Temperature Measurements and Examination of Self-heating in Large Scale storage of Wood Pellets

• This paper summarizes the experimental data from a large-scale storage test performed within the European project called SafePellets. Temperature measurements were made inside a silo with a capacity of storing 3000 ton of wood pellets, from August to October in 2013. The purpose of the test was to examine the self-heating of the wood pellets, where and when it occurs, how it spreads and if it could be connected to certain events. For temperature measurements, both the temperature cables belonging to the silo temperature surveillance system and thermocouples mounted by SP at the cables and on the in/out-side walls of the silo were used. The results clearly reveal that self-heating occurs almost instantly after start of filling the silo and temperatures above 40 °C inside the pellets bulk is regular. The temperature surveillance system, which was set to give an alarm signal for high temperatures, was activated several times during the test period and temperatures exceeding 60 °C were registered at several occasions. Measurements above the pellet surface also show that this headspace temperature varies much with the outside ambient temperature and the sunlight radiation. A sunny summer’s day, the headspace temperature could easily reach above 40 °C, which will influence the pellet bulk. The project also emphasized an important problem when it comes to silo storage. The problem of temperature sensor cables inside the silo not always hanging where they are supposed to be was observed in the test and dealt with.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik -- Energisystem (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering -- Energy Systems (hsv//eng)

Keyword

pellets

biomass characteristics

oxidation

self-heating

storage

Energy- and Environmental Engineering

energi- och miljöteknik

Publication and Content Type

vet (subject category)

kon (subject category)