38 Common Desulfurization System Faults and Solutions

Desulfurization systems often encounter various problems, directly affecting the operation of the process system and causing economic losses. Today, we have compiled 30 common faults and solutions in desulfurization systems for you to tackle effectively.

1. Failure: Recirculation Pump Shutdown

Symptoms:

1. Audible and visual alarm signals indicating recirculation pump tripping.
2. Red light off and green light on, with the motor stopping rotation.
3. Lock-open of bypass damper, exhaust damper, shutdown of booster fan, and closure of inlet and outlet flue gas dampers of two units.

Causes:

1. Interruption in 6KV power supply.
2. Low absorption tower liquid level.
3. Malfunction in absorption tower liquid level control circuit.

Solutions:

1. Confirm proper operation of interlocking. Ensure automatic opening of bypass and ventilation dampers, booster fan tripping, and closure of flue gas dampers. If the interlocking is faulty, manually intervene.
2. Determine the cause of recirculation pump tripping and address it accordingly.
3. Promptly report to supervisors and relevant personnel for necessary actions.
4. If normal operation cannot be restored within a short time, follow the relevant regulations for temporary shutdown.
5. Monitor flue gas temperature and initiate demister flushing to prevent damage to the absorption tower lining and demister.

2. Failure: Process Water Interruption

Symptoms:

1. Low-pressure alarm signal for process water.
2. Interruption of water supply throughout the production site.
3. Decrease in related slurry tank levels.
4. Tripping of gypsum dewatering machine and vacuum pump.

Causes:

1. Malfunction of operating process water pump, failure of backup pump interlocking.
2. Closure of process water pump outlet valve.
3. Low level in process water tank causing pump tripping.
4. Rupture in process water pipeline.

Solutions:

1. Confirm proper interlocking of vacuum dewatering machine and vacuum pump.
2. Halt operation of gypsum discharge pump.
3. Immediately stop feeding and halt operation of filtrate water pump.
4. Identify the cause of process water interruption, report to supervisors promptly, and restore water supply as soon as possible.
5. Based on the levels in wash water tanks and filter cake wash water tanks, stop relevant pump operations.
6. Monitor absorption tower temperature, level, and limestone slurry tank level closely. Take necessary actions according to short-term shutdown regulations.

3. Failure: Desulfurization Booster Fan

Symptoms:

1. Audible and visual alarm indicating desulfurization booster fan tripping.
2. Red light off, yellow light on, and motor stopping rotation.
3. Automatic opening of desulfurization bypass damper, absorption tower ventilation damper, and closure of flue gas dampers.
4. Automatic slurry feeding stops when the system is on auto.

Causes:

1. Emergency button pressed.
2. Desulfurization booster fan power loss.
3. Recirculation pump shutdown.
4. Excessive pressure loss in desulfurization unit or improper closure of flue gas dampers.
5. High bearing temperature of booster fan.
6. High bearing temperature of motor.
7. High coil temperature of motor.
8. Excessive vibration in fan bearings.
9. Electrical faults (overload, overcurrent protection, differential protection tripping).
10. Booster fan surging.
11. High dust content in hot flue gas.
12. Low boiler load.

Solutions:

1. Confirm automatic opening of desulfurization bypass and absorption tower ventilation dampers, and automatic closure of flue gas dampers. If interlocking is faulty, intervene manually.
2. Investigate the cause of booster fan tripping. If it’s due to interlocking actions, restart after system returns to normal.
3. If the fault is due to equipment malfunction, promptly report to supervisors and contact maintenance personnel for repairs. Do not restart the fan until the fault is rectified.
4. If normal operation cannot be restored within a short time, follow short-term shutdown regulations.

4. Failure: 6KV Power Interruption

Symptoms:

1. Disappearance of 6KV busbar voltage, audible and visual alarm, CRT alarm.
2. Tripping of running desulfurization equipment, corresponding 6KV motors stopping operation.
3. Corresponding 380V busbars losing power, leading to tripping of corresponding 380V loads.

Causes:

1. Fault in 6KV busbar.
2. Trip of unit generator, failure of backup power supply to operate.
3. Desulfurization transformer failure, backup power supply not activated.

Solutions:

1. Confirm whether desulfurization interlock tripping actions are completed. If flue gas damper movements are faulty, switch to manual operation immediately.
2. Confirm normal supply to USP section and DC system, ensure work power switch and backup power switch are in off position, and disconnect all load switches.
3. Contact shift supervisor and electrical maintenance personnel to identify and rectify the fault and restore power supply promptly.
4. If feed system interlock is not activated, manually stop feeding.
5. Monitor temperature changes in flue gas system closely. If necessary, manually open demister flushing water valve.
6. Adjust booster fan baffle to minimum position in preparation for desulfurization unit restart.
7. If 6KV power supply cannot be restored in a short time, follow shutdown regulations and drain slurry from pipelines and pumps promptly to prevent sedimentation.
8. If 380V power interruption occurs, handle according to relevant regulations.

5. Failure: 380V Power Interruption

Symptoms:

1. Audible alarm for 380V power interruption.
2. Voltage indication drops to zero, low-voltage motors trip.
3. Work lighting trips, emergency lighting activates.

Causes:

1. Corresponding 6KV busbar fault.
2. Desulfurization low-voltage trip.
3. 380V busbar fault.

Solutions:

1. If caused by 6KV power supply failure, follow short-term shutdown procedures.
2. If it’s a single-section 380V fault, investigate the cause and equipment actions, and disconnect the power switch and load switch promptly. Report immediately.
3. If all 380V power is interrupted and cannot be restored within 8 hours, use backup equipment to drain all slurry from pumps and pipes and rinse them promptly.
4. Do not forcibly restore power supply if it was caused by electrical protection tripping.

6. Failure: GGH (Gas-Gas Heater) Malfunction

Symptoms: GGH malfunction.

Causes:

1. Motor overload or transmission device malfunction.
2. Excessive sealing or jamming.
3. Foreign object obstruction.
4. Guide bearing or support bearing damage.

Solutions:

1. Identify the cause and take appropriate action.
2. If current is too high or motor overheats, stop GGH operation and contact maintenance for inspection.

7. Failure: Gypsum Discharge Pump

Symptoms:

1. CRT alarm signal.
2. Audible and visual alarm for gypsum discharge pump.
3. Disappearance of outlet pressure and motor stoppage.

Causes:

1. Motor overload.
2. Low voltage or power loss.
3. Motor jamming.
4. Mechanical failure.

Solutions:

1. If motor overload, reduce load promptly and restart.
2. If it’s a voltage issue, restore power promptly.
3. Investigate and rectify any mechanical failures.

8. Failure: Circulating Pump Shutdown

Symptoms:

1. Audible and visual alarm for circulating pump.
2. Red light off and green light on.
3. Automatic opening of bypass damper, exhaust damper, and absorption tower ventilation damper.

Causes:

1. Interruption in 6KV power supply.
2. Low liquid level in the absorption tower.
3. Malfunction in the absorption tower liquid level control circuit.

Solutions:

1. Confirm interlocking actions are completed. If bypass and ventilation damper movements are faulty, intervene manually.
2. Determine the cause of the circulating pump trip and rectify.
3. If normal operation cannot be restored promptly, follow shutdown regulations.

9. Failure: High Temperature Alarm in Limestone Slurry Tank

Symptoms:

1. CRT alarm for high-temperature limestone slurry tank.
2. Audible and visual alarm for limestone slurry tank.

Causes:

1. Slurry pump tripping.
2. Circulating pump tripping.
3. Slurry spray tower tripping.

Solutions:

1. Investigate the cause and rectify promptly.
2. Monitor temperature changes and take necessary actions.

10. Failure: Sulfur Dioxide Analyzers Malfunction

Symptoms:

1. Sulfur dioxide analyzer malfunction.
2. Inaccurate SO2 concentration readings.

Causes:

1. Sensor failure.
2. Faulty analyzer equipment.

Solutions:

1. Replace the sensor.
2. Calibrate the analyzer.

11. Failure: Absorption Tower High Pressure Alarm

Symptoms:

1. Audible and visual alarm indicating high pressure in the absorption tower.
2. Red light off and yellow light on.
3. Automatic opening of bypass damper and exhaust damper.

Causes:

1. Interruption in limestone slurry pump operation.
2. Malfunction in the circulating pump.
3. Failure of slurry spray tower.

Solutions:

1. Investigate the cause of high pressure promptly and take necessary actions to reduce pressure.
2. Monitor pressure closely and adjust operating parameters as needed.

12. Failure: Limestone Slurry Pump Malfunction

Symptoms:

1. Audible and visual alarm for limestone slurry pump.
2. Disappearance of outlet pressure and motor stoppage.

Causes:

1. Motor overload.
2. Low voltage or power loss.
3. Mechanical failure.

Solutions:

1. If motor overload, reduce load promptly and restart.
2. If it’s a voltage issue, restore power promptly.
3. Investigate and rectify any mechanical failures.

13. Failure: Flue Gas Dampers Malfunction

Symptoms:

1. Flue gas damper malfunction.
2. Inaccurate positioning or failure to open/close.

Causes:

1. Mechanical failure.
2. Electrical malfunction.
3. Control system failure.

Solutions:

1. Investigate the cause of damper malfunction and take corrective action.
2. Check for any obstructions or damage to the dampers.
3. Repair or replace faulty components as needed.

14. Failure: Slurry Spray Tower Malfunction

Symptoms:

1. CRT alarm for slurry spray tower.
2. Audible and visual alarm for slurry spray tower.

Causes:

1. Pump failure.
2. Nozzle clogging.
3. Low liquid level in the tower.

Solutions:

1. Investigate the cause of malfunction and take corrective action.
2. Clean or replace clogged nozzles.
3. Ensure proper liquid level in the tower.

15. Failure: Desulfurization System Instrumentation Failure

Symptoms:

1. Inaccurate readings from instrumentation.
2. Instrument alarms and warnings.

Causes:

1. Sensor failure.
2. Instrument calibration issues.
3. Wiring or connection problems.

Solutions:

1. Calibrate or replace faulty sensors.
2. Check and recalibrate instrumentation as needed.
3. Inspect wiring and connections for any issues and repair as necessary.

16. Failure: Gypsum Dewatering System Malfunction

Symptoms:

1. Audible and visual alarm for gypsum dewatering system.
2. Disappearance of outlet pressure and motor stoppage.

Causes:

1. Motor overload.
2. Low voltage or power loss.
3. Mechanical failure.

Solutions:

1. If motor overload, reduce load promptly and restart.
2. If it’s a voltage issue, restore power promptly.
3. Investigate and rectify any mechanical failures.

17. Failure: Slurry Tank Overflow

Symptoms:

1. High liquid level alarm in slurry tank.
2. Overflow of slurry from tank.

Causes:

1. Pump malfunction.
2. Control system failure.
3. Inadequate capacity of slurry tank.

Solutions:

1. Stop pump operation to prevent further overflow.
2. Investigate the cause of overflow and take corrective action.
3. Increase capacity of slurry tank if necessary.

18. Failure: Flue Gas Temperature Abnormalities

Symptoms:

1. High or low temperature alarm for flue gas.
2. Fluctuating temperature readings.

Causes:

1. Fuel combustion issues.
2. Air flow imbalance.
3. Heat exchanger malfunction.

Solutions:

1. Adjust fuel and air flow rates to maintain desired temperature.
2. Inspect and clean heat exchanger components.
3. Balance air flow distribution in the system.

19. Failure: Corrosion in Absorption Tower

Symptoms:

1. Visible corrosion or degradation of tower materials.
2. Leakage or structural weakening.

Causes:

1. Exposure to corrosive gases.
2. Inadequate material selection.
3. Poor maintenance practices.

Solutions:

1. Implement corrosion-resistant materials in tower construction.
2. Regularly inspect and maintain tower components.
3. Monitor gas composition and adjust process parameters as needed.

20. Failure: Scrubber Pump Malfunction

Symptoms:

1. Audible and visual alarm for scrubber pump.
2. Disappearance of outlet pressure and motor stoppage.

Causes:

1. Motor overload.
2. Low voltage or power loss.
3. Mechanical failure.

Solutions:

1. If motor overload, reduce load promptly and restart.
2. If it’s a voltage issue, restore power promptly.
3. Investigate and rectify any mechanical failures.

21. Failure: Pump Seal Leakage

Symptoms:

1. Visual observation of leakage around pump seals.
2. Decrease in pump efficiency.
3. Increase in pump motor temperature.

Causes:

1. Wear and tear of pump seals over time.
2. Excessive pump pressure.
3. Improper installation of seals.

Solutions:

1. Replace worn-out pump seals promptly.
2. Monitor and adjust pump pressure to prevent excessive stress on seals.
3. Ensure proper installation and alignment of seals according to manufacturer specifications.

22. Failure: Sulfur Dioxide (SO2) Emission Exceeding Regulatory Limits

Symptoms:

1. Detection of high levels of sulfur dioxide in flue gas emissions.
2. Regulatory violations and potential fines.
3. Public health concerns and community complaints.

Causes:

1. Inefficient desulfurization process.
2. Equipment malfunction or breakdown.
3. Poor maintenance practices.

Solutions:

1. Optimize desulfurization process parameters for maximum efficiency.
2. Conduct regular maintenance and inspections to ensure equipment integrity.
3. Implement emission monitoring and control systems to detect and mitigate excess SO2 emissions.

23. Failure: Corrosion in Ductwork

Symptoms:

1. Visible signs of corrosion on duct surfaces.
2. Structural weakening or perforation of ducts.
3. Potential release of harmful gases into the environment.

Causes:

1. Exposure to corrosive gases such as sulfur dioxide and hydrogen sulfide.
2. Inadequate material selection for duct construction.
3. Lack of corrosion protection measures.

Solutions:

1. Use corrosion-resistant materials such as stainless steel or fiberglass for duct construction.
2. Apply protective coatings or linings to duct surfaces to prevent corrosion.
3. Implement regular inspection and maintenance procedures to identify and address corrosion issues early.

24. Failure: High Energy Consumption

Symptoms:

1. Significant increase in energy bills.
2. Inefficient operation of desulfurization equipment.
3. Environmental impact due to excessive energy consumption.

Causes:

1. Suboptimal process design or operating parameters.
2. Equipment inefficiencies or malfunctions.
3. Lack of energy-saving measures or technologies.

Solutions:

1. Conduct energy audits to identify areas of inefficiency and potential savings.
2. Optimize process parameters and equipment operation to minimize energy consumption.
3. Implement energy-saving technologies such as variable frequency drives, heat recovery systems, and energy-efficient motors.

25. Failure: Sulfur Buildup in Equipment

Symptoms:

1. Accumulation of sulfur deposits on equipment surfaces.
2. Reduction in equipment performance and efficiency.
3. Increased risk of equipment damage or failure.

Causes:

1. Incomplete sulfur removal during desulfurization process.
2. Improper cleaning or maintenance practices.
3. Insufficient temperature or residence time in desulfurization equipment.

Solutions:

1. Optimize desulfurization process parameters to ensure complete sulfur removal.
2. Implement regular cleaning and maintenance schedules to prevent sulfur buildup.
3. Increase temperature or residence time in desulfurization equipment as needed to improve sulfur removal efficiency.

26. Failure: Pump Motor Overheating

Symptoms:

1. Elevated motor temperature.
2. Increased energy consumption.
3. Risk of motor damage or failure.

Causes:

1. Excessive load on the pump motor.
2. Insufficient cooling or ventilation.
3. Electrical issues such as voltage fluctuations or motor winding faults.

Solutions:

1. Reduce pump load or upgrade to a larger motor if necessary.
2. Improve cooling and ventilation around the motor.
3. Address any electrical issues promptly through inspection and maintenance.

27. Failure: Inadequate Flue Gas Desulfurization Efficiency

Symptoms:

1. High sulfur dioxide emissions.
2. Compliance violations with regulatory standards.
3. Environmental and health concerns.

Causes:

1. Suboptimal desulfurization process parameters.
2. Equipment malfunction or deterioration.
3. Insufficient reagent supply or distribution.

Solutions:

1. Optimize desulfurization process parameters such as reagent concentration, temperature, and contact time.
2. Conduct regular maintenance and inspections to ensure proper equipment function.
3. Ensure adequate reagent supply and distribution throughout the desulfurization system.

28. Failure: Corrosion of Absorber Tower

Symptoms:

1. Visible signs of corrosion on tower surfaces.
2. Structural weakening or integrity loss.
3. Potential leaks or releases of harmful substances.

Causes:

1. Exposure to corrosive gases and chemicals in flue gas.
2. Inadequate material selection or protective coatings.
3. Lack of maintenance or corrosion control measures.

Solutions:

1. Use corrosion-resistant materials and coatings for tower construction.
2. Implement corrosion monitoring and maintenance programs.
3. Apply inhibitors or protective coatings to mitigate corrosion effects.

29. Failure: Erosion of Absorber Packing Material

Symptoms:

1. Decrease in absorption efficiency.
2. Physical degradation or displacement of packing material.
3. Potential release of unabsorbed pollutants.

Causes:

1. High gas velocity or turbulence in the absorber.
2. Abrasive particles or contaminants in flue gas.
3. Inadequate design or maintenance of packing material.

Solutions:

1. Optimize absorber design to minimize gas velocity and turbulence.
2. Install erosion-resistant packing materials or coatings.
3. Implement regular inspection and replacement of packing material as needed.

30. Failure: Insufficient Waste Disposal Management

Symptoms:

1. Accumulation of waste byproducts from desulfurization process.
2. Environmental pollution and contamination.
3. Regulatory compliance issues.

Causes:

1. Inadequate waste storage or disposal facilities.
2. Lack of proper waste treatment or recycling options.
3. Failure to comply with waste management regulations.

Solutions:

1. Develop comprehensive waste management plans for handling and disposal of desulfurization byproducts.
2. Implement waste treatment technologies such as filtration, precipitation, or chemical stabilization.
3. Ensure compliance with local environmental regulations regarding waste disposal and recycling.

31. Failure: Scaling in Heat Exchangers

Symptoms:

1. Reduced heat transfer efficiency.
2. Increased energy consumption.
3. Potential damage to heat exchanger components.

Causes:

1. Accumulation of mineral deposits such as calcium carbonate or magnesium sulfate.
2. Poor water quality or improper chemical treatment.
3. Inadequate maintenance or cleaning procedures.

Solutions:

1. Implement water quality monitoring and treatment to prevent scaling.
2. Regularly clean heat exchanger surfaces using appropriate chemical or mechanical methods.
3. Consider alternative heat exchanger materials or coatings to mitigate scaling effects.

32. Failure: Corrosion in Boiler Tubes

Symptoms:

1. Leakage or rupture of boiler tubes.
2. Reduced steam quality and efficiency.
3. Risk of boiler failure or explosion.

Causes:

1. Exposure to corrosive gases or chemicals in combustion flue gas.
2. Inadequate water treatment or pH control.
3. High temperatures and pressure conditions within the boiler.

Solutions:

1. Use corrosion-resistant materials for boiler tube construction.
2. Implement effective water treatment and corrosion control measures.
3. Monitor boiler conditions regularly and perform maintenance as needed to prevent corrosion.

33. Failure: Fouling in Air Preheaters

Symptoms:

1. Reduced heat transfer efficiency.
2. Increased fuel consumption.
3. Potential damage to preheater surfaces.

Causes:

1. Accumulation of dust, ash, or other particulate matter on preheater surfaces.
2. Poor combustion or fuel quality.
3. Inadequate cleaning or maintenance of preheater components.

Solutions:

1. Improve combustion efficiency and reduce particulate emissions to minimize fouling.
2. Implement regular cleaning and maintenance schedules for preheater surfaces.
3. Consider the use of anti-fouling coatings or technologies to prevent buildup.

34. Failure: Poor Control System Performance

Symptoms:

1. Inaccurate monitoring or control of process parameters.
2. Fluctuations in system operation and efficiency.
3. Increased risk of equipment damage or failure.

Causes:

1. Malfunctioning sensors, actuators, or control valves.
2. Inadequate tuning or calibration of control algorithms.
3. Lack of integration or communication between control system components.

Solutions:

1. Conduct regular inspection and maintenance of control system components.
2. Optimize control algorithms and tuning parameters for improved performance.
3. Implement advanced control strategies and automation technologies to enhance system reliability and efficiency.

35. Failure: Steam Turbine Blade Erosion

Symptoms:

1. Reduced turbine efficiency and power output.
2. Increased vibration and wear on turbine components.
3. Risk of blade failure or catastrophic turbine damage.

Causes:

1. Impact of solid particles carried by steam flow.
2. Improper steam quality or wet steam conditions.
3. Inadequate turbine design or maintenance practices.

Solutions:

1. Implement steam conditioning measures to reduce moisture and impurities.
2. Install erosion-resistant coatings or materials on turbine blades.
3. Monitor turbine condition regularly and perform inspections to detect erosion damage early.

36. Failure: Transformer Insulation Degradation

Symptoms:

1. Increased transformer temperature and loading.
2. Power quality issues such as voltage fluctuations or harmonics.
3. Risk of insulation breakdown and electrical faults.

Causes:

1. Thermal aging and degradation of insulation materials.
2. Exposure to moisture, contaminants, or chemical pollutants.
3. Overloading or improper operation of the transformer.

Solutions:

1. Perform regular testing and diagnostics to assess insulation condition.
2. Implement preventive maintenance measures such as cleaning and drying of transformer insulation.
3. Consider retrofitting or replacing aging transformers with newer, more reliable units.

37. Failure: Cooling Tower Fouling

Symptoms:

1. Reduced heat rejection efficiency.
2. Increased energy consumption for cooling.
3. Risk of equipment damage due to overheating.

Causes:

1. Accumulation of algae, sediment, or scale deposits in cooling tower fill or spray nozzles.
2. Poor water quality or inadequate treatment.
3. Ineffective cleaning or maintenance practices.

Solutions:

1. Implement water treatment and filtration to prevent fouling.
2. Regularly inspect and clean cooling tower components.
3. Consider upgrades or modifications to cooling tower design to improve performance and reduce fouling.

38. Failure: Boiler Feedwater Pump Cavitation

Symptoms:

1. Vibration and noise from the pump.
2. Reduced pump efficiency and flow rate.
3. Risk of pump damage or failure.

Causes:

1. Insufficient net positive suction head (NPSH) available.
2. High fluid velocity or pressure fluctuations.
3. Poor pump design or improper operation.

Solutions:

1. Ensure adequate NPSH margin by adjusting pump installation or system configuration.
2. Control fluid velocity and pressure to prevent cavitation.
3. Select appropriate pump design and materials to withstand cavitation effects.

By addressing these additional failure scenarios and implementing appropriate solutions, you can enhance the reliability and performance of your power plant equipment and systems.