OCR Text |
Show Once the Workgroup decided to focus on the Section 112 M A C T Standards, the process for moving forward became clear. The M A C T regulations require the setting of a Floor for existing units and new units. The Floor for existing sources is defined as the average of the best-performing 1 2 % of all sources^ EPA has defined floors in terms of control equipment, emission levels, and work practices. The Floor for new sources is the best performing single unit in the data available to the E P A Administrator. All existing units are required to achieve the Floor levels within 18 months. All new sources have to achieve the Floor for new sources. The M A C T Floor has to be based on achievable technology only. Once a M A C T Floor is set, potential above-the-floor controls have to be evaluated considering technology, cost-effectiveness, as well as environmental and socioeconomic impacts. Controls that meet these standards become the M A C T Standard that all sources have to meet within 2-5 years. In most cases, EPA has set M A C T Standards as well as M A C T Floors at higher thresholds for new sources primarily due to the significant differences in cost effectiveness. Thus setting a MACT Floor requires looking at the existing control inventory, the existing emissions inventory, and the existing work practices. Where such data is not available, the EPA and by affiliation the ICCR Workgroups have the authority to collect additional information through surveys and any other available avenues. The Workgroup concluded that both the inventory database and the emissions databases for process heaters were sufficient and representative enough for regulatory development. It should be noted that the emissions database in particular was significantly augmented with data from the PERF Combustion Byproducts Project and the API/WSPA Emissions Database. Without this data, there was little air toxics emission data available. Both of these databases will be discussed in more detail in the paper by England, et. al. A flowchart of the inventory database is presented in Figure 2. Note that a total of approximately 32,000 process heaters were initially identified. A complete and thorough review of these by the entire Process Heater Workgroup identified a total of 17,207 indirect-fired process heaters remaining for inclusion in a more thorough control evaluation. These 17000+ process heaters were further characterized by fuel type. An exhaustive analysis of these 17,000+ process heaters yielded the following conclusions: 1 While many process heaters have some combustion controls, no correlation could be found between combustion controls and H A P emissions. 2. Conditions required to produce "significant" H A P emissions (1ppb or more) are significantly outside the normal operating range. Further there are serious safety and economic disincentives for operating in this regime. 3. No add-on controls were identified that were installed on process heaters and had an impact on H A P emissions with the possible exception of some wood-fired sources. |