Advantages of Using a Process Hg CEMS
By: Jerry Amrhein, ADA-ES
For the EUEC Conference in San Diego, CA, February 16-18, 2015
© 2015 ADA-ES, Inc.
What is a Process Hg CEMS?
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A Process Hg CEMS is any Hg CEMS in which the mercury
measurement is used in a feedback loop to control a
mercury reduction process such as Activated Carbon
Injection (ACI), Coal Halogen Injection (CHI), etc.
© 2015 ADA-ES, Inc.
What is a Process Hg CEMS?
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A Process Hg CEMS is any Hg CEMS in which the mercury
measurement is used in a feedback loop to control a
mercury reduction process such as Activated Carbon
Injection (ACI), Coal Halogen Injection (CHI), etc.
It can be a compliance system or a CEMS specially
designed for process control.
© 2015 ADA-ES, Inc.
What is a Process Hg CEMS?
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A Process Hg CEMS is any Hg CEMS in which the mercury
measurement is used in a feedback loop to control a
mercury reduction process such as Activated Carbon
Injection (ACI), Coal Halogen Injection (CHI), etc.
It can be a compliance system or a CEMS specially
designed for process control.
CEMS designed only for process control tend to be
simplified versions of compliance systems because they
do not have to meet the strict QA/QC requirements.
© 2015 ADA-ES, Inc.
Factors Affecting Hg Emissions
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Coal Hg
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CoalQUAL Hg Data
• In General, Coal Hg can vary by 5 lb/TBtu across the same seam.
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CoalQUAL Hg Data
• In General, Coal Hg can vary by 5 lb/TBtu across the same seam.
• If you don’t have a continuous Hg reading, you have to assume
the highest value.
© 2015 ADA-ES, Inc.
Factors Affecting Hg Emissions
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Coal Hg
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Coal Halogen Concentration
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Factors Affecting Hg Emissions
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Coal Hg
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Coal Halogen Concentration
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Burner Performance (unburned carbon-LOI)
© 2015 ADA-ES, Inc.
Factors Affecting Hg Emissions
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Coal Hg
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Coal Halogen Concentration
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Burner Performance (unburned carbon-LOI)
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SCR Operations - Excess SO3 and NH3
© 2015 ADA-ES, Inc.
Factors Affecting Hg Emissions
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Coal Hg
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Coal Halogen Concentration
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Burner Performance (unburned carbon-LOI)
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SCR Operations - Excess SO3 and NH3
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Wet Scrubber Chemistry - Hg Re-emissions
© 2015 ADA-ES, Inc.
Factors Affecting Hg Emissions
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Coal Hg
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Coal Halogen Concentration
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Burner Performance (unburned carbon-LOI)
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SCR Operations - Excess SO3 and NH3
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Wet Scrubber Chemistry - Hg Re-emissions
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Boiler Load (temperature and gas flow)
© 2015 ADA-ES, Inc.
Factors Affecting Hg Emissions
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Coal Hg
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Coal Halogen Concentration
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Burner Performance (unburned carbon-LOI)
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SCR Operations - Excess SO3 and NH3
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Wet Scrubber Chemistry - Hg Re-emissions
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Boiler Load (temperature and gas flow)
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SO3 Conditioning for ESPs
© 2015 ADA-ES, Inc.
Factors Affecting Hg Emissions
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Coal Hg
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Coal Halogen Concentration
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Burner Performance (unburned carbon-LOI)
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SCR Operations - Excess SO3 and NH3
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Wet Scrubber Chemistry - Hg Re-emissions
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Boiler Load (temperature and gas flow)
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SO3 Conditioning for ESPs
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Gas Temperature
© 2015 ADA-ES, Inc.
Factors Affecting Hg Emissions
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Coal Hg
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Coal Halogen Concentration
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Burner Performance (unburned carbon-LOI)
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SCR Operations - Excess SO3 and NH3
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Wet Scrubber Chemistry - Hg Re-emissions
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Boiler Load (temperature and gas flow)
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SO3 Conditioning for ESPs
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Gas Temperature
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Add Rate of Mercury Control Agent (PAC, Halogen)
© 2015 ADA-ES, Inc.
Plants That Can Benefit Most
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Plants Opting to use Sorbent Traps for MATS Compliance
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Plants using ACI, CHI or other Hg Control Agent
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Plants Using Sorbent Traps for MATS
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Sorbents Traps
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One data point per week
What a Process Hg CEMS Offers
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Continuous readout
Operate closer to emission limits
Less chance of non-compliance
Integration with feedback control
Lower O&M Costs
© 2015 ADA-ES, Inc.
Plants Using ACI for Hg Control
Assumptions:
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Typical 500 MW as per B&W’s 40th Edition of “Steam”.
PAC cost of $1.00/lb.
Boiler availability = 70%.
No significant native Hg capture
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Plants Using ACI for Hg Control
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Plants at a Fixed ACI Rate
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ACI reduction of 0.25 lb/MMacf saves $140,000/yr.
© 2015 ADA-ES, Inc.
Summary of Advantages
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Lower Cost than a Compliance System
Little chance of Non-Compliance
Continuous Readout
Feedback Control
Less QA/QC
Lower O&M
Short Return on Investment
Integration with EXPERTi
© 2015 ADA-ES, Inc.
Interested in Learning More?
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Visit the ADA-ES Booth:
910
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Questions?
© 2015 ADA-ES, Inc.