Production method of glycine mixed crystal intermediate

Abstract

The present invention discloses a glycine mixed crystal intermediate production method, and relates to the technical field of glycine production, the method comprises the following specific steps: raw material mixing and heating reaction: crushed solid chloroacetic acid, crushed liquid chloroacetic acid and recovered mother liquor are added into a continuous reaction kettle together, in the continuous reaction kettle, a reaction is performed for 2-4 h, the reaction temperature of the neutralization reaction stage is controlled in a low-temperature reaction zone, and after the neutralization reaction is completed, the reaction stage of generating glycine is entered. In the crystallization process, glycine and ammonium chloride are naturally saturated and separated out in the mother liquor to generate an intermediate, so that the operation steps and the use amount of methanol are reduced, and the crystallization process is continuously completed; meanwhile, the loss of urotropin in the reaction mother liquor is extremely small, the mother liquor can be recycled, and the mixture is put into the reaction kettle again after being mixed with new solid chloroacetic acid or liquid chloroacetic acid, so that the recovery rate of glycine is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of glycine production, in particular to a method for producing a glycine mixed crystal intermediate. Background Art

[0002] Glycine, as an important chemical raw material and pharmaceutical intermediate, is widely used in many fields such as food, feed, and medicine. With the continuous growth of market demand, higher requirements are placed on the efficiency, environmental protection and product quality of glycine production processes. At present, glycine production technologies are showing a diversified trend, and different processes have their own advantages and disadvantages in terms of cost, efficiency and environmental impact. Against this background, optimizing glycine production processes and improving production efficiency and product quality have become key issues that need to be urgently addressed in the industry, which is of great significance to promoting the sustainable development of the glycine industry.

[0003] The main traditional process for glycine production uses the chloroacetic acid ammonolysis method. However, this process has many serious drawbacks. In terms of energy consumption, the separation process accounts for up to 80% of the total production process energy consumption, greatly increasing production costs and reducing the company's economic benefits. In terms of product quality, due to the difficulty in completely separating ammonium chloride in the reaction system, residual ammonium chloride is easily retained in the product. This not only affects the product purity but also makes it difficult to improve the product quality grade, limiting the product's application in high-end fields. Yield is also a prominent issue. Repeated recrystallization operations cause some product to be lost with the mother liquor, resulting in low raw material utilization and reduced overall production efficiency. In addition, this process causes serious raw material waste and environmental pollution. The direct discharge of the mother liquor not only wastes valuable raw materials such as hexamine, glycine, and ammonium chloride, but also generates a large amount of wastewater, placing tremendous pressure on the ecological environment. These problems have seriously restricted the further application and development of the traditional chloroacetic acid ammonolysis method in glycine production. A new production process is urgently needed to solve these problems. Summary of the Invention

[0004] The object of the present invention is to overcome the deficiencies of the prior art and provide a method for producing a glycine mixed crystal intermediate. The method can ensure efficient and stable reaction by selecting a reactor made of specific materials and equipped with advanced equipment during the raw material mixing and temperature reaction stage, accurately controlling parameters such as reaction temperature, stirring speed, pressure, and concentration of each component. In the ammonium chloride crystallization and precipitation step, the principle of natural saturation precipitation of glycine and ammonium chloride in the mother liquor is utilized to form a special and uniform crystal form by controlling the temperature and stirring speed of the crystallization kettle, thereby facilitating subsequent separation. An efficient continuous centrifuge is used in the centrifugation and washing stages to accurately control the centrifugation and washing parameters and improve product quality. High-temperature nitrogen circulation drying is used in the drying and collection stages to reduce energy consumption and environmental pollution. The process realizes efficient and green production of glycine, has many beneficial effects such as obvious crystallization advantages, simplified process, reduced cost, efficient utilization of raw materials, efficient and environmentally friendly reaction, and improved product quality, thereby bringing new development opportunities to the glycine production industry.

[0005] In order to solve the above technical problems, the present invention provides the following technical solution: a method for producing a glycine mixed crystal intermediate, the method comprising the following specific steps: Raw material mixing and temperature reaction: The pulverized solid or liquid chloroacetic acid is added to a continuous reactor together with the recovered mother liquor. In the continuous reactor, the reaction temperature of the neutralization reaction stage is controlled within the low-temperature reaction zone. After the neutralization reaction is completed, the reaction stage of producing glycine is entered. Through continuous reactions in multiple reactors, the mixed solution reaches the temperature conditions required for subsequent production. Crystallization intermediate precipitation: After the reaction in the continuous reactor is completed, the mixed liquid flows into the continuous crystallization reactor. In the crystallization reactor, the intermediate with a special crystal form is formed by the principle that glycine and ammonium chloride naturally precipitate after reaching a saturated state in the mother liquor. After the crystallization process is completed, the mother liquor separated in the crystallization reactor is recovered and mixed with new solid chloroacetic acid or liquid chloroacetic acid, and then put into the reactor to continue the reaction; Centrifugation and washing: The mixed solution of the crystallization intermediate and mother liquor flowing out of the crystallization kettle outlet enters the continuous centrifuge, where it is continuously centrifuged and washed to remove impurities in the mixed crystal intermediate and obtain a granular product with a certain humidity; Drying and collection: After continuous centrifugation and washing, the granular products are transported to the drying pipe. In the drying pipe, the particles are dried by the flow of high-temperature nitrogen. During the drying process, the dried particles are collected by the bag dust collector. The cooled nitrogen is reheated by the blower and heat exchange device, turning it into high-temperature nitrogen again and continuing to circulate in the drying pipe.

[0006] Furthermore, in the raw material mixing and temperature reaction step, the crushed solid chloroacetic acid or liquid chloroacetic acid and the recovered mother liquor are added to the continuous reactor, the stirring device is turned on, and the stirring speed is adjusted to 30-150 r / min to fully mix the raw materials. In the neutralization reaction stage, the temperature in the reactor is controlled at 20° C. to 50° C. using a temperature control system, and the pH value of the reaction system is detected to be greater than 7 to determine whether the neutralization reaction is complete.

[0007] Furthermore, in the raw material mixing and temperature-raising reaction step, after the neutralization reaction is completed, the reaction stage of generating glycine is entered, the reaction temperature is maintained at 30°C-50°C, the insulation reaction temperature does not exceed 65°C, and the reaction time is controlled within 4 hours.

[0008] Furthermore, in the crystallization intermediate step, the mixed solution after the reaction in the continuous reactor is introduced into the crystallization kettle, the temperature is controlled at 30°C-50°C, no other materials are added to the crystallization kettle, and the glycine mixed solution and ammonium chloride are naturally precipitated to generate the intermediate after reaching saturation in the mother liquor. The temperature in the crystallization kettle is controlled to be maintained at 15°C-25°C for continuous crystallization.

[0009] Furthermore, in the centrifugation and washing steps, the crystalline intermediate and mother liquor mixture is transported to a continuous centrifuge through a pipeline, the centrifuge is turned on, the drum speed is adjusted to 900-4000 r / min, and solid-liquid separation is achieved under the action of centrifugal force. During the centrifugation process, methanol washing liquid is added to the centrifuge, and the mass ratio of the washing liquid to the crystalline intermediate is 0.1-1:1 for washing operation, and the mother liquor and washing liquid are collected and disposed of separately.

[0010] Furthermore, in the centrifugation and washing steps, the temperature of the washing liquid is controlled at 20°C-30°C during washing. After the centrifugation and washing are completed, a granular product with a moisture content between 2% and 10% is obtained.

[0011] Furthermore, in the drying and collection steps, a conveying device is used to deliver the granular product after continuous centrifugation and washing into the drying pipe, and high-temperature nitrogen is delivered to the drying pipe through the pipe, fully contacting with the granular product, and the particles are dried by using the heat of the high-temperature nitrogen. At the outlet of the drying pipe, a bag dust collector with a filtration accuracy of 0.1 μm is set to collect the dried particles. The cooled nitrogen flows out from the other end of the drying pipe and enters the blower and heat exchange device. Under the action of the blower, the nitrogen is compressed and reheated through the heat exchange device, and circulates into the drying pipe to participate in the subsequent drying process. The moisture content of the particles after drying is detected and controlled to be below 1%.

[0012] Furthermore, in the drying and collecting steps, the temperature of the high-temperature nitrogen is 100°C-150°C, and the flow rate is controlled at 1000-200000 m³ / h.

[0013] Compared with the prior art, this method for producing a glycine mixed crystal intermediate has the following beneficial effects: 1. The present invention utilizes the natural saturated precipitation of glycine and ammonium chloride in the mother liquor to generate an intermediate during the crystallization process, thereby reducing the number of operating steps and the amount of methanol used, allowing the crystallization process to be completed continuously and significantly shortening the production cycle. At the same time, the loss of hexamethylenetetramine in the reaction mother liquor is extremely small, and the mother liquor can be recycled and mixed with new solid chloroacetic acid or liquid chloroacetic acid before being re-added to the reactor, thereby improving the recovery rate of glycine.

[0014] Second, the present invention ensures efficient and stable reaction by precisely controlling the raw material mixing and temperature reaction parameters, with a reaction yield of up to 99.99%. During the crystallization intermediate precipitation step, a special and uniform crystal form is formed. The ammonium chloride in the intermediate can be dissolved in high-temperature methanol. The crystal form is conducive to drying treatment, facilitating subsequent separation, and producing ammonium chloride with a special crystal form, effectively improving product quality and added value. In addition, the process is simplified, the operating process and methanol usage are reduced, production costs and safety risks are reduced, raw material utilization is improved, and product competitiveness in the market is enhanced, bringing higher economic benefits to the enterprise.

[0015] Other advantages, objects and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art based on an examination of the following or may be learned from the practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0017] Figure 1 This is a process flow chart for a method for producing a glycine mixed crystal intermediate; Figure 2 The present invention is a flow chart of a method for producing a glycine mixed crystal intermediate. DETAILED DESCRIPTION

[0018] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments. Example

[0019] A 5m³ 316L stainless steel continuous reactor is used. The reactor is equipped with a high-precision temperature control system with an accuracy of up to ±0.5°C, which can accurately control the reaction temperature. The stirring speed range of the stirring device is 30-150r / min, which can be flexibly adjusted according to the reaction requirements to ensure that the raw materials are fully mixed; the pressure monitoring device has a monitoring accuracy of ±0.01MPa, which monitors the pressure of the reaction system in real time to ensure the safety of the reaction process. At the same time, the reactor is also equipped with a feed port, a discharge port and interfaces for various monitoring instruments to facilitate the addition of raw materials, the discharge of products and the monitoring of the reaction process.

[0020] After solid chloroacetic acid is crushed into an average particle size of less than 1 mm using a crusher, it is added to a continuous reactor with a mass ratio of 1:5 with the recovered mother liquor that has been filtered, tested for composition, and properly treated (supplemented with methenamine, etc.). The stirring device is turned on and the stirring speed is adjusted to 100 r / min to ensure that the solid chloroacetic acid and the mother liquor are fully mixed. During the neutralization reaction stage, the temperature in the reactor is accurately controlled at 40°C using a temperature control system. The pH value of the reaction system is detected in real time by a pH sensor installed in the reactor. When the pH value is greater than 7, the neutralization reaction is judged to be completed. After the neutralization reaction is completed, the reaction stage of generating glycine is entered. Figure 1 As shown, the reaction temperature is maintained at 45°C, and the insulation reaction temperature is strictly controlled not to exceed 60°C. The reaction time in this stage is 3 hours. During the reaction, the pressure monitoring device monitors the pressure of the reaction system in real time to maintain it at about 0.2 MPa. In addition, the concentration changes of various components in the reaction system are monitored in real time by online analysis equipment such as high-performance liquid chromatography. The reaction conditions, such as temperature and stirring speed, are fine-tuned according to the monitoring results to ensure that the reaction proceeds in the direction of producing glycine.

[0021] The mixed liquid that has reacted in the continuous reactor and cooled to 30°C-50°C is introduced into a continuous crystallization reactor with a jacket. The jacket of the crystallization reactor is connected to a circulating ethylene glycol aqueous solution system, which can accurately control the temperature in the crystallization reactor. The crystallization reactor is equipped with a stirring device, and the stirring speed is adjusted to 50r / min. Without adding additional materials, glycine and ammonium chloride are naturally precipitated to form an intermediate after reaching saturation in the mother liquor. During the crystallization process, the growth of the crystals is observed under a microscope to ensure that the crystals have a good crystal form and enable continuous crystallization. After the crystallization is completed, a plate and frame filter press is used to separate the mother liquor in the crystallization reactor from the ammonium chloride crystals and glycine mixture. The separated mother liquor is collected in a storage tank, waits to be mixed with liquid chloroacetic acid, and then is put into the reactor again for the next round of reaction.

[0022] A horizontal spiral unloading sedimentation filter centrifuge was selected. The drum speed of the centrifuge can be flexibly adjusted within the range of 0-3000r / min. In this operation, the drum speed was adjusted to 2000r / min. The ammonium chloride crystals and glycine mixture were transported to the centrifuge through a pipeline at a feed rate of 500L / h. Solid-liquid separation was achieved under the action of centrifugal force. During the centrifugation process, methanol washing liquid with a mass ratio of 1:1 to the mixed liquid was added to the centrifuge for washing. During washing, the washing liquid temperature was precisely controlled at 60°C through the temperature control system to improve the washing effect and remove impurities attached to the crystal surface. After centrifugation and washing, a granular product with a moisture content of about 10% was obtained, which was suitable for further drying treatment.

[0023] The drying pipeline is made of 316L stainless steel, with an inner diameter of 500mm and a length of 10m. It is equipped with a high-temperature nitrogen delivery device. The temperature of the nitrogen can be adjusted within the range of 100℃-150℃. In this operation, the nitrogen temperature is adjusted to 120℃ and the flow rate is controlled to 1500m³ / h. A screw conveyor is used to deliver the granular product after continuous centrifugation and washing into the drying pipeline. The high-temperature nitrogen is transported into the drying pipeline through the pipeline and fully contacts the granular product. The heat of the high-temperature nitrogen is used to dry the particles. At the outlet of the drying pipeline, a A bag dust collector with a filtration accuracy of 0.1μm is installed to collect the dried particles. The cooled nitrogen flows out from the other end of the drying pipe and enters the blower and heat exchanger. Under the action of the blower, the nitrogen is compressed and reheated to 120°C through the heat exchanger, becoming high-temperature nitrogen again. It circulates into the drying pipe to participate in the subsequent drying process. The ammonium chloride in the final glycine mixed crystal intermediate is soluble in high-temperature methanol, and the product yield reaches 99.9%. The chloride ion content meets the high-quality product standards and meets the market quality requirements for glycine products. Example

[0024] A multi-stage series-connected 316L stainless steel continuous reactor is selected, with each reactor having a volume of 5m³, to form a continuous reaction system. Each reactor is equipped with a high-precision temperature control system, which can achieve precise temperature control of ±0.5°C. The stirring device has a variable frequency speed regulation function, and the stirring speed can be freely adjusted between 30-150r / min. The monitoring accuracy of the pressure monitoring device reaches ±0.01MPa. In addition, the top of the reactor is equipped with a raw material feed port and a gas discharge port, and a sight glass is installed on the side to facilitate observation of the reaction status. The bottom is equipped with a discharge port connecting the pipeline to achieve orderly transportation of materials.

[0025] The pretreated solid chloroacetic acid was crushed to a particle size of <1 mm and added to the recovered mother liquor in an optimized ratio to the primary reactor. The stirring device was turned on and stirred at a speed of 120 r / min to ensure thorough mixing of the materials. During the neutralization reaction stage, the temperature of the primary reactor was constantly controlled at 35°C. The pH of the reaction system was monitored in real time by an online pH detector. When the pH value was greater than 7, the neutralization reaction was determined to be complete. The materials then flowed into the subsequent reactors in sequence to enter the glycine production reaction stage. The reaction temperature was maintained stable at 50°C. The temperature control system was used to strictly control the insulation reaction temperature below 65°C. The entire reaction process lasted 3.5 hours. During this period, the pressure monitoring device monitored the system pressure in real time and maintained it at approximately 0.15 MPa. Simultaneously, a high-performance liquid chromatography online analyzer continuously monitored the concentration of the reaction liquid components. Based on the detection data, the central control system automatically fine-tuned the stirring speed, reaction temperature and other parameters to ensure efficient reaction.

[0026] The mixed liquid after the reaction is transported to a continuous crystallization kettle with a jacket through a pipeline. The jacket is connected to a low-temperature circulation device to provide a stable cooling medium. The agitator equipped with the crystallization kettle sets the stirring speed to 40r / min. In the absence of additional materials, the saturation characteristics of glycine and ammonium chloride in the mother liquor are utilized to slowly cool the temperature through the jacket to maintain it at 18°C. During this process, the two substances naturally precipitate to form an intermediate. The crystal growth morphology and particle size distribution are observed in real time with the help of a polarizing microscope to ensure the formation of an intermediate with a good crystal form and continuous crystallization. After the crystallization is completed, an automatic plate-pulling chamber filter press is used for solid-liquid separation. The separated mother liquor is collected through a pipeline to a mother liquor storage tank, waiting to be mixed with liquid chloroacetic acid and put into the reaction for recycling.

[0027] A WLS-450 horizontal spiral unloading sedimentation filter centrifuge was selected, and the drum speed was adjusted to 2500r / min. The ammonium chloride crystals and glycine mixture were transported to the centrifuge at a stable flow rate of 400L / h through a screw pump. During the centrifugal separation process, the washing system was simultaneously turned on, and methanol washing liquid with a temperature of 22°C was injected into the centrifuge at a mass ratio of 0.5:1 for washing. During the washing process, the flow rate and spraying angle of the washing water were adjusted to ensure that impurities on the crystal surface were fully cleaned. After centrifugation and washing, a granular product with a moisture content of about 6% and extremely low impurity content was obtained, laying a good foundation for the subsequent drying process.

[0028] The drying system utilizes a 500mm diameter and 10m long 316L stainless steel drying duct, equipped with a high-temperature nitrogen circulation system with intelligent temperature control. The high-temperature nitrogen temperature is set to 130°C and the flow rate is adjusted to 1800m³ / h. The granular product is evenly delivered into the drying duct via a screw conveyor. Under the strong purge of high-temperature nitrogen, the material is fully exposed to the hot air flow, achieving rapid drying. A pulse bag dust collector with a filtration accuracy of 0.1μm is installed at the outlet of the drying duct to effectively collect the dried glycine mixed crystal intermediates. The cooled nitrogen is sucked into the plate heat exchanger by a high-temperature resistant fan and heated to 130°C. It is then recirculated to the drying duct for drying, forming a closed-loop system. Testing has shown that the yield of this batch of glycine mixed crystal intermediates is as high as 99.95%, and the ammonium chloride exhibits a special crystal form, creating favorable conditions for subsequent product separation and purification. In addition, the energy consumption of the entire production process is significantly reduced, and the raw material utilization rate is greatly improved, meeting the requirements of green chemical production. Example

[0029] A 316L stainless steel continuous reactor is used, with a volume of 8m³ per reactor. The entire reactor is equipped with a DCS distributed control system to achieve precise automated control of the reaction process. The reactor temperature control system has an accuracy of ±0.3°C. The stirring device uses a variable frequency double-blade stirring device with an adjustable stirring speed between 30-150r / min. The pressure monitoring device has a real-time alarm function with a monitoring accuracy of ±0.005MPa.

[0030] After the solid chloroacetic acid is crushed to an average particle size of 0.8 mm, it is added to the primary reactor in sequence with the recovered mother liquor that has been deep filtered and formulated through the raw material metering feeding system. The stirring device is turned on and the stirring speed is adjusted to 130r / min to ensure that the raw materials are fully mixed. During the neutralization reaction stage, the temperature in the primary reactor is stably controlled at 42°C using a temperature control system. The pH value of the reaction system is monitored by an online pH detector. When the pH value is greater than 7, the neutralization reaction is determined to be complete. After the neutralization reaction is completed, the material automatically flows into the secondary reactor and enters the reaction stage of producing glycine. Figure 2 As shown, the reaction temperature is maintained at 48°C, and the insulation reaction temperature is strictly controlled not to exceed 65°C. The reaction time is set to 3.2 hours. During the entire reaction process, the pressure monitoring device monitors the pressure of the reaction system in real time to keep it stable at around 0.18 MPa. At the same time, the online infrared spectrometer continuously monitors the concentration changes of components such as glycine and ammonium chloride in the reaction solution. The central control system automatically adjusts parameters such as stirring speed and reaction temperature according to the monitoring data to ensure that the reaction is efficient and stable.

[0031] The mixed liquid after the reaction is transported via a pipeline to a continuous crystallization kettle equipped with an intelligent temperature control system. The jacket of the crystallization kettle uses a glycol-water mixed coolant with a temperature control accuracy of up to ±1°C. A low-speed stirring device is installed in the crystallization kettle with a stirring speed set to 35r / min. No additional materials are added to the crystallization kettle. The saturation characteristics of glycine and ammonium chloride in the mother liquor are utilized to slowly reduce the temperature in the crystallization kettle from 35°C to 22°C and maintain it through the intelligent temperature control system. The cooling rate is controlled at 0.5°C / min, prompting glycine and ammonium chloride to naturally precipitate to form intermediates. During the crystallization process, the growth and crystal structure of the crystals are observed under a microscope every 30 minutes to ensure the formation of uniform and stable crystals and continuous crystallization. A vacuum drum filter is used to separate the solid and liquid materials in the crystallization kettle. The separated mother liquor is collected in a special storage tank and waits to be mixed with liquid chloroacetic acid before being put into the reactor again for the next batch of production, thereby realizing the recycling of the mother liquor.

[0032] A horizontal spiral unloading sedimentation filter centrifuge model LW-520 was selected. The centrifuge was equipped with an automatic feed adjustment system and a washing liquid temperature control system. The centrifuge drum speed was adjusted to 2800r / min. The ammonium chloride crystals and glycine mixture were evenly transported to the centrifuge at a speed of 600L / h through the automatic feed adjustment system. During the centrifugal separation process, methanol washing liquid with a mass ratio of 1:1 to the mixed liquid was added to the centrifuge for washing. The washing liquid temperature was precisely controlled at 60°C by the temperature control system to improve the washing effect. During the washing process, the centrifuge automatically adjusted the drum speed and feed speed to ensure that the material was fully separated and washed in the centrifuge. After centrifugation and washing, a granular product with a moisture content of about 8% was obtained. The product particles were uniform and the impurity content was low.

[0033] A new energy-saving drying pipeline system is used. The pipeline body is made of 316L stainless steel, with an inner diameter of 600mm and a length of 12m. It is equipped with an efficient high-temperature nitrogen circulation heating device. The nitrogen temperature can be accurately adjusted between 90℃-160℃, and the flow range is 1200-2500m³ / h. A pneumatic conveying device is used to deliver the granular product after centrifugation and washing into the drying pipeline. The high-temperature nitrogen at a temperature of 140℃ and a flow rate of 2000m³ / h fully contacts the material to achieve rapid drying. A high-efficiency cyclone separator and pulse bag are set at the outlet of the drying pipeline. The combined collection device of the dust collector first separates most of the particles through a cyclone separator, and then uses a pulse bag dust collector for fine filtration with a filtration accuracy of 0.05μm, ensuring that the dried glycine mixed crystal intermediates are efficiently collected. The cooled nitrogen is pressurized by a fan and heated to 140°C by a heat exchanger, and then recirculated to the drying pipeline for drying. The entire drying process has high thermal efficiency and low energy consumption. After testing, the yield of this batch of glycine mixed crystal intermediates reached 99.96%. The product quality is excellent and the ammonium chloride crystal form is unique, providing high-quality raw materials for subsequent deep processing and product applications.

[0034] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for producing a glycine mixed crystal intermediate, characterized in that: The method comprises the following specific steps: Raw material mixing and temperature reaction: The pulverized solid or liquid chloroacetic acid is added to a continuous reactor together with the recovered mother liquor. In the continuous reactor, the reaction temperature of the neutralization reaction stage is controlled within the low-temperature reaction zone. After the neutralization reaction is completed, the reaction stage of producing glycine is entered. Through continuous reactions in multiple reactors, the mixed solution reaches the temperature conditions required for subsequent production. Crystallization intermediate precipitation: After the reaction in the continuous reactor is completed, the mixed liquid flows into the continuous crystallization reactor. In the crystallization reactor, the intermediate with a special crystal form is formed by the principle that glycine and ammonium chloride naturally precipitate after reaching a saturated state in the mother liquor. After the crystallization process is completed, the mother liquor separated in the crystallization reactor is recovered and mixed with new solid chloroacetic acid or liquid chloroacetic acid, and then put into the reactor to continue the reaction; Centrifugation and washing: The mixed solution of the crystallization intermediate and mother liquor flowing out of the crystallization kettle outlet enters the continuous centrifuge, where it is continuously centrifuged and washed to remove impurities in the mixed crystal intermediate and obtain a granular product with a certain humidity; Drying and collection: After continuous centrifugation and washing, the granular products are transported to the drying pipe. In the drying pipe, the particles are dried by the flow of high-temperature nitrogen. During the drying process, the dried particles are collected by the bag dust collector. The cooled nitrogen is reheated by the blower and heat exchange device, turning it into high-temperature nitrogen again and continuing to circulate in the drying pipe.

2. The method for producing a glycine mixed crystal intermediate according to claim 1, wherein In the raw material mixing and temperature-raising reaction step, the crushed solid chloroacetic acid or liquid chloroacetic acid and the recovered mother liquor are added to a continuous reactor, the stirring device is turned on, and the stirring speed is adjusted to 30-150 r / min to fully mix the raw materials. In the neutralization reaction stage, the temperature in the reactor is controlled at 20° C. to 50° C. using a temperature control system, and the pH value of the reaction system is detected to determine whether the neutralization reaction is complete by checking whether it is greater than 7.

3. The method for producing a glycine mixed crystal intermediate according to claim 1, wherein In the raw material mixing and temperature-raising reaction step, after the neutralization reaction is completed, the reaction stage of generating glycine is entered, the reaction temperature is maintained at 30° C.-50° C., the insulation reaction temperature does not exceed 65° C., and the reaction time is controlled within 4 hours.

4. The method for producing a glycine mixed crystal intermediate according to claim 1, wherein In the crystallization intermediate step, the mixed solution after the reaction in the continuous reactor is introduced into a continuous crystallization reactor, the temperature is controlled at 30°C-50°C, no other materials are added to the crystallization reactor, and the glycine mixed solution and ammonium chloride are naturally precipitated to form an intermediate after reaching saturation in the mother liquor. The temperature in the crystallization reactor is controlled to be maintained at 15°C-30°C for continuous crystallization.

5. The method for producing a glycine mixed crystal intermediate according to claim 1, wherein In the centrifugation and washing steps, the crystalline intermediate and the mother liquor mixture are transported to a continuous centrifuge through a pipeline, the centrifuge is turned on, the drum speed is adjusted to 900-4000 r / min, and solid-liquid separation is achieved under the action of centrifugal force. During the centrifugation process, methanol washing liquid is added to the centrifuge, and the mass ratio of the washing liquid to the crystalline intermediate is 0.1-1:1 for washing. The mother liquor and the washing liquid are collected and disposed of separately.

6. The method for producing a glycine mixed crystal intermediate according to claim 1, wherein In the centrifugation and washing steps, the temperature of the washing liquid is controlled at 20° C.-70° C., and after the centrifugation and washing are completed, a granular product with a moisture content of 2%-10% is obtained.

7. The method for producing a glycine mixed crystal intermediate according to claim 1, wherein: In the drying and collection steps, a conveying device is used to deliver the granular product after continuous centrifugation and washing into a drying pipe. High-temperature nitrogen is delivered to the drying pipe through a pipe, fully contacts the granular product, and the particles are dried by the heat of the high-temperature nitrogen. At the outlet of the drying pipe, a bag dust collector with a filtration accuracy of 0.1 μm is set to collect the dried particles. The cooled nitrogen flows out from the other end of the drying pipe and enters the blower and heat exchange device. Under the action of the blower, the nitrogen is compressed and reheated through the heat exchange device, and circulates into the drying pipe to participate in the subsequent drying process. The moisture content of the particles after drying is detected and controlled to be below 1%.

8. The method for producing a glycine mixed crystal intermediate according to claim 1, wherein In the drying and collecting steps, the temperature of the high-temperature nitrogen is 100°C-150°C, and the flow rate is controlled at 1000-200000 m³ / h.

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