阅读说明：本技术 一种dmf生产装置尾气处理系统及工艺与应用 (Tail gas treatment system of DMF (dimethyl formamide) production device, process and application ) 是由 王存申 王德民 刘玉伟 侯国斌 孙兆辉 蔡振泉 许瑞龙 于 2021-10-27 设计创作，主要内容包括：本发明涉及甲胺DMF(二甲基甲酰胺)联产领域,尤其涉及一种DMF生产装置尾气处理系统及工艺与应用。所述工艺包括如下步骤：DMF放空尾气不输送至甲胺尾气吸收塔净化处理,而是进入DMF甲醇吸收塔,吸收放空尾气中含有的少量DMF和二甲胺。吸收完放空尾气的甲醇返回甲醇槽缓冲,以稳定的流量进入DMF合成塔进行回收使用。放空尾气通过DMF甲醇吸收塔会夹带出少量甲醇,夹带少量甲醇的放空尾气进入水洗塔,吸收放空尾气中夹带的少量甲醇。吸收完放空尾气的脱盐水返回甲胺甲醇回收塔,将夹带出的少量甲醇回收使用。本发明的技术方案解决了甲胺DMF联产装置设备腐蚀的问题,降低设备运行中腐蚀泄漏的隐患,延长装置运行周期。(The invention relates to the field of coproduction of methylamine DMF (dimethyl formamide), and particularly relates to a tail gas treatment system of a DMF production device, a process and application. The process comprises the following steps: and the DMF emptying tail gas is not conveyed to a methylamine tail gas absorption tower for purification treatment, but enters a DMF methanol absorption tower to absorb a small amount of DMF and dimethylamine contained in the emptying tail gas. And the methanol absorbing the air tail gas returns to a methanol tank for buffering, and enters the DMF synthesis tower at a stable flow rate for recycling. And the vent tail gas passes through the DMF methanol absorption tower and carries a small amount of methanol, and the vent tail gas carrying a small amount of methanol enters the water washing tower to absorb the small amount of methanol carried in the vent tail gas. And returning the desalted water absorbing the tail gas of the air to the methylamine methanol recovery tower, and recovering a small amount of methanol carried out. The technical scheme of the invention solves the problem of corrosion of equipment of the methylamine DMF co-production device, reduces the hidden danger of corrosion leakage in the operation of the equipment and prolongs the operation period of the device.)

1. The tail gas treatment system of the DMF production device is characterized by comprising: the system comprises a DMF synthesis tower, a filtering device, a vapor-liquid separator, a primary distillation tower, a rectification tower, a stripping tower, a DMF methanol absorption tower, a methanol tank and a water washing tower; the discharge hole of the DMF synthesis tower is connected with the feed inlet of a filtering device, the discharge hole of the filtering device is connected with the feed inlet of the evaporation gas-liquid separator, the gas outlet at the top of the evaporation gas-liquid separator is connected with the feed inlet of a primary distillation tower, the discharge hole at the bottom of the primary distillation tower is connected with the feed inlet of a rectification tower, and the discharge hole of the rectification tower is connected with the feed inlet of a stripping tower;

the tail gas outlet of the DMF synthesis tower and the tail gas outlet of the stripping tower are respectively connected with a DMF methanol absorption tower air inlet, the methanol outlet at the bottom of the DMF methanol absorption tower is connected with a methanol collecting device, a discharge hole of the methanol collecting device is connected with a feed inlet of the DMF synthesis tower, the tail gas outlet at the top of the DMF methanol absorption tower is connected with a feed inlet of a washing tower, and an exhaust port is arranged at the top of the washing tower.

2. The tail gas treatment system of a DMF production device according to claim 1, wherein the DMF synthesis tower is provided with feeding ports for carbon monoxide, dimethylamine and sodium methoxide methanol solution respectively.

3. The tail gas treatment system of a DMF production device according to claim 1, wherein the liquid outlet at the bottom of the evaporation gas-liquid separator is connected with the liquid inlet of the filtering device.

4. The DMF production plant tail gas treatment system according to claim 1, wherein the stripping column is provided with a nitrogen inlet.

5. The tail gas treatment system of a DMF production device according to claim 1, wherein the light component outlet at the top of the preliminary distillation tower is connected with the feeding hole of the light component recovery tower.

6. The tail gas treatment system of a DMF production device according to claim 1, wherein a discharge port at the bottom of the stripping tower is connected with a DMF finished product storage tank.

7. The tail gas treatment system of a DMF production device as claimed in claim 1, wherein a discharge port at the bottom of the washing tower is connected with a washing tank, and a liquid outlet of the washing tank is respectively connected with a liquid inlet of the washing tower and a liquid inlet of the methylamine methanol recovery tower.

8. A tail gas treatment process of a DMF production device is characterized by comprising the following steps:

carrying out gas-liquid contact on carbon monoxide, dimethylamine, sodium methoxide methanol solution and methanol in a DMF synthesis tower, and carrying out acylation reaction to obtain crude DMF liquid containing methanol, dimethylamine and sodium methoxide;

carrying out solid-liquid separation, evaporation gas-liquid separation and primary distillation, rectification and steam stripping on the crude DMF liquid to obtain qualified DMF liquid;

emptying tail gas generated by a DMF synthesis tower and a stripping tower enters a DMF methanol absorption tower to absorb DMF and dimethylamine; and then entering a water washing tower to absorb the methanol, and emptying to obtain the methanol-methanol-methanol fuel.

9. The tail gas treatment process of a DMF production device as defined in claim 8 is characterized in that the methanol content in the crude DMF liquid is 3-5%.

10. A methylamine/DMF co-production system, comprising: the DMF production plant off-gas treatment system of any one of claims 1 to 7.

Technical Field

The invention relates to the technical field of methylamine DMF (dimethyl formamide) co-production, in particular to a DMF tail gas treatment process for reducing corrosion of methylamine DMF (dimethyl formamide) co-production equipment, and a device and application thereof.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

Methylamine is an important chemical raw material. It is widely used in various departments of national economy, and is a basic raw material for the industries of pesticide, medicine, rubber, tanning, synthetic dye, synthetic resin, chemical fiber, solvent, surfactant, dye, photographic material and the like. The production method of methylamine includes several kinds, but at present, the method generally adopted at home and abroad is the methanol gas-phase catalytic ammoniation process, the methanol ammoniation process uses methanol and ammonia as raw materials, and under the action of catalyst and according to a certain proportion, the methanol ammoniation process can obtain mono-, di-and trimethylamine at the same time, and has a series of reactions:

(1)

(2)

(3)

dimethylamine is produced in the most proportion in mixed amine, but the market demand of dimethylamine is limited, and domestic methylamine manufacturers generally produce DMF (dimethyl formamide) by taking dimethylamine as a raw material, so that the coproduction of methylamine and DMF (dimethyl formamide) is realized, the production scale is enlarged, and the industrial chain is prolonged. In the production of DMF (dimethyl formamide), anhydrous dimethylamine and CO are used as raw materials, and a sodium methoxide methanol liquid is used as a catalyst at a certain temperature and under a certain pressure to carry out gas-liquid contact to complete an acylation reaction, so that the DMF (dimethyl formamide) is generated.

The reaction is actually completed in two steps:

the first step is as follows: CH (CH)₃OH+CO→HCOOCH₃

The second step is that: HCOOCH₃+(CH₃)₂NH→HCON(CH₃)₂+CH₃OH

The general reaction formula is as follows: CO + (CH)₃)₂NH→HCON(CH₃)₂+Q

Wherein Q represents heat, the reaction is exothermic.

However, the inventor finds that: a part of vent tail gas is generated in the process of synthesizing and purifying DMF, the vent tail gas is conveyed to a methylamine tail gas absorption tower to absorb organic matters of the vent tail gas and then is vented on site, and the part of vent gas contains a small amount of water, dimethylamine and DMF (dimethylformamide). At high temperature, alkaline and H₂In the presence of O, DMF (dimethyl formamide) is hydrolyzed to generate formic acid, and the corrosivity of the formic acid is enhanced at high temperature, so that methylamine production equipment is corroded and damaged.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a DMF tail gas treatment process for reducing corrosion of methylamine DMF co-production equipment, a device thereof and application thereof.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

in a first aspect of the present invention, there is provided a DMF production apparatus tail gas treatment system, comprising: the system comprises a DMF synthesis tower, a filtering device, a vapor-liquid separator, a primary distillation tower, a rectification tower, a stripping tower, a DMF methanol absorption tower, a methanol tank and a water washing tower; the discharge hole of the DMF synthesis tower is connected with the feed inlet of a filtering device, the discharge hole of the filtering device is connected with the feed inlet of the evaporation gas-liquid separator, the gas outlet at the top of the evaporation gas-liquid separator is connected with the feed inlet of a primary distillation tower, the discharge hole at the bottom of the primary distillation tower is connected with the feed inlet of a rectification tower, and the discharge hole of the rectification tower is connected with the feed inlet of a stripping tower;

the tail gas outlet of the DMF synthesis tower and the tail gas outlet of the stripping tower are respectively connected with a DMF methanol absorption tower air inlet, the methanol outlet at the bottom of the DMF methanol absorption tower is connected with a methanol collecting device, a discharge hole of the methanol collecting device is connected with a feed inlet of the DMF synthesis tower, the tail gas outlet at the top of the DMF methanol absorption tower is connected with a feed inlet of a washing tower, and an exhaust port is arranged at the top of the washing tower.

In a second aspect of the present invention, there is provided a process for treating tail gas from a DMF production apparatus, comprising:

carrying out gas-liquid contact on carbon monoxide, dimethylamine, sodium methoxide methanol solution and methanol in a DMF synthesis tower, and carrying out acylation reaction to obtain crude DMF liquid containing methanol, dimethylamine and sodium methoxide;

carrying out solid-liquid separation, evaporation gas-liquid separation and primary distillation, rectification and steam stripping on the crude DMF liquid to obtain qualified DMF liquid;

emptying tail gas generated by a DMF synthesis tower and a stripping tower enters a DMF methanol absorption tower to absorb DMF and dimethylamine; and then entering a water washing tower to absorb the methanol, and emptying to obtain the methanol-methanol-methanol fuel.

In a third aspect of the present invention, there is provided a methylamine/DMF co-production system, comprising: the tail gas treatment system of the DMF production device.

The invention has the beneficial effects that:

(1) in the traditional methylamine DMF co-production process, DMF emptying tail gas is conveyed to a methylamine tail gas absorption tower, organic matters in the emptying tail gas are absorbed and then emptied on site, and the emptying tail gas not only contains methanol and dimethylamine, but also contains a small amount of methanol and dimethylamineDMF. At high temperature, alkaline and H₂In the presence of O, DMF is hydrolyzed to generate formic acid, and the corrosivity of the formic acid is enhanced at high temperature, so that methylamine production equipment is corroded and damaged. Therefore, the invention adopts the DMF methanol absorption tower to absorb a small amount of DMF in the DMF emptying tail gas, and the methanol after absorbing the DMF is returned to the DMFDMF synthesis tower for recycling, thereby solving the problem of corrosion damage of methylamine production equipment caused by the DMF returning to a methylamine system.

(2) According to the invention, through the two-stage absorption of the DMF methanol absorption tower and the water washing tower, methanol carried by the discharged tail gas through the DMF methanol absorption tower is absorbed by desalted water, so that the content of the methanol carried by the discharged tail gas is reduced, and the desalted water after methanol absorption is returned to the methylamine methanol recovery tower for recycling, so that the consumption of the methanol is reduced.

(3) Compared with the existing mode of condensation and absorption, the invention has the advantages that the gas phase at the top of the DMF synthesis tower and the gas phase at the top of the stripping tower directly enter the DMF methanol absorption tower, condensation treatment is not needed, and methanol carried by tail gas can be recycled. The operation method is simple, low in cost, universal and easy for large-scale production.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

Fig. 1 is a schematic structural diagram of a device for reducing total nitrogen in methylamine wastewater in the embodiment of the invention.

The designations in the above figures represent respectively: 1-DMF synthesis tower, 2-filter, 3-evaporation gas-liquid separator, 4-primary distillation tower, 5-rectifying tower, 6-stripping tower, 7-DMF methanol absorption tower, 8-methanol tank, 9-water washing tower and 10-water washing tank;

wherein, A is a dimethylamine pipeline, B is a sodium methoxide methanol solution pipeline, C is a carbon monoxide pipeline, and D is a nitrogen pipeline.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

As described above, in the conventional co-production process of methylamine and DMF, the DMF vented tail gas is conveyed to a methylamine tail gas absorption tower to absorb organic matters in the vented tail gas and then is vented on site, and the vented tail gas contains methanol, dimethylamine and a small amount of DMF. At high temperature, alkaline and H₂In the presence of O, DMF is hydrolyzed to generate formic acid, and the corrosivity of the formic acid is enhanced at high temperature, so that methylamine production equipment is corroded and damaged.

In a first aspect of the present invention, there is disclosed an apparatus for recycling DMF discharged tail gas, which does not return to a methylamine production system, and comprises: the device comprises a DMF synthesis tower, a filter, a vapor-liquid separator, a primary distillation tower, a rectifying tower, a stripping tower, a DMF methanol absorption tower, a methanol tank, a water washing tower and a water washing tank, so that the recycling of the DMF emptying tail gas is realized.

A dimethylamine inlet, a carbon monoxide inlet, a sodium methoxide methanol solution inlet and a methanol inlet are formed in the DMF synthesis tower; the bottom of the filter is provided with a discharge port for discharging the filtered salt mud; a heavy component discharge port is formed in the bottom of the rectifying tower to discharge heavy components in the DMF; a nitrogen inlet is formed at the bottom of the stripping tower to blow off residual dimethylamine in the DMF; the bottom of the stripping tower is provided with a discharge port to discharge qualified DMF; and the top of the water washing tower is provided with a discharge port to discharge the emptying tail gas after absorption and purification.

And the outlet of the DMF synthesis tower is connected with the inlet of the filter. Namely, the materials in the DMF synthesis tower enter a filter to filter the salty mud in the crude DMF.

The outlet of the filter is connected with the inlet of the evaporation gas-liquid separator. Namely, the crude DMF filtered from the salt mud by the filter enters an evaporation gas-liquid separator for gas-liquid separation.

And the outlet at the bottom of the evaporation gas-liquid separator is connected with the inlet of the filter. Namely, the liquid phase material in the evaporation gas-liquid separator is circularly returned to the evaporation gas-liquid separator after salt mud is filtered by a filter, and the salt mud in the crude DMF is circularly removed.

And an outlet at the top of the evaporation gas-liquid separator is connected with an inlet of the primary distillation tower. Namely, the gas-phase material evaporated in the evaporation gas-liquid separator enters the preliminary distillation tower.

And an outlet at the bottom of the primary distillation tower is connected with an inlet of the rectification tower. Namely, crude DMF from which light components are removed after rectification and separation in a primary distillation tower enters a rectification tower.

And an outlet at the top of the rectifying tower is connected with an inlet of the stripping tower. Namely, the DMF from which the heavy components are removed after the rectification and separation by the rectifying tower enters the stripping tower.

And a gas phase inlet at the bottom of the DMF methanol absorption tower is connected with a gas phase outlet at the top of the DMF synthesis tower and a gas phase outlet at the top of the stripping tower. Namely, the vent tail gas of the DMF synthesis tower and the stripping tower enters a DMF methanol absorption tower to absorb DMF and dimethylamine contained in the vent tail gas.

The inlet of the methanol tank is connected with the outlet at the bottom of the DMF methanol absorption tower, and the outlet of the methanol tank is connected with the liquid phase inlet at the top of the DMF methanol absorption tower. Namely, methanol in the methanol tank enters the DMF methanol absorption tower through the circulating pump to absorb the emptied tail gas and then circularly enters the methanol tank, and the methanol is used to absorb DMF and dimethylamine in the emptied tail gas.

And the outlet of the methanol tank is connected with the methanol inlet of the DMF synthesis tower. Namely, the methanol in the methanol tank absorbs DMF and dimethylamine in the emptying tail gas and then enters the DMF synthesis tower through the pressure pump, and the methanol absorbs the DMF and dimethylamine in the emptying tail gas and then is recycled.

And a gas phase inlet at the bottom of the water washing tower is connected with a gas phase outlet at the top of the DMF-methanol absorption tower. Namely, the vent tail gas after absorption and purification in the DMF methanol absorption tower enters a water washing tower to absorb methanol contained in the vent tail gas.

The inlet of the rinsing bath is connected with the outlet at the bottom of the rinsing bath, and the outlet of the rinsing bath is connected with the liquid phase inlet at the top of the rinsing bath. Namely, desalted water in the rinsing tank enters the rinsing tower through the circulating pump to absorb the vent tail gas and then circularly enters the rinsing tank, and the desalted water is used for absorbing methanol in the vent tail gas.

And the outlet of the rinsing bath is connected with the inlet of the methylamine methanol recovery tower. Namely, desalted water in the rinsing bath absorbs methanol in the emptying tail gas and then enters a methylamine methanol recovery tower through a circulating pump, and the methanol carried by the DMF tail gas enters the methylamine methanol recovery tower for recovery.

The second aspect of the invention discloses a process for recycling DMF emptying tail gas in a DMF production system without returning to a methylamine production system, which comprises the following steps:

introducing carbon monoxide, dimethylamine, sodium methoxide methanol solution and methanol into a DMF synthesis tower for gas-liquid contact, and carrying out acylation reaction to obtain crude DMF liquid containing methanol, dimethylamine and sodium methoxide.

And (3) feeding the crude DMF solution after the synthesis reaction into a filter, and filtering sodium methoxide salt mud in the crude DMF solution through a filter plate of the filter.

And (3) feeding the crude DMF liquid after filtering the sodium methoxide salt mud into a evaporation gas-liquid separator for evaporation separation, feeding the liquid phase material in the evaporation gas-liquid separator into a filter through forced circulation, filtering the sodium methoxide salt mud in the DMF liquid through a filter plate of the filter, and returning the filtered liquid phase material to the evaporation gas-liquid separator.

And (3) feeding the gas-phase material separated by evaporating the crude DMF liquid in the evaporation gas-liquid separator into a primary distillation tower, and rectifying the gas-phase material in the primary distillation tower to remove light components (methanol, dimethylamine, water and a small amount of DMF) in the crude DMF liquid.

And (3) the crude DMF liquid with light components removed after the rectification by the primary distillation tower enters a rectification tower, and heavy components (DMAC and MMF) in the crude DMF liquid are removed after the rectification by the rectification tower.

And the DMF liquid which is rectified by the rectifying tower and is removed with heavy components enters a stripping tower, and residual dimethylamine in the DMF liquid is blown off by nitrogen.

And (4) extracting the qualified DMF liquid treated by the stripping tower into a DMF finished product storage tank.

And feeding the emptying tail gas of the DMF synthesis tower and the emptying tail gas of the stripping tower into a DMF methanol absorption tower to absorb a small amount of DMF and dimethylamine contained in the emptying tail gas. And the methanol absorbing the air tail gas returns to a methanol tank for buffering, and enters the DMF synthesis tower at a stable flow rate for recycling.

And the vent tail gas passes through the DMF methanol absorption tower and carries a small amount of methanol, and the vent tail gas carrying a small amount of methanol enters the water washing tower to absorb the small amount of methanol carried in the vent tail gas. And returning the desalted water absorbing the tail gas of the air to the methylamine methanol recovery tower, and recovering a small amount of methanol carried out.

The present invention is described in further detail below with reference to specific examples, which are intended to be illustrative of the invention and not limiting.

First embodiment

Referring to FIG. 1, a DMF blowdown offgas is not returned to the methylamine production system, but is recycled in the DMF production system. The method comprises the following steps: the device comprises a DMF synthesis tower, a filter, a vapor-liquid separator, a primary distillation tower, a rectifying tower, a stripping tower, a DMF methanol absorption tower, a methanol tank, a water washing tower and a water washing tank, so that the recycling of the DMF emptying tail gas is realized.

A dimethylamine inlet, a carbon monoxide inlet, a sodium methoxide methanol solution inlet and a methanol inlet are formed in the DMF synthesis tower; the bottom of the filter is provided with a discharge port for discharging the filtered salt mud; a heavy component discharge port is formed in the bottom of the rectifying tower to discharge heavy components in the DMF; a nitrogen inlet is formed at the bottom of the stripping tower to blow off residual dimethylamine in the DMF; the bottom of the stripping tower is provided with a discharge port to discharge qualified DMF; and the top of the water washing tower is provided with a discharge port to discharge the emptying tail gas after absorption and purification.

And the outlet of the DMF synthesis tower is connected with the inlet of the filter. Namely, the materials in the DMF synthesis tower enter a filter to filter the salty mud in the crude DMF.

The outlet of the filter is connected with the inlet of the evaporation gas-liquid separator. Namely, the crude DMF filtered from the salt mud by the filter enters an evaporation gas-liquid separator for gas-liquid separation.

And the outlet at the bottom of the evaporation gas-liquid separator is connected with the inlet of the filter. Namely, the liquid phase material in the evaporation gas-liquid separator is circularly returned to the evaporation gas-liquid separator after salt mud is filtered by a filter, and the salt mud in the crude DMF is circularly removed.

And an outlet at the top of the evaporation gas-liquid separator is connected with an inlet of the primary distillation tower. Namely, the gas-phase material at the evaporation position in the evaporation gas-liquid separator enters the preliminary distillation tower.

And an outlet at the bottom of the primary distillation tower is connected with an inlet of the rectifying tower. Namely, crude DMF from which light components are removed after rectification and separation in a primary distillation tower enters a rectification tower.

And an outlet at the top of the primary distillation tower is connected with an inlet of the light component recovery tower. Namely, the light component separated by the primary distillation tower enters a light component recovery tower.

And an outlet at the top of the rectifying tower is connected with an inlet of the stripping tower. Namely, the DMF from which the heavy components are removed after the rectification and separation by the rectifying tower enters the stripping tower.

And a gas phase inlet at the bottom of the DMF methanol absorption tower is connected with a gas phase outlet at the top of the DMF synthesis tower and a gas phase outlet at the top of the stripping tower. Namely, the vent tail gas of the DMF synthesis tower and the stripping tower enters a DMF methanol absorption tower to absorb DMF and dimethylamine contained in the vent tail gas.

The inlet of the methanol tank is connected with the outlet at the bottom of the DMF methanol absorption tower, and the outlet of the methanol tank is connected with the liquid phase inlet at the top of the DMF methanol absorption tower. Namely, methanol in the methanol tank enters the DMF methanol absorption tower through the circulating pump to absorb the emptied tail gas and then circularly enters the methanol tank, and the methanol is used to absorb DMF and dimethylamine in the emptied tail gas.

And the outlet of the methanol tank is connected with the methanol inlet of the DMF synthesis tower. Namely, the methanol in the methanol tank absorbs DMF and dimethylamine in the emptying tail gas and then enters the DMF synthesis tower through the pressure pump, and the methanol absorbs the DMF and dimethylamine in the emptying tail gas for recycling.

And a gas phase inlet at the bottom of the water washing tower is connected with a gas phase outlet at the top of the DMF-methanol absorption tower. Namely, the vent tail gas after absorption and purification in the DMF methanol absorption tower enters a water washing tower to absorb methanol contained in the vent tail gas.

The inlet of the rinsing bath is connected with the outlet at the bottom of the rinsing bath, and the outlet of the rinsing bath is connected with the liquid phase inlet at the top of the rinsing bath. Namely, desalted water in the rinsing tank enters the rinsing tower through the circulating pump to absorb the vent tail gas and then circularly enters the rinsing tank, and the desalted water is used for absorbing methanol in the vent tail gas.

And the outlet of the rinsing bath is connected with the inlet of the methylamine methanol recovery tower. Namely, after the desalted water in the water washing tank absorbs methanol in the discharged tail gas, the methanol enters a methylamine methanol recovery tower through a circulating pump, and the methanol carried out by the DMF tail gas enters the methylamine methanol recovery tower for recovery.

Second embodiment

A process for recycling DMF emptying tail gas in a DMF production system without returning to a methylamine production system is carried out by adopting a device shown in the attached figure 1, and comprises the following steps:

introducing carbon monoxide, dimethylamine, sodium methoxide methanol solution and methanol into a DMF synthesis tower for gas-liquid contact, and performing acylation reaction to obtain crude DMF liquid containing methanol, dimethylamine and sodium methoxide, wherein the content of methanol in the crude DMF liquid is controlled to be 3-5%.

And (3) feeding the crude DMF solution after the synthesis reaction into a filter, and filtering sodium methoxide salt mud in the crude DMF solution through a filter plate of the filter.

And (3) feeding the crude DMF liquid after filtering the sodium methoxide salt mud into a evaporation gas-liquid separator for evaporation separation, feeding the liquid phase material in the evaporation gas-liquid separator into a filter through forced circulation, filtering the sodium methoxide salt mud in the DMF liquid through a filter plate of the filter, and returning the filtered liquid phase material to the evaporation gas-liquid separator. The sodium methoxide salt mud in the crude DMF solution is filtered off by continuous circulation.

And (3) feeding the gas-phase material separated by evaporating the crude DMF liquid in the evaporation gas-liquid separator into a primary distillation tower, and removing light components (methanol, dimethylamine, water and a small amount of DMF) in the crude DMF liquid from the tower top after rectification in the primary distillation tower.

And (3) feeding the crude DMF liquid with light components removed after the crude DMF liquid is rectified by the primary distillation tower into a rectification tower, and removing heavy components (DMAC and MMF) in the crude DMF liquid from the tower kettle after the crude DMF liquid is rectified by the rectification tower.

And the DMF liquid with the heavy components removed after rectification in the rectifying tower enters a stripping tower, residual dimethylamine in the DMF liquid is blown off by nitrogen, and a qualified dimethylamine finished product is obtained at the bottom of the tower.

And feeding the emptying tail gas of the DMF synthesis tower and the emptying tail gas of the stripping tower into a DMF methanol absorption tower to absorb a small amount of DMF and dimethylamine contained in the emptying tail gas. And the methanol absorbing the air tail gas returns to a methanol tank for buffering, and enters the DMF synthesis tower at a stable flow rate for recycling.

And the vent tail gas passes through the DMF methanol absorption tower and carries a small amount of methanol, and the vent tail gas carrying a small amount of methanol enters the water washing tower to absorb the small amount of methanol carried in the vent tail gas. And returning the desalted water absorbing the tail gas of the air to the methylamine methanol recovery tower, and recovering a small amount of methanol carried out.

It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications and equivalents can be made in the technical solutions described in the foregoing embodiments, or equivalents thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.