When using the straw pelletizer to produce biomass fuel pellets, improper operation or insufficient detail control can lead to decreased pellet quality, increased equipment wear, and even production interruption. Here are the three core issues that need to be focused on and the corresponding solutions:
1. Control of raw material moisture content: The "critical threshold" affecting the molding effect
Problem manifestation:
When the raw material moisture content is too high (>20%), the pellets are prone to stick to the mold, resulting in "soft collapse" and easy mold growth after cooling; when the moisture content is too low (<10%), the raw material has poor mobility， and it is prone to slipping during molding， resulting in loose and easily broken pellets， and will also accelerate the wear of the mold and the roller.
Solution points：
Pre-emptively test the moisture content of the raw materials (recommended to use a moisture analyzer)， and control the moisture content of straw， wood chips， etc. to be within 12%-18% (there are slight differences for different raw materials； for straw， it is recommended to be 14%-16%， for wood chips， 12%-15%).
When the moisture content is too high， you can reduce the moisture through sun-drying or drying equipment (such as drum dryers)； when it is too low， you can appropriately spray moisture (need to spray evenly to avoid local over-hydration).
Pay attention to moisture prevention of the raw material storage environment， especially during rainy days， it should be sealed storage to avoid secondary moisture absorption of the raw materials.
2. Matching of molds and rollers and maintenance of wear： Determining the pellet molding efficiency and lifespan
Problem manifestation：
If the mold hole diameter does not match the characteristics of the raw material (such as coarse fiber raw materials using a fine hole diameter mold)， it will lead to blockage， difficulty in pellet production； if the gap between the roller and the mold is too large， the raw material cannot be effectively compressed， resulting in low pellet density； if the gap is too small， it will intensify the friction between the two， shorten the service life， and even cause "machine jamming". In addition， over time， the mold holes are prone to be clogged with impurities and the surface of the roller is worn， resulting in a sudden drop in pellet production rate.
Solution points：
Mold selection： Choose the mold hole diameter based on the hardness and fiber length of the raw material. Coarse fiber straw (such as corn straw) is suitable for a 8-10mm hole diameter mold， fine wood chips are suitable for a 6-8mm hole diameter mold， avoiding "small horse pulling a big cart".
Gap adjustment： After new equipment or mold / roller replacement， adjust the gap to 0.1-0.3mm (measured with a feeler gauge) to ensure that the roller and mold surface are slightly in contact without rigid friction.
Regular maintenance： Every 8-12 hours， clean the residual materials in the mold hole (use a dedicated cleaning needle)； check the wear of the roller every week. If there are grooves or unevenness on the surface， repair or replace it in time； after 100-200 hours of use， you can flip the mold for use (some molds support bidirectional use)， to extend the service life.
3. Coordinated operation parameters and feeding speed of the equipment： Avoid overload and fluctuation in pellet quality
Problem manifestation：
If the feeding speed is too fast， exceeding the processing capacity of the equipment， it will cause the raw materials to accumulate in the pellet machine cavity， resulting in a sudden increase in temperature (local can reach over 200°C)， causing pellet carbonization， mold blockage， and even motor overload and burnout； if the feeding speed is too slow， the raw materials are insufficiently filled， the roller is idle， resulting in low pellet density and reduced output. In addition， the parameters of the main shaft rotation speed， ring mold linear speed， etc. do not match the raw materials， which will also affect the stability of pellet molding.
Solution points：
Feed control： Control the feeding volume by adjusting the frequency of the feeder (variable speed motor)， ensuring that the raw materials enter the straw pellet machine cavity evenly. Observe the pellet output condition： if the pellet surface is smooth， without cracks， and the equipment has no abnormal noise， it indicates that the feeding speed is appropriate； if there are "broken pellets" or "frayed edges"， reduce the feeding speed.
Parameter matching： Adjust the main shaft rotation speed according to the hardness of the raw materials (hard materials such as cotton stalks can be appropriately reduced to reduce wear； soft materials such as wheat straw can be increased to improve output)； the linear speed of the ring mold is generally controlled at 2.5-6m/s (refer to the equipment manual for specific details).
Overload protection: Ensure that the equipment is equipped with an overload protection device (such as an amperage protector). When the motor current exceeds the rated value by 10%-15%, it will automatically shut down to prevent equipment damage; operators need to monitor the ammeter and thermometer in real time and stop the machine immediately if any abnormalities are detected.
Extended reminder: Safety production cannot be ignored
In addition to the above issues, the following points should also be noted: During production, keep the workshop well-ventilated (to avoid dust accumulation and the risk of explosion); operators need to wear dust masks and gloves to prevent injury from raw material debris; regularly clean the equipment cooling holes to avoid the motor shutting down due to overheating.
Controlling these 3 core issues can not only ensure the density, strength and combustion performance of the granular fuel, but also reduce the equipment failure rate, improve production efficiency and economic benefits.