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1.What is power desulfurization and denitrification equipment?(1) Working principle of electric power desulfurization and denitrification equipmentElectric 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 equipmentModern 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 systemAbsorber 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 systemCatalyst 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 systemsGGH 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 principlesThe 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: Symptom Possible Cause Treatment Decreased Desulfurization Efficiency 1. Insufficient Absorbent (Limestone Slurry) Concentration 1. Adjust the Absorbent Ratio 2. Clogged Spray Layer Nozzles 2. Clean or Replace the Nozzles 3. Improper pH Control 3. Calibrate the pH Meter and Adjust the Dosage 4. Flue Gas Flow Exceeds Design Value 4. Check if the Boiler Load Exceeds the Design Decreased Denitrification Efficiency 1. Decreased Catalyst Activity 1. Replace the Catalyst Layer 2. Uneven Ammonia/Urea Injection 2. Optimize the Ammonia Injection Grid (AIG) 3. Flue Gas Temperature Exceeds the Catalyst Window (300-400°C) 3. Adjust the Economizer Bypass 4. SO₂/SO₃ Poisoning 4. Enhance Flue Gas Pretreatment Excessive Vibration in the Slurry Circulation Pump 1. Impeller Wear or Corrosion 1. Replace the Wear-Resistant Impeller 2. Pump Casing Cavitation 2.Check inlet pressure to prevent idling 3. Poor Coupling Alignment 3. Recalibrate alignment 4. Loose Pipe Support 4. Reinforce pipe supports. Mist eliminator blockage 1. Excessive slurry carryover 1. Optimize absorber level control 2. Insufficient flushing water pressure 2. Increase flushing water pressure to 0.2-0.3 MPa 3.Improper flushing procedure settings 3. Adjust flushing frequency (every 2-4 hours) GGH (flue gas heat exchanger) 1.Blockage caused by ammonium bisulfate crystals 1.Increase sootblowing frequency (steam or sonic) High differential pressure 2. Sootblower failure 2. Repair sootblower 3. Seal wear and leakage 3. Replace seal assembly Excessive ammonia slip 1.Excessive ammonia injection 1.Adjust CEMS feedback control 2. Uneven flue gas distribution 2. Check guide plate condition 3. Localized catalyst failure 3.Test catalyst activity distribution Absorber overflow/foam 1.Organic contaminant accumulation 1. Add defoamer 2.Insufficient oxidation air volume 2.Increase oxidation fan output 3.Liquid level meter malfunction 3.Calibrate liquid level measurement system Equipment Corrosion and Leakage 1.Damage to the rubber lining/lining scales 1.Shut down and repair the anti-corrosion coating 2.Chloride ion concentration corrosion 2.Control slurry chloride ion concentration to <20,000 ppm 3.Low-temperature acid dew point corrosion 3. Enhance flue gas reheating 3.How to extend the life of power desulfurization and denitrification equipment?(1) Material optimization and anti-corrosion technologyMaterial upgrade for key componentsThe 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 technologyCathodic 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 parametersSlurry 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 optimizationCatalyst 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 managementOptimizing operating proceduresStart-stop control:Cold start heating rate ≤ 50℃/hSlurry emptying time during shutdown ≥ 48hLoad adjustment:Load change rate ≤ 5%/minKeep two slurry pumps running at low load 4.Maintenance points for power desulfurization and denitrificationMaintaining 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 EquipmentQ1: 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 dischargeCheck dehydration equipment:Filter cloth air permeability < 50m³/m²/h? → High-pressure water flushing (15MPa)Vacuum < -0.05MPa? → Check for leaksAdd 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 accumulationEconomical 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 hourWhen differential pressure > 350 Pa: Immediately initiate enhanced flushing procedures. Note: Flush water must be filtered (SS < 50 mg/L).

1.What is a lithium carbonate laterite nickel ore roasting kiln?In the nonferrous metal smelting and processing industry, rotary kilns are used for drying, roasting, and cooling ores, concentrates, and intermediates in both nonferrous and ferrous metallurgy for the smelting of metals such as iron, aluminum, copper, zinc, tin, nickel, tungsten, chromium, iron, and lithium. A lithium carbonate laterite nickel ore roasting kiln is a high-temperature metallurgical equipment specifically designed for extracting lithium from laterite nickel ore. Laterite nickel ore is an oxide ore containing multiple metals, including nickel, cobalt, iron, and magnesium. The lithium element is typically present in an adsorbed or isomorphous form within the mineral structure, making it difficult to directly extract using traditional methods. This roasting kiln uses a high-temperature roasting process to convert the lithium in the ore into soluble compounds, creating favorable conditions for subsequent hydrometallurgical lithium extraction. This equipment is resistant to high temperatures and corrosion, making it suitable for processing laterite nickel ore with a high magnesium-to-lithium ratio and complex composition. The equipment is also equipped with a waste heat recovery system to reduce energy consumption and achieve environmentally friendly emissions. In terms of process principle, lithium carbonate laterite nickel ore roasting primarily utilizes sulfate activation roasting. After crushing, the laterite nickel ore is mixed with additives such as sodium sulfate and limestone and roasted at a moderate temperature of 750-950°C. Within this temperature range, the lithium in the ore reacts chemically with the additives to produce water-soluble lithium sulfate. Simultaneously, valuable metals such as nickel and cobalt are converted into leachable sulfates, achieving comprehensive multi-metal recovery. This process offers the advantage of lower energy consumption compared to traditional high-temperature roasting (1050-1200°C). In terms of equipment structure, this type of roasting kiln typically adopts a rotary kiln design, with a kiln body of 3-5 meters in diameter and 40-80 meters in length, installed at an inclination angle of 2-5 degrees. The kiln is divided into three temperature zones: the preheating zone, the reaction zone, and the cooling zone. Precise temperature control ensures the reaction proceeds fully. Because the roasting process generates corrosive gases, the kiln lining utilizes acid-resistant materials such as high-alumina bricks and silicon carbide coatings to extend the equipment's service life. This technology offers three key advantages: First, a lithium extraction rate of 85-92%, significantly higher than the 50-60% achieved by conventional processes; second, it enables the comprehensive recovery of multiple valuable metals, including nickel, cobalt, and lithium, with nickel recovery rates exceeding 90% and cobalt over 80%; third, it can process laterite nickel ores with low lithium content (Li₂O₂ content above 0.6%), expanding resource utilization. This technology has been applied in laterite nickel ore-rich regions such as Indonesia and the Philippines. For example, Huayou Cobalt's wet process project in Indonesia employs this roasting process. However, this technology also presents some engineering challenges. During operation, magnesia-iron oxides in the ore easily form a ring-like crust inside the kiln, requiring shutdown for mechanical cleaning typically every three months. Furthermore, corrosive gases such as sulfur dioxide generated during roasting can corrode the refractory materials, resulting in a kiln lining lifespan of typically only 8-12 months. In addition, the energy consumption of this process is relatively high, with heat consumption of about 1000-1200kWh per ton of ore, and measures such as waste heat recovery are needed to reduce energy consumption. 2. Function of lithium carbonate laterite nickel ore roasting kiln(1) Working principle: scientific mechanism of high temperature chemical transformationThe core function of lithium carbonate laterite nickel ore roasting kiln is to achieve the selective transformation of valuable metals in ore through high temperature thermochemical process. This process is based on the dissociation of mineral crystal structure and chemical rearrangement of elements. Its scientific mechanism can be divided into three stages: Mineral dissociation stage (400-650℃)The main carrier minerals in laterite nickel ore (such as limonite and serpentine) undergo lattice fracture during heating. Limonite (FeOOH) dehydrates and transforms into hematite (Fe₂O₃), while releasing lithium ions adsorbed on the mineral surface; serpentine (Mg₃Si₂O₅(OH)₄) decomposes into forsterite (Mg₂SiO₄) and silica. The key control parameter in this stage is the heating rate, which is usually controlled at 5-8℃/min. Too fast will cause premature sintering of the outer layer of the mineral, hindering the release of internal lithium. Sulfation Reaction Stage (700-950°C)Added sodium sulfate (Na₂SO₄) decomposes at high temperatures to produce reactive SO₃ gas, which reacts with free lithium to form soluble lithium sulfate (Li₂SO₄). The activation energy for this reaction is approximately 120 kJ/mol, requiring precise control of the oxygen partial pressure in the kiln (maintaining 0.5-2 vol% O₂) to ensure the reaction proceeds in the forward direction. Metals such as nickel and cobalt also undergo similar transformations, but iron, forming a stable Fe₂O₃, largely avoids the reaction. This selective transformation is a key advantage of the process. Product Stabilization Stage (300-500°C)The material undergoes a slow cooling process in the cooling zone, allowing the newly formed sulfate to form a stable crystal structure. The cooling rate during this stage directly affects subsequent leaching performance. Experimental results show that optimal lithium sulfate leaching rates are achieved when the cooling rate is controlled at 15-20°C/min. (2) Advantages and characteristics Revolutionary improvement in resource utilization efficiency In traditional laterite nickel ore wet smelting, the lithium recovery rate is generally less than 30%, while the roasting process increases the lithium recovery rate to 85-92% by breaking and reorganizing chemical bonds. Data from a project in Indonesia shows that 12-15 kg of lithium carbonate equivalent can be extracted per ton of ore with a Li₂O content of only 0.8%. The synergistic recovery of nickel and cobalt is significant. Under typical operating conditions, the nickel recovery rate can reach 90-93% (an increase of 10-15 percentage points compared to direct high-pressure acid leaching), and the cobalt recovery rate is 82-85%. Based on a production line with an annual output of 20,000 tons of lithium carbonate, 35,000 tons of nickel sulfate and 4,000 tons of cobalt sulfate can be produced simultaneously. Energy Consumption and Cost OptimizationUsing "sodium sulfate autothermal decomposition" technology, the heat released by the decomposition of Na₂SO₄ (ΔH = -1387 kJ/kg) offsets some of the heat demand, reducing overall energy consumption per ton of ore to 850-1000 kWh, a 35-40% reduction compared to spodumene conversion roasting.Raw material adaptability offers cost advantages. Low-grade ore discarded from nickel smelters (Ni < 1.2%, Li₂O 0.6-1.2%) can be directly used, resulting in raw material procurement costs that are 60-70% lower than spodumene concentrate. Innovative Breakthroughs in Environmental Friendly EfficiencyDevelopment of a "sulfur recycling" system: SO₂ generated by roasting is recycled through catalytic oxidation to produce acid, achieving a sulfur utilization rate of over 85%, reducing sulfur purchases by 50% compared to traditional processes.Hydrogen roasting trials have shown that by replacing 30% of the fuel with green hydrogen, carbon emissions per ton of lithium carbonate can be reduced from 12 tons to 7.5 tons, a 37.5% reduction. (3) Work area: Cross-industry strategic applicationNew energy material preparationShort-process production of battery-grade lithium carbonate: A project in Indonesia uses the new "roasting-leaching-ion sieve adsorption" process, and the product purity reaches 99.95%, fully meeting the requirements of NCM811 positive electrode materials.Preparation of ternary precursors: The roasting leachate can be directly used to synthesize NCM523, eliminating the intermediate product conversion step and reducing the precursor production cost by 18-22%.Strategic resource securityThe global laterite nickel ore resources are about 13 billion tons (containing more than 50 million tons of lithium metal). Through this technology, the new lithium resource reserves can be equivalent to 35% of the current global lithium resources, significantly alleviating my country's dependence on foreign lithium resources (from 70% to 45%). Value-added utilization of metallurgical solid wasteTreatment of nickel-iron smelting slag: A factory in the Philippines roasted nickel-iron slag (containing 0.3-0.5% Li₂O) with primary ore, and the lithium recovery rate still reached 75%, with a value-added of US$120-150 per ton of slag. (4) Precautions in engineering practiceRaw material pretreatment specificationsParticle size control: The optimal crushing range is 0.5-3mm. Particles >5mm will result in unreacted cores in the center, and particles <0.2mm will increase the air flow resistance in the kiln. A three-stage crushing (jaw crusher + cone crusher + vertical mill) and airflow classification system are required.Mixed material uniformity: The deviation of the mass ratio of sodium sulfate to ore (usually 8-12%) must be <±1%. It is recommended to use a double-shaft differential speed mixer (mixing uniformity >95%). Roasting Process ControlTemperature Field Management: A three-zone control system was established, with the preheating zone at 650±20°C, the reaction zone at 880±15°C, and the cooling zone at 450±30°C. Infrared thermal imaging was used to monitor the kiln lining temperature in real time.Atmosphere Conditioning: O₂ concentrations were controlled at 1.5±0.3 vol% through online oxygen content analysis at the kiln outlet (a laser gas analyzer was recommended) to prevent excessive decomposition of sodium sulfate. Equipment Maintenance Key PointsRefractory Protection: SiC-Al₂O₃ composite bricks (230mm thickness) were used. Erosion was monitored every three months and replacement was required when the remaining thickness was less than 80mm.Ring Treatment: An intelligent ring cleaning robot was developed, equipped with a high-frequency hydraulic vibrating blade (vibration frequency 50-80Hz), capable of removing over 90% of rings without stopping the kiln. Safety and Environmental Protection MeasuresCO Protection: Dual-channel CO monitoring (electrochemical and infrared sensors) was installed at the kiln outlet. Emergency ventilation (air volume ≥ 30 m³/min) was automatically activated when the concentration exceeded 50 ppm. Dust control: Using a two-stage system of "cyclone dust removal + bag dust removal", the emission concentration can be stabilized at <15mg/m³. 3.How to extend the service life of lithium carbonate laterite nickel ore roasting kilnExtending the service life of lithium carbonate laterite nickel ore roasting kilns requires systematic optimization across multiple dimensions, including equipment design, process control, and operation and maintenance. In actual production, kiln service life is often affected by multiple factors, including refractory wear, mechanical fatigue, and fluctuations in process parameters. Therefore, a comprehensive approach is essential. When selecting refractory materials, particular attention should be paid to their resistance to sulfate attack. Because the roasting process of laterite nickel ore produces large amounts of sulfur-containing gases, traditional refractories are susceptible to chemical attack. Silicon carbide-corundum composite bricks are recommended as the primary kiln lining material. These materials offer over three times the resistance to sulfate corrosion compared to traditional high-alumina bricks at 950°C. Furthermore, differentiated lining designs should be employed for different sections of the kiln. For example, dense refractory bricks up to 300mm thick can be used in the high-temperature reaction section, while lighter insulating refractory materials can be used in the transition section. During kiln lining construction, strict control of masonry quality is crucial, with brick joints kept to within 1mm and sealed with specialized refractory mortar. Control of process parameters has a decisive impact on kiln service life. First, a stable temperature gradient must be established, creating a suitable temperature distribution of 400-950°C from the kiln tail to the kiln head. The reaction zone temperature must be strictly controlled within the range of 880±15°C. Excessively high temperatures will accelerate the deterioration of the refractory materials, while excessively low temperatures will lead to incomplete reactions. Real-time monitoring of the kiln surface and internal temperatures is achieved by installing infrared thermometers and thermocouple arrays. Controlling the oxygen content is also critical; maintaining an oxygen concentration of 1.2-1.8% ensures sufficient sulfation reaction while preventing damage to the kiln body from an excessively oxidizing atmosphere. Mechanical structure maintenance is essential. The kiln body's ovality deviation must be controlled within 0.2% of the kiln diameter and inspected monthly with a laser straightness gauge. High-temperature lithium-based grease must be used for lubrication of the supporting roller bearings, and the oil temperature must not exceed 65°C. Common kiln body deviation issues can be addressed through dynamic adjustment using a hydraulic tumbler system, maintaining axial play within a ±3mm range. The meshing clearance of the transmission gears must be regularly inspected to ensure that the contact area exceeds 60%. Raw material pretreatment is crucial for extending kiln life. The particle size of incoming materials should ideally be controlled between 0.8 and 3.0 mm. Coarse particles can cause localized overheating, while fine particles increase airflow resistance within the kiln. Harmful elements such as chlorine and fluorine in the raw materials must be strictly limited. Chlorine levels exceeding 0.05% can significantly accelerate refractory corrosion. For raw materials with high sulfur content, pre-oxidation treatment is recommended to reduce the sulfur content to below 1% before entering the kiln. Establishing an intelligent maintenance system is an inevitable trend in modern production. By installing equipment such as vibration sensors and oil analyzers, a predictive maintenance system can be constructed. When bearing vibration exceeds 4.5 mm/s or the iron content in the lubricating oil exceeds 50 ppm, the system will automatically issue an alert. The application of digital twin technology can create a virtual kiln model to simulate equipment conditions under different operating conditions, supporting maintenance decisions. The professional quality of operators is equally important. Detailed operating procedures should be established, and improper operations such as rapid cooling and heating should be strictly prohibited. Each time the kiln is shut down for maintenance, it must be slowly cooled according to standard procedures, with a cooling rate not exceeding 50°C/hour. When re-igniting, the temperature must be raised in stages to avoid thermal stress concentration that could cause cracking in the refractory material. Through the comprehensive implementation of these measures, the service life of lithium carbonate laterite nickel ore roasting kilns can be extended from the typical 12-18 months to over 30 months. A large smelting company has demonstrated that after adopting new refractory materials and an intelligent control system, its roasting kiln has maintained excellent operation for 26 months, reducing annual maintenance costs by over 40%. This demonstrates the significant effectiveness of scientific and systematic maintenance management in extending equipment life. 4.Common faults of lithium carbonate laterite nickel ore roasting kilnDuring long-term operation, lithium carbonate laterite nickel ore roasting kilns are subject to a variety of typical faults due to high temperatures, corrosive atmospheres, and complex operating conditions. These faults primarily manifest in the refractory, thermal, and mechanical systems, requiring operators to accurately identify their characteristics and address them promptly. Refractory system faults are the most common and serious. Abnormal lining erosion is the most prominent problem, manifesting as localized high-temperature areas on the kiln surface. Infrared imaging reveals temperatures exceeding 50°C above normal. In severe cases, the kiln shell may even turn red. This fault is caused by sulfate penetration and a chemical reaction with the refractory material, forming a low-melting-point eutectic phase that causes a dissolution effect at around 900°C. Treatment requires immediate reduction of the temperature in this area and monitoring of the erosion depth. When the remaining thickness is less than 80 mm, the kiln must be shut down and replaced. Abnormal kiln lining shedding is another typical fault, manifesting as sudden, increased kiln vibration with an amplitude exceeding 8 mm/s and shell temperature fluctuations exceeding 30°C within a short period of time. Small areas of shedding can be repaired with hot gunning material, while larger areas require the kiln to be shut down and replaced. Failures in the thermal system directly impact production process stability. Preheater blockage is a gradual process. Initially, the system negative pressure rises abnormally to over 6500 Pa. In the middle stage, a temperature difference exceeding 80°C may be observed in the lower cyclone, ultimately leading to complete blockage. To address this, first activate the air cannon clearing system, maintaining a pressure of 0.6-0.8 MPa and cycling the air every 15 minutes. Severe blockage requires remote clearing with a 10-15 MPa high-pressure water jet. Burner flashback is a dangerous failure. Monitoring at the kiln head reveals unstable flames with pulsating flames, accompanied by a sharp rise in CO concentration to over 500 ppm. In this case, immediately reduce the primary air volume to less than 15% of the total air volume, and check the pulverized coal fineness and carbon deposits in the nozzles. Mechanical system failures often cause sudden downtime. Overheating of the roller bearing is the most common mechanical failure. When the temperature exceeds 75°C, check the lubrication, contact, and cooling systems. Oil film thickness less than 0.02 mm, contact spot area less than 50%, or cooling water flow less than 10 cubic meters per hour can all lead to overheating. If the temperature exceeds 85°C or the vibration value exceeds 7.1 mm/s, emergency shutdown is required. A broken tooth in the ring gear is a serious mechanical failure, usually caused by excessive tooth side clearance. The standard clearance should be 2-4 mm, and exceeding 8 mm is highly likely to cause tooth breakage. On-site repair requires overlay welding with specialized welding rods and tooth profile correction using a laser tracker. Transmission system failures should also not be ignored. Pitting corrosion on reducer gears manifests as fish-scale-like pits on the tooth surface, accompanied by abnormal noise. When the pitting area exceeds 30% of the tooth surface, the gear pair must be replaced. Failure of the hydraulic retaining wheel can cause uncontrolled axial movement of the kiln body. The standard movement should be controlled within ±3 mm. If it exceeds this range, the hydraulic station pressure and position sensors should be checked. Although electrical control system failures are less common, they can have significant consequences. Temperature sensor drift can cause the displayed temperature to deviate from the actual temperature by more than 15°C. Regular on-site calibration with a standard thermocouple is necessary. Frequency converter overload often occurs during startup. In addition to checking the mechanical load, the acceleration time parameters should be optimized. For heavily loaded equipment, the startup time is recommended to be set to at least 30 seconds. In actual production, these faults are often interrelated. For example, refractory erosion can alter the temperature distribution of the kiln, thereby affecting thermal performance; mechanical vibration can exacerbate refractory damage. Therefore, it is essential to establish a comprehensive equipment health record, documenting the characteristic parameters, treatment methods, and follow-up data for each fault. By analyzing this data, patterns in fault occurrence can be identified. For example, one plant observed a significant increase in preheater scaling in the third week after each raw material supplier change. Testing later revealed this was related to the higher potassium and sodium content in the new raw materials. Preventive maintenance is key to reducing failures. A three-tiered inspection system is recommended: hourly inspections by operators, focusing on routine parameters such as temperature and pressure; daily specialized inspections by technicians, using tools such as infrared thermometers and vibration detectors; and weekly comprehensive diagnostics by a dedicated team. At the same time, we must fully utilize modern monitoring technologies. For example, installing an online vibration analysis system can predict bearing failures 3-6 months in advance. Using acoustic emission technology can detect early signs of kiln crack growth. Verifying the effectiveness of fault handling is equally important. After each repair, continuous monitoring should be conducted for 72 hours, recording the trends of key parameters. In particular, after kiln lining repairs, kiln temperature must be measured hourly during the first three shifts to ensure that temperature fluctuations in the repaired area remain within normal ranges. For drive system repairs, no-load and loaded test runs are required, and vibration values must drop below 4.5 mm/s to qualify. Through scientific fault management and preventive maintenance, unplanned downtime in lithium carbonate laterite nickel ore roasting kilns can be reduced to less than 3%, significantly improving equipment availability. A large smelting company has demonstrated that implementing systematic fault management reduced the annual number of kiln failures from 23 to 6, reduced maintenance costs by 40%, and increased production capacity by 15%. This demonstrates that only by accurately identifying fault characteristics, thoroughly analyzing the causes, and implementing targeted measures can long-term stable equipment operation be ensured. The following is a summary table of common faults in lithium carbonate laterite nickel ore roasting kilns, including fault phenomena, possible causes and treatment measures: Symptom Possible Cause Handling Measures Abnormal Kiln Temperature Fluctuation 1. Unstable Fuel Supply 1.Check Fuel System Pressure/Flow 2. Temperature Meter Failure 2.Calibrate or Replace Thermocouples 3. Ringing in the Kiln Leading to Uneven Heat Distribution 3. Stop the Kiln to Clean Rings or Adjust the Burner Angle Excessive Exhaust Temperature at Kiln Exhaust 1. Low Feed Moisture Content 1. Adjust Feed Moisture Content (5-8%) 2. Insufficient Secondary Air Volume 2. Increase Secondary Air Supply 3. Reduced Preheater Heat Exchange Efficiency 3. Clean Preheater Ash or Replace Heat Exchanger Tubes Ringing/Nodules in the Kiln 1. Excessive SiO₂/Al₂O₃ Ratio in the Feedstock 1. Control Feedstock Impurity Content (SiO₂ < 6%) 2. Localized Excessive Temperature 2. Optimize Burner Air Distribution 3. Calcination Temperature Exceeds 1250°C 3. Add flux (e.g., CaF₂) Low calcination conversion rate 1. Insufficient calcination temperature 1. Increase kiln temperature to 1050-1200°C 2. Short residence time 2. Reduce kiln speed or extend kiln length 3. Uneven raw material particle size 3. Strengthen raw material screening and pretreatment Abnormal kiln vibration 1. Damaged support roller bearing 1. Replace support roller bearing 2. Kiln body bending and deformation 2. Stop kiln and correct kiln body straightness 3. Poor gear meshing 3. Adjust gear clearance (0.25-0.3 modules) Material leakage at kiln head/tail 1. Worn seals 1. Replace graphite seals or scales 2. Large kiln pressure fluctuations 2. Adjust induced draft fan air pressure 3. Excessive feed rate 3. Control feed rate within rated capacity Refractory material shedding 1. Frequent thermal shock 1. Avoid rapid heating and cooling. 2. Poor masonry quality 2.Use phosphate-bonded refractory bricks 3. Chemical Attack 3.Regularly apply protective coatings Abnormally high motor current 1. Excessive kiln load (ringing) 1. Clean kiln material accumulation 2. Poor drive system lubrication 2. Replenish grease (lithium-based grease) 3. Unstable voltage 3. Install a voltage stabilizer Abnormal product color 1. Insufficient reducing atmosphere (Fe₃⁺ not fully reduced) 1. Adjust CO concentration (3-5%) 2. Sulfide residue 2. Extend roasting time or improve exhaust gas treatment efficiency Sudden increase in dust removal system differential pressure 1. Damaged or clogged filter bags 1. Replace filter bags (PTFE) 2. Faulty cleaning process 2. Repair pulse valve 3. High flue gas humidity causing bag sticking 3. Increase flue gas preheating (>120°C) 5.Lithium Carbonate Laterite Nickel Ore Roasting Kiln Maintenance Guide(1) Daily operation and maintenance specificationsOperation parameter monitoringRecord key data every 2 hours: kiln head temperature (controlled ±15℃), kiln tail negative pressure (-50±10Pa), main motor current (fluctuation ≤10%)Focus on the oxygen content curve, maintain the range of 1.2-1.8%, and immediately check the sealing system in case of abnormalityLubrication management standardsThe roller bearing uses high-temperature grease (dropping point > 260℃), which is replenished every 8 hoursReplace the reducer gear oil after the first 500 hours and every 3000 hours thereafter , oil quality inspection standards: kinematic viscosity change ≤ ± 10%, moisture content ≤ 0.05%, iron content ≤ 50ppmKey points of visual inspectionObserve the gap between the wheel rim and the pad when the kiln body rotates (1.5-2mm is best)Check the wear of the kiln head sealing graphite block (single-side wear > 5mm needs to be replaced)Confirm that there is no abnormal vibration of the cooling fan (amplitude ≤ 4.5mm/s) (2). Refractory material maintenance strategyKiln lining monitoring technologyUse infrared thermal imager to scan the entire kiln every week to establish a temperature distribution mapKey monitoring: • Temperature gradient in the firing zone (3D-5D area) • Condition of transition zone lining jointsImmediately arrange for thickness measurement if abnormal temperatures are detected (ΔT > 50°C)Kiln lining maintenance methodsMaintain a stable thermal system to avoid temperature fluctuations > 30°C/hourControl harmful raw material components: • Cl⁻ < 0.03% • Alkali content (K₂O + Na₂O) < 2%Monthly kiln lining strength testing (rebound value ≥ 40 MPa)Repair technical specificationsFor small areas of spalling (< 0.5 m2), perform hot gunning repairs: • Al₂O₃ content of gunning material ≥ 70% • Gunning thickness controlled within 50-80 mmExtensive damage requires the kiln to be shut down for cold repairs, strictly adhering to the following: • Cooling rate ≤ 50°C/hour • The misalignment between the new and old linings is ≤3mm. (3) Mechanical system maintenance pointsTransmission maintenanceGear ring maintenance: Monthly tooth side clearance inspection (standard 2-4mm), regular gear rotation (180° rotation every 6 months)Pulley adjustment: Bearing clearance 0.10-0.15mm, contact angle 30-45°Hydraulic system maintenanceOil cleanliness NAS Level 7, monthly inspection: particle count (>15μm particles ≤1000/mL), acid value (≤0.5mgKOH/g)Filter element replacement cycle: main circuit filter element 200 hours, pilot filter element 500 hoursDynamic seal managementKiln tail fish scale seal: gap adjustment 5-8mm, weekly replenishment of high-temperature greaseKiln head graphite block seal: replacement if wear >1/3 thickness, compression spring pressure test (50±5N) (4). Preventive maintenance planMonthly maintenance itemsClean the preheater cyclone crust (allowable thickness ≤30mm)Check the grate Wear of cooling grate (single side ≤ 3mm)Calibrate temperature sensor (error ≤ ±1.5℃)Annual overhaul contentComprehensive assessment of refractory materials: remaining thickness of fired belt lining ≥ 100mm, no through cracks in transition zoneMechanical system inspection: kiln body straightness ≤ 0.2‰L, wheel ellipticity ≤ 0.15%DReplacement cycle of key componentsKiln head burner nozzle: 8000 hoursHigh temperature fan impeller: 24000 hoursHydraulic cylinder seal: 12000 hours (5). Application of intelligent maintenance technologyOnline monitoring systemInstallation of vibration monitoring terminal: Sampling frequency 10kHz, warning value 7.1mm/s, alarm value 11mm/sLubricating oil online sensor: real-time monitoring of moisture content, metal abrasive alarm (Fe＞50ppm)Predictive maintenance platformEstablish equipment health records: accumulated operating data, maintenance record traceability, life prediction modelImplement remaining life assessment (error ≤±5%)Digital twin systemKey parameters of 3D modeling: thermal stress distribution, mechanical load simulation, wear trend predictionVirtual commissioning maintenance plan (success rate＞90%) (6). Safety and emergency managementHazardous working conditions Action: CO concentration exceeds the standard (>30 ppm): Initiate emergency ventilation (air volume ≥30 m³/min), evacuate personnel immediately.Maintenance Safety Regulations:Confined Space Operations: Oxygen content monitoring (19.5-23%), continuous ventilation (≥20 m³/min), two-person supervision.High-Temperature Equipment Operations: Thermal insulation clothing must withstand temperatures ≥800°C and must be cooled to below 60°C before contact.Emergency Spare Parts Reserve:Class A Critical Spare Parts (on-site storage): Kiln head seal assembly (2 sets), hydraulic valve assembly (1 set), temperature sensors (10 units).Class B Conventional Spare Parts (agreed inventory): Refractory bricks (5-day supply), transmission gears (1 set). 6.FAQs about lithium carbonate laterite nickel ore roasting kiln（1）. What is the optimal operating temperature range for a roasting kiln?The optimal working temperature of the roasting kiln is usually controlled between 1050-1200℃. Too low the temperature will lead to incomplete metal conversion, while too high may cause rings in the kiln and energy waste. The specific temperature setting needs to be adjusted according to the raw material composition. Generally, nickel ore roasting is controlled at around 1100℃, and lithium ore roasting can be slightly lower than 1050℃. （2）. How to judge whether there is a ring phenomenon in the kiln?The following signs are mainly observed: Abnormal fluctuations in kiln body temperatureUnstable motor currentProduct conversion rates suddenly droppedLocal overheating and redness on the appearance of the kiln body can be monitored in real time by regularly scanning the kiln surface with an infrared camera, or installing an in-kiln camera. （3）. What is the influence of raw material particle size on roasting effect?The ideal raw material particle size should be controlled within 30-50mm:Too large particle size: low heat transfer efficiency, prone to incomplete center burningToo small particle size: It affects ventilation in the kiln and increases the amount of dust. It is recommended to use a multi-stage crushing and screening system to ensure particle size uniformity. （4）. How to choose the right refractory material?The following factors should be considered:High temperature resistance: Must withstand instantaneous high temperatures above 1300℃Corrosion resistance: Resistance to fluoride and sulfide attackThermal shock stability: It is recommended to use high-aluminum (Al ˇ O ≥70%) or magnesium-aluminum spinel refractory bricks to adapt to frequent start-ups and stops. （5）. What are the common waste gas treatment methods?The main treatment processes include:Dry treatment: bag dust removal + activated carbon adsorptionSemi-dry method: spray drying + bag dust removalWet treatment: When selecting alkali washing towers, exhaust gas composition (SOx, fluoride, etc.) and emission standard requirements need to be considered. （6）. How to improve metal recovery?The following measures can be taken:Optimize ore matching ratioAccurately control the amount of reducing agentExtend material retention timeUsing segmented temperature control technology recommends regular process calibration to find out the best operating parameters. （7）. What key points need to be paid attention to in daily maintenance?Key maintenance projects include:Weekly inspection of transmission lubricationMeasure the straightness of the kiln body every monthRefractory inspection quarterlyIt is very important to comprehensively overhaul the power system every year and establish a sound point inspection system and equipment files. （8）. How to reduce energy consumption?Energy-saving measures include:Install waste heat boiler to recover heat from exhaust gasAdopt frequency conversion control fanOptimize insulation thicknessImplementing an energy management system can typically reduce energy consumption by 15-25%. （9）. How to deal with an emergency kiln shutdown?Standard emergency procedures:Cut off fuel supplies immediatelyActivate backup power supply and maintain slow runningLower the temperature according to procedures (≤50℃/h)Record various parameters for future reference and conduct emergency drills regularly in peacetime. （10）. How to judge the quality of roasted products?Main test indicators:Nickel/cobalt/lithium conversionAcid dissolution rateimpurity contentIt is recommended to establish a complete quality testing system for physical characteristics (particle size, color, etc.), including online monitoring and laboratory analysis.

1. What is active limeActive lime (also known as quicklime or calcium oxide, chemical formula CaO) is a lime product with high reactivity. Due to its special physical and chemical properties, it is widely used in many fields such as industry, environmental protection, and construction. The following are its main characteristics and functions: (1) Characteristics of active limeHigh chemical activityIt is made by calcining high-quality limestone, with a high CaO content (usually ≥90%) and few impurities. It can react quickly with water, acid, etc.It reacts faster and more efficiently than ordinary lime. Porous and loose structureCO₂is released during the calcination process, forming a porous structure with a large specific surface area and strong adsorption and reaction capacity. Low impurity contentThe content of harmful impurities such as sulfur and phosphorus is low, suitable for fields with high purity requirements (such as metallurgy and chemical industry). Strong alkalinityThe aqueous solution is strongly alkaline (pH ≥ 12.5) and can neutralize acidic substances. Strong hygroscopicityIt easily absorbs moisture and CO₂ in the air and needs to be stored in a sealed manner. (2) The main role of active limeMetallurgical industrySteelmaking: as a slag-making agent, removes impurities such as sulfur and phosphorus, and improves the purity of molten steel.Hot metal pretreatment: desulfurization (reacts with sulfur to form CaS), reducing subsequent smelting costs. Environmental protectionWastewater treatment: neutralizes acidic wastewater and precipitates heavy metals (such as generating Ca₃(PO₄)₂ to remove phosphorus).Flue gas desulfurization (FGD): reacts with SO₂ to form gypsum (CaSO₄), reducing acid rain pollution.Waste incineration: adsorbs harmful gases such as dioxins, reducing pollution emissions. Chemical industryProduction of calcium carbide: reacts with coke to produce acetylene (CaO + 3C → CaC₂ + CO).Preparation of calcium carbonate: reacts with CO₂ to form precipitated calcium carbonate (CaCO₃), which is used for fillers, coatings, etc. Construction and building materialsProduction of aerated concrete: reacts with siliceous materials to form cementitious substances (hydrated calcium silicate).Soil solidification: improves acidic soil and improves foundation stability. Other applicationsMedicine/food: used as a desiccant or disinfectant (food grade purity required).Agriculture: regulates soil pH, supplements calcium, and promotes crop growth.Papermaking: used in alkali recovery processes and treats pulp black liquor. (3) PrecautionsStorage: must be moisture-proof and sealed to avoid contact with water and acid (exothermic reaction may cause danger).Safety: wear protective equipment during operation to prevent dust inhalation or skin contact (highly corrosive). 2.Main process flow of an active lime production lineActive lime (quicklime, CaO) is produced by the pyrolysis of limestone (CaCO₃). The core process includes raw material pretreatment, calcination, cooling, and finished product processing. Limestone is stored in silos and lifted by an elevator to the top bin of the preheater. Two level gauges control the level in the top bin, and the limestone is evenly distributed to each preheater chamber through a discharge pipe. In the preheater, the limestone is heated to approximately 900°C, decomposing approximately 30% of the limestone. Hydraulic push rods push the limestone into the rotary kiln. The limestone sintered in the rotary kiln, decomposing it into CaO and CO₂. The decomposed limestone enters the cooler, where it is cooled by cold air blown into the cooler to below 100°C before being discharged. After heat exchange, the 600°C hot air enters the kiln and mixes with the coal gas for combustion. The exhaust gas mixes with the cold air and is passed through an induced draft fan to a bag filter, and then through an exhaust fan to the chimney. The lime from the cooler is transported to the finished lime storage bin via a vibrating feeder, chain bucket conveyor, bucket elevator, and belt conveyor. The following is a typical process flow and key equipment description of an active lime production line: (1) Main process flow of an active lime production line1)Raw material pretreatmentLimestone crushing and screeningLarge limestone (≤1m) is crushed and medium-crushed to 30~50mm particles by jaw crushers, impact crushers, etc.Screening through a vibrating screen removes dirt and impurities to ensure uniform particle size (too small affects air permeability, and too large calcination is not transparent).Raw material storageQualified limestone is sent to the raw material warehouse to avoid mixing with impurities (such as SiO₂, Al₂O₃, etc. that affect lime activity). 2)Calcination Process (Core Step)Preheating Stage (100-900°C)Limestone is preheated in a preheater using kiln exhaust gas to remove surface moisture and some volatile matter, improving thermal efficiency.Pyrolysis (900-1200°C)Limestone is calcined in a rotary kiln or shaft kiln, undergoing the decomposition reaction: CaCO₃ → CaO + CO₂↑ (endothermic reaction).Key Control Parameters:Temperature: Rotary kilns typically operate at 1050-1250°C, shaft kilns at 900-1100°C.Retention Time: Rotary kilns typically operate at approximately 1-3 hours, shaft kilns at approximately 6-12 hours.Fuel: Natural gas, pulverized coal, coke oven gas, etc. (Low-sulfur fuels are preferred to avoid sulfur contamination). 3)Cooling and Waste Gas TreatmentLime CoolingHigh-temperature lime (approximately 200-300°C) is cooled to below 80°C via a vertical cooler or air cooling system to prevent secondary carbonization (CaO + CO₂ → CaCO₃).The recovered hot air can be fed into the calcination system for recycling.Waste Gas TreatmentAfter cyclone and bag filter dust removal, the kiln exhaust gas is partially recovered for use in the chemical or food industries, with the remainder discharged in compliance with emission standards. 4)Finished Product ProcessingCrushing and ClassificationThe cooled lime blocks are crushed to 1-10mm (particle size adjusted based on application) using a double-roll crusher or hammer crusher.Vibrillation screening is used to select different product specifications (e.g., coarse granules for steelmaking, fine powder for environmental protection).Storage and PackagingFinished products are stored in sealed warehouses to prevent moisture and carbonization.Some products can be briquetted or packaged in bags (special packaging is required for food-grade lime). (2).Key equipment selectionProcess Common equipment Function and featuresRaw material crushing Jaw crusher, impact crusher Coarse to medium crushing, processing large limestone lumpsCalcination kiln Rotary kiln, double-chamber shaft kiln, beam shaft kiln Rotary kiln has high output (over 1,000 tons/day), while shaft kiln has high thermal efficiencyCooling system Vertical cooler, air-cooled conveyor Rapid cooling, waste heat recoveryDust removal system Cyclone dust collector, bag filter Exhaust gas purification to meet environmental requirements (3). Key points of process controlRaw material quality: CaCO₃ content ≥ 95%, SiO₂ + Al₂O₃ ≤ 2%.Calcination temperature: Too high will lead to over-burning (reduced densification activity), too low will lead to under-burning (residual CaCO₃).Fuel selection: Low-sulfur fuel (sulfur content < 0.5%) to avoid the formation of CaSO₄ that affects activity.Environmental requirements: Dust emission ≤ 10 mg/m³, CO₂ can be considered for capture and utilization (CCUS technology). 3.Active lime production process: How to systematically improve product quality?Active lime (CaO) is a vital raw material for modern industry. Its quality directly impacts process efficiency and product quality in key areas such as steelmaking, environmental desulfurization, and chemical production. As industrial technological requirements continue to increase, systematically improving the quality of active lime products has become a key focus of the industry. (1). Raw Material SelectionIn an activated lime production line, selecting the appropriate limestone raw material requires a comprehensive consideration of its chemical composition, physical properties, and actual production conditions. First, the limestone's CaCO₃ content should be as high as possible, ideally above 95%, to ensure high-purity activated lime after calcination. Impurity levels such as SiO₂ and Al₂O₃ must be strictly controlled, generally requiring SiO₂ to be no more than 1% and Al₂O₃ to be less than 0.5%. These impurities react with CaO at high temperatures to form low-melting calcium silicate or calcium aluminate, which not only reduces lime activity but also easily causes kiln ringing or nodules, impacting production stability. The content of harmful elements such as sulfur and phosphorus must be below 0.03%, especially for activated lime used in steelmaking. Excessive sulfur content can directly affect steel quality. In terms of physical properties, the limestone's particle size should be moderate, typically within the 30-50mm range. Too large a particle size prevents heat from reaching the core during calcination, resulting in premature burning. Too small a particle size can affect kiln ventilation and increase energy consumption. The hardness and porosity of the limestone also require attention. Moderate hardness and porosity help improve calcination efficiency and finished product quality. Furthermore, the limestone's mineral structure and crystallinity influence calcination results. Limestone with a finer grain structure is generally easier to decompose and more active after calcination. In actual production, raw material selection must be considered in conjunction with the kiln type. Rotary kilns are more adaptable to limestone particle sizes, while vertical kilns require a more uniform particle size distribution. Raw material supply stability and cost are also important considerations to ensure long-term economic and sustainable production. Laboratory analysis and industrial trials can further verify the suitability of limestone, ultimately selecting a raw material that meets quality requirements and is economically viable. (2). Raw material pretreatment In the active lime production line, the raw material pretreatment process is a key link to ensure the subsequent calcination efficiency and product quality. After the limestone raw materials are mined from the mine, they first need to be crushed and screened. The large pieces of limestone are crushed by jaw crusher, and then crushed by impact crusher or cone crusher. Finally, the raw materials are crushed to a uniform particle size of 30-50mm. This process must ensure that the particle size is moderate and avoid excessive crushing to produce too much powder, because too large particles will affect the calcination effect, and too small particles will lead to poor ventilation in the kiln. The crushed raw materials are graded and screened by vibrating screen to remove particles that are too large or too small that do not meet the requirements, and at the same time separate impurities such as soil and gravel to ensure the purity of the raw materials. The qualified limestone after screening needs to go through a cleaning process to remove the soil and dust attached to the surface by water washing or dry cleaning. This step is particularly important for improving the purity of the raw materials and reducing impurity reactions during the calcination process. The cleaned raw materials enter the drying system, where rotary dryers or other drying equipment are used to control the moisture content to below 1%. Excessive moisture not only increases calcination energy consumption but can also cause preheater blockage. The pretreated limestone is transported to the raw material silo for temporary storage. During this process, special attention must be paid to moisture and dust prevention measures to prevent secondary contamination of the raw materials and moisture absorption and agglomeration. The entire pretreatment process requires strict control of parameters at each stage to ensure that the raw materials' chemical composition, particle size, and moisture content meet calcination requirements, ensuring high-quality raw materials for the subsequent high-temperature calcination process. 4.Active Lime Production Line Maintenance GuideThe activated lime production line is a core production facility in the steel, chemical, environmental protection and other industries. Its stable operation is directly related to product quality, production efficiency and economic benefits. The maintenance and management of scientific systems can significantly reduce equipment failure rates, extend service life, and reduce energy consumption and production costs. (1) Main equipment and maintenance priorities of the production lineThe activated lime production line consists of multiple key equipment, each with its own specific maintenance requirements and priorities. Only by ensuring that every link is properly maintained can we ensure the efficient and stable operation of the entire production line. 1）. Raw material pretreatment systemThe raw material pretreatment system is the front-end link of the production line and mainly includes crushing equipment and screening equipment. Crushing equipment usually uses jaw crushers, impact crushers or cone crushers to crush limestone raw materials to appropriate particle size. The focus of maintenance is to regularly check the wear of the crusher jaw or hammer head, and it needs to be replaced in time when the wear on one side exceeds 15 mm. At the same time, attention should be paid to the bearing temperature and lubrication conditions. The bearing temperature should be controlled below 75 degrees Celsius, and the lubricating grease needs to be replenished or replaced regularly. The screening equipment is mainly a vibrating screen. It is necessary to check whether the screen is damaged every day. If the screen hole deformation exceeds 10%, it should be replaced immediately. In addition, the performance of the damper spring also needs to be tested regularly to ensure screening efficiency. 2）. calcination systemThe calcination system is the core part of the activated lime production line and mainly includes rotary kilns or vertical kilns. The maintenance of rotary kilns focuses on the mechanical condition of the kiln body and refractory materials. The ovality of the kiln body needs to be tested monthly, and the deviation should not exceed 0.2% of the kiln diameter. The wear of the contact surface between the supporting wheel and the belt should be checked regularly, and the gap should be controlled between 1-2 mm. The sealing device at the kiln head and kiln tail must maintain good sealing performance, and the air leakage rate must be controlled below 5%. The maintenance of refractory materials is particularly critical. The remaining thickness of the kiln lining should not be less than 80 mm. When local high temperature points are found by infrared temperature measurement, it often indicates that the refractory materials have fallen off and need to be treated in time. The maintenance of vertical kilns focuses on the combustion system and refractory materials. The nozzle of the burner needs to be cleaned weekly to prevent carbon deposits from affecting combustion efficiency. When the crack width of the hot surface layer of refractory materials exceeds 1 mm, it needs to be replaced. The temperature distribution in the kiln should be monitored through infrared temperature measurement, and the local temperature difference should not exceed 50 degrees Celsius. 3）. thermal systemThe thermal system includes preheaters, coolers and various fans and other equipment. The focus of the preheater maintenance is to prevent the cyclone from forming skin. It is necessary to shut down every 72 hours for air gun purging, and the accumulated thickness is controlled below 50 mm. The cooler should regularly check the wear of the grate plates, and the wear on one side should not exceed 5 mm, otherwise it will affect the cooling efficiency. The focus of fan maintenance is on the bearing vibration value and lubrication condition. The bearing vibration value should be controlled below 4.5 mm/s, and the lubricating grease needs to be replaced regularly. 4）. electrical control systemThe stable operation of the electrical control system is crucial to the entire production line. The DCS control cabinet needs to be cleaned every month to ensure good heat dissipation. Temperature, pressure and other sensors must be calibrated regularly, and the calibration period shall not exceed 3 months. The insulation resistance of the motor should be tested regularly, and the resistance value should not be lower than (2) Daily maintenance proceduresDaily maintenance is the first line of defense to prevent equipment failures. Through standardized daily inspection and maintenance, potential problems can be discovered and dealt with in a timely manner, preventing minor failures from turning into major problems. 1）. Daily inspection contentSystematic inspection of the entire line of equipment needs to be carried out every day. The raw material handling system must check the crusher bearing temperature, belt tension and screen condition. The calcination system must record the bearing temperature of supporting wheels at each stage of the rotary kiln and the movement of the kiln body, and check the sealing status of the kiln head and kiln tail. The thermal system shall monitor the preheater pressure difference, the cooler grate plate operation status and the fan vibration value. The electrical system must check whether the display of each instrument is normal and whether the operating current of the motor is within the rated range. Special attention needs to be paid to lubrication conditions. There are about 120-200 lubrication points in the entire production line, and lubricants need to be filled or replaced regularly according to equipment requirements. High-temperature parts such as kiln head bearings require high-temperature resistant grease, and lithium-based grease can be used for ordinary parts. The amount and cycle of lubricant filling must strictly comply with the requirements of the equipment manual. Too much or too little will affect the life of the equipment. 2）. Key parameter monitoringSeveral key parameters should be monitored in daily operation. The axial movement of the rotary kiln should be controlled within plus or minus 5 mm and achieved by adjusting the inclination angle of the supporting wheel. The range of motor current fluctuations should not exceed 10% of the rated value. Abnormal fluctuations often indicate mechanical blockage or electrical failure. The oxygen content of the exhaust gas should be maintained between 2-5%. If too high, it indicates that the system is leaking; if too low, it may be incomplete. 3）. Handling common problemsSome common problems encountered in daily maintenance need to be dealt with in a timely manner. If it is found that the discharge particle size of the crusher has become larger, it may be that the hammer head or jaw plate is excessively worn and needs to be inspected and replaced. When uneven contact between the rotary kiln wheel and the supporting wheel causes abnormal noise, the kiln body may be deviated and requires calibration with a laser centering instrument. The pressure difference of the dust collector suddenly increases. The filter bag may be damaged and needs to be stopped for inspection and replacement. (3) Regular maintenance planIn addition to daily maintenance, regular maintenance is a necessary measure to ensure long-term stable operation of equipment. According to the depth and scope of maintenance, it can be divided into monthly maintenance and annual overhaul. 1）. monthly maintenanceMonthly inspections are mainly aimed at wearing parts and key components. Refractory materials should be comprehensively inspected. The remaining thickness of rotary kiln lining should not be less than 50% of the original thickness. If the crack width of vertical kiln refractory bricks exceeds 1 mm, it needs to be treated. The transmission system must check the gear engagement of the reducer, and the contact area must reach more than 60%. The coupling alignment deviation should be controlled within 0.05 mm/meter. The insulation resistance of the motor should be tested, and the value should not be less than 100 megohm. During monthly maintenance of the lubrication system, the lubrication oil must be completely replaced and the oil circuit must be cleaned. The filter elements of the hydraulic system must be replaced, and the oil quality must meet the NAS 8 standard. The electrical system must check whether the wiring terminals are loose and whether the grounding resistance is qualified. 2）. annual overhaulThe annual overhaul is the time to carry out a comprehensive overhaul of the production line. The bending degree of the kiln body shall be tested with a laser straightener, and the deviation shall not exceed 0.1‰ of the kiln length. The preheater should be replaced with the wear-resistant lining of the cyclone. It is recommended to use ceramic wear-resistant materials, and the service life can reach 5 years. The electrical system must undergo comprehensive testing, including cable insulation testing, control system module testing, etc. During the overhaul, necessary renovations and upgrades will also be carried out to the equipment. If the three-level preheater is upgraded to a five-level preheater, the thermal efficiency can be increased by 25%; the ordinary cooler can be transformed into a push-rod cooler, the cooling efficiency can be increased by 40%. Although these renovations have a large one-time investment, they have significant long-term benefits. 3）. spare parts managementSound spare parts management is the foundation for ensuring smooth maintenance. Wearing parts such as crusher hammers and grate cooler grate plates should be kept in proper stock and purchased in advance according to the service life. Bulk spare parts such as refractories must be ordered 3-6 months in advance to ensure that they can be delivered in time during maintenance. Detailed warehouse entry and exit records must be established for all spare parts, and the principle of first-in, first-out shall be implemented. Through scientific daily maintenance and regular maintenance, the equipment failure rate of the activated lime production line can be reduced by more than 40%, the equipment life can be extended by 30%, and energy consumption can be reduced by 15%. Enterprises should establish a sound maintenance management system, form closed-loop management of point inspection, lubrication, overhaul, analysis and other aspects, and gradually introduce intelligent maintenance methods, such as predictive maintenance systems, digital twin technologies, etc., to further improve maintenance efficiency and accuracy. Only by maintaining equipment well can we ensure long-term stable and efficient operation of the production line and create maximum value for the company. 5.Common troubleshooting of active lime production lineAs an industrial system for continuous production, the activated lime production line will inevitably encounter various failures during long-term operation. Timely and accurate diagnosis and handling of these faults is the key to ensuring stable production and reducing downtime losses. (1) Fault handling of raw material pretreatment system1）. Crusher blockage failureFailure symptoms:Abnormal increase in current (exceeding 15% of rated value)Ununiform discharge particle size or completely interruptedIncreased equipment vibration accompanied by abnormal noise Reason analysis:The feed particle size is too large (exceeds the equipment design maximum)Material moisture content is too high (>5%)Foreign matter is stuck in the crushing chamberSevere wear of hammer/jaw plates leads to reduced crushing efficiency Treatment measures:Shut down immediately and cut off the powerClean the crushing chamber, inspect and remove foreign objectsCheck the status of the worn parts. The hammer head has a single side worn by more than 15mm and needs to be replaced.Adjust the feeding device to ensure that the material particle size is ≤ 80% of the design valuePre-drying the wet material Prevention recommendations:Install metal detectors and iron removal devicesEstablish a sampling system for feeding particle size (once every 2 hours)Set automatic overload protection device 2）. Vibration screen is damagedFailure symptoms:Large particulate material appears in the undersizeAbnormal movement trajectory of sieve bodyReduced screening efficiency Solution:Immediately stop the machine and replace the screen (when the damaged area is greater than 10%)Adjust the tensioning device to ensure that the screen installation flatness error is ≤3mmCheck the stiffness of the damping spring and replace the deformed spring (2) Troubleshooting of calcination system faults1）. Rotary kiln body deviationTypical performance:Uneven wear on the contact surface between the belt and the supporting wheelThe axial movement of the kiln body exceeds ±5mmDriving motor current fluctuates cyclically Processing steps:Use a laser centering instrument to detect the straightness of the kiln body (deviation>3mm/m needs to be adjusted)Corrected by the supporting roller adjustment device (each adjustment angle ≤0.5°)Check the wear condition of the wheel pad (gap>3mm needs to be replaced)Re-adjust the hydraulic gear pressure to 1.8-2.2MPa Key technical parameters:Kiln body ovality ≤0.2%D (D is kiln diameter)Roller bearing temperature ≤65℃Clearance between wheel and backing plate 1.5-2.5mm 2）. Shaft kiln nodules (kiln wall hanging material)Fault characteristics:Increase in resistance in the kiln (pressure difference> 30% of normal)The activity of lime exiting the kiln suddenly dropped below 280mlInfrared temperature measurement shows local high temperature area Emergency response plan:Reduce production by 20-30%Increase the temperature in the calcination zone by 50-80℃Put into operation the kiln wall vibrating device (frequency adjusted to 8-10Hz)Stop the kiln for manual cleaning if necessary (CO protection is required) Fundamental solutions:Control the content of SiO ˇ +Al ˇ O in raw materials to ≤2.5%Optimize the burner angle (tilt 5-8° is appropriate)Improve raw material pre-homogenization process (3) Thermal system fault handling1）. Preheater blockageFailure signs:Abnormal increase in system negative pressure (>6500Pa)The temperature of the lower cyclone dropped sharplyMaterial mobility deteriorates Emergency handling process:Stop feeding immediatelyTurn on the air cannon blocking system (cyclic action every 15 minutes)Use high-pressure water gun (pressure>10MPa) for remote cleaningCheck whether the spreader box is deformed (if the deformation exceeds 5mm, it needs to be replaced) Preventive maintenance:Check the skin formation of the cyclone every shiftControl the kiln tail exhaust gas temperature ≤350℃Optimize raw material composition (avoid enrichment of low-melting-point minerals) 2）. Grate cooler failureCommon problem types:Grate plate falling off: It is manifested by a short circuit of cooling air and an increase in discharge temperatureHydraulic system loss of pressure: abnormal running speed of grate bedTransmission chain breaks: equipment completely stops Treatment plan:Grate plate replacement standard: wear>5mm or through cracks appearHydraulic system maintenance:The oil temperature is controlled at 35-55℃Filter element replacement cycle ≤200 hoursChain tension adjustment: sag ≤ 2% of center distance (4) Electrical control system failure1）. DCS system signal abnormalFailure performance:Display value jumps or freezesControl instruction execution delayModule communication interruption Diagnosis steps:Check the grounding of the signal wire shielding layer (resistance ≤4Ω)Test channel isolator working statusVerify sensor output (4-20mA signal deviation ≤1%)Check the power supply quality of the control system (voltage fluctuation ≤±10%) 2）. Motor windings are overheatedProcessing process:Immediately stop the machine and measure the insulation resistance (≥100MΩ is qualified)Check the cooling system:Air-cooled motor: Clean up dust accumulated in air ductWater-cooled motor: check water pressure (≥0.2MPa) and flow rateCheck the mechanical load:Coupling alignment deviation ≤0.05mmBearing clearance meets standard (5) Principles for handling systemic faults1）. hierarchical fault response mechanismLevel 1 failure (risk of shutdown across the line): Activate emergency team within 15 minutesLevel 2 failure (partial shutdown): Develop a treatment plan within 2 hoursLevel 3 failure (operation can be maintained): included in the next maintenance plan 2）. Root Cause Analysis (RCA)Apply the 5Why analysis method for repetitive faults:Why did this happen?→ Direct causeWhy wasn't it discovered?→ Detect system defectsWhy not prevent it?→ Management system loopholes 3）. Emergency management of spare partsSafety inventory of critical spare parts (e.g. kiln head seals, hydraulic valve sets)Establish a regional spare parts sharing alliancePromote standardized spare parts (reduce the proportion of special parts) (6) Intelligent fault early warning technology1）. on-line monitoring systemVibration analysis: Capture early bearing defects (3-6 months warning before failure)Thermal imaging monitoring: identify refractory material falling off (alarm with temperature difference>50℃)Acoustic emission testing: crack propagation signal found 2）. Digital Twin ApplicationsSimulate through a virtual model:Equipment stress distributionWear trendfault propagation path 6.Frequently Asked Questions about Active Lime Production LineQ1: What is the optimal particle size range for limestone raw materials?A: Generally, it should be between 10-40mm. Particles that are too large (>50mm) will result in incomplete calcination, while particles that are too small (<5mm) will increase ventilation resistance in the kiln. Specific requirements for different kiln types are:Rotary kiln: 15-35mmVertical kiln: 20-40mm Q2: How should high mud content in raw materials be handled?A: The following measures are recommended:① Install a drum stone washer (mud removal efficiency can reach 80%)② Add pre-screening with a vibrating screen (3-5mm mesh)③ Control rainwater drainage from the storage yard (to avoid secondary pollution) Q3: What are the possible causes of large fluctuations in lime activity? A: The following factors need to be investigated:① Raw material factors: CaCO₃ content fluctuation > 3%, sudden increase in SiO₂② Thermal parameters: Calcination zone temperature fluctuation > ±30°C③ Cooling rate: Lime leaving the kiln does not cool to below 100°C within 90 seconds Q4: How should excessive free calcium oxide (f-CaO) in the finished product be handled?A: Control in stages:Short-term: Increase calcination temperature by 20-30°C and extend residence time by 10%Long-term: Optimize raw material ratio (control MgO content < 2%) Q5: Is the inverter frequently reporting overcurrent faults?A: Resolve these issues in this order:Check motor insulation (≥100MΩ)Test encoder feedback signal (deviation <0.5%)Optimize acceleration and deceleration times (>30s recommended for heavy-load starting). Q6: How should the CO concentration alarm (>50ppm) in the kiln be handled? A: Emergency Procedures:Immediately activate emergency ventilation (air volume ≥ 20 m³/min)Evacuate personnel and check oxygen levels (do not enter if oxygen levels < 19.5%)Check for gas pipeline leaks (soap and water leak detection method) Q7: How can I prevent refractory collapse during maintenance?A: Required procedures:① Ensure the kiln is fully cooled (internal temperature < 60°C)② Use support frames (spacing ≤ 1.5m)③ Strictly prohibit the simultaneous removal of more than three adjacent refractory bricks Q8: How to reduce coal consumption? (Currently > 120 kg standard coal per ton)A: Recommended Modification Options:Add a five-stage preheater (increase thermal efficiency by 25%)Install a kiln radiant heat recovery device (save coal by 8-12%)Use a low-NOx burner (save fuel by 5% and reduce NOx emissions) Practical AdviceEstablish a fault code library: Digitize historical faults and solutions for quick retrieval.Spare parts classification management: Category A spare parts (e.g., kiln main reducer gears) must be stocked on-site, while Category C spare parts can be purchased through negotiation.Weekly technical workshops: Analyze weekly faults and develop preventative measures