Coal-fired power plant high-low brine advanced treatment and recycling system based on ion replacement concentration technology

Abstract

The utility model provides a coal-fired power plant high-low salt water advanced treatment and recycling system based on an ion replacement concentration technology. Reverse washing water of a fine treatment iron and manganese removal filter, low salt water of mixed bed regeneration wastewater and high salt water of bed regeneration wastewater are fed into an industrial wastewater storage pool to be stored so as to realize quality-divided recovery; an automatic valve is arranged at an outlet of each industrial wastewater storage pool, and different dosing modes and retention time are adopted; as the industrial wastewater is finally recycled to a desulfurization system, acid and alkali do not need to be added into a final neutralization tank; low-salt water obtained after industrial wastewater treatment enters an iron and manganese removal filter for secondary removal of iron and manganese influencing operation of a desulfurization system, and is finally recycled to the desulfurization system; the mixed bed regeneration wastewater high-salinity water is discharged to a desulfurization wastewater clarification tank and treated together with desulfurization wastewater through ultrafiltration and IRCT systems, and treatment of the high-salinity water and recycling of water resources are achieved; and backwashing process treatment is regularly realized according to different water qualities.

Description

Technical Field

[0001] This utility model relates to the field of industrial wastewater, and in particular to a deep treatment and reuse system for high and low saline water in coal-fired power plants based on ion exchange concentration technology. Background Technology

[0002] Coal-fired power plants widely use high-speed mixed bed technology for boiler feedwater and condensate polishing. The anion and cation beds in boiler feedwater can be replaced by two-stage reverse osmosis, and the mixed bed can be replaced by EDI. However, high-speed mixed bed technology is still used for condensate polishing and cannot be replaced by other technologies. This is mainly due to its high operating temperature (around 55℃ for water-cooled units and around 75℃ for air-cooled units) and high operating pressure, which reverse osmosis cannot operate under. It also has a large water volume (which is why condensate polishing is called high-speed mixed bed). Using reverse osmosis and EDI would require large investments (due to the large treatment scale resulting from the large water volume), hence the use of high-speed mixed bed technology, which is irreplaceable in condensate polishing for coal-fired power plants.

[0003] The working principle of a mixed bed is mainly based on ion exchange. When water passes through the mixed bed, the cation exchange resin adsorbs cations from the water, while the anion exchange resin adsorbs anions. In this way, ionic impurities in the water are adsorbed by the resin, thus purifying the water. Over time, the resin gradually becomes saturated and can no longer adsorb ions from the water. At this point, a regeneration process is required to restore the resin's adsorption capacity. During regeneration, the acid concentration is generally controlled within the range of 4-5%, and the alkali concentration within the range of 3-4%. The acid and alkali wastewater, due to the use of large amounts of acid and alkali, has a high salt content, making it difficult to reuse in coal-fired power plants.

[0004] Mixed bed osmosis boasts numerous advantages, including high desalination efficiency, strong adaptability, ease of operation, and stability. The core issue hindering its gradual replacement is stringent environmental regulations. Power plants are opting for processes that reduce wastewater treatment, and reverse osmosis also faces environmental challenges related to waste membrane treatment and concentrate treatment. Effective comprehensive utilization of its regeneration wastewater would revitalize the technology. Furthermore, since there are currently no suitable alternatives for condensate polishing mixed bed osmosis, although the volume of its regeneration wastewater is small, coal-fired power plants lack effective disposal methods. However, if it can be recycled and reused using on-site thermal zero-emission facilities, it will improve the ecological environment to some extent.

[0005] Ion Replacement Concentration Technology (IRCT) achieves highly efficient and selective removal of ionic pollutants from desulfurization slurry. Cations (calcium, magnesium, sodium, etc.) in the slurry migrate into the chloride concentrate system under a direct current electric field, while anions (chloride, sulfate, etc.) migrate into the sodium concentrate system. Working synergistically with the slurry desulphurization system, gypsum and salts in the desulfurization slurry are discharged from the slurry system via vacuum conveyor belts and IRCT equipment, respectively. The desalinated water is recycled back into the slurry system, thus controlling the concentration of ionic components in the slurry within a low range. The ionic components discharged from the slurry system are concentrated in the chloride concentrate system, achieving a TDS concentration of over 14%. These components can be separated and utilized for resource recovery, but currently, evaporation and drying technology is still used for this purpose.

[0006] In non-zero emission coal-fired power plants, the backwash water from the fine treatment iron and manganese removal filter, the high-salt water and low-salt water from the mixed bed regeneration wastewater are mixed and then treated with conventional industrial wastewater to meet the standards before being discharged. This can basically achieve normal treatment, but it also poses certain environmental risks and wastes a large amount of low-salt water resources (a large amount of demineralized water is required for each regeneration of the mixed bed).

[0007] In zero-emission coal-fired power plants, the backwash water from the iron and manganese removal process, the high-salt water from the mixed-bed regeneration wastewater, and the low-salt water are mixed and then treated using conventional industrial wastewater methods. All of this is used as makeup water for desulfurization. However, the backwash water from the iron and manganese removal process and the high- and low-salt water from the mixed-bed regeneration process contain large amounts of iron and manganese ions, causing discoloration of the desulfurization slurry. This slightly affects desulfurization efficiency and causes discoloration of the byproduct gypsum, impacting its sales, especially during the current real estate downturn. In severe cases, the gypsum may have to be given away to the buyer. If the gypsum cannot be transported out in a timely manner, it will seriously affect the operation of the power plant.

[0008] Furthermore, because the high-salinity water entered the desulfurization system directly without any treatment, the ion content of the desulfurization slurry increased significantly, leading to insufficient dissolution of calcium and sulfur dioxide. This resulted in poorer sulfur dioxide absorption by the desulfurization system, affecting desulfurization efficiency. Additionally, the oxidation of iron and manganese ions requires oxygen, leading to incomplete sulfur oxidation and impacting gypsum quality. The large influx of ions also necessitated increased wastewater discharge from the desulfurization system, resulting in a dramatic increase in desulfurization wastewater. Utility Model Content

[0009] To address the aforementioned issues, this utility model discloses a mixed-bed regeneration deep treatment and reuse system for coal-fired power plants based on ion exchange concentration technology, which solves a series of problems that arise in the desulfurization system when the system is reused after desulfurization.

[0010] A deep treatment and reuse system for high and low saline water in a coal-fired power plant based on ion exchange concentration technology is characterized by comprising: industrial wastewater storage tank A, industrial wastewater storage tank B, and industrial wastewater storage tank C; wherein the outlets of industrial wastewater storage tank A, industrial wastewater storage tank B, and industrial wastewater storage tank C are all connected to a main outlet pipe via automatic valves, and the main outlet pipe is connected in sequence to a pH adjustment tank, a reaction tank, a flocculation tank, a clarifier, a clean water tank, and a final neutralization tank via a booster pump one; the clean water tank and the final neutralization tank are used to store the treated low and high saline water; the high saline water is fed in sequence to a desulfurization wastewater clarification tank and a desulfurization clarification water tank via a booster pump two for mixing; the mixed wastewater is fed in sequence to a desulfurization self-cleaning filter and a desulfurization ultrafiltration device via a booster pump three, and the desulfurization ultrafiltration device is connected to a desulfurization ultrafiltration water tank; the desulfurization ultrafiltration water tank is fed into a security filter via a booster pump four; and the security filter is connected to an IRCT device.

[0011] Furthermore, the security filter is connected to the IRCT unit via the #1 circulation box.

[0012] Furthermore, the low-salinity water in the purification tank is connected to the iron and manganese removal filter via a second booster pump.

[0013] Furthermore, the iron and manganese removal filter is connected to the desulfurization system.

[0014] Furthermore, industrial wastewater storage tank A, industrial wastewater storage tank B, and industrial wastewater storage tank C are used to store backwash water from the fine treatment process to remove iron and manganese, low-salt water from mixed bed regeneration, and high-salt water from mixed bed regeneration, respectively.

[0015] Furthermore, the concentrated brine from the IRCT unit enters the concentrate storage tank, which is connected to the evaporator of the drying system via a concentrate spray booster pump.

[0016] Furthermore, the treated water from the evaporator in the drying system is reused in the desulfurization system as makeup water.

[0017] Furthermore, the final neutralization tank and purification tank adopt a rotary overflow design.

[0018] Furthermore, the volume ratio of the purification pool to the final neutralization pool is 4:1.

[0019] Furthermore, the industrial wastewater storage tanks A, B, and AC are designed with corresponding anti-corrosion measures to ensure the long-term stable operation of the system.

[0020] The beneficial effects of this utility model are:

[0021] 1. Fine treatment of iron and manganese removal backwash water, high salinity mixed bed regeneration wastewater, and low salinity mixed bed regeneration wastewater for separate recovery;

[0022] 3. Before the low-salinity water is reused in the desulfurization system, an iron and manganese removal filter is installed to reduce the amount of iron and manganese entering the desulfurization system and improve the desulfurization operation effect;

[0023] 4. Coupled with the zero-emission system of coal-fired power plants, it treats and reuses high-salinity wastewater from mixed-bed regeneration, avoiding the adverse effects of high-salinity water on the desulfurization system.

[0024] 5. Particularly suitable for coal-fired power plants that have adopted ion replacement concentration technology (IRCT). Attached Figure Description

[0025] Figure 1 System diagram of this utility model. Detailed Implementation

[0026] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention. It should be noted that the terms "front", "rear", "left", "right", "up" and "down" used in the following description refer to the directions in the accompanying drawings, and the terms "inner" and "outer" refer to the directions toward or away from the geometric center of a specific component, respectively.

[0027] like Figure 1 List

[0028]

[0029] like Figure 1 As shown in this embodiment, a deep treatment and reuse system for high and low saline water in a coal-fired power plant based on ion exchange concentration technology includes an industrial wastewater storage tank A4, an industrial wastewater storage tank B5, and an industrial wastewater storage tank C6. The outlets of the industrial wastewater storage tanks A4, B5, and C6 are all connected to a main outlet pipe via automatic valves. The main outlet pipe is connected in sequence to a pH adjustment tank 9, a reaction tank 10, a flocculation tank 11, a clarifier 12, a purified water tank 14, and a final neutralization tank 13 via a booster pump. The purified water tank 14 and the final neutralization tank 13 are used for storage and treatment. After the low-salinity and high-salinity water, the low-salinity water 15 in the clean water tank 14 is connected to the iron and manganese removal filter 17 via the second lift pump; the high-salinity water 16 in the clean water tank 14 enters the desulfurization wastewater clarification tank 19 and the desulfurization clarification water tank 20 via the second lift pump; the mixed wastewater is sent to the desulfurization self-cleaning filter 21 via the third lift pump, the desulfurization self-cleaning filter 21 is connected to the desulfurization ultrafiltration device 22, the desulfurization ultrafiltration device 22 is connected to the desulfurization ultrafiltration water tank 23; the desulfurization ultrafiltration water tank 23 is connected to the security filter 24 via the fourth lift pump; the wastewater enters the IRCT device 39 for concentration treatment through the security filter 24.

[0030] The concentrated brine from the IRCT device 39 enters the concentrate storage tank 34, and the concentrate storage tank 34 is connected to the evaporator 36 of the drying system via the concentrate spray booster pump 35.1 for resource utilization.

[0031] A method for deep treatment and reuse of high and low saline water in coal-fired power plants based on ion exchange concentration technology.

[0032] Step 1: Separate recovery: The finely treated iron and manganese removal backwash water 1, the mixed bed regeneration low brine 2, and the mixed bed regeneration high brine 3 are stored in industrial wastewater storage tank A4, industrial wastewater storage tank B5, and industrial wastewater storage tank C6, respectively.

[0033] Step 2: Separate treatment: Separate treatment is carried out through low-salinity treatment and high-salinity treatment respectively.

[0034] Step 3: System operation control: Monitor the conductivity of low-salinity water using a conductivity meter to ensure separate treatment of high-salinity and low-salinity water; drain the wastewater from the industrial wastewater treatment equipment each time the water quality is switched.

[0035] The low-salinity water treatment process specifically includes: the low-salinity water entering the pH adjustment tank 9 via a booster pump 1, where acid 9.1 or alkali 9.2 is added to adjust the pH; the adjusted low-salinity water entering the reaction tank 10, where flocculant 10.1 is added to carry out flocculation reaction; the flocculated low-salinity water entering the flocculation tank 11, where coagulant aid 11.1 is added to carry out further flocculation; the flocculated low-salinity water entering the clarifier 12, where sedimentation and separation occur, the clear water entering the clean water tank 14, and the sediment being discharged through the sludge discharge port; the low-salinity water 15 in the clean water tank 14 entering the iron and manganese removal filter 17 via a booster pump 2; the low-salinity water 15 treated by the iron and manganese removal filter 17 is reused in the desulfurization system 18 as makeup water for the desulfurization system.

[0036] The treatment of high-salinity water specifically includes the following steps: High-salinity water is pumped from industrial wastewater storage tank C6 into pH adjustment tank 9 via a booster pump 1, where acid 9.1 or alkali 9.2 is added for pH adjustment; the adjusted low-salinity water then enters reaction tank 10, where flocculant 10.1 is added for flocculation; the flocculated low-salinity water then enters flocculation tank 11, where coagulant aid 11.1 is added for further flocculation; the flocculated low-salinity water then enters clarifier 12 for sedimentation and separation, with the clear water entering clean water tank 14 and the sediment being discharged through a sludge discharge port; the high-salinity water 16 in clean water tank 14 is pumped by a booster pump 2 into desulfurization wastewater clarification tank 19 and desulfurization clarifier 10. The wastewater is mixed in the clear water tank 20; the mixed wastewater is sent to the desulfurization self-cleaning filter 21 by the booster pump 3, and the wastewater after preliminary filtration enters the desulfurization ultrafiltration device 22, where it is further filtered through the ultrafiltration membrane to remove suspended solids and large molecular organic matter; the ultrafiltration wastewater enters the desulfurization ultrafiltration water tank 23 and is sent to the security filter 24 by the booster pump 4; the wastewater enters the IRCT device 39 through the security filter 24; the concentrated high-salt water is utilized by the evaporator 36 of the drying system; the high-salt water is evaporated and dried by the evaporator 36 of the drying system to realize the utilization of high-salt water; the treated clear water is reused in the desulfurization system 18 as makeup water for the desulfurization system.

[0037] The system control operation includes conductivity meter monitoring and evacuation operation. The conductivity meter monitoring involves installing a conductivity meter after the clean water tank booster pump to monitor the conductivity of low-salinity water. When the conductivity is higher than the set value by 7-15 ms / cm, it is considered high-salinity water and enters the desulfurization wastewater treatment system for treatment. When the conductivity is lower than the set value, it is considered low-salinity water and enters the iron and manganese removal filter before being reused in the desulfurization system. The evacuation operation involves emptying the industrial wastewater treatment equipment, including the pH adjustment tank 9, reaction tank 10, flocculation tank 11, clarifier 12, clean water tank 14, and final neutralization tank 13, each time the treated water quality is switched. The evacuation method is as follows: first, the bottom sediment is discharged to the sludge pit, and the upper clean water is discharged back to the original industrial wastewater storage tank.

[0038] Industrial wastewater storage tanks A4, B5, and C6 are used to store fine treatment iron and manganese removal backwash water 1, mixed bed regeneration low brine 2, and mixed bed regeneration high brine 3, respectively.

[0039] The high-salinity water flows through the desulfurization wastewater clarification tank, then sequentially through the desulfurization clarification water tank, the desulfurization self-cleaning filter, the desulfurization ultrafiltration device, the desulfurization ultrafiltration water tank, and the security filter before being fed into the IRCT device 39. The specific flow of the concentration process in the IRCT device 39 can be found in CN117695851A, and will not be elaborated here.

[0040] Corrosion protection design: The tank bodies and equipment of industrial wastewater storage tanks A4, B5, and C6 need to be designed with corresponding corrosion protection based on the water quality characteristics to ensure the long-term stable operation of the system.

[0041] Rotary overflow design: The final neutralization tank 13 and the purified water tank 14 adopt a rotary overflow design to ensure the quality of the produced water. The recommended volume ratio of the purified water tank to the final neutralization tank is 4:1 to improve treatment efficiency.

[0042] Roots blower 8: Used to provide aeration to ensure that the wastewater in reaction tank 10 and flocculation tank 11 is fully mixed.

[0043] #1 Circulation Tank 25, #1 Circulation Pump 25.1, #1 Security Filter 25.2, #1 Heat Exchanger 25.3: Used for wastewater in the circulation treatment system to ensure efficient system operation.

[0044] #2 Circulation Tank 28, #2 Circulation Pump 28.1, #2 Security Filter 28.2, #2 Heat Exchanger 28.3: Used for wastewater circulation in the system to ensure efficient system operation.

[0045] #3 Circulation Tank 26, #3 Circulation Pump 26.1, #3 Security Filter 26.2, #3 Heat Exchanger 26.3: Used for wastewater in the circulation treatment system to ensure efficient system operation.

[0046] #4 Circulation Tank 27, #4 Circulation Pump 27.1, #4 Security Filter 27.2, #4 Heat Exchanger 27.3: Used for wastewater circulation in the system to ensure efficient system operation.

[0047] #5 Circulation Tank 29, #5 Circulation Pump 29.2, #5 Security Filter 29.3, #5 Heat Exchanger 29.4: Used for wastewater in the circulation treatment system to ensure efficient system operation.

[0048] #6 Circulation Tank 30, #6 Circulation Pump 30.2, #6 Security Filter 30.3, #6 Heat Exchanger 30.4: Used for wastewater in the circulation treatment system to ensure efficient system operation.

[0049] Reducing agent dosing device 31 and reducing agent dosing pump 31.1: used to add reducing agent to the system to ensure the smooth progress of chemical reactions in the wastewater treatment process.

[0050] Acid dosing device 32 and acid dosing pump 32.1: used to add acid to the system to ensure pH adjustment during wastewater treatment.

[0051] Desalination liquid drain tank 33: Used to store desalination liquid to ensure the normal operation of the system.

[0052] Concentrate storage tank 34 and concentrate buffer tank 35: used to store concentrated high-salinity water to ensure the resource utilization of high-salinity water.

[0053] High-temperature flue gas inlet 37 and air preheater outlet flue 38: used to provide high-temperature flue gas to ensure the efficient operation of the evaporator 36 in the drying system.

[0054] This embodiment:

[0055] Based on the characteristics of the three water qualities, an automatic valve is installed at the outlet of the industrial wastewater storage tank. Different dosing methods and retention times are used (the retention time is adjusted by manually controlling the valve of the booster pump 1 or by using a frequency converter to change the treated water flow rate). This completes the treatment of industrial wastewater. Since the wastewater is ultimately reused in the desulfurization system, there is no need to add acid or alkali in the final neutralization tank. Because the backwashing and mixed bed regeneration of the fine treatment iron and manganese removal filter have long cycles (generally more than 45 days), the industrial wastewater treatment equipment (pH adjustment tank, reaction tank, flocculation tank, clarifier, clean water tank, and final neutralization tank) needs to be emptied each time the treated water quality is switched. To save on overall investment, the final neutralization tank may not have a submersible booster pump; instead, a temporary submersible booster pump is used for cleaning during its periodic treatment. The small amount of wastewater has little impact on operation. It is recommended that the volume ratio of the clean water tank to the final neutralization tank be approximately 4:1.

[0056] Drainage method: The pH adjustment tank, reaction tank, flocculation tank and clarifier are all equipped with bottom drain valves. First, the bottom sediment is drained into the sludge pit (the sludge will be transported to the sludge treatment room for centralized dewatering), and the clear water at the top is discharged back into the original industrial wastewater storage tank.

[0057] The final neutralization tank and the purified water tank adopt a rotary overflow design. A volume ratio of approximately 4:1 between the purified water tank and the final neutralization tank is recommended to improve the quality of the produced water. The final neutralization tank should be cleaned regularly using a submersible lift pump.

[0058] The water treated by the fine treatment of iron and manganese removal backwash water and mixed bed regeneration wastewater after low-salinity treatment is collectively referred to as low-salinity water. It enters the iron and manganese removal filter for secondary removal of iron and manganese that affect the operation of the desulfurization system, and is finally reused in the desulfurization system.

[0059] The high-salinity wastewater from the mixed-bed regeneration process is discharged to the desulfurization wastewater clarification tank, where it is treated together with the desulfurization wastewater through an ultrafiltration and IRCT system to achieve the treatment of high-salinity water and the reuse of water resources.

[0060] A conductivity meter is installed after the booster pump in the clean water tank to determine the salinity of the water. If the concentration exceeds a set value, it is considered high-salinity and treated using a zero-discharge system. Conversely, if the concentration is below a set value, it is filtered by an iron and manganese removal filter and reused. The conductivity value is generally set between 7 mS / cm and 15 mS / cm and can be adjusted according to the conductivity of the desulfurization slurry. A lower value is preferable when the desulfurization slurry concentration is high, and a higher value is preferable when the concentration is low.

[0061] The technical means disclosed in this utility model are not limited to the technical means disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A deep treatment and reuse system for high and low saline water in coal-fired power plants based on ion exchange concentration technology, characterized in that: The system includes three industrial wastewater storage tanks: A, B, and C. The outlets of these three tanks are connected to a main outlet pipe via automatic valves. The main outlet pipe is then connected in sequence to a pH adjustment tank, reaction tank, flocculation tank, clarifier, purified water tank, and final neutralization tank via a booster pump. The purified water tank and final neutralization tank store the treated low- and high-salinity water, respectively. The high-salinity water is then pumped in sequence to a desulfurization wastewater clarification tank and a desulfurization clarification water tank for mixing. The mixed wastewater is then pumped in sequence to a desulfurization self-cleaning filter and a desulfurization ultrafiltration device via a booster pump. The desulfurization ultrafiltration device is connected to a desulfurization ultrafiltration water tank. The desulfurization ultrafiltration water tank is then pumped into a security filter via a booster pump. Finally, the security filter is connected to an IRCT device.

2. The deep treatment and reuse system for high and low saline water in a coal-fired power plant based on ion exchange concentration technology according to claim 1, characterized in that: The security filter is connected to the IRCT device via the #1 circulation box.

3. The deep treatment and reuse system for high and low saline water in a coal-fired power plant based on ion exchange concentration technology according to claim 1, characterized in that: The low-salinity water in the purification tank is connected to the iron and manganese removal filter via a second booster pump.

4. The deep treatment and reuse system for high and low saline water in a coal-fired power plant based on ion exchange concentration technology according to claim 3, characterized in that: The iron and manganese removal filter is connected to the desulfurization system.

5. A deep treatment and reuse system for high and low saline water in a coal-fired power plant based on ion exchange concentration technology according to claim 1, characterized in that: Industrial wastewater storage tank A, industrial wastewater storage tank B, and industrial wastewater storage tank C are used to store backwash water from the fine treatment process to remove iron and manganese, low-salinity water from mixed bed regeneration, and high-salinity water from mixed bed regeneration, respectively.

6. The deep treatment and reuse system for high and low saline water in a coal-fired power plant based on ion exchange concentration technology according to claim 1, characterized in that: After concentration in the IRCT unit, the high-salt water enters the concentrate storage tank, which is connected to the evaporator of the drying system via a concentrate spray booster pump.

7. A deep treatment and reuse system for high and low saline water in a coal-fired power plant based on ion exchange concentration technology according to claim 6, characterized in that: The treated water from the evaporator in the drying system is reused in the desulfurization system as makeup water.

8. The deep treatment and reuse system for high and low saline water in a coal-fired power plant based on ion exchange concentration technology according to claim 1, characterized in that: The final neutralization tank and the purification tank adopt a rotary overflow design.

9. A deep treatment and reuse system for high and low saline water in a coal-fired power plant based on ion exchange concentration technology, as described in claim 1 or 8, characterized in that: The volume ratio of the purification pool to the final neutralization pool is 4:

1.

10. A deep treatment and reuse system for high and low saline water in a coal-fired power plant based on ion exchange concentration technology according to claim 1, characterized in that: The industrial wastewater storage tanks A, B, and AC are designed with appropriate anti-corrosion measures to ensure the long-term stable operation of the system.

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