Special Issue "Thermochemical Conversion of Biomass and Waste"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "Bio-Energy".

Deadline for manuscript submissions: closed (31 August 2020).

Special Issue Editors

Prof. Kentaro Umeki
E-Mail Website
Guest Editor
Luleå University of Technology, Division of Energy Science, Sweden
Interests: biomass gasification; pyrolysis; combustion; modelling and simulation
Dr. Matthias Kuba
E-Mail Website
Guest Editor
Bioenergy2020+, Unit Fluidized Bed Technology, Austria
Interests: fluidized bed gasification; waste valorization; conversion of biomass; ash transformation

Special Issue Information

Dear Colleagues,

Compared to other renewable sources, biomass and waste are unique because of their abilities to directly supply various high-value products such as liquid fuels, chemicals, and solid materials. Furthermore, biomass currently represents the majority of renewable energy sources by supplying heat and power to a large population both in developing and developed countries. Among available technologies, thermochemical conversion, e.g., combustion, gasification, pyrolysis, and hydrothermal treatment, is one of the most versatile with respect to the flexibility toward both feedstock and product. Meanwhile, waste conversion is becoming a key topic of research due to the possible economic benefit regarding the availability and often negative costs of the feedstock. However, due to the increased heterogeneity of waste compared to conventional biomass, the technical realization of such processes becomes more challenging regarding gas cleaning and upgrading to valuable end products.

Therefore, in this Special Issue, we seek your contributions on original papers and reviews about the latest research and technical development in thermochemical conversion processes. Original work on experimental investigations into detailed aspects of the processes as well as modeling and simulations is encouraged. We also encourage the technoeconomic assessment of both retrofit and innovative energy systems using thermochemical conversion technologies as it is essential to bring R&D activities into commercialization.

Prof. Kentaro Umeki
Dr. Matthias Kuba
Guest Editors

Manuscript Submission Information

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Keywords

  • biomass gasification
  • pyrolysis
  • syngas
  • biochar
  • bio-oil
  • fuel flexibility
  • poly-generation

Published Papers (17 papers)

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Research

Open AccessArticle
Thermodynamic Analysis of Iron Ore Sintering Process Based on Biomass Carbon
Energies 2020, 13(22), 5988; https://doi.org/10.3390/en13225988 - 16 Nov 2020
Viewed by 391
Abstract
The sinter process of iron ore with biomass carbon instead of coke breeze as fuel was investigated via thermodynamic analysis in this paper through a comparison of sinter composition indexes, metallurgical properties, and pollutant emissions. Straw charcoal was used in this paper, and [...] Read more.
The sinter process of iron ore with biomass carbon instead of coke breeze as fuel was investigated via thermodynamic analysis in this paper through a comparison of sinter composition indexes, metallurgical properties, and pollutant emissions. Straw charcoal was used in this paper, and its replacement does not adversely affect the composition index of iron ore, namely Fe, FeO, basicity, S, nor the metallurgical properties, namely reduction degradation index and reduction index. However, the replacement has a great effect on the emissions of pollutant gases, including SO2, NOx, CO, and CO2. The thermodynamic analysis result shows that emissions of pollutant gases produced in the sinter process significantly decrease by using straw charcoal instead of coke breeze in sinter. The sintering maximum temperature has a great influence on sintering technical indicators. The best sintering maximum temperature is between 1300 and 1400 °C, where sinter ore with high quality can be obtained. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Lumped Kinetics for Homogeneous Reactions of n-Hexadecane and n-Decene as Model Compounds for PE Pyrolysis Primary Tars
Energies 2020, 13(20), 5466; https://doi.org/10.3390/en13205466 - 19 Oct 2020
Viewed by 425
Abstract
The focus of this paper is to establish a lumped kinetic scheme for secondary reactions of tar produced from pyrolysis of plastics or polymer-based wastes. Notably, the focus is not on the detailed yield of all reaction intermediates and products but on the [...] Read more.
The focus of this paper is to establish a lumped kinetic scheme for secondary reactions of tar produced from pyrolysis of plastics or polymer-based wastes. Notably, the focus is not on the detailed yield of all reaction intermediates and products but on the propensity to form soot. Based on the assumption that that primary tar from pyrolysis of plastic wastes is mostly formed by aliphatics which can undergo progressive aromatization to polycyclic aromatic hydrocarbons (PAHs) and soot, a reaction network with 198 species and 6307 reactions proposed by Ranzi and coworkers was lumped into a very simple five reaction mechanism. The lumped kinetic model has been used to predict PAHs and soot formation in different conditions and proved to be a good alternative to comprehensive kinetic models up for relatively low temperature and short residence times (of up to 1 min at 1200 K, up to 1 s at 1400 K). At higher temperature/longer residence times, the simplified model still provides reasonable qualitative trends but the amount of PAHs and soot is underestimated. The timescale of aromatization under inert conditions appears similar for all the alkanes and alkenes examined and also the yields in main reaction products seem to scale well with the number of carbon and hydrogen atoms of the parent alkane/alkene. Evolution of the young aliphatic tar into large aromatics is prevented as long as gaseous oxygen being available for oxidation. The lumped kinetic model has been used to highlight the effect of different modes of oxygen feeding and of incomplete mixing of fuel and oxygen on the formation of PAH and soot. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
The Feasibility of Replacing Coal with Biomass in Iron-Ore Pelletizing Plants with Respect to Melt-Induced Slagging
Energies 2020, 13(20), 5386; https://doi.org/10.3390/en13205386 - 16 Oct 2020
Cited by 1 | Viewed by 502
Abstract
Combustion-generated fly ash particles in combination with the particles arising from the disintegration of iron-ore pellets, could give rise to the build-up of deposits on the refractory linings of the induration facility. Due to climate change and other environmental issues, there is a [...] Read more.
Combustion-generated fly ash particles in combination with the particles arising from the disintegration of iron-ore pellets, could give rise to the build-up of deposits on the refractory linings of the induration facility. Due to climate change and other environmental issues, there is a desire to cut down on use of fossil fuels. Therefore, it is of interest to investigate the feasibility of replacing coal with less carbon-intensive alternatives such as upgraded biomass, e.g., biochar and pyrolysis bio-oil. While the combustion of biomass can be carbon-neutral, the effects of biomass ash upon slagging during the iron-ore pelletizing process in a grate-kiln setup is unknown. In the present study, the effect of the interaction between the pellet dust and biomass-ash upon melt formation and the viscosity of the resulting melt, which can collectively affect melt-induced slagging, was theoretically assessed. The slagging potential of 15 different biomass fuels, suitable for the pelletizing process, was quantified and compared with one another and a reference high-rank coal using a thermodynamically derived slagging index. The replacement of coal with biomass in the pelletizing process is a cumbersome and challenging task which requires extensive and costly field measurements. Therefore, given the wide-ranging nature of the biomasses investigated in this study, a prescreening theoretical approach, such as the one employed in the present work, could narrow down the list, facilitate the choice of fuel/s, and help reduce the costs of the subsequent experimental investigations. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Thermochemical Conversion of Biomass in the Presence of Molten Alkali-Metal Carbonates under Reducing Environments of N2 and CO2
Energies 2020, 13(20), 5395; https://doi.org/10.3390/en13205395 - 15 Oct 2020
Viewed by 560
Abstract
The impact of N2 and CO2 atmospheres on the interaction between Eucalyptus pilularis biomass and a ternary molten carbonate eutectic (Li2CO3: Na2CO3: K2CO3) has been investigated at 600 °C [...] Read more.
The impact of N2 and CO2 atmospheres on the interaction between Eucalyptus pilularis biomass and a ternary molten carbonate eutectic (Li2CO3: Na2CO3: K2CO3) has been investigated at 600 °C and 900 °C. For lower temperature conversion under CO2, prevention of volatile release in the eutectic treated biomass is slightly higher than under N2 injection; however, similar bubble-shaped morphology of the remnant char is observed under both carrier gases. By increasing the temperature to 900 °C under CO2, the reverse Boudouard reaction begins to consume carbon fuel, while molten carbonate gasification also accelerates the reaction to a lower temperature set point (shifted from ~735 °C to ~640 °C). The mass loss of carbonate under CO2 and N2 at 900 °C is 0 (negligible) and 18 wt.%, respectively. In the absence of carbon particles, the decomposition of carbonate to M2O (l) and CO2 (g), as well as molten salt vaporization, are the sole potential routes of weight loss in an inert gas. Previous observations of biomass and eutectic mixture thermochemical conversion under N2 have suggested carbon/carbonate gasification is dominant at elevated temperatures, with production of CO expected. However, analysis of gas chromatography (GC) suggests that carbon/carbonate gasification is the weaker pathway by producing only 7 vol.% of CO, compared with molten carbonate decomposition with 27 vol.% CO2 emission for this system. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
CFD-DEM Simulation of Biomass Pyrolysis in Fluidized-Bed Reactor with a Multistep Kinetic Scheme
Energies 2020, 13(20), 5358; https://doi.org/10.3390/en13205358 - 14 Oct 2020
Viewed by 441
Abstract
The pyrolysis of biomass in a fluidized-bed reactor is studied by a combination of a CFD-DEM algorithm and a multistep kinetic scheme, where fluid dynamics, heat and mass transfer, particle collisions, and the detailed thermochemical conversion of biomass are all resolved. The integrated [...] Read more.
The pyrolysis of biomass in a fluidized-bed reactor is studied by a combination of a CFD-DEM algorithm and a multistep kinetic scheme, where fluid dynamics, heat and mass transfer, particle collisions, and the detailed thermochemical conversion of biomass are all resolved. The integrated method is validated by experimental results available in literature and a considerable improvement in predicting the pyrolysis product yields is obtained as compared to previous works using a two-fluid model, especially the relative error in the predicted tar yield is reduced by more than 50%. Furthermore, the evolution of light gas, char and tar, as well as the particle conversion, which cannot easily be measured in experiments, are also revealed. Based on the proposed model, the influences of pyrolysis temperature and biomass particle size on the pyrolysis behavior in a fluidized-bed reactor are comprehensively studied. Numerical results show that the new algorithm clearly captures the dependence of char yield on pyrolysis temperature and the influence of heating rate on light gas and tar yields, which is not possible in simulations based on a simplified global pyrolysis model. It is found that, as the temperature rises from 500 to 700 °C, the light gas yield increases from 17% to 25% and char yield decreases from 22% to 14%. In addition, within the tested range of particle sizes (<1 mm), the impact on pyrolysis products from particle size is relatively small compared with that of the operating temperature. The simulations demonstrate the ability of a combined Lagrangian description of biomass particles and a multistep kinetic scheme to improve the prediction accuracy of fluidized-bed pyrolysis. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Solar-hybrid Thermochemical Gasification of Wood Particles and Solid Recovered Fuel in a Continuously-Fed Prototype Reactor
Energies 2020, 13(19), 5217; https://doi.org/10.3390/en13195217 - 07 Oct 2020
Cited by 2 | Viewed by 466
Abstract
Solar thermochemical gasification is a promising solution for the clean production of low-emission synthetic fuels. It offers the possibility to upgrade various biomasses and waste feedstocks and further provides an efficient way to sustainably store solar energy into high-value and energy-intensive chemical fuels. [...] Read more.
Solar thermochemical gasification is a promising solution for the clean production of low-emission synthetic fuels. It offers the possibility to upgrade various biomasses and waste feedstocks and further provides an efficient way to sustainably store solar energy into high-value and energy-intensive chemical fuels. In this work, a novel continuously-fed solar steam gasifier was studied using beechwood and solid recovered fuels (SRF) particles. Solar-only and hybrid solar/autothermal gasification experiments were performed at high temperatures to assess the performance of the reactor and its flexibility in converting various types of feedstocks. The hybrid operation was considered to increase the solar reactor temperature when the solar power input is not sufficient thanks to partial feedstock oxy-combustion. The hybrid solar process is thus a sustainable alternative option outperforming the conventional gasification processes for syngas production. Wood and waste particles solar conversion was successfully achieved, yielding high-quality syngas and suitable reactor performance, with Cold Gas Efficiencies (CGE) up to 1.04 and 1.13 respectively during the allothermal operation. The hybrid process allowed operating with a lower solar power input, but the H2 and CO yields noticeably declined. SRF gasification experiments suffered furthermore from ash melting/agglomeration issues and injection instabilities that undermined the continuity of the process. This study demonstrated the solar reactor flexibility in converting both biomass and waste feedstocks into syngas performed in continuous feeding operation. The experimental outcomes showed the feasibility of operating the reactor in both allothermal (solar-only) and hybrid allothermal/autothermal (combined solar and oxy-combustion heating) for continuous syngas production with high yields and energy conversion efficiencies. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Effects of Porous Structure Development and Ash on the Steam Gasification Reactivity of Biochar Residues from a Commercial Gasifier at Different Temperatures
Energies 2020, 13(19), 5004; https://doi.org/10.3390/en13195004 - 23 Sep 2020
Viewed by 503
Abstract
The present study aims at investigating the effects of porous structure development and ash content on the observed reactivity during steam gasification of biochar residues from a commercial gasifier. The experiments were conducted at a temperature range of 700 to 800 °C using [...] Read more.
The present study aims at investigating the effects of porous structure development and ash content on the observed reactivity during steam gasification of biochar residues from a commercial gasifier. The experiments were conducted at a temperature range of 700 to 800 °C using biochar, derived from entrained flow gasification of biomass, under isothermal conditions using a thermogravimetric analyzer. The pore size distribution, surface area and morphology of char samples were determined by N2 physiosorption and scanning electron microscopy (SEM). The results showed that the gasification temperature does not affect the porous structure development considerably. The total surface area of char exhibits a threefold increase, while the total pore volume increase ranges between 2.0 and 5.3 times, at all temperatures. Both properties are directly proportional to the observed reactivity, especially at conversions up to 70%. Catalytic effects of the mineral matter of the char (mainly potassium) become predominant at the later stages of conversion (conversion greater than 70%). Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Fast Pyrolysis of Lignin Pretreated with Magnesium Formate and Magnesium Hydroxide
Energies 2020, 13(19), 4995; https://doi.org/10.3390/en13194995 - 23 Sep 2020
Viewed by 378
Abstract
Kraft lignin (Indulin AT) pretreated with magnesium formate and magnesium hydroxide was fast-pyrolyzed in a continuously fed, bench-scale system. To avoid fouling issues typically associated with lignin pyrolysis, a simple laboratory test was used to determine suitable ranges of magnesium hydroxide and formic [...] Read more.
Kraft lignin (Indulin AT) pretreated with magnesium formate and magnesium hydroxide was fast-pyrolyzed in a continuously fed, bench-scale system. To avoid fouling issues typically associated with lignin pyrolysis, a simple laboratory test was used to determine suitable ranges of magnesium hydroxide and formic acid to lignin for feeding without plugging problems. Various feedstock formulations of lignin pretreated with magnesium hydroxide and formic acid were pyrolyzed. For comparison, calcium formate pretreated lignin was also tested. The organic oil yield ranged from 9% to 17% wt % on a lignin basis. Carbon yields in the oil ranged from 10% to 18% wt % on a lignin basis. Magnesium formate pretreatment increased oil yield and carbon yield in the oil up to 35% relative to the higher 1:1 g magnesium hydroxide/g lignin pretreatment. However, a lower magnesium hydroxide pretreatment (0.5:1 g magnesium hydroxide/g lignin) resulted in oil yields and carbon yields in the oils similar to the magnesium formate pretreatments. Magnesium formate pretreatment produced more oil but with a higher oxygen content than calcium formate under the same conditions. The GC-MS analysis of product oils indicated that phenols and aromatics were more prevalent in pyrolyzed magnesium-formate-pretreated lignin. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Gasification of Cup Plant (Silphium perfoliatum L.) Biomass–Energy Recovery and Environmental Impacts
Energies 2020, 13(18), 4960; https://doi.org/10.3390/en13184960 - 22 Sep 2020
Cited by 1 | Viewed by 432
Abstract
Biomass from cup plant (Silphium perfoliatum L.) is considered a renewable energy source that can be converted into alternative fuel. Calorific syngas, a promising type of advanced fuel, can be produced through thermochemical biomass gasification. In this study, the suitability of cup [...] Read more.
Biomass from cup plant (Silphium perfoliatum L.) is considered a renewable energy source that can be converted into alternative fuel. Calorific syngas, a promising type of advanced fuel, can be produced through thermochemical biomass gasification. In this study, the suitability of cup plant biomass for gasification was assessed, including the process energy balance and environmental impacts of waste from syngas purification. Silphium perfoliatum L. was cultivated as a gasification feedstock in different conditions (irrigation, fertilization). The experiments were performed in a membrane gasifier. All obtained energy parameters were compared to the biomass yield per hectare. The toxic effects of liquid waste were assessed using tests analyzing germination/seed root elongation of Sinapsis alba. Leachates collected from condensation tanks of a gas generator were introduced to soil at the following doses: 100, 1000 and 10,000 mg kg−1 DM of soil. The usefulness of Silphium perfoliatum L. for gasification was confirmed. The factors of plant cultivation affected the biomass yield, the volume and calorific value of syngas and the amount of biochar. It was determined that the components found in condensates demonstrate a phytotoxic effect, restricting or inhibiting germination and root elongation of Sinapsis alba. Due to this potential hazard, the possibility of its release to the environment should be limited. Most of the biomass is only used for heating purposes, but the syngas obtained from the cup plant can be used to power cogeneration systems, which, apart from heat, also generate electricity. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Investigation of Pulverized Biomass and Coal Char Emissivity
Energies 2020, 13(18), 4620; https://doi.org/10.3390/en13184620 - 05 Sep 2020
Viewed by 413
Abstract
Current work presents an optical setup, its calibration and reference process and the first results from single particle emissivity measurements of pulverized biomass and coal fuel particles. In contrast to earlier attempts, the setup offers the possibility of emissivity measurements during the whole [...] Read more.
Current work presents an optical setup, its calibration and reference process and the first results from single particle emissivity measurements of pulverized biomass and coal fuel particles. In contrast to earlier attempts, the setup offers the possibility of emissivity measurements during the whole particle burn-off. A laser ignites a single particle, placed in the center of the setup. Two photomultipliers observe the emitted particle radiation in the visible range (550 nm and 700 nm) for temperature calculation, using two-color pyrometry. An InSb-detector records the emitted particle radiation between 2.4 µm and 5.5 µm, which is later used to calculate particle emissivity in this range. The conclusion of multiple particle measurements lead to decreasing particle emissivity with increasing temperature. For coal particles the emissivity decreases from 0.45 at 2300 K to 0.03 at 3400 K. Biomass char shows a similar trend with a decrease from 0.18 (2100 K) to 0.03 (2900 K). Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Extraction of Nitrogen Compounds from Tobacco Waste via Thermal Treatment
Energies 2020, 13(18), 4619; https://doi.org/10.3390/en13184619 - 05 Sep 2020
Viewed by 445
Abstract
Alkaloids, typical nitrogen compounds, were found to be abundant in tobacco waste. The recovery of alkaloids from tobacco waste for biological pesticides could reduce the use of traditional chemical pesticides and avoid the pollution of farmland by the leaching of alkaloids from tobacco [...] Read more.
Alkaloids, typical nitrogen compounds, were found to be abundant in tobacco waste. The recovery of alkaloids from tobacco waste for biological pesticides could reduce the use of traditional chemical pesticides and avoid the pollution of farmland by the leaching of alkaloids from tobacco waste. Considering the fact that alkaloids can easily volatilize, thermal treatment is expected to be a potential technology to achieve the release and recovery of alkaloids from tobacco waste. For better understanding of conversion behavior of nitrogen-containing compounds in tobacco waste during thermal treatment, purge/trap-GC/MS (gas chromatography mass spectrometry), PY-GC/MS (pyrolysis-gas chromatography mass spectrometry), and fixed-bed/ATD-GC/MS (auto-thermal desorption gas chromatography mass spectrometry) were adopted to detect the ingredients and concentration of nitrogen-containing compounds in tobacco waste and/or volatiles. The results of purge/trap-GC/MS showed that nitrogen-containing compounds in tobacco waste could be effectively evaporated at 180 °C in the forms of N-benzyl-N-ethyl-P-isopropyl benzamide, 2-Amino-4-methylphenol, or N-butyl-tert-butylamine. Specifically, N-benzyl-N-ethyl-P-isopropyl benzamide was the main nitrogenous compound in the volatiles of tobacco wastes accordingly. (S)-3-(1-Methyl-2-pyrrolidinyl) pyridine was dominant in N-compounds in pyrolysis condition according to the results of Py-GC/MS. In air atmosphere, with the heating temperature increasing, the concentration of main (S)-3-(1-Methyl-2-pyrrolidinyl) pyridine was firstly increased and then decreased. Besides, the interactions between the released volatiles could be accelerated at a high temperature. Accordingly, these findings suggested that pyrolysis under proper conditions could effectively promote the extraction of alkaloids from tobacco waste. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Pyrolysis of Rapeseed Oil Press Cake and Steam Gasification of Solid Residues
Energies 2020, 13(17), 4472; https://doi.org/10.3390/en13174472 - 31 Aug 2020
Viewed by 416
Abstract
A deoiled rapeseed press cake (RPC) was pyrolyzed by heating at a slow heating rate to 1000 °C in a fixed bed reactor, and the produced char was then gasified to obtain data for the kinetic modeling of the process. The gasification experiments [...] Read more.
A deoiled rapeseed press cake (RPC) was pyrolyzed by heating at a slow heating rate to 1000 °C in a fixed bed reactor, and the produced char was then gasified to obtain data for the kinetic modeling of the process. The gasification experiments were performed in a thermogravimetric analyzer (TGA) under steam/argon mixtures at different temperatures (750, 800 and 850 °C) and steam mole fractions (0.17 and 0.45). The three most commonly used gas-solid kinetic models, the random pore model, the volumetric model and the shrinking core model were used to describe the conversion of char during steam gasification. The objective of the kinetic study was to determine the kinetic parameters and to assess the ability of the models to predict the RPC conversion during steam gasification. A TGA-MS analysis was applied to assess the composition of the product gas. The main steam gasification product of the RPC was hydrogen (approximately 60 mol % of the total product). The volumetric model was able to accurately predict the behavior of the RPC char gasification with steam at temperatures of 750–850 °C and steam concentrations less than 0.45 mole fraction. The activation energy and the reaction order with respect to steam were equal to 166 kJ/mol and 0.5, respectively, and were typical values for the gasification of biomass chars with steam Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Conversion of Biogas to Renewable Energy by Microwave Reforming
Energies 2020, 13(16), 4093; https://doi.org/10.3390/en13164093 - 07 Aug 2020
Cited by 1 | Viewed by 554
Abstract
Biogas consists of methane and carbon dioxide, the main components, which are major greenhouse gases that affect global warming. As such, in order to convert greenhouse gas into renewable energy, which is a high-quality fuel, the biogas microwave reforming characteristics were studied and [...] Read more.
Biogas consists of methane and carbon dioxide, the main components, which are major greenhouse gases that affect global warming. As such, in order to convert greenhouse gas into renewable energy, which is a high-quality fuel, the biogas microwave reforming characteristics were studied and the results are as follows: In the main components of biogas, methane and carbon dioxide, the conversion efficiency of both methane and carbon dioxide increased as the amount of CO2 relatively increased. This is because the problem of active pore failure due to gasification of the attached carbon generated during methane reforming was overcome. When nitrogen, a biogas-containing component, was added, the activity of catalytic activity pores was enhanced by promoting the production of microplasma, resulting in increased conversion efficiency. When the concentration of oxygen, which is a biogas-containing component, increased, the conversion efficiency increased, but when the concentration is more than 10%, the fuel value of the product gas decreased due to the complete oxidation reaction. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Investigation of the Formation of Coherent Ash Residues during Fluidized Bed Gasification of Wheat Straw Lignin
Energies 2020, 13(15), 3935; https://doi.org/10.3390/en13153935 - 01 Aug 2020
Cited by 1 | Viewed by 664
Abstract
Thermal conversion of ash-rich fuels in fluidized bed systems is often associated with extensive operation problems caused by the high amount of reactive inorganics. This paper investigates the behavior of wheat straw lignin—a potential renewable fuel for dual fluidized bed gasification. The formation [...] Read more.
Thermal conversion of ash-rich fuels in fluidized bed systems is often associated with extensive operation problems caused by the high amount of reactive inorganics. This paper investigates the behavior of wheat straw lignin—a potential renewable fuel for dual fluidized bed gasification. The formation of coherent ash residues and its impact on the operation performance has been investigated and was supported by thermochemical equilibrium calculations in FactSage 7.3. The formation of those ash residues, and their subsequent accumulation on the surface of the fluidized bed, causes temperature and pressure fluctuations, which negatively influence the steady-state operation of the fluidized bed process. This paper presents a detailed characterization of the coherent ash residues, which consists mostly of silica and partially molten alkali silicates. Furthermore, the paper gives insights into the formation of these ash residues, dependent on the fuel pretreatment (pelletizing) of the wheat straw lignin, which increases their stability compared to the utilization of non-pelletized fuel. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Fluidised Bed Gasification of Diverse Biomass Feedstocks and Blends—An Overall Performance Study
Energies 2020, 13(14), 3706; https://doi.org/10.3390/en13143706 - 18 Jul 2020
Cited by 1 | Viewed by 476
Abstract
The aim of this work is to investigate the fluidised bed gasification of several pure and blended feedstock prepared in the form of pellets: oak bark, two bark/wheat straw blends (85/15 and 50/50 wt%) and lignin residue remaining from bioethanol production. Gasification conditions [...] Read more.
The aim of this work is to investigate the fluidised bed gasification of several pure and blended feedstock prepared in the form of pellets: oak bark, two bark/wheat straw blends (85/15 and 50/50 wt%) and lignin residue remaining from bioethanol production. Gasification conditions were defined to be representative of dual fluidised bed ones (steam gasification at 850 °C, followed by air combustion of the char). The cold gas efficiency (77–81%), gas composition and tar content (0.9–2.3 g/kgdaf) are close for the gasification of bark and the two bark/wheat straw blends. For lignin residue, the cold gas efficiency is lower (71%), and the tar content is 9.1 g/kgdaf. The agglomeration propensity is much higher for lignin residue than for the other feedstock. This was put into evidence with in-bed temperature measurements at different levels, and confirmed with post-test size screening of the bed material particles. The 50/50 wt% bark/wheat straw blend seems to undergo defluidisation in combustion, however followed by refluidisation of the bed. These findings were also well correlated with a predictive model for defluidisation. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Unraveling the Properties of Biomass-Derived Hard Carbons upon Thermal Treatment for a Practical Application in Na-Ion Batteries
Energies 2020, 13(14), 3513; https://doi.org/10.3390/en13143513 - 08 Jul 2020
Cited by 1 | Viewed by 635
Abstract
Biomass is gaining increased attention as a sustainable and low-cost hard carbon (HC) precursor. However, biomass properties are often unexplored and unrelated to HC performance. Herein, we used pine, beechwood, miscanthus, and wheat straw precursors to synthesize HCs at 1000 °C, 1200 °C [...] Read more.
Biomass is gaining increased attention as a sustainable and low-cost hard carbon (HC) precursor. However, biomass properties are often unexplored and unrelated to HC performance. Herein, we used pine, beechwood, miscanthus, and wheat straw precursors to synthesize HCs at 1000 °C, 1200 °C and 1400 °C by a two-steps pyrolysis treatment. The final physicochemical and electrochemical properties of the HC evidenced dissimilar trends, mainly influenced by the precursor’s inorganic content, and less by the thermal treatment. Pine and beechwood HCs delivered the highest reversible capacity and coulombic efficiency (CE) at 1400 °C of about 300 mAh·g−1 and 80%, respectively. This performance can be attributed to the structure derived from the high carbon purity precursors. Miscanthus and wheat straw HC performance was strongly affected by the silicon, potassium, and calcium content in the biomasses, which promoted simultaneous detrimental phenomena of intrinsic activation, formation of a silicon carbide phase, and growth of graphitic domains with temperature. The latter HCs delivered 240–200 mAh·g−1 of reversible capacity and 70–60% of CE, respectively, at 1400 °C. The biomass precursor composition, especially its inorganic fraction, seems to be a key parameter to control, for obtaining high performance hard carbon electrodes by direct pyrolysis process. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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Open AccessArticle
Co-Pyrolysis of Beet Pulp and Defecation Lime in TG-MS System
Energies 2020, 13(9), 2304; https://doi.org/10.3390/en13092304 - 06 May 2020
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Abstract
The process of pyrolysis of beet pulp, a by-product after the extraction of raw sugar from sugar beet, with the addition of defecation lime was studied in a thermobalance coupled with a mass spectrometer. The beet pulp pyrolysis process took place completely at [...] Read more.
The process of pyrolysis of beet pulp, a by-product after the extraction of raw sugar from sugar beet, with the addition of defecation lime was studied in a thermobalance coupled with a mass spectrometer. The beet pulp pyrolysis process took place completely at 600 °C, and the resulting char, tar and gas were characterized by higher heating values of 23.9, 21.6 and 7.77 MJ/kg, respectively. The addition of the defecation lime to beet pulp caused both an increase in the char production yield and a decrease in the tar production yield. At the same time, the higher heating value of char and tar decreased along with the increase of defecation lime added to the sample. The deconvolution of derivative thermogravimetric (DTG) curves allowed us to identify the basic components of beet pulp, for which the activation energy by isoconversion method was calculated. The 20 wt.% addition of defecation lime caused an increase of the activation energy by about 18%. Further increase in the defecation lime content resulted in a reduction of activation energy. At the temperature above 600 °C, calcination of calcium carbonate contained in defecation lime occurred. The CO2 produced during calcination process did not cause auto-gasification of char. Full article
(This article belongs to the Special Issue Thermochemical Conversion of Biomass and Waste)
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