Full-load wastewater zero-discharge evaporation system and method

Abstract

The invention belongs to the technical field of wastewater treatment, and provides a full-load wastewater zero-discharge evaporation system and method.The system comprises an evaporation tower, a flue gas circulation subsystem, a wastewater atomization subsystem, an ash conveying treatment subsystem and an interlocking control subsystem, and the flue gas circulation subsystem, the wastewater atomization subsystem, the ash conveying treatment subsystem and the interlocking control subsystem are connected with the evaporation tower; the flue gas circulation subsystem is used for introducing flue gas into the evaporation tower through the flue gas circulation channel; the wastewater atomization subsystem is used for atomizing to-be-treated wastewater and then inputting the wastewater into the evaporation tower, so that the atomized to-be-treated wastewater is in contact with flue gas; the ash conveying treatment subsystem is used for collecting solid ash separated out in the evaporation process and discharging the ash through compressed air. The interlocking control subsystem is used for obtaining unit load data in the evaporation process and conducting interlocking control on at least part of key components in the flue gas circulation subsystem, the waste water atomization subsystem and the ash conveying treatment subsystem according to the unit load data. According to the scheme, the long-period scaling-free operation of the evaporation system can be realized, and the reliability and the safety of an evaporation link are improved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a full-load wastewater zero-discharge evaporation system and method. Background Technology

[0002] The production process of thermal power plants generates a large amount of wastewater, among which the desulfurization wastewater produced by the limestone-gypsum wet flue gas desulfurization process is the most problematic. This type of wastewater not only contains high concentrations of sulfates, heavy metals, and suspended solids, but is also rich in various dissolved salts and organic matter, making it complex in quality and highly corrosive. If discharged directly without effective treatment, it will cause serious pollution to the surrounding soil, water bodies, and other ecological environments, threatening ecological balance and human health.

[0003] Among related technologies, thermal zero-discharge technology has become one of the core means of environmental protection transformation of thermal power plants because it can effectively separate water and salt in wastewater through physical evaporation and concentration, ultimately achieving water recycling and solid salt resource utilization. However, in practical applications, existing thermal zero-discharge technologies are prone to scale buildup due to the dynamic changes in the operating load of thermal power plant units. This scale buildup can clog flue gas ducts or evaporation towers, affecting the evaporation treatment effect and even posing safety hazards.

[0004] It is evident that traditional zero-discharge evaporation solutions for wastewater suffer from technical problems such as poor load adaptability, easy scale buildup, and insufficient reliability and safety. Summary of the Invention

[0005] This invention provides a full-load wastewater zero-discharge evaporation system and method to solve the defects of traditional wastewater zero-discharge evaporation schemes, such as poor load adaptability, easy scale buildup, and insufficient reliability and safety.

[0006] On the one hand, the present invention provides a full-load wastewater zero-discharge evaporation system, including: an evaporation tower and a flue gas circulation subsystem, a wastewater atomization subsystem, an ash conveying and treatment subsystem and an interlocking control subsystem connected to the evaporation tower;

[0007] The interlocking control subsystem is connected to the flue gas recirculation subsystem, the wastewater atomization subsystem, and the ash conveying and treatment subsystem, respectively.

[0008] The flue gas recirculation subsystem is used to introduce flue gas into the evaporation tower through the flue gas circulation channel; the wastewater atomization subsystem is used to atomize the wastewater to be treated and input it into the evaporation tower so that the atomized wastewater to be treated comes into contact with the flue gas; the ash conveying subsystem is used to collect the solid ash residue precipitated during the evaporation process and discharge the ash residue using compressed air; the interlocking control subsystem is used to acquire the unit load data during the evaporation process and, based on the unit load data, to perform interlocking control on at least some key components of the flue gas recirculation subsystem, the wastewater atomization subsystem, and the ash conveying subsystem.

[0009] According to the full-load wastewater zero-discharge evaporation system provided by the present invention, the flue gas circulation subsystem includes: an air preheater inlet pipeline, a booster fan, and an air preheater outlet pipeline;

[0010] The air preheater inlet pipe is connected to the booster fan, the booster fan is connected to the flue gas inlet at the top of the evaporator, and the air preheater outlet pipe is connected to the flue gas outlet at the bottom of the evaporator.

[0011] According to the full-load wastewater zero-discharge evaporation system provided by the present invention, the wastewater atomization subsystem includes: a closed water input pipeline, a lubricating oil pump, a cooler, and an atomization device;

[0012] The closed-loop water input pipeline is connected to the lubricating oil pump and the cooler respectively. The lubricating oil pump and the cooler are both connected to the atomizing device, which is connected to the atomizing port at the top of the evaporation tower.

[0013] According to the full-load wastewater zero-discharge evaporation system provided by the present invention, the atomizing device includes: a shower-type distributor, an atomizing body, a drive motor, and two-stage series nozzles;

[0014] The shower-type distributor is used to divide the wastewater to be treated into fine streams and send them into the atomizing body; the atomizing body, driven by the drive motor, atomizes the fine streams into droplets through the two-stage series nozzles and sends them into the evaporation tower.

[0015] According to the full-load wastewater zero-discharge evaporation system provided by the present invention, the ash conveying subsystem includes: ash discharge pipeline, ash storage tank, air supply pipeline, ash conveying pipeline, and slag bin;

[0016] One end of the ash discharge pipe is connected to the bottom of the evaporation tower, the other end of the ash discharge pipe, the gas supply pipe, and one end of the ash supply pipe are all connected to the ash storage tank, and the other end of the gas supply pipe is connected to the slag bin.

[0017] The ash discharge pipe is used to send the solid ash residue precipitated after the evaporation of the wastewater to be treated in the evaporation tower to the ash storage tank. The air supply pipe is used to send compressed air into the ash storage tank so that the solid ash residue can be transported by pneumatic force through the ash discharge pipe to the slag bin for storage.

[0018] According to the full-load wastewater zero-discharge evaporation system provided by the present invention, at least three short-connectors are provided on the ash delivery pipeline, and the bottom of the ash storage tank is provided with multiple cleaning holes for cleaning ash slag clumps inside the tank.

[0019] According to the full-load wastewater zero-discharge evaporation system provided by the present invention, an inlet flue gas baffle is provided at the connection between the evaporation tower and the inlet of the flue gas circulation channel;

[0020] The interlocking control subsystem includes a controller, which is used for:

[0021] If the unit load data is higher than the set upper limit of the load, the opening of the inlet flue gas damper is reduced, and the opening of the inlet flue gas damper is above the set lower limit of the opening.

[0022] According to the full-load wastewater zero-discharge evaporation system provided by the present invention, the interlocking control subsystem further includes: multiple temperature sensors, which are respectively installed at multiple key monitoring points of the evaporation tower, and all multiple temperature sensors are connected to the controller;

[0023] The controller is also used for:

[0024] Acquire temperature data and unit load data from various key monitoring points collected by the multiple temperature sensors, and determine the key flue gas temperature value inside the evaporator based on the temperature data;

[0025] If the critical flue gas temperature value is higher than the set upper temperature limit, the closed water input pipeline in the wastewater atomization subsystem is controlled to be opened.

[0026] If the critical flue gas temperature value is lower than the set lower limit, the closed water input pipeline in the wastewater atomization subsystem is shut off.

[0027] According to the full-load wastewater zero-discharge evaporation system provided by the present invention, the interlocking control subsystem further includes: a pressure sensor, wherein the pressure sensor is located at two air preheaters near the air preheater inlet pipe, and the pressure sensor is connected to the controller;

[0028] The controller is also used for:

[0029] Acquire the pressure data collected by the pressure sensor, and determine the air preheater differential pressure value based on the pressure data;

[0030] If the air preheater differential pressure value is lower than the set differential pressure lower limit, and / or the unit load data is lower than the set load lower limit, then all subsystems will be controlled to stop operating.

[0031] On the other hand, the present invention also provides a full-load wastewater zero-discharge evaporation method, based on any of the above-described full-load wastewater zero-discharge evaporation systems, the method comprising:

[0032] Flue gas is introduced into the evaporator through the flue gas circulation channel via the flue gas recirculation subsystem;

[0033] The wastewater to be treated is atomized by the wastewater atomization subsystem and then fed into the evaporation tower so that the atomized wastewater to be treated comes into contact with the flue gas.

[0034] The solid ash residue precipitated during the evaporation process is collected by the ash handling subsystem and discharged using compressed air;

[0035] The unit load data during the evaporation process is obtained through the interlocking control subsystem, and based on the unit load data, at least some key components of the flue gas circulation subsystem, the wastewater atomization subsystem, and the ash conveying and treatment subsystem are interlocked and controlled.

[0036] The present invention provides a full-load wastewater zero-discharge evaporation system and method, which introduces flue gas into the evaporation tower through a flue gas circulation subsystem using a flue gas flow channel; a wastewater atomization subsystem atomizes the wastewater to be treated and inputs it into the evaporation tower so that the atomized wastewater comes into contact with the flue gas; an ash handling subsystem collects the solid ash residue precipitated during the evaporation process and discharges the ash residue using compressed air; and an interlocking control subsystem acquires unit load data during the evaporation process and, based on the unit load data, interlocks and controls at least some key components in the flue gas circulation subsystem, wastewater atomization subsystem, and ash handling subsystem. This scheme utilizes compressed air to discharge the ash residue and uses the interlocking control subsystem to acquire unit load data during the evaporation process. Based on the unit load data, it interlocks and controls at least some key components in each subsystem, improving the load adaptability of the evaporation process, enabling long-term scale-free operation of the evaporation system, and improving the reliability and safety of the evaporation process. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0038] Figure 1This is a schematic diagram of the structural framework of the full-load wastewater zero-discharge evaporation system provided in an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram showing some structural details of the full-load wastewater zero-discharge evaporation system in an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of the atomizing device in an embodiment of the present invention;

[0041] Figure 4 This is a schematic flowchart of the full-load wastewater zero-discharge evaporation method provided in an embodiment of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0043] The following is combined Figures 1 to 4 This invention describes the detailed scheme of the full-load wastewater zero-discharge evaporation system and method provided in the embodiments of the present invention.

[0044] like Figure 1 As shown, the full-load wastewater zero-discharge evaporation system provided in this embodiment of the invention mainly includes: an evaporation tower 100 and a flue gas circulation subsystem 110, a wastewater atomization subsystem 120, an ash conveying and treatment subsystem 130 and an interlocking control subsystem 140 connected to the evaporation tower 100.

[0045] The interlocking control subsystem 140 is connected to the flue gas recirculation subsystem 110, the wastewater atomization subsystem 120, and the ash conveying and treatment subsystem 130, respectively.

[0046] The flue gas recirculation subsystem 110 is used to introduce flue gas into the evaporation tower 100 through the flue gas circulation channel; the wastewater atomization subsystem 120 is used to atomize the wastewater to be treated and then input it into the evaporation tower 100 so that the atomized wastewater to be treated comes into contact with the flue gas; the ash conveying and treatment subsystem 130 is used to collect the solid ash residue precipitated during the evaporation process and to discharge the ash residue using compressed air; the interlocking control subsystem 140 is used to acquire the unit load data during the evaporation process and, based on the unit load data, to perform interlocking control on at least some key components of the flue gas recirculation subsystem 110, the wastewater atomization subsystem 120, and the ash conveying and treatment subsystem 130.

[0047] In one embodiment, the flue gas recirculation subsystem specifically includes: an air preheater inlet pipe, a booster fan, and an air preheater outlet pipe.

[0048] The air preheater inlet pipe is connected to the booster fan, the booster fan is connected to the flue gas inlet at the top of the evaporator, and the air preheater outlet pipe is connected to the flue gas outlet at the bottom of the evaporator.

[0049] like Figure 2 As shown, the air preheater inlet pipeline specifically includes two flue gas pipelines introduced from flue gas inlet 1 and flue gas inlet 2 respectively. One flue gas pipeline is equipped with air preheater N2 and valves Z11 and Z12; the other flue gas pipeline is equipped with air preheater N3 and valves Z13 and Z14. Both flue gas pipelines lead to booster fans. In this embodiment, there are two booster fans, W1 and W2. One booster fan is operating normally, and the other booster fan is on standby. The pipeline where booster fan W1 is located is equipped with valve Z9, and the pipeline where booster fan W2 is located is equipped with valve Z10.

[0050] like Figure 2 As shown, the air preheater outlet pipeline specifically includes valves Z15, Z16, and Z17. One end of valve Z17 is connected to the flue gas outlet of the evaporator, and the other end is connected to valves Z15 and Z16 respectively. Valve Z15 is connected to the pipeline where air preheater N2 is located, and valve Z16 is connected to the pipeline where air preheater N3 is located, so that the flue gas is output through the two pipelines.

[0051] In this embodiment, the above-mentioned setup can construct a flue gas circulation path for the air preheater inlet pipe, booster fan, evaporator tower, and air preheater outlet pipe, utilizing the original waste heat of the boiler flue gas as a heat source for wastewater evaporation, eliminating the need for additional heating devices and thus achieving the effect of reducing energy consumption.

[0052] In practical applications, the flue gas inlet of the evaporator is equipped with a steam-driven regulating valve, which can adjust the amount of flue gas entering the evaporator according to the unit load data, so as to avoid the problem of excessive flue gas causing the temperature inside the evaporator to be too high, or insufficient flue gas causing insufficient evaporation efficiency.

[0053] In this embodiment, an axial flow booster fan can be used to solve the problem of insufficient flue gas differential pressure under low load conditions. When the unit load is 50% of the rated load, the booster fan can be started to increase the flue gas pressure to 0.5 kPa, ensuring that the flue gas differential pressure entering the evaporation tower is above 0.7 kPa, which meets the airflow velocity and heat required for wastewater atomization and evaporation, and achieves the effect of not shutting down the system under low load.

[0054] In one embodiment, the wastewater atomization subsystem specifically includes: a closed-loop water inlet pipeline, a lubricating oil pump, a cooler, and an atomization device.

[0055] The closed-loop water inlet pipeline is connected to the lubricating oil pump and the cooler respectively. Both the lubricating oil pump and the cooler are connected to the atomizing equipment, which is connected to the atomizing port at the top of the evaporation tower.

[0056] like Figure 2 As shown, the closed water input pipeline includes two branches. One branch is connected to the atomizing device through valves Z1 and Z2, and the other branch is connected to the lubricating oil pump and cooler N1 through valves Z3, Z4, Z5 and Z6. In this embodiment, two lubricating oil pumps, M1 and M2, are provided. The two lubricating oil pumps and the cooler are connected to the atomizing device through parallel pipelines.

[0057] In this embodiment, the two lubricating oil pumps are in a one-in-use and one-in-standby relationship, which can provide lubricating oil with a pressure of 0.1-0.2MPa to the rotating part of the drive motor in the atomizing device, reduce mechanical wear, ensure the long-term stable operation of the atomizing device, and avoid atomization interruption due to motor failure.

[0058] In one embodiment, such as Figure 2 and Figure 3 As shown, the atomizing device specifically includes: a shower-type distributor 210, an atomizing body 220, a drive motor M, and two-stage series nozzles 230.

[0059] The shower-type distributor 210 is used to divide the wastewater to be treated into fine streams and send them into the atomizer 220; the atomizer 220, driven by the drive motor M, atomizes the fine streams into droplets through two-stage series nozzles 230 and sends them into the evaporation tower.

[0060] In this embodiment, the shower-type distributor 210 first divides the wastewater to be treated into fine streams to avoid the wastewater from concentrating and impacting the two-stage series nozzles 230; the two-stage series nozzles 230, in conjunction with the drive motor M, atomize the wastewater to be treated into tiny droplets, increasing the contact area with the flue gas and improving the evaporation efficiency, thereby effectively reducing the probability of scaling on the tower wall caused by poor atomization.

[0061] Understandably, the drive motor can provide high-speed power to the atomizer, and is the core driving component for converting the wastewater to be treated from liquid to mist, ensuring uniform droplet size and adapting to the needs of flue gas evaporation.

[0062] In one embodiment, the ash conveying subsystem specifically includes: an ash discharge pipeline, an ash storage tank, an air supply pipeline, an ash delivery pipeline, and a slag bin.

[0063] One end of the ash discharge pipe is connected to the bottom of the evaporation tower, and the other end of the ash discharge pipe, the gas supply pipe, and one end of the ash supply pipe are all connected to the ash storage tank. The other end of the gas supply pipe is connected to the slag bin.

[0064] The ash discharge pipeline is used to send the solid ash residue precipitated after the evaporation of the wastewater to be treated in the evaporation tower to the ash storage tank. The air supply pipeline is used to send compressed air into the ash storage tank so that the solid ash residue can be transported to the slag bin for storage by pneumatic means through the ash discharge pipeline.

[0065] like Figure 2 As shown, the ash discharge pipe is equipped with valve Z18, and the air supply pipe is equipped with valves Z19 and Z20. The air supply pipe can deliver compressed air at 0.6-0.7 MPa. The solid ash residue precipitated after the wastewater in the evaporation tower evaporates falls into the ash storage tank through the ash discharge pipe. The compressed air at 0.6-0.7 MPa is used as power to pneumatically transport the ash residue in the ash storage tank to the slag bin for storage, thereby realizing the separation of ash residue and wastewater and completing the final step of zero wastewater discharge.

[0066] Preferably, the ash conveying pipe is equipped with at least three shorting connectors, see [reference]. Figure 2 In this embodiment, three shorting components, D1, D2 and D3, are provided, and the bottom of the ash storage tank is provided with multiple cleaning holes for cleaning up ash clumps inside the tank.

[0067] Considering the risk of ash caking due to poor atomization, this embodiment sets at least three short connectors at the bends of the ash delivery pipeline. When caking occurs, the short connectors can be removed for direct cleaning. The cleaning hole at the bottom of the ash storage tank facilitates the cleaning of caking accumulated inside the tank, avoiding the problem of system shutdown caused by pipeline or ash storage tank blockage, thereby improving the operational stability and reliability of the entire system.

[0068] In one embodiment, an inlet flue gas baffle is provided at the connection between the evaporator tower and the inlet of the flue gas flow channel.

[0069] Furthermore, the interlocking control subsystem specifically includes: a controller, which is used for:

[0070] If the unit load data is higher than the set upper limit of the load, the opening of the inlet flue gas damper will be reduced, and the opening of the inlet flue gas damper will be above the set lower limit of the opening.

[0071] In this embodiment, when the unit load data is higher than 80% of the rated load, it can be determined that it is in a high load state. At this time, the boiler flue gas volume is sufficient and the temperature is high, which can easily lead to excessively high temperature in the evaporator. By reducing the opening of the inlet flue gas damper, the amount of flue gas entering the evaporator can be reduced, and the heat of the flue gas can be roughly adjusted. It should be noted that the opening of the inlet flue gas damper should be above the set lower limit value to avoid the problem of blockage caused by the opening being too small. The lower limit value can be set to 60%.

[0072] In one embodiment, the interlocking control subsystem may further include: multiple temperature sensors, each located at multiple key monitoring points on the evaporator tower, and all temperature sensors connected to a controller. Figure 2As shown, the specific locations of multiple key monitoring points can be found in [reference needed]. Figure 2 P1, P2, P3, P4, P5, P6, and P7 in the diagram refer to important locations such as the flue gas inlet, upper part, middle part, lower part, and flue gas outlet of the evaporator.

[0073] Furthermore, the controller can also be used for:

[0074] The system acquires temperature data and unit load data from multiple temperature sensors at various key monitoring points, and determines the key flue gas temperature values ​​within the evaporator based on the temperature data.

[0075] In this embodiment, the temperature data of each key monitoring point can be weighted and averaged to obtain the key flue gas temperature value. The weight value corresponding to each key monitoring point can be reasonably set according to the actual temperature control requirements.

[0076] If the critical flue gas temperature is higher than the set upper temperature limit, the closed water input pipeline in the wastewater atomization subsystem will be opened.

[0077] If the critical flue gas temperature is lower than the set lower limit, the closed water input pipeline in the wastewater atomization subsystem will be shut off.

[0078] In this embodiment, the upper limit of the set temperature can be set to 240°C. When the critical flue gas temperature is above 240°C, the closed water input pipeline in the wastewater atomization subsystem can be opened to turn on the closed water, i.e., to turn on the cooling water, thereby reducing the temperature of the wastewater entering the atomization equipment and preventing the wastewater to be treated from instantly vaporizing and precipitating solids at the nozzle. The lower limit of the set temperature can be set to 160°C. When the critical flue gas temperature is below 160°C, the closed water input pipeline in the wastewater atomization subsystem can be turned off to shut off the cooling water, preventing the temperature from being too low and affecting subsequent evaporation. Ultimately, the tower wall temperature is stabilized at around 180°C, which can ensure evaporation efficiency and prevent solids from forming scale on the wall.

[0079] In one embodiment, the interlocking control subsystem may further include: a pressure sensor located at two air preheaters near the air preheater inlet pipe, and the pressure sensor is connected to the controller.

[0080] The controller can also be used for:

[0081] Acquire pressure data collected by pressure sensors and determine the air preheater differential pressure value based on the pressure data.

[0082] If the air preheater differential pressure value is lower than the set differential pressure lower limit, and / or the unit load data is lower than the set load lower limit, then all subsystems will be shut down.

[0083] In this embodiment, when no booster fan is running and the unit load data is lower than the set lower load limit, such as lower than 50% of the rated load, and / or the air preheater differential pressure is lower than 0.5 kPa, all subsystems can be controlled to stop operation, thereby cutting off the entire full-load wastewater zero-discharge evaporation system and avoiding atomization failure or equipment malfunction due to insufficient flue gas parameters.

[0084] In practical applications, the workflow of the entire full-load wastewater zero-discharge evaporation system is as follows:

[0085] First, high-temperature flue gas is drawn from the inlet of the boiler air preheater through the flue gas circulation path between the air preheater and the evaporator, and then transported to the evaporator via the air preheater inlet pipeline. During this process, the high-temperature flue gas first passes through the flue gas damper, which can initially adjust the flue gas volume according to the real-time load of the unit to ensure that the total amount of flue gas entering the evaporator matches the wastewater treatment requirements.

[0086] Afterwards, the wastewater to be treated (such as desulfurization wastewater) enters the atomization equipment at the top of the evaporation tower through the conveying pipeline. It is first divided into fine streams by the spray-type distributor to avoid the wastewater from concentrating and impacting the nozzles. Then, driven by the drive motor, it is atomized into tiny droplets through two-stage series nozzles. This fine atomization design can maximize the contact area between wastewater and flue gas, laying the foundation for efficient evaporation.

[0087] In this process, the atomized wastewater droplets come into direct contact with the high-temperature flue gas entering the evaporation tower, rapidly absorbing the waste heat of the flue gas. The water evaporates instantly into water vapor, which returns to the air preheater outlet flue along with the flue gas through the air preheater outlet pipeline. Finally, it enters the subsequent environmental protection treatment system (such as desulfurization and denitrification) with the main flue gas from the boiler to meet emission standards. Meanwhile, solid impurities in the wastewater (such as salts and suspended solids) are precipitated out due to water evaporation, forming solid ash slag, thus completing the core step of water-slag separation.

[0088] To address the fluctuations in flue gas parameters caused by load variations in thermal power plant units, a combined strategy of booster fans and flue gas dampers is employed to achieve full-load adaptation. When the unit is under low load, such as when the unit load data is below 50% of the rated load, the boiler flue gas volume decreases and the differential pressure drops. At this time, the booster fans are activated to increase the differential pressure of the flue gas entering the evaporator to above 0.7 kPa, ensuring that the flue gas volume and flow rate meet the requirements for wastewater atomization and evaporation, and avoiding the forced shutdown of traditional systems due to insufficient flue gas. Simultaneously, the opening of the flue gas damper at the inlet is increased to introduce as much usable flue gas as possible, ensuring the supply of heat source.

[0089] When the unit is under high load, such as when the unit load data is higher than 80% of the rated load, the boiler flue gas volume is excessive and the temperature is too high. At this time, there is no need to start the booster fan. Instead, the flue gas volume entering the evaporator is precisely reduced by reducing the opening of the flue gas damper at the inlet of the evaporator (ensuring that the opening of the flue gas damper is not less than 60%). This avoids the problem of shortened heat exchange time and insufficient wastewater evaporation caused by excessive flue gas velocity. It also prevents the high-speed flue gas from scouring the equipment and aggravating wear. This ensures that the flue gas volume is precisely matched with the wastewater treatment volume and maintains stable evaporation efficiency.

[0090] To prevent scaling, a two-stage temperature interlock control system ensures stable operation of the atomizing equipment and evaporator. This system monitors the flue gas temperature at key monitoring points in the evaporator in real time and calculates critical flue gas temperature values. When the critical flue gas temperature is too high, the closed-loop water input pipeline automatically opens, injecting 0.15-0.2 MPa of closed-loop water into the atomizing equipment. This lowers the temperature of the wastewater entering the two-stage series nozzles, preventing the wastewater from instantly vaporizing and causing scale formation due to high-load, high-temperature flue gas. Conversely, when the critical flue gas temperature is too low, the closed-loop water input pipeline automatically closes to prevent the wastewater temperature from affecting subsequent evaporation. Through this regulation, the evaporator tower wall temperature can be stabilized at around 180℃, meeting evaporation requirements while mitigating scaling risks. Simultaneously, the lubricating oil pump continuously provides 0.1-0.2 MPa of lubricating oil to the drive motor of the atomizing equipment, ensuring long-term stable motor operation.

[0091] In the ash and slag treatment stage, the solid ash and slag precipitated in the evaporation tower falls into the ash storage tank through the bottom ash discharge pipe for temporary storage. Then, compressed air at 0.6-0.7 MPa is introduced to pneumatically convey the solid ash and slag in the ash storage tank to the slag bin for centralized storage, completing the final disposal of the ash and slag. If the ash and slag clump due to poor atomization, the short connector at the bend in the pipe between the ash storage tank and the slag bin can be quickly removed and cleaned. The ash cleaning hole at the bottom of the ash storage tank can also promptly remove internal ash accumulation, preventing blockages that could affect the continuous operation of the entire system.

[0092] In summary, the full-load wastewater zero-discharge evaporation system provided in this embodiment addresses the pain points of wastewater treatment in thermal power plants. Through integrated design of flue gas pressurization adaptation, two-stage temperature control, and anti-scaling and anti-clogging, it has at least the following beneficial effects:

[0093] Firstly, relying on the design of one booster fan for operation and one for standby, the differential pressure of flue gas can be effectively increased when the unit is under low load. Combined with the precise adjustment of the flue gas damper under high load, the stable operation of zero wastewater discharge under full load conditions can be achieved. This effectively solves the problems of low load cut-off and high load inefficiency in traditional treatment methods, and meets the environmental protection requirements of thermal power plants at all times.

[0094] Secondly, through the two-stage temperature interlock control of closed water and flue gas dampers, the wastewater temperature of the atomizing equipment and the wall temperature of the evaporation tower are stabilized at around 180℃, which effectively avoids the problem of scaling of the atomizing body caused by the instantaneous vaporization of wastewater under high load. At the same time, the setting of two-stage series nozzles can ensure atomization efficiency, greatly reduce the frequency of downtime for cleaning, and thus significantly reduce operation and maintenance costs.

[0095] Thirdly, the short connectors at the bends in the pipes between the ash storage tank and the slag bin, as well as the cleaning holes at the bottom of the ash storage tank, can quickly address the problem of ash and slag clumping and blockage. Combined with the pneumatic conveying of compressed air, this can significantly improve the reliability of the ash and slag handling process.

[0096] Fourth, the overall system utilizes the waste heat from the air preheater flue gas as a heat source, which can balance environmental benefits and energy conservation, and significantly improve the operational stability and environmental protection and energy conservation of the zero-discharge stage of thermal power plant wastewater.

[0097] Based on the same general inventive concept, this invention also protects a full-load wastewater zero-discharge evaporation method. The full-load wastewater zero-discharge evaporation method provided by this invention is described below. The full-load wastewater zero-discharge evaporation method described below can be referred to in correspondence with the full-load wastewater zero-discharge evaporation system described above.

[0098] like Figure 4 As shown, this embodiment of the invention also provides a full-load wastewater zero-discharge evaporation method. This method is based on the full-load wastewater zero-discharge evaporation system provided in the above embodiments, and specifically includes the following steps:

[0099] Step 310: Introduce flue gas into the evaporator tower through the flue gas circulation channel via the flue gas recirculation subsystem.

[0100] Step 320: The wastewater to be treated is atomized through the wastewater atomization subsystem and then fed into the evaporation tower so that the atomized wastewater to be treated comes into contact with the flue gas.

[0101] Step 330: Collect the solid ash residue precipitated during the evaporation process through the ash conveying subsystem, and discharge the ash residue using compressed air.

[0102] Step 340: Obtain unit load data during the evaporation process through the interlocking control subsystem, and based on the unit load data, perform interlocking control on at least some key components of the flue gas recirculation subsystem, wastewater atomization subsystem, and ash conveying subsystem.

[0103] The specific implementation of each step in the methods described in the above embodiments has been described in detail in the embodiments of the relevant systems, and will not be elaborated further here.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A full-load wastewater zero-discharge evaporation system, characterized in that, include: Evaporation tower and the flue gas circulation subsystem, wastewater atomization subsystem, ash conveying and treatment subsystem and interlocking control subsystem connected to the evaporation tower; The interlocking control subsystem is connected to the flue gas recirculation subsystem, the wastewater atomization subsystem, and the ash conveying and treatment subsystem, respectively. The flue gas recirculation subsystem is used to introduce flue gas into the evaporator through the flue gas flow channel; The wastewater atomization subsystem is used to atomize the wastewater to be treated and then input it into the evaporation tower so that the atomized wastewater to be treated comes into contact with the flue gas. The ash conveying subsystem is used to collect the solid ash residue precipitated during the evaporation process and to discharge the ash residue using compressed air. The interlocking control subsystem is used to acquire unit load data during the evaporation process, and based on the unit load data, to perform interlocking control on at least some key components of the flue gas circulation subsystem, the wastewater atomization subsystem, and the ash conveying and treatment subsystem.

2. The full-load wastewater zero-discharge evaporation system according to claim 1, characterized in that, The flue gas recirculation subsystem includes: an air preheater inlet pipe, a booster fan, and an air preheater outlet pipe; The air preheater inlet pipe is connected to the booster fan, the booster fan is connected to the flue gas inlet at the top of the evaporator, and the air preheater outlet pipe is connected to the flue gas outlet at the bottom of the evaporator.

3. The full-load wastewater zero-discharge evaporation system according to claim 1, characterized in that, The wastewater atomization subsystem includes: a closed-loop water inlet pipeline, a lubricating oil pump, a cooler, and atomization equipment; The closed-loop water input pipeline is connected to the lubricating oil pump and the cooler respectively. The lubricating oil pump and the cooler are both connected to the atomizing device, which is connected to the atomizing port at the top of the evaporation tower.

4. The full-load wastewater zero-discharge evaporation system according to claim 3, characterized in that, The atomizing device includes: a shower-type distributor, an atomizing body, a drive motor, and two-stage series nozzles; The shower-type distributor is used to divide the wastewater to be treated into fine streams and send them into the atomizing body; the atomizing body, driven by the drive motor, atomizes the fine streams into droplets through the two-stage series nozzles and sends them into the evaporation tower.

5. The full-load wastewater zero-discharge evaporation system according to claim 1, characterized in that, The ash conveying and processing subsystem includes: ash discharge pipeline, ash storage tank, air supply pipeline, ash conveying pipeline, and slag bin; One end of the ash discharge pipe is connected to the bottom of the evaporation tower, the other end of the ash discharge pipe, the gas supply pipe, and one end of the ash supply pipe are all connected to the ash storage tank, and the other end of the gas supply pipe is connected to the slag bin. The ash discharge pipe is used to send the solid ash residue precipitated after the evaporation of the wastewater to be treated in the evaporation tower to the ash storage tank. The air supply pipe is used to send compressed air into the ash storage tank so that the solid ash residue can be transported by pneumatic force through the ash discharge pipe to the slag bin for storage.

6. The full-load wastewater zero-discharge evaporation system according to claim 5, characterized in that, The ash delivery pipeline is equipped with at least three short connectors, and the bottom of the ash storage tank is provided with multiple cleaning holes for cleaning ash slag clumps inside the tank.

7. The full-load wastewater zero-discharge evaporation system according to claim 1, characterized in that, An inlet flue gas baffle is installed at the connection between the evaporator tower and the inlet of the flue gas circulation channel; The interlocking control subsystem includes a controller, which is used for: If the unit load data is higher than the set upper limit of the load, the opening of the inlet flue gas damper is reduced, and the opening of the inlet flue gas damper is above the set lower limit of the opening.

8. The full-load wastewater zero-discharge evaporation system according to claim 7, characterized in that, The interlocking control subsystem also includes: multiple temperature sensors, which are respectively located at multiple key monitoring points of the evaporation tower, and all of the multiple temperature sensors are connected to the controller; The controller is also used for: Acquire temperature data and unit load data from various key monitoring points collected by the multiple temperature sensors, and determine the key flue gas temperature value inside the evaporator based on the temperature data; If the critical flue gas temperature value is higher than the set upper temperature limit, the closed water input pipeline in the wastewater atomization subsystem is controlled to be opened. If the critical flue gas temperature value is lower than the set lower limit, the closed water input pipeline in the wastewater atomization subsystem is shut off.

9. The full-load wastewater zero-discharge evaporation system according to claim 7, characterized in that, The interlocking control subsystem also includes: a pressure sensor, which is located at two air preheaters near the air preheater inlet pipeline, and the pressure sensor is connected to the controller; The controller is also used for: Acquire the pressure data collected by the pressure sensor, and determine the air preheater differential pressure value based on the pressure data; If the air preheater differential pressure value is lower than the set differential pressure lower limit, and / or the unit load data is lower than the set load lower limit, then all subsystems will be controlled to stop operating.

10. A method for zero-discharge evaporation of wastewater under full load, characterized in that, Based on the full-load wastewater zero-discharge evaporation system as described in any one of claims 1 to 9, the method includes: Flue gas is introduced into the evaporator through the flue gas circulation channel via the flue gas recirculation subsystem; The wastewater to be treated is atomized by the wastewater atomization subsystem and then fed into the evaporation tower so that the atomized wastewater to be treated comes into contact with the flue gas. The solid ash residue precipitated during the evaporation process is collected by the ash handling subsystem and discharged using compressed air; The unit load data during the evaporation process is obtained through the interlocking control subsystem, and based on the unit load data, at least some key components of the flue gas circulation subsystem, the wastewater atomization subsystem, and the ash conveying and treatment subsystem are interlocked and controlled.

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