| 1. |
- Aslanzadeh, Solmaz, et al.
(författare)
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An Overview of Existing Individual Unit Operations
- 2014
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Ingår i: Biorefineries. - : Elsevier Inc.. - 9780444594983
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Bokkapitel (refereegranskat)abstract
- BACKGROUND: Because of its extreme toxicity for microorganisms, the limonene content of citrus wastes (CWs) has been a major obstacle to the conversion of CWs to biofuels. The main objective of this study was to develop a new process for the utilization of CWs that can be economically feasible when the supply of CW is low.RESULTS: Steam explosion pre-treatment was applied to improve the anaerobic digestibility of CWs, resulting in a decrease of initial limonene concentration by 94.3%. A methane potential of 0.537 ± 0.001 m 3 kg -1 VS (volatile solids) was obtained during the following batch digestion of treated CWs, corresponding to an increase of 426% compared with that of the untreated samples. Long-term effects of the treatment were further investigated by a semi-continuous co-digestion process. A methane production of 0.555 ± 0.0159 m 3 CH 4 kg -1 VS day -1 was achieved when treated CWs (corresponding to 30% of the VS load) were co-digested with municipal solid waste.CONCLUSION: The process developed can easily be applied to an existing biogas plant. The equipment cost for this process is estimated to be one million USD when utilizing 10 000 tons CWs year -1. 8.4 L limonene and 107.4 m 3 methane can be produced per ton of fresh citrus wastes in this manner.
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| 2. |
- Berntsson, Thore, 1947, et al.
(författare)
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Towards Sustainabel Oil Refinery - Pre-study for larger co-operation project
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this report, the Chalmers EnergiCentrum (CEC) presents the results of a pre-study commissioned by Preem relating to the effective production of future vehicle fuels.This pre-study was made up of three studies focusing on energy streamlining, the utilisation of waste heat and carbon-dioxide separation and biorefinement relating to the gasification and hydration of vegetable oils. One of the common starting points for these studies was the current situation at the Preem refineries in Göteborg and Lysekil from where the measurement data were obtained and analysed. The report summarises the knowledge situation based on current research in the individual technical fields. The results present some interesting future opportunities for developing the sustainable production of future vehicle fuels. The sections vary, as the areas that have been examined differ and the sections have been written by different people. The reports ends with some joint conclusions and a number of questions which could be included and answered in a more extensive future main study, as part of a developed research partnership between Preem and the Chalmers University of Technology. The preliminary results of this work were analysed with the client at workshops on 1 October and 29 November 2007. The report is written in English combined with an extensive summary in Swedish including a proposal on a future main study. The study was conducted by the Chalmers EnergiCentrum (CEC), in collaboration with a number of researchers in the CEC’s network. They included Thore Berntsson, Jessica Algehed, Erik Hektor and Lennart Persson Elmeroth, all from Heat and Power Technology, Börje Gevert, Chemical and Biological Engineering, Tobias Richards, Forest Products and Chemical Engineering, Filip Johnsson and Anders Lyngfelt, Energy Technology, and Per-Åke Franck and Anders Åsblad, CIT Industriell Energianalys AB. The client, Preem, was represented by Bengt Ahlén, Sören Eriksson, Johan Jervehed, Bertil Karlsson, Gunnar Olsson, Ulf Kuylenstierna, Stefan Nyström, Martin Sjöberg and Thomas Ögren. Tobias Richards was responsible for compiling the report and Bertil Pettersson was the project manager.
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| 3. |
- Chandolias, Konstantinos, 1985-, et al.
(författare)
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Combined gasification-fermentation process in waste biorefinery
- 2018
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Ingår i: Waste Biorefinery. - : Elsevier. - 9780444639929
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Bokkapitel (refereegranskat)abstract
- Thermal processes of wastes lead to production of energy in form of electricity and/or heat. However, if the goal is to produce materials, thermochemical processes can be applied. These processes via e.g. gasification produce raw syngas that is a mixture of principally H2, CO and CO2, with some impurities. This raw syngas is traditionally cleaned and catalytically treated via chemical processes such as Fischer-Tropsch. However, as there is a variety of microorganisms that can assimilate syngas, this gas can be used as a substrate to produce different chemicals via biochemical routes. This chapter is dedicated to describe an efficient thermochemical-biochemical route of waste treatment. The gasification process, the design and the factors that affect the syngas composition are firstly described. Thereafter, the microbiology, biochemical reactions, metabolic pathways and process conditions toward production of several metabolic products from syngas such as carboxylic acids, ethanol, butanol, 2,3-butanediol, methane and biopolymers are presented.
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| 4. |
- Eboh, Francis Chinweuba, et al.
(författare)
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Economic evaluation of improvements in a waste-to-energy combined heat and power plant
- 2019
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Ingår i: Waste Management. - : Elsevier. - 0956-053X .- 1879-2456.
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Tidskriftsartikel (refereegranskat)abstract
- Improving the efficiency of waste-to-energy combined heat and power plants increases their production of both electricity and heat. Economic evaluation of such improvements enables adequate decisions to be made between the various alternatives with respect to economic viability of the plant. In this study, the cost and profitability of different modifications to improve efficiency in a waste-to-energy plant are considered: these include the re-arrangement of air heaters, the introduction of a reheater, flue gas condensation (FGC) and an integrated gasification-combustion process. The base case and the modifications are evaluated and compared when operating either as a combined heat and power plant or as a power plant. Modelling, simulation and cost estimations were performed with the Aspen Plus software. Although the integrated gasification-combustion technology with FGC has the highest exergy efficiency, its higher capital cost is greater than all of the other alternatives. Modification 6, which involves both re-arrangement and changing the air heating medium has the lowest capital cost with respect to enhancing exergy efficiency. Modifications 1 and 7, involving FGC, are the best alternatives for the capital cost per total unit of revenue generated. These modifications not only provides the highest heat production but also the highest net present value (NPV). The base case and the modifications investigated all have positive NPV, indicating that a waste-to-energy combined heat and power plant is an attractive investment. However, an increase of about 122% in the gate fees would be required for a system with only electricity production to be profitable.
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| 5. |
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| 6. |
- Eboh, Francis Chinweuba, et al.
(författare)
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Evaluating improvements in a waste-to-energy combined heat and power plant
- 2019
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Ingår i: Case Studies in Thermal Engineering. - : Elsevier. - 2214-157X.
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Tidskriftsartikel (refereegranskat)abstract
- Evaluation of different alternatives for enhancement in a waste combustion process enables adequate decisions to be made for improving its efficiency. Exergy analysis has been shown be an effective tool in assessing the overall efficiency of a system. However, the conventional exergy method does not provide information of the improvements possible in a real process. The purpose of this paper is to evaluate state-of-the art techniques applied in a municipal solid-waste fired heat and power plant. The base case plant is evaluated first; the results are then used to decide upon which technical modifications should be introduced and they are thereafter evaluated. A modified exergy-based method is used to discover the improvement potential of both the individual components and the overall base case plant. The results indicate that 64% of exergy destruction in the overall process can theoretically be improved. The various modifications selected involve changing the bed material, using a gasifier followed by a gas boiler and incorporating a more durable material into the boiler walls. In addition, changing the heating medium of the incoming air (from steam to flue gas) along with a reduction in the stack temperature and the integration of flue gas condensation were considered for utilizing the exergy in the flue gases. The modification involving gasifier, gas boiler and flue gas condensation proved to be the best option, with the highest exergy efficiency increment of 21%.
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| 7. |
- Eboh, Francis Chinweuba, et al.
(författare)
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Method of Estimating Absolute Entropy of Municipal Solid Waste
- 2016
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Ingår i: World Academy of Science, Engineering and Technology, International Journal of Environmental, Chemical, Ecological, Geological and Geophysical Engineering. - 2010-3778. ; 10:7, s. 689-694
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Tidskriftsartikel (refereegranskat)abstract
- Entropy, as an outcome of the second law of thermodynamics, measures the level of irreversibility associated with any process. The identification and reduction of irreversibility in the energy conversion process helps to improve the efficiency of the system. The entropy of pure substances known as absolute entropy is determined at an absolute reference point and is useful in the thermodynamic analysis of chemical reactions; however, municipal solid waste (MSW) is a structurally complicated material with unknown absolute entropy. In this work, an empirical model to calculate the absolute entropy of MSW based on the content of carbon, hydrogen, oxygen, nitrogen, sulphur, and chlorine on a dry ash free basis (daf) is presented. The proposed model was derived from 117 relevant organic substances which represent the main constituents in MSW with known standard entropies using statistical analysis. The substances were divided into different waste fractions; namely, food, wood/paper, textiles/rubber and plastics waste and the standard entropies of each waste fraction and for the complete mixture were calculated. The correlation of the standard entropy of the complete waste mixture derived was found to be somsw= 0.0101C + 0.0630H + 0.0106O + 0.0108N + 0.0155S + 0.0084Cl (kJ.K-1.kg) and the present correlation can be used for estimating the absolute entropy of MSW by using the elemental compositions of the fuel within the range of 10.3% ≤ C ≤ 95.1%, 0.0% ≤ H ≤ 14.3%, 0.0% ≤ O ≤ 71.1%, 0.0 ≤ N ≤ 66.7%, 0.0% ≤ S ≤ 42.1%, 0.0% ≤ Cl ≤ 89.7%. The model is also applicable for the efficient modelling of a combustion system in a waste-to-energy plant.
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| 8. |
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| 9. |
- Gustafsson, Christina M, 1970, et al.
(författare)
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Pyrolysis kineticts of washed precipitated lignin
- 2009
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Ingår i: BioResources. - 1930-2126 .- 1930-2126. ; 4:1, s. 26-37
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Tidskriftsartikel (refereegranskat)abstract
- This article describes the pyrolysis behavior of precipitated washed lignin in a Laminar Entrained Flow Reactor between 700 and 1000°C and at different residence times. Lignin was precipitated by acidification of softwood black liquor using CO2. After acid washing, the solid material was dried and sieved (80-100 μm). This material was then fed into the reactor at a rate of about 0.1 g/min. The formed gases were analyzed with respect to CO, CO2, and CH4, and char was collected and weighed. A traditional first order Arrhenius kinetic expression, based on the temperature of the particles with respect to residence time, was adapted to the experimental results. The activation energy was found to be 32.1 kJ/mol. The low ash content in the washed lignin gave a very low solid material residue after the reactor.
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| 10. |
- Harvey, Simon, 1965, et al.
(författare)
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Sustainable Process Solutions in Göteborg, Sweden - an Overview of Experience and Challenges from a Chemical Engineering Education Case Study Course at Chalmers
- 2006
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Ingår i: Engineering Education in Sustainable Development international conference, Lyon, France, October 4-6, 2006.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Environmentally Sustainable Process Technology international masters program at Chalmers University of Technology in Göteborg, Sweden, aims to provide students with the skills necessary to develop sustainable process solutions. The program includes courses in core chemical engineering as well as applied environmental engineering areas. A key feature of the program is the Case Study project course, in which the knowledge acquired in the program’s core courses is used to solve an industrially relevant process engineering problem using systems engineering methodology. The problem analysis and assessment of the proposed solution focus on various aspects of sustainability, including technical feasibility, economic viability and environmental performance. The course includes a field trip to the Industrial Symbiosis project in Kalundborg, Denmark. The Case Study course has been ongoing for nine years. Initial problems and development efforts are described in the paper. Focusing all projects within the Göteborg area has proven to be a major improvement to the project in that it has encouraged systemic thinking by providing a context for the students to relate to, thus enabling them to adopt the holistic attitude necessary for sustainable development. Examples of case study projects from previous years are presented to illustrate how chemical engineering education can introduce students to using process engineering methods and tools to identify sustainable process solutions, accounting for limitations in the surrounding system.
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