TDLAS-based photofragmentation spectroscopy for detection of K and KOH in flames under optically thick conditions

Thorin, Emil; Schmidt, Florian M.

doi:10.1364/ol.400614

Cited by 28 publications

(19 citation statements)

References 22 publications

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“…The main K species released to gas-phase during thermochemical biomass conversion are atomic K, potassium hydroxide (KOH) and potassium chloride (KCl) [8,9]. Usually, KOH dominates in combustion, due to the high oxygen availability, while under fuel-rich conditions, the atomic K concentration can be of the same order of magnitude as, or even exceed, the levels of KOH and KCl [10]. An efficient way to improve the understanding of fuel conversion is to perform well-controlled studies of volatile release from biomass particles combusted in laboratory reactors [11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

“…Selective and quantitative in situ detection of all three main K species in hightemperature reacting flows requires relatively complex optical techniques [10,[19][20][21]. However, gaseous atomic K, here referred to as K(g), provides a good indication of K release, especially during the devolatilization phase, and can be detected in a wide dynamic range and with high time-resolution using tunable diode laser-absorption spectroscopy (TDLAS) [10,16,22,23].…”

Section: Introductionmentioning

confidence: 99%

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Potassium Release from Biomass Particles during Combustion—Real-Time In Situ TDLAS Detection and Numerical Simulation

Fatehi

Schmidt

2021

Applied Sciences

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Potassium (K) is one of the main and most hazardous trace species released to the gas-phase during thermochemical conversion of biomass. Accurate experimental data and models of K release are needed to better understand the chemistry involved. Tunable diode laser absorption spectroscopy (TDLAS) is used for simultaneous real-time in situ measurements of gas-phase atomic K, water (H2O) and gas temperature in the vicinity (boundary layer) of biomass particles during combustion in a laboratory single-particle reactor. Atomic K is detected in a wide dynamic range, including optically thick conditions, using direct absorption spectroscopy at the wavelength of 770 nm, while H2O and temperature are determined by calibration-free scanned wavelength modulation spectroscopy at 1398 nm. The high accuracy and repeatability of the setup allows to distinguish measurements with varying initial particle mass, laser beam height above the particle and fuel type. Four types of biomass with different ash composition are investigated: softwood, Salix, Miscanthus and wheat straw. For Salix and wheat straw, the K release behaviour is, for the first time, compared to a detailed numerical particle model taking into account the interaction between K/S/Cl composition in the particle ash. A good agreement is achieved between the measured and calculated time-resolved atomic K concentrations for the devolatilization phase of the biomass particles.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Potassium Release from Biomass Particles during Combustion—Real-Time In Situ TDLAS Detection and Numerical Simulation

Fatehi

Schmidt

2021

Applied Sciences

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“…10 Thorin et al used this method to achieve a large dynamic range of K and KOH absolute concentration measurement in the flame. 11 These indicate that the application of absorption saturation incomplete spectroscopy has great potential in extending spectrum gas sensing to a higher concentration range. The work of Rotondaro et al shown that the concentration of rubidium atoms under optically thick conditions can be determined by the absorption peaks reconstructed from the line-shape wings.…”

Section: Introductionmentioning

confidence: 99%

“…Qu et al proposed a method of fitting absorption saturation spectra with simulated spectra, which realized the measurement of absorption saturation incomplete spectra of potassium atoms under optically thick conditions 10 . Thorin et al used this method to achieve a large dynamic range of K and KOH absolute concentration measurement in the flame 11 . These indicate that the application of absorption saturation incomplete spectroscopy has great potential in extending spectrum gas sensing to a higher concentration range.…”

Section: Introductionmentioning

confidence: 99%

Methods of tunable diode laser absorption saturation spectroscopy to gas sensing under optically thick conditions

Nie

Rao

et al. 2021

Micro & Optical Tech Letters

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The absorption saturation under optically thick conditions will bring difficulties to laser spectroscopy gas sensing. We report the spectrum two wings reconstruction method and the transmitted laser intensity fitting method for tunable diode laser absorption saturation spectroscopy gas absolute measurements under optically thick conditions, and used the modified Lambert Beer's law to calculate methane concentration based on the incomplete spectrum of absorption saturation. The maximum deviation between the experimental measurement results and the standard methane concentration is about 4.7%, which verifies the feasibility of these new methods and also show that they have great potential for expanding the gas sensing range of a single absorption line.

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“…In recent years, tunable diode laser spectroscopy (TDLAS) attracts attention all over the world for gas detections in industrial production and environmental protections [1]- [3]. In the field of gas thermometry, compared with other traditional methods, e.g.…”

Section: Introductionmentioning

confidence: 99%

Ultra-Low Sampled and High Precision TDLAS Thermometry Via Artificial Neural Network

Xie

Tan

et al. 2021

IEEE Photonics J.

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Water vapor temperatures in a heating device were measured by ultra-low sampled and high-precision tunable diode laser spectroscopy (TDLAS). Bichromatic distributed feedback (DFB) lasers were used as light sources. Sampled data at an ultra-low rate was collected after laser passing through a low-pass filter and served as the inputs of an artificial neural network. Classical direct absorption spectroscopy using the line-shape fitting method provided the training dataset, i.e., the integrated absorbances. The proposed method required an ultra-low sampling rate, i.e., only 1/50 of the classical method, but its calculation speed was nearly 14,000 times faster. Also, the proposed method yielded satisfying estimates at temperatures uncovered by the training dataset and was insensitive to random noises.

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TDLAS-based photofragmentation spectroscopy for detection of K and KOH in flames under optically thick conditions

Cited by 28 publications

References 22 publications

Potassium Release from Biomass Particles during Combustion—Real-Time In Situ TDLAS Detection and Numerical Simulation

Potassium Release from Biomass Particles during Combustion—Real-Time In Situ TDLAS Detection and Numerical Simulation

Methods of tunable diode laser absorption saturation spectroscopy to gas sensing under optically thick conditions

Ultra-Low Sampled and High Precision TDLAS Thermometry Via Artificial Neural Network

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