In Situ Measurement of Potassium Release during Biomass Combustion Using Laser-Induced Breakdown Spectroscopy: Effect of Silicate on Potassium Release

• Published in: Energy & fuels Vol. 34; no. 3; pp. 3262 - 3271
• Main Authors: Zhao, Haibo, Wakil, M.A, Viljanen, Jan, Song, Qiang, Yao, Qiang, Kwong, C. W, Alwahabi, Zeyad T
• Format: Journal Article
• Language: English
• Published: American Chemical Society 19.03.2020
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/acs.energyfuels.9b03966

In this study, an improved calibration method for the in situ measurement of potassium (K) concentration in the flame field was developed using laser-induced breakdown spectroscopy. The temporal behaviors of K release and particle temperature were recorded simultaneously during biomass combustion. During combustion of raw willow wood, the majority of K was released during the ash-cooking stage, followed by char combustion stage, and only a small amount of K was released during the initial devolatilization stage. The results indicated that during the devolatilization stage, K was released because of the decomposition of organic K. Char-K was subsequently converted to K2CO3, and most K2CO3 was subsequently released during the final ash-cooking stage. In the case of rice straw combustion, K was mainly released during the initial devolatilization stage, most likely as KCl. The transformation of char-K and the K–Si reaction forming K–silicates mainly occurred during the char combustion stage; K was found to be released slowly from K–silicates during the ash-cooking stage. The combustion of willow wood with different Si contents demonstrated that Si significantly inhibited the K release during both char combustion and the ash-cooking stage.