| 1. |
- Andersson, Jim, et al.
(författare)
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System studies on biofuel production via integrated biomass gasification
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A large number of national and international techno-economic studies on industrially integrated gasifiers for production of biofuels have been published during the recent years. These studies comprise different types of gasifiers (fluidized bed, indirect and entrained flow) integrated in different industries for the production of various types of chemicals and transportation fuels (SNG, FT-products, methanol, DME etc.) The results are often used for techno-economic comparisons between different biorefinery concepts. One relatively common observation is that even if the applied technology and the produced biofuel are the same, the results of the techno-economic studies may differ significantly.The main objective of this project has been to perform a comprehensive review of publications regarding industrially integrated biomass gasifiers for motor fuel production. The purposes have been to identify and highlight the main reasons why similar studies differ considerably and to prepare a basis for “fair” techno-economic comparisons. Another objective has been to identify possible lack of industrial integration studies that may be of interest to carry out in a second phase of the project.Around 40 national and international reports and articles have been analysed and reviewed. The majority of the studies concern gasifiers installed in chemical pulp and paper mills where black liquor gasification is the dominating technology. District heating systems are also well represented. Only a few studies have been found with mechanical pulp and paper mills, steel industries and the oil refineries as case basis. Other industries have rarely, or not at all, been considered for industrial integration studies. Surprisingly, no studies regarding integration of biomass gasification neither in saw mills nor in wood pellet production industry have been found.There are several reasons why the results of the reviewed techno-economic studies vary. Some examples are that different system boundaries have been set and that different technical and economic assumptions have been made, product yields and energy efficiencies may be calculated using different methods etc. For obvious reasons, the studies are not made in the same year, which means that different monetary exchange rates and indices have been applied. It is therefore very difficult, and sometimes even impossible, to compare the technical as well as the economic results from the different studies. When technical evaluations are to be carried out, there is no general method for how to set the system boundaries and no right or wrong way to calculate the system efficiencies as long as the boundaries and methods are transparent and clearly described. This also means that it becomes fruitless to compare efficiencies between different concepts unless the comparison is done on an exactly equal basis.However, even on an equal basis, a comparison is not a straight forward process. For example, calculated efficiencies may be based on the marginal supply, which then become very dependent on how the industries exploit their resources before the integration. The resulting efficiencies are therefore very site-dependent. Increasing the system boundaries to include all in- and outgoing energy carriers from the main industry, as well as the integrated gasification plant (i.e. total plant mass and energy balance), would inflict the same site-dependency problem. The resulting system efficiency is therefore a measure of the potential improvement that a specific industry could achieve by integrating a biomass gasification concept.When estimating the overall system efficiency of industrial biorefinery concepts that include multiple types of product flows and energy sources, the authors of this report encourage the use of electrical equivalents as a measure of the overall system efficiency. This should be done in order to take the energy quality of different energy carriers into concern.In the published economic evaluations, it has been found that there is a large number of studies containing both integration and production cost estimates. However, the number of references for the cost data is rather limited. The majority of these have also been published by the same group of people and use the same or similar background information. The information in these references is based on quotes and estimates, which is good, however none of these are publically available and therefore difficult to value with respect to content and accuracy.It has further been found that the variance in the operational costs is quite significant. Something that is particularly true for biomass costs, which have a high variance. This may be explained by natural variations in the quality of biomass used, but also to the different markets studied and the dates when the studies were performed. It may be seen from the specific investment costs that there is a significant spread in the data. It may also be seen that the differences in capital employed and process yields will result in quite large variations in the production cost of the synthetic fuels. On a general note, the studies performed are considering future plants and in some cases assumes technology development. It is therefore relevant to question the use of today’s prices of utilities and feedstock’s. It is believed that it would be more representative to perform some kind of scenario analysis using different parameters resulting in different cost assumptions to better exemplify possible futures.Due to the surprising lack of reports and articles regarding integration of biomass gasifiers in sawmills, it would be of great interest to carry out such a study. Also larger scale wood pellet production plants could be of interest as a potential gasification based biorefinery.
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| 2. |
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| 3. |
- Malek, Laura, et al.
(författare)
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Catalytic Abatement of NH3 Using NOx in Reducing Environment
- 2015
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Ingår i: Topics in Catalysis. - : Springer Science and Business Media LLC. - 1572-9028 .- 1022-5528. ; 58:14-17, s. 993-1001
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Tidskriftsartikel (refereegranskat)abstract
- Removal of ammonia from synthesis gas is an important step in gas purification to prevent poisoning of downstream catalyst or formation of nitrogen oxides on combustion. This publication proposes that ammonia can be removed by using selective catalytic abatement with NOx, not unlike the selective catalytic reduction of NOx but under reducing environment. Two different catalysts have been used for the experiments; V2O5/WO3/TiO2 and H-mordenite. The conducted experiments were performed on a model synthesis gas and served to investigate the selectivity and to some extent the longevity of these catalysts under reducing atmosphere, and also the effect of water on the catalyst performance. A number of catalyst characterisation methods have been used to obtain a better understanding of the catalyst morphology and surface. The methods that have been used are Raman spectroscopy, Brunauer–Emmett–Teller nitrogen adsorption, X-ray diffraction and temperature programmed desorption using ammonia. The initial performance with respect to conversion and selectivity is good for the vanadia-based catalyst, but it is not chemically stable. This is manifested by a change in the catalyst crystal structure suggesting an oxygen depletion of the titania support and decreased activity with time-on-stream. The mordenite catalyst is stable but the activity and selectivity, especially to avoid the formation of N2O, needs to be improved before implementation. Based on the experimental work performed, none of the catalysts in their present state are suitable for the proposed operating conditions.
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| 4. |
- Malek, Laura, et al.
(författare)
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Measuring and ensuring the gas quality of the Swedish gas grid
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- When there is more renewable gas being produced, and exported to the natural gas grid, there is a new situation for the grid operators which, in extension, creates new circumstances with respect to measuring and ensuring the gas quality on the grid. The renewable gas is today mainly produced by anaerobic digestion, but near-term future sources may be methane from thermochemical conversion of lignocellulose and hydrogen produced from intermittent electricity stemming from wind and solar resources; indeed, the first type of gas is currently demonstrated in the Swedish context in Gothenburg and the second type in Germany.
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| 5. |
- Malek, Laura
(författare)
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Renewable gas in a Swedish context
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In order to increase the use of sustainable energy in Sweden, it is necessary to substitute fossil energy carriers with renewable counterparts. Synthetic natural gas (SNG) produced from renewable resources via biomass gasification and methanation could replace a proportion of the natural gas used in Sweden. In order to facilitate the implementation and expansion of SNG production and use in Sweden, development is necessary at multiple levels. In this thesis I have dentified and investigated possible improvements for three different levels: national distribution, industrial production and specific plant improvements. There is a clear advantage in using the existing Swedish gas grid for the transportation and distribution of renewable gas. However, in order to inject renewable gas into the gas grid, strategies are required for handling gases of mixed qualities. An industry-wide task group was formed to develop guidelines for mixed quality gas for the Swedish gas grid, and Lund University and E.ON were assigned the task of drawing upon experience from other European countries to identify suitable strategies. Two strategies were identified: the flow-weighted heating value method and the state reconstruction tool. As a result of the work performed by the task group, the Swedish gas industry standard has been updated to include these two methods. By integrating biomass gasification and the SNG production process with an existing host plant, it is possible to reduce the investment and operating costs, compared to stand-alone production, while simultaneously exploiting synergistic effects by exchanging material and energy streams with the host plant. The majority of the integrated systems studied showed a system efficiency equal to those of stand alone plants. The estimated SNG production cost for integrated cases is sufficiently low to compete with the cost of natural gas to household consumers, but not with the cost to commercial customers. It is imperative that SNG can be produced free from impurities in order to be approved for injection into the grid. Different aspects of gas cleaning technologies for tar and ammonia removal were studied. First, a proof-of-concept regenerative reverse flow reactor was constructed for thermal cracking of tars. This method showed the ability to crack tar compounds and has the potential to be a highly efficient process step in a biomass gasification gas-cleaning train. Secondly, the possibility of regenerating the spent scrubber liquid used for tar removal in gasification pants, via centrifugation, was studied in order to improve the process economy. The results showed that centrifugation is a suitable method for removing heavy insoluble tars from the scrubber liquid, thus extending its lifetime considerably. Lastly, the possibility of removing ammonia by reaction with nitrous oxides over a vanadium-based or zeolite catalyst was investigated. Neither of these catalysts was deemed suitable due to either poor conversion or deactivation of the catalyst over time. From the results of these studies, it was concluded that the current outlook for Swedish SNG production by biomass gasification is not very promising. As natural gas in Sweden is used mainly as a fuel for industrial heat and power production, producing renewable SNG from biomass would appear to be a wasteful detour compared to the direct combustion of the biomass. This is especially true as the production of SNG is currently not sufficiently efficient for SNG to be produced at a cost that is competitive with that of natural gas. Transforming biomass into a useful vehicle fuel would be a far better use of renewable resources. However, clear regulations regarding the end use of renewable SNG would then have to be developed.
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| 6. |
- Malek, Laura, et al.
(författare)
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Scrubber liquid recovery in biomass gasification plants: centrifugation as a method for tar separation
- 2016
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Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media LLC. - 2190-6815 .- 2190-6823. ; 6:3, s. 261-269
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Tidskriftsartikel (refereegranskat)abstract
- Many gasification plants use scrubber systems for the removal of tars from producer gas. The cost of the scrubber liquid represents a considerable part of the operating cost, which could be decreased by regenerating the spent scrubber liquid by separating it from ash residues and heavy tars. In this study, different types of spent scrubber liquids were regenerated using a centrifuge. The effect of centrifugation time (1.5–10 min) and sample temperature (50–90 °C) on the separation efficiency was studied. Based on the results, the separation of tars from the scrubber liquids can be ranked as follows: diesel > RME > linoleic acid > linseed oil > rapeseed oil > motor oil. This ranking correlates to the viscosity of the different scrubber liquids, with the separation efficiency increasing with decreasing scrubber liquid viscosity. The best separation efficiency was achieved for scrubber liquids with low viscosity at 90 °C and 10 min of centrifugation time. The results obtained indicate that centrifugation can be used for the regeneration of spent scrubber liquid.
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| 7. |
- Ramani-Chander, Anusha, et al.
(författare)
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Applying systems thinking to identify enablers and challenges to scale-up interventions for hypertension and diabetes in low-income and middle-income countries : protocol for a longitudinal mixed-methods study
- 2022
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Ingår i: BMJ Open. - : BMJ Publishing Group Ltd. - 2044-6055. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: There is an urgent need to reduce the burden of non-communicable diseases (NCDs), particularly in low-and middle-income countries, where the greatest burden lies. Yet, there is little research concerning the specific issues involved in scaling up NCD interventions targeting low-resource settings. We propose to examine this gap in up to 27 collaborative projects, which were funded by the Global Alliance for Chronic Diseases (GACD) 2019 Scale Up Call, reflecting a total funding investment of approximately US$50 million. These projects represent diverse countries, contexts and adopt varied approaches and study designs to scale-up complex, evidence-based interventions to improve hypertension and diabetes outcomes. A systematic inquiry of these projects will provide necessary scientific insights into the enablers and challenges in the scale up of complex NCD interventions.Methods and analysis: We will apply systems thinking (a holistic approach to analyse the inter-relationship between constituent parts of scaleup interventions and the context in which the interventions are implemented) and adopt a longitudinal mixed-methods study design to explore the planning and early implementation phases of scale up projects. Data will be gathered at three time periods, namely, at planning (T-P), initiation of implementation (T-0) and 1-year postinitiation (T-1). We will extract project-related data from secondary documents at T-P and conduct multistakeholder qualitative interviews to gather data at T-0 and T-1. We will undertake descriptive statistical analysis of T-P data and analyse T-0 and T-1 data using inductive thematic coding. The data extraction tool and interview guides were developed based on a literature review of scale-up frameworks.Ethics and dissemination: The current protocol was approved by the Monash University Human Research Ethics Committee (HREC number 23482). Informed consent will be obtained from all participants. The study findings will be disseminated through peer-reviewed publications and more broadly through the GACD network.
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| 8. |
- Tunå, Per, et al.
(författare)
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Regenerative reverse-flow reactor system for cracking of producer gas tars
- 2014
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Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media LLC. - 2190-6815 .- 2190-6823. ; 4:1, s. 43-51
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Tidskriftsartikel (refereegranskat)abstract
- The gas produced in a biomass gasifier contains high amounts of tars which have to be removed prior to downstream utilization. Calcined dolomite is catalytically active for tar cracking reactions and resistant to sulfur poisoning. In this study, calcined dolomite was used as bed material in a reverse-flow reactor for cracking of tars in a model synthesis gas. 1-methylnaphthalene was used as model tar compound at a concentration of 15,000 mg/Nm3. The reactor system was operated at temperatures between 700 and 850 °C in the active zone. Total tar conversion was over 95 % for the system under reverse-flow conditions at the highest temperature. Already at the lowest temperature, up to 78 % of the 1-methylnaphthlene was converted, but mainly to other more stable tar compounds such as naphthalene and benzene, reaching a total tar conversion of only 23 %. To produce tar-free gas, higher temperatures are thus needed. The use of very high temperatures does, however, lead to a significant decrease in the specific area of the dolomite, as shown by BET surface measurements. The dolomite was further characterized with x-ray diffraction and energy dispersive spectroscopy.
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