A double-effect evaporation water circulation utilization system and a glycine production line
By designing a dual-effect evaporated water recycling system, evaporated water is used for glycine reaction hydration and pH regulation, the problem of large amount of wastewater in glycine production is solved and the efficient utilization of resources is achieved.
Patent Information
- Application Number
- CN202310239166.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-14
- Publication Date
- 2025-05-27
- Estimated Expiration
- 2043-03-14
AI Technical Summary
During the production of glycine, the raw materials contain a large amount of water and need to be replenished during the reaction process, resulting in a large amount of industrial wastewater generated in the dual-effect evaporation stage, which makes it difficult to deal with the problem.
A dual-effect evaporation water recycling system is designed, and the first-effect evaporation water is used for glycine reaction water replenishment and solid ulotropine with water dissolution, and the second-effect evaporation water is used for pH and alkalinity and temperature regulation to form a recycling circuit.
It reduces the amount of wastewater in the glycine production process, reduces production water consumption, and improves resource utilization efficiency.
Smart Images
Figure CN116161728B_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of chemical production, and particularly relates to a double-effect evaporation water recycling system and a glycine production line. Background Art
[0002] Chloroacetic acid and liquid ammonia react under the catalysis of hexamine to form a mixed solution of glycine and ammonium chloride. The mixed solution is subjected to methanol crystallization extraction to obtain finished glycine and mother liquor containing ammonium chloride. The mother liquor is subjected to methanol rectification to recover methanol, and the residual liquid after methanol rectification is concentrated and crystallized by double-effect evaporation to obtain ammonium chloride after removing water.
[0003] Among the raw materials in the glycine reaction stage, the 81.5% aqueous solution of chloroacetic acid and the 25% aqueous solution of hexamine contain a large amount of water, and make-up water needs to be added before and after the reaction to flush the pipeline and products. This makes the mother liquor after extraction contain a large amount of water, resulting in a large amount of industrial wastewater generated in the double-effect evaporation stage. The treatment of double-effect evaporation water has always been a difficult problem in the industry. Summary of the Invention
[0004] The present application provides a double-effect evaporation water recycling system and a glycine production line, which use the first-effect evaporation water for make-up water in glycine reaction and for dissolving solid hexamine in water, and use the second-effect evaporation water for pH and temperature adjustment, reducing the amount of wastewater in the glycine production process and also reducing the production water consumption.
[0005] The above object of the present application is achieved through the following technical solutions:
[0006] In a first aspect, the present application provides a double-effect evaporation water recycling system, including:
[0007] A double-effect evaporator, having one input end and two output ends;
[0008] A first temporary storage tank, connected to the first output end of the double-effect evaporator;
[0009] A second temporary storage tank, connected to the second output end of the double-effect evaporator;
[0010] A circulation pipeline, communicating with the space inside the reaction kettle and forming a loop;
[0011] A circulation pump, provided on the circulation pipeline;
[0012] A first temperature sensor and a pH sensor, both provided on the circulation pipeline;
[0013] A first feeding pump, connected to the first temporary storage tank and the reaction kettle;
[0014] A second feeding pump, connected to the second temporary storage tank and the reaction kettle; and
[0015] A controller, configured to drive a second feed pump according to the feedback of a temperature sensor and a pH sensor to adjust the temperature and pH value in the reactor.
[0016] In a possible implementation of the first aspect, it further includes a second temperature sensor provided on the first temporary storage tank, and the second temperature sensor is configured to feed back the temperature of the evaporated water in the first temporary storage tank to the controller.
[0017] In a possible implementation of the first aspect, it further includes a third temperature sensor provided on the second temporary storage tank, and the third temperature sensor is configured to feed back the temperature of the evaporated water in the second temporary storage tank to the controller.
[0018] In a possible implementation of the first aspect, the space in the first temporary storage tank is divided into a high-temperature area and a low-temperature area;
[0019] It further includes a heat exchanger connected to the low-temperature area, and the heat exchanger is used to reduce the temperature of the evaporated water in the low-temperature area.
[0020] In a possible implementation of the first aspect, the heat exchanger and the double-effect evaporator form a loop.
[0021] In a possible implementation of the first aspect, the second temporary storage tank is further connected to the water preparation process of chloroacetic acid solution and the tail gas absorption process of chloroacetic acid reaction.
[0022] In a possible implementation of the first aspect, it further includes:
[0023] A flushing pump, connected to the reactor and the second temporary storage tank; and
[0024] A flushing pipeline, connected to the reactor and the first temporary storage tank.
[0025] In a possible implementation of the first aspect, the flushing pipeline is connected to the low-temperature area in the first temporary storage tank.
[0026] In a second aspect, the present application provides a glycine production line, including the double-effect evaporation water recycling system as described in the first aspect and any implementation of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 is a schematic diagram of the principle of a double-effect evaporation water recycling system provided by the present application.
[0028] Figure 2 is a schematic diagram of the solution flow direction in a recycling pipeline provided by the present application.
[0029] Figure 3 is a schematic diagram of the division of the high-temperature area and the low-temperature area provided by the present application.
[0030] Figure 4 It is another schematic diagram of the division of the high-temperature zone and the low-temperature zone provided by this application.
[0031] Figure 5 It is a schematic diagram of the principle of another double-effect evaporation water circulation utilization system provided by this application.
[0032] Figure 6 It is a schematic diagram of the principle of yet another double-effect evaporation water circulation utilization system provided by this application.
[0033] In the figure, 11 is a double-effect evaporator, 12 is a first temporary storage tank, 13 is a second temporary storage tank, 14 is a heat exchanger, 21 is a circulation pipeline, 22 is a circulation pump, 23 is a first temperature sensor, 24 is a pH value sensor, 25 is a second temperature sensor, 26 is a third temperature sensor, 31 is a first feeding pump, 32 is a second feeding pump, 41 is a flushing pump, 42 is a flushing pipeline, 6 is a controller, 121 is a high-temperature zone, and 122 is a low-temperature zone. Embodiment
[0034] The technical solutions in this application will be further described in detail below with reference to the accompanying drawings.
[0035] To understand the technical solution more clearly, first briefly describe the production process of glycine: chloroacetic acid and liquid ammonia react under the catalysis of hexamine to form a mixed solution of glycine and ammonium chloride. The mixed solution is crystallized and extracted with methanol to obtain finished glycine and mother liquor containing ammonium chloride. The mother liquor is rectified with methanol to recover methanol, and the residue after methanol rectification is concentrated and crystallized by double-effect evaporation to obtain ammonium chloride after removing water.
[0036] Among the raw materials in the glycine reaction stage, the 81.5% aqueous chloroacetic acid solution and the 25% aqueous hexamine solution contain a large amount of water, and additional water needs to be added before and after the reaction to flush the pipelines and products. This makes the mother liquor after extraction contain a large amount of water.
[0037] Specifically, water is required for the preparation process of the chloroacetic acid aqueous solution, water is required for the dissolution of hexamine, the condensates on the inner walls of the equipment during the production process need to be cleaned with water, and the finished products need to be rinsed with water. The water in the above processes will all be collected in the mother liquor.
[0038] Please refer to Figure 1 , which is a double-effect evaporation water circulation utilization system disclosed in this application. The system consists of a double-effect evaporator 11, a first temporary storage tank 12, a second temporary storage tank 13, a circulation pipeline 21, a circulation pump 22, a first temperature sensor 23, a pH value sensor 24, a first feeding pump 31, a second feeding pump 32, a controller 6, etc.
[0039] The double-effect evaporator 11 has an input end and two output ends. The input end of the double-effect evaporator 11 is connected to the mother liquor tank, and the two output ends are respectively connected to the first temporary storage tank 12 and the second temporary storage tank 13. The first-effect evaporated water output by the double-effect evaporator 11 flows into the first temporary storage tank 12 for temporary storage, and the second-effect evaporated water output by the double-effect evaporator 11 flows into the second temporary storage tank 13 for temporary storage.
[0040] Please refer to Figure 2 , the circulation pipeline 21 is connected to the space inside the reaction kettle and forms a loop. That is to say, the substances in the reaction kettle can enter the circulation pipeline 21. The circulation pump 22 is installed on the circulation pipeline 21, and its function is to drive the flow of substances in the circulation pipeline 21. The purpose of this design is to obtain more accurate temperature and pH value inside the reaction kettle. Because the solution in the circulation pipeline 21 circulates, the detection ranges of the first temperature sensor 23 and the pH sensor 24 can be expanded, and the detected values are also more accurate.
[0041] The first temperature sensor 23 and the pH sensor 24 are both installed on the circulation pipeline 21, and their functions are to detect the temperature and pH value of the substances in the reaction kettle. The first feeding pump 31 is connected to the first temporary storage tank 12 and the reaction kettle, and its function is to send the first-effect evaporated water in the first temporary storage tank 12 into the reaction kettle. The second feeding pump 32 is connected to the second temporary storage tank 13 and the reaction kettle, and its function is to send the second-effect evaporated water in the second temporary storage tank 13 into the reaction kettle.
[0042] It should be understood that the first-effect evaporated water has a high temperature and a high ammonia content, and can be used for water replenishment in glycine reaction and dissolution of solid hexamine in water. The second-effect evaporated water has a low temperature and a low ammonia content, and can be used for pH value and temperature adjustment.
[0043] The specific process is to first dissolve a certain amount of hexamine with the first-effect evaporated water. The reason for using the first-effect evaporated water to dissolve hexamine here is that the first-effect evaporated water has a high temperature, which can accelerate the dissolution rate of hexamine. At the same time, it can also make the temperature of the hexamine solution high, and can reduce the heating time of the reaction kettle.
[0044] After the dissolution of hexamine is completed, then dropwise add chloroacetic acid solution and introduce liquid ammonia. The chemical reaction formula for the reaction of chloroacetic acid and liquid ammonia to produce glycine and ammonium chloride under the catalysis of hexamine is as follows:
[0045] ClCH2COOH + 2NH3 → H2NCH2COOH + NH4Cl
[0046] This reaction process is an exothermic process, and a large amount of heat will be generated during the reaction process. According to the principle of chemical reaction equilibrium, lowering the temperature is beneficial to the formation of aminoacetic acid. The reaction temperature during the production process is controlled at about 70°.
[0047] The purpose of replenishing water for the first-effect evaporated water is to keep the amount of solution in the reaction kettle stable. Because during the reaction process, there will be a certain amount of water consumption. The temperature of the first-effect evaporated water is high and can be used for replenishing water in the glycine reaction. Except for replenishing water and dissolving hexamine, clear water is used in other processes.
[0048] The reaction temperature during the glycine reaction is controlled at about 70 °C. The reason is that low temperature will lead to slow reaction speed, incomplete reaction and long production cycle, while high temperature will lead to too intense reaction and increased side reactions. The pH value (acidity and alkalinity) during the glycine reaction should be controlled at 7.0 - 7.5. When the pH value < 6, it will lead to an increase in the iron content of the product and incomplete reaction. When the pH value > 9, it will lead to too fine particles of the product, increased loss during filtration and washing, and at the same time, the escape caused by too much ammonia content will pollute the environment and cause waste.
[0049] The temperature of the second-effect evaporated water is low and can be used for rapid cooling of the solution in the reaction kettle. And because the second-effect evaporated water contains a certain amount of hydrochloric acid, it can also be used for adjusting the pH value of the solution in the reaction kettle, so that the pH value (acidity and alkalinity) during the reaction process is stable at 7.0 - 7.5.
[0050] In addition, the first-effect evaporated water can also be used for adjusting the temperature of the solution in the reaction kettle. When the temperature in the reaction kettle drops, a certain amount of the first-effect evaporated water can be quickly injected into the reaction kettle to make the temperature of the solution in the reaction kettle rise.
[0051] Please refer to Figure 1 , the above process is executed by the controller 6. The controller 6 is electrically connected to the first temperature sensor 23, pH value sensor 24, first feed pump 31 and second feed pump 32 and drives the first temperature sensor 23, pH value sensor 24, first feed pump 31 and second feed pump 32 to perform corresponding actions according to the above content.
[0052] Please refer to Figure 1 , as a specific implementation manner of the double-effect evaporation water recycling system provided by the application, a second temperature sensor 25 is added to the first temporary storage tank 12. The second temperature sensor 25 is configured to feedback the temperature of the evaporated water in the first temporary storage tank 12 to the controller 6. The second temperature sensor 25 realizes the dynamic temperature monitoring of the first-effect evaporated water in the first temporary storage tank 12 and can adjust more accurately during the temperature adjustment process of the solution in the reaction kettle.
[0053] Please refer to Figure 1 , further, a third temperature sensor 26 is installed on the second temporary storage tank 13. The third temperature sensor 26 is configured to feedback the temperature of the evaporated water in the second temporary storage tank 13 to the controller 6.
[0054] Please refer to Figure 3 and Figure 4, as a specific implementation of the dual-effect evaporation water circulation utilization system provided by the application, the space in the first temporary storage tank 12 is divided into a high-temperature area 121 and a low-temperature area 122, and the temperature of the first-effect evaporation water stored in the high-temperature area 121 is higher than that of the first-effect evaporation water stored in the low-temperature area 122.
[0055] After the high-temperature area 121 and the low-temperature area 122 appear, it is necessary to monitor their temperatures respectively and form loops with the reaction kettle using pipelines respectively.
[0056] The low-temperature area 122 is connected to the heat exchanger 14, and the heat exchanger 14 is used to reduce the temperature of the evaporation water in the low-temperature area 122. In some possible implementation manners, the heat exchanger 14 and the dual-effect evaporator 11 form a loop.
[0057] The first-effect evaporation water stored in the low-temperature area 122 is used to adjust the pH value in the reaction kettle. For example, the temperature of the first-effect evaporation water stored in the low-temperature area 122 is kept consistent with the temperature of the solution in the reaction kettle. In this way, when the pH value of the solution in the reaction kettle is greater than 7.0 - 7.5, a certain amount of the first-effect evaporation water in the low-temperature area 122 can be injected into the reaction kettle to realize the decrease of the pH value of the solution in the reaction kettle.
[0058] , as a specific implementation of the dual-effect evaporation water circulation utilization system provided by the application, the second-effect evaporation water stored in the second temporary storage tank 13 is also connected to the water preparation process of chloroacetic acid solution and the absorption process of chloroacetic acid reaction tail gas. After the fresh water used in these two processes is replaced by the second-effect evaporation water, the water consumption in the production process can be further reduced.
[0059] Please refer to Figure 5 , as a specific implementation of the dual-effect evaporation water circulation utilization system provided by the application, a flushing pump 41 and a flushing pipeline 42 are also added. The flushing pump 41 is connected to the reaction kettle and the second temporary storage tank 13, and the flushing pipeline 42 is connected to the reaction kettle and the first temporary storage tank 12.
[0060] When flushing the reaction kettle and the pipeline, the second-effect evaporation water is used for flushing. After the flushing is completed, the second-effect evaporation water enters the first temporary storage tank 12 for storage. It should be understood that after each discharging, a layer of white glycine crystals will appear on the inner walls of the reaction kettle and the pipeline. This layer of crystals will affect heat transfer and also cause waste. Therefore, it is necessary to flush the reaction kettle and the pipeline. After flushing, this layer of white glycine crystals will flow into the first temporary storage tank 12 for storage, and then be added to the reaction kettle during subsequent use.
[0061] Please refer to Figure 6, Further, the flushing pipeline 42 is connected to the low-temperature area 122 in the first temporary storage tank 12, so that the evaporated water with glycine crystals can flow into the low-temperature area 122 for storage. The temperature of the evaporated water in the low-temperature area 122 is low, which is beneficial to the stability of glycine crystals (they will not be dissolved by high temperature).
[0062] In addition, the evaporated water (with glycine crystals) stored in the low-temperature area 122 can also be injected into the reaction kettle after the reaction in the reaction kettle is completed. On the one hand, it can reduce the temperature of the solution in the reaction kettle, and on the other hand, it can use these glycine crystals as crystal seeds, so that glycine in the solution in the reaction kettle can aggregate on the surface of the crystal seeds at a faster speed. The crystal particles obtained in this way are large, have high purity, uniform particle size, and are easy to filter and wash.
[0063] This application also discloses a glycine production line, including any one of the double-effect evaporation water circulation utilization systems described above.
[0064] The embodiments of this specific implementation manner are all preferred embodiments of this application, and do not limit the protection scope of this application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.
Claims
1. A double-effect evaporation water circulation utilization system, characterized in that, it includes: A double-effect evaporator (11) having an input end and two output ends; A first temporary storage tank (12) connected to the first output end of the double-effect evaporator (11), and the first-effect evaporated water in the first temporary storage tank (12) is used for water replenishment in glycine reaction and water dissolution for solid hexamine; A second temporary storage tank (13) connected to the second output end of the double-effect evaporator (11), and the second-effect evaporated water in the second temporary storage tank (13) is used for pH and temperature adjustment; A circulation pipeline (21) communicating with the space inside the reaction kettle to form a loop; A circulation pump (22) provided on the circulation pipeline (21); A first temperature sensor (23) and a pH sensor (24), both provided on the circulation pipeline (21); A first feeding pump (31) connected to the first temporary storage tank (12) and the reaction kettle; A second feeding pump (32) connected to the second temporary storage tank (13) and the reaction kettle; and A controller (6) configured to drive the second feeding pump (32) according to the feedback of the first temperature sensor (23) and the pH sensor (24) to adjust the temperature and pH value inside the reaction kettle.
2. The double-effect evaporation water circulation utilization system according to claim 1, characterized in that, it further includes a second temperature sensor (25) provided on the first temporary storage tank (12), and the second temperature sensor (25) is configured to feedback the temperature of the evaporated water inside the first temporary storage tank (12) to the controller (6).
3. The double-effect evaporation water circulation utilization system according to claim 1 or 2, characterized in that, it further includes a third temperature sensor (26) provided on the second temporary storage tank (13), and the third temperature sensor (26) is configured to feedback the temperature of the evaporated water inside the second temporary storage tank (13) to the controller (6).
4. The double-effect evaporation water circulation utilization system according to claim 1, characterized in that, the space inside the first temporary storage tank (12) is divided into a high-temperature area (121) and a low-temperature area (122); it further includes a heat exchanger (14) connected to the low-temperature area (122), and the heat exchanger (14) is used to reduce the temperature of the evaporated water inside the low-temperature area (122).
5. The double-effect evaporation water circulation utilization system according to claim 4, characterized in that, the heat exchanger (14) and the double-effect evaporator (11) form a loop.
6. The double-effect evaporation water circulation utilization system according to claim 1, characterized in that, the second temporary storage tank (13) is further connected to the water preparation process for chloroacetic acid solution and the tail gas absorption process for chloroacetic acid reaction.
7. The double-effect evaporation water circulation utilization system according to claim 4, characterized in that, it further includes: A flushing pump (41) connected to the reaction kettle and the second temporary storage tank (13); and A flushing pipeline (42) connected to the reaction kettle and the first temporary storage tank (12).
8. The double-effect evaporation water circulation utilization system according to claim 7, characterized in that, the flushing pipeline (42) is connected to the low-temperature area (122) inside the first temporary storage tank (12).
9. A glycine production line, characterized in that, it includes the double-effect evaporation water circulation utilization system according to any one of claims 1 to 8.
Citation Information
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