CN111470992A - Clean process method for continuously synthesizing glycine - Google Patents
Clean process method for continuously synthesizing glycine Download PDFInfo
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- CN111470992A CN111470992A CN202010344605.8A CN202010344605A CN111470992A CN 111470992 A CN111470992 A CN 111470992A CN 202010344605 A CN202010344605 A CN 202010344605A CN 111470992 A CN111470992 A CN 111470992A
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- C07C227/00—Preparation of compounds containing amino and carboxyl groups bound to the same carbon skeleton
- C07C227/24—Preparation of compounds containing amino and carboxyl groups bound to the same carbon skeleton from hydantoins
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- C07C227/00—Preparation of compounds containing amino and carboxyl groups bound to the same carbon skeleton
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- C07D—HETEROCYCLIC COMPOUNDS
- C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
- C07D233/54—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members
- C07D233/66—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D233/72—Two oxygen atoms, e.g. hydantoin
- C07D233/74—Two oxygen atoms, e.g. hydantoin with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, attached to other ring members
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Abstract
A clean process method for continuously synthesizing glycine comprises the steps of preheating a carbon dioxide ammonia water solution prepared from an ammonia source, a carbon source and water, mixing the preheated ammonia water solution with hydroxyacetonitrile, continuously synthesizing, depressurizing and flashing, continuously hydrolyzing, gas stripping, concentrating, cooling and crystallizing, centrifuging for the first time, thermally dissolving and recrystallizing, centrifuging for the second time, and drying to obtain a glycine product; continuously separating partial carbon dioxide generated by hydrolysis in the hydrolysis reaction process; and the carbon dioxide and ammonia recovery system sequentially absorbs gas phase obtained by gas stripping, hydrolysis separation and decompression flash evaporation separation, and the obtained carbon dioxide ammonia water solution is recycled to the reaction system. The method improves the yield of the glycine by inhibiting the side reaction of the iminodiacetonitrile; through the reasonable arrangement of the timely release and recovery sequence of each gas phase in the system, the difficulty in recovering and reusing carbon dioxide and ammonia in the system is reduced, the loss of carbon dioxide and ammonia is reduced, the one-way conversion rate of hydrolysis is improved, the hydrolysis time is greatly shortened, and the method is an environment-friendly and clean process method for producing glycine.
Description
Technical Field
The invention relates to a clean process method for continuously synthesizing glycine by taking hydroxy acetonitrile as a raw material through a hydantoin method, belonging to the field of fine chemical intermediates.
Background
Glycine, also known as Glycine, is an amino acid with the simplest structure, has a chemical formula of C2H5NO2 and a molecular weight of 75.07, is an important intermediate for fine chemical engineering, and is widely applied to the fields of pesticides, medicines, foods, feeds, daily chemicals, organic synthesis and the like. China is the largest glycine production and consumption country in the world, and the market scale of glycine exceeds 35 million tons.
The conventional process for producing glycine in China is a chloroacetic acid ammonolysis method, but along with the enhancement of environmental awareness in recent years, the environmental protection problem brought by the chloroacetic acid ammonolysis method is increasingly prominent, and the process for producing glycine by taking hydroxyacetonitrile as a raw material is more and more emphasized. There are two routes for producing glycine by using hydroxy acetonitrile as raw material, one is hydroxy acetonitrile ammoniation method, and the other is hydantoin method. The hydroxyl acetonitrile ammonification method is characterized in that hydroxyl acetonitrile and ammonia are used as raw materials to carry out ammonification reaction in a water system to obtain amino acetonitrile, then the amino acetonitrile is subjected to alkaline hydrolysis and acidification to obtain glycine, products in the route contain iminodiacetic acid and inorganic salt, the purification and separation of the products are difficult, the product quality is poor, and the production cost is high. The hydantoin method is to synthesize glycine by hydroxyl acetonitrile, ammonia and carbon dioxide (or ammonium bicarbonate) in a water system at high temperature and high pressure.
The principle of synthesizing glycine by the hydantoin method is as follows:
the hydantoin method for preparing glycine is that glycolonitrile, a carbon source (such as carbon dioxide) and an ammonia source (such as ammonia) are firstly synthesized into intermediate products of hydantoin acid, hydantoin acid amide and the like in a water system, and then glycine is obtained through hydrolysis, and ammonia and carbon dioxide are released. Since ammonia and carbon dioxide can be recycled in the system, the hydantoin method is theoretically the cleanest glycine production process.
Many people in the art have studied continuous production of glycine by the hydantoin process.
Chinese patent CN103880690 discloses a clean production method of glycine, which separates the synthesis of hydantoin from the hydrolysis of hydantoin, and adopts gradient temperature rise for hydantoin synthesis, thereby reducing the decomposition of hydroxyacetonitrile to a certain extent, reducing the generation of by-products, and having higher conversion rate of raw materials. However, excessive ammonia and carbon dioxide in the system and ammonia and carbon dioxide released by hydrolysis are concentrated and recovered after the two-stage reaction is completed, so that the difficulty in recovering and reusing ammonia and carbon dioxide is increased, the hydrolysis reaction is not facilitated, and the single-pass yield of hydrolysis is low; in the raw material ratio, the amount of ammonia is larger than that of carbon dioxide, so that the side reaction of ammoniation of the hydroxy acetonitrile to generate the iminodiacetonitrile is obvious, and the yield and the purity of the glycine product are influenced. Chinese patents CN 201710969775.3 and CN 201910370199. X both propose that hydrolysis of hydantoin is realized by adopting a kettle-type series reactor, and also have the defects of long hydrolysis time, low single-pass yield of hydrolysis, difficult ammonia and carbon dioxide recovery and no good inhibition of side reaction of generating iminodiacetonitrile. After the first-step reaction, the CN 201710969775.3 firstly recovers carbon dioxide and ammonia through concentration processes such as rectification and the like, and then hydrolyzes, so that the recovery and the reuse of ammonia and carbon dioxide are not facilitated, and energy-saving concentration modes such as multi-effect concentration and the like cannot be adopted, so that the energy consumption is too high; the concentrated hydantoin synthesis solution is hydrolyzed, although the volume of a hydrolysis reactor can be reduced, the hydrolysis reaction time cannot be reduced because the hydantoin hydrolysis process continues to generate carbon dioxide and ammonia, and the single-pass yield of hydrolysis is low.
Chinese patent CN 201910948644.6 proposes that a multi-stage microchannel reactor is used to sequentially perform hydantoin synthesis and hydantoin hydrolysis reactions to achieve glycine production. Although the microchannel reactor can better realize the continuous synthesis of the glycine, the advantages of the microchannel reactor cannot be well exerted because the synthesis and hydrolysis of the hydantoin do not belong to the rapid reaction, and the defects of small capacity and poor corrosion resistance of the microchannel reactor cause that the device is difficult to amplify and operate durably and stably; ammonia and carbon dioxide in the system are recovered by gas stripping after the hydrolysis reaction is finished, so that the difficulty in applying is high; the single-pass yield of hydrolysis is low; the side reactions leading to iminodiacetonitrile are not well suppressed.
Chinese patent CN101148417 proposes that a system formed by connecting a tubular reactor and a multi-stage column bed reactor in series is used to realize continuous production of glycine, and the system directly returns the gas mainly containing carbon dioxide, which is decompressed and separated after the reaction and during the reaction, to recycle, although the carbon dioxide and ammonia in the system can be recovered and reused respectively to a certain extent, the carbon dioxide decompressed and separated still contains a certain amount of ammonia, and the carbon dioxide directly returns to reuse and needs to be pressurized by a compressor, and there is a problem that the compressor is blocked by the generated ammonium carbonate or ammonium bicarbonate during the pressurization; the method also has the problems of overlong hydrolysis time, low single-pass yield of hydrolysis and failure in well inhibiting the side reaction of generating iminodiacetonitrile.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a clean process method for continuously synthesizing glycine by a hydantoin method by using hydroxyacetonitrile as a raw material, in particular to a clean process method for inhibiting the occurrence of side reaction of iminodiacetonitrile by adjusting the proportion of ammonia and carbon dioxide, reducing the difficulty in recycling carbon dioxide and ammonia in a system, reducing the loss of carbon dioxide and ammonia, promoting the hydrolysis reaction, improving the single-pass yield of hydrolysis and shortening the time required by the hydrolysis reaction by timely releasing excessive carbon dioxide generated by hydrolysis and reasonably arranging the recovery sequence of each gas phase in the system.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
(1) carbon dioxide ammonia water solution prepared from an ammonia source, a carbon source and water and hydroxyacetonitrile aqueous solution enter a hydantoin reactor together for continuous reaction to obtain hydantoin synthetic solution, and reaction materials enter from the bottom of the hydantoin reactor and flow out from the upper part or the top of the hydantoin reactor;
(2) the liquid phase obtained after the hydantoin synthesis solution is subjected to pressure reduction flash evaporation separation enters a multi-stage series hydrolysis reactor for continuous hydrolysis, reaction materials enter from the bottom of each stage of the series hydrolysis reactor and flow out from the upper part or the top of each stage of the series hydrolysis reactor, and part of carbon dioxide generated by hydrolysis is continuously separated in the hydrolysis reaction process;
(3) and extracting or concentrating and steaming glycine-containing feed liquid from the final-stage hydrolysis reactor by using an air stripping tower to remove residual carbon dioxide and ammonia in the feed liquid, and refining the obtained liquid phase to obtain a glycine product.
According to the technical scheme, in the step (1), the ammonia source is ammonium bicarbonate, ammonium carbonate, liquid ammonia and/or ammonia water, and the carbon source is ammonium bicarbonate, ammonium carbonate and/or carbon dioxide.
Further, the carbon dioxide ammonia water solution in the step (1) is preheated by a preheater, mixed with the aqueous solution of hydroxyacetonitrile in a mixer according to the proportion, and then enters a hydantoin reactor for continuous reaction to obtain the hydantoin synthetic solution. The temperature of the carbon dioxide ammonia water solution preheated by the preheater is 55-100 ℃; the mixer is a static mixer, micromixer or other type of tubular mixer.
The technical scheme is that the hydantoin reactor in the step (1) is a tubular reactor, a column reactor, a tube bundle reactor or a combined reactor combining the column reactor and the tube bundle reactor.
The concentration of the hydroxy acetonitrile in the step (1) of the technical scheme is 15-65 wt%; the feeding molar ratio of the hydroxyl acetonitrile to the ammonia source, the carbon source and the water is as follows: carbon dioxide (or the total amount of carbon dioxide provided by the ammonia source together with the carbon source): ammonia (or total ammonia amount provided by the ammonia source together with the carbon source): water = 1: 1.6-22.5: 1.6-20: 10 to 80 parts.
Further, in the feeding molar ratio, the carbon dioxide (or the total carbon dioxide provided by the ammonia source and the carbon source) is: ammonia (or the total ammonia amount provided by the ammonia source and the carbon source) is more than or equal to 1.
Still further, in the feeding molar ratio, the carbon dioxide (or the total carbon dioxide provided by the ammonia source and the carbon source) is: ammonia (or the total amount of ammonia provided by the ammonia source together with the carbon source) > 1.
According to the technical scheme, the hydantoin synthetic solution is obtained through the continuous reaction in the step (1), the reaction pressure is 3.5-6.0 MPa, the reaction temperature is 60-160 ℃, and the reaction time is 0.3-2.0 h.
The technical scheme is that the hydantoin synthesis solution in the step (2) is subjected to pressure reduction flash evaporation separation, and the operating pressure is 0.2-3.5 MPa.
Further, the gas phase obtained by the pressure reduction flash evaporation separation of the hydantoin synthetic solution is recycled and reused.
The hydrolysis reactor in the step (2) of the technical scheme is a kettle type reactor, a column type reactor, a tube bundle type reactor or a combined type reactor combining the column type reactor and the tube bundle type reactor.
According to the technical scheme, in the hydrolysis reactor in the multistage series connection in the step (2), the number of the hydrolysis reactor is 2-15, preferably 3-9.
The technical scheme is that the step (2) of continuous hydrolysis is carried out, the reaction pressure is 0.5-5.5 MPa, and the reaction temperature is 120-180 ℃.
In the technical scheme, the step (2) of continuously separating partial carbon dioxide generated by hydrolysis in the hydrolysis reaction process means that gas-liquid separation is carried out at the top of one or more hydrolysis reactors, partial carbon dioxide released by hydrolysis enters a gas phase to be recycled and reused, and a liquid phase enters a next-stage hydrolysis reactor. The gas-liquid separation mode includes, but is not limited to, gas-liquid separation by arranging a gas-liquid separation space at the top of the hydrolysis reactor, and separation by connecting a separate gas-liquid separator in series after the outlet at the top of the hydrolysis reactor.
The technical scheme is that the stripping tower is extracted in the step (3), and the operating pressure of the stripping tower is normal pressure or negative pressure.
The concentration and the evaporation in the step (3) of the technical scheme are carried out, and the concentration operation pressure is normal pressure or negative pressure.
Further, the glycine-containing feed liquid is extracted by a stripping tower or is concentrated and evaporated to remove residual carbon dioxide and ammonia in the feed liquid, and the obtained gas phase is recycled and reused.
The liquid phase in the step (3) of the technical scheme is refined to obtain a glycine product, and the refining step is as follows: evaporating, concentrating, cooling, crystallizing, centrifuging for the first time, recrystallizing by hot melting, centrifuging for the second time, and drying; or the following steps: evaporating and concentrating, cooling and crystallizing, centrifuging for the first time, dissolving in heat, precipitating and crystallizing with alcohol, centrifuging for the second time, and drying.
Further, the evaporation concentration, the process water jacket obtained by condensing and recovering the evaporated water is used as an absorption liquid for recovering the separated gas phase, and the evaporation concentration adopts multiple-effect evaporation, including MVR multiple-effect evaporation. And (3) carrying out the first centrifugation, wherein the mother liquor obtained by centrifugal separation is subjected to hydrolysis reaction in the step (2). The hot dissolving refers to dissolving glycine obtained by first centrifugal separation by hot water. The recrystallization refers to cooling crystallization after hot melting. And the mother liquor after the second centrifugation and the centrifugal separation is subjected to evaporation concentration, thermosol or alcohol precipitation crystallization.
And further, decoloring the glycine subjected to hot melting by using an adsorbent, filtering adsorbent residues, and then performing subsequent crystallization treatment. The adsorbent is one or a combination of more of diatomite, a pure silicon microporous molecular sieve, natural zeolite or an artificially synthesized zeolite molecular sieve and active carbon. The activated carbon is powdered activated carbon, granular activated carbon, activated carbon fiber or a combination thereof. The adsorbent includes modified varieties of the adsorbents listed above.
Still further, the refining process may further include a second thermal melting recrystallization and a third centrifugation, or a second thermal melting, a second alcohol precipitation crystallization and a third centrifugation.
As mentioned above, the gas phase obtained by the reduced pressure flash evaporation separation of the hydantoin synthesis solution is recycled and reused, part of the carbon dioxide generated by continuous separation hydrolysis in the hydrolysis reaction process is recycled and reused, the glycine-containing feed liquid is extracted by a stripper or is concentrated and evaporated to remove the residual carbon dioxide and ammonia in the feed liquid to obtain the gas phase, and the gas phase is recycled and reused, and the method is characterized in that the gas phase is absorbed by water used by a carbon dioxide and ammonia recovery system or process water used for recycling and reusing to obtain a carbon dioxide ammonia water solution, and then the gas phase is returned to the step (1) for reuse; the carbon dioxide and ammonia recovery system absorbs the respective gas phases in the order: firstly, absorbing the gas phase containing carbon dioxide and ammonia extracted from a stripping tower or removed by concentration and evaporation, then absorbing the gas phase separated from gas and liquid in the hydrolysis reaction, and finally absorbing the gas phase separated by depressurizing and flash evaporating the hydantoin synthesis solution. When the two latter gas phases are absorbed, pressure absorption can be carried out as required.
The invention has the beneficial effects that:
1) by controlling the molar ratio of the hydantoin synthesis feed, the carbon dioxide (or the total carbon dioxide provided by the ammonia source and the carbon source) is: the ammonia (or the total ammonia amount provided by the ammonia source and the carbon source) is more than or equal to 1, the side reaction of the iminodiacetonitrile generated by ammoniating the hydroxyacetonitrile can be inhibited to the maximum extent, and the yield and the purity of the glycine product are ensured.
2) Through the pressure reduction flash separation of the hydantoin synthesis solution and the gas-liquid separation in the hydrolysis process, due to the solubility characteristics of carbon dioxide and ammonia in water, more carbon dioxide is released and separated out firstly, enters a gas phase and is separated out, the concentration of ammonium ions in the feed liquid is further higher than that of carbonate ions, the pH value of the feed liquid shifts towards alkalinity, the enhancement of the alkalinity of a reaction system is favorable for promoting the reaction of hydantoin hydrolysis to generate glycine, and the hydrolysis reaction time is greatly shortened; through the pressure reduction flash separation of the hydantoin synthesis solution and the gas-liquid separation in the hydrolysis process, carbon dioxide in molecular form in the feed liquid is released, the reaction balance of the hydantoin hydrolysis for generating glycine and releasing carbon dioxide and ammonia is favorably shifted to the right, and the one-way conversion rate of the hydantoin hydrolysis is improved.
3) The flow pattern that the reaction materials adopted in the step (1) and the step (2) enter from the bottom and flow out from the upper part or the top of the hydantoin reactor or the hydrolysis reactor is beneficial to gathering surplus or generated carbon dioxide in the system at the upper part or the top of the reactor, so that the separation of the carbon dioxide is facilitated.
4) In the pressure reduction flash separation of the hydantoin synthesis solution and the gas-liquid separation in the hydrolysis reaction process, more carbon dioxide is separated out firstly, so that the ammonia content in the gas phase extracted or concentrated and evaporated from the stripping tower is far higher than the carbon dioxide content. The ammonia and the carbon dioxide in the reaction system can be recovered and reused conveniently, and the loss of the ammonia and the carbon dioxide can be avoided. The gas phase extracted from the gas tower or removed by concentration and evaporation can be absorbed under normal pressure; the proper separation pressure is selected during the gas-liquid separation of the hydrolysis reaction and the depressurization flash separation of the hydantoin synthesis solution, and the pressurization absorption of the hydrolysis reaction and the hydantoin synthesis solution can be realized without arranging a pressurization device, thereby saving energy.
5) The invention can realize zero discharge of waste water and waste liquid and avoid the loss of ammonia and carbon dioxide in a gas phase system, thereby being an environment-friendly and clean process method for producing the glycine.
Drawings
FIG. 1 is a schematic process flow diagram of the present invention.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The present invention is illustrated below by way of examples, but the present invention is not limited to these examples.
Example 1: ammonia, carbon dioxide and water in a ratio of 1: 1: preparing a carbon dioxide ammonia water solution according to the molar ratio of 12, preheating the feed flow rate of 390kg/h to 80 ℃ through a preheater, rapidly mixing the feed flow rate of 390kg/h with 44wt% hydroxyl acetonitrile solution with the feed flow rate of 63.5kg/h in a static mixer, entering a column reactor from the bottom, reacting for 45min at the pressure of 5.5MPa and the temperature of 110 ℃ to obtain a hydantoin synthetic solution, and then flowing out of the top of the reactor to enter a depressurization flash evaporator; the operating pressure of the flash evaporator is 1.5MPa, the gas phase subjected to flash evaporation separation is subjected to carbon dioxide and ammonia recovery system, the liquid phase enters a 3-stage series column reactor for continuous hydrolysis, and the material of each stage of reactor enters from the bottom and flows out from the top; the operating pressure of the hydrolysis reactor is 3.5MPa, the temperature is 160 ℃, the material flowing out of the top of each stage of hydrolysis reactor enters a gas-liquid separator to continuously separate part of the generated carbon dioxide into a carbon dioxide and ammonia recovery system, and the liquid phase enters the next stage of hydrolysis reactor; the feed liquid from the final stage hydrolysis reactor enters a gas stripping tower to extract residual ammonia and carbon dioxide in the feed liquid, the feed liquid enters a gas phase carbon dioxide removing and ammonia recovering system, the liquid phase is subjected to triple effect evaporation concentration, cooling crystallization, first centrifugation, water adding hot dissolution, activated carbon adding decoloration, activated carbon residue filtering, cooling recrystallization, second centrifugation and drying to obtain a glycine product, and the purity of the glycine product is 99.2% through analysis. Mother liquor obtained by the first centrifugation and the second centrifugation is returned for reuse.
In a carbon dioxide and ammonia recovery system, water or process water used for triple-effect evaporation, concentration, condensation, recovery and reuse firstly absorbs gas phase extracted from a stripper, then absorbs gas phase continuously separated by a hydrolysis reactor, and finally absorbs gas phase separated by depressurization, flash evaporation and separation of a hydantoin synthesis solution, and the obtained carbon dioxide ammonia water solution is used before a preheater.
In this example, the liquid phase material at the bottom of the flash evaporator was sampled and analyzed, and the formation of a trace amount of iminodiacetonitrile was detected, and this side reaction was suppressed to a certain extent as compared with example 1. Sampling, analyzing the discharge of the final stage hydrolysis reactor before the centrifugal mother liquor is reused, and calculating the conversion per pass of the hydantoin hydrolysis to generate the glycine to be 86.1 percent.
Example 2: ammonia, carbon dioxide and water in a ratio of 1: 1.15: 15, preheating the feed flow rate of 4200kg/h to 80 ℃ through a preheater, rapidly mixing the feed flow rate of 4200kg/h with a hydroxyacetonitrile solution with the concentration of 40wt% and the feed flow rate of 590kg/h in a static mixer, allowing the mixture to enter a tube bundle type reactor from the bottom, reacting for 35min at the temperature of 120 ℃ under the pressure of 4.5MPa, and allowing the mixture to flow out of the top of the reactor and enter a pressure reduction flash evaporator; the operating pressure of the flash evaporator is 1.0MPa, the gas phase subjected to flash evaporation separation is subjected to carbon dioxide removal and ammonia recovery, the liquid phase enters a 5-stage series-connected column reactor and a composite reactor combined with a tube bundle reactor for continuous hydrolysis, and the material of each stage of reactor enters from the bottom and flows out from the upper part; the operating pressure of the hydrolysis reactor is 2.5MPa, the temperature is 150 ℃, the top of each stage of hydrolysis reactor is provided with a gas-liquid separation space for separating part of generated carbon dioxide to remove a carbon dioxide and ammonia recovery system, and the liquid phase enters the next stage of hydrolysis reactor; the feed liquid from the final stage hydrolysis reactor enters a negative pressure evaporation system to evaporate residual ammonia and carbon dioxide in the feed liquid, the feed liquid enters a gas phase carbon dioxide removal and ammonia recovery system, the liquid phase is subjected to triple effect evaporation concentration, cooling crystallization, first centrifugation, water adding hot dissolution, activated carbon adding decoloration, activated carbon residue filtering, cooling recrystallization, second centrifugation and drying to obtain a glycine product, and the purity of the glycine product is 99.8% through analysis. Mother liquor obtained by the first centrifugation and the second centrifugation is returned for reuse.
In a carbon dioxide and ammonia recovery system, water or process water used for triple-effect evaporation, concentration, condensation, recovery and reuse firstly absorbs the gas phase evaporated by a negative pressure evaporation and desorption system, then absorbs the gas phase continuously separated by a hydrolysis reactor, and finally absorbs the gas phase separated by the reduced pressure flash evaporation of a hydantoin synthesis solution, and the obtained carbon dioxide ammonia water solution is sleeved in front of a preheater.
In this example, the liquid phase material at the bottom of the flash evaporator was sampled and analyzed, and the formation of iminodiacetonitrile was not detected, and this side reaction was well suppressed. Sampling, analyzing the discharge of the final stage hydrolysis reactor before the centrifugal mother liquor is reused, and calculating the conversion per pass of the hydantoin hydrolysis to generate the glycine to be 88.2 percent.
Example 3: ammonia, carbon dioxide and water in a ratio of 1: 1.2: 15, preheating a feed flow of 4250kg/h to 90 ℃ through a preheater, rapidly mixing the feed flow of 4250kg/h with a 38wt% hydroxyacetonitrile solution with the feed flow of 670kg/h in a static mixer, allowing the mixture to enter a column reactor from the bottom, reacting for 60min at the pressure of 4.0MPa and the temperature of 100 ℃, and allowing the mixture to flow out of the top of the reactor and enter a pressure reduction flash evaporator; the operating pressure of the flash evaporator is 2.2MPa, the gas phase subjected to flash evaporation separation is subjected to carbon dioxide removal and ammonia recovery, the liquid phase enters a composite reactor combined with a 6-stage series column reactor and a tube bundle reactor for continuous hydrolysis, and the material of each stage of reactor enters from the bottom and flows out from the upper part; the operating pressure of the hydrolysis reactor is 3.8MPa, the temperature is 140 ℃, the top of each stage of hydrolysis reactor is provided with a gas-liquid separation space for separating part of generated carbon dioxide to remove a carbon dioxide and ammonia recovery system, and the liquid phase enters the next stage of hydrolysis reactor; the feed liquid from the final stage hydrolysis reactor enters a normal pressure steaming and dehydrating system to distill out residual ammonia and carbon dioxide in the feed liquid, the residual ammonia and carbon dioxide enter a gas phase carbon dioxide removing and ammonia recovering system, the liquid phase is subjected to triple effect evaporation concentration, cooling crystallization, first centrifugation, water adding hot dissolution, activated carbon adding decoloration, activated carbon residue filtering, alcohol precipitation recrystallization, second centrifugation and drying to obtain a glycine product, and the purity of the glycine product is 99.9% after analysis. Mother liquor obtained by the first centrifugation and the second centrifugation is returned for reuse.
In a carbon dioxide and ammonia recovery system, the vapor phase evaporated by a normal pressure evaporation and dehydration system is firstly absorbed by water or process water used for triple effect evaporation, concentration, condensation, recovery and reuse, the vapor phase continuously separated by a hydrolysis reactor is then absorbed, the vapor phase separated by the reduced pressure flash evaporation of a hydantoin synthesis solution is finally absorbed, and the obtained carbon dioxide ammonia water solution is sleeved in front of a preheater.
In this example, the liquid phase material at the bottom of the flash evaporator was sampled and analyzed, and the formation of iminodiacetonitrile was not detected, and this side reaction was well suppressed. Sampling, analyzing the discharge of the final stage hydrolysis reactor before the centrifugal mother liquor is reused, and calculating the one-way conversion rate of the hydantoin hydrolysis to generate the glycine to be 87.4 percent.
Comparative example 1: ammonia, carbon dioxide and water in a ratio of 1.2: 1: preparing a carbon dioxide ammonia water solution according to the molar ratio of 12, preheating the feed flow of 400kg/h to 85 ℃ through a preheater, rapidly mixing the feed flow of 400kg/h with 44wt% hydroxyl acetonitrile solution with the feed flow of 63.5kg/h in a static mixer, entering a tubular reactor from the bottom, reacting for 50min at the pressure of 5.0MPa and the temperature of 115 ℃ to obtain a hydantoin synthetic solution, and then flowing out of the top of the reactor and entering a depressurization flash evaporator; the operating pressure of the flash evaporator is 2.0MPa, the gas phase subjected to flash evaporation separation is subjected to carbon dioxide and ammonia recovery system, the liquid phase enters a 3-stage series column reactor for continuous hydrolysis, and the material of each stage of reactor enters from the bottom and flows out from the top; the operating pressure of the hydrolysis reactor is 3.2MPa, the temperature is 145 ℃, the feed liquid from the last stage hydrolysis reactor enters a stripping tower to extract ammonia and carbon dioxide in the feed liquid, the ammonia and the carbon dioxide enter a gas phase carbon dioxide and ammonia removing recovery system, the liquid phase is subjected to triple effect evaporation concentration, cooling crystallization, primary centrifugation, water adding hot melting, activated carbon adding decoloration and activated carbon residue filtering, cooling recrystallization, secondary centrifugation and drying to obtain a glycine product, and the purity of the glycine product is 98.6% after analysis.
In a carbon dioxide and ammonia recovery system, water or process water used for triple-effect evaporation, concentration, condensation, recovery and reuse firstly absorbs gas phase extracted from a stripper, and then absorbs gas phase separated by depressurization, flash evaporation and separation of a hydantoin synthesis solution, and the obtained carbon dioxide ammonia water solution is sleeved in front of a preheater.
In this comparative example, a sample was taken from the bottom liquid phase of the flash evaporator, and a small amount of iminodiacetonitrile was detected. Sampling, analyzing the discharge of the final stage hydrolysis reactor before the centrifugal mother liquor is reused, and calculating the conversion per pass of the hydantoin hydrolysis to generate the glycine to be 68.5 percent.
Claims (10)
1. A clean process method for continuously synthesizing glycine is characterized by comprising the following steps:
(1) carbon dioxide ammonia water solution prepared from an ammonia source, a carbon source and water and hydroxyacetonitrile aqueous solution enter a hydantoin reactor together for continuous reaction to obtain hydantoin synthetic solution, and reaction materials enter from the bottom of the hydantoin reactor and flow out from the upper part or the top of the hydantoin reactor; the ammonia source is ammonium bicarbonate, ammonium carbonate, liquid ammonia and/or ammonia water, and the carbon source is ammonium bicarbonate, ammonium carbonate and/or carbon dioxide;
(2) the liquid phase obtained after the hydantoin synthesis solution is subjected to pressure reduction flash evaporation separation enters a multi-stage series hydrolysis reactor for continuous hydrolysis, reaction materials enter from the bottom of each stage of the series hydrolysis reactor and flow out from the upper part or the top of each stage of the series hydrolysis reactor, and part of carbon dioxide generated by hydrolysis is continuously separated in the hydrolysis reaction process;
(3) and extracting or concentrating and steaming glycine-containing feed liquid from the final-stage hydrolysis reactor by using an air stripping tower to remove residual carbon dioxide and ammonia in the feed liquid, and refining the obtained liquid phase to obtain a glycine product.
2. The clean process method for continuously synthesizing the glycine as claimed in claim 1, wherein the carbon dioxide ammonia aqueous solution in the step (1) is preheated by a preheater, mixed with the hydroxyacetonitrile aqueous solution in a mixer according to the mixture ratio, and then enters the hydantoin reactor for continuous reaction to obtain the hydantoin synthesis solution; the temperature of the carbon dioxide ammonia water solution preheated by the preheater is 55-100 ℃; the mixer is a static mixer, micromixer or other type of tubular mixer.
3. The clean process method for continuously synthesizing the glycine as claimed in claim 1, wherein the concentration of the hydroxyacetonitrile in the step (1) is 15wt% -65 wt%; the feeding molar ratio of the hydroxyl acetonitrile to the ammonia source, the carbon source and the water is as follows: carbon dioxide (or the total amount of carbon dioxide provided by the ammonia source together with the carbon source): ammonia (or total ammonia amount provided by the ammonia source together with the carbon source): water = 1: 1.6-22.5: 1.6-20: 10 to 80 parts.
4. The feed molar ratio of claim 3, wherein the molar ratio of carbon dioxide (or the total amount of carbon dioxide provided by the ammonia source and the carbon source): ammonia (or the total ammonia amount provided by the ammonia source and the carbon source) is more than or equal to 1.
5. The clean process method for continuously synthesizing glycine as claimed in claim 1, wherein the step (1) of continuously reacting to obtain the hydantoin synthesis solution has a reaction pressure of 3.5-6.0 MPa, a reaction temperature of 60-160 ℃ and a reaction time of 0.3-2.0 h.
6. The clean process method for continuously synthesizing the glycine as claimed in claim 1, wherein the operation pressure of the pressure-reducing flash separation in the step (2) is 0.2-3.5 MPa, and the gas phase obtained by the pressure-reducing flash separation is recycled and reused.
7. The clean process method for continuously synthesizing glycine as claimed in claim 1, wherein the continuous hydrolysis in step (2) is carried out under the reaction pressure of 0.5-5.5 MPa and the reaction temperature of 120-180 ℃.
8. The clean process method for continuously synthesizing glycine as claimed in claim 1, wherein the hydantoin reactor is a tubular reactor, a column reactor, a tube bundle reactor or a combined reactor of a column reactor and a tube bundle reactor; the hydrolysis reactor is a kettle type reactor, a column type reactor, a tube bundle type reactor or a combined type reactor combining the column type reactor and the tube bundle type reactor.
9. The clean process method for continuously synthesizing glycine as claimed in claim 1, wherein the step (2) of continuously separating partial carbon dioxide generated by hydrolysis in the hydrolysis reaction process means that gas-liquid separation is performed at the top of one or more hydrolysis reactors, partial carbon dioxide released by hydrolysis enters a gas phase for recycling and reusing, and a liquid phase enters the next stage hydrolysis reactor; the gas-liquid separation mode includes, but is not limited to, gas-liquid separation by arranging a gas-liquid separation space at the top of the hydrolysis reactor, and separation by connecting a separate gas-liquid separator in series after the outlet at the top of the hydrolysis reactor.
10. The clean process method for continuously synthesizing the glycine as claimed in the claims 1, 6 and 9, which is characterized in that the gas phase obtained by the pressure reduction flash evaporation separation of the hydantoin synthesis solution, the gas phase obtained by the gas-liquid separation of the hydrolysis reaction, the gas phase obtained by extracting or concentrating and evaporating the glycine-containing feed liquid by a stripping tower to remove the residual carbon dioxide and ammonia in the feed liquid, the gas phases are absorbed by water or process water recycled and reused in a carbon dioxide and ammonia recovery system to obtain a carbon dioxide ammonia water solution, and then the carbon dioxide ammonia water solution is returned to the step (1) for reuse; the carbon dioxide and ammonia recovery system absorbs the respective gas phases in the order: firstly, absorbing the gas phase containing carbon dioxide and ammonia extracted from a stripping tower or removed by concentration and evaporation, then absorbing the gas phase separated from gas and liquid in the hydrolysis reaction, and finally absorbing the gas phase separated by depressurizing and flash evaporating the hydantoin synthesis solution.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112552197A (en) * | 2020-12-17 | 2021-03-26 | 华阳新材料科技集团有限公司 | Kettle type continuous glycine production method |
| CN113045441A (en) * | 2021-03-22 | 2021-06-29 | 铂尊投资集团有限公司 | Method for producing feed and food-grade glycine and device for implementing method |
| CN114524738A (en) * | 2022-02-22 | 2022-05-24 | 天宝动物营养科技股份有限公司 | Glycine preparation method for reducing iminodiacetic acid content |
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2020
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112552197A (en) * | 2020-12-17 | 2021-03-26 | 华阳新材料科技集团有限公司 | Kettle type continuous glycine production method |
| CN112552197B (en) * | 2020-12-17 | 2023-07-28 | 华阳新材料科技集团有限公司 | Kettle type continuous glycine production method |
| CN113045441A (en) * | 2021-03-22 | 2021-06-29 | 铂尊投资集团有限公司 | Method for producing feed and food-grade glycine and device for implementing method |
| CN114524738A (en) * | 2022-02-22 | 2022-05-24 | 天宝动物营养科技股份有限公司 | Glycine preparation method for reducing iminodiacetic acid content |
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