I. Common Causes of Non-Discharge in Biomass Pellet Mills and Solutions
1. Inappropriate Material Moisture
Too much or too little moisture in the material can clog the die orifices, causing the biomass pellet mill to fail to discharge. In this case, check the material and control the moisture content between 10% and 15%.
2. Severe Wear of Die Plate and Pressure Rollers
The die plate and pressure rollers are key components of the pellet mill and are also easily worn. Aging or malfunctioning components can also cause the mill to fail to discharge. If it's a new pellet mill, simply check which component is not working to identify the problem. If it's a pellet mill that has been used for many years, it indicates that the components are worn; replacing them will solve the problem.
3. Inappropriate Die Compression Ratio
Different materials require different compression ratio dies. Reputable manufacturers will customize dies according to customer needs from the outset, generally preventing this problem. If there is no discharge, check the die compression ratio; if it's unsuitable, replace the die.
4. High Coarse Fiber Content in Material
Pellet mills come in different models and power ratings, each with different pelleting requirements. Some pellet mills are specifically designed for pressing coarse fibers, while others are designed for pressing fine fibers. Using a small pellet mill to press coarse fiber materials can also cause pelleting problems. The solution is to contact the manufacturer and replace the pellet mill.
5. Inappropriate Distance Between Die and Pressure Roller
Biomass pellet mills form pellets by pressing the die against the pressure rollers. An inappropriate distance can also prevent proper pelleting. The solution is to adjust the distance correctly.
6. Accumulated Material Inside the Pellet Mill
After production, biomass pellet mills can accumulate residue. This unremoved residue can solidify into hard lumps during the next operation due to higher temperatures, preventing proper pelleting. The solution is to clean the inside of the pellet mill to remove the residue.
II. Common Faults and Solutions of Biomass Pellet Mills
1. Raw materials cannot enter the pelleting chamber
Causes:
(1) Conditioner blockage or feed inlet bridging.
(2) Feeder auger drive malfunction.
(3) Feeder auger blockage.
Repair methods:
(1) Clean the conditioner or feed inlet.
(2) Check the feeder auger drive and troubleshoot.
(3) Clean the material on the feeder auger.
2. Raw materials enter the pelleting chamber but pellets cannot be extruded
Causes:
(1) Die hole blockage.
(2) Too much moisture in the raw material.
(3) Excessive gap between die rollers.
(4) Severely worn feed scraper.
(5) Severely worn die rollers.
Repair methods:
(1) Remove feed from the die hole.
(2) Control the moisture content in the raw materials and steam.
(3) Readjust the die roller gap.
(4) Replace the scraper and die roller.
3. Granulator motor cannot start
Causes of failure:
(1) Material accumulation in the granulation chamber.
(2) Circuit problem.
(3) Limit switch cannot reach the control lever on the gate or door.
Repair methods:
(1) Remove accumulated material.
(2) Check the circuit and troubleshoot.
(3) Check the limit switch.
4. Noise and severe vibration
Causes of failure:
(1) Bearing is damaged.
(2) Ring die pressure roller is severely worn.
(3) The gap between the ring die and the pressure roller is too small.
(4) Foreign objects in the conditioner or feeder.
(5) The main shaft bearing is too loose.
Repair methods:
(1) Replace the bearing. (2) Replace the die roller.
(3) Adjust the die roller gap appropriately.
(4) Clean out foreign objects.
(5) Tighten the nuts to reduce clearance.
5. Unreasonable fluctuations in the load of the granulator main unit or uneven granule quality
Causes of failure:
(1) Insufficient steam supply or fluctuating pressure in the steam pipe.
(2) Unstable raw material conveying.
(3) Uneven feeding caused by wear of the deflector scraper.
Repair methods:
(1) Check the steam pipeline.
(2) Adjust the feeding speed.
(3) Replace the deflector scraper.
6. Granulator stops during operation
Causes of failure:
(1) Insufficient tension of the V-belt, causing the speed controller to activate.
(2) Inappropriate settings of the speed control instrument parameters.
(3) Partial or complete severe wear or breakage of the V-belt.
(4) Overload or impurities stuck between the pressure roller and the ring die cause the main shaft to rotate, causing the limit switch to disengage.
(5) Insufficient clamp pressure or grease on the brake disc causing slippage causes the main shaft to rotate, disengaging the limit switch.
(6) Circuit fault.
Repair methods:
(1) Readjust the V-belt tension or check the pressure value on the hydraulic system pressure gauge. If necessary, reset the pressure value (be careful during adjustment).
(2) Reset the parameters.
(3) Install a new V-belt; do not replace only a part of it.
(4) Reset the main shaft and limit switch.
(5) Reset the clamp hydraulic pressure or clean the brake disc.
(6) Check the circuit.
7. Granulator frequently clogs.
Causes of the fault:
(1) Worn deflector scraper causing uneven material distribution.
(2) Worn pressure roller.
(3) One of the pressure rollers is stuck.
(4) The deflector scraper is incorrectly installed.
(5) The feed moisture content is too high.
Repair methods:
(1) Replace with a new deflector scraper.
(2) Replace with a new pressure roller.
(3) Inspect the pressure roller.
(4) Reassemble the deflector scraper.
(5) Reduce the moisture content.
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