Wood-Fired Boiler Emission Control Update Prepared for: 2010 Vermont Wood Chip Users Conference January 19, 2010
Overview Quick review of add-on emission controls What s new? Best Management Practices (BMPs) Electrostatic Precipitators (ESPs) advantages Parting thoughts Photo provided by the Biomass Energy Resource Center (BERC) 2
Quick Review of Common Add-On Pollution Controls Mechanical collectors Use inertial separation Commonly found on smaller school systems (< 10 MMBtu/hr) Types: single cyclones, multi-cyclones, high efficiency multicyclones, core separators Baghouses Use fabric filtration Common on larger systems (> 10 MMBtu/hr) Electrostatic precipitators (ESPs) Use electrostatic attraction Common on very large systems (> 100 MMBtu/hr) and about to become common on smaller systems 3
Add-On Pollution Controls Single Cyclone High Efficiency Multi-Cyclone Photos provided by the Biomass Energy Resource Center (BERC) 4
Add-On Pollution Controls Core Separator Photo provided by Easom Consulting 5
Add-On Pollution Controls 6
Add-On Pollution Controls 7
What s new? Stricter emission limits should become reality in 2010 Vermont APCD control study completed (inlet/outlet testing at 5 NE sites) First pellet boiler stack emission test completed (2.8 MMBtu/hr system) Best Management Practices (BMPs) can substantially reduce emissions Mechanical collector performance sub-optimal Electrostatic Precipitators (ESPs) have many potential advantages 8
ESP Benefits More economical than originally thought, but still expensive relative to simple mechanical collectors Occupy a small footprint Can be installed outdoors Less ancillary equipment (eg insulated ductwork) Relatively low power requirements relative to all add-on pollution controls Low maintenance relative to baghouse 9
ESP Benefits Photo courtesy of BETH ESPs 10
Best Management Practices (BMPs) Focus historically on add-on controls. Need more BMPs Also called work practice standards In short what can be done upstream of the pollution control device to reduce emissions? Improve system efficiency (reduce fuel consumption and emissions) Improve system performance (avoid upset conditions with uniform fuel) Data reviewed and work experiences indicate they do make a difference Poor fuel quality doubled normal level particulate emissions Boiler tune up reduced particulate emissions by approx 60% Lower ash content fuel eliminated clinkers and saved grates 11
Best Management Practices (BMPs) partial list Fuel quality Operation and maintenance plan Boiler operator training Equipment sensors Automatic ash removal Raking grates Combustion efficiency testing Visual plume observations Annual tune up 12
Parting Thoughts BMPs can save energy, reduce emissions and eliminate hassles Consider designing emission control systems to meet stricter emission limits ESP looks like a good bet, but don t rule out other options Don t bet on conventional mechanical collectors to meet stricter emission limits Mechanical collectors should maintain pressure drop over all firing rates Final USFS emissions report in a few months 13
Emissions Controls for Wood Boilers Contact Information John Hinckley Resource Systems Group, Inc. 55 Railroad Row White River Junction, VT 05001 802/295-4999 jhinckley@rsginc.com www.rsginc.com 14