What are the functions of electric power desulfurization and denitrification equipment?

1.What is power desulfurization and denitrification equipment?
(1) Working principle of electric power desulfurization and denitrification equipment
Electric power desulfurization and denitrification equipment is the core device of the flue gas purification system of coal-fired power plants. It achieves efficient removal of sulfur dioxide (SO₂) and nitrogen oxides (NOx) through physical and chemical methods. Its working principle can be divided into two subsystems: desulfurization and denitrification.

In the desulfurization system, the most widely used is limestone-gypsum wet desulfurization technology. This technology adopts a gas-liquid reaction mechanism. After the flue gas enters the absorption tower, it contacts the sprayed limestone slurry in countercurrent. SO₂ first dissolves in water to form sulfurous acid (H₂SO₃), then reacts with calcium carbonate (CaCO₃) in the slurry to form calcium sulfite (CaSO₃), which is then forced to oxidize to form the final product, calcium sulfate dihydrate (CaSO₄·2H₂O), namely gypsum. The main chemical reactions include: SO₂ + H₂O → H₂SO₃; H₂SO₃ + CaCO₃ → CaSO₃ + CO₂ + H₂O; and 2CaSO₃ + O₂ → 2CaSO₄. This process requires strict control of the slurry pH between 5.0-5.5, a liquid-to-gas ratio of 12-18 L/m³, and a flue gas flow rate of 3-4 m/s within the absorber to achieve a desulfurization efficiency exceeding 95%.

Denitrification systems primarily utilize selective catalytic reduction (SCR) technology. Over the action of a catalyst (typically a V₂O₅-WO₃/TiO₂ system), the injected reducing agent ammonia (NH₃) undergoes a redox reaction with NOx in the flue gas, converting it into harmless nitrogen (N₂) and water (H₂O). The main reaction equations are: 4NO₂ + 4NH₃ + O₂ → 4N₂ + 6H₂O; 2NO₂ + 4NH₃ + O₂ → 3N₂ + 6H₂O. Key operating parameters of the SCR system include reaction temperature (300-420°C), ammonia-nitrogen molar ratio (0.8-1.0), and space velocity (2000-4000 h⁻¹). The catalyst is typically arranged in 2+1 layers (two operating layers + one backup layer), with each layer approximately 0.8-1.2 m thick and a design life of approximately 24,000-30,000 hours.

When the two systems operate in tandem, a "denitrification first, desulfurization second" arrangement is typically adopted. Flue gas first passes through the SCR reactor to remove NOx before entering the absorption tower to remove SO₂. This arrangement can avoid the poisoning effect of SO₂ on the denitrification catalyst, and the desulfurization tower can also synergistically remove some of the escaped ammonia and fine particulate matter. The system is also equipped with auxiliary equipment such as a pre-dust collector (removes more than 80% of fly ash), a GGH heat exchanger (recovers flue gas waste heat), and a wet electrostatic precipitator (further purification), which together form a complete flue gas purification system.

(2) Advantages and characteristics of power desulfurization and denitrification equipment
Modern power desulfurization and denitrification equipment has many technical advantages, making it the preferred solution for pollutant control in coal-fired power plants.

In terms of emission performance, the third-generation technology can achieve ultra-low emission standards: SO₂ emission concentration ≤35mg/m³ (standard state, dry basis, 6% O₂), NOx emission concentration ≤50mg/m³, and dust emission concentration ≤10mg/m³. The measured data of a 1000MW ultra-supercritical unit showed that SO₂ emissions were 28.6mg/m³ and NOx emissions were 41.3mg/m³, both exceeding the most stringent national standards. This high removal efficiency is primarily due to innovative designs such as swirl coupling technology, a high-efficiency mist eliminator, and a multi-layer catalyst.

Energy conservation and consumption reduction are another major advantage. By utilizing low-resistance tower internals, the system's total pressure drop can be controlled to ≤2500 Pa, a 600-800 Pa reduction compared to traditional designs. The variable-frequency-controlled slurry circulation pump automatically adjusts its speed based on load changes, resulting in energy savings of 25-30%. The high-efficiency mist eliminator controls flue gas moisture content to ≤75 mg/m³, significantly reducing water consumption and subsequent treatment burdens. The waste heat recovery system can generate 5-8 t/h of saturated steam at 0.8 MPa for plant heating or power generation.

A significant breakthrough has been achieved in resource utilization. The purity of the desulfurization byproduct gypsum can reach over 90%. After dehydration, it can be used as a building material, effectively transforming waste into valuable resources. The recovery rate of valuable metals (such as vanadium and tungsten) in spent catalysts exceeds 95%, and the titanium-based support can also be recycled. A 600MW unit produces about 120,000 tons of gypsum annually, creating economic benefits of nearly 10 million yuan. The application of intelligent operation and maintenance systems has improved management levels. Digital twin technology builds a virtual power plant, simulates the operating status of equipment in real time, and can predict the risk of absorber scaling 72 hours in advance. The neural network-based ammonia injection optimization system can dynamically adjust the ammonia injection amount according to CEMS data to control ammonia escape to ≤2.5mg/m³. The error of the catalyst life prediction model does not exceed ±5%, providing a scientific basis for replacement decisions. 

(3) Working areas of power desulfurization and denitrification equipment Power desulfurization and denitrification equipment is mainly used in coal-fired power plants, but with technological advancements, its application areas are constantly expanding. In the traditional power industry, large units above 300MW mostly use the desulfurization process of empty tower spray + ridge-type demister, and the denitrification system is equipped with 2+1 layers of catalyst. For 1000MW ultra-supercritical units, it is necessary to adopt a dual-tower dual-circulation desulfurization system and add steam heaters (GGH) and other strengthening measures. A 1000MW unit in my country, after adopting this configuration, has reduced annual SO₂ emissions by 80,000 tons and NOx by 35,000 tons.

Power plants burning high-sulfur coal (sulfur content >3%) require special design. These projects typically strengthen the oxidation system to maintain an oxidation-reduction potential (ORP) ≥ 200mV and utilize corrosion-resistant materials such as 2205 duplex stainless steel. During low-load operation, a catalyst low-temperature protection system is required to ensure the reaction temperature is > 280°C. A variable load control strategy (±5% load/min) is also implemented to prevent frequent system starts and stops.

In the non-power sector, flue gas treatment from steel sintering plants has become a new battleground. For highly polluted flue gases with SO₂ concentrations ≤ 5000mg/m³, integrated activated carbon desulfurization and denitrification technology has been developed to achieve coordinated control of multiple pollutants. Glass kilns utilize high-temperature SCR technology (400-450°C) and a special catalyst resistant to alkali metal poisoning to address the high-temperature challenges of traditional processes.

Typical cases include a power plant renovation project in Jiangsu. After adopting the cyclone plate tower + turbulator technology, the desulfurization efficiency increased from 97.2% to 99.3%, and the annual SO₂ emission was reduced by 23,000 tons. The project in the high-altitude cold region of Inner Mongolia installed a heating system, successfully solving the problem of slurry crystallization in winter and ensuring the stable operation of the equipment in an environment of -30℃. These practices have verified the adaptability of the technology in different scenarios. 

(4)Precautions for power desulfurization and denitrification equipment 
The operation and maintenance of power desulfurization and denitrification equipment need to focus on the following aspects: Anti-corrosion management is the top priority of the desulfurization system. Glass flake linings need to be regularly tested for sparks (≥2kV) and defects should be repaired in time. The chloride ion concentration in the slurry should be controlled at ≤20,000 mg/L. Too high a concentration will accelerate the corrosion of the equipment. Key parts using corrosion-resistant materials such as duplex stainless steel and nickel-based alloys should be regularly measured for thickness, and the annual corrosion rate should be controlled at ≤0.3mm. Anti-scaling measures directly affect the stability of the system. Organic phosphate scale inhibitors should be added to inhibit the deposition of CaSO₄·2H₂O and CaCO₃. The absorber's inner walls and spray layer should be thoroughly flushed quarterly with high-pressure water (>15 MPa). Monitor slurry density (1080-1120 kg/m³) and oxidation air volume (0.8-1.2 Nm³/kgCaSO₃) to prevent scaling risks caused by parameter deviations.

Catalyst management is the core of the denitrification system. Catalyst activity should be tested quarterly (K value drop ≤ 15%). Regeneration or replacement should be considered when activity loss exceeds 30%. A complete catalyst lifespan record should be established, recording operating hours, temperature history, and poisoning events. Ammonia spray grids should be cleaned monthly to ensure uniform ammonia distribution.

Safety protection must be constantly enforced. Ammonia areas should be equipped with a dual-detector leak alarm system (≥20 ppm, linked together), and the spray system response time should be ≤30 seconds. Before working in confined spaces, oxygen levels (>19.5%) and toxic gases (SO₂ ≤10 ppm) must be tested, and two-person supervision must be implemented. During maintenance, relevant systems must be isolated and locked out (LOTO).

Energy efficiency optimization requires meticulous management. Demister flushing valves must be tested for leaks every 5,000 cycles, and the mechanical seals of slurry circulation pumps must be replaced after 12,000 hours of operation. Equipment health records should be established, and trend analysis of key parameters should be conducted to proactively identify potential failures. Online instruments should be calibrated regularly to ensure the accuracy of CEMS data.

Personnel training is essential. Operators must master the use of diagnostic tools such as infrared thermal imagers and vibration analyzers, and technicians must possess fault tree analysis (FTA) capabilities. Professional training of at least 16 hours should be provided annually, covering new processes, new materials, and intelligent operation and maintenance. Specialized workers (such as those operating in the ammonia area) must hold certifications, which must be reviewed every two years.

The systematic implementation of these measures will ensure the long-term stable operation of desulfurization and denitrification equipment. A power plant's experience shows that strict implementation of this maintenance standard has increased equipment availability from 92% to 98%, reduced unplanned downtime by 70%, and lowered annual maintenance costs by over 25%. This fully demonstrates the importance of scientific operation and maintenance.

2.Common faults of power desulfurization and denitrification equipment
(1) Typical faults and treatment of desulfurization system
Absorber slurry foaming overflow is a common fault in wet desulfurization, which is manifested by abnormal fluctuations in the absorber liquid level and a foam layer thickness of more than 1 meter. In severe cases, it causes slurry to overflow from the demister. This phenomenon is usually caused by the following reasons: excessive organic matter content in the coal (such as petroleum coke blending), detergent components in the process water, excessive air supply from the oxidation fan, etc. A power plant once used process water containing anionic surfactants, which caused foam overflow for three consecutive days. The problem was eventually solved by adding defoaming agents (organic silicones, dosage 0.5-1.0ppm) and adjusting the coal quality.

Demister blockage will significantly increase the system pressure drop. When the pressure difference exceeds 300Pa, it is necessary to be vigilant. The blockage is mainly a mixture of gypsum crystals (CaSO₄·2H₂O) and smoke, forming a dense scaling layer on the demister blades. During treatment, the unit must be shut down for high-pressure water flushing (pressure ≥15 MPa) and the flushing water quality must be checked (suspended solids ≤50 mg/L). Preventive measures include controlling the absorber slurry supersaturation (1.0-1.2), optimizing the demister flushing procedure (30 seconds every two hours), and regularly testing the demister pressure differential.

Slurry circulation pump cavitation manifests as increased pump vibration (≥7.1 mm/s), accompanied by abnormal noise and performance degradation. This condition primarily occurs during low-load operation, when improper liquid level control leads to vortex formation at the pump suction inlet. A 600 MW unit experienced severe impeller cavitation damage at 40% load, which was completely resolved by installing anti-vortex plates and optimizing the liquid level control logic (maintaining a liquid level of ≥2.5 m). The pump's current-flow characteristic curve should be monitored regularly, and any deviations of more than 10% from the design value should be investigated immediately.

Difficulty in gypsum dehydration can result in excessive byproduct moisture content (>10%), impacting commercial value. Common causes include: insufficient slurry oxidation (ORP < 200mV), high impurity content (such as fly ash, Cl⁻), vacuum belt conveyor failure, etc. During treatment, it is necessary to detect the gypsum crystal morphology (the aspect ratio is preferably > 10:1 under electron microscopy), adjust the cyclone pressure (0.12-0.15MPa), and check the permeability of the filter cloth (≤ 50m³/m²/h). In one case, when the Cl⁻ concentration in the slurry exceeded 20,000mg/L, the gypsum moisture content increased sharply from 8% to 15%, which was improved by strengthening wastewater treatment.

(2) Typical faults and treatment methods of denitrification system
Catalyst blockage is the most frequent fault in SCR system, which is manifested as increased reactor pressure difference and increased ammonia slip. Due to the burning of high-sodium coal (Na₂O> 1.5%) in a power plant, the catalyst porosity decreased by 40% after 8,000 hours of operation. Treatment measures include: shutdown purging (0.6MPa compressed air), chemical cleaning (dilute acid immersion), and partial replacement of catalyst modules. Key prevention strategies include controlling fly ash particle size (<20μm, ≤5%), optimizing sonic sootblower frequency (operating for 30 seconds every 10 minutes), and ensuring a pre-dust removal efficiency of ≥99.5%.

Uneven ammonia injection systems can lead to fluctuations in NOx removal efficiency (±15%) and localized ammonia slip. This manifests as flow deviations of >20% across the AIG (ammonia injection grid) branches, typically caused by nozzle blockage, dust accumulation, or control valve failure. CFD simulations on one project revealed flow deviation in 40% of the nozzles. After optimizing the layout, ammonia consumption decreased by 8%. Nozzle status should be checked monthly, and a dedicated cleaning needle (diameter <80% of the nozzle diameter) should be used for cleaning.

Catalyst poisoning is categorized as chemical and physical. Arsenic poisoning (As > 5 ppm) permanently reduces catalyst activity, manifesting as a K-value decay rate > 0.5%/1000 hours. Alkali metal poisoning (K+Na > 3%) forms a glassy substance on the catalyst surface. In one case, burning high-arsenic coal (As > 100 ppm) shortened the catalyst life to 12,000 hours. Switching to an arsenic-resistant formulation restored the life to 24,000 hours. Maintaining a record of incoming coal quality and strictly controlling the content of harmful elements are key preventive measures.

Air preheater blockage is a secondary issue of SCR systems, primarily caused by ammonium bisulfate (ABS) deposition. When flue gas temperatures fall below the acid dew point (typically 280-320°C), escaping ammonia reacts with SO₃ to form viscous ABS, which adheres to fly ash and clogs the air flow channel. At one power plant, an increase in air preheater resistance by 2000 Pa caused the induced draft fan to overload. Treatment solutions include: online high-pressure water flushing (70-100℃ hot water), hot air unblocking (350℃ hot air circulation), optimized ammonia injection control, etc. The air preheater differential pressure needs to be monitored daily and offline flushing should be performed regularly.

(3) Common faults of auxiliary systems
GGH heat exchange element corrosion is particularly prominent in wet flue gas desulfurization systems, manifested as increased leakage rate (>3%) and increased pressure difference (>1.2kPa). A project used Corten steel heat exchange elements, and after two years of operation, the perforation rate due to low-temperature corrosion reached 15%. Solutions include: replacing with 2205 duplex stainless steel, increasing the sealing air temperature, and increasing the soot blowing frequency (twice per shift). The design stage should consider setting up a bypass system to ensure the operation of the unit in the event of a GGH failure.

Slurry pipe wear mainly occurs at elbows and reducers, and the wear rate can reach 2-3mm/year. A power plant experienced wear and leakage at the elbows of a Φ600 slurry pipeline. The pipeline was subsequently replaced with a lined ceramic composite pipe (with an Al₂O₃ content ≥95%), extending its service life to over 10 years. Regular thickness measurements are required (replacement is required if the remaining wall thickness is less than 50%), and the slurry flow rate must be controlled.

Abnormal CEMS data can affect environmental monitoring indicators. Common faults include probe blockage (requiring weekly backflushing), SO₂ sensor drift (requiring monthly calibration), and sampling line leaks. In one case, a faulty heating cable in the sampling pipe caused condensation, resulting in a 30% underestimation of the SO₂ measurement. This was resolved by adding a backup heating cable. It is recommended to configure a redundant measurement system and use a two-out-of-three logic for critical parameters.

Wastewater system scaling primarily occurs in the triplex tank and clarifier, with the majority of scale components being CaF₂ and CaSO₄. In one system, failure to promptly remove sludge resulted in scale buildup at the bottom of the clarifier reaching 50 cm in thickness, necessitating shutdown and mechanical cleaning. Preventive measures include: controlling the pH value of wastewater, adding scale inhibitors, and optimizing the sludge discharge cycle (5 minutes of sludge discharge every 2 hours).

(4) Systematic fault handling principles
The fault classification response mechanism is crucial. Level 1 faults (such as ammonia leakage, fire) require immediate shutdown and response time of less than 15 minutes; Level 2 faults (such as slurry pump tripping) require a plan within 4 hours; Level 3 faults (such as instrument drift) are included in the regular maintenance plan. A certain group reduced unplanned downtime by 40% through this mechanism.

Root cause analysis (RCA) should use the 5Why method to go deeper layer by layer. For example, the problem of decreased desulfurization efficiency: Level 1 cause (low slurry pH) → Level 2 cause (limestone feed failure) → Level 3 cause (rotary feed valve wear) → Level 4 cause (failure to perform preventive replacement) → Level 5 cause (lack of spare parts management system). Through this analysis, the recurrence of similar faults can be avoided.

Strategic spare parts reserves need to be managed in a hierarchical manner. Category A spare parts (such as slurry circulation pump seals) are stored on-site, Category B spare parts (such as demister blades) are held in a negotiated inventory, and Category C spare parts (such as bolts and gaskets) are purchased on-demand. One power plant implemented a "3+2" spare parts model (three months' supply + two suppliers), boosting the availability of key equipment to 99.5%.

The application of intelligent diagnostic technology is becoming increasingly important. Vibration analysis systems can predict bearing failures three to six months in advance, and infrared thermal imaging cameras can detect overheating hazards at electrical connections. After deploying an AI diagnostic platform in one project, the fault warning accuracy rate reached 85%, reducing maintenance costs by 30%.

Through systematic fault management, a 1000MW unit achieved a record of 450 days of continuous operation with zero environmental parameter violations. This demonstrates that only by establishing a scientific management system can the long-term stable operation of desulfurization and denitrification equipment be ensured.

A tabular summary of common faults in desulfurization and denitrification equipment in the power industry, including fault symptoms, possible causes and treatment measures:

3.How to extend the life of power desulfurization and denitrification equipment?
(1) Material optimization and anti-corrosion technology
Material upgrade for key components
The inner wall of the absorption tower adopts a double-layer protection system: the bottom layer is a 2mm thick glass flake lining (temperature resistance 180℃/acid resistance pH0-2), and the surface layer is a 1.5mm thick silicon carbide wear-resistant coating (Mohs hardness ≥9.5)
The flow components of the slurry circulation pump are made of duplex stainless steel 2205 (PREN value ≥35), and the impeller is laser clad (WC content 12-15%)
The GGH heat exchange element is upgraded to 254SMO super austenitic stainless steel (resistant to Cl⁻ corrosion) The strength is 5 times that of 316L)
Application of advanced anti-corrosion technology
Cathodic protection system: 20-30 sets of magnesium alloy sacrificial anodes are installed at the bottom of the absorption tower (output current density 10-15mA/m²)
Electrochemical monitoring: embedded sensors monitor the corrosion potential under the lining in real time (accuracy ±5mV)
Use polymer infiltration crystallization materials to treat concrete structures (penetration depth ≥50mm)

(2) Fine control of process parameters
Slurry quality control:
Density maintained at 1080-1120kg/m³ (test every 2 hours)
C SO₂ concentration ≤ 20,000 mg/L (wastewater treatment is initiated if exceeded)
Supersaturation controlled at 1.0-1.2 (by adjusting the oxidation air volume)
Operating parameter management:
Liquid-to-gas ratio 12-15 L/m³ (automatically adjusted based on SO₂ load)
pH 5.0-5.5 (using zone control technology)
Defogger pressure differential ≤ 300 Pa (exceeding limit triggers enhanced flushing)
Denitrification system optimization
Catalyst operating window:
Temperature 320-400°C (economizer bypass activated at low temperatures)
Ammonia nitrogen molar ratio 0.8-1.0 ( Adopt matrix ammonia injection control)
Air velocity 2000-3500h⁻¹ (dynamic adjustment when load changes)
Anti-blocking management:
Acoustic soot blower works for 30 seconds every 10 minutes (frequency 80-120Hz)
Check the catalyst module permeability every month (pressure difference ≤ 200Pa)

(3) Strengthening operation management
Optimizing operating procedures
Start-stop control:
Cold start heating rate ≤ 50℃/h
Slurry emptying time during shutdown ≥ 48h
Load adjustment:
Load change rate ≤ 5%/min
Keep two slurry pumps running at low load

4.Maintenance points for power desulfurization and denitrification
Maintaining power desulfurization and denitrification equipment is a systematic project, requiring comprehensive management across multiple dimensions, including daily operations, regular inspections, fault prevention, and technological innovation. Monitoring the operating status of the absorber is particularly important during desulfurization system maintenance. Key parameters such as slurry density, pH, and chloride ion concentration must be tested and recorded daily. Slurry density should be controlled within the range of 1080-1120 kg/m³, which is crucial for reaction efficiency and system stability. pH should be maintained between 5.0 and 5.5; excessively high or low pH levels can affect desulfurization efficiency and byproduct quality. Chloride ion concentrations exceeding 20,000 mg/L accelerate equipment corrosion, necessitating prompt implementation of wastewater treatment procedures. Managing the demister's differential pressure is also crucial. A differential pressure exceeding 300 Pa indicates possible demister blockage, necessitating immediate intensive flushing. The flushing water pressure should be maintained between 12 and 15 MPa to ensure effective flushing.

As a core component of the desulfurization system, the slurry circulation pump requires key maintenance, including vibration monitoring, seal inspection, and impeller maintenance. Vibration at the pump bearings should be controlled below 4.5 mm/s. If exceeded, alignment should be checked to ensure deviations do not exceed 0.05 mm/m. Mechanical seal leakage should not exceed 5 drops/minute, and the temperature should be maintained below 75°C. The impeller, as a consumable part, should undergo monthly thickness measurements. If wear on one side exceeds 3 mm, it should be repaired or replaced with a weld overlay. Maintenance of gypsum dehydration systems focuses on monitoring the condition of the vacuum conveyor and cyclone. The filter cloth's air permeability should be no less than 50 m³/m²/h, and the cyclone's operating pressure should be maintained within a stable range of 0.12-0.15 MPa, with fluctuations not exceeding ±0.02 MPa.

Catalyst management is paramount in denitrification system maintenance. The catalyst's K value should be tested quarterly, with an annual decay rate of no more than 15%. To prevent catalyst clogging during daily operation, the sonic soot blower should be tested daily, maintaining a frequency between 80-120 Hz. Catalyst permeability should also be checked monthly, with attention being paid to any pressure differential exceeding 200 Pa. When catalyst activity falls below 65%, chemical cleaning should be considered, which generally restores activity to over 80%. Safety management in the ammonia area must be strictly enforced, including regular testing of the dual-probe leak alarm system (set to 20 ppm), spray system response time testing (no more than 30 seconds), and evaporator maintenance inspections (checking heat exchange tubes for fouling every six months).

Maintenance of the ammonia injection grid requires attention to flow balance and nozzle condition. Flow deviation across each branch pipe should be controlled within 5%, and the nozzles should be cleaned monthly using a dedicated needle (3 mm diameter). Response testing of the automatic control system is also crucial. During load fluctuations, the ammonia injection system's response time should not exceed 10 seconds to ensure stable denitrification efficiency. As a critical heat exchanger, the GGH requires regular online high-pressure water flushing (20 MPa, quarterly) and chemical cleaning (using a pH 2 citric acid solution, annually). The sealing system must also be inspected to ensure that the gap between the sector plates does not exceed 3 mm and the air leakage rate is controlled below 1%.

CEMS system maintenance is crucial to the accuracy of environmental data. Zero and span calibration is required daily, with zero drift within ±2% F.S. and span drift within ±5% F.S. Quarterly comparisons with reference methods are required, with errors controlled within 5%, and the cleanliness of the sampling probes must be checked. Pipeline system maintenance focuses on wear monitoring and corrosion prevention. Key elbows in slurry pipelines require monthly thickness measurements to ensure the remaining thickness of the wear-resistant lining should not be less than 50%. Coating inspection of steel structures is also crucial, ensuring adhesion is maintained above 3 MPa. In areas with cathodic protection, the potential should be controlled between -850 mV and -1100 mV.

The application of intelligent maintenance technology can significantly improve maintenance efficiency. The predictive diagnostic system uses vibration analysis and oil monitoring to provide fault warnings. A 32-category fault signature library has been established, with a vibration warning threshold set at 7.1 mm/s and an alarm threshold at 11 mm/s. Oil particle counts (≥15 μm, no more than 1,000 particles/mL) and moisture content (≤0.05%) require regular monitoring. The digital twin platform uses 3D modeling to enable thermal stress analysis and corrosion prediction. Its virtual commissioning function allows for rehearsals of repair plans, with a success rate exceeding 90%. The mobile inspection system uses PDA terminals to scan equipment QR codes, upload defect photos, and invoke standard procedures. Data is automatically archived, generating an equipment health index and triggering warning work orders.

In terms of maintenance management mechanisms, a standardized operating system and lean spare parts management are necessary. Work instructions should include video demonstrations of key processes and quality acceptance criteria. Work order management is subject to a tiered approval process, with Category A work requiring signature from the chief engineer and closed-loop verification within 48 hours. Spare parts management adopts a tiered inventory strategy, with Category A spare parts maintained at a three-month supply and Category B spare parts supplied on a just-in-time basis. A full lifecycle archive and supplier performance evaluation system are also established for critical spare parts. Regarding personnel capacity building, maintenance personnel are required to obtain professional certifications in vibration analysis (ISO CAT-II) and corrosion protection engineering (NACE CIP-1), receive technical training, and participate in troubleshooting drills.

Controlling environmental indicators is the ultimate goal of maintenance work. Emission concentrations of SO₂ (≤35mg/m³), NOx (≤50mg/m³), and dust (≤10mg/m³) must be monitored in real time. Exceeding standards must be reported within 15 minutes, and root cause analysis completed within 24 hours. By-product quality control is equally important. The moisture content of gypsum should not exceed 10%, and purity must be maintained above 90%. The COD level of treated wastewater must be controlled below 60mg/L, and heavy metal compliance must reach 100%.

5.Frequently Asked Questions (FAQ) about Power Desulfurization and Denitrification Equipment
Q1: Why should the pH of the slurry in the desulfurization tower be controlled between 5.0 and 5.5? A: This pH range balances reaction efficiency and equipment corrosion protection:
When pH > 5.5: The CaCO₃ dissolution rate decreases, resulting in reduced limestone utilization (15-20% waste).
When pH < 5.0: The SO₂ absorption rate plummets, accelerating equipment corrosion (corrosion rate increases 3-5 times). Optimal control strategy: Use zoned pH control technology to maintain differentiated pH values ​​at different heights in the absorber.

Q2: Why does SCR denitrification require a temperature window of 300-420°C? A: Temperature affects catalyst activity and side reactions:
< 280°C: NH₄HSO₄ forms, clogging the catalyst (a viscous substance).
420-450°C: Catalyst sintering and deactivation (surface area decreases > 30%).
At ideal temperatures: NOx conversion efficiency can reach over 90%, with ammonia slip < 2.5 ppm.

Q3: How can I address gypsum dehydration difficulties? Step-by-step solution:
Check slurry parameters:
Supersaturation > 1.3? → Increase oxidation (ORP > 200mV)
Cl⁻ > 20,000mg/L? → Increase wastewater discharge
Check dehydration equipment:
Filter cloth air permeability < 50m³/m²/h? → High-pressure water flushing (15MPa)
Vacuum < -0.05MPa? → Check for leaks
Add crystal modifier (polyacrylamide 0.5-1ppm)

Q4: What are the early warning signs of catalyst blockage? Progressive development characteristics:
Initial stage: Increased reactor pressure differential (>300Pa)
Mid-term: Increased ammonia slip (3→5ppm)
Late-term: Localized temperature abnormalities (temperature difference >30°C)
Emergency response: Increase sootblowing (increase frequency by 50%). If ineffective within 72 hours, shut down the plant for physical cleaning.

Q5: When should the catalyst be replaced? Comprehensive Judgment Criteria:
Activity Index: K value < 0.65 (new catalyst: 1.0)
Physical Condition: > 5% blockage or > 3mm thick dust accumulation
Economical Efficiency: Regeneration cost > 40% of new catalyst price. Recommendation: Use a "2+1" configuration with batch replacement for greater economics.

Q6: How is the demister flushing cycle determined?
Dynamic Adjustment Principle:
Normal load: 2 minutes flushing every 2 hours (pressure 12 MPa)
High-sulfur coal operation: Reduce to 1.5 minutes flushing every 1 hour
When differential pressure > 350 Pa: Immediately initiate enhanced flushing procedures. Note: Flush water must be filtered (SS < 50 mg/L).