Non-isothermal thermal analysis of different originated lignocellulosic biomass, non-treated and torrefied by microwave treatment
2021
Arshanitsa, A., EkoKompozit, Ltd., Salaspils, Salaspils Municipality (Latvia);Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Andersone, A., EkoKompozit, Ltd., Salaspils, Salaspils Municipality (Latvia);Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Telysheva, G., EkoKompozit, Ltd., Salaspils, Salaspils Municipality (Latvia);Latvian State Inst. of Wood Chemistry, Riga (Latvia)
The effect of microwave (mw) assisted torrefaction on the combustion performance of three lignocellulosic feedstocks, namely, softwood, wheat straw and peat was studied by means of non-isothermal thermal analysis realized in air atmosphere. Each feedstock was torrefied at 200 ºC, 250 ºC and 300 ºC using a laboratory scale microwave torrefactor of original construction. The differential thermal gravimetric curves of all non-treated and torrefied samples are separated into two main stages responsible for oxidative volatilization and char combustion. The degradation of wheat straw derived fuel was more complicated. Two separated peaks were observed in char combustion profiles for this feedstock, both non-treated and torrefied. The apparent activation energy of conversion for each degradation stage and its average value for processing were calculated by integration of the Arrhenius equation using Coats-Redfern methods. The averaged activation energy of the conversion of torrefied samples exceeded that of non-treated samples for all feedstocks under study and varied in the range of 132–211 kJ•mol-1 vs 75–152 kJ•molE–1 for non-treated biomass. The calculated activation energy of non-treated and torrefied samples increased in the rank: peat – softwood – wheat straw. Although non-torrefied biomass decomposed at lower energy input, the total heat output as a result of thermal oxidation of torrefied feedstocks increased up to 62–83% vs that of non-treated biomass.
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