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POWER PRODUCTION FROM RENEWABLE ENERGY AY 2015-16 8th July 2016 Prof. Silva and Manzolini Time: 1,5 hours Instructions for the examination: 1) Clearly indicate your name on all the sheets you will deliver. 2) The score refers to exercises done in a comprehensive manner with exact numerical results. Numerical results correct but not accompa- nied by explanations will not be taken into account. The final score will be normalized according to the average results. 3) Answer briefly and clearly only to the asked questions. Calculations and explanations which do not respond to the questions will not be considered for evaluation even if correct. 4) Talking with colleagues and / or cheating will cause the cancellation of the exam. 5) All the needed data for the resolution of exercises lies on this paper. It is NOT ALLOWED to use material other than this (e.g. books, clipboard etc.). Exercise 1 (17 points) A biomass plant adopts wood pellets as fuel with the following characteristics : wood pellets %, weight dry basis C 47.10 H 6.73 O 45.81 N 0.15 S 0.01 Cl 0.00 ash 0.20 LHV, kJ/kg, dry basis 18607 HHV, kJ/kg, dry basis 20086 Moisture content, % 8.50 Density (as received), kg/m3 700.00 Calculate the LHV and the HHV of the as received feedstock (3 points). The biomass is gasified as received using sub-stoichiometric air with an air-to-fuel ratio equal to 2. Assuming a cold gas efficiency of 70% (LHV syngas/LHVfuel) and a LHV power output of the syngas equal to 25 MW, ca l- culate the air and the biomass flow rates (3 points). The syngas is compressed by means of an electrical -driven compressor (starting from ambient conditions) and then used in a gas turbine cycle with the following characteristics: Ambient temperature [°C] 15 Compression ratio 12 Ambient pressure [bar] 1.013…