Air pollutant emission standards for boilers and process heaters

On April 29, 2010, the US Environmental Protection Agency (EPA) proposed three rules to regulate hazardous air emissions from commercial, institutional and industrial boilers, process heaters and incinerators at major and area sources.

One of the proposed rules addresses boilers at area sources – facilities that potentially emit less than 10 tons per year (tpy) of any single hazardous air pollutant or 25 tpy of combined air toxics. The rule will apply to facilities with boilers that burn coal, oil or biomass (i.e., wood), but not waste materials. New boilers that burn coal would need to meet emission standards for mercury, particulates and carbon monoxide. New boilers burning oil or biomass will need to meet emission limits for particulates and carbon monoxide. Existing large boilers (heat input of 10 million Btu/hr or greater) that burn coal will be required to meet emission limits for mercury and carbon monoxide; existing large boilers that are oil or biomass-fired will have an emission limit for carbon monoxide, only. The rule requires that all facilities with large boilers conduct an energy assessment to identify practicable conservation measures. Facilities with small boilers will be required only to conduct a boiler tune-up at least once every two years.

The second rule applies to boilers and process heaters at major source facilities. The rule will apply to boilers that burn natural gas, fuel oil, coal, biomass or other gas, but not waste, and to process heaters (which heat raw or intermediate materials in an industrial process).

The rule applies requirements based on categories of boilers and process heaters:

  • for new and existing natural gas and refinery gas-fired units, an annual tune-up would be required;
  • for small (less than 10 million Btu/hr) existing units, a tune-up would be required every two years;
  • all existing major sources will conduct an energy assessment;
  • emission limits for mercury, dioxin, particulates, hydrogen chloride and carbon monoxide will be established for all other covered boilers and process heaters.

The third rule will amend requirements for commercial and industrial, but not municipal, solid waste incinerators (CISWI). This rule applies to devices that burn solid waste at a commercial or industrial facility, such as units designed to discard solid waste, energy recovery units, waste burning kilns that combust solid waste in the manufacturing process and burn-off ovens used to remove residual material from racks, hooks, parts or drums to allow their reuse in production processes. The rule will establish emission limitations for nine (9) pollutants emitted by CISWI units. The proposed rule also will require stack testing, additional monitoring, annual inspections of emission control devices and other compliance procedures.

Separately, EPA also has proposed a new definition of solid waste for non-hazardous, secondary materials that are burned in combustion units. This proposal will affect whether certain boilers will be regulated as commercial / industrial boilers or as CISWI units. More information on the proposed solid waste definition can be found at http://www.epa.gov/wastes/nonhaz/definition.htm.

More information including the texts of the proposed air toxics rules can be found at http://epa.gov/airquality/combustion/actions.html.