CN108794295B - Method for crystallizing and separating p-xylene - Google Patents
Method for crystallizing and separating p-xylene Download PDFInfo
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- CN108794295B CN108794295B CN201810540066.8A CN201810540066A CN108794295B CN 108794295 B CN108794295 B CN 108794295B CN 201810540066 A CN201810540066 A CN 201810540066A CN 108794295 B CN108794295 B CN 108794295B
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- URLKBWYHVLBVBO-UHFFFAOYSA-N Para-Xylene Chemical group CC1=CC=C(C)C=C1 URLKBWYHVLBVBO-UHFFFAOYSA-N 0.000 title claims abstract description 152
- 238000000034 method Methods 0.000 title claims abstract description 37
- 239000007788 liquid Substances 0.000 claims abstract description 104
- 238000002425 crystallisation Methods 0.000 claims abstract description 69
- 230000008025 crystallization Effects 0.000 claims abstract description 69
- 239000002994 raw material Substances 0.000 claims abstract description 56
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims abstract description 46
- 239000013078 crystal Substances 0.000 claims abstract description 41
- 239000000110 cooling liquid Substances 0.000 claims abstract description 39
- 239000008096 xylene Substances 0.000 claims abstract description 36
- 238000009833 condensation Methods 0.000 claims description 25
- 230000005494 condensation Effects 0.000 claims description 25
- 238000000926 separation method Methods 0.000 claims description 23
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 14
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 14
- 150000004945 aromatic hydrocarbons Chemical class 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 11
- 238000007789 sealing Methods 0.000 claims description 11
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 7
- 239000001569 carbon dioxide Substances 0.000 claims description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims description 7
- 238000012546 transfer Methods 0.000 claims description 5
- 239000002244 precipitate Substances 0.000 claims description 2
- 230000009286 beneficial effect Effects 0.000 abstract description 3
- 238000013461 design Methods 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- 239000012466 permeate Substances 0.000 abstract description 2
- 238000004904 shortening Methods 0.000 abstract 1
- 238000011084 recovery Methods 0.000 description 9
- IVSZLXZYQVIEFR-UHFFFAOYSA-N m-xylene Chemical group CC1=CC=CC(C)=C1 IVSZLXZYQVIEFR-UHFFFAOYSA-N 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 4
- WOZVHXUHUFLZGK-UHFFFAOYSA-N dimethyl terephthalate Chemical compound COC(=O)C1=CC=C(C(=O)OC)C=C1 WOZVHXUHUFLZGK-UHFFFAOYSA-N 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 238000007599 discharging Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 229920000728 polyester Polymers 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- ODLMAHJVESYWTB-UHFFFAOYSA-N propylbenzene Chemical compound CCCC1=CC=CC=C1 ODLMAHJVESYWTB-UHFFFAOYSA-N 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229940078552 o-xylene Drugs 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/14—Purification; Separation; Use of additives by crystallisation; Purification or separation of the crystals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/0004—Crystallisation cooling by heat exchange
- B01D9/0013—Crystallisation cooling by heat exchange by indirect heat exchange
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D2009/0086—Processes or apparatus therefor
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Water Supply & Treatment (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention belongs to the technical field of paraxylene crystallization, and particularly relates to a method for crystallizing and separating paraxylene. The invention leads the condensing pipe to shuttle inside and outside the crystallizing tank, and simultaneously carries out heat exchange and temperature reduction on the mixed xylene liquid raw material from the inside and the outside, and simultaneously leads the inert cooling liquid to gradually and slowly permeate into the crystallizing tank from different heights in the micro-flowing process due to the design of the flowing liquid micropores, thereby not causing great disturbance to the raw material liquid, being beneficial to the growth of crystals, improving the purity and the yield of the crystals, shortening the crystallizing time and improving the production intensity of equipment.
Description
Technical Field
The invention belongs to the technical field of paraxylene crystallization, and particularly relates to a method for separating paraxylene by crystallization.
Background
Para-xylene is an important raw material in the polyester industry, and is mainly used for producing purified terephthalic acid or purified dimethyl terephthalate, and then the purified terephthalic acid or purified dimethyl terephthalate is used for producing polyester. During the production of paraxylene, a mixture of paraxylene, metaxylene, orthoxylene, ethylbenzene, and the like is produced. At present, the process flow of the industrialized separation of the paraxylene mainly comprises an adsorption separation method and a crystallization separation method. Crystallization is one of the common methods for separating paraxylene because of the small and large differences in boiling point between the components of a mixture containing paraxylene.
Chinese patent CN 104030880B discloses a method for separating p-xylene by direct cooling crystallization, which comprises storing a liquid raw material of mixed xylene at a certain liquid level in a crystallization tank with a stirrer, introducing an inert cryogenic liquid into the raw material containing mixed xylene to perform direct heat exchange, vaporizing the inert cryogenic liquid to cool the raw material containing p-xylene, crystallizing high-purity p-xylene crystals from the raw material containing mixed xylene, and discharging the crystallized high-purity p-xylene crystals out of the crystallization tank in the form of slurry. The technical scheme simplifies the crystallization separation process and equipment consumption of paraxylene, and particularly has good separation effect on mixed xylene liquid raw materials containing C8 arene, propyl benzene and C10 arene components. However, the method directly introduces a large amount of low-temperature liquid into the mixed xylene liquid raw material from the bottom of the crystallization tank, and the low-temperature liquid and the raw material liquid can cause great disturbance to the raw material liquid in the mixing process, so that the method is not beneficial to the growth of crystals and influences the crystallization efficiency.
Disclosure of Invention
The method for crystallizing and separating p-xylene solves the problems that in the prior art, a large disturbance is caused to raw material liquid in the process of mixing low-temperature liquid and the raw material liquid, the growth of crystals is not facilitated, and the crystallization efficiency is influenced.
The invention aims to provide a method for separating p-xylene by crystallization, and the structure of a device for separating p-xylene by crystallization is as follows: comprises a crystallizing tank and a condensing pipe, wherein the upper end of the crystallizing tank is provided with a feed inlet and an exhaust outlet, the lower end is provided with a discharge outlet, the crystallizer is provided with a first side wall and a second side wall which are opposite to each other at the left and right, a row of first through holes are longitudinally arranged along the first side wall, a row of second through holes are longitudinally arranged along the second side wall, and the first through hole and the second through hole form a pair of through holes in pairs from top to bottom, the condensation pipe sequentially passes through the pair of through holes, the head end pipe orifice of the condensing pipe is positioned outside the lower end of the crystallizing tank and is called a liquid inlet, the tail end pipe orifice is positioned outside the upper end of the crystallizing tank and is called a liquid outlet, a plurality of pipes of the condensation pipe, which are positioned in the crystallization tank, are called inner condensation pipes, a plurality of liquid flow micropores are formed in the inner condensation pipes, and the joint of the condensation pipe and the crystallization tank is sealed through a sealing device;
the crystallization separation operation steps are as follows:
the liquid inlet and the liquid outlet are sealed, mixed xylene liquid raw materials are introduced into the crystallizing tank from the feed inlet, then the feed inlet is sealed, inert cooling liquid is introduced into the condensing pipe from the liquid inlet, the inert cooling liquid flows out of the liquid outlet along the condensing pipe, part of the inert cooling liquid flows into the crystallizing tank from each flow liquid micropore, and the inert cooling liquid and the mixed xylene liquid raw materials are subjected to direct heat exchange, so that paraxylene is crystallized, crystals are separated out, and then the materials are discharged through the discharge outlet to recover the paraxylene crystals.
Preferably, in the method for separating paraxylene by crystallization, the first through hole and the second through hole are opposite to each other in position, and two groups of through holes are paired.
Preferably, in the method for separating paraxylene by crystallization, the first through hole and the second through hole are staggered one by one, and a connecting line between a pair of through holes formed by two is inclined relative to the vertical axis of the crystallization tank.
Preferably, in the method for separating paraxylene by crystallization, the flow liquid micropores have a pore diameter of 0.5-10 mm.
Preferably, in the method for separating paraxylene by crystallization, the sealing device is a sealing ring embedded between the crystallization tank and the condensation pipe.
Preferably, in the method for separating p-xylene by crystallization, when the inert cooling liquid in the condensation pipe overflows from the liquid outlet, the introduction of the inert cooling liquid is stopped, so that the inert cooling liquid gradually and slowly flows into the mixed xylene liquid raw material from the liquid flow micropores, and the raw material is cooled for heat exchange; when the flow of the inert cooling liquid in the condensation pipe is finished, the operations are repeated until the crystallization separation operation is finished.
Preferably, in the method for separating p-xylene by crystallization, the inert cooling liquid is liquid nitrogen or liquid carbon dioxide.
Preferably, in the method for separating para-xylene by crystallization, the mixed xylene liquid raw material mainly comprises C8 aromatic hydrocarbon and C10 aromatic hydrocarbon, and the mass fraction of the mixed xylene liquid raw material is 5-95%.
Compared with the prior art, the method for separating p-xylene by crystallization has the following beneficial effects:
in order to solve the problems proposed in the background art, the invention designs a special device for crystallizing and separating paraxylene and a corresponding method. Through shuttling the condenser pipe inside and outside the crystallizer, carry out the heat transfer cooling to mixing xylene liquid raw materials simultaneously from inside and outside, simultaneously because the design of flowing liquid micropore makes the inert cooling liquid slowly permeate the crystallizer from different heights in little flowing process gradually, can not cause raw materials liquid to cause great disturbance, is favorable to the growth of crystal, has improved crystallization purity and rate of recovery, practices thrift the crystallization time, improves crystallization efficiency. In addition, the feed inlet is used for introducing mixed xylene liquid raw materials, the exhaust outlet is used for exhausting, and the discharge outlet is used for discharging.
The diameter of the flow liquid micropore is controlled to be 0.5-10mm so as to ensure that the inert cooling liquid can be fully flowed to the liquid outlet of the condensing pipe to be discharged, and the inert cooling liquid is also flowed into the crystallizing tank from different heights, so that the liquid disturbance is reduced, and the heat transfer efficiency is improved.
Drawings
FIG. 1 is a schematic structural appearance of an apparatus for the crystallization separation of paraxylene according to the present invention;
FIG. 2 is a schematic view of a first structure of the apparatus for the crystallization separation of paraxylene of the present invention;
FIG. 3 is a schematic diagram of a second configuration of the apparatus for the crystallographic separation of para-xylene according to the invention;
FIG. 4 is a schematic view showing the connection of a crystallizing tank and a condensing pipe of the apparatus for the crystallization separation of paraxylene of the present invention.
Description of reference numerals:
1. the device comprises a crystallizing tank, 11 feed inlets, 12 exhaust ports, 13 discharge outlets, 14 first through holes, 15 second through holes, 2 liquid inlets, 21 liquid flow micropores, 3 liquid outlets, 4 internal condensation pipes and 5 external condensation pipes.
Detailed Description
The present invention is described in detail below with reference to specific examples, but the present invention should not be construed as being limited thereto. The test methods in the following examples, which are not specified in specific conditions, are generally conducted under conventional conditions, and the steps thereof will not be described in detail since they do not relate to the invention.
Example 1
A method for separating para-xylene by crystallization is disclosed, and the structure of the device for separating para-xylene by crystallization is shown in figures 1-2 and figure 4, and is as follows: comprises a crystallizing tank 1 and a condenser pipe, the upper end of the crystallizing tank 1 is provided with a feed inlet 11 and an exhaust port 12, the lower end of the crystallizing tank 1 is provided with a discharge outlet 13, the crystallizing tank 1 is provided with a first side wall and a second side wall which are opposite to each other, a row of first through holes 14 are longitudinally arranged along the first side wall, a row of second through holes 15 are longitudinally arranged along the second side wall, the first through holes 14 and the second through holes 15 form a pair of through holes in a pairwise manner from top to bottom, a plurality of pairs of through holes are formed totally, the condenser pipe sequentially penetrates through the paired through holes to form a liquid passage, a head end pipe orifice of the condenser pipe is positioned outside the lower end of the crystallizing tank 1 and is called as a liquid inlet 2, a tail end pipe orifice of the condenser pipe is positioned outside the upper end of the crystallizing tank 1 and is called as a liquid outlet 3, a plurality of pipes of the condenser pipe positioned in the crystallizing tank 1, the inner condenser pipe 4 is provided with a plurality of liquid flow micropores 41, and the joint of the condenser pipe and the crystallizing tank 1 is sealed by a sealing device;
the crystallization separation operation steps are as follows:
In embodiment 1, the first through holes 14 and the second through holes 15 are positioned one-to-one, and two sets of paired through holes. The diameter of the flow liquid micropore 41 is 0.5mm, and the sealing device is a sealing ring which is embedded between the crystallization tank 1 and the condensation pipe. The surface of the sealing ring is coated with an inert material coating, and the sealing ring is welded between the crystallization tank 1 and the condensation pipe in a sealing mode. The inert cooling liquid is liquid nitrogen. The main components of the mixed xylene liquid raw material are C8 aromatic hydrocarbon meta-xylene, ortho-xylene and C10 aromatic hydrocarbon, and the mass fraction of the mixed xylene liquid raw material para-xylene is 75%.
In example 1, the temperature of liquid nitrogen is controlled to be about-13 ℃, when the content of crystals in the crystallization tank 1 reaches 65% of the quality of raw materials, the materials are discharged, the crystals are recovered, and the purity of p-xylene in the finally measured crystals is 99.8%; and (3) continuously adding the residual liquid after the crystals are recovered as a raw material into the crystallizing tank 1, and continuously crystallizing and separating until no crystals are separated out from the mixed xylene liquid raw material, wherein the final total recovery rate of the p-xylene is 94.0%.
Example 2
A method for separating para-xylene by crystallization, the structure of the device for separating para-xylene by crystallization is basically the same as that of the embodiment 1, except that: in example 2, the first through holes 14 and the second through holes 15 are staggered one by one, and the line connecting a pair of through holes formed two by two is inclined by 70 degrees with respect to the vertical axis of the crystallization tank 1. The flow cell 41 has a pore diameter of 2 mm. The structure of the apparatus for the separation by crystallization of paraxylene in example 2 is shown in FIG. 1 and FIGS. 3 to 4.
The crystallization separation operation was substantially the same as in example 1 except that: in example 2, the inert cooling liquid is liquid carbon dioxide. The main components of the mixed xylene liquid raw material are C8 aromatic hydrocarbon meta-xylene, ortho-xylene and C10 aromatic hydrocarbon, and the mass fraction of the mixed xylene liquid raw material para-xylene is 63%.
In example 2, the temperature of liquid carbon dioxide was controlled to about-10 ℃, and when the content of crystals in the crystallizer 1 reached 30% of the mass of the raw material, the material was discharged and the crystals were recovered, and the purity of p-xylene in the last crystals was 99.8%; and (3) continuously adding the residual liquid after the crystals are recovered as a raw material into the crystallizing tank 1, and continuously crystallizing and separating until no crystals are separated out from the mixed xylene liquid raw material, wherein the final total recovery rate of the p-xylene is 94.0%.
Example 3
A method for separating p-xylene by crystallization has the same structure as that of example 1.
The crystallization separation operation was substantially the same as in example 1 except that: in example 2, the inert cooling liquid is liquid carbon dioxide. The main components of the mixed xylene liquid raw material are C8 aromatic hydrocarbon meta-xylene, ortho-xylene and C10 aromatic hydrocarbon, and the mass fraction of the mixed xylene liquid raw material is 5 percent.
In example 3, the temperature of liquid carbon dioxide was controlled to about-10 ℃, and when the content of crystals in the crystallizer 1 reached 4.5% of the mass of the raw material, the material was discharged and the crystals were recovered, and the purity of p-xylene in the last crystals was 99.8%; the overall final para-xylene recovery was 94.3%.
It should be noted that, in order to avoid excessive disturbance of the raw material, when the inert cooling liquid in the condensation pipe overflows the liquid outlet 3, the inert cooling liquid is stopped to be introduced, so that the inert cooling liquid gradually and slowly flows into the mixed xylene liquid raw material from the liquid flow micropores 41, and the raw material is cooled and subjected to heat exchange; and after the inert cooling liquid in the condensation pipe flows out, repeating the operations of introducing the inert cooling liquid, stopping introducing the inert cooling liquid and discharging the inert cooling liquid until the crystallization separation operation is finished.
Example 4
A method for separating p-xylene by crystallization has the same structure as that of example 1.
The crystallization separation operation was substantially the same as in example 1 except that: in example 2, the mixed xylene liquid feedstock had main components of m-xylene, o-xylene and C10 aromatic hydrocarbons, which are C8 aromatic hydrocarbons, and the mass fraction of p-xylene, which is a mixed xylene liquid feedstock, was 95%.
In example 4, the temperature of liquid carbon dioxide was controlled to about-10 ℃, and when the content of crystals in the crystallizer 1 reached 75% of the mass of the raw material, the material was discharged and the crystals were recovered, and the purity of p-xylene in the last crystals was 99.8%; the overall final para-xylene recovery was 93.7%.
Comparative example 1
A method for crystallizing and separating paraxylene, namely a method in the embodiment 3 of Chinese patent CN 104030880B for crystallizing and separating mixed xylene liquid raw material in the embodiment 1. In comparative example 1, the temperature of liquid nitrogen is controlled to be about-13 ℃, when the content of crystals in the crystallization tank 1 reaches 65% of the quality of the raw materials, the materials are discharged, the crystals are recovered, and finally, the purity of paraxylene in the crystals is 98.9%; and (3) continuously adding the residual liquid after the crystals are recovered as a raw material into a crystallization tank, and continuously crystallizing and separating until no crystals are separated out from the mixed xylene liquid raw material, wherein the final total recovery rate of the p-xylene is 90.1%. The purity and overall recovery were less effective than example 1.
Comparative example 2
A method for separating p-xylene by crystallization is characterized in that the structure of a device for separating p-xylene by crystallization is as follows: including crystallizer and condenser pipe, the upper end of crystallizer is provided with feed inlet and gas vent, and the lower extreme of crystallizer is provided with the discharge gate, and condenser pipe spiral winding is installed on the crystallizer outer wall.
The crystallization separation operation steps are as follows:
mix xylene liquid raw materials from the feed inlet to the crystallizer in, then seal the feed inlet, with the inert cooling liquid from letting in the inlet of condenser pipe lower extreme, flow in condenser pipe upper end liquid outlet, the inert cooling liquid carries out direct heat transfer with mixing xylene liquid raw materials to make the paraxylene crystallization, separate out the crystal, then through discharge gate discharge material, retrieve the paraxylene crystal.
In comparative example 2, the inert cooling liquid was liquid nitrogen, the temperature of the liquid nitrogen was controlled to about-13 ℃, when the content of crystals in the crystallizer reached 65% of the mass of the raw material, the material was discharged and the crystals were recovered, and the purity of p-xylene in the last crystals was 99.3%; and (3) continuously adding the residual liquid after the crystals are recovered as a raw material into a crystallization tank, and continuously crystallizing and separating until no crystals are separated out from the mixed xylene liquid raw material, wherein the final total recovery rate of the p-xylene is 85.3%. The purity and the total recovery rate are both inferior to those of example 1, and comparative example 2 takes 2 times as long as example 1 because the heat exchange is conducted by condensation outside the crystallization tank.
It should be noted that the number of the inner condensation pipes 4, the number of the outer condensation pipes 5 and the number of the upper stream micropores 41 of the inner condensation pipes 4 in the structure of the apparatus for separating para-xylene by crystallization according to the present invention are selected according to actual conditions, and in the above embodiments 1 to 4, the number of the condensation pipes 4 is 5, and the number of the outer condensation pipes 5 is 4; the number of the fine holes 41 for the upstream liquid of the inner condenser tube 4 is 20, and the fine holes are spirally distributed around the inner condenser tube 4.
It should be noted that when numerical ranges are given herein, it is understood that both endpoints of each of the numerical ranges and any number between the endpoints are optional unless the invention otherwise specifically states. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (7)
1. The method for separating p-xylene by crystallization is characterized in that the structure of a device for separating p-xylene by crystallization is as follows: the device comprises a crystallizing tank (1) and a condenser pipe, wherein a feed inlet (11) and an exhaust port (12) are formed in the upper end of the crystallizing tank (1), a discharge outlet (13) is formed in the lower end of the crystallizing tank, the crystallizing tank (1) is provided with a first side wall and a second side wall which are opposite to each other in the left-right direction, a row of first through holes (14) are longitudinally formed in the first side wall, a row of second through holes (15) are longitudinally formed in the second side wall, a pair of through holes are formed in the first through holes (14) and the second through holes (15) in a pairwise mode from top to bottom, the condenser pipe sequentially penetrates through the paired through holes, a head end pipe orifice of the condenser pipe is located outside the lower end of the crystallizing tank (1) and is called a liquid inlet (2), a tail end pipe orifice is located outside the upper end of the crystallizing tank (1) and is called a liquid outlet (3), and a plurality of pipes, a plurality of liquid flow micropores (41) are formed in the inner condensation pipe (4), the diameter of each liquid flow micropore (41) is 0.5-10mm, and the joint of the condensation pipe and the crystallization tank (1) is sealed through a sealing device;
the crystallization separation operation steps are as follows:
will with inlet (2) with liquid outlet (3) seal, follow feed inlet (11) to let in mixed xylene liquid raw materials in crystallizer (1), then seal feed inlet (11) are followed inert cooling liquid inlet (2) let in the condenser pipe, inert cooling liquid flows along the condenser pipe in liquid outlet (3), partial inert cooling liquid flows in from each liquid micropore (41) crystallizer (1), inert cooling liquid and mixed xylene liquid raw materials carry out direct heat transfer to make the crystallization of paraxylene, precipitate the crystal, then discharge the material through discharge gate (13), retrieve paraxylene crystal.
2. The crystalline separation method for paraxylene according to claim 1, characterized in that said first through holes (14) and said second through holes (15) are positioned one opposite to the other, two sets of paired holes.
3. The process for the crystallographic separation of para-xylene according to claim 1, characterized in that said first and second perforation holes (14, 15) are positioned one by one staggered, the connection between a pair of perforations consisting of two being inclined with respect to the vertical axis of the crystallization tank (1).
4. The method for the crystalline separation of paraxylene according to claim 1, characterized in that said sealing means is a gasket inserted between said crystallization tank (1) and said condensation duct.
5. The method for crystallizing and separating the paraxylene according to any one of claims 1 to 4, characterized in that when the inert cooling liquid in the condensation pipe overflows the liquid outlet (3), the introduction of the inert cooling liquid is stopped, so that the inert cooling liquid gradually and slowly flows into the mixed xylene liquid raw material from the liquid flow micropores (41) to cool and exchange heat with the raw material; when the flow of the inert cooling liquid in the condensation pipe is finished, the operations are repeated until the crystallization separation operation is finished.
6. The method for crystallizing and separating p-xylene according to any one of claims 1 to 4, wherein the inert cooling liquid is liquid nitrogen or liquid carbon dioxide.
7. The method for separating para-xylene through crystallization as claimed in any one of claims 1 to 4, wherein the mixed xylene liquid raw material comprises C8 aromatic hydrocarbons and C10 aromatic hydrocarbons as main components, and the mass fraction of para-xylene in the mixed xylene liquid raw material is 5-95%.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810540066.8A CN108794295B (en) | 2018-05-30 | 2018-05-30 | Method for crystallizing and separating p-xylene |
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| CN201810540066.8A CN108794295B (en) | 2018-05-30 | 2018-05-30 | Method for crystallizing and separating p-xylene |
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| CN108794295B true CN108794295B (en) | 2021-01-08 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3801285A (en) * | 1968-09-04 | 1974-04-02 | E Meisenburg | Apparatus for receiving crystals |
| CN104030880A (en) * | 2013-08-08 | 2014-09-10 | 中石化上海工程有限公司 | Method for directly cooling, crystallizing and separating paraxylene |
| CN205759825U (en) * | 2016-05-18 | 2016-12-07 | 江西洪安化工有限公司 | A kind of chemical industry crystallization kettle of improvement |
-
2018
- 2018-05-30 CN CN201810540066.8A patent/CN108794295B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3801285A (en) * | 1968-09-04 | 1974-04-02 | E Meisenburg | Apparatus for receiving crystals |
| CN104030880A (en) * | 2013-08-08 | 2014-09-10 | 中石化上海工程有限公司 | Method for directly cooling, crystallizing and separating paraxylene |
| CN205759825U (en) * | 2016-05-18 | 2016-12-07 | 江西洪安化工有限公司 | A kind of chemical industry crystallization kettle of improvement |
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| CN108794295A (en) | 2018-11-13 |
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