CN104030880A - Method for directly cooling, crystallizing and separating paraxylene - Google Patents
Method for directly cooling, crystallizing and separating paraxylene Download PDFInfo
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- CN104030880A CN104030880A CN201310345374.2A CN201310345374A CN104030880A CN 104030880 A CN104030880 A CN 104030880A CN 201310345374 A CN201310345374 A CN 201310345374A CN 104030880 A CN104030880 A CN 104030880A
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Abstract
The invention relates to a method for directly cooling, crystallizing and separating paraxylene, which solves the problems of complex flow, mass equipment quantity and high investment cost in prior art. The method comprises the following steps: in a crystallization pot with a stirrer, inertia low temperature liquid is introduced in a raw material mixed with xylene and then directly subjected to heat exchange, vaporizing the inertia low temperature liquid and cooling the raw material mixed with xylene, crystallizing and precipitating the high purity paraxylene crystal from the raw material mixed with xylene, and discharging out of the crystallization pot by taking a slurry form; the technical scheme better solves the above problem. The method can be used for industrial production apparatus by using a crystallization process for separating and producing paraxylene.
Description
Technical field
The present invention relates to a kind of method of direct crystallisation by cooling separating paraxylene.
Background technology
C8 aromatic hydrocarbons has o-Xylol, m-xylene, p-Xylol and four kinds of isomerss of ethylbenzene.Wherein the demand of p-Xylol is the most extensive, most of for the production of polyester raw material-pure terephthalic acid (PTA).
At present the technical process of industrial separation p-Xylol mainly contains two kinds of adsorption method of separation and perfectly crystallization processes.In the time that p-Xylol concentration is lower in raw material Mixed XYLENE, adopts adsorption method of separation to have comparative advantages, but in the time that p-Xylol concentration is higher in raw material Mixed XYLENE, adopt perfectly crystallization process more to have superiority.In actual industrial production, also can be used in combination this two kinds of separation methods, performance advantage separately.
Perfectly crystallization process is to want high feature (o-Xylol fusing point is-25.2 DEG C, and m-xylene fusing point is for-47.9 DEG C) to separate according to p-Xylol fusing point (13.3 DEG C) compared with other component fusing point.When the cooling of raw material Mixed XYLENE, will separate out at first p-Xylol crystal.
CN200810043977.6 relates to a kind of method of p-Xylol Crystallization Separation, and the xylol that is 60～95% containing p-Xylol concentration is sent in crystallizer and carried out crystallisation by cooling, and crystallization goes out the slurry containing p-Xylol crystal; Slurry is sent into filtration purification unit, separates and obtains mother liquor, scrub raffinate and pure p-Xylol.Crystallizer in Crystallization Separation p-Xylol process program mostly is indirect heat exchange type crystallizer at present, mainly contains double-pipe crystallizer and vertical crystallizer two classes.This two classes crystallizer all uses cryogenic coolant, by the cooling raw material Mixed XYLENE of indirect heat exchange mode, makes it separate out p-Xylol crystal, and the internal structure of crystallizer is all comparatively complicated.
On the one hand, be limited to the process conditions requirement of indirect heat exchange type crystallizer, cryogenic coolant and the raw material Mixed XYLENE temperature difference can not be too large; On the other hand, be limited to equipment and materials and device manufacturing process, the heat interchanging area of separate unit indirect heat exchange type crystallizer can not infinitely increase, and therefore the throughput of separate unit indirect heat exchange type crystallizer is limited.In the time that unit scale expands, because separate unit indirect heat exchange type crystallizer throughput is limited, in technical process, conventionally need some indirect heat exchange type crystallizers in parallel can meet the requirement that industrial scale expands.
Summary of the invention
Technical problem to be solved by this invention is the many and high problem of investment cost of flow process complexity in prior art, number of devices, and a kind of method of new direct crystallisation by cooling separating paraxylene is provided.The industrial installation of the method for comprising crystallization process separation of produced p-Xylol, has advantages of that flow process is simple, number of devices is few and investment cost is low.
For addressing the above problem, 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 into and in the raw material that comprises Mixed XYLENE, carry out direct heat exchange, make the vaporization of inertia cryogenic liquid and the cooling raw material that comprises Mixed XYLENE, crystallization high purity p-Xylol crystal in the described raw material that comprises Mixed XYLENE, discharges crystallizer with slurry form.
In technique scheme, preferably, described Mixed XYLENE major ingredient is C8 aromatic hydrocarbons, also can contain on a small quantity the composition such as propyl benzene, C10 aromatic hydrocarbons.
In technique scheme, preferably, described crystallizer service temperature is-47.9 DEG C～13.3 DEG C, more preferably, is-15 DEG C～10 DEG C.
In technique scheme, preferably, described inertia cryogenic liquid is at least one in liquid nitrogen, Liquid carbon dioxide, liquid argon or liquid helium, more preferably, is at least one in liquid nitrogen or Liquid carbon dioxide.
In technique scheme, preferably, in described crystallizer, the crystal weight content of dimethylbenzene slurry is 10～90%, and more preferably, weight content is 20～60%.
In technique scheme, preferably, in described crystallizer, crystallization degree control program is at least one in crystallization control device service temperature, the crystalline content of controlling dimethylbenzene slurry; Described method is operate continuously or periodical operation.
In technique scheme, preferably, describedly can purify recycling from crystallizer expellant gas.
In the present invention, in a crystallizer with agitator, have the Mixed XYLENE raw material of certain liquid level, this burst of Mixed XYLENE raw material initial stage can be all liquid, can be also the slurry that contains part crystal.In Mixed XYLENE stock liquid, directly pass into inertia cryogenic liquid, by with the direct heat exchange of raw material Mixed XYLENE, inertia cryogenic liquid vaporization and raw material Mixed XYLENE is cooling, crystallization high purity p-Xylol crystal in cooling raw material Mixed XYLENE.By service temperature or other processing parameter (as the crystalline content of dimethylbenzene slurry in crystallizer) of crystallization control tank, can guarantee that the crystal major ingredient of separating out is p-Xylol.
Agitator in crystallizer plays a part to help slurry in inertia cryogenic liquid and slurry heat exchange and even mixed crystallization tank on the one hand; Also the crystal of larger particles in crystallizer is played to crushing effect on the other hand.Directly in crystallisation by cooling process, crystal is to form rapidly, easily in crystal, wrap up crystalline mother solution, the crushing effect of agitator can be by out broken apart the crystalline mother solution wrapping up in crystal, further reduce the mother liquor amount of carrying secretly of containing of crystallization, improve the content of p-Xylol in crystal, meanwhile, the slurry that crystal in small, broken bits is also convenient in follow-up solid-liquid separation process is carried.
The working pressure of crystallizer is on the impact of crystallisation process little, and crystallizer is operation under positive pressure generally.
Optionally, after the vaporization of inertia cryogenic liquid, from crystallizer, discharge liquefaction again after recycling.Can save like this consumption of inertia cryogenic liquid.In gas recovery working cycle, need frequently discharge a small amount of gas and supplement fresh inertia cryogenic liquid, prevent the accumulation of impurity in inertia cryogenic liquid.
If under some condition of technology and economy, when after discharging from crystallizer after the vaporization of inertia cryogenic liquid, directly recycling is uneconomical, this portion gas also can be gone to other device or equipment recycling.
Adopt technical process disclosed by the invention, can cancel indirect heat exchange type crystallizer required in traditional crystallization technical process, industrial scale is easily amplified in technical process disclosed in this invention, quantity when required crystallizer quantity adopts indirect heat exchange type crystallizer will greatly reduce, and the cost of manufacture of crystallizer also more traditional indirect heat exchange crystallizer is low, the facility investment expense of device will greatly reduce, and obtain good technique effect.
Brief description of the drawings
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 material feeding tube line; 5 is the Mixed XYLENE slurry discharging pipeline that contains p-Xylol crystal.
In Fig. 1, raw material passes into the crystallizer 1 with agitator by material feeding tube line 4, inertia cryogenic liquid also passes into crystallizer 1 by inertia cryogenic liquid feeding line 2, in crystallizer 1, inertia cryogenic liquid heat absorption vaporization, the gas after heat absorption vaporization is discharged crystallizer 1 by crystallizer gas outlet pipe line 3.Meanwhile, in crystallizer 1, p-Xylol crystal is separated out in the Mixed XYLENE cooling in raw material, and the Mixed XYLENE slurry that contains p-Xylol crystal is discharged crystallizer 1 from pipeline 5.
Below by embodiment, the present invention is further elaborated, but be not limited only to the present embodiment.
Embodiment
Following embodiment is only for the present invention is described further, but these embodiment 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, can make multiple amendment to the present invention.
[embodiment 1]
According to flow process shown in Fig. 1, the raw material that p-Xylol content is 60wt% flows in crystallizer, passes into liquid nitrogen, and crystallization control tank service temperature is near-15 DEG C, and the crystalline content in slurry is about 40wt%.According to the influx of crystallizer service temperature and crystal solid content adjusting liquid nitrogen.The dimethylbenzene slurry that contains p-Xylol crystal 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 slaking of crystal.The output of nitrogen of absorbing heat after vaporization by control, maintains the working pressure of crystallizer in 5 bar (gauge pressure) left and right.
The nitrogen of vaporization uses absorption/desorption tank purifying treatment of two blocked operations, is sent to after liquid nitrogen preparation apparatus liquefies again and is sent to crystallizer after purifying treatment.
[embodiment 2]
According to flow process shown in Fig. 1, the raw material that p-Xylol content is 80wt% flows in crystallizer, passes into liquid nitrogen, and crystallization control tank service temperature is near-10 DEG C, and the crystalline content in slurry is about 30wt%.According to the influx of crystallizer service temperature and crystal solid content adjusting liquid nitrogen.The dimethylbenzene slurry that contains p-Xylol crystal 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 slaking of crystal.The output of nitrogen of absorbing heat after vaporization by control, maintains the working pressure of crystallizer in 2 bar (gauge pressure) left and right.
[embodiment 3]
According to flow process shown in Fig. 1, the raw material that p-Xylol content is 80wt% flows in crystallizer, passes into liquid nitrogen, and crystallization control tank service temperature is near-13.3 DEG C, and the crystalline content in slurry is about 20wt%.According to the influx of crystallizer service temperature and crystal solid content adjusting liquid nitrogen.The dimethylbenzene slurry that contains p-Xylol crystal 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 slaking of crystal.The output of nitrogen of absorbing heat after vaporization by control, maintains the working pressure of crystallizer in 3 bar (gauge pressure) left and right.
[embodiment 4]
According to flow process shown in Fig. 1, the raw material that p-Xylol content is 30wt% flows in crystallizer, passes into liquid nitrogen, and crystallization control tank service temperature is near-47.9 DEG C, and the crystalline content in slurry is about 50wt%.According to the influx of crystallizer service temperature and crystal solid content adjusting liquid nitrogen.The dimethylbenzene slurry that contains p-Xylol crystal 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 slaking of crystal.The output of nitrogen of absorbing heat after vaporization by control, maintains the working pressure of crystallizer in 4 bar (gauge pressure) left and right.
[embodiment 5]
According to flow process shown in Fig. 1, the raw material that p-Xylol content is 50wt% flows in crystallizer, passes into liquid nitrogen, and crystallization control tank service temperature is near-25.2 DEG C, and the crystalline content in slurry is about 60wt%.Regulate the influx of liquid nitrogen according to crystallizer service temperature.The dimethylbenzene slurry that contains p-Xylol crystal 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 slaking of crystal.The output of nitrogen of absorbing heat after vaporization by control, maintains the working pressure of crystallizer in 3.5 bar (gauge pressure) left and right.
[embodiment 6]
According to flow process shown in Fig. 1, the raw material that p-Xylol content is 60wt% flows in crystallizer, passes into Liquid carbon dioxide, and crystallization control tank service temperature is near-15 DEG C, and the crystalline content in slurry is about 40wt%.According to the influx of crystallizer service temperature and crystal solid content adjusting Liquid carbon dioxide.The dimethylbenzene slurry that contains p-Xylol crystal 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 slaking of crystal.The output of carbonic acid gas of absorbing heat after vaporization by control, maintains the working pressure of crystallizer in 5 bar (gauge pressure) left and right.
The carbonic acid gas of vaporization uses absorption/desorption tank purifying treatment of two blocked operations, is sent to after Liquid carbon dioxide preparation apparatus liquefies again and is sent to crystallizer after purifying treatment.
[embodiment 7]
According to flow process shown in Fig. 1, the raw material that p-Xylol content is 80wt% flows in crystallizer, passes into Liquid carbon dioxide, and crystallization control tank service temperature is near-10 DEG C, and the crystalline content in slurry is about 10wt%.According to the influx of crystallizer service temperature and crystal solid content adjusting Liquid carbon dioxide.The dimethylbenzene slurry that contains p-Xylol crystal 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 slaking of crystal.The output of carbonic acid gas of absorbing heat after vaporization by control, maintains the working pressure of crystallizer in 2 bar (gauge pressure) left and right.
Claims (10)
1. the method for a direct crystallisation by cooling separating paraxylene, in the crystallizer with agitator, inertia cryogenic liquid is passed into and in the raw material that comprises Mixed XYLENE, carry out direct heat exchange, make the vaporization of inertia cryogenic liquid and the cooling raw material that comprises Mixed XYLENE, crystallization high purity p-Xylol crystal from the described raw material that comprises Mixed XYLENE, discharges crystallizer with slurry form.
2. a kind of method of direct crystallisation by cooling separating paraxylene according to claim 1, is characterized in that described Mixed XYLENE major ingredient is C8 aromatic hydrocarbons, also can contain on a small quantity the composition such as propyl benzene, C10 aromatic hydrocarbons.
3. a kind of method of direct crystallisation by cooling separating paraxylene according to claim 1, is characterized in that described crystallizer service temperature is-47.9 DEG C～13.3 DEG C.
4. a kind of method of direct crystallisation by cooling separating paraxylene according to claim 3, is characterized in that described crystallizer service temperature is-15 DEG C～10 DEG C.
5. a kind of method of direct crystallisation by cooling separating paraxylene according to claim 1, is characterized in that described inertia cryogenic liquid is at least one in liquid nitrogen, Liquid carbon dioxide, liquid argon or liquid helium.
6. a kind of method of direct crystallisation by cooling separating paraxylene according to claim 1, the crystal weight content that it is characterized in that dimethylbenzene slurry in described crystallizer is 10～90%.
7. a kind of method of direct crystallisation by cooling separating paraxylene according to claim 6, the crystal weight content that it is characterized in that dimethylbenzene slurry in described crystallizer is 20～60%.
8. a kind of method of direct crystallisation by cooling separating paraxylene according to claim 1, is characterized in that in described crystallizer, crystallization degree control program is at least one in crystallization control device service temperature, the crystalline content of controlling dimethylbenzene slurry; Described method is operate continuously or periodical operation.
9. a kind of method of direct crystallisation by cooling separating paraxylene according to claim 5, is characterized in that described inertia cryogenic liquid is at least one in liquid nitrogen or Liquid carbon dioxide.
10. a kind of method of direct crystallisation by cooling separating paraxylene according to claim 1, is characterized in that describedly can purifying recycling from crystallizer expellant gas.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN108794295A (en) * | 2018-05-30 | 2018-11-13 | 重庆三峡学院 | A kind of method of Crystallization Separation paraxylene |
| 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 |
| CN113813638A (en) * | 2021-11-02 | 2021-12-21 | 江西思远再生资源有限公司 | Method for separating water and calcium chloride by eutectic freezing crystallization |
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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 |
| KR20100057522A (en) * | 2008-11-21 | 2010-05-31 | 차이나 페트로리움 앤드 케미컬 코포레이션 | Process for the crystallization separation of p-xylene |
| 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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2013
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Patent Citations (4)
| 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 |
| KR20100057522A (en) * | 2008-11-21 | 2010-05-31 | 차이나 페트로리움 앤드 케미컬 코포레이션 | Process for the crystallization separation of p-xylene |
| CN102060651A (en) * | 2010-11-05 | 2011-05-18 | 华东理工大学 | Method and device for combining and separating mixed xylene slurry |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN108794295A (en) * | 2018-05-30 | 2018-11-13 | 重庆三峡学院 | A kind of method of Crystallization Separation paraxylene |
| 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 |
| CN113813638A (en) * | 2021-11-02 | 2021-12-21 | 江西思远再生资源有限公司 | Method for separating water and calcium chloride by eutectic freezing crystallization |
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