Examensarbeten för kandidatexamen // Bachelor Theses

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Browsar Examensarbeten för kandidatexamen // Bachelor Theses efter Ämnesord "Chemical energy engineering"

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    Analys av designalternativ för snabbare dynamik i kolkraftverk med koldioxidavskiljning
    (2014) Elofsson, David; Höök, Mia; Johansson, Viktor; Mahmoud, Mohammed; Therning, Adam; Öberg, Simon; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and Environment
    Combustion of fossil fuels is today the dominating source of energy. During combustion, carbon dioxide is formed. The carbon dioxide accumulates in the atmosphere, which raises the global average temperature on earth through the so called greenhouse effect. The only way to reduce the emissions of carbon dioxide from combustion in a coal fired power plant is through carbon capture and storage (CCS). Post-combustion capture is a technology to separate carbon dioxide from the ue gas after the combustion for efficient transport and storage. The steady state operation of coal fired power plants with post combustion capture has already been thoroughly investigated on a pilot scale, however much work remains to investigate the plants dynamic operation. Due to the increasing amount of intermittent energy sources, such as wind and solar power, the energy system will require that the plants that run as base load today will be able to rapidly respond to changes in load. The present work investigates the operation of a coal fired power plant with post combustion capture during load changes. The response rate for different design options has been evaluated and discussed with respect to possible operating scenarios. The investigation does not include economic estimations, even though the importance of capture cost is discussed. According to the modelling it takes 90 to 105 seconds to reduce the electrical output from a power plant with CCS with one percentage point, depending on which load the change is made from. A coal fired power plant without the CCS technology is approximately eight times faster than a power plant with CCS. To increase the response rate of a post combustion system, a method for partial capture of the carbon dioxide was investigated. This method is referred to as CFCC (Constant Flue gas Carbon Capture). This option separates a constant amount of carbon dioxide regardless of the power plant load. In this case the system with CCS will change the load as fast as a power plant without CCS because the amount of ue gas and steam will be kept constant. This option is favorable when the power plant runs on low loads most of the time and increases the load to cover for the peaks in electricity demand. In this case the amount of carbon dioxide captured is less affected by the reduced capture capacity. Another option that was investigated was to temporarily stop the capture unit by reducing the steam extraction to the separation plant to improve the power plant response rate, a method referred to as EDCC (Emergency Dumping of Carbon Capture). In that case a lower degree of separation was accepted during the load changes, making it possible to follow the increased demand on electricity. With this method it is possible for a power plant with CCS to make a load change faster than a power plant without CCS. To stop the capture unit is the fastest way to make a load change of all investigated options. Reducing the steam drain to the separation plant for the short period of time required for the power plant to increase in load has only a slight effect on the overall capture rate.
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    Design av försöksanläggning för trycksatt rökgasrening vid oxy-fuelförbränning
    (2012) Borg, Anna; Djerv, Mattias; Fürst, Magnus; Nord, David; Olsson, Henrik; Rosander, Axel; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and Environment
    Reducing the CO2-pollution, resulting from the combustion of fossil coal for energy production, is important to affect environmental changes. One way to achieve a reduction is to use the oxy-fuel technology. The technology uses O2 and re-circulated flue gas during the combustion which results in a flue gas mainly consisting of CO2. The flue gas could then be compressed and stored without environmental effects. A problem that follows from the compression is the risk of acidification in sensitive parts of the process. Acidification can occur because of reactions following from the contact of condensed water and sulphur- and nitrogen-oxides which are also present in the flue gas. This report compiles and evaluates the basis of a scientific unit with the purpose of exploring the possibilities of extracting impurities of SOx and NOx from the flue gases. The dimensions of the unit are based on basic conditions, defined for an existing oxy-fuel process at Chalmers, and on the results of computer modelling. The computer models simulates chemical reactions in a gas phase reactor and in a two-phase reactor where the extraction of impurities is achieved by absorption. In addition to this, a research on possible, compatible measuring tools is done. To create the right conditions for extracting the impurites the flue gas has to be compressed to between 10 and 16 bars and cooled down to a temperature of 40◦C. These conditions are necessary for oxidizing NO to NO2 and other water-soluble nitrogen compounds, which reacts efficiently with water. The oxidation of NO to these nitrogen compounds occurs efficiently in a gas phase reactor of the size 10 liters and with residence time of 120 seconds. The final step is the extraction of the impurities where SOx and NOx are absorbed by water. The absorbtion occurs efficiently in a 10 liter twophase reactor at low temperatures and high pressures. To prevent acidification from occuring in sensitive parts of the process, it’s necessary to dry the flue gas before the compression, in order to minimize the condensate. A new system of measuring tools which are compatible with the type of measurements needed is required.
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    Produktion av metangas till Chalmers Eco-marathon
    (2013) Castillo, Gustav Ferrand-Drake del; Gustavsson, Andreas; Lindblom, Alexander; Stenberg, Viktor; Tegehall, Linda; Winberg, Kajsa; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and Environment
    Detta kandidatarbete behandlar tillverkning av tubreaktor och katalysator för att producera metan från syntesgas i laboratorieskala. Den tillverkade nickel-alumina katalysatorns prestanda utvärderades för att undersöka möjligheterna att producera metan i tillräcklig mängd för att driva ett fordon. Det finns en förhoppning att på Chalmers producera ett eget fordonsbränsle till studenternas bidrag till Shell Eco-marathon, en tävling för bränslesnåla fordon. Testerna av reaktorn används för att öka förståelsen för metaniseringsreaktionen samt att bidra till att förverkliga visionen med kommande kandidatarbeten. Projektet innefattade flera parallella delsteg. Reaktorframställning innefattade dimensionering, design och tillverkning av en reaktor. Framställning av katalysator innebar laborativt arbete för att ta fram katalysator med lämplig sammansättning och därefter belägga material som kunde placeras i reaktorn för att katalysera reaktionen. Framställningen av katalysatorn resulterade i en nickel-alumina katalysator bestående av 40 vikt-% nickel som med en specifik ytarea på cirka 150m2/g utgjorde beläggning på en monolit av keramiskt material som placerades i reaktorn. Tillverkad reaktor bestod av två rostfria stålrör som satts ihop genom svetsning och var gängade med gastäta kopplingar. Upprepade tester genomfördes enligt framtagen försöksmatris där temperatur, volymsflöde och utspädning varierades vilket resulterade i ett maximalt utbyte av 80.2% metan. Detta är jämförbart med det resultat som ett forskarlag i Sydkorea uppnått med liknande katalysator. I nuvarande skala med 0.16 g nickel skulle det ta lite mer än tre dagar att producera energiinnehållet motsvarande en liter bensin. Vid tester observerades nedsättning av katalysatorns funktion på grund av bildade kolavlagringar. En viss del av kolavlagringarna kunde tas bort genom oxidering vid hög temperatur. Det förekom inga större skillnader mellan de katalysatorprov som användes vilket tyder på tillförlitlig produktion för denna typ av katalysator. Arbetet har redovisats på två planscher som ställts ut vid Chalmers Energikonferens och tävlingen Shell Eco-marathon i Rotterdam i maj 2013