PhD Thesis - Energy Systems Research Unit - University of Strathclyde

3. Make hydrogen via steam reforming
The methane production rate by weight (in kg/hr) is determined using Equation
6.19.
Methane Production Rate (kg/hr) = Biogas x 3610.3 (6.19)
LHV
Where Biogas = Biogas production rate (kW) (from Equation 6.17)
LHV = Lower heating value of methane (kJ/Nm 3 ).
Hydrogen may be made, via the steam reforming of methane, according to the
chemical equation given in section 6.1.3, and the production rate of hydrogen,
by volume (in Nm 3 /hr) is calculated by direct proportion,
Hydrogen Production = 28 x Methane x Percent (6.20)
Rate (Nm 3 /hr) 64 x Density x 100
Where Methane = Methane Production Rate (kg/hr)
Percent = Reaction Completion Percentage
Density = Density of Hydrogen (kg/Nm 3 )
If desired, the remaining production rate of methane (in Nm 3 /hr) can be
calculated by dividing the remaining methane production rate by the density of
methane. To determine the production rates of both of these gases in kW,
multiply the production rate in Nm 3 /hr by the lower heating value of the gas in
kJ/Nm 3 , and divide by 3610.3.
The electricity required to put either or both gases into storage is calculated by
multiplying the amount of gas made (in Nm 3 ) by the electricity required (in
kWh/Nm 3 ). Electricity and heat requirements for the process are calculated by
multiplying the specific energy requirements (kWh/Nm 3 methane) by the
methane production rate (Nm 3 /hr). The total amount of hydrogen produced
(kWh) throughout the simulation period is given along with the final production
rate graphs.
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