The behaviour of oil films on structured packing under cryogenic conditions

Today structured packing is commonly applied in cryogenic air separation plants. Packing is typically characterized by a high surface-to-volume ratio. Owing to the large surface of packing in comparison to common sieve trays — provided equal amounts of oil are attached to surfaces — more organic material may be present within a low-pressure column of an air separation plant. Since an enrichment of organic material in an air separation plant or in liquid oxygen is a principal hazard, and a major accumulation of organic material magnifies this risk, experimental tests were conducted to determine whether chipping of oil at cryogenic temperatures is possible.

Tests are discussed where single sheets of a packing segment had been coated with an oil film of definite thickness. The oil-coated sheets were rinsed by moving them up and down in liquid nitrogen or in liquid oxygen. After fixed time intervals the oil content of a single sheet was determined.

It was concluded that the original oil residue on the sheets up to 250 mg m⁻² remained attached to the packing surface and no decrease of oil was found within the accuracy of the oil determination method.