Activated combustion of biomass blends by microwave pre-treatment of straw

Goldšteins, Linards; Valdmanis, Raimonds; Zake, Maija

doi:10.22616/erdev.2021.20.tf028

Cited by 1 publication

(5 citation statements)

References 6 publications

(17 reference statements)

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“…The deviation from linear approximation, assuming the additivity of the weight loss rates of selectively activated blend components, confirms that the MW pre-treatment of pellets activates the synergetic interactions between the pre-treated and raw biomass pellets. This supports the enhanced yield and burnout of volatiles, thus improving the composition of emissions, decreasing the mass fraction of polluting NO emissions, and increasing the overall combustion efficiency and heat output [30,31].…”

Section: Introductionsupporting

confidence: 59%

“…To estimate the effect of MW pre-treatment of wood and wheat straw pellets on the thermo-chemical conversion of their blends with raw peat pellets, the MW-induced variations of the main characteristics of the blend components and pellets' structure were preliminary estimated and considered [30,31]. Wood, wheat straw, and peat have different elemental, chemical compositions, surface area, porosity, and contents of volatile matter in raw biomass.…”

Section: Thermal Decomposition Of Selectively Activated Biomass Blendsmentioning

confidence: 99%

“…Increasing the surface area, porosity, and reactivity of pellets and the concentration of the active sites [33] enhances the thermo-chemical conversion of pre-treated pellets [30] which depends on the MW pre-treatment temperature. Increasing the temperature of MW pre-treatment above 470 K correlated with the carbonization of pre-treated pellets, thus increasing the carbon content in the pre-treated pellets, while decreasing the hydrogen and oxygen content.…”

Section: Thermal Decomposition Of Selectively Activated Biomass Blendsmentioning

confidence: 99%

“…For straw pellets, the HHV during MW pre-treatment increased from 18.4 MJ/kg for raw pellets to 18.7 MJ/kg at T = 473 K and to 20.8 MJ/kg at T = 548 K. Besides, the data of the TG/DTG analysis allowed us to conclude that the enhanced yield of volatiles during MW pre-treatment of pellets and their carbonization results in a decrease of the relative heat output at the combustion stage of volatiles, whereas the heat output increases at the char conversion stage for pre-treated pellets [34]. The highest decrease of the heat output during the combustion of volatiles, if compared to that of char conversion, was observed for the pre-treated wheat straw pellets which had the highest weight loss of volatiles during MW pre-treatment of pellets along with the highest increase in reactivity of the pre-treated pellets [29,30].…”

Section: Thermal Decomposition Of Selectively Activated Biomass Blendsmentioning

confidence: 99%

“…This suggests that the thermal behaviour of biomass blends can be controlled by providing selective MW pre-treatment of the blend components, which results in partial thermal destruction of the main constituents of lignocellulosic biomass [28], promoting changes in their structure, in chemical and elemental composition responsible for the variations of the rate of thermal decomposition, of the yield of volatiles, and formation of char [29]. Moreover, an increase of the heating values, specific surface area, and reactivity of MW pre-treated biomass particles [14,15] affects the kinetics of the thermo-chemical conversion of selectively activated biomass blends which are composed of MW pre-treated and raw biomass pellets of different origin [30]. The deviation from linear approximation, assuming the additivity of the weight loss rates of selectively activated blend components, confirms that the MW pre-treatment of pellets activates the synergetic interactions between the pre-treated and raw biomass pellets.…”

Section: Introductionmentioning

confidence: 99%

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Thermo-Chemical Conversion of Microwave Selectively Pre-Treated Biomass Blends

et al. 2022

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Possibilities of more efficient use of regional lignocellulosic resources (wood, wheat straw, peat) of different origin for an environmentally friendly energy production using selectively MW pre-treated blends of commercial wood or wheat straw pellets with raw peat pellets are studied. A hypothesis is proposed and tested that selective MW pre-treatment of wood or wheat straw pellets at the frequency 2.45 GHz and blending of MW pre-treated pellets with raw peat pellets can be used to enhance and control the thermo-chemical conversion of biomass blends. To test this hypothesis, a combined experimental study and mathematical modelling of the processes were performed. The thermo-chemical conversion of selectively activated blends was experimentally studied using a batch-size pilot device, which consists of a biomass gasifier and a combustor. To evaluate the effect of selective MW pre-treatment of biomass pellets on the thermo-chemical conversion of pre-treated blends, measurements of the kinetics of weight loss, yield of combustible volatiles, flame temperature, heat output of the device, and composition of emissions were made at different MW pre-treatment regimes of wheat straw and wood pellets and different mass fractions of pre-treated pellets in biomass blends. The developed novel 2D numerical model of thermo-chemical conversion of MW pre-treated straw confirmed that the pre-treatment of wheat straw pellets increases the generated heat and significantly affects the temperature distribution in the flame/bed zones. It was confirmed that MW pre-treatment leads to a faster thermal decomposition of biomass pellets, synergistically activating the non-treated parts of blends. The overall improved yield of combustible volatiles and their complete combustion provide a surplus of heat production by limiting the formation of GHG emissions, which allows promoting MW pre-treated biomass of different origin as efficient regional bioenergy resources for energy production.

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Section: Introductionsupporting

confidence: 59%

Section: Thermal Decomposition Of Selectively Activated Biomass Blendsmentioning

confidence: 99%

Section: Thermal Decomposition Of Selectively Activated Biomass Blendsmentioning

confidence: 99%

Section: Thermal Decomposition Of Selectively Activated Biomass Blendsmentioning

confidence: 99%