MEMORANDUM


DATE:		February 15, 2019 

SUBJECT:	Proposed Requirement for Periodic Testing of Emission Capture Systems and Control Devices

FROM:		Barrett Parker, OAQPS/SPPD/MPG
            Paula Hirtz, OAQPS/SPPD/MMG

TO:			Surface Coating of Metal Cans and Metal Coil Dockets

      As part of an ongoing effort to improve compliance with various federal air emission regulations, the EPA reviewed the testing and monitoring requirements of the National Emission Standards for Hazardous Air Pollutants (NESHAP) for the Surface Coating of Metal Cans, 40 CFR part 63, Subpart KKKK (Metal Cans) and the Surface Coating of Metal Coil, 40 CFR part 63, Subpart SSSS (Metal Coil). 
      
      The Metal Cans and Metal Coil NESHAP provide owners or operators with several options for demonstrating compliance with hazardous air pollutant (HAP) emission limits, including the use of compliant coatings, i.e., coatings with formulations meeting the NESHAP emission limits. Capture or add-on control devices are not needed for processes using these compliant coatings. 
      
      If compliant coatings are not used, owners or operators have the option of using capture and add-on devices to demonstrate compliance, as listed in Table 4 of the Metal Cans NESHAP and Table 1 of the Metal Coil NESHAP. Such add-on HAP control devices include those associated with combustion (i.e., thermal oxidizers, regenerative oxidizers, and catalytic oxidizers), and recovery (i.e., carbon adsorbers, condensers, and concentrators (including absorbers)).   To demonstrate compliance with the HAP destruction or removal efficiencies required by the NESHAP, owners or operators choosing to use add-on control devices are also required to demonstrate 100 percent capture efficiency of the HAP-laden exhaust streams.
      
      Currently, the Metal Cans and Metal Coil NESHAP require owners or operators who choose to use capture and add-on control devices to comply with the rules to conduct a one-time initial performance test to demonstrate the destruction or removal efficiency test of the control device coupled with capture efficiency testing. No additional performance tests are required by the NESHAP; instead the NESHAP require the ongoing monitoring of operating parameters. The operating parameters to be monitored are identified during the one-time initial performance test (when the capture system and control device efficiencies are measured). In addition, the range of the operating parameters, typically associated with temperature or flow or both, is established during the initial testing. As long as the initial performance test demonstrates the NESHAP required capture and HAP destruction/recovery efficiencies, then operation in accordance with the operating parameters established at that time is accepted as ongoing compliance with HAP emission limits. 
      Although ongoing monitoring of operating parameters is required by the NESHAP and is conducted by owners or operators, as the control device ages over time, the destruction efficiency of the control device can be compromised due to various factors. The EPA published several documents that identify potential control device operational problems that could decrease emission reduction efficiency, including, but not limited to: corrosion due to halogens in HAP exhaust for thermal oxidizers, catalyst deactivation or poisoning for catalytic oxidizers, leaking valves for regenerative oxidizers, adsorbent plugging and fouling for adsorbers, and changing waste stream temperatures and absorption characteristics for condensers and concentrators (see Control Technologies for Hazardous Air Pollutants, EPA/625/6-91/014, June 1991, available at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey =30004CRL.PDF; Control Technologies for Volatile Organic Compound Emissions from Stationary Sources, EPA 453/R-92-018, December 1992, available at https://nepis.epa.gov/ Exe/ZyPDF.cgi?Dockey=2000HI7Q.PDF; and Survey of Control Technologies for Low Concentration Organic Vapor Gas Streams, EPA-456/R-95-003, May 1995, available at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=2000F17T.PDF). 
      The Institute of Clean Air Companies (ICAC), an industry trade group currently representing 50 emission control device equipment manufacturers, corroborated the fact that control equipment degrades over time in their comments in a prior rulemaking. In their comments, ICAC included information about potential control device operational problems and case histories in which control device degradation or failure led to CAA violations and enforcement actions. ICAC also stated that emissions control systems are complex, consisting of chemical, electrical, and mechanical devices that can fail in each of these component areas, if not adequately maintained. ICAC discussed the causes of degradation for devices commonly used for HAP control, providing examples for thermal and catalytic oxidizers. ICAC stated that extreme operating temperatures, the corrosive nature of chemical-laden air, exposure to weather, and the wear and tear of non-stop use affects thermal oxidizers such that, left unchecked, the corrosive nature of the HAP-laden gases will create equipment downtime, loss of operational efficiency, and eventual failure of the thermal oxidizer. Moreover, ICAC stated that catalysts from catalytic oxidizers need to be checked periodically to verify the activity of the catalyst because the overall ability of the catalyst to convert target emissions to other by-products will naturally diminish over time. 
      
      Routine maintenance checks and preventative maintenance procedures are specified by the equipment manufacturers to maintain optimal performance of the control device. These procedures are required to be conducted weekly, monthly, semi-annually, and annually and include all components of the control device. ICAC stated that it is more expensive to operate an oxidizer at optimal performance, and if not maintained, performance will deteriorate yielding less destruction of HAP. ICAC also stated that maintenance of the electrical components ensures the combustion temperature, and therefore, the destruction efficiency, is maintained. ICAC also stated that mechanically, failure of a fan bearing, a burner, or a heat exchanger would result in higher emission levels.
      
      Operational changes after the initial performance test also may affect the destruction efficiency of the control device. These changes include but are not limited to: ongoing reformulation of coatings that change the chemistry of the flue gases; changes in production capacity (i.e., addition, expansion, redistribution, or removal of coating lines); switching of fuels; and improper maintenance leading to the gradual degradation of the capture and/or control device.
      
      The EPA also recently reviewed emission violations in Ohio and Massachusetts by owners and operators of sources that did not achieve compliance even though they maintained the operating parameter values (in these cases, thermal oxidizer operating temperatures) that were established during previous performance tests. As shown in Table 1 below, subsequent performance tests resulted in diminished emission reduction efficiencies, possibly as a result of control device degradation due to elevated temperatures and/or other factors identified above.
      
Table 1  -  Facilities in Ohio and Mass that Met Previously-set Temperature Limits but Failed to Meet Destruction Efficiency (DE) Requirements
                                    Source
                                Control Device
                         Average Oxidizer Temp (ºF) 
                                Required DE (%)
                          DE measured during Test (%)
A (Ohio)
                               Thermal oxidizer
                                     1540
                                      95
                                     88.4
A (Ohio)
                               Thermal oxidizer
                                     1572
                                      95
                                     49.3
B (Ohio)
                               Thermal oxidizer
                                     1537
                                      98
                                      63
C (Ohio)
                               Thermal oxidizer
                                     1326
                                      90
                                     87.7
D (Massachusetts)
                               Thermal oxidizer
                                     1500
                                      98
                                      96
      
      As a result of these findings and in order to improve compliance with the Metal Can and Metal Coil NESHAP, the EPA proposes to require owners or operators who choose to demonstrate facility compliance with the standards by using emission capture systems and add-on controls to conduct periodic air emissions performance testing, with the first of the periodic performance tests to be conducted within 3 years of the effective date of the revised standards and thereafter no longer than 5 years following the previous performance test. The 5-year period corresponds to the renewal period for title V air operating permits required under 40 CFR part 70 or 71. 
       
      We recognize that ongoing periodic performance tests are already required by some state and local permitting authorities for facilities subject to these regulations. These state and local requirements satisfy the NESHAP requirements as long as the performance tests are conducted at least every 5 years. The addition of a periodic performance testing requirement to these federal regulations will require all facility owners or operators to conduct periodic testing, reestablish operating limits if needed, and ensure that capture and control systems are properly maintained over time, thereby reducing the potential for acute emissions episodes or non-compliance. The EPA expects periodic testing of the actual destruction efficiency (versus the monitoring of operating parameters) could result in the increase of the operating temperature to compensate for oxidizer inefficiency, or if the required destruction efficiency cannot be achieved, additional oxidizer maintenance will be conducted, supplemental control will be installed, or replacement of the oxidizer will be required.
