January 19, 2010

Wood-Fired Boiler Emission Control Update

Prepared for:2010 Vermont Wood Chip Users Conference

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Wood-Fired Boiler Emission Control Update

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)

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Wood-Fired Boiler Emission Control Update

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 multi-

cyclones, 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

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Wood-Fired Boiler Emission Control Update

Photos provided by the Biomass Energy Resource Center (BERC)

Add-On Pollution Controls

Single Cyclone

High Efficiency Multi-Cyclone

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Wood-Fired Boiler Emission Control Update

Photo provided by Easom Consulting

Add-On Pollution Controls

Core Separator

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Wood-Fired Boiler Emission Control Update

Add-On Pollution Controls

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Wood-Fired Boiler Emission Control Update

Add-On Pollution Controls

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Wood-Fired Boiler Emission Control Update

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

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Wood-Fired Boiler Emission Control Update

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

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Wood-Fired Boiler Emission Control Update

ESP Benefits

Photo courtesy of BETH ESPs

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Wood-Fired Boiler Emission Control Update

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

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Wood-Fired Boiler Emission Control Update

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

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Wood-Fired Boiler Emission Control Update

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

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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