PhD Thesis - Energy Systems Research Unit - University of Strathclyde

6 Derived Fuel Production Algorithms
In this chapter the algorithms used to determine the outputs of the various
biomass and waste processing procedures, introduced in Chapter 2, are
described in detail. For each process considered, easily available
manufacturers’ data, feedstock availability, and basic process parameters are
input. The algorithms step through each timestep of the chosen simulation
period in turn, in order to build up a half-hourly profile, for the chosen
simulation period, of the production rate of the derived fuel or fuels (in kg/hr for
solid fuels, litres/hour for liquid fuels and kW for gases). Also produced is a
half-hourly profile of the energy requirements for the process (for electricity,
heat and hot water, in kW). Other significant inputs and outputs are also
considered, and information is given about their overall use or production for the
simulation period being considered.
Due to the complications with the transport demand profiles described in
Chapter 4, any extra demand for transport arising from the processes described
(e.g. transport of feedstock, agricultural vehicle use) should be defined
separately. If a seasonal fuel production profile is defined, and the simulation
being run is for less than a whole year, the user is warned that this may give rise
to misleading results.
6.1 Gasification and Pyrolysis
Although complex models exist to predict the output of gasification and
pyrolysis systems, these require substantial amounts of complex, proprietary,
and not easily available information [1]. A more generic approach has,
therefore, been taken, which is based on available manufacturers’ information
for specific systems with specific feedstocks. As process batches are short
(generally less than 30 minutes) this process is treated as a continuous process.
Only one feedstock type at a time is considered as different feedstocks can give
significantly different results, even with the same equipment [2]. An example of
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