# Comparative Analysis of Partially Renewable Composite Fuels Based on Peat, Lignite and Plant Oil
## 2 Materials and Methods  
The compositions of peat and rapeseed oil (P + RO) were prepared using the peat from the Sukhovskoe peat deposit of the Tomsk Region, Russian Federation [27]. B2-class lignite from one of the deposits of the Krasnoyarsk Region, Russian Federation was used to prepare the compositions of lignite and rapeseed oil (L + RO). The properties of solid components are summarized in Table 1. One can see that these fuels have essential differences in moisture and ash content as well as in the amount of volatiles and in the chemical composition. The heat capacity and calorific value of lignite are a bit higher than those of peat, whereas the heat conductivity and thermal conductivity of lignite are lower. The technical grade rapeseed oil produced in the Tomsk Region, Russian Federation was used as a renewable component of the compositions. The properties of the RO are shown in Table 2. The data were obtained from the specification of the oil manufacturer that correlated well with earlier published data [28]. The solid components (peat and lignite) were milled by a rotary mill and riddled through calibrated sieves. Thus, the average particle size was about 100 um. The obtained powder was mixed with RO according to the required component ratio. The resulting composition was mechanically mixed by a rotary homogeniser for 10 min. Such mixtures keep good enough homogeneity, even in millimeter size droplets. The sample weight for the thermogravimetric analysis (TGA) investigations was about 5-6 mg. The sample weight for calorimetry was about 0.6 g. The sample weight for the allothermal gasification was about 0.5-1 g.  
TGA estimates the most optimal thermal regime for the thermochemical conversion of the fuel under study. It was performed using an SDT Q600 analyzer. The thermogravimetric measurements were performed at an air feeding rate of about 2 mL/min and a temperature increase rate of 10 K/min. Calorimetry was performed with an ABK-1V Bomb Calorimeter. The gasification of composite fuel was carried out using an original technique [9; 22], with samples exposed to radiative heating by a focused flow of visible light (see Figure 1). The 500 W halogenic lamp provided a white light flow with a power of up to 15 W. Focusing the flow with a parabolic mirror to the spot about 1.3 mm in diameter allowed the intensity of the radiation of up to 1 kW/cm\({}^{2}\) (which was controlled by a thermoelectric power meter). The light flow intensity was adjusted by varying the electrical current in the lamp circuit. \begin{table}
\begin{tabular}{c c c} \hline
**Property** & **Lignite** & **Peat** \\ \hline Moisture, wt\% & 14.11 & 38.2 \\ Ash content, A\({}_{\text{d}}\), \% & 4.12 & 31.5 \\ Volatile content, V, \% (daf) & 47.63 & 71.5 \\ \hline \multicolumn{3}{c}{Chemical composition, wt\% (_daf_)} \\ \hline C & 73.25 & 51.03 \\ H & 6.516 & 6.01 \\ N & 0.79 & 4.62 \\ S & 0.435 & 0.15 \\ O & 18.99 & 38.19 \\ \hline \multicolumn{3}{c}{Thermal properties} \\ \hline Heat conductivity, \(\lambda\), W/(m\(\cdot\)K) & 0.15 & 0.22 \\ Heat capacity, C\({}_{\text{p}}\), kJ/(kg\(\cdot\)K) & 2.09 & 1.77 \\ Thermal diffusivity, a, cm\({}^{2}\)/s & 0.007 & 0.01 \\ High combustion heat, Q\({}^{\text{g}}\), V, MJ/kg & 22.91 & 19.4 \\ \hline \end{tabular}
\end{table} 
Table 1: Properties of solid components of the fuel composition [29; 30]. The fuel sample was placed inside a chamber with an optical window on the top. The radiative heating of the sample was carried out through this window with a simultaneous measurement of the temperature of fuel surface by an Optris Pi 1 M thermal imaging system. The emitted gases were pumped out from chamber through a fitting at the sidewall of the cuvette by a gas analyzer pump. The oxygen income went through the slit in the opposite wall of the chamber. The performance of the pump of gas analyzer was about 4 mL/s. The chemical composition of the gases produced was analyzed using a Test-1 gas analyzer.