999 resultados para Volcanic ash, tuff, etc.
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1827 (VOL2).
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In Finland the thermal treatment of sewage sludge has been moderate in 21th century. The reason has been the high moisture content of sludge. During 2005-2008, 97-99% of sewage sludge was utilized in landscaping and agriculture. However agricultural use has been during 2005-2007 less than 3 %. The aim of national waste management plan is that by 2016 100% of sludge is used either as soil amendment or energy. The most popular utilization method for manure is spreading it on arable land. The dry manures such as poultry manure and horse manure could also be used in incineration. The ashes could be used as fertilizers and while it is not suitable as a starter fertilizer, it is suitable in maintaining P levels in the soil. One of the main drivers for more efficient nutrient management is the eutrophication in lakes and the Baltic See. ASH DEC process can be used in concentrating phosphorus rich ashes while separating the heavy metals that could be included. ASH DEC process uses thermochemical treatment to produce renewable phosphate for fertilizer production. The process includes mixing of ashes and chlorine donors and subsequent treatment in rotary kiln for 20 min in temperature of 900 – 1 050 oC. The heavy metals evaporate and P-rich product is obtained. The toxic substances are retained in air pollution control system in form of mixed metal hydroxides. The aim of conducting this study is to estimate the potential of ASH DEC process in treating phosphorus rich ashes in Finland. The masses considered in are sewage sludge, dry manure from horses, and poultry and liquid pig manure. To date the usual treatment method for sewage sludge in Finland is composting or anaerobic digestion. Part of the amount of produced sewage sludge (800 kt/a fresh mass and 160 kt/a TS) could also be incinerated and the residual ashes used in ASH DEC process. Incinerating only manure can be economically difficult to manage because the incineration of manure is in Finland considered as waste incineration. Getting a permit for waste incineration is difficult and also small scale waste incineration is too expensive. The manure could act as an additional feedstock in counties with high density of animal husbandry where the land area might not be enough for spreading of manure. Now when the manure acts as a supplementary feedstock beside sludge, the ash can’t be used directly as fertilizer. Then it could be used in ASH DEC process. The perquisite is that the manure producers could pay for the incineration, which might prove problematic.
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Waste combustion has gone from being a volume reducing discarding-method to an energy recovery process for unwanted material that cannot be reused or recycled. Different fractions of waste are used as fuel today, such as; municipal solid waste, refuse derived fuel, and solid recovered fuel. Furthermore, industrial waste, normally a mixture between commercial waste and building and demolition waste, is common, either as separate fuels or mixed with, for example, municipal solid waste. Compared to fossil or biomass fuels, waste mixtures are extremely heterogeneous, making it a complicated fuel. Differences in calorific values, ash content, moisture content, and changing levels of elements, such as Cl and alkali metals, are common in waste fuel. Moreover, waste contains much higher levels of troublesome trace elements, such as Zn, which is thought to accelerate a corrosion process. Varying fuel quality can be strenuous on the boiler system and may cause fouling and corrosion of heat exchanger surfaces. This thesis examines waste fuels and waste combustion from different angles, with the objective of giving a better understanding of waste as an important fuel in today’s fuel economy. Several chemical characterisation campaigns of waste fuels over longer time periods (10-12 months) was used to determine the fossil content of Swedish waste fuels, to investigate possible seasonal variations, and to study the presence of Zn in waste. Data from the characterisation campaigns were used for thermodynamic equilibrium calculations to follow trends and determine the effect of changing concentrations of various elements. The thesis also includes a study of the thermal behaviour of Zn and a full—scale study of how the bed temperature affects the volatilisation of alkali metals and Zn from the fuel. As mixed waste fuel contains considerable amounts of fresh biomass, such as wood, food waste, paper etc. it would be wrong to classify it as a fossil fuel. When Sweden introduced waste combustion as a part of the European Union emission trading system in the beginning of 2013 there was a need for combustion plants to find a usable and reliable method to determine the fossil content. Four different methods were studied in full-scale of seven combustion plants; 14Canalysis of solid waste, 14C-analysis of flue gas, sorting analysis followed by calculations, and a patented balance method that is using a software program to calculate the fossil content based on parameters from the plant. The study showed that approximately one third of the coal in Swedish waste mixtures has fossil origins and presented the plants with information about the four different methods and their advantages and disadvantages. Characterisation campaigns also showed that industrial waste contain higher levels of trace elements, such as Zn. The content of Zn in Swedish waste fuels was determined to be approximately 800 mg kg-1 on average, based on 42 samples of solid waste from seven different plants with varying mixtures between municipal solid waste and industrial waste. A review study of the occurrence of Zn in fuels confirmed that the highest amounts of Zn are present in waste fuels rather than in fossil or biomass fuels. In tires, Zn is used as a vulcanizing agent and can reach concentration values of 9600-16800 mg kg-1. Waste Electrical and Electronic Equipment is the second Zn-richest fuel and even though on average Zn content is around 4000 mg kg-1, the values of over 19000 mg kg-1 were also reported. The increased amounts of Zn, 3000-4000 mg kg-1, are also found in municipal solid waste, sludge with over 2000 mg kg-1 on average (some exceptions up to 49000 mg kg-1), and other waste derived fuels (over 1000 mg kg-1). Zn is also found in fossil fuels. In coal, the average level of Zn is 100 mg kg-1, the higher amount of Zn was only reported for oil shale with values between 20-2680 mg kg-1. The content of Zn in biomass is basically determined by its natural occurrence and it is typically 10-100 mg kg-1. The thermal behaviour of Zn is of importance to understand the possible reactions taking place in the boiler. By using thermal analysis three common Zn-compounds were studied (ZnCl2, ZnSO4, and ZnO) and compared to phase diagrams produced with thermodynamic equilibrium calculations. The results of the study suggest that ZnCl2(s/l) cannot exist readily in the boiler due to its volatility at high temperatures and its conversion to ZnO in oxidising conditions. Also, ZnSO4 decomposes around 680°C, while ZnO is relatively stable in the temperature range prevailing in the boiler. Furthermore, by exposing ZnO to HCl in a hot environment (240-330°C) it was shown that chlorination of ZnO with HCl gas is possible. Waste fuel containing high levels of elements known to be corrosive, for example, Na and K in combination with Cl, and also significant amounts of trace elements, such as Zn, are demanding on the whole boiler system. A full-scale study of how the volatilisation of Na, K, and Zn is affected by the bed temperature in a fluidised bed boiler was performed parallel with a lab-scale study with the same conditions. The study showed that the fouling rate on deposit probes were decreased by 20 % when the bed temperature was decreased from 870°C to below 720°C. In addition, the lab-scale experiments clearly indicated that the amount of alkali metals and Zn volatilised depends on the reactor temperature.
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Cellulose fiber-silica nanocomposites with novel mechanical, chemical and thermal properties have potential to be widely applied in different area. Monodispered silica nanoparticles play an important role in enhancing hybrids properties of hardness, strength, thermal stability etc. On the other hand, cellulose is one of the world’s most abundant and renewable polymers and possesses several unique properties required in many areas and biomedicine. The aim of this master thesis is to study if silica particles from reaction of sodium silicate and sulphuric acid can be adsorbed onto cellulose fiber surfaces via in situ growth. First, nanosilica particles were synthesized. Effect of pH and silica contents were tested. In theoretical part, introduction of silica, methods of preparation of nanosilica from sodium silicate, effect factors and additives were discussed. Then, cellulose fiber-silica nanocomposites were synthesis via route from sodium silicate and route silicic acid. In the experiment of route from sodium silicate, the effects of types of sodium silicate, pH and target ratio of silica to fiber were investigated. From another aspect, the effects of types of sodium silicate, fiber concentration in mixture solution and target ratio of silica to fiber were tested in the experiment of route from silicic acid. Samples were investigated via zeta potential measurement, particle size distribution, ash content measurement and Scanning Electron Microscopy (SEM). The Results of the experiment of preparing silica sol were that the particle size of silica sol was smaller prepared in pH 11.7 than that prepared in pH 9.3. Then in the experiment of synthesis of cellulose fiber-silica nanocomposites, it was concluded that the zeta potential of all the samples were around -16 mV and the highest ash content of all the samples was only 1.4%. The results of SEM images showed only a few of silica particles could be observed on the fiber surface, which corresponded to the value of ash content measurement.
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Julkaisussa: Cosmographia : Beschreibung aller Lender durch Sebastianum Munsterum in welcher begriffen
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Irtokartta
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Julkaisussa: Atlas minor
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De douze dessins dʹaprès nature.
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Kartalla: Téatre de la guerre des courones du nord qui comprend les royaumes de Danemark, Suède & Norvège
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Kartta kuuluu A. E. Nordenskiöldin kokoelmaan
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Kartta kuuluu A. E. Nordenskiöldin kokoelmaan
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Kartta kuuluu A. E. Nordenskiöldin kokoelmaan
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Kartta kuuluu A. E. Nordenskiöldin kokoelmaan
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Janamittakaava: Miliaria Germanica.