Förbränning av pellets framställda av defibrerad granråvara

Fuel pellets are in Sweden mainly produced from sawdust and cutter shavings. Before the pelletising process the raw material is dried to attain consistent moisture content and ground up in a hammer mill. In the densification process (pelletising) the ground material is forced through holes in a rotating die. This heats up the wood particles which cause them to soften and self bond. After the process the pellets are cooled, sieved and bagged. The milling process creates a wide range of particle sizes. How the particle size distribution influences the characteristics of pellets are still rather unclear although it is generally assumed that a mixture of particle sizes will increase pellet durability. The influence of particle size distribution of a pellet on burning characteristics is not known. In pulp mills the woody raw material is usually converted into chips which thereafter are treated in a defibrator into fibre bundles. Such a material is physically different from a mill ground material. One of the main aims of this work was to investigate the burning characteristics of pellets produced from defibrated spruce wood and to compare these pellets with pellets made from mill ground saw dust. The influence of saw dust particle size distribution on burning characteristics was also evaluated for industrially produced and laboratory made pellets. It was found that the char combustion time of pellets made from defibrated wood was somewhat longer than that of saw dust pellets. Anyhow, the differences were not statistically significant. The particle size distribution of the saw dust did affect the burning characteristics e.g. pellets made of a coarse fraction had faster char combustion than pellets made from a fine fraction. The investigation also revealed that during the pelletising (densification) process the saw dust was grinded to smaller particle sizes.Idag används i huvudsak sågspån, kutterspån och flis som pellets råvara. Hammarkvarnar används ofta vid sönderdelning av råvaran innan pelletering. Massaindustrin däremot använder raffinörer som sönderdelare och får en s.k. defibrerad fiber vilken är helt olik den som hammarkvarnen producerar. Syftet med detta arbete var att undersöka förbränningsegenskaperna och förbränningsförloppet för pellets producerad av defibrerad granråvara. Även inverkan av råvarans fraktionsfördelning (fraktionsstorleken) på förbränningsförloppet undersöktes. Pellets pressade av två olika fraktionssammansättningar och en industriproducerad referenspellets undersöktes (förbrändes). Det som framkom antyder goda förbränningsegenskaper för raffinör pellets, däremot tycks fraktionsstorleken ha en inverkan på förbränningsförloppet. Pelleteringsegenskaperna var inte optimala för defibrerat material och det var stora problem att pressa materialet. Hållfasthet och densitet på de pellets som pressades motsvarade dock standardvärden för kommersiell pellets. Vissa intressanta observationer gjordes, bland annat att fraktionsfördelning förändrades vid pelleteringen pga. en malningseffekt i pressen. Vid slipning av pelleten upptäcktes problem med hållfastheten som antyder att tendensen till smulning är större i pelletens konvexa del sedd i pressriktningen än i den andra änden

Dewatering properties of pulps made from different parts of a Norway spruce (Picea abies)

A single Norway spruce tree (Picea abies) was manually fractionated into heartwood, sapwood, juvenile wood and branches. These fractions were chemically pulped, individually, in laboratory scale. The pulps were characterized and investigated in relation to dewatering behavior and sheet strength properties. An unbleached and unbeaten commercial kraft pulp from softwood fibers was used as a reference, and the fractionated pulps were within the same range in all tested properties. The fractionated pulps were then compared with each other, and fiber characteristics were used to explain differences in dewatering and strength. Heartwood pulp results in stronger and stiffer papers that are harder to dewater. Sapwood pulp gives more open network structures resulting in easy dewatering and high air permeance, although with lower strength properties compared to heartwood. Pulp from Juvenile wood gives s quite strong but brittle sheets, with efficient dewatering. Pulp from branches gives paper sheets with efficient dewatering, air permeance and relatively high elongation of break but lower strength. The results show that there is definitely potential for utilizing more parts of the trees for pulp and paper making, especially when tailoring the raw material origins after preferred paper properties

Influence of Sapwood/Heartwood and Drying Temperature on Off-Gassing of Scots Pine Wood Pellets

Wood pellets produced from fresh sawdust can form and release uncontrolled gases during bulk storage, a tendency referred to as off-gassing. This study investigated the off-gassing tendencies of Scots pine wood pellets made from separated sapwood and heartwood sawdust. The effects of drying temperature, raw material storage, as well as varying proportions of sapwood and heartwood were also investigated. There was a strong linear correlation between off-gassing and sapwood content, with correlation coefficient (R) values greater than 0.9 at p < 0.001 for all the off-gases. An increase in sapwood content of the feedstock led to a significant increase in off-gassing of CO2, CO, and CH4, and O-2 consumption. The drying temperature of the raw material had a significant effect on off-gassing of both sapwood (F-(8,F- 26) = 51.32, p < 0.05) and heartwood (F-(8,F- 26) = 334.1, p < 0.05) pellets. Increasing the drying temperature for heartwood resulted in increased off-gassing, while for sapwood, the off-gassing reduced. Storage of sapwood raw material before pelletization reduced the off-gassing of wood pellets, whereas for heartwood, it had no significant impact. Based on the results, it is suggested that a biological process, in combination with the chemical oxidation of fatty acids, lay behind the off-gassing of wood pellets

Influence on off-gassing during storage of Scots pine wood pellets produced from sawdust with different extractive contents

Off-gassing and self-heating are the major challenges when it comes to transportation and storage of wood pellets. The heat generated due to self-heating poses a fire risk while off-gassing of toxic gasses such as carbon monoxide (CO) and some volatile organic compounds (VOCs) is an environmental and human health risk. With the increase in production volumes of wood pellets which has subsequently increased the amounts of wood pellets in transportation and storage, there is need to find lasting solutions to off-gassing and self-heating of wood pellets. The objective of this study was to test the off-gassing abilities of Scots pine wood pellets produced from sawdust with varying amounts of extractives. The aim is to come up with raw material pre-treatment measures so as to produce wood pellets that are not liable to off-gassing. Six (6) types of sawdust raw materials namely; fresh pine sawdust (FPS), stored pine sawdust (SPS), sawdust plus pine rosin (PRS), sawdust plus linseed oil (LOS), sawdust plus tall oil (TOS) and acetone extracted sawdust (AES) were used to produce the pellets. The produced pellets were then subjected to off-gassing tests under controlled conditions using the ECOM J2KN analyser. The concentrations of carbon monoxide, carbon dioxide and methane increased with storage time but slowed down towards the end of the nine days test period. The formation of these gasses were largely dependent on the type of extractives present in the raw material and not the total extractive content. The formation of methane started later than the other gases and coincided with the time when residual oxygen was depleted

Understanding Off-Gassing of Biofuel Wood Pellets Using Pellets Produced from Pure Microcrystalline Cellulose with Different Additive Oils

Fuel wood pellets have the tendency of undergoing self-heating and off-gassing during storage and transportation. Self-heating can lead to spontaneous combustion and cause fires while toxic gasses such as carbon monoxide and some volatile organic compounds released due to off-gassing are a human health and environmental hazard. Previous research suggests that the self-heating and off-gassing of wood pellets are as a result of the oxidation of wood extractives. The aim of this study was to identify the extractives, i.e., fatty and resin acids that are responsible for the emissions of carbon monoxide, carbon dioxide and methane from wood pellets by testing the off-gassing tendencies of pellets produced from synthetic microcrystalline cellulose and different additive oils. The additive oils were intentionally selected to represent different types of wood extractives (mainly fatty and resin acids) and they included: tall oil, pine rosin, linseed oil and coconut oil. The highest mean concentrations of carbon monoxide, carbon dioxide and methane were recorded from cellulose pellets with added linseed oil. The concentrations of carbon monoxide and methane for the other four pellet types were negligible and there was no carbon dioxide emission. Pellets with added linseed oil had high off-gas emissions due to the high content of unsaturated fatty acids compared to other pellet types

Стимулирование сбыта как инструмент повышения эффективности маркетинговой деятельности промышленного предприятия (на примере ОАО "Гомельхлебпром")

Several strains of fungi were isolated and identified from Scandinavian soil using agar plates with lignin as a carbon source. The strains grew significantly faster on this medium than on control plates without lignin. Different types of technical lignins were used, some of which contained trace amounts of sugars, even if the increased growth rate seemed not related to the sugar content. Some strains were cultivated in shaking flask cultures with lignin as a carbon source, with lignin apparently consumed by microbes - while accumulation of the microorganism biomass occurred. The cell-free filtrates of these cultures could reduce the apparent molecular weights of lignosulphonates, while the culture filtrate of one strain could cleave the beta-O-4 bond in a lignin model compound.QC 20160223</p

Neuronal cell-based high-throughput screen for enhancers of mitochondrial function reveals luteolin as a modulator of mitochondria-endoplasmic reticulum coupling

Background: Mitochondrial dysfunction is a common feature of aging, neurodegeneration, and metabolic diseases. Hence, mitotherapeutics may be valuable disease modifiers for a large number of conditions. In this study, we have set up a large-scale screening platform for mitochondrial-based modulators with promising therapeutic potential. Results: Using differentiated human neuroblastoma cells, we screened 1200 FDA-approved compounds and identified 61 molecules that significantly increased cellular ATP without any cytotoxic effect. Following dose response curve-dependent selection, we identified the flavonoid luteolin as a primary hit. Further validation in neuronal models indicated that luteolin increased mitochondrial respiration in primary neurons, despite not affecting mitochondrial mass, structure, or mitochondria-derived reactive oxygen species. However, we found that luteolin increased contacts between mitochondria and endoplasmic reticulum (ER), contributing to increased mitochondrial calcium (Ca2+) and Ca2+-dependent pyruvate dehydrogenase activity. This signaling pathway likely contributed to the observed effect of luteolin on enhanced mitochondrial complexes I and II activities. Importantly, we observed that increased mitochondrial functions were dependent on the activity of ER Ca2+-releasing channels inositol 1,4,5-trisphosphate receptors (IP3Rs) both in neurons and in isolated synaptosomes. Additionally, luteolin treatment improved mitochondrial and locomotory activities in primary neurons and Caenorhabditis elegans expressing an expanded polyglutamine tract of the huntingtin protein. Conclusion: We provide a new screening platform for drug discovery validated in vitro and ex vivo. In addition, we describe a novel mechanism through which luteolin modulates mitochondrial activity in neuronal models with potential therapeutic validity for treatment of a variety of human diseases

Is it possible to describe practical skill from a technical point of view to facilitate an improved skill and ability in the practical discipline?

I detta dokument belyses praktisk färdighet utifrån en teknisk synvinkel. Färdigheten delas upp i mindre beståndsdelar. Dessa beståndsdelar beskrivs var för sig och på vilket sätt de bidrar till samt påverkar den praktiska färdigheten.   Syftet med arbetet är att visa hur den läroprocess som eleven genomgår vid träning av en praktisk disciplin kan tydliggöras och underlättas, genom att utgå från ett tekniskt perspektiv.   Det bör betonas att praktisk färdighet studeras enbart utifrån ett tekniskt perspektiv. Det ger många möjligheter att analysera färdigheten, men synsättet ger även upphov till begränsningar avseende en total förståelse av vad praktisk färdighet är. Nedanstående arbete bör därför ses som en modell eller beskrivning som liksom andra modeller och beskrivningar ger vissa insikter, men som också har begränsningar i sin giltighet.   Resultatet visar att praktisk färdighet kan betraktas och analyseras utifrån sina tekniska beståndsdelar. Därmed kan en optimal praktisk färdighet definieras och utgöra ett mål för den praktiska träningen. Även en redan intränad färdighet, som av någon anledning anses innehålla inslag av olämpliga moment, kan tränas om så att den bättre stämmer överens med den optimala färdigheten.   Det tekniska synsättet fungerar väl i ett inledande skede av det praktiska lärandet, där det handlar om att lära sig grundläggande handlag inom den praktiska disciplinen. Huruvida det fungerar även i senare skeden där förtrogenhet utvecklas, har inte undersökts här. Det tekniska perspektivet gör det även möjligt att studera hur olika träningsmetoder påverkar det praktiska lärandet

Att reparera skiftesverkshus

Skiftesverket har stora likheter med möbeltillverkningen: alla dess delar kan göras färdiga före hop­sättningen. Det går att rusta upp ett skiftesverkshus med hjälp av enbart trävirken och receptet till­handahåller byggnaderna själva. Denna lärdom får vi från Öland, förmedlad av arkitekt Gunnar Henriksson, kännare av öländska hus i allmänhet och skiftesverks­hus på Öland i synnerhet.