CN114344930A - Caprolactam distillation vacuum-pumping method and device thereof - Google Patents
Caprolactam distillation vacuum-pumping method and device thereof Download PDFInfo
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- CN114344930A CN114344930A CN202111453547.3A CN202111453547A CN114344930A CN 114344930 A CN114344930 A CN 114344930A CN 202111453547 A CN202111453547 A CN 202111453547A CN 114344930 A CN114344930 A CN 114344930A
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- caprolactam
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Abstract
The invention discloses a caprolactam distillation vacuum-pumping method and a device thereof. The invention adopts a dry vacuum pump as vacuum pumping equipment, caprolactam melt is heated by steam through a heater at the bottom of a distillation tower, caprolactam is evaporated under high vacuum and condensed and recovered at the top of the distillation tower to obtain a caprolactam finished product, uncondensed water and caprolactam gas are pumped out by the dry vacuum pump, after the caprolactam is further condensed by a cooler outside the distillation tower, the gas without caprolactam is pumped out through a dry vacuum pump set and discharged, and the condensed caprolactam is returned to a system for reuse. The method and the device adopting the dry vacuum pump as the vacuumizing equipment can replace the traditional vacuumizing equipment of the steam jet pump, save steam, reduce steam condensate of the system, save investment and operation cost and have good industrial application value.
Description
Technical Field
The invention relates to a caprolactam distillation and vacuum-pumping method and a system thereof, in particular to a caprolactam distillation and vacuum-pumping method and a system thereof.
Background
Caprolactam is an important petrochemical product and one of important organic chemical raw materials, is mainly used for generating polyamide slices (usually called nylon-6 slices or nylon-6 slices) by polymerization, and can be further processed into nylon fibers, engineering plastics and plastic films. The quality of caprolactam has great influence on the quality of downstream polymerization and spinning, and in order to remove heavy component impurities in the caprolactam, the caprolactam needs to be distilled, and the caprolactam is evaporated into gas and then condensed and recovered by utilizing the difference of the boiling points of the caprolactam and the impurities. Because the boiling point of caprolactam is 270 ℃ under normal pressure and 130-140 ℃ under negative pressure of-99 KPa to-100 KPa, the heavy components are removed by adopting negative pressure distillation.
At present, the traditional caprolactam distillation technology in China adopts a single steam jet vacuum pumping technology, utilizes steam as power to pump out air in equipment, and the equipment is operated under negative pressure. The steam jet pump has the advantages of stable operation and simple operation, and has the disadvantages that steam is consumed, and simultaneously steam condensate water and caprolactam are mixed into caprolactam water solution, so that the water quantity of a system is increased and water needs to be removed. Therefore, the method and the device adopting the dry vacuum pump as the vacuumizing equipment can replace the traditional vacuumizing equipment of the steam jet pump, save steam, reduce steam condensate water of the system, save investment and operation cost, and have good industrial application value.
Disclosure of Invention
The invention discloses a caprolactam distillation vacuum-pumping method and a device thereof. The invention aims at the distillation process of caprolactam, and provides a novel vacuumizing method and equipment without consuming steam, and the recovery rate of caprolactam can be improved.
The purpose of the invention is realized by the following steps: the caprolactam distillation vacuum-pumping method comprises the following steps:
(1) under the condition of vacuum pumping of a dry vacuum pump, the distillation tower is in a vacuum state;
(2) heating a caprolactam melt, evaporating and condensing under vacuum, and enabling the liquid to flow into a caprolactam storage tank;
(3) pumping gas, cooling by an external cooler of the distillation tower, enabling caprolactam liquid to flow into a caprolactam liquid seal tank, filling the caprolactam liquid into the caprolactam liquid seal tank in advance, filling pure caprolactam liquid into a caprolactam storage tank, and enabling the caprolactam liquid to flow into the bottom of the caprolactam storage tank through a condensate pipeline;
(4) the uncondensed gas is discharged through a dry vacuum pump.
Further, in the step (2), the temperature of a heater at the bottom of the distillation tower is 130-145 ℃, and the vacuum pressure is-99-100 kpa.
And (3) further, in the step (2), a hot water condenser is arranged at the top of the distillation tower, the temperature of hot water is 80-90 ℃, and caprolactam steam is condensed by the hot water condenser to form liquid for recovery.
Further, in the step (3), hot water with the temperature of 70-75 ℃ is introduced into a cooler to cool the caprolactam gas into liquid.
The dry vacuum pump is composed of two or more pumps including Roots vacuum pump, multi-stage claw pump, single claw pump, and screw vacuum pump.
Furthermore, the dry vacuum pump controls the load in a variable frequency mode, and the controller controls the working load of the dry vacuum pump through manual instruction and/or collection of the steam amount introduced into the distillation tower.
A caprolactam distillation vacuum pumping device comprises a distillation tower, a cooler and a dry vacuum pump, wherein the cooler is arranged at the top of the distillation tower, and the dry vacuum pump is connected with the distillation tower and controls the internal vacuum degree of the distillation tower in real time; the dry vacuum pump is a combination of two of a Roots vacuum pump, a multi-stage claw pump, a single claw pump and a screw vacuum pump.
Further, the caprolactam condensate discharge end at the top of the distillation tower flows to a caprolactam storage tank through a material downcomer; and the condensate discharge end of the distillation tower top cooler flows to the caprolactam liquid seal tank through a material downcomer.
Furthermore, the cooling medium of the cooler flows into the distillation tower after heat exchange to condense caprolactam therein to form lactam condensate.
Step by step, a liquid supply ring with a ring is arranged at the bottom of the distillation tower, a nozzle is arranged on the liquid supply ring, and the nozzle sprays to the bottom of the distillation tower; the caprolactam melt is heated in the liquid supply ring to 130-145 ℃.
The invention provides a caprolactam distillation vacuum-pumping method and a device thereof, which have the beneficial effects that:
(1) the traditional caprolactam distillation vacuum method and the device thereof adopt a steam jet pump as equipment, medium-pressure steam as power and gas in a distillation tower is sucked by steam jet, so that vacuum is ensured. Due to the high steam consumption, steam condenses with the caprolactam into an aqueous caprolactam solution, resulting in an increase in system water. In the invention, the caprolactam distillation is to pump out gas through a dry vacuum pump set under the condition of no steam and a steam jet pump, thereby greatly saving the steam consumption and simultaneously not increasing the water content in the system.
(2) The caprolactam storage tank and the caprolactam liquid seal tank correspond to cooling recovery in the distillation tower and cooling recovery outside the distillation tower, and the caprolactam recovery rate is improved by 2 to 4 percent through secondary cooling recovery under the condition of not increasing an external system.
(3) Because no steam is consumed, the heat exchange area of equipment needing a cooler is also greatly reduced, and the equipment investment and the cooling water quantity are reduced.
(4) Because no steam is consumed, the water quantity is further reduced, and the water treatment cost is further saved.
(5) The dry vacuum pump is formed by combining two or more pumps, the Roots vacuum pump, the multi-stage claw pump, the single-machine claw pump and the screw vacuum pump are combined randomly, so that the change range of the vacuum degree is greatly reduced, and after a plurality of tests, two vacuum pumps of the same type are found to be adopted, the combined vacuum fluctuation range is generally 4-7%, and can not be controlled to be more than 4%, and two different vacuum pumps are adopted, the vacuum fluctuation range can be well controlled to be 0.6-1.2%, the working content of the system is that two vacuum pumps work simultaneously, one is a main vacuum pump, the other is an auxiliary vacuum pump, the auxiliary vacuum pump is 75-80% of the working power of the main vacuum pump, when the entering materials are increased, when the power required to be increased is less than or equal to 2% within 25 seconds, increasing the working power to the power required to be increased within 10 seconds for the auxiliary vacuum pump, and not adjusting the main vacuum pump; the entering materials are reduced, when the reduction power is less than or equal to 2% within 25 seconds, the required working power is reduced within 10 seconds for the main vacuum pump, and the working power of the auxiliary vacuum pump is not adjusted; if the material is increased within 25 seconds and the power is required to be increased by more than 2% and less than or equal to 5%, the working power of the auxiliary vacuum pump is increased within 10 seconds to increase the total power by 2% -2.5%, the main vacuum pump is started within 5-8 seconds after the auxiliary vacuum pump works, and the total power increase is completed within 10 seconds; if the entering materials are reduced, when the power is required to be reduced by more than 2% and less than or equal to 5% in 25 seconds, the working power of the main vacuum pump is increased in 10 seconds to reduce the total power by 2% -2.5%, and the auxiliary vacuum pump is started after the main vacuum pump works for 5-8 seconds and completes the total power increase in 10 seconds. The roots vacuum pump, multistage claw formula pump, unit claw formula pump, screw vacuum pump no matter that do main vacuum pump still assist the vacuum pump all can, theory of operation prevents that two vacuum pumps from adjusting the fluctuation of control vacuum degree that can be better simultaneously, and the material change generally can know concrete data 15-30 seconds in advance, and its control vacuum pump concrete time generally does, increases or reduces about 5-8 seconds before the material gets into the distillation column, begins to carry out power adjustment.
Drawings
FIG. 1 is a schematic diagram of a caprolactam vacuum extractor.
Fig. 2 is a schematic diagram of the recycling of the cooling liquid in the cooler.
FIG. 3 is a schematic diagram of the operation of the liquid supply ring.
As shown in the figure, the distillation tower S, a cooler E, a dry vacuum pump P, a caprolactam storage tank V1, a caprolactam liquid seal tank V2, a liquid supply ring 5 and a nozzle 6.
Detailed Description
The present invention is further illustrated by the following specific examples, which should be noted that the following examples are only illustrative and the present invention is not limited thereto.
As shown in fig. 1, a caprolactam distillation vacuum extractor comprises a distillation tower S, a cooler E and a dry vacuum pump P, wherein the cooler E is arranged at the top of the distillation tower S, and the dry vacuum pump P is connected with the distillation tower S and controls the internal vacuum degree of the distillation tower S in real time; the dry vacuum pump P is a combination of two of a Roots vacuum pump, a multi-stage claw pump, a single-machine claw pump and a screw vacuum pump, so that the fluctuation range of the vacuum degree of the distillation tower T is smaller than 1.2%, the distillation effect is greatly improved, and according to the existing test, the fluctuation range of the vacuum degree is smaller than 2%, and the distillation effect is improved by more than 2.8%.
Preferably, the caprolactam condensate discharge end at the top of the distillation tower S flows to a caprolactam storage tank V1 through a material underflow pipe; the condensate discharge end of the cooler E flows to the caprolactam hydraulic seal tank V2 through a material downcomer.
As shown in FIG. 2, the cooling medium of the cooler E is heat-exchanged and flows into the distillation column S to condense caprolactam therein to form a lactam condensate.
As shown in fig. 3, a liquid supply ring 5 with a ring shape is arranged at the bottom of the distillation tower S, a nozzle is arranged on the liquid supply ring, the nozzle 6 sprays towards the bottom of the distillation tower S, the nozzle 6 on the liquid supply ring 5 sprays towards the bottom of the distillation tower S to increase the path of the liquid entering the distillation tower S, and simultaneously, under the action of impact force, the liquid is dispersed in the distillation tower S to facilitate gasification, in the prior art, the liquid is mostly directly sprayed towards the middle of the distillation tower S, although the direction is simply changed, the distillation effect is improved by about 1%; the caprolactam melt is heated to the temperature of 130-.
The caprolactam distillation vacuum-pumping method comprises the following steps:
(1) the distillation tower is in a vacuum state under the condition that the dry vacuum pump is used for vacuumizing, and preferably, the dry vacuum pump is formed by combining two or more pumps, including a roots vacuum pump, a multi-stage claw pump, a single-machine claw pump and a screw vacuum pump.
Furthermore, the dry vacuum pump controls the load in a variable frequency mode, and the controller controls the working load of the dry vacuum pump through manual instruction and/or collection of the steam amount introduced into the distillation tower.
(2) Heating a caprolactam melt, evaporating and condensing under vacuum, and enabling the liquid to flow into a caprolactam storage tank, wherein preferably, in the step (2), the heater temperature at the bottom of the distillation tower is 130-145 ℃, and the vacuum pressure is-99-100 kpa; further preferably, in the step (2), a hot water condenser is arranged at the top of the distillation tower, the temperature of hot water is 80-90 ℃, and caprolactam steam is condensed by the hot water condenser to form liquid for recovery.
(3) And (3) preferably, hot water at the temperature of between 70 and 75 ℃ is introduced into the cooler to cool the caprolactam gas into liquid.
(4) The uncondensed gas is discharged through a dry vacuum pump.
Preferred embodiments of the present invention have been described above in detail, but the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution, which all belong to the scope of protection of the invention.
Claims (10)
1. A caprolactam distillation vacuum-pumping method is characterized in that: the method comprises the following steps:
(1) under the condition of vacuum pumping of a dry vacuum pump, the distillation tower is in a vacuum state;
(2) heating a caprolactam melt, evaporating and condensing under vacuum, and enabling the liquid to flow into a caprolactam storage tank;
(3) pumping gas out, cooling by a cooler outside the distillation tower, enabling the caprolactam liquid to flow into a caprolactam liquid seal tank, pre-filling the caprolactam liquid into the caprolactam liquid seal tank, filling pure caprolactam liquid into a caprolactam storage tank (V2), and enabling the caprolactam liquid to flow into the bottom of the caprolactam storage tank (V2) through a condensate pipeline;
(4) the uncondensed gas is discharged through a dry vacuum pump.
2. The vacuum distillation method of caprolactam as claimed in claim 1, wherein in the step (2), the heater temperature at the bottom of the distillation column is 130-145 ℃, and the vacuum pressure is-99-100 kpa.
3. The vacuum distillation method of caprolactam as claimed in claim 1, wherein in step (2), the top of the distillation tower is provided with a hot water condenser, the temperature of hot water is 80-90 ℃, and caprolactam vapor is condensed by the hot water condenser to form liquid for recovery.
4. The vacuum distillation method of caprolactam as claimed in claim 1, wherein in step (3), hot water at 70-75 ℃ is introduced into the cooler to cool the caprolactam gas into liquid.
5. A process for the distillation and evacuation of caprolactam according to any of claims 1 to 4,
the dry vacuum pump is formed by combining two or more than two pumps, including a Roots vacuum pump, a multi-stage claw pump, a single-machine claw pump and a screw vacuum pump.
6. The method for distilling and vacuumizing caprolactam according to claim 5, wherein the dry vacuum pump is a variable frequency control load, and the controller controls the working load of the dry vacuum pump by manually commanding and/or acquiring the steam amount fed into the distillation tower.
7. A caprolactam distillation evacuating device, its support is: the device comprises a distillation tower (S), a cooler (E) and a dry vacuum pump (P), wherein the cooler (E) is arranged at the top of the distillation tower (S), and the dry vacuum pump (P) is connected with the distillation tower (S) and controls the internal vacuum degree of the distillation tower (S) in real time; the dry vacuum pump (P) is a combination of two of a Roots vacuum pump, a multi-stage claw pump, a single claw pump and a screw vacuum pump.
8. The caprolactam distillation vacuum extractor of claim 7, wherein the caprolactam distillation vacuum extractor is characterized in that: the caprolactam condensate discharge end at the top of the distillation tower (S) flows to a caprolactam storage tank (V1) through a material downcomer; the condensate discharge end of the cooler (E) flows to a caprolactam liquid seal tank (V2) through a material downcomer.
9. The caprolactam distillation vacuum extractor of claim 8, wherein the caprolactam distillation vacuum extractor is characterized in that: the cooling medium of the cooler (E) flows into the distillation tower (S) after heat exchange to condense caprolactam therein to form lactam condensate.
10. The caprolactam distillation vacuum extractor of claim 7, wherein the caprolactam distillation vacuum extractor is characterized in that: a liquid supply ring which is shaped like a ring is arranged at the bottom of the distillation tower (S), a nozzle is arranged on the liquid supply ring, and the nozzle sprays to the bottom of the distillation tower (S); the caprolactam melt is heated in the liquid supply ring to 130-145 ℃.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111453547.3A CN114344930A (en) | 2021-12-01 | 2021-12-01 | Caprolactam distillation vacuum-pumping method and device thereof |
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| CN202111453547.3A CN114344930A (en) | 2021-12-01 | 2021-12-01 | Caprolactam distillation vacuum-pumping method and device thereof |
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| JP2007223906A (en) * | 2006-02-21 | 2007-09-06 | Sumitomo Chemical Co Ltd | Method for purifying caprolactam |
| CN205549654U (en) * | 2016-03-30 | 2016-09-07 | 福建青松股份有限公司 | Distillation equipment |
| CN106008345A (en) * | 2015-02-13 | 2016-10-12 | 中国石油化学工业开发股份有限公司 | Process for producing caprolactam and system therefor |
| CN211284206U (en) * | 2019-12-11 | 2020-08-18 | 陈天然 | Caprolactam purification device in 6-aminocapronitrile preparation process |
| CN111635348A (en) * | 2020-06-22 | 2020-09-08 | 聊城鲁西聚酰胺新材料科技有限公司 | Application and system of screw vacuum pump in caprolactam refining process production |
| CN111848515A (en) * | 2020-07-14 | 2020-10-30 | 中国石油化工股份有限公司 | Novel rectification method of caprolactam product |
| CN214436598U (en) * | 2020-11-16 | 2021-10-22 | 南京真空泵厂有限公司 | Cyclohexanone rectification vacuum apparatus |
| CN216629702U (en) * | 2021-12-01 | 2022-05-31 | 湖北三宁化工股份有限公司 | Caprolactam distillation evacuating device |
-
2021
- 2021-12-01 CN CN202111453547.3A patent/CN114344930A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007223906A (en) * | 2006-02-21 | 2007-09-06 | Sumitomo Chemical Co Ltd | Method for purifying caprolactam |
| CN106008345A (en) * | 2015-02-13 | 2016-10-12 | 中国石油化学工业开发股份有限公司 | Process for producing caprolactam and system therefor |
| CN205549654U (en) * | 2016-03-30 | 2016-09-07 | 福建青松股份有限公司 | Distillation equipment |
| CN211284206U (en) * | 2019-12-11 | 2020-08-18 | 陈天然 | Caprolactam purification device in 6-aminocapronitrile preparation process |
| CN111635348A (en) * | 2020-06-22 | 2020-09-08 | 聊城鲁西聚酰胺新材料科技有限公司 | Application and system of screw vacuum pump in caprolactam refining process production |
| CN111848515A (en) * | 2020-07-14 | 2020-10-30 | 中国石油化工股份有限公司 | Novel rectification method of caprolactam product |
| CN214436598U (en) * | 2020-11-16 | 2021-10-22 | 南京真空泵厂有限公司 | Cyclohexanone rectification vacuum apparatus |
| CN216629702U (en) * | 2021-12-01 | 2022-05-31 | 湖北三宁化工股份有限公司 | Caprolactam distillation evacuating device |
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