Proposed boiler MACT sets aggressive emission limits

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Courtesy of Trinity Consultants

On June 4, 2010, U.S. EPA proposed National Emission Standards for Hazardous Air Pollutants (NESHAP) for industrial, commercial, and institutional boilers and process heaters at both major and area sources of hazardous air pollutants (HAP) emissions.  EPA proposed separate rules for units at major sources of HAP emissions (greater than 10 tons per year [tpy] of any single HAP and/or greater than 25 tpy of total HAP) and area sources of HAP emissions (less than 10 tpy/25 tpy). The Maximum Achievable Control Technology (MACT) standards for units at major sources are found in 40 CFR 63 Subpart DDDDD, while the Generally Available Control Technology (GACT)/MACT standards for units at area sources are found in 40 CFR 63 Subpart JJJJJJ. Once promulgated, the major source NESHAP will establish emission standards for new and existing boilers and process heaters that were previously addressed in a 2004 NESHAP that was vacated by the court in 2007.

Major Source Boiler MACT
The Major Source Boiler MACT affects boilers and process heaters that burn coal, biomass, fuel oil, natural gas, refinery gas, or other gas. EPA estimates that 13,555 existing boilers and process heaters as well as 46 predicted new units to be constructed during the next three years would be affected by the NESHAP.

Applicability
The affected source for the proposed rule is defined as the collection of existing and each new or reconstructed industrial, commercial, and institutional boilers and process heaters that do not burn solid waste at major sources of HAP emissions. The definition of solid waste is found in the Resource Conservation and Recovery Act (RCRA) regulations. A unit is classified as a new source if construction is commenced after June 4, 2010. Similarly, sources that are reconstructed (as defined in 40 CFR 63.2) after June 4, 2010 are classified as reconstructed sources. A boiler or process heater is classified as existing if it is not new or reconstructed. The compliance date for new sources is the date the final rule is published in the Federal Register or upon startup, whichever is later. The compliance date for existing sources is three years from the date the final rule is published in the Federal Register. The following units are exempt from the requirements of the rule:

  • An electric utility steam generating unit (> 25MW)
  • A recovery boiler or furnace covered by 40 CFR Part 63, Subpart MM
  • A boiler or process heater that is used specifically for research and development; this does not include units that provide heat or steam to a process at a research and development facility
  • A hot water heater as defined in the rule
  • A refining kettle covered by 40 CFR Part 63, Subpart X
  • An ethylene cracking furnace covered by 40 CFR Part 63, Subpart YY
  • Blast furnace stoves as described in the EPA document, “National Emission Standards for Hazardous Air Pollutants (NESHAP) for Integrated Iron and Steel Plants—Background Information for Proposed Standards” (EPA 453/R–01–005)
  • Any boiler or process heater specifically listed as an affected source in another standard(s) under 40 CFR Part 63 or subject to a standard established under Clean Air Act (CAA) Section 129
  • Temporary boilers as defined in the rule
  • Blast furnace gas fuel-fired boilers and process heaters as defined in the ruleBoiler MACT photo

Emission Limits
The HAP categories targeted by the proposed rule include mercury (Hg), non-mercury metal HAP, non-dioxin organic HAP, non-metal inorganic HAP, and dioxin/furans. EPA selected hydrogen chloride (HCl) as a surrogate for non-metal inorganic HAP, particulate matter (PM) as a surrogate for metal HAP, and carbon monoxide (CO) as a surrogate for non-dioxin organic HAP. Emission limits were developed based on fuel type for HCl, PM, and Hg, and based on fuel type and boiler design for CO and dioxin.

The units are divided into 11 subcategories depending on the fuel fired and the boiler design. EPA has proposed a 10 percent cutoff (on an annual average heat input basis) for determining the subcategory in which a boiler or process heats falls. The proposed emission limits (and for comparison, the emission limits in the vacated rule) are summarized in Table 1 for new sources and Table 2 for existing sources. As highlighted in the tables, the proposed limits are more stringent than the standards vacated in 2007. Additionally, the proposed rule includes a greater number of subcategories compared to the vacated rule.1

Consistent with the vacatur of provisions regarding HAP emissions during startup, shutdown, and malfunction (SSM), the proposed limits would apply at all times (i.e., there is no exclusion from the emission limits for periods of SSM). Periods of noncompliance during a malfunction will be evaluated on a case-by-case basis and EPA will consider efforts to minimize emissions, root cause analyses, and whether the event was a true malfunction and not the result or poor maintenance and/or careless operation. Although not subject to any emission limits, certain subcategories and heat input capacities are subject to work practice standards. New and existing natural gas- and refinery gas-fired units with a heat input capacity equal to or greater than 10 MMBtu/hr would be subject to a work practice standard consisting of annual tune-ups. Existing units of all fuel types with a heat input capacity less than 10 MMBtu/hr would be subject to a work practice standard consisting of tune-ups every two years.

Energy Assessment
The proposed rule includes a one-time energy assessment of cost-effective energy conservation measures that would be required for affected units. The energy audit must be completed by qualified personnel knowledgeable with evaluating energy systems and should include an assessment of the facility’s energy management program and practices using EPA’s ENERGY STAR Facility Energy Management Assessment Matrix. Facilities would be required to identify cost-effective solutions (those with a payback period of less than two years), but facilities are not required to implement findings of the audit. The procedures for an energy assessment are:

  • Conduct a visual inspection of the boiler system
  • Establish operating characteristics of the facility, energy system specifications, operating and maintenance procedures, and unusual operating constraints
  • Identify major energy consuming systems
  • Review available architectural and engineering plans, facility operation and maintenance procedures and logs, and fuel usage
  • Identify a list of major energy conservation measures
  • Determine the energy savings potential of the energy conservation measures identified
  • Prepare a comprehensive report detailing the ways to improve efficiency, the cost of specific improvements, benefits, and the time frame for recouping those investments

Source Testing
Annual stack testing is required to demonstrate compliance with the emission limits for each regulated pollutant, except for HCl and/or mercury if the fuel analysis option is utilized, or for CO or PM if continuous emissions monitoring is required. The performance tests consist of three, four-hour test runs. Stack testing can be reduced to once every three years if test results for three consecutive years show emissions at or below 75% of the limit. The reduction in stack testing frequency does not apply to dioxin/furan testing. The results of the annual stack test would be submitted using an EPA web-based electronic reporting tool (ERT). A site-specific test plan must be developed for performance tests.

Compliance Monitoring
If facilities use performance tests to demonstrate compliance with emission limits, they must develop a site-specific monitoring plan. The plan must be submitted to the permitting authority upon request, at least 60 days before the initial performance evaluation. The plan must address ongoing operation and maintenance, quality assurance, and recordkeeping and reporting.  

For operating limits that require the use of parametric monitoring, facilities will be required to install, operate, and maintain a continuous parameter monitoring system (CPMS). The following parameters, with compliance ranges established during performance tests, must be monitored using CPMS:

  • Wet Scrubber – Pressure drop, liquid flow rate, pH (for HCl control)
  • Dry Scrubber – Sorbent injection rate
  • Electrostatic Precipitator (with wet control systems) – Voltage and secondary current or total power input

Continuous Emissions Monitoring
For units with capacities equal to or greater than 100 MMBtu/hr, continuous emissions monitoring systems (CEMS) would be required for CO and oxygen. Compliance with the CO limit will be demonstrated using a 30-day rolling average.

For coal, biomass, and residual oil fired units equal to or greater than 250 MMBtu/hr, CEMS would be required for PM. Compliance with the PM emissions limit shall be determined based on the 24-hour daily (block) average of the hourly arithmetic average emissions concentrations using the CEMS data.

For units with an applicable opacity operating limit, continuous monitoring is required using a continuous opacity monitoring system (COMS). There are three specified exceptions to COMS monitoring:

  • Units equipped with wet scrubbers
  • Units with a heat input capacity 250 MMBtu/hr or greater (PM must be monitored)
  • Bag leak detection systems for fabric filter systems

The opacity limit is for dry control systems and is 10% opacity on a daily block average basis. As an alternative to installing COMS, for units controlled by fabric filters subject to opacity limits, facilities can install a bag leak detection system (BLDS). To demonstrate continuous compliance using a BLDS, facilities must: 1) initiate corrective action within one hour of a bag leak detection system alarm; 2) complete corrective actions as soon as practical; and 3) operate and maintain the fabric filter system such that the alarm does not sound more than five percent of the operating time during a six-month period.

Fuel Monitoring
As an alternative to operating add-on controls, facilities may elect to demonstrate the concentration of HAP in the fuel fired by the unit is below the emission limit. To demonstrate compliance with the mercury or HCl limits based on fuel analysis, monthly fuel analyses for each type of fuel burned are required. Facilities must develop and submit a site-specific fuel analysis plan to EPA for review and approval. When burning a new type of fuel, a fuel analysis must be conducted prior to burning the new type of fuel. Fuel usage (type and amount) must be recorded on a daily basis for each unit to demonstrate that no new fuels or solid waste has been burned in the unit.

Emissions Averaging
The option to comply with the emission limits using emission averaging is allowed only for existing affected units within the same subcategory. Emissions averaging is limited to PM, HCl, and mercury. A 10% discount factor is applied to the combined emissions average (i.e., combined emissions cannot exceed 90% of limit). If selecting emissions averaging for compliance, facilities must develop and implement an emissions averaging plan. The plan must be submitted for approval at least 180 days before averaging will begin.

Reporting
The timeline for notifications and reports required by the proposed rule are:

  • Initial Notification – No later than 120 days after the final rule is published in the Federal Register for existing sources or within 15 days of startup for new sources
  • Notification of Performance Test – No later than 30 days prior to conducting performance test
  • Notification of Compliance Status – No later than 60 days after the completion of the performance test/compliance evaluation
  • Notification of Natural Gas Curtailment - Within 48 hours of the declaration of a period of natural gas curtailment or supply interruption and intention to fire different fuel
  • Semiannual Compliance Report – Within 31 days from the end of the reporting period (January 1st through June 30th and July 1st through December 31st)

These reports are in addition to any reports required by the general provisions in Subpart A.

Health-Based Compliance Alternative
The current proposed rule does not include the Health Based Compliance Alternative (HBCA) that was included in the vacated 2004 Boiler MACT rule. The HBCA in the vacated 2004 Boiler MACT allowed facilities to comply with rule without add-on controls if no substantial risk to the public was demonstrated as a result of HCl and chlorine or manganese emissions from the affected sources. However, EPA is seeking comments on possible approaches to implement the HBCA in a final rule. EPA has identified several concerns where comments will be accepted, including the cumulative impact from multiple pollutants, selecting a surrogate pollutant, accounting for multiple sources within a single site or an industrial area, and how to adequately simulate exposure situations.

Area Source Boiler NESHAP
The newly proposed Area Source Boiler NESHAP (also called Area Source Boiler MACT/GACT) will affect boilers at area sources of HAP emission that burn coal, oil, or biomass, or non-waste materials, but not solid waste. EPA estimates that approximate 183,000 existing area source boilers at 92,000 U.S. facilities and approximately 6,800 new area source boilers over the next three years would be affected.

Applicability
The affected source for the proposed rule is the collection of existing and each new or reconstructed industrial, commercial, and institutional boilers at area sources. Note that process heaters are excluded from the proposed Area Source rule. A unit is classified as a new source if construction or fuel switching from natural gas to coal, biomass, or oil is commenced after June 4, 2010. It is important to note that the fuel switching applicability is unique to the Area Source Boiler MACT. Similarly, sources that are reconstructed (as defined in 40 CFR 63.2) after June 4, 2010 are classified as reconstructed sources. A boiler is classified as existing if it is not new or reconstructed. The compliance date for new sources is the date the final rule is published in the Federal Register or upon startup, whichever is later. The compliance date for existing sources is three years from the date the final rule is published in the Federal Register.The following units are exempt from the requirements of the rule:

  • Any boiler specifically listed as an affected source in another standard(s) under 40 CFR Part 63
  • Any boiler specifically listed as an affected source in another standard(s) established under Section 129 of the CAA
  • A boiler required to have a permit under Section 3005 of the Solid Waste Disposal Act or covered by Subpart EEE of this part (e.g., hazardous waste boilers)
  • A boiler that is used specifically for research and development (not including boilers that only provide steam to a process or for heating at a research and development facility)
  • A gas-fired boiler as defined in the proposed rule

Any source that was a major source and installed a control device on a boiler after November 15, 1990, and, as a result, became an area source under 40 CFR Part 63 is required to obtain a Title V operating permit.

Emission Limits
The proposed rule includes standards to limit emissions of mercury, PM (as a surrogate for non-mercury metals) and CO (as a surrogate for organic HAP), depending on new/existing status and fuel type. Existing small boilers (i.e., less than 10 MMBtu/hr) would not be subject to emission limits but would be required to perform a boiler tune-up every two years.

Standards for area sources can be based on either GACT or MACT. The proposed standards for existing coal-fired boilers and all new boilers are based on MACT for mercury and CO, and on GACT for PM. The proposed standards for existing biomass and oil-fired boilers are based on MACT for CO, and on GACT for mercury and PM. Emission limits are summarized in Table 3.

Similar to the proposed Major Source Boiler MACT, the emission limits apply at all times with no exemptions for exceedances during start-up, shutdown, or malfunctions.

Energy Assessment
Similar to the proposed Major Source rule, the proposed Area Source rule includes a one-time energy assessment of cost-effective energy conservation measures that would be required for existing units with heat input capacities greater than 10 MMBtu/hr. The same requirements and procedures for energy assessments required under the Major Source rule apply to area sources.

Source Testing
Annual stack testing is required to demonstrate compliance with the emission limits for each regulated pollutant (except for mercury if the fuel analysis option is utilized). The performance tests consist of three one-hour test runs for PM and CO and three, two-hour test runs for Hg. Stack testing can be reduced to once every three years if test results for three consecutive years show emissions at less than 75% of standard. The stack testing frequency reduction does not apply to CO testing. The results of the annual stack test would be submitted using EPA’s ERT.

Compliance Monitoring
If facilities use performance tests to demonstrate compliance with emission limits, they must develop a site-specific monitoring plan. The plan must be submitted to the permitting authority upon request, at least 60 days before the initial performance evaluation. The plan must address ongoing operation and maintenance, quality assurance, and recordkeeping and reporting.

For operating limits that require the use of a CMS, facilities will be required to install, operate, and maintain a CPMS. The sorbent injection rate for a dry scrubber must be monitored using CPMS. Other monitoring parameter alternatives are allowed pending approval by EPA.

Continuous Emissions Monitoring
For units with capacities equal to or greater than 100 MMBtu/hr, CEMS would be required for CO and oxygen. Compliance with the CO limit will be demonstrated using a daily average, unlike the 30-day rolling average in the proposed Major Source rule.

For units with an applicable opacity operating limit, continuous monitoring is required using a COMS. The opacity limit is for dry control systems and is 10% opacity on a daily block average basis. As an alternative to installing COMS, facilities can install a BLDS for units controlled by fabric filters subject to opacity limits. To demonstrate continuous compliance using a bag leak detection system, facilities must: 1) initiate corrective action within one hour of a bag leak detection system alarm; 2) complete corrective actions as soon as practical; and 3) operate and maintain the fabric filter system such that the alarm does not sound more than five percent of the operating time during a six-month period.

Fuel Monitoring
To demonstrate compliance with the mercury limits based on fuel analysis, monthly fuel analyses for each type of fuel burned are required. When burning a new type of fuel, a fuel analysis must be conducted prior to burning the new type of fuel. Fuel usage (type and amount) must be recorded on a monthly basis for each unit.

Reporting
The timeline for notifications and reports required by the proposed rule are:

  • Initial Notification – No later than 120 days after the final rule is published in the Federal Register for existing sources or within 120 days after the source becomes subject to the standard
  • Notification of Compliance Status – No later than 120 days after the applicable compliance date unless a performance test is required; in that instance, no later than 60 days after the completion of the performance test/compliance evaluation
  • Annual Compliance Certification Report – By March 1 of each year for the previous calendar year

These reports are in addition to any reports required by the general provisions in Subpart A.

Proposed Rule Timeline
The timeline of the proposed rules is as follows:

  • April 29, 2010 – Proposed rules signed
  • June 4, 2010 – Proposed rules published in the Federal Register
  • June 21, 2010 – Public hearing
  • July 19, 2010 – Comment period ends

The schedule for completing this rule is part of a court order, which requires the EPA Administrator to complete a final rule by December 16, 2010.

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