The use of biomass pellets is increasing. As a consequence, large indoor storage facilities are needed along the transportation chain. The increased production volumes, transportation, handling and storage of pellets result in increased risks. A number of fire incidents due to spontaneous ignition in wood pellets have been reported. Increased efforts concerning safety and quality assurance are, therefore, important. The aim of present work is to provide methods for estimating risks for self-heating from pellets stored in bulk quantities. This report compares medium scale tests of pellets in bulk with smaller screening test; micro calorimeter and crossing point. Two types of pellets; one “reactive” and one “less reactive” were compared. Kinetic parameters from the crossing point and micro calorimeter tests was used as input data for Frank-Kamenetskii calculations and compared with the medium scale test results. Calculations of the critical ambient temperature and time to self-ignition have also been preformed on four different types of representative types of full scale storages that either exist today or might be possible in the future.
The results clearly reveal that results in medium scale can be predicted by using results from small scale screening methods like isothermal calorimetry or crossing point. The small scale test methods show the same indications as medium scale when comparing reactive and less active pellet types.
The medium-scale tests were effective in separating the self-heating activity of the two types of pellets investigated.