CN103288585A - Method for separating styrene from C8 fraction - Google Patents
Method for separating styrene from C8 fraction Download PDFInfo
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- CN103288585A CN103288585A CN2012100431658A CN201210043165A CN103288585A CN 103288585 A CN103288585 A CN 103288585A CN 2012100431658 A CN2012100431658 A CN 2012100431658A CN 201210043165 A CN201210043165 A CN 201210043165A CN 103288585 A CN103288585 A CN 103288585A
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- extractive distillation
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Abstract
The invention discloses a method for separating styrene from a C8 fraction. The method comprises the following steps of: carrying out extractive distillation on the C8 fraction in an extractive distillation tower so as to separate styrene, and completely or partially substituting raffinate oil by using a water phase to be used as liquid phase reflux in a solvent recycling section in the extractive distillation tower, wherein the water phase is a reflux tank water supply on the top of the extractive distillation tower, or free water separated in a liquid separating tower, or compensated or added desalted water. By utilizing the method disclosed by the invention, the concentration of o-xylene in the extractive distillation tower is reduced through the reflux water phase, the solvent ratio and the reflux ratio are decreased, the styrene lost is reduced, and the operation flexibility is improved.
Description
Technical field
The present invention relates to chemical field, say further, relate to a kind of from carbon eight cuts the method for separating phenylethylene.
Background technology
Along with the construction of megaton ethene, reclaim vinylbenzene technology in carbon eight cuts from pyrolysis gasoline, have a good application prospect and economic benefit.Because the boiling point of vinylbenzene and other aromatic hydrocarbons is more or less the same in pyrolysis gasoline carbon eight cuts, particularly the boiling point of vinylbenzene and o-Xylol differs less than 1 ℃, and both relative volatilities can't adopt conventional rectification to separate near 1.0 when solvent-free.Usually adopt the method for extracting rectifying, change o-Xylol and cinnamic relative volatility by solvent, from pyrolysis gasoline, isolate polymerization-grade vinylbenzene.
The flow process that conventional process has been continued to use conventional extractive distillation column as shown in Figure 1, solvent 5-15 piece plate under the cat head enters extractive distillation column, the C8 raw material enters from the tower middle part, stripped vapor adds from tower reactor or reboiler, overhead vapours is after condensation, part backflows of raffinating oil, water stripping is discharge after the water bag is collected.
The main purpose of extractive distillation column trim the top of column is the existence that keeps solvent recuperation section liquid phase, prevents that solvent from losing from cat head.In common process, cat head has been raffinated oil in (oil phase) enrichment a large amount of o-Xylol, enter extractive distillation column as backflow, increased the content of o-Xylol in the extractive distillation column internal recycle (shown in square frame among the figure), thereby increased o-Xylol and cinnamic separating difficulty.
Summary of the invention
Be to solve problems of the prior art, the invention provides a kind of from carbon eight cuts the method for separating phenylethylene.Reduce the concentration of o-Xylol in the extractive distillation column mutually by recirculation water, reduce solvent ratio, reduce reflux ratio, reduce the vinylbenzene loss, increase turndown ratio.
The purpose of this invention is to provide a kind of from carbon eight cuts the method for separating phenylethylene.
Comprise: carbon eight cuts are isolated vinylbenzene behind extracting rectifying in extractive distillation column,
Wherein, adopt all or part of replacement of water to raffinate oil as the liquid-phase reflux of described extractive distillation column internal solvent recovery zone.
Described water is the return tank water bag of extracting rectifying column overhead or divides the free-water that separates in the flow container or replenish the de-salted water that adds.
The present invention is achieved through the following technical solutions: by return tank water bag or the free-water of branch flow container separation or the de-salted water of additional interpolation etc., part replaces in (or all replacing) traditional extraction rectification process as raffinating oil of refluxing, as the liquid phase of solvent recuperation section, to reduce the particularly content of o-Xylol of raffinating oil in the extractive distillation column.
The operational condition of extractive distillation column can adopt common operational condition in the prior art.Preferably in the negative pressure state operation, pressure maintains 10-15KPa.A to extractive distillation column among the present invention.
Specifically can comprise following steps:
(1) extractive distillation column is operated in negative pressure state, and pressure maintains 10-15KPa.A;
(2) extraction solvent enters extractive distillation column from tower top 5-15 piece plate;
(3) the C8 cut enters from appropriate location, tower middle part;
(4) add stripped vapor in tower reactor or the reboiler;
(5) the water bag on the return tank is used in the cat head extraction, or gun barrel or decanting vessel etc., separates and raffinates oil and water;
(6) oil-containing water or fresh deionized water partly or entirely replace the backflow of raffinating oil;
(7) cat head obtains the product of raffinating oil;
(8) obtain containing cinnamic rich solvent at the bottom of the tower.
Effect of the present invention is: reduce the concentration of o-Xylol in the extractive distillation column mutually by recirculation water, this method has the following advantages:
1. can reduce the content of raffinating oil in the extractive distillation column, particularly reduce the content of o-Xylol.Certain pyrolysis gasoline contains vinylbenzene 35wt% in forming, o-Xylol 15%, reflux ratio 0.55, vinylbenzene in the tower: o-Xylol=1.25: 1; If adopt whole water phase to reflux, vinylbenzene in the tower: o-Xylol=2.3: 1.
2. traditional oil phase reflow method is compared, and whole water phase or part aqueous-phase reflux can reduce solvent ratio;
3. traditional oil phase reflow method is compared, and whole water phase or part aqueous-phase reflux can reduce the vinylbenzene loss;
4. can reduce reflux ratio, traditional oil phase reflow method reflux ratio is about 0.9-1.2, and adopting whole water phase to reflux can be control of reflux ratio about 0.2.
5. can increase turndown ratio, traditional oil phase refluxes, when quantity of reflux surpasses 1.5 times of left and right sides of normal value, the excess of non-aromatic component refluxes and can destroy full tower balance, and the content of o-Xylol increases in the bottom product, adopts whole water phase to reflux, increase quantity of reflux 2-3 doubly, can not influence the bottom product quality.
Description of drawings
Extracting, rectifying and separating phenylethylene schema in Fig. 1 prior art
Fig. 2 extracting, rectifying and separating phenylethylene schema of the present invention
Description of reference numerals:
The 1-extractive distillation column; The 2-reboiler; The 3-condenser; The 4-return tank; The 5-extraction distillation solvent; 6-carbon eight raw materials; The 7-stripped vapor; The 8-rich solvent; 9-raffinates oil; The 10-liquid-phase reflux; The 11-water
Embodiment
Below in conjunction with embodiment, further specify the present invention.
Embodiment:
As shown in Figure 2, the pyrolysis gasoline from cracker comes through the cut cutting, obtains the C8 cut, and its composition sees Table 1, and temperature is 60 ℃.Carbon eight cuts enter in the tower from the extractive distillation column middle part, extraction distillation solvent enters from tower top, stripped vapor enters in tower reactor or reboiler, carbon eight cuts and extraction distillation solvent carry out extracting rectifying in tower, the extractive distillation column overhead vapours enters return tank after condensation, isolated raffinating oil as the product extraction, isolated water returns the extracting rectifying top of tower as liquid-phase reflux.The rich solvent of extractive distillation column tower reactor rich in styrene, a part enters reboiler, return in the tower after the part vaporization, gas phase in the tower is provided, another part extraction is in follow-up solvent recovery tower, continue separating phenylethylene and solvent, the working pressure that the flow of each logistics and composition see Table 2. extractive distillation columns is 15kPa.A
The composition (weight percentage) of table 1 carbon eight cuts
| C8 alkane | C8 alkene | Toluene | Ethylbenzene | P-Xylol | M-xylene | O-Xylol | Vinylbenzene |
| 2.5 | 2.5 | 1 | 18 | 5 | 25 | 12 | 34 |
Each logistics flux of table 2 aqueous-phase reflux and composition
| The |
6 | 7 | 8 | 9 | 10 |
| Logistics is described | Raw material C8 cut | Stripped vapor at the bottom of the tower | Rich solvent | Raffinate oil | Aqueous-phase reflux |
| Phase | Liquid | Steam | Liquid | Liquid | Liquid |
| Temperature ℃ | 75 | 110 | 137 | 45 | 45 |
| Mass rate kg/hr | 10000 | 1712 | 62876 | 6650 | 1566 |
| The quality percentage composition | |||||
| C8 alkane | 2.50 | 0.00 | 0.00 | 3.76 | 0.00 |
| The non-aromatic alkene of C8 | 2.50 | 0.00 | 0.00 | 3.76 | 0.00 |
| Toluene | 1.00 | 0.00 | 0.00 | 1.50 | 0.00 |
| Ethylbenzene | 18.00 | 0.00 | 0.00 | 27.06 | 0.00 |
| P-Xylol | 5.00 | 0.00 | 0.00 | 7.52 | 0.00 |
| M-xylene | 25.00 | 0.00 | 0.00 | 37.59 | 0.01 |
| O-Xylol | 12.00 | 0.00 | 0.00 | 18.00 | 0.00 |
| Vinylbenzene | 34.00 | 0.00 | 5.34 | 0.75 | 0.00 |
| Solvent | 0.00 | 0.00 | 94.56 | 0.00 | 0.00 |
| Water | 0.00 | 100.00 | 0.10 | 0.06 | 99.99 |
Comparative Examples:
As shown in Figure 1, raffinate oil as liquid-phase reflux all the other same embodiment except adopting.The flow composition of each logistics sees Table 3.
Table 3 oil phase reflux each logistics flux and composition
| The |
6 | 7 | 8 | 9 | 10 |
| Logistics is described | Raw material C8 cut | Stripped vapor at the bottom of the tower | Rich solvent | Raffinate oil | Oil phase refluxes |
| Phase | Liquid | Steam | Liquid | Liquid | Liquid |
| Temperature ℃ | 75 | 110 | 137 | 45 | 45 |
| Mass rate kg/hr | 10000 | 1688 | 62857 | 6678 | 7564 |
| The quality percentage composition | |||||
| C8 alkane | 2.5 | 0 | 0 | 3.74 | 3.74 |
| C8 alkene | 2.5 | 0 | 0 | 3.74 | 3.74 |
| Toluene | 1 | 0 | 0 | 1.50 | 1.50 |
| Ethylbenzene | 18 | 0 | 0 | 27.00 | 27.00 |
| P-Xylol | 5 | 0 | 0 | 7.51 | 7.51 |
| M-xylene | 25 | 0 | 0 | 37.45 | 37.45 |
| O-Xylol | 12 | 0 | 0 | 17.97 | 17.97 |
| Vinylbenzene | 34 | 0 | 5.31 | 1.04 | 1.04 |
| Solvent | 0 | 0 | 94.59 | 0.00 | 0.00 |
| Water | 0 | 100 | 0.1 | 0.06 | 0.06 |
From the data of table 2 and table 3 as seen, under the identical situation of C8 charging, solvent ratio, the quantity of reflux that oil phase refluxes is 7564kg/h, and the oil phase reflux ratio is 0.9, and the quantity of reflux of aqueous-phase reflux is 1566kg/h, and the aqueous-phase reflux ratio is 0.16, refluxes than oil phase and reduces greatly; Cinnamic rate of loss is reduced to 1.46% of aqueous-phase reflux by 2.04% of the oil phase backflow in raffinating oil, and per hour about vinylbenzene that can reduce loses 20kg.
Claims (4)
1. the method for a separating phenylethylene from carbon eight cuts, comprising: carbon eight cuts are isolated vinylbenzene behind extracting rectifying in extractive distillation column, it is characterized in that:
Adopt all or part of replacement of water to raffinate oil as the liquid-phase reflux of described extractive distillation column internal solvent recovery zone.
As claimed in claim 1 from carbon eight cuts the method for separating phenylethylene, it is characterized in that:
Described water is the return tank water bag of extracting rectifying column overhead or divides the free-water that separates in the flow container or replenish the de-salted water that adds.
As claimed in claim 2 from carbon eight cuts the method for separating phenylethylene, it is characterized in that may further comprise the steps:
(1) extracting rectifying is carried out with the extraction distillation solvent that top from extractive distillation column enters in the carbon eight cuts middle part that enters extractive distillation column, and stripped vapor is added by tower reactor;
(2) overhead vapours is isolated after condensation and is raffinated oil and water, and aqueous portion or whole the replacement raffinate oil as the cat head liquid-phase reflux;
(3) obtain raffinating oil as the product output, the extracting rectifying column overhead obtains containing cinnamic rich solvent.
As claimed in claim 3 from carbon eight cuts the method for separating phenylethylene, it is characterized in that:
The working pressure of described extractive distillation column is 10-15kPa.A.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210043165.8A CN103288585B (en) | 2012-02-23 | 2012-02-23 | A kind of method of separating phenylethylene from carbon eight cut |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210043165.8A CN103288585B (en) | 2012-02-23 | 2012-02-23 | A kind of method of separating phenylethylene from carbon eight cut |
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| CN103288585A true CN103288585A (en) | 2013-09-11 |
| CN103288585B CN103288585B (en) | 2015-09-09 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3944483A (en) * | 1972-12-20 | 1976-03-16 | Krupp-Koppers Gmbh | Distillative recovery of aromatics with water addition in azeotropic proportions |
| US4039602A (en) * | 1975-05-06 | 1977-08-02 | Universal Oil Products Company | Ethylbenzene Dehydrogenation process |
| CN101468938A (en) * | 2007-12-28 | 2009-07-01 | 中国石油化工股份有限公司 | Double solvent for extracting, distilling and separating styrene in hydrocarbons mixture |
-
2012
- 2012-02-23 CN CN201210043165.8A patent/CN103288585B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3944483A (en) * | 1972-12-20 | 1976-03-16 | Krupp-Koppers Gmbh | Distillative recovery of aromatics with water addition in azeotropic proportions |
| US4039602A (en) * | 1975-05-06 | 1977-08-02 | Universal Oil Products Company | Ethylbenzene Dehydrogenation process |
| CN101468938A (en) * | 2007-12-28 | 2009-07-01 | 中国石油化工股份有限公司 | Double solvent for extracting, distilling and separating styrene in hydrocarbons mixture |
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| CN103288585B (en) | 2015-09-09 |
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Address after: 100728 No. 22 North Main Street, Chaoyang District, Beijing, Chaoyangmen Patentee after: China Petrochemical Group Co., Ltd Patentee after: Sinopec Engineering Construction Co., Ltd Address before: 100728 No. 22 North Main Street, Chaoyang District, Beijing, Chaoyangmen Patentee before: China Petrochemical Corp Patentee before: Sinopec Engineering Construction Co., Ltd |
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