Cadorin Margherita - ENDIF, Engineering Department in Ferrara (Italy)
Vaccari Anna - ENDIF, Engineering Department in Ferrara (Italy)
Pinelli Michele - ENDIF, Engineering Department in Ferrara (Italy) |
The ever-increasing energy demand and the need to reduce polluting emissions and greenhouse gases in recent years has driven attention towards technologies to produce thermal and electrical energy which cut down emissions, and towards fuels derived from renewable and alternative resources. Among these technologies, there are micro gas turbines, i.e. small size machines usually fed by natural gas, for distributed electricity generation, that can be fed by gas fuels with low heat of combustion, resulting from pyrolysis and/or gasification processes: they are in general synthesis gases, derived from biomasses of various types.
Synthesis gases for small size energy systems, such as the ones for the distributed micro combined heat and power, have not yet reached a technology maturity which could promote their diffusion into the market. For this reason, it is relevant to proceed with research activities, because this allows these technologies to achieve performance and reliability that are typical of established technologies, which rely on traditional fuels.
Fueling with synthesis gas instead of natural gas can generate various problems due to the different fuel properties: lighting difficulty, combustion instability, increase of polluting emissions, and fouling problems. The numerical thermo/fluid-dynamics analysis of the combustion process inside the chamber represents a powerful tool to use for the identification of problems in the microturbines, deriving from fuels with a low rate of heat of combustion, and to suggest possible changes for the chamber design or other combustion management modalities.
This study describes the numerical analysis of the combustion in a microturbine combustor with a nominal power of 100 kWel, feeded by a synthesis gas, derived from a biomass gasification process. The performed analyses concern the combustor performance in different operating conditions, i. e. the fuel distribution between two feeding lines and the amount of the air sucked in by the compressor. The aim of the analyses was to identify the main features of the combustion phenomenon, in case of feeding by syngas of different compositions, compared to the ones of a traditional fuel, such as the natural gas, the most suitable gas for the combustor. |