THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
&EPA
U.S. Environmental Protection Agency
IGCI
Illinois Clean Coal Institute
Baneiie
The Business oj Innovation
ETV Joint Verification Statement
TECHNOLOGY TYPE: Mercury Emissions Monitor
APPLICATION: Sorbent Trap Monitoring of Flue Gas Mercury
TECHNOLOGY
NAME:
COMPANY:
ADDRESS:
WEB SITE:
E-MAIL:
Sorbent-Based Mercury Sampling System
Apex Instruments, Inc.
204 Technology Park Lane PHONE: (919) 557-7300
Fuquay-Varina, NC 27526 FAX: (919)557-7110
www.apexinst.com/
info@apexinst.com
The U.S. Environmental Protection Agency (EPA) has established the Environmental Technology Verification
(ETV) Program to facilitate the deployment of innovative or improved 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. Information and ETV documents are available at www.epa.gov/etv.
ETV works in partnership with recognized standards and testing organizations, with stakeholder groups
(consisting of buyers, vendor organizations, and permitters), and with 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 Advanced Monitoring Systems (AMS) Center, one of six technology areas under ETV, is operated by
Battelle in cooperation with EPA's National Exposure Research Laboratory. In collaboration with the Illinois
Clean Coal Institute, and with assistance from the Northern Indiana Public Service Company, the AMS Center
evaluated the performance of the Apex Instruments Sorbent-Based Mercury Sampling System for determining
mercury in stack gas at a coal-fired power plant. This verification statement provides a summary of the test
results.
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VERIFICATION TEST DESCRIPTION
The performance of the Apex system was evaluated in terms of relative accuracy (RA), data completeness, and
operational factors (ease of use, maintenance and data output needs, power and other consumables use, reliability,
and operational costs). RA was determined according to Equation A-10 of Chapter 40 of the Code of Federal
Regulations Part 75 (40 CFR Part 75) Appendix A, by comparing the Apex vapor-phase total mercury (HgT)
results to simultaneous results from American Society for Testing and Materials (ASTM) D 6784-02, the
"Ontario Hydro" (OH) method. Data completeness was assessed as the percentage of maximum data return
achieved by the Apex system over its test period. Operational factors were evaluated by means of observations
during use and records of needed maintenance, vendor activities, and expendables use.
The Apex system was verified at Unit 17 of the R.M. Schahfer Generating Station, located near Wheatfield,
Indiana, between July 9 and 13, 2006. Unit 17 burns pulverized Illinois sub-bituminous coal and has an
electrostatic precipitator and a wet flue gas desulfurization unit. During this period, twelve successive OH method
runs, each of 2 hours duration, were conducted on the Unit 17 stack using paired OH trains. Those reference
samples were collected and analyzed to determine elemental mercury and oxidized mercury, the sum of which is
HgT.
QA oversight of verification testing was provided by Battelle and EPA. Battelle QA staff conducted a technical
systems audit, a performance evaluation audit, and a data quality audit of 10% of the test data.
This verification statement, the full report on which it is based, and the test/QA plan for this verification test are
all available atwww.epa.gov/etv/centers/centerl.html.
TECHNOLOGY DESCRIPTION
The following description of the Apex system is based on information provided by the vendor. The
information provided below was not verified in this test.
The Apex system tested in this program was designed to sample mercury emissions from coal-fired sources as
specified in Appendix K in 40 CFR Part 75. The system consisted of two Apex Instruments Model XC-60 Gas
Sampling Consoles, an SGC 4000 Hg Stirling Gas Conditioner, and a 9-foot-long dual trap mercury sampling
probe with a 25-foot-long heated sample line. Each XC-60 console incorporated a dry gas meter, rotameter flow
meter, manual sample flow control valves, temperature indicators, vacuum gauge, and sampling pump. These
consoles performed simultaneous sampling with two sorbent traps through the single probe, maintaining a
constant sampling flow of about 500 cubic centimeters per minute through each trap. Pre- and post-run leak
checks were conducted in each run. Sample gas drawn through the sorbent traps in the probe tip was transported
through the heated sample line to the SGC 4000 Hg Stirling Gas Conditioner, where moisture was removed by
condensation before the gas entered each XC-60 console. The Apex system operator recorded sampling data
manually every 15 minutes during each run, including stack, probe, console, and Stirling chiller temperatures;
sample flow rates; vacuum and pressure readings; and barometric pressure.
The sorbent traps used with the Apex system were prepared and analyzed for HgT by Ohio Lumex. Consistent
with Appendix K, each trap incorporated three sorbent sections: a sampling section, a breakthrough section, and a
pre-spiked section to assess mercury spike recovery.
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VERIFICATION RESULTS
The RA of the Apex system for determining HgT was 26.6%, based on 11 OH runs, when the comparison was
based on Apex results uncorrected for mercury spike recovery. For those 11 runs, the overall average HgT value
from the OH reference method was 1.008 micrograms per dry standard cubic meter ((ig/dscm), whereas that
from the Apex system was 1.171 (ig/dscm, a difference of 0.162 (ig/dscm. When comparing Apex results
corrected for mercury spike recovery, the RA for 11 runs was 20.3%, and the OH and Apex average values were
1.008 (ig/dscm and 1.132 (ig/dscm, respectively, a difference of 0.124 (ig/dscm.
The Apex sampler was operated during all 12 OH runs conducted over four days with no delays or sampling
interruptions. However, the recovery of sorbent traps for analysis was incomplete due to breakage of traps. Both
paired sorbent traps were recovered for seven of the 12 OH runs, one trap was recovered for four runs, and for
the final run only one usable sorbent trap was available. Treating those five runs with only one trap recovered as
one-half of a complete sampling run, the overall data completeness for the Apex sampler is calculated to be
79.2%.
The greatest limitation of the Apex system was the poor quality of the sorbent traps used. The traps were fragile,
and the glass tubing used for the traps was of inconsistent diameter. This made installation and retrieval of the
traps difficult and led to frequent breakage of the traps. It should be noted that this limitation due to the traps is
not related to the Apex sampling technology itself, i.e., improvements in the quality of the sorbent traps should
translate directly into improved performance of the entire system. An additional limitation of the Apex system
was the relatively heavy sampling probe used with the system, which was very difficult for one operator to
handle alone.
The approximate cost of the Apex system as tested (i.e., a manually operated dual system) is $10,000 to $15,000,
depending on options. As used in this test, the cost per sorbent trap sample was $205, consisting of $55 for the
trap, $60 for pre-spiking with mercury, and $90 for analysis of the three-section trap after sampling.
Original signed by Gregory A. Mack 2/16/2007 Original signed by Sally Gutierrez
Gregory A. Mack Date
Vice President
Energy, Transportation, and Environment Division
Battelle
Sally Gutierrez
Director
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
4/4/2007
Date
NOTICE: ETV verifications are based on an evaluation of technology performance under specific,
predetermined criteria and the appropriate quality assurance procedures. EPA and Battelle make no expressed or
implied warranties as to the performance of the technology and do not certify that a technology will always
operate as verified. The end user is solely responsible for complying with any and all applicable federal, state,
and local requirements. Mention of commercial product names does not imply endorsement.
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