CFD Study of a MGT Combustor Supplied with Syngas

The authors discuss in this paper the potential of a micro gas turbine (MGT) combustor when operated under unconventional conditions, in terms of variation in the fuel supplied. The authors' expertise in the field of micro-combustor has addressed, in recent years, some topics of current interest, as the fuelling with gaseous and liquid biofuels and the NOx reduction through the optimization of the combustor.While the previous authors' works were mainly referring to a tubular combustor of a 100kW MGT, the present proposal deals with an annular, reverse flow combustor of a 30 kW MGT. In this case the particular location of both the injectors and of the secondary and diluting holes allows the combustor process to develop under nearly RQL conditions. This is of special interest when supplying the combustion chamber with low LHV fuels. In addition, recent authors' papers have demonstrated that the integration of the MGT with a solar field leads the combustor to require a decreased fuel/air equivalence ratio because of the higher air entry temperature. Under these aspects, the existence of a Rich region within the combustor may be helpful for the early phases of the oxidation process. The pollutant formation rates should be effectively controlled by the secondary (Quick-mix) and diluting (Lean) air flows.The authors' methodology relies on an advanced CFD approach that makes use of a reaction scheme coupled with an accurate study of the turbulent interaction of the reacting species. Extended kinetic mechanisms are also included in the combustion model. A preliminary set-up of the model will be based on the combustion analysis with boundary conditions provided by thermodynamic analysis of the micro-turbine. Several computational examples are discussed, namely: - The analysis of the combustor response with reduced equivalence ratios or changes in the inlet air conditions; -The comparison of combustion efficiency and pollutant production with different fuels