Static melt crystallization system and static melt crystallization method

Abstract

The invention relates to a static melt crystallization system and a static melt crystallization method. The static melt crystallization system comprises a static melt crystallizer, a gas conveying structure and a bubbling mechanism, the static melt crystallizer comprises a shell and a first heat exchange mechanism, the bubbling mechanism comprises a bubbling pipe, one end of the bubbling pipe is connected with the gas conveying mechanism, and the other end of the bubbling pipe is communicated with the interior of the shell. The gas conveying structure and the bubbling mechanism are additionally arranged, the bubbling mechanism is arranged to comprise the bubbling pipe, one end of the bubbling pipe is connected with the gas conveying mechanism, the other end of the bubbling pipe is communicated with the interior of the shell, and auxiliary gas such as nitrogen can be introduced into the bubbling pipe through the gas conveying mechanism; the bubbling mechanism enables the auxiliary gas to form bubbles, and in the material crystallization process, the bubbles enter the vicinity of the crystallization plate and disturb the material to accelerate the formation of a crystallization core, so that the nucleation of the material is accelerated, the crystallization time is shortened, the crystallization efficiency is improved, the energy consumption is reduced, and the purity of a finished product is improved.

Description

Technical Field

[0001] The present application relates to the field of chemical technology, and in particular to a static melt crystallization system and a static melt crystallization method. Background Art

[0002] Melt crystallization technology is an important separation, purification and concentration technology. This technology uses the difference in the melting point of the mixture to separate different substances by crystallization. Melt crystallization can be divided into two processes: crystallization and sweating. The crystallization process is the process in which crystals are precipitated in the melt under the impetus of supersaturation or supercooling. Sweating is a post-processing process to improve the purity of crude crystals. Crystals with many impurities have a low melting point. By heating up in steps, these crystals are melted and discharged first, achieving the purpose of purifying crude crystals. Melt crystallization technology has the advantages of being environmentally friendly, not requiring other solvents, low operating temperature, high efficiency, low energy consumption, and a wide range of applications. It is widely used in the refining and purification of chemical intermediates, pharmaceutical intermediates, and biochemical products.

[0003] Static melt crystallizer is a device used in static melt crystallization process. During the crystallization process, the temperature of the shell side heat exchange medium is gradually reduced to gradually cool down and crystallize the molten material in the tube side. After the crystallization is completed, the unsolidified low-concentration residual liquid is discharged, and then the temperature of the coarse crystals in the tube side is slowly increased by the shell side medium to make them "sweat" and further purified. Usually, the static melt crystallizer contains a number of parallel cooling plates or tube bundles. The hot and cold media circulate inside the plates, and the raw material liquid in a molten static state accumulates outside the plates. Since the material is in a static state, it is difficult to form a crystallization core, which not only prolongs the crystallization time, but also reduces the crystallization efficiency, resulting in a long crystallization time, high energy consumption, and low product purity.

[0004] In summary, the existing static melt crystallizer has the defects of low crystallization efficiency, long crystallization time, high energy consumption and low product purity during the production process. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a static melt crystallization system and a static melt crystallization method to solve the above-mentioned defects such as low crystallization efficiency, long crystallization time, high energy consumption, and low product purity.

[0006] To achieve the above objectives, the scheme of this application is as follows:

[0007] In a first aspect, the present invention provides a static melt crystallization system, which includes a static melt crystallizer, a gas delivery structure and a bubbling mechanism. The static melt crystallizer includes a shell and a first heat exchange mechanism. The bubbling mechanism includes a bubbling tube, one end of the bubbling tube is connected to the gas delivery mechanism, and the other end is connected to the interior of the shell, and is used to bubble bubbles into the interior of the material to be purified in the shell. The first heat exchange mechanism is used to control the temperature of the material to be purified.

[0008] Optionally, the static melt crystallization system further comprises a second heat exchange mechanism, which is used to control the gas temperature so that it is consistent with the material temperature or lower than the temperature of the material to be purified (ie, the auxiliary gas is supercooled).

[0009] Optionally, the static melt crystallizer also includes a plurality of crystallization plates arranged vertically inside the shell, and the bubbling mechanism also includes a bubble distribution network, the bubble distribution network is located in the shell, the bubble distribution network includes a main pipe and a plurality of branch pipes connected to the main pipe, the main pipe is connected to the bubbling pipe, and the plurality of branch pipes are evenly distributed between the crystallization plates.

[0010] Optionally, the main pipe and / or the branch pipe of the static melt crystallizer is provided with a plurality of bubbling ports, and each of the bubbling ports is provided with a one-way valve.

[0011] In a second aspect, the present invention further provides a static melt crystallization method, the static melt crystallization method comprising the following steps:

[0012] During the crystallization process of the material to be purified, auxiliary gas is blown into the material to be purified in the form of bubbles to disturb the material to be purified.

[0013] Optionally, the static melt crystallization method uses the static melt crystallization system as described above to perform static melt crystallization, and the static melt crystallization method comprises the following steps:

[0014] During the crystallization process of the material to be purified, the temperature of the material to be purified is controlled by the first heat exchange mechanism, the auxiliary gas is fed into the bubbling tube by the gas delivery mechanism, and the auxiliary gas is bubbled into the material to be purified in the form of bubbles through the bubbling tube to disturb the material to be purified.

[0015] Optionally, the auxiliary gas is selected from at least one of nitrogen, helium, argon and neon.

[0016] Optionally, the pressure of the auxiliary gas is 0.1-0.5 MPa, preferably 0.15-0.5 MPa.

[0017] Optionally, the flow rate of the auxiliary gas is 0.05-1.5 L / min, preferably 0.1-1.5 L / min.

[0018] Optionally, during the crystallization process, the cooling rate of the heat exchange medium used is 0.01-5°C / min, preferably 0.02-5°C / min.

[0019] As described above, the static melt crystallization system and static melt crystallization method of the present application have the following beneficial effects:

[0020] The present application delivers nitrogen auxiliary gas in the form of bubbles into a static melt crystallizer during the melt crystallization process, so that the auxiliary gas can disturb the material to be purified, accelerate the formation of crystallization cores, and then promote the material to accelerate nucleation, shorten the crystallization time, improve the crystallization efficiency, reduce energy consumption, and improve the purity of the finished product. The disturbing effect of the bubbles can reduce the possibility of impurities entrained in the crystals formed during the melt crystallization process, thereby further improving the purity of the finished product. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0022] Figure 1 It is a schematic structural diagram of the static melt crystallization system of Example 1;

[0023] Figure 2 for Figure 1 Schematic cross-section of a static melt crystallizer (AA direction);

[0024] Figure 3 for Figure 1 Schematic diagram of the cross section of the bubble distribution test tube (BB direction);

[0025] Figure 4 for Figure 3 Schematic cross-sectional view of the middle bubble port (CC direction).

[0026] Figure 5 is a schematic structural diagram of the valve cover in Example 2;

[0027] Figure 6 It is a structural schematic diagram of the valve body in Example 2;

[0028] Figure 7 This is a schematic diagram of the structure of the valve body in Example 3;

[0029] Figure 8 Schematic diagram of the structure of the static melt crystallization system of Example 4.

[0030] Reference numerals

[0031] 1- one-way valve, 11- valve cover, 111- first rack, 12- valve body, 121- second rack, 1211- baffle;

[0032] 2-shell, 21-material inlet, 22-second heat transfer medium inlet, 23-auxiliary gas inlet, 24-heat transfer medium outlet, 25-supercooling liquid inlet, 26-supercooling liquid outlet, 27-material outlet, 28-first heat transfer medium inlet, 29-first heat transfer medium outlet;

[0033] 3- Crystallization plate;

[0034] 4-bubble tube;

[0035] 5- Jacket;

[0036] 6- sight glass;

[0037] 71-main pipe, 72-first branch pipe, 73-second branch pipe, 74-bubble port. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, top, bottom...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0040] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text is to include three parallel solutions. Taking "A and / or B as an example", it includes solution A, or solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0042] An embodiment of the present invention provides a static melt crystallization system, including a static melt crystallizer, a gas delivery structure and a bubbling mechanism, the static melt crystallizer includes a shell 2 and a first heat exchange mechanism, the bubbling mechanism includes a bubbling tube 4, one end of the bubbling tube 4 is connected to the gas delivery mechanism, and the other end is connected to the inside of the shell 2, which is used to bubble bubbles into the inside of the material to be purified in the shell 2, and the first heat exchange mechanism is used to control the temperature of the material to be purified. The static melt crystallizer also includes a plurality of crystallization plates 3 vertically arranged inside the shell 2, the bubbling mechanism also includes a bubble distribution network, the bubble distribution network is located in the shell 2, the bubble distribution network includes a main pipe 71 and a plurality of level branches 72 connected to the main pipe 71, the main pipe 71 is connected to the bubbling tube 4, and the plurality of level branches 72 are evenly distributed between the crystallization plates 3, the main pipe 71 and / or the branch pipe 72 are provided with a plurality of bubbling ports 73, and each bubbling port 73 is provided with a one-way valve 1.

[0043] In another embodiment of the present invention, the static melt crystallization system further comprises a second heat exchange mechanism, which is used to control the gas temperature so that it is consistent with or lower than the temperature of the material to be purified (ie, the auxiliary gas is supercooled).

[0044] An embodiment of the present invention further provides a static melt crystallization method, which uses the static melt crystallization system as described above to perform static melt crystallization. The static melt crystallization method comprises the following steps:

[0045] During the crystallization process of the material to be purified, the temperature of the material to be purified is controlled by the first heat exchange mechanism, and an auxiliary gas is fed into the bubbling tube by the gas delivery mechanism. The auxiliary gas is bubbled into the material to be purified through the bubbling tube in the form of bubbles to disturb the material to be purified. The auxiliary gas is selected from at least one of nitrogen, helium, argon and neon. The pressure of the auxiliary gas is 0.1-0.5MPa, and the flow rate of the auxiliary gas is 0.05-1.5L / min. During the crystallization process, the cooling rate of the heat exchange medium used is 0.01-5℃ / min, preferably 0.02-5℃ / min.

[0046] In the following description, numerous details are discussed to provide a more thorough explanation of embodiments of the present invention; however, it is apparent to one skilled in the art that embodiments of the present invention may be practiced without these specific details.

[0047] Example 1

[0048] See also Figures 1 to 6 , Figures 1 to 6 This is a structural schematic diagram of the static melt crystallization system of this embodiment, which includes a static melt crystallizer, a gas delivery structure and a bubbling mechanism. The gas delivery structure is used to deliver auxiliary gases such as nitrogen into the static melt crystallizer, and the static bubbling mechanism includes a bubbling tube 4 and a bubble distribution network.

[0049] Please continue reading Figures 1 to 4The static crystallizer includes a shell 2. The top of the shell 12 is provided with a material inlet 21, a first heat transfer medium inlet 22, an auxiliary gas inlet 23, a second heat transfer medium inlet 28, a first heat transfer medium outlet 24, a second heat transfer medium outlet 29, a supercooling liquid inlet 25 and a supercooling liquid outlet 26. The bottom of the shell 2 is provided with a material outlet 26. A flow regulating valve (not shown) and a temperature regulating component (not shown) are provided at the first heat transfer medium inlet 22 and the second heat transfer medium inlet 28. A heat transfer medium distributor (not shown) is provided between the first heat transfer medium inlet 22 and the crystallization plate 3. The material inlet 21, the first heat transfer medium inlet 22, the auxiliary gas inlet 23, the supercooled liquid inlet 25 and the second heat transfer medium inlet 28 are respectively used as inlets for the material to be purified, the first heat transfer medium, the auxiliary gas, the supercooled liquid and the second heat transfer medium to enter the shell 2. The second heat transfer medium outlet 24, the material outlet 27, the supercooled liquid outlet 26 and the second heat transfer medium outlet 29 are respectively used as outlets for the heat transfer medium, the purified material, the supercooled liquid and the second heat transfer medium to be discharged from the shell 2. The first heat transfer medium inlet 22 and the first heat transfer medium outlet 24 are connected to a first heat transfer medium storage container (not shown) to form a first heat exchange mechanism. The first heat exchange mechanism is used to control the temperature of the material to be purified. The temperature of the material to be purified is controlled by heat exchange between the first heat transfer medium and the material to be purified. A sight glass 6 for observing the state of the material is provided on the upper side of the housing 2 .

[0050] Please continue reading Figures 1 to 4, a plurality of crystallization plates 3 are arranged between the material inlet 21 and the material outlet 26, all of the crystallization plates 3 are arranged in parallel along the vertical direction, the crystallization plates 3 are connected to the first heat transfer medium inlet 22 and the first heat transfer medium outlet 24, the auxiliary gas inlet 23 is connected to the bubbling tube 4, the bubbling tube 4 and the bubble distribution pipe network are both covered with a jacket 5, the jacket 5 is provided with a jacket inlet and a jacket outlet, the jacket inlet is connected to the second heat transfer medium inlet 28 and the supercooled liquid inlet 25, and the jacket outlet 29 is connected to the second heat transfer medium outlet 29 and the supercooled liquid outlet 26. The second heat transfer medium inlet 28 and the second heat transfer medium outlet 29 are connected to the second heat transfer medium storage container (not shown), and the supercooled liquid inlet 25 and the supercooled liquid outlet 26 are connected to the supercooled liquid storage container (not shown), so as to form a second heat exchange mechanism, and the second heat exchange mechanism controls the temperature of the auxiliary gas through heat exchange between the second heat transfer medium, the supercooled liquid and the auxiliary gas, so that the temperature of the auxiliary gas is consistent with the temperature of the material to be purified or lower than the temperature of the material to be purified (that is, the auxiliary gas is supercooled). One end of the bubbling tube 4 is connected to the gas delivery mechanism, and the other end is connected to the inside of the shell 2, and is used to bubble bubbles into the material to be purified in the shell 2. The bubble distribution pipe network includes a main pipe 71 and a plurality of branch pipes 72 connected to the main pipe 71, the main pipe 71 is connected to the bubbling tube 4, and the plurality of branch pipes 72 are evenly distributed between the crystallization plates 3. The main pipe 71 and / or the branch pipe 72 are provided with a plurality of bubbling ports, and each bubbling port is provided with a one-way valve 1. The bubble distribution network is located in the shell 2, and the bubble distribution network includes a main pipe 71 and several level branches connected to the main pipe. The main pipe 71 is connected to the bubbling pipe 4, and the several level branches 72 are evenly distributed between the crystallization plates 3. The several level branches include several primary branches 72 and several secondary branches 73. The main pipe 71 is connected to several primary branches 72 arranged vertically or horizontally, and each primary branch 72 is connected to several secondary branches 73 arranged vertically or horizontally. The main pipe 71 and / or the primary branch 72 and / or the secondary branch 73 are provided with several bubbling ports 74, and each bubbling port 74 is provided with a one-way valve 1. The bubbling port is arranged horizontally or obliquely. Preferably, the angle between the bubbling port 74 and the crystallization plate 3 is 45-90°. The one-way valve is a prior art and will not be described here.

[0051] Specifically, this embodiment can prevent the material from being sucked back into the bubbling tube by adding a one-way valve at the bubbling port 74, while avoiding the risk of crystallization blockage in the bubbling tube 4. This embodiment can introduce bubbles formed by auxiliary gases such as nitrogen into the plate around the crystallization plate 3 by setting the bubbling port 74 horizontally or obliquely, especially setting the angle between the bubbling port 74 and the crystallization plate 3 to 45-90°, which is more conducive to the material forming crystals on the plate of the crystallization plate 3, promoting the growth of crystals along the plate, and further shortening the crystallization time, improving the crystallization efficiency, reducing energy consumption, and improving the purity of the finished product. The possibility of impurities entrained in the crystals formed during the melt crystallization process is reduced by the disturbing effect of the bubbles, and the purity of the finished product is further improved. This embodiment is convenient for observing the state of the material through the mirror 6 by adding a sight glass 6 for observing the state of the material on the upper side of the shell 2, and then adjusting the flow of the auxiliary gas according to the observed state of the material. This embodiment can control the temperature of the auxiliary gas by adding a second heat exchange mechanism, so that it is consistent with the temperature of the material to be purified or lower than the temperature of the material to be purified (even if the auxiliary gas is supercooled). Then, during the crystallization process, the gas bubbling is used to disturb the airflow of the material to accelerate crystal nucleation, or the supercooling degree is increased by the supercooled gas and the supercooled heat-conducting medium in the jacket of the bubbling pipe to promote the nucleation of crystals near the bubbling pipe, thereby accelerating crystal growth, shortening the crystallization time, and reducing energy consumption.

[0052] Example 2

[0053] See also Figure 5 and Figure 6 The difference between this embodiment and embodiment 1 is that the one-way valve includes a valve body 12 and a valve cover 11 hinged to the valve body 12, a valve core (not shown) is arranged in the valve body 12, and an inlet end and an outlet end are respectively arranged at both ends of the valve body 12.

[0054] See also Figure 5 and Figure 6 The outlet end of the valve body 12 is provided with a valve cover 11, one side of the valve cover 11 is hinged to the valve body 12, a local area of ​​the valve cover 11 is provided with a plurality of first racks 111 arranged in parallel, the local area is located on the opposite side of the hinged corresponding side of the valve cover 11, and the valve body 12 is provided with a second rack 121 matched with the first rack 111. Along the direction from the middle to the two sides, the tooth pitch of two adjacent first racks 111 gradually increases.

[0055] Specifically, in this embodiment, a hinged valve body 12 and a valve cover 11 are provided, and a second rack 112 and a first rack 111 that mesh with each other are respectively provided on the valve body 12 and the valve cover 11. When the one-way valve 1 is opened, a gap is formed between the second rack 112 and the first rack 111, and the valve body can be sealed by the mutual cooperation of the second rack 112 and the first rack 111. At this time, a small gap is formed between the first rack and the second rack, and the gas overflows from the gap. The gap between the racks assists the gas to form bubbles that are further reduced, forming more tiny bubbles, and the number and dispersion of the bubbles increase. The so-called dispersion means that for bubbles of the same volume, the volume of a single bubble becomes smaller due to the increase in the number, and its actual coverage range is larger, thereby shortening the crystallization time, improving the crystallization efficiency, reducing energy consumption, and improving the purity of the finished product. In the direction from the middle to the two sides, this embodiment sets the pitch of the two adjacent first racks 111 to gradually increase, so that when the airflow hits the valve cover, the gap between the first rack 111 and the second rack 112 on the corresponding side can be reduced, so that the bubbles formed by the auxiliary gas become smaller, and more bubbles are formed, the number and density of bubbles are increased, and the disturbance effect on the material is enhanced, thereby shortening the crystallization time, improving the crystallization efficiency, reducing energy consumption, and improving the purity of the finished product. At the same time, the reciprocating motion of the valve cover 12 during the repeated opening and closing process can scrape off the crystals to prevent the crystals from clogging the one-way valve.

[0056] Example 3

[0057] See also Figure 7 The difference between this embodiment and the embodiment is that a baffle 1211 is provided at the inner edge of the second rack 121 located on at least one of the two sides, and a gap is left between the baffle 1211 and the adjacent second rack 121, that is, a gap is left between the baffle 1211 and the adjacent second rack 121 provided with the baffle.

[0058] In this embodiment, a baffle 1211 is added to the side wall edge of the second rack 112 located on at least one of the two sides. The baffle 1211 can resist the airflow, reduce the airflow passing through the second rack 112 located on the corresponding side, shrink the bubbles here, promote the formation of more tiny bubbles, increase the number and density of bubbles, enhance the disturbance effect on the material, thereby shortening the crystallization time, improving the crystallization efficiency, reducing energy consumption, and improving the purity of the finished product.

[0059] Example 4

[0060] See also Figure 8 The difference between this embodiment and embodiment 1 is that the bubbling tube 4 and the bubble distribution official website are not covered with a jacket 5.

[0061] Example 5

[0062] The static melt crystallization system of Example 3 is used to purify the material m-phenylenediamine to be purified, and the specific steps are as follows:

[0063] The material to be purified is fed into the shell 2 of the static melt crystallizer with an effective operating volume of 12L through the material inlet (the volume of the material is 80% of the effective operating volume of the static melt crystallizer). When the amount of the material to be purified reaches a certain level, it enters the crystallization plate 3. The first heat-conducting medium inlet 22 is used to distribute the hot water with a temperature of 71°C through the heat-conducting medium distributor and then enters the crystallization plate 3. The first heat-conducting medium is controlled to cool at a cooling rate of 0.04°C / min. The first heat-conducting medium is discharged from the first heat-conducting medium outlet 24 after heat exchange with the material. In this process In the process, nitrogen gas with a pressure of 0.2 MPa and a flow rate of 1 L / min is introduced into the bubbling tube 4 through the air inlet as a process gas. The nitrogen gas forms bubbles after passing through the several stages of distribution pipes 41 and the one-way valve 1 at the bubbling port 411. These bubbles enter the vicinity of the crystallization plate and disturb the material in a static state, accelerate the formation of crystallization cores, and then promote the material to accelerate nucleation, shorten the crystallization time, improve the crystallization efficiency, reduce energy consumption, and improve the purity of the finished product. The disturbing effect of the bubbles reduces the possibility of impurities entrained in the crystals formed during the melt crystallization process, and further improves the purity of the finished product;

[0064] At the beginning of the crystallization process, the jacket inlet is connected to the second heat transfer medium inlet 28, and the jacket outlet is connected to the second heat transfer medium outlet 29. The second heat transfer medium in the jacket 5 is hot water with a temperature of 71°C and the first heat transfer medium in the crystallization plate 3 is cooled synchronously;

[0065] During the cooling crystallization process, when the temperature of the second heat transfer medium reaches 61°C, the inlet of the jacket 5 is switched to be connected to the inlet of the supercooling liquid, and water with a supercooling liquid temperature of 32°C is introduced until crystals appear. The supercooling liquid is discharged from the supercooling liquid outlet after heat exchange with the material;

[0066] After the crystal appears, the jacket inlet is switched to be connected to the second heat transfer medium inlet 28, and the jacket outlet is connected to the second heat transfer medium outlet 29, so that the second heat transfer medium in the jacket 5 and the first heat transfer medium in the crystallization plate 3 are cooled synchronously;

[0067] When the second heat transfer medium is cooled to the final crystallization temperature of 52° C. and maintained at a constant temperature for 1 hour, the crystallization is completed, and the introduction of nitrogen into the bubbling tube 41 is stopped, and the mother liquid is discharged;

[0068] The temperature is continued to be raised to sweat, and the temperature is raised to the final sweating temperature of 61°C at a heating rate of 0.04°C / min to discharge sweat; the temperature is continued to be raised to melt, and the obtained crystallized product is discharged from the material outlet 26.

[0069] Example 6

[0070] The difference between this embodiment and embodiment 5 is that the material to be purified is ethylene carbonate, the first heat transfer medium and the second heat transfer medium are both hot water with a temperature of 47°C, when the temperature of the second heat transfer medium reaches 37°C, the inlet of jacket 5 is switched to be connected to the inlet of supercooling liquid, the supercooling liquid is water with a temperature of 7°C, the final crystallization temperature is 28°C, and the final sweating temperature is 61°C.

[0071] Comparative Example 1

[0072] The difference between this comparative example and Example 5 is that nitrogen was not introduced.

[0073] Comparative Example 2

[0074] The difference between this comparative example and Example 5 is that the valve cover 11 is replaced by a screen.

[0075] During the cooling and crystallization process, crystals form on the screen, blocking the mesh of the screen and making it impossible to continue production.

[0076] Comparative Example 3

[0077] The difference between this comparative example and Example 6 is that nitrogen was not introduced.

[0078] Purity testing

[0079] According to "HG / T 3401-2014 Metaphenylenediamine", the raw materials and products used in Example 5 and the raw materials and finished products used in Comparative Example 1 were tested for purity, and the results are shown in Table 1;

[0080] Gas chromatography was used to test the purity of the raw materials and the obtained products used in Example 6 and the raw materials and the obtained finished products used in Comparative Example 3. The results are shown in Table 2.

[0081] Table 1 Purity test results

[0082] Group Purity of raw materials Purity of finished product Example 5 95.30％ 99.45％ Comparative Example 1 95.30％ 98.72％

[0083] Table 2 Purity test results

[0084] Group Purity of raw materials Purity of finished product Example 6 99.00％ 99.88％ Comparative Example 3 99.00％ 99.78％

[0085] As shown in Table 1, compared with Comparative Example 1 (nitrogen is not passed into the melt crystallization process), the purity of Example 5 (nitrogen is passed into the melt crystallization process) is significantly improved. As shown in Table 2, compared with Comparative Example 3 (nitrogen is not passed into the melt crystallization process), the purity of Example 6 (nitrogen is passed into the melt crystallization process) is significantly improved. The result shows that the application is by sending nitrogen auxiliary gas into a static melt crystallizer in the form of bubbles during the melt crystallization process, and the material to be purified can be disturbed by auxiliary gas, the formation of crystallization cores can be accelerated, and then the material is prompted to accelerate nucleation, shorten the crystallization time, improve crystallization efficiency, reduce energy consumption, improve finished product purity, and reduce the possibility of impurities in the crystals formed in the melt crystallization process by the disturbing effect of bubbles, and further improve the finished product purity.

[0086] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A static melt crystallization system, characterized in that: The static melt crystallization system includes a static melt crystallizer, a gas delivery structure and a bubbling mechanism. The static melt crystallizer includes a shell and a first heat exchange mechanism. The bubbling mechanism includes a bubbling tube. One end of the bubbling tube is connected to the gas delivery mechanism, and the other end is connected to the inside of the shell, and is used to bubble bubbles into the material to be purified in the shell. The first heat exchange mechanism is used to control the temperature of the material to be purified.

2. The static melt crystallization system according to claim 1, characterized in that The static melt crystallization system also includes a second heat exchange mechanism, which is used to control the gas temperature so that it is consistent with the material temperature or lower than the temperature of the material to be purified.

3. The static melt crystallization system according to claim 1, characterized in that The static melt crystallizer also includes a plurality of crystallization plates vertically arranged inside the shell, and the bubbling mechanism also includes a bubble distribution network, the bubble distribution network is located in the shell, the bubble distribution network includes a main pipe and a plurality of branch pipes connected to the main pipe, the main pipe is connected to the bubbling pipe, and the plurality of branch pipes are evenly distributed between the crystallization plates.

4. The static melt crystallization system according to claim 3, characterized in that: The main pipe and / or the branch pipe of the static melt crystallizer are provided with a plurality of bubbling ports, and each of the bubbling ports is provided with a one-way valve.

5. A static melt crystallization method, characterized in that: The static melt crystallization method comprises the following steps: During the crystallization process of the material to be purified, auxiliary gas is blown into the material to be purified in the form of bubbles to disturb the material to be purified.

6. The static melt crystallization method according to claim 5, characterized in that Static melt crystallization is performed using the static melt crystallization system according to any one of claims 1 to 4, wherein the static melt crystallization method comprises the following steps: During the crystallization process of the material to be purified, the temperature of the material to be purified is controlled by the first heat exchange mechanism, the auxiliary gas is fed into the bubbling tube by the gas delivery mechanism, and the auxiliary gas is bubbled into the material to be purified in the form of bubbles through the bubbling tube to disturb the material to be purified.

7. The static melt crystallization method according to claim 5, characterized in that The auxiliary gas is selected from at least one of nitrogen, helium, argon and neon.

8. The static melt crystallization method according to claim 5, characterized in that: The pressure of the auxiliary gas is 0.1-0.5 MPa.

9. The static melt crystallization method according to claim 5, characterized in that The flow rate of the auxiliary gas is 0.05-1.5 L / min.

10. The static melt crystallization method according to claim 5, characterized in that: During the crystallization process, the cooling rate of the heat exchange medium used is 0.01-5°C / min.

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