APC Strategy for Mercury CEMS
by Trey Lightsey
2010 Annual Meeting & Technical Conference
A&WMA – Southern Section
Renaissance Riverview Plaza Hotel
Regulatory Overview – Timeline
2000 – Clinton EPA will regulate mercury from coal-fired utility boilers under Section 112
of the CAA (Clean Air Act)
2004 – Bush EPA decides that listing coal-fired utility boilers under Section 112 of the
CAA was ‘in error’
2005 – Bush EPA issues CAMR (Clean Air Mercury Rule) delisting EGUs from Section
112 of the CAA and establishing a mercury trading program
2008 – DC Court of Appeals vacates CAMR
2009 – Obama EPA will develop emission standards for HAPs (Hazardous Air Pollutants)
under Section 112 of the CAA and announces an ICR (Info Collection Request) to
collect HAP data from utility boilers
2011 – Per a consent decree, a draft of the HAPs Utility MACT (Maximum Achievable
Control Technology) is due in March which will set final emission limits by November
2014 – All affected utilities must be in compliance with the HAPs Utility MACT by
November (3 years post-submittal of the final rule)
APC Strategy for Mercury CEMS – Overview
– 15 TMFS (Thermo Mercury Freedom Systems) Hg CEMS were
implemented at 6 coal-fired steam plants as part of the vacated CAMR.
– 7 Hg CEMS were relocated to wet stacks with the addition of FGDs.
– Each Hg CEMS was certified per the vacated CAMR which included a
cycle (response) time test, a 3 pt linearity, a 3 pt system integrity check,
a calibration error test (7 day drift) and a RATA.
– Daily, weekly, quarterly and annual QA/QC (including 30B RATAs for
annual recertification) is being performed.
– Efforts similar to the APC Strategy for Hg CEMS are necessary to
advance source monitoring technology and to set realistic maintenance
and budgeting expectations ahead of implementing new Utility MACTs
and other monitoring requirements. There will be lessons learned from
Hg CEMS that will apply to other HAPs monitoring.
APC Strategy for Mercury CEMS – TMFS
APC Strategy for Mercury CEMS – RATAs
– Method 30B
– A known volume of flue gas is extracted from a stack/duct through paired, sorbent
media traps at a pre-determined flow rate; the traps are recovered from the
sampling system and analyzed by any suitable determinative technique that can
measure total vapor phase mercury and meet performance criteria
– Sampling
– APC field services performs the sampling portion of the RATA using 2-bed, iodated,
activated carbon traps from Ohio Lumex
– Sorbent trap sampling system is an Apex XC-6000EPC
– Method 4 moisture determination using an Apex XC-40 console
– Analysis
– APC field services using an Ohio Lumex RA-915+ Zeeman Mercury Spectrometer
with RP-M324 attachment
– APC environmental test lab using a Leco AMA254 Mercury Analyzer
APC Strategy for Mercury CEMS – Sampling
Sorbent bed 2
Sorbent bed 1
Flue gas
Quartz cotton 1
Quartz cotton 2
APC Strategy for Mercury CEMS – Sampling
APC Strategy for Mercury CEMS – Analysis
Method 30B Data Input
Train Trap
ID
ID
1A
1B
2A
2B
3A
3B
4A
4B
5A
5B
6A
6B
7A
7B
8A
8B
9A
9B
10A
10B
11A
11B
12A
12B
63261
63298
63245
63274
61114
63171
61117
63193
61152
63194
61112
63197
61151
63230
63199
63272
63704
63717
Date
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
6/1/2010
Time
7:29-7:59
7:29-7:59
8:09-8:39
8:09-8:39
8:51-9:21
8:51-9:21
9:31-10:01
9:31-10:01
10:11-10:41
10:11-10:41
11:14-11:44
11:14-11:44
11:56-12:26
11:56-12:26
1:08-1:38
1:08-1:38
1:57-2:27
1:57-2:27
Break Pair Trap Spike
Spike
Std
Dry Basis Wet Basis Avg Wet
FRT - 3
Field
Sec 1
Sec 2
Tot Mass through Agree
Mass (ng) Conc
Sample Conc
Conc
Basis Conc
runs (85- M.4
Recovery
Mass (ng) Mass (ng) (ng)
(<10%) (<10%) (50-150%) (ng/L)
Vol (L) (ng/L)
(ng/L)
(ng/L)
Note
115%) Mois
97.5%
107.00
0.00
107.00
0.0%
0
28.919
3.70
3.41
2.7%
7.79%
3.52
113.00
0.00
113.00
0.0%
0
28.651
3.94
3.64
117.00
0.00
117.00
0.0%
0
28.741
4.07
3.75
3.1%
7.79%
3.66
110.00
0.00
110.00
0.0%
0
28.474
3.86
3.56
236.00
0.00
236.00
0.0%
100
28.645
4.75
4.28
3.0%
3.71 106.3%
9.75%
4.19
128.00
0.00
128.00
0.0%
0
28.273
4.53
4.09
242.00
0.00
242.00
0.0%
100
28.543
4.97
4.49
2.9%
3.79 108.2%
9.75%
4.36
134.00
0.00
134.00
0.0%
0
28.580
4.69
4.23
266.00
0.00
266.00
0.0%
100
28.348
5.86
5.32
0.3%
3.45 97.9%
9.18%
5.35
167.00
0.00
167.00
0.0%
0
28.169
5.93
5.38
271.00
0.00
271.00
0.0%
100
28.895
5.92
5.37
1.2%
3.46 100.1%
9.18%
5.37
167.00
0.00
167.00
0.0%
0
28.230
5.92
5.37
257.00
0.20
257.20
0.1%
100
28.900
5.43
4.95
0.3%
3.27 94.5%
8.82%
5.04
156.00
0.00
156.00
0.0%
0
27.738
5.62
5.13
162.00
0.10
162.10
0.1%
0
29.128
5.56
5.07
0.9%
8.82%
5.13
159.00
0.00
159.00
0.0%
0
27.892
5.70
5.20
156.00
0.00
156.00
0.0%
0
29.059
5.37
4.83
0.6%
10.09%
4.90
154.00
0.00
154.00
0.0%
0
27.838
5.53
4.97
0.00 #DIV/0!
0
#DIV/0!
#DIV/0!
#DIV/0!
#DIV/0!
0.00 #DIV/0!
0
#DIV/0!
#DIV/0!
0.00 #DIV/0!
0
#DIV/0!
#DIV/0!
#DIV/0!
#DIV/0!
0.00 #DIV/0!
0
#DIV/0!
#DIV/0!
0.00 #DIV/0!
0
#DIV/0!
#DIV/0!
#DIV/0!
#DIV/0!
0.00 #DIV/0!
0
#DIV/0!
#DIV/0!
APC Strategy for Mercury CEMS – Analysis
APC Strategy for Mercury CEMS – Ex.1
• Ex.1 is an 800MW unit that burns mainly Columbian coal and is equipped with an
SCR and FGD
• Initially, the Hg CEMS was located on an exterior duct leading to a single lined, dry
stack downstream of an SCR
• The dry duct hourly Hg concentrations varied in the 2 – 8ug/scm range during the
certified period (Jun 09’ – Sep 09’) and depended primarily upon operating variables
(load, fan/flow, coal variations, PCD operation, etc.)
• There was 99+% data availability* during the certified period on the dry duct
• The Hg CEMS is currently located in the annulus space of a single-lined wet stack
downstream of all PCDs (SCR and FGD) at an elevation of ~500’ft
• The wet stack hourly Hg concentrations have varied in the 0.1 – 4ug/scm range
since certification in Jun 10’
• Currently maintaining 99+% data availability* on the wet stack
*availability is based on hourly averages; an available hour is one in which a previous 24hr (daily calibration)
was successful and there are at least 2 minutes of valid data in each of the 4 hourly quadrants
APC Strategy for Mercury CEMS – Ex.1
RATA results - DRY performed on 6/17/09; FGD performed on 6/29/10
Ex.1 Hg CEMS RATA Comparison
10.00
9.00
8.00
7.00
ug/scm
6.00
RM 30B (DRY)
5.00
Hg CEMS (DRY)
4.00
RM 30B (FGD)
3.00
Hg CEMS (FGD)
2.00
1.00
0.00
1
2
3
4
5
Run
6
7
8
9
APC Strategy for Mercury CEMS – Ex.2
• Ex.2 is a 750MW unit that burns mainly Western PRB coal and is equipped with an
SCR and FGD
• Initially, the Hg CEMS was located in the annulus space of a dual-lined dry stack
downstream of an SCR
• The dry stack hourly Hg concentrations varied in the 2 – 12ug/scm range during the
certified period (Aug 08’ – May 10’) and depended primarily upon operating variables
(load, fan/flow, coal variations, PCD operation, etc.)
• There was 87+% data availability* during the certified period on the dry stack
• The Hg CEMS is currently located in the annulus space of a dual-lined wet stack
downstream of all PCDs (SCR and FGD) at an elevation of ~500’ft
• The wet stack hourly Hg concentrations have varied in the 2 – 6ug/scm range since
certification in May 10’
• Currently maintaining 98+% data availability* on the wet stack
*availability is based on hourly averages; an available hour is one where a previous 24hr (daily calibration)
was successful and there are at least 2 minutes of valid data in each of the 4 hourly quadrants
APC Strategy for Mercury CEMS – Ex.2
RATA Results – DRY performed on 7/28/09; FGD performed on 5/12/10
Ex.2 Hg CEMS RATA Comparison
10.00
9.00
8.00
7.00
ug/scm
6.00
RM 30B (DRY)
5.00
Hg CEMS (DRY)
4.00
RM 30B (FGD)
3.00
Hg CEMS (FGD)
2.00
1.00
0.00
1
2
3
4
5
Run
6
7
8
9
APC Strategy for Mercury CEMS – Ex.3
• Ex.3 is a 900MW unit that burns mainly Alabama coal and is equipped with an SCR
and FGD
• Initially, the Hg CEMS was located on an exterior duct leading to a single lined, dry
stack downstream of an SCR
• The dry duct hourly Hg concentrations varied in the 2 – 10ug/scm range during the
certified period (June 08’ – Aug 09’) and depended primarily upon operating
variables (load, fan/flow, coal variations, PCD operation, etc.)
• There was 85+% data availability* during the certified period on the dry duct
• The Hg CEMS is currently located in the annulus space of a single-lined wet stack
downstream of all PCDs (SCR and FGD) at an elevation of ~500’ft
• The wet stack hourly Hg concentrations have varied in the 0.1 – 5ug/scm range
since certification in Apr 10’
• Currently maintaining 93+% data availability* on the wet stack
*availability is based on hourly averages; an available hour is one in which a previous 24hr (daily calibration)
was successful and there are at least 2 minutes of valid data in each of the 4 hourly quadrants
APC Strategy for Mercury CEMS – Ex.3
RATA Results – DRY performed on 8/4/09; FGD performed on 3/31/10
Ex.3 Hg CEMS RATA Comparison
10.00
9.00
8.00
7.00
ug/scm
6.00
RM 30B (DRY)
5.00
Hg CEMS (DRY)
4.00
RM 30B (FGD)
3.00
Hg CEMS (FGD)
2.00
1.00
0.00
1
2
3
4
5
Run
6
7
8
9
APC Strategy for Mercury CEMS – Ex.4
• Ex.4 is comprised of (2) 300MW units that burn mainly Alabama coal and is
equipped with an ESP (only)
• The Hg CEMS is located in the annulus space of a single-lined dry stack
downstream of the ESP at an elevation of ~300’ft
• The dry stack hourly Hg concentrations have varied in the 10 – 30ug/scm range
since certification in Jan 09’ and depend primarily upon load and coal variations
• Currently maintaining 90+% data availability* on the dry stack
*availability is based on hourly averages; an available hour is one in which a previous 24hr (daily calibration)
was successful and there are at least 2 minutes of valid data in each of the 4 hourly quadrants
APC Strategy for Mercury CEMS – Ex.4
Diff
#DIV/0!
1.66
0.17
1.15
0.34
1.62
1.80
2.11
0.97
1.80
#DIV/0!
#DIV/0!
1.29
Ex.4 Hg CEMS Recertification RATA 100713
40.00
35.00
30.00
25.00
ug/scm
Used =1
RM 30B Hg CEMS
Not = 0 Run Time
Date
(ng/L) (ug/scm)
0
1
0:00
1/0/1900 #DIV/0! #DIV/0!
1
2
7:39-8:09
7/13/2010 25.20
26.87
1
3
8:24-8:54
7/13/2010 26.62
26.45
1
4
9:05-9:35
7/13/2010 24.89
26.05
1
5 9:48-10:18
7/13/2010 24.35
24.69
1
6 10:29-10:59
7/13/2010 22.77
24.38
1
7 11:11-11:41
7/13/2010 21.41
23.21
1
8 11:57-12:27
7/13/2010 20.41
22.53
1
9 12:46-1:16
7/13/2010 21.54
22.50
1 10
1:25-1:55
7/13/2010 21.25
23.05
0 11
0:00
1/0/1900 #DIV/0! #DIV/0!
0 12
0:00
1/0/1900 #DIV/0! #DIV/0!
Mean
23.16
24.41
Std Dev
0.683
Conf Coef
0.510
Rel Accuracy 7.78%
RATA Status PASS
Tvalue
2.306
Bias
1.053
RM 30B
20.00
Hg CEMS
15.00
10.00
5.00
0.00
1
2
3
4
5
Run
6
7
8
9
Lessons Learned, Challenges and Next Steps
• Mercury removal (generally) occurs in the FGD (absorber solution) when gaseous phase Hg 0 is oxidized to
Hg2+ by halogens present in/injected on the coal, by an SCR catalyst or through an air pre-heater ahead of
the FGD
• Additionally, ACI (activated carbon injection), e.g. directly into an ESP, removes Hg from the flue via the
same chemi-adsorption principles that bind Hg to the activated carbon in sorbent traps
• High SO2 and PM generally equates to more maintenance/issues for Hg CEMS; systems with PCDs
(especially FGDs) generally require less maintenance
• Hg CEMS use N2 as a diluent requiring (>100psi) for N2 generation further necessitating either air
compressors (and additional maintenance) or a greater burden on plant air
• Probes require high heat for Hg2+ conversion and to ensure that Hg will not bind to components making
probes difficult/tedious/expensive to maintain
• Analyzers require high intensity UV lamps that continue to experience issues and present challenges
• Probe controller components are very susceptible to lightning and power surges
• Hg CEMS may experience considerable downtime and non-availability after maintenance/troubleshooting
while the system ‘settles out’
• Calibrator traceability protocols were created to ensure accurate, NIST traceable, field reference calibrators
• Currently, TMFS calibrators can achieve (down to) 2.5ug/scm limiting system ranges to 0-10ug/scm in
order to accommodate regulatory QA/QC
• Vendors such as Ohio Lumex offer upgrades that will significantly lower MDLs for carbon trap analysis
• Work continues on the development of a portable Hg CEMS and instrumental reference method (30A) that
will allow for real-time and direct comparison of Hg CEMS