Combustion kinetics of biomass materials in the kinetic regime

G. Várhegyi, Zoltán Sebestyén, Z. Czégény, Ferenc Lezsovits, Sándor Könczöl

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Wheat straw, willow from an energy plantation, and municipal sewage sludge were studied by thermogravimetry at linear and nonlinear heating programs in gas flows containing 4 and 20% oxygen. A kinetic scheme of successive devolatilization and char burnoff reactions was assumed. A distributed activation energy model (DAEM) was assumed for the devolatilization with a Gaussian distribution and a constant pre-exponential factor. The burnoff of the forming char was approximated by first-order kinetics with respect to the amount of char. The dependence of the reactions upon the oxygen concentration was described by power functions. This model gave a suitable description for the wheat straw and sewage sludge. An additional partial reaction with accelerating kinetics was needed for describing the oxidative cellulose pyrolysis in the willow sample. The evaluations were carried out by the method of least squares. 9-17 model parameters were determined from ten experiments for each sample. Good fit quality and reasonable kinetic parameters were obtained. Test evaluations revealed that the first-order kinetics with respect to the amount of char is an adequate model; the assumptions of more complex char burnoff submodels did not led to notable improvements. The replacement of the DAEM devolatilization by simpler n-order kinetics gave inadequate performance. Earlier works with simpler models and linear temperature programs showed that the successive mechanism can be well-approximated by parallel reactions. Such approximations proved to be viable in the present case, too.

Original languageEnglish
Pages (from-to)1323-1335
Number of pages13
JournalEnergy and Fuels
Volume26
Issue number2
DOIs
Publication statusPublished - Feb 16 2012

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Biomass
Kinetics
Salix
Straw
Sewage sludge
Activation energy
Oxygen
Gaussian distribution
Kinetic parameters
Cellulose
Flow of gases
Thermogravimetric analysis
Pyrolysis
Heating
Experiments
Temperature

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Energy Engineering and Power Technology
  • Fuel Technology

Cite this

Combustion kinetics of biomass materials in the kinetic regime. / Várhegyi, G.; Sebestyén, Zoltán; Czégény, Z.; Lezsovits, Ferenc; Könczöl, Sándor.

In: Energy and Fuels, Vol. 26, No. 2, 16.02.2012, p. 1323-1335.

Research output: Contribution to journalArticle

Várhegyi, G. ; Sebestyén, Zoltán ; Czégény, Z. ; Lezsovits, Ferenc ; Könczöl, Sándor. / Combustion kinetics of biomass materials in the kinetic regime. In: Energy and Fuels. 2012 ; Vol. 26, No. 2. pp. 1323-1335.
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