Ksepko E.,Institute for Chemical Processing of Coal
International Journal of Hydrogen Energy | Year: 2014
This paper contains the results of research on chemical-looping combustion (CLC). CLC is one of the most promising combustion technologies and has the main advantage of producing a concentrated CO2 stream, which is obtained after water condensation and without any energy penalty for CO2 separation. The objective of this work was to study the chemical-looping reaction performance of novel perovskite-type oxygen carriers. The Sr(Mn 1-xNix)O3 family was tested for its suitability as an oxygen carrier in hydrogen (syngas component) combustion for power generation. Sr(Mn1-xNix)O3 perovskite-type oxides with x = 0, 0.2, 0.5, 0.8, and 1.0 were prepared. Thermogravimetric measurements were performed to investigate the oxidation/reduction of the obtained materials. Reactivity tests were performed under isothermal conditions during multiple redox cycles using a thermogravimetric analyzer (TGA). For the reduction reaction, 3% H2 in Ar was used, and air was used for the oxidation cycle. The effect of reaction temperature (600-800 °C) and the number of reducing/oxidizing cycles (up to 5 cycles) on the performance of the oxygen-carrier samples developed in this study were evaluated. The stability, oxygen transport capacity, and reaction rates were analyzed on the basis of thermogravimetric TG results. The Sr(Mn1-xNix)O 3 oxides showed stable chemical-looping performance with rapid changes in their oxygen content (2-3 min) while maintaining their chemical properties. The cyclic redox reaction revealed that Sr(Mn1-xNi x)O3 exhibits excellent structural stability and provides a continuous oxygen supply during redox reactions. Good oxygen capacity was maintained during the cycling hydrogen combustion tests. These new perovskite-type materials were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements and by surface area (BET), particle size distribution (PSD) and melting behavior analyses. The Sr(Mn 1-xNix)O3 oxides exhibited high melting temperatures and small surface areas. The promising results obtained from chemical-looping combustion experiments indicate that the Sr(Mn 1-xNix)O3 oxides are potentially useful oxygen carriers for chemical-looping combustion processes where hydrogen is one of the fuel components. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Sajdak M.,Institute for Chemical Processing of Coal
Central European Journal of Chemistry | Year: 2013
The aim of this work was to implement a chemometric analysis to detect the relationships between the analysed variables in samples of solid fuels. Efforts are being made to apply chemometrics methods in environmental issues by developing methods for the rapid assessment of solid fuels and their compliance with the required emission characteristics regulations. In the present investigation, two clustering techniques - hierarchical clustering analysis (HCA) and principal components analysis (PCA) - are used to obtain the linkage between solid fuel properties and the type of sample. These analyses allowed us to detect the relationships between the studied parameters of the investigated solid fuels. Furthermore, the usefulness of chemometrics methods for identification of the origin of biofuels is shown. These methods will enable control of the degree of contamination. © 2013 Versita Warsaw and Springer-Verlag Wien.
Lasek J.,National Taiwan University |
Lasek J.,Institute for Chemical Processing of Coal |
Yu Y.-H.,National Taiwan University |
Wu J.C.S.,National Taiwan University
Journal of Photochemistry and Photobiology C: Photochemistry Reviews | Year: 2013
The photocatalytic methods for nitrogen oxides removal were recently very intense areas of scientific research. Photo-deNOx processes offer interesting ways for abatement of these harmful gases. This review describes several methods for removing NO by photocatalytic reactions. These methods can be classified into three major groups: photo selective catalytic reduction (photo-SCR), photo-oxidation and photo-decomposition. The application of photocatalysts and photo-processes for NOx abatement in real-scale cases are presented. The fast-growing development of these methods is revealed by the large number of issued patents in photo-deNOx applications. The mechanism of NO creation and the traditional methods (primary and secondary) of NOx removal are summarized and discussed. A cooperative system that combines the traditional (thermal) process and a photo-process is then proposed for improving NOx removal efficiency. © 2012 Elsevier B.V.
Al-Mansour F.,Jozef Stefan Institute |
Zuwala J.,Institute for Chemical Processing of Coal
Biomass and Bioenergy | Year: 2010
Reduction of the emissions of greenhouses gases, increasing the share of renewable energy sources (RES) in the energy balance, increasing electricity production from renewable energy sources and decreasing energy dependency represent the main goals of all current strategies in Europe. Biomass co-firing in large coal-based thermal power plants provides a considerable opportunity to increase the share of RES in the primary energy balance and the share of electricity from RES in gross electricity consumption in a country. Biomass-coal co-firing means reducing CO2 and SO2, emissions and it may also reduce NOx emissions, and also represents a near-term, low-risk, low-cost and sustainable energy development. Biomass-coal co-firing is the most effective measure to reduce CO2 emissions, because it substitutes coal, which has the most intensive CO2 emissions per kWh electricity production, by biomass, with a zero net emission of CO2. Biomass co-firing experience worldwide are reviewed in this paper. Biomass co-firing has been successfully demonstrated in over 150 installations worldwide for most combinations of fuels and boiler types in the range of 50-700 MWe, although a number of very small plants have also been involved. More than a hundred of these have been in Europe. A key indicator for the assessment of biomass co-firing is intrduced and used to evaluate all available biomass co-firing technologies. © 2010 Elsevier Ltd. All rights reserved.
Ksepko E.,Institute for Chemical Processing of Coal
Journal of Thermal Analysis and Calorimetry | Year: 2014
In this paper, novel low-cost oxygen carriers containing Fe 2O3 are evaluated for use in chemical looping combustion. Sewage sludge ashes and reference samples were prepared and used in cyclic reduction and oxidation experiments in a thermogravimetric analyzer (TG). A gaseous (3 % H2) fuel and a solid fuel (hard coal) were tested. Three-cycle CLC tests were carried out in the 600-800 °C temperature range and long-term testing was performed at 950 °C. A reactivity study showed that the natural sewage sludge ash sample was stable during the cycling TG tests when hydrogen was used as a fuel at all of the temperatures investigated. Strong temperature effects on the oxygen transport capacity were observed. An onecycle test at 900 °C showed also that the sewage sludge ash successfully reacted with coal. The oxygen released was fully used for coal combustion, with appreciable reaction rate at temperature of ~750-800 °C, that is significantly lower than that obtained for pure Fe2O3-based oxygen carrier. The oxidation reaction was much faster than the reduction reaction. Moreover, the sewage sludge ash showed a low tendency toward agglomeration in the cyclic test, which was superior to the behavior of synthetic materials. The sewage sludge ash exhibited also high mechanical strength, an attrition index of 1 % and a hightemperature resistance of 1,170 °C in a reducing atmosphere. We conclude that sewage sludge ash can be effectively used as a low-cost, valuable oxygen carrier in practical application in chemical looping combustion technology for power generation. © Akadémiai Kiadó, Budapest, Hungary 2014.