Emission Controls for Small Wood-Fired Boilers - Western Forestry ...

11.0 RECOMMENDATIONS FOR FUTURE RESEARCH
A number of factors affect emission rates, such as geographic location, type of fuel burned, firing rate
characteristics, type of combustion technology, and type of add‐on emission control. Additional emission
tests will improve understanding of how these factors affect emission levels. Future emission tests could
be structured for wood chip and wood pellet systems as follows:
1. Inlet‐outlet testing for particulate emissions (PM10, PM2.5) controlled by ESPs, baghouses and
HEMCs. Particle size distribution should also be measured at the inlet and outlet, in addition to
measuring mass emission rates.
2. HAP emissions in concert with CO and PM2.5. Inlet and outlet testing should be performed for
particulate HAPs. PM2.5 should be tested because it is considered a surrogate for particulate
HAPs. CO should be tested (outlet testing only) because it is considered a surrogate for gaseous
HAPs.
3. Stack testing for any given site should be expanded to include emissions from the following:
a. Low, medium and high firing rates
b. At least two fuels, such as, wood with bark (bole chips or whole tree chips) and wood
without bark (mill chips).
Attention should also be given to the following:
1. Development of a voluntary universal boiler operator training program for obtaining boiler
operator certification.
2. Further development of fuel quality specifications to further establish grades of wood fuels.
12.0 SUMMARY
A number of emission controls for small wood‐fired boilers have been evaluated. This study evaluated a
number of Best Management Practices (BMPs – also called work practice standards) and add‐on controls.
While these controls are focused on particulate matter control, their implementation will control
emissions of all types of pollutants, including carbon monoxide, sulfur dioxide, nitrogen oxides, volatile
organic compounds and hazardous air pollutants. Maximizing fuel quality, optimizing combustion
conditions and selecting a well designed add‐on pollution control are the three main categories for
controlling emissions. Control efficiency and cost effectiveness vary by boiler size, particle size
distribution and type of add‐on pollution control.
Resource Systems Group, Inc.
Emission Control Technologies for Small Wood‐Fired Boilers
6 May 2010 Page 26