Owners of industrial, commercial, and institutional boilers soon will be required to comply with new, stricter U.S. Environmental Protection Agency (EPA) air-emissions requirements. The new regulation, known as National Emission Standard for Hazardous Air Pollutants (NESHAP) for Industrial, Commercial, and Institutional Boilers, was issued in draft form by the EPA on April 29, 2010, and is expected to be finalized later this year. The regulation will affect thousands of boilers at facilities deemed to be major sources of hazardous air pollutants (HAPs).

Background
Section 112 of the Clean Air Act requires national emission standards for HAPs. The emission standards must reflect application of the maximum-achievable control technology (MACT). The EPA is tasked with developing MACT emission rules for specific industry groups, such as industrial, institutional, and commercial boilers.

On Feb. 26, 2004, NESHAP, commonly referred to as the Industrial Boiler MACT Rule, was finalized by the EPA. However, on June 8, 2007, the U.S. Court of Appeals for the District of Columbia Circuit issued a decision to vacate the Industrial Boiler MACT Rule, and the EPA was required to rewrite it. The EPA is accepting comments on the draft of the new rule, which must be finalized by Dec. 16. For more information, visit www.epa.gov/airquality/combustion.

Summary of the Rule
The Industrial Boiler MACT Rule applies to any industrial, commercial, or institutional boiler or process heater located at a major source of HAP emissions, which is defined as any stationary source or group of stationary sources located within a contiguous area and under common control that emits, or has the potential to emit, 10 tons or more per year of any single HAP or 25 tons per year of any combination of HAPs. The rule requires each boiler at a facility to meet emission limits or work-practice standards, meet operating limits, and demonstrate compliance on an annual and continuous basis.

Emission Limits and Work Practice Requirements
For all natural-gas- and refinery-gas-fired units and all existing units with a heat-input capacity of less than 10 MMBtuh, the rule establishes a work-practice standard instead of emission limits. The work-practice standard requires an annual tuneup for each natural-gas- and refinery-gas-fired boiler and a biennial tuneup for each existing boiler with a heat-input capacity of less than 10 MMBtuh.

For all other boilers (essentially all boilers that do not burn natural or refinery gas and have a heat-input capacity of greater than 10 MMBtuh), the rule sets emission limits for HAPs or HAP surrogates, including:

• Particulate matter (PM) as a surrogate for non-mercury metallic HAPs.
• Mercury (Hg).
• Hydrogen chloride (HCl) as a surrogate for acid-gas HAPs.
• Carbon monoxide (CO) as a surrogate for non-dioxin organic HAPs.
• Dioxin/furan.

The emission limits are based on a subcategorization of sources based on boiler status (existing or new), fuel type, and boiler type, as shown in Table 1.

Emission limits apply at all times, including periods of startup, shutdown, and malfunction. Also, facilities are allowed to comply with PM, HCl, and Hg limits by using emissions averaging, provided the average emissions are within 90 percent of the emission limit.