| 1. |
- Ekvall, Thomas, 1986, et al.
(författare)
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CO-KCl-SO2 interactions in an 80 kW propane-fired flame
- 2014
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Ingår i: the proceedings of the Impacts of Fuel Quality on Power production conference, 2014. ; , s. 13-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- It is well known that combustion of biomass derived fuels may lead to problems with high-temperature corrosion (HTC). The HTC process is largely based on the release and transformation of chlorine, sulphur and alkali components during the combustion process. However, these components may also interact with other critical parts of the combustion chemistry and the present work focuses on how potassium chloride and sulphur dioxide influence the oxidation of carbon monoxide. This is investigated during combustion of propane (80 kW) applying both air and oxy-fuel combustion conditions. The experiments were carried out in Chalmers 100 kW oxy-fuel test facility in which sulphur dioxide and potassium chloride was added to the flame. The experimental results are also supported by modelling work including a detailed reaction mechanism of the related alkali-S-Cl chemistry. The results show that KCl promotes CO-oxidation in oxy-fuel combustion. However, for the experimental conditions tested in the present work, no significant effect was detected in air combustion. In addition, when adding water as well as SO2 to the flames, there were no significant effects on the measured CO concentrations in the respective flames.
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| 2. |
- Ekvall, Thomas, 1986, et al.
(författare)
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Sulphation of potassium chloride in air and oxy-fuel combustion
- 2013
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Ingår i: The Proceedings of the 38th International Technical Conference on Clean Coal & Fuel Systems, June 2-6 2013, Clearwater, Florida, USA.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- During combustion of biomass, alkali and chlorine species are released to the gas phase, species which can react to form corrosive salts that potentially may cause severe corrosion problems on heat transfer surfaces upon condensation. This corrosion process is referred to as high-temperature corrosion (HTC) and it limits steam data in biomass combustion, with corresponding limitation in thermal efficiency. The flue gas composition and also the HTC conditions can be altered by introducing a second fuel, e.g. coal for co-combustion. The flue gas composition can be altered even more drastically when applying oxy-fuel combustion where the concentration of combustion products are higher than in air firing due to the use of pure oxygen and flue gas recycling. In this work, the alkali sulphation process in different oxy-fuel and air-fuel atmospheres has been investigated by modelling the gas phase chemistry. The overall purpose is to examine the combined effects of oxy-combustion and co-combustion on the HTC process and to make a comparison with air-fired conditions. The flue gas composition in oxy-fuel combustion depends on the recirculation strategy used which in turn also influences the sulphation. According to the modelling results the degree of sulphation of gas-phase alkali metals is in general higher for oxy-fuel combustion compared to air-fuel combustion. It is concluded from the modelling results that an increased amount of sulphur and water contribute to a substantial effect on the degree of sulphation of alkali species. On the other hand, the modelling also shows that an increased content of HCl, which is present during wet recirculation, has a negative effect on the sulphation; the degree of sulphation is therefore lower in wet compared to dry recirculation. The effects of other important parameters such as sulphur-to-potassium and air-to-fuel ratios, temperature and residence time are also discussed further in the paper.
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| 3. |
- Nizzola, Giovanni, et al.
(författare)
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In-flame reduction of NOx in oxy-propane combustion at high inlet oxygen concentrations: the importance of soot-NOx interactions
- 2014
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Ingår i: Proceedings of the 38th International Technical Conference on Clean Coal & Fuel Systems, June 1-5 2014, Clearwater, Florida, USA..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Previous oxy-fuel combustion of propane performed at Chalmers University of Technology has shown possi-bilities for high NOx reduction during inlet oxygen concentrations above 35%. Such enhanced reduction has not been possible to acknowledge to only homogenous reburning effects. In this work it is investigated to what ex-tent this can be an effect of soot-NOx interactions. Soot formation has been studied by using an existing soot model. By comparing modeling results with recently published experimental data it is shown that the model is capable to predict soot formation during relevant conditions. In addition, a model for homogenous nitrogen chemistry has been used in the evaluation and sensitivity to key combustion parameters. The increased amount of soot found at high oxygen concentrations, together with higher reaction activity for gas phase species, known to be of importance for both NOx formation and soot production, support the theory that the high NOx reduction found at high oxygen concentration is a result of soot-NOx interactions.
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