Effects of operational parameters on torrefaction performance of coffee husk and cotton stalk mixed biomass: a surface response methodology approach

Yeayneabeba, Tadesse; Kassahun, Shimelis Kebede; Kiflie, Zebene

doi:10.1007/s13399-021-01649-w

Cited by 7 publications

(6 citation statements)

References 37 publications

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“…The E a and A values of SS samples, and BH samples were higher in zone II than III; for example, the E a for SS as raw was 218.269 kJ/mol for zone II but was 199.021 kJ/mol for zone III, and it agrees with the work of other researchers [43][44][45][46]. At temperatures below 300 °C, the inert cellulose is first transformed into active cellulose before being thermally broken down into tar, gas, and char.…”

Section: Kinetics Parameterssupporting

confidence: 90%

“…In addition, the color of moderately torrefied biomass might result from the synthesis of phenols and aldehydes under moderate torrefaction conditions (250 °C). This conclusion aligns with research results on improving rice husk's fuel characteristics [48] and coffee husk and cotton stalk mixed biomass [46]. approved by the standard less10% [36].…”

Section: The Physical Appearance Of Torrefaction Productssupporting

confidence: 89%

“…The values obtained for activation energy, as well as a pre-exponential component using the Coats and Redfern procedure, are higher than the values obtained using the direct Arrhenius method, as shown in Fig. 11, which agrees with the results found in the literature [46,47]. The main pyrolysis zones were zones II and III according to the starting and ending of the peaks that appear in DTG curves for all samples [47,48].…”

Section: Kinetics Parameterssupporting

confidence: 88%

“…2, the consistent color of all samples proves that the torrefaction procedure is applied uniformly to the whole sample. There are several possible explanations for this shift in color, including variations in the lignocellulosic content that causes chemical changes and surface changes in the biomass and changes in light absorption, reflection, and diffraction [46]. The color of the samples often changes as the torrefaction temperature increases, indicating that they have undergone a significant amount of conversion.…”

Section: The Physical Appearance Of Torrefaction Productsmentioning

confidence: 99%

“…This also indicates that oxygen is far more affected by torrefaction than carbon. Biomass undergoes dehydration, dehydroxylation, and decarboxylation of its constituents, most notably hemicellulose [46,47]. Therefore, the biomass loses a significant amount of its oxygen content throughout the torrefaction process [56].…”

Section: Characterization Of Torrefied Productmentioning

confidence: 99%

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The influence of torrefaction on the biochar characteristics produced from sesame stalks and bean husk

Khairy

Amer

Ibrahim

et al. 2023

Biomass Conv. Bioref.

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Torrefaction encourages homogeneity and enhances the energy-producing capabilities of biomass. In the current study, bean husk (BH) and sesame stalks (SS) were torrefied for 30 and 60 min at operating temperatures of 200, 225, 250 and 275, and 300 °C with nitrogen purging. Mass yield (MY), higher heating value (HHV), energy yields (EY), and torrefaction severity index (TSI) were examined. The variations of the biochar characteristics, pyrolysis kinetics by applying two models (Coats and Redfern (CR) and Direct Arrhenius (DA)), and crystallinity index (CRI) were depicted. Depending on pyrolysis kinetics, thermodynamic activation parameters were derived to elucidate biomass pyrolysis. The alterations in the torrefied materials’ composition were also analyzed using Fourier transform infrared spectroscopy (FTIR). The calculations revealed that the torrefied SS and BH decreased MY by 32.74, 29.02% and decreased EY 26, 20.97%, increased high heating values by 14.1, 13.52%, increased fixed carbon by 55.1, 39.91% respectively, and had a slight reduction in bulk density (approximately 2%). Generally, 275 °C and 30 min were the optimal conditions for a balanced torrefaction of SS and BH based on the HHV that reached to 20.5, 16.2 MJ/kg and EY that reached to 86.16 and 85.56% respectively. The FTIR, XRD, and the thermogravimetric results showed that the torrefaction treatment altered samples owing to carbohydrate breakdown, a rise in lignin, and a reduction in hemicellulose as the temperature of the torrefaction process increased. The CR methodology yielded greater frequency factor (A) and activation energy (Ea) values than the DA method. The broadest peak width, lowest average Ea, and lnA were seen in sesame stalks that had been torrefied at 300 °C and 30 min that reached to 107.85 (kJ/mol) and 13.57 (min−1). Results indicated an excellent linear relationship with the index of comprehensive pyrolysis (CPI), CRI, atomic H/C ratio, severity index, and EY.

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Section: Kinetics Parameterssupporting

confidence: 90%