Effect Of Torrefaction Temperature Research Articles

Towards the production of 1,4:3,6-dianhydro-α-d-glucopyranose from biomass fast pyrolysis based on oxalic acid-assisted torrefaction pretreatment

Pyrolysis, a promising thermochemical conversion technique, can convert lignocellulosic biomass into various value-added products. Herein, the selective production of 1,4:3,6-dianhydro-α-d-glucopyranose (DGP) was achieved through fast pyrolysis of cellulose based on oxalic acid-assisted torrefaction (OAT) pretreatment. The mixture of cellulose and oxalic acid first underwent torrefaction, followed by fast pyrolysis to yield DGP. Simultaneously, the air atmosphere was considered to facilitate the formation of esterification intermediates, thereby promoting the formation of DGP. The effects of torrefaction temperature, oxalic acid amount, as well as pyrolysis temperature were carefully explored for DGP production. A yield of 9.6 wt% and a selectivity of 57.5 % for DGP were achieved from the micro-scale pyrolysis of cellulose under the optimized conditions. In lab-scale tests, the DGP yield reached 12.5 wt% from cellulose. The OAT-based pyrolysis was confirmed to be applicable to the waste cellulose-rich materials, with a DGP yield of 8.2 wt% from waste cotton and 6.0 wt% from spent paper in lab-scale experiments. Additionally, the OAT-based pyrolysis also showed the potential for poly-generation of DGP and formic acid at different stages.

Research on the pyrolysis mechanism of tobacco based on low temperature torrefaction

The temperature range of 100–220 °C is known to cause the volatilization of some volatile components and the pyrolysis of some unstable components in tobacco. However, there is a lack of research on the pyrolysis mechanism of tobacco at this temperature range. To address this gap, the present study employed an innovative cascade pyrolysis method based on stepwise heating to analyze the composition of tobacco's rapid pyrolysis products within this temperature range. The analysis was conducted at intervals of 30 °C. The study summarized the release characteristics of organics at different temperatures and analyzed the representative substances of various organic families. In addition, considering that tobacco has a unique composition compared to most biomass, the same five temperature points as they do in the cascade pyrolysis process were selected to torrefy the tobacco samples. These temperatures are lower than the conventional torrefaction temperatures typically used for biomass pretreatment. Multiple techniques were used to systematically analyze the composition, functional group structure, and thermal degradation characteristics of tobacco torrefied at different temperatures. Subsequently, the effect of torrefaction temperature on the release performance of products from tobacco pyrolysis at 650 °C was also studied. The results of this study not only contribute to a more comprehensive understanding of the pyrolysis mechanism of tobacco but also provide theoretical support for cigarette processing and tobacco waste utilization.

Valorisation of waste biomass and plastics toward light aromatics: Co-catalytic fast pyrolysis of torrefied bamboo and polyethylene over alkali and acid treated hierarchical HZSM-5

Light aromatics are extremely important building blocks which can be prepared from the co-catalytic fast pyrolysis (Co-CFP) of biomass and polyethylene. In this study, the bamboo was torrefied to remove part of oxygen element prior to pyrolysis, then being co-fed with polyethylene (HDPE, PE and LDPE) during CFP over alkali (NaOH and Na2CO3) and acid (H3PO4 and HCl) treated HZSM-5. 40.3% oxygen element in bamboo could be eliminated at torrefaction temperature of 300 °C. After the acid dealumination or alkali desilication treatments, the mesopore was creased in HZSM-5, transforming into hierarchical structure with larger pore size and lower acidity. The effect of torrefaction temperature, the species of alkali or acid solutions and their concentrations, the mass ratio of HDPE-to-torrefied bamboo, the CFP temperature on the yields of light aromatics was systematically discussed. The maximum yield of BTX was 4.39 × 108 a.u./mg which was obtained by Co-CFP of torrefied bamboo (250 °C) and HDPE at mass ratio of 1:2 with 800 °C over 0.2 M NaOH treated hierarchical HZSM-5. The aromatization reaction of olefins, the deoxygenation reaction of oxygenates, and the Diels-Alder reaction between furans and olefins were key reactions for the formation of BTX during Co-CFP of torrefied bamboo and polyethylene.

Experimental and numerical investigation on a solar-driven torrefaction reactor using woody waste (Ashe Juniper)

In this work, designs a novel solar-driven thermochemical conversion reactor to torrefy biomass waste (Ashe Juniper) for further pyrolysis applications. The effect of torrefaction temperature and residence time on the properties of biomass waste was investigated and results showed that torrefaction temperature dominates the properties of product compared to the effect of residence time. The highest energy yield (over 90%) was obtained at 210 ℃ while the highest energy densification (∼1.51) was achieved at 360 ℃. In addition, a two-step kinetic numerical model was used to analyze and predict the experimental process (kinetic rates) and results (C, H, and O contents) based on the experimental results. The analysis results showed that the predicted results are in good agreement with the practical results after torrefaction, indicating the feasibility of this numerical model for torrefaction and pyrolysis applications. The carbon footprint analysis showed that reduction effect of 1.3 ∼ 1.6 tCO2/ton-AJ can be obtained by torrefaction of Ashe Juniper. Finally, the prospects for future industrial applications of solar-driven torrefaction reactors discussed as one of affordable and clean energy.

The effect of torrefaction temperature and catalyst loading in Microwave-Assisted in-situ catalytic Co-Pyrolysis of torrefied biomass and plastic wastes

In the current study, the effect of torrefaction temperatures (125–175 °C) and catalyst quantity (5–15 g) on co-pyrolysis of torrefied sawdust (TSD) and polystyrene (PS) are investigated to obtain value-added products. The role of torrefaction in co-pyrolysis of TSD: PS was analyzed to understand the product yields, synergy, and energy consumption . As the torrefaction temperature increases, oil yield (48.3–59.6 wt%) and char yield (24.3–29 wt%) increase while gas yield (27.4–11.4 wt%) decreases. Catalytic co-pyrolysis showed a significant level of synergy when compared to non-catalytic co-pyrolysis. For the conversion (%), a positive synergy maximum (-2.6) exists at a torrefaction temperature of 175 °C and 15 g of KOH catalyst. To develop the model, polynomial regression-based machine learning was used to predict pyrolysisproduct yields and energy usage variables. The developed models showed significant prediction accuracy (R2 > 0.98), suggesting the experimental values and the predicted values matched well.

Effect of torrefaction on the evolution of carbon and nitrogen during chemical looping gasification of rapeseed cake

Chemical looping gasification (CLG) is a novel approach to efficiently convert rapeseed cake (RC) to tunable syngas and NH3. However, the low energy density of RC seriously hinders its utilization. Meanwhile, torrefaction is an effective pretreatment for biomass upgrading. Hence, the combination of torrefaction with CLG is proposed as an alternative technology to efficiently utilize RC. In this work, the effect of torrefaction temperature on the evolution behaviors of carbon and nitrogen in CLG of RC with Ca2Fe2O5 OC was systematically investigated using TG-FTIR. Results show that torrefaction can effectively improve the physiochemical properties of RC. The torrefied RC possesses higher energy density and HHV, and lower atomic H/C and O/C ratios. Additionally, higher torrefaction temperature can facilitate the thermal degradations of N-IN and labile NP, with the productions of NH3 and HCN. During CLG, the rise of OC/Fuel mass ratio can increase the yields of the major gases (CO2, CO, CH4, NH3 and HCN), owing to both the oxidative effect of the lattice oxygen (O*) and the catalytic effects of Fe3+ and Ca2+ in OC. Moreover, torrefaction pretreatment can improve the CLG behavior of RC and the optimal torrefaction temperature is 250 °C, attributing to the improvement of fuel stability after torrefaction. Besides, torrefaction can marginally reduce the yields of the major nitrogen species (NH3 and HCN). This is ascribed to both the more stable structure of heterocyclic-N and the insufficiency of H radical in the torrefied RC compared to the raw. These findings provide a feasible guidance for the effective insight in nitrogen evolution during CLG coupled with torrefaction, and thereafter for the efficient utilization of biomass.

Ammonia (NH3)/nitrogen (N2) torrefaction pretreatment of waste biomass for the production of renewable nitrogen-containing chemicals via catalytic ammonization pyrolysis: Evolution of fuel-N under a N2/NH3-rich atmosphere

To investigate the nitrogen migration and transformation mechanisms that produce high value-added N-containing chemicals, the NH3/N2 torrefaction pretreatments of waste biomass for the production of renewable N-containing compounds were explored, and the effects of torrefaction temperature (200, 225, 250, 275, 300 °C) on fuel properties, structure, crystallinity, surface functional groups and thermal kinetics were evaluated by element analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), fourier infrared spectroscopy (FTIR) and thermogravimetric analysis (TG-DTG). The effects of subsequent catalytic ammonization pyrolysis upgrading of the torrefied biomass with Co/HZSM-5/HZSM-5 catalysts under an NH3/N2 atmosphere on product yield and N-containing compound selectivity were also evaluated with GC/MS and UV-fluorescence spectrometry. Furthermore, nitrogen fixation and migration mechanisms were also proposed in depth. The results showed that NH3 torrefaction was more effective in enhancing N fixation and retarding the release of N-containing volatiles in torrefied biochar (0.26%–9.43%) and reducing the oxygen content (43.18%–21.81%) via Maillard reactions compared with N2 torrefaction. With increasing torrefaction severity, the N-containing compound content, higher heating values (HHV), deoxygenation ratio (DEO) and nitrogen-doping ratio (NDR) increased, which were much higher than those of conventional N2 torrefaction. Higher temperatures promoted the evolution of graphitic-N and oxidized-N and reduced pyrrolic-N and pyridinic-N group formation in torrefied biochar. The maximum content of N-containing compounds of 88.71% was obtained at a torrefaction temperature of 275 °C under NH3 pyrolysis coupled with the Co/HZSM-5 catalyst, and was achieved via substrate interaction with the -Co-O-Si- catalyst sites and Maillard reactions. Furthermore, the N2 atmosphere combined with the HZSM-5 catalyst significantly promoted the conversion of HC compounds (∼56.97% at 225 °C during N2 torrefaction), while the Co/HZSM-5 catalyst combined with the NH3 atmosphere significantly improved N-containing compound formation. NH3 pyrolysis facilitated the formation of pyrroles and pyrazines while reducing the formation of amides by deamination and dehydrogenation reactions. Cellulose was conducive to the transformation of pyrrole in NH3 pyrolysis, while lignin was conducive to the formation of aniline. These results could offer strategies to regulate nitrogen functional groups to enhance N-containing chemicals.

Effect of Torrefaction Temperature on Physical Properties of Biopellet from Variant Biomass Waste

Effect of Torrefaction Temperature on Physical Properties of Biopellet from Variant Biomass Waste

Effect of torrefaction temperature on spent coffee grounds thermal behaviour and kinetics

The paper aimed to investigate the influence of the torrefaction temperature (210, 235, 260 °C) on the kinetic and thermodynamic parameters, as well as the reaction mechanism during combustion of spent coffee grounds (SCGs). Non-isothermal thermogravimetric experiments were carried out at four heating rates, namely, 5, 7, 10, and 15 °C/min. Thermogravimetric (TG) and differential thermogravimetric (DTG) results showed torrefaction temperature firstly increases and then decreases the combustion reactivity, reaching the best value for the sample SCGs-235. Starink, Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) iso-conversional models, master plots method and the compensation effect method were used to calculate the combustion kinetic triplet of the samples. The activation energy of the samples decreased with torrefaction temperature increasing, from 199.76 kJ/mol to 168.91 kJ/mol (with the Starink model). All the combustions were best explained by a reaction order model whose order decreased with the elevated torrefaction temperature and the heating rate of the combustion process. Using kinetic parameters obtained from the Starink method, thermodynamic parameters (enthalpy, Gibbs free energy, and entropy) were also determined, showing that SCGs seemed to be more suitable for the torrefaction at 235–260 °C. The study findings can provide practical information for modelling and designing combustion reactors for clean biofuel production from SCGs.

Analysis of functionality distribution and microstructural characteristics of upgraded rice husk after undergoing non-oxidative and oxidative torrefaction

Rice husk, a typical agricultural by-product was used for experimental investigation on characterizing the variations in fuel behaviors before and after torrefaction performed under different conditions. The effects of torrefaction temperature (493, 543 and 573 K), atmosphere (argon, air and flue gas) and duration (30 and 60 min) on the compositional variation, microstructural evolution, functional group distribution and surface hydrophobicity were evaluated systemically through the utilization of elemental analysis, FTIR, Raman spectra, XPS and contact angle. Oxidative torrefaction expressed a tendency to improve the torrefaction efficiency and increase the carbon content in torrefied sample due to the simultaneous occurrence of volatile release, carbonization and surface oxidation. Oxidizing agents could accelerate the decomposition or conversion of surface hydrophilic groups during oxidative torrefaction process effectively, strengthening the hydrophobicity of torrefied sample significantly. Furthermore, partial oxidation and thermal degradation tended to promote the crack of condense aromatic structures synergistically, increasing the proportion of active structures in the torrefied rice husk. Simultaneously, some nitrogen atoms initially located inside the aromatic structures with high thermal stability would migrate to the edge rapidly during the oxidative torrefaction (N-Q → N-5 + N-6). In the process of air torrefaction, excessive oxidants would reduce the content of reactive structure and functional group with low thermal stability through severe oxidation reaction, reducing the quality of torrefied sample, especially at high temperatures. The results in this study illustrated that torrefaction performed in flue gas atmosphere at 573 K for 30 min was the optimum torrefaction condition for rice husk upgradation, and employing flue gas as the carrier gas for biomass torrefaction was more effective and economical than N2 and air in improving the fuel quality of rice husk.

Characteristics of bio-oil and biochar from cotton stalk pyrolysis: Effects of torrefaction temperature and duration in an ammonia environment

In this study, nitrogen-containing chemicals and nitrogen-rich biochar were prepared using ammonia (NH3) torrefaction pretreatment technology. The effects of temperature and duration of torrefaction on the characteristics of torrefaction and pyrolysis products were evaluated. The results indicated that when the torrefaction temperature was increased to 290 °C, the nitrogen content increased significantly from 0.98% to 6.85%. XPS analysis showed that the raw biomass mainly contained amide-N and pyrrole-N. As the torrefaction temperature and duration increased, quaternary-N formation was promoted, while amide-N, pyrrole-N, and pyridine-N were consumed. Potential nitrogen doping and transformation pathways during the ammonia torrefaction process were proposed. GC–MS analysis showed that ammonia torrefaction promoted the formation of pyridines, while reducing the content of oxygen-containing species. In addition, torrefaction duration had positive effects on the yield of nitrogen-containing chemicals.

Effect of torrefaction pretreatment on biomass chemical looping gasification (BCLG) characteristics: Gaseous products distribution and kinetic analysis

The biomass chemical looping gasification (BCLG) of torrefied spruce-pine-fir (SPF) sawdust with Fe2O3 was studied using thermogravimetry-mass spectrometry (TG-MS). The effects of torrefaction temperature and OC ratio on the BCLG were investigated. The thermal characteristics of torrefied SPF with Fe2O3 and the distribution of gaseous products were discussed. Thermogravimetric kinetics and gas release kinetics were implemented to understand the mechanism. The results showed the volatiles release intensity of the SPF reached the maximum when the torrefaction temperature was 270 °C. The solid–solid reaction performance between OC and biochar reached the highest as the OC fraction was 50 wt%. The thermogravimetric kinetics revealed the activation energy of the BCLG gained the minimum when the OC ratio was 50 wt%. Moreover, the increase of OC ratio and torrefaction temperature could improve the reactivity of biochar. The torrefaction affected the gaseous products distribution of the BCLG, which consequently promoted the H2/CO ratio of the syngas from 1.06 to 1.30. Meanwhile, the gas release kinetic analysis demonstrated the E(H2) made the minimum (88.66 kJ·mol−1) when the torrefaction temperature was 270 °C. All these indicate the torrefaction has a positive effect on the BCLG process.

Effects of torrefaction pretreatment and Mg-Al modified HZSM-5 catalysts on components distribution in bio-oils from camphorwood pyrolysis

Torrefaction pretreatment conducted at a low temperature is an important technique for refining the bio-oil and improving the production of some chemicals in the bio-oil (e.g. aromatic hydrocarbons). In this work, the effects of torrefaction temperature and catalysts on the yields of pyrolysis products and components distribution in the bio-oils were analyzed. The weak acid sites shifted to higher temperature as the HZSM-5 was modified by Mg2+ or Al3+. The catalytic pyrolysis from camphorwood was done at pyrolysis of 450 °C and torrefaction temperature of 200 °C. The catalysts remarkably influenced the yields of bio-oil and components distribution. The catalysts increased the production of phenols. The content of phenols in the resulting bio-oil exhibited the following trend: HZSM-5 < MgO-modified HZSM-5 < Al2O3-modified HZSM-5. In addition, the content of 2,6-dimethoxyphenol was the highest among all phenol components (5.58%). The production of aldehydes was remarkably improved by the Al2O3-modified HZSM-5, resulting in a maximum content of 8.21%. Thus the torrefaction temperature and catalysts would refine the bio-oil (such as the acid value decreased) and significantly improve the contents of components (such as D-allose, 2,6-dimethoxy-4-(2-propeny)-phenol, 1,2,4-trimethoxybenzene, and 2,6-dimethoxyphenol). The results provide a theoretical basis for the resource recovery of biomass.

Effect of torrefaction temperature and O2 concentration on the pyrolysis behaviour of moso bamboo

Five-year-old moso bamboo was torrefied under nitrogen and different oxygen concentrations of 3% to 9% and torrefaction temperatures of 200 °C to 300 °C. Mass yields of 31.7% to 96.6%, energy yields of 30.8% to 98.9%, and higher heating values (HHVs) in the range 18.8 to 27.1 MJ/kg were obtained. The torrefied sample was characterized by Fourier transform infrared spectrometry (FTIR). Under the different torrefaction temperatures and oxygen concentrations, hemicellulose and cellulose were thermally decomposed, which led to significant changes in the chemical functional groups of the raw and torrefied bamboo. The pyrolysis experiments on raw and torrefied bamboo were conducted using the pyrolyzer coupled with a gas chromatography/mass spectrometer (Py-GC/MS). According to the Py-GC/MS analysis, the pyrolytic bio-oil were mainly composed of acids, furans, phenols, ketones, aldehydes, esters, alcohols, and hydrocarbons. Higher torrefaction temperature reduced the relative contents of acids, ketones, furans, and aldehydes. However, lower torrefaction temperatures and moderate oxygen concentrations were optimal for the production of phenols and hydrocarbons.

Production of high quality empty fruit bunch pellet by water washing and torrefaction

EFB pellet is the high potential biomass for combustion process due to the relatively high heating value and the high availability in the Southern of Thailand. However, the containing of high unwanted minerals, especially K and Cl is the main drawback of EFB pellet which causing the ash fouling or/and slagging during the combustion. In this study, the high quality EFB pellets (low K, low Cl, high heating value) were produced by applying the water washing and torrefaction methods. For water washing treatment, the effect of water and acetic acid solution on the mineral content of EFB pellet was studied. In addition, the effect of torrefaction temperature (250, 280 and 300 °C) on the quality of EFB pellet was investigated. Results revealed that the ash content of the washed EFB decreased from 5.3 % to 3.0 % and 0.7 % by washing with tap water and acetic acid solution, respectively. Comparing with the raw EFB pellet, K and Cl in ash were significantly reduced by washing about 60 % and 88 %, respectively. Heating value of the EFB and washed EFB pellet were increased after torrefaction with the higher temperature. The water washed EFB pellet and torrefied at 300 °C gave the highest heating value about 24.3 MJ/kg. It was 33% increased HHV when comparing with raw EFB pellet.

Effect of Torrefaction Temperature, Residence Time and Particle Size on the Properties of Torrefied Food Waste

Municipal solid waste (MSW) in Malaysia mainly consists of food waste. As food waste is of organic compounds, its improper management may cause serious environmental issues, as it may produce greenhouse gases and polluting leachate. Alternative management of the food waste is through its utilization. However, the main issue in the utilization of food waste is its heterogeneity, whereby the diversified cooking methods, as well as food origin, emanates different characteristics. Hence, food waste needs to be pre-treated through the torrefaction process, which is a thermochemical method that converts it to biochar at a temperature between 200–300 °C in an inert environment. The main aim of this work is to evaluate the feasibility of food waste as a potential source of energy through the torrefaction process. The torrefaction of food waste was conducted in a vertical tubular reactor under an inert atmosphere. The results obtained from this study showed that as torrefaction temperature became more severe, the produced torrefied solid is more energy-dense, with apparent higher fixed carbon content and improved heating values. These findings imply that food waste may be able to be utilized as a solid biofuel, with fuel properties comparable to conventional fuels.

Fuel Properties of Torrefied Biomass from Pruning of Oxytree

The very fast growing Oxytree (Paulownia Clon in Vitro 112) is marketed as a promising new energy crop. The tree has characteristically large leaves, thrives in warmer climates, and requires initial pruning for enhanced biomass production in later years. We explored valorizing the waste biomass of initial (first year) pruning via thermal treatment. Specifically, we used torrefaction (‘roasting’) to produce biochar with improved fuel properties. Here for the first time, we examined and summarized the fuel properties data of raw biomass of Oxytree pruning and biochars generated via torrefaction. The effects of torrefaction temperature (200~300 °C), process time (20~60 min), soil type, and agro-technical cultivation practices (geotextile and drip irrigation) on fuel properties of the resulting biochars were summarized. The dataset contains results of thermogravimetric analysis (TGA) as well as proximate and ultimate analyses of Oxytree biomass and generated biochars. The presented data are useful in determining Oxytree torrefaction reaction kinetics and further techno-economical modeling of the feasibility of Oxytree valorization via torrefaction. Oxytree torrefaction could be exploited as part of valorization resulting from a synergy between a high yield crop with the efficient production of high-quality renewable fuel.

The Grindability of Biochars from Agroforestry Biomass Prepared under Different Torrefied Conditions

The torrefaction experiments of four biomass including agricultural biomass (corn straw (CS) and wheat straw (WS)) and forestry biomass (polar wood (PW) and cedar wood (CW)) were carried out in a fixed bed reactor at torrefaction temperature of 200-300°C and holding time of 10-60min, the effects of torrefaction temperature and holding time on biochar grindability based on the component analysis and the particle size distribution of ground biomass and biochars. The obtained results indicated that the mass fraction of ground biochar with particle size less than 150 μm increases with increasing torrefaction temperature, and the mass fraction of ground biochar with particle size less than 150 μm achieves 100%. The larger the λC, the better the grindability of biochar. The correlation between the grindability of the woody biochar and the λC is not as good as that of the straw biochar. The grindability of corn straw biochar and cedar wood biochar is improved with the increase of holding time at the same torrefaction temperature, however, the grindability of wheat straw biochar and polar wood biochar gets a little change, which can keep good grindability at higher torrefaction temperature large than 275°C.

TORREFIED BRIQUETTES OF SUGAR CANE BAGASSE AND EUCALYPTUS

ABSTRACT Torrefaction and briquetting are two techniques that improve the quality of the biomass and facilitate direct use as fuel. The objective was to evaluate the effect of torrefaction temperature on the properties of the compound briquettes made from sugar cane bagasse and Eucalyptus sawdust. After sample preparation and particle analyses, briquettes were produced with the mixture of the two biomasses, a total of five compositions (0, 25, 50, 75 and 100%) at 120 °C and pressure of 1500 PSI. Subsequently, the briquettes were torrefied at temperatures of 180, 220 and 260 °C, for a period of 15 minutes. According to the results, both biomasses of Eucalyptus sawdust and sugar cane bagasse showed potential for the production of briquettes. The torrefaction reduced hygroscopicity and increased the calorific value of compound briquettes. The ideal composition for the production of briquettes is 100% Eucalyptus. The composition of 50% Eucalyptus + 50% sugar cane bagasse is also a great option, as some bagasse parameters were excellent. 260 °C was the best temperature to promote energy savings.

Grindability of torrefied wood chips and wood pellets

Torrefaction of biomass improves the grindability of raw biomass by the transformation from a fibrous structure to a more brittle and friable, coal-like material. Torrefied biomass is a more desirable feedstock for co-firing applications, especially in existing coal-fired power plants. Therefore, measuring the grindability and the specific energy consumption are critical for understanding the comminution behavior of torrefied biomass, and thus selecting appropriate milling equipment. In this study, the effect of torrefaction temperature on the specific grinding energy consumption and the grindability of torrefied wood pellets and wood chips was investigated and compared with that of coal. The applicability of three well-known grinding equations (Kick, Rittinger and Bond) was studied for the torrefied biomass using a knife mill. The specific grinding energy of both torrefied wood chips and pellets linearly decreased with increased torrefaction temperature over a range of 250–290 °C. Rittinger's model was the best-fit for both wood chips (R2 = 0.72–0.90) and wood pellets (R2 = 0.67–0.76). When the intercepts were considered, the Rittinger's and Bond's equations fitted well with the experimental data (R2 = 0.79–0.99) for all torrefied biomass. The grindability of torrefied biomass was measured using the Hardgrove Grindability Index (HGI) and the International Organization for Standardization (ISO) grindability index. A relationship between the Bond Work Index (BWI), based on the Bond's theory and HGI was developed for wood chips and wood pellets. Contrary to HGI index, BWI decreased with an increase in torrefaction temperature. The grindability parameters developed for torrefied biomass can be used for modeling and selecting suitable milling equipment.