Other Pellet Applications
Sugarcane bagasse is used as a fuel in sugar mills; and with its low density, the thermal efficiency is extremely low. If bagasse is free of silica and contaminates it can be pelleted. Pelletizing bagasse has many advantages. These advantages include: easy storage; eliminates the chance of spontaneous combustion; and improves the density, durability and the combustion performance of this fuel type.
Bagasse is made up of 18.6% lignin. This lignin acts as a natural glue during the manufacturing process. When the temperature of the bagasse reaches 120-160 degree centigrade, the sugars in the bagasse dissolve. With a temperature of 180 degree centigrade, lignin softens and plasticizes. At this time, the lignin of the sugarcane bagasse can glue the fibers together under a certain pressure range.
Fresh wet sugarcane bagasse normally contains approximately 60-70 percent moisture. For the further utilization of this fuel, it’s moisture content must be reduced to approximately 10%. If this moisture is not reduced, the redundant moisture will evaporate during the high temperature extrusion process, and the steam may cause the surface of the bagasse pellet to crack.
Burning agricultural waste and crop residues may be an easy way to create heat and power, however it is certainly not an economical option as the fibrous material is low in bulk density, is difficult to handle, and is expensive to transport. When stored it is also prone to spontaneous combustion.
The reduction is sizing of the fibrous material and dealing with the cellouse content in the material can be challenging, however, by choosing the correct reduction process and die relief, agricultural waste can be successfully pelleted as it is usually high in natural starch. Once pelleted, agricultural pellets can also be stored for lengthy periods.