This paper presents possibilities for of numerical modelling of biomass combustion in a commercially available boiler. A sample of biomass was tested with respect to its physical and chemical properties. Thermogravimetry studies of biomass were carried out. Computer simulation makes it possible to analyse complex phenomena which are otherwise difficult to observe. The aim of this work was to model biomass combustion to predict the amount of pollutants generated (NOx, CO, SO2) in the exhaust gases coming out from boilers The calculations were made using the CHEMKIN program. Results of calculations were performed taking into account the influence of temperature, pressure and residence time.

The paper aims to confirm the syngas application as a reburning fuel to reduce e.g. NO emission during natural gas combustion. The main aim of this modelling work was to predict pollutants generated in the exhaust gases and to indicate the influence of the syngas on the natural gas combustion process. The effect of residence time of fuel-air mixture was also been performed. Calculations were made with CHEMIKN-PRO for reburning process using syngas. The boundary conditions of the reburning process were based on experimental investigations. The addition of 5, 10, 15 and 19% of reburning fuel into natural gas combustion was studied. The effects of 0.001 to 10 s of residence time and the addition of 5, 10, and 15% of syngas on combustion products were determined. The performed numerical tests confirmed that co-combustion of the natural gas with syngas (obtained from sewage sludge gasification) in the reburning process is an efficient method of NOx reduction by c.a. 50%. Syngas produced from sewage sludge can be utilised as a reburning fuel.