Device for increasing sulfate radical concentration of dechlorinated light salt brine concentrated solution

Abstract

The utility model provides a device for increasing the sulfate radical concentration of a dechlorinated light salt brine concentrated solution, which comprises an electric membrane stack, a pressure supply pump I and a nanofiltration membrane component I. The electric membrane stack, the pressure supply pump I and the nanofiltration membrane component I are sequentially connected through a pipeline; the electric membrane stack is used for reducing the ratio of sodium chloride to sodium sulfate of the dechlorinated light salt brine, and the pressure supply pump I is matched with the nanofiltration membrane assembly I to concentrate sulfate radicals of the desalted dechlorinated light salt brine. The reverse electrodialysis device is used as a concentration diffusion device, so that the ratio of sodium chloride to sodium sulfate in the dechlorinated light salt brine is reduced, the solution with the reduced sodium chloride concentration is subjected to nanofiltration membrane concentration, and the concentration limit can break through the concentration of sodium sulfate in the traditional denitration process and can reach more than 180g / L.

Description

Technical Field

[0001] This utility model relates to the field of sulfate concentration technology, and in particular to a device for increasing the sulfate concentration of dechlorinated brine concentrate. Background Technology

[0002] Dechlorinated brine is the effluent from sodium hydroxide production using ion-exchange membranes in chlor-alkali enterprises. It contains 200 g / L of sodium chloride and 10 g / L of sodium sulfate. All brine in chlor-alkali enterprises operates in a closed-loop cycle, and the added salts contain a certain amount of sulfate. If the sulfate in the brine is not treated, the sulfate content in the circulating brine system will continuously increase. Excessive sulfate levels can cause malfunctions in the ion-exchange membrane electrolyzer. Therefore, a portion of the dechlorinated brine needs to be drawn out for sulfate concentration, followed by sulfate crystallization and conversion into solid sulfate, which is then discharged from the brine system. Currently, there are two sulfate concentration technologies: (1) using nanofiltration membranes to separate sulfate from sodium chloride; (2) using solvent evaporation to concentrate sulfate.

[0003] In the process of sodium sulfate concentration using nanofiltration membranes, the sodium chloride concentration in the solution system is a key limiting factor. This is because, in the same solution, both sodium chloride and sodium sulfate have sodium ions as their cations. When the sodium chloride concentration is too high, the common ion effect restricts the solubility of sodium sulfate. For a pure sodium sulfate solution without sodium chloride, the concentration can reach over 350 g / L. However, when the sodium chloride concentration is 200 g / L, the solubility of sodium sulfate cannot exceed 150 g / L. This is also why, in traditional dechlorination and denitrification separation methods for brine, the sodium sulfate concentration in the nanofiltration membrane's concentrate cannot be too high.

[0004] For the same reasons mentioned above, the sulfate concentration method achieved through solvent evaporation is even more limited. Even after evaporating the dechlorinated brine and concentrating it until sodium chloride reaches saturation crystallization, the concentration of sodium sulfate in the concentrated solution cannot exceed 15 g / L. Currently, some researchers use a dilution and reconcentration method. This involves diluting both sodium chloride and sodium sulfate by adding additional water, and then using a nanofiltration membrane to concentrate the sodium sulfate. However, this method inevitably introduces a large amount of dilution water, disrupting the original water balance of the chlor-alkali plant. Furthermore, the amount of water treated by the nanofiltration membrane increases significantly, drastically amplifying system consumption and leading to unnecessary expenses.

[0005] To address this issue, we propose a device to increase the sulfate concentration in the dechlorinated brine concentrate, thereby solving the problem in existing technologies where a high concentration of sodium sulfate solution cannot be obtained during the denitrification process of dechlorinated brine. Utility Model Content

[0006] In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide a device for increasing the sulfate concentration of dechlorinated brine concentrate, in order to solve the problem that high-concentration sodium sulfate solution cannot be obtained in the denitrification process of dechlorinated brine in the prior art.

[0007] To achieve the above and other related objectives, this utility model provides a device for increasing the sulfate concentration of dechlorinated brine concentrate, comprising: an electro-membrane stack, a pressure pump, and a nanofiltration membrane assembly, wherein the electro-membrane stack, the pressure pump, and the nanofiltration membrane assembly are connected in sequence via pipelines.

[0008] The electrofiltration membrane stack is used to reduce the ratio of sodium chloride to sodium sulfate in the dechlorinated brine. The pressure pump works in conjunction with the nanofiltration membrane module to concentrate the sulfate in the dechlorinated brine.

[0009] Preferably, the interior of the electrocoagulation membrane stack has an anode chamber, a desalination chamber, and a cathode chamber arranged sequentially from left to right, and a concentration chamber is also provided on both sides of the desalination chamber;

[0010] The desalination chamber and the two concentration chambers are equipped with several spaced and alternately arranged cation exchange membranes and anion exchange membranes.

[0011] Preferably, a sodium hydroxide solution of 2 mol / L to 10 mol / L is introduced into the anode chamber, a hydrochloric acid solution is introduced into the cathode chamber, a dechlorinated dilute salt solution is introduced into the desalination chamber, and a dilute NaCl solution of 0.01 to 0.1 mol / L is introduced into the concentration chamber.

[0012] Preferably, the concentration of sodium hydroxide solution in the anode chamber is maintained at 0.5 mol / L-5 mol / L, and the concentration of hydrochloric acid solution in the cathode chamber is maintained at 0.5 mol / L-5 mol / L.

[0013] Preferably, the solution on the desalination chamber side and the solution on the concentration chamber side are in a countercurrent manner, and the concentration difference between the desalination chamber and the two concentration chambers is maintained at more than 20 g / L.

[0014] Preferably, another output end of the electrofiltration membrane stack is connected to the input end of a second pressure pump via a pipeline. The output end of the second pressure pump is connected to the input end of a second nanofiltration membrane module via a pipeline. One output end of the first nanofiltration membrane module and one output end of the second nanofiltration membrane module are merged via a pipeline and then connected to the input end of the material separation and concentration device. One output end of the material separation and concentration device is connected to a heating device via a pipeline.

[0015] Preferably, the other output end of the nanofiltration membrane module two is connected to the other output end of the material separation and concentration equipment through a pipeline and then connected to an input pipeline of the electrofiltration membrane stack.

[0016] As described above, the device disclosed in this utility model for increasing the sulfate concentration of dechlorinated brine concentrate has the following features:

[0017] Beneficial effects:

[0018] This invention uses a reverse electrodialysis device as a concentration diffusion device to reduce the ratio of sodium chloride to sodium sulfate in dechlorinated brine. The solution with reduced sodium chloride concentration is then concentrated by nanofiltration membrane. Its concentration limit can break through the sodium sulfate concentration in traditional denitrification processes, reaching a maximum of over 180 g / L.

[0019] At the same time, this invention can also obtain extremely high concentrations of sodium sulfate solution, providing more possibilities for subsequent denitrification production.

[0020] Therefore, this utility model effectively overcomes the various shortcomings of the prior art and has high industrial application value. Attached Figure Description

[0021] Figure 1 The diagram shows the overall structure of a device for increasing the sulfate concentration in dechlorinated brine concentrate according to this invention.

[0022] Figure 2 The diagram shown is a schematic diagram of the sulfate concentration structure of a device for increasing the sulfate concentration of dechlorinated brine concentrate according to this invention.

[0023] Figure 3 The diagram shows the solution flow of a device for increasing the sulfate concentration in a dechlorinated brine concentrate according to this invention.

[0024] Figure 4 The diagram shown is a structural diagram of an electro-film stack for a device of this invention for increasing the sulfate concentration in dechlorinated brine concentrate.

[0025] Component designation explanation

[0026] 1. Electrofiltration membrane stack; 2. Pressure pump 1; 3. Nanofiltration membrane module 1;

[0027] 10. Anode chamber; 11. Desalination chamber; 12. Cathode chamber; 13. Concentration chamber; 14. Cation exchange membrane; 15. Anion exchange membrane;

[0028] 4. Pressure pump II; 5. Nanofiltration membrane module II; 6. Material separation and concentration equipment; 7. Heating equipment. Detailed Implementation

[0029] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.

[0030] Please see Figures 1 to 4 It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the scope of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of this invention, should still fall within the scope of the disclosed technical content. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of this invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this invention.

[0031] The arrows in the accompanying diagram indicate the direction of solution flow.

[0032] like Figure 1-4 As shown, this utility model provides a device for increasing the sulfate concentration of dechlorinated brine concentrate, comprising: an electro-membrane stack 1, a pressure pump 2, and a nanofiltration membrane module 3, which are connected sequentially via pipelines. The electro-membrane stack 1 is used to reduce the sodium chloride to sodium sulfate ratio in the dechlorinated brine. The pressure pump 2 works in conjunction with the nanofiltration membrane module 3 to concentrate the sulfate in the dechlorinated brine. In use, after the dechlorinated brine is introduced into the electro-membrane stack 1, the sodium chloride concentration of the dechlorinated brine decreases, transforming it into a dilute solution. This solution then flows through the three-phase electrically driven pressure pump 2 and nanofiltration membrane module 3 to concentrate the sulfate concentration, transforming it into two solutions. One of these solutions is a dechlorinated brine concentrate containing 30-100 g / L sodium chloride and 60-200 g / L sodium sulfate. This structure enables the reduction of the sodium chloride to sodium sulfate ratio in dechlorinated brine. The solution with reduced sodium chloride concentration is then concentrated by nanofiltration membrane. Its concentration limit can exceed the sodium sulfate concentration in traditional denitrification processes, reaching a maximum of over 180 g / L.

[0033] In one embodiment, please refer to Figure 4The electrochemical membrane stack 1 contains, from left to right, an anode chamber 10, a desalination chamber 11, and a cathode chamber 12. Concentration chambers 13 are located on both sides of the desalination chamber 11. Several alternating cation exchange membranes 14 and anion exchange membranes 15 are installed in the desalination chamber 11 and the two concentration chambers 13. The anion exchange membranes 15 in the electrochemical membrane stack 1 are anion exchange membranes with monovalent ion separation capabilities, achieving a chloride-sulfate separation coefficient of less than 0.01. The introduced dechlorinated brine has a sodium chloride concentration of 200-210 g / L and a sodium sulfate concentration of 8-12 g / L. After passing through the electrochemical membrane stack 1, two solutions are output: one with a sodium chloride concentration of 30-100 g / L and a sodium sulfate concentration of 8-12 g / L, and the other with a sodium chloride concentration of 100-160 g / L and a sodium sulfate concentration of 0-0.5 g / L.

[0034] A solution with a sodium chloride concentration of 30-100 g / L and a sodium sulfate concentration of 8-12 g / L is passed through a three-phase electrically driven pressure pump 2 and a nanofiltration membrane module 3 to concentrate the sulfate concentration, converting it into two solutions: one is a dechlorinated brine concentrate containing a sodium chloride concentration of 30-100 g / L and a sodium sulfate concentration of 60-200 g / L, and the other is a nanofiltration permeate containing a sodium chloride concentration of 100-160 g / L and a sodium sulfate concentration of 0.5-2 g / L. The dechlorinated brine concentrate containing a sodium chloride concentration of 30-100 g / L and a sodium sulfate concentration of 60-200 g / L is equivalent to the concentrate from a traditional dechlorinated brine concentration device.

[0035] In one embodiment, please refer to Figure 4 A sodium hydroxide solution of 2 mol / L to 10 mol / L is introduced into the anode chamber 10, a hydrochloric acid solution is introduced into the cathode chamber 12, a dechlorination dilute brine solution is introduced into the desalination chamber 11, and a dilute NaCl brine solution of 0.01 to 0.1 mol / L is introduced into the concentration chamber 13.

[0036] In one embodiment, please refer to Figure 4 The concentration of sodium hydroxide solution in anode chamber 10 is maintained at 0.5 mol / L-5 mol / L, and the concentration of hydrochloric acid solution in cathode chamber 12 is maintained at 0.5 mol / L-5 mol / L.

[0037] In one embodiment, please refer to Figure 4 The solution on the desalination chamber 11 and the solution on the concentration chamber 12 are in a countercurrent manner, and the concentration difference between the two sides is maintained above 20 g / L.

[0038] In one embodiment, please refer to Figure 1-3Another output end of the electrofiltration membrane stack 1 is connected to the input end of the pressure pump 4 via a pipeline. The output end of the pressure pump 4 is connected to the input end of the nanofiltration membrane module 5 via a pipeline. One output end of the nanofiltration membrane module 3 and one output end of the nanofiltration membrane module 5 are connected to the input end of the material separation and concentration device 6 via a pipeline. One output end of the material separation and concentration device 6 is connected to the heating device 7 via a pipeline. Another stream of solution output from electrofiltration membrane stack 1 flows through pressure pump 2 4 and nanofiltration membrane module 2 5 for sulfate purification, resulting in two separate solutions with high and low sodium sulfate concentrations. The low-sodium-sulfate solution is combined with the nanofiltration permeate separated from nanofiltration membrane module 3 (sodium chloride concentration 100-160 g / L, sodium sulfate concentration 0.5-2 g / L) and then fed into a three-phase electrically driven material separation and concentration device 6 for further separation and concentration, transforming into two solutions: a lean solution with sodium chloride concentration of 0-2 g / L and sodium sulfate concentration of 0-0.1 g / L, and a concentrated solution with sodium chloride concentration of 190-220 g / L and sodium sulfate concentration of 2-5 g / L. The concentrated solution with sodium chloride concentration of 190-220 g / L and sodium sulfate concentration of 2-5 g / L can be sent to heating device 7 and then externally fed into the brine system; this solution is equivalent to the permeate from a traditional dechlorination brine concentration device.

[0039] The material separation and concentration equipment can be selected from: a) MVR evaporation equipment, which includes an evaporation chamber, a heating chamber, and an electrically driven MVR compressor, enabling material separation using electricity to turn the solution into evaporative condensate and concentrated liquid; b) electrodialysis equipment, which includes an electrodialysis membrane stack, a drive power supply, and a pressure pump (electrically driven), enabling material separation using electricity to turn a solution into a dilute liquid and a concentrated liquid. Heating equipment 7 can be a resistance water heater, which heats the water by applying electricity.

[0040] In one embodiment, please refer to Figure 1-3 The other output end of nanofiltration membrane module 2 5 is connected to the other output end of material separation and concentration equipment 6 via a pipeline and then connected to one input pipeline of electro-membrane stack 1. During use, the lean solution (0-2 g / L sodium chloride and 0-0.1 g / L sodium sulfate) separated by material separation and concentration equipment 6 is combined with the solution with high sodium sulfate content output from nanofiltration membrane module 2 5 and then used as makeup water for NaCl dilute brine before being sent to electro-membrane stack 1.

[0041] In the anode chamber 10 of the electrolytic membrane stack 1, hydroxide ions undergo an electrolytic oxidation reaction to produce oxygen, while in the cathode chamber 12, hydrogen ions undergo an electrolytic reduction reaction to produce hydrogen.

[0042] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. An apparatus for increasing the sulfate concentration in dechlorinated brine concentrate, characterized in that, include: Electro-membrane stack (1), pressure pump one (2), and nanofiltration membrane module one (3) are connected in sequence through pipelines; The electro-membrane stack (1) is used to reduce the ratio of sodium chloride to sodium sulfate in the dechlorinated brine. The pressure pump (2) works in conjunction with the nanofiltration membrane assembly (3) to concentrate the sulfate in the dechlorinated brine.

2. The apparatus for increasing the sulfate concentration of dechlorinated brine concentrate according to claim 1, characterized in that: The interior of the electrofilm stack (1) is provided with an anode chamber (10), a desalination chamber (11) and a cathode chamber (12) arranged from left to right. Concentration chambers (13) are also provided on both sides of the desalination chamber (11). The desalination chamber (11) and the two concentration chambers (13) are provided with a number of spaced and alternately arranged cation exchange membranes (14) and anion exchange membranes (15).

3. The apparatus for increasing the sulfate concentration of dechlorinated brine concentrate according to claim 2, characterized in that: A sodium hydroxide solution of 2 mol / L to 10 mol / L is introduced into the anode chamber (10), a hydrochloric acid solution is introduced into the cathode chamber (12), a dechlorinated dilute salt solution is introduced into the desalination chamber (11), and a dilute NaCl solution of 0.01 to 0.1 mol / L is introduced into the concentration chamber (13).

4. The apparatus for increasing the sulfate concentration of dechlorinated brine concentrate according to claim 3, characterized in that: The concentration of sodium hydroxide solution in the anode chamber (10) is maintained at 0.5 mol / L-5 mol / L, and the concentration of hydrochloric acid solution in the cathode chamber (12) is maintained at 0.5 mol / L-5 mol / L.

5. The apparatus for increasing the sulfate concentration of dechlorinated brine concentrate according to claim 3, characterized in that: The solution on the desalination chamber (11) side and the solution on the two concentration chambers (13) side are in a countercurrent manner, and the concentration difference between the desalination chamber (11) and the two concentration chambers (13) is maintained above 20 g / L.

6. The apparatus for increasing the sulfate concentration of dechlorinated brine concentrate according to claim 1, characterized in that: The other output end of the electro-membrane stack (1) is also connected to the input end of the pressure pump two (4) through a pipeline. The output end of the pressure pump two (4) is connected to the input end of the nanofiltration membrane assembly two (5) through a pipeline. One output end of the nanofiltration membrane assembly one (3) and one output end of the nanofiltration membrane assembly two (5) are connected to the input end of the material separation and concentration device (6) through a pipeline. One output end of the material separation and concentration device (6) is connected to the heating device (7) through a pipeline.

7. The apparatus for increasing the sulfate concentration of dechlorinated brine concentrate according to claim 6, characterized in that: The other output end of the nanofiltration membrane module 2 (5) is connected to the other output end of the material separation and concentration device (6) through a pipeline and then connected to an input pipeline of the electro-membrane stack (1).

Images