Exploring VOC Control Options

Since refineries and chemical plants handle large quantities of volatile organic compounds (VOCs), some emissions of these compounds are likely during normal operations. Based on studies in the United States, the largest source of VOCs is from fugitive emissions from piping and other fluid handling components. VOCs also come from storage tanks, loading operations, and wastewater treatment.

VOC emissions occur broadly throughout the CPI (Table 1). The relative percentages vary depending on the specific processes employed and the type of emissions controls installed. In almost all cases, fugitive emissions are the largest source of VOCs and air toxics. Air emissions from tanks and wastewater treatment are usually smaller than those from fugitives and loading.

The most applicable and economic control system will depend on the specific emission source, the level of controls already in place, and the target emission level. Controls range from increased monitoring and maintenance frequency for valve leaks, to replacing rim seals on floating roof tanks, to installing a complete vapor control system at a loading facility. The costs can vary widely. Table 2 lists options for controlling VOC emissions.

When equipment or practices are specified in a regulation, it is often possible to substitute alternatives which are just as effective, but lower in cost. In most cases, these alternatives include the choice of equipment on an emissions source or a nearby source of the same pollutant.

More recently, emissions trading between different companies and even different pollutants has been utilized. Check with the local regulatory agency to determine if these alternatives are an option.