Torrefaction of sawdust in a fluidized bed reactor

Li, Hui; Liu, Xinhua; Legros, Robert; Bi, Xiaotao; Lim, C. Jim; Sokhansanj, Shahab

doi:10.1016/j.biortech.2011.10.009

Cited by 138 publications

(85 citation statements)

References 24 publications

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“…The use of inert bed materials is preferred in fluidized beds for proper heat transfer to the particles in the reactor [32]. However, a study by Li et al [31] proposes eliminating the use of inert material due to the contamination caused by fine broken bed materials that will elevate the ash content of the torrefied product. Therefore, use of any bed material or inert material, such as sand, was avoided in this research as well.…”

Section: Experimental Apparatus and Methodsmentioning

confidence: 99%

Thermal Pre-Treatment of Sewage Sludge in a Lab-Scale Fluidized Bed for Enhancing Its Solid Fuel Properties

Karki

Poudel

2018

Applied Sciences

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Thermal pre-treatment of non-lignocellulosic biomass, sewage sludge, using a lab-scale fluidized bed reactor was carried out in order to enhance its solid fuel properties. The influence of the torrefaction temperature range from 200-350 • C and 0-50 min residence time on the physical and chemical properties of the torrefied product was investigated. Properties of the torrefied product were analyzed on the basis of the degree of torrefaction, ultimate and proximate analysis, and gas analysis. An attempt was made to obtain the chemical exergy of sewage sludge. An elevated torrefaction temperature presented a beneficial impact on the degree of torrefaction and chemical exergy. Moreover, the effect of the torrefaction temperature and residence time on the elemental variation of sewage sludge exhibited an increase in the weight percentage of carbon while the H/C and O/C molar ratios deteriorated. Additionally, the product gas emitted during torrefaction was analyzed to study the pathway of hydrocarbons and oxygen containing compounds. The compounds with oxygen were emitted at higher temperatures in contrast to hydrocarbon gases. In addition, the study of various correlations for predicting the calorific value of torrefied sewage sludge was made.

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Section: Experimental Apparatus and Methodsmentioning

confidence: 99%

Thermal Pre-Treatment of Sewage Sludge in a Lab-Scale Fluidized Bed for Enhancing Its Solid Fuel Properties

Karki

Poudel

2018

Applied Sciences

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“…Such a definition is much more focused on the mass yield rather than energy yield and density change, which are of greater importance for energy conversion. Li et al (2012) observed a linear relationship between energy yield and mass yield. Although the authors claimed that the severity of torrefaction increases with an increase in energy yield, no explicit suggestion on severity was proposed.…”

Section: Introductionmentioning

confidence: 95%

An Index for Quantifying the Degree of Torrefaction

Basu¹,

Kulshreshtha²,

Acharya³

2017

BioResources

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Torrefaction, a thermochemical pre-treatment process, is used to enhance the properties of biomass to make it more compatible with solid fossil fuels. A quantitative index (TI) is proposed here to define the degree or quality of torrefaction especially for its use in the energy industries. Torrefaction index is defined as the ratio of energy density enhancement factor of the product at the specified condition to that at a reference condition, which is torrefaction at 300 °C for 60 min. The index, calculated for a wide range of data shows a linear dependence on torrefaction temperature. Numerical values of this index were in range of 0.93 to 0.95, 0.95 to 0.97, and 0.97 to 1.0 for light, medium, and severe torrefaction conditions, respectively. Based on a wide range of experimental data of woody biomass, two empirical correlations for mass and energy yields were developed. These correlations permitted prediction of TI without performing torrefaction of the biomass.

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“…However, untreated biomass possessed the characteristics of low energy density, high heterogeneity, high water content and difficult for preservation and size reduction, which make it hard to be utilized directly in pulverized firing systems [2]. Torrefaction, a thermo-chemical process, involves heating biomass in inert atmosphere at temperatures of 200-300°C , during which biomass undergoes dehydration and decarboxylation reactions [3]. The torrefied biomass contains high energy density, hydrophobicity and grindability, which can save significant cost in the transportation and size reduction, increase the efficiency in direct combustion [4], [5], and offer and constant output one.…”

Section: Methodsmentioning

confidence: 99%

“…Mass yield (%) = (Mass torrefied sample /Mass raw sample ) × 100% (1) Energy yield (%) = (Mass yield×HHV torrefied )/HHV raw sample (2) Energy density (-) = Energy yield/Mass yield (3) As shown in Fig. 6, higher moisture content and reaction time led to lower mass and energy yield but higher energy density in the torrefied solid, which could be due to the escape of volatiles with low heating values.…”

Section: Characteristics Of the Torrefied Biomassmentioning

confidence: 98%

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Effects of Microwave － Induced Torrefaction on Waste Straw Upgrading

Lin¹,

林怡利²

2015

IJCEA

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Abstract-This study focused on upgrading waste straw by developing the technology of microwave-imduced torrefaction and investigating the key operating parameters to improve the energy density and hydrophobicity of biomass for better feedstock for the production of renewable energy. The experiments were conducted under inert environment and atmospheric pressure in a fixed-bed batch reactor putting in a self-designed microwave facility. Factors including microwave power (250 to 450 W), reaction time (10 to 30 min) and moisture content (8 to 50%) were evaluated and the torrefaction temperature was monitored and controlled in the range of 200 to 300 ℃. It was found that the shape and fullness of the reactor as well as the position and direction of the thermocouple in the microwave facility significantly affected the efficacy of microwave-induced torrefaction, while the influences of nitrogen flow-rate and moisture content of the biomass were negligible. With the increase of microwave power from 250 to 450 W, the content of fixed carbon and ash, higher heating value (HHV) and energy density increased in the torrefied straw. TGA and DTG confirmed the evaporation of moisture as well as the decomposition of hemicellulose and cellulose in biomass structures, and microwave power was the key factor affecting the torrefaction temperature so as to the energy yield and density of torrefied biomass. Straw torrefied under 450 W for 30 min showed characteristics similar to those of blended coal with HHV approaching to that of bituminous coal. With further optimization of microwave torrefaction parameters (power and reaction time), torrefied straw has potential for the substitution of coal used in pulverized coal-fired furnace.Index Terms-Microwave-induced torrefaction, rice straw, energy density, thermogravimetric analysis.

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Torrefaction of sawdust in a fluidized bed reactor

Cited by 138 publications

References 24 publications

Thermal Pre-Treatment of Sewage Sludge in a Lab-Scale Fluidized Bed for Enhancing Its Solid Fuel Properties

Thermal Pre-Treatment of Sewage Sludge in a Lab-Scale Fluidized Bed for Enhancing Its Solid Fuel Properties

An Index for Quantifying the Degree of Torrefaction

Effects of Microwave － Induced Torrefaction on Waste Straw Upgrading

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