Pyrolysis and combustion behaviour of various fuels in oxygen-enriched air and CO2 atmospheres

Yüzbaşı, Nur Sena
Oxy-fuel combustion technology, which is based on burning coal in a mixture of oxygen and recycled flue gas (RFG), is suggested as one of new promising technologies for capturing CO2 from power plants. In this thesis study, the pyrolysis and combustion behaviour of various fuels including imported coal, petroleum coke, two different types of indigenous lignites, olive residue and their blends with different proportions in air and oxy-fuel conditions were investigated by using non-isothermal thermogravimetric method (TGA) coupled with Fourier-transform infrared (FTIR) spectrometer. Pyrolysis tests were carried out in nitrogen and carbon dioxide environments, which are the main diluting gases of air and oxy-fuel environment, respectively. Pyrolysis results reveal that weight loss profiles are similar up to high temperature zone in both pyrolysis environments, indicating that CO2 behaves as an inert gas in this temperature range. However, further weight loss takes place in CO2 atmosphere v after 700oC due to CO2-char gasification reaction which is observed in pyrolysis of all fuel samples. Combustion experiments were carried out in four different atmospheres; air, oxygen-enriched air environment (30 % O2 – 70 % N2), oxy-fuel environment (21 % O2 – 79 % CO2) and oxygen-enriched oxy-fuel environment (30 % O2 – 70 % CO2). Combustion experiments show that replacing nitrogen in the gas mixture by the same concentration of CO2 does not affect the combustion process significantly but leads to slight delay (lower weight loss rate and higher burnout temperature) in combustion. Overall comparison of weight loss profiles shows that higher oxygen content in the combustion environment is the dominant factor affecting the combustion rather than the diluting gas. As O2 concentration increases profiles shift through lower temperature zone, peak and burnout temperatures decrease, weight loss rate increases and complete combustion is achieved at lower temperatures and shorter times. Pyrolysis and combustion behaviour of three different fuel blends were also investigated. Results reveal synergistic interactions in combustion tests of all blends in all combustion environments. During pyrolysis and combustion tests gaseous products CO2, CO, H2O, CH4, SO2 and COS were identified in flue gas and analyzed by using FTIR. Results indicate that higher CO and COS formation take place during pyrolysis tests due to gasification reaction in CO2 atmosphere at high temperature zone. Gaseous species evolution trends in combustion tests are found specific for each fuel. However, evolution trends slightly shift to lower temperatures in oxygen-enriched conditions.


Pyrolysis and Combustion Studies of Fossil Fuels by Thermal Analysis Methods Review
Kök, Mustafa Verşan (1995-02-01)
Instances where differential scanning calorimetry, thermogravimetry and differential thermal analysis have been applied to study the pyrolysis and combustion behaviour of fossil fuels (peat, lignite, bituminous coals, anthracite, oil shales, crude oils, lignite-oil mixtures, etc.) are reviewed. The literature survey showed that thermal methods were important not only theoretically but also from a practical point of view.
Cimino, S.; Allouis, Christophe Gerard; Mancino, G.; Nigro, R. (2014-05-01)
Hybrid catalytic combustion technology, which is a staged process comprising a preliminary catalytic partial oxidation (CPO) step followed by a homogeneous flame combustion with interstage heat removal, was tested for the first time with mixtures of methane and hydrogen. Short contact time CPO experiments were run to elucidate the effect of the progressive substitution of methane with H-2 in the fuel feed to the structured catalytic reactor, which was operated under self-sustained conditions at high tempera...
Novel investigation of pyrolysis mechanisms and kinetics for functional groups in biomass matrix
Liu, Ruijia; Liu, Guijian; Yousaf, Balal; Niu, Zhiyuan; Abbas, Qumber (2022-01-01)
Biomass, as a renewable and sustainable energy resource, can be converted into environmentally friendly and practically valuable biofuels and chemical materials via pyrolysis. However, the process optimization and pyrolysis efficiency are restricted by the limited perception of the complicated mechanisms and kinetics for biomass pyrolysis. Here, to establish an in-depth mechanism model for biomass pyrolysis, we presented a novel investigation for the thermal evolutions and pyrolysis kinetics of the function...
Investigation of alternative biomass fuels and Turkish lignites at high heating rate pyrolysis and combustion conditions
Magalhaes, Duarte; Kazanç Özerinç, Feyza; Yozgatlıgil, Ahmet; Department of Mechanical Engineering (2021-2-12)
The objective of this work was to investigate alternative Turkish fuels fortheir ignition, combustion, pyrolysis, and gasification behavior and to select alternative fuels for co-firing, co-pyrolysis, and co-gasification applications based on low and high heating rate experimental results. Agricultural biomass (olive residue, almond shell, and hazelnut shell)and Turkish lignites (Tunçbilek, and Soma) were chosen as the feedstocks. Severalexperimental rigs used such as thermogravi...
Emissions of NOx and SO2 from Coals of Various Ranks, Bagasse, and Coal-Bagasse Blends Burning in O-2/N-2 and O-2/CO2 Environments
Kazanç Özerinç, Feyza; Crnkovic, Paula Manoel; Levendis, Yiannis A. (2011-07-01)
Oxy-coal combustion is a viable technology, for new and existing coal-fired power plants, as it facilitates carbon capture and, thereby, can mitigate climate change. Pulverized coals of various ranks, biomass, and their blends were burned to assess the evolution of combustion effluent gases, such as NOx, SO2, and CO, under a variety of background gas compositions. The fuels were burned in an electrically heated laboratory drop-tube furnace in O-2/N-2 and O-2/CO2 environments with oxygen mole fractions of 20...
Citation Formats
N. S. Yüzbaşı, “Pyrolysis and combustion behaviour of various fuels in oxygen-enriched air and CO2 atmospheres,” M.S. - Master of Science, Middle East Technical University, 2011.