CN103073383B - Method and device for separating isohexane, n-hexane and benzene - Google Patents
Method and device for separating isohexane, n-hexane and benzene Download PDFInfo
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Abstract
The invention relates to a method and device for separating isohexane, n-hexane and benzene. A rectifying and extractive distillation combined method is adopted. The device comprises a light component removing unit, a hexane extractive distillation unit, a hexane separating unit, a first solvent recovery unit, a benzene extractive distillation unit, a second solvent recovery unit and a solvent regenerating unit. Impurities with boiling point lower than that of 2-methyl pentane are firstly removed from the mixed hydrocarbon raw materials, such as raffinate oil, pyrolysis gasoline, straight distilling gasoline, from an aromatics extraction device, and then an extractive distillation method is adopted for separating the mixed hexane without benzene; the mixed hexane is further separated into an isohexane product and a n-hexane product; the material separated from the mixed hexane is separated by adopting the extractive distillation method, so that a benzene product is obtained; the total mass fraction of the isohexane product 2-methyl pentane and 3-methyl pentane is not less than 95% and the benzene content is less than 100ppm; and the n-hexane product meets the national standard GB16629-2008 and the mass fraction is not less than 99%.
Description
Technical field
The present invention relates to separation method and the equipment of a kind of isohexane, normal hexane and benzene, particularly the separation method that combines of a kind of conventional distillation and extracting rectifying.
Background technology
Normal hexane is a kind of colourless transparent liquid, is one of varsol of widespread use, is the representational non-polar solvent of most.Industrial hexane solvent oil can be used in the industries such as medicine, chemical industry, macromolecular material, rubber industry and food.As edible oil industrial extractant, require that hexane solvent oil distillate is more narrow better, simultaneously benzene content is more low better, and these two indexs directly have influence on the quality of edible oil, oil yield and energy consumption etc.When normal hexane is used as the solvent of propylene polymerization, require that benzene content is more few better.This is not only conducive to the speed improving polypropylene polymerization, and is also beneficial to the polyacrylic quality of guarantee.In addition, highly purified normal hexane Ye Shi assay laboratory carries out scientific research, one of important organic solvent of analytical test.The market demand of the high-end normal hexane product of high purity, low benzene content is very large.
Isohexane main component is 2-methyl-pentane and 3-methyl-pentane, and as short-side chain varsol with its lower boiling, narrow boiling range, gasification latent heat is low and more and more do not favored in edible oil industry in the advantage such as row of polluted air objectionable impurities.As edible oil extraction agent, the benzene content in isohexane product has strict demand equally.
Hexane is produced normal catalytic reforming generation oil, hydrogenated pyrolysis gasoline or the Aromatic raffinate of adopting and is made raw material.In these raw materials, often component is various, there are alkane, naphthenic hydrocarbon, aromatic hydrocarbons and a small amount of alkene, have again multiple isomers in every class component, and the boiling point between these compound things differ very little, what have also can form azeotropic, as lower than normal hexane boiling point in 3-methylpentane 5.4 DEG C; Methylcyclopentane is higher than normal hexane boiling point 3.1 DEG C; Normal hexane and benzene can form minimum azeotropic mixture.This minimum azeotropic mixture not only can cause benzene in normal hexane product to be difficult to remove, and benzene in isohexane product also can be caused to be difficult to remove.As can be seen here, production high purity normal hexane, not containing benzene isohexane only by conventional distillation method be separated can not realize.
The technique that rectifying and hydrogenation combine is one of main method of producing hexane at present.The scheme that usual rectifying and hydrogenation produce normal hexane has two kinds, is rectifying after first rectifying repeated hydrogenation and first hydrogenation respectively.Current, although to be separated the method obtaining thick normal hexane quite ripe for the double tower concentrated from straight run or raffinate oil middle rectificating method or platformate raffinate hydrogenation, its purity is all 60% ~ 90%.But the production technique of domestic current normal hexane and output all cannot meet the demand of industrial market, and high purity normal hexane relies on import substantially.Therefore, improve normal hexane production technique, the production technology of exploitation high purity normal hexane is significant.
The method of employing shortening removes the benzene in normal hexane raw material, and the situation lower for benzene content is still applicable, adopts the method that energy consumption not only can be caused high, also can cause the benzene wasting of resources when benzene content is higher.When in raw material during benzene content height, after benzene is separated with normal hexane, an one-step refining of going forward side by side become purity to reach benzaldehyde product economy that relevant criterion requires is better.
The object of the invention is to develop a kind of production without benzene isohexane and the separation method without benzene normal hexane, produce high-purity benzaldehyde product simultaneously.
Summary of the invention
The object of the invention is to develop a kind of without benzene isohexane and high-purity, without the separation method of benzene normal hexane, produce high-purity benzaldehyde product simultaneously.The present invention proposes the separation method of a kind of normal hexane, isohexane and benzaldehyde product, particularly adopts the method that conventional distillation and extracting rectifying combine.
According to the present invention, from mixed feedstocks of hydrocarbons such as the raffinating oil of aromatic extraction unit, pyrolysis gasoline or straight-run spirit, first remove impurity more low-boiling than 2-methylpentane, then isolated not containing the mixing hexane of benzene by extraction rectifying method.Mixing hexane is separated into isohexane product and normal hexane product further.Remove the material after mixing hexane, after follow-up extraction rectifying method is separated, obtains benzaldehyde product.
Technical scheme of the present invention is as follows:
A kind of method being separated isohexane, normal hexane and benzaldehyde product; Comprise lights removal unit, hexane extraction rectification cell, hexane separating unit, the first solvent recovery unit, benzene extracting rectifying unit, the second solvent recovery unit and solvent regeneration unit; From mixed feedstocks of hydrocarbons such as the raffinating oil of aromatic extraction unit, pyrolysis gasoline or straight-run spirit, first remove impurity more low-boiling than 2-methylpentane, then isolate not containing the mixing hexane of benzene by extraction rectifying method; Mixing hexane is separated into isohexane product and normal hexane product further; Remove the material after mixing hexane, then obtain benzaldehyde product after extraction rectifying method is separated.
Realize the equipment of separation isohexane of the present invention, normal hexane and benzaldehyde product, be composed in series with flow direction of material by lightness-removing column 101, hexane extraction rectifying tower 105, hexane knockout tower 109, first solvent recovery tower 114, benzene extractive distillation column 119 and the second solvent recovery tower 124; Each tower top is provided with condenser, condenser is connected with return tank, and bottom is provided with reboiler; Hexane knockout tower 109 tower reactor connects normal hexane bleaching earth adsorption bed 303; Second solvent recovery tower 124 return tank of top of the tower 127 connects benzene bleaching earth adsorption bed 403; First solvent recovery tower 114 is connected solvent reclamation vaporizer 201 with the second solvent recovery tower 124 tower reactor.
Linking device of the present invention is adopted to carry out being separated the method for isohexane, normal hexane and benzaldehyde product, from the mixed feedstocks of hydrocarbons outside battery limit (BL) after feed preheater preheats, send into lightness-removing column 101, from lightness-removing column 101 removed overhead than after the low-boiling light constituent impurity of 2-methylpentane, send into hexane extraction rectifying tower 105 to be again separated, hexane extraction rectifying tower 105 overhead extraction is not containing the mixing hexane stream stock of benzene; The mixture flow stock of hexane extraction rectifying tower 105 tower reactor extraction solvent, benzene and a small amount of non-aromatics; Mixing hexane stream stock is sent into hexane knockout tower 109 and is separated, send into basin at hexane knockout tower 109 overhead extraction stream stock as isohexane product, obtain normal hexane product after normal hexane stream stock-traders' know-how bleaching earth adsorption bed 303 process of hexane knockout tower 109 tower reactor extraction and send into basin; Hexane extraction rectifying tower 105 still material is sent into the first solvent recovery tower 114 and is separated, solvent is recycled in the first solvent recovery tower 114 tower reactor, major part returns hexane and gets rectifying tower 105 Reusability after cooling, and rest part send solvent reclamation vaporizer 201 to carry out impurities removal; First solvent recovery tower 114 tower top obtains the mixture of benzene and non-aromatics impurity, and sends into benzene extractive distillation column 119 and be separated, and from benzene extracting rectifying 119 removed overhead non-aromatics impurity, and sends into basin as solvent oil product; Benzene extracting rectifying 119 tower reactor is the mixed flow stock of benzene and extraction agent, the second solvent recovery tower 124 is sent to be separated, solvent is recycled in the second solvent recovery tower 124 tower reactor, major part returns benzene extractive distillation column 119 Reusability after cooling, and rest part send solvent reclamation vaporizer 201 to carry out impurities removal; After benzene stream stock-traders' know-how bleaching earth adsorption bed 403 process of the second solvent recovery tower 124 overhead extraction, after cooling, obtain benzaldehyde product.
When not containing the heavy constituents such as toluene in mixed feedstocks of hydrocarbons, benzaldehyde product can be obtained without benzene refining unit.Be specially from the mixed feedstocks of hydrocarbons outside battery limit (BL) after feed preheater preheats, send into lightness-removing column, from removed overhead than after the low-boiling light constituent impurity of 2-methylpentane, then send into hexane extraction rectifying tower and be separated, overhead extraction is containing the mixing hexane stream stock of benzene.The mixture flow stock of tower reactor extraction solvent, benzene and a small amount of non-aromatics.Mixing hexane stream stock is sent into hexane knockout tower and is separated, and sends into basin, obtain normal hexane product and send into basin after the normal hexane stream stock-traders' know-how bleaching earth adsorption bed process of tower reactor extraction at hexane knockout tower overhead extraction stream stock as isohexane product.Hexane extraction rectifying kettle material is sent into the first solvent recovery tower and is separated, and is recycled solvent in tower reactor, and major part returns hexane and gets rectifying tower Reusability after cooling, and small part is sent solvent regeneration unit to carry out de-rearrangement and mixed; Tower top obtains the mixture of benzene and non-aromatics impurity.First solvent recuperation tower top stream stock is sent into benzene extractive distillation column and is separated, and from removed overhead non-aromatics impurity, and sends into basin as solvent oil product; Tower reactor is the mixed flow stock of benzene and extraction agent, send the second solvent recovery tower to be separated, is recycled solvent in tower reactor, and major part returns benzene extractive distillation column Reusability after cooling, and small part is sent solvent regeneration unit to carry out de-rearrangement and mixed; After the benzene stream stock-traders' know-how bleaching earth adsorption bed process of overhead extraction, then obtain benzaldehyde product send basin through cooling.
Described lightness-removing column working pressure is absolute pressure 130 ~ 300kPa; Hexane extraction rectifying tower, hexane knockout tower, benzene extractive distillation column and benzene refining tower working pressure are normal pressure; First solvent recovery tower and the second solvent recovery tower vacuum operating, the working pressure of this two tower is absolute pressure 20 ~ 60kPa.Regeneration vaporizer 201 is falling-film evaporator, and working pressure is absolute pressure 20 ~ 60kPa; Filler particles carclazyte in bleaching earth adsorption bed, the service temperature of bleaching earth adsorption bed 303 is 120 DEG C ~ 200 DEG C, working pressure 100 ~ 200kPa higher than the saturated vapor pressure of normal hexane under selected service temperature; The service temperature of bleaching earth adsorption bed 403 is 120 DEG C ~ 200 DEG C, working pressure 100 ~ 200kPa higher than the saturation pressure of benzene under selected service temperature.
The feature of described isohexane, normal hexane and benzaldehyde product separation method is that hexane extraction rectifying tower and benzene extractive distillation column tower adopt the method for extracting rectifying, and all the other each towers are conventional distillation method.
The extraction agent that described hexane extraction rectifying tower and benzene extractive distillation column use comprises glycols, N-Methyl pyrrolidone, tetramethylene sulfone, dimethyl sulfoxide (DMSO), N-formyl morpholine or is one or several the composite extractant in above-mentioned; Two extractive distillation columns can select identical extraction agent, also can select different extraction agents, and the add-on of extraction agent is 3 ~ 6 times of inlet amount.
The tower reactor extraction solvent cycle of the first solvent recovery tower and the second solvent recovery tower uses.
The feature of described bleaching earth adsorption bed is the packed bed of granular carclazyte, the alkene that it is characterized in that removing trace in product improves product bromine number and the micro-nitrogenous compound because of solvolysis generation, and product colourity can be improved, adoptable granular carclazyte comprises JH-01 and NC-01.
The feature of described solvent regeneration unit is to adopt falling film evaporator systems, by the first solvent recovery tower and the second solvent recovery tower share, vacuum operating, working pressure is absolute pressure 30kPa.
The feature of described benzene refining tower is to remove the heavy constituent impurity such as the toluene in benzene, and has certain function removing light constituent impurity; Be further characterized in that and whether can determine whether run containing heavy constituents such as toluene according in raw material.
The isohexane product 2-methylpentane adopting the technology of the present invention to produce and 3-methylpentane total mass mark are not less than 95%, and benzene content is less than 100ppm.
The normal hexane product indices adopting the technology of the present invention to produce, except being up to state standards GB16629-2008, outside China PetroChemical Corporation company standard Q/SH PRD0406-2011, and can reach the requirement that normal hexane massfraction is not less than 99%.
The benzaldehyde product adopting the technology of the present invention to produce is up to state standards GB3405-89.
Accompanying drawing explanation
The schematic flow sheet that the isohexane of Fig. 1 embodiment 1, normal hexane are separated with benzene.
The schematic flow sheet of Fig. 2 solvent regeneration system of the present invention.
Fig. 3 normal hexane bleaching earth adsorption of the present invention bed schematic flow sheet.
Fig. 4 benzene adsorption bed of the present invention schematic flow sheet.
The schematic flow sheet that the isohexane of Fig. 5 embodiment 2, normal hexane are separated with benzene.
Embodiment
Below in conjunction with accompanying drawing 1 ~ Fig. 4, the invention will be further described:
Equipment of the present invention is as follows: by lightness-removing column 101, hexane extraction rectifying tower 105, hexane knockout tower 109, first solvent recovery tower 114, benzene extractive distillation column 119, second solvent recovery tower 124, benzene refining tower 129 is composed in series; Each tower top is provided with condenser, condenser is connected with return tank, and bottom is provided with reboiler; Hexane knockout tower 109 tower reactor connects normal hexane bleaching earth adsorption bed 303; Second solvent recovery tower 124 return tank of top of the tower 127 connects benzene bleaching earth adsorption bed 403; First solvent recovery tower 114 is connected solvent reclamation vaporizer 201 with the second solvent recovery tower 124 tower reactor.
Embodiment 1
According to the separation method of a kind of isohexane of the present invention, normal hexane and benzene, from in the mixed feedstocks of hydrocarbons such as the raffinating oil of aromatic extraction unit, pyrolysis gasoline or straight-run spirit containing heavy constituents such as toluene time, sepn process is substantially identical with embodiment one, first remove impurity more low-boiling than 2-methylpentane, then isolated not containing the mixing hexane of benzene by extraction rectifying method.Mixing hexane is separated into isohexane product and normal hexane product further.Remove the material after mixing hexane, after follow-up extraction rectifying method is separated, obtains benzaldehyde product.
Technical process mainly comprises as lower unit: lights removal unit, hexane extraction rectification cell, hexane separating unit, the first solvent recovery unit, benzene extracting rectifying unit, the second solvent recovery unit and solvent regeneration unit.Below in conjunction with accompanying drawing, above-mentioned each unit is described.
From the total hydrocarbon feed outside battery limit (BL) after feed preheater preheats, from lightness-removing column 101 top charging, overhead vapours after condenser of light component removal column 102 condensation, lime set enter lightness-removing column return tank 103 part backflow, another part as light constituent product from return tank extraction.Lightness-removing column still arranges reboiler 104.This tower adopts pressurized operation to ensure that overhead vapours can be recycled cooling water condensation, and working pressure is that absolute pressure 160kPa(is applicable in 130kPa ~ 300kPa scope).The component of overhead extraction stream stock is mainly pentamethylene, the light hydrocarbons impurity that the boiling points such as 2,2-methylbutane are lower than 2-methylpentane.Lightness-removing column 101 tower reactor stream stock mainly consists of isohexane, normal hexane and benzene, sends into hexane extraction rectifying tower 105 and carries out later separation.
From the stream stock of lightness-removing column still from charging in the middle part of hexane extraction rectifying tower 105, extraction agent N-Methyl pyrrolidone (just exemplifies a kind of extraction agent here, the extraction agent that summary of the invention is mentioned is all applicable) from charging above feed plate, the add-on of extraction agent is 6 times (all applicable 3 times ~ 6 times scopes) of inlet amount.The effect of extraction agent increases hexane and methylcyclopentane, the relative volatility of hexane and benzene, thus the clear cutting of hexane and benzene is achieved.Under the effect of extraction agent, material in hexane extraction rectifying tower 105 through repeatedly gasifying, realize after multiple condensation being separated, overhead vapours is got after rectifying tower condenser 106 condensation through hexane and is obtained mixing hexane, enter hexane and get rectifier column reflux tank 107, part backflow, rest part send hexane knockout tower 109 to be separated further.Interchanger 108 is hexane extraction rectifying tower reactor reboiler, and the rich benzene extraction agent solution that tower reactor obtains is sent into the first solvent recovery tower 114 and carried out solvent recuperation.
After mixing hexane enters hexane knockout tower 109, after abundant vapour-liquid heat and mass, isohexane and normal hexane realize being separated, and overhead vapours, after hexane separation column condenser 110 condensation, enters hexane knockout tower return tank 111, part backflow; Rest part is as the extraction of isohexane product, and wherein 2-methylpentane and 3-methylpentane total concn are about 95%, and benzene content is lower than 100ppm.Interchanger 112 is the tower reactor reboiler of hexane knockout tower 109.For the normal hexane of tower reactor extraction, massfraction is higher than 99.0%, wherein benzene content is less than 100ppm, deliver to normal hexane first preheater 301 and normal hexane second preheater 302 be preheated to 170 DEG C after after (all applicable 120 DEG C ~ 200 DEG C scopes), process through bleaching earth adsorption bed 303 again, normal hexane product indices can be made can be up to state standards GB16629-2008, China PetroChemical Corporation company standard Q/SHPRD0406-2011, and normal hexane massfraction is not less than 99%.
Rich benzene extraction agent solution is in realization separation after vapour-liquid heat transfer, mass transfer in the first solvent recovery tower 114, tower top steams benzene and non-aromatics mixture, after the first solvent recovery tower condenser 115 and the first solvent recovery tower aftercooler 116 condensation, enter the first solvent recovery tower return tank 117.This tower adopts vacuum operating, and working pressure is that absolute pressure 30kPa(is applicable in 20kPa ~ 60kPa scope), the non-condensable gas of the first solvent recovery tower aftercooler 116 is extracted out by vacuum pump 133.Wherein the first solvent recovery tower condenser 115 adopts recirculated cooling water to do heat-eliminating medium, and temperature out controls within the scope of 37 ~ 47 DEG C; First solvent recovery tower aftercooler 116 adopts low-temperature cooling water to make heat-eliminating medium, and temperature out controls within the scope of 20 ~ 30 DEG C.Material part backflow in first solvent recovery tower return tank 117, all the other are sent into benzene extractive distillation column 119 and are separated further.First solvent recovery tower 114 tower reactor reclaims extraction agent N-methyl-pyrrolidon, and major part returns hexane extraction rectifying tower 107 and recycles after extraction agent water cooler 113 cools, and small part send 201 to carry out manipulation of regeneration.Interchanger 118 is the tower reactor reboiler of the first solvent recovery tower 114.
From benzene and the non-aromatics mixture of the first solvent recovery tower return tank 117, from the top charging of benzene extractive distillation column 119, extraction agent N-methyl-pyrrolidon (just exemplifies a kind of extraction agent here, the extraction agent that summary of the invention is mentioned is all applicable) add by above feed plate, the add-on of extraction agent is 6 times (all applicable 3 ~ 6 times of scopes) of benzene extractive distillation column 119 inlet amount.Under the effect of extraction agent, aromatic hydrocarbons and non-aromatics realize being separated, and the steam of non-aromatic hydro carbons is by after the condensation of benzene extractive distillation column condenser 120, and enter the backflow of benzene extractive distillation column return tank 121 part, rest part is as the extraction of solvent oil product.Interchanger 122 is the tower reactor reboiler of benzene extractive distillation column 119, and the mixture of benzene and extraction agent, from tower reactor extraction, is sent into the second molten recovery tower 124 and recycled.
Be separated at the second solvent recovery tower 124 with the mixture of extraction agent from the benzene of benzene extractive distillation column 119 tower reactor, overhead vapours is after the second solvent recovery tower condenser 125 and the second solvent recovery tower aftercooler 126 condensation, enter the second solvent recovery tower return tank 127, partial reflux, rest part extraction.The material of extraction part after (all applicable within the scope of 120 DEG C ~ 200 DEG C), delivered to bleaching earth adsorption bed 403 and is removed the impurity such as alkene after benzene first preheater 401 and benzene second preheater 402 are preheated to 170 DEG C.The material after alkene is removed from bleaching earth adsorption bed 403, through benzene first preheater 401 with from after the material-heat-exchanging of the second solvent recovery tower return tank 127 again, again through cooling further and can obtaining benzaldehyde product, product index can reach GB3405-89, and benzene massfraction is not less than 99.9%.
Second solvent recovery tower 124 tower adopts vacuum operating, and working pressure is that absolute pressure 30kPa(is applicable at 20kPa ~ 60kPa).Second solvent recovery tower condenser 125 adopts recirculated cooling water to do heat-eliminating medium, and temperature out controls within the scope of 37 ~ 47 DEG C; Second solvent recovery tower aftercooler 126 adopts low-temperature cooling water to make heat-eliminating medium, and temperature out controls within the scope of 20 ~ 30 DEG C.The non-condensable gas of the second solvent recovery tower aftercooler 126 is extracted out by vacuum pump 134.Second solvent recovery tower 124 tower reactor is Solvents N-methyl-pyrrolidone, and major part returns benzene extractive distillation column through extraction agent and recycles after water cooler 123 cools, and small portion send solvent reclamation vaporizer 201 to carry out manipulation of regeneration.
The extraction agent recycled, because coking can cause in solvent containing solid particle polluter, need regularly or continuously to remove, from the first solvent recovery tower 114 or the second solvent recovery tower 124 tower reactor, interval is drawn one feeding solvent reclamation vaporizer 201 and is carried out manipulation of regeneration, the solvent steamed enters regenerated solvent tank 205 by after regenerated solvent condenser 203 and regenerated solvent aftercooler 204 condensation, and returns solvent systems thus and reuse.Heavy constituent impurity is discharged by bottom regenerated solvent surge tank 202.Solvent regeneration system adopts vacuum operating, and working pressure is that absolute pressure 30kPa(is applicable at 20kPa ~ 60kPa), the non-condensable gas of regenerated solvent aftercooler 204 is extracted out by vacuum pump 206.
The isohexane product 2-methylpentane adopting the technology of the present invention to produce and 3-methylpentane total mass mark are not less than 95%, and benzene content is less than 100ppm.
The normal hexane product indices adopting the technology of the present invention to produce, except being up to state standards GB16629-2008, outside China PetroChemical Corporation company standard Q/SH PRD0406-2011, and can reach the requirement that normal hexane massfraction is not less than 99%.
The benzaldehyde product adopting the technology of the present invention to produce is up to state standards GB3405-89.
Embodiment 2
According to the separation method of a kind of isohexane of the present invention, normal hexane and benzene, from the raffinating oil of aromatic extraction unit, the mixed feedstocks of hydrocarbons such as pyrolysis gasoline or straight-run spirit, first remove impurity more low-boiling than 2-methylpentane, then isolated not containing the mixing hexane of benzene by extraction rectifying method.Mixing hexane is separated into isohexane product and normal hexane product further.Remove the material after mixing hexane, after follow-up extraction rectifying method is separated, obtains benzaldehyde product.The difference of the present embodiment and embodiment one is, benzene refining unit be adopted to obtain benzaldehyde product.
Technical process mainly comprises as lower unit: lights removal unit, hexane extraction rectification cell, hexane separating unit, the first solvent recovery unit, benzene extracting rectifying unit, the second solvent recovery unit, benzene refining unit and solvent regeneration unit.Below in conjunction with accompanying drawing, above-mentioned each unit is described.
From the total hydrocarbon feed outside battery limit (BL) after feed preheater preheats, from lightness-removing column 101 top charging, overhead vapours after condenser of light component removal column 102 condensation, lime set enter lightness-removing column return tank 103 part backflow, another part as light constituent product from return tank extraction.Lightness-removing column still arranges reboiler 104.This tower adopts pressurized operation to ensure that overhead vapours can be recycled cooling water condensation, and working pressure is that absolute pressure 130kPa(is applicable at 150kPa ~ 300kPa).The component of overhead extraction stream stock is mainly pentamethylene, the light hydrocarbons impurity that the boiling points such as 2,2-methylbutane are lower than 2-methylpentane.Lightness-removing column 101 tower reactor stream stock mainly consists of isohexane, normal hexane and benzene, sends into hexane extraction rectifying tower 105 and carries out later separation.
From the stream stock of lightness-removing column still from charging in the middle part of hexane extraction rectifying tower 105, extraction agent N-Methyl pyrrolidone (just exemplifies a kind of extraction agent here, the extraction agent that summary of the invention is mentioned is all applicable) from charging above feed plate, the add-on of extraction agent is 4 times (they can also be 3 times ~ 6 times) of inlet amount.The effect of extraction agent increases hexane and methylcyclopentane, the relative volatility of hexane and benzene, thus the clear cutting of hexane and benzene is achieved.Under the effect of extraction agent, material in hexane extraction rectifying tower 105 through repeatedly gasifying, realize after multiple condensation being separated, overhead vapours obtains mixing hexane after the condensation of hexane extraction rectifying tower condenser 106, enter hexane and get rectifier column reflux tank 107, part backflow, rest part extraction send hexane knockout tower 109 to be separated further.Interchanger 108 is hexane extraction rectifying tower reactor reboiler, and the rich benzene extraction agent solution that tower reactor obtains is sent into the first solvent recovery tower 114 and carried out solvent recuperation.
After mixing hexane enters hexane knockout tower 109, after abundant vapour-liquid heat and mass, isohexane and normal hexane realize being separated, and overhead vapours, after hexane separation column condenser 110 condensation, enters hexane knockout tower return tank 111, part backflow; Rest part is as the extraction of isohexane product, and wherein 2-methylpentane and 3-methylpentane total concn are about 95%, and benzene content is lower than 100ppm.Interchanger 112 is the tower reactor reboiler of hexane knockout tower 109.For the normal hexane of tower reactor extraction, massfraction is higher than 99.0%, wherein benzene content is less than 100ppm, deliver to normal hexane first preheater 301 and normal hexane second preheater 302 be preheated to 150 DEG C after (can also be 120 DEG C ~ 200 DEG C), process through bleaching earth adsorption bed 303 again, normal hexane product indices can be made can be up to state standards GB16629-2008, China PetroChemical Corporation company standard Q/SH PRD0406-2011, and normal hexane massfraction is not less than 99%.
Rich benzene extraction agent solution is in realization separation after vapour-liquid heat transfer, mass transfer in the first solvent recovery tower 114, tower top steams benzene and non-aromatics mixture, after the first solvent recovery tower condenser 115 and the first solvent recovery tower aftercooler 116 condensation, enter the first solvent recovery tower return tank 117.This tower adopts vacuum operating, and working pressure is that absolute pressure 30kPa(is applicable in 20kPa ~ 60kPa scope), the non-condensable gas of the first solvent recovery tower aftercooler 116 is extracted out by vacuum pump 133.Wherein the first solvent recovery tower condenser 115 adopts recirculated cooling water to do heat-eliminating medium, and temperature out controls within the scope of 37 ~ 47 DEG C; First solvent recovery tower aftercooler 116 adopts low-temperature cooling water to make heat-eliminating medium, and temperature out controls within the scope of 20 ~ 30 DEG C.Material part backflow in first solvent recovery tower return tank 117, all the other are sent into benzene extractive distillation column 119 and are separated further.First solvent recovery tower 114 tower reactor reclaims extraction agent N-methyl-pyrrolidon, and major part returns hexane extraction rectifying tower 107 and recycles after extraction agent water cooler 113 cools, and small part send 201 to carry out manipulation of regeneration.Interchanger 118 is the tower reactor reboiler of the first solvent recovery tower 114.
From benzene and the non-aromatics mixture of the first solvent recovery tower return tank 117, from the top charging of benzene extractive distillation column 119, extraction agent N-methyl-pyrrolidon (just exemplifies a kind of extraction agent here, the extraction agent that summary of the invention is mentioned is all applicable) add by above feed plate, the add-on of extraction agent is 5 times (all applicable 3 ~ 6 times of scopes) of benzene extractive distillation column 119 inlet amount.Under the effect of extraction agent, aromatic hydrocarbons and non-aromatics realize being separated, and the steam of non-aromatic hydro carbons is by after the condensation of benzene extractive distillation column condenser 120, and enter the backflow of benzene extractive distillation column return tank 121 part, rest part is as the extraction of solvent oil product.Interchanger 122 is the tower reactor reboiler of benzene extractive distillation column 119, and the mixture of benzene and extraction agent, from tower reactor extraction, is sent into the second molten recovery tower 124 and recycled.
Be separated at the second solvent recovery tower 124 with the mixture of extraction agent from the benzene of benzene extractive distillation column 119 tower reactor, overhead vapours is after the second solvent recovery tower condenser 125 and the second solvent recovery tower aftercooler 126 condensation, enter the second solvent recovery tower return tank 127, partial reflux, rest part extraction.The material (can also be 120 DEG C ~ 200 DEG C) after benzene first preheater 401 and benzene second preheater 402 are preheated to 150 DEG C of extraction part, delivers to bleaching earth adsorption bed 403 and removes the impurity such as alkene, then delivers to benzene refining tower 129 and refine further.
Second solvent recovery tower 124 tower adopts vacuum operating, and working pressure is absolute pressure 30kPa(can also be all applicable in 20kPa ~ 60kPa scope).Second solvent recovery tower condenser 125 adopts recirculated cooling water to do heat-eliminating medium, and temperature out controls within the scope of 37 ~ 47 DEG C; Second solvent recovery tower aftercooler 126 adopts low-temperature cooling water to make heat-eliminating medium, and temperature out controls within the scope of 20 ~ 30 DEG C.The non-condensable gas of the second solvent recovery tower aftercooler 126 is extracted out by vacuum pump 134.Second solvent recovery tower 124 tower reactor is Solvents N-methyl-pyrrolidone, and major part returns benzene extractive distillation column through extraction agent and recycles after water cooler 123 cools, and small portion send solvent reclamation vaporizer 201 to carry out manipulation of regeneration.
From the material of bleaching earth adsorption bed 403, after benzene first preheater 401 with the material-heat-exchanging from the second solvent recovery tower return tank 127, send into benzene refining tower 129 and be separated.Benzene refining tower 129 overhead vapours, after the condensation of benzene refining tower condenser 130, enters benzene refining tower return tank 131, major part backflow, interval extraction light constituent impurity.Benzaldehyde product is by the top side take-off of benzene refining tower 129, and benzaldehyde product index can reach GB3405-89, and benzene massfraction is not less than 99.9%.
The extraction agent recycled, because coking can cause in solvent containing solid particle polluter, need regularly or continuously to remove, from the first solvent recovery tower 114 or the second solvent recovery tower 124 tower reactor, interval is drawn one feeding solvent reclamation vaporizer 201 and is carried out manipulation of regeneration, the solvent steamed enters regenerated solvent tank 205 by after regenerated solvent condenser 203 and regenerated solvent aftercooler 204 condensation, and returns solvent systems thus and reuse.Heavy constituent impurity is discharged by bottom regenerated solvent surge tank 202.Solvent regeneration system adopts vacuum operating, and working pressure is that absolute pressure 30kPa(is applicable in 20kPa ~ 60kPa scope), the non-condensable gas of regenerated solvent aftercooler 204 is extracted out by vacuum pump 206.
The isohexane product 2-methylpentane adopting the technology of the present invention to produce and 3-methylpentane total mass mark are not less than 95%, and benzene content is less than 100ppm.
The normal hexane product indices adopting the technology of the present invention to produce, except being up to state standards GB16629-2008, outside China PetroChemical Corporation company standard Q/SH PRD0406-2011, and can reach the requirement that normal hexane massfraction is not less than 99%.
The benzaldehyde product adopting the technology of the present invention to produce is up to state standards GB3405-89.
Claims (5)
1. be separated a method for isohexane, normal hexane and benzaldehyde product, it is characterized in that comprising lights removal unit, hexane extraction rectification cell, hexane separating unit, the first solvent recovery unit, benzene extracting rectifying unit, the second solvent recovery unit, solvent regeneration unit and bleaching earth adsorption bed; From the raffinating oil of aromatic extraction unit, pyrolysis gasoline or straight-run spirit mixed feedstocks of hydrocarbons, first remove impurity more low-boiling than 2-methylpentane, then isolate not containing the mixing hexane of benzene by extraction rectifying method; Mixing hexane is separated into isohexane product and normal hexane product further; Remove the material after mixing hexane, then obtain benzaldehyde product after extraction rectifying method is separated; Described hexane extraction rectification cell and the adoptable extraction agent of benzene extracting rectifying unit comprise glycols, N-Methyl pyrrolidone, tetramethylene sulfone, dimethyl sulfoxide (DMSO), N-formyl morpholine or are one or several the composite extractant in above-mentioned; The extraction agent that benzene extracting rectification tower adopts and n-hexane extraction rectifying tower identical or different.
2. realize the equipment of claim 1 method, it is characterized in that being composed in series with flow direction of material by lightness-removing column (101), hexane extraction rectifying tower (105), hexane knockout tower (109), the first solvent recovery tower (114), benzene extractive distillation column (119) and the second solvent recovery tower (124); Each tower top is provided with condenser, condenser is connected with return tank, and bottom is provided with reboiler; Hexane knockout tower (109) tower reactor connects normal hexane bleaching earth adsorption bed (303); Second solvent recovery tower (124) return tank of top of the tower (127) connects benzene bleaching earth adsorption bed (403); First solvent recovery tower (114) is connected solvent reclamation vaporizer (201) with the second solvent recovery tower (124) tower reactor.
3. adopt equipment as claimed in claim 2 to carry out being separated the method for isohexane, normal hexane and benzaldehyde product, it is characterized in that from the mixed feedstocks of hydrocarbons outside battery limit (BL) after feed preheater preheats, send into lightness-removing column (101), from lightness-removing column (101) removed overhead than after the low-boiling light constituent impurity of 2-methylpentane, send into hexane extraction rectifying tower (105) to be again separated, hexane extraction rectifying tower (105) overhead extraction is not containing the mixing hexane stream stock of benzene; The mixture flow stock of hexane extraction rectifying tower (105) tower reactor extraction solvent, benzene and a small amount of non-aromatics; Mixing hexane stream stock is sent into hexane knockout tower (109) and is separated, send into basin at hexane knockout tower (109) overhead extraction stream stock as isohexane product, obtain normal hexane product after normal hexane stream stock-traders' know-how bleaching earth adsorption bed (303) process of hexane knockout tower (109) tower reactor extraction and send into basin; Hexane extraction rectifying tower (105) still material is sent into the first solvent recovery tower (114) and is separated, solvent is recycled in the first solvent recovery tower (114) tower reactor, major part returns hexane and gets rectifying tower (105) Reusability after cooling, and rest part send solvent reclamation vaporizer (201) to carry out impurities removal; First solvent recovery tower (114) tower top obtains the mixture of benzene and non-aromatics impurity, and send into benzene extractive distillation column (119) and be separated, from benzene extractive distillation column (119) removed overhead non-aromatics impurity, and send into basin as solvent oil product; Benzene extractive distillation column (119) tower reactor is the mixed flow stock of benzene and extraction agent, the second solvent recovery tower (124) is sent to be separated, solvent is recycled in the second solvent recovery tower (124) tower reactor, major part returns benzene extractive distillation column (119) Reusability after cooling, and rest part send solvent reclamation vaporizer (201) to carry out impurities removal; After benzene stream stock-traders' know-how bleaching earth adsorption bed (403) process of the second solvent recovery tower (124) overhead extraction, after cooling, obtain benzaldehyde product.
4. method as claimed in claim 3, is characterized in that lightness-removing column working pressure is absolute pressure 130 ~ 300kPa; Hexane extraction rectifying tower, hexane knockout tower, benzene extractive distillation column and benzene refining tower working pressure are normal pressure; First solvent recovery tower and the second solvent recovery tower vacuum operating, the working pressure of this two tower is absolute pressure 20 ~ 60kPa; Regeneration vaporizer (201) is falling-film evaporator, and working pressure is absolute pressure 20 ~ 60kPa; Filler particles carclazyte in bleaching earth adsorption bed, the service temperature of bleaching earth adsorption bed (303) is 120 DEG C ~ 200 DEG C, working pressure 100 ~ 200kPa higher than the saturated vapor pressure of normal hexane under selected service temperature; The service temperature of bleaching earth adsorption bed (403) is 120 DEG C ~ 200 DEG C, working pressure 100 ~ 200kPa higher than the saturation pressure of benzene under selected service temperature.
5. method as claimed in claim 1, it is characterized in that tower extraction agent adds by above feed plate, add-on is 3 ~ 6 times of hexane tower feedstock quality.
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| CN103242121B (en) * | 2013-05-02 | 2015-07-29 | 天津大学 | The working method of normal hexane and benzene extracting rectifying |
| RU2568114C2 (en) * | 2014-03-13 | 2015-11-10 | Общество с ограниченной ответственностью "Производственное объединение "Киришинефтеоргсинтез" | Method of separating benzene from mixtures with non-aromatic hydrocarbons |
| CN105130733B (en) * | 2015-09-29 | 2017-09-26 | 东营市俊源石油技术开发有限公司 | A kind of monomer alkane refrigerant preparation facilities and method |
| CN105950213A (en) * | 2016-06-30 | 2016-09-21 | 东营市俊源石油技术开发有限公司 | Environment-friendly solvent and partial monomer alkane production device and use method thereof |
| KR101851871B1 (en) * | 2016-10-31 | 2018-04-25 | 한화토탈 주식회사 | A process for various purity of n-hexane and iso-hexane using dearomatized oil as feedstock |
| CN108238838B (en) * | 2016-12-26 | 2021-02-05 | 中国石油化工股份有限公司 | Method for producing benzene with high yield by using C6 alkane |
| CN109053354A (en) * | 2018-10-11 | 2018-12-21 | 成都科特瑞兴科技有限公司 | A kind of cyclohexyl benzene system for separating and purifying and the technique using system purification cyclohexyl benzene |
| CN110819442B (en) * | 2019-11-07 | 2021-08-24 | 岳阳金瀚高新技术股份有限公司 | Grease leaching solvent and preparation method thereof |
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| CN1238313C (en) * | 2004-04-27 | 2006-01-25 | 广州赫尔普化工有限公司 | Method for preparing isohexane solvent |
| CN101172928B (en) * | 2007-11-06 | 2010-06-02 | 哈尔滨工程大学 | Method for salt extraction separation of benzol-cyclohexane normal heptane |
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