To reinforce control of the manufacturing processes of vinyl chloride and polyvinyl chloride (PVC) and to reduce vinyl chloride monomer (VCM) emissions, the EPA promulgated the Air Pollutant Emission Standards for Manufacturing Vinyl Chloride and Polyvinyl Chloride on 22 January 2019.
VCM is a hazardous air pollutant (HAP) known to be a human carcinogen. To lessen the negative impacts on the environment and human health caused by exposure to this gaseous substance, the EPA is tightening the emission standards for VCM produced by the petrochemical industry.
Forming comprehensive control regulations for better air quality
The existing Volatile Organic Compound Air Pollution Controls and Emission Standards regulates major emission sources such as exhaust gas combustion towers, storage facilities and equipment components. The volatile organic compound (VOC) emission standards have led to significant VOC reduction outcomes; hence, the EPA is now further advancing controls on HAPs emitted by the petrochemical industry by applying stricter VCM emission control standards.
Achieving emission reductions with the best available control technology
After taking international regulations and control implementation experiences into account, the EPA also re-evaluated its existing air-pollutant emission control policies before formulating the new standards. Based on assessments of potential health risks and the capacity of control equipment and technology in Taiwan, the Air Pollutant Emission Standards for Manufacturing Vinyl Chloride and Polyvinyl Chloride were designed to strengthen the control of the manufacturing, storage, and transport of vinyl chloride and PVC. By tightening the control standards, the EPA aims to reduce the adverse effects caused by HAP emissions (e.g., VCM and dichloroethane) discharged from factory exhaust pipes or escaped from facilities.
Strengthening industrial participation
The main focus of the new standards includes:
．Limiting vinyl chloride emissions from exhaust pipes to no higher than 10 ppm
．The screening value of VOC emissions from each individual equipment component shall not exceed 1,000 ppm. To prevent leakage and enhance source control, facilities are also required to install leak prevention components.
．Leak control connectors are to be installed to all loading and unloading lines and kept closed when not in use to prevent leakage during the loading and unloading operation process.
．Storage vehicles are required to maintain all components and loading and unloading lines sealed, in which condition the VOC concentration does not exceed 1,000 ppm.
．The VOC emission concentration is not to exceed 500 ppm during the operation of a polymerization reaction to avoid excessive pollutant emissions.
．VCM manufacturers with fixed-roof tanks for dichloroethane storage are to be equipped with pressure/vacuum vents that are connected to pollution control systems with an emission reduction rate of 95% or higher.
．Multiple wastewater control measures for VCM and PVC plants have been added to the emission standards. To prevent pollution caused by VCM emissions from process and fugitive sources, PVC plants are requested to treat their wastewater until its content of VCM concentration is below 0.1 mg/L, before recycling and reuse.
The implementation timeline for the standards will provide sufficient time for adjustments. Except for certain improvement works that are granted an extra one to three years for completion, the rest of the regulations will take immediate effect as of the date of promulgation.
Excerpt from Environmental Policy Monthly, 22(2)
- Environmental Protection Administration, R.O.C.(Taiwan)