Variations in Properties and Pelletization of Camellia oleifera Shell During Five-Month Storage

Camellia oleifera shell (COS) is a prominent byproduct in woody oil processing, which is produced in a large quantity. This study delves into the impact of storage time and storage atmospheres (oxidative and anoxic) on physicochemical properties and pelletization behavior of COS during a five-month storage in an industrial scale. After five months storage, the hemicellulose content decreased (from 36.51 to 32.65%) and the lignin content increased (from 15.21 to 16.84%). The fuel value index (FVI) of COS showed an upward trend after storage, in which the oxidative area represented by S1 increased from 98.36 to 182.83, and the anoxic area represented by S4 increased from 98.36 to 153.15. This is mainly related to the continuous decline of moisture content during storage. Short-term storage can improve the combustion characteristics of COS, and anoxic storage demonstrated superior combustion characteristics and combustion stability compared to oxidative storage. The compaction energy consumption of COS initially increased and then decreased after storage. In S1 (top of the storage pile, oxidative atmosphere), it rose from 16.96 to 20.70 kJ/kg before declining to 15.44 kJ/kg. Similarly, S4 (bottom of the storage pile, anoxic atmosphere) increased from 20.78 to 22.59 kJ/kg before dropping to 15.58 kJ/kg. After storage, the lignin content of COS was relatively increased, thereby enhancing the plasticity of COS and reducing the compaction energy consumption. These findings suggest that oxidative storage may be preferable for enhancing the overall pellet quality of COS, while anoxic storage might have a detrimental effect. Therefore, during industrial storage, minimizing anoxic areas within storage piles may be beneficial.