CN213050530U - High-efficiency energy-saving ethyl lactate reaction rectification production device - Google Patents
High-efficiency energy-saving ethyl lactate reaction rectification production device Download PDFInfo
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Abstract
The invention relates to a high-efficiency energy-saving ethyl lactate reaction rectification production device, which is independently realized by a reaction rectification tower and a product refining tower or a reaction rectification tower which is completely thermally coupled with a bulkhead tower; the device comprises a reaction rectifying tower, a product refining tower, a lactic acid feed inlet, an ethanol feed outlet, a product refining tower, a product recovery tower, a product recycle tower and a product raw material lactic acid pipeline, wherein the lactic acid feed inlet is arranged at the top of the reaction section of the reaction rectifying tower, the ethanol feed inlet is arranged at the bottom of the reaction section of the. Lactic acid and ethanol enter a product refining unit after the reaction and rectification process, so that a high-purity ethyl lactate product is obtained, and the lactic acid is extracted from a tower kettle and circulated to the reaction and rectification unit. The invention has the advantages that the quality purity of the product can reach more than 99 percent, and the yield can reach more than 98 percent. The reaction rectifying tower and the product refining tower are coupled and integrated by a complete thermal coupling method, so that the production energy consumption is saved by more than 30%, and the equipment investment cost is saved.
Description
Technical Field
The invention relates to the technical field of synthesis of an organic solvent ethyl lactate in the field of chemical industry, in particular to a high-efficiency energy-saving ethyl lactate reaction rectification production device; the device for producing ethyl lactate by utilizing the reactive distillation technology under the lactic acid circulation condition has high efficiency and energy saving.
Background
Solvents are widely used in almost all production and process industries. The common solvent is mainly produced by using non-renewable petroleum as a raw material, a large amount of carbon dioxide and volatile organic pollutants (VOCs) are released in the production process, and the ethyl lactate organic solvent replaces the traditional solvent (such as halogenated solvents, ethers, chlorofluorocarbon solvents and the like) to play a vital role in reducing carbon/pollution emission in China.
Ethyl lactate, also known as alpha-hydroxypropionic acid ethyl ester, has a molecular formula of C5H10O3The melting point is 26 ℃, the boiling point is 154.5 ℃, the solvent is a green environment-friendly solvent, has good biodegradability, and can be widely applied to different chemical fields such as spices, solvents, lubricants, plasticizers and the like. The ethyl lactate is colorless and slightly odorous liquid, naturally exists in fruits such as pineapples, oranges, apples and the like, has good solubility, is miscible with water, and can be dissolved in alcohol, aromatic hydrocarbon, ester, hydrocarbon and oil. According to the reports of the U.S. department of energy, more than 80% of conventional solvents (especially halogenated hydrocarbons) will be replaced by ethyl lactate in the world in the future, and the production method has high energy consumption and high cost, so that the wide application in industry is limited, and the development of energy-saving, low-cost and environment-friendly ethyl lactate production method is urgent.
At present, the traditional process for producing ethyl lactate mainly adopts lactic acid and ethanol as raw materials, firstly generates ethyl lactate through catalytic reaction, and then purifies the ethyl lactate in the reaction product and recovers unreacted raw materials through rectification or flash separation procedures after the reaction is finished. The traditional production has the problems of longer process route, higher investment cost and the like, so the reactive distillation process is generated successively, the catalytic reaction and the distillation separation are integrated in the same equipment, the cost is reduced, in order to improve the conversion rate of the reaction, the excessive ethanol and water are adopted to form an azeotrope to be extracted from the top of the tower to promote the forward reaction, and the residual ethanol is recycled by the distillation mode. The ethanol residue in the process results in long subsequent separation flow, high energy consumption for separating the ethanol and water azeotrope and low yield of ethyl lactate. Patents and literature on ethyl lactate reaction processes are reported below:
patent CN100427453C proposes a new process for synthesizing ethyl lactate by a catalytic distillation method, lactic acid and ethanol react in a catalytic section of a catalytic distillation tower filled with a strong acid ion exchange resin catalyst to generate ethyl lactate, and tower bottoms are subjected to impurity removal by a flash tower to obtain an ethyl lactate product. According to the method, the molar ratio of ethanol to lactic acid is 3: 1-5: 1, the temperature of a reboiler at a tower kettle is 80-90 ℃, so that the tower kettle liquid still contains water and unreacted ethanol, the separation of the water and the ethanol from ethyl lactate is not realized, and the yield of subsequent separation products is reduced.
Patent CN1110698340A provides a process method for producing ethyl lactate by utilizing a reactive distillation dividing wall tower technology, wherein the whole tower is divided into seven areas, a whole 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 are arranged, ethyl lactate and water are generated in the middle section feeding side reaction section, the middle section extraction side rectifying section completes the separation of ethanol and esterified product water, products are purified in the two stripping sections of the feeding side and the extraction side, and ethyl lactate products are obtained at the bottom of the tower. The tower has more areas and more complex design, the molar ratio of fresh ethanol to lactic acid is 1.05-1.3: 1, and the energy consumption for separating the ethanol from the water azeotrope is higher.
Patent CN109438228A proposes that energy consumption is reduced by using reaction-pervaporation membrane-distillation technology, product quality is guaranteed, and lactic acid and ethanol are concentrated in H2SO4The method is characterized in that a catalyst is heated and pressurized under a stirring state to esterify and synthesize ethyl lactate, mixed steam of ethanol, water and a small amount of ethyl lactate output by an esterification reaction is fractionated by a fractionating tower, the mixed steam of the ethanol and the water is input into a pervaporation membrane to carry out water separation, and the separated ethanol steam is output from the pervaporation membrane to continuously participate in the reaction. After the esterification reaction is finished, sodium carbonate is added to neutralize concentrated H2SO4And cooling the esterification liquid and then carrying out reduced pressure distillation to obtain the ethyl lactate product. The catalyst is concentrated H2SO4Side reactions are easy to occur, the product yield is reduced, more three wastes are generated, the recycling is difficult, the process flow is complex, and the investment and operation cost is high.
Patent CN107032984A discloses a continuous ethyl lactate synthesis method, which comprises two working sections of reaction and separation, wherein the molar ratio of ethanol to lactic acid is 2: 1-4: 1, the raw material is pumped into a fixed bed reactor to perform catalytic esterification reaction to obtain an ethyl lactate crude product, and then the ethyl lactate crude product sequentially enters a rough separation tower, an ethanol tower, a lactic acid tower and an ethyl lactate tower to obtain food-grade ethyl lactate. The method has the advantages of longer process flow, higher equipment investment and operation cost, azeotropic formation of ethanol and water, and higher recovery energy consumption caused by excessive ethanol.
J.GaoX.M.ZHao, L.Y.ZHou, Z.H.Huang, Investigation of Ethyl Lactate Reactive partitioning Process, Chemical Engineering Research and Design,2007,85(4):525 and 529. Synthesis of Ethyl Lactate by catalytic rectification technique with ultra-fine magnetic solid super acid SO4 2-/ZrO2–Fe3O4The method for simulating and experimentally comparing the catalyst is used for verifying the feasibility of producing ethyl lactate by a reactive distillation method, water and ethanol are extracted from the top of the tower in an azeotrope form, and the product ethyl lactate is obtained from the bottom of the tower. The yield of the ethyl lactate is improved by 82 percent compared with that of a simple esterification reactor, but the conversion rate of raw materials and the yield of products are still lower.
In order to further reduce energy consumption, improve product yield and reduce cost, the feeding molar ratio is 1:1, reactants are utilized to the maximum extent, and the significance of saving energy is great by adopting high-efficiency energy-saving ethyl lactate to produce ethyl lactate through reaction and rectification.
Disclosure of Invention
The invention aims to provide a reaction rectification device suitable for efficient and energy-saving production of ethyl lactate.
The high-efficiency energy-saving ethyl lactate reaction rectification production device is independently realized by a reaction rectification tower and a product refining tower or a reaction rectification tower which is completely thermally coupled with a bulkhead tower; the device comprises a reaction rectifying tower, a product refining tower, a lactic acid feed inlet, an ethanol feed outlet, a product refining tower, a product recovery tower, a product recycle tower and a product raw material lactic acid pipeline, wherein the lactic acid feed inlet is arranged at the top of the reaction section of the reaction rectifying tower, the ethanol feed inlet is arranged at the bottom of the reaction section of the.
And (3) discharging product water from the top of the reaction rectifying tower, obtaining a high-purity ethyl lactate product from the top of the product refining tower, collecting lactic acid from the tower bottom, circulating the lactic acid to the reaction rectifying tower, and returning the lactic acid serving as a raw material to the reaction rectifying tower after being converged with a fresh raw material.
The invention relates to a high-efficiency energy-saving ethyl lactate reaction rectification production device; the method is realized independently by adopting a reaction rectifying tower and a product refining tower or a reaction rectifying tower which is completely thermally coupled with a bulkhead tower; raw materials of lactic acid and ethanol respectively enter a reaction rectification zone from the top and the bottom of a reaction section, and product water and ethyl lactate are moved out of the reaction rectification zone while esterification is carried out under catalysis of the reaction rectification zone, so that reactant ethanol is completely converted; the unreacted lactic acid and the product ethyl lactate are separated by a product refining process, so that the reactant lactic acid is recycled to the reaction rectification zone, and the molar ratio of the lactic acid to the ethanol in the reaction rectification zone is ensured to be at a higher value; and finally discharging the water product from the top of the reactive distillation tower, and obtaining a high-purity ethyl lactate product at the top of the product refining unit tower.
The production device consists of a reaction rectifying tower (3) and a product refining tower (17); the reactive distillation tower (3) consists of a distillation section (4), a reaction section (5) and a stripping section (6); the product refining tower (17) consists of a product refining tower rectifying section (18) and a product refining tower stripping section (19); the two-tower device comprises a reaction rectifying tower (3), a product refining tower (17), a tower top water condenser (8), a tower top ethyl lactate condenser (21), a tower bottom crude product reboiler (14), a tower bottom lactic acid reboiler (27), related feeding pipelines and pipelines for connecting the devices; a lactic acid (1) feeding pipeline is connected to the top of a reaction section (5) of a reaction rectifying tower (3), an ethanol (2) feeding pipeline is connected to the bottom of the reaction section (5) of the reaction rectifying tower (3), gas phase water (7) at the top of the reaction rectifying tower (3) is connected with a gas phase inlet of a tower top water condenser (8) through a pipeline, a condensed liquid phase water (9) material extraction pipeline is connected with a liquid phase outlet of the tower top water condenser (8), meanwhile, a part of reflux water (10) at the liquid phase outlet of the tower top water condenser (8) is connected with the top of the reaction rectifying tower (3) through a pipeline, and the other part of fractionated effluent (11) is extracted for removed light components; the bottom of the reaction rectifying tower (3) is connected with the inlet of a product refining tower (17) through a crude product extraction (16) pipeline, the steam at the top of the product refining tower (17) is connected with the gas inlet of a tower top ethyl lactate condenser (21) through a gas phase ethyl lactate (20) pipeline, after condensation, one part of reflux ethyl lactate (23) returns to the top of the product refining tower (17), the other part of high-purity ethyl lactate (24) is extracted from the top of the tower as a product, and one part of circulating lactic acid (29) material of the liquid phase product at the bottom of the product refining tower (17) is extracted and returned to the top of the reaction section (5) of the reaction rectifying tower (3).
The internals of the rectifying section (4) and the stripping section (6) of the reactive rectifying tower (3) are both packing or trays, and the internals of the reactive rectifying tower (5) are regular loaded molecular sieve type catalytic separation internal components or catalytic packing or a combination form thereof; the internals of the product refining tower (17) are all packing or trays.
The number of tower plates of the reactive distillation tower is 20-50, wherein the number of tower plates of the distillation section is 5-15, the number of tower plates of the reaction section is 10-40, and the number of tower plates of the stripping section is 2-15; the number of tower plates of the product refining tower is 10-20, wherein the number of tower plates of the rectifying section is 5-9, and the number of tower plates of the stripping section is 7-15.
The production device is independently realized by a reaction rectification complete thermal coupling bulkhead tower (30), and the reaction rectification complete thermal coupling bulkhead tower (30) consists of a main tower rectification section (31), a main tower reaction section (32), a main tower stripping section (33), an auxiliary tower rectification section (34) and an auxiliary tower stripping section (35); comprises a reaction rectification fully thermally coupled dividing wall column (30), an overhead water condenser (8), an overhead ethyl lactate condenser (21), a tower bottom lactic acid reboiler (27), related feed pipelines and pipelines for connecting the above devices; a lactic acid (1) feeding pipeline is connected to the top of a main tower reaction section (32) of a reaction rectification complete thermal coupling bulkhead tower (30), an ethanol (2) feeding pipeline is connected to the bottom of the main tower reaction section (32) of the reaction rectification complete thermal coupling bulkhead tower (30), gas phase water (7) at the top of the main tower of the reaction rectification complete thermal coupling bulkhead tower (30) is connected with a gas phase inlet of a tower top water condenser (8) through a pipeline, a condensed liquid phase water (9) material extraction pipeline is connected with a liquid phase outlet of the tower top water condenser (8), meanwhile, a part of reflux water (10) at the liquid phase outlet of the tower top water condenser (8) is connected with the top of the main tower of the reaction rectification complete thermal coupling bulkhead tower (30) through a pipeline, and the other part of fractionated effluent (11) is discharged for removed light components; the gas phase ethyl lactate (20) at the top of the auxiliary tower of the reactive distillation complete thermal coupling partition tower (30) is connected with a gas phase inlet of an ethyl lactate condenser (21) at the top of the tower through a pipeline, a material extraction pipeline of liquid phase ethyl lactate (22) is connected with a liquid phase outlet of the ethyl lactate condenser (21) at the top of the tower, meanwhile, one part of reflux ethyl lactate (23) at the liquid phase outlet of the ethyl lactate condenser (21) at the top of the tower is connected with the top of the auxiliary tower of the reactive distillation complete thermal coupling partition tower (30) through a pipeline, and the other part of high-purity ethyl lactate (24) is extracted from; the liquid phase lactic acid (26) returned from the tower bottom of the reaction rectification complete thermal coupling partition wall tower (30) is connected with the liquid phase inlet of the tower bottom lactic acid reboiler (27) through a pipeline, meanwhile, the gas phase outlet of the tower bottom lactic acid reboiler (27) is also connected with the tower bottom of the reaction rectification complete thermal coupling partition wall tower (30) through a tower return gas phase lactic acid (28) pipeline, and the other part of circulating lactic acid (29) material is extracted as a raw material to be converged with the lactic acid (1) and then returned to the top of the main tower reaction section (32) of the reaction rectification complete thermal coupling partition wall tower (30).
The reaction rectification is completely thermally coupled with a partition wall tower (30), the middle part of the partition wall tower is provided with a partition wall, the upper part of the partition wall tower is capped, a tower body is divided into a main tower and an auxiliary tower, a reaction zone is positioned in the main tower, a product refining zone is positioned in the auxiliary tower, and the tower needs two condensers which are a tower top water condenser (8), a tower top ethyl lactate condenser (21) and a tower bottom lactic acid reboiler (27) respectively; the internal parts of the main tower rectifying section (31), the main tower stripping section (33), the auxiliary tower rectifying section (34) and the auxiliary tower stripping section (35) are all packing or trays, and the internal parts of the main tower reaction section (32) are regular load molecular sieve type catalytic separation internal components or catalytic packing or a combination form of the regular load molecular sieve type catalytic separation internal components or the catalytic packing.
The total number of the tower plates of the reaction rectification complete thermal coupling dividing wall tower is 40-80, wherein the number of the tower plates of the rectification section of the main tower is 5-10, the number of the tower plates of the reaction section of the main tower is 10-40, the number of the tower plates of the stripping section of the main tower is 5-13, the number of the tower plates of the rectification section of the auxiliary tower is 10-20, and the number of the tower plates of the stripping section of the auxiliary tower is 10-15.
The method and the device are characterized in that a structure-activity relationship between a catalytic filler structure and catalytic performance, matching of reaction and separation, optimization of theoretical plate number and retention time are studied in detail through a method combining experiments and numerical simulation, the initial feeding molar ratio of lactic acid to ethanol is 2-4: 1, lactic acid and product ethyl lactate which are not completely reacted are separated through a product refining process through the design of a reaction rectification process, the recovery and circulation of reactant lactic acid to a reaction rectification area are realized, the molar ratio of lactic acid to ethanol is increased in the reaction area, the complete reaction is realized under the condition that the steady feeding molar ratio of lactic acid to ethanol is 1:1, and the problem of azeotropic separation of the ethanol and product water which are not completely reacted is solved. Further, the reaction rectifying tower and the product refining tower are thermally coupled and integrated, so that the aim of saving energy is fulfilled.
The technology of the invention is as follows:
the high-efficiency energy-saving ethyl lactate reaction rectification production method comprises the following steps: production raw materials of lactic acid and ethanol respectively enter a reaction rectification zone from the top and the bottom of a reaction section, and the product water and ethyl lactate are rapidly moved out of the reaction rectification zone while esterification is carried out in a catalytic separation inner member of the reaction rectification zone, so that reactant ethanol is completely converted; the unreacted lactic acid and the product ethyl lactate are separated by a product refining process, so that the reactant lactic acid is recycled to the reaction rectification zone, and the molar ratio of the lactic acid to the ethanol in the reaction rectification zone is ensured to be at a higher value; and finally discharging the water product from the top of the reactive distillation tower, and obtaining a high-purity ethyl lactate product at the top of the product refining unit tower.
The operating process conditions of the high-efficiency energy-saving ethyl lactate reaction rectification production method are as follows:
the operating pressure of the reactive distillation process is 40-101 kPa; the reflux ratio of the reactive distillation process is 1-10.
The operating pressure of the product refining process is 100 Pa-5 kPa; the reflux ratio is 0.5 to 3.
The residence time of each theoretical stage of reaction materials in the reaction zone is 20-70 seconds.
The catalyst loading on each theoretical plate of the reaction rectification zone is 0.1-0.6 cm3Catalyst/cm3A catalytic filler.
The feeding molar ratio of the initial lactic acid to the ethanol is 2-4: 1, when the process reaches a stable state, the lactic acid which is not completely reacted circulates in the reaction rectifying tower, the stable feeding molar ratio of the lactic acid to the ethanol is 1:1, and the molar ratio of the reactant lactic acid to the ethanol in the reaction rectifying zone is 2-4: 1.
The high-efficiency energy-saving ethyl lactate reaction rectification production device is characterized in that: the production raw material lactic acid pipeline is connected to the upper part of the reaction section, the production raw material ethanol pipeline is connected to the bottom of the reaction section, the top of the product refining tower is provided with an extracted ethyl lactate pipeline, the bottom of the product refining tower is provided with an extracted circulating lactic acid pipeline, and the circulating lactic acid pipeline is connected with the production raw material lactic acid pipeline.
The invention relates to a method and a device for producing ethyl lactate by using an efficient energy-saving reaction rectification technology. Lactic acid and ethanol enter a product refining unit after the reaction and rectification process, so that a high-purity ethyl lactate product is obtained, and the lactic acid is extracted from a tower kettle and circulated to the reaction and rectification unit. The invention has the advantages that the quality purity of the product can reach more than 99 percent, and the yield can reach more than 98 percent. The reaction rectifying tower and the product refining tower are coupled and integrated by a complete thermal coupling method, so that the production energy consumption is saved by more than 30%, and the equipment investment cost is saved.
Drawings
FIG. 1 is a schematic diagram of a process flow of high-efficiency energy-saving ethyl lactate reaction rectification production, which consists of a reaction rectification tower (3) and a product refining tower (17).
FIG. 2 is a schematic diagram of the process flow of the high-efficiency energy-saving ethyl lactate reaction distillation production, which consists of a reaction distillation complete thermal coupling bulkhead tower (30).
Wherein: 1-lactic acid; 2-ethanol; 3-a reactive distillation column; 4-a rectification section; 5-a reaction section; 6-stripping section; 7-gas phase water; 8-tower top water condenser; 9-liquid phase water; 10-refluxing water; 11-distilling off water; 12-crude product at the bottom of the tower; 13-returning the crude product to the tower; 14-bottom crude product reboiler; 15-returning to the tower to obtain a gas-phase crude product; 16-extracting a crude product; 17-a product refining column; 18-a rectification section of a product refining tower; 19-a stripping section of a product refining tower; 20-gas phase ethyl lactate; 21-overhead ethyl lactate condenser; 22-liquid phase ethyl lactate; 23-refluxing ethyl lactate; 24-high purity ethyl lactate; 25-liquid phase lactic acid at the bottom of the tower; 26-reflux liquid phase lactic acid; 27-bottom lactic acid reboiler; 28-refluxing the column with the gas phase lactic acid; 29-recycle lactic acid; 30-reactive distillation fully thermally coupled dividing wall column; 31-a main column rectification section; 32-a main column reaction section; 33-main column stripping section; 34-a rectifying section of a side column; 35-side column stripping section.
Detailed Description
The method and the device provided by the invention are further explained in the following with the attached drawings.
The invention is realized by the following technical scheme:
as shown in figure 1, lactic acid (1) is fed from the top of a reaction section (5) in a reaction rectifying tower (3), ethanol (2) is fed from the bottom of the reaction section (5) in the reaction rectifying tower (3), liquid-phase lactic acid and ethanol vapor entering the tower carry out esterification reaction in the reaction section (5), generated water enters a tower top water condenser (8) from an outlet of gas-phase water (7) at the tower top of the reaction rectifying tower (3) for condensation, the condensed material flows out from a liquid-phase outlet of the tower top water condenser (8), a part of liquid-phase water (9) flows into the reaction rectifying tower (3) as tower top reflux water (10), the other part of fractionated effluent water (11) is discharged as removed light components, unreacted lactic acid and generated ethyl lactate return to a tower liquid-phase crude product (13) from a tower bottom liquid-phase outlet of the reaction rectifying tower (3) and enter a crude product reboiler (14), the other part is taken as a crude product to be extracted (16), the crude product extracted (16) at the bottom of the reaction rectifying tower (3) enters a product refining tower (17), gas-phase ethyl lactate (20) at the top of the product refining tower (17) is condensed by an ethyl lactate condenser (21) at the top of the tower and then flows out, one part of liquid-phase ethyl lactate (22) is taken as reflux ethyl lactate (23) at the top of the product refining tower (17) and the other part of high-purity ethyl lactate (24) is taken as a product to be extracted, one part of liquid-phase lactic acid (25) at the bottom of the tower returns to the bottom of the product refining tower (17) through a lactic acid reboiler (27) at the bottom of the tower, and the other part of circulating lactic acid (29) is taken as a raw material to be merged with lactic acid (1) and then returns to the top of a reaction section (.
As shown in fig. 2, lactic acid (1) is fed from the top of a reaction section (32) in a reaction rectification complete thermal coupling bulkhead column (30), ethanol (2) is fed from the bottom of the reaction section (2) in the reaction rectification complete thermal coupling bulkhead column (30), liquid phase lactic acid and ethanol vapor entering the column are subjected to esterification reaction in the reaction section (2), generated water enters a column top water condenser (8) from a gas phase outlet at the top of a main column of the reaction rectification complete thermal coupling bulkhead column (30) for condensation, the condensed material flows out from a liquid phase outlet of the column top water condenser (8), a part of liquid phase water (9) flows into the main column of the reaction rectification complete thermal coupling bulkhead column (30) as column top reflux water (10), and the other part of fractionated effluent (11) is discharged as removed light components; the product ethyl lactate enters an ethyl lactate condenser (21) at the top of the tower from a gas phase outlet at the top of the auxiliary tower of the reaction rectification complete thermal coupling partition tower (30) for condensation, the condensed material flows out from a liquid phase outlet of the ethyl lactate condenser (21) at the top of the tower, one part of the liquid phase ethyl lactate (22) flows into the auxiliary tower of the reaction rectification complete thermal coupling partition tower (30) as reflux ethyl lactate (23) at the top of the tower, and the other part of the high-purity ethyl lactate (24) is taken as the product ethyl lactate and is extracted from the top of the auxiliary tower of the reaction rectification complete thermal coupling partition tower (30); part of the liquid phase lactic acid (25) at the bottom of the reaction rectification complete thermal coupling bulkhead tower (30) returns to the liquid phase lactic acid (26) through a tower bottom lactic acid reboiler (27) and returns to the bottom of the reaction rectification complete thermal coupling bulkhead tower (30), and the other part of the circulating lactic acid (29) is collected as a raw material and is converged with the lactic acid (1) and then returns to the top of a main tower reaction section (32) of the reaction rectification complete thermal coupling bulkhead tower (30).
The operating process conditions of the high-efficiency energy-saving ethyl lactate reaction rectification production method are as follows: the operating pressure of the reactive distillation process is 40-101 kPa; the reflux ratio of the reactive distillation process is 1-10. The operating pressure of the product refining process is 100 Pa-5 kPa; the reflux ratio is 0.5 to 3. The residence time of each theoretical stage of reaction materials in the reaction zone is 20-70 seconds. The molar ratio of the reactant lactic acid to the ethanol in the reaction rectification zone is 2-4: 1.
If the device consists of two towers, namely a reaction rectifying tower (3) and a product rectifying tower (17), the reaction rectifying tower (3) consists of a reaction rectifying tower rectifying section (4), a reaction rectifying tower reaction section (5) and a reaction rectifying tower stripping section (6); the product refining tower (17) consists of a product refining tower rectifying section (18) and a product refining tower stripping section (19). The two-tower device comprises a reaction rectifying tower (3), a product refining tower (21), an overhead water condenser (8), an overhead ethyl lactate condenser (25), a tower bottom crude product reboiler (14), a tower bottom lactic acid reboiler (27), related feeding pipelines and pipelines for connecting the devices; a feeding pipeline of lactic acid (1) is connected to the top of a reaction section (5) of a reaction rectifying tower (3), a feeding pipeline of ethanol (2) is connected to the bottom of the reaction section (5) of the reaction rectifying tower (3), gas phase water (7) at the top of the reaction rectifying tower (3) is connected with a gas phase inlet of a tower top water condenser (8) through a pipeline, a condensed liquid phase water (9) material pipeline is connected with a liquid phase outlet of the tower top water condenser (8), meanwhile, a part of backflow water (10) at the liquid phase outlet of the tower top water condenser (8) is connected with the top of the reaction rectifying tower (3) through a pipeline, and the other part of fractionated effluent (11) is extracted for removed light components. The bottom of the reaction rectifying tower (3) is connected with the inlet of a product refining tower (17) through a crude product extraction (16) pipeline, the steam at the top of the product refining tower (17) is connected with the gas inlet of a tower top ethyl lactate condenser (21) through a gas phase ethyl lactate (20) pipeline, after condensation, one part of reflux ethyl lactate (23) returns to the top of the product refining tower (17), the other part of high-purity ethyl lactate (24) is extracted from the top of the tower as a product, and one part of circulating lactic acid (29) material of the liquid phase product at the bottom of the product refining tower (17) is extracted and returned to the top of the reaction section (5) of the reaction rectifying tower (3).
If the device is realized by a reaction rectification complete thermal coupling bulkhead column (30) and a column independently, the reaction rectification complete thermal coupling bulkhead column (30) consists of a main column rectification section (31), a main column reaction section (32), a main column stripping section (33), an auxiliary column rectification section (34) and an auxiliary column stripping section (35). The tower device comprises a reaction rectification fully thermally coupled bulkhead tower (30), an overhead water condenser (8), an overhead ethyl lactate condenser (25), a tower bottom lactic acid reboiler (27), related feed pipelines and pipelines for connecting the devices; a feeding pipeline of lactic acid (1) is connected to the top of a main column reaction section (32) of a reaction rectification complete thermal coupling bulkhead column (30), a feeding pipeline of ethanol (2) is connected to the bottom of the main column reaction section (32) of the reaction rectification complete thermal coupling bulkhead column (30), gas phase water (7) at the top of the main column of the reaction rectification complete thermal coupling bulkhead column (30) is connected with a gas phase inlet of a column top water condenser (8) through a pipeline, a material pipeline of condensed liquid phase water (9) is connected with a liquid phase outlet of the column top water condenser (8), meanwhile, a part of reflux water (10) at the liquid phase outlet of the column top water condenser (8) is connected with the top of the main column of the reaction rectification complete thermal coupling bulkhead column (30) through a pipeline, and the other part of fractionated effluent (11) is discharged for removed light components. The gas phase ethyl lactate (20) at the top of the auxiliary tower of the reactive distillation complete thermal coupling partition tower (30) is connected with a gas phase inlet of an ethyl lactate condenser (21) at the top of the tower through a pipeline, a material extraction pipeline of liquid phase ethyl lactate (22) is connected with a liquid phase outlet of the ethyl lactate condenser (21) at the top of the tower, meanwhile, one part of reflux ethyl lactate (23) at the liquid phase outlet of the ethyl lactate condenser (21) at the top of the tower is connected with the top of the auxiliary tower of the reactive distillation complete thermal coupling partition tower (30) through a pipeline, and the other part of high-purity ethyl lactate (24) is extracted from the. The liquid phase lactic acid (26) returned from the tower bottom of the reaction rectification complete thermal coupling partition wall tower (30) is connected with the liquid phase inlet of the tower bottom lactic acid reboiler (27) through a pipeline, meanwhile, the gas phase outlet of the tower bottom lactic acid reboiler (27) is also connected with the tower bottom of the reaction rectification complete thermal coupling partition wall tower (30) through a tower return gas phase lactic acid (28) pipeline, and the other part of circulating lactic acid (29) material is extracted as a raw material to be converged with the lactic acid (1) and then returned to the top of the main tower reaction section (32) of the reaction rectification complete thermal coupling partition wall tower (30).
The high-efficiency energy-saving ethyl lactate reaction rectification production device is characterized in that: the production raw material lactic acid pipeline is connected to the upper part of the reaction section, the production raw material ethanol pipeline is connected to the bottom of the reaction section, the top of the product refining tower is provided with an extracted ethyl lactate pipeline, the bottom of the product refining tower is provided with an extracted circulating lactic acid pipeline, and the circulating lactic acid pipeline is connected with the production raw material lactic acid pipeline.
As shown in figure 1, the method is applied to examples 1 and 2, the internals of the rectifying section (4) and the stripping section (6) of the reactive rectifying tower (3) are both packing or trays, and the internals of the reactive rectifying tower (5) are regular-load molecular sieve type catalytic separation internals or catalytic packing or a combination form of the regular-load molecular sieve type catalytic separation internals or the catalytic packing; the internals of the product refining tower (17) are all packing or trays. The number of tower plates of the reactive distillation tower is 20-50, wherein the number of tower plates of the distillation section is 5-15, the number of tower plates of the reaction section is 10-40, and the number of tower plates of the stripping section is 2-15; the number of tower plates of the product refining tower is 10-20, wherein the number of tower plates of the rectifying section is 5-9, and the number of tower plates of the stripping section is 7-15. Or as shown in figure 2, applied to the embodiments 3 and 4, the reaction rectification complete thermal coupling bulkhead column (30) is provided with a bulkhead in the middle, the upper part of the bulkhead is capped, the column body is divided into a main column and an auxiliary column, the reaction area is positioned in the main column, the product refining area is positioned in the auxiliary column, and the column needs two condensers, namely an overhead water condenser (8), an overhead ethyl lactate condenser (21) and a bottom lactic acid reboiler (27). A main tower rectifying section (31), a main tower stripping section (33) and an auxiliary towerThe internals of the rectifying section (34) and the stripping section (35) of the auxiliary column are both packing or trays, and the internals of the reaction section (32) of the main column are regular-loaded molecular sieve type catalytic separation internals or catalytic packing or a combination form thereof. The total number of the tower plates of the reaction distillation complete thermal coupling dividing wall tower is 40-80, wherein the number of the tower plates of the distillation section of the main tower is 5-10, the number of the tower plates of the reaction section of the main tower is 10-40, the number of the tower plates of the stripping section of the main tower is 5-13, the number of the tower plates of the distillation section of the auxiliary tower is 10-20, and the number of the tower plates of the stripping section of the auxiliary tower is 10-15. The catalyst loading on each theoretical plate of the reaction rectification zone is 0.1-0.6 cm3Catalyst/cm3A catalytic filler.
The technology and equipment of the invention are widely applied to the process of preparing ethyl lactate by esterifying lactic acid and ethanol, and in order to better illustrate the advantages of the invention in terms of product purity and yield, the invention is compared with the process described in patent CN 100427453C. Four of these examples of applications were chosen for illustration, but are not intended to limit the scope of applicability of the present techniques and apparatus.
Example 1
The method is used for the process of preparing ethyl lactate by esterifying lactic acid and ethanol, is the same as the process of the invention, and comprises a reaction rectifying tower, a product refining tower, a tower top water condenser, a tower top ethyl lactate condenser, a tower bottom crude product reboiler and a tower bottom lactic acid reboiler, wherein the operation pressure of the reaction rectifying tower is 101kPa, the reflux ratio is 9, the feeding amount of lactic acid is 50kmol/h, the reaction molar ratio of biomass-based lactic acid to ethanol is 2, and the loading amount of a catalyst is 0.1cm3Catalyst/cm3The operation pressure of the catalytic filler and the product refining tower is 5kpa, and the reflux ratio is 0.5.
After the process, the purity of the main product ethyl lactate can reach 99%, the yield can reach 98.2%, and compared with the conventional reaction rectification process, the energy consumption can be reduced by more than 30%.
Example 2
The method is used for the process of preparing the ethyl lactate by esterifying the lactic acid and the ethanol, and comprises a reaction rectifying tower, a product refining tower, a tower top water condenser, a tower top ethyl lactate condenser, a tower bottom crude product reboiler and a tower, wherein the process is the same as the process of the inventionA bottom lactic acid reboiler, wherein the operating pressure of the reaction rectifying tower is 40kPa, the reflux ratio is 10, the feeding amount of lactic acid is 15kmol/h, the reaction molar ratio of biomass-based lactic acid to ethanol is 3, and the loading amount of the catalyst is 0.1cm3Catalyst/cm3The catalytic packing, the operating pressure of the product refining tower is 100pa, and the reflux ratio is 1.
After the process, the purity of the main product ethyl lactate can reach 99.2%, the yield can reach 98.3%, and compared with the conventional reaction rectification process, the energy consumption can be reduced by more than 30%.
Example 3
The method is used for the process of preparing ethyl lactate by esterifying lactic acid and ethanol, is the same as the process of the invention, and comprises a reaction rectification complete thermal coupling bulkhead tower, a tower top water condenser, a tower top ethyl lactate condenser and a tower bottom lactic acid reboiler, wherein the operation pressure of the reaction rectification complete thermal coupling bulkhead tower is 50kPa, the reflux ratio of a main tower is 2, the reflux ratio of an auxiliary tower is 3, the feeding amount of lactic acid is 30kmol/h, the reaction molar ratio of biomass-based lactic acid and ethanol is 4, and the loading amount of a catalyst is 0.1cm3Catalyst/cm3A catalytic filler.
After the process, the purity of the main product ethyl lactate can reach 99.7%, the yield can reach 98.6%, and compared with the conventional reaction rectification process, the energy consumption can be reduced by more than 40%.
Example 4
The method is used for the process of preparing ethyl lactate by esterifying lactic acid and ethanol, is the same as the process of the invention, and comprises a reaction rectification complete thermal coupling bulkhead tower, a tower top water condenser, a tower top ethyl lactate condenser and a tower bottom lactic acid reboiler, wherein the operation pressure of the reaction rectification complete thermal coupling bulkhead tower is 40kPa, the reflux ratio of a main tower is 1.5, the reflux ratio of an auxiliary tower is 2.5, the feeding amount of lactic acid is 15kmol/h, the reaction molar ratio of biomass-based lactic acid and ethanol is 3, and the loading amount of a catalyst is 0.1cm3Catalyst/cm3A catalytic filler.
After the process, the purity of the main product ethyl lactate can reach 99.3%, the yield can reach 98.2%, and compared with the conventional reaction rectification process, the energy consumption can be reduced by more than 30%.
The efficient and energy-saving ethyl lactate reaction rectification production method and device provided by the invention have been described through the preferred embodiments, and it is obvious for related technical personnel to change or properly change and compose the equipment and the process flow described herein to realize the technology of the invention without departing from the content, the spirit and the scope of the invention. It is expressly intended that all such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and content of the invention.
Claims (7)
1. The efficient energy-saving ethyl lactate reaction rectification production device is characterized by consisting of a reaction rectification tower and a product refining tower or being independently realized by completely thermally coupling a reaction rectification tower with a bulkhead tower; the device comprises a reaction rectifying tower, a product refining tower, a lactic acid feed inlet, an ethanol feed outlet, a product refining tower, a product recovery tower, a product recycle tower and a product raw material lactic acid pipeline, wherein the lactic acid feed inlet is arranged at the top of the reaction section of the reaction rectifying tower, the ethanol feed inlet is arranged at the bottom of the reaction section of the.
2. The high-efficiency energy-saving ethyl lactate reaction rectification production device as claimed in claim 1, characterized in that the production device consists of two towers, namely a reaction rectification tower (3) and a product refining tower (17); the reactive distillation tower (3) consists of a distillation section (4), a reaction section (5) and a stripping section (6); the product refining tower (17) consists of a product refining tower rectifying section (18) and a product refining tower stripping section (19); the two-tower device comprises a reaction rectifying tower (3), a product refining tower (17), a tower top water condenser (8), a tower top ethyl lactate condenser (21), a tower bottom crude product reboiler (14), a tower bottom lactic acid reboiler (27), related feeding pipelines and pipelines for connecting the devices; a lactic acid (1) feeding pipeline is connected to the top of a reaction section (5) of a reaction rectifying tower (3), an ethanol (2) feeding pipeline is connected to the bottom of the reaction section (5) of the reaction rectifying tower (3), gas phase water (7) at the top of the reaction rectifying tower (3) is connected with a gas phase inlet of a tower top water condenser (8) through a pipeline, a condensed liquid phase water (9) material extraction pipeline is connected with a liquid phase outlet of the tower top water condenser (8), meanwhile, a part of reflux water (10) at the liquid phase outlet of the tower top water condenser (8) is connected with the top of the reaction rectifying tower (3) through a pipeline, and the other part of fractionated effluent (11) is extracted for removed light components; the bottom of the reaction rectifying tower (3) is connected with the inlet of a product refining tower (17) through a crude product extraction (16) pipeline, the steam at the top of the product refining tower (17) is connected with the gas inlet of a tower top ethyl lactate condenser (21) through a gas phase ethyl lactate (20) pipeline, after condensation, one part of reflux ethyl lactate (23) returns to the top of the product refining tower (17), the other part of high-purity ethyl lactate (24) is extracted from the top of the tower as a product, and one part of circulating lactic acid (29) material of the liquid phase product at the bottom of the product refining tower (17) is extracted and returned to the top of the reaction section (5) of the reaction rectifying tower (3).
3. The high-efficiency energy-saving ethyl lactate reaction rectification production device as claimed in claim 2, characterized in that the internals of the rectification section (4) and the stripping section (6) of the reaction rectification tower (3) are both packing or trays, and the internals of the reaction section (5) are regular loaded molecular sieve type catalytic separation internals or catalytic packing or a combination form thereof; the internals of the product refining tower (17) are all packing or trays.
4. The high-efficiency energy-saving ethyl lactate reaction rectification production device as claimed in claim 2, wherein the number of tower plates of the reaction rectification tower is 20-50, wherein the number of tower plates of the rectification section is 5-15, the number of tower plates of the reaction section is 10-40, and the number of tower plates of the stripping section is 2-15; the number of tower plates of the product refining tower is 10-20, wherein the number of tower plates of the rectifying section is 5-9, and the number of tower plates of the stripping section is 7-15.
5. The high-efficiency energy-saving ethyl lactate reaction rectification production device as claimed in claim 1, characterized in that the production device is realized by a reaction rectification complete thermal coupling bulkhead column (30) and the reaction rectification complete thermal coupling bulkhead column (30) consists of a main column rectification section (31), a main column reaction section (32), a main column stripping section (33), an auxiliary column rectification section (34) and an auxiliary column stripping section (35); comprises a reaction rectification fully thermally coupled dividing wall column (30), an overhead water condenser (8), an overhead ethyl lactate condenser (21), a tower bottom lactic acid reboiler (27), related feed pipelines and pipelines for connecting the above devices; a lactic acid (1) feeding pipeline is connected to the top of a main tower reaction section (32) of a reaction rectification complete thermal coupling bulkhead tower (30), an ethanol (2) feeding pipeline is connected to the bottom of the main tower reaction section (32) of the reaction rectification complete thermal coupling bulkhead tower (30), gas phase water (7) at the top of the main tower of the reaction rectification complete thermal coupling bulkhead tower (30) is connected with a gas phase inlet of a tower top water condenser (8) through a pipeline, a condensed liquid phase water (9) material extraction pipeline is connected with a liquid phase outlet of the tower top water condenser (8), meanwhile, a part of reflux water (10) at the liquid phase outlet of the tower top water condenser (8) is connected with the top of the main tower of the reaction rectification complete thermal coupling bulkhead tower (30) through a pipeline, and the other part of fractionated effluent (11) is discharged for removed light components; the gas phase ethyl lactate (20) at the top of the auxiliary tower of the reactive distillation complete thermal coupling partition tower (30) is connected with a gas phase inlet of an ethyl lactate condenser (21) at the top of the tower through a pipeline, a material extraction pipeline of liquid phase ethyl lactate (22) is connected with a liquid phase outlet of the ethyl lactate condenser (21) at the top of the tower, meanwhile, one part of reflux ethyl lactate (23) at the liquid phase outlet of the ethyl lactate condenser (21) at the top of the tower is connected with the top of the auxiliary tower of the reactive distillation complete thermal coupling partition tower (30) through a pipeline, and the other part of high-purity ethyl lactate (24) is taken as a; the liquid phase lactic acid (26) returned from the tower bottom of the reaction rectification complete thermal coupling partition wall tower (30) is connected with the liquid phase inlet of the tower bottom lactic acid reboiler (27) through a pipeline, meanwhile, the gas phase outlet of the tower bottom lactic acid reboiler (27) is also connected with the tower bottom of the reaction rectification complete thermal coupling partition wall tower (30) through a tower return gas phase lactic acid (28) pipeline, and the other part of circulating lactic acid (29) material is extracted as a raw material to be converged with the lactic acid (1) and then returned to the top of the main tower reaction section (32) of the reaction rectification complete thermal coupling partition wall tower (30).
6. The high-efficiency energy-saving ethyl lactate reaction rectification production device as claimed in claim 5, characterized in that a partition is arranged in the middle of a reaction rectification fully thermally coupled partition wall tower (30), the upper part of the partition wall tower is capped to divide a tower body into a main tower and an auxiliary tower, a reaction zone is positioned in the main tower, a product refining zone is positioned in the auxiliary tower, and the auxiliary tower needs two condensers which are an overhead water condenser (8), an overhead ethyl lactate condenser (21) and a tower bottom lactic acid reboiler (27); the internal parts of the main tower rectifying section (31), the main tower stripping section (33), the auxiliary tower rectifying section (34) and the auxiliary tower stripping section (35) are all packing or trays, and the internal parts of the main tower reaction section (32) are regular load molecular sieve type catalytic separation internal components or catalytic packing or a combination form of the regular load molecular sieve type catalytic separation internal components or the catalytic packing.
7. The high-efficiency energy-saving ethyl lactate reaction rectification production device as claimed in claim 5, wherein the total number of the tower plates of the reaction rectification complete thermal coupling bulkhead tower is 40-80, wherein the number of the tower plates of the rectification section of the main tower is 5-10, the number of the tower plates of the reaction section of the main tower is 10-40, the number of the tower plates of the stripping section of the main tower is 5-13, the number of the tower plates of the rectification section of the auxiliary tower is 10-20, and the number of the tower plates of the stripping section of the auxiliary tower is 10-15.
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| CN114712877A (en) * | 2022-04-15 | 2022-07-08 | 南京佳华工程技术有限公司 | Method and equipment for preparing electronic grade gas by adopting thermal coupling technology |
| CN114748884A (en) * | 2022-05-07 | 2022-07-15 | 天津大学 | Lactate reaction rectification apparatus for producing |
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| CN114712877A (en) * | 2022-04-15 | 2022-07-08 | 南京佳华工程技术有限公司 | Method and equipment for preparing electronic grade gas by adopting thermal coupling technology |
| CN114748884A (en) * | 2022-05-07 | 2022-07-15 | 天津大学 | Lactate reaction rectification apparatus for producing |
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