阅读说明：本技术 一种利用三氯蔗糖氯化尾气生产氯甲醚的方法 (Method for producing chloromethyl ether by using sucralose chlorination tail gas ) 是由 赵金刚 张正颂 郑健 王余杰 于 2020-05-22 设计创作，主要内容包括：本发明涉及一种利用三氯蔗糖氯化尾气生产氯甲醚的方法,包括以下步骤：a.三氯蔗糖氯化反应产生的尾气,经一级冷凝、浓硫酸脱水、加压分离后,然后冷凝至-35℃以下,得到二氧化硫液体和纯氯化氢气体；b.将氯化氢气体连续通入一级反应塔里与甲醛、甲缩醛溶液循环喷淋反应形成氯甲醚溶液；c.一级反应塔底部采出的氯甲醚溶液经连续分层后得到氯甲醚粗品；d.氯甲醚粗品经过精馏提纯后,得到纯度99.5%、水份低于100ppm的氯甲醚。本发明的优点在于：氯化氢反应效率可达95%,可以得到优质的氯甲醚产品,延伸了公司的产业链,处理后的尾气可达标排放；极大的降低了废盐酸的处理费用。(The invention relates to a method for producing chloromethyl ether by using sucralose chlorination tail gas, which comprises the following steps: a. tail gas generated in the chlorination reaction of the sucralose is subjected to primary condensation, concentrated sulfuric acid dehydration and pressure separation, and then is condensed to below-35 ℃ to obtain sulfur dioxide liquid and pure hydrogen chloride gas; b. continuously introducing hydrogen chloride gas into a first-stage reaction tower to circularly spray and react with formaldehyde and methylal solution to form chloromethyl ether solution; c. continuously layering the chloromethyl ether solution extracted from the bottom of the first-stage reaction tower to obtain a crude chloromethyl ether product; d. after the crude chloromethyl ether product is rectified and purified, the chloromethyl ether with the purity of 99.5 percent and the water content of less than 100ppm is obtained. The invention has the advantages that: the reaction efficiency of the hydrogen chloride can reach 95 percent, high-quality chloromethyl ether products can be obtained, the industrial chain of a company is extended, and the treated tail gas can reach the standard and can be discharged; greatly reduces the treatment cost of the waste hydrochloric acid.)

1. A method for producing chloromethyl ether by using sucralose chlorination tail gas is characterized by comprising the following steps:

a. condensing tail gas generated by chlorination reaction of sucralose to 1-5 ℃ to remove organic solvent trichloroethane in the tail gas, dehydrating by concentrated sulfuric acid, pressurizing the residual hydrogen chloride and sulfur dioxide gas to more than 0.6MPa, and condensing to below-35 ℃ to obtain sulfur dioxide liquid and pure hydrogen chloride gas;

b. adding a prepared formaldehyde solution and a methylal solution with the concentration of 37% into a primary reaction tower, continuously introducing the obtained hydrogen chloride gas into the primary reaction tower to circularly spray and react with the formaldehyde solution and the methylal solution to form a chloromethyl ether solution, wherein the temperature of the primary reaction tower is controlled to be 5-12 ℃, and the liquid level is controlled to be 50-70%;

c. continuously layering the chloromethyl ether solution extracted from the bottom of the first-stage reaction tower to obtain a crude chloromethyl ether product on the upper layer and dilute hydrochloric acid-containing wastewater on the lower layer;

d. rectifying and purifying the crude chloromethyl ether product at the temperature of 0-60 ℃ under normal pressure to obtain the chloromethyl ether with the purity of 99.5 percent and the water content of less than 100 ppm.

2. The method for producing chloromethyl ether using sucralose chlorination tail gas according to claim 1, wherein:

a. the residual gas phase of the first-stage reaction tower enters a second-stage reaction tower, and is subjected to circulating spray absorption reaction with a formaldehyde methylal solution with the concentration of 37% prepared in the second-stage reaction tower, the preparation temperature is controlled to be 5-12 ℃, the liquid level is controlled to be 50-70%, and a reaction liquid containing chloromethyl ether, formaldehyde and methylal obtained at the bottom of the second-stage reaction tower returns to the first-stage reaction tower to be subjected to circulating spray reaction with introduced hydrogen chloride;

b. and tail gas at the outlet of the second-stage reaction tower enters the first-stage water absorption tower and the second-stage alkali absorption tower in sequence to be absorbed and then is discharged after reaching the standard.

3. The method for producing chloromethyl ether using sucralose chlorination tail gas according to claim 1, wherein:

and (3) continuously layering the chloromethyl ether solution extracted from the bottom of the first-stage reaction tower, feeding the hydrochloric acid-containing wastewater obtained from the lower part into a distillation kettle, distilling at the normal pressure and the temperature of 30-50 ℃ to recover hydrogen chloride, and returning the recovered hydrogen chloride to the first-stage reaction tower for recycling.

4. The method for producing chloromethyl ether using sucralose chlorination tail gas according to claim 1, wherein: the liquid level of the first-stage reaction tower is preferably controlled to be 30-60%.

5. The method for producing chloromethyl ether using sucralose chlorination tail gas according to claim 1 or 2, characterized in that: the liquid level of the secondary reaction tower is preferably controlled to be 30-60%.

Technical Field

The invention belongs to the technical field of chemical production, and relates to a method for producing chloromethyl ether by using sucralose chlorination tail gas.

Background

Sucralose (Sucralose or TGS CNS: 19.016; INS: 955), also known as Sucralose, saccharan or 4,1, 6, -trichloro-4, 1, 6, -trideoxy-semimilk sucrose, the english name: Sucralose. Sucralose is prepared by taking sucrose as a raw material through esterification, chlorination and deprotection, thionyl chloride is taken as a chlorinating agent in the chlorination process of sucralose, a large amount of hydrogen chloride gas and sulfur dioxide tail gas are generated in the reaction process of the chlorination procedure, hydrogen chloride is colorless and has pungent smell, and the aqueous solution of the hydrogen chloride is commonly called hydrochloric acid and is known as hydrochloric acid. The relative molecular mass was 36.46. Hydrogen chloride is very soluble in water, and at 0 ℃,1 volume of water can dissolve about 500 volumes of hydrogen chloride.

A traditional treatment method for sucralose chlorination tail gas is to freeze and remove a small amount of organic solvent 1,1, 2-trichloroethane in the tail gas, then produce hydrochloric acid by absorbing hydrogen chloride through a three-stage falling film, sell the hydrochloric acid to printing and dyeing enterprises and metal processing enterprises, and sometimes cause the hydrochloric acid of a production system to be stored without places due to the fact that the enterprises cannot completely consume the hydrochloric acid due to a large amount of impurities.

The invention content is as follows:

the invention aims to overcome the defects caused by the treatment of sucralose chlorination tail gas into hydrochloric acid in the prior art, and provides a method for treating hydrogen chloride in chlorination tail gas in sucralose production.

The invention is realized by the following technical scheme:

a method for producing chloromethyl ether by using sucralose chlorination tail gas comprises the following steps:

a. condensing tail gas generated by chlorination reaction of sucralose to 1-5 ℃ to remove organic solvent trichloroethane in the tail gas, dehydrating by concentrated sulfuric acid, pressurizing the residual hydrogen chloride and sulfur dioxide gas to more than 0.6MPa, and condensing to below-35 ℃ to obtain sulfur dioxide liquid and pure hydrogen chloride gas;

b. adding a prepared formaldehyde solution and a methylal solution with the concentration of 37% into a primary reaction tower, continuously introducing the obtained hydrogen chloride gas into the primary reaction tower to circularly spray and react with the formaldehyde solution and the methylal solution to form a chloromethyl ether solution, wherein the temperature of the primary reaction tower is controlled to be 5-12 ℃, and the liquid level is controlled to be 50-70%;

c. continuously layering the chloromethyl ether solution extracted from the bottom of the first-stage reaction tower to obtain a crude chloromethyl ether product on the upper layer and dilute hydrochloric acid-containing wastewater on the lower layer;

d. rectifying and purifying the crude chloromethyl ether product at the temperature of 0-60 ℃ under normal pressure to obtain the chloromethyl ether with the purity of 99.5 percent and the water content of less than 100 ppm.

The further technical scheme is as follows: a. the residual gas phase of the first-stage reaction tower enters a second-stage reaction tower, and is subjected to circulating spray absorption reaction with a formaldehyde methylal solution with the concentration of 37% prepared in the second-stage reaction tower, the preparation temperature is controlled to be 5-12 ℃, the liquid level is controlled to be 50-70%, and a reaction liquid containing chloromethyl ether, formaldehyde and methylal obtained at the bottom of the second-stage reaction tower returns to the first-stage reaction tower to be subjected to circulating spray reaction with introduced hydrogen chloride; b. and tail gas at the outlet of the second-stage reaction tower enters the first-stage water absorption tower and the second-stage alkali absorption tower in sequence to be absorbed and then is discharged after reaching the standard.

The further technical scheme is as follows:

and (3) continuously layering the chloromethyl ether solution extracted from the bottom of the first-stage reaction tower, feeding the hydrochloric acid-containing wastewater obtained from the lower part into a distillation kettle, distilling at the normal pressure and the temperature of 30-50 ℃ to recover hydrogen chloride, and returning the recovered hydrogen chloride to the first-stage reaction tower for recycling.

The further technical scheme is as follows: the liquid level of the first-stage reaction tower is preferably controlled to be 30-60%.

The further technical scheme is as follows: the liquid level of the secondary reaction tower is preferably controlled to be 30-60%.

The invention has the advantages that:

the reaction efficiency for treating the hydrogen chloride can reach 95 percent; the treated tail gas can reach the standard and be discharged; the treatment cost of the waste hydrochloric acid is greatly reduced, so that the production cost is reduced, and the profit of the product is maximized; the industrial chain of a company is extended, high-quality chloromethyl ether products can be obtained, and the production cost is further reduced.

Description of the drawings:

FIG. 1 is a process flow diagram of the present invention.

The specific implementation method comprises the following steps:

example one:

as shown in figure 1, the tail gas generated by the chlorination reaction of sucralose is subjected to primary condensation (condensation to 1-5 ℃) to remove the organic solvent 1,1, 2-trichloroethane in the tail gas, then is dehydrated by concentrated sulfuric acid, the residual hydrogen chloride and sulfur dioxide gas are pressurized to 0.6MPa by a compressor, and then are sent to a freezing kettle to be condensed to-35 ℃ to obtain sulfur dioxide liquid and pure hydrogen chloride gas.

Adding the prepared formaldehyde and methylal solution into a first-stage reaction tower, continuously introducing the hydrogen chloride gas subjected to freeze separation and purification into the first-stage reaction tower, adding the prepared 37% formaldehyde and methylal solution into the first-stage reaction tower, performing circulating spray reaction to form a chloromethyl ether solution, controlling the temperature of the first-stage reaction tower to be 5-12 ℃ and controlling the liquid level to be 35%;

continuously layering the chloromethyl ether solution extracted from the bottom of the first-stage reaction tower to obtain a crude chloromethyl ether product on the upper layer and dilute hydrochloric acid-containing wastewater on the lower layer; the crude product of the upper chloromethyl ether is purified by rectification (normal pressure, 0-60 ℃) to obtain the chloromethyl ether with the purity of 99.5 percent and the water content of less than 100 ppm.

The produced liquid at the bottom of the first-stage reaction tower enters a delayer to be continuously layered, the lower-layer dilute hydrochloric acid enters a hydrogen chloride distillation kettle to be distilled (at normal pressure and 30-50 ℃) to recover hydrogen chloride, and then enters a neutralization kettle to be neutralized and discharged to sewage treatment.

The residual gas phase at the top of the first-stage reaction tower directly enters a gas phase port at the bottom of the second-stage reaction tower, 37% of prepared formaldehyde and methylal solution are added in advance at the bottom of the tower and lifted to the top of the tower by a circulating pump at the bottom of the tower for circular absorption, absorption liquid (mainly containing chloromethylether, formaldehyde and methylal solution) is sent to a material inlet of the first-stage reaction tower at a flow rate of 1.1m for flowering/h, hydrogen chloride gas enters from the gas phase port at the bottom of the first-stage reaction tower at a flow rate of 50m for flowering/h, the formaldehyde and methylal solution added in advance at the bottom of the first-stage reaction tower is lifted to the top of the tower by the circulating pump²The graphite heat exchanger cools the circulating liquid at the bottom of the tower, the temperature of the reaction tower is controlled to be 10-15 ℃, and the liquid level of the reactor is controlled to be 50%.

And tail gas at the top of the second-stage reaction tower enters a first-stage water absorption tower and a second-stage alkali absorption tower and is exhausted after reaching the standard.

Example two:

adding prepared 37% formaldehyde and methylal solution into a first-stage reaction tower, and purifying hydrogen chloride gas from chlorination tail gas and chloromethyl ether, formaldehyde and methylal solution from a second-stage reaction tower according to a molar ratio of 1.2: 0.5: 0.5 into the tower, introducing chloromethyl ether, formaldehyde and methylal solution from the second-stage reaction tower from a feeding port in the tower at a flow rate of 1.5 m/h, introducing hydrogen chloride gas from a gas phase port at the bottom of the tower at a flow rate of 60 m/h, lifting the formaldehyde and methylal solution which are pre-added at the bottom of the tower to the top of the tower by a circulating pump at the bottom of the tower for cyclic absorption, sampling and analyzing after the materials are cyclically absorbed for about 5 hours, continuously extracting, and adopting 50m for sampling and analyzing²The graphite heat exchanger cools the circulating liquid at the bottom of the tower, the temperature of the reaction tower is controlled to be 5-10 ℃, and the liquid level of the reactor is controlled to be 60%.

The gaseous phase of reaction tower top directly gets into second grade reaction tower, and 37% formaldehyde and methylal solution of preparing get into by the pan feeding mouth in the tower with 1.3 m/h, and first grade reaction tower gaseous phase gets into by the gaseous phase mouth at the bottom of the tower, and 37% formaldehyde and methylal solution of adding the preparation in advance at the bottom of the tower are promoted by the circulating pump at the bottom of the tower to the top of the tower and are circulated and absorb, then 1.5m fortune/h flow send to first grade reaction tower material entry, adopt 50m to thin a year/h flow and send to first²The graphite heat exchanger cools the circulating liquid at the bottom of the tower, the temperature of the reaction tower is controlled to be 5-10 ℃, and the liquid level of the reactor is controlled to be 70%.

And tail gas at the top of the second-stage reaction tower enters a first-stage water absorption tower and a second-stage alkali absorption tower and is exhausted after reaching the standard.

And (3) allowing the produced liquid at the bottom of the primary reaction tower to enter a delayer for continuous layering, wherein the upper layer is a chloromethyl ether product, the lower layer is dilute hydrochloric acid, the upper layer of chloromethyl ether is rectified and purified to obtain a finished product for sale, the lower layer of dilute hydrochloric acid enters a hydrogen chloride distillation kettle for recovering hydrogen chloride and then enters a neutralization kettle, and the neutralized product is discharged into sewage treatment.

The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner; those skilled in the art can make numerous possible variations and modifications to the present teachings, or modify equivalent embodiments to equivalent variations, without departing from the scope of the present teachings, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention.