CN114394880A - Method for extracting high-purity 2-methylnaphthalene from wash oil - Google Patents
Method for extracting high-purity 2-methylnaphthalene from wash oil Download PDFInfo
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- CN114394880A CN114394880A CN202210135569.3A CN202210135569A CN114394880A CN 114394880 A CN114394880 A CN 114394880A CN 202210135569 A CN202210135569 A CN 202210135569A CN 114394880 A CN114394880 A CN 114394880A
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- QIMMUPPBPVKWKM-UHFFFAOYSA-N 2-methylnaphthalene Chemical compound C1=CC=CC2=CC(C)=CC=C21 QIMMUPPBPVKWKM-UHFFFAOYSA-N 0.000 title claims abstract description 89
- 238000000034 method Methods 0.000 title claims abstract description 62
- QPUYECUOLPXSFR-UHFFFAOYSA-N 1-methylnaphthalene Chemical compound C1=CC=C2C(C)=CC=CC2=C1 QPUYECUOLPXSFR-UHFFFAOYSA-N 0.000 claims abstract description 60
- 238000002425 crystallisation Methods 0.000 claims abstract description 27
- 230000008025 crystallization Effects 0.000 claims abstract description 26
- 230000008569 process Effects 0.000 claims abstract description 26
- 238000010533 azeotropic distillation Methods 0.000 claims abstract description 23
- 239000012043 crude product Substances 0.000 claims abstract description 11
- 238000002156 mixing Methods 0.000 claims abstract description 6
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 27
- 238000004821 distillation Methods 0.000 claims description 26
- 239000000203 mixture Substances 0.000 claims description 25
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 claims description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 23
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 claims description 18
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 claims description 18
- 238000000926 separation method Methods 0.000 claims description 18
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 claims description 16
- 239000012071 phase Substances 0.000 claims description 13
- 239000013078 crystal Substances 0.000 claims description 10
- 150000001875 compounds Chemical class 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 9
- 230000035900 sweating Effects 0.000 claims description 8
- 238000004064 recycling Methods 0.000 claims description 7
- ATHHXGZTWNVVOU-UHFFFAOYSA-N N-methylformamide Chemical compound CNC=O ATHHXGZTWNVVOU-UHFFFAOYSA-N 0.000 claims description 6
- 230000012010 growth Effects 0.000 claims description 6
- 238000000746 purification Methods 0.000 claims description 6
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- 238000010309 melting process Methods 0.000 claims description 3
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- TXCDCPKCNAJMEE-UHFFFAOYSA-N dibenzofuran Chemical compound C1=CC=C2C3=CC=CC=C3OC2=C1 TXCDCPKCNAJMEE-UHFFFAOYSA-N 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
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- NIHNNTQXNPWCJQ-UHFFFAOYSA-N fluorene Chemical compound C1=CC=C2CC3=CC=CC=C3C2=C1 NIHNNTQXNPWCJQ-UHFFFAOYSA-N 0.000 description 2
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- SHUZOJHMOBOZST-UHFFFAOYSA-N phylloquinone Natural products CC(C)CCCCC(C)CCC(C)CCCC(=CCC1=C(C)C(=O)c2ccccc2C1=O)C SHUZOJHMOBOZST-UHFFFAOYSA-N 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
- C07C7/005—Processes comprising at least two steps in series
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
- C07C7/05—Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds
- C07C7/06—Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds by azeotropic distillation
-
- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Water Supply & Treatment (AREA)
- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a method for extracting high-purity 2-methylnaphthalene from wash oil, wherein the wash oil is rectified and separated to obtain methylnaphthalene enriched fraction; introducing the methylnaphthalene enriched fraction into an azeotropic distillation tower for azeotropic distillation to obtain azeotropic distillate; introducing the azeotropic distillate into a separator to obtain a crude product of 2-methylnaphthalene; and (3) introducing the crude product of the 2-methylnaphthalene into a plurality of batch type melting crystallizers arranged in parallel to crystallize and purify the 2-methylnaphthalene. The method for recovering the entrainer by combining water extraction and ultrasonic mixing has the advantages of low cost, simple process, low impurity content in the entrainer and low entrainer entrainment in the crude product of the 2-methylnaphthalene. The technological process of the invention realizes continuous operation, has high production efficiency and low operation cost, does not involve strong acid and strong alkali, has no pollution in the technological process, and is green and environment-friendly. The method extracts the 2-methylnaphthalene through azeotropic distillation and melt crystallization, and the obtained product has high purity and high yield.
Description
Technical Field
The invention belongs to the technical field of fine chemical separation and refining, and particularly relates to a method for extracting 2-methylnaphthalene based on azeotropic distillation and melt crystallization.
Background
2-methylnaphthalene, also called beta-methylnaphthalene, is an important fine chemical and organic chemical raw material and has wide application. The 2-methylnaphthalene is mainly derived from coal tar washing oil fraction, petroleum cracking byproduct tar and heavy aromatic hydrocarbon, and is widely applied to industries such as medicine, dye, photosensitive material, rubber, plastic, agricultural feed, novel high polymer material and the like. The 2-methylnaphthalene can be used for producing fine chemical products such as vitamin K, textile auxiliary agents, water reducing agents, plant growth regulators, surfactants, lubricants, feed additives and the like.
Due to the complexity of the coal tar wash oil fraction, it is difficult to obtain a 2-methylnaphthalene product meeting the purity requirement from the wash oil fraction by using a single process for separating and refining fine chemicals. The single methods for separating or purifying fine chemicals mainly include rectification, azeotropic rectification, alkylation, acid-base washing, isomerization, solvent recrystallization, solvent extraction, and freeze crystallization. The existing process technology for separating and refining 2-methylnaphthalene from coal tar or wash oil fraction is a combination of the methods, and various separation and refining technologies for 2-methylnaphthalene are formed according to the difference of raw materials, the difference of product purity requirements and specific equipment conditions.
The prior art discloses a method for separating 2-methylnaphthalene from reformed heavy aromatic oil with the methylnaphthalene content being not less than 50 percent, the method is intermittent operation, but is not easy to amplify engineering, and solvent is easy to be entrained in a product due to solvent washing or solvent recrystallization. The method has the defects of more distillation towers, high energy consumption, deficient rectification separation effect, low product purity and low yield.
Due to the complexity of the coal tar wash oil fraction, it is difficult to obtain a 2-methylnaphthalene product meeting the purity requirement from the wash oil fraction by using a single process for separating and refining fine chemicals. The single methods for separating or purifying fine chemicals mainly include rectification, azeotropic rectification, alkylation, acid-base washing, isomerization, solvent recrystallization, solvent extraction, and freeze crystallization. These methods can be classified into two major types, physical methods, mainly rectification, crystallization and extraction, and chemical methods, mainly alkylation, isomerization and chemical refining. The chemical method has high cost and complex process; physical methods such as common rectification methods have high energy consumption and poor separation effect, and crystallization methods usually adopt intermittent operation, have high labor intensity and low production efficiency, so that improvement, perfection and optimized combination of the methods are necessary to exert the respective advantages of the methods, and a novel process method for separating and refining 2-methylnaphthalene with high production efficiency and high product purity is provided.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.
The invention aims to provide a method for extracting high-purity 2-methylnaphthalene from coal tar wash oil, which aims to solve the problems of low production efficiency, complex process, low product purity and yield, serious pollution, serious equipment corrosion and the like in the existing 2-methylnaphthalene separation and refining process.
The embodiment of the application provides a method for extracting high-purity 2-methylnaphthalene from wash oil, which comprises the following steps:
s1, rectifying and separating the wash oil to obtain methylnaphthalene enriched fraction;
s2, introducing the methylnaphthalene enriched fraction into an azeotropic distillation tower for azeotropic distillation to obtain an azeotropic distillate;
s3, introducing the azeotropic distillate into a separator to obtain a crude product of 2-methylnaphthalene;
s4, introducing the crude 2-methylnaphthalene into a plurality of batch type melt crystallizers arranged in parallel to crystallize and purify the 2-methylnaphthalene.
In some embodiments, in step S1, the wash oil is separated by distillation through an atmospheric distillation tower to obtain a naphthalene fraction light oil, a methylnaphthalene enriched fraction and a heavy distillate oil, wherein a part of the heavy distillate oil is recycled to the atmospheric distillation tower, and another part of the heavy distillate oil is recycled.
In some embodiments, in step S2, the methylnaphthalene-rich fraction and the entrainer are mixed in proportion, and the mixture is heated to a certain temperature and then enters an azeotropic distillation tower for azeotropic distillation.
In some embodiments, the entrainer is a single compound entrainer or a mixture type entrainer, wherein the single compound entrainer is any one of ethylene glycol, diethylene glycol, ethanolamine, diethylene glycol, N-methylformamide, the mixture type entrainer is a mixture of heptane and ethanolamine or a mixture of heptane and ethylene glycol;
when a single compound entrainer is adopted, the mass ratio of the methyl naphthalene enriched distillate oil to the entrainer is 1-3: 1; when the mixture type entrainer is adopted, the mass ratio of heptane to ethanolamine or heptane to ethylene glycol in the mixture type entrainer is 0.2-1: 1, and the mass ratio of the methylnaphthalene-enriched distillate oil to the entrainer is 1: 0.8-2.
In some embodiments, in step S3, the azeotropic distillate and water are introduced into an ultrasonic static mixer to be ultrasonically mixed, and then introduced into a separator to be subjected to standing separation of oil and water, and an aqueous phase and an oil phase are separated from the separator, wherein the aqueous phase is an entrainer and water, the aqueous phase enters a rectifying tower to be subjected to distillation separation of the entrainer and water, and the separated entrainer is returned to step S2 and mixed with the methylnaphthalene-enriched fraction for recycling; the separated water is returned to be mixed with the azeotropic distillate for recycling; and the oil phase is a crude product of 2-methylnaphthalene, and the oil phase enters an intermittent melt crystallizer to carry out crystallization and purification on the 2-methylnaphthalene.
In some embodiments, there are 2 batch melt crystallizers in said step S4.
In some embodiments, the naphthalene fraction light oil is obtained from the top of an atmospheric distillation tower, the methylnaphthalene-enriched fraction is obtained from the side of the atmospheric distillation tower, the heavy distillate oil is obtained from the bottom of the atmospheric distillation tower, the temperature of the top of the atmospheric distillation tower is 210-225 ℃, the temperature of the side of the atmospheric distillation tower is 235-260 ℃, and the temperature of the bottom of the atmospheric distillation tower is 290-310 ℃.
In some embodiments, the overhead temperature of the azeotropic distillation tower is 150-175 ℃, the overhead pressure is 1-4 KPa, and the reflux ratio is 5-15; the temperature of the tower bottom is 220-245 ℃, and the pressure of the tower bottom is 10-15 KPa.
In some embodiments, in the step S4, the initial temperature in the crystal growth process is 35 to 40 ℃, the cooling rate is 3 to 8 ℃/h, the final temperature is 8 to 12 ℃, and the constant temperature time is 0.5 to 1 h; the heating rate in the sweating process is 2-6 ℃/h, and the final temperature is 30-32 ℃; the heating rate in the melting process is 2-8 ℃/h, the final temperature is 45-50 ℃, and the final temperature constant-temperature time is 0.5-1 h.
In some embodiments, the separator has an operating temperature of 50 to 80 ℃ and a standing time of 0.2 to 1 hour.
The invention has the beneficial effects that:
(1) the method for recovering the entrainer by combining water extraction and ultrasonic mixing has the advantages of low cost, simple process, low impurity content in the entrainer and low entrainer entrainment in the crude product of the 2-methylnaphthalene.
(2) The technological process of the invention realizes continuous operation, and has high production efficiency and low operation cost.
(3) The invention does not relate to strong acid and strong alkali, and the process is pollution-free and environment-friendly.
(4) The method extracts the 2-methylnaphthalene through azeotropic distillation and melt crystallization, and the obtained product has high purity and high yield.
(5) The azeotropic distillation tower adopts a concentric tube precise fractionating column, has high theoretical plate number, good heat and mass transfer effects, reduced pressure and high separation efficiency; the melting crystallizer well solves the problem that crystal layers are easy to fall off in the crystallization process and the sweating process through special design.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent from and readily appreciated by reference to the following description of the embodiments taken in conjunction with the accompanying drawings,
wherein:
FIG. 1 is a flow chart of a process for extracting high-purity 2-methylnaphthalene from wash oil according to an embodiment of the present invention;
FIG. 2 is a schematic view showing the structure of a rectification column of an azeotropic rectification column in an embodiment of the present invention;
FIG. 3 is a schematic view of the structure of a batch type melt crystallizer in an embodiment of the present invention;
FIG. 4 is a schematic view of a crystallization plate according to an embodiment of the present invention;
reference numerals:
1-washing oil; 2-naphthalene distillate light oil; 3-methylnaphthalene enriched fraction; 4-heavy oil fraction; 5-azeotropic distillate; 6-residual oil; 7-entrainer mixture; 8-2-methylnaphthalene crude product; 9-water; 10-entrainer; 11-heating the cooling medium; 12-residual mother liquor; 13-2-methylnaphthalene product; 14-temperature control medium outlet; 15-temperature control medium inlet; 16-material inlet; 17-a material outlet; 18-inlet of temperature control medium of crystallization plate; 19-outlet of temperature control medium of crystallization plate; 20-bulge; 21-a groove; 22-a helical groove;
v1-washing oil storage tank; v2-atmospheric distillation column; v3-azeotropic distillation column; v4-ultrasonic static mixer; v5-separator; v6-rectifying column; v7-digital temperature controlled oil bath; v8-batch melt crystallizer.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings in conjunction with specific embodiments.
The embodiment of the application provides a method for extracting high-purity 2-methylnaphthalene from wash oil, which comprises the following steps as shown in figure 1:
(1) rectification separation of wash oil
Adding the wash oil 1 into a wash oil storage tank V1, stirring and mixing, then sending the wash oil 1 into an atmospheric distillation tower V2 by a pump, rectifying and separating the wash oil 1, and obtaining the naphthalene fraction light oil 2 at the tower top, wherein the naphthalene fraction light oil can be used as a raw material for extracting naphthalene and can also be recycled to the atmospheric distillation tower V2; the side stream obtains methylnaphthalene enriched fraction 3, the bottom extract is heavy distillate oil 4, one part of the heavy distillate oil 4 is recycled to the atmospheric distillation column V2, and the other part can be sent to a coal tar processing plant for further separating products such as acenaphthene, dibenzofuran, industrial fluorene and the like.
The temperature of the top of the atmospheric distillation tower V2 is 210-225 ℃, the temperature of the side line is 235-260 ℃, and the temperature of the bottom of the atmospheric distillation tower is 290-310 ℃.
(2) Azeotropic distillation of methylnaphthalene enriched fractions
Mixing the methylnaphthalene enriched fraction 3 obtained in the step (1) with an entrainer 10 according to a certain proportion, heating the mixture to a certain temperature, and then feeding the mixture into an azeotropic distillation tower V3 for azeotropic distillation. The azeotropic distillate 5 obtained from the top of the azeotropic distillation column V3 is fed into a separator to recycle the entrainer 10, the residual oil 6 is obtained from the bottom of the column, and the residual oil 6 is thrown out to be used as a raw material for extracting other fine chemicals.
(3) Recovery of entrainer
Because the entrainer 10 and the water 9 have strong intersolubility, the entrainer 10 is recovered by a water extraction method, and after the azeotropic distillate 5 obtained in the step (2) is mixed with the water 9, the mixture is firstly subjected to ultrasonic mixing in an ultrasonic static mixer V4 and then enters a separator V5 for oil-water standing separation. And separating a water phase and an oil phase from the separator, wherein the water phase is an entrainer mixture 7 comprising an entrainer 10 and water 9, and the oil phase is a crude product 8 of the 2-methylnaphthalene.
The water phase from the separator V5 enters a rectifying tower V6 for distillation separation of the entrainer 10 and the water 9, and the entrainer 10 obtained from the bottom of the tower after separation returns to the step (2) to be mixed with the methylnaphthalene enriched fraction 3 for recycling; and returning the water obtained from the top of the tower after separation to be mixed with the azeotropic distillate 5 for recycling. The crude 2-methylnaphthalene 8 from the separator V5 is purified by melting crystallization.
(4) Melt crystallization of methylnaphthalene crude product
The method adopts a mode that two intermittent melt crystallizers V8 are connected in parallel to alternately carry out the crystallization and purification of the 2-methylnaphthalene, thereby achieving the aim of continuous crystallization and purification. In the batch type melting crystallizer V8, the crude methylnaphthalene 8 undergoes the processes of crystal growth, sweating, melting and the like in the batch type melting crystallizer V8, and finally the purpose of crystallization and purification is achieved. The crude methylnaphthalene 8 is melted, crystallized and purified to obtain a high-purity 2-methylnaphthalene product 13, liquid discharged in the processes of crystal growth and sweating is residual mother liquor 12, and the residual mother liquor 12 can be used as a raw material for extracting 1-methylnaphthalene. The purity of the 2-methylnaphthalene product 13 obtained after crystallization and purification is 99.0-99.9%, and the product yield is 70% -90%.
In some specific embodiments, in the step (1), the atmospheric distillation tower V2 is a packed tower, the height of the packing is equivalent to a stainless steel packed tower with 30-50 layers of theoretical plates, a part of heavy distillate oil 4 at the bottom of the tower is recycled and mixed with wash oil and then enters the atmospheric distillation tower V2, a part of heavy distillate oil is thrown outwards, the proportion of the throwing outwards and the recycling is 2-5: 1, and the content of 2-methylnaphthalene in the obtained methylnaphthalene enriched fraction 3 is 50-70%.
In some embodiments, as shown in FIG. 2, the azeotropic distillation column V3 employs a concentric tube precision separation column, which is formed by fusing two precisely designed and precisely calibrated concentric tubes, and has spiral grooves 22 on the inner surface to enable efficient mass and heat transfer between the vertically rising vapor and the liquid film in the concentric annular gap, and is made of glass or stainless steel, and the theoretical plate number of the separation column is 80-120.
In some specific embodiments, as shown in fig. 3, the melt crystallizer is a full-filling cube type static crystallizer, the melt crystallizer is shaped like a cube, and is provided with a temperature control medium outlet 14, a temperature control medium inlet 15, a material inlet 16 and a material outlet 17, a plurality of groups of mutually parallel crystallization plates are arranged in the melt crystallizer, as shown in fig. 4, each group of crystallization plates is provided with a spiral protrusion 20, and a crystal layer grows on the protrusion 20 during crystallization and is not easy to fall off; in the sweating process, the crystal layer falls off from the growth surface of the crystal plate, enters the grooves 21 among the protrusions 20 and keeps in contact with the heat exchange surface, so that the problem that the crystal layer is easy to fall off in the sweating process is well solved; heating and condensing media (namely temperature control media) circulate inside the crystallization plates, the temperature control media flow in through a crystallization plate temperature control media inlet 18, flow out through a crystallization plate temperature control media outlet 19, circulate to the next group of crystallization plates, and finally flow out through a temperature control media outlet 14 of the melt crystallizer. The material of the crystallization plate is stainless steel, organic glass or other alloys.
In some specific embodiments, in step (2), the entrainer is a single compound entrainer or a mixture type entrainer, wherein the single compound entrainer is any one of ethylene glycol, diethylene glycol, ethanolamine, diethylene glycol, and N-methylformamide, and the mixture type entrainer is a mixture of heptane and ethanolamine or a mixture of heptane and ethylene glycol.
When a single compound entrainer is adopted, the mass ratio of the methyl naphthalene enriched distillate oil to the entrainer is 1-3: 1; when the mixture type entrainer is adopted, the mass ratio of heptane to ethanolamine or heptane to ethylene glycol in the mixture type entrainer is 0.2-1: 1, and the mass ratio of the methylnaphthalene-enriched distillate oil to the entrainer is 1: 0.8-2.
In some specific embodiments, in the step (2), the middle part of the azeotropic distillation tower V3 is fed, the temperature at the top of the tower is 150-175 ℃, the pressure at the top of the tower is 1-4 KPa, and the reflux ratio is 5-15; the temperature of the tower bottom is 220-245 ℃, and the pressure of the tower bottom is 10-15 KPa.
In some specific embodiments, in the step (3), the power of the ultrasonic static mixer is 5-10 kW, and the frequency is 20-40 KHz; the operating temperature of the separator is 50-80 ℃, the standing time is 0.2-1.0 hour, and the purity of the crude 2-methylnaphthalene obtained after separation is 80-95%.
In some specific embodiments, in the step (4), the initial temperature in the crystal growth process is 35-40 ℃, the cooling rate is 3-8 ℃/h, the final temperature is 8-12 ℃, preferably 10 ℃, and the constant temperature time is 0.5-1 h. The heating rate in the sweating process is 2-6 ℃/h, and the final temperature is 30-32 ℃. The heating rate in the melting process is 2-8 ℃/h, the final temperature is 45-50 ℃, and the final temperature constant-temperature time is 0.5-1 h.
In some specific embodiments, the number of parallel batch melt crystallizers is not limited to 2.
In some specific embodiments, each batch crystallizer V8 is connected to a digitally controlled temperature oil bath V7, which transports the heated cooling medium 11 between the digitally controlled temperature oil bath V7 and the batch crystallizer V8.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the present disclosure, the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" and the like mean that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A method for extracting high-purity 2-methylnaphthalene from wash oil is characterized by comprising the following steps:
s1, rectifying and separating the wash oil to obtain methylnaphthalene enriched fraction;
s2, introducing the methylnaphthalene enriched fraction into an azeotropic distillation tower for azeotropic distillation to obtain an azeotropic distillate;
s3, introducing the azeotropic distillate into a separator to obtain a crude product of 2-methylnaphthalene;
s4, introducing the crude 2-methylnaphthalene into a plurality of batch type melt crystallizers arranged in parallel to crystallize and purify the 2-methylnaphthalene.
2. The method of claim 1, wherein in the step S1, the wash oil is rectified and separated by an atmospheric distillation tower to obtain a naphthalene fraction light oil, a methylnaphthalene enriched fraction and a heavy distillate oil, wherein a part of the heavy distillate oil is recycled to the atmospheric distillation tower, and another part of the heavy distillate oil is recycled.
3. The method as claimed in claim 1, wherein in step S2, the methylnaphthalene-rich fraction and the entrainer are mixed in proportion, and the mixture is heated to a certain temperature and then enters an azeotropic distillation tower for azeotropic distillation.
4. The method according to claim 3, wherein the entrainer is a single compound entrainer or a mixture type entrainer, wherein the single compound entrainer is any one of ethylene glycol, diethylene glycol, ethanolamine, diethylene glycol and N-methylformamide, and the mixture type entrainer is a mixture of heptane and ethanolamine or a mixture of heptane and ethylene glycol;
when a single compound entrainer is adopted, the mass ratio of the methyl naphthalene enriched distillate oil to the entrainer is 1-3: 1; when the mixture type entrainer is adopted, the mass ratio of heptane to ethanolamine or heptane to ethylene glycol in the mixture type entrainer is 0.2-1: 1, and the mass ratio of the methylnaphthalene-enriched distillate oil to the entrainer is 1: 0.8-2.
5. The method according to claim 3, wherein in step S3, the azeotropic distillate and water are passed into an ultrasonic static mixer for ultrasonic mixing, and then passed into a separator for standing separation of oil and water, and an aqueous phase and an oil phase are separated from the separator,
wherein the water phase is an entrainer and water, the water phase enters a rectifying tower for distillation separation of the entrainer and the water, and the separated entrainer is returned to the step S2 to be mixed with the methylnaphthalene enriched fraction for recycling; the separated water is returned to be mixed with the azeotropic distillate for recycling;
and the oil phase is a crude product of 2-methylnaphthalene, and the oil phase enters an intermittent melt crystallizer to carry out crystallization and purification on the 2-methylnaphthalene.
6. The method of claim 1, wherein in step S4, there are 2 batch melt crystallizers.
7. The method of claim 2, wherein the naphthalene fraction light oil is obtained from the top of an atmospheric distillation tower, the methylnaphthalene enriched fraction is obtained from the side line of the atmospheric distillation tower, the heavy distillate oil is obtained from the bottom of the atmospheric distillation tower, the temperature of the top of the tower is 210-225 ℃, the temperature of the side line is 235-260 ℃, and the temperature of the bottom of the tower is 290-310 ℃.
8. The method according to claim 3, wherein the overhead temperature of the azeotropic distillation tower is 150-175 ℃, the overhead pressure is 1-4 KPa, and the reflux ratio is 5-15; the temperature of the tower bottom is 220-245 ℃, and the pressure of the tower bottom is 10-15 KPa.
9. The method according to any one of claims 1 to 8, wherein in the step S4, the initial temperature in the crystal growth process is 35 to 40 ℃, the temperature reduction rate is 3 to 8 ℃/h, the final temperature is 8 to 12 ℃, and the constant temperature time is 0.5 to 1 h;
the heating rate in the sweating process is 2-6 ℃/h, and the final temperature is 30-32 ℃;
the heating rate in the melting process is 2-8 ℃/h, the final temperature is 45-50 ℃, and the final temperature constant-temperature time is 0.5-1 h.
10. The method according to claim 5, wherein the operating temperature of the separator is 50 to 80 ℃ and the standing time is 0.2 to 1 hour.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
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| CN202210135569.3A CN114394880A (en) | 2022-02-14 | 2022-02-14 | Method for extracting high-purity 2-methylnaphthalene from wash oil |
| PCT/CN2022/115478 WO2023040641A1 (en) | 2021-09-14 | 2022-08-29 | Acylation solution and process method for continuously synthesizing acyl naphthalene using acylation solution |
| JP2022573236A JP2023546762A (en) | 2021-09-14 | 2022-08-29 | Acylation liquid and process method for continuous synthesis of acylnaphthalene using acylation liquid |
| US18/057,394 US20230095165A1 (en) | 2021-09-14 | 2022-11-21 | Method for continuous synthesis of acylnaphthalene with acylation liquid |
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