In this paper, the most important methods of thermal conversion of biomass, such as: hydrothermal carbonization (180–250 °C), torrefaction (200–300 °C), slow pyrolysis (carbonization) (300–450 °C), fast pyrolysis (500–800 °C), gasification (800–1000 °C), supercritical steam gasification, high temperature steam gasification (>1000 °C) and combustion, were gathered, compared and ranked according to increasing temperature. A comprehensive model of thermal conversion as a function of temperature, pressure and heating rate of biomass has been provided. For the most important, basic process, which is pyrolysis, five mechanisms of thermal decomposition kinetics of its components (lignin, cellulose, hemicellulose) were presented. The most important apparatuses and implementing devices have been provided for all biomass conversion methods excluding combustion. The process of combustion, which is energy recycling, was omitted in this review of biomass thermal conversion methods for two reasons. Firstly, the range of knowledge on combustion is too extensive and there is not enough space in this study to fully discuss it. Secondly, the authors believe that combustion is not an environmentally-friendly method of waste biomass utilization, and, in the case of valuable biomass, it is downright harmful. Chemical compounds contained in biomass, such as biochar, oils and gases, should be recovered and reused instead of being simply burnt—this way, non-renewable fuel consumption can be reduced.
Waste biomass can be used as an alternative source of energy. However, such use requires prior treatment of the material. This paper describes the physicochemical characteristics of biochar obtained by the thermochemical decomposition of six types of agricultural waste biomass: residues from the production of flavored spirits (a pulp of lime, grapefruit and lemon), beetroot pulp, apple pomace, brewer’s spent grain, bark and municipal solid waste (bark, sawdust, off-cuts and wood chips). The biomass conversion process was studied under conditions of limited oxygen access in a reactor. The temperature was raised from 450 to 850 °C over 30 min, followed by a residence time of 60 min. The solid products were characterized in terms of their elemental compositions, mass, energy yield and ash content. The gaseous products from pyrolysis of the biomass were also analyzed and their compositions were characterized by GCMS (Gas Chromatography–Mass Spectrometry). The carbonization process increased the carbon content by, on average, 1.7 times, from an average percentage of 46.09% ± 3.65% for biomass to an average percentage of 74.72% ± 5.36% for biochars. After carbonization, the biochars were found to have a net calorific value of between 27 and 32 MJ/kg, which is comparable or even higher than good-quality coal (eco pea coal 24–26 MJ/kg). The net calorific values show that the volatile products can also be considered as a valuable source of energy.
This review deals with the technologies of limonene production from waste tyre pyrolysis. Thermal decomposition is attractive for tackling the waste tyre disposal problem, as it enables both: energy to be recovered and limonene to be obtained. This material management recycling of tyres is environmentally more beneficial than the burning of all valuable products, including limonene. Given this recoverability of materials from waste tyres, a comprehensive evaluation was carried out to show the main effect of process conditions (heating rate, temperature, pressure, carrier gas flow rate, and type of volatile residence and process times) for different pyrolytic methods and types of apparatus on the yield of limonene. All the results cited are given in the context of the pyrolysis method and the type of reactor, as well as the experimental conditions in order to avoid contradictions between different researchers. It is shown that secondary and side reactions are very sensitive to interaction with the above-mentioned variables. The yields of all pyrolytic products are also given, as background for limonene, the main product reported in this study.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.