A butyl rubber bag of total volume 3.0 m3 is used as a biogas digester. Each day it is fed an input of 0.20 m3 of slurry, of which4.0 kg is volatile solids, and a corresponding
volume of digested slurry is removed. (This input corresponds roughly to the waste from 20
pigs.) Assuming that a typical reaction in the digestion process is
C12H22O11 + H2O → 6CH4+ 6CO2
and that the reaction takes 7 days to complete, calculate
(i) the volume of gas
(ii) the heat obtainable by combustion of this gas for each day of operation of the
digester
(iii) how much kerosene would have the same calorific value as one day’s biogas?
for part i do we have to use PV=nRT
2 answers
do we have to use mol ratio
Yes, use mole ratios ... You also need to specify atmospheric conditions; i.e., temperature - pressure conditions for calculation of volume values. Then you can use PV = nRT to calculate volumes. One could simply assume STP, but that conglomeration you've described is probably not at zero celcius and 1 atm. You'll also need to provide the 'Heat of Combustion' of Methane & Kerosene; or one could extract table values from the Thermo Props Table.
0 answers