Assessment of the release of atomic Na from a burning black liquor droplet using quantitative PLIF

Abstract

The quantitative measurement of atomic sodium (Na) release, at high concentration, from a burning black liquor droplet has been demonstrated using a planar laserinduced fluorescence (PLIF) technique, corrected for fluorescence trapping. The local temperature of the particle was measured to be approximately 1700˚C, at a height of 10 mm above a flat flame burner. The PLIF technique was used to assess the temporal release of atomic Na from the combustion of black liquor and compare it with the Na concentration in the remaining smelt. A first-order model was made to provide insight using a simple plug-flow reactor model based on the independently measured concentration of residual Na in the smelt as a function of time. This model also required the dilution ratio of the combustion products in the flat flame entrained into the plume gas from the black liquor particle to be estimated. The key findings of these studies are: (i) the peak concentration of atomic Na from the combustion of the black liquor droplets is around 1.4 ppm; (ii) very little atomic Na is present during the drying, devolatilisation or char combustion stages; and (iii) the presence of atomic Na during smelt phase dominates over that from the other combustion stages.

Sodium and Potassium Released from Burning Particles of Brown Coal and Pine Wood in a Laminar Premixed Methane Flame Using Quantitative Laser-Induced Breakdown Spectroscopy

“…3b), but not in the other stages, and the elliptically shaped plasma generated by the LIBS is evident in all stages. The visually distinct features of each stage of combustion were used to identify them following earlier work, 7,8 to confirm direct measurements and to estimate the duration of each phase, namely devolatilization (s d ), char (s c ), and ash cooking (s a ) phases.…”

“…Van Eyk et al 7 developed a quantitative planar laser-induced fluorescence (PLIF) technique providing time-resolved measurements and planar distribution of atomic Na released from a single burning coal particle during the char phase. Saw et al 8 then applied the same technique to measure atomic Na released during black liquor combustion. However, the significant scattering from soot that occurs during the devolatilization stage leads to low signal-to-noise ratio of the PLIF measurement during that stage of combustion.…”

“…For example, scattering was found to be absent from the similar calibration process employed in the PLIF technique reported by van Eyk 7 and Saw. 8 Hence, the LIBS method is applied only to gaseous species, indicating that both the matrix and size effects can be neglected. Furthermore, Diwakar 24 et al also concluded that the size effect can be diminished by applying a sufficient delay time of approximately 30 to 60 ls.…”

Measurement of atomic sodium release during pyrolysis and combustion of sodium-enriched Zhundong coal pellet

“…where A and k (mm -1 ) are constants and [Na] p is the concentration of atomic sodium around the pellet surface. If the decay of the atomic sodium concentration is governed by diffusion, there is a simplified diffusion model [32][33][34] can be used to model the decay, which assumes the combustion in proximity to the coal sample can be regarded as a round jet flame and the flat flame is a co-flow. In this case,…”

On-line spectroscopic and spectrometric methods for the determination of metal species in industrial processes☆

“…Another study used planar LIF [293] to measure the temporal release of atomic Na release from a burning black liquor droplet above a flat flame burner. Here, the planar LIF images obtained were averaged to obtain concentration data at particular positions in the flame.…”