This master thesis deals with design of grate biomass boiler with 50 t/h power. A fuel of the boiler is a mixture of contaminated biomass and woodchips. The boiler produces steam with parameters of 4,2 MPa and 420 °C. Stochiometric and thermal calculations are based on given fuel composition and output steam parameters. Heat exchangers are designated in accordance with the calculations. General drawing of the boiler is attached to this document. Anti-corrosion measures are considered, due to chlorine content in biomass. Hydraulic and aerodynamic losses and dew point of the flue gas is calculated in the end.

This thesis describes the design of boilers for wood chips in a gas boiler house. Consisting of boiler house design from concept design suitable heat source to design components necessary for the proper functionality of the boiler house. Part of thesis is compilation of a functional diagram and design of possible solutions.

The goal of this thesis is to work out an introduction to the chip packaging and decapsulation. Further can be found a description of a method leading to dacapsulate concrete chips. Final part is devoted to getting chip pictures using microscope and analysis of the pictures afterwards.

The Brista 1 plant is a wood chip-fired combined heat and power (CHP) plant located near Märsta, northwest of Stockholm, Sweden. The primary purpose of the plant is to supply heat to the northwest district heating grid. In order to meet increasing demand for district heating, Fortum Heat is constructing a second CHP plant next to Brista 1. The Brista 2 plant will use a mixture of municipal and industrial waste as fuel. Due to changes in the European Green Certificate program, the fuel subsidies for wood chips will be significantly reduced. This will cause the Brista 1 plant to incur significantly increased operating costs. The Brista 2 plant, however, will not be affected by these changes and will therefore be much cheaper to run than Brista 1. However, due to the large demand for district heating it will be necessary to run both plants in parallel at certain times in order to meet the heating demand and/or maximize revenue during periods of high electricity demand. A computer program has been constructed using MATLAB which simulates the Brista 1 and 2 plants and their combined operation in both backpressure and direct condensing mode. The results show that the optimum allocation of heat production does not seem to be affected by electricity price assuming both plants are operated in backpressure mode. The reason for this would seem to be that the production costs (fuel, emissions, O&M) are unaffected by the electricity price. Therefore, the allocation which maximizes electrical power production, and thus revenue from electricity sales, will always be favored. In certain cases, it is more profitable to run the Brista 1 plant in direct condensing mode. The reason for this would seem to be that the thermal efficiency is somewhat higher, and that at low electricity prices the revenues from electricity sales do not offset the cost of the reduced heat production.

La gazéification de biomasse lignocellulosique en biogaz fait partie des technologies attractives permettant de s’affranchir des énergies fossiles et de valoriser les déchets agricoles ou forestiers. Néanmoins, le développement de cette technologie est freiné par son rendement énergétique faible et la production de polluants (CO2, NOx…). La pyrolyse/gazéification par voie solaire permettrait alors de pallier certains de ces inconvénients (énergie propre et gratuite, process à haute température produisant moins de polluants). Dans ce contexte, l’objectif de cette thèse est de développer une approche expérimentale et numérique afin de maîtriser les procédés de pyrolyse/gazéification de copeaux de bois pour mieux appréhender le développement de la gazéification solaire. D’abord, un travail détaillé de caractérisation des copeaux de bois a été réalisé, alliant diverses analyses des échantillons mais aussi des analyses basées sur l’utilisation d’images tomographiques au rayon X pour déterminer les propriétés morphologiques et, par simulation numérique, les propriétés effectives de transport des copeaux de bois. Ensuite, des essais avec un four-réacteur à échelle laboratoire ont été réalisés pour étudier le séchage, la pyrolyse et la gazéification des copeaux de bois. Ces essais nous ont permis d’étudier l’influence de paramètres comme la température en séchage et en pyrolyse ou le débit de vapeur d’eau en gazéification. En parallèle, un modèle multi-physique pour la simulation de la pyrolyse a été développé. Cet outil a permis une étude détaillé des phénomènes mis en jeu et, in fine, permettrait d’optimiser le système. Enfin, le design d’un gazéifieur solaire a été réalisé. / Thermochemical conversion of lignocellulosic biomass belongs to attractive technologies which are viable routes to reduce reliance on fossil energy and to enhance carbon conversion efficiency. Nevertheless, classical gasification process via autothermal combustion of biomass presents severe drawbacks as bad yield and produced important pollutants. Solar concentrated energy enables high temperature reactions with reduced contaminating gas and higher yield. In this context, this thesis aims at developing experimental and numerical approaches to study detailed mechanism of pyrolysis and gasification processes of wood chips packed bed which are key step toward designing efficient solar gasifier. In a first time, inner properties of wood (initial composition and thermal decomposition) were studied via ultimate and proximate analyzes. Structural and morphological properties of wood chips were computed using image analysis. Effective mass and heat transport properties of the packed bed were assessed via direct numerical simulation combined with X-ray tomographic images. Then a laboratory scale device enabling to characterize pyrolysis and gasification kinetics and gas production was developed. The aim of this experimental work was to understand the impact of parameters such as drying and pyrolysis temperatures, and the steam flow rate during gasification. A multiphysical model of pyrolysis of wood chips packed bed was also developed. It allowed to perform detailed study of pyrolysis physics and in fine it will allow optimizing the pyrolysis/gasification process. Finally, a first design for a solar gasifier was reported and constitutes the basis of further studies.

One of the major cost factors in mechanical pulp production is the electrical energy input. Much of the research in this field has therefore been devoted to an understanding of the mechanisms in the refining process and, consequently, to find ways of reducing the electrical energy consumption. Shear and compression are probably the main types of fibre deformation occurring in refiners for collapsing and fibrillating the fibres into a suitable pulp. In current refiners, the repeated mechanical action of the bars on the fibres consumes large amounts of energy in a treatment of mechanical fibres that is almost random. Fundamental studies of the deformation of wood have indicated that a combination of shearing and compression forces is highly beneficial in terms of fibre deformation with a low energy demand. Pure compression is able to permanently deform the fibre but requires a substantial amount of work, while pure shearing, although being much less energy demanding, does not lead to any permanent deformations. A more suitable application of the shear and compression forces on the wood fibres during the refining process could be a way to develop fibres at a lower energy demand. These ideas have been studied in this work trying to find new ways of saving energy in the mechanical pulping process. The first paper in this thesis discusses the way of producing wood shavings and the introduction of shear/compression deformations in these, as well as the potential benefits of using them instead of wood chips as raw material for TMP production. With the shaving process, high deformations in the wood cells were achieved by the shear and compression forces. This led to energy savings of about 25% at a given tensile index, when compared to traditional chips. The quality of the pulp produced from wood shavings was found to be better than that of the pulp produced from wood chips, when it came to strength properties (except for tear index) and optical properties at comparable energy levels. Another way of reducing energy consumption in refining involving a limited shear combined with compression forces for the mechanical treatment of both wood chips and coarse fibres was also studied. This work shows that such a kind of treatment resulted in a high degree of fibre collapse at low energy demands. The thick-walled transition fibres could even be permanently deformed. Furthermore, refining trials, utilising shear and compression pre-treated chips, showed that the strength properties, except for tear index, along with the optical properties of a TMP could be improved and the electrical energy consumed could be reduced by approx. 100 kWh/tonne, when compared to untreated chips. The results from the pilot trials described in this work could be used as a starting point for further implementation in the industry, in order to identify the most efficient way of producing mechanical pulp with a lower consumption of electrical energy. / QC 20101119

Material degradation and a decrease of fuel quality are common phenomena when storing biomass. A magnitude of 7.8% has been reported to degrade over five months when storing spruce wood chips in the winter in Central Europe. This thesis presents a theoretical study of biomass storage. It includes investigations of bio-chemical, chemical and physical processes that occur during storage of chipped woody biomass. These processes lead to degradation caused by micro-activity, chemical oxidation reactions and physical transformation of water. Micro-activity was modeled with Monod kinetics which are Michaelis-Menten type of expressions. The rate expressions were complemented with dependency functions describing the impact of oxygen, moisture and temperature. The woody biomass was divided into three fractions. These fractions represent how hard different components of the wood are to degrade by microorganisms. Chemical oxidation was modeled as a first order rate expression with respect to the active components of the wood. Two different cases have been simulated during the project. Firstly, an isolated system with an initial oxygen concentration of air was considered. This case displayed a temperature increase of approximately 2˚C and a material degradation less than 1%. The second case considered an isolated system with an endless depot of oxygen. This case resulted in degradation losses around 0.45-0.95% in the temperature range between 65-80˚C during approximately 300 days of storage. The temperature increased slowly due to chemical oxidation.

No description available.

Daugelio tyrimų išvados atskleidžia tai, kad vaikų elgesys, žinios, požiūris į maistą bei sveikatos būklė yra įtakoti maisto reklamos, kuri šiuo atžvilgiu skatina vaikų nepalankių sveikatai maisto produktų pasirinkimą. Darbo tikslas – įvertinti reklamos įtaką Vilniaus miesto mokyklų 5, 7, 9 klasių mokinių maisto produktų pasirinkimui. Tyrimo metodai ir apimtis. Tyrimas atliktas pirmąjį mokslo metų pusmetį (spalio, lapkričio, gruodžio mėnesiais). Apklausti Augusto pagrindinės mokyklos, Radvilų gimnazijos, Minties gimnazijos, Šeškinės vidurinės ir Antano Vienuolio pagrindinės mokyklos 5, 7, 9 klasių mokiniai. Išdalinta 650 anketų, 14 anketų buvo grąžintos tuščios (mokiniai sirgo), 31 anketa atmesta, nes nebuvo atsakyta į anketos klausimus arba jos buvo tiesiog sugadintos. Atsako dažnis 93,1%. Statistikai duomenys apdoroti naudojantis statistinės analizės ir duomenų apdorojimo programine įranga – SPSS (16 versija), WINPEPI ir Microsoft Excel programa. Rezultatai ir išvados. Didžioji dauguma mokinių (80%) kasdien pusryčiauja, pietauja ir vakarieniauja. Aukštesnių klasių mergaičių, praleidžiančių pagrindinius valgymus, daugiau nei berniukų. Šiek tiek mažiau nei pusė mokinių vadovaujasi sveikos mitybos piramide ir vaisius valgo kiekvieną dieną. Kasdien daržoves valgančių mokinių dalis siekia trečdalį. Bulvių traškučius ir saldžiuosius gėrimus dauguma respondentų perka retai. Šiek tiek mažiau negu pusė mokinių, siekdami, kad tėvai jiems nupirktų išreklamuotą maisto produktą... [toliau žr. visą tekstą] / Many foreign scientific researches has revealed that children's behavior, knowledge, approach to food and health status are influenced by food advertising. This fact has negative health impact on children's food choices. Goal - to assess the impact of advertising on 5th, 7th, 9th classes student's food choice in schools of Vilnius city. Methods and scope of research. The research was made on the first half of the school year (in October, November and December). 5th, 7th, 9th classes students of 5 schools in Vilnius city: Žygimantas Augustas primary school, Radvilų gimnasium, Minties gimnasium, Šeškinė high school, Antanas Vienuolis primary school, were surveyed. 650 questionnaires were distributed, 14 questionnaires were returned blank (pupils were ill), 31 questionnaires rejected because an answers were illogical. The response rate is 93,1%. Statistical data processing was done using statistical analysis and data processing software - SPSS (version 16), WINPEPI and Microsoft Excel. Results and conclusion. The majority of students (80%) on a daily basis has breakfast, lunch and dinner. Higher grade girls spent their main meals, more than boys. Less than half of students follow a healthy diet pyramid and eat fruit every day. One third of students eat vegetables every day. Potato chips and sweet drinks by most respondents are buying rare. Only a third of parents buy advertised food for children, but that rarely do. Although about 90% of the students themselves buy an advertised... [to full text]

Depuis deux décennies, le bois-énergie se développe fortement en Franche-Comté, notamment dans le secteur collectif/tertiaire. Face à l'épuisement prochain des connexes de scierie, la plaquette forestière (bois déchiqueté) est amenée à se développer. La question de l'approvisionnement devient alors centrale pour l'ensemble des acteurs de la filière, soulevant un grand nombre d'enjeux en matière d'aménagement territorial et forestier, de développement local, d'environnement... Parallèlement, des interrogations émergent : quelle quantité d'énergie peut-on mobiliser durablement ? La configuration spatiale et structurelle des espaces boisés a-t-elle une influence sur les processus d'approvisionnement ? Cherche-t-on à minimiser les distances de transport ? Existe-t-il des phénomènes de concurrence spatiale entre les chaufferies ? Afin de comprendre l'organisation actuelle des approvisionnements, nous avons analysé deux jeux de données de traçabilité de plaquettes forestières. Puis, nous avons développé une démarche visant à modéliser des bassins d'approvisionnement locaux, tenant compte des contraintes de renouvelabilité de la ressource, et des conflits d'usage, en couplant diverses sources d'information : indices de végétation issus de l'imagerie satellitaire, données dendrométriques, cartographie forestière, et tables de production. L'objectif de cette démarche était double : d'une part savoir si les deux terrains d'études choisis étaient en mesure d'assurer eux-mêmes l'approvisionnement de leurs propres chaufferies, d'autre part mettre en évidence les phénomènes de concurrence spatiale des différents bassins d'approvisionnement, et la contribution des différents types de peuplement. Cela a notamment permis de montrer l'importance du gisement énergétique des arbres isolés, à notre connaissance encore jamais évalué à une échelle infra-régionale. / In a context of strong increase of fuelwood demand in the collective sector, the supply issue becomes central to all stakeholders, raising many issues relating to land and forestry planning, local development, environment ... Meanwhile, questions emerge: how much energy can be mobilized sustainably? Does the spatial and structural configuration of forests influence the supply process? Do we seek to minimize transport distances? Can we observe spatial competition between the boilers ? To understand the current organization of supplies, we analyzed two sets of data traceability of wood chips. Then, we have developed a model of local supply basins, considering constraints of renewability of the resource, and conflicts of use, by combining various information sources: vegetation index derived from satellite imagery, forest mapping and production tables. The objective of this approach was dual : to determine the quantity of forest chips workable on a territory, and to highlight the spatial competition between the different basins supply, and the contribution of different tree species. This has enabled to show the importance of the energy potential of isolated trees, to our knowledge not previously evaluated in a sub-regional scale.