Multi-stage circulating cooling crystallization apparatus and cooling method thereof

Abstract

The application discloses a multistage circulating cooling crystallization device and a cooling method thereof, and relates to the field of cooling crystallization. The device comprises a heat exchange kettle, the inside of the heat exchange kettle is provided with a heat exchange interlayer, the top and bottom of the heat exchange kettle are respectively fixedly connected with a liquid inlet pipe and a crystal liquid discharge pipe, and the bottom of the crystal liquid discharge pipe is provided with a control valve. The multistage circulating cooling crystallization device and the cooling method thereof, through a circulating pump, can deliver low-temperature cooling liquid in a cooler to a three-stage kettle body, and after heat exchange with the internal solution, the heat-exchanged cooling liquid is sequentially introduced into a two-stage kettle body and a three-stage kettle body for heat exchange, so that the heat exchange of the cooling liquid is more sufficient, and the original liquid can be pre-cooled when entering the one-stage kettle body, so that the temperature when entering the two-stage kettle body is slightly lower, and after being cooled again in the two-stage kettle body, the temperature when entering the three-stage kettle body for cooling crystallization is lower, so that the crystallization effect is better.

Description

Technical Field

[0001] This invention relates to cooling crystallization technology, specifically to a multi-stage circulating cooling crystallization apparatus and its cooling method. Background Technology

[0002] Cooling crystallization is a common method for solute purification. By lowering the temperature of a hot saturated solution, the solute components in the solution can crystallize and precipitate out, thereby obtaining the desired crystalline substance.

[0003] Cooling crystallizers are commonly used solution crystallization devices. They achieve cooling crystallization by introducing cooling water into the jacket of a heat exchange vessel and exchanging heat between the jacket and the solution inside the vessel. Chinese invention patent application number 202311289349.7 discloses a multi-stage cooling crystallization device for the preparation of sodium triazole salt. This device consists of a primary cooling mechanism, a secondary crystallization mechanism, and a tertiary material preparation mechanism. The cooling medium passes through these mechanisms sequentially, allowing different temperatures to be applied at different stages of crystal precipitation, thus facilitating sufficient heat exchange. However, in practical applications, when the cooling medium enters the cooling jacket of the secondary crystallization mechanism, it enters from the bottom and exits from the top after filling the jacket. With continued supply of cooling medium, the medium diffuses at the bottom, increasing the amount of cooling medium there and raising the liquid level at the top, causing it to exit from the top outlet. During this process, the diffusion of the low-temperature cooling medium is slow, resulting in a lower temperature near the inlet and a higher temperature further up the jacket. This leads to a large surface temperature difference in the cooling jacket during heat exchange with the solution, which is detrimental to the solution cooling and crystallization process. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-stage circulating cooling crystallization apparatus and its cooling method to overcome the above-mentioned shortcomings in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a multi-stage circulating cooling crystallization device, comprising...

[0006] A heat exchange vessel is provided with a heat exchange jacket inside. The top and bottom of the heat exchange vessel are respectively fixedly connected to a liquid inlet pipe and a liquid outlet pipe. A control valve is provided at the bottom of the liquid outlet pipe. The bottom and top of the heat exchange vessel are respectively provided with a coolant inlet pipe and a coolant outlet pipe fixedly connected to the heat exchange jacket. A stirrer is provided inside the heat exchange vessel.

[0007] A heat equalization mechanism is installed inside the heat exchange vessel. The heat equalization mechanism includes a plurality of first rotating shafts and second rotating shafts that are equidistantly rotatably connected in a ring shape inside the heat exchange jacket. A plurality of flat stirring blades are fixedly connected at equal intervals from top to bottom on the outer surface of the first rotating shafts. A plurality of inclined stirring blades are fixedly connected at equal intervals from top to bottom on the outer surface of the second rotating shafts. The plurality of first rotating shafts and the plurality of second rotating shafts are arranged alternately in sequence. A driving assembly is provided between the first rotating shafts and the second rotating shafts. The driving assembly is used to drive the first rotating shafts and the second rotating shafts to rotate synchronously.

[0008] The heat exchange vessel includes a primary vessel body, a secondary vessel body, and a tertiary vessel body. The liquid discharge pipe located on the primary vessel body is fixedly connected to the liquid inlet pipe located on the secondary vessel body, and the liquid discharge pipe located on the secondary vessel body is fixedly connected to the liquid inlet pipe located on the tertiary vessel body.

[0009] The cooler has its inlet end fixedly connected to the coolant outlet pipe located on the primary reactor body;

[0010] A circulating pump, the inlet end of which is fixedly connected to the outlet end of the cooler, and the outlet end of the circulating pump is fixedly connected to the inlet pipe located on the three-stage reactor body.

[0011] Furthermore, the drive assembly includes a mounting box fixedly installed on the inner wall of the heat exchange jacket. An impeller is rotatably connected to the inner side of the mounting box. A flow channel is opened on the inner side of the mounting box. The flow channel is fixedly connected to the coolant inlet pipe. When the coolant discharged from the coolant inlet pipe passes through the flow channel and enters the interior of the heat exchange jacket, the coolant flows and drives the impeller to rotate.

[0012] Furthermore, the heat exchange vessel has an annular groove inside, and a first gear located inside the annular groove is coaxially fixedly connected to the outside of the impeller. The first rotating shaft and the second rotating shaft are respectively fixedly connected to a second gear located inside the annular groove. A gear ring is rotatably connected to the inner side of the annular groove.

[0013] Furthermore, both the first gear and several of the second gears mesh with the ring gear.

[0014] Furthermore, when the drive assembly drives the first and second rotating shafts to rotate, the first rotating shaft drives the flat plate stirring blades to rotate and pushes the coolant inside the heat exchange jacket horizontally, while the second rotating shaft drives the inclined plate stirring blades to rotate and pushes the coolant inside the heat exchange jacket upward.

[0015] Furthermore, it also includes:

[0016] A plurality of heat exchange plates are fixedly connected in a ring shape at equal intervals to the inner wall of the heat exchange vessel, and a plurality of through grooves are formed on the surface of the heat exchange plates.

[0017] Furthermore, the heat exchange plate is hollow inside, and the heat exchange plate is fixedly connected to the heat exchange jacket.

[0018] Furthermore, the sum of the width values ​​of several of the through slots is 3 / 4 of the width value of the heat exchange plate, and the specifications of the heat exchange plate are adapted to the agitator.

[0019] A cooling method for a multi-stage circulating cooling crystallization apparatus, applied to the aforementioned multi-stage circulating cooling crystallization apparatus, includes the following steps:

[0020] S1. The raw liquid is fed in through the inlet pipe on the primary reactor body;

[0021] S2. The low-temperature coolant generated in the cooler is pumped by a circulating pump and sent to the heat exchange jacket inside the three-stage reactor body.

[0022] S3. The coolant located inside the heat exchange jacket on the third-stage reactor body is sent to the coolant inlet pipe on the second-stage reactor body through the coolant discharge pipe on the third-stage reactor body, so that it passes through the coolant inlet pipe on the second-stage reactor body and enters the heat exchange jacket on the second-stage reactor body.

[0023] S4. Coolant located inside the heat exchange jacket on the secondary reactor body is sent to the coolant inlet pipe on the primary reactor body through the coolant discharge pipe on the secondary reactor body, so that it passes through the coolant inlet pipe on the primary reactor body and enters the heat exchange jacket on the primary reactor body.

[0024] S5. The coolant located inside the heat exchange jacket on the primary reactor body is sent back to the cooler for further cooling through the coolant discharge pipe on the primary reactor body.

[0025] S6. Repeat steps S2-S5 above to achieve multi-stage circulation of coolant;

[0026] S7. After the initial cooling of the raw liquid inside the first-stage reactor, the pre-cooled raw liquid is sent to the second-stage reactor through the bottom control valve. The raw liquid is then cooled again inside the second-stage reactor and sent to the third-stage reactor. After the initial circulation is completed, the above steps SS are repeated continuously to perform multi-stage circulation of the coolant and continuous crystallization of the raw liquid.

[0027] S8. The heat exchange mechanism simultaneously diffuses the lower-temperature coolant into the heat exchange jacket of the first-stage, second-stage and third-stage reactor bodies, making the coolant temperature in the heat exchange jacket more uniform.

[0028] S9. The solution to be crystallized is stirred synchronously into the first-stage, second-stage, and third-stage reactor bodies by a stirrer, so that it can fully and evenly exchange heat with the cooling liquid inside the heat exchange jacket for cooling.

[0029] S10. The precipitated crystals and mixture are discharged through the crystal discharge pipe located at the bottom of the three-stage reactor.

[0030] Compared with the prior art, the multi-stage circulating cooling crystallization device and its cooling method provided by the present invention have the following beneficial effects:

[0031] 1. The multi-stage circulating cooling crystallization device and its cooling method use a circulating pump to transport the low-temperature coolant in the cooler to the tertiary reactor. After exchanging heat with the solution inside the tertiary reactor, the cooled coolant is sequentially passed into the secondary and tertiary reactors for further heat exchange. This ensures more thorough heat exchange of the coolant. Furthermore, the raw liquid can be pre-cooled when entering the primary reactor, resulting in a slightly lower temperature when entering the secondary reactor. After further cooling inside the secondary reactor, the temperature is even lower when it enters the tertiary reactor for cooling and crystallization, thus achieving better crystallization and higher heat exchange efficiency.

[0032] 2. The multi-stage circulating cooling crystallization device and its cooling method, through the use of a heat equalization mechanism, can accelerate the diffusion of low-temperature coolant inside the heat exchange jacket after the coolant enters the jacket, making the overall temperature distribution of the coolant inside the jacket more uniform. As a result, when the raw liquid inside the heat exchange vessel is exchanging heat, the temperature of the heat exchange parts in the heat exchange jacket is generally lower, which is beneficial to improving the heat exchange efficiency of the raw liquid inside the heat exchange vessel.

[0033] 3. The multi-stage circulating cooling crystallization device and its cooling method are connected to a heat exchange jacket through a hollow heat exchange plate, so that the coolant flowing inside the heat exchange jacket can fill the interior of the heat exchange plate. With the cooperation of the through groove, the solution inside the heat exchange vessel can pass through the surface of the heat exchange plate and the inner wall of the through groove during the flow heat exchange process, and make contact heat exchange with the surface of the heat exchange plate and the inner wall of the through groove. This effectively increases the heat exchange area of ​​the solution inside the heat exchange vessel, which can further improve the cooling crystallization efficiency of the solution. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0035] Figure 1 This is a schematic diagram of the overall structure provided for an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the longitudinal cross-sectional structure of the primary reactor body provided in an embodiment of the present invention;

[0037] Figure 3 Provided for embodiments of the present invention Figure 2 Enlarged schematic diagram of the middle section structure;

[0038] Figure 4 This is a schematic diagram of the transverse cross-sectional structure of the primary reactor body provided in an embodiment of the present invention;

[0039] Figure 5 This is another cross-sectional view of the primary reactor body provided in an embodiment of the present invention;

[0040] Figure 6 Provided for embodiments of the present invention Figure 5 Enlarged structural diagram at point A in the middle;

[0041] Figure 7 This is a schematic diagram of the heat dissipation mechanism provided in an embodiment of the present invention.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Heat exchange vessel; 101. Primary vessel body; 102. Secondary vessel body; 103. Tertiary vessel body; 2. Heat exchange jacket; 3. Liquid inlet pipe; 4. Crystal liquid outlet pipe; 5. Coolant inlet pipe; 6. Coolant outlet pipe; 7. Stirrer; 8. Heat equalization mechanism; 81. First rotating shaft; 82. Second rotating shaft; 83. Flat plate stirring blade; 84. Inclined plate stirring blade; 85. Drive assembly; 851. Mounting box; 852. Impeller; 853. Flow channel; 854. First gear; 855. Second gear; 856. Gear ring; 9. Heat exchange plate; 10. Cooler; 11. Circulating pump; 12. Through groove. Detailed Implementation

[0044] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0045] Example 1:

[0046] Please see Figures 1-7 A multi-stage circulating cooling crystallization device, comprising:

[0047] Heat exchange vessel 1, heat exchange jacket 2 is provided inside heat exchange vessel 1, liquid inlet pipe 3 and liquid outlet pipe 4 are fixedly connected to the top and bottom of heat exchange vessel 1 respectively, control valve is provided at the bottom of liquid outlet pipe 4, coolant inlet pipe 5 and coolant outlet pipe 6 are fixedly connected to the heat exchange jacket 2 at the bottom and top of heat exchange vessel 1 respectively, and stirrer 7 is provided inside heat exchange vessel 1;

[0048] A heat equalization mechanism 8 is installed inside the heat exchange vessel 1. The heat equalization mechanism 8 includes several first rotating shafts 81 and second rotating shafts 82 that are equidistantly connected in a ring shape inside the heat exchange jacket 2. Several sets of flat stirring blades 83 are fixedly connected to the outer surface of the first rotating shafts 81 from top to bottom at equal intervals. Several sets of inclined stirring blades 84 are fixedly connected to the outer surface of the second rotating shafts 82 from top to bottom at equal intervals. The several first rotating shafts 81 and several second rotating shafts 82 are arranged alternately in sequence. A drive assembly 85 is provided between the first rotating shafts 81 and the second rotating shafts 82. The drive assembly 85 is used to drive the first rotating shafts 81 and the second rotating shafts 82 to rotate synchronously.

[0049] The heat exchange vessel 1 includes a primary vessel body 101, a secondary vessel body 102, and a tertiary vessel body 103. The crystal liquid discharge pipe 4 located on the primary vessel body 101 is fixedly connected to the liquid inlet pipe 3 located on the secondary vessel body 102, and the crystal liquid discharge pipe 4 located on the secondary vessel body 102 is fixedly connected to the liquid inlet pipe 3 located on the tertiary vessel body 103.

[0050] Cooler 10, whose inlet end is fixedly connected to coolant discharge pipe 6 located on primary reactor body 101;

[0051] The inlet end of the circulating pump 11 is fixedly connected to the outlet end of the cooler 10, and the outlet end of the circulating pump 11 is fixedly connected to the inlet pipe 3 located on the three-stage vessel 103.

[0052] In this embodiment, the drive assembly 85 includes a mounting box 851 fixedly installed on the inner wall of the heat exchange jacket 2. An impeller 852 is rotatably connected to the inner side of the mounting box 851. A flow channel 853 is opened on the inner side of the mounting box 851. The flow channel 853 is fixedly connected to the coolant inlet pipe 5. When the coolant discharged from the coolant inlet pipe 5 passes through the flow channel 853 and enters the interior of the heat exchange jacket 2, the coolant flows and drives the impeller 852 to rotate.

[0053] In this embodiment, an annular groove is provided inside the heat exchange vessel 1. The impeller 852 is coaxially fixedly connected to the outside of a first gear 854 located inside the annular groove. The first rotating shaft 81 and the second rotating shaft 82 are respectively fixedly connected to the outside of a second gear 855 located inside the annular groove. A toothed ring 856 is rotatably connected to the inner side of the annular groove.

[0054] Specifically, the first gear 854 and several second gears 855 mesh with the gear ring 856, so that when the first gear 854 rotates, it drives the gear ring 856 to rotate, thereby driving all the second gears 855 to rotate synchronously.

[0055] Furthermore, when the drive assembly 85 drives the first rotating shaft 81 and the second rotating shaft 82 to rotate, the first rotating shaft 81 drives the flat plate stirring blade 83 to rotate and pushes the coolant inside the heat exchange jacket 2 horizontally, while the second rotating shaft 82 drives the inclined plate stirring blade 84 to rotate and pushes the coolant inside the heat exchange jacket 2 upward.

[0056] During initial operation, the raw liquid is introduced through the inlet pipe 3 on the primary reactor 101. Then, the low-temperature coolant generated in the cooler 10 is pumped by the circulating pump 11 and pumped into the heat exchange jacket 2 inside the tertiary reactor 103. Next, the coolant located inside the heat exchange jacket 2 on the tertiary reactor 103 is sent through the coolant outlet pipe 6 on the tertiary reactor 103 into the coolant inlet pipe 5 on the secondary reactor 102, allowing it to pass through the coolant inlet pipe 5 on the secondary reactor 102 and enter the secondary reactor 102. In the heat exchange jacket 2 on the 02, the coolant inside the heat exchange jacket 2 on the secondary vessel 102 is sent to the coolant inlet pipe 5 on the primary vessel 101 through the coolant outlet pipe 6 on the secondary vessel 102. The coolant passes through the coolant inlet pipe 5 on the primary vessel 101 and enters the heat exchange jacket 2 on the primary vessel 101. Finally, the coolant inside the heat exchange jacket 2 on the primary vessel 101 is sent back to the cooler 10 for further cooling through the coolant outlet pipe 6 on the primary vessel 101.

[0057] After the initial cooling of the raw liquid inside the first-stage reactor 101, the pre-cooled raw liquid is sent to the second-stage reactor 102 through the bottom control valve. The raw liquid is then cooled again inside the second-stage reactor 102 and sent to the third-stage reactor 103. After the initial circulation is completed, the above-mentioned coolant circulation process is repeated continuously to carry out multi-stage circulation of the coolant and continuous crystallization of the raw liquid.

[0058] When the coolant enters the heat exchange vessel 1, it enters the heat exchange jacket 2 through the coolant inlet pipe 5. During the entry process, it passes through the flow channel 853 inside the mounting box 851. As the coolant flows through the flow channel 853, it drives the impeller 852 to rotate. The rotation of the impeller 852 drives the first gear 854 to rotate. Under the transmission action of the gear ring 856, the rotation of the first gear 854 drives the second gear 855 to rotate synchronously. The rotation of the second gear 855 drives the first rotating shaft 81 and the second rotating shaft 82 to rotate synchronously. This allows the flat plate stirring blade 83 and the inclined plate stirring blade 84 to rotate synchronously. The rotation of the inclined plate stirring blade 84 can quickly transport the coolant from the bottom upwards, while the rotation of the flat plate stirring blade 83 can push the coolant horizontally. This allows the low-temperature coolant to diffuse quickly and fully after entering the heat exchange jacket 2, resulting in a more uniform temperature of the coolant inside the heat exchange jacket 2. As a result, the solution inside the heat exchange vessel 1 can achieve more efficient heat exchange under the stirring of the stirrer 7.

[0059] Example 2:

[0060] Please see Figure 2 , Figure 4This embodiment provides a technical solution based on the above embodiments, which further includes:

[0061] Several heat exchange plates 9 are fixedly connected in a ring shape at equal intervals to the inner wall of the heat exchange vessel 1, and several through grooves 12 are opened on the surface of the heat exchange plates 9.

[0062] Specifically, the heat exchange plate 9 is hollow inside, and the heat exchange plate 9 is fixedly connected to the heat exchange jacket 2.

[0063] Furthermore, the sum of the width values ​​of several through slots 12 is 3 / 4 of the width value of the heat exchange plate 9, which makes the slot opening area of ​​the through slots 12 larger, so as not to obstruct the flow of the solution inside the heat exchange vessel 1. The specifications of the heat exchange plate 9 are compatible with the stirrer 7, so that the setting of the heat exchange plate 9 will not interfere with the normal operation of the stirrer 7.

[0064] During use, the coolant inside the heat exchange jacket 2 flows into the heat exchange plate 9, which, with the cooperation of the heat exchange plate 9 and the through groove 12, greatly increases the contact area between the heat exchange jacket 2 and the solution inside the heat exchange vessel 1, thereby effectively improving the heat exchange efficiency of the coolant and making the cooling and crystallization effect of the solution better.

[0065] Example 3:

[0066] This embodiment provides a cooling method for a multi-stage circulating cooling crystallization device based on the above embodiments, applied to the aforementioned multi-stage circulating cooling crystallization device, and includes the following steps:

[0067] S1. The raw liquid is fed in through the liquid inlet pipe 3 on the primary reactor body 101;

[0068] S2. The low-temperature coolant generated in the cooler 10 is pumped by the circulating pump 11 and pumped to the heat exchange jacket 2 inside the three-stage vessel 103.

[0069] S3. Cooling liquid located inside the heat exchange jacket 2 on the third-stage vessel 103 is sent into the cooling liquid inlet pipe 5 on the second-stage vessel 102 through the cooling liquid discharge pipe 6 on the third-stage vessel 103, so that it passes through the cooling liquid inlet pipe 5 on the second-stage vessel 102 and enters the heat exchange jacket 2 on the second-stage vessel 102.

[0070] S4. Cooling liquid located inside the heat exchange jacket 2 on the secondary vessel 102 is sent into the cooling liquid inlet pipe 5 on the primary vessel 101 through the cooling liquid discharge pipe 6 on the secondary vessel 102, so that it passes through the cooling liquid inlet pipe 5 on the primary vessel 101 and enters the heat exchange jacket 2 on the primary vessel 101.

[0071] S5. The coolant located inside the heat exchange jacket 2 on the primary reactor body 101 is sent back to the cooler 10 for further cooling through the coolant discharge pipe 6 on the primary reactor body 101.

[0072] S6. Repeat steps S2-S5 above to achieve multi-stage circulation of coolant;

[0073] S7. After the initial cooling of the raw liquid inside the first-stage reactor 101, the pre-cooled raw liquid is sent to the second-stage reactor 102 through the bottom control valve. The raw liquid is then cooled again inside the second-stage reactor 102 and sent to the third-stage reactor 103. After the initial circulation is completed, the above steps S2-S5 are repeated continuously to carry out multi-stage circulation of the coolant and continuous crystallization of the raw liquid.

[0074] S8. The heat exchange mechanism 8 simultaneously diffuses the lower-temperature coolant into the heat exchange jacket 2 of the primary vessel 101, secondary vessel 102 and tertiary vessel 103, so that the coolant temperature in the heat exchange jacket 2 is relatively uniform.

[0075] S9. The solution to be crystallized is stirred synchronously by the stirrer 7 into the first stage vessel 101, the second stage vessel 102 and the third stage vessel 103, so that it can fully and evenly exchange heat with the cooling liquid inside the heat exchange jacket 2 to cool down.

[0076] S10. The precipitated crystals and mixture are discharged through the crystal discharge pipe 4 located at the bottom of the three-stage reactor body 103.

[0077] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A multi-stage circulating cooling crystallization device, characterized in that, include A heat exchange vessel (1) is provided with a heat exchange jacket (2) inside. The top and bottom of the heat exchange vessel (1) are respectively fixedly connected to a liquid inlet pipe (3) and a liquid discharge pipe (4). A control valve is provided at the bottom of the liquid discharge pipe (4). The bottom and top of the heat exchange vessel (1) are respectively provided with a coolant inlet pipe (5) and a coolant discharge pipe (6) fixedly connected to the heat exchange jacket (2). A stirrer (7) is provided inside the heat exchange vessel (1). A heat equalization mechanism (8) is installed inside the heat exchange vessel (1). The heat equalization mechanism (8) includes a plurality of first rotating shafts (81) and second rotating shafts (82) that are equidistantly connected in a ring shape inside the heat exchange jacket (2). A plurality of flat stirring blades (83) are fixedly connected at equal intervals from top to bottom on the outer surface of the first rotating shafts (81). A plurality of inclined stirring blades (84) are fixedly connected at equal intervals from top to bottom on the outer surface of the second rotating shafts (82). The plurality of first rotating shafts (81) and the plurality of second rotating shafts (82) are arranged alternately in sequence. A driving assembly (85) is provided between the first rotating shafts (81) and the second rotating shafts (82). The driving assembly (85) is used to drive the first rotating shafts (81) and the second rotating shafts (82) to rotate synchronously. The heat exchange vessel (1) includes a primary vessel body (101), a secondary vessel body (102), and a tertiary vessel body (103). The crystal liquid discharge pipe (4) located on the primary vessel body (101) is fixedly connected to the liquid inlet pipe (3) located on the secondary vessel body (102), and the crystal liquid discharge pipe (4) located on the secondary vessel body (102) is fixedly connected to the liquid inlet pipe (3) located on the tertiary vessel body (103). The cooler (10) has its inlet end fixedly connected to the coolant outlet pipe (6) located on the primary reactor body (101); The circulation pump (11) has its inlet end fixedly connected to the outlet end of the cooler (10), and the outlet end of the circulation pump (11) is fixedly connected to the inlet pipe (3) located on the three-stage vessel body (103).

2. The multi-stage circulating cooling crystallization device according to claim 1, characterized in that, The drive assembly (85) includes a mounting box (851) fixedly installed on the inner wall of the heat exchange jacket (2). An impeller (852) is rotatably connected to the inner side of the mounting box (851). A flow channel (853) is opened on the inner side of the mounting box (851). The flow channel (853) is fixedly connected to the coolant inlet pipe (5). When the coolant discharged from the coolant inlet pipe (5) passes through the flow channel (853) and enters the interior of the heat exchange jacket (2), the coolant flows and drives the impeller (852) to rotate.

3. The multi-stage circulating cooling crystallization device according to claim 2, characterized in that, The heat exchange vessel (1) has an annular groove inside. The impeller (852) is coaxially fixedly connected to a first gear (854) located inside the annular groove. The first rotating shaft (81) and the second rotating shaft (82) are respectively fixedly connected to a second gear (855) located inside the annular groove. A gear ring (856) is rotatably connected to the inner side of the annular groove.

4. The multi-stage circulating cooling crystallization device according to claim 3, characterized in that, The first gear (854) and several second gears (855) are all engaged with the gear ring (856).

5. The multi-stage circulating cooling crystallization device according to claim 4, characterized in that, When the drive assembly (85) drives the first rotating shaft (81) and the second rotating shaft (82) to rotate, the first rotating shaft (81) drives the flat plate stirring blade (83) to rotate and pushes the coolant inside the heat exchange jacket (2) horizontally, and the second rotating shaft (82) drives the inclined plate stirring blade (84) to rotate and pushes the coolant inside the heat exchange jacket (2) upward.

6. The multi-stage circulating cooling crystallization device according to claim 5, characterized in that, Also includes: A plurality of heat exchange plates (9) are fixedly connected in a circular shape at equal intervals to the inner wall of the heat exchange vessel (1), and a plurality of through grooves (12) are provided on the surface of the heat exchange plates (9).

7. The multi-stage circulating cooling crystallization apparatus according to claim 6, characterized in that, The heat exchange plate (9) is hollow inside, and the heat exchange plate (9) is fixedly connected to the heat exchange jacket (2).

8. The multi-stage circulating cooling crystallization apparatus according to claim 7, characterized in that, The sum of the width values ​​of several of the through slots (12) is 3 / 4 of the width value of the heat exchange plate (9), the specifications of which are adapted to the stirrer (7).

9. A cooling method for a multi-stage circulating cooling crystallization apparatus, applied to the multi-stage circulating cooling crystallization apparatus as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. The raw liquid is fed in through the liquid inlet pipe (3) on the primary reactor body (101); S2. The low-temperature coolant generated in the cooler (10) is pumped by the circulating pump (11) and pumped to the heat exchange jacket (2) inside the three-stage vessel body (103); S3. The coolant located inside the heat exchange jacket (2) on the third stage vessel (103) is sent into the coolant inlet pipe (5) on the second stage vessel (102) through the coolant discharge pipe (6) on the third stage vessel (103), so that it passes through the coolant inlet pipe (5) on the second stage vessel (102) and enters the heat exchange jacket (2) on the second stage vessel (102); S4. The coolant located inside the heat exchange jacket (2) on the secondary vessel (102) is sent into the coolant inlet pipe (5) on the primary vessel (101) through the coolant discharge pipe (6) on the secondary vessel (102), so that it passes through the coolant inlet pipe (5) on the primary vessel (101) and enters the heat exchange jacket (2) on the primary vessel (101); S5. The coolant inside the heat exchange jacket (2) on the primary reactor body (101) is sent back to the cooler (10) for further cooling through the coolant discharge pipe (6) on the primary reactor body (101). S6. Repeat steps S2-S5 above to achieve multi-stage circulation of coolant; S7. After the initial cooling of the raw liquid inside the first-stage vessel (101), the pre-cooled raw liquid is sent to the second-stage vessel (102) through the bottom control valve. The raw liquid is then cooled again inside the second-stage vessel (102) and sent to the third-stage vessel (103). After the initial cycle is completed, the above steps S2-S5 are repeated continuously to carry out multi-stage circulation of the coolant and continuous crystallization of the raw liquid. S8. The low-temperature coolant entering the heat exchange jacket (2) of the first-stage vessel (101), second-stage vessel (102) and third-stage vessel (103) is rapidly diffused through the heat equalization mechanism (8) so that the coolant temperature in each part of the heat exchange jacket (2) is relatively uniform. S9. Stir the solution to be crystallized that enters the first stage vessel (101), the second stage vessel (102) and the third stage vessel (103) simultaneously using a stirrer (7) so that it can fully and evenly exchange heat with the cooling liquid inside the heat exchange jacket (2) to cool down. S10. The precipitated crystals and mixture are discharged through the crystal discharge pipe (4) at the bottom of the three-stage reactor (103).

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