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Abstract. The aim of the article is the offer of control of environmentally undesirable products of coal and biomass co-firing with the use of numerical methods. The article analyzes the impact of co-combustion of coal and pellets made of sunflower husk in power plant boiler with a capacity of 125 MW on the composition of the flue gas. Based on the data obtained from a real object, in particular: the combustion temperature, the reagent fluxes, i.e. air, coal and biomass, as well as the elemental composition of the fuels supplied into the boiler, the initial conditions were formulated and the computer simulations were made, leading to determining the chemical composition of flue gas. Numerical calculations were performed using the latest version of CHEMKIN-PRO software. Chemical mechanism was developed by the Italian group The CRECK Modeling and it included 134 compounds and 4169 chemical reactions, including reactions of forming chlorine compounds. Additionally, the impact of selected parameters, e.g. temperature on the chemical composition changes of the combustion products was analyzed. Developed calculation model with the implemented chemical mechanism was verified by data collected from the real conditions, leading to increasing the reliability of the results. The calculations showed that the most important influence on the composition of the flue gas from the co-firing process of coal with sunflower husk has a composition of biomass. It should be emphasized that the results of computer simulations obtained by the authors have an useful aspect and can be applied in practice, especially to the analysis of the mechanism of chloride corrosion which is possible to occur due to the chlorine content in the biomass. They may also be useful for evaluating the unburned hydrocarbons produced by combustion of rich mixtures (λ < 1.0).

This paper contains experimental research of NOx reduction in the combustion process with the primary methods, which were applied separately and in combined systems. In addition, the pulsation disturbance (PD) was applied, that is the gas stream was disturbed to increase the intensity of reagents mixing. An experimental stand was built to determine an influence of the following primary methods: air staging, reburning and flue gas recirculation on a reduction of NOx concentration. Experiments were carried out in three combinations: air staging with reburning, reburning with recirculation and air staging with recirculation. In all these cases, the PD was simultaneously applied. Researches were carried out in a quartz combustion chamber with laboratory equipment enabled to measure all the thermal and the chemical parameters of the process. The simultaneous application of primary methods causes additional increase in NOx reduction in certain systems.