## 3 Results and Discussion  
Continuous gas analysis was performed under the conditions of heating the reactor (with a fuel sample) with hot air in the temperature range from 293 K to 873 K. In the figures, the blue line shows the temperature inside the reactor, measured continuously throughout the experiment, and the red line shows the change in the concentration of the analyzed gas. Figures 2-5 show the typical results of recording the composition of the gaseous products of thermal decomposition of D-grade coal and wood, as well as the mixed fuels prepared on their basis. It was experimentally established that the proportion of sulfur oxides decreased by 95.8% at a wood component concentration of 50% in a mixed fuel based on metaligntous coal. Analysis of Figure 2 allows to establish a significant decrease in the concentration of sulfur oxides in the gaseous products of the pyrolysis of mixed fuels by increasing the proportion of sawdust relative to the concentration of sulfur oxides in the flue gas of the initial coal. It was also found that a reduction in the sulfur oxides concentration is not additive, even in the absence of bound sulfur in the composition of pine sawdust. The obtained data confirm the ultimate analysis results of the ash composition of the studied fuels and their mixtures. An increase in the proportion of the wood component by 25%  
Figure 1: Layout of the experimental stand for determining the composition of the gaseous products of a fuel thermal decomposition. 1—fuel sample; 2—reactor with fuel sample; 3—air heater; 4—gas analyzer; 5—coarse filter; 6—channel for supplying gaseous products of fuels thermal decomposition to gas analyzer with filtration system; 7—thermocouple; 8—thermocouple signal converter; 9—communication line between thermocouple and signal converter; 10—communication line between thermocouple signal converter and laptop; 11—laptop; 12—communication line between gas analyzer and laptop; 13—output channel for gaseous products of thermal decomposition of fuel samples; 14—ventilation shaft. in the mixture with coal also leads to a significant (93%) decrease in the concentration of sulfur oxides. Figure 3 shows the results of determining the concentrations of nitrogen oxides in the gaseous pyrolysis products of metaliginitous coal, wood, and mixed fuels based on them. Figure 2: _Cont_. in the share of biomass by 25% leads to an increase in the share of nitrogen oxides by 7% relative to the values obtained by pyrolysis of homogeneous D-grade coal. At the same time, the concentration of nitrogen oxides decreases by 11.3% with an increase in the proportion of the wood component to 50% relative to the concentration of the same oxides during pyrolysis of homogeneous coal. Analysis of the gaseous products of mixed fuels thermal decomposition showed that the yield of nitrogen oxides significantly depends on the temperature conditions of the thermal decomposition of the latter. Figure 3: _Cont._  
The results of recording the concentration of carbon dioxide in the gaseous pyrolysis products of mixed fuels based on D-grade coal and wood are shown in Figure 4.  
Analysis of the composition of the gaseous thermal decomposition products (Figure 4) of mixed fuels allowed us to distinguish two stages of carbon dioxide formation. Intensive thermal decomposition of the wood component begins at the first stage (small peak). The second peak (the main peak) corresponds to the maximum rates of thermal decomposition of both fuel components (coal and wood). It was established that an increase in the concen  
Figure 3: Changes in the concentration of nitrogen oxides in the gaseous products of thermal decomposition of mixed fuels based on D-grade coal and wood with a change in the proportion of the latter in the mixture from 10% to 50%: (**a**) metalignitous coal 100%; (**b**) metalignitous coal 90%/wood waste 10%; (**c**) metalignitous coal 75%/wood waste 25%; (**d**) metalignitous coal 50%/wood waste 50%.