Comparison of emissions from smokeless coal combustion in a household heating boiler used in Central Europe

Abstract

The objective of this work was to evaluate the relationship between the fuel quality and the gaseous and particulate pollutant emissions generated from a hot-water boiler during the combustion of different types of innovative processed fuels: smokeless coal, smokeless briquettes 1–3, smokeless pellets and unprocessed hard coal. The aim of our research was to prove the presumption that smokeless processed coals produce less gaseous and particulate emissions. By using modern fuels in already used and manufactured older boilers, there is a possibility to significantly reduce emissions of organic gaseous compounds (OGC) and polycyclic aromatic hydrocarbons (PAHs). The emission situation in the heating season can be significantly improved even without costly production, and thus consumption of natural resources and energy, and installation of modern boilers. Physical and chemical characterization of solid-fuel samples, including determination of moisture content, ash, volatile organic content, calorific value and elemental composition analysis, were performed. Fuels were burned in one type of hot-water boiler class 1 according to EN 303-5 to determine the impact of applied fuel types on pollutant emissions. The pollutant emissions were characterized by the contents of gaseous components: nitrogen oxides NOx, sulfur dioxide SO2, carbon monoxide CO, carbon dioxide CO2, organic gaseous compounds OGC and particle components: total suspended particles TSP, particulate matter less than 2.5 µm and 10 µm (PM2.5 and PM10, respectively) and polycyclic aromatic hydrocarbons PAHs in both phases. The emission factors from six types of fuel were compared with applicable European standards. The lowest NOx content was observed for smokeless briquette 1, while the lowest SO2 content was observed for smokeless pellets. The emission of CO was at a similarly low level of 200 g/kg for smokeless briquette 1, smokeless briquette 2 and hard coal. Gaseous and pollutant emissions described by PM2.5 and TSP were observed to be the lowest for smokeless coal, smokeless briquette 1 and smokeless briquette 2.