A comparison of the flammability of aluminium sieve trays and aluminium packing in air separation units

In air separation units, aluminium structured packing may be used instead of aluminium sieve trays for the cryogenic distillation of air. In previously published experiments regarding the flammability of packing in oxygen-enriched atmospheres, strong energy releases have been reported under conditions which did not correspond to realistic operating conditions.

In additional tests with packing under simulated operating conditions, no propagation of combustion was observed even with strong promoters. Therefore, the authors confirmed the compatibility of aluminium packing for use in air separation units under operating conditions.

In this paper, experiments are described to compare the flammability of aluminium sieve trays, which have been used for more than 30 years in distillation columns, with aluminium packing under similar conditions.

It was found that under similar test conditions, sieve trays as well as packing are flammable. In flammability tests, violent energy releases were observed with the strong promoter thermite; however, no differences in flammability between sieve trays and packing were noticed. Comparing the flammability of the sieve trays, in use for more than 30 years in distillation columns, with packing, it was concluded that sieve trays can be substituted by packing without any additional risks.