CN110698340A - Process method for producing ethyl lactate by reactive distillation dividing wall tower technology - Google Patents
Process method for producing ethyl lactate by reactive distillation dividing wall tower technology Download PDFInfo
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- B01D—SEPARATION
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- 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
- B01D3/143—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
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Abstract
The invention provides a process method for producing ethyl lactate by utilizing a reactive distillation bulkhead tower technology, which is characterized in that the production of ethyl lactate is completed in a reactive distillation bulkhead tower, the esterification reaction of lactic acid and ethanol is completed in a middle-section feeding side reaction section of the reactive distillation bulkhead tower to generate ethyl lactate and water, the separation of ethanol and the esterification product water is completed through a middle-section extraction side rectification section, meanwhile, the purification of ethyl lactate is realized in a middle-section feeding side stripping section and a middle-section extraction side stripping section, and finally, a food-grade ethyl lactate product is obtained at the bottom of the tower. Compared with the prior art, the process has the advantages of high yield of ethyl lactate products, high integration of equipment, short process flow, low one-time investment and operation cost and the like.
Description
Technical Field
The invention belongs to the technical field of organic solvent synthesis, relates to a method for continuously producing ethyl lactate, and particularly relates to a process method for producing ethyl lactate by a reactive distillation bulkhead tower technology.
Background
Ethyl lactate, also known as ethyl 2-hydroxypropionate, has the molecular formula C5H10O3The organic alcohol-based organic acid-base flavoring agent has the relative molecular mass of 118.13, the melting point of-26 ℃ and the boiling point of 154.5, is colorless liquid, has fragrance like nitrogen ether and white peel, is completely soluble and partially hydrolyzed with water, is easily soluble in most organic solvents, is an important used spice, is used for wine, essence additives and the like in the food industry, and can be widely applied to the industry because the organic alcohol-based organic acid-base flavoring agent has the non-toxic and biodegradable properties.
In the third part of the "synthetic perfumes" of the handbook of synthetic use, a method for synthesizing ethyl lactate is described: the lactic acid and the ethanol are catalyzed by concentrated sulfuric acid, chlorosulfonic acid or benzenesulfonic acid to synthesize the ethyl lactate. This reaction is an equilibrium reaction, and in order to obtain a high conversion rate of lactic acid, it is necessary to continuously remove water produced in the esterification reaction, and to continuously break the equilibrium of the reaction, proceeding in the forward direction. At present, the industrial synthesis of ethyl lactate generally adopts an intermittent esterification method, lactic acid and ethanol are subjected to esterification reaction under the catalytic action of concentrated sulfuric acid, then benzene, toluene and the like are used as water-carrying agents, water in a reaction system is removed to enable balance to move towards a positive direction, a crude product of ethyl lactate is obtained, and an ethyl lactate product is obtained through intermittent reduced pressure distillation. The process has the advantages of long reaction time, serious corrosion to equipment, long process flow, complex post-treatment and easy pollution, and sulfuric acid can promote the lactic acid to generate intermolecular and intramolecular dehydration reaction, condensation reaction, cyclization reaction, partial carbonization and other side reactions, so that the ethyl lactate product has poor chromaticity and low yield.
In the patent CN1032855C, absolute ethyl alcohol with the purity of 99.1-99.6% is used as a dehydrating agent, water produced by reaction is removed, the ethyl alcohol is extracted from a distillation tower in an azeotrope form of the ethyl alcohol and the water to obtain food grade ethyl lactate, and the yield of the ethyl lactate is improved to 97.2%. The method is still an intermittent process, and uses absolute ethyl alcohol as a water-carrying agent, and because the mass ratio of the ethyl alcohol to the water in the ethyl alcohol-water azeotrope is 15 to 1, a large amount of absolute ethyl alcohol is needed, and the operation cost is increased.
Patent CN100427453C uses catalytic rectification technology to synthesize ethyl lactate, lactic acid and ethanol are in catalytic reaction in the catalytic section of the catalytic rectification tower under the action of strong acid ion exchange resin catalyst to generate ethyl lactate and water, ethanol and water are condensed in the overhead condenser, then part of the overhead flows back, and part of the overhead flows back along with ethanol, and the tower bottom product passes through the flash distillation tower to remove impurities in the tower bottom product, thus obtaining the ethyl lactate product. The method uses a catalytic rectification technology, changes batch operation into continuous operation, ensures that water generated by esterification reaction is still mixed with ethyl lactate, and does not realize separation of water and ethyl lactate, thereby resulting in lower product yield.
Patent CN107032984A discloses a method for continuously synthesizing ethyl lactate, in which lactic acid and ethanol are subjected to esterification reaction in a fixed bed reactor loaded with an acidic cation exchange resin catalyst to obtain a crude product of ethyl lactate, and the crude product of ethyl lactate sequentially passes through a rough separation tower, an ethanol tower, a lactic acid tower and an ethyl lactate tower to obtain food grade ethyl lactate. The crude ethyl lactate still contains water, and the process is long, so that the yield of the ethyl lactate is low, and the primary investment and the operating cost are high.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a process method for producing ethyl lactate by a reactive distillation dividing wall tower technology, which improves the esterification reaction rate and extracts water generated by the esterification reaction in time on the premise of ensuring the yield of the ethyl lactate.
In order to achieve the purpose, the technical scheme of the invention is as follows: a process for preparing ethyl lactate by reactive rectifying bulkhead tower technique includes such steps as preparing ethyl lactate in a reactive rectifying bulkhead tower, esterifying reaction between lactic acid and alcohol in the reaction segment at the feed side of middle segment of reactive rectifying bulkhead tower to obtain ethyl lactate and water, separating alcohol from water of esterified product by the rectifying segment at the extraction side of middle segment of bulkhead tower, purifying ethyl lactate in the stripping segment at the feed side of middle segment of bulkhead tower and the extraction section at extraction side of middle segment of bulkhead tower, and obtaining food-class ethyl lactate product at bottom of tower.
The process of the invention is characterized in that: the reactive distillation dividing wall tower comprises 7 areas, namely a full-tower rectifying section, a middle-section feeding side reaction section, a middle-section feeding side stripping section, a middle-section extraction side rectifying section, a middle-section extraction side stripping section and a tower kettle; the method comprises the following steps that (1) lactic acid and ethanol are subjected to esterification reaction in a middle-section feeding-side reaction section, water generated by the esterification reaction is enriched in a middle-section feeding-side rectifying section and a full-tower rectifying section, a mixture of ethanol and water condensed at the tower top is totally refluxed to a first tower plate of the full-tower rectifying section, the ethanol and the water are separated in a middle-section extraction-side rectifying section, the water and ethyl lactate are separated in a middle-section extraction-side stripping section, and water is extracted between the middle-section extraction-side rectifying section and a middle-section extraction-side stripping section; the generated ethyl lactate is separated from ethanol in a stripping section at the feed side of the middle section, and an ethyl lactate product is obtained at the bottom of the tower.
According to the above, the reactive distillation bulkhead column system applied in the process of the invention comprises: a full-tower rectifying section, a middle-section feeding-side reaction section, a middle-section feeding-side stripping section, a middle-section extraction-side rectifying section, a middle-section extraction-side stripping section, a tower kettle, a tower top condenser and a tower kettle reboiler; fresh lactic acid is conveyed to the first tower plate of the middle feeding side reaction section by a pipeline, and fresh ethanol is conveyed to the first tower plate below the middle feeding side reaction section by the pipeline; the method comprises the steps that lactic acid and ethanol are subjected to esterification reaction in a liquid layer on a tower plate of a middle-section feeding-side reaction section, generated water is enriched in a middle-section feeding-side rectifying section and a full-tower rectifying section, tower top water and ethanol gas enter a tower top condenser, the tower top condenser is condensed to a bubble point and then totally flows back to a first tower plate of the full-tower rectifying section to serve as tower top backflow, a liquid-phase mixture of the ethanol and the water enters a middle-section extraction-side rectifying section, the separation of the ethanol and the water is completed, and water is extracted from a water outlet pipeline between the middle-section extraction-side rectifying section and a middle-section extraction-side stripping section; separating ethyl lactate and ethanol in a middle-section feeding side stripping section, wherein the ethyl lactate and the ethanol generated in the esterification reaction are separated in a middle-section extracting side stripping section, and the middle-section extracting side stripping section is used for separating ethyl lactate and water and preventing water from entering a tower kettle ethyl lactate product; the tower bottom is ethyl lactate, part of the ethyl lactate enters a reboiler of the tower bottom, is heated by steam and then returns to the tower bottom in a vapor phase form to be used as a vapor phase of the tower bottom, and part of the ethyl lactate is taken as a product and is extracted from the tower bottom.
The invention is characterized in that esterification reaction, separation of water and ethanol and separation of ethyl lactate and ethanol water are simultaneously completed by a reaction rectification dividing wall tower, and food-grade ethyl lactate is obtained in a tower kettle, namely functions of five devices of an esterification reaction kettle, a neutralization kettle, a water washing kettle, a reduced pressure distillation tower and an ethanol recovery tower in the prior art are completed by one reaction rectification dividing wall tower, so that the process is more compact and integrated.
High boiling point reactant lactic acid is fed from the upper part of the middle feeding side reaction section, and low boiling point reactant ethanol is fed from the lower part of the middle feeding side reaction section, so that the ethanol in the liquid phase on the lower tower plate of the middle feeding side reaction section is maintained at a high concentration, and the lactic acid in the liquid phase on the upper tower plate of the middle feeding side reaction section is maintained at a high concentration, so that the two reactants on the whole middle feeding side reaction section tower plate are maintained at a relatively high concentration, and the ethyl lactate and the water generated by the esterification reaction are rapidly separated, the ethyl lactate is enriched downwards, the water is enriched upwards, so that the reaction balance is moved rightwards, and the conversion rate of the lactic acid is improved.
The water generated by the esterification reaction of the middle feeding side reaction section is enriched in the middle feeding side rectifying section and the whole tower rectifying section, the concentration of the water reaches the maximum value when the concentration of the water at the top of the tower reaches the maximum value, the water and the ethanol gas enter a tower top condenser, the water and the ethanol gas are condensed to a bubble point in the tower top condenser and then flow back to the first tower plate of the whole tower rectifying section to serve as tower top backflow, one part of the liquid of the lowest tower plate of the whole tower rectifying section enters the first tower plate of the middle feeding side rectifying section, and the other part of the liquid enters the first tower plate of the middle extraction side rectifying section; because the vapor phase of the middle-section extraction side rectifying section and the middle-section extraction side stripping section does not contain ethanol, water is continuously enriched from top to bottom in the middle-section extraction side rectifying section, the lowest part of the middle-section extraction side rectifying section reaches the maximum value of a water concentration full tower, and water is extracted from the system through a water outlet pipeline between the middle-section extraction side rectifying section and the middle-section extraction side stripping section, so that the rapid separation of ethyl lactate and water is ensured.
The reactive distillation dividing wall tower used in the invention is divided into a full-tower rectifying section, a middle-section feeding side reaction section, a middle-section feeding side stripping section, a middle-section extraction side rectifying section, a middle-section extraction side stripping section and a tower kettle seventh part; the middle lower part of the tower is provided with a clapboard which divides the middle section into a middle section feeding side and a middle section extraction side, the middle section feeding side comprises a middle section feeding side rectifying section, a middle section feeding side reaction section and a middle section feeding side stripping section from top to bottom in sequence, and the middle section extraction side comprises a middle section extraction side rectifying section and a middle section extraction side stripping section from top to bottom in sequence.
The number of the reaction rectifying bulkhead tower trays used in the invention is 25-90, wherein the number of the full tower rectifying section trays is 2-10, the number of the middle feeding side rectifying section trays is 5-20, the number of the middle feeding side reaction section trays is 15-50, the number of the middle feeding side stripping section trays is 3-10, the number of the middle extraction side rectifying section trays is 13-50, and the number of the middle extraction side stripping section trays is 10-30.
According to the invention, the operating pressure of the reactive distillation bulkhead tower is 20-101 kPaA, the temperature of the reaction section at the feed side of the middle section of the reactive distillation bulkhead tower is 70-120 ℃, the temperature of the top of the reactive distillation bulkhead tower is 40-85 ℃, and the temperature of the bottom of the reactive distillation bulkhead tower is 110-160 ℃;
according to the invention, the molar ratio of fresh ethanol to fresh lactic acid is 1.05-1.3: 1
The reaction rectifying bulkhead tower is a plate tower or a packed tower, the plate tower is a float valve, a bubble cap or a sieve plate, and the packing is regular packing or random packing;
in the invention, the tower plates or the fillers of the reaction rectifying bulkhead tower are made of metal, ceramic, polytetrafluoroethylene, plastic and the like;
according to the invention, the solid catalyst loaded on the reaction section at the feed side of the middle section of the reactive distillation bulkhead tower is macroporous sulfonic acid resin or a super-strong solid acid catalyst.
In order to reduce the energy consumption of the process as much as possible, the invention also comprises a steam compression type heat pump rectification technology, a compressor is used for compressing the vapor phase at the top of the tower, the vapor phase is heated and pressurized and then exchanges heat with a reboiler at the bottom of the tower to provide heat, at the moment, the system needs to additionally increase one compressor, and a condenser at the top of the tower is eliminated;
the invention has the beneficial effects that:
1. the reaction rectification quickly removes ethyl lactate and water produced by the esterification reaction, reduces the concentration of two products in the reaction liquid, enables the esterification reaction balance to continuously move rightwards, and greatly improves the conversion rate of the raw material lactic acid;
2. the reaction rectifying bulkhead tower integrates the esterification reaction and the product separation into one device to be completed, thereby greatly simplifying the separation process of a subsequent system;
3. because the reaction distillation dividing wall tower has the separation function, the lactic acid and the ethanol with higher water content can still be used as the raw materials of the invention.
4. Compared with the prior art, the one-time investment and the operation cost can be respectively reduced to about 30 percent and 40 percent of the original cost, and the operation cost can be further reduced by about 20 percent by adopting the vapor compression type heat pump rectification technology.
Drawings
FIG. 1 is a sectional view of a reactive distillation dividing wall column;
wherein: a-a reactive distillation dividing wall column; b-a full-tower rectifying section; c, a middle section feed side rectifying section; d, a middle section feed side reaction section; e, a middle section feed side stripping section; f, a middle section extraction side rectifying section; g, extracting a side stripping section from the middle section; h-tower kettle; i-a separator.
FIG. 2-Process flow diagram;
wherein: a-a reactive distillation dividing wall column; b-a full-tower rectifying section; c, a middle section feed side rectifying section; d, a middle section feed side reaction section; e, a middle section feed side stripping section; f, a middle section extraction side rectifying section; g, extracting a side stripping section from the middle section; h-tower kettle; i-a separator; j-overhead condenser; k-column kettle reboiler; 1-fresh lactic acid line; 2-fresh ethanol line; 3-produced water pipeline; 4-ethyl lactate product line; 5-overhead vapor phase line; 6-overhead reflux line; 7-reboiler liquid phase line; 8-reboiler vapor phase line.
FIG. 3-Heat Pump rectification Process flow diagram;
wherein: a-a reactive distillation dividing wall column; b-a full-tower rectifying section; c, a middle section feed side rectifying section; d, a middle section feed side reaction section; e, a middle section feed side stripping section; f, a middle section extraction side rectifying section; g, extracting a side stripping section from the middle section; h-tower kettle; i-a separator; k-column kettle reboiler; an L-compressor; 1-fresh lactic acid line; 2-fresh ethanol line; 3-produced water pipeline; 4-ethyl lactate product line; 5-overhead vapor phase line; 6-overhead reflux line; 7-reboiler liquid phase line; 8-reboiler vapor phase line; 9-compressor outlet line.
Detailed Description
The following detailed description is made with reference to the accompanying drawings and specific embodiments:
with reference to the attached figure 1, the invention provides a process for producing ethyl lactate by utilizing a reactive distillation dividing wall tower technology, a used reactive distillation dividing wall tower A is divided into seven areas which are respectively a full tower rectifying section B, a middle feeding side rectifying section C, a middle feeding side reaction section D, a middle feeding side stripping section E, a middle extraction side rectifying section F, a middle extraction side stripping section G and a tower kettle H, a clapboard I is arranged at the middle lower part of the tower to divide the middle section into a middle feeding side and a middle extraction side, the middle feeding side is respectively a middle feeding side rectifying section C, a middle feeding side reaction section D and a middle feeding side stripping section E from top to bottom, the middle extraction side is respectively a middle extraction side rectifying section F and a middle extraction side stripping section G from top to bottom, in order to meet the requirement that pressure drops at two sides of the middle section of the reaction rectifying bulkhead tower are consistent, the number of tower plates at the feeding side of the middle section is the same as that of tower plates at the extraction side of the middle section.
With reference to the attached drawing 2, a fresh lactic acid pipeline 1 of a high-boiling-point reactant is connected to the upper part of a middle-section feeding-side reaction section D of a reactive distillation bulkhead tower A, and a fresh ethanol pipeline 2 of a low-boiling-point reactant is connected to the lower part of the middle-section feeding-side reaction section D, so that ethanol in a liquid phase on a tower plate at the lower part of the middle-section feeding-side reaction section D is maintained at a high concentration, lactic acid in a liquid phase on a tower plate at the upper part of the middle-section feeding-side reaction section D is maintained at a high concentration, two reactants on the whole tower plate at the middle-section feeding-side reaction section D are maintained at relatively high concentrations, ethyl lactate and water generated by an esterification reaction are rapidly separated, ethyl lactate is enriched downwards, water is enriched.
Water generated by the esterification reaction of the middle feeding side reaction section D is enriched in the middle feeding side rectification section C and the whole tower rectification section B until the concentration of water at the top of the tower reaches a maximum value, mixed gas of water and ethanol enters a tower top condenser J in a tower top vapor phase pipeline 5, the mixed gas is condensed to a bubble point in the tower top condenser J and then flows back to a first tower plate of the whole tower rectification section B through a tower top reflux pipeline 6 to serve as tower top reflux, one part of liquid of the bottommost tower plate of the whole tower rectification section B enters the first tower plate of the middle feeding side rectification section C, and the other part of liquid enters the first tower plate of the middle extraction side rectification section F; because the vapor phase of the middle-section extraction side rectifying section F and the middle-section extraction side stripping section G does not contain ethanol, water is continuously enriched from top to bottom in the middle-section extraction side rectifying section F, the lowest part of the middle-section extraction side rectifying section F reaches the maximum value of a water concentration full tower, water is extracted from the system through an extracted water pipeline 3 between the middle-section extraction side rectifying section F and the middle-section extraction side stripping section G, and the rapid separation of ethyl lactate and water is ensured.
Separating ethyl lactate and ethanol generated by the esterification reaction in a stripping section E at the feed side of the middle section; the separation of ethyl lactate and water is completed in the middle-section extraction side stripping section G, and water is prevented from entering a tower kettle H ethyl lactate product; the tower bottom H is ethyl lactate, a part of the ethyl lactate enters a tower bottom reboiler K through a reboiler liquid phase pipeline 7, the ethyl lactate is heated by steam and then returns to the tower bottom H through a reboiler vapor phase pipeline 8 in a vapor phase mode to serve as a tower bottom vapor phase, and a part of the ethyl lactate is taken as a product and is extracted from an ethyl lactate product pipeline 4.
FIG. 3 is a process flow diagram of a reactive distillation dividing wall column using a vapor compression heat pump distillation technology, wherein a water and ethanol mixed gas enters a compressor L in an overhead vapor phase pipeline 5, the water and ethanol mixed gas is heated and pressurized under the compression action of the compressor L, and enters a tower kettle reboiler K through a compressor outlet pipeline 9, heat is provided for ethyl lactate in the tower kettle reboiler K, and meanwhile, the ethyl lactate is condensed, and condensate flows back to a first tower plate of a full-tower distillation section B through an overhead reflux pipeline 6 to serve as overhead reflux.
Example 1:
the structural parameters of the reaction rectifying bulkhead tower are shown in table 1, and the filling parameters of the macroporous sulfonic acid resin catalyst loaded in the reaction section at the feed side of the middle section are shown in table 2. Adding a certain amount of ethanol and zeolite into a reboiler at the bottom of the tower, heating the reboiler at the bottom of the tower, and rising water and ethanol gas to the reaction rectifying bulkhead tower after boiling. The pressure of the tower top is maintained to be 20kPaA, when liquid reflux exists at the tower top, fresh lactic acid and fresh ethanol with the mass content of 80% and 93% respectively are fed into the reaction rectification bulkhead tower through an injection pump, the feeding amount of the fresh lactic acid is 50ml/h, the molar ratio of alcohol acid feeding is 1.1:1, and the reaction rectification bulkhead tower reaches a stable state after 8 hours of operation. Under the condition, the water content of the ethyl lactate product extracted from the tower bottom is 0.11%, and the yield of the ethyl lactate is 97.32%.
TABLE 1 reactive distillation dividing wall column structural parameters
TABLE 2 catalyst loading parameters for the middle feed side reaction zone
Example 2:
the structural parameters and catalyst packing parameters of the reactive distillation dividing wall column were the same as in example 1. Adding a certain amount of ethanol and zeolite into a reboiler at the bottom of the tower, heating the reboiler at the bottom of the tower, and rising water and ethanol gas to the reaction rectifying bulkhead tower after boiling. The pressure at the top of the tower is maintained to be normal pressure, when liquid flows back at the top of the tower, fresh lactic acid and fresh ethanol with the mass content of 80% and 93% respectively are fed into the reaction rectification bulkhead tower through an injection pump, the feeding amount of the fresh lactic acid is 100ml/h, the molar ratio of alcohol acid feeding is 1.2:1, and the reaction rectification bulkhead tower reaches a stable state after 8 hours of operation. Under the condition, the water content of the ethyl lactate product extracted from the tower bottom is 0.14%, and the yield of the ethyl lactate is 90.46%.
Example 3:
the structural parameters and catalyst packing parameters of the reactive distillation dividing wall column were the same as in example 1. Adding a certain amount of ethanol and zeolite into a reboiler at the bottom of the tower, heating the reboiler at the bottom of the tower, and rising water and ethanol gas to the reaction rectifying bulkhead tower after boiling. The pressure of the tower top is maintained to be 60kPaA, when liquid reflux exists at the tower top, fresh lactic acid and fresh ethanol with the mass content of 80% and 93% respectively are fed into the reaction rectification bulkhead tower through a syringe pump, the feeding amount of the fresh lactic acid is 80ml/h, the molar ratio of alcohol acid feeding is 1.2:1, and the reaction rectification bulkhead tower reaches a stable state after 8 hours of operation. Under the condition, the water content of the ethyl lactate product extracted from the tower bottom is 0.08%, and the yield of the ethyl lactate is 94.63%.
The above examples are merely illustrative of the preferred embodiments of the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.
Claims (10)
1. A process method for producing ethyl lactate by a reactive distillation dividing wall tower technology is characterized by comprising the following steps: the production of ethyl lactate is completed in a reactive distillation bulkhead tower, the esterification reaction of lactic acid and ethanol is completed in a middle-section feeding-side reaction section of the reactive distillation bulkhead tower to generate ethyl lactate and water, the separation of ethanol and the esterification product water is completed through a middle-section extraction-side rectification section, meanwhile, the purification of ethyl lactate is realized in a middle-section feeding-side stripping section and a middle-section extraction-side stripping section, and finally, a food-grade ethyl lactate product is obtained at the bottom of the tower.
2. The process for producing ethyl lactate by the reactive distillation dividing wall column technology as claimed in claim 1, wherein: the reactive distillation dividing wall tower is divided into seven regions which are respectively a full-tower rectifying section, a middle feeding side reacting section, a middle feeding side stripping section, a middle extraction side rectifying section, a middle extraction side stripping section and a tower kettle, a partition plate is arranged at the middle lower part of the tower to divide the middle section into a middle feeding side and a middle extraction side, the middle feeding side sequentially respectively comprises the middle feeding side rectifying section, the middle feeding side reacting section and the middle extraction side stripping section from top to bottom, the middle extraction side sequentially comprises the middle extraction side rectifying section and the middle extraction side stripping section from top to bottom, the number of middle feeding side trays is the same as that of middle extraction side trays.
3. The process for producing ethyl lactate by the reactive distillation dividing wall column technology as claimed in claim 1, wherein: the fresh lactic acid pipeline is connected to the upper part of the middle feeding side reaction section, the fresh ethanol pipeline is connected to the lower part of the middle feeding side reaction section, and a produced water pipeline is arranged between the middle extraction side rectifying section and the middle extraction side stripping section.
4. The process for producing ethyl lactate by the reactive distillation dividing wall column technology as claimed in claim 1, wherein: the number of tower plates of the reaction distillation dividing wall tower is 25-90, wherein the number of tower plates of a rectifying section of the whole tower is 2-10, the number of tower plates of a rectifying section at a feeding side of a middle section is 5-20, the number of tower plates of a reaction section at a feeding side of the middle section is 15-50, the number of tower plates of a stripping section at a feeding side of the middle section is 3-10, the number of tower plates of a rectifying section at a collecting side of the middle section is 13-50, and the number of tower plates of a stripping section at a collecting side of the middle section is 10-30.
5. The process for producing ethyl lactate by the reactive distillation dividing wall column technology as claimed in claim 1, wherein: the operating pressure of the reactive distillation bulkhead tower is 20-101 kPaA, the temperature of the reaction section at the feed side of the middle section of the reactive distillation bulkhead tower is 70-120 ℃, the temperature of the top of the tower is 40-85 ℃, and the temperature of the bottom of the tower is 110-160 ℃.
6. The process for producing ethyl lactate by the reactive distillation dividing wall column technology as claimed in claim 3, wherein: the molar ratio of the fresh ethanol to the fresh lactic acid is 1.05-1.3: 1.
7. the process for producing ethyl lactate by the reactive distillation dividing wall column technology as claimed in claim 1, wherein: the reaction rectifying tower has plate column or packed column, floating valve, bubble cap or sieve plate as column plate, and regular or random packing as packing.
8. The process for producing ethyl lactate by reactive distillation dividing wall column technique as claimed in claim 1, wherein: the tower plate or filler of the reaction rectifying tower partition wall tower is made of any one of metal, ceramic, polytetrafluoroethylene and plastic.
9. The process for producing ethyl lactate by reactive distillation dividing wall column technique as claimed in claim 1, wherein: the solid catalyst loaded on the reaction section at the feed side of the middle section of the reactive distillation bulkhead tower is macroporous sulfonic acid resin or super-strong solid acid catalyst.
10. The process for producing ethyl lactate by reactive distillation dividing wall column technique as claimed in claim 1, wherein: the vapor phase at the top of the tower is compressed by a compressor, and then the vapor phase is heated and pressurized, and then exchanges heat with a reboiler at the bottom of the tower to provide heat.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111943849A (en) * | 2020-08-15 | 2020-11-17 | 天津大学 | High-efficiency energy-saving ethyl lactate reaction rectification production method and device |
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