Simultaneous in situ measurement of CO, H _ 2 O, and gas temperatures in a full-sized coal-fired power plant by near-infrared diode lasers

Abstract

We present what is to our knowledge the first near-infrared diode-laser-based absorption spectrometer that is suitable for simultaneous in situ measurement of carbon monoxide, water vapor, and temperature in the combustion chamber (20-m diameter, 13-m path length) of a 600-MW lignite-fired power plant. A fiber-coupled distributed-feedback diode-laser module at 1.56 microm served for CO detection, and a Fabry-Perot diode laser at 813 nm was used to determine H2O concentrations and temperature from multiline water spectra. Despite severe light losses (transmission, <10(-8)) and strong background radiation we achieved a resolution of 1.9 x 10(-4) (1sigma) fractional absorption, equivalent to 200 parts in 10(6) by volume of CO (at 1450 K, 10(5) Pa) with 30-s averaging time.

Constraining sector-specific CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; emissions in the US

“…For example, a number of studies report on direct GHG measurements from individual facilities. These include direct stack measurements of power plant CO 2 emissions (e.g., Teichert et al, 2003) and numerous recent studies of CH 4 emissions from oil and gas operations: measurements of emissions from pneumatic controllers (Allen et al, 2015), compressor stations , transmission and storage systems , and abandoned wells (Kang et al, 2014). In addition, several site-level studies target agricultural emissions.…”

The AquaVIT-1 intercomparison of atmospheric water vapor measurement techniques

“…The inner section is connected to the middle section via free-space optics and mainly encompasses the open-path White cell, with opto-mechanic components directly attached to the inner walls of the AIDA chamber Giesemann et al, 2003). 2002)) to avoid calibration, while simultaneously permitting an efficient disturbance correction (e.g., for the strong, spectrally broadband optical losses caused by the cloud particles). This technique has been derived from even more demanding measurements in extremely dust-laden combustion chambers (Dreier et al, 2011;Schulz et al, 2007;Awtry, 2006;Teichert et al, 2003;Ebert et al, 1998).…”

“…The resulting absorption profiles are co-added up to 100 times to yield a 1-2 s time resolution. The averaged, in situ raw signal is corrected for spectrally broadband optical losses and electricoptical offsets, converted from time to frequency space, and evaluated via a proprietary Labview-based fitting software taking into account (i) the ideal gas law and an extended Beer-Lambert law (Giesemann, 2003;Schulz et al, 2007;Ebert and Wolfrum, 2001;Teichert et al, 2003;Ebert et al, 2005); (ii) a Voigt line-shape-based spectral model that is fitted to the raw data using a nonlinear Levenberg-Marquardt fitting algorithm, taking into account measured pressure, temperature and absorption path length inside AIDA; (iii) a highly precise characterization of the dynamic laser tuning (using a 10 cm air-spaced precision etalon); and (iv) H 2 O spectral data like our measured air-broadening coefficient (g air = 0.0981 ±0.0002 cm −1 atm −1 at 296 K) and temperature coefficient (n = 0.74 ± 0.01) (Hunsmann et al, 2006) and the tabulated H 2 O line strength from HITRAN 2004/8, which was independently verified within ±3 % uncertainty (Hunsmann et al, 2006) during earlier AIDA measurements. For very low H 2 O concentrations, parasitic absorption effects in the middle section of the spectrometer were also corrected for by using either a secondary detector channel on the cryotransfer optics board or the known ratio between the parasitic and the inner absorption path (0.36 m/82 m).…”

Robust, spatially scanning, open-path TDLAS hygrometer using retro-reflective foils for fast tomographic 2-D water vapor concentration field measurements

“…This version of direct TDLAS has been presented for numerous applications, e.g., biological (Hunsmann et al, 2008;Wunderle et al, 2009), engineering (Ortwein et al, 2010Wagner et al, 2009;Teichert et al, 2003), or atmospheric research (Buchholz et al, 2013).…”

“…These setups allow for very fast measurements, since all channels can be recorded simultaneously and the field measurement rate equals the rate at which the concentrations along each projection are measured. However, such highly parallel, bi-static setups either require large amounts of light-source-detectorpairs and the appertaining data acquisition channels (Wright et al, 2005;Terzija et al, 2008;Terzija and McCann, 2011;Ma et al, 2013) or are somewhat limited regarding spatial resolution (Ma et al, 2009;Deguchi, 2012). Additionally, a disadvantage of bi-static setups in field applications is the cumbersome alignment of many detectors.…”