Thermal power plant low-level waste heat and desulfurization oxidation wind coupled high-salinity wastewater concentration treatment system and method

Abstract

The invention relates to the technical field of wastewater concentration treatment, in particular to a thermal power plant low-level waste heat and desulfurization oxidation wind coupled high-salinity wastewater concentration treatment system and method. According to the invention, water in the high-salinity wastewater is separated out through air carrying in a mode of increasing air temperature by utilizing the temperature dependence of vapor pressure of saturated water, then the water carried by high-temperature air is condensed and recycled by utilizing heat exchange and spraying cardinal numbers, and meanwhile, the heat absorbed by the heat exchanger can be recycled through the water to realize zero loss, so that the system is energy-saving and environment-friendly. A large amount of wind can also be used in the desulfurization slurry tower as oxidation wind, so that zero loss of the wind is realized; by means of the design, the demand of the oxidation fan can be met, and the working efficiency of follow-up operation can be improved; due to selection of low-level waste heat, factory loss can be reduced, the application range is widened, economic benefits are improved, efficient operation of wastewater concentration operation is achieved, and the problem of low-level waste heat resource conversion and utilization in a thermal power plant is efficiently solved.

Description

Technical Field

[0001] This invention relates to the field of wastewater concentration and treatment technology, and more specifically, to a high-salt wastewater concentration and treatment system and method that couples low-grade waste heat from thermal power plants with desulfurization oxidation air. Background Technology

[0002] High-salinity wastewater contains a wide variety of toxic and harmful substances. High concentrations of salt and chloride ions can easily cause equipment corrosion and scaling in subsequent processes (such as reverse osmosis and evaporation crystallization), and may even lead to membrane fouling and reduced heat exchange efficiency, significantly increasing the difficulty and cost of subsequent treatment. Nitrogenous pollutants may also enter the water body, and high-hardness water can easily cause calcium and magnesium salt crystallization, clogging equipment such as membrane distillation or evaporators. After years of research and treatment, various methods for concentrating high-salinity wastewater have been developed, but the problems of poor system stability and high operating costs remain unresolved.

[0003] It can be said that there are few reports on the technology of using air to carry water to concentrate high-salt wastewater. This is because the design of this process requires the comprehensive recovery of various aspects of thermal power plant low-temperature waste heat, water, steam, and gas. At the same time, the overall system needs to balance various temperatures to prevent scaling. There is a lack of a technical route that can take into account energy consumption, treatment efficiency, and operating costs.

[0004] For example, the utility model patent CN213060260U, entitled "A Coupled Evaporation and Concentration Wastewater Treatment System," utilizes the waste heat from the steam turbine condensate or the low-grade heat energy of the condensate to couple air or flue gas into an empty tower for spray evaporation and concentration. This can increase the output of the empty tower evaporation and concentration tower, reduce the flow area and volume of the evaporation and concentration tower, as well as the capacity of the auxiliary equipment, thereby reducing the energy consumption and operating costs of wastewater concentration. However, it is clear that this scheme only utilizes the waste heat from the steam turbine condensate or the low-grade heat energy of the condensate for the concentration operation, while the issue of the heat energy source that the steam turbine itself should use remains unresolved. Therefore, it can be said that this scheme still suffers from the problem of failing to balance energy consumption and high operating costs. Summary of the Invention

[0005] In view of the above-mentioned problems in the existing technology, the purpose of this invention is to provide a high-salt wastewater concentration and treatment system and method that couples low-grade waste heat from thermal power plants with desulfurization oxidation air.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows: A high-salt wastewater concentration and treatment system coupling low-grade waste heat from a thermal power plant with desulfurization oxidation air, the system comprising an evaporator, a wastewater inlet unit, a wastewater outlet unit, a fresh air preheating unit, a fresh air heating unit, and a desulfurization slurry tower; The wastewater inlet unit includes a spray pump installed inside the evaporator, which can transport wastewater into the evaporator and perform spraying operations. The wastewater discharge unit includes a discharge pump connected to the outlet of the evaporator, through which concentrated wastewater can be transported to external equipment; The fresh air preheating unit includes a first fan connected to the air outlet of the evaporator. The first fan can introduce external fresh air and make the external fresh air merge with the humid air flowing out of the air outlet of the evaporator. The fresh air heating unit includes a second fan whose air inlet is connected to the first air outlet of the first fan, and the second air outlet of the second fan is also connected to the evaporator. The first air outlet of the first fan is simultaneously connected to the desulfurization slurry tower; The hot water generated by the flue gas cooler in front of the desulfurization slurry tower flows through the pipeline connecting the second fan and the evaporator; The temperature of the hot coal water is less than 100°C.

[0007] Furthermore, the outlet of the discharge pump is connected to the evaporator.

[0008] Furthermore, the evaporator includes a lower spray section and an upper spray section, the second fan is connected to the lower spray section, and the outlet pump is connected to the upper spray section.

[0009] Furthermore, the pipeline connecting the second fan and the evaporator can also be supplemented with external steam for heating.

[0010] A method for treating high-salinity wastewater from a thermal power plant using a coupled system of low-grade waste heat and desulfurization oxidation air, the method comprising the following steps: (1) Wastewater is transported to the evaporator by the spray pump, while the first fan introduces fresh air from outside and delivers it to the second fan; (2) The second fan continuously delivers fresh air to the evaporator, and during the delivery process, the heat transfer water generated by the desulfurization slurry tower heats the fresh air through the delivery pipeline. (3) The fresh air that arrives at the evaporator sprays the wastewater that arrives at the evaporator at the same time. The wastewater and the high-temperature fresh air undergo heat and mass transfer reactions. As the water in the wastewater continues to evaporate, the wastewater is concentrated. (4) The wastewater after concentration treatment is discharged from the evaporator through the discharge pump. If the concentration ratio of the discharged wastewater does not meet the requirements, it is returned to the evaporator for secondary spray treatment. If the requirements are met, the concentrated wastewater and sludge are obtained through the separator. The concentrated wastewater is used for external equipment. (5) During the wastewater concentration reaction in the evaporator, the heated air in the evaporator is transported to the first fan through the air outlet. During the transport process, the air is continuously cooled down, the water condenses and precipitates, the air humidity decreases and part of it is transported to the desulfurization slurry tower through the first fan as oxidation air. (6) The fresh air introduced again by the first fan and the air that has been cooled and condensed in step (5) are combined and transported to the second fan. The second fan continues to transport the combined fresh air and air to the evaporator to complete the cycle.

[0011] Furthermore, during the process of the second fan delivering fresh air / fresh air and air to the evaporator, an external steam is provided to supplement the heating of the delivery pipeline.

[0012] A logical operation method for a high-salinity wastewater concentration and treatment system coupled with desulfurization oxidation air from a thermal power plant, the method comprising the following steps: (1) Calculate the temperature required for the operation of the evaporator based on the wastewater treatment volume. If the temperature meets the requirements, perform circulating spray concentration operation. If not, continuously heat the fresh air with the hot coal water generated by the desulfurization slurry tower in the slurry desulfurization treatment until the temperature meets the requirements. (2) After completing the circulating spray concentration operation, check whether the concentration ratio of the wastewater meets the requirements. If it does not meet the requirements, the treated wastewater is reintroduced into the evaporator for circulating spray concentration operation until the concentration ratio meets the requirements. If it does meet the requirements, the treated concentrated wastewater is discharged. (3) After meeting the requirements for concentration ratio in step (2), the air heated in the evaporator is simultaneously transported to the desulfurization slurry tower through the first fan. The air volume is checked to see if it meets the requirements for oxidation air in slurry desulfurization operation. If it does, the desulfurization slurry tower starts slurry desulfurization treatment. If it does not meet the requirements, the air is continuously introduced until the air volume meets the requirements.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes the temperature dependence of saturated water vapor pressure to separate water from high-salt wastewater by increasing the air temperature. Then, using heat exchange and spraying, the water carried by the high-temperature air is condensed and recovered. At the same time, the heat absorbed by the heat exchanger can be recycled through water recovery to achieve zero loss. A large amount of air can also be used as oxidation air in the desulfurization slurry tower, thereby achieving zero loss of air.

[0014] The above design not only solves the demand for oxidation blowers, but also improves the efficiency of subsequent operations; the selection of low-grade waste heat can also save plant losses, expand the scope of application, improve economic benefits, and realize the efficient operation of wastewater concentration, thus efficiently solving the problem of low-grade waste heat resource conversion and utilization in thermal power plants. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the module structure of the processing system described in this invention; Figure 2 This is a flowchart illustrating the steps of the logical operation method described in this invention. In the diagram: 1-Evaporator; 1-2-Lower spray section; 1-3-Upper spray section; 1-4-Air outlet; 2-Wastewater inlet unit; 2-1-Spray pump; 3-Wastewater discharge unit; 3-1-Discharge pump; 3-2-Outlet; 3-3-Separator; 4-Fresh air preheating unit; 4-1-First fan; 4-2-First air outlet; 5-Fresh air heating unit; 5-1-Second fan; 5-2-Air inlet; 5-3-Second air outlet; 6-Desulfurization slurry tower. Detailed Implementation

[0016] The present invention will be further described below with reference to specific embodiments.

[0017] The high-salt wastewater concentration and treatment system of thermal power plant low-grade waste heat coupled with desulfurization oxidation air according to the present invention includes an evaporator 1, a wastewater inlet unit 2, a wastewater outlet unit 3, a fresh air preheating unit 4, a fresh air heating unit 5, and a desulfurization slurry tower 6.

[0018] First, describe the overall system structure, such as... Figure 1 As shown, the wastewater inlet unit 2 includes a spray pump 2-1 installed in the evaporator 1. The spray pump 2-1 can transport wastewater into the evaporator 1 for subsequent spraying and concentration operations.

[0019] The wastewater discharge unit 3 includes a discharge pump 3-1 connected to the outlet of the evaporator 1. The discharge pump 3-1 can transport the concentrated wastewater after the spray concentration operation to external equipment. At the same time, the outlet 3-2 of the discharge pump 3-1 is also connected to the evaporator 1, which means that the concentrated wastewater after the spray concentration operation can be reintroduced into the evaporator 1. The discharge pump 3-1 is also connected to a separator 3-3, which can separate the concentrated wastewater and the sludge.

[0020] Based on this, it can be seen that the evaporator 1 includes a lower spray section 1-2 and an upper spray section 1-3. The spray pump 2-1 is located in the lower spray section 1-2, while the outlet pump 3-1 is connected to the upper spray section 1-3, thereby realizing the re-spraying and concentration of wastewater.

[0021] The fresh air preheating unit 4 includes a first fan 4-1 connected to the air outlet 1-4 of the evaporator 1. The first fan 4-1 can introduce external fresh air and make the introduced external fresh air merge with the humid air flowing out from the air outlet 1-4 of the evaporator 1.

[0022] The fresh air heating unit 5 includes a second fan 5-1 connected to the first air outlet 4-2 of the first fan 4-1 via an air inlet 5-2. The second air outlet 5-3 of the second fan 5-1 is also connected to the evaporator 1. The first air outlet 4-2 of the first fan 4-1 is also connected to the desulfurization slurry tower 6. Meanwhile, the hot water generated by the flue gas cooler in front of the desulfurization slurry tower 6 flows through the pipeline connecting the second fan 5-1 and the evaporator 1. In other words, during the process of fresh air and air being transported into the evaporator 1 by the action of the second fan 5-1, they will be heated by the hot water generated by the desulfurization slurry tower 6.

[0023] This completes the structural design of the entire high-salt wastewater concentration and treatment system described in this invention. First, external fresh air (ambient air) is introduced into the system. This fresh air is preheated by the humid air flowing from the outlet 1-3 of the evaporator 1. Then, the fresh air and ambient air enter the fresh air heating unit 5 and, under the action of the second fan 5-1, are transported into the evaporator 1. During this process, the heat transfer medium water is heated, forming high-temperature unsaturated air. Upon reaching the evaporator 1, the high-temperature unsaturated air comes into contact with the wastewater. Some of the moisture in the wastewater is evaporated and carried away by the heated air, thus concentrating the wastewater. At this point, the air becomes high-humidity air. The high-humidity air is then transported to the first fan 4-1 through the outlet 1-3 of the evaporator 1. During the transport process, it is cooled down, the moisture condenses and precipitates out, the humidity decreases, and saturated humid air is formed. Part of it is combined with the fresh air introduced by the first fan 4-1 and transported to the second fan 5-1 for heating and then for wastewater concentration. The other part is directly reused in the desulfurization slurry tower 6 as the oxidation air for slurry desulfurization.

[0024] The clean water formed by the condensation of high-humidity air during the cooling process can be directly discharged from the first fan 4-1 through a separately installed water pump and used as process makeup water.

[0025] The above mainly describes the air / fresh air circulation process. In addition, there is also the wastewater circulation process.

[0026] During the spraying and concentration process of wastewater in the thermal power plant, the wastewater undergoes heat and mass transfer reactions with the air. As the water in the wastewater continues to evaporate, the wastewater is concentrated. The concentrated wastewater is then transported to other equipment in the plant via the discharge pump 3-1 for other uses, such as coal yard spraying, dry steaming towers, etc. This further improves the utilization rate of air and wastewater, increases the working efficiency of equipment, and reduces cost losses.

[0027] Thirdly, there is the recycling of the heat source. In this scheme, the high-temperature heat transfer water generated by the flue gas before desulfurization in the desulfurization slurry tower 6 is used as the driving heat source for the wastewater concentration process, heating the fresh air and general air. Simultaneously, the urea hydrolysis process allows the condensate from the steam tracing process to serve as an auxiliary heat source. After heating the wastewater, the high-temperature heat transfer water and steam condensate cool down. The heat transfer water can be returned to the flue gas heat exchanger before desulfurization for recycling, while the steam condensate, after cooling, can be transported to the steam condensate tank. This fully utilizes the heat generated during the desulfurization process, achieving almost zero heat loss and significantly reducing treatment costs.

[0028] Furthermore, the following advantages exist during the implementation of this plan: The first requirement is the air volume and air pressure of the first fan 4-1 and the second fan 5-1. The air volume needs to meet the needs of wastewater concentration and heat exchange, and the air pressure after passing through evaporator 1 should meet the air pressure requirements of the oxidation air during slurry desulfurization. This design can not only solve the demand of oxidation air in the desulfurization slurry tower, but also facilitate the efficiency of the water and heat carried by the subsequent air to be utilized by the desulfurization tower.

[0029] The second aspect is the selection of low-grade waste heat. This solution utilizes the unused low-grade waste heat within the plant as a heat source. Without increasing energy consumption, heat can be recovered. For example, the condensate, heat transfer water, and boiler drainage from various systems within the thermal power plant can all be used. The temperature of the heat transfer water should be less than 100℃, which can greatly reduce plant losses, expand the applicability of the solution, effectively improve the plant's economic benefits, and reduce environmental pollution hazards.

[0030] The third is the selection of air temperature. Since the ability of air to carry water vapor is strongly dependent on temperature and increases exponentially with increasing temperature, by combining the temperature of low-grade waste heat mentioned above, by selecting a suitable air temperature, the dry water in the wastewater can be converted into saturated water vapor through efficient air-water heat exchange and carried by the wind to the subsequent units.

[0031] Fourthly, in terms of energy consumption, the main energy consumption of this scheme is only the power consumption of the fan and the energy consumption of low-grade waste heat. However, the power consumption of the fan is almost equal to the power consumption of the oxidation fan in the desulfurization slurry tower 6, and the heat consumption of low-grade waste heat will eventually enter the desulfurization slurry tower 6 with the wind, so the heat consumption is almost negligible.

[0032] In summary, the treatment method of the high-salinity wastewater concentration system coupled with desulfurization oxidation air in thermal power plants according to the present invention includes the following steps: (1) Wastewater is transported to the evaporator by a spray pump, while the first fan introduces fresh air from outside and delivers it to the second fan; (2) The second fan continuously delivers fresh air to the evaporator, and during the delivery process, the heat transfer water generated by the desulfurization slurry tower heats the fresh air through the delivery pipeline. (3) The fresh air that arrives at the evaporator sprays the wastewater that arrives at the evaporator at the same time. The wastewater and the high-temperature fresh air undergo heat and mass transfer reactions. As the water in the wastewater continues to evaporate, the wastewater is concentrated. (4) The wastewater after concentration treatment is discharged from the evaporator through the discharge pump. If the concentration ratio of the discharged wastewater does not meet the requirements, it is returned to the evaporator for secondary spray treatment. If the requirements are met, the concentrated wastewater and sludge are obtained through the separator. The concentrated wastewater is used for external equipment. (5) During the wastewater concentration reaction in the evaporator, the heated air in the evaporator is transported to the first blower through the air outlet. During the transport process, the air is continuously cooled down, the water condenses and precipitates, the air humidity decreases and part of it is transported to the desulfurization slurry tower through the first blower as oxidation air. (6) The fresh air introduced by the first fan and the air that has been cooled and condensed in step (5) are combined and transported to the second fan. The second fan continues to transport the combined fresh air and air to the evaporator to complete the cycle.

[0033] like Figure 2 As shown, the logical operation method of the high-salinity wastewater concentration and treatment system coupled with desulfurization oxidation air in thermal power plants according to the present invention includes the following steps: (1) Calculate the temperature required for the operation of the evaporator based on the amount of wastewater treated. If the temperature meets the requirements, then carry out the circulating spray concentration operation. If it does not meet the requirements, then continuously heat the fresh air by the hot coal water generated by the desulfurization slurry tower in the slurry desulfurization treatment until the temperature meets the requirements. (2) After completing the circulating spray concentration operation, check whether the concentration ratio of the wastewater meets the requirements. If it does not meet the requirements, the treated wastewater is reintroduced into the evaporator for circulating spray concentration operation until the concentration ratio meets the requirements. If it does meet the requirements, the treated concentrated wastewater is discharged. (3) After meeting the requirements for concentration ratio in step (2), the air heated in the evaporator is simultaneously transported to the desulfurization slurry tower through the first fan. The air volume is checked to see if it meets the requirements for oxidation air as slurry desulfurization operation. If it does, the desulfurization slurry tower starts slurry desulfurization treatment. If it does not meet the requirements, air is continuously introduced until the air volume meets the requirements.

[0034] Compared with existing technologies, the processing system, method, and logic operation method adopted in this invention can achieve coupling with the desulfurization oxidation fan and evaporator by simply adjusting the air inlet flow and pressure of the fan, thus achieving zero air loss. At the same time, it can achieve efficient operation of wastewater concentration by simply adjusting the operating parameters such as water inlet volume, duration, air volume, and waste heat utilization during the wastewater concentration process, thus efficiently solving the problem of low-grade waste heat resource conversion and utilization in thermal power plants.

[0035] The beneficial effects are described below with reference to the embodiments.

[0036] The total dissolved solids (TDS) of wastewater from a power plant is approximately 30,000 mg / L, with a chloride ion concentration of approximately 20,000 mg / L. This wastewater is a recurring wastewater, and conventional processes such as MVR, flash evaporation, SCR, and DTRO are used for concentration. However, these processes have high operating costs and a high risk of scaling.

[0037] This plant utilizes the high-salt wastewater concentration treatment method proposed in this invention, employing a technology that couples low-grade waste heat with desulfurization oxidation air to establish a complete treatment system, and applying intelligent control logic to achieve energy-saving operation. Since its commissioning a year ago, the system has significantly improved the efficiency of desulfurization wastewater concentration, demonstrating outstanding treatment benefits. Specifically, the system is designed with a high-temperature heat transfer medium flow rate of 300-350 t / h, an inlet water temperature of 90-95℃, and an outlet water temperature of 72℃. The designed steam condensate flow rate is 10 t / h, with an inlet water temperature of 100℃ and an outlet water temperature of 72℃. The system is designed with a blower with a capacity of Q=150000 Nm. 3 The system operates continuously at a pressure of 30000 Pa and a temperature of / h. Due to the use of both air-to-air and air-to-water heat exchange, no structural problems occurred throughout the process. After the air enters the desulfurization slurry tower, it effectively reduces the oxidation fan's power consumption by approximately 150 kWh, saves 2.5 t / h of water in the desulfurization slurry tower, and increases the desulfurization wastewater concentration rate by 5 times. When the wastewater concentration system, which couples the low-grade waste heat utilization with the desulfurization oxidation air, is put into operation, it operates automatically according to intelligent control logic. Even with fluctuations in influent water quality, the system maintains stable operation. By comprehensively considering power and heat consumption, the system operates in the most economical way, with an overall wastewater treatment cost of approximately 25 yuan / ton, demonstrating a significant economic advantage compared to other processes.

Claims

1. A high-salinity wastewater concentration and treatment system coupling low-grade waste heat from thermal power plants with desulfurization oxidation air, characterized in that, The system includes an evaporator, a wastewater inlet unit, a wastewater outlet unit, a fresh air preheating unit, a fresh air heating unit, and a desulfurization slurry tower; The wastewater inlet unit includes a spray pump installed inside the evaporator, which can transport wastewater into the evaporator and perform spraying operations. The wastewater discharge unit includes a discharge pump connected to the outlet of the evaporator, through which concentrated wastewater can be transported to external equipment; The fresh air preheating unit includes a first fan connected to the air outlet of the evaporator. The first fan can introduce external fresh air and make the external fresh air merge with the humid air flowing out of the air outlet of the evaporator. The fresh air heating unit includes a second fan whose air inlet is connected to the first air outlet of the first fan, and the second air outlet of the second fan is also connected to the evaporator. The first air outlet of the first fan is simultaneously connected to the desulfurization slurry tower; The hot water generated by the flue gas cooler in front of the desulfurization slurry tower flows through the pipeline connecting the second fan and the evaporator; The temperature of the hot coal water is less than 100°C.

2. The high-salinity wastewater concentration and treatment system of the thermal power plant low-grade waste heat coupled with desulfurization oxidation air according to claim 1, characterized in that, The outlet of the discharge pump is connected to the evaporator.

3. The high-salinity wastewater concentration and treatment system of the thermal power plant low-grade waste heat coupled with desulfurization oxidation air according to claim 2, characterized in that, The evaporator includes a lower spray section and an upper spray section, the second fan is connected to the lower spray section, and the outlet pump is connected to the upper spray section.

4. The high-salinity wastewater concentration and treatment system of thermal power plant low-grade waste heat coupled with desulfurization oxidation air according to claim 1, characterized in that, The pipe connecting the second fan and the evaporator can also be supplemented with external steam for heating.

5. A treatment method for a high-salinity wastewater concentration and treatment system coupled with desulfurization oxidation air from a thermal power plant according to any one of claims 1-4, characterized in that, The method includes the following steps: (1) Wastewater is transported to the evaporator by the spray pump, while the first fan introduces fresh air from outside and delivers it to the second fan; (2) The second fan continuously delivers fresh air to the evaporator, and during the delivery process, the heat transfer water generated by the desulfurization slurry tower heats the fresh air through the delivery pipeline. (3) The fresh air that arrives at the evaporator sprays the wastewater that arrives at the evaporator at the same time. The wastewater and the high-temperature fresh air undergo heat and mass transfer reactions. As the water in the wastewater continues to evaporate, the wastewater is concentrated. (4) The wastewater after concentration treatment is discharged from the evaporator through the discharge pump. If the concentration ratio of the discharged wastewater does not meet the requirements, it is returned to the evaporator for secondary spray treatment. If the requirements are met, the concentrated wastewater and sludge are obtained through the separator. The concentrated wastewater is used for external equipment. (5) During the wastewater concentration reaction in the evaporator, the heated air in the evaporator is transported to the first fan through the air outlet. During the transport process, the air is continuously cooled down, the water condenses and precipitates, the air humidity decreases and part of it is transported to the desulfurization slurry tower through the first fan as oxidation air. (6) The fresh air introduced again by the first fan and the air that has been cooled and condensed in step (5) are combined and transported to the second fan. The second fan continues to transport the combined fresh air and air to the evaporator to complete the cycle.

6. The method for concentrating and treating high-salinity wastewater from thermal power plants by coupling low-grade waste heat with desulfurization oxidation air according to claim 5, characterized in that, During the process of the second fan delivering fresh air / fresh air and air to the evaporator, an external steam is provided to supplement the heating of the delivery pipeline.

7. A logical operation method for a high-salinity wastewater concentration and treatment system coupled with desulfurization oxidation air in a thermal power plant according to any one of claims 1-4, characterized in that, The method includes the following steps: (1) Calculate the temperature required for the operation of the evaporator based on the wastewater treatment volume. If the temperature meets the requirements, perform circulating spray concentration operation. If not, continuously heat the fresh air with the hot coal water generated by the desulfurization slurry tower in the slurry desulfurization treatment until the temperature meets the requirements. (2) After completing the circulating spray concentration operation, check whether the concentration ratio of the wastewater meets the requirements. If it does not meet the requirements, the treated wastewater is reintroduced into the evaporator for circulating spray concentration operation until the concentration ratio meets the requirements. If it does meet the requirements, the treated concentrated wastewater is discharged. (3) After meeting the requirements for concentration ratio in step (2), the air heated in the evaporator is simultaneously transported to the desulfurization slurry tower through the first fan. The air volume is checked to see if it meets the requirements for oxidation air in slurry desulfurization operation. If it does, the desulfurization slurry tower starts slurry desulfurization treatment. If it does not meet the requirements, the air is continuously introduced until the air volume meets the requirements.

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