Kinetics of the thermal degradation of rice husks in nitrogen atmosphere

Journal Article · Mon Nov 01 04:00:00 EST 1999 · Energy Sources

OSTI ID:697139

Mansaray, K G; Ghaly, A E ^[1]

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1. Dalhousie Univ., Halifax, Nova Scotia (Canada). Biological Engineering Dept.

The use of agricultural residues for power production has generated increasing interest in the conversion of rice husks to higher quality fuels by thermochemical conversion processes such as pyrolysis, combustion, and gasification. However, the reliable design and operation of thermochemical conversion systems requires considerable knowledge of rice husk thermal degradation characteristics of kinetics. The thrust of this paper therefore was to study the reaction kinetics of four varieties of rice husk at a heating rate of 20 C min{sup {minus}1} in an inert atmosphere of pure nitrogen (99.5% nitrogen, 0.5% oxygen) using thermogravimetric analysis and derivative thermogravimetric techniques. The thermal degradation characteristics and the kinetic parameters (activation energy, preexponential factor, and order of reaction) were determined for the two prominent reaction zones from the thermogravimetric curves. Thermal degradation rates in the first reaction zone were relatively higher than those in the second reaction zone. The initial degradation temperatures were 220, 232, 223, and 240 C for the rice husk varieties Lemont LG, ROK 14, CP 4, and Pa Potho, respectively. Residual weights recorded at 700 C were in the range of 33.9--38.7%. Higher activation energies (29.0--35.4 kJ/mol) and preexponential factors (4.7 {times} 10{sup 3} to 6.4 {times} 10{sup 4} min{sup {minus}1}) were obtained for all rice husk varieties in the first reaction zone as compared to those of the second reaction zone (15.1---17.7 kJ/mol and 1.0 {times} 10{sup 2} to 5.1 {times} 10{sup 2} min{sup {minus}1} for the activation energy and preexponential factor, respectively). The order of reactions was in the range of 0.90--1.08 for the first reaction zone and 0.30--0.36 for the second reaction zone.

• OSTI ID: 697139
• Journal Information: Energy Sources, Journal Name: Energy Sources Journal Issue: 9 Vol. 21; ISSN 0090-8312; ISSN EGYSAO
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
ACTIVATION ENERGY
AGRICULTURAL WASTES
CHEMICAL REACTION KINETICS
PYROLYSIS
RICE
THERMAL DEGRADATION