Combustion characteristics of Turkish lignites at oxygen-enriched and oxy-fuel combustion conditions
| Autor: | Ramin Barzegar, Aysel T. Atimtay, Ahmet Yozgatligil |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Thermogravimetric analysis
Chemistry 020209 energy Chemical process of decomposition Analytical chemistry chemistry.chemical_element 02 engineering and technology Activation energy Combustion Oxygen Decomposition Atmosphere 020401 chemical engineering 0202 electrical engineering electronic engineering information engineering Limiting oxygen concentration 0204 chemical engineering |
| Zdroj: | Journal of the Energy Institute. 92:1440-1450 |
| ISSN: | 1743-9671 |
| DOI: | 10.1016/j.joei.2018.08.007 |
| Popis: | Combustion and oxy-fuel combustion characteristics of two Turkish lignites (Orhaneli and Soma) were investigated by Thermogravimetric Analysis (TGA) method. Experiments were carried out under oxygen-enriched air and oxy-fuel combustion conditions with 21, 30, 40% oxygen concentrations. Three heating rates of 5, 10, and 20 °C/min were considered and the isoconversional kinetic methods of FWO, KAS, and Friedman were employed to estimate activation energies. The uncertainty assessment in obtaining the activation energy values was also considered. The obtained results indicated that the combustion of volatiles at both air and oxy-fuel conditions were approximately identical. However, at air combustion conditions, the decomposition of CaCO3 took place at temperatures above 700 °C. This decomposition process was independent of the oxygen concentration and took place when the temperature reached to a certain threshold. The decomposition of CaCO3 did not accomplish in oxy-fuel conditions as far as the temperature was higher than 900 °C. Combustion in oxy-fuel conditions had higher activation energy values comparing to conventional combustion atmosphere. The activation energy values were approximately unchanged at the start of combustion regardless of oxygen concentration or combustion atmosphere at about 165 kJ/mol and 150 kJ/mol for Orhaneli and Soma lignites, respectively. The apparent activation energies were higher at elevated oxygen concentrations. The uncertainties values related to FWO method were lower than KAS and Friedman methods. The calculated average uncertainty values were found to be at the range of 5–15% for most of the cases. |
| Databáze: | OpenAIRE |
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