Automatic adjusting and processing device for calcium-magnesium ratio in chlor-alkali brine

Abstract

The application relates to the technical field of primary brine refining of a chlor-alkali device, in particular to a calcium-magnesium ratio automatic adjusting and processing device for chlor-alkali brine, which comprises an adjusting unit and a processing unit; the adjusting unit comprises a first baffle tank and an adjusting tank, the first baffle tank is provided with a brine inlet pipe, a first feed pipe, a second feed pipe and a brine outlet pipe, and the processing unit comprises a second baffle tank, a reaction tank, a clarifying barrel, a buffer tank, a coarse filter and a membrane filter; the second baffle tank is communicated with the adjusting tank through the brine outlet pipe, and the second baffle tank is provided with a third feed pipe and a fourth feed pipe. The application has the effect of controlling the calcium-magnesium ion concentration ratio in the brine.

Description

Technical Field

[0001] This application relates to the technical field of primary brine purification in chlor-alkali plants, and in particular to an automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine. Background Technology

[0002] In the chlor-alkali industry, the core production equipment is the ion-exchange membrane electrolyzer. The main factors affecting the service life of the ion-exchange membrane in the electrolyzer are the calcium, magnesium, silicon, aluminum, iodine, and organic matter contained in the brine. In the current raw salt or brine, the main pollutants are calcium and magnesium. The existing brine refining process can be divided into two parts: primary brine refining and secondary brine refining. Primary brine refining involves reacting sodium hydroxide and sodium carbonate with calcium and magnesium ions in the brine to produce solid substances such as calcium carbonate and magnesium hydroxide. A portion of the solid substances is directly precipitated and discharged in tanks / barrels, while the other portion is filtered through organic / inorganic membranes. Secondary brine refining uses resin to adsorb trace amounts of calcium and magnesium ions to achieve the final removal purpose.

[0003] In related technologies, the generated magnesium hydroxide and calcium carbonate precipitates are discharged into a brine pond and then dried using a brine filter press. During the formation of magnesium hydroxide precipitate, its encapsulating properties can remove some silicon and aluminum. Therefore, a certain amount of magnesium hydroxide is required for precipitate formation. However, excessive magnesium hydroxide will result in overly viscous brine, incomplete filtration, and high water content, causing environmental pollution. Therefore, in actual production, companies often control the calcium-to-magnesium ratio in the brine, primarily by mixing raw salts with different calcium and magnesium contents.

[0004] Regarding the aforementioned technologies, controlling the calcium-magnesium ratio requires mixing raw salts with different calcium and magnesium contents. This necessitates the on-site stockpiling of raw salts from various sources, limiting the procurement of raw salts. Furthermore, different batches of raw salt have varying calcium and magnesium ion contents. During equipment operation, operators need to adjust the addition amounts of sodium hydroxide and sodium carbonate each time the raw salt is replaced. To control the calcium-magnesium ratio, raw salt mixing is necessary, but operators find it difficult to maintain consistency in each mixing process. Utility Model Content

[0005] In order to control the calcium-magnesium ion concentration ratio in brine, this application provides an automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine.

[0006] The automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine provided in this application adopts the following technical solution:

[0007] An automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine includes an adjustment unit for dynamically adjusting the calcium-magnesium ratio and a treatment unit for removing calcium and magnesium.

[0008] The regulating unit includes a first baffle tank and a regulating pool. The first baffle tank and the regulating pool are connected by a pipeline. The first baffle tank is provided with a brine inlet pipe for introducing brine, a first feed pipe for introducing calcium chloride, a second feed pipe for introducing magnesium chloride, and a regulating brine outlet pipe for outputting the regulated brine.

[0009] The processing unit includes a second baffle tank, a reaction tank, a clarification tank, a buffer tank, a coarse filter, and a membrane filter, which are connected in sequence by pipelines. The second baffle tank is connected to the regulating tank through the regulating brine outlet pipe. The second baffle tank is provided with a third feed pipe for introducing sodium hydroxide and a fourth feed pipe for introducing sodium carbonate.

[0010] By adopting the above technical solution, in the regulating unit, calcium chloride or magnesium chloride solution is directly added to the first baffle tank and the regulating tank. The first baffle tank initially mixes the solution, and the regulating tank further dissolves it completely, resulting in a uniform concentration and buffering the brine. Real-time adjustment of calcium and magnesium ion concentrations eliminates the need for mixing with raw salt, solving raw material procurement limitations and avoiding errors from manual proportioning. Combined with an online calcium and magnesium analyzer, the concentration of calcium and magnesium ions in the brine can be monitored in real time. Feedback signals automatically adjust the dosage of calcium chloride / magnesium chloride, achieving precise control of the calcium-magnesium ratio. When the calcium ion concentration is detected to be too high, the system automatically increases the magnesium chloride feed; conversely, it supplements calcium chloride, forming a closed-loop control. In the treatment unit, sodium hydroxide and sodium carbonate are added through the second baffle tank, causing magnesium ions to form magnesium hydroxide precipitate and calcium ions to form calcium carbonate precipitate. By adjusting the calcium-magnesium ratio, the encapsulation properties of the precipitates can be optimized. Magnesium hydroxide precipitate effectively encapsulates impurities such as silicon and aluminum, while a suitable calcium-magnesium precipitation ratio prevents excessively sticky salt mud. Clarification tanks and buffer tanks separate large particles through gravity sedimentation, preventing impurities from entering the subsequent membrane system and extending membrane life. A coarse filter removes residual suspended solids, while a membrane filter further removes trace amounts of calcium and magnesium ions, reducing the calcium and magnesium content of the brine to meet the high purity requirements of the ion-exchange membrane electrolyzer.

[0011] Furthermore, both the first and second baffles have multiple baffles, which are alternately arranged back and forth along the fluid flow direction within the baffles.

[0012] By employing the above technical solution, the alternating arrangement of baffles forces the fluid to undergo multiple directional abrupt changes within the baffle channel, significantly increasing the turbulence intensity. Turbulence breaks down the laminar boundary layer, allowing the calcium and magnesium regulators (calcium chloride / magnesium chloride) to mix rapidly with the brine, avoiding incomplete reactions caused by excessive local concentration gradients. The fluid separation effect at the baffle edges creates vortex structures, generating a Karman vortex street in the downstream region of the baffles, further promoting microscale mixing. This vortex motion accelerates the collision probability of calcium and magnesium ions with hydroxide / carbonate ions, shortening the reaction time.

[0013] Furthermore, the brine inlet pipe is equipped with a first detector for detecting the concentration of calcium and magnesium ions and a first flow meter for measuring the flow rate of the brine.

[0014] By adopting the above technical solution, the first detector directly monitors the concentrations of calcium and magnesium ions in the brine entering the baffle tank, providing real-time data support for subsequent calcium chloride / magnesium chloride dosage. The first flow meter provides real-time feedback on the volumetric flow rate of the brine, and dynamically adjusts the dosing rate based on the calcium and magnesium concentration data.

[0015] Furthermore, the first feed pipe is equipped with a second flow meter for measuring the flow rate of calcium chloride and a first regulating valve, and the second feed pipe is equipped with a third flow meter for measuring the flow rate of magnesium chloride and a second regulating valve.

[0016] By adopting the above technical solution, the second flow meter measures the instantaneous flow rate of the calcium chloride solution in real time, and the third flow meter monitors the flow rate of the magnesium chloride solution. Both data are fed back to the control system. The first and second regulating valves dynamically adjust their openings according to the preset calcium-magnesium ratio to ensure a strict match between the dosages of calcium chloride and magnesium chloride. If the calcium ion concentration in the raw brine is too high, the system automatically reduces the calcium chloride dosage while increasing the magnesium chloride flow rate to adjust the ratio to the target value. If the magnesium ion concentration is insufficient, the magnesium chloride flow rate is reduced, and calcium chloride is added. The calcium and magnesium content varies significantly between different batches of raw salt, making traditional manual proportioning difficult to adapt to. The device compensates for fluctuations in raw salt content in real time through flow meters, ensuring the calcium-magnesium ratio remains stable within the process window and preventing abnormal viscosity or incomplete precipitation of the salt mud due to calcium-magnesium imbalance.

[0017] Furthermore, the brine outlet pipe is equipped with a second detector for detecting the concentration of calcium and magnesium ions and a fourth flow meter for measuring the flow rate of the brine after adjustment.

[0018] By adopting the above technical solution, the second detector directly monitors the calcium and magnesium ion concentrations of the brine at the outlet of the equalization tank, forming a closed-loop control at the end to determine the amount of sodium hydroxide and sodium carbonate to be added, ensuring that calcium and magnesium ions in the brine can be removed. If the detected calcium residue is too high, the system automatically increases the dosage of magnesium chloride; if the magnesium residue is too high, calcium chloride is added to optimize the precipitation ratio. The fourth flow meter provides real-time feedback on the volumetric flow rate of the adjusted brine, and combined with the calcium and magnesium concentration data, dynamically adjusts the operating parameters of the subsequent treatment units. When the flow rate increases, the stirring rate of the reaction tank is automatically increased to ensure sufficient precipitation.

[0019] Furthermore, the third feed pipe is equipped with a fifth flow meter for measuring the flow rate of sodium carbonate and a third regulating valve, and the fourth feed pipe is equipped with a sixth flow meter for measuring the flow rate of sodium hydroxide and a fourth regulating valve.

[0020] By adopting the above technical solution, the fifth flow meter measures the instantaneous flow rate of the sodium carbonate solution in real time, and the sixth flow meter monitors the flow rate of the sodium hydroxide solution. Both data are fed back to the control system. The third and fourth regulating valves dynamically adjust their opening based on the calcium and magnesium ion concentrations in the adjusted brine and the preset excess alkali amount (the amount of sodium hydroxide and sodium carbonate remaining after the reaction), ensuring a strict match between the dosages of sodium carbonate and sodium hydroxide. If a high magnesium ion concentration is detected, the system automatically increases the sodium hydroxide flow rate to remove magnesium ions; if a high calcium ion concentration is detected, the system automatically increases the sodium carbonate flow rate to remove calcium ions. However, excess OH⁻ and CO₃²⁻... 2- This would result in waste and increase the amount of hydrochloric acid added to the downstream system, leading to higher costs. Therefore, the coordinated control of the flow meter and regulating valve is crucial to ensure the co-precipitation of CaCO3 and Mg(OH)2 while strictly controlling OH⁻ and CO3. 2- Excess alkali.

[0021] Furthermore, the pipeline used to connect the reaction tank and the clarification tank is defined as a post-reaction brine pipe. The end of the post-reaction brine pipe that is away from the reaction tank extends into the clarification tank and is located in the middle of the clarification tank. The post-reaction brine pipe is equipped with an online alkali meter for monitoring the excess amount of sodium hydroxide and sodium carbonate.

[0022] By adopting the above technical solution, the brine pipe extends into the settling equilibrium zone in the middle of the clarification tank after the reaction, thus avoiding the unsettled sediment at the bottom and the top. If the brine pipe extends to the bottom of the clarification tank, the turbulence generated by the high-speed liquid inflow will agitate the already settled sludge at the bottom, forming a secondary suspension and increasing the turbidity of the effluent. If the brine pipe extends to the top of the clarification tank, the liquid will flow along the top wall of the tank and be discharged directly through the overflow trough. An online alkalinity analyzer is installed in the pipeline before the brine pipe enters the clarification tank after the reaction to detect the excess alkalinity of the brine in real time, thereby ensuring that the added sodium carbonate and sodium hydroxide can completely react with the calcium and magnesium in the brine, while preventing excessive alkalinity and increased costs.

[0023] Furthermore, the output pipeline at the outlet of the membrane filter is defined as a refined saline outlet pipe, and a third detector for detecting the concentration of calcium and magnesium ions is provided on the refined saline outlet pipe.

[0024] By adopting the above technical solution, the third detector directly monitors the calcium and magnesium ion concentration of the brine at the membrane filter outlet, ensuring that the final refined brine indicators meet the requirements of the electrolysis process. At the same time, it can also detect brine contamination accidents such as membrane damage in a timely manner, so as to ensure that the calcium and magnesium ion concentration entering the downstream system meets the requirements and avoids affecting the downstream system.

[0025] In summary, this application includes at least one of the following beneficial technical effects:

[0026] 1. The device constructs a multi-stage closed-loop control system through the synergistic effect of the regulation and processing units, significantly improving the control accuracy of calcium and magnesium ion concentration. In the regulation unit, the cascaded design of the first baffle tank and the regulating tank, combined with the independent addition of calcium chloride and magnesium chloride, utilizes flow meters to monitor fluid flow in real time and dynamically adjusts the addition ratio through regulating valves. When the online calcium-magnesium analyzer detects that the calcium-magnesium ratio in the brine deviates from the preset value, the system automatically corrects the addition rate of calcium chloride or magnesium chloride, forming a dynamic balance of detection-feedback-regulation. If the calcium ion concentration is too high, the system increases the magnesium chloride flow rate to reduce the calcium-magnesium ratio while simultaneously reducing the calcium chloride addition, ensuring that the calcium-magnesium ratio remains stable within the process window. In the processing unit, the online alkali analyzers monitor the excess alkali in the brine after the reaction in real time, and adjust the addition of sodium hydroxide and sodium carbonate in a coordinated manner to avoid excessive alkali and increased costs. This improves upon the problems of traditional processes relying on manual proportioning and slow response, reduces the fluctuation range of the calcium-magnesium ratio, and enhances the stability of brine purification.

[0027] 2. The baffles arranged alternately at the front and back of the baffle tank optimize the mixing and sedimentation process through forced turbulence and vortex effects. The post-reaction brine pipe between the reaction tank and the clarifier extends into the middle settling zone of the clarifier to ensure full contact between the superalkaline brine and the precipitate, optimizing the encapsulation effect of magnesium hydroxide on silicon and aluminum impurities;

[0028] 3. The treatment unit employs a combination of a coarse filter and a membrane filter, along with an online detector to achieve graded impurity removal. The coarse filter removes residual suspended solids, while the membrane filter further removes trace amounts of calcium and magnesium ions. A third detector is installed at the purified brine outlet of the membrane filter to monitor the outlet water quality in real time, ensuring that the calcium and magnesium content of the final purified brine remains stable. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of an automatic calcium-magnesium ratio adjustment and treatment device in chlor-alkali brine according to an embodiment of this application.

[0030] Figure 2 This is a schematic diagram of the structure of the adjustment unit in the embodiments of this application.

[0031] Figure 3 This is a top view of the first / second baffle channel in the embodiments of this application.

[0032] Figure 4 This is a schematic diagram of the structure of the regulating tank, the second baffle tank, and the regulating brine outlet pipe in the embodiments of this application.

[0033] Figure 5 This is a schematic diagram of the reaction tank, clarification tank, and buffer tank of the processing unit in the embodiments of this application.

[0034] Figure 6 This is a schematic diagram of the structure of the coarse filter and membrane filter of the processing unit in the embodiments of this application.

[0035] Explanation of reference numerals in the attached drawings: 1. Adjustment unit; 11. First baffle trough; 111. Baffle plate; 112. Brine inlet pipe; 1121. First detector; 1122. First flow meter; 113. First feed pipe; 1131. Second flow meter; 1132. First regulating valve; 114. Second feed pipe; 1141. Third flow meter; 1142. Second regulating valve; 12. Adjustment tank; 121. Adjusted brine outlet pipe; 1211. Second detector; 1212. Fourth flow meter; 2. Processing unit; 21. Second baffle; 211. Third feed pipe; 2111. Fifth flow meter; 2112. Third regulating valve; 212. Fourth feed pipe; 2121. Sixth flow meter; 2122. Fourth regulating valve; 22. Reaction tank; 221. Post-reaction brine pipe; 2211. Two-alkali online instrument; 23. Clarification tank; 231. Overflow pipe; 24. Buffer tank; 25. Coarse filter; 26. Membrane filter; 261. Refined brine outlet pipe; 2611. Third detector. Detailed Implementation

[0036] To make the purpose, technical solution, and advantages of this application clearer, the following description is provided in conjunction with the appendix. Figure 1-5 The present application will be further described in detail with reference to the embodiments.

[0037] This application discloses an automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine. (Refer to...) Figure 1 The automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine includes an adjustment unit 1 and a treatment unit 2. The adjustment unit 1 is located upstream of the treatment unit 2 and is used to dynamically adjust the calcium-magnesium ratio. The treatment unit 2 is used to remove calcium and magnesium.

[0038] Reference Figure 1 and Figure 2 The regulating unit 1 includes a first baffle trough 11 and a regulating tank 12, and the first baffle trough 11 and the regulating tank 12 are connected by a pipeline. Figure 3 The first baffle trough 11 contains multiple parallel baffles 111, which are alternately arranged along the flow direction of the brine. The alternating arrangement of the baffles 111 forces the fluid to undergo multiple abrupt changes in direction within the baffle trough, significantly increasing the turbulence intensity, breaking the laminar boundary layer, and allowing the calcium and magnesium regulators to mix rapidly with the brine, avoiding incomplete reactions caused by excessive local concentration gradients. The fluid separation effect at the edges of the baffles 111 forms vortex structures, generating a Karman vortex street downstream of the baffles 111, further promoting microscale mixing. This vortex motion accelerates the collision probability of calcium and magnesium ions with hydroxide / carbonate ions, shortening the reaction time.

[0039] The first baffle trough 11 has a brine inlet pipe 112 connected to its side wall for introducing brine. The brine inlet pipe 112 is equipped with a first detector 1121 for detecting calcium and magnesium ion concentrations and a first flow meter 1122 for measuring the brine flow rate. The first detector 1121 directly monitors the calcium and magnesium ion concentrations in the brine entering the baffle trough, providing real-time data support for subsequent calcium chloride / magnesium chloride dosage. The first flow meter 1122 provides real-time feedback on the volumetric flow rate of the brine, and dynamically adjusts the dosing rate based on the calcium and magnesium concentration data.

[0040] The first baffle trough 11 is connected at its top to a first feed pipe 113 for introducing calcium chloride and a second feed pipe 114 for introducing magnesium chloride. The first feed pipe 113 is equipped with a second flow meter 1131 for measuring the calcium chloride flow rate and a first regulating valve 1132. The second feed pipe 114 is equipped with a third flow meter 1141 for measuring the magnesium chloride flow rate and a second regulating valve 1142. The second flow meter 1131 measures the instantaneous flow rate of the calcium chloride solution in real time, and the third flow meter 1141 monitors the flow rate of the magnesium chloride solution. Both flow meters are fed back to the control system. The first regulating valve 1132 and the second regulating valve 1142 dynamically adjust their openings according to a preset calcium-magnesium ratio to ensure a strict match between the dosages of calcium chloride and magnesium chloride. If the calcium ion concentration in the raw brine is too high, the system automatically reduces the calcium chloride dosage while increasing the magnesium chloride flow rate to adjust the ratio to the target value. If the magnesium ion concentration is insufficient, the magnesium chloride flow rate is reduced, and calcium chloride is added. The calcium and magnesium content varies significantly between different batches of raw salt, making traditional manual proportioning difficult to adapt to. The device compensates for fluctuations in raw salt in real time through a flow meter, ensuring that the calcium-magnesium ratio remains stable within the process window and avoiding abnormal viscosity of salt mud or incomplete precipitation caused by calcium-magnesium imbalance.

[0041] In this embodiment, the concentration of calcium chloride solution is 0-15 wt%, and the concentration of magnesium chloride solution is 0-15 wt%, which is more suitable for flow rate control. The calcium-magnesium ratio is adjustable from 1.5 to 6. By specifying the calcium-magnesium ratio adjustment value, the system can execute an adjustment strategy. When the calcium-magnesium ratio is set to 3, the system determines the calcium-magnesium ratio and calcium-magnesium ion flow rate by measuring the calcium-magnesium ion concentration and flow rate in the brine. When the calcium-magnesium ratio is less than 3, the system calculates how much calcium chloride solution needs to be added to achieve a calcium-magnesium ratio of 3, and then controls the added calcium chloride flow rate through the first regulating valve 1132 to achieve a calcium-magnesium ratio of 3. When the calcium-magnesium ratio is greater than 3, the added magnesium chloride flow rate is controlled through the second regulating valve 1142 to achieve a calcium-magnesium ratio of 3.

[0042] Reference Figure 4The first baffle 11 is connected to the equalization tank 12 by a pipeline. The side of the equalization tank 12 away from the first baffle 11 is connected to an equalization brine outlet pipe 121 for outputting equalization brine. The end of the equalization brine outlet pipe 121 away from the equalization tank 12 is used to connect to the treatment unit 2.

[0043] Combination Figure 1 and Figure 3 The processing unit 2 includes a second baffle trough 21, a reaction tank 22, a clarification tank 23, a buffer tank 24, a coarse filter 25, and a membrane filter 26, which are connected in sequence by pipelines. The second baffle trough 21 has a plurality of baffles 111 arranged in parallel with each other, and the baffles 111 are alternately arranged back and forth in the baffle trough along the flow direction of the brine.

[0044] The second baffle trough 21 is connected to the equalization tank 12 via the brine outlet pipe 121. In order to ensure that the calcium-magnesium ratio of the regulated brine is within the set value and to calculate how much sodium hydroxide and sodium carbonate solution needs to be added to remove calcium and magnesium ions, the brine outlet pipe 121 is equipped with a second detector 1211 for detecting the calcium and magnesium ion concentration and a fourth flow meter 1212 for measuring the brine flow rate after regulated brine.

[0045] The second detector 1211 directly monitors the calcium and magnesium ion concentration in the brine at the outlet of the equalization tank 12, forming a closed-loop control at the end to determine the amount of sodium hydroxide and sodium carbonate to be added, ensuring that calcium and magnesium ions in the brine can be removed. If the calcium residue is detected to be too high (e.g., calcium-magnesium ratio 7:1), the system automatically increases the amount of magnesium chloride added; if the magnesium residue is too high (e.g., calcium-magnesium ratio 1:3.5), calcium chloride is added to optimize the precipitation ratio.

[0046] The fourth flow meter 1212 provides real-time feedback on the volumetric flow rate of the adjusted brine, and dynamically adjusts the operating parameters of the subsequent treatment unit 2 based on calcium and magnesium concentration data. The reaction tank 22 is equipped with an internal stirring mechanism for uniform mixing; when the flow rate increases, the stirring rate of the reaction tank 22 automatically increases to ensure sufficient sedimentation.

[0047] To more precisely control the addition amounts of sodium carbonate and sodium hydroxide solutions, the second baffle 21 is connected to a third feed pipe 211 for introducing sodium carbonate and a fourth feed pipe 212 for introducing sodium hydroxide at its top side. The third feed pipe 211 is equipped with a fifth flow meter 2111 for measuring the sodium carbonate flow rate and a third regulating valve 2112, while the fourth feed pipe 212 is equipped with a sixth flow meter 2121 for measuring the sodium hydroxide flow rate and a fourth regulating valve 2122. In this embodiment, the concentrations of both the sodium carbonate and sodium hydroxide solutions are 5-20 wt%, which is more suitable for flow rate control.

[0048] The fifth flow meter 2111 measures the instantaneous flow rate of the sodium carbonate solution in real time, and the sixth flow meter 2121 monitors the flow rate of the sodium hydroxide solution. Both flow meters are fed back to the control system. The third regulating valve 2112 and the fourth regulating valve 2122 dynamically adjust their openings based on the calcium and magnesium ion concentrations in the regulated brine and the preset excess alkali amount, ensuring a strict match between the dosages of sodium carbonate and sodium hydroxide. If a high magnesium ion concentration is detected, the system automatically increases the sodium hydroxide flow rate to remove magnesium ions; if a high calcium ion concentration is detected, the system automatically increases the sodium carbonate flow rate to remove calcium ions. However, excess OH⁻ and CO₃²⁻... 2- This would result in waste and increase the amount of hydrochloric acid added to the downstream system, leading to higher costs. Therefore, the coordinated control of the flow meter and regulating valve is crucial to ensure the co-precipitation of CaCO3 and Mg(OH)2 while strictly controlling OH⁻ and CO3. 2- Excess alkali.

[0049] Reference Figure 4 and Figure 5 The pipeline connecting the reaction tank 22 and the clarifier tank 23 is a post-reaction brine pipe 221. The end of the post-reaction brine pipe 221 furthest from the reaction tank 22 extends into the clarifier tank 23 and is located in the middle of the clarifier tank 23. The post-reaction brine pipe 221 extends into the settling equilibrium zone in the middle of the clarifier tank 23, thus avoiding the unsettled sediment at the bottom and the top. If the brine pipe extends to the bottom of the clarifier tank 23, the turbulence generated by the high-speed influent will agitate the settled sludge at the bottom, forming a secondary suspension and increasing the turbidity of the effluent. If the brine pipe extends to the top of the clarifier tank 23, the liquid will flow along the top wall of the tank and be discharged directly through the overflow trough.

[0050] The brine pipe 221 after the reaction is equipped with an online alkali meter 2211 to monitor the excess alkali amounts of sodium hydroxide and sodium carbonate. The excess alkali amount is the remaining amount of sodium hydroxide and sodium carbonate. The online alkali meter 2211 is used to determine whether the added sodium carbonate and sodium hydroxide solutions are appropriate. If the excess alkali amounts do not meet the requirements, the calculation formulas for the amount of sodium carbonate and sodium hydroxide solutions added are corrected to ensure that the added amounts can remove calcium and magnesium ions.

[0051] The online alkalinity analyzer 2211 is installed in the pipeline before the brine pipe 221 enters the clarification tank 23 after the reaction. It is used to detect the excess alkalinity (OH⁻ and CO3²⁻ concentration) of the brine after the reaction in real time, so as to ensure that the added sodium carbonate and sodium hydroxide can completely react the calcium and magnesium in the brine, while preventing the excess alkalinity from increasing the cost.

[0052] An overflow pipe 231 is provided between the clarification tank 23 and the buffer tank 24 for communication, and the clarified liquid in the clarification tank 23 overflows from the top into the buffer tank 24. The pipe connecting the buffer tank 24 and the coarse filter 25 is connected to the side wall of the buffer tank 24 near the bottom.

[0053] Reference Figure 5 and Figure 6 In this embodiment, the coarse filter 25 preferably has a mesh size of 30, and the membrane material of the membrane filter 26 is preferably silicon carbide. The output pipe at the outlet of the membrane filter 26 is a refined brine outlet pipe 261, which is equipped with a third detector 2611 for detecting calcium and magnesium ion concentration. The third detector 2611 directly monitors the calcium and magnesium ion concentration of the brine at the outlet of the membrane filter 26. By detecting the brine, it determines whether the brine treatment is qualified. If the detection is unqualified, the brine cannot enter the electrolytic cell, thus ensuring that the final refined brine indicators meet the requirements of the electrolysis process. It also promptly detects brine contamination accidents such as membrane damage, ensuring that the calcium and magnesium ion concentration entering the downstream system meets the requirements and avoiding any impact on the downstream system.

[0054] This device is controlled by an automated system. The amount of calcium chloride, magnesium chloride, sodium hydroxide, and sodium carbonate added to the device is adjusted and controlled by the system using regulating valves after calculating the concentration of calcium and magnesium ions in the brine and the brine flow rate, which can achieve fully automatic operation.

[0055] The implementation principle of the automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine according to an embodiment of this application is as follows: brine purification is achieved through dynamic balance adjustment and multi-stage sedimentation separation. The baffle trough 11 and the adjustment tank 12 of the adjustment unit 1 utilize alternating baffles 111 to create turbulence and vortex effects, accelerating the mixing reaction of calcium chloride, magnesium chloride, and brine. The calcium and magnesium concentration of the influent is monitored in real time by a first detector 1121, and the calcium chloride / magnesium chloride dosage ratio is dynamically adjusted using a flow meter and regulating valve to stabilize the calcium-magnesium ratio. The treatment unit 2 inputs the adjusted brine into the reaction tank 22 through the second baffle trough 21, where sodium hydroxide and sodium carbonate are added to form a synergistic precipitate. After the reaction, the brine pipe 221 extends into the middle of the clarification tank 23 to avoid disturbing the precipitate. The online alkalinity meter 2211 monitors the excess alkalinity to prevent waste. The coarse filter 25 and the silicon carbide membrane filter 26 stage and intercept suspended solids and trace amounts of calcium and magnesium ions. The third detector 2611 at the outlet of the membrane filter 26 ensures that the final brine calcium and magnesium content meets the standard. The system uses an online calcium and magnesium analyzer to adjust the valve opening in conjunction with the excess alkali monitoring data, forming a closed loop of detection-feedback-control, which solves the problems of relying on manual proportioning, high viscosity of salt mud, and serious membrane fouling.

[0056] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine, characterized in that: It includes an adjustment unit (1) for dynamically adjusting the calcium-magnesium ratio and a treatment unit (2) for removing calcium and magnesium; The regulating unit (1) includes a first baffle tank (11) and a regulating tank (12). The first baffle tank (11) and the regulating tank (12) are connected by a pipeline. The first baffle tank (11) is provided with a brine inlet pipe (112) for introducing brine, a first feed pipe (113) for introducing calcium chloride, a second feed pipe (114) for introducing magnesium chloride, and a regulating brine outlet pipe (121) for outputting the regulating brine. The processing unit (2) includes a second baffle tank (21), a reaction tank (22), a clarification tank (23), a buffer tank (24), a coarse filter (25), and a membrane filter (26) connected in sequence by pipelines. The second baffle tank (21) is connected to the regulating tank (12) through the regulating brine outlet pipe (121). The second baffle tank (21) is provided with a third feed pipe (211) for introducing sodium hydroxide and a fourth feed pipe (212) for introducing sodium carbonate.

2. The automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine according to claim 1, characterized in that: Both the first baffle channel (11) and the second baffle channel (21) have multiple baffle plates (111), which are alternately arranged back and forth in the baffle channel along the fluid flow direction.

3. The automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine according to claim 2, characterized in that: The brine inlet pipe (112) is equipped with a first detector (1121) for detecting the concentration of calcium and magnesium ions and a first flow meter (1122) for measuring the flow rate of brine.

4. The automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine according to claim 1, characterized in that: The first feed pipe (113) is equipped with a second flow meter (1131) for measuring the flow rate of calcium chloride and a first regulating valve (1132), and the second feed pipe (114) is equipped with a third flow meter (1141) for measuring the flow rate of magnesium chloride and a second regulating valve (1142).

5. The automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine according to claim 1, characterized in that: The brine outlet pipe (121) is equipped with a second detector (1211) for detecting the concentration of calcium and magnesium ions and a fourth flow meter (1212) for measuring the flow rate of the brine after adjustment.

6. The automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine according to claim 1, characterized in that: The third feed pipe (211) is equipped with a fifth flow meter (2111) for measuring the flow rate of sodium carbonate and a third regulating valve (2112), and the fourth feed pipe (212) is equipped with a sixth flow meter (2121) for measuring the flow rate of sodium hydroxide and a fourth regulating valve (2122).

7. The automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine according to claim 1, characterized in that: The pipeline used to connect the reaction tank (22) and the clarification tank (23) is defined as the post-reaction brine pipe (221). The end of the post-reaction brine pipe (221) that is away from the reaction tank (22) extends into the clarification tank (23) and is located in the middle of the clarification tank (23). The post-reaction brine pipe (221) is equipped with an online alkali meter (2211) for monitoring the excess amount of sodium hydroxide and sodium carbonate.

8. The automatic adjustment and treatment device for the calcium-magnesium ratio in chlor-alkali brine according to claim 1, characterized in that: The output pipeline at the outlet of the membrane filter (26) is defined as the refined brine outlet pipe (261), and the refined brine outlet pipe (261) is equipped with a third detector (2611) for detecting the concentration of calcium and magnesium ions.

Images