Circulating blow-down water treatment device for coal-fired power plant based on crystallization and granulation fluidized bed

Abstract

The utility model provides a circulating blow-down water treatment device based on a crystallization and granulation fluidized bed coal-fired power plant. Comprising a cooling tower pool, a multi-medium filter, a crystallization and granulation fluidized bed, a circulating blow-down water buffer pool, a high-density clarification pool, a plug flow channel, a variable-porosity filter pool, a clarification water pool, a self-cleaning filter, an ultrafiltration device, an ultrafiltration water tank, an ultraviolet sterilizer, a security filter and a reverse osmosis device which are connected in sequence. According to the scheme, by introducing induced crystallization for hardness removal and synergistic silicon removal, deep precision treatment can be performed on the circulating sewage, quality-divided recycling is realized, and gradient utilization of water resources is realized; in addition, in the treatment process, the use of chemicals polluting the environment is reduced, the entry of chlorine radicals is avoided, and the great increase of the amount of the recycled desulfurization wastewater is effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to sewage treatment technology, belongs to the field of circulating blowdown water treatment and reuse of coal-fired power plants, and particularly relates to a circulating blowdown water treatment device for coal-fired power plants based on crystallization granulation fluidized bed. BACKGROUND

[0002] Under the background of increasingly tight fresh water resources, the management and optimization of the circulating cooling water system of coal-fired power plants, as a "big water user", is particularly important. The circulating cooling water system of coal-fired power plants effectively removes the heat generated during the production process through the circulation of water, ensuring the normal operation of equipment or processes. However, with the evaporation and wind loss of water, for example, for two 350 MW units, the evaporation amount is about 957 m³ / h, and the wind loss is about 37 m³ / h, the total amount is about 994 m³ / h, and a large amount of water resources needs to be continuously supplemented. The salt in the circulating water gradually concentrates with the loss of water, and the problem of deteriorating water quality is increasingly prominent. High concentration of salt not only easily leads to the formation of scale and dirt, but also provides a material basis for microorganisms. Salt causes corrosion of equipment, and a large number of microorganisms breed, which can produce biological slime. This slime is mainly composed of microorganisms themselves, their metabolites, and suspended solids in water, and is easy to deposit on the surface of pipelines, equipment and cooling towers. The formation of biological slime can cause pipeline blockage and equipment scaling, thereby reducing the heat transfer efficiency of heat exchangers and the cooling efficiency of cooling towers, causing uneven heating of the heat exchange surface, and greatly increasing the water head loss. In addition, biological slime also isolates the effect of corrosion and scale inhibitors on the metal surface, so that the agents cannot play their due corrosion and scale inhibition efficiency, which threatens the safe operation and economic benefits of the power plant.

[0003] In order to solve these problems, coal-fired power plants usually take various measures to maintain the stability of the water quality of circulating cooling water. Among them, adding corrosion and scale inhibitors is an important means. These agents can complex with metal ions in water to prevent scale formation; at the same time, they can also form a protective film on the surface of equipment to slow down the corrosion rate; in addition, corrosion and scale inhibitors can prevent the aggregation and deposition of dirt particles through mechanisms such as electrostatic repulsion.

[0004] Coal-fired power plant circulating water systems usually use the method of impact dosing to add bactericides. That is, after a large amount of bactericide is added at one time, the agent is uniformly distributed in the entire system through the flow of circulating water. Impact dosing can quickly increase the concentration of bactericides in circulating water, thereby effectively killing microorganisms. And select bactericides with fast killing speed and high broad-spectrum, in order to prevent the development of drug resistance of microorganisms, different types of bactericides are also used alternately.

[0005] Coal-fired power plant circulating water also undergoes pH adjustment to ensure stable operation of the circulating water system and reduce equipment corrosion rates. Too high or too low pH values ​​can lead to problems such as equipment corrosion, scaling, and microbial growth.

[0006] In summary, corrosion and scale inhibitors, bactericides, and pH adjustments all introduce new ions, further increasing the salinity of the water while maintaining the stable operation of the circulating water system. Therefore, relying solely on corrosion and scale inhibitors, bactericides, and pH adjustments cannot completely solve the problems of the circulating cooling water system. As the water is continuously circulated, its concentration ratio gradually increases. Once it reaches a certain level, some wastewater must be discharged to reduce the salinity. Taking two 350MW units as an example, the wastewater discharge from the circulating water system is approximately 282 m³ / h. The treatment and reuse of circulating wastewater from coal-fired power plants is a crucial part of the cascade utilization of water resources in power plants, and salinity separation is key to the treatment and reuse of circulating wastewater.

[0007] Currently, most mainstream circulating water wastewater treatment methods employ mechanically accelerated clarifiers or high-efficiency clarifiers for softening, requiring the addition of large amounts of lime and sodium carbonate. The lime-sodium carbonate combined process system is designed as a two-stage reaction plus sedimentation and clarification treatment. The first-stage reaction is lime treatment, where lime is added to the first-stage reactor to adjust the pH of the wastewater. For zero-discharge softening treatment, the wastewater pH is raised to 10-11; specific control parameters must be determined experimentally. An online pH meter can be installed in the first-stage reactor to automatically control the lime dosage. The second-stage reaction is mainly a calcium removal system, where sodium carbonate is added to the second-stage reactor to remove calcium from the wastewater. 2+ Calcium carbonate precipitates, and the pH is eventually adjusted with hydrochloric acid. Its drawbacks are as follows:

[0008] 1. Adjusting the pH to 10-11 requires a large amount of lime. Lime mining damages the environment, and with the increasing demands of lime mining and environmental protection, the quality of lime deteriorates, the price increases, and the stability of system operation deteriorates.

[0009] 2. The large amounts of sodium carbonate and hydrochloric acid added to the water result in the presence of chloride ions. The concentrated brine is typically reused in desulfurization processes, leading to a significant increase in the ion content of the desulfurization slurry. This results in insufficient dissolution of calcium and sulfur dioxide, impairing the desulfurization system's absorption of sulfur dioxide and affecting desulfurization efficiency. The main reason for desulfurization wastewater discharge is to reduce the accumulation of harmful substances and control chloride ion concentration. High chloride ion concentrations accelerate equipment corrosion and affect gypsum crystallization and quality, thus impacting desulfurization efficiency. Therefore, the addition of hydrochloric acid increases the burden on the desulfurization system, ultimately leading to a dramatic increase in the volume of desulfurization wastewater. Summary of the Invention

[0010] To solve the above problems, the application discloses a crystallization granulation fluidized bed coal-fired power plant circulating sewage treatment device and process, first, a crystallization granulation fluidized bed is arranged in front of the clarifier to induce crystallization softening, then a high-density clarifier is used to reduce the amount of reagent, finally, sulfuric acid is used to adjust PH, which is friendly to the desulfurization system, in addition, ultrafiltration + reverse osmosis + concentrated water reverse osmosis is arranged to realize the separation of fresh water and concentrated water.

[0011] The specific scheme is as follows:

[0012] The crystallization granulation fluidized bed coal-fired power plant circulating sewage treatment device comprises a cooling tower pool, a multi-medium filter, a crystallization granulation fluidized bed, a circulating sewage buffer pool, a high-density clarifier, a plug flow ditch, a variable porosity filter tank, a clear water tank, a self-cleaning filter, an ultrafiltration device, an ultrafiltration water tank, an ultraviolet sterilizer, a first security filter and a reverse osmosis device which are connected in sequence.

[0013] Further, the circulating sewage in the water intake area of the cooling tower pool flows into the multi-medium filter through a first lifting pump, and sodium hypochlorite for sterilization is added to the outlet pipeline of the first lifting pump.

[0014] Further, the crystallization granulation fluidized bed is provided with seed crystals and alkali for inducing crystallization to remove hardness, wherein the addition end of the seed crystals is provided with a seed crystal feeding device, a seed crystal storage tank, a seed crystal dosing device, a seed crystal mixing device and a seed crystal feeding pump which are connected in sequence.

[0015] Further, the effluent end of the circulating sewage buffer pool flows into the high-density clarifier through a second lifting pump, and the high-density clarifier is used for coagulation and sedimentation and PH adjustment and comprises a reaction zone, a flocculation zone, a clarification and sedimentation zone and a neutralization zone which are arranged in sequence along the flow direction, and is provided with a sludge discharge port at the bottom.

[0016] Further, the bottom of the variable porosity filter tank is provided with a sludge discharge port, the effluent end of the clear water tank flows into the self-cleaning filter through a third lifting pump, the ultrafiltration water tank is further connected to the ultrafiltration device through an ultrafiltration backwash pump, the ultrafiltration water tank is connected to the ultraviolet sterilizer through a fourth lifting pump, and the first security filter is connected to the reverse osmosis device through a high-pressure pump.

[0017] Further, the fresh water tank is connected with the reverse osmosis device through a reverse osmosis flushing pump, and the fresh water in the fresh water tank is supplied to the boiler as make-up water through a fifth lifting pump.

[0018] Further, the fresh water tank is connected with the reverse osmosis device through a reverse osmosis flushing pump, and the fresh water in the fresh water tank is supplied to the boiler as make-up water through a fifth lifting pump.

[0019] Based on the crystallization granulation fluidized bed circulating blowdown water treatment process of the coal-fired power plant, the following steps are sequentially included:

[0020] S1, pumping the blowdown water in the cooling tower pool into the multi-medium filter through a first lifting pump, and adding sodium hypochlorite for sterilization at the same time;

[0021] S2, filtering out small-particle solid suspensions by the multi-medium filter, and flowing into the crystallization granulation fluidized bed;

[0022] S3, flowing into the circulating blowdown water buffer tank after the crystallization granulation fluidized bed performs induced crystallization hardness removal; this step utilizes specific physical and chemical conditions in the crystallization granulation fluidized bed to induce crystallization reaction of hardness ions such as calcium and magnesium in the wastewater with added crystal seeds, forming particulate substances that are easy to separate and treat. This process not only softens the water quality and reduces the risk of scaling in subsequent treatment, but also avoids the shortcomings of requiring a large amount of softening agent in the traditional softening process, thereby reducing the operating cost and environmental risk.

[0023] S4, pumping into the high-density clarifier through a second lifting pump, sequentially passing through a reaction zone, a flocculation zone, a clarification and precipitation zone, and a neutralization zone, performing coagulation and sedimentation and PH adjustment, and flowing into the plug flow ditch; the high-density clarifier improves the removal efficiency of suspended solids by optimizing the sedimentation conditions, ensuring the stability of the effluent water quality. Since the softening has been achieved by crystallization and granulation in the previous stage, there is no need to add softening agent again in this stage, further reducing the treatment cost; in addition, in order to meet the water quality requirements of the subsequent treatment process, sulfuric acid is used to adjust the PH of the clarifier effluent. This step helps to stabilize the water quality and creates favorable conditions for subsequent ultrafiltration and reverse osmosis treatment. At the same time, by accurately controlling the amount of chloride added, the potential impact on the desulfurization system is reduced, improving the friendliness and stability of the entire system;

[0024] S5, sequentially flowing through a variable-porosity filter tank, a clear water tank, a self-cleaning filter, an ultrafiltration device, an ultrafiltration water tank, an ultraviolet sterilizer, a first security filter, and a reverse osmosis device; the fresh water of the reverse osmosis device is used as make-up water for the boiler, and the concentrated water after the concentrated water reverse osmosis device is still used as make-up water for the boiler, and the concentrated water is transported to the desulfurization for reuse.

[0025] Among them, ultrafiltration as a pretreatment step, effectively removes suspended solids, colloidal and macromolecular organic matter and other impurities in water; reverse osmosis further removes the dissolved salts, heavy metal ions and other small pollutants in water, realizes the effective separation of fresh water and concentrated water. For the concentrated water produced, through the concentrated water reverse osmosis system, the water resource recycling rate is improved.

[0026] In addition, a medium-pressure ultraviolet sterilization device is arranged in front of the security filter, so that full-spectrum sterilization can be realized, and non-oxidizing sterilizing agents do not need to be added. According to the final operation effect, the amount of sodium hypochlorite added in the early stage can also be reduced to cope with the high microbial pollution of the circulating sewage water.

[0027] Further, in step S3, the crystallization prilling fluidized bed is induced to crystallize and remove hardness by adding seeds and alkali, and a seed full-automatic feeding system is arranged at the adding end of the seeds.

[0028] The beneficial effects of the present application are:

[0029] 1. A crystallization prilling fluidized bed is arranged in front of the clarifier, which induces crystallization to soften the water quality, reduces the consumption of limestone, and is friendly to the environment. This process not only softens the water quality and reduces the risk of scaling in subsequent treatment, but also avoids the shortcomings of requiring a large amount of softening agent in the traditional softening process, thereby reducing the operating cost and environmental risk.

[0030] 2. It can remove silicon in a synergistic manner.

[0031] 3. According to the water quality analysis, since the concentrated water is reused to desulfurization, sulfuric acid is used instead of hydrochloric acid, which greatly reduces the generation of desulfurization wastewater;

[0032] 4. Ultrafiltration is used as a pretreatment step to effectively remove suspended solids, colloidal and macromolecular organic matter and other impurities in water; reverse osmosis further removes the dissolved salts, heavy metal ions and other small pollutants in water, realizes the effective separation of fresh water and concentrated water. For the concentrated water produced, through the concentrated water reverse osmosis system, the water resource recycling rate is improved.

[0033] 5. A seed full-automatic feeding system is developed, which can realize automatic feeding, storage, dosing, mixing and feeding of seeds without personnel operation, thereby reducing labor intensity and improving work efficiency and accuracy.

[0034] 6. A medium-pressure ultraviolet sterilization device is arranged in front of the security filter, so that full-spectrum sterilization can be realized, and non-oxidizing sterilizing agents do not need to be added. According to the final operation effect, the amount of sodium hypochlorite added in the early stage can also be reduced to cope with the high microbial pollution of the circulating sewage water.

[0035] 7. Particularly suitable for circulating water fine treatment of built and newly built coal-fired power plants, and practical water resource cascade utilization. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 System block diagram of the device of the present application.

[0037] Figure 2 Schematic diagram of the full-automatic seed feeding system in the device of the present application.

[0038] LIST OF REFERENCE NUMERALS

[0039] 1-cooling tower pool, 2-multiple medium filter, 2.1-sodium hypochlorite, 3-crystallization prilling fluidized bed, 3.1-seed feeding device, 3.2-seed storage tank, 3.3-seed batching device, 3.4-seed mixing device, 3.5-seed feeding pump, 3.6-alkali, 4-circulating blowdown water buffer tank, 5-high-density clarifier, 5.1-reaction zone, 5.1.1-flocculant, 5.2-flocculation zone, 5.2.1-coagulant aid, 5.3-clearing and precipitation zone, 5.4-neutralization zone, 5.4.1-sulfuric acid, 6-push flow ditch, 7-variable porosity filter tank, 8-clear water tank, 9-self-cleaning filter, 10-ultrafiltration device, 10.1-ultrafiltration backwash pump, 11-ultrafiltration water tank, 12-ultraviolet sterilizer, 13-first security filter, 14-high-pressure pump, 15-reverse osmosis device, 15.1-reverse osmosis flushing pump, 16-fresh water tank, 17-first-stage concentrated water tank, 18-second security filter, 19-concentrated water reverse osmosis device, 19.1-concentrated water reverse osmosis flushing pump, 20-final concentrated brine tank, 21-first lifting pump, 22-second lifting pump, 23-third lifting pump, 24-fourth lifting pump, 25-fifth lifting pump, 26-sixth lifting pump. DETAILED DESCRIPTION

[0040] The present application will be further illustrated in conjunction with the drawings and specific embodiments, and it should be understood that the following specific embodiments are only used to illustrate the present application and not to limit the scope of the present application.

[0041] As shown in the figure, the application provides a circulating sewage treatment device for coal-fired power plants based on crystallization granulation fluidized bed, which comprises a cooling tower pool (1), a multi-medium filter (2), a crystallization granulation fluidized bed (3), a circulating sewage buffer pool (4), a high-density clarifier (5), a plug flow ditch (6), a variable porosity filter tank (7), a clear water pool (8), a self-cleaning filter (9), an ultrafiltration device (10), an ultrafiltration water tank (11), an ultraviolet sterilizer (12), a first security filter (13) and a reverse osmosis device (15) connected in sequence; the fresh water end of the reverse osmosis device (15) is connected to a fresh water tank (16), the concentrated water end is connected to a concentrated water reverse osmosis device (19) through a first concentrated water tank (17) and a second security filter (18) in sequence, and the concentrated water end of the concentrated water reverse osmosis device (19) is connected to a final concentrated brine pool (20).

[0042] In this embodiment, the sewage in the water intake area of the cooling tower pool (1) flows into the multi-medium filter (2) through the first lifting pump (21), and sodium hypochlorite (2.1) for sterilization is added at the outlet pipeline of the first lifting pump (21); a stainless steel grille is arranged in the water intake area to intercept fallen leaves, branches and other sundries; the multi-medium filter (2) is used for filtering small-particle solid suspensions.

[0043] In this embodiment, the crystallization granulation fluidized bed (3) is added with seed crystals and alkali (3.6) for inducing crystallization to remove hardness, wherein the addition end of the seed crystals is provided with a seed crystal feeding device (3.1), a seed crystal storage tank (3.2), a seed crystal dosing device (3.3), a seed crystal mixing device (3.4) and a seed crystal feeding pump (3.5) connected in sequence. The whole process of seed crystal feeding, dosing, mixing and storage is automatic without the need for personnel operation, which reduces labor intensity and improves work efficiency and accuracy.

[0044] In this embodiment, the water outlet end of the circulating sewage buffer pool (4) flows into the high-density clarifier (5) through the second lifting pump (22), and the high-density clarifier (5) is used for coagulation and sedimentation and PH adjustment, comprising a reaction zone (5.1), a flocculation zone (5.2), a clarification and sedimentation zone (5.3) and a neutralization zone (5.4) arranged in sequence along the flow direction, and a sludge discharge port is arranged at the bottom, a flocculating agent (5.1.1) is added in the reaction zone (5.1), a coagulant aid (5.2.1) is added in the flocculation zone (5.2), and sulfuric acid (5.4.1) is added in the neutralization zone (5.4).

[0045] In the embodiment, the bottom of the variable-pore filter tank (7) is provided with a sludge discharge port, the outlet end of the clarifying tank (8) flows into the self-cleaning filter (9) through the third lifting pump (23), the ultrafiltration water tank (11) is also connected with the ultrafiltration device (10) through the ultrafiltration backwashing water pump (10.1), the ultrafiltration water tank (11) is connected with the ultraviolet sterilizer (12) through the fourth lifting pump (24), and the first security filter (13) is connected with the reverse osmosis device (15) through the high-pressure pump (14).

[0046] In the embodiment, the fresh water tank (16) is also connected with the reverse osmosis device (15) through the reverse osmosis flushing pump (15.1), and the fresh water in the fresh water tank (16) is used for boiler makeup water through the fifth lifting pump (25).

[0047] In the embodiment, the fresh water tank (16) is connected with the concentrated water reverse osmosis device (19) through the concentrated water reverse osmosis flushing pump (19.1), the fresh water end of the concentrated water reverse osmosis device (19) is connected with the fresh water tank (16), the concentrated water end is connected with the final concentrated brine tank (20), and the concentrated water in the final concentrated brine tank (20) is transported to the desulfurization reuse through the sixth lifting pump (26).

[0048] The application also provides a circulating sewage treatment process for a coal-fired power plant based on a crystallization granulation fluidized bed, which sequentially comprises the following steps:

[0049] S1, the sewage in the cooling tower tank (1) is pumped into the multi-medium filter (2) through the first lifting pump (21), and sodium hypochlorite (2.1) is added at the same time for sterilization;

[0050] S2, the multi-medium filter (2) filters out small-particle solid suspensions and flows into the crystallization granulation fluidized bed (3);

[0051] S3, after the crystallization granulation fluidized bed (3) performs induced crystallization hardness removal, it flows into the circulating sewage buffer tank (4); this step utilizes specific physical and chemical conditions in the crystallization granulation fluidized bed to induce the crystallization reaction of hardness ions such as calcium and magnesium in the wastewater with added crystal seeds, to form particulate substances that are easy to separate and process. This process not only softens the water quality and reduces the risk of scaling in subsequent treatment, but also avoids the shortcomings of needing a large amount of softening agent in the traditional softening process, thereby reducing the operation cost and environmental risk; specifically:

[0052] When alkali (such as NaOH, Na2CO3, etc.) is added and crystal seeds are introduced, calcium ions (Ca²⁺) in the water will react with carbonate ions (CO3²⁻) to form calcium carbonate (CaCO3) crystals. These crystals adhere to and grow on the surface of the crystal seeds, forming calcium carbonate particles that can be recycled. Silicon (Si) and calcium (Ca) in the water combine to form calcium silicate (CaSiO3) and adhere to the calcium carbonate particles, thereby completing the removal of silicon.

[0053] The reason is as follows: silicon does exist irreversible pollution to reverse osmosis membrane, mainly reflected in the formation of silicon scale and its negative impact on membrane performance. Silicon in water mainly exists in two forms: active silicon (soluble silicon) and colloidal silicon. Active silicon is soluble silicon, which is weakly ionized and not polymerized into long chains; while colloidal silicon is polymerized silicon or colloidal, which is more similar to solid in nature, and the diameter can be as small as 0.008 microns. Silicon can form a silicon membrane on the surface of reverse osmosis membrane, which will significantly reduce the water flux and the rejection rate of the membrane. The formation rate of silicon membrane is proportional to the concentration of silicon ions, so water with high silicon content forms a thicker silicon membrane on the reverse osmosis membrane, which has a more serious impact on the performance of the membrane. The self-polymerization of silicon is a kinetic control reaction, when the conditions are suitable (such as temperature rise, pH change, etc.), silicon will rapidly polymerize to form silicon scale. The silicon membrane formed on the surface of the reverse osmosis membrane is difficult to completely remove, which not only shortens the service life of the reverse osmosis membrane, but also affects the physical and chemical properties of the membrane, reducing the stability of the membrane. Silicon pollution is one of the most common and most difficult to deal with membrane pollution problems.

[0054] The wastewater after the above treatment enters the ultrafiltration and reverse osmosis system for deep purification.

[0055] S4, pumped into the high-density clarifier (5) through the second lifting pump (22), and sequentially passes through the reaction zone (5.1), the flocculation zone (5.2), the clarification and sedimentation zone (5.3) and the neutralization zone (5.4) to carry out coagulation sedimentation and pH adjustment, and flows into the plug flow ditch (6); the high-density clarifier improves the removal efficiency of suspended solids by optimizing the sedimentation conditions, ensuring the stability of the effluent water quality. Since the softening has been achieved by crystallization and granulation in the previous stage, it is not necessary to add softening agents at this stage, further reducing the treatment cost; in addition, in order to meet the water quality requirements of the subsequent treatment process, sulfuric acid is used to adjust the pH of the clarifier effluent. This step helps to stabilize the water quality and creates favorable conditions for subsequent ultrafiltration and reverse osmosis treatment. At the same time, by accurately controlling the amount of chloride added, the potential impact on the desulfurization system is reduced, improving the friendliness and stability of the entire system;

[0056] S5, sequentially flows through the variable-porosity filter tank (7), the clear water tank (8), the self-cleaning filter (9), the ultrafiltration device (10), the ultrafiltration water tank (11), the ultraviolet sterilizer (12), the first security filter (13) and the reverse osmosis device (15), the fresh water of the reverse osmosis device (15) is used as boiler makeup water for reuse, and the concentrated water is sent to the desulfurization reuse after passing through the concentrated water reverse osmosis device (19).

[0057] Among them, ultrafiltration as a pretreatment step, effectively removes suspended solids, colloidal and macromolecular organic matter and other impurities in water; Reverse osmosis further removes the dissolved salts, heavy metal ions and other small pollutants in water, realizes the effective separation of fresh water and concentrated water. For the concentrated water produced, the concentrated water reverse osmosis system is used for treatment, and the water resource recovery rate is improved.

[0058] In addition, the medium-pressure ultraviolet sterilization device is arranged before the reverse osmosis security filter, full-spectrum sterilization can be realized, and no non-oxidizing sterilizing agent needs to be added. According to the final operation effect, the sodium hypochlorite dosage in the early stage can also be reduced to cope with the high microbial pollution of the circulating sewage.

[0059] In the embodiment, in step S3, the crystallization prilling fluidized bed (3) is induced to crystallize and remove hardness by adding seeds and alkali (3.6). The seed adding end is provided with a full-automatic seed feeding system, which comprises a seed feeding device (3.1), a seed storage tank (3.2), a seed batching device (3.3), a seed mixing device (3.4) and a seed feeding pump (3.5) connected in sequence. The feeding device (3.1) is a winch, and the discharge end thereof is arranged above the storage tank (3.2). The storage tank (3.2) is a funnel-shaped tank with an open top. The seed batching device (3.3) is arranged at the lower end outlet of the storage tank (3.2). The seed mixing device (3.4) is a mixing kettle, which is arranged below the batching device (3.3) and is provided with a feeding pipe on the side surface. The seed feeding pump (3.5) is arranged on the feeding pipe. The seed feeding, storage, batching, mixing and feeding processes are fully automatic, and no personnel operation is required, thereby reducing the labor intensity and improving the work efficiency and accuracy.

[0060] The technical means disclosed in the present application scheme is not limited to the technical means disclosed in the above-mentioned embodiments, but also includes the technical solutions composed of any combination of the above technical features. It should be noted that for ordinary skilled persons in the art, without departing from the principle of the present application, some improvements and refinements can be made, which are also considered as the protection scope of the present application.

Claims

1. A device for treating circulating blowdown water from a coal-fired power plant based on crystallization granulation fluidized bed, characterized in that it comprises: It includes cooling tower pool (1), multi-medium filter (2), crystallization granulation fluidized bed (3), circulating sewage water buffer tank (4), high-density clarifier (5), push flow ditch (6), variable porosity filter tank (7), clear water tank (8), self-cleaning filter (9), ultrafiltration device (10), ultrafiltration water tank (11), ultraviolet sterilizer (12), first security filter (13) and reverse osmosis device (15) connected in sequence; the fresh water end of the reverse osmosis device (15) is connected with fresh water tank (16), the concentrated water end is connected with concentrated water reverse osmosis device (19) through first-stage concentrated water tank (17) and second security filter (18) in sequence, and the concentrated water end of the concentrated water reverse osmosis device (19) is connected with final concentrated brine tank (20).

2. The crystallization-based granulation fluidized bed combustion coal-fired power plant circulating blowdown water treatment device according to claim 1, characterized in that, The sewage in the water intake area of the cooling tower pool (1) flows into the multi-medium filter (2) through the first lifting pump (21), and sodium hypochlorite (2.1) for sterilization is added at the outlet pipeline of the first lifting pump (21), and a stainless steel grid is arranged in the water intake area for intercepting sundries; the multi-medium filter (2) is used for filtering small-particle solid suspensions.

3. The crystallization-based granulation fluidized bed combustion coal-fired power plant circulating blowdown water treatment device according to claim 1, characterized in that, The crystallization granulation fluidized bed (3) is added with seed crystals and alkali (3.6) for inducing crystallization to remove hardness, wherein the seed crystal adding end is provided with seed crystal feeding device (3.1), seed crystal storage tank (3.2), seed crystal batching device (3.3), seed crystal mixing device (3.4) and seed crystal feeding pump (3.5) connected in sequence.

4. The crystallization-based granulation fluidized bed combustion coal-fired power plant circulating blowdown water treatment device according to claim 1, characterized in that, The water outlet end of the circulating sewage water buffer tank (4) flows into the high-density clarifier (5) through the second lifting pump (22).

5. The crystallization-based granulation fluidized bed combustion coal-fired power plant circulating blowdown water treatment device according to claim 1, characterized in that, The high-density clarifier (5) is used for coagulation sedimentation and PH adjustment, and includes reaction zone (5.1), flocculation zone (5.2), clarification and sedimentation zone (5.3) and neutralization zone (5.4) arranged in sequence along the flow direction, and is provided with a sludge discharge port at the bottom, the reaction zone (5.1) is added with flocculant (5.1.1), the flocculation zone (5.2) is added with coagulant aid (5.2.1), and the neutralization zone (5.4) is added with sulfuric acid (5.4.1).

6. The crystallization-based granulation fluidized bed combustion coal-fired power plant circulating blowdown water treatment device according to claim 1, characterized in that, The bottom of the variable porosity filter tank (7) is provided with a sludge discharge port, and the water outlet end of the clear water tank (8) flows into the self-cleaning filter (9) through the third lifting pump (23).

7. The crystallization-based granulation fluidized bed combustion coal-fired power plant circulating blowdown water treatment device according to claim 1, characterized in that, The ultrafiltration water tank (11) is further connected with the ultrafiltration device (10) through the ultrafiltration backwashing pump (10.1), the ultrafiltration water tank (11) is connected with the ultraviolet sterilizer (12) through the fourth lifting pump (24), and the first security filter (13) is connected with the reverse osmosis device (15) through the high-pressure pump (14).

8. The crystallization-based granulation fluidized bed coal-fired power plant circulating blowdown water treatment device according to claim 1, characterized by, The fresh water tank (16) and the reverse osmosis device (15) are further connected through the reverse osmosis washing pump (15.1), and the fresh water in the fresh water tank (16) is supplied to the boiler as make-up water through the fifth lifting pump (25) for reuse.

9. The crystallization-based granulation fluidized bed combustion coal-fired power plant circulating blowdown water treatment device according to claim 1, characterized in that, The fresh water tank (16) and the concentrated water reverse osmosis device (19) are connected through the concentrated water reverse osmosis washing pump (19.1), the fresh water end of the concentrated water reverse osmosis device (19) is connected with the fresh water tank (16), and the concentrated water end is connected with the final concentrated brine tank (20).

10. The crystallization-based granulation fluidized bed coal-fired power plant circulating blowdown water treatment device according to claim 1, characterized by, The concentrated water of the final concentrated brine pool (20) is delivered to desulfurization reuse by a sixth lifting pump (26).

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