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| 2. |
- Andersson, Klas, 1977, et al.
(författare)
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Flame and radiation characteristics of gas-fired O2/CO2 combustion
- 2007
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 86:5-6, s. 656-668
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an experimental study on the flame properties of O2/CO2 combustion (oxy-fuel combustion) with focus on the radiation characteristics and the burn-out behaviour. The experiments were carried out in a 100 kWth test unit which facilitates O2/CO2 combustion with real flue gas recycle. The tests comprise a reference test in air and two O2/CO2 test cases with different recycled feed gas mixture concentrations of O2 (OF 21 @ 21 vol.% O2, 79 vol.% CO2 and OF 27 @ 27 vol.% O2, 73 vol.% CO2). In-furnace gas concentration, temperature and total radiation (uni-directional) profiles are presented and discussed. The results show that the fuel burn-out is delayed for the OF 21 case compared to air-fired conditions as a consequence of reduced temperature levels. Instead, the OF 27 case results in more similar combustion behaviour compared to the reference conditions in terms of in-flame temperature and gas concentration levels, but with significantly increased flame radiation intensity. The information obtained from the radiation and temperature profiles show that the flame emissivity for the OF 21 and OF 27 cases both differ from air-fired conditions. The total emissivity and the gas emissivity of the OF 27 and the air-fired environment are discussed by means of an available model. The gas emissivity model shows that the increase in radiation intensity (up to 30%) of the OF 27 flame compared to the air flame can partly, but not solely, be explained by an increased gas emissivity. Hence, the results show that the OF 27 flame yields a higher radiative contribution from in-flame soot compared to the air-fired flame in addition to the known contribution from the elevated CO2 partial pressure.
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| 5. |
- Fleig, Daniel, 1980, et al.
(författare)
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The fate of sulphur during oxy-fuel combustion of lignite
- 2009
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 1:1, s. 383-390
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This work focuses on the sulphur chemistry in oxy-fuel combustion of lignite. Comparison is made with air-fired conditions, and the main combustion products containing sulphur (ash, SO2, SO3 and H2S) are examined by modelling and experimental data. The conversion of fuel-S to SO2 is lower in oxy-fuel than in air-fuel conditions and the SO2 concentration per unit energy supplied is therefore reduced. The modelling shows that the SO3 concentration is about four times greater than the concentration in air-firing. High SO3 and H2O contents in the oxy-fuel flue gas during wet recycling increase the acid dew-point by 20 to 30 K.
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| 6. |
- Hjärtstam, Stefan, 1978, et al.
(författare)
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Combustion characteristics of lignite-fired oxy-fuel flames
- 2009
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 88:11, s. 2216-2224
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Tidskriftsartikel (refereegranskat)abstract
- This experimental work describes the combustion characteristics of lignite-fired oxy-fuel flames, in terms of temperature distribution, gas composition (O2, CO2, CO, total hydrocarbon concentration and NO) and ignition behaviour. The aim is to evaluate the flame structure of three oxy-fuel cases (obtained by changing the flue gas recycle rate) including a comparison with an air-fired reference case. Measurements were performed in Chalmers 100 kW test unit, which facilitates oxy-fuel combustion under flue gas recycling conditions. Temperature, O2 and CO concentration profiles and images of the flames indicate that earlier ignition and more intense combustion with higher peak temperatures follow from reduction of the recycle rate during oxy-fuel operation. This is mostly due to higher O2 concentration in the feed gas, reduced cooling from the recycled flue gas, and change in flow patterns between the cases. The air case and the oxy-fuel case with the highest recycle rate were most sensitive to changes in overall stoichiometry. Despite significant differences in local CO concentration between the cases, the stack concentrations of CO are comparable. Hence, limiting CO emissions from oxy-fuel combustion is not more challenging than during air-firing. The NO emission, as shown previously, was significantly reduced by flue gas recycling.
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| 9. |
- Normann, Fredrik, 1982, et al.
(författare)
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Emission control of nitrogen oxides in the oxy-fuel process
- 2009
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Ingår i: Progress in Energy and Combustion Science. - : Elsevier BV. - 0360-1285. ; 35:5, s. 385-397
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Tidskriftsartikel (refereegranskat)abstract
- The interest in oxy-combustion as a method to capture carbon dioxide has increased drastically during recent years. The oxy-fuel process offers new process conditions and may take advantage of innovative techniques as well as of new ways to apply conventional measures for emission control. The present work reviews available techniques for controlling both the emission of nitrogen oxides (NOx) to the atmosphere and the content of NOx in the captured carbon dioxide. The results indicate that for a first generation of oxy-fuel power plants, conventional primary NOx control should be sufficient to meet today's emission regulations, if based on emission per unit of fuel supplied. However, there are several opportunities for new methods of NOx control in oxy-fuel plants, depending on future emission and storage legislation for carbon capture schemes. Improved understanding of the behaviour of nitric oxide and nitrogen dioxide during compression and condensation of carbon dioxide is needed, as well as improved knowledge on the influence of the parameters of oxy-combustion on nitrogen chemistry.
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| 10. |
- Biermann, Max, 1989, et al.
(författare)
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Capture of CO2 from Steam Reformer Flue Gases Using Monoethanolamine: Pilot Plant Validation and Process Design for Partial Capture
- 2022
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885.
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Tidskriftsartikel (refereegranskat)abstract
- Carbon dioxide (CO2) capture from a slipstream of steam reformer flue gas (18–20 vol %wet CO2) using 30 wt % aqueous monoethanolamine was performed for ∼500 h in a mobile test unit (∼120 kg CO2/h). Specific reboiler duties (SRDs) of 3.6–3.8 MJ/kg CO2 were achieved at 90% capture. The pilot data validate the modeling of off-design partial capture, that is, operation at lower CO2 capture rates (at constant gas flow) than the absorption column was designed to achieve. This paper demonstrates that off-design partial capture enables significant energy savings (SRD, cooling) relative to on-design capture. The accrued savings depend on the column design (packing height, flooding approach) and the feed CO2 concentration. Finally, a concept for stepwise deployment of carbon capture and storage in industries with high-CO2 concentration sources (e.g., steel and cement manufacturing and refining) is introduced. Thanks to its inherent full-capture-ready design, the initial energy-efficient, off-design partial capture operation can be extended to full capture over time.
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