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CN-121971960-A - Tail gas treatment method for NMP production device

CN121971960ACN 121971960 ACN121971960 ACN 121971960ACN-121971960-A

Abstract

The invention belongs to the technical field of tail gas treatment, and particularly discloses a tail gas treatment method of an NMP production device, wherein tail gas is discharged into a first tail gas absorption tower for absorption, GBL is divided into two pipelines which respectively enter the first tail gas absorption tower and a second tail gas absorption tower for absorption of monomethylamine in the tail gas, and the tail gas absorbed by the first tail gas absorption tower enters the second tail gas absorption tower for absorption again; the tail gas absorbed by the second tail gas absorption tower enters a tail gas washing tower for washing, organic matters in the tail gas are absorbed by the washing tower, byproduct water is discharged from a tower kettle of a methylamine recovery tower and enters the tail gas washing tower after being cooled, the tail gas is discharged into the atmosphere after being washed by the tail gas washing tower, and wastewater generated in the tail gas washing tower is discharged into a sewage treatment station for treatment. The method effectively recovers the tail gas generated in the NMP device, and reduces the sewage treatment cost and the methylamine unit consumption of the NMP device.

Inventors

  • DENG YAO
  • JIANG XIAOQIANG
  • DING SHUO
  • ZHANG LIJUAN

Assignees

  • 重庆中润新材料股份有限公司

Dates

Publication Date
20260505
Application Date
20260126

Claims (8)

  1. 1. A tail gas treatment method of an NMP production device is characterized by comprising the following steps: The tail gas is discharged into a first tail gas absorption tower (1) for absorption, GBL from a GBL rectifying device is divided into two pipelines, the two pipelines respectively enter the first tail gas absorption tower (1) and a second tail gas absorption tower (3) for absorbing monomethylamine in the tail gas, and the tail gas after the monomethylamine is absorbed by the first tail gas absorption tower (1) enters the second tail gas absorption tower (3) for absorption again; the tail gas absorbed by the second tail gas absorption tower (3) enters a tail gas washing tower (5) for washing, and organic matters in the tail gas are absorbed by the washing tower, the byproduct water is discharged from the tower kettle of the methylamine recovery tower and enters the tail gas washing tower (5) after being cooled; The tail gas after being washed by the tail gas washing tower (5) is discharged into the atmosphere after passing through the demister (7) and the photocatalytic oxidation device (8), and the waste water generated in the tail gas washing tower (5) is discharged into a sewage treatment station for treatment.
  2. 2. A method for treating an exhaust gas of an NMP production apparatus according to claim 1, wherein the two lines are respectively controlled in flow rate by regulating valves so that the ratio of the flow rates into the first exhaust gas absorption tower (1) and the second exhaust gas absorption tower (3) is 2:1.
  3. 3. The method for treating the tail gas of the NMP production device according to claim 1, wherein a first cooler (2) is connected to a pipeline connected with the second tail gas absorption tower (3), and the first cooler (2) cools GBL to enable the GBL temperature to be less than or equal to 20 ℃.
  4. 4. The method for treating the tail gas of the NMP production device according to claim 1, wherein the first tail gas absorption tower (1) and the second tail gas absorption tower (3) are respectively provided with two layers of fillers so that liquid phase and gas phase are fully contacted, and the two pipelines are respectively divided into two branch pipes which enter the upper ends of the two layers of fillers and enter the tower after passing through a distributor.
  5. 5. The method for treating the tail gas of the NMP production device according to claim 1, wherein a gas phase outlet of the second tail gas absorption tower (3) is connected with a second cooler (4), the gas phase temperature is controlled to be less than or equal to 10 ℃, and part of GBL carried away in the tail gas is condensed.
  6. 6. The method for treating the tail gas of the NMP production device according to claim 5, wherein the GBL absorbed by the first tail gas absorption tower (1) and the second tail gas absorption tower (3) automatically flows into the GBL overhead tank, and the GBL condensed by the second cooler (4) is conveyed to the GBL overhead tank.
  7. 7. The method for treating the tail gas of the NMP production device according to claim 1, wherein the byproduct water discharged from the tower bottom of the methylamine recovery tower is cooled by a third cooler (6), the third cooler (6) firstly uses circulating water to cool the byproduct water to be less than or equal to 40 ℃, and then uses chilled water to cool the byproduct water to be less than or equal to 25 ℃.
  8. 8. The method for treating the tail gas of the NMP production device according to claim 1, wherein the tail gas water scrubber (5) adopts two layers of fillers to enable a liquid phase to be fully contacted with a gas phase, and the upper and lower sections of byproduct water enter the two layers of fillers according to the proportion of 1:1.

Description

Tail gas treatment method for NMP production device Technical Field The invention belongs to the technical field of tail gas treatment, and particularly relates to a tail gas treatment method of an NMP production device. Background NMP is mainly synthesized by GBL and monomethylamine reaction, and in the production process, because monomethylamine has a low boiling point, and the deamination tower and the dehydration tower of the NMP device are negative pressure rectifying towers, monomethylamine can enter a tail gas system under the action of a vacuum pump, so that the monomethylamine content in the tail gas is high, and on-site tail gas treatment is difficult. Aiming at the tail gas treatment of the NMP device, the conventional mode is water absorption mode treatment, but because water generated by NMP synthesis is smaller, the water generated by reaction does not meet the water quantity absorbed by the tail gas, so that the water quantity absorbed by the tail gas is increased by adding industrial water, the tail gas is discharged after reaching the standard, and the absorbed water enters a sewage system for treatment. The absorbed sewage is discharged into a sewage treatment station, and because the monomethylamine belt is difficult to treat, the sewage treatment time is long, and an auxiliary reagent is added for treatment, so that the sewage treatment cost is increased. Therefore, the conventional tail gas treatment method not only increases the industrial water consumption and the sewage discharge amount, but also increases the sewage treatment cost, and because the monomethylamine enters a sewage system, the unit consumption of the monomethylamine is increased, and the sewage treatment difficulty is also improved. Disclosure of Invention The invention aims to provide a tail gas treatment method for an NMP production device, which is used for effectively recovering tail gas generated in the NMP device and reducing sewage treatment cost and methylamine unit consumption of the NMP device. In order to achieve the purpose, the technical scheme of the invention is that the tail gas treatment method of the NMP production device comprises the following steps: The tail gas is discharged into a first tail gas absorption tower for absorption, GBL from the GBL rectifying device is divided into two pipelines and respectively enters the first tail gas absorption tower and a second tail gas absorption tower for absorption of monomethylamine in the tail gas, and the tail gas after the monomethylamine is absorbed by the first tail gas absorption tower enters the second tail gas absorption tower again for absorption; the tail gas absorbed by the second tail gas absorption tower enters a tail gas washing tower for washing, and organic matters in the tail gas are absorbed by the washing tower, the byproduct water is discharged through a tower kettle of a methylamine recovery tower and enters the tail gas washing tower after being cooled; and after the tail gas is washed by the tail gas washing tower, the tail gas is discharged into the atmosphere after passing through the demister and the photocatalytic oxidation device, and the waste water generated in the tail gas washing tower is discharged into a sewage treatment station for treatment. Further, the two pipelines respectively control the flow by using the regulating valve, so that the flow ratio of the first tail gas absorption tower to the second tail gas absorption tower is 2:1. Further, a first cooler is connected to a pipeline connected with the second tail gas absorption tower, and the first cooler cools the GBL so that the GBL temperature is less than or equal to 20 ℃. Furthermore, the first tail gas absorption tower and the second tail gas absorption tower are respectively provided with two layers of fillers to enable the liquid phase and the gas phase to be fully contacted, and the two pipelines are respectively divided into two branch pipes to enter the upper ends of the two layers of fillers and enter the tower after passing through the distributor. Further, a gas phase outlet of the second tail gas absorption tower is connected with a second cooler, the gas phase temperature is controlled to be less than or equal to 10 ℃, and part of GBL carried away in the tail gas is condensed. Further, GBL after being absorbed by the first tail gas absorption tower and the second tail gas absorption tower automatically flows into the GBL overhead tank, and GBL condensed by the second cooler is conveyed to the GBL overhead tank. Further, the byproduct water discharged from the tower bottom of the methylamine recovery tower is cooled by a third cooler, the third cooler firstly uses circulating water to cool the byproduct water to be less than or equal to 40 ℃, and then uses chilled water to cool the byproduct water to be less than or equal to 25 ℃. Further, the tail gas water scrubber adopts two layers of fillers to enable the liquid phase to be fully contacted with the g