Research of factors influencing the burnout quality inside a biomass combustion chamber
Keywords:biomass stove, combustion and emissions, efficiency
The essence of the research is to evaluate how the emission concentrations are influenced by structural elements of combustion chambers, such as the inner walls of combustion chambers, as well as the position of the secondary air channel. For purposes of this research the most common type of combustion chamber structure was selected – combustion chamber of primary and secondary air channel system. A wide variety of gaseous compounds (such as carbon monoxide (CO), carbon dioxide (CO2), nitrogen dioxides (NOx), sulphur dioxide (SO2), ammonia (NH3), hydrogen chloride (HCl), hydrogen fluoride (HF), formaldehyde (HCHO), methane (CH4) and other unburned hydrocarbons (CxHy)) was measured using an FTIR spectrometer. Other subjects measures obtained were particulate matter (PM), temperature inside the combustion chamber, smoke flue draught, etc., including chemical composition of the fuel. It was determined, that the burnout quality of the combustion chamber was influenced both by combustion chamber walls of different thermal conductivity and by position of the secondary air intake. It was determined, that use of vermiculite of lower thermal conductivity (V1) reduced the CO concentration by approximately 30 %, and the general concentration of all volatile organic compounds (CxHy) was reduced by half, also resulting in increase of temperature inside the combustion chamber by 33 °C and a 25 % increase of nitrogen oxides (NOx). It was also determined that the height ratio of the combustion chamber and the secondary air intake of 2.3 (X/H2) is the most suitable position for the secondary air intake. This position ensures a carbon monoxide (CO) concentration is 25 % lower than in other positions, and the concentration of all volatile organic compounds (CxHy) is 34 % lower than at height ration of 2.7 (X/H1), and even 44 % lower than at height ratio of 2.