February 2007
Environmental Technology
Verification Report
ENVIRONMENTAL SUPPLY COMPANY
HG-324K SORBENT-BASED MERCURY SAMPLING
SYSTEM
Prepared by
Battelle
Banene
The Rnsiness of Innovation
Under a cooperative agreement with
^Sfr QJT\ U.S. Environmental Protection Agency
ET1/ET1/ET1/
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February 2007
Environmental Technology Verification
Report
ETV Advanced Monitoring Systems Center
ENVIRONMENTAL SUPPLY COMPANY
HG-324K SORBENT-BASED MERCURY SAMPLING
SYSTEM
by
Thomas Kelly
Jan Satola
Zachary Willenberg
Amy Dindal
Battelle
Columbus, Ohio 43201
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Notice
The U.S. Environmental Protection Agency (EPA), through its Office of Research and
Development, has financially supported and collaborated in the extramural program described
here. This document has been peer reviewed by the Agency. Mention of trade names or
commercial products does not constitute endorsement or recommendation by the EPA for use.
This report was prepared by Battelle to summarize testing supported in part by the Illinois
Department of Commerce and Economic Opportunity through the Office of Coal Development
and the Illinois Clean Coal Institute (ICCI). Neither Battelle nor any of its subcontractors nor the
Illinois Department of Commerce and Economic Opportunity, Office of Coal Development; the
ICCI; nor any person acting on behalf of either
(a) Makes any warranty of representation, express or implied, with respect to the accuracy,
completeness, or usefulness of the information contained in this report, or that the use of
any information, apparatus, method, or process disclosed in this report may not infringe
privately-owned rights; or
(b) Assumes any liabilities with respect to the use of, or for damages resulting from the use of,
any information, apparatus, method, or process disclosed in this report.
Reference herein to any specific commercial product, process, or service by trade name,
trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement,
recommendation, or favoring; nor do the views and opinions of authors expressed herein
necessarily state or reflect those of the Illinois Department of Commerce and Economic
Opportunity, Office of Coal Development, or the ICCI.
Notice to Journalists and Publishers: If you borrow information from any part of this
report, you must include a statement about the state of Illinois' support of the project.
11
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Foreword
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the
nation's air, water, and land resources. Under a mandate of national environmental laws, the
Agency strives to formulate and implement actions leading to a compatible balance between
human activities and the ability of natural systems to support and nurture life. To meet this
mandate, the EPA's Office of Research and Development provides data and science support that
can be used to solve environmental problems and to build the scientific knowledge base needed
to manage our ecological resources wisely, to understand how pollutants affect our health, and to
prevent or reduce environmental risks.
The Environmental Technology Verification (ETV) Program has been established by the EPA to
verify the performance characteristics of innovative environmental technology across all media
and to report this objective information to permitters, buyers, and users of the technology, thus
substantially accelerating the entrance of new environmental technologies into the marketplace.
Verification organizations oversee and report verification activities based on testing and quality
assurance protocols developed with input from major stakeholders and customer groups
associated with the technology area. ETV consists of six environmental technology centers.
Information about each of these centers can be found on the Internet at http://www.epa.gov/etv/.
Effective verifications of monitoring technologies are needed to assess environmental quality
and to supply cost and performance data to select the most appropriate technology for that
assessment. Under a cooperative agreement, Battelle has received EPA funding to plan,
coordinate, and conduct such verification tests for "Advanced Monitoring Systems for Air,
Water, and Soil" and report the results to the community at large. Information concerning this
specific environmental technology area can be found on the Internet at http://www.epa.gov/etv/
centers/center 1 .html.
in
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Acknowledgments
The authors wish to acknowledge the support of all those who helped plan and conduct the
verification test, analyze the data, and prepare this report. This verification was funded in part by
the Illinois Clean Coal Institute (ICCI) under Project No. 04-1/3.2D-1; we appreciate the
involvement and support of Dr. Francois Botha, Project Manager for the ICCI. We acknowledge
the contribution of the Northern Indiana Public Service Company (NIPSCo, a NiSource
company) in hosting this verification at the R. M. Schahfer Generating Station and, in particular,
the efforts of Craig Myers, Bert Valenkamph, and Gary Logan of NIPSCo in support of the field
testing. We also thank Eric Ginsburg and William Grimley of U.S. EPA for their assistance in
setting up a Site Access Agreement among EPA, Battelle, and NiSource. Finally, we would like
to thank Robin Segall of U.S. EPA, Ernest Bouffard of the Connecticut Department of
Environmental Protection, Francois Botha of ICCI, and Craig Myers of NIPSCo for their review
of this verification report.
IV
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Contents
Notice ii
Foreword iii
Acknowledgments iv
List of Abbreviations vii
Chapter 1 Background 1
Chapter 2 Technology Description 2
Chapters Test Design and Procedures 4
3.1 Introduction 4
3.2 Test Facility 5
3.3 Test Procedures 6
3.3.1 Relative Accuracy 6
3.3.2 Data Completeness 7
3.3.3 Operational Factors 7
3.4 Verification Schedule 7
Chapter 4 Quality Assurance/Quality Control 9
4.1 OH Reference Method 9
4.1.1 OH Reproducibility 9
4.1.2 OH Blank and Spike Results 10
4.2 Audits 11
4.2.1 Performance Evaluation Audits 11
4.2.2 Technical Systems Audit 12
4.2.3 Data Quality Audit 13
4.3 QA/QC Reporting 13
4.4 Data Review 13
Chapters Statistical Methods 14
5.1 Relative Accuracy 14
5.2 Data Completeness 14
Chapter 6 Test Results 15
6.1 Relative Accuracy 15
6.1.1 Relative Accuracy: Uncorrected Data 16
6.1.2 Relative Accuracy: Spike-Corrected Data 17
6.2 Data Completeness 18
6.3 Operational Factors 18
Chapter 7 Performance Summary 19
Chapters References 20
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Figures
Figure 2-1. HG-324K Sorbent Tube Mercury Sampling System 2
Tables
Table 3-1. Operating and Stack Gas Conditions at Schahfer Station Unit 17 6
Table 3-2. Schedule of OH Method Sampling in the Week of June 12, 2006 7
Table 4-1. OH Results from June 12-15,2006, Sampling Period 10
Table 4-2. Summary of PE Audit Results 12
Table 6-1. HG-324K HgT Results 16
Table 6-2. Data Used for Comparison of OH and HG-324K HgT Results 17
Table 6-3. Data Used for Comparison of OH and Spike-Corrected HG-324K HgT Results 17
VI
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List of Abbreviations
agl
AMS
ASTM
CEM
EPA
ETV
FGD
H202
H2SO4
Hg
HgCl2
Hg°
Hgox
HgT
HNO3
ICCI
KC1
klb/hr
KMnO4
L/min
MW
ug/dscm
ug/mL
mL
NIST
NOX
OH
ppm
PE
QA
QC
QMP
RA
RD
above ground level
Advanced Monitoring Systems
American Society for Testing and Materials
continuous emission monitor
U.S. Environmental Protection Agency
Environmental Technology Verification
degrees Fahrenheit
flue gas desulfurization
hydrogen peroxide
sulfuric acid
mercury
mercuric chloride
elemental mercury
oxidized mercury
total mercury
nitric acid
Illinois Clean Coal Institute
potassium chloride
thousands of pounds per hour
potassium permanganate
liters per minute
megawatt
microgram per dry standard cubic meter
microgram per milliliter
milliliter
National Institute of Standards and Technology
nitrogen oxides
Ontario Hydro
part per million
performance evaluation
quality assurance
quality control
quality management plan
relative accuracy
relative deviation
vn
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SO2 sulfur dioxide
TSA technical systems audit
Vlll
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Chapter 1
Background
The U.S. Environmental Protection Agency (EPA) supports the Environmental Technology
Verification (ETV) Program to facilitate the deployment of innovative environmental
technologies through performance verification and dissemination of information. The goal of the
ETV Program is to further environmental protection by accelerating the acceptance and use of
improved and cost-effective technologies. ETV seeks to achieve this goal by providing high-
quality, peer-reviewed data on technology performance to those involved in the design,
distribution, financing, permitting, purchase, and use of environmental technologies.
ETV works in partnership with recognized testing organizations; with stakeholder groups
consisting of buyers, vendor organizations, and permitters; and with the full participation of
individual technology developers. The program evaluates the performance of innovative
technologies by developing test plans that are responsive to the needs of stakeholders,
conducting field or laboratory tests (as appropriate), collecting and analyzing data, and preparing
peer-reviewed reports. All evaluations are conducted in accordance with rigorous quality
assurance (QA) protocols to ensure that data of known and adequate quality are generated and
that the results are defensible.
The EPA's National Exposure Research Laboratory and its verification organization partner,
Battelle, operate the Advanced Monitoring Systems (AMS) Center under ETV. The AMS Center
recently evaluated the performance of the Environmental Supply Company's HG-324K sorbent-
based mercury sampling system for determining mercury in stack gas at a coal-fired power plant.
This evaluation was carried out in collaboration with the Illinois Clean Coal Institute and with
the assistance of the Northern Indiana Public Service Company.
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Chapter 2
Technology Description
The objective of the ETV AMS Center is to verify the performance characteristics of
environmental monitoring technologies for air, water, and soil. This report provides results for
the verification testing of the Environmental Supply Company's HG-324K mercury sampling
system. The following is a description of the HG-324K, based on information provided by the
vendor. The information provided below was not verified in this test.
The HG-324K system (Figure 2-1) was designed to sample mercury emissions from coal-fired
sources as specified in Appendix K in Chapter 40 of the Code of Federal Regulations Part 75
(40 CFR Part 75).(1) The system consists of a dual heated probe, knockout and drying impingers
to remove moisture, a connecting umbilical, and the HG-324K automated sampler. An integrated
sample of vapor phase mercury is captured on two parallel and independent sorbent traps that are
placed in the stack on the front of the sampling probe. Stack gas is drawn through each of the
traps at a constant flow rate of approximately 500 cubic centimeters per minute. The traps and
probe are heated to prevent condensation of moisture from the sample gas. After exiting the
probe, the sample gas passes through the knockout and drying impingers to remove moisture and
then is drawn into the HG-324K sampler for
measurement of the sample volume. The HG-
324K provides proportional, integral, derivative
flow control of the dual samples; records all
temperatures including the stack, probe, and
condenser; controls the probe temperature; and
measures the dry standard volume of sample gas.
The mass of mercury is determined using cold
vapor atomic fluorescence spectrometry as
specified in EPA Method 1631 .(2) For quality
control, each trap has a breakthrough section and
a spike and recovery section. The concentration
of vapor phase mercury in the stack is determined
based on the mass of mercury captured on the
sorbent trap and the dry standard stack gas
volume measured by the HG-324K.
The HG-324K is controlled using an industrial
data acquisition and control system with a
removable CompactFlash™ memory card for
storing data files. The HG-324K may be
2
Figure 2-1. HG-324K Sorbent Tube
Mercury Sampling System
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connected to a plant network through wireless or direct connection to allow program control and
remote data access. It comes in a watertight, corrosion proof case with 2-inch hard rubber
transport wheels and a retractable extension handle. The outside dimensions are 24-5/8 inches
long by 19-1/2 inches wide by 14 inches deep.
The list price for the automated sampler is $18,750. The sorbent traps used with the HG-324K in
this test were prepared and analyzed by Frontier Geosciences, of Seattle, Washington. As used in
this test, the cost per sorbent trap sample was about $500, including preparation of the trap, pre-
spiking with mercury, and analyzing the trap for mercury after sampling.
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Chapter 3
Test Design and Procedures
3.1 Introduction
This verification test was conducted according to procedures specified in the Test/QA Plan for
Verification of Continuous Emission Monitors (CEMs) and Sorbent-Based Samplers for Mercury
at a Coal-Fired Power Plant^ Appendix K of 40 CFR Part 75(1) establishes sorbent-based
sampling systems as an acceptable approach for determining mercury in the stack gas of utility
generating stations. Such sorbent-based systems collect integrated samples of mercury from
stack gas onto selective sorbent materials over extended time periods (from a few hours to
several days). The collected samples are then analyzed for mercury, and the stack gas mercury
concentration is calculated. Appendix K defines procedures for use of such systems to collect
total vapor-phase mercury in combustion source emissions and requires the use of multi-stage
sorbent traps pre-spiked with mercury as a quality assurance (QA) measure. In the test reported
here, the HG-324K was verified for measurement of total vapor-phase mercury (HgT), which is
the sum of elemental mercury (Hg°) and oxidized mercury (Hgox) (which is primarily mercuric
chloride [HgCb]) vapors. Note that the HG-324K is a sample collection system; the mercury
results shown from the HG-324K in this report resulted from use of the HG-324K with sorbent
traps prepared and subsequently analyzed for mercury by Frontier Geosciences.
The HG-324K was verified by evaluating the following parameters:
• Relative accuracy (RA)
• Data completeness
• Operational factors such as ease of use, maintenance and data output needs, power and other
consumables use, reliability, and operational costs.
The HG-324K was verified during part of a field test that lasted from June 12 to July 25, 2006,
and that included two separate four-day periods of reference mercury measurements carried out
by ARCADIS Inc., under subcontract to Battelle, using American Society for Testing and
Materials (ASTM) D 6784-02, the "Ontario Hydro" (OH) method.(4) Specifically, the HG-324K
was used to sample stack gas from June 12 through June 15, 2006, and RA was determined by
comparing HG-324K vapor-phase mercury results to simultaneous results from 12 two-hour
sampling runs with the OH method. Data completeness was assessed as the percentage of
maximum data return achieved by the HG-324K over its test period. Operational factors were
evaluated by means of operator observations and records of needed maintenance, vendor
activities, and expendables use.
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The sorbent traps used with the HG-324K for this verification were prepared, and subsequently
analyzed for mercury after sampling, by Frontier Geosciences. The traps each contained four
separate sections of sorbent. The first section collected mercury from the flue gas; the second
collected any breakthrough from the first section; the third was spiked, as required by
Appendix K(1), with mercury before sampling; and the fourth collected any mercury lost from the
third section during sampling. Trap preparation included spiking the third sorbent section of each
trap with nominally 100 ng of mercury. Spike recovery determinations were not based on this
nominal value, however. Frontier Geosciences determined the true value of the mercury spike
amount as 98.47 ng, by retaining a subset of spiked traps in the laboratory, and determining the
amount of mercury on the spiked section of the traps at the same time that the collected samples
from this field verification of the HG-324K were analyzed. The mercury analysis by Frontier
Geosciences included measurement of mercury on each of the four sorbent stages in each trap,
analysis of blank traps, analysis of a mercury Standard Reference Material® (National Institute of
Standards and Technology [NIST] 164Id), assessment of analytical spike recovery and replicate
analysis precision, and analysis of initial and continued calibration blank and continued
calibration verification samples.
3.2 Test Facility
The host facility for the HG-324K verification was the R.M. Schahfer Generating Station,
located near Wheatfield, Indiana, approximately 20 miles south of Valparaiso, Indiana. The
Schahfer plant consists of four units (designated 14, 15, 17, and 18), with a total rated capacity of
about 1,800 megawatts (MW). The HG-324K was verified at Unit 17, which burns pulverized
Illinois sub-bituminous coal and has an electrostatic precipitator and a wet flue gas
desulfurization (FGD) unit. Unit 17 has a typical capacity of about 380 MW. The unit was
operated near this capacity for most of the test period, although the typical daily pattern of
operation was to reduce load substantially for a few hours between late evening and early
morning.
Flue gas from Unit 17 feeds into a free-standing concrete chimney with an internal liner. The top
of the stack is 499 feet above ground level (agl). Emission test ports and penetrations in the
concrete chimney and liner are located at a platform approximately 8 feet wide that encircles the
outside of the stack at 370 feet agl. The stack diameter at the platform level is 22 feet 6 inches, so
the total flow area is 397.6 square feet. The last flow disturbance is at the FGD connection to the
stack liner at 128 feet agl. Thus, the emission test ports were over 10 stack diameters down-
stream from the last flow disturbance and nearly six diameters upstream from the stack exit. Four
emission test ports were located at 90° intervals around the circumference of the stack about
4 feet above the platform at 370 feet agl and were standard 4-inch ports with #125 flanges. No
traversing was done during sampling; both the OH method and the HG-324K sampled from a
single fixed point one meter inside the inner liner of the stack at their respective port locations.
This arrangement was justified by the absence of stratification observed for sulfur dioxide (862)
and nitrogen oxides (NOx) at this sampling location.
Table 3-1 summarizes key operating and stack gas conditions that characterize Schahfer Unit 17
during the field period, showing the range and average values of key parameters and
constituents. Stack gas pressure was slightly positive at the sampling location.
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Table 3-1. Operating and Stack Gas Conditions at Schahfer Station Unit 17
Parameter
Unitl7Loada
Coal Feed Ratea
Temperature21
Moistureb
N0xa
S02a
Total mercury vaporb
Average
334 MW
297 klb/hrc
130°F
14.8 %
97 ppmd
193 ppm
0.81 ug/dscme
Range
140-391
140-374
118-140
13.3-15.3
61-165
104-316
0.73-0.93
a: Values calculated from hourly data recorded by R.M. Schahfer staff June 12 to July 25, 2006.
b: Values based on measurements made during OH reference sampling periods June 12-15, 2006.
c: klb/hr = thousands of pounds per hour.
d: ppm = parts per million.
e: ug/dscm = micrograms per dry standard cubic meter.
3.3 Test Procedures
Following are the test procedures used to evaluate the HG-324K.
3.3.1 Relative A ccuracy
The RA of the HG-324K was evaluated by comparing its Hgx results to simultaneous results
obtained by sampling stack gas with the OH method. The OH method is the currently accepted
reference method for mercury measurements in stack gas, and employs dual impinger trains
sampling in parallel through a common probe to determine oxidized and elemental vapor-phase
mercury by means of appropriate chemical reagents.(4) Over the period of June 12 to 15,
ARCADIS conducted a series of 12 OH runs on the Unit 17 stack, each two hours in duration,
using paired OH trains. The HgT concentration determined by the OH reference method in each
run was compared to the corresponding result from paired HG-324K traps sampled over exactly
the same time period as the OH run.
The OH trains were dismantled for sample recovery in the field by ARCADIS staff, and all
collected sample fractions were logged and stored for transfer to the ARCADIS analytical
laboratory. All sample handling, quality assurance/quality (QA/QC) activities, and mercury
analyses were conducted by ARCADIS. Subsequent to mercury analysis, ARCADIS reviewed
the data and reported final mercury results from all trains in units of ug/dscm. The results from
the paired OH trains were checked relative to the duplicate precision criterion required of the OH
method,(5) and qualified OH results were averaged to produce the final reference data. The paired
sorbent trap samples collected using the HG-324K were sent to Frontier Geosciences in Seattle,
Washington, for mercury analysis. The mercury results from the paired HG-324K sorbent traps
were reviewed for spike recovery and duplicate precision relative to Appendix K requirements.(1)
RA was calculated as described in Section 5.1, and in addition the average of all HG-324K
results was compared to the average of all OH results.
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3.3.2 Data Completeness
No additional test procedures were carried out specifically to address data completeness of the
HG-324K. This parameter was assessed by comparing the overall data return to the total possible
data return.
3.3.3 Operational Factors
Operational factors such as maintenance needs, data output, consumables use, and ease of use
were evaluated based on observations by Battelle and Schahfer facility staff. Examples of
information used to assess operational factors were the use or replacement of any consumables,
the effort or cost associated with maintenance or repair, vendor effort (e.g., time on site) for
repair or maintenance, the duration and causes of any down time or data acquisition failure, and
observations about ease of use of the HG-324K.
3.4 Verification Schedule
The HG-324K was verified in a field effort that took place from June 12 to July 25, 2006, that
also evaluated two mercury CEMs and one other sorbent-based system. The HG-324K was
installed at the Unit 17 stack on June 11 and removed on June 16, 2006, during which period it
was operated by a vendor representative. Twelve successive OH reference method runs were
carried out in this period for comparison to the HG-324K results.
Table 3-2 shows the actual schedule of OH reference method sampling completed by ARCADIS
between June 12 and 15, 2006. The OH sampling proceeded efficiently, with three runs
conducted on each of four successive days. In all cases, the HG-324K vendor representative was
informed of the planned start time of each OH run; and, in a few instances, the start time of a run
was delayed slightly to assure that the technologies being tested were fully ready to obtain data
during the OH run. All OH runs were of exactly two hours duration.
Table 3-2. Schedule of OH Method Sampling in the Week of June 12, 2006
Run Number
1
2
3
4
5
6
7
8
9
10
11
12
Date
6/12/06
6/12/06
6/12/06
6/13/06
6/13/06
6/13/06
6/14/06
6/14/06
6/14/06
6/15/06
6/15/06
6/15/06
Start Time
09:15
12:15
15:40
08:15
11:10
14:05
08:10
11:25
14:30
08:20
11:05
13:45
End Time
11:15
14:15
17:40
10:15
13:10
16:05
10:10
13:25
16:30
10:20
13:05
15:45
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Following the field sampling effort, all HG-324K sorbent trap samples were shipped by
Environmental Supply Company to Frontier Geosciences for analysis. Frontier Geosciences
returned an analysis data file that included results of blank, replicate analysis, and other QA/QC
results, along with the calculated stack gas mercury concentrations from each sorbent trap both
uncorrected and corrected for mercury spike recovery.
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Chapter 4
Quality Assurance/Quality Control
QA/QC procedures were performed in accordance with the quality management plan (QMP) for
the AMS Center(6) and the test/QA plan for this verification test.(3) QA/QC procedures and
results are described below.
4.1 OH Reference Method
This verification test included a comparison of HG-324K results to those of the OH reference
method for flue gas mercury.(4) The quality of the reference measurements was assured by
adherence to the requirements of the OH method, including requirements for solution and field
blanks, spiked samples, and initial and continuing blanks and calibration standards. In addition,
all OH reference measurements were made with paired trains, and the percent relative deviation
(%RD) of each data pair was required to be < 10% (at mercury levels >1.0 ug/dscm) or < 20%
(at mercury levels < 1.0 ug/dscm) (%RD = difference between the paired train results divided by
sum of those results, expressed as a percentage).(5) The following sections present key data
quality results from the OH method.
4.1.1 OH Reproducibittty
The mercury results of the OH stack gas samples are shown in Table 4-1 for the June 12 to 15
period of OH method sampling. The table indicates the OH run number, and lists the average
vapor phase Hgox, Hg°, and HgT results from the paired OH trains in each run, and the percent
relative deviation of each pair of results. All mercury results are in micrograms of mercury per
dry standard cubic meter (ug/dscm).
Inspection of Table 4-1 shows that HgT in the Unit 17 stack ranged from 0.73 to 0.93 ug/dscm in
the OH runs conducted in the June 12-15 period. The average HgT value was 0.81 ug/dscm. Hg°
comprised the great majority of the HgT, consistent with the scrubbing of the Schahfer Unit 17
flue gas. Hgox never exceeded about 0.07 ug/dscm and was typically about 5% of the HgT.
Table 4-1 shows close agreement between the paired OH train results for all three mercury
fractions. The %RD values in Table 4-1 are less than about 5% in all 12 runs for both Hg° and
Hgx. The %RD values for the relatively very low Hgox concentrations are slightly higher, with
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Table 4-1. OH Results from June 12-15, 2006, Sampling Period
Average Mercury Concentration (^ig/dscm) and %RD of Paired Train Results'
,00
OH Run
1
2
3
4
5
6
7
8
9
10
11
12
Hgox
0.022
0.037
0.038
0.058
0.053
0.048
0.072
0.060
0.055
0.054
0.037
0.032
%RD
15.3
6.8
3.9
3.4
6.6
11.4
1.2
0.5
5.0
0.2
2.5
1.8
Kg"
0.762
0.822
0.821
0.875
0.795
0.684
0.739
0.690
0.819
0.766
0.691
0.748
%RD
3.6
3.8
1.1
2.0
0.6
4.9
2.1
4.3
1.9
3.9
1.1
2.4
HgT
0.783
0.859
0.859
0.933
0.848
0.732
0.811
0.750
0.874
0.820
0.727
0.781
%RD
3.0
3.4
0.9
1.7
0.1
5.3
2.0
3.9
1.5
3.6
0.9
2.4
(a) o,
%RD = difference between paired train results divided by sum of paired train results.
two values exceeding 10%. The applicable acceptance criterion for all the paired OH results is
%RD < 20%, because all OH mercury results from this set of OH runs were less than
1 ug/dscm.(5) All results in Table 4-1 met that criterion, even for the Hgox fraction, which was
present at very low concentrations.
4.1.2 OH Blank and Spike Results
Analyses were conducted on eight total samples collected at the Schahfer site from the blank
reagents used in the OH method between June 12 and 15. Only two of those samples showed
detectable mercury, with concentrations of 0.004 ug/L. This blank reagent concentration is
negligible compared to the mercury in impinger solutions recovered from trains after stack
sampling. Those recovered sample concentrations were typically about 0.1 ug/L, 0.2 ug/L, and
3 ug/L in potassium chloride (KC1) solution, hydrogen peroxide (H2O2) solution, and potassium
permanganate (KMnO4) solution, respectively.
Blank OH sampling trains were prepared and taken to the sampling location on the Unit 17 stack
on three occasions in the period of OH sampling and were then returned for sample recovery
without exposure to stack gas. These blank OH trains provide additional assurance of the quality
of the train preparation and recovery steps. For the June 12 to 15 sampling period, the total
amounts of mercury recovered from the three blank trains range from 0.126 to 0.144 ug,
equivalent to approximately 7% of the typical total amount of mercury recovered from a train
after stack sampling at the Schahfer plant. Those blank train results correspond to stack gas
mercury concentrations of less than 0.06 ug/dscm under typical sampling conditions in this
verification.
All initial and continuing blank and calibration values from laboratory analysis of the OH
samples met the requirements of the OH method. The recovery of mercury spiked into each
reagent solution recovered from blank and sampled OH trains was also evaluated during
laboratory analysis. Those spike recoveries ranged from 85 to 112%, and averaged 93%. The
recovery of mercury spiked into blank train samples as part of the performance evaluation (PE)
audit also met the prescribed criteria, as described in Section 4.2.1.
10
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4.2 Audits
Three types of audits were performed during the verification test: a PE audit of the OH reference
method, a technical systems audit (ISA) of the verification test performance, and a data quality
audit. Audit procedures are described further below.
4.2.1 Performance Evaluation Audits
PE audits of the OH method were carried out through procedures implemented at the Schahfer
plant during the field period. Table 4-2 summarizes the procedures and results of the PE audits of
the OH reference method, showing the parameter audited, the date of the audit, the OH and
reference values, the observed agreement, and the target agreement. The OH method
incorporates dual sampling trains, and the equipment used by ARCADIS to carry out the OH
sampling included dual Model 522 Source Sampler meter boxes (Apex Instruments, Fuquay-
Varina, North Carolina) designated by serial number as #2007 and #2008. As a result, for some
parameters, Table 4-2 includes results for both meter boxes or for both of the dual OH trains.
Four PE audits were conducted:
• A Fluke Model 52 II digital thermometer (Serial No. 80730162) was used to audit the probe
temperature measurements made by the #2007 meter box and the stack temperature
measurements made by the #2008 meter box. For this comparison, the appropriate
thermocouple was disconnected from the meter box and connected to the Fluke thermometer.
• A BIOS International Corporation DryCal NIST-traceable flow measurement standard
(Model DC2-B, Serial No. 103777, vendor-calibrated on May 9, 2006) was used to audit the
sample gas flow rate with each of the two OH meter boxes. Note that this audit was
conducted during a second period of OH sampling carried out in this verification test in July
2006, rather than in the June 12 to!5 period used for verification of the HG-324K.
• A set of weights (Rice Lake Weight Set, Serial No. 1JXA) calibrated to ASTM Class 3
standards was used to audit the electronic balance (AND FP-6000, Serial No. 6402118) used
for weighing the OH method impingers.
• Recovery of mercury from OH trains was audited by spiking impingers containing KC1,
H2O2/nitric acid (HNOs), and KMnOVsulfuric acid (H2SO4) reagents in two blank OH
impinger trains, with 1 milliliter (mL) of a prepared mercury solution, in each of the two
separate periods of OH sampling. The mercury spiking solution was 2.5 ug/mL Hg in 1%
HNOs and was prepared by dilution of a NIST-traceable 1,000-ppm (i.e., 1,000-ug/mL)
standard (Aa34n-l, Accustandards, Inc.). In the first week of OH sampling, Impingers 2, 4,
and 5 of Blank Trains 8L and 8R were spiked; and, in the final week of OH sampling,
Impingers 2, 4, and 6 of Blank Trains 7L and 7R were spiked.
Table 4-2 shows that all the PE audit results were within the target tolerances set in the test/QA
plan.(3)
11
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Table 4-2. Summary of PE Audit Results
Parameter
OH temperature
measurement
OH sample flow
measurement
Impinger weighing
Mercury spike
recovery
Date
6/14/06
probe T
stack T
7/11/06
6/14/06
6/14/06
train 8L
imp 2
imp 4
imp 5
train 8R
imp 2
imp 4
imp 5
7/12/06
train 7L
imp 2
imp 4
imp 6
train 7R
imp 2
imp 4
imp 6
OH Result
228°F(a)
127oF(b)
15.02L/min(a)
14.58 L/min(b)
199.72
499.27
2.48 ug
2.02 ug
2.08 ug
2.47 ug
1.97ug
2.10ug
2.24 ug
2.12 ug
2.38 ug
2.27 ug
2.33 ug
2.39 ug
Reference
Value
230°F
129°F
14.56 L/min
14.35 L/min
200 grams
500 grams
2.5 ug
2.5 ug
2.5 ug
2.5 ug
2.5 ug
2.5 ug
2.5 ug
2.5 ug
2.5 ug
2.5 ug
2.5 ug
2.5 ug
Observed
Agreement
0.29%
0.31%
3.2%
1.6%
0.14%
0.15%
0.8%
19.2%
16.8%
1.2%
21.2%
16.0%
10.4%
15.2%
4.8%
9.2%
6.8%
4.4%
Target
Agreement
2% absolute T
5%
Greater of 1%
or 0.5 gram
25%
25%
25%
25%
25%
25%
25%
25%
25%
25%
25%
25%
(a) #2007 meter box.
(b) #2008 meter box.
L/min = liters per minute; T = temperature; imp = impinger.
4.2.2 Technical Systems A udit
A Battelle Quality Management representative conducted a TSA at the Schahfer test site on
June 14 to ensure that the verification test was being conducted in accordance with the test/QA
plan(3) and the AMS Center QMP.(6) As part of the TSA, test procedures were compared to those
specified in the test/QA plan,(3) and data acquisition and handling procedures, as well as the
reference standards and method were reviewed. The Quality Management representative
observed OH method sampling and sample recovery processes, interviewed ARCADIS
personnel, and observed the PE audit procedures noted above, except for the OH sample flow
and second OH train spiking audits, which were conducted at a later date. Observations and
findings from the TSA were documented and submitted to the Battelle Verification Test
Coordinator for response. None of the findings of the TSA at the Schahfer site required
corrective action. In addition, an internal TSA was conducted in the laboratory charged with
analyzing the OH samples. This TSA was conducted by the ARCADIS independent QA Officer
in the laboratory on-site at EPA in Research Triangle Park, North Carolina, on July 19 and
July 27, 2006. None of the findings of this laboratory TSA required corrective action. Records
from both TSA efforts are permanently stored with the Battelle Quality Manager.
12
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4.2.3 Data Quality Audit
At least 10% of the data acquired during the verification test were audited. Battelle's Quality
Manager traced the data from the initial acquisition, through reduction and statistical analysis, to
final reporting to ensure the integrity of the reported results. All calculations performed on the
data undergoing the audit were checked.
4.3 QA/QC Reporting
Each audit was documented in accordance with Sections 3.3.4 and 3.3.5 of the QMP for the ETV
AMS Center.(6) Once the audit reports were prepared, the Battelle Verification Test Coordinator
ensured that a response was provided for each adverse finding or potential problem and imple-
mented any necessary follow-up corrective action. The Battelle Quality Manager ensured that
follow-up corrective action was taken. The results of the TSA were submitted to the EPA.
4.4 Data Review
Records generated in the verification test received a one-over-one review before these records
were used to calculate, evaluate, or report verification results. Data were reviewed by a Battelle
technical staff member involved in the verification test. The person performing the review added
his/her initials and the date to a hard copy of the record being reviewed.
13
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Chapter 5
Statistical Methods
The statistical methods used to evaluate the quantitative performance factors listed in Section 3.1
are presented in this chapter. Qualitative observations were also used to evaluate verification test
data.
5.1 Relative Accuracy
The RA of the HG-324K with respect to the OH reference method results was assessed as a
percentage, using Equation 1:
d
RA =
ln-\
where Prefers to the difference between the OH reference mercury concentration and the HG-
324K result over the OH sampling period, and x corresponds to the OH reference mercury
concentration. Sd denotes the sample standard deviation of the differences, while tan_i is the t
value for the 100(1 - a)th percentile of the distribution with n-1 degrees of freedom. The RA was
determined for an a value of 0.025 (i.e., 97.5% confidence level, one-tailed). RA was calculated
only for total vapor-phase mercury. All paired OH data meeting the method quality criteria were
eligible for inclusion in the calculation of RA. All 12 OH runs met the quality criteria and were
included in the RA calculation for the HG-324K. A RA of less than 20% is considered
acceptable.(1) Alternatively, when the mean reference mercury level is less than 5.0 jig/dscm (as
in this test), agreement of the overall average HG-324K value within 1.0 jig/dscm of the mean
OH value is also considered acceptable.(1)
5.2 Data Completeness
Data completeness was calculated as the percentage of the total possible data return that was
achieved by the HG-324K over its several days of operation in the field. The primary form of
data completeness was the number of OH runs (out of 12) for which HG-324K produced valid
data. In addition, any down time when the HG-324K would not have been available to carry out
a measurement was judged as incomplete data. The causes of any substantial incompleteness of
data were established from operator observations or vendor records.
14
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Chapter 6
Test Results
The results of the verification tests of the HG-324K sorbent-based sampling system are presented
below for each of the performance parameters.
6.1 Relative Accuracy
The RA of the HG-324K with respect to the OH results for HgT was calculated using Equation 1
in Chapter 5. The primary calculation of RA was conducted using the data from all collected
HG-324K sorbent samples. In addition, RA was calculated after applying the acceptance criteria
and spike recovery correction required under Appendix K(1) to the HG-324K sorbent trap results.
These additional calculations were made to illustrate the impact on RA results if these criteria
were applied.
Table 6-1 summarizes the results obtained from the HG-324K sorbent sampling system.
Table 6-1 lists the date, run number, and trap number of each HG-324K sorbent sample; the
blank-corrected HgT concentration in stack gas determined by each of the sorbent traps; and the
corresponding average concentration of each pair of traps. Also shown are the spike recovery
percentage found for each trap; the HgT concentration that results from applying the spike
recovery correction to each trap as indicated in Appendix K;(1) the corresponding average spike-
corrected concentration of each pair of traps; and the percent relative difference of the spike-
corrected paired trap results.
Table 6-1 shows that the HgT results from paired sorbent traps were generally closely similar,
with the exception of the results from Run 8. In that run the HG-324K post-test leak check failed,
and thus the results from Run 8 are excluded from comparison to the OH results. Table 6-1 also
shows the spike recovery percentage for each trap, and indicates that this percentage was outside
the acceptable range of 75 to 125% for three traps. The results from those traps are also excluded
from comparisons of the spike-corrected HG-324K results to the OH results, in Section 6.1.2. It
is noteworthy that those paired traps exhibiting substantial differences in mercury spike recovery
did not exhibit comparable differences in the measured HgT concentration in the stack before
correction for spike recovery (see Runs 1,3, and 10 in Table 6-1).
The amount of mercury found on the second sorbent section of each HG-324K trap never
exceeded 2% of the amount found on the corresponding first sorbent section. As a result, all the
HG-324K samples met the 5% mercury breakthrough criterion stated in Appendix K.(1)
15
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Table 6-1. HG-324K HgT Results
Date/Run/Trap
6/12/06 Rl Tl
6/12/06 Rl T2
6/12/06 R2 Tl
6/12/06 R2 T2
6/12/06 R3 Tl
6/12/06 R3 T2
6/13/06 R4 Tl
6/13/06 R4 T2
6/13/06 R5 Tl
6/13/06 R5 T2
6/13/06 R6 Tl
6/13/06 R6 T2
6/14/06 R7 Tl
6/14/06 R7 T2
6/14/06 R8 Tl
6/14/06 R8 T2
6/14/06 R9 Tl
6/14/06 R9 T2
6/15/06 RIO Tl
6/15/06 RIO T2
6/15/06 R11T1
6/1 5/06 R11T2
6/15/06 R12 Tl
6/15/06 R12 T2
HgTa
(jig/dscm)
1.045
1.125
1.021
1.076
1.071
1.092
1.178
1.252
1.082
1.082
1.095
0.943
0.918
0.895
1.453
0.875
0.962
0.944
0.932
0.869
0.793
0.860
0.825
1.029
Pair Avg
HgT
(jig/dscm)
1.085
1.049
1.081
1.215
1.082
1.019
0.906
f
0.953
0.901
0.827
0.927
Spike-
% Spike Corrected HgT
Recovery (jig/dscm)b
67.7%
93.1%
95.1%
97.9%
64.1%
101.0%
99.2%
101.6%
102.8%
97.6%
96.3%
100.9%
94.2%
99.8%
87.0%
90.2%
73.8%
95.3%
79.7%
83.4%
84.9%
89.2%
d
1.209
1.074
1.100
d
1.081
1.188
1.232
1.053
1.110
1.138
0.934
0.974
0.897
1.107
1.047
d
0.912
0.995
1.031
0.972
1.154
Pair Avg Spike-
Corrected HgT
(jig/dscm) %RDC
1.209
1.087
1.081
1.210
1.081
1.036
0.936
1.077
0.912
1.013
1.063
e
1.2%
e
1.8%
2.6%
9.8%
4.1%
2.8%
e
1.8%
8.5%
a: Results corrected for average blank trap Hg result.
b: Spike-corrected result = (HgT/% Spike Recovery) x 100.
c: %RD (percent relative deviation) = 100 x absolute value of (T1-T2)/(T1+T2).
d: Spike recovery less than 75%, data excluded per Appendix K.
e: Only one valid result, %RD not calculated.
f: Post-check leak test failed, data excluded.
6.1.1 Relative Accuracy: Unconnected Data
Table 6-2 lists the HgT results in ug/dscm from the OH method (see Table 4-1) and the HG-324K
(see Table 6-1, third column), for OH runs 1 through 7 and 9 through 12; Run 8 is excluded
because of the failed leak test. The RA of the HG-324K based on 11 runs using the uncorrected
data is 29.5 %. Also for these 11 runs, the overall average HgT value from the OH reference
method is 0.821 jig/dscm, whereas the uncorrected HG-324K average is 1.004 jig/dscm, a
difference of 0.183 jig/dscm.
16
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Table 6-2. Data Used for Comparison of OH and HG-324K HgT Results
Date
6/12/06
6/12/06
6/12/06
6/13/06
6/13/06
6/13/06
6/14/06
6/14/06
6/15/06
6/15/06
6/15/06
OH Run
No.a
1
2
3
4
5
6
7
9
10
11
12
OH Hgx
(ug/dscm)
0.783
0.859
0.859
0.933
0.848
0.732
0.811
0.874
0.820
0.727
0.781
HG-324K Hgx,
(ug/dscm)
1.085
1.049
1.081
1.215
1.082
1.019
0.906
0.953
0.901
0.827
0.927
a: Run 8 excluded from calculation because HG-324K failed post-sampling leak check in that ran.
6.1.2 Relative Accuracy: Spike-Corrected Data
Table 6-3 lists the HgT results in ug/dscm from the OH method (see Table 4-1) and the spike-
corrected results in ug/dscm from the HG-324K (see Table 6-1), for OH runs 1 through 7 and 9
through 12; Run 8 is excluded because of the failed leak test. Table 6-3 also notes which three
HG-324K results are from a single trap, as opposed to the average of paired traps, due to low
spike recovery on one trap. The RA of the HG-324K based on these 11 runs using the spike-
corrected data is 37.0 %. Also for these 11 runs, the overall average HgT value from the OH
reference method is 0.821 jig/dscm, whereas the spike-corrected HG-324K average is
1.064 ug/dscm, a difference of 0.243 jig/dscm.
Table 6-3. Data Used for Comparison of OH and Spike-Corrected HG-324K HgT Results"
Date
6/12/06
6/12/06
6/12/06
6/13/06
6/13/06
6/13/06
6/14/06
6/14/06
6/15/06
6/15/06
6/15/06
OH Run
No.a
1
2
3
4
5
6
7
9
10
11
12
OH HgT
(^g/dscni)
0.783
0.859
0.859
0.933
0.848
0.732
0.811
0.874
0.820
0.727
0.781
Spike-Corrected
HG-324K HgT
(^g/dscni)
1.209b
1.087
1.081b
1.210
1.081
1.036
0.936
1.077
0.912b
1.013
1.063
a: Run 8 excluded from calculation because HG-324K failed post-sampling leak check in that ran.
b: Low spike recovery from one trap; therefore, this result from a single trap; all others from paired traps.
17
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The paired trap precision requirement of <10% RD stated in Appendix K(2) was met in the eight
valid HG-324K runs in which spike-corrected paired trap results were obtained (see Table 6-1,
last column). However, eight runs is below the nine values needed to calculate RA, so that
calculation was not done using only the spike-corrected paired trap results.
6.2 Data Completeness
The HG-324K sampled during all 12 of the OH runs conducted June 12-15, 2006, with no
delays, breakdowns, or sampling interruptions. All sorbent traps were recovered after sampling,
with no broken traps. However, after OH Run 8, the post-test leak check failed; and, as a result,
only 11 of the 12 sampling runs (91.7%) were suitable for comparison to the OH reference
results.
6.3 Operational Factors
The HG-324K was installed quickly at the Schahfer Unit 17 stack on June 11 and was operated
by one vendor representative without serious problems for the subsequent four days of OH
reference method sampling. A single failed post-test leak check was the only difficulty
encountered over all 12 OH runs. Ease of use was not investigated with a newly trained operator,
as the vendor operated the HG-324K during the test period. The sorbent traps obtained from
Frontier Geosciences were rugged and uniform in construction, so that no breakage occurred;
and no problems were encountered in placing the traps into the end of the sampling probe or
recovering them after sampling. The sampling probe used with the HG-324K was simple and
relatively light in weight, and was handled by the one vendor operator in all sampling. The HG-
324K sorbent sampling system incorporated the usual capabilities of a stack sampling box, but
also included data acquisition and transfer capabilities. Those capabilities included wireless
communication with a personal computer over distances up to several hundred feet, which
allowed review and transfer of the sampling data at any time without interrupting the sampling
itself. Data were recorded on magnetic card media in the HG-324K, providing a readily
transportable and reliable means of data storage.
18
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Chapter 7
Performance Summary
The RA of the HG-324K for determining HgT based on 11 OH runs was 29.5%, when the
comparison was based on HG-324K results corrected for trap blanks but not corrected for
mercury spike recovery. For those 11 runs, the overall average Hgx value from the OH reference
method was 0.821 jig/dscm, whereas that from the HG-324K was 1.004 jig/dscm, a difference of
0.183 jig/dscm. When comparing HG-324K results corrected for mercury spike recovery, the RA
for 11 OH runs was 37.0%, and the OH and HG-324K average values were 0.821 jig/dscm and
1.064 jig/dscm, respectively, a difference of 0.243 jig/dscm.
The HG-324K sampled during all 12 OH runs conducted over four days with no delays,
breakdowns, broken traps, or sampling interruptions. The only problem encountered was that
after Run 8 the post-test leak check failed. As a result, only 11 of the 12 sampling runs (91.7%
data completeness) were suitable for comparison to the OH reference results.
The HG-324K was installed quickly and was operated by a vendor representative without serious
problems. A failed post-test leak check in one sampling run was the only difficulty encountered.
The sorbent traps were rugged and uniform in construction, so that no breakage occurred; no
problems were encountered in placing the traps into the end of the sampling probe or recovering
them after sampling. The sampling probe used with the HG-324K was simple and relatively light
in weight, and was handled by the one vendor operator in all sampling. The HG-324K sorbent
sampling system incorporated data acquisition and transfer capabilities, including magnetic card
recording media and wireless communication.
The cost of the HG-324K system as tested is $18,750. The cost of each sorbent trap sample was
about $500, including preparation and pre-spiking of the trap, and analysis for mercury after
sampling.
19
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Chapter 8
References
1. Code of Federal Regulations, 40 CFR part 75, including Appendices A through K, July
2005.
2. EPA Method 1631, Revision E: Mercury in Water by Oxidation, Purge and Trap, and Cold
Vapor Atomic Fluorescence Spectrometry, EPA-821-R-02-019, August 2002.
3. Test/QA Plan for Verification of Continuous Emission Monitors and Sorbent-Based
Samplers for Mercury at a Coal-Fired Power Plant, Battelle, Columbus, Ohio, May 18,
2006.
4. Standard Test Method for Elemental, Oxidized, Particle-Bound and Total Mercury in Flue
Gas Generated from Coal-fired Stationary Sources (Ontario Hydro Method), ASTM D
6784-02, American Society for Testing and Materials, West Conshohocken, PA, June 2002.
5. Performance Specification 12A - Specifications and Test Procedures for Total Vapor Phase
Mercury Continuous Emission Monitoring Systems in Stationary Sources, 40 CFR Part 60
Appendix B, July 2005.
6. Quality Management Plan (QMP) for the ETV Advanced Monitoring Systems Center,
Version 6.0, U.S. EPA Environmental Technology Verification Program, Battelle,
Columbus, Ohio, November 2005.
20
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