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Biomass Energy
Published in Sergio C. Capareda, Introduction to Renewable Energy Conversions, 2019
Thermal conversion processes are biomass conversion processes that utilize high temperatures or heat to convert biomass into useful products. There are basically four types according to the amount of air introduced as well as the temperature used for the reaction. The four thermal conversion processes include (a) torrefaction, (b) pyrolysis, (c) gasification, and (d) combustion. Torrefaction and pyrolysis are reactions that use no oxygen or air, while gasification and combustion both utilize amounts of oxygen or air. Torrefaction is done at lower temperatures, usually below 300°C [572°F], while pyrolysis is done above 300°C [572°F] (Capareda, 2014). Torrefaction is simply a biomass conditioning process— it hardly produces any new product but rather enhances the quality of the biomass in the form of char. Gasification uses incomplete amounts of air (or that below stoichiometry), whereas combustion uses excess amounts of air. As such, the operating temperature for gasification systems is much lower than that of combustion systems. The three thermal conversion systems will be discussed in succeeding sections.
Introduction
Published in M.R. Riazi, David Chiaramonti, Biofuels Production and Processing Technology, 2017
Chapter 8 discusses the production of bio-based hydrocarbons and chemicals (such as alkenes and aromatics) using biomass feedstocks. The focus has been on the introduction of commercial and industrialized processes using both thermochemical and catalytic conversions, with description of process conditions, reactor design, and kinetic models. Triglycerides and fatty acids are converted to bio-derived hydrocarbons through hydrodeoxygenation and catalytic cracking/isomerization, while lignocellulosic materials are converted through fractionation, fast pyrolysis, torrefaction, or gasification (to maximize syngas) to bio-oil, biochar, or biogas (syngas). Syngas is then converted to liquid hydrocarbons through the Fischer–Tropsch process or other catalytic steps. Bio-derived hydrocarbons can then be converted into aromatics or alkenes through a steam cracking process. Torrefaction is an anaerobic thermal process that converts biomass into a kind of coal-like material (torrefied biomass) with higher energy density than the original feedstock. In this process, heating of biomass is carried out in the absence of oxygen: the weight loss is nearly 30%, while energy loss is about 10%. While torrefaction maximizes the yield of solid carbonaceous material, fast pyrolysis maximizes the yield of condensable organic molecules, and gasification maximizes the yield of noncondensable gases as explained in this chapter.
Production of Bio-Syngas for Biofuels and Chemicals
Published in Arindam Kuila, Sustainable Biofuel and Biomass, 2019
Shritoma Sengupta, Debmallya Konar, Debalina Bhattacharya, Mainak Mukhopadhyay
Torrefaction is a mild thermal treatment of biomass, at 250–300°C that efficiently turns solid biomass such as hemicellulose; one of the most reactive parts of wood which is decomposed into a brittle, easy to reduce material resembling coal (Bergman et al., 2005b; 2005c). The process takes place in oxygen-free conditions and atmospheric pressure. Torrefaction improves the physical and chemical properties of biomass as a fuel (Dudyński et al., 2015). It raises the energy density, by lowering the oxygen to carbon ratio and hydrogen to carbon ratio, and making it lesser hydrophilic (Chew and Doshi, 2011).
Multiphysics modeling of ultrasound-assisted biomass torrefaction for fuel pellets production
Published in IISE Transactions, 2023
To overcome these challenges, several biomass pre-processing methods have been proposed, these include chemical (e.g., ammonia fiber explosion), thermal (e.g., torrefaction), and mechanical (e.g., size reduction) means (Shankar Tumuluru et al.,2011). Among all the methods, torrefaction significantly alters the structural composition and physical properties of biomass. This method is a thermal treatment at a temperature range of 200–300 °C (473–573 K) that enhances the energy density of biomass and upgrades it to a high-quality fuel (Arias et al., 2008; Biswas et al.,2017). Conventional torrefaction usually requires a long reaction time (30 minutes to several hours), whereas the present work utilizes an ultrasound-assisted system to generate biomass torrefaction within tens of seconds.
Synergistic effect of additives and blend on sulfur retention, NO release and ash fusibility during combustion of biomass briquettes
Published in International Journal of Green Energy, 2021
Kuihua Han, Xian Li, Jianhui Qi, Yingquan Zhu, Shenwei Long, Haopeng Li, Shengli Niu, Shujuan Li, Yang Xu
There are various ways to upgrade biomass fuels, such as torrefaction, carbonization, pyrolysis, gasification, densifying, and molding. For sources such as crop straws, which have lower energy density than the standard coal, upgrading is necessary (Pradhan, Mahajani, and Arora 2018; Sharma and Murugan 2017, 2016, 2014; Tumuluru 2017). Torrefaction is a thermal pre-treatment process to upgrade biomass, through heating biomass at a temperature range of 200°C to 300°C in an inert atmosphere (Qi et al. 2017a). An enhancement is carbonization, which heats biomass at temperature of 300°C to 500°C in an inert atmosphere to obtain highly fragrant refractory solid matter (Qi et al. 2017a). Pyrolysis is a thermal process that heats and decomposes biomass at high temperature (300°C to 1000°C) in an inert environment to obtain pyrolysis product. Without obtaining solid product, gasification is a method to produce “product gas” at lower temperatures (below 1000°C) and “syngas” with high temperatures (above 1200°C).
Effect of process parameters on the performance of an air-blown entrained flow cyclone gasifier
Published in International Journal of Sustainable Energy, 2020
Pantea Hadi Jafari, Anders Wingren, J. Gunnar I. Hellström, B. Rikard Gebart
Type of fuel feedstock has influence on the heating value of the product gas, gasification efficiency, amount of unconverted carbon and submicron particles, as well as the composition of the product gas (Risberg et al. 2014). Different kinds of biofuels with a wide variation of properties including stem wood, peat, rice husk, bark and torrefied spruce that are available in Sweden and elsewhere have been selected to study. Torrefied biomass is a relatively new fuel of great interest in the energy sector as an alternative to fossil fuels. Torrefaction is a thermal treatment of biomass at 200–300°C to increase the energy density and enhance its physical and chemical characteristics for the gasification process (Stelt et al. 2011). Peat is another biofuel of potential interest and available at low cost which is classified in a category between fossil and renewable fuels according to the report of Intergovernmental Panel on Climate Change (IPCC) (Risberg et al. 2014). In Sweden, the bark is a considerable residue from the wood industries that can be used to supply heating plants. In Asian countries, rice husk is available in large quantities for using in CHP plants (Bergqvist et al. 2008). However, rice husk is a problematic fuel because of its low bulk density and high ash content.