NOx IN THE CRYOGENIC HYDROGEN RECOVERY SECTION OF AN OLEFINS PRODUCTION UNIT.

Union Carbide has been investigating the fate and possible hazards of NO//x compounds in cryogenic gas separation equipment. It has been learned that trace amounts of NO//x in the process streams can accumulate in the equipment under certain conditions. Although mixtures of condensed NO//x and condensed hydrocarbons can be ignited with a strong ignition source, the combination does not seem to present an imminent hazard. No explosive NO//x-hydrocarbon 'gums' have been found yet, but the investigation is still continuing. We recommend that equipment which is exposed to NO//x compounds be monitored to detect accumulations and prevent possibly hazardous situations.