Industrial device for producing glycolide product

Abstract

The utility model relates to an industrial device for producing glycolide products, which comprises a reaction kettle with a jacket type structure, a feeding pipeline is connected to the inside of the reaction kettle, the top of the reaction kettle is connected with a primary condenser through a pipeline, and a gas outlet of the primary condenser is connected with a secondary condenser through a pipeline. A gas outlet of the second-stage condenser is subjected to tail gas vacuumizing; liquid outlets of the first-stage condenser and the second-stage condenser are connected to the top of the settling tank in parallel through pipelines, a sediment pipeline is arranged at the bottom of the settling tank and connected into the reaction kettle, and a product outlet is further formed in the bottom of the settling tank; a motor is arranged at the top of the reaction kettle and drives a stirring rod, and a stirring paddle is arranged at the bottom of the stirring rod. The device has the beneficial effects that reaction residues and wall hanging phenomena are reduced, the reaction rate is accelerated, and the yield of glycolide products can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of preparation of degradable biomaterial monomers, in particular to an industrial device for producing glycolide products. Background Art

[0002] Glycolide is a white powdery solid with flaky crystals. Glycolide easily reacts with water to form glycolic acid and linear dimers of glycolic acid. Through ring-opening coordination polymerization, glycolide can be homopolymerized to obtain high molecular weight polyglycolide (PGA), or copolymerized with lactide to prepare polyglycolide-lactide copolymer (PGLA). This type of polymer is a kind of burden-free biodegradable material. The final degradation products are water and carbon dioxide, and it has good biocompatibility. It has been widely used in high value-added products such as absorbable surgical sutures, simulated human tissue materials, as well as packaging materials and agricultural biodegradable films. There are currently two main methods for synthesizing glycolide. One is to prepare glycolide using chloroacetic acid as raw material. This method has been eliminated due to the problems that are difficult to solve, such as high toxicity of raw materials, severe corrosion of equipment, and residual toxicity of products; the other is to prepare glycolide using glycolic acid as raw material. This method is the mainstream method for preparing glycolide, but it also has many problems that need to be solved. U.S. Patent No. 2,668,162 discloses a method in which glycolic acid oligomers are crushed into powder and heated under ultra-high vacuum for depolymerization, and glycolide vapor is collected. This method makes the oligomers heavy when heated, so a large amount of residue is left in the reactor, resulting in a decrease in glycolide production, and the residue must be removed. U.S. Patent No. 4,727,163 shows a method for producing glycolide, in which a polyether with good thermal stability is used as a substrate, and then a small amount of glycolic acid is block copolymerized with the substrate to obtain a block copolymer, and the block copolymer is finally heated for depolymerization. However, the generation of the block copolymer is difficult to control and increases production costs. In addition, the by-products produced by this method will cause pipeline blockage and other problems when separated in the recovery pipeline. The above-mentioned problems are that the heat and mass transfer of materials in the preparation process of glycolide and the separation and treatment of by-products in the reaction system are not well solved, resulting in a large amount of residue generated during the reaction process, resulting in low product yield, serious equipment pipeline blockage, high energy consumption and high cost. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the purpose of the utility model is to provide an industrialized device for producing glycolide products, aiming to solve the problems of large amount of reaction residues, low product yield, high energy consumption and high cost in the current glycolide production process. To achieve the above-mentioned purpose, the technical scheme adopted by the utility model is as follows: the reactor is a jacketed structure, the feed pipeline is connected to the inside of the reactor, the top of the reactor is connected to the primary condenser through a pipeline, the gas outlet of the primary condenser is connected to the secondary condenser through a pipeline, and the gas outlet of the secondary condenser is vacuumized for tail gas; the liquid outlets of the primary condenser and the secondary condenser are connected to the top of the sedimentation tank in parallel through a pipeline, the bottom of the sedimentation tank is provided with a sediment pipeline connected to the reactor, and the bottom of the sedimentation tank is also provided with a product outlet; a motor is provided at the top of the reactor, the motor drives a stirring rod, and a stirring paddle is provided at the bottom of the stirring rod.

[0004] The lower part of the shell side of the reactor is provided with a steam inlet, and the upper part of the shell side of the reactor is provided with a steam outlet.

[0005] A cooling liquid bypass pipe is inserted from the outside into the bottom of the reactor. The cooling liquid bypass pipe is a spiral rising structure in the reactor and extends from the upper part of the reactor. The low-temperature freezing liquid is a sodium chloride brine-ethylene glycol mixture, which has a good cooling effect and a fast temperature reduction. It can better adjust the reaction temperature and prevent overheating.

[0006] A plurality of heating rods are arranged on the stirring rod, the heating rods in the same row are perpendicular to each other, and the heating rods in the same column are parallel to each other. The electric heating method can provide heat to the material quickly, thereby improving efficiency.

[0007] The distance between the bottommost heating rod and the stirring paddle is 0.2-5.0 cm.

[0008] The distance between the blade of the stirring paddle and the bottom of the reactor is 0.1-3.0 cm, and the distance between the blade of the stirring paddle and the inner wall of the reactor is 0.1-5.0 cm.

[0009] A water phase outlet is arranged on the side wall of the sedimentation tank, and the water phase outlet is an overflow weir with adjustable height, and the adjustable range of the overflow weir is 5.0 to 50.0 cm from the bottom of the sedimentation tank.

[0010] A pressure balance pipe is arranged on the top of the side wall of the sedimentation tank and is connected to the gas phase outlet of the secondary condenser.

[0011] As a preferred solution, the inner wall of the reactor body is provided with a high temperature resistant and anti-material adhesion coating, and the coating material is one of polytetrafluoroethylene, polystyrene, tungsten carbide and ceramic.

[0012] As a preferred solution, the motor, heating rod and stirring paddle are made of metal materials with high strength, high temperature resistance and good heat conduction, and the metal material is one of 316L stainless steel, molybdenum steel, Hastelloy alloy and copper-zinc alloy.

[0013] As a preferred solution, the blade type of the stirring paddle is frame type, anchor type or spiral ribbon type, which can play a good role in scraping the wall. Combined with the anti-sticking coating of the kettle body, it can greatly prevent the material from hanging on the wall during the reaction process.

[0014] As a preferred embodiment, the primary condenser and the secondary condenser are one of a stainless steel shell and tube condenser, a horizontal graphite condenser, and a silicon carbide condenser. The refrigerant medium of the primary condenser adopts boiler circulating water to save resources. The temperature of the boiler circulating water is controlled at 80-90°C. The cooling temperature can ensure that glycolide is condensed into liquid without solidifying and clogging pipeline equipment; the refrigerant medium of the secondary condenser adopts a low-temperature refrigerant, which is a sodium chloride brine-ethylene glycol mixture. It has a good cooling effect and can completely condense the water and low-boiling intermediates generated during the reaction process, thereby reducing system material losses.

[0015] Beneficial effects of the utility model:

[0016] The anti-stick coating on the kettle body can greatly reduce the adhesion of reaction raw materials and products to the wall and reduce reaction residues; the heating rod can assist in heating the materials with slower heat transfer in the middle of the reactor, increase the heat transfer efficiency and thus accelerate the reaction rate; secondly, it can make the unevenly stirred materials in the middle of the reactor mix more fully and increase the mass transfer rate; the design of the sedimentation tank can allow the oligomers that escape from the reaction system during the reaction to be recovered and re-enter the reactor to participate in the depolymerization reaction, thereby increasing the degree of reaction, reducing coking residues and increasing the yield of glycolide products. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0018] In the figure: 1. Reactor; 2. Coolant bypass pipe; 3. Motor; 4. Heating rod; 5. Stirring paddle; 6. Primary condenser; 7. Secondary condenser; 8. Sedimentation tank; 9. Water phase outlet; 10. Product outlet; 11. Sediment pipeline; 12. Steam inlet; 13. Steam outlet; 14. Feed pipeline; 15. Pressure balance pipe; 16. Stirring rod. DETAILED DESCRIPTION

[0019] In order to explain the technical content, structural features, achieved objectives and effects of the present invention in detail, the following is a detailed description in conjunction with the implementation modes and the accompanying drawings.

[0020] Example 1

[0021] An industrial device for producing glycolide products includes a reactor 1 with a jacket structure, a feed pipe 14 connected to the interior of the reactor 1, the top of the reactor 1 is connected to a primary condenser 6 through a pipe, the gas outlet of the primary condenser 6 is connected to a secondary condenser 7 through a pipe, and the gas outlet of the secondary condenser 7 is used for tail gas vacuuming; the liquid outlets of the primary condenser 6 and the secondary condenser 7 are connected in parallel to the top of a sedimentation tank 8 through pipes, a sediment pipe 11 is provided at the bottom of the sedimentation tank 8 and connected to the reactor 1, and a product outlet 10 is also provided at the bottom of the sedimentation tank 8; a motor 3 is provided at the top of the reactor 1, the motor 3 drives a stirring rod 16, and a stirring paddle 5 is provided at the bottom of the stirring rod 16.

[0022] A steam inlet 12 is arranged at the lower part of the shell side of the reactor 1 , and a steam outlet 13 is arranged at the upper part of the shell side of the reactor 1 .

[0023] A cooling liquid bypass pipe 2 is inserted from the outside into the bottom of the reactor 1 . The cooling liquid bypass pipe 2 is a spiral ascending structure in the reactor and extends from the upper part of the reactor 1 .

[0024] A plurality of heating rods 4 are arranged on the stirring rod 16 . The heating rods 4 in the same row are perpendicular to each other, and the heating rods 4 in the same column are parallel to each other.

[0025] The distance between the bottommost heating rod 4 and the stirring paddle 5 is 0.2 cm.

[0026] The distance between the blade of the stirring paddle 5 and the bottom of the reactor 1 is 0.2 cm, and the distance between the blade of the stirring paddle 5 and the inner wall of the reactor is 0.2 cm.

[0027] A water phase outlet 9 is arranged on the side wall of the sedimentation tank 8 . The water phase outlet 9 is an overflow weir with an adjustable height. The adjustable range of the overflow weir is 5.0 to 50.0 cm from the bottom of the sedimentation tank 8 .

[0028] A pressure balance pipe 15 is provided on the top of the side wall of the sedimentation tank 8 and is connected to the gas phase outlet of the secondary condenser 7 .

[0029] Furthermore, the inner wall of the reactor 1 is provided with a high temperature resistant and anti-material adhesion coating, and the coating material is polytetrafluoroethylene.

[0030] Furthermore, the motor 3, the heating rod 4 and the stirring paddle 5 are made of a metal material with high strength, high temperature resistance and good heat conduction, and the metal material is Hastelloy.

[0031] Furthermore, the blade type of the stirring paddle 5 is frame type.

[0032] Furthermore, the primary condenser 6 and the secondary condenser 7 are stainless steel shell and tube condensers.

[0033] Furthermore, the refrigerant temperature of the primary condenser 6 is 75-100°C, and the refrigerant temperature of the secondary condenser 7 is -5-10°C.

[0034] Example 2

[0035] The device described in Example 1 is used, and its operation process is as follows: after the reactor 1 is filled with materials through the feed pipe 14, the feed is closed, the steam inlet 12 is opened, the steam is provided by the workshop boiler, the pressure is not less than 0.6Mpa, the refrigerant in the coolant bypass pipe 2 is not higher than 0°C, and heating is started. When the temperature in the reactor exceeds 80°C, the motor 3 is turned on, the stirring rod starts to stir, and the temperature is continued to rise to 130°C. After the temperature stabilizes, the reaction is sealed and kept warm for 4 hours. After the reaction is completed, water is distilled at normal pressure, and the temperature is continued to rise to 170°C. When there is no more water in the reactor, the temperature is kept at 130°C. When liquid is obviously evaporated, start vacuuming to continue dehydration. At the same time, open the water phase outlet 9 and the sediment pipe 11 at the bottom of the sedimentation tank. When there is no liquid evaporated in the kettle, raise the temperature to 250°C and increase the vacuum degree to continue the reaction for 3.5 hours. At this time, a large amount of gas will evaporate in the kettle. After condensation by the condenser, a large amount of turbid liquid will be collected in the sedimentation tank 8. Close the sediment pipe 11 at the bottom of the sedimentation tank 8. After the lower product is completely precipitated, open the product outlet 10 to start discharging the product. After sampling and analysis, the product purity is 90.2%, which meets the product quality requirements.

Claims

1. An industrial device for producing glycolide products, characterized in that: The invention comprises a reactor (1) having a jacketed structure, a feed pipe (14) connected to the interior of the reactor (1), the top of the reactor (1) being connected to a primary condenser (6) through a pipe, the gas outlet of the primary condenser (6) being connected to a secondary condenser (7) through a pipe, and the gas outlet of the secondary condenser (7) being used for tail gas vacuuming; the liquid outlets of the primary condenser (6) and the secondary condenser (7) being connected in parallel to the top of a sedimentation tank (8) through pipes, a sediment pipe (11) being provided at the bottom of the sedimentation tank (8) and connected to the reactor (1), and a product outlet (10) being provided at the bottom of the sedimentation tank (8); a motor (3) being provided at the top of the reactor (1), the motor (3) driving a stirring rod (16), and a stirring paddle (5) being provided at the bottom of the stirring rod (16).

2. An industrial device for producing glycolide products according to claim 1, characterized in that: A steam inlet (12) is provided at the lower part of the shell side of the reactor (1), and a steam outlet (13) is provided at the upper part of the shell side of the reactor (1).

3. An industrial device for producing glycolide products according to claim 1, characterized in that: A cooling liquid bypass pipe (2) is inserted from the outside into the bottom of the reactor (1), and the cooling liquid bypass pipe (2) is a spiral ascending structure in the reactor and extends from the upper part of the reactor (1).

4. An industrialized device for producing glycolide products according to claim 1, characterized in that: A plurality of heating rods (4) are arranged on the stirring rod (16); the heating rods (4) in the same row are perpendicular to each other, and the heating rods (4) in the same column are parallel to each other.

5. An industrialized device for producing glycolide products according to claim 4, characterized in that: The distance between the bottommost heating rod (4) and the stirring paddle (5) is 0.2 to 5.0 cm.

6. An industrialized device for producing glycolide products according to claim 1, characterized in that: The distance between the blade of the stirring paddle (5) and the bottom of the reaction kettle (1) is 0.1 to 3.0 cm, and the distance between the blade and the inner wall of the reaction kettle is 0.1 to 5.0 cm.

7. An industrialized device for producing glycolide products according to claim 1, characterized in that: A water phase outlet (9) is arranged on the side wall of the sedimentation tank (8), and the water phase outlet (9) is an overflow weir with an adjustable height, and the adjustable range of the overflow weir is 5.0 to 50.0 cm from the bottom of the sedimentation tank (8).

8. An industrialized device for producing glycolide products according to claim 1, characterized in that: A pressure balance pipe (15) is provided on the top of the side wall of the sedimentation tank (8) and is connected to the gas phase outlet of the secondary condenser (7).

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