CN104030880B - The method of direct crystallisation by cooling separating paraxylene - Google Patents
The method of direct crystallisation by cooling separating paraxylene Download PDFInfo
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- CN104030880B CN104030880B CN201310345374.2A CN201310345374A CN104030880B CN 104030880 B CN104030880 B CN 104030880B CN 201310345374 A CN201310345374 A CN 201310345374A CN 104030880 B CN104030880 B CN 104030880B
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Abstract
A kind of method that the present invention relates to direct crystallisation by cooling separating paraxylene, mainly solves the problem that in prior art, flow process is complicated, number of devices is many and investment cost is high.The present invention a kind of method by adopting direct crystallisation by cooling separating paraxylene, in the crystallizer with agitator, inertia cryogenic liquid is passed in the raw material including Mixed XYLENE and carry out direct heat transfer, make inertia cryogenic liquid vaporizer and cool down the raw material that includes Mixed XYLENE, crystallization high-purity paraxylene crystals in the described raw material including Mixed XYLENE, the technical scheme discharging crystallizer in slurry form solves the problems referred to above preferably, can be used in the industrial installation comprising crystallization process separation of produced xylol.
Description
Technical field
A kind of method that the present invention relates to direct crystallisation by cooling separating paraxylene.
Background technology
C8 aromatic hydrocarbons has o-Dimethylbenzene, meta-xylene, xylol and four kinds of isomerss of ethylbenzene.Wherein the demand of xylol is the most extensive, is mostly used in production polyester raw material-p-phthalic acid (PTA).
The technological process of industrial separation xylol mainly has adsorption method of separation and perfectly crystallization process two kinds at present.When para-xylene concentration is relatively low in raw material Mixed XYLENE, adopt adsorption method of separation to have comparative advantages, but when para-xylene concentration is higher in raw material Mixed XYLENE, adopt perfectly crystallization process advantageously.In actual industrial production, it is also possible to combination uses both separation methods, plays respective advantage.
Perfectly crystallization process is based on xylol fusing point (13.3 DEG C) and wants high feature (o-Dimethylbenzene fusing point is-25.2 DEG C, and meta-xylene fusing point is-47.9 DEG C) to be easily separated compared with other component fusing point.Paraxylene crystals will be precipitated out at first during the cooling of raw material Mixed XYLENE.
CN200810043977.6 relates to a kind of method of xylol Crystallization Separation, sends in crystallizer containing the mixed xylenes that para-xylene concentration is 60～95% and carries out crystallisation by cooling, crystallizes out the slurry containing paraxylene crystals；Purification by filtration unit sent into by slurry, separates and obtains mother solution, scrub raffinate and pure xylol.Crystallizer in current Crystallization Separation xylol process program mostly is indirect heat exchange type crystallizer, mainly has double-pipe chiller and vertical crystallizer two class.This two classes crystallizer all uses cryogenic coolant, cools down raw material Mixed XYLENE by indirect heat exchange mode so that it is precipitating out paraxylene crystals, the internal structure of crystallizer is all complex.
On the one hand, being limited to the process condition requirement of indirect heat exchange type crystallizer, cryogenic coolant and the raw material Mixed XYLENE temperature difference can not be too big；On the other hand, being limited to equipment and materials and device manufacturing process, the heat exchange area of separate unit indirect heat exchange type crystallizer can not infinitely increase, and therefore the production capacity of separate unit indirect heat exchange type crystallizer is limited.When unit scale expands, owing to separate unit indirect heat exchange type production capacity of crystallizer for co-production of ammonium is limited, technological process typically requires some indirect heat exchange type crystallizers in parallel and can meet the requirement that production scale expands.
Summary of the invention
The technical problem to be solved is the problem that in prior art, flow process is complicated, number of devices is many and investment cost is high, it is provided that a kind of method of new direct crystallisation by cooling separating paraxylene.The method is used in the industrial installation comprising crystallization process separation of produced xylol, has the advantage that flow process is simple, number of devices is few and investment cost is low.
For solving the problems referred to above, the technical solution used in the present invention is as follows: a kind of method of direct crystallisation by cooling separating paraxylene, in the crystallizer with agitator, inertia cryogenic liquid is passed in the raw material including Mixed XYLENE and carry out direct heat transfer, make inertia cryogenic liquid vaporizer and cool down the raw material that includes Mixed XYLENE, in the described raw material including Mixed XYLENE, crystallization high-purity paraxylene crystals, discharges crystallizer in slurry form.
In technique scheme, it is preferable that described Mixed XYLENE Main Ingredients and Appearance is C8 aromatic hydrocarbons, it is also possible to contain the composition such as propyl benzene, C10 aromatic hydrocarbons on a small quantity.
In technique scheme, it is preferable that described crystallizer operation temperature is-47.9 DEG C～13.3 DEG C, it is more preferable to ground, for-15 DEG C～10 DEG C.
In technique scheme, it is preferable that described inertia cryogenic liquid is at least one in liquid nitrogen, liquid CO 2, liquid argon or liquid helium, it is more preferable to ground, at least one in liquid nitrogen or liquid CO 2.
In technique scheme, it is preferable that in described crystallizer, the crystal weight content of dimethylbenzene slurry is 10～90%, it is more preferable to ground, weight content is 20～60%.
In technique scheme, it is preferable that in described crystallizer, crystallization degree control program is at least one in the crystalline content of control crystallizer operation temperature, control dimethylbenzene slurry；Described method is continuous operation or intermittently operated.
In technique scheme, it is preferable that described from crystallizer expellant gas can Recovery Purifying recycling.
In the present invention, in a crystallizer with agitator, having the Mixed XYLENE raw material of certain liquid level, this burst of Mixed XYLENE raw material initial stage can be entirely liquid, it is also possible to is the slurry containing partial crystals.Mixed XYLENE material liquid is passed directly into inertia cryogenic liquid, by the direct heat transfer with raw material Mixed XYLENE, inertia cryogenic liquid vaporizer and the cooling of raw material Mixed XYLENE, crystallization high-purity paraxylene crystals in the raw material Mixed XYLENE of cooling.By controlling operation temperature or other technological parameter (in crystallizer the crystalline content of dimethylbenzene slurry) of crystallizer, it can be ensured that the crystal Main Ingredients and Appearance of precipitation is xylol.
Agitator in crystallizer plays a part to help inertia cryogenic liquid and slurry in slurry heat exchange and Homogeneous phase mixing crystallizer on the one hand；Also the crystal of larger particles in crystallizer is played fragmentation on the other hand.In direct crystallisation by cooling process, crystal quickly forms, in crystal, easily wrap up crystalline mother solution, the fragmentation of agitator can be broken apart out by the crystalline mother solution wrapped up in crystal, that reduces crystallization further contains mother solution entrainment, improving the content of xylol in crystal, meanwhile, crystal in small, broken bits also allows for the slurry conveying in follow-up solid-liquid separation process.
The operation pressure of crystallizer is also little on the impact of crystallization process, and crystallizer is typically in direct draught operation.
Optionally, discharge from crystallizer after inertia cryogenic liquid vaporizer, again liquefy after recovered process.So can save the consumption of inertia cryogenic liquid.Reclaim in cyclic process at gas, need to frequently discharge a small amount of gas and supplement fresh inertia cryogenic liquid, it is prevented that the accumulation of impurity in inertia cryogenic liquid.
If under some condition of technology and economy, when after discharging from crystallizer after inertia cryogenic liquid vaporizer, directly recycling is uneconomical, then this portion gas can also go to other device or equipment recycling.
Adopt technological process disclosed by the invention, indirect heat exchange type crystallizer required in tradition crystallization technological process can be cancelled, production scale is easily amplified in technological process disclosed in this invention, required crystallizer quantity relatively adopts quantity during indirect heat exchange type crystallizer to be greatly reduced, and the also more traditional indirect heat exchange crystallizer of the cost of manufacture of crystallizer is low, the equipment investment expense of device will be greatly reduced, and achieve good technique effect.
Accompanying drawing explanation
Fig. 1 is the process flow diagram of the method for the invention.
In Fig. 1,1 is crystallizer；2 is inertia cryogenic liquid feeding line；3 is crystallizer gas outlet pipe line；4 is feedstock pipeline；5 is the Mixed XYLENE stock discharge pipeline containing paraxylene crystals.
In Fig. 1, raw material passes into the crystallizer 1 with agitator by feedstock pipeline 4, inertia cryogenic liquid is also passed into crystallizer 1 by inertia cryogenic liquid feeding line 2, in crystallizer 1, the heat absorption vaporization of inertia cryogenic liquid, the gas after heat absorption vaporization discharges crystallizer 1 by crystallizer gas outlet pipe line 3.Meanwhile, in crystallizer 1, the Mixed XYLENE cooling in raw material precipitates out paraxylene crystals, and the Mixed XYLENE slurry containing paraxylene crystals discharges crystallizer 1 from pipeline 5.
The present invention is further elaborated by the examples below, but is not limited only to the present embodiment.
Detailed description of the invention
Following embodiment is only for the present invention is described further, but these embodiments are not limitation of the scope of the invention, because those skilled in the art will recognize that without departing from the premise in the spirit of the present invention, it is possible to the present invention makes multiple amendment.
[embodiment 1]
Flow process shown in Fig. 1, the raw material that xylol content is 60wt% flows in crystallizer, passes into liquid nitrogen, controls crystallizer operation temperature near-15 DEG C, and the crystalline content in slurry is about 40wt%.Temperature and the influx of crystal solid content adjustment liquid nitrogen is operated according to crystallizer.Dimethylbenzene slurry containing paraxylene crystals is sent to solid-liquid separating equipment to carry out solid-liquid separation or is sent to crystal curing equipment and carries out the further ripening of crystal.By the output of the nitrogen after control heat absorption vaporization, maintain the operation pressure of crystallizer in 5 bars (gauge pressure) left and right.
The nitrogen of vaporization uses the absorption/desorption tank purified treatment of two handover operations, is sent to liquid nitrogen producing equipment post liquefaction again and is sent to crystallizer after purified process.
[embodiment 2]
Flow process shown in Fig. 1, the raw material that xylol content is 80wt% flows in crystallizer, passes into liquid nitrogen, controls crystallizer operation temperature near-10 DEG C, and the crystalline content in slurry is about 30wt%.Temperature and the influx of crystal solid content adjustment liquid nitrogen is operated according to crystallizer.Dimethylbenzene slurry containing paraxylene crystals is sent to solid-liquid separating equipment to carry out solid-liquid separation or is sent to crystal curing equipment and carries out the further ripening of crystal.By the output of the nitrogen after control heat absorption vaporization, maintain the operation pressure of crystallizer in 2 bars (gauge pressure) left and right.
[embodiment 3]
Flow process shown in Fig. 1, the raw material that xylol content is 80wt% flows in crystallizer, passes into liquid nitrogen, controls crystallizer operation temperature near-13.3 DEG C, and the crystalline content in slurry is about 20wt%.Temperature and the influx of crystal solid content adjustment liquid nitrogen is operated according to crystallizer.Dimethylbenzene slurry containing paraxylene crystals is sent to solid-liquid separating equipment to carry out solid-liquid separation or is sent to crystal curing equipment and carries out the further ripening of crystal.By the output of the nitrogen after control heat absorption vaporization, maintain the operation pressure of crystallizer in 3 bars (gauge pressure) left and right.
[embodiment 4]
Flow process shown in Fig. 1, the raw material that xylol content is 30wt% flows in crystallizer, passes into liquid nitrogen, controls crystallizer operation temperature near-47.9 DEG C, and the crystalline content in slurry is about 50wt%.Temperature and the influx of crystal solid content adjustment liquid nitrogen is operated according to crystallizer.Dimethylbenzene slurry containing paraxylene crystals is sent to solid-liquid separating equipment to carry out solid-liquid separation or is sent to crystal curing equipment and carries out the further ripening of crystal.By the output of the nitrogen after control heat absorption vaporization, maintain the operation pressure of crystallizer in 4 bars (gauge pressure) left and right.
[embodiment 5]
Flow process shown in Fig. 1, the raw material that xylol content is 50wt% flows in crystallizer, passes into liquid nitrogen, controls crystallizer operation temperature near-25.2 DEG C, and the crystalline content in slurry is about 60wt%.Operate temperature according to crystallizer and regulate the influx of liquid nitrogen.Dimethylbenzene slurry containing paraxylene crystals is sent to solid-liquid separating equipment to carry out solid-liquid separation or is sent to crystal curing equipment and carries out the further ripening of crystal.By the output of the nitrogen after control heat absorption vaporization, maintain the operation pressure of crystallizer in 3.5 bars (gauge pressure) left and right.
[embodiment 6]
Flow process shown in Fig. 1, the raw material that xylol content is 60wt% flows in crystallizer, passes into liquid CO 2, controls crystallizer operation temperature near-15 DEG C, and the crystalline content in slurry is about 40wt%.Temperature and the influx of crystal solid content adjustment liquid CO 2 is operated according to crystallizer.Dimethylbenzene slurry containing paraxylene crystals is sent to solid-liquid separating equipment to carry out solid-liquid separation or is sent to crystal curing equipment and carries out the further ripening of crystal.By the output of the carbon dioxide after control heat absorption vaporization, maintain the operation pressure of crystallizer in 5 bars (gauge pressure) left and right.
The carbon dioxide of vaporization uses the absorption/desorption tank purified treatment of two handover operations, is sent to liquid CO 2 producing equipment post liquefaction again and is sent to crystallizer after purified process.
[embodiment 7]
Flow process shown in Fig. 1, the raw material that xylol content is 80wt% flows in crystallizer, passes into liquid CO 2, controls crystallizer operation temperature near-10 DEG C, and the crystalline content in slurry is about 10wt%.Temperature and the influx of crystal solid content adjustment liquid CO 2 is operated according to crystallizer.Dimethylbenzene slurry containing paraxylene crystals is sent to solid-liquid separating equipment to carry out solid-liquid separation or is sent to crystal curing equipment and carries out the further ripening of crystal.By the output of the carbon dioxide after control heat absorption vaporization, maintain the operation pressure of crystallizer in 2 bars (gauge pressure) left and right.
Claims (7)
1. the method for a direct crystallisation by cooling separating paraxylene, in the crystallizer with agitator, inertia cryogenic liquid is passed in the raw material including Mixed XYLENE and carry out direct heat transfer, make inertia cryogenic liquid vaporizer and cool down the raw material that includes Mixed XYLENE, from the described raw material including Mixed XYLENE, crystallization high-purity paraxylene crystals, discharges crystallizer in slurry form；Described inertia cryogenic liquid is at least one in liquid nitrogen, liquid CO 2, liquid argon or liquid helium；Described crystallizer operation temperature is-47.9 DEG C～13.3 DEG C, and in described crystallizer, the crystal weight content of dimethylbenzene slurry is 10～90%.
2. the method for a kind of direct crystallisation by cooling separating paraxylene according to claim 1, it is characterised in that described Mixed XYLENE is mainly composed of C8 aromatic hydrocarbons, and containing propyl benzene, C10 aromatic fractions.
3. the method for a kind of direct crystallisation by cooling separating paraxylene according to claim 1, it is characterised in that described crystallizer operation temperature is-15 DEG C～10 DEG C.
4. the method for a kind of direct crystallisation by cooling separating paraxylene according to claim 1, it is characterised in that in described crystallizer, the crystal weight content of dimethylbenzene slurry is 20～60%.
5. the method for a kind of direct crystallisation by cooling separating paraxylene according to claim 1, it is characterised in that in described crystallizer crystallization degree control program be control crystallizer operation temperature, control the crystalline content of dimethylbenzene slurry at least one；Described method is continuous operation or intermittently operated.
6. the method for a kind of direct crystallisation by cooling separating paraxylene according to claim 1, it is characterised in that described inertia cryogenic liquid is at least one in liquid nitrogen or liquid CO 2.
7. the method for a kind of direct crystallisation by cooling separating paraxylene according to claim 1, it is characterised in that can Recovery Purifying recycling from crystallizer expellant gas.
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| CN104557436A (en) * | 2015-02-05 | 2015-04-29 | 中石化上海工程有限公司 | Method for directly cooling, crystallizing and separating p-xylene by virtue of one-step process |
| CN108794295B (en) * | 2018-05-30 | 2021-01-08 | 重庆三峡学院 | Method for crystallizing and separating p-xylene |
| CN110180209A (en) * | 2019-06-19 | 2019-08-30 | 陕西宏元化工技术有限公司 | A kind of cooling crystallization method directly to exchange heat |
| CN113813638B (en) * | 2021-11-02 | 2022-10-11 | 江西思远再生资源有限公司 | Method for separating water and calcium chloride by eutectic freezing crystallization |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN88100630A (en) * | 1987-02-06 | 1988-11-09 | 克鲁普科普斯有限公司 | The preparation method of the p-Xylol of purity at least 99.5% |
| CN101151080A (en) * | 2005-03-30 | 2008-03-26 | 月岛机械株式会社 | Method and apparatus for crystallization of organic compound through adiabatic cooling |
| CN102060651A (en) * | 2010-11-05 | 2011-05-18 | 华东理工大学 | Method and device for combining and separating mixed xylene slurry |
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| CN101735001B (en) * | 2008-11-21 | 2013-04-03 | 中国石油化工股份有限公司 | Method for separating p-xylene crystal |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN88100630A (en) * | 1987-02-06 | 1988-11-09 | 克鲁普科普斯有限公司 | The preparation method of the p-Xylol of purity at least 99.5% |
| CN101151080A (en) * | 2005-03-30 | 2008-03-26 | 月岛机械株式会社 | Method and apparatus for crystallization of organic compound through adiabatic cooling |
| CN102060651A (en) * | 2010-11-05 | 2011-05-18 | 华东理工大学 | Method and device for combining and separating mixed xylene slurry |
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