What are the Common Faults of Grain Dryers?

Category： Industry News

Time： 2025-11-27

Summary： Common faults of grain dryers mainly concentrate on five core modules: heat source system, transmission system, ventilation system, control system, and material flow system.

　　Common faults of grain dryers mainly concentrate on five core modules: heat source system, transmission system, ventilation system, control system, and material flow system. Most faults are related to improper operation, lack of maintenance, environmental factors (e.g., rainy and humid weather in Southwest China), or component aging. Below is a classified analysis of high-frequency faults, their causes, troubleshooting methods, and targeted solutions for Southwest China, balancing practicality and professionalism:

　　I. Heat Source System Faults (Core Module, Directly Affecting Drying Efficiency)

　　The heat source system is the "heart" of the dryer. Faults can cause abnormal hot air temperature, insufficient heat, or even shutdown, commonly occurring in biomass, oil-fired, and gas-fired heat sources:

Common FaultsTypical ManifestationsCore Causes (Including Southwest China Characteristics)Troubleshooting & Solutions
Insufficient/Fluctuating Hot Air TemperatureActual temperature only 40℃ when set to 60℃; temperature fluctuates drastically1. Insufficient fuel supply (moisture-induced caking of biomass pellets, clogged oil filters, low gas pressure);2. Burner malfunctions (carbon deposits on ignition electrodes, clogged nozzles, faulty flame detectors);3. Heat exchanger fouling/coking (high impurity content in biomass fuel in Southwest China causes frequent coking);4. Blocked air inlets (dust caking in humid environments)1. Inspect fuel: Ensure biomass pellet moisture ≤15%, drain oil/sewage from fuel filters, and maintain gas pipeline pressure ≥0.2MPa;2. Clean the burner: Wipe electrodes, unclog nozzles, and replace faulty flame detectors;3. Clean the heat exchanger: Remove fouling/coking with high-pressure water + descaling agents (weekly for biomass heat sources);4. Clean inlet filters (check before daily operation)
Incomplete Combustion/Black Smoke EmissionBlack smoke from the chimney; unburned fuel residue in the furnace1. Insufficient air supply (low fan air volume, closed air intake dampers);2. Imbalanced fuel-air mixture ratio (poor oil atomization, clogged gas nozzles);3. Excessive impurities in biomass fuel (incompletely crushed straw)1. Check fan operation, open air intake dampers, and clear duct blockages;2. Adjust burner dampers (increase air intake) and clean oil atomizing nozzles;3. Screen biomass pellets (remove impurities, particle size 6-8mm)
Heat Source System Leakage (Gas/Oil)Smell of gas, oil stains on the ground, accompanied by alarms1. Aging seals at pipeline joints (humidity in Southwest China accelerates rubber component aging);2. Damaged gas valves or cracked oil pipelines;3. Loose connecting bolts (caused by equipment vibration)1. Immediately shut down the equipment, cut off fuel supply, and ventilate (no ignition allowed);2. Inspect pipeline joints, replace aging gaskets, and tighten bolts;3. Detect gas leaks with soapy water (bubbles indicate leakage points) and replace damaged valves
Severe Coking in Biomass Combustion FurnacesThick coking on furnace walls; sudden drop in heat exchange efficiency1. High ash content in fuel (unscreened straw briquettes);2. Excessively high furnace temperature (exceeding 120℃);3. Infrequent ash removal (no daily cleaning after operation)1. After the furnace cools down, remove coking with steel brazes (avoid hard knocking to prevent furnace lining damage);2. Reduce hot air temperature (control at 80-100℃) and mix with high-quality biomass pellets;3. Install a secondary air device (promote full combustion and reduce coking)

 

　　II. Transmission System Faults (Affecting Operational Continuity)

　　The transmission system includes motors, fans, chains, gears, conveyors, and elevators. Faults are often manifested as abnormal noise, jamming, or shutdown, related to insufficient lubrication, wear, or overload:

Common FaultsTypical ManifestationsCore CausesTroubleshooting & Solutions
Motor Overheating/TrippingMotor housing temperature ≥70℃; circuit breaker trips1. Overload operation (drying capacity exceeds rated capacity);2. Insufficient bearing lubrication (no regular oiling);3. Motor moisture (water ingress in electrical components due to rainy weather in Southwest China);4. Aging and short-circuit of wires1. Reduce feed quantity and cool the motor by idling for 10 minutes;2. Remove the motor end cover and apply lithium-based grease (every 50 hours);3. Inspect the motor junction box, replace moisture-damaged components, and install rain shields;4. Test the circuit with a multimeter and replace aging wires
Fan Abnormal Noise/Excessive Vibration"Hum" noise or severe vibration during fan operation1. Imbalanced impeller due to dust accumulation (center of gravity shift);2. Bearing wear (lack of oil or aging);3. Loose fan fixing bolts (caused by equipment vibration)1. Shut down and clean impeller dust (blow with compressed air);2. Check bearing clearance (replace if exceeding 0.5mm) and add lubricating oil;3. Tighten fan base bolts and install shock absorbers
Chain/Gear Jamming/BreakageTransmission chain jamming or falling off; abnormal noise during gear meshing1. Insufficient lubrication (dry friction wear);2. Improper chain tension (slippage if too loose, breakage if too tight);3. Gear tooth wear (no replacement after long-term use)1. Apply gear oil/chain oil (every 50 hours);2. Adjust the tensioner to keep chain sag ≤10mm;3. Replace severely worn chains/gears (replace if gear tooth wear exceeds 1/3)
Elevator/Conveyor Belt SlippageElevator fails to feed; conveyor belt idles1. Insufficient belt tension;2. Oil/dust on the belt surface (causing slippage);3. Overfeeding (jamming due to overload)1. Adjust the belt tension device (tighten bolts);2. Wipe the belt surface (remove oil/dust) and replace with anti-slip belts if necessary;3. Clear clogged grain in the elevator and reduce feed quantity

 

　　III. Ventilation System Faults (Affecting Drying Uniformity and Energy Consumption)

　　The ventilation system includes fans, air ducts, air outlets, and filters. Faults can cause poor hot air circulation, inadequate moisture discharge, leading to uneven drying and grain moisture regain:

Common FaultsTypical ManifestationsCore Causes (Including Southwest China Characteristics)Troubleshooting & Solutions
Duct Blockage/Insufficient Hot Air PenetrationIncomplete drying of some grain layers (outer dry, inner wet); low air volume at the outlet1. Residual grain/impurities in air ducts (no timely cleaning);2. Clogged filters (dust caking in humid Southwest China);3. Uneven grain distribution (distributor malfunction)1. Shut down and clear residual grain/impurities in ducts (blow with compressed air);2. Replace or clean filters (check after daily operation);3. Overhaul the distributor (adjust the speed of rotary distributors for uniform feeding)
Grain/Dust Emission from Air OutletGrain particles discharged from the air outlet; severe dust pollution1. Damaged screens (aging of cleaning device screens);2. Excessively thin grain layer (hot air speed too high blows up grain);3. Dust collector malfunction (no timely ash removal from hoppers)1. Replace damaged screens and inspect the cleaning device;2. Adjust feed quantity to thicken the grain layer (control at 30-80cm);3. Clean dust collector hoppers (daily after operation)
Moist Hot Air Backflow/CondensationCondensation on equipment inner walls; grain moisture regain and mold1. Uninsulated air outlet pipelines (temperature difference in Southwest China causes condensation of moist hot air);2. Improper air outlet position (facing cold air);3. Insufficient ventilation in the cooling section1. Wrap air outlet pipelines with insulation cotton;2. Adjust the air outlet direction (avoid facing cold air);3. Check the cooling fan operation and clear ventilation holes in the cooling section

 

　　IV. Control System Faults (Affecting Automated Operation, Prone to Operational Errors)

　　The control system includes PLC, sensors, contactors, and relays. Faults are often manifested as inaccurate parameters, faulty alarms, or failure to shut down automatically, related to humidity, dust, or wiring issues:

Common FaultsTypical ManifestationsCore CausesTroubleshooting & Solutions
Inaccurate Moisture Sensor DetectionGrain moisture deviation >±1% after drying; over-drying or under-drying1. Contaminated sensor probes (covered with dust/grain residues);2. Expired sensor calibration (no regular calibration);3. Sensor moisture (short circuit caused by humidity in Southwest China)1. Wipe sensor probes with a dry cloth (check before daily operation);2. Calibrate with a standard moisture meter (every 200 hours);3. Replace moisture-damaged sensors and install dehumidifiers in control cabinets
Abnormal Temperature Display/Faulty AlarmTemperature displays 0℃ or far exceeds the set value; no alarm prompt1. Temperature sensor disconnection/short circuit;2. Ablated contactors (poor contact at contacts);3. PLC program disorder (caused by power fluctuations)1. Test sensor wiring with a multimeter (rewire if disconnected, replace if short-circuited);2. Replace ablated contactors/relays;3. Restart the PLC and back up programs (avoid data loss)
Failure to Auto Start/Stop/Grain DischargeManual operation required; auto mode ineffective1. Travel switch malfunction (switch not triggered by the grain discharge mechanism);2. Loose control wiring (caused by equipment vibration);3. Triggered overload protection (no reset)1. Inspect the travel switch and adjust its position (ensure triggering during discharge);2. Tighten control wiring joints;3. Identify the cause of overload (e.g., jamming) and press the reset button

 

　　V. Material Flow System Faults (Affecting Operational Continuity, Prone to Equipment Jamming)

　　The material flow system includes drying bins, grain discharge mechanisms, and level gauges. Faults are often manifested as grain blockages or uneven discharge, related to improper feeding or component wear:

Common FaultsTypical ManifestationsCore Causes (Including Southwest China Characteristics)Troubleshooting & Solutions
Drying Bin Blockage/Arch FormationGrain accumulates and cakes in the bin; unable to fall1. Excessively high grain moisture (wet grain moisture >25% due to rainy weather in Southwest China);2. Insufficient bin wall smoothness (moldy and caked residual grain);3. Grain discharge mechanism malfunction (auger/discharge wheel jamming)1. Reduce feed moisture (control wet grain moisture ≤20%, pre-dry if necessary);2. Clear caked grain in the bin (tap the bin wall with wooden sticks to assist falling, avoid hard knocking);3. Overhaul the grain discharge mechanism and clear jammed impurities
Uneven/Intermittent Grain DischargeDischarge speed fluctuates or stops suddenly1. Wear of discharge wheels (uneven feeding due to tooth wear);2. Faulty level gauges (no grain detection, stopping discharge);3. Fluctuating feed quantity (uneven manual feeding)1. Replace worn discharge wheels;2. Inspect level gauges (clean probe dust and calibrate sensitivity);3. Adopt quantitative feeding devices (e.g., screw conveyors) for stable feeding
Excessively High Grain Breakage/Cracking RateSevere grain damage after drying; quality degradation1. Excessively high hot air temperature (exceeding grain tolerance);2. Too fast discharge speed (no complete tempering stage);3. Excessive vibration of transmission components (grain collision and wear)1. Reduce hot air temperature (rice ≤60℃, corn ≤80℃);2. Adjust discharge speed to ensure complete tempering;3. Tighten equipment bolts and install shock absorbers (reduce vibration)

 

　　VI. Southwest China-Specific High-Frequency Faults (Caused by Climate/Environment)

　　Due to Southwest China’s characteristics (rainy and humid weather, hilly/mountainous terrain, abundant biomass resources), the following faults occur significantly more frequently than in other regions and require focused prevention:

　　1. Equipment Rust/Electrical Short Circuit

　　Manifestations: Rust on bins and frames; control cabinet tripping and component burnout.

　　Causes: Rainy and humid weather; outdoor placement or poor ventilation of equipment.

　　Solutions:

　　Elevate the equipment base (avoid ground moisture erosion); derust and repaint bins semi-annually.

　　Install dehumidifiers/desiccants in control cabinets and rain shields for electrical components.

　　Open bin doors and inspection ports for ventilation after operation (2-3 hours on sunny days).

　　2. Biomass Fuel Caking/Blockage

　　Manifestations: Blocked feed inlet of biomass combustion furnaces; failure to ignite.

　　Causes: Rainy weather in Southwest China causes biomass pellet caking (moisture >15%).

　　Solutions:

　　Store fuel in a dry and ventilated warehouse (elevate the base and lay moisture-proof cloth).

　　Install vibrating screens at feed inlets (filter caked fuel) and clean feed channels daily after operation.

　　3. Mobile Dryer Travel Faults

　　Manifestations: Tire leaks, brake failure, loose traction devices.

　　Causes: Bumpy mountain roads cause severe tire wear; brake system moisture.

 

　　Solutions:

　　Check tire pressure and brake performance before operation (mandatory for mountain operations).

　　Regularly tighten traction device bolts and apply anti-rust oil to the brake system (avoid moisture-induced rust).

 

　　VII. Core Principles of Fault Prevention (Reduce Failure Rate by 80%)

　　Daily Maintenance: Clean residual grain and dust daily; inspect fuel supply and electrical wiring.

　　Regular Upkeep: Conduct lubrication, calibration, and wearing part replacement at 50/200/500-hour cycles.

　　Standardized Operation: Avoid overload; do not arbitrarily increase hot air temperature; set parameters according to grain types.

　　Environmental Adaptation: Strengthen moisture prevention in rainy seasons; ensure equipment fixation and driving safety for mountain operations.

　　Fault Logging: Record fault time, causes, and solutions for future traceability.

Keywords： What are the Common Faults of Grain Dryers?

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