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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 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]

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]

• 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]