a filler section, the middle section of the tower is a tube cooling section, the lower section of the tower is a plate tower, and the bottom section of the tower is a tower kettle. The absorbent enters from the top of the filling section, the alkylation reaction product enters from a feed inlet at the upper part of the tower bottom of the absorption separation tower, and after four-section gas-liquid separation in the tower and tail gas absorption and benzene removal, the tail gas without benzene goes to a fuel gas pipe network from the top of the tower, and the liquid flows out from the bottom of the tower bottom and then enters into a subsequent separation system.
FIG. 2 is a schematic process flow diagram of the method of the present invention, but the present invention is not limited thereto.
The process flow of the method shown in fig. 2 is as follows:
the raw material dry gas enters an alkylation reactor in a segmented way after being pretreated, circulating benzene 1 is extracted from the upper section of a benzene tower and is divided into circulating hot benzene and circulating cold benzene, the circulating hot benzene and the circulating cold benzene enter the reactor respectively from the position between the top of the reactor and a catalyst bed layer, reaction products flow out from the bottom of the alkylation reactor, exchange heat with the circulating benzene 1 extracted from the upper section of the benzene tower, and enter from the upper part of a tower bottom of an absorption separation tower.
The absorbent enters from the top of the filling section of the absorption separation tower, after the absorption and separation processes, tail gas enters a fuel gas pipe network from the top of the tower, rich absorption liquid is mixed with condensed liquid in reaction products, and the mixture flows out from the bottom flow of the tower bottom to enter the benzene tower.
Fresh benzene at normal temperature is added from a reflux tank at the top of a benzene tower, noncondensable gas at the top of the benzene tower returns to an absorption separation tower to remove benzene, circulating benzene 1 is pumped out from the upper section of the benzene tower and is sent to an alkylation reactor, circulating benzene 2 at the bottom of the reflux tank of the benzene tower is sent to a transalkylation reactor, materials at the bottom of the benzene tower enter an ethylbenzene tower, ethylbenzene is obtained at the top of the ethylbenzene tower, bottom liquid of the ethylbenzene tower is divided into three strands, one strand is used as an absorbent and returns to the absorption separation tower, the other strand is sent to the transalkylation reactor, and aromatic hydrocarbon oil is obtained.
The circulating benzene 2 at the bottom of the benzene tower reflux tank and polyethylbenzene at the bottom of the ethylbenzene tower are fed from the bottom of the transalkylation reactor, and the transalkylation reaction product flowing out of the top of the reactor is directly fed into the benzene tower to participate in the subsequent separation process.
Detailed Description
The present invention will be further described with reference to examples, but the present invention is not limited thereto.
Raw material specification
(1) The dry gas of the raw material comes from an MTP device of a certain plant of Hami in Xinjiang, and the composition of the dry gas is shown in a table 1; the raw material benzene is commercially available petroleum pure benzene, and the main properties are shown in Table 2.
(2) Alkylation catalyst: model WJH-31, the appearance is strip-shaped with a butterfly section of 1.8mm multiplied by 3.2mm, and the length is 3-10 mm. Transalkylation catalyst: model WJZY-3 is strip-shaped with a butterfly section of 1.8mm multiplied by 3.2mm, and the length is 3-10 mm. Both catalysts were supplied by the company of Beijing Hui Er Sanji green chemical technology.
Example 1
This example was performed on an 8 ten thousand tons/year dry gas ethylbenzene plant from Xinjiang Hami plant using the absorption and separation column shown in FIG. 1 and the process flow shown in FIG. 2.
After the propylene is removed by pretreatment of the raw material MTP dry gas, the raw material MTP dry gas enters an alkylation reactor in a segmented way. Circulating hot benzene pumped from the upper section of the benzene column enters from the top of the reactor, and the feeding temperature is high360 ℃ and the pressure is 1.0MPa. Circulating cold benzene pumped from the upper section of the benzene tower enters from the position between the catalyst beds, and the feeding temperature is 200 ℃ and the pressure is 1.2MPa. The alkylation reaction temperature is 360-400 ℃, the reaction pressure is 1.0MPa, the weight ratio of benzene to ethylene is 15, and the weight hourly space velocity of ethylene is 0.8h -1 。
After exchanging heat with circulating benzene 1 extracted from the upper section of the benzene tower, the temperature is reduced to 150-180 ℃, and the product enters the absorption separation tower from the upper part of the tower kettle. The absorbent from the bottom of the ethylbenzene column is cooled to 15 ℃ and the pressure is 2.5MPa, and enters the absorption separation column from the upper part of the packing section. The pressure of the dry gas tail gas at the top of the tower is controlled by a regulating valve, and the dry gas tail gas enters a fuel gas pipe network. The bottom liquid at 90 ℃ enters a benzene tower.
Fresh benzene at normal temperature is directly added into a benzene tower top reflux tank. The steam at the top of the benzene tower is cooled to 200 ℃ and the pressure is 1.5MPa, and then enters a reflux tank at the top of the benzene tower. The noncondensable gas at the top of the benzene tower flows out from the top of the reflux tank and returns to the absorption separation tower to remove benzene. The material at the bottom of the reflux tank at the top of the benzene column is divided into two parts, one part is refluxed to the benzene column, and the other part is used as a circulating benzene 2 dealkylation transfer reactor. The circulating benzene 1 is extracted from a fifth column plate below the top of the column and is divided into circulating hot benzene and circulating cold benzene, and enters the alkylation reactor from the position between the top of the reactor and the catalyst bed layer in a sectional manner. The benzene bottom liquid enters an ethylbenzene column.
The ethylbenzene column is a plate column with 100 layers of plates. The feeding temperature of the ethylbenzene column is 300 ℃ and the pressure is 1.4MPa. The temperature of the top of the ethylbenzene column is 220 ℃ and the pressure is 1.0MPa, thus obtaining the ethylbenzene product. The temperature of the bottom of the ethylbenzene tower is 240 ℃ and the pressure is 1.2MPa, and the ethylbenzene tower is divided into three streams, one stream is pressurized and cooled and then is returned to the absorption separation tower as an absorbent, and the other stream is sent to the transalkylation reactor, and aromatic hydrocarbon oil is obtained.
The transalkylation reactor is fed from the bottom and the reaction product flows out from the top. The transalkylation reaction temperature is 220 ℃, the reaction pressure is 3.0MPa, the weight ratio of the recycle benzene 2 to the polyethylbenzene is 5, and the weight hourly space velocity of the polyethylbenzene is 2.0h -1 . The reaction product directly enters the benzene tower.
The reaction was continued for 30 days with a daily card feed balance, see Table 3, where crude propylene was from the feed dry gas pretreatment section and aromatic oil from the ethylbenzene column bottom. And taking the gas at the top of the absorption separation tower to measure the benzene content, wherein the benzene recovery rate of tail gas is 99.8%. The ethylbenzene product was collected for quality analysis, and the ethylbenzene purity was 99.7% to the petrochemical standard SH/T1140-2001, see Table 4.
TABLE 1 composition of raw material dry gas
| Component (A) | Volume percent, percent |
| Hydrogen gas | 16.25 |
| Methane | 28.21 |
| Ethane (ethane) | 5.9 |
| Ethylene | 48.25 |
| Propane | 0.12 |
| Propylene | 0.77 |
| Butane | 0.2 |
| Butene (B) | 0.3 |
| Totals to | 100 |
TABLE 2 principal Properties of raw benzene
| Project | Unit (B) | Index (I) |
| Benzene content | wt | ≥99.9％ |
| Toluene content | wt | ≤0.05％ |
| Sulfur content | ppm | ≤0.5 |
| Nitrogen content | ppm | ≤1.0 |
| Chromaticity of | ≤20 | |
| Freezing point | ℃ | 5.4 |
| Boiling point of | ℃ | 80 |
| Density of | kg/m 3 | 879 |
| Latent heat of gasification | kcal/kg | 94 |
| Molecular weight | g/mol | 78 |
Table 3 material balance table
| Project | Flow, t/h |
| Raw materials | |
| MTP dry gas | 4.00 |
| Benzene | 7.152 |
| Product(s) | |
| Ethylbenzene (ethylbenzene) | 9.597 |
| Crude propylene | 0.12 |
| Aromatic oil | 0.156 |
| Tail gas | 1.280 |
TABLE 4 specification sheet for ethylbenzene products
| Project | Unit (B) | Index (I) |
| Ethylbenzene content | wt | ≥99.5％ |
| Xylene content | wt | ≤0.15％ |
| Content of propylbenzene | wt | ≤0.03 |
| Diethylbenzene content | ppm | 10 |
| Sulfur content | ppm | ≤3 |
| Freezing point | ℃ | |
| Boiling point of | ℃ | 136 |
| Density of | kg/m 3 | 867 |
| Latent heat of gasification | kcal/kg | 460 |
| Molecular weight | g/mol | 106 |
Claims (16)
1. The method for preparing ethylbenzene by using energy-saving and environment-friendly dry gas mainly comprises the following steps of gas-liquid separation and tail gas debenzolization of a reaction product of preparing ethylbenzene by using the dry gas:
(1) After propylene is removed from raw material dry gas through pretreatment, the raw material dry gas enters the reactor from the position between the top of the alkylation reactor and the catalyst bed layer in a segmented manner;
(2) The alkylation reaction product of the dry gas for preparing ethylbenzene enters an absorption separation tower after heat exchange, the tower is divided into four sections, the upper section of the tower is a filler section, the middle section of the tower is a tubular cooling section, the lower section of the tower is a plate-type tower section, and the bottom section of the tower is a tower kettle section;
(3) The alkylation reaction product enters from the upper part of a tower bottom of the absorption separation tower, the absorbent enters from the top of the filler section, after the absorption and separation processes, tail gas enters a fuel gas pipe network from the top of the tower, the rich absorption liquid is mixed with condensed liquid in the reaction product, and the mixture enters a benzene tower after flowing out from the bottom of the tower bottom;
(4) Adding normal-temperature fresh benzene from a benzene tower reflux tank, returning noncondensable gas of the benzene tower to an absorption separation tower, extracting circulating benzene 1 from the upper section of the benzene tower, leading the circulating benzene 1 to an alkylation reactor, dividing the circulating benzene 1 into circulating hot benzene and circulating cold benzene, respectively leading the circulating benzene 2 at the bottom of the benzene tower reflux tank to a transalkylation reactor from the top of the reactor and the catalyst bed, leading materials at the bottom of the benzene tower to an ethylbenzene tower, obtaining ethylbenzene at the top of the ethylbenzene tower, leading bottom liquid of the ethylbenzene tower to be polyethylbenzene mainly containing diethylbenzene, dividing the polyethylbenzene into three strands, leading one strand to obtain aromatic oil, leading the one strand to be used as an absorbent to be returned to the absorption separation tower, and leading the one strand to the transalkylation reactor;
(5) The circulating benzene 2 at the bottom of the benzene tower reflux tank and polyethylbenzene at the bottom of the ethylbenzene tower are fed from the bottom of the transalkylation reactor, and the transalkylation reaction product flowing out of the top of the reactor is directly fed into the benzene tower to participate in the subsequent separation process.
2. The absorption and separation tower for the reaction product gas-liquid separation and tail gas benzene removal of the ethylbenzene prepared from dry gas is characterized in that the absorption and separation tower is divided into four sections, wherein the upper section of the tower is a filler section, the middle section of the tower is a tube cooling section, the lower section of the tower is a plate-type tower section, and the bottom section of the tower is a tower kettle section; the alkylation reaction product enters from the upper part of the tower kettle, the absorbent enters from the top of the filling section, after gas-liquid separation and tail gas debenzolization, the debenzolized tail gas goes to a fuel gas pipe network from the tower top, and the benzene-rich liquid phase flows out from the tower bottom.
3. The absorption and separation tower according to claim 2, wherein in the absorption and separation tower, the absorbent enters from the top of the filler section and is in countercurrent contact with the reaction tail gas at low temperature, most of benzene in the reaction tail gas is absorbed, the benzene removal of the tail gas is completed, the tail gas is removed from the tower top to the fuel gas pipe network, the rich absorption liquid flows downwards through the tube cooling section, the plate tower section and the tower bottom section of the absorption and separation tower, and the liquid phase flows out from the bottom of the absorption and separation tower to the subsequent separation system through condensation cooling separation, gas-liquid fractionation separation and flash evaporation separation in sequence.
4. The process according to claim 1, wherein the gas-liquid separation of the reaction product and the absorption of the tail gas are carried out in the same column; after the alkylation reaction product enters the absorption separation tower, the absorption separation tower is subjected to four processes, namely flash evaporation, depressurization and cooling, gas-liquid fractionation separation of a plate tower section, cooling condensation of a tube array cooling section and absorption and liquid removal of tail gas.
5. The method of claim 1, wherein the alkylation reaction product exchanges heat with the circulating benzene 1 extracted from the upper section of the benzene tower and then enters an absorption and separation tower, the temperature of the absorption and separation tower is gradually reduced from bottom to top, the reaction product is contacted with an absorbent, the gas-liquid separation and the absorption and the debenzolization of tail gas are completed in a section-by-section manner, and the heat brought by the reaction product is fully utilized.
6. The method according to claim 1, wherein in the step (4), circulating benzene 1 is pumped out from the upper section of the benzene tower and is sent to the alkylation reactor, the circulating benzene 1 is divided into circulating hot benzene and circulating cold benzene, and the circulating benzene and the circulating cold benzene enter the reactor from the position between the top of the reactor and the catalyst bed layer respectively, and the purposes of preheating raw materials, reducing the reaction heat effect, controlling the reaction temperature rise and adjusting the temperature of the catalyst bed layer are achieved by utilizing the characteristic that the alkylation reaction is a strong exothermic reaction.
7. The method according to claim 1, wherein the raw dry gas mainly comprises catalytic cracking dry gas, thermal cracking, MTO dry gas, MTP dry gas and other olefin-containing gases generated in the secondary petroleum processing or coal processing process, and the ethylene concentration in the dry gas composition is 5% -95% (V).
8. The method according to claim 1, wherein in the step (2) and the step (3), the temperature of the alkylation reaction product entering the absorption separation tower after heat exchange is 150-250 ℃, and the feeding position is the upper part of the tower bottom of the absorption separation tower.
9. The process of claim 1 wherein in step (4) the non-condensable gases are mixed with the alkylation reaction product and returned to the absorber separation column from the top of the column vessel to debenzolize the non-condensable gases.
10. The method according to claim 1, wherein in the step (3) and the step (4), the temperature of the absorbent entering the absorption separation column is 0-30 ℃, the pressure is 2.0-4.5 MPa, and the feeding position is the top of the packing section of the absorption separation column.
11. The method of claim 1, wherein the middle section of the absorption separation tower is a tube array cooling section, and the cooling medium is circulating water or other refrigerant.
12. The method according to claim 1, wherein a bottom reboiler is provided at the bottom of the absorption separation column.
13. The process according to claim 1, wherein the absorption separation column is operated at a pressure of 0.2 to 1.0MPa, a column top temperature of 0 to 50℃and a column bottom temperature of 80 to 150 ℃.
14. The method according to claim 1, wherein the desired separation effect and benzene recovery from the tail gas can be obtained by adjusting the amount and temperature of the absorbent in the absorption separation column, the amount and temperature of the circulating water in the middle section of the absorption separation column, and the temperature of the reboiler in the bottom of the absorption separation column.
15. The process of claim 1, wherein the benzene column is operated at a pressure of 1.0 to 2.5MPa and a temperature of 150 to 250 ℃; the operating pressure of the ethylbenzene column is 1.0-2.5 MPa, and the operating temperature is 200-350 ℃.
16. The process of claim 1, wherein the desired separation and ethylbenzene product purity is achieved by adjusting the temperature of the reboiler at the bottom of the benzene column and the amount and temperature of the ethylbenzene column overhead reflux.
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| CN1252400A (en) * | 1999-08-27 | 2000-05-10 | 中国石油天然气集团公司 | Combined catalytic rectification and absorption process of preparing alkyl arene through the reaction of low-density olefine and arene |
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Denomination of invention: An energy-saving and environmentally friendly method for producing ethylbenzene from dry gas Granted publication date: 20230509 Pledgee: Urumqi Bank Co.,Ltd. Hami Branch Pledgor: Beijing Huiersanji Green Chem-Tech Co.,Ltd. Registration number: Y2024980011873 |