Emissions from wood and peat-fired heating plants

The use of wood and peat in small scale boilers (10 kW—10 MW), has increased because the price of oil has advanced. Further the acidification of environment caused by emissions of sulphur oxides has increased. Wood and peat with their small sulphur content are good fuels in this respect.Emissions of sulphur dioxide, hydrocarbons and nitrogen oxides are not too high during good combustion process. If wood and peat is burnt in plants (1—10 MW), emissions of hydrocarbon and polynuclear aromatic hydrocarbons (PAH) are low. High emissions of tar, total hydrocarbon and PAH have been measured from combustion of wood and peat in small furnaces. The development of boilers to correspond better the properties of the fuels used may decrease significantly these emissions. Also the complete control of the whole combustion process helps to the emissions.The dust emissions of small plants can be decreased with flue gas collectors. The multicyclone has generally been used as the collector in this scale. Emissions of some metals depend on the fly ash separation efficiency.