CN108295500B - Crystallization apparatus and crystallization method - Google Patents
Crystallization apparatus and crystallization method Download PDFInfo
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- CN108295500B CN108295500B CN201810150183.3A CN201810150183A CN108295500B CN 108295500 B CN108295500 B CN 108295500B CN 201810150183 A CN201810150183 A CN 201810150183A CN 108295500 B CN108295500 B CN 108295500B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/02—Crystallisation from solutions
- B01D9/04—Crystallisation from solutions concentrating solutions by removing frozen solvent therefrom
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D9/00—Crystallisation
- B01D9/0004—Crystallisation cooling by heat exchange
- B01D9/0009—Crystallisation cooling by heat exchange by direct heat exchange with added cooling fluid
Abstract
The invention discloses crystallization equipment and a crystallization method. The crystallization equipment is provided with at least one fluid channel, one end of the fluid channel is provided with a feed inlet, the fluid channel is sequentially divided into a conveying section, a mixing section and a crystal growth section along the flowing direction of feed liquid, the conveying section is used for conveying the feed liquid to the mixing section, the side wall of one end, away from the crystal growth section, of the mixing section is also provided with a cooling medium inlet, the cooling medium inlet is used for conveying a cooling medium into the mixing section, the mixing section is used for mixing the feed liquid and the cooling medium, cooling the feed liquid and enabling the feed liquid to generate supersaturation and to precipitate crystals, and the crystal growth section is used for growing the crystals and obtaining suspension containing solute particles; the other end of the fluid channel is also provided with a discharge hole which is used for continuously discharging the suspension out of the fluid channel. The crystallization equipment and the crystallization method can rapidly generate larger supersaturation degree and more uniform supersaturation degree distribution, thereby preparing crystal particle products with narrow particle size distribution and small average particle size.
Description
Technical Field
The invention relates to crystallization equipment and a crystallization method.
Background
The method for precipitating crystals from a solution mainly comprises a cooling crystallization method, a solvent evaporation crystallization method and an anti-solvent method, wherein the cooling crystallization method has the advantages of low cost, simple operation and the like, and thus, the method has wide application in industrial production. The cooling crystallization method is divided into dividing wall type cooling crystallization and direct contact type cooling crystallization.
The research and industrial application of the dividing wall type cooling crystallization are more, and the method generally comprises the following steps: and introducing a coolant into a jacket or an inner coil of the stirring kettle, and gradually generating supersaturation in the cooling process so as to precipitate crystals. Because the cooling process generally requires a long time, the formed supersaturation degree is relatively small, and the crystal particles obtained are often large, in order to overcome the defect, many researchers improve the crystallization process by improving the heat transfer efficiency, accelerating the cooling process and increasing the supersaturation degree, for example, patent document CN202107543U discloses a method for improving the heat transfer efficiency by adding an inner water tank in a crystallization kettle, thereby improving the production efficiency of copper sulfate; patent document CN205323274U discloses a coil cooling crystallizer, which has the characteristics of large heat exchange area and high crystallization efficiency; patent document CN205549661U discloses a method for continuously cooling the citric acid solution in the crystallizer by means of pump circulation, thereby improving the continuity and stability of the product quality. The dividing wall type cooling crystallization method disclosed by the patent mostly increases heat exchange components or heat exchange areas, so that the heat transfer rate in the cooling process is improved, and the formation of supersaturation degree in the crystallization process is accelerated. However, because of the kettle crystallizer, the cooling process is often between several minutes and several hours, the nucleation step of the crystallization process usually occurs in microseconds or less, and the higher supersaturation is favorable for the nucleation, while the environment with low supersaturation is favorable for the growth process of the crystal nucleus, and because of the limitation of the cooling rate, the supersaturation degree is often smaller in the initial crystallization stage, the nucleation rate is lower, and the process mainly takes crystal growth as the main process, so the particles of the final crystallization product are larger. In addition, the kettle crystallizer often has the problem of uneven local heat distribution, which can cause uneven supersaturation distribution, so that the particle size of the final crystallized product is uneven, and the particle size distribution is difficult to control. Meanwhile, the dividing wall type crystallizer is adopted, crystal scale is easily formed on the wall surface of the wall or the wall surface of the heat exchange coil, and therefore the heat transfer efficiency is reduced.
The direct contact type cooling crystallization is that a coolant is in direct contact with a solution in a crystallizer for heat exchange, and the coolant absorbs heat to overcool the solution, so that supersaturation is generated, crystal nuclei are formed, and crystals grow up. Compared with the dividing wall type cooling crystallization, the method has the characteristics of energy conservation, no need of arranging a heat exchange surface, no scar, no particle breakage and the like, so the conception has wide application prospect in industrial production. For example, patent document CN104557436A discloses a method for directly introducing a low-temperature refrigerant into a crystallization tank to directly contact with a xylene solution for heat exchange to obtain a high-purity paraxylene product, which solves the problems of high cost and low heat exchange efficiency in the prior art. Patent document CN102515254A uses the cooled zinc sulfate mother liquor to directly add into the high-temperature zinc sulfate saturated solution for rapid cooling to obtain zinc sulfate crystals, which greatly accelerates the cooling speed. However, these methods still operate in a kettle-type crystallizer, and have the problems of insufficient contact heat exchange of hot and cold media, long heat exchange and cooling time, uneven distribution of supersaturation degree, and the like, so that the particle size control of the crystallized product is difficult.
Disclosure of Invention
The invention aims to overcome the defects of large grain diameter and wide grain diameter distribution of a crystallized product caused by small supersaturation degree and uneven distribution due to low heat exchange efficiency, slow cooling process, uneven local heat distribution and the like of the conventional cooling crystallization method, and provides crystallization equipment and a crystallization method. According to the crystallization equipment and the crystallization method, the feed liquid containing the solute and the solvent is adopted to exchange heat with the cooling medium in a direct contact manner, so that the heat exchange efficiency is high, the temperature reduction process is fast, the heat distribution is uniform, and larger supersaturation degree and more uniform supersaturation degree distribution compared with the prior art can be rapidly generated, so that crystal particle products with narrow particle size distribution and small average particle size are prepared, and means such as grinding and crushing are not needed.
The invention solves the technical problems through the following technical scheme:
the invention provides crystallization equipment which is provided with an equipment main body, wherein the equipment main body is provided with at least one fluid channel, one end of the fluid channel is provided with a feed inlet, the feed inlet is used for continuously feeding feed liquid containing solute and solvent I into the fluid channel, the fluid channel is sequentially divided into a conveying section, a mixing section and a crystal growth section along the flow direction of the feed liquid, the conveying section is used for conveying the feed liquid to the mixing section, the side wall of one end, away from the crystal growth section, of the mixing section is also provided with a cooling medium inlet, the cooling medium inlet is used for conveying a cooling medium into the mixing section, the mixing section is used for mixing the feed liquid and the cooling medium, cooling the feed liquid and enabling the feed liquid to generate supersaturation and separate out crystals, and the crystal growth section is used for growth of the crystals, And obtaining a suspension containing solute particles; and the other end of the fluid channel is also provided with a discharge hole, and the discharge hole is used for continuously discharging the suspension out of the fluid channel.
In the present invention, preferably, the fluid channel is an internal cavity surrounded by a circular tube, the upper end of the circular tube is the feed inlet, the lower end of the circular tube is the discharge outlet, and the cooling medium inlet is arranged on the side wall of the circular tube. In the technical scheme, the feed liquid entering from the feed inlet is in cross flow contact with the cooling medium entering from the cooling medium inlet, so that the feed liquid can be cooled more quickly, and supersaturation and uniform supersaturation distribution can be generated more quickly, thereby preparing crystal particles with narrow particle size distribution and small average particle size.
In the present invention, preferably, the ratio of the height to the diameter of the crystallization apparatus is 10 to 200, and for example, the ratio of the height to the diameter of the fluid channel may be 17.5, 21.7, 30 or 35.
In the present invention, the solvent I is a solvent capable of dissolving the solute.
In the present invention, preferably, the mixing section is provided with more than two cooling medium inlets, and the cooling medium inlets are uniformly distributed on the side wall of the mixing section, for example, 4 to 6 cooling medium inlets may be provided. More preferably, the cooling medium inlet is one or more of a circular hole, a non-annular gap and a high-pressure nozzle. More preferably, the cooling medium inlet is configured as a circular hole, a non-annular gap, or a high-pressure nozzle.
In the present invention, preferably, the mixing section has an annular gap. More preferably, the height of the annular gap is 0.1mm to 10mm, and may be 3mm, for example.
In the present invention, preferably, the crystallization apparatus is further provided with a buffer chamber, the buffer chamber is annularly disposed outside the cooling medium inlet and completely attached to the apparatus main body, the buffer chamber is further provided with a cooling medium inlet, the cooling medium inlet is used for continuously introducing a cooling medium into the buffer chamber, and the buffer chamber is used for storing the cooling medium and uniformly providing the cooling medium to the cooling medium inlet.
In the present invention, preferably, the crystal growth section is provided with a fin and/or a baffle, and the fin and/or the baffle are used for enhancing the micro-mixing effect of the crystal growth section. The arrangement of the fins and/or the baffle can enable the supersaturation degree distribution of the feed liquid to be more uniform, so that crystal particles with more uniform particle size distribution are obtained.
The invention also provides a crystallization method adopting the crystallization equipment, which comprises the following steps:
feed liquid containing solute and solvent I continuously enters the fluid channel through the feed inlet, and cooling medium continuously entering from the cooling medium inlet is mixed with the feed liquid in the mixing section, cooled and supersaturated, so that crystals are precipitated;
and the crystal continues to grow in the crystal growth section, and a suspension containing solute particles is obtained, and the suspension is continuously discharged out of the fluid channel from the discharge port.
In the invention, the feed liquid should have the following characteristics: the solubility of the solute in the solvent decreases with decreasing temperature, and the temperature of the feed liquid is not higher than the boiling point of the feed liquid. Preferably, the feed liquid can also contain a surfactant.
In the present invention, generally, the flow state of the feed liquid in the fluid channel before mixing with the cooling medium is turbulent, the flow state of the mixed liquid obtained after mixing the feed liquid with the cooling medium in the fluid channel is turbulent, and the term "turbulent flow" refers to a reynolds number Re greater than 2000.
In the present invention, preferably, the cooling medium is the solvent I and/or a solvent II immiscible with the solvent I.
In the present invention, preferably, a ratio of a flow rate of the cooling medium entering through the cooling medium inlet to a flow rate of the feed liquid entering through the feed port is 1 or more. More preferably, the ratio of the flow rate of the cooling medium entering through the cooling medium inlet to the flow rate of the feed liquid entering through the feed port is 2-10, and may be, for example, 2.8, 6.3, 7.4 or 9.4.
In the present invention, preferably, the residence time of the feed liquid and the cooling medium in the mixing section is not more than 100 milliseconds. More preferably, the residence time of the feed liquid and the cooling medium in the mixing section is not more than 20 milliseconds. Even more preferably, the residence time of the feed liquid and the cooling medium in the mixing section is no greater than 10 milliseconds. The residence time of the feed liquid and the cooling medium in the mixing section may be, for example, 12ms, 15ms or 23 ms. According to the technical scheme, the rapid cooling of the feed liquid in millisecond time scale can be realized, and the supersaturation degree distribution with larger supersaturation degree and more uniform distribution is generated, so that the crystal particle product with narrower particle size distribution and smaller average particle size is prepared.
In the present invention, the residence time of the feed liquid in the fluid channel is preferably not more than 10 seconds, and may be 87ms, 100ms, 130ms or 452ms, for example.
In the present invention, preferably, the suspension is filtered and dried to obtain a powder product of solute particles. It should be noted here that the solvent obtained after filtration can be recycled after purification.
The above preferred conditions can be arbitrarily combined to obtain preferred embodiments of the present invention without departing from the common general knowledge in the art.
The reagents and starting materials used in the present invention are commercially available.
The positive progress effects of the invention are as follows: the invention provides crystallization equipment and a crystallization method. According to the crystallization equipment and the crystallization method, the feed liquid containing the solute and the solvent is adopted to exchange heat with the cooling medium in a direct contact manner, so that the heat exchange efficiency is high, the temperature reduction process is fast, the heat distribution is uniform, and larger supersaturation degree and more uniform supersaturation degree distribution compared with the prior art can be rapidly generated, so that crystal particle products with narrow particle size distribution and small average particle size are prepared, and means such as grinding and crushing are not needed.
Drawings
FIG. 1 is a schematic view of the structure of a crystallization apparatus in example 1;
FIG. 2 is a view from the A-A direction of the crystallization apparatus in FIG. 1;
FIG. 3 is a schematic view of the structure of a crystallization apparatus of example 2;
FIG. 4 is a view from the B-B direction of the crystallization apparatus in FIG. 3;
FIG. 5 is a schematic view of the structure of a crystallization apparatus of example 3;
FIG. 6 is a view from the C-C direction of the crystallization apparatus in FIG. 5;
FIG. 7 is a schematic view of the constitution of a crystallizing device of example 4;
FIG. 8 is a D-D view of the crystallization apparatus of FIG. 7;
FIG. 9 is a schematic view of the crystallization apparatus and the crystallization method of examples 1 to 4.
Description of reference numerals:
Conveying section 20
Mixing section 30
Cooling medium inlet 50
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.
In the following examples, the solubility of the solute in the feed liquid in the solvent decreases with decreasing temperature, and the temperature of the feed liquid is not higher than the boiling point of the feed liquid; the cooling medium is a solvent immiscible with the solvent I.
In the following embodiments, the flow state of the feed liquid in the fluid passage before mixing with the cooling medium is turbulent, the flow state of the mixed liquid obtained after mixing with the cooling medium in the fluid passage is turbulent, and "turbulent" herein means that the reynolds number Re is greater than 2000.
In the following embodiments, the aspect ratio of the crystallization apparatus refers to the ratio of the length of the fluid passage to the inner diameter of the fluid passage.
Example 1
(1) Crystallization equipment
The crystallization apparatus as shown in fig. 1, the crystallization apparatus has an apparatus main body, the apparatus main body has a fluid channel, one end of the fluid channel is provided with a feed inlet 10, the feed inlet 10 is used for continuously feeding a feed liquid containing solute and solvent I into the fluid channel, the fluid channel is sequentially divided into a conveying section 20, a mixing section 30 and a crystal growth section 40 along the flow direction of the feed liquid, the conveying section 20 is used for conveying the feed liquid to the mixing section 30, the side wall of the mixing section 30 at one end far away from the crystal growth section 40 is further provided with a cooling medium inlet 50, the cooling medium inlet 50 is used for conveying a cooling medium into the mixing section 30, the mixing section 30 is used for mixing the feed liquid and the cooling medium, cooling the feed liquid and enabling the feed liquid to generate supersaturation and precipitate crystals, and the crystal growth section 40 is used for crystal growth and obtaining a suspension containing solute; the other end of the flow channel is also provided with a discharge port 60, and the discharge port 60 is used for continuously discharging the suspension out of the flow channel.
The fluid channel is an internal cavity surrounded by a round pipe, the upper end of the round pipe is a feed inlet 10, the lower end of the round pipe is a discharge outlet 60, the inner diameter of the round pipe is 10mm, the height of the round pipe is 300mm, the height-diameter ratio of the crystallization equipment is 30, the number of the cooling medium inlets 50 is 4, the cooling medium inlets are uniformly distributed on the side wall of the round pipe, the structure of the cooling medium inlet is a small hole, the diameter of the small hole is 4mm, and the distance from the center line of the small hole to the discharge outlet 60 is 250mm (shown in figure 2).
The crystallization equipment is further provided with a buffer chamber 70, the buffer chamber 70 is annularly arranged outside the cooling medium inlet 50 and is completely attached to the equipment main body, the buffer chamber 70 is further provided with a cooling medium main inlet 71, the cooling medium main inlet 71 is used for continuously introducing cooling medium into the buffer chamber 70, and the buffer chamber 70 is used for storing the cooling medium and uniformly providing the cooling medium to the cooling medium inlet 50.
(2) Crystallization method
The crystallization method using the crystallization apparatus shown in fig. 9 comprises the following steps:
feed liquid consisting of solute and solvent I continuously enters the fluid channel through the feed inlet 10, and cooling medium continuously entering from the cooling medium inlet 50 is mixed with the feed liquid in the mixing section 30, cooled and generates supersaturation, so that crystals are precipitated;
the crystal continues to grow in the crystal growth section 40 and a suspension containing solute particles is obtained, which is continuously withdrawn from the flow channel through the discharge port 60.
Wherein, the feed liquid entering from the feed inlet 10 is 60 ℃ ammonium perchlorate aqueous solution (namely, the solute is ammonium perchlorate, and the solvent I is water), the concentration of ammonium perchlorate in the feed liquid is 350g/L, the flow rate of the feed liquid is 120L/h, and the corresponding flow rate is 0.42 m/s; the cooling medium is dichloromethane with the temperature of-18 ℃, the cooling medium enters the buffer chamber 70 through the cooling medium total inlet 71 and enters the mixing section 30 through the cooling medium inlet 50, the total flow rate of the cooling medium entering the mixing section 30 is 480L/h, and the flow rate of the cooling medium in each cooling medium inlet 50 is 2.65 m/s; the ratio of the flow rate of the cooling medium entering through the cooling medium inlet 50 to the flow rate of the feed liquid entering through the feed inlet 10 is 6.3; the residence time of the feed liquid and the cooling medium in the mixing section 30 is 12 milliseconds; the residence time of the feed liquid in the flow channel was 100 milliseconds.
Sampling after the flow control of the crystallization equipment is stable, and filtering to obtain ammonium perchlorate crystals.
Effect data: the particle size distribution is 6-50 μm, and the volume median diameter d is determined by Malvern particle size analyzer0.5＝22μm。
Example 2
As shown in fig. 3, the crystallization apparatus has an apparatus main body, the apparatus main body has a fluid channel, one end of the fluid channel is provided with a feed inlet 10, the feed inlet 10 is used for continuously feeding a feed liquid containing solute and solvent I into the fluid channel, the fluid channel is sequentially divided into a conveying section 20, a mixing section 30 and a crystal growth section 40 along the flow direction of the feed liquid, the conveying section 20 is used for conveying the feed liquid to the mixing section 30, the side wall of the mixing section 30 at the end far away from the crystal growth section 40 is further provided with a cooling medium inlet 50, the cooling medium inlet 50 is used for conveying a cooling medium into the mixing section 30, the mixing section 30 is used for mixing the feed liquid and the cooling medium, cooling the feed liquid and enabling the feed liquid to generate supersaturation and precipitate crystals, and the crystal growth section 40 is used for crystal growth and obtaining a suspension containing solute particles; the other end of the flow channel is also provided with a discharge port 60, and the discharge port 60 is used for continuously discharging the suspension out of the flow channel.
The fluid channel is an internal cavity surrounded by a round pipe, the upper end of the round pipe is a feed inlet 10, the lower end of the round pipe is a discharge outlet 60, the inner diameter of the round pipe is 12mm, the height of the round pipe is 260mm, the height-diameter ratio of the crystallization equipment is 21.7, the number of the cooling medium inlets 50 is 4, the cooling medium inlets are uniformly distributed on the side wall of the round pipe, the structure of the cooling medium inlet is a non-annular gap with the length of 5mm and the width of 2mm, and the distance from the central line of the non-annular gap to the discharge outlet 60 is 200mm (as shown in fig. 4).
The crystallization equipment is further provided with a buffer chamber 70, the buffer chamber 70 is annularly arranged outside the cooling medium inlet 50 and is completely attached to the equipment main body, the buffer chamber 70 is further provided with a cooling medium main inlet 71, the cooling medium main inlet 71 is used for continuously introducing cooling medium into the buffer chamber 70, and the buffer chamber 70 is used for storing the cooling medium and uniformly providing the cooling medium to the cooling medium inlet 50.
(2) Crystallization method
The crystallization method using the crystallization apparatus shown in fig. 9 comprises the following steps:
feed liquid consisting of solute and solvent I continuously enters the fluid channel through the feed inlet 10, and cooling medium continuously entering from the cooling medium inlet 50 is mixed with the feed liquid in the mixing section 30, cooled and generates supersaturation, so that crystals are precipitated;
the crystal continues to grow in the crystal growth section 40 and a suspension containing solute particles is obtained, which is continuously withdrawn from the flow channel through the discharge port 60.
Wherein, the feed liquid entering from the feed inlet 10 is a potassium nitrate aqueous solution (i.e. the solute is potassium nitrate, and the solvent I is water) at 40 ℃, the concentration of potassium nitrate in the feed liquid is 450g/L, the flow rate of the feed liquid is 150L/h, and the corresponding flow rate is 0.37 m/s; the cooling medium is dichloromethane with the temperature of minus 15 ℃, the cooling medium enters the buffer chamber 70 through the cooling medium total inlet 71 and enters the mixing section 30 through the cooling medium inlet 50, the total flow rate of the cooling medium entering the mixing section 30 is 500L/h, and the flow rate of the cooling medium in each cooling medium inlet 50 is 3.47 m/s; the ratio of the flow rate of the cooling medium entering through the cooling medium inlet 50 to the flow rate of the feed liquid entering through the feed inlet 10 is 9.4; the residence time of the feed liquid and the cooling medium in the mixing section 30 is 15 milliseconds; the residence time of the feed liquid in the flow channel was 87 milliseconds.
Sampling after the flow control of the crystallization equipment is stable, and filtering to obtain potassium nitrate crystals.
Effect data: the particle size distribution is 2-80 μm, and the volume median diameter d is determined by Malvern particle size analyzer0.5＝34μm。
Example 3
As shown in fig. 5, the crystallization apparatus has an apparatus main body, the apparatus main body has a fluid channel, one end of the fluid channel is provided with a feed inlet 10, the feed inlet 10 is used for continuously feeding a feed liquid containing solute and solvent I into the fluid channel, the fluid channel is sequentially divided into a conveying section 20, a mixing section 30 and a crystal growth section 40 along the flow direction of the feed liquid, the conveying section 20 is used for conveying the feed liquid to the mixing section 30, the side wall of the mixing section 30 at the end far away from the crystal growth section 40 is further provided with a cooling medium inlet 50, the cooling medium inlet 50 is used for conveying a cooling medium into the mixing section 30, the mixing section 30 is used for mixing the feed liquid and the cooling medium, cooling the feed liquid and enabling the feed liquid to generate supersaturation and precipitate crystals, and the crystal growth section 40 is used for crystal growth and obtaining a suspension containing solute particles; the other end of the flow channel is also provided with a discharge port 60, and the discharge port 60 is used for continuously discharging the suspension out of the flow channel.
Wherein, fluid passage is the inside cavity that a pipe encloses, and the upper end of pipe is feed inlet 10, and the lower extreme of pipe is discharge gate 60, and the internal diameter of pipe is 20mm, and the height of pipe is 350mm, and the height-diameter ratio of crystallization equipment is 17.5, and the equipartition has 6 high pressure nozzle that the inlet diameter is 6mm, nozzle diameter is 3mm on the lateral wall of pipe, and the distance of high pressure nozzle's central line apart from discharge gate 60 is 300mm (as shown in figure 6).
The crystallization equipment is further provided with a buffer chamber 70, the buffer chamber 70 is annularly arranged outside the cooling medium inlet 50 and is completely attached to the equipment main body, the buffer chamber 70 is further provided with a cooling medium main inlet 71, the cooling medium main inlet 71 is used for continuously introducing cooling medium into the buffer chamber 70, and the buffer chamber 70 is used for storing the cooling medium and uniformly providing the cooling medium to the cooling medium inlet 50.
(2) Crystallization method
The crystallization method using the crystallization apparatus shown in fig. 9 comprises the following steps:
feed liquid consisting of solute and solvent I continuously enters the fluid channel through the feed inlet 10, and cooling medium continuously entering from the cooling medium inlet 50 is mixed with the feed liquid in the mixing section 30, cooled and generates supersaturation, so that crystals are precipitated;
the crystal continues to grow in the crystal growth section 40 and a suspension containing solute particles is obtained, which is continuously withdrawn from the flow channel through the discharge port 60.
Wherein, the feed liquid entering from the feed inlet 10 is a 70 ℃ pentaerythritol aqueous solution (i.e., the solute is pentaerythritol, and the solvent I is water), the concentration of pentaerythritol in the feed liquid is 250g/L, the flow rate of the feed liquid is 250L/h, and the corresponding flow rate is 0.44 m/s; the cooling medium is petroleum ether with the temperature of-15 ℃, the cooling medium enters the buffer chamber 70 through the cooling medium total inlet 71 and enters the mixing section 30 through the cooling medium inlet 50, the total flow rate of the cooling medium entering the mixing section 30 is 500L/h, and the flow rate of the cooling medium in each cooling medium inlet 50 is 3.27 m/s; the ratio of the flow rate of the cooling medium entering through the cooling medium inlet 50 to the flow rate of the feed liquid entering through the feed inlet 10 is 7.4; the residence time of the feed liquid and the cooling medium in the mixing section 30 is 23 milliseconds; the residence time of the feed liquid in the flow channel was 452 milliseconds.
Sampling after the flow control of the crystallization equipment is stable, and filtering to obtain pentaerythritol crystals.
Effect data: measured by Malvern particle size analyzer, the particle size distribution is 8-100 μm, and the volume median diameter d0.5＝42μm。
Example 4
As shown in fig. 7, the crystallization apparatus has an apparatus main body, the apparatus main body has a fluid channel, one end of the fluid channel is provided with a feed inlet 10, the feed inlet 10 is used for continuously feeding a feed liquid containing solute and solvent I into the fluid channel, the fluid channel is sequentially divided into a conveying section 20, a mixing section 30 and a crystal growth section 40 along the flow direction of the feed liquid, the conveying section 20 is used for conveying the feed liquid to the mixing section 30, the side wall of the mixing section 30 at the end far away from the crystal growth section 40 is further provided with a cooling medium inlet 50, the cooling medium inlet 50 is used for conveying a cooling medium into the mixing section 30, the mixing section 30 is used for mixing the feed liquid and the cooling medium, cooling the feed liquid and enabling the feed liquid to generate supersaturation and precipitate crystals, and the crystal growth section 40 is used for crystal growth and obtaining a suspension containing solute particles; the other end of the flow channel is also provided with a discharge port 60, and the discharge port 60 is used for continuously discharging the suspension out of the flow channel.
The fluid channel is an internal cavity surrounded by a circular tube, the upper end of the circular tube is a feed inlet 10, the lower end of the circular tube is a discharge outlet 60, the inner diameter of the circular tube is 10mm, the height of the circular tube is 350mm, the height-diameter ratio of the crystallization device is 35, the cooling medium inlet 50 is an annular gap with the height of 3mm, and the distance from the center line of the annular gap to the discharge outlet 60 is 300mm (as shown in fig. 8).
The crystallization equipment is further provided with a buffer chamber 70, the buffer chamber 70 is annularly arranged outside the cooling medium inlet 50 and is completely attached to the equipment main body, the buffer chamber 70 is further provided with a cooling medium main inlet 71, the cooling medium main inlet 71 is used for continuously introducing cooling medium into the buffer chamber 70, and the buffer chamber 70 is used for storing the cooling medium and uniformly providing the cooling medium to the cooling medium inlet 50.
(2) Crystallization method
The crystallization method using the crystallization apparatus shown in fig. 9 comprises the following steps:
feed liquid consisting of solute and solvent I continuously enters the fluid channel through the feed inlet 10, and cooling medium continuously entering from the cooling medium inlet 50 is mixed with the feed liquid in the mixing section 30, cooled and generates supersaturation, so that crystals are precipitated;
the crystal continues to grow in the crystal growth section 40 and a suspension containing solute particles is obtained, which is continuously withdrawn from the flow channel through the discharge port 60.
Wherein, the feed liquid entering from the feed inlet 10 is a glycine aqueous solution (namely, the solute is glycine, the solvent I is water) at 60 ℃, the concentration of the glycine in the feed liquid is 400g/L, the flow rate of the feed liquid is 150L/h, and the corresponding flow rate is 0.53 m/s; the cooling medium is kerosene with the temperature of minus 5 ℃, the cooling medium enters the buffer chamber 70 through the cooling medium total inlet 71 and enters the mixing section 30 through the cooling medium inlet 50, the total flow of the cooling medium entering the mixing section 30 is 500L/h, and the flow speed of the cooling medium in each cooling medium inlet 50 is 1.47 m/s; the ratio of the flow rate of the cooling medium entering through the cooling medium inlet 50 to the flow rate of the feed liquid entering through the feed inlet 10 is 2.8; the residence time of the feed liquid and the cooling medium in the mixing section 30 is 15 milliseconds; the residence time of the feed liquid in the flow channel was 130 milliseconds.
Sampling after the flow control of the crystallization equipment is stable, and filtering to obtain glycine crystals.
Effect data: the particle size distribution is 2-76 μm, and the volume median diameter d is determined by Malvern particle size analyzer0.5＝50μm。
Claims (13)
1. The utility model provides a crystallization equipment, its characterized in that, crystallization equipment has the equipment main part, the equipment main part has at least one fluid passage, fluid passage's one end is equipped with the feed inlet, the feed inlet is used for sending into in succession the feed liquid that contains solute and solvent I in the fluid passage, fluid passage follows the flow direction of feed liquid divide into in proper order and carries section, mixing section and crystal growth section, carry the section be used for with the feed liquid carry to mixing section, mixing section is kept away from the lateral wall of the one end of crystal growth section still is equipped with the cooling medium entry, the cooling medium entry is used for sending into cooling medium mixing section, mixing section is used for realizing the feed liquid with cooling medium's mixture, the cooling of feed liquid and feasible produce the supersaturation and separate out the crystal, crystal growth section is used for the growth of crystal, And obtaining a suspension containing solute particles; the other end of the fluid channel is also provided with a discharge hole, and the discharge hole is used for continuously discharging the suspension out of the fluid channel;
the fluid channel is an internal cavity surrounded by a round pipe, the upper end of the round pipe is the feed inlet, the lower end of the round pipe is the discharge outlet, and the cooling medium inlet is arranged on the side wall of the round pipe;
the structure of the cooling medium inlet is one or more of a circular hole, a non-annular gap and a high-pressure nozzle.
2. The crystallization apparatus as claimed in claim 1, wherein the mixing section is provided with more than two cooling medium inlets, and the cooling medium inlets are uniformly distributed on the side wall of the mixing section.
3. The crystallization apparatus as claimed in claim 1 or 2, wherein the cooling medium inlet is configured as an annular gap.
4. The crystallization apparatus as claimed in claim 3, wherein the annular gap has a height of 0.1mm to 10 mm.
5. The crystallization apparatus according to claim 1 or 2, wherein the crystallization apparatus is further provided with a buffer chamber, the buffer chamber is arranged around the cooling medium inlet and is completely attached to the apparatus main body, the buffer chamber is further provided with a cooling medium inlet, the cooling medium inlet is used for continuously introducing a cooling medium into the buffer chamber, and the buffer chamber is used for storing the cooling medium and uniformly supplying the cooling medium to the cooling medium inlet;
and/or the crystal growth section is provided with fins and/or baffles, and the fins and/or the baffles are used for enhancing the micro-mixing effect of the crystal growth section.
6. A crystallization method using the crystallization apparatus according to any one of claims 1 to 5, characterized in that the crystallization method comprises the steps of:
feed liquid containing solute and solvent I continuously enters the fluid channel through the feed inlet, and cooling medium continuously entering from the cooling medium inlet is mixed with the feed liquid in the mixing section, cooled and supersaturated, so that crystals are precipitated;
and the crystal continues to grow in the crystal growth section, and a suspension containing solute particles is obtained, and the suspension is continuously discharged out of the fluid channel from the discharge port.
7. The crystallization method according to claim 6, wherein the cooling medium is the solvent I and/or a solvent II immiscible with the solvent I.
8. The crystallization method according to claim 6, wherein a ratio of a flow rate of the cooling medium entering through the cooling medium inlet to a flow rate of the feed liquid entering through the feed port is 1 or more.
9. The crystallization method according to claim 8, wherein a ratio of a flow rate of the cooling medium entering through the cooling medium inlet to a flow rate of the feed liquid entering through the feed port is 2 to 10.
10. The crystallization method according to claim 6, wherein the residence time of the feed liquid and the cooling medium in the mixing section is not more than 100 milliseconds;
and/or the residence time of the feed liquid in the fluid channel is not more than 10 seconds.
11. The crystallization method according to claim 10, wherein the residence time of the feed liquid and the cooling medium in the mixing section is not more than 20 milliseconds.
12. The crystallization method according to claim 11, wherein the residence time of the feed liquid and the cooling medium in the mixing section is not more than 10 milliseconds.
13. The crystallization method according to claim 6, wherein the suspension is filtered and dried to obtain a powder product of solute particles.
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