Determination of the Kinetics and Thermodynamic Parameters of Lignocellulosic Biomass Subjected to the Torrefaction Process (original) (raw)
Related papers
Qualitative and kinetic analysis of torrefaction of lignocellulosic biomass using DSC-TGA-FTIR
AIMS Energy, 2015
Torrefaction is a thermochemical conversion technique to improve the fuel properties of lignocellulosic biomass by treating at temperature 200 °C-300 °C in the minimum oxygen environment for a reasonable residence time. In this study, thermal decomposition and thermal activities of miscanthus and wheat straw during the torrefaction at 200 °C , 275 °C , and 300 °C in a nitrogen environment for 45 minutes of residence time are analyzed in a simultaneous thermogravimetric analyzer (micro TGA) with a differential scanning calorimetry (DSC), and a macro-TGA. The output of the micro TGA is fed into the Fourier transform infrared spectrometry (FTIR) and qualitative analysis of the gaseous product is carried out. The composition of different gas products during the torrefaction of biomass are compared critically and kinetics were analyzed. It is found that the weight loss due to degradation of initial biomass in second stage (torrefaction process) is a much faster conversion process than the weight loss process in the first stage (drying process). The weight loss of biomass increases with increase in the residence time and torrefaction treatment temperatures. The yield after torrefaction is a solid bio-coal product. The torrefied product were less reactive and has nearly 25% better heating value than the raw biomass. Between the two feedstocks studied, torrefied miscanthus proved to be a more stable fuel than the torrefied wheat straw. The major gaseous components observed during torrefaction are water, carbon dioxide, carbon monoxide, 1,2-Dibromethylene.
Applied Sciences
In this study, three locally available biomasses, namely miscanthus, hops, sewage sludge, and additionally, their mixtures, were subjected to the torrefaction process to improve their fuel properties. The torrefaction process was conducted at 250–350 °C and 10–60 min in a nitrogen (N2) environment. The torrefaction temperature and time were studied to evaluate the selected biomass materials; furthermore, heating values, mass and energy yields, enhancement factors, torrefaction severity indexes (TSI), and energy-mass co-benefit indexes (EMCI) were calculated. In addition, thermogravimetric (TGA) and Fourier transform infrared analyses (FTIR) were performed to characterize raw and torrefied biomass under the most stringent conditions (350 °C and 60 min). The results showed that with increasing torrefaction temperature and duration, mass and energy yields decreased, and heating values (HHVs) increased for all studied biomasses. The results of the TSI and EMCI indexes showed that the op...
Transformation of lignocellulosic biomass during torrefaction
Journal of Analytical and Applied Pyrolysis, 2013
In this study, the effect of torrefaction on the chemical and structural transformation of lignocellulosic biomass was investigated using complementary analytical tools. It was observed that the acid-insoluble fraction was increased from approximately 30 to 38% and the methoxyl content was decreased to about half after torrefaction at 330 • C for 2.5 min. These results highlight the formation of condensed structures along with lignin transformation via demethoxylation. Solid-state NMR spectroscopy indicated that upon torrefaction the aromaticity increased from about 36 to 60%. For the sample torrefied at 330 • C, the nonprotonated aromatic carbon fraction was found to be about 60% of total aromatic carbons, indicating the formation of large aromatic clusters. The complementary analyses used in this study are proposed as a suitable approach for the elucidation of chemical and structural transformation of biomass during thermal treatment.
Renewable Energy, 2019
Torrefaction is a developing thermal process that has mainly been used to convert lignocellulosic feedstocks, both cultured and wasted, into a "charred" product that can be used as a fuel for power plants, combustion units, and gasifiers. Beneficial characteristics of torrefied products are increased energy density, removal of free water from the feedstock so that water is not being transported to the use facility, grindability indices similar to coal, and a more bio-stable product better suited for outdoor piled storage over the raw input material. A thorough review of the literature involving the torrefaction of fibrous agricultural wastes, food wastes, and nonlignocellulosic wastes (bacteria, algae, yeast, etc.) is presented in this paper. In general, average torrefaction operating conditions yielded greatly improved biofuels over the raw input feedstocks.
International Journal of Energy Research, 2018
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.
An investigation of raw and torrefied lignocellulosic biomasses with CaO during combustion
Journal of the Energy Institute, 2017
The thermal degradation of three categories of raw and torrefied biomass [agri-residue: wheat straw, forest residue: sawdust, energy crop: miscanthus] was studied in a TGA-FTIR system with or without catalyst (CaO). The thermal degradation of biomass was carried out in the temperature range of 25 e900 C at a heating rate of 20 C/min. The air flow rate was controlled based on the stoichiometric air requirement for complete combustion. The non-linear regression (NLREG) model was adopted to determine the kinetic parameters. The weight loss, heat flow, maximum weight loss temperature, and activation energy were observed to be dependent on the types of biomass and the process parameters. The maximum weight loss temperature was higher for torrefied biomass compared with raw biomass. The activation energy was higher in the case of torrefied biomass compared with raw biomass, and CaO helped to shrink the activation energy. The maximum weight loss temperature and activation energy were varied from 310 to 509 C and 15e85 kJ/mol, respectively. The CaO supplement seems to have a positive impact on the thermal degradation process; thus, it may help in improving the thermal degradation process of torrefied biomass.
Mass and Energy Balances of Wet Torrefaction of Lignocellulosic Biomass †
Energy & Fuels, 2010
Solid handling of diverse lignocellulosic biomass feedstock is very challenging for thermochemical conversion to renewable fuels. Wet torrefaction is a pretreatment process to convert biomass to energydense solid fuel, with relatively uniform handling characteristics. The fuel value of the produced solid may be as much as 36% higher than that of the original biomass. In the process, biomass is reacted with hot compressed water at the temperature of 200-260°C. The mass and energy balance in wet torrefaction were established for these conditions. Products include pretreated solid, precipitates (simple sugars and sugar derivatives), volatile acids, and gases (carbon dioxide). With increasing temperature, the mass of the solid decreases, the fuel value of the solid increases, and the quantity of gas increases. The heat of reaction for each temperature was estimated from an energy balance. The uncertainty analysis also showed that the temperature slightly affected the heat of reaction, which is very close to zero.
Lignocellulosic Biomass Solid Fuel Properties Enhancement via Torrefaction
Procedia Engineering, 2016
Torrefaction, also known as mild pyrolysis, is often carried out between temperature ranges of 200 and 300 o C in anoxic conditions. It is a type of thermo-chemical pre-treatment process applicable to biomass in order to convert it into compatible energy fuels. Torrefaction has favorable effects on biomass, which includes increasing its energy density and eliminating problems commonly associated with raw biomass such as high moisture content, hygroscopic behavior and low calorific value. In this study, torrefaction of agricultural residue, oil palm frond (non-woody biomass) and short rotation energy crop, Leucaena Leucocephala (woody biomass) were conducted in a horizontal tube furnace at five temperatures and holding time of 60 min. High heating values, elemental and proximate analyses results, thermal degradation profiles of torrefied fibrous products were compared to its raw forms. It was concluded that as torrefaction conditions became more severe, this led to a more qualified and energy-dense solid fuel with higher fixed carbon content, increased calorific values and reduced hydrogen and oxygen contents. The results gained from this study may provide basic information for torrefied products application in combustor and/or gasifier design.
Energies
The main objective of this review is to present the latest research results regarding the importance of the torrefaction process for different biomass materials in the last 12-year period. Despite the fact that the potential of renewable energy sources has been analyzed, research regarding that of energy derived from waste biomass still remains in the infancy state. Torrefaction is known to be one of the most effective methods for enhancing the energy efficiency of biomass. Among different types of torrefactions, the focus in this study is mostly on dry torrefaction. The influential factors, like temperature and residence time, and physico-chemical properties of torrefied products, and the prospective of torrefaction due to its reduced impact on environment, are discussed in-depth. This review provides valuable insights into the torrefaction process, which is conducive to upgrading biomass for achieving net zero carbon emissions, as it has been stated in several works that torrefied...
Physicochemical Properties of Thermally Treated Biomass and Energy Requirement for Torrefaction
Transactions of the ASABE, 2013
Torrefaction is a thermal pretreatment of biomass to overcome some of the limitations of raw biomass (e.g., low heating value and hygroscopy) for power and fuel production. The objective of this study was to examine the effects of torrefaction temperature (225°C, 250°C, and 275°C), time (15, 30, and 45 min), and their interaction on the physicchemical properties of pine, sweetgum, and switchgrass. Increasing temperature and time resulted in a decrease of solids retained while increasing the heating value of the fuel for all feedstocks. In addition, absorbed moisture decreased with torrefaction. Carbon content in biomass increased while oxygen content decreased with increasing temperature and time. Elemental composition and energy content of the torrefied biomass prepared under the most severe conditions were similar to that of coal. Furthermore, the torrefaction energy requirement at different moisture contents was successfully modeled using a simple linear regression.