A stepwise centrifugation and isoelectric crystallization process for glutamic acid purification

Abstract

This invention discloses a stepwise centrifugation and isoelectric crystallization process for glutamic acid purification, belonging to the field of amino acid extraction and purification technology. Addressing the problems of low solid-liquid separation efficiency, insufficient yield, and limited purity in traditional processes, this process comprises four core steps: pretreatment centrifugation, isoelectric point crystallization, secondary purification centrifugation, and post-treatment. Solid impurities are removed through precise temperature-controlled centrifugation; precise isoelectric point control combined with gradient cooling and seed induction achieves efficient crystallization of dissolved glutamic acid; secondary high-speed centrifugation provides deep purification; and washing and post-treatment ensure quality. This process increases the glutamic acid yield to over 87.31% and the purity to over 98.38%, with low modification costs, energy consumption, environmental friendliness, and strong equipment compatibility, making it suitable for large-scale industrial production and meeting the needs of high-end food and pharmaceutical fields.

Description

Technical Field

[0001] This invention relates to the field of amino acid extraction and purification technology, specifically a glutamic acid purification process using stepwise centrifugation and isoelectric crystallization. Background Technology

[0002] Glutamic acid, as a basic building block of proteins, is a core raw material for flavor enhancers in the food industry, pharmaceutical infusion raw materials, and precursors in biochemical synthesis. Market demand is robust, with high-purity glutamic acid (purity ≥97%) experiencing continuous growth in demand in high-end applications. Currently, industrial production of glutamic acid primarily relies on fermentation. The core process involves saccharification and fermentation of starchy raw materials to obtain a fermentation broth, followed by separation and purification to obtain crystalline products. The separation and purification process directly determines product yield, purity, and production costs, making it crucial for a company's core competitiveness.

[0003] Traditional glutamic acid purification processes mainly rely on "single isoelectric crystallization + plate and frame filtration or membrane separation," supplemented by simple centrifugation. This approach suffers from several intractable technical challenges: First, solid-liquid separation efficiency is low, as impurities such as bacteria, proteins, and colloids in the fermentation broth mix with the glutamic acid crystals. Second, yield is low; traditional isoelectric crystallization only precipitates a portion of the glutamic acid, with a large amount of dissolved glutamic acid lost with the waste liquid. Actual glutamic acid yield is only about 86.24%, resulting in significant resource waste. Third, purity is insufficient; impurities easily co-crystallize with the crystals or adsorb onto the surface, and the accuracy of manual pH control is low, resulting in a product purity of only 96.95%, which is insufficient to meet the demands of high-end applications. Fourth, energy consumption and environmental pressure are high; plate and frame filtration consumes a large amount of water, and the treatment cost of high-concentration organic wastewater is high.

[0004] To address these issues, the industry has attempted various improvement solutions, but all have significant limitations: membrane separation technology offers high separation precision, but membrane modules are expensive, prone to clogging, and have short lifespans, resulting in high overall costs; multiple isoelectric crystallization processes can improve purity, but the process is cumbersome and time-consuming, leading to a decrease in yield; solvent extraction can easily leave organic solvent residues, which do not meet the requirements for food-grade production; upgrading centrifuge equipment alone lacks synergistic design with the crystallization process, resulting in limited yield improvement and high modification costs.

[0005] In summary, existing processes suffer from low solid-liquid separation efficiency, insufficient yield, limited purity, high energy consumption, and significant environmental impact. Furthermore, current improvement schemes cannot simultaneously achieve multi-dimensional optimization while controlling costs. Therefore, developing a purification process that is simple, highly compatible with equipment, has low modification costs, and can simultaneously improve the yield and purity of glutamic acid has become a pressing technical challenge for the industry, and is of great significance for promoting technological upgrades and reducing production costs. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a stepwise centrifugation and isoelectric crystallization process for glutamic acid purification, which achieves efficient solid-liquid separation of glutamic acid fermentation broth, full recovery of dissolved glutamic acid, and improves product yield and purity. The process is simple, has strong equipment compatibility, and low modification cost.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A stepwise centrifugation and isoelectric crystallization process for purifying glutamic acid includes the following steps:

[0009] S1, Pretreatment centrifugation: After adjusting the temperature of the glutamic acid crystallization fermentation broth to 20-30℃, solid-liquid separation is carried out to remove solid impurities such as bacterial cells, proteins, and colloids in the fermentation broth. At the same time, the initial glutamic acid crystals that have precipitated in the fermentation broth are extracted to obtain preliminary crystal products and clear liquid containing dissolved glutamic acid.

[0010] S2, Isoelectric point crystallization: The clear liquid is introduced into the isoelectric crystallization tank, the stirring device is turned on, and the pH value of the clear liquid is adjusted to the isoelectric point of glutamic acid. Then, the temperature is gradually reduced, and the liquid is kept at a constant temperature to allow the dissolved glutamic acid to fully crystallize and precipitate, forming a secondary crystallization liquid.

[0011] S3, Secondary purification centrifugation: The secondary crystallization liquid obtained in step S2 is subjected to secondary solid-liquid separation at a speed higher than that of the pretreatment centrifugation to obtain high-purity glutamic acid crystals;

[0012] S4, Post-processing: Wash the high-purity glutamic acid crystals obtained from the second centrifugation to obtain the final glutamic acid.

[0013] Furthermore, in step S1, the glutamic acid concentration of the glutamic acid crystallization fermentation broth is 80-120 g / L, and the temperature is controlled using a plate heat exchanger with a temperature control accuracy of ±0.5℃. Solid-liquid separation is performed using a horizontal spiral sedimentation centrifuge or a disc centrifuge at a speed of 3000-5000 r / min for 15-30 min, with the feed rate controlled at 10-20 m / s during centrifugation. 3 / h.

[0014] Furthermore, the selection of centrifuge equipment in step S1 is based on the production line capacity: when the daily production capacity of the production line is ≤50 tons, a disc centrifuge is selected; when the daily production capacity of the production line is >50 tons, a horizontal spiral sedimentation centrifuge is selected; the differential speed control of the centrifuge equipment is 20-50 r / min.

[0015] Furthermore, the isoelectric point of glutamic acid mentioned in step S2 is pH 3.2-3.4. The pH is adjusted using concentrated sulfuric acid at a rate of 0.4 / h, and the stirring speed is 30 r / min during the pH adjustment process. The gradient cooling process is as follows: first, the temperature of the clear liquid is reduced from 20-30℃ to 15-20℃ at a rate of 3℃ / h and kept at this temperature for 2-3 h, and then reduced to 8-12℃ at a rate of 3℃ / h and kept at this temperature for 4-6 h. The total settling time is 6-9 h.

[0016] Furthermore, the secondary centrifuge equipment mentioned in step S3 is of the same type as the pretreatment centrifuge equipment, with a centrifugation speed of 4000-6000 r / min, a centrifugation time of 20-40 min, and a feed rate of 8-15 m. 3 / h.

[0017] Furthermore, in step S4, deionized water is used for washing for 15-20 minutes, and the amount of washing solution is 1.5-2.0 times the mass of the crystals.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) This invention achieves efficient recovery of glutamic acid through a synergistic process design of "centrifugation + isoelectric point + centrifugation". The glutamic acid yield is increased from about 86.24% in the traditional process to more than 87.31%, an increase of more than 1.07%. Taking a production line with a daily output of 50 tons as an example, about 0.535 tons of glutamic acid can be recovered daily, resulting in a significant increase in annual output value and a substantial improvement in resource utilization.

[0020] (2) This invention uses a multi-stage purification design to remove most solid impurities through pretreatment centrifugation, secondary refining centrifugation to remove surface impurities, and washing to remove soluble impurities. The product purity is increased from 96.95% in the traditional process to more than 98.38%, an increase of more than 1.43%, which meets the application requirements of high-end food and pharmaceutical fields and significantly improves the added value of the product.

[0021] (3) The centrifuges, isoelectric crystallizers and other equipment used in this invention are all conventional equipment in the industry. No special equipment needs to be customized. They can be directly upgraded and modified on existing glutamic acid production lines, which is convenient for large-scale promotion and application in the industry.

[0022] (4) The present invention does not require heating and concentration pretreatment, thus avoiding the high energy consumption problem of traditional processes; at the same time, the increased yield reduces raw material waste. Detailed Implementation

[0023] The present invention will be further described below with reference to the embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments.

[0024] Example 1

[0025] This embodiment provides a stepwise centrifugation and isoelectric crystallization process for glutamic acid purification, the specific steps of which are as follows:

[0026] Pretreatment centrifugation: 100 mL of crystalline fermentation broth with a glutamic acid concentration of 95 g / L was selected. 3 The temperature was adjusted to 25℃ (temperature control accuracy ±0.5℃) via a plate heat exchanger and then fed into a disc centrifuge (model: DPF550). The centrifugal speed was set to 3800 r / min, the differential speed to 30 r / min, and the feed rate to 12 m. 3 The centrifugation time was 22 min / h. After centrifugation, 23.8 tons of preliminary crystalline product and 76.2 ml of supernatant were obtained. 3 The test results showed that the solid impurity removal rate was 95.6% and the crystal loss rate was ≤0.3%.

[0027] Isoelectric point crystallization: Pass the clear liquid through a 100 m... 3 In the isoelectric crystallization tank, the anchor-type stirrer was turned on and the stirring speed was set to 30 r / min. Then, 98% concentrated sulfuric acid was added dropwise to adjust the pH of the clarified solution to 3.3 (the isoelectric point of glutamic acid), with a pH reduction rate of 0.4 / h. After adjustment, the jacketed heat exchanger was activated for gradient cooling: first, the temperature was reduced from 25℃ to 18℃ at a rate of 3℃ / h and held for 2.5 h; then, it was reduced to 10℃ at a rate of 3℃ / h and held for 5 h, for a total settling time of 7.5 h, forming a secondary crystallization solution.

[0028] Secondary purification centrifugation: The secondary crystallization solution was fed into the same disc centrifuge, and the centrifugation speed was adjusted to 4800 r / min, the differential speed to 25 r / min, and the feed rate to 10 m. 3 The centrifugation time was 30 min / h, and the pressure inside the drum was controlled at 0.15 MPa during the centrifugation process. 2.6 tons of high-purity glutamic acid crystals were obtained after centrifugation, and the residual impurity content of the crystals was found to be 0.42%.

[0029] Post-processing: The crystals obtained from the second centrifugation were sent to a washing device and washed with deionized water for 18 minutes. The amount of washing solution was 1.8 times the mass of the crystals, thus obtaining high-purity glutamic acid.

[0030] According to tests conducted by a third-party testing agency, the glutamic acid yield of the finished product is 87.28%, the purity is 98.35%, and the particle size uniformity is ≥95%. All indicators meet the superior grade standard of GB / T8967-2007 "Monosodium Glutamate (MSG)" and satisfy the purity requirements of pharmaceutical-grade glutamic acid.

[0031] Example 2

[0032] The stepwise centrifugation and isoelectric crystallization process for glutamic acid purification provided in this embodiment includes the following specific steps:

[0033] Pretreatment centrifugation: 200 mL of crystalline fermentation broth with a glutamic acid concentration of 110 g / L was selected. 3 The temperature was adjusted to 28℃ (temperature control accuracy ±0.5℃) via a plate heat exchanger and then fed into a horizontal spiral sedimentation centrifuge (model: LW650×2200). The centrifugal speed was set to 4500 r / min, the differential speed to 40 r / min, and the feed rate to 18 m. 3 The centrifugation time was 28 min at a time, with a centrifugation rate of / h. After centrifugation, 52.3 tons of preliminary crystalline product and 147.7 m³ of supernatant were obtained. 3 The test results showed that the solid impurity removal rate was 96.1% and the crystal loss rate was ≤0.25%.

[0034] Isoelectric point crystallization: Pass the clear liquid through a 200 m... 3 In the isoelectric crystallizer, the anchor-type stirrer was turned on and the stirring speed was set to 30 r / min. Then, 98% concentrated sulfuric acid was added dropwise to adjust the pH of the clarified solution to 3.35 (the isoelectric point of glutamic acid), with a pH reduction rate of 0.4 / h. After adjustment, the jacketed heat exchanger was activated for gradient cooling: first, the temperature was reduced from 28℃ to 20℃ at a rate of 3℃ / h and held for 3 h; then, it was reduced to 12℃ at a rate of 3℃ / h and held for 4.5 h, for a total settling time of 7.5 h, forming a secondary crystallizer.

[0035] Secondary purification centrifugation: The secondary crystallization solution was fed into the same horizontal screw sedimentation centrifuge, and the centrifugal speed was adjusted to 5500 r / min, the differential speed to 30 r / min, and the feed rate to 14 m. 3 The centrifugation time was 35 min / h, and the pressure inside the drum was controlled at 0.18 MPa during the centrifugation process. After centrifugation, 6.2 tons of high-purity glutamic acid crystals were obtained. Testing showed that the residual impurity content in the crystals was 0.38%.

[0036] Post-processing: The crystals obtained from the second centrifugation were sent to a washing device and washed with deionized water for 20 minutes. The amount of washing solution was 1.9 times the mass of the crystals, thus obtaining high-purity glutamic acid.

[0037] The product was tested and found to have a glutamic acid yield of 87.36%, a purity of 98.42%, and a particle size uniformity of ≥96%. All indicators are superior to industry standards and it can be directly used for the production of high-end monosodium glutamate and as a raw material for pharmaceutical infusions.

[0038] Example 3

[0039] To verify the technical advantages of this invention, comparative experiments were conducted on the same production line using the process provided by this invention and the traditional process, respectively. The experimental conditions are as follows:

[0040] Experimental materials: glutamic acid fermentation broth from the same batch, with a glutamic acid concentration of 100 g / L and a total volume of 20 mg / L. 3 ;

[0041] Traditional process: "Heating pretreatment (70℃, 30 min) + isoelectric crystallization (pH 3.2-3.4, natural cooling, standing for 12 h) + plate and frame filtration + single washing + drying";

[0042] The process of this invention adopts the process parameters of Example 1.

[0043] The results of the comparative experiment are shown in the table below:

[0044]

[0045] The comparative experimental results show that the process provided by this invention is significantly superior to traditional processes in terms of yield, purity, production efficiency, energy consumption, and environmental protection. It has outstanding technical advantages and strong industrial application value.

[0046] The above embodiments are merely one of the preferred embodiments of the present invention and should not be used to limit the scope of protection of the present invention. Any modifications or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but solve the same technical problem as the present invention, should be included within the scope of protection of the present invention.

Claims

1. A stepwise centrifugation and isoelectric crystallization process for glutamic acid purification, characterized in that, Includes the following steps: S1, Pretreatment centrifugation: After adjusting the temperature of the glutamic acid crystallization fermentation broth to 20-30℃, solid-liquid separation is carried out to remove solid impurities such as bacterial cells, proteins, and colloids in the fermentation broth. At the same time, the initial glutamic acid crystals that have precipitated in the fermentation broth are extracted to obtain preliminary crystal products and clear liquid containing dissolved glutamic acid. S2, Isoelectric point crystallization: The clear liquid is introduced into the isoelectric crystallization tank, the stirring device is turned on, and the pH value of the clear liquid is adjusted to the isoelectric point of glutamic acid. Then, the temperature is gradually reduced, and the liquid is kept at a constant temperature to allow the dissolved glutamic acid to fully crystallize and precipitate, forming a secondary crystallization liquid. S3, Secondary purification centrifugation: The secondary crystallization liquid obtained in step S2 is subjected to secondary solid-liquid separation at a speed higher than that of the pretreatment centrifugation to obtain high-purity glutamic acid crystals; S4, Post-processing: Wash the high-purity glutamic acid crystals obtained from the second centrifugation to obtain the final glutamic acid.

2. The glutamic acid purification process by stepwise centrifugation and isoelectric crystallization according to claim 1, characterized in that, In step S1, the glutamic acid concentration in the glutamic acid crystallization fermentation broth is 80-120 g / L. Temperature is controlled using a plate heat exchanger with a temperature control accuracy of ±0.5℃. Solid-liquid separation is performed using a horizontal spiral sedimentation centrifuge or a disc centrifuge at a speed of 3000-5000 r / min for 15-30 min. During centrifugation, the feed rate is controlled at 10-20 m / s. 3 / h.

3. The glutamic acid purification process by stepwise centrifugation and isoelectric crystallization according to claim 2, characterized in that, The selection of centrifuge equipment in step S1 is based on the production line capacity: when the daily production capacity of the production line is ≤50 tons, a disc centrifuge is selected; when the daily production capacity of the production line is >50 tons, a horizontal spiral sedimentation centrifuge is selected; the differential speed control of the centrifuge equipment is 20-50 r / min.

4. The glutamic acid purification process by stepwise centrifugation and isoelectric crystallization according to claim 1, characterized in that, The isoelectric point of glutamic acid mentioned in step S2 is pH 3.2-3.

4. The pH is adjusted using concentrated sulfuric acid at a rate of 0.4 / h. The stirring speed during the pH adjustment process is 30 r / min. The gradient cooling process is as follows: first, the temperature of the clear liquid is reduced from 20-30℃ to 15-20℃ at a rate of 3℃ / h and kept at this temperature for 2-3 h, then reduced to 8-12℃ at a rate of 3℃ / h and kept at this temperature for 4-6 h. The total settling time is 6-9 h.

5. The glutamic acid purification process by stepwise centrifugation and isoelectric crystallization according to claim 1, characterized in that, The secondary centrifuge equipment mentioned in step S3 is of the same type as the pretreatment centrifuge equipment, with a centrifugation speed of 4000-6000 r / min, a centrifugation time of 20-40 min, and a feed rate of 8-15 m. 3 / h.

6. The glutamic acid purification process by stepwise centrifugation and isoelectric crystallization according to claim 5, characterized in that, In step S4, deionized water is used for washing for 15-20 minutes, and the amount of washing solution is 1.5-2.0 times the mass of the crystals.

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