Comprehensive wastewater deep circulation treatment water-saving system for power plant

Abstract

The utility model relates to the technical field of power plant comprehensive wastewater treatment, in particular to a power plant comprehensive wastewater deep circulation treatment water-saving system which comprises a wastewater buffer pool. A chemical crystallization granulation fluidized bed, a steel clarifier, a clean water tank, a high-efficiency fiber filter, an ultrafiltration device, an ultrafiltration water production tank, a reverse osmosis device and a reuse water tank are in fluid communication with a water outlet of the wastewater buffer tank in the water flow direction, the reverse osmosis device is provided with a first water discharge pipe and a second water production pipe, and the first water discharge pipe is connected with a desulfurization system; the second water producing pipe is connected with a recycling water tank, and the recycling water tank is connected with a recycling system through a pipeline. A softening and clarifying pretreatment mode is adopted, so that the removal rate of SS (suspended solids) reaches up to 80-90%, and the SS content of effluent is kept below 10mg / L; the removal rate of COD (chemical oxygen demand) can reach 20-30%; the hardness removal rate reaches up to 80%-90%, and the effluent hardness is kept below 20 mg / L; in addition, calcium fluoride is generated while hardness is removed, and most fluorine ions can be removed.

Description

Technical Field

[0001] The utility model relates to the technical field of comprehensive wastewater treatment in power plants, in particular to a water-saving system for deep circulation treatment of comprehensive wastewater in power plants. Background Art

[0002] At present, the comprehensive wastewater of power plants includes: RO concentrated water from chemical water workshop, yin-yang mixed bed regeneration water from chemical water workshop, ultrafiltration backwash water from chemical water workshop, circulating water sewage and fine treatment regeneration wastewater. The comprehensive wastewater of power plants has the characteristics of high salinity, high hardness and alkalinity, high active silicon content and high fluoride ion content. In addition, there are certain risks of organic pollution, microbial pollution and colloid pollution, and there is a tendency of scaling and clogging with calcium carbonate, calcium sulfate, calcium fluoride, colloidal silica and the like.

[0003] The existing environmental protection requirements for comprehensive wastewater treatment in power plants are becoming more and more stringent, such as the corresponding environmental impact assessment requirements during the construction of power plants: "All production and domestic sewage (wastewater) in the entire plant shall be reused after treatment meets the standards and shall not be discharged" and "wastewater discharge permit". In order to implement these environmental impact assessment requirements, rationally utilize water resources, increase efficiency and save energy, reduce the discharge of production and domestic sewage (wastewater), improve the economic, environmental and social benefits of enterprises, and improve the operation level of power plants, power plants urgently need to implement comprehensive wastewater deep treatment, recycling and water-saving projects. Utility Model Content

[0004] The technical problem to be solved by the utility model is to overcome the shortcomings of the prior art and provide a water-saving system for deep circulation treatment of comprehensive wastewater from a power plant. The system achieves the effect of circulating treatment of wastewater by arranging a chemical crystallization granulation fluidized bed, a steel clarifier, a clear water tank, a high-efficiency fiber filter, an ultrafiltration device, an ultrafiltration water production tank, a reverse osmosis device and a reuse water tank.

[0005] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0006] A water-saving system for deep-circulation treatment of comprehensive wastewater in a power plant comprises a wastewater buffer tank, wherein the drainage outlet of the wastewater buffer tank is fluidly connected with a chemical crystallization granulation fluidized bed, a steel clarifier, a clear water tank, a high-efficiency fiber filter, an ultrafiltration device, an ultrafiltration water production tank, a reverse osmosis device and a reuse water tank along the water flow direction, wherein the reverse osmosis device comprises a first drainage pipe and a second water production pipe, wherein the first drainage pipe is connected with a desulfurization system, and the second water production pipe is connected with a reuse water tank, and the reuse water tank is connected with a reuse system through a pipeline.

[0007] Preferably, the wastewater discharge ports of the ultrafiltration device and the high-efficiency fiber filter are connected to the wastewater buffer tank through pipelines.

[0008] Preferably, the chemical crystallization granulation fluidized bed is in the shape of a tank, and a water distribution area, a drug distribution area, a fluidization area, a granulation area, a static settling area and a first clear water area are arranged inside the tank body of the chemical crystallization granulation fluidized bed.

[0009] Preferably, the steel clarifier is provided with a second clean water zone, a separation zone and a sludge hopper in sequence from top to bottom, an inclined plate is installed in the separation zone, a sludge discharge pipe connected to the sludge hopper is provided below the steel clarifier, and the sludge discharge pipe is connected to the reclaimed water sludge system.

[0010] Preferably, a wastewater pump is provided in the wastewater buffer tank, a clean water pump is provided in the clean water tank, a lift pump is provided in the ultrafiltration water production tank, and a reuse water pump is provided in the reuse water tank. The wastewater pump, clean water pump, lift pump and reuse water pump are all connected to the overall control system.

[0011] Compared with the prior art, the beneficial effects of the utility model are:

[0012] 1. The utility model adopts a softening + clarifying pretreatment method to achieve a SS removal rate of up to 80% to 90%, and the SS content of the effluent is maintained below 10 mg / L; the COD removal rate can reach 20 to 30%; the hardness removal rate is as high as 80% to 90%, and the effluent hardness is maintained below 20 mg / L; in addition, while removing hardness, calcium fluoride is generated, which can remove most of the fluoride ions.

[0013] 2. The "softening + clarification" pretreatment device of this utility model adopts chemical crystallization granulation fluidized bed + high-efficiency clarifier. Compared with the traditional high-density sedimentation tank and mechanical accelerated clarification tank, it has many advantages such as good effluent quality, strong load impact resistance, strong adaptability to raw water, small footprint, low self-consumption of water, high sludge concentration, simple operation and convenient construction. This is especially reflected in the chemical crystallization granulation fluidized bed. The successful project case has a single set of treatment capacity of 180m 3 / h, the specification of chemical crystallization granulation fluidized bed is Φ1800mm x6650mm (diameter x height); if a high-density sedimentation tank is used, the tank size is about 11.6m x9.4mx7.9m (length x width x height).

[0014] 3. Control of UF inlet water quality: Practice has shown that when the UF inlet turbidity is controlled within 5NTU, the UF operation performance is better, the produced water turbidity is <0.1NTU, SDI <3, the transmembrane pressure difference can be controlled within TMP <0.1MPa, and the service life of the UF membrane element is ≥5 years. The utility model adopts a high-efficiency fiber filter as a control device for the ultrafiltration inlet water quality. Compared with the traditional multi-media filter, it not only has a simple structure and is easy to operate, but also can improve the filtering accuracy. After the raw water is treated by coagulation, the removal of suspended matter can reach more than 90%, and it has a significant removal effect on impurities such as bacteria, viruses, and large molecular organic matter; and the filtration speed is fast, which is 3 to 5 times that of the traditional filter; and the sewage interception capacity is large, which is 2 to 4 times that of the traditional filter; the high-efficiency fiber filter occupies a small area, and for the same amount of water produced, the area occupied by the high-efficiency fiber filter is only 1 / 3 to 1 / 5 of that of the traditional filter, which greatly saves infrastructure investment; and the cost per ton of water is low, which is 1 / 2 to 2 / 3 of that of the traditional filter, and the self-use water consumption is also relatively low, which is only 1 to 3% of the water produced.

[0015] 4. The utility model adopts the "ultrafiltration + reverse osmosis" double membrane process. The conductivity of the produced water after reverse osmosis treatment is less than 100μS / cm, which can be reused in the cooling tower water supply system to provide a circulating concentration ratio, thereby minimizing the amount of fresh water resources used by the power plant; and reused in the original chemical water desalination water production workshop as a source of boiler feed water, thereby reducing the amount of fresh water resources used by the power plant; the excellent pretreatment effect makes the recovery rate of the reverse osmosis device as high as 75%, and the amount of concentrated water produced is less than 25%, which can be completely absorbed by the desulfurization system of the power plant, realizing zero discharge of comprehensive wastewater; and ultrafiltration and reverse osmosis have mature technology and stable operation; high integration and small footprint; simple equipment and process flow, easy operation, management and maintenance; high degree of automation and wide range of applications.

[0016] 5. The utility model realizes the purpose of saving water by recycling the RO concentrated water of the chemical water workshop of the power plant, the Yin-Yang mixed bed regenerated water of the chemical water workshop, the ultrafiltration backwash water of the chemical water workshop, the circulating water sewage and the refined treatment regenerated wastewater. The above five waters are deeply treated and then recycled. At the same time, the final concentrated water volume produced achieves the good result of complete consumption of the desulfurization system of the power plant, and realizes zero discharge of comprehensive wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structural arrangement of the utility model;

[0018] Figure 2 It is a schematic diagram of the structure of a fluidized bed for chemical crystallization granulation;

[0019] Figure 3 Schematic diagram of the structure of a steel clarifier.

[0020] In the figure: 1. Wastewater buffer tank; 2. Chemical crystallization granulation fluidized bed; 3. Steel clarifier; 4. Clear water tank; 5. High-efficiency fiber filter; 6. Ultrafiltration device; 7. Ultrafiltration water production tank; 8. Reverse osmosis device; 9. Recycled water tank; 10. Water distribution area; 11. Drug distribution area; 12. Granulation area; 13. First clear water area; 14. Fluidization area; 15. Settling area; 16. Second clear water area; 17. Separation area; 18. Sludge hopper; 19. Sludge discharge pipe; 20. Inclined plate. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0022] Embodiment 1

[0023] A water-saving system for deep circulation treatment of comprehensive wastewater from a power plant, the structure of which is as follows Figure 1-Figure 3 As shown, it includes a wastewater buffer tank 1, wherein the drainage outlet of the wastewater buffer tank 1 is fluidly connected with a chemical crystallization granulation fluidized bed 2, a steel clarifier 3, a clean water tank 4, a high-efficiency fiber filter 5, an ultrafiltration device 6, an ultrafiltration water production tank 7, a reverse osmosis device 8 and a reuse water tank 9 along the water flow direction, wherein the reverse osmosis device 8 has a first drainage pipe and a second water production pipe, wherein the first drainage pipe is connected to the desulfurization system, and the second water production pipe is connected to the reuse water tank 9, and the reuse water tank 9 is connected to the reuse system through a pipeline. The chemical crystallization granulation fluidized bed 2 is in the shape of a tank, and a water distribution area 10, a drug distribution area 11, a fluidization area 14, a granulation area 12, a static sedimentation area 15 and a first clean water area 13 are arranged inside the tank body of the chemical crystallization granulation fluidized bed 2. The steel clarifier 3 is provided with a second clean water area 16, a separation area 17 and a sludge hopper 18 from top to bottom, and a sludge discharge pipe 19 connected to the sludge hopper 18 is provided below the steel clarifier 3, and the sludge discharge pipe 19 is connected to the reclaimed water sludge system. A wastewater pump is provided in the wastewater buffer tank 1, a clean water pump is provided in the clean water tank 4, a lifting pump is provided in the ultrafiltration water production tank 7, and a reuse water pump is provided in the reuse water tank 9. The wastewater pump, clean water pump, lifting pump and reuse water pump are all connected to the overall control system.

[0024] The comprehensive wastewater of the power plant includes RO concentrated water from the chemical water production workshop, yin-yang mixed bed regenerated water from the chemical water production workshop, ultrafiltration backwash water from the chemical water production workshop, circulating water sewage and fine treatment regenerated wastewater.

[0025] First, the circulating water sewage is led from the circulating water sewage pipe in the factory to the wastewater buffer tank 1 through a pipeline; the refined treated regenerated wastewater is led to the drainage ditch in the chemical water production workshop through a pipeline; the remaining water sources are collected from the drainage ditch of the chemical water production workshop to the wastewater buffer tank 1 for mixing and homogenization, and then lifted by the wastewater pump to enter the chemical crystallization granulation fluidized bed 2. The wastewater first enters the water distribution area 10 through the water inlet pipe at the bottom of the chemical crystallization granulation fluidized bed 2, and the crystal seeds and alkaline agents (sodium hydroxide, sodium carbonate) are added to the drug distribution area 11 in the chemical crystallization granulation fluidized bed 2, so that the calcium ions in the water react chemically to form calcium carbonate crystals, which are attached to the surface of the crystal seeds. With the continuous attachment of calcium carbonate, the crystals slowly grow, and finally form large particles that are precipitated and sink to the bottom of the water for discharge. The principle of the crystallization and softening treatment equipment is that water enters from the bottom of the tank, so that the seed crystal exists in a suspended state in the water. By adding NaOH and Na2CO3, the calcium ions in the water form CaCO3 and wrap around the seed crystal, slowly forming large crystal particles. When they are large enough, they are precipitated at the bottom of the tank and discharged, and the top of the tank forms the first clear water area 13. This technology does not produce by-products, and the produced CaCO3 particles can be recycled. Chemical crystallization granulation fluidized bed 2 softening technology has the advantages of high treatment efficiency, stable water effect, simple operation and management, and no by-products; and it can also remove a certain amount of silicon and phosphorus.

[0026] Then, the wastewater enters the steel clarifier 3 through the pipeline, and sodium hypochlorite, coagulant PAC, and flocculant PAM are added to significantly remove impurities such as microorganisms, silicon, hardness, fluoride ions, suspended solids, colloids, and a small amount of organic matter. The effluent from the clarifier is adjusted to pH 8-9 by sulfuric acid and then enters the subsequent clean water tank 4; the rising flow rate of the second clean water area 16 in the steel clarifier 3 is controlled to be no more than 1.2 mm / s. Since the second clean water area 16 is equipped with an inclined plate 20, the sedimentation area can be increased, so that the flocs adhere to the bottom of the inclined plate 20 during the rising process of the clean water and gradually settle down, thereby improving the mud-water separation effect. The settled sludge enters the sludge hopper 18 at the bottom of the steel clarifier 3 and is then discharged through the sludge discharge port.

[0027] The water produced by the steel clarifier 3 enters the clean water tank 4. After being lifted by the clean water pump, it passes through the high-efficiency fiber filter 5 and the ultrafiltration device 6 in turn to perform deep pretreatment on the wastewater. The treated wastewater enters the ultrafiltration water production tank 7. The lifting pump inside the ultrafiltration water production tank 7 pumps the wastewater into the reverse osmosis device 8 for desalination treatment. The treated high-quality water is stored in the reuse water tank 9. The reverse osmosis water is transported to the circulating water system as cooling tower water supplement or chemical water ultrafiltration water tank. The reverse osmosis concentrated water is transported to the desulfurization system through a pipeline for reuse.

[0028] The reverse osmosis water is recycled to the cooling tower water supply system through the recycling water pump to provide a circulating concentration ratio, and is also recycled to the original chemical water desalination water production workshop as a source of boiler feed water, reducing the power plant's use of fresh water resources. It has the advantages of mature technology and stable operation; high integration and small footprint; simple equipment and process flow, easy operation, management and maintenance; high degree of automation and wide range of applications.

[0029] In the process of the comprehensive wastewater deep treatment and recycling of the power plant, the sludge water produced by the steel clarifier 3 is transported to the regenerated water sludge system for treatment, and the crystal particles produced by the chemical crystallization granulation fluidized bed 2 are directly treated together with the limestone of the power plant or disposed of together with the sludge by the power plant.

[0030] The overall control system can implement program control over the system equipment, and use LED and keyboard as monitoring and control means to complete the collection, processing and recording of system information. It can be operated automatically, semi-automatically, manually on site, and by a microcomputer using a keyboard in the control room. Among them, the dosing of the chemical crystallization granulation fluidized bed 2 and the steel clarifier 3 can be automatically adjusted according to the inlet flow rate, the steel clarifier 3 can automatically discharge mud, the high-efficiency fiber filter 5 can realize regular backwashing operation, the inlet water and backwashing dosing of the ultrafiltration device 6 can be automatically controlled according to the flow rate, the ultrafiltration device 6 can automatically backwash regularly, the dosing of the inlet water of the reverse osmosis device 8 can be automatically controlled according to the flow rate, the reverse osmosis system is monitored according to the system pressure difference, the effluent water quality and the periodic water production, and regular automatic or semi-automatic cleaning is realized, and the liquid level of each water pump and water tank / pool is interlocked.

[0031] The wastewater discharge ports of the ultrafiltration device 6 and the high-efficiency fiber filter 5 are connected to the wastewater buffer tank 1 through pipelines.

[0032] The ultrafiltration device 6 and the high-efficiency fiber filter 5 can be automatically backwashed regularly, and the wastewater after backwashing can be discharged back into the wastewater buffer tank 1 through the pipeline for circulation treatment, thereby improving the total recovery rate of the system.

[0033] The above is only a preferred specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any changes or additions, subtractions or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the utility model should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A water-saving system for deep circulation treatment of comprehensive wastewater in a power plant, comprising a wastewater buffer tank (1), characterized in that: The drainage outlet of the wastewater buffer tank (1) is fluidly connected to a chemical crystallization granulation fluidized bed (2), a steel clarifier (3), a clean water tank (4), a high-efficiency fiber filter (5), an ultrafiltration device (6), an ultrafiltration water production tank (7), a reverse osmosis device (8) and a reuse water tank (9) along the water flow direction. The reverse osmosis device (8) has a first drainage pipe and a second water production pipe. The first drainage pipe is connected to the desulfurization system, and the second water production pipe is connected to the reuse water tank (9). The reuse water tank (9) is connected to the reuse system through a pipeline.

2. A water-saving system for deep circulation treatment of comprehensive wastewater from a power plant according to claim 1, characterized in that: The wastewater discharge ports of the ultrafiltration device (6) and the high-efficiency fiber filter (5) are connected to the wastewater buffer tank (1) via pipelines.

3. A water-saving system for deep circulation treatment of comprehensive wastewater from a power plant according to claim 1, characterized in that: The chemical crystallization granulation fluidized bed (2) is in the shape of a tank, and a water distribution area (10), a drug distribution area (11), a fluidization area (14), a granulation area (12), a static settling area (15) and a first clear water area (13) are arranged inside the tank body of the chemical crystallization granulation fluidized bed (2).

4. A water-saving system for deep circulation treatment of comprehensive wastewater from a power plant according to claim 1, characterized in that: The steel clarifier (3) is provided with a second clean water zone (16), a separation zone (17) and a sludge hopper (18) in order from top to bottom. An inclined plate (20) is installed in the separation zone (17). A sludge discharge pipe (19) connected to the sludge hopper (18) is provided below the steel clarifier (3). The sludge discharge pipe (19) is connected to the regenerated water sludge system.

5. A water-saving system for deep circulation treatment of comprehensive wastewater from a power plant according to claim 3, characterized in that: The wastewater buffer tank (1) is provided with a wastewater pump, the clean water tank (4) is provided with a clean water pump, the ultrafiltration water production tank (7) is provided with a lift pump, and the reuse water tank (9) is provided with a reuse water pump. The wastewater pump, clean water pump, lift pump and reuse water pump are all connected to a general control system.

Images