The authors examine in this paper the response of a micro gas turbine (MGT) combustor when supplied
with gaseous fuels from biomass treatment or solid waste pyrolysis or from an anaerobic digestion
process. Actually, a sort of off-design operation is induced by the employment of low calorific value fuels
both in the combustor and in the whole micro turbine system. The objective is to optimize the combustor
behaviour under the point of view of combustion efficiency and pollutant control.
The first part of the paper discusses preliminary pollutant estimation, basing on a non-dimensional,
time-dependent model that solves the kinetic equations for nitric oxides formation in the residence
time domain. The initial conditions are derived from a thermo-fluid dynamic analysis of the MGT system
under several conditions induced by the activation of a recuperator by-pass valve.
In the second part of the paper, a CFD study employs as boundary conditions those obtained from the
thermo-fluid dynamic MGT simulation and it relies on different methods for approaching the fuel
oxidation process. In particular, the partially stirred reactor hypothesis combined with a flamelet model
is able to describe the mechanisms of both primary oxidation and pollutant formation. Several solutions
are also examined in order to improve the combustion efficiency with poor calorific value fuels. The
simultaneous objective of nitric oxide reduction is attained through a proper choice of an alternate
location of the pilot injector aiming at exploiting a sort of internal EGR.