Prevention of self-ignition in biomass storages (HOSEP)

Projektnummer 359

As reported by the members of the EWG Biomass self-ignition of biomass storages is a permanent problem.

Storing biomass leads to qualitative and quantitative losses by microbiological activity. An unknown chemical reaction, which may possibly be catalyzed by microbiological products, can lead to a self-heating and even self-ignition of biomass heaps.

The objective of the project is to investigate the procedures in biomass storages, in particular the correlation between humidity, temperature, microbiological and chemical activity. Due to successful investigations, process engineering strategies will be derived, which contribute to a safe, low-loss storage and the prevention of self-ignition.

Moisture content and temperature will be measured at defined positions in heaps of wood chips. Samples will be taken for microbiological analyses. Parallel to the outdoor trials, wood chips will be exposed to similar conditions in a test chamber (Self-Ignition Box, SIB). Pressure and thermal isolation caused by above lying biomass can be simulated in the SIB. The volume allows gas exchange by diffusion. At the SIB the partial pressure of oxygen, carbon dioxide and carbon monoxide can be measured, which leads to conclusions on the metabolic activity of the microorganisms and incomplete oxidation processes.

The project will be carried out over one year to compensate seasonal fluctuations for the outdoor trials. Every single experiment will take one month. The results of each experiment will be analysed and used to adjust the next experiment.

The results of this work will be part of the VGB-Standard „Protection against Fire and Explosion in Biomass Power Plants”.

The project is supervised by the VGB-European Working Group “Biomass”.