Internal circulation continuous crystallization system

Abstract

The utility model discloses an internal circulation continuous crystallization system. Comprising a steam line, a plurality of heaters and a plurality of separators, the steam line is connected with the heaters and the separators, a first feeding port is formed in the upper portion of each separator, a second feeding port and a steam inlet are formed in the lower portion of each separator, a propeller is arranged at the bottom of each separator, and an inner cylinder is arranged outside fan blades of each propeller; the propeller is used for propelling materials in the inner cylinder to the upper portion of the separator. Materials in the inner barrel can be pushed upwards through the propeller, the materials pushed by the propeller can be evaporated again through the steam, then internal circulation of the materials in the separator is formed, the contact area of the materials and the steam can be increased, the contact time of the materials and the steam can be shortened, the steam can heat and evaporate the materials more sufficiently, and the separation efficiency is improved. Therefore, the evaporation efficiency is improved. Material separation is promoted, material deposition is reduced, the flexibility and energy-saving and consumption-reducing effects of the system are improved, and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crystallization systems, and particularly relates to an internal circulation continuous crystallization system. BACKGROUND

[0002] A crystallization system is used to concentrate solute in a solution to a saturated state by using the difference in evaporation rates of solvents at different temperatures, and then to precipitate crystals. During evaporation, the solution is heated in a heater, and solvent molecules escape from the liquid surface to form vapor after obtaining sufficient energy. The vapor is then condensed into liquid in a condenser to recover part of the solvent. At the same time, the solute in the solution is gradually concentrated during evaporation, and when the concentration reaches saturation, the solute begins to precipitate crystals.

[0003] As an important device in an evaporation crystallization system, a separator undertakes the key task of material separation and purification. However, the existing separator usually uses simple physical sedimentation or natural convection to separate materials, which results in limited contact area and contact time of materials and vapor, and insufficient heating and evaporation of materials by vapor, thereby reducing evaporation efficiency. CONTENT OF THE UTILITY MODEL

[0004] The technical problem solved by the present application is to provide an internal circulation continuous crystallization system to solve the problems of insufficient contact area and contact time of materials and vapor, and insufficient heating and evaporation of materials by vapor, thereby reducing evaporation efficiency.

[0005] To solve the above technical problems, one technical solution adopted by the present application is to provide an internal circulation continuous crystallization system, which comprises a vapor line, a plurality of heaters and a plurality of separators. The vapor line is connected with the heaters and the separators. The upper part of each separator is provided with a first feed inlet, and the lower part of each separator is provided with a second feed inlet and a vapor inlet. The bottom of each separator is provided with a propeller. The outer part of the fan blade of the propeller is provided with an inner cylinder. The propeller is used to push the materials in the inner cylinder to the upper part of the separator.

[0006] In some embodiments, the height of the inner cylinder is greater than the vapor inlet of the separator and less than the second feed inlet of the separator.

[0007] In some embodiments, the inner cylinder is cylindrical, and the diameter of the inner cylinder is adapted to the outer diameter of the fan blade of the propeller.

[0008] In some embodiments, the heater includes a first-effect heater and a second-effect heater, and the separator includes a first-effect separator, a second-effect separator, and a third-effect separator; the crystallization system further includes a feed line, which includes multiple feed branches, each feed branch corresponding to one of the first-effect separators, one of the second-effect separators, or one of the third-effect separators; the outlet of the first-effect separator is connected to a first-effect circulating pump, the outlet of the first-effect circulating pump is connected to the inlet of the first-effect heater, the outlet of the first-effect circulating pump is also connected to the outlet of the second-effect separator, and a feed branch is connected to the second-effect separator; the outlet of the second-effect heater is connected to a second-effect circulating pump, the outlet of the second-effect circulating pump is connected to the outlet of the second-effect separator, the outlet of the second-effect circulating pump is also connected to a second-effect discharge pump, the outlet of the second-effect discharge pump is connected to the third-effect separator and the discharge line, the outlet of the third-effect separator is connected to a third-effect discharge pump, and the third-effect discharge pump is connected to the discharge line.

[0009] In some embodiments, the crystallization system further includes a non-condensable gas line, a condenser, and a vacuum pump. The heater has non-condensable gas outlets at both its upper and lower parts, the condenser has a non-condensable gas inlet at its upper part, and the condenser also has non-condensable gas outlets at its upper and lower parts. The non-condensable gas line is located between the non-condensable gas outlet of the heater and the non-condensable gas inlet of the condenser, and between the non-condensable gas outlet of the condenser and the vacuum pump. The vacuum pump is used to discharge the non-condensable gas.

[0010] In some embodiments, the crystallization system further includes a condensate line, and the lower parts of the first-effect heater, the second-effect heater and the third-effect separator are all provided with condensate outlets, the lower part of the condenser is provided with a condensate inlet, the condensate line is connected between the condensate outlet and the condensate inlet, and the condenser is connected to a first condensate pump, which is used to discharge the condensate in the condenser.

[0011] In some embodiments, the steam line includes a main steam line, a steam circuit, and multiple steam branches. The main steam line is connected to the steam branches, and the steam branches are respectively connected to the steam inlet of the heater or separator. The steam circuit is connected to a steam circulation pump, and the outlet of the steam circulation pump is connected to the main steam line.

[0012] The beneficial effects of this application are: the propeller can push the material inside the inner cylinder upwards, and the steam can re-evaporate the material pushed by the propeller, thus forming an internal circulation of the material within the separator. This accelerates the contact area and contact time between the material and the steam, allowing the steam to more fully heat and evaporate the material, thereby improving evaporation efficiency. It also promotes material separation, reduces material sedimentation, improves system flexibility and energy saving, and reduces production costs. Attached Figure Description

[0013] Figure 1 This is a structural schematic diagram according to an embodiment of this application;

[0014] Figure 2 This is a schematic diagram of the structure of a single-effect heater according to an embodiment of this application;

[0015] Figure 3 This is a schematic diagram of the structure of a single-effect separator according to an embodiment of this application;

[0016] Figure 4 This is a schematic diagram of the structure of a double-effect heater and a double-effect separator according to an embodiment of this application;

[0017] Figure 5 This is a schematic diagram of the structure of a three-effect separator according to an embodiment of this application;

[0018] Figure 6 This is a schematic diagram of the structure of a condenser according to an embodiment of this application. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0021] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" or "several" means two or more, unless otherwise explicitly specified.

[0023] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0024] Figure 1 - Figure 6 An embodiment of the present application is shown, including a steam line 10, a plurality of heaters and a plurality of separators. The steam line 10 includes a main steam line 101, a steam circuit 103 and a plurality of steam branches. The main steam line 101 is connected to the steam branches, and the steam branches are respectively connected to the steam inlets of the heaters or separators. The steam circuit 103 is connected to the steam outlets of the heaters or separators.

[0025] In some embodiments, a propeller 32 is provided at the bottom of the separator, and an inner cylinder 33 is provided outside the blades of the propeller 32. The propeller 32 is used to push the material in the inner cylinder 33 upwards towards the top of the separator. The propeller 32 pushes the material in the inner cylinder 33 upwards, and steam can re-evaporate the material pushed by the propeller 32, thus forming an internal circulation of the material within the separator. This accelerates the contact area and contact time between the material and steam, allowing the steam to more fully heat and evaporate the material, thereby improving evaporation efficiency. This promotes material separation, reduces material deposition, improves system flexibility and energy saving, and reduces production costs.

[0026] A propeller 32 can be installed at the bottom of the triple-effect separator 3. Alternatively, a propeller can be installed at the bottom of the single-effect separator 11 or the double-effect separator 22. The propeller 32 is a low-speed, low-head propeller, and its head can be adapted to the height of the inner cylinder 33.

[0027] In some embodiments, the feed inlet 330 of the triple-effect separator 33 includes a first feed inlet 3301 and a second feed inlet 3302. The first feed inlet 3301 is located at the upper part of the triple-effect separator 33, and the second feed inlet 3302 and steam inlet 310 are located at the lower part of the triple-effect separator 33. The height of the inner cylinder 33 is greater than the steam inlet 310 of the separator and smaller than the second feed inlet 3302 of the separator. This ensures that the material propelled by the propeller 32 can fully contact the steam, ensuring that the material is fully heated and evaporated.

[0028] In some embodiments, the inner cylinder 33 is cylindrical, and its diameter is adapted to the outer diameter of the blades of the propeller 32. This prevents the accumulation of material inside the inner cylinder 33 and ensures that the material inside the inner cylinder 33 can be fully propelled into the separator.

[0029] In some embodiments, each steam branch is provided with a first control valve, which is used to control the opening and closing of the steam branch. A second control valve is connected between the steam branch and the steam circuit 103, which is used to control the opening and closing of the connection between the steam branch and the steam circuit 103. A third control valve is provided on the steam circuit 103 between adjacent heaters or separators. The third control valve is located behind the steam flow direction of the second control valve and is used to control the opening and closing of the steam circuit 103 between adjacent heaters or separators.

[0030] In this application, the first control valve can independently control the opening and closing of each steam branch. When a heater and separator are opened and closed by the first control valve, the second and third control valves cooperate with the first control valve to make steam flow out of the steam circuit 103. This allows the operator to select which heater or separator, or their combination, to use for crystallization according to specific process requirements, thus making it applicable to a variety of different crystallization processes and production scenarios.

[0031] The control valve can be a ball valve, gate valve, butterfly valve, solenoid valve, etc. In some embodiments, the first control valve, the second control valve, and the third control valve are all butterfly valves.

[0032] In some embodiments, the heater includes a single-effect heater 1 and a double-effect heater 2, and the separator includes a single-effect separator 11, a double-effect separator 22, and a triple-effect separator 3; the steam branch includes a first steam branch 1021, a second steam branch 1022, and a third steam branch 1023. The first steam branch 1021 is connected to the steam inlet 110 of the single-effect heater 1, the steam outlet 120 of the single-effect heater 1 is connected to the steam inlet 111 of the single-effect separator 11, the steam outlet 112 of the single-effect separator 11 is connected to the steam circuit 103, the second steam branch 1022 is connected to the steam inlet 210 of the double-effect heater 2, the double-effect heater 2 is connected to the double-effect separator 22, steam enters the double-effect separator 22 from the double-effect heater 2, the steam outlet 221 of the double-effect separator 22 is connected to the steam circuit 103, the third steam branch 1023 is connected to the steam inlet 310 of the triple-effect separator 3, and the steam outlet 320 of the triple-effect separator 3 is connected to the steam circuit 103. A butterfly valve is installed on the first steam branch 1021, the second steam branch 1022, the third steam branch 1023, between the second steam branch 1022 and the steam circuit 103, between the third steam branch 1023 and the steam circuit 103, between the first-effect separator 11 and the second-effect separator 22, and between the second-effect separator 22 and the third-effect separator 3. The butterfly valve on the first steam branch 1021 is the first butterfly valve F1, the butterfly valve on the second steam branch 1022 is the second butterfly valve F2, the butterfly valve on the third steam branch 1023 is the third butterfly valve F3, the butterfly valve between the second steam branch 1022 and the steam circuit 103 is the fourth butterfly valve F4, the butterfly valve between the third steam branch 1023 and the steam circuit 103 is the fifth butterfly valve F5, the butterfly valve between the first-effect separator 11 and the second-effect separator 22 is the sixth butterfly valve F6, and the butterfly valve between the second-effect separator 22 and the third-effect separator 3 is the seventh butterfly valve F7.

[0033] The operation of the single-effect heater 1, double-effect heater 2, single-effect separator 11, double-effect separator 22, and triple-effect separator 3 can be controlled via butterfly valves. For example, closing butterfly valves F1, F2, F4, F5, F6, and F7, and opening butterfly valve F3, allows triple-effect separator 3 to be used alone to produce viscous or large-crystal products. Alternatively, closing butterfly valves F3 and F5, and opening butterfly valves F1, F2, F4, F6, and F7, allows operation of single-effect heater 1, double-effect heater 2, single-effect separator 11, and double-effect separator 22, while closing triple-effect separator 3, allowing production of viscous or small-crystal products via double-effect separator 22. All butterfly valves can also be opened simultaneously, allowing single-effect heater 1, double-effect heater 2, single-effect separator 11, double-effect separator 22, and triple-effect separator 3 to operate concurrently. By opening and closing the butterfly valve, the system can operate individually for single-effect operation, using one-effect heater 1 and one-effect separator 11, two-effect heater 2 and two-effect separator 22, and three-effect separator 3. It can also achieve dual-effect operation by combining one-effect heater 1, one-effect separator 11, two-effect heater 2 and two-effect separator 22, one-effect heater 1, one-effect separator 11 and three-effect separator 3, and two-effect heater 2, two-effect separator 22 and three-effect separator 3. Furthermore, it can achieve triple-effect operation by using one-effect heater 1, two-effect heater 2, one-effect separator 11, two-effect separator 22 and three-effect separator 3 together. This greatly enhances the application of the crystallization system in various crystallization processes and production scenarios. In the event of a failure in one unit, maintenance can be easily performed without affecting the operation of other heaters or separators.

[0034] In some embodiments, the crystallization system further includes a feed line 20, which includes multiple feed branches 201. Each feed branch 201 is connected to the inlet 113 of a first-effect separator 11, the inlet 222 of a second-effect separator 22, or the inlet 330 of a third-effect separator 3. The outlet 114 of the first-effect separator 11 is connected to a first-effect circulating pump 12. The outlet of the first-effect circulating pump 12 is connected to the inlet 130 of a first-effect heater 1. The outlet of the first-effect circulating pump 12 is also connected to the outlet 223 of the second-effect separator 22, as well as the feed branch 201 connected to the second-effect separator 22. The outlet 140 of the first-effect heater 1 is connected to the first-effect circulating pump 12.

[0035] In some embodiments, the feed pipe 220 of the second-effect heater is connected to the second-effect separator 22, the outlet 230 of the second-effect heater 2 is connected to the second-effect circulating pump 23, the outlet of the second-effect circulating pump 23 is connected to the outlet 223 of the second-effect separator 22, the outlet of the second-effect circulating pump 23 is also connected to the second-effect discharge pump 24, the outlet of the second-effect discharge pump 24 is connected to the third-effect separator 3 and the discharge line 30, the outlet 340 of the third-effect separator 3 is connected to the third-effect discharge pump 31, and the third-effect discharge pump 31 is connected to the discharge line 30. The feed line 20 can transport materials to different effect stage separators to meet production needs. The first-effect circulating pump 12 and the second-effect circulating pump 23 promote the full heating and evaporation of materials, improving energy efficiency. The materials in the second-effect circulation can be circulated and heated, optimizing energy utilization. The multi-stage separation and circulating pump design ensures system stability, reduces the impact of failures, and improves product purity and yield.

[0036] In some embodiments, the crystallization system further includes multiple feed control lines 202. One end of each feed control line 202 is equipped with a level transmitter 203, which is mounted on a heater or separator. The other end of each feed control line 202 is equipped with a feed flange ball valve 204, which is mounted on a feed branch 201. The level transmitter 203 controls the opening or closing of the feed flange ball valve 204 based on the liquid level in the heater or separator, thereby opening or closing the feed branch 201. The level transmitter 203 monitors changes in the liquid level in the heater or separator in real time and transmits the information to the control system. The control system can be a microcontroller or a PLC control box. The control system automatically adjusts the state of the feed flange ball valve 204 based on real-time data, precisely controlling the feed branch 201. Precise liquid level control maintains optimal material quantity, improves heating, evaporation, or separation efficiency, stabilizes system operation, and reduces the decrease in processing efficiency.

[0037] In some embodiments, the crystallization system further includes a discharge control line 301, which controls the discharge of materials from the crystallization system. The discharge control line 301 includes a densitometer 302 and multiple discharge flange ball valves 303. The densitometer 302 is mounted on the discharge line 30, and the discharge flange ball valves 303 are respectively located between the first-effect circulating pump 12 and the discharge line 30, between the second-effect discharge pump 24 and the discharge line 30, between the third-effect discharge pump 31 and the discharge line 30, and at the end of the discharge line 30. The densitometer 302 monitors the material density in real time, ensuring that only materials meeting the standards are discharged, thus guaranteeing product quality. The multiple discharge flange ball valves 303 can be adjusted independently or collaboratively to adapt to different production needs. The densitometer 302 and the ball valves work together to prevent the discharge of materials with abnormal density, avoiding accidents. This achieves precise control and timely discharge of the crystallization system, reducing waste and improving equipment utilization and production efficiency.

[0038] In some embodiments, the crystallization system further includes a drain outlet and a return outlet, and the discharge control line 301 is connected to the drain outlet and the return outlet.

[0039] In some embodiments, the crystallization system further includes a non-condensable gas line 40, a condenser 4, and a vacuum pump 41. The heater has non-condensable gas outlets at both its upper and lower parts (non-condensable gas outlet 150 for the first-effect heater and non-condensable gas outlet 250 for the second-effect heater). The condenser 4 has a non-condensable gas inlet 420 at its upper part and non-condensable gas outlets 430 at both its upper and lower parts. The non-condensable gas line 40 is positioned between the non-condensable gas outlet of the heater and the non-condensable gas inlet 420 of the condenser 4, and between the non-condensable gas outlet 430 of the condenser 4 and the vacuum pump 41. The vacuum pump 41 is used to discharge the non-condensable gas. The heater has non-condensable gas outlets at both its upper and lower parts, enabling effective collection and discharge of non-condensable gas. The non-condensable gas inlet at the upper part of the condenser 4 is connected to the heater outlet to ensure smooth transfer and prevent accumulation. The non-condensable gas outlet at the lower part of the condenser 4 is connected to the vacuum pump 41 to ensure complete discharge and improve system efficiency.

[0040] In some embodiments, the crystallization system further includes a condensate line 50. The lower parts of the first-effect heater 1, the second-effect heater 2, and the third-effect separator 3 are all provided with condensate outlets (condensate outlet 160 for the first-effect heater, condensate outlet 240 for the second-effect heater, and condensate outlet 350 for the third-effect separator). A steam inlet 410 is provided above the condenser 4, connected to the steam circuit 103. A condensate inlet 440 is provided at the lower part of the condenser 4. The condensate line 50 connects the condensate outlet and the condensate inlet 440. A first condensate pump 501 is connected to the condenser 4 to discharge the condensate from the condenser 4. With condensate outlets at the lower parts of the first-effect heater 1, the second-effect heater 2, and the third-effect separator 3, connected to the condensate line 50, the system collects and recovers the condensate generated by the equipment. A condensate outlet 450 is also provided at the lower part of the condenser 4, connected to the condensate line 50, ensuring complete condensate recovery and reducing water waste. Reduce operating costs and improve energy efficiency.

[0041] In some embodiments, the steam circuit 103 is connected to a steam circulation pump 104, and the outlet of the steam circulation pump 104 is connected to the main steam line 101. This enables the reuse of steam, reduces resource waste, and lowers operating costs.

[0042] In some embodiments, the heater is connected to the condenser 4, the end of the steam circuit 103 is connected to the steam circulation pump 104, the outlet of the steam circulation pump 104 is connected to the main steam line 101, a temperature control circuit 80 is provided between the end of the steam circuit 103 and the condenser 4, and a temperature control valve 105 is provided on the temperature control circuit 80. The temperature control valve 105 is used to control the material temperature of the crystallization system according to the temperature of the steam circuit 103.

[0043] The steam circulation pump 104 connects the end of the steam circuit 103 to the main steam line 101, enabling steam recycling. This not only reduces steam waste but also improves the overall energy efficiency of the system. The temperature control circuit 80 and the temperature control valve 105 allow for precise control of the material temperature in the crystallization system. The temperature control valve 105 automatically adjusts its opening based on the temperature of the steam circuit 103, thereby regulating the amount of steam entering the system and controlling the material temperature. This ensures the stability and consistency of the crystallization process, improving product quality and yield.

[0044] In some embodiments, a second condensate pump 502 is provided on the condensate line 50 connected to the condensate outlet 240 of the double-effect heater 2. The second condensate pump 502 is used to transport the condensate in the double-effect heater 2 to the condenser 4. This enables the condensate to be transported to the condenser 4 quickly and effectively, avoiding accumulation, ensuring timely recovery and reuse, and improving water resource utilization efficiency.

[0045] In some embodiments, the sealed inlets of the first-effect circulating pump 12, the second-effect circulating pump 23, the second-effect discharge pump 24, the first condensate pump 501, the second condensate pump 502, the third-effect discharge pump 31, and the vacuum pump 41 are all connected to the pump sealing inlet pipe 60; the sealed outlets of the first-effect circulating pump 12, the second-effect circulating pump 23, the second-effect discharge pump 24, the first condensate pump 501, the second condensate pump 502, the third-effect discharge pump 31, and the vacuum pump 41 are all connected to the pump sealing return pipe 70. The sealing inlet of each pump is connected to the pump sealing inlet pipe 60, and the sealing outlet is connected to the return pipe, ensuring sealing during operation, preventing material or condensate leakage, and ensuring stable system operation.

[0046] The above are merely embodiments of this application and do not limit the scope of this patent application. Any equivalent structural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. An internal circulation continuous crystallization system, characterized in that, It includes a steam line, multiple heaters and multiple separators. The steam line is connected to the heaters and separators. The separator has a first feed inlet at the top and a second feed inlet and a steam inlet at the bottom. A propeller is provided at the bottom of the separator. An inner cylinder is provided outside the fan blades of the propeller. The propeller is used to push the material in the inner cylinder towards the top of the separator.

2. The internal circulation continuous crystallization system according to claim 1, characterized in that, The height of the inner cylinder is greater than the steam inlet of the separator, but less than the second feed inlet of the separator.

3. The internal circulation continuous crystallization system according to claim 1, characterized in that, The inner cylinder is cylindrical, and its diameter is adapted to the outer diameter of the propeller blades.

4. The internal circulation continuous crystallization system according to any one of claims 1-3, characterized in that, The heater includes a single-effect heater and a double-effect heater; the separator includes a single-effect separator, a double-effect separator, and a triple-effect separator; the crystallization system also includes a feed line, which includes multiple feed branches, each feed branch corresponding to one of the single-effect separators, a double-effect separator, or a triple-effect separator. The outlet of the single-effect separator is connected to a single-effect circulating pump, the outlet of the single-effect circulating pump is connected to the inlet of the single-effect heater, the outlet of the single-effect circulating pump is also connected to the outlet of the double-effect separator, and a feed branch is connected to the double-effect separator. The outlet of the double-effect heater is connected to a double-effect circulating pump, the outlet of the double-effect circulating pump is connected to the outlet of the double-effect separator, the outlet of the double-effect circulating pump is also connected to a double-effect discharge pump, the outlet of the double-effect discharge pump is connected to the triple-effect separator and the discharge line, the outlet of the triple-effect separator is connected to a triple-effect discharge pump, and the triple-effect discharge pump is connected to the discharge line.

5. The internal circulation continuous crystallization system according to claim 4, characterized in that, The crystallization system also includes a non-condensable gas line, a condenser, and a vacuum pump. The heater has non-condensable gas outlets at both the top and bottom. The condenser has a non-condensable gas inlet at the top and non-condensable gas outlets at both the top and bottom. The non-condensable gas line is located between the non-condensable gas outlet of the heater and the non-condensable gas inlet of the condenser, and between the non-condensable gas outlet of the condenser and the vacuum pump. The vacuum pump is used to discharge the non-condensable gas.

6. The internal circulation continuous crystallization system according to claim 5, characterized in that, The crystallization system also includes a condensate line. The lower parts of the first-effect heater, the second-effect heater, and the third-effect separator are all provided with condensate outlets. The lower part of the condenser is provided with a condensate inlet. The condensate line is connected between the condensate outlet and the condensate inlet. The condenser is connected to a first condensate pump, which is used to discharge the condensate in the condenser.

7. The internal circulation continuous crystallization system according to claim 1, characterized in that, The steam line includes a main steam line, a steam circuit, and multiple steam branches. The main steam line is connected to the steam branches, and the steam branches are respectively connected to the steam inlet of the heater or separator. The steam circuit is connected to a steam circulation pump, and the outlet of the steam circulation pump is connected to the main steam line.

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