A method for extracting glutamic acid directly from a glutamic acid fermentation broth by cation displacement dialysis

Abstract

The present application relates to the technical field of glutamic acid production, and particularly relates to a method for directly extracting glutamic acid from glutamic acid fermentation liquor by cation replacement dialysis, comprising the following steps: (1) cation replacement dialysis: glutamic acid fermentation liquor is introduced into a cation replacement dialysis device and an acid solution to perform cation replacement dialysis treatment, so as to obtain glutamic acid acid conversion liquor and ammonium salt, wherein the main component of the glutamic acid fermentation liquor is ammonium glutamate; (2) glutamic acid crystallization: the glutamic acid acid conversion liquor obtained in step (1) is crystallized to separate glutamic acid crystals, so as to obtain glutamic acid crystals and salt-free liquor. The present application can realize efficient conversion from ammonium glutamate to glutamic acid, and the method can improve the recovery rate of glutamic acid and simultaneously obtain high-purity ammonium salt.

Description

Technical Field

[0001] This invention relates to the field of glutamic acid production technology, specifically to a method for directly extracting glutamic acid from glutamic acid fermentation broth using cation exchange dialysis. Background Technology

[0002] Glutamic acid is an important amino acid widely used in the food and pharmaceutical industries. In recent years, biodegradable polymers (polyglutamic acid) synthesized from glutamic acid have received widespread attention and research. my country is a major producer of glutamic acid, with an annual output of 2.56 million tons (equivalent to 2.95 million tons of monosodium glutamate), accounting for 80% of global production, and annual exports exceeding 300,000 tons.

[0003] The industrial production of glutamic acid mainly relies on fermentation. In my country, the fermentation extraction process for glutamic acid has evolved from isoelectric exchange to concentrated isoelectric methods. The traditional isoelectric exchange process first uses low-temperature isoelectric crystallization to separate most of the glutamic acid, achieving a recovery rate of approximately 77% (the glutamic acid concentration entering the isoelectric fermentation broth is approximately 105 g / L). Then, cation exchange resin is used to further extract the remaining glutamic acid from the isoelectric mother liquor, achieving a final glutamic acid extraction yield of 96%. However, this process generates large amounts of wastewater with high concentrations of COD, ammonium sulfate, and low pH, and has since been phased out. Since 2010, the industrialized glutamic acid extraction process has primarily used continuous concentrated isoelectric methods. The continuous concentration isoelectric process concentrates the glutamic acid fermentation broth and then continuously crystallizes it at the isoelectric point. Compared with the isoelectric ionization process, it has advantages such as lower acid and alkali consumption and lower wastewater discharge. However, the glutamic acid recovery rate decreases, generally to 88-90% (the glutamic acid concentration in the concentrated glutamic acid fermentation broth entering the isoelectric point is approximately 320 g / L), which falls under the second level of clean production (according to the "Clean Production Standard for Monosodium Glutamate Industry" (HJ444-2008)). Simultaneously, the isoelectric mother liquor obtained from the glutamic acid crystallization contains a large amount of ammonium sulfate and other impurities. The production company evaporates and concentrates this mother liquor before spray granulation to prepare compound fertilizer. Although this method achieves resource recovery, the spray granulation process generates a large amount of organic waste gas, and the resulting compound fertilizer has low application value.

[0004] Patent application CN102086159A discloses a method for extracting glutamic acid, comprising the following steps: a) adjusting the pH of the fermentation broth to 2.9-3.2 at a temperature of 5-50℃, causing glutamic acid crystals to precipitate, separating the crystallized liquid to obtain crude glutamic acid and an isoelectric mother liquor; b) washing the crude glutamic acid from step a to obtain the finished glutamic acid and a washing mother liquor; sterilizing the isoelectric mother liquor from step a to obtain a clear mother liquor and bacterial cells; c) evaporating and concentrating the clear mother liquor from step b, cooling the resulting concentrate to 10-40℃, crystallizing, separating, and obtaining glutamic acid crystals and a crystallization mother liquor; d) mixing the glutamic acid crystals from step c and the washing mother liquor from step b, acidifying to less than 2.0 until the glutamic acid crystals dissolve to obtain an acidified solution; in step a, when adjusting the pH of the fermentation broth, the acidifying agent includes the acidified solution from step d. The above-mentioned glutamic acid extraction method has high yield and high purity, low material consumption, low energy consumption, low pollution discharge, and high resource utilization. However, this method still generates a large amount of waste liquid containing high concentrations of ammonium sulfate and other impurities, which poses difficulties for subsequent treatment. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to provide a method for directly extracting glutamic acid from glutamic acid fermentation broth (the main component of which is ammonium glutamate) using cation exchange dialysis. This method enables efficient conversion from ammonium glutamate to glutamic acid, improves the glutamic acid recovery rate, and simultaneously yields high-purity ammonium salts.

[0006] To achieve this objective, the present invention provides a method for directly extracting glutamic acid from glutamic acid fermentation broth using cation exchange dialysis, comprising the following steps:

[0007] (1) Cation exchange dialysis: The glutamic acid fermentation broth is passed into a cation exchange dialysis device and subjected to cation exchange dialysis with an acid solution to obtain glutamic acid-to-acid feed solution and ammonium salt. The main component of the glutamic acid fermentation broth is ammonium glutamic acid.

[0008] (2) Glutamic acid crystallization: The glutamic acid-converting solution obtained in step (1) is crystallized to separate the glutamic acid crystals and obtain glutamic acid crystals and salt-free solution.

[0009] The cation exchange dialysis device in step (1) includes one or more cation exchange dialysis modules connected in series and / or in parallel, as well as associated pumps, pipes, and valves. The cation exchange dialysis module includes a cation exchange dialysis membrane and a salt chamber and an acid chamber separated by the cation exchange dialysis membrane, such as... Figure 1As shown. The glutamic acid fermentation broth is passed into the salt chamber, and an acid solution (preferably a strong acid, such as sulfuric acid, hydrochloric acid, or nitric acid) is passed into the acid chamber as a replacement medium. Ammonium ions in the glutamic acid fermentation broth passing into the salt chamber and hydrogen ions in the acid solution passing into the acid chamber undergo ion exchange through a cation exchange dialysis membrane. That is, ammonium ions migrate across the cation exchange dialysis membrane into the acid chamber, and hydrogen ions migrate across the cation exchange dialysis membrane into the salt chamber. Thus, a glutamic acid-to-acid feed solution is obtained in the salt chamber, and an ammonium salt (such as ammonium sulfate, ammonium chloride, or ammonium nitrate) corresponding to the acid solution is obtained in the acid chamber. The glutamic acid-to-acid feed solution obtained in the salt chamber of the cation exchange dialysis device in step (1) is crystallized to separate the glutamic acid crystals, resulting in glutamic acid crystals and a salt-free feed solution. This salt-free feed solution is called the salt-free glutamic acid isoelectric mother liquor, hereinafter referred to as "salt-free mother liquor".

[0010] The cation exchange dialysis module can be a plate-and-frame cation exchange dialysis membrane stack, a tubular cation exchange dialysis membrane module, or a spiral wound cation exchange dialysis membrane module. The plate-and-frame cation exchange dialysis membrane stack includes multiple flat-plate cation exchange dialysis membranes and separators, as well as salt and acid chambers alternately separated by these multiple flat-plate cation exchange dialysis membranes, such as... Figure 2 As shown. The tubular cation exchange dialysis membrane module includes multiple tubular cation exchange dialysis membranes and salt chambers (outside the membrane tubes, shell side) and acid chambers (inside the membrane tubes, tube side) separated by the tubular cation exchange dialysis membranes, as shown. Figure 4 As shown. The spiral-wound cation exchange dialysis membrane assembly includes one or more flat cation exchange dialysis membranes rolled into a membrane roll and a separator, as well as salt and acid compartments separated by the cation exchange dialysis membrane, such as... Figure 5 As shown.

[0011] Preferably, in step (1), the number of multiple cation exchange dialysis components connected in series and / or in parallel is two, three, four, five, or six.

[0012] In this invention, the thickness of the partition plates in the plate-and-frame cation exchange dialysis membrane stack is 0.7-2 mm, for example, 0.7 mm, 1 mm, 1.3 mm, 1.6 mm, or 2 mm. The outer diameter of the tubular membrane in the tubular cation exchange dialysis membrane module is 1-10 mm, for example, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm, and the membrane tube wall thickness is 0.2-0.8 mm, for example, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, or 0.8 mm. The thickness of the mesh in the spiral-wound cation exchange dialysis membrane module is 0.7-2 mm, for example, 0.7 mm, 1 mm, 1.3 mm, 1.6 mm, or 2 mm.

[0013] The planar cation exchange membrane can be any cation exchange membrane well-known to those skilled in the art, readily available on the market, such as conventional electrodialysis cation exchange membranes, monovalent selective cation exchange membranes (i.e., ion exchange membranes that allow monovalent cations to pass through preferentially while blocking divalent and higher valence ions), or diffusion dialysis cation exchange membranes commonly used in conventional diffusion dialysis processes, or obtained through modification of ion exchange membranes (doping modification and surface modification). The tubular cation exchange membrane can be any tubular cation exchange membrane known to those skilled in the art, or the tubular cation exchange membrane described in patent CN202110726115.9 or the hollow fiber diffusion dialysis membrane described in CN201910201309.X.

[0014] In this invention, the linear velocity of the feed solution in the cation exchange dialysis treatment within the plate-and-frame cation exchange dialysis membrane stack, the tubular cation exchange dialysis membrane module, and the spiral wound cation exchange dialysis membrane module is 0.5-7 cm / s, for example, it can be 0.5 cm / s, 1 cm / s, 1.5 cm / s, 2 cm / s, 3 cm / s, 4 cm / s, 5 cm / s, 6 cm / s, or 7 cm / s, etc.

[0015] In step (1) of the present invention, the cation exchange dialysis treatment is carried out at a temperature of 20-60℃.

[0016] In step (1) of the present invention, the pH of the glutamic acid-to-acid feed solution obtained from the salt chamber of the cation exchange dialysis device is reduced to 3.0-3.3 before proceeding to step (2).

[0017] Preferably, when the supersolubility of glutamic acid (total dissolved glutamic acid concentration / glutamic acid solubility) in the glutamic acid-to-acid feed solution in the salt chamber of the cation exchange dialysis device in step (1) reaches 1.4-2, the glutamic acid-to-acid feed solution is transferred to a storage tank and seed crystals are added. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid feed solution containing glutamic acid crystals is returned to the salt chamber of the cation exchange dialysis device to continue the cation exchange dialysis in step (1) until the pH of the glutamic acid-to-acid feed solution obtained in the salt chamber of the cation exchange dialysis device decreases to 3.0-3.3. This can improve the glutamic acid recovery rate in the subsequent step (2) and obtain easily separable α-glutamic acid crystals.

[0018] The crystallization in step (2) adopts conventional cooling crystallization, for example, the crystallization temperature is 5-20℃, or the existing gradual cooling crystallization can be used. The equipment used for cooling crystallization or gradual cooling crystallization is a heat exchange crystallizer.

[0019] The separation in step (2) is performed by centrifugation or filtration by a vacuum belt filter.

[0020] The method provided by this invention employs a cation exchange dialysis membrane as the medium for ion exchange between two materials. It involves cation exchange dialysis of sterile or non-sterilized glutamic acid fermentation broth with an acid (preferably a strong acid, such as sulfuric acid, hydrochloric acid, or nitric acid). Glutamic acid is directly obtained in the salt chamber, and high-purity ammonium salts (e.g., ammonium sulfate, ammonium chloride, or ammonium nitrate) are obtained in the acid chamber. After crystallization of the glutamic acid in the salt chamber, glutamic acid crystals and a easily processed, salt-free glutamic acid isoelectric mother liquor are obtained. This invention avoids the problem of difficult separation of ammonium sulfate in the high-ammonium sulfate concentration isoelectric mother liquor produced in existing continuous concentration isoelectric processes, which necessitates concentration to obtain low-value byproducts. Furthermore, the glutamic acid recovery rate can reach over 92%, which is higher than that of existing continuous concentration isoelectric processes.

[0021] Preferably, the acid solution in step (1) includes any one or a combination of at least two of hydrochloric acid, nitric acid and sulfuric acid.

[0022] Preferably, the initial molar concentration (in terms of hydrogen ions) of the acid solution in step (1) is 0.4-2.0 mol / L, for example, it can be 0.4 mol / L, 0.8 mol / L, 1.5 mol / L, 1.8 mol / L or 2.0 mol / L, etc.

[0023] Preferably, the concentration of the initial glutamic acid fermentation broth (calculated as glutamic acid) in step (1) is 60-100 g / L.

[0024] In this invention, the aforementioned method for directly extracting glutamic acid from glutamic acid fermentation broth using cation exchange dialysis can be referred to as a single-stage processing method, the process of which is as follows: Figure 3 As shown. During step (1), glutamic acid crystals may adhere to the membrane surface of the cation exchange dialysis device membrane or accumulate inside the plate-and-frame cation exchange dialysis membrane stack, tubular cation exchange dialysis membrane assembly, or spiral wound cation exchange dialysis membrane assembly, leading to a decrease in hydrogen / ammonium ion migration flux, or even clogging of the flow channels of the plate-and-frame cation exchange dialysis membrane stack, tubular cation exchange dialysis membrane assembly, or spiral wound cation exchange dialysis membrane assembly. To solve the above technical problems, the present invention preferably increases the linear velocity of the feed solution in the salt chamber of the cation exchange dialysis device to more than 2 cm / s in the plate-and-frame cation exchange dialysis membrane stack, tubular cation exchange dialysis membrane assembly, and spiral wound cation exchange dialysis membrane assembly, or / and simultaneously blows air onto the membrane surface on the salt chamber side to eliminate membrane surface crystal adhesion, such as... Figure 4 As shown.

[0025] To further improve this problem, the method for directly extracting glutamic acid from glutamic acid fermentation broth using cation exchange dialysis described in this invention also includes a multi-stage processing method.

[0026] The multi-stage processing method involves repeating steps (1) and (2) multiple times. Each completion of step (1) and (2) is called a stage. The end of step (1) of each stage is determined by the concentration of glutamic acid crystals in the glutamic acid-to-acid feed solution in the salt chamber of the cation exchange dialysis device not exceeding 70 g / L. The glutamic acid-to-acid feed solution obtained from the salt chamber of the cation exchange dialysis device in step (1) is passed into the heat exchange crystallization tank in step (2) for cooling and crystallization. After separating the glutamic acid crystals, a desalted feed solution is obtained, ending the first stage. The desalted feed solution obtained from the first stage is then used as the feed solution for the salt chamber of the cation exchange dialysis device in step (1) to start the next stage of cation exchange dialysis treatment. The above process is repeated until the pH of the feed solution (glutamic acid-to-acid feed solution) in the salt chamber of the cation exchange dialysis device drops to 3.0-3.3.

[0027] Taking the two-segment operation method in multi-segment processing as an example (e.g.) Figure 6 As shown), the initial glutamic acid fermentation broth is fed into the salt chamber of the cation exchange dialysis device in step (1), and the initial acid solution is fed into the acid chamber of the cation exchange dialysis device in step (1) for cation exchange dialysis. The glutamic acid-converted feed solution obtained from the salt chamber of the cation exchange dialysis device is fed into the heat exchange crystallizer in step (2) for cooling and crystallization. After separating the glutamic acid crystals, a desalted feed solution is obtained, and the first stage ends. The desalted feed solution obtained in the first stage is fed back into the salt chamber of the cation exchange dialysis device in step (1) to start the second stage of cation exchange dialysis treatment. Ammonium salt is obtained in the acid chamber of the cation exchange dialysis device. The second stage of the acid-converted feed solution obtained from the salt chamber of the cation exchange dialysis device is fed into the heat exchange crystallizer for cooling and crystallization. After separating the glutamic acid crystals, a salt-free mother liquor is obtained, and the second stage ends.

[0028] Preferably, the operating temperature of the cation exchange dialysis treatment in step (1) of each segment of the multi-segment treatment method is 20-60℃, for example, it can be 20℃, 30℃, 40℃, 50℃ or 60℃, etc.

[0029] Preferably, in the multi-stage treatment method, the operating temperature of the cation exchange dialysis treatment in step (1) of each stage decreases progressively with the increase of the number of treatment stages. This is because the present invention has found that when the feed solution in the salt chamber of the cation exchange dialysis device is at a low pH, i.e., when the content of molecular glutamic acid is high, reducing the operating temperature of the cation exchange dialysis treatment in step (1) can significantly reduce the rate at which molecular glutamic acid leaks through the cation exchange dialysis membrane into the acid chamber, while having little effect on the rate at which hydrogen ions / ammonium ions cross the cation exchange membrane, thereby reducing the amount of glutamic acid leakage (loss) in the feed solution of the salt chamber of the cation exchange dialysis device.

[0030] For example, in the first stage of the multi-stage treatment method, that is, in the cation exchange dialysis process where the ammonium ion concentration in the salt chamber feed solution of the cation exchange dialysis device is high, a higher operating temperature is used, such as 45°C to 60°C; in the second stage of the multi-stage treatment method, that is, in the cation exchange dialysis process where the ammonium ion concentration in the salt chamber feed solution of the cation exchange dialysis device is at an intermediate level, an intermediate operating temperature is used, such as 30°C to 45°C; and in the third stage of the multi-stage treatment method, that is, in the cation exchange dialysis process where the ammonium ion concentration in the salt chamber feed solution of the cation exchange dialysis device is low, a lower operating temperature is used, such as 20°C to 30°C.

[0031] Preferably, the initial concentration of the glutamic acid fermentation broth (calculated as glutamic acid) in the multi-stage treatment method is 100-250 g / L.

[0032] The process employs a multi-stage treatment method. The first stage can recover 30%-85% of glutamic acid, and the ammonium ion removal rate in the first stage can reach 32%-90%.

[0033] The cation exchange dialysis in step (1) of the aforementioned method for directly extracting glutamic acid from glutamic acid fermentation broth using cation exchange dialysis can be referred to as a single-stage treatment method.

[0034] Preferably, step (1) of the method for directly extracting glutamic acid from glutamic acid fermentation broth using cation exchange dialysis according to the present invention further includes a multi-stage countercurrent treatment. The idea is to increase the concentration difference of inorganic cations across the cation exchange dialysis membrane, thereby increasing the migration flux of hydrogen and ammonium ions and reducing glutamic acid leakage.

[0035] The multi-stage countercurrent treatment method of cation exchange dialysis in step (1) involves setting up the cation exchange dialysis device into multiple cation exchange dialysis modules. Each cation exchange dialysis module is a stage, including a cation exchange dialysis membrane and salt and acid chambers separated by the cation exchange dialysis membrane. The salt chambers of multiple stages of cation exchange dialysis modules are connected in series, and the acid chambers of multiple stages of cation exchange dialysis modules are connected in series. The initial glutamic acid fermentation broth is passed into the salt chamber of the first-stage cation exchange dialysis module, and the initial acid solution is passed into the acid chamber of the last-stage cation exchange dialysis module. In the first stage, the initial glutamic acid fermentation broth (mainly composed of ammonium glutamate) undergoes cation exchange dialysis with the acid solution containing the lowest hydrogen ion concentration in the acid chamber of the cation exchange dialysis unit, which recovers ammonium salts. The resulting partially ammonium-free glutamic acid fermentation broth (ammonium glutamate solution) is then passed into the salt chamber of the next stage, where it undergoes cation exchange dialysis with the acid solution containing the intermediate hydrogen ion concentration in the acid chamber of the cation exchange dialysis unit. In the final stage, the initial acid solution undergoes cation exchange dialysis with the portion of the glutamic acid fermentation broth containing the lowest ammonium ion concentration in the salt chamber of the cation exchange dialysis unit, which recovers ammonium salts. The resulting partially ammonium-free acid solution is then passed into the acid chamber of the previous stage, where it undergoes cation exchange dialysis with the portion of the glutamic acid fermentation broth containing the intermediate ammonium ion concentration in the salt chamber of the cation exchange dialysis unit. This process continues in this manner. The final stage cation exchange dialysis unit yields a glutamic acid-to-acid feed solution in its salt chamber and an ammonium salt in its acid chamber.

[0036] Taking the three-stage reverse flow processing method in a multi-stage reverse flow processing approach as an example (e.g.) Figure 7 As shown, the initial glutamic acid fermentation broth is passed into the salt chamber 1 of the first-stage cation exchange dialysis unit, and the initial acid solution is passed into the acid chamber 3 of the third-stage cation exchange dialysis unit. The partially ammonium-depleted glutamic acid fermentation broth (glutamic acid ammonium solution) obtained from the salt chamber 1 is passed into the salt chamber 2 of the second-stage cation exchange dialysis unit, and the partially ammonium-recovered acid solution obtained from the acid chamber 3 is passed into the acid chamber 2 of the second-stage cation exchange dialysis unit. The partially ammonium-depleted glutamic acid fermentation broth (glutamic acid ammonium solution) obtained from the salt chamber 2 is passed into the third-stage salt chamber 3, and the partially ammonium-recovered acid solution obtained from the acid chamber 2 is passed into the first-stage acid chamber 1. The glutamic acid-to-acid feed solution is obtained in the salt chamber 3 of the third-stage cation exchange dialysis unit, and the ammonium salt is obtained in the acid chamber 1 of the first-stage cation exchange dialysis unit.

[0037] Preferably, in the multi-stage countercurrent treatment method of cation exchange dialysis in step (1), the initial concentration of glutamic acid fermentation broth (calculated as glutamic acid) is 60-100 g / L.

[0038] The method for directly extracting glutamic acid from glutamic acid fermentation broth using cation exchange dialysis according to the present invention also includes a multi-stage, multi-feature treatment method. The multi-stage, multi-feature treatment method employs the aforementioned multi-stage countercurrent treatment method in the cation exchange dialysis step (1) of each of the above-mentioned multi-stage treatment steps.

[0039] The multi-stage, multi-level treatment method involves repeating steps (1) and (2) multiple times. Each completion of steps (1) and (2) is called a stage. The end of step (1) of each stage is determined by the concentration of glutamic acid crystals in the glutamic acid-to-acid feed solution in the salt chamber of the cation exchange dialysis device not exceeding 70 g / L. The glutamic acid-to-acid feed solution obtained from the salt chamber of the cation exchange dialysis device in step (1) is then passed into the heat exchange crystallization tank in step (2) for cooling and crystallization. After separating the glutamic acid crystals, a desalted feed solution is obtained, thus ending the first stage. The desalted feed solution obtained from the first stage is then used as the feed solution for the salt chamber of the cation exchange dialysis device in step (1) to start the next stage of cation exchange dialysis treatment. The above process is repeated until the pH of the feed solution (glutamic acid-to-acid feed solution) in the salt chamber of the cation exchange dialysis device drops to 3.0-3.3.

[0040] In step (1), the cation exchange dialysis employs a multi-stage countercurrent treatment method. Specifically, the cation exchange dialysis device is configured as multiple cation exchange dialysis modules, each module being a stage, including a cation exchange dialysis membrane and salt and acid chambers separated by the membrane. The salt chambers of multiple stages of the cation exchange dialysis modules are connected in series, as are the acid chambers. At the beginning of step (1) in the first stage, the initial glutamic acid fermentation broth is introduced into the salt chamber of the first-stage cation exchange dialysis module, and the initial acid solution is introduced into the acid chamber of the last-stage cation exchange dialysis module. In the first stage, the initial glutamic acid fermentation broth (mainly composed of ammonium glutamate) undergoes cation exchange dialysis with the acid solution containing the lowest hydrogen ion concentration in the acid chamber of the cation exchange dialysis unit, which recovers ammonium salts. The resulting partially ammonium-free glutamic acid fermentation broth (ammonium glutamate solution) is then passed into the salt chamber of the next stage, where it undergoes cation exchange dialysis with the acid solution containing the intermediate hydrogen ion concentration in the acid chamber of the cation exchange dialysis unit. In the final stage, the initial acid solution undergoes cation exchange dialysis with the portion of the glutamic acid fermentation broth containing the lowest ammonium ion concentration in the salt chamber of the cation exchange dialysis unit, which recovers ammonium salts. The resulting partially ammonium-free acid solution is then passed into the acid chamber of the previous stage, where it undergoes cation exchange dialysis with the portion of the glutamic acid fermentation broth containing the intermediate ammonium ion concentration in the salt chamber of the cation exchange dialysis unit. This process continues in this manner. The final stage cation exchange dialysis unit yields a glutamic acid-to-acid feed solution in its salt chamber and an ammonium salt in its acid chamber. At the beginning of step (1) in the subsequent section, the desalted liquid obtained after separating glutamic acid crystals in step (2) of the previous section (replacing the initial glutamic acid fermentation liquid in step (1) of the first section) is introduced into the salt chamber of the first-stage cation exchange dialysis unit, and the initial acid solution is introduced into the acid chamber of the last-stage cation exchange dialysis unit, repeating the processing procedure of step (1) of the first section.

[0041] Taking the two-segment, three-level operation method in a multi-segment, multi-level processing approach as an example (e.g.) Figure 8(As shown). At the beginning of step (1) of the first stage, the initial glutamic acid fermentation broth is introduced into the salt chamber 1 of the first-stage cation exchange dialysis component, and the initial acid solution is introduced into the acid chamber 3 of the third-stage cation exchange dialysis component; the partially ammonium-depleted glutamic acid fermentation broth (glutamic acid ammonium solution) obtained from the salt chamber 1 is introduced into the salt chamber 2 of the second-stage cation exchange dialysis component, and the partially ammonium-recovered acid solution obtained from the acid chamber 3 is introduced into the acid chamber 2 of the second-stage cation exchange dialysis component; the partially ammonium-depleted glutamic acid fermentation broth (glutamic acid ammonium solution) obtained from the salt chamber 2 is introduced into the salt chamber 3 of the third-stage cation exchange dialysis component, and the partially ammonium-recovered acid solution obtained from the acid chamber 2 is introduced into the first-stage acid chamber 1; glutamic acid-to-acid feed solution is obtained in the salt chamber 3 of the third-stage cation exchange dialysis component, and ammonium salt is obtained in the acid chamber 1 of the first-stage cation exchange dialysis component. The glutamic acid-to-acid feed solution obtained in the salt chamber 3 of the third-stage cation exchange dialysis component is introduced into the heat exchange crystallizer in step (2) for cooling and crystallization. After separating the glutamic acid crystals, the desalted feed solution is obtained, and the first stage ends. At the beginning of step (1) of the second stage, the desalted feed solution obtained in the first stage is introduced into the salt chamber 1 of the first-stage cation exchange dialysis component in step (1), and the initial acid solution is introduced into the acid chamber 3 of the third-stage cation exchange dialysis component. The process of step (1) of the first stage is repeated. Glutamic acid-to-acid feed solution is obtained in the salt chamber 3 of the third-stage cation exchange dialysis component, and ammonium salt is obtained in the acid chamber 1 of the first-stage cation exchange dialysis component. The process of step (2) of the first stage is repeated. Glutamic acid crystals and desalted feed solution are obtained in the heat exchange crystallizer. After separating the glutamic acid crystals, a salt-free mother liquor is obtained, and the second stage ends.

[0042] Preferably, the operating temperature of the cation exchange dialysis treatment in step (1) of each segment in the multi-stage multi-processing method is 20-60℃, for example, it can be 20℃, 30℃, 40℃, 50℃ or 60℃.

[0043] Preferably, in the multi-stage multi-processing method, the operating temperature of the cation exchange dialysis treatment in step (1) of each stage decreases progressively with the increase of the number of treatment stages.

[0044] Preferably, the initial concentration of the glutamic acid fermentation broth (calculated as glutamic acid) in the multi-stage, multi-level treatment method is 100-250 g / L.

[0045] The method for directly extracting glutamic acid from glutamic acid fermentation broth using cation exchange dialysis as described in this invention also includes a mixed multi-stage, multi-processing method.

[0046] The multi-stage, multi-process hybrid method is as follows: the cation exchange dialysis device in step (1) is configured into multiple cation exchange dialysis modules, each of which is a stage, including a cation exchange dialysis membrane and salt and acid chambers separated by the cation exchange dialysis membrane. The salt chambers of each stage of the cation exchange dialysis module are connected to the heat exchange crystallizer in step (2), and the acid chambers of each stage of the cation exchange dialysis module are connected in series. The initial glutamic acid fermentation broth is fed into the salt chamber of the first-stage cation exchange dialysis module, and the initial acid solution is fed into the acid chamber of the last-stage cation exchange dialysis module. The acid solution obtained from the acid chamber of each stage, which recovers some ammonium salt, is fed into the acid chamber of the previous stage. The glutamic acid-to-acid feed solution obtained from the salt chamber of each stage of the cation exchange dialysis module in step (1) is fed into the heat exchange crystallizer in step (2) connected to it, completing one step (2), which is called a stage. The desalted feed solution obtained after separating glutamic acid crystals in the previous step (2) is passed into the salt chamber of the current cation exchange dialysis unit. The resulting glutamic acid-to-acid feed solution is then passed into the heat exchange crystallizer in step (2) of this section, completing one step (2) and ending this section. The segmentation is based on the fact that the concentration of glutamic acid crystals in the glutamic acid-to-acid feed solution in the salt chamber of each cation exchange dialysis unit does not exceed 70 g / L. This process continues until the pH of the feed solution (glutamic acid-to-acid feed solution) in the salt chamber of the cation exchange dialysis unit in step (1) of a certain stage drops to 3.0-3.3. Ammonium salt is obtained in the acid chamber of the first-stage cation exchange dialysis unit, and glutamic acid-to-acid feed solution is obtained in the salt chamber of the last-stage cation exchange dialysis unit. This feed solution is then passed into the heat exchange crystallizer of the last stage to obtain glutamic acid crystals and desalted feed solution. After separating the glutamic acid crystals, a salt-free mother liquor is obtained.

[0047] Taking the hybrid three-stage three-level countercurrent operation mode in the hybrid multi-stage multi-level processing method as an example (e.g.) Figure 9 (As shown). The initial glutamic acid fermentation broth is passed into the salt chamber 1 of the first-stage cation exchange dialysis unit, and the initial acid solution is passed into the acid chamber 3 of the third-stage cation exchange dialysis unit. The glutamic acid-to-acid feed solution obtained from the salt chamber 1 of the first-stage cation exchange dialysis unit is passed into the first-stage heat exchange crystallizer for cooling and crystallization. After separating the glutamic acid crystals, a desalted feed solution is obtained, ending the first stage. The desalted feed solution obtained from the first stage is passed into the salt chamber 2 of the second-stage cation exchange dialysis unit, and so on. Ammonium salt is obtained from the acid chamber 1 of the first-stage cation exchange dialysis unit, and the glutamic acid-to-acid feed solution is obtained from the salt chamber 3 of the third-stage cation exchange dialysis unit. This feed solution is passed into the third-stage heat exchange crystallizer to obtain glutamic acid crystals and a desalted feed solution. After separating the glutamic acid crystals, a salt-free mother liquor is obtained.

[0048] Preferably, the operating temperature of the cation exchange dialysis treatment in step (1) of each stage of the mixed multi-stage multi-level treatment method is 20-60℃, for example, it can be 20℃, 30℃, 40℃, 50℃ or 60℃.

[0049] Preferably, in the mixed multi-stage multi-processing method, the operating temperature of the cation exchange dialysis treatment in each stage (1) decreases step by step as the number of treatment stages increases.

[0050] Preferably, the initial concentration of glutamic acid fermentation broth (calculated as glutamic acid) in the mixed multi-stage multi-processing method is 100-250 g / L.

[0051] The technical solution of this invention employs multi-stage processing, multi-stage countercurrent processing, and a combination of both. Multi-stage processing can alleviate the problem of reduced ion migration flux caused by increased glutamate crystal concentration in the acid-to-salt solution of the cation exchange dialysis unit, and also reduce the phenomenon of glutamate crystals adhering to the membrane surface. Multi-stage countercurrent processing can increase the concentration difference between hydrogen and ammonium ions across the cation exchange dialysis membrane, thereby increasing their migration flux, while having a relatively small impact on the migration rate of glutamate. Therefore, this method can reduce glutamate leakage while increasing migration flux. The glutamate recovery rate of a single-stage, single-process method is 88%-93%, while multi-stage or multi-process methods can increase the glutamate recovery rate to 92%-94%. Multi-stage or mixed multi-stage processing methods achieve glutamate recovery rates higher than other methods, ranging from 93.3%-95.4%.

[0052] Compared with the prior art, the advantages of the present invention are:

[0053] (1) The method provided by this invention directly obtains glutamic acid and high-purity ammonium salt by desalting and converting to acid using a specific ion-exchange medium. The recovery rate of glutamic acid can reach over 92%, the removal rate of ammonium ions can reach over 96%, and the membrane flux is >2.8 mol / m³. 2 / h;

[0054] (2) Using the method provided by the present invention, the concentration of ammonium ions in the final salt-free mother liquor (salt-free glutamic acid isoelectric mother liquor) is <4g / L, and the concentration of acid radical ions leaked into the glutamic acid conversion solution is <5g / L. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of ion migration during the cation exchange dialysis process in the cation exchange dialysis device described in this invention;

[0056] Figure 2 This is the arrangement of the cation exchange dialysis membrane and the separator in the plate-and-frame cation exchange dialysis membrane stack described in this invention;

[0057] Figure 3 This is a process diagram of the method for directly extracting glutamic acid from glutamic acid fermentation broth using cation exchange dialysis as described in this invention (which can be called a single-stage processing method);

[0058] Figure 4 This is a schematic diagram of the internal structure of the tubular cation exchange dialysis membrane module described in this invention;

[0059] Figure 5 This is a schematic diagram of the internal structure of the spiral-wound cation exchange dialysis membrane module described in this invention;

[0060] Figure 6 This is a process diagram of the multi-segment processing method (taking two segments as an example) described in this invention;

[0061] Figure 7 This is a process diagram of the multi-stage countercurrent treatment method of cation exchange dialysis in step (1) of the present invention (taking the three-stage countercurrent treatment method as an example);

[0062] Figure 8 This is a process diagram of the multi-segment, multi-level processing method described in this invention (taking a two-segment, three-level processing method as an example);

[0063] Figure 9 This is a process diagram of the hybrid multi-segment multi-level processing method described in this invention (taking the hybrid three-segment three-level processing method as an example);

[0064] Figure 10 This is a process diagram of the three-stage processing method described in this invention;

[0065] Figure 11 This is a process diagram of the two-stage countercurrent processing method described in this invention;

[0066] Figure 12 This is a process diagram of the two-stage, two-level processing method described in this invention;

[0067] Figure 13 This is a process diagram of the three-stage, two-level processing method described in this invention;

[0068] Figure 14 This is a process diagram of the hybrid six-segment six-level processing method described in this invention;

[0069] Figure 15 This is a process diagram of the hybrid four-stage four-level processing method described in this invention;

[0070] In the diagram: Salt chamber 1 and acid chamber 1 represent the salt chamber and acid chamber of the first-stage cation exchange dialysis unit in the above treatment method, respectively; salt chamber 2 and acid chamber 2 represent the salt chamber and acid chamber of the second-stage cation exchange dialysis unit in the above treatment method, respectively; salt chamber 3 and acid chamber 3 represent the salt chamber and acid chamber of the third-stage cation exchange dialysis unit in the above treatment method, respectively; salt chamber 4 and acid chamber 4 represent the salt chamber and acid chamber of the fourth-stage cation exchange dialysis unit in the above treatment method, respectively; salt chamber 5 and acid chamber 5 represent the salt chamber and acid chamber of the fifth-stage cation exchange dialysis unit in the above treatment method, respectively; and salt chamber 6 and acid chamber 6 represent the salt chamber and acid chamber of the sixth-stage cation exchange dialysis unit in the above treatment method, respectively.

[0071] The dashed line indicates the material flow in the second segment, and the dotted line indicates the material flow in the third segment. Detailed Implementation

[0072] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0073] Example 1

[0074] The cation exchange dialysis unit uses a plate-and-frame cation exchange dialysis membrane stack, employing monovalent and divalent cation exchange membranes manufactured by Astom. The separator thickness is 0.7 mm. Nine cation exchange membranes with an effective area of ​​12.8 cm × 6.9 cm and ten separators of the same mesh size are alternately used to separate the salt and acid compartments. Figure 2 As shown. The heat exchange crystallizer uses a jacketed glass cup with an inner diameter of 75 mm and a height of 125 mm, with a working volume of 500 mL, and is stirred magnetically.

[0075] 300 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 90 g / L was passed into the salt chamber of a cation exchange dialysis apparatus, resulting in an ammonium ion concentration of 11.1 g / L. 300 mL of sulfuric acid (calculated as hydrogen ion) with a concentration of 0.8 mol / L was passed into the acid chamber of the same apparatus as the replacement medium for cation exchange dialysis. Figure 3 As shown. The linear velocity of the feed solution in each chamber within the membrane stack is 3 cm / s, and the temperature of the feed solution in each chamber is 50℃. Cation exchange dialysis is stopped when the pH of the glutamic acid-to-acid feed solution decreases to 3.3. The obtained glutamic acid-to-acid feed solution is then passed into a heat exchange crystallizer and cooled and crystallized at 5℃. The glutamic acid crystals are separated using a centrifuge to obtain glutamic acid crystals and an isoelectric mother liquor of unsalted glutamic acid.

[0076] The total recovery rate of glutamic acid was 88.6%, the ammonium ion removal rate was 90.2%, and the membrane flux was 2.8 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 1.3 g / L and a sulfate concentration of 4.5 g / L. The ammonium sulfate concentration obtained in the acid chamber of the cation exchange dialysis unit was 35.7 g / L.

[0077] Example 2

[0078] The cation exchange dialysis apparatus uses one plate-and-frame cation exchange dialysis membrane stack with a partition thickness of 2 mm and three cation exchange membranes, otherwise identical to Example 1. The heat exchange crystallization tank is the same as in Example 1. The storage tank for glutamic acid crystallization is a jacketed glass cup with an inner diameter of 75 mm and a height of 125 mm, with a working volume of 500 mL, and is magnetically stirred.

[0079] 300 mL of glutamic acid fermentation broth (100 g / L concentration, calculated as glutamic acid) was passed into the salt chamber of a cation exchange dialysis apparatus, resulting in an ammonium ion concentration of 12.2 g / L. 300 mL of hydrochloric acid (0.8 mol / L concentration, calculated as hydrogen ions) was then passed into the acid chamber of the same apparatus as the replacement medium for cation exchange dialysis. Figure 3 As shown. The linear velocity of the feed solution in each chamber within the membrane stack is 3 cm / s, and the temperature of the feed solution in each chamber is 60℃. When the supersolubility of glutamic acid in the glutamic acid-to-acid feed solution obtained from the salt chamber of the cation exchange dialysis device reaches 1.4 (at which point the pH is 4.1), the glutamic acid-to-acid feed solution is transferred to the storage tank and 8% seed crystals are added. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid feed solution containing glutamic acid crystals is returned to the salt chamber of the cation exchange dialysis device for continued cation exchange dialysis. Cation exchange dialysis is stopped when the pH of the glutamic acid-to-acid feed solution decreases to 3.0. The obtained glutamic acid-to-acid feed solution is then passed into a heat exchange crystallizer and cooled and crystallized at 5℃. The glutamic acid crystals are separated by centrifugation to obtain glutamic acid crystals and an isoelectric mother liquor of unsalted glutamic acid.

[0080] The total recovery rate of glutamic acid was 92.1%, the ammonium ion removal rate was 93.2%, and the membrane flux was 2.6 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 0.8 g / L and a chloride ion concentration of 3.5 g / L. The ammonium chloride concentration obtained in the acid chamber of the cation exchange dialysis unit was 33 g / L. The glutamic acid recovery rate was 3.5% higher than that under conditions without crystallization in the storage tank.

[0081] Example 3

[0082] The cation exchange dialysis device uses one plate-and-frame cation exchange dialysis membrane stack with a partition thickness of 0.9 mm and three cation exchange membranes; otherwise, it is the same as in Example 1. The heat exchange crystallizer is the same as in Example 1. The storage tank for glutamic acid crystallization is the same as in Example 2.

[0083] The salt chamber of the cation exchange dialysis apparatus is circulated with 300 mL of glutamic acid fermentation broth (calculated as glutamic acid) at a concentration of 60 g / L, while the acid chamber is circulated with 300 mL of nitric acid (calculated as hydrogen ions) at a concentration of 0.5 mol / L as the replacement medium. The linear velocity of the feed solution in each chamber within the membrane stack is 3 cm / s, and the temperature of the feed solution in each chamber is 20 °C. When the supersolubility of glutamic acid in the glutamic acid-to-acid feed solution obtained from the salt chamber of the cation exchange dialysis apparatus reaches 2.0 (pH 4.3), the glutamic acid-to-acid feed solution is transferred to a storage tank and 8% seed crystals are added. After crystallization in the storage tank for 30 min, the glutamic acid-to-acid feed solution containing glutamic acid crystals is returned to the salt chamber of the cation exchange dialysis apparatus for continued cation exchange dialysis. Cation exchange dialysis is stopped when the pH of the glutamic acid-to-acid feed solution decreases to 3.15. The obtained glutamic acid-converting solution was fed into a heat exchange crystallizer and cooled and crystallized at 5°C. The glutamic acid crystals were separated by a centrifuge to obtain glutamic acid crystals and an isoelectric mother liquor of salt-free glutamic acid.

[0084] The total recovery rate of glutamic acid was 92.9%, the ammonium ion removal rate was 94.0%, and the membrane flux was 1.4 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 0.6 g / L and a nitrate concentration of 2.5 g / L. The ammonium nitrate concentration obtained in the acid chamber of the cation exchange dialysis unit was 30 g / L.

[0085] Example 4

[0086] The cation exchange dialysis apparatus is the same as in Example 3. The heat exchange crystallizer is the same as in Example 1. The storage tank for glutamic acid crystal growth is the same as in Example 2.

[0087] The linear velocity of the feed solution in each chamber within the membrane stack is 7 cm / s, and the temperature of the feed solution in each chamber is 50℃. When the supersolubility of glutamic acid in the glutamic acid-to-acid feed solution obtained from the salt chamber of the cation exchange dialysis device reaches 1.8 (pH 4.3 at this point), the glutamic acid-to-acid feed solution is transferred to a storage tank and 8% seed crystals are added. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid feed solution containing glutamic acid crystals is returned to the salt chamber of the cation exchange dialysis device for continued cation exchange dialysis. Cation exchange dialysis is stopped when the pH of the glutamic acid-to-acid feed solution decreases to 3.2. The obtained glutamic acid-to-acid feed solution is then passed into a heat exchange crystallizer and cooled and crystallized at 10℃. The glutamic acid crystals are separated by centrifugation to obtain glutamic acid crystals and an isoelectric mother liquor of unsalted glutamic acid.

[0088] The total recovery rate of glutamic acid was 91.2%, the ammonium ion removal rate was 93.5%, and the membrane flux was 2.9 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 0.7 g / L and a sulfate concentration of 4.8 g / L. The ammonium sulfate concentration obtained in the acid chamber of the cation exchange dialysis unit was 37.2 g / L.

[0089] Example 5

[0090] The cation exchange dialysis device uses a tubular cation exchange dialysis membrane module. The preparation method of the tubular heterogeneous cation exchange membrane includes the following steps: (1) 250g of linear low-density polyethylene (Zhongyuan Petrochemical, 7050) is put into a 2L internal mixer (Guangdong Lina) and internally mixed at 120°C. After complete plasticization, 50g of polyisobutylene is added for mechanical grafting. After internal mixing for 20min, 25g of calcium stearate, 5g of antioxidant 1010 and 670g of [unclear text] are added. 001×7 type cation exchange resin powder was further intensively mixed for 20 minutes to obtain agglomerated ion exchange material; (2) The agglomerated ion exchange material obtained in step (1) was added to a single screw extruder (Nanjing JENTEK extruder SJ-30) and extruded at a temperature of 120℃ to 160℃ in each section of the barrel, a die head temperature of 120℃ and a screw speed of 15r / min to obtain a heterogeneous tubular cation exchange membrane with a wall thickness of 0.5mm, an outer diameter of 7mm and a length of 30cm. A tubular cation exchange dialysis membrane module is equipped with 8 of the above-mentioned tubular cation exchange membranes. The outside of the membrane tube is the salt chamber and the inside of the membrane tube is the acid chamber. The bottom of the membrane module is equipped with an air inlet to blow air onto the membrane surface on the salt chamber side. The air blowing rate is 1L / min. Figure 4 As shown. The heat exchange crystallization tank is the same as in Example 1.

[0091] The salt chamber of the cation exchange dialysis apparatus was purged with 300 mL of 60 g / L glutamic acid fermentation broth (calculated as glutamic acid), while the acid chamber was purged with 300 mL of 0.65 mol / L hydrochloric acid (calculated as hydrogen ions) as the replacement medium. The linear velocity of the feed solution in each chamber within the membrane module was 0.5 cm / s, and the temperature of the feed solution in each chamber was 50 °C. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid feed solution decreased to 3.2. The resulting glutamic acid-to-acid feed solution was then passed into a heat exchange crystallizer and cooled and crystallized at 5 °C. The glutamic acid crystals were separated by centrifugation to obtain glutamic acid crystals and an isoelectric mother liquor of unsalted glutamic acid.

[0092] The total recovery rate of glutamic acid was 86.8%, the ammonium ion removal rate was 88.5%, and the membrane flux was 1.9 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 0.8 g / L and a chloride ion concentration of 3.1 g / L. The ammonium chloride concentration obtained in the acid chamber of the cation exchange dialysis unit was 19.1 g / L.

[0093] Example 6

[0094] Glutamic acid is extracted using a two-stage processing method, such as... Figure 6As shown. The cation exchange dialysis apparatus is the same as in Example 2, except that it uses a conventional cation exchange membrane manufactured by Hangzhou Lanran Technology Co., Ltd. The heat exchange crystallization tank is the same as in Example 1. The storage tank for glutamic acid crystal growth is the same as in Example 2.

[0095] At the start of the first stage, 300 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 180 g / L, an ammonium ion concentration of 22 g / L, and a pH of 6.4 was introduced into the salt chamber of the cation exchange dialysis unit. 300 mL of sulfuric acid (calculated as hydrogen ion) with a concentration of 1.5 mol / L was introduced into the acid chamber as the replacement medium. The linear velocity of the feed solution in each chamber within the membrane stack was 3 cm / s, and the temperature of the feed solution in each chamber was 55-60℃. When the supersolubility of glutamic acid in the glutamic acid-to-acid feed solution obtained from the salt chamber of the cation exchange dialysis unit reaches 1.5 (pH 4.8 at this point), crystallization is initiated. The glutamic acid-to-acid feed solution is transferred to a storage tank with 8% seed crystals added. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid feed solution containing glutamic acid crystals is returned to the salt chamber of the cation exchange dialysis unit for continued cation exchange dialysis. Cation exchange dialysis is stopped when the pH of the glutamic acid-to-acid feed solution decreases to 4.7 (at this point, the concentration of glutamic acid crystals in the glutamic acid-to-acid feed solution is 70 g / L). The obtained glutamic acid-to-acid feed solution is then passed into a heat exchange crystallizer and cooled and crystallized at 5°C. The glutamic acid crystals are separated using a centrifuge, yielding glutamic acid crystals and 275 mL of desalted feed solution, thus ending the first stage. The glutamic acid recovery rate in the first stage is 49.4%, and the ammonium ion removal rate is 43.6%.

[0096] The desalting solution obtained from the first stage, with a pH of 5.2, a glutamic acid concentration of 97.1 g / L, and an ammonium ion concentration of 13.2 g / L, was fed into the salt chamber of the cation exchange dialysis unit. This, along with 300 mL of the recovered salt solution (0.99 mol / L hydrogen ion concentration and 9.3 g / L ammonium ion concentration) obtained from the acid chamber of the cation exchange dialysis unit, initiated the second stage of cation exchange dialysis. The temperature of the solutions in each chamber was maintained at 30-35℃. When the supersolubility of glutamic acid in the glutamic acid-to-acid solution obtained from the salt chamber of the cation exchange dialysis unit reached 1.5 (pH 4.8 at this point), crystallization was initiated. The glutamic acid-to-acid solution was transferred to a storage tank with 8% seed crystals added. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid solution containing glutamic acid crystals was returned to the salt chamber of the cation exchange dialysis unit for continued cation exchange dialysis. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid solution decreased to 3.3. The obtained glutamic acid-converting solution was fed into a heat exchange crystallizer and cooled and crystallized at 5°C. The glutamic acid crystals were separated by centrifugation, yielding glutamic acid crystals and 255 mL of unsalted glutamic acid isoelectric mother liquor, thus ending the second stage. The glutamic acid recovery rate in the second stage was 42.7%, and the ammonium ion removal rate was 43.6%.

[0097] The total recovery rate of glutamic acid was 92.1%, the ammonium ion removal rate was 87.2%, and the membrane flux was 1.4 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 3.3 g / L and a sulfate concentration of 4.9 g / L. The resulting ammonium sulfate concentration was 68.6 g / L. The glutamic acid recovery rate was 2.4% higher than that of the two-stage operation at 60℃.

[0098] Example 7

[0099] Glutamic acid is extracted using a three-stage processing method, such as... Figure 10 As shown. The thickness of the partition plate in the cation exchange dialysis device is 0.9 mm, and other aspects are the same as in Example 1. The heat exchange crystallizer is also the same as in Example 1.

[0100] At the start of the first stage, 300 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 250 g / L was introduced into the salt chamber of the cation exchange dialysis unit. The ammonium ion concentration was 30.6 g / L, and the pH was 6.3. 300 mL of nitric acid (calculated as hydrogen ions) with a concentration of 2.0 mol / L was introduced into the acid chamber as the replacement medium. The linear velocity of the feed solution in each chamber within the membrane stack was 7 cm / s, and the temperature of the feed solution in each chamber was 50-60℃. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid feed solution decreased to 4.55. The resulting glutamic acid-to-acid feed solution was then introduced into a heat exchange crystallizer and cooled and crystallized at 20℃. The glutamic acid crystals were separated by centrifugation, yielding glutamic acid crystals and 285 mL of desalted feed solution, thus ending the first stage. The glutamic acid recovery rate in the first stage was 28.4%, and the ammonium ion removal rate was 33.5%.

[0101] The desalting solution obtained from the first stage, with a pH of 5.28, a glutamic acid concentration of 193.5 g / L, and an ammonium ion concentration of 21.4 g / L, was fed into the salt chamber of a cation exchange dialysis unit. This, combined with 300 mL of partially recovered salt solution (1.4 mol / L hydrogen ion concentration and 10.3 g / L ammonium ion concentration) obtained from the acid chamber of the same unit, initiated the second stage of cation exchange dialysis. The linear velocity of the solution within the membrane stack in each chamber was 7 cm / s, and the temperature of the solution in each chamber was 35-40 °C. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid solution decreased to 4.14. The resulting glutamic acid-to-acid solution was then fed into a heat exchange crystallizer and cooled and crystallized at 10 °C. The glutamic acid crystals were separated using a centrifuge, yielding glutamic acid crystals and 275 mL of desalting solution, thus ending the second stage. The glutamic acid recovery rate in the second stage was 37.8%, and the ammonium ion removal rate was 35%.

[0102] The desalting solution obtained from the second stage, with a pH of 5.1, a glutamic acid concentration of 94.0 g / L, and an ammonium ion concentration of 10.5 g / L, was fed into the salt chamber of a cation exchange dialysis unit. This, combined with 305 mL of partially recovered salt solution (0.82 mol / L hydrogen ion concentration and 21.3 g / L ammonium ion concentration) obtained from the acid chamber of the same unit, initiated the third stage of cation exchange dialysis. The linear velocity of the solution within the membrane stack in each chamber was 7 cm / s, and the temperature of the solution in each chamber was 25-30 °C. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid solution decreased to 3.0. The resulting glutamic acid-to-acid solution was then fed into a heat exchange crystallizer and cooled and crystallized at 5 °C. The glutamic acid crystals were separated using a centrifuge, yielding glutamic acid crystals and 260 mL of unsalted glutamic acid isoelectric mother liquor, thus ending the third stage. The glutamic acid recovery rate in the third stage was 26.4%, and the ammonium ion removal rate was 24%.

[0103] The total recovery rate of glutamic acid was 92.6%, the ammonium ion removal rate was 92.5%, and the membrane flux was 2.7 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 2.6 g / L and a nitrate ion concentration of 3.2 g / L. The resulting ammonium nitrate concentration was 123.1 g / L.

[0104] Example 8

[0105] Glutamic acid is extracted using a two-stage processing method, such as... Figure 6 As shown. The cation exchange dialysis apparatus and heat exchange crystallizer are the same as in Example 3. The storage tank for glutamic acid crystal growth is the same as in Example 2.

[0106] At the start of the first stage, 300 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 100 g / L, an ammonium ion concentration of 12.8 g / L, and a pH of 6.6 is introduced into the salt chamber of the cation exchange dialysis unit. 300 mL of hydrochloric acid (calculated as hydrogen ions) with a concentration of 0.7 mol / L is introduced into the acid chamber as the replacement medium. The linear velocity of the feed solution in each chamber within the membrane stack is 3 cm / s, and the temperature of the feed solution in each chamber is 50 °C. When the supersolubility of glutamic acid in the glutamic acid-to-acid feed solution obtained from the salt chamber of the cation exchange dialysis unit reaches 2.0 (at which point the pH is 4.3), crystallization is initiated. The glutamic acid-to-acid feed solution is transferred to a storage tank with 8% seed crystals added. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid feed solution containing glutamic acid crystals is returned to the salt chamber of the cation exchange dialysis unit for continued cation exchange dialysis. When the pH of the glutamic acid conversion solution decreased to 4.78, cation exchange dialysis was stopped. The resulting glutamic acid conversion solution was then passed into a heat exchange crystallizer and cooled and crystallized at 20°C. The glutamic acid crystals were separated by centrifugation, yielding glutamic acid crystals and 280 mL of desalting solution, thus ending the first stage. The glutamic acid recovery rate in the first stage was 56.2%, and the ammonium ion removal rate was 64.2%.

[0107] The desalting solution obtained from the first stage, with a pH of 4.65, a glutamic acid concentration of 48.5 g / L, and an ammonium ion concentration of 4.9 g / L, was fed into the salt chamber of the cation exchange dialysis unit. This, along with 300 mL of partially recovered salt solution (0.5 mol / L hydrogen ion concentration and 7.9 g / L ammonium ion concentration) obtained from the acid chamber of the cation exchange dialysis unit, initiated the second stage of cation exchange dialysis. The linear velocity of the solution within the membrane stack in each chamber was 3 cm / s, and the temperature of the solution in each chamber was 30°C. When the supersolubility of glutamic acid in the glutamic acid-to-acid solution obtained from the salt chamber of the cation exchange dialysis unit reached 2.0 (at which point the pH was 3.9), crystallization was initiated. The glutamic acid-to-acid solution was transferred to a storage tank with 8% seed crystals added. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid solution containing glutamic acid crystals was returned to the salt chamber of the cation exchange dialysis unit to continue cation exchange dialysis. When the pH of the glutamic acid conversion solution decreased to 3.2, cation exchange dialysis was stopped, and the solution was passed into a heat exchange crystallizer for cooling and crystallization at 5°C. The glutamic acid crystals were separated by centrifugation, yielding glutamic acid crystals and 270 mL of unsalted glutamic acid isoelectric mother liquor, thus ending the second stage. The glutamic acid recovery rate in the second stage was 37.3%, and the ammonium ion removal rate was 29.6%.

[0108] The total recovery rate of glutamic acid was 93.5%, the ammonium ion removal rate was 93.8%, and the membrane flux was 2.2 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 0.88 g / L and a chloride ion concentration of 2.2 g / L. The resulting ammonium chloride concentration was 34.9 g / L.

[0109] Example 9

[0110] Glutamic acid is extracted using a two-stage countercurrent treatment method, such as... Figure 11 As shown. The cation exchange dialysis device is configured as two identical plate-and-frame cation exchange dialysis membrane stacks, each stack being a single stage, and each stack is the same as in Example 3. The salt chambers of the two stacks are connected in series, and the acid chambers of the two stacks are connected in series. The heat exchange crystallization tank is a jacketed glass cup with an inner diameter of 95 mm and a height of 140 mm, with a working volume of 1000 mL, and is magnetically stirred. The storage tank for glutamic acid crystallization is a jacketed glass cup with an inner diameter of 95 mm and a height of 140 mm, with a working volume of 1000 mL, and is magnetically stirred.

[0111] The first-stage cation exchange dialysis unit introduces 600 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 95 g / L, an ammonium ion concentration of 12.0 g / L, and a pH of 6.4 into the salt chamber. The second-stage cation exchange dialysis unit introduces 600 mL of sulfuric acid (calculated as hydrogen ion) with a concentration of 0.68 mol / L into the acid chamber as the replacement medium. The linear velocity of the feed solution in each chamber within the membrane stack is 7 cm / s, and the feed solution temperature in each chamber is 20-25℃. In the first stage, the initial glutamic acid fermentation broth and 600 mL of partially recovered ammonium salt acid solution (0.36 mol / L hydrogen ion concentration and 5.6 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit were subjected to first-stage cation exchange dialysis. When the glutamic acid supersolubility of the glutamic acid-to-acid feed solution obtained from the salt chamber of this stage cation exchange dialysis unit reached 1.5 (pH 4.83), crystallization was carried out. After crystallization in the storage tank for 30 min, the glutamic acid-to-acid feed solution containing glutamic acid crystals was then... The solution is returned to the salt chamber of the first-stage cation exchange dialysis unit for further cation exchange dialysis. The glutamic acid-to-acid solution obtained from the salt chamber of the first-stage cation exchange dialysis unit has a pH of 4.73 and an ammonium ion concentration of 6.4 g / L. It is then subjected to a second-stage cation exchange dialysis with the initial acid solution. When the pH of the glutamic acid-to-acid solution decreases to 3.16, the cation exchange dialysis is stopped, and the solution is then fed into a heat exchange crystallizer for cooling and crystallization at 5°C. The glutamic acid crystals are separated by centrifugation to obtain glutamic acid crystals and an isoelectric mother liquor of unsalted glutamic acid.

[0112] The total glutamic acid yield was 93.2%, the ammonium ion removal rate was 94.1%, and the membrane flux was 1.6 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 0.7 g / L and a sulfate concentration of 2.5 g / L. The ammonium sulfate concentration obtained in the acid chamber of the first-stage cation exchange dialysis unit was 40.7 g / L. The glutamic acid yield was 1.5% higher than that without fractionation, and the membrane flux was 16% higher.

[0113] Example 10

[0114] Glutamic acid is extracted using a three-stage countercurrent treatment process, such as... Figure 7 As shown. The cation exchange dialysis apparatus is configured with three identical tubular cation exchange dialysis membrane modules, each module being a single stage. Each membrane module is the same as in Example 5, with the salt chambers of the three membrane modules connected in series and the acid chambers of the three membrane modules connected in series. The heat exchange crystallizer is the same as in Example 9.

[0115] The first-stage cation exchange dialysis module introduces 900 mL of glutamic acid fermentation broth (calculated as glutamic acid) at a concentration of 100 g / L into the salt chamber, with an ammonium ion concentration of 14.7 g / L and a pH of 6.5. The third-stage cation exchange dialysis module introduces 900 mL of hydrochloric acid (calculated as hydrogen ions) at a concentration of 0.9 mol / L into the acid chamber as the replacement medium. The linear velocity of the feed solution within each chamber is 2 cm / s, and the feed solution temperature in each chamber is 30-35℃. In the first stage, the initial glutamic acid fermentation broth was subjected to first-stage cation exchange dialysis with 900 mL of partially recovered ammonium salt solution (0.35 mol / L hydrogen ion concentration and 9.4 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit. The glutamic acid-to-acid feed solution obtained from the salt chamber of the first-stage cation exchange dialysis unit had a pH of 4.71 and an ammonium ion concentration of 10.9 g / L. This solution was then subjected to first-stage cation exchange dialysis with 900 mL of partially recovered ammonium salt solution (0.65 mol / L hydrogen ion concentration and 9.4 g / L ammonium ion concentration) recovered from the acid chamber of the third-stage cation exchange dialysis unit. A partial acid solution of recovered ammonium salt with an ion concentration of 4.2 g / L was subjected to a second-stage cation exchange dialysis. The glutamic acid-to-acid feed solution obtained from the salt chamber of the second-stage cation exchange dialysis unit had a pH of 4.5 and an ammonium ion concentration of 5.5 g / L. This feed solution was then subjected to a third-stage cation exchange dialysis with the initial acid solution. When the pH of the glutamic acid-to-acid feed solution decreased to 3.3, the cation exchange dialysis was stopped, and the solution was then passed into a heat exchange crystallizer for cooling and crystallization at 5°C. The glutamic acid crystals were separated by centrifugation to obtain glutamic acid crystals and an isoelectric mother liquor of unsalted glutamic acid.

[0116] The total yield of glutamic acid was 90.6%, the ammonium ion removal rate was 91.3%, and the membrane flux was 2.6 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 1.4 g / L and a chloride ion concentration of 3.7 g / L. The ammonium chloride concentration obtained in the acid chamber of the first-stage cation exchange dialysis unit was 39.3 g / L.

[0117] Example 11

[0118] Glutamic acid is extracted using a two-stage countercurrent treatment method, such as... Figure 11 As shown, the cation exchange dialysis unit is configured with two identical spiral-wound cation exchange dialysis membrane modules, each module serving as a single stage. Each module uses a flat-sheet cation exchange membrane manufactured by Liaoning Yichen Membrane Technology Co., Ltd., with a spacer thickness of 0.9 mm and an effective membrane area of ​​0.5 m² / s. 2 The membrane has salt chambers and acid chambers on both sides, such as... Figure 5 As shown. The salt chambers of the two membrane modules are connected in series, and the acid chambers of the two membrane modules are connected in series. The heat exchange crystallizer is the same as in Example 9. The storage tank for glutamic acid crystallization is the same as in Example 9.

[0119] In the first-stage cation exchange dialysis module, 600 mL of glutamic acid fermentation broth (calculated as glutamic acid) with a concentration of 60 g / L was introduced into the salt chamber, with an ammonium ion concentration of 7.4 g / L and a pH of 6.4. In the second-stage cation exchange dialysis module, 600 mL of nitric acid (calculated as hydrogen ions) with a concentration of 0.5 mol / L was introduced into the acid chamber as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution in each chamber within the membrane module was 4 cm / s, and the feed solution temperature in each chamber was 50 °C.

[0120] In the first stage, the initial glutamic acid fermentation broth is subjected to first-stage cation exchange dialysis with 600 mL of partially recovered ammonium salt acid solution (0.31 mol / L hydrogen ion concentration and 3.4 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit. The glutamic acid-to-acid feed solution obtained from the salt chamber of the first-stage cation exchange dialysis unit has a pH of 4.37 and an ammonium ion concentration of 4 g / L. This solution is then subjected to second-stage cation exchange dialysis with the initial acid solution. When the glutamic acid in the glutamic acid-to-acid feed solution obtained from the salt chamber of this stage of cation exchange dialysis unit becomes supersoluble... When the solubility reaches 2.0 (pH 3.81 at this point), crystallization is carried out. The glutamic acid conversion solution is transferred to a storage tank and 8% seed crystals are added. After crystallization in the storage tank for 30 minutes, the glutamic acid conversion solution containing glutamic acid crystals is returned to the salt chamber of the second-stage cation exchange dialysis component to continue cation exchange dialysis. When the pH of the glutamic acid conversion solution drops to 3.0, cation exchange dialysis is stopped, and the solution is passed into a heat exchange crystallizer for cooling and crystallization at 5°C. The glutamic acid crystals are separated by centrifugation to obtain glutamic acid crystals and an isoelectric mother liquor of unsalted glutamic acid.

[0121] The total yield of glutamic acid was 91.5%, the ammonium ion removal rate was 92.8%, and the membrane flux was 2.8 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 0.5 g / L and a nitrate ion concentration of 1.8 g / L. The ammonium nitrate concentration obtained in the acid chamber of the first-stage cation exchange dialysis unit was 29.6 g / L.

[0122] Example 12

[0123] Glutamic acid is extracted using a two-stage, two-phase countercurrent treatment method, such as... Figure 12 As shown. The cation exchange dialysis apparatus is configured as two identical plate-and-frame cation exchange dialysis membrane stacks, each stack being a single stage, and each stack being the same as in Example 3. The salt chambers of the two stacks are connected in series, and the acid chambers of the two stacks are connected in series. The heat exchange crystallizer is the same as in Example 9. The storage tank for glutamic acid crystallization is the same as in Example 9.

[0124] At the start of the first stage, 600 mL of glutamic acid fermentation broth (calculated as glutamic acid) at a concentration of 100 g / L was introduced into the salt chamber of the first-stage cation exchange dialysis unit. The ammonium ion concentration was 12.2 g / L, and the pH was 6.6. 300 mL of hydrochloric acid (calculated as hydrogen ions) at a concentration of 1.0 mol / L was introduced into the acid chamber of the second-stage cation exchange dialysis unit as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution within the membrane stack in each chamber was 2 cm / s, and the feed solution temperature in each chamber was 40 °C. In the first stage, the initial glutamic acid fermentation broth is subjected to first-stage cation exchange dialysis with 300 mL of partially recovered ammonium salt acid solution (0.51 mol / L hydrogen ion concentration and 8.5 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit. The glutamic acid-to-acid feed solution obtained from the salt chamber of the first-stage cation exchange dialysis unit has a pH of 4.52 and an ammonium ion concentration of 7.9 g / L. This solution is then subjected to second-stage cation exchange dialysis with the initial acid solution. When the supersolubility of glutamic acid in the glutamic acid-to-acid feed solution obtained from the salt chamber of this stage of the cation exchange dialysis unit reaches... At pH 4.55 (1.55), crystallization was initiated. The glutamic acid-to-acid solution was transferred to a storage tank with 8% seed crystals added. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid solution containing glutamic acid crystals was returned to the salt chamber of the second-stage cation exchange dialysis unit for continued cation exchange dialysis. When the pH of the glutamic acid-to-acid solution decreased to 4.42, cation exchange dialysis was stopped, and the solution was passed into a heat exchange crystallizer for cooling and crystallization at 15°C. The glutamic acid crystals were separated by centrifugation, yielding glutamic acid crystals and 574 mL of desalted solution, thus ending the first stage. The glutamic acid recovery rate in the first stage was 61.2%, the ammonium ion removal rate was 70.5%, and 300 mL of ammonium chloride with a concentration of 50.3 g / L was recovered in the first stage.

[0125] At the start of the second stage, the desalting solution obtained from the first stage, with a pH of 4.71, a glutamic acid concentration of 41.5 g / L, and an ammonium ion concentration of 3.8 g / L, is introduced into the salt chamber of the first-stage cation exchange dialysis unit. 300 mL of 0.4 mol / L hydrochloric acid (calculated as hydrogen ions) is introduced into the acid chamber of the second-stage cation exchange dialysis unit as the replacement medium. The linear velocity of the solution within the membrane stack in each chamber is 2 cm / s, and the temperature of the solution in each chamber is 15 °C. In the first stage, the desalted feed solution is subjected to first-stage cation exchange dialysis with 300 mL of partially recovered ammonium salt acid solution (0.23 mol / L hydrogen ion concentration and 3.0 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit. The glutamic acid-to-acid feed solution obtained from the salt chamber of the first-stage cation exchange dialysis unit has a pH of 4.61 and an ammonium ion concentration of 2.3 g / L. This solution is then subjected to second-stage cation exchange dialysis with the initial acid solution. When the glutamic acid supersolubility in the glutamic acid-to-acid feed solution obtained from the salt chamber of this stage of the cation exchange dialysis unit reaches 1.5... Crystallization was carried out at pH 4.19. The glutamic acid-to-acid solution was transferred to a storage tank and 8% seed crystals were added. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid solution containing glutamic acid crystals was returned to the salt chamber of the second-stage cation exchange dialysis unit for continued cation exchange dialysis. When the pH of the glutamic acid-to-acid solution decreased to 3.2, cation exchange dialysis was stopped, and the solution was passed into a heat exchange crystallizer for cooling and crystallization at 5°C. The glutamic acid crystals were separated by centrifugation, yielding glutamic acid crystals and 560 mL of unsalted glutamic acid isoelectric mother liquor, thus ending the second stage. The glutamic acid recovery rate in the second stage was 33.7%, the ammonium ion removal rate was 24.8%, and 300 mL of ammonium chloride with a concentration of 17.7 g / L was recovered in the first stage.

[0126] The total yield of glutamic acid was 94.9%, the ammonium ion removal rate was 95.3%, and the membrane flux was 2.6 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 0.7 g / L and a chloride ion concentration of 3.2 g / L.

[0127] Example 13

[0128] Glutamic acid is extracted using a two-stage, three-level processing method, such as... Figure 8 As shown. The cation exchange dialysis device is configured as three identical plate-and-frame cation exchange dialysis membrane stacks, each stack being a single stage. Each stack uses a conventional cation exchange membrane manufactured by Liaoning Yichen Membrane Technology Co., Ltd., with a separator thickness of 1.0 mm. Other aspects are the same as in Example 3. The salt chambers of the three membrane stacks are connected in series, and the acid chambers of the three membrane stacks are connected in series. The heat exchange crystallization tank is the same as in Example 9. The storage tank for glutamic acid crystal growth is the same as in Example 9.

[0129] At the start of the first stage, 900 mL of glutamic acid fermentation broth (calculated as glutamic acid) at a concentration of 160 g / L was introduced into the salt chamber of the first-stage cation exchange dialysis unit. The ammonium ion concentration was 19.6 g / L, and the pH was 6.3. 450 mL of sulfuric acid (calculated as hydrogen ion) at a concentration of 1.1 mol / L was introduced into the acid chamber of the third-stage cation exchange dialysis unit as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution within the membrane stack in each chamber was 5 cm / s, and the feed solution temperature in each chamber was 30-35℃. In the first stage, the initial glutamic acid fermentation broth is subjected to first-stage cation exchange dialysis with 450 mL of partially recovered ammonium salt acid solution (0.6 mol / L hydrogen ion concentration and 9.2 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit. The glutamic acid-to-acid feed solution obtained from the salt chamber of the first-stage cation exchange dialysis unit has a pH of 5.0 and an ammonium ion concentration of 16.3 g / L. This is then subjected to second-stage cation exchange dialysis with 450 mL of partially recovered ammonium salt acid solution (0.9 mol / L hydrogen ion concentration and 4.2 g / L ammonium ion concentration) recovered from the acid chamber of the third-stage cation exchange dialysis unit. The process continues until the supersolubility of the glutamic acid-to-acid feed solution obtained from the salt chamber of this stage of cation exchange dialysis unit reaches 1.6. (At this point, the pH is 4.6) Crystallization was carried out by transferring the glutamic acid-to-acid solution to a storage tank and adding 8% seed crystals. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid solution containing glutamic acid crystals was returned to the salt chamber of the second-stage cation exchange dialysis unit for further cation exchange dialysis. The glutamic acid-to-acid solution obtained in the salt chamber of the second-stage cation exchange dialysis unit had a pH of 4.9 and an ammonium ion concentration of 13.8 g / L. This solution was then subjected to a third-stage cation exchange dialysis with the initial acid solution. When the pH of the glutamic acid-to-acid solution decreased to 4.7, the cation exchange dialysis was stopped, and the solution was passed into a heat exchange crystallizer for cooling and crystallization at 15°C. The glutamic acid crystals were separated by centrifugation, yielding glutamic acid crystals and 780 mL of desalted solution, thus ending the first stage. The glutamic acid recovery rate in the first stage was 44.7%, and the ammonium ion removal rate was 45.2%. 450 mL of ammonium sulfate with a concentration of 64.2 g / L was recovered in the first stage.

[0130] At the start of the second stage, the desalting solution obtained from the first stage, with a pH of 5.0, a glutamic acid concentration of 115.8 g / L, and an ammonium ion concentration of 12.4 g / L, is introduced into the salt chamber of the first-stage cation exchange dialysis unit. 450 mL of 1.1 mol / L sulfuric acid (calculated as hydrogen ions) is introduced into the acid chamber of the third-stage cation exchange dialysis unit as the replacement medium. Operating conditions are the same as in the first stage. In the first stage, the desalted feed solution and 450 mL of partially recovered ammonium salt acid solution (0.4 mol / L hydrogen ion concentration and 10.8 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit are subjected to first-stage cation exchange dialysis. When the supersolubility of the glutamic acid-to-acid feed solution obtained from the salt chamber of this stage cation exchange dialysis unit reaches 1.8 (pH 4.8), crystallization is performed. The glutamic acid-to-acid feed solution is transferred to a storage tank and 8% seed crystals are added. After crystallization in the storage tank for 30 min, the glutamic acid-to-acid feed solution containing glutamic acid crystals is returned to the salt chamber of the first-stage cation exchange dialysis unit for continued cation exchange dialysis. The pH of the glutamic acid-to-acid feed solution obtained from the salt chamber of the first-stage cation exchange dialysis unit is 4. 7. An ammonium ion concentration of 7.8 g / L was used in a second-stage cation exchange dialysis process with 450 mL of partially recovered ammonium salt solution (0.8 mol / L hydrogen ion concentration and 5.1 g / L ammonium ion concentration) recovered from the acid chamber of the third-stage cation exchange dialysis unit. The glutamic acid-to-acid feed solution obtained from the salt chamber of the second-stage cation exchange dialysis unit had a pH of 4.5 and an ammonium ion concentration of 4.5 g / L. This solution was then used in a third-stage cation exchange dialysis process with the initial acid solution. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid feed solution decreased to 3.3, and the solution was then passed into a heat exchange crystallizer and cooled and crystallized at 5°C. The glutamic acid crystals were separated by centrifugation, yielding glutamic acid crystals and 735 mL of unsalted glutamic acid isoelectric mother liquor, thus ending the second stage. The glutamic acid recovery rate in the second stage was 48.3%, and the ammonium ion removal rate was 50.2%. 450 mL of ammonium sulfate with a concentration of 69.0 g / L was recovered in the first stage.

[0131] The total glutamic acid yield was 93.8%, the ammonium ion removal rate was 94.2%, and the membrane flux was 1.9 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 1.5 g / L and a sulfate ion concentration of 3.3 g / L.

[0132] Example 14

[0133] Glutamic acid is extracted using a three-stage, two-stage countercurrent treatment method, such as... Figure 13 As shown. The cation exchange dialysis apparatus is configured as two identical plate-and-frame cation exchange dialysis membrane stacks, each stack being a single stage, and each stack being the same as in Example 3. The salt chambers of the two stacks are connected in series, and the acid chambers of the two stacks are connected in series. The heat exchange crystallizer is the same as in Example 9. The storage tank for glutamic acid crystallization is the same as in Example 9.

[0134] At the start of the first stage, 600 mL of glutamic acid fermentation broth (calculated as glutamic acid) at a concentration of 250 g / L was introduced into the salt chamber of the first-stage cation exchange dialysis unit. The ammonium ion concentration was 32.4 g / L, and the pH was 6.4. 300 mL of nitric acid (calculated as hydrogen ions) at a concentration of 1.33 mol / L was introduced into the acid chamber of the second-stage cation exchange dialysis unit as the replacement medium for cation exchange dialysis. The linear velocity of the feed solution within the membrane stack in each chamber was 3 cm / s, and the feed solution temperature in each chamber was 50 °C. In the first stage, the initial glutamic acid fermentation broth and 300 mL of partially recovered ammonium salt acid solution (0.70 mol / L hydrogen ion concentration and 11.0 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit were subjected to first-stage cation exchange dialysis. When the glutamic acid supersolubility of the glutamic acid-to-acid feed solution obtained from the salt chamber of this stage cation exchange dialysis unit reached 2.0 (pH 5.19), crystallization was carried out. The glutamic acid-to-acid feed solution was transferred to a storage tank and 8% seed crystals were added. After crystallization in the storage tank for 30 min, the glutamic acid crystals were collected. The glutamic acid-to-acid feed solution was returned to the salt chamber of the first-stage cation exchange dialysis unit for further cation exchange dialysis. The glutamic acid-to-acid feed solution obtained in the salt chamber of the first-stage cation exchange dialysis unit had a pH of 5.3 and an ammonium ion concentration of 21 g / L. This solution was then subjected to a second-stage cation exchange dialysis with the initial acid solution. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid feed solution decreased to 5.1, and the solution was then passed into a heat exchange crystallizer for cooling and crystallization at 15°C. The glutamic acid crystals were separated by centrifugation, yielding glutamic acid crystals and 580 mL of desalted feed solution, thus ending the first stage. The glutamic acid recovery rate in the first stage was 34.9%, the ammonium ion removal rate was 35%, and 300 mL of ammonium nitrate with a concentration of 97.9 g / L was recovered in the first stage.

[0135] At the start of the second stage, the desalting solution obtained from the first stage, with a pH of 5.5, a glutamic acid concentration of 172.6 g / L, and an ammonium ion concentration of 21.7 g / L, was introduced into the salt chamber of the first-stage cation exchange dialysis unit. 300 mL of 1.25 mol / L sulfuric acid (calculated as hydrogen ions) was introduced into the acid chamber of the second-stage cation exchange dialysis unit as the replacement medium. The linear velocity of the feed solution within the membrane stack in each chamber was 3 cm / s, and the temperature of the feed solution in each chamber was 38 °C. In the first stage, the initial glutamic acid fermentation broth and 300 mL of partially recovered ammonium salt acid solution (0.66 mol / L hydrogen ion concentration and 10.4 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit were subjected to first-stage cation exchange dialysis. When the glutamic acid supersolubility of the glutamic acid-to-acid feed solution obtained from the salt chamber of this stage cation exchange dialysis unit reached 2.0 (pH 4.80), crystallization was carried out. After crystallization in the storage tank for 30 min, the glutamic acid-to-acid feed solution containing glutamic acid crystals was returned to the circulating system. The solution was fed into the salt chamber of the first-stage cation exchange dialysis unit for further cation exchange dialysis. The resulting glutamic acid-to-acid feed solution had a pH of 5.0 and an ammonium ion concentration of 16.2 g / L. This solution was then subjected to a second-stage cation exchange dialysis with the initial acid solution. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid feed solution decreased to 4.76, and the solution was then passed into a heat exchange crystallizer. Crystallization was carried out at 10°C, and the glutamic acid crystals were separated by centrifugation, yielding glutamic acid crystals and 570 mL of desalted feed solution, thus ending the second stage. The glutamic acid recovery rate in the second stage was 33.2%, and the ammonium ion removal rate was 33%. 300 mL of ammonium nitrate with a concentration of 92.2 g / L was recovered in the first stage.

[0136] At the start of the third stage, the desalination solution obtained from the second stage, with a pH of 5.1, a glutamic acid concentration of 76.8 g / L, and an ammonium ion concentration of 10.9 g / L, is introduced into the salt chamber of the first-stage cation exchange dialysis unit. 300 mL of 1.07 mol / L sulfuric acid (calculated as hydrogen ions) is introduced into the acid chamber of the second-stage cation exchange dialysis unit as the replacement medium. The linear velocity of the solution within the membrane stack in each chamber is 3 cm / s, and the temperature of the solution in each chamber is 30 °C. In the first stage, the desalting solution is subjected to cation exchange dialysis with 300 mL of partially recovered ammonium salt acid solution (0.55 mol / L hydrogen ion concentration and 9.1 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit. When the supersolubility of the glutamic acid-to-acid solution obtained from the salt chamber of this stage of cation exchange dialysis unit reaches 2.0 (pH 4.32), crystallization is performed. After crystallization in the storage tank for 30 min, the glutamic acid-to-acid solution containing glutamic acid crystals is returned to the first-stage cation exchange dialysis unit. The ion-exchange dialysis unit's salt chamber continued cation-exchange dialysis. The first-stage cation-exchange dialysis unit's salt chamber yielded a glutamic acid-to-acid feed solution with a pH of 4.5 and an ammonium ion concentration of 4.6 g / L. This solution was then subjected to a second-stage cation-exchange dialysis with the initial acid solution. Cation-exchange dialysis was stopped when the pH of the glutamic acid-to-acid feed solution decreased to 3.0, and the solution was then passed into a heat exchange crystallizer for cooling and crystallization at 5°C. The glutamic acid crystals were separated by centrifugation, yielding glutamic acid crystals and 530 mL of unsalted glutamic acid isoelectric mother liquor, thus ending the third stage. The glutamic acid recovery rate in the third stage was 27.1%, and the ammonium ion removal rate was 28.1%. 300 mL of ammonium nitrate with a concentration of 80.8 g / L was recovered in the first stage.

[0137] The total glutamic acid yield was 95.2%, the ammonium ion removal rate was 96.1%, and the membrane flux was 2.9 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 1.9 g / L and a nitrate ion concentration of 8.2 g / L.

[0138] Example 15

[0139] Glutamic acid is extracted using a mixed three-stage countercurrent process, such as... Figure 9 As shown. The cation exchange dialysis apparatus is configured as three identical plate-type cation exchange dialysis membrane stacks, each stack being a single stage, and each stack being the same as in Example 1. Three heat exchange crystallizers are also configured, each heat exchange crystallizer being the same as in Example 1. The salt chambers of the three membrane stacks are each connected to one heat exchange crystallizer, and the acid chambers of the three membrane stacks are connected in series.

[0140] 300 mL of glutamic acid fermentation broth with a concentration of 100 g / L (calculated as glutamic acid) was introduced into the salt chamber of the first-stage cation exchange dialysis unit, and 300 mL of nitric acid with a concentration of 0.7 mol / L (calculated as hydrogen ions) was introduced into the acid chamber of the third-stage cation exchange dialysis unit as the replacement medium. The linear velocity of the feed solution in each chamber within the membrane stack was 7 cm / s.

[0141] In the first stage, the initial glutamic acid fermentation broth had a pH of 6.1 and an ammonium ion concentration of 15.6 g / L. This broth was mixed with 300 mL of partially recovered ammonium salt solution (0.2 mol / L hydrogen ion concentration and 9.2 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit. The first-stage cation exchange dialysis was performed, with the feed solution temperature in each chamber maintained at 60°C. When the pH of the glutamic acid-to-acid feed solution decreased to 4.81, the cation exchange dialysis was stopped. The glutamic acid-to-acid feed solution obtained from the first-stage salt chamber was then passed into a heat exchange crystallizer and cooled and crystallized at 5°C. The glutamic acid crystals were separated using a centrifuge, ending the first stage. The glutamic acid recovery rate in the first stage was 33.9%, and the ammonium ion removal rate was 32.5%.

[0142] 280 mL of the desalting solution obtained from the first stage (pH 5.0, ammonium ion concentration 7.9 g / L) was introduced into the salt chamber of the second-stage cation exchange dialysis unit. This solution, along with 300 mL of partially recovered ammonium salt solution (0.6 mol / L hydrogen ion concentration, 1.7 g / L ammonium ion concentration) recovered from the acid chamber of the third-stage cation exchange dialysis unit, underwent second-stage cation exchange dialysis. The temperature of the solutions in each chamber was maintained at 50°C. Cation exchange dialysis was stopped when the pH of the glutamic acid to acid solution decreased to 4.0. The glutamic acid to acid solution obtained from the second-stage salt chamber was then introduced into a heat exchange crystallizer under the same crystallization conditions as the first stage, thus ending the second stage. The glutamic acid recovery rate in the second stage was 51.1%, and the ammonium ion removal rate was 48.8%.

[0143] 263 mL of the desalting solution obtained from the second stage, with a pH of 4.56 and an ammonium ion concentration of 2.5 g / L, was introduced into the salt chamber of the third-stage cation exchange dialysis unit. This solution underwent third-stage cation exchange dialysis with the initial acid solution in the acid chamber of the third-stage cation exchange dialysis unit. The temperature of the solution in each chamber was 40 °C. Cation exchange dialysis was stopped when the pH of the glutamic acid to acid solution decreased to 3.2. The glutamic acid to acid solution obtained from the third-stage salt chamber was then introduced into a heat exchange crystallizer, and crystallization conditions were the same as in the first stage, thus ending the third stage. The glutamic acid recovery rate in the third stage was 8.7%, and the ammonium ion removal rate in the second stage was 12.2%.

[0144] The total glutamic acid yield was 93.7%, the ammonium ion removal rate was 93.5%, and the membrane flux was 2.6 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 1.1 g / L and a nitrate concentration of 1.1 g / L. Ammonium nitrate was recovered to 62.4 g / L in the acid chamber of the first-stage cation exchange dialysis unit.

[0145] Example 16

[0146] Glutamic acid is extracted using a mixed six-stage countercurrent process, such as... Figure 14 As shown. The cation exchange dialysis apparatus is configured with six identical plate-type cation exchange dialysis membrane stacks, each stack being a single stage, and each stack being the same as in Example 1. Six heat exchange crystallizers are also configured, each heat exchange crystallizer being the same as in Example 1. The salt chambers of the six membrane stacks are each connected to one heat exchange crystallizer, and the acid chambers of the six membrane stacks are connected in series.

[0147] 295 mL of glutamic acid fermentation broth with a concentration of 193 g / L (calculated as glutamic acid) was introduced into the salt chamber of the first-stage cation exchange dialysis unit, and 295 mL of sulfuric acid with a concentration of 1.8 mol / L (calculated as hydrogen ions) was introduced into the acid chamber of the sixth-stage cation exchange dialysis unit as the replacement medium. The linear velocity of the feed solution in each chamber within the membrane stack was 0.5 cm / s, and the temperature of the feed solution in each chamber was 60 °C.

[0148] In the first stage, the initial glutamic acid fermentation broth had a pH of 6.1 and an ammonium ion concentration of 27.8 g / L. This broth was mixed with 295 mL of partially recovered ammonium salt solution (0.7 mol / L hydrogen ion concentration and 19.1 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit for first-stage cation exchange dialysis. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid feed solution decreased to 4.9. The glutamic acid-to-acid feed solution obtained from the first-stage salt chamber was then passed into a heat exchange crystallizer for cooling and crystallization at 5°C. The glutamic acid crystals were separated using a centrifuge, ending the first stage. The glutamic acid recovery rate in the first stage was 13.4%, and the ammonium ion removal rate was 16.2%.

[0149] 295 mL of the desalting solution obtained from the first stage (pH 5.4, ammonium ion concentration 22.7 g / L) was passed into the salt chamber of the second-stage cation exchange dialysis unit. This solution, along with 295 mL of partially recovered ammonium salt solution (hydrogen ion concentration 1.0 mol / L, ammonium ion concentration 14.9 g / L) recovered from the acid chamber of the third-stage cation exchange dialysis unit, underwent the second-stage cation exchange dialysis. Cation exchange dialysis was stopped when the pH of the glutamic acid to acid solution decreased to 4.7. The glutamic acid to acid solution obtained from the second-stage salt chamber was then passed into a heat exchange crystallizer under the same crystallization conditions as the first stage, thus ending the second stage. The glutamic acid recovery rate in the second stage was 21%, and the ammonium ion removal rate was 20%.

[0150] 290 mL of the desalting solution obtained from the second stage (pH 5.3, ammonium ion concentration 18.6 g / L) was passed into the salt chamber of the third-stage cation exchange dialysis unit. This solution, along with 295 mL of partially recovered ammonium salt acid solution (hydrogen ion concentration 1.2 mol / L, ammonium ion concentration 10.5 g / L) recovered from the acid chamber of the fourth-stage cation exchange dialysis unit, underwent third-stage cation exchange dialysis. Cation exchange dialysis was stopped when the pH of the glutamic acid to acid solution decreased to 4.5. The glutamic acid to acid solution obtained from the third-stage salt chamber was then passed into a heat exchange crystallizer under the same crystallization conditions as the first stage, thus ending the third stage. The glutamic acid recovery rate in the third stage was 23.7%, and the ammonium ion removal rate was 20%.

[0151] 285 mL of the desalting solution obtained from the third stage (pH 5.1, ammonium ion concentration 1.25 g / L) was introduced into the salt chamber of the fourth-stage cation exchange dialysis unit. This solution, along with 295 mL of partially recovered ammonium salt solution (hydrogen ion concentration 1.4 mol / L, ammonium ion concentration 6.9 g / L) recovered from the acid chamber of the fifth-stage cation exchange dialysis unit, underwent fourth-stage cation exchange dialysis. Cation exchange dialysis was stopped when the pH of the glutamic acid to acid solution decreased to 4.1. The glutamic acid to acid solution obtained from the fourth-stage salt chamber was then introduced into a heat exchange crystallizer under the same crystallization conditions as the first stage, thus ending the fourth stage. The glutamic acid recovery rate in the fourth stage was 17.4%, and the ammonium ion removal rate was 14.4%.

[0152] 285 mL of the desalting solution obtained from the fourth stage (pH 4.9, ammonium ion concentration 8.3 g / L) was passed into the salt chamber of the fifth-stage cation exchange dialysis unit. This solution, along with 295 mL of partially recovered ammonium salt solution (hydrogen ion concentration 1.5 mol / L, ammonium ion concentration 5.9 g / L) recovered from the acid chamber of the sixth-stage cation exchange dialysis unit, underwent fifth-stage cation exchange dialysis. Cation exchange dialysis was stopped when the pH of the glutamic acid to acid solution decreased to 4.4. The glutamic acid to acid solution obtained from the fifth-stage salt chamber was then passed into a heat exchange crystallizer under the same crystallization conditions as the first stage, thus ending the fifth stage. The glutamic acid recovery rate in the fifth stage was 7.8%, and the ammonium ion removal rate was 4.6%.

[0153] 280 mL of the desalting solution obtained from the fifth stage, with a pH of 4.8 and an ammonium ion concentration of 7.1 g / L, was passed into the salt chamber of the sixth-stage cation exchange dialysis unit, where it underwent sixth-stage cation exchange dialysis with the initial acid solution in the acid chamber. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid solution decreased to 3.3. The glutamic acid-to-acid solution obtained from the sixth-stage salt chamber was then passed into a heat exchange crystallizer, and crystallization conditions were the same as in the first stage, thus ending the sixth stage. The glutamic acid recovery rate in the sixth stage was 12.2%, and the ammonium ion removal rate was 16.3%.

[0154] The total glutamic acid yield was 95.4%, the ammonium ion removal rate was 91.6%, and the membrane flux was 2.8 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 3.9 g / L and a sulfate concentration of 3.3 g / L. Ammonium sulfate was recovered to 91.7 g / L in the acid chamber of the first-stage cation exchange dialysis unit.

[0155] Example 17

[0156] Glutamic acid is extracted using a mixed four-stage countercurrent process, such as... Figure 15 As shown. The cation exchange dialysis apparatus is configured with four identical plate-type cation exchange dialysis membrane stacks, each stack being a single stage, and each stack being the same as in Example 3. Four heat exchange crystallizers are provided, each heat exchange crystallizer being the same as in Example 1. The salt chambers of the four membrane stacks are each connected to one heat exchange crystallizer, and the acid chambers of the four membrane stacks are connected in series. The storage tank for glutamic acid crystal growth is the same as in Example 2.

[0157] 380 mL of glutamic acid fermentation broth with a concentration of 250 g / L (calculated as glutamic acid) was introduced into the salt chamber of the first-stage cation exchange dialysis unit, and 406 mL of hydrochloric acid with a concentration of 1.9 mol / L (calculated as hydrogen ions) was introduced into the acid chamber of the fourth-stage cation exchange dialysis unit as the replacement medium. The linear velocity of the feed solution in each chamber within the membrane stack was 4 cm / s.

[0158] In the first stage, the initial glutamic acid fermentation broth had a pH of 6.3 and an ammonium ion concentration of 28.5 g / L. This broth was then subjected to first-stage cation exchange dialysis with 400 mL of partially recovered ammonium salt solution (0.11 mol / L hydrogen ion concentration and 20.4 g / L ammonium ion concentration) recovered from the acid chamber of the second-stage cation exchange dialysis unit. The temperature of the feed solution in each chamber was 60℃. When the glutamic acid supersolubility in the glutamic acid-to-acid feed solution obtained from the salt chamber of this stage's cation exchange dialysis unit reached 1.5 (pH 5.1), crystallization was initiated. The glutamic acid-to-acid feed solution was transferred to a storage tank with 8% seed crystals added. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid feed solution containing glutamic acid crystals was returned to the salt chamber of the first-stage cation exchange dialysis unit for continued cation exchange dialysis. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid feed solution decreased to 5.07. The glutamic acid-to-acid feed solution obtained from the first-stage salt chamber was fed into a heat exchange crystallizer and cooled and crystallized at 5°C. The glutamic acid crystals were then separated using a centrifuge, thus ending the first stage. The glutamic acid recovery rate for the first stage was 20.8%, and the ammonium ion removal rate for the first stage was 22.8%.

[0159] 372 mL of the desalting solution obtained from the first stage (pH 5.7, ammonium ion concentration 22.8 g / L) was introduced into the salt chamber of the second-stage cation exchange dialysis unit. This solution, along with 400 mL of partially recovered ammonium salt solution (0.5 mol / L hydrogen ion concentration, 13.5 g / L ammonium ion concentration) recovered from the acid chamber of the third-stage cation exchange dialysis unit, underwent second-stage cation exchange dialysis. The temperature of the solutions in each chamber was 55°C. When the supersolubility of glutamic acid in the glutamic acid-to-acid solution obtained from the salt chamber of this stage of the cation exchange dialysis unit reached 1.5 (pH 4.74), crystallization was initiated. The glutamic acid-to-acid solution was transferred to a storage tank with 8% seed crystals added. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid solution containing glutamic acid crystals was returned to the salt chamber of the second-stage cation exchange dialysis unit for continued cation exchange dialysis. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid solution decreased to 4.8. The glutamic acid-to-acid feed solution obtained from the second-stage salt chamber was fed into a heat exchange crystallizer under the same crystallization conditions as the first stage, thus ending the second stage. The glutamic acid recovery rate in the second stage was 22.1%, and the ammonium ion removal rate in the second stage was 24.4%.

[0160] 365 mL of the desalting solution obtained in the second stage, with a pH of 5.7 and an ammonium ion concentration of 15.8 g / L, was introduced into the salt chamber of the third-stage cation exchange dialysis unit. This solution, along with 396 mL of partially recovered ammonium salt acid solution with a hydrogen ion concentration of 0.85 mol / L and an ammonium ion concentration of 7.5 g / L, was then used for the third-stage cation exchange dialysis. The temperature of the solution in each chamber was 45 °C. When the supersolubility of glutamic acid in the glutamic acid-to-acid feed solution obtained from the salt chamber of the first-stage cation exchange dialysis unit reaches 1.5 (pH 4.7), crystallization is initiated. The glutamic acid-to-acid feed solution is transferred to a storage tank with 8% seed crystals added. After crystallization in the storage tank for 30 minutes, the glutamic acid-to-acid feed solution containing glutamic acid crystals is returned to the salt chamber of the third-stage cation exchange dialysis unit for continued cation exchange dialysis. When the pH of the glutamic acid-to-acid feed solution decreases to 4.55, cation exchange dialysis is stopped. The glutamic acid-to-acid feed solution obtained from the third-stage salt chamber is then passed into a heat exchange crystallizer under the same crystallization conditions as the first stage, thus ending the third stage. The glutamic acid recovery rate in the third stage is 23%, and the ammonium ion removal rate in the third stage is 21.9%.

[0161] 350 mL of the desalination solution obtained from the third stage (pH 5.4, ammonium ion concentration 10.1 g / L) was introduced into the salt chamber of the fourth-stage cation exchange dialysis unit for fourth-stage cation exchange dialysis with the initial acid solution. The temperature of the solution in each chamber was 35℃. When the supersolubility of glutamic acid in the glutamic acid-to-acid solution obtained from the salt chamber of this stage of the cation exchange dialysis unit reached 1.5 (pH 4.2), crystallization was initiated. The glutamic acid-to-acid solution was transferred to a storage tank with 8% seed crystals added. After crystallization in the storage tank for 30 min, the glutamic acid-to-acid solution containing glutamic acid crystals was returned to the salt chamber of the fourth-stage cation exchange dialysis unit for continued cation exchange dialysis. Cation exchange dialysis was stopped when the pH of the glutamic acid-to-acid solution decreased to 3.0. The glutamic acid-to-acid solution obtained from the fourth-stage salt chamber was introduced into a heat exchange crystallizer under the same crystallization conditions as the first stage, thus ending the fourth stage. The glutamic acid recovery rate in the fourth stage was 27.4%, and the ammonium ion removal rate in the third stage was 27.4%.

[0162] The total glutamic acid yield was 93.3%, the ammonium ion removal rate was 92.8%, and the membrane flux was 3.2 mol / m³. 2 / h. The final salt-free mother liquor had an ammonium ion concentration of 2.4 g / L and a chloride ion concentration of 5.5 g / L. Ammonium chloride was recovered to 61.2 g / L in the acid chamber of the first-stage cation exchange dialysis unit.

[0163] Comparative Example 1

[0164] Glutamic acid was extracted using isoelectric crystallization by directly adding acid to the glutamic acid fermentation broth. 300 mL of glutamic acid fermentation broth (180 g / L concentration, calculated as glutamic acid) was taken, and 4.26 mol / L sulfuric acid solution was added over 30 min. Acid addition was stopped when the pH of the glutamic acid fermentation broth reached 4.8. 8% seed crystals were added for crystallization for 30 min, and then 4.26 mol / L sulfuric acid solution was added at a uniform rate over 180 min until the pH reached 3.2. Crystallization was carried out at 5 °C, and the glutamic acid crystals were separated by centrifugation. Glutamic acid crystals and 343 mL of isoelectric mother liquor containing salt glutamic acid were obtained.

[0165] The glutamic acid recovery rate was 87.6%, which was 4.5% lower than the method used in Example 6 for treating the same glutamic acid fermentation broth. The isoelectric mother liquor containing salt glutamic acid obtained in this comparative example had an ammonium sulfate concentration of 70.7 g / L, which contained impurities such as amino acids, polysaccharides, proteins, and pigments, making it difficult to process and utilize. In contrast, the salt-free mother liquor and high-purity ammonium sulfate obtained in Example 6 are easier to process and utilize, thus increasing the added value of the by-products.

[0166] All aspects not described in detail in this invention can be covered using conventional technical knowledge in the field.

[0167] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for directly extracting glutamic acid from glutamic acid fermentation broth using cation exchange dialysis, comprising the following steps: (1) Cation exchange dialysis: The glutamic acid fermentation broth is passed into a cation exchange dialysis device and subjected to cation exchange dialysis with an acid solution to obtain glutamic acid-to-acid feed solution and ammonium salt. The main component of the glutamic acid fermentation broth is ammonium glutamic acid. (2) Glutamic acid crystallization: The glutamic acid-converting solution obtained in step (1) is crystallized, and the glutamic acid crystals are separated to obtain glutamic acid crystals and salt-free solution; In step (1), the cation exchange dialysis device includes one cation exchange dialysis component or multiple cation exchange dialysis components connected in series and / or in parallel. The cation exchange dialysis component includes a cation exchange dialysis membrane and a salt chamber and an acid chamber separated by the cation exchange dialysis membrane. The glutamic acid fermentation broth is passed into the salt chamber, and the acid solution is passed into the acid chamber as a replacement medium. The glutamic acid-to-acid feed solution is obtained in the salt chamber, and the ammonium salt corresponding to the acid solution is obtained in the acid chamber.

2. The method according to claim 1, characterized in that, When the supersolubility of glutamic acid in the glutamic acid-to-acid solution in the salt chamber of the cation exchange dialysis device in step (1) reaches 1.4-2, the glutamic acid-to-acid solution is transferred to the storage tank and seed crystals are added. After crystallization in the storage tank, the glutamic acid-to-acid solution with glutamic acid crystals is returned to the salt chamber of the cation exchange dialysis device to continue the cation exchange dialysis in step (1) until the pH of the glutamic acid-to-acid solution obtained in the salt chamber of the cation exchange dialysis device decreases to 3.0-3.

3.

3. The method according to claim 1, characterized in that, The number of the plurality of cation exchange dialysis components is two, three, four, five, or six.

4. The method according to claim 1, characterized in that, The cation exchange dialysis module is a plate-and-frame cation exchange dialysis membrane stack, a tubular cation exchange dialysis membrane module, or a spiral wound cation exchange dialysis membrane module.

5. The method according to claim 1, characterized in that, In step (1), the acid solution includes any one or a combination of at least two of hydrochloric acid, nitric acid and sulfuric acid, and the initial molar concentration of the acid solution is 0.4-2.0 mol / L, calculated as hydrogen ions.

6. The method according to claim 1, characterized in that, The initial concentration of the glutamic acid fermentation broth in step (1), calculated as glutamic acid, is 60-100 g / L.

7. The method according to any one of claims 1-5, characterized in that, The method adopts a multi-segment processing approach, which involves repeating steps (1) and (2) multiple times. Each completion of steps (1) and (2) is called a segment. The glutamic acid-converting solution obtained from the salt chamber of the cation exchange dialysis device in step (1) is cooled and crystallized. After separating the glutamic acid crystals, a desalted solution is obtained, thus ending the first stage. The desalted solution obtained in the first stage is then used as the feed solution for the salt chamber of the cation exchange dialysis device in step (1) to start the next stage of cation exchange dialysis treatment, and the above process is repeated.

8. The method according to claim 7, characterized in that, In the multi-stage treatment method, the operating temperature of the cation exchange dialysis treatment in each stage (1) is 20-60℃, and the operating temperature of the cation exchange dialysis treatment decreases step by step as the number of treatment stages increases; the basis for the end of step (1) of each stage is that the concentration of glutamic acid crystals in the glutamic acid conversion solution in the salt chamber of the cation exchange dialysis device does not exceed 70g / L. Based on glutamic acid, the initial concentration of the glutamic acid fermentation broth in the multi-stage treatment method is 100-250 g / L.

9. The method according to any one of claims 1-6, characterized in that, The cation exchange dialysis treatment adopts a multi-stage countercurrent treatment method; the multi-stage countercurrent treatment method is to set the cation exchange dialysis device into multiple cation exchange dialysis components, each cation exchange dialysis component is a stage, including a cation exchange dialysis membrane and salt chambers and acid chambers separated by the cation exchange dialysis membrane, and the salt chambers of multiple stages of cation exchange dialysis components are connected in series, and the acid chambers of multiple stages of cation exchange dialysis components are connected in series. The initial glutamic acid fermentation broth is passed into the salt chamber of the first-stage cation exchange dialysis unit, and the initial acid solution is passed into the acid chamber of the last-stage cation exchange dialysis unit. The glutamic acid-to-acid feed solution is obtained in the salt chamber of the last-stage cation exchange dialysis unit, and the ammonium salt is obtained in the acid chamber of the first-stage cation exchange dialysis unit.

10. The method according to any one of claims 1-5, characterized in that, The method employs a multi-stage, multi-level processing approach, which involves repeatedly performing steps (1) and (2). Each completion of steps (1) and (2) is referred to as a stage. The glutamic acid-converting feed solution obtained from the salt chamber of the cation exchange dialysis device in step (1) is fed into the heat exchange crystallizer in step (2) for cooling and crystallization. After separating the glutamic acid crystals, a desalted feed solution is obtained, thus ending the first stage. The desalted feed solution obtained from the first stage is then used as the feed solution for the salt chamber of the cation exchange dialysis device in step (1) to begin the next stage of cation exchange dialysis treatment, and the above process is repeated. In step (1), the cation exchange dialysis treatment adopts a multi-stage countercurrent treatment method. That is, the cation exchange dialysis device is set up as multiple cation exchange dialysis components. Each cation exchange dialysis component is a stage, including a cation exchange dialysis membrane and a salt chamber and an acid chamber separated by the cation exchange dialysis membrane. The salt chambers of multiple stages of cation exchange dialysis components are connected in series, and the acid chambers of multiple stages of cation exchange dialysis components are connected in series. The initial glutamic acid fermentation broth is passed into the salt chamber of the first stage cation exchange dialysis component, and the initial acid solution is passed into the acid chamber of the last stage cation exchange dialysis component. The glutamic acid-to-acid feed solution is obtained in the salt chamber of the last stage cation exchange dialysis component, and the ammonium salt is obtained in the acid chamber of the first stage cation exchange dialysis component.

11. The method according to claim 10, characterized in that, In the multi-stage multi-processing method, the operating temperature of the cation exchange dialysis treatment in each stage (1) is 20-60℃, and the operating temperature of the cation exchange dialysis treatment decreases step by step as the number of treatment stages increases; the basis for the end of step (1) of each stage is that the concentration of glutamic acid crystals in the glutamic acid conversion solution in the salt chamber of the cation exchange dialysis device does not exceed 70g / L. The initial glutamic acid fermentation broth concentration in the multi-stage, multi-level treatment method is 100-250 g / L, calculated as glutamic acid.

12. The method according to any one of claims 1-5, characterized in that, The method employs a hybrid multi-segment, multi-level processing approach, which is as follows: The cation exchange dialysis device in step (1) is configured as multiple cation exchange dialysis components. Each cation exchange dialysis component is a stage, including a cation exchange dialysis membrane and a salt chamber and an acid chamber separated by the cation exchange dialysis membrane. The salt chambers of each stage of the cation exchange dialysis component are connected to the heat exchange crystallizer in step (2), and the acid chambers of each stage of the cation exchange dialysis component are connected in series. The initial glutamic acid fermentation broth is fed into the salt chamber of the first-stage cation exchange dialysis unit, and the initial acid solution is fed into the acid chamber of the last-stage cation exchange dialysis unit. The acid solution from each stage of acid chamber, which contains a portion of the recovered ammonium salt, is fed into the acid chamber of the previous stage. The glutamic acid-to-acid feed solution obtained from the salt chamber of each stage of cation exchange dialysis unit in step (1) is fed into the heat exchange crystallizer in step (2) connected to it, completing one step (2), which is called a segment. The desalted feed solution obtained after separating glutamic acid crystals in the previous segment (2) is fed into the salt chamber of this stage of cation exchange dialysis unit, and the resulting glutamic acid-to-acid feed solution is fed into the heat exchange crystallizer in step (2) of this segment, completing one step (2) and ending this segment. Ammonium salt is obtained in the acid chamber of the first-stage cation exchange dialysis unit, and glutamic acid-to-acid feed solution is obtained in the salt chamber of the last-stage cation exchange dialysis unit. The feed solution is fed into the heat exchange crystallizer of the last segment to obtain glutamic acid crystals and desalted feed solution. After separating the glutamic acid crystals, a salt-free mother liquor is obtained.

13. The method according to claim 12, characterized in that, In the mixed multi-stage multi-processing method, the operating temperature of the cation exchange dialysis treatment in each stage (1) is 20-60℃, and the operating temperature of the cation exchange dialysis treatment decreases step by step as the number of treatment stages increases; the basis for segmentation is that the concentration of glutamic acid crystals in the glutamic acid to acid feed solution in the salt chamber of each stage of the cation exchange dialysis component does not exceed 70g / L. The initial glutamic acid fermentation broth concentration in the mixed multi-stage treatment method is 100-250 g / L, calculated as glutamic acid.

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