The Proposed Ethylene Production NESHAP and Potential Complications with Reclaimed Water Use

Volatile Organic Compound (VOC) emissions from industrial cooling tower systems can occur due to corrosion or cracking of a heat exchanger’s internal tubing material, allowing some process fluids to mix with or become entrained in the circulating cooling water. VOCs in the process fluids may subsequently be released from the cooling water into the atmosphere when the water is exposed to air. The Ethylene Production National Emission Standard for Hazardous Air Pollutants (NESHAP) includes heat exchange or cooling tower systems as emission sources at ethylene production facilities. Under this standard, an Ethylene Production Maximum Achievable Control Technology (EMACT) identifies work practices that specify monitoring and Leak, Detection and Repair (LDAR) to control potential heat exchange system VOC air emissions. In September 2019, the EPA proposed EMACT amendments for heat exchange systems that would further reduce potential air emissions. A leak action level is to be defined using the Modified El Paso Method for Determination of VOC Emissions from Water Sources. The resultant action level is equivalent to less than 1 ppmw of strippable VOC in the return cooling water. Since the monitoring point for this proposed EMACT is only after the heat exchanger(s) in the system, organics in makeup water, such as from a reclaimed/recycled water source, are not factored in as a background concentration and would be counted toward compliance. This paper presents an analysis of the impact this proposed EMACT may have on options to use reclaimed water sources for cooling water makeup at ethylene production facilities subject to this standard.