Influence of chipping system on chipper performance and wood chip particle size obtained from peach prunings

Many obstacles hamper the full exploitation of pruning residues for energy. Among these, harvesting is a crucial point in the development of a sustainable supply, because it greatly affects the quality of the fuel and profitability of production. In normal forestry operations, drum or disk chippers are the tools most frequently used for comminution. A new chipper has been designed which can collect different pruning residues produced under different field conditions and reduce them to a standard chip size (P45) suitable for boilers. Comminution is carried out by a double-auger on which different types of blades can be mounted. This paper compares outcomes in terms of machine performance and particle size distribution as a consequence of the use of a helical (HELK) or hoe-shaped (HSK) blade. The study was conducted on a peach plantation in Spain grown with the “open centre” or "vase" training method. Analysis of the main elements illustrated the difference between the types of blades. The HELK blade performed better in terms of coverage of area (0.52 ha h−1) and material processed (1.06 t h−1). Moreover the main fraction of the particle size (60% of the fraction 3.15 ≤ P ≤ 45 mm) reached 79.2% with the HELK compared with the 67.9% with the HSK. However, from a mechanical standpoint, the HSK blade was found to perform better in terms of ease of maintenance, though the helical blade gave better results for the collection of peach pruning residues.