CN114146439A - Double-falling-film evaporation rectifying tower system and rectifying method thereof - Google Patents
Double-falling-film evaporation rectifying tower system and rectifying method thereof Download PDFInfo
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- 239000011552 falling film Substances 0.000 title claims abstract description 79
- 238000001704 evaporation Methods 0.000 title claims abstract description 26
- 230000008020 evaporation Effects 0.000 title claims abstract description 26
- 238000000034 method Methods 0.000 title claims abstract description 26
- 239000002994 raw material Substances 0.000 claims abstract description 29
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000007788 liquid Substances 0.000 claims description 41
- 238000010992 reflux Methods 0.000 claims description 27
- 239000003054 catalyst Substances 0.000 claims description 19
- 239000003446 ligand Substances 0.000 claims description 19
- 238000000605 extraction Methods 0.000 claims description 18
- CFEYBLWMNFZOPB-UHFFFAOYSA-N Allylacetonitrile Natural products C=CCCC#N CFEYBLWMNFZOPB-UHFFFAOYSA-N 0.000 claims description 17
- 238000006243 chemical reaction Methods 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 10
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 claims description 9
- WBAXCOMEMKANRN-UHFFFAOYSA-N 2-methylbut-3-enenitrile Chemical compound C=CC(C)C#N WBAXCOMEMKANRN-UHFFFAOYSA-N 0.000 claims description 4
- UVKXJAUUKPDDNW-NSCUHMNNSA-N (e)-pent-3-enenitrile Chemical compound C\C=C\CC#N UVKXJAUUKPDDNW-NSCUHMNNSA-N 0.000 claims description 3
- 238000009826 distribution Methods 0.000 claims description 3
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- 239000010408 film Substances 0.000 description 8
- 239000007789 gas Substances 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 4
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- 238000005669 hydrocyanation reaction Methods 0.000 description 4
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- 238000006317 isomerization reaction Methods 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- IHXNSHZBFXGOJM-HWKANZROSA-N (e)-2-methylbut-2-enenitrile Chemical compound C\C=C(/C)C#N IHXNSHZBFXGOJM-HWKANZROSA-N 0.000 description 2
- ISBHMJZRKAFTGE-ONEGZZNKSA-N (e)-pent-2-enenitrile Chemical compound CC\C=C\C#N ISBHMJZRKAFTGE-ONEGZZNKSA-N 0.000 description 2
- FPPLREPCQJZDAQ-UHFFFAOYSA-N 2-methylpentanedinitrile Chemical compound N#CC(C)CCC#N FPPLREPCQJZDAQ-UHFFFAOYSA-N 0.000 description 2
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- 229910052751 metal Inorganic materials 0.000 description 1
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- 229920001778 nylon Polymers 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
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- 229910052723 transition metal Inorganic materials 0.000 description 1
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
- B01D3/322—Reboiler specifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/42—Regulation; Control
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a double-falling-film evaporation rectifying tower system, which comprises a rectifying tower, a first falling-film reboiler and a second falling-film reboiler, wherein the rectifying tower comprises a tower kettle, a stripping section, a rectifying section and a tower top which are sequentially connected from bottom to top; the invention also discloses a method for rectifying by using the double-falling-film evaporation rectifying tower system, and the double-falling-film evaporation rectifying tower system can effectively rectify the raw material containing the nickel catalyst and has higher popularization value.
Description
Technical Field
The invention belongs to the technical field of chemistry, and particularly relates to a double-falling-film evaporation rectifying tower system and a rectifying method thereof.
Background
Adiponitrile, an important chemical intermediate in the industrial production of nylon polyphthalamines, which are useful for forming films, fibers, and molded articles, is obtained by double hydrocyanation of 1, 3-butadiene.
A process for the preparation of adiponitrile, which is currently commercially available, is obtained by several process routes in the presence of transition metal complexes comprising various phosphorus-containing ligands.
The abbreviation used for the above formula, BD is 1, 3-butadiene, HC ≡ N is hydrogen cyanide, and 2M3BN is 2-methyl-3-butenenitrile. The chemical process for producing 3PN by BD hydrocyanation involves catalytic isomerization of 2M3BN to 3PN in the presence of NiL4 complex (chemical equation 2 above). By-products of BD hydrocyanation and 2M3BN isomerization may include 4-pentenenitrile (4PN), 2-pentenenitrile (2PN), 2-methyl-2-butenenitrile (2M2BN), and 2-Methylglutaronitrile (MGN).
The production process described above relates to a process for recovering the catalyst from the extract by distillation, the catalyst mixture being recovered and reused in the hydrocyanation or isomerization stage. In the removal of the extractant for catalyst recovery, in particular of the complexing ligand, it is possible to achieve an effective depletion of the extractant from the high-boiling catalyst stream. The extractant, which has a relatively low boiling point, is condensed with conventional cooling water at a temperature of 25 c to 50 c at the top of the distillation column. In this process step, which results in very little thermal damage to the material to be evaporated, the evaporator associated with the distillation apparatus, for example a thin-film evaporator or short-path evaporator, is realized by the short contact time of the material on the evaporator surface and the very low temperature of the evaporator surface. The thin film evaporator or short path evaporator is characterized by high vacuum degree, so that the gas density on the liquid surface is reduced, the average free path of molecules is possibly larger than the distance between the evaporation surface and the condensation surface, the evaporation temperature of the material is reduced to be very low, the influence of oxidation and thermal decomposition of the material is also reduced to be minimum, and the thin film evaporator or short path evaporator is very effective for separating extremely unstable heat-sensitive materials. However, the thin film evaporator or short path molecular distillation apparatus is not suitable for the mass production of adiponitrile because of its high investment, high operation cost, high energy consumption and low production capacity. There are numerous patents which disclose that the economics and catalyst stability of the process for recovering the catalyst by distillation are to be improved.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: provides a double-falling-film evaporation efficient rectifying tower capable of separating and recovering a nickel catalyst system through distillation, and aims to solve the problems of general rectifying effect, low energy consumption and low production capacity of the conventional rectifying tower at present.
The technical scheme adopted by the invention is as follows: the utility model provides a two falling liquid film formula evaporation rectifying column systems, including rectifying column, first falling liquid film reboiler and second falling liquid film reboiler, the rectifying column includes tower cauldron, stripping section, rectifying section and the top of the tower that from the bottom up connected gradually, the top of the tower is provided with a spray thrower, the tower cauldron includes at the bottom of the first tower and the second tower that separate through a baffle, just at the bottom of the first tower with first falling liquid film reboiler links to each other, at the bottom of the second tower with second falling liquid film reboiler links to each other, be provided with the feed inlet on the first falling liquid film reboiler, the top of the tower is provided with the top of the tower discharge gate, one side at the bottom of the first tower is provided with tower cauldron reboiler discharge gate, second falling liquid film one side still is connected at the bottom of a circulating device and first tower.
According to the double-falling-film evaporation rectifying tower system, the first tower bottom and the second tower bottom are arranged and separated, the tower kettle discharge hole is arranged at the first tower bottom, the tower top discharge hole is arranged at the tower top, gas and liquid are separated, two falling-film reboilers are arranged at the same time, treated materials can be thoroughly rectified, raw materials firstly enter the first falling-film reboiler for treatment, then untreated materials enter the second falling-film reboiler again for treatment, different substances are respectively recovered at the first tower bottom and the second tower bottom, and treatment and recycling are facilitated.
Preferably, the outlet of the condenser is connected with a liquid inlet of a reflux ratio controller (not marked in the figure), the reflux ratio controller comprises two liquid outlets, one liquid outlet of the reflux ratio controller is connected with a tower top extraction pump, and the other liquid outlet of the reflux ratio controller is connected with a reflux pump.
Preferably, the circulating device comprises a tower kettle circulating pump, one side of the tower kettle circulating pump is connected with the top of the second falling film reboiler, and the other side of the tower kettle circulating pump is connected with the bottom of the second falling film reboiler. The design of circulating pump can be convenient for the second falling film reboiler to carry out the processing that circulates to the heavier component that flows down from the liquid trap for final rectifying's effect is better.
Preferably, a liquid collector is arranged between the tower kettle and the stripping section, and an opening of the liquid collector is aligned with the bottom of the second tower. The heavier components flowing down from the upper part of the rectifying tower can flow into the bottom part of the second tower through the arrangement of the liquid collector, and are reboiled through the circulating pump and the device body so as to be rectified.
Preferably, the heat exchange area of the first falling film reboiler is larger than that of the second falling film reboiler. The first falling film reboiler can heat most of raw materials, the second falling film reboiler actually plays a role of one reboiler, the temperature requirement of the second falling film reboiler can be reduced due to the fact that the heat exchange area of the first falling film reboiler is large, the application range of the whole rectifying tower system is expanded, and the effects of saving energy and reducing the overall manufacturing cost and the cost of equipment are further achieved.
Preferably, a preheater and a feed distributor (not shown) are arranged on one side of the feed inlet, the preheater is connected with the feed distributor, and the feed distributor is connected with the feed inlet. The feed distributor and the preheater are set, so that the raw materials can be pretreated conveniently, the feed distributor is directly connected with the feed inlet, the product is rectified conveniently, and the production efficiency is improved.
The invention aims to solve another technical problem that: the rectification method of the double falling film evaporation rectification tower system is provided to solve the problems of low efficiency and large loss of the nickel-containing catalyst of the rectification method of the conventional means at present.
The technical scheme adopted by the invention is as follows: the rectification method adopting the double falling film evaporation rectification tower system is used for separating and recovering the nickel catalyst system, and comprises the following steps:
s1, preheating the raw material containing the nickel catalyst, and then injecting the raw material into the feed inlet for rectification reaction; the raw material containing the nickel catalyst comprises a catalyst formed by a mixture of a monodentate ligand and a bidentate ligand and one or more of 3-pentenenitrile, 4-pentenenitrile, 2-methyl-3-butenenitrile, cyclohexane and mononitrile;
s2: after the raw materials are subjected to rectification reaction in a double-falling-film evaporation rectification tower system, the obtained rectification products are respectively recovered at a discharge port of a tower kettle and a discharge port of a tower top, and the rectification is performed.
As a preferable scheme, in the step S2, the rectification reaction specifically includes the following steps:
(a) the raw material enters a first falling film reboiler, part of the raw material is heated, vaporized and ascended, and the other part of the raw material enters the bottom of a first tower and is extracted by a tower kettle extraction pump;
(b) the light components entering the first falling film reboiler are heated, vaporized and then ascend, and then sequentially enter a stripping section and a rectifying section of a rectifying tower (1), gas-liquid mass transfer is realized between the vaporized components and liquid flowing down from the upper part in the rectifying tower in the process, the vaporized components and the liquid enter a condenser from a discharge hole at the top of the tower to be liquefied to form condensate, one part of the condensate flows back to the rectifying tower under the action of a reflux ratio controller, and the other part of the condensate is extracted through a discharge pump at the top of the tower;
(c) the heavier components flow back to the bottom of the second tower, one part of the heavier components flows back to a second falling film reboiler of the rectifying tower under the action of the partial reflux pump through the adjustment of the material discharging proportion distribution, the heavier components enter the rectifying tower to realize gas-liquid mass transfer, and the other part of the heavier components is extracted through a tower kettle extraction pump at one side of the bottom of the second tower to finish the rectification.
Compared with the prior art, the invention has the main advantages that:
(1) in the device and the method, the bottom of the rectifying tower is divided into a first bottom and a second bottom, and a liquid collector is used for providing a downward channel for the reflux liquid to the second bottom for circulating reboiling. The problem of influence of oxidation and thermal decomposition of a catalyst formed by a mixture of a monodentate ligand and a bidentate ligand due to the cyclic reboiling at high temperature is avoided.
(2) The vapor pressure required for the evaporation of the solvent can be met by the reboiler (second falling film reboiler) in the apparatus of the invention. The top pressure of the rectifying tower can be 50-150 mba, the top temperature of the distilling tower is 25-50 ℃, and the extractant can be condensed at the conventional cooling water temperature. The second column bottoms recovered 3PN and 2M3BN, and the first column bottoms recovered catalyst formed from a mixture of monodentate and bidentate ligands.
(3) The residence time of the vapor-liquid phase component in the heating area of the falling film evaporator B in the device is short, so that the occurrence of the deterioration reaction of the material can be reduced.
(4) The device and the method of the invention use the falling film evaporator, can greatly reduce the temperature of the reboiler, not only enlarge the application range of high vacuum rectification, but also play the roles of saving energy and reducing the manufacturing cost of equipment.
(5) The device has the characteristics of large adjustment range of production capacity and flexible and convenient operation, thereby being suitable for large-scale production and application of the process for preparing adiponitrile.
Drawings
FIG. 1 is a schematic front view of the present invention;
the reference numbers in the figures illustrate:
wherein 1, a rectifying tower; 2. a first falling film reboiler; 3. a second falling film reboiler; 4. a condenser; 5. a feed inlet; 6. a first column bottom; 7. a tower top extraction pump; 8. a liquid collector; 9. a circulating pump of the tower kettle; 10. a second tower bottom; 11. a tower kettle extraction pump; 12. a discharge hole at the top of the tower; 13. a discharge port of the tower kettle; 14. A reflux pump; 15. a reflux tank; 16. and a sprayer.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1: this embodiment provides the structure of the present invention:
as shown in fig. 1, fig. 1 is a schematic front structural diagram of the present invention, a main body of the present invention includes a rectifying tower 1, a first falling film reboiler 2, and a second falling film reboiler 3, the rectifying tower 1 includes a tower bottom, a stripping section, a rectifying section, and a tower top connected in sequence from bottom to top, the tower top is provided with a sprayer 16, the tower bottom includes a first tower bottom 6 and a second tower bottom 10 separated by a partition plate, the first tower bottom 6 is connected to the first falling film reboiler 2, the second tower bottom 10 is connected to the second falling film reboiler 3, specifically, the upper surfaces of the first tower bottom 6 and the second tower bottom 10 on the tower bottom are both provided with outlets, and the outlets are respectively connected to the first falling film reboiler 2 and the second falling film reboiler 3;
a tower kettle circulating pump 9 is further arranged on one side of the second falling film reboiler 3, and an inlet and an outlet of the tower kettle circulating pump 9 are respectively connected with the second falling film reboiler 3 and the bottom 10 of the second tower, so that a circulating loop is formed;
the top of the first falling film reboiler 2 is provided with a feed inlet 5, one side of the feed inlet 5 is provided with a preheater and a feed distributor, the preheater is connected with the feed distributor, and the feed distributor is connected with the feed inlet 5, so that raw materials can be preheated and distributed during feeding;
a tower kettle discharge port 13 is arranged on the first tower bottom 6, and a tower kettle extraction pump 11 is arranged on one side of the tower kettle discharge port 13;
the tower top is provided with a tower top discharge hole 12, the tower top discharge hole 12 is also connected with an inlet of a condenser 4, an outlet of the condenser 4 is connected with a reflux tank 15, and the reflux tank 15 is connected with a tower top extraction pump 7;
the rectifying tower 1 is also provided with a liquid collector 8 at the lower part of the stripping section, and the opening of the liquid collector 8 is aligned with the bottom 10 of the second tower.
Example 2: this example provides a rectification method of the apparatus of the invention:
the method comprises the following steps:
providing a rectification method adopting the double falling film type evaporation rectification tower 1 system, wherein the rectification method is used for separating and recovering a nickel catalyst system and comprises the following steps:
s1, preheating the raw material containing the nickel catalyst, and then injecting the raw material into a feed inlet 5(5) for rectification reaction; the raw material containing the nickel catalyst comprises a catalyst formed by a mixture of a monodentate ligand and a bidentate ligand and one or more of 3-pentenenitrile, 4-pentenenitrile, 2-methyl-3-butenenitrile, cyclohexane and mononitrile;
s2: after the raw materials are subjected to rectification reaction in a double-falling-film evaporation rectification tower 1 system, the obtained rectification products are respectively recovered at a tower kettle discharge port 13 and a tower top discharge port 12, and the rectification is performed.
In the step S2, the rectification reaction specifically includes the following steps:
(a) the raw material enters a first falling film reboiler 2, part of the raw material is heated, vaporized and ascended, and the other part of the raw material enters a first tower bottom 6 and is extracted through a tower kettle extraction pump 11;
(b) the light components entering the first falling film reboiler 2 are heated, vaporized and then ascend, and then sequentially enter a stripping section and a rectifying section of a rectifying tower 1(1), gas-liquid mass transfer is realized between the vaporized components and liquid flowing down from the upper part in the rectifying tower 1 in the process, the vaporized components and the liquid enter a condenser 4 from a discharge port 12 at the top of the tower to be liquefied to form condensate, one part of the condensate flows back to the rectifying tower 1 under the action of a reflux ratio controller, and the other part of the condensate is extracted by a recovery pump 7 at the top of the tower;
(c) the heavier components flow back to the second tower bottom 10, one part of the heavier components flows back to the second falling film reboiler 3 of the rectifying tower 1 under the action of the partial reflux pump 14 through the adjustment of the material discharge proportion distribution, the heavier components enter the rectifying tower 1 to realize gas-liquid mass transfer, and the other part of the heavier components is extracted through a tower kettle extraction pump 11 on one side of the second tower bottom 10 to finish the rectification.
Specific embodiments including specific data are provided below:
the starting material employed in this example originates from the stage of conversion of these mononitriles to dinitriles by reaction with HCN, the nickel catalyst (organometallic complex and organophosphorus ligand) being extracted in the medium of the dinitrile by liquid/liquid extraction using an extraction solvent which is cyclohexane. Distillation is then carried out in order to separate the extraction solvent and to recycle the organonickel catalyst (organometallic complex and ligand) thus recovered. The extract phase solvent contained 83% cyclohexane and 4% mononitriles (3PN and 4PN), and in addition, the catalyst component nickel and ligand mixture (the percentages are by weight, in molar ratios, Ni ═ 1.0% ligand a/Ni ═ 12).
The rectification method of the double-falling-film evaporation rectification tower 1 system of the embodiment specifically comprises the following steps:
s1: the extractive phase solvent mixture to be treated is sent to a preheater through a feeding metering pump at the flow rate of 2.5L, and then the preheated raw material enters a first falling film reboiler 2 through a feeding distributor in a uniformly distributed manner (the heat exchange area of the first falling film reboiler 2 in the embodiment is 2m2), and then enters a stripping section of a rectifying tower 1, and the inlet temperature of the stripping section is set to be 82 ℃.
S2: the gas treated by the first falling film reboiler 2 enters a stripping section, vaporized cyclohexane and part of mononitrile gas rise, the other part of mononitrile and the mixture containing the catalyst components, namely nickel and ligand, descend to the bottom 6 of the first tower, and finally the catalyst is recovered by driving of a tower bottom extraction pump 11 and leaves the tower bottom through a tower bottom discharge hole 13.
And finally, sampling, detecting and analyzing the raw material extracted from the discharge hole 13 of the tower bottom, wherein the raw material contains 27% of ligand mixture, 1% of Ni, and 62% of 3PN and 4PN in total, the cyclohexane content is less than 200ppm, and the balance is dinitrile.
The liquid phase components in the rectifying tower 1 are finally recovered from the cyclohexane and the mononitrile to the bottom 10 part of the second tower through the liquid collector 8, and are refluxed to the second falling film reboiler 3 (the heat exchange area is 1m2 in the embodiment) again under the action of the tower kettle circulating pump 9, and the liquid phase components rise after being heated and vaporized and sequentially enter the stripping section and the rectifying section of the rectifying tower 1 through high vacuum provided by the vacuum pump to realize gas-liquid mass transfer with the refluxed liquid flowing down from the top.
Gas phase components in the rectifying tower 1 finally enter a condenser 4 from a discharge hole 12 at the top of the tower at the absolute pressure of 110 millibar and the top temperature of 37 ℃, are converted into light components by a condenser and are liquefied under the cooling action of condensed water, the reflux ratio of a reflux ratio controller is set to be 2, the liquid part of the light components is collected into a reflux tank 15 and is extracted by a extraction pump 7 at the top of the tower, and finally, sampling detection analysis is carried out to respectively collect liquid products of cyclohexane with the mass percentage purity of more than 98%.
In this example, the height of the rectification column 1 is 3000mm, the internal diameter is 300mm, and the wall temperature of the second falling film reboiler 3 is less than 140 ℃. The rectification column 1 was operated continuously for 72 hours, and the loss of complexed nickel was determined to be 0 by chromatographic analysis.
It follows that, with the above-described rectification apparatus and rectification conditions, in particular the control of the maximum temperature of the walls of the falling-film evaporator, it is possible to limit or even eliminate the precipitation of metal elements during the separation or distillation phase, since higher temperatures decompose the catalyst.
The invention overcomes the defects of the prior art and provides a double falling-film evaporation efficient rectifying tower 1 for separating and recovering a nickel catalyst system through distillation. The apparatus is not restricted by the height of the rectifying column 1, and the catalyst is stably recovered from the extract without any heat loss. The method can greatly reduce energy consumption. The double falling film evaporation pressure of the tower kettle can reduce the possibility of deterioration of some heat-sensitive substances of 50-150 mba caused by overlong residence time in a high-temperature area in the tower, and can meet the vapor pressure required by an evaporation solvent. By implementing the invention, the pressure at the top of the vacuum distillation tower 1 can be reduced to that at the top of the distillation tower, the extractant is condensed at the conventional cooling water temperature of 25-50 ℃. The bottom a of the vacuum rectification column 1 recovers 3PN and 2M3BN and the bottom B of the column recovers the catalyst formed by the mixture of monodentate ligand and bidentate ligand.
The foregoing has described preferred embodiments of the present invention and is not to be construed as limiting the claims. The present invention is not limited to the above embodiments, and the specific structure thereof is allowed to vary, and various changes made within the scope of the independent claims of the present invention are within the scope of the present invention.
Claims (10)
1. A double falling film type evaporation rectifying tower system is characterized by comprising a rectifying tower (1), a first falling film reboiler (2) and a second falling film reboiler (3), the rectifying tower (1) comprises a tower kettle, a stripping section, a rectifying section and a tower top which are connected in sequence from bottom to top, the tower top is provided with a sprayer (16), the tower kettle comprises a first tower bottom (6) and a second tower bottom (10) which are separated by a partition plate, and the first bottom (6) is connected to the first falling film reboiler (2) and the second bottom (10) is connected to the second falling film reboiler (3), a feed inlet (5) is arranged on the first falling film reboiler (2), a discharge outlet (12) is arranged at the top of the tower, a tower kettle discharge hole (13) is formed in one side of the first tower bottom (6), and one side of the second falling film reboiler (3) is connected with the first tower bottom (6) through a circulating device.
2. The dual falling film evaporative rectification column system as claimed in claim 1, wherein the top discharge port (12) is further connected to an inlet of a condenser (4), an outlet of the condenser (4) is connected to a reflux drum (15), and the reflux drum (15) is connected to a top take-off pump (7).
3. The dual falling film evaporative rectification column system as set forth in claim 2 wherein the outlet of the condenser (4) is connected to an inlet of a reflux ratio controller and the reflux ratio controller comprises two outlets, one of the outlets of the reflux ratio controller being connected to an overhead take-off pump (7) and the other outlet of the reflux ratio controller being connected to a reflux pump (14).
4. The dual falling film evaporative rectification column system as set forth in claim 1, wherein the circulating means comprises a column bottom circulating pump (9), and the column bottom circulating pump (9) is connected to the top of the second falling film reboiler (3) at one side and the column bottom circulating pump (9) is connected to the second column bottom (10) at the other side.
5. The dual falling film evaporative rectifier system as claimed in claim 1, wherein a liquid trap (8) is disposed between the bottom and the stripping section, and the opening of said liquid trap (8) is aligned with said second bottom (10).
6. The dual falling film evaporative rectification column system as set forth in claim 1 wherein the top of the column is further connected to a reflux pump (14); and a tower kettle extraction pump (11) is arranged on one side of the tower kettle discharge port (13).
7. The dual falling film evaporative rectifier system of claim 1, wherein the first falling film reboiler (2) has a larger heat exchange area than the second falling film reboiler (3).
8. Double falling film evaporation and rectification column system according to claim 1, characterized in that a preheater and a feed distributor are arranged on one side of the feed opening (5) and are connected with the feed distributor, which is connected with the feed opening (5).
9. A rectification method of a double falling film evaporation rectification column system according to any one of claims 1 to 8, wherein the rectification method is used for separating and recovering a nickel catalyst system and comprises the following steps:
s1, preheating the raw material containing the nickel catalyst, and then injecting the raw material into a feed inlet (5) for rectification reaction; the raw material containing the nickel catalyst comprises a catalyst formed by a mixture of a monodentate ligand and a bidentate ligand and one or more of 3-pentenenitrile, 4-pentenenitrile, 2-methyl-3-butenenitrile, cyclohexane and mononitrile;
s2: after the raw materials are subjected to rectification reaction in a double-falling-film evaporation rectification tower system, the obtained rectification products are respectively recovered at a tower kettle discharge port (13) and a tower top discharge port (12), and the rectification is completed.
10. The method for rectifying a dual falling film evaporation and rectification column system according to claim 9, wherein in the step S2, the rectification reaction specifically comprises the following steps:
(a) the raw material enters a first falling film reboiler, part of the raw material is heated, vaporized and ascended, and the other part of the raw material enters the bottom of a first tower and is extracted by a tower kettle extraction pump (11);
(b) the light components entering the first falling film reboiler (2) in the step (a) are heated and vaporized, then ascend, and then sequentially enter a stripping section and a rectifying section of the rectifying tower (1), gas-liquid mass transfer is realized between the vaporized components and liquid flowing down from the upper part in the rectifying tower (1) in the process, the vaporized components enter a condenser (4) from a discharge hole (12) at the top of the tower to be liquefied to form condensate, one part of the condensate flows back to the rectifying tower (1) under the action of a reflux ratio controller, and the other part of the condensate is extracted through a top extraction pump (7);
(c) the heavier components flow back to the second tower bottom (10), one part flows back to the second falling film reboiler (3) of the rectifying tower (1) under the action of the component reflux pump (14) through the adjustment of the material discharging proportion distribution, enters the rectifying tower (1) to realize gas-liquid mass transfer, and the other part is extracted through the tower kettle extraction pump (11) to finish the rectification.
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Cited By (1)
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