Cistus ladanifer solar drying, milling and pelletizing - sawdust particle distribution and its influence on pellets quality
Diana Almeida1; Edmundo Marques2; João Monney Paiva1
1 Politécnico de Viseu; 2 Universidade do Porto
doi:10.20906/CPS/COB-2015-1368
Resumo
Cistus ladanifer also known as rockrose, referred on literature by its use in the perfumery and cosmetic industry was used in this work for pellet production aiming to study the energy requirements to obtain high quality Cistus ladanifer pellets. This study verifies the influence of particle distribution and burnet particles on further pellet quality. Initially, solar drying process was studied, in a solar kiln previously instrumented with appropriate sensors, data loggers and software to record real time solar radiation, temperature and air relative humidity data. Also, a device was used to monitor sample's water content loss. Eleven days drying cycles were carried out and variables related to the drying process calculated. As the drying process occurred a decrease on the drying efficiency and an increase on the energy needed was registered. Milling and pelletizing machines were also previously instrumented to monitor manufacturing conditions. In general, pellets produced presented dimension values acceptable as established by EN 14961-2. Concerning durability and water resistance, the best results obtained (representing high quality pellets for commercialization) were respectively 98.7 and 28.9%, respectively, after adding Cistus ladanifer sawdust with mean particle diameters of 716 µm and a moisture content (in wet basis) of 13.7%. Pellets produced with forest fire burned raw material presented a durability of 74.6% and negligible water resistance (they practically disintegrate as they have acquired significant hygroscopic characteristics). An energy balance was made. Finally, higher incidence of finer particles with wider distributions increases pellet's quality.
Palavras-chave: Cistus ladanifer ; solar drying; pelletization ; particle distribution; pellet quality