Comparative Assessment of Wet Torrefaction

Bach, Quang‐Vu; Tran, Khanh-Quang; Khalil, Roger Antoine; Skreiberg, Øyvind; Seisenbaeva, Gulaim A.

doi:10.1021/ef401295w

Cited by 146 publications

(68 citation statements)

References 58 publications

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“…As shown in the table, the ash content of the neutral-processed sawdust sample (SN) decreased by 55% compared to the original sawdust. This agrees with the work of Bach et al, [14] who found a similar decrease in ash content during wet torrefaction of biomass. Presence of ash, usually in the form of alkali metals, is often responsible for boiler and heat-exchanger fouling during biomass combustion; hence the decrease in ash content during the production of SN showed that hydrothermal torrefaction of wet biomass may address this problem.…”

Section: Resultssupporting

confidence: 93%

High temperature pyrolysis of solid products obtained from rapid hydrothermal pre-processing of pinewood sawdust

Onwudili

Nahil

et al. 2014

RSC Adv.

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A sample of pinewood sawdust was rapidly pre-processed in a torrefaction-type procedure, separately in subcritical water (neutral) and with added Na 2 CO 3 (alkaline compound) and Nb 2 O 5 (solid acid) in a batch reactor. The original sawdust and the three friable solid recovered products from the hydrothermal procedure were characterized in detail. The solid recovered products gave higher C/O and C/H ratios, higher calorific values and reduced moisture contents compared to the original sawdust. The four solid samples were then subjected to rapid high temperature pyrolysis in a fixed-bed reactor to investigate the effect of the pre-processing routes on the yields and compositions of pyrolysis products. With increasing pyrolysis temperature, the pre-processed samples produced more CO and H 2 , far more char and less tar than the original sawdust. The trends in the composition of gases and the yields of char suggested a combination of Boudouard reaction and CO 2 dry reforming as the predominant reactions during pyrolysis. For all samples, increased temperature led to reduced tar production with an increase in the aromatic oxygenates and aromatic hydrocarbons contents of the tar. At 800 °C, the ratio of aromatic hydrocarbons increased dramatically particularly from the sample pre-processed with Nb 2 O 5 indicating possible deoxygenation catalysis.

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Section: Resultssupporting

confidence: 93%

High temperature pyrolysis of solid products obtained from rapid hydrothermal pre-processing of pinewood sawdust

Onwudili

Nahil

et al. 2014

RSC Adv.

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“…In this introduction, we discussed the general goals and possible routes for biomass conversion and biorefineries with attention to the possibilities of 30 Chapter 2 using high-pressure CO 2 and CO 2 -H 2 O. These high-pressure systems have shown to be beneficial in multiple steps during the biomass conversion chain and offer the added benefit of being non-toxic, green and renewable solvents.…”

Section: Resultsmentioning

confidence: 99%

“…7 Dry torrefaction, sometimes referred to as a mild pyrolysis, is performed under an inert environment at atmospheric pressure with a retention time around one hour at low temperatures (200 1C to 300 1C or 180 1C to 260 1C in case of wet torrefaction (WT)). 29,30 In both conditions the main product is bio-char or bio-coal, which is used as a feedstock for combustion or gasification. The advantage of this char over raw biomass is that its characteristics are more stable and that it has a higher energy density, which makes its transportation less environmentally and economically intensive.…”

Section: Main Biorefinery Processesmentioning

confidence: 99%

Introduction to High Pressure CO2 and H2O Technologies in Sustainable Biomass Processing

Questell‐Santiago

Luterbacher

2017

High Pressure Technologies in Biomass Conversion

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Biomass is an attractive source of renewable carbon-based fuels and chemicals and their production is envisaged within the framework of integrated biorefineries. Multiple research efforts to make biorefineries more economically competitive and sustainable are ongoing. In this context the use of high-pressure CO2 and CO2/H2O mixtures for biomass conversion is especially attractive. These mixtures are cheap, renewable, environmentally benign and allow tuning of various processing parameters by varying temperature, pressure and CO2 loading. This chapter presents a broad introduction of the principal processes and conversion routes being considered within biorefineries, and how high-pressure CO2 and CO2/H2O mixtures could help address certain challenges associated with biomass conversion. Some of the principle advantages associated with high-pressure CO2 and CO2/H2O mixtures that we highlight here are their abilities to act as green substitutes for unsustainable solvents, to enhance acid-catalysed reaction rates by in situ carbonic acid formation, to reduce mass transfer-limitations, and to increase access to substrates and catalysts. We discuss these advantages in the context of the trade-offs associated with implementing large-scale high-pressure systems including safety concerns and increased capital costs. With this introduction, we highlight both the principal benefits and challenges associated with the use of high-pressure CO2 and CO2/H2O mixtures, which are further detailed in subsequent chapters.

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“…The process, which is exothermic, generates three main products: gases, aqueous chemicals and a solid residue (hydrochar) [81] which is the main product of WT accounting for up to 88% of the mass and almost 90% of the energy in the raw biomass [82]. The mechanisms involved in the WT of biomass generally differ to the mechanism of the DT variant.…”

Section: Mw-induced Wet-torrefaction Of Biomassmentioning

confidence: 99%

The application of microwave heating in bioenergy: A review on the microwave pre-treatment and upgrading technologies for biomass

Kostas

Beneroso

Robinson

2017

Renewable and Sustainable Energy Reviews

253

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Bioenergy, derived from biomass and/or biological (or biomass-derived) waste residues, has been acknowledged as a sustainable and clean burning source of renewable energy with the potential to reduce our reliance on fossil fuels (such as oil and natural gas). However, many bioenergy processes require some form of pre-treatment and/or upgrading procedure for biomass to generate a modified residue with more suitable properties and render it more compatible with the specific energy conversion route chosen. Many of these pre-treatments (or upgrading procedures) involve some form of substantive heating of the biomass to achieve this modification. Microwave (MW) heating has attracted much attention in recent years due to the advantages associated with dielectric heating effects. These advantages include rapid and efficient heating in a controlled environment, increasing processing rates and substantially shortening reaction times by up to 80%. However, despite this interest, the growth of industrial MW heating applications for bioenergy production has been hindered by a lack of understanding of the fundamentals of the MW heating mechanism when applied to biomass and waste residues. This article presents a review of the current scientific literature associated with the application of microwave heating for both the pre-treatment and upgrading of various biomass feedstocks across different bioenergy conversion pathways including thermal and biochemical processes. The fundamentals behind microwave heating will be explained, as well as discussion of the imperative areas which require further research and development to bridge the gap between fundamental science in the laboratory and the successful application of this technology at a commercial scale.

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Comparative Assessment of Wet Torrefaction

Cited by 146 publications

References 58 publications

High temperature pyrolysis of solid products obtained from rapid hydrothermal pre-processing of pinewood sawdust

High temperature pyrolysis of solid products obtained from rapid hydrothermal pre-processing of pinewood sawdust

Introduction to High Pressure CO2 and H2O Technologies in Sustainable Biomass Processing

The application of microwave heating in bioenergy: A review on the microwave pre-treatment and upgrading technologies for biomass

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