The thesis is focused on the possibility of using secondary energy resources as an additive to concrete to improve some of its resulting properties. The theoretical part is devoted to the problems of shrinkage and prominence hydration process during hydration of the concrete. This section also contains the results of research work from domestic and foreign sources of high temperature fly ash and fluidized bed combustion fly ash use and their using in concrete. The practical part verifies the possibility of using these materials and their combination as an additive to concrete with impact on the physical and mechanical properties.

Secondary energy products are used in the construction industry for a long time. More strict environmental limits for emissions to air have created new technologies combustion of materials in thermal power plants. In this way combustion are produced a new secondary energy products. It is an attempt to find of suitable use for these products. Their use will have ecological impact on the environment and it will allow prepare of new compositions of higher utility properties. The aim of this study was to develop a new mixture, using the new secondary energy products, for production concrete with high utility properties.

This thesis analyses two strategies for decreasing anthropogenic carbon dioxide (CO2) emissions: to capture and store CO2, and to increase the use of biomass. First, two concepts for CO2 capture with low capture penalties are evaluated. The concepts are an integrated gasification combined cycle where the oxygen is supplied by a membrane reactor, and a hybrid cycle where the CO2 is captured at elevated pressure. Although the cycles have comparatively high efficiencies and low penalties, they illustrate the inevitable fact that capturing CO2 will always induce significant efficiency penalties. Other strategies are also needed if CO2 emissions are to be forcefully decreased. An alternative is increased use of biomass, which partially could be used for production of motor fuels (biofuels). This work examines arguments for directing biomass to the transport sector, analyses how biofuels (and also some other means) may be used to reduce CO2 emissions and increase security of motor fuel supply. The thesis also explores the possibility of reducing CO2 emissions by comparatively easy and cost-efficient CO2 capture from concentrated CO2 streams available in some types of biofuel plants. Many conclusions of the thesis could be associated with either of three meanings of the word sense: First, there is reason in biofuel production – since it e.g. reduces oil dependence. From a climate change mitigation perspective, however, motor fuel production is often a CO2-inefficient use of biomass, but the thesis explores how biofuels’ climate change mitigation effects may be increased by introducing low-cost CO2 capture. Second, the Swedish promotion of biofuels appears to have been governed more by a feeling for attaining other goals than striving for curbing climate change. Third, it seems to have been the prevalent opinion among politicians that the advantages of biofuels – among them their climate change mitigation benefits – are far greater than the disadvantages and that they should be promoted. Another conclusion of the thesis is that biofuels alone are not enough to drastically decrease transport CO2 emissions; a variety of measures are needed such as fuels from renewable electricity and improvements of vehicle fuel economy. / QC 20100823

Bibliography: 208-218. / 339 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1989

Abstract Energy production in combustion power plants is a significant source of anthropogenic carbon dioxide emissions. The targets of international climate agreements call for utilizing all available technologies to achieve rapid and cost-effective emission reductions. Carbon capture and storage is one of the possible technical solutions applied in combustion power plants. Circulating fluidized bed boilers have gained increasing popularity due to advantages in availability, emission control, fuel flexibility and option for using challenging fuels, and the possibility of using high-efficiency steam cycles. In the novel process of oxy-combustion, combustion air is replaced by a mixture of oxygen and recycled flue gas to facilitate the capture of carbon dioxide from the flue gas flow. Additional degrees of freedom become available for combustion control as the gas flow and composition can be controlled separately for fluidization and combustion purposes. In the research for this thesis, self-optimizing control was applied for the control structure design of a circulating fluidized bed boiler. Self-optimizing control offers a systematic tool for the early phases of control design, in which decisions have traditionally been made based on intuition, heuristics and previous experience. The self-optimizing control approach searches for controlled variables without a need for constant setpoint optimization when the process is affected by disturbances and implementation errors. Results presented in the thesis show that self-optimizing control can be applied in the control structure design of circulating fluidized bed combustion. A range of control structure alternatives were evaluated using steady-state approximations of a validated process model. For the novel oxy-combustion process, promising control structures were identified and could be dynamically demonstrated. / Tiivistelmä Energiantuotanto polttovoimalaitoksissa on merkittävä hiilidioksidipäästöjen lähde. Kansainväliset ilmastotavoitteet edellyttävät kaikkien käytettävissä olevien teknologioiden hyödyntämistä päästövähennysten aikaansaamiseksi nopeasti ja kustannustehokkaasti. Hiilidioksidin talteenotto on yksi mahdollisista teknisistä ratkaisuista polttovoimalaitoksissa. Kiertoleijukattilat ovat saavuttaneet kasvavaa suosiota etuinaan hyvä käytettävyys, tehokas päästöjen hallinta, soveltuvuus erilaisten haastavienkin polttoaineiden hyödyntämiseen ja mahdollisuus tehokkaiden höyrykiertojen käyttöön. Uudessa happipolttoprosessissa palamisilma korvataan hapen ja kierrätetyn savukaasun seoksella, mikä mahdollistaa hiilidioksidin talteenoton savukaasuista. Kiertoleijupolton säädön kannalta vapausasteet lisääntyvät, sillä leijutukseen ja polttamiseen käytettävän kaasun määrää ja koostumusta voidaan säätää erikseen. Väitöstutkimuksessa käytettiin itseoptimoivaa säätöä kiertoleijukattilan säätörakenteiden suunnitteluun. Itseoptimoiva säätö tarjoaa systemaattisen menetelmän säätösuunnittelun alkuvaiheeseen, jossa päätöksenteko on perinteisesti tehty esimerkiksi intuition, heuristiikan ja aiempien ratkaisujen perusteella. Menetelmän tavoitteena on löytää säädettävät muuttujat, joiden asetusarvot eivät vaadi jatkuvaa optimointia, vaikka prosessiin vaikuttavat erilaiset häiriöt ja mittausvirheet. Väitöstutkimuksen tulokset osoittavat, että itseoptimoiva säätö soveltuu kiertoleijupolton säätörakenteiden suunnitteluun. Erilaisten säätörakenteiden toimivuutta arvioitiin käyttäen validoidun prosessimallin tasapainotilan approksimaatioita. Uudelle happipolttoprosessille löydettiin lupaavia säätörakenteita, joiden toimintaa voitiin demonstroida myös dynaamisesti.

Orientador: Arai Augusta Bernardez Pecora / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-13T23:51:53Z (GMT). No. of bitstreams: 1 Morita_EugeniodeSouza_M.pdf: 4021816 bytes, checksum: da9670c797e58d9f79ea109135e7df7d (MD5) Previous issue date: 2009 / Resumo: O objetivo deste trabalho é avaliar as emissões de óxidos de nitrogênio (NO + NO2) durante a combustão de carvão mineral com adição de calcário dolomítico como adsorvente em leito fluidizado circulante (LFC). As variáveis de influência estudadas foram o excesso de ar, que variou entre 18 e 32 %, e a relação molar cálcio enxofre (Ca/S) que variou entre 0 e 2. A quantificação das emissões de NOx foi realizada em condições de regime estacionário através da técnica de detecção por infravermelho não dispersivo (NDIR). Perfis de temperatura e pressão foram medidos durante a realização dos experimentos. A combustão foi mantida a uma temperatura média do riser de 840 ºC e velocidade superficial do gás próxima de 9 m.s-1. Utilizou-se um Delineamento Composto Central Rotacional (DCCR) para o planejamento dos experimentos mediante determinação das variáveis de influência e seus limites de operação. Um total de treze experimentos foram realizados, sendo onze deles relativos ao planejamento experimental. A influência do parâmetro relação molar Ca/S foi mais significativa quando comparada à influência do excesso de ar. O aumento da razão Ca/S provocou acréscimo nas emissões de NOx, enquanto a redução do excesso de ar provocou a diminuição das emissões. Os resultados obtidos nesta pesquisa apontam para uma região de otimização, buscando-se a minimização das emissões de NOx que pode ser alcançada pela utilização de valores baixos de excesso de ar (18 %) e relação Ca/S de 0,6, uma vez que para relações maiores, a emissão de SO2 foi praticamente nula, destacando o elevado poder de remoção do enxofre por este calcário. / Abstract: This work reports an experimental study concerning NOx emissions from brazilian coal combustion with limestone addition in circulating fluidized bed as a function of operational parameters excess air (18 to 32 %) and Ca/S molar ratio (0 to 2). The NOx concentration was achieved at steady state operation through a non-dispersive infrared (NDIR) detection technique. Profiles of temperature and pressure were measured. Bed temperature around 840 ºC and superficial gas velocity around 9 m.s-1 were conditions maintained at the experiments. Central Composite Rotational Design has been used for planning the experiments according to the knowledge of influence variables on combustion process and its operational limits. A total of thirteen experiments were carried out. The influence of Ca/S molar ratio on NOx emissions was greater than air excess influence. Increasing Ca/S molar ratio it was observed tha NOx emissions also rise, meanwhile decreasing air excess factor leds a reduction on NOx emissions. Results pointed to a optimizing area, seeking to minimize NOx concentrations that can be achieved with low air excess (18 %) and Ca/S molar ratio of 0.6, since for larger ratios, the SOx emissions was insignificant, highlighting the limestone's high efficiency to sulfur capture. / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

The aim of this master thesis is study of possibilities of processing energy by-products, especially coal fly ash and fluidized bed ash, by hydrothermal treatment. Thanks to hydrothermal conditions and proper alkali activation of ashes we can obtain zeolites. Zeolites are microporous crystalline aluminosilicates which are use in many industrial sectors as catalysts, adsorbents and very good ion exchangers. The results of hydrothermal synthesis are influenced by many variable factors. This thesis mainly focused on influence of chosen alkali activator and the concentration of the activator together with a temperature of hydrothermal process. Other factor that is studied is choice of starting materials and solution/ash ratio. Phase composition of prepared samples was characterized by XRD and scanning electron microscopy (SEM). Also cation exchange capacity of prepared samples was determined.

The topic of this work is the monitoring of the effect of zinc on the hydration process in Portland mixed cement (specifically with the addition of finely ground granulated blast-furnace slag, high temperature fly ash and fluidized bed combustion filter ash). How much zinc and at what time it remains in the pore solution during hydration. Activation energy of a mixture of cement with zinc in the form of soluble salts (Zn(NO3)2.6H2O and ZnCl2) and insoluble oxide (ZnO) by isothermal calorimetry was also investigated. The XRF method has shown composition during hydration. The zinc retardation effect was investigated by isothermal calorimetry and activation energy was calculated using this method. The XRF and ICP-OES methods were used to measure the zinc content of the pore solution. And the amount of portlandite was monitored by the DTA and XRF method.

The theme of this work is to monitor the effect of zinc on the properties of blended Portland cements. Zinc was tested in the form of two-soluble salts: Zn(NO3)22 H2O and ZnCl2 and a very slightly soluble compound ZnO. Blended cements were prepared by partial replacement with finely ground granulated blast furnace slag, high-temperature and fluidized bed combustion filter fly ash. Flow properties were studied on the prepared pastes. Impact on hydration reactions was examined by using of isothermal and isoperibolic calorimetry. Flexural and compressive strength were measured as mechanical properties of the prepared test specimens. The phase composition of the prepared composites and incorporation of zinc ions in the cement matrix via leaching tests and FTIR analyzes were also studied. Microstructure development of cement samples was tested by SEM analysis with EDS. Influence on ecotoxicity was also measured.

Autoclaved aerated concrete is long-time ecological building material with usefull properties. There needs to be done research of its mineralogical compound for reengineering the production. The main mineral compound of AAC is tobermorite, it increases its mechanical properties. In the presence study, we examine the usage of nature and artificial silicious materials. Also, we investigate the influence of sulfate and alumina admixtures, as well as fluidized bed combustion ash, which can be used as the lime and gypsum replacement. Closure of the study is design of the optimal raw material composition, also hydrothermal treatment of autoclaved aerated concrete. In relation to its mechanical properties, mineralogical composition and cost.