The Effect of Firewood Moisture Content on the Atmospheric Thermal Load by Flue Gases Emitted by a Boiler

In this paper, we present an analysis on the effect of the moisture content of firewood on the atmospheric thermal load created by the heating of flue gases with temperatures of t_fg = 120–200 °C, emitted by a boiler when wood with moisture content of W = 10%–60% is combusted. The load of the atmosphere created by the heat of the flue gases with temperatures of t_s = 120 °C from the boiler, where dried wood with the moisture content of W = 10% is combusted, is Q = 9.2 MJ·GJ⁻¹. The atmospheric thermal load caused by flue gases with the temperature of t_s = 200 °C, resulting from the combustion process of wet firewood with a moisture content of W = 60%, is 3.8 times higher compared with the above-mentioned conditions. The heating of water vapor from the evaporated water occurring in combusted wood, as well as the heat of the heated nitrogen and unoxidized oxygen in the combustion air delivered to the furnace of a firewood boiler, are considered to be reasons for the increasing atmospheric thermal load caused by the heating of flue gases, resulting from the combustion of wood with higher moisture content.