Cost-Effective Emission Management and Ventilation of Large Aircraft Painting Facilities: Oxidation of Toluene and of MEK Adsorbed to Irradiated Hopcalite
Abstract
In many AF aircraft painting operations the use (and cost to use) ventilation air is excessive. Reluctance to recirculate filtered ventilation air, coupled with overcompliance with ventilation rate standards in 29 CFR 1910.94(c)(6)(ii) exaggerates energy costs by as much as a factor of 10; for low-observable coatings, the savings in HVAC costs can be significant. Further, treatment to remove contaminants in the recirculating circuit is not an exhaust emission treatment, so such treatment should comprise a source reduction strategy. In 1992 Seymour Johnson AFB, North Carolina, applied these concepts in designing a recirculating hangar whose process for decontamination of the recirculated air was base on an alleged room-temperature catalyst, hopcalite that had earlier been exposed to e-beam radiation. After a year in service, samples of recovered catalyst were found to exhibit no discriminable activity in room-temperature tests at EPA and at AFRL, but heating of a solvent-saturated sample produced rapid oxidation at ^190 deg C. Extrapolation of the estimated half-life for reaction at ^190 deg C to 20 deg C predicted a half-life for reaction of the solvent in days, which created a possibility that oxidative recovery occurs too slowly to observe easily. Long-term tests with toluene and MEK are described, and the experimental results of these tests eliminate the possibility of such a slow recovery process, indicating that the "activation" treatment afforded no more than temporary enhancement of catalytic activity. However, the failure of the specific control installed does not invalidate the concept of inserting a VOC-removal device into the recirculating ventilation stream as a process element to lower concentrations inside the workspace-or the collateral benefit of reducing the magnitude of the emission source--and further pursuit of such designs is strongly encouraged as an energy-saving measure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2003
- Accession Number
- ADA419072
Entities
People
- Joseph D. Wander
- Josh L. Scott
- Marilyn M. Barger
- R. K. Crowe
Organizations
- Air Force Research Laboratory