Reducing Solvent Emissions in Automotive Spray Painting

Abstract

The body of information presented in this paper is directed to those individuals concerned with reducing solvent emissions from paint spray booths and associated ovens to meet the control limit of 3000 pounds per day per source mandated in several states. Engineering studies of spray booths and ovens have shown that unacceptable costs and energy usage would be incurred by the use of any known "add-on" of equipment to treat the large volumes of air currently discharged containing low levels of solvent. It was hypothesized and subsequently proved that a solvent emission profile exists along the length of typical spray booths and ovens. This suggested that selective collection of exhaust from solvent-rich zones and discard of exhaust from solvent-lean zones could reduce air volumes requiring abatement. By maximizing use of automatic painting, reducing booth length, avoiding longitudinal intermixing between manual and automatic painting zones, and staging of solvent-laden air exhausted from manual zones through automatic zones, it has been demonstrated on a commercial automotive production fine that only near 10% of the currently discharged air needs to be treated to meet this 3000 lb/day limitation/source. For such reduced volumes, the investment for emission reduction is more acceptable. Moreover, the hot gases emitted after abatement, such as in an incineration system equipped for heat exchange, can be used as an energy source. The reduction in fuel for booth air heating resulting from reduced booth air usage, coupled with heat from solvent combustion, should provide nearly a 35 % reduction in fuel energy requirements for the automotive color area.