REQUIREMENTS FOR LOW-EMISSION WOOD FIRINGS

An ecological combustion of wood and wood residues requires an efficient burn out of the combustible gases and an efficient precipitation of the particles. To reach a complete burn out the combustion is divided in the gasification with primary air and the burn out of the gases with secondary air. If these conditions are met the emissions of carbon monoxide and hydrocarbons can be diminued effectively. On the contrary the emissions of nitric oxides cannot be diminued since they origin mainly from the fuel bound nitrogen. It is necessary to develop low-NO(x) wood firings due to staged combustion or other new technologies. For large scale plants the use of processes to reduce nitric oxides in the flue gas have to be examined.