Search Results (57)

The amount of waste generated by society is constantly increasing. Consequently, there is a need to develop new and better methods of treating it. A significant part of municipal waste is biowaste, which can be treated as a source of valuable resources such as nutrients, organic matter, and energy. The present work aims to determine the properties of the tested household biowaste and the possibility of using it as feedstock in slow pyrolysis to obtain biochar. The slow pyrolysis process of the biowaste was carried out in an electrically heated Horizontal Tube Furnace (HTF) at temperatures of 400 °C, 500 °C, and 600 °C in a nitrogen atmosphere. The analysis showed that depending on the type and composition of the biowaste, its properties are different. All the biowaste tested has a high moisture content (between 63.51% and 81.53%), which means that the biowaste needs to be dried before the slow pyrolysis process. The characteristics of kitchen biowaste are similar to those of food waste studied by other researchers in different regions of the world. In addition, the properties of kitchen biowaste are similar to those of the typical biomasses used to produce biochar via slow pyrolysis, such as wood, almond shells, and rice husks. Both kinds of garden biowaste tested may have been contaminated (soil, rocks) during collection, which affected the high ash content of spring (17.75%) and autumn (43.83%) biowaste. This, in turn, affected all the properties of the garden biowaste, which differed significantly from both the literature data of other garden wastes and from the properties of typical biomass feedstocks used to produce biochar in slow pyrolysis. For all biowaste tested, it was shown that as the pyrolysis temperature increases, the yield of biochar decreases. The maximum mass yield of biochar for kitchen, spring garden, and autumn garden biowaste was 36.64%, 66.53%, and 66.99%, respectively. Comparing the characteristics of biowaste before slow pyrolysis, biochar obtained from kitchen biowaste had a high carbon content, fixed carbon, and a higher HHV. In contrast, biochar obtained from garden biowaste had a lower carbon content and a lower HHV. Full article

Archeological structures connected with iron metallurgy were identified in the outskirts of the town Lučenec, Slovakia. Based on the shapes and decoration of the ceramic fragments, it was possible to date them to the 9th or 10th century. The first group of discovered metallurgical materials included slags with low wüstite content, which looks like slag from younger higher-shaft furnaces. The second group included slags which could be attributed to the technology common at the time of the site’s existence: iron smelting in lower free-standing shaft furnaces with average efficiency. The third group were slags from the forging of iron blooms to remove pores and slag particles. The fourth group consisted of ceramics fragments (tuyeres and refractory material). Bog ore was probably smelted using principally oak wood charcoal. Full article

This study explores a circular economy approach in charcoal production, utilizing combustion gases from the process itself to optimize efficiency and quality, minimizing waste and reducing emissions. The research investigates the pre-drying of Eucalyptus sp. wood with these gases before carbonization, through an innovative system that directs gases from the carbonizing furnace to a separate drying furnace. Wood samples were dried at 120 °C and 150 °C for 15, 22.5, and 30 h before carbonization. The analysis included the gravimetric yield of charcoal, semi-carbonized wood, and fines, in addition to evaluating key charcoal properties. Results demonstrated that drying with combustion gases at 150 °C increased the charcoal yield by 7%, regardless of drying time. Furthermore, this pre-drying improved charcoal quality, raising fixed carbon content from 74.68% to over 81% and reducing volatile matter from 24.40% to below 18%. These findings highlight that the utilization of combustion gases for wood drying not only significantly enhances the efficiency and quality of charcoal production but also contributes to the reduction in greenhouse gas emissions, promoting a more sustainable and environmentally friendly alternative compared to conventional methods. Full article

This work aimed to analyze the PAH content in products smoked in traditional smokehouses with direct and indirect heat sources and in an industrial way as an element of PAH content monitoring in Polish market products. This research material comprised 12 smoked meats (W) and 38 sausages (K), medium or coarsely minced. The content of benzo(a)pyrene and the total content of four marker PAHs was determined by GC-MS. The analysis showed a significantly higher level of PAH contamination in products smoked using traditional methods. The results also indicate that the natural casing is not a barrier against PAH contamination during traditional smoking, and a higher degree of meat fragmentation, together with a small cross-section, increases the PAH content in this technological group. Concentrations of benzo(a)pyrene exceeding the permissible levels were found in the sausages smoked for more than 60 min. As part of the strategies for reducing the PAH content, among others, changing the furnace to an indirect one, shortening the time, lowering the smoking temperature, using artificial casings or removing casings before consumption, drying the product surface before the smoking process, using seasoned and bark-free wood, as well as additional smokehouse equipment, are recommended. Full article

As the iron and steel industry needs to cut its CO₂ emissions drastically, much effort has been put into establishing new—less greenhouse-gas-intensive—production lines fueled by hydrogen and electricity. Blast furnaces, as a central element of hot iron production, are expected to lose importance, at least in European production strategies. Yet, blast furnaces could play a significant role in the transitional phase, as they allow for the implementation of another CO₂-reducing fuel, carbonized wood reducing agents, as a substitute for coal in auxiliary injection systems, which are currently widely used. Wood carbonization yields vastly differing fuel types depending on the severity of the treatment process, mainly its peak temperature. The goal of this study is to define the lowest treatment temperature, i.e., torrefaction temperature, which results in a biogenic reducing agent readily employable in existing coal injection systems, focusing on their conveying properties. Samples of different treatment temperatures ranging from 285 to 340 °C were produced and compared to injection coal regarding their chemical and mechanical properties. The critical conveyability in a standard dense-phase pneumatic conveying system was demonstrated with a sample of pilot-scale high-temperature torrefaction. Full article

The growing demand for eco-friendly activated carbon necessitates sustainable production methods. This study investigates the conversion of waste wood into activated carbon using goethite iron ore as an activating agent. A high-temperature rotary furnace was used to activate the carbon at 1373 K. The oxygen released from the iron oxide during the heat treatment reacted with the carbon in the wood, resulting in 49% of activated carbon with BET surface areas between 684 m²/g and 770 m²/g. The activated carbon and char showed type I isotherms with micropore areas between 600 m²/g and 668 m²/g, respectively. Additionally, 92% of the iron in the ore was reduced from ferric to ferrous. The findings demonstrate that goethite iron ore is an effective activating agent for producing wood-based activated carbon while also generating metallic iron as a byproduct. This alternative activation method enhances the sustainability and efficiency of activated carbon production. Full article

With the increasing production of municipal sewage sludge (MSS) worldwide, the development of efficient and sustainable strategies for its management is crucial. Pyrolysis of MSS offers several benefits, including volume reduction, pathogen elimination, and energy recovery through the production of biochar, syngas, and bio-oil. However, the process can be limited by the composition of the MSS, which can affect the quality of the biochar. Co-pyrolysis has emerged as a promising solution for the sustainable management of MSS, reducing the toxicity of biochar and improving its physical and chemical properties to expand its potential applications. This review discusses the status of MSS as a feedstock for biochar production. It describes the types and properties of various co-substrates grouped according to European biochar certification requirements, including those from forestry and wood processing, agriculture, food processing residues, recycling, anaerobic digestion, and other sources. In addition, the review addresses the optimization of co-pyrolysis conditions, including the type of furnace, mixing ratio of MSS and co-substrate, co-pyrolysis temperature, residence time, heating rate, type of inert gas, and flow rate. This overview shows the potential of different biomass types for the upgrading of MSS biochar and provides a basis for research into new co-substrates. This approach not only mitigates the environmental impact of MSS but also contributes to the wider goal of achieving a circular economy in MSS management. Full article

This paper includes a discussion of the results of tests concerning changes in the thermal and emission parameters of a boiler fuelled with wood biomass under the influence of air gradation in the combustion process. The test results ensure insight into the combustion process of wood biomass with air gradation, which significantly affected the operation of the device, increasing the mass concentration of the emitted nitrogen oxide (NO_x) by combustion temperature lowering, especially in the afterburning zone. The authors observed an increase in the emission of particulate matter (PM) and carbon monoxide (CO) related to the change in the combustion process stoichiometry. The tests were carried out with the use of a heating boiler equipped with an automatic pellet burner. Apart from the mass concentration measurement of the pollution emitted, the tests focused on the measurements of temperature and oxygen levels in the flue gas. The objective of the tests was to confirm the applicability of the air gradation techniques in biomass combustion in order to reduce the emission of harmful substances from heating boilers, which is a technique that has recently been used in this group of devices. The test results obtained confirm the necessity for reorganising the technical systems of the currently used pellet burners and implementing further empirical tests. Full article

Brazil is the world’s largest producer of charcoal. Therefore, there is need for improvement in the gravimetric yield of conversion and the reduction of gas emissions, including greenhouse gases (GHGs), released during carbonization. The objective was to apply the methodology of Measurement, Reporting and Verification (MRV) to evaluate the emission of GHG, mainly CO₂ and CH₄. The charcoal production kiln-furnace system used was composed of 4 kilns with a capacity of ~6 t of wood, each. The MRV cluster of coal gravimetric yield and gas burners were used to determine the gravimetric yield and burner efficiency and thus evaluate the emission of GHGs generated in the carbonization system. The carbonization was performed in an isolated way producing, in total, 3.34 t of charcoal, with an average gravimetric yield of 25.82%. The MRV methodology was effective for evaluating the GHG emissions. The wood burner reduced by 50% the methane burning and provided a reduction of 0.392 tCO₂ eq (23.91%). The humidity of wood and high precipitation were the main limiting factors in this research, and responsible for the decrease in the gravimetric yield. The kiln-furnace system was effective for a sustainable production with the use of non-continuous carbonization gas burners. Full article

In the past few years, wind power has become a viable alternative in Brazil to diversify the energy mix and mitigate pollutant emissions from fossil fuels. Significant wind energy generation potential is inherent in the Brazilian Northeast state of Rio Grande do Norte, due to prevailing strong winds along the coastline and elevated regions. However, clean and renewable wind energy may lead to potential biodiversity impacts, including the removal of native vegetation during plant construction and operation. This case study explores the flash pyrolysis-based valorization of three commonly suppressed species, namely Cenostigma pyramidale (CP), Commiphora leptophloeos (CL), and Aspidosperma pyrifolium (AP), in a wind farm situated within the Mato Grande region of Rio Grande do Norte State. The study centers on determining their bioenergy-related properties and assessing their potential for producing phenolic-rich bio-oil. The investigation of three wood residues as potential sources of high-value chemicals, specifically phenolic compounds, was conducted using a micro-furnace type temperature programmable pyrolyzer combined with gas chromatography/mass spectrometry (Py–GC/MS setup). The range of higher heating values observed for three wood residues was 17.5–18.4 MJ kg⁻¹, with the highest value attributed to AP wood residue. The bulk density ranged from 126.5 to 268.7 kg m⁻³, while ash content, volatile matter content, fixed carbon content, and lignin content were within the respective ranges of 0.8–2.9 wt.%, 78.5–89.6 wt.%, 2.6–9.5 wt.%, and 19.1–30.6 wt.%. Although the energy-related properties signifying the potential value of three wood residues as energy resources are evident, their applicability in the bioenergy sector can be expanded via pelleting or briquetting. Yields of phenolic compounds exceeding 40% from the volatile pyrolysis products of CL and AP wood residues at 500 °C make them favorable for phenolic-rich bio-oil production. The findings of this study endorse the utilization of wood residues resulting from vegetation suppression during the installation of wind energy plants as potential feedstocks for producing bioenergy and sustainable phenolic compounds. This presents a solution for addressing a regional environmental concern following the principles of green chemistry. Full article

In this research, a thermoelectric generator is used to absorb waste heat on the walls of a wood charcoal burning stove to produce electrical energy. The research was carried out using 4 Thermoelectric Generators (TEGs) attached to the outer wall of the furnace. The walls of the charcoal stove’s combustion chamber are designed with aluminum plates. A water block cooling system with water flow is used to overcome the increase in heat at the cold side of TEG. The DC water pump power used to circulate the water block is 215 L/h, 275 L/h, 320 L/h, 350 L/h, 375 L/h, and 400 L/h. This research aims to find the most optimal water flow rate at a water block. Temperature measurements are carried out on the recent and bloodless facets of the TEG, and the temperature of the inlet and outlet water of the water block. Changes in TEG voltage, current, and output power are recorded with a multimeter connected to the acquisition data. Analysis of energy balance and heat transfer was carried out in the furnace’s combustion chamber. The experimental results show that the cooling water flow rate of 275 L/h can produce the highest electrical power, around 11.17 W. The use of TEGs as a medium for generating electrical energy from wasted heat through the furnace’s walls can meet some of a household’s electrical energy needs. Full article

The article examines a method of loading biomass waste into a boiler unit, which ensures the gas tightness of the boiler’s working chamber by forming a “plug” of biomass as it moves through the cylindrical channel of the screw feeder. Local biomass wastes (sunflower husks, coniferous wood sawdust, and walnut shells) were selected for the study, a distinctive feature of which is that they did not undergo any prior processing before use (drying, fractionation, grinding, etc.). The properties of biomass as a bulk material (angle of internal friction) were determined experimentally. According to the results, sawdust from coniferous wood has an average angle of internal friction that is 1.48 times bigger than that of sunflower husks and 1.29 times bigger than walnut shells, while the average loading mass of sawdust is 2.2 times less than that of sunflower husks and 2.6 times less than that of walnut shells. This low bulk density and high angle of internal friction for sawdust suggest the likelihood of spontaneous compaction and layer suspension. Experimental studies were also conducted on the compaction force of the biomass layer. It was found that neither coniferous wood sawdust nor walnut shells can be used in the proposed feeder because the sawdust forms a dense layer that does not disperse under any compaction, and the walnut shells do not form a “plug” in the studied pressure range. Therefore, only sunflower husks were used for further studies. The empirical dependence of the density of the sunflower husk layer on the compaction pressure was obtained from the results. It was determined that to ensure a suction level through a screw feeder with a diameter of 0.1 ÷ 0.25 m into the furnace of the boiler unit of no more than 0.1 m³/h with a pressure difference between the boiler furnace and the surrounding environment ΔP = 0.05 ÷ 0.3 kPa, the relative increase in the density of the “plug” from sunflower husks should not exceed the bulk density of the uncompacted layer by more than 11.5%. Experimentally, it was determined that the geometric dimensions of the “plug” from sunflower husk, which ensure the necessary level of gas tightness of the feeder, depend only on the diameter of the channel and are 1.136·d. Calculations were made to obtain the dependencies of the compaction force of the biomass waste layer on the level of suction (in the studied range Q = 0.01 ÷ 0.1 m³/h) into the furnace of the boiler unit under controlled pressure drops (in the studied range ΔP = 0.05 ÷ 0.3 kPa) between the boiler furnace and the surrounding environment for feeders with different screw diameters (d = 0.1 ÷ 0.25 m), which can be used for the practical determination of the geometric and operational parameters of the screw feeder when operating a boiler unit on sunflower husks. Full article

Biomass syngas can be considered as a supplementary fuel to partially substitute coal, which is beneficial to CO₂ emission reduction. For the case study, the influences of co-firing typical biomass syngas (gasification from palm, straw, and wood) with coal on the thermodynamic parameters of a 300 MW tangentially fired boiler are evaluated through a thermal calculation based on the principles of mass conservation, heat conservation, and heat transfer. The effects of boiler loads, biomass syngas species, and consumption rates are discussed. The results show that the introduction of biomass syngas weakens the radiative characteristics of the flame and reduces the furnace exit flue-gas temperature. As 3 × 10⁴ m³ h⁻¹ of wood syngas is introduced, the decrement of thermal efficiency reaches 0.4%, while that of the coal consumption rate is 5.1%. The retrofitting of the boiler was not necessary and the corrosion of the low-temperature heating surface did not appear. The CO₂ annual emission reduction could achieve 0.001 to 0.095 million tons for palm syngas, 0.005 to 0.069 million tons for straw syngas, and 0.013 to 0.107 million tons for wood syngas with increasing biomass syngas consumption rates under the full load. Moreover, the main thermodynamic parameters changed more significantly under the low loads. Full article

This study investigates the suitability of different lignocellulosic sources, namely eucalyptus, apple bagasse, and out-of-use wood, for injection into blast furnaces (BFs). While wastes possess carbon potential, their high moisture renders them unsuitable for direct energy utilization. Additionally, the P and K impurities, particularly in apple bagasse, can pose operational and product quality challenges in BF. Thus, different thermochemical processes were performed to convert raw biomass into a more suitable carbon fuel. Low-temperature carbonization was selected for eucalyptus, yielding a biochar with properties closer to the low-rank coal. Hydrothermal carbonization was chosen for apple bagasse and out-of-use wood, resulting in hydrochars with enhanced fuel characteristics and fewer adverse inorganic species but still limiting the amount in binary PCI blends. Thermogravimetry evaluated the cause–effect relationships between coal and coal- and bio-based chars during co-pyrolysis, co-combustion and CO₂-gasification. No synergistic effects for char formation were observed, while biochars benefited ignition and reactivity during combustion at the programmed temperature. From heat-flow data in combustion, the high calorific values of the chars were well predicted. The CO₂-gasification profiles of in situ chars revealed that lignin-rich hydrochars exhibited higher reactivity and conversion than those with a higher carbohydrate content, making them more suitable for gasification applications. Full article

In response to climate change, wood pellets have been increasingly utilized as a sustainable energy source. However, their growing utilization increases the production of wood pellet fly ash (WA) by-products, necessitating alternative recycling technologies due to a shortage of discharging landfills. Thus, this research seeks to utilize WA by developing a new sustainable construction material, called wood pellet fly ash blended binder (WABB), and to validate its stabilizing performance in natural soils, namely weathered granite soil (WS). WABB is made from 50% WA, 30% ground granulated blast-furnace slag (GGBS), and 20% cement by dry mass. WS was mixed with 5%, 15%, and 25% WABB and was tested for a series of unconfined compressive strength (q_u), pH, and suction tests at 3, 7, 14, and 28 days. For the microstructural analyses, XRD, SEM, and EDS were employed. As the WABB dosage rate increased, the average q_u increased by 1.88 to 11.77, which was higher than that of compacted WS without any binder. Newly cementitious minerals were also confirmed. These results suggest that the effects of the combined hydration mechanism of WABB are due to cement’s role in facilitating early strength development, GGBS’s latent hydraulic properties, and WA’s capacity to stimulate the alkaline components of WABB and soil grains. Thus, this research validates a new sustainable binder, WABB, as a potential alternative to conventional soil stabilizers. Full article