Evaporation device for byproduct sodium sulfate in lithium carbonate preparation

Abstract

The utility model discloses a kind of evaporation devices for byproduct sodium sulfate in lithium carbonate preparation, belong to sodium sulfate evaporation crystallization technical field, mainly for the processing of byproduct sodium sulfate in lithium carbonate preparation. The technical problem to be solved by the utility model is to provide a kind of evaporation device for byproduct sodium sulfate in lithium carbonate preparation, including MVR evaporation crystallization system, feeding system, steam condensate tank and outer circulation heat exchanger, outer circulation heat exchanger material import is connected with feeding system and is equipped with first temperature sensor, first pressure sensor, its material export is connected with MVR evaporation crystallization system and is equipped with second temperature sensor, second pressure sensor;Its condensate import is connected with steam condensate tank and is equipped with third temperature sensor, its condensate import is connected with outside and is equipped with fourth temperature sensor;The device is based on retaining the original structure of MVR evaporation crystallization system, improve its evaporation capacity, sodium sulfate solution processing capacity and sodium sulfate output.

Description

Technical Field

[0001] This utility model relates to the field of sodium sulfate evaporation and crystallization technology, and in particular to an evaporation device for sodium sulfate, a byproduct of lithium carbonate preparation. Background Technology

[0002] In the post-processing stage of crude lithium carbonate, the wastewater is rich in inorganic salts such as sodium sulfate. These salts are concentrated and crystallized using an MVR (Mechanical Vapor Recompression) evaporation crystallization system to obtain sodium sulfate (sodium sulfate anhydrous), and the mother liquor is returned to the upstream process, achieving resource recycling. Specifically, the MVR evaporation crystallization system 3 includes an evaporator crystallizer 31, which is connected to a circulating pump 32, a heat exchanger 33, and a recompression blower 34. Heat exchange is achieved using the circulating pump 32 in conjunction with the heat exchanger 33, and the recompression blower 34 compresses the internal steam to recover the heat source, thereby treating the sodium sulfate solution. However, the MVR evaporation crystallization system 3 is affected by the MVR evaporator crystallizer 31 itself, which suffers from problems such as fixed evaporation rate, difficulty in increasing processing capacity, and internal scaling, resulting in low sodium sulfate solution treatment efficiency and low sodium sulfate yield.

[0003] To further improve the evaporation capacity of the existing MVR evaporation crystallization system 3, thereby increasing the sodium sulfate solution processing capacity and the production of sodium sulfate, it is urgent to improve the existing MVR evaporation crystallization system 3. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide an evaporation device for sodium sulfate, a by-product in lithium carbonate preparation. It is mainly used for the treatment of sodium sulfate, a by-product in lithium carbonate preparation, so as to improve the evaporation capacity of the existing MVR evaporation system without changing the existing MVR evaporation crystallization system, thereby increasing the amount of sodium sulfate solution processed and increasing the yield of sodium sulfate.

[0005] This utility model discloses an evaporation device for sodium sulfate, a byproduct in lithium carbonate production. It includes an MVR evaporation and crystallization system, a feeding system connected to the inlet of the MVR evaporation and crystallization system, and a steam condensate tank connected to the condensate outlet of the MVR evaporation and crystallization system. It also includes an external circulation heat exchanger disposed between the feeding system and the MVR evaporation and crystallization system. The material inlet of the external circulation heat exchanger is connected to the outlet of the feeding system, and the material outlet of the external circulation heat exchanger is connected to the material inlet of the MVR evaporation and crystallization system. The condensate inlet of the external circulation heat exchanger is connected to the steam condensate tank, and the condensate outlet of the external circulation heat exchanger is connected to the outside environment. The material inlet of the external circulation heat exchanger is equipped with a first temperature sensor and a first pressure sensor, and the material outlet of the external circulation heat exchanger is equipped with a second temperature sensor and a second pressure sensor. The condensate inlet of the external circulation heat exchanger is equipped with a third temperature sensor, and the condensate outlet of the external circulation heat exchanger is equipped with a fourth temperature sensor.

[0006] Furthermore, the feeding system includes a sodium sulfate raw solution tank, the outlet of which is equipped with a feed pump connected to the material inlet of the MVR evaporation crystallization system, and the outlet of the feed pump is equipped with a first discharge pipe connected to the MVR evaporation crystallization system and a second discharge pipe connected to the material inlet pipe of the external circulation heat exchanger.

[0007] As a preferred embodiment, the material inlet pipe is equipped with a material inlet control valve, and the material outlet pipe is equipped with a material outlet control valve; the first discharge pipe is equipped with a material input control valve and a material output control valve, the material input control valve is located at the end of the first discharge pipe near the feed pump, and the material output control valve is located at the end of the first discharge pipe near the MVR evaporation crystallization system.

[0008] Furthermore, the condensate inlet pipe is equipped with a condensate inlet control valve, and the condensate outlet pipe is equipped with a condensate outlet control valve.

[0009] As a preferred embodiment, the condensate inlet pipe is also equipped with a steam condensate pump.

[0010] Furthermore, the material inlet temperature detected by the first temperature sensor is controlled at 50-70℃, and the material outlet temperature detected by the second temperature sensor is controlled at 75-90℃.

[0011] Furthermore, the pressure difference detected between the first pressure sensor and the second pressure sensor is controlled within 0-200 kPa.

[0012] The beneficial effects of this utility model are as follows: The evaporation device for sodium sulfate, a byproduct of lithium carbonate production, preheats the sodium sulfate solution input into the MVR evaporation and crystallization system by adding an external circulation heat exchanger between the feeding system and the MVR evaporation and crystallization system. This reduces the evaporation energy consumption in the MVR evaporation and crystallization system, improves the evaporation efficiency, solves the problem of fixed processing capacity and insufficient evaporation capacity of the MVR evaporation system, and effectively increases the sodium sulfate solution processing capacity and sodium sulfate production. Simultaneously, temperature and pressure sensors are added to the material inlet and outlet of the external circulation heat exchanger to effectively control the material feed temperature, ensuring the sodium sulfate processing capacity, and slowing down the scaling rate of the heat exchanger, thus improving equipment lifespan and reducing maintenance costs. Therefore, the evaporation device for sodium sulfate, a byproduct of lithium carbonate production, achieves a triple improvement in evaporation efficiency, processing capacity, and equipment lifespan by adding an external circulation heat exchanger between the feeding system and the MVR evaporation and crystallization system, combined with the synergistic innovation of temperature and pressure sensors, while retaining the original structure of the MVR evaporation and crystallization system. Attached Figure Description

[0013] Figure 1 : A schematic diagram of the evaporation device for sodium sulfate, a byproduct of lithium carbonate production, provided by this utility model; Reference numerals: 1-Feeding system; 11-Sodium sulfate stock solution tank; 12-Feed pump; 121-First discharge pipe; 1211-Material input control valve; 1212-Material output control valve; 122-Second discharge pipe; 2-External circulation heat exchanger; 21-Material inlet pipe; 211-Material inlet control valve; 22-Material outlet pipe; 221-Material outlet control valve; 23-Condensate inlet pipe; 231-Condensate inlet control valve; 232-Steam condensate pump; 24-Condensate outlet pipe; 241-Condensate outlet control valve; 25-First temperature sensor; 26-Second temperature sensor; 27-First pressure sensor; 28-Second pressure sensor; 29-Third temperature sensor; 210-Fourth temperature sensor; 3-MVR evaporation crystallization system; 31-Evaporator crystallizer; 32-Circulation pump; 33-Heat exchanger; 34-Recompression blower; 4-Steam condensate tank. Detailed Implementation

[0014] The present invention will be further described below.

[0015] This invention provides an evaporation device for sodium sulfate, a byproduct of lithium carbonate production. It is mainly used for processing sodium sulfate, a byproduct of lithium carbonate production. The device includes an MVR evaporation and crystallization system 3, a feeding system 1 connected to the inlet of the MVR evaporation and crystallization system 3, and a steam condensate tank 4 connected to the condensate outlet of the MVR evaporation and crystallization system 3. It also includes an external circulation heat exchanger 2 disposed between the feeding system 1 and the MVR evaporation and crystallization system 3. The material inlet of the external circulation heat exchanger 2 is provided with a material inlet pipe 21 connected to the outlet of the feeding system 1, and the material outlet of the external circulation heat exchanger 2 is connected to the MVR evaporation and crystallization system 3. The external circulation heat exchanger 2 has a material outlet pipe 22 connected to the material inlet; the external circulation heat exchanger 2 has a condensate inlet pipe 23 connected to the steam condensate tank 4, and a condensate outlet pipe 24 connected to the outside; the external circulation heat exchanger 2 has a first temperature sensor 25 and a first pressure sensor 27 at the material inlet, and a second temperature sensor 26 and a second pressure sensor 28 at the material outlet; the external circulation heat exchanger 2 has a third temperature sensor 29 at the condensate inlet, and a fourth temperature sensor 210 at the condensate outlet.

[0016] like Figure 1 As shown, the evaporation device for sodium sulfate, a byproduct of lithium carbonate production, includes an MVR evaporation crystallization system 3, a feed system 1 connected to the inlet of the MVR evaporation crystallization system 3, and a steam condensate tank 4 connected to the condensate outlet of the MVR evaporation crystallization system 3. The MVR evaporation crystallization system 3 adopts an existing structure, including an evaporator, a circulating pump, a heat exchanger, and a recompression blower, to achieve the evaporation crystallization of sodium sulfate solution. The heat exchanger in the MVR evaporation crystallization system 3 is connected to the steam condensate tank 4 to facilitate the unified collection of condensate into the steam condensate tank 4. The feed system 1 is used to transport the sodium sulfate solution to the MVR evaporation crystallization system 3 for processing. To improve the evaporation capacity of the existing MVR evaporation system 3 without changing the existing MVR evaporation crystallization system 3, such as... Figure 1As shown, an external circulation heat exchanger 2 is added between the MVR evaporation crystallization system 3 and the feeding system 1. The material inlet of the external circulation heat exchanger 2 is connected to the feeding system 1 through a material inlet pipe 21 to receive the sodium sulfate solution transported by the feeding system 1 and preheat the sodium sulfate solution. The material outlet of the external circulation heat exchanger 2 is connected to the MVR evaporation crystallization system 3 through a material outlet pipe 22 to input the treated sodium sulfate solution into the MVR evaporation crystallization system 3 for evaporation crystallization. To save costs, the condensate inlet of the external circulation heat exchanger 2 is equipped with a condensate inlet pipe 23 connected to the steam condensate tank 4 to recycle the condensate generated by the MVR evaporation crystallization system 3. The condensate outlet of the external circulation heat exchanger 2 is equipped with a condensate outlet pipe 24 connected to the outside to discharge the condensate, realizing the material preheating-condensate heat exchange cycle. To facilitate the control of the heating temperature of the material by the external circulation heat exchanger 2, the material inlet and outlet of the external circulation heat exchanger 2 are equipped with... The first temperature sensor 25 and the second temperature sensor 26 effectively ensure the material feed temperature by monitoring the inlet and outlet temperatures of the external circulation heat exchanger 2. The material feed temperature can be controlled by adjusting the condensate input. A third temperature sensor 29 and a fourth temperature sensor 210 are installed at the condensate inlet and outlet of the external circulation heat exchanger 2. These sensors monitor the temperature of the condensate entering and exiting the external circulation heat exchanger 2 to adjust the condensate temperature in the condensate tank 4 or to determine whether the external circulation heat exchanger 2 is operating normally. To facilitate real-time monitoring of the external circulation heat exchanger 2's operation, a first pressure sensor 27 and a second pressure sensor 28 are installed at the material inlet and outlet of the external circulation heat exchanger 2. The pressure difference between the material inlet and outlet monitored by these two sensors determines the scaling condition inside the external circulation heat exchanger 2. If the pressure difference is large, the external circulation heat exchanger 2 needs to be cleaned or replaced. This reduces unplanned downtime compared to traditional periodic cleaning methods, ensuring the normal use of the external circulation heat exchanger 2 and extending its service life.

[0017] This evaporation device for sodium sulfate, a byproduct of lithium carbonate production, preheats the sodium sulfate solution in the MVR evaporation and crystallization system 3 by adding an external circulation heat exchanger 2 between the feed system 1 and the MVR evaporation and crystallization system 3. This reduces the evaporation energy consumption in the MVR evaporation and crystallization system 3, improves its evaporation efficiency, and solves the problem of fixed processing capacity and insufficient evaporation capacity of the MVR evaporation system. It effectively increases the sodium sulfate solution throughput and sodium sulfate production. Simultaneously, temperature and pressure sensors are added to the material inlet and outlet of the external circulation heat exchanger 2, and temperature sensors are also added to the condensate inlet and outlet of the external circulation heat exchanger 2. This effectively controls the material feed temperature to ensure the sodium sulfate throughput, slows down the scaling rate of the heat exchanger, improves equipment lifespan, and reduces maintenance costs. Therefore, this evaporation device for sodium sulfate, a byproduct of lithium carbonate production, achieves a triple improvement in evaporation efficiency, processing capacity, and equipment lifespan by adding an external circulation heat exchanger 2 between the feed system 1 and the MVR evaporation and crystallization system 3, combined with the synergistic innovation of temperature and pressure sensors, while retaining the original structure of the MVR system.

[0018] The aforementioned feeding system 1 can utilize existing storage tanks and pipelines for transporting sodium sulfate solution. To ensure dual-line feeding of the MVR evaporation crystallization system 3 without affecting its own processing pipeline connections, i.e., feeding can be done directly through feeding system 1, or the solution can be processed by the external circulation heat exchanger 2 before feeding, such as... Figure 1 As shown, the feeding system 1 includes a sodium sulfate raw solution tank 11. The outlet of the sodium sulfate raw solution tank 11 is equipped with a feed pump 12 connected to the material inlet of the MVR evaporation and crystallization system 3. The outlet of the feed pump 12 is equipped with a first discharge pipe 121 connected to the MVR evaporation and crystallization system 3, and a second discharge pipe 122 connected to the material inlet pipe 21 of the external circulation heat exchanger 2. Through the parallel design of the first discharge pipe 121 and the second discharge pipe 122, different pipelines can be used for feeding channels according to different needs. Furthermore, to achieve flexible switching between direct material supply and preheating supply after use by the external circulation heat exchanger 2, and to ensure uninterrupted production even when one of the material input pipes needs maintenance, such as... Figure 1As shown, the material inlet pipe 21 is equipped with a material inlet control valve 211, and the material outlet pipe 22 is equipped with a material outlet control valve 221; the first discharge pipe 121 is equipped with a material input control valve 1211 and a material output control valve 1212. The material input control valve is located at one end of the first discharge pipe 121 near the feed pump 12, and the material output control valve is located at one end of the first discharge pipe 121 near the MVR evaporation crystallization system 3. When the external circulation heat exchanger 2 is under maintenance, the material inlet control valve 211 is closed to prevent the material from passing through the external circulation heat exchanger 2, and the material input control valve 1211 is opened so that the material is directly input into the MVR evaporation crystallization system 3 from the first discharge pipe 121, ensuring continuous production. Furthermore, the operator can adjust the opening of the material input control valve 1211, the material output control valve 1212, the material inlet control valve 211, and the material outlet control valve 221 to achieve precise control of the feed amount of the MVR evaporation crystallization system 3, thus ensuring the normal operation of the MVR evaporation crystallization system 3.

[0019] To facilitate the control of the condensate inlet flow rate of the external circulation heat exchanger 2 based on the temperature values ​​detected by the first temperature sensor 25 and the second temperature sensor 26, such as Figure 1 As shown, a condensate inlet control valve 231 is provided on the condensate inlet pipe 23, and a condensate outlet control valve 241 is provided on the condensate outlet pipe 24. The amount of condensate input is controlled by controlling the opening of the condensate inlet control valve 231, while the condensate outlet control valve 241 is controlled to discharge the condensate in the external circulation heat exchanger 2 in a timely manner, so as to ensure heat exchange efficiency and preheating effect on materials.

[0020] Furthermore, to facilitate the pressurization and delivery of the low-temperature condensate in the steam condensate tank 4 to the circulating heat exchanger, such as... Figure 1 As shown, a steam condensate pump 232 is also provided on the condensate inlet pipe 23; by adding the steam condensate pump 232, the condensate in the steam condensate tank 4 is transported to the external circulation heat exchanger 2, maintaining the internal circulation power of the external circulation heat exchanger 2, avoiding vaporization of condensate due to insufficient pressure, and reducing pump cavitation damage; and by using the condensate generated by the MVR evaporation crystallization system 3 to enter the external circulation heat exchanger 2 for reuse, costs are saved.

[0021] To further improve the evaporation efficiency of the evaporation device used for sodium sulfate, a byproduct in lithium carbonate production, multiple experiments have shown that controlling the material inlet temperature detected by the first temperature sensor 25 at 50-70℃ and the material outlet temperature detected by the second temperature sensor 26 at 75-90℃ is effective in increasing the sodium sulfate solution throughput and sodium sulfate production. When the material inlet temperature of the external circulation heat exchanger 2 is 50-70℃ and the material outlet temperature is 75-90℃, the throughput of sodium sulfate solution and sodium sulfate production can be effectively increased. When the inlet temperature is below 50℃, the opening of the condensate inlet valve is increased to increase the condensate flow rate; when the temperature is above 70℃, the opening of the condensate inlet valve is decreased to reduce the flow rate. This ensures that the material is always within the optimal evaporation temperature window, avoiding a decrease in evaporation efficiency or equipment overload due to temperature fluctuations, guaranteeing the sodium sulfate throughput, reducing calcium and magnesium ion precipitation in the high-temperature zone, reducing the scaling rate of the external circulation heat exchanger 2, increasing equipment lifespan, and reducing maintenance costs.

[0022] Furthermore, to facilitate real-time monitoring of the usage of the external circulation heat exchanger 2, timely cleaning and replacement, and to ensure the working efficiency of the external circulation heat exchanger 2, thereby guaranteeing the evaporation efficiency of the evaporation device used for the byproduct sodium sulfate in lithium carbonate production, the pressure difference detected between the first pressure sensor 27 and the second pressure sensor 28 is controlled within 0-200 kPa. By detecting the material inlet and outlet pressures of the external circulation heat exchanger 2, the operating status of the heat exchanger is monitored to determine the cleaning cycle of the external circulation heat exchanger 2, thus avoiding excessive scaling on the inner wall that would reduce heat exchange efficiency and affect the evaporation efficiency of the entire evaporation device.

Claims

1. An evaporation apparatus for sodium sulfate, a byproduct of lithium carbonate production; comprising an MVR evaporation crystallization system (3), a feed system (1) connected to the feed inlet of the MVR evaporation crystallization system (3), and a steam condensate tank (4) connected to the condensate outlet of the MVR evaporation crystallization system (3), characterized in that: It also includes an external circulation heat exchanger (2) installed between the feeding system (1) and the MVR evaporation crystallization system (3). The material inlet of the external circulation heat exchanger (2) is provided with a material inlet pipe (21) connected to the discharge end of the feeding system (1), and the material outlet of the external circulation heat exchanger (2) is provided with a material outlet pipe (22) connected to the material inlet of the MVR evaporation crystallization system (3). The condensate inlet of the external circulation heat exchanger (2) is provided with a condensate input pipe (23) connected to the steam condensate tank (4). The condensate outlet of the external circulation heat exchanger (2) is provided with a condensate outlet pipe (24) connected to the outside; the material inlet of the external circulation heat exchanger (2) is provided with a first temperature sensor (25) and a first pressure sensor (27); the material outlet of the external circulation heat exchanger (2) is provided with a second temperature sensor (26) and a second pressure sensor (28); the condensate inlet of the external circulation heat exchanger (2) is provided with a third temperature sensor (29); and the condensate outlet of the external circulation heat exchanger (2) is provided with a fourth temperature sensor (210).

2. The evaporation apparatus for sodium sulfate, a byproduct of lithium carbonate production, as described in claim 1, characterized in that: The feeding system (1) includes a sodium sulfate raw liquid tank (11). The outlet of the sodium sulfate raw liquid tank (11) is provided with a feed pump (12) connected to the material inlet of the MVR evaporation crystallization system (3). The outlet of the feed pump (12) is provided with a first discharge pipe (121) connected to the MVR evaporation crystallization system (3) and a second discharge pipe (122) connected to the material inlet pipe (21) of the external circulation heat exchanger (2).

3. The evaporation apparatus for sodium sulfate, a byproduct of lithium carbonate preparation, as described in claim 2, characterized in that: The material inlet pipe (21) is provided with a material inlet control valve (211), and the material outlet pipe (22) is provided with a material outlet control valve (221); the first discharge pipe (121) is provided with a material input control valve (1211) and a material output control valve (1212). The material input control valve (1211) is located at one end of the first discharge pipe (121) near the feed pump (12), and the material output control valve (1212) is located at one end of the first discharge pipe (121) near the MVR evaporation crystallization system (3).

4. The evaporation apparatus for sodium sulfate, a byproduct of lithium carbonate production, as described in claim 1, characterized in that: The condensate inlet pipe (23) is equipped with a condensate inlet control valve (231), and the condensate outlet pipe (24) is equipped with a condensate outlet control valve (241).

5. The evaporation apparatus for sodium sulfate, a byproduct of lithium carbonate production, as described in claim 4, characterized in that: A steam condensate pump (232) is also provided on the condensate inlet pipe (23).

6. An evaporation apparatus for sodium sulfate, a byproduct of lithium carbonate preparation, as described in any one of claims 1-5, characterized in that: The material inlet temperature detected by the first temperature sensor (25) is controlled at 50-70℃, and the material outlet temperature detected by the second temperature sensor (26) is controlled at 75-90℃.

7. The evaporation apparatus for sodium sulfate, a byproduct of lithium carbonate production, as described in claim 6, characterized in that: The pressure difference detected between the first pressure sensor (27) and the second pressure sensor (28) is controlled within 0-200 kPa.

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