Kinetic Modeling of Coal/Agricultural By-Product Blends

Abstract

There is renewed interest worldwide in the production of sustainable energy from renewable sources, such as biomass, aimed mainly at the decrease of fossil fuels use. Except for its potential to be CO2 “neutral” during combustion, biomass has a low sulfur content and a high volatile concentration: these characteristics favor clean combustion conditions. The knowledge of the kinetics of biomass pyrolysis and combustion is important for the control of such thermochemical processes. The main objective of this work was to determine the kinetic parameters of thermal decomposition of two biomass materials, olive kernel and straw, and of their mixtures with a high- and a low-rank coal. The study was carried out using a thermogravimetric analyzer (TGA) in nitrogen atmosphere, at a heating rate of 10 °C/min. A kinetic model, involving first-order independent parallel reactions, was used. Activation energies and frequency factors were determined for two different particle sizes. The analysis indicated that the pyrolysis of the coals and the biomass samples could be modeled successfully via the independent reactions models, the pyrolysis of biomass being described by reactions corresponding to hemicellulose, cellulose, and lignin decomposition. The results showed that the chemical composition of each biomass type plays a fundamental role in the kinetics determination. Smaller conversion times and increased devolatilization rates were obtained, when biomass was added in the fuel blend with coal. The additive properties of coal and biomass, pyrolyzed in blends, were examined. It was proven that the mass loss vs time during thermal conversion of coal/biomass blends is well-described by the sum of each individual coal and biomass decomposition.

Kinetic models comparison for non-isothermal steam gasification of coal–biomass blend chars

“…Several authors have observed interactions between the components of coal and biomass blends [10,37], while others have reported additive behaviour [38][39][40][41][42][43]. Table 3 shows the kinetic parameters (E, k 0 and ψ) determined from the data obtained at the three heating rates (5, 10 and 15 K min -1 ) for all the char samples together with the coefficients of determination, R 2 , for each model and char sample.…”

Thermogravimetric and Reaction Kinetic Analysis of Biomass Samples from an Energy Plantation

“…10,[12][13][14][15][16][17][18][19][20][21][22] For the description of the present data set of three samples at four heating programs, six partial peaks were necessary. Their parameters and characteristics are listed in Table 7.…”

“…A wide range of activation energies has been reported in the literature of biomass materials. 10,[12][13][14][15][16][17][18][19][20][21][22][23]40 The Details on the Handling of Parameters m() and T. As described above, the magnitude of the m() and T parameters were constrained into physically meaningful ranges by choosing appropriate  values in eq 8.…”

“…Usually the mass loss or mass loss rate is described by models assuming biomass as sum of its constituents or sum of pseudocomponents. 10,[12][13][14][15][16][17][18][19][20][21][22][23] In the present paper, we study the thermal behavior of young shoots obtained from a short-rotation experimental energy plantation in Hungary. The cultivation of fast growing species is considered as a viable source for energy.…”

Thermogravimetric Study of Biomass Pyrolysis Kinetics. A Distributed Activation Energy Model with Prediction Tests

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] The biomass fuels and raw materials contain a wide variety of pyrolyzing species. Even the same chemical species may have different reactivity if their pyrolysis is influenced by other species in their vicinity.…”