Evaporation zero-emission system and control method thereof

Abstract

The invention discloses an evaporation zero-emission system and a control method thereof. The method comprises the following steps: driving a cooling medium to circularly flow between a heat exchanger and a cooling coil through a circulating pump; heat exchange between the cooling medium and drainage of the converter valve is realized through the heat exchanger; collecting converter station wastewater discharged from a wastewater discharge port through a zero-discharge concentration tank; scale-forming ions in the converter station wastewater are separated out and condensed through a microcrystal device; the converter station wastewater is sprayed to the surface of the cooling coil through a spraying pump and a spraying pipe; and the zero-discharge concentration tank is used for collecting discharged water of the evaporative cooling tower. According to the embodiment of the invention, waste heat generated when the converter valve works can be recovered and used for evaporating spraying wastewater by the evaporation cooling tower, so that the water inlet temperature of the converter valve external cooling system is reduced, and the heat exchange burden and the water consumption of the converter valve external cooling system are reduced; and meanwhile, scale-forming ions are condensed by utilizing the microcrystal device, so that the energy consumption of zero-discharge treatment of the wastewater is reduced. The method can be widely applied to the technical field of zero-emission treatment.

Description

Technical Field

[0001] This application relates to the field of zero-emission treatment technology, and in particular to an evaporative zero-emission system and its control method. Background Technology

[0002] Ultra-high voltage direct current (UHVDC) transmission lines, flexible DC transmission converter valves, and transformers generate a large amount of heat during operation, requiring dedicated converter valve cooling systems to dissipate heat. In water-rich areas, closed-loop cooling towers are typically used as the cold source. This cooling process consumes a significant amount of water, including for cooling tower spray water evaporation, equipment filtration and cleaning, and concentrated wastewater discharge. Taking a single flexible DC converter station as an example, the cooling system consumes over 3000 m³ of water daily and discharges over 1000 m³ of wastewater daily, leading to the following problems: 1) Dedicated water supply facilities need to be set up.

[0003] 2) The discharge of high-concentration saline wastewater affects irrigation of surrounding farmland.

[0004] 3) The wastewater contains certain chemical residues, making it difficult to meet environmental protection emission requirements.

[0005] 4) The nearby sewage treatment plant has limited capacity to receive and process wastewater.

[0006] 5) It affects the quality of surrounding surface water.

[0007] New projects use multi-stage water treatment technology to reduce water discharge, such as re-introducing the concentrate from one stage of reverse osmosis into a new reverse osmosis, nanofiltration, or ultrafiltration system for treatment, thereby reducing water consumption and drainage. However, about 20% of the water still needs to be discharged.

[0008] Existing zero-discharge technologies mainly involve: pre-treating the wastewater with membrane concentration (RO / NF / ED, etc.), then having the concentrated water enter MVR (mechanical vapor recompression), recycling the distilled water produced by condensing the high-temperature steam after evaporation, and having the residual concentrated liquid enter a crystallizer to precipitate solid salts, thereby achieving the goal of zero discharge (no water discharge).

[0009] The existing technology has the following drawbacks: 1) Pretreatment and MVR are prone to scaling - The main drainage of the converter valve cooling system comes from RO concentrate, which has a high salt content. In order to reduce the amount of water treated by MVR, the concentrate needs to be concentrated by the membrane, which makes the concentrate entering the MVR system even harder and prone to scaling in the pretreatment and MVR.

[0010] 2) Unstable operating conditions: The system needs to be processed according to the actual amount of drainage. When there is little or no drainage, the pretreatment and MVR need to be shut down, which can easily lead to scale buildup inside the pretreatment and MVR. Cleaning is required before restarting.

[0011] 3) Requires professional operation and maintenance capabilities: The pretreatment and MVR processes are complex and differ significantly from existing converter station equipment, resulting in a large workload for operation and maintenance, requiring professional operation and maintenance personnel.

[0012] 4) High energy consumption: Each ton of water treatment requires 60kWh to 100kWh of electrical power, which is a large amount of electricity, and the capacity of existing power distribution transformers needs to be increased.

[0013] 5) High investment costs.

[0014] 6) The water temperature during condensate recovery is relatively high, and it needs to be cooled again before it can be used as production water.

[0015] In summary, the technical problems existing in the relevant technologies need to be improved. Summary of the Invention

[0016] The main objective of this application is to propose an evaporative zero-discharge system and its control method. The system recovers the waste heat generated during the operation of the converter valve through a heat exchanger and uses it to evaporate the sprayed wastewater in an evaporative cooling tower. This reduces the inlet water temperature of the converter valve's external cooling system, thereby reducing the heat exchange burden and water consumption of the external cooling system. At the same time, the system utilizes a microcrystal device to coagulate scale-forming ions, reducing the energy consumption of the zero-discharge wastewater treatment and improving the overall energy utilization rate.

[0017] To achieve the above objectives, one aspect of this application proposes an evaporative zero-emission system, including a circulating pump, a heat exchanger, an evaporative cooling tower, a zero-emission concentration tank, a spray pump, spray pipes, and a microcrystalline device. The evaporative cooling tower includes a cooling coil. The outlet of the circulating pump is connected to the secondary side supply port of the heat exchanger via a pipe. The secondary side return port of the heat exchanger is connected to the inlet of the cooling coil via a pipe. The outlet of the cooling coil is connected to the inlet of the circulating pump via a pipe. The primary side supply port of the heat exchanger is connected to the outlet of a converter valve via a pipe. The primary side return port of the heat exchanger is connected to the inlet of the external cooling system of the converter valve via a pipe. The wastewater discharge port of the external cooling system of the converter valve is connected to the zero-emission concentration tank via a pipe. The microcrystalline device is disposed within the zero-emission concentration tank. The spray pump's suction... The water outlet is connected to the zero-discharge concentration tank, the outlet of the spray pump is connected to the spray pipe, the spray pipe is located at the upper part of the evaporative cooling tower, the lower part of the evaporative cooling tower is connected to the zero-discharge concentration tank, the circulating pump is used to drive the cooling medium to circulate between the heat exchanger and the cooling coil, the heat exchanger is used to perform heat exchange between the cooling medium and the drain water discharged from the outlet of the converter valve, the zero-discharge concentration tank is used to collect the converter station wastewater discharged from the wastewater discharge outlet, the microcrystal device is used to precipitate and condense the scale-forming ions in the converter station wastewater, the spray pump is used to draw the converter station wastewater to the spray pipe, the spray pipe is used to spray the converter station wastewater onto the surface of the cooling coil, and the zero-discharge concentration tank is also used to collect the converter station wastewater discharged from the evaporative cooling tower.

[0018] In some embodiments, the system further includes a water supply tank and a water supply pump, wherein the outlet of the water supply tank is connected to the inlet of the water supply pump, and the outlet of the water supply pump is connected to the inlet of the circulation pump via a pipe.

[0019] In some embodiments, the system further includes an expansion buffer device connected to the inlet of the circulating pump via a pipe.

[0020] In some embodiments, the system further includes a bypass valve, through which the primary side supply port of the heat exchanger is connected to the primary side return port of the heat exchanger.

[0021] In some embodiments, the system further includes a temperature sensor group, wherein the primary side liquid supply port, the secondary side liquid supply port, and the secondary side liquid return port of the heat exchanger are all connected to the temperature sensor group.

[0022] In some embodiments, the system further includes a pressure sensor group, wherein the primary side liquid supply port, the primary side liquid return port, the secondary side liquid supply port, and the secondary side liquid return port of the heat exchanger are all connected to the pressure sensor group.

[0023] In some embodiments, the system further includes a flow sensor group and a liquid level sensor, wherein the secondary side return port of the heat exchanger and the wastewater discharge port of the external cooling system of the converter valve are both connected to the flow sensor group, and the zero-discharge thickening tank is connected to the liquid level sensor.

[0024] In some embodiments, the evaporative cooling tower further includes a fan for accelerating the evaporation of the converter station wastewater on the surface of the cooling coil.

[0025] In some embodiments, the evaporation coils of the evaporative cooling tower are made of plastic.

[0026] To achieve the above objectives, another aspect of this application proposes a control method for an evaporation zero-emission system, applied to the aforementioned evaporation zero-emission system, comprising: The cooling medium is driven by a circulating pump to circulate between the heat exchanger and the cooling coil. The cooling medium and the drain water discharged from the outlet of the converter valve are exchanged through a heat exchanger. Wastewater from the converter station discharged from the wastewater discharge outlet is collected through a zero-discharge thickening tank; The scale-forming ions in the converter station wastewater are precipitated and condensed using a microcrystalline device; Wastewater from the converter station is drawn into the spray pipe by a spray pump. The wastewater from the converter station is sprayed onto the surface of the cooling coil through a spray pipe. The wastewater discharged from the evaporative cooling tower at the converter station is collected through a zero-discharge concentration tank.

[0027] The embodiments of this application include at least the following beneficial effects: This application provides an evaporative zero-emission system and its control method. This system uses a circulating pump to drive the cooling medium to circulate between the heat exchanger and the cooling coil, continuously introducing the residual heat from the wastewater drained from the converter valve into the evaporative cooling tower to drive the evaporation of the sprayed wastewater. Simultaneously, the cooling energy generated by the wastewater during evaporation reduces the inlet water temperature of the converter valve's external cooling system, thereby reducing the heat exchange burden on the external cooling system and the water consumption required for heat dissipation, achieving effective recovery and utilization of waste heat. The wastewater discharged from the converter station is collected through a zero-emission concentration tank. The microcrystalline device is used to precipitate and coagulate scale-forming ions in the wastewater, and combined with a spray pump to achieve evaporation and concentration of the wastewater. On the one hand, this effectively reduces the risk of scale formation on the coils, and on the other hand, it achieves zero-discharge treatment of wastewater with low energy consumption, avoiding environmental pollution caused by wastewater discharge. The concentrated wastewater is transported to the spray pipe by the spray pump and sprayed onto the surface of the cooling coil. The sprayed wastewater evaporates rapidly under air circulation conditions, which improves the evaporation and concentration efficiency of the wastewater. At the same time, the evaporation absorbs heat to further enhance the cooling effect on the cooling coil, which further improves the energy utilization rate of the system. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of an evaporative zero-emission system provided in an embodiment of this application; Figure 2 This is a flowchart illustrating the steps of a control method for an evaporative zero-emission system provided in an embodiment of this application. Figure label: 1: Circulating pump; 2: Heat exchanger; 3: Bypass valve; 4: External cooling system for converter valve; 5: Evaporative cooling tower; 6: Expansion buffer device; 7: Makeup water tank; 8: Makeup water pump; 9: Spray pump; 10: Zero-discharge concentration tank; 11: Microcrystalline device; TT: Temperature sensor; LT: Liquid level sensor; FT: Flow sensor; PT: Pressure sensor. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this application; they are merely examples of apparatuses and methods consistent with some aspects of the embodiments of this application as detailed in the appended claims.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0031] The concept of the present invention will now be explained in conjunction with the background art.

[0032] To address the shortcomings of existing technologies, this application provides an evaporative zero-emission system and its control method to achieve the following objectives: Waste heat utilization: The converter valves in the converter station generate a lot of heat, with a single valve chamber generating more than 5000kW of heat. This heat needs to be dissipated by a dedicated cooling system. This technology, through cooperation with the cooling system, transfers heat to the evaporative cooling coils through water, realizing the evaporation of wastewater, while improving the cooling capacity of the original cooling system.

[0033] Spray evaporation: The wastewater discharged from the converter station is used as the spray water for the evaporative cooling tower. The heat generated by the heat exchange valve is used for evaporation, which increases the concentration ratio of the spray water. The cooling tower uses non-metallic heat exchange tubes, so that the coils are less prone to scaling in the high hardness and high salinity spray water.

[0034] Concentrated solution crystallization: As the spray water evaporates, its concentration increases. A specially designed microcrystalline carrier continuously and stably releases microcrystalline elements, enriching the circulating water and causing scale-forming ions to condense into submicrocrystalline particles. This attracts fine suspended matter in the circulating water, forming compact crystalline particles that lose their adhesion, preventing coil clogging. The highly concentrated mixture settles to the bottom of the tank and is then pumped out for filtration or directly sent to a third party for solid waste treatment, meeting the converter station's requirement of no external discharge throughout the year.

[0035] Collaborative control: Based on the operating conditions of the converter valve, the valve cooling system, the water level in the pool, and water quality parameters, the pumps, fans, valves, and sensors in the zero-discharge system are monitored and controlled. Based on the water quality concentration, the sewage pump is activated to filter or discharge scale in the pool.

[0036] Figure 1 This is a schematic diagram of the overall structure of an evaporative zero-emission system provided in an embodiment of the present invention, with reference to... Figure 1This invention provides a zero-emission evaporation system, including a circulating pump, a heat exchanger, an evaporative cooling tower, a zero-emission concentration tank, a spray pump, spray pipes, and a microcrystalline device. The evaporative cooling tower includes a cooling coil. The outlet of the circulating pump is connected to the secondary side supply port of the heat exchanger via a pipe. The secondary side return port of the heat exchanger is connected to the inlet of the cooling coil via a pipe. The outlet of the cooling coil is connected to the inlet of the circulating pump via a pipe. The primary side supply port of the heat exchanger is connected to the outlet of a converter valve via a pipe. The primary side return port of the heat exchanger is connected to the inlet of the converter valve's external cooling system via a pipe. The wastewater discharge port of the converter valve's external cooling system is connected to the zero-emission concentration tank via a pipe. The microcrystalline device is disposed within the zero-emission concentration tank. The suction port of the spray pump is connected to the zero-emission concentration tank. The system is connected to a discharge concentration tank, with the outlet of the spray pump connected to the spray pipe. The spray pipe is located at the top of the evaporative cooling tower, and the bottom of the evaporative cooling tower is connected to the zero-discharge concentration tank. The circulating pump drives the cooling medium to circulate between the heat exchanger and the cooling coil. The heat exchanger performs heat exchange between the cooling medium and the drain water discharged from the outlet of the converter valve. The zero-discharge concentration tank collects the converter station wastewater discharged from the wastewater discharge port. The microcrystal device precipitates and condenses scale-forming ions in the converter station wastewater. The spray pump draws the converter station wastewater to the spray pipe, which sprays the converter station wastewater onto the surface of the cooling coil. The zero-discharge concentration tank also collects the converter station wastewater discharged from the evaporative cooling tower.

[0037] In some embodiments, the system further includes a water supply tank and a water supply pump, wherein the outlet of the water supply tank is connected to the inlet of the water supply pump, and the outlet of the water supply pump is connected to the inlet of the circulation pump via a pipe.

[0038] Specifically, in this embodiment, cooling medium is replenished to the circulating pump through a water replenishment tank and a water replenishment pump, so as to replenish water in a timely manner when water loss occurs during the evaporation process, ensure the water balance of the system, and achieve stable circulation.

[0039] In some embodiments, the system further includes an expansion buffer device connected to the inlet of the circulating pump via a pipe.

[0040] Specifically, in this embodiment, the pressure in the system pipeline is balanced by a buffer expansion device, thereby improving the stability of system operation.

[0041] In some embodiments, the system further includes a bypass valve, through which the primary side supply port of the heat exchanger is connected to the primary side return port of the heat exchanger.

[0042] Specifically, in this embodiment, by setting a bypass valve, the primary side liquid supply port and return port of the heat exchanger are controllably connected. The amount of water drained from the flow exchange valve entering the heat exchanger can be adjusted according to the operating conditions, thereby controlling the heat exchange volume and enhancing the flexibility and adjustability of the system operation.

[0043] In some embodiments, the system further includes a temperature sensor group, wherein the primary side liquid supply port, the secondary side liquid supply port, and the secondary side liquid return port of the heat exchanger are all connected to the temperature sensor group.

[0044] Specifically, in this embodiment, the temperature parameters of the primary and secondary pipelines of the heat exchanger are collected in real time by a group of temperature sensors to provide temperature data support for the automated control of the system.

[0045] In some embodiments, the system further includes a pressure sensor group, wherein the primary side liquid supply port, the primary side liquid return port, the secondary side liquid supply port, and the secondary side liquid return port of the heat exchanger are all connected to the pressure sensor group.

[0046] Specifically, in this embodiment, the pressure of the primary and secondary pipelines of the heat exchanger is monitored by a pressure sensor group, which can detect abnormal risks such as blockage and leakage in a timely manner, improve the safety of the system, and provide pressure data support for the automated control of the system.

[0047] In some embodiments, the system further includes a flow sensor group and a liquid level sensor, wherein the secondary side return port of the heat exchanger and the wastewater discharge port of the external cooling system of the converter valve are both connected to the flow sensor group, and the zero-discharge thickening tank is connected to the liquid level sensor.

[0048] Specifically, in this embodiment, the flow rate of the cooling medium and the wastewater of the converter station is monitored by a flow sensor group, and the liquid level of the zero-discharge thickener is monitored by a liquid level sensor, which facilitates the control of the wastewater recycling ratio and overflow warning. By setting an overflow port in the zero-discharge thickener, when the system fails to shut down and cannot carry out evaporation and thickening, the water in the pool will flow out by gravity after exceeding the overflow port.

[0049] In some embodiments, the evaporative cooling tower further includes a fan for accelerating the evaporation of the converter station wastewater on the surface of the cooling coil.

[0050] Specifically, in this embodiment, the airflow velocity inside the evaporative cooling tower is increased by using a fan, thereby increasing the evaporation rate of the sprayed wastewater on the surface of the cooling coil, thus enhancing the evaporative cooling effect and improving the overall heat exchange performance of the system.

[0051] In some embodiments, the evaporation coils of the evaporative cooling tower are made of plastic.

[0052] Specifically, in this embodiment, to prevent high-concentration spray water from evaporating and forming scale on the cooling tower coils, PP or PE non-metallic plastic pipes with high thermal conductivity (greater than 0.8 W / m·K) are selected as the evaporation coils. Plastic pipes have low surface energy and are not prone to scaling. The low thermal conductivity of plastic pipes also makes them less sensitive to fouling. Since the thermal conductivity of plastic pipes is lower than that of commonly used carbon steel, stainless steel, copper, and other metallic materials, the heat exchange area can be increased by reducing the diameter of the heat exchange tubes to achieve the same heat exchange performance, thereby improving the heat exchange capacity of the evaporative cooling tower per unit size.

[0053] The technical solution of this embodiment will be further described below: In this embodiment, the wastewater not used by the converter station (i.e., the converter station wastewater discharged from the external cooling system 4 of the converter valve) is collected into the zero-discharge thickening tank 10. After the high-concentration converter station wastewater enters the thickening tank, it is induced by the microcrystalline carrier 11 to precipitate scale ions and coagulate, and the solid waste is deposited at the bottom of the tank. The heat generated when the converter valve is working is carried out by the converter valve drainage and flows through the heat exchanger 2 to transfer the heat to the cooling medium on the zero-emission system side (in this embodiment, water can be selected as the cooling medium). After being heated by the heat exchanger 2, the cooling medium of the zero-emission system is sent to the cooling coil of the evaporative cooling tower 5. The spray pump 9 pumps the converter station wastewater in the zero-emission concentration tank 10 to spray onto the surface of the cooling coil of the evaporative cooling tower 5. The evaporative cooling tower fan runs to exchange heat between the air and the converter station wastewater. The heat is carried away by the evaporation of the converter station wastewater. The high-concentration converter station wastewater after evaporation and concentration flows back to the zero-emission concentration tank 10 from the bottom of the evaporative cooling tower 5. The cooled cooling medium re-enters the heat exchanger 2 to reduce the inlet water temperature of the converter valve external cooling system 4, and at the same time absorbs the heat from the converter valve drainage and circulates again.

[0054] In this embodiment, heat exchanger 2 is designed in the direction of the water inlet of the external cooling system 4 of the converter valve, which facilitates heat exchange using a high-temperature heat source and utilizes the evaporation of the discharged water on the cooling tower coil. Evaporative cooling tower 5 is designed in the direction of the water pump inlet to reduce the operating pressure of the cooling tower coil. Evaporative cooling tower 5 can be configured as 1 in operation and 1 standby or 2 in operation and 1 standby, and is designed based on the highest historical wet-bulb temperature.

[0055] During this process, the microcrystalline carrier 11 in the zero-discharge concentration tank 10 induces the precipitation and coagulation of scale-forming ions, and solid waste is deposited at the bottom of the tank. Meanwhile, the spray pump continuously draws wastewater from the tank to the evaporation cooling tower 5 for evaporation and concentration. Under the inducing deposition effect of the microcrystalline carrier 11 and the evaporation and concentration effect of the spray pump 9, the solution concentration in the zero-discharge concentration tank 10 becomes higher and higher. Due to the influence of density, the highly concentrated liquid or solid sinks to the bottom of the tank. A certain capacity space is reserved at the bottom of the concentration tank for storing highly concentrated liquid or solid. Cleaning is carried out during the annual inspection period to achieve zero wastewater discharge.

[0056] When the ambient temperature at the operating location is below zero degrees Celsius, in order to prevent the system from shutting down below zero degrees Celsius, a certain proportion of ethylene glycol can be added to the cooling medium of the zero-emission system according to the local freezing point to prevent the medium from freezing.

[0057] It can be understood that in this embodiment, the heat of the converter valve is carried out by the drain of the converter valve. After the high temperature water flows through the heat exchanger, it transfers the heat to the cooling medium. Then, the heat of the converter valve is transferred to the evaporative cooling tower coil by the pump power, thus realizing the recovery and utilization of the waste heat of the converter valve.

[0058] Meanwhile, the collected wastewater from the converter station is evenly sprayed onto the surface of the evaporative cooling tower coils via a spray pump. Air flows through the coils via a fan, evaporating the sprayed water. The cooling medium inside the cooling coils is cooled by the cooling energy generated by the evaporation of the sprayed water. The cooled medium is then pumped to the heat exchanger on the external cooling system side of the converter valve, reducing the inlet water temperature of the external cooling system, increasing the heat exchange capacity of the entire system, improving reliability and heat exchange redundancy. At the same time, as the heat exchange burden of the original external cooling system of the converter valve is reduced, the evaporation rate of its cooling tower is also reduced, resulting in a significant reduction in the water consumption of the external cooling system of the converter valve, thereby reducing the overall water consumption of the station and realizing the recovery and utilization of the cooling energy during zero-discharge spray evaporation.

[0059] Furthermore, in this embodiment, by combining bypass valves, sensors, and other devices, coordinated control can be achieved based on the operating load of the converter valve, the water temperature of the valve cooling system, the liquid level of the zero-discharge thickener, and the outdoor wet-bulb temperature. When the converter valve load is high, the evaporation and drainage volumes are large, the heat exchange is large, and the heat transferred to the evaporative zero-discharge cooling tower is large, resulting in strong evaporation capacity and high efficiency. Conversely, when the converter valve load is low or it is shut down, the evaporation and drainage volumes are small, the heat exchange is small, and the heat transferred to the evaporative zero-discharge cooling tower is small, resulting in less evaporation or no evaporation to meet the requirements. For example, when the liquid level of the zero-discharge thickener meets the start-up conditions (above the start-up liquid level), the converter valve operates under load and the outlet water temperature (greater than or equal to 28°C) meets the zero-discharge start-up conditions. The zero-discharge system (1-circulation pump) starts, and the temperature entering the external cooling system of the converter valve is controlled by frequency conversion to be greater than or equal to 25°C and simultaneously higher than the dew point temperature. The spray pump operates, and the evaporative cooling tower fan operates by frequency conversion to adjust the air volume. When the circulating pump, spray pump, and evaporative cooling tower fan are all running, the water temperature entering the external cooling system of the converter valve will decrease, reducing the heat exchange capacity of the external cooling system. Consequently, the evaporation and drainage volume of the external cooling system decrease, reducing the amount of water entering the zero-discharge thickener and creating a virtuous cycle. This also improves the reliability of the converter valve cooling system (by increasing the heat exchange capacity). The zero-discharge thickener is equipped with an overflow port. When the system fails and evaporation and thickening cannot proceed, the water in the tank overflows and is discharged by gravity. The outlet water temperature of the converter valve for waste heat absorption in the zero-discharge system is designed to be 5°C below the rated design temperature, and the temperature difference between the two sides of the heat exchanger is designed to be 5°C.

[0060] In this embodiment, energy consumption only includes pumps, fans, and control systems. The electricity consumption per ton of water treated through zero-emission evaporation, achieved via waste heat recovery and cold energy recovery, can be reduced to below 8 kWh, only 5%-10% of the electricity consumption of traditional mechanical evaporation. During operation, the zero-emission evaporative cooling tower provides at least 20% of the rated heat dissipation of the converter valve cooling system (the specific amount is determined based on the external cold energy discharge from the converter valve), equivalent to saving 20% ​​of the original water consumption of the converter valve cooling system.

[0061] For example, improvements in energy efficiency can be verified through the following calculation process: When the heat dissipation power of the converter valve is constant, the calculation method for the evaporation water volume of the external cooling system of the converter valve is as follows: Q1 = P / §; Where Q1 is the water loss due to evaporation (L / s), P is the total heat dissipation of the converter valve (kW), and § is the latent heat of vaporization of water (2260kJ / kg℃).

[0062] The blowdown volume of the heat exchange valve external cooling system is calculated using the following formula: Q2 = Q1 / (N-1) Where Q2 is the wastewater loss (L / s), Q1 is the evaporation loss (L / s), and N is the concentration factor (adopting advanced reverse osmosis treatment technology, the concentration factor can be 8-10).

[0063] The reverse osmosis permeate recovery rate is generally designed to be 70%. After the 30% of the wastewater is completely evaporated in the zero-discharge cooling tower, it will provide about 30% of the cooling capacity for the external cooling system of the converter valve. The evaporation loss of the external cooling system of the converter valve will be reduced by 30% (the evaporation capacity is proportional to the total heat dissipation of the converter valve). The increased cooling capacity of 30% improves the reliability of the external cooling system of the converter valve.

[0064] The drainage volume of the converter valve cooling system is designed as the evaporation water volume of a zero-discharge system, and the required waste heat recovery is: According to: Q = Cm△t, △t is the temperature difference between the inlet and outlet water, in K (°C), and △t is designed for 10°C; m is the design flow rate, in l / s; Q is the heat, in kW; C is the specific heat capacity of the medium, in kJ / (kg·k), and the specific heat capacity of water at 25°C is taken as 4.18.

[0065] Q represents the waste heat that the converter valve needs to provide. Since the drainage volume is only 30% of the rated operating capacity of the converter valve, the waste heat that the converter valve needs to provide for evaporation is also only 30% of the rated operating capacity.

[0066] Zero-discharge thickener capacity calculation: According to the requirements of industrial tap water standards, the total dissolved solids (TDS) in tap water is calculated at 1000 mg / L (hardness 450 mg / L). Therefore, the total dissolved solids per ton of tap water is 1 kg. The total dissolved solids in the total annual wastewater discharge is calculated as the minimum volume of the zero-discharge thickener. The remaining usable volume of the zero-discharge thickener is sufficient to meet the total wastewater discharge for 3 days after a system failure.

[0067] The total capacity of the thickening tank is: C 总 =C 固 + C 3天排水量 It can be understood that this embodiment utilizes the relationship between the heat generated by the converter valve and the cooling water consumption and drainage volume to recover the waste heat from the converter valve's operation and to heat, evaporate, and concentrate the discharged wastewater, achieving zero discharge of wastewater from the converter station. Through coordinated operation and control, the utilization of waste heat from the converter valve's operation and the utilization of the cooling energy generated by the zero-discharge spray evaporation are achieved in one system, thus solving the goal of zero discharge of wastewater from the converter station. At the same time, the cooling energy generated by the spray evaporation during the zero-discharge process enhances the heat dissipation capacity of the external cooling system of the converter valve, reduces the temperature entering the external cooling system of the converter valve, and improves the reliability of the converter valve cooling system. The use of an intermediate circulation for heat and cooling energy transfer ensures that the zero-discharge system does not... It will affect the operation of the converter valve cooling system; the evaporation process utilizes the waste heat generated by the converter valve, resulting in low system energy consumption, only 5%-10% of the power consumption of traditional mechanical evaporation; non-metallic plastic evaporation coils are used, which have low thermal conductivity, are not sensitive to dirt, and have low surface energy, making them less prone to scaling; combined with microcrystalline carrier-induced descaling technology, scale-forming ions are induced to precipitate and condense through microcrystalline carriers, and solid waste is recovered through a filtration device, achieving the goal of zero wastewater discharge; when the ambient temperature of the place of use is below zero degrees, in order to prevent the system from shutting down below zero degrees, a certain proportion of ethylene glycol can be added to the cooling medium of the zero-discharge system according to the local freezing point to prevent the medium from freezing.

[0068] Please see Figure 2 This application also provides a control method for a zero-emission evaporation system, applied to the aforementioned zero-emission evaporation system, comprising: The cooling medium is driven by a circulating pump to circulate between the heat exchanger and the cooling coil. The cooling medium and the drain water discharged from the outlet of the converter valve are exchanged through a heat exchanger. Wastewater from the converter station discharged from the wastewater discharge outlet is collected through a zero-discharge thickening tank; The scale-forming ions in the converter station wastewater are precipitated and condensed using a microcrystalline device; Wastewater from the converter station is drawn into the spray pipe by a spray pump. The wastewater from the converter station is sprayed onto the surface of the cooling coil through a spray pipe. The wastewater discharged from the evaporative cooling tower at the converter station is collected through a zero-discharge concentration tank.

[0069] It is understood that the content of the above method embodiments is applicable to the present device embodiments. The specific functions implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0070] This application also provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the above-described method. This electronic device can be any smart terminal, including tablet computers, in-vehicle computers, etc.

[0071] It is understood that the content of the above system embodiments is applicable to this method embodiment. The specific functions implemented in this method embodiment are the same as those in the above system embodiments, and the beneficial effects achieved are also the same as those achieved in the above system embodiments.

[0072] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0073] Those skilled in the art will understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of this application, and may include more or fewer steps than shown, or combine certain steps, or different steps.

[0074] The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0075] Those skilled in the art will understand that all or some of the steps in the methods disclosed above, as well as the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or suitable combinations thereof.

[0076] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0077] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0078] In the embodiments provided in this application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between systems or units may be electrical, mechanical, or other forms.

[0079] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0080] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. A zero-emission evaporation system, characterized in that, The system includes a circulating pump, a heat exchanger, an evaporative cooling tower, a zero-discharge thickening tank, a spray pump, spray pipes, and a microcrystalline device. The evaporative cooling tower includes a cooling coil. The outlet of the circulating pump is connected to the secondary side supply port of the heat exchanger via a pipe. The secondary side return port of the heat exchanger is connected to the inlet of the cooling coil via a pipe. The outlet of the cooling coil is connected to the inlet of the circulating pump via a pipe. The primary side supply port of the heat exchanger is connected to the outlet of a converter valve via a pipe. The primary side return port of the heat exchanger is connected to the inlet of the external cooling system of the converter valve via a pipe. The wastewater discharge port of the external cooling system of the converter valve is connected to the zero-discharge thickening tank via a pipe. The microcrystalline device is located within the zero-discharge thickening tank. The suction port of the spray pump is connected to the zero-discharge thickening tank. The outlet of the spray pump is connected to the spray pipe, which is located at the top of the evaporative cooling tower. The bottom of the evaporative cooling tower is connected to the zero-discharge concentration tank. The circulating pump drives the cooling medium to circulate between the heat exchanger and the cooling coil. The heat exchanger performs heat exchange between the cooling medium and the drain water discharged from the outlet of the converter valve. The zero-discharge concentration tank collects the wastewater discharged from the converter station. The microcrystal device precipitates and condenses scale-forming ions in the wastewater of the converter station. The spray pump draws the wastewater from the converter station to the spray pipe, which sprays the wastewater onto the surface of the cooling coil. The zero-discharge concentration tank also collects the wastewater discharged from the evaporative cooling tower.

2. The zero-emission evaporation system according to claim 1, characterized in that, The system also includes a water supply tank and a water supply pump. The outlet of the water supply tank is connected to the inlet of the water supply pump, and the outlet of the water supply pump is connected to the inlet of the circulation pump through a pipe.

3. The zero-emission evaporation system according to claim 1, characterized in that, The system also includes an expansion buffer device, which is connected to the inlet of the circulating pump via a pipe.

4. The zero-emission evaporation system according to claim 1, characterized in that, The system also includes a bypass valve, and the primary side supply port of the heat exchanger is connected to the primary side return port of the heat exchanger through the bypass valve.

5. The zero-emission evaporation system according to claim 1, characterized in that, The system also includes a temperature sensor group, and the primary side liquid supply port, the secondary side liquid supply port, and the secondary side liquid return port of the heat exchanger are all connected to the temperature sensor group.

6. The zero-emission evaporation system according to claim 1, characterized in that, The system also includes a pressure sensor group, and the primary side liquid supply port, the primary side liquid return port, the secondary side liquid supply port, and the secondary side liquid return port of the heat exchanger are all connected to the pressure sensor group.

7. The zero-emission evaporation system according to claim 1, characterized in that, The system also includes a flow sensor group and a liquid level sensor. The secondary side return port of the heat exchanger and the wastewater discharge port of the external cooling system of the converter valve are both connected to the flow sensor group, and the zero-discharge thickening tank is connected to the liquid level sensor.

8. The zero-emission evaporation system according to claim 1, characterized in that, The evaporative cooling tower also includes a fan, which is used to accelerate the evaporation of the converter station wastewater on the surface of the cooling coil.

9. The zero-emission evaporation system according to claim 1, characterized in that, The evaporation coils of the evaporative cooling tower are made of plastic.

10. A control method for a zero-emission evaporation system, applied to a zero-emission evaporation system according to any one of claims 1-9, characterized in that, include: The cooling medium is driven by a circulating pump to circulate between the heat exchanger and the cooling coil. The cooling medium and the drain water discharged from the outlet of the converter valve are exchanged through a heat exchanger. Wastewater from the converter station discharged from the wastewater discharge outlet is collected through a zero-discharge thickening tank; The scale-forming ions in the converter station wastewater are precipitated and condensed using a microcrystalline device; Wastewater from the converter station is drawn into the spray pipe by a spray pump. The wastewater from the converter station is sprayed onto the surface of the cooling coil through a spray pipe. Wastewater from the converter station discharged from the evaporative cooling tower is collected through a zero-discharge concentration tank.

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