Chlor-alkali ionic membrane salt water stepped acid adding system

Abstract

The utility model discloses a chlor-alkali ionic membrane salt water stepped acid adding system which comprises a fresh salt water tank, a first water outlet pipe connected with the fresh salt water tank, a light salt water tank, a second water outlet pipe connected with the light salt water tank, and a mixing pipe converging the first water outlet pipe and the second water outlet pipe, the acid adding system further comprises a diluted hydrochloric acid tank, a first connecting pipe connected with the diluted hydrochloric acid tank and the mixing pipe, and a second connecting pipe connected with the diluted hydrochloric acid tank and a water inlet of the electrolytic bath, so that a mixed solution formed by mixing refined salt water in the fresh salt water tank and light salt water in the light salt water tank is subjected to secondary acid adding. Compared with the prior art, the chlor-alkali ionic membrane salt water stepped acid adding system disclosed by the utility model has the advantages that the PH value can be more favorably controlled, the PH value control accuracy is improved, and on the other hand, the workload of manually adjusting the flow of diluted hydrochloric acid can also be reduced.

Description

Technical Field

[0001] The utility model relates to a chlor-alkali ion membrane brine step acidification system, belonging to the technical field of chlor-alkali industrial brine electrolysis production. Background Art

[0002] The ion-exchange membrane electrolyzer of the chlor-alkali plant is affected by the catholyte OH - Reverse osmosis to the anode chamber through the ion membrane reduces the current efficiency in order to neutralize the OH migrating from the cathode chamber to the anode chamber. - , hydrochloric acid needs to be added to the anode solution.

[0003] The current method of adding hydrochloric acid is to add hydrochloric acid at the inlet of the electrolytic cell and mix it with the refined brine by colliding it with the pipe elbow. This requires regular measurement of the acidity at the anode inlet and timely adjustment of the hydrochloric acid flow rate. Because the hydrochloric acid concentration remains unchanged, the pH value of the electrolytic cell anolyte fluctuates after the acid is added. This will cause corrosion of the anode coating of the ion-exchange membrane electrolyzer, shorten the service life of the ion-exchange membrane electrolyzer, and cause the hydroxyl acid layer on the cathode side to protonate and lose its conductive properties, resulting in pinholes, supersaturation of Cl2 in the anode chamber, and even cause the electrolytic cell to explode.

[0004] In view of this, it is indeed necessary to improve the existing chlor-alkali ion membrane brine acidification system to solve the above problems. Utility Model Content

[0005] In order to solve the above technical problems, the utility model provides a chlor-alkali ion membrane brine step acidification system, which can reduce manual operations and also avoid excessive fluctuations in the pH value of the electrolytic cell anode liquid, thereby shortening the service life of the ion membrane electrolytic cell.

[0006] The technical solution of the utility model is:

[0007] A chlor-alkali ion-exchange membrane brine step-acidification system includes a fresh brine tank and a first outlet pipe connected to the fresh brine tank, a dilute brine tank and a second outlet pipe connected to the dilute brine tank, and a mixing pipe that merges the first and second outlet pipes, wherein the outlet of the mixing pipe is connected to an electrolytic cell. The acidification system also includes a dilute hydrochloric acid tank, a first access pipe connecting the dilute hydrochloric acid tank and the mixing pipe, and a second access pipe connecting the dilute hydrochloric acid tank and the water inlet of the electrolytic cell, so as to perform secondary acidification on a mixed solution formed by mixing the refined brine in the fresh brine tank and the dilute brine in the dilute brine tank. By performing secondary acidification on the mixed solution, the pH value of the mixed solution is gradually adjusted, thereby ensuring the accuracy of the adjustment and reducing manual operation.

[0008] As a further improvement of the present invention, the acid addition system also includes a first remote transmission component arranged at the water outlet of the mixing tube, and a first regulating valve connected in series with the first remote transmission component is correspondingly provided on the first access pipe. The first regulating valve is configured to adjust the flow rate of dilute hydrochloric acid in the first access pipe according to the pH value of the mixed solution monitored by the first remote transmission component, and then adjust the pH value of the mixed solution in the mixing tube.

[0009] As a further improvement of the present invention, the mixing tube includes a mixing area and a water outlet area. The mixing area is configured for the refined brine and the light brine to mix and react to form a mixed solution. The water outlet area is used to transfer the mixed solution after the reaction is completed to the electrolytic cell. The water outlet of the first access pipe is connected to the mixing area, and the first field remote transmission component is arranged in the water outlet area. In the flow direction of the mixed solution, the first remote transmission component is located between the water outlet of the first access pipe and the water outlet of the second access pipe.

[0010] As a further improvement of the present invention, the first remote transmission component and the first regulating valve adjust the pH value of the mixed solution in the mixing tube to between 5 and 7.

[0011] As a further improvement of the present invention, the water inlet of the electrolytic cell is further provided with a second remote transmission component, and the second water outlet pipe is correspondingly provided with a second regulating valve connected in series with the second remote transmission component. The second regulating valve is configured to adjust the flow of the brine tank according to the flow of the mixed solution monitored by the second remote transmission component, and then adjust the mixing ratio of the refined brine and the brine.

[0012] As a further improvement of the present invention, the mixing ratio of the refined brine and the light brine is 4:1-6:1.

[0013] As a further improvement of the present invention, the second water outlet pipe is further provided with a booster assembly located between the second regulating valve and the brine tank, so that while the first water outlet pipe transports the refined brine by self-pressure, the brine is transported through the booster assembly and the second regulating valve.

[0014] As a further improvement of the present invention, a third remote transmission component is further provided at the water outlet of the electrolytic cell, and a third regulating valve connected in series with the third remote transmission component is correspondingly provided on the second access pipe. The third remote transmission component is used to monitor the pH value of the brine flowing out of the electrolytic cell, and the third regulating valve is configured to adjust the flow rate of dilute hydrochloric acid in the second access pipe according to the pH value, and then adjust the pH value of the mixed solution entering the electrolytic cell.

[0015] As a further improvement of the present invention, the water outlet of the electrolytic cell is connected to the brine tank so that the brine treated by electrolysis in the electrolytic cell is stored in the brine tank.

[0016] As a further improvement of the present invention, the third remote transmission component and the third regulating valve adjust the pH value of the mixed solution entering the electrolytic cell to between 2.5 and 3.

[0017] The beneficial technical effect of the utility model is that a chlor-alkali ion membrane brine step acidification system of the utility model gradually adjusts the pH value of the mixed solution by performing secondary acidification on a mixed solution of refined brine and dilute brine. On the one hand, it is more conducive to controlling the pH value and improving the accuracy of pH value control. On the other hand, it can achieve uniform mixing of dilute hydrochloric acid and brine, ensure constant pH of the brine, avoid corrosion of anode plates, and extend the service life of the electrolytic cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural diagram of a chlor-alkali ion membrane brine step acidification system that conforms to the preferred embodiment of the utility model. DETAILED DESCRIPTION

[0019] In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0020] See also Figure 1 As shown, the utility model provides a chlor-alkali ion membrane brine step acidification system 100, which includes a fresh brine tank 1 and a first water outlet pipe 14 connected to the fresh brine tank 1, a desalted brine tank 2 and a second water outlet pipe 21 connected to the desalted brine tank 2, and a mixing pipe 5 that converges the first water outlet pipe 14 and the second water outlet pipe 21, and the water outlet of the mixing pipe 5 is connected to the electrolytic cell 4.

[0021] Preferably, the fresh brine tank 1 stores refined brine from the brine process, and the desalted brine tank 2 stores chlorinated desalted brine from the electrolytic cell 4. Therefore, the outlet of the electrolytic cell 4 is connected to the desalted brine tank 2 so that the desalted brine electrolyzed by the electrolytic cell 4 is stored in the desalted brine tank 2. In other words, the brine obtained by mixing the refined brine with the chlorinated desalted brine is electrolyzed, and then the electrolyzed desalted brine is stored in the desalted brine tank for reuse.

[0022] The water inlet of the electrolytic cell 4 is equipped with a second remote transmission component 12. The second water outlet pipe 21 is correspondingly equipped with a second regulating valve 13 connected in series with the second remote transmission component 12. The second regulating valve 13 is configured to adjust the flow rate of the dilute brine based on the flow rate of the mixed solution monitored by the second remote transmission component 12, thereby adjusting the mixing ratio of the refined brine and dilute brine. According to experimental results, the mixing ratio of the refined brine and dilute brine is 4:1-6:1. Preferably, the mixed solution is salt water.

[0023] The second water outlet pipe 21 is also provided with a pressurizing assembly 6 located between the second regulating valve 13 and the dilute brine tank 2. This allows the first water outlet pipe 14 to deliver the refined brine under its own pressure while simultaneously delivering the dilute brine through the pressurizing assembly 6 and the second regulating valve 13. Preferably, the pressurizing assembly 6 is a booster pump for pumping the dilute brine into the mixing pipe 5. Therefore, the delivery methods of the first water outlet pipe 14 and the second water outlet pipe 21 are different.

[0024] Specifically, the acid addition system 100 also includes a dilute hydrochloric acid tank 3, a first access pipe 31 connecting the dilute hydrochloric acid tank 3 and the mixing pipe 5, and a second access pipe 32 connecting the dilute hydrochloric acid tank 3 and the water inlet of the electrolytic cell 4, so as to perform secondary acid addition on the mixed solution formed by mixing the refined brine in the fresh brine tank 1 and the dilute brine in the dilute brine tank 2. This secondary acid addition can gradually adjust the pH value of the mixed solution and accurately control the pH of the mixed solution. At the same time, it can also ensure that the dilute hydrochloric acid and brine are evenly mixed, ensuring a constant pH of the brine, avoiding corrosion of the anode plate, and extending the service life of the electrolytic cell.

[0025] A hydrochloric acid pump 7 is further provided between the dilute hydrochloric acid tank 3 and the first and second inlet pipes 31 and 32 . The hydrochloric acid pump 7 is used to pump dilute hydrochloric acid into the first and second inlet pipes 31 and 32 .

[0026] Preferably, the acid addition system 100 includes a first remote transmission component 8 provided at the water outlet of the mixing tube 5, and a first regulating valve 9 connected in series with the first remote transmission component 8 is correspondingly provided on the first access pipe 31. The first regulating valve 9 is configured to adjust the flow rate of the dilute hydrochloric acid in the first access pipe 31 according to the pH value of the mixed solution monitored by the first remote transmission component 8. Since the concentration of the dilute hydrochloric acid does not change, the pH value of the mixed solution in the mixing tube 5 can be adjusted by adjusting the flow rate of the dilute hydrochloric acid. Therefore, by providing the first remote transmission component 8 and the first regulating valve 9 in series, automatic control can be performed through an existing control system such as a PLC, so that the pH value of the mixed solution is always maintained within a predetermined range. Preferably, the first remote transmission component 8 and the first regulating valve 9 adjust the pH value of the mixed solution in the mixing tube 5 to between 5 and 7.

[0027] The mixing tube 5 includes a mixing area and a water outlet area. The mixing area is configured to allow the refined brine and the dilute brine to mix and react to form a mixed solution. The water outlet area is used to transfer the mixed solution after the reaction is completed to the electrolytic cell 4. The outlet of the first access pipe 31 is connected to the mixing area. The first remote transmission component 8 is disposed in the water outlet area. In the direction of flow of the mixed solution, the first remote transmission component 8 is located between the outlet of the first access pipe 31 and the outlet of the second access pipe 32. In this way, the pH value of the mixed solution in the mixing tube 5 can be precisely adjusted to ensure uniform mixing of the dilute hydrochloric acid and the brine.

[0028] A third remote transmission assembly 10 is also provided at the water outlet of the electrolytic cell 4. A third regulating valve 11 is correspondingly provided on the second access pipe 32 and is connected in series with the third remote transmission assembly 10. The third remote transmission assembly 10 is used to monitor the pH value of the dilute brine flowing out of the electrolytic cell 4. The third regulating valve 11 is configured to adjust the flow rate of dilute hydrochloric acid in the second access pipe 32 according to the pH value, thereby adjusting the pH value of the mixed solution entering the electrolytic cell 4. Preferably, the third remote transmission assembly 10 and the third regulating valve 11 adjust the pH value of the mixed solution entering the electrolytic cell 4 to between 2.5 and 3.

[0029] In summary, the chlor-alkali ion membrane brine step-by-step acidification system of the present invention adjusts the pH value of the mixed solution in a step-by-step manner through two acid additions, so that the dilute hydrochloric acid can be fully mixed with the mixed solution (i.e., brine), ensuring the constant pH of the brine, avoiding corrosion of the anode plate, and extending the service life of the electrolytic cell; and through the setting of the first remote transmission component 8, the first regulating valve 9, the second remote transmission component 12, the second regulating valve 13, the third remote transmission component 10, and the third regulating valve 11, it can cooperate with existing control systems such as PLC, microcontroller and industrial PC to realize automatic control of the entire process and reduce manual participation.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A chlor-alkali ion-exchange membrane brine step acidification system, characterized in that: The invention comprises a fresh brine tank (1) and a first water outlet pipe (14) connected to the fresh brine tank (1), a desalinated brine tank (2) and a second water outlet pipe (21) connected to the desalinated brine tank (2), and a mixing pipe (5) for merging the first water outlet pipe (14) and the second water outlet pipe (21), wherein the water outlet of the mixing pipe (5) is connected to the electrolytic cell (4). The acid addition system (100) further comprises a dilute hydrochloric acid tank (3), a first access pipe (31) connected to the dilute hydrochloric acid tank (3) and the mixing pipe (5), and a second access pipe (32) connected to the dilute hydrochloric acid tank (3) and the water inlet of the electrolytic cell (4), so as to perform secondary acid addition on a mixed solution formed by mixing the refined brine in the fresh brine tank (1) and the desalinated brine in the desalinated brine tank (2).

2. The chlor-alkali ion-exchange membrane brine step acidification system according to claim 1, characterized in that: The acid addition system (100) further comprises a first remote transmission component (8) arranged at the water outlet of the mixing tube (5); a first regulating valve (9) connected in series with the first remote transmission component (8) is correspondingly provided on the first access pipe (31); the first regulating valve (9) is configured to regulate the flow of the dilute hydrochloric acid in the first access pipe (31) according to the pH value of the mixed solution monitored by the first remote transmission component (8), thereby regulating the pH value of the mixed solution in the mixing tube (5).

3. The chlor-alkali ion-exchange membrane brine step acidification system according to claim 2, characterized in that: The mixing tube (5) includes a mixing area and a water outlet area. The mixing area is configured for the refined brine and the light brine to mix and react to form a mixed solution. The water outlet area is used to transmit the mixed solution after the reaction is completed to the electrolytic cell (4). The water outlet of the first access pipe (31) is connected to the mixing area. The first remote transmission component (8) is arranged in the water outlet area. In the flow direction of the mixed solution, the first remote transmission component (8) is located between the water outlet of the first access pipe (31) and the water outlet of the second access pipe (32).

4. The chlor-alkali ion membrane brine step acidification system according to claim 2, characterized in that: The first remote transmission component (8) and the first regulating valve (9) adjust the pH value of the mixed solution in the mixing tube (5) to between 5 and 7.

5. The chlor-alkali ion-exchange membrane brine step acidification system according to claim 1, characterized in that: The water inlet of the electrolytic cell (4) is further provided with a second remote transmission component (12), and the second water outlet pipe (21) is correspondingly provided with a second regulating valve (13) connected in series with the second remote transmission component (12). The second regulating valve (13) is configured to be able to adjust the flow rate of the light brine according to the flow rate of the mixed solution monitored by the second remote transmission component (12), and then adjust the mixing ratio of the refined brine and the light brine.

6. The chlor-alkali ion-exchange membrane brine step acidification system according to claim 5, characterized in that: The mixing ratio of the refined brine and the light brine is 4:1-6:

1.

7. The chlor-alkali ion-exchange membrane brine step acidification system according to claim 5, characterized in that: The second water outlet pipe (21) is further provided with a pressurizing assembly (6) located between the second regulating valve (13) and the salt water tank (2), so that the first water outlet pipe (14) can transport the refined salt water by self-pressure while the salt water is transported through the pressurizing assembly (6) and the second regulating valve (13).

8. The chlor-alkali ion-exchange membrane brine step acidification system according to claim 2, characterized in that: A third remote transmission component (10) is further provided at the water outlet of the electrolytic cell (4); a third regulating valve (11) connected in series with the third remote transmission component (10) is correspondingly provided on the second access pipe (32); the third remote transmission component (10) is used to monitor the pH value of the salt water flowing out of the electrolytic cell (4); the third regulating valve (11) is configured to adjust the flow rate of the dilute hydrochloric acid in the second access pipe (32) according to the pH value, thereby adjusting the pH value of the mixed solution entering the electrolytic cell (4).

9. The chlor-alkali ion-exchange membrane brine step acidification system according to claim 8, characterized in that: The water outlet of the electrolytic cell (4) is connected to the salt water tank (2) so that the salt water after electrolysis by the electrolytic cell (4) is stored in the salt water tank (2).

10. The chlor-alkali ion-exchange membrane brine step acidification system according to claim 8, characterized in that: The third remote transmission component (10) and the third regulating valve (11) adjust the pH value of the mixed solution entering the electrolytic cell (4) to between 2.5 and 3.

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