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[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]

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]

Flash pyrolysis gas yields from bituminous coal and torrefied biomass have been investigated in the temperature range between 873 and 1273 K for 22 different gas species simultaneously. Recording a larger number of species gives a more detailed insight into pyrolysis of solid fuels than it is provided by other studies in literature, where typically smaller numbers of species are tracked. As processes utilizing biomass are designed for lower process temperatures, literature data for biomass pyrolysis are scarce in the temperature range between 1023 and 1273 K. This work, aiming at investigating potential fuels for pulverized solid fuel combustion, approximates pyrolysis conditions in the ignition zone of actual power plant boilers, where possible. Thus, based on results of a literature review, an experiment was designed using a small-scale fluidized bed reactor (FBR) to simultaneously analyze the pyrolysis gas yields for 22 species and to close the temperature gap found for biomass. Small batches of pulverized torrefied biomass from poplar wood and pulverized Colombian bituminous coal (Mina Norte) were rapidly pyrolyzed in the reactor. The two fuels were chosen as exemplary conventional and alternative energy sources for pulverized fuel fired power plants. Experiments have been carried out under atmospheric pressure in pure nitrogen atmosphere. Product gas analysis was carried out by Fourier transform infrared spectroscopy (FTIR) including two different sampling techniques. As a novelty, offline measurements have been used exclusively to improve the gas species selection procedure and reliability of detection. In case of offline measurements, the gas flow to the FTIR gas cell is stopped and the gas is enclosed in the cell allowing longer scan times of the captured gas mixture and thereby enlarging the signal-to-noise ratio (SNR). In succession, regular measurements with continuous flow (online) were performed for the simultaneous quantitative analysis of total pyrolysis yields for 22 selected gas species. Obtained pyrolysis yields show good agreement with available literature data. The larger number of investigated species provides an extended data set also covering minor pyrolysis species, for which quantitative data are scarce. Additionally, trends in the gas yields for biomass agree well with those found by other authors outside the mentioned temperature gap between 1023 and 1273 K. [ABSTRACT FROM AUTHOR]

The adverse nature of biomass requires specific pretreatment processes to better utilize it in bioenergy applications, and torrefaction is one of the most recognized thermal pretreatment methods. In this regard, we studied the effect of torrefaction pretreatment on kinetics, reaction mechanism and heat flow during the pyrolysis of biomass by making a comparative analysis between the pyrolysis of dried and torrefied Eucalyptus wood. Torrefied biomass was produced at three temperatures, namely 250, 275 and 300 °C. Pyrolysis was performed at 700 °C. The char yield during pyrolysis increased from 22.39 percent to 36.34 percent when the torrefaction temperature was increased from 250 to 300 °C. Kinetic analysis showed that torrefied biomass has higher activation energy values than dried biomass. The reported activation energy values for dried biomass were within the range of 165–185 kJ/mol, and for the biomass torrefied at 300 °C they were within the range of 180–245 kJ/mol. We used two different approaches, namely master plots and kinetic compensation parameters, to identify the reaction mechanism. The results showed that torrefaction treatment had an effect on the reaction mechanism of the biomass pyrolysis. The reason could be the degradation of hemicellulose during torrefaction, and thereby the formation of smaller molecules during the pyrolysis of torrefied biomass. The heat flow data from differential scanning calorimetry (DSC) showed that pyrolysis started with exothermic reactions for dried samples, and endothermic reactions for torrefied samples. The results presented provide valuable insights into increasing the understanding of the pyrolysis of torrefied biomass. [ABSTRACT FROM AUTHOR]

The pyrolysis of native and torrefied stump materials was studied in the kinetic regime by means of a thermogravimetric analyzer operated in the non-isothermal fashion. Three different kinetic models applicable to biomass pyrolysis were evaluated for the collected data, which include a single-reaction model, two three pseudo-components models, and a distributed activation energy model (DAEM). It was shown that the single-reaction model was not suitable to simulating stump biomass pyrolysis. The other models including the three pseudo-components model with n = 1 and n ≠ 1, and the DAEM demonstrated very good fits between simulated and experimental curves. However, the three pseudo-components model with n ≠ 1 is recommended as the most suitable for simulation and prediction of kinetic behaviour of slow pyrolysis for both untreated and torrefied stump, considering that it offers the best fits to the experimental data and that the generated reaction orders are realistic, being slightly higher than unity. It appears that the torrefied stump has higher activation energy than its native material. The activation energy predicted for the native stump pyrolysis is in the range of 105.2–108.9 kJ/mol, 183.5–183.6 kJ/mol, and 40.3–48.01 kJ/mol for hemicelluloses, celluloses, and lignin, respectively. That for pyrolysis of the stump torrefied at 200 °C is 105.13–111.19 kJ/mol, 183.68–185.79 kJ/mol, and 40.49–50.70 kJ/mol, respectively. [ABSTRACT FROM AUTHOR]

We apply a biomass pyrolysis model, based on the model developed by Haseli et al. [4] , which can be used in combination with Direct Numerical Simulation. The pyrolysis model is combined with a model for particle tracking to simulate 3D turbulent particle-laden channel flow with biomass particles undergoing pyrolysis in nitrogen. Transfer of momentum, heat and mass between gas and particles are fully taken into account. The effects of this transfer are analyzed and quantified in terms of the delay in the conversion or pyrolysis time. The delay is shown to depend on the initial volume fraction (number of particles) and on the size of the particles. The two-way coupling effects are relevant at volume fractions >10 −5 . For a fixed volume fraction, gas–particle interaction induces a delay in the devolatilization, decreasing with increasing particle size. Using this model, we also performed simulations of realistic biomass particle size distributions in order to compare two-way and one-way coupling. [ABSTRACT FROM AUTHOR]

Highlights: [•] The first study of integrated microwave torrefaction and pyrolysis of corn stover. [•] Microwave torrefied pyrolysis favored phenols and hydrocarbons production. [•] Organic acids were significantly reduced in bio-oils. [•] Up to 26.7 area% hydrocarbons in the bio-oil were produced. [ABSTRACT FROM AUTHOR]

Highlights: [•] Biomasses were devolatilized at high temperatures and high heating rates. [•] Biomass decreases its reactivity after torrefaction. [•] The kinetic parameters of torrefied biomasses were determined. [•] CO and H2 are main released volatiles during devolatilization of torrefied biomass. [ABSTRACT FROM AUTHOR]

Abstract: Microwave pyrolysis of torrefied Douglas fir sawdust pellet was investigated to determine the effects of torrefaction on the biofuel production. Compared to the pyrolysis of raw biomass, the increased concentrations of phenols and sugars and reduced concentrations of guaiacols and furans were obtained from pyrolysis of torrefied biomass, indicating that torrefaction as a pretreatment favored the phenols and sugars production. Additionally, about 3.21–7.50area% hydrocarbons and the reduced concentration of organic acids were obtained from pyrolysis of torrefied biomass. Torrefaction also altered the compositions of syngas by reducing CO2 and increasing H2 and CH4. The syngas was rich in H2, CH4, and CO implying that the syngas quality was significantly improved by torrefaction process. [Copyright &y& Elsevier]

Pyrolysis of torrefied Acacia nilotica was investigated in a tubular fixed-bed reactor under nitrogen environment. The process was optimized using response surface methodology coupled with central composite design, in order to obtain the maximum yield of pyrolysis oil. The maximum yield of pyrolysis oil (33.59 wt %) was obtained at 507.04 °C , retention time of 58.25 min, heating rate of 38.00 °C /min, and sweeping gas flow rate of 40.52 mL/min. Analysis of variance confirmed that pyrolysis of torrefied biomass for maximum pyrolysis oil yield highly depended on temperature followed by heating rate, retention time, and sweeping gas flow rate, respectively. Pyrolysis of raw biomass was also carried out at the optimum condition for comparing the quality of both pyrolysis oils. The pyrolysis oil samples were subjected to FTIR, GC-MS, and 13C NMR analyses along with estimation of water content, pH, viscosity, HHV, etc., for comparing the physicochemical characteristics. Results showed that total aromatic carbon, carbonyl carbon, and primary alkyl carbon of pyrolysis oil from torrefied biomass increased by 40.28, 51.36, and 6.34%, respectively, as compared to pyrolysis oil from raw biomass. The phenol derivative compounds are increased by 18.91%. The HHV and pH of pyrolysis oil from torrefied biomass increased by 23.53, 42.15%, respectively, while water content decreased by 34.37% as compared to pyrolysis oil from raw biomass. Thus, with rapid advancement in pyrolysis process, the integrated approach of torrefaction-pyrolysis process may be beneficial to produce cleaner pyrolysis oil as compare to raw biomass. Image 1 • Process variables for pyrolysis of torrefied biomass were optimized using RSM. • Torrefaction as pretreatment before pyrolysis can improve quality of pyrolysis oil. • Temperature had most significant effect on yield of pyrolysis oil. • Sweeping gas flow rate had least significant effect on yield of pyrolysis oil. • Cross-linking and devolatilization of biomass causes lower pyrolysis oil yield. [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. [ABSTRACT FROM AUTHOR]