Circulating blow-down water treatment system for thermal power plant

Abstract

The utility model provides a circulating blow-down water treatment system for a thermal power plant and belongs to the technical field of thermal power plant sewage treatment. The treatment system has the advantages of good pretreatment effect, backwashing function, good water treatment effect and long service life. The system comprises a collection tank, a granulation fluidized bed, a dense medium coagulating sedimentation device, a clean water tank, a sand filter device, a self-cleaning filter, a dechlorination device, an ultrafilter, an ultrafiltration water production tank, a reverse osmosis device and a reverse osmosis water production tank which are arranged along the sewage treatment flow sequence and are communicated through pipelines. The system is reasonable in structural layout, the sewage pretreatment effect is improved, and the operation burden of the whole system is relieved; the system is provided with backwashing and contact dechlorination, the sewage treatment effect is good, and the service life of the system is long.

Description

Technical Field

[0001] This utility model belongs to the field of wastewater treatment technology in thermal power plants, and in particular relates to a circulating wastewater treatment system for thermal power plants. Background Technology

[0002] Currently, the sludge produced in the high-density tanks of the pretreatment unit in the wastewater treatment process of thermal power plants faces challenges in resource utilization. High-density tanks without added weighting media have poor clarification effects, resulting in prolonged wastewater retention time and requiring a larger floor area, thus increasing space costs and resource consumption.

[0003] Reverse osmosis membranes are a highly efficient water treatment technology widely used in seawater desalination, industrial pure water production, and drinking water purification. However, with the widespread application of reverse osmosis technology, membrane fouling has gradually become one of the key factors limiting its development. Membrane fouling not only affects membrane performance and shortens its lifespan, but can also lead to reduced water production, deteriorated water quality, and increased operating costs.

[0004] Excessive TOC in reverse osmosis membranes is usually related to high organic matter content in the feed water. During reverse osmosis, most of the feed water is converted into clean product water, while organic matter and other contaminants are concentrated in the remaining concentrate. If the organic matter content in the feed water is high, the concentration of organic matter in the concentrate will also increase accordingly, leading to excessive TOC.

[0005] Existing technologies for controlling free chlorine concentration in the feed water of reverse osmosis (RO) units have significant shortcomings. Although dechlorinators and free chlorine analyzers are installed, they cannot effectively control and accurately identify the free chlorine concentration. This results in frequent oxidation of the RO membrane by residual free chlorine in the wastewater, severely affecting the stable operation and service life of the RO unit. Furthermore, existing technologies that monitor the oxidation level of the RO feed water using ORP (Oxidation Rate of Reverse Osmosis) cannot effectively identify situations where free chlorine levels exceed the standard, leading to misjudgments and introducing more risks and uncertainties into wastewater treatment. Utility Model Content

[0006] To address the problems existing in the background technology, this utility model provides a circulating wastewater treatment system for thermal power plants. This system has good pretreatment effect, backwashing function, good water treatment effect, and long service life.

[0007] The technical solution adopted by this utility model to solve its technical problem is: a circulating wastewater treatment system for a thermal power plant, comprising a collection tank, a granulation fluidized bed, a heavy media coagulation and sedimentation device, a clear water tank, a sand filter, a self-cleaning filter, a dechlorinator, an ultrafiltration device, an ultrafiltration product water tank, a reverse osmosis device, and a reverse osmosis product water tank, arranged sequentially along the wastewater treatment flow and connected by pipelines. The outlet of the collection tank is connected to the inlet of the granulation fluidized bed through a pipeline, and the outlet of the granulation fluidized bed is connected to the inlet of the heavy media flocculation and sedimentation device through a pipeline. The outlet of the media flocculation sedimentation device is connected to the clear water tank. The outlet of the clear water tank is connected to the inlet of the sand filter through a pipeline. The outlet of the sand filter is connected to the inlet of the self-cleaning filter through a pipeline. The outlet of the self-cleaning filter is connected to the inlet of the dechlorinator through a pipeline. The outlet of the dechlorinator is connected to the inlet of the ultrafiltration device through a pipeline. The outlet of the ultrafiltration device is connected to the ultrafiltration product water tank. The outlet of the ultrafiltration product water tank is connected to the inlet of the reverse osmosis device through a pipeline. The outlet of the reverse osmosis device is connected to the reverse osmosis product water tank.

[0008] The circulating wastewater treatment system of the thermal power plant also includes a crystal collection tank, which is connected to the crystal discharge outlet of the granulation fluidized bed.

[0009] The circulating wastewater treatment system of the thermal power plant also includes a sludge thickening tank and a dewatering machine. The inlet of the sludge thickening tank is connected to the sludge outlet of the heavy media coagulation and sedimentation device, and the outlet of the sludge thickening tank is connected to the dewatering machine.

[0010] The power plant's circulating wastewater treatment system also includes an ozone catalytic oxidation reactor, which is located between the sand filter and the self-cleaning filter.

[0011] The circulating wastewater treatment system of the thermal power plant also includes a backwash collection tank. The sand filter, self-cleaning filter and ultrafiltration device are all equipped with backwashing function. The backwash discharge ports of the sand filter, self-cleaning filter and ultrafiltration device are all connected to the inlet of the backwash collection tank through pipelines. The outlet of the backwash collection tank is connected to the collection tank.

[0012] The circulating wastewater treatment system of the thermal power plant also includes a free chlorine analyzer, which is installed on the pipeline connecting the ultrafiltration permeate tank and the reverse osmosis unit.

[0013] The granulation fluidized bed includes a reaction tank, an inlet pipe, a dosing pipe, a water distribution plate, a guide pipe, a seed crystal delivery pipe, a drain pipe, and multiple support rods. The axis of the reaction tank is arranged vertically, and the bottom of the reaction tank is set into a cone shape with the tip pointing downwards. A conveying pipe is connected to the tip of the bottom of the reaction tank. The water distribution plate is set at the lower part of the cylindrical tank body of the reaction tank. One end of the inlet pipe is connected to the water distribution plate and the other end extends out of the reaction tank. One end of the dosing pipe is connected to the water distribution plate and the other end extends out of the reaction tank and connects to an external reagent storage tank. The guide pipe is suspended and fixed inside the reaction tank by multiple support rods and is coaxially suspended above the water distribution plate. One end of the seed crystal delivery pipe is connected to the cavity of the guide pipe and the other end extends out to the outside of the reaction tank and connects to the seed crystal storage tank. An overflow trough is set at the upper inner side of the reaction tank. The overflow trough protrudes out of the outer wall of the reaction tank, and a drain pipe is set at the bottom of the overflow trough.

[0014] The grain collection pool includes a collection tank and a separation plate. The separation plate is fixedly arranged in the collection tank at an inclined position. The separation plate is bent, and the bending point of the separation plate points to the bottom of the collection tank. The bending point of the separation plate is far away from the water inlet of the collection tank. The outlet of the conveying pipe is inserted into the collection tank and located above the separation plate. A conveying pump is fixedly installed on the body of the conveying pipe.

[0015] The heavy media coagulation sedimentation device includes a sedimentation tank and a mixing tank. The mixing tank is raised and positioned at the center of the sedimentation tank in a fixed manner. The sedimentation tank is divided into four equal-capacity storage tanks, which surround the mixing tank. Discharge pipes are installed at the bottom of the four walls of the mixing tank, with the outlet of each discharge pipe aligned with each storage tank.

[0016] The heavy media coagulation and sedimentation device also includes an agitator. A beam frame is installed on the top of the mixing tank. The agitator is rotatably suspended below the beam frame and placed inside the mixing tank. A drive motor for driving the agitator to rotate is fixedly installed on the top surface of the beam frame. The drive shaft of the drive motor passes through the beam frame and is coaxially and fixedly connected to the agitator. When the drive motor runs, it drives the agitator to rotate, promoting the rapid and thorough mixing of wastewater and conditioning agent to form flocculation and sedimentation.

[0017] Multiple dosing nozzles are fixedly installed on the beam frame. Multiple regulator storage tanks are connected to the dosing nozzles through feeding pipes. Feeding pumps are installed on the feeding pipes. The feeding pumps pump the regulators and finally enter the mixing tank through the dosing nozzles.

[0018] The beneficial effects of this invention are as follows: The system features a rationally structured granulation fluidized bed and heavy media coagulation sedimentation device, which improves the pretreatment effect of wastewater and reduces the overall system's operational burden. The sand filter, self-cleaning filter, and ultrafiltration device in the system are all equipped with backwashing functions, and the control and monitoring of free chlorine are strengthened, reducing the fouling and oxidation of the reverse osmosis membrane. The system is rationally planned, and the recycling of calcium salt sludge from the circulating wastewater reduces the calcium ion concentration in the pretreated effluent, improves the clarification effect of the sedimentation tank, and reduces the sedimentation tank's footprint. The system uses contact dechlorination of wastewater while simultaneously monitoring the free chlorine content in the reverse osmosis device's influent, improving wastewater treatment efficiency and extending the system's operational lifespan. Attached Figure Description

[0019] In the attached diagram:

[0020] Figure 1 This is a flowchart of the overall operation of the system of this utility model;

[0021] Figure 2 This is a schematic diagram of the granulation fluidized bed structure of this utility model (partial outer wall removal);

[0022] Figure 3 This is a schematic diagram of the heavy media coagulation and sedimentation device of this utility model;

[0023] In the diagram: 1. Reaction tank; 2. Collection tank; 3. Delivery pipe; 4. Sedimentation tank; 5. Mixing tank; 6. Agitator; 11. Water inlet pipe; 12. Dosing pipe; 13. Water distribution tray; 14. Guide pipe; 15. Seed crystal delivery pipe; 16. Overflow tank; 17. Drain pipe; 18. Support rod; 21. Separation plate; 51. Beam frame; 52. Discharge pipe; 53. Dosing nozzle. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings. The drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.

[0025] A circulating wastewater treatment system for a thermal power plant includes a collection tank, a granulating fluidized bed, a heavy media coagulation and sedimentation device, a clear water tank, a sand filter, a self-cleaning filter, a dechlorinator, an ultrafiltration device, an ultrafiltration product water tank, a reverse osmosis device, and a reverse osmosis product water tank, arranged sequentially along the wastewater treatment flow path and connected by pipelines. The outlet of the collection tank is connected to the inlet of the granulating fluidized bed via a pipeline, and the outlet of the granulating fluidized bed is connected to the inlet of the heavy media flocculation and sedimentation device via a pipeline. The effluent from the heavy media flocculation and sedimentation device... The system connects to a clear water tank. The outlet of the clear water tank is connected to the inlet of the sand filter via a pipeline. The outlet of the sand filter is connected to the inlet of the self-cleaning filter via a pipeline. The outlet of the self-cleaning filter is connected to the inlet of the dechlorinator via a pipeline. The outlet of the dechlorinator is connected to the inlet of the ultrafiltration unit via a pipeline. The outlet of the ultrafiltration unit is connected to an ultrafiltration product water tank. The outlet of the ultrafiltration product water tank is connected to the inlet of the reverse osmosis unit via a pipeline. The outlet of the reverse osmosis unit is connected to a reverse osmosis product water tank.

[0026] The circulating wastewater treatment system of the thermal power plant also includes a grain collection tank, which is connected to the grain discharge outlet of the granulation fluidized bed and is used to collect mature large-sized grains.

[0027] The circulating wastewater treatment system of the thermal power plant also includes a sludge thickening tank and a dewatering machine. The inlet of the sludge thickening tank is connected to the sludge outlet of the heavy media coagulation sedimentation device, and the outlet of the sludge thickening tank is connected to the dewatering machine for thickening and dewatering the sludge discharged from the sedimentation tank.

[0028] The power plant's circulating wastewater treatment system also includes an ozone catalytic oxidation reactor, which is located between the sand filter and the self-cleaning filter.

[0029] The circulating wastewater treatment system of the thermal power plant also includes a backwash collection tank. The sand filter, self-cleaning filter and ultrafiltration device are all equipped with backwashing function. The backwash discharge ports of the sand filter, self-cleaning filter and ultrafiltration device are all connected to the inlet of the backwash collection tank through pipelines. The outlet of the backwash collection tank is connected to the collection tank. The backwash water generated by backwashing is circulated to the collection tank to participate in wastewater treatment again.

[0030] The circulating wastewater treatment system of the thermal power plant also includes a free chlorine analyzer. The free chlorine analyzer is installed on the pipeline connecting the ultrafiltration permeate tank and the reverse osmosis unit to detect and analyze the wastewater. The free chlorine analyzer is a spectrophotometric free chlorine detector. The detector's signal output is connected to the control module, and the reverse osmosis unit is triggered to shut down based on the detection results.

[0031] The dechlorinator is filled with either calcium sulfite or activated carbon filter media.

[0032] The reverse osmosis unit includes two stages of reverse osmosis. The permeate from the first stage of reverse osmosis enters the second stage of reverse osmosis for secondary desalination, and the concentrate from the second stage of reverse osmosis is returned to the ultrafiltration permeate tank.

[0033] The granulation fluidized bed includes a reaction tank 1, an inlet pipe 11, a dosing pipe 12, a water distribution plate 13, a guide pipe 14, a seed crystal delivery pipe 15, a drain pipe 17, and multiple support rods 18. The axis of the reaction tank 1 is arranged vertically, and the bottom of the reaction tank 1 is set into a cone shape with the tip pointing downwards. A conveying pipe 3 is connected to the tip of the bottom of the reaction tank 1. The water distribution plate 13 is set in the lower part of the cylindrical tank body of the reaction tank 1, and the water distribution holes of the water distribution plate 13 are set on the upper surface. One end of the inlet pipe 11 is connected to the water distribution plate 13 and the other end extends out. The reaction tank 1 has one end of the dosing pipe 12 connected to the water distribution plate 13, and the other end extending out of the reaction tank 1 and connected to an external chemical storage tank. A water pump is installed on the inlet pipe 11 to pump wastewater into the water distribution plate 13 and then into the reaction tank 1. Each dosing pipe 12 is equipped with a chemical pump, which pumps chemical agents into the water distribution plate 13. The chemical agents and wastewater mix in the water distribution plate 13 before entering the reaction tank 1. The guide pipe 14 is suspended and fixed inside the reaction tank 1 by multiple support rods 18 and coaxially suspended on the water distribution plate 13. The inner diameter of the guide pipe 14 is larger than the outer diameter of the water distribution plate 13, and the outer diameter of the guide pipe 14 is smaller than the inner diameter of the reaction tank 1. The wastewater flushed out of the water distribution plate 13 flows from bottom to top along the guide pipe 14. One end of the seed crystal feeding pipe 15 is connected to the cavity of the guide pipe 14, and the other end extends to the outside of the reaction tank 1 and is connected to the seed crystal storage tank. The seed crystals are fed into the guide pipe 14 through the seed crystal feeding pipe 15, mix with the wastewater, and react to form crystals. The crystals move from bottom to top with the water flow flushed out of the water distribution plate 13 and are connected to the guide pipe 14. The crystals at the upper end of the flow pipe 14 fall naturally to the bottom of the reaction tank 1 under the action of gravity in the gap between the flow pipe 14 and the reaction tank 1 for collection. The collected crystals are transported to the next processing step through the conveying pipe 3. An overflow trough 16 is provided at the upper inner side of the reaction tank 1. The overflow trough 16 protrudes from the outer wall of the reaction tank 1. A drain pipe 17 is provided at the bottom of the overflow trough 16. The wastewater that has completed the crystallization process continues to fill the reaction tank 1. When the wastewater level overflows the wall of the overflow trough 16, it flows into the overflow trough 16 and is discharged from the reaction tank 1 through the drain pipe 17.

[0034] The crystal collection tank includes a collection tank 2 and a separation plate 21. The separation plate 21 is fixedly arranged in the collection tank 2 in an inclined posture. The separation plate 21 is bent, and the bending point of the separation plate 21 points to the bottom of the collection tank 2. The bending point of the separation plate 21 is far away from the water inlet of the collection tank 2. The outlet of the conveying pipe 3 is inserted into the collection tank 2 and located above the separation plate 21. A conveying pump is fixedly installed on the pipe body of the conveying pipe 3. The conveying pump conveys the mixture of sewage and crystals at the bottom of the reaction tank 1 to the collection tank 2 for separation treatment through the conveying pipe 3.

[0035] Multiple reagent storage tanks are provided, each containing the required reagents such as sodium hydroxide and sodium carbonate.

[0036] The heavy media coagulation and sedimentation device includes a sedimentation tank 4 and a mixing tank 5. The mixing tank 5 is fixedly elevated at the center of the sedimentation tank 4. The sedimentation tank 4 is divided into four equal-capacity storage tanks, which surround the mixing tank 5. Discharge pipes 52 are installed at the bottom of the four walls of the mixing tank 5. The outlet of each discharge pipe 52 is aligned with each storage tank. Each storage tank has the same capacity as the mixing tank 5. Wastewater that has completed the mixing of the conditioning agent in the mixing tank 5 is discharged into any one of the storage tanks for sedimentation. The mixed wastewater in the mixing tank 5 is discharged into a single storage tank at a time.

[0037] The heavy media coagulation and sedimentation device also includes a stirrer 6. A beam frame 51 is provided on the top of the mixing tank 5. The stirrer 6 is rotatably suspended below the beam frame 51 and placed inside the mixing tank 5. A drive motor for driving the stirrer 6 to rotate is fixedly installed on the top surface of the beam frame 51. The drive shaft of the drive motor passes through the beam frame 51 and is coaxially and fixedly connected to the stirrer 6. When the drive motor runs, it drives the stirrer 6 to rotate, promoting the rapid and thorough mixing of wastewater and conditioning agent to form flocculation and sedimentation.

[0038] Multiple dosing nozzles 53 are fixedly installed on the beam frame 51. Multiple regulator storage tanks are connected to the dosing nozzles 53 through feeding pipes. A feeding pump is installed on the feeding pipe. The feeding pump pumps the regulator and finally enters the mixing tank 5 through the dosing nozzles 53.

[0039] Multiple regulator storage tanks are provided, each containing heavy medium agents, coagulants, coagulant aids, and other required regulators.

[0040] Working principle: Wastewater collected in the collection tank is fed into the granulation fluidized bed for treatment. The resulting crystals are transported into the crystal collection tank. The remaining wastewater enters the heavy media coagulation sedimentation device for flocculation. The sludge produced by flocculation is transported to the sludge thickening tank and finally dewatered by a dewatering machine to form solid impurities. The remaining wastewater after flocculation flows through the clear water tank for dilution and then flows into the sand filter for filtration. The filtered wastewater flows through the self-cleaning filter for particulate matter removal. The wastewater after particulate matter removal enters the ultrafiltration device for ultrafiltration. The ultrafiltration wastewater enters the ultrafiltration permeate tank for collection. The wastewater collected in the ultrafiltration permeate tank is analyzed by a free chlorine analyzer. The wastewater after analysis enters the reverse osmosis device for reverse osmosis and finally flows into the reverse osmosis permeate tank for collection, thus completing the treatment process.

[0041] When the granulation fluidized bed is in operation, the sewage is pumped into the inlet pipe 11 and flows through the water distribution plate 13 into the reaction tank 1. The reagent is added into the water distribution plate 13 through the dosing pipe 12 and mixed with the sewage. The sewage mixed with the reagent enters the reaction tank 1 through the water distribution holes on the upper surface of the water distribution plate 13 and flows from bottom to top along the cavity of the guide pipe 14. The seed crystal is added into the guide pipe 14 through the seed crystal addition pipe 15 and fully mixes and reacts with the sewage to form crystals. The crystals are concentrated to the bottom of the reaction tank 1 under the action of gravity. The mixture of concentrated crystals and sewage is transported into the collection tank 2 through the conveying pipe 3 for solid-liquid separation treatment. The crystals remain on the separation plate 21, and the sewage is discharged from the sewage discharge pipe at the bottom of the collection tank 2 for subsequent treatment.

[0042] Wastewater that has undergone crystallization in reaction tank 1 flows into overflow tank 16 at the top of reaction tank 1 and is discharged from reaction tank 1 through drain pipe 17 for further treatment.

[0043] When the heavy media coagulation and sedimentation device is in operation, sewage is injected into the mixing tank 5, and the regulator is added through the dosing nozzle 53. The drive motor drives the agitator 6 to rotate, promoting the rapid and thorough mixing of the regulator and sewage. The thoroughly mixed sewage is discharged into any storage tank through any discharge pipe 52 for static sedimentation.

[0044] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A circulating wastewater treatment system for a thermal power plant, characterized in that: The system includes a collection tank, a granulation fluidized bed, a heavy media coagulation and sedimentation device, a clear water tank, a sand filter, a self-cleaning filter, a dechlorinator, an ultrafiltration device, an ultrafiltration product water tank, a reverse osmosis device, and a reverse osmosis product water tank, all arranged sequentially along the wastewater treatment flow and connected by pipelines. The outlet of the collection tank is connected to the inlet of the granulation fluidized bed via a pipeline, and the outlet of the granulation fluidized bed is connected to the inlet of the heavy media flocculation and sedimentation device via a pipeline. The outlet of the heavy media flocculation and sedimentation device is connected to the clear water tank. The outlet of the clear water tank is connected to the inlet of the sand filter via a pipeline. The outlet of the sand filter is connected to the inlet of the self-cleaning filter via a pipeline. The outlet of the self-cleaning filter is connected to the inlet of the dechlorinator via a pipeline. The outlet of the dechlorinator is connected to the inlet of the ultrafiltration unit via a pipeline. The outlet of the ultrafiltration unit is connected to the ultrafiltration product water tank. The outlet of the ultrafiltration product water tank is connected to the inlet of the reverse osmosis unit via a pipeline. The outlet of the reverse osmosis unit is connected to the reverse osmosis product water tank.

2. The circulating wastewater treatment system for a thermal power plant according to claim 1, characterized in that: The circulating wastewater treatment system of the thermal power plant also includes a crystal collection tank, which is connected to the crystal discharge outlet of the granulation fluidized bed.

3. The circulating wastewater treatment system for a thermal power plant according to claim 1, characterized in that: The circulating wastewater treatment system of the thermal power plant also includes a sludge thickening tank and a dewatering machine. The inlet of the sludge thickening tank is connected to the sludge outlet of the heavy media coagulation and sedimentation device, and the outlet of the sludge thickening tank is connected to the dewatering machine.

4. The circulating wastewater treatment system for a thermal power plant according to claim 1, characterized in that: The power plant's circulating wastewater treatment system also includes an ozone catalytic oxidation reactor, which is located between the sand filter and the self-cleaning filter.

5. The circulating wastewater treatment system for a thermal power plant according to claim 1, characterized in that: The circulating wastewater treatment system of the thermal power plant also includes a backwash collection tank. The sand filter, self-cleaning filter and ultrafiltration device are all equipped with backwashing function. The backwash discharge ports of the sand filter, self-cleaning filter and ultrafiltration device are all connected to the inlet of the backwash collection tank through pipelines. The outlet of the backwash collection tank is connected to the collection tank.

6. The circulating wastewater treatment system for a thermal power plant according to claim 1, characterized in that: The circulating wastewater treatment system of the thermal power plant also includes a free chlorine analyzer, which is installed on the pipeline connecting the ultrafiltration permeate tank and the reverse osmosis unit.

7. A circulating wastewater treatment system for a thermal power plant according to claim 2, characterized in that: The granulation fluidized bed includes a reaction tank (1), an inlet pipe (11), a dosing pipe (12), a water distribution plate (13), a guide pipe (14), a seed crystal feeding pipe (15), a drain pipe (17), and multiple support rods (18). The axis of the reaction tank (1) is arranged vertically. The bottom of the reaction tank (1) is set into a cone shape with the tip pointing downwards. A conveying pipe (3) is connected to the tip of the bottom of the reaction tank (1). The water distribution plate (13) is set at a lower position inside the cylindrical tank body of the reaction tank (1). One end of the inlet pipe (11) is connected to the water distribution plate (13), and the other end passes through the reaction tank (1). The dosing pipe (14) is connected to the water distribution plate (15), and the dosing pipe (16) is connected to the water distribution plate (16). 2) One end is connected to the water distribution plate (13) and the other end passes through the reaction tank (1) and is connected to the external reagent storage tank. The guide pipe (14) is suspended and fixed in the reaction tank (1) by multiple support rods (18) and is coaxially suspended above the water distribution plate (13). One end of the seed crystal delivery pipe (15) is connected to the cavity of the guide pipe (14) and the other end passes through to the outside of the reaction tank (1) and is connected to the seed crystal storage tank. An overflow trough (16) is set at the upper inner side of the reaction tank (1). The overflow trough (16) protrudes out of the outer wall of the reaction tank (1). A drain pipe (17) is set at the bottom of the overflow trough (16). The grain collection pool includes a collection tank (2) and a separation plate (21). The separation plate (21) is fixedly arranged in the collection tank (2) in an inclined posture. The separation plate (21) is bent. The bending point of the separation plate (21) points to the bottom of the collection tank (2). The bending point of the separation plate (21) is far away from the water inlet of the collection tank (2). The outlet of the conveying pipe (3) is inserted into the collection tank (2) and located above the separation plate (21). A conveying pump is fixedly installed on the pipe body of the conveying pipe (3).

8. A circulating wastewater treatment system for a thermal power plant according to claim 3, characterized in that: The heavy media coagulation sedimentation device includes a sedimentation tank (4) and a mixing tank (5). The mixing tank (5) is raised and set in the center of the sedimentation tank (4) in a fixed manner. The sedimentation tank (4) is divided into four storage tanks of equal capacity, which surround the mixing tank (5). The bottom of the four walls of the mixing tank (5) is provided with discharge pipes (52), and the outlet of each discharge pipe (52) is aligned with each storage tank.

9. A circulating wastewater treatment system for a thermal power plant according to claim 8, characterized in that: The heavy media coagulation and sedimentation device also includes a stirrer (6). A beam frame (51) is set on the top of the mixing tank (5). The stirrer (6) is rotatably suspended below the beam frame (51) and placed inside the mixing tank (5). The drive motor for driving the stirrer (6) to rotate is fixedly set on the top surface of the beam frame (51). The drive shaft of the drive motor passes through the beam frame (51) and is coaxially fixedly connected to the stirrer (6). When the drive motor runs, it drives the stirrer (6) to rotate, promoting the rapid and thorough mixing of sewage and conditioning agent to form flocculation and sedimentation.

10. A circulating wastewater treatment system for a thermal power plant according to claim 9, characterized in that: Multiple dosing nozzles (53) are fixedly installed on the beam frame (51). Multiple regulator storage tanks are connected to the dosing nozzles (53) through feeding pipes. A feeding pump is installed on the feeding pipe. The feeding pump pumps the regulator and finally enters the mixing tank (5) through the dosing nozzles (53).

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