Mine water separation and crystallization system and method based on transcritical CO2 cycle waste heat utilization

Abstract

The application relates to a mine water separation and crystallization system and method based on cross-critical CO2 cycle waste heat utilization in the technical field of mine water resource utilization and heat damage treatment, which comprises a cross-critical CO2 refrigeration module, a sodium chloride brine separation and crystallization module, a sodium sulfate brine separation and crystallization module, a mother liquor drying module and a steam auxiliary heat source module. In the application, the supercritical CO2 waste heat generated by the cross-critical CO2 refrigeration module is utilized in stages, is first supplied to a sodium chloride single / multiple-effect countercurrent evaporation crystallization system, is then supplied to a sodium sulfate single / multiple-effect cocurrent evaporation crystallization system, and is finally returned to the cross-critical CO2 refrigeration module for recycling. The sodium chloride brine separation and crystallization module can adopt a countercurrent three-effect process, the sodium sulfate brine separation and crystallization module can adopt a cocurrent two-effect process, and an auxiliary heat source is arranged. The application realizes efficient separation and resource recovery of mine water salt, and compared with a traditional process, can reduce steam consumption by 50-95%, and has remarkable energy-saving and environmental protection benefits.

Description

Technical Field

[0001] This application relates to the field of mine water resource utilization and heat hazard control technology, and in particular to a mine water separation and crystallization system and method based on transcritical CO2 cycle waste heat utilization. Background Technology

[0002] The mine water has an annual output of over 6 billion cubic meters, containing highly soluble salts (such as NaCl and Na2SO4). Traditional desalination technologies are costly and have low utilization rates, resulting in ineffective salt resource recovery. This is because traditional recovery technologies are primarily evaporation-crystallization technologies, which consume heat to evaporate, concentrate, and dry the salt product. Traditional evaporation-crystallization relies on expensive steam (≥200 RMB / ton) or electricity (mechanical compression technology, MVR), leading to high processing costs. Therefore, a low-energy-consumption, high-recovery-rate solution is urgently needed.

[0003] In addition to the aforementioned challenges in mine water management, there is also the issue of heat hazard control during mining operations. Without cooling measures, miners will work in a high-temperature and high-humidity environment of 35-40℃ and nearly 100% humidity. Existing Freon refrigeration systems suffer from significant cooling losses (underground temperatures remain above 26℃), wasted condensation heat, and environmental problems, resulting in minimal improvement to the miners' working environment.

[0004] Therefore, this invention is proposed. Summary of the Invention

[0005] In view of the problems existing in the background technology, this application provides a mine water separation and crystallization system and method based on the utilization of waste heat from transcritical CO2 circulation. It can realize the cascade utilization of the thermal energy of supercritical CO2 fluid and the recovery of salt resources in the transcritical CO2 refrigeration module, reduce the cost of mine water resource utilization, and at the same time achieve the cooling of supercritical CO2 fluid, reduce the energy consumed by the transcritical CO2 refrigeration module itself to lower the temperature of supercritical CO2 fluid, and effectively complete the heat hazard control through the transcritical CO2 refrigeration module.

[0006] According to one aspect of the present invention, a mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization is provided, comprising a transcritical CO2 refrigeration module, a sodium chloride brine separation and crystallization module, a sodium sulfate brine separation and crystallization module, a mother liquor drying module, and a steam-assisted heat source module; the transcritical CO2 refrigeration module outputs supercritical CO2 fluid as a heat source to provide energy for sequentially heating the sodium chloride solution in the sodium chloride brine separation and crystallization module and the sodium sulfate solution in the sodium sulfate brine separation and crystallization module to the flash evaporation temperature, and the cooled supercritical CO2 fluid is returned to the transcritical CO2 refrigeration module; the sodium chloride brine... Both the water separation crystallization module and the sodium sulfate brine separation crystallization module adopt forced circulation evaporation crystallization and share a supercritical CO2 fluid heat source for cascade utilization. The steam-assisted heat source module is used to supplement the heat supply to the sodium chloride brine separation crystallization module and the sodium sulfate brine separation crystallization module when the supercritical CO2 fluid heat is insufficient, or to independently heat the sodium chloride brine separation crystallization module and the sodium sulfate brine separation crystallization module. The mother liquor drying module is used to dry the sodium chloride mother liquor and the sodium sulfate mother liquor after the crystallization separation of sodium chloride and sodium sulfate solutions.

[0007] In some embodiments of the present invention, the sodium chloride brine separation and crystallization module adopts a single-effect or countercurrent multi-effect forced circulation evaporation and crystallization module.

[0008] Preferably, the countercurrent multi-effect forced circulation evaporation crystallization module includes a first-effect evaporation unit, a second-effect evaporation unit, and a third-effect evaporation unit. Sodium chloride solution sequentially enters the third-effect evaporation unit, the second-effect evaporation unit, and the first-effect evaporation unit. The first-effect evaporation unit is heated by a supercritical CO2 fluid and / or steam auxiliary heat source module. The second-effect evaporation unit is heated by the first-effect secondary steam of the first-effect evaporation unit. The third-effect evaporation unit is heated by the second-effect secondary steam of the second-effect evaporation unit.

[0009] In some embodiments of the present invention, the operating parameters of the first-effect evaporation unit are 80-90°C, the operating parameters of the second-effect evaporation unit are 60-70°C, and the operating parameters of the third-effect evaporation unit are 40-50°C.

[0010] In some embodiments of the present invention, the sodium sulfate brine separation and crystallization module adopts a single-effect or co-current multi-effect forced circulation evaporation and crystallization module.

[0011] Preferably, the co-current multi-effect forced circulation evaporation crystallization module includes a fourth-effect evaporation unit and a fifth-effect evaporation unit. The sodium sulfate solution enters the fourth-effect evaporation unit and the fifth-effect evaporation unit in sequence. The fourth-effect evaporation unit is heated by a supercritical CO2 fluid and / or steam auxiliary heat source module, and the fifth-effect evaporation unit is heated by the fourth-effect secondary steam of the fourth-effect evaporation unit.

[0012] In some embodiments of the present invention, the operating parameters of the fourth-effect evaporation unit are 50-80°C, and the operating parameters of the fifth-effect evaporation unit are 40-70°C.

[0013] In some embodiments of the present invention, the supercritical CO2 fluid output by the transcritical CO2 refrigeration module has a temperature of 80-120°C and a pressure of 6.5-9 MPa; the industrial steam output by the steam-assisted heat source module has a temperature of 120-150°C and a pressure of 0.2-0.5 MPa.

[0014] In some embodiments of the present invention, the mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization further includes a vacuum module, which is used to form a vacuum system for the sodium chloride brine separation and crystallization module and the sodium sulfate brine separation and crystallization module.

[0015] In some embodiments of the present invention, the transcritical CO2 refrigeration module includes a compressor, a gas cooler, an expansion valve, and an evaporator, and the sodium chloride brine separation and crystallization module and the sodium sulfate brine separation and crystallization module sequentially extract heat between the compressor and the gas cooler.

[0016] According to another aspect of the present invention, a method for separating and crystallizing mine water using the above-described mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization is provided, comprising the following steps: (1) Supercritical CO2 fluid is introduced into the sodium chloride brine separation and crystallization module, and when the heat of the supercritical CO2 fluid is insufficient, industrial steam is output from the steam-assisted heat source module and introduced into the sodium chloride brine separation and crystallization module.

[0017] (2) Sodium chloride solution is evaporated and crystallized. After the supercritical CO2 fluid is cooled, it enters the sodium sulfate brine separation and crystallization module. When the supercritical CO2 fluid is not hot enough, industrial steam is output from the steam auxiliary heat source module and fed into the sodium sulfate brine separation and crystallization module.

[0018] (3) After the sodium sulfate solution is evaporated and crystallized, the supercritical CO2 fluid is further cooled and returned to the transcritical CO2 refrigeration module.

[0019] In some embodiments of the present invention, the start and stop of the steam-assisted heat source module are automatically controlled by monitoring the flash temperature of the sodium sulfate brine separation and crystallization module.

[0020] Compared with the prior art, the present invention achieves the following technical effects: (1) In terms of energy utilization, the present invention utilizes the waste heat of the transcritical CO2 refrigeration module at 80-120℃ in stages to first supply sodium chloride triple-effect countercurrent evaporation (the first effect is 80-90℃), and then supplies sodium sulfate double-effect cocurrent evaporation (the first effect is 50-80℃). Compared with the traditional process, steam consumption is reduced by more than 50%, and thermal efficiency is increased by 65%.

[0021] (2) In terms of process innovation, the sodium chloride brine separation and crystallization module of this invention adopts a countercurrent triple-effect design of "low temperature high concentration - high temperature low concentration" and is combined with forced circulation to effectively inhibit scaling; the sodium sulfate brine separation and crystallization module avoids the precipitation of decahydrate through "co-current double effect + low temperature operation", and the purity of the crystallized product reaches more than 99.2%.

[0022] (3) The system of this invention can simultaneously produce industrial-grade NaCl and anhydrous Na2SO4, with a mine water resource utilization rate of over 90%, and the mother liquor is dried to achieve near-zero discharge.

[0023] (4) Significant economic and environmental benefits. The modular design of this invention reduces equipment investment by 25%, saves 40% on operating costs, and the annual revenue from salt products can cover the system operating costs. It not only replaces ozone-destructive refrigerants, but also solves the problems of mine heat and water hazards, and reduces CO2 emissions by more than 30%.

[0024] The reliability of the mine water separation and crystallization system of the present invention is ensured by the design of automatic switching between dual heat sources, forced circulation anti-scaling, and intelligent temperature control, which can achieve continuous and stable operation throughout the year. The technology of the present invention provides mines with an innovative solution for mine water treatment that is energy-saving, environmentally friendly, resource-recycling, and economically efficient. Attached Figure Description

[0025] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This invention relates to a mine water separation and crystallization system based on the utilization of waste heat from a transcritical CO2 cycle, and a diagram showing the path of CO2 circulation, brine treatment, and thermal coupling.

[0026] Figure 2 This is a schematic diagram of the mine water separation and crystallization system and process based on the utilization of transcritical CO2 cycle waste heat in this invention.

[0027] The labels in the attached diagram are as follows: 1. Transcritical CO2 refrigeration module; 2. Sodium chloride brine separation and crystallization module; 3. Sodium sulfate brine separation and crystallization module; 4. Vacuum pumping module; 5. Steam-assisted heat source module; 6. Mother liquor drying module; 7. First CO2 heat extraction equipment; 22. Second CO2 heat extraction equipment; 81. First steam heater; 82. Second steam heater; 83. Third steam heater; 231. Fourth steam heater; 232. Fifth steam heater; 91. First flash separator; 92. Second flash separator; 93. Third flash separator; 241. Fourth flash separator; 242. Fifth flash separator; 10. First condenser; 25. Second condenser; 111. First forced circulation pump; 112. Second forced circulation pump; 113. Third forced circulation pump; 261. Fourth forced circulation pump; 262. Fifth forced circulation pump; 121. First feed pump; 122. Second feed pump; 123. Third feed pump; 271. Fourth feed pump; 272. Fifth feed pump; 131. First steam condensate tank; 132. Second steam condensate tank; 281. Third steam condensate tank; 282. Fourth steam condensate tank; 14. First vacuum system; 29. ​​Second vacuum system; 15. First raw water preheater; 30. Second raw water preheater; 16. First CO2 heat extraction equipment circulation pump; 31. Second CO2 heat extraction equipment circulation pump; 17. First discharge pump; 32. Second discharge pump; 18. First thickener; 33. Second thickener; 19. First centrifuge; 34. Second centrifuge; 20. First mother liquor tank; 35. Second mother liquor tank; 21. First mother liquor pump; 36. Second mother liquor pump; 371. First valve; 372. Second valve; 373. Third valve; 374. Fourth valve. Detailed Implementation

[0028] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0029] In the following description, when referring to the accompanying drawings, the same numbers in different drawings denote the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0030] In the description of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, in the description of this application, unless otherwise stated, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship.

[0031] The following description, in conjunction with the accompanying drawings, illustrates the mine water separation and crystallization system and method based on transcritical CO2 cycle waste heat utilization provided in the embodiments of this application.

[0032] This application discloses a mine water separation and crystallization system based on the utilization of waste heat from a transcritical CO2 cycle. For example... Figure 1 and Figure 2 As shown, the mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization includes a transcritical CO2 refrigeration module 1, a sodium chloride brine separation and crystallization module 2, a sodium sulfate brine separation and crystallization module 3, a mother liquor drying module 6, and a steam-assisted heat source module 5.

[0033] The transcritical CO2 refrigeration module 1 outputs supercritical CO2 fluid as a heat source to provide energy for heating the sodium chloride solution in the sodium chloride brine separation and crystallization module 2 and the sodium sulfate solution in the sodium sulfate brine separation and crystallization module 3 to the flash evaporation temperature. The cooled supercritical CO2 fluid is returned to the transcritical CO2 refrigeration module 1. Both the sodium chloride brine separation and crystallization module 2 and the sodium sulfate brine separation and crystallization module 3 adopt forced circulation evaporation crystallization modules and share the supercritical CO2 fluid heat source for cascade utilization.

[0034] The steam-assisted heat source module 5 is used to supplement the heat supply to the sodium chloride brine separation and crystallization module 2 and the sodium sulfate brine separation and crystallization module 3 when the heat of the supercritical CO2 fluid is insufficient, or to independently supply heat to the sodium chloride brine separation and crystallization module 2 and the sodium sulfate brine separation and crystallization module 3 using the steam-assisted heat source module 5; the mother liquor drying module 6 is used to dry the sodium chloride mother liquor and the sodium sulfate mother liquor after the crystallization and separation of sodium chloride and sodium sulfate materials.

[0035] In this invention, the transcritical CO2 refrigeration module 1 can output high-temperature, high-pressure supercritical CO2 fluid as a heat source. Utilizing the property that the flash evaporation starting temperature of sodium sulfate is lower than that of sodium chloride at the same concentration, the high-temperature, high-pressure supercritical CO2 fluid first provides energy to raise the temperature of the sodium chloride solution in the sodium chloride brine separation and crystallization module 2 to the flash evaporation temperature. At the same time, the temperature of the high-temperature, high-pressure supercritical CO2 fluid decreases. Then, the high-temperature, high-pressure supercritical CO2 fluid provides energy to raise the temperature of the sodium sulfate solution in the sodium sulfate brine separation and crystallization module 3 to the flash evaporation temperature. At the same time, the temperature of the high-temperature, high-pressure supercritical CO2 fluid decreases further. Afterward, the high-temperature, high-pressure supercritical CO2 fluid flows back to the transcritical CO2 refrigeration module 1 to further reduce the temperature. Subsequently, the transcritical CO2 refrigeration module 1 can provide liquid CO2 at a temperature of 0-5℃ downhole, reducing the underground ambient temperature to below 20℃, improving the health of miners, and improving production efficiency. Moreover, while the transcritical CO2 refrigeration module 1 is refrigerating, it generates high-grade waste heat of approximately 120℃ (80-120℃), which is then circulated and output as a heat source using the high-temperature, high-pressure supercritical CO2 fluid.

[0036] Meanwhile, the sodium chloride brine separation and crystallization module 2, after heating the sodium chloride solution to the flash evaporation temperature using supercritical CO2 fluid, can obtain sodium chloride crystals and sodium chloride mother liquor through evaporation, thickening, and centrifugation. The sodium sulfate brine separation and crystallization module 3, after heating the sodium sulfate solution to the flash evaporation temperature using supercritical CO2 fluid, can obtain sodium sulfate crystals and sodium sulfate mother liquor through evaporation, thickening, and centrifugation. Then, the sodium chloride mother liquor and sodium sulfate mother liquor can be mixed and fed into the mother liquor drying module 6 for drying treatment, converting the mother liquor into a solid and achieving "zero discharge" of wastewater.

[0037] By using the mine water separation and crystallization system in this technical solution, the supercritical CO2 fluid thermal energy utilization and salt resource recovery in the transcritical CO2 refrigeration module 1 are realized, reducing the cost of mine water resource utilization. At the same time, the supercritical CO2 fluid is cooled, reducing the energy (such as electrical energy) consumed by the transcritical CO2 refrigeration module itself to lower the temperature of the supercritical CO2 fluid. Finally, the heat hazard is effectively controlled through the transcritical CO2 refrigeration module.

[0038] This invention integrates a transcritical CO2 refrigeration module 1 with mine water treatment, employing green and energy-saving technologies to address the problem of mine water resource utilization. It can lead the industry's energy and resource transformation. This invention uses supercritical CO2 waste heat to overcome the technical bottleneck of low-cost mine water resource utilization, achieving innovation in new technologies and models. It solves a series of problems such as extremely high energy consumption, large land area, and low thermal energy utilization rate in the end-stage processes of mine water treatment, laying the foundation for the coordinated management and large-scale promotion of underground heat and water hazards, and filling the gap in green technology for mine water treatment.

[0039] It should also be noted that the supercritical CO2 fluid and steam-assisted heat source module 5 of the present invention can be used as a heat source alone or simultaneously. For example, depending on the working conditions, the supercritical CO2 fluid, the steam-assisted heat source module 5, or both can be used to heat the sodium chloride brine separation and crystallization module 2 and the sodium sulfate brine separation and crystallization module 3. For example, when the supercritical CO2 fluid is insufficient for heating, the steam-assisted heat source module 5 can supplement the heating of the sodium chloride brine separation and crystallization module 2 and the sodium sulfate brine separation and crystallization module 3, and the two work together.

[0040] In some embodiments of the present invention, such as Figure 2 As shown, the sodium chloride brine separation and crystallization module 2 adopts a single-effect or countercurrent multi-effect forced circulation evaporation and crystallization module.

[0041] Furthermore, the countercurrent multi-effect forced circulation evaporation crystallization module can be a countercurrent double-effect process, a countercurrent triple-effect process, or a countercurrent quadruple-effect process, with the countercurrent triple-effect process being preferred.

[0042] In some embodiments of the present invention, such as Figure 2 As shown, the countercurrent multi-effect forced circulation evaporation crystallization module is a countercurrent three-effect process. The countercurrent multi-effect forced circulation evaporation crystallization module includes a first-effect evaporation unit, a second-effect evaporation unit, and a third-effect evaporation unit. Sodium chloride solution enters the third-effect evaporation unit, the second-effect evaporation unit, and the first-effect evaporation unit in sequence. The first-effect evaporation unit is heated by a supercritical CO2 fluid and / or steam auxiliary heat source module 5. The second-effect evaporation unit is heated by the first-effect secondary steam of the first-effect evaporation unit. The third-effect evaporation unit is heated by the second-effect secondary steam of the second-effect evaporation unit.

[0043] It should be understood that when the sodium chloride brine separation and crystallization module 2 adopts a single-effect forced circulation evaporation and crystallization module, it can be equipped with only one evaporation unit. This evaporation unit is directly heated by the supercritical CO2 fluid and / or steam auxiliary heat source module 5, and the sodium chloride solution is directly flash-evaporated in this evaporation unit. When the sodium chloride brine separation and crystallization module 2 adopts other forced circulation evaporation and crystallization modules such as countercurrent double-effect, quadruple-effect or more, the sodium chloride solution enters each evaporation unit sequentially from back to front for flash evaporation until the final concentration is completed in the first-effect evaporation unit. At the same time, only the first-effect evaporation unit is directly heated by the supercritical CO2 fluid and / or steam auxiliary heat source module 5, and the subsequent evaporation units are all heated by the secondary steam of the previous effect.

[0044] Meanwhile, it is understandable that when the sodium chloride brine separation and crystallization module 2 adopts a single-effect forced circulation evaporation and crystallization module, the structure of one of its evaporation units can simultaneously or separately utilize the thermal energy of supercritical CO2 fluid and industrial steam; when the sodium chloride brine separation and crystallization module 2 adopts a countercurrent multi-effect forced circulation evaporation and crystallization module, only the structure of its first-effect evaporation unit can simultaneously or separately utilize the thermal energy of supercritical CO2 fluid and industrial steam, and the structures of other evaporation units only need to be able to utilize the secondary steam from the previous effect for heating.

[0045] In some embodiments of the present invention, such as Figure 2 As shown, the sodium chloride brine separation and crystallization module 2 includes a first-effect evaporation unit, a second-effect evaporation unit, and a third-effect evaporation unit.

[0046] The third-effect evaporation unit includes a third steam heater 83, a third flash separator 93, and a third forced circulation pump 113. The feed chamber of the third steam heater 83 is connected in series with the third flash separator 93 through the third forced circulation pump 113, and the sodium chloride water tank is connected to the third flash separator 93 through the third feed pump 123.

[0047] The second-effect evaporation unit includes a second steam heater 82, a second flash separator 92, and a second forced circulation pump 112. The feed chamber of the second steam heater 82 is connected in series with the second flash separator 92 through the second forced circulation pump 112. The third flash separator 93 is connected to the second flash separator 92 through the second feed pump 122.

[0048] The first-effect evaporation unit includes a first steam heater 81, a first flash separator 91, a first forced circulation pump 111, a first CO2 heat extraction device 7, and a first CO2 heat extraction device circulation pump 16. The feed chamber of the first steam heater 81 is connected in series with the first flash separator 91 through the first forced circulation pump 111, and the feed chamber of the first CO2 heat extraction device 7 is connected in series with the first flash separator 91 through the first CO2 heat extraction device circulation pump 16. The second flash separator 92 is connected to the first flash separator 91 through the first feed pump 121. Specifically, the first feed pump 121 is connected to the pipeline between the first forced circulation pump 111 and the first steam heater 81.

[0049] The supercritical CO2 fluid chamber of the first CO2 heat extraction equipment 7 is connected in series to the transcritical CO2 refrigeration module 1. The gas chamber inlet of the first steam heater 81 is connected to the steam auxiliary heat source module 5. The top outlet of the first flash separator 91 is connected to the gas chamber inlet of the second steam heater 82. The top outlet of the second flash separator 92 is connected to the gas chamber inlet of the third steam heater 83.

[0050] Furthermore, the sodium chloride brine separation and crystallization module 2 also includes a first discharge pump 17, a first thickener 18, a first centrifuge 19, a first mother liquor tank 20, and a first mother liquor pump 21. The first thickener 18, the first centrifuge 19, and the first mother liquor tank 20 are connected sequentially. The first discharge pump 17 is connected to the first flash separator 91 and the first thickener 18. The first mother liquor pump 21 is connected to the first mother liquor tank 20 and the mother liquor drying module 6, and simultaneously to the first mother liquor tank 20 and the first flash separator 91. Specifically, the first mother liquor pump 21 is connected to the inlet of the first forced circulation pump 111.

[0051] Furthermore, the first discharge pump 17 is also connected to the side wall of the first flash separator 91 and the bottom of the first flash separator 91, and the first discharge pump 17 can feed material from the side wall of the first flash separator 91 to the bottom of the first flash separator 91.

[0052] In some embodiments of the present invention, such as Figure 2 As shown, the sodium chloride brine separation and crystallization module 2 also includes a first raw water preheater 15, a first steam condensate tank 131, a second steam condensate tank 132, and a first condenser 10. One chamber of the first condenser 10 is supplied with circulating water, and the other chamber is connected to the gas outlets of the first steam heater 81, the second steam heater 82, and the third steam heater 83. The first steam condensate tank 131 is connected to the gas chamber of the first steam heater 81 to receive condensate. The second steam condensate tank 132 is connected to the gas chambers of the second steam heater 82 and the third steam heater 83, as well as the gas chamber of the first condenser 10, to receive condensate. One chamber of the first raw water preheater 15 is connected between the third feed pump 123 and the third flash separator 93, and the other chamber supplies hot water through the first steam condensate tank 131 and / or the second steam condensate tank 132.

[0053] In some embodiments of the present invention, such as Figure 2 As shown, the top outlet of the first flash separator 91 is also connected to the gas chamber of the first condenser 10. A first valve 371 is provided between the first flash separator 91 and the first condenser 10, and a second valve 372 is provided between the first flash separator 91 and the second steam heater 82.

[0054] In this embodiment, by controlling the opening of the first valve 371, the secondary steam from the first flash separator 91 can enter the first condenser 10. By controlling the opening of the second valve 372, the secondary steam from the first flash separator 91 can enter the second steam heater 82. Thus, the countercurrent multi-effect forced circulation evaporation crystallization module can be used to complete both countercurrent multi-effect and single-effect processes. That is, by setting the first valve 371 and the second valve 372, the present invention can realize the switching between single-effect and countercurrent multi-effect processes.

[0055] Specifically, when a single-effect process is used, the first valve 371 can be opened and the second valve 372 can be closed, so that the secondary steam of the first flash separator 91 only enters the first condenser 10, and the second steam heater 82 is in a non-heat exchange state. That is, there is no significant temperature change of the sodium chloride liquid before and after passing through the second steam heater 82, thereby realizing a single-effect process in which the sodium chloride liquid is evaporated only by the first flash separator 91.

[0056] When using a countercurrent multi-effect process, the first valve 371 can be closed and the second valve 372 opened, so that the secondary steam from the first flash separator 91 only enters the second steam heater 82. That is, the sodium chloride solution undergoes a significant temperature change before and after passing through the second steam heater 82. Then, the secondary steam from the second flash separator 92 enters the third steam heater 83. That is, the sodium chloride solution also undergoes a significant temperature change before and after passing through the third steam heater 83. Thus, the countercurrent multi-effect process of the sodium chloride solution is completed sequentially by the third flash separator 93, the second flash separator 92, and the first flash separator 91. The solution is then pumped into the pre-effect stage for progressive concentration via an inter-effect forced circulation pump.

[0057] In some embodiments of the present invention, the operating parameters of the first-effect evaporation unit are 80-90°C, the operating parameters of the second-effect evaporation unit are 60-70°C, and the operating parameters of the third-effect evaporation unit are 40-50°C.

[0058] In some embodiments of the present invention, such as Figure 2 As shown, the sodium sulfate brine separation and crystallization module 3 adopts a single-effect or co-current multi-effect forced circulation evaporation and crystallization module.

[0059] Furthermore, the co-current multi-effect forced circulation evaporation crystallization module can be a co-current two-effect process, a co-current three-effect process, or a co-current four-effect process, with a co-current two-effect process being preferred.

[0060] In some embodiments of the present invention, such as Figure 2 As shown, the co-current multi-effect forced circulation evaporation crystallization module is a co-current two-effect process. The co-current multi-effect forced circulation evaporation crystallization module includes a fourth-effect evaporation unit and a fifth-effect evaporation unit. The sodium sulfate solution enters the fourth-effect evaporation unit and the fifth-effect evaporation unit in sequence. The fourth-effect evaporation unit is heated by a supercritical CO2 fluid and / or steam auxiliary heat source module, and the fifth-effect evaporation unit is heated by the fourth-effect secondary steam of the fourth-effect evaporation unit.

[0061] It should be understood that when the sodium sulfate brine separation and crystallization module 3 adopts a single-effect forced circulation evaporation and crystallization module, it can be equipped with only one evaporation unit. This evaporation unit is directly heated by the supercritical CO2 fluid and / or steam auxiliary heat source module 5, and the sodium sulfate solution is directly flash-evaporated in this evaporation unit. When the sodium sulfate brine separation and crystallization module 3 adopts other forced circulation evaporation and crystallization modules such as co-current two-effect, four-effect or more-effect modules, the sodium sulfate solution enters each evaporation unit sequentially from front to back for flash evaporation until the final concentration is completed in the last evaporation unit. At the same time, only the first-effect evaporation unit is directly heated by the supercritical CO2 fluid and / or steam auxiliary heat source module 5, and the subsequent evaporation units are all heated by the secondary steam of the previous effect.

[0062] Meanwhile, it is understandable that when the sodium sulfate brine separation and crystallization module 3 adopts a single-effect forced circulation evaporation and crystallization module, the structure of one of its evaporation units can simultaneously or separately utilize the thermal energy of supercritical CO2 fluid and industrial steam; when the sodium sulfate brine separation and crystallization module 3 adopts a co-current multi-effect forced circulation evaporation and crystallization module, only the structure of its first-effect evaporation unit can simultaneously or separately utilize the thermal energy of supercritical CO2 fluid and industrial steam, and the structures of other evaporation units only need to be able to utilize the secondary steam from the previous effect for heating.

[0063] In some embodiments of the present invention, such as Figure 2 As shown, the sodium sulfate brine separation and crystallization module 3 includes a fourth-effect evaporation unit and a fifth-effect evaporation unit.

[0064] The fourth-effect evaporation unit includes a fourth steam heater 231, a fourth flash separator 241, a fourth forced circulation pump 261, a second CO2 heat extraction device 22, and a second CO2 heat extraction device circulation pump 31. The feed chamber of the fourth steam heater 231 is connected in series with the fourth flash separator 241 through the fourth forced circulation pump 261, and the feed chamber of the second CO2 heat extraction device 22 is connected in series with the fourth flash separator 241 through the second CO2 heat extraction device circulation pump 31. The sodium sulfate water tank is connected to the fourth flash separator 241 through the fourth feed pump 271.

[0065] The fifth-effect evaporation unit includes a fifth steam heater 232, a fifth flash separator 242 and a fifth forced circulation pump 262. The feed chamber of the fifth steam heater 232 is connected in series with the fifth flash separator 242 through the fifth forced circulation pump 262. The fourth flash separator 241 is connected to the fifth flash separator 242 through the fifth feed pump 272.

[0066] The supercritical CO2 fluid chamber of the second CO2 heat extraction device 22 is connected in series to the transcritical CO2 refrigeration module 1, and the second CO2 heat extraction device 22 is located downstream of the first CO2 heat extraction device 7. The gas chamber inlet of the fourth steam heater 231 is connected to the steam auxiliary heat source module 5, and the top outlet of the fourth flash separator 241 is connected to the gas chamber inlet of the fifth steam heater 232.

[0067] Furthermore, the sodium sulfate brine separation and crystallization module 3 also includes a second discharge pump 32, a second thickener 33, a second centrifuge 34, a second mother liquor tank 35, and a second mother liquor pump 36. The second thickener 33, the second centrifuge 34, and the second mother liquor tank 35 are connected sequentially. The second discharge pump 32 is connected to the fifth flash separator 242 and the second thickener 33. The second mother liquor pump 36 is connected to the second mother liquor tank 35 and the mother liquor drying module 6, and simultaneously to the second mother liquor tank 35 and the fifth flash separator 242. Specifically, the second mother liquor pump 36 is connected to the inlet of the fifth forced circulation pump 262.

[0068] Furthermore, the second discharge pump 32 is also connected to the side wall of the fifth flash separator 242 and the bottom of the fifth flash separator 242. The second discharge pump 32 can feed material from the side wall of the fifth flash separator 242 to the bottom of the fifth flash separator 242.

[0069] In some embodiments of the present invention, such as Figure 2 As shown, the sodium sulfate brine separation and crystallization module 3 also includes a second raw water preheater 30, a third steam condensate tank 281, a fourth steam condensate tank 282, and a second condenser 25. One chamber of the second condenser 25 is supplied with circulating water, and the other chamber is connected to the gas outlets of both the fourth steam heater 231 and the fifth steam heater 232. The third steam condensate tank 281 is connected to the gas chamber of the fourth steam heater 231 to receive condensate, and the fourth steam condensate tank 282 is connected to the gas chamber of the fifth steam heater 232 and the gas chamber of the second condenser 25 to receive condensate. One chamber of the second raw water preheater 30 is connected between the fourth feed pump 271 and the fourth flash separator 241, and the other chamber supplies hot water through the third steam condensate tank 281 and / or the fourth steam condensate tank 282.

[0070] In some embodiments of the present invention, such as Figure 2 As shown, the top outlet of the fourth flash separator 241 is also connected to the gas chamber of the second condenser 25. A third valve 373 is provided between the fourth flash separator 241 and the second condenser 25, and a fourth valve 374 is provided between the fourth flash separator 241 and the fifth steam heater 232.

[0071] In this embodiment, by controlling the opening of the third valve 373, the secondary steam from the fourth flash separator 241 can enter the second condenser 25. By controlling the opening of the fourth valve 374, the secondary steam from the fourth flash separator 241 can enter the fifth steam heater 232. Thus, the co-current multi-effect forced circulation evaporation crystallization module can be used to complete both co-current multi-effect and single-effect processes. That is, by setting the third valve 373 and the fourth valve 374, the present invention can realize the switching between single-effect and co-current multi-effect processes.

[0072] Specifically, when using a single-effect process, the third valve 373 can be opened and the fourth valve 374 can be closed, so that the secondary steam from the fourth flash separator 241 only enters the second condenser 25, and the fifth steam heater 232 is in a non-heat exchange state. That is, there is no significant temperature change of the sodium sulfate solution before and after passing through the fifth steam heater 232, thereby realizing a single-effect process in which the sodium sulfate solution is evaporated only by the fourth flash separator 241.

[0073] When using a co-current multi-effect process, the third valve 373 can be closed and the fourth valve 374 can be opened, so that the secondary steam from the fourth flash separator 241 only enters the fifth steam heater 232. That is, the sodium sulfate solution undergoes a significant temperature change before and after passing through the fifth steam heater 232, thereby realizing the co-current multi-effect process of the sodium sulfate solution by the fourth flash separator 241 and the fifth flash separator 242 in sequence. The solution is then pumped into the subsequent effects for step-by-step concentration by a forced circulation pump between the effects.

[0074] In some embodiments of the present invention, the operating parameters of the fourth-effect evaporation unit are 50-80°C, and the operating parameters of the fifth-effect evaporation unit are 40-70°C.

[0075] In some embodiments of the present invention, the supercritical CO2 fluid output by the transcritical CO2 refrigeration module 1 has a temperature of 80-120°C and a pressure of 6.5-9 MPa; the industrial steam output by the steam-assisted heat source module 5 has a temperature of 120-150°C and a pressure of 0.2-0.5 MPa.

[0076] In the mine water separation and crystallization system of the present invention, when the sodium chloride brine separation and crystallization module 2 adopts a counter-current triple-effect forced circulation evaporation and crystallization module and the sodium sulfate brine separation and crystallization module 3 adopts a co-current double-effect forced circulation evaporation and crystallization module, the first effect heat source of the sodium chloride brine separation and crystallization module 2 is 80-120℃ supercritical CO2, and the second and third effects utilize the secondary steam from the previous effect respectively; the first effect heat source of the sodium sulfate brine separation and crystallization module 3 is 60-90℃ supercritical CO2 after the sodium chloride brine separation and crystallization module has been cooled, and the second effect utilizes the secondary steam from the first effect.

[0077] In some embodiments of the present invention, the first CO2 heat extraction device 7 and the second CO2 heat extraction device 22 may respectively adopt shell-and-tube or heat pipe heat exchangers.

[0078] In some embodiments of the present invention, industrial steam is used as the heat source for drying the mother liquor, and an indirect steam heating method is adopted, with the processing temperature controlled at 120-150°C.

[0079] In some embodiments of the present invention, the mother liquor drying module 6 includes a mixed salt raw material tank, a mixed salt feed pump, a dryer, an induced draft fan, a tail gas scrubbing tower, a scrubbing tower circulation pump, etc.

[0080] The raw materials for the mixed salt raw material tank come from the mother liquor of sodium chloride brine separation and crystallization module 2 and sodium sulfate brine separation and crystallization module 3.

[0081] In some embodiments of the present invention, the mother liquor drying module 6 may be a skid-mounted structure to process the mixed mother liquor from the sodium chloride brine separation and crystallization module 2 and the sodium sulfate brine separation and crystallization module 3.

[0082] In some embodiments of the present invention, such as Figure 1 and Figure 2 As shown, the mine water separation and crystallization system also includes a vacuum module 4, which is used to form a vacuum system for the sodium chloride brine separation and crystallization module 2 and the sodium sulfate brine separation and crystallization module 3.

[0083] In some embodiments of the present invention, such as Figure 2 As shown, the vacuum module 4 includes a first vacuum system 14 and a second vacuum system 29.

[0084] In one embodiment of the present invention, the first vacuum system 14 is connected to the second steam condensate tank 132, and the second vacuum system 29 is connected to the fourth steam condensate tank 282.

[0085] Furthermore, the first vacuum system 14 and the second vacuum system 29 may each include structures such as a vacuum pump assembly.

[0086] In some embodiments of the present invention, the start and stop of the steam-assisted heat source module 5 are automatically controlled by monitoring the flash evaporation temperature of the sodium sulfate brine separation and crystallization module 3.

[0087] In one embodiment of the present invention, the activation of the auxiliary heat source is determined by the temperature display of the fourth flash separator 241.

[0088] In some embodiments of the present invention, the transcritical CO2 refrigeration module 1 includes a compressor, a gas cooler (waste heat release end), an expansion valve, and an evaporator (downhole refrigeration end), and the sodium chloride brine separation and crystallization module 2 and the sodium sulfate brine separation and crystallization module 3 sequentially extract heat between the compressor and the gas cooler.

[0089] In some embodiments of the present invention, such as Figure 2 As shown, the supercritical CO2 fluid chamber of the first CO2 heat extraction device 7 and the supercritical CO2 fluid chamber of the second CO2 heat extraction device 22 are sequentially connected between the compressor and the gas cooler.

[0090] In this embodiment, the compressor outputs 120°C supercritical CO2 fluid as a heat source. It first enters the first CO2 heat extraction equipment 7 and is heated. Then, after the supercritical CO2 fluid exits from the first CO2 heat extraction equipment 7, it continues to enter the second CO2 heat extraction equipment 22 and is heated. After that, the supercritical CO2 fluid exits from the second CO2 heat extraction equipment 22 and enters the gas cooler to release residual heat. Finally, the CO2 passes through the expansion valve and evaporator to complete the underground cooling, thereby realizing the cascade utilization of thermal energy and the recovery of salt resources, and reducing the cost of mine water resource utilization.

[0091] In some embodiments of the present invention, the steam-assisted heat source module 5 includes industrial steam pipes, control valves, etc., to supplement heat supply when CO2 heat is insufficient.

[0092] This embodiment also proposes a method for separating and crystallizing mine water using the above-mentioned mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization, including the following steps: (1) Supercritical CO2 fluid is introduced into sodium chloride brine separation and crystallization module 2, and when the heat of supercritical CO2 fluid is insufficient, industrial steam is output from steam auxiliary heat source module 5 and introduced into sodium chloride brine separation and crystallization module 2.

[0093] (2) The sodium chloride solution is evaporated and crystallized. After the supercritical CO2 fluid is cooled, it enters the sodium sulfate brine separation and crystallization module 3. When the supercritical CO2 fluid is not hot enough, industrial steam is output from the steam auxiliary heat source module 5 and introduced into the sodium sulfate brine separation and crystallization module 3.

[0094] (3) The sodium sulfate solution is evaporated and crystallized, and the supercritical CO2 fluid is further cooled and returned to the transcritical CO2 refrigeration module 1.

[0095] In some embodiments of the present invention, in the mine water separation and crystallization system, the sodium chloride brine separation and crystallization module 2 is a countercurrent triple-effect forced circulation evaporation and crystallization module, and the sodium sulfate brine separation and crystallization module 3 is a co-current double-effect forced circulation evaporation and crystallization module. The mine water separation and crystallization method includes the following steps: (1) Supercritical CO2 at 80-120℃ is introduced into the first CO2 heat extraction equipment 7 of sodium chloride brine separation and crystallization module 2.

[0096] (2) The sodium chloride solution is evaporated and crystallized by countercurrent triple-effect evaporation. After the CO2 temperature is reduced to 60-90℃, it enters the second CO2 heat extraction equipment 22 of the sodium sulfate brine separation and crystallization module 3.

[0097] (3) The sodium sulfate solution is evaporated and crystallized in a co-current two-effect manner, and the CO2 is further cooled to 50-80℃ and returned to the transcritical CO2 refrigeration module 1.

[0098] (4) When CO2 heat is insufficient, industrial steam is used to supplement the heating.

[0099] Furthermore, the first-effect temperature of sodium chloride crystallization is controlled at 80-90℃ to prioritize the utilization of CO2 waste heat; the first-effect temperature of sodium sulfate crystallization is controlled at 50-80℃ to prevent the precipitation of sodium sulfate decahydrate.

[0100] By using the mine water separation and crystallization system of the present invention, the sodium chloride brine separation and crystallization module 2 adopts a counter-current triple-effect process to reduce steam consumption by more than 50%; the sodium sulfate brine separation and crystallization module 3 adopts a co-current double-effect process to reduce steam consumption by more than 30%.

[0101] In some embodiments of the present invention, the start and stop of the steam auxiliary heat source module can be automatically controlled by monitoring the flash temperature of the sodium sulfate brine separation and crystallization module 2, and preferably the auxiliary heat source can be activated by displaying the temperature of the fourth flash separator 241.

[0102] The following will describe the mine water separation and crystallization method based on the utilization of waste heat from transcritical CO2 cycles, with specific embodiments.

[0103] Example 1 1) The 80-120℃, 6.5-9MPa supercritical CO2 discharged from the transcritical CO2 refrigeration module 1 enters the first CO2 heat extraction equipment 7 of the sodium chloride brine separation and crystallization module 2, heating the first-effect sodium chloride circulating solution, and its own temperature drops to 60-90℃.

[0104] 2) When CO2 heat is insufficient, industrial steam at 120-150℃ and 0.2-0.5MPa is used to heat part of the sodium chloride circulating solution through the first steam heater 81, so that its temperature reaches the inlet temperature of the first flash separator 91.

[0105] 3) In the sodium chloride triple-effect countercurrent forced circulation evaporation and crystallization process, the feed liquid first enters the first raw material water preheater 15 for preheating, and then enters the third steam heater 83 (40-50℃). The heat source of the first raw material water preheater 15 comes from the first steam condensate tank 131 and the second steam condensate tank 132. It is heated and initially concentrated by the secondary steam of the second effect. The third forced circulation pump 113 pushes the feed liquid to circulate between the third steam heater 83 and the third flash separator 93. The concentrated liquid enters the second effect (60-70℃) for continued evaporation and is heated by the secondary steam of the first effect. Finally, it enters the first effect (80-90℃) for direct heating by CO2 waste heat / industrial steam to complete the crystallization. The crystal slurry is thickened by the first thickener 18 and then centrifuged by the first centrifuge 19 to obtain NaCl crystals. The mother liquor is partially returned to the inlet of the last forced circulation pump 111 in the material flow direction by the first mother liquor pump 21 for continued evaporation and crystallization, and the remainder enters the mother liquor drying module 6. The final-effect secondary steam is condensed into fresh water by the first condenser 10 and output to the system. This countercurrent process achieves a reasonable match between low-temperature high-concentration and high-temperature low-concentration, and the forced circulation effectively inhibits scaling. The cascade utilization of CO2 waste heat reduces steam consumption by more than 50%.

[0106] 4) The supercritical CO2 (60-90℃, 6.0-8.5MPa) cooled by sodium chloride triple-effect evaporation crystallization enters the second CO2 heat extraction equipment 22 of the sodium sulfate brine separation and crystallization module 3 to heat the sodium sulfate circulating solution of the first effect. After its own temperature drops to 50-80℃, it enters the transcritical CO2 refrigeration module 1 after the above-mentioned step-by-step utilization, and the cycle repeats.

[0107] 5) If the CO2 heat is insufficient, industrial steam at 120-150℃ and 0.2-0.5MPa is used to heat the sodium sulfate circulating solution through the fourth steam heater 231, so that its temperature reaches the inlet temperature of the fourth flash separator 241.

[0108] 6) In the sodium sulfate double-effect co-current forced circulation evaporation and crystallization process, single-effect and multi-effect operation is achieved by switching between the third valve 373 and the fourth valve 374. Taking multi-effect as an example, the feed liquid first enters the second raw water preheater 30 for preheating, and then enters the first effect (50-80℃), where it is directly heated and evaporated by the waste heat of CO2. The fourth forced circulation pump 261 pushes the feed liquid to circulate in the fourth steam heater 231 and the fourth flash separator 241. The concentrated liquid and the precipitated Na2SO4 crystals enter the second effect (40-70℃) together for continued evaporation, and are heated by the secondary steam from the first effect. Finally, the crystal slurry enters the second thickener 33 for thickening, and then enters the second centrifuge 34 to separate and obtain Na2SO4 crystals. The mother liquor is partially returned to the inlet of the forced circulation pump 262 by the second mother liquor pump 36 for continued evaporation and crystallization, controlling the crystal particle size. The remainder enters the mother liquor drying module 6. The secondary steam from the last effect is condensed into fresh water by the second condenser 25 and enters the fourth steam condensate tank 282. This process uses a medium-low temperature heat source of 60-90℃, and effectively prevents the precipitation of sodium sulfate decahydrate through co-current feeding and forced circulation, while realizing the cascade utilization of heat energy and reducing steam consumption by more than 30%.

[0109] 7) The vacuum in the sodium chloride and sodium sulfate evaporation crystallization systems is formed by their respective vacuum systems.

[0110] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization, characterized in that, It includes a transcritical CO2 refrigeration module, a sodium chloride brine separation and crystallization module, a sodium sulfate brine separation and crystallization module, a mother liquor drying module, and a steam-assisted heat source module; The transcritical CO2 refrigeration module outputs supercritical CO2 fluid as a heat source to provide energy for heating the sodium chloride solution in the sodium chloride brine separation and crystallization module and the sodium sulfate solution in the sodium sulfate brine separation and crystallization module to the flash evaporation temperature. The cooled supercritical CO2 fluid is then returned to the transcritical CO2 refrigeration module. Both the sodium chloride brine separation and crystallization module and the sodium sulfate brine separation and crystallization module are forced circulation evaporation crystallization modules and share the supercritical CO2 fluid heat source for cascade utilization. The steam-assisted heat source module is used to supplement the heat supply to the sodium chloride brine separation and crystallization module and the sodium sulfate brine separation and crystallization module when the heat of the supercritical CO2 fluid is insufficient, or to independently supply heat to the sodium chloride brine separation and crystallization module and the sodium sulfate brine separation and crystallization module using the steam-assisted heat source module. The mother liquor drying module is used to dry the sodium chloride mother liquor after crystallization and separation of sodium chloride solution and the sodium sulfate mother liquor after crystallization and separation of sodium sulfate solution.

2. The mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization according to claim 1, characterized in that, The sodium chloride brine separation and crystallization module adopts a single-effect or countercurrent multi-effect forced circulation evaporation and crystallization module. Preferably, the countercurrent multi-effect forced circulation evaporation crystallization module includes a first-effect evaporation unit, a second-effect evaporation unit, and a third-effect evaporation unit. Sodium chloride solution sequentially enters the third-effect evaporation unit, the second-effect evaporation unit, and the first-effect evaporation unit. The first-effect evaporation unit is heated by a supercritical CO2 fluid and / or steam auxiliary heat source module. The second-effect evaporation unit is heated by the first-effect secondary steam of the first-effect evaporation unit. The third-effect evaporation unit is heated by the second-effect secondary steam of the second-effect evaporation unit.

3. The mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization according to claim 2, characterized in that, The operating parameters of the first-effect evaporation unit are 80-90℃, the operating parameters of the second-effect evaporation unit are 60-70℃, and the operating parameters of the third-effect evaporation unit are 40-50℃.

4. The mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization according to claim 1, characterized in that, The sodium sulfate brine separation and crystallization module adopts a single-effect or co-current multi-effect forced circulation evaporation and crystallization module; Preferably, the co-current multi-effect forced circulation evaporation crystallization module includes a fourth-effect evaporation unit and a fifth-effect evaporation unit. The sodium sulfate solution enters the fourth-effect evaporation unit and the fifth-effect evaporation unit in sequence. The fourth-effect evaporation unit is heated by a supercritical CO2 fluid and / or steam auxiliary heat source module, and the fifth-effect evaporation unit is heated by the fourth-effect secondary steam of the fourth-effect evaporation unit.

5. The mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization according to claim 4, characterized in that, The operating parameters of the fourth-effect evaporation unit are 50-80℃, and the operating parameters of the fifth-effect evaporation unit are 40-70℃.

6. The mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization according to claim 1, characterized in that, The transcritical CO2 refrigeration module outputs supercritical CO2 fluid with a temperature of 80-120℃ and a pressure of 6.5-9MPa; the steam-assisted heat source module outputs industrial steam with a temperature of 120-150℃ and a pressure of 0.2-0.5MPa.

7. The mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization according to claim 1, characterized in that, It also includes a vacuum module, which is used to form a vacuum system for the sodium chloride brine separation and crystallization module and the sodium sulfate brine separation and crystallization module.

8. The mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization according to claim 1, characterized in that, The transcritical CO2 refrigeration module includes a compressor, a gas cooler, an expansion valve, and an evaporator. The sodium chloride brine separation and crystallization module and the sodium sulfate brine separation and crystallization module extract heat sequentially between the compressor and the gas cooler.

9. A method for separating and crystallizing mine water using a mine water separation and crystallization system based on transcritical CO2 cycle waste heat utilization as described in any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Supercritical CO2 fluid is introduced into the sodium chloride brine separation and crystallization module, and when the heat of the supercritical CO2 fluid is insufficient, industrial steam is output from the steam-assisted heat source module and introduced into the sodium chloride brine separation and crystallization module. (2) The sodium chloride solution is evaporated and crystallized. After the supercritical CO2 fluid is cooled, it enters the sodium sulfate brine separation and crystallization module. When the supercritical CO2 fluid is not hot enough, industrial steam is output from the steam auxiliary heat source module and fed into the sodium sulfate brine separation and crystallization module. (3) After the sodium sulfate solution is evaporated and crystallized, the supercritical CO2 fluid is further cooled and returned to the transcritical CO2 refrigeration module.

10. The method according to claim 9, characterized in that, In steps (1) and (2), the start and stop of the steam-assisted heat source module are automatically controlled by monitoring the flash temperature of the sodium sulfate brine separation and crystallization module.

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