A multi-point monitoring and interlocking switching system for brine parameters in denitrification units

Abstract

This utility model discloses a multi-point monitoring and interlocking switching system for brine parameters in a denitrification unit, relating to the field of denitrification equipment technology. It includes a brine tank, a brine booster pump, a primary heat exchanger, a secondary heat exchanger, an activated carbon filter, a security filter, a brine buffer tank, a high-pressure pump, and a nanofiltration membrane device connected in series. It also includes a static mixer, a water distribution tank, and a cleaning device. This utility model features fully automated monitoring and interlocking control, reducing manual intervention and avoiding frequent system shutdowns. The static mixer ensures thorough mixing of hydrochloric acid and sodium sulfite with the brine, stabilizing brine parameters, preventing monitoring fluctuations, and ensuring stable operation of the pretreatment unit. Simultaneously, it provides multi-point monitoring and recovers substandard brine, guiding it to the water distribution tank for secondary adjustment. After reaching the required standard, the brine is returned for reuse, avoiding waste of brine resources, protecting the nanofiltration membrane device, and extending its service life.

Description

Technical Field

[0001] This utility model relates to the field of denitrification equipment technology, specifically to a multi-point monitoring and interlocking switching system for the saline water index of a denitrification device. Background Technology

[0002] Membrane denitrification has become one of the mainstream technologies for denitrification of brine due to its advantages such as not requiring the addition of chemical reagents and having no secondary pollution. For example, the brine membrane denitrification system disclosed in the prior art CN215947029U achieves denitrification of brine through the combination of a pretreatment device, a membrane separation device and a cryogenic denitrification device, solving the toxic side effects and environmental problems of the traditional barium chloride method. However, existing membrane denitrification systems still have many shortcomings in actual operation.

[0003] In normal production, the removal of free chlorine by sodium sulfite is a redox reaction. The reaction can be completed instantaneously under alkaline conditions. However, under acidic conditions, sodium sulfite is extremely unstable and easily produces sulfurous acid, releasing sulfur dioxide. Therefore, when hydrochloric acid and sodium sulfite are added to the system, an acidic environment is instantly formed near the inlet, while other pipeline spaces remain alkaline. In the acidic environment, the sodium sulfite reaction is slow and uneven, while in the alkaline environment, the sodium sulfite reacts rapidly, causing significant fluctuations in the indicators detected by the subsequent pH and ORP online monitoring instruments. This seriously affects the stable operation of the brine pretreatment unit.

[0004] If the brine level in the brine buffer tank fails to meet the required standards, and the system lacks interlocking shutdown and switching devices, the substandard brine will enter the membrane filtration unit. In this case, the membrane filtration unit must be shut down, cleaned, and the substandard brine in the intermediate tank drained before the qualified brine can be introduced. This not only causes a serious waste of brine resources but also leads to frequent system shutdowns, posing a serious threat to the stable operation of the membrane filtration unit.

[0005] After the membrane filtration unit is shut down, the membrane device is manually cleaned. If the device is not cleaned thoroughly, some brine will remain in the membrane filtration device. As the shutdown time increases, the fluid flow rate and temperature in the membrane tube decrease, and sodium chloride crystallizes out small crystal particles in the brine, which block the membrane pores. As the crystallization time changes, the small crystal particles continue to grow, eventually forming granular sodium chloride solids. This will cause the nanofiltration membrane pores to enlarge rapidly or even tear, causing irreversible damage to the nanofiltration membrane. Utility Model Content

[0006] The purpose of this invention is to provide a multi-point monitoring and interlocking switching system for the brine index of a denitrification unit, which aims to solve the problems of frequent system shutdowns and nanofiltration membrane damage in the above-mentioned background technology.

[0007] To achieve the above objectives, this utility model adopts the following technical solution: a multi-point monitoring and interlocking switching system for brine indicators in a denitrification unit, comprising a brine tank, a brine booster pump, a primary heat exchanger, a secondary heat exchanger, an activated carbon filter, a security filter, a brine buffer tank, a high-pressure pump, and a nanofiltration membrane device connected in series. The inlet of the brine tank is used to connect to a dechlorination brine pipeline, and the nitrate-rich brine outlet of the nanofiltration membrane device is used to connect to a refrigerated denitrification unit. The system also includes a static mixer, a water distribution tank, and a cleaning device. The static mixer is installed on the pipeline connecting the brine booster pump and the primary heat exchanger. The static mixer is connected to the outlet of the brine booster pump, and a first hydrochloric acid pipeline and a first sodium sulfite pipeline are sequentially installed on the pipeline. A first regulating valve is installed on both the first hydrochloric acid pipeline and the first sodium sulfite pipeline. A first ORP meter and a first pH meter are installed on the pipeline connecting the static mixer and the primary heat exchanger. The activated carbon filter and the security filter are connected in series. A second ORP meter, a second pH meter, and a start-up shut-off valve are sequentially installed on the pipeline connected to the security filter. A third ORP meter, a third pH meter, and a start-up shut-off valve are sequentially installed on the pipeline connected to the high-pressure pump and the nanofiltration membrane device. A cleaning device is connected to the nanofiltration membrane device. The pipelines connecting the activated carbon filter and the security filter, and the pipelines connecting the high-pressure pump and the nanofiltration membrane device, are all connected to the water distribution tank via substandard brine pipelines. Automatic switching valves are installed on the substandard brine pipelines. A fourth ORP meter and a fourth pH meter are installed on the water distribution tank. A second hydrochloric acid pipeline and a second sodium sulfite pipeline are connected to the top of the water distribution tank. A second regulating valve is installed on the second hydrochloric acid pipeline and the second sodium sulfite pipeline. The outlet of the water distribution tank is connected to a dilute brine buffer tank. The first hydrochloric acid pipeline and the second hydrochloric acid pipeline are connected to a hydrochloric acid storage tank. The first sodium sulfite pipeline and the second sodium sulfite pipeline are connected to a sodium sulfite storage tank.

[0008] Furthermore, the cleaning device includes a cleaning liquid tank, a circulating pump, and a cleaning liquid filter. The outlet of the cleaning liquid tank is connected to the inlet of the cleaning liquid filter, the outlet of the cleaning liquid filter is connected to the inlet of the circulating pump, the outlet of the circulating pump is connected to the liquid inlet of the nanofiltration membrane device, and the liquid outlet of the nanofiltration membrane device is connected to the inlet of the cleaning liquid tank.

[0009] Furthermore, the lean nitrate outlet of the nanofiltration membrane device is connected to the cold source inlet of the primary heat exchanger, the cold source outlet of the primary heat exchanger is connected to the primary brine tank, the cold source inlet of the secondary heat exchanger is connected to the first circulating water supply line, and the cold source outlet of the secondary heat exchanger is connected to the first circulating return water line.

[0010] This utility model has the following beneficial effects: This invention provides a multi-point monitoring and interlocking switching system for denitrification equipment's brine indicators. It features fully automated monitoring and interlocking control, reducing manual intervention and preventing frequent system shutdowns. A static mixer ensures thorough mixing of hydrochloric acid and sodium sulfite with the brine, stabilizing the brine indicators, preventing monitoring fluctuations, and guaranteeing stable operation of the pretreatment unit. Simultaneously, multi-point monitoring enables the recovery of substandard brine. The interlocking switching system guides substandard brine into a distribution tank for secondary adjustment; once it meets standards, it is returned for reuse, preventing direct waste of brine resources, protecting the nanofiltration membrane device, and extending its service life. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the overall structure of this utility model; in the figure: 1. Saltwater tank; 2. Saltwater booster pump; 3. Primary heat exchanger; 4. Secondary heat exchanger; 5. Activated carbon filter; 6. Security filter; 7. Saltwater buffer tank; 8. High-pressure pump; 9. Nanofiltration membrane device; 10. Static mixer; 11. Water distribution tank; 12. Cleaning device; 13. First hydrochloric acid pipeline; 14. First sodium sulfite pipeline; 15. First regulating valve; 16. First ORP meter; 17. First pH meter; 18. Second ORP meter; 19. Second pH meter; 20. Third ORP meter; 21. Third pH meter; 22. Start-up shut-off valve; 23. Fourth ORP meter; 24. Fourth pH meter; 25. Second hydrochloric acid pipeline; 26. Second sodium sulfite pipeline; 27. Second regulating valve; 28. Automatic switching valve. Detailed Implementation

[0012] like Figure 1 As shown, a multi-point monitoring and interlocking switching system for brine indicators in a denitrification unit is designed to ensure that the brine entering the refrigerated denitrification unit meets the standards through multi-point indicator monitoring and interlocking control, while simultaneously achieving efficient treatment and recycling of substandard brine. Its components and connections are as follows: The core equipment of the system is connected in series according to the brine treatment process, and the specific connection method is as follows: The dechlorinated brine pipeline is connected to the inlet of the brine tank 1, and the outlet of the brine tank 1 is connected to the input of the brine booster pump 2 via a pipeline, thereby realizing the storage, transportation, and start-up of the raw brine. The pipeline connecting the outlet of the brine booster pump 2 to the input of the static mixer 10 is provided with a hydrochloric acid inlet and a sodium sulfite inlet, which are respectively connected to the first hydrochloric acid pipeline 13 and the first sodium sulfite pipeline 14. A first regulating valve 15 is installed on both branch pipelines for precise adjustment of the additive injection amount. The output of the static mixer 10 is connected to the heat source inlet of the first-stage heat exchanger 3 through a pipeline. The heat source outlet of the first-stage heat exchanger 3 is connected to the heat source inlet of the second-stage heat exchanger 4. After two stages of heat exchange, the brine enters the activated carbon filter 5 and the security filter 6 for deep purification.

[0013] The outlet of the security filter 6 is connected to the brine buffer tank 7. The brine buffer tank 7 is connected to the input of the high-pressure pump 8 through a pipeline. The output pipeline of the high-pressure pump 8 is connected to the inlet of the nanofiltration membrane device 9 after the third ORP meter 20, the third pH meter 21, and the start-up shut-off valve 22 are installed in sequence. The rich nitrate brine outlet of the nanofiltration membrane device 9 is connected to the refrigerated denitrification device, and the lean nitrate brine outlet is connected to the cold source inlet of the first-stage heat exchanger 3. The cold source outlet of the first-stage heat exchanger 3 is connected to the primary brine tank, thereby reducing energy consumption and realizing energy recovery and qualified lean liquid recovery.

[0014] The cold source inlet of the secondary heat exchanger 4 is connected to the first circulating water pipeline, and the cold source outlet is connected to the first circulating return water pipeline, so that heat exchange and cooling are achieved through circulating water.

[0015] The pipelines between the activated carbon filter 5 and the security filter 6, and between the high-pressure pump 8 and the nanofiltration membrane device 9, are all connected to the water distribution tank 11 through the unqualified brine pipeline. An automatic switching valve 28 is installed on the unqualified brine pipeline for diverting the unqualified brine.

[0016] The top of the water distribution tank 11 is connected to the second hydrochloric acid pipeline 25 and the second sodium sulfite pipeline 26. Both pipelines are connected to the corresponding storage tanks, and a second regulating valve 27 is installed on the pipelines. The outlet of the water distribution tank 11 is connected to the brine buffer tank 7 through a pipeline to realize the return and reuse of the treated brine.

[0017] The outlet of the cleaning solution tank of the cleaning device is connected to the inlet of the cleaning solution filter, the outlet of the cleaning solution filter is connected to the inlet of the circulating pump, the outlet of the circulating pump is connected to the branch pipeline at the inlet of the nanofiltration membrane device, and the outlet of the nanofiltration membrane device flows back to the cleaning solution tank through the branch pipeline, forming a closed-loop cleaning circuit.

[0018] On the pipeline between the static mixer 10 and the first-stage heat exchanger 3, a first ORP meter 16 and a first pH meter 17 are installed sequentially to monitor the redox potential and pH of the brine after initial adjustment. The first ORP meter 16 is interlocked with the first regulating valve 15 on the first sodium sulfite pipeline 14: when the first ORP meter 16 detects that the free chlorine index in the brine is not up to standard, the regulating valve opens and sodium sulfite is added to ensure that the redox potential of the brine is stable within the set range. The first pH meter 17 is interlocked with the first regulating valve 15 on the first hydrochloric acid pipeline 13: when the first pH measurement value is higher than the set range, the valve opens and the amount of hydrochloric acid injected is increased to adjust the acidity.

[0019] A second ORP meter 18 and a second pH meter 19 are installed on the pipeline between the activated carbon filter 5 and the security filter 6 to monitor the core indicators of the purified brine.

[0020] A third ORP meter 20 and a third pH meter 21 are installed on the pipeline between the high-pressure pump 8 and the nanofiltration membrane device 9 as the final indicator test before entering the nanofiltration membrane.

[0021] The fourth ORP meter 23 and the fourth pH meter 24 are installed inside the water distribution tank 11 to monitor the index status of the unqualified brine after adjustment in real time. The fourth ORP meter 23 is interlocked with the second regulating valve 27 on the second sodium sulfite pipeline 26, and the fourth pH meter 24 is interlocked with the second regulating valve 27 on the second hydrochloric acid pipeline 25. The control logic is the same as above to ensure that the index of the unqualified brine in the water distribution tank meets the reflux requirements after adjustment.

[0022] The start-stop valve 22 on the pipeline between the second ORP meter 18 and the second pH meter 19 and the activated carbon filter 5 and the security filter 6 is interlocked. The start-stop valve 22 on the pipeline between the third ORP meter 20 and the third pH meter 21 and the outlet pipeline of the high-pressure pump 8 is also interlocked. When the test index exceeds the set threshold, the start-stop valve 22 automatically closes, and at the same time, the corresponding unqualified brine pipeline automatic switching valve 28 opens to introduce the unqualified brine into the water distribution tank 11. When the index meets the standard, the start-stop valve 22 opens, and the brine normally enters the nanofiltration membrane device 9.

[0023] The specific operation process of this utility model is as follows: Normal processing procedure: The dechlorinated brine enters the brine tank 1 for storage, and after being pressurized by the brine booster pump 2, it is transported to the front end of the static mixer 10. At the same time, the first hydrochloric acid pipeline 13 and the first sodium sulfite pipeline 14 inject hydrochloric acid and sodium sulfite in a set ratio, which are fully mixed with the brine in the static mixer 10 to adjust the pH and ORP values.

[0024] The adjusted brine is cooled by passing through a primary heat exchanger 3 and a secondary heat exchanger 4 in sequence. It then enters an activated carbon filter 5 to adsorb organic matter and some impurities, and finally passes through a security filter 6 to remove tiny particles, ensuring the cleanliness of the brine.

[0025] The purified brine enters the brine buffer tank 7 for temporary storage. After being pressurized by the high-pressure pump 8, it is tested by the third ORP meter 20 and the third pH meter 21. If the indicators meet the standards, the shut-off valve 22 is activated and the brine enters the nanofiltration membrane device 9 to separate the nitrate-rich brine and the nitrate-poor brine. The nitrate-rich brine is sent to the cryogenic denitrification device, and the nitrate-poor brine is recovered to the primary brine tank.

[0026] Unqualified brine treatment process: When the second ORP meter 18 and the second pH meter 19 detect that the brine index at the outlet of the activated carbon filter 5 is unqualified, the shut-off valve 22 is activated to close, and the corresponding unqualified brine pipeline automatic switching valve 28 is automatically opened to introduce the unqualified brine into the water distribution tank 11.

[0027] When the third ORP meter 20 and the third pH meter 21 detect that the brine index at the outlet of the high-pressure pump 8 is not up to standard, the shut-off valve 22 is activated to close, and at the same time the corresponding automatic switching valve 28 for the unqualified brine pipeline opens, allowing the brine to flow into the water distribution tank 11.

[0028] The substandard brine in the water distribution tank 11 is monitored in real time by the fourth ORP meter 23 and the fourth pH meter 24. Additives are injected through the second hydrochloric acid pipeline 25 and the second sodium sulfite pipeline 26 for secondary adjustment. Once the indicators meet the standards, the brine is returned to the dilute brine buffer tank 7 through the outlet and re-enters the subsequent treatment process. Nanofiltration membrane cleaning process: The start-stop valve 22 is interlocked with the high-pressure pump 8. When the start-stop valve 22 is closed, the high-pressure pump 8 stops, the membrane filtration unit automatically stops, and the cleaning device starts. The cleaning solution in the cleaning solution tank is filtered by the cleaning solution filter and then pressurized and transported to the nanofiltration membrane device by the circulating pump to rinse the nanofiltration membrane. The waste liquid after cleaning is returned to the cleaning solution tank, forming a closed-loop circulation cleaning process. The cleaning device automatically stops when the online pH detection value in the cleaning device is greater than 6.5, completing the automatic cleaning of the nanofiltration membrane.

Claims

1. A multi-point monitoring and interlocking switching system for brine parameters in a denitrification unit, comprising a brine tank (1), a brine booster pump (2), a primary heat exchanger (3), a secondary heat exchanger (4), an activated carbon filter (5), a security filter (6), a brine buffer tank (7), a high-pressure pump (8), and a nanofiltration membrane device (9) connected in series, wherein the inlet of the brine tank (1) is used to connect to a dechlorination brine pipeline, and the nitrate-rich brine outlet of the nanofiltration membrane device (9) is used to connect to a refrigerated denitrification unit, characterized in that: It also includes a static mixer (10), a water distribution tank (11), and a cleaning device (12). The static mixer (10) is installed on the pipeline connecting the brine booster pump (2) and the first-stage heat exchanger (3). The static mixer (10) is connected to the outlet of the brine booster pump (2), and a first hydrochloric acid pipeline (13) and a first sodium sulfite pipeline (14) are sequentially installed on the pipeline. A first regulating valve (15) is installed on both the first hydrochloric acid pipeline (13) and the first sodium sulfite pipeline (14). A first ORP meter (16) and a first pH meter (17) are installed on the pipeline connecting the static mixer (10) and the first-stage heat exchanger (3). A second ORP meter (18), a second pH meter (19), and a start-up shut-off valve (22) are installed sequentially on the pipeline connecting the activated carbon filter (5) and the security filter (6). A third ORP meter (20), a third pH meter (21), and a start-up shut-off valve (22) are installed sequentially on the pipeline connecting the high-pressure pump (8) and the nanofiltration membrane device (9). A cleaning device (12) is connected to the nanofiltration membrane device (9). The pipeline connecting the activated carbon filter (5) and the security filter (6) and the pipeline connecting the high-pressure pump (8) and the nanofiltration membrane device (9) are all connected to the water distribution tank (11) through a substandard brine pipeline. An automatic switching valve (28) is installed on the substandard brine pipeline. A fourth ORP meter (23) and a fourth pH meter (24) are installed on the water distribution tank (11). (11) The top is connected to a second hydrochloric acid pipeline (25) and a second sodium sulfite pipeline (26). A second regulating valve (27) is provided on the second hydrochloric acid pipeline (25) and the second sodium sulfite pipeline (26). The outlet of the water distribution tank (11) is connected to the brine buffer tank (7). The first hydrochloric acid pipeline (13) and the second hydrochloric acid pipeline (25) are connected to a hydrochloric acid storage tank. The first sodium sulfite pipeline (14) and the second sodium sulfite pipeline (26) are connected to a sodium sulfite storage tank.

2. The system according to claim 1, wherein the system is characterized in that: The cleaning device (12) includes a cleaning liquid tank, a circulating pump and a cleaning liquid filter. The outlet of the cleaning liquid tank is connected to the inlet of the cleaning liquid filter, the outlet of the cleaning liquid filter is connected to the inlet of the circulating pump, the outlet of the circulating pump is connected to the liquid inlet of the nanofiltration membrane device, and the liquid outlet of the nanofiltration membrane device is connected to the inlet of the cleaning liquid tank.

3. The system according to claim 1, wherein the system further comprises a plurality of sensors for monitoring the salt concentration of the desulfurization device fresh water. The outlet of the nanofiltration membrane device (9) is connected to the cold source inlet of the primary heat exchanger (3), the cold source outlet of the primary heat exchanger (3) is connected to the primary brine tank, the cold source inlet of the secondary heat exchanger (4) is connected to the first circulating water pipeline, and the cold source outlet of the secondary heat exchanger (4) is connected to the first circulating return water pipeline.

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