Forced circulation MVR (Mechanical Vapor Recompression) evaporation crystallizer

Abstract

The utility model discloses a forced circulation MVR (Mechanical Vapor Recompression) evaporation crystallizer which comprises a feeding pump; the circulating separation assembly comprises a heater, a separation unit, a circulating pump and a discharging pump; the solid-liquid separation assembly is used for carrying out solid-liquid separation on the material discharged by the discharge pump, discharging the separated solid out of the system, discharging one part of mother liquor out of the system, and returning the other part of mother liquor to the circulating separation assembly; a compressor; the condensation assembly comprises a condensation water tank and a condensation water pump, the condensation water pump is provided with two output ends, one output end is communicated with the outside, and the other output end is connected with the solid-liquid separation assembly and the circulation separation assembly; the negative pressure assembly comprises a vacuum pump. According to the forced circulation MVR evaporation crystallizer, one output end of the condensate pump in the condensation assembly is connected with the solid-liquid separation assembly and the circulation separation assembly, so that the condensate pump conveniently washes and cleans the interior of a pipeline through condensate water in a condensate water tank, impurities such as crystal precipitates are removed, pipe blockage is avoided, and normal operation of evaporation and concentration is guaranteed.

Description

TECHNICAL FIELD

[0001] The utility model relates to MVR evaporation crystallizer especially is related to a kind of forced circulation MVR evaporation crystallizer. BACKGROUND

[0002] MVR evaporation crystallizer is evaporated using evaporation system, using MVR evaporation process, evaporates and crystallizes the equipment to material, its working principle is using the secondary steam generated in evaporator, these steam is compressed after steam compressor, its pressure, temperature rises, hot haze increases, then it is sent back to the heating chamber of evaporator when as heating steam use, make the liquid of processing continue to boil evaporation, and heating steam itself is condensed into water and discharged from system, since recovering latent heat, it saves a large amount of heat energy, improves heat efficiency, reduces the demand to external heating and cooling resources, with the advantages of reducing energy consumption, high efficiency, environmental protection, energy saving and widely used.

[0003] MVR evaporation crystallizer in prior art, mostly like the MVR evaporation crystallizer disclosed in Chinese patents CN118576991A, CN214735134U, although latent heat can be used to save energy consumption, but, after long-term operation, pipe interior is prone to accumulate crystallization, precipitate and other residual impurities, leading to pipe blockage occurs, affect the normal operation of evaporation concentration;Not only this, feed pump and separator are usually only provided with single feed pipeline, for conveying material to separator, leading to when feed pipeline fails, need to stop running, difficult to realize long-term continuous separation, reduce production efficiency.

[0004] Therefore, it is necessary to improve MVR evaporation crystallizer in prior art. INVENTION CONTENTS

[0005] The utility model aims at overcoming the defects in prior art, and provide a kind of forced circulation MVR evaporation crystallizer that prevents pipe blockage and improves production efficiency.

[0006] To realize the above technical effect, the technical scheme of the utility model is as follows: a kind of forced circulation MVR evaporation crystallizer, comprising:

[0007] feed pump;

[0008] circulation separation component, the circulation separation component includes heater, separator unit, circulating pump and discharge pump, the heater has material inlet, material outlet, heating steam inlet and condensate outlet, the separator unit has separation inlet, concentrated liquid outlet and pure steam outlet, the heating steam inlet is used to connect live steam source, the input end of the feed pump is communicated with the material inlet, the material outlet is communicated with the separation inlet, the concentrated liquid outlet is communicated with the input end of the discharge pump by the circulating pump and the material inlet, and the concentrated liquid outlet is communicated with the input end of the discharge pump.

[0009] a solid-liquid separation assembly for separating the material discharged by the discharge pump into solid and liquid, discharging the separated solid out of the system, discharging a part of the mother liquor out of the system, and returning the other part of the mother liquor to the circulating separation assembly;

[0010] a compressor having a compressed steam inlet connected to the pure steam outlet and a compressed steam outlet connected to the heated steam inlet;

[0011] a condensing assembly including a condensing water tank and a condensing water pump, the condensing water tank being connected between the condensing water outlet and the input end of the condensing water pump, the condensing water pump having two output ends, one of which is connected to the outside and the other of which is connected to the solid-liquid separation assembly and the circulating separation assembly, both of the output ends being connected to a switch valve;

[0012] a negative pressure assembly including a vacuum pump, the input end of the vacuum pump being connected to the condensing water tank and the output end being connected to the outside.

[0013] Preferably, in order to facilitate the discharge of non-condensable gas, the negative pressure assembly further includes a non-condensable gas separator having a mixing inlet, a liquid discharge outlet and a gas discharge outlet, the mixing inlet being connected to the condensing water tank, the liquid discharge outlet being connected to the input end of the condensing water pump, and the gas discharge outlet being connected to the input end of the vacuum pump.

[0014] Preferably, in order to facilitate the discharge of non-condensable gas in the heater, the heater has a mixing outlet connected to the mixing inlet.

[0015] Preferably, in order to cool the non-condensable gas discharged by the separator, a non-condensable gas cooler is further provided between the non-condensable gas separator and the heater, the non-condensable gas cooler having a cooling inlet and a cooling outlet for passing in and discharging cooling water, and a cooling inlet and a cooling outlet for passing in and discharging cooling water, the mixing outlet, the cooling inlet, the cooling outlet and the mixing inlet being connected in sequence.

[0016] Preferably, in order to improve the recovery rate of the solute, the discharge of the secondary steam after crystallization, the separation assembly includes an evaporation separator and a secondary separator, the separation inlet and the concentrated liquid outlet are provided on the evaporation separator, the pure steam outlet is provided on the secondary separator, the evaporation separator further has a secondary steam outlet and a reflux inlet, the secondary separator further has a secondary steam inlet and a reflux outlet, the reflux outlet is connected to the reflux inlet, and the secondary steam inlet is connected to the secondary steam outlet.

[0017] Preferably, in order to realize solid-liquid separation, the solid-liquid separation assembly comprises a head tank, a centrifuge, a mother liquor tank and a mother liquor pump, the head tank is provided with a crystal slurry inlet, a crystal slurry outlet and an overflow, the centrifuge is provided with a centrifugal inlet, a solid outlet and a mother liquor outlet, the output end of the discharge pump is communicated with the crystal slurry inlet, the crystal slurry outlet is communicated with the centrifugal inlet, the solid outlet is communicated with the outside, the overflow is communicated with the mother liquor tank, the mother liquor outlet is communicated with the input end of the mother liquor pump, and the output end of the mother liquor pump is communicated with the material inlet and the outside.

[0018] Preferably, in order to realize flushing cleaning of the pipeline, one of the output ends of the condensate pump is communicated with five branch pipes, the five branch pipes are respectively communicated between the output end of the discharge pump and the crystal slurry inlet, between the crystal slurry outlet and the centrifugal inlet, between the overflow and the mother liquor tank, between the input end of the mother liquor pump and the mother liquor tank, and between the output end of the mother liquor pump and the outside, and a cleaning valve is arranged on each branch pipe.

[0019] Preferably, in order to realize preheating of the material, the condensing assembly further comprises a condensate preheater, the condensate preheater is provided with a condensing inlet, a condensing outlet, a preheating inlet and a preheating outlet, the condensing inlet is communicated with the other output end of the condensate pump, the condensing outlet is used for being communicated with the outside, and the output end of the feed pump is communicated with the material inlet in sequence through the preheating inlet and the preheating outlet.

[0020] Preferably, in order to facilitate continuous operation of the device, the feed pump has two output ends and is connected with switching valves, one of the two output ends of the feed pump is communicated with the preheating inlet, and the other is communicated with the material inlet.

[0021] Preferably, in order to improve the compression effect of the secondary steam, the compressor is a single-screw compressor.

[0022] In summary, compared with the prior art, the forced circulation MVR evaporation crystallizer of the utility model is characterized in that one of the output ends of the condensate pump in the condensing assembly is connected with the solid-liquid separation assembly and the circulation separation assembly, the condensate pump facilitates flushing cleaning of the inside of the pipeline with condensate in the condensate tank, removes sundries such as crystallization deposits, avoids pipe blockage, and guarantees normal operation of evaporation and concentration. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the utility model;

[0024] Figure 2 It is a structural schematic diagram of the device for processing material;

[0025] Figure 3It is the structure schematic view of the device for treating condensate water of the utility model;

[0026] Figure 4 It is the structure schematic view of the device for using condensate water to flush and clean of the utility model;

[0027] In the figure: 1, feed pump;101, switching valve;2, heater;201, material inlet;202, material outlet;203, heating steam inlet;204, condensate water outlet;205, mixed outlet;3, evaporation separator;301, separation inlet;302, concentrated liquid outlet;303, secondary steam outlet;304, reflux inlet;4, secondary separator;401, pure steam outlet;402, secondary steam inlet;403, reflux outlet;5, compressor;501, compressed steam inlet;502, compressed steam outlet;503, spray water inlet;504, drain port;6, condensate tank;7, condensate pump;701, on-off valve;8, vacuum pump;9, non-condensable gas separator;901, mixed inlet;902, liquid discharge port;903, gas discharge port;10, non-condensable gas cooler;1001, cooling inlet;1002, cooling outlet;1003, cooling inlet;1004, cooling outlet;11, high tank;1101, crystal slurry inlet;1102, crystal slurry outlet;1103, overflow port;12, centrifuge;1201, centrifugal inlet;1202, solid outlet;1203, mother liquor outlet;13, mother liquor tank;14, mother liquor pump;15, branch pipe;1501, cleaning valve;16, condensate preheater;1601, condensing inlet;1602, condensing outlet;1603, preheating inlet;1604, preheating outlet;17, spray pump;18, spray water cooler;1801, spray inlet;1802, spray outlet;1803, circulation inlet;1804, circulation outlet;19, circulation pump;20, discharge pump. DETAILED DESCRIPTION

[0028] The specific embodiments of the utility model are further described below in combination with the drawings and examples. The following examples are only used to more clearly illustrate the technical scheme of the utility model, and cannot limit the protection scope of the utility model.

[0029] As Figures 1-4 Indicated, a kind of forced circulation MVR evaporation crystallizer, including:

[0030] Feed pump 1;

[0031] The circulating separation assembly comprises a heater 2, a separation unit, a circulating pump 19 and a discharge pump 20, the heater 2 has a material inlet 201, a material outlet 202, a heating steam inlet 203 and a condensed water outlet 204, the separation unit has a separation inlet 301, a concentrated liquid outlet 302 and a pure steam outlet 401, the heating steam inlet 203 is used for connecting a live steam source, the input end of the feed pump 1 is communicated with the material inlet 201, the material outlet 202 is communicated with the separation inlet 301, the concentrated liquid outlet 302 is communicated with the material inlet 201 through the circulating pump 19, and the concentrated liquid outlet 302 is communicated with the input end of the discharge pump 20;

[0032] The solid-liquid separation assembly is used for solid-liquid separation of the material discharged by the discharge pump 20, and separated solids are discharged from the system, part of the mother liquor is discharged from the system, and the other part is returned to the circulating separation assembly;

[0033] The compressor 5 has a compressed steam inlet 501 communicated with the pure steam outlet 401 and a compressed steam outlet 502 communicated with the heating steam inlet 203;

[0034] The condensing assembly comprises a condensed water tank 6 and a condensed water pump 7, the condensed water tank 6 is communicated between the condensed water outlet 204 and the input end of the condensed water pump 7, the condensed water pump 7 has two output ends, one of which is communicated with the outside world, and the other is connected with the solid-liquid separation assembly and the circulating separation assembly, and both output ends are connected with the switch valve 701;

[0035] The negative pressure assembly comprises a vacuum pump 8, the input end of the vacuum pump 8 is communicated with the condensed water tank 6, and the output end is communicated with the outside world.

[0036] When the device is running, the feed pump 1 is started, and the feed liquid to be concentrated is transported into the heater 2 through the material inlet 201, and the feed liquid flows upward in the pipe of the heater 2, exchanges heat with the live steam (or compressed secondary steam) in the heater 2, and is discharged from the material outlet 202 after the temperature is increased, enters the separation unit through the separation inlet 301, and is boiled and evaporated in the negative pressure environment of the separation unit to generate secondary steam, and the concentration of the material is increased and discharged through the concentrated liquid outlet 302, and under the action of the circulating pump 19, the circulating pump 19 is introduced into the heater 2 and exchanges heat with the steam in the heater 2, so that the concentration of the feed liquid continues to increase, and circulates between the heater 2 and the separation unit, and when the concentration of the feed liquid increases to a certain extent, the crystal slurry formed after concentration is introduced into the solid-liquid separation assembly through the discharge pump 20, the crystal slurry is subjected to solid-liquid separation through the solid-liquid separation assembly, and the mixture is divided into two parts, one part is a crystal solid, and the crystal solid is directly discharged out of the system, and the other part is a mother liquor, which is divided into two parts, one part is discharged from the system, and the other part is introduced into the circulating pipeline of the separation unit and the heater 2 again to be concentrated and evaporated to improve the solute recovery rate.

[0037] During the concentration process of the feed liquid, the secondary steam generated is introduced into the compressor 5 through the compressed steam inlet 501, the secondary steam is compressed by the compressor 5 to increase the temperature and heat of the compressed steam, and the compressed secondary steam is discharged through the compressed steam outlet 502 and enters the heater 2 through the heating steam inlet 203 to exchange heat with the feed liquid flowing in the heater 2, so that the live steam is not continuously introduced into the heater 2, the originally wasted steam is fully utilized, the latent heat is recovered, the thermal efficiency is improved, and the production cost is reduced. In the embodiment, the compressor 5 preferably adopts a single-screw compressor 5, which can significantly increase the temperature increase of the compressed secondary steam. After the secondary steam is compressed, the temperature can be increased by about 18°C, which facilitates the compressed steam to enter the heater 2 again to continue to heat the circulating feed liquid.

[0038] In the heater 2, the steam (including live steam and compressed secondary steam) exchanges heat with the feed liquid and the temperature decreases to form condensed water, which is discharged from the condensed water outlet 204 and collected in the condensed water tank 6. The input end of the condensed water pump 7 is communicated with the condensed water tank 6, which facilitates the extraction of the condensed water in the condensed water tank 6. The condensed water pump 7 has two output ends and both of them are connected with the switch valve 701, which can select one to be opened and the other to be closed according to the actual needs, so as to discharge the condensed water from the system or introduce the condensed water into the solid-liquid separation assembly and the circulating separation assembly to flush and clean the inside of the pipeline through which the feed liquid flows in the solid-liquid separation assembly and the circulating separation assembly, remove the impurities such as crystallization and sediment attached to the inner wall of the pipeline, and ensure that the feed liquid can smoothly pass through the above-mentioned pipeline in the subsequent evaporation and concentration process, thereby ensuring the normal and stable operation of the evaporation and concentration.

[0039] In the evaporation concentration process, the non-condensable gas such as air mixed in the secondary steam will not be condensed. These non-condensable gases enter the heater 2, and are discharged out of the system under the action of the vacuum pump 8.

[0040] Further improvement is that the negative pressure assembly further includes a non-condensable gas separator 9, the non-condensable gas separator 9 has a mixed inlet 901, a liquid discharge port 902 and an exhaust port 903, the mixed inlet 901 is communicated with the condensate tank 6, the liquid discharge port 902 is communicated with the input end of the condensate pump 7, and the exhaust port 903 is communicated with the input end of the vacuum pump 8; the heater 2 has a mixed outlet 205, and the mixed outlet 205 is communicated with the mixed inlet 901.

[0041] In the heater 2, the mixed gas containing non-condensable gas is discharged through the mixed outlet 205, enters the non-condensable gas separator 9 through the mixed inlet 901, and is subjected to gas-liquid separation by the non-condensable gas separator 9, the non-condensable gas is discharged through the exhaust port 903, and the separated water is discharged through the liquid discharge port 902 by the condensate pump 7.

[0042] Further improvement is that the non-condensable gas separator 9 and the heater 2 are further provided with a non-condensable gas cooler 10, the non-condensable gas cooler 10 has a cooling inlet 1001, a cooling outlet 1002, a cooling inlet 1003 and a cooling outlet 1004, the cooling inlet 1001 and the cooling outlet 1002 are used for introducing cooling water and discharging cooling water respectively, and the mixed outlet 205, the cooling inlet 1003, the cooling outlet 1004 and the mixed inlet 901 are sequentially communicated.

[0043] The non-condensable gas discharged from the non-condensable gas separator 9 has a relatively high temperature, and is introduced into the non-condensable gas cooler 10 through the cooling outlet 1004, while the circulating cooling water is introduced into the non-condensable gas cooler 10 from the cooling inlet 1001, exchanges heat with the non-condensable gas, and is discharged from the cooling outlet 1004 after the temperature of the non-condensable gas is reduced, while the circulating cooling water is discharged from the cooling outlet 1002.

[0044] Further improvement is that the separation unit includes an evaporation separator 3 and a secondary separator 4, the separation inlet 301 and the concentrated liquid outlet 302 are arranged on the evaporation separator 3, the pure steam outlet 401 is arranged on the secondary separator 4, the evaporation separator 3 is further provided with a secondary steam outlet 303 and a reflux inlet 304, the secondary separator 4 is further provided with a secondary steam inlet 402 and a reflux outlet 403, the reflux outlet 403 is communicated with the reflux inlet 304, and the secondary steam inlet 402 is communicated with the secondary steam outlet 303.

[0045] The liquid solution is evaporated and boiled in the evaporation separator 3, and the concentration is increased, and the secondary steam is generated, and the secondary steam is mixed with the liquid drops to form the mixed gas, which is discharged through the secondary steam outlet 303, enters the secondary separator 4 through the secondary steam inlet 402, and is separated to generate the clean secondary steam, which is discharged through the pure steam outlet 401 and enters the compressor 5, and the liquid drops are accumulated in the secondary separator 4 and are discharged through the backflow outlet 403 and introduced into the evaporation separator 3 through the backflow inlet 304 to be concentrated and evaporated again, so that the recovery rate of the solute is improved, and finally the high-concentration crystal slurry is formed and discharged through the discharge pump 20 and introduced into the solid-liquid separation assembly for solid-liquid separation.

[0046] Further improvement is that the solid-liquid separation assembly comprises a head tank 11, a centrifuge 12, a mother liquor tank 13 and a mother liquor pump 14, the head tank 11 has a crystal slurry inlet 1101, a crystal slurry outlet 1102 and an overflow port 1103, the centrifuge 12 has a centrifugal inlet 1201, a solid outlet 1202 and a mother liquor outlet 1203, the output end of the discharge pump 20 is communicated with the crystal slurry inlet 1101, the crystal slurry outlet 1102 is communicated with the centrifugal inlet 1201, the solid outlet 1202 is communicated with the outside, the overflow port 1103 is communicated with the mother liquor tank 13, the mother liquor outlet 1203 is communicated with the input end of the mother liquor pump 14, and the output end of the mother liquor pump 14 is communicated with the material inlet 201 and the outside.

[0047] Under the action of the discharge pump 20, the thick crystal slurry enters the head tank 11 through the crystal slurry inlet 1101, and is deposited in the head tank 11 to stay for a period of time for preliminary solid-liquid separation, and under the action of gravity, the crystal particles carrying part of the mother liquor gradually sink, are discharged through the crystal slurry outlet 1102, enter the centrifuge 12 through the centrifugal inlet 1201, and the crystal particles and a small amount of solution in the centrifuge 12 rotate at high speed to generate centrifugal force, the crystal particles are thrown to the inner wall of the centrifuge 12, and the liquid is discharged through the mother liquor outlet 1203 after passing through the filter screen of the centrifuge 12, enters the mother liquor tank 13, and the accumulated crystal particles are discharged from the system through the solid outlet 1202; in addition, the clear liquid in the upper part of the head tank 11 is discharged through the overflow port 1103 and enters the mother liquor tank 13, and the mother liquor is pumped out of the mother liquor tank 13 by the mother liquor pump 14 and is divided into two paths, one of which returns to the evaporation separator 3 for continuous evaporation and concentration treatment to improve the recovery rate of the solute, and the other part of the mother liquor is discharged from the system to prevent the enrichment of organic matter and the accumulation of impurities in the evaporation separator 3, which affects the normal operation of the evaporation separator 3.

[0048] Further improvement is that one of the output ends of the condensate pump 7 is communicated with five branch pipes 15, the five branch pipes 15 are respectively communicated between the output end of the discharge pump 20 and the crystal slurry inlet 1101, between the crystal slurry outlet 1102 and the centrifugal inlet 1201, between the overflow port 1103 and the mother liquor tank 13, between the input end of the mother liquor pump 14 and the mother liquor tank 13, and between the output end of the mother liquor pump 14 and the outside, and each of the branch pipes 15 is provided with a cleaning valve 1501.

[0049] The cleaning valve 1501 corresponding to the five branch pipes 15 is opened, and the condensate water in the condensate tank 6 is extracted by the condensate pump 7, so that the condensate water can be transported between the crystal slurry outlet 1102 and the centrifugal inlet 1201, between the overflow port 1103 and the mother liquor tank 13, between the input end of the mother liquor pump 14 and the mother liquor tank 13, and the output end of the mother liquor pump 14. During the flow of the condensate water, the inner walls of the pipelines are washed and cleaned, and the impurities such as crystals and crystalline substances attached to the inner walls are removed, so that the pipelines are cleaned, the material liquid can smoothly pass through, the evaporation and concentration are smoothly carried out, and the phenomenon of pipe blockage is avoided.

[0050] Further improvement is that the condensing assembly further comprises a condensate preheater 16, the condensate preheater 16 has a condensing inlet 1601, a condensing outlet 1602, a preheating inlet 1603 and a preheating outlet 1604, the condensing inlet 1601 is communicated with another output end of the condensate pump 7, the condensing outlet 1602 is used for communicating with the outside, and the output end of the feeding pump 1 is communicated with the material inlet 201 through the preheating inlet 1603 and the preheating outlet 1604 in sequence.

[0051] After the above structure is adopted, the condensate water in the condensate preheater 16 exchanges heat with the material liquid, so that the material liquid can be preheated, the temperature rise of the material liquid is accelerated, and the concentration crystallization efficiency is improved.

[0052] Further improvement is that the feeding pump 1 has two output ends and is connected with switching valves 101, one of the two output ends of the feeding pump 1 is communicated with the preheating inlet 1603, and the other is communicated with the material inlet 201.

[0053] The feeding pump 1 is provided with two output ends, one of which is directly connected with the heater 2, and the other is connected with the heater 2 through the condensate preheater 16. By adopting the structure, it is convenient to select any one of the output ends in the production process, open the corresponding switching valve 101, and pass the material liquid, and close the other corresponding switching valve 101, so as to facilitate maintenance. In this way, the material conveying and maintenance at the feeding pump 1 can be carried out synchronously and without interference, so as to improve the production efficiency.

[0054] Further improvement is that the condensate tank 6 is connected with a spray water cooler 18 through the spray pump 17, specifically, the spray water cooler 18 has a spray inlet 1801, a spray outlet 1802, a circulating inlet 1803 and a circulating outlet 1804, the circulating inlet 1803 and the circulating outlet 1804 are respectively used for entering and discharging cooling water, the spray inlet 1801 is communicated with the output end of the spray pump 17, and the spray outlet 1802 is communicated with the outside, so that the condensate water in the condensate tank 6 can be entered into the spray water cooler 18 through the spray pump 17, and the condensate water is discharged from the system after heat exchange with the cooling water.

[0055] Further improvement is that the compressor 5 is further provided with a spray water inlet 503 and a drain outlet 504, the spray water inlet 503 is communicated with the output end of the spray pump 17, and the drain outlet 504 is communicated with the condensate tank 6, so that the condensate water can be entered into the spray water inlet 503 through the spray pump 17 to heat absorption and cooling of the compressor 5, and after ensuring the normal and stable operation of the compressor 5, the condensate water is discharged from the drain outlet 504 and returned to the condensate tank 6, thereby saving the amount of cooling water.

[0056] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the technical principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A forced circulation MVR evaporative crystallizer characterized in that, The application relates to a system for producing pure steam, comprising: a feed pump (1); a circulating separation assembly, which comprises a heater (2), a separation unit, a circulating pump (19) and a discharge pump (20), the heater (2) has a material inlet (201), a material outlet (202), a heating steam inlet (203) and a condensate outlet (204), the separation unit has a separation inlet (301), a concentrated liquid outlet (302) and a pure steam outlet (401), the heating steam inlet (203) is used for connecting a live steam source, the input end of the feed pump (1) is communicated with the material inlet (201), the material outlet (202) is communicated with the separation inlet (301), the concentrated liquid outlet (302) is communicated with the material inlet (201) through the circulating pump (19), and the concentrated liquid outlet (302) is communicated with the input end of the discharge pump (20); a solid-liquid separation assembly, which is used for carrying out solid-liquid separation on the material discharged by the discharge pump (20), discharging separated solid out of the system, discharging part of mother liquor out of the system and returning another part of the mother liquor to the circulating separation assembly; a compressor (5), which has a compressed steam inlet (501) communicated with the pure steam outlet (401) and a compressed steam outlet (502) communicated with the heating steam inlet (203); a condensing assembly, which comprises a condensate tank (6) and a condensate pump (7), the condensate tank (6) is communicated between the condensate outlet (204) and the input end of the condensate pump (7), the condensate pump (7) has two output ends, one of which is communicated with the outside world, and the other is connected with the solid-liquid separation assembly and the circulating separation assembly, and both the output ends are connected with switch valves (701); a negative pressure assembly, which comprises a vacuum pump (8), the input end of the vacuum pump (8) is communicated with the condensate tank (6), and the output end is communicated with the outside world.

2. The forced circulation MVR evaporative crystallizer of claim 1, wherein: The negative pressure assembly further comprises a non-condensable gas separator (9), which has a mixing inlet (901), a liquid discharge port (902) and an exhaust port (903), the mixing inlet (901) is communicated with the condensate tank (6), the liquid discharge port (902) is communicated with the input end of the condensate pump (7), and the exhaust port (903) is communicated with the input end of the vacuum pump (8).

3. The forced circulation MVR evaporative crystallizer of claim 2, wherein: The heater (2) has a mixing outlet (205), which is communicated with the mixing inlet (901).

4. The forced circulation MVR evaporative crystallizer of claim 3, wherein: The non-condensable gas separator (9) and the heater (2) are further provided with a non-condensable gas cooler (10), the non-condensable gas cooler (10) has a cooling inlet (1001), a cooling outlet (1002), a cooling inlet (1003) and a cooling outlet (1004), the cooling inlet (1001) and the cooling outlet (1002) are used for entering and discharging cooling water respectively, the mixing outlet (205), the cooling inlet (1003), the cooling outlet (1004) and the mixing inlet (901) are communicated in sequence.

5. The forced circulation MVR evaporative crystallizer of claim 1, wherein: The separation unit includes an evaporation separator (3) and a secondary separator (4), the separation inlet (301) and the concentrated liquid outlet (302) are arranged on the evaporation separator (3), the pure steam outlet (401) is arranged on the secondary separator (4), the evaporation separator (3) is further provided with a secondary steam outlet (303) and a reflux inlet (304), the secondary separator (4) is further provided with a secondary steam inlet (402) and a reflux outlet (403), the reflux outlet (403) is communicated with the reflux inlet (304), and the secondary steam inlet (402) is communicated with the secondary steam outlet (303).

6. The forced circulation MVR evaporative crystallizer of claim 5, wherein: The solid-liquid separation assembly includes a high tank (11), a centrifuge (12), a mother liquor tank (13) and a mother liquor pump (14), the high tank (11) has a crystal slurry inlet (1101), a crystal slurry outlet (1102) and an overflow port (1103), the centrifuge (12) has a centrifugal inlet (1201), a solid outlet (1202) and a mother liquor outlet (1203), the output end of the discharge pump (20) is communicated with the crystal slurry inlet (1101), the crystal slurry outlet (1102) is communicated with the centrifugal inlet (1201), the solid outlet (1202) is communicated with the outside, the overflow port (1103) is communicated with the mother liquor tank (13), the mother liquor outlet (1203) is communicated with the input end of the mother liquor pump (14), the output end of the mother liquor pump (14) is communicated with the material inlet (201), and the output end of the mother liquor pump (14) is further communicated with the outside.

7. The forced circulation MVR evaporative crystallizer of claim 6, wherein: One of the output ends of the condensate pump (7) is communicated with five branch pipes (15), the five branch pipes (15) are respectively communicated between the output end of the discharge pump (20) and the crystal slurry inlet (1101), between the crystal slurry outlet (1102) and the centrifugal inlet (1201), between the overflow port (1103) and the mother liquor tank (13), between the input end of the mother liquor pump (14) and the mother liquor tank (13), and between the output end of the mother liquor pump (14) and the outside, and each branch pipe (15) is provided with a cleaning valve (1501).

8. The forced circulation MVR evaporative crystallizer of claim 1, wherein: The condensing assembly further comprises a condensate water preheater (16) having a condensing inlet (1601), a condensing outlet (1602), a preheating inlet (1603) and a preheating outlet (1604), the condensing inlet (1601) being communicated with the other output end of the condensate water pump (7), the condensing outlet (1602) being used for communicating with the outside, the output end of the feed pump (1) being communicated with the material inlet (201) through the preheating inlet (1603) and the preheating outlet (1604) in sequence.

9. The forced circulation MVR evaporative crystallizer of claim 8, wherein: The feed pump (1) has two output ends and is connected with switching valves (101), one of the two output ends of the feed pump (1) being communicated with the preheating inlet (1603) and the other being communicated with the material inlet (201).

10. The forced circulation MVR evaporative crystallizer of claim 1, wherein: The compressor (5) is a single-screw compressor (5).

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