Mercury Control Technologies

Utility MACT Working Group

May 30, 2002

Mercury Control Overview

• Mercury emissions dependent on:– mercury content of coal– combustion and physical characteristics of unit– emission control technologies employed

Mercury Content of Coal

• Assumptions on the mercury content of coal are derived from EPA’s ICR data

– over 40,000 data points indicating coal type, sulfur content, and mercury content

• ICR data points grouped by IPM coal types and IPM coal supply regions

– clustering analysis was used to map the weighted average mercury content for a specific coal type-supply region

Mercury Content of Coal

Mercury Emission Modification Factors

• ICR data was used to derive EMFs

• EMF dependent on unit’s burner type, particulate control, and NOx and SO2 control

• Mercury reduction achieved is 1-EMF

• EMF varies by the type of coal

– subbituminous and lignite coal assumed to have same EMFs

Mercury Emission Modification Factors

Mercury Control Capabilities

• Two retrofit options in IPM for mercury control:

– Activated carbon injection (ACI)

– SO2/NOx retrofits

• Wet FGD + SCR

• Wet FGD + SNCR

• Mercury removal for SO2/NOx retrofits based on EMF assumptions

• Mercury removal for ACI currently at 80%

ACI Costs

• ACI cost and performance were obtained from study by DOE NETL and EPA ORD

• NETL-ORD study developed capital, FOM, and VOM costs of different components of ACI retrofit– Spray cooling– Sorbent injection– Sorbent disposal– Pulse-jet fabric filter

• Separate cost functions for 26 control configurations and coal types were developed for a range of mercury removal rates

• Equations found in Appendix 5.3

ACI Costs

ACI Costs

• Several steps were taken to adapt these equations for use in IPM:– NETL/ORD equations reduce to function of unit

capacity and heat rate– Used average heating values of coal to convert sulfur

by weight into lbs of sulfur per mmBtu– Polynomial fits used to incorporate equations into IPM– Assumption of 80% removal used to develop

polynomial fits• Table 5.8 provides example costs for 500 MW unit with

heat rate of 10,000 Btu/kWh

ACI Costs