| 1. |
- Ali, Hassan, et al.
(författare)
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Cost estimation of heat recovery networks for utilization of industrial excess heat for carbon dioxide absorption
- 2018
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 74, s. 219-228
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Tidskriftsartikel (refereegranskat)abstract
- The absorption of CO 2 using solvents (e.g., amines) is considered a state-of-the-art, albeit energy-intensive process for CO 2 capture. While it is generally recognized that the utilization of waste heat has potential to reduce the energy-associated costs for CO 2 capture, the cost of waste heat recovery is seldom quantified. In this work, the cost of heat-collecting steam networks for waste heat recovery for solvent regeneration is estimated. Two types of networks are applied to waste heat recovery from the flue gases of four process industries (cement, silicon, iron & steel, and pulp & paper) via a heat recovery steam generator (HRSG). A novel approach is presented that estimates the capital and operational expenditures for waste heat recovery from process industries. The results show that the overall cost (CAPEX + OPEX) of steam generated from one hot flue gas source is in the range of 1.1–4.1 €/t steam. The cost is sensitive to economic parameters, installation factors, the overall heat transfer coefficient, steam pressure, and to the complexity of the steam network. The cost of steam from an existing natural gas boiler is roughly 5–20-times higher than that of steam generated from recovered waste heat. The CAPEX required to collect the heat is the predominant factor in the cost of steam generation from waste heat. The major contributor to the CAPEX is the heat recovery steam generator, although the length of the steam pipeline (when heat is collected from two sources or over long distances) is also important for the CAPEX.
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| 2. |
- Andersson, Viktor, 1983
(författare)
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Excess heat utilisation in oil refineries - CCS and algae-based biofuels
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of this thesis is to investigate two different concepts for CO2 mitigation, from a system perspective, in relation to the oil refining industry: CO2 capture and storage; and algae-based biofuels. For all these processes, process integration with an oil refinery is assumed. The oil refinery sector is a major emitter of CO2 and is responsible for 9% of the industrial emissions of CO2 worldwide. Oil refineries have large amounts of unused excess heat, which can be used to satisfy the heat demands of a CO2 capture plant, a land-based algal cultivation facility, or an algae-based biofuel process. The use of this excess heat significantly reduces the cost for CO2 capture, while an economic evaluation for algae-based biofuels has not been made.Since the amount of heat available from the oil refinery´s processes increase with decreasing temperature in the stripper reboiler, it was investigated how much heat was available at different temperatures. It was also investigated how the decreased temperature would affect the heat demand of CO2 capture processes that use MEA or ammonia as the absorbent. The findings show that it is possible to capture more CO2 using excess heat when the temperature in the stripper reboiler is decreased. For the MEA process, the lower limit of the temperature interval investigated showed the maximum CO2 capture rate, while the ammonia process benefitted from a lower temperature than the standard temperature but showed maximal CO2 capture rate above the lower limit. These results are valid only when using excess heat to satisfy the entire heat demand. At the case study refinery, the available excess heat could satisfy between 28% and 50% of the heat demand of the MEA process when treating the flue gases from all chimneys, depending on the temperature in the stripper reboiler. This utilisation of excess heat represents a way to reduce significantly the costs for CCS in an oil refinery. Land-based cultivation of algae proved to be unsuitable for the utilisation of excess heat. Since the cultivation pond is exposed to wind, rain, and cold, the heat demand fluctuates strongly over the year, making the pond an unstable recipient of the excess heat.Three types of biofuel processes based on microalgae and macroalgae were investigated with respect to integration with the oil refinery. For the algae-based biofuel processes, heat integration and material integration combined to increase the efficiency of the system. When two different build margin technologies (with different CO2 emission factors) are employed for electricity production, macroalgae-based biofuel production appears to be the more robust process from the perspective of CO2 due to the lower electricity demands of the algal cultivation and harvesting phases.
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| 3. |
- Andersson, Viktor, 1983, et al.
(författare)
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Techno-economic analysis of excess heat driven post-combustion CCS at an oil refinery
- 2016
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 45, s. 130-138
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Tidskriftsartikel (refereegranskat)abstract
- Carbon capture and storage may, as a bridging technology, rapidly decrease CO2 emissions in the industrial sector. In this paper, a techno-economic study of a future MEA carbon capture plant implemented at a case study oil refinery is presented. Costs are calculated for six setups of carbon capture at the refinery. Excess heat from the refinery processes is used in the capture plant for regeneration of the absorption fluid, and the stripper reboiler temperature is varied to increase the extractable of excess heat. Supplementary heating is carried out with a heat pump. The number of chimneys to be included in the capture process is also varied, resulting in different CO2 concentrations and amounts of CO2 at the inlet of the capture plant. Results show that the specific cost for carbon capture increases as the amount of captured carbon increases due to the need for heat pumps. The costs are in the range of 41-57(sic)/t for the low-temperature cases (T-Reb =90 degrees C) and 39-44(sic)/t for the high-temperature cases (T-Reb = 120 degrees C).
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| 4. |
- Beukes, Eldré W., et al.
(författare)
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Development and technical functionality of an Internet-based intervention for tinnitus in the UK
- 2016
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Ingår i: Internet Interventions. - : Elsevier. - 2214-7829. ; 6, s. 6-15
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Tidskriftsartikel (refereegranskat)abstract
- PurposeCreative approaches to improve access to evidence-based tinnitus treatments are required. The purpose of this study was to develop an Internet-based cognitive behavioural therapy (iCBT) intervention, for those experiencing tinnitus in the United Kingdom (UK). Furthermore, it aimed, through technical functionality testing, to identify specific aspects of the iCBT that require improving.MethodAn innovative iCBT intervention for treating tinnitus in the UK has been developed using a cognitive-behavioural theoretical framework. This iCBT was evaluated by two user groups during this developmental phase. Initially, five expert reviews evaluated the intervention, prior to evaluation by a group of 29 adults experiencing significant levels of tinnitus distress. Both groups evaluated iCBT in an independent measures design, using a specifically designed satisfaction outcome measure.ResultsOverall, similar ratings were given by the expert reviewers and adults with tinnitus, showing a high level of satisfaction regarding the content, suitability, presentation, usability and exercises provided in the intervention. The iCBT intervention has been refined following technical functionality testing.ConclusionsRigorous testing of the developed iCBT intervention has been undertaken. These evaluations provide confidence that further clinical trials can commence in the UK, to assess the feasibility and effectiveness of this iCBT intervention for tinnitus.
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