Известия Томского политехнического университета: Инжиниринг георесурсов (Dec 2020)

KINETIC CHARACTERISTICS OF BIOMASS PYROLYSIS

  • Roman B. Tabakaev,
  • Dariga B. Altynbaeva,
  • Kanipa T. Ibraeva,
  • Alexander S. Zavorin

DOI
https://doi.org/10.18799/24131830/2020/12/2945
Journal volume & issue
Vol. 331, no. 12
pp. 117 – 130

Abstract

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The relevance of the study is caused by the tendency to increase the share of renewable energy in the fuel and energy balance to reduce the harmful effects on the environment. The main aim is to determine the kinetic parameters of biomass pyrolysis by G. Friedman's method based on the results of differential thermal analysis. Objects: straw, grain processing waste (wheat bran), cedar nutshell, pine sawdust, lowland peat of the Sukhovskoe field, as well as livestock waste from cattle. Methods. Thermotechnicalcharacteristics of biomass samples are determined according to certified methods (GOST 11305-2013, GOST 11306-2013, GOST R 54186-2010, GOST R 56881-2016, GOST 32990-2014); values ​​of the calorific value were determined using the ABK-1 calorimeter (RET, Russia) in accordance with GOST 147-2013 (ISO 1928-2009); elemental analysis of its organic part was carried out on a Vario Micro Cube (Elementar, Germany) device; the kinetic characteristics of low-temperature pyrolysis of biomass were determined by G. Friedman's method based on differential thermal analysis carried out at a temperature of 313–1273 K at a heating rate of 5, 15 and 30 K/min. Results. Thermal decomposition of biomass in the range of 313–1273 K occurs in two stages: the first stage proceeds in the temperature range from 463–488 to 623–653 K and is characterized by a sharp decrease in the mass of samples from 24 (peat) to 63% (sawdust); the second stage is observed from 623–653 to 873 K with a significantly smaller change in the mass of the samples (from 9 to 14%).With a further increase in temperature, the organic part of the samples practically did not undergo transformation, changes occurred only in the mineral part of peat at a temperature of 923–1123 K and were associated with the decomposition of calcium carbonate.The dependences of activation energy (Ea) on the degree of biomass conversion (w/w0) were determined, according to which its average values were calculated: for straw – 21,4 kJ mol–1; for sawdust – 20,7 kJ mol–1; for shell – 24,2 kJ mol–1; for livestock waste from cattle – 23,1 kJ mol–1; for bran – 33,1 kJ mol–1; for peat – 24,0 kJ mol–1.The values of the pre-exponential factor (A) for the studied biomass species are in the range 82,42–2377,01 h–1.

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