CN106928180B - Device and method for continuously refining glycolide from crude glycolide - Google Patents
Device and method for continuously refining glycolide from crude glycolide Download PDFInfo
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Abstract
The invention relates to a method for continuously refining glycolide from crude glycolide, which is characterized in that glycolide is continuously rectified and purified by a rectifying tower under high vacuum, firstly, crude glycolide liquid (L101) is introduced into a light component removal tower (1), low boiling point components in the crude glycolide are removed under the vacuum condition, light components (L102) are separated from the top of the light component removal tower (1), the light components are sent into a light liquid storage tank (6) after passing through a condenser (4) at the top of the light component removal tower, heavy components (L103) obtained from the bottom of the light component removal tower (1) enter a refining tower (2) for further rectification through a material cooler (9) and a circulating pump (10) at the bottom of the tower, glycolide products (L104) obtained from the top of the tower are sent into a glycolide storage tank (13) after passing through a condenser (12) at the top of the refining tower, and glycolic acid oligomers (L105) are obtained from the bottom of the refining tower (2). Compared with the prior art, the glycolide obtained by separation has high purity, no additional solvent is added in the separation process, the continuous industrial production requirement is met, and the separation cost is low.
Description
Technical Field
The invention relates to the field of purification of glycolide, and in particular relates to a device and a method for continuously refining glycolide from crude glycolide.
Background
Polyglycolide is a high molecular material with biodegradability and excellent gas cutting barrier property, and the polyglycolide and the poly (lactide-co-glycolide) copolymer have important positions in many fields of operation suture lines, artificial skin and blood vessels, bone fixation and repair, drug controlled release and the like.
Usually, high molecular weight polyglycolide is prepared by ring-opening polymerization of high purity glycolide.
On the other hand, in general, glycolide is obtained by depolymerizing a glycolic acid oligomer or a methyl glycolate oligomer, and the glycolide obtained in this way contains impurities, and the glycolic acid impurities include: methanol, glycolic acid or methyl glycolate monomers, glycolic acid dimers, and the like. Patent CN103664866 mentions that the presence of water enables hydrolysis of glycolide to give glycolic acid and hydrolytic cleavage of the polyglycolide molecular chains; the presence of an acidic substance such as glycolic acid or a dimer thereof degrades glycolic acid molecular chains by acid hydrolysis. Therefore, the impurity-containing glycolide needs to be purified and refined before being used.
There are many purification methods, and US patent nos. 5223630, CN100999516, and CN101054371 describe recrystallization purification using various solvents, such as ethyl acetate, isopropanol, carbon tetrachloride, etc. Namely, the glycolide is purified by a solvent recrystallization method, the recrystallization purification operation is simple, and the process is mature. However, the purity of the glycolide obtained by primary recrystallization is not high, and multiple recrystallization is needed to obtain a glycolide product with high purity, so that the yield of the glycolide is generally low, and the solvent needs to be recycled, thereby increasing the equipment investment and the energy consumption.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a device and a method for continuously refining glycolide from crude glycolide, which do not add extra solvent, meet the continuous industrial production requirements and have low cost.
The purpose of the invention can be realized by the following technical scheme: a method for continuously refining glycolide from crude glycolide is to continuously rectify and purify the glycolide by a rectifying tower under high vacuum, and specifically comprises the following steps:
(1) introducing the crude glycolide liquid into a light component removal tower, removing low-boiling components in the crude glycolide under vacuum conditions, separating light components from the top of the light component removal tower, sending the light components into a light liquid storage tank after passing through a condenser at the top of the light component removal tower, and sending heavy components obtained from the bottom of the light component removal tower into a refining tower through a material cooler and a circulating pump at the bottom of the tower;
(2) the heavy component is further rectified in the refining tower, the glycolide product obtained at the tower top is sent into a glycolide storage tank after passing through a condenser at the tower top of the refining tower, and the glycolic acid oligomer is obtained at the tower bottom of the refining tower.
The basic technical principle of the invention is that under the high vacuum environment, the volatility of each component in the crude glycolide liquid is utilized to be different, partial vaporization and partial condensation are carried out for many times in the rectifying tower, finally, the light component rich in the low boiling point component is collected in the vapor phase at the top of the tower, and the heavy component rich in the high boiling point component is collected in the liquid phase at the bottom of the tower, thereby achieving the purpose of separating and purifying each component. Specifically, under a high vacuum environment, light components (including water and glycolic acid) are removed from the top of a first rectifying tower, heavy components (glycolic acid oligomer) are removed from the bottom of a second rectifying tower, and a high-purity glycolide product is collected from the top of the second rectifying tower.
The working pressure at the top of the light component removal tower is 60-500 Pa, the working pressure at the bottom of the light component removal tower is 1500-5000 Pa, the temperature is less than or equal to 200 ℃, and the reflux ratio is 0.4-5.0.
The working pressure at the top of the refining tower is 60-500 Pa, the working pressure at the bottom of the refining tower is 800-1500 Pa, the temperature is less than or equal to 210 ℃, and the reflux ratio is 0.9-5.0.
The crude glycolide liquid is a liquid in a crude glycolide molten state, and is fed from the middle lower part of the light component removal tower.
The light component removal tower is provided with 8 tower plates, and the crude glycolide liquid enters from the sixth tower plate of the light component removal tower (1).
The crude glycolide liquid comprises 65-98 wt% of glycolide, 1-25 wt% of glycolic acid, 0.5-1.5 wt% of water, 0.5-5 wt% of glycolic acid oligomer and 0-3.5 wt% of other free acids.
The heavy component comprises glycolide, glycolic acid oligomer, water and free acid, wherein the concentration of the glycolide is 85-99 wt%, and the concentration of the glycolic acid oligomer is 0-5 wt%.
The other free acids mainly comprise free methoxy acetic acid and free oxalic acid.
And after 60 wt% of the materials in the heavy components enter a reboiler for vaporization, returning the vaporized materials into the light component removal tower, and exchanging heat of the rest heavy components through a material cooler to reduce the temperature to about 170-180 ℃, and inputting the rest heavy components from a sixth tower plate of the rectifying tower through a tower top circulating pump, wherein the total number of the rectifying tower is 9.
The glycolide product comprises water, glycolic acid and glycolide, the concentration of the glycolide is more than or equal to 97 wt%, the water content is less than 500ppm, the glycolic acid content is less than 100ppm, the purified glycolide obtained from the steam at the top of the refining tower or in the side line of the refining tower preferably has the purity of more than or equal to 99.1 wt%, and the water content is less than or equal to 500 ppm.
A device for continuously refining glycolide from crude glycolide comprises a light component removal tower, a refining tower, a tower top condenser of the light component removal tower, a light liquid storage tank, a material cooler, a tower bottom circulating pump, a tower top condenser of the refining tower and a glycolide storage tank;
the top of the light component removal tower is sequentially connected with a light component removal tower top condenser and a light liquid storage tank, a tower kettle of the light component removal tower is sequentially connected with a material cooler, a tower bottom circulating pump and an inlet of a refining tower, and the top of the refining tower is sequentially connected with a refining tower top condenser and a glycolide storage tank;
the top of the light component removal tower is provided with a light component removal tower internal reflux condenser for condensing part of gas phase to reflux, and the bottom of the light component removal tower is provided with a light component removal tower reboiler for gasifying part of liquid phase and returning the liquid phase to the bottom of the light component removal tower;
the top of the refining tower is provided with a reflux condenser in the refining tower, which is used for condensing part of gas phase to reflux, and the bottom of the refining tower is provided with a reboiler of the refining tower, which is used for gasifying part of liquid phase and returning the liquid phase to the bottom of the refining tower.
The light component removal tower and the refining tower are both packed towers.
The top of the light liquid storage tank is provided with a first vacuum pipeline for adjusting the pressure of the light component removal tower, and the bottom of the light liquid storage tank is provided with a light component product pipeline for conveying light component products;
the top of the glycolide storage tank is provided with a second vacuum pipeline for adjusting the pressure of the refining tower, and the bottom of the glycolide storage tank is provided with a glycolide product pipeline for conveying glycolide products.
Compared with the prior art, the beneficial effects of the invention are embodied in the following aspects:
(1) the purity of the glycolide can reach more than 99.1 percent, and the yield reaches more than 90 percent.
(2) The whole process of the rectification operation of the invention is continuous, the product quality is stable, unnecessary material loss is reduced and avoided, and raw materials are saved.
(3) The invention adopts a method of continuous high vacuum rectification with two series-connected towers. The method does not introduce solvent or other liquid, so the method has no problems of solvent or waste liquid treatment, environmental pollution and the like.
(4) The purification process of the invention is realized in the rectifying tower, and the rectifying tower is simple, convenient and safe to operate.
Drawings
FIG. 1 is a schematic diagram of the connection of the present invention.
Wherein, 1 is a light component removal tower, 2 is a refining tower, 3 is a light component removal tower internal reflux condenser, 4 is a light component removal tower top condenser, 5 is a first vacuum pipeline, 6 is a light liquid storage tank, 7 is a light component product pipeline, 8 is a light component removal tower reboiler, 9 is a material cooler, 10 is a tower bottom circulating pump, 11 is a refining tower internal reflux condenser, 12 is a refining tower top condenser, 13 is a glycolide storage tank, 14 is a second vacuum pipeline, 15 is a glycolide product pipeline, 16 is a refining tower reboiler, L101 is crude glycolide liquid, L102 is a light component, L103 is a heavy component, L104 is a glycolide product, and L105 is a glycolic acid oligomer.
Detailed Description
The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.
The intrinsic viscosity of polyglycolide was measured by a Ubbelohde intrinsic viscometer. The water content was determined by a karl fischer moisture meter. The free acid content was determined by chemical titration. Low molecular weight polyglycolides such as glycolic acid dimers, polymers, glycolic acid is determined by GC.
In order to obtain a high molecular weight polyglycolide, it is necessary to reduce the amount of hydroxyl impurities in the glycolide as much as possible, and these hydroxyl impurities are mainly derived from methoxyacetic acid, oxalic acid, glycolic acid, and the like. Hereinafter, these substances having hydroxyl group-containing impurities are collectively referred to as glycolic acid impurities. Glycolide containing different mass percentages of impurities was polymerized into polyglycolide to illustrate the effect of glycolide impurities on the molecular weight of the polyglycolide. The polymerization was carried out at 195 ℃ under a dry nitrogen atmosphere using 0.06 wt% zinc acetate as catalyst.
The molecular weight of polyglycolide is indirectly described using intrinsic viscosity:
| intrinsic viscosity range dL/g | Corresponding weight average molecular weight Mw (ten thousand) |
| 0.30～0.50 | 1～3 |
| 0.50～0.70 | 3～6 |
| 0.70～1.00 | 6～10 |
| 1.00～1.50 | 10～25 |
| >1.5 | >25 |
Glycolic acid impurity-polyglycolide intrinsic viscosity:
| glycolic acid impurity content (wt%) | Polyglycolide intrinsic viscosity (dL/g) |
| 0.10 | 1.56 |
| 0.16 | 1.33 |
| 0.52 | 1.09 |
| 0.98 | 0.81 |
| 1.51 | 0.43 |
Example 1
As shown in FIG. 1, the apparatus for continuously purifying glycolide from crude glycolide. The device comprises a light component removal tower 1, a refining tower 2, a condenser 4 at the top of the light component removal tower, a light liquid storage tank 6, a material cooler 9, a circulating pump 10 at the bottom of the tower, a condenser 12 at the top of the refining tower and a glycolide storage tank 13;
the top of the light component removing tower 1 is sequentially connected with a light component removing tower top condenser 4 and a light liquid storage tank 6, the tower bottom of the light component removing tower 1 is sequentially connected with a material cooler 9, a tower bottom circulating pump 10 and an inlet of the refining tower 2, and the top of the refining tower 2 is sequentially connected with a refining tower top condenser 12 and a glycolide storage tank 13;
the top of the light component removal tower 1 is provided with a light component removal tower internal reflux condenser 3 for condensing part of gas phase for reflux, and the bottom of the light component removal tower 1 is provided with a light component removal tower reboiler 8 for gasifying part of liquid phase and returning the liquid phase to the bottom of the light component removal tower 1;
the top of the refining tower 2 is provided with a refining tower internal reflux condenser 12 for condensing part of gas phase for reflux, and the bottom of the refining tower 2 is provided with a refining tower reboiler 16 for gasifying part of liquid phase and returning the liquid phase to the bottom of the refining tower 2; the light component removal tower 1 and the refining tower 2 are both packed towers.
A first vacuum pipeline 5 is arranged at the top of the light liquid storage tank 6 and used for adjusting the pressure of the light component removal tower 1, and a light component product pipeline 7 is arranged at the bottom of the light liquid storage tank 6 and used for conveying light component products; the top of the glycolide storage tank 13 is provided with a second vacuum pipeline 14 for adjusting the pressure of the refining tower 2, and the bottom of the glycolide storage tank 13 is provided with a glycolide product pipeline 15 for conveying glycolide products.
A method for continuously refining glycolide from crude glycolide, comprising the following steps:
(1) introducing 500kg/h of crude glycolide liquid L101 into a 6 th tray of a light component removal tower 1, wherein the total number of the light component removal tower 1 is 8 trays, the reflux ratio of the light component removal tower is 0.4, the top pressure of the light component removal tower is 60Pa, and the bottom pressure of the light component removal tower is 1500 Pa; the temperature of steam at the top is about 150 ℃, the temperature of the bottom of the light component removal tower is about 200 ℃, a light component L102 is obtained at the top of the tower after rectification, the light component is sent into a light liquid storage tank 6 after passing through a condenser 4 at the top of the light component removal tower, a heavy component L103 obtained at the bottom of the light component removal tower 1 is cooled to the temperature of 170 ℃ through a material cooler 9, and then the heavy component is sent into a refining tower 2 through a circulating pump 10 at the bottom of the tower;
(2) the heavy component L103 enters from the 6 th tower plate in the refining tower 2, the refining tower 2 has 9 tower plates in total, the reflux ratio adopted by the refining tower 2 is 0.9, the tower top pressure of the refining tower 2 is 60Pa, and the tower bottom pressure of the refining tower 2 is 800 Pa; the steam temperature at the top of the refining tower 2 is about 160 ℃, the temperature at the bottom of the refining tower 2 is about 210 ℃, the glycolide product L104 obtained at the tower top passes through a condenser 12 at the tower top of the refining tower and then is sent into a glycolide storage tank 13, and the glycolic acid oligomer L105 is obtained at the tower bottom of the refining tower 2.
The contents of each component in L101, L102, L103, L104 and L105 were analyzed as shown in the following tables.
| Glycolic acid wt.% | Glycolide wt.% | Glycolic acid oligomer wt% | Free acid wt% | Ppm of water | |
| L101 | 25 | 65 | 5 | 3.5 | 15000 |
| L102 | 82.6 | 7.9 | 0 | 7.5 | 20000 |
| L103 | 4.6 | 85 | 5 | 5.37 | 300 |
| L104 | 0.01 | 99.1 | 0.44 | 0.41 | 433 |
| L105 | 0 | 14.7 | 84.3 | 1 | 0 |
And discharging from the top of the refining tower, and sampling to perform a ring-opening polymerization experiment of polyglycolide. And the intrinsic viscosity was measured, and the results were: 1.0L/g, indicating that the concentration of the purified glycolide obtained in this example was 99.1%.
Example 2
A method for continuously refining glycolide from crude glycolide, comprising the following steps:
(1) introducing 500kg/h of crude glycolide liquid into the 6 th tower plate of a light component removal tower, wherein the total number of the light component removal tower is 8, the reflux ratio of the light component removal tower is 5.0, the top pressure of the light component removal tower is 500Pa, and the bottom pressure of the light component removal tower is 5000 Pa; the temperature of the steam at the top is about 150 ℃, the temperature of the bottom of the light component removal tower is about 200 ℃, light components are obtained at the top of the tower after rectification, the light components are sent into a light liquid storage tank after passing through a condenser at the top of the light component removal tower, heavy components obtained at the bottom of the light component removal tower are cooled to 180 ℃ through a material cooler, and then the heavy components are pumped into a refining tower through a circulating pump at the bottom of the tower;
(2) the heavy component enters from the sixth tower plate in the refining tower, the refining tower has 9 tower plates, the reflux ratio adopted by the refining tower is 5.0, the tower top pressure of the refining tower is 500Pa, and the tower bottom pressure of the refining tower is 1500 Pa; the steam temperature at the top of the refining tower is about 160 ℃, the temperature at the bottom of the refining tower is about 210 ℃, the glycolide product obtained at the top of the tower passes through a condenser at the top of the refining tower and then is sent into a glycolide storage tank, and the glycolic acid oligomer is obtained at the bottom of the refining tower.
The contents of each component in L101, L102, L103, L104 and L105 were analyzed as shown in the following tables.
And discharging from the top of the refining tower, and sampling to perform a ring-opening polymerization experiment of polyglycolide. And the intrinsic viscosity was measured, and the results were: 1.69L/g.
Example 3
A method for continuously refining glycolide from crude glycolide, comprising the following steps:
(1) introducing 500kg/h of crude glycolide liquid into the 6 th tower plate of a light component removal tower, wherein the total number of the light component removal tower is 8, the reflux ratio of the light component removal tower is 5.0, the top pressure of the light component removal tower is 500Pa, and the bottom pressure of the light component removal tower is 2500 Pa; the temperature of the steam at the top is about 154 ℃, the temperature of the bottom of the light component removal tower is about 196 ℃, light components are obtained at the top of the tower after rectification, the light components are sent into a light liquid storage tank after passing through a condenser at the top of the light component removal tower, heavy components obtained at the bottom of the light component removal tower are cooled to 175 ℃ through a material cooler, and then the heavy components are pumped into a refining tower through a circulating pump at the bottom of the tower;
(2) the heavy component enters from the sixth tower plate in the refining tower, the refining tower has 9 tower plates, the reflux ratio adopted by the refining tower is 5.0, the tower top pressure of the refining tower is 500Pa, and the tower bottom pressure of the refining tower is 1500 Pa; the steam temperature at the top of the refining tower is about 170 ℃, the temperature at the bottom of the refining tower is about 200 ℃, the glycolide product obtained at the top of the refining tower passes through a condenser at the top of the refining tower and then is sent into a glycolide storage tank, and the glycolic acid oligomer is obtained at the bottom of the refining tower.
The contents of each component in L101, L102, L103, L104 and L105 were analyzed as shown in the following tables.
| Glycolic acid wt.% | Glycolide wt.% | Glycolic acid oligomer wt% | Other free acids wt.% | Ppm of water | |
| L101 | 2.07 | 92.77 | 4.05 | 0.592 | 5180 |
| L102 | 76.93 | 2.48 | 0 | 0.4304 | 201596 |
| L103 | 0 | 95.25 | 4.25 | 0.4843 | 157 |
| L104 | 0 | 99.28 | 0.12 | 0.5792 | 208 |
| L105 | 0 | 13.82 | 85.18 | 0.9911 | 89 |
And discharging from the top of the refining tower, and sampling to perform a ring-opening polymerization experiment of polyglycolide. And the intrinsic viscosity was measured, and the results were: 1.5 dL/g.
Example 4
A method for continuously refining glycolide from crude glycolide, comprising the following steps:
(1) introducing 500kg/h of crude glycolide liquid into the 6 th tower plate of a light component removal tower, wherein the total number of the light component removal tower is 8, the reflux ratio of the light component removal tower is 5.0, the top pressure of the light component removal tower is 300Pa, and the bottom pressure of the light component removal tower is 1500 Pa; the temperature of the steam at the top is about 146 ℃, the temperature of the bottom of the light component removal tower is about 180 ℃, light components are obtained at the top of the tower after rectification, the light components are sent into a light liquid storage tank after passing through a condenser at the top of the light component removal tower, heavy components obtained at the bottom of the light component removal tower are cooled to 175 ℃ through a material cooler, and then the heavy components are pumped into a refining tower through a circulating pump at the bottom of the tower;
(2) the heavy component enters from the sixth tower plate in the refining tower, the refining tower has 9 tower plates, the reflux ratio adopted by the refining tower is 0.9, the tower top pressure of the refining tower is 300Pa, and the tower bottom pressure of the refining tower is 1200 Pa; the steam temperature at the top of the refining tower is about 160 ℃, the temperature at the bottom of the refining tower is about 195 ℃, the glycolide product obtained at the top of the refining tower passes through a condenser at the top of the refining tower and then is sent into a glycolide storage tank, and the glycolic acid oligomer is obtained at the bottom of the refining tower.
The contents of each component in L101, L102, L103, L104 and L105 were analyzed as shown in the following tables.
And discharging from the top of the refining tower, and sampling to perform a ring-opening polymerization experiment of polyglycolide. And the intrinsic viscosity was measured, and the results were: 1.05 dL/g.
Example 5
A method for continuously refining glycolide from crude glycolide, comprising the following steps:
(1) introducing 500kg/h of crude glycolide liquid into the 6 th tower plate of a light component removal tower, wherein the total number of the light component removal tower is 8, the reflux ratio of the light component removal tower is 5.0, the top pressure of the light component removal tower is 500Pa, and the bottom pressure of the light component removal tower is 1500 Pa; the temperature of the steam at the top is about 154 ℃, the temperature of the bottom of the light component removal tower is about 185 ℃, light components are obtained at the top of the tower after rectification, the light components are sent into a light liquid storage tank after passing through a condenser at the top of the light component removal tower, heavy components obtained at the bottom of the light component removal tower are cooled to 175 ℃ through a material cooler, and then the heavy components are pumped into a refining tower through a circulating pump at the bottom of the tower;
(2) the heavy component enters from the sixth tower plate in the refining tower, the refining tower has 9 tower plates, the reflux ratio adopted by the refining tower is 5.0, the tower top pressure of the refining tower is 500Pa, and the tower bottom pressure of the refining tower is 1500 Pa; the steam temperature at the top of the refining tower is about 171 ℃, the temperature at the bottom of the refining tower is about 202 ℃, the glycolide product obtained at the top of the tower passes through a condenser at the top of the refining tower and then is sent into a glycolide storage tank, and the glycolic acid oligomer is obtained at the bottom of the refining tower.
The contents of each component in L101, L102, L103, L104 and L105 were analyzed as shown in the following tables.
| Glycolic acid wt.% | Glycolide wt.% | Glycolic acid oligomer wt% | Other free acids wt.% | Ppm of water | |
| L101 | 2.30 | 92.64 | 4.25 | 0.1977 | 6123 |
| L102 | 77.36 | 2.63 | 0 | 0.998 | 190120 |
| L103 | 0 | 95.39 | 4.11 | 0.4898 | 102 |
| L104 | 0 | 98.99 | 0.69 | 0.3074 | 126 |
| L105 | 0 | 22.13 | 77.57 | 0.2922 | 78 |
And discharging from the top of the refining tower, and sampling to perform a ring-opening polymerization experiment of polyglycolide. And the intrinsic viscosity was measured, and the results were: 1.2 dL/g.
Claims (8)
1. A method for continuously refining glycolide from crude glycolide is characterized in that the method is used for continuously rectifying and purifying the glycolide by a rectifying tower under high vacuum, and specifically comprises the following steps:
(1) introducing a crude glycolide liquid (L101) into a light component removal tower (1), removing low-boiling components in the crude glycolide under a vacuum condition, separating a light component (L102) from the top of the light component removal tower (1), sending the light component to a light liquid storage tank (6) after passing through a condenser (4) at the top of the light component removal tower, and sending a heavy component (L103) obtained from the bottom of the light component removal tower (1) into a refining tower (2) through a material cooler (9) and a circulating pump (10) at the bottom of the tower;
(2) further rectifying the heavy component (L103) in a refining tower (2), sending a glycolide product (L104) obtained at the tower top into a glycolide storage tank (13) after passing through a condenser (12) at the tower top of the refining tower, and obtaining a glycolic acid oligomer (L105) at the tower bottom of the refining tower (2);
the working pressure at the top of the light component removal tower (1) is 60-500 Pa, the working pressure at the bottom of the tower is 1500-5000 Pa, the temperature is less than or equal to 200 ℃, and the reflux ratio is 0.4-5.0;
the working pressure at the top of the refining tower (2) is 60-500 Pa, the working pressure at the bottom of the refining tower is 800-1500 Pa, the temperature is less than or equal to 210 ℃, and the reflux ratio is 0.9-5.0.
2. The method for continuously refining glycolide from crude glycolide according to claim 1, wherein the crude glycolide liquid (L101) is a liquid in a molten state of crude glycolide, and the crude glycolide liquid (L101) is fed from the middle-lower part of the light component removal column (1).
3. A process for the continuous purification of glycolide from crude glycolide according to claim 2, characterized in that the lightness-removing column (1) has 8 trays, and the crude glycolide liquid (L101) enters from the sixth tray of the lightness-removing column (1).
4. The method for continuously refining glycolide from crude glycolide according to claim 1, wherein the crude glycolide solution (L101) comprises the components of 65 to 98 wt% of glycolide, 1 to 25 wt% of glycolic acid, 0.5 to 1.5 wt% of water, 0.5 to 5 wt% of glycolic acid oligomers, and 0 to 3.5 wt% of free methoxy acetic acid and/or free oxalic acid;
the heavy component (L103) comprises glycolide, glycolic acid oligomer, water and free acid, wherein the concentration of the glycolide is 85-99 wt%, and the concentration of the glycolic acid oligomer is 1-15 wt%.
5. The method for continuously refining glycolide from crude glycolide according to claim 1, wherein 60 wt% of the heavy component (L103) enters a reboiler (8) of the light ends removal column for vaporization, and then returns to the light ends removal column (1), the remaining heavy component (L103) is subjected to heat exchange through a material cooler (9), the temperature is reduced to 170-180 ℃, and then the residual heavy component is fed from the sixth tray of the refining column (2) through a top circulation pump (10), and the rectifying column (2) has 9 trays in total.
6. The method for continuously refining glycolide from crude glycolide according to claim 1, wherein the glycolide product (L104) comprises water, glycolic acid and glycolide, the concentration of glycolide is not less than 97 wt%, the moisture content is less than 500ppm, and the glycolic acid content is less than 100 ppm.
7. An apparatus for a process for the continuous refining of glycolide from crude glycolide according to any of claims 1 to 6, characterized in that the apparatus comprises a lightness-removing column (1), a refining column (2), a lightness-removing column overhead condenser (4), a light liquid storage tank (6), a material cooler (9), a column bottom circulation pump (10), a refining column overhead condenser (12) and a glycolide storage tank (13);
the top of the light component removing tower (1) is sequentially connected with a light component removing tower top condenser (4) and a light liquid storage tank (6), the tower kettle of the light component removing tower (1) is sequentially connected with a material cooler (9), a tower bottom circulating pump (10) and an inlet of a refining tower (2), and the top of the refining tower (2) is sequentially connected with a refining tower top condenser (12) and a glycolide storage tank (13);
the top of the light component removal tower (1) is provided with a light component removal tower internal reflux condenser (3) for condensing part of gas phase for reflux, and the bottom of the light component removal tower (1) is provided with a light component removal tower reboiler (8) for gasifying part of liquid phase and returning the liquid phase to the bottom of the light component removal tower (1);
the top of the refining tower (2) is provided with a refining tower internal reflux condenser (12) for condensing part of gas phase for reflux, and the bottom of the refining tower (2) is provided with a refining tower reboiler (16) for gasifying part of liquid phase and returning the liquid phase to the bottom of the refining tower (2);
the light component removal tower (1) and the refining tower (2) are both packed towers.
8. The device according to claim 7, characterized in that the top of the light liquid storage tank (6) is provided with a vacuum line (5) for adjusting the pressure of the light component removal tower (1), and the bottom of the light liquid storage tank (6) is provided with a light component product pipeline (7) for conveying light component products; the top of the glycolide storage tank (13) is provided with a second vacuum pipeline (14) for adjusting the pressure of the refining tower (2), and the bottom of the glycolide storage tank (13) is provided with a glycolide product pipeline (15) for conveying glycolide products.
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| CN115246811A (en) * | 2021-04-28 | 2022-10-28 | 上海浦景化工技术股份有限公司 | Continuous production method of purified glycolide |
| CN115124501B (en) * | 2022-08-30 | 2023-02-03 | 深圳市迈启生物材料有限公司 | Method and device for preparing glycolide |
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| CN101696203A (en) * | 2009-10-26 | 2010-04-21 | 江苏科技大学 | Method for continuously refining L-lactide from crude L-lactide |
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| US4650851A (en) * | 1986-03-19 | 1987-03-17 | Pfizer Hospital Products Group, Inc. | Purification of glycolide |
| US5223630A (en) * | 1989-10-10 | 1993-06-29 | E. I. Du Pont De Nemours And Company | Glycolide purification process |
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