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Soil amendment has recently been addressed as one of the promising applications of torrefied biomass, where the distribution of nutrients is a significant parameter of interest. The present study uses an x-ray fluorescence technique to elucidate the influence of torrefaction severity on the nutrient composition of biomass (e.g. rice husk). An increase in the extent of process severity leads to an enhancement in the fixed carbon content. Hence, the variation in nutrient composition is analyzed with respect to changes in the fixed carbon content. Results reflected that variation of nutrients with increasing fixed carbon content does not follow a uniform trend. It signifies the need for understanding the effect of process conditions, chemical forms, and interactions among the elements on the release of compounds containing nutrients. Enrichment of P, Fe, Mn and Zn, and reduction of K, Ca, S, Cl, Cu, Ni, Si, Sr, Ti, and Br have been observed in the solid product obtained after torrefaction. Concentration of Si followed K and P are maximum in all samples. K, Cl, S, and Br loss occurs significantly because of relatively lower stability in the torrefaction temperature range. The present findings would be helpful in selecting the conditions required to produce torrefied biomass to amend a specific soil type for a particular crop. [ABSTRACT FROM AUTHOR]

Improving energy content and hydrophobic nature of woody biomass can be pursued through torrefaction. This gives torrefied biomass with a low bulk density, potentially increasing storage and transport costs. To overcome this issue, densifying the torrefied biomass is necessary. However, poor binding of particles makes densification challenging without using a binder. Therefore, the aim of this study was to investigate the physicochemical characteristics and techno-economic aspects of torrefied rubberwood biomass (TRWB) when pelletized using various cassava-based binders at different blending ratios. The selected binders included cassava starch (CS), cassava pulp (CP), and cassava chip (CC). Each binder at 5%, 10%, or 15% (wt.) was mixed with TRWB and water before pelletizing using a flat die machine. The results revealed that pelletizing TRWB with different cassava-based binders at various blending ratios influenced the physicochemical characteristics of the TRWB pellets, particularly dimensions, bulk density, fuel and atomic ratios, and energy content. The TRWB pellets demonstrated energy densities in the range of 7.95–11.39 GJ/m3, and their mechanical durability and fine content fell within acceptable ranges. The TRWB pellets maintained their shape during 120 min of water soaking, with water absorption levels varying by binder dose. The pelletizing ability, material, and energy costs of TRWB pellets depend on binder type and dose. CP can be applied as a binder for pelletizing torrefied rubberwood biomass. However, the mechanical durability of the product needs to be above the user requirement or standard. [ABSTRACT FROM AUTHOR]

Densification techniques allow biomass to be used in the energy mix with coal or as a direct replacement for coal as it is a renewable resource. Typically, biomass is bulky, so thermochemical methods, like torrefaction, reduce volatiles and moisture, leaving a higher composition of fixed carbon. After the torrefaction process, the torrefied biomass poses problems during handling, transportation, and storage because it consists of small (

This research addresses the urgent need for sustainable bioenergy alternatives, specifically evaluating betel nutshells as potential replacements for conventional biomass materials like coconut and palm fibers. The objective of the study was to gauge the inherent bioenergy potential of betel nutshells through an investigation of torrefaction under varying conditions, specifically temperatures ranging from 200-300 °C and residence times between 20-60 minutes in an inert environment. In this study, proximate analyses were utilized to investigate essential characteristics including moisture content, volatile matter, ash content, and fixed carbon, while a bomb calorimeter was used to determine their higher heating values. Initial results indicated that untreated betel nutshells had higher heating values and compositional similarities to coconut and palm fibers, highlighting their potential as a bioenergy source. Advanced torrefaction processes, involving increased temperatures and extended residence times, raised the fixed carbon content and reduced moisture in betel nutshells, thereby optimizing their higher heating value. This improvement is attributed to the decomposition of covalent bonds in the biomass structures, leading to the release of volatile compounds and consequent reductions in both oxygen-to-carbon and hydrogen-to-carbon ratios. Remarkably, at an operating temperature of 300 °C and a residence time of 60 minutes, torrefied betel nutshells reached a higher heating value of 25.20 MJ/kg, marking a substantial 31.39 % increase compared to untreated specimens. This study conclusively positions betel nutshells, typically considered agricultural waste, as competitive alternatives to traditional biomass resources in the biofuel industry.

Horse manure was pretreated by microwave wet torrefaction, and the effects of reaction solvent and torrefaction temperature on composition, thermal degradation characteristics, higher heating value, energy yield and morphology of horse manure were investigated. The results showed that the fixed carbon content and higher heating value of horse manure increased with the increase of temperature, while the energy yield decreased with the increase of temperature. Compared with the raw horse manure, the fixed carbon content increased significantly, the O/C ratio decreased by 28.00%, the higher heating value increased by 21.07%, and the energy yield obtained was 74.30% for torrefied horse manure obtained in pure water solvent at 200 ℃. Compared with the raw materials, the torrefied horse manure obtained in pure water and succinic acid has more ash content, while the sulfuric acid solvent can reduce the content of metal elements that form ash by 50.00%. Microwave wet torrefaction reduced the pyrolysis reactivity of horse manure but led to the improvement in combustion reactivity. The pore structure of the torrefied horse manure obtained in pure water solvent was more evident. The present work shows that microwave wet torrefaction can improve the quality of horse manure, in which the water is shown to be a more suitable reaction solvent than dilute acid at torrefied temperature of 200 ℃. [ABSTRACT FROM AUTHOR]

Densification techniques allow biomass to be used in the energy mix with coal or as a direct replacement for coal as it is a renewable resource. Typically, biomass is bulky, so thermochemical methods, like torrefaction, reduce volatiles and moisture, leaving a higher composition of fixed carbon. After the torrefaction process, the torrefied biomass poses problems during handling, transportation, and storage because it consists of small (<100 μm) disintegrated particles. Densification minimizes these problems through thermal compaction which produces integrated and larger (4 mm – 200 mm diameter) solid particles. This process can be done naturally (without any additives) or by adding binders which improve the torrefied biomass's physical, chemical, mechanical, and heating properties. This in turn reduces any costs associated with handling/transportation and storage of the biomass before it is used for energy generation. Densification increases the biomass's energy content per unit volume thereby enabling coal substitution. Recent reviews on densification have mainly focused on the binding of coal fines, raw biomass, and some torrefied biomass. Reviews on the binding theories are also available. This current review focuses solely on the aspect of torrefied biomass densification and the factors associated with the process. Insights and recommendations for the possible application of an integrated biomass torrefaction and densification process were provided herein. In addition, the gaps in literature were identified to enable future research on the application of the process to realize innovative renewable energy production in industry. [ABSTRACT FROM AUTHOR]

This research addresses the urgent need for sustainable bioenergy alternatives, specifically evaluating betel nutshells as potential replacements for conventional biomass materials like coconut and palm fibers. The objective of the study was to gauge the inherent bioenergy potential of betel nutshells through an investigation of torrefaction under varying conditions, specifically temperatures ranging from 200-300 °C and residence times between 20-60 minutes in an inert environment. In this study, proximate analyses were utilized to investigate essential characteristics including moisture content, volatile matter, ash content, and fixed carbon, while a bomb calorimeter was used to determine their higher heating values. Initial results indicated that untreated betel nutshells had higher heating values and compositional similarities to coconut and palm fibers, highlighting their potential as a bioenergy source. Advanced torrefaction processes, involving increased temperatures and extended residence times, raised the fixed carbon content and reduced moisture in betel nutshells, thereby optimizing their higher heating value. This improvement is attributed to the decomposition of covalent bonds in the biomass structures, leading to the release of volatile compounds and consequent reductions in both oxygen-to-carbon and hydrogen-to-carbon ratios. Remarkably, at an operating temperature of 300 °C and a residence time of 60 minutes, torrefied betel nutshells reached a higher heating value of 25.20 MJ/kg, marking a substantial 31.39 % increase compared to untreated specimens. This study conclusively positions betel nutshells, typically considered agricultural waste, as competitive alternatives to traditional biomass resources in the biofuel industry. [ABSTRACT FROM AUTHOR]

This study aimed to enhance the thermal characteristics of rice husk biomass through torrefaction conducted in a fixed-bed reactor. A novel approach was employed by circulating the gas produced within the system, instead of using traditional nitrogen. The torrefaction process took place at temperatures ranging from 200 to 320 °C, with different residence times of 10, 20, and 30 min for heat exchange. Quantitative analysis of the torrefied biomass revealed several notable improvements. The higher heating value of the biomass increased significantly, reaching 23.69 MJ/kg at a temperature of 320 °C and a residence time of 30 min. This enhancement indicates the effectiveness of torrefaction in increasing the energy content of the biomass. Furthermore, the torrefied biomass exhibited a remarkable reduction in hygroscopicity, with reduction by as much as 92 wt% compared to raw rice husk biomass. This reduction implies that the torrefied biomass is more resistant to moisture absorption, making it more stable and suitable for various applications. The torrefaction process in the fixed-bed reactor yielded a torrefied biomass with a production yield of 76 wt% (RH-320, RT30). This yield showcases the potential of the employed technique for producing a substantial amount of high-quality torrefied biomass. The resulting biomass holds great promise for diverse applications. It can be utilized for industrial steam production, contributing to the efficient use of biomass resources. Moreover, it could serve as an alternative fuel source for biomass power plants, offering a sustainable energy solution. Overall, this study demonstrates the effectiveness of the proposed torrefaction method in enhancing the thermal characteristics of rice husk biomass. The improved energy content and reduced hygroscopicity make torrefied biomass a valuable resource for various industries, promoting the utilization of biomass as a renewable energy source. [ABSTRACT FROM AUTHOR]

[Display omitted] • The heat source in the self-heating torrefaction of dairy manure was determined. • A mathematical model for self-heating torrefaction was developed. • The conditions that induce self-heating of manure up to 300 °C were determined. • Higher pressure and lower ventilation induce self-heating at lower temperatures. A self-heating torrefaction system was developed to overcome the difficulties in converting high-moisture biomass to biochar. In self-heating torrefaction, the ventilation rate and ambient pressure must be set properly to initiate the process. However, the minimum temperature at which self-heating begins is unclear because the effects of these operating variables on the heat balance are not theoretically understood. The present report presents a mathematical model for the self-heating of dairy manure based on the heat balance equation. The first step was to estimate the heat source; experimental data showed that the activation energy for the chemical oxidation of dairy manure is 67.5 kJ/mol. Next, the heat balance of feedstock in the process was analyzed. Results revealed that the higher the ambient pressure and the lower the ventilation rate at any given pressure, the lower the temperature at which self-heating is induced. The lowest induction temperature was 71 °C at a ventilation rate of 0.05 L min−1 kg-AFS−1 (AFS: ash-free solid). The model also revealed that the ventilation rate significantly affects the heat balance of feedstock and drying rate, suggesting an optimal range for ventilation. [ABSTRACT FROM AUTHOR]

The pretreatment of biomass through torrefaction is an effective means of improving the fuel quality of woody biomass and its suitability for use in existing facilities burning thermal coal. Densification of torrefied biomass produces a fuel of similar energy density, moisture content, and fixed carbon content to low-grade coals. Additionally, if the torrefaction conditions are optimized, the produced torrefied pellet will be resistant to weathering and biological degradation, allowing for outdoor storage and transport in a manner similar to coal. In untreated biomass, lignin is the primary binding agent for biomass pellets and is activated by the heat and pressures of the pellet extrusion process. The thermal degradation of lignin during torrefaction reduces its binding ability, resulting in pellets of low durability not suitable for transportation. The use of a binding agent can increase the durability of torrefied pellets/briquettes through a number of different binding mechanisms depending on the binder used. This study gives a review of granular binding mechanisms, as they apply to torrefied biomass and assesses a variety of organic and inorganic binding agents, ranking them on their applicability to torrefied pellets based on a number of criteria, including durability, hydrophobicity, and cost. The best binders were found to be solid lignin by-product derived from pulp and paper processing, biomass tar derived from biomass pyrolysis, tall oil pitch, and lime. [ABSTRACT FROM AUTHOR]

Conversion of low value agricultural residues to better-quality products e.g. biofuel, bioproducts can solve the issues related to energy crisis as well as environmental challenges. Torrefaction, a thermochemical pretreatment was employed on canola residue (CR) to augment the physicochemical properties of biomass for heat and energy applications. In the present study, the effects of microwave torrefaction on canola residue have been investigated for the following operating parameters: microwave power (250–450 W), residence time (10–20 min), and feeding load (70–110 g). Box Behnken design method was used to design the experiments and find the interaction between process parameters. Both mass and energy yields diminished with rise in microwave power and torrefaction reaction time. The results show that the carbon content significantly increased with degree of torrefaction while oxygen content had a reverse trend, therefore the atomic ratio of torrefied biomass reduced remarkably. Torrefied biomass shows higher carbon percentages than that for the bituminous coal. In addition, a noticeable decrease in volatile matter was observed with growth in torrefaction severity and thus increased fixed carbon content. The higher heating value (HHV) was boosted up by 26% (promoted from 17.8 MJ/kg to 22.4 MJ/kg). HHV of highly torrefied canola residue is very close to bituminous coal. Fourier transform infrared spectroscopy (FTIR) analysis showed that surface functional groups for example OH, CH, and CO decreased with torrefaction severity indicating the improvement of hydrophobicity of torrefied biomass. Scanning electron microscopy (SEM) results represent a more porous structure at highest torrefaction conditions which happened due to thermal cracking and decomposition of lignin and decreased the grinding energy by 89% compared to that for raw biomass. Moreover, inductively coupled plasma-mass spectrometry (ICP) analysis data showed that concentrations of minerals, alkaline and other essential element amplified with degree of torrefaction. The influence of microwave power was the highest on properties of torrefied biomass, followed by residence time and feeding load. The optimum torrefaction conditions were found at 450W with 90 g feeding load for residence time of 20 min.

Torrefaction is commonly used to improve biomass properties, applications, and economy. The characteristics and subsequent applications of torrefied biomass are largely contingent on the organic compounds in parent biomass and their evolution during torrefaction. Yet, the evolution of organic compounds in biomass particularly minor components (e.g., polyphenols) is far less investigated for torrefaction. To address such issues, a superheated steam (SHS) boosted torrefaction process at different temperatures (200, 250, and 300 °C) and residence times (15, 30, and 60 min) was performed on spent coffee ground (SCG), which is an emerging biowaste and is rich in various organic compounds. Results found that both temperature and residence time determine SHS torrefaction performance. SHS torrefaction could effectively remove volatile matters to upgrade SCG for solid fuel. The relatively high content of N and S in torrefied SCG may negatively affect fuel quality but may benefit its adsorption of environmental pollutants. SHS boosted torrefaction could facilitate cellulose and lipids degradation compared to conventional torrefaction. Efficient reduction/removal of labile carbon and ecotoxic chemicals (e.g., phenols and caffeine) in SCG was successfully achieved with SHS torrefaction. As a result, SHS-torrefied SCG with higher biostability and lower phytotoxicity was evaluated as soil amendments and additives to soilless growing substrate. Implications for subsequent application by revealing the evolution of organic compounds during SHS torrefaction were discussed. This study highlighted the potentiality of SHS torrefaction as a pretreatment of biomass for versatile applications. [Display omitted] • The maximal HHV of SHS-torrefied SCG reached 29.68 MJ/kg. • Cellulose and hemicellulose are greatly decomposed by SHS torrefaction. • Crude protein and lipids are less affected during SHS torrefaction. • Polyphenols, flavonoids, and caffeine are efficiently removed during SHS torrefaction. • SHS-torrefied SCG may be utilized as fuel, soil amendment, or biosorbent. [ABSTRACT FROM AUTHOR]

This work describes the conversion of sugarcane leaves into biocoal with two thermal processes: wet torrefaction (subcritical water, 175–250 °C) and dry torrefaction (nitrogen atmosphere, 225–300 °C). The residence time was 30 min for both processes. The effects on physical and energy characteristics, including mass and energy yield, proximate and ultimate analyses, fiber analysis, higher heating value (HHV), structural parameters determined by Fourier-transform infrared spectroscopy, and O/C and H/C atomic ratios were used for comparisons. The results showed that increasing the reaction temperature lowers the mass yield; however, it also significantly improves the fuel ratio of torrefied samples. The highest HHV of wet and dry-torrefied samples were 23.31 and 22.07 MJ/kg, respectively. The best removal of ash and sulfur content was obtained under wet torrefaction. Moreover, wet torrefaction was recommended as a suitable process for hemicellulose depolymerization. At 250 °C, the wet-torrefied sample had the highest fuel ratio (0.48) and was suited for biomass co-firing. The finding that wet-torrefied samples reached the same range of lignite at lower reaction temperatures than dry-torrefied samples was particularly intriguing. Torrefaction at the temperatures below 250 °C did not prove to have a statistically significant effect on the energy properties of the dry-torrefied samples. Therefore, wet torrefaction is a promising process in the thermochemical conversion of sugarcane leaves into solid biofuel. [ABSTRACT FROM AUTHOR]

This study is the first report that focuses on investigating the effects of torrefaction on the bioenergy-related properties, combustion behavior, and potential emissions of banana leaf waste (BLW). Experiments were first conducted in a bench-scale fixed-bed reactor operating at light (220 °C), mild (250 °C), and severe (280 °C) torrefaction conditions to torrefy the raw BLW. Torrefaction pretreatments reduced the weight of the raw BLW by about 60%, but the resulting solid biofuel can preserve up to 77% of the energy content of the raw biomass. It was found that torrefied BLW contains more concentrated fixed carbon than the raw BLW, volatile matter content of up to 59.8 wt.%, and a higher HHV of up to 20.7 MJ kg−1 with higher concentrations of carbon, nitrogen, and ash. Bulk density increased 13.0% over the raw BLW, and the torrefied BLW became a solid biofuel with 51.5% greater energy density under the severe torrefaction condition. The upgrading of BLW by torrefaction enhanced its combustion performance in terms of comprehensive combustion, ignition, burnout, and flammability indices. Compared with commercial hard coal, BLW torrefied at the mild condition (250 °C) had lower potential emissions per unit of energy, 25.3% less CO2 emission, 3.1% less CO emission, 96.4% less SO2 emission, and 18.4% less dust emission, except for NOX emission. This study conclusively indicates that BLW after torrefaction has enhanced bioenergy-related properties, improved combustion performance, and reduced emissions potential, proving to be a promising method for its valorization. [ABSTRACT FROM AUTHOR]

Because of different heat mechanism, the temperature distribution inside a reactor has its own characteristic. This is the limitation to increase the capacity of the reactor. This idea led to modify fixed-bed reactor that has a limitation on nonuniform temperature distribution inside a reactor with increasing heat transfer area by setting thermosyphon tube since fixed-bed reactor has another limitation in capacity and heat loss. Therefore, modifying fixed-bed reactor to operate as semi-batch can fix the limitation and improve thermal efficiency of a reactor as well. In order to study the performance of the reactor for torrefaction process, analyzing the fuel properties of each torrefied biomass batch is necessary. The controlled variables of this research are the temperature of heating chamber, which are 350, 400 and 400°C with an allotted torrefaction time of 35 minutes per batch that is close to research condition of thermosyphon reactor fixed-bed type. Fuel properties analyzed in this research are high heating value (HHV), bulk density, and energy density. This research also recorded the temperature inside the reactor to determine the temperature distribution when operated as a semibatch reactor. From the results gathered, it was discovered that when the operating reactor reached a steady behavior, the torrefaction process increased to a high level. As seen in energy density ratio, it reached a high level because of the increase of HHV ratio, that is 1.182 - 1.412 for 350 - 450°C. The bulk density ratio is also very low, and the value is close to a herbaceous biomass type that is usually seen in woody samples. These factors cause such energy density ratio in high levels and intensity of such process inside the reactor. [ABSTRACT FROM AUTHOR]

Co-combustion characteristics of high and low ash lignites blended with raw and torrefied pine woodchips were studied by Thermogravimetric Analyzer (TGA) under air and oxy-fuel conditions. The lignites were blended with biomass samples at the mass fraction of 50/50 wt.%. Three heating rates of 10, 20, and 40°C/min were chosen, and the characteristic temperatures, including initial, ignition, and burnout temperatures, were obtained. In order to estimate the activation energies of the co-combustion of the blends, Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, and Friedman kinetic methods were employed. Additionally, to assess the summative behavior of the fuel blends, the relative error as a degree of synergism was calculated based on the difference between theoretical and experimental DTG profiles. It was seen that co-combustion of torrefied biomass with the low ash Orhaneli lignite in air resulted in the average relative error of 21.41%, indicating the maximum synergism for the blend. This value was 9.59% under oxy-fuel combustion atmosphere. Blending torrefied biomass with the high ash Soma lignite resulted in average relative errors of 1.34% and 1.45% under air and oxy-fuel combustion atmospheres showing an insignificant synergetic effect. An improvement in combustion performance was noticed under oxy-fuel combustion conditions. The average activation energy values for the blend of torrefied biomass and Orhaneli lignite were 54.47 and 112.48 kJ/mol under air and oxy-fuel combustion atmospheres, which were lower than that of the parent fuels indicating higher reactivity of the blends. This trend was not seen for Soma lignite. The associated uncertainty values for the FWO method were in the range of 3.57% to 12.45% making it a proper tool for obtaining the kinetic parameters. [ABSTRACT FROM AUTHOR]

A model-fitting method at a single heating rate (10 °C·min-1 ) was used to investigate the thermal kinetic characteristics of torrefied woody biomass. The kinetic parameters were examined for pine, oak, and bamboo samples with the order of the reaction set ranging from 0.1 to 0.5 and 1.0. Based on the thermogravimetric, derivative thermogravimetric, and derivative2 thermogravimetric curves obtained, the ranges at which substantial hemicellulose and cellulose pyrolysis occurs were set as the analysis range, and the kinetic parameters of each species were analyzed. The activation energy and pre-exponential factor were obtained at these analytical ranges using two differential methods (Friedman and Chatterjee-Conard) and an integral method (Coats-Redfern). Although there were numerical differences between the results of the differential and integral methods, the thermal properties of each sample exhibited a consistent trend. Softwood was found to have the highest reactivity and intermolecular collisions per unit weight during thermal decomposition. In the case of the torrefied oak and torrefied bamboo, considering that the carbon content and fixed carbon content were approximately 24% to 25% higher than the softwood, it is appropriate to consider the thermal characteristics of each species for producing a solid fuel based on the application. [ABSTRACT FROM AUTHOR]

Melina wood torrefied at 260 °C for 60 min was agglomerated with lean grade coal fines into composite briquettes using pitch as binder. Torrefied biomass (3%–20%) and coal fines (80%–97%) were blended together to produce the composite briquettes under a hydraulic press (28 MPa). The briquettes were cured at 300 °C. Density, water resistance, drop to fracture, impact resistance, and cold crushing strength were evaluated for the composite briquettes. The proximate, ultimate, and calorific value analyses were carried out according to different ASTM standards. Microstructural studies were carried out using scanning electron microscope and electron probe microanalyzer equipped with energy dispersive x-ray. Fourier Transform Infrared Spectrophotometer (FTIR) was used to obtain the functional groups in the raw materials and briquettes. The density of the composite briquettes ranged from 0.92 to 1.31 g/cm3 after curing. Briquettes with < 10% torrefied biomass has good water resistance index (> 95%). The highest cold crushing strength of 4 MPa was obtained for briquettes produced from 97% coal fines and 3% torrefied biomass. The highest drop to fracture (54 times/2 m) and impact resistance index (1350) were obtained for the sample produced from 97% coal and 3% torrefied biomass. The fixed and elemental carbons of the briquettes showed a mild improvement compared to the raw coal. The peaks from FTIR spectra for the briquettes shows the presence of aromatic C=C bonds and phenolic OH group. The composite briquettes with up to 20% torrefied biomass can all be useful as fuel for various applications. [ABSTRACT FROM AUTHOR]

The use of coal for energy generation is facing serious scrutiny because of environmental concerns. As a result, there is a growing global interest in biomass, a renewable and readily available energy source. However, the utilization of biomass comes with significant drawbacks, including its heterogeneity, low bulk density, and calorific value. Biomass also has a low energy content, high moisture, poor grindability, and high volatile matter, which affect its handling, bulk transportation, and storage. Torrefaction technology has been employed in previous works to improve the properties of biomass for subsequent handling and transportation and for low-cost energy generation. Since coal is a promising precursor for energy generation, it is imperative to compare the physicochemical properties of coal with that of torrefied biomass. Therefore, this study aims to conduct a comprehensive comparison between various grades of coal and torrefied biomass. The review revealed that torrefied biomass could replace coal, as its properties are similar to those of coal, except for high-grade coals. The proximate and ultimate analyses of coals (lignite and bituminous) were found to be comparable to various torrefied biomass materials. The fuel ratio (0.5–2.0), and higher heating values (16,100–19,000 kJ/kg) of coal and torrefied biomass were within the range useful for coal-fired plants. Additionally, ash analyses, ash fusion temperature, hygroscopic tendency, functional group study, and microstructural comparison were reviewed in this study. The results from various studies have shown close similarities with only small disimilarities in the fuel properties between coal and torrefied biomass. Therefore, torrefied biomass is proposed as a complimentary feedstock to coal in various applications. [Display omitted] • The similarity and disparity between torrefied biomass and coal are discussed. • Proximate, ultimate, calorific, and FTIR analyses of torrefied biomass and coal were discussed. • Fuel ratio, ash content, and grindability values of torrefied biomass and coal were discussed. • Present grade of coal with similar properties to torrefied biomass and application in thermal plants. • Recommend partial or total replacement of coal with torrefied biomass in co-fired plants. [ABSTRACT FROM AUTHOR]

Chemical looping gasification is an efficient technology to convert biomass into valuable syngas. The iron-based oxygen carriers are a promising option for large-scale commercial applications due to their low cost and environmentally-friendly properties. The present study aims at evaluating the performance of the syngas production from the chemical looping gasification of torrefied woodchips in a pilot-scale bubbling fluidized bed reactor using iron ore and ilmenite as oxygen carriers. The effects of the operating parameters were investigated in this study. The results show that an increase in operating parameters could favor the process performance. Carbon conversion efficiency and the yields accelerate at high operating conditions. Carbon conversion efficiency showed a maximum value of 91.42% for iron ore at the ratio of oxygen carrier-to-biomass of 6, while the gas yield reaches the peak at SBR of 1.4 for ilmenite. The addition of steam in biomass chemical looping gasification improves hydrogen production and syngas quality in the product gas. Despite ilmenite provides better performance for hydrogen production, it characterizes by a lower reactivity compared to iron ore. It is also found that iron ore performs better at lower values of steam-to-biomass ratios and temperatures, while ilmenite shows good results at higher those parameters. • Chemical looping gasification of torrefied woodchips using iron-based oxygen carriers was investigated experimentally. • Higher ratios of oxygen carrier-to-biomass do not favor syngas production. • Higher gasification temperatures significantly enhance the process performance. • The content and yield of H 2 in the product gas are proportional to the ratio of steam-to-biomas. • Superficial velocity considerably affects the performance of chemical looping gasification. [ABSTRACT FROM AUTHOR]

The utilization of lignocellulosic biomass is closely related to one of the renewable sources of energy. However, a few inherent properties of lignocellulosic biomass such as high moisture content, low density, high volume, and heterogeneous composition make it unfavorable for bulk transportation, storage, handling, and conversion. The pretreatment of biomass is found to resolve a few of the aforementioned limitations while increasing the conversion efficiency of lignocellulosic biomass into biofuels. This article reviews the opportunities, challenges, and state-of-art research on torrefaction as a widely used biomass upgrading technique for solid fuel production and thermochemical biomass conversion. Some notable applications of such pretreatments in high-value solid biofuel production, densification, combustion, co-firing, gasification, and metallurgy have been reviewed. The broad changes in physicochemical characteristics and structural chemistry of lignocellulosic biomass because of torrefaction have been thoroughly described. This review also comprehends the effects of different process parameters and operating conditions of torrefaction of lignocellulosic biomass to produce high-value solid fuel. This article attempts to highlight some recent advancements in biomass torrefaction technology concerning the fundamental characteristics of biomass and process operation and optimization as well as the evolution of physicochemical features of torrefied biomass. Lastly, the value-added industrial applications of torrefaction technology and torrefied biomass are also elucidated. [ABSTRACT FROM AUTHOR]

The aim of this research was to evaluate the changes in physico-chemical properties of agricultural residues (corn-cobs and rice husks) during torrefaction. Physical properties of the torrefied biomass pellets were analysed. The results showed that increasing the torrefaction temperature and time resulted in reduced moisture and volatile matter content of corn-cobs and rice husks. At the same time, fixed carbon, ash content and heating values were increased. The heating values of both torrefied fuels were in the range of 14.9-16.9 MJ kg-1, increased by about 16% to 21% from the raw biomass. The optimum treatment conditions were found to be in the range 200°C-250° C and 20 min. Physical properties of both torrefied pellet fuels were found to be enhanced, and closer to those required by the associated standard. The average bulk density and durability of torrefied pellets were between 1112 and 1226 kg m-3 and 91% and 94%, respectively. The water resistance and compressive strength were in the range 89%-92% and 140-156 kg m-3, respectively. The energy densities of corn-cob and rice husk torrefiled fuels were increased by 20.8% and 15.8% with compared to their original biomass inputs. [ABSTRACT FROM AUTHOR]

Combustion and oxy-fuel combustion characteristics of torrefied pine wood chips were investigated by Thermogravimetric Analysis (TGA). Three torrefaction temperatures (250, 300, and 350 °C) and two residence times (15 and 30 min) were considered. Experiments were carried out at three heating rates of 10, 20, and 40 °C/min. The isoconversional kinetic methods of FWO, KAS, and Friedman were employed to estimate the activation energies. The assessment of uncertainty in obtaining the activation energy values was also considered. The obtained results indicated that due to torrefaction, the O/C and H/C atomic ratios decreased, resulting the 300ºC-30 min and 350ºC-15 min torrefied biomass to be completely embedded in lignite region in van-Krevelen's diagram. Oxy-fuel combustion affected the decomposition of cellulose and lignin components of biomass while the impact on the hemicellulose component was negligible. The kinetic analysis revealed that with the evolution of conversion degree, the activation energy values increased during hemicellulose degradation, remained approximately constant during cellulose decomposition and showed a sharp decrease for lignin decomposition. The activation energy trends were comparable in both air and oxy-fuel combustion conditions, however slight changes in activation energy values were noticed. The highest activation energy value was obtained for 250ºC-30 min torrefied biomass at 183.40 kJ/mol and the lowest value was 72.93 kJ/mol for 350ºC-15 min biomass. The uncertainty values related to FWO method were lower than KAS and Friedman methods. The uncertainty values for FWO and KAS methods were at the range of 5–15%. • The torrefaction temperature effect was more significant than residence time. • Torrefaction resulted in decreased O/C and H/C atomic ratios. • Oxy-fuel combustion affected the decomposition of cellulose and lignin. • Activation energy values increased during the degradation of hemicellulose. • Activation energy values showed a sharp decrease during the decomposition of lignin. [ABSTRACT FROM AUTHOR]

Dependence on inert gas such as nitrogen during torrefaction is not favourable due to the burden in terms of operational costs. Therefore, various alternatives have been introduced to reduce or eliminate the dependence on inert gas. The present article seeks to review the various alternatives to inert torrefaction for viable solid fuel production. The details on non-inert torrefaction, including experimental setup, effect of various essential parameters, and major findings, are reviewed and discussed. The primary trends in the torrefaction field were extracted from previous studies, were compiled and presented in several tables and graphs. The review findings showed that temperature, residence time, gas type, gas velocity, heating rate, and particle size can affect the performance, physicochemical, and combustion properties of torrefied biomass. The degree of the effectiveness of each parameter also depends on the biomass type and shape. Based on the van Krevelen diagram, the various alternative techniques can produce competitive torrefied solid products with viable fuel properties compared to commercial coals and products torrefied under inert torrefaction conditions. Overall, it is expected that the number of alternative techniques can be implemented on a larger scale after certain modifications are performed. • Physical, chemical, combination of physical and chemical approaches are available. • Effect of temperature and residence time were frequently investigated. • Various alternative approaches can produce very competitive solid fuels. • Temperature of 270–300 °C and holding time of 30–120 min are preferred. • Several alternatives can be implemented on a larger scale after modifications. [ABSTRACT FROM AUTHOR]

Peat is the main type of peloid used in Polish cosmetic/healing spa facilities. Depending on treatment and origin, peat waste can be contaminated microbiologically, and as a result, it must be incinerated in medical waste incineration plants without energy recovery (local law). Such a situation leads to peat waste management costs increase. Therefore, in this work, we checked the possibility of peat waste upcycling to carbonized solid fuel (CSF) using torrefaction. Torrefaction is a thermal treatment process that removes microbiological contamination and improves the fuel properties of peat waste. In this work, the torrefaction conditions (temperature and time) on CSF quality were tested. Parallelly, peat decomposition kinetics using TGA and torrefaction kinetics with lifetime prediction using macro-TGA were determined. Furthermore, torrefaction theoretical mass and energy balance were determined. The results were compared with reference material (wood), and as a result, obtained data can be used to adjust currently used wood torrefaction technologies for peat torrefaction. The results show that torrefaction improves the high heating value of peat waste from 19.0 to 21.3 MJ × kg−1, peat main decomposition takes place at 200–550 °C following second reaction order (n = 2), with an activation energy of 33.34 kJ × mol−1, and pre-exponential factor of 4.40 × 10−1 s−1. Moreover, differential scanning calorimetry analysis revealed that peat torrefaction required slightly more energy than wood torrefaction, and macro-TGA showed that peat torrefaction has lower torrefaction constant reaction rates (k) than wood 1.05 × 10−5–3.15 × 10−5 vs. 1.43 × 10−5–7.25 × 10−5 s−1.

In this article, four types of agricultural waste with different amounts of each lignocellulosic type, including rice husk (RH), coconut husk (CH), cassava rhizome (CR), and corncob (CC) were torrefied under inert environment at 200 - 300°C for 30 min. Biochar properties were characterized by various techniques in order to investigate their yield, physicochemical properties, higher heating value (HHV), thermal decomposition behavior, and surface functional group. The experimental results show that yield, HHV, and energy yield (Ey) of biochar were depended significantly on both types of agricultural waste and treatment temperature. The values of those parameters ranged from 81.75 - 35.59%, 19.06 - 28.29 MJ/kg, and 51.34 - 86.22%, respectively. Fuel properties of agricultural waste were greatly enhanced by torrefaction at 300°C. Biochar from torrefied CC provides the highest fuel ratio (2.18) with lowest atomic ratios of O/C and H/C (0.18 and 0.67, respectively) and this is comparative with bituminous coal. The changes of these properties were mainly due to dehydration and deoxygenation reactions. Interestingly, agricultural wastes with high cellulose content (44.41%) could produce biochar with the maximum energy yield (86.22%). These results indicated that torrefaction was a promising technology for conversion of agricultural wastes to biochar as coal substitute material. [ABSTRACT FROM AUTHOR]

• Power level was a major parameter in affecting performance of torrefied products. • Dielectric materials and particle size affect significantly heating rate. • 150 to 250 W was sufficient to produce a good quality torrefied products. • Clean-products derived from microwave heating technique can be obtained. • Dedicated operating conditions in MW heating resulted in high EROI (6.1 to 34). Microwave (MW) heating offers numerous advantages over conventional heating. Its characteristics of fast internal heating, volumetric heating, and low energy consumption enable microwave torrefaction (MWT) of biomass to be performed. The purpose of this article is to review the current state of MWT of biomass. A brief explanation of MWT, including experimental setups and the effects of several important parameters, are reviewed and discussed. Potential future directions and challenges regarding MWT are also discussed. It is known that the MW power level, types of MW absorbers (catalyst), and particle size can significantly influence the performance of torrefied biomass in terms of energy and mass yields, mass loss, H/C and O/C ratios, fuel ratio, and high heating value. The effect of operating condition on products derived from MWT needs to be further investigated in order to make the technology feasible and reliable. Overall, MWT has the potential to serve as energy-efficient method to improve the performance of biomass. [ABSTRACT FROM AUTHOR]

Abstract The utilization of biomass has been increasing in recent years, how to achieve successful feeding of biomass into the different utilization systems is a common problem. Reliable information on flow properties are required for the design of storage, processing and handling equipment. In this paper, the flow properties of four representative agricultural biomass powders (soybean straw, corn straw, rice straw and rice husk) and their torrefied powders were investigated experimentally by two different testing methods (angle of repose test and packing properties test) with a powder synthetic characteristic tester. The effects of mean particle size, particle shape, biomass species and their interaction on different characterization parameters (angle of repose, bulk density, tapped density, Hausner ratio and compressibility index) were investigated. The results of the two different testing methods were compared, and it was found that Hausner ratio and compressibility index cannot always accurately characterize the flowability of biomass powders compared with angle of repose. Meanwhile, the effect of torrefaction pretreatment on the flowability of biomass powders was discussed. The results showed that torrefaction pretreatment can improve biomass powder flowability, however, it cannot change the relative relationship between the flowability of different biomass powders. Highlights • Flow properties of biomass powders useful for design and control were determined. • The results of two different testing methods were analyzed and compared. • Effects of main physical properties on biomass powders' flowability were discussed. • Effect of torrefaction on the flowability of biomass powders was studied. [ABSTRACT FROM AUTHOR]

The combined use of bio-fuels along with CO 2 capture techniques is the basis for the so-called negative emissions energy systems. In this paper, oxy-fuel combustion of two torrefied biomasses is experimentally investigated in a lab-scale entrained flow reactor. The torrefied biomasses are fired alone, and co-fired with coal (50%). Two oxygen concentrations (21% and 35%) and four steam concentrations are tested: 0% (dry recycle oxy-combustion), 10% (wet recycle oxy-combustion), 25% and 40% (towards the concept of oxy-steam combustion). The tests are designed to get the same mean residence time for all the fuels and conditions. Burnout degrees are significantly increased (up to 9 and 16 percentage points) when the share of torrefied biomass is raised, with a slightly better behavior of the torrefied pine in comparison to the torrefied agro-biomass. C-fuel conversion to CO 2 follows a similar trend to the observed for the burnout degrees. NO formation rates are reduced when oxy-firing torrefied biomass alone in comparison to the blends, with maximum diminutions of 16.9% (torrefied pine) and 8.5% (torrefied agro-biomass). As regards the effect of steam, the best results are found for the 25% H 2 O atmospheres in most of the cases, yielding maximum conversions along with minimum NO levels. • New oxy-combustion results for two torrefied biomasses (up to 35% O 2 and 40% H 2 O). • Replacements of coal by torrefied biomasses improve fuel conversion and reduce NO. • Torrefied pine wood shows better behaviour than torrefied agro-biomass. • Best results are detected in most cases when 25% CO 2 is replaced by H 2 O. • The extent of NO reduction caused by H 2 O significantly depends on the fuel rank. [ABSTRACT FROM AUTHOR]

Summary: Torrefied biomass is a commercial fuel, which is particularly produced from woody biomass via torrefaction and alternative to coal to reduce greenhouse gas emissions in the short term. In this study, torrefaction conditions of cotton stalk were optimised, and the effect of bulk density together with temperature and residence time on process yields and characterisation of torrefied cotton stalk was investigated. Response surface methodology using Box‐Behnken design was employed for the design of experiments and optimization. Cotton stalk was torrefied at a temperature between 260°C and 320°C, in 10, 35, and 60 minutes with bulk density of 125, 150, and 175 kgm−3. Temperature was the most effective parameter for the six responses (higher heating value, carbon content, hydrogen/carbon and oxygen/carbon ratios, mass loss, and energy yield). Besides, temperature/bulk density interaction was found to be significant for all responses whereas residence time/bulk density interaction was effective for process yields. The optimization results showed that more economical torrefied biomass with similar quality of lignite could also be produced under process conditions of 305°C‐32 minutes‐158 kgm−3. At this point, higher heating value and carbon content of product were calculated as 19.7 MJ kg−1 and 64%, respectively. [ABSTRACT FROM AUTHOR]

Abstract A synergistic scheme of co-gasification of wet sewage sludge and torrefied biomass was proposed in order to get the hydrogen-rich syngas, which could avoid the dual energy input for drying of wet sewage sludge and steam generation. Co-gasification behavior of wet sewage sludge and torrefied biomass was evaluated by using a general non-stoichiometric thermodynamic equilibrium model developed based upon the Gibbs free energy minimization. The tenary plot of C H O system was used to evaluate the theoretical carbon formation performance at thermodynamic equilibrium state. The effects of mixing ratio and torrefaction severity on carbon conversion ratio, compositions of dry syngas, and H 2 yield were also addressed. High mixing ratio of wet sewage sludge and high gasification temperature were required for the high carbon conversion ratio. The gasification temperature of 1100 K was a favorable level for the H 2 yield and energy input. The optimal mixing ratio range of wet sewage sludge for low and middle temperatures torrefied biomass samples was between 30% and 40%, while that for high temperature ones was approximately 55%. This work could provide a feasible technical route and basic data for the resource and energy utilization of sewage sludge and biomass. Highlights • Co-gasification of wet sewage sludge and torrefied biomass was proposed. • A thermodynamic equilibrium model for co-gasification process was established. • Effect of torrefaction severity on co-gasification behavior was identified. • Mixing ratio of wet sewage sludge was between 30 and 55% for high hydrogen yield. • 1100 K was determined as a suitable temperature for high hydrogen yield. [ABSTRACT FROM AUTHOR]

Highlights • Biomass torrefied via microwave heating enhanced both the quantity and quality of bio-oil. • Parameters optimization of catalytic microwave co-pyrolysis of biomass and LDPE for bio-oil. • Temperature and catalyst dosage were key factors influencing both bio-oil yield and selectivity. • The proportion of hydrocarbons was the highest (about 40%) in the bio-oils. Abstract This study aims to produce high quality bio-oil by microwave co-pyrolysis of torrefied biomass (rice straw) and low density polyethylene (LDPE) using ZSM-5 as a catalyst. A central composite experimental design was used to optimize the reaction condition by response surface methodology analysis. The effects of reaction temperatures and catalyst dosages on the product yield and chemical selectivity of bio-oil were investigated. Results suggested that bio-oil obtained from torrefied biomass contained a lower water content compared with the control.The major chemical compounds of bio-oil were hydrocarbons, ketones, phenols, esters and alcohols (∼80%).Bio-oils with high hydrocarbon content (∼40% in the bio-oil) were obtained in the development of this experiment. Quadratic models were used to predict the bio-oil yield and chemical selectivity of the bio-oil obtained during the reactions. [ABSTRACT FROM AUTHOR]

In biomass harvesting and fuel preparation processes, grinding causes a prominent energy consumption penalty, which results in an analogous cost impact. This is due to the fibrous and tenacious nature of biomass. Torrefaction of biomass makes it brittle, as it diminishes its fibrous nature and, hence, it enhances its grindability. Nevertheless, grinding costs are still important and increase with decreasing targeted particle size. Therefore, this study introduces a methodology for assessing the torrefied biomass grind size that is suitable for firing or co-firing with coal in existing pulverized fuel boilers. It examines combustion of biomass of different origins, herbaceous, woody, or crop-related. Biomass was torrefied for 30 min at 275 °C in nitrogen. It was subsequently ground and sieved to various size cuts, which reflect the mean widths rather than the lengths of these typically elongated particles. Subsequently, the particles were burned, one at a time, in a drop tube furnace (DTF) under high temperature and high heating rate conditions. Luminous burnout times were observed pyrometrically and cinematographically for a number of single particles from various size cuts. Such burnout times were then contrasted with those of individual coal particles in the size range of 75–90 µm, i.e., at the upper end of particle sizes burned in coal-fired boilers. Based on this comparison, the nominal sieve size of the examined torrefied biomass particles whose overall observed burnout times matched those of the 75–90 µm coal particles was determined to be 212–300 µm. Hence, to minimize the grinding cost of co-firing such torrefied biomass with coal in existing boilers, its finer pulverization may not be necessary. [ABSTRACT FROM AUTHOR]

Torrefaction improves energy density, grindability, and hydrophobicity of raw biomass for gasification and combustion. While literature focuses on single biomass torrefaction, industrial production is likely to be from biomass mixtures. To address this knowledge gap, we torrefied three raw biomasses (pistachio nutshells, feed corn stover, cherry pits) at 250 °C, as “pure” biomasses and in multiple component mixtures to understand if synergistic interactions during torrefaction impact oxidation behavior of resulting solid fuels. The combustion enthalpies of blended biomasses were well predicted by an additive function, whereby a blend's property was the mass-weighted average of each biomass' torrefied property. However, synergistic effects that enhanced devolatilization when biomasses were comingled during torrefaction led to systemically lower volatile matter contents and higher surface areas of resulting solid fuels. This synergistic behavior continues in terms of activation energy of oxidation of the torrefied samples. Co-torrefaction of biomass may lead to a solid fuel with predictable heat content, but synergistic effects lead to oxidation of blended streams at different rates and activation energies, with blends often having lower reactivities and higher activation energies than an “additive” prediction of pure fuel components. This is attributed to enhanced devolatilization among biomasses, leading to more condensed carbonaceous solids. [ABSTRACT FROM AUTHOR]

To develop a new integrated system for co-production of electricity and hydrogen with CO 2 capture, a biomass steam gasification (BSG) process integrated with an iron-based chemical looping hydrogen production (CLHP) system and a combined heat and power (CHP) system is presented and simulated using Matlab and Aspen Plus. The raw wood (RW) and torrefied wood (TW) are used as the feedstock of the BSG process to produce RW- and TW-derived syngas, respectively. The CLHP system operates with solid circulation and adopts two countercurrent moving bed reactors where detailed kinetic models are validated by experimental data from the literature. The CHP system uses a combination of a heat recovery steam generator (HRSG) and a series of steam turbine (ST) cycles to enhance the electricity efficiency and the overall system efficiency. To address the maximum syngas conversion and hydrogen yield of the BSG-CLHP-CHP system, the optimal results show that steam velocity of the moving bed oxidizer is a crucial parameter, which should be operated at less than 15 cm s −1 for RW-derived syngas and 8.7 cm s −1 for TW-derived syngas. Overall, based on a comparison of the BSG-CLHP-CHP system performance in terms of hydrogen thermal efficiency, overall system efficiency, and hydrogen yield between RW and TW, the predictions suggest that TW is obviously superior to RW. [ABSTRACT FROM AUTHOR]

The use of solid renewable fuels in domestic-scale boilers, DSB is especially common in places where the distribution of other renewable energy sources is strongly limited (mountain and foothill regions). High moisture content and limited ventilation have a destructive impact on wood pellets' stability. Torrefaction of biomass is recognized as a possible way to enhance the wood pellets' hardness under wet conditions. It was found that the maximal water uptake for torrefied biomass after its water immersion was only 18.7 wt%. In this work, the combustion performance and emission of main pollutants during the combustion of thermally–treated biomass are analyzed using two types of boilers: coal-fired 25 kW th (retort burner) and biomass-fired 10 kW th (pellets burner). The best results were obtained during the combustion of torrefied biomass in a 10 kW th DSB, i.e. emission of CO 218 g/GJ, SO 2 2.5 g/GJ, NO x 111 g/GJ, and particulates 10.5 g/GJ, boiler efficiency of 90.23%. The combustion of torrefied biomass met the requirement of a 5th-class boiler according to the PN-EN 303-5 standard. Thermally–treated biomass can be used as a substitute fuel in DSB. Nevertheless, the boiler construction can be improved to obtain lower emissions of CO. • Combustion of thermally-treated biomass in commercial-scale domestic boilers. • Combustion tests were carried out in 25 kWth (coal) and 10 kWth (biomass) boilers. • Coal and biomass can be substituted by thermally-treated biomass in domestic boilers. • The maximal water uptake of torrefied biomass (water immersion test) was only 18.7 wt%. • Torrefied biomass presented higher durability and hydrophobicity. [ABSTRACT FROM AUTHOR]

The utilization of CO2 neutral carbon instead of fossil carbon is one way to mitigate CO2 emissions in the steel industry. Using reactive reducing agent, e.g., bio-coal (pre-treated biomass) in iron ore composites for the blast furnace can also enhance the self-reduction. The current study aims at investigating the self-reduction behavior of bio-coal containing iron ore composites under inert conditions and simulated blast furnace thermal profile. Composites with and without 10% bio-coal and sufficient amount of coke breeze to keep the C/O molar ratio equal to one were mixed and Portland cement was used as a binder. The self-reduction of composites was investigated by thermogravimetric analyses under inert atmosphere. To explore the reduction progress in each type of composite vertical tube furnace tests were conducted in nitrogen atmosphere up to temperatures selected based on thermogravimetric results. Bio-coal properties as fixed carbon, volatile matter content and ash composition influence the reduction of iron oxide. The reduction of the bio-coal containing composites begins at about 500 °C, a lower temperature compared to that for the composite with coke as only carbon source. The hematite was successfully reduced to metallic iron at 850 °C by using bio-coal, whereas with coke as a reducing agent temperature up to 1100 °C was required.

The effects of adding ash-free coal (AFC) as a binder on the physical and chemical properties of coke were investigated to understand the mechanism of coke strength increase and to measure CO conversion reactivity. Two AFC samples (AFC_P and AFC_E) were first extracted from Indonesian low-rank coal. Torrefied biomass was also produced from woody biomass for use as an additive to AFC samples. Coke samples were then prepared by adding 3% AFC and 3% AFC + torrefied fuel. The coke strength was investigated by performing indirect tensile tests and 13 C NMR analyses. Coke reactivity was examined using thermogravimetric analysis and a coke reactivity test apparatus. The use of AFC as a binder increased the tensile strength of coke between 39% and 48%. Specifically, coke tensile strength was 2.32 MPa with AFC_P and 2.16 MPa with AFC_P + torrefied fuel; and 2.17 MPa with AFC_E and 2.10 MPa with AFC_E + torrefied fuel. The reactivity of the coke containing AFC + torrefied fuel was higher than that of the coke containing AFC alone. The coke produced with AFC_E + torrefied fuel had the highest reaction rate and average CO emission of 257,543 ppm. [ABSTRACT FROM AUTHOR]

This study examined the torrefaction performance of Jatropha-seed residue after mechanical screw-press extraction of oil (denoted as JME) at fixed torrefaction temperature (T r ) of 533, 553 and 573 K in the torrefaction time (t r ) range of 10–60 min. The characteristics results of torrefied JME (JME T ) indicated that the mass yield decreases while dry-basis high heating value (H HD ) increases with increasing T r and t r . At t r = 20 min or longer and T r of 533–573 K, the H HD of obtained JME T is suitable for B1/B2/D Taiwan power industry fuel requirement. In addition, the H/C and O/C atomic ratios of JME T are better (i.e., lower) than those of torrefied wood and close to those of lignite and sub-bituminous coal. The satisfactory energy densification (E D ) of about 1.3 can be achieved for Case 1 at higher T r of 573 K and shorter t r of 30 min with log severity factor (logSF) of 7.37 or Case 2 at lower T r of 553 K and longer t r of 50 min with logSF of 7.00. The results indicated that Case 2 exhibits a lower value of SF than Case 1 at the same level of satisfactory E D , which is more beneficial for the torrefaction of JME. [ABSTRACT FROM AUTHOR]

The study examined the modifications in the thermo-physical and chemical structure of Tectona grandis (TK) and Sorghum bicolour stalk residues that occurred during the process of torrefaction. The analytical techniques used are Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) alongside some basic data characterisation techniques. Data from specific FTIR spectra were used quantitatively in the evaluation of total crystalline and lateral order indices (TCI and LOI) for cellulose and syringyl to guaiacyl (S/G) ratio in lignin. The indices and the ratio were applied in monitoring modifications in cellulose crystallinity and lignin structure. The S/G ratio for untreated TK dropped significantly from 0.6 to 0.12 after torrefaction. An appreciable rise in the TCI and LOI was observed for both samples following the thermochemical conversion process. A distinct thermal decomposition pathway, which widen in discrepancy with increasing torrefaction temperature, was established between untreated and torrefied biomass residues via the TGA. The basic data analysis demonstrated a significant rise in the calorific value of torrefied biomass; approximately from an average of 19.1-26.8 MJ/kg. [ABSTRACT FROM AUTHOR]

Chemical looping combustion (CLC) is an emerging CO 2 capture technology utilizing two interconnected circulating fluidized beds (CFB). An oxygen carrier is oxidized in the air reactor and reduced in the fuel reactor. In comparison to a classic oxyfuel process, no air separation unit is required to provide the oxygen needed to burn the fuel. The solid fuel, such as coal or biomass, is gasified in the fuel reactor, and the products from gasification are oxidized by the oxygen carrier. This work presents results of 110 h autothermal and partial autothermal CLC operation with ilmenite and iron ore as oxygen carriers. Hard coal and a fuel blend of hard coal and torrefied biomass were used as fuels. The results show that the oxygen demand of the fuel reactor required for a complete conversion of unconverted gases was in the range of 27%. At the same time, the carbon capture efficiency was low in the present configuration of the 1 MW th pilot. This means that unconverted char left the fuel reactor and burned in the air reactor. The reason for this is that no carbon stripper unit was used during these investigations. Some possible modifications like an oxygen carrier with oxygen uncoupling, a lower fuel feeding point or a secondary fluidization of the fuel reactor could significantly enhance the carbon capture efficiency. [ABSTRACT FROM AUTHOR]