A method for makeup water in a power plant circulating cooling water system

Abstract

This invention provides a method for replenishing water in a power plant's circulating cooling water system. The method includes: 1) determining the ammonia nitrogen concentration, nitrogen-to-phosphorus ratio, concentration ratio, and temperature of the circulating cooling water entering the cooling tower to achieve the dominance of nitrifying and nitrite-oxidizing bacteria in the packing material of the cooling tower; 2) adjusting the ammonia nitrogen concentration in the municipal water to achieve the ammonia nitrogen concentration and nitrogen-to-phosphorus ratio determined in step 1), thus obtaining replenishing water for the circulating cooling water system; 3) determining the replenishing water volume based on the concentration ratio determined in step 1); 4) using the replenishing water obtained in step 2) as replenishing water for the circulating cooling water system according to the replenishing water volume determined in step 3), while simultaneously controlling the temperature of the circulating cooling water in the system to the temperature determined in step 1).

Description

Technical Field

[0001] This invention relates to a method for replenishing water in a power plant's circulating cooling water system. Background Technology

[0002] Coal-fired power plants consume large amounts of water, with cooling water accounting for 60%-80% of their total water usage. Water scarcity is a significant obstacle to the development of the coal-fired power industry. If urban wastewater could be reused in circulating cooling water systems, it would greatly alleviate the water shortage-induced development challenges faced by the coal-fired power industry.

[0003] Urban greywater is characterized by high salt content, high organic matter content, and high ammonia nitrogen content. Directly reusing urban greywater in circulating cooling water systems can lead to a series of problems, the most important of which are scaling, corrosion, and the growth of biological slime.

[0004] To realize the reuse of urban greywater in circulating cooling water systems, industry professionals have conducted research and proposed several technical solutions, such as:

[0005] Chemical treatment methods. Currently, the most common method involves adding certain amounts of scale inhibitors, corrosion inhibitors, and microbial killers to achieve scale inhibition, corrosion inhibition, and microbial elimination. Scale inhibitors used in industrial circulating cooling water mainly include polyphosphates, organophosphonic acids, phosphonic acids, organophosphate esters, and polycarboxylic acids. Corrosion inhibitors mainly include chromates, polyphosphates, nitrites, zinc salts, molybdates, tungstates, and organophosphonates. Microbial killers are mainly divided into oxidizing and non-oxidizing types. However, the extensive use of chemical agents can deteriorate the quality of circulating cooling water, causing secondary pollution.

[0006] Physical treatment methods. Currently, the most common include magnetized water treatment and electrostatic water treatment. Magnetized water treatment uses electric and magnetic fields to prevent scale-causing substances (calcium and magnesium carbonates and sulfates) from precipitating onto container walls. Electrostatic water treatment inhibits scale and corrosion by altering the structure of water molecules. However, the magnetic field strength in magnetized water treatment is limited by the magnetic materials and magnetization technology, and demagnetization can occur over time or with increased water temperature. Electrostatic water treatment requires high standards for system chemical dosing and daily management.

[0007] Ultrafiltration-reverse osmosis treatment method. Ultrafiltration membranes are selectively permeable membranes with mechanical screening capabilities, effectively intercepting viruses, pathogens, particles, colloids, oils, and macromolecules in wastewater. Because ultrafiltration can only remove large organic molecules, it is used for wastewater pretreatment and combined with reverse osmosis technology to ensure the feed water quality requirements of the reverse osmosis membrane. However, factors such as pH and temperature significantly affect the desalination and recovery rates of reverse osmosis, leading to unstable treatment results. Furthermore, the high cost of ultrafiltration membranes makes industrial-scale application difficult.

[0008] Therefore, new technical solutions are still needed to realize the reuse of urban greywater in circulating cooling water systems. Summary of the Invention

[0009] The purpose of this invention is to provide a technical solution that enables the reuse of urban greywater in a circulating cooling water system.

[0010] To achieve the above objectives, the present invention provides a method for makeuping water in a power plant circulating cooling water system, the method comprising:

[0011] 1) Determine the ammonia nitrogen concentration in the makeup water, the nitrogen-to-phosphorus ratio in the makeup water, the concentration ratio, and the temperature of the circulating cooling water entering the cooling tower to achieve the emergence of nitrifying bacteria and nitrite bacteria as the dominant microbial species in the packing material of the cooling tower in the circulating cooling water system.

[0012] 2) Adjust the ammonia nitrogen concentration of the urban water to the ammonia nitrogen concentration of the makeup water determined in step 1), and adjust the nitrogen-phosphorus ratio of the urban water to the nitrogen-phosphorus ratio of the makeup water determined in step 1) to obtain the makeup water for the circulating cooling water system.

[0013] 3) Determine the amount of water to add based on the concentration ratio determined in step 1);

[0014] 4) Use the water replenishment water obtained in step 2) as the replenishment water for the circulating cooling water system according to the replenishment water amount determined in step 3), and at the same time control the temperature of the circulating cooling water in the circulating cooling water system to the temperature determined in step 1).

[0015] In the above-mentioned method for replenishing water in the circulating cooling water system of a power plant, by adjusting the ammonia nitrogen content and nitrogen-phosphorus ratio of the water in the replenishing water city, as well as the concentration ratio and temperature of the circulating cooling water, the microbial population living in the packing material inside the cooling tower of the circulating cooling water system is made to have nitrifying bacteria and nitrite-oxidizing bacteria as the dominant species. This ensures that the ammonia nitrogen content and organic matter in the circulating cooling water can always be kept at a low level and can effectively inhibit scaling, corrosion and the growth of biological slime.

[0016] In the above-mentioned method for replenishing water in the circulating cooling water system of a power plant, preferably, the method further includes real-time monitoring of the ammonia nitrogen concentration of the circulating cooling water in the circulating cooling water system. When the ammonia nitrogen concentration exceeds the ammonia nitrogen concentration threshold, pure water is used to replace the water replenished in the circulating cooling water system obtained in step 2) as the replenished water for the circulating cooling water system. The replenishment amount is determined in step 3) and the water replenishment is carried out until the ammonia nitrogen concentration of the circulating cooling water in the cooling water system is lower than the ammonia nitrogen concentration threshold.

[0017] More preferably, the ammonia nitrogen concentration threshold is 6 mg / L.

[0018] In the above-mentioned method for replenishing water in the circulating cooling water system of a power plant, preferably, in step 2), when the ammonia nitrogen concentration of the replenished water is higher than that of the urban water and the nitrogen-phosphorus ratio of the replenished water is higher than that of the urban water, the ammonia nitrogen concentration and nitrogen-phosphorus ratio of the urban water are increased by adding ammonium chloride to the urban water.

[0019] In the above-mentioned method for replenishing water in a power plant circulating cooling water system, preferably, in step 1), during the process of determining the replenishment water ammonia nitrogen concentration, replenishment water nitrogen-phosphorus ratio, concentration ratio, and circulating cooling water temperature entering the cooling tower to achieve the emergence of nitrifying bacteria and nitrite bacteria as the dominant microbial species in the packing material of the cooling tower of the circulating cooling water system, the replenishment water ammonia nitrogen concentration is determined to be within the range of 1.0 to 2.5 times the ammonia nitrogen concentration of urban water, the replenishment water nitrogen-phosphorus ratio is determined to be within the range of 1.0 to 2.5 times the nitrogen-phosphorus ratio of urban water, the concentration ratio is determined to be within the range of 1.0 to 2.5, and the temperature is determined to be within the range of 25℃ to 40℃.

[0020] In the above-mentioned method for replenishing water in the circulating cooling water system of a power plant, preferably, in step 1), the concentration of ammonia nitrogen in the replenishing water, the nitrogen-phosphorus ratio in the replenishing water, the concentration ratio, and the temperature of the circulating cooling water entering the cooling tower are determined through indoor simulation experiments to achieve the emergence of nitrifying bacteria and nitrite bacteria as the dominant microbial species in the packing material of the cooling tower in the circulating cooling water system.

[0021] More preferably, the determination of the makeup water ammonia nitrogen concentration, makeup water nitrogen-to-phosphorus ratio, concentration ratio, and circulating cooling water temperature entering the cooling tower, which enable the microbial population living in the cooling tower packing material of the circulating cooling water system to achieve the dominance of nitrifying bacteria and nitrite bacteria, includes:

[0022] A. The temperature of the circulating cooling water entering the cooling tower is determined by a single-factor indoor simulation experiment to determine the optimal temperature for the growth of heterotrophic bacteria in the packing material of the cooling tower in a circulating cooling water system. This temperature is considered the optimal temperature for the growth of nitrifying bacteria and nitrite bacteria in the packing material of the cooling tower in a circulating cooling water system.

[0023] B. The appropriate ammonia nitrogen concentration in the make-up water for the growth of heterotrophic bacteria in the packing material of the cooling tower in a circulating cooling water system was determined by a single-factor indoor simulation experiment on the ammonia nitrogen concentration in the make-up water. This concentration is used to determine the ammonia nitrogen concentration in the make-up water that enables nitrifying bacteria and nitrite bacteria to become the dominant microbial species in the packing material of the cooling tower in a circulating cooling water system.

[0024] C. The concentration ratio suitable for the growth of heterotrophic bacteria in the packing material of the cooling tower in the circulating cooling water system was determined by a single-factor indoor simulation experiment of concentration ratio. This concentration ratio is used to determine the microbial population in the packing material of the cooling tower in the circulating cooling water system where nitrifying bacteria and nitrite bacteria become the dominant species.

[0025] D. Under the conditions of the circulating cooling water temperature entering the cooling tower determined in step A, the ammonia nitrogen concentration of the makeup water determined in step B, and the concentration ratio determined in step C, the suitable makeup water nitrogen-phosphorus ratio for the growth of nitrifying and nitrite-oxidizing bacteria in the packing material of the cooling tower in the circulating cooling water system is determined by a single-factor indoor simulation experiment of the makeup water nitrogen-phosphorus ratio. This ratio is used to determine the makeup water nitrogen-phosphorus ratio that enables the emergence of nitrifying and nitrite-oxidizing bacteria as the dominant species in the microbial population living in the packing material of the cooling tower in the circulating cooling water system.

[0026] This preferred technical solution first determines the suitable circulating cooling water temperature, makeup water ammonia nitrogen concentration, and concentration ratio for the growth of heterotrophic bacteria in the packing material of the cooling tower within the circulating cooling water system. Then, under the conditions of the determined suitable circulating cooling water temperature, makeup water ammonia nitrogen concentration, and concentration ratio for the growth of nitrifying and nitrite-oxidizing bacteria in the packing material of the cooling tower, the solution determines the appropriate makeup water nitrogen-phosphorus ratio for the growth of nitrifying and nitrite-oxidizing bacteria in the packing material. This method achieves the determination of the makeup water ammonia nitrogen concentration, makeup water nitrogen-phosphorus ratio, concentration ratio, and circulating cooling water temperature for the emergence of nitrifying and nitrite-oxidizing bacteria as the dominant species in the packing material of the circulating cooling water system. Statistical analysis of the growth of nitrifying and nitrite-oxidizing bacteria is difficult and costly. This method minimizes the need for such analysis, requiring it only during the determination of the makeup water nitrogen-phosphorus ratio. This reduces the difficulty and cost of indoor experiments and improves the success rate of indoor experiments.

[0027] More preferably, the determination of the makeup water ammonia nitrogen concentration, makeup water nitrogen-to-phosphorus ratio, concentration ratio, and circulating cooling water temperature entering the cooling tower, which enable the microbial population living in the cooling tower packing material of the circulating cooling water system to have nitrifying bacteria and nitrite bacteria as the dominant species, further includes:

[0028] Before proceeding with steps A, B, and C, orthogonal indoor simulation experiments were conducted to determine the possible range of circulating cooling water temperature, makeup water ammonia nitrogen concentration, and concentration ratio suitable for the growth of heterotrophic bacteria in the packing material of the cooling tower in a circulating cooling water system.

[0029] The possible ranges of the circulating cooling water temperature, makeup water ammonia nitrogen concentration, and concentration ratio entering the cooling tower for the growth of heterotrophic bacteria in the packing material of the cooling tower in the determined suitable circulating cooling water system are used as the experimental research ranges of the circulating cooling water temperature, makeup water ammonia nitrogen concentration, and concentration ratio entering the cooling tower in the single-factor experiments of steps A, B, and C, respectively.

[0030] More preferably, the indoor simulation experiment is conducted using an indoor simulation device for a circulating cooling water system; the indoor simulation device for the circulating cooling water system includes: a cooling tower, an automatic water replenishment device for an ammonia nitrogen detector, a thermometer, a flow meter, a circulating water pump, and heating equipment; wherein,

[0031] The cooling tower has a cold water pool, a makeup water inlet, a circulating water inlet, and a circulating water outlet at its bottom. Inside the cooling tower, there is a packing zone and a spray system. The makeup water inlet and the circulating water inlet are connected to the inlet of the spray system, and the outlet of the spray system is equipped with nozzles positioned above the packing zone. The circulating water outlet is connected to the cold water pool. This allows the makeup water and circulating water entering the cooling tower to be sprayed into the packing zone, treated, and then enter the cold water pool. Water in the cold water pool is discharged from the cooling tower through the circulating water outlet. The cooling tower also has an air inlet and outlet.

[0032] An automatic ammonia nitrogen detector water replenishment device is installed in the cooling water tank of the cooling tower and connected to the water replenishment inlet of the cooling tower. The automatic ammonia nitrogen detector water replenishment device is used to monitor the ammonia nitrogen concentration of the circulating cooling water in the cooling water tank in real time and control the water replenishment of the indoor simulation device of the circulating cooling water system. The circulating water outlet of the cooling tower is connected to the water inlet of the heating equipment through a circulating water pipeline, and the water outlet of the heating equipment is connected to the circulating water inlet of the cooling tower through a circulating water pipeline. A circulating water pump, flow meter, and thermometer are installed on the circulating water pipeline.

[0033] More preferably, the number of circulating water pumps, flow meters, and thermometers is not less than two each, and circulating water pumps, flow meters, and thermometers are installed on the circulating water pipeline between the circulating water outlet of the cooling tower and the water inlet of the heating equipment, and circulating water pumps, flow meters, and thermometers are installed on the circulating water pipeline between the water outlet of the heating equipment and the circulating water inlet of the cooling tower.

[0034] More preferably, the packing area is provided with at least 5 sampling points, including a sampling point at the upper part of the central axis of the packing area, a sampling point in the middle of the central axis, a sampling point at the lower part of the central axis, a sampling point on the left side of the packing area, and a sampling point on the right side of the packing area.

[0035] The water replenishment method for power plant circulating cooling water systems provided by this invention utilizes factors such as the ammonia nitrogen concentration, nitrogen-to-phosphorus ratio, concentration ratio, and temperature of the circulating cooling water entering the cooling tower to guide water replenishment, ensuring the dominance of nitrifying and nitrite bacteria in the microbial community living in the packing material within the cooling tower. This achieves the reuse of municipal greywater in the circulating cooling water system while effectively controlling scaling, corrosion, and biofilm growth. It provides a pathway for the application of municipal greywater in power plant circulating cooling water systems, enriches methods for reducing equipment corrosion and scaling, conserves industrial water, ensures efficient and continuous operation of cooling towers, and ultimately safeguards the safe and stable operation of thermal power plant systems. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the indoor simulation device for the circulating cooling water system in Example 1.

[0037] Figure 2 This is a diagram showing the sampling point setup in the packing area in Example 1.

[0038] Figure 3 This is a graph showing the relationship between the maximum number of heterotrophic bacteria and temperature in Example 1.

[0039] Figure 4 This is a diagram of the POT model analysis under the single-factor temperature condition in Example 1.

[0040] Figure 5 This is a graph showing the relationship between the maximum number of heterotrophic bacteria and the ammonia nitrogen concentration in the makeup water in Example 1.

[0041] Figure 6 This is a POT model analysis diagram showing the ammonia nitrogen concentration in the makeup water under a single factor in Example 1.

[0042] Figure 7 This is a graph showing the relationship between the maximum number of heterotrophic bacteria and the concentration ratio in Example 1.

[0043] Figure 8 This is a POT model analysis diagram under the single factor of concentration ratio in Example 1.

[0044] Figure 9 This is a comparison chart of the number of heterotrophic bacteria on the first day in Example 1 at the standard nitrogen-phosphorus ratio and the high nitrogen-phosphorus ratio.

[0045] Figure 10 This is a comparison chart of the number of heterotrophic bacteria on the third day in Example 1 at the standard nitrogen-phosphorus ratio and the high nitrogen-phosphorus ratio.

[0046] Figure 11 This is a comparison chart of the number of heterotrophic bacteria on the fifth day in Example 1 at the standard nitrogen-phosphorus ratio and the high nitrogen-phosphorus ratio.

[0047] Figure 12 This is a graph showing the change of ammonia nitrogen concentration over time in Example 1.

[0048] Figure 13 This is a graph showing the change in total phosphorus concentration over time in Example 1.

[0049] Figure 14 This is a species analysis diagram of the Pan sample in Example 1.

[0050] Figure 15 This is a species analysis diagram of the Core sample in Example 1.

[0051] Figure 16 This is a dilution curve for biodiversity analysis of samples in Example 1.

[0052] Figure 17 This is a community composition analysis diagram from Example 1. Detailed Implementation

[0053] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0054] Due to its high salt content, high organic matter content, and high ammonia nitrogen content, urban greywater cannot be directly reused in conventional power plant circulating cooling water systems as makeup water. Using urban greywater directly as makeup water in conventional power plant circulating cooling water systems easily leads to three major problems: scaling, corrosion, and the growth of biological slime. Existing technologies for reusing urban greywater in circulating cooling water systems typically require additional water treatment processes, such as chemical reagent treatment, membrane osmosis treatment, and physical purification treatment, which significantly increase costs. To achieve low-cost urban greywater reuse in circulating cooling water systems, the inventors have conducted extensive research.

[0055] Nitrogen in circulating cooling water primarily exists as ammonia nitrogen. On one hand, ammonia nitrogen is an essential nutrient source for nitrifying and nitrite-oxidizing bacteria in their nitrification reactions. Under well-ventilated conditions, nitrifying bacteria can oxidize ammonia in water into nitrite and nitrate. Specifically: first, nitrite-oxidizing bacteria oxidize ammonia to nitrite (2NH3 + 3O2 → 2HNO2 + 2H2O + energy); then, nitrifying bacteria oxidize nitrite to nitrate (2HNO2 + O2 → 2HNO3 + energy). Through nitrification, nitrifying and nitrite-oxidizing bacteria convert ammonia nitrogen into nitrate and nitrite, thus lowering the pH and reducing eutrophication. On the other hand, since most bacteria in the circulating cooling system are heterotrophic, nitrogen is a major nutrient element for microbial growth. Furthermore, the open cooling tower maintains a moderate water temperature (32-42℃ year-round), a neutral pH, and sufficient nutrients, with an air volume of 2000 m³ / m³ of water per cubic meter of water within the tower. 3 The conditions of complete dissolved oxygen saturation and sufficient light provide a suitable growth environment for bacteria. The growth and reproduction of microorganisms can cause corrosion and biofilm buildup in the circulating cooling system. This biofilm and corrosion products cover the surface of the cooling equipment, reducing the cooling effect and clogging the cooling water channels. By controlling the ammonia nitrogen content and nitrogen-to-phosphorus ratio of the municipal wastewater, as well as the concentration ratio and temperature of the circulating cooling water, so that nitrifying and nitrite-oxidizing bacteria become the dominant microbial populations in the packing material of the cooling tower, the ammonia nitrogen content and organic matter in the circulating cooling water can be maintained at a low level, effectively inhibiting scaling, corrosion, and biofilm growth. Based on this, this invention proposes a novel method for makeup water in power plant circulating cooling water systems using municipal wastewater as makeup water.

[0056] A specific embodiment of the present invention provides a method for makeup water in a power plant circulating cooling water system, the method comprising:

[0057] Step S1: Determine the following parameters to achieve the dominance of nitrifying and nitrite bacteria in the packing material of the cooling tower: ammonia nitrogen concentration in the makeup water, nitrogen-phosphorus ratio in the makeup water, concentration ratio, and temperature of the circulating cooling water entering the cooling tower.

[0058] Step S2: Adjust the ammonia nitrogen concentration of the urban water to the ammonia nitrogen concentration of the makeup water determined in Step S1, and adjust the nitrogen-phosphorus ratio of the urban water to the nitrogen-phosphorus ratio of the makeup water determined in Step S1, to obtain the makeup water in the circulating cooling water system.

[0059] Step S3: Determine the amount of water to be added based on the concentration ratio determined in step S1;

[0060] Step S4: Use the water replenishment water obtained in step S2 as the replenishment water for the circulating cooling water system according to the replenishment water amount determined in step S3, and at the same time control the temperature of the circulating cooling water in the circulating cooling water system to the temperature determined in step 1).

[0061] Furthermore, the method also includes real-time monitoring of the ammonia nitrogen concentration of the circulating cooling water in the circulating cooling water system. When the ammonia nitrogen concentration exceeds the ammonia nitrogen concentration threshold, pure water is used to replace the water replenishment water in the circulating cooling water system obtained in step 2 as the water replenishment water for the circulating cooling water system. The water replenishment water for the circulating cooling water system is carried out according to the water replenishment amount determined in step S3 until the ammonia nitrogen concentration of the circulating cooling water in the cooling water system is lower than the ammonia nitrogen concentration threshold.

[0062] The preferred ammonia nitrogen concentration threshold is 6 mg / L.

[0063] Furthermore, in step S2, when step S1 determines that the ammonia nitrogen concentration of the replenished water is higher than that of the urban water and the nitrogen-phosphorus ratio of the replenished water is higher than that of the urban water, the ammonia nitrogen concentration and nitrogen-phosphorus ratio of the urban water are increased by adding ammonium chloride to the urban water.

[0064] Further, in step S1, during the process of determining the ammonia nitrogen concentration in the makeup water, the nitrogen-phosphorus ratio in the makeup water, the concentration ratio, and the temperature of the circulating cooling water entering the cooling tower to achieve the emergence of nitrifying bacteria and nitrite bacteria as the dominant microbial populations in the packing material inside the cooling tower of the circulating cooling water system, the ammonia nitrogen concentration in the makeup water is determined to be within the range of 1.0 to 2.5 times the ammonia nitrogen concentration of urban wastewater, the nitrogen-phosphorus ratio in the makeup water is determined to be within the range of 1.0 to 2.5 times the nitrogen-phosphorus ratio of urban wastewater, the concentration ratio is determined to be within the range of 1.0 to 2.5, and the temperature is determined to be within the range of 25°C to 40°C.

[0065] Further, in step S1, the concentration of ammonia nitrogen in the makeup water, the nitrogen-phosphorus ratio in the makeup water, the concentration ratio, and the temperature of the circulating cooling water entering the cooling tower are determined through indoor simulation experiments to achieve the emergence of nitrifying bacteria and nitrite bacteria as the dominant microbial species in the packing material inside the cooling tower of the circulating cooling water system.

[0066] Furthermore, determining the makeup water ammonia nitrogen concentration, makeup water nitrogen-to-phosphorus ratio, concentration ratio, and circulating cooling water temperature entering the cooling tower to achieve the dominance of nitrifying and nitrite-oxidizing bacteria in the packing material of the circulating cooling water system includes:

[0067] A. The temperature of the circulating cooling water entering the cooling tower is determined by a single-factor indoor simulation experiment to determine the optimal temperature for the growth of heterotrophic bacteria in the packing material of the cooling tower in a circulating cooling water system. This temperature is considered the optimal temperature for the growth of nitrifying bacteria and nitrite bacteria in the packing material of the cooling tower in a circulating cooling water system.

[0068] B. The appropriate ammonia nitrogen concentration in the make-up water for the growth of heterotrophic bacteria in the packing material of the cooling tower in a circulating cooling water system was determined by a single-factor indoor simulation experiment on the ammonia nitrogen concentration in the make-up water. This concentration is used to determine the ammonia nitrogen concentration in the make-up water that enables nitrifying bacteria and nitrite bacteria to become the dominant microbial species in the packing material of the cooling tower in a circulating cooling water system.

[0069] C. The concentration ratio suitable for the growth of heterotrophic bacteria in the packing material of the cooling tower in the circulating cooling water system was determined by a single-factor indoor simulation experiment of concentration ratio. This concentration ratio is used to determine the microbial population in the packing material of the cooling tower in the circulating cooling water system where nitrifying bacteria and nitrite bacteria become the dominant species.

[0070] D. Under the conditions of the circulating cooling water temperature entering the cooling tower determined in step A, the ammonia nitrogen concentration of the makeup water determined in step B, and the concentration ratio determined in step C, the suitable makeup water nitrogen-phosphorus ratio for the growth of nitrifying and nitrite-oxidizing bacteria in the packing material of the cooling tower in the circulating cooling water system is determined by a single-factor indoor simulation experiment of the makeup water nitrogen-phosphorus ratio. This ratio is used to determine the makeup water nitrogen-phosphorus ratio that enables the emergence of nitrifying and nitrite-oxidizing bacteria as the dominant species in the microbial population living in the packing material of the cooling tower in the circulating cooling water system.

[0071] Furthermore, the determination of the makeup water ammonia nitrogen concentration, makeup water nitrogen-to-phosphorus ratio, concentration ratio, and the temperature of the circulating cooling water entering the cooling tower, which enable the microbial population living in the packing material of the cooling tower to have nitrifying bacteria and nitrite bacteria as the dominant species, also includes:

[0072] Before proceeding with steps A, B, and C, orthogonal indoor simulation experiments were conducted to determine the possible range of circulating cooling water temperature, makeup water ammonia nitrogen concentration, and concentration ratio suitable for the growth of heterotrophic bacteria in the packing material of the cooling tower in a circulating cooling water system.

[0073] The possible ranges of the circulating cooling water temperature, makeup water ammonia nitrogen concentration, and concentration ratio entering the cooling tower for the growth of heterotrophic bacteria in the packing material of the cooling tower in the determined suitable circulating cooling water system are used as the experimental research ranges of the circulating cooling water temperature, makeup water ammonia nitrogen concentration, and concentration ratio entering the cooling tower in the single-factor experiments of steps A, B, and C, respectively.

[0074] Furthermore, the indoor simulation experiment is conducted using an indoor simulation device for a circulating cooling water system; the indoor simulation device for the circulating cooling water system includes: a cooling tower, an automatic water replenishment device for an ammonia nitrogen detector, a thermometer, a flow meter, a circulating water pump, and heating equipment; wherein,

[0075] The cooling tower has a cold water pool, a makeup water inlet, a circulating water inlet, and a circulating water outlet at the bottom. The cooling tower is equipped with a packing area and a spraying device. The makeup water inlet and the circulating water inlet are connected to the water inlet of the spraying device. The water outlet of the spraying device is equipped with a nozzle, which is located above the packing area. The cooling tower is equipped with an air inlet and outlet.

[0076] The ammonia nitrogen detector's automatic water replenishment device is connected to the cooling tower's water replenishment inlet; the cooling tower's circulating water outlet is connected to the heating equipment's water inlet via a circulating water pipeline, and the heating equipment's water outlet is connected to the cooling tower's circulating water inlet via a circulating water pipeline; the circulating water pump, flow meter, and thermometer are installed on the circulating water pipeline.

[0077] Furthermore, the number of circulating water pumps, flow meters, and thermometers shall not be less than two each. Circulating water pumps, flow meters, and thermometers shall be installed on the circulating water pipeline between the circulating water outlet of the cooling tower and the water inlet of the heating equipment, and circulating water pumps, flow meters, and thermometers shall be installed on the circulating water pipeline between the water outlet of the heating equipment and the circulating water inlet of the cooling tower.

[0078] Furthermore, the packing area is equipped with at least five sampling points, including a sampling point at the upper part of the central axis of the packing area, a sampling point in the middle of the central axis, a sampling point at the lower part of the central axis, a sampling point on the left side of the packing area, and a sampling point on the right side of the packing area.

[0079] Example 1

[0080] This embodiment provides a method for makeup water in a power plant's circulating cooling water system, including:

[0081] 1. Using an indoor simulation device for circulating cooling water systems, indoor experiments were conducted to determine the optimal conditions for achieving the dominance of nitrifying and nitrite bacteria in the packing material of the cooling tower within the circulating cooling water system, including the ammonia nitrogen concentration in the makeup water, the nitrogen-to-phosphorus ratio in the makeup water, the concentration ratio, and the temperature of the circulating cooling water entering the cooling tower.

[0082] Among them, the indoor simulation device for the circulating cooling water system, such as Figure 1 The device shown includes: a cooling tower 1, an automatic water replenishment device for an ammonia nitrogen detector 2, a first thermometer 3, a second thermometer 4, a first flow meter 5, a second flow meter 6, a first circulating water pump 7, a second circulating water pump 8, and a heating device 9.

[0083] The cooling tower 1 has a cold water pool 11, a makeup water inlet 12, a circulating water inlet 13, and a circulating water outlet 14 at its bottom. Inside the cooling tower 1, there is a packing zone 15 and a spraying device 16. The makeup water inlet 12 and the circulating water inlet 13 are respectively connected to the inlet of the spraying device 16. The outlet of the spraying device 16 is equipped with a nozzle, which is located above the packing zone 15. The circulating water outlet 14 is connected to the cold water pool 11, so that the makeup water and circulating water entering the cooling tower 1 are sprayed to the packing zone 15 by the spraying device 16, treated by the packing zone 15, and then enter the cold water pool 11. The water in the cold water pool 11 is discharged from the cooling tower 1 through the circulating water outlet 14. The cooling tower 1 is equipped with an air outlet 17 and an air inlet 18.

[0084] An automatic water replenishment device 2 for ammonia nitrogen detector is installed in the cold water pool 11 of cooling tower 1 and connected to the water replenishment inlet 12 of cooling tower 1. The automatic water replenishment device 2 for ammonia nitrogen detector is used to monitor the ammonia nitrogen concentration of the circulating cooling water in the cold water pool 1 in real time and control the water replenishment of the indoor simulation device of the circulating cooling water system. The circulating water outlet 14 of cooling tower 1 is connected to the water inlet of heating device 9 through a circulating water pipeline. The water outlet of heating device 9 is connected to the circulating water inlet 13 of cooling tower 1 through a circulating water pipeline. The first circulating water pump 7, the first flow meter 5, and the first thermometer 3 are installed on the circulating water pipeline between the circulating water outlet 14 of cooling tower 1 and the water inlet of heating device 9. The second circulating water pump 8, the second flow meter 6, and the second thermometer 4 are installed on the circulating water pipeline between the water outlet of heating device 9 and the circulating water inlet 13 of cooling tower 1.

[0085] Packing zone 15 Figure 2 The sampler is provided with five sampling points: sampling point b at the top of the central axis of the packing area, sampling point d at the middle of the central axis, sampling point e at the bottom of the central axis, sampling point a at the left side of the packing area, and sampling point b at the right side of the packing area.

[0086] This step specifically includes:

[0087] 1.1. Using the above-mentioned indoor simulation device for the circulating cooling water system, an orthogonal indoor circulating cooling water system simulation experiment was conducted to simulate the temperature of the circulating cooling water entering the cooling tower, the ammonia nitrogen concentration of the makeup water, and the concentration ratio. The circulating cooling water temperatures entering the cooling tower were 25℃, 30℃, 35℃, 40℃, and 45℃, the concentration ratios were 1, 1.5, 2, 2.5, and 3, and the ammonia nitrogen concentrations were 12 mg / L, 18 mg / L, 24 mg / L, 30 mg / L, and 36 mg / L, respectively. 25 sets of experiments were conducted according to Table 1, involving 3 factors (circulating cooling water temperature entering the cooling tower, ammonia nitrogen concentration of the makeup water, and concentration ratio).

[0088] Table 1

[0089]

[0090] Orthogonal experiments show that the temperature of the circulating cooling water entering the cooling tower, the concentration of ammonia nitrogen in the makeup water, and the concentration ratio have a significant impact on the experiment. The suitable temperature of the circulating cooling water entering the cooling tower should be between 25-40℃, the suitable concentration ratio should be between 1-2.5, and the suitable concentration of ammonia nitrogen in the makeup water should be less than 12mg / L.

[0091] 1.2. Using the aforementioned indoor simulation device for the circulating cooling water system, the suitable temperature for the growth of heterotrophic bacteria in the packing material of the cooling tower within the circulating cooling water system was determined through a single-factor indoor simulation experiment. This temperature was then used as the temperature at which nitrifying and nitrite-oxidizing bacteria became the dominant microbial species in the packing material of the cooling tower. Specifically:

[0092] Using the aforementioned indoor simulation device for the circulating cooling water system, under the premise that other operating conditions remain unchanged (ammonia nitrogen concentration is 1.0 times that of urban wastewater (i.e., 4.286 mg / L), concentration ratio is 1, and nitrogen-phosphorus ratio is 1.0 times that of urban wastewater (i.e., 12.459)), an indoor circulating cooling water system simulation experiment was conducted at different temperatures of the circulating cooling water entering the cooling tower (within the range of 25-40℃, with different temperatures taken in 5℃ increments). The number of heterotrophic bacteria at sampling points a, b, c, d, and e in the packing material was measured continuously for 5 days (bacterial counting was performed using the plate count method). The results are shown in Tables 2A, 2B, 2C, and 2D. The maximum number of heterotrophic bacteria measured at each temperature was also statistically analyzed (e.g., ...). Figure 3 As shown), the POT model is then used to analyze the data (e.g. Figure 4 As shown in the figure, the temperature of the circulating cooling water entering the cooling tower is determined to be the temperature at which nitrifying bacteria and nitrite bacteria become the dominant species in the packing material of the cooling tower in a circulating cooling water system.

[0093] like Figure 3 As shown, in the single-factor indoor simulation experiment of temperature, the maximum number of heterotrophic bacteria generally increased with increasing temperature. The data were analyzed using the POT model. Since the number of heterotrophic bacteria in an open circulating cooling water system should ideally be less than 50 × 10⁷ CFU / L, a threshold of 50 was set. The results are as follows: Figure 4As shown, bacteria in the circulating cooling water system are generally more suited to growing in higher temperature environments. The optimal growth temperature coincides well with the normal operating temperature of the power plant's circulating cooling water. Therefore, 35°C is determined as the optimal temperature for the growth of heterotrophic bacteria in the packing material of the cooling tower in the circulating cooling water system. This temperature is also considered the optimal temperature for the circulation of cooling water into the cooling tower to allow nitrifying bacteria and nitrite bacteria to become the dominant microbial species in the packing material of the circulating cooling water system.

[0094] Table 2A

[0095]

[0096] Table 2B

[0097]

[0098] Table 2C

[0099]

[0100] Table 2D

[0101]

[0102] 1.3. Using the aforementioned indoor simulation device for circulating cooling water systems, a suitable ammonia nitrogen concentration in the makeup water for the growth of heterotrophic bacteria in the packing material of the cooling tower within the circulating cooling water system was determined through a single-factor indoor simulation experiment of makeup water ammonia nitrogen concentration. This concentration is considered the optimal makeup water ammonia nitrogen concentration for achieving the dominance of nitrifying and nitrite-oxidizing bacteria among the microbial populations living in the packing material of the cooling tower within the circulating cooling water system. Specifically:

[0103] Using the aforementioned indoor simulation device for the circulating cooling water system, under the premise that other operating conditions remain unchanged (circulating cooling water temperature entering the cooling tower 35℃, concentration ratio 1, nitrogen-phosphorus ratio 1.0 times that of urban water (i.e., 12.459)), an indoor circulating cooling water system simulation experiment was conducted at different ammonia nitrogen concentrations (1.0-2.5 times the ammonia nitrogen concentration of urban water (ammonia nitrogen concentration of urban water is 4.286 mg / L), with different ammonia nitrogen concentrations taken in 0.5-fold increments). The number of heterotrophic bacteria at sampling points a, b, c, d, and e in the packing material was measured continuously for 5 days (bacterial counting method used was plate counting). The results are shown in Tables 3A, 3B, 3C, and 3D. The maximum number of heterotrophic bacteria measured at each makeup water ammonia nitrogen concentration was also statistically analyzed (e.g., ...). Figure 5 As shown), the POT model is then used to analyze the data (e.g. Figure 6As shown in the figure, the ammonia nitrogen concentration of the makeup water for the growth of heterotrophic bacteria in the packing material of the cooling tower in the circulating cooling water system is determined as the ammonia nitrogen concentration of the makeup water that enables the emergence of nitrifying bacteria and nitrite bacteria as the dominant species in the microbial population living in the packing material of the cooling tower in the circulating cooling water system.

[0104] like Figure 5 As shown, in the single-factor indoor simulation experiment of ammonia nitrogen concentration in makeup water, the maximum number of heterotrophic bacteria first decreased and then increased with increasing ammonia nitrogen concentration. The data were analyzed using the POT model. Since the number of heterotrophic bacteria in an open circulating cooling water system should ideally be less than 50 × 10⁷ CFU / L, a threshold of 50 was set. The results are as follows... Figure 6 As shown, higher ammonia nitrogen concentrations inhibit the growth of heterotrophic bacteria, but at high concentrations, they greatly promote their growth. The appropriate ammonia nitrogen concentration for the makeup water in the cooling tower packing material of a circulating cooling water system was determined to be 1.0 times the ammonia nitrogen concentration of urban water (i.e., 4.286 mg / L), which is considered the optimal concentration for the growth of nitrifying and nitrite-oxidizing bacteria as the dominant microbial species in the cooling tower packing material of the circulating cooling water system.

[0105] Table 3A

[0106]

[0107] Table 3B

[0108]

[0109] Table 3C

[0110]

[0111] Table 3D

[0112]

[0113] 1.4. Using the aforementioned indoor simulation device for circulating cooling water systems, a single-factor indoor simulation experiment with concentration ratio was conducted to determine the appropriate concentration ratio for the growth of heterotrophic bacteria in the packing material of the cooling tower within the circulating cooling water system. This concentration ratio was used to achieve the dominance of nitrifying and nitrite-oxidizing bacteria in the microbial population living in the packing material of the cooling tower within the circulating cooling water system. Specifically:

[0114] Using the aforementioned indoor simulation device for the circulating cooling water system, under the premise that other operating conditions remain unchanged (circulating cooling water temperature entering the cooling tower 35℃, ammonia nitrogen concentration 1.0 times that of urban wastewater (i.e., 4.286 mg / L), and nitrogen-to-phosphorus ratio 1.0 times that of urban wastewater (i.e., 12.459)), an indoor circulating cooling water system simulation experiment was conducted at different concentration ratios (concentration ratios ranging from 1.0 to 2.5 times, with different concentration ratios taken in increments of 0.5 times). The number of heterotrophic bacteria at sampling points a, b, c, d, and e in the packing material was measured for five consecutive days (bacterial counting was performed using the plate count method). The results are shown in Tables 4A, 4B, 4C, and 4D. The maximum number of heterotrophic bacteria measured at each makeup water ammonia nitrogen concentration was also statistically analyzed (e.g., ...). Figure 7 As shown), the POT model is then used to analyze the data (e.g. Figure 8 As shown in the figure, the concentration ratio of heterotrophic bacteria growth in the packing material of the cooling tower in the circulating cooling water system is determined as the concentration ratio at which nitrifying bacteria and nitrite bacteria become the dominant species in the microbial population living in the packing material of the cooling tower in the circulating cooling water system.

[0115] like Figure 7 As shown, in the single-factor indoor simulation experiment of ammonia nitrogen concentration in makeup water, the maximum number of heterotrophic bacteria generally showed a trend of first increasing and then decreasing with the increase of concentration ratio. The POT model was used to analyze the data. Since the number of heterotrophic bacteria in an open circulating cooling water system should be less than 50 × 10⁷ CFU / L, a threshold of 50 was set. The results are as follows: Figure 8 As shown, a higher concentration ratio promotes the growth of heterotrophic bacteria, but at high concentrations, it inhibits their growth. This may be because the high salt concentration in the system leads to excessive osmotic pressure, causing some bacteria to die. Therefore, a concentration ratio of 1.5 was determined to be suitable for the growth of heterotrophic bacteria in the packing material of the cooling tower in the circulating cooling water system. This concentration ratio is considered to be the concentration ratio at which nitrifying bacteria and nitrite bacteria become the dominant microbial species in the packing material of the cooling tower in the circulating cooling water system.

[0116] Table 4A

[0117]

[0118] Table 4B

[0119]

[0120]

[0121] Table 4C

[0122]

[0123] Table 4D

[0124]

[0125] 1.5. Under the conditions of the circulating cooling water temperature entering the cooling tower determined in step 1.2, the ammonia nitrogen concentration of the makeup water determined in step 1.3, and the concentration ratio determined in step 1.4, a single-factor indoor simulation experiment of the makeup water nitrogen-phosphorus ratio is used to determine the suitable makeup water nitrogen-phosphorus ratio for the growth of nitrifying and nitrite-oxidizing bacteria in the packing material of the cooling tower in the circulating cooling water system. This ratio is considered the makeup water nitrogen-phosphorus ratio that enables nitrifying and nitrite-oxidizing bacteria to become the dominant microbial species in the packing material of the cooling tower in the circulating cooling water system. Specifically:

[0126] Using the aforementioned indoor simulation device for a circulating cooling water system, under the premise that other operating conditions remain unchanged (circulating cooling water temperature entering the cooling tower 35℃, ammonia nitrogen concentration 1.0 times that of urban wastewater (i.e., 4.286 mg / L), concentration ratio 1.5 times), an indoor circulating cooling water system simulation experiment was conducted at different nitrogen-to-phosphorus ratios (1.0 times that of urban wastewater (i.e., 12.459:1) and 4.4 times that of urban wastewater (i.e., 54.820:1)). The number of heterotrophic bacteria at sampling points a, b, d, and e in the packing material was measured continuously for 22 days (bacterial counting method: plate counting). The results at a nitrogen-to-phosphorus ratio of 4.4 times that of urban wastewater are shown in Table 5. The maximum number of heterotrophic bacteria measured at each nitrogen-to-phosphorus ratio (e.g., [missing data]) was also statistically analyzed. Figure 9 , Figure 10 , Figure 11 As shown in the figure, the nitrogen-phosphorus ratio of the makeup water for the growth of nitrifying and nitrite-oxidizing bacteria in the packing material of the cooling tower in the circulating cooling water system is determined as the nitrogen-phosphorus ratio of the makeup water that enables the emergence of nitrifying and nitrite-oxidizing bacteria as the dominant species in the microbial population living in the packing material of the cooling tower in the circulating cooling water system.

[0127] Table 5

[0128]

[0129]

[0130] Depend on Figure 9 , Figure 10 , Figure 11It can be seen that a high nitrogen-to-phosphorus ratio has a significant inhibitory effect on the growth of heterotrophic bacteria in the initial and stable phases of system operation. The optimal nitrogen-to-phosphorus ratio for makeup water in cooling tower packing materials for the growth of nitrifying and nitrite-oxidizing bacteria in a circulating cooling water system was determined to be 4.4 times the nitrogen-to-phosphorus ratio of urban runoff (i.e., 54.820:1). This ratio is considered the optimal nitrogen-to-phosphorus ratio for makeup water in cooling tower packing materials to ensure that nitrifying and nitrite-oxidizing bacteria become the dominant microbial species.

[0131] The corrosion rate and microbial slime deposition rate of the pipeline were tested using the hanging plate method. The hanging plates were Type 3 standard corrosion hanging plates for cooling water chemical treatment, made of brass, and measuring 40mm × 13mm × 2mm. The corrosion rate calculation formula is as follows:

[0132]

[0133] In the formula: X is the corrosion rate of the test piece, mm / a; W1 is the weight of the test piece before the test, g; W2 is the weight of the test piece after the test, g; A is the surface area of ​​the test piece, cm². 2 T represents the test time, in hours; D represents the density of the sample material, in g / cm³. 2 .

[0134] Ultimately, when the nitrogen-to-phosphorus ratio was 1.0 times that of urban runoff, the corrosion rate was 0.005099 mm / a, and the annual microbial slime deposition was 0.6376 g / cm³. 2 When the nitrogen-to-phosphorus ratio is 4.4 times that of urban runoff, the corrosion rate is 0.004478 mm / a, and the annual deposition of microbial slime is 0.4689 g / cm³. 2 Therefore, directly reusing greywater for power plant circulating cooling water is not conducive to the treatment of system corrosion and scaling problems.

[0135] In an indoor circulating cooling water system simulation experiment conducted when the nitrogen-to-phosphorus ratio was 4.4 times that of urban runoff, changes in ammonia nitrogen concentration and total phosphorus concentration in the circulating water were measured. The results are as follows: Figure 12 , Figure 13 As shown. By Figure 12 , Figure 13 It can be seen that due to the absorption and fixation of ammonia nitrogen and phosphorus in the water by nitrifying and nitrite-oxidizing bacteria, the ammonia nitrogen and phosphorus contents in the circulating water decrease significantly over time, with an average daily reduction of 0.597 mg / (L·d) for ammonia nitrogen concentration and 0.063 mg / (L·d) for total phosphorus concentration. Therefore, by balancing the fixation of ammonia nitrogen by microorganisms in the system with the increase in ammonia nitrogen introduced by makeup water, the ammonia nitrogen concentration in the system can be kept stable below 6 mg / L in the long term, thereby mitigating system corrosion.

[0136] Depend on Figures 9 to 13It can be seen that a high nitrogen-phosphorus ratio has a significant inhibitory effect on the growth of heterotrophic bacteria in the early and stable phases of system operation.

[0137] In an indoor circulating cooling water system simulation experiment conducted at nitrogen-to-phosphorus ratios of 4.4 times (high nitrogen-to-phosphorus ratio) and 1.0 times (standard nitrogen-to-phosphorus ratio) of urban water, high-throughput sequencing was performed on samples taken from sampling points a, b, d, and e in the packing material. Specifically, to understand the growth of nitrifying and nitrite-oxidizing bacteria in the packing material, five groups of microbial samples were sent for testing. These were: sampling point B on day 3 (high nitrogen-to-phosphorus ratio), denoted as 3_b; sampling points A and B on day 22 (high nitrogen-to-phosphorus ratio), denoted as 22_a and 22_b; and sampling points A and B on day 22 (standard nitrogen-to-phosphorus ratio), denoted as 22_A and 22_B.

[0138] Analyze OUT data (e.g.) Figure 14 As shown in the figure, the total number of species gradually increases with the increase of sample size; (e.g.) Figure 15 As shown in the figure, the number of core species gradually increases with the increase of sample size; (e.g.) Figure 16 The curve (as shown) tends to flatten out, indicating that there are sufficient samples in this sequencing and that the samples can represent the true composition of the samples.

[0139] Through community composition analysis (e.g.) Figure 17 As shown in the image, nitrifying bacteria were the dominant bacterial species in the sample, accounting for the largest proportion. The content of nitrifying bacteria was even higher under high nitrogen-to-phosphorus ratios.

[0140] 2. Adjust the ammonia nitrogen concentration of the urban water to the ammonia nitrogen concentration of the makeup water determined in step 1, and adjust the nitrogen-phosphorus ratio of the urban water to the nitrogen-phosphorus ratio of the makeup water determined in step 1 to obtain the makeup water for the circulating cooling water system.

[0141] 3. Determine the amount of water to add based on the concentration ratio determined in step 1.

[0142] 4. Use the water replenishment water obtained in step 2 as the replenishment water for the circulating cooling water system and replenish the circulating cooling water system according to the replenishment water volume determined in step 3. At the same time, control the temperature of the circulating cooling water in the circulating cooling water system to the temperature determined in step 1.

[0143] The ammonia nitrogen concentration of the circulating cooling water in the circulating cooling water system is monitored in real time. When the ammonia nitrogen concentration exceeds the ammonia nitrogen concentration threshold, pure water is used to replace the water replenishment water obtained in step 2 as the water replenishment water for the circulating cooling water system. The water replenishment water for the circulating cooling water system is carried out according to the water replenishment amount determined in step 3 until the ammonia nitrogen concentration of the circulating cooling water in the cooling water system is lower than 6 mg / L.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Modifications and equivalent substitutions can be made without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for makeup water in a power plant circulating cooling water system, the method comprising: 1) Determine the ammonia nitrogen concentration in the makeup water, the nitrogen-to-phosphorus ratio in the makeup water, the concentration ratio, and the temperature of the circulating cooling water entering the cooling tower to achieve the emergence of nitrifying bacteria and nitrite bacteria as the dominant microbial species in the packing material of the cooling tower in the circulating cooling water system. 2) Adjust the ammonia nitrogen concentration of the urban water to the ammonia nitrogen concentration of the makeup water determined in step 1), and adjust the nitrogen-phosphorus ratio of the urban water to the nitrogen-phosphorus ratio of the makeup water determined in step 1) to obtain the makeup water for the circulating cooling water system. 3) Determine the amount of water to add based on the concentration ratio determined in step 1); 4) Use the water replenishment water obtained in step 2) to replenish the circulating cooling water system according to the replenishment water volume determined in step 3), and at the same time control the temperature of the circulating cooling water in the circulating cooling water system to the temperature determined in step 1). The method also includes real-time monitoring of the ammonia nitrogen concentration of the circulating cooling water in the circulating cooling water system. When the ammonia nitrogen concentration exceeds the ammonia nitrogen concentration threshold, pure water is used to replace the water replenishment water in the circulating cooling water system obtained in step 2) as the water replenishment water for the circulating cooling water system. The water replenishment water is carried out according to the water replenishment amount determined in step 3) until the ammonia nitrogen concentration of the circulating cooling water in the cooling water system is lower than the ammonia nitrogen concentration threshold. In step 1), the concentration of ammonia nitrogen in the makeup water, the nitrogen-to-phosphorus ratio in the makeup water, the concentration ratio, and the temperature of the circulating cooling water entering the cooling tower are determined through indoor simulation experiments to achieve the dominance of nitrifying and nitrite-oxidizing bacteria in the packing material of the cooling tower within the circulating cooling water system. This determination includes: A. The temperature of the circulating cooling water entering the cooling tower is determined by a single-factor indoor simulation experiment to determine the optimal temperature for the growth of heterotrophic bacteria in the packing material of the cooling tower in a circulating cooling water system. This temperature is considered the optimal temperature for the growth of nitrifying bacteria and nitrite bacteria in the packing material of the cooling tower in a circulating cooling water system. B. The appropriate ammonia nitrogen concentration in the make-up water for the growth of heterotrophic bacteria in the packing material of the cooling tower in a circulating cooling water system was determined by a single-factor indoor simulation experiment on the ammonia nitrogen concentration in the make-up water. This concentration is used to determine the ammonia nitrogen concentration in the make-up water that enables nitrifying bacteria and nitrite bacteria to become the dominant microbial species in the packing material of the cooling tower in a circulating cooling water system. C. The concentration ratio suitable for the growth of heterotrophic bacteria in the packing material of the cooling tower in the circulating cooling water system was determined by a single-factor indoor simulation experiment of concentration ratio. This concentration ratio is used to determine the microbial population in the packing material of the cooling tower in the circulating cooling water system where nitrifying bacteria and nitrite bacteria become the dominant species. D. Under the conditions of the circulating cooling water temperature entering the cooling tower determined in step A, the ammonia nitrogen concentration of the makeup water determined in step B, and the concentration ratio determined in step C, the suitable makeup water nitrogen-phosphorus ratio for the growth of nitrifying and nitrite-oxidizing bacteria in the packing material of the cooling tower in the circulating cooling water system is determined by a single-factor indoor simulation experiment of the makeup water nitrogen-phosphorus ratio. This ratio is used to determine the makeup water nitrogen-phosphorus ratio that enables the emergence of nitrifying and nitrite-oxidizing bacteria as the dominant species in the microbial population living in the packing material of the cooling tower in the circulating cooling water system. The ammonia nitrogen concentration threshold is 6 mg / L.

2. The water replenishment method according to claim 1, wherein, In step 2), when the ammonia nitrogen concentration of the replenished water is higher than that of the urban water and the nitrogen-phosphorus ratio of the replenished water is higher than that of the urban water, the ammonia nitrogen concentration and nitrogen-phosphorus ratio of the urban water are increased by adding ammonium chloride to the urban water.

3. The water replenishment method according to claim 1, wherein, Step 1) In determining the ammonia nitrogen concentration in the makeup water, the nitrogen-to-phosphorus ratio in the makeup water, the concentration ratio, and the temperature of the circulating cooling water entering the cooling tower to achieve the emergence of nitrifying bacteria and nitrite-oxidizing bacteria as the dominant microbial populations in the packing material of the cooling tower in the circulating cooling water system, the ammonia nitrogen concentration in the makeup water is determined to be within the range of 1.0 to 2.5 times the ammonia nitrogen concentration of urban wastewater, the nitrogen-to-phosphorus ratio in the makeup water is determined to be within the range of 1.0 to 2.5 times the nitrogen-to-phosphorus ratio of urban wastewater, the concentration ratio is determined to be within the range of 1.0 to 2.5, and the temperature is determined to be within the range of 25℃ to 40℃.

4. The water replenishment method according to claim 1, wherein, The determination of the makeup water ammonia nitrogen concentration, makeup water nitrogen-to-phosphorus ratio, concentration ratio, and circulating cooling water temperature entering the cooling tower, which enable the microbial population living in the packing material of the cooling tower to become dominated by nitrifying bacteria and nitrite bacteria, also includes: Before proceeding with steps A, B, and C, orthogonal indoor simulation experiments were conducted to determine the possible range of circulating cooling water temperature, makeup water ammonia nitrogen concentration, and concentration ratio suitable for the growth of heterotrophic bacteria in the packing material of the cooling tower in a circulating cooling water system. The possible ranges of the circulating cooling water temperature, makeup water ammonia nitrogen concentration, and concentration ratio entering the cooling tower for the growth of heterotrophic bacteria in the packing material of the cooling tower in the determined suitable circulating cooling water system are used as the experimental research ranges of the circulating cooling water temperature, makeup water ammonia nitrogen concentration, and concentration ratio entering the cooling tower in the single-factor experiments of steps A, B, and C, respectively.

5. The water replenishment method according to claim 1, wherein, The indoor simulation experiment was conducted using an indoor simulation device for a circulating cooling water system; the indoor simulation device for the circulating cooling water system included: a cooling tower, an automatic water replenishment device for an ammonia nitrogen detector, a thermometer, a flow meter, a circulating water pump, and heating equipment; wherein... The cooling tower has a cold water pool, a makeup water inlet, a circulating water inlet, and a circulating water outlet at its bottom. Inside the cooling tower, there is a packing zone and a spray system. The makeup water inlet and the circulating water inlet are connected to the inlet of the spray system, and the outlet of the spray system is equipped with nozzles positioned above the packing zone. The circulating water outlet is connected to the cold water pool. This allows the makeup water and circulating water entering the cooling tower to be sprayed into the packing zone, treated, and then enter the cold water pool. Water in the cold water pool is discharged from the cooling tower through the circulating water outlet. The cooling tower also has an air inlet and outlet. The ammonia nitrogen detector's automatic water replenishment device is installed in the cooling tower's cold water pool and connected to the cooling tower's replenishment water inlet. The automatic water replenishment device is used to monitor the ammonia nitrogen concentration of the circulating cooling water in the cold water pool in real time and control the replenishment of water to the indoor simulation device of the circulating cooling water system. The cooling tower's circulating water outlet is connected to the heating equipment's water inlet through a circulating water pipeline, and the heating equipment's water outlet is connected to the cooling tower's circulating water inlet through a circulating water pipeline. The circulating water pump, flow meter, and thermometer are installed on the circulating water pipeline.

6. The water replenishment method according to claim 5, wherein, The number of circulating water pumps, flow meters, and thermometers shall not be less than two. Circulating water pumps, flow meters, and thermometers shall be installed on the circulating water pipeline between the circulating water outlet of the cooling tower and the water inlet of the heating equipment, and circulating water pumps, flow meters, and thermometers shall be installed on the circulating water pipeline between the water outlet of the heating equipment and the circulating water inlet of the cooling tower.

7. The water replenishment method according to claim 5, wherein, The packing area shall have at least 5 sampling points, including the upper sampling point of the central axis of the packing area, the middle sampling point of the central axis, the lower sampling point of the central axis, the left sampling point of the packing area, and the right sampling point of the packing area.

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