Production process of N, N-bis (carboxymethyl)-L-glutamic acid tetrasodium salt

Abstract

The invention relates to the technical field of chemical synthesis, and particularly discloses a production process of N, N-bis (carboxymethyl)-L-glutamic acid tetrasodium salt. The method comprises the following steps: firstly, carrying out nanofiltration on N, N-bis (cyanomethyl)-L-sodium glutamate reaction liquid through a nanofiltration membrane with a specific pore diameter, and then continuously introducing the nanofiltration liquid into a reactor containing caustic soda liquid to carry out step-by-step alkaline hydrolysis reaction, so that the N, N-bis (cyanomethyl)-L-sodium glutamate is converted into N, N-bis (carboxymethyl)-L-glutamic acid tetrasodium salt at a maximum rate in an alkaline environment; meanwhile, according to the method, gradient heat preservation is carried out on the alkaline hydrolysis liquid through a multi-stage series heat preservation device, so that unreacted raw materials or by-products in the alkaline hydrolysis liquid are fully converted into N, N-bis (carboxymethyl)-L-glutamic acid tetrasodium salt; and carrying out multi-stage gradient heat preservation on the reaction liquid after the alkaline hydrolysis reaction, and separating, concentrating and adsorbing the heat preservation liquid after the gradient heat preservation to obtain a high-purity, high-concentration and low-viscosity N, N-bis (carboxymethyl)-L-glutamic acid tetrasodium water solution.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to a production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate. Background Art

[0002] Tetrasodium N,N-bis(carboxymethyl)-L-glutamate is a new type of green chelating agent with unique properties and wide applications. It has the characteristics of biodegradability, strong chelating ability, high solubility and detergency, synergistic effect, non-irritation and wide applicability. These characteristics have enabled it to be widely used in many fields such as detergents and water treatment agents, and it has shown huge market potential.

[0003] At present, most of the N,N-bis(carboxymethyl)-L-glutamate tetrasodium products are 38wt% or 47wt% aqueous solutions produced with glutamic acid / sodium glutamate, formaldehyde, hydrogen cyanide (liquid or gas), and liquid alkali as raw materials. Since the N,N-bis(carboxymethyl)-L-glutamate tetrasodium aqueous solution product inevitably contains small molecule sodium salts such as sodium formate, sodium hydroxyacetate, sodium acetate, and sodium hydroxide, it will have a certain impact on the product quality of N,N-bis(carboxymethyl)-L-glutamate tetrasodium, and in order to reduce transportation costs, it is difficult to continue to increase the concentration of the N,N-bis(carboxymethyl)-L-glutamate tetrasodium aqueous solution, because the presence of too many small molecule sodium salts and other impurities leads to a higher viscosity of the solution, which seriously affects the production efficiency of the concentration process, and too high viscosity will bring inconvenience to downstream customers. Secondly, in the production process, due to the use of raw materials formaldehyde and hydrocyanic acid, and the by-product ammonia, the N,N-bis(carboxymethyl)-L-glutamate tetrasodium product will inevitably carry NTA-3Na byproducts. If the concentration of NTA-3Na in the N,N-bis(carboxymethyl)-L-glutamate tetrasodium aqueous solution product is controlled within 0.1wt% according to customer requirements, it also brings great challenges to production personnel. In addition, this product has a large number of export businesses, and the high transportation costs also indirectly increase the production cost of N,N-bis(carboxymethyl)-L-glutamate tetrasodium products.

[0004] It is reported in the literature that in order to reduce the viscosity of glutamic acid N, N-diacetic acid sodium salt and increase its mass concentration, a method of adding a certain amount of glutamic acid-N, N-diacetic acid potassium salt thereto is adopted. Although this operation can increase the concentration of glutamic acid N, N-diacetic acid sodium salt to more than 60wt%, its purity cannot be guaranteed. Therefore, it is urgent to develop a high-concentration, low-viscosity N, N-bis (carboxymethyl) -L-glutamate tetrasodium production process to improve the product quality of N, N-bis (carboxymethyl) -L-glutamate tetrasodium, reduce the production cost of N, N-bis (carboxymethyl) -L-glutamate tetrasodium, and increase the market competitiveness of the product. Summary of the invention

[0005] In view of the problems of high viscosity, low concentration and high production cost in the existing industrial production process of N,N-bis(carboxymethyl)-L-glutamate tetrasodium aqueous solution products, the present invention provides a production process of N,N-bis(carboxymethyl)-L-glutamate tetrasodium. The process mainly comprises the following steps: after the N,N-bis(cyanomethyl)-L-glutamate sodium reaction liquid is pre-treated by nanofiltration, it is continuously introduced into a reactor containing liquid alkali by multi-stage feeding to perform step-by-step alkaline hydrolysis reaction, and the reaction liquid after the alkaline hydrolysis reaction is subjected to multi-stage gradient insulation, separation, concentration and adsorption to obtain a high-purity, high-concentration and low-viscosity N,N-bis(carboxymethyl)-L-glutamate tetrasodium aqueous solution. The process has a high degree of continuity, strong stability and high industrial promotion value.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0007] A production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, the method comprising the following steps:

[0008] S1, filtering the N,N-bis(cyanomethyl)-L-glutamate sodium reaction solution through a nanofiltration membrane with a pore size of 0.5 nm to 1 nm to obtain a N,N-bis(cyanomethyl)-L-glutamate sodium pretreatment solution;

[0009] S2, a part of the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment solution and all the liquid alkali are respectively continuously introduced into a multi-stage series reactor, wherein, after the reaction of each reactor is completed, the alkaline hydrolysis solution obtained in the reactor and a part of the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment solution are simultaneously and continuously introduced into the next reactor for step-by-step alkaline hydrolysis reaction to obtain an alkaline hydrolysis reaction solution;

[0010] S3, continuously passing the alkaline hydrolysis reaction liquid and hydrogen peroxide into a multi-stage series insulator for gradient insulation to obtain an insulation liquid;

[0011] S4, subjecting the insulation liquid to electrodialysis separation, nanofiltration, concentration, and activated carbon adsorption to remove impurities, to obtain an aqueous solution product of N,N-bis(carboxymethyl)-L-glutamate tetrasodium; the pore size of the activated carbon is 1nm to 30nm, and the iodine adsorption value is ≥1400mg / g;

[0012] Wherein, the addition amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid of the primary reactor does not exceed 50% of the total amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid, the addition amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid of the secondary reactor does not exceed 30% of the total amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid, the addition amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid of the tertiary reactor to the Nth reactor decreases step by step, and the sum of the addition amounts of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid of each reactor is 100%;

[0013] The temperature of each reactor increases with the number of stages. The temperature of the first reactor does not exceed 40°C, the temperature of the second reactor does not exceed 50°C, and the temperature of the Nth reactor does not exceed 65°C.

[0014] The temperature of each level of the insulator increases with the increase of the level. The temperature of the first level insulator does not exceed 65°C, the temperature of the second level insulator does not exceed 75°C, and the temperature of the Nth level insulator does not exceed 105°C.

[0015] Compared with the prior art, the production process of N,N-bis(carboxymethyl)-L-glutamate tetrasodium provided by the present invention comprises the following steps: the reaction liquid of N,N-bis(cyanomethyl)-L-glutamate is filtered through a nanofiltration membrane with a specific pore size, and then continuously introduced into a reactor containing liquid alkali for step-by-step alkaline hydrolysis reaction; and the feeding amount of N,N-bis(cyanomethyl)-L-glutamate sodium in each alkaline hydrolysis reaction is controlled, so that N,N-bis(cyanomethyl)-L-glutamate sodium is converted into N,N-bis(carboxymethyl)-L-glutamate tetrasodium at the maximum rate in an alkaline environment; at the same time, the method further performs gradient heat preservation on the alkaline hydrolysis liquid through a multi-stage series heat preservation device. The method comprises the steps of: heating the alkaline hydrolysis solution to a temperature such that the unreacted sodium N,N-bis(cyanomethyl)-L-glutamate and disodium N,N-bis(acetamido)-L-glutamate in the alkaline hydrolysis solution are fully converted into tetrasodium N,N-bis(carboxymethyl)-L-glutamate; in addition, in order to ensure the purity of the tetrasodium N,N-bis(carboxymethyl)-L-glutamate aqueous solution product, the present invention further separates the sodium hydroxide and the small molecular organic sodium salt in the tetrasodium N,N-bis(carboxymethyl)-L-glutamate aqueous solution through electrodialysis and nanofiltration of the insulating liquid, and finally obtains a high-purity tetrasodium N,N-bis(carboxymethyl)-L-glutamate aqueous solution product through concentration and adsorption removal of impurities.

[0016] The production process of N,N-bis(carboxymethyl)-tetrasodium L-glutamate provided by the invention has strong process stability and high automation degree. The purity of the prepared N,N-bis(carboxymethyl)-tetrasodium L-glutamate aqueous solution product can reach more than 99.9%, the concentration of NTA-3Na can be controlled below 0.01%, and the product concentration is high, with the mass concentration reaching more than 55%. Meanwhile, the product viscosity is low (the dynamic viscosity at 20°C is less than 400 centipoise), and the transportation cost of N,N-bis(carboxymethyl)-tetrasodium L-glutamate can be greatly reduced without affecting the use of downstream customers, which is conducive to industrial-scale production and has extremely high promotion and application value.

[0017] It should be noted that the N,N-bis(cyanomethyl)-L-sodium glutamate reaction solution described in the present invention is a reaction solution of sodium glutamate, formaldehyde and hydrocyanic acid as raw materials, and the molar ratio of sodium glutamate, formaldehyde and hydrocyanic acid is 1.0:2.01:2.0 to obtain the N,N-bis(cyanomethyl)-L-sodium glutamate reaction solution. The mass fraction of sodium N,N-bis(cyanomethyl)-L-glutamate in the reaction solution is 32% to 33%. The raw materials for preparing sodium N,N-bis(cyanomethyl)-L-glutamate can be commercially available substances, or can be prepared by conventional methods in the art, and the present invention does not make special restrictions.

[0018] Furthermore, in S1, the model of the nanofiltration membrane is RNM-303.

[0019] By using a specific nanofiltration membrane and pre-treating the N,N-bis(cyanomethyl)-L-glutamate sodium reaction solution at the above-mentioned operating temperature and pressure, small molecular compounds such as formaldehyde and hydroxyacetonitrile carried in the N,N-bis(cyanomethyl)-L-glutamate sodium reaction solution can be separated to ensure the purity of the N,N-bis(cyanomethyl)-L-glutamate sodium reaction solution, thereby laying a foundation for the subsequent viscosity control of the N,N-bis(carboxymethyl)-L-glutamate tetrasodium aqueous solution product.

[0020] Furthermore, the number of stages of the multi-stage series reactors is 3 to 4.

[0021] Preferably, the number of stages of the multi-stage series reactor is 4.

[0022] Furthermore, the number of stages of the multi-stage series insulators is 5 to 6.

[0023] Preferably, the number of stages of the multi-stage series insulators is 5.

[0024] The preferred number of reactors and insulators can ensure that sodium N,N-bis(cyanomethyl)-L-glutamate is fully converted into tetrasodium N,N-bis(carboxymethyl)-L-glutamate while reducing the equipment investment cost, and further ensure the product quality and yield of tetrasodium N,N-bis(carboxymethyl)-L-glutamate.

[0025] Furthermore, the mass concentration of the liquid caustic soda is 30% to 50%.

[0026] Preferably, the mass concentration of the liquid caustic soda is 50%.

[0027] It should be noted that sodium N,N-bis(cyanomethyl)-L-glutamate belongs to the nitrile compound. In a high temperature alkaline environment, if the alkaline hydrolysis reaction cannot be carried out in time, there will be a polymerization reaction of two molecules of sodium N,N-bis(cyanomethyl)-L-glutamate. The preferred concentration of liquid alkali can ensure that sodium N,N-bis(cyanomethyl)-L-glutamate can be converted into tetrasodium N,N-bis(carboxymethyl)-L-glutamate in time. At the same time, the preferred concentration of liquid alkali can also reduce the amount of water introduced into the system, create conditions for the subsequent concentration process, effectively reduce the subsequent dehydration amount, and further reduce the evaporation energy consumption on the basis of reducing the amount of wastewater.

[0028] Furthermore, the temperature of two adjacent reactors in the multi-stage series reactor increases step by step by 5°C to 15°C.

[0029] Furthermore, the temperature of two connected stages of the multi-stage series heat preservation device increases step by step by 5°C to 15°C.

[0030] By controlling the temperatures of the reactors at each level and the insulators at each level to increase step by step within the above range, the rate and conversion rate of converting sodium N,N-bis(cyanomethyl)-L-glutamate into tetrasodium N,N-bis(carboxymethyl)-L-glutamate can be increased, while minimizing heat utilization and ensuring the product quality of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, thereby increasing the yield and production efficiency of tetrasodium N,N-bis(carboxymethyl)-L-glutamate.

[0031] Furthermore, when the number of stages of the multi-stage series reactor is three, the temperature of the first-stage reactor is 35°C to 40°C, the temperature of the second-stage reactor is 45°C to 50°C, and the temperature of the third-stage reactor is 58°C to 63°C; the pressure of each stage of the reactor is ≤0.003MPa, and the residence time of the material in each stage of the reactor is 1.6h to 2.0h;

[0032] When the number of stages of the multi-stage series reactor is four, the temperature of the first-stage reactor is 28℃~33℃, the temperature of the second-stage reactor is 38℃~43℃, the temperature of the third-stage reactor is 48℃~53℃, and the temperature of the fourth-stage reactor is 58℃~63℃; the pressure of each stage of the reactor is ≤0.003MPa, and the residence time of the material in each stage of the reactor is 1.2h~1.5h.

[0033] Furthermore, when the number of stages of the multi-stage series insulator is five, the temperature of the first-stage insulator is 60°C to 65°C, the temperature of the second-stage insulator is 70°C to 75°C, the temperature of the third-stage insulator is 80°C to 85°C, the temperature of the fourth-stage insulator is 90°C to 95°C, and the temperature of the fifth-stage insulator is 100°C to 105°C. The pressure of each stage of the insulator is 0.003MPa to 0.02MPa, and the residence time of the material in each stage of the insulator is 1.2h to 1.5h.

[0034] When the number of stages of the multi-stage series insulator is six, the temperature of the first-stage insulator is 60℃~65℃, the temperature of the second-stage insulator is 65℃~70℃, the temperature of the third-stage insulator is 75℃~80℃, the temperature of the fourth-stage insulator is 85℃~90℃, the temperature of the fifth-stage insulator is 95℃~100℃, and the temperature of the sixth-stage insulator is 100℃~105℃. The pressure of each stage of the insulator is 0.003MPa~0.02MPa, and the residence time of the material in each stage of the insulator is 1.0h~1.25h.

[0035] The incubator is set in a multi-stage series form, and the residence time, temperature and pressure of the alkaline hydrolysis solution in the multi-stage thermostat are controlled to promote the full conversion of N,N-bis(cyanomethyl)-L-glutamate sodium and N,N-bis(acetamido)-L-glutamate disodium into N,N-bis(carboxymethyl)-L-glutamate tetrasodium, thereby ensuring the maximum conversion rate of N,N-bis(cyanomethyl)-L-glutamate sodium into N,N-bis(carboxymethyl)-L-glutamate tetrasodium. At the same time, as the temperature of each level of gradient incubator is gradually increased, the ammonia generated in the reaction system can be discharged from the system in time, creating a guarantee condition for controlling the NTA-3Na concentration in the N,N-bis(carboxymethyl)-L-glutamate tetrasodium product, thereby controlling the NTA-3Na concentration of the N,N-bis(carboxymethyl)-L-glutamate tetrasodium product to within 0.01wt%.

[0036] As a specific embodiment of the present invention, the production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate specifically comprises the following steps:

[0037] Step a, continuously passing the N,N-bis(cyanomethyl)-sodium L-glutamate reaction solution into a nanofiltration membrane separation system for nanofiltration to obtain a pretreated solution of N,N-bis(cyanomethyl)-sodium L-glutamate;

[0038] Step b, continuously introducing the first part of the sodium N,N-bis(cyanomethyl)-L-glutamate pretreatment solution and all the liquid alkali into a primary reactor for alkaline hydrolysis reaction to obtain a primary reaction solution;

[0039] Step c, simultaneously and continuously introducing the primary reaction liquid and the second part of the sodium N,N-bis(cyanomethyl)-L-glutamate pretreatment liquid into a secondary reactor for alkaline hydrolysis reaction to obtain a secondary reaction liquid;

[0040] Step d, simultaneously and continuously introducing the secondary reaction liquid and the third part of the sodium N,N-bis(cyanomethyl)-L-glutamate pretreatment liquid into a tertiary reactor for alkaline hydrolysis reaction to obtain a tertiary reaction liquid;

[0041] Step e, simultaneously and continuously introducing the tertiary reaction liquid and the remaining sodium N,N-bis(cyanomethyl)-L-glutamate pretreatment liquid into a fourth-stage reactor for alkaline hydrolysis reaction to obtain a fourth-stage reaction liquid;

[0042] Step f, continuously passing the fourth-stage reaction liquid and hydrogen peroxide into a first-stage insulator for insulation to obtain a first-stage insulation liquid;

[0043] Step g, sequentially and continuously passing the first-level insulation liquid into the second-level insulation device to the fifth-level insulation device for insulation, to obtain a fifth-level insulation liquid;

[0044] Step h, continuously passing the five-stage insulation liquid into an electrodialysis separation system for separation to obtain an electrodialysis liquid;

[0045] Step i, continuously passing the electrodialysis liquid into a nanofiltration membrane separation system for nanofiltration to obtain a nanofiltrate;

[0046] Step j, continuously passing the nanofiltrate into a concentrator for concentration to obtain a concentrated solution;

[0047] Step k, continuously passing the concentrated solution into an adsorber to obtain a tetrasodium N,N-bis(carboxymethyl)-L-glutamate aqueous solution product.

[0048] The above-mentioned production method of tetrasodium N,N-bis(carboxymethyl)-L-glutamate is as follows: the pre-treated liquid of sodium N,N-bis(cyanomethyl)-L-glutamate separated and pre-treated by nanofiltration membrane is divided into four streams and continuously introduced into the reactor; wherein, after the first stream of raw material sodium N,N-bis(cyanomethyl)-L-glutamate and all the liquid alkali are continuously introduced into the primary reactor, sodium N,N-bis(cyanomethyl)-L-glutamate can be timely converted into tetrasodium N,N-bis(carboxymethyl)-L-glutamate under the condition of sufficient liquid alkali, wherein a certain amount of disodium N,N-bis(acetamido)-L-glutamate will be present; the first stream of raw material sodium N,N-bis(cyanomethyl)-L-glutamate and all the liquid alkali are continuously introduced into the primary reactor; The primary reaction liquid and the second raw material N,N-bis(cyanomethyl)-L-glutamate sodium are continuously introduced into the secondary reactor. Since the primary reaction liquid contains a certain concentration of sodium hydroxide, the secondary introduced N,N-bis(cyanomethyl)-L-glutamate sodium continues to be converted into N,N-bis(carboxymethyl)-L-glutamate tetrasodium and N,N-bis(acetamido)-L-glutamate disodium under alkaline conditions; at the same time, the residual N,N-bis(acetamido)-L-glutamate disodium in the primary reaction liquid will continue to be alkaline hydrolyzed in the secondary reactor to be converted into N,N-bis(carboxymethyl)-L-glutamate tetrasodium; the secondary reaction liquid derived from the secondary reactor The liquid and the third stream of raw material N,N-bis(cyanomethyl)-L-glutamate sodium are continuously introduced into the third-stage reactor. Since there is a certain concentration of sodium hydroxide in the secondary reaction liquid, the N,N-bis(cyanomethyl)-L-glutamate sodium added three times can continue to be converted into N,N-bis(acetamido)-L-glutamate disodium and N,N-bis(carboxymethyl)-L-glutamate tetrasodium under alkaline conditions; at the same time, the N,N-bis(acetamido)-L-glutamate disodium remaining in the first and second reactors continues to be alkaline hydrolyzed into N,N-bis(carboxymethyl)-L-glutamate tetrasodium in the third-stage reactor; the third stream of raw material N,N-bis(cyanomethyl)-L-glutamate sodium extracted from the third-stage reactor is further hydrolyzed into N,N-bis(carboxymethyl)-L-glutamate tetrasodium. The first-stage reaction liquid and the fourth stream of raw material N,N-bis(cyanomethyl)-L-sodium glutamate are continuously introduced into the fourth-stage reactor. Since there is still a certain concentration of sodium hydroxide in the third-stage reaction liquid, the N,N-bis(cyanomethyl)-L-sodium glutamate added four times can continue to be converted into N,N-bis(acetamido)-L-glutamate disodium and N,N-bis(carboxymethyl)-L-glutamate tetrasodium under alkaline conditions; at the same time, the N,N-bis(acetamido)-L-glutamate disodium remaining in the first-stage reactor, the second-stage reactor and the third-stage reactor continues to be alkaline-hydrolyzed into N,N-bis(carboxymethyl)-L-glutamate tetrasodium in the fourth-stage reactor. However, the fourth-stage reaction liquid derived from the fourth-stage reactor still contains a certain concentration of N,N-bis(acetamido)-L-glutamate disodium. Therefore, a five-stage gradient insulator is added in step f and step g to fully convert the residual N,N-bis(acetamido)-L-glutamate disodium and unreacted N,N-bis(cyanomethyl)-L-glutamate sodium in the fourth-stage reaction liquid into N,N-bis(carboxymethyl)-L-glutamate tetrasodium.In addition, the small-molecule sodium salts such as sodium hydroxide, sodium formate, sodium acetate, and sodium hydroxyacetate carried in the insulation liquid are subsequently fully removed through the electrodialysis separation system and the nanofiltration membrane separation system, which not only ensures the purity of the N,N-bis(carboxymethyl)-L-glutamate tetrasodium product, but also controls the pH value of the N,N-bis(carboxymethyl)-L-glutamate tetrasodium product, creating guarantee conditions for effectively controlling the viscosity of N,N-bis(carboxymethyl)-L-glutamate tetrasodium. Further, in order to effectively increase the concentration of the N,N-bis(carboxymethyl)-L-glutamate tetrasodium aqueous solution, the nanofiltrate is concentrated and dehydrated by a concentrator, and then adsorbed by an activated carbon adsorber to remove the colored substances carried therein, and a high-concentration, low-viscosity N,N-bis(carboxymethyl)-L-glutamate tetrasodium product aqueous solution is obtained.

[0049] Furthermore, in step a, the operating temperature of the nanofiltration membrane separation system is 10°C to 20°C, and the working pressure is 25 bar to 30 bar.

[0050] Furthermore, the first part of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution is 45% to 50% of the total amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution, the second part of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution is 25% to 30% of the total amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution, and the third part of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution is 15% to 20% of the total amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution.

[0051] Feeding the materials of the multi-stage series reactor according to the above ratio can timely convert sodium N,N-bis(cyanomethyl)-L-glutamate into tetrasodium N,N-bis(carboxymethyl)-L-glutamate, thereby reducing the probability of polymerization between sodium N,N-bis(cyanomethyl)-L-glutamate molecules, thereby further ensuring the purity and yield of tetrasodium N,N-bis(carboxymethyl)-L-glutamate products.

[0052] Furthermore, in step b, the liquid alkali is calculated as NaOH, the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid is calculated as N,N-bis(cyanomethyl)-L-sodium glutamate, and the molar ratio of the liquid alkali to the total amount of N,N-bis(cyanomethyl)-L-sodium glutamate is 3.04:1 to 3.07:1.

[0053] Furthermore, in step f, the mass concentration of the hydrogen peroxide is 10% to 15%, and H 2 O 2 The mass ratio to NaOH in liquid alkali is 1:360~1:400.

[0054] In an alkaline environment, the generation of organic impurities is inevitable in the process of converting sodium N,N-bis(cyanomethyl)-L-glutamate into tetrasodium N,N-bis(carboxymethyl)-L-glutamate and disodium N,N-bis(acetamido)-L-glutamate. When the fourth-level alkaline hydrolyzate is passed into the first-level insulator, a hydrogen peroxide solution is passed, and the temperature of the first-level insulator and the addition ratio of hydrogen peroxide are controlled. Under the condition that disodium N,N-bis(acetamido)-L-glutamate and tetrasodium N,N-bis(carboxymethyl)-L-glutamate are not decomposed, colored organic impurities are effectively removed, and the product purity of tetrasodium N,N-bis(carboxymethyl)-L-glutamate is further guaranteed.

[0055] In traditional operation, hydrogen peroxide is added after the step of atmospheric pressure concentration and dehydration. The inventor has found that adding hydrogen peroxide in this step has a poor decolorization effect and will cause the decomposition of the N, N-bis (carboxymethyl) -L-glutamate tetrasodium product. In addition, if the amount of hydrogen peroxide added is inaccurate or there is too much residual hydrogen peroxide in the material, when activated carbon is added, the decomposition of hydrogen peroxide will cause the problem of material impact, which has serious safety hazards. The present invention chooses to add hydrogen peroxide during the first-level insulation. Under the premise of ensuring the decolorization effect, there is enough time before adding activated carbon to allow hydrogen peroxide to decompose under alkaline high temperature conditions, providing protection for safe production.

[0056] Furthermore, in step h, the electrodialysis separation system is an EX-3BT electrodialysis separation system, whose operating temperature is 30°C to 40°C, the working pressure is 0.01MPa to 0.02MPa, the flow rate of the five-stage insulation liquid entering the electrodialysis separation system is 4kg / h to 8kg / h, and the discharge pH of the electrodialysis separation system is controlled to be 9.90 to 10.10.

[0057] The preferred electrodialysis system uses an anion exchange membrane and a cation exchange membrane. Without introducing external ions, the excess sodium hydroxide in the insulation liquid can be discharged from the system by controlling the flow rate of the insulation liquid in the electrodialysis separation system. The separation end point of the electrodialysis separation system is determined by controlling the pH of the discharge liquid. When the pH value of the discharge liquid reaches 9.90 to 10.10, it is the separation end point. Electrodialysis separation is beneficial to reduce the viscosity of the N,N-bis(carboxymethyl)-L-glutamate tetrasodium aqueous solution product.

[0058] Furthermore, in step i, the operating temperature of the nanofiltration membrane separation system is 25°C to 30°C, the working pressure is 25 bar to 30 bar, and the flow rate of the electrodialysis liquid entering the nanofiltration membrane separation system is 4 kg / h to 8 kg / h.

[0059] Furthermore, in step i, the model of the nanofiltration membrane separation system is RNM-1812G.

[0060] According to the above-mentioned temperature and pressure control nanofiltration membrane separation system, the electrodialysis liquid is subjected to nanofiltration membrane separation, which can effectively separate small molecular organic acid sodium salts such as sodium formate, sodium acetate, sodium hydroxyacetate, etc. in the electrodialysis liquid, greatly improving the liquid phase purity of the aqueous solution of N,N-bis(carboxymethyl)-L-glutamate tetrasodium product to more than 99.9%, further laying the foundation for controlling the viscosity of N,N-bis(carboxymethyl)-L-glutamate tetrasodium product.

[0061] Furthermore, in step j, the operating temperature of the concentrator is 40° C. to 50° C., and the pressure is -0.095 MPa to -0.1 MPa.

[0062] The concentration of tetrasodium N,N-bis(carboxymethyl)-L-glutamate in the nanofiltrate derived from the nanofiltration membrane separation system is 35wt% to 45wt%. In order to save transportation costs, the nanofiltrate is concentrated under the above-defined conditions. The above-mentioned concentration conditions can not only improve the dehydration efficiency, but also avoid the problem of decomposition and deterioration of tetrasodium N,N-bis(carboxymethyl)-L-glutamate at high temperature for a long time. At the same time, since tetrasodium N,N-bis(carboxymethyl)-L-glutamate has a strong chelating ability, the above-mentioned temperature control can reduce its corrosion rate to stainless steel equipment.

[0063] Exemplarily, the concentrator is an MVR evaporation system, and a conventional simple evaporation system in the art may also be used, which is not particularly limited in the present invention.

[0064] Furthermore, in step k, the filling volume of the activated carbon in the adsorber is 90% to 95% of the volume of the adsorber, and the operating temperature of the adsorber is 60° C. to 70° C.

[0065] Preferably, the model of activated carbon is SWJS-101.

[0066] Controlling the filling volume of activated carbon in the adsorber can effectively improve the utilization rate of the adsorber. At the same time, the adsorber will also have a certain expansion phenomenon during continuous operation. The above filling volume ensures the expansion space of the activated carbon.

[0067] Under high temperature and alkaline conditions, during the conversion of sodium N,N-bis(cyanomethyl)-L-glutamate into tetrasodium N,N-bis(carboxymethyl)-L-glutamate, there is inevitably a polymerization reaction between two molecules of sodium N,N-bis(cyanomethyl)-L-glutamate, including the polymerization reaction of other small molecular nitrile compounds. The use of activated carbon of specified models and specifications to adsorb the intermediate material of tetrasodium N,N-bis(carboxymethyl)-L-glutamate can effectively remove the colored impurities generated by the polymerization of nitrile compounds in the material; at the same time, controlling the operating temperature of the adsorber within the above range can ensure the adsorption effect of the activated carbon under the premise of minimum energy consumption, and further ensure the product quality of tetrasodium N,N-bis(carboxymethyl)-L-glutamate.

[0068] Furthermore, the primary reactor is provided with a feed port for liquid alkali and sodium N,N-bis(cyanomethyl)-L-glutamate, the secondary reactor is provided with a feed port for primary reaction liquid and sodium N,N-bis(cyanomethyl)-L-glutamate, the tertiary reactor is provided with a feed port for secondary reaction liquid and sodium N,N-bis(cyanomethyl)-L-glutamate; the quaternary reactor is provided with a feed port for tertiary reaction liquid and sodium N,N-bis(cyanomethyl)-L-glutamate; and the primary reactor, the secondary reactor, the tertiary reactor and the quaternary reactor are all provided with a liquid discharge port for continuously draining the reaction liquid generated in the corresponding reactor.

[0069] Furthermore, the first-stage insulator is provided with a feeding port for the fourth-stage reaction liquid and hydrogen peroxide.

[0070] Furthermore, each of the first to fifth stage insulators is provided with a steam exhaust port for timely exhausting ammonia generated by the reaction liquid during the insulation process.

[0071] Ammonia entrained in the fourth-stage alkaline hydrolysis liquid and residual N,N-bis(acetamido)-L-glutamate disodium will generate a certain amount of ammonia in the process of converting into N,N-bis(carboxymethyl)-L-glutamate tetrasodium. By arranging steam exhaust ports on the second-stage, third-stage, fourth-stage and fifth-stage gradient insulators, the ammonia contained in the reaction system can be promptly discharged from the reaction system through water vapor through the steam exhaust ports, so as to avoid the presence of ammonia and untimely discharge, resulting in the reaction of ammonia with formaldehyde in the intermediate material of N,N-bis(carboxymethyl)-L-glutamate tetrasodium to generate urotropine impurities, and ammonia will also react with sodium hydroxyacetate to generate NTA-3Na impurities, so that the purity of N,N-bis(carboxymethyl)-L-glutamate tetrasodium product cannot be guaranteed.

[0072] The production process of N,N-bis(carboxymethyl)-L-glutamate tetrasodium provided by the invention has strong process stability, the purity of the prepared N,N-bis(carboxymethyl)-L-glutamate tetrasodium product reaches more than 99.9%, the content of NTA-3Na is controlled within 0.01wt%, and the concentration of the N,N-bis(carboxymethyl)-L-glutamate tetrasodium aqueous solution product is increased from the traditional 47wt% to more than 55.5wt%, and the viscosity at 20°C can be controlled within 400 centipoise. When the concentration is increased, the viscosity of the material will not affect the use of downstream customers due to excessive increase, and the transportation cost of the product is greatly reduced; meanwhile, the process route has a high degree of automation, greatly reduces the labor intensity of operators, and the occurrence of unstable product quality problems caused by factors such as the skill level of operators, is suitable for large-scale production and application, and has high industrial promotion value. DETAILED DESCRIPTION

[0073] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0074] In order to better illustrate the present invention, further examples are given below.

[0075] The sodium hydroxide and N,N-bis(cyanomethyl)-L-glutamate sodium reaction solution used in the following examples and comparative examples are produced by Hebei Chengxin Group Co., Ltd., wherein the N,N-bis(cyanomethyl)-L-glutamate sodium reaction solution is an aqueous solution obtained by reacting sodium glutamate, formaldehyde and hydrogen cyanide as raw materials in a molar ratio of sodium glutamate: formaldehyde: hydrogen cyanide = 1.0:2.01:2.0, and the mass concentration of the N,N-bis(cyanomethyl)-L-glutamate sodium reaction solution is 32.8wt%, the residual formaldehyde concentration is 0.085wt%, and the hydroxyacetonitrile concentration is 0.25wt%.

[0076] The manufacturers of SWJS-101 and SWJS-103 activated carbons are both Shaowu Jinshou Activated Carbon Co., Ltd.; hydrogen peroxide is a 27.0 wt % aqueous solution provided by Hebei Tianyuan Chemical Group Co., Ltd. (soft water is added in proportion for dilution).

[0077] The manufacturers of RNM301 nanofiltration membrane separation system, RNM-303 nanofiltration membrane separation system, RNM-1811G and RNM-1812G nanofiltration membrane separation systems are all Hangzhou Reina Membrane Engineering Co., Ltd.; the manufacturer of EX-3BT electrodialysis separation system is Quzhou Lanran New Materials Co., Ltd.

[0078] The manufacturer of 4A molecular sieve is Shanghai Xinao Molecular Sieve Co., Ltd.

[0079] Example 1

[0080] This embodiment provides a production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, comprising the following steps:

[0081] Step 1, controlling the operating temperature of the RNM-303 nanofiltration membrane separation system to 10°C and the working pressure to 25.0 bar, continuously introducing the N,N-bis(cyanomethyl)-L-sodium glutamate reaction solution with a concentration of 32.8wt% into the RNM-303 nanofiltration membrane separation system at a rate of 4.15kg / h, obtaining 4.1kg / h of N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution, detecting the formaldehyde concentration therein to be 0.002wt%, and the hydroxyacetonitrile concentration therein to be 0.002wt%;

[0082] Step 2, controlling the temperature of the primary reactor to 28° C. and the pressure to 0.001 MPa, and continuously introducing the above-mentioned N, N-bis(cyanomethyl)-L-glutamate sodium pretreatment liquid at a rate of 1.968 kg / h and a 50% sodium hydroxide solution at a mass concentration of 1.234 kg / h into the primary reactor for alkaline hydrolysis, and controlling the residence time of the material in the primary reactor to be 1.2 h;

[0083] Step 3, controlling the temperature of the secondary reactor to 38 ° C and the pressure to 0.001 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment solution into the secondary reactor at a feed rate of 1.23 kg / h, and continuously introducing the primary reaction solution extracted from the primary reactor into the secondary reactor at a feed rate of 3.2 kg / h, and controlling the residence time of the material in the secondary reactor to 1.2h;

[0084] Step 4, controlling the temperature of the tertiary reactor to 48 ° C and the pressure to 0.001 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the tertiary reactor at a feed rate of 0.615 kg / h, and continuously introducing the secondary reaction liquid extracted from the secondary reactor into the tertiary reactor at a feed rate of 4.428 kg / h, and controlling the residence time of the material in the tertiary reactor to 1.2 h;

[0085] Step 5, controlling the temperature of the fourth-stage reactor to 58 ° C and the pressure to 0.001 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the fourth-stage reactor at a feed rate of 0.287 kg / h, and continuously introducing the third-stage reaction liquid extracted from the third-stage reactor into the fourth-stage reactor at a feed rate of 5.04 kg / h, and controlling the residence time of the material in the fourth-stage reactor to be 1.2h;

[0086] Step 6: Control the temperature of the first-stage insulator to 60° C. and the pressure to 0.003 MPa, and continuously introduce the fourth-stage reaction liquid extracted from the fourth-stage reactor into the first-stage insulator at a feed rate of 5.325 kg / h for insulation. At the same time, continuously introduce 10 wt% hydrogen peroxide into the first-stage insulator at a feed rate of 0.0167 kg / h, and control the residence time of the material in the first-stage insulator to be 1.2 h;

[0087] Step 7: Control the temperature of the secondary insulator to 70°C and the pressure to 0.003MPa, continuously introduce the insulation liquid from the primary insulator into the secondary insulator at a feed rate of 5.341kg / h for insulation, control the residence time of the material in the secondary insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the secondary insulator to be 0.056kg / h;

[0088] Step 8: Control the temperature of the third-stage insulator to 80°C and the pressure to 0.01MPa, continuously introduce the insulation liquid from the second-stage insulator into the third-stage insulator at a feed rate of 5.284kg / h for insulation, control the residence time of the material in the third-stage insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the third-stage insulator to be 0.074kg / h;

[0089] Step nine, control the temperature of the fourth-stage insulator to 90°C and the pressure to 0.01MPa, continuously introduce the insulation liquid from the third-stage insulator into the fourth-stage insulator at a feed rate of 5.21kg / h for insulation, control the residence time of the material in the fourth-stage insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the fourth-stage insulator to be 0.185kg / h;

[0090] Step 10, control the temperature of the five-stage insulator to 100°C and the pressure to 0.02MPa, continuously introduce the insulation liquid from the four-stage insulator into the five-stage insulator at a feed rate of 5.023kg / h for insulation, control the residence time of the material in the five-stage insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the five-stage insulator to be 0.71kg / h;

[0091] Step 11, continuously collect 43.1kg of insulation liquid produced from the five-stage insulator for 10 hours, sample and test the sodium hydroxide content in the insulation liquid to 0.210%. Control the operating temperature of the EX-3BT electrodialysis separation system to 30°C and the operating pressure to 0.01MPa, and continuously introduce the insulation liquid produced from the five-stage insulator into the EX-3BT electrodialysis separation system at a feed rate of 4kg / h, control the pH value of the material outlet of the EX-3BT electrodialysis separation system to 9.90, and produce 42.95kg of liquid;

[0092] Step 12, controlling the operating temperature of the RNM-1812G nanofiltration membrane separation system to 25°C and the operating pressure to 25.0 bar, continuously introducing the material extracted from the EX-3BT electrodialysis separation system into the RNM-1812G nanofiltration membrane separation system at a feed rate of 4 kg / h, and obtaining 42.02 kg of nanofiltrate from the extraction port of the RNM-1812G nanofiltration membrane separation system, and sampling and detecting the content of tetrasodium N,N-bis(carboxymethyl)-L-glutamate to be 41.45%;

[0093] Step 13, controlling the temperature of the concentrator to 40°C and the pressure to -0.1 MPa, vacuum concentrating the nanofiltrate to obtain 31.27 kg of concentrated liquid, and collecting 10.46 kg of concentrated water;

[0094] Step 14, filling SWJS-101 activated carbon in the adsorber, the filling volume is 90% of the volume of the adsorber, controlling the operating temperature of the adsorber to 60 ° C, and continuously introducing the concentrate into the adsorber at a feed rate of 5 kg / h for adsorption and decolorization to obtain 30.85 kg of N, N-bis (carboxymethyl) -L-glutamate tetrasodium aqueous solution product, sampling and testing N, N-bis (carboxymethyl) -L-glutamate tetrasodium content of 55.52%, liquid phase purity 99.93%, NTA-3Na content 0.0021wt%, platinum cobalt chromaticity 45, 20 ° C dynamic viscosity of 380 centipoise, accounting N, N-bis (carboxymethyl) -L-glutamate tetrasodium pure yield is 94.944%.

[0095] Example 2

[0096] This embodiment provides a production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, comprising the following steps:

[0097] Step 1, controlling the operating temperature of the RNM-303 nanofiltration membrane separation system to 20°C and the working pressure to 30.0 bar, continuously introducing a 32.8wt% N,N-bis(cyanomethyl)-L-sodium glutamate reaction solution into the RNM-303 nanofiltration membrane separation system at a rate of 4.17kg / h to obtain 4.11kg / h of N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution, wherein the formaldehyde concentration is detected to be 0.0022wt%, and the concentration of hydroxyacetonitrile is 0.0025wt%;

[0098] Step 2, controlling the temperature of the primary reactor to 33° C. and the pressure to 0.003 MPa, and continuously introducing the above-mentioned N, N-bis(cyanomethyl)-L-glutamate sodium pretreatment liquid at a rate of 1.973 kg / h and a 50% sodium hydroxide solution at a mass concentration of 1.249 kg / h into the primary reactor for alkaline hydrolysis, and controlling the residence time of the material in the primary reactor to 1.5 h;

[0099] Step 3, controlling the temperature of the secondary reactor to 43 ° C and the pressure to 0.003 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment solution into the secondary reactor at a feed rate of 1.233 kg / h, and continuously introducing the primary reaction solution extracted from the primary reactor into the secondary reactor at a feed rate of 3.22 kg / h, and controlling the residence time of the material in the secondary reactor to 1.5h;

[0100] Step 4, controlling the temperature of the tertiary reactor to 53 ° C and the pressure to 0.003 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the tertiary reactor at a feed rate of 0.617 kg / h, and continuously introducing the secondary reaction liquid extracted from the secondary reactor into the tertiary reactor at a feed rate of 4.45 kg / h, and controlling the residence time of the material in the tertiary reactor to 1.5h;

[0101] Step 5, controlling the temperature of the fourth-stage reactor to 63 ° C and the pressure to 0.003 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the fourth-stage reactor at a feed rate of 0.288 kg / h, and continuously introducing the third-stage reaction liquid extracted from the third-stage reactor into the fourth-stage reactor at a feed rate of 5.06 kg / h, and controlling the residence time of the material in the fourth-stage reactor to be 1.5h;

[0102] Step 6, controlling the temperature of the first-stage insulator to 65°C and the pressure to 0.003MPa, continuously introducing the fourth-stage reaction liquid extracted from the fourth-stage reactor into the first-stage insulator at a feed rate of 5.34kg / h for insulation, and at the same time, continuously introducing 15wt% hydrogen peroxide into the first-stage insulator at a feed rate of 0.0104kg / h, and controlling the residence time of the material in the first-stage insulator to be 1.5h;

[0103] Step 7: Control the temperature of the secondary insulator to 75°C and the pressure to 0.003MPa, continuously introduce the insulation liquid from the primary insulator into the secondary insulator at a feed rate of 5.323kg / h for insulation, control the residence time of the material in the secondary insulator to 1.5h, and monitor the exhaust rate collected at the steam outlet of the secondary insulator to be 0.059kg / h;

[0104] Step 8, control the temperature of the third-stage insulator to 85°C and the pressure to 0.02MPa, continuously introduce the insulation liquid from the second-stage insulator into the third-stage insulator at a feed rate of 5.243kg / h for insulation, control the residence time of the material in the third-stage insulator to 1.5h, and monitor the exhaust rate collected at the steam outlet of the third-stage insulator to be 0.078kg / h;

[0105] Step nine, control the temperature of the fourth-stage insulator to 95°C and the pressure to 0.02MPa, continuously introduce the insulation liquid from the third-stage insulator into the fourth-stage insulator at a feed rate of 5.155kg / h for insulation, control the residence time of the material in the fourth-stage insulator to 1.5h, and monitor the exhaust rate collected at the steam outlet of the fourth-stage insulator to be 0.218kg / h;

[0106] Step 10, control the temperature of the five-stage insulator to 105°C and the pressure to 0.02MPa, continuously introduce the insulation liquid from the four-stage insulator into the five-stage insulator at a feed rate of 4.925kg / h for insulation, control the residence time of the material in the five-stage insulator to 1.5h, and monitor the exhaust rate collected at the steam outlet of the five-stage insulator to be 0.78kg / h;

[0107] Step 11, continuously collect 41.33kg of insulation liquid produced from the five-stage insulator for 10 hours, sample and test the sodium hydroxide content in the insulation liquid to 0.338%. Control the operating temperature of the EX-3BT electrodialysis separation system to 40°C and the operating pressure to 0.02MPa, and continuously introduce the insulation liquid produced from the five-stage insulator into the EX-3BT electrodialysis separation system at a feed rate of 4kg / h, control the pH value of the material production outlet of the EX-3BT electrodialysis separation system to 10.10, and produce 41.06kg of liquid;

[0108] Step 12, controlling the operating temperature of the RNM-1812G nanofiltration membrane separation system to 30°C and the operating pressure to 30.0 bar, continuously introducing the material extracted from the EX-3BT electrodialysis separation system into the RNM-1812G nanofiltration membrane separation system at a feed rate of 4 kg / h, and obtaining 40.35 kg of nanofiltrate from the extraction port of the RNM-1812G nanofiltration membrane separation system, and sampling and detecting the content of tetrasodium N,N-bis(carboxymethyl)-L-glutamate to be 43.41%;

[0109] Step 13, controlling the temperature of the concentrator to 50°C and the pressure to -0.095MPa, vacuum concentrating the nanofiltrate to obtain 31.45kg of concentrated liquid, and collecting 8.68kg of concentrated water;

[0110] Step 14, filling SWJS-101 activated carbon in the adsorber, the filling volume is 95% of the volume of the adsorber, controlling the operating temperature of the adsorber to 70 ° C, and continuously introducing the concentrate into the adsorber at a feed rate of 5 kg / h for adsorption and decolorization to obtain 31.13 kg of N, N-bis (carboxymethyl) -L-glutamate tetrasodium aqueous solution product, sampling and testing N, N-bis (carboxymethyl) -L-glutamate tetrasodium content of 55.55%, liquid phase purity of 99.95%, NTA-3Na content of 0.0026wt%, platinum cobalt chromaticity of 42, 20 ° C dynamic viscosity of 385 centipoise, accounting N, N-bis (carboxymethyl) -L-glutamate tetrasodium pure yield is 95.417%.

[0111] Example 3

[0112] This embodiment provides a production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, comprising the following steps:

[0113] Step 1, controlling the operating temperature of the RNM-303 nanofiltration membrane separation system to 15°C and the working pressure to 27.0 bar, continuously introducing the N,N-bis(cyanomethyl)-L-sodium glutamate reaction solution with a concentration of 32.8wt% into the RNM-303 nanofiltration membrane separation system at a rate of 4.18kg / h, obtaining 4.12kg / h of N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution, detecting the formaldehyde concentration therein to be 0.0019wt%, and the concentration of hydroxyacetonitrile to be 0.0023wt%;

[0114] Step 2, controlling the temperature of the primary reactor to 30° C. and the pressure to 0.002 MPa, introducing the above-mentioned N, N-bis(cyanomethyl)-L-glutamate sodium pretreatment liquid at a rate of 1.978 kg / h and a 32% sodium hydroxide solution at a rate of 1.946 kg / h into the primary reactor for alkaline hydrolysis, and controlling the residence time of the material in the primary reactor to be 1.4 h;

[0115] Step 3, controlling the temperature of the secondary reactor to 40 ° C and the pressure to 0.002 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment solution into the secondary reactor at a feed rate of 1.236 kg / h, and continuously introducing the primary reaction solution extracted from the primary reactor into the secondary reactor at a feed rate of 3.903 kg / h, and controlling the residence time of the material in the secondary reactor to 1.4h;

[0116] Step 4, controlling the temperature of the tertiary reactor to 50 ° C and the pressure to 0.002 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the tertiary reactor at a feed rate of 0.618 kg / h, and continuously introducing the secondary reaction liquid extracted from the secondary reactor into the tertiary reactor at a feed rate of 5.12 kg / h, and controlling the residence time of the material in the tertiary reactor to 1.4h;

[0117] Step 5, controlling the temperature of the fourth-stage reactor to 60° C. and the pressure to 0.002 MPa, continuously introducing the N,N-bis(cyanomethyl)-L-glutamate sodium pretreatment solution into the fourth-stage reactor at a feed rate of 0.288 kg / h, and continuously introducing the third-stage reaction solution extracted from the third-stage reactor into the fourth-stage reactor at a feed rate of 5.72 kg / h, and controlling the residence time of the material in the fourth-stage reactor to be 1.4 h;

[0118] Step 6, controlling the temperature of the first-stage insulator to 63°C and the pressure to 0.002MPa, continuously introducing the fourth-stage reaction liquid extracted from the fourth-stage reactor into the first-stage insulator at a feed rate of 5.988kg / h for insulation, and at the same time, continuously introducing 13wt% hydrogen peroxide into the first-stage insulator at a feed rate of 0.0124kg / h, and controlling the residence time of the material in the first-stage insulator to be 1.4h;

[0119] Step 7: Control the temperature of the secondary insulator to 73°C and the pressure to 0.002MPa, continuously introduce the insulation liquid from the primary insulator into the secondary insulator at a feed rate of 5.985kg / h for insulation, control the residence time of the material in the secondary insulator to 1.4h, and monitor the exhaust rate collected at the steam outlet of the secondary insulator to be 0.058kg / h;

[0120] Step 8, control the temperature of the third-stage insulator to 83°C and the pressure to 0.015MPa, continuously introduce the insulation liquid from the second-stage insulator into the third-stage insulator at a feed rate of 5.907kg / h for insulation, control the residence time of the material in the third-stage insulator to 1.4h, and monitor the exhaust rate collected at the steam outlet of the third-stage insulator to be 0.0763kg / h;

[0121] Step nine, control the temperature of the fourth-stage insulator to 93°C and the pressure to 0.015MPa, continuously introduce the insulation liquid from the third-stage insulator into the fourth-stage insulator at a feed rate of 5.825kg / h for insulation, control the residence time of the material in the fourth-stage insulator to 1.4h, and monitor the exhaust rate collected at the steam outlet of the fourth-stage insulator to be 0.205kg / h;

[0122] Step 10, control the temperature of the five-stage insulator to 103°C and the pressure to 0.015MPa, continuously introduce the insulation liquid from the four-stage insulator into the five-stage insulator at a feed rate of 5.605kg / h for insulation, control the residence time of the material in the five-stage insulator to 1.4h, and monitor the exhaust rate collected at the steam outlet of the five-stage insulator to be 0.747kg / h;

[0123] Step 11, continuously collect 48.49 kg of insulation liquid produced from the five-stage insulator for 10 hours, sample and test the sodium hydroxide content in the insulation liquid to 0.252%. Control the operating temperature of the EX-3BT electrodialysis separation system to 35°C and the operating pressure to 0.015 MPa, and continuously introduce the insulation liquid produced from the five-stage insulator into the EX-3BT electrodialysis separation system at a feed rate of 4 kg / h, control the pH value of the material production outlet of the EX-3BT electrodialysis separation system to 10.00, and produce 48.17 kg of liquid;

[0124] Step 12, controlling the operating temperature of the RNM-1812G nanofiltration membrane separation system to 27°C and the operating pressure to 27.0 bar, continuously introducing the material extracted from the EX-3BT electrodialysis separation system into the RNM-1812G nanofiltration membrane separation system at a feed rate of 4 kg / h, and obtaining 47.05 kg of nanofiltrate from the extraction port of the RNM-1812G nanofiltration membrane separation system. The content of N, N-bis(carboxymethyl)-L-glutamate tetrasodium was 37.44% after sampling and detection;

[0125] Step 13, controlling the temperature of the concentrator to 45°C and the pressure to -0.098MPa, vacuum concentrating the nanofiltrate to obtain 31.66kg of concentrated liquid, and collecting 14.36kg of concentrated water;

[0126] Step 14, filling SWJS-101 activated carbon in the adsorber, the filling volume is 93% of the volume of the adsorber, controlling the operating temperature of the adsorber to 65 ° C, and continuously introducing the concentrate into the adsorber at a feed rate of 5 kg / h for adsorption and decolorization to obtain 31.36 kg of N, N-bis (carboxymethyl) -L-glutamate tetrasodium aqueous solution product, sampling and testing N, N-bis (carboxymethyl) -L-glutamate tetrasodium content of 55.58%, liquid phase purity 99.97%, NTA-3Na content 0.0022wt%, platinum cobalt chromaticity 44, 20 ° C dynamic viscosity of 395 centipoise, accounting N, N-bis (carboxymethyl) -L-glutamate tetrasodium pure yield is 95.963%.

[0127] Example 4

[0128] This embodiment provides a production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, comprising the following steps:

[0129] Step 1, controlling the operating temperature of the RNM-303 nanofiltration membrane separation system to 20°C and the working pressure to 30.0 bar, continuously introducing a 32.8wt% N,N-bis(cyanomethyl)-L-sodium glutamate reaction solution into the RNM-303 nanofiltration membrane separation system at a rate of 4.171kg / h to obtain 4.111kg / h of N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution, wherein the formaldehyde concentration is 0.0021wt%, and the hydroxyacetonitrile concentration is 0.0024wt%;

[0130] Step 2, controlling the temperature of the primary reactor to 33° C. and the pressure to 0.003 MPa, and continuously introducing the above-mentioned N, N-bis(cyanomethyl)-L-glutamate sodium pretreatment liquid at a rate of 1.9733 kg / h and a 50% sodium hydroxide solution at a rate of 1.2491 kg / h into the primary reactor for alkaline hydrolysis, and controlling the residence time of the material in the primary reactor to be 1.5 h;

[0131] Step 3, controlling the temperature of the secondary reactor to 43 ° C and the pressure to 0.003 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the secondary reactor at a feed rate of 1.2333 kg / h, and continuously introducing the primary reaction liquid extracted from the primary reactor into the secondary reactor at a feed rate of 3.222 kg / h, and controlling the residence time of the material in the secondary reactor to 1.5h;

[0132] Step 4, controlling the temperature of the tertiary reactor to 53 ° C and the pressure to 0.003 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the tertiary reactor at a feed rate of 0.6167 kg / h, and continuously introducing the secondary reaction liquid extracted from the secondary reactor into the tertiary reactor at a feed rate of 4.455 kg / h, and controlling the residence time of the material in the tertiary reactor to 1.5h;

[0133] Step 5, controlling the temperature of the fourth-stage reactor to 63 ° C and the pressure to 0.003 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the fourth-stage reactor at a feed rate of 0.2878 kg / h, and continuously introducing the third-stage reaction liquid extracted from the third-stage reactor into the fourth-stage reactor at a feed rate of 5.068 kg / h, and controlling the residence time of the material in the fourth-stage reactor to be 1.5h;

[0134] Step 6, controlling the temperature of the first-stage insulator to 65°C and the pressure to 0.003MPa, continuously introducing the fourth-stage reaction liquid extracted from the fourth-stage reactor into the first-stage insulator at a feed rate of 5.35kg / h for insulation, and at the same time, continuously introducing 15wt% hydrogen peroxide into the first-stage insulator at a feed rate of 0.0104kg / h, and controlling the residence time of the material in the first-stage insulator to be 1.5h;

[0135] Step 7: Control the temperature of the secondary insulator to 75°C and the pressure to 0.003MPa, continuously introduce the insulation liquid from the primary insulator into the secondary insulator at a feed rate of 5.348kg / h for insulation, control the residence time of the material in the secondary insulator to 1.5h, and monitor the exhaust rate collected at the steam outlet of the secondary insulator to be 0.0591kg / h;

[0136] Step 8, control the temperature of the third-stage insulator to 85°C and the pressure to 0.02MPa, continuously introduce the insulation liquid from the second-stage insulator into the third-stage insulator at a feed rate of 5.266kg / h for insulation, control the residence time of the material in the third-stage insulator to 1.5h, and monitor the exhaust rate collected at the steam outlet of the third-stage insulator to be 0.0781kg / h;

[0137] Step nine, control the temperature of the fourth-stage insulator to 95°C and the pressure to 0.021MPa, continuously introduce the insulation liquid from the third-stage insulator into the fourth-stage insulator at a feed rate of 5.167kg / h for insulation, control the residence time of the material in the fourth-stage insulator to 1.5h, and monitor the exhaust rate collected at the steam outlet of the fourth-stage insulator to be 0.2168kg / h;

[0138] Step 10, control the temperature of the five-stage insulator to 105°C and the pressure to 0.02MPa, continuously introduce the insulation liquid from the four-stage insulator into the five-stage insulator at a feed rate of 4.928kg / h for insulation, control the residence time of the material in the five-stage insulator to 1.5h, and monitor the exhaust rate collected at the steam outlet of the five-stage insulator to be 0.781kg / h;

[0139] Step 11, continuously collect 41.38kg of insulation liquid produced from the five-stage insulator for 10 hours, sample and test the sodium hydroxide content in the insulation liquid to be 0.336%. Control the operating temperature of the EX-3BT electrodialysis separation system to 40°C and the operating pressure to 0.02MPa, and continuously introduce the insulation liquid produced from the five-stage insulator into the EX-3BT electrodialysis separation system at a feed rate of 4kg / h, control the pH value of the material outlet of the EX-3BT electrodialysis separation system to be 10.10, and produce 41.10kg of liquid;

[0140] Step 12, controlling the operating temperature of the RNM-1812G nanofiltration membrane separation system to 30°C and the operating pressure to 30.0 bar, continuously introducing the material extracted from the EX-3BT electrodialysis separation system into the RNM-1812G nanofiltration membrane separation system at a feed rate of 4 kg / h, and obtaining 38.95 kg of nanofiltrate from the extraction port of the RNM-1812G nanofiltration membrane separation system. The content of N, N-bis(carboxymethyl)-L-glutamate tetrasodium was sampled and tested to be 43.39%;

[0141] Step 13, controlling the temperature of the concentrator to 50°C and the pressure to -0.096MPa, vacuum concentrating the nanofiltrate to obtain 30.33kg of concentrated liquid, and collecting 8.40kg of concentrated water;

[0142] Step 14, filling SWJS-101 activated carbon in the adsorber, the filling volume is 95% of the volume of the adsorber, controlling the operating temperature of the adsorber to 70 ° C, and continuously introducing the concentrate into the adsorber at a feed rate of 5 kg / h for adsorption and decolorization to obtain 30.01 kg of N, N-bis (carboxymethyl) -L-glutamate tetrasodium aqueous solution product, sampling and testing N, N-bis (carboxymethyl) -L-glutamate tetrasodium content of 55.56%, liquid phase purity 99.958%, NTA-3Na content 0.0025wt%, platinum cobalt chromaticity 43, 20 ° C dynamic viscosity of 391 centipoise, accounting N, N-bis (carboxymethyl) -L-glutamate tetrasodium pure yield is 91.986%.

[0143] Comparative Example 1

[0144] This comparative example provides a production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, which is different from Example 1 in that step 11 and step 12 are omitted, and specifically comprises the following steps:

[0145] Step 1, controlling the operating temperature of the RNM-303 nanofiltration membrane separation system to 10.2° C. and the working pressure to 25.1 bar, continuously introducing a 32.8wt% N,N-bis(cyanomethyl)-L-sodium glutamate reaction solution into the RNM-303 nanofiltration membrane separation system at a rate of 4.155kg / h to obtain 4.105kg / h of N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution, wherein the formaldehyde concentration is detected to be 0.00205wt%, and the concentration of hydroxyacetonitrile is 0.00211wt%;

[0146] Step 2, controlling the temperature of the primary reactor to 28.1° C. and the pressure to 0.001 MPa, and continuously introducing the above-mentioned N, N-bis(cyanomethyl)-L-glutamate sodium pretreatment liquid at a rate of 1.97 kg / h and a 50% sodium hydroxide solution at a mass concentration of 1.235 kg / h into the primary reactor for alkaline hydrolysis, and controlling the residence time of the material in the primary reactor to 1.2 h;

[0147] Step 3, controlling the temperature of the secondary reactor to 38.3 ° C and the pressure to 0.001 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment solution into the secondary reactor at a feed rate of 1.232 kg / h, and continuously introducing the primary reaction solution extracted from the primary reactor into the secondary reactor at a feed rate of 3.196 kg / h, and controlling the residence time of the material in the secondary reactor to 1.2h;

[0148] Step 4, controlling the temperature of the tertiary reactor to 48.5°C and the pressure to 0.001MPa, continuously introducing the N,N-bis(cyanomethyl)-L-glutamate sodium pretreatment solution into the tertiary reactor at a feed rate of 0.616kg / h, and continuously introducing the secondary reaction solution extracted from the secondary reactor into the tertiary reactor at a feed rate of 4.42kg / h, and controlling the residence time of the material in the tertiary reactor to be 1.2h;

[0149] Step 5, controlling the temperature of the fourth-stage reactor to 58.2° C. and the pressure to 0.001 MPa, continuously introducing the N,N-bis(cyanomethyl)-L-glutamate sodium pretreatment solution into the fourth-stage reactor at a feed rate of 0.286 kg / h, and continuously introducing the third-stage reaction solution extracted from the third-stage reactor into the fourth-stage reactor at a feed rate of 5.024 kg / h, and controlling the residence time of the material in the fourth-stage reactor to be 1.2 h;

[0150] Step 6, controlling the temperature of the first-stage insulator to 60°C and the pressure to 0.003MPa, continuously introducing the fourth-stage reaction liquid extracted from the fourth-stage reactor into the first-stage insulator at a feed rate of 5.306kg / h for insulation, and at the same time, continuously introducing 10.2wt% hydrogen peroxide into the first-stage insulator at a feed rate of 0.0164kg / h, and controlling the residence time of the material in the first-stage insulator to be 1.2h;

[0151] Step 7: Control the temperature of the secondary insulator to 70.2°C and the pressure to 0.003MPa, continuously introduce the insulation liquid from the primary insulator into the secondary insulator at a feed rate of 5.322kg / h for insulation, control the residence time of the material in the secondary insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the secondary insulator to be 0.055kg / h;

[0152] Step 8, control the temperature of the third-stage insulator to 80.5°C and the pressure to 0.015MPa, continuously introduce the insulation liquid from the second-stage insulator into the third-stage insulator at a feed rate of 5.265kg / h for insulation, control the residence time of the material in the third-stage insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the third-stage insulator to be 0.075kg / h;

[0153] Step nine, control the temperature of the fourth-stage insulator to 90°C and the pressure to 0.015MPa, continuously introduce the insulation liquid from the third-stage insulator into the fourth-stage insulator at a feed rate of 5.185kg / h for insulation, control the residence time of the material in the fourth-stage insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the fourth-stage insulator to be 0.187kg / h;

[0154] Step 10, control the temperature of the five-stage insulator to 100°C and the pressure to 0.018MPa, continuously introduce the insulation liquid from the four-stage insulator into the five-stage insulator at a feed rate of 4.99kg / h for insulation, control the residence time of the material in the five-stage insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the five-stage insulator to be 0.715kg / h;

[0155] Step 11, continuously collecting 42.68 kg of insulation liquid extracted from the five-stage insulation device for 10 hours, sampling and testing the content of N, N-bis (carboxymethyl) -L-glutamate tetrasodium in the insulation liquid to be 40.52%, the content of sodium hydroxide to be 0.223%, controlling the temperature of the concentrator to 40.2 ° C, the pressure to -0.099 MPa, vacuum concentrating the insulation liquid to obtain 31.01 kg of concentrated liquid, and collecting 11.32 kg of concentrated water;

[0156] Step twelve, filling SWJS-101 activated carbon in the adsorber, the filling volume is 90% of the volume of the adsorber, controlling the operating temperature of the adsorber to 60.1°C, and continuously introducing the concentrate into the adsorber at a feed rate of 5kg / h for adsorption and decolorization to obtain 30.66kg of N,N-bis(carboxymethyl)-L-glutamate tetrasodium aqueous solution product, sampling and detecting N,N-bis(carboxymethyl)-L-glutamate tetrasodium content of 55.54%, liquid phase purity of 98.61%, NTA-3Na content of 0.0021wt%, platinum cobalt chromaticity of 46, 20°C dynamic viscosity of 1956.3 centipoise, and the pure yield of N,N-bis(carboxymethyl)-L-glutamate tetrasodium is 93.035%.

[0157] Comparative Example 2

[0158] This comparative example provides a production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, which is different from Example 2 only in that the gradient heat preservation is changed to heat preservation at a constant temperature, and specifically comprises the following steps:

[0159] Step 1, controlling the operating temperature of the RNM-303 nanofiltration membrane separation system to 20° C. and the working pressure to 30.0 bar, continuously introducing a 32.8wt% N,N-bis(cyanomethyl)-L-sodium glutamate reaction solution into the RNM-303 nanofiltration membrane separation system at a rate of 4.16kg / h to obtain 4.1kg / h of N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution, wherein the formaldehyde concentration is detected to be 0.0021wt%, and the concentration of hydroxyacetonitrile is 0.0022wt%;

[0160] Step 2, controlling the temperature of the primary reactor to 33.1° C. and the pressure to 0.002 MPa, and continuously introducing the above-mentioned N, N-bis(cyanomethyl)-L-glutamate sodium pretreatment liquid at a rate of 1.968 kg / h and a 50% sodium hydroxide solution at a rate of 1.246 kg / h into the primary reactor for alkaline hydrolysis, and controlling the residence time of the material in the primary reactor to 1.5 h;

[0161] Step 3, controlling the temperature of the secondary reactor to 43.3 ° C and the pressure to 0.003 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment solution into the secondary reactor at a feed rate of 1.23 kg / h, and continuously introducing the primary reaction solution extracted from the primary reactor into the secondary reactor at a feed rate of 3.206 kg / h, and controlling the residence time of the material in the secondary reactor to 1.5h;

[0162] Step 4, controlling the temperature of the tertiary reactor to 53.2° C. and the pressure to 0.003 MPa, continuously introducing the N,N-bis(cyanomethyl)-L-glutamate sodium pretreatment solution into the tertiary reactor at a feed rate of 0.615 kg / h, and continuously introducing the secondary reaction solution extracted from the secondary reactor into the tertiary reactor at a feed rate of 4.424 kg / h, and controlling the residence time of the material in the tertiary reactor to be 1.5 h;

[0163] Step 5, controlling the temperature of the fourth-stage reactor to 63 ° C and the pressure to 0.003 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the fourth-stage reactor at a feed rate of 0.287 kg / h, and continuously introducing the third-stage reaction liquid extracted from the third-stage reactor into the fourth-stage reactor at a feed rate of 5.015 kg / h, and controlling the residence time of the material in the fourth-stage reactor to be 1.5h;

[0164] Step 6, controlling the temperature of the insulator to 105°C and the pressure to 0.02MPa, continuously introducing the fourth-stage reaction liquid extracted from the fourth-stage reactor into the insulator at a feed rate of 5.291kg / h for heat preservation and water collection, and at the same time, continuously introducing 14.9wt% hydrogen peroxide into the first-stage insulator at a feed rate of 0.01045kg / h, and controlling the residence time of the material in the first-stage insulator to be 7.5h;

[0165] Step 7: Continuously collect 41.48 kg of insulation liquid extracted from the five-stage insulator for 10 hours, and sample and test the sodium hydroxide content in the insulation liquid to be 0.324%. Control the operating temperature of the EX-3BT electrodialysis separation system to 39.9°C and the operating pressure to 0.02 MPa, and continuously introduce the insulation liquid extracted from the five-stage insulator into the EX-3BT electrodialysis separation system at a feed rate of 4 kg / h, and control the pH value of the material extraction port of the EX-3BT electrodialysis separation system to be 10.10, and the extracted liquid is 41.18 kg;

[0166] Step eight, controlling the operating temperature of the RNM-1812G nanofiltration membrane separation system to 29.6°C and the operating pressure to 30.0 bar, continuously introducing the material extracted from the EX-3BT electrodialysis separation system into the RNM-1812G nanofiltration membrane separation system at a feed rate of 4 kg / h, and obtaining 40.01 kg of nanofiltrate from the extraction port of the RNM-1812G nanofiltration membrane separation system, and sampling and detecting the content of tetrasodium N,N-bis(carboxymethyl)-L-glutamate to be 42.35%;

[0167] Step nine, controlling the temperature of the concentrator to 49.8°C and the pressure to -0.097MPa, vacuum concentrating the nanofiltrate to obtain 30.18kg of concentrated liquid, and collecting 9.45kg of concentrated water;

[0168] Step ten, filling SWJS-101 activated carbon in the adsorber, the filling volume is 95% of the volume of the adsorber, controlling the operating temperature of the adsorber to 69.8°C, and continuously introducing the concentrate into the adsorber at a feed rate of 5kg / h for adsorption and decolorization to obtain 29.04kg of N,N-bis(carboxymethyl)-L-glutamate tetrasodium aqueous solution product, sampling and detecting N,N-bis(carboxymethyl)-L-glutamate tetrasodium content of 55.56%, liquid phase purity of 97.69%, NTA-3Na content of 0.0048wt%, platinum cobalt chromaticity of 130, 20°C dynamic viscosity of 456 centipoise, and the pure yield of N,N-bis(carboxymethyl)-L-glutamate tetrasodium is 87.223%.

[0169] Comparative Example 3

[0170] This comparative example provides a production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, which is different from Example 3 in that step 1 is omitted, and specifically comprises the following steps:

[0171] Step 1, filtering the N, N-bis (cyanomethyl) -L-sodium glutamate reaction solution with a concentration of 32.8% at a rate of 4.125kg / h through a plate and frame filter to remove mechanical impurities therein, controlling the temperature of the primary reactor to 30 ° C, the pressure to 0.0018MPa, the filtered N, N-bis (cyanomethyl) -L-sodium glutamate pretreatment solution at a rate of 1.980kg / h, and the mass concentration of 32% sodium hydroxide solution at a rate of 1.949kg / h are continuously introduced into the primary reactor for alkaline hydrolysis, and the residence time of the material in the primary reactor is controlled to be 1.4h;

[0172] Step 2, controlling the temperature of the secondary reactor to 40°C and the pressure to 0.0021MPa, continuously introducing the N,N-bis(cyanomethyl)-L-glutamate sodium pretreatment solution into the secondary reactor at a feed rate of 1.238kg / h, and continuously introducing the primary reaction solution extracted from the primary reactor into the secondary reactor at a feed rate of 3.926kg / h, and controlling the residence time of the material in the secondary reactor to be 1.4h;

[0173] Step 3, controlling the temperature of the tertiary reactor to 50 ° C and the pressure to 0.0019 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the tertiary reactor at a feed rate of 0.619 kg / h, and continuously introducing the secondary reaction liquid extracted from the secondary reactor into the tertiary reactor at a feed rate of 5.159 kg / h, and controlling the residence time of the material in the tertiary reactor to be 1.4h;

[0174] Step 4, controlling the temperature of the fourth-stage reactor to 60° C. and the pressure to 0.002 MPa, continuously introducing the N,N-bis(cyanomethyl)-L-glutamate sodium pretreatment liquid into the fourth-stage reactor at a feed rate of 0.288 kg / h, and continuously introducing the third-stage reaction liquid extracted from the third-stage reactor into the fourth-stage reactor at a feed rate of 5.765 kg / h, and controlling the residence time of the material in the fourth-stage reactor to be 1.4 h;

[0175] Step 5, controlling the temperature of the first-stage insulator to 63°C and the pressure to 0.0019 MPa, continuously introducing the fourth-stage reaction liquid extracted from the fourth-stage reactor into the first-stage insulator at a feed rate of 6.049 kg / h for insulation, and at the same time, continuously introducing 13.1wt% hydrogen peroxide into the first-stage insulator at a feed rate of 0.01236 kg / h, and controlling the residence time of the material in the first-stage insulator to be 1.4 h;

[0176] Step 6: Control the temperature of the secondary insulator to 73°C and the pressure to 0.0021MPa, continuously introduce the insulation liquid from the primary insulator into the secondary insulator at a feed rate of 6.060kg / h for insulation, control the residence time of the material in the secondary insulator to 1.4h, and monitor the exhaust rate collected at the steam outlet of the secondary insulator to be 0.059kg / h;

[0177] Step 7: Control the temperature of the third-stage insulator to 83°C and the pressure to 0.016MPa, continuously introduce the insulation liquid from the second-stage insulator into the third-stage insulator at a feed rate of 5.985kg / h for insulation, control the residence time of the material in the third-stage insulator to 1.4h, and monitor the exhaust rate collected at the steam outlet of the third-stage insulator to be 0.077kg / h;

[0178] Step 8, control the temperature of the fourth-stage insulator to 93°C and the pressure to 0.016MPa, continuously introduce the insulation liquid from the third-stage insulator into the fourth-stage insulator at a feed rate of 5.893kg / h for insulation, control the residence time of the material in the fourth-stage insulator to 1.4h, and monitor the exhaust rate collected at the steam outlet of the fourth-stage insulator to be 0.206kg / h;

[0179] Step nine, control the temperature of the five-stage insulator to 103°C and the pressure to 0.017MPa, continuously introduce the insulation liquid from the four-stage insulator into the five-stage insulator at a feed rate of 5.675kg / h for insulation, control the residence time of the material in the five-stage insulator to 1.4h, and monitor the exhaust rate collected at the steam outlet of the five-stage insulator to be 0.748kg / h;

[0180] Step 10: Continuously collect 49.15 kg of insulation liquid extracted from the five-stage insulator for 10 hours, and sample and test the sodium hydroxide content in the insulation liquid to be 0.256%. Control the operating temperature of the EX-3BT electrodialysis separation system to 35°C and the operating pressure to 0.014 MPa, and continuously introduce the insulation liquid extracted from the five-stage insulator into the EX-3BT electrodialysis separation system at a feed rate of 4 kg / h, and control the pH value of the material extraction port of the EX-3BT electrodialysis separation system to be 10.02, and the extracted liquid is 48.75 kg;

[0181] Step 12, controlling the operating temperature of the RNM-1812G nanofiltration membrane separation system to 26.8°C and the operating pressure to 27.0 bar, continuously introducing the material extracted from the EX-3BT electrodialysis separation system into the RNM-1812G nanofiltration membrane separation system at a feed rate of 4 kg / h, and obtaining 46.01 kg of nanofiltrate from the extraction port of the RNM-1812G nanofiltration membrane separation system, and sampling and detecting the content of tetrasodium N,N-bis(carboxymethyl)-L-glutamate to be 36.74%;

[0182] Step 13, controlling the temperature of the concentrator to 45°C and the pressure to -0.099 MPa, vacuum concentrating the nanofiltrate to obtain 30.12 kg of concentrated liquid, and collecting 14.45 kg of concentrated water;

[0183] Step 14, filling SWJS-101 activated carbon in the adsorber, the filling volume is 93% of the volume of the adsorber, controlling the operating temperature of the adsorber to 65 ° C, and continuously introducing the concentrate into the adsorber at a feed rate of 5 kg / h for adsorption and decolorization to obtain 29.78 kg of N, N-bis (carboxymethyl) -L-glutamate tetrasodium aqueous solution product, sampling and testing N, N-bis (carboxymethyl) -L-glutamate tetrasodium content of 55.55%, liquid phase purity of 98.78%, NTA-3Na content of 0.094wt%, platinum cobalt chromaticity of 48, 20 ° C dynamic viscosity of 428 centipoise, accounting N, N-bis (carboxymethyl) -L-glutamate tetrasodium pure yield is 91.195%.

[0184] Comparative Example 4

[0185] This comparative example provides a production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, which is different from Example 1 in that only one alkaline hydrolysis reaction is performed, and specifically comprises the following steps:

[0186] Step 1, controlling the operating temperature of the RNM-303 nanofiltration membrane separation system to 10°C and the working pressure to 25.0 bar, continuously introducing a 32.8wt% N,N-bis(cyanomethyl)-L-sodium glutamate reaction solution into the RNM-303 nanofiltration membrane separation system at a rate of 4.153kg / h to obtain 4.103kg / h of N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution, wherein the formaldehyde concentration is detected to be 0.0021wt%, and the concentration of hydroxyacetonitrile is 0.0018wt%;

[0187] Step 2, controlling the temperature of the reactor to 58° C. and the pressure to 0.001 MPa, and continuously introducing the above-mentioned N, N-bis(cyanomethyl)-L-glutamate sodium pretreatment liquid at a rate of 4.103 kg / h and a 50% sodium hydroxide solution at a mass concentration of 1.235 kg / h into the reactor for alkaline hydrolysis, and controlling the residence time of the material in the primary reactor to 4.8 h;

[0188] Step 3, controlling the temperature of the first-stage insulator to 60°C and the pressure to 0.003MPa, continuously introducing the reaction liquid extracted from the reactor into the first-stage insulator at a feed rate of 5.331kg / h for insulation, and at the same time, continuously introducing 10.1wt% hydrogen peroxide into the first-stage insulator at a feed rate of 0.01636kg / h, and controlling the residence time of the material in the first-stage insulator to be 1.2h;

[0189] Step 4: Control the temperature of the secondary insulator to 70°C and the pressure to 0.003MPa, continuously introduce the insulation liquid from the primary insulator into the secondary insulator at a feed rate of 5.344kg / h for insulation, control the residence time of the material in the secondary insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the secondary insulator to be 0.057kg / h;

[0190] Step 5: Control the temperature of the third-stage insulator to 80°C and the pressure to 0.012MPa, continuously introduce the insulation liquid from the second-stage insulator into the third-stage insulator at a feed rate of 5.281kg / h for insulation, control the residence time of the material in the third-stage insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the third-stage insulator to be 0.075kg / h;

[0191] Step 6: Control the temperature of the fourth-stage insulator to 90°C and the pressure to 0.011MPa, continuously introduce the insulation liquid from the third-stage insulator into the fourth-stage insulator at a feed rate of 5.202kg / h for insulation, control the residence time of the material in the fourth-stage insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the fourth-stage insulator to be 0.187kg / h;

[0192] Step 7: Control the temperature of the five-stage insulator to 100°C and the pressure to 0.022MPa, continuously introduce the insulation liquid from the four-stage insulator into the five-stage insulator at a feed rate of 5.012kg / h for insulation, control the residence time of the material in the five-stage insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the five-stage insulator to be 0.721kg / h;

[0193] Step 8: Continuously collect 42.85 kg of insulation liquid extracted from the five-stage insulator for 10 hours, and sample and test the sodium hydroxide content in the insulation liquid to be 0.217%. Control the operating temperature of the EX-3BT electrodialysis separation system to 30°C and the operating pressure to 0.011 MPa, and continuously introduce the insulation liquid extracted from the five-stage insulator into the EX-3BT electrodialysis separation system at a feed rate of 4 kg / h, and control the pH value of the material extraction port of the EX-3BT electrodialysis separation system to be 9.91, and the extracted liquid is 42.69 kg;

[0194] Step 12, controlling the operating temperature of the RNM-1812G nanofiltration membrane separation system to 25°C and the operating pressure to 25.1 bar, continuously introducing the material extracted from the EX-3BT electrodialysis separation system into the RNM-1812G nanofiltration membrane separation system at a feed rate of 4 kg / h, and obtaining 40.81 kg of nanofiltrate from the extraction port of the RNM-1812G nanofiltration membrane separation system, and sampling and detecting the content of tetrasodium N,N-bis(carboxymethyl)-L-glutamate to be 40.64%;

[0195] Step 13, controlling the temperature of the concentrator to 40°C and the pressure to -0.099 MPa, vacuum concentrating the nanofiltrate to obtain 29.76 kg of concentrated liquid, and collecting 10.23 kg of concentrated water;

[0196] Step 14, filling SWJS-101 activated carbon in the adsorber, the filling volume is 90% of the volume of the adsorber, controlling the operating temperature of the adsorber to 60 ° C, and continuously introducing the concentrate into the adsorber at a feed rate of 5 kg / h for adsorption and decolorization to obtain 28.76 kg of N, N-bis (carboxymethyl) -L-glutamate tetrasodium aqueous solution product, sampling and testing N, N-bis (carboxymethyl) -L-glutamate tetrasodium content of 55.53%, liquid phase purity of 98.46%, NTA-3Na content of 0.0065wt%, platinum cobalt chromaticity of 110, 20 ° C dynamic viscosity of 462 centipoise, accounting N, N-bis (carboxymethyl) -L-glutamate tetrasodium pure yield is 87.163%.

[0197] Comparative Example 5

[0198] This comparative example provides a production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, which is different from Example 2 only in that the SWJS-101 activated carbon of the adsorber is replaced with SWJS-103 activated carbon, and comprises the following steps:

[0199] Step 1, controlling the operating temperature of the RNM-303 nanofiltration membrane separation system to 20°C and the working pressure to 30.0 bar, continuously introducing the N,N-bis(cyanomethyl)-L-sodium glutamate reaction solution with a concentration of 32.8wt% into the RNM-303 nanofiltration membrane separation system at a rate of 4.165kg / h, obtaining 4.106kg / h of N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution, detecting the formaldehyde concentration therein to be 0.0023wt%, and the concentration of hydroxyacetonitrile to be 0.0024wt%;

[0200] Step 2, controlling the temperature of the primary reactor to 33° C. and the pressure to 0.003 MPa, introducing the above-mentioned sodium N,N-bis(cyanomethyl)-L-glutamate pretreatment liquid at a rate of 1.971 kg / h and a sodium hydroxide solution with a mass concentration of 50% at a rate of 1.248 kg / h into the primary reactor for alkaline hydrolysis, and controlling the residence time of the material in the primary reactor to be 1.5 h;

[0201] Step 3, controlling the temperature of the secondary reactor to 43 ° C and the pressure to 0.003 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment solution into the secondary reactor at a feed rate of 1.232 kg / h, and continuously introducing the primary reaction solution extracted from the primary reactor into the secondary reactor at a feed rate of 3.207 kg / h, and controlling the residence time of the material in the secondary reactor to 1.5h;

[0202] Step 4, controlling the temperature of the tertiary reactor to 53 ° C and the pressure to 0.003 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the tertiary reactor at a feed rate of 0.616 kg / h, and continuously introducing the secondary reaction liquid extracted from the secondary reactor into the tertiary reactor at a feed rate of 4.42 kg / h, and controlling the residence time of the material in the tertiary reactor to 1.5h;

[0203] Step 5, controlling the temperature of the fourth-stage reactor to 63 ° C and the pressure to 0.003 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the fourth-stage reactor at a feed rate of 0.287 kg / h, and continuously introducing the third-stage reaction liquid extracted from the third-stage reactor into the fourth-stage reactor at a feed rate of 5.024 kg / h, and controlling the residence time of the material in the fourth-stage reactor to be 1.5h;

[0204] Step 6, controlling the temperature of the first-stage insulator to 65°C and the pressure to 0.003MPa, continuously introducing the fourth-stage reaction liquid extracted from the fourth-stage reactor into the first-stage insulator at a feed rate of 5.301kg / h for insulation, and at the same time, continuously introducing 14.95wt% hydrogen peroxide into the first-stage insulator at a feed rate of 0.0104kg / h, and controlling the residence time of the material in the first-stage insulator to be 1.5h;

[0205] Step 7: Control the temperature of the secondary insulator to 75°C and the pressure to 0.003MPa, continuously introduce the insulation liquid from the primary insulator into the secondary insulator at a feed rate of 5.311kg / h for insulation, control the residence time of the material in the secondary insulator to 1.5h, and monitor the exhaust rate collected at the steam outlet of the secondary insulator to be 0.0593kg / h;

[0206] Step 8, control the temperature of the third-stage insulator to 85°C and the pressure to 0.02MPa, continuously introduce the insulation liquid from the second-stage insulator into the third-stage insulator at a feed rate of 5.249kg / h for insulation, control the residence time of the material in the third-stage insulator to 1.5h, and monitor the exhaust rate collected at the steam outlet of the third-stage insulator to be 0.077kg / h;

[0207] Step nine, control the temperature of the fourth-stage insulator to 95°C and the pressure to 0.02MPa, continuously introduce the insulation liquid from the third-stage insulator into the fourth-stage insulator at a feed rate of 5.157kg / h for insulation, control the residence time of the material in the fourth-stage insulator to 1.5h, and monitor the exhaust rate collected at the steam outlet of the fourth-stage insulator to be 0.2183kg / h;

[0208] Step 10, control the temperature of the five-stage insulator to 105°C and the pressure to 0.02MPa, continuously introduce the insulation liquid from the four-stage insulator into the five-stage insulator at a feed rate of 4.929kg / h for insulation, control the residence time of the material in the five-stage insulator to 1.5h, and monitor the exhaust rate collected at the steam outlet of the five-stage insulator to be 0.7797kg / h;

[0209] Step 11, continuously collect 41.39kg of insulation liquid produced from the five-stage insulator for 10 hours, sample and test the sodium hydroxide content in the insulation liquid to be 0.335%. Control the operating temperature of the EX-3BT electrodialysis separation system to 40°C and the operating pressure to 0.02MPa, and continuously introduce the insulation liquid produced from the five-stage insulator into the EX-3BT electrodialysis separation system at a feed rate of 4kg / h, control the pH value of the material production outlet of the EX-3BT electrodialysis separation system to be 10.09, and produce 41.12kg of liquid;

[0210] Step 12, controlling the operating temperature of the RNM-1812G nanofiltration membrane separation system to 30°C and the operating pressure to 30.0 bar, continuously introducing the material extracted from the EX-3BT electrodialysis separation system into the RNM-1812G nanofiltration membrane separation system at a feed rate of 4 kg / h, and obtaining 40.36 kg of nanofiltrate from the extraction port of the RNM-1812G nanofiltration membrane separation system, and sampling and detecting the content of tetrasodium N,N-bis(carboxymethyl)-L-glutamate to be 43.38%;

[0211] Step 13, controlling the temperature of the concentrator to 50°C and the pressure to -0.095MPa, vacuum concentrating the nanofiltrate to obtain 31.41kg of concentrated liquid, and collecting 8.61kg of concentrated water;

[0212] Step 14, fill SWJS-103 activated carbon in the adsorber, the filling volume is 95% of the volume of the adsorber, control the operating temperature of the adsorber to 70 ° C, and continuously introduce the concentrate into the adsorber at a feed rate of 5 kg / h for adsorption and decolorization to obtain 31.06 kg of N, N-bis (carboxymethyl) -L-glutamate tetrasodium aqueous solution product, sampling and detection of N, N-bis (carboxymethyl) -L-glutamate tetrasodium content of 55.53%, liquid phase purity of 99.84%, NTA-3Na content of 0.0024wt%, platinum cobalt chromaticity of 105, 20 ° C dynamic viscosity of 423 centipoise, accounting N, N-bis (carboxymethyl) -L-glutamate tetrasodium pure yield is 95.178%.

[0213] Comparative Example 6

[0214] This comparative example provides a production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, which is different from Example 1 only in that the RNM-303 nanofiltration membrane in step 1 is replaced with a RNM-301 nanofiltration membrane, comprising the following steps:

[0215] Step 1, controlling the operating temperature of the RNM-301 nanofiltration membrane separation system to 10°C and the working pressure to 25.0 bar, continuously introducing the N,N-bis(cyanomethyl)-L-sodium glutamate reaction solution with a concentration of 32.8wt% into the RNM-301 nanofiltration membrane separation system at a rate of 4.151kg / h, obtaining 3.6kg / h of N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution, detecting the formaldehyde concentration therein to be 0.0023wt%, and the concentration of hydroxyacetonitrile to be 0.0021wt%;

[0216] Step 2, controlling the temperature of the primary reactor to 28° C. and the pressure to 0.001 MPa, and continuously introducing the above-mentioned N, N-bis(cyanomethyl)-L-glutamate sodium pretreatment liquid at a rate of 1.728 kg / h and a 50% sodium hydroxide solution at a rate of 1.083 kg / h into the primary reactor for alkaline hydrolysis, and controlling the residence time of the material in the primary reactor to be 1.2 h;

[0217] Step 3, controlling the temperature of the secondary reactor to 38 ° C and the pressure to 0.001 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment solution into the secondary reactor at a feed rate of 1.08 kg / h, and continuously introducing the primary reaction solution extracted from the primary reactor into the secondary reactor at a feed rate of 2.81 kg / h, and controlling the residence time of the material in the secondary reactor to 1.2h;

[0218] Step 4, controlling the temperature of the tertiary reactor to 48 ° C and the pressure to 0.001 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the tertiary reactor at a feed rate of 0.54 kg / h, and continuously introducing the secondary reaction liquid extracted from the secondary reactor into the tertiary reactor at a feed rate of 3.88 kg / h, and controlling the residence time of the material in the tertiary reactor to be 1.2h;

[0219] Step 5, controlling the temperature of the fourth-stage reactor to 58 ° C and the pressure to 0.001 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the fourth-stage reactor at a feed rate of 0.252 kg / h, and continuously introducing the third-stage reaction liquid extracted from the third-stage reactor into the fourth-stage reactor at a feed rate of 4.417 kg / h, and controlling the residence time of the material in the fourth-stage reactor to be 1.2h;

[0220] Step 6, controlling the temperature of the first-stage insulator to 60°C and the pressure to 0.003MPa, continuously introducing the fourth-stage reaction liquid extracted from the fourth-stage reactor into the first-stage insulator at a feed rate of 4.666kg / h for insulation, and at the same time, continuously introducing 10wt% hydrogen peroxide into the first-stage insulator at a feed rate of 0.01435kg / h, and controlling the residence time of the material in the first-stage insulator to be 1.2h;

[0221] Step 7: Control the temperature of the secondary insulator to 70°C and the pressure to 0.003MPa, continuously introduce the insulation liquid from the primary insulator into the secondary insulator at a feed rate of 4.678kg / h for insulation, control the residence time of the material in the secondary insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the secondary insulator to be 0.049kg / h;

[0222] Step 8, control the temperature of the third-stage insulator to 80°C and the pressure to 0.01MPa, continuously introduce the insulation liquid from the second-stage insulator into the third-stage insulator at a feed rate of 4.628kg / h for insulation, control the residence time of the material in the third-stage insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the third-stage insulator to be 0.065kg / h;

[0223] Step nine, control the temperature of the fourth-stage insulator to 90°C and the pressure to 0.01MPa, continuously introduce the insulation liquid from the third-stage insulator into the fourth-stage insulator at a feed rate of 4.561kg / h for insulation, control the residence time of the material in the fourth-stage insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the fourth-stage insulator to be 0.163kg / h;

[0224] Step 10, control the temperature of the five-stage insulator to 100°C and the pressure to 0.021MPa, continuously introduce the insulation liquid from the four-stage insulator into the five-stage insulator at a feed rate of 4.396kg / h for insulation, control the residence time of the material in the five-stage insulator to 1.2h, and monitor the exhaust rate collected at the steam outlet of the five-stage insulator to be 0.621kg / h;

[0225] Step 11, continuously collect 37.73kg of insulation liquid produced from the five-stage insulator for 10 hours, sample and test the sodium hydroxide content in the insulation liquid to 0.209%. Control the operating temperature of the EX-3BT electrodialysis separation system to 30°C and the operating pressure to 0.011MPa, and continuously introduce the insulation liquid produced from the five-stage insulator into the EX-3BT electrodialysis separation system at a feed rate of 4kg / h, control the pH value of the material outlet of the EX-3BT electrodialysis separation system to 9.90, and produce 37.61kg of liquid;

[0226] Step 12, controlling the operating temperature of the RNM-1812G nanofiltration membrane separation system to 25°C and the operating pressure to 25.0 bar, continuously introducing the material extracted from the EX-3BT electrodialysis separation system into the RNM-1812G nanofiltration membrane separation system at a feed rate of 4 kg / h, and obtaining 36.67 kg of nanofiltrate from the extraction port of the RNM-1812G nanofiltration membrane separation system. The content of N, N-bis(carboxymethyl)-L-glutamate tetrasodium was sampled and tested to be 41.455%;

[0227] Step 13, controlling the temperature of the concentrator to 40°C and the pressure to -0.1 MPa, vacuum concentrating the nanofiltrate to obtain 27.28 kg of concentrated liquid, and collecting 9.1 kg of concentrated water;

[0228] Step 14, filling SWJS-101 activated carbon in the adsorber, the filling volume is 90% of the volume of the adsorber, controlling the operating temperature of the adsorber to 60 ° C, and continuously introducing the concentrate into the adsorber at a feed rate of 5 kg / h for adsorption and decolorization to obtain 26.88 kg of N, N-bis (carboxymethyl) -L-glutamate tetrasodium aqueous solution product, sampling and testing N, N-bis (carboxymethyl) -L-glutamate tetrasodium content of 55.55%, liquid phase purity of 99.938%, NTA-3Na content of 0.0022wt%, platinum cobalt chromaticity of 43, 20 ° C dynamic viscosity of 388 centipoise, accounting N, N-bis (carboxymethyl) -L-glutamate tetrasodium pure yield of 82.758%.

[0229] Comparative Example 7

[0230] This comparative example provides a production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, which is different from Example 3 only in that the RNM-303 nanofiltration membrane in step 1 is replaced with 4A molecular sieve, and specifically comprises the following steps:

[0231] Step 1, controlling the operating temperature of the 4A molecular sieve adsorption system to be 15° C. and the working pressure to be 0.5 bar, continuously introducing a 32.8wt% N,N-bis(cyanomethyl)-L-sodium glutamate reaction solution into the 4A molecular sieve separation system at a rate of 4.185kg / h to obtain 4.18kg / h of N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment solution, wherein the formaldehyde concentration is detected to be 0.083wt%, and the concentration of hydroxyacetonitrile is 0.24wt%;

[0232] Step 2, controlling the temperature of the primary reactor to 30° C. and the pressure to 0.002 MPa, introducing the above-mentioned N, N-bis(cyanomethyl)-L-glutamate sodium pretreatment liquid at a rate of 2.006 kg / h and a 32% sodium hydroxide solution at a rate of 1.974 kg / h into the primary reactor for alkaline hydrolysis, and controlling the residence time of the material in the primary reactor to be 1.4 h;

[0233] Step 3, controlling the temperature of the secondary reactor to 40°C and the pressure to 0.002MPa, continuously introducing the N,N-bis(cyanomethyl)-L-glutamate sodium pretreatment solution into the secondary reactor at a feed rate of 1.254kg / h, and continuously introducing the primary reaction solution extracted from the primary reactor into the secondary reactor at a feed rate of 3.976kg / h, and controlling the residence time of the material in the secondary reactor to be 1.4h;

[0234] Step 4, controlling the temperature of the tertiary reactor to 50 ° C and the pressure to 0.002 MPa, continuously introducing the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment liquid into the tertiary reactor at a feed rate of 0.627 kg / h, and continuously introducing the secondary reaction liquid extracted from the secondary reactor into the tertiary reactor at a feed rate of 5.229 kg / h, and controlling the residence time of the material in the tertiary reactor to 1.4h;

[0235] Step 5, controlling the temperature of the fourth-stage reactor to 60° C. and the pressure to 0.002 MPa, continuously introducing the N,N-bis(cyanomethyl)-L-glutamate sodium pretreatment solution into the fourth-stage reactor at a feed rate of 0.293 kg / h, and continuously introducing the third-stage reaction solution extracted from the third-stage reactor into the fourth-stage reactor at a feed rate of 5.852 kg / h, and controlling the residence time of the material in the fourth-stage reactor to be 1.4 h;

[0236] Step 6, controlling the temperature of the first-stage insulator to 63°C and the pressure to 0.002MPa, continuously introducing the fourth-stage reaction liquid extracted from the fourth-stage reactor into the first-stage insulator at a feed rate of 6.142kg / h for insulation, and at the same time, continuously introducing 13wt% hydrogen peroxide into the first-stage insulator at a feed rate of 0.0126kg / h, and controlling the residence time of the material in the first-stage insulator to be 1.4h;

[0237] Step 7: Control the temperature of the secondary insulator to 73°C and the pressure to 0.002MPa, continuously introduce the insulation liquid from the primary insulator into the secondary insulator at a feed rate of 6.154kg / h for insulation, control the residence time of the material in the secondary insulator to 1.4h, and monitor the exhaust rate collected at the steam outlet of the secondary insulator to be 0.0584kg / h;

[0238] Step 8, control the temperature of the third-stage insulator to 83°C and the pressure to 0.015MPa, continuously introduce the insulation liquid from the second-stage insulator into the third-stage insulator at a feed rate of 6.094kg / h for insulation, control the residence time of the material in the third-stage insulator to 1.4h, and monitor the exhaust rate collected at the steam outlet of the third-stage insulator to be 0.0773kg / h;

[0239] Step nine, control the temperature of the fourth-stage insulator to 93°C and the pressure to 0.015MPa, continuously introduce the insulation liquid from the third-stage insulator into the fourth-stage insulator at a feed rate of 6.012kg / h for insulation, control the residence time of the material in the fourth-stage insulator to 1.4h, and monitor the exhaust rate collected at the steam outlet of the fourth-stage insulator to be 0.208kg / h;

[0240] Step 10, control the temperature of the five-stage insulator to 103°C and the pressure to 0.015MPa, continuously introduce the insulation liquid from the four-stage insulator into the five-stage insulator at a feed rate of 5.798kg / h for insulation, control the residence time of the material in the five-stage insulator to 1.4h, and monitor the exhaust rate collected at the steam outlet of the five-stage insulator to be 0.756kg / h;

[0241] Step 11, continuously collect 50.4 kg of insulation liquid produced from the five-stage insulator for 10 hours, sample and test the sodium hydroxide content in the insulation liquid to 0.255%. Control the operating temperature of the EX-3BT electrodialysis separation system to 35°C and the operating pressure to 0.014 MPa, and continuously introduce the insulation liquid produced from the five-stage insulator into the EX-3BT electrodialysis separation system at a feed rate of 4 kg / h, control the pH value of the material outlet of the EX-3BT electrodialysis separation system to 10.01, and produce 49.80 kg of liquid;

[0242] Step 12, controlling the operating temperature of the RNM-1812G nanofiltration membrane separation system to 27°C and the operating pressure to 27.1 bar, continuously introducing the material extracted from the EX-3BT electrodialysis separation system into the RNM-1812G nanofiltration membrane separation system at a feed rate of 4 kg / h, and obtaining 47.04 kg of nanofiltrate from the extraction port of the RNM-1812G nanofiltration membrane separation system, and sampling and detecting the content of tetrasodium N,N-bis(carboxymethyl)-L-glutamate to be 36.72%;

[0243] Step 13, controlling the temperature of the concentrator to 45°C and the pressure to -0.099 MPa, vacuum concentrating the nanofiltrate to obtain 31.02 kg of concentrated liquid, and collecting 15.4 kg of concentrated water;

[0244] Step 14, filling SWJS-101 activated carbon in the adsorber, the filling volume is 93% of the volume of the adsorber, controlling the operating temperature of the adsorber to 65 ° C, and continuously introducing the concentrate into the adsorber at a feed rate of 5 kg / h for adsorption and decolorization to obtain 30.69 kg of N, N-bis (carboxymethyl) -L-glutamate tetrasodium aqueous solution product, sampling and testing N, N-bis (carboxymethyl) -L-glutamate tetrasodium content of 55.56%, liquid phase purity 98.76%, NTA-3Na content 0.096wt%, platinum cobalt chromaticity 50, 20 ° C dynamic viscosity of 445 centipoise, accounting N, N-bis (carboxymethyl) -L-glutamate tetrasodium pure yield is 92.632%.

[0245] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, characterized in that: The following steps are involved: S1, filtering the N,N-bis(cyanomethyl)-L-glutamate sodium reaction solution through a nanofiltration membrane with a pore size of 0.5 nm to 1 nm to obtain a N,N-bis(cyanomethyl)-L-glutamate sodium pretreatment solution; S2, a part of the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment solution and all the liquid alkali are respectively continuously introduced into a multi-stage series reactor, wherein, after the reaction of each reactor is completed, the alkaline hydrolysis solution obtained in the reactor and a part of the N, N-bis (cyanomethyl) -L- glutamate sodium pretreatment solution are simultaneously and continuously introduced into the next reactor for step-by-step alkaline hydrolysis reaction to obtain an alkaline hydrolysis reaction solution; S3, continuously passing the alkaline hydrolysis reaction liquid and hydrogen peroxide into a multi-stage series insulator for gradient insulation to obtain an insulation liquid; S4, subjecting the insulation liquid to electrodialysis separation, nanofiltration, concentration, and activated carbon adsorption to remove impurities, to obtain an aqueous solution product of N,N-bis(carboxymethyl)-L-glutamate tetrasodium; the pore size of the activated carbon is 1nm to 30nm, and the iodine adsorption value is ≥1400mg / g; Wherein, the addition amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid of the primary reactor does not exceed 50% of the total amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid, the addition amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid of the secondary reactor does not exceed 30% of the total amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid, the addition amount of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid of the tertiary reactor to the Nth reactor decreases step by step, and the sum of the addition amounts of the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid of each reactor is 100%; The temperature of each reactor increases with the number of stages. The temperature of the first reactor does not exceed 40°C, the temperature of the second reactor does not exceed 50°C, and the temperature of the Nth reactor does not exceed 65°C. The temperature of each level of the insulator increases with the increase of the level. The temperature of the first level insulator does not exceed 65°C, the temperature of the second level insulator does not exceed 75°C, and the temperature of the Nth level insulator does not exceed 105°C.

2. The production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate according to claim 1, characterized in that: The number of stages of the multi-stage series reactor is 3 to 4; and / or The number of stages of the multi-stage series insulators is 5 to 6.

3. The production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate according to claim 2, characterized in that: The mass concentration of the liquid caustic soda is 30% to 50%; and / or The temperature of two adjacent reactors in the multi-stage series reactor is gradually increased by 5°C to 15°C; and / or The temperature of two connected stages of the multi-stage series heat preservation device increases step by step by 5°C to 15°C.

4. The production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate according to claim 3, characterized in that: When the number of stages of the multi-stage series reactor is three, the temperature of the first-stage reactor is 35°C to 40°C, the temperature of the second-stage reactor is 45°C to 50°C, and the temperature of the third-stage reactor is 58°C to 63°C; the pressure of each stage of the reactor is ≤0.003MPa, and the residence time of the material in each stage of the reactor is 1.6h to 2.0h; When the number of stages of the multi-stage series reactor is four, the temperature of the first-stage reactor is 28°C to 33°C, the temperature of the second-stage reactor is 38°C to 43°C, the temperature of the third-stage reactor is 48°C to 53°C, and the temperature of the fourth-stage reactor is 58°C to 63°C; the pressure of each stage of the reactor is ≤0.003MPa, and the residence time of the material in each stage of the reactor is 1.2h to 1.5h; When the number of stages of the multi-stage series insulator is five, the temperature of the first-stage insulator is 60℃~65℃, the temperature of the second-stage insulator is 70℃~75℃, the temperature of the third-stage insulator is 80℃~85℃, the temperature of the fourth-stage insulator is 90℃~95℃, and the temperature of the fifth-stage insulator is 100℃~105℃. The pressure of each stage of the insulator is 0.003MPa~0.02MPa, and the residence time of the material in each stage of the insulator is 1.2h~1.5h; When the number of stages of the multi-stage series insulator is six, the temperature of the first-stage insulator is 60℃~65℃, the temperature of the second-stage insulator is 65℃~70℃, the temperature of the third-stage insulator is 75℃~80℃, the temperature of the fourth-stage insulator is 85℃~90℃, the temperature of the fifth-stage insulator is 95℃~100℃, and the temperature of the sixth-stage insulator is 100℃~105℃. The pressure of each stage of the insulator is 0.003MPa~0.02MPa, and the residence time of the material in each stage of the insulator is 1.0h~1.25h.

5. The production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate according to any one of claims 1 to 4, characterized in that: The specific steps include: Step a, continuously passing the N,N-bis(cyanomethyl)-sodium L-glutamate reaction solution into a nanofiltration membrane separation system for nanofiltration to obtain a pretreated solution of N,N-bis(cyanomethyl)-sodium L-glutamate; Step b, continuously introducing the first part of the sodium N,N-bis(cyanomethyl)-L-glutamate pretreatment solution and all the liquid alkali into a primary reactor for alkaline hydrolysis reaction to obtain a primary reaction solution; Step c, simultaneously and continuously introducing the primary reaction liquid and the second part of the sodium N,N-bis(cyanomethyl)-L-glutamate pretreatment liquid into a secondary reactor for alkaline hydrolysis reaction to obtain a secondary reaction liquid; Step d, simultaneously and continuously introducing the secondary reaction liquid and the third part of the sodium N,N-bis(cyanomethyl)-L-glutamate pretreatment liquid into a tertiary reactor for alkaline hydrolysis reaction to obtain a tertiary reaction liquid; Step e, simultaneously and continuously introducing the tertiary reaction liquid and the remaining sodium N,N-bis(cyanomethyl)-L-glutamate pretreatment liquid into a fourth-stage reactor for alkaline hydrolysis reaction to obtain a fourth-stage reaction liquid; Step f, continuously passing the fourth-stage reaction liquid and hydrogen peroxide into a first-stage insulator for insulation to obtain a first-stage insulation liquid; Step g, sequentially and continuously passing the first-level insulation liquid into the second-level insulation device to the fifth-level insulation device for insulation, to obtain a fifth-level insulation liquid; Step h, continuously passing the five-stage insulation liquid into an electrodialysis separation system for separation to obtain an electrodialysis liquid; Step i, continuously passing the electrodialysis liquid into a nanofiltration membrane separation system for nanofiltration to obtain a nanofiltrate; Step j, continuously passing the nanofiltrate into a concentrator for concentration to obtain a concentrated solution; Step k, continuously passing the concentrated solution into an adsorber to obtain a tetrasodium N,N-bis(carboxymethyl)-L-glutamate aqueous solution product.

6. The production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate according to claim 5, characterized in that: In step a, the operating temperature of the nanofiltration membrane separation system is 10°C to 20°C, and the working pressure is 25 bar to 30 bar.

7. The production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate according to claim 5, characterized in that: The first part of the pretreatment solution of N,N-bis(cyanomethyl)-L-sodium glutamate is 45% to 50% of the total amount of the pretreatment solution of N,N-bis(cyanomethyl)-L-sodium glutamate, the second part of the pretreatment solution of N,N-bis(cyanomethyl)-L-sodium glutamate is 25% to 30% of the total amount of the pretreatment solution of N,N-bis(cyanomethyl)-L-sodium glutamate, and the third part of the pretreatment solution of N,N-bis(cyanomethyl)-L-sodium glutamate is 15% to 20% of the total amount of the pretreatment solution of N,N-bis(cyanomethyl)-L-sodium glutamate; and / or In step b, the liquid alkali is calculated as NaOH, the N,N-bis(cyanomethyl)-L-sodium glutamate pretreatment liquid is calculated as N,N-bis(cyanomethyl)-L-sodium glutamate, and the molar ratio of the liquid alkali to the total amount of N,N-bis(cyanomethyl)-L-sodium glutamate is 3.04:1 to 3.07:

1.

8. The production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate according to claim 5, characterized in that: In step f, the mass concentration of the hydrogen peroxide is 10% to 15%, and the mass ratio of H2O2 in the hydrogen peroxide to NaOH in the liquid caustic soda is 1:360 to 1:

400.

9. The production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate according to claim 5, characterized in that: In step h, the electrodialysis separation system is an EX-3BT electrodialysis separation system, whose operating temperature is 30°C to 40°C, the working pressure is 0.01MPa to 0.02MPa, the flow rate of the five-stage insulation liquid entering the electrodialysis separation system is 4kg / h to 8kg / h, and the discharge pH of the electrodialysis separation system is controlled to be 9.90 to 10.10; and / or In step i, the operating temperature of the nanofiltration membrane separation system is 25°C to 30°C, the working pressure is 25 bar to 30 bar, and the flow rate of the electrodialysis liquid entering the nanofiltration membrane separation system is 4 kg / h to 8 kg / h.

10. The production process of tetrasodium N,N-bis(carboxymethyl)-L-glutamate according to claim 5, characterized in that: In step j, the operating temperature of the concentrator is 40°C to 50°C and the pressure is -0.095MPa to -0.1MPa; and / or In step k, the filling volume of the activated carbon in the adsorber is 90% to 95% of the volume of the adsorber, and the operating temperature of the adsorber is 60° C. to 70° C.