A Chicago, Illinois, spray coater needed to comply with federal EPA new source performance standards and EPA Title V air regulations. The company established the Spray Coating Air Pollution Compliance Project to help it determine how to deal with regulations. The project was headed by Controlled Environmental Systems (CES), Waukesha, Wisconsin.
CES suggested a Retox twin-bed regenerative thermal oxidation (RTO) system. This system, from Adwest Technologies, has a compact modular design and low operating costs. The 10,000-scfm RTO system accommodates hydrocarbon VOCs for two tandem spray coating booths. The system operates energy free and is self-sufficient at solvent loadings of 420 ppmv and greater.
The spray booths use a variety of solvent blends in the spray coating formulations, including MEK, xylene, toluene, alcohols and heptane. The RTO has an AC variable frequency drive with pressure control capability that saves fan electrical energy when only one spray booth is on line.
The RTO system provides 99-pct hydrocarbon removal, which meets and exceeds current air quality standards and regulations for the spray coating industry.
Since installation, the system has operated continuously with no maintenance required. It provides rapid startup of less than an hour from a cold start, which allows for almost instant startup after a weekend shutdown.
The spray painting shop is quite efficient, installing RTO insulation to allow the oxidizer to store and retain the heat of combustion for a longer time.
The RTO system provided the lowest life cycle project costs when factoring in the capital, energy use and maintenance costs. This simplified the selection process for the team. The system features a PLC control system that is equipped with an integral Tel-Max telemetry package for on-line service diagnostics and record keeping of the unit's operation.
The system was installed in a converted loading dock area. This saved the paint shop floor space that is devoted to coating electronic components. This allowed the coater to achieve and exceed VOC compliance on a budget.