1. The utility model provides a hydroxyl acetonitrile ammoniation reaction unit which characterized in that includes:

a premixing unit for receiving and mixing reaction raw materials; the pre-mixing unit comprises a micro-scale pre-mixer;

the multistage reaction unit is arranged at the downstream of the premixing unit and used for receiving the mixed reaction raw materials; the multistage reaction unit comprises multistage reactors which are sequentially connected in series, and the reaction temperature in the multistage reactors is controlled to be gradually increased; and controlling the reaction temperature in the primary reactor to be greater than the mixing temperature in the premixing unit.

2. The hydroxyacetonitrile amination apparatus according to claim 1, wherein:

the micro-scale premixer comprises a fluid distributor and a fluid homogenizer; the fluid distributor penetrates through the front end of the fluid homogenizer along the fluid flowing direction and is communicated with the fluid homogenizer.

3. The hydroxyacetonitrile amination apparatus according to claim 2, wherein:

a plurality of distribution holes are formed in the side wall of the fluid distributor, which is in compliance with the fluid flowing direction, and the distribution holes are communicated with the fluid homogenizing mixer; the fluid homogenizer comprises a plurality of rotational flow mixing units, and any rotational flow mixing unit adopts a positive rotation unit or a differential rotation unit.

4. The hydroxyacetonitrile amination apparatus according to claim 3, wherein:

the positive rotation units and the negative rotation units in the fluid homomixer are arranged in a crossed manner;

and/or the presence of a gas in the gas,

the length h of any one swirl mixing unit is 0.5-2 times of the diameter D of the fluid homogenizer, and the torsion angle is 160-180 degrees.

5. The hydroxyacetonitrile amination apparatus according to claim 3, wherein:

the distribution holes are distributed on the side surface of the fluid distributor facing the fluid flowing direction and are positioned in the arc length corresponding to the central included angle not more than alpha, and the interface included angle alpha is 90-160 degrees;

and/or the aperture of the distribution holes is 1-10 mm, the distribution holes are arranged in a regular triangle, and the distance between the distribution holes is 1.5-2 times of the aperture of the distribution holes;

and/or the distance B between the distribution holes and the adjacent rotational flow mixing units is 0.5-2 times of the diameter of the fluid homogenizer.

6. The hydroxyacetonitrile amination apparatus according to claim 1, wherein:

the multistage reaction unit is a tubular reactor which is connected in series in a multistage manner, and the diameter of a reaction tube in the tubular reactor is 5-50 mm;

and/or the presence of a gas in the gas,

the reactors are arranged in 2-5 stages in series;

and/or the presence of a gas in the gas,

the premixing unit and any stage of reaction unit are respectively provided with a temperature detector and a heat exchange medium automatic control valve, and the device is also provided with an automatic control system which is electrically connected with the temperature detector and the heat exchange medium automatic control valve and is used for controlling the reaction temperature in the premixing unit and each reaction unit.

7. A hydroxyl acetonitrile ammoniation reaction process is characterized by comprising the following steps:

s1, uniformly mixing the hydroxyacetonitrile and the ammonia water in a micro-scale premixer in the premixing unit;

and S2, gradually feeding the uniformly mixed mixture of the hydroxyacetonitrile and the ammonia water into a multistage reactor, wherein the reaction temperature in the first stage reactor is controlled to be higher than the mixing temperature in the premixing unit, and the reaction temperature in the multistage reactor is controlled to be gradually increased.

8. The hydroxyacetonitrile amination process according to claim 7, characterized in that:

in step S1, the excess ammonia water is added into the fluid homogenizer in the micro-scale premixer, the hydroxyacetonitrile enters the fluid distributor in the micro-scale premixer, is distributed into the ammonia water at a high speed along the fluid flow direction in the fluid homogenizer through the distribution holes, forms uniform shearing and rapid mixing for the ammonia water, and is subjected to shear mixing of normal rotation and abnormal rotation in the rotational flow mixing unit to achieve uniform mixing of the hydroxyacetonitrile and the ammonia water.

9. The hydroxyacetonitrile amination process according to claim 7, characterized in that:

in step S1, the mixing temperature in the premixing unit is controlled within 5-15 ℃, the pressure is controlled within 0.1-1.5MPa, and the retention time is 1-2S.

10. The hydroxyacetonitrile amination process according to claim 7, characterized in that:

in the step S2, the uniformly mixed mixture of the hydroxy acetonitrile and the ammonia water enters a primary reactor, wherein the temperature in the primary reactor is controlled to be 20-50 ℃, and the retention time is 3-10S; controlling the temperature in the second-stage tubular reactor to be 40-60 ℃ and the retention time to be 2-4 mins; and controlling the temperature in the third-stage tubular reactor to be 50-70 ℃ and the retention time to be 2-4 mins.

Background

Glycine, also known as glycine or glycine, is the simplest compound in amino acid group, is an important organic synthetic intermediate, and is widely applied to industries such as medicine, food, pesticide, feed and the like.

The traditional glycine synthesis adopts a chloroacetic acid ammonolysis process, but has the defects of difficult removal of byproducts such as ammonium chloride and the like, poor product quality and high refining cost; the urotropine as the catalyst can not be recovered, and the reaction time is long. In order to improve the yield of the glycine, improve the purity of the product, reduce the cost and overcome the defect of poor quality of the product by the chloroacetic acid method. In recent years, a process technology for synthesizing glycine by using hydroxy acetonitrile as a raw material has been researched.

The process route of taking the hydroxyl acetonitrile as the raw material has two kinds, one is that the hydroxyl acetonitrile reacts with ammonia to produce the aminoacetonitrile, the aminoacetonitrile is alkaline hydrolyzed to produce the sodium glycinate, and the sodium glycinate reacts with acid to produce the glycine, and the process route is called the hydroxyl acetonitrile method for short. The other is the method for producing hydantoin by reacting hydroxyl acetonitrile with ammonium bicarbonate and producing glycine by hydrolyzing hydantoin, which is called direct hydantoin method for short.

The main reaction principle of the hydantoin method is shown in fig. 5:

the route is realized at high temperature and high pressure, and the nitrile, ammonia and intermediate have high reactivity, so that the number of byproducts is large and the mechanism is complex. These by-products are mostly produced in the reaction process from hydroxyacetonitrile to hydantoin. The by-product of hydantoin hydrolysis is mainly hydantoin acid.

The process has more main byproducts, and the byproducts with more contents in the composition can be analyzed to be as follows: hydrocyanic acid and ammonia, methylamino acetic acid reacts with ammonia to produce glycine dipeptide, glycine tripeptide, hydantoin acid amide, 2, 5-diketopiperazine, incompletely reacted methylamino acetic acid, glycine ammonia and other intermediate products, hydantoin incompletely hydrolyzed product hydantoin acid and the like.

The process was studied in japan at the earliest of the 80 s and the 90 s, but the process has not been industrialized worldwide since it has many by-products and is difficult to separate.

The technical route of the hydroxy acetonitrile method is as follows:

the reaction principle of the hydroxy acetonitrile method comprises two steps: (1) ammoniating the hydroxyacetonitrile to produce an intermediate aminoacetonitrile; (2) producing sodium glycinate by alkaline hydrolysis of aminoacetonitrile, and producing glycine by acidifying sodium glycinate.

Chinese patent document CN201110351893.0 is representative of glycine synthesized by hydroxyacetonitrile, and proposes a process for producing aminoacetonitrile by ammonification of hydroxyacetonitrile and ammonia, producing sodium glycinate by alkaline hydrolysis of aminoacetonitrile, and producing glycine by reacting sodium glycinate with sulfuric acid. The glycine synthesis method is characterized in that glycine is synthesized through the steps of ammoniation, alkaline hydrolysis, ammonia discharge acidification, decoloration, concentration desalination crystallization and recrystallization, wherein the reaction of ammoniation of aminoacetonitrile with ammonia water is carried out in a single-tube reactor, the ammoniation reactor is controlled by integrated temperature and pressure, the reaction temperature is 50-100 ℃, the reaction pressure is 0.5-2.0 MPa, and the reaction time is 4-10 minutes.

Although the process avoids the defects of difficult removal of byproducts such as ammonium chloride and the like and poor product quality in the traditional chloroacetic acid method glycine synthesis process, the process has the following problems: 1) the patent scheme is a laboratory lab technical scheme, the amination reaction in the patent is completed in a single-tube reactor, the heat transfer difficulty does not exist, but for industrial devices, the large single-tube reactor is equivalent to an adiabatic reactor, and the moving of reaction heat is not facilitated. The uneven temperature field can cause the local over-temperature of the middle part in the reactor, so that the side reaction is increased, the yield of the aminoacetonitrile is reduced, and the yield of the final product glycine is reduced; 2) the hydroxyl acetonitrile and ammonia adopt a single reaction condition control mode, which can cause large production probability of dark color oligomer and more consumption of later-stage decolorization activated carbon. 3) The pure hydroxyacetonitrile adopted in the embodiment reacts with the ammonia water, and the pure hydroxyacetonitrile can spontaneously polymerize at the temperature of more than 20 ℃, so that the mixed reaction of the hydroxyacetonitrile and the ammonia water cannot be realized, and the safety risk is high. 4) The industrial device based on the patent has the highest practical yield of the glycine of about 70 percent.

Based on this, the technical personnel in the field need to provide a hydroxyacetonitrile ammonification reaction device and a process which are suitable for industrial production and can reduce the formation probability of colored groups and byproducts in the ammonification reaction, thereby reducing the decoloring and separating cost.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the hydroxyl acetonitrile ammonification reaction device and the process, which are suitable for industrial production and can reduce the formation probability of colored groups and byproducts in the ammonification reaction so as to reduce the decoloring and separating cost.

One of the purposes of the invention is to provide a hydroxyl acetonitrile ammoniation reaction device, which adopts the following technical scheme:

a hydroxyl acetonitrile ammoniation reaction device comprises:

a premixing unit for receiving and mixing reaction raw materials; the pre-mixing unit comprises a micro-scale pre-mixer;

the multistage reaction unit is arranged at the downstream of the premixing unit and used for receiving the mixed reaction raw materials; the multistage reaction unit comprises multistage reactors which are sequentially connected in series, and the reaction temperature in the multistage reactors is controlled to be gradually increased; and controlling the reaction temperature in the primary reactor to be greater than the mixing temperature in the premixing unit.

Preferably, the micro-scale premixer comprises a fluid distributor and a fluid homogenizer; the fluid distributor penetrates through the front end of the fluid homogenizer along the fluid flowing direction and is communicated with the fluid homogenizer.

Furthermore, a plurality of distribution holes are formed in the side wall of the fluid distributor, which is in compliance with the fluid flowing direction, and the distribution holes are communicated with the fluid homogenizing and mixing device; the fluid homogenizer comprises a plurality of rotational flow mixing units, and any rotational flow mixing unit adopts a positive rotation unit or a differential rotation unit.

Further, the normal rotation unit and the abnormal rotation unit in the fluid homomixer are arranged in a crossed mode.

Furthermore, the length h of any one of the rotational flow mixing units is 0.5-2 times of the diameter D of the fluid homogenizer, and the torsion angle is 160-180 degrees.

Further, the distribution holes are distributed on the side surface of the fluid distributor facing the fluid flowing direction and located in the arc length corresponding to the central included angle not more than α (as shown in fig. 3), and the interface included angle α is 90 ° to 160 °.

Furthermore, the aperture of the distribution holes is 1-10 mm, the distribution holes are arranged in a regular triangle, and the distance between the distribution holes is 1.5-2 times of the aperture of the distribution holes.

Further, the distance B between the distribution holes and the adjacent rotational flow mixing units is 0.5-2 times of the diameter of the fluid homogenizer.

Preferably, the multistage reaction unit is a tubular reactor with a plurality of stages connected in series.

Preferably, the reactors are 2-5 stages connected in series.

Preferably, the premixing unit and any stage of reaction unit are respectively provided with a temperature detector and a heat exchange medium automatic control valve, and the device is also provided with an automatic control system which is electrically connected with the temperature detector and the heat exchange medium automatic control valve and is used for controlling the reaction temperature in the premixing unit and each reaction unit.

The automatic control system can be a DNS control system, and can also be other systems such as a PLC control system and the like.

Furthermore, the diameter of the reaction tube in the tubular reactor is 5-50 mm.

Further, the temperature in the micro-scale premixer is controlled to be 5-15 ℃, the pressure is controlled to be within the range of 0.1-1.5MPa, and the retention time is 1-2 s.

Further, the multi-stage reaction unit is provided with 3 stages of reactors connected in series; controlling the temperature in the first-stage reactor to be 20-50 ℃ and the retention time to be 3-10 s; controlling the temperature in the secondary reactor to be 40-60 ℃ and the retention time to be 2-4 mins; controlling the temperature in the three-stage reactor to be 50-70 ℃ and the retention time to be 2-4 mins.

The invention also aims to provide a hydroxy acetonitrile ammoniation reaction process, which comprises the following steps:

s1, uniformly mixing the hydroxyacetonitrile and the ammonia water in a micro-scale premixer in the premixing unit;

and S2, gradually feeding the uniformly mixed mixture of the hydroxyacetonitrile and the ammonia water into a multistage reactor, wherein the reaction temperature in the first stage reactor is controlled to be higher than the mixing temperature in the premixing unit, and the reaction temperature in the multistage reactor is controlled to be gradually increased.

Preferably, in step S1, the excessive ammonia water is added into the fluid homogenizer in the micro-scale premixer, the hydroxyacetonitrile enters the fluid distributor in the micro-scale premixer, is distributed into the ammonia water at a high speed in the fluid flowing direction of the fluid homogenizer through the distribution holes, so as to form uniform shearing and rapid mixing for the ammonia water, and is subjected to shear mixing of normal rotation and iso-rotation in the rotational flow mixing unit, so as to achieve uniform mixing of the hydroxyacetonitrile and the ammonia water.

Preferably, in step S1, the mixing temperature in the premixing unit is controlled within the range of 5 to 15 ℃, the pressure is controlled within the range of 0.1 to 1.5MPa, and the residence time is controlled within the range of 1S to 2S.

Preferably, in the step S2, the uniformly mixed mixture of the hydroxyacetonitrile and the ammonia water enters a first-stage reactor, wherein the temperature in the first-stage reactor is controlled to be 20-50 ℃, and the retention time is 3-10S; controlling the temperature in the second-stage tubular reactor to be 40-60 ℃ and the retention time to be 2-4 mins; and controlling the temperature in the third-stage tubular reactor to be 50-70 ℃ and the retention time to be 2-4 mins.

Compared with the prior art, the invention can bring the following beneficial effects:

1) according to the invention, by researching the reaction mechanism of the hydroxyl acetonitrile and the ammonia, as the activity of the two reaction monomers of the hydroxyl acetonitrile and the ammonia is very high, the initial reaction speed is high, and the temperature is controlled within a proper range, the low yield and the deep chromaticity are avoided; in the latter half of the reaction, the reaction rate is accelerated by appropriately increasing the temperature range, because the reaction rate is lowered. Thereby avoiding excessive polymerization of materials and formation of colored group byproducts in the reaction process.

2) The method adopts a premixer with a special structure to uniformly mix the hydroxyacetonitrile and the ammonia water at a low temperature (outside the temperature range of the reactor) by low-temperature premixing, so that the nonuniform coefficient of the mixture is less than 0.05 percent, and the byproducts such as colored polymers and the like generated by the self-polymerization of the hydroxyacetonitrile due to the nonuniform reaction in the mixing process are avoided.

3) Compared with a single-tube reactor, the tubular reactor adopted by the invention not only improves the heat transfer efficiency and can more accurately control the reaction temperature, but also can better keep the piston flow and eliminate the amplification effect compared with the single-tube reactor, thereby being more suitable for the industrial amplification production of the hydroxyacetonitrile ammoniation reaction.

4) The invention adopts the multistage series reaction of differential temperature control to replace the first-stage temperature control mode of a single reactor, and the reaction temperature in the first-stage reactor is reduced to ensure that the initial reaction stage is below 50 ℃, thereby effectively controlling the generation probability of iminodiacetonitrile and nitrilotriacetonitrile, properly improving the reaction temperature of the second-stage reactor and the third-stage reactor and improving the reaction rate of the tail reaction.

Drawings

FIG. 1 is a schematic structural diagram of a hydroxyacetonitrile amination reaction device.

FIG. 2 is an enlarged view of the construction of the micro-scale premixer of FIG. 1.

Fig. 3 is a schematic diagram of the distribution of distribution holes on a fluid distributor.

Fig. 4 is a cross-sectional view of an included angle of an interface formed by distribution holes of a fluid distributor.

FIG. 5 is a schematic diagram of the main reaction of the hydantoin process.

The notations in the figures have the following meanings:

1-a pre-mixing unit; 10-fluid distributor, 100-distribution holes; 11-fluid homomixer, 111-normal rotation unit, 112-abnormal rotation unit;

2-a first-stage reactor, 3-a second-stage reactor and 4-a third-stage reactor.

Detailed Description

The technical solution of the present invention will be clearly and completely described below with reference to the specific embodiments. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

According to an embodiment of the present invention, as shown in fig. 1, a hydroxyacetonitrile amination apparatus comprises:

a premixing unit 1 for receiving and mixing reaction raw materials; the pre-mixing unit comprises a micro-scale pre-mixer;

the multistage reaction unit is arranged at the downstream of the premixing unit 1 and used for receiving the mixed reaction raw materials; the multistage reaction unit comprises multistage reactors which are sequentially connected in series, and the reaction temperature in the multistage reactors is controlled to be gradually increased; and the reaction temperature in the primary reactor 2 is controlled to be greater than the mixing temperature in the premixing unit 1.

According to the embodiment, the premixing unit enables the reaction raw materials to be uniformly mixed in a microscale manner, so that side reactions are avoided in the mixing process, and the self-polymerization of the hydroxyacetonitrile caused by non-uniform reactions is avoided to generate colored polymers. And a multistage reactor is arranged for carrying out stage temperature control, and the temperature is gradually increased, so that the side reaction in the reaction process can be fundamentally avoided, the reaction efficiency is improved, the yield of the aminoacetonitrile is ensured, and the method is suitable for industrial production.

Referring to fig. 2, the micro-scale premixer includes a fluid distributor 10, a fluid homogenizer 11; the fluid distributor 10 is arranged at the front end of the fluid homogenizer 11 along the fluid flowing direction (as shown by the arrow in fig. 2) and is communicated with the fluid homogenizer 11.

With further reference to fig. 3, a plurality of distribution holes 100 are formed in a side wall of the fluid distributor, which is in compliance with the fluid flowing direction, so that the fluid of the reaction material flows out through the distribution holes 100 in the side wall along the direction indicated by the arrow in fig. 2; the fluid homogenizer 11 comprises a plurality of rotational flow mixing units, and any rotational flow mixing unit adopts a forward rotation unit 111 or a differential rotation unit 112. The normal rotation unit 111 and the abnormal rotation unit 112 in the fluid homogenizer 11 are arranged in a crossing manner.

In order to further improve the uniform mixing effect on the micro-scale, the length h of any one of the rotational flow mixing units is 0.5-2 times of the diameter D of the fluid homogenizer, and the rotation angle (torsion angle for short) of the rotating blades in the forward rotation unit 111 or the differential rotation unit 112 is 160-180 degrees. Referring to fig. 3 and 4, the distribution holes 100 are concentrated on the sidewall of the fluid distributor facing the fluid flowing direction, and the distribution holes 100 are located on the side of the fluid distributor 10 facing the fluid flowing direction, and the included angle α of the interface ranges from 90 ° to 160 ° within the arc length corresponding to the included angle α (as shown in fig. 3). More preferably, the aperture of the distribution holes 100 is 1-10 mm, the distribution holes 100 are arranged in a regular triangle, and the distance between the distribution holes 100 is 1.5-2 times of the aperture. In addition, the distance B between the distribution holes 100 and the adjacent rotational flow mixing units is 0.5-2 times of the diameter of the fluid homogenizer.

Based on the above, by adding excessive ammonia water into the fluid homogenizer in the micro-scale premixer, the hydroxyacetonitrile enters the fluid distributor 10 in the micro-scale premixer, and is distributed into the ammonia water at high speed in the fluid flowing direction in the fluid homogenizer 11 through the distribution holes 100, so as to form uniform shearing and rapid mixing on the ammonia water in the whole flowing section; and (3) shearing and mixing the roughly mixed fluid by normal rotation and abnormal rotation through a rotational flow mixing unit to achieve uniform mixing of the hydroxyacetonitrile and the ammonia water, and reducing the non-uniform coefficient to be below 0.005%.

In the process of realizing the process, the multistage reaction unit is a tubular reactor which is connected in series in a multistage way. And the reactors are 2-5 stages connected in series. Preferably, the diameter of the reaction tube in the tubular reactor is 5-50 mm, wherein the optimal range is 10-25 mm.

In addition, the premixing unit 10 and any stage of reaction unit are provided with a temperature detector and a heat exchange medium automatic control valve, and the device is also provided with an automatic control system which is electrically connected with the temperature detector and the heat exchange medium automatic control valve and is used for independently controlling the reaction temperature in the premixing unit and each reaction unit. The grading control of each grade of units is realized, the occurrence of side reaction is further reduced, the reaction yield and efficiency are improved, and the industrial production is realized.

In order to obtain the effect of industrial production, the temperature in the micro-scale premixer is controlled to be 5-15 ℃, the pressure is controlled to be within the range of 0.1-1.5MPa, and the retention time is 1-2 s.

Based on the consideration of reaction efficiency and cost, the multistage reaction unit is preferably set as a 3-stage tubular reactor in series connection; controlling the temperature in the primary reactor 2 to be 20-50 ℃ and the retention time to be 3-10 s; controlling the temperature in the secondary reactor 3 to be 40-60 ℃ and the retention time to be 2-4 mins; the temperature in the three-stage reactor 4 is controlled to be 50-70 ℃, and the retention time is 2-4 mins.

In practical application, the outlet and the inlet of each stage of reactor are provided with temperature detectors, and the temperature difference between the outlet temperature and the inlet temperature is controlled to be less than 5 ℃ so as to strictly control the temperature of the reactor.

According to another embodiment provided by the invention, the invention provides a hydroxyacetonitrile ammoniation reaction process, which comprises the following steps:

s1, uniformly mixing the hydroxyacetonitrile and ammonia water in a premixing unit;

and S2, gradually feeding the uniformly mixed mixture of the hydroxyacetonitrile and the ammonia water into a multistage reactor, wherein the reaction temperature in the first-stage reactor 2 is controlled to be higher than the mixing temperature in the premixing unit, and the reaction temperature in the multistage reactor is controlled to be gradually increased.

As a preferred embodiment, in step S1, the excessive ammonia water is added into the fluid homogenizer 11 in the micro-scale premixer, the hydroxyacetonitrile enters the fluid distributor 10 in the micro-scale premixer, and is distributed into the ammonia water at a high speed along the fluid flow direction in the fluid homogenizer 11 through the distribution holes 100, so as to form uniform shearing and rapid mixing on the ammonia water in the whole flow cross section; and shearing and mixing the roughly mixed fluid by a rotational flow mixing unit to achieve uniform mixing of the hydroxyl acetonitrile and the ammonia water, and reducing the non-uniform coefficient to be below 0.005%.

The ammoniation of the hydroxyacetonitrile is a key step of a process route of the hydroxyacetonitrile method, and the selectivity and the by-product of the step directly determine the yield of the glycine and also determine the energy consumption and the operation cost of the whole process. The main reaction is as follows: HOCH₂CN+NH₃→NH₂CH₂CN+H₂O。

Preferably, in step S1, the mixing temperature in the premixing unit is controlled within the range of 5-15 ℃, the pressure is controlled within the range of 0.1-1.5MPa, and the residence time is 1-2S. Through the mixing process, on one hand, the temperature is controlled in a lower proper range, on the other hand, the extremely high uniform mixing degree is realized, and the condition of generating local hydroxyacetonitrile enrichment is avoided, so that the side reaction of the hydroxyacetonitrile polymerization and the coloring of the reaction liquid is avoidedAnd (4) generating.

In the step S2, the uniformly mixed mixture of the hydroxyacetonitrile and the ammonia water enters the primary reactor 2, wherein the temperature in the primary reactor 2 is controlled to be 20-50 ℃, the retention time is 3-10S, the occurrence probability of byproducts is reduced in the range, the yield is low, and the reaction efficiency is ensured. Controlling the temperature in the secondary reactor 3 to be 40-60 ℃ and the retention time to be 2-3 mins so as to improve the reaction rate; the temperature in the three-stage reactor 4 is controlled to be 50-70 ℃, and the retention time is 2-4 mins, so that the reaction rate is improved. It should be noted that the pressure in the premixing unit is taken out of the natural pressure drop of the fluid, i.e. as the reaction pressure in the multistage reactor.

The invention adopts a special structural design to carry out low-temperature mixing in the premixing unit, combines the graded reaction temperature control on the basis of highly uniform mixing, controls the temperature to be 20-50 ℃ in the initial reaction stage, and can avoid the side reaction of producing the nitrilotriacetonitrile by the reaction of 3 pieces of hydroxyacetonitrile and 1 piece of ammonia on the premise of ensuring the reaction yield: 3HOCH₂CN+NH₃→(CH₂CN)₃N+3H₂And O. The generation of this side reaction leads to a lower glycine yield. While avoiding the side reaction of reacting 2 molecules of hydroxyacetonitrile with ammonia to form iminodiacetonitrile: 2HOCH₂CN+NH₃→NH(CH₂CN)₂+2H₂O, although iminodiacetonitrile/acid can also be sold as a product and the price is equivalent to that of glycine, excessive iminodiacetonitrile production not only leads to increased energy consumption for subsequent separation; and iminodiacetonitrile can generate self-polymerization at high temperature,producing a colored group. Meanwhile, the reaction efficiency can be improved by increasing the subsequent reaction temperature.

In the process for synthesizing glycine by the hydroxyacetonitrile method, side reactions generated in the reaction of forming aminoacetonitrile after ammoniation of the hydroxyacetonitrile are main reasons for generating colored groups and low yield of the glycine, and the subsequent side reactions in the two-step reaction of producing sodium glycinate by alkaline hydrolysis of the aminoacetonitrile and producing the glycine by reacting the sodium glycinate with sulfuric acid have small influence, so that the method is not discussed in detail for the subsequent two steps.

In the above embodiment, the reaction raw materials include hydroxyacetonitrile and ammonia water, and the ratio of hydroxyacetonitrile: the concentration is 40-50 wt% (the rest is water). The concentration of the hydroxy acetonitrile is not high, and if the concentration is high, polymerization is easy to cause; too low, increases subsequent separation costs; ammonia water: the concentration of the ammonia water is 20-35 wt%, the concentration of the ammonia water is too low, and the energy consumption for later separation is high; too high, will raise the recovery and recycling cost of ammonia.

Several specific examples are provided below:

comparative example 1:

raw materials of the catalyst comprise 543g of hydroxyacetonitrile (with the concentration of 42 wt%) and 1183g of ammonia water (with the concentration of 23 wt%).

The device comprises the following steps: conventional line mixer + single-tube reactor, reactor diameter 5 mm.

The technological parameters are as follows: the reaction temperature is 83 ℃, the pressure is 1.3MPa (g), and the retention time is 6mins

And (3) reaction results: the yield of the aminoacetonitrile is 89%, the by-products and the oligomers are 11%, and the consumption of the activated carbon of 4% is needed for subsequent decolorization.

Comparative example 2:

raw materials of the catalyst comprise 4220kg of hydroxyacetonitrile (with the concentration of 42wt percent) and 9200kg of ammonia water (with the concentration of 23wt percent).

The device comprises the following steps: conventional mixer + single-tube reactor, reactor diameter 200 mm.

The technological parameters are as follows:

premixing in a conventional mixer: temperature is not controlled, room temperature and pressure is 1.3MPa (g);

single-tube reactor: the temperature is 83 ℃, the pressure is 1.3MPa (g), and the retention time is 6 mins.

And (3) reaction results: the yield of the aminoacetonitrile is 80 percent, the by-products and the oligomers are 20 percent, and the consumption of the activated carbon is 5 percent for subsequent decolorization.

The above comparative example 2 is an enlarged example of comparative example 1, resulting in a lower yield, an increase in reaction by-products, and an increase in consumption of activated carbon for decoloring.

With the apparatus and process of the present invention, for example:

example 1

Raw materials: same as in comparative example 1.

The device comprises the following steps: the micro-scale premixer and the three-stage tubular reactor are connected in series, and the diameter of the reaction tube in the reactor is 5 mm.

The technological parameters are as follows:

premixing in micro-scale premixer: the temperature is 10 ℃, the pressure is 1.3MPa (g), and the retention time is 1-2 s;

reaction at each stage in the reactor: the temperature of the primary reactor is 40 ℃, and the retention time is 4 s; the temperature of the secondary reactor is 50 ℃, and the retention time is 2.5 mins; the temperature of the three-stage reactor is 60 ℃, and the retention time is 3.5 mins; wherein the pressure is 1.1 to 1.3MPa (g).

And (3) reaction results: the yield of the aminoacetonitrile is 94.3 percent, the by-products and the oligomers are 5.7 percent, and the consumption of the activated carbon of 1 percent is needed for the subsequent decolorization.

Example 2:

raw materials: same as in comparative example 2.

The device comprises the following steps: a micro-scale premixer and a three-stage series-connected tubular reactor; wherein: the diameter of a distribution hole 100 of a fluid distributor 10 of the micro-scale premixer is 5mm, the flow velocity of a fluid outlet is 3-5 m/s, a fluid homogenizer 11 comprises 8 rotational flow mixing units which are alternately arranged by a normal rotation unit and a differential rotation unit, the flow velocity of the mixed fluid in the fluid distributor 10 is 1.0-2.5 m/s, and the retention time in the fluid distributor 10 is controlled within 2 s; the diameter of the reaction tube in each stage reactor was 19 mm.

The technological parameters are as follows:

premixing in micro-scale premixer: temperature 10 ℃, pressure 1.3MPa (g); the retention time is 1-2 s;

reaction at each stage in the reactor: the temperature of the primary reactor is 40 ℃, and the retention time is 4 s; the temperature of the secondary reactor is 50 ℃, and the retention time is 2.5 mins; the temperature of the three-stage reactor is 60 ℃, and the retention time is 3.5 mins; wherein the pressure is 1.1 to 1.3MPa (g).

And (3) reaction results: the yield of the aminoacetonitrile is 95.5 percent, the by-products and the oligomers are 4.5 percent, and the subsequent decolorization needs 1 percent of the consumption of the active carbon.

Example 3:

raw materials: same as in comparative example 2.

The device comprises the following steps: a micro-scale premixer and a three-stage series-connected tubular reactor; wherein: the diameter of a distribution hole 100 of a fluid distributor 10 of the micro-scale premixer is 10mm, the flow velocity of a fluid outlet is 2-4 m/s, a fluid homogenizer 11 comprises 10 rotational flow mixing units which are alternately arranged by a normal rotation unit and a differential rotation unit, the flow velocity of the mixed fluid in the fluid distributor 11 is 1.0-2.5 m/s, and the residence time in the fluid distributor is controlled within 2 s; the diameter of the reaction tube in each stage reactor was 19 mm.

Premixing in micro-scale premixer: the temperature is 10 ℃, the pressure is 1.3MPa (g), and the retention time is 1-2 s;

reaction at each stage in the reactor: the temperature of the primary reactor is 40 ℃, and the retention time is 4 s; the temperature of the secondary reactor is 50 ℃, and the retention time is 2.5 mins; the temperature of the three-stage reactor is 60 ℃, and the retention time is 3.5 mins; the pressure is 1.1 to 1.3MPa (g).

And (3) reaction results: the yield of the aminoacetonitrile is 95.4 percent, the by-products and the oligomers are 4.6 percent, and the consumption of the activated carbon of 1 percent is needed for the subsequent decolorization.

Example 4:

raw materials: same as in comparative example 2.

The device comprises the following steps: the method is basically the same as the embodiment 2, and is different only in that: the diameter of the reaction tube in each stage of the reactor was 25 mm.

The technological parameters are as follows:

premixing in micro-scale premixer: the temperature is 10 ℃, the pressure is 1.3MPa (g), and the retention time is 1-2 s;

reaction at each stage in the reactor: the temperature of the primary reactor is 40 ℃, and the retention time is 4 s; the temperature of the secondary reactor is 50 ℃, and the retention time is 2.5 mins; the temperature of the three-stage reactor is 60 ℃, and the retention time is 3.5 mins; the pressure is 1.1 to 1.3MPa (g).

And (3) reaction results: the yield of the aminoacetonitrile is 95.2 percent, the by-products and the oligomers are 4.8 percent, and the consumption of the activated carbon of 1 percent is needed for the subsequent decolorization.

Example 5:

raw materials: same as in comparative example 2.

The device comprises the following steps: same as in example 3.

The technological parameters are as follows:

premixing in micro-scale premixer: the temperature is 15 ℃, the pressure is 0.3MPa (g), and the retention time is 1-2 s;

reaction at each stage in the reactor: the temperature of the primary reactor is 45 ℃, and the retention time is 4 s; the temperature of the secondary reactor is 55 ℃, and the retention time is 3 mins; the temperature of the three-stage reactor is 60 ℃, and the retention time is 3 mins; the pressure is 0.1 to 0.3MPa (g).

And (3) reaction results: the yield of the aminoacetonitrile is 95.0 percent, the by-products and the oligomers are 5.0 percent, and the consumption of the activated carbon of 1 percent is needed for the subsequent decolorization.

Example 6:

raw materials: same as in comparative example 2.

The device comprises the following steps: same as in example 2.

The technological parameters are as follows:

premixing in micro-scale premixer: the temperature is 15 ℃, the pressure is 0.8MPa (g), and the retention time is 1-2 s;

reaction at each stage in the reactor: the reaction pressure is 0.6-0.8 MPa (g), the temperature of the primary reactor is 45 ℃, and the retention time is 4 s; the temperature of the secondary reactor is 55 ℃, and the retention time is 3 mins; the temperature of the three-stage reactor is 60 ℃, and the retention time is 3 mins.

And (3) reaction results: the yield of the aminoacetonitrile is 95.1 percent, the by-products and the oligomers are 4.9 percent, and the consumption of the activated carbon of 1 percent is needed for the subsequent decolorization.

Example 7:

raw materials: same as in comparative example 2.

The device comprises the following steps: the method is basically the same as the embodiment 2, and is different only in that: the reactor tubes in each stage of the reactor were 10mm in diameter.

The technological parameters are as follows:

premixing in micro-scale premixer: the temperature is 15 ℃, the pressure is 1.3MPa (g), and the retention time is 1-2 s;

reaction at each stage in the reactor: the reaction pressure is 1.1-1.3 MPa (g), the temperature of the primary reactor is 40 ℃, and the retention time is 6 s; the temperature of the secondary reactor is 55 ℃, and the retention time is 3 mins; the temperature of the three-stage reactor is 60 ℃, and the retention time is 3.0 mins.

And (3) reaction results: the yield of the aminoacetonitrile is 95.8 percent, the by-products and the oligomers are 4.2 percent, and the consumption of the activated carbon of 1 percent is needed for the subsequent decolorization.

Example 8:

raw materials: same as in comparative example 2.

The device comprises the following steps: the method is basically the same as the embodiment 2, and is different only in that: the reactor tubes in each stage reactor were 32mm in diameter.

The technological parameters are as follows:

premixing in micro-scale premixer: the temperature is 15 ℃, the pressure is 1.0MPa (g), and the retention time is 1-2 s;

reaction at each stage in the reactor: the reaction pressure is 0.8-1.0 MPa (g), the temperature of the primary reactor is 40 ℃, and the retention time is 3 s; the temperature of the secondary reactor is 50 ℃, and the retention time is 4 mins; the temperature of the three-stage reactor is 65 ℃, and the retention time is 3.0 mins;

and (3) reaction results: the yield of the aminoacetonitrile is 94.7 percent, the by-products and the oligomers are 5.3 percent, and the subsequent decolorization needs 1 percent of the consumption of the active carbon.

Example 9:

raw materials: same as in comparative example 2.

The device comprises the following steps: same as in example 2.

The technological parameters are as follows:

premixing in micro-scale premixer: the temperature is 15 ℃, the pressure is 0.5MPa (g), and the retention time is 1-2 s;

reaction at each stage in the reactor: the reaction pressure is 0.3-0.5 MPa (g), the temperature of the primary reactor is 20 ℃, and the retention time is 4 s; the temperature of the secondary reactor is 40 ℃, and the retention time is 4 mins; the temperature of the three-stage reactor is 50 ℃, and the retention time is 4.0 mins.

And (3) reaction results: the yield of the aminoacetonitrile is 94.6 percent, the by-products and the oligomers are 5.4 percent, and the consumption of the activated carbon of 1 percent is needed for the subsequent decolorization.

Example 10:

raw materials: same as in comparative example 2.

The device comprises the following steps: same as in example 2.

The technological parameters are as follows:

premixing in micro-scale premixer: the temperature is 5 ℃, the pressure is 1.5MPa (g), and the retention time is 1-2 s;

reaction at each stage in the reactor: the pressure is 1.3-1.5 MPa (g), the temperature of the primary reactor is 50 ℃, and the retention time is 5 s; the temperature of the secondary reactor is 60 ℃, and the retention time is 3 mins; the temperature of the three-stage reactor is 70 ℃, and the retention time is 2.0 mins.

And (3) reaction results: the yield of the aminoacetonitrile is 94.2 percent, the by-products and the oligomers are 5.8 percent, and the subsequent decolorization needs 2 percent of the consumption of the activated carbon.

Comparative example 10-1

Raw materials: same as in comparative example 2.

The device comprises the following steps: same as in example 2.

The technological parameters are as follows:

premixing in micro-scale premixer: the temperature is 25 ℃, the pressure is 1.3MPa (g), and the retention time is 1-2 s;

reaction at each stage in the reactor: the reaction pressure is 1.5MPa (g), the temperature of the primary reactor is 55 ℃, and the retention time is 5 s; the temperature of the secondary reactor is 65 ℃, and the retention time is 4 mins; the temperature of the three-stage reactor is 70 ℃, and the retention time is 2.0 mins.

And (3) reaction results: the yield of the aminoacetonitrile is 89.2 percent, the by-products and the oligomers are 10.8 percent, and the subsequent decolorization needs 4 percent of the consumption of the activated carbon.

It should be noted that the above embodiments can be freely combined as necessary. The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.