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The aim of this study was to verify the possibility of obtaining good-quality pellets from mixtures of materials with different particle structures and shapes. The paper describes the pressure agglomeration of ground walnut shells and coniferous tree cones as well as their three mixtures. The process involved the production of pellets with a diameter of 6 and 8 mm at the temperatures of 95 and 120°C by applying the force of 5 and 6 kN. The fraction distribution of the particles from which the pellets were made was assessed. It was found that the pellets made only of cones, as opposed to those made only of nutshells, have a fairly even distribution, i.e. the particles were of similar size. The size parameters of the pellets (length and diameter) were measured, on the basis of which the density of individual pellets was calculated. Compressive stresses of the pellets were tested on an endurance testing machine. It was found that the pellets with a greater share of nut shells were less durable than those made with the addition of ground cones. The pellets with a diameter of 6 mm and formed at a temperature of 120°C also showed a higher strength than those with a diameter of 8 mm and compacted at a temperature of 95°C. Increasing the force did not statistically significantly improve the compressive strength of the pellets. Tests of the elemental composition and the amount of ash allowed for concluding that pellets are a good energy material, as evidenced by their average calorific value of about 19 MJ kg−1. Due to exceeding the permissible limit of nitrogen content (ISO 17225), the pellets made solely of cones were classified as quality class B, while the addition of ground walnut shells shifted them to class A2. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the number of stages of cone drying and immersion that yield the maximum number of high quality seeds. Nine variants of the process were conducted; they differed in terms of dwell time in the drying chamber and water immersion time. Each extraction variant consisted of five drying steps (lasting 10, 8 or 6 h) and four immersion steps (5, 10 or 15 min). Each drying step was followed by cone shaking in a purpose-made laboratory drum. The process variants were evaluated and compared in terms of cone moisture content as well as the dynamics of seed yield and the quality of seeds obtained in the various steps. The seed yield coefficient, α, and the cone mass yield coefficient, β, were calculated. The studied process of seed extraction can be described using the Lewis empirical model for the second stage of drying with the b coefficient ranging from 0.34 to 0.60. Relatively higher initial and final moisture content was found for cones immersed for 15 min (more than 0.45 kgwater·kgd.w.−1), while the lowest moisture content was found for those immersed for 5 min (less than 0.4 kgwater·kgd.w.−1). The highest seed yield at the first and second steps was obtained in the 8 h_10 min variant (53% and 32%, respectively). In all five-step variants, the mean cone yield amounted to 65% of total seeds in the cones; seeds obtained from all variants were classified in quality class I. The procedure recommended for commercial seed extraction facilities consists of three 8 h drying steps and two 10 min immersion steps, with cone shaking in a drum to maximize seed yield. A shorter cone extraction process maintaining an acceptable level of seed extraction may reduce energy consumption by nearly 50%. [ABSTRACT FROM AUTHOR]

The paper analyzes two seed extraction methods used by Polish silvicultural seed extractories. The analysis involves cone batches as well as individual cones processed in extraction cabinets. During thermal extraction, the cones were dried (10 h), moistened with water (10 min), and dried again (10 h). During thermomechanical extraction, the cones were dried for a much longer time (40 h), and then crushed in a mechanical unit (20 min). The two examined cases of seed extraction were compared in terms of the size, weight, and moisture content of the cones involved, the steps in the extraction process, as well as the quantity and quality of the obtained seeds. Each of the extractories made use of cones of a different provenance, which differed significantly from each other. In order to compare the different seed extraction methods, the same batch of cones collected from one geographic locality should be used. The results of a process analysis show that the thermal method was superior in terms of energy efficiency and duration. The seeds extracted using the two methods were of the highest quality (class I), which indicates that in both cases the extraction process was conducted appropriately and did not cause the quality of the seeds to deteriorate. [ABSTRACT FROM AUTHOR]

The influence of short-term microwave irradiation on the process of seed extraction from Scots pine cones was investigated in this study. Cones from the Brzesko Forest District (near Kraków, southern Poland) were collected in 2015. The size and changes in the mass of cones during the process of seed extraction, as well as the relations between these parameters, were analyzed. Changes in water content and drying rate of cones were modeled using suitable mathematical equations. The thermal balance of the whole process of seeds extraction was calculated, and the heat necessary to extract the seeds was determined. Cones were initially exposed to 2.45 GHz microwaves with a power of 800 W for either 5 or 15 seconds. Subsequently, cones were placed in a circulating air oven and seeds extracted under convective drying at a constant temperature of 50 ± 0.1 °C. We found that seeds from cones subjected to 15-seconds microwave radiation were dramatically damaged, while no significant difference were found in germination and quality of seeds between cones subjected to the 5-seconds microwave pre-treatment and control cones, both yielding first-class quality seeds (mean germination capacity > 90%). The results of this study could help developing microwave-dryer control algorithms to support the automated process of cone seed extraction in large-capacity extraction plants. [ABSTRACT FROM AUTHOR]

In this paper, the results of research on the variability of black alder cones (Alnus glutinosa L.) ware presented. The research was carried out for two, significantly different, batches of cones. Basic size parameters and mass were measured. The shape of the cone was determined, and it was described with the fourth-degree polynomial. The surface area and volume of the cone were calculated using the forming curve and formulas for solids: barrel and cylinder. The parameters of cones—shape surface area and volume—were analyzed. It was found that for alder cones (from the researched origins), the average volumes calculated from the barrel formula are 1701 mm3 and 1162 mm3, and the areas calculated from the cylinder formula are 807 mm2 and 597 mm2. The structure of the inner and outer sides of scales was examined using a scanning electron microscope. Using the MultiScanBase v. 18.03 program, the elements of husk structure that could affect the efficiency of seeds extraction were measured. The results of the research can be used to program the process of seeds extraction from alder cones in commercial installations. [ABSTRACT FROM AUTHOR]

The aim of the research was to determine the production viability and mechanical durability of briquettes made of shredded cones of three species: Scots pine, Norway spruce and European larch The agglomeration was carried out under constant operating conditions (at 20% of material moisture content, briquette diameter of 50 mm, at throughput of 50 kg h −1 ) in an industrial briquetting press. The particle size distribution of the shredded material was determined. The produced briquettes were evaluated for their density, mechanical durability and compressive strength. At moisture content of approximately 20%, the highest briquette density (1078 kg m −3 ), durability (97.87%) and compressive strength (9.69 MPa) were obtained for spruce briquettes. Pine cone briquettes showed the lowest density (938 kg m −3 ) and compressive strength (2.81 MPa), while larch cone briquettes had the lowest durability (87.58%). The produced briquettes were of high quality in terms of physical and mechanical characteristics. The novelty of research was the use of crushed cones of coniferous species, which are waste in seed extraction facilities, and due to the low bulk density, they are difficult to store and transport over long distances. After agglomeration, they form briquettes with good physical and mechanical parameters that can be used in local heating plants and stoves. [ABSTRACT FROM AUTHOR]

The paper presents the results of experiments involving the exposure of Scots pine ( Pinus sylvestris L.) cones to microwave radiation. The pine cones were obtained from the Maskulińskie and Brzesko Forest Districts (both in Poland). Pine cone length, thickness, and weight were determined and found to be significantly different between the two locations. Pine cones were exposed to 2.45-GHz microwaves emitted by a horn antenna, which was either fixed or moving at a speed of 0.002 m s over the cones. Total microwave emission time ranged from 30 to 441 s, depending on the test variant. The measured parameters included changes in pine cone moisture content as well as the germination capacity and viability class of the extracted seeds. It was found that pine cone moisture content decreased on average by 0.3 to 6 %, depending on the amount of microwave radiation applied. It was found that pine cone size, the amount of microwave radiation, and the distance between the cones and the horn antenna affected seed germination and viability class. In most experimental variants, the seeds were damaged by microwaves. Viable seeds (classes I and II) were obtained after 30 s of exposure to microwave radiation from a fixed horn antenna positioned at a distance of 0.04 m over the cones. The application of a moving antenna positioned 0.14 m over the cones resulted in seeds of viability classes II and III following a single microwave sweep over the seeds. [ABSTRACT FROM AUTHOR]

The objective of the study was to elucidate the kinematics of cone opening in the European larch (Larix decidua Mill.) during a four-step seed extraction process and to determine optimum process time on that basis. Each step lasted 8 h with 10 min of water immersion between the steps. The study also described the microscopic cellular structure of scales in cones with a moisture content of 5% and 20%, as well as evaluated changes in cell wall thickness. The obtained results were compared with the structural investigations of scales conducted using scanning electron microscopy (SEM) of characteristic sites on the inner and outer sides of the scales. The greatest increment in the scale opening angle was noted on the first day of the process (34°) and in scales from the middle cone segment (39°). In scales with a moisture content of 5% and 20%, the greatest changes in cell wall thickness were recorded for large cells (57%). The inner and outer structure of scales differed in terms of the presence and size of cells depending on the moisture content of the cones (5%, 10%, or 20%). The study demonstrated that the moisture content of cones was the crucial determinant of the cellular structure and opening of scales in larch cones. The scale opening angle increased with decreasing moisture content but did not differ significantly for various segments of cones or various hours of the consecutive days of the process. This finding may lead to reducing the seed extraction time for larch cones. The internal and external structure of scales differed depending on moisture content, which also determined the size and wall thickness of cells. [ABSTRACT FROM AUTHOR]

The paper investigated the torrefaction of cones from three tree species: Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L.), and European larch (Larix decidua Mill.). The objective was to determine the effects of torrefaction temperature on the properties of cones with a view to their further use as a renewable energy source. Torrefaction was conducted at 200, 235, 275, and 320 °C for 60 min under an inert gas atmosphere. Elemental composition, ash content, and lower heating value (LHV) were measured for the original and torrefied samples. Torrefaction performance was evaluated using formulas for solid yield, higher heating value (HHV), HHV enhancement factor, as well as energy yield. Scanning electron microscopy (SEM) was used to assess elemental composition and structural changes at the surface of the torrefied material. For all the studied conifer species, the higher the torrefaction temperature, the greater the carbon and ash content and the higher the LHV (a maximum of 27.6 MJ·kg−1 was recorded for spruce and larch cones torrefied at 320 °C). SEM images showed that an increase in process temperature from 200 to 320 °C led to partial decomposition of the scale surface as a result of lignin degradation. Cone scales from all tree species revealed C, O, N, Mg, K, and Si at the surface (except for pine scales, which did not contain Si). Furthermore, the higher the temperature, the higher the enhancement factor and the lower the energy yield of the torrefied biomass. Under the experimental conditions, spruce cones were characterized by the lowest weight loss, the highest HHV, and the highest energy yield, and so they are deemed the best raw material for torrefaction among the studied species. [ABSTRACT FROM AUTHOR]

While lasers are widely used across various industries, including woodworking, few studies to date have addressed the issue of cutting fresh wood. In the present investigation, wood stemming from fresh tree branches was cut at different laser powers and beam travel speeds. A fiber laser and a CO2 laser were used for the research. The cellular structures of the cut surfaces were examined, with some of them found to be covered with a layer of compacted, charred cells. This may be a favorable phenomenon, preventing the invasion of pathogens via the wounds caused by laser beam branch cutting in nurseries, plantations, and orchards. [ABSTRACT FROM AUTHOR]

Biomass energy for heating is going to be part of the spectrum of renewable energy sources. However, biomass combustion produces emissions of various pollutants with negative effects at both local and global scales. To reduce some of the locally important pollutant load, thermally treated biomass fuels may offer a partial solution. In this study, two biomass feedstocks, i.e., spruce chips and rapeseed straw, were thermally treated at 300 °C to produce biochars. Subsequently, both original materials and biochars were burned in a 25 kW retort combustion device. In both cases, the biochar showed lower emissions of carbon monoxide and nitrogen oxides, usually almost across the whole range of tested combustion conditions. In total, for the emission production per unit of net calorific value, the spruce biochar showed reductions in CO and NOx productions of 10.8% and 14.5%, respectively. More importantly, in rapeseed straw biochar, the difference was more pronounced. The total production was reduced by 28% and 42%, again in CO and NOx emissions, respectively. [ABSTRACT FROM AUTHOR]

As a push towards alternative and renewable resources for heat and power generation, biomass and thermally treated fuels from biomass may be viable options in the upcoming economic reality. This study the verified mass and energy balance of spruce woody biomass after low temperature pyrolysis between 250 and 550 °C. The results showed that low-temperature pyrolysis can yield high-grade biochar suitable for substitution of fossil fuels. Crucially, the net calorific value of biochar processed at 350 °C substantially exceeded that of brown coal. An economic analysis was carried out on the assumption of the current economic reality in the Czech Republic. It was shown that even if the price of the biochar slightly increased, it would still be beneficial to invest in torrefaction technology over paying carbon credits. [ABSTRACT FROM AUTHOR]

Negative environmental impacts related to climate change and social pressure to raise the rotation age of forests contribute to the quality deterioration of harvested wood, including its decomposition by fungi. This paper presents the results of laboratory experiments investigating the decomposition of Norway spruce (Abies alba) and silver fir (Picea abies) wood by selected species of decay fungi: Hericium flagellum and Bondarzewia mesenterica (causing white rot) as well as Rhodofomes roseus (causing brown rot). The decay process affects wood density, elemental composition, net calorific value, as well as the amount and price of the energy contained in the wood. Wood density was measured conventionally using an electronic caliper and laboratory balance. Energy parameters were determined using elemental analyzer and combustion calorimeter. Wood decay was found to adversely affect energy content per unit of wood at a given volume, thus leading to higher prices per unit of energy. Over the 120 days of the experiment, wood parameters were not affected considerably by Hericium flagellum or Bondarzewia mesenterica. Of the three examined fungal species, Rhodofomes roseus caused the highest weight loss of wood and the greatest decrease in its oven-dry density (spruce - a decrease from 409 to 214 kg m−3; fir - a decrease from 420 to 306 kg m−3), unfavorably reducing energy content per 1 m3 of wood (spruce – decrease by 3.8 GJ m−3; fir – decrease by 2.3 GJ m−3) and raising the unit price of energy. [Display omitted] [ABSTRACT FROM AUTHOR]

The use of grape residues as a renewable energy source for combustion presents various problems. One of these is the excessive production of carbon monoxide and nitrogen oxides. Analyses and combustion tests were performed on white and red grape pomace as well as grape stems. To verify the possibility of a reduction in emissions, straw of Miscanthus sinensis was added to mixtures with red grape pomace. Emission concentrations of carbon monoxide and nitrogen oxides were determined on a grate combustion device with a nominal thermal output of 8 kW under steady-state conditions. In addition to these emission concentrations, the excess air factor and the flue gas temperature were monitored. The results show a high energy content in grape residues. In red grape pomace, the gross calorific value of dry matter reached 22.17 MJ kg−1. Unfavourable properties included high ash and nitrogen contents. During combustion tests on all types of grape residue, the emission concentrations of carbon monoxide were above the legal limit for the combustion of solid fuels. The addition of Miscanthus straw improved the behaviour during combustion. The maximum content of grape pomace in the mixture capable of meeting legislative emission requirements was 50% wt. [ABSTRACT FROM AUTHOR]

To maximise the use of biomass for energy purposes, there are various options for converting biomass to biofuels through thermochemical conversion processes, one of which is torrefaction. Higher utilisation of waste from the aspiration cleaning of grains, such as wheat or maize, could be one of the means through which the dependence on fossil fuels could be reduced in the spirit of a circular economy. In this study, the effect of torrefaction on fuel properties of agricultural residues was investigated. The tested materials were waste by-products from the aspiration cleaning of maize grains and waste from wheat. The materials were treated by torrefaction under a nitrogen atmosphere (225 °C, 250 °C, and 275 °C), over a residence time of 30 min. During the treatment, weight loss was monitored as a function of time. Proximate and elemental composition, as well as calorific values, were analysed before and after torrefaction. Torrefaction has a positive effect on the properties of the fuels in the samples studied, as shown by the results. The carbon content increased the most between temperatures of 250 °C and 275 °C, i.e., by 11.7% wt. in waste from maize. The oxygen content in the maize waste samples decreased by 38.99% wt. after torrefaction, and in wheat waste, it decreased by 37.20% wt. compared to the original. The net calorific value increased with increasing temperatures of process and reached a value of 23.56 MJ·kg−1 at a peak temperature of 275 °C in by-products from maize. To express the influence of the treatments on combustion behaviour, stoichiometric combustion calculations were performed. Differences of up to 20% in stoichiometric combustion parameters were found between the two types of waste. A similar case was found for fuel consumption, where a difference of 19% was achieved for torrefaction at a temperature of 275 °C, which fundamentally differentiated these fuels. [ABSTRACT FROM AUTHOR]

• Spruce, pine and larch cones were compared to spruce wood. • The cones had comparable energy content to spruce wood. • Pine cones showed the lowest emission levels, while larch cones had the highest. The aim of the research was to determine selected fuel properties and basic emission characteristics of briquettes made from cones of three tree species: Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies H. Karst.) and European larch (Larix decidua Mill.). Combustion tests were carried out under stabilized operating conditions (heat output, excess air coefficient) on a grate-fired combustion device. The elemental composition of the cone samples and the heating values were determined. The briquettes were evaluated in terms of carbon monoxide and nitrogen oxide emission concentrations depending on the excess air factor and the flue gas temperature. The composition and energy content of the cone materials were comparable to wood. In the dry state, the ash content was between 0.69 and 1.29% wt. and the lower heating values between 18.77 and 19.58 MJ·kg−1. This suggests favourable properties for use as a solid biofuel. However, during combustion all cone briquettes achieved higher emission levels of nitrogen oxides as well as carbon monoxide compared to spruce wood briquettes. Larch cone briquettes were consistently the highest in emissions which reached concentrations of carbon monoxide in flue gas up to 3500 mg·m−3. On the other hand, spruce and pine cone briquettes kept concentrations of carbon monoxide below 2000 mg·m−3 at excess air coefficients under 2.4. The amount of excess air significantly influenced the temperature of the exhaust gas, which was maintained above 300 °C during the tests. In the tested areas and the excess air coefficients the concentrations of nitrogen oxides did not exceed 200 mg·m−3 and were low for all samples. [ABSTRACT FROM AUTHOR]

A significant amount of waste is generated in the food industry, which is both an environmental and an economic problem. The recycling of this waste has become an important area of research. The processing of grapes produces 20–30% of the waste in the form of grape pomace and stalks. This article assesses the fuel values of these materials before and after torrefaction. The input materials were grape pomace samples from the varieties Riesling (Vitis vinifera "Welschriesling") and Cabernet Sauvignon (Vitis vinifera "Cabernet Sauvignon") from the South Moravia region and stalks from the variety Welschriesling. The torrefaction process was performed using a LECO TGA 701 thermogravimetric analyzer under nitrogen atmosphere at set temperatures of 225 °C, 250 °C, and 275 °C. The residence time was 30 min. Elemental analysis, calorific value, and gross calorific value were determined for all samples. The analyses show a positive effect of torrefaction on fuel properties in the samples. Between temperatures 250 °C and 275 °C, the carbon content increased by 4.29 wt.%, and the calorific value increased with the increase in temperature reaching a value of 25.84 MJ·kg−1 at a peak temperature of 275 °C in the sample grape pomace from blue grapevine. [ABSTRACT FROM AUTHOR]

This paper presents the results of the analysis of the chemical composition and content of heavy metal contamination in forest logging residues, in order to assess the possibility for their further utilisation. The samples were divided into 9 groups, which included coniferous tree cones, wood, and other multi-species logging residues. The elementary composition, ash content, and calorific value were determined as energy use indicators for the samples. Additionally, the content of heavy and alkali metals, which may affect combustion processes and pollutant emissions, was tested. The high content of heavy metals may also disqualify these residues for other uses. The research shows that the test residues are suitable for energy use due to their high calorific value and low content of heavy metals. However, an increased ash content in some samples and the presence of alkali metals, causing high-temperature corrosion of boilers, may disqualify them as a potential fuel in the combustion process. The forest residues may be used in other thermal processes such as pyrolysis or gasification. A low content of heavy metals and a high content of organic matter permit the use of these residues for the production of adsorbents or composite materials. [ABSTRACT FROM AUTHOR]