PhD Thesis - Energy Systems Research Unit - University of Strathclyde

direct proportion, and the weight of extra CO2 required is determined. The
completion percentage must, again, be applied.
The production rate of methanol in litres/hr is calculated by dividing the
production rate (in kg/hr) by the density of methanol (in kg/m 3 ), and multiplying
by 1000. The production rate of any remaining hydrogen and methane (in kW)
is calculated using Equation 6.11, and the electricity required to put either or
both gases into storage, if desired, is calculated using Equation 6.12.
Again, the total amount of methanol, hydrogen and methane produced, and the
amount of extra carbon dioxide used throughout the simulation period, is given
along with the final production rate graphs. Any excess energy requirements
arising from this process may be added to the overall process energy
requirements considered in section 6.1.2.
6.1.4 General Comments
Many pyrolysis and gasification systems are linked directly with combined heat
and power (CHP) production plants as the waste heat that these produce can be
used for the fuel production process, allowing a high degree of process
integration, maximising efficiency [2]. As it may be difficult to separate the
process outputs and energy requirements of such plant, it is also possible to
model their operation using the generic engine/turbine model described in
Chapter 5. An example of the definition window for such a system is shown in
Appendix 1, Figure A1.36. In order to do this, the rated electrical output, heat to
electricity ratio, and efficiency at partial load must be known. Direct wood
gasifier stoves may also be modelled as heating systems.
Some or all of the required process heat and electricity is often derived from a
portion of the output fuel. If this is the case, these outputs, and the
corresponding energy demands, can be subtracted from the totals input into the
simulation.
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