1,720,971 research outputs found
Sega-Spacca Legna Tollot S400. Automazione per legna da ardere di qualità
Full text linkLa produzione della legna da ardere è stata per secoli alla base dello sviluppo di intere civiltà, in quanto ha rappresentato una fondamentale e primaria fonte di energia. L'attuale crescente dinamismo del mercato della legna da ardere ha portato allo sviluppo e al miglioramento di tecnologie in grado di lavorare il legno più efficientemente, riducendo di molto il tempo e il lavoro richiesto per la sua produzione, nonché il rischio di incidenti per gli operatori. Ciò è stato realizzato progettando macchine con produttività e standard ergonomici via via crescenti, in grado di lavorare tronchi con una grande variabilità di diametri e dimensioni, cercando di mantenere i costi di produzione più bassi possibile. Per contro i prezzi di acquisto di tali macchinari sono superiori a quelli usati in metodi di produzione più semplici e tradizionali, e ciò può rappresentare un potenziale limite alla loro diffusione
Study on the optimization of the pellet production and on the development of a forest-wood-pellet chain
Full text linkThe biomass and biofuels markets have increased substantially in the last two decades, mainly driven by the national and European policy targets on green energy. The same positive trend is registered in particular for wood pellet markets.
In comparison with other wooden biofuels (firewood or wood-chips) pellets have a number of positive aspects such as:
- regular and optimized shape;
- wide range of energetic applications (to produce thermal energy, syngas, electricity);
- high solid density resulting in the concentration of a huge amount of energy in small volume;
- high calorific value on volume bases (i.e.: energy density);
- high energetic conversion factors due to the efficiency and regularity of their burning;
- possibility to enhance the qualitative parameters of some biomasses or bio-wastes in a recycling perspective.
The supply chains of wood pellets were traditionally based on residues and by-products from the lumber production industry which could be purchased at low cost locally. Even if these raw materials represent the best option, the potential of residual biomasses has now already reached its availability limit and new forms of supply are needed.
The research program aims to verify the technical and economical feasibility to develop and improve alternative raw materials supply chains for wood pellet production verifying their qualitative output and environmental performances compared with traditional ones.
The research will consider the forestry sector as main source of raw material, as a large amount of low quality timber is annually harvested and even bigger amounts of allowable annual cut (AAC) are not actually harvested both for technical or economic issues. The possibility to build a forest-wood-pellet chain is going to be studied and tested.
The project is mainly focus on four pillars:
1) The study of the actual quality of commercial pellets in the market. Through a consistent sampling activity and the statistical elaboration of the acquired data via SIMCA modeling it is possible to build a model able to classify each sample and predict its certifiability. The model defines a critical metric distance below which a sample can be considered of certifiable quality.
2) The study of the achievable quality that can be technically obtained from forestry assortments. A experimental design is established for the sampling of different raw material retrievable form forest operation in the alpine region. The analysis of wood pellets, produced by the mean of a pilot pelletizing plant, give answers about the quality of the final product.
3) The study of the color of pellets and its relationship with quality parameters. The color of each sample from point 1) is measured through a spectrometer and image scanner and the results elaborated and statistically analyzed to find correlation between color and quality parameter of pellets.
4) The impact assessment of different supply and production pellet chains with the LCA methodology. Five supply and production scenarios are studied and discussed from their environmental performance point of view. Each of them is separated into elementary processes involved in the whole chain and their energetic input and emission output studied and analyzed to detect the best option possible compared with reference one.
The results of this study show that there are still chances of improvement in the production potential of wood pellets by an optimal organization of the supply, not only of traditional raw materials, but also of innovative ones. Their exploitation, moreover, can find a proper position in the market of commercial pellets since the quality performance of such products is comparable with traditional ones
Assessment of work quality of a combined saw and splitter processor
No full textThe growing interest about wood as fuel regards not only wood chips and pellets but also firewood,
especially in mountain and rural areas where domestic heating plants are widely used. Due to the
increased national market demand of firewood, harvesting activities have extended on broadleaved high
forests as well as coppice. As consequence the diameter of logs has increased requiring larger and larger
splitting machines; nowadays it is not uncommon to find on the market splitters able to process logs with
diameter up to 50-60 cm. In order to enhance the productivity, the effort of machine producers is directed
to obtain the complete splitting of the log into firewood in only one step using multiple ways splitting
knives. This technical solution may cause some drawbacks especially when the splitting knives are not
properly adapted to the log diameter; it happens that the size of firewood is not homogeneous and some
splinters are produced, which require to use screens to separate them from the main product.
In order to evaluate the work quality of a combined saw and splitter processor, equipped with a multiple
ways splitting knives, an experimental test has been carried out using a machine in which the log
diameter is automatically detected through a laser device; according to the log diameter the multiple
ways splitting knives (formed by fixed and mobile knives, the latter hydraulically operated) is properly set
up to obtain regular sized firewood. Furthermore the log is automatically centered respect the splitting
knives.
The results of the experimental test showed that, independently from the log diameter, the combined saw
and splitter processor is able to produce firewood with homogeneous size and with a low production of
splinter
Environmental impact assessment of wood products for bioenergy in Europe
No full textIn the last years the world energy demand has rapidly increased as a consequence of the worldwide economic growth and development and it is expected to increase faster in the next decades. Therefore the replacement of fossil fuels with renewable resources is considered to be crucial. Among different ways of producing renewable energy, biomass represents one of the most promising energy source.
In this context, this work aims to compare the environmental impacts of different biomass supply chains, as firewood and pellet produced in Europe. The differences between the biomass supply chains are assessed through a “gate to grave”. Life Cycle Assessment for the impact categories: Global Warming Potential (GWP) and Ozone Depletion Potential (ODP); Photochemical Ozone Creation Potential (POCP) and Human Toxicity Potential (HTP). The boundary of LCA takes into account the forest operations and does not consider tree seedling, site preparation, fertilizer and herbicide treatments because of the naturalistic silvicultural practice used in Italy.
The environmental impacts were calculated based on the method CML 2001 – Apr. 2013 from the Leiden University. The functional unit is 1 MJ of energy for domestic heating.
The majority of the emissions are constituted of biogenic carbon dioxide produced by the biomass combustion.
In the case of firewood supply chain, the study has outlined that for the short supply chain the critical phase of the life cycle in terms of GWP, POCP and HTP is combustion. Moving to the long supply chain, the on-road transport is the most critical phase: the contribution to GWP becomes more than double than the short supply chain and five times higher to ODP.
Concerning the pellet supply chain, it was found that some specific processes (burning, drying, pelletizing) are the biggest contributors for all the four impact categories.
Comparing the two biomass production, firewood shows the lowest impacts because of the less energy intensive production processes.
Although most of the chemicals emitted in the life cycle of biomass cannot be offset, a sustainable naturalistic forest management, common practice in Italy, can completely offset the fossil CO2 emissions, the largest emissive component of greenhouse gases
Qualità del cippato. I nuovi standard UNI EN e la loro applicazione nel settore forestale
Full text linkThe main requirements for the quality classification of woodchips are reported according to the latter version of the European norm UNI EN 14961: 2010, recently updated by the CEN committee. An interview was then submitted to a group of forest woodchips producers working in 10 provinces within Northern and Central regions in Italy, in order to verify the actual following of the norm in the Country. Moreover the interview has documented and verified the actual methods, adopted by producers,
to differentiate the woodchips production based on the observed quality of the produc
Conoscere il cippato: caratteristiche qualitative e requisiti tecnici degli apparecchi termici
Full text linkThe quality of woodchips for energy use is defined by a range of parameters that influence different sectors of the woodenergy chain. The origin of raw material, logistic and
production system are the main parameters that influence
the quality, the market value and the type of plant which
will be adapt to use a specific woodchips. A survey was
made in 47 laboratory samples of wood chips from forest
material, sawmills and agricultural pruning, with the aim
to verify the compliance with normative UN EN 14961-
4:2011. In the last step information about heating plants characteristics and components have been given
Productivity and quality performance of an innovative firewood processor
Full text linkThe growing interest about wood as fuel regards not only wood chips and pellets but also firewood, especially in mountain and rural areas where domestic heating plants are widely used. Due to the increased demand for firewood, harvesting activities have extended on broadleaved high forests as well as coppice. As a consequence, the diameter of logs has increased requiring larger and larger splitting machines; nowadays it is not uncommon to find on the market splitters able to process logs with diameter up to 50-60 cm. In order to increase the productivity, the effort of machine producers is directed to obtain the complete splitting of the log into firewood in only one step using multiple ways splitting knives. This technical solution may cause some drawbacks especially when the splitting knives are not properly adapted to the log diameter; it happens that the size of firewood is not homogeneous and splinters are produced, which requires using screens to separate them from the main product. In order to evaluate the work quality of a firewood processor, equipped with multiple ways splitting knives, an experimental test has been carried out using a machine in which the log diameter is automatically detected through a laser device; according to the log diameter the multiple ways splitting knives (formed by fixed and mobile knives, the latter hydraulically operated) is properly set up to obtain regularly sized firewood. Furthermore the log is automatically centred on the splitting knife set-up. The results of the experimental test showed that the firewood processor is able to produce firewood with homogeneous size and with a low production of splinters, regardless of log diameter
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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