CN113636911A - Method and device for recovering dichloromethane serving as solvent for producing acesulfame - Google Patents
Method and device for recovering dichloromethane serving as solvent for producing acesulfame Download PDFInfo
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- CN113636911A CN113636911A CN202110788592.8A CN202110788592A CN113636911A CN 113636911 A CN113636911 A CN 113636911A CN 202110788592 A CN202110788592 A CN 202110788592A CN 113636911 A CN113636911 A CN 113636911A
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- dichloromethane
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- sulfuric acid
- concentrated sulfuric
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- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 title claims abstract description 435
- 238000000034 method Methods 0.000 title claims abstract description 27
- 239000002904 solvent Substances 0.000 title claims abstract description 12
- 229960005164 acesulfame Drugs 0.000 title abstract description 7
- YGCFIWIQZPHFLU-UHFFFAOYSA-N acesulfame Chemical compound CC1=CC(=O)NS(=O)(=O)O1 YGCFIWIQZPHFLU-UHFFFAOYSA-N 0.000 title abstract description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 67
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 50
- 238000007670 refining Methods 0.000 claims abstract description 40
- 230000018044 dehydration Effects 0.000 claims abstract description 31
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 31
- 238000011084 recovery Methods 0.000 claims abstract description 7
- 238000005406 washing Methods 0.000 claims description 25
- 238000010992 reflux Methods 0.000 claims description 16
- WBZFUFAFFUEMEI-UHFFFAOYSA-M Acesulfame k Chemical compound [K+].CC1=CC(=O)[N-]S(=O)(=O)O1 WBZFUFAFFUEMEI-UHFFFAOYSA-M 0.000 claims description 10
- 239000002699 waste material Substances 0.000 claims description 10
- 239000002253 acid Substances 0.000 claims description 9
- 229960004998 acesulfame potassium Drugs 0.000 claims description 8
- 235000010358 acesulfame potassium Nutrition 0.000 claims description 8
- 239000000619 acesulfame-K Substances 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 238000004891 communication Methods 0.000 claims description 3
- 239000012530 fluid Substances 0.000 claims description 3
- 238000004821 distillation Methods 0.000 abstract description 6
- 238000005265 energy consumption Methods 0.000 abstract description 4
- 239000012535 impurity Substances 0.000 abstract description 3
- 238000004064 recycling Methods 0.000 abstract description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 16
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 description 9
- 239000010410 layer Substances 0.000 description 6
- 230000010933 acylation Effects 0.000 description 5
- 238000005917 acylation reaction Methods 0.000 description 5
- 238000006460 hydrolysis reaction Methods 0.000 description 5
- 238000007363 ring formation reaction Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 239000012044 organic layer Substances 0.000 description 3
- 238000005086 pumping Methods 0.000 description 3
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 235000003599 food sweetener Nutrition 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000003765 sweetening agent Substances 0.000 description 2
- NVKQKAZYUPPRJX-UHFFFAOYSA-N 1,3,5-tribromo-2-(2,5-dibromophenyl)benzene Chemical group BrC1=CC=C(Br)C(C=2C(=CC(Br)=CC=2Br)Br)=C1 NVKQKAZYUPPRJX-UHFFFAOYSA-N 0.000 description 1
- 206010013911 Dysgeusia Diseases 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- XXQBEVHPUKOQEO-UHFFFAOYSA-N potassium peroxide Inorganic materials [K+].[K+].[O-][O-] XXQBEVHPUKOQEO-UHFFFAOYSA-N 0.000 description 1
- 235000019605 sweet taste sensations Nutrition 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/38—Separation; Purification; Stabilisation; Use of additives
- C07C17/383—Separation; Purification; Stabilisation; Use of additives by distillation
- C07C17/386—Separation; Purification; Stabilisation; Use of additives by distillation with auxiliary compounds
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a method and a device for recovering dichloromethane serving as a solvent for producing acesulfame, which adopt a scheme of combining distillation dehydration and concentrated sulfuric acid refining. In the dehydration tower, water is separated at the top of the tower, and dichloromethane steam with qualified tower kettle water enters a refining tower; and then removing a small amount of water and impurities in the dichloromethane by concentrated sulfuric acid, condensing the top of the tower to obtain dichloromethane with qualified quality, and recycling the dichloromethane after recovery. The invention has simple process, low energy consumption and reduced cost, and conforms to the national industrial policy.
Description
Technical Field
The invention relates to the field of chemical industry, in particular to a method and a device for recovering dichloromethane serving as a solvent for producing acesulfame.
Background
Acesulfame is the common name of AK sugar (Acesulfame-K), the Chinese cultural name is 6-methyl-1, 2,3-oxathiazin-4(3H) -ketone-2, 2-potassium dioxide, and the English chemical name is 6-Methyl-1,2,3-oxathiazin-4(3H) -one 2,2-dioxide potassium salt. Appearance properties: colorless crystals. Solubility: is easily dissolved in water, and the solubility is 270g/L at 20 ℃. CAS number: 55589-62-3. The molecular formula is as follows: c4H4O4KNS. Molecular weight: 201.24. melting Point (. degree. C.): 229-232. Relative density (water ═ 1): 1.81. pH value: the pH value is 5.5-7.5. Acesulfame potassium has the advantages of safety, no toxicity, stable property, sweet taste, no bad aftertaste, proper price and the like, is one of the sweeteners with the best stability in the world at present, and is used as a sweetener in the aspects of food, medicine and the like.
The recovery of dichloromethane is an important section in the acesulfame potassium synthesis process. In the traditional dichloromethane recovery process in the acesulfame potassium production process, water-washed dichloromethane generally enters a first distillation tower for rough distillation, then enters a second distillation tower for dehydration, and finally enters a rectifying tower for refining and high boiling removal to obtain a finished dichloromethane product. The process for recycling the dichloromethane has long time, low productivity and high energy consumption, which leads to high production cost; the process is complex, the quality of the recycled dichloromethane is unstable, and the reaction is influenced.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, the present invention aims to provide a method and an apparatus for recovering dichloromethane, a solvent for producing acesulfame, which solve the problems of the prior art.
In order to achieve the above objects and other related objects, the present invention adopts the following technical solutions:
in a first aspect of the present invention, there is provided a solvent recovery method for producing acesulfame potassium, comprising the steps of:
(1) dehydrating the water-washed dichloromethane to obtain dichloromethane steam and removed water;
(2) and (2) treating the dichloromethane steam obtained in the step (1) with concentrated sulfuric acid to obtain dichloromethane and waste acid.
In one embodiment, the washing of dichloromethane with water is that a dichloromethane layer after acylation, cyclization and hydrolysis reaction is neutralized and layered with a potassium hydroxide solution, the dichloromethane layer is washed with water, and an organic layer after washing with water is washed with water, namely, washing with dichloromethane. The washing dichloromethane contains AK, water, acetone, triethylamine and other components.
In one embodiment, the water-washed dichloromethane is passed to a dehydration column for dehydration. Washing dichloromethane, continuously feeding from the middle upper part of the dehydration tower, and controlling the reflux ratio of the tower top to be 1: 5 to 10. Optionally, controlling the overhead reflux ratio of 1: 5 to 8. Optionally, controlling the overhead reflux ratio of 1: 8 to 10.
In one embodiment, in step (1), the methylene chloride vapor obtained has a water content of <200 ppm.
In one embodiment, in step (2), methylene chloride vapor is fed to a refining column for treatment.
In one embodiment, in step (2), the concentrated sulfuric acid has a concentration of 95% or more. The unit is mass percentage concentration.
In one embodiment, in step (2), the concentrated sulfuric acid has a temperature of 50 to 60 ℃.
In one embodiment, in step (2), methylene chloride vapor is countercurrently contacted with concentrated sulfuric acid.
In a second aspect of the present invention, there is provided an apparatus for recovering dichloromethane, a solvent used in the production of acesulfame potassium, comprising:
the dehydrating tower is used for dehydrating the washed dichloromethane to obtain dichloromethane steam and removed water;
the refining tower is used for treating the dichloromethane steam with concentrated sulfuric acid to obtain dichloromethane and waste acid;
the dehydration column and the finishing column are in fluid communication.
In one embodiment, the washing of dichloromethane with water is that a dichloromethane layer after acylation, cyclization and hydrolysis reaction is neutralized and layered with a potassium hydroxide solution, the dichloromethane layer is washed with water, and an organic layer after washing with water is washed with water, namely, washing with dichloromethane. The washing dichloromethane contains AK, water, acetone, triethylamine and other components.
In one embodiment, the water-washed methylene chloride is continuously fed from the middle upper part of the dehydration column, and the reflux ratio of the top of the column is controlled to be 1: 5 to 10. Optionally, controlling the overhead reflux ratio of 1: 5 to 8. Optionally, controlling the overhead reflux ratio of 1: 8 to 10.
In one embodiment, in the dehydration column, water is separated at the top of the column. The dichloromethane steam with qualified water in the tower bottom enters a refining tower. Moisture qualified methylene chloride vapor means methylene chloride vapor moisture content <200 ppm.
In one embodiment, the concentrated sulfuric acid is recycled in a refining column. The methylene chloride vapor is contacted with concentrated sulfuric acid in countercurrent.
In one embodiment, the concentrated sulfuric acid has a concentration of 95% or more. The unit is mass percentage concentration. The temperature of the concentrated sulfuric acid is 50-60 ℃.
The method and the device for recovering the dichloromethane serving as the solvent for producing the acesulfame disclosed by the invention have the following beneficial effects:
the invention adopts a scheme of combining distillation dehydration and concentrated sulfuric acid refining. In the dehydration tower, water is separated at the top of the tower, and dichloromethane steam with qualified tower kettle water enters a refining tower; then, according to the effect of the concentrated sulfuric acid on removing water and strong oxidizing property, the concentrated sulfuric acid is adopted to remove a small amount of water and impurities in the dichloromethane, and the recycled dichloromethane with qualified quality is obtained by condensing at the tower top (can be recycled, for example, used in the sections of acylation and cyclization hydrolysis). Simple process, low energy consumption, low cost and accordance with the national industrial policy.
Drawings
FIG. 1: the invention provides a schematic diagram of a device for recovering solvent dichloromethane for producing acesulfame potassium.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be understood that the processing equipment or apparatus not specifically identified in the following examples is conventional in the art. Furthermore, it is to be understood that one or more method steps mentioned in the present invention does not exclude that other method steps may also be present before or after the combined steps or that other method steps may also be inserted between these explicitly mentioned steps, unless otherwise indicated; it is also to be understood that a combined connection between one or more devices/apparatus as referred to in the present application does not exclude that further devices/apparatus may be present before or after the combined device/apparatus or that further devices/apparatus may be interposed between two devices/apparatus explicitly referred to, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the various method steps is merely a convenient tool for identifying the various method steps, and is not intended to limit the order in which the method steps are arranged or the scope of the invention in which the invention may be practiced, and changes or modifications in the relative relationship may be made without substantially changing the technical content.
A solvent methylene chloride recovery device for producing acesulfame potassium, as shown in figure 1, comprising:
the dehydrating tower 1 is used for dehydrating the washed dichloromethane to obtain dichloromethane steam and removed water;
the refining tower 2 is used for treating the dichloromethane steam with concentrated sulfuric acid to obtain dichloromethane and waste acid;
the dehydration column 1 and the refining column 2 are in fluid communication.
In one embodiment, the washing of dichloromethane with water is that a dichloromethane layer after acylation, cyclization and hydrolysis reaction is neutralized and layered with a potassium hydroxide solution, the dichloromethane layer is washed with water, and an organic layer after washing with water is washed with water, namely, washing with dichloromethane. The washing dichloromethane contains AK, water, acetone, triethylamine and other components.
In one embodiment, water-washed methylene chloride is continuously fed from the upper middle part of the dehydration column 1, and the overhead reflux ratio is controlled to 1: 5 to 10. Optionally, controlling the overhead reflux ratio of 1: 5 to 8. Optionally, controlling the overhead reflux ratio of 1: 8 to 10.
In one embodiment, in the dehydration column 1, water is separated at the top of the column. The dichloromethane steam with qualified water in the tower bottom enters a refining tower. Moisture qualified methylene chloride vapor means methylene chloride vapor moisture content <200 ppm.
In one embodiment, the concentrated sulfuric acid is recycled in the refining column 2. The methylene chloride vapor is contacted with concentrated sulfuric acid in countercurrent.
In one embodiment, the concentrated sulfuric acid has a concentration of 95% or more. The unit is mass percentage concentration. The temperature of the concentrated sulfuric acid is 50-60 ℃.
Example 1
Washing dichloromethane with water, and allowing the dichloromethane to enter a dehydration tower to obtain removed water and dichloromethane steam; and (3) allowing dichloromethane steam to enter a refining tower, and treating with concentrated sulfuric acid to obtain dichloromethane and waste acid. Specifically, washing dichloromethane (dichloromethane from a washing section, water content of 0.2%, mass percent) is continuously fed from the middle upper part of the dehydration tower, and the reflux ratio of the tower top is controlled to be 1: 5, separating and removing water at the tower top, and obtaining dichloromethane steam with the water content of 150ppm at the tower bottom; feeding dichloromethane steam from the middle part of the refining tower, adopting sulfuric acid circulation with the content of 96% (mass percent) and the temperature of 55 ℃ in the refining tower, carrying out countercurrent contact on concentrated sulfuric acid and dichloromethane steam with qualified moisture in the refining tower, condensing the tower top to obtain a finished dichloromethane product, obtaining the finished dichloromethane product if the obtained dichloromethane moisture meets the requirement (namely within the range of less than 50 ppm), and pumping the dichloromethane product back to the refining tower if the obtained dichloromethane moisture does not meet the requirement until the moisture is qualified. In the finished product dichloromethane obtained in the embodiment, the dichloromethane content is 99.96%, the water content is 40ppm, and the acetone content is 40ppm, so that the requirements of superior products are met. Waste acid is obtained from the tower bottom and can enter a waste acid treatment working section.
Example 2
Washing dichloromethane with water, and allowing the dichloromethane to enter a dehydration tower to obtain removed water and dichloromethane steam; and (3) allowing dichloromethane steam to enter a refining tower, and treating with concentrated sulfuric acid to obtain dichloromethane and waste acid. Specifically, washing dichloromethane (dichloromethane from a washing section, water content of 0.2%, mass percent) is continuously fed from the middle upper part of the dehydration tower, and the reflux ratio of the tower top is controlled to be 1: 10, separating and removing water at the top of the tower, and obtaining dichloromethane vapor with the water content of 120ppm at the bottom of the tower; feeding dichloromethane steam from the middle part of the refining tower, adopting sulfuric acid circulation with the content of 95% (mass percentage) and the temperature of 50 ℃ in the refining tower, carrying out countercurrent contact on concentrated sulfuric acid and the dichloromethane steam with qualified moisture in the refining tower, condensing the tower top to obtain dichloromethane, obtaining finished dichloromethane if the obtained dichloromethane moisture meets the requirement (namely within the range of less than 50 ppm), and pumping the dichloromethane back to the refining tower if the obtained dichloromethane moisture does not meet the requirement until the moisture is qualified. In the finished product dichloromethane obtained in the embodiment, the dichloromethane content is 99.97%, the water content is 42ppm, and the acetone content is 44ppm, so that the requirements of superior products are met.
Example 3
Washing dichloromethane with water, and allowing the dichloromethane to enter a dehydration tower to obtain removed water and dichloromethane steam; and (3) allowing dichloromethane steam to enter a refining tower, and treating with concentrated sulfuric acid to obtain dichloromethane and waste acid. Specifically, washing dichloromethane (dichloromethane from a washing section, water content 0.2%) is continuously fed from the middle upper part of the dehydration tower, and the reflux ratio of the tower top is controlled to be 1: 8, separating and removing water at the tower top, and obtaining dichloromethane steam with water content of 130ppm at the tower bottom; feeding dichloromethane steam from the middle part of the refining tower, adopting sulfuric acid circulation with the content of 95.8 percent and the temperature of 60 ℃ in the refining tower, carrying out countercurrent contact on concentrated sulfuric acid and the dichloromethane steam with qualified moisture in the refining tower, condensing the tower top to obtain a finished dichloromethane product, obtaining the finished dichloromethane product if the obtained dichloromethane moisture meets the requirement (namely within the range of less than 50 ppm), and pumping the dichloromethane product back to the refining tower if the obtained dichloromethane moisture does not meet the requirement until the moisture is qualified. In the finished product dichloromethane obtained in the embodiment, the dichloromethane content is 99.96%, the water content is 38ppm, and the acetone content is 41ppm, which meets the requirements of superior products.
Comparative example 1
Methylene chloride (water content 0.2%) from the water washing section was continuously fed from the middle-upper part of the dehydration column, and the overhead reflux ratio was controlled to be 1: 8, separating and removing water at the tower top, and obtaining dichloromethane with water content of 130ppm at the tower bottom; methylene dichloride steam is fed from the middle part of the refining tower, sulfuric acid with the content of 92% and the temperature of 45 ℃ is adopted for circulation in the refining tower, concentrated sulfuric acid and methylene dichloride steam with qualified moisture are in countercurrent contact in the refining tower, and the finished product methylene dichloride is obtained through condensation at the tower top, wherein the methylene dichloride content is 99.95%, the moisture is 90ppm, and the acetone content is 68ppm, and does not meet the requirements of superior products.
Comparative example 2
Methylene chloride (water content 0.2%) from the water washing section was continuously fed from the middle-upper part of the dehydration column, and the overhead reflux ratio was controlled to be 1: 8, separating and removing water at the tower top, and obtaining dichloromethane with water content of 130ppm at the tower bottom; methylene dichloride steam is fed from the middle part of the refining tower, sulfuric acid with the content of 90 percent and the temperature of 75 ℃ is adopted for circulation in the refining tower, concentrated sulfuric acid and methylene dichloride steam with qualified moisture are in countercurrent contact in the refining tower, and the finished product methylene dichloride with the methylene dichloride content of 99.94 percent, the moisture of 105ppm and the acetone of 85ppm is obtained by condensation at the top of the tower and does not meet the requirements of superior products.
The embodiment 1-3 of the invention adopts a scheme of combining distillation dehydration and concentrated sulfuric acid refining. In the dehydration tower, water is separated at the top of the tower, and dichloromethane steam with qualified tower kettle water enters a refining tower; then, according to the effect of water removal and strong oxidizing property of the concentrated sulfuric acid, the concentrated sulfuric acid is adopted to remove a small amount of water and impurities in the dichloromethane, and the recycled dichloromethane with qualified quality is obtained by condensing at the tower top (can be used for acylation and cyclization hydrolysis working sections). The process is simple, the energy consumption is low (only 35% of the traditional process), the cost is reduced (the cost is only 50% of the traditional process), and the method conforms to the national industrial policy. In contrast, in comparative examples 1 to 2, the dehydration and oxidation effects were much lower than in examples 1 to 3 due to the lower concentrated sulfuric acid content.
In conclusion, the present invention effectively overcomes various disadvantages of the prior art and has high industrial utilization value.
The above examples are intended to illustrate the disclosed embodiments of the invention and are not to be construed as limiting the invention. In addition, various modifications of the methods and compositions set forth herein, as well as variations of the methods and compositions of the present invention, will be apparent to those skilled in the art without departing from the scope and spirit of the invention. While the invention has been specifically described in connection with various specific preferred embodiments thereof, it should be understood that the invention should not be unduly limited to such specific embodiments. Indeed, various modifications of the above-described embodiments which are obvious to those skilled in the art to which the invention pertains are intended to be covered by the scope of the present invention.
Claims (10)
1. A solvent recovery method for producing acesulfame potassium comprises the following steps:
(1) dehydrating the water-washed dichloromethane to obtain dichloromethane steam and removed water;
(2) and (2) treating the dichloromethane steam obtained in the step (1) with concentrated sulfuric acid to obtain dichloromethane and waste acid.
2. The method according to claim 1, wherein in the step (1), the water-washed dichloromethane enters the dehydration tower for dehydration, the water-washed dichloromethane is continuously fed from the middle upper part of the dehydration tower, and the reflux ratio of the top of the tower is 1: 5 to 10.
3. The process according to claim 1, wherein in step (1), the methylene chloride vapor obtained has a water content of <200 ppm.
4. The method of claim 1, wherein in step (2), the dichloromethane vapor enters the refining tower for treatment, and the dichloromethane vapor is in countercurrent contact with concentrated sulfuric acid.
5. The method of claim 1, further comprising any one or more of the following features: (1) in the step (2), the concentration of concentrated sulfuric acid is more than or equal to 95 percent; (2) in the step (2), the temperature of the concentrated sulfuric acid is 50-60 ℃.
6. A solvent recovery apparatus for producing acesulfame k, comprising:
the dehydrating tower is used for dehydrating the washed dichloromethane to obtain dichloromethane steam and removed water;
the refining tower is used for treating the dichloromethane steam with concentrated sulfuric acid to obtain dichloromethane and waste acid;
the dehydration column and the finishing column are in fluid communication.
7. The apparatus according to claim 6, wherein the washing dichloromethane is continuously fed from the middle upper part of the dehydration column, and the overhead reflux ratio is controlled to 1: 5 to 10.
8. The apparatus of claim 6, wherein in the dehydration column, water is separated at the top of the column, and methylene dichloride steam with qualified tower bottom water enters the refining column; moisture qualified methylene chloride vapor means methylene chloride vapor moisture content <200 ppm.
9. The apparatus of claim 6, wherein concentrated sulfuric acid is circulated in the refining column and methylene chloride vapor is countercurrently contacted with the concentrated sulfuric acid.
10. The apparatus of claim 6, further comprising any one or more of the following features: (1) the concentration of the concentrated sulfuric acid is more than or equal to 95 percent; (2) the temperature of the concentrated sulfuric acid is 50-60 ℃.
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| CN202110788592.8A CN113636911A (en) | 2021-07-13 | 2021-07-13 | Method and device for recovering dichloromethane serving as solvent for producing acesulfame |
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| CN114163297A (en) * | 2021-11-26 | 2022-03-11 | 安徽金禾实业股份有限公司 | Method for recovering solvent dichloromethane in acesulfame potassium production |
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- 2021-07-13 CN CN202110788592.8A patent/CN113636911A/en active Pending
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