| 1. |
- Alamia, Alberto, 1984, et al.
(författare)
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Efficiency Comparison of Large-Scale Standalone, Centralized, and Distributed Thermochemical Biorefineries
- 2017
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Ingår i: Energy Technology. - : Wiley. - 2194-4296 .- 2194-4288. ; 5:8, s. 1435-1448
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.We present a comparison of three strategies for the introduction of new biorefineries: standalone and centralized drop-in, which are placed within a cluster of chemical industries, and distributed drop-in, which is connected to other plants by a pipeline. The aim was to quantify the efficiencies and the production ranges to support local transition to a circular economy based on biomass usage. The products considered are biomethane (standalone) and hydrogen/biomethane and sustainable town gas (centralized drop-in and distributed drop-in). The analysis is based on a flow-sheet simulation of different process designs at the 100MWbiomass scale and includes the following aspects: advanced drying systems, the coproduction of ethanol, and power-to-gas conversion by direct heating or water electrolysis. For the standalone plant, the chemical efficiency was in the range of 78-82.8% LHVa.r.50% (lower heating value of the as-received biomass with 50% wet basis moisture), with a maximum production of 72MWCH4 , and for the centralized drop-in and distributed drop-in plants, the chemical efficiency was in the range of 82.8-98.5% LHVa.r.50% with maximum production levels of 85.6MWSTG and 22.5MWH2 /51MWCH4 , respectively. It is concluded that standalone plants offer no substantial advantages over distributed drop-in or centralized drop-in plants unless methane is the desired product.
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| 2. |
- Edland, Rikard, 1990, et al.
(författare)
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Implications of Fuel Choice and Burner Settings for Combustion Efficiency and NOx Formation in PF-Fired Iron Ore Rotary Kilns
- 2017
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 31:3, s. 3253-3261
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Tidskriftsartikel (refereegranskat)abstract
- The combustion process applied in the grate-kiln process for iron ore pellet production employs air-to-fuel equivalence ratios in the range of 4-6, typically with coal as fuel and high-temperature air (>1000 degrees C) as oxidant. The NOx emissions from these units are in general significantly higher than those in other combustion systems, and the large flows of flue gases make the implementation of secondary measures for NOx control costly. Therefore, it is of importance to investigate NOx. formation under combustion conditions relevant for iron ore production, in order to control the emissions from these units. The present work examines NO formation during the combustion of four pulverized coals, as well as during cofiring with biomass in a pilot-scale kiln (580 kWfuel) based on a two-week experimental campaign. The influence of burner settings was also included in the investigation. Based on the presented experimental results and the results of previous modeling and experimental studies, we suggest that the NOx emissions are mainly the result of a high conversion of fuel-bound nitrogen (fuel-N) to NO. In particular, char-bound nitrogen (char-N) conversion appears to be higher than in conventional pulverized fuel flames, presumably due to the high levels of oxygen present in the char-burnout region. The temperatures in the kiln varied between the test cases, but thermal NO formation is estimated to be of low importance.
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| 3. |
- Hulten, A. H., et al.
(författare)
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First evaluation of a multicomponent flue gas cleaning concept using chlorine dioxide gas - Experiments on chemistry and process performance
- 2017
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 210, s. 885-891
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Tidskriftsartikel (refereegranskat)abstract
- This work has investigated a multi-pollutant flue gas cleaning concept based on oxidation using chlorine dioxide (ClO2) gas with subsequent absorption. The chlorine dioxide gas converts the relatively insoluble nitric oxide (NO) to the more soluble nitrogen dioxide (NO2). This makes a downstream wet scrubbing process feasible for simultaneous removal of sulphur oxides (SOx) and nitrogen dioxide (NO2). An experimental evaluation of the proposed process using chlorine dioxide gas has been performed on a laboratory scale. The experimental setup, designed and built by Akzo Nobel, consists of a reactor for oxidation, a flue gas condenser and a wet scrubber. The results show that ClO2 gas oxidises NO with high efficiencies under a wide range of process conditions, also in the presence of sulphur dioxide (SO2). The more ClO2 gas is added, the higher the degree of NO oxidation and the total nitrogen oxides (NOx) removal efficiency becomes. The results also show that the presence of water strongly increases the removal of SO2, which is believed to be an effect of liquid phase nitrogen-sulphur interactions. The absorption solution, sodium carbonate and sodium sulphite, is efficient in removing NOx (especially NO2) from the oxidised flue gas. The total NOx reduction at 0.6 ClO2:NO mole ratio and subsequent wet scrubbing is between 79% and 94%, depending on the process conditions used. The total SO2 reduction in the scrubber is between 97% and 100% independent of ClO2 gas addition. Furthermore, the total NOx balance shows that the major part of the NOx is converted to nitrate in the condensate liquor and as nitrite in the absorption solution. A higher ClO2 gas addition and a higher reactor temperature convert more of the NOx to nitrite in the absorption solution.
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| 4. |
- Mocholí Montañés, Rubén, 1990, et al.
(författare)
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Demonstrating load-change transient performance of a commercial-scale natural gas combined cycle power plant with post-combustion CO2 capture
- 2017
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 63, s. 158-174
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Tidskriftsartikel (refereegranskat)abstract
- The present work aims to study the transient performance of a commercial-scale natural gas combined cycle (NGCC) power plant with post-combustion CO2 capture (PCC) system via linked dynamic process simulation models. The simulations represent real-like operation of the integrated plant during load change transient events with closed-loop controllers. The focus of the study was the dynamic interaction between the power plant and the PCC unit, and the performance evaluation of decentralized control structures. A 613 MW three-pressure reheat NGCC with PCC using aqueous MEA was designed, including PCC process scale-up. Detailed dynamic process models of the power plant and the post-combustion unit were developed, and their validity was deemed sufficient for the purpose of application. Dynamic simulations of three gas turbine load-change ramp rates (2%/min, 5%/min and 10%/min) showed that the total stabilization times of the power plant's main process variables are shorter (10–30 min) than for the PCC unit (1–4 h). A dynamic interaction between the NGCC and the PCC unit is found in the steam extraction to feed the reboiler duty of the PCC unit. The transient performance of five decentralized PCC plant control structures under load change was analyzed. When controlling the CO2 capture rate, the power plant performs in a more efficient manner at steady-state part load; however, the PCC unit experiences longer stabilization times of the main process variables during load changes, compared with control structures without CO2 capture rate being controlled. Control of L/G ratio of the absorber columns leads to similar part load steady-state performance and significantly faster stabilization times of the power plant and PCC unit's main process variables. It is concluded that adding the PCC unit to the NGCC does not significantly affect the practical load-following capability of the integrated plant in a day-ahead power market, but selection of a suitable control structure is required for efficient operation of the process under steady-state and transient conditions.
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| 5. |
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| 6. |
- Normann, Fredrik, 1982, et al.
(författare)
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Partial Capture of Carbon Dioxide from Industrial Sources - A Discussion on Cost Optimization and the CO2 Capture Rate
- 2017
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 114, s. 113-121
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Konferensbidrag (refereegranskat)abstract
- This work discusses the cost optimal capture rate of absorption based carbon capture processes by a combination of process simulations and cost-estimation. The influence of the quality of the CO2 source (quantity, continuity and CO2 concentration) and the availability of low cost heat on the absolute and specific capture cost are highlighted. The results stress that partial capture of CO2 could lower the specific capture cost (€/ton CO2) and that the relation between capital expenditure and lowered energy demand should be reconsidered for cases with access to low-cost heat.
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| 7. |
- Òsk Gardarsdòttir, Stefanìa, 1987, et al.
(författare)
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Effects of CO2-absorption control strategies on the dynamic performance of a supercritical pulverized-coal-fired power plant
- 2017
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 56:15, s. 4415-4430
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Tidskriftsartikel (refereegranskat)abstract
- This work investigates the interactions that occur between a supercritical pulverized-coal-fired power plant and a downstream CO2-absorption process during load changes in the power plant, by linking the dynamic models of the two systems. The derived dynamic model for this integrated system is implemented in the dynamic modeling and simulation software Dymola. The operation of the integrated system is investigated in two modes of operation, considering various power plant loads and levels of steam availability for the CO2-absorption process. Several schemes for control of the CO2-absorption process, which have been suggested in the literature, are implemented for the integrated system and their effects on power plant operation are evaluated. Comparison of the simulation results obtained through varying the power plant load with and without CO2 absorption reveal that the CO2-absorption process has slower process dynamics than the power plant cycle, with the CO2 absorption stabilizing in more than 1 hour, while the power generation generally stabilizes in 6–9 minutes, in the power plant both with and without CO2 absorption. The control scheme used for the CO2-absorption process is important, as pairing of the control variables in relatively slow control loops increases the settling time of the power plant by up to 30 minutes with respect to power output. The results suggest that the investigated CO2-absorption process does not affect significantly the load-following capabilities of the power plant. Redirecting steam from the CO2-absorption process to the low-pressure turbine section in order to increase power generation (during a hypothetical peak-load demand) results in fluctuations of process variables in the power plant during the 2 hours of reduced steam availability to the CO2-absorption process. This is observed for both control schemes applied to the CO2-absorption process, and the power generation is not stabilized until the operation is restored to full load.
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| 8. |
- Skagestad, R., et al.
(författare)
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CO2stCap - Cutting Cost of CO2 Capture in Process Industry
- 2017
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 114, s. 6303-6315
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Konferensbidrag (refereegranskat)abstract
- This paper is a presentation of the CO2stCap project to be undertaken in the four year project period (2015 - 2019). The project focuses on partial CO2 capture in process industry and how this can be applied to reduce cost. By performing techno-economic analyses, the optimal capture rate, including optimal design, application and configuration for different industry sources can be obtained. Cost estimation methods are used as a basis to identify and verify potentials for cost reduction when applying different options for implementation of partial CO2 capture. CO2stCap. Industries studied in this project are pulp & paper, steel, cement and metallurgical production of silicon for solar cells.
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