The
equations used in the physical simulation model of the gasifier are primarily
stoichiometric calculations of how the biomass is converted through partial
combustion. This will calculate adiabatic temperature and cooling through heat transfer
and through transport of material from the gasifier
and
the heat exchangers in the exhaust gas train. The mass in the bed inventory by
time is given from:
inventory
i,in
i,out m / t = m - m
where mi
,in is the mass input flow of each single component of the composition
vector i= (C, H, O, N, CO2, H2O, NO2, ash) and mi, out is the corresponding
output flow. The change in concentration of each component is given by ci in
the bed inventory: where j are all incoming flows and k all
out-going flows of the inventories. Except the bed inventory we also have one inventory
for the steam system, gas cooling, filter and scrubber. The steam system has
only water and steam components, while the others have the same components as the
bed. The temperature Tinventory in the inventory is
calculated
from the energy balance.
Here enthalpy
is the energy released during combustion and U is the overall heat
transfer coefficient, A is the heat exchanger area and T outside the
temperature at the other side of the heat exchanger surface (steam temperature vs.
exhaust gas temperature). cp, i is the heat capacity for each component .
These physical models have been combined with statistical models where
experimental results in pilot plants
What is Simulation System?
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