Purpose of the presented investigations was to identify the influence of specific surface of porous inert particles on ignition and flame propagation in combustible dust/air mixtures. It is commonly known that inert dusts are able to reduce the criticality of dust/air mixtures significantly in terms of ignitability and explosion severity. Different non-combustible materials like rock dust or chalk dust are used for dust explosion prevention. In order to assess the influence of the specific particle surface on the effectiveness of inert material, tests on the ignitability of different dust/air mixtures have been carried out. Experiments have been conducted with Lycopodium Clavatum as combustible dust. Lycopodium Clavatum was mixed with inert dusts with high and low specific surface area.
As material with high specific surface Clinoptilolith, a natural aluminosilicate, was used. Clinoptilolith was compared to ceramic beads with indifferent particle sizes. In terms of benchmarking, Clinoptilolith was also compared to different other inerting material like dry chemicals for fire extinguishing purposes. To study the influence of initial humidity on the inerting effectiveness of Clinoptilolith, the material was tested at different grades of humidity. Tests have been carried out with the Kuhner MIKE III Apparatus, the 20-L-Siwek Chamber and a Tube reactor for flame speed measurements. The experimental results were compared to CFD simulations using an OpenFOAM® model.