Self‐heating and ignition of chemically activated carbon

Abstract

Abstract Following the occurrence of fires in chemically activated carbon in transit, a study has been made of the self‐heating and ignition properties of this material. Thermal ignition theory has been applied to the results of laboratory scale self‐ignition experiments and has enabled realistic prediction of critical sizes of pile for self‐heating to ignition at ordinary ambient temperatures. However, predictions of times to ignition at ordinary temperatures are much larger than found in practice. A distinction emerges between a long‐term self‐heating process responsible for the observed ignition of the ‘weathered’ carbon and short‐term processes which probably include the establishment of moisture equilibrium with the atmosphere and which are largely completed during the standard ‘weathering’ time of 8 days. The long‐term process is not affected by this weathering but is dependent on the temperature of carbonisation and weathering at elevated temperatures (e.g. 100°C). Safe carriage of the carbon in economically worthwhile quantities is ensured by packing in polyethylene bags. These can sustain a small amount of damage with impunity.