Incineration with energy recovery is the main disposal strategy for waste that cannot be reused or recycled, and a well-established source of energy in Europe, especially in Sweden where 2.2 Mtonnes of waste including domestic and imported municipal solid waste (MSW) and waste wood (WW) were combusted during 2015. However, owing to its inherent heterogeneous composition, inclusion of such waste in Waste-to-energy (WtE) technologies is challenging. These heterogeneities may lead to operationally-related issues in the WtE facilities and contribute to toxic emissions, which can be reduced by waste pre-treatment technologies.    This thesis examines the variations in the composition of MSW and WW streams used as a fuel supply in WtE facilities after undergoing waste pre-treatment technologies, and the effect of fuel composition on its combustion behaviour and formation of persistent organic pollutants (POPs) such as polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The overall objective is to contribute to a more thorough understanding of the selection of waste pre-treatment technologies to mitigate harmful emissions into the atmosphere when waste fuels are combusted in WtE facilities.    This thesis describes the high variability of contaminants in domestic and imported WW and suggests adaptation of WW pre-treatment techniques to produce fuels with a low potential for generating pollutants. A comparison of mechanical solid waste pre-treatments revealed that screening and shredding is more efficient than extrusion for reducing emissions of pollutants such as PCDDs and PCDFs in combustion. The evaluation of the combustion behaviour of MSW-based fuels showed a three-stage oxidative decomposition, and an acceleration of the decomposition of the MSW compared to the lignocellulosic materials, which may be attributed to the presence of food waste and plastics in the MSW. Combustion tests of fuel blends containing WW and MSW-based fuels with different food waste content suggested that WW, not food waste content, is the key factor for the formation of PCDDs, PCDFs, and polychlorinated biphenyls (PCB), benzenes (PCBzs) and phenols (PCPhs). Torrefaction may be a suitable technology for improving the properties of waste as a fuel e.g. due to its low PCDD and PCDF emissions. / Förbränning med energiåtervinning är det huvudsakliga sättet att ta hand om avfall som inte kan återanvändas eller återvinnas. Det är en väletablerad energikälla i Europa och särskilt i Sverige där 2,2 miljoner ton avfall, däribland inhemskt och importerat hushållsavfall och returträ, förbrändes under 2015. På grund av den heterogena sammansättningen hos hushållsavfall och returträ är förbränning av dessa material i anläggningar med energiåtervinning (så kallade WtE-anläggningar) förknippade med en del driftsrelaterade utmaningar. Det kan även ge upphov till miljöfarliga utsläpp, som dock kan reduceras genom förbehandling av avfallet. I denna avhandling har variationer i sammansättningen hos hushållsavfall och returträ som förbränns i WtE-anläggningar undersökts. Effekten av bränslemixens sammansättning och ev förbehandling på bränslets förbränningsegenskaper samt bildning av långlivade organiska föroreningar (så kallade POPar) såsom polyklorerade dibenso-p-dioxiner och polyklorerade dibensofuraner vid förbränning har utvärderats. Det övergripande målet är att bidra till en djupare förståelse av hur valet av förbehandlingsteknik för avfall kan bidra till att minska skadliga utsläpp till luft när avfallsbränslen förbränns i WtE-anläggningar. Denna avhandling beskriver den stora variabiliteten av metall- och materialföroreningar i inhemskt och importerat returträ och föreslår förbehandlingstekniker för att producera bränslen med låg potential att generera föroreningar. En jämförelse av mekaniska förbehandlingstekniker visade att mekanisk sönderdelning och separering (krossning och siktning) är mer effektivt än s.k. högtrycks-pressning för att minska utsläppen av föroreningar som dioxiner och furaner vid förbränning. Utvärderingen av bränslemixar innehållande hushållsavfall uppvisade en oxidativ nedbrytning i tre steg vid förbränning, och en accelererad nedbrytning av avfallsmaterialet jämfört med vedmaterialet i bränslet, troligen som effekt av innehållet av matavfall och plast i hushållsavfallet. Förbränningsförsök med bränsleblandningar av returträ och hushållsavfall med olika innehåll av matavfall visade att mängden returträ, och inte mängden matavfall, är den viktigaste faktorn för bildning av dioxiner, furaner, klorbifenyler, klorbensener, och klorfenoler. Torrefiering kan vara en lämplig teknik för att förbättra avfallets bränsleegenskaper, t.ex. på grund av dess låga emissioner.

O interesse por novas fontes renováveis de energia e, alem de uma tendência, uma necessidade da sociedade atual. Neste contexto, o uso da biomassa para fins energéticos apresenta-se de forma promissora, pois reúne atributos suficientes para contribuir com a diversificação da matriz energética local/nacional. No campo das possibilidades advindas da biomassa, se apresentam os resíduos de madeira de origem urbana, que poderiam contribuir, por exemplo, para aliviar a pressão sobre as florestas. Contudo, o uso destes resíduos na forma em que se encontram pode ser dificultado devido, entre outros, a presença de contaminantes e a alta heterogeneidade destes materiais. Neste sentido, o objetivo geral deste trabalho foi levantar os principais contaminantes presentes em resíduos de madeira de origem urbana, bem como realizar a caracterização energética desta madeira. O material analisado foi coletado em uma usina de reciclagem instalada no município de Piracicaba- SP. Os métodos e as analises descritos foram baseados em normas brasileiras, internacionais e em referencias da literatura. Os resultados são apresentados nos capítulos dois, três, quatro e cinco deste trabalho. / Interest in new renewable sources of energy is, beyond a global trend, a necessity of modern society. In this context, the use of biomass for energy purposes is presented as promising, as it gathers enough attributes to contribute to diversification of the local / national energy matrix. In the list of possibilities arising from biomass, present wood residues of urban origin, which could contribute, for example, to ease the pressure on forests. However, the use of this waste in the form in which they were discarded by society, without any prior treatment can be difficult, especially due to the presence of contaminants and also due to the high heterogeneity of these wastes. In this sense, the aim of this study was to identify the main contaminants in wood waste from urban as well as perform energy characterization of the material. The waste analyzed were collected in a recycling plant in the city of Piracicaba, SP. The methods used and the analyzes were based on Brazilian standards, international and literature references. The results are presented in the chapters two, three, four, five of this work.

O interesse por novas fontes renováveis de energia e, alem de uma tendência, uma necessidade da sociedade atual. Neste contexto, o uso da biomassa para fins energéticos apresenta-se de forma promissora, pois reúne atributos suficientes para contribuir com a diversificação da matriz energética local/nacional. No campo das possibilidades advindas da biomassa, se apresentam os resíduos de madeira de origem urbana, que poderiam contribuir, por exemplo, para aliviar a pressão sobre as florestas. Contudo, o uso destes resíduos na forma em que se encontram pode ser dificultado devido, entre outros, a presença de contaminantes e a alta heterogeneidade destes materiais. Neste sentido, o objetivo geral deste trabalho foi levantar os principais contaminantes presentes em resíduos de madeira de origem urbana, bem como realizar a caracterização energética desta madeira. O material analisado foi coletado em uma usina de reciclagem instalada no município de Piracicaba- SP. Os métodos e as analises descritos foram baseados em normas brasileiras, internacionais e em referencias da literatura. Os resultados são apresentados nos capítulos dois, três, quatro e cinco deste trabalho. / Interest in new renewable sources of energy is, beyond a global trend, a necessity of modern society. In this context, the use of biomass for energy purposes is presented as promising, as it gathers enough attributes to contribute to diversification of the local / national energy matrix. In the list of possibilities arising from biomass, present wood residues of urban origin, which could contribute, for example, to ease the pressure on forests. However, the use of this waste in the form in which they were discarded by society, without any prior treatment can be difficult, especially due to the presence of contaminants and also due to the high heterogeneity of these wastes. In this sense, the aim of this study was to identify the main contaminants in wood waste from urban as well as perform energy characterization of the material. The waste analyzed were collected in a recycling plant in the city of Piracicaba, SP. The methods used and the analyzes were based on Brazilian standards, international and literature references. The results are presented in the chapters two, three, four, five of this work.

The aim of the thesis is a design of a grate steam boiler with capacity of 35 t/h and output steam parameters with temperature 430 °C and pressure 4,1 MPa. The first part of the thesis deals with stoichiometric calculations and boiler efficiency. The theses mainly focuses on the heat transfer calculation and the geometric design of individual heat transfer surfaces. The specifics of fuel are taken into consideration. The drawing of the basic boiler scheme is a part of the thesis.

The master´s thesis deals with steam boiler design that burns contaminated wood with output 55 tons of steam per hour, steam pressure 4,2 MPa and temperature 423 °C. First two chapters focuses on stoichiometry and calculation of heat losses and boiler efficiency. Great part of thesis constitutes of thermal and dimensional calculations of every heat transfer surface. Some specific boiler parts are described considering special fuel properties. Final chapters contain pressure losses calculation of flue gas and heated medium for pumps and fans design. Drawing is also part of the work which is included as an attachment.