Fuel supply chain analysis of Turkey

In spite of its natural sources, Turkey depends on other countries in terms of energy production, and a transfer from conventional fossil sources to sustainable energy sources is strongly necessary. Among the sustainable energy sources, biomass is the subject of this study. The characteristics, logistic aspects, environmental aspects, economical, legal and technical aspects are investigated in order to show that the possible biomass co-firing is very important for the construction of economic, sustainable and environmentally friendly energy systems

Materiais para caldeiras e turbinas de centrais termoeléctricas avançadas

reduzir a emissão de CO2 para a atmosfera, a qual contribui grandemente para o aquecimento global. Nas centrais termoeléctricas, o aumento da eficiência energética conduz à redução da emissão de CO2. Assim, encontram-se actualmente em desenvolvimento unidades produtoras de energia através da queima de combustíveis fósseis, com elevada eficiência energética, com funcionamento a uma pressão do vapor de cerca de 35 MPa e a uma temperatura do vapor até cerca de 760ºC, com custos de produção de energia relativamente baixos e com poluição inferior. As tecnologias avançadas podem ainda proporcionar captura e sequestro de CO2. Contudo, estas tecnologias avançadas aumentam a severidade das condições de funcionamento, requerendo melhoria das características de resistência à corrosão e mecânicas dos materiais em que são fabricados os equipamentos. Numerosos estudos efectuados em aços e ligas resistentes ao calor têm levado a grande aumento das propriedades dos aços com 9-12 % Cr, dos aços austeníticos e das ligas de níquel. Neste artigo referem-se os principais materiais desenvolvidos ou em desenvolvimento para caldeiras e turbinas de centrais termoeléctricas funcionando em condições ultra-supercríticas e ultra-supercríticas avançadas

Materiais e energia, conversão termoquímica de combustíveis

Os combustíveis fósseis são responsáveis pelo fornecimento de três quartos da energia consumida no mundo. Importantes desenvolvimentos têm sido e continuam a ser feitos na área da conversão termoquímica de combustíveis visando a produção e fornecimento seguro de energia a preços acessíveis e com reduzido teor de emissões para a atmosfera. Assim, a procura de materiais capazes de serem usados a temperaturas cada vez mais elevadas tem crescido continuamente nas últimas décadas. Neste trabalho é efectuada uma síntese sobre o estado da arte dos materiais mais usados no fabrico de equipamento destinado à produção de energia através de tecnologias associadas aos processos de conversão termoquímica (combustão, nomeadamente em leito fluidizado, gaseificação, liquefacção e pirólise) de diversos combustíveis. Para determinação da adequabilidade dos materiais no que diz respeito quer à sua resistência à corrosão, quer às suas propriedades termomecânicas, é feita a correlação das características dos vários processos e das características de agressividade/corrosividade dos combustíveis (fósseis, biocombustíveis e resíduos) com as características dos materiais de construção de equipamento a usar

Materiais e energia: conversão termoquímica de combustíveis

Os combustíveis fósseis são responsáveis pelo fornecimento de três quartos da energia consumida no mundo. Importantes desenvolvimentos têm sido e continuam a ser feitos na área da conversão termoquímica de combustíveis visando a produção e fornecimento seguro de energia a preços acessíveis e com reduzido teor de emissões para a atmosfera. Assim, a procura de materiais capazes de serem usados a temperaturas cada vez mais elevadas tem crescido continuamente nas últimas décadas. Neste trabalho é efectuada uma síntese sobre o estado da arte dos materiais mais usados no fabrico de equipamento destinado à produção de energia através de tecnologias associadas aos processos de conversão termoquímica (combustão, nomeadamente em leito fluidizado, gaseificação, liquefacção e pirólise) de diversos combustíveis. Para determinação da adequabilidade dos materiais no que diz respeito quer à sua resistência à corrosão, quer às suas propriedades termomecânicas, é feita a correlação das características dos vários processos e das características de agressividade/corrosividade dos combustíveis (fósseis, biocombustíveis e resíduos) com as características dos materiais de construção de equipamento a usar

PCDD/F formation in the co-combustion with biomass and coal: the influence of chlorine, copper, calcium and sulphur

The reduction of CO2 emissions is the primary goal of partially replacing coal with Renewable Energy Sources (RES) of biomass origin, accompanied with the reduction of emissions of other pollutants. At the same time, there are advantages in mixing this particular resource - solid biomass - with coal, due to positive synergies arising from the introduction of different amounts of volatile matter, ash, sulphur, calcium, chlorine, and heavy metals. The option for the co-combustion with biomass with coal using fluidised bed technology could contribute to the fulfilment of the EU objectives in terms of environmental protection and sustainable energy production

Use of chemical fractionation to understand partitioning of biomass ash constituents during co-firing in fluidized bed combustion

Three species of biomass origin (straw pellets, olive cake and wood pellets) and two coals from different countries (Coal Polish and Coal Colombian) have been studied to understand the fate of their ash forming matter during the combustion process and to investigate the influence of co-firing biomass with coal. Three different approaches to investigate the ash behaviour were employed: (1) chemical fractionation analysis to evaluate the association/reactivity of ash forming elements in the fuels as a prediction tool, (2) establishment of elements partitioning in ash streams produced in the combustion and co-combustion trials, and (3) evaluation of enrichment factors of elements in the ash streams. The chemical fractionation analysis was applied to all fuels used to evaluate how the association/reactivity of elements making up ash may influence their behaviour during combustion. Combustion tests were carried out on a pilot scale fluidized bed combustor (FBC). Four ash streams were obtained at different locations. The uncertainty of measurements was estimated allowing a critical evaluation of mass balances over the combustion system and the partitioning of elements in the ash streams. The enrichment factors of elements in the several ash streams were estimated, incorporating uncertainties associated with analytical measurements. Results obtained showed that for FBC the relation between the chemical fractionation and the experimental partitioning is strongly affected by elutriation of particles. The element enrichment factor estimated for each ash stream, using Al as a reference element, revealed better correlations with the elements reactivity obtained by chemical fractionation because it overcomes particles elutriation effects. Nevertheless, it was observed that the reactivity estimated by chemical fractionation could not be solely interpreted as tendency of the elements to volatilize on FBC system, as reaction in bed zone of boiler may also occur retaining reactive elements

Toxicity of Ashes Produced During the Combustion and Co-combustion of Coal and Meat and Bone Meal in a Fluidized- Bed Reactor

The replacement of fossil fuels by renewable fuels can contribute to improve the environmental performance of the power production and to move forward in the sustainability way. The experience has shown that the availability of alternative fuels can be an obstacle for its extensive use for energy production, since biomass is not always available. The use of non-hazardous wastes may be a good alternative to biomass, mainly if they are economically unattractive for recycling or if they present a high cost for land-filling. The co-firing of non-hazardous wastes with coal is, therefore, a subject of great interest for the sustainability of energy production and the reduction of the emissions of fossil greenhouse gases. The use of these wastes for energy is promising if they combine well with other fuels during the conversion process for energy production and have no negative effect on the combustion system, on the ash quality and on the gaseous emissions

Uncertainty estimation to evaluate mass balances on a combustion system

Mass balances of ash and potassium for a fluidized bed combustor were performed incorporating measurement uncertainties. The total output mass of ash or a chemical element should be equal to the mass in the input fuel; however, this is not often achieved. A realistic estimation of recovery uncertainty can support the reliability of a mass balance. Estimation of uncertainty helps to establish a reliable evaluation of the recovery ratio of ash mass and elemental mass. This may clarify whether any apparent lack in closing the mass balance can be attributed to uncertainties. The evaluation of measurement uncertainty for different matrices, namely coal, biomass, sand and ashes from different streams was based on internal quality control data and external quality control data, namely analysis of samples from proficiency tests or use of a certified reference material. The evaluation of intermediate precision and trueness allowed the estimation of measurement uncertainty. Due to the different physic and chemical characteristics of the studied matrices, the uncertainty of precision was evaluated using R-charts of data obtained from the analysis of duplicates for the majority of samples. This allowed evaluating sample heterogeneity effects. The instrumental acceptance criterion was also considered and included in the combined uncertainty. The trueness was evaluated using data from several proficiency tests and from analysis of a certified reference material or sample spiking. Statistically significant bias was included