CN111943849A - High-efficiency and energy-saving ethyl lactate reactive distillation production method and device - Google Patents

Abstract

The invention relates to a high-efficiency and energy-saving reactive rectification production method and device for ethyl lactate, which is composed of a reactive rectification tower, a product refining tower or a reactive rectification complete thermal coupling tower, and lactic acid and ethanol enter the reactive rectification from the top and bottom of the reaction section. The tower and tower bottom materials enter the product refining tower, and the top of the product refining tower obtains high-purity ethyl lactate product. The lactic acid is recovered from the tower bottom and circulated to the reactive distillation tower, and the product water is discharged from the top of the reactive distillation tower. The invention realizes that the steady-state feed molar ratio of lactic acid and ethanol is 1:1, increases the molar ratio of lactic acid and ethanol through the reactive distillation reaction zone, promotes the complete conversion of ethanol, and avoids unreacted ethanol and product water. Azeotropic separation problem. The quality purity of the product reaches over 99%, and the yield reaches over 98%. The advantages of the invention are that the reactive distillation column and the product refining column are coupled and integrated by the method of complete thermal coupling, so as to further realize the substantial saving of production energy consumption and save the investment cost of equipment at the same time.

Description

High-efficiency and energy-saving ethyl lactate reactive distillation production method and device

technical field

The invention relates to the technical field of organic solvent ethyl lactate synthesis in the field of chemical industry, in particular to a high-efficiency and energy-saving reactive distillation production method and device of ethyl lactate; a method and device for producing ethyl lactate with high efficiency and energy saving by utilizing reactive distillation technology under the condition of lactic acid circulation. device.

Background technique

Solvents are widely used in almost all production and process industries. Commonly used solvents are mainly produced from non-renewable petroleum as raw materials, and the production process will release a large amount of carbon dioxide and volatile organic pollutants (VOCs). Chlorocarbon solvents, etc.) will play a vital role in reducing carbon/pollution emissions in my country.

Ethyl lactate, also known as ethyl α-hydroxypropionate, has a molecular formula of C ₅ H ₁₀ O ₃ , a melting point of 26°C and a boiling point of 154.5°C. It is a green and environmentally friendly solvent with good biodegradability and is widely used in fragrances. , solvents, lubricants, plasticizers and other different chemical fields. Ethyl lactate is a colorless and slightly odorous liquid. It naturally exists in pineapple, citrus, apple and other fruits. It has good solubility and is miscible with water. It is miscible with alcohol, aromatic hydrocarbons, esters, hydrocarbons and oils. According to the U.S. Department of Energy, more than 80% of conventional solvents (especially halogenated hydrocarbons) in the world will be replaced by ethyl lactate in the future. Due to the high energy consumption and high cost of its production method, its wide application in industry is limited. Therefore, it is urgent to develop an energy-saving, low-cost, green and environmentally friendly production method for ethyl lactate.

At present, the traditional production process of ethyl lactate mainly uses lactic acid and ethanol as raw materials, first generates ethyl lactate through catalytic reaction, and after the reaction is completed, ethyl lactate in the reaction product is purified by rectification or flash separation process and recycled reaction raw materials. This kind of traditional production has problems such as long process route and high investment cost. Therefore, reactive distillation processes are successively generated. The catalytic reaction and rectification separation are integrated in the same equipment to reduce the cost. However, this process is to improve the conversion of the reaction. The excess ethanol and water are used to form an azeotrope and extracted from the top of the tower to promote the forward progress of the reaction, and the remaining ethanol is rectified to realize the recycling of ethanol. The residual ethanol in this process leads to a long subsequent separation process, and the energy consumption for the separation of ethanol and water azeotrope is relatively high, and the yield of ethyl lactate is not high. The patents and literature reports about the ethyl lactate reaction process are as follows:

Patent CN100427453C proposes a new process for synthesizing ethyl lactate by catalytic rectification. Lactic acid and ethanol react in the catalytic section of a catalytic rectification tower equipped with a strong acid ion exchange resin catalyst to generate ethyl lactate, and the tower still liquid is removed by a flash column. Impurities give ethyl lactate product. The molar ratio of ethanol and lactic acid in the method is 3:1 to 5:1, and the temperature of the tower kettle reboiler is 80 to 90° C. Therefore, the tower kettle liquid still contains water and unreacted ethanol. The separation of ethyl lactate reduces the yield of subsequent separation products.

Patent CN1110698340A proposes a process method for producing ethyl lactate by utilizing the reactive distillation partition wall column technology. The whole tower is divided into seven regions, the whole column rectification section, the middle section feed side rectification section, the middle section feed side reaction section, The middle-stage feed-side stripping section, the middle-stage draw-side rectification section, the middle-stage draw-side stripping section and the tower still generate ethyl lactate and water in the middle-stage feed-side reaction section, and the middle-stage draw-side rectification section is completed. Separation of ethanol and esterification product water, the product is purified in two stripping sections of the feed side and the draw side, and the ethyl lactate product is obtained at the bottom of the column. The tower has many areas and complex design. The molar ratio of fresh ethanol and lactic acid is 1.05 to 1.3:1, and the energy consumption for the separation of ethanol and water azeotrope is high.

Patent CN109438228A proposes to use reaction-pervaporation membrane-distillation technology to reduce energy consumption and ensure product quality. Lactic acid and ethanol are esterified with concentrated H ₂ SO ₄ under stirring to synthesize ethyl lactate under heating and pressure. After the mixed steam of ethanol, water and a small amount of ethyl lactate is fractionated by the fractionation tower, the mixed steam of ethanol and water is input to the pervaporation membrane for water separation, and the separated ethanol steam is output to the pervaporation membrane to continue to participate in the reaction. After the esterification reaction is completed, sodium carbonate is added to neutralize concentrated H ₂ SO ₄ , the esterification liquid is cooled and then distilled under reduced pressure to obtain ethyl lactate product. The catalyst of the method is concentrated H ₂ SO ₄ , which is prone to side reactions, reduces product yield, produces more three wastes, is difficult to recycle, has complicated process flow, and high investment and operating costs.

Patent CN107032984A discloses a method for the continuous synthesis of ethyl lactate, which consists of two sections: reaction and separation. The molar ratio of ethanol and lactic acid is 2:1 to 4:1, which is fed into a fixed-bed reactor through a raw material pump for catalysis. The esterification reaction is carried out to obtain the crude ethyl lactate, which is then successively entered into the crude separation tower, the ethanol tower, the lactic acid tower and the ethyl lactate tower to obtain food-grade ethyl lactate. The method has long technological process, high equipment investment and operating costs, azeotrope between ethanol and water, and excessive ethanol leads to high energy consumption for recovery.

J.Gao,XMZhao,LYZhou,ZHHuang,Investigation of Ethyl LactateReactive Distillation Process,Chemical Engineering Research and Design,2007,85(4):525-529. Synthesis of ethyl lactate by catalytic reactive distillation technology, using ultrafine magnetic solid The super acid SO ₄ ^2- /ZrO ₂ -Fe ₃ O ₄ is used as the catalyst, and the feasibility of producing ethyl lactate by reactive distillation is confirmed by the method of simulation and experiment comparison. Water and ethanol are azeotroped from the tower The top is extracted, and the product ethyl lactate is obtained from the bottom of the tower. The yield of ethyl lactate is 82% higher than that of the simple esterification reactor, but the conversion rate of raw materials and product yield are still low.

In order to further reduce energy consumption, improve product yield, and reduce costs, it is of great significance to use high-efficiency and energy-saving reactive distillation of ethyl lactate to produce ethyl lactate to achieve energy saving by achieving a feed molar ratio of 1:1 and maximizing the use of reactants. .

SUMMARY OF THE INVENTION

The purpose of the present invention is to be suitable for the reactive distillation method and device for high-efficiency and energy-saving production of ethyl lactate, using the high-efficiency and energy-saving reactive distillation method provided by the present invention to produce ethyl lactate, with simple process flow, saving equipment investment cost, and convenient operation , the production energy consumption is low and the purity and reaction conversion rate of the target product ethyl lactate are very high.

The high-efficiency and energy-saving ethyl lactate reactive distillation production method and device of the present invention, wherein the lactic acid feed port is set at the top of the reaction section of the reactive distillation column, the ethanol feed port is set at the bottom of the reaction section of the reactive distillation column, and the product water It is discharged from the top of the reactive rectification tower, and the top of the product refining tower obtains a high-purity ethyl lactate product. The lactic acid is recovered from the tower kettle and recycled to the reactive rectification tower.

The method and device of the present invention are characterized in that the structure-activity relationship between the structure of the catalytic filler and the catalytic performance, the matching of the reaction and separation, the optimization of the number of theoretical plates and the residence time, the The feed molar ratio of lactic acid and ethanol is 2-4:1. Through the design of the reactive distillation process, the unreacted lactic acid and the product ethyl lactate are separated through the product refining process, so that the reactant lactic acid is recovered and recycled to the reactive distillation process. zone, and then increase the mol ratio of lactic acid and ethanol in the reaction zone, to realize that the steady state feed molar ratio of lactic acid and ethanol is completely reacted under the situation of 1:1, avoiding the azeotrope of unreacted ethanol and product water Separation puzzle. The reactive distillation tower and the product refining tower are further thermally coupled and integrated to achieve the purpose of energy saving.

The technology of the present invention is as follows:

The high-efficiency and energy-saving reactive rectification production method of ethyl lactate of the present invention is as follows: the production raw materials lactic acid and ethanol enter the reactive rectification zone from the top and bottom of the reaction section respectively, and carry out the esterification reaction in the catalytic separation internal components of the reactive rectification zone. At the same time, the product water and ethyl lactate are quickly removed from the reactive distillation zone, so that the reactant ethanol is completely converted; and the unreacted lactic acid and the product ethyl lactate are separated through the product refining process, so that the reactant lactic acid is recovered and recycled to the reactive distillation. ensure that the molar ratio of lactic acid and ethanol in the reactive distillation zone is at a high value; the final product water is discharged from the top of the reactive distillation column, and a high-purity ethyl lactate product is obtained at the top of the product refining unit column.

The operating process conditions of the high-efficiency energy-saving type ethyl lactate reactive distillation production method of the present invention are:

The operating pressure of the reactive distillation process is 40-101kPa; the reflux ratio of the reactive distillation process is 1-10.

The operating pressure of the product refining process is 100Pa～5kPa; the reflux ratio is 0.5～3.

The residence time of each theoretical grade of reaction material in the reaction zone is 20-70 seconds.

The catalyst loading amount on each theoretical plate in the reactive distillation zone is 0.1-0.6 cm ³ catalyst/cm ³ catalyst packing.

The initial feed molar ratio of lactic acid and ethanol is 2 to 4:1. When the process reaches a steady state, the unreacted lactic acid is circulated in the reactive distillation column to achieve a steady-state feed molar ratio of lactic acid and ethanol of 1:1. , the molar ratio of the reactant lactic acid to ethanol in the reactive distillation zone is 2-4:1.

The device for realizing the high-efficiency and energy-saving reactive rectification production method of ethyl lactate of the present invention can be composed of two towers, a reactive rectification tower and a product refining tower, or can be realized independently by one tower of a fully thermally coupled partition wall tower of reactive rectification.

The high-efficiency and energy-saving ethyl lactate reactive distillation production device of the present invention can be composed of two columns: a reactive distillation column (3) and a product refining column (17); the reactive distillation column (3) is composed of a reactive distillation column The distillation section (4), the reactive distillation column reaction section (5), and the reactive distillation column stripping section (6) are composed; the product purification column (17) is composed of the product purification column rectification section (18) and the product purification column stripping section Section (19) consists of. The two-column device comprises a reactive distillation column (3), a product refining column (17), a column top water condenser (8), a column top ethyl lactate condenser (21), a column bottom crude product reboiler (14), Column bottom lactic acid reboiler (27) and related feed lines and lines connecting the above equipment; fresh lactic acid (1) feed line is connected to the top of reactive distillation column (3) reaction section (5), ethanol (2) The feed line is connected to the bottom of the reactive distillation column (3) reaction section (5), and the reactive distillation column (3) overhead steam (7) is connected to the gas phase inlet of the overhead water condenser (8) through the pipeline, and the condensation The rear liquid phase water (9) material extraction pipeline is connected with the liquid phase outlet of the tower top water condenser (8), and a part of the liquid phase outlet of the tower top water condenser (8) is connected to the reactive distillation column (3) through the pipeline (10). ) the top of the tower is connected, and the other part (11) is the extraction of the light components removed; the reaction distillation tower (3) tower still and the product refining tower (17) inlet are connected by the crude product extraction (16) pipeline, and the product Refining tower (17) tower top steam is connected with tower top ethyl lactate condenser (21) gas phase inlet through pipeline (20), after condensation part (23) refluxes to product refining tower (17) tower top, another part (24 ) as a high-purity ethyl lactate product is extracted from the top of the tower, and a part (29) of the liquid phase product of the product refining tower (17) is extracted and returned to the top of the reaction section (5) of the reactive distillation column (3).

The reactive distillation column (3) is composed of a reactive distillation column rectification section (4), a reactive distillation column reaction section (5), and a reactive distillation column stripping section (6). The internal parts are all packings or trays, and the internal parts of the reaction section column are regular loaded molecular sieve type catalytic separation internals or catalytic packing or their combination; The stripping section (19) of the refining tower is composed, and the inner parts of the tower are all packings or trays. The number of trays in the reactive distillation column is 20 to 50, of which the number of trays in the rectifying section is 5 to 15, the number of trays in the reaction section is 10 to 40, and the number of trays in the stripping section is 2 to 15; the product The number of trays in the refining column is 10-20, of which the number of trays in the rectifying section is 5-9, and the number of trays in the stripping section is 7-15. The fully thermally coupled dividing wall column (30) of reactive rectification is divided into five areas, namely the main column rectification section (31), the main column reaction section (32), the main column stripping section (33), and the auxiliary column rectification section (34), auxiliary tower stripping section (35), a separator is set in the middle of the tower, and its upper part is capped, and the tower body is divided into a main tower and a auxiliary tower, the reaction zone is located in the main tower, and the product refining area is located in the auxiliary tower. Two condensers are required, namely an overhead water condenser (8), an overhead ethyl lactate condenser (21), and a bottom lactic acid reboiler (27).

The invention provides a high-efficiency and energy-saving ethyl lactate reactive rectification production device, wherein the production device is independently realized by one column of reactive rectification complete thermally coupled bulkhead tower (30), and reactive rectification complete thermally coupled bulkhead tower (30) is rectified by the main tower Section (31), main column reaction section (32), main column stripping section (33), auxiliary column rectification section (34) and auxiliary column stripping section (35) are composed. The one-column device includes a fully thermally coupled partition wall column (30) for reactive rectification, a column top water condenser (8), a column top ethyl lactate condenser (21), a column bottom lactic acid reboiler (27) and related feed pipelines And the pipeline that connects the above equipment; At the bottom of the thermally coupled bulkhead tower (30) reaction section (32), the reactive rectification is completely thermally coupled with the bulkhead tower (30) and the main tower top steam (7) is connected to the gas phase inlet of the top water condenser (8) through a pipeline, The material extraction line (9) is connected with the liquid phase outlet of the tower top water condenser (8), and a part of the liquid phase outlet of the tower top water condenser (8) is completely thermally coupled with the reactive rectification partition wall tower (30) through the pipeline (10). ) the top of the main tower is connected, and the other part (11) is the light component that is removed and is discharged; Reactive rectification is completely thermally coupled with the bulkhead tower (30) sub-column tower top gas-phase ethyl lactate (20) by pipeline and tower top lactic acid The ethyl ester condenser (21) gas phase inlet is connected, and the material extraction line (22) is connected with the liquid phase outlet of the tower top ethyl lactate condenser (21), and a part of the liquid phase outlet of the tower top ethyl lactate condenser (21) is simultaneously Through the pipeline (23), it is connected with the top of the auxiliary tower of the reactive rectification fully thermally coupled partition tower (30), and the other part (24) is extracted from the top of the tower as a high-purity ethyl lactate product; the reactive rectification fully thermally coupled partition tower (30) tower still liquid is connected with column bottom lactic acid reboiler (27) liquid phase inlet by pipeline (26), and simultaneously the column bottom lactic acid reboiler (27) gas phase outlet is also complete with reactive distillation through pipeline (28) The thermally coupled bulkhead tower (30) is connected to the bottom of the tower, and another part of the material (29) is extracted as a raw material to be combined with the fresh raw material (1) and then returned to the reaction section (32) of the fully thermally coupled bulkhead tower (30) for reactive distillation. the top of.

The fully thermally coupled dividing wall column (30) of reactive rectification is divided into five areas, namely the main column rectification section (31), the main column reaction section (32), the main column stripping section (33), and the auxiliary column rectification section (34), auxiliary tower stripping section (35), a separator is set in the middle of the tower, and its upper part is capped, and the tower body is divided into a main tower and a auxiliary tower, the reaction zone is located in the main tower, and the product refining area is located in the auxiliary tower. Two condensers are required, namely a column top water condenser (8), a column top ethyl lactate condenser (21), a column bottom lactic acid reboiler (27); the main column rectification section (31), the main column The inner parts of the stripping section (33), the rectification section of the auxiliary tower (34) and the stripping section of the auxiliary tower (35) are all packings or trays, and the inner parts of the reaction section (32) of the main tower are regular loaded molecular sieve catalysts. Separation internals or catalytic packing or combinations thereof; main column rectification section (31), main column stripping section (33), secondary column rectification section (34) and secondary column stripping section (35) column internals All are packings or trays, and the column internals of the reaction section (32) of the main tower are regular loaded molecular sieve type catalytic separation internals or catalytic packings or a combination thereof. The total number of plates in the fully thermally coupled dividing wall column of reactive rectification is 40 to 80, of which the number of plates in the rectification section of the main column is 5 to 10, the number of plates in the reaction section of the main column is 10 to 40, and the number of plates in the main column is stripped. The number of plates in the section is 5-13, the number of plates in the rectifying section of the auxiliary column is 10-20, and the number of plates in the stripping section of the auxiliary column is 10-15.

The high-efficiency and energy-saving ethyl lactate reactive distillation production device of the present invention 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 a production ethyl lactate pipeline, and the bottom A production circulating lactic acid pipeline is set up, 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 a high-efficiency and energy-saving reactive distillation technology. The lactic acid and ethanol enter the product refining unit after the reactive distillation process, so as to obtain a high-purity ethyl lactate product, and the lactic acid is extracted from the tower kettle and recycled to the reactive distillation unit. The advantage of the invention is that the quality purity of the product can reach more than 99%, and the yield can reach more than 98%. The reactive distillation column and the product refining column are coupled and integrated by the method of complete thermal coupling, so as to save more than 30% of production energy consumption and save equipment investment costs.

Description of drawings

Fig. 1 is the process flow schematic diagram of high-efficiency and energy-saving ethyl lactate reactive distillation production, which is composed of reactive distillation column (3) and product refining column (17).

Fig. 2 is a schematic diagram of a process flow for the production of high-efficiency and energy-saving reactive rectification of ethyl lactate, which is composed of a fully thermally coupled partition wall column (30) for reactive rectification.

Among them: 1-lactic acid; 2-ethanol; 3-reactive distillation column; 4-reactive distillation column rectification section; 5-reactive distillation column reaction section; 6-reactive distillation column stripping section; 7-gas phase water 8-top water condenser; 9-liquid phase water; 10-reflux water; 11-distillate water; 12-column bottom crude product; 13-return tower liquid phase crude product; 14-column bottom crude product reboiler ; 15-return tower gas phase crude product; 16- crude product extraction; 17- product refining tower; 18- product refining tower rectifying section; 19- product refining tower stripping section; 20- gas phase ethyl lactate; 21- tower Top ethyl lactate condenser; 22-liquid phase ethyl lactate; 23-reflux ethyl lactate; 24-high-purity ethyl lactate; 25-bottom liquid-phase lactic acid; 26-back-tower liquid-phase lactic acid; 27-bottom Lactic acid reboiler; 28-returning tower gas phase lactic acid; 29-circulating lactic acid; 30-reactive distillation complete thermally coupled dividing wall column; 31-main column rectification section; 32-main column reaction section; 33-main column stripping section 34-secondary column rectifying section; 35-secondary column stripping section.

Detailed ways

The method and device provided by the present invention will be further described below with reference to the accompanying drawings.

The present invention is achieved through the following technical solutions:

As shown in Figure 1, fresh lactic acid (1) is fed from the top of reaction section (5) in reactive distillation column (3), and fresh ethanol (2) is fed from reaction section (5) in reactive distillation column (3) The bottom feed, the liquid phase lactic acid and ethanol vapor entering the tower carry out esterification reaction in the reaction section (5), and the water generated enters the tower top water condensation from the reactive distillation tower (3) top gas phase outlet (7) The device (8) is condensed, and the condensed material flows out from the liquid phase outlet of the top water condenser (8), and a part of the liquid phase water (9) flows into the reactive distillation column (3) as the top reflux water (10), Another part of distillate water (11) is discharged as the light component that removes, and unreacted lactic acid and the ethyl lactate that generates are from reactive distillation column (3) tower still liquid phase outlet (12) a part (13) enters tower bottom thick. The product reboiler (14), another part is extracted (16) as a crude product, and the liquid phase material (16) extracted from the reaction distillation column (3) tower kettle enters the product refining column (17), and the product refining column ( 17) tower top gas phase product (20) flows out after the condensation of tower top ethyl lactate condenser (21), and a part of liquid phase ethyl lactate (22) returns product refining tower (17) as tower top reflux ethyl lactate (23) At the top of the tower, another part of high-purity ethyl lactate (24) is extracted as a product, and a part (26) of the liquid phase lactic acid (25) at the bottom of the tower returns to the bottom of the product refining tower (17) through the lactic acid reboiler (27) at the bottom of the tower, Another part of the material (29) is extracted as a raw material and returned to the top of the reaction section (5) of the reactive distillation column (3) after being combined with the fresh raw material (1).

As shown in Figure 2, fresh lactic acid (1) is completely thermally coupled to the top feed of the reaction section (32) in the bulkhead tower (30) by reactive rectification, and fresh ethanol (2) is completely thermally coupled to the bulkhead column (30) by reactive rectification. 30) in the bottom feed of reaction section (2), the liquid phase lactic acid and ethanol vapor entering the tower carry out esterification reaction in reaction section (2), and the water that generates is completely thermally coupled with bulkhead tower (30) from reactive distillation The gas phase outlet (7) at the top of the main tower enters the tower top water condenser (8) for condensation, and the condensed material flows out from the liquid phase outlet of the tower top water condenser (8), and a part of the liquid phase water (9) is used as the top of the tower. The reflux water (10) flows into the main tower of the reactive rectification complete thermally coupled bulkhead tower (30), and another part of the distillate water (11) is discharged as the light component removed; the product ethyl lactate is completely thermally coupled with the bulkhead tower (30) from the reactive rectification. 30) secondary tower tower top gas phase outlet (20) enters tower top ethyl lactate condenser (21) and is condensed, and the material after condensation flows out from tower top ethyl lactate condenser (21) liquid phase outlet, and liquid phase ethyl lactate condenser (21) flows out. A part of ester (22) flows into reactive rectification as the top reflux ethyl lactate (23) and is completely thermally coupled to the sub-column of bulkhead tower (30), and another part of high-purity ethyl lactate (24) is completely from reactive rectification as product ethyl lactate. The thermally coupled bulkhead tower (30) is extracted from the top of the auxiliary tower; the reactive rectification is completely thermally coupled with the bulkhead column (30), and a part of the liquid lactic acid (25) at the bottom of the column is returned to the reaction through a lactic acid reboiler (27) at the bottom of the column. The bottom of the rectification complete thermally coupled partition wall tower (30), and another part of the material (29) is extracted as a raw material and combined with the fresh raw material (1) and returned to the reaction section (32) of the fully thermally coupled partition wall tower (30) of the reactive rectification. top.

The operating process conditions of the high-efficiency and energy-saving ethyl lactate reactive rectification production method of the present invention are as follows: the operating pressure of the reactive rectification process is 40-101 kPa; the reflux ratio of the reactive rectification process is 1-10. The operating pressure of the product refining process is 100Pa～5kPa; the reflux ratio is 0.5～3. The residence time of each theoretical grade of reaction material in the reaction zone is 20-70 seconds. In the reactive distillation zone, the molar ratio of the reactant lactic acid to ethanol is 2-4:1.

If the device consists of two columns, the reactive distillation column (3) and the product refining column (17), the reactive distillation column (3) is composed of the reactive distillation column rectifying section (4) and the reactive distillation column reaction section (5) and a reactive distillation column stripping section (6); the product refining column (17) is composed of a product refining column rectifying section (18) and a product refining column stripping section (19). The two-column device comprises a reactive distillation column (3), a product refining column (21), a column top water condenser (8), a column top ethyl lactate condenser (25), a column bottom crude product reboiler (14), Column bottom lactic acid reboiler (27) and related feed lines and lines connecting the above equipment; fresh lactic acid (1) feed line is connected to the top of reactive distillation column (3) reaction section (5), ethanol (2) The feed line is connected to the bottom of the reactive distillation column (3) reaction section (5), and the reactive distillation column (3) top gas phase water (7) is connected with the top water condenser (8) gas phase inlet by pipeline, The liquid-phase water (9) material pipeline is connected with the liquid-phase outlet of the overhead water condenser (8), and a part of the liquid-phase outlet of the overhead water condenser (8) is connected to the top of the reactive distillation column (3) through the pipeline (10). Connected, another part (11) is produced for the removed light components. The inlet of the reactive distillation column (3) is connected with the inlet of the product refining column (17) through the crude product extraction (16) pipeline, and the top steam of the product refining column (17) is connected with the column top ethyl lactate condenser through the pipeline (20) (21) gas-phase inlets are connected, and after condensation, a part (23) is refluxed to the top of the product refining tower (17), and another part (24) is extracted from the top of the tower as a high-purity ethyl lactate product, and the product refining tower (17) tower A part (29) of the liquid phase product of the kettle is recovered and returned to the top of the reaction section (5) of the reactive distillation column (3).

If the device is realized by a separate column of reactive rectification complete thermally coupled bulkhead tower (30), reactive rectification complete thermally coupled bulkhead tower (30) consists of a main column rectification section (31), a main column reaction section (32), a main column The stripping section (33), the auxiliary column rectification section (34) and the auxiliary column stripping section (35) are composed. The one-column device includes a fully thermally coupled partition wall column (30) for reactive rectification, a column top water condenser (8), a column top ethyl lactate condenser (25), a column bottom lactic acid reboiler (27) and related feed pipelines And the pipeline that connects the above equipment; At the bottom of the reaction section (32) of the thermally coupled bulkhead tower (30), the reactive distillation is completely thermally coupled with the bulkhead tower (30), and the gas phase water (7) at the top of the main tower is connected to the gas phase inlet of the top water condenser (8) through a pipeline. , the liquid phase water (9) material pipeline is connected with the liquid phase outlet of the tower top water condenser (8), and at the same time a part of the liquid phase outlet of the tower top water condenser (8) is completely thermally coupled with the reactive distillation column through the pipeline (10) (30) The tops of the main towers are connected, and the other part (11) is discharged for the removed light components. Reactive rectification is completely thermally coupled to the sub-column tower top gas phase ethyl lactate (20) of the tower top ethyl lactate condenser (21) is connected with the gas phase inlet of the tower top ethyl lactate condenser (21), and the liquid phase ethyl lactate (22) material pipeline Be connected with tower top ethyl lactate condenser (21) liquid-phase outlet simultaneously, and tower top ethyl lactate condenser (21) liquid-phase outlet is partially through pipeline (23) and fully thermally coupled partition tower (30) auxiliary tower with reactive distillation The tops of the towers are connected, and another part (24) is withdrawn from the top of the towers as a high-purity ethyl lactate product. Reactive rectification complete thermally coupled bulkhead tower (30) tower bottom liquid is connected with column bottom lactic acid reboiler (27) liquid phase inlet through pipeline (26), and tower bottom lactic acid reboiler (27) gas phase outlet also passes through pipeline simultaneously (28) is connected with the bottom of the reactive rectification fully thermally coupled bulkhead tower (30), and another part of the material (29) is extracted as a raw material and returned to the reactive rectification fully thermally coupled bulkhead tower after being combined with fresh raw material (1). (30) Top of reaction section (32).

The high-efficiency and energy-saving ethyl lactate reactive distillation production device of the present invention 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 a production ethyl lactate pipeline, and the bottom A production circulating lactic acid pipeline is set up, and the circulating lactic acid pipeline is connected with the production raw material lactic acid pipeline.

Wherein, as shown in Figure 1, applied in Examples 1 and 2, the reactive distillation column (3) consists of the reactive distillation column rectifying section (4), the reactive distillation column reaction section (5), the reactive distillation column The distillation section (6) is composed of the column internals of the rectification section and the stripping section are packings or trays, and the column internals of the reaction section are regular loaded molecular sieve type catalytic separation internals or catalytic packings or their combined forms; product refining column (17) is composed of a rectifying section (18) of a product refining tower and a stripping section (19) of a product refining tower, and the inner parts of the tower are all packings or trays. The number of trays in the reactive distillation column is 20 to 50, of which the number of trays in the rectifying section is 5 to 15, the number of trays in the reaction section is 10 to 40, and the number of trays in the stripping section is 2 to 15; the product The number of trays in the refining column is 10-20, of which the number of trays in the rectifying section is 5-9, and the number of trays in the stripping section is 7-15. Or as shown in Figure 2, be applied in embodiment 3 and 4, reactive distillation complete thermally coupled bulkhead tower (30) is divided into five regions, respectively main tower rectifying section (31), main tower reaction section (32). ), the main column stripping section (33), the auxiliary column rectification section (34), the auxiliary column stripping section (35), a separator is arranged in the middle of the column, the upper part is capped, and the column body is divided into the main column and the auxiliary column. , the reaction zone is located in the main tower, the product refining area is located in the auxiliary tower, and the tower needs two condensers, namely the tower top water condenser (8), the tower top ethyl lactate condenser (21), a tower bottom lactic acid reboiler device (27). The main column rectification section (31), the main column stripping section (33), the auxiliary column rectification section (34) and the auxiliary column stripping section (35) are all packings or trays, and the main column reaction section ( 32) The column internals are regular supported molecular sieve type catalytic separation internals or catalytic packing or their combination. The total number of plates in the fully thermally coupled dividing wall column of reactive rectification is 40 to 80, of which the number of plates in the rectification section of the main column is 5 to 10, the number of plates in the reaction section of the main column is 10 to 40, and the number of plates in the main column is stripped. The number of plates in the section is 5 to 13, the number of plates in the rectifying section of the auxiliary column is 10 to 20, and the number of plates in the stripping section of the auxiliary column is 10 to 15. The catalyst loading amount on each theoretical plate in the reactive distillation zone is 0.1-0.6 cm ³ catalyst/cm ³ catalyst packing.

The technology and equipment of the present invention are widely used in the process of preparing ethyl lactate by esterification of lactic acid and ethanol. Four application examples are selected for illustration, but this does not limit the scope of application of this technology and equipment.

Example 1

The method of the present invention is used for the process of producing ethyl lactate by esterification of lactic acid and ethanol, which is the same as the process described in the present invention, including a reactive distillation column, a product refining column, a column top water condenser, a column top ethyl lactate condenser, The thick product reboiler at the bottom of the tower, the lactic acid reboiler at the tower bottom, wherein the operating pressure of the reactive distillation column is 101kPa, the reflux ratio is 9, and the fresh lactic acid feed amount is 50kmol/h, and the reaction mole of biomass-based lactic acid and ethanol The ratio is 2, the catalyst loading is 0.1 cm ³ catalyst/cm ³ catalytic packing, the operating pressure of the product purification tower is 5 kPa, and the reflux ratio is 0.5.

After the above process, the purity of the main product ethyl lactate can reach 99%, and the yield can reach 98.2%. Compared with the conventional reactive distillation process, the energy consumption can be reduced by more than 30%.

Example 2

The method of the present invention is used for the process of producing ethyl lactate by esterification of lactic acid and ethanol, which is the same as the process described in the present invention, including a reactive distillation column, a product refining column, a column top water condenser, a column top ethyl lactate condenser, The thick product reboiler at the bottom of the tower, the lactic acid reboiler at the tower bottom, wherein the operating pressure of the reactive distillation column is 40kPa, the reflux ratio is 10, and the fresh lactic acid feed amount is 15kmol/h, and the reaction mole of biomass-based lactic acid and ethanol The ratio is 3, the catalyst loading is 0.1cm ³ catalyst/cm ³ catalyst packing, the operating pressure of the product purification tower is 100pa, and the reflux ratio is 1.

After the above process, the purity of the main product ethyl lactate can reach 99.2%, the yield can reach 98.3%, and the energy consumption can be reduced by more than 30% compared with the conventional reactive distillation process.

Example 3

The method of the present invention is used for the process of producing ethyl lactate by esterification of lactic acid and ethanol, which is the same as the process described in the present invention, and includes reactive distillation complete thermally coupled partition tower, column top water condenser, column top ethyl lactate condenser, The lactic acid reboiler at the bottom of the column, wherein the operating pressure of the fully thermally coupled bulkhead column of reactive rectification is 50kPa, the reflux ratio of the main column is 2, the reflux ratio of the auxiliary column is 3, the feed amount of fresh lactic acid is 30kmol/h, and the biomass-based lactic acid is The reaction molar ratio to ethanol was 4, and the catalyst loading was 0.1 cm ³ catalyst/cm ³ catalyst packing.

After the above process, the purity of the main product ethyl lactate can reach 99.7%, and the yield can reach 98.6%. Compared with the conventional reactive distillation process, the energy consumption can be reduced by more than 40%.

Example 4

The method of the present invention is used for the process of producing ethyl lactate by esterification of lactic acid and ethanol, which is the same as the process described in the present invention, and includes reactive distillation complete thermally coupled partition tower, column top water condenser, column top ethyl lactate condenser, The lactic acid reboiler at the bottom of the column, wherein the operating pressure of the fully thermally coupled partition wall column for reactive rectification is 40kPa, the reflux ratio of the main column is 1.5, the reflux ratio of the auxiliary column is 2.5, the feed amount of fresh lactic acid is 15kmol/h, and the biomass-based lactic acid is The reaction molar ratio with ethanol was 3, and the catalyst loading was 0.1 cm ³ catalyst/cm ³ catalyst packing.

After the above process, the purity of the main product ethyl lactate can reach 99.3%, and the yield can reach 98.2%. Compared with the conventional reactive distillation process, the energy consumption can be reduced by more than 30%.

The high-efficiency and energy-saving reactive rectification production method and device for ethyl lactate proposed by the present invention have been described through preferred embodiments, and those skilled in the art can obviously perform the equipment described herein without departing from the content, spirit and scope of the present invention. The technology of the present invention can be realized by modifying or appropriately changing and forming the technological process. It should be particularly pointed out that all similar substitutions and modifications apparent to those skilled in the art are deemed to be included in the spirit, scope and content of the present invention.

Claims (10)

1. high-efficiency and energy-saving type ethyl lactate reactive distillation production method; it is characterized in that, raw material lactic acid and ethanol enter the reactive distillation zone from the top and bottom of the reaction section respectively, and when the catalysis of the reactive distillation zone carries out the esterification reaction, The product water and ethyl lactate are removed from the reactive distillation zone, so that the reactant ethanol is completely converted; and the unreacted lactic acid and the product ethyl lactate are separated through the product refining process, so that the reactant lactic acid is recovered and recycled to the reactive distillation zone to ensure the reaction The molar ratio of lactic acid and ethanol in the rectification zone is at a high value; the final product water is discharged from the top of the reactive distillation column, and a high-purity ethyl lactate product is obtained at the top of the product refining unit column. 2. method as claimed in claim 1 is characterized in that, the operating pressure of reactive distillation process is 40～101kPa; The reflux ratio of reactive distillation process is 1～10; Product refining process operating pressure is 100Pa～5kPa; The ratio is 0.5 to 3. 3. method as claimed in claim 1 is characterized in that, the reaction material residence time of every theoretical stage of reaction zone is 20～70 seconds; The catalyst loading on each theoretical plate of reaction rectification zone is 0.1～0.6cm ³ catalyst/cm ³ catalytic packing. 4. method as claimed in claim 1, is characterized in that, the feed molar ratio of initial lactic acid and ethanol is 2～4:1, treats that process reaches steady state, unreacted lactic acid is completely circulated in reactive distillation column, The steady-state feed molar ratio of lactic acid and ethanol is 1:1, and the molar ratio of reactant lactic acid to ethanol in the reactive distillation zone is 2-4:1. 5. high-efficiency and energy-saving type ethyl lactate reactive distillation production unit, is characterized in that, production unit is made up of two towers of reactive distillation column (3) and product refining tower (17); reactive distillation column (3) is made up of reactive distillation column (3) The column rectification section (4), the reactive rectification column reaction section (5), and the reactive rectification column stripping section (6) are composed; the product purification column (17) is composed of the product purification column rectification section (18) and the product purification column The stripping section (19) is composed; the two-column device comprises a reactive distillation column (3), a product refining column (17), a column top water condenser (8), a column top ethyl lactate condenser (21), a column bottom thick Product reboiler (14), bottom lactic acid reboiler (27) and related feed lines and lines connecting the above equipment; fresh lactic acid (1) feed line is connected to reactive distillation column (3) reaction section (5) ), the ethanol (2) feed line is connected to the bottom of the reactive distillation column (3) reaction section (5), and the reactive distillation column (3) overhead steam (7) passes through the pipeline and the overhead water condenser ( 8) The gas phase inlet is connected, and the liquid phase water (9) material extraction pipeline is connected with the liquid phase outlet of the tower top water condenser (8) after condensation, and a part of the liquid phase outlet of the tower top water condenser (8) passes through the pipeline (10). ) is connected with the top of reactive distillation column (3), and the other part (11) is extracted for the light components of removal; reactive distillation column (3) tower still and product refining tower (17) import are collected through crude product. Out (16) pipeline connection, product refining tower (17) tower top steam is connected with tower top ethyl lactate condenser (21) gas phase inlet by pipeline (20), and a part (23) after condensation is returned to product refining tower (17) ) top of the tower, another part (24) is extracted from the top of the tower as a high-purity ethyl lactate product, and a part of (29) material of the product refining tower (17) tower kettle liquid phase product is extracted and returned to the reactive distillation column (3) to react top of paragraph (5). 6. device as claimed in claim 5 is characterized in that, reactive distillation column (3) is by reactive distillation column rectifying section (4), reactive distillation column reaction section (5), reactive distillation column stripping Section (6) is composed, the column internals of the rectification section and the stripping section are packings or trays, and the column internals of the reaction section are regular loaded molecular sieve type catalytic separation internals or catalytic packing or their combination; 17) It consists of a rectifying section (18) of a product refining tower and a stripping section (19) of a product refining tower, and the inner parts of the tower are all packings or trays. 7. The device according to claim 5, wherein the number of plates in the reactive distillation column is 20 to 50, wherein the number of plates in the rectifying section is 5 to 15, and the number of plates in the reaction section is 10 to 40 The number of trays in the stripping section is 2 to 15; the number of trays in the product refining column is 10 to 20, of which the number of trays in the rectification section is 5 to 9, and the number of trays in the stripping section is 7 to 15. . 8. High-efficiency and energy-saving type ethyl lactate reactive distillation production unit, it is characterized in that, the production unit is realized separately by one tower of reactive rectification complete thermally coupled next-door tower (30), and reactive rectification complete thermally coupled next-to-wall tower (30) by the main The column rectification section (31), the main column reaction section (32), the main column stripping section (33), the auxiliary column rectification section (34) and the auxiliary column stripping section (35) are composed; Coupling partition wall column (30) and column top water condenser (8), column top ethyl lactate condenser (21), column bottom lactic acid reboiler (27) and relevant feed pipeline and the pipeline that connects above equipment; Fresh lactic acid (1) the feed line is connected to the top of the reaction section (32) of the reactive rectification complete thermally coupled bulkhead tower (30), and the fresh ethanol (2) feed line is connected to the reactive rectification complete thermally coupled bulkhead tower (30) reaction section At the bottom of (32), reactive distillation is completely thermally coupled to the bulkhead tower (30), and the main tower top steam (7) is connected to the gas phase inlet of the tower top water condenser (8) through a pipeline, and the material extraction pipeline (9) is connected to the tower top steam (7). The liquid phase outlet of the overhead water condenser (8) is connected, and at the same time, a part of the liquid phase outlet of the overhead water condenser (8) is connected to the top of the main tower tower of the reactive distillation complete thermally coupled partition tower (30) through the pipeline (10). A part (11) is the light component that is removed and is discharged; Reactive rectification completely thermally couples bulkhead tower (30) sub-column top gas phase ethyl lactate (20) through pipeline and tower top ethyl lactate condenser (21) gas phase inlet Connected, the material extraction line (22) is connected with the liquid phase outlet of the ethyl lactate condenser (21) at the top of the tower, and a part of the liquid phase outlet of the ethyl lactate condenser (21) at the top of the tower is connected with the reactive distillation through the pipeline (23). Completely thermally coupled bulkhead tower (30) and the top of the auxiliary tower are connected, and the other part (24) is extracted from the top of the tower as a high-purity ethyl lactate product; the reaction rectification is completely thermally coupled with the bulkhead tower (30) column kettle liquid through the pipeline ( 26) be connected with the column bottom lactic acid reboiler (27) liquid phase inlet, and the column bottom lactic acid reboiler (27) gas phase outlet is also through pipeline (28) and the reactive distillation complete thermal coupling at the bottom of the tower (30) Connected, another part of the material (29) is taken out as a raw material to be combined with the fresh raw material (1) and returned to the top of the reaction section (32) of the reaction rectification complete thermally coupled partition wall column (30). 9. device as claimed in claim 8, is characterized in that, reactive distillation complete thermal coupling bulkhead tower (30) is divided into five regions, respectively main tower rectifying section (31), main tower reaction section (32) , the main tower stripping section (33), the auxiliary tower rectification section (34), the auxiliary tower stripping section (35), a separator is set in the middle of the tower, the upper part is capped, and the tower body is divided into the main tower and the auxiliary tower, The reaction zone is located in the main tower, and the product refining zone is located in the auxiliary tower. This tower requires two condensers, namely the tower top water condenser (8), the tower top ethyl lactate condenser (21), and a tower bottom lactic acid reboiler. (27); The main column rectification section (31), the main column stripping section (33), the auxiliary column rectification section (34) and the auxiliary column stripping section (35) are all packings or trays. The column internals of the column reaction section (32) are regular supported molecular sieve type catalytic separation internals or catalytic packing or their combination. 10. The device according to claim 8, characterized in that, the total number of plates in the fully thermally coupled partition wall column of reactive rectification is 40 to 80, wherein the number of plates in the rectifying section of the main column is 5 to 10, and the number of plates in the main column is 5 to 10. The number of plates in the reaction section is 10 to 40, the number of plates in the stripping section of the main column is 5 to 13, the number of plates in the rectification section of the auxiliary column is 10 to 20, and the number of plates in the stripping section of the auxiliary column is 10 to 13. 15 bucks.

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