On December 20, 2012, U.S. EPA signed final amendments and revisions to the reconsidered 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 developed 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.
The final changes were made to rules that were promulgated on March 21, 2011 for both source categories. The proposed changes were proposed on December 23, 2011. The implementation and enforcement of these rules has been in limbo since EPA proposed reconsideration on the March 2011 rules. With these final rules, EPA has revised compliance dates for units affected by the rules. The final rules were published in the Federal Register on January 31, 2013 (major source rule) and February 1, 2013 (area source rule).
This rulemaking, like previous rulemakings, was promulgated along with the Nonhazardous Secondary Material (NHSM) and Commercial and Industrial Solid Waste Incineration (CISWI) rules in EPA’s latest attempt to finalize rules for various types of combustion units. The CISWI rule was published in the Federal Register on February 7, 2013.
Major Source Boiler MACT
The major source rule, known as the Boiler MACT, affects boilers and process heaters that burn coal, biomass, other non-waste solid fuels, liquid fuels, natural gas, refinery gas, and other gaseous fuels. The affected sources for the rule are the collection of existing and each new and reconstructed industrial, commercial, and institutional boilers and process heaters that do not burn solid waste at major sources of HAP emissions. The basic framework for the regulation remains the same. Departures from the March 21, 2011 rule are highlighted in the following sections.
The compliance date for new sources is date upon which the final rule was published in the Federal Register January 31, 2013, or upon startup, whichever is later. The compliance date for existing sources is January 31, 2016. In the final rule preamble, EPA noted that facilities may request a one-year extension of the compliance date for existing sources if the owner or operator can justify that additional time is needed (e.g., for air pollution control installation, constructing new energy sources). The date after which units are considered new or reconstructed under the rule remains June 4, 2010. A boiler or process heater is classified as existing if it is not new or reconstructed.
EPA also addressed transition between several related rules for CISWI units and Electric Generating Units (EGUs). For units transitioning from CISWI, compliance is required on the effective date of fuel switch and compliance must be demonstrated within 60 days of the effective date of the waste-to-fuel switch as identified under CISWI regulations. For former EGUs, compliance is required on the effective date of switch and compliance must be demonstrated within 180 days of becoming an affected source.
The HAP categories targeted by the rule remain unchanged and include mercury (Hg), non-mercury metal HAP, non-dioxin organic HAP, non-metal inorganic HAP, and dioxin/furans. While hydrogen chloride (HCl), particulate matter (PM), and carbon monoxide (CO) remain surrogates for non-metal inorganic HAP, metal HAP, and non-dioxin organic HAP, respectively, EPA finalized total selected metals (TSM) as an optional surrogate for metal HAP for solid fuel, liquid fuel, and Gas 2 units. TSM is defined as the combination of arsenic, beryllium, cadmium, chromium, lead, manganese, nickel and selenium. Emissions averaging is not a compliance option for TSM.
In contrast to the March 21, 2011 rule, EPA designated PM as a combustion-based pollutant for liquid and biomass units as a result of comments received from petitioners. For coal and solid fossil fuel units, PM was determined to be a fuel-based pollutant and a single emission limit was finalized for these units. The designations are contained in the final rule and EPA finalized 18 subcategories depending on the fuel fired and the boiler design when establishing emission limits. Major changes from the March 21, 2011 rule subcategories include:
- Adding a subcategory for coal/solid fossil fuel-fired fluidized bed units with an integrated heat exchanger
- Splitting the biomass stoker subcategory into wet stoker and kiln dried subcategories
- Splitting the suspension burner and Dutch oven subcategory into separate subcategories and including pile burners in the Dutch oven subcategory
- Splitting the liquid fuel subcategory into light liquid and heavy liquid subcategories
The following revised definitions were finalized based on the new subcategories:
- Light liquid includes distillate oil, biodiesel and vegetable oil
- Heavy liquid includes residual oil and any other liquid fuel not classified as a light liquid
- Hydrogen sulfide concentration limits were removed from the definition of other Gas 1 fuel (mercury concentration limits remain)
- A limited-use unit is any boiler or process heater that burns any amount of solid, liquid, or gaseous fuels and has a federally enforceable average annual capacity factor of no more than 10 percent
EPA included an alternate emission limit for units subject to a CO emission limit that elect to install and operate a continuous emissions monitoring system (CEMS) for CO. Compliance is demonstrated using a CO CEMS based on a 30-day rolling average for all units except for suspension burner and Dutch oven/pile burner biomass units, for which 10-day averaging periods apply.
EPA incorporated additional emission information received during the comment period in developing the revised emission limits. The emission limits in the original March 21, 2011 and current final rules are summarized in Table 1 for new sources and Table 2 for existing sources. For units constructed or reconstructed after June 4, 2010, but before January 31, 2013, EPA included interim emission limits that apply until January 31, 2016. These emission limits apply to new and existing boilers and process heaters with heat input greater than or equal to 10 MMBtu/hr. Unlike the March 21, 2011 rule, there are no numerical emission limits for dioxins/furans in the reconsidered rule for any subcategory. In lieu of numerical limitations, EPA has proposed work practice requirements.
Similar to the March 21, 2011 rule, the standards apply at all times (i.e., including periods of start-up, shut-down and malfunction). EPA clarified the affirmative defense language in the final rule to address violations during periods of malfunction and eliminated the 2-day notification and 45-day reporting requirements, instead requiring sources to include information in the next compliance report. In lieu of numerical emission limits, work practice standards apply during periods of startup and shutdown. The work practice standards for startups and shutdowns are identified as the following steps:
- Employ good combustion practices and demonstrate that good combustion practices are maintained by monitoring oxygen (O2) concentrations and optimizing those concentrations as specified by the boiler manufacturer
- Ensure that boiler operators are trained in startup and shutdown procedures, including maintenance and cleaning, safety, control device startup, and procedures to minimize emissions
- Maintain records during periods of startup and shutdown and include in compliance reports the O2 conditions/data for each event, length of startup/shutdown, and reason for event
Startup must occur using one or a combination of listed clean fuels. Once firing solid or Gas 2 fuels commences, emissions must be controlled by air pollution control devices required for normal compliance. Additionally, continuous monitoring systems must be operating during periods of startup and shutdown; however, emissions during startup and shutdown are excluded from 30-day or 10-day averaging periods.
EPA provided specific definitions of startup and shutdown in the final rule. Startup is defined as either the first-ever firing of fuel in a boiler or process heater for the purpose of supplying steam or heat for heating and/or producing electricity, or for any other purpose, or the firing of fuel in a boiler after a shutdown event for any purpose. Startup ends when any of the steam or heat from the boiler or process heater is supplied for heating, and/or producing electricity, or for any other purpose. Shutdown is defined as the cessation of operation of a boiler or process heater for any purpose. Shutdown begins either when none of the steam from the boiler is supplied for heating and/or producing electricity, or for any other purpose, or at the point of no fuel being fired in the boiler or process heater, whichever is earlier. Shutdown ends when there is no steam and no heat being supplied and no fuel being fired in the boiler or process heater.
EPA has retained the tune-up work practice standard requirements. As noted previously, the work practice standards replace dioxin/furan numerical emission limits. The requirement to optimize CO emissions must be consistent not only with the manufacturer’s specifications, but also with any specified NOx emission requirement for the unit. The frequency of tune-ups is summarized as follows:
- Every five (5) years for a new or existing boiler or process heater equipped with continuous oxygen trim systems or with heat input capacity of less than 5 MMBtu/hr in any of the following subcategories: unit designed to burn natural gas, refinery gas or other Gas 1 fuels; unit designed to burn Gas 2 (other); or unit designed to burn light liquid
- Every other year (biennially) for: a limited use boiler or process heater; a new or existing boiler or process heater with heat input capacity of less than 10 mmBtu/hr in the unit designed to burn heavy liquid solid fuel subcategories; a new or existing boiler or process heater with heat input capacity of less than 10 mmBtu/hr, but equal to or greater than 5 mmBtu/hr, in any of the following subcategories: unit designed to burn natural gas, refinery gas or other Gas 1 fuels; unit designed to burn Gas 2 (other); or unit designed to burn light liquid
- Annually for all other units
Tune-ups can be delayed for a specified period if it would require a unit shutdown, if scheduled for the next planned outage for units that sell electricity (not to exceed 36 months from last inspection), or can occur during the next planned entry into storage vessels or if they process equipment, if applicable.
For units that have not operated between the effective date and the compliance date specified for the source, the initial compliance demonstration must be completed within 180 days of restart and the initial tune-up must be completed within 30 days of restart. However, the one-time energy assessment must be completed by the compliance date.
The final rule maintains the one-time energy assessment requirement for existing units that was included in the March 21, 2011 rule. The rule clarifies the length and scope of the assessment, as well as specifying that the assessment must be completed before the compliance date. Notable scope clarifications include limiting the inventory of major energy systems to affected boilers and process heaters which are under control of the boiler/process heater owner or operator. Energy management systems compatible with ISO 50001 and include the affected units also satisfy the energy assessment requirement.
In the final rule, EPA included additional monitoring options for several pollutants and modified the averaging periods used to demonstrate continuous compliance. Compliance with operating parameters (e.g., sorbent injection, scrubber flow rate, scrubber pH, etc.) will be demonstrated based on a 30-day rolling average value, compared to the 12-hour block average in the March 21, 2011 rule. An oxygen trim system with the oxygen level set at the lowest level recorded during the performance test was included as an option to the requirement of operating an oxygen analyzer in the March 21, 2011 rule. EPA revised the definitions of “30-day rolling average” and “daily block average” to exclude periods of startup and shutdown or downtime from the arithmetic mean.
The March 21, 2011 rule had a PM CEMS requirement for coal, biomass and/or residual oil-fired boilers or process heaters having an average annual heat input greater than 250 MMBtu/hr. This requirement has been replaced with a PM continuous parameter monitoring system (CPMS) for boilers and process heaters combusting solid fossil fuel and/or residual oil (a PM CEMS remains an option). The PM CPMS basis must be in-stack or extractive light scatter, light scintillation, beta attenuation, or mass accumulation detection of PM in the exhaust gas or representative exhaust gas sample. The reportable measurement output from the PM CPMS may be expressed as milliamps, stack concentration, or other raw data signal. This revision eliminates the certification requirements of PM CEMS for subject units.
EPA has included the option to demonstrate continuous compliance with the HCl emission limits through the use of an SO2 CEMS. This method of demonstrating continuous compliance will be allowed only on a unit that utilizes a SO2 CEMS and an acid-gas control technology including wet scrubber, dry scrubbers and duct sorbent injection. Boilers or process heaters subject to an HCl emission limit that demonstrate compliance with an SO2 CEMS would be required to maintain the 30-day rolling average SO2 emission rate at or below the highest hourly average SO2 concentration measured during the most recent HCl performance test.
Area Source Boiler NESHAP
EPA finalized several changes and technical corrections to the final rule in this rulemaking. The compliance date for existing boilers (process heaters are not subject to this rule) remains March 21, 2014, as the changes do not affect facilities’ ability to comply with the rule. Like the March 2011 final rule, natural gas fired boilers and hot water heaters are not subject to the amendments to the area source Boiler MACT/GACT rule.
Applicability and Subcategory Clarifications
In the final rule, EPA included clarifications of rule applicability and subcategory revisions, which include:
- A new subcategory for seasonally operated boilers, which are boilers that undergo shutdowns for more than 7 consecutive months (or 210 consecutive days) due to seasonal conditions
- An exemption for temporary boilers, defined as any gaseous or liquid fuel boiler designed to, and capable of, being carried or moved from one location to another by means of, for example, wheels, skids, carrying handles, dollies, trailers, or platforms and meeting additional applicability criteria, similar to the major source rule
- A new subcategory for limited use boilers (same definition as the major source Boiler MACT rule)
- Clarification in the definition of natural gas curtailment
- Specifies that an existing dual-fuel fired boiler that has historically fired Gas I only will be subject to the existing unit solid fuel requirements if the unit chnages to solid biomass, or liquid fuel
EPA has exempted boilers subject to the rule from the requirement to obtain a Title V permit.
Work Practice Requirements
The tune-up requirements, except for the compliance dates, remain the same as the final rule. If an existing affected boiler is subject to a tune-up, the facility must comply with the work practice or management standard no later than March 21, 2014, an extension of the original compliance date.
In the March 21, 2011 rule, EPA required biennial tune-ups for all liquid fired boilers. In the amended final rule, liquid fired units less than 5 MMBtu/hr (new and existing), limited use units (new and existing), all seasonally operated units (new and existing), and boilers with oxygen trim systems must perform a tune-up every five years. Initial tune-ups for new units are required within 25 months or 61 months of startup for units subject to biennial and or five-year tune-ups, respectively.
Similar to the major source final rule, the area source final rule clarifies the length and scope of energy assessments. Additionally, energy assessments must be completed before the compliance date for existing sources (March 21, 2014).
The finalized rule revised mercury and carbon monoxide emissions limits for new and existing coal fired units of all sizes, while the remaining limits are unchanged. Emission limits in the final rule compared to the March 21, 2011 rule are summarized in Table 3. Oil-fired units that combust low sulfur (less than 0.5 weight percent) oil and do not utilize an add-on control device to reduce PM or SO2 are not subject to the PM emission limits.
Similar to the major source Boiler MACT, the standards apply at all times. Similar to the major source rule, EPA clarified the affirmative defense language for malfunctions in the final rule and revised notification and reporting requirements. In lieu of numerical emission limits, work practice standards apply during periods of startup and shutdown. The same definitions of startup and shutdown finalized in the major source rule are included in the area source rule.
In the final area source rule, EPA included the option to install and operate a CO CEMS and continuously monitor oxygen content to demonstrate compliance with the CO emission limits. Compliance with the CO emission limits will be based on the 10-day rolling average CO emission rate. Unlike the major source rule, the same emission limit applies regardless of the compliance demonstration option selected. In the final rule, EPA allowed for the use of oxygen trim analyzer systems to monitor oxygen concentration in the boiler. Similar to the major source rule, continuous compliance with operating parameters will be based on a 30-day rolling average.
With the January 31 publication in the Federal Register, the countdown to compliance officially begins. The first deadline will be the initial notification requirement, which is required by May 31, 2013 for major sources and January 20, 2014 for area sources, regardless of whether an initial notification under a previous version of the rules was submitted. With a final rule now in place, owners and operators can review how the final rules impact their facilities and evaluate current operations to develop a plan for compliance. Actions can include planning for potential pollution control installation by understanding emissions relative to limits (emissions testing may be required), determining reductions needed and evaluating technically feasible control technology options and continuous monitoring systems, if required. Additionally, review of energy certifications, monitoring plan updates, and necessary permitting will need to be completed to determine if any additional actions are required. Please contact your local Trinity office at (800) 229-6655 for assistance in the evaluation of compliance requirements to your facility.