Mvr evaporation process and system

Abstract

The application discloses an MVR evaporation process method and system, relates to the technical field of MVR evaporation processes, and comprises the following steps: a feed pump pumps raw materials to a preheater; the raw materials are heated in the preheater and then flow into a separator; the raw materials are evaporated and separated in the separator to form steam and solid-containing liquid; the steam is compressed and heated by a steam compressor; the heated steam flows into a heater; the solid-containing liquid flows into a settling tank for settling and separation to form upper and lower layers of clear liquid and solid-containing liquid, and the solid-containing liquid returns to the separator; a circulating pump is controlled to pump the clear liquid to the heater to exchange heat with the heated steam; condensed water formed by the exchanged steam is transported to the preheater for preheating; the exchanged and heated clear liquid flows into the separator; the exchanged and heated clear liquid is mixed with the raw materials and the returned solid-containing liquid in the separator to form solid-containing concentrated liquid and flash out steam, and the steam is repeatedly compressed and heated; part of the solid-containing concentrated liquid flows into the settling tank to repeat the above steps, and the other part of the solid-containing concentrated liquid flows out of the separator.

Description

Technical Field

[0001] This invention relates to the field of evaporation technology, and in particular to an MVR evaporation process method and system. Background Technology

[0002] MVR, short for Mechanical Vapor Recompression, is widely used in chemical separation and zero-discharge industrial wastewater treatment. A complete MVR evaporation system typically consists of a feed pump, heater, evaporator, steam compressor, and circulation pump. The material is heated by compressed steam outside the heat exchange tubes of the heater and then enters the evaporator under the action of the circulation pump, where water evaporates. The material, heated by the heater, is concentrated in the evaporator to form a solid-containing concentrate or supersaturated solution, thus forming crystals or promoting crystal growth. The material temperature decreases, and the supersaturated state is de-saturated. The de-saturated material enters the circulation pump and, under the action of the circulation pump, enters the heater again for reheating. This cycle continues, evaporating and concentrating or crystallizing. The solid-containing concentrate or crystal slurry in the evaporator is discharged from the bottom.

[0003] In existing MVR processes, the solid-containing liquid formed after material evaporation and separation in the evaporator is directly fed into the heater by a circulating pump for heating, and then returned to the evaporator for further evaporation, thus circulating and concentrating the liquid. However, the complex fluid atmosphere created by the flash evaporation of hot material in the evaporator results in a large amount of solid particles and supersaturated salts in the material entering the heater from the separator. These particles easily precipitate and form scale in the system pipes and heater as the material flows through, leading to corrosion, shortening equipment lifespan, reducing heat exchange efficiency, causing poor system stability, and requiring frequent shutdowns for cleaning, resulting in low operational efficiency. Furthermore, the vacuum operating conditions of existing MVR systems cause condensate from the heater to flash into the vacuum system, leading to heat loss and reduced vacuum system efficiency.

[0004] Therefore, it is necessary to provide a new MVR evaporation process method and system to solve the aforementioned technical problems. Summary of the Invention

[0005] The main objective of this invention is to propose an MVR evaporation process method and system, aiming to improve the technical problem of low efficiency in existing MVR evaporation operations.

[0006] To achieve the aforementioned objective, according to one aspect of the present invention, an MVR evaporation process method is provided, the MVR evaporation process method comprising the following steps: S1. Control the feed pump to pump the raw material to the preheater, and the raw material enters the separator after heat exchange and temperature rise in the preheater. S2. The raw material is flash-separated in the separator to form steam and solid-containing liquid; the steam enters the steam compressor for compression and heating, and the heated steam flows into the heater; the solid-containing liquid flows from the upper part of the separator into the settling tank for settling and separation to form clear liquid and solid-containing liquid in upper and lower layers, and the solid-containing liquid is returned to the separator. S3. Control the circulating pump to pump the clear liquid to the heater, where it exchanges heat with the heated steam; the condensate formed by the heated steam is transported to the condensate tank; the heated clear liquid flows into the separator. S4. After heat exchange and heating, the clear liquid is mixed with the raw material and the reflux solid-containing liquid in the separator, and then the steam is separated by flash evaporation to obtain a solid-containing concentrate. The steam enters the steam compressor to repeat steps S2 and S3. A portion of the solid-containing concentrate flows into the settling tank, and the settling separation in step S2 and step S3 are repeated. The other portion flows out of the separator.

[0007] In one embodiment, the step of conveying the condensate formed from the heat-exchanged steam to a condensate tank includes: S31. Control the condensate pump to pump the condensate to the condensate tank, and the condensate flashes in the condensate tank to generate secondary steam. S32. The secondary steam, together with the steam flashed out of the separator, is compressed and heated by the steam compressor and then flows into the heater. S33. The condensate after flash evaporation is pumped to the preheater to preheat the raw materials.

[0008] In one embodiment, a gas scrubbing device is connected between the separator and the steam compressor, and the step of the steam entering the steam compressor for compression and heating includes: S21. The steam enters the steam compressor after the air washing device removes the liquid droplets it carries.

[0009] In one embodiment, the step of the other portion flowing out of the separator includes: S41. The solid-containing concentrate enters a thickener for thickening, and the thickened slurry enters a centrifuge for solid-liquid separation to obtain crystalline solid and centrifugal mother liquor. S42. The centrifugal mother liquor is discharged outside the system and / or returned to the separator via the mother liquor pump.

[0010] In one embodiment, the step of the clarified liquid flowing into the separator after heat exchange and heating includes: The clarified liquid, after being heated by heat exchange, enters the separator for flash evaporation.

[0011] According to another aspect of the present invention, the present invention also provides an MVR evaporation system, wherein the MVR evaporation system applies the MVR evaporation process method described above, and the MVR evaporation system comprises: A preheater, comprising an inlet and an outlet, wherein the inlet is used to supply raw materials; A separator, comprising a first inlet, a second inlet, a third inlet, a first outlet, and a second outlet, wherein the second outlet is used to discharge a concentrated liquid containing solids; A settling tank, comprising a settling inlet, an upper outlet, and a lower outlet, wherein the first outlet is connected to the settling inlet, and the lower outlet is connected to the second inlet; A heater, comprising a heating inlet and a heating outlet, wherein the heating inlet and the upper outlet are connected by a circulation pump, the heating outlet is connected to the third inlet, and the discharge outlet is connected to the first inlet, or the discharge outlet is connected to the connecting pipeline of the heating outlet and the third inlet; The steam compressor, the separator further includes a gas outlet, the heater further includes a gas inlet, and the gas outlet and the gas inlet are connected through the steam compressor; The heater further includes a condensate tank and a first condensate outlet connected to the condensate tank. The preheater also includes a condensate inlet and a second condensate outlet connected to the condensate tank, and the second condensate outlet is used to discharge condensate.

[0012] In one embodiment, the MVR evaporation system further includes a thickener and a centrifuge, with a second outlet of the separator connected to the thickener and the thickener connected to the centrifuge.

[0013] In one embodiment, the heater is a plate heat exchanger.

[0014] In one embodiment, the inlet of the steam compressor is connected to the condensate tank, and a regulating valve is provided between the steam compressor and the condensate tank.

[0015] In one embodiment, a throttling valve is provided between the heating outlet and the third inlet.

[0016] In the technical solution of this invention, the feed pump first pumps the raw material to the preheater. In the preheater, the raw material exchanges heat with high-temperature condensate from the heater and is heated before flowing into the separator from the preheater outlet. After entering the separator, the raw material undergoes evaporation separation to form steam and a solid-containing liquid. The steam enters the steam compressor from the separator's steam outlet, where it is compressed and heated to form high-temperature steam, which flows into the heater as a heat source. The solid-containing liquid flows from the separator's liquid outlet into a settling tank, where gravity settling separates the solids into upper and lower layers of clear liquid and solid-containing liquid. The lower layer of solid-containing liquid is returned to the separator.

[0017] A circulating pump directs the clarified liquid from the upper layer of the settling tank to a heater. Inside the heater, the clarified liquid undergoes indirect heat exchange with high-temperature steam from a steam compressor, causing its temperature to rise as it absorbs heat. The high-temperature steam releases heat in the heater and condenses to form high-temperature condensate. This condensate is then transported to a condensate tank and subsequently to a preheater for preheating the raw materials. The heated clarified liquid then flows out of the heater and into the separator.

[0018] After heat exchange and heating, the clarified liquid enters the separator, where it mixes with fresh raw material from the preheater and solid-containing liquid returned from the settling tank. Steam is then generated through flash evaporation, forming a solid-containing concentrate. The resulting steam is repeatedly compressed and heated in the steam compressor. The heated steam mixes again and flows into the heater to exchange heat with the clarified liquid. A portion of the solid-containing concentrate flows into the settling tank for further settling and separation, repeating the settling, separation, and clarified liquid heat exchange and return cycle. The remaining portion of the solid-containing concentrate flows out from the bottom of the separator and enters subsequent processing steps.

[0019] This invention separates solid-containing liquids by setting up a settling tank, allowing the clear liquid to enter the heater for heat exchange while the solid-containing liquid is directly returned to the separator. This eliminates impurities and crystals in the circulating liquid, preventing solid particles and supersaturated salts from entering the heater, thus effectively preventing scaling and corrosion inside the heater, ensuring heat exchange efficiency, and improving the stability and continuity of system operation. Furthermore, by installing a flash steam branch pipe between the condensate tank and the steam compressor, the secondary steam flashed from the condensate tank is recovered, effectively achieving waste heat recovery and utilization of the system. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 A flowchart of the first embodiment of the MVR evaporation process method provided by the present invention; Figure 2 A flowchart of a second embodiment of the MVR evaporation process method provided by the present invention; Figure 3 A flowchart of the third embodiment of the MVR evaporation process method provided by the present invention; Figure 4 This is a schematic flowchart of an embodiment of the MVR evaporation system provided by the present invention; Figure 5 This is a schematic flowchart of another embodiment of the MVR evaporation process method provided by the present invention.

[0022] Explanation of icon numbers: 100. MVR Evaporation System; 1. Preheater; 11. Feed Inlet; 12. Discharge Outlet; 13. Condensate Inlet; 14. Second Condensate Outlet; 2. Separator; 21. First Inlet; 22. Second Inlet; 23. Third Inlet; 24. First Outlet; 25. Second Outlet; 26. Gas Outlet; 3. Settling Tank; 31. Settling Inlet; 32. Upper Outlet; 33. Lower Outlet; 4. Heater; 41. Heating Inlet; 42. Heating Outlet; 43. Gas Inlet; 44. First Condensate Outlet; 5. Circulating Pump; 6. Steam Compressor; 7. Condensate Tank; 8. Regulating Valve; 9. Throttling Valve.

[0023] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0024] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0026] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0027] With the widespread application of MVR evaporation technology in chemical separation and zero-discharge of industrial wastewater, the problem of high concentration of solid materials and easy scaling in the feed liquid caused by the evaporation and concentration of the solution in the treated material has become increasingly prominent, which puts forward higher requirements for the anti-scaling performance of the heater and the stability of system operation.

[0028] In conventional MVR evaporation processes, the solid-containing liquid is directly fed into the heater by a circulating pump for heating, then returned to the evaporator for further evaporation, thus circulating and concentrating the liquid. However, the complex fluid atmosphere created by the flash evaporation of hot materials in the evaporator results in a large amount of solid particles and supersaturated salts entering the heater from the separator. These particles easily precipitate and form scale in the system pipes and heater as the material flows through, leading to corrosion, shortening equipment lifespan, reducing heat exchange efficiency, causing poor system stability, and requiring frequent shutdowns for cleaning, resulting in low operational efficiency. Furthermore, under vacuum operating conditions, condensate from the heater flashes in, causing heat loss and efficiency reduction. Therefore, the applicant has researched an MVR evaporation process where the solid-containing liquid undergoes sedimentation separation before entering the heater.

[0029] To achieve this objective, according to one aspect of the invention, please refer to... Figure 1 , Figure 1 This is a flowchart of a first embodiment of the MVR evaporation process method provided by the present invention. The present invention proposes an MVR evaporation process method, which includes the following steps: S1. Control the feed pump to pump the raw material to the preheater 1. After the raw material is heated by heat exchange in the preheater 1, it enters the separator 2. One end of the feed pump draws raw material from the raw material storage area and pumps it to the preheater 1. The raw material exchanges heat with the heat medium in the preheater 1, which raises the temperature of the raw material. This reduces the extra heat required for the raw material to reach the evaporation temperature after entering the separator 2, thereby reducing the load on the steam compressor 6.

[0030] S2. The raw material is evaporated and separated in the separator 2 to form steam and solid-containing liquid. The steam enters the steam compressor 6 for compression and heating. The heated steam flows into the heater 4. The solid-containing liquid flows from the upper part of the separator 2 into the settling tank 3 for settling and separation, forming clear liquid and solid-containing liquid in upper and lower layers. The solid-containing liquid is returned to the separator 2. After the raw material enters separator 2, it undergoes evaporation and separation within separator 2, forming steam and a solid-containing liquid. The steam enters steam compressor 6 from the steam outlet of separator 2, and after compression and heating, it forms high-temperature steam. This high-temperature steam flows into heater 4 as a heat source, realizing the energy recovery of secondary steam and effectively reducing the system's dependence on external energy. The solid-containing liquid flows from the liquid outlet of separator 2 into settling tank 3, where gravity settling separation is performed using the density difference between solid particles and liquid, forming upper and lower layers of clear liquid and solid-containing liquid. The lower layer of solid-containing liquid flows back to separator 2. Since the solid-containing liquid has been separated in settling tank 3 before entering heater 4 and is directly returned to separator 2, it avoids solid particles entering the downstream heater 4, reducing the risk of scaling in heater 4 from the source. At the same time, the solid-containing liquid returning to separator 2 can act as seed crystals to promote crystal growth and improve the evaporation-crystallization separation efficiency.

[0031] S3. Control the circulating pump 5 to pump the clear liquid to the heater 4 for heat exchange with the heated steam; the condensate formed by the heated steam is transported to the condensate tank 7; the clear liquid after heat exchange and heating flows into the separator 2. The circulating pump 5 pumps the clear liquid from the upper layer of the settling tank 3 to the heater 4. Inside the heater 4, the clear liquid undergoes indirect heat exchange with high-temperature steam from the steam compressor 6, causing its temperature to rise after absorbing heat. Since the clear liquid entering the heater 4 does not contain solid particles, it will not precipitate crystals due to the presence of seed crystals during the heat exchange process, nor will it allow solid particles to adhere, ensuring stable heat exchange efficiency and avoiding the scaling problem caused by solid-containing liquids directly entering the heater in traditional processes. The high-temperature steam releases heat in the heater 4 and condenses to form high-temperature condensate. This condensate is then subjected to vacuum flash evaporation to generate secondary steam, which is then sent to the preheater 1 to preheat the raw materials, achieving a cascaded recovery and utilization of the condensate waste heat. The heated clear liquid flows out of the heater 4 and into the separator 2.

[0032] S4. After heat exchange and heating, the clear liquid is mixed with the raw material and the reflux solid-containing liquid in the separator 2 and then flash-separated to obtain steam to obtain solid-containing concentrated liquid. The steam enters the steam compressor 6 and repeats steps S2 and S3. Part of the solid-containing concentrated liquid flows into the settling tank 3 and repeats the settling separation in step S2 and step S3. The other part flows out of the separator 2.

[0033] After the clarified liquid is heated by heat exchange, it enters separator 2. In separator 2, it is mixed with fresh raw material from preheater 1 and solid-containing liquid returned from settling tank 3, and then steam is generated by flash evaporation, which continuously concentrates the material in separator 2. Part of the solid-containing concentrate flows into settling tank 3, where it is separated again by settling. The settling separation step in S2 and the clarified liquid heat exchange and return step in S3 are repeated to form a cyclic concentration process. By controlling the return ratio of the solid-containing concentrate, the solid-liquid balance and concentration stability in the system are maintained, promoting crystal growth and improving separation efficiency. The other part of the solid-containing concentrate flows out from the bottom of separator 2 and enters the subsequent processing steps to achieve material concentration, crystallization and separation. The generated steam is repeatedly compressed and heated by the steam compressor. After being heated, the steam mixes and continues to flow into the heater to exchange heat with the clarified liquid.

[0034] In this embodiment, the raw material is preheated and then enters separator 2 for evaporation and separation. The steam is compressed and heated, then used as a heat source to enter heater 4. The solid-containing liquid is separated in settling tank 3, and the clear liquid enters heater 4 for heat exchange and heating. The solid-containing liquid is directly returned to separator 2. The clear liquid after heat exchange and heating is returned to separator 2 to mix and concentrate with the raw material and solid-containing liquid. Part of the concentrated solid-containing liquid is recycled and part is discharged. The entire process separates solid particles from the solid-containing liquid before it enters heater 4 through settling tank 3, ensuring that the material entering heater 4 is a clear liquid. This fundamentally reduces the source of scaling, effectively prevents scaling in heater 4, ensures stable heat exchange efficiency, reduces the frequency of downtime for cleaning, improves operating efficiency, and enhances system stability and continuity, while reducing maintenance costs and energy consumption. At the same time, the steam compression reuse and condensate waste heat recovery constitute a complete heat cycle, realizing a highly efficient and energy-saving evaporation and concentration process.

[0035] Please see Figure 2 , Figure 2 A flowchart of a second embodiment of the MVR evaporation process method provided by the present invention. In one embodiment, the step of conveying the condensate formed by the heat exchanged steam to the condensate tank 7 includes: S31. Control the condensate pump to pump the condensate to the condensate tank 7, and the condensate flashes in the condensate tank 7 to generate secondary steam. The condensate pump delivers the high-temperature condensate formed after heat exchange in heater 4 to condensate tank 7. Upon entering condensate tank 7, the pressure decreases from the high pressure in heater 4 to atmospheric or low pressure in condensate tank 7. Simultaneously, the low vacuum environment created by the steam compressor causes the saturation temperature of the condensate to drop, resulting in the instantaneous vaporization of some of the high-temperature condensate, generating flash steam. Through this flash process, the residual heat contained in the condensate that was originally intended for preheating in preheater 1 is further recovered and reused, re-entering the system as secondary steam, reducing heat loss and improving the system's thermal efficiency.

[0036] S32. The secondary steam, along with the steam flashed from the separator 2, is compressed and heated by the steam compressor 6 before flowing into the heater 4.

[0037] The secondary steam generated by flash evaporation enters the steam compressor 6 from the steam outlet of the condensate tank 7. After being compressed and heated by the steam compressor 6, it flows into the heater 4 and participates in the heat exchange process of the heater 4 as a heat source. Since this part of the flash steam and the steam generated by the separator 2 are combined and compressed and heated together at the inlet of the steam compressor 6, they can be reused without the need for additional equipment, further reducing the system's demand for external energy and improving overall energy efficiency.

[0038] S33. The condensate after flash evaporation is pumped to preheater 1 to preheat the raw materials.

[0039] In this embodiment, the condensate after flash evaporation flows out from the bottom of the condensate tank and enters the condensate pump through a pipeline. The condensate pump pressurizes and delivers the condensate to the preheater. After entering the preheater, the condensate indirectly exchanges heat with the raw materials flowing through it, transferring its own heat to the raw materials, thus raising their temperature and achieving the preheating effect. After releasing heat, the condensate cools down, forming low-temperature condensate, which is discharged from the preheater's condensate outlet or used for other purposes.

[0040] By pumping the condensate after flash evaporation to the preheater for preheating the raw materials, the residual heat contained in the condensate after flash evaporation is fully utilized. This recovers the waste heat from the condensate, which might otherwise be directly discharged, for raw material preheating, reducing the system's demand for external heat sources and lowering overall system energy consumption. Simultaneously, the condensate's temperature decreases after heat exchange with the raw materials in the preheater, reducing thermal pollution from high-temperature condensate discharge. The condensate pump provides stable power for condensate delivery, ensuring that the condensate enters the preheater at appropriate flow rates and pressures, making the preheating process stable and controllable, and avoiding instability in preheating effects caused by fluctuations in condensate flow.

[0041] In this embodiment, the high-temperature condensate formed after heat exchange in heater 4 is pumped to condensate tank 7 by a condensate pump. In condensate tank 7, flash evaporation occurs due to pressure reduction, generating steam. This steam is then compressed and heated by steam compressor 6 and reused in heater 4. This process effectively recovers the steam generated by the flash evaporation of condensate. The residual heat in the condensate is recovered as flash steam and reused as a heat source, reducing heat loss and improving the system's thermal efficiency. This further reduces system energy consumption and avoids the heat loss and increased circulating cooling water consumption caused by the traditional method of using a water ring vacuum pump to create negative pressure in the condensate tank. Compared to the increased energy consumption caused by the traditional method of using a water ring vacuum pump to create a vacuum in the condensate tank, the new process can save approximately 3% of energy.

[0042] Meanwhile, the condensate tank 7 acts as a buffer and storage for condensate, making the condensate delivery more stable and ensuring a stable supply of heat to the preheater 1.

[0043] In one embodiment, a gas scrubbing device is connected between the separator 2 and the steam compressor 6, and the step of steam entering the steam compressor 6 for compression and heating includes: S21. After the steam is cleaned by a gas scrubbing device to remove any liquid droplets it carries, it enters the steam compressor 6.

[0044] The steam generated by evaporation in separator 2 flows through a scrubbing device before entering the steam compressor 6. The scrubbing device removes droplets carried in the steam; its specific structure can be a wire mesh demister, a baffle plate demister, or a cyclone demister, etc. Taking a wire mesh demister as an example, it has an internal wire mesh layer woven from multiple layers of metal or plastic wire mesh. When steam carrying droplets passes through the wire mesh layer, the droplets are captured by impacting the wire mesh surface due to inertia, agglomerating into larger droplets, and then falling back to separator 2 under gravity. Because the droplets carried in the steam contain salt and solid impurities, if they directly enter the steam compressor 6, the water in the droplets will evaporate under the high temperature conditions inside the compressor, and the salt and impurities will precipitate and adhere to the compressor blades and casing surface, leading to scaling and corrosion of the compressor, affecting compression efficiency and equipment lifespan. By removing liquid droplets before the steam enters the compressor through the gas scrubbing device, the above-mentioned problems are avoided, ensuring the long-term stable operation of the steam compressor 6 and extending the service life of the equipment. At the same time, the clean steam enters the heater 4 for heat exchange after being compressed and heated, which also reduces the possibility of impurities entering the heater 4 and further reduces the risk of scaling in the heater 4.

[0045] Please see Figure 3 , Figure 3 A flowchart of a third embodiment of the MVR evaporation process method provided by the present invention, in which, in one embodiment, the step of another portion flowing out of separator 2 includes: S41. The solid-containing concentrate enters the thickener for thickening, and the thickened slurry enters the centrifuge for solid-liquid separation to obtain crystalline solid and centrifugal mother liquor. The solid-containing concentrate flowing from the bottom of separator 2 enters the thickener. The thickener is a vertical container with a conical bottom, and its interior is equipped with a guide tube and a stirring device. After entering the thickener through the feed inlet 11 at the top, the solid-containing concentrate slowly settles downwards under gravity. The guide tube guides the material to form a stable settling flow field, and the stirring device rotates at a low speed to prevent excessive accumulation of crystal slurry. During the settling process, the solid crystal particles in the solid-containing concentrate settle downwards under gravity and continuously accumulate at the conical bottom of the thickener, significantly increasing the solid content of the bottom crystal slurry and achieving a thickening effect. The mother liquor with a lower solid content in the upper layer is discharged from the overflow port at the top of the thickener and returned to separator 2 or the evaporation system to continue to participate in the circulation. At the same time, the thickener provides sufficient residence time and growth space for the crystals, allowing the crystals that have not yet fully grown to continue to grow in the mother liquor, further increasing the crystal size, which is beneficial for subsequent solid-liquid separation. After thickening and crystal growth, the high-concentration crystal slurry is discharged from the bottom of the thickener and enters a centrifuge for solid-liquid separation. The centrifuge separates the crystalline solid and liquid in the crystal slurry through centrifugal force generated by high-speed rotation, and obtains the crystalline solid product and centrifugal mother liquor.

[0046] S42. The centrifugal mother liquor is discharged outside the system and / or returned to separator 2 via a mother liquor pump.

[0047] The centrifugal mother liquor produced by centrifugation can be discharged from the system or returned to separator 2 via a mother liquor pump to re-enter the evaporation system, depending on the actual operating conditions. Alternatively, both paths can be configured simultaneously, with part discharged and part returned. When the centrifugal mother liquor still contains a high concentration of useful components, returning it to separator 2 for re-concentration in the evaporation system can further improve material recovery and reduce material loss. When the centrifugal mother liquor requires impurity removal, it is discharged from the system to remove impurities. By flexibly configuring the destination of the separated liquid, the system can adapt to different material characteristics and process requirements.

[0048] In this embodiment, the solid-containing concentrate flowing out of separator 2 first enters a thickener for thickening and crystal growth, allowing for sufficient crystal growth and increasing the solid content of the crystal slurry. Then, it enters a centrifuge for solid-liquid separation, yielding crystalline solids and centrifugal mother liquor. The centrifugal mother liquor is either discharged from the system or returned to separator 2 for re-evaporation, depending on the operating conditions. The thickening and crystal growth effects of the thickener increase the concentration of the crystal slurry and the crystal particle size entering the centrifuge, improving the solid-liquid separation efficiency and the purity of the crystalline solid product. The flexible reuse of the centrifugal mother liquor enables full material recovery or effective removal of impurities, improving the system's adaptability and resource utilization.

[0049] In one embodiment, the step of the clarified liquid flowing into separator 2 after heat exchange and heating includes: After heat exchange and heating, the clear liquid enters the separator 2 for flash evaporation, and flashes together with the material in the separator 2. The separated steam, together with the secondary steam flashed from the condensate tank, enters the steam compressor 6 for compression and heating.

[0050] After being heated by heat exchange, the clear liquid flows out of heater 4 and passes through a throttling device before entering separator 2. The throttling device is either a throttling valve 9 or an orifice plate, with an internal narrowing channel or adjustable valve core. The clear liquid is under high pressure in heater 4. When the clear liquid flows through the narrowing channel of the throttling device at a certain velocity, the flow cross-section suddenly decreases, the liquid velocity increases sharply, and the pressure drops abruptly. This process is an isenthalpic throttling process. Since the saturation temperature of the clear liquid decreases after the pressure drop, while the temperature of the clear liquid itself remains essentially constant before and after throttling, the clear liquid is in a superheated state after throttling. The excess heat causes some of the water in the clear liquid to vaporize instantaneously, producing flash steam. The clear liquid after throttling and flash vaporization is in a gas-liquid two-phase flow state and enters separator 2 directly from the outlet of the throttling device. After being throttled and flash-evaporated, the clarified liquid enters separator 2. Since some of the water has been pre-vaporized, the evaporation load in separator 2 is reduced, thereby improving the evaporation separation efficiency in separator 2. At the same time, the steam generated by flash evaporation enters steam compressor 6 together with the original steam in separator 2, increasing the intake air volume of steam compressor 6, which helps to improve the operating efficiency and heat recovery utilization rate of steam compressor 6. In addition, the pressure of the clarified liquid is reduced during the throttle flash evaporation process, and it is more compatible with the low-pressure environment in separator 2 after entering separator 2, reducing pressure fluctuations in separator 2 and contributing to the stability of system operation.

[0051] According to another aspect of the invention, please refer to Figure 4 and Figure 5 The present invention also provides an MVR evaporation system. The MVR evaporation system applies the above-mentioned MVR evaporation process. The MVR evaporation system includes a preheater 1, a separator 2, a settling tank 3, and a heater 4. The preheater 1 includes an inlet 11 and an outlet 12. The inlet 11 is used to supply raw materials. The separator 2 includes a first inlet 21, a second inlet 22, a third inlet 23, a first outlet 24, and a second outlet 25. The second outlet 25 is used to discharge the solid-containing concentrate. The settling tank 3 includes a settling inlet 31, an upper outlet 32, and a lower outlet 33. The first outlet 24 is connected to the settling inlet 31, and the lower outlet 33 is connected to the second inlet 22. The heater 4 includes a heating inlet 41 and a heating outlet 42. The heating inlet 41 and the upper outlet 32 ​​are connected through a circulation pump 5. The heating outlet 42 is connected to the third inlet 23. The outlet 12 is connected to the first inlet 21, or the outlet 12 is connected to the connecting pipe between the heating outlet 42 and the third inlet 23.

[0052] Specifically, the raw material enters through the feed inlet 11 of the preheater 1, and after exchanging heat with the high-temperature condensate from the heater 4 within the preheater 1, it flows out through the discharge outlet 12 of the preheater 1 and enters the first inlet 21 of the separator 2 through a pipeline. After entering the separator 2, the raw material evaporates and separates into steam and a solid-containing liquid within the separator 2. The steam enters the steam compressor 6 from the steam outlet of the separator 2, and after being compressed and heated, flows into the heater 4 as a heat source. The solid-containing liquid flows out from the first outlet 24 of the separator 2 and enters the settling inlet 31 of the settling tank 3 through a pipeline. After entering the settling tank 3, the solid-containing liquid undergoes gravity settling and separation within the settling tank 3 using the density difference between the solid particles and the liquid, forming a clear liquid and a solid-containing liquid in separate layers. The solid-containing liquid in the lower layer flows out from the lower outlet 33 of the settling tank 3 and enters the second inlet 22 of the separator 2 through a pipeline, flowing back to the separator 2 to participate in the subsequent evaporation process, and can also serve as a seed crystal to promote crystal growth. The clear liquid at the top layer flows out from the upper outlet 32 ​​of the settling tank 3 and is pumped to the heating inlet 41 of the heater 4 by the circulating pump 5. After entering the heater 4, the clear liquid undergoes indirect heat exchange with high-temperature steam from the steam compressor 6, and its temperature rises after absorbing heat. The high-temperature steam releases heat in the heater 4 and condenses to form high-temperature condensate, which is sent to the preheater 1 to preheat the raw materials. The clear liquid, after heat exchange and temperature rise, flows out from the heating outlet 42 of the heater 4 and enters the third inlet 23 of the separator 2 through a pipeline. After entering the separator 2, the clear liquid mixes and contacts with the raw materials entering from the first inlet 21 and the solid-containing liquid returning from the second inlet 22 to form a solid-containing concentrate. A portion of the solid-containing concentrate flows back into the settling tank 3 from the first outlet 24 of the separator 2, where it undergoes further settling and separation, and the above cycle is repeated; the other portion of the solid-containing concentrate flows out from the second outlet 25 of the separator 2 and enters the subsequent processing steps.

[0053] This embodiment, through the aforementioned structural connection, achieves sedimentation and separation of the solid-containing liquid in the settling tank 3 before entering the heater 4, allowing the clear liquid to enter the heater 4 for heat exchange while the solid-containing liquid directly returns to the separator 2. Since the clear liquid entering the heater 4 does not contain solid particles, scaling caused by induced crystallization in the heater 4 is avoided, and solid particle adhesion is also prevented, effectively preventing internal scaling of the heater 4, ensuring stable heat exchange efficiency, reducing the frequency of downtime for cleaning, improving the stability and continuity of system operation, and lowering maintenance costs and energy consumption. Simultaneously, the steam compression reuse and condensate waste heat recovery constitute a complete heat cycle, achieving a highly efficient and energy-saving evaporation and concentration process.

[0054] Please see Figure 4 and Figure 5In one embodiment, the MVR evaporation system further includes a steam compressor 6, the separator 2 includes a gas outlet 26, and the heater 4 includes a gas inlet 43. The gas outlet 26 and the gas inlet 43 are connected via the steam compressor 6. Steam generated from the evaporation of raw materials in the separator 2 flows out from the gas outlet 26 and enters the steam compressor 6 through a pipeline. The steam compressor 6 compresses the incoming steam, increasing its pressure and temperature, making it high-temperature steam with higher thermal energy. The compressed and heated high-temperature steam flows out from the outlet of the steam compressor 6 and enters the gas inlet 43 of the heater 4 through a pipeline, serving as a heat source for heating the clarified liquid. By compressing and heating the steam generated in the separator 2 and reusing it in the heater 4 using the steam compressor 6, the energy recovery of secondary steam is achieved. Steam that might otherwise be discharged or condensed is reused as a heat source, significantly reducing the system's dependence on external steam or electric heating and significantly reducing the overall energy consumption of the system. Simultaneously, the steam compression and reuse constitute a complete heat cycle, enabling the system to maintain operation based on its own generated steam after startup, achieving a highly efficient and energy-saving evaporation and concentration process.

[0055] Please see Figure 4 and Figure 5 In one embodiment, the MVR evaporation system further includes a condensate tank 7, and the heater 4 further includes a first condensate outlet 44, which is connected to the condensate tank 7. The preheater 1 further includes a condensate inlet 13 and a second condensate outlet 14, which are connected to the condensate tank 7 and used to discharge condensate. The heater 4 also includes a first condensate outlet 44, and the preheater 1 further includes a condensate inlet 13 and a second condensate outlet 14. The first condensate outlet 44 of the heater 4 is connected to the inlet of the condensate tank 7 via a pipeline, and the outlet of the condensate tank 7 is connected to the condensate inlet 13 of the preheater 1 via a pipeline.

[0056] The high-temperature condensate formed by the condensation of high-temperature steam released heat in heater 4 flows out from the first condensate outlet 44 of heater 4 and enters the condensate tank 7 through pipelines. After entering the condensate tank 7, the pressure decreases from the high pressure state in heater 4 to the normal or low pressure state in condensate tank 7, causing the saturation temperature of the condensate to drop accordingly. This results in some of the high-temperature condensate instantly vaporizing, generating flash steam. The flash steam enters the steam compressor 6 from the steam outlet of condensate tank 7, is compressed and heated, and then reused in heater 4, further recovering the waste heat from the condensate. The remaining condensate in condensate tank 7 flows out from the outlet of condensate tank 7 and enters the condensate inlet 13 of preheater 1 through pipelines, serving as a heat source for preheating raw materials. The condensate undergoes indirect heat exchange with the raw materials in preheater 1, transferring heat to the raw materials and then lowering its own temperature to form low-temperature condensate, which is discharged from the second condensate outlet 14 of preheater 1 or used for other purposes.

[0057] By incorporating a condensate tank 7, the high-temperature condensate undergoes flash evaporation before entering the preheater 1, further recovering and utilizing the residual heat in the condensate as flash steam. This reduces heat loss and improves the system's thermal energy utilization rate. Simultaneously, the condensate tank 7 acts as a buffer for the condensate, ensuring a smoother condensate flow and a stable heat source supply to the preheater 1. This avoids the problem of unstable preheating effects caused by fluctuations in condensate flow.

[0058] Furthermore, the outlet 12 of the preheater 1 is directly connected to the first inlet 21 of the separator 2 via an independent pipeline. The raw material enters from the inlet 11 of the preheater 1, exchanges heat with the high-temperature condensate from the heater 4 within the preheater 1, and then flows out from the outlet 12 of the preheater 1, entering the separator 2 through the first inlet 21 of the separator 2 via an independent pipeline. Because the raw material enters the separator 2 directly through an independent pipeline, its flow path is independent of the clear liquid return pipeline and is not affected by the clear liquid return flow rate and pressure. Therefore, the raw material feed flow rate can be precisely adjusted by an independent control valve, without interfering with the clear liquid return circulation flow rate. This allows the system to independently control the feed rate and circulation rate according to actual processing needs, improving the system's operational flexibility and control accuracy. Meanwhile, the raw material enters the separator 2 through an independent inlet and mixes with the clear liquid that has been heated by heat exchange and entered through the third inlet 23 inside the separator 2. This avoids heat loss caused by the two materials at different temperatures mixing in the pipeline in advance, allowing the raw material to enter the separator 2 directly at the preheated temperature to participate in evaporation, which is beneficial to improving the efficiency of thermal energy utilization.

[0059] Furthermore, the outlet 12 of the preheater 1 is connected to the heating outlet 42 of the heater 4 and the third inlet 23 of the separator 2 via a connecting pipe. The raw material enters from the inlet 11 of the preheater 1, undergoes heat exchange and heating within the preheater 1, and then flows out from the outlet 12 of the preheater 1, converging into the pipe connecting the outlet of the heater 4 to the third inlet 23 of the separator 2. It mixes with the heated clear liquid and then enters the separator 2 together through the third inlet 23. Because the raw material and the heated clear liquid are pre-mixed before entering the separator 2, the temperature of the mixed material is more uniform, resulting in less impact on the temperature and pressure within the separator 2. This facilitates the smooth operation of the evaporation and separation process within the separator 2, reduces temperature and pressure fluctuations caused by the direct entry of cold material, and improves the stability of the system operation.

[0060] Furthermore, the MVR evaporation system also includes a thickener and a centrifuge. The second outlet 25 of separator 2 is connected to the thickener, and the thickener is connected to the centrifuge. The solid-containing concentrate flowing out of the second outlet 25 of separator 2 enters the thickener through a pipeline. The thickener is a vertical container with a conical bottom. After entering the thickener, the solid-containing concentrate slowly settles downwards under gravity. The solid crystal particles in the concentrate gather towards the conical bottom of the thickener under gravity, gradually increasing the solid content of the bottom crystal slurry and achieving a thickening effect. At the same time, the thickener provides sufficient residence time for the crystals, allowing crystals that have not yet fully grown to continue to grow in the mother liquor, further increasing the crystal size. The upper layer of mother liquor with a lower solid content is discharged from the overflow port at the top of the thickener and returned to separator 2 or the evaporation system to continue circulating. The high-concentration crystal slurry after thickening and crystal growth is discharged from the bottom of the thickener and enters the centrifuge through a pipeline. The centrifuge rotates at high speed, generating centrifugal force to separate the crystalline solids and liquids in the slurry, yielding the crystalline solid product and centrifugal mother liquor. The centrifugal mother liquor can be discharged from the system or returned to separator 2 via a feed pump to re-enter the evaporation system, depending on the actual operating conditions. Alternatively, both paths can be set simultaneously, with part discharged and part returned.

[0061] Through the thickening and crystal growth effects of the thickener, crystals in the solid-containing concentrate are fully grown, significantly increasing the solid content of the crystal slurry. This results in higher solid-liquid separation efficiency after entering the centrifuge, improving the purity and yield of the crystalline solid product. Simultaneously, the flexible reuse of the separated liquid allows the system to adjust the process route according to material characteristics. When the centrifuged mother liquor still contains a high concentration of useful components, it is returned to the evaporation system for further concentration, improving material recovery. When the centrifuged mother liquor is waste liquid requiring impurity removal, it is discharged from the system, achieving impurity removal and improving the system's adaptability and resource utilization.

[0062] Furthermore, the preheater 1 can be a shell-and-tube heat exchanger, a plate heat exchanger, etc. When a shell-and-tube heat exchanger is used, the raw material flows inside the heat exchange tubes, and the high-temperature condensate flows in the shell side outside the heat exchange tubes, achieving indirect heat exchange through the heat exchange tube walls. Shell-and-tube heat exchangers are robust, pressure-resistant, and highly adaptable, suitable for processing materials with large flow rates or containing small amounts of impurities. When a plate heat exchanger is used, the raw material and high-temperature condensate flow alternately between multiple layers of corrugated plates, achieving indirect heat exchange through the plates. Plate heat exchangers have high heat transfer coefficients, compact structures, small footprints, and the plates are easy to disassemble and clean, making them suitable for scenarios requiring frequent maintenance. Both types of heat exchangers can achieve efficient heat exchange between the raw material and the high-temperature condensate, fully utilizing the waste heat of the condensate to preheat the raw material, reducing the temperature difference between the raw material entering the separator 2 and the temperature inside the separator 2, reducing the heat input required for evaporation inside the separator 2, thereby reducing the load on the steam compressor 6 and reducing the overall energy consumption of the system. Users can flexibly choose the specific type of preheater 1 based on factors such as material characteristics, processing scale, installation space and maintenance requirements, so that the system can achieve good preheating effect and energy efficiency in different application scenarios.

[0063] Furthermore, the heater 4 is preferably a plate heat exchanger. Tubular heat exchangers have wide flow channels and can handle materials containing solid particles, high viscosity, and easy crystallization; while plate heat exchangers have narrow flow channels, making them unsuitable for long-term processing of materials containing solids and prone to scaling and clogging. In this embodiment, the circulating liquid is a clear liquid, eliminating scaling impurities and fine crystal formation. Therefore, a plate heat exchanger can be used for heating. Compared to traditional tubular heat exchangers and novel steam-to-steam heat exchangers, the steam-liquid heat transfer efficiency of plate heat exchangers is significantly increased, while effectively reducing floor space and material costs, thus lowering project investment costs.

[0064] Furthermore, regarding the selection of the circulating pump 5, since the ratio of circulating liquid to steam in traditional forced circulation evaporators reaches several hundred to several thousand, a high-flow-rate pump, such as a traditional axial flow pump, is required. However, in this embodiment, the ratio of circulating liquid to tonnes of evaporated water is significantly reduced, allowing the introduction of a low-flow-rate pump, such as a traditional centrifugal pump. Simultaneously, the head of the centrifugal pump can be increased, resulting in a greater increase in the circulating liquid temperature and improved thermal efficiency. In addition, the greater increase in circulating liquid temperature further reduces the circulating liquid flow rate. Due to the increased head and greater temperature rise in the circulating liquid, the saturated solubility of the circulating liquid is high, which can desaturate the supersaturated state and prevent evaporation within the heater 4, further reducing the possibility of scaling.

[0065] Please see Figure 4 and Figure 5In one embodiment, the inlet of the steam compressor 6 is connected to the condensate tank 7, and a regulating valve 8 is provided between the steam compressor 6 and the condensate tank 7. The regulating valve 8 is used to control the flow rate of flash steam from the condensate tank 7 into the steam compressor 6. When the amount of flash steam in the condensate tank 7 is large, the opening of the regulating valve 8 increases, allowing more flash steam to enter the steam compressor 6 for reuse; when the amount of flash steam is small, the opening of the regulating valve 8 decreases to prevent excessive low-pressure steam from entering the steam compressor 6 and affecting its operational stability. Through the precise control of the regulating valve 8, the mixing ratio of the steam generated by the separator 2 and the flash steam from the condensate tank 7 can be balanced, keeping the steam parameters at the inlet of the steam compressor 6 stable and ensuring that the steam compressor 6 operates under high-efficiency conditions.

[0066] By introducing the flash steam from the condensate tank 7 into the steam compressor 6 for reuse, the waste heat in the condensate is further recovered, heat loss is reduced, and the system's thermal energy utilization efficiency is improved. Simultaneously, the regulating valve 8 allows for flexible adjustment of the flash steam inflow according to actual operating conditions, avoiding the impact of flash steam fluctuations on the operational stability of the steam compressor 6 and ensuring stable system operation.

[0067] Furthermore, the regulating valve 8 is intelligently interlocked with the current and vibration displacement measurements of the steam compressor 6, which can effectively prevent compressor surge and achieve intelligent, stable, and long-cycle operation of the system.

[0068] Please see Figure 4 and Figure 5 In one embodiment, a throttling valve 9 is provided between the heating outlet 42 and the third inlet 23. After the clarified liquid is heated by heat exchange, it flows out of the heating outlet 42 of the heater 4, first flows through the throttling valve 9, and then enters the third inlet 23 of the separator 2 through the pipeline.

[0069] The throttling valve 9 has an adjustable valve core, which regulates the fluid pressure and flow rate by changing the flow area between the valve core and the valve seat. The clarified liquid, after heat exchange and heating, is under high pressure in the heater 4. When the clarified liquid flows through the throttling valve 9, the flow area suddenly decreases, the liquid velocity increases sharply, and the pressure drops abruptly; this process is an isenthalpic throttling process. Since the saturation temperature of the clarified liquid decreases with the pressure reduction, while the temperature of the clarified liquid itself remains essentially unchanged before and after throttling, the clarified liquid is in a superheated state after throttling. The excess heat causes some of the water in the clarified liquid to vaporize instantaneously, producing flash steam. The clarified liquid after throttling and flashing is in a gas-liquid two-phase flow state and enters the separator 2 directly from the outlet of the throttling valve 9.

[0070] By setting a throttling valve 9, the clarified liquid undergoes flash evaporation before entering separator 2, causing some water to vaporize prematurely. This reduces the evaporation load within separator 2, improving its evaporation separation efficiency. Simultaneously, the steam generated from flash evaporation, along with the existing steam in separator 2, enters steam compressor 6, increasing its intake air volume and improving its operating efficiency and heat recovery rate. Furthermore, the throttling valve 9 can regulate the flow rate of clarified liquid entering separator 2, controlling the circulation volume according to system operating requirements, ensuring stable system operation under different load conditions. The throttling valve 9 also prevents sudden decompression within separator 2 that could lead to explosive boiling, promoting smooth system operation. The removal of fine crystals in the settling tank 3 reduces wear on the throttling valve 9 and prevents excessive small crystal formation in the finished product due to large amounts of fine crystal reflux, thus promoting the formation of larger crystals.

[0071] The above are merely exemplary embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of protection of the present invention.

Claims

1. An MVR evaporation process method, characterized in that, The MVR evaporation process includes the following steps: S1. Control the feed pump to pump the raw material to the preheater, and the raw material enters the separator after heat exchange and temperature rise in the preheater. S2. The raw material is flash-separated in the separator to form steam and solid-containing liquid; the steam enters the steam compressor for compression and heating, and the heated steam flows into the heater; the solid-containing liquid flows from the upper part of the separator into the settling tank for settling and separation to form clear liquid and solid-containing liquid in upper and lower layers, and the solid-containing liquid is returned to the separator. S3. Control the circulating pump to pump the clear liquid to the heater, where it exchanges heat with the heated steam; the condensate formed by the heated steam is transported to the condensate tank; the heated clear liquid flows into the separator. S4. After heat exchange and heating, the clear liquid is mixed with the raw material and the reflux solid-containing liquid in the separator, and then the steam is separated by flash evaporation to obtain a solid-containing concentrate. The steam enters the steam compressor to repeat steps S2 and S3. A portion of the solid-containing concentrate flows into the settling tank, and the settling separation in step S2 and step S3 are repeated. The other portion flows out of the separator.

2. The MVR evaporation process method as described in claim 1, characterized in that, The step of conveying the condensate formed by the heat-exchanged steam to the condensate tank includes: S31. Control the condensate pump to pump the condensate to the condensate tank, and the condensate flashes in the condensate tank to generate secondary steam. S32. The secondary steam, together with the steam flashed out of the separator, is compressed and heated by the steam compressor and then flows into the heater. S33. The condensate after flash evaporation is pumped to the preheater to preheat the raw materials.

3. The MVR evaporation process method as described in any one of claims 1 or 2, characterized in that, A gas scrubbing device is connected between the separator and the steam compressor. The step of the steam entering the steam compressor for compression and heating includes: S21. The steam enters the steam compressor after the air washing device removes the liquid droplets it carries.

4. The MVR evaporation process method as described in claim 1, characterized in that, The step of the other portion flowing out of the separator includes: S41. The solid-containing concentrate enters a thickener for thickening, and the thickened slurry enters a centrifuge for solid-liquid separation to obtain crystalline solid and centrifugal mother liquor. S42. The centrifugal mother liquor is discharged outside the system and / or returned to the separator via the mother liquor pump.

5. The MVR evaporation process method according to any one of claims 1 or 2, characterized in that, The step of the clarified liquid flowing into the separator after heat exchange and heating includes: The clarified liquid, after being heated by heat exchange, enters the separator for flash evaporation.

6. An MVR evaporation system, wherein the MVR evaporation system applies the MVR evaporation process method according to any one of claims 1 to 5, characterized in that, include: A preheater, comprising an inlet and an outlet, wherein the inlet is used to supply raw materials; A separator, comprising a first inlet, a second inlet, a third inlet, a first outlet, and a second outlet, wherein the second outlet is used to discharge a concentrated liquid containing solids; A settling tank, comprising a settling inlet, an upper outlet, and a lower outlet, wherein the first outlet is connected to the settling inlet, and the lower outlet is connected to the second inlet; A heater, comprising a heating inlet and a heating outlet, wherein the heating inlet and the upper outlet are connected by a circulation pump, the heating outlet is connected to the third inlet, and the discharge outlet is connected to the first inlet, or the discharge outlet is connected to the connecting pipeline of the heating outlet and the third inlet; The steam compressor, the separator further includes a gas outlet, the heater further includes a gas inlet, and the gas outlet and the gas inlet are connected through the steam compressor; The heater further includes a condensate tank and a first condensate outlet connected to the condensate tank. The preheater also includes a condensate inlet and a second condensate outlet connected to the condensate tank, and the second condensate outlet is used to discharge condensate.

7. The MVR evaporation system as described in claim 6, characterized in that, The MVR evaporation system also includes a thickener and a centrifuge, with the second outlet of the separator connected to the thickener and the thickener connected to the centrifuge.

8. The MVR evaporation system as described in claim 7, characterized in that, The heater is a plate heat exchanger.

9. The MVR evaporation system as described in claim 8, characterized in that, The inlet branch of the steam compressor is connected to the condensate tank, and a regulating valve is provided between the steam compressor and the condensate tank.

10. The MVR evaporation system according to any one of claims 6 to 9, characterized in that, A throttling valve is provided between the heating outlet and the third inlet.

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