Desulfurization wastewater flue gas atomization drying process and system

Abstract

The present application relates to coal-fired power plant wastewater discharge and flue gas waste heat utilization technical field, disclose a kind of desulfurization wastewater flue atomization drying process and system, solve the technical problems of high investment, complex operation of traditional desulfurization wastewater treatment, and flue ash, nozzle fouling leads to equipment wear, desulfurization efficiency decline.This process relies on special system implementation, by desulfurization wastewater is sequentially completed conditioning clarification, emulsification modulation, flue atomization drying, water gas mixing strengthening etc., cooperate ash, on-line intelligent detection and regulation of moisture, realize wastewater moisture evaporation, salt solid waste;Supporting system is composed of flue gas treatment, wastewater treatment, flue direct injection, intelligent detection control four units, each unit is linked to ensure that the process is efficiently implemented, but also can effectively inhibit flue ash and nozzle fouling, realize desulfurization wastewater zero discharge.The present application improves desulfurization efficiency and equipment service life, reduces operating energy consumption, adapts to the development needs of coal-fired power plant "waste treatment".

Description

Technical Field

[0001] This invention belongs to the technical field of wastewater discharge and flue gas waste heat utilization in coal-fired power plants, specifically relating to a desulfurization wastewater flue gas atomization drying process and system. Background Technology

[0002] In recent years, with increasingly stringent national requirements for industrial wastewater treatment, desulfurization wastewater from coal-fired boilers has become a challenging issue due to its complex composition, high salt content (total dissolved solids can reach 20,000~50,000 mg / L), and high chloride ion content (5,000~20,000 mg / L). Traditional desulfurization wastewater treatment often employs a chemical precipitation + evaporation crystallization technical route. This route requires an initial investment of approximately 80~150 yuan / ton of wastewater, with system operating costs reaching 30~50 yuan / ton of wastewater. Furthermore, it suffers from drawbacks such as complex operation, difficult and costly salt sludge disposal, making it unsuitable for the actual operational needs of coal-fired power plants.

[0003] Existing technologies include atomizing and drying desulfurization wastewater in the flue gas duct before the dust collector or in a bypass evaporator. This method utilizes the waste heat of the flue gas to evaporate the water, while salts and heavy metals are captured with the fly ash, achieving "end-of-pipe solid waste treatment," which aligns with the power plant's requirements for "waste treatment with waste" and comprehensive utilization of ash and slag. However, this treatment method still has many problems in practical applications:

[0004] Powdered solid particles generated during combustion in coal-fired power plant boilers tend to accumulate in horizontal flues. When the ash accumulation thickness exceeds 3mm, the flue flow area decreases by 10% to 20%, the flue gas velocity increases by 15% to 30%, and the wear of the flue and its components is aggravated. In severe cases, it can cause coking in the flue, reducing boiler thermal efficiency by 5% to 8%, and significantly reducing boiler operating efficiency and safety. Current flue ash cleaning methods mostly use timed and quantitative soot blowing, relying on experience to judge the timing of soot blowing. This method cannot intelligently sense the ash accumulation, and it is easy to cause insufficient or excessive soot blowing. Insufficient soot blowing cannot effectively remove ash, while excessive soot blowing will cause cavitation on the heating surface, shortening the service life of the equipment by 30% to 40%. At the same time, the annual waste of manpower and material resources can reach tens of thousands of yuan.

[0005] Scaling is a common problem in desulfurization wastewater atomizing nozzles. Scaling can reduce desulfurization efficiency from 90% to about 80%, while increasing system resistance and fan energy consumption by 15%. Scaling can also cause corrosion to the nozzles and surrounding equipment at a rate of more than 0.1 mm per year, shortening the equipment's lifespan by 50%. Severe scaling requires shutdown and cleaning every 2 to 3 months, with a single cleaning costing approximately 10,000 to 30,000 yuan. Annual downtime losses can reach hundreds of thousands of yuan, resulting in huge economic losses.

[0006] The mixing efficiency of desulfurization wastewater with flue gas after atomization is low, and the drying rate is slow. If the moisture content in the flue exceeds 12%, it will further aggravate equipment corrosion and flue blockage. The existing process lacks real-time detection and precise control of the moisture content in the flue, and cannot adjust the wastewater injection volume according to the flue gas status. At the same time, the supporting control system only has simple data acquisition and equipment start-up and shutdown functions, without professional algorithm model support, resulting in low control accuracy and slow response speed, and failing to achieve intelligent control of the entire process.

[0007] Therefore, developing a desulfurization wastewater flue gas atomization drying process and system that can achieve efficient treatment of desulfurization wastewater while solving the problems of flue gas ash accumulation and nozzle scaling has become an urgent technical problem to be solved in this field. Summary of the Invention

[0008] The purpose of this invention is to provide a desulfurization wastewater flue gas atomization drying process and system to solve the technical problems of high investment, complex operation, unintelligent flue gas ash cleaning, nozzle scaling leading to equipment wear and reduced desulfurization efficiency, and low control system precision in traditional desulfurization wastewater treatment.

[0009] To achieve the above-mentioned objectives, the technical solution adopted by this invention is: a desulfurization wastewater flue gas atomization drying process, comprising the following steps:

[0010] S1. Flue gas conveying and preliminary treatment: The flue gas generated by the coal-fired boiler is preheated by the air preheater and then enters the flue. The flue gas is conveyed to the electrostatic precipitator for dust removal. The flue gas after dust removal enters the flue gas desulfurization equipment for desulfurization. The clean flue gas after desulfurization is conveyed to the chimney for emission into the air through the flue.

[0011] S2. Sludge dewatering and wastewater collection: The sludge produced by the flue gas desulfurization equipment is sent to the sludge dewatering equipment for dewatering treatment. The clear liquid produced by dewatering is used as desulfurization wastewater and is pumped to the wastewater conditioning and clarification equipment by the wastewater pump.

[0012] S3. Wastewater conditioning and clarification: Water treatment agents are added to the wastewater conditioning and clarification equipment through a water treatment dosing device and a water treatment agent dosing pump. After the desulfurization wastewater and water treatment agents are mixed and flocculated in the coagulation zone by an agitator for 10-20 minutes, they enter the bottom cone-shaped sedimentation zone and are left to settle for 1.5-2.5 hours to remove more than 85% of suspended solids and more than 60% of soluble salts from the wastewater. The clear liquid at the top is then transported to the intermediate conditioning tank.

[0013] S4. Wastewater emulsification and conditioning: Polyoxyethylene ether emulsifier (dosage is 0.08‰~0.12‰ of wastewater volume) is added to the intermediate conditioning tank through an emulsifier dosing device and an emulsifier dosing pump. The emulsifier and supernatant are mixed in the mixing zone by an emulsifier mixer for 0.5~1.5 hours, and the mixing uniformity reaches more than 95%, resulting in emulsified wastewater, which effectively inhibits scaling of subsequent nozzles.

[0014] S5. Flue gas atomization drying: The atomizing pump delivers the emulsified wastewater to the nozzle at a pressure of ≥0.5MPa. Compressed air mixes with the emulsified wastewater at the nozzle and atomizes it into droplets with a particle size of 50~100μm. The atomized droplets are then sprayed into the flue gas duct before the electrostatic precipitator. The atomized droplets are adapted to the flue gas flow rate of 10~15m / s in the flue gas duct. The atomized wastewater comes into contact with the high-temperature flue gas of 280~350℃. The water evaporates rapidly within 1~3s and is carried away with the flue gas. The salt is precipitated and suspended with the fly ash in the flue gas.

[0015] S6. Enhanced water-air mixing: The mixed airflow of atomized wastewater and flue gas passes through the steel baffle plate (bending angle 40°~50°) and / or other baffle components behind the nozzle, the flow field is optimized, the water-air mixing rate is increased by more than 40%, the wastewater drying efficiency is increased to more than 99%, and the accumulation of ash and scale in the flue is suppressed.

[0016] S7. Intelligent Detection and Control: The ash accumulation detection instrument (detection accuracy ±0.1mm) detects the ash content in the flue and spoiler in real time and transmits the data to the intelligent control system. The intelligent control system predicts the ash accumulation trend using a dedicated algorithm model and adjusts the operating frequency and intensity of the low-frequency sootblower based on real-time ash accumulation data and prediction results to control the ash accumulation thickness below 3mm. The moisture detection instrument (detection accuracy ±0.5%) detects the moisture content of the flue gas in real time. The intelligent control system dynamically adjusts the delivery volume of the atomizing pump based on the moisture data using a closed-loop control algorithm to stably control the flue gas moisture content between 8% and 10%. The intelligent control system also achieves intelligent equipment linkage and multi-level risk warning, with an algorithm response delay ≤0.5s and a control accuracy of ±2%.

[0017] S8. Salt solid waste treatment: Fly ash carrying precipitated salt enters the electrostatic precipitator with the flue gas. After being captured and separated by the electrostatic precipitator, the salt capture rate can reach more than 98%, realizing the solid waste treatment of salt and avoiding the generation of separate salt hazardous waste. The captured fly ash can be comprehensively utilized together with the fly ash of the power plant.

[0018] This invention also provides a desulfurization wastewater flue gas atomization drying system for implementing the above-mentioned desulfurization wastewater flue gas atomization drying process, comprising a flue gas treatment unit, a wastewater treatment unit, a flue gas direct injection unit, and an intelligent detection and control unit. These four units work in synergy to provide integrated equipment support for process implementation.

[0019] Flue gas treatment unit: includes a coal-fired boiler, air preheater, flue, electrostatic precipitator, flue gas desulfurization equipment, chimney and sludge dewatering equipment. The coal-fired boiler, air preheater, electrostatic precipitator, flue gas desulfurization equipment and chimney are connected in sequence through the flue. The sludge dewatering equipment is connected to the flue gas desulfurization equipment and is used to dewater the sludge generated by the flue gas desulfurization equipment, provide flue gas medium for the process and collect desulfurization wastewater.

[0020] The wastewater treatment unit includes a wastewater pump, wastewater conditioning and clarification equipment, a water treatment dosing device, a water treatment chemical dosing pump, an intermediate conditioning tank, an emulsifier dosing device, and an emulsifier dosing pump. The wastewater pump is connected at both ends to sludge dewatering equipment and the wastewater conditioning and clarification equipment, respectively. The water treatment dosing device is connected to the wastewater conditioning and clarification equipment via the water treatment chemical dosing pump. The wastewater conditioning and clarification equipment includes interconnected coagulation and sedimentation zones. The coagulation zone is equipped with an agitator, and the sedimentation zone is a clarification tank with a cone-shaped bottom. The intermediate conditioning tank is connected to the wastewater conditioning and clarification equipment and contains a mixing zone with an emulsifier mixing agitator. The emulsifier dosing device is connected to the intermediate conditioning tank via an emulsifier dosing pump. The water treatment dosing device is used to dilute and mix water treatment chemicals, and the emulsifier dosing device is used to dilute and mix emulsifiers. The dosing accuracy of chemicals and emulsifiers can reach ±0.5‰. This unit achieves conditioning, clarification, and emulsification of desulfurization wastewater.

[0021] The direct injection unit for flue gas includes an atomizing pump, compressed air, nozzles, baffles, and / or other baffle components. The atomizing pump is a high-pressure plunger pump with a rated pressure ≥0.5MPa. Its two ends are connected to the intermediate conditioning water tank and the nozzles, respectively. The nozzles are dual-fluid atomizing nozzles and are located in the flue gas before the electrostatic precipitator. The compressed air is connected to the nozzles. The baffles are steel folded plates (folded at an angle of 40°~50°) and are arranged in sequence with the baffle components in the flue gas after the nozzles. This unit realizes the atomization and injection of desulfurization wastewater and the enhancement of water-air mixing.

[0022] The intelligent detection and control unit includes an ash accumulation detection instrument, a moisture detection instrument, an acoustic soot blowing device, and an intelligent control system. The ash accumulation detection instrument and moisture detection instrument are both located inside the flue. The acoustic soot blowing device is a low-frequency acoustic soot blower (operating frequency 100~300Hz), corresponding to the flue. The intelligent control system is electrically connected to the ash accumulation detection instrument, moisture detection instrument, acoustic soot blowing device, wastewater pump, water treatment chemical dosing pump, emulsifier dosing pump, and atomizing pump. Its hardware architecture includes an industrial control host, a data acquisition module (DAQ), a communication module, an actuator drive module, and a human-machine interface terminal. The communication module supports Modbus. It adopts mainstream industrial communication protocols such as sRTU / TCP, Profinet, and OPCUA to achieve seamless integration with testing instruments and field equipment. Its software layer is equipped with six core intelligent functional modules: data acquisition and preprocessing module, intelligent ash accumulation control module, moisture closed-loop control module, intelligent equipment linkage module, risk warning and alarm module, and data management and visualization module. It also incorporates three exclusive algorithm models: an ash accumulation prediction algorithm based on LSTM+XGBoost, a soot blowing control algorithm based on fuzzy PID, and a moisture control algorithm based on incremental PID, providing core technical support for intelligent detection and control of the entire process.

[0023] Dedicated algorithm models and application methods for control systems

[0024] The intelligent control system of this invention is a core supporting module for process implementation. Its three built-in proprietary algorithm models are highly compatible with the desulfurization wastewater flue gas atomization drying process, including clearly defined algorithm formulas, parameter settings, and on-site application methods. This enables accurate prediction of ash accumulation, on-demand control of soot blowing, and closed-loop stable control of moisture content. The following is a detailed description of each algorithm model:

[0025] (I) Ash Accumulation Prediction Algorithm Based on LSTM+XGBoost

[0026] 1. Core formula of the algorithm

[0027] This algorithm uses a hybrid model that combines LSTM and XGBoost. First, LSTM is used to capture the time-series features of the ash accumulation data, and then XGBoost is used to correct the prediction results and improve the prediction accuracy.

[0028] (1) LSTM core calculation formula

[0029] LSTM extracts features from time-series data through input gates, forget gates, and output gates. The core formula is as follows:

[0030] Forgotten Gate:

[0031] in, Output for the forget gate. It is the Sigmoid activation function. Here is the forget gate weight matrix. This is the output of the hidden layer from the previous time step. Input data for the current moment. Forget gate bias term;

[0032] Input Gate:

[0033]

[0034]

[0035] in, For input gate output, Candidate cell state, The hyperbolic tangent activation function is used. , For the corresponding weight matrix, , For the corresponding bias term;

[0036] Cell status update:

[0037]

[0038] in, The current cell state, This represents the cell state at the previous moment. Dot product of elements;

[0039] Output gate:

[0040] in, For output gate output, This is the output of the hidden layer at the current moment. This is the output gate weight matrix. This is the output gate bias term.

[0041] (2) XGBoost core calculation formula

[0042] XGBoost is an ensemble learning algorithm that corrects LSTM predictions by integrating multiple regression trees. Its core formula is as follows:

[0043] Objective function:

[0044]

[0045] in, The loss function (using mean squared error)

[0046] This is a regularization term to prevent overfitting;

[0047] Regular terms:

[0048] in, The penalty term is for the number of leaf nodes. To regress the number of tree nodes, This is the weight decay coefficient. The weights of the leaf nodes;

[0049] Tree generation:

[0050]

[0051] in, Let be the predicted value for the k-th tree. It is the sum of the predictions from the first k-1 trees.

[0052] 2. Algorithm parameter settings

[0053] LSTM layer: Input dimension is 4 (ash thickness, flue gas velocity, flue gas temperature, wastewater injection volume), number of hidden layer nodes is 64, number of layers is 2, dropout coefficient is 0.2, optimizer is Adam, learning rate is 0.001, number of training rounds is 100;

[0054] XGBoost layer: learning rate 0.01, tree depth 6, number of leaf nodes 32, number of iterations 200, regularization term γ=0.1, λ=1;

[0055] Predicted output: flue ash thickness and ash risk value for the next 1h / 4h / 8h (risk value = ash thickness / 3mm × 100, full value 100).

[0056] 3. On-site application methods

[0057] Data input: The real-time ash thickness (mm) collected by the ash accumulation detection instrument, the flue gas velocity (m / s) collected by the flue gas velocity sensor, the flue gas temperature (°C) collected by the flue gas temperature sensor, and the wastewater injection rate (m³ / h) collected by the atomizing pump flow sensor are used as the algorithm input data. After data preprocessing (normalization, outlier removal), the data is imported into the model.

[0058] Model training: Before the system is put into operation, the LSTM+XGBoost model is trained using historical operating data of the power plant (no less than 6 months). After training, the model is validated using a test set to ensure that the prediction accuracy is ≥95%.

[0059] Real-time prediction: When the system is running normally, the algorithm imports input data in real time at a sampling frequency of 5 seconds and outputs the predicted values ​​of ash accumulation thickness and ash accumulation risk value for the next 1 hour / 4 hours / 8 hours.

[0060] Application of results: The prediction results are transmitted to the ash accumulation intelligent control module. If the predicted ash accumulation risk value is ≥60 (medium risk), the low-frequency pre-blowing of the acoustic soot blowing device is triggered in advance; if the predicted risk value is ≥80 (high risk), the high-frequency strong soot blowing is triggered immediately to achieve early prevention and control of ash accumulation.

[0061] (II) Intelligent control algorithm for soot blowing based on fuzzy PID

[0062] 1. Core formula of the algorithm

[0063] This algorithm combines fuzzy control with traditional PID control, using a fuzzy rule base to optimize the proportional coefficient of the PID controller. Integral coefficient Differential coefficients Online self-tuning enables precise control of soot blowing frequency and intensity. The core formula is as follows:

[0064] (1) Traditional PID control formula

[0065]

[0066]

[0067] in, This refers to the soot blowing control amount (soot blowing frequency / intensity increment). The current dust accumulation thickness deviation (set value 3mm - actual dust accumulation thickness). , This represents the deviation at the first 1 and 2 time points.

[0068] (2) Fuzzy control self-tuning formula

[0069] Determine the coefficient correction amount using a fuzzy rule base. , , To achieve online updating of PID coefficients:

[0070]

[0071] in, , , The initial coefficients for the PID controller (determined through on-site debugging): =2.5, =0.8, =0.5), , , This is the coefficient correction amount for the fuzzy control output.

[0072] 2. Algorithm parameter settings

[0073] Fuzzy domain:

[0074] deviation The domain of discourse is [0,3] (mm).

[0075] Deviation change rate The domain of discourse is [0, 0.5] (mm / s).

[0076] , , The domain of discourse for all of them is [-1,1].

[0077] Fuzzy subsets: Each subset is divided into 7 subsets: {NB (negative large), NM (negative medium), NS (negative small), ZO (zero), PS (positive small), PM (positive medium), PB (positive large)}.

[0078] Soot blowing control parameters: Soot blowing frequency domain [50, 300] (Hz), soot blowing intensity domain [30, 100] (%), both correlated with PID control parameters. Linear mapping;

[0079] Fuzzy rules: A total of 49 fuzzy rules were defined (such as...) hour, ), covering all scenarios involving dust accumulation deviation and deviation change rate.

[0080] 3. On-site application methods

[0081] Deviation calculation: Real-time acquisition of actual ash accumulation thickness in the flue, calculation of the deviation from the set value (3mm) and the rate of change of deviation ;

[0082] Fuzzy reasoning: and After fuzzification, the data is imported into a fuzzy rule base, and the PID coefficient correction is obtained through inference. , , Update the PID coefficients;

[0083] Control Quantity Calculation: Calculate the soot blowing control quantity based on the updated PID coefficients. And linearly map it to the increments of blowing frequency and intensity;

[0084] On-site execution: The blowing frequency and intensity commands are sent to the acoustic soot blowing device to achieve on-demand soot blowing; for example, when the actual soot thickness is 2mm, =1mm, When the blowing speed is 0.1 mm / s, the output blowing frequency is 150 Hz and the blowing intensity is 50% after fuzzy PID calculation; when the actual dust accumulation thickness is 2.8 mm, =0.2mm, When the speed is 0.3 mm / s, the output blowing frequency is 250 Hz and the blowing intensity is 90%.

[0085] (III) Moisture Closed-Loop Control Algorithm Based on Incremental PID

[0086] 1. Core formula of the algorithm

[0087] This algorithm employs incremental PID control, eliminating integral accumulation error, and features fast response, strong anti-interference capability, and suitability for real-time closed-loop control of flue gas moisture. The core formula is as follows:

[0088]

[0089]

[0090]

[0091] in:

[0092] This is the increment for the flow rate regulation of the atomizing pump (m³ / h).

[0093] The incremental PID tuning coefficients (determined through on-site debugging): );

[0094] The current moisture deviation is (upper limit of 9% - actual moisture content), the set value range is 8%~10%, and the middle value of 9% is taken as the core set value;

[0095] , This represents the moisture content deviation at the first 1 and 2 time points;

[0096] This is the output flow rate of the atomizing pump (m³ / h). This represents the output flow rate of the atomizing pump at the previous moment.

[0097] 2. Algorithm parameter settings

[0098] Regulation dead zone: moisture deviation When the flow rate is ≤0.5%, no flow regulation is performed to avoid frequent start-ups and shutdowns of the equipment;

[0099] Flow rate upper and lower limits: output flow rate of the atomizing pump It is adapted to the daily treatment capacity requirements of power plant desulfurization wastewater;

[0100] Control step size: Increment of single flow control This enables stepped adjustment and ensures system stability.

[0101] Sampling frequency: 5s / time, synchronized with the sampling frequency of the moisture detection instrument.

[0102] 3. On-site application methods

[0103] Deviation Acquisition: The moisture detection instrument collects the moisture content of the flue gas in real time and calculates the deviation from the core set value (9%). ,like If the flow rate is ≤0.5%, the system enters the control dead zone and maintains the current flow rate of the atomizing pump.

[0104] Calculation of control amount: If >0.5%, calculate the flow control increment according to the incremental PID formula. And limit the amplitude by combining the upper and lower limits of the flow rate and the control step size;

[0105] Flow rate adjustment: Adjust the calculated output flow rate of the atomizing pump. The signal is sent to the frequency converter of the atomizing pump to adjust the speed of the atomizing pump and achieve precise control of the wastewater injection volume.

[0106] Closed-loop feedback: After adjustment, the new moisture content is collected in real time, and the deviation is recalculated, forming a closed-loop control of "detection-calculation-adjustment-feedback"; for example: when the actual moisture content = 10.5%, =−1.5%, calculated by the algorithm, =−0.2m³ / h, the atomizing pump flow rate decreased from 2.1m³ / h to 1.9m³ / h, and the moisture content dropped back to 9.3% within 1 minute, entering the stable range.

[0107] The beneficial effects of this invention are mainly reflected in:

[0108] 1. The process and system of this invention are highly compatible. The process is implemented based on a dedicated system, and all equipment works together to ensure high efficiency and stability throughout the desulfurization wastewater treatment process, achieving 100% zero discharge of desulfurization wastewater. The treatment route of "conditioning and clarification + emulsification and modulation + flue gas atomization drying" is adopted, which utilizes the waste heat of flue gas to evaporate the water in the wastewater. The salt capture rate can reach more than 98%, realizing the solidification of salt and avoiding the generation of separate hazardous salt waste, which meets the "waste treatment" requirements of coal-fired power plants. Compared with the traditional chemical precipitation + evaporation crystallization route, the initial investment of this process is reduced by 60% to 70%, and the operating cost is reduced to 8 to 15 yuan / ton of wastewater, which significantly reduces the wastewater treatment cost of coal-fired power plants.

[0109] 2. Effectively solves the industry pain point of nozzle scaling. The process removes more than 85% of suspended solids and more than 60% of salts through conditioning and clarification, reducing scaling substances at the source. Then, emulsification extends the scaling time of nozzles by more than 10 times (from the original 2-3 months to 2-3 years). The dual-fluid atomizing nozzle and emulsifier dosing device in the supporting system work together to further reduce the probability of scaling. Ultimately, the utilization rate of desulfurizer is increased from 65%-70% to more than 80%, the system resistance is reduced by 60%, the fan energy consumption is reduced by 15%-20%, the equipment corrosion rate is reduced to less than 0.01mm per year, the service life of equipment is extended by more than 50%, the number of shutdowns for cleaning is reduced, and the annual downtime losses are reduced by hundreds of thousands of yuan.

[0110] 3. Achieve accurate prediction and on-demand control of flue ash accumulation. Through the ash accumulation prediction algorithm based on LSTM+XGBoost, the ash accumulation prediction accuracy is ≥95%, and the ash accumulation development trend can be predicted 1~8 hours in advance to avoid flue blockage caused by excessive ash accumulation. Combined with the intelligent control algorithm of soot blowing based on fuzzy PID, the online self-tuning of soot blowing frequency and intensity is realized, the ash cleaning efficiency is improved by more than 50%, the equipment wear rate is reduced by 40%~50%, and the ash accumulation thickness is stably controlled below 3mm, effectively preventing safety accidents such as flue blockage, heat exchange surface wear, and tube rupture, and the boiler thermal efficiency is improved by 5%~8%.

[0111] 4. Achieve closed-loop, precise, and stable control of flue gas moisture content. Through an incremental PID-based closed-loop moisture control algorithm, a complete closed loop of "detection-calculation-adjustment-feedback" is constructed. The algorithm response delay is ≤0.5s, and the control accuracy is ±2%, stably controlling the flue gas moisture content at 8%~10%. This avoids equipment corrosion and flue gas blockage caused by excessive moisture, or the impact of insufficient moisture on wastewater treatment efficiency. The equipment failure rate is reduced by more than 60%, improving the stability of system operation.

[0112] 5. The intelligent control system's algorithm model is highly compatible with the process. Each algorithm contains clear formulas, parameters, and on-site application methods, allowing for rapid commissioning without complex debugging. The algorithm has a fast response speed and high control accuracy, realizing full-process intelligentization from data acquisition and predictive analysis to equipment control and risk warning. The system can achieve unattended operation, reducing manual operation and maintenance costs by more than 70%. At the same time, the historical data output by the algorithm can provide accurate decision support for power plant process optimization and equipment maintenance. Attached Figure Description

[0113] Figure 1 This is a schematic diagram of the desulfurization wastewater flue gas atomization drying system of the present invention;

[0114] In the diagram: 1. Coal-fired boiler; 2. Air preheater; 3. Flue; 4. Electrostatic precipitator; 5. Flue gas desulfurization equipment; 6. Chimney; 7. Sludge dewatering equipment; 8. Wastewater pump; 9. Agitator; 10. Wastewater conditioning and clarification equipment; 11. Water treatment dosing device; 12. Water treatment chemical dosing pump; 13. Emulsifier dosing device; 14. Emulsifier dosing pump; 15. Intermediate conditioning water tank; 16. Atomizing pump; 17. Compressed air; 18. Nozzle; 19. Ash accumulation detection instrument; 20. Baffle plate; 21. Baffle component; 22. Acoustic soot blowing device; 23. Moisture detection instrument; 24. Sedimentation zone; 25. Coagulation zone; 27. Emulsifier mixing agitator. Detailed Implementation

[0115] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment takes a desulfurization wastewater treatment project of a 600MW coal-fired power plant as the application scenario. The daily production of desulfurization wastewater of the power plant is 50m³, the total dissolved solids content of the wastewater is 35000mg / L, the chloride ion content is 12000mg / L, and the suspended solids content is 800mg / L.

[0116] System Setup

[0117] The desulfurization wastewater flue gas atomization drying system of the present invention includes a flue gas treatment unit, a wastewater treatment unit, a flue gas direct injection unit, and an intelligent detection and control unit. The intelligent detection and control unit has a built-in proprietary algorithm model, and its specific configuration is as follows:

[0118] 1. Flue Gas Treatment Unit: Coal-fired boiler 1 is a 600MW coal-fired unit boiler. Flue gas duct 3 has a diameter of 4.5m and the flue gas velocity is controlled at 12m / s. Coal-fired boiler 1, air preheater 2, electrostatic precipitator 4, flue gas desulfurization treatment equipment 5, and chimney 6 are connected sequentially through flue gas duct 3. Sludge dewatering equipment 7 is a plate and frame filter press, which is connected to flue gas desulfurization treatment equipment 5. It is equipped with flue gas velocity sensor (accuracy ±0.1m / s) and flue gas temperature sensor (accuracy ±1℃).

[0119] 2. Wastewater Treatment Unit: Wastewater pump 8 is a variable frequency centrifugal pump with a flow rate adjustment range of 0~5 m³ / h; Wastewater conditioning and clarification equipment 10 has an effective volume of 20 m³, including a coagulation zone 25 and a bottom conical sedimentation zone 24. The coagulation zone 25 is equipped with an agitator 9 (speed 0~500 r / min); Water treatment dosing device 11 and emulsifier dosing device 13 are both stirred dosing tanks, and the matching water treatment chemical dosing pump 12 and emulsifier dosing pump 14 are precision metering pumps with a dosing accuracy of ±0.5‰; Intermediate conditioning water tank 15 has an effective volume of 10 m³ and is equipped with an emulsifier mixing agitator 27 (speed 0~300 r / min).

[0120] 3. Flue gas direct injection unit: The atomizing pump 16 is a high-pressure variable frequency plunger pump with a rated pressure of 1.0MPa and a matching flow sensor (accuracy ±0.5%); the nozzle 18 is a dual-fluid atomizing nozzle, located in the flue gas 3 15m before the electrostatic precipitator 4; the compressed air 17 has a stable pressure of 0.7MPa; the baffle 20 is a 45° steel folding plate, and the baffle component 21 is a steel guide column, both of which are located in the flue gas 3 behind the nozzle 18; the sonic soot blowing device 22 is a low-frequency sonic soot blower with a working frequency of 100~300Hz, supporting variable frequency speed regulation and intensity adjustment;

[0121] 4. Intelligent detection and control unit:

[0122] ① Detection instruments: Dust accumulation detection instrument 19 is a microwave dust accumulation detector with a detection accuracy of ±0.1mm; Moisture detection instrument 23 is an infrared moisture detector with a detection accuracy of ±0.5%;

[0123] ② Intelligent Control System: The hardware adopts an industrial control host (Intel Core i7 / 16G / 512G), an 8-channel data acquisition module (DAQ), a Profinet / Modbus communication module, a frequency converter actuator drive module, and a 15-inch human-machine interface terminal; the communication module supports Modbus RTU / TCP, Profinet, and OPCUA industrial communication protocols; the software layer is equipped with six core intelligent function modules, including an LSTM+XGBoost-based ash accumulation prediction algorithm, a fuzzy PID-based soot blowing control algorithm, and an incremental PID-based moisture control algorithm. The algorithm response delay is ≤0.5s, the control accuracy is ±2%, and the ash accumulation prediction accuracy is ≥95%.

[0124] Process Implementation

[0125] Based on the system constructed above, the desulfurization wastewater flue gas atomization drying process of the present invention is implemented, and the specific steps are as follows:

[0126] S1. Flue gas conveying and preliminary treatment: The flue gas generated by the 600MW coal-fired boiler 1 is preheated by the air preheater 2 and then enters the flue gas duct 3. The flue gas temperature rises to 320℃ and is conveyed through the flue gas duct 3 to the electrostatic precipitator 4 for dust removal treatment. The dust removal efficiency reaches 99.85%. The flue gas after dust removal enters the flue gas desulfurization treatment equipment 5 for wet desulfurization treatment. The desulfurization efficiency reaches 92%. The clean flue gas after desulfurization is conveyed through the flue gas duct 3 to the chimney 6 for emission into the air.

[0127] S2. Sludge dewatering and wastewater collection: The sludge produced by the flue gas desulfurization treatment equipment 5 is sent to the sludge dewatering equipment 7 (plate and frame filter press) for dewatering treatment. After dewatering, the moisture content of the sludge is reduced to 78%. The clear liquid produced by dewatering is used as desulfurization wastewater and is transported by the wastewater pump 8 to the wastewater conditioning and clarification equipment 10 at a flow rate of 2.1 m³ / h. The flow rate control accuracy of the wastewater is ±0.8 m³ / h.

[0128] S3. Wastewater conditioning and clarification: Polyaluminum chloride (dosage 50 mg / L) and polyacrylamide (dosage 0.5 mg / L) composite water treatment agents are added to the wastewater conditioning and clarification equipment 10 through the water treatment dosing device 11 and the water treatment agent dosing pump 12. The agitator 9 in the coagulation zone 25 mixes and flocculates the desulfurization wastewater with the water treatment agents at a speed of 300 r / min for 15 min. The mixture enters the sedimentation zone 24 and is allowed to settle for 2 h to remove 88% of the suspended solids and 65% of the soluble salts in the wastewater. After treatment, the suspended solids content of the wastewater is reduced to 96 mg / L and the total dissolved solids content is reduced to 12250 mg / L. The clear liquid in the upper layer is transported to the intermediate conditioning tank 15.

[0129] S4. Wastewater emulsification and conditioning: Polyoxyethylene ether emulsifier (dosage is 0.1‰ of wastewater volume) is added to intermediate conditioning tank 15 through emulsifier dosing device 13 and emulsifier dosing pump 14. Emulsifier mixing agitator 27 mixes the supernatant and emulsifier thoroughly for 1 hour at a speed of 200 r / min, and the mixing uniformity reaches 96%, thus obtaining emulsified wastewater.

[0130] S5. Flue gas atomization drying: Atomizing pump 16 delivers the emulsified wastewater to nozzle 18 at a pressure of 0.5MPa. Compressed air 17 at 0.7MPa mixes with the emulsified wastewater at nozzle 18. After being atomized by nozzle 18, it forms droplets with a particle size of 60~90μm, which are sprayed into flue gas 3 at a temperature of 320℃ before electrostatic precipitator 4. The atomized wastewater comes into contact with the high-temperature flue gas, and the water evaporates rapidly within 2s and is carried away with the flue gas. Salt is precipitated and suspended with fly ash in the flue gas.

[0131] S6. Enhanced water-air mixing: The mixed airflow of atomized wastewater and flue gas passes through the 45° steel baffle plate 20 and steel guide column turbulence component 21 behind the nozzle 18, the flow field is optimized, the water-air mixing rate is increased by 45%, the wastewater drying efficiency is increased to 99.2%, and the accumulation of ash and scale in the flue 3 is effectively suppressed.

[0132] S7. Intelligent Detection and Control: This step is the core of the process. The intelligent control system uses three proprietary algorithm models to achieve precise control of ash accumulation and moisture content. The specific implementation process is as follows:

[0133] ① Ash accumulation prediction and soot blowing control:

[0134] Data acquisition: At a frequency of 5 seconds, the real-time ash accumulation thickness (initial value 0.5 mm), flue gas velocity (12 m / s), flue gas temperature (320℃), and wastewater injection rate (2.1 m³ / h) of the ash accumulation detection instrument 19 were collected. After data preprocessing, the data was imported into the ash accumulation prediction algorithm based on LSTM+XGBoost.

[0135] Dust accumulation prediction: The algorithm outputs a predicted dust accumulation thickness of 2.8 mm for the next 8 hours, a dust accumulation risk value of 93.3 (high risk), and transmits the result to the dust accumulation intelligent management and control module;

[0136] Soot blowing control: The intelligent ash accumulation control module calls a soot blowing control algorithm based on fuzzy PID to calculate the current ash accumulation deviation. =3−2.8=0.2mm, deviation change rate c =0.05mm / s, and the PID coefficients are updated using fuzzy rule reasoning. The soot blowing control amount was calculated. =80, which is mapped to a soot blowing frequency of 200Hz and a soot blowing intensity of 90%, and the instruction is sent to the acoustic soot blowing device 22;

[0137] Execution feedback: The sonic soot blowing device 22 operates at 200Hz / 90% intensity. After 30 minutes, the ash accumulation thickness drops to 1.2mm. The algorithm re-predicts the ash accumulation risk value of 40 for the next 8 hours, triggering low-frequency intermittent soot blowing (50Hz / 30%) to achieve on-demand control.

[0138] ②Closed-loop regulation of water:

[0139] Data acquisition: The real-time moisture content (initial value 9.2%) of the moisture meter 23 is collected at a frequency of 5 seconds, and the deviation from the core set value of 9% is calculated. Entering the control dead zone, maintain the current flow rate of the atomizing pump at 2.1 m³ / h;

[0140] Deviation handling: Due to fluctuations in flue gas flow rate, the moisture content increased to 10.5%. =−1.5%, exceeding the control dead zone, triggering the water control algorithm based on incremental PID;

[0141] Flow regulation: Calculate the flow regulation increment based on the algorithm formula.

[0142] The output flow rate of the atomizing pump decreased from 2.1 m³ / h to 1.9 m³ / h, and the flow rate was adjusted by the frequency converter by regulating the speed of the atomizing pump.

[0143] Closed-loop feedback: 1 minute after adjustment, the moisture content dropped back to 9.3%, and the deviation was recalculated. =-0.3%, entering the control dead zone, maintain the current flow, and form a complete closed loop;

[0144] ③ Risk warning and data upload: The intelligent control system monitors dust accumulation and moisture data in real time. When the dust accumulation risk value is ≥80, a high-risk warning is issued through a pop-up window on the human-machine interface terminal and on-site audible and visual alarms. At the same time, all detection data, equipment operation data, and algorithm control data are uploaded to the power plant's SIS / MIS system via industrial Ethernet. The data upload delay is 0.8s, enabling remote monitoring.

[0145] S8. Salt solid waste treatment: Fly ash carrying precipitated salt enters the electrostatic precipitator 4 with the flue gas. After being captured and separated by the electrostatic precipitator 4, the salt capture rate reaches 98.5%. The captured fly ash is comprehensively utilized together with the power plant fly ash to achieve solid waste treatment of salt, without generating separate hazardous salt waste.

[0146] Implementation effect

[0147] This embodiment achieved the following significant results after 12 months of continuous operation at the 600MW coal-fired power plant:

[0148] The desulfurization wastewater achieves 100% zero discharge, with a daily treatment capacity of 50 m³ and an annual treatment capacity of 18,250 m³. Compared with the traditional chemical precipitation + evaporation crystallization process, it saves approximately 365,000 yuan in wastewater treatment costs annually.

[0149] No. 18 nozzles showed no obvious scaling, the desulfurizer utilization rate increased from 68% to 83%, the system resistance decreased by 62%, the induced draft fan energy consumption decreased by 18%, and the annual electricity cost was saved by about 120,000 yuan.

[0150] The ash accumulation thickness in flue 3 is stably controlled below 3mm, the ash accumulation prediction accuracy reaches 96%, the soot blowing control accuracy is ±1.5%, and no manual intervention is required for soot blowing. The boiler thermal efficiency is increased from 89% to 95.5%, saving approximately 850,000 yuan in coal costs annually.

[0151] The moisture content of the flue is stably controlled at 8%~10%, with a moisture control accuracy of ±1.8%. The corrosion rate of the equipment is reduced to 0.008mm per year. The flue and nozzles and other equipment can operate without failure for 12 months without downtime for cleaning, reducing downtime losses by about 400,000 yuan per year.

[0152] The system achieves unattended automatic operation, with each algorithm model running stably and responding quickly, reducing manual operation and maintenance costs by 75% and saving approximately 80,000 yuan in labor costs annually; all operational data is stored completely, providing accurate data support for subsequent process optimization in power plants.

[0153] In summary, the desulfurization wastewater flue gas atomization drying process and system of the present invention are highly synergistic and compatible, achieving accurate prediction of flue gas ash accumulation, on-demand control of soot blowing, and closed-loop stable control of moisture. It effectively solves the industry pain points of traditional processes, and while achieving zero discharge of desulfurization wastewater, it significantly improves the operating efficiency and intelligence level of coal-fired power plants, reduces operating costs and equipment failure rate, and has significant economic, environmental and social benefits.

[0154] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A desulfurization wastewater flue fogging drying process characterized by, Includes the following steps: S1. Flue gas transportation and preliminary treatment: The flue gas generated by the coal-fired boiler (1) is preheated by the air preheater (2) and then enters the flue (3). The flue gas is transported to the electrostatic precipitator (4) for dust removal treatment through the flue (3). The flue gas after dust removal enters the flue gas desulfurization treatment equipment (5) for desulfurization treatment. The clean flue gas after desulfurization is transported to the chimney (6) through the flue (3) and discharged into the air. S2. Sludge dewatering and wastewater collection: The sludge generated by the flue gas desulfurization treatment equipment (5) is sent to the sludge dewatering equipment (7) for dewatering treatment. The clear liquid generated by dewatering is used as desulfurization wastewater and is transported to the wastewater conditioning and clarification equipment (10) by the wastewater pump (8). S3. Wastewater conditioning and clarification: Water treatment agents are added to the wastewater conditioning and clarification equipment (10) through the water treatment dosing device (11) and the water treatment agent dosing pump (12). After the desulfurization wastewater and the water treatment agent are mixed and flocculated, the mixture is allowed to settle and remove most of the suspended solids and soluble salts in the wastewater. The clear liquid is then transported to the intermediate conditioning tank (15). S4. Wastewater emulsification and conditioning: Emulsifier is added to the intermediate conditioning tank (15) through the emulsifier dosing device (13) and the emulsifier dosing pump (14). The emulsifier is fully mixed with the supernatant to obtain emulsified wastewater, which inhibits scaling of subsequent nozzles (18). S5, Flue gas atomization drying: The atomizing pump (16) delivers the emulsified wastewater to the nozzle (18). Compressed air (17) mixes with the emulsified wastewater at the nozzle (18), and after atomization by the nozzle (18), it is sprayed into the flue gas (3) before the electrostatic precipitator (4). The atomized wastewater comes into contact with the high-temperature flue gas, the water evaporates quickly and is carried away with the flue gas, and the salt is separated and suspended with the fly ash in the flue gas. S6, Water-air mixing enhancement: The mixed airflow of atomized wastewater and flue gas passes through the baffle (20) and baffle (21) behind the nozzle (18), the flow field is optimized, the water-air mixing rate is accelerated, the wastewater drying efficiency is improved, and the accumulation of ash and scale in the flue (3) is suppressed. S7. Intelligent detection and control: The ash accumulation detection instrument (19) detects the ash accumulation content of the flue (3) and the baffle (20) in real time and transmits the data to the intelligent control system. The intelligent control system adjusts the operating frequency and intensity of the sonic soot blowing device (22) according to the ash accumulation data to remove the ash in time. The moisture detection instrument (23) detects the moisture content of the flue gas in the flue (3) in real time. The intelligent control system adjusts the delivery volume of the atomizing pump (16) according to the moisture data to control the injection volume of desulfurization wastewater. S8. Salt solid waste treatment: Fly ash carrying precipitated salt enters the electrostatic precipitator (4) with the flue gas. The electrostatic precipitator (4) collects and separates the salt, thus realizing the solid waste treatment of salt and avoiding the generation of separate salt hazardous waste.

2. The desulfurization wastewater flue gas atomization drying process of claim 1, wherein, In step S3, the desulfurization wastewater and water treatment agent are mixed and flocculated in the coagulation zone (25) of the wastewater conditioning and clarification equipment (10) by the agitator (9) for 10-20 minutes, and then enter the sedimentation zone (24) with a bottom cone shape for settling for 1.5-2.5 hours to remove more than 85% of suspended solids and more than 60% of soluble salts from the wastewater.

3. The desulfurization wastewater flue gas atomization drying process according to claim 1, characterized in that, In step S4, the supernatant and emulsifier are mixed in the mixing zone of the intermediate conditioning tank (15) by an emulsifier mixing agitator (27) for 0.5~1.5h, and the mixing uniformity reaches more than 95%; the emulsifier is a polyoxyethylene ether emulsifier, and the dosage is 0.08‰~0.12‰ of the wastewater volume.

4. The desulfurization wastewater flue gas atomization drying process according to claim 1, characterized in that, In step S5, the nozzle (18) atomizes the emulsified wastewater into droplets with a particle size of 50~100μm. The atomized droplets are adapted to the flue gas flow rate of 10~15m / s in the flue (3). The atomized wastewater comes into contact with the high temperature flue gas of 280~350℃, and the water evaporates rapidly within 1~3s.

5. The desulfurization wastewater flue gas atomization drying process according to claim 1, characterized in that, In step S6, after being reinforced by the baffle (20) and the baffle component (21), the water-air mixing rate is increased by more than 40%, and the wastewater drying efficiency is increased to more than 99%; the baffle (20) is a steel folding plate with a folding angle of 40°~50°.

6. The desulfurization wastewater flue gas atomization drying process according to claim 1, characterized in that, In step S7, the detection accuracy of the ash accumulation detection instrument (19) is ±0.1mm, and the intelligent control system controls the ash accumulation thickness of the flue (3) and the baffle (20) to below 3mm; the detection accuracy of the moisture detection instrument (23) is ±0.5%, and the intelligent control system stably controls the moisture content of the flue gas in the flue (3) to 8%~10%.

7. The desulfurization wastewater flue gas atomization drying process according to claim 1, characterized in that, In step S7, the intelligent control system is equipped with a multi-dimensional intelligent function module and has a built-in exclusive algorithm model, with a dust accumulation prediction accuracy of ≥95%. The intelligent control system performs intelligent early warning of dust accumulation risk based on the algorithm model. When the dust accumulation risk value exceeds the set threshold, it automatically triggers the acoustic soot blowing device (22) and issues multi-level warning signals. At the same time, the intelligent control system uploads the detection data and equipment operation data to the SIS / MIS system through the industrial Ethernet, with a data upload delay of ≤1s.

8. A desulfurization wastewater flue gas atomization drying system for implementing the desulfurization wastewater flue gas atomization drying process according to any one of claims 1-7, characterized in that, It includes a flue gas treatment unit, a wastewater treatment unit, a direct flue gas injection unit, and an intelligent detection and control unit; The flue gas treatment unit includes a coal-fired boiler (1), an air preheater (2), a flue (3), an electrostatic precipitator (4), a flue gas desulfurization treatment device (5), a chimney (6), and a sludge dewatering device (7). The coal-fired boiler (1), air preheater (2), electrostatic precipitator (4), flue gas desulfurization treatment device (5), and chimney (6) are connected in sequence through the flue (3). The sludge dewatering device (7) is connected to the flue gas desulfurization treatment device (5) and is used to dewater the sludge generated by the flue gas desulfurization treatment device (5). The wastewater treatment unit includes a wastewater pump (8), a wastewater conditioning and clarification equipment (10), a water treatment dosing device (11), a water treatment agent dosing pump (12), an intermediate conditioning tank (15), an emulsifier dosing device (13), and an emulsifier dosing pump (14). The wastewater pump (8) is connected to a sludge dewatering equipment (7) and a wastewater conditioning and clarification equipment (10) at both ends, respectively. The water treatment dosing device (11) is connected to the wastewater conditioning and clarification equipment (10) through the water treatment agent dosing pump (12). The wastewater conditioning and clarification equipment (10) is connected to the intermediate conditioning tank (15). The emulsifier dosing device (13) is connected to the intermediate conditioning tank (15) through the emulsifier dosing pump (14). The direct injection unit of the flue includes an atomizing pump (16), compressed air (17), nozzle (18), baffle (20) and baffle component (21). The atomizing pump (16) is connected to the intermediate conditioning water tank (15) and the nozzle (18) at both ends respectively. The nozzle (18) is located in the flue (3) in front of the electrostatic precipitator (4). The compressed air (17) is connected to the nozzle (18). The baffle (20) and baffle component (21) are arranged in the flue (3) behind the nozzle (18). The baffle (20) is a steel folding plate. The intelligent detection and control unit includes an ash accumulation detection instrument (19), a moisture detection instrument (23), an acoustic soot blowing device (22), and an intelligent control system. The ash accumulation detection instrument (19) and the moisture detection instrument (23) are both located in the flue (3). The acoustic soot blowing device (22) corresponds to the flue (3). The ash accumulation detection instrument (19), the moisture detection instrument (23), and the acoustic soot blowing device (22) are all electrically connected to the intelligent control system. The intelligent control system is equipped with a multi-dimensional intelligent function module and has a built-in exclusive algorithm model to realize intelligent perception, precise control, risk warning, and data management of the entire process.

9. The desulfurization wastewater flue gas atomization drying system according to claim 8, characterized in that, The wastewater conditioning and clarification equipment (10) includes a coagulation zone (25) and a sedimentation zone (24) that are interconnected. The coagulation zone (25) is equipped with a stirrer (9), and the sedimentation zone (24) is a clarification tank with a cone-shaped bottom. The intermediate conditioning water tank (15) is equipped with a mixing zone, and the mixing zone is equipped with an emulsifier mixing stirrer (27).

10. The desulfurization wastewater flue gas atomizing drying system according to claim 8, characterized in that, The water treatment dosing device (11) is used to dilute and mix water treatment agents, and the emulsifier dosing device (13) is used to dilute and mix emulsifiers. The dosing accuracy of agents and emulsifiers can reach ±0.5‰. The atomizing pump (16) is a high-pressure plunger pump with a rated pressure ≥0.5MPa. The nozzle (18) is a dual-fluid atomizing nozzle. The sonic soot blowing device (22) is a low-frequency sonic soot blower with a working frequency of 100~300Hz. The intelligent control system is electrically connected to the wastewater pump (8), the water treatment agent dosing pump (12), the emulsifier dosing pump (14), and the atomizing pump (16) to realize intelligent linkage control of the entire process equipment.

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