| 1. |
- Ajdari, Sima, 1985, et al.
(författare)
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Modeling the Nitrogen and Sulfur Chemistry in Pressurized Flue Gas Systems
- 2015
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 54:4, s. 1216-1227
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Tidskriftsartikel (refereegranskat)abstract
- A rate-based model is developed to elucidate the chemistry behind the simultaneous absorption of NOx and SOx under pressurized conditions (pressures up to 30 bar) that are applicable to the flue gases obtained from CO2 capture systems. The studied flue gas conditions are relevant to oxy-fuel and chemical-looping combustion systems. The kinetics of the reactions implemented in the model is based on a thorough review of the literature. The chemistry of nitrogen, sulfur, and N-S interactions are evaluated in detail, and the most important reaction pathways are discussed. The effects of pH, pressure, and flue-gas composition on the liquid-phase chemistry are also examined and discussed. Simulations that use existing kinetic data reveal that the pH level has a strong influence on the reaction pathway that is followed and the types of products that are formed in the liquid phase. In addition, the pressure level and the presence of NOx significantly affect the removal of SO2 from the flue gas.
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| 2. |
- Ajdari, Sima, 1985, et al.
(författare)
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Reduced Mechanism for Nitrogen and Sulfur Chemistry in Pressurized Flue Gas Systems
- 2016
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 55:19, s. 5514-5525
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Tidskriftsartikel (refereegranskat)abstract
- The gas- and liquid-phase chemistry of nitrogen and sulfur species under pressurized conditions is of high importance to the design and performance of the pressurized flue gas systems in carbon capture and storage (CCS) schemes. Yet, the available description of this chemistry is complex and difficult to apply in design studies for removal of NOx and SOx during the compression. This work proposes a reduced mechanism for engineering calculations of pressurized flue gas systems, a mechanism that is able to describe the relevant gas and liquid-phase chemistry as well as the S/N-product distribution. The reduced mechanism is derived by identifying the rate-limiting reactions using sensitivity analysis. The performance of the mechanism subsets are compared with results of a detailed mechanism. The identified rate-limiting reactions for the formation of key products form the basis for two different types of reduced mechanisms. The sets include one general reduced mechanism (valid for all pH conditions) and sets of pH-specific mechanisms. The general reduced mechanism and the pH-specific mechanisms perform satisfactorily compared to the detailed mechanism under different pH conditions. The results show that depending on the purpose of the modeling, whether it is to predict the pollutant removal (where sulfurous acid and nitrogen acids are mainly important) or capture the liquid composition, for which the N-S chemistry products are also important, different levels of simplification can be made. The number of reactions is reduced from 34 reactions (39 species) in the detailed mechanism to 12 reactions (20 species) in the general reduced mechanism and 7-8 (14-17 species) in the pH-specific mechanisms.
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| 3. |
- Alamia, Alberto, 1984, et al.
(författare)
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Well-to-wheel analysis of bio-methane via gasification, in heavy duty engines within the transport sector of the European Union
- 2016
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Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 170, s. 445-454
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Tidskriftsartikel (refereegranskat)abstract
- Bio-methane from biomass gasification (bio-methane) is expected to play a major role as a biofuel in the heavy transport sector, since the production process has reached the technical maturity required for large-scale exploitation, and the fact that bio-methane can be distributed through the compressed natural gas (CNG) and liquefied natural gas (LNG) supply chains. Assuming that the burning of biomass is climate-neutral, we compared the well-to-wheel (WtW) emissions from the use of bio-methane in heavy duty engines with those from currently used fossil alternatives: CNG, LNG, and diesel. The well-to-tank (WtT) analysis of bio-methane is based on the case study of the new GoBiGas plant in Gothenburg (Sweden), which is the largest bio-methane plant in the world currently in operation. Finally, tank-to-wheel (TtW) section compares three different state-of-the-art heavy duty gas engines: a spark-ignited (SI) gas engine; a dual fuel (DF) engine; and a high-pressure direct injection (HPDI) engine.The WtT emissions for compressed bio-methane (bio-CNG) and liquefies bio-methane (bio-LNG) were estimated at 21.5 [gCO2e/MJbioCNG] and 26.2 [gCO2e/MJbioLNG]. As compared to diesel the WtW emissions from bio-methane were reduced by 60-67%, 43-47%, and 64% when used in SI, DF, and HPDI engines, respectively. HPDI and DF are the most efficient technologies for the utilization of biomass, reducing emissions by 39 gCO2e and 33-36 gCO2e per MJ of biomass, respectively, compared with the diesel case, whereas the SI engine gave an emissions saving of 29-31 gCO2e.
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| 4. |
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| 5. |
- Almendros-Ibáñez, J. A., et al.
(författare)
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Voidage distribution around bubbles in a fluidized bed
- 2010
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Ingår i: Powder Technology. - : Elsevier BV. - 1873-328X .- 0032-5910. ; 197:1, s. 73-82
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Tidskriftsartikel (refereegranskat)abstract
- n this work, a new method for measuring void fraction distribution around endogenous bubbles in a 2D fluidized bed is presented. The technique is based on illuminating a transparent-wall 2-dimensional bed with diffuse light from the rear and recording the distribution of light that penetrates the bed. The recording is made with a high speed video-camera, which gives frames with grey level corresponding to the light penetration and from which the voidage distribution around the bubbles can be determined. In this way, voidage distribution in the region very close to the bubble contour (r/Rb less, approximate 1.2) is obtained, which was not possible in previous studies due to limitations in spatial resolution. A correlation is proposed for the voidage at the contour of the bubble, with the voidage depending on the radial position and the polar angle.In addition, the effect of the voidage distribution on the throughflow crossing the bubbles was studied and an increase of 20% was determined for the average bubble geometry of the more than 100 bubbles analysed.
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| 6. |
- Andersson, Bengt-Åke, et al.
(författare)
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Use of a conductivity heat-flow meter in fluidised-bed boilers
- 1989
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Ingår i: Transactions of the Institute of Measurement and Control. - : SAGE Publications. - 1477-0369 .- 0142-3312. ; 11:2, s. 108-112
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Tidskriftsartikel (refereegranskat)abstract
- The usefulness of a conductivity type of heat-flow meter for measurements in fluidised-bed boilers is investigated. The design and the calibration of the meter are described. Results from measurements of the local heat tranfer at the walls of fluidised-bed boilers are presented. An error analysis shows that the accuracy of the heat-flow meter is +-9%.
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| 7. |
- 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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| 8. |
- Andersson, Klas, 1977, et al.
(författare)
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Large-scale CO2 Capture – Applying the
- 2003
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Ingår i: VGB Power Tech. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Zum Abbau von Kohlendioxid-Emissionen ausIndustrieanlagen können in fossilbefeuertenkonventionellen Kraftwerken neue Verbrennungstechnikenmit nachfolgender Abscheidungund Speicherung von CO2 eingesetztwerden. Um ein solches Verfahren handelt essich bei der O2/CO2-Verbrennung, die einenherkömmlichen Verbrennungsprozess mit einertieftemperaturgestützten Luftzerlegungsanlageverbindet. Der Brennstoff wird in Sauerstoffund rezirkuliertem Rauchgas verbrannt, waseine hohe CO2-Konzentration im Rauchgasund damit eine Verringerung der Kosten derCO2-Rückhaltung zur Folge hat.Im Beitrag wird ein O2/CO2-Konzept auf großtechnischeDaten eines braunkohlebefeuerten865-MW-Referenzkraftwerks und von großenLuftabscheidungsanlagen (ASU) übertragen.Ziel der Studie ist die Beschreibung von wesentlichenKomponenten und Energieströmenbeider Prozesse sowie die Untersuchung derMöglichkeiten zur Prozessintegration. Beabsichtigtist ferner eine detaillierte Entwicklungder Rauchgasaufbereitung vor dem Transportdes separierten Kohlendioxids.Im Beitrag wird die gemeinsame Speicherungvon CO2 und SO2 vorgeschlagen. Bei Annahme,dass das Schwefeldioxid zusammen mitdem Kohlendioxid sequestriert werden kannund unter der Voraussetzung, dass das Gastrocken ist, erübrigt sich die Entschwefelungsanlage.Allerdings sind die technische Machbarkeitebenso wie die mit einer solchen Speicherungverknüpften politischen Problemenoch immer offene Fragen. Mit allen festgestelltenIntegrationsmöglichkeiten erreicht derelektrische Wirkungsgrad netto etwa 34 % – imVergleich zu 42,6 % in der Referenzanlage.
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| 9. |
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| 10. |
- Andersson, Klas, 1977, et al.
(författare)
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Process evaluation of an 865 MWe lignite fired O2/CO2 power plant
- 2006
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 47:18-19, s. 3487-3498
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Tidskriftsartikel (refereegranskat)abstract
- In order to reduce emissions of carbon dioxide from large point sources, new technologies can be used in capture plants for combustion of fossil fuel for subsequent capture and storage of CO2. One such technology is the O2/CO2 combustion process (also termed oxy-fuel combustion) that combines a conventional combustion process with a cryogenic air separation process so that the fuel is burned in oxygen and recycled flue gas, yielding a high concentration of CO2 in the flue gas, which reduces the cost for its capture. In this work, the O2/CO2 process is applied using commercial data from an 865 MWe lignite fired reference power plant and large air separation units (ASU). A detailed design of the flue gas treatment pass, integrated in the overall process layout, is proposed. The essential components and energy streams of the two processes have been investigated in order to evaluate the possibilities for process integration and to determine the net efficiency of the capture plant. The electricity generation cost and the associated avoidance cost for the capture plant have been determined and compared to the reference plant with investment costs obtained directly from industry. Although an existing reference power plant forms the basis of the work, the study is directed towards a new state of the art lignite fired O2/CO2 power plant. The boiler power of the O2/CO2 plant has been increased to keep the net output of the capture and the reference plant similar. With the integration possibilities identified, the net efficiency becomes 33.5%, which should be compared to 42.6% in the reference plant. With a lignite price of 5.2 $/MWh and an interest rate of 10%, the electricity generation cost increases from 42.1 to 64.3 $/MWh, which corresponds to a CO2 avoidance cost of 26 $/ton CO2.
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