Torreﬁed Biomass Pellets—Comparing Grindability in Different Laboratory Mills

Khalsa, Jan Hari Arti; Leistner, D.; Weller, Nadja; Darvell, L.I.; Dooley, Ben

doi:10.3390/en9100794

Cited by 22 publications

(6 citation statements)

References 23 publications

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“…As expected, the specific grinding energies increases strongly with the integration time. The values determined here are similar to values obtained in other studies at 8.23 kWh/ton (Khalsa et al, 2016). For comparison, grinding characteristics of PRB were also studied with power vs. time results for a 200 g PRB coal sample shown in Figure 7.…”

Section: Grinding Energysupporting

confidence: 73%

Properties of Torrefied U.S. Waste Blends

Zinchik

Kolapkar

et al. 2018

Front. Energy Res.

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Power generation facilities in the U.S. are looking for a potential renewable fuel that is sustainable, low-cost, complies with environmental regulation standards and is a drop-in fuel in the existing infrastructure. Although torrefied woody biomass, meets most of these requirements, its high cost, due to the use of woody biomass, prevented its commercialization. Industrial waste blends, which are also mostly renewable, are suitable feedstock for torrefaction, and can be an economically viable solution, thus may prolong the life of some of the existing coal power plants in the U.S. This paper focuses on the torrefaction dynamics of paper fiber-plastic waste blend of 60% fiber and 40% plastic and the characterization of its torrefied product as a function of extent of reaction (denoted by mass loss). Two forms of the blend are used, one is un-densified and the other is in the form of pellets with three times the density of the un-densified material. Torrefaction of these blends was conducted at 300 • C in the mass loss range of 0-51%. The torrefied product was characterized by moisture content, grindability, particle size distribution, energy content, molecular functional structure, and chlorine content. It was shown that although torrefaction dynamics is of the two forms differs significantly from each other, their properties and composition depend on the mass loss. Fiber content was shown to decrease relative to plastic upon the extent of torrefaction. Further, the torrefied product demonstrates a similar grinding behavior to Powder River Basin (PRB) coal. Upon grinding the fiber was concentrated in the smaller size fractions, while the plastic was concentrated in the larger size fractions.

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Section: Grinding Energysupporting

confidence: 73%

Properties of Torrefied U.S. Waste Blends

Zinchik

Kolapkar

et al. 2018

Front. Energy Res.

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“…This is determined by the density of the polymers the cell wall consists of, i.e., cellulose and hemicellulose [93][94][95]. During torrefaction this structure is effectively broken down, but also significant part of hemicellulose is lost due to thermal decomposition [19,22,66,96]. Nonetheless, true density reported for particles after torrefaction, can be higher, ranging between 1525 kg/m 3 and 1640 kg/m 3 [77].…”

Section: Resultsmentioning

confidence: 99%

“…Closed containers were subsequently inserted into hot laboratory furnace, pre-heated to 300 • C. Torrefaction was performed, in duplicate, with two distinct residence times of 15 min and 30 min, in order to obtain distinctly different samples, with respect to the severity of the torrefaction process. Temperature and residence time were selected based on a typical range of torrefaction conditions, reported in the literature [4,8,[23][24][25][26][65][66][67][68]. Selection of the temperatures from the higher end and residence time from lower end of reported conditions was dictated by the way these parameters influence productivity of torrefaction reactors.…”

Section: Torrefaction and Pelletizingmentioning

confidence: 99%

Influence of Torrefaction and Pelletizing of Sawdust on the Design Parameters of a Fixed Bed Gasifier

et al. 2020

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Gasification of biomass in fixed bed gasifiers is a well-known technology, with its origins dating back to the beginning of 20th century. It is a technology with good prospects, in terms of small scale, decentralized power co-generation. However, the understanding of the process is still not fully developed. Therefore, assessment of the changes in the design of a gasifier is typically performed with extensive prototyping stage, thus introducing significant cost. This study presents experimental results of gasification of a single pellet and bed of particles of raw and torrefied wood. The procedure can be used for obtaining design parameters of a fixed bed gasifier. Results of two suits of experiments, namely pyrolysis and CO2 gasification are presented. Moreover, results of pyrolysis of pellets are compared against a numerical model, developed for thermally thick particles. Pyrolysis time, predicted by model, was in good agreement with experimental results, despite some differences in the time when half of the initial mass was converted. Conversion times for CO2 gasification were much longer, despite higher temperature of the process, indicating importance of the reduction reactions. Overall, the obtained results could be helpful in developing a complete model of gasification of thermally thick particles in a fixed bed.

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“…Torrefaction is a slow pyrolysis process at moderate temperature (200‐300C°) usually used as biomass pre‐treatment prior to further process to generate energy or bio‐fuel 1 . The resulting solid product is intermediate between wood and charcoal, and exhibits certain advantages for energy purposes, when compared to the raw biomass as a decreased hygroscopicity, 2 dimensional stabilization, 3 a greater biological decay resistance, 4 increase in carbon content 5 occurring higher calorific values and energy density 6 and a decrease in the mechanical properties and principally resilience reducing its grinding 7 and transport energy cost 8 . Although there are various parameters such as operation conditions (temperature and residence time), reactor type, and heating rate that have an impact on the process, their optimizations are not considered enough by researchers 9…”

Section: Introductionmentioning

confidence: 99%

Modeling mass loss of biomass byNIR‐spectrometryduring the torrefaction process

et al. 2020

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Summary When biomass is thermally treated, the enrichment of carbon in the remaining “green coal” is correlated with the temperature and duration. Other properties related to the energetic properties of the torrefied biomass are closely related to chemical modifications and correlated to the material mass loss occurring during the thermal degradation. The possibility of using near infrared spectrometry has been investigated to predict the mass loss of Pinus sylvestris wood torrefied at temperatures ranging from 220°C to 300°C with durations varying from 1 minute to 10 hours. A first mass loss prediction model (NIR‐260) associated with the mean torrefaction temperature of 260°C was developed, and appeared suitable only for this temperature due to specific chemical reactions rate. A second model (NIRS‐All), using all available data was constructed and showed an accurate mass loss prediction, for both low (220°C) and high temperatures (300°C). The main differences between NIRS‐260 and NIRS‐All models are mainly attributed to the thermal modification of hemicelluloses and cellulose fractions occurred during the wood torrefaction. The results showed near infrared spectrometry combined with multivariate calibration modeling have potential utility in an industrial context as a standardized continuous method to figure out the mass loss of biomass during torrefaction by a rapid characterization. Novelty Statement The novelty concerns the use of the Near Infrared Spectrometry (NIRS) combined with multivariate calibration modeling as a standardized method for determining the mass loss biomass during torrefaction by a rapid and nondestructive characterization. A model was constructed and showed an accurate mass loss prediction, for both low (220°C) and high temperatures (300°C). Near infrared spectrometry have potential utility in an industrial context as a standardized continuous method.

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Torreﬁed Biomass Pellets—Comparing Grindability in Different Laboratory Mills

Cited by 22 publications

References 23 publications

Properties of Torrefied U.S. Waste Blends

Properties of Torrefied U.S. Waste Blends

Influence of Torrefaction and Pelletizing of Sawdust on the Design Parameters of a Fixed Bed Gasifier

Modeling mass loss of biomass byNIR‐spectrometryduring the torrefaction process

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