Experimental investigation on syngas reburning process in a gaseous fuel firing semi-idustrial combustion chamber

•The reburning technology was tested for syngas fuels with high content of ammonia.•The reduction of NO emission for low and medium LHV syngas fuels was observed.•The amount of primary air plays a key role in fuel NO formation in ZVC technology.•High thermal NO was measured for high calorific syngas as a main/reburning fuels.•Extremely low conversion factor (CF) of ammonia to NO was received. The article presents the results of the experimental investigation of nitric oxides reduction with a reburning process using syngas fuels in semi-industrial gas fired combustion chamber. The studies included the influence of different chemical properties of syngas fuels, on the total of NO and CO emission. The properties of syngas fuels included low calorific value (from 3.43 to 17.2 MJ/Nm3), amount of fuel-bound nitrogen and the share of reburning fuel. The tests have been carried out for two main fuels methane and synthesis gas in semi-industrial combustion chamber. It has been reported that reduction of NO by synthesis reburning fuels reached level up to 80% for low and 45% for medium calorific fuels in case of methane as primary fuel. The high calorific value of synthesis fuel (17.2 MJ/Nm3) introduced to the combustion chamber as a reburning agent caused an increase of NO formation especially in case of low primary nitric oxide emission (an increase of 27% – 60 ppmv). The application of reburning process to the Zonal Volumetric Combustion (ZVC) technology allowed to achieve around 43% reduction of nitric oxide emission in case of medium calorific syngas and excess of primary air value equal to 0.5. For the same fuel, with the excess of primary air equal to 0.1 (proffered by ZVC) the decrease of NO was lower, only up to 14%. The highest reduction was observed for low calorific syngas with the highest concentration of ammonia (more than 60% reduction).