EML4450L25

EML4450L25 - S ustainable E nergy S cience and E ngineering...

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Unformatted text preview: S ustainable E nergy S cience and E ngineering C enter Bio Fuel Production Reference: Donald L. Klass, Biomass for Renewable Energy, Fuels and Chemicals, Academic Press, 1998. http://www.energy.kth.se/compedu/webcompedu/media/Lecture_note s/S1B11C2.pdf http://www.energy.kth.se/compedu/webcompedu/media/Lecture_note s/BiomassCombustionStudyPack.pdf Source: Miroslav Petrov @ KTH S ustainable E nergy S cience and E ngineering C enter Conversion Methods S ustainable E nergy S cience and E ngineering C enter Fuel from the Forest? S ustainable E nergy S cience and E ngineering C enter Gasifiers Types Source: Ohlstrm M. et al. New concepts for biofuels in transportation, VTT research notes 2074, Technical Research Center of Finland, Espoo 2001. S ustainable E nergy S cience and E ngineering C enter NG-based or Wood-based Methanol Synthetic methanol from natural gas or biomass: Source: Ohlstrm M. et al. New concepts for biofuels in transportation, VTT research notes 2074, Technical Research Center of Finland, Espoo 2001. S ustainable E nergy S cience and E ngineering C enter Steam Reforming and Water-Gas-Shift Gas mixture for fuel synthesis (syngas) can be produced from hydrocarbon reforming with steam, or from biomass gasification (preferably oxygen- blown gasification to avoid the presence of inert nitrogen). steam-methane reforming: CH 4 + H 2 O CO + 3H 2 (very endothermic) The product gas is in reality a mixture of CO, CO 2 , H 2 , water vapours, and traces of reactants. It has a high energy value. Product gas from biomass gasification needs to be enriched with hydrogen to the required molar ratio CO/H 2 for the methanation reaction to proceed. This is done by the water-gas-shift reaction, where a certain part of the CO in the product gas is sacrificed to produce H 2 . water-gas-shift reaction: CO + H 2 O CO 2 + H 2 (slightly exothermic) S ustainable E nergy S cience and E ngineering C enter Methanol Synthesis The syngas after the water-gas-shift reaction is fed to the methanol reactor vessel, where on the surface of catalysts the CO and CO 2 react with H 2 to form CH 3 OH mixed with water, also denoted as MeOH. The methanol is then distilled out, which is an energy demanding process. methanol synthesis: CO + 2H 2 CH 3 OH (exothermic) CO 2 + 3H 2 CH 3 OH + H 2 O (slightly exothermic) If hydrogen from additional source is added to the process, so that carbon is not sacrificed to produce hydrogen, the methanol yield can be doubled. S ustainable E nergy S cience and E ngineering C enter Problems with Methanol Fuel Methanol is a perfect fuel for gasoline (Otto) engines or gas turbines. However, there are several major disadvantages with it: Very toxic Good solvent dilutes old deposits in the fuel system and washes them to the engine, destroys rubber hoses/gaskets/seals Corrosive to certain steels Lower energy per mass/volume ratio compared to gasoline ( ~ two times lower energy value) Difficult cold start of the engine due to low vapour pressure S...
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EML4450L25 - S ustainable E nergy S cience and E ngineering...

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