Turbulent diffusion flames of coal derived-hydrogen supplied low calorific value syngas mixtures in a new type of burner: An experimental study

Abstract

This study is concerned with the turbulent diffusion flames of coal derived-hydrogen supplied low calorific value syngases in a new type of burner. In this new type of burner, hydrogen is supplied from the center of the burner to the flame zone in order to improve the combustion performances of these coal-derived syngases. Temperature and emission values have been experimentally performed on axial and radial directions by using thermocouples and a flue gas analyzer through the combustor. All experiments have been studied for a thermal power of 10 kW and an equivalance ratio of ϕ = 0.83. The coal-derived low calorific value syngases have been properly combusted using the new type of burner within the present study. The results show that the maximum temperature measurements of the generator and blast-furnace gases without hydrogen supply were measured and determined to be 863.9 °C and 717.3 °C in the flame zone, respectively. The maximum flame temperatures of these syngases were also determined to be 965.9 °C for generator gas with hydrogen supply (2.5 kW), 1013.1 °C for generator gas with hydrogen supply (5 kW), 883.2 °C for blast-furnace gas with hydrogen supply (2.5 kW) and 898 °C for blast-furnace gas with hydrogen supply (5 kW), respectively. It can be concluded that the flame temperatures of these syngases increase as hydrogen is supplied to the flame zone as expected. It may also be said that the NOX levels of the generator and blast-furnace gases without hydrogen (3 ppm and 2 ppm in the flame region) are very low in comparison to that of the natural gas flame due to their low flame temperatures. However, it is found out that the NOX levels increase rapidly as hydrogen is supplied to the flame. These values were determined to be 85 ppm and 45 ppm under the generator gas and blast-furnace gas with hydrogen supplies (5 kW) combustion conditions. It can also be demonstrated that the presence of CO2 in the fuels (up to 8% by volume) leads to a high volume of CO2 emissions.