阅读说明：本技术 一种生产高纯度甲缩醛的方法 (Method for producing high-purity methylal ) 是由 杨骁� 张学清 张德贵 王海成 华学焱 于 2019-11-06 设计创作，主要内容包括：一种生产高纯度甲缩醛的方法,步骤一：甲缩醛杂质吸附：甲缩醛罐含有杂质的甲缩醛进入A管线,A管线对甲缩醛进行加热汽化后泵入甲缩醛精制塔,甲缩醛蒸汽与从甲缩醛精制塔上部进入的吸收剂进行汽-液逆向接触；步骤二：吸收剂回收：吸收后的吸收剂从甲缩醛精制塔底部流出,经B管线进行加热后从上部泵入吸收剂抽提塔,吸收剂与从吸收剂抽提塔下部进入的低露点低压惰性气体进行液-气逆向接触。本发明根据不同的工艺条件可以获得不同纯度的甲缩醛,工艺简单,耗能较少,具有安全、适用等特点,有很好的推广和实用价值,广泛的推广应用后会产生良好的经济效益。(A method for producing high-purity methylal comprises the following steps: adsorbing methylal impurities: the methylal containing impurities in the methylal tank enters an A pipeline, the A pipeline heats and vaporizes the methylal and then pumps the methylal into a methylal refining tower, and the methylal steam is in reverse vapor-liquid contact with an absorbent entering from the upper part of the methylal refining tower; step two: and (3) recovering the absorbent: the absorbed absorbent flows out from the bottom of the methylal refining tower, is heated by a pipeline B and then is pumped into an absorbent extraction tower from the upper part, and the absorbent is in liquid-gas reverse contact with low dew point and low pressure inert gas entering from the lower part of the absorbent extraction tower. The invention can obtain methylal with different purities according to different process conditions, has the characteristics of simple process, less energy consumption, safety, applicability and the like, has good popularization and practical values, and can generate good economic benefits after wide popularization and application.)

1. A method for producing high-purity methylal is characterized by comprising the following steps:

the method comprises the following steps: adsorbing methylal impurities: the methylal tank (3) is filled with impurities, the methylal is heated and vaporized by the A pipeline and then pumped into the methylal refining tower (1), methylal vapor is in vapor-liquid reverse contact with an absorbent entering from the upper part of the methylal refining tower (1), methanol, water and part of methylal in the methylal are absorbed by the absorbent, and the methylal is subjected to absorption and purification by the absorbent and then sequentially condensed, collected, pumped and packaged by a pipeline D arranged at the top of the methylal refining tower (1);

step two: and (3) recovering the absorbent: the absorbed absorbent flows out from the bottom of the methylal refining tower (1), is heated through a pipeline B and then is pumped into the absorbent extraction tower (2) from the upper part, the absorbent is in liquid-gas reverse contact with low dew point and low pressure inert gas entering from the lower part of the absorbent extraction tower (2), methylal, methanol and water enter a vapor phase, the water content of the absorbent is reduced after the liquid phase absorbent is extracted by the inert gas, the absorbent is regenerated, and the regenerated absorbent is heated through a pipeline C at the bottom of the absorbent extraction tower (2) and then is pumped into the methylal refining tower (1) for reutilization.

2. The process for producing high-purity methylal according to claim 1, wherein: the absorption agent extraction tower (2) is extracted with vapor-phase acetal, methanol and water, and the vapor-phase acetal, methanol and water enter a methylal tank (3) after being condensed, rectified and condensed again in sequence through an E pipeline.

3. The process for producing high-purity methylal according to claim 2, wherein: the E line comprises a first condenser (E5), a methylal recovery column (C3) and a second condenser (E7) arranged in series along the line flow direction.

4. The process for producing high-purity methylal according to claim 3, wherein: the feed inlet of the methylal recovery tower (C3) is added with desalted water.

5. The process for producing high-purity methylal according to claim 1, wherein: and the inert gas in the second step is nitrogen, and the nitrogen is heated by a first heater (E6) and then enters the absorbent extraction tower (2).

6. The process for producing high-purity methylal according to claim 1, wherein: the A pipeline comprises a first circulating pump (P1) and a methylal vaporizer (E1) which are sequentially arranged along the flowing direction of the pipeline; the B pipeline comprises an absorbent circulating pump (P2) and an absorbent heater (E2) which are arranged in sequence along the pipeline flow direction; the C line comprises a second circulation pump (P4) and an absorbent cooler (E4) arranged in series along the line flow direction; the D line includes a third condenser (E3), a product tank (V2), and a third circulation pump (P3) arranged in series along the line flow direction.

7. The process for producing high-purity methylal according to claim 1, wherein: the absorbent is glycol, glycerol and monomethoxy polymer thereof.

8. The process for producing high-purity methylal according to claim 1, wherein: the ratio of the absorbent to the feed in the methylal refining tower (1) is 2: 1-5: 1.

9. The process for producing high-purity methylal according to any one of claims 1 to 8, wherein: and in the second step, the water content of the liquid-phase absorbent is reduced to 30ppm after the liquid-phase absorbent is extracted by inert gas.

Technical Field

The invention belongs to a method for refining methylal, and particularly belongs to a method for producing high-purity methylal.

Background

The methylal has excellent physical and chemical properties, namely good solubility, low boiling point and good water solubility, can be widely applied to products such as cosmetics, medicines, household products, industrial and automobile products, insecticide leather polishing agents, cleaning agents, rubber industry, paints, printing ink and the like, and can replace F11, F13 and chlorine-containing solvents as the cleaning agents because the methylal has good oil-removing capacity and play performance, reduce the emission of Volatile Organic Compounds (VOCs) and reduce the pollution to the atmosphere because of replacing Freon. There are many plants for producing industrial grade methylal in China, but there are few plants for producing methylal with water content less than 100 ppm. With the transformation and upgrading of the manufacturing industry, the demand of high-purity polyformaldehyde is more and more. Particularly, the molecular weight regulator used in the production of polyformaldehyde has more strict requirements on water content, and the water content is generally required to be lower than 50ppm in order to improve the product quality.

At present, the technology for producing high-purity methylal is also developed in China, and the core of the technology is to reduce the water content of the methylal to be less than 100ppm by adopting pressure swing rectification. The main determination of the process is the high energy consumption. The invention adopts the adsorption and stripping processes to reduce the water content of methylal to below 50 ppm.

Disclosure of Invention

The invention aims to provide a method for producing high-purity methylal, which aims to solve the technical problem that the energy consumption is high in the production of the high-purity methylal in the prior art; and solves the problem of low purity of methylal produced by the prior art.

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

a method for producing high-purity methylal is characterized by comprising the following steps:

the method comprises the following steps: adsorbing methylal impurities: the methylal containing impurities in the methylal tank enters a pipeline A, the pipeline A heats and vaporizes the methylal and then pumps the methylal into the methylal refining tower, methylal steam and an absorbent entering from the upper part of the methylal refining tower are in vapor-liquid reverse contact, methanol, water and part of methylal in the methylal are absorbed by the absorbent, and the methylal is subjected to absorption and purification by the absorbent and then sequentially condensed, collected, pumped and packaged through a pipeline D arranged at the top of the methylal refining tower;

step two: and (3) recovering the absorbent: the absorbed absorbent flows out from the bottom of the methylal refining tower, is heated by a pipeline B and then is pumped into an absorbent extraction tower from the upper part, the absorbent is in liquid-gas reverse contact with low dew point and low pressure inert gas entering from the lower part of the absorbent extraction tower, methylal, methanol and water enter a vapor phase, the water content of the absorbent is reduced after the liquid phase absorbent is extracted by the inert gas, the absorbent is regenerated, and the regenerated absorbent is heated by a pipeline C at the bottom of the absorbent extraction tower and then is pumped into the methylal refining tower for reuse.

Further preferably, the absorption agent extraction tower is internally extracted with vapor-phase acetal, methanol and water, and the vapor-phase acetal, methanol and water enter a methylal tank after being condensed, rectified and condensed again in sequence through an E pipeline.

Further, the E pipeline comprises a first condenser, a methylal recovery tower and a second condenser which are sequentially arranged along the pipeline flow direction.

Further, desalted water is added into a feed inlet of the methylal recovery tower.

Further, the inert gas in the second step is nitrogen, and the nitrogen is heated by the first heater and then enters the absorbent extraction tower.

Further, the A pipeline comprises a first circulating pump and a methylal vaporizer (E1) which are sequentially arranged along the flowing direction of the pipeline; the pipeline B comprises an absorbent circulating pump and an absorbent heater which are sequentially arranged along the flow direction of the pipeline; the pipeline C comprises a second circulating pump and an absorbent cooler which are sequentially arranged along the flow direction of the pipeline; the D pipeline includes along the third condenser, finished product groove and the third circulating pump that the pipeline flow direction set up in order.

Further, the absorbent is ethylene glycol, glycerol and monomethoxy polymer thereof.

In addition, the ratio of the methylal refining tower absorbent to the feeding material is 2: 1-5: 1.

More preferably, the water content of the liquid phase absorbent in the second step is reduced to 30ppm after the liquid phase absorbent is extracted by inert gas.

Compared with the prior art, the invention has the following characteristics and beneficial effects:

the invention adopts absorption and stripping process to purify methylal, adopts low-volatility and high-water-absorptivity organic matters such as glycol, glycerol and monomethoxy polymer thereof as absorbent, takes bottom dew point nitrogen as stripping gas, and prevents material deterioration; the methylal with different purities can be obtained according to different process conditions, the process is simple, the energy consumption is less, the methylal has the characteristics of safety, applicability and the like, has good popularization and practical values, and can generate good economic benefits after wide popularization and application.

Drawings

FIG. 1 is a schematic structural diagram of a methylal refining column according to the present invention;

FIG. 2 is a schematic diagram of the structure of an absorbent extraction column according to the present invention;

FIG. 3 is a schematic view showing the structure of a production system relating to a method for producing high-purity methylal according to the present invention.

Reference numerals: a 1-methylal refining column; 2-an absorbent extraction column; a 3-methylal tank; a C3-methylal recovery column; e1-methylal vaporizer; e2-absorbent heater; e3-third condenser; e4-absorbent cooler; e5-first condenser; e6 — first heater; e7-second condenser; p1-first circulation pump; p2-absorbent circulation pump; p3-third circulation pump; p4-second circulation pump; v2-product tank.

Detailed Description

In order to make the technical means, innovative features, objectives and functions realized by the present invention easy to understand, the present invention is further described below.

The examples described herein are specific embodiments of the present invention, are intended to be illustrative and exemplary in nature, and are not to be construed as limiting the scope of the invention. In addition to the embodiments described herein, those skilled in the art will be able to employ other technical solutions which are obvious based on the disclosure of the claims and the specification of the present application, and these technical solutions include technical solutions which make any obvious replacement or modification of the embodiments described herein

A method for producing high-purity methylal is characterized by comprising the following steps:

the method comprises the following steps: adsorbing methylal impurities: the methylal tank 3 enters a line A containing impurities, and as can be seen by combining the figures 1 and 3, the line A comprises a first circulating pump P1 and a methylal vaporizer E1 which are sequentially arranged along the flowing direction of the line; the pipeline B comprises an absorbent circulating pump P2 and an absorbent heater E2 which are arranged in sequence along the flow direction of the pipeline; the D pipeline comprises a third condenser E3, a finished product tank V2 and a third circulating pump P3 which are sequentially arranged along the flow direction of the pipeline, the A pipeline heats and vaporizes methylal and then pumps the methylal into the methylal refining tower 1, methylal steam and an absorbent entering from the upper part of the methylal refining tower 1 are in vapor-liquid reverse contact, methanol, water and part of methylal in the methylal are absorbed by the absorbent, and the methylal is adsorbed and purified by the absorbent and then is sequentially condensed, collected, pumped and packaged through a pipeline D arranged at the top of the methylal refining tower 1; as can be seen from fig. 2 and 3, the vapor phase acetal, methanol and water extracted from the absorbent extraction column 2 enter the methylal tank 3 after being sequentially condensed, rectified and re-condensed through the line E, the line E comprises a first condenser E5, a methylal recovery column C3 and a second condenser E7 which are sequentially arranged along the flow direction of the pipeline, and desalted water is added into the feed inlet of the methylal recovery column C3.

Step two: and (3) recovering the absorbent: the ratio of an absorbent to a feed in a methylal refining tower 1 is 2: 1-5: 1, the absorbent is ethylene glycol, glycerol and a monomethoxy polymer thereof, the absorbent after absorption flows out from the bottom of the methylal refining tower 1, the absorbent is heated by a pipeline B and then pumped into an absorbent extraction tower 2 from the upper part, the absorbent is in liquid-gas reverse contact with low dew point and low pressure inert gas entering from the lower part of the absorbent extraction tower 2, the inert gas is nitrogen, the nitrogen is heated by a first heater E6 and then enters the absorbent extraction tower 2, methylal, methanol and water enter a gas phase, the liquid absorbent is extracted by the inert gas and then has a reduced water content to 30ppm, the absorbent is regenerated, the regenerated absorbent is heated by a pipeline C at the bottom of the absorbent extraction tower 2 and then the methylal refining tower 1 is pumped for reuse, as can be seen in connection with fig. 2 and 3, the C line includes a second circulation pump P4 and an absorbent cooler E4 arranged in series along the line flow direction.