| 241. |
- Kjärstad, Jan, 1956, et al.
(författare)
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Transforming the energy system in Västra Götaland and Halland – linking short term actions to long term goals
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This study analyzes pathways to meet EU, national and regional targets for CO2 emissions, energy efficiency and penetration of renewable energy in the Swedish part of the Kattegat-Skagerrak region (KASK-SE), i.e. more specifically in the counties of Västra Götaland (VGR) and Halland. Special focus is placed on four areas: The potential for energy savings in the building sector, energy savings and fuel shifting in the energy intensive industry, large-scale deployment of renewables in the electricity generation sector and greenhouse gas emission reductions in the transport sector. The energy savings are through the implementation of different energy efficiency measures.
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| 242. |
- Kjärstad, Jan, 1956, et al.
(författare)
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Transport of CO2 in the nordic region
- 2014
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 63, s. 2683-2690
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Konferensbidrag (refereegranskat)abstract
- NORDICCS is a virtual CCS networking platform aiming for increased CCS deployment in the five Nordic countries. This paper reports from work investigating options for CO2 transport infrastructure in the Nordic region. Five specific CCS cases have been selected from which capture is analyzed in detail and from which CO2 transport cost has been calculated assuming CO2 being captured only at the site itself or, assuming the selected capture site develops into a CO2-hub with CO2 from several adjacent sources. In the latter case cost has been calculated defining for what volumes pipeline transport becomes less costly than corresponding ship transport. Additionally, cost for both pipeline and ship transport has been calculated as a function of distance and volume in order to apply these calculations to derive the least costly transport mode for the fifty-five largest sources in the region with a coastal location. Also, the effect on cost for systems that will require ramp-up (i.e. transported volumes increase over time) has been calculated. Finally, an analysis of the potential for build-up of clusters in the region was performed. The work clearly shows that ship transport is the least costly transport option, not only for the five selected cases individually but also for most of the emission sources located along the coastline. The work also shows that ship transport is the least costly transport option for most of the potential clusters in the region during the ramp-up phase. An obvious but still important conclusion is that constrained storage capability and injectivity may have a profound impact on design and cost of a CO2 transport system.
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| 243. |
- Klement, Jonathan, 1994, et al.
(författare)
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Supply Chain Driven Commercialisation of Bio Energy Carbon Capture and Storage
- 2021
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Ingår i: Frontiers in Climate. - : Frontiers Media SA. - 2624-9553. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- Pulp mills, as large biogenic CO2 point sources, could adopt Bio Energy Carbon Capture and Storage (BECCS) through retrofitting carbon capture. These existing carbon sources constitute a great potential to roll out BECCS on commercial scale. Yet, despite political targets for negative emission production in Sweden, no incentive schemes were thus far enacted. While previous proposals focus on governmental compensation, the aim of this work is to set BECCS into the supply chain of a wide array of consumer products and thereby find alternative or complementary, business-driven, ways to incentivise BECCS when applied to the pulp and paper industry. In this work, we assess a “value proposition” for low-carbon products in supply chains linked to the pulp and paper industry. By projecting the costs and negative emissions related to BECCS from the pulp mill to typical consumer products, as exemplified by three case study products, we show how BECCS can substantially reduce the carbon footprint of the consumer products, while only marginally increasing their cost. Additional price premiums could shorten the payback period of the initial investment in BECCS. The developed business case presents how actors along the supply chain for pulp and paper products can collectively contribute to securing financing and to mitigating investment risks. The results challenge the private sector, i.e., the companies along the pulp-and-paper supply chain to commit considerable investments also in the case without or with too weak direct political incentives. We conclude by discussing the governance implications on corporate and public level to enable the collaborative “bottom-up” adoption of BECCS.
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| 244. |
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| 245. |
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| 246. |
- Kuehnemuth, Daniel, 1979, et al.
(författare)
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NOX reburning in oxy-fuel combustion - An experimental investigation
- 2010
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Ingår i: 27th Annual International Pittsburgh Coal Conference 2010, PCC 2010; Istanbul; Turkey; 11 October 2010. - 9781617823213 ; 1, s. 256-270
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This work investigates the reburning reduction of nitric oxide (NO) in a 100 kW propane-fired oxyfuel flame. The conducted experiments include a comprehensive parameter study: NO was injected into the recycled flue-gas, the inlet oxygen concentration was varied between 25 and 37 vol. % and the stoichiometric ratios at the burner inlet ranged from 0.7 and 1.15. The respective influence of inlet oxygen concentration and burner stoichiometry on once-through and total reduction of NO was measured. Furthermore, concentration and temperature in the furnace were mapped to identify important differences between oxy and air-fired conditions. The furnace measurements show that the peak concentration of carbon monoxide may be more than twice as high as in air-fired conditions. The formation paths of CO and its influence on the NO x chemistry are therefore discussed. The results of the parameter study show that reburning is favored by decreased burner stoichiometry. The effect of inlet oxygen concentration on once-through NO reduction is of minor importance. Changes in stoichiometry and oxygen inlet concentration are associated with changes in recycle ratio. The influence of the recycle ratio on the NO reduction is of great importance and is investigated as separate parameter.
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| 247. |
- Kuehnemuth, Daniel, 1979, et al.
(författare)
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On the carbon monoxide formation in oxy-fuel combustion-Contribution by homogenous and heterogeneous reactions
- 2014
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 25, s. 33-41
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Tidskriftsartikel (refereegranskat)abstract
- This work investigates CO formation mechanisms under oxy-fuel combustion conditions. The importance of the possible explanations for increased inflame CO concentrations in oxy-fuel flames compared to air-firing are discussed. A model based on a detailed gas-phase reaction mechanism is combined with a lignite char combustion model, including apparent surface kinetics for oxidation as well as carbon dioxide and steam gasification and implication of diffusion limitation. In agreement with other authors work, it is concluded that in gas-fired oxy-fuel flames the CO formation is promoted by a homogenous reaction between hydrogen radicals and CO2. Additionally, this work concludes that in lignite-fired oxy-fuel combustion, this gaseous reaction route is of less importance. In oxy-lignite flames, CO2 gasification is the largest contributor to the increased CO formation compared to air firing. The substitution of CO2 with steam in the oxidizer during wet oxy-fuel combustion has moderate influence on the CO2 gasification, whereas the homogenous CO formation is strongly reduced.
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| 248. |
- Kuehnemuth, Daniel, 1979, et al.
(författare)
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Reburning of Nitric Oxide in Oxy-Fuel Firing-The Influence of Combustion Conditions
- 2011
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 25:2, s. 624-631
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Tidskriftsartikel (refereegranskat)abstract
- Experiments were carried out to obtain data on the efficiency of nitric oxide (NO) reduction by reburning under oxy-fuel conditions. The work was carried out in a 100 kW test facility fired with propane. The data were analyzed by means of a combustion model, which included a detailed description of the reburning chemistry. The importance of several combustion parameters on the reburning efficiency was studied: inlet oxygen concentration, flue gas recycle ratio, temperature, and stoichiometric ratio. The inlet oxygen concentration was kept between 25 and 37 vol % and the burner stoichiometric ratio between 0.7 and 1.15. NO was injected in the oxidizer. As expected, similar to air-firing, reburning in oxy-fuel is favored by substoichiometric conditions. A decrease in combustion temperature, caused by a lowered stoichiometric ratio, is shown to be advantageous for reduction of NO under oxy-fuel conditions. The effect of inlet oxygen concentration on reburning is not significant as long as the combustion conditions are fuel-lean. However, the amount of recycled flue gas, which increases with decreasing oxygen content, significantly improves the total reduction. Instead, when the stoichiometric ratio is decreased, the recycle flow of the flue gas is reduced, which, to some extent, counteracts the otherwise positive effect of fuel-rich conditions in the flame zone in oxy-fuel conditions. Thus, during oxygen-rich combustion, the total reburning efficiency in oxy-fuel combustion is superior to once-through reburning in air-firing, but during substoichiometric conditions, the reduction in air and oxy-fuel combustion is comparable.
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| 249. |
- Köhler, Anna, 1989, et al.
(författare)
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Determination of the Apparent Viscosity of Dense Gas-Solids Emulsion by Magnetic Particle Tracking
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- When designing fluidised bed units a key to ensure efficient conversion is proper control of the mixing of the fuel in both lateral and axial directions in the bed. In order to mechanistically describe the mixing of fuel particles in a fluidised bed, there is a need to determine the apparent viscosity of the gas-solids emulsion, which determines the drag on the fuel particles. In this work the apparent viscosity of a bed of spherical glass beads and air at minimum fluidisation was determined by means of the falling sphere method. Hereto the drag of the bed on a single immersed object was obtained by measuring the velocity of a negatively buoyant tracer with magnetic particle tracking (MPT). MPT allows for highly temporally and spatially resolved trajectories (10-3 s and 10-3 m, respectively) in all 3-dimensions. The bed consisted of glass beads with a narrow size distribution (215 to 250 μm) and tracers with a size from 5 to 20 mm and densities from 4340 to 7500 kg/m3 were used. Hence, the literature, which typically covers data for velocities lying within or just above the Stoke flow regime (0.002 < Re < 2.0) could be expanded to Re numbers (53 to 152) well within the transition flow regime. The drag and apparent viscosity was compared to different fluid models and agreed well with the Newtonian model, when taking into account possible effects of the bed walls. Comparing the drag coefficient of data of free falling spheres and data of spheres falling with controlled velocities, the latter showed a dependence on the product of tracer diameter and falling velocity, dput, while the former was constant over dput. This indicates the method with controlled falling velocities to be intrusive and influencing the result of the apparent viscosity of the bed. Using the free falling sphere method this work obtained an apparent viscosity of 0.24 Pa s, which is consistent with values found in earlier literature for an emulsion of air and sand of similar size and density.
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| 250. |
- Köhler, Anna, 1989, et al.
(författare)
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Experimental characterization of axial fuel mixing in fluidized beds by magnetic particle tracking
- 2016
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A Magnetic Particle Tracking (MPT) system is applied to a bubbling fluidized bed to study how axial mixing and segregation of fuel are influenced by the fuel density and operational conditions (fluidization velocity, bed height and pressure drop across the gas distributor). The MPT system is used to determine the vertical distribution of the tracer particle in a fluid-dynamically down-scaled cold unit resembling a 0.74×0.74 m2 fluidized bed reactor operating at 800 °C. This work uses a tracer particle of 10 mm in diameter, corresponding to a fuel particle of 44 mm. Different tracer particles are applied with solids density representing biomass, biomass char and that of the average bulk. The MPT system yields a spatial accuracy in the order of 10-3 m and a time resolution of 10-3 s. For the operational range investigated, three fuel segregation regimes can be identified from the MPT measurements: 1) A flotsam regime which occurs at low fluidization velocities and for low density tracer particles, 2) A transition regime over which an increase in fluidization velocity results in that the presence of fuel particles at the bed surface decreases rapidly, and 3) A fully developed mixing regime in which the presence of tracer particle at the bed surface and the splash zone remains constant with fluidization velocity. The transition velocities between the regimes depend on bed height and density of the tracer particle.
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