Gas turbine combustor for biomass derived LCV gas, a first approach towards fuel-NO_x modelling and experimental validation

The section Thermal Power Engineering of Delft University of Technology operates a 1.5 MW pressurised fluidised bed gasification rig, including a hot gas cleaning unit and a pressurised downscaled Alstom gas turbines combustor. Regarding the combustion of low calorific value (LCV) gas, experiments are done to validate models describing turbulent steady state combustion. In this paper biomass derived LCV gas combustion experiments are described. The heating value of the gas was in the range of 2.5-4 MJ/m_n³ and the process pressure was 3-8 bar. In all experiments, good combustion efficiency was observed. NO_x formed, resulted from NH₃ fuel_nitrogen conversion to NO_x was in the range of 10-60%. The combustor was modelled using the CFD program Fluent. As chemistry models, the chemical equilibrium, laminar flamelet and reaction progress variable model were applied. Turbulence closure Reynolds stress and K-ε were used in the calculations. The fate of fuel_nitrogen conversion to NO_x was one of the main issues studied. The agreement between models and experiment was good for the experiments performed in the higher-pressure range.