Diesel/syngas co-combustion in a swirl-stabilised gas turbine combustor

Multiphase fuel combustion was carried out in a swirl-stabilised combustor with the aim of expanding the fuel flexibility of the gas turbine for, at least, land-based applications. Improved capability of the gas turbine in this regard will not only augur well for energy security but also could be useful in tackling harmful emissions. In the study, varying amounts of syngas was premixed with air and swirled into a burning diesel spray, the flowrate of which was altered to maintain the same overall heat output at all times. Across the several heat outputs tested, the range of stable flame operation was found to reduce as gas content of fuel mix increased. Moreover, for a combined heat output of 15 kW and a global equivalence ratio of 0.7, a steady increase in flame stability was noted and NOX emissions were found to decrease while CO emissions increased as syngas content in fuel mix increased from 10% to 30%. The increase in flame stability, achieved at the cost of lower heat release rate, was attributed to the changes in reacting flow dynamics evinced by the C2* and CH* species chemiluminescence intensity variation as well as chemical kinetics analysis. The NOX and CO emissions trend was ascribed to decreasing combustion efficiency due to poorer spray quality obtained from the pressure atomiser as liquid flow rate reduces and further worsened by the lower heat release rate and decreasing adiabatic flame temperature as gas ratio of combusted fuel increases.