CN114956961A - Separation method of methanol acetone azeotrope - Google Patents
Separation method of methanol acetone azeotrope Download PDFInfo
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- CN114956961A CN114956961A CN202210425708.6A CN202210425708A CN114956961A CN 114956961 A CN114956961 A CN 114956961A CN 202210425708 A CN202210425708 A CN 202210425708A CN 114956961 A CN114956961 A CN 114956961A
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- azeotrope
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- NIQQIJXGUZVEBB-UHFFFAOYSA-N methanol;propan-2-one Chemical compound OC.CC(C)=O NIQQIJXGUZVEBB-UHFFFAOYSA-N 0.000 title claims abstract description 52
- 238000000926 separation method Methods 0.000 title abstract description 17
- 238000010992 reflux Methods 0.000 claims abstract description 31
- 238000000034 method Methods 0.000 claims abstract description 21
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 123
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 84
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 39
- 238000001816 cooling Methods 0.000 claims description 9
- 238000004821 distillation Methods 0.000 claims description 9
- 239000005457 ice water Substances 0.000 claims description 9
- 239000000126 substance Substances 0.000 claims description 3
- 239000003570 air Substances 0.000 claims description 2
- 238000005265 energy consumption Methods 0.000 abstract description 10
- 239000007788 liquid Substances 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 10
- 230000001174 ascending effect Effects 0.000 description 5
- 239000003795 chemical substances by application Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000000605 extraction Methods 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 2
- BAVYZALUXZFZLV-UHFFFAOYSA-N Methylamine Chemical compound NC BAVYZALUXZFZLV-UHFFFAOYSA-N 0.000 description 2
- NEHMKBQYUWJMIP-UHFFFAOYSA-N chloromethane Chemical compound ClC NEHMKBQYUWJMIP-UHFFFAOYSA-N 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 230000006837 decompression Effects 0.000 description 2
- SWXVUIWOUIDPGS-UHFFFAOYSA-N diacetone alcohol Chemical compound CC(=O)CC(C)(C)O SWXVUIWOUIDPGS-UHFFFAOYSA-N 0.000 description 2
- 239000003814 drug Substances 0.000 description 2
- 229940079593 drug Drugs 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- OKJPEAGHQZHRQV-UHFFFAOYSA-N iodoform Chemical compound IC(I)I OKJPEAGHQZHRQV-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 239000000575 pesticide Substances 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 229920002160 Celluloid Polymers 0.000 description 1
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 1
- 238000010533 azeotropic distillation Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000012459 cleaning agent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- VAYGXNSJCAHWJZ-UHFFFAOYSA-N dimethyl sulfate Chemical compound COS(=O)(=O)OC VAYGXNSJCAHWJZ-UHFFFAOYSA-N 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 1
- 238000000895 extractive distillation Methods 0.000 description 1
- 239000003925 fat Substances 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 229920001195 polyisoprene Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000005292 vacuum distillation Methods 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/42—Regulation; Control
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
- C07C45/81—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C45/82—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
Abstract
The invention discloses a separation method of a methanol-acetone azeotrope. Introducing the methanol acetone azeotrope into a rectifying device; wherein, the rectifying device comprises a rectifying tower, a condenser and a reboiler which are respectively connected with the top of the rectifying tower and the tower kettle; the condenser is provided with a vacuum gas phase outlet and a light component outlet; the reboiler is provided with a heavy component outlet; the pressure of the rectifying device is 0.13bar or less; the tower top temperature of the rectifying device is 6.5 ℃ or below; the temperature of the tower kettle of the rectifying device is 22.2 ℃ or below; the operation reflux ratio of the tower top of the rectification device is 6-10. The method for separating the methanol acetone azeotrope uses a single rectifying tower system, so that the total investment is low, the operation is simple, and the energy consumption is low while a high-purity product is obtained.
Description
Technical Field
The invention relates to a separation method of a methanol-acetone azeotrope.
Background
Methanol and acetone are both extremely important chemical raw materials. The methanol has wide application, is a basic organic chemical raw material and a high-quality fuel, is mainly used in the fields of fine chemical engineering, plastics and the like, can be used for manufacturing organic products such as formaldehyde, acetic acid, chloromethane, methylamine, dimethyl sulfate and the like, and is also one of important raw materials of pesticides and medicines. The methanol can be used as a novel clean fuel after deep processing, and can also be mixed with gasoline for use.
Acetone is an important organic synthetic raw material and is used for producing epoxy resin, polycarbonate, organic glass, medicines, pesticides and the like; can also be used as a good solvent for paint, adhesive, steel cylinder acetylene, etc.; can also be used as a diluent, a cleaning agent and an extracting agent; is an important raw material for preparing acetic anhydride, diacetone alcohol, chloroform, iodoform, epoxy resin, polyisoprene rubber, methyl methacrylate and the like. For example, acetone is used as a solvent in the smokeless powder, celluloid, acetate, spray paint, and like industries; is used as an extractant in the industries of fats and oils.
The boiling point of methanol is 64.53 ℃, the boiling point of acetone is 56.14 ℃, the two can form the lowest azeotrope, the azeotropic temperature is 55.5 ℃, the azeotrope comprises 22.4 percent of methanol and 77.6 percent of acetone, and the azeotrope can not be separated by the common rectification method. For the separation of azeotropes, pressure swing distillation and extractive distillation are commonly used. Separating agents are required to be introduced in the extraction and rectification, the commonly used separating agents for separating the methanol and the acetone are water and monoethanolamine, the using amount of the separating agents is large, the inevitable loss is caused, and the subsequent flow is influenced.
CN104119202A discloses an energy-saving process for separating a methanol-acetone azeotrope by pressure swing distillation, which comprises the steps of firstly reducing the pressure of the azeotrope, separating to obtain acetone, and then introducing the acetone into a pressurizing tower to increase the pressure to obtain methanol. The pressure swing distillation process does not need to add additional components, but needs at least 2 distillation columns, and has high overall cost of the device and relatively complex operation.
Disclosure of Invention
The invention mainly aims to overcome the defects of poor effect and large energy consumption of a methanol-acetone binary azeotrope system separation method in the prior art, and provides a methanol-acetone azeotrope separation method. The separation method of the methanol-acetone azeotrope uses a single rectifying tower system, and has the advantages of low total investment, simple operation and low energy consumption while obtaining a high-purity product.
The inventors of the present application found at the beginning of the study that: the existing pressure swing rectification needs two tower systems, and has more theoretical plates and higher investment cost of equipment. Moreover, the temperature of the tower kettle of the atmospheric tower is 61-62 ℃, and the temperature of the tower kettle of the pressurizing tower is 110-125 ℃. The formation of the gas phase in the tower kettle needs a proper heat source for heating, and the temperature of the tower kettle at 125 ℃ in the prior art needs at least steam of more than 3bar for heating, so that the energy consumption is large.
Through continuous exploration and experiments of the inventor and creative work, the inventor finds that the methanol-acetone separation can be realized by using a single rectifying tower, and the high-purity methanol and acetone can be obtained, so that the technical problem of the invention can be effectively solved. The technical difficulties of the invention are mainly reflected as follows: the boiling point of acetone is 56.14 ℃, the azeotropic temperature of the methanol-acetone azeotrope is 55.5 ℃, and the two are close and difficult to separate; although methanol and acetone with high purity can be separated by adopting the pressure swing operation in the prior art, the investment cost of equipment is high and the energy consumption is large. Therefore, the difficulty and key point in separating methanol and acetone is to control the process parameters in the reaction system.
The invention solves the technical problems through the following technical scheme:
the invention provides a separation method of a methanol-acetone azeotrope, which comprises the following steps of introducing the methanol-acetone azeotrope into a rectifying device; wherein the content of the first and second substances,
the rectifying device comprises a rectifying tower, a condenser and a reboiler, wherein the condenser and the reboiler are respectively connected with the top of the rectifying tower and the tower kettle; the condenser is provided with a vacuum gas phase outlet and a light component outlet; the reboiler is provided with a heavy component outlet;
the pressure of the rectifying device is 0.13bar or less;
the tower top temperature of the rectifying device is 6.5 ℃ or below;
the temperature of the tower kettle of the rectifying device is 22.2 ℃ or below;
the operation reflux ratio of the tower top of the rectification device is 6-10.
In the present invention, the rectifying apparatus may further include a pressure reducing apparatus.
The pressure reducing device is preferably arranged at the vacuum gas phase outlet and is used for controlling the pressure of the rectifying tower.
In the present invention, a light component reflux path is preferably provided between the top of the rectifying column and the condenser.
In the present invention, a heavy component reflux passage is preferably provided between the column bottom of the rectifying column and the reboiler.
In the present invention, the pressure of the rectifying apparatus is preferably 0.001 to 0.13bar, and more preferably 0.13 bar. When the pressure of the rectifying tower is higher than 0.13bar, the methanol-acetone azeotrope can not be separated; when the pressure of the rectifying tower is too low, the temperature of the whole tower needs to be reduced, and the temperature of the top of the tower needs to be reduced, so that ice water with lower temperature is needed for cooling, and the operation cost is increased.
In the invention, the tower top temperature is preferably 0-6.5 ℃, and more preferably 6.4-6.5 ℃.
In the invention, the temperature of the tower kettle is preferably 10-22.2 ℃, more preferably 22.1-22.2 ℃, if the temperature of the tower kettle exceeds the temperature of the tower kettle, a large amount of methanol is evaporated to the top of the tower, and the separation effect is poor.
In the present invention, the number of plates in the rectifying column is preferably 40 to 65, and more preferably 40 or 65. The number of trays is inversely proportional to the energy consumption within a certain range, i.e., the more trays, the lower the energy consumption, but the higher the investment cost is brought by the increase of the number of trays. In view of the correspondingly higher operating costs, a suitable increase in the number of trays makes it possible to significantly reduce the operating costs.
Wherein, when the number of the tower plates of the rectifying tower is 40, the methanol-acetone azeotrope is preferably fed in from 17 th to 27 th tower plates.
In a preferred embodiment, when the number of the plates of the rectifying tower is 40, the methanol acetone azeotrope is preferably fed from the 20 th to the 25 th plates.
Wherein, when the number of the tower plates of the rectifying tower is 65, the methanol-acetone azeotrope is preferably fed in from 35 th to 45 th tower plates.
In another preferred embodiment, when the number of the plates of the rectifying tower is 65, the methanol acetone azeotrope is preferably fed from 37 th to 40 th plates.
In the present invention, the operating reflux ratio at the top of the column is preferably 6 to 7, for example 7. The higher the reflux ratio, the higher the purity of the obtained product, but the energy consumption is increased correspondingly.
In the present invention, the methanol acetone azeotrope may include methanol, acetone and water.
Wherein the methanol, the acetone and the water can be in any proportion.
Wherein, the mass fraction of the methanol is 5-24%, the mass fraction of the acetone is 75-94%, and the mass fraction of the water is 0.01-2%.
More preferably, the mass fraction of methanol is 19.98%, the mass fraction of acetone is 80%, and the mass fraction of water is 0.02%.
In the present invention, the cooling source of the condenser is preferably ice water.
Wherein the temperature of the ice water is preferably 0 ℃; the ice water was made by a chiller as is conventional in the art.
In the present invention, the heat source of the reboiler is preferably hot water.
Wherein the temperature of the hot water is preferably 50 ℃.
In the present invention, the product at the top of the rectification apparatus may include vacuum gas phase and light component products.
Wherein the light component product may comprise acetone, methanol and water; in the light component product, the mass fraction of acetone is preferably greater than 99.5%, and the total mass fraction of methanol and water is preferably equal to or less than 0.5%.
Wherein the vacuum gas phase may comprise one or more of acetone, methanol, water, and air. During vacuum operation, air leaks into the system and is pumped to the vacuum pump as non-condensed steam.
In the invention, the product in the tower bottom of the rectifying device can comprise heavy component products.
Wherein the heavy ends product may comprise methanol, acetone, and water; in the heavy component product, the mass fraction of the methanol is more than 99.85%, and the total mass fraction of the acetone and the water is preferably less than or equal to 0.15%.
In the invention, the separation method of the methanol-acetone azeotrope has advantages no matter the early investment of the rectification device or the operation cost of the later separation method; and the operating point of a single rectifying tower is less, and the subsequent operation and maintenance are more convenient.
On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.
The reagents and starting materials used in the present invention are commercially available.
The positive progress effects of the invention are as follows:
(1) the method for separating the methanol-acetone azeotrope can separate methanol and acetone by using a single rectifying tower without azeotropic distillation of methanol and acetone under the pressure condition of less than 0.13 bar. The temperature of the tower bottom is reduced to 22.2 ℃ and below from more than 60 ℃ in the prior art, the tower bottom can not use steam, and only uses hot water as a heat source. The investment cost and the operation cost are both greatly reduced.
(2) The separation method of the methanol acetone azeotrope has the advantages that the pressure is limited to be 0.13bar, the temperature floating range of the tower top/tower bottom is reduced, and the safety is higher.
(3) The separating device of the methanol acetone azeotrope of the invention only needs one separating device (rectifying tower/reboiler/condenser). In the former investment, a separation device is saved, the investment cost is reduced by about half, and the occupied area is also reduced by about half.
Drawings
FIG. 1 shows a methanol acetone azeotrope separation apparatus according to example 1 of the present invention.
Description of reference numerals:
1-methanol acetone azeotrope inlet; 2-a rectifying tower; 3-a condenser; 4-a reboiler; 5-vacuum gas phase outlet; 6-a light component outlet; 7-heavy component outlet.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.
To better illustrate the invention and to facilitate the understanding of the technical solutions thereof, typical but non-limiting examples of the invention are as follows:
FIG. 1 shows a methanol acetone azeotrope separation apparatus according to example 1 of the present invention.
Example 1
Feeding a methanol-acetone azeotrope with the mass fraction of 19.98% of methanol, 80% of acetone and 0.02% of water at 30 ℃ into a rectifying tower 2 from a methanol-acetone azeotrope inlet 1 at the flow rate of 1000kg/h through a 20 th-25 th plate, wherein the actual number of tower plates of the rectifying tower 2 is 40, the operating pressure at the top of the tower is 0.13bar, ascending steam at the top of the tower is condensed by a condenser 3, the condenser uses chilled water as a cooling source, the operating temperature at the top of the tower is 6.5 ℃, reflux liquid flows back from the top of the tower, the operating reflux ratio is 7, acetone with the mass fraction of 99.58% flows out from a light component outlet 6, and the extracted amount is 199.8 kg/h; the tower bottom circulating liquid is heated to 22.5 ℃ by a reboiler 4 and then refluxes, methanol with the mass fraction of 99.87 percent flows out from a heavy component outlet 7, and the extraction amount is 800.2 kg/h; the vacuum gas phase outlet 5 is connected to a vacuum system so that the whole column system is at an operating pressure of 0.13 bar.
The invention only needs one rectifying device (rectifying tower/reboiler/condenser) to separate the methanol acetone azeotrope. In terms of early investment, a set of tower system is omitted, investment cost is reduced by about half, and occupied area is reduced by about half. The gas phase with the tower top temperature of 6.5 ℃ needs ice water with the temperature of about 0 ℃ as a cooling source, generally needs a set of water chilling unit for production, and has extra power consumption. The tower kettle only needs hot water of about 50 ℃, and the cost of steam is saved.
Obviously, compared with the conventional pressure swing rectification and extractive rectification device in the field, the pressure swing rectification and extractive rectification device reduces 1 tower and matched equipment in equipment investment, and saves energy consumption by at least 50%.
Example 2
Feeding a methanol-acetone azeotrope with the mass fraction of 19.98% of methanol, 80% of acetone and 0.02% of water at 30 ℃ into a rectifying tower 2 from a methanol-acetone azeotrope inlet 1 at the flow rate of 1000kg/h through 37 th-40 th plates, wherein the actual number of tower plates of the rectifying tower 2 is 65, the operating pressure at the top of the tower is 0.13bar, ascending steam at the top of the tower is condensed by a condenser 3, the condenser uses chilled water as a cooling source, the operating temperature at the top of the tower is 6.4 ℃, reflux liquid flows back from the top of the tower, the operating reflux ratio is 7, acetone with the mass fraction of 99.96% is taken from a light component outlet 6, and the extracted amount is 199.8 kg/h; the tower bottom circulating liquid is heated to 22.18 ℃ by a reboiler 4 and then refluxes, methanol with the mass fraction of 99.96% flows out from a heavy component outlet 7, and the extraction amount is 800.2 kg/h; the vacuum gas phase outlet 5 is connected to a vacuum system so that the whole column system is at an operating pressure of 0.13 bar.
Example 3
The method and the operation parameters of the embodiment 1 are adopted, and the only difference is that the reflux ratio is 6, so that the purity of acetone of a tower top product can only reach 98.69 percent, and the purity of methanol of a tower bottom product can only reach 99.64 percent. The corresponding overhead and kettle loadings at this point were 218.36kw and 211.09 kw.
Example 4
Feeding a methanol-acetone azeotrope with the mass fraction of 19.98 percent of methanol, 80 percent of acetone and 0.02 percent of water at the temperature of 30 ℃ into a rectifying tower 2 from a 27 th plate at a flow rate of 1000kg/h from a methanol-acetone azeotrope inlet 1, wherein the actual number of tower plates of the rectifying tower 2 is 50, the operating pressure at the top of the tower is 0.13bar, ascending steam at the top of the tower is condensed by a condenser 3, the condenser uses chilled water as a cooling source, the operating temperature at the top of the tower is 6.5 ℃, reflux liquid flows back from the top of the tower, the operating reflux ratio is 6.91, and acetone with the mass fraction of 99.84 percent is taken from a light component outlet 6; the tower bottom circulating liquid is heated to 22.2 ℃ by a reboiler 4 and then refluxes, and methanol with the mass fraction of 99.94 percent flows out from a heavy component outlet 7; the vacuum gas phase outlet 5 is connected to a vacuum system so that the whole column system is at an operating pressure of 0.13 bar.
Comparative example 1
The method for separating the methanol-acetone azeotrope by using double-tower pressure swing distillation comprises the following steps:
the actual plate number of the vacuum distillation tower is 50, the operation pressure is 0.85atm, the operation reflux ratio is 2.5, the tower top temperature is about 50 ℃, the tower bottom temperature is 61-62 ℃, 30 ℃ azeotropic mixture 1 with mass fraction of 19.98% methanol, 80% acetone and 0.02% water enters from the 30 th plate at the flow rate of 1000kg/h, and ascending steam at the tower top is condensed by a first condenser. Refluxing liquid flows back from the top of the decompression rectifying tower, and the produced liquid is pumped into the pressurization rectifying tower through a pressurization pump (3atm), wherein the absolute pressure of the pressurization rectifying tower is 2 atm. Refluxing liquid of the reduced pressure distillation tower after reboiling at 60-70 ℃ by a first reboiler, wherein the produced liquid at the tower bottom is methanol with the mass fraction of 99.87%, and the produced amount is 800.2 kg/h.
The actual plate number of the pressurized rectifying tower is 50, pressurized rectification is adopted, the absolute pressure is 2atm, ascending steam at the top of the pressurized rectifying tower is condensed by a second condenser, the operation reflux ratio is 2.7, and light components return to a 15 th tower plate of the reduced pressure rectifying tower after heat is supplied to an intermediate reboiler of the reduced pressure rectifying tower for circulation. Refluxing the reflux liquid from the top of the pressurized rectifying tower; tower top reflux of the pressurized rectifying tower; the tower bottom reflux liquid of the pressurized rectifying tower is reboiled at the temperature of 110-plus-120 ℃ by a second reboiler and then returns to the pressurized rectifying tower, the weight fraction of the heavy component of the pressurized rectifying tower is 99.58 percent of acetone, and the extraction amount is 199.8 kg/h.
Comparative example 2
When the operating pressure at the top of the column is 0.2bar, the single rectification column of the present application cannot separate methanol and acetone because methanol and acetone still form an azeotrope.
Comparative example 3
The method for separating the methanol-acetone azeotrope by using double-tower pressure swing distillation comprises the following steps:
the system and part of the operating parameters of comparative example 1 were used, with the difference that: (1) the operating reflux ratio of the decompression rectifying tower is 2.4; (2) the position of a feed plate of the pressurized rectifying tower is the 11 th block, and the reflux ratio of the pressurized rectifying tower is 4.2.
Effect example 1
The condensation power in example 1 was about 245kw, and the total heating power in the column in comparative example 1 was about 800 kw.
The condensation power in example 2 was 215 kw.
The overhead load of example 4 required the ice water chiller to consume electricity to produce ice water, while the kettle temperature was very low, only 22 ℃, for convenience compared to comparative example 3, using circulating water as the heat source to provide heat, resulting in overhead and kettle loads of 243.4kw and 236.1kw, respectively, for a single rectification column.
Comparative example 3 considering energy-saving operation, the top gas phase of the pressure column can be used as the heat source of the pressure reducing column, but the top of the pressure reducing column needs circulating water for cooling, and the bottom of the pressure column needs steam as the heat source, so that the loads of the top of the pressure reducing column and the bottom of the pressure column are 415kw and 477.8kw, respectively.
In terms of the number of devices to be installed,
the double column flow of comparative example 3 requires one more column and one more reboiler; embodiment 4 only requires a chiller to be provided.
From the aspect of the operating cost,
comparison of energy consumption: the two-column scheme of comparative example 3 requires steam as the heat source, the latent heat of the low pressure steam is about 2706.2kJ/kg, the heat load of 477.8kw requires about 635.6kg/h steam usage, estimated as 150 RMB/ton of low pressure steam, and the expected operating cost of the steam is 95.34 RMB/hr. Example 4 the power consumption of the chiller needs to be provided, the power consumption required for the cooling capacity of 243.4kw is about 51kw, which is estimated according to the coefficient of performance (COP) of the screw chiller in summer, and the estimated power consumption operating cost is 56.1 yuan/hour, which is calculated according to the average price of industrial electricity of 1.1 yuan/degree.
Comparison of circulating water: the tower kettle of the embodiment 4 needs circulating water to be heated to a set temperature of 22.2 ℃, and the circulating water is needed to provide 236.1kw of heat; compared with the double-tower flow of the comparative example 3, 415kw of cold energy needs to be provided, circulating water needs to be consumed, according to the heat exchange temperature difference of 10 ℃ of the circulating water, 35.74 tons/hour is needed, the cost is estimated to be 0.5 yuan/ton, and the operation cost is 17.87 yuan/hour.
The applicant states that the process of the present invention is illustrated by the above examples, but the present invention is not limited to the above procedures, i.e. it does not mean that the present invention must rely on the above procedures to be carried out. It will be apparent to those skilled in the art that any modification of the present invention, equivalent substitutions of selected materials and additions of auxiliary components, selection of specific modes and the like, which are within the scope and disclosure of the present invention, are contemplated by the present invention.
Claims (10)
1. A method for separating methanol acetone azeotrope is characterized in that the methanol acetone azeotrope is introduced into a rectifying device; wherein the content of the first and second substances,
the rectifying device comprises a rectifying tower, a condenser and a reboiler which are respectively connected with the tower top and the tower kettle of the rectifying tower; the condenser is provided with a vacuum gas phase outlet and a light component outlet; the reboiler is provided with a heavy component outlet;
the pressure of the rectifying device is 0.13bar or less;
the tower top temperature of the rectifying device is 6.5 ℃ or below;
the temperature of the tower kettle of the rectifying device is 22.2 ℃ or below;
the operation reflux ratio of the tower top of the rectification device is 6-10.
2. The method of claim 1, wherein the rectification means further comprises a pressure reduction means; the pressure reducing device is arranged at the vacuum gas phase outlet;
and/or a light component reflux passage is arranged between the top of the rectifying tower and the condenser;
and/or a heavy component reflux passage is arranged between the tower kettle of the rectifying tower and the reboiler.
3. The method for separating methanol acetone azeotrope according to claim 1, wherein the pressure of the rectification apparatus is 0.001 to 0.13 bar;
and/or the temperature at the top of the tower is 0-6.5 ℃;
and/or the temperature of the tower kettle is 10-22.2 ℃;
and/or the number of the tower plates of the rectifying tower is 40-65;
and/or the operation reflux ratio of the tower top is 6-7.
4. The method for separating methanol acetone azeotrope according to claim 3 wherein the pressure of said rectifying unit is 0.13 bar;
and/or the temperature of the tower top is 6.4-6.5 ℃;
and/or the temperature of the tower kettle is 22.1-22.2 ℃;
and/or the number of the plates of the rectifying tower is 40 or 65;
and/or the operating reflux ratio at the top of the column is 7.
5. The method for separating methanol acetone azeotrope according to claim 4, wherein when the number of the distillation tower plates is 40, the methanol acetone azeotrope is introduced from 17 th to 27 th plates, preferably from 20 th to 25 th plates.
6. The method for separating methanol acetone azeotrope according to claim 5, wherein when the number of the distillation tower trays is 65, the methanol acetone azeotrope is introduced from 35 th to 45 th trays, preferably from 37 th to 40 th trays.
7. The method of claim 1, wherein the methanol acetone azeotrope comprises methanol, acetone and water.
8. The method for separating the methanol acetone azeotrope according to claim 7, wherein in the methanol acetone azeotrope, the mass fraction of the methanol in the methanol acetone azeotrope is 5 to 24%, the mass fraction of the acetone in the methanol acetone azeotrope is 75 to 94%, and the mass fraction of the water in the methanol acetone azeotrope is 0.01 to 2%; preferably, in the methanol-acetone azeotrope, the mass fraction of methanol is 19.98%, the mass fraction of acetone is 80%, and the mass fraction of water is 0.02%.
9. The method for separating methanol acetone azeotrope according to claim 1, wherein the cooling source of the condenser is ice water; wherein the temperature of the ice water is 0 ℃;
and/or the heat source of the reboiler is hot water; wherein the temperature of the hot water is 50 ℃.
10. The method for separating methanol acetone azeotrope according to claim 1, wherein the product at the top of the rectification apparatus comprises vacuum gas phase and light component products;
wherein the light component product comprises acetone, methanol and water; in the light component product, the mass fraction of the acetone is more than 99.5 percent, and the total mass fraction of the methanol and the water is less than or equal to 0.5 percent;
wherein the vacuum gas phase comprises one or more of acetone, methanol, water, and air;
and/or the product of the tower bottom of the rectifying device comprises a heavy component product; wherein the heavy ends product comprises methanol, acetone and water; in the heavy component product, the mass fraction of the methanol is more than 99.85 percent, and the total mass fraction of the acetone and the water is less than or equal to 0.15 percent.
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| GB572897A (en) * | 1943-03-19 | 1945-10-29 | Aluminium Plant & Vessel Co | Improvements in or relating to the treatment by distillation of complex mixtures |
| WO2000044698A1 (en) * | 1999-01-28 | 2000-08-03 | Izak Nieuwoudt | Separation of methanol and acetone from mixtures thereof by extractive distillation |
| CN104119202A (en) * | 2014-07-29 | 2014-10-29 | 河北工业大学 | Energy-saving technique for separating methanol-acetone azeotrope by variable-pressure rectification |
| CN112403015A (en) * | 2020-11-03 | 2021-02-26 | 汇智工程科技股份有限公司 | Device and method for separating acetone-n-heptane mixture by extractive distillation |
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2022
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| GB572897A (en) * | 1943-03-19 | 1945-10-29 | Aluminium Plant & Vessel Co | Improvements in or relating to the treatment by distillation of complex mixtures |
| WO2000044698A1 (en) * | 1999-01-28 | 2000-08-03 | Izak Nieuwoudt | Separation of methanol and acetone from mixtures thereof by extractive distillation |
| CN104119202A (en) * | 2014-07-29 | 2014-10-29 | 河北工业大学 | Energy-saving technique for separating methanol-acetone azeotrope by variable-pressure rectification |
| CN112403015A (en) * | 2020-11-03 | 2021-02-26 | 汇智工程科技股份有限公司 | Device and method for separating acetone-n-heptane mixture by extractive distillation |
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