Anti-scaling method and device for long-period operation of MVR (mechanical vapor recompression) evaporator for concentrating high-carbonate lithium solution

Abstract

The invention discloses an anti-scaling method and device for long-period operation of an MVR (mechanical vapor recompression) evaporator for concentrating a high-carbonate lithium solution, and belongs to the technical field of lithium salt production equipment. The long-period operation anti-scaling method of the MVR evaporator for concentrating the high-carbonate lithium solution comprises the following steps: S1, adding a high-concentration carbonate mother solution into a reaction kettle, and introducing CO2 gas to adjust the pH value of the high-concentration carbonate mother solution; s2, enabling the neutralized high-concentration carbonate mother liquor to flow into a filtering tank, and filtering unconverted CaCO3 microcrystals and colloidal particles by using a ceramic membrane; s3, adding a scale inhibitor into the filtered high-concentration carbonate mother liquor, and fully stirring; according to the method, the COgas is introduced into the high-concentration carbonate mother liquor, so that the COgas is acidified and converted into CO3 < 2-> into HCO3 <->, unconverted CaCO3 microcrystals and colloidal particles are intercepted under the action of the ceramic membrane, crystallization is inhibited in combination with the compound scale inhibitor, and scaling is reduced from the source; non-stop in-situ cleaning is achieved through ultrasonic waves and microbubbles, and production interruption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium salt production equipment, and in particular to a long-cycle anti-scaling method and device for an MVR evaporator used for concentrating a high-carbonate lithium liquid. Background Art

[0002] In the lithium carbonate concentration process, the MVR evaporator feed liquid usually contains a high concentration of carbonate (such as the mother liquor from the carbonization reaction), which leads to the following problems: Scaling mechanism: CO3 at high temperature 2- With Li + , Ca 2+ The combination generates insoluble substances such as Li2CO3 and CaCO3, which rapidly crystallize on the evaporator heating tube wall and separator to form a dense scar layer; Decreased operating efficiency: Scaling leads to a decrease in heat transfer coefficient (20%-40% decrease within 24 hours), reduced evaporation capacity, and forced frequent shutdowns for cleaning (usually every 72-96 hours); High cleaning cost: Traditional pickling (hydrochloric acid / nitric acid) produces lithium-containing waste liquid, resulting in resource waste and environmental pressure.

[0003] Existing technologies typically add scale inhibitors to reduce scaling, but these have drawbacks such as poor adaptability and an inability to remove hard scale online. Therefore, the present invention proposes a method and device for long-term anti-scaling of MVR evaporators that controls crystallization at the source, delays scaling formation, and enables in-situ cleaning. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems in the prior art and to propose a long-cycle anti-scaling method and device for an MVR evaporator used for concentrating high-carbonate lithium liquid.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preventing scaling during long-cycle operation of an MVR evaporator for concentrating a high-carbonate lithium solution comprises the following steps: S1, adding a high-concentration carbonate mother liquor into a reactor, and introducing CO2 gas to adjust the pH value of the high-concentration carbonate mother liquor; S2, the neutralized high concentration carbonate mother liquor flows into the filter tank, and the unconverted C a Filtering of CO3 microcrystals and colloidal particles; S3. Add scale inhibitor to the filtered high-concentration carbonate mother liquor and stir thoroughly; S4, passing the high-concentration carbonate mother liquor into the MVR evaporator for evaporation and using a separator for gas-liquid separation; S5. Detect the scale thickness in the heating tube and the separator through the pressure difference sensor. When it exceeds the preset value, the ultrasonic transducer and the rotary nozzle are activated to clean the heating tube and the separator respectively.

[0006] In some embodiments, the flow rate of CO2 gas introduced into S1 is 0.8-1.2m 3 / h.

[0007] In some embodiments, the operating frequency of the ultrasonic transducer in S4 is 28-40kHz, and the power density is 50-100W / m 2 The pressure of the high-pressure microbubble water ejected by the rotating nozzle is 0.8-1.2MPa, and the bubble diameter is ≤50μm.

[0008] The present invention also provides a long-cycle anti-scaling device for an MVR evaporator for concentrating a high-concentration lithium carbonate solution, comprising a reactor for reacting a high-concentration carbonate mother liquor with CO2 gas and a filter tank for filtering the high-concentration carbonate mother liquor, wherein a drain port at the bottom of the filter tank is connected to an evaporation chamber of the evaporator via a connecting pipe, and the evaporation chamber is connected to a separator. The bottom of the filter tank is provided with an addition port for adding antiscalant and a stirring blade for stirring; A plurality of heating tubes are provided in the evaporation chamber, and a plurality of ultrasonic transducers are respectively installed on the surfaces of the plurality of heating tubes. A rotating nozzle for spraying high-pressure microbubble water is installed at the bottom of the separator.

[0009] In some embodiments, a filter membrane is fixed inside the filter tank, and a backwash component for backwashing the filter membrane is provided inside the filter tank. The filter membrane is a double-layer ceramic membrane, and the filter membrane is in an upwardly protruding arc shape.

[0010] In some embodiments, the backflush assembly includes a collecting hopper fixed on the inner wall of the filter tank for collecting the high-concentration carbonate mother liquor after filtration, and a first water pump fixed on the surface of the filter tank. The first water pump is used to transport the high-concentration carbonate mother liquor in the collecting hopper to the interior of the filter membrane. A baffle is provided under the collecting hopper for closing the bottom of the collecting hopper.

[0011] In some embodiments, the inner wall of the filter tank is provided with a cleaning assembly for cleaning impurities accumulated on the outer ring of the filter membrane. The cleaning assembly includes an outer toothed ring rotating on the inner wall of the filter tank and a scraper fixed on the inner side of the outer toothed ring, and the scraper contacts the surface of the filter membrane.

[0012] In some embodiments, a guide tube for discharging impurities is fixed on the surface of the filter tank, the upper inlet of the guide tube is connected to the filter tank, and the upper inlet of the guide tube is in contact with the upper surface of the filter membrane. The guide tube inlet is hinged with a cover plate for closing the guide tube, and a spring is provided on the side of the cover plate facing the inside of the guide tube for pushing the cover plate to close the guide tube.

[0013] In some embodiments, the cover plate opens the closure of the guide tube through a pushing assembly, and the pushing assembly includes a push rod hinged on the inner wall of the filter tank and a push plate for pushing the push rod to rotate. The lower end of the push rod abuts against the surface of the cover plate, and the upper end of the push rod cooperates with the push plate. Both ends of the push plate are provided with arc surfaces for pushing the push rod.

[0014] In some embodiments, a retaining ring for shielding the outer gear ring and the scraper is fixed to the inner wall of the filter tank, and the retaining ring is located above the outer gear ring.

[0015] Compared with the prior art, the present invention provides a method and device for anti-scaling of an MVR evaporator for concentrating a high-carbonate lithium solution during long-cycle operation, which has the following beneficial effects.

[0016] 1. The present invention, by introducing CO2 gas into high concentration carbonate mother liquor, makes CO2 gas acidify and convert into CO3 2- HCO3 - Under the action of ceramic membrane, the unconverted C a The retention of CO3 microcrystals and colloidal particles, combined with compound antiscalants, inhibits crystallization and reduces scaling formation from the root; ultrasonic waves and microbubbles achieve non-stop in-situ cleaning, reducing production interruptions.

[0017] 2. The present invention sets a backflush component in the filter tank to backwash the filter membrane, which does not affect the filtering function of the filter membrane and avoids the need to stop the filter to clean the filter membrane due to saturation of the filter membrane. By setting a cleaning component, impurities accumulated on the surface of the filter membrane are cleaned.

[0018] Other advantages, objects and features of the present invention will be described in part in the following description; and in part will be apparent to those skilled in the art based on an examination of the following; or may be taught from the practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the workflow of the present invention.

[0020] Figure 2 It is a schematic diagram of the positive axial structure of the device of the present invention.

[0021] Figure 3It is a schematic diagram of the cross-sectional structure of the evaporation chamber and separator in the present invention.

[0022] Figure 4 It is a schematic diagram of the rear axial structure of the device of the present invention.

[0023] Figure 5 It is a schematic side sectional structural diagram of the filter tank in the present invention.

[0024] Figure 6 It is a schematic diagram of the cross-sectional structure of the filter tank in the present invention when viewed from above.

[0025] Figure 7 It is a schematic diagram of the partial structure of the cleaning component in the present invention.

[0026] Figure 8 It is a schematic diagram of the rear cross-sectional structure of the filter tank in the present invention.

[0027] Figure 9 For the present invention Figure 8 Schematic diagram of the structure enlarged at point A.

[0028] In the picture: 1. Reactor; 2. Filter tank; 201; Filter membrane; 202. Stirring blade; 203. Adding port; 204. Backflush assembly; 2041. Collecting bucket; 2042. First water pump; 2043. Baffle; 3. Evaporator; 301. Evaporation chamber; 3011. Heating tube; 302. Separator; 4. Cleaning assembly; 401. Outer gear ring; 402. Scraper; 403. Gear; 4031. Shell; 404. Draft tube; 4041. Cover plate; 4042. Spring; 405. Collecting box; 406. Top pressure assembly; 4061. Push rod; 4062. Push plate; 5. Retaining ring; 6. Ultrasonic transducer; 7. Rotating nozzle. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0030] Reference Figure 1-9 A method for preventing scaling of an MVR evaporator for long-term operation for concentrating high-carbonate lithium liquid comprises the following steps: S1, add high concentration carbonate mother liquor into reactor 1, and introduce CO2 gas to adjust the pH value of high concentration carbonate mother liquor; the introduction flow rate is 0.8-1.2m 3 / h, and use a pH sensor to detect the pH value of the high-concentration carbonate mother liquor and accurately control the pH to within the range of 6-7; S2, make the high concentration carbonate mother liquor after neutralization flow into filter tank 2, use ceramic membrane to remove unconverted Ca CO3 microcrystals and colloidal particles are filtered, and the pore size of the ceramic membrane is 0.04-0.06μm; S3. Add scale inhibitor to the filtered high-concentration carbonate mother liquor and stir thoroughly; S4, the high-concentration carbonate mother liquor is passed into the MVR evaporator 3, evaporated at 88-92°C and a vacuum degree of -90 to -95 kPa, and the gas-liquid separation is performed using the separator 302; S5. Use the pressure difference sensor to detect the scale thickness in the heating tube 3011 and the separator 302. When the scale thickness exceeds the preset value, the ultrasonic transducer 6 and the rotary nozzle 7 are activated to clean the heating tube 3011 and the separator 302 respectively. The operating frequency of the ultrasonic transducer 6 is 28-40kHz, and the power density is 50-100W / m 2 , periodically emitting ultrasonic waves; the high-pressure micro-bubble water pressure ejected by the rotating nozzle 7 is 0.8-1.2MPa, and the bubble diameter is ≤50μm.

[0031] It is understood that after CO2 gas is introduced into the high concentration carbonate mother liquor, free CO3 2- Converted to HCO3 - (Reaction formula: CO3 2- +CO2+H2O→2HCO3 - ), reduce the crystallization tendency, under the action of ceramic membrane, the unconverted C a CO3 microcrystals and colloidal particles are retained; after the high concentration carbonate mother liquor is PH neutralized and filtered, CO3 in the high concentration carbonate mother liquor is 2- The concentration dropped from the initial 8000ppm to below 2000ppm; After adding the scale inhibitor, the scaling rate is reduced to ≤0.1mm / 24h, and the scale inhibition rate is ≥85%. The scale thickness is monitored in real time by the pressure difference sensor. When the heat transfer coefficient drops by ≥15%, the ultrasonic transducer 6 and the rotating nozzle 7 are triggered to work and realize in-situ cleaning.

[0032] Specifically, the scale inhibitor comprises 36%-41% ATMP, 6%-22% PESA, and the balance sodium citrate in a weight ratio, and the addition ratio of the scale inhibitor is 0.1% of the high-concentration carbonate mother liquor.

[0033] It is understandable that when the scale inhibitor is mixed with high-concentration carbonate mother liquor, ATMP chelates Ca 2+ Mg 2+ , inhibiting C a CO3 crystal nuclei are generated; PESA disperses Li2CO3 microcrystals to prevent them from agglomerating and adhering; sodium citrate maintains the system pH at 7.0-7.5 to avoid HCO3 - Reverse conversion to CO3 2- .

[0034] The present invention also provides a long-cycle anti-scaling device for an MVR evaporator for concentrating a high-concentration lithium carbonate solution, comprising a reactor 1 for reacting a high-concentration carbonate mother liquor with CO2 gas, and a filter tank 2 for filtering the high-concentration carbonate mother liquor. The reactor 1 is prior art and will not be described in detail. The discharge port of the reactor 1 is connected to the liquid inlet of the filter tank 2 via a connecting pipe. A pH sensor is provided inside the reactor 1, and a water pump is provided on the surface of the connecting pipe. The discharge port at the bottom of the filter tank 2 is connected to an evaporation chamber 301 of an evaporator 3 via a connecting pipe. A water pump is provided on the surface of the connecting pipe. The evaporation chamber 301 is connected to a separator 302. The bottom of the filter tank 2 is provided with an addition port 203 for adding scale inhibitors and a stirring blade 202 for stirring. The stirring blade 202 rotates at the bottom of the filter tank 2. The stirring blade 202 is driven to rotate by a drive motor fixed to the lower surface of the filter tank 2. A plurality of heating tubes 3011 are provided in the evaporation chamber 301, and a plurality of ultrasonic transducers 6 are respectively installed on the surfaces of the plurality of heating tubes 3011. A differential pressure sensor for detecting the thickness of scale is provided inside the evaporation chamber 301. A rotating nozzle 7 for spraying high-pressure microbubble water is installed at the bottom of the separator 302. The lower end of the rotating nozzle 7 is connected to a Venturi tube, and the other end of the Venturi tube is connected to a water pump. A differential pressure sensor for detecting the thickness of scale is provided inside the separator 302.

[0035] It can be understood that by adding a high-concentration carbonate mother liquor into the reactor 1 and introducing CO2 gas to react with the high-concentration carbonate mother liquor, the pH value of the high-concentration carbonate mother liquor is detected by a pH sensor. When the pH value of the high-concentration carbonate mother liquor reaches a corresponding range, the water pump is used to pump the high-concentration carbonate mother liquor in the reactor 1 into the filter tank 2 for filtration. The filtered high-concentration carbonate mother liquor flows down to the bottom of the filter tank 2, and a scale inhibitor is added through the addition port 203. The driving motor drives the stirring blade 202 to stir. After mixing, the mixture enters the evaporation chamber 301, is evaporated by the heating tube 3011, and is separated into steam and water under the action of the separator 302. When the heating tube 3011 and the separator 302 need to be cleaned, the ultrasonic transducer 6 generates ultrasonic waves to clean the heating tube 3011, and the water is pumped through the venturi tube into the rotary nozzle 7, so that the rotary nozzle 7 sprays high-pressure microbubble water to clean the separator 302.

[0036] Specifically, a filter membrane 201 is fixed inside the filter tank 2, and a backwash component 204 for backwashing the filter membrane 201 is provided inside the filter tank 2. The filter membrane 201 adopts a double-layer ceramic membrane, and the filter membrane 201 is an upwardly protruding arc. The backflush assembly 204 includes a collecting hopper 2041 fixed on the inner wall of the filter tank 2 for collecting the filtered high-concentration carbonate mother liquor and a first water pump 2042 fixed on the surface of the filter tank 2. The collecting hopper 2041 is located below the filter membrane 201. The water inlet of the first water pump 2042 is connected to the bottom of the collecting hopper 2041 through a hose, and the water outlet of the first water pump 2042 is connected to the filter membrane 201. The collecting hopper 2041 is funnel-shaped, and the bottom of the collecting hopper 2041 is open. A baffle 2043 for closing the bottom of the collecting hopper 2041 is provided below the collecting hopper 2041. The baffle 2043 rotates on the lower surface of the collecting hopper 2041. The baffle 2043 is driven to rotate by an electric push rod 4061. The two ends of the electric push rod 4061 are respectively hinged on the surface of the baffle 2043 and the inner wall of the filter tank 2.

[0037] It can be understood that by using the filter membrane 201, the high-concentration carbonate mother liquor is filtered, and by providing the backwash component 204, the filter membrane 201 is backwashed, thereby preventing the filter membrane 201 from being blocked during long-term use, requiring shutdown for cleaning and affecting the evaporation efficiency. When the filter membrane 201 needs to be cleaned, the electric push rod 4061 drives the baffle 2043 to rotate, thereby blocking the bottom of the collection hopper 2041, so that the collection hopper 2041 collects the filtered high-concentration carbonate mother liquor, and the first water pump 2042 is operated to extract the high-concentration carbonate mother liquor collected in the collection hopper 2041 and pressurize it and inject it between the filter membranes 201, thereby backwashing the filter membrane 201. Since the filter membrane 201 is an upwardly protruding arc, the impurities backwashed slide to the outer ring of the filter membrane 201 and temporarily accumulate, without affecting the filtering function of the filter membrane 201. Specifically, the inner wall of the filter tank 2 is provided with a cleaning assembly 4 for cleaning impurities accumulated on the outer ring of the filter membrane 201. The cleaning assembly 4 includes an outer gear ring 401 rotating on the inner wall of the filter tank 2 and a scraper 402 fixed on the inner side of the outer gear ring 401. The outer gear ring 401 rotates on the inner wall of the filter tank 2 through an annular slide rail. The outer gear ring 401 is located above the filter tank 2. The scraper 402 contacts the surface of the filter membrane 201. A gear 403 is meshed with the surface of the outer gear ring 401. The gear 403 rotates inside the housing 4031. The housing 4031 is fixed on the surface of the filter tank 2 and is connected to the filter tank 2. A drive motor is fixed on the upper surface of the housing 4031, and the drive motor drives the gear 403 to rotate. A guide tube 404 for discharging impurities is fixed on the surface of the filter tank 2. A collection box 405 is provided at the outlet position of the lower end of the guide tube 404. The collection box 405 is placed on the surface of a placement plate, and the placement plate is fixed to the surface of the filter tank 2. The inlet of the upper end of the guide tube 404 is connected to the filter tank 2, and the inlet of the upper end of the guide tube 404 is in contact with the upper surface of the filter membrane 201. The inlet of the guide tube 404 is hinged with a cover plate 4041 for closing the guide tube 404. A spring 4042 is fixed on the side of the cover plate 4041 facing the inside of the guide tube 404, and the other end of the spring 4042 is fixed to the inner wall of the guide tube 404. The cover plate 4041 opens the seal on the guide tube 404 through the pressing assembly 406. The pressing assembly 406 includes a push rod 4061 hinged on the inner wall of the filter tank 2 and a push plate 4062 for pushing the push rod 4061 to rotate. The push rod 4061 is located between the outer gear ring 401 and the filter membrane 201. The lower end of the push rod 4061 abuts against the surface of the cover plate 4041, and the upper end of the push rod 4061 cooperates with the push plate 4062. Both ends of the push plate 4062 are provided with arc surfaces for pushing the push rod 4061. The position of the push plate 4062 corresponds to that of the scraper 402, and the surface of the scraper 402 is provided with a notch for avoiding the push rod 4061.

[0038] It is understood that when it is necessary to clean the impurities on the outer ring of the filter membrane 201, the driving motor drives the gear 403 to rotate, so that the outer gear ring 401 drives the scraper 402 to rotate on the outer ring of the filter membrane 201, thereby pushing the impurities to move in the direction of the guide tube 404. When the outer gear ring 401 drives the push plate 4062 to contact the upper end of the push rod 4061, the push rod 4061 rotates, so that the push rod 4061 pushes the cover plate 4041 to rotate, so that the guide tube 404 moves. The tube 404 is connected to the filter tank 2, and the impurities pushed by the scraper 402 are discharged into the collection box 405 through the guide tube 404. When the scraper 402 passes over the guide tube 404, the push plate 4062 is separated from the push rod 4061, and the cover plate 4041 is pushed by the spring 4042 to close the guide tube 404, preventing the high-concentration carbonate mother liquor from flowing out of the filter tank 2 through the guide tube 404 when filtering, thereby achieving the cleaning of the filter membrane 201 without stopping the machine.

[0039] Specifically, a retaining ring 5 for shielding the outer gear ring 401 and the scraper 402 is fixed to the inner wall of the filter tank 2 . The retaining ring 5 is located above the outer gear ring 401 and is funnel-shaped.

[0040] It is understandable that by providing the retaining ring 5 , the outer gear ring 401 and the scraper 402 are shielded to prevent high-concentration carbonate mother liquor from directly flowing onto the surface of the outer gear ring 401 , causing impurities to accumulate and affect the rotation of the outer gear ring 401 .

[0041] Example 1: This embodiment provides a method for preventing scaling during long-term operation of an MVR evaporator for concentrating a high-carbonate lithium solution. Unlike the above embodiment, the method includes the following steps: S1, add high concentration carbonate mother liquor into reactor 1, and introduce CO2 gas to adjust the pH value of high concentration carbonate mother liquor; the introduction flow rate is 0.8m 3 / h, and a pH sensor is used to detect the pH value of the high-concentration carbonate mother liquor and accurately control the pH to 6.8; S2, make the high concentration carbonate mother liquor after neutralization flow into filter tank 2, use ceramic membrane to remove unconverted C a CO3 microcrystals and colloidal particles are filtered, and the pore size of the ceramic membrane is 0.05μm; S3. Add scale inhibitor to the filtered high-concentration carbonate mother liquor and stir thoroughly; S4, the high-concentration carbonate mother liquor is passed into the MVR evaporator 3, evaporated at 92°C and vacuum degree -95kPa, and the gas-liquid separation is performed using the separator 302; S5. Detect the scale thickness in the heating tube 3011 and the separator 302 through the sensor. When the scale thickness exceeds the preset value, the ultrasonic transducer 6 and the rotary nozzle 7 are activated to clean the heating tube 3011 and the separator 302 respectively. The operating frequency of the ultrasonic transducer 6 is 35kHz, and the power density is 80W / m 2 , periodically emitting ultrasonic waves; the high-pressure microbubble water pressure ejected by the rotating nozzle 7 is 1MPa, and the bubble diameter is ≤50μm.

[0042] Specifically, the scale inhibitor includes 38% ATMP, 15% PESA, and the balance sodium citrate in a weight ratio, and the addition ratio of the scale inhibitor is 0.1% of the high-concentration carbonate mother liquor.

[0043] Example 2: This embodiment provides a method for preventing scaling during long-term operation of an MVR evaporator for concentrating a high-carbonate lithium solution. Unlike the above embodiment, the method includes the following steps: S1, add high concentration carbonate mother liquor into reactor 1, and introduce CO2 gas to adjust the pH value of high concentration carbonate mother liquor; the introduction flow rate is 1m 3 / h, and use a pH sensor to detect the pH value of the high-concentration carbonate mother liquor and accurately control the pH to 6; S2, make the high concentration carbonate mother liquor after neutralization flow into filter tank 2, use ceramic membrane to remove unconverted C a CO3 microcrystals and colloidal particles are filtered, and the pore size of the ceramic membrane is 0.04μm; S3. Add scale inhibitor to the filtered high-concentration carbonate mother liquor and stir thoroughly; S4, the high-concentration carbonate mother liquor is passed into the MVR evaporator 3, evaporated at 88°C and a vacuum degree of 90 kPa, and the gas-liquid separation is performed using the separator 302; S5. Detect the scale thickness in the heating tube 3011 and the separator 302 through the sensor. When the scale thickness exceeds the preset value, the ultrasonic transducer 6 and the rotary nozzle 7 are activated to clean the heating tube 3011 and the separator 302 respectively. The operating frequency of the ultrasonic transducer 6 is 40kHz and the power density is 100W / m 2 , periodically emitting ultrasonic waves; the high-pressure microbubble water pressure ejected by the rotating nozzle 7 is 1.2MPa, and the bubble diameter is ≤50μm.

[0044] Specifically, the scale inhibitor includes ATMP 41%, PESA 6%, and the balance sodium citrate in a weight ratio, and the addition ratio of the scale inhibitor is 0.1% of the high-concentration carbonate mother liquor.

[0045] Example 3: This embodiment provides a method for preventing scaling during long-term operation of an MVR evaporator for concentrating a high-carbonate lithium solution. Unlike the above embodiment, the method includes the following steps: S1, add high concentration carbonate mother liquor into reactor 1, and introduce CO2 gas to adjust the pH value of high concentration carbonate mother liquor; the introduction flow rate is 0.8m 3 / h, and use a pH sensor to detect the pH value of the high-concentration carbonate mother liquor and accurately control the pH to 7; S2, make the high concentration carbonate mother liquor after neutralization flow into filter tank 2, use ceramic membrane to remove unconverted C a CO3 microcrystals and colloidal particles are filtered, and the pore size of the ceramic membrane is 0.06μm; S3. Add scale inhibitor to the filtered high-concentration carbonate mother liquor and stir thoroughly; S4, the high-concentration carbonate mother liquor is passed into the MVR evaporator 3, evaporated at 92°C and a vacuum degree of 93 kPa, and the gas-liquid separation is performed using the separator 302; S5. Detect the scale thickness in the heating tube 3011 and the separator 302 through the sensor. When the scale thickness exceeds the preset value, the ultrasonic transducer 6 and the rotary nozzle 7 are activated to clean the heating tube 3011 and the separator 302 respectively. The operating frequency of the ultrasonic transducer 6 is 28kHz, and the power density is 50W / m 2 , periodically emitting ultrasonic waves; the high-pressure microbubble water pressure ejected by the rotating nozzle 7 is 0.8MPa, and the bubble diameter is ≤50μm.

[0046] Specifically, the scale inhibitor includes 36% ATMP, 22% PESA, and the balance sodium citrate in a weight ratio, and the addition ratio of the scale inhibitor is 0.1% of the high-concentration carbonate mother liquor.

[0047] The comparison results of multiple embodiments are shown in the following table: <![CDATA[CO3 in the high-concentration carbonate mother liquor 2- concentration]]> <![CDATA[Supersaturation of Li2CO3]]> Scaling rate Residual scale thickness after 380 hours of continuous operation Example 1 1000ppm 15g / l 0.1mm / 24h 0.3mm Example 2 1800ppm 17g / l 0.3mm / 24h 0.5mm Example 3 1300ppm 18g / l 0.4mm / 24h 0.7mm Through comparison, it was found that Example 1 had the best effect. After adding the scale inhibitor, the scaling rate was reduced to 0.1 mm / 24 h. After 380 hours of continuous operation, the residual scaling thickness was 0.3 mm. No shutdown for cleaning was required, which effectively reduced production interruptions.

[0048] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

[0049] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0050] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for preventing scaling during long-term operation of an MVR evaporator for concentrating high-carbonate lithium liquid, characterized in that: The following steps are involved: S1, adding a high-concentration carbonate mother liquor into the reactor (1), and introducing CO2 gas to adjust the pH value of the high-concentration carbonate mother liquor; S2, the neutralized high concentration carbonate mother liquor flows into the filter tank (2), and the unconverted C a Filtering of CO3 microcrystals and colloidal particles; S3. Add scale inhibitor to the filtered high-concentration carbonate mother liquor and stir thoroughly; S4, passing the high-concentration carbonate mother liquor into the MVR evaporator (3) for evaporation and using the separator (302) for gas-liquid separation; S5. Detecting the scale thickness in the heating tube (3011) and the separator (302) through a pressure differential sensor. When the scale thickness exceeds a preset value, the ultrasonic transducer (6) and the rotary nozzle (7) are operated to clean the heating tube (3011) and the separator (302), respectively.

2. The method for preventing scaling of an MVR evaporator for long-term operation for concentrating a high-carbonate lithium solution according to claim 1, characterized in that: The flow rate of CO2 gas introduced into S1 is 0.8-1.2m 3 / h.

3. The method for preventing scaling of an MVR evaporator for long-term operation for concentrating a high-carbonate lithium solution according to claim 1, characterized in that: The operating frequency of the ultrasonic transducer (6) in S4 is 28-40kHz, and the power density is 50-100W / m 2 The high-pressure microbubble water ejected by the rotating nozzle (7) has a pressure of 0.8-1.2 MPa and a bubble diameter of ≤50 μm.

4. A long-cycle anti-scaling device for MVR evaporator for high-carbonate lithium liquid concentration, characterized in that: The invention comprises a reactor (1) for reacting a high-concentration carbonate mother liquor with CO2 gas, and a filter tank (2) for filtering the high-concentration carbonate mother liquor, wherein a drain port at the bottom of the filter tank (2) is connected to an evaporation chamber (301) of an evaporator (3) via a connecting pipe, and a separator (302) is provided in communication with the evaporation chamber (301); The bottom of the filter tank (2) is provided with an addition port (203) for adding a scale inhibitor and a stirring blade (202) for stirring; A plurality of heating tubes (3011) are provided in the evaporation chamber (301), and a plurality of ultrasonic transducers (6) are respectively installed on the surfaces of the plurality of heating tubes (3011). A rotating nozzle (7) for spraying high-pressure microbubble water is installed at the bottom of the separator (302).

5. The long-cycle anti-scaling device for MVR evaporator for concentrating high-carbonate lithium liquid according to claim 4, characterized in that: A filter membrane (201) is fixed inside the filter tank (2), and a backwash component (204) for backwashing the filter membrane (201) is provided inside the filter tank (2). The filter membrane (201) is a double-layer ceramic membrane, and the filter membrane (201) is in an upwardly protruding arc shape.

6. The long-cycle anti-scaling device for MVR evaporator for concentrating high-carbonate lithium liquid according to claim 5, characterized in that: The backflushing assembly (204) comprises a collecting hopper (2041) fixed on the inner wall of the filter tank (2) for collecting the filtered high-concentration carbonate mother liquor, and a first water pump (2042) fixed on the surface of the filter tank (2). The first water pump (2042) is used to transport the high-concentration carbonate mother liquor in the collecting hopper (2041) to the interior of the filter membrane (201). A baffle (2043) is provided below the collecting hopper (2041) for sealing the bottom of the collecting hopper (2041).

7. The long-cycle anti-scaling device for MVR evaporator for concentrating high-carbonate lithium liquid according to claim 5, characterized in that: The inner wall of the filter tank (2) is provided with a cleaning assembly (4) for cleaning impurities accumulated on the outer ring of the filter membrane (201), the cleaning assembly (4) comprising an outer toothed ring (401) rotating on the inner wall of the filter tank (2) and a scraper (402) fixed on the inner side of the outer toothed ring (401), the scraper (402) abutting against the surface of the filter membrane (201).

8. The long-cycle anti-scaling device for MVR evaporator for concentrating high-carbonate lithium liquid according to claim 7, characterized in that: A guide tube (404) for discharging impurities is fixed on the surface of the filter tank (2); an upper inlet of the guide tube (404) is connected to the filter tank (2), and the upper inlet of the guide tube (404) is in contact with the upper surface of the filter membrane (201); a cover plate (4041) for closing the guide tube (404) is hingedly connected to the inlet of the guide tube (404); a spring (4042) for pushing the cover plate (4041) to close the guide tube (404) is provided on a side of the cover plate (4041) facing the interior of the guide tube (404).

9. The long-cycle anti-scaling device for MVR evaporator for concentrating high-carbonate lithium liquid according to claim 8, characterized in that: The cover plate (4041) opens the seal of the guide tube (404) through a pressing assembly (406), and the pressing assembly (406) includes a push rod (4061) hinged on the inner wall of the filter tank (2) and a push plate (4062) for pushing the push rod (4061) to rotate. The lower end of the push rod (4061) contacts the surface of the cover plate (4041), and the upper end of the push rod (4061) cooperates with the push plate (4062). Both ends of the push plate (4062) are provided with arc surfaces for pushing the push rod (4061).

10. The long-cycle operation anti-scaling device for MVR evaporator for concentrating high-carbonate lithium liquid according to claim 7, characterized in that: A retaining ring (5) for shielding the outer toothed ring (401) and the scraper (402) is fixed to the inner wall of the filter tank (2), and the retaining ring (5) is located above the outer toothed ring (401).

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