As environmental regulations become more stringent and as more gaseous pollutants need to be monitored, there is a need for a cost-effective measurement technique to evaluate emissions from electric generating units and other processing facilities. A Fourier Transform Infrared (FTIR) analyzer is a solution for this issue. FTIR analysis is a technology that generates real-time emissions data at high sensitivities. FTIR analyzers can measure nearly all gaseous compounds while requiring little to no calibration. The two biggest advantages that FTIR analysis has over traditional measurement methodologies are its ability to measure many different gaseous species simultaneously and its ability to generate immediate results.

1. Testing Applications for FTIR Analyzers
As environmental regulations become more stringent and as more gaseous pollutants need to be monitored,
there is a need for a cost-effective measurement technique to evaluate emissions from electric generating
units and other processing facilities. A Fourier Transform Infrared (FTIR) analyzer is a solution for this
issue. FTIR analysis is a technology that generates real-time emissions data at high sensitivities (ppm to
ppb levels). FTIR analyzers can measure nearly all gaseous compounds (non-elemental) while requiring
little to no calibration. Due to FTIR analysis being performed at temperatures above the boiling point of
water, water soluble compounds (i.e. acid gases, ammonia, etc.) that are difficult to measure by traditional
methods are easily quantified by FTIR measurement. FTIR analyzers can be used to measure Volatile
Organic Compounds (VOCs) and Total Hydrocarbons (THCs) by adding up the composition of all pertinent
hydrocarbons. VOC and THC measurements can be tailored to each specific site to reduce the measurement
error.
The two biggest advantages that FTIR analysis has over traditional measurement methodologies are its
ability to measure many different gaseous species simultaneously and its ability to generate immediate
results. FTIR analyzers collect spectral data from the sample gas and generate composition values based on
the spectral data. As the FTIR analyzer generates the entire IR spectrum of the sample gas, multiple species
can be analyzed simultaneously. Also, the spectrum from each test can be saved and reanalyzed to obtain
additional data if desired. These results are generated on-site in real-time, therefore results can be obtained
instantaneously. Traditional methods for many gaseous species require collected samples to be shipped out
to an analytical lab before generating results. Due to the decreased turnaround time, FTIR measurement is
beneficial when while tuning or making process changes.
As explained above, FTIR analysis is a useful tool for gas composition measurement that can be applied to
a variety of processes and activities. Some applications of the FTIR technology include:
• Environmental compliance testing
• Air Quality Control System testing/studies
o Emissions/process optimization
o Tuning and balancing emission profiles
o Dry sorbent/activated carbon injection studies
• Stack/CEMS monitoring
• VOC and THC emissions measurement
o Coal-fired to natural gas-fired conversions
o Cement kiln/waste incineration emissions measurements
• SCR tuning
o Instantaneous measurement of NH3 slip and SO3
• Formaldehyde emissions from gas turbines
o Formaldehyde accounts for 2/3 of HAP emissions from gas turbines
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2. Case Histories:
SCR Tuning:
ICT provided testing support to a large-scale utility boiler that required SCR tuning and performance testing
before and after replacement of the catalyst. While the manual method CTM-027 was required for the
performance testing, ICT utilized the FTIR analyzer to provide real-time ammonia slip measurements
during tuning. Real-time measurements of ammonia slip helped expedite the tuning process by quickly
revealing the effect of changes made to ammonia injection and validated that the SCR was operating more
efficiently with reduced ammonia slip following the tuning process.
VOC Testing:
ICT provided testing support to a large-scale utility boiler that was converting from firing pulverized coal
to natural gas. ICT performed flue gas sampling at the economizer outlet to validate CO catalyst
performance and to verify that volatile organic compound (VOC) emissions were below allowable limits.
The customer requested that ICT use EPA Method 25A to measure VOC emissions and to report VOC
concentrations without the contribution of methane and ethane. Method 25A requires the use of a flame
ionization detection (FID) analyzer, however most FID analyzers cannot evaluate both methane and ethane
contributions to the VOC measurement. In order to meet the testing requirements given by the customer,
ICT utilized a FID analyzer to measure the total hydrocarbons (THC) in the sample stream and used the
FTIR to measure the methane and ethane contributions. The methane and ethane concentrations measured
by the FTIR were then subtracted from the THC concentration measured by the FID analyzer to give VOC
concentration that met the customer’s criteria.
In addition to measuring methane and ethane, the FTIR analyzer software has built-in correlations for
measuring THC. This correlation was observed during the testing to evaluate its accuracy when compared
to the FID analyzer. The average THC concentrations measured by the FTIR varied by no more than 1.5
ppm from the average FID analyzer response. For future projects, ICT may consider using the FTIR
analyzer by itself to measure VOCs.