Size Reduction: Shredder or Chipper ?

There are many biomass processings that require size reduction. With this size reduction, the biomass raw material has a smaller and more uniform size and shape, making the follow-up process easier. After reducing the size, the surface area or contact area becomes larger so that the drying process will be more efficient, especially in continuous drying. The small and uniform size also makes handling easier. Size reduction is usually used in the initial / pretreatment process before the main / core process of processing a biomass.

Biomass, especially from plants, also has various shapes and sizes. This greatly influences the size reduction equipment used. Fibrous biomass such as coconut fiber or empty oil palm fruit bunches will be more effectively and efficiently reduced in size with a shredder rather than a chipper. This is because the fiber dominant and tenacious structure is easier to tear or shred and crush than to cut into pieces like using a knife.

Meanwhile, woody biomass has hard, brittle characteristics and an elongated shape, so the use of a chipper is more effective and efficient compared to a shredder. The character of the wood is easier to cut with equipment such as a knife for size reduction. The output or product from the shredder and chipper is also different in terms of size and shape. The wood produced from the chipper machine is usually called wood chips and looks like chopped wood, while the output from the shredder is in the form of shreds.

Biomass processing products into energy, namely by compaction (densification) into pellets or briquettes, as well as thermochemical routes such as pyrolysis, gasification and combustion are widely used today. If the size and shape of the biomass from the size reduction equipment is suitable, it can be used immediately. However, if the shape and size are not suitable then it is necessary to continue with the next size reduction stage, namely using a hammer mill so that a biomass product is obtained that can be the size of sawdust. In the production of pellets and briquettes, the biomass particle size needs to be made as small as the sawdust, so that compaction (densification) is optimal. Meanwhile, in the thermochemical process, the size of the biomass becomes small particles such as sawdust, usually for equipment that carries out fluidization, for example fluidized bed combustion.