TY - JOUR
T1 - Black liquor devolatilization and swelling - a detailed droplet model and experimental validation
AU - Järvinen, Mika
AU - Zevenhoven, Ron
AU - Vakkilainen, Esa
AU - Forssén, Mikael
N1 - Funding Information:
This work is a part of the Modelling Tools for Combustion Process Development (CODE) program. The Technology Agency of Finland (Tekes), Andritz Corporation, Kvaerner Pulping, the Academy of Finland, and the Walter Ahlström Foundation are gratefully acknowledged for financing this work.
Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2003
Y1 - 2003
N2 - In this paper, we present results from a new detailed physical model for single black liquor droplet pyrolysis and swelling, and validate them against experimental data from a non-oxidizing environment using two different reactor configurations. In the detailed model, we solve for the heat transfer and gas phase mass transfer in the droplet and thereby, the intra-particle gas-char and gas-gas interactions during drying and devolatilization can be studied. In the experimental part, the mass change, the swelling behaviour, and the volume fraction of larger voids, i.e. cenospheres in the droplets were determined in a non-oxidizing environment. The model gave a good correlation with experimental swelling and mass loss data. Calculations suggest that a considerable amount of the char can be consumed before the entire droplet has experienced the devolatilization and drying stages of combustion. Char formed at the droplet surface layer is generally consumed by gasification with H2O flowing outwards from the droplet interior. The extent of char conversion during devolatilization and the rate of devolatilization are greatly affected by swelling and the formation of larger voids in the particle. The more the particle swells and the more homogeneous the particle structure is, the larger is the conversion of char at the end of devolatilization.
AB - In this paper, we present results from a new detailed physical model for single black liquor droplet pyrolysis and swelling, and validate them against experimental data from a non-oxidizing environment using two different reactor configurations. In the detailed model, we solve for the heat transfer and gas phase mass transfer in the droplet and thereby, the intra-particle gas-char and gas-gas interactions during drying and devolatilization can be studied. In the experimental part, the mass change, the swelling behaviour, and the volume fraction of larger voids, i.e. cenospheres in the droplets were determined in a non-oxidizing environment. The model gave a good correlation with experimental swelling and mass loss data. Calculations suggest that a considerable amount of the char can be consumed before the entire droplet has experienced the devolatilization and drying stages of combustion. Char formed at the droplet surface layer is generally consumed by gasification with H2O flowing outwards from the droplet interior. The extent of char conversion during devolatilization and the rate of devolatilization are greatly affected by swelling and the formation of larger voids in the particle. The more the particle swells and the more homogeneous the particle structure is, the larger is the conversion of char at the end of devolatilization.
KW - Black liquor combustion
KW - Char conversion
KW - Numerical modelling
KW - Pyrolysis
UR - http://www.scopus.com/inward/record.url?scp=0242416555&partnerID=8YFLogxK
U2 - 10.1016/S0961-9534(02)00151-4
DO - 10.1016/S0961-9534(02)00151-4
M3 - Article
AN - SCOPUS:0242416555
SN - 0961-9534
VL - 24
SP - 495
EP - 509
JO - Biomass and Bioenergy
JF - Biomass and Bioenergy
IS - 6
ER -