Promoted Ignition-Combustion Tests with Structured Aluminum Packings in Gaseous Oxygen with Argon or Nitrogen Dilution at 0.1 and 0.6 MPa Available to Purchase

High-surface-area aluminum structured packings are finding a wide use in the cryogenic distillation of air. An experimental program was performed to determine the oxygen compatibility of commercial packings. In particular, the influence of pressure increase up to 0.6 MPa (6 bar absolute) and the effect of the replacement of nitrogen by argon as O₂-diluting gas were investigated. Additionally, the impact of reducing the sheet thickness from 0.2 mm to 0.1 mm was tested.

The packing samples weighing 120–250 g were ignited on top by a 3 g thermite pill, resulting in a combustion channel which was either contained within the sample or passed through it. Incidents causing a noticeable downward widening of the channels were evaluated as “promoted combustion.” Typically, a promoted combustion occurred when the weight loss of corrugated sheet exceeded 10%.

The increase of pressure reduces the O₂-threshold concentration for propagated combustion, as expected. Reducing the thickness of the sheets from 0.2 mm to 0.1 mm affects the O₂-threshold concentration only slightly. A replacement of N₂ by Ar as O₂-diluting gas at 0.6 MPa shifts the O₂-threshold somewhat beyond accuracy, but the extent of combustion in O₂/N₂-mixtures is much more substantial than in O₂/Ar-mixtures. Thus a complete destruction of the Al-samples is reached in O₂/N₂-mixtures at much lower O₂-concentrations.