(48c) Hydrocarbon Haze and Asu Safety

This paper summarizes atmospheric haze, its potential impact on Air Separation Unit (ASU) safety, and some methods to reduce the safety risks.

Haze occurs when small particles and gases in the atmosphere reduce visibility by absorbing and/or scattering light. Haze can be characterized based on the source as

? Biomass Fire Haze (BFH)

? Urban Air Pollution (UAP)

? Rural Air Pollution (RAP)

? Industrial air Pollution (IAP)

All hazes contain some carbon, in both organic and elemental forms. These combustible particles are a potential ASU safety problem because they can potentially enter the process, collect in high purity liquid oxygen and can react explosively. The particle size, composition and concentration in the atmosphere determine the actual risk. The source affects the particle size and composition, and typical values are presented.

In the past decade, BFH from widespread forest fires has become a concern for ASU safety. This paper surveys some past forest fires, including the large ones in Southeast Asia that occurred in the El Nino years of 1997-98.

There are some design and operating features that may be used to mitigate the haze hazard to an ASU. Included is a simple, approximate method for estimating the BFH concentration from visibility.