11/29/1994
"Aggregated" means the summation of all process vents within a process that contain VOCs.
"Annual mass emissions total" means the sum of all non-fugitive VOC emissions, evaluated before control, from a vent. Annual mass emissions may be calculated from an individual process vent or from groups of process vents by using the emission estimation equations contained in Appendix K of this regulation and then multiplying this result by the expected duration and frequency of the emission or groups of emissions over the course of a year.
"Average flow rate" means the flow rate averaged over the amount of time that VOCs are emitted during emission events. For the evaluation of average flow rate from an aggregate of sources, the average flow rate is the weighted average of the average flow rates of the emission events and their annual venting time:
Weighted Average Flow Rate =
Click here to view Image (44-1)
"Batch cycle" means a manufacturing event of an intermediate or product from start to finish in a batch process.
"Batch process" means a discontinuous process that involves the bulk movement of material through sequential manufacturing steps. Mass, temperature, concentration, and other properties of the material may vary with time and location in the process. Batch processes are typically characterized as "non-steady-state."
"Batch process train" means an equipment train that is used to produce a product or intermediate. A typical equipment train consists of equipment used for the synthesis, mixing, and purification of a material.
"Control device" means an air pollution abatement device, not a device such as a condenser that operates under reflux conditions, which is required for processing.
"Emissions before control" means the VOC emissions total prior to the application of a control device, or if no control device is used, the VOC emissions total. No credit for discharge of VOCs into wastewater shall be considered when the wastewater is further handled or processed with the potential for VOCs to be emitted to the atmosphere.
"Emission event" means a discrete venting episode that may be associated with a single unit of operation. For example, a displacement of vapor resulting from the charging of a vessel with VOCs will result in a discrete emission event that will last through the duration of the charge and will have an average flow rate equal to the rate of the charge. If the vessel is then heated, there will also be another discrete emission event resulting from the expulsion of vapor from the expansion caused by heating. Both emission events may occur in the same vessel or unit operation.
"Process" means, for the purpose of determining RACT applicability, any equipment within a contiguous area that is connected during the course of a year. "Connected" means a link between equipment, whether it is physical, such as a pipe, or whether it consists of a series of steps from which material is transferred from one unit operation to another unit operation.
"Process vent" means a point of emission from a piece of equipment within which a unit operation takes place. Typical process vents from batch processes include condenser vents, vacuum pumps, steam ejectors, and atmospheric vents from reactors and other process vessels. Relief valve discharges and equipment exhaust systems that discharge from unit operations would also be considered process vents.
"Semi-continuous operation" means an operation that is conducted in a steady-state mode but only for finite durations during the course of a year. For example, a steady-state distillation operation that functions for one month would be considered a semi-continuous operation.
"Single unit operation" means a discrete piece of equipment used in a processing step to prepare reactants, facilitate reactions, separate and purify products, or recycle materials.
"Volatility" means a physical property of materials which exhibits the following characteristics: low-volatility materials have a vapor pressure of less than or equal to 75 millimeters (mm) mercury (Hg) (3.0 inches [in] Hg) at 20 degrees Celsius (°C) (68 degrees Fahrenheit [°F]); moderate-volatility materials have a vapor pressure of greater than 75 mm Hg (3.0 in Hg) and less than or equal to 150 mm Hg (6.0 in Hg) at 20°C (68°F); and high-volatility materials have a vapor pressure of greater than 150 mm Hg (6.0 in Hg) at 20°C (68°F). To evaluate VOC volatility for single unit operations that service numerous VOCs or for processes handling multiple VOCs, the weighted average volatility can be calculated using the total amount of each VOC used in a year, and the individual component vapor pressure, as shown in the following equation:
Weighted Average Volatility =
Click here to view Image (44-2)
(44-3)
where:
FR = Calculated Flow Rate (standard cubic feet per minute [scfm])
AE = Uncontrolled Annual VOC Emissions (pounds per year [lb/yr])
An owner or operator shall compare the calculated flow rate (FR) with the actual average flow rate or the actual weighted-average flow rate determined using the procedures described in 44.3.2 of this regulation, and if FR exceeds the actual average flow rate, the owner or operator shall reduce VOC emissions by 90%.
7 Del. Admin. Code § 1124-44.0