CN110003054B - Water removal system and water removal method of isocyanate production device by phosgenation - Google Patents
Water removal system and water removal method of isocyanate production device by phosgenation Download PDFInfo
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- CN110003054B CN110003054B CN201910237026.0A CN201910237026A CN110003054B CN 110003054 B CN110003054 B CN 110003054B CN 201910237026 A CN201910237026 A CN 201910237026A CN 110003054 B CN110003054 B CN 110003054B
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- dephosgene
- kettle
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 84
- 238000000034 method Methods 0.000 title claims abstract description 55
- 239000012948 isocyanate Substances 0.000 title claims abstract description 33
- 150000002513 isocyanates Chemical class 0.000 title claims abstract description 33
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 22
- 239000002904 solvent Substances 0.000 claims abstract description 347
- 238000007670 refining Methods 0.000 claims description 119
- 239000007791 liquid phase Substances 0.000 claims description 78
- 238000010521 absorption reaction Methods 0.000 claims description 58
- 239000012071 phase Substances 0.000 claims description 57
- 238000000926 separation method Methods 0.000 claims description 56
- 239000007788 liquid Substances 0.000 claims description 55
- MVPPADPHJFYWMZ-UHFFFAOYSA-N chlorobenzene Chemical compound ClC1=CC=CC=C1 MVPPADPHJFYWMZ-UHFFFAOYSA-N 0.000 claims description 38
- 238000003860 storage Methods 0.000 claims description 28
- 239000006096 absorbing agent Substances 0.000 claims description 18
- YGYAWVDWMABLBF-UHFFFAOYSA-N Phosgene Chemical compound ClC(Cl)=O YGYAWVDWMABLBF-UHFFFAOYSA-N 0.000 claims description 17
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 9
- RFFLAFLAYFXFSW-UHFFFAOYSA-N 1,2-dichlorobenzene Chemical compound ClC1=CC=CC=C1Cl RFFLAFLAYFXFSW-UHFFFAOYSA-N 0.000 claims description 6
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 6
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims description 2
- JLVWYWVLMFVCDI-UHFFFAOYSA-N diethyl benzene-1,3-dicarboxylate Chemical compound CCOC(=O)C1=CC=CC(C(=O)OCC)=C1 JLVWYWVLMFVCDI-UHFFFAOYSA-N 0.000 claims description 2
- 239000008096 xylene Substances 0.000 claims description 2
- 230000007797 corrosion Effects 0.000 abstract description 3
- 238000005260 corrosion Methods 0.000 abstract description 3
- 238000005516 engineering process Methods 0.000 abstract description 3
- 238000005265 energy consumption Methods 0.000 abstract description 2
- 239000002253 acid Substances 0.000 abstract 1
- 239000000463 material Substances 0.000 abstract 1
- 238000007086 side reaction Methods 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 56
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 238000010926 purge Methods 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 150000001412 amines Chemical class 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- RRAMGCGOFNQTLD-UHFFFAOYSA-N hexamethylene diisocyanate Chemical compound O=C=NCCCCCCN=C=O RRAMGCGOFNQTLD-UHFFFAOYSA-N 0.000 description 3
- 238000000859 sublimation Methods 0.000 description 3
- 230000008022 sublimation Effects 0.000 description 3
- UPMLOUAZCHDJJD-UHFFFAOYSA-N 4,4'-Diphenylmethane Diisocyanate Chemical compound C1=CC(N=C=O)=CC=C1CC1=CC=C(N=C=O)C=C1 UPMLOUAZCHDJJD-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 239000005057 Hexamethylene diisocyanate Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 2
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- DVKJHBMWWAPEIU-UHFFFAOYSA-N toluene 2,4-diisocyanate Chemical compound CC1=CC=C(N=C=O)C=C1N=C=O DVKJHBMWWAPEIU-UHFFFAOYSA-N 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- KXBFLNPZHXDQLV-UHFFFAOYSA-N [cyclohexyl(diisocyanato)methyl]cyclohexane Chemical compound C1CCCCC1C(N=C=O)(N=C=O)C1CCCCC1 KXBFLNPZHXDQLV-UHFFFAOYSA-N 0.000 description 1
- -1 acrylic ester Chemical class 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000003125 aqueous solvent Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- NHYCGSASNAIGLD-UHFFFAOYSA-N chlorine monoxide Inorganic materials Cl[O] NHYCGSASNAIGLD-UHFFFAOYSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- IQPQWNKOIGAROB-UHFFFAOYSA-N isocyanate group Chemical group [N-]=C=O IQPQWNKOIGAROB-UHFFFAOYSA-N 0.000 description 1
- NIMLQBUJDJZYEJ-UHFFFAOYSA-N isophorone diisocyanate Chemical compound CC1(C)CC(N=C=O)CC(C)(CN=C=O)C1 NIMLQBUJDJZYEJ-UHFFFAOYSA-N 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 150000003141 primary amines Chemical class 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C263/00—Preparation of derivatives of isocyanic acid
- C07C263/10—Preparation of derivatives of isocyanic acid by reaction of amines with carbonyl halides, e.g. with phosgene
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C263/00—Preparation of derivatives of isocyanic acid
- C07C263/18—Separation; Purification; Stabilisation; Use of additives
- C07C263/20—Separation; Purification
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2601/00—Systems containing only non-condensed rings
- C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
- C07C2601/14—The ring being saturated
Abstract
The invention discloses a water removal system and a water removal method of an isocyanate production device by phosgenation. In the initial stage of starting the device for producing isocyanate by phosgenation, the solvent is used to run in a water removal system, the residual moisture in the system is dissolved in the solvent, the solvent is recycled, and the moisture is enriched and discharged. The technology can effectively reduce the water content in the system, reduce the corrosion of the acid environment formed by the water content after the material is fed to the equipment, and reduce the side reaction of the water content and isocyanate products. Meanwhile, the energy consumption in the water removal process can be effectively reduced, and the running water removal time of the solvent is shortened. The water removal system and the water removal method are simple in flow, convenient to operate, efficient and energy-saving.
Description
Technical Field
The invention belongs to the field of chemical technology, relates to a production device water removal system and a water removal method, and in particular relates to a water removal system and a water removal method of a phosgenation isocyanate production device.
Technical Field
Isocyanate is widely applied to industries such as household appliances, automobiles, buildings, shoe industries, furniture, adhesives and the like. The existing industrialized isocyanate production mainly adopts a primary amine phosgenation method to produce: firstly reacting chlorine and carbon monoxide to generate phosgene, secondly reacting phosgene and organic amine in a solvent to generate isocyanate and hydrogen chloride, and separating the isocyanate and the hydrogen chloride from the solvent again.
The reactor, storage tank, tower and the like of the phosgenation isocyanate production device work at high temperature and high pressure, and risks such as poisoning accidents and fire explosion accidents are caused by equipment corrosion, and the existence of moisture in the system is the most main cause of equipment corrosion.
The isocyanate structure contains unsaturated bond, so that the isocyanate has high activity, and reacts with water to generate amine and carbon dioxide, and the amine further reacts with isocyanate to generate urea, so that the isocyanate product is lost and the quality is reduced.
The isocyanate production device by phosgenation is not easy to introduce moisture during normal production. The moisture is mainly introduced into the system after the vehicle is stopped and during the process of equipment opening and maintenance, etc. In order to ensure that the water content of the device can reach a reasonable range when phosgene enters the device and meet the production requirement, the device for producing isocyanate by phosgenation must adopt a method to reduce the water content in the system at the initial stage of starting.
The patent CN104311454A discloses a dewatering device for acrylic ester chemical products, the patent uses a sublimation tower, a condenser and an oil-water separation tank to remove byproduct water, the patent does not describe an oil-water layering effect and a drainage method, drainage of a whole set of device system is not described, the sublimation tower adopts a filler tower, toluene solution is required to be conveyed back to the sublimation tower by a pump to wash the filler, and energy is wasted.
The technical literature has not been found to disclose an isocyanate device water removal method, so that aiming at the problems of the existing isocyanate device water removal in the phosgenation production, a high-efficiency isocyanate device water removal technology in the phosgenation production needs to be developed.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a water removal system and a water removal method of an isocyanate production device by phosgenation. At the initial stage of starting the device for producing isocyanate by phosgenation, the solvent is used to run in a water removal system, the residual moisture in the system is dissolved in the solvent, the solvent is recycled, and the moisture is enriched and discharged. The water in the system is effectively removed, the production requirement is met, the efficiency is high, the energy is saved, more production time is strived for the device, and the operation rate of the device is improved.
In order to achieve the above purpose, the invention adopts the following technical scheme:
A water removal system for a phosgenation isocyanate production apparatus comprising: an absorption tower 1, a phosgenation reactor 2, a tower kettle reboiler 10 of the phosgenation reactor, a dephosgene tower 3, a dephosgene tower kettle reboiler 11, a solvent removal tower 4, a solvent removal tower kettle reboiler 12, a solvent removal tower top cooler 15, a solvent removal tower top gas-liquid separation tank 8, a crude solvent buffer tank 6, a solvent refining tower 5, a solvent refining tower kettle reboiler 13, a dephosgene tower, a solvent refining tower top cooler 14, a dephosgene tower, a solvent refining tower top gas-liquid separation tank 9 and a solvent storage tank 7;
The upper part of the absorption tower 1 is provided with an absorption tower solvent feeding pipe 16, the bottom of the tower kettle of the absorption tower 1 is connected with a crude solvent buffer tank 6 through a liquid phase pipeline 20, the crude solvent buffer tank 6 is connected with the upper part of a solvent refining tower 5, the top of the solvent refining tower 5 is connected with a dephosgene tower and a solvent refining tower top cooler 14 through a gas phase pipeline,
The bottom of the tower kettle of the solvent refining tower 5 is connected with a solvent storage tank 7 through a liquid phase pipeline;
The upper part of the phosgenation reactor 2 is provided with a solvent feed pipe 17 of the phosgenation reactor, and the top of the phosgenation reactor 2 is connected with the tower kettle of the absorption tower 1 through a gas phase pipeline;
The bottom of the tower kettle of the phosgenation reactor 2 is connected with the middle part of a dephosgene tower 3 through a liquid phase pipeline, the top of the dephosgene tower 3 is connected with a dephosgene tower and a solvent refining tower top cooler 14 through a gas phase pipeline, the bottom of the tower kettle of the dephosgene tower 3 is connected with the upper part of a solvent removal tower 4 through a liquid phase pipeline, the top of the solvent removal tower 4 is connected with a solvent removal tower top cooler 15 through a gas phase pipeline, the solvent removal tower top cooler 15 is connected with a solvent removal tower top gas-liquid separation tank 8, the bottom of the solvent removal tower top gas-liquid separation tank 8 is connected with a solvent storage tank 7 through a liquid phase pipeline 21, and the top of the solvent removal tower top gas-liquid separation tank 8 is connected with the tower kettle of the absorption tower 1 through a gas phase pipeline;
The top part of the dephosgene tower and the solvent refining tower top gas-liquid separation tank 9 is connected with the tower kettle of the absorption tower 1 through a gas phase pipeline, and a drain pipe 19 is arranged on the top part of the dephosgene tower and the solvent refining tower top gas-liquid separation tank 9;
The top of the absorption tower 1 is provided with a tail gas discharge pipe 18.
The column bottoms of the phosgenation reactor 2, the dephosgene column 3, the solvent removal column 4 and the solvent refining column 5 are respectively provided with a reboiler for heating the corresponding column bottom liquid phase and recycling the liquid phase to the column bottom. Wherein, the bottom of the phosgenation reactor 2 is provided with a tower kettle reboiler 10 of the phosgenation reactor. The bottom of the dephosgene tower 3 is provided with a dephosgene tower kettle reboiler 11. The bottom of the solvent removal tower 4 is provided with a solvent removal tower kettle reboiler 12. The bottom of the solvent refining tower 5 is provided with a solvent refining tower kettle reboiler 13.
Preferably, the solvent storage tank 7 is connected with the absorption tower solvent feed pipe 16 and/or the phosgenation reactor solvent feed pipe 17 through pipelines, and a cooler is optionally arranged on the pipeline connecting the solvent storage tank 7 with the absorption tower solvent feed pipe 16 and/or the phosgenation reactor solvent feed pipe 17.
A method of removing water using the system of the present invention comprises the steps of;
Adding solvent into the absorption tower 1 from the absorption tower solvent feed pipe 16, and leading the solvent to the crude solvent buffer tank 6 from the bottom of the tower kettle of the absorption tower 1; the solvent of the crude solvent buffer tank 6 enters the upper part of the solvent refining tower 5, and the top gas phase of the solvent refining tower 5 enters the gas-liquid separation tank 9 of the dephosgene tower and the solvent refining tower after being condensed by the dephosgene tower and the solvent refining tower top cooler 14; the liquid phase produced from the bottom of the tower kettle of the solvent refining tower 5 enters a solvent storage tank 7;
adding solvent into the phosgenation reactor 2 from a solvent feed pipe 17 of the phosgenation reactor, enabling a gas phase at the top of the phosgenation reactor 2 to enter a tower kettle of the absorption tower 1, and enabling a liquid phase at the bottom of the tower kettle of the phosgenation reactor 2 to enter the middle part of the dephosgene tower 3;
The gas phase at the top of the dephosgene tower 3 is condensed by a dephosgene tower and a solvent refining tower top cooler 14 and then enters a gas-liquid separation tank 9 at the top of the dephosgene tower and the solvent refining tower;
The gas phase and the liquid phase are obtained in a gas-liquid separation tank 9 at the top of the dephosgene tower and the solvent refining tower, the obtained gas phase enters the tower kettle of the absorption tower 1, the obtained liquid phase enters the upper part of the solvent refining tower 5, water is enriched and layered in the gas-liquid separation tank 9 at the top of the dephosgene tower and the solvent refining tower, and the water is discharged through a drain pipe 19;
The liquid phase produced from the bottom of the tower kettle of the dephosgene tower 3 enters the upper part of the solvent removal tower 4, the top gas phase of the solvent removal tower 4 is condensed by a solvent removal tower top cooler 15 and then enters a solvent removal tower top gas-liquid separation tank 8 to obtain a gas phase and a liquid phase, the obtained gas phase enters the tower kettle of the absorption tower 1, and the obtained liquid phase enters a solvent storage tank 7;
The exhaust gas is discharged from the exhaust gas discharge pipe 18.
The solvent in the solvent tank 7 according to the invention may be supplied as solvent to the absorber solvent feed line 16 and/or to the phosgenation reactor solvent feed line 17.
In the process according to the invention, the solvent is selected from one or more of diethyl isophthalate, benzene, toluene, xylene, chlorobenzene and o-dichlorobenzene, preferably chlorobenzene and o-dichlorobenzene, more preferably chlorobenzene.
In the process according to the invention, the moisture content of the solvent is from 0 to 0.400% by weight, preferably from 0 to 0.0300% by weight.
In the process according to the invention, the temperature of the solvent is between 10 and 60 ℃, preferably between 20 and 50 ℃, more preferably between 30 and 40 ℃.
In the process according to the invention, the gauge pressure of the absorber 1 is from 100 to 150KPa, preferably from 100 to 130KPa, more preferably from 100 to 110KPa.
In the process according to the invention, the gauge pressure of the phosgenation reactor 2 is from 100 to 150KPa, preferably from 100 to 130KPa, more preferably from 100 to 110KPa; the column bottom temperature of the phosgenation reactor 2 is 130 to 170 ℃, preferably 140 to 160 ℃, more preferably 150 to 160 ℃.
In the process according to the invention, the gauge pressure of the dephosgene column 3 is from 100 to 150KPa, preferably from 100 to 130KPa, more preferably from 100 to 110KPa; the temperature of the column bottom of the dephosgene column 3 is 130-170 ℃, preferably 140-160 ℃, more preferably 150-160 ℃.
In the process of the present invention, the gauge pressure of the solvent removal column 4 is 20 to 80KPa, preferably 30 to 70KPa, more preferably 40 to 60KPa; the temperature of the bottom of the solvent removal column 4 is 100 to 150 ℃, preferably 110 to 140 ℃, more preferably 120 to 130 ℃.
In the method of the present invention, the gauge pressure of the solvent refining column 5 is 100 to 150KPa, preferably 100 to 130KPa, more preferably 100 to 110KPa; the temperature of the column bottom of the solvent refining column 5 is 130 to 180 ℃, preferably 140 to 170 ℃, more preferably 150 to 160 ℃.
In the process according to the invention, the condensed liquid phase temperature in the dephosgene column and in the solvent refining overhead cooler 14 is 50-100 ℃, preferably 60-90 ℃, more preferably 70-80 ℃.
In the process according to the invention, the condensed liquid phase temperature in the solvent removal overhead cooler 15 is 50-100 ℃, preferably 60-90 ℃, more preferably 70-80 ℃.
The absorption column, phosgenation reactor, dephosgene column, solvent removal column, solvent refining column described in the present invention may be any apparatus known in the art.
Preferably, the absorption tower is a packed tower; the phosgenation reactor is a plate tower; the dephosgene tower is a plate tower; the solvent removal tower is a plate tower; the solvent refining tower is a plate tower.
The water removal system and the water removal method of the present invention are suitable for use in a reaction apparatus for preparing isocyanate by phosgenation, including but not limited to Toluene Diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene Diisocyanate (HDI), and the like.
In the process of producing isocyanate by phosgenation, an absorption tower 1 is used for absorbing phosgene in the exhaust gas of a phosgenation reactor 2; the phosgenation reactor 2 is used for carrying out phosgenation reaction; the dephosgene tower 3 is used for removing phosgene in the mixed solution after the phosgenation reaction; the solvent removal tower 4 is used for removing the solvent in the mixed solution after the phosgenation reaction; the solvent refining tower 5 is used for refining the solvent containing impurities; the crude solvent buffer tank 6 is used for removing solvent containing impurities from the system; the solvent storage tank 7 is used for storing the solvent which is qualified after refining.
The water removal methods described herein may be used in combination with other water removal methods known in the art, including but not limited to nitrogen purging. As a preferable scheme, nitrogen purging can be performed first, and then the water removal method disclosed by the invention is adopted for further water removal.
In the device for producing isocyanate by phosgenation treated by the water removal method, the water content can reach below 100ppm, and the water content in the solvent in the crude solvent buffer tank 6 represents the water content in the device.
The water removal system and the method are particularly suitable for removing water introduced into the system in the processes of opening and overhauling the device for producing isocyanate by phosgenation and the like, and improve the starting efficiency. In the invention, the solvent operation and water removal are quick and efficient, particularly in the solvent operation process route selection, the principle that the upstream solvent of the system is conveyed to the downstream solvent refining tower in the shortest route, the downstream aqueous solvent is prevented from returning to the upstream system, and the water removal qualified solvent is directly conveyed to the qualified solvent storage tank is adopted, so that the process route is greatly simplified, the solvent operation time is shortened, and the efficiency is improved.
Drawings
FIG. 1 is a schematic diagram of a water removal system of the present invention;
FIG. 2 is a schematic diagram of the water removal system of comparative example 1;
1. an absorption tower; 2. a phosgenation reactor; 3. a dephosgene tower; 4. a solvent removal column; 5. a solvent refining tower; 6. a crude solvent buffer tank; 7, a solvent storage tank; 8.a solvent removal tower top gas-liquid separation tank; 9. a gas-liquid separation tank at the top of the dephosgene tower and the solvent refining tower; 10. a tower kettle reboiler of the phosgenation reactor; 11. a reboiler of the phosgene removal tower kettle; 12. a reboiler of the solvent removal tower kettle; 13. a reboiler of the solvent refining tower kettle; 14. a dephosgene tower and a solvent refining tower top cooler; 15. a solvent removal overhead cooler; 16. a solvent feed pipe of the absorber; 17. a solvent feed line to the phosgenation reactor; 18. a tail gas discharge pipe; 19. a drain pipe; 20. a liquid phase pipeline connecting the bottom of the tower kettle of the absorption tower 1 and the crude solvent buffer tank 6; 21. a liquid phase pipeline connecting the solvent removal tower top gas-liquid separation tank 8 and the solvent storage tank 7; 22. a liquid phase pipeline connecting the bottom of the tower kettle of the absorption tower 1 and the tower kettle of the phosgenation reactor 2; 23. a liquid phase pipeline connecting the solvent removal tower top gas-liquid separation tank 8 and the crude solvent buffer tank 6.
Detailed Description
The following examples will further illustrate the method provided by the present invention, but the invention is not limited to the examples listed and should also include any other known modifications within the scope of the claims.
In the present invention, it should be understood that the positional relationship indicated by the terms "upper", "top", "bottom", "middle", etc. are based on the positional relationship shown in the drawings, and are merely for convenience of description and simplification of the description, and are not indicative or implying that the apparatus or element referred to must have a specific position, be constructed and operated in a specific position, and thus should not be construed as limiting the present invention.
The moisture content of the solvent was measured using a karl fischer moisture meter.
Example 1
A water removal system for an isocyanate production plant by phosgenation as shown in figure 1, comprising: an absorption tower 1, a phosgenation reactor 2, a tower kettle reboiler 10 of the phosgenation reactor, a dephosgene tower 3, a dephosgene tower kettle reboiler 11, a solvent removal tower 4, a solvent removal tower kettle reboiler 12, a solvent removal tower top cooler 15, a solvent removal tower top gas-liquid separation tank 8, a crude solvent buffer tank 6, a solvent refining tower 5, a solvent refining tower kettle reboiler 13, a dephosgene tower, a solvent refining tower top cooler 14, a dephosgene tower, a solvent refining tower top gas-liquid separation tank 9 and a solvent storage tank 7;
The upper part of the absorption tower 1 is provided with an absorption tower solvent feeding pipe 16, the bottom of the tower kettle of the absorption tower 1 is connected with a crude solvent buffer tank 6 through a liquid phase pipeline 20, the crude solvent buffer tank 6 is connected with the upper part of a solvent refining tower 5, the top of the solvent refining tower 5 is connected with a dephosgene tower and a solvent refining tower top cooler 14 through a gas phase pipeline,
The bottom of the tower kettle of the solvent refining tower 5 is connected with a solvent storage tank 7 through a liquid phase pipeline;
The upper part of the phosgenation reactor 2 is provided with a solvent feed pipe 17 of the phosgenation reactor, and the top of the phosgenation reactor 2 is connected with the tower kettle of the absorption tower 1 through a gas phase pipeline;
The bottom of the tower kettle of the phosgenation reactor 2 is connected with the middle part of a dephosgene tower 3 through a liquid phase pipeline, the top of the dephosgene tower 3 is connected with a dephosgene tower and a solvent refining tower top cooler 14 through a gas phase pipeline, the bottom of the tower kettle of the dephosgene tower 3 is connected with the upper part of a solvent removal tower 4 through a liquid phase pipeline, the top of the solvent removal tower 4 is connected with a solvent removal tower top cooler 15 through a gas phase pipeline, the solvent removal tower top cooler 15 is connected with a solvent removal tower top gas-liquid separation tank 8, the bottom of the solvent removal tower top gas-liquid separation tank 8 is connected with a solvent storage tank 7 through a liquid phase pipeline 21, and the top of the solvent removal tower top gas-liquid separation tank 8 is connected with the tower kettle of the absorption tower 1 through a gas phase pipeline;
The top part of the dephosgene tower and the solvent refining tower top gas-liquid separation tank 9 is connected with the tower kettle of the absorption tower 1 through a gas phase pipeline, and a drain pipe 19 is arranged on the top part of the dephosgene tower and the solvent refining tower top gas-liquid separation tank 9;
The top of the absorption tower 1 is provided with a tail gas discharge pipe 18.
And the bottoms of the phosgenation reactor 2, the dephosgene tower 3, the solvent removal tower 4 and the solvent refining tower 5 are respectively provided with reboilers for recycling corresponding tower bottom liquid phases back to the tower bottom. Wherein, the bottom of the phosgenation reactor 2 is provided with a tower kettle reboiler 10 of the phosgenation reactor. The bottom of the dephosgene tower 3 is provided with a dephosgene tower kettle reboiler 11. The bottom of the solvent removal tower 4 is provided with a solvent removal tower kettle reboiler 12. The bottom of the solvent refining tower 5 is provided with a solvent refining tower kettle reboiler 13.
The main device capacity parameters are as follows:
Absorption tower 1: the size phi is 1800mm multiplied by 30225mm, and the capacity of the tower kettle is 9m 3;
phosgenation reactor 2: the size phi is 5200mm multiplied by 38350mm, and the capacity of the tower kettle is 70m 3;
and (3) a dephosgene tower: the size phi is 2200mm multiplied by 25650mm, and the capacity of the tower kettle is 10m 3;
Solvent removal column 4: the size phi is 5200mm multiplied by 15350mm, and the capacity of the tower kettle is 17m 3;
solvent refining column 5: the size phi is 3000mm multiplied by 26080mm, and the capacity of the tower kettle is 12m 3;
crude solvent buffer tank 6: the dimension phi is 2500mm multiplied by 5590mm, and the capacity is 24m 3;
Solvent storage tank 7: the dimension phi is 3500mm multiplied by 8013mm, and the capacity is 70m 3.
Example 2
This example is a water removal process for a phosgenation isocyanate production plant using the water removal system of example 1. Before solvent feeding, the system was dried to a dew point of-40 ℃ using nitrogen purge at normal pressure.
The solvent was chlorobenzene, the water content in the chlorobenzene was 0.0125wt%, based on the mass of the solvent, the temperature was 30 ℃.
The absorption tower 1 is a packed tower, and the top operating pressure is 100KPa.
The overhead operating pressure of the phosgenation reactor 2 was 110KPa and the column bottom operating temperature was 130 ℃.
The operating pressure of the dephosgene tower 3 is 110KPa, the operating temperature of the tower kettle is 150 ℃, and the condensing liquid phase at the tower top is 70 ℃.
The operating pressure of the solvent removal tower 4 is 50KPa, the operating temperature of the tower kettle is 130 ℃, and the temperature of the condensing liquid phase at the tower top is 80 ℃.
The operating pressure of the solvent refining tower 5 is 102KPa, and the temperature of the tower kettle is 160 ℃. The overhead condensed liquid phase temperature was 70 ℃.
Chlorobenzene was fed into the absorber 1 through the absorber solvent feed pipe 16 in an amount of about 20m 3/h, and fed from the bottom of the absorber 1 to the crude solvent buffer tank 6.
Chlorobenzene is added into the phosgenation reactor 2 from a solvent feed pipe 17 of the phosgenation reactor, the feeding amount is about 80m 3/h, the top gas phase of the phosgenation reactor 2 enters the tower kettle of the absorption tower 1, and the bottom liquid phase of the phosgenation reactor 2 enters the middle part of the dephosgene tower 3.
The gas phase at the top of the dephosgene tower 3 is condensed by a dephosgene tower and a solvent refining tower top condenser 14 and then enters a gas-liquid separation tank 9 at the top of the dephosgene tower and the solvent refining tower; the liquid phase in the tower bottom of the dephosgene tower 3 enters the upper part of the solvent removal tower 4.
The gas phase at the top of the solvent removal tower 4 is condensed by a solvent removal tower top cooler 15 and then enters a solvent removal tower top gas-liquid separation tank 8 to obtain gas phase and liquid phase, the obtained gas phase enters the tower kettle of the absorption tower 1, and the liquid phase enters a solvent storage tank 7.
The solvent of the crude solvent buffer tank 6 enters the upper part of the solvent refining tower 5, and the gas phase at the top of the solvent refining tower 5 enters the gas-liquid separation tank 9 at the top of the phosgene removal tower and the solvent refining tower after being condensed by the phosgene removal tower and the solvent refining tower top cooler 14;
Gas-liquid separation is carried out in a gas-liquid separation tank 9 at the top of the dephosgene tower and the solvent refining tower to obtain gas phase and liquid phase, and the obtained gas phase enters the tower bottom of the absorption tower 1; after the solvent refining tower 5 runs stably, water contained in the liquid phase in the gas-liquid separation tank 9 at the top of the phosgene removing tower and the solvent refining tower is enriched and layered, water is discharged once every 2 hours through the water discharge pipe 19, and the layered water is intermittently discharged out of the system at a flow rate of 1m 3/h for 0.5 hour each time, so that the water in the system is reduced. The liquid phase at the bottom of the solvent refining tower 5 is sent to a solvent storage tank 7.
The exhaust gas is discharged from the exhaust gas discharge pipe 18.
When the method was operated and the water content of chlorobenzene in the crude solvent buffer tank 6 was monitored to decrease to 100ppm (the crude solvent buffer tank was up to the standard) from the time when the operation (temperature, pressure) of the solvent refining column 5 was stabilized, the system drainage time was as shown in table 1.
Example 3
This example is a water removal process for a phosgenation isocyanate production plant using the water removal system of example 1. Before solvent feeding, the system was dried to a dew point of-40 ℃ using nitrogen purge at normal pressure.
The solvent was chlorobenzene, the moisture content in the chlorobenzene was 0.0270wt%, based on the mass of the solvent, the temperature was 30 ℃.
The absorption tower 1 is a packed tower, and the top operating pressure is 120KP.
The top operating pressure of the phosgenation reactor 2 is 130KPa, and the operating temperature of the tower kettle is 150 DEG C
The operating pressure of the dephosgene tower 3 is 130KPa of gauge pressure, the operating temperature of the tower kettle is 165 ℃, and the condensing liquid phase at the tower top is 80 ℃.
The operating pressure of the solvent removal tower 4 is 30KPa, the operating temperature of the tower kettle is 110 ℃, and the temperature of the condensing liquid phase at the tower top is 80 ℃.
The operation pressure gauge pressure of the solvent refining tower 5 is 130KPa, the temperature of the tower bottom is 170 ℃, and the temperature of the tower top condensed liquid phase is 80 ℃.
Chlorobenzene was fed into the absorber 1 through the absorber solvent feed pipe 16 in an amount of about 20m 3/h, and fed from the bottom of the absorber 1 to the crude solvent buffer tank 6.
Chlorobenzene is added into the phosgenation reactor 2 from a solvent feed pipe 17 of the phosgenation reactor, the feeding amount is about 80m 3/h, the top gas phase of the phosgenation reactor 2 enters the tower kettle of the absorption tower 1, and the bottom liquid phase of the phosgenation reactor 2 enters the middle part of the dephosgene tower 3.
The gas phase at the top of the dephosgene tower 3 is condensed by a dephosgene tower and a solvent refining tower top condenser 14 and then enters a gas-liquid separation tank 9 at the top of the dephosgene tower and the solvent refining tower; the liquid phase in the tower bottom of the dephosgene tower 3 enters the upper part of the solvent removal tower 4.
The gas phase at the top of the solvent removal tower 4 is condensed by a solvent removal tower top cooler 15 and then enters a solvent removal tower top gas-liquid separation tank 8 to obtain gas phase and liquid phase, the obtained gas phase enters the tower kettle of the absorption tower 1, and the liquid phase enters a solvent storage tank 7.
The solvent of the crude solvent buffer tank 6 enters the upper part of the solvent refining tower 5, and the gas phase at the top of the solvent refining tower 5 enters the gas-liquid separation tank 9 at the top of the phosgene removal tower and the solvent refining tower after being condensed by the phosgene removal tower and the solvent refining tower top cooler 14;
Gas-liquid separation is carried out in a gas-liquid separation tank 9 at the top of the dephosgene tower and the solvent refining tower to obtain gas phase and liquid phase, and the obtained gas phase enters the tower bottom of the absorption tower 1; after the solvent refining tower 5 runs stably, water contained in the liquid phase in the gas-liquid separation tank 9 at the top of the phosgene removing tower and the solvent refining tower is enriched and layered, water is discharged once every 2 hours through the water discharge pipe 19, and the layered water is intermittently discharged out of the system at a flow rate of 1m 3/h for 0.5 hour each time, so that the water in the system is reduced. The liquid phase at the bottom of the solvent refining tower 5 is sent to a solvent storage tank 7.
The exhaust gas is discharged from the exhaust gas discharge pipe 18.
When the method was operated and the water content of chlorobenzene in the crude solvent buffer tank 6 was monitored to decrease to 100ppm (the crude solvent buffer tank was up to the standard) from the time when the operation (temperature, pressure) of the solvent refining column 5 was stabilized, the system drainage time was as shown in table 1.
Comparative example 1
The water removal system for the phosgenation isocyanate production apparatus shown in FIG. 2 was used, the arrangement of the liquid phase lines 20 and 21 in example 1 was omitted, and instead, the bottom of the column bottom of the absorption column 1 and the column bottom of the phosgenation reactor 2 were connected by using a liquid phase line 22, and the top gas-liquid separation tank 8 of the solvent removal column and the crude solvent buffer tank 6 were connected by a liquid phase line 23. The system is a normal production system of a device for producing isocyanate by phosgenation. Before solvent feeding, the system was dried to a dew point of-40 ℃ using nitrogen purge at normal pressure.
The solvent was chlorobenzene, the moisture content in the chlorobenzene was 0.0270wt%, based on the mass of the solvent, the temperature was 30 ℃.
The absorption tower 1 is a packed tower, and the top operating pressure is 100KPa.
The top operating pressure gauge pressure of the phosgenation reactor 2 was 110KPa and the bottom operating temperature was 130 ℃.
The operating pressure of the dephosgene tower 3 is 110KPa, the operating temperature of the tower kettle is 150 ℃, and the condensing liquid phase at the tower top is 70 ℃.
The operation pressure gauge pressure of the solvent removal tower 4 is 50KPa, the operation temperature of the tower kettle is 110 ℃, and the temperature of the tower top condensed liquid phase is 80 ℃.
The operating pressure gauge pressure of the solvent refining tower 5 is 110KPa, and the temperature of the tower kettle is 165 ℃. The overhead condensed liquid phase temperature was 70 ℃.
Chlorobenzene was fed to absorber 1 via absorber solvent feed line 16 at a feed rate of about 20m 3/h and fed from the bottom of absorber 1 to the bottom of phosgenation reactor 2.
Chlorobenzene is added into the phosgenation reactor 2 from a solvent feed pipe 17 of the phosgenation reactor, the feeding amount is about 80m 3/h, the top gas phase of the phosgenation reactor 2 enters the tower kettle of the absorption tower 1, and the bottom liquid phase of the phosgenation reactor 2 enters the middle part of the dephosgene tower 3.
The gas phase at the top of the dephosgene tower 3 is condensed by a dephosgene tower and a solvent refining tower top condenser 14 and then enters a gas-liquid separation tank 9 at the top of the dephosgene tower and the solvent refining tower; the liquid phase in the tower bottom of the dephosgene tower 3 enters the upper part of the solvent removal tower 4.
The gas phase at the top of the solvent removal tower 4 is condensed by a solvent removal tower top cooler 15 and then enters a solvent removal tower top gas-liquid separation tank 8 to obtain gas phase and liquid phase, the obtained gas phase enters the tower kettle of the absorption tower 1, and the liquid phase enters a crude solvent buffer tank 6.
The solvent of the crude solvent buffer tank 6 enters the upper part of the solvent refining tower 5, and the gas phase at the top of the solvent refining tower 5 enters the gas-liquid separation tank 9 at the top of the phosgene removal tower and the solvent refining tower after being condensed by the phosgene removal tower and the solvent refining tower top cooler 14;
Gas-liquid separation is carried out in a gas-liquid separation tank 9 at the top of the dephosgene tower and the solvent refining tower to obtain gas phase and liquid phase, and the obtained gas phase enters the tower bottom of the absorption tower 1; after the solvent refining tower 5 runs stably, water contained in the liquid phase in the gas-liquid separation tank 9 at the top of the phosgene removing tower and the solvent refining tower is enriched and layered, water is discharged once every 2 hours through the water discharge pipe 19, and the layered water is intermittently discharged out of the system at a flow rate of 1m 3/h for 0.5 hour each time, so that the water in the system is reduced. The liquid phase at the bottom of the solvent refining tower 5 is sent to a solvent storage tank 7.
The exhaust gas is discharged from the exhaust gas discharge pipe 18.
When the method was operated and the water content of chlorobenzene in the crude solvent buffer tank 6 was monitored to decrease to 100ppm (the crude solvent buffer tank was up to the standard) from the time when the operation (temperature, pressure) of the solvent refining column 5 was stabilized, the system drainage time was as shown in table 1.
Table 1 results of examples and comparative examples
From Table 1, the method of the invention can rapidly and efficiently reduce the water content in the initial system of the device for producing isocyanate by phosgenation, greatly shorten the water removal time of the device in the initial driving stage and save energy consumption.
Claims (16)
1. A water removal system for a phosgenation isocyanate production apparatus comprising: an absorption tower (1), a phosgenation reactor (2), a dephosgene tower (3), a solvent removal tower (4), a solvent removal tower top cooler (15), a solvent removal tower top gas-liquid separation tank (8), a crude solvent buffer tank (6), a solvent refining tower (5), a dephosgene tower, a solvent refining tower top cooler (14), a dephosgene tower, a solvent refining tower top gas-liquid separation tank (9) and a solvent storage tank (7);
An absorption tower solvent feed pipe (16) is arranged at the upper part of the absorption tower (1), the bottom of the tower kettle of the absorption tower (1) is connected with a crude solvent buffer tank (6) through a liquid phase pipeline (20), the crude solvent buffer tank (6) is connected with the upper part of a solvent refining tower (5), the top of the solvent refining tower (5) is connected with a dephosgene tower and a solvent refining tower top cooler (14) through a gas phase pipeline,
A solvent removal tower kettle reboiler (12) is arranged at the bottom of the solvent removal tower (4);
The bottom of the tower kettle of the solvent refining tower (5) is connected with a solvent storage tank (7) through a liquid phase pipeline;
The upper part of the phosgenation reactor (2) is provided with a solvent feed pipe (17) of the phosgenation reactor, and the top of the phosgenation reactor (2) is connected with the tower kettle of the absorption tower (1) through a gas phase pipeline;
The bottom of a tower kettle of the phosgenation reactor (2) is connected with the middle part of a dephosgene tower (3) through a liquid phase pipeline, the top of the dephosgene tower (3) is connected with a dephosgene tower and a solvent refining tower top cooler (14) through a gas phase pipeline, the bottom of the tower kettle of the dephosgene tower (3) is connected with the upper part of a solvent removal tower (4) through a liquid phase pipeline, the top of the solvent removal tower (4) is connected with a solvent removal tower top cooler (15) through a gas phase pipeline, the solvent removal tower top cooler (15) is connected with a solvent removal tower top gas-liquid separation tank (8), the bottom of the solvent removal tower top gas-liquid separation tank (8) is connected with a solvent storage tank (7) through a liquid phase pipeline, and the top of the solvent removal tower top gas-liquid separation tank (8) is connected with the tower kettle of the absorption tower (1);
The top part of the dephosgene tower and the solvent refining tower top gas-liquid separation tank (9) is connected with the tower kettle of the absorption tower (1) through a gas phase pipeline, and the bottom part of the dephosgene tower and the solvent refining tower top gas-liquid separation tank (9) is connected with the upper part of the solvent refining tower (5) through a liquid phase pipeline, and a drain pipe (19) is arranged on the dephosgene tower and the solvent refining tower top gas-liquid separation tank (9);
The top of the absorption tower (1) is provided with a tail gas discharge pipe (18).
2. The water removal system as claimed in claim 1, wherein the solvent storage tank (7) is connected via a line to the absorber solvent feed line (16) and/or the phosgenation reactor solvent feed line (17), optionally with a cooler being provided on the line connecting the solvent storage tank (7) to the absorber solvent feed line (16) and/or the phosgenation reactor solvent feed line (17).
3. A method of removing water according to the water removal system of claim 1 or 2, comprising the steps of;
Adding solvent into the absorption tower (1) from a solvent feed pipe (16) of the absorption tower, and leading the solvent to a crude solvent buffer tank (6) from the bottom of the tower kettle of the absorption tower (1); the solvent of the crude solvent buffer tank (6) enters the upper part of the solvent refining tower (5), and the top gas phase of the solvent refining tower (5) enters the gas-liquid separation tank (9) at the top of the phosgene removal tower and the solvent refining tower after being condensed by the phosgene removal tower and the solvent refining tower top cooler (14); the liquid phase produced from the bottom of the tower kettle of the solvent refining tower (5) enters a solvent storage tank (7);
Adding solvent into the phosgenation reactor (2) from a solvent feed pipe (17) of the phosgenation reactor, enabling a top gas phase of the phosgenation reactor (2) to enter a tower kettle of the absorption tower (1), and enabling a liquid phase at the bottom of the tower kettle of the phosgenation reactor (2) to enter the middle part of the dephosgene tower (3);
The gas phase at the top of the dephosgene tower (3) enters a gas-liquid separation tank (9) at the top of the dephosgene tower and the solvent refining tower after being condensed by a cooler (14) at the top of the dephosgene tower and the solvent refining tower;
The gas phase and the liquid phase are obtained in a gas-liquid separation tank (9) at the top of the dephosgene tower and the solvent refining tower, the obtained gas phase enters a tower kettle of an absorption tower (1), the obtained liquid phase enters the upper part of a solvent refining tower (5), water is enriched and layered in the gas-liquid separation tank (9) at the top of the dephosgene tower and the solvent refining tower, and is discharged through a water discharge pipe (19);
The liquid phase produced at the bottom of the tower kettle of the dephosgene tower (3) enters the upper part of a solvent removal tower (4), the top gas phase of the solvent removal tower (4) enters a solvent removal tower top gas-liquid separation tank (8) after being condensed by a solvent removal tower top cooler (15) to obtain gas phase and liquid phase, the obtained gas phase enters the tower kettle of the absorption tower (1), and the obtained liquid phase enters a solvent storage tank (7);
The tail gas is discharged from a tail gas discharge pipe (18).
4. A method according to claim 3, characterized in that the solvent in the solvent reservoir (7) is supplied as solvent to the absorber solvent feed pipe (16) and/or the phosgenation reactor solvent feed pipe (17).
5. A process according to claim 3, wherein the solvent is selected from one or more of diethyl isophthalate, benzene, toluene, xylene, chlorobenzene and o-dichlorobenzene.
6. A method according to claim 3, wherein the moisture content of the solvent is 0-0.400wt%.
7. A method according to claim 3, wherein the temperature of the solvent is 10-60 ℃.
8. A method according to claim 3, characterized in that the gauge pressure of the absorber column (1) is 100-150KPa;
The gauge pressure of the phosgenation reactor (2) is 100-150KPa; the temperature of the tower kettle of the phosgenation reactor (2) is 130-170 ℃;
the gauge pressure of the dephosgene tower (3) is 100-150KPa; the temperature of the tower kettle of the dephosgene tower (3) is 130-170 ℃;
The gauge pressure of the solvent removal tower (4) is 20-80KPa; the temperature of the tower kettle of the solvent removal tower (4) is 100-150 ℃;
The gauge pressure of the solvent refining tower (5) is 100-150KPa; the temperature of the tower kettle of the solvent refining tower (5) is 130-180 ℃.
9. A process according to claim 3, characterized in that the condensed liquid phase temperature in the dephosgene column and solvent refining overhead cooler (14) is 50-100 ℃; the condensed liquid phase temperature in the solvent removal overhead cooler (15) is 50-100 ℃.
10. A method according to claim 3, wherein the moisture content in the solvent is 0-0.0300wt%.
11. A method according to claim 3, wherein the temperature of the solvent is 20-50 ℃.
12. A method according to claim 3, characterized in that the gauge pressure of the absorber column (1) is 100-130KPa;
The gauge pressure of the phosgenation reactor (2) is 100-130KPa; the temperature of the tower kettle of the phosgenation reactor (2) is 140-160 ℃;
The gauge pressure of the dephosgene tower (3) is 100-130KPa; the temperature of the tower kettle of the dephosgene tower (3) is 140-160 ℃;
The gauge pressure of the solvent removal tower (4) is 30-70KPa; the temperature of the tower kettle of the solvent removal tower (4) is 110-140 ℃;
the gauge pressure of the solvent refining tower (5) is 100-130KPa; the temperature of the tower kettle of the solvent refining tower (5) is 140-170 ℃.
13. A process according to claim 3, characterized in that the condensed liquid phase temperature in the dephosgene column and solvent refining overhead cooler (14) is 60-90 ℃; the condensed liquid phase temperature in the solvent removal overhead cooler (15) is 60-90 ℃.
14. A method according to claim 3, wherein the temperature of the solvent is 30-40 ℃.
15. A method according to claim 3, characterized in that the gauge pressure of the absorber column (1) is 100-110KPa;
The gauge pressure of the phosgenation reactor (2) is 100-110KPa; the temperature of the tower kettle of the phosgenation reactor (2) is 150-160 ℃;
The gauge pressure of the dephosgene tower (3) is 100-110KPa; the temperature of the tower kettle of the dephosgene tower (3) is 150-160 ℃;
the gauge pressure of the solvent removal tower (4) is 40-60KPa; the temperature of the tower kettle of the solvent removal tower (4) is 120-130 ℃;
the gauge pressure of the solvent refining tower (5) is 100-110KPa; the temperature of the tower kettle of the solvent refining tower (5) is 150-160 ℃.
16. A process according to claim 3, characterized in that the condensed liquid phase temperature in the dephosgene column and solvent refining overhead cooler (14) is 70-80 ℃; the condensed liquid phase temperature in the solvent removal overhead cooler (15) is 70-80 ℃.
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| CN107935889A (en) * | 2017-11-29 | 2018-04-20 | 万华化学集团股份有限公司 | The preparation method and system of a kind of monoisocyanates |
| CN210001801U (en) * | 2019-03-27 | 2020-01-31 | 万华化学集团股份有限公司 | Water removal system of phosgenation isocyanate production device |
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| CN103613515A (en) * | 2013-12-13 | 2014-03-05 | 青岛科技大学 | Method for recycling phosgene during isocyanate production process |
| CN107353231A (en) * | 2017-07-17 | 2017-11-17 | 薛永和 | A kind of method for preparing organic isocyanate |
| CN107652208A (en) * | 2017-08-30 | 2018-02-02 | 万华化学（宁波）有限公司 | The method and system of desolvation in a kind of isocyanate product obtained from phosgenation reaction |
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