Spelling suggestions: "subject:"waste to energy"" "subject:"taste to energy""
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Výpočtový systém pro výběr optimálního způsobu využití energie generované spalovacími procesy / Computational System for Selection of Optimal Utilization of Energy from Combustion ProcessesTouš, Michal January 2012 (has links)
PhD thesis deals with application of simulation and optimization methods in the field of waste and biomass utilization for energy purposes. Current situation in this field is described in the introductory. Following chapters deal with approaches of creating mathematical models of apparatus and processes used in the field of interest for simulation and optimization purposes. Stochastic methods, which are widely applied for real problems solution, are mentioned as well. The core of the thesis consists in proposal of systematic approach and its application for simulation and optimization model building used in the field of interest. The application is demonstrated through two case studies. The first one deals with the building of simulation model of an existing waste-to-energy plant using its operation data. The second study deals with optimization model building and its application for a problem regarding utilization of biomass in an existing energy system.
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Methods to Reduce Malodour Emission from Municipal Solid Waste Fuel / Metoder för att minska utsläpp av dålig lukt från avfallsbränsleNehaul, Nico January 2017 (has links)
Swedish power plants have in general an overcapacity which means that they must import waste from abroad. The imported fuel consists of several types of waste, but the majority originates from municipal and commercial waste. EFO is one of the leading fuel supplying and transport companies in Sweden. The company is owned by eight power plants located all around Sweden. The waste is purchased from other countries and then shipped to Sweden. During the unloading of the ship, when the cargo hatches opens, the malodourous gases will escape and be released in to the air. These malodours can travel quite far and are extremely unpleasant to people who live close by. The aim of this thesis was to suggest ways on how to prevent or reduce the emission of malodours during unloading of bales containing municipal waste. The aim of the project was to determine the causes of malodours, to identify the most common odorants in municipal waste, what properties they have, how they can be affected and how to prevent the formation of them. The problem was tackled by theoretical and practical studies. The theoretical study was a literature study and the practical study was observation at Mälarenergi combined heat and power plant. The results are presented as a number of suggestions for how to prevent or reduce the emission of malodours during unloading of bales containing municipal waste. These suggestions were divide in to the three categories Storage, Unloading and At Port. The suggestions varied from using better sorted waste to researching the possibility to use a portable tent covering the cargo ship during unloading. It was recommended that EFO should use both short- and long-term plans and also conduct further research on other ways to reduce emission of malodours.The suggestions were not tested so it cannot with certainty be determined if the suggestions will reduce or prevent emission of malodour. No laboratory tests were done on the waste. Therefore, the contents and concentrations could not be confirmed. However, it is almost certain that even if there were a slight difference it would not lead to a change of the current treatment process of the MSW. Obviously, there should have been multiple observations carried out at Mälarenergi`s power plant on various occasions and at different weather conditions. Several observations should also have been done on EFO´s other power plants to confirm that the core of the malodour emission problem is the same for all power plants. Basing suggestions on results taken from one instance might not give the correct answer to the problem. Common for malodours found in MSW is that they are formed as a product of degrading MSW. Reducing or stopping the degradation process, will prevent the formation of these compounds. This can be done either by lowering the temperature of the waste bales, altering the pH, decreasing the water content and increasing the level of Oxygen. / De svenska kraft- och värmeverken är så effektiva att det svenska bränslet inte räcker till utan man måste importera från andra länder. Bränslet består till stor del av hushållsavfall och kommersiellt avfall. EFO är ett energianskaffnings- och transportföretag som delägs av åtta svenska el- och värmeleverantörer. De förser sina ägare med bränsle till deras kraft- och värmeverk runt om i landet. Majoriteten av det inköpta bränslet kommer från utlandet och fraktas till Sverige med fartyg. Problemet för boende i närområdet är att avfallet avger dålig lukt när det lastas av från fartyg till hamn. Syftet med den här rapporten var att undersöka hur man kan förhindra eller minska utsläpp av dålig lukt vid avlastning från fartyg till hamn samt att ge förslag på metoder som kan minska luktproblematiken. Övriga mål var att fastställa vilka de mest förekommande luktämnena är, orsaken till att de bildas, vilka egenskaper de har och hur man kan förhindra att de bildas. Arbete består av en litteraturstudie tillsammans med observation gjord på Mälarenergis kraftvärmeverk. Resultaten presenterades i form av ett antal förslag på sätt att minska utsläpp av dålig lukt vid avlastning. Dessa förslag indelades i de tre områdena Lagring, Avlastning och Hamn. Förslagen var breda och sträckte sig från användning av bättre sorterat avfall till att utreda om det finns möjligheter till användning av ett portabelt tält kring fartyget under avlastning. Utöver de presenterade förslagen för minskning av luktutsläpp gavs också rekommendationen att EFO bör använda sig av både kortsiktiga och långsiktiga planer samt forska på ytterligare sätt för att minska utsläpp av dålig lukt. Förslagen har inte prövats och det kan därför inte fastställas om de reducerar och förhindrar utsläpp av dålig lukt. Det gjordes heller inte några laboratoriska analyser på avfallets innehåll därför kan det inte bestämmas om avfallet innehåller samma ämnen och koncentrationer. Sannolikt skiljer sig inte värdena så pass mycket att det skulle kräva andra typer av luktreducerande metoder. Fler observationer borde ha gjorts både på Mälarenergis anläggning och på de andra delägarnas anläggningar. Observationerna skulle då också utförts vid olika tidpunkter samt vid olika väderlek. Det är möjligt att resultatet skulle vara annorlunda om det funnits data från fler observationer. Gemensamt för ämnen som avger dålig lukt är att de uppkommer som en produkt av nedbrutet avfall. Genom att bromsa eller stoppa nedbrytningsprocessen kommer uppkomsten av dessa luktämnen förhindras. Detta kan man göra genom att förändra pH, sänka temperaturen, minska fukthalten och öka syrenivån.
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Evaluation of Overall Environmental Impacts of Alternatives for Emission Control Systems applied for Waste to Energy Process / Utvärdering av miljöpåverkan hos alternativa rökgas- och kondensatreningssystem för avfallsförbränningSundin, Camilla January 2017 (has links)
Vattenfall operates a cogeneration plant where household and industrial waste is incinerated to generate electricity and district heating. The waste incineration generates flue gases, and the energy in the hot flue gases is recovered by condensation. Both flue gases and the flue gas condensate are treated by emission control systems before being released into nature. The emission control system is planned to be updated with better technologies currently applied in Sweden. In this study, a comparison of the overall environmental impact of the current emission control system and the new system for emission control is performed. Vattenfall will perform a comparative life cycle assessment, LCA, of the two emission control systems. A part of the LCA is an inventory analysis. In this study, data required for the inventory analysis will be collected and quantified. The parameters considered are emissions to air and water, consumption of chemicals, produced solid residue, and water utilization. The objectives with the planned upgrade of the emission control system, which are evaluated in this study, are to obtain a cleaner condensate stream that can be reused in the system, to reach a higher tolerance of sulphur content in the fuel, and to reach a better reduction of emissions, for future stricter regulation. From the perspective of this study, the new system for emission control system seems to be the choice for emission control system with the least environmental impact. The results show that the reasons for upgrading the emission control system are met with the new system. The condensate is significantly cleaner with the new alternative emission control system than in the current one, the total amount of emissions decreases by 99,98 w%. The significantly smaller amount of emissions results in a condensate flow that can be reused in the system, which could save a considerable amount of raw water each year. The SO2 emissions are reduced by 99,5 w%, which show that a higher sulphur content in the fuel could be tolerated with the new emission control system. Furthermore, the total amount of emission content in the flue gas decreases with 61,9 w% with the new emission control system. The emission parameters that are deemed likely to be more strictly regulated in coming regulations, NOx and Hg, are both significantly reduced with the new emission control system. On the other hand, both the consumption of chemicals and the production of solid residue increases in the new emission control system, compared to the current one. These aspects are important drawbacks with the new system, and the environmental impact of these aspects needs to be further investigated in the planned LCA. / Vattenfall driver ett kraftvärmeverk där avfall från hushåll och industrier förbränns för att generera el och fjärrvärme. Avfallsförbränningen genererar rökgaser, och energin i rökgaserna utvinns genom kondensering. Rökgaserna och kondensatet renas från föroreningar innan de släpps ut i naturen. Systemet för rökgas- och kondensatrening ska uppdateras till nyare tekniker. I det här arbetet jämförs den totala miljöpåverkan av det nuvarande och det nya systemet för rökgas- och kondensatrening. Vattenfall kommer i framtiden att utföra en jämförande livscykelanalys av de två rökgas- och kondensatreningssystemen. En del i en livscykelanalys är en inventeringsanalys. Syftet med det här arbetet är att samla in och kvantifiera den data som behövs för inventeringsanalysen. Parametrarna som tas med i inventeringsanalysen är utsläpp till luft och vatten, kemikalieförbrukning, restprodukter samt vattenförbrukning. Målen med uppdateringen av rökgas- och kondensatreningssystemen är att erhålla ett renare kondensat som kan återanvändas i systemet, att kunna elda bränsle med en högre halt svavel och fortfarande hålla utsläppen under utsläppsgränserna, samt att få en bättre rening av föroreningar för att kunna möta framtida utsläppskrav. Målet med detta arbete är att utvärdera hur väl dessa aspekter möts i det nya systemet för rökgas- och kondensatrening. Utifrån de aspekter som utvärderats i denna studie verkar det nya systemet för rökgas- och kondensatrening ha en mindre miljöpåverkan än det nuvarande. Resultaten visar att alla målen med att uppdatera rökgas- och kondensatreningssystemet nås med det nya systemet. Kondensatet blir signifikant renare med det nya systemet jämfört med det nuvarande, den totala mängden föroreningar i kondensatet minskar med 99,98 vikts%. Det innebär att kondensatet kan återanvändas i systemet, och en betydande mängd råvatten kan sparas varje år. Utsläppen av SO2 minskar med 99,5 vikts%, vilket visar att en högre svavelhalt i bränslet skulle kunna tolereras. Vidare minskar den totala mängden föroreningar i rökgaserna med 61,9 vikts%. De föroreningsparametrar som bedöms bli mer strikt reglerade inom en snar framtid, NOx och Hg, reduceras signifikant med det nya systemet för rökgas- och kondensatrening. Däremot ökar både kemikalieförbrukningen och mängden producerad restprodukt. Ökningarna är betydande nackdelar för det nya systemet, och miljöpåverkan av detta bör undersökas vidare i den planerade livscykelanalysen.
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Co-Pyrolysis of Fruit Waste and High Density Polyethylene: Effect of Composition, Temperature and CO2 Environment on Pyrolysis ProductsNooh, Abdullah 06 1900 (has links)
Waste recycling is gaining prominence and acceptance compared to landfilling to reduce greenhouse gas emissions. Municipal solid waste (MSW), the largest source of solid waste, is primarily composed of food waste, plastics packaging and papers. Thermochemical recycling technique, such as pyrolysis, is considered as a promising alternative for producing value-added products. Pyrolysis is a process occurring in inert environments at moderate temperatures controlled by parameters such as the reaction temperature, heating rate and residence time to produce bio-oil and biochar. It is also known for its high tolerance for mixed waste stream.
In this thesis, fruit waste (FW) consisted of bananas, apples, oranges and cucumbers peels and commercial high density polyethylene (HDPE) as co-pyrolysis feedstock were investigated. Co-pyrolysis experiments were performed in a tubular furnace reactor to investigate the effect of polymer composition, temperature and CO2 atmosphere. HDPE composition was varied between 33–67% to investigate the effect of feedstock composition at 500 ˚C. A composition was fixed and then effect of temperature was assessed in the range 500–700 ˚C. Finally, in CO2 atmosphere, co-pyrolysis experiments were performed with 50% HDPE at 600 ˚C.
The collected bio-oil and biochar were thoroughly characterized via different analytical techniques. The effect of different process parameters on bio-oil was studied by gas chromatography-mass spectrometry (GC/MS), proton nuclear magnetic resonance (1H NMR) and Fourier-transform ion cyclotron resonance mass spectroscopy (FT-ICR MS). Biochar samples are analyzed using scanning electron microscopy (SEM), CHNS elemental analysis and Fourier-transform infrared (FTIR). Detailed product composition revealed that formation of hydrocarbons was promoted with increasing HDPE, while significant deoxygenation was observed with increased temperature. In addition, heavier molecules in the bio-oil were studied via FT-ICR MS. HDPE loading and CO2 atmosphere stabilized the biochar by reducing the oxygen content. The results demonstrated the potential use of HDPE as a co-feed with FW in a pyrolysis system to produce valuable products.
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Techno-economic analysis of a waste-to-energy system using innovative pyrolysis processPerrens, Hannah Sofie January 2023 (has links)
Waste management is of growing concern with increasing amount of municipal waste generation and the industry standards are becoming stricter due to climate goals and sustainable development. Waste-to-energy (WTE) systems in the form of waste incineration have been promoted as a low-carbon energy source, but nevertheless have high greenhouse gas (GHG) emissions. Pyrolysis offers an alternative way of utilizing energy which at high temperatures and in the absence of oxygen thermally decomposes material and yields products such as synthetic gas and biochar. Bodø Storstue, a development project for a new sports arena in Northern Norway, has high ambitions for sustainable development. WTE by pyrolysis has been identified as a potential step toward reducing GHG emissions. Thus, this thesis looked into the technical and economic aspects of integrating pyrolysis as a decentralized WTE system. A simulation model was built in Aspen Plus, which shows the energy and mass balance through the different modules in the system. An economic analysis was performed using MS Excel which included the levelized cost of electricity and net present value calculation. The results suggest that the electricity demand in Bodø Storstue can be met by using pyrolysis for power generation, and that carbon can be stored in biochar which reduces the emissions compared to traditional waste incineration. Future studies should include a simulation model based on tested feedstock composition which would make the simulation more representative of true conditions. The price of biochar should also be included in the economic analysis to obtain more precise conclusions about the economic conditions that impact investment decisions. / Avfallshanteringen skapar en växande oro världen över med ökande avfallsmängder och strängare bestämmelser för industrianpassning till nya klimatmål och nya strategier för hållbar utveckling. Energiutvinningssystem ur avfall i form av direkt avfallsförbränning, s.k. waste-to-energy (WTE), har marknadsförts som en miljövänlig energikälla men låga utsläpp, men har trots detta en viss del fossilbaserad kolinnehåll samt höga helhetsutsläpp av växthusgaser. Pyrolysprocesser erbjuder ett alternativt sätt att utnyttja energi genom att termiskt bryta kolväten vid höga temperaturer och i frånvaro av syre ner till enklare molekyler och således generera gasformiga produkter samt biokol. Bodø Storstue är ett utvecklingsprojekt för att bygga en ny multifunktionell idrottsarena i norra Norge, med höga ambitioner för integrerat miljötänkande. WTE genom pyrolys har identifierats som en lovande åtgärd för att minska växthusgasutsläppen från arenan. Målet härmed är således att undersöka de tekniska och ekonomiska förutsättningarna for att integrera en nyutvecklad pyrolysprocess för arenan i form av ett decentraliserat kraftvärmeverk med lokal avfallshantering där också en del biokol utvinns i fast form för att potentiellt lagras som ren kol eller för att användas till jordförbättring. Simuleringsmodeller för kraftvärmesystemet byggdes i AspenPlusTM baserade på avfallspyrolys och syntesgasförbränning, som beräknar energi- och massbalanser genom olika delmoduler. I ett nästa skede utfördes förenklade ekonomiska analyser med andra verktyg för att sammanfatta elkostnader och nettonuvärdeuträkning. Resultaten tyder på att elbehovet i Bodø Storstue kan tillgodoses genom att använda avfallspyrolys för kraft- och värmegenerering, och att kol kan lagras i form av biokol vilket minskar utsläppen jämfört med traditionell avfallsförbränning. Framtida studier bör inkludera en simuleringsmodell baserad på testad och verklighetstrogen avfallssammansättning, vilket skulle göra simuleringen mer representativ för verkliga förhållanden på arenan. Värdet på biokol bör också inkluderas i den ekonomiska analysen för att få mer precisa slutsatser om de ekonomiska förutsättningarna.
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Analysis of Acid Gas Emissions in the Combustion of the Binder Enhanced d-RDF by Ion ChromatographyJen, Jen-Fon 08 1900 (has links)
Waste-to-energy has become an attractive alternative to landfills. One concern in this development is the release of pollutants in the combustion process. The binder enhanced d-RDF pellets satisfy the requirements of environmental acceptance, chemical/biological stability, and being storeable. The acid gas emissions of combusting d-RDF pellets with sulfur-rich coal were analyzed by ion chromatography and decreased when d-RDF pellets were utilized. The results imply the possibility of using d-RDF pellets to substitute for sulfur-rich coal as fuel, and also substantiate the effectiveness of a binder, calcium hydroxide, in decreasing emissions of SOx.
In order to perform the analysis of the combustion sample, sampling and sample pretreatment methods prior to the IC analysis and the first derivative detection mode in IC are investigated as well. At least two trapping reagents are necessary for collecting acid gases: one for hydrogen halides, and the other for NOx and SOx. Factors affecting the absorption of acid gases are studied, and the strength of an oxidizing agent is the main factor affecting the collection of NOx and SOx. The absorption preference series of acid gases are determined and the absorption models of acid gases in trapping reagents are derived from the analytical results. To prevent the back-flushing of trapping reagents between impingers when leak-checking, a design for the sampling train is suggested, which can be adopted in sample collections. Several reducing agents are studied for pretreating the sample collected in alkali-permanganate media. Besides the recommendation of the hydrogen peroxide solution in EPA method, methanol and formic acid are worth considering as alternate reducing agents in the pretreatment of alkaline-permanganate media prior to IC analysis. The first derivative conductivity detection mode is developed and used in IC system. It is efficient for the detection and quantification of overlapping peaks as well as being applicable for non-overlapping peaks.
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Biomass and waste as a renewable and sustainable energy source in Vietnam / Nguồn năng lượng tái tạo bền vững từ sinh khối và rác thải sinh học ở Việt NamSchirmer, Matthias 25 August 2015 (has links) (PDF)
Due to Vietnam’s economic development its energy demand will continue to rise by 12–16% annually over the next few years. The government has realized that supply problems in the energy sector pose a significant threat to further development. Therefore, it is making concerted efforts to modernize the existing energy sector and expand the generating structure. There are ambitious expansion plans in the field of renewable energy sources, too. Owing to its very high potential, biomass could play a key role in energy production. This paper attempts to analyze the current status of biomass based energy production in Vietnam addressing variety of aspects such as biomass potential, legal framework as well as financial aspect. Section 4 contains an overview of ongoing bioenergy projects. Instead of providing a complete picture, these examples are intended to illustrate the various ways in which biomass can be used in different economic sectors. Finally existing barriers as well as action to incentivise bioenergy are discussed. / Do phát triển kinh tế, nhu cầu năng lượng của Việt Nam sẽ tiếp tục tăng 12-16% mỗi năm trong vài năm tới. Chính phủ đã nhận ra rằng vấn đề cung cấp trong lĩnh vực năng lượng gây ra một mối đe dọa đáng kể cho sự phát triển tiếp theo. Vì vậy, có các nỗ lực để hiện đại hóa ngành năng lượng hiện có và mở rộng cấu trúc sản sinh năng lượng. Cũng có những kế hoạch mở rộng đầy tham vọng trong lĩnh vự nguồn năng lượng tái tạo. Do có tiềm năng rất cao, sinh khối có thể đóng một vai trò quan trọng trong sản xuất năng lượng. Bài viết này cố gắng phân tích tình trạng hiện tại của sản xuất năng lượng sinh khối tại Việt Nam giải quyết nhiều khía cạnh nhưtiềm năng sinh khối, khuôn khổ pháp lý cũng như các khía cạnh về tài chính. Tổng quan về các dự án năng lượng sinh học đang diễn ra được trình bày trong phần 4. Thay vì cung cấp một bức tranh hoàn chỉnh, các ví dụ được dùng để minh họa cho những cách khác nhau, trong đó sinh khối có thể được sử dụng trong các lĩnh vực kinh tế khác nhau. Rào cản cuối cùng hiện tại cũng nhưhành động để khuyến khích năng lượng sinh học sẽ được thảo luận.
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Modelagem termodinâmica do processo de gaseificação : modelos de equilíbrio e semi-equilíbrioCho, João Daniel January 2017 (has links)
Orientador: Prof. Dr. Antonio Garrido Gallego / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2017. / A gaseificação é o processo de conversão termoquímica de um combustível sólido em um gasoso, produzindo o chamado gás de síntese a partir da sua combustão incompleta. O caráter energético do gás de síntese provém das parcelas metano (CH4), monóxido de carbono (CO), hidrogênio (H2) presentes, permitindo assim a utilização de resíduos sólidos para produção de um gás combustível, possibilitando sua melhor valoração em energia (waste-to-energy) com a sua utilização em ciclos de potência mais eficientes a partir de ciclos combinados e ganhos ambientais com esta conversão. Também há sua valoração para síntese de outros produtos químicos (waste-to-products) com maior valor agregado. Este trabalho tem como objetivo o estudo do processo de gaseificação, culminando na criação de modelos termodinâmicos para a descrição e predição deste fenômeno. Para isso foi realizada uma revisão bibliográfica, na qual foi feito um levantamento dos principais mecanismos descritivos do processo, principais aspectos relevantes de influência, parâmetros de análise e configurações dos principais gaseificadores utilizados atualmente. Também foram avaliados os modelos utilizados na literatura para descrição do processo, que dentre os quais escolheu-se metodologias baseadas na condição de equilíbrio químico para este trabalho. Estas metodologias utilizaram o chamado modelo estequiométrico e não-estequiométrico que se baseiam na condição supracitada. Foram identificadas deficiências quanto a previsão do gás de síntese resultante dos modelos propostos quando comparadas a dados experimentais levantados na literatura. Estas derivam principalmente da não representação de alguns fatores cinéticos, principalmente no tocante ao fenômeno de decomposição térmica no processo de gaseificação. Para contornar estas limitações, a introdução de correlações externas se mostra uma ferramenta comumente utilizada na bibliografia. Assim, foi analisada a inclusão de correlações para a previsão das parcelas de CO2, H2 e CH4, e uma função para a previsão de carbono não convertido (coque). Esta última se mostrou fundamental para uma melhor acurácia da previsão do poder calorífico do gás de síntese pelos modelos propostos. / Gasification is a thermochemical conversion process of a solid combustible into gaseous phase, producing a so-called syngas from an incomplete combustion. The energetic value of syngas is due to fractions of methane (CH4), carbon monoxide (CO) and hydrogen (H2), which enable the utilization of solid residues to produce a combustible gas (waste-to-energy). Gasification provides a better energetic valuation with its utilization on more efficient power cycles through combined cycles and environmental gains due to the conversion process. In addition, it is possible to usage utilize syngas to produce other chemical compounds (waste-to-products) with a higher commercial value. This thesis main objective is to study the gasification process, where it is proposed mathematical models to describe and predicts this phenomenon. It is conducted a bibliographical review, of which includes the descriptive mechanism and main analysis influential parameters related to this process, where commonly utilized configurations gasifier is also explored. It was also analyzed the main models observed on the literature to describe the gasification process, of which was selected methodologies based on the chemical equilibrium for this work. These methodologies utilized the stoichiometric and non-stoichiometric models that were based on the previously mentioned condition. Deficiencies related to predicted values of the composition fractions of the syngas are observed when compared to experimental data from the literature. These derive mainly from the non-representation of kinetic factors, primarily due to the pyrolysis stage of the gasification process. The usage of external correlations are useful tools to smooth these deficiencies. Therefore, an analysis of the inclusion of correlations to predict gaseous fractions of CO2, H2 and CH4 of the syngas and the fraction of non-converted carbon (char) was made. The latter proposal has shown essential to a better accuracy of the modelled calorific value of syngas.
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Thermodynamic Equilibrium Prediction of Corrosion Tendency in Fluidized-Bed Combustion of Solid WasteHosseinian, Aida January 2017 (has links)
Global warming and air pollution are two issues of greatest concerns to human life in recent years. Environmental concerns and econimal/political independency of fossil fuels have been the driving force of developing interest in renewable resources of energy for many countries. Different type of waste-derived fuels such as biomass, municipal solid waste and industrial waste are interesting energy resources for energy producing companies. There are mainly two main paths when it comes to waste-to-energy industry, which are thermal treatment of waste, as well as biochemical treatment. Thermal treatment of waste to produce energy could benefit both for hygienic consideration of waste management and avoiding waste landfill.Heat and power generation through combustion of waste or biomass has several environmental, and economical advantageous over utilization of fossil fuels. Thermal conversion of waste and biomass fuels, however, has some challenges mainly due to their chemical composition and high alkali metals (potassium and sodium) content. Combustion of these fuels usually can result in some operational challenges such as deposition, fouling, bed agglomeration and corrosion in different part of the boiler. The less reactive and non-combustible part of the fuel known as ash-forming matter has a major role in these operational challenges. Ash related problems in waste-to-energy boilers lead to lower efficiency, high maintenance costs and equipment failure. Therefore, investigating the chemical composition of fuel and ash-forming matter is essential prior to thermal conversion of waste-derived fuels. High-temperature corrosion due to formation of corrosive alkali chloride compounds during combustion is one of the main ash-related concerns in boilers.This study investigated high-temperature corrosion in circulating fluidized-bed (CFB) combustion of solid waste. Flue gas composition of solid waste combustion in the CFB boiler was analysed in two cases: combustion of the reference fuel, and combustion of the “same” fuel with a sulphur containing additive (ammonium sulphate), to decrease the corrosive alkali chlorides in the flue gas. Chemical fractionation was carried out for fuel samples to determine the reactive and less-reactive fraction of ash-forming matter. A thermodynamic equilibrium model was developed using Factsage thermochemical software, to predict the chemical composition of the flue-gas with a special focus on corrosive alkali chlorides. The modelling results were evaluated using In-situ Alkali Chloride Monitoring (IACM) results obtained during the full-scale combustion measurements.
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Catalytic Upgrading of Biogas to Fuels: Role of Reforming Temperature, Oxidation Feeds, and ContaminantsElsayed, Nada 23 January 2017 (has links)
Global energy demands are constantly increasing and fossil fuels are a finite resource. The shift towards alternative, more renewable and sustainable fuels is inevitable. Furthermore, the increased emissions of greenhouse gases have forced a pressing need to find cleaner, more environmentally friendly sources of fuel. Biomass energy is a promising alternative fuel because it offers several important advantages. It is a renewable energy form, it comes from many sources and produces biogas (CH4 and CO2). Furthermore, it can have a zero carbon footprint; this is due to the fact that the carbon produced is from the same carbon used to make the biomass. In addition, by replacing fossil fuels, the emissions of CH4 and CO2 (both greenhouse gases) is reduced. Biomass-derived syngas (H2 and CO) can be utilized as a feedstock for many important industrial processes such as methanol synthesis, ammonia synthesis and Fischer-Tropsch synthesis (FTS) to produce long chain hydrocarbon fuels.
Municipal solid waste (MSW) biomass is considered as the source of the biomass for this dissertation work. MSW accounts for 20% of man-made methane emissions making it an attractive source for utilization. However, methane reforming to synthesis gas (H2 and CO) typically occurs at temperatures higher than 600°C making it economically challenging at the smaller scale of MSW conversion processes.
This dissertation effort focused on formulating low precious metal loaded heterogeneous catalysts that can reform methane at low temperature (T<500°C) making the process more industrially viable. The effect of select contaminants (siloxanes) in the biogas on the reforming catalysts was studied through accelerated poisoning. Finally, the syngas ratio was improved by combining low temperature dry reforming with steam reforming (termed bi-reforming).
The catalyst system used for this dissertation study was comprised of 1.34wt%Ni- 1.00wt%Mg on a Ceria-Zirconia oxide support (0.6:0.4 ratio respectively). The catalysts were doped with platinum (0-0.64% by mass) and compared to palladium doped catalysts (0-0.51% by mass). The ratio chosen for the support, Ce0.6Zr0.4, was determined to be the best ratio in terms of activity and surface area by previous studies done in this group [1]. Nickel has been widely studied as methane reforming catalyst [2-6]. Alone, nickel atoms are prone to carbon deposition especially during methane decomposition, however, coupling NiO with MgO helps to reduce carbon deposition by reducing agglomeration of Ni crystallites, thereby improving catalyst lifetime [2, 7]. Furthermore, addition of small amounts of noble metals such as Pt or Pd help to drive the reduction of the catalyst to lower temperatures and enhance catalytic activity.
Different metal loadings of Pt and Pd were tested to determine the optimum catalyst that will reform methane at low temperatures, is resistant to deactivation and produces a high syngas ratio (~2:1) which is necessary for processes such as FTS. Preliminary results have shown that in general Pt is superior in this catalyst system for low temperature reforming of methane. It consistently had syngas ratios near the desired ratio compared to Pd, it did not deactivate with extended time on stream and overall had higher turnover frequencies. This catalyst system has potential to make industrial reforming of methane from biomass feedstock more economically viable.
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