THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
vxEPA
• «tal Pratectin Agncy
Batreiie
I he Business of Innovation
TECHNOLOGY TYPE: CAVITY RING-DOWN SPECTROSCOPY
APPLICATION:
MEASUREMENT OF AMMONIA SLIP IN STACK GAS
TECHNOLOGY NAME: Model GllOS-c
COMPANY:
ADDRESS:
WEB SITE:
E-MAIL:
Picarro
480 Oakmead Parkway
Sunnyvale, CA 94085
http://www.picarro.com/
rella@picarro.com
PHONE: (408) 962-3900
FAX: (408) 962-3200
ETV Joint Verification Statement
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 verification centers under ETV, is operated by
Battelle in cooperation with EPA's National Risk Management Research Laboratory. The AMS Center evaluated
the performance of a cavity ring-down spectroscopy (CRDS) unit for the analysis of ammonia in stack gas. This
verification statement provides a summary of the test results for the Picarro Model Gl 103-c ammonia analyzer.
VERIFICATION TEST DESCRIPTION
Testing was performed between July 24 and October 29, 2009 at a full-scale coal fired power plant owned and
operated by the Tennessee Valley Authority. The power plant where testing was performed included multiple 200-
megawatt boilers, each configured with selective non-catalytic reduction (SNCR) NOX reduction capabilities that
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involved the injection of an aqueous urea solution into each boiler. During testing, the Picarro Model Gl 103-c
system was installed in an environmentally controlled instrument shelter and supplied with flue gas that was
sampled from the superheat section of one boiler. The flue gas was drawn from the duct using a dilution probe
(100:1 dilution) incorporating a particulate filter, and was delivered to the CRDS system through approximately
150-200 feet of heated Teflon sampling line. Reference ammonia measurement were performed according to a
modified version of Conditional Test Method-027 (CTM-027), which includes non-isokinetic stack sampling and
ion chromatographic analysis, to allow comparisons to the CRDS measurements. The relative percent difference
(RPD) between the reference measurements and the CRDS measurements was calculated and used to determine
the relative accuracy (RA) of the Model Gl 103-c. After completion of the field testing, the Picarro Model Gl 103-c
was challenged under laboratory conditions by supplying zero air and an ammonia reference standard diluted over
a range of target concentrations to assess precision, linearity, zero/calibration drift, and response time.
QA oversight of verification testing was provided by Battelle and EPA. Battelle technical staff conducted a
performance evaluation audit and Battelle QA staff conducted a technical systems 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 at www.epa.gov/etv/centers/centerl.html.
TECHNOLOGY DESCRIPTION
The following description of the Model Gl 103-c is based on information provided by the vendor. This technology
description was not verified in this test.
The Model Gl 103-c is an analyzer designed to measure ammonia at the parts-per-billion level in the presence of
carbon dioxide, water vapor, and other gas species present in flue gas streams. This analyzer is based on CRDS,
which is a technique in which a gas sample is introduced into a high-finesse optical cavity and the optical
absorbance of the sample is determined, thus providing concentration and/or isotopic ratio measurements of a
particular gas species of interest.
The components which make up a basic CRDS instrument are a laser, a high-finesse optical cavity consisting of
two or more mirrors, and a photo-detector. Operationally, light from a laser is injected into the cavity through one
partially reflecting mirror. The light intensity inside the cavity then builds up over time and is monitored through a
second partially reflecting mirror using a photo-detector located outside the cavity. The "ring-down" measurement
is made by rapidly turning off the laser and measuring the light intensity in the cavity as it decays exponentially
with a time constant, T, that depends on the losses due to the cavity mirrors and the absorption and scattering of the
sample being measured. After shutting off the laser, most of the light remains trapped within the cavity for a
relatively long period of time (i.e., microseconds [fisec]), producing an effective path length of tens of kilometers
through the sample.
The analyzer continuously scans the laser over individual ammonia spectral features and records the absorption
loss and wavelength at each spectral point. Each spectrum is comprised of absorption loss as a function of optical
frequency. The concentration is proportional to the area under each measured spectral feature. Concentration
measurements are provided approximately every second, corresponding to a total of 100 ring-down and
wavelength monitor measurements, which provides sensitivity to approximately 0.3 ppb of ammonia in one
second, or about 0.025 ppb with five of minutes of averaging. The Model Gl 103-c has an operational range of 0-
10 ppm NH3, with an optional extended range up to 50 ppm.
The Model Gl 103-c has dimensions of 43 cm x 25 cm x 59 cm (17" x 9.75" x 23") including the base, and can be
rack mounted or operated on a bench top. The approximate purchase price of the Model Gl 103-c is $55,000.
VERIFICATION OF PERFORMANCE
Table VS-1 provides a summary of selected verification test results for the Picarro Model Gl 103-c.
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Table VS-1. Summary of Verification Results for the Picarro Model G1103-C
Performance
Parameter
Linearity
Accuracy
Precision
Zero/Span Drift
Response Time
Data Completeness
Ease of use
Maintenance
Consumables/waste
generated
Method of
Evaluation
Linear regression of
multipoint calibration
results
Comparison to
reference method
results
Evaluation of daily
zero/span check results
Evaluation of daily
zero/span check results
Calculated from daily
zero/span check results
Ratio of number of
data points collected
to number of potential
data points that could
have been collected
Operator observations
Operator observations
Operator observations
Results
Slope Intercept r
Initial 0.998 (±0.02) 19. 5 (±41.0) 0.997
Final 1.03 (±0.009) -12. 3 (±13. 3) 1.000
Laboratory Testing Field Testing3
Relative Std Dev (RSD) 4.3% -25.2%
Relative Accuracy 4.6% 31.9%
Zero Check Span Check
Mean 1.03 ppb 1590 ppb
St. Dev. 0.77 ppb 5.3 ppb
RSD 11.3% 0.13%
%Diff. from Theory N/A 4.3%
• No apparent trend in changes between zero and span checks
Rise Time Fall Time
Avg. Time 0 sec 30 sec 2 min 0 sec 30 sec 2 min
Mean 02:26 02:40 04:40 00:42 01:07 02:26
Std. Dev. 00:32 00:30 00:20 00:11 00:11 00:32
• Completeness = 100%
• Initial installation was completed in ~45 minutes by vendor
• Subsequent installations were performed by Battelle and on-site support
staff in —45 minutes
• Operation is automated upon powering; requires no external intervention
• Operated unattended for 3 -month duration of the testing period
• Daily space-delimited data files are generated automatically and stored
in separate data files on an internal hard drive
• No routine maintenance activities were performed during testing
• Non-routine maintenance included diagnostic tests performed after
initial installation but prior to routine monitoring periods
• No consumables were used and no waste was generated during routine
monitoring activities
• Compressed gas standards were used for dynamic spiking tests; the
waste gas stream from the dynamic spiking was combined with the
excess flue gas
These results are based on measurements from the entire field sampling system, including the dilution probe, the transfer line from the duct,
and the Model Gl 103-c, compared with reference method measurements taken directly from the duct.
Signed bv Tracv Stenner 10/17/201 1 Signed bv Annette Gatchett 1 1/30/201 1
Tracy Stenner Date Cynthia Sonich-Mullin Date
Manager Director
Environmental Solutions Product Line National Risk Management Research Laboratory
Energy, Environment, and Material Sciences Office of Research and Development
Battelle U.S. Environmental Protection Agency
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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