Cooling Process in Wood Pellet Production
Necessity of Wood Pellet Cooling Process
After the pelletizing process, the temperature of wood pellets is between 60-80 degrees and the moisture content is close to 15%. At this moment, packing these pellets right away is not recommendable. The hot, soft and plastic pellets are easy to generate steam.
Besides, the moist pellets are easy to break into powder without cooling. So a pellet cooler must be used to reduce their surface temperature and the moisture content, which prevents the pellets from condensation and mildew, makes the wood pellets easy to transport and store, meanwhile helps screen good and pure pellets.
The Effect of Wood Pellet Cooling
Cooling procedure improves pellet durability and reduces dust accumulation during the transportation and storage of the end products. Counter flow cooler is a cooling type that common used in wood pellet industry currently, which works on the principle of counter current heating exchanging. Besides, almost all coolers have the function of separating the fines or dust from the rest of acceptable quality product. The separated dust and fines are recycled in the pellet mill so as to minimize the biomass losses and increase the conversion rate of biomass to pellets. Cooling can improve the pellet quality, reduce cracks in the pellet surface and reduce the amount of fines.
To achieve the required cooling effect, pressure and volumetric flow rate of air, length of column along with the residence time will play a crucial role. It includes intake air lock, cooling chamber, grid gate, blower, and pipeline and cyclone assembly.
Why Choose the Counter Flow Cooler?
Counter flow cooler is not the only type of cooler that we can choose to cool the pellets. But why we choose the counter flow cooler?
1. Counter flow cooler is high efficiency. After cooling, the temperature of cooled pellets would be lower than the room temperature 3 to 5 centigrade and the moisture will be removed by 3.5%.
2. Counter flow cooler discharges automatically. The unique sliding-valve discharging unit also ensures it running stably and discharge smooth.
3. The rotating material sprinkle device ensures material be cooled equably and drastically; the countercurrent cooling method avoids direct blowing of cool air on the hot pellets, which prevents surface cracking of the pellets, maintaining high pellet quality.
4. The series counter flow coolers can match with secondary volute separator for combination use. And can be used to cool down all kinds of pellets.