CN116354784A - Process for separating beta-methylnaphthalene and alpha-methylnaphthalene by mixed methylnaphthalene - Google Patents
Process for separating beta-methylnaphthalene and alpha-methylnaphthalene by mixed methylnaphthalene Download PDFInfo
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- QPUYECUOLPXSFR-UHFFFAOYSA-N 1-methylnaphthalene Chemical compound C1=CC=C2C(C)=CC=CC2=C1 QPUYECUOLPXSFR-UHFFFAOYSA-N 0.000 title claims abstract description 136
- QIMMUPPBPVKWKM-UHFFFAOYSA-N 2-methylnaphthalene Chemical compound C1=CC=CC2=CC(C)=CC=C21 QIMMUPPBPVKWKM-UHFFFAOYSA-N 0.000 title claims abstract description 90
- 238000000034 method Methods 0.000 title claims abstract description 48
- 230000008569 process Effects 0.000 title claims abstract description 36
- 239000002994 raw material Substances 0.000 claims abstract description 22
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims abstract description 15
- 239000005977 Ethylene Substances 0.000 claims abstract description 15
- 238000000998 batch distillation Methods 0.000 claims abstract description 4
- 238000010992 reflux Methods 0.000 claims description 20
- 238000012856 packing Methods 0.000 claims description 17
- 239000000945 filler Substances 0.000 claims description 10
- 239000000463 material Substances 0.000 claims description 9
- DZTYCPNBSJZKSS-UHFFFAOYSA-N 1,3-dimethyl-1h-indene Chemical compound C1=CC=C2C(C)C=C(C)C2=C1 DZTYCPNBSJZKSS-UHFFFAOYSA-N 0.000 claims description 8
- 229910000975 Carbon steel Inorganic materials 0.000 claims description 7
- 239000010962 carbon steel Substances 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 7
- 239000010410 layer Substances 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 239000002356 single layer Substances 0.000 claims description 5
- 238000010923 batch production Methods 0.000 claims description 4
- 238000009835 boiling Methods 0.000 claims description 4
- 150000003839 salts Chemical class 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims 1
- 230000008901 benefit Effects 0.000 abstract description 6
- 238000005292 vacuum distillation Methods 0.000 abstract 1
- 239000000047 product Substances 0.000 description 27
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 description 14
- ZUOUZKKEUPVFJK-UHFFFAOYSA-N diphenyl Chemical compound C1=CC=CC=C1C1=CC=CC=C1 ZUOUZKKEUPVFJK-UHFFFAOYSA-N 0.000 description 10
- 239000011269 tar Substances 0.000 description 9
- 239000000203 mixture Substances 0.000 description 8
- SIKJAQJRHWYJAI-UHFFFAOYSA-N Indole Chemical compound C1=CC=C2NC=CC2=C1 SIKJAQJRHWYJAI-UHFFFAOYSA-N 0.000 description 6
- ZMXIYERNXPIYFR-UHFFFAOYSA-N 1-ethylnaphthalene Chemical compound C1=CC=C2C(CC)=CC=CC2=C1 ZMXIYERNXPIYFR-UHFFFAOYSA-N 0.000 description 5
- BSHJHVHMLRKHBZ-UHFFFAOYSA-N 2-ethyl-1h-indene Chemical compound C1=CC=C2CC(CC)=CC2=C1 BSHJHVHMLRKHBZ-UHFFFAOYSA-N 0.000 description 5
- 235000010290 biphenyl Nutrition 0.000 description 5
- 239000004305 biphenyl Substances 0.000 description 5
- 238000004821 distillation Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 239000012808 vapor phase Substances 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- PZOUSPYUWWUPPK-UHFFFAOYSA-N indole Natural products CC1=CC=CC2=C1C=CN2 PZOUSPYUWWUPPK-UHFFFAOYSA-N 0.000 description 3
- RKJUIXBNRJVNHR-UHFFFAOYSA-N indolenine Natural products C1=CC=C2CC=NC2=C1 RKJUIXBNRJVNHR-UHFFFAOYSA-N 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- QNLZIZAQLLYXTC-UHFFFAOYSA-N 1,2-dimethylnaphthalene Chemical compound C1=CC=CC2=C(C)C(C)=CC=C21 QNLZIZAQLLYXTC-UHFFFAOYSA-N 0.000 description 2
- YBYIRNPNPLQARY-UHFFFAOYSA-N 1H-indene Chemical compound C1=CC=C2CC=CC2=C1 YBYIRNPNPLQARY-UHFFFAOYSA-N 0.000 description 2
- MWPLVEDNUUSJAV-UHFFFAOYSA-N anthracene Chemical compound C1=CC=CC2=CC3=CC=CC=C3C=C21 MWPLVEDNUUSJAV-UHFFFAOYSA-N 0.000 description 2
- 238000010533 azeotropic distillation Methods 0.000 description 2
- 239000000084 colloidal system Substances 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 150000002475 indoles Chemical class 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- YNPNZTXNASCQKK-UHFFFAOYSA-N phenanthrene Chemical compound C1=CC=C2C3=CC=CC=C3C=CC2=C1 YNPNZTXNASCQKK-UHFFFAOYSA-N 0.000 description 2
- FZTYGIKSBFTSNW-UHFFFAOYSA-N 1-methylnaphthalene Chemical compound CC1=CC=CC2=CC=CC=C12.CC1=CC=CC2=CC=CC=C12 FZTYGIKSBFTSNW-UHFFFAOYSA-N 0.000 description 1
- HLMGIACBRPHDBD-UHFFFAOYSA-N CC1=CC2=CC=CC=C2C=C1.CC1=CC2=CC=CC=C2C=C1 Chemical compound CC1=CC2=CC=CC=C2C=C1.CC1=CC2=CC=CC=C2C=C1 HLMGIACBRPHDBD-UHFFFAOYSA-N 0.000 description 1
- CWRYPZZKDGJXCA-UHFFFAOYSA-N acenaphthene Chemical compound C1=CC(CC2)=C3C2=CC=CC3=C1 CWRYPZZKDGJXCA-UHFFFAOYSA-N 0.000 description 1
- 238000003556 assay Methods 0.000 description 1
- 125000002619 bicyclic group Chemical group 0.000 description 1
- 239000011280 coal tar Substances 0.000 description 1
- 239000007859 condensation product Substances 0.000 description 1
- 238000001944 continuous distillation Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 125000002950 monocyclic group Chemical group 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 125000005575 polycyclic aromatic hydrocarbon group Chemical group 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000004230 steam cracking Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000002351 wastewater Substances 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Organic Chemistry (AREA)
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- Oil, Petroleum & Natural Gas (AREA)
- Water Supply & Treatment (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a process for separating beta-methylnaphthalene and alpha-methylnaphthalene from mixed methylnaphthalene, which takes mixed methylnaphthalene products produced by a mixed methylnaphthalene tower of an ethylene tar comprehensive utilization process as raw materials, and separates the beta-methylnaphthalene and the alpha-methylnaphthalene through an intermittent rectification process. Wherein, the batch distillation adopts vacuum distillation under reduced pressure, and is carried out in four stages to respectively obtain beta-methylnaphthalene and alpha-methylnaphthalene meeting the purity requirement. The invention has the advantages of high product purity, high yield, simple process, low operation requirement, high automation degree and the like.
Description
Technical Field
The invention relates to the field of mixed methylnaphthalene separation, in particular to a process for separating beta-methylnaphthalene and alpha-methylnaphthalene by using mixed methylnaphthalene.
Background
Ethylene tar is a high-temperature condensation product of raw materials and products of ethylene cracking raw materials in a steam cracking process, and has extremely complex composition, mainly comprising monocyclic, bicyclic and polycyclic aromatic hydrocarbons. The yield of ethylene tar varies depending on the cracking raw material, and generally is about 10% to 15% (w) of the ethylene raw material, and the yield increases with the increase in weight of the ethylene raw material. The yield of each fraction of ethylene tar between 205 and 300 ℃ is higher, approximately 40 to 60 percent, and the rest is heavier colloid asphaltene component. The main components of the fraction with the Initial Boiling Point (IBP) to 205 ℃ are indene and homologs thereof, the fraction with the temperature of 205 to 225 ℃ is naphthalene, the fraction with the temperature of 225 to 245 ℃ is mainly methylnaphthalene, the fraction with the temperature of 245 to 300 ℃ is mainly dimethylnaphthalene, the fraction with the temperature of 300 to 360 ℃ contains a large amount of anthracene, acenaphthene, phenanthrene and the like, and the substances with the temperature above 360 ℃ are colloid and asphaltene with high carbon-hydrogen ratio.
The market price of the beta-methylnaphthalene and the alpha-methylnaphthalene is 25000-30000 yuan/ton, the price of the mixed methylnaphthalene is 4800-6300 yuan/ton, the ethylene tar contains rich mixed methylnaphthalene, and if the beta-methylnaphthalene and the alpha-methylnaphthalene in the mixed methylnaphthalene are separated, the purity is improved, and the economic benefit is quite remarkable. However, ethylene tar mixed methylnaphthalene has a large amount of impurities, mainly naphthalene, 2-ethyl-1H-indene, 1, 3-dimethyl-1H-indene, indole, biphenyl, 1-ethylnaphthalene and the like, and the boiling points of beta-methylnaphthalene and alpha-methylnaphthalene are very close, only differ by about 3 ℃, and the separation by common continuous rectification is very difficult and the investment cost is very high.
At present, mixed methylnaphthalenes have been reported in the prior art, such as CN209537346U, CN203244800U, CN111960912A, CN1059657C, CN 100506762C.
The beta-methylnaphthalene separation technology described in the above patent is mostly formed by combining coal tar purification through azeotropic distillation, crystallization and other processes, and has the advantages of large investment and high energy consumption.
Disclosure of Invention
The invention aims to: aiming at the defects of complex technology, large investment, high energy consumption and the like of the existing continuous azeotropic distillation technology or continuous distillation and crystallization technology for separating mixed methylnaphthalene, the process for separating beta-methylnaphthalene and alpha-methylnaphthalene is provided, and has the advantages of simple process, low equipment investment, safe operation, high product purity, high product yield and the like, the purity of the obtained beta-methylnaphthalene is more than 95% (wt), and the purity of the alpha-methylnaphthalene is more than 92% (wt).
To achieve the above object, the present application proposes a process for separating β -methylnaphthalene and α -methylnaphthalene by mixing methylnaphthalene: the ethylene tar comprehensive utilization process mixes the raw materials from the methylnaphthalene tower, and the main components are as follows: naphthalene, 2-ethyl-1H-indene, 1, 3-dimethyl-1H-indene, beta-methylnaphthalene, alpha-methylnaphthalene, indole, biphenyl, 1-ethylnaphthalene and the like are subjected to fixed reflux ratio type batch rectification by the following steps, wherein the reflux ratio is always kept between 15 and 40:
(1) Introducing a mixed methylnaphthalene raw material obtained from an ethylene tar comprehensive utilization process into a tower kettle of a batch rectifying tower (T1), wherein 4 receivers are arranged at the top of the tower to respectively receive different tower top distillate products;
(2) Setting the temperature of a tower kettle to 182-183 ℃ and the temperature of a tower top to 147-166 ℃ through reduced pressure batch distillation, and firstly, enabling residual oil with the atmospheric boiling point of 218-230 ℃ produced by the tower top to enter a receiver 1 (V1);
(3) When the mass fraction of 1, 3-dimethyl-1H-indene in the product of the receiver 1 (V1) is 45-55%, switching the tower top distillate to the receiver 2 (V2), stopping feeding of the receiver 1 (V1), setting the tower bottom temperature at 183-188 ℃, setting the tower top temperature at 166-168 ℃, collecting the distillate to the receiver 2 (V2), and obtaining beta-methylnaphthalene with the purity of more than 95wt% in the receiver 2 (V2);
(4) When the mass fraction of the beta-methylnaphthalene in the receiver 2 (V2) reaches 95-98%, the tower top distillate is switched to the receiver 3, the feeding of the receiver 2 (V2) is stopped, and 30-50% (wt) of beta-methylnaphthalene is obtained in the receiver 3; setting the temperature of the tower kettle at 188-189 ℃, setting the temperature of the tower top at 168-169 ℃, and collecting distillate to enter a receiver 3 (V3);
(5) Stopping feeding of the receiver 3 (V3) and converting the feeding into the receiver 4 (V4) when the purity of the beta-methylnaphthalene in the receiver 3 (V3) is 30-50wt%;
(6) Setting the temperature of the tower kettle to 189-193 ℃, setting the temperature of the tower top to 169-171 ℃, collecting distillate, entering a receiver 4 (V4), and stopping distillation when the mass fraction of alpha-methylnaphthalene in the receiver 4 (V4) reaches 92-96%;
(7) The tower bottom raffinate, the receiver 1 (V1) raffinate, the receiver 2 (V2) beta-methylnaphthalene product, the receiver 3 (V3) mixed methylnaphthalene product and the receiver 4 (V4) alpha-methylnaphthalene product are pumped out of the device through pumps respectively, and the operation of one intermittent flow is finished.
Preferably, in the step (1), the raw material feeding temperature is 160-180 ℃, and the feeding time is controlled within 1 hour; the volume of the tower kettle is 1.2-2 times of the volume of the primary feeding. The saturation temperature of the feeding temperature can save energy; the feeding time is controlled within 1 hour, so that the operation time of the whole process can be shortened, energy is saved, and enough treatment time is reserved for special conditions in the production process; the volume of the tower kettle is selected to be too large, and the investment cost is higher, so that the volume of the tower kettle is designed to be 1.2-2 times of the feeding volume according to the standard requirement, and the normal production requirement is met.
The batch rectifying tower (T1) is a packed tower, the selected packing is any one of new generation regular packing Mellapak PLUS202Y, 252Y, 352Y, 452Y, 602Y and 752Y, and the packing material is metal 304 or 316L material; the number of the filler layers is 5-8, and the height of a single-layer filler is 4-6m; the total tower height is between 30 and 50m, the tower diameter is between 1 and 3m, and the tower plate number is between 80 and 120.
Wherein, the tower kettle adopts a forced circulation heating method, and a forced circulation pump and a reboiler of the tower kettle are arranged. Wherein the forced circulation pump of the tower kettle is a centrifugal pump, the reboiler adopts a kettle type reboiler or a shell-and-tube heat exchanger, and the pump and the reboiler are made of carbon steel, 304 or 316L; the heating medium is steam, heat conducting oil or molten salt.
The pressure at the top of the batch rectifying tower (T1) is controlled to be 5-20KPA absolute pressure by a vacuum pump.
Preferably, the tower top vacuum degree is provided by a vacuum pump, the vacuum pump adopts a water ring type vacuum pump, a screw vacuum pump or a Roots vacuum pump, and the vacuum pump is made of 304L or 316L.
The pressure drop of the batch rectifying tower (T1) is between 5 and 10KPA, and the flooding factor in the tower is controlled between 40 and 85 percent.
Preferably, the batch rectification is operated by adopting a fixed reflux ratio method, and the fixed reflux ratio is set to be 30-33. Through the operation of the immobilized reflux ratio, the operation is simple, and meanwhile, the energy is saved.
Preferably, the four receivers are made of carbon steel, 304 or 316L.
By using the process method provided by the invention, the time of one batch process is 8-12 hours, and the total time of one batch process is equal to the feeding time, the distillation time, the discharging time and the idle time. The mass fraction of beta-methylnaphthalene in the receiver 2 (V2) is 95-98%, and the mass fraction of V2 alpha-methylnaphthalene in the receiver 4 (V4) is 92-96%.
In the step (1), the raw material feeding temperature is 160-180 ℃, the feeding time is controlled within 1 hour, and the volume of the tower kettle is 1.2-2 times of the volume of one-time feeding. The 4 receivers are arranged at the top of the column to receive different overhead products respectively.
The batch rectifying tower is a packed tower, the selected packing is one of new generation regular packing Mellapak PLUS202Y\252Y\352 Y\602Y\752Y, and the packing material is metal 304 or 316L material. The number of the filler layers is 5-8, and the height of the single-layer filler is 4-6m. The total tower height is between 30 and 50m. The diameter of the tower is between 1 and 3 m.
The tower kettle adopts a forced circulation heating method, and a forced circulation pump and a reboiler of the tower kettle are arranged. The forced circulation pump of the tower kettle is a centrifugal pump, the reboiler adopts a kettle type reboiler or a shell-and-tube heat exchanger, and the pump and the reboiler are made of carbon steel, 304 or 316L. The heating medium is steam, heat conducting oil or molten salt.
The batch rectifying tower T1 is a reduced pressure rectifying tower, and the pressure at the top of the tower is controlled at 5-20KPA absolute pressure. The temperature of the tower top is controlled between 140 and 180 ℃, and the temperature of the tower bottom is controlled between 180 and 200 ℃.
The pressure drop of the packed tower is controlled between 5 KPA and 10KPA, the flooding factor in the tower is controlled between 40% and 85%, the reflux ratio is controlled between 15% and 40%, and the number of tower plates is controlled between 80% and 120.
Compared with the prior art, the invention has the following advantages:
(1) The purity of the beta-methylnaphthalene product is high, the yield is high, the purity of the beta-methylnaphthalene product can reach more than 95%, and the yield is more than 85%;
(2) The purity of the alpha-methylnaphthalene product is high, the yield is high, the purity of the alpha-methylnaphthalene product can reach more than 92%, and the yield is more than 80%;
(3) The process is simple, the operation requirement is low, the automation degree is high, the process flow is simple, no entrainer is added, a crystallization device is not needed, the whole device is depressurized, the operation is simple and safe, and the energy consumption is low;
(4) The investment cost is low, the process is operated under reduced pressure, the equipment is not excessively high in requirement, and the cost and the equipment investment are reduced;
(5) The method is energy-saving and environment-friendly, the whole process has no wastewater and waste solids discharge, and only a small amount of waste gas is discharged into an environment-friendly system.
Drawings
FIG. 1 is a schematic diagram of a process and flow diagram for separating mixed methylnaphthalenes;
wherein: t1-batch rectifying tower, P1-forced circulation pump, P2-tower kettle discharge pump, P3-receiver 1 discharge pump, P4-receiver 2 discharge pump, P5-receiver 3 discharge pump, P6-receiver 4 discharge pump, P7-vacuum pump, E1-reboiler, E2-condenser 1, E3-condenser 2, V1-receiver 1, V2-receiver 2, V3-receiver 3, V4-receiver 4.
Detailed Description
The foregoing and/or other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings and detailed description.
In the following examples, the beta-methylnaphthalene standard was implemented according to the industry standard YB/T4150-2018, "beta-methylnaphthalene". The mass fraction of the beta-methylnaphthalene is not less than 95%, and the mass fraction of the alpha-methylnaphthalene is not less than 90%, which is confirmed by an experimental assay.
As shown in fig. 1, the application provides a process flow for separating beta-methylnaphthalene and alpha-methylnaphthalene by mixing methylnaphthalene, and the whole device comprises a batch rectifying tower T1, wherein the batch rectifying tower T1 is a packed tower, and the packing can be any one of new generation structured packing Melapak PLUS202Y, 252Y, 352Y, 452Y, 602Y and 752Y. The tower kettle is provided with a tower kettle forced circulation pump and a reboiler, the tower kettle forced circulation pump is a centrifugal pump, the reboiler adopts a kettle type reboiler or a shell-and-tube heat exchanger, and the pump and the reboiler are made of carbon steel, 304 or 316L; the heating medium is steam, heat conducting oil or molten salt.
The 4 receivers at the top of the column receive different overhead products, respectively receiver 1V1, receiver 2V2, receiver 3V3 and receiver 4V4. The E2 condenser is used for condensing vapor phase products from the top of the rectifying tower to change the vapor phase products from the top of the rectifying tower into liquid, one part of the vapor phase products flow back into the tower, and the other part of vapor phase products flow back to the receiver; e3 condenser is used for condensing the product carried by the vacuum pump, preventing the product loss and improving the product yield.
The ethylene tar comprehensive utilization process mixes the raw materials from the methylnaphthalene tower, and the main components are as follows: naphthalene, 2-ethyl-1H-indene, 1, 3-dimethyl-1H-indene, beta-methylnaphthalene, alpha-methylnaphthalene, indole, biphenyl, 1-ethylnaphthalene, and the like. Batch rectification was performed by the following steps:
the first step: setting reflux ratio at 15-40, tower bottom temperature at 182-183 deg.c and tower top temperature at 147-166 deg.c, eliminating light phase impurity, and feeding light phase impurity into the receiver 1V1. When the mass fraction of 1, 3-dimethyl-1H-indene in receiver 1V1 was set to 45-55%, the overhead was switched to receiver 2V2.
And a second step of: setting reflux ratio as 15-40, tower bottom temperature 183-188 deg.c, tower top temperature 166-168 deg.c, collecting beta-methylnaphthalene, and feeding beta-methylnaphthalene into receiver 2V2. The purity of the beta-methylnaphthalene in the receiver 2V2 is between 95 and 98 percent (wt), and the yield is between 60 and 80 percent. When the mass fraction of beta-methylnaphthalene in the receiver 2V2 was set to 95-98%, the overhead was switched to the receiver 3V3.
And a third step of: setting reflux ratio at 15-40, tower bottom temperature at 188-189 deg.c, tower top temperature at 168-169 deg.c, collecting beta-methylnaphthalene affecting alpha-methylnaphthalene purity, and entering into receiver 3V3. When the purity of beta-methylnaphthalene in receiver 3V3 was set at 30-50% (wt), the overhead was switched to receiver 4V4.
Fourth step: setting reflux ratio at 15-40, tower bottom temperature at 189-193 deg.c and tower top temperature at 169-171 deg.c, collecting alpha-methylnaphthalene, and feeding alpha-methylnaphthalene into receiver 4V4. The purity of the alpha-methylnaphthalene in the receiver 4V4 is 92-96% (wt), and the yield is 50-80%. When the mass fraction of alpha-methylnaphthalene in the receiver 4V4 was set to 92-96%, distillation was stopped.
Through process optimization, batch rectification is operated by adopting a fixed reflux ratio method, the reflux ratio is optimized to be 15-40 at the minimum, the operation is simple, and the energy is saved.
The tower residue, the receiver 1V1 residue, the receiver 2V2 beta-methylnaphthalene product, the receiver 3V3 mixed methylnaphthalene and the receiver 4V4 alpha-methylnaphthalene product are pumped out of the device through pumps (P2-6). And (5) finishing the operation of one intermittent flow.
The batch rectifying tower T1 is a reduced pressure rectifying tower, and the pressure at the top of the tower is controlled at 5-20KPA absolute pressure. The temperature of the tower top is controlled between 140 and 180 ℃, and the temperature of the tower bottom is controlled between 180 and 200 ℃.
The pressure drop of the packed tower is controlled between 5 KPA and 10KPA, the flooding factor in the tower is controlled between 40% and 85%, the reflux ratio is controlled between 15% and 40%, and the number of tower plates is controlled between 80% and 120.
The vacuum degree of the tower top is provided by a vacuum pump P7, the vacuum pump adopts a water ring type vacuum pump, a screw vacuum pump or a Roots vacuum pump, and the vacuum pump is made of 304L or 316L.
The material of the receiver 1-4 is carbon steel, 304 or 316L. The primary rectifying time is between 8 and 12 hours.
In the following embodiments, the apparatus and the process steps are all implemented.
Example 1
The mixed methylnaphthalene raw material in the embodiment is from the top oil extracted from the mixed methylnaphthalene tower of the ethylene tar comprehensive utilization process. The raw materials are fed into a large tank at a mass flow rate of 650kg/h at 160 ℃ and a pressure of 500Kpa, and then fed into a batch rectifying tower at one time by a large pump with a mass flow rate of more than or equal to 5200kg/h for batch rectifying. The composition of the raw material mixed methylnaphthalene is shown in table 1. The batch rectifying tower adopts a packed tower, wherein the selected packing is a new generation of regular packing Mellapak PLUS 352Y, and the packing material is metal 304. The number of filler layers is 7, and the height of a single-layer filler is 4.9m. The total tower height was 50m. The diameter of the tower is 1m, the fixed reflux ratio is 33, the once feeding amount of the tower kettle is 5200kg, and the distillation time is 4.5h. Finally, the beta-methylnaphthalene product with the purity of 1870t/a being 98% (wt) and the alpha-methylnaphthalene product with the purity of 1370t/a being 93% (wt) are obtained, the yield of the beta-methylnaphthalene is 85%, and the yield of the alpha-methylnaphthalene is 75%. The raw material is 650kg/h, 8000 h=5200 t/a, and the annual yield is 5074 ten thousand yuan.
TABLE 1
| Sequence number | Composition of the composition | Unit (B) | Numerical value |
| 1 | Naphthalene (naphthalene) | wt％ | 0.008 |
| 2 | 2-ethyl-1H-indene | wt％ | 0.026 |
| 3 | 1, 3-dimethyl-1H-indene | wt％ | 0.0586 |
| 4 | 2-methylnaphthalene (beta-methylnaphthalene) | wt％ | 0.4239 |
| 5 | 1-methylnaphthalene (alpha-methylnaphthalene) | wt％ | 0.3258 |
| 6 | Indole compounds | wt％ | 0.0186 |
| 7 | Biphenyl | wt％ | 0.0553 |
| 8 | 1-ethyl naphthalene | wt％ | 0.0838 |
Example 2
The apparatus and procedure of this example were the same as in example 1, except that the flow rate and the component content of the raw material mixed methylnaphthalene were different, and the composition is shown in Table 2.
TABLE 2
| Sequence number | Composition of the composition | Unit (B) | Numerical value |
| 1 | Naphthalene (naphthalene) | wt％ | 0.01 |
| 2 | 2-ethyl-1H-indene | wt％ | 0.03 |
| 3 | 1, 3-dimethyl-1H-indene | wt％ | 0.0623 |
| 4 | 2-methylnaphthalene | wt％ | 0.4126 |
| 5 | 1-methylnaphthalene | wt％ | 0.2974 |
| 6 | Indole compounds | wt％ | 0.0196 |
| 7 | Biphenyl | wt％ | 0.0836 |
| 8 | 1-ethyl naphthalene | wt％ | 0.0845 |
The raw material temperature is 180 ℃, the pressure is 500Kpa A, the mass flow is 1300kg/h, and the composition of the raw material mixed methylnaphthalene is shown in Table 1. The batch rectifying tower adopts a packed tower, wherein the selected packing is a new generation of regular packing Mellapak PLUS 452Y, and the packing material is metal 304. The number of the filler layers is 6, and the height of a single-layer filler is 5m. The total tower height was 45m. The diameter of the tower is 2m, the reflux ratio is 31, the primary feeding amount of the tower kettle is 10400kg, and the distillation time is 8.9h. Finally, the beta-methylnaphthalene product with the purity of 3730t/a being 95% (wt) and the alpha-methylnaphthalene product with the purity of 2500t/a being 92% (wt) are obtained, the yield of the beta-methylnaphthalene is 87%, and the yield of the alpha-methylnaphthalene is 81%. The raw material is 1300kg/h 8000 h=10400 t/a, and annual yield is 9638 ten thousand yuan.
The present invention provides a method and a method for separating mixed methylnaphthalene to prepare beta-methylnaphthalene and alpha-methylnaphthalene, the above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and the improvements and modifications should also be considered as the protection scope of the present invention. The components not explicitly described in this embodiment can be implemented by using the prior art.
Claims (10)
1. A process for separating beta-methylnaphthalene and alpha-methylnaphthalene from mixed methylnaphthalene is characterized in that mixed methylnaphthalene obtained by an ethylene tar comprehensive utilization process is used as a raw material, and fixed reflux ratio type batch rectification is carried out by the following steps that the reflux ratio is always kept between 15 and 40:
(1) Introducing a mixed methylnaphthalene raw material obtained from an ethylene tar comprehensive utilization process into a tower kettle of a batch rectifying tower (T1), wherein 4 receivers are arranged at the top of the tower to respectively receive different tower top distillate products;
(2) Setting reflux ratio at 15-40 by vacuum batch distillation, wherein the temperature of a tower bottom is 182-183 ℃, the temperature of a tower top is 147-166 ℃, and firstly, residual oil with atmospheric boiling point of 218-230 ℃ is produced at the tower top and enters a receiver 1 (V1);
(3) When the mass fraction of 1, 3-dimethyl-1H-indene in the product of the receiver 1 (V1) is 45-55%, switching the distillate at the top of the tower to the receiver 2 (V2), stopping feeding the receiver 1 (V1), setting the temperature of the tower kettle to 183-188 ℃, setting the temperature of the tower top to 166-168 ℃, and collecting the distillate to enter the receiver 2 (V2);
(4) When the mass fraction of the beta-methylnaphthalene in the receiver 2 (V2) is 95-98%, switching the tower top distillate to the receiver 3, stopping feeding of the receiver 2 (V2), setting the tower bottom temperature to 188-189 ℃, setting the tower top temperature to 168-169 ℃, and collecting the distillate to enter the receiver 3 (V3);
(5) Stopping feeding the receiver 3 (V3) to change into feeding the receiver 4 (V4) when the purity of the beta-methylnaphthalene in the receiver 3 (V3) is 30-50 wt%;
(6) Setting the temperature of the tower kettle to 189-193 ℃, setting the temperature of the tower top to 169-171 ℃, collecting distillate, entering a receiver 4 (V4), and stopping distilling when the mass fraction of alpha-methylnaphthalene in the receiver 4 (V4) reaches 92-96%;
(7) The tower residue, the residue in the receiver 1 (V1), the beta-methylnaphthalene product in the receiver 2 (V2), the mixed methylnaphthalene product in the receiver 3 (V3) and the alpha-methylnaphthalene product in the receiver 4 (V4) are pumped out of the device respectively through pumps, and the operation of one batch process is completed.
2. The process according to claim 1, wherein in the step (1), the raw material feeding temperature is 160-180 ℃, the feeding time is controlled within 1 hour, and the volume of the tower kettle is 1.2-2 times of the feeding volume of one time.
3. The process according to claim 1, wherein the batch rectifying column (T1) is a packed column, the selected packing is any one of new generation regulated packing melapak PLUS202Y, 252Y, 352Y, 452Y, 602Y and 752Y, and the packing material is metal 304 or 316L material; the number of the filler layers is 5-8, and the height of a single-layer filler is 4-6m; the total tower height is between 30 and 50m, the tower diameter is between 1 and 3m, and the tower plate number is between 80 and 120.
4. The process according to claim 1, wherein the tower kettle adopts a forced circulation heating method, and a tower kettle forced circulation pump and a reboiler are arranged. Wherein the forced circulation pump of the tower kettle is a centrifugal pump, the reboiler adopts a kettle type reboiler or a shell-and-tube heat exchanger, and the pump and the reboiler are made of carbon steel, 304 or 316L; the heating medium is steam, heat conducting oil or molten salt.
5. Process according to claim 1, characterized in that the overhead pressure of the batch column (T1) is controlled by a vacuum pump at an absolute pressure of 5-20KPA.
6. The process of claim/5, wherein the overhead vacuum is provided by a vacuum pump, the vacuum pump being a water ring vacuum pump, a screw vacuum pump, or a Roots vacuum pump, the vacuum pump being 304 or 316L.
7. Process according to claim 1, characterized in that the pressure drop in the batch column (T1) is between 5 and 10KPA, and the in-column flooding factor is controlled between 40 and 85%.
8. The process of claim 1 wherein the batch distillation is operated by a fixed reflux ratio method, the fixed reflux ratio being set to 30-33.
9. The process of claim 1, wherein the four receivers are made of carbon steel, 304 or 316L.
10. The process according to claim 1, wherein a batch process time is between 8 and 12 hours, the mass fraction of β -methylnaphthalene in receiver 2 (V2) is between 95 and 98% and the mass fraction of α -methylnaphthalene in receiver 4 (V4) is between 92 and 96%.
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