In situ optical absorption mercury continuous emission monitor

Area of Science:

• Environmental Science
• Analytical Chemistry
• Chemical Engineering

Background:

• Coal-fired power plants are significant sources of elemental mercury (Hg(0)) emissions.
• Accurate real-time monitoring of Hg(0) is crucial for environmental regulation and control.

Purpose of the Study:

• To develop and validate an in situ continuous emission monitor (CEM) for elemental mercury (Hg(0)).
• To enable real-time measurement of Hg(0) in the exhaust streams of coal-fired power plants.

Main Methods:

• Utilized ultraviolet atomic absorption spectroscopy with a mercury lamp.
• Incorporated a light-emitting diode (LED) background correction system to isolate Hg(0) absorption.
• Conducted laboratory investigations and field tests in a 230 MW coal-fired power plant.

Main Results:

• Achieved a laboratory limit of detection of 2 µg/m³ for Hg(0) with a 1-min average and 49 cm path length.
• Anticipated limit of detection below 0.2 µg/m³ in a 7 m diameter stack.
• Successfully demonstrated operability and recorded initial Hg(0) concentrations in field tests.

Conclusions:

• The developed in situ CEM is a viable tool for monitoring Hg(0) emissions from coal-fired power plants.
• Further validation against standard methods is required to confirm measurement accuracy.
• This technology offers potential for improved environmental compliance and mercury emission control.