Combustion possibility of low rank Russian peat as a blended fuel of pulverized coal fired power plant

Combustion possibility of Russian peat as a blended fuel of commercial thermal power plant was investigated by thermogravimetric analysis (TGA), drop tube furnace (DTF) and ignition temperature (IT) tester. TGA results showed that the linear regression for the Arrhenius plot to the experimental data is very good, and activation energies for overall combustion of bituminous C & A (Coal & Allied, Australia coal name) and peat are 66.83 and 25.05 kJ/mol, respectively. It was derived that activation energies of 30%, and 50% blends produced through mixing of peat of 30%, and 50% to Design C & A (design criteria coal of 500 M coal fired power plant) are 27.76 and 24.22 kJ/mol in reciprocal proportion to blending ratio. The conversion behavior of the samples observed in DTF was similar to that reflected in TGA. DTF studies showed that the combustion of all blends was also completed at residence time of around 1 s, set temperature range of 1200 °C similar to commercial coal fired plant. Although the peat has the highest conversion than the blends, it was not appropriate as the single pulverized fuel of coal fired plant because its initial deformation (IDT) and ignition temperatures of about 1160 and 240 °C, respectively, were too low to cause the slagging in boiler, and the firing at pulverizer. The IDT and FT of the blends ashes of peat of less than 30% was about 1260 and 1410 °C, respectively, and was not expected to be associated with slagging and fouling in pulverized coal fired systems. The liability of spontaneous combustion of coal samples was increased with increasing the moisture and volatile contents whereas the same of peat was the lowest due to the high volatile content and specific heat (Cp). It was therefore proposed that the combustion of blends of peat with less than 30% was the most appropriate for the prevention of slagging and spontaneous combustion at the pulverized coal fired boilers, and has the excellent combustion efficiency.