CN109761940B - Continuous rectifying device and process method for crude maleic anhydride - Google Patents
Continuous rectifying device and process method for crude maleic anhydride Download PDFInfo
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- CN109761940B CN109761940B CN201910203343.0A CN201910203343A CN109761940B CN 109761940 B CN109761940 B CN 109761940B CN 201910203343 A CN201910203343 A CN 201910203343A CN 109761940 B CN109761940 B CN 109761940B
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- maleic anhydride
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- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 title claims abstract description 93
- 238000000034 method Methods 0.000 title claims abstract description 47
- 230000008569 process Effects 0.000 title claims abstract description 27
- 238000007670 refining Methods 0.000 claims abstract description 124
- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 claims abstract description 95
- 238000010992 reflux Methods 0.000 claims abstract description 81
- 239000007788 liquid Substances 0.000 claims abstract description 65
- 235000019260 propionic acid Nutrition 0.000 claims abstract description 46
- IUVKMZGDUIUOCP-BTNSXGMBSA-N quinbolone Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H]([C@]4(C=CC(=O)C=C4CC3)C)CC[C@@]21C)C1=CCCC1 IUVKMZGDUIUOCP-BTNSXGMBSA-N 0.000 claims abstract description 46
- 238000005984 hydrogenation reaction Methods 0.000 claims abstract description 43
- 238000005406 washing Methods 0.000 claims abstract description 36
- 238000004458 analytical method Methods 0.000 claims abstract description 29
- 238000000926 separation method Methods 0.000 claims abstract description 24
- 238000010521 absorption reaction Methods 0.000 claims abstract description 22
- 238000004519 manufacturing process Methods 0.000 claims abstract description 10
- 239000007789 gas Substances 0.000 claims description 99
- 238000012856 packing Methods 0.000 claims description 66
- 239000000203 mixture Substances 0.000 claims description 61
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 44
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 43
- 239000001257 hydrogen Substances 0.000 claims description 38
- 229910052739 hydrogen Inorganic materials 0.000 claims description 38
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 35
- 239000003054 catalyst Substances 0.000 claims description 33
- 239000000463 material Substances 0.000 claims description 32
- 239000002904 solvent Substances 0.000 claims description 30
- 238000006243 chemical reaction Methods 0.000 claims description 22
- 238000000605 extraction Methods 0.000 claims description 19
- 239000012071 phase Substances 0.000 claims description 19
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 17
- 239000007791 liquid phase Substances 0.000 claims description 13
- 230000009471 action Effects 0.000 claims description 12
- 229910001220 stainless steel Inorganic materials 0.000 claims description 12
- 239000010935 stainless steel Substances 0.000 claims description 12
- 230000003647 oxidation Effects 0.000 claims description 10
- 238000007254 oxidation reaction Methods 0.000 claims description 10
- 230000003213 activating effect Effects 0.000 claims description 9
- 230000004913 activation Effects 0.000 claims description 9
- 230000005587 bubbling Effects 0.000 claims description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims description 9
- 238000005507 spraying Methods 0.000 claims description 9
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 8
- 238000010926 purge Methods 0.000 claims description 5
- 239000002994 raw material Substances 0.000 claims description 5
- 239000001294 propane Substances 0.000 claims description 4
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims description 4
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims description 4
- 230000008929 regeneration Effects 0.000 claims description 4
- 238000011069 regeneration method Methods 0.000 claims description 4
- 239000007795 chemical reaction product Substances 0.000 claims description 3
- 150000002431 hydrogen Chemical class 0.000 claims description 3
- 238000002347 injection Methods 0.000 claims description 3
- 239000007924 injection Substances 0.000 claims description 3
- 238000011144 upstream manufacturing Methods 0.000 claims description 3
- 238000005065 mining Methods 0.000 claims description 2
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 abstract description 6
- 238000013461 design Methods 0.000 abstract description 4
- 239000003960 organic solvent Substances 0.000 abstract description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 15
- -1 polytetrafluoroethylene Polymers 0.000 description 12
- 238000006116 polymerization reaction Methods 0.000 description 11
- 238000003795 desorption Methods 0.000 description 8
- 239000000945 filler Substances 0.000 description 8
- 238000012546 transfer Methods 0.000 description 7
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 6
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000000284 extract Substances 0.000 description 6
- 229920000642 polymer Polymers 0.000 description 6
- 239000011148 porous material Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
- LGRFSURHDFAFJT-UHFFFAOYSA-N Phthalic anhydride Natural products C1=CC=C2C(=O)OC(=O)C2=C1 LGRFSURHDFAFJT-UHFFFAOYSA-N 0.000 description 4
- JHIWVOJDXOSYLW-UHFFFAOYSA-N butyl 2,2-difluorocyclopropane-1-carboxylate Chemical compound CCCCOC(=O)C1CC1(F)F JHIWVOJDXOSYLW-UHFFFAOYSA-N 0.000 description 4
- 238000004939 coking Methods 0.000 description 4
- DOIRQSBPFJWKBE-UHFFFAOYSA-N dibutyl phthalate Chemical compound CCCCOC(=O)C1=CC=CC=C1C(=O)OCCCC DOIRQSBPFJWKBE-UHFFFAOYSA-N 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 description 3
- 230000000903 blocking effect Effects 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 239000000571 coke Substances 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 239000003112 inhibitor Substances 0.000 description 3
- 229920002521 macromolecule Polymers 0.000 description 3
- 229910052763 palladium Inorganic materials 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 238000007086 side reaction Methods 0.000 description 3
- XMTOUDRCWLYEHL-UHFFFAOYSA-N (2-bromo-3-ethoxy-6-fluorophenyl)boronic acid Chemical compound CCOC1=CC=C(F)C(B(O)O)=C1Br XMTOUDRCWLYEHL-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229920002313 fluoropolymer Polymers 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000011344 liquid material Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N 1,4-Benzenediol Natural products OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 description 1
- WJFKNYWRSNBZNX-UHFFFAOYSA-N 10H-phenothiazine Chemical compound C1=CC=C2NC3=CC=CC=C3SC2=C1 WJFKNYWRSNBZNX-UHFFFAOYSA-N 0.000 description 1
- KPYCVQASEGGKEG-UHFFFAOYSA-N 3-hydroxyoxolane-2,5-dione Chemical class OC1CC(=O)OC1=O KPYCVQASEGGKEG-UHFFFAOYSA-N 0.000 description 1
- 241001093575 Alma Species 0.000 description 1
- 238000006845 Michael addition reaction Methods 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 150000008064 anhydrides Chemical class 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- UUAGAQFQZIEFAH-UHFFFAOYSA-N chlorotrifluoroethylene Chemical group FC(F)=C(F)Cl UUAGAQFQZIEFAH-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 239000000539 dimer Substances 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 125000000687 hydroquinonyl group Chemical group C1(O)=C(C=C(O)C=C1)* 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- NWVVVBRKAWDGAB-UHFFFAOYSA-N p-methoxyphenol Chemical compound COC1=CC=C(O)C=C1 NWVVVBRKAWDGAB-UHFFFAOYSA-N 0.000 description 1
- 229950000688 phenothiazine Drugs 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000010526 radical polymerization reaction Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000013638 trimer Substances 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- 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
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to a crude maleic anhydride continuous rectification device and a process method after n-butane oxidation-organic solvent absorption and analysis, belonging to the field of maleic anhydride rectification separation. The crude maleic anhydride continuous rectification device is characterized in that one end of a distributor is connected with a crude maleic anhydride line, the other end of the distributor is connected with a light component removing tower through a pipeline, and the top of the light component removing tower is sequentially connected with a condenser at the top of the light component removing tower, a reflux tank of the light component removing tower and a vacuum system through pipelines; the bottom end of the reflux tank of the light component removal tower is sequentially connected with a reflux pump of the light component removal tower, a preheater, a mixer, a hydrogenation reactor, a gas-liquid separation tank, a propionic acid pump and a propionic acid external production line through pipelines; the bottom end of the light component removing tower is sequentially connected with a tower bottom pump of the light component removing tower, a refining tower, a tower top condenser of the refining tower, a reflux tank of the refining tower, a tail gas washing tower and a vacuum system through pipelines; the device design is scientific, and the structure is reasonable. Meanwhile, the invention also provides a process method, which is scientific, reasonable, simple and easy to implement.
Description
Technical Field
The invention relates to a crude maleic anhydride continuous rectification device and a process method after n-butane oxidation-organic solvent absorption and analysis, belonging to the field of maleic anhydride rectification separation.
Background
Maleic anhydride, also known as maleic anhydride, and dehydrated malic anhydride, is the third largest anhydride next to phthalic anhydride and acetic anhydride in the world at present. The production method of domestic maleic anhydride can be classified into benzene oxidation method and n-butane oxidation method according to raw material route. The n-butane oxidation method has the advantages of small environmental pollution, high carbon atom utilization rate, wide raw material sources, low price and the like, and in recent years, the n-butane oxidation method is gradually replaced by the benzene oxidation method to become the maleic anhydride dominant production process. With the development of large-scale intensification of maleic anhydride production, maleic anhydride post-treatment is increasingly prone to adopting a solvent absorption-desorption technology, and typical solvent absorption-desorption technologies include a Hunsman technology, a Conser technology and an ALMA technology, wherein dibutyl phthalate (DBP) is adopted as a solvent, and diisobutyl hexahydrophthalate (DIBE) is adopted as a solvent. Many research results on an oxidation process and an absorption and analysis process are reported, and the industrial application result is stable.
The crude maleic anhydride material after absorption and analysis contains acetic acid, acrylic acid, phthalic anhydride, tar and other impurities, wherein the acetic acid and the acrylic acid are normal butane oxidation byproducts, the phthalic anhydride and the tar are products of cracking and polymerization of each component in the analysis process, and at present, a continuous rectification method is mostly adopted in industry, and firstly, the acetic acid and the acrylic acid with the boiling points lower than that of the maleic anhydride are removed, and then, the heavy components are removed, so that the refined maleic anhydride is obtained. Acrylic acid in maleic anhydride is a heat-sensitive compound with unsaturated double bond at carboxyl position and has very active chemical property. At the rectifying section, the rectifying line and the condenser of the tower for removing light components from crude maleic anhydride, along with the increase of the concentration of acrylic acid, the probability of molecular collision is increased, the acrylic acid is easy to generate Michael addition reaction to generate dimers and trimers, the oligomers can further generate free radical polymerization reaction to generate high molecular polymers, the generated polymers can block pipelines, tower plates and pump bodies, and the stable operation of the device and process production can be seriously influenced. In addition, phthalic anhydride and tar substances in the crude maleic anhydride are easy to accumulate in the tower kettle of the refining tower and coke in the reboiler of the tower kettle, so that the heat exchange effect is poor. In the prior art, a method of filling polymerization inhibitor into a distillation line at the top of a light component removal tower is adopted, the polymerization inhibitor forms stable macromolecular compounds with acrylic acid to stop chain growth reaction, but the generated macromolecular compounds can accumulate and coke in a subsequent refining tower, so that serious consequences are caused, and the commonly used polymerization inhibitor is hydroquinone, p-hydroxyanisole or phenothiazine. If maleic anhydride in the tower kettle material is recovered by adopting a solvent absorption method, the generated macromolecular compound can cause the increase of solvent treatment cost.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a crude maleic anhydride continuous rectification device which can realize long-period stable operation of the crude maleic anhydride rectification device and has the characteristics of scientific design, reasonable structure, high operation elasticity and good economic performance.
Meanwhile, the invention also provides a process method adopting the crude maleic anhydride continuous rectification device, which has the advantages of being scientific, reasonable, simple and feasible, and can effectively solve the problems of acrylic acid blocking and tar coking in the process of crude maleic anhydride continuous rectification.
The invention relates to a crude maleic anhydride continuous rectification device, wherein one end of a distributor is connected with a crude maleic anhydride line, the other end of the distributor is connected with a light component removing tower through a pipeline, and the top of the light component removing tower is sequentially connected with a condenser at the top of the light component removing tower, a reflux tank of the light component removing tower and a vacuum system through pipelines; the bottom end of the reflux tank of the light component removal tower is sequentially connected with a reflux pump of the light component removal tower, a preheater, a mixer, a hydrogenation reactor, a gas-liquid separation tank, a propionic acid pump and a propionic acid external production line through pipelines; the outlet of the propionic acid pump is connected with the bottom of the distributor through a pipeline; the bottom end of the light component removing tower is sequentially connected with a tower bottom pump of the light component removing tower, a refining tower, a tower top condenser of the refining tower, a reflux tank of the refining tower, a tail gas washing tower and a vacuum system through pipelines; the upper end of the tail gas washing tower is connected with a solvent line, and the bottom of the tail gas washing tower is sequentially connected with a tower kettle pump of the tail gas washing tower and an absorption and analysis unit analysis tower through pipelines; the bottom of the refining tower reflux tank is connected with the top of the distributor through a refining tower reflux pump; the bottom of the hydrogenation reactor is provided with a regeneration tail gas line, and the top of the gas-liquid separation tank is provided with a hydrogenation tail gas line.
The reflux pump of the light component removing tower is connected with the upper end of the light component removing tower through a reflux line of the light component removing tower; the lower end of the light component removing tower is provided with a reboiler of the light component removing tower; the refining tower reflux pump is connected with the upper end of the refining tower through a refining tower reflux line; one end of the refining tower is provided with a refined maleic anhydride side picking line; the bottom of the refining tower is sequentially connected with a tower kettle pump of the refining tower and an absorption and desorption unit desorption tower through a pipeline, and the lower end of the refining tower is provided with a refining tower reboiler; the top of the mixer is connected with a heater and a hydrogen line in sequence through a pipeline, and the heater is connected with an air line and a nitrogen line at the same time.
The rectifying section of the light component removal tower adopts 4-10 sieve trays, the upstream of each sieve tray is protruded into an inclined-table-shaped bubbling accelerator, the liquid facing side of the bubbling accelerator is not provided with bubble holes, and the liquid backing side is provided with bubble holes; the sieve holes are provided with pyramid-shaped caps, each pyramid-shaped cap consists of four triangular spraying plates and a square top plate, and spraying holes are formed in the spraying plates; the spray holes of adjacent pyramid-shaped caps are positioned on different horizontal planes in the transverse and longitudinal arrangement directions.
The bubbling accelerator is higher than the column plate, the liquid layer on the bubble hole is thin, the pressure head is small, the pressure of the back liquid side is lower than that of the liquid facing side, gas is easy to pass through, good bubbling is formed, gas-liquid contact mass transfer is promoted, and each component of the liquid phase forms turbulence, so that the problem of acrylic acid polymerization caused by dead zone or laminar flow is solved. In the rectification process, liquid on the tower plate enters the cover from the periphery of the bottom gap of the cap cover, gas enters the cover body from the lower part of the tower plate through the sieve holes, the liquid is pulled and crushed into a plurality of tiny liquid drops, the gas-liquid mixture is reduced in the rising process of the bubble cap, the flow channel sectional area is reduced, the pressure energy is partially converted into kinetic energy, the flow speed of the gas-liquid mixture is accelerated, the gas-liquid mixture is ejected from the jet holes on the jet plate, the gas-liquid mixture is partially returned after the gas-liquid mixture rises to collide with the top plate, the returned gas and liquid drops are mixed with the gas-liquid mixture after the gas-liquid mixture is strongly collided with each other, the large liquid drops in the gas-liquid mixture fall back into the liquid layer, are pressed into the cover body for circulation through the bottom gap of the cap cover, the gas rises to the upper part of the cap cover and rises to the upper layer of the tower plate, the next step of heat transfer and flat heat transfer are performed, the cap cover structure develops the gas-liquid two-phase contact area into three space ranges of the inside the cover, the cover and the top cover, and strong disturbance is formed on the gas-liquid two phases, the space of the plate tower plate is fully used for eliminating the dead space or the solid flow, the problem of the tray has good aperture blocking effect due to the high-state polymerization effect, the sieve holes and the small aperture of the sieve holes are easy to be blocked by the traditional tower plate, and the problem has small aperture blocking effect is overcome. The ingenious position design of jet orifice can effectively eliminate "to spouting phenomenon" that exists when the jet orifice works, avoids the entrainment, reduces the energy consumption to improve the tray aperture ratio, make the tray area obtain make full use of, effectively reduce the back mixing of gas-liquid on every layer of tray of knockout tower, reduce the gradient of liquid level on every layer of tray of knockout tower, reduce the resistance, improve tray efficiency.
And fluorocarbon polymer is coated on the bottom surface of the tray downcomer of the rectifying section of the light component removal tower, the bottom surface of the tray, the inside of a tower top distillate line pipe of the light component removal tower, and the contact part of the tower top cooler of the light component removal tower and the tower top distillate.
The fluorocarbon polymer is one of polytetrafluoroethylene, polyvinylidene fluoride or chlorotrifluoroethylene polymer. The coating of the polymer forms a non-wetting surface on the coated surface, so that the liquid which is liable to generate the polymer is condensed into droplets and does not adhere to the surface, and the droplets are rapidly released from the surface due to the effect of self gravity, and the acrylic monomer or oligomer thereof stays on the coated surface for a short time, so that the occurrence of polymerization reaction is suppressed.
The stripping section of the light component removal tower adopts stainless steel corrugated wire mesh packing, the diameter of a packing layer is 1.5-2.5m, the height of the packing layer is 2.0-4.0m, a redistributor is arranged at the upper part of the packing layer, and a liquid collector is arranged at the lower part of the packing layer. The packing layer is positioned below the junction of the coarse maleic anhydride line and the tower body and above the junction of the tower kettle reboiler gas phase line and the tower body.
The stainless steel corrugated wire mesh filler can effectively reduce the material residence time and slow down the polymerization of acrylic acid, and in addition, the filler has higher capability of preventing liquid from entrainment.
The mixer comprises a liquid channel, a gas channel and a connecting piece, wherein the connecting piece is provided with a nanopore, and hydrogen enters a liquid material through the nanopore; the aperture of the nano-pore is 20-200nm.
The nano holes enable the gas-liquid two phases to be dispersed in the nano-scale range, so that the adsorption of acrylic acid and hydrogen on the active site of the catalyst is promoted, and the hydrogenation activity is improved; in addition, the hydrogenation of the acrylic acid is an exothermic reaction, the acrylic acid is easy to polymerize at high temperature, and under the action of the nano holes, the propionic acid, the acrylic acid and the hydrogen can be completely dispersed in the nano-scale range, so that the acrylic acid can be effectively isolated, and the polymerization of the acrylic acid in the hydrogenation process is avoided.
The refining tower is a packed tower, three packing layers are provided, the packing layers are stainless steel corrugated wire mesh, the diameter of each packing layer is 2.0-3.5m, the height of the first packing layer is 1.0-2.0m, the height of the second packing layer is 5.0-7.0m, the height of the third packing layer is 1.0-2.0m, a redistributor is arranged at the upper part of each packing layer, and a liquid collector is arranged at the lower part of each packing layer; the first packing layer is positioned below the junction of the refining tower reflux line and the tower body and above the junction of the refined maleic anhydride side extraction line and the tower body; the second packing layer is positioned below the joint of the refined maleic anhydride side production line and the tower body and above the joint of the feeding line and the tower body; the third packing layer is positioned below the joint of the feeding line and the tower body and above the joint of the gas phase line of the reboiler of the refining tower and the tower body. The stainless steel corrugated filler is selected to reduce the pressure drop of the tower, thereby reducing the temperature of the tower kettle and reducing the polymerization degree of tar.
The diameter of the notch of the liquid collector of the refining tower is smaller than the diameter of the filler, so that the residence time of tower kettle materials in the tower kettle can be shortened, and the generation of polymers is reduced.
The tail gas washing tower is a packed tower, the packing is a stainless steel corrugated wire mesh, the diameter of a packing layer is 0.5-1.5m, and the height of the packing is 1-2m; the upper part of the packing layer is provided with a redistributor, the lower part of the packing layer is provided with a liquid collector, and the packing layer is positioned above the joint of the gas phase feed line and the tower body and below the joint of the solvent line and the tower body.
The light component removing tower reboiler and the refining tower reboiler are membrane type reboilers; the top condenser of the light component removing tower and the top condenser of the refining tower are one of tube type or plate type heat exchangers.
Since the boiling point and saturated vapor pressure of the propionic acid and the acrylic acid are very close, but no vinyl functional group which is easy to initiate polymerization exists in the propionic acid, the characteristic is utilized, and the acrylic acid molecules are isolated by adding the propionic acid into the crude maleic anhydride, so that the problem of acrylic acid autopolymerization is overcome.
The overhead of the light component removal column is propionic acid, acrylic acid, acetic acid and trace maleic anhydride. Part of the materials are refluxed, and part of the materials enter a hydrogenation reactor, acetic acid is inert in the reactor, and maleic anhydride is inert in the hydrogenation reaction because of higher reaction barrier of maleic anhydride hydrogenation. The materials enter a hydrogenation reactor, and under the action of a catalyst, acrylic acid and hydrogen react as follows:
CH 2 ＝CH-COOH+H 2 →CH 3 -CH 2 -COOH (main reaction);
CH 2 ＝CH-COOH+3H 2 →CH 2 ＝CH-CH 3 +2H 2 o (side reaction);
CH 2 ＝CH-COOH+4H 2 →CH 3 -CH 2 -CH 3 +2H 2 o (side reaction);
and (3) separating the reacted gas-liquid mixture in a gas-liquid separation tank, discharging propylene, propane and unreacted hydrogen which are byproducts of the reaction, and returning the liquid-phase product propionic acid to a crude maleic anhydride line to be used as a diluting material for reuse.
The process method adopting the continuous rectification device of the crude maleic anhydride comprises the following steps:
(1) The crude maleic anhydride enters a light component removing tower along a crude maleic anhydride line through a distributor, the difference of the volatility of each component is utilized to carry out separation, a vacuum system is utilized to maintain the negative pressure of the tower system, the light component obtained from the tower top is condensed through a condenser at the tower top of the light component removing tower and then enters a reflux tank of the light component removing tower, reflux liquid is pressurized through a reflux pump of the light component removing tower, a part of reflux liquid returns to a first layer tray of the light component removing tower along a reflux line of the light component removing tower, and the other part of reflux liquid enters a mixer after being heated by a preheater; the hydrogen in the hydrogen line is preheated by a heater and then enters a mixer to be mixed with materials collected outside a reflux pump of a light component removal tower, then enters a hydrogenation reactor, acrylic acid reacts with the hydrogen under the action of a catalyst, reaction products enter a gas-liquid separation tank, unreacted gases such as hydrogen, propylene, propane and the like are discharged outside along a hydrogenation tail gas line, propionic acid enters a propionic acid tank along a pipeline, after being pressurized by a propionic acid pump, one part of the propionic acid is discharged outside the propionic acid outer collecting line, and the other part of the propionic acid returns to a distributor along the pipeline;
(2) The tower bottom materials of the light component removing tower enter a refining tower for further separation, the tower top distillate enters a reflux tank of the refining tower after being condensed by a condenser at the top of the refining tower, the uncondensed gas phase enters the lower end of a tail gas washing tower under the action of a vacuum system, the solvent enters the upper end of the tail gas washing tower along a solvent line, the gas phase and the liquid phase are in countercurrent contact in the tail gas washing tower, the maleic anhydride in the tail gas enters the solvent phase under the extraction action of the solvent, and then the maleic anhydride is externally collected to an absorption and analysis unit analysis tower after being pressurized by a tower bottom pump of the tail gas washing tower; after the liquid phase in the reflux tank of the refining tower is pressurized by a reflux pump of the refining tower, one part of the liquid phase returns to the refining tower along a reflux line of the refining tower, and the other part of the liquid phase returns to the distributor; the refined maleic anhydride is subjected to external extraction through a refined maleic anhydride side extraction line, and tower bottom materials are subjected to external extraction to an absorption and analysis unit analysis tower after being pressurized through a tower bottom pump of the refining tower;
(3) After a period of time for the hydrogenation reaction to proceed, the catalyst may be deactivated by the coverage of the active sites, and the catalyst needs to be regenerated: firstly, introducing hot nitrogen to blow off a bed layer, then introducing hot air, and finally introducing activating gas to activate a catalyst; the temperature of the reactor is controlled by a heater in the whole process, the purge gas, the roasting gas and the activating gas are discharged through a regenerated tail gas line, and raw materials and hydrogen are introduced into the hydrogenation reactor for reaction after the activation is finished.
In the step 1, the mass ratio of propionic acid to acrylic acid at the feeding tower plate of the light component removal tower is 20-200:1; the pressure at the top of the light component removing tower is-100-70 KPa, the pressure at the bottom of the light component removing tower is-90-60 KPa, and the reflux ratio of the light component removing tower is 0.7-4:1.
In the step 2, the top pressure of the refining tower is-100-70 KPa, and the bottom pressure is-95-65 KPa; the reflux ratio of the refining tower is 5-20:1.
The temperature of the top of the light component removing tower is 110-140 ℃, and the temperature of the bottom of the tower is 140-170 ℃; the temperature of the top of the refining tower is 110-130 ℃, and the temperature of the bottom of the refining tower is 120-140 ℃; the side extraction temperature of the refining tower is 112-132 ℃; the temperature of the tail gas washing tower is 60-80 ℃; the mass ratio of the solvent in the tail gas washing tower to the maleic anhydride in the tail gas is 0.2-1:1.
In the hydrogenation reaction process, the hydrogen is mixed with the acrylic acid and the propionic acid through a mixer, and the molar ratio of the acrylic acid to the hydrogen to the propionic acid in the hydrogenation process is 1:1-100:1-100, preferably 1:1-20:10-40. The propionic acid and the hydrogen can timely take away the heat released by the reaction, play the role of a heat carrier, and effectively avoid side reactions caused by high temperature.
The hydrogenation reaction conditions are as follows: the reaction pressure is 1-2MPa, the reaction temperature is 40-80 ℃, and the volume space velocity of the acrylic acid is 0.1-2h -1 The molar ratio of hydrogen to acrylic acid in the feed is 1-100:1, preferably 1-20:1.
The hydrogenation catalyst is a supported catalyst, and the active component is one or more of palladium, platinum, nickel, molybdenum or ruthenium with the content of 0.2-1 wt%; the carrier is alumina or silicon oxide, the specific surface area of the catalyst is 50-150m 2 And/g, the pore diameter is 10-50nm.
In the step 3, the purging temperature is 60-200 ℃ and the roasting temperature is 300-400 ℃. The active components of the catalyst new agent or regenerated catalyst are in an oxidation state, and the catalyst is activated by introducing a reducing gas before the reaction, wherein the activating gas is one of hydrogen or hydrogen/nitrogen mixed gas; the activation temperature is 200-350 ℃, the activation pressure is 0-0.2MPa, and the hydrogen volume airspeed is 1000-1500h -1 。
The material at the bottom of the refining tower consists of maleic anhydride and heavy components, the part of the material returns to the absorption and analysis unit to analyze the tower, the maleic anhydride and the heavy components are separated by utilizing different boiling points, and the high-boiling-point tar compound enters a solvent phase and is removed by a solvent treatment unit.
The materials in the extraction line of the tower kettle of the refining tower enter the absorption and desorption unit to be desorbed, and the method for reducing the temperature of the tower kettle and improving the extraction amount of the extraction line of the tower kettle of the refining tower reduces the temperature of the tower kettle, shortens the residence time of tar in the materials of the tower kettle in the tower kettle, and reduces the generation of cokes.
Compared with the prior art, the invention has the following beneficial effects:
1. the continuous crude maleic anhydride rectifying device is scientific in design and reasonable in structure, can realize long-period stable operation, and has the advantages of high operation elasticity and good economic performance;
2. the process method provided by the invention is scientific, reasonable, simple and feasible, can effectively overcome the problems of acrylic acid hanging blockage and tar coking, and the rectification process does not cause secondary pollution to maleic anhydride, and the obtained refined maleic anhydride has high yield and high purity.
Drawings
FIG. 1 is a schematic structural diagram of a crude maleic anhydride continuous rectification apparatus;
FIG. 2 is a schematic diagram of a tray plate structure of a sieve tray;
FIG. 3 is a schematic view of the structure of a pyramid-shaped cap;
FIG. 4 is a schematic top view of a pyramidal cap;
in the figure, 1-crude maleic anhydride line; a 2-distributor; 3-a light component removing tower; 4-a tower bottom pump of the light component removing tower; 5-a condenser at the top of the light component removing tower; 6-a reflux tank of the light component removing tower; 7-a reflux drum of the light component removal tower; 8-a light component removal tower reboiler; 9-a reflux pump of the light component removing tower; 10-a preheater; 11-a regeneration tail gas line; 12-air line; 13-nitrogen line; 14-hydrogen line; 15-a heater; 16-a mixer; 17-a hydrogenation reactor; 18-a gas-liquid separation tank; 19-hydrogenation tail gas line; a 20-propionic acid tank; a 21-propionic acid pump; 22-propionic acid outer picking line; 23-a refining tower; 24-a condenser at the top of the refining tower; 25-a reflux drum of the refining tower; 26-a reflux pump of the refining tower; 27-a refining column reflux line; 28-fine maleic anhydride side extraction line; 29-a rectifying column reboiler; 30-a tower bottom pump of the refining tower; 31-a tail gas washing tower; 32-a tail gas washing tower kettle pump; 33-an absorption and analysis unit analysis tower; 34-a vacuum system; 35-solvent line; 36-removing light component tower body; 37-bubbling holes; 38-a bubbling accelerator; 39-pyramid cap; 40-downcomer; 41-mesh; 42-column plate; 43-top plate; 44-a jet plate; 45-injection hole.
Detailed Description
The invention is further described below with reference to the accompanying drawings and examples.
Example 1
The crude maleic anhydride continuous rectification device is characterized in that one end of a distributor 2 is connected with a crude maleic anhydride line 1, the other end of the distributor is connected with a light component removing tower 3 through a pipeline, and the top of the light component removing tower 3 is sequentially connected with a light component removing tower top condenser 5, a light component removing tower reflux tank 6 and a vacuum system 34 through pipelines; the bottom end of the light component removal tower reflux tank 6 is sequentially connected with a light component removal tower reflux pump 9, a preheater 10, a mixer 16, a hydrogenation reactor 17, a gas-liquid separation tank 18, a propionic acid tank 20, a propionic acid pump 21 and an acid external production line 22 through pipelines; the outlet of the acid pump 21 is connected with the bottom of the distributor 2 through a pipeline; the bottom end of the light component removing tower 3 is connected with a tower kettle pump 4 of the light component removing tower, a refining tower 23, a tower top condenser 24 of the refining tower, a refining tower reflux tank 25, a tail gas washing tower 31 and a vacuum system 34 in sequence through pipelines; the upper end of the tail gas washing tower 31 is connected with a solvent line 35, and the bottom is sequentially connected with a tail gas washing tower kettle pump 32 and an absorption and analysis unit analysis tower 33 through pipelines; the bottom of the refining tower reflux tank 25 is connected with the top of the distributor 2 through a refining tower reflux pump 26; the bottom of the hydrogenation reactor 17 is provided with a regeneration tail gas line 11, and the top of the gas-liquid separation tank is provided with a hydrogenation tail gas line 19.
The reflux pump 9 of the light component removing tower is connected with the upper end of the light component removing tower 3 through a reflux line 7 of the light component removing tower; the lower end of the light component removing tower is provided with a light component removing tower reboiler 8; the refining tower reflux pump 26 is connected with the upper end of the refining tower 23 through a refining tower reflux line 27; one end of the refining tower 23 is provided with a refined maleic anhydride side extraction line 28; the bottom of the refining tower 23 is sequentially connected with a refining tower kettle pump 30 and an absorption and desorption unit desorption tower through pipelines, and the lower end of the refining tower is provided with a refining tower reboiler 29; the top of the mixer 16 is connected with the heater 15 and the hydrogen line 14 in turn through pipelines, and the heater 15 is connected with the air line 12 and the nitrogen line 13 at the same time.
The rectifying section of the light component removing tower 3 adopts 4-10 sieve trays, the upstream of each tray 42 is protruded into an inclined table-shaped bubbling accelerator 38, the bubbling accelerator 38 has no bubble holes 37 on the liquid facing side, and the bubble holes 37 are arranged on the liquid back side; the sieve holes 41 are provided with pyramid-shaped caps 39, the pyramid-shaped caps 39 are composed of four triangular spraying plates 44 and a square top plate 43, and spraying holes 45 are arranged on the spraying plates 44; the injection holes 45 of adjacent pyramid-shaped caps 39 are at different levels in both the lateral and longitudinal alignment directions.
Polytetrafluoroethylene is coated on the tray downcomer of the rectifying section of the light component removal tower, the bottom surface of the tray, the inside of a tower top distillate line pipe of the light component removal tower, a tower top cooler of the light component removal tower and a tower top distillate contact part.
The stripping section of the light component removing tower adopts stainless steel corrugated wire mesh packing, the diameter of a packing layer is 1.5m, the height of the packing is 2.0m, and the packing is stainless steel corrugated wire mesh. The upper part of the packing layer is provided with a redistributor, the lower part of the packing layer is provided with a liquid collector, and the packing layer is positioned below the joint of the coarse maleic anhydride line 1 and the tower body and above the joint of the tower kettle reboiler gas phase line and the tower body.
The refining tower 23 is a packed tower, and is provided with three packing layers, wherein the packing layers are stainless steel corrugated wire meshes, the diameters of the packing layers are 2.0-3.5m, the heights of the first packing layers are 1.0-2.0m, the heights of the second packing layers are 5.0-7.0m, the heights of the third packing layers are 1.0-2.0m, a redistributor is arranged at the upper part of each packing layer, and a liquid collector is arranged at the lower part of each packing layer; wherein, the first packing layer is positioned below the junction of the refining tower return line 27 and the tower body and above the junction of the refined maleic anhydride side extraction line 28 and the tower body; the second packing layer is positioned below the junction of the refined maleic anhydride side production line 28 and the tower body and above the junction of the feed line and the tower body; the third packing layer is positioned below the joint of the feeding line and the tower body and above the joint of the gas phase line of the refining tower reboiler 29 and the tower body. The diameter of the liquid collecting tank of the refining tower is smaller than the diameter of the packing.
The mixer 16 includes a liquid channel, a gas channel, and a connector with a nanopore, and hydrogen gas enters the liquid material through the nanopore, and the pore diameter of the nanopore is 20nm.
The light component removing tower reboiler 8 and the refining tower reboiler 29 adopt film type reboilers, and the light component removing tower top condenser 5 and the refining tower top condenser 24 are tubular heat exchangers.
The tail gas washing tower 31 is a packed tower, the packing is a stainless steel corrugated wire mesh, the diameter of a packing layer is 0.5-1.5m, and the height of the packing layer is 1-2m; the upper part of the packing layer is provided with a redistributor, the lower part is provided with a liquid collector, and the packing layer is positioned above the joint of the gas phase feeding line and the tower body and below the joint of the solvent line 35 and the tower body.
The composition of the crude maleic anhydride material from the absorption and desorption unit is shown in table 1; propionic acid is added into the light component removing tower, the mass ratio of the propionic acid to the acrylic acid at the tower plate of the feeding tower of the light component removing tower is 20:1 by adjusting, and the material composition is shown in table 2:
TABLE 1 crude maleic anhydride composition
| Composition of the components | H 2 O | Acetic acid | Acrylic acid | Maleic anhydride | Heavy component |
| Composition (wt.) | 0.10 | 0.30 | 1.20 | 98.30 | 0.10 |
TABLE 2 composition of the materials entering the light ends removal column
| Composition of the components | H 2 O | Acetic acid | Propionic acid | Acrylic acid | Maleic anhydride | Heavy component |
| Composition (wt.) | 0.08 | 0.24 | 19.40 | 0.97 | 79.23 | 0.08 |
The process method adopting the continuous rectification device for crude maleic anhydride comprises the following steps:
(1) The crude maleic anhydride material enters a light component removing tower 3 along a crude maleic anhydride line 1 through a distributor 2, the separation is carried out by utilizing the difference of the volatilities of all components under the thermal driving action of a reboiler 8 of the light component removing tower, the vacuum system 34 maintains the negative pressure of the tower system, the light component obtained from the tower top is condensed by a condenser 5 at the tower top of the light component removing tower and enters a reflux tank 6 of the light component removing tower, the reflux liquid is pressurized by a reflux pump 9 of the light component removing tower, one part of the reflux liquid returns to a first tray of the light component removing tower 3 along a reflux line of the light component removing tower, and the other part of the reflux liquid enters a mixer 16 after being heated by a preheater 10; the top pressure of the light component removing tower is-70 KPa, the bottom pressure of the light component removing tower is-60 KPa, the top temperature of the tower is 110 ℃, the bottom temperature of the tower is 140 ℃, and the reflux ratio is 4. The hydrogen in the hydrogen line 14 is preheated by the heater 15 and then enters the mixer 16,mixing the mixture with the external material of the reflux pump 9 of the light component removing tower, then entering a hydrogenation reactor 17, reacting acrylic acid with hydrogen under the action of a catalyst, allowing the reaction product to enter a gas-liquid separation tank 18, discharging unreacted hydrogen, propylene, propane and other gases along a hydrogenation tail gas line 19, allowing propionic acid to enter a propionic acid tank 20 along a pipeline, pressurizing by a propionic acid pump 21, discharging a part of the propionic acid along a propionic acid external material collecting line 22, and returning the other part of the propionic acid along the pipeline to the distributor 2; wherein, the hydrogenation reaction conditions are as follows: the reaction pressure is 2Mpa, the reaction temperature is 40 ℃, and the volume space velocity of the acrylic acid is 2h -1 The molar ratio of hydrogen to acrylic acid in the feed was 20; the hydrogenation catalyst is a supported catalyst, the active component is palladium, the catalyst carrier is silicon oxide, the total content of the active components is 1wt%, and the specific surface area of the catalyst is 50m 2 And/g, pore diameter of 50nm. At this time, the conversion of acrylic acid was 99.8%, and the selectivity of the product propionic acid was 99.5%.
After separation, the composition of the column overhead and bottom components of the light component removal column is shown in tables 3 and 4:
TABLE 3 light ends column overhead composition
| Composition of the components | Acetic acid | Propionic acid | Acrylic acid | Maleic anhydride |
| Composition (wt.) | 1.14 | 92.38 | 4.62 | 0.23 |
TABLE 4 composition of the bottom materials of the light ends removal column
| Composition of the components | Propionic acid | Acrylic acid | Maleic anhydride | Heavy component |
| Composition (wt.) | 0.20 | 0.02 | 99.66 | 0.12 |
(2) The tower bottom material of the light component removing tower 3 enters a refining tower 23 for further separation, the tower top distillate enters a refining tower 25 after being condensed by a tower top condenser 24 of the refining tower, the uncondensed gas phase enters the lower end of a tail gas washing tower 31 under the action of a vacuum system 34, the solvent enters the upper end of the tail gas washing tower 31 along a solvent line 35, the gas phase and the liquid phase are in countercurrent contact in the tail gas washing tower 31, the maleic anhydride in the tail gas enters the solvent phase under the extraction action of the solvent, and then is externally collected to an absorption and analysis unit analysis tower 33 after being pressurized by a tower bottom pump 32 of the tail gas washing tower; after the liquid phase in the refining tower reflux drum 25 is pressurized by the refining tower reflux pump 26, a part of the liquid phase returns to the refining tower 23 along the refining tower reflux line 27, and the other part returns to the distributor 2; the refined maleic anhydride is extracted outside through a refined maleic anhydride side extraction line 28, and the tower bottom material is pressurized through a refining tower kettle pump 30 and then is extracted outside to an absorption and analysis unit analysis tower 33; wherein the pressure at the top of the refining tower 23 is-70 KPa, the pressure at the bottom of the refining tower is-65 KPa, the temperature at the top of the refining tower is 110 ℃, the temperature at the bottom of the refining tower is 120 ℃, the side mining temperature is 112 ℃, and the reflux ratio of the refining tower is 5; the tail gas washing tower temperature is 60 ℃, the mass ratio of the solvent to the maleic anhydride in the tail gas is 0.2, and at the moment, the recovery rate of the maleic anhydride in the tail gas is 99.9%.
(3) After a period of time for the hydrogenation reaction to proceed, the catalyst may be deactivated by the coverage of the active sites, and the catalyst needs to be regenerated: firstly, introducing hot nitrogen to blow off a bed layer, then introducing hot air, and finally introducing activating gas to activate a catalyst; the temperature of the reactor is controlled by a heater in the whole process, the purge gas, the roasting gas and the activating gas are discharged through a regenerated tail gas line, and raw materials and hydrogen are introduced into the hydrogenation reactor for reaction after the activation is finished.
In step 3, the purge temperature was 100℃and the firing temperature was 350 ℃.
The active components of the catalyst new agent or regenerated catalyst are in an oxidation state, and the catalyst is activated by introducing reducing gas before the reaction, wherein the activating gas is hydrogen; the activation temperature is 200 ℃, the activation pressure is-0.2 MPa, and the hydrogen volume space velocity is 1500h -1 。
After separation, the column overhead and column extract compositions are shown in tables 5, 6 and 7, respectively:
TABLE 5 refining column overhead composition
| Composition of the components | Propionic acid | Acrylic acid | Maleic anhydride |
| Composition (wt.) | 0.21 | 0.02 | 99.77 |
TABLE 6 composition of side-produced products of refining columns
| Composition of the components | Maleic anhydride |
| Composition (wt.) | 99.92 |
TABLE 7 composition of extract from bottom of refining column
| Composition of the components | Maleic anhydride | Heavy component |
| Composition (wt.) | 99.88 | 0.12 |
In the embodiment, the device runs continuously and stably for 10 months, the pressure difference of the light component removal tower is maintained at 10-20KPa, no large fluctuation occurs, and the composition of the tower top and tower bottom extracts is stable, which indicates that the acrylic acid hanging block does not occur on the light component removal tower plate, and the heat and mass transfer are not affected. The flow rate of the heating medium of the reboiler at the bottom of the refining tower is stable, which means that the problem of poor heat transfer effect of the reboiler of the refining tower caused by coking of tar substances does not occur.
The hydrogenation reactor was operated for 8 months.
Example 2
The crude maleic anhydride continuous rectification device and the process method are the same as those in the embodiment 1, and the difference is that: the composition of the crude maleic anhydride material from the absorption and analysis unit is shown in Table 1, and propionic acid is added into the light component removal column, and the mass ratio of propionic acid to acrylic acid in the material entering the light component removal column is adjusted to be 200:1, the material composition is shown in table 2:
TABLE 1 crude maleic anhydride composition
| Composition of the components | H 2 O | Acetic acid | Acrylic acid | Maleic anhydride | Heavy component |
| Composition (wt.) | 0.10 | 0.10 | 1.50 | 98.00 | 0.40 |
TABLE 2 composition of the materials entering the light ends removal column
| Composition of the components | H 2 O | Acetic acid | Propionic acid | Acrylic acid | Maleic anhydride | Heavy component |
| Composition (wt.) | 0.03 | 0.03 | 74.96 | 0.38 | 24.5 | 0.10 |
The top pressure of the light component removing tower is-100 KPa, the bottom pressure is-90 KPa, the top temperature of the tower is 140 ℃, the bottom temperature of the tower is 170 ℃, the reflux ratio is 0.7, and the rectifying section of the light component removing tower adopts a sieve tray for 10 blocks; the stripping section of the light component removing tower adopts a filler, the diameter of a filler layer is 2.5m, and the height of the filler is 4m; the aperture of the nano-pore in the mixer is 200nm; the tail gas washing tower is a packed tower, the diameter of a packing layer is 0.5m, and the height of the packing is 1m.
The light component removing tower reboiler and the refining tower reboiler adopt film type reboilers, and the top condenser of the light component removing tower and the top condenser of the refining tower are plate type heat exchangers.
The refining tower is a packed tower, three packing layers are provided, the packing is a stainless steel corrugated wire mesh, the diameter of the packing layers is 3.5m, the height of the first packing layer is 2.0m, and the height of the second packing layer is 7.0m; the third filler layer had a height of 2.0m.
The hydrogenation reaction conditions are as follows: the reaction pressure is 1Mpa, the reaction temperature is 80 ℃, and the space velocity of the acrylic acid is 1h -1 The molar ratio of hydrogen to acrylic acid in the feed is 1:1, the hydrogenation catalyst is a supported catalyst, the active component is palladium, the catalyst carrier is alumina, the total content of the active components is 0.2wt%, and the specific surface area of the catalyst is 150m 2 And/g, pore diameter of 10nm. The conversion of acrylic acid was 99.5% and the selectivity of the product propionic acid was 99.2%.
The pressure at the top of the refining tower is-100 KPa, the pressure at the bottom of the refining tower is-95 KPa, the temperature at the top of the refining tower is 130 ℃, the temperature at the bottom of the refining tower is 140 ℃, the side recovery temperature is 132 ℃, and the reflux ratio is 20.
The temperature of the tail gas washing tower is 80 ℃; the mass ratio of the solvent to the tail gas is 1; the recovery rate of maleic anhydride in the tail gas is 99.9%.
After separation, the column top and bottom distillates of the light component removal column are shown in tables 3 and 4, respectively:
TABLE 3 light ends column overhead composition
| Composition of the components | Acetic acid | Propionic acid | Acrylic acid | Maleic anhydride |
| Composition (wt.) | 0.04 | 99.00 | 0.46 | 0.26 |
TABLE 4 composition of the bottom materials of the light ends removal column
| Composition of the components | Propionic acid | Acrylic acid | Maleic anhydride | Heavy component |
| Composition (wt.) | 0.38 | ---- | 99.22 | 0.40 |
After separation, the top and bottom extracts of the refining tower are shown in tables 5, 6 and 7 respectively:
TABLE 5 refining column overhead composition
| Composition of the components | Propionic acid | Acrylic acid | Maleic anhydride |
| Composition (wt.) | 0.40 | ----- | 99.60 |
TABLE 6 composition of side-produced products of refining columns
| Composition of the components | Maleic anhydride |
| Composition (wt.) | 99.9 |
TABLE 7 composition of extract from bottom of refining column
| Composition of the components | Maleic anhydride | Heavy component |
| Composition (wt.) | 99.60 | 0.40 |
In the embodiment, the device runs continuously and stably for 12 months, the pressure difference of the light component removal tower is maintained at 10-20KPa, no large fluctuation occurs, and the composition of the tower top and tower bottom extracts is stable, which indicates that the acrylic acid hanging block does not occur on the light component removal tower plate, and the heat and mass transfer are not affected. The flow rate of the heating medium of the reboiler at the bottom of the refining tower is stable, which means that the problem of poor heat transfer effect of the reboiler of the refining tower caused by coking of tar substances does not occur.
The hydrogenation reactor run time was 9 months.
Claims (8)
1. A crude maleic anhydride continuous rectification device is characterized in that: one end of the distributor (2) is connected with a coarse maleic anhydride line (1), the other end of the distributor is connected with a light component removing tower (3) through a pipeline, and the top of the light component removing tower (3) is sequentially connected with a light component removing tower top condenser (5), a light component removing tower reflux tank (6) and a vacuum system (34) through pipelines; the bottom end of the light component removal tower reflux tank (6) is sequentially connected with a light component removal tower reflux pump (9), a preheater (10), a mixer (16), a hydrogenation reactor (17), a gas-liquid separation tank (18), a propionic acid tank (20), a propionic acid pump (21) and a propionic acid external production line (22) through pipelines; the outlet of the propionic acid pump (21) is connected with the bottom of the distributor (2) through a pipeline; the bottom end of the light component removing tower (3) is sequentially connected with a tower kettle pump (4) of the light component removing tower, a refining tower (23), a tower top condenser (24) of the refining tower, a reflux tank (25) of the refining tower, a tail gas washing tower (31) and a vacuum system (34) through pipelines; the upper end of the tail gas washing tower (31) is connected with a solvent line (35), and the bottom of the tail gas washing tower is sequentially connected with a tower kettle pump (32) of the tail gas washing tower and an absorption and analysis unit analysis tower (33) through pipelines; the bottom of the refining tower reflux tank (25) is connected with the top of the distributor (2) through a refining tower reflux pump (26); a regeneration tail gas line (11) is arranged at the bottom of the hydrogenation reactor (17), a hydrogenation tail gas line (19) is arranged at the top of the gas-liquid separation tank (18),
the reflux pump (9) of the light component removing tower is connected with the upper end of the light component removing tower (3) through a reflux line (7) of the light component removing tower; the lower end of the light component removing tower (3) is provided with a light component removing tower reboiler (8); the refining tower reflux pump (26) is connected with the upper end of the refining tower (23) through a refining tower reflux line (27); one end of the refining tower (23) is provided with a refined maleic anhydride side mining line (28); the bottom of the refining tower (23) is sequentially connected with a refining tower kettle pump (30) and an absorption and analysis unit analysis tower (33) through pipelines, and a refining tower reboiler (29) is arranged at the lower end of the refining tower (23); the top of the mixer (16) is connected with a heater (15) and a hydrogen line (14) in sequence through pipelines, the heater (15) is connected with an air line (12) and a nitrogen line (13) at the same time,
the rectifying section of the light component removing tower (3) adopts 4-10 sieve trays, wherein the upstream of each tray (42) is protruded into an inclined table-shaped bubbling accelerator (38), the bubbling accelerator (38) has no bubble holes (37) on the liquid facing side, and the bubble holes (37) are arranged on the liquid backing side; the sieve holes (41) are provided with pyramid-shaped caps (39), the pyramid-shaped caps (39) are composed of four triangular spraying plates (44) and a square top plate (43), and spraying holes (45) are formed in the spraying plates (44); the injection holes (45) of adjacent pyramid-shaped caps (39) are located at different levels in the two directions of alignment.
2. The continuous rectification apparatus of crude maleic anhydride as claimed in claim 1, wherein: the refining tower (23) is a packed tower, three packing layers are all arranged, the packing layers are stainless steel corrugated wire meshes, the diameters of the packing layers are 2.0-3.5m, the heights of the first packing layers are 1.0-2.0m, the heights of the second packing layers are 5.0-7.0m, the heights of the third packing layers are 1.0-2.0m, a redistributor is arranged at the upper part of each packing layer, and a liquid collector is arranged at the lower part of each packing layer.
3. The continuous rectification apparatus of crude maleic anhydride as claimed in claim 1, wherein: the tail gas washing tower (31) is a packed tower, the packing layer is a stainless steel corrugated wire mesh, the diameter of the packing layer is 0.5-1.5m, and the height of the packing layer is 1-2m; the upper part of the packing layer is provided with a redistributor, and the lower part is provided with a liquid collector.
4. A process for the continuous rectification of crude maleic anhydride using the apparatus of claim 1, characterized in that: the method comprises the following steps:
(1) The crude maleic anhydride enters a light component removing tower along a crude maleic anhydride line through a distributor, the difference of the volatility of each component is utilized to carry out separation, a vacuum system is utilized to maintain the negative pressure of the tower system, the light component obtained from the tower top is condensed through a condenser at the tower top of the light component removing tower and then enters a reflux tank of the light component removing tower, reflux liquid is pressurized through a reflux pump of the light component removing tower, a part of reflux liquid returns to a first layer tray of the light component removing tower along a reflux line of the light component removing tower, and the other part of reflux liquid enters a mixer after being heated by a preheater; the hydrogen in the hydrogen line is preheated by a heater and then enters a mixer to be mixed with materials collected outside a reflux pump, then enters a hydrogenation reactor, acrylic acid reacts with the hydrogen under the action of a catalyst, the reaction product enters a gas-liquid separation tank, unreacted hydrogen, propylene and propane gas are discharged along a hydrogenation tail gas line, propionic acid enters a propionic acid tank along a pipeline, after being pressurized by a propionic acid pump, one part of the propionic acid is discharged along a propionic acid collecting line, and the other part of the propionic acid returns to a distributor along the pipeline;
(2) The tower bottom materials of the light component removing tower enter a refining tower for further separation, the tower top distillate enters a reflux tank of the refining tower after being condensed by a condenser at the top of the refining tower, the uncondensed gas phase enters the lower end of a tail gas washing tower under the action of a vacuum system, the solvent enters the upper end of the tail gas washing tower along a solvent line, the gas phase and the liquid phase are in countercurrent contact in the tail gas washing tower, the maleic anhydride in the tail gas enters the solvent phase under the extraction action of the solvent, and then the maleic anhydride is externally collected to an absorption and analysis unit analysis tower after being pressurized by a tower bottom pump of the tail gas washing tower; after the liquid phase in the reflux tank of the refining tower is pressurized by a reflux pump of the refining tower, one part of the liquid phase returns to the refining tower along a reflux line of the refining tower, and the other part of the liquid phase returns to the distributor; the refined maleic anhydride is subjected to external extraction through a refined maleic anhydride side extraction line, and tower bottom materials are subjected to external extraction to an absorption and analysis unit analysis tower after being pressurized through a tower bottom pump of the refining tower;
(3) After a period of time for the hydrogenation reaction to proceed, the catalyst may be deactivated by the coverage of the active sites, and the catalyst needs to be regenerated: firstly, introducing hot nitrogen to blow off a bed layer, then introducing hot air, and finally introducing activating gas to activate a catalyst; the temperature of the reactor is controlled by a heater in the whole process, the purge gas, the roasting gas and the activating gas are discharged through a regenerated tail gas line, and raw materials and hydrogen are introduced into the hydrogenation reactor for reaction after the activation is finished.
5. The process of the continuous rectification apparatus for crude maleic anhydride according to claim 4, wherein: in the step 1, the mass ratio of propionic acid to acrylic acid at the feeding tower plate of the light component removing tower is 20-200:1, the pressure at the top of the light component removing tower is-100-70 KPa, the pressure at the bottom of the tower is-90-60 KPa, and the reflux ratio of the light component removing tower is 0.7-4:1; in the step 2, the pressure at the top of the refining tower is-100 to-70 KPa, and the pressure at the bottom of the refining tower is-95 to-65 KPa; the reflux ratio of the refining tower is 5-20:1.
6. The process of the continuous rectification apparatus for crude maleic anhydride according to claim 4, wherein: the hydrogenation reaction conditions in the hydrogenation reactor are as follows: the reaction pressure is 1-2MPa, the reaction temperature is 40-80 ℃, and the volume space velocity of the acrylic acid is 0.1-2h -1 The molar ratio of hydrogen to acrylic acid in the feed is 1-100:1.
7. The process of the continuous rectification apparatus for crude maleic anhydride according to claim 4, wherein: the temperature of the top of the light component removing tower is 110-140 ℃, and the temperature of the bottom of the tower is 140-170 ℃; the temperature of the top of the refining tower is 110-130 ℃, and the temperature of the bottom of the refining tower is 120-140 ℃; the side extraction temperature of the refining tower is 112-132 ℃; the temperature of the tail gas washing tower is 60-80 ℃; the mass ratio of the solvent in the tail gas washing tower to the maleic anhydride in the tail gas is 0.2-1:1.
8. The process of the continuous rectification apparatus for crude maleic anhydride according to claim 4, wherein: the active components of the catalyst are in oxidation state, and the catalyst is activated by introducing reducing gas before reaction, wherein the activating gas is hydrogen or hydrogenOne of the gas/nitrogen mixtures; the activation temperature is 200-350 ℃, the activation pressure is 0-0.2MPa, and the hydrogen volume airspeed is 1000-1500h -1 。
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| CN115121010B (en) * | 2022-06-29 | 2023-09-22 | 万辅工程设计有限公司 | Degassing tower, polymerization glue solution degassing treatment device and method |
| CN117504545A (en) * | 2024-01-08 | 2024-02-06 | 常州瑞华化工工程技术股份有限公司 | Device and method for obtaining maleic anhydride from gas phase containing maleic anhydride |
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