CN1260340A - Method for separating arene by using extraction and rectification - Google Patents
Method for separating arene by using extraction and rectification Download PDFInfo
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- CN1260340A CN1260340A CN 99108038 CN99108038A CN1260340A CN 1260340 A CN1260340 A CN 1260340A CN 99108038 CN99108038 CN 99108038 CN 99108038 A CN99108038 A CN 99108038A CN 1260340 A CN1260340 A CN 1260340A
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Abstract
The method for separating aromatic hydrocarbon from hydrocarbons mixture by using extraction and rectification tower includes the following steps: feeding hydrocarbons mixture into extraction rectification tower from the middle portion of said tower, feeding selective solvent into the extraction rectification tower from upper portion of raw material inlet, after extraction and rectification discharging non-aromatic hydrocarbon from top of extraction rectification tower, discharging rich solvent containing aromatic hydrocarbon from bottom of extraction rectification tower and feeding it into solvent recvery tower to separate aromatic hydrocarbon from selective solvent, dividing lean solvent discharged from bottom of recovery tower into two portions, returning one portion of lean solvent after heat-exchanged into the extraction rectification tower, and making another portion of lean solvent undergo the process of flash evaporation treatment to obtain purified solvent, after heat-exchanged, erturning it into extraction rectification tower from upper portion of lean solvent inlet, and returning the flash-discharged aromatic hydrocarbon and selective solvent mixture into solvent recovery tower. It not only can separate aromatic hydrocarbon from hydrocarbons mixture, but also can separate benzene.
Description
The present invention utilizes extracting rectifying from the hydrocarbon mixture that contains aromatic hydrocarbons, particularly the method for aromatics separation in the hydrocarbon mixture that aromaticity content is high.
Extraction rectification technique since have flow process and simple to operate, facility investment is low, low power consumption and other advantages, is suitable for the hydrocarbon mixture aromatics separation from high aromaticity content, as separate benzene,toluene,xylene from reformed oil or cracking hydrogenated gasoline.
It is the technology that is called the Distapex method of solvent that existing extraction rectification technique mainly contains with the N-Methyl pyrrolidone, and also having with morpholine class such as N-formyl morpholine or tetramethylene sulfone is the extraction rectification technique of solvent.All these technologies recycle after all the selective solvent of extracting rectifying will being reclaimed, and that is to say, will carry out solvent recuperation in extracting rectifying.General for the high hydrocarbon raw material of aromaticity content, before extracting rectifying, usually raw material is divided in advance fraction that is rich in benzene and the fraction that is rich in toluene, and then these two kinds of fractions are introduced extractive distillation column from different position, the production method of a kind of purified petroleum benzin and pure toluene is disclosed as CN1169413A, the raw material that this method will contain aromatic hydrocarbons is fractionated into rich benzene fraction in advance and is the richest in the benzene fraction, to be the richest in the benzene fraction then and send into distillation tower earlier and carry out fore-distillation, send into the extracting rectifying section again after removing high boiling component.This method is applicable to aromatics separation product from coal tar crude benzol and/or the pyrolysis gasoline that obtains of processing crude oil, and obviously, the employed equipment of this method is more, complex operation.
Owing to be subjected to the restriction of solvent thermal decomposition temperature, existing extractive distillation technology or guarantee that to sacrifice aromatic recovery rate solvent recuperation operates under than the demulcent condition at one, perhaps make solvent recuperation at one than exacting terms, as the quality of the lean solvent after improving the vacuum tightness of recovery tower and the temperature at the bottom of the recovery tower and guaranteeing to reclaim, consequently increased the possibility of solvolysis.In addition, extraction rectification technique is suitable for reclaiming aromatic hydrocarbons most from the high raw material of aromaticity content, because the non-aromatics content in the raw material is very low, correspondingly the epimere gas phase load at the extractive distillation column opening for feed is very low, the epimere operation efficiency of tower is also very low, and therefore, CN1175568A proposes that the lean solvent that obtains at the bottom of the solvent recovery tower is divided into two strands and sends into extractive distillation column, wherein the opening for feed of second shunting is positioned at the cat head part on the first shunting top, and second shunting only accounts for 0.5～10% of solvent total amount.Adding second shunting is in order to increase the efficient of extractive distillation column epimere.This method makes the efficient of extracting rectifying can not get improving at all owing to the aromaticity content that can not reduce in the circulating solvent.
The purpose of this invention is to provide a kind of extraction and distillation technology that utilizes, under demulcent solvent recuperation condition comparatively from the hydrocarbon mixture that contains aromatic hydrocarbons the method for aromatics separation expeditiously.
The inventive method comprises: hydrocarbon mixture enters extractive distillation column from the middle part, selective solvent enters extractive distillation column from the top of material inlet, through extracting rectifying, non-aromatics is discharged from the extracting rectifying cat head, the rich solvent that contains aromatic hydrocarbons is discharged at the bottom of the extractive distillation column and is entered solvent recovery tower aromatic hydrocarbons is separated with selective solvent, the lean solvent that discharge the recovery tower bottom carries out flash distillation, the purifying solvent that flash distillation obtains is back to the top of extractive distillation column, and the aromatic hydrocarbons that flashes out and the mixture of selective solvent turn back to solvent recovery tower.
The solvent that carries out flash distillation in the aforesaid method can be whole lean solvents, also can be the part lean solvent.If whole lean solvents are carried out returning extractive distillation column after flash distillation further purifies solvent, the efficient of extractive distillation column can be improved, but the energy consumption of device also can increase thereupon, think the energy consumption of further reduction extracting rectifying system, improve the comprehensive effectiveness of whole extracting rectifying aromatics separation system, method is the lean solvent separated into two parts that the recovery tower bottom is discharged preferably, part lean solvent returns the top of extractive distillation column, another part lean solvent enters the solvent flashing jar and carries out flash distillation, further to remove the aromatic hydrocarbons in the lean solvent, the aromatic hydrocarbons that flashes out and the mixture of selective solvent turn back to solvent recovery tower, and the purifying solvent that flash distillation obtains is back to extractive distillation column on the top of lean solvent inlet.
The effect of flash distillation is that the lean solvent of will discharge at the bottom of the recovery tower further separates with aromatic hydrocarbons, obtain more purified selective solvent with recovery, this more pure solvent is the top that purifying solvent is back to extraction distillation column, can improve the efficient of extractive distillation column effectively.The lean solvent that is flashed is many more, and the purifying solvent that enters extractive distillation column is also just many more, and the effect of extracting rectifying is just good more, but energy consumption also increases thereupon.In actually operating, more efficiently method is only the part of the lean solvent of discharge at the bottom of the recovery tower to be sent into flash tank to carry out flash distillation, the purifying solvent that obtains through flash distillation enters extractive distillation column from the top of lean solvent inlet again, suitably the flash distillation amount of control recovery solvent can reduce the energy consumption of device, can improve the efficient of extractive distillation column again.So carry out 15～80 heavy % that the lean solvent of flash distillation preferably accounts for the lean solvent total amount, preferred flash distillation amount is 30～60 heavy % of lean solvent total amount.
Aromaticity content can drop to 0.05～0.5 heavy % in the purifying solvent that flash distillation obtains, and the aromaticity content of the lean solvent of discharging at the bottom of the general recovery tower is 1.0～2.5 heavy %.And in the prior art, aromaticity content in the lean solvent is further reduced, will increase the number of theoretical plate of solvent recovery tower, its volume is increased, also will improve the vacuum tightness and the column bottom temperature of recovery tower simultaneously, this will make the cost of device and process cost increase greatly.
It is low that described flash distillation working pressure should reclaim tower top pressure, and suitable working pressure is 0.015～0.045MPa, and the temperature of flash distillation is 160～190 ℃.Because the existence of flash distillation, the pressure of recovery tower can be controlled in 0.04～0.07MPa, and column bottom temperature is 170～190 ℃, relaxes than the recovering condition of the extraction distillation solvent of prior art.
Described selective solvent is selected from the sulfone class that N-replaces morpholine or contains 5～7 carbon atoms, and preferred solvent is N-formyl morpholine, tetramethylene sulfone, and most preferred solvent is the N-formyl morpholine.
Method of the present invention is applicable to from containing the hydrocarbon mixture of aromatic hydrocarbons, particularly aromaticity content greater than 60 heavy %, is aromatics separation in the hydrocarbon mixture of 60～98 heavy % as aromaticity content.
Fig. 1 carries out flash distillation round-robin schematic flow sheet in the inventive method with partial solvent.
Fig. 1 Raw enters extractive distillation column 2 from pipeline 1, selective solvent enters the top of extractive distillation column 2 by pipeline 8, and through extracting rectifying, the non-aromatics steam of cat head is after pipeline 3 enters condenser 4 condensations, a part is discharged by pipeline 5, and remainder passes back into tower 2 tops through pipeline 6. Extractive distillation column 2 bottoms contain the rich solvent of aromatic hydrocarbons and discharge through pipeline 7, sent into again the top of solvent recovery tower 11 by pipeline 10, this tower 11 under reduced pressure operates, overhead stream is discharged by pipeline 12, after condenser 13 condensations, enter return tank 14, liquid part in the return tank 14 passes back into the top of recovery tower 11 by pipeline 15, and remainder is discharged from pipeline 16 as aromatic hydrocarbon product, and the pressure of recovery tower vacuumizes control by pipeline 17 places. A lean solvent part of discharging at the bottom of the recovery tower through heat exchanger 18 and 19 heat exchange after, directly be back to the top of extractive distillation column 2 by pipeline 8, another part lean solvent is sent into flash tank 21 by pipeline 20 and is carried out flash distillation, after purifying solvent process heat exchanger 26 heat exchange by the discharge of flash tank 21 bottoms, process pipeline 9 enters extractive distillation column 2 from the top of lean solvent charging aperture, the steam at flash tank 14 tops enters condenser 23 condensations through pipeline 22, condensate enters tank 24, enter pipeline 10 through pipeline 25 again and deliver to recovery tower 11, with further recovery aromatic hydrocarbons, the pressure of flash tank 21 vacuumizes control by pipeline 27 places.
The lean solvent that the method that the inventive method adopts flash distillation is discharged at the bottom of with recovery tower further purifies, particularly after being flashed purification, a part of lean solvent enters separately again extraction from the top of lean solvent import when heating up in a steamer tower, both can improve the efficient of extracting rectifying, can make again the operating condition of recovery tower obtain relaxing, therefore the energy consumption of device also descends thereupon. Under same operating condition, to compare with the extracting rectifying of not solubilizer flash distillation, in the situation that non-aromatics content is identical in the control aromatic hydrocarbon product, aromatic recovery rate improves.
Further specify the present invention below by example, but the present invention is not limited to this.
Example 1
The benzene fraction that this example obtains through cutting with the cracking hydrogenated gasoline is a raw material, according to the separation process Separation of Benzene of Fig. 1.Main operational condition during separation and the results are shown in Table 1.Wherein the content of benzene is 80 heavy % in the raw material.
Example 2
Get the raw material in the example 1, flow process Separation of Benzene with reference to Fig. 1, the lean solvent that different is discharges at the bottom of the recovery tower all enters flash tank and further purifies, discharge at the bottom of the flash tank, be back to the top of extractive distillation column again through the solvent that purifies, that is to say that the solvent that enters extractive distillation column has only an inlet.Main operational condition during separation and the results are shown in Table 1.
Comparative Examples
Get the raw material in the example 1, according to the method for CN1175568A, the lean solvent of discharging at the bottom of the recovery tower is divided into two shuntings, second shunting enters extractive distillation column from the top, and its inlet is on the top of first solvent shunting.Isolating operational condition and the results are shown in Table 1.
By table 1 data as can be known, with method of the present invention lean solvent is recycled through returning extractive distillation column again after the flash distillation, because the aromatic hydrocarbons amount that the purifying solvent after the flash distillation contains than lean solvent still less, therefore after purifying solvent is back to extractive distillation column, can improve the rate of recovery of benzene, do not carry out the method for solvent flashing with CN1175568A and compare, the benzene yield increases, and the benzene content in the non-aromatics greatly reduces.
Table 1
| Operational condition and separating resulting | Example 1 | Example 2 | Comparative Examples | |
| Extractive distillation column | Number of theoretical plate | ????25 | ????25 | ????25 |
| Lean solvent is to the weight ratio of raw material | ????3.0 | ????- | ????4.3 | |
| Purifying solvent is to the weight ratio of raw material | ????1.5 | ????4.5 | ????0.2 * | |
| Lean solvent is gone into column plate number | ????7 | ????- | ????7 | |
| Purifying solvent is gone into column plate number | ????2 | ????2 | ????2 | |
| Lean solvent benzene content, heavy % | ????1.2 | ????- | ????1.2 | |
| Purifying solvent benzene content, heavy % | ????0.25 | ????0.25 | ????1.2 * | |
| Recovery tower | Tower top pressure, MPa | ????0.046 | ????0.046 | ????0.046 |
| Tower bottom pressure, MPa | ????0.065 | ????0.065 | ????0.065 | |
| Column bottom temperature, ℃ | ????188 | ????188 | ????188 | |
| Flash tank | Pressure, MPa | ????0.025 | ????0.025 | ????- |
| Temperature, ℃ | ????172 | ????172 | ????- | |
| Product | Non-aromatics content in the benzene, ppm | ????370 | ????370 | ????380 |
| The benzene yield, heavy % | ????99.7 | ????99.8 | ????98.9 | |
| Benzene content in the non-aromatics, heavy % | ????1.23 | ????0.79 | ????4.07 | |
*The labelled notation place is the data of described second solvent shunting of CN1175568A.
Claims (10)
1, a kind of method of utilizing extracting rectifying aromatics separation from hydrocarbon mixture, comprise that hydrocarbon mixture enters extractive distillation column from the middle part, selective solvent enters extractive distillation column from the top of material inlet, through extracting rectifying, non-aromatics is discharged from the extracting rectifying cat head, the rich solvent that contains aromatic hydrocarbons is discharged at the bottom of the extractive distillation column and is entered solvent recovery tower aromatic hydrocarbons is separated with selective solvent, it is characterized in that the lean solvent that discharge the recovery tower bottom carries out flash distillation, the purifying solvent that flash distillation obtains is back to the top of extractive distillation column, and the aromatic hydrocarbons that flashes out and the mixture of selective solvent turn back to solvent recovery tower.
2, in accordance with the method for claim 1, it is characterized in that the lean solvent part that discharges recovery tower bottom returns the top of extractive distillation column, another part lean solvent carries out flash distillation to be handled, the purifying solvent that flash distillation obtains is back to extractive distillation column on the top of lean solvent inlet, and the aromatic hydrocarbons that flashes out and the mixture of selective solvent turn back to solvent recovery tower.
3, in accordance with the method for claim 2, the lean solvent that it is characterized in that carrying out flash distillation accounts for 15～80 heavy % of lean solvent total amount.
4, according to claim 2 or 3 described methods, the lean solvent that it is characterized in that carrying out flash distillation accounts for 30～60 heavy % of lean solvent total amount.
5, according to claim 1 or 2 described methods, the working pressure that it is characterized in that flash distillation is 0.015～0.045MPa, and temperature is 160～190 ℃.
6,, it is characterized in that selective solvent is N-replacement morpholine or the sulfone class that contains 5～7 carbon atoms according to claim 1 or 2 described methods.
7, in accordance with the method for claim 6, it is characterized in that selective solvent is the N-formyl morpholine.
8, in accordance with the method for claim 6, it is characterized in that selective solvent is a tetramethylene sulfone.
9,, it is characterized in that the content of aromatic hydrocarbons in the purifying solvent that flash distillation obtains is 0.05～0.5 heavy % according to claim 1 or 2 described methods.
10, according to claim 1 or 2 described methods, the content that it is characterized in that aromatic hydrocarbons in the described hydrocarbon mixture is 60～98 heavy %.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN99108038A CN1083819C (en) | 1999-06-11 | 1999-06-11 | Method for separating arene by using extraction and rectification |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN99108038A CN1083819C (en) | 1999-06-11 | 1999-06-11 | Method for separating arene by using extraction and rectification |
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| CN1260340A true CN1260340A (en) | 2000-07-19 |
| CN1083819C CN1083819C (en) | 2002-05-01 |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100378048C (en) * | 2005-08-31 | 2008-04-02 | 中国石油化工股份有限公司 | Method of extracting, rectifying and separating aromatic hydrocarbons and extracting and rectifying apparatus |
| CN100460373C (en) * | 2006-02-28 | 2009-02-11 | 中国石油化工股份有限公司 | Method for extracting rectifying and separating benzene |
| CN101875593A (en) * | 2010-07-12 | 2010-11-03 | 天津凯赛特科技有限公司 | Process for refining para-xylene and extracting styrene from para-xylene |
| CN101941877A (en) * | 2009-06-02 | 2011-01-12 | 环球油品公司 | Be used for removing the method and apparatus of pollutent from the selective aromatics solvent |
| CN103980954A (en) * | 2014-05-28 | 2014-08-13 | 西南化工研究设计院有限公司 | Removal method for benzenoid hydrocarbon in coke oven gas |
| CN104058916A (en) * | 2014-07-01 | 2014-09-24 | 西南化工研究设计院有限公司 | Morpholine-class mixed solvent for isolating arene through extraction and rectification and method for isolating arene |
| CN106831299A (en) * | 2017-04-01 | 2017-06-13 | 天津奥展兴达化工技术有限公司 | A kind of aromatic hydrocarbons extraction system of efficient energy-saving |
| CN112920162A (en) * | 2021-01-29 | 2021-06-08 | 临涣焦化股份有限公司 | Solvent regenerating unit |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4238716A1 (en) * | 1992-11-17 | 1994-05-19 | Krupp Koppers Gmbh | Process for the separation of hydrocarbon mixtures by extractive distillation |
| US5399244A (en) * | 1993-12-06 | 1995-03-21 | Glitsch, Inc. | Process to recover benzene from mixed hydrocarbons by extractive distillation |
| DE19630771C1 (en) * | 1996-07-31 | 1998-01-29 | Krupp Uhde Gmbh | Process for the production of pure hydrocarbons from an aromatic and non-aromatic hydrocarbon mixture |
-
1999
- 1999-06-11 CN CN99108038A patent/CN1083819C/en not_active Expired - Lifetime
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100378048C (en) * | 2005-08-31 | 2008-04-02 | 中国石油化工股份有限公司 | Method of extracting, rectifying and separating aromatic hydrocarbons and extracting and rectifying apparatus |
| CN100460373C (en) * | 2006-02-28 | 2009-02-11 | 中国石油化工股份有限公司 | Method for extracting rectifying and separating benzene |
| CN101941877A (en) * | 2009-06-02 | 2011-01-12 | 环球油品公司 | Be used for removing the method and apparatus of pollutent from the selective aromatics solvent |
| CN101941877B (en) * | 2009-06-02 | 2015-11-25 | 环球油品公司 | For removing the method and apparatus of pollutent from selective aromatics solvent |
| CN101875593A (en) * | 2010-07-12 | 2010-11-03 | 天津凯赛特科技有限公司 | Process for refining para-xylene and extracting styrene from para-xylene |
| CN103980954A (en) * | 2014-05-28 | 2014-08-13 | 西南化工研究设计院有限公司 | Removal method for benzenoid hydrocarbon in coke oven gas |
| CN103980954B (en) * | 2014-05-28 | 2016-02-03 | 西南化工研究设计院有限公司 | The removal methods of benzene hydrocarbon in a kind of coke-oven gas |
| CN104058916A (en) * | 2014-07-01 | 2014-09-24 | 西南化工研究设计院有限公司 | Morpholine-class mixed solvent for isolating arene through extraction and rectification and method for isolating arene |
| CN106831299A (en) * | 2017-04-01 | 2017-06-13 | 天津奥展兴达化工技术有限公司 | A kind of aromatic hydrocarbons extraction system of efficient energy-saving |
| CN112920162A (en) * | 2021-01-29 | 2021-06-08 | 临涣焦化股份有限公司 | Solvent regenerating unit |
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| Publication number | Publication date |
|---|---|
| CN1083819C (en) | 2002-05-01 |
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