A system for continuous purification of glycine

Abstract

This utility model discloses a continuous purification system for glycine. The glycine reaction solution enters a first low-temperature crystallization vessel or a second low-temperature crystallization vessel through a reaction solution inlet pipe. The glycine reaction solution is cooled and crystallized in the first or second low-temperature crystallization vessel. After crystallization, it is centrifuged in a first centrifuge to obtain a mother liquor and a first wet product. The first wet product is discharged into a pulping vessel. The mother liquor can be reused. Methanol solution is added to the pulping vessel to fully dissolve the mother liquor to obtain a solution. The solution flows into a second centrifuge for centrifugation to obtain a methanol mother liquor and a second wet product. The second wet product is discharged and dried to obtain the glycine product. The methanol mother liquor is discharged into a flash evaporator to flash distill to obtain methanol gas and ammonium chloride concentrate. The methanol gas enters a condenser to condense and obtain a methanol solution, which flows into the pulping vessel. The ammonium chloride concentrate is discharged through an ammonium chloride concentrate outlet pipe.

Description

Technical Field

[0001] This invention belongs to the field of glycine preparation technology, specifically relating to a system for the continuous purification of glycine. Background Technology

[0002] Glycine has a wide range of applications in the chemical, pesticide, pharmaceutical, food, and feed industries. Depending on the raw materials used, glycine production processes can be categorized into the chloroacetic acid ammonolysis method, the Strecker process, and the Hyne process. Because chloroacetic acid is widely available, the chloroacetic acid ammonolysis method is the most common glycine production process in China. This process begins with chloroacetic acid reacting with ammonia under the catalysis of hexamethylenetetramine to produce a mixture of glycine and ammonium chloride. Then, taking advantage of the different solubilities of glycine and ammonium chloride in methanol-water solutions, methanol is used to crystallize the ammonium chloride. Finally, the glycine is dehydrated using a centrifuge and then dried to obtain the finished glycine product. The separation process of the product glycine and the byproduct ammonium chloride is energy-intensive, accounting for approximately 80% of the total energy consumption in the existing glycine production process. Furthermore, the separated glycine product still contains some ammonium chloride. The chloride ion content in the glycine product directly determines its quality grade.

[0003] In order to reduce the ammonium chloride content in glycine products and ultimately improve product quality, existing technologies typically involve repeated recrystallization of glycine products. This not only increases energy consumption but also results in some product being lost with the mother liquor during repeated recrystallization, leading to a significant reduction in product yield.

[0004] Chinese patent CN115124436A, published on September 30, 2022, discloses a continuous production process for glycine. Chloroacetic acid and hexamethylenetetramine are dissolved in water, and then ammonia gas is introduced to carry out an ammoniation reaction, yielding a mixed solution. The mixed solution is cooled and crystallized, then centrifuged to obtain a stock solution and crystals. The stock solution undergoes a first-stage electrodialysis treatment to obtain a first-stage dialysis solution and an organic liquid. The crystals are added to a saturated glycine solution for mixing and dissolution, and then centrifuged to obtain a glycine product and a saturated solution. The saturated solution undergoes a second-stage electrodialysis treatment to obtain a second-stage dialysis solution and a saturated organic liquid. The first-stage and second-stage dialysis solutions are evaporated to obtain ammonium chloride and water. This method involves a complex production system and has high production costs. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a continuous purification system for glycine. The glycine reaction solution enters a first low-temperature crystallization vessel or a second low-temperature crystallization vessel through a reaction solution inlet pipe. The glycine reaction solution is cooled and crystallized in the first or second low-temperature crystallization vessel. After crystallization, it enters a first centrifuge through a first connecting pipe or a second connecting pipe for the first centrifuge. The first centrifuge yields a mother liquor and a first wet product. The first wet product is discharged into a pulping vessel through a first discharge pipe. The mother liquor can be reused. Methanol solution is added to the pulping vessel through a methanol solution inlet pipe for complete dissolution to obtain a solution. The solution flows into a second centrifuge through a third connecting pipe for the second centrifuge. The second centrifuge yields a methanol mother liquor and a second wet product. The second wet product is discharged through a second discharge pipe and dried to obtain the glycine product. The methanol mother liquor is discharged into a flash tank through a methanol mother liquor outlet pipe for flash evaporation to obtain methanol gas and ammonium chloride concentrate. The methanol gas enters a condenser through a gas phase outlet pipe for condensation to obtain a methanol solution, which flows into the pulping vessel through a methanol solution inlet pipe. The ammonium chloride concentrate is discharged through an ammonium chloride concentrate outlet pipe and dried to obtain ammonium chloride.

[0006] The objective of this utility model is achieved through the following technical solution: A continuous purification system for glycine includes a reaction liquid inlet pipe connected to a first low-temperature crystallization vessel and a second low-temperature crystallization vessel. The first low-temperature crystallization vessel is connected to a first centrifuge via a first connecting pipe, and the second low-temperature crystallization vessel is connected to the first centrifuge via a second connecting pipe. The centrifuge is equipped with a first discharge pipe and a mother liquor discharge pipe. The first discharge pipe is connected to a pulping vessel. The pulping vessel is equipped with a third connecting pipe and a methanol solution inlet pipe, which is connected to a second centrifuge. The second centrifuge is equipped with a second discharge pipe and a methanol mother liquor discharge pipe, which is connected to a flash tank. The flash tank is connected to a gas phase outlet pipe and a concentrated ammonium chloride outlet pipe, and the gas phase outlet pipe is connected to the methanol solution inlet pipe via a condenser.

[0007] Preferably, the reaction liquid inlet pipe is connected to the glycine reaction system.

[0008] Preferably, the glycine reaction system includes a first-stage reactor and a second-stage reactor. The first-stage reactor is equipped with a hexamethylenetetramine solution inlet pipe, a chloroacetic acid solution inlet pipe, a first ammonia gas inlet pipe, a first tail gas outlet pipe, and a feed pipe. The first-stage reactor is connected to the second-stage reactor through the feed pipe. The second-stage reactor is equipped with a second ammonia gas inlet pipe, a second tail gas outlet pipe, and a reaction liquid inlet pipe.

[0009] Preferably, the reaction liquid inlet pipe is connected to the first reaction liquid branch pipe and the second reaction liquid branch pipe, and the first reaction liquid branch pipe and the second reaction liquid branch pipe are respectively connected to the first low-temperature crystallization vessel and the second low-temperature crystallization vessel.

[0010] Preferably, the hexamethylenetetramine solution inlet tube is connected to the mother liquor outlet tube.

[0011] Preferably, temperature sensors are installed on the first-stage reactor, the second-stage reactor, the first low-temperature crystallization reactor, the second low-temperature crystallization reactor, and the pulping reactor.

[0012] Preferably, the first-stage reactor, the second-stage reactor, the first low-temperature crystallization reactor, the second low-temperature crystallization reactor, and the pulping reactor are all equipped with stirring devices.

[0013] Preferably, the first connecting pipe, the second connecting pipe, the mother liquor outlet pipe, the first discharge pipe, the third connecting pipe, the methanol solution inlet pipe, the second discharge pipe, the methanol mother liquor outlet pipe, the gas phase outlet pipe, the ammonium chloride concentrated solution outlet pipe, the hexamethylenetetramine solution inlet pipe, the chloroacetic acid solution inlet pipe, the first ammonia gas inlet pipe, the first tail gas outlet pipe, the feed pipe, the first reaction liquid branch pipe, and the second reaction liquid branch pipe are all equipped with feed valves.

[0014] Preferably, flow meters are installed on the mother liquor outlet pipe, methanol solution inlet pipe, hexamethylenetetramine solution inlet pipe, chloroacetic acid solution inlet pipe, first ammonia inlet pipe, and second ammonia inlet pipe.

[0015] The beneficial effects of this technical solution are as follows: I. This utility model provides a continuous purification system for glycine. The glycine reaction solution enters a first or second low-temperature crystallization vessel through a reaction solution inlet pipe. The glycine reaction solution undergoes cooling and crystallization in the first or second low-temperature crystallization vessel. After crystallization, it enters a first centrifuge through a first or second connecting pipe for a first centrifuge treatment. The first centrifugation yields a mother liquor and a first wet product. The first wet product is discharged into a pulping vessel through a first discharge pipe. The mother liquor can be reused. Methanol solution is added to the pulping vessel through a methanol solution inlet pipe for complete dissolution to obtain a solution. The solution flows into the second centrifuge through the third connecting pipe for a second centrifugation process. The second centrifugation yields a methanol mother liquor and a second wet product. The second wet product (which includes glycine and a methanol mother liquor containing ammonium chloride and a small amount of glycine) is discharged through the second discharge pipe and then dried to obtain the glycine product. The methanol mother liquor is discharged into a flash tank through the methanol mother liquor outlet pipe for flash evaporation to obtain methanol gas and ammonium chloride concentrate. The methanol gas enters the condenser through the gas phase outlet pipe and is condensed to obtain a methanol solution, which flows into the pulping kettle through the methanol solution inlet pipe. The ammonium chloride concentrate is discharged through the ammonium chloride concentrate outlet pipe and dried to obtain ammonium chloride.

[0016] II. The present invention provides a continuous purification system for glycine. Urotropin solution, chloroacetic acid solution and ammonia gas are introduced into a first-stage reactor through a urotropin solution inlet pipe, a chloroacetic acid solution inlet pipe and a first ammonia gas inlet pipe, respectively, to carry out a first-stage reaction. After the first-stage reaction is completed, the mixture is introduced into a second-stage reactor through a second ammonia gas inlet pipe to carry out a second-stage reaction to obtain a glycine reaction solution (including urotropin, glycine and ammonium chloride, etc.).

[0017] III. The present invention provides a continuous purification system for glycine, wherein the inlet pipe of hexamethylenetetramine solution is connected to the outlet pipe of the mother liquor, and the mother liquor is returned to the first-stage reactor for reuse.

[0018] IV. The present invention provides a continuous purification system for glycine, wherein the feed valve and flow meter enable precise feeding of mother liquor, methanol solution, hexamethylenetetramine solution, chloroacetic acid solution and ammonia. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the structure of Embodiment 2 of this utility model; The components are as follows: 1. Reaction liquid inlet pipe; 2. First low-temperature crystallization kettle; 3. Second low-temperature crystallization kettle; 4. First connecting pipe; 5. First centrifuge; 6. Second connecting pipe; 7. First discharge pipe; 8. Mother liquor discharge pipe; 9. Pulping kettle; 10. Third connecting pipe; 11. Methanol solution inlet pipe; 12. Second centrifuge; 13. Second discharge pipe; 14. Methanol mother liquor discharge pipe; 15. Flash tank; 16. Gas phase discharge pipe; 17. Ammonium chloride concentrated solution discharge pipe; 18. Condenser. 19. Methanol solution inlet pipe; 20. First-stage reactor; 21. Second-stage reactor; 22. Hexamethylenetetramine solution inlet pipe; 23. Chloroacetic acid solution inlet pipe; 24. First ammonia inlet pipe; 25. First tail gas outlet pipe; 26. Feed pipe; 27. Second ammonia inlet pipe; 28. Second tail gas outlet pipe; 30. First reaction liquid branch pipe; 31. Second reaction liquid branch pipe; 32. Temperature sensor; 33. Stirring device; 34. Feed valve; 35. Flow meter. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0021] Example 1 like Figure 1As shown, a continuous purification system for glycine includes a reaction liquid inlet pipe 1, which is connected to a first low-temperature crystallization vessel 2 and a second low-temperature crystallization vessel 3. The first low-temperature crystallization vessel 2 is connected to a first centrifuge 5 via a first connecting pipe 4, and the second low-temperature crystallization vessel 3 is connected to the first centrifuge 5 via a second connecting pipe 6. The centrifuge is equipped with a first discharge pipe 7 and a mother liquor discharge pipe 8. The first discharge pipe 7 is connected to a pulping vessel 9. The pulping vessel 9 is equipped with a third connecting pipe 10 and a methanol solution inlet pipe 11. The third connecting pipe 10 is connected to a second centrifuge 12. The second centrifuge 12 is equipped with a second discharge pipe 13 and a methanol mother liquor discharge pipe 14. The methanol mother liquor discharge pipe 14 is connected to a flash tank 15. The flash tank 15 is connected to a gas phase outlet pipe 16 and an ammonium chloride concentrate outlet pipe 17. The gas phase outlet pipe 16 is connected to the methanol solution inlet pipe 11 via a condenser 18.

[0022] Example 2 like Figure 2 As shown, a continuous purification system for glycine includes a reaction liquid inlet pipe 1, which is connected to a first low-temperature crystallization vessel 2 and a second low-temperature crystallization vessel 3. The first low-temperature crystallization vessel 2 is connected to a first centrifuge 5 via a first connecting pipe 4, and the second low-temperature crystallization vessel 3 is connected to the first centrifuge 5 via a second connecting pipe 6. The centrifuge is equipped with a first discharge pipe 7 and a mother liquor discharge pipe 8. The first discharge pipe 7 is connected to a pulping vessel 9. The pulping vessel 9 is equipped with a third connecting pipe 10 and a methanol solution inlet pipe 11. The third connecting pipe 10 is connected to a second centrifuge 12. The second centrifuge 12 is equipped with a second discharge pipe 13 and a methanol mother liquor discharge pipe 14. The methanol mother liquor discharge pipe 14 is connected to a flash tank 15. The flash tank 15 is connected to a gas phase outlet pipe 16 and an ammonium chloride concentrate outlet pipe 17. The gas phase outlet pipe 16 is connected to the methanol solution inlet pipe 11 via a condenser 18.

[0023] The reaction liquid inlet pipe 1 is connected to the glycine reaction system.

[0024] The glycine reaction system includes a first-stage reactor 20 and a second-stage reactor 21. The first-stage reactor 20 is equipped with a hexamethylenetetramine solution inlet pipe 22, a chloroacetic acid solution inlet pipe 23, a first ammonia gas inlet pipe 24, a first tail gas outlet pipe 25, and a feed pipe 26. The first-stage reactor 20 is connected to the second-stage reactor 21 through the feed pipe 26. The second-stage reactor 21 is equipped with a second ammonia gas inlet pipe 27, a second tail gas outlet pipe 28, and a reaction liquid inlet pipe 1.

[0025] The reaction liquid inlet pipe 1 is connected to the first reaction liquid branch pipe 30 and the second reaction liquid branch pipe 31, and the first reaction liquid branch pipe 30 and the second reaction liquid branch pipe 31 are respectively connected to the first low-temperature crystallization vessel 2 and the second low-temperature crystallization vessel 3.

[0026] The hexamethylenetetramine solution inlet pipe 22 is connected to the mother liquor outlet pipe 8.

[0027] Temperature sensors 32 are installed on the first-stage reactor 20, the second-stage reactor 21, the first low-temperature crystallization reactor 2, the second low-temperature crystallization reactor 3, and the pulping reactor 9.

[0028] Among them, the first-stage reactor 20, the second-stage reactor 21, the first low-temperature crystallization reactor 2, the second low-temperature crystallization reactor 3, and the pulping reactor 9 are all equipped with stirring devices 33.

[0029] Among them, the first connecting pipe 4, the second connecting pipe 6, the mother liquor outlet pipe 8, the first discharge pipe 7, the third connecting pipe 10, the methanol solution inlet pipe 11, the second discharge pipe 13, the methanol mother liquor outlet pipe 14, the gas phase outlet pipe 16, the ammonium chloride concentrated solution outlet pipe 17, the hexamethylenetetramine solution inlet pipe 22, the chloroacetic acid solution inlet pipe 23, the first ammonia gas inlet pipe 24, the first tail gas outlet pipe 25, the feed pipe 26, the first reaction liquid branch pipe 30, and the second reaction liquid branch pipe 31 are all equipped with feed valves 34.

[0030] Flow meters 35 are installed on the mother liquor outlet pipe 8, methanol solution inlet pipe 11, hexamethylenetetramine solution inlet pipe 22, chloroacetic acid solution inlet pipe 23, first ammonia inlet pipe 24 and second ammonia inlet pipe 27.

[0031] Among them, the first low-temperature crystallization vessel 2, the second low-temperature crystallization vessel 3, the first centrifuge 5, the pulping vessel 9, the second centrifuge 12, the flash tank 15, the condenser 18, the first-stage reaction vessel 20, the second-stage reaction vessel 21, the temperature sensor 32, the stirring device 33, the feed valve 34, and the flow meter 35 are all existing technologies and will not be described in detail here.

[0032] The beneficial effects of this technical solution are as follows: I. This utility model provides a continuous purification system for glycine. The glycine reaction solution enters a first low-temperature crystallization vessel 2 or a second low-temperature crystallization vessel 3 through a reaction solution inlet pipe 1. The glycine reaction solution undergoes cooling and crystallization in the first low-temperature crystallization vessel 2 or the second low-temperature crystallization vessel 3. After crystallization, it enters a first centrifuge 5 through a first connecting pipe 4 or a second connecting pipe 6 for the first centrifuge treatment. The first centrifuge yields a mother liquor (containing glycine, ammonium chloride, hexamethylenetetramine, and other impurities) and a first wet product. The first wet product (containing ammonium chloride, glycine, and a small amount of mother liquor) is discharged into a pulping vessel 9 through a first discharge pipe 7. The mother liquor can be reused. A methanol solution is passed through the pulping vessel 9. Methanol solution is added to inlet pipe 11 and fully dissolved to obtain a solution. The solution flows into the second centrifuge 12 through the third connecting pipe 10 for a second centrifugation. The second centrifugation yields methanol mother liquor and a second wet product. The second wet product (which includes glycine and a small amount of methanol mother liquor) is discharged through the second discharge pipe 13 and then dried to obtain the glycine product. The methanol mother liquor is discharged into the flash tank 15 through the methanol mother liquor outlet pipe 14 for flash evaporation to obtain methanol gas and ammonium chloride concentrate. The methanol gas enters the condenser 18 through the gas phase outlet pipe 16 and is condensed to obtain a methanol solution, which flows into the pulping tank 9 through the methanol solution inlet pipe 11. The ammonium chloride concentrate is discharged through the ammonium chloride concentrate outlet pipe 17 and dried to obtain ammonium chloride.

[0033] II. The present invention provides a continuous purification system for glycine. Urotropine solution, chloroacetic acid solution and ammonia gas are introduced into the first-stage reactor 20 through the urotropine solution inlet pipe 22, the chloroacetic acid solution inlet pipe 23 and the first ammonia gas inlet pipe 24 respectively to carry out the first-stage reaction. After the first-stage reaction is completed, the mixture is introduced into the second-stage reactor 21 through the second ammonia gas inlet pipe 27 to carry out the second-stage reaction to obtain the glycine reaction solution (including urotropine, glycine and ammonium chloride, etc.).

[0034] III. The present invention provides a continuous purification system for glycine, wherein the hexamethylenetetramine solution inlet pipe 22 is connected to the mother liquor outlet pipe 8, and the mother liquor is returned to the first-stage reactor 20 for reuse.

[0035] IV. The present invention provides a continuous purification system for glycine, wherein the feed valve 34 and the flow meter 35 enable precise feeding of mother liquor, methanol solution, hexamethylenetetramine solution, chloroacetic acid solution and ammonia.

[0036] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A system for the continuous purification of glycine, characterized in that: The system includes a reaction liquid inlet pipe (1), which is connected to a first low-temperature crystallization vessel (2) and a second low-temperature crystallization vessel (3). The first low-temperature crystallization vessel (2) is connected to a first centrifuge (5) via a first connecting pipe (4), and the second low-temperature crystallization vessel (3) is connected to the first centrifuge (5) via a second connecting pipe (6). The centrifuge is equipped with a first discharge pipe (7) and a mother liquor discharge pipe (8). The first discharge pipe (7) is connected to a pulping vessel (9), which is equipped with... There is a third connecting pipe (10) and a methanol solution inlet pipe (11). The third connecting pipe (10) is connected to a second centrifuge (12). The second centrifuge (12) is equipped with a second discharge pipe (13) and a methanol mother liquor outlet pipe (14). The methanol mother liquor outlet pipe (14) is connected to a flash tank (15). The flash tank (15) is connected to a gas phase outlet pipe (16) and an ammonium chloride concentrate outlet pipe (17). The gas phase outlet pipe (16) is connected to the methanol solution inlet pipe (11) through a condenser (18).

2. The system for continuous purification of glycine according to claim 1, characterized in that: The reaction liquid inlet pipe (1) is connected to the glycine reaction system.

3. The system for continuous purification of glycine according to claim 2, characterized in that: The glycine reaction system includes a first-stage reactor (20) and a second-stage reactor (21). The first-stage reactor (20) is equipped with a hexamethylenetetramine solution inlet pipe (22), a chloroacetic acid solution inlet pipe (23), a first ammonia inlet pipe (24), a first tail gas outlet pipe (25), and a feed pipe (26). The first-stage reactor (20) is connected to the second-stage reactor (21) through the feed pipe (26). The second-stage reactor (21) is equipped with a second ammonia inlet pipe (27), a second tail gas outlet pipe (28), and a reaction liquid inlet pipe (1).

4. The system for continuous purification of glycine according to claim 3, characterized in that: The reaction liquid inlet pipe (1) is connected to the first reaction liquid branch pipe (30) and the second reaction liquid branch pipe (31), and the first reaction liquid branch pipe (30) and the second reaction liquid branch pipe (31) are respectively connected to the first low temperature crystallization vessel (2) and the second low temperature crystallization vessel (3).

5. The system for continuous purification of glycine according to claim 4, characterized in that: The hexamethylenetetramine solution inlet pipe (22) is connected to the mother liquor outlet pipe (8).

6. The system for continuous purification of glycine according to claim 5, characterized in that: Temperature sensors (32) are installed on the first stage reactor (20), the second stage reactor (21), the first low-temperature crystallization reactor (2), the second low-temperature crystallization reactor (3), and the pulping reactor (9).

7. The system for continuous purification of glycine according to claim 6, characterized in that: A stirring device (33) is provided on the first stage reactor (20), the second stage reactor (21), the first low temperature crystallization reactor (2), the second low temperature crystallization reactor (3) and the pulping reactor (9).

8. The system for continuous purification of glycine according to claim 7, characterized in that: A feed valve (34) is provided on the first connecting pipe (4), the second connecting pipe (6), the mother liquor outlet pipe (8), the first discharge pipe (7), the third connecting pipe (10), the methanol solution inlet pipe (11), the second discharge pipe (13), the methanol mother liquor outlet pipe (14), the gas phase outlet pipe (16), the ammonium chloride concentrated solution outlet pipe (17), the hexamethylenetetramine solution inlet pipe (22), the chloroacetic acid solution inlet pipe (23), the first ammonia gas inlet pipe (24), the first tail gas outlet pipe (25), the feed pipe (26), the first reaction liquid branch pipe (30), and the second reaction liquid branch pipe (31).

9. The system for continuous purification of glycine according to claim 8, characterized in that: Flow meters (35) are installed on the mother liquor outlet pipe (8), methanol solution inlet pipe (11), hexamethylenetetramine solution inlet pipe (22), chloroacetic acid solution inlet pipe (23), first ammonia inlet pipe (24) and second ammonia inlet pipe (27).

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