Device for producing L-lactide from L-lactic acid

Abstract

The utility model provides a device for producing L-lactide from L-lactic acid, which comprises a reaction kettle, a reactor and a gas tank, an atomizing nozzle is arranged on the inner wall of the reactor, the atomizing nozzle is communicated with the reaction kettle through a delivery pipe, and a melt pump is arranged in the middle of the delivery pipe; the device further comprises a distribution valve, the distribution valve is provided with an air inlet pipe and a first air outlet pipe, the air inlet pipe is communicated with the air tank, and the first air outlet pipe is communicated with the atomization nozzle. The device is convenient to operate and simple in structure, and can be inflated to clean the atomizing spray head after spraying materials, so that blockage is prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of lactide preparation equipment, in particular to a device for producing L-lactide from L-lactic acid. Background Art

[0002] As an important intermediate in the production of polylactic acid, the purity and specific rotation of lactide directly affect the quality and production cost of polylactic acid. According to different optical rotations, lactide can be divided into L-lactide, D-lactide, meso-lactide and racemic D, L-lactide, and the corresponding polylactic acid also has different optical isomers. Poly-L-lactic acid has the advantages of strong optical activity, regular segment arrangement, high crystallinity and mechanical strength, good biocompatibility, etc., and is widely used. Therefore, the improvement of L-lactide synthesis method and production equipment is of greater significance.

[0003] However, in the prior art, the melt pump needs to spray the L-lactide prepolymer through the atomizing nozzle. When not working, it is easy to cause blockage in the atomizing nozzle, which can easily delay the next production. In addition, the molten lactide in the reactor is relatively viscous, and only through automatic convergence, the convergence efficiency is slow, which is not conducive to the extraction of the melt pump. Utility Model Content

[0004] In order to solve the problems existing in the above-mentioned prior art, a device for producing L-lactide from L-lactic acid is provided to prevent the blockage of the nozzle and improve the extraction efficiency of the melt pump.

[0005] The technical solution adopted by the utility model to solve its technical problems is:

[0006] The utility model proposes a device for producing L-lactide from L-lactic acid, comprising a reaction kettle, a reactor and a gas tank, wherein an atomizing nozzle is arranged on the inner wall of the reactor, the atomizing nozzle is connected with the reaction kettle through a conveying pipe, a melt pump is arranged in the middle of the conveying pipe; and a distribution valve is also included, the distribution valve has an air inlet pipe and a first air outlet pipe, the air inlet pipe is connected with the gas tank, and the first air outlet pipe is connected with the atomizing nozzle.

[0007] Preferably, the air inlet pipe is connected to the gas tank through an air distribution pipe, the first air outlet pipe is connected to the atomizing nozzle through the delivery pipe, a baffle is slidably provided at the end of the first air outlet pipe, a piston block is fixed to the bottom of the baffle, and the piston block is fixed to the delivery pipe by an elastic component.

[0008] Preferably, a second air outlet pipe is also provided on one side of the distribution valve, and a plurality of fixed cylinders are fixed on the inner wall of the reactor, one of the fixed cylinders is connected to the second air outlet pipe through an air push pipe, and the fixed cylinders are connected to each other through pipelines, a sliding rod is sliding in the fixed cylinder, and a scraper is fixed at the bottom of the sliding rod; a block for opening and closing the second air outlet pipe is also fixed on the top of the baffle.

[0009] Preferably, the reactor comprises an inner wall and an outer shell, and a spiral heating device is provided between the inner wall and the outer shell.

[0010] Preferably, a water separator is fixed on one side of the reactor, the reactor and the water separator are connected through a pipeline, and a condenser is arranged in the water separator.

[0011] Preferably, the gas tank is connected to the reactor through a main gas pipe.

[0012] Preferably, a temperature controller is provided on the inner wall of the reactor.

[0013] Preferably, the elastic component comprises a spring cylinder fixed to the delivery tube, a telescopic rod slides inside the spring cylinder, one end of the telescopic rod is fixed to the piston block, and the other end of the telescopic rod is fixed to the spring cylinder via a spring.

[0014] Compared with the prior art, the beneficial effects of the utility model are:

[0015] 1. The utility model is provided with a distribution valve and an atomizing nozzle. After the atomizing nozzle sprays the material, the airflow distributed by the distribution valve can clean the atomizing nozzle to prevent blockage.

[0016] 2. The utility model is provided with a scraper, which can scrape the side wall material when extracting the material, and push the material downward to gather, thereby increasing the material flow speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0018] Figure 1 It is a three-dimensional diagram of the utility model;

[0019] Figure 2 It is a side schematic diagram of the utility model;

[0020] Figure 3 This is a cross-sectional view of the structure of the practical reactor;

[0021] Figure 4 It is a cross-sectional view of the practical distribution valve.

[0022] Description of reference numerals:

[0023] 1. Reactor; 2. Reactor; 3. Gas tank; 4. Atomizing nozzle; 5. Delivery pipe; 6. Gas distribution pipe; 7. Baffle; 8. Piston block; 9. Fixed cylinder; 10. Pushing pipe; 11. Sliding rod; 12. Scraper; 13. Block; 14. Melt pump; 15. Inner wall; 16. Outer shell; 17. Water distributor; 18. Temperature controller; 19. Telescopic rod; 20. Spring cylinder; 21. Heating device; 22. Condenser; 23. Main gas pipe; 24. Distribution valve; 241. Inlet pipe; 242. First outlet pipe; 243. Second outlet pipe. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0025] Embodiment 1

[0026] like Figure 1 , 2 As shown in Figure 4, this embodiment proposes an L-lactic acid production L-lactide device, which includes a reactor 1, a reactor 2 and a gas tank 3. The inner wall of the reactor 2 is provided with an atomizing nozzle 4, and the atomizing nozzle 4 can atomize the material and spray it onto the inner wall of the reactor 2 to accelerate the reaction speed of the material. The atomizing nozzle 4 is connected to the reactor 1 through a conveying pipe 5. A melt pump 14 is provided in the middle of the conveying pipe 5, which can realize that the material in the reactor 1 is conveyed to the atomizing nozzle 4 through the melt pump 14, and then sprayed into the reactor 2 through the atomizing nozzle 4.

[0027] It also includes a distribution valve 24, which has an air inlet pipe 241 and a first air outlet pipe 242. The air inlet pipe 241 is connected to the gas tank 3 through a pipeline, and the first air outlet pipe 242 is connected to the atomizing nozzle 4 through a pipeline. The distribution valve 24 can be used to distribute the airflow in the gas tank 3 to the atomizing nozzle 4 after the atomizing nozzle 4 has sprayed the material, so that the airflow can clean the atomizing nozzle 4 to prevent blockage.

[0028] The air inlet pipe 241 is connected with the gas tank 3 through the air distribution pipe 6, and the first air outlet pipe 242 is connected with the atomizing nozzle 4 through the delivery pipe 5. A baffle 7 is slidably arranged at the end of the first air outlet pipe 242, and the baffle 7 is in an "L" shape. A piston block 8 is fixed at the bottom of the baffle 7, and the piston block 8 is fixed to the delivery pipe 5 through an elastic component. When there is no material in the reactor 1, the melt pump 14 no longer conveys the material, and the piston block 8 is no longer pushed to the right by the material in the delivery pipe 5. At this time, the elastic component pulls the piston block 8 to move to the left, driving the baffle 7 to slide to the left, and the first air outlet pipe 242 will be connected with the delivery pipe 5. At this time, the airflow in the gas tank 3 passes through the air outlet pipe 242 and the delivery pipe 5 to blow and clean the atomizing nozzle 4.

[0029] The reactor 1 comprises an inner wall 15 and an outer shell 16 , a spiral heating device 21 is arranged between the inner wall 15 and the outer shell 16 , and can heat the material in the reactor 1 , and the outer shell 16 is made of heat-insulating material.

[0030] A water separator 17 is fixed on one side of the reactor 1. The reactor 1 and the water separator 17 are connected through a pipeline. A pipeline is fixed at the upper end and the lower end of the water separator 17 respectively. The water separator is connected to the reactor 1 through two pipelines. An opening that can be opened and closed freely is provided at the bottom of the water separator 17.

[0031] During the heating process, the steam in the reactor 1 enters the water separator 17 from the upper end pipeline, and is condensed by the condenser 22 in the water separator 17 to achieve stratification. The water is discharged through the opening at the bottom of the water separator 17, and the L-lactic acid flows back to the reactor 1 from the lower end pipeline.

[0032] A condenser 22 is disposed in the water separator 17 .

[0033] The gas tank 3 is connected to the reactor 2 through the main gas pipe 23 .

[0034] A temperature controller 18 is arranged on the inner wall of the reactor 2 .

[0035] The elastic component includes a spring cylinder 20 fixed to the delivery tube 5, a telescopic rod 19 slides inside the spring cylinder 20, one end of the telescopic rod 19 is fixed to the piston block 8, and the other end of the telescopic rod 19 is fixed to the spring cylinder 20 via a spring.

[0036] In this embodiment, the distribution valve 24 may also be replaced by a three-way valve in the prior art.

[0037] Embodiment 2

[0038] like Figure 3-4As shown, this embodiment proposes an L-lactic acid production L-lactide device, and other structures are the same as those of the first embodiment, except that, in this embodiment, a second air outlet pipe 243 is further provided on one side of the distribution valve 24, and a plurality of fixed cylinders 9 are fixed to the inner wall of the reactor 1, one of the fixed cylinders 9 is provided with an opening at the top, and an air push pipe 10 is fixedly connected to the opening, and the fixed cylinder 9 is connected to the second air outlet pipe 243 through the air push pipe 10, and the plurality of fixed cylinders 9 are interconnected through pipelines, and a sliding rod 11 slides in the fixed cylinder 9, and a scraper 12 is fixed to the bottom of the sliding rod 11, and the sliding rod 11 is driven to descend by inflating the air push pipe 10, so that the scraper 12 gathers the material downward.

[0039] A block 13 for opening and closing the second air outlet pipe 243 is also fixed on the top of the baffle 7. When there is material in the reactor 1, the melt pump 14 conveys the material, and the piston block 8 is pushed to the right by the material. The piston block 8 drives the baffle 7 to slide to the right, and the baffle 7 closes the passage between the air outlet pipe 242 and the conveying pipe 5; at the same time, it drives the block 13 to move to the right, and the second air outlet pipe 243 is connected with the air inlet pipe 241. At this time, the air inlet pipe 241 will pump air to the fixed cylinder 9 through the second air outlet pipe 243 and the air push pipe 10, and the sliding rod 11 in the gas fixed cylinder 9 drives the scraper 12 to move downward, scrapes the side wall material, and pushes the material downward to gather, thereby increasing the material flow rate.

[0040] Embodiment 3

[0041] like Figure 1-4 As shown, this embodiment proposes an L-lactic acid production L-lactide device, which includes a reactor 1, a reactor 2 and a gas tank 3. The inner wall of the reactor 2 is provided with an atomizing nozzle 4, and the atomizing nozzle 4 can atomize the material and spray it onto the inner wall of the reactor 2 to accelerate the reaction speed of the material. The atomizing nozzle 4 is connected to the reactor 1 through a conveying pipe 5. A melt pump 14 is provided in the middle of the conveying pipe 5, which can realize that the material in the reactor 1 is conveyed to the atomizing nozzle 4 through the melt pump 14, and then sprayed into the reactor 2 through the atomizing nozzle 4.

[0042] It also includes a distribution valve 24, which has an air inlet pipe 241 and a first air outlet pipe 242. The air inlet pipe 241 is connected to the gas tank 3 through a pipeline, and the first air outlet pipe 242 is connected to the atomizing nozzle 4 through a pipeline. The distribution valve 24 can be used to distribute the airflow in the gas tank 3 to the atomizing nozzle 4 after the atomizing nozzle 4 has sprayed the material, so that the airflow can clean the atomizing nozzle 4 to prevent blockage.

[0043] The air inlet pipe 241 is connected with the gas tank 3 through the air distribution pipe 6, and the first air outlet pipe 242 is connected with the atomizing nozzle 4 through the delivery pipe 5. A baffle 7 is slidably arranged at the end of the first air outlet pipe 242, and the baffle 7 is in an "L" shape. A piston block 8 is fixed at the bottom of the baffle 7, and the piston block 8 is fixed to the delivery pipe 5 through an elastic component. When there is no material in the reactor 1, the melt pump 14 no longer conveys the material, and the piston block 8 is no longer pushed to the right by the material in the delivery pipe 5. At this time, the elastic component pulls the piston block 8 to move to the left, driving the baffle 7 to slide to the left, and the first air outlet pipe 242 will be connected with the delivery pipe 5. At this time, the airflow in the gas tank 3 passes through the air outlet pipe 242 and the delivery pipe 5 to blow and clean the atomizing nozzle 4.

[0044] like Figure 3-4 As shown, this embodiment proposes an L-lactic acid production L-lactide device, and other structures are the same as those of the first embodiment, except that, in this embodiment, a second air outlet pipe 243 is further provided on one side of the distribution valve 24, and a plurality of fixed cylinders 9 are fixed to the inner wall of the reactor 1, one of the fixed cylinders 9 is provided with an opening at the top, and an air push pipe 10 is fixedly connected to the opening, and the fixed cylinder 9 is connected to the second air outlet pipe 243 through the air push pipe 10, and the plurality of fixed cylinders 9 are interconnected through pipelines, and a sliding rod 11 slides in the fixed cylinder 9, and a scraper 12 is fixed to the bottom of the sliding rod 11, and the sliding rod 11 is driven to descend by inflating the air push pipe 10, so that the scraper 12 gathers the material downward.

[0045] A block 13 for opening and closing the second air outlet pipe 243 is also fixed on the top of the baffle 7. When there is material in the reactor 1, the melt pump 14 conveys the material, and the piston block 8 is pushed to the right by the material. The piston block 8 drives the baffle 7 to slide to the right, and the baffle 7 closes the passage between the air outlet pipe 242 and the conveying pipe 5; at the same time, it drives the block 13 to move to the right, and the second air outlet pipe 243 is connected with the air inlet pipe 241. At this time, the air inlet pipe 241 will pump air to the fixed cylinder 9 through the second air outlet pipe 243 and the air push pipe 10, and the sliding rod 11 in the gas fixed cylinder 9 drives the scraper 12 to move downward, scrapes the side wall material, and pushes the material downward to gather, thereby increasing the material flow rate.

[0046] The reactor 1 comprises an inner wall 15 and an outer shell 16 , and a spiral heating device 21 is arranged between the inner wall 15 and the outer shell 16 .

[0047] The reactor 1 comprises an inner wall 15 and an outer shell 16 , a spiral heating device 21 is arranged between the inner wall 15 and the outer shell 16 , and can heat the material in the reactor 1 , and the outer shell 16 is made of heat-insulating material.

[0048] A water separator 17 is fixed on one side of the reactor 1. The reactor 1 and the water separator 17 are connected through a pipeline. A pipeline is fixed at the upper end and the lower end of the water separator 17 respectively. The water separator is connected to the reactor 1 through two pipelines. An opening that can be opened and closed freely is provided at the bottom of the water separator 17.

[0049] During the heating process, the steam in the reactor 1 enters the water separator 17 from the upper end pipeline, and is condensed by the condenser 22 in the water separator 17 to achieve stratification. The water is discharged through the opening at the bottom of the water separator 17, and the L-lactic acid flows back to the reactor 1 from the lower end pipeline.

[0050] The gas tank 3 is connected to the reactor 2 through the main gas pipe 23 .

[0051] A temperature controller 18 is arranged on the inner wall of the reactor 2 .

[0052] The elastic component includes a spring cylinder 20 fixed to the delivery tube 5, a telescopic rod 19 slides inside the spring cylinder 20, one end of the telescopic rod 19 is fixed to the piston block 8, and the other end of the telescopic rod 19 is fixed to the spring cylinder 20 via a spring.

[0053] Specific working process:

[0054] S1: Add L-lactic acid and catalyst zinc oxide to the reactor 1, raise the temperature to 90-100°C, and keep the temperature to concentrate for 2 hours. This step removes free water in the material.

[0055] S2: The temperature is raised to 110-140°C, and the mixture is concentrated at this temperature for 2 hours to remove bound water in the material and obtain a prepolymer of L-lactide. The steam during the heating process enters the water separator 17, and after being condensed by the condenser 22 in the water separator 17, stratification is achieved. The water is discharged through the opening at the bottom of the water separator 17, and the L-lactic acid flows back to the reactor.

[0056] S3: The L-lactide prepolymer in the reactor 1 is heated to 190-200° C. again, and the prepolymer is sent to the atomizing nozzle 4 by the melt pump 14 , and then the prepolymer is sprayed into the reactor 2 through the atomizing nozzle 4 .

[0057] S4: The gas tank 3 transports gas to the outside. After heating, protective gas with a temperature of 200-210°C is introduced into the reactor 2 through the main gas pipe 23. At the same time, hot water at 90°C is introduced into the temperature controller 18. The pressure of the reactor 2 is continuously maintained at normal pressure. After reacting for 2-3 hours, L-lactide is obtained.

[0058] In S1, the catalyst can be replaced by zinc lactate or a rare earth metal catalyst.

[0059] In S3, the material is conveyed normally, and there is material flowing through the conveying pipe 5. The piston block 8 will be pushed to the right by the material, driving the baffle 7 to close the passage between the first air outlet pipe 242 and the conveying pipe 5; at the same time, it drives the baffle 13 to move to the right, the second air outlet pipe 243 is opened, and the air inlet pipe 241 is connected with the air push pipe 10 and the fixed cylinder 9. At this time, the sliding rod 11 in the fixed cylinder 9 will drive the scraper 12 to move downward, scrape the side wall material, and push the material downward to gather, thereby increasing the material flow rate; after the material is conveyed, when there is no material flowing through the conveying pipe 5, the piston block 8 is no longer pushed to the right, and the piston block 8 will be pulled to the left by the elastic component, the baffle 7 is opened, and the first air outlet pipe 242 is connected with the conveying pipe 5. At this time, the gas in the first air outlet pipe 242 will blow and clean the atomizing nozzle 4 through the conveying pipe 5.

[0060] In S4, the protective gas can be helium, neon, argon, krypton, xenon, radon, gas.

[0061] The device has a simple structure and is easy to operate. It solves the problems of complicated preparation of L-lactide, too high depolymerization temperature of lactic acid oligomers, high system viscosity, severe oxidation, carbonization and coking of reactants, and reduces energy consumption, improves production efficiency, and further reduces the cost of polylactic acid.

[0062] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A device for producing L-lactide from L-lactic acid, comprising a reaction kettle (1), a reactor (2) and a gas tank (3), characterized in that: The inner wall of the reactor (2) is provided with an atomizing nozzle (4), and the atomizing nozzle (4) is connected to the reactor (1) via a delivery pipe (5), and a melt pump (14) is provided in the middle of the delivery pipe (5); it also includes a distribution valve (24), and the distribution valve (24) has an air inlet pipe (241) and a first air outlet pipe (242), the air inlet pipe (241) is connected to the gas tank (3), and the first air outlet pipe (242) is connected to the atomizing nozzle (4).

2. The device for producing L-lactide from L-lactic acid according to claim 1, characterized in that: The air inlet pipe (241) is connected to the gas tank (3) via an air distribution pipe (6); the first air outlet pipe (242) is connected to the atomizing nozzle (4) via the delivery pipe (5); a baffle (7) is slidably disposed at the end of the first air outlet pipe (242); a piston block (8) is fixed to the bottom of the baffle (7); and the piston block (8) is fixed to the delivery pipe (5) via an elastic component.

3. The device for producing L-lactide from L-lactic acid according to claim 2, characterized in that: A second air outlet pipe (243) is also provided on one side of the distribution valve (24); a plurality of fixed cylinders (9) are fixed on the inner wall of the reactor (1); one of the fixed cylinders (9) is connected to the second air outlet pipe (243) via an air push pipe (10); the fixed cylinders (9) are connected to each other via pipelines; a sliding rod (11) slides inside the fixed cylinder (9); a scraper (12) is fixed at the bottom of the sliding rod (11); a block (13) for opening and closing the second air outlet pipe (243) is also fixed on the top of the baffle (7).

4. The device for producing L-lactide from L-lactic acid according to claim 1, characterized in that: The reaction kettle (1) comprises an inner wall (15) and an outer shell (16), and a spiral heating device (21) is arranged between the inner wall (15) and the outer shell (16).

5. The device for producing L-lactide from L-lactic acid according to claim 4, characterized in that: A water separator (17) is fixed on one side of the reaction kettle (1); the reaction kettle (1) and the water separator (17) are connected via a pipeline; and a condenser (22) is arranged in the water separator (17).

6. The device for producing L-lactide from L-lactic acid according to claim 1, characterized in that: The gas tank (3) is connected to the reactor (2) via a main gas pipe (23).

7. The device for producing L-lactide from L-lactic acid according to claim 6, characterized in that: A temperature controller (18) is arranged on the inner wall of the reactor (2).

8. The device for producing L-lactide from L-lactic acid according to claim 2, characterized in that: The elastic component comprises a spring cylinder (20) fixed to the delivery pipe (5), a telescopic rod (19) sliding inside the spring cylinder (20), one end of the telescopic rod (19) being fixed to the piston block (8), and the other end of the telescopic rod (19) being fixed to the spring cylinder (20) via a spring.

Images