What are the troubleshooting and maintenance methods for centrifugal spray dryers?

Troubleshooting and maintenance for centrifugal spray dryers should focus on core systems, encompassing atomization, hot air, exhaust ventilation, electrical components, and safety features. Specific maintenance procedures are as follows:

Atomization System Maintenance

Atomization Disc/Nozzle Care:

After daily use, disassemble the centrifugal atomization disc. Clean crevices with a soft-bristle brush dipped in neutral detergent, rinse thoroughly with water, and air-dry.

For pressure-type nozzles, use a needle to clear orifices and prevent blockages.

If uneven atomization or abnormal rotational speed occurs, calibrate the motor or replace worn components.

Rotational Speed and Pressure Regulation:

Monitor atomizer speed via the PLC system. If speed is low, inspect bearing lubrication (high-temperature grease must fully coat surfaces) or gear wear.

Adjust feed pump pressure to match atomization requirements, preventing powder leakage or wall adhesion.

Hot Air System Maintenance

Temperature Control:

Inlet air temperature must remain stable at setpoint (deviation ≤ ±2°C). If overheating occurs, inspect heater faults or thermocouple failures.

When outlet temperature is too low (e.g., <40°C), reduce feed rate or increase hot air inlet temperature.

Duct Cleaning:

Weekly compressed air cleaning of air filters; shift-by-shift cleaning of primary filters.

If coking occurs on hot air duct walls (localized temperatures >200°C), shut down for cleaning and adjust air intake parameters.

Exhaust System Maintenance

Cyclone Separator Inspection:

Monthly airtightness testing (negative pressure ≤3000Pa). Tighten connections or replace seals if leaks occur.

Clean material buildup in the cone section with a high-pressure water jet (0.3-0.5MPa). Soak stubborn residues in warm water before wiping dry.

Baghouse Dust Collector Maintenance:

Perform reverse-air cleaning or replace filter bags when differential pressure exceeds 2000Pa.

If exhaust dust levels exceed standards, inspect pulse valves or grounding wires to ensure emissions comply with environmental regulations.

Electrical System Maintenance

Circuit Inspection:

Use a multimeter to verify power supply voltage stability (three-phase voltage balance, fluctuation <±10%). Investigate short circuits or poor contacts.

When PLC/touchscreen freezes, power down and restart or perform programming diagnostics.

Sensor Calibration:

Quarterly calibration of inlet/outlet temperature sensors using a standard thermometer (adjust if deviation >±1℃).

Periodically test sensitivity of pressure gauges and vacuum gauges.

Mechanical Condition Monitoring and Maintenance

Operating Parameter Logging:

Record hourly parameters including temperature, pressure, flow rate, and current. Immediately investigate abnormal fluctuations (e.g., sudden feed rate increase >10%).

Mechanical Condition Inspection:

Check motor/bearing temperatures (normal <60°C). Abnormal heating requires inspection for oil port blockage or cooling water pipe issues.

Shut down for inspection if equipment vibrates or emits abnormal noise to check for shaft bending, gear wear, or poor lubrication.

Other Maintenance Points

Explosion Prevention and Protection:

Maintain oxygen concentration <3% in closed-loop systems. Strictly prohibit opening inspection doors during operation.

Equip fire extinguishers around equipment. Operators must be trained in emergency shutdown procedures.

Air Leak and Leakage Inspection:

Check for air leaks at pipe and valve connections. Replace aged seals promptly.

Immediately shut down and clean up any liquid leaks to prevent component corrosion.

Cleaning Method Selection:

Choose dry cleaning (brush/vacuum), wet cleaning (60-80°C hot water), or chemical cleaning (1%-2% HNO₃ acid wash or 0.5%-1% NaOH alkali wash, temperature ≤65°C) based on production conditions.

Follow cleaning with high-temperature sterilization (15-30 min).

Critical Component Cleaning:

Regularly clean the inner walls of drying towers, cyclone separators, and collection vessels to prevent residue buildup.

Clean air filter screens every 3-6 weeks. Apply light spindle oil to stainless steel wires for rust prevention.