Experimental exploration of potassium compounds in the vicinity of a burning biomass pellet : From near-surface to downstream
(2024) In Proceedings of the Combustion Institute 40(1-4).- Abstract
The concentrations of gas-phase potassium hydroxide (KOH), potassium chloride (KCl) and atomic potassium (K(g)) were quantitatively measured from the near-surface to downstream area of burning pinewood pellets by a newly developed photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS) technique to reveal the original form of the released potassium. The novel arrangement of the PF-TDLAS system enabled a spatial resolution of ∼1 mm3, which made it possible to obtain temporal release profiles of K(g)/KOH/KCl at different heights above the burning pellet surface. Surface temperature and mass loss of the wood pellet as well as the gas temperature at measurement points were measured simultaneously. During the... (More)
The concentrations of gas-phase potassium hydroxide (KOH), potassium chloride (KCl) and atomic potassium (K(g)) were quantitatively measured from the near-surface to downstream area of burning pinewood pellets by a newly developed photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS) technique to reveal the original form of the released potassium. The novel arrangement of the PF-TDLAS system enabled a spatial resolution of ∼1 mm3, which made it possible to obtain temporal release profiles of K(g)/KOH/KCl at different heights above the burning pellet surface. Surface temperature and mass loss of the wood pellet as well as the gas temperature at measurement points were measured simultaneously. During the devolatilization stage, the release of all three potassium species was observed, with each of them accounting for ∼1/3; while in char oxidation stage, the release of KOH was dominant, but the release intensity was strongly influenced by the local oxygen content. The results from different measurement heights showed there was a notable difference in potassium release profiles of different potassium species over the near-surface area, where the detected potassium forms were the best representative of the originally released forms of potassium. For a period of time during the devolatilization stage, only K(g) was detected in the near-surface area, and the concentration was significantly lower than the downstream area where KOH and KCl coexisted. This suggested that a large amount of potassium might leave the pellet as organic-K, which cannot be detected by the PF-TDLAS method. During char oxidation stage, the total potassium concentration at the near-surface area was also lower than the downstream area, but it was due to the lack of oxygen at the measurement position. A potassium release mechanism during the devolatilization stage of biomass combustion was proposed based on the experimental measurements, and the results also indicated the importance of spatially resolved measurement.
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- author
- Liu, Siyu LU ; Weng, Wubin LU ; He, Yong ; Aldén, Marcus LU ; Wang, Zhihua and Li, Zhongshan LU
- organization
- publishing date
- 2024-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Biomass, Near-surface area, Photofragmentation tunable diode laser absorption spectroscopy, Potassium compounds, Release characteristics
- in
- Proceedings of the Combustion Institute
- volume
- 40
- issue
- 1-4
- article number
- 105583
- publisher
- Elsevier
- external identifiers
-
- scopus:85198722679
- ISSN
- 1540-7489
- DOI
- 10.1016/j.proci.2024.105583
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2024 The Combustion Institute
- id
- 59b5e75d-9e1e-4908-b078-be4e4dbc3227
- date added to LUP
- 2024-07-29 08:32:19
- date last changed
- 2024-08-12 15:44:08
@article{59b5e75d-9e1e-4908-b078-be4e4dbc3227,
abstract = {{<p>The concentrations of gas-phase potassium hydroxide (KOH), potassium chloride (KCl) and atomic potassium (K(g)) were quantitatively measured from the near-surface to downstream area of burning pinewood pellets by a newly developed photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS) technique to reveal the original form of the released potassium. The novel arrangement of the PF-TDLAS system enabled a spatial resolution of ∼1 mm<sup>3</sup>, which made it possible to obtain temporal release profiles of K(g)/KOH/KCl at different heights above the burning pellet surface. Surface temperature and mass loss of the wood pellet as well as the gas temperature at measurement points were measured simultaneously. During the devolatilization stage, the release of all three potassium species was observed, with each of them accounting for ∼1/3; while in char oxidation stage, the release of KOH was dominant, but the release intensity was strongly influenced by the local oxygen content. The results from different measurement heights showed there was a notable difference in potassium release profiles of different potassium species over the near-surface area, where the detected potassium forms were the best representative of the originally released forms of potassium. For a period of time during the devolatilization stage, only K(g) was detected in the near-surface area, and the concentration was significantly lower than the downstream area where KOH and KCl coexisted. This suggested that a large amount of potassium might leave the pellet as organic-K, which cannot be detected by the PF-TDLAS method. During char oxidation stage, the total potassium concentration at the near-surface area was also lower than the downstream area, but it was due to the lack of oxygen at the measurement position. A potassium release mechanism during the devolatilization stage of biomass combustion was proposed based on the experimental measurements, and the results also indicated the importance of spatially resolved measurement.</p>}},
author = {{Liu, Siyu and Weng, Wubin and He, Yong and Aldén, Marcus and Wang, Zhihua and Li, Zhongshan}},
issn = {{1540-7489}},
keywords = {{Biomass; Near-surface area; Photofragmentation tunable diode laser absorption spectroscopy; Potassium compounds; Release characteristics}},
language = {{eng}},
number = {{1-4}},
publisher = {{Elsevier}},
series = {{Proceedings of the Combustion Institute}},
title = {{Experimental exploration of potassium compounds in the vicinity of a burning biomass pellet : From near-surface to downstream}},
url = {{http://dx.doi.org/10.1016/j.proci.2024.105583}},
doi = {{10.1016/j.proci.2024.105583}},
volume = {{40}},
year = {{2024}},
}