## 2 Experimental Setup and Method
### Experimental Setup
The latter event was recorded automatically by a reduction in the luminous intensity to less than 220 (in the shades of gray) all over the fuel pellet surface (Figure 2b). The systematic errors of determining the times \(t_{d}\) and \(t_{b}\), conditioned by the video recording rate, did not exceed \(\pm\) 0.001 s. The random errors for a set of 7-10 experiments under identical initial conditions were less than 15%. Separate experiments were conducted to establish the concentrations of the main anthropogenic emissions in flue gases from the fuel pellet combustion. A Testo 340 gas analyzer (Testo SE & Co. KGaA, Stuttgart, Germany) was mounted on the setup (Figure 1) in place of the high-speed camera. It comes with four sensors: CO (measuring range 0-10,000 ppm, resolution 1 ppm, accuracy \(\pm\) 10%), NO\({}_{x}\) (measuring range 0-4000 ppm, resolution 1 ppm, accuracy \(\pm\) 5%), O\({}_{2}\) (measuring range 0-25%, resolution 0.01%, accuracy \(\pm\) 0.2%), SO\({}_{2}\) (measuring range 0-5000 ppm, resolution 1 ppm, accuracy \(\pm\) 10%). The CO\({}_{2}\) concentration (measuring range 0-25%, resolution 0.1%, accuracy \(\pm\) 0.2%) was calculated automatically by the results of O\({}_{2}\) concentration measurement. The experimental procedures were similar to those in [40]. Fuel pellets with a total mass of at least 1 g were placed into a pre-heated muffle furnace, using a manipulator. The mass was chosen to fit the gas analyzer specifications and meet a condition of identical heating value, when burning fuel samples with different compositions  
Figure 2: Example of implementing the algorithm of video recording processing with Tema Automotive software for fuel pellet combustion: (**a**) moment of ignition (\(t=t_{d}\)); (**b**) moment of combustion completion (\(t=t_{d}+t_{b}\)). (Table 1). Reliable measurement results necessitated supplying certain minimum volumes of flue gases. These were collected using a gas analyzer probe, inserted into the rotary muffle furnace. Thermal insulator material was used to seal the ceramic tube apertures (Figure 1) to prevent the escape of flue gases during the experiments. Sets of 3-5 experiments were performed under identical initial conditions. Further, the experimental results will be presented as average experimental data values. [PERSON] et al. (2014), established that the higher the temperature, at which ignition and combustion of hydrocarbon fuels occur, the higher the anthropogenic emission concentrations in flue gases. The maximum temperature, generated by the electric muffle furnace being used, is 1000 \({}^{\circ}\)C. In this study, the concentrations of carbon, nitrogen, and sulfur oxides were established from the combustion of fuel pellets per a unit of energy, released at 1000 \({}^{\circ}\)C, which corresponds to the boiler furnace temperature. That means that the gas concentrations obtained will be maximum for the temperature range of 800-1000 \({}^{\circ}\)C, in which the combustion times were investigated. Such approach made it possible to establish differences in the anthropogenic emission concentrations from the combustion of fuel pellets based on coal processing waste when adding various components in the conditions corresponding to the real-scale technological process. The results of the corresponding study will be presented below in the following format: relative emissions, reduced to the allocated identical amount of heating value, when burning different fuel compositions with various mass of fuel samples.