Release of potassium in association with structural evolution during biomass combustion

Native Scottish wood samples were investigated as potential, locally sourced, raw materials for biochar production. Screening experiments identified pure softwood as the preferable feedstock. Influence of operational parameters, i.e. activating gas flow rate (CO2), heating ramp rate and contact time on final biochar characteristics, was investigated using design of experiments. Surface area and biochar yield were selected as response variables. Minitab was used to define experimental run conditions and suggested an optimal output at 60 min contact time and 15 °C/min ramp rate for maximum responses. The highest surface area (764 m2/g) was achieved at 850 °C from softwood, albeit with a low yield of 15%. Under optimised conditions, the observed surface area was 613 m2/g with ~ 18% yield. Pareto charts suggested no influence of gas flow rate on chosen responses, which correlated well with experimental data. Pore structure was a combination of micro- and mesopores with average pore widths of 3–5 nm and an average point of zero charge of 7.40 ± 0.02. Proximate analysis showed an increase in fixed carbon content from 20%, in the feedstock, to 80%, in the optimised biochar. Morphological analysis showed a layered carbon structure in the biochars. The results show the significance of the selected feedstock as a potential source of biochar material and the relevance of interplay of operational variables in biochar development and their final characteristics.

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“…Fig.1Schematic diagram of muffle furnace equipped with a weighing system (licence number-5,501,811,254,585)[40] …”

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confidence: 99%

Design of Experiments Study on Scottish Wood Biochars and Process Parameter Influence on Final Biochar Characteristics

Jamal

Fletcher

2023

Bioenerg. Res.

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“…Based on elemental analysis in Table S2, the crystals mainly consisted of calcium oxide . Although the concentration of potassium was at the same level, this element did not seem to be enriched after combustion, so potassium in the smooth part could be transferred to elsewhere or vaporized directly during the thermal process. , …”

Section: Results and Discussionmentioning

confidence: 99%

Dynamic Transformations of Metals in the Burning Solid Matter during Combustion of Heavy Metal-Contaminated Biomass

Zha

Yaji

Zhu

et al. 2021

ACS Sustainable Chem. Eng.

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Combustion as an efficient and reliable method is widely used for metal-enriched biomass to achieve energy and metal recoveries, but there are emission risks of heavy metals in the flue gas and bottom ash that can give rise to secondary pollutions. To optimize such combustion processes, this work investigated the combustion characteristics of a kind of hyperaccumulator biomass and focused on the intermediate states and dynamic transformations of metals for the first time. A pseudo-in situ sampling method was used to collect the burning solid residues at different time intervals before further analysis. The conversions between elemental forms were revealed, and their conversion rates were also calculated. It was found that the transformation of metals was determined by their elemental natures, species distributions, and combustion progress where there was not a consecutive process but separated by several stages, which were related to (1) the release of volatile matters, (2) the formation and consumption of the char, and (3) the fixation by silicates. Based on the information of dynamic metal characteristics, a new strategy was proposed to optimize metal distribution by adjusting the combustion time of operations. The methodology introduced in this work will also help emission control and metal recovery for other metal-rich fuels.

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“…During thermal biomass conversion processes, onerous compounds are formed that limit the efficiency of combustion and heat exchange processes. The parameters that deteriorate the quality of biomass for combustion are the high content of sodium, potassium as well as calcium and magnesium [57,58]. The results obtained in own studies indicate a high variability of the chemical composition of the analyzed materials.…”

Section: Chemical Analyses Of the Investigated Materialsmentioning

confidence: 90%

Evaluation of Urban Tree Leaf Biomass-Potential, Physico-Mechanical and Chemical Parameters of Raw Material and Solid Biofuel

et al. 2021

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The paper presents the results of research aimed at evaluating the possibility of using selected tree leaf species to produce solid biofuels. The possibility of production of qualitative solid biofuels from urban tree leaves meets the expectations of the municipal sector. Collection of tree leaves in urban areas is very often necessary for road safety reasons, the need to collect biomass rich in dust and pollution as well as biomass infested with pests. The production of solid biofuels from tree leaves allows for effective management of this raw material with energy recovery. The performed research indicates such a possibility, and the obtained ash is used as a soil improver. The conducted research showed that the biomass of leaves of five tree species used in the experiment can be a source of raw materials for production of qualitative biofuels. The obtained pellets were characterized by properties comparable to those of classical wood pellets. The lower heating value of the obtained pellets ranged from 14.5 to 15.5 MJ∙kg−1. Physical properties of the obtained pellets described by bulk density (BD 600–660 kg∙m−3), mechanical durability (DU 90–96%), moisture (Mar 10–12.5%) indicate that these products can be used in existing combustion equipment. Preliminary analysis of the obtained ashes (determination of ash melting point, bulk density) indicates that they should not cause difficulties in ash removal systems from the combustion chamber.

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Release of potassium in association with structural evolution during biomass combustion

Cited by 18 publications

References 52 publications

Design of Experiments Study on Scottish Wood Biochars and Process Parameter Influence on Final Biochar Characteristics

Design of Experiments Study on Scottish Wood Biochars and Process Parameter Influence on Final Biochar Characteristics

Dynamic Transformations of Metals in the Burning Solid Matter during Combustion of Heavy Metal-Contaminated Biomass

Evaluation of Urban Tree Leaf Biomass-Potential, Physico-Mechanical and Chemical Parameters of Raw Material and Solid Biofuel

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