Rotary Dryer Troubleshooting: Causes & Fixes

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Problems on this page:

Wet product or under-drying Build-up or ringing inside the drum Drive, seal or tyre/roller fault Fire or smouldering in the dryer Dust at the stack or around the drum Burner lockouts Product discoloured or degraded Feed chute blockage

Wet product or under-drying

Hits OEE: Quality

Symptoms: Product moisture too high, inconsistent drying, downstream issues.

Inlet temperature or airflow low

Set the temperature/airflow; check the burner and fans.

Feed rate or moisture variation

Control feed rate and incoming moisture.

Flights worn (poor showering)

Inspect and repair lifting flights for good material curtain.

Prevention: Temperature/airflow control, feed control, flight maintenance.

Build-up or ringing inside the drum

Hits OEE: Availability

Symptoms: Material rings/builds inside, reduced capacity, imbalance.

Sticky moisture zone / temperature profile

Adjust the profile; manage the sticky zone; recycle dry product.

Worn flights causing dead zones

Repair/replace flights.

Feed consistency

Stabilise feed moisture and rate.

Prevention: Profile control, flight upkeep, feed stability.

Drive, seal or tyre/roller fault

Hits OEE: Availability

Symptoms: Drum drifts, seal leaks/air ingress, drive trips, hot rollers.

Tyre/trunnion-roller wear or misalignment

Align the drum; service tyres and support rollers.

Seal wear (air ingress)

Replace drum seals to control air leakage.

Drive/girth-gear or thrust fault

Check the drive, girth gear and thrust rollers.

Prevention: Alignment, seal upkeep, drive/roller maintenance.

Fire or smouldering in the dryer

Hits OEE: Availability

Symptoms: Smouldering product, temperature spikes at the outlet, burnt particles in the product.

Inlet temperature too high for the product

Keep the inlet temperature within the limits set for the product.

Product build-up in the drum and ducts

Clean the drum, flights and ducts on a schedule.

Fire detection or suppression not maintained

Test the detection and suppression systems as their makers require.

Hot shutdown with product left inside

Follow a shutdown sequence that cools and empties the drum.

Prevention: Inspection for build-up after every campaign.

Dust at the stack or around the drum

Hits OEE: Quality

Symptoms: Visible dust at the stack, product carried into the exhaust, dust around the seals.

Cyclone or bag filter not working well

Check the separators, their discharge valves and the filter pressure drop.

Airflow higher than the product needs

Reduce the airflow so fine product is not carried out.

Worn drum seals

Replace the inlet and outlet seals.

Prevention: Stack and seal checks on the route.

Burner lockouts

Hits OEE: Availability

Symptoms: The burner fails to light or locks out and the dryer stops.

Flame detector dirty or failed

Clean or replace the flame detector.

Fuel pressure low or unstable

Check the fuel supply and regulator.

Combustion air fan or air switch fault

Check the fan and the air proving switch.

Prevention: Burner servicing by a qualified technician on the maker's schedule.

Product discoloured or degraded

Hits OEE: Quality

Symptoms: Darkened, scorched or degraded product leaving the dryer.

Product over-dried

Lower the inlet temperature or raise the feed rate.

Residence time too long

Check drum speed and slope against the design.

Hot spots from poor air distribution

Check the air distribution and the flights.

Prevention: Product colour and moisture checked together.

Feed chute blockage

Hits OEE: Availability

Symptoms: Feed backs up at the inlet and the dryer starves.

Wet, sticky feed

Check the feed moisture and consider back-mixing dry product.

Chute angle too shallow for the material

Steepen or line the chute.

Build-up at the inlet seal

Clean the inlet area on a schedule.

Prevention: Inlet checks on the route.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Related equipment guides: spray dryer · steam boiler · industrial oven · tunnel pasteuriser · pellet mill

Stop the same fault coming back

Recurring rotary dryer stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

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Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover