Characterization of self-heating in stored waste

Abstract

A common cause of fires in large bulk storages is spontaneous combustion. This project aimed at creating a general test procedure and an evaluation methodology to obtain relevant risk parameters for different types of waste with respect to self-heating characteristics and the risk of spontaneous combustion. SLF (Shredder Light Fraction) from shredding of automobiles has been used as a pilot waste. The methodology is aiming at being used by e.g. the waste management sector in order to examine the propensity to self-heating of a specific waste fraction. Based on such characterization, storage could be better planned to avoid fires. The work of the project showed that with a combination of a relatively large scale test method (1 m³), and isothermal calorimetry one can study both how a material behaves regarding self-heating in bulk form and how the various constituent components affect self-heating. This means that these methods can give an indication on the cause of a specific fire, on which components of a given waste contribute to the self-heating, on how a particular mixture behaves in relationships to another, etc. In summary the developed methodology involves: 1) Representative sampling and characterization of the waste including grinding of subsamples for analysis by laboratory methods, 2) Analysis of heat generation from self-heating by isothermal calorimetry, 3) Determination of thermal properties of the waste bulk material by using a small-scale test method (TPS) for the heat capacity and for the effective thermal conductivity, 4) Large scale self-heating tests with the waste in its original fraction to provide information on critical temperatures for varying storage conditions.