Process of high-efficiency heat exchange vacuum evaporator for high-concentration brine

Abstract

This invention relates to the field of waste liquid treatment technology and discloses a process for a high-efficiency heat exchange vacuum evaporator for high-concentration brine. The process includes the following specific steps: making the pressure inside the first evaporator and the second evaporator negative; circulating the high-concentration liquid in the first evaporator between the first evaporator heat exchanger and the first evaporator, and exchanging heat with the hot refrigerant; when the monitoring index of the monitoring component reaches a preset threshold, the first concentrate is output to a centrifuge for salt separation. This can achieve the discharge of the high-concentration liquid from the evaporator when it is evaporated to a solid-liquid mixture state, avoiding excessive salt precipitation in the evaporator, which would cause salt to deposit at the bottom of the evaporator and not be discharged smoothly, or adhere to the surface of the heat exchange tubes in the heat exchanger, resulting in a decrease in the contact area between the high-concentration liquid and the refrigerant.

Description

Technical Field

[0001] This invention relates to the field of waste liquid treatment technology, specifically to a process for a high-efficiency heat exchange vacuum evaporator for high-concentration brine. Background Technology

[0002] The boiling point of a medium varies under different pressures. Under low pressure or even vacuum, the boiling point of water decreases, making it easier to evaporate at low temperatures. Evaporators are devices based on this principle that concentrate and reduce the discharge of wastewater or concentrate and purify liquids to be treated. Vacuum evaporators are important chemical equipment. Vacuum evaporation is an evaporation operation performed under vacuum. Under low pressure, the boiling point of the solution decreases, and a large amount of water is evaporated with less vapor. It can be used to treat heat-sensitive materials that are easily decomposed at high temperatures and is commonly used for product separation and concentration. It is widely used in wastewater treatment, pharmaceutical equipment, and other industrial applications.

[0003] After heat pump evaporation and concentration, distilled water that meets discharge standards can be extracted from wastewater. This distilled water can be discharged directly, and the remaining concentrate can be discharged to a wastewater treatment plant for further treatment, which can greatly reduce the wastewater treatment costs for enterprises.

[0004] The applicant found some existing technologies for vacuum evaporation of liquid feed, such as patent publication number CN112661219A. The main technical means of this technology is to actively heat the waste liquid entering the evaporator by setting up a heating component, so that it forms vapor in the evaporator and exchanges heat with the heat exchange medium in the condenser, thereby replenishing the heat exchange medium for the compressor. After analysis, the applicant found that the drawback of this technical solution is that when the vacuum evaporator processes high-salt liquid feed, salt will precipitate during the heat exchange process. If the salt is not automatically separated in time, it will deposit at the bottom of the vacuum evaporator or even adhere to the surface of the heat exchanger, thus affecting the subsequent heat exchange between the refrigerant and the liquid feed. Based on this, the present invention provides a process for an efficient heat exchange vacuum evaporator for high-concentration brine that can automatically circulate and separate salt without stopping. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a process for a high-efficiency heat exchange vacuum evaporator for high-concentration brine, thereby solving the technical problem of the inability to automatically separate salts in a timely manner when processing high-salt liquids.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A process for a high-efficiency heat exchanger vacuum evaporator for high-concentration brine, the process comprising the following specific steps:

[0008] Step S1: Input high-concentration liquid into the feed relay tank and start the negative pressure component to make the pressure in the first evaporator and the second evaporator negative, so that the boiling point of the liquid in the first evaporator and the second evaporator decreases.

[0009] Step S2: The feed relay tank feeds high-concentration feed liquid into the first evaporator and the second evaporator through the feed pipe. The high-concentration feed liquid in the second evaporator enters the second evaporation heat exchanger, and the high-concentration feed liquid in the first evaporator circulates between the first evaporation heat exchanger and the first evaporator through the circulation pump.

[0010] Step S3: The hot refrigerant that has absorbed heat from the compressor is introduced into the first evaporator. The hot refrigerant enters the first evaporator heat exchanger and exchanges heat with the high-concentration liquid in the first evaporator heat exchanger to generate steam and the first concentrate. The hot refrigerant undergoes a phase change to become liquid refrigerant, and the liquid refrigerant is introduced into the refrigerant heat exchanger.

[0011] Step S4: Monitor the high-concentration liquid in the first evaporator using the monitoring component, and when the monitoring index value reaches the threshold, output the first concentrate to the centrifuge through the negative pressure pump for salt separation, producing mother liquor and non-flowing salt, wherein the water content of the non-flowing salt is 5%-10%;

[0012] Step S5: Transfer the mother liquor to the high-concentration water relay tank through the first control valve and collect the salt in a non-drip state;

[0013] Step S6: The mother liquor in the high-concentration water relay tank is fed into the first evaporator through the second control valve, mixed with the high-concentration liquid entering the first evaporator, and simultaneously circulated between the first evaporation heat exchanger and the first evaporator for evaporation;

[0014] Step S7: The steam generated in the first evaporator is fed into the impurity removal separator for impurity removal. The steam output from the impurity removal separator enters the second evaporator to exchange heat and evaporate with the high-concentration liquid in the second evaporation heat exchanger.

[0015] Step S8: The steam and steam condensate generated in the second evaporator are respectively fed into the refrigerant heat exchanger through two pipes;

[0016] Step S9: The second concentrated liquid after evaporation in the second evaporator is output to the high-concentration water relay tank through the sixth control valve and the negative pressure pump, and mixed with the mother liquor.

[0017] As a further aspect of the present invention: the monitoring component is a current monitor. When the current value monitored by the current monitor reaches the threshold, the solid content of the first concentrate in the first evaporator is 8%-15%. At this time, the first concentrate is output to the centrifuge through a negative pressure pump for salt separation, producing mother liquor and non-water-flowing salt.

[0018] As a further aspect of the present invention, step S3 specifically includes the following steps:

[0019] Step S31: The refrigerant output from the refrigerant heat exchanger is compressed by the compressor and becomes a hot refrigerant with high temperature and high pressure;

[0020] Step S32: The hot refrigerant is introduced into the first evaporator heat exchanger, where the hot refrigerant exchanges heat with the high-concentration liquid flowing from the first evaporator to the first evaporator heat exchanger, generating steam, and the hot refrigerant undergoes a phase change to become liquid refrigerant.

[0021] Step S33: The liquid refrigerant is introduced into the cooler for heat exchange, and then introduced into the refrigerant heat exchanger through the throttling device.

[0022] As a further aspect of the present invention, step S33 specifically includes the following steps:

[0023] Step S331: The refrigeration unit delivers heat exchange medium to the cooler;

[0024] Step S332: The liquid refrigerant after heat exchange in the first evaporator heat exchanger is input into the cooler. The heat exchange medium in the cooler absorbs the heat of the liquid refrigerant and flows back to the refrigeration unit.

[0025] Step S333: The heat exchange medium with heat in the refrigeration unit flows to the preheating heat exchanger, while the high-concentration liquid in the liquid relay tank circulates between the liquid relay tank and the preheating heat exchanger through the liquid circulation pump.

[0026] Step S334: The high-concentration liquid absorbs heat after passing through the preheating heat exchanger and flows back to the liquid relay tank.

[0027] As a further aspect of the present invention: the negative pressure component includes a distilled water tank and a vacuum component.

[0028] As a further aspect of the present invention: the distilled water tank is connected to the refrigeration unit, and part of the heat exchange medium flowing from the refrigeration unit to the cooler flows into the distilled water tank, absorbs the heat in the distilled water tank, and then flows back into the refrigeration unit.

[0029] As a further aspect of the present invention: a refrigeration solenoid valve is connected between the cooler and the throttling device.

[0030] As a further aspect of the present invention: a liquid level sensor is installed in both the first evaporator and the second evaporator, and a fifth control valve is installed on the liquid delivery pipe between the liquid relay tank and the first evaporator and the second evaporator respectively. When the liquid level sensor detects that the liquid level of the high-concentration liquid in the tank reaches the threshold, the corresponding control valve is closed, and the input of high-concentration liquid into the tank is stopped.

[0031] As a further aspect of the present invention: a defoamer pipe is connected to the second evaporator, and a seventh control valve is provided on the defoamer pipe; a cleaning water pipe is connected to the first evaporator, and an eighth control valve is provided on the cleaning water pipe.

[0032] The beneficial effects of this invention are:

[0033] (1) In this invention, the high-concentration liquid that circulates between the first evaporator and the first evaporator heat exchanger by the circulation pump, after flowing into the first evaporator heat exchanger, undergoes heat exchange and evaporation with the high-temperature hot refrigerant. When the monitoring index of the monitoring component reaches the preset threshold, the first evaporator is in the state of the first concentrated liquid. The first concentrated liquid is determined to be in the state of solid-liquid mixture. At this time, the first concentrated liquid is output to the centrifuge by the negative pressure pump for salt separation. With the high-speed circulation achieved by the circulation pump, the high-concentration liquid can be discharged from the evaporator when it is evaporated to the state of solid-liquid mixture. This avoids excessive salt precipitation in the evaporator, which would cause salt to deposit at the bottom of the evaporator and not be discharged smoothly, or adhere to the surface of the heat exchange tube in the heat exchanger, resulting in a decrease in the contact area between the high-concentration liquid and the refrigerant, thereby affecting the heat exchange and evaporation efficiency.

[0034] (2) In this invention, the evaporation conditions in the second evaporator are insufficient to cause the high-concentration liquid to precipitate salt. The second evaporator can evaporate part of the high-concentration liquid into a second concentrate, and then output the second concentrate to the high-concentration water relay tank to mix with the mother liquor after salt separation, and then input it into the first evaporator to mix with the high-concentration liquid entering the first evaporator. Simultaneously, it circulates between the first evaporation heat exchanger and the first evaporator to carry out reciprocating heat exchange evaporation, thereby improving the processing efficiency of the high-concentration liquid.

[0035] (3) In this invention, the refrigerant output from the first evaporator is in a gas-liquid mixed state and has heat. By utilizing the circulation line of the cooler and the refrigeration unit, this heat can be conducted, thereby preheating the high-concentration liquid in the feed liquid relay tank, greatly shortening the process time for the high-concentration liquid to reach the evaporation conditions, and reducing the loss of cooling capacity. It can also use the heat of the refrigerant after evaporation to promote the condensation of the vapor after evaporation, and simultaneously preheat the high-concentration liquid before evaporation, combining the advantages of rapid preheating, low energy consumption, and low requirements for heat dissipation and exhaust volume. Attached Figure Description

[0036] The invention will now be further described with reference to the accompanying drawings.

[0037] Figure 1 This is a schematic diagram of the process flow of the present invention.

[0038] In the diagram: 1. First evaporator; 2. Second evaporator; 3. Refrigerant heat exchanger; 4. Distilled water tank; 5. Impurity separator; 6. Feed transfer tank; 7. First evaporator heat exchanger; 8. Second evaporator heat exchanger; 9. High-concentration water transfer tank; 10. Circulation pump; 11. First control valve; 12. Centrifuge; 13. Second control valve; 14. Third control valve; 15. Negative pressure pump; 16. Fourth control valve; 17. Cooler; 18. Compressor; 19. Refrigeration unit; 20. Preheating heat exchanger; 21. Feed circulation pump; 22. Vacuum assembly; 23. Throttling device; 24. Refrigeration solenoid valve; 25. Fifth control valve; 26. Sixth control valve; 27. Seventh control valve; 28. Eighth control valve. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Please see Figure 1 As shown, this invention relates to a process for a high-efficiency heat exchanger vacuum evaporator for high-concentration brine, the process comprising the following specific steps:

[0041] Step S1: Input high-concentration liquid into the liquid relay tank 6, start the negative pressure component, so that the pressure in the first evaporator 1 and the second evaporator 2 is negative, and the boiling point of the liquid in the first evaporator 1 and the second evaporator 2 decreases.

[0042] Step S2: The feed relay tank 6 feeds high-concentration feed liquid into the first evaporator 1 and the second evaporator 2 through the feed pipe. The high-concentration feed liquid in the second evaporator 2 enters the second evaporation heat exchanger 8, and the high-concentration feed liquid in the first evaporator 1 circulates between the first evaporation heat exchanger 7 and the first evaporator 1 through the circulation pump 10.

[0043] Step S3: The hot refrigerant after absorbing heat from the compressor 18 is input into the first evaporator 1. The hot refrigerant enters the first evaporator heat exchanger 7 and exchanges heat with the high-concentration liquid in the first evaporator heat exchanger 7 to generate steam and the first concentrate. The hot refrigerant undergoes a phase change to become liquid refrigerant. The liquid refrigerant is input into the refrigerant heat exchanger 3.

[0044] Step S4: Monitor the high-concentration liquid in the first evaporator 1 using the monitoring component, and when the monitoring index value reaches the threshold, output the first concentrate to the centrifuge 12 through the negative pressure pump 15 for salt separation, producing mother liquor and non-flowing salt, wherein the water content of the non-flowing salt is 5%-10%;

[0045] Step S5: Transfer the mother liquor to the high-concentration water relay tank 9 through the first control valve 11, and collect the salt in a non-drip state;

[0046] Step S6: The mother liquor in the high-concentration water relay tank 9 is fed into the first evaporator 1 through the second control valve 13, where it is mixed with the high-concentration liquid entering the first evaporator 1 and simultaneously circulated between the first evaporation heat exchanger 7 and the first evaporator 1 for evaporation.

[0047] Step S7: The steam generated in the first evaporator 1 is fed into the impurity removal separator 5 for impurity removal. The steam output from the impurity removal separator 5 enters the second evaporator 2 to exchange heat and evaporate with the high-concentration liquid in the second evaporation heat exchanger 8.

[0048] Step S8: The steam and steam condensate generated in the second evaporator 2 are respectively fed into the refrigerant heat exchanger 3 through two pipes;

[0049] Step S9: The second concentrated liquid after evaporation in the second evaporator 2 is output to the high-concentration water relay tank 9 through the sixth control valve 26 and the negative pressure pump 15, and mixed with the mother liquor.

[0050] The high-concentration brine high-efficiency heat exchange vacuum evaporator includes:

[0051] The first evaporator 1 is connected to the second evaporator 2 through the impurity separator 5, and the first evaporator 1 and the second evaporator 2 are respectively connected to the feed liquid relay tank 6. The second evaporator 2 is equipped with a second evaporation heat exchanger 8. The first evaporator 1 and the second evaporator 2 are both connected to the negative pressure component.

[0052] A first evaporator heat exchanger 7 is connected to a first evaporator tank 1, and a circulating pump 10 is installed on the connecting pipe between the two. The first evaporator heat exchanger 7 is also connected to a refrigerant heat exchanger 3.

[0053] Centrifuge 12 is connected to the second evaporator 2, and a negative pressure pump 15 is installed on the connecting pipe between the two. The liquid outlet of centrifuge 12 is connected to the high concentration water relay tank 9, and the liquid outlet of the high concentration water relay tank 9 is connected to the second evaporator 2.

[0054] The liquid refrigerant output from the refrigerant heat exchanger 3 is transformed into hot refrigerant by the compressor 18, and then the hot refrigerant is input into the first evaporator heat exchanger 7.

[0055] The output end of the first evaporator heat exchanger 7 is connected to the input end of the refrigerant heat exchanger 3, and a cooler 17 is provided on the connecting pipeline between the two. The cooler 17 is connected to the refrigeration unit 19, and the refrigeration unit 19 is connected to the preheating heat exchanger 20. The high-concentration liquid in the feed relay tank 6 circulates between the feed relay tank 6 and the preheating heat exchanger 20 through the feed circulation pump 21. The first evaporator heat exchanger 7 can be a shell and tube heat exchanger, or other heat exchangers, without specific limitations.

[0056] The refrigerant is discharged as a high-temperature hot refrigerant after the compressor 18 performs work, which serves as the heat source for the first evaporator 1. The hot refrigerant is liquefied by releasing heat in the first evaporation heat exchanger 7. The non-water-flowing salt is a salt that does not precipitate out of the solution in crystal form.

[0057] In one embodiment, the impurity separator 5 can be a cyclone separator. After the steam generated in the first evaporator 1 enters it, the entrained water droplets are thrown back into the first evaporator 1 for further evaporation. Of course, the impurity separator 5 can also be other structural components capable of impurity removal; this embodiment does not impose specific limitations on it. The first evaporator 1 and the second evaporator 2 can be adopted as follows: Figure 1 The top-to-bottom installation method shown can also be used with parallel installation methods; no specific restrictions are imposed here.

[0058] It should be noted that a third control valve 14 is provided at the discharge end of the first evaporator 1, and a fourth control valve 16 is connected between the negative pressure pump 15 and the centrifuge 12; the aforementioned control valves, compressor 18 and negative pressure components and other electrical components are all connected to an external controller. The external controller is existing technology and this application has not improved it. Therefore, it is not necessary to disclose its specific mechanical structure and circuit structure, and it does not affect the integrity of this application.

[0059] Furthermore, when processing high-concentration liquids, salt precipitation will inevitably occur when evaporation reaches a certain stage. The high-concentration liquid in the first evaporator 1 of this application circulates continuously, which is sufficient to cause salt precipitation in the high-concentration liquid. Salt precipitation is also a necessary step in the high-concentration liquid processing process. In the second evaporator 2, evaporation and heat exchange are carried out through the steam generated in the first evaporator 1 and the second evaporation heat exchanger 8. By controlling the opening and closing time of the sixth control valve 26, the heat exchange efficiency of the second evaporation heat exchanger 8, and the action time of the negative pressure pump 15, the second concentrate in the second evaporator 2 is controlled to be insufficient to meet the salt precipitation conditions.

[0060] In practical application, the high-temperature hot refrigerant after the compressor 18 has performed its work enters the first evaporator heat exchanger 7 and exchanges heat with the highly concentrated liquid flowing from the first evaporator tank 1 into the first evaporator heat exchanger 7. The liquid refrigerant after phase change is input into the refrigerant heat exchanger 3, and after performing work, it circulates back to the first evaporator heat exchanger 7 for heat exchange and evaporation. The highly concentrated liquid, which circulates between the first evaporator tank 1 and the first evaporator heat exchanger 7 via the circulation pump 10, exchanges heat with the high-temperature hot refrigerant and evaporates after flowing into the first evaporator heat exchanger 7. When the monitoring component reaches the preset threshold, the first evaporator tank 1 contains the first concentrate, which is determined to be a solid-liquid mixture. At this time, the first concentrate is output to the centrifuge 12 for salt separation by the negative pressure pump 15. With the high-speed circulation achieved by the circulation pump 10, the highly concentrated liquid can be discharged when it evaporates to a solid-liquid mixture state. The evaporator is designed to prevent excessive salt precipitation, which can lead to salt deposits at the bottom of the evaporator that cannot be discharged smoothly, or salt adhering to the surface of the heat exchange tubes in the heat exchanger. This reduces the contact area between the high-concentration liquid and the refrigerant, thus affecting the heat exchange and evaporation efficiency. The second evaporator 2 can evaporate part of the high-concentration liquid into a second concentrate. The evaporation conditions in the second evaporator 2 are insufficient to cause salt precipitation in the high-concentration liquid. In other words, the second concentrate is an incompletely processed liquid. Subsequently, the second concentrate is output to the high-concentration water relay tank 9 through the sixth control valve 26 and the negative pressure pump 15, where it can be mixed with the mother liquor after salt separation. Then, the two are fed into the first evaporator 1 through the second control valve 13 and mixed with the high-concentration liquid entering the first evaporator 1. They circulate synchronously between the first evaporation heat exchanger 7 and the first evaporator 1, performing reciprocating cyclic heat exchange and evaporation, thereby improving the processing efficiency of the high-concentration liquid.

[0061] like Figure 1 As shown, in a preferred embodiment of the present invention, the monitoring component is a current monitor. When the current value monitored by the current monitor reaches the threshold, the solid content of the first concentrate in the first evaporator 1 is 8%-15%. At this time, the first concentrate is output to the centrifuge 12 through the negative pressure pump 15 for salt separation, producing mother liquor and non-water-flowing salt.

[0062] In one embodiment, the monitoring component can also be configured as a liquid level sensor. When the liquid level of the high-concentration liquid input into the first evaporator 1 reaches the first threshold, the input is stopped. Then, the liquid is circulated to evaporate the high-concentration liquid. When the liquid level drops to the second threshold, the water content drops to the critical value for salt precipitation, that is, the first concentrate reaches the discharge standard. Then, the first concentrate is output to the centrifuge 12 for salt separation by the negative pressure pump 15.

[0063] In practical application, the monitoring component is used to monitor the current value of the high-concentration liquid in the first evaporator 1. When the monitored current value reaches the threshold, it reflects that the evaporation process has reached a certain level, and it can be determined that some salt has been precipitated in the first evaporator 1. The solid content of the first concentrate is 8%-15%, which meets the discharge standard. Then, the first concentrate is output to the centrifuge 12 for salt separation by the negative pressure pump 15. However, the small amount of salt precipitated at this time will not be deposited in the first evaporator 1, but will be discharged into the centrifuge 12 along with the first concentrate.

[0064] like Figure 1 As shown, in a preferred embodiment of the present invention, step S3 specifically includes the following steps:

[0065] Step S31: The refrigerant output from the refrigerant heat exchanger 3 is compressed by the compressor 18 and becomes a hot refrigerant with high temperature and high pressure.

[0066] Step S32: The hot refrigerant is introduced into the first evaporator heat exchanger 7, whereby the hot refrigerant exchanges heat with the high-concentration liquid flowing from the first evaporator tank 1 into the first evaporator heat exchanger 7, generating steam, and the hot refrigerant undergoes a phase change to become liquid refrigerant.

[0067] Step S33: The liquid refrigerant is introduced into the cooler 17 for heat exchange, and then introduced into the refrigerant heat exchanger 3 through the throttling device 23.

[0068] In one embodiment, step S33 specifically includes the following steps:

[0069] Step S331: The refrigeration unit 19 supplies heat exchange medium to the cooler 17;

[0070] Step S332: The liquid refrigerant after heat exchange in the first evaporator heat exchanger 7 is input into the cooler 17. The heat exchange medium in the cooler 17 absorbs the heat of the liquid refrigerant and flows back to the refrigeration unit 19.

[0071] Step S333: The heat exchange medium containing heat in the refrigeration unit 19 flows to the preheating heat exchanger 20, while the high-concentration liquid in the liquid relay tank 6 circulates between the liquid relay tank 6 and the preheating heat exchanger 20 through the liquid circulation pump 21.

[0072] Step S334: The high-concentration liquid absorbs heat through the preheating heat exchanger 20 and flows back to the liquid relay tank 6.

[0073] Considering that the temperature inside the first evaporator 1 rises after evaporation for a period of time, which would prevent the hot refrigerant from undergoing a complete phase change, the refrigerant output from the first evaporator 1 is in a gas-liquid mixed state and has heat. This heat can be conducted through the circulation line between the cooler 17 and the refrigeration unit 19, thereby achieving the preheating of the feed liquid relay tank 6.

[0074] The refrigeration unit 19 can be a water chiller, with water as the transmission medium. It can also be an air-cooled or refrigerant system, with the medium being adaptably adjusted as long as the heat exchange effect can be achieved. No specific limitations are made here.

[0075] In practical application, the liquid refrigerant after heat exchange in the first evaporator heat exchanger 7 is input into the cooler 17, and then into the refrigerant heat exchanger 3 through the throttling device 23. The throttling device 23 can be an expansion valve, which is equivalent to a small orifice that allows the liquid refrigerant to be sprayed into a mist. Accompanied by the energy change of the refrigerant heat exchanger 3, the refrigerant vaporizes and absorbs heat, and condenses the water vapor output from the second evaporator 2 into water. Of course, the throttling device 23 can also be other structures that can achieve the throttling effect, such as capillary tubes, etc., which are not specifically limited here. The refrigeration unit 19 adopts a non-standard structure refrigeration unit. The principle of unit 19 is the same as that of compressor 18. The refrigerant at the heat pump outlet of refrigeration unit 19 passes through cooler 17. A pump in cooler 17 exchanges heat between the liquid and the refrigerant to preheat the liquid relay tank 6. This can preheat the high-concentration liquid entering the first evaporator 1 and the second evaporator 2, greatly shortening the time required for the high-concentration liquid to reach the evaporation conditions, while reducing the loss of cooling capacity. It can also use the heat from the refrigerant after evaporation to promote the condensation of the vapor after evaporation, and simultaneously preheat the high-concentration liquid before evaporation. It combines the advantages of rapid preheating, low energy consumption, and low requirements for heat dissipation and exhaust volume.

[0076] like Figure 1 As shown, in a preferred embodiment of the present invention, the negative pressure assembly includes a distilled water tank 4 and a vacuum assembly 22.

[0077] It should be noted that the vacuum component 22 can be a vacuum centrifugal pump or a water ring vacuum component, as long as it can achieve a negative pressure environment. This embodiment does not impose any specific limitations.

[0078] In practical application, the vacuum component 22 makes the pressure inside the first evaporator 1 negative, thus lowering the boiling point of the water inside the first evaporator 1.

[0079] like Figure 1 As shown, in a preferred embodiment of the present invention, the distilled water tank 4 is connected to the refrigeration unit 19. The heat exchange medium flowing from the refrigeration unit 19 to the cooler 17 flows into the distilled water tank 4, absorbs the heat in the distilled water tank 4, and then flows back into the refrigeration unit 19.

[0080] In practical application, the heat in the distilled water tank 4 can be conducted by the heat exchange medium input to it, and the heat exchange medium after heat exchange flows back to the refrigeration unit 19, which can ensure the low temperature environment in the distilled water tank 4, and at the same time make full use of the waste heat, realize the full utilization of heat, and reduce heat loss.

[0081] like Figure 1 As shown, in a preferred embodiment of the present invention, a refrigeration solenoid valve 24 is connected between the cooler 17 and the throttling device 23.

[0082] like Figure 1 As shown, in a preferred embodiment of the present invention, a liquid level sensor is provided in both the first evaporator 1 and the second evaporator 2. A fifth control valve 25 is provided on the liquid delivery pipe between the liquid relay tank 6 and the first evaporator 1 and the second evaporator 2. When the liquid level sensor detects that the liquid level of the high-concentration liquid in the tank reaches the threshold, the corresponding control valve is closed, and the input of high-concentration liquid into the tank is stopped.

[0083] like Figure 1 As shown, in a preferred embodiment of the present invention, the second evaporator 2 is connected to a defoamer pipe and a seventh control valve 27 is provided on the defoamer pipe, and the first evaporator 1 is connected to a cleaning water pipe and an eighth control valve 28 is provided on the cleaning water pipe.

[0084] In practical application, this embodiment allows defoamer to be introduced into the second evaporator 2 via the defoamer pipe and the seventh control valve 27. The second evaporator 2 and the first evaporator 1 are connected. In addition, the cleaning water pipe and the eighth control valve 28 are used to introduce cleaning water, which can clean the two evaporators and avoid the problem of reduced wastewater evaporation efficiency caused by a lot of dirt adhering to the tank wall after long-term use.

[0085] Working principle of the invention: The above embodiments of the invention provide a process for a high-efficiency heat exchange vacuum evaporator for high-concentration brine. The high-concentration liquid, which circulates between the first evaporator tank 1 and the first evaporator heat exchanger 7 via a circulation pump 10, exchanges heat with the high-temperature hot refrigerant in the first evaporator heat exchanger 7. When the monitoring index of the monitoring component reaches a preset threshold, the first evaporator tank 1 contains the first concentrated liquid, which is determined to be a solid-liquid mixture. At this time, the first concentrated liquid is output to the centrifuge 12 for salt separation by a negative pressure pump 15. The high-speed circulation achieved by the circulation pump 10 enables the high-concentration liquid to be discharged from the evaporator tank when it evaporates to a solid-liquid mixture state. This avoids excessive salt precipitation in the evaporator tank, which would cause salt to deposit at the bottom of the evaporator tank and not be discharged smoothly, or adhere to the surface of the heat exchange tubes in the heat exchanger, resulting in a decrease in the contact area between the high-concentration liquid and the refrigerant, thereby affecting the heat exchange evaporation efficiency.

[0086] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A process for a high-efficiency heat exchanger vacuum evaporator for high-concentration brine, characterized in that, The process includes the following specific steps: Step S1: Input high-concentration liquid into the liquid relay tank (6), start the negative pressure component, so that the pressure in the first evaporator (1) and the second evaporator (2) is negative, and the boiling point of the liquid in the first evaporator (1) and the second evaporator (2) decreases; Step S2: The feed relay tank (6) feeds high-concentration feed liquid into the first evaporator (1) and the second evaporator (2) through the feed pipe. The high-concentration feed liquid in the second evaporator (2) enters the second evaporation heat exchanger (8), and the high-concentration feed liquid in the first evaporator (1) circulates between the first evaporation heat exchanger (7) and the first evaporator (1) through the circulation pump (10). Step S3: The hot refrigerant after absorbing the heat of the compressor (18) is input into the first evaporator (1). The hot refrigerant enters the first evaporator heat exchanger (7) and exchanges heat with the high-concentration liquid in the first evaporator heat exchanger (7) to generate steam and the first concentrate. The hot refrigerant undergoes a phase change to become liquid refrigerant. The liquid refrigerant is input into the refrigerant heat exchanger (3). Step S4: Monitor the high-concentration liquid in the first evaporator (1) through the monitoring component, and when the monitoring index value reaches the threshold, output the first concentrate to the centrifuge (12) through the negative pressure pump (15) for salt separation to produce mother liquor and non-flowing salt. The water content of the non-flowing salt is 5%-10%. Step S5: Transfer the mother liquor to the high-concentration water relay tank (9) through the first control valve (11) and collect the salt in a non-flowing state; Step S6: The mother liquor in the high-concentration water relay tank (9) is fed into the first evaporator (1) through the second control valve (13) and mixed with the high-concentration liquid entering the first evaporator (1). The mixture is simultaneously circulated between the first evaporation heat exchanger (7) and the first evaporator (1) for evaporation. Step S7: The steam generated in the first evaporator (1) is fed into the impurity removal separator (5) for impurity removal. The steam output from the impurity removal separator (5) enters the second evaporator (2) to exchange heat with the high-concentration liquid in the second evaporation heat exchanger (8) for evaporation. Step S8: The steam generated in the second evaporator (2) and the steam condensate are respectively fed into the refrigerant heat exchanger (3) through two pipes; Step S9: The second concentrated liquid after evaporation in the second evaporator (2) is output to the high-concentration water relay tank (9) through the sixth control valve (26) and the negative pressure pump (15) and mixed with the mother liquor; by controlling the opening and closing time of the sixth control valve (26), the heat exchange efficiency of the second evaporator heat exchanger (8) and the action time of the negative pressure pump (15), the second concentrated liquid in the second evaporator (2) is controlled to be insufficient to meet the salt precipitation conditions; The monitoring component is a current monitor. When the current value monitored by the current monitor reaches the threshold, the solid content of the first concentrated liquid in the first evaporator (1) is 8%-15%. At this time, the first concentrated liquid is output to the centrifuge (12) through the negative pressure pump (15) for salt separation, producing mother liquor and non-water-flowing salt. Step S3 specifically includes the following steps: Step S31: The refrigerant output through the refrigerant heat exchanger (3) is compressed by the compressor (18) and becomes a hot refrigerant with high temperature and high pressure. Step S32: The hot refrigerant is introduced into the first evaporator heat exchanger (7), and the hot refrigerant exchanges heat with the high-concentration liquid flowing from the first evaporator (1) into the first evaporator heat exchanger (7) to generate steam, and the hot refrigerant undergoes a phase change to become liquid refrigerant. Step S33: The liquid refrigerant is introduced into the cooler (17) for heat exchange, and then introduced into the refrigerant heat exchanger (3) through the throttling device (23); Step S33 specifically includes the following steps: Step S331: The refrigeration unit (19) delivers heat exchange medium to the cooler (17); Step S332: The liquid refrigerant after heat exchange in the first evaporator heat exchanger (7) is input into the cooler (17). The heat exchange medium in the cooler (17) absorbs the heat of the liquid refrigerant and flows back to the refrigeration unit (19). Step S333: The heat exchange medium with heat in the refrigeration unit (19) flows to the preheating heat exchanger (20), while the high-concentration liquid in the liquid relay tank (6) circulates between the liquid relay tank (6) and the preheating heat exchanger (20) through the liquid circulation pump (21); Step S334: The high-concentration liquid absorbs heat after passing through the preheating heat exchanger (20) and flows back to the liquid relay tank (6); Liquid level sensors are installed in both the first evaporator (1) and the second evaporator (2). A fifth control valve (25) is installed on the liquid delivery pipe between the liquid relay tank (6) and the first evaporator (1) and the second evaporator (2). When the liquid level sensor detects that the liquid level of the high-concentration liquid in the tank reaches the threshold, the corresponding control valve is closed, and the input of high-concentration liquid into the tank is stopped.

2. The process for a high-efficiency heat exchanger vacuum evaporator for high-concentration brine according to claim 1, characterized in that, The negative pressure assembly includes a distilled water tank (4) and a vacuum assembly (22).

3. The process for a high-efficiency heat exchanger vacuum evaporator for high-concentration brine according to claim 2, characterized in that, The distilled water tank (4) is connected to the refrigeration unit (19). The heat exchange medium flowing from the refrigeration unit (19) to the cooler (17) flows into the distilled water tank (4) and absorbs the heat in the distilled water tank (4) before flowing back into the refrigeration unit (19).

4. The process for a high-efficiency heat exchanger vacuum evaporator for high-concentration brine according to claim 1, characterized in that, A refrigeration solenoid valve (24) is connected between the cooler (17) and the throttling device (23).

5. The process for a high-efficiency heat exchanger vacuum evaporator for high-concentration brine according to claim 1, characterized in that, The second evaporator (2) is connected to a defoamer pipe and a seventh control valve (27) is provided on the defoamer pipe. The first evaporator (1) is connected to a cleaning water pipe and an eighth control valve (28) is provided on the cleaning water pipe.

Images