Procedure and plant for treating gases released from the incineration of household waste

摘要

The oxidised nitrogen concentration of a gaseous effluent produced during incineration of domestic waste is reduced by a selective non-catalytic reduction process. Sludges produced during municipal waste water treatment or during industrial manufacturing processes are used as functional chemical agent. Domestic waste (OM) is introduced (1) to a furnace (2) and burnt. Ash is removed form the base of thr furnace (3) and gas (EG) passes up a tower (5) at a temperature of 850-1000 deg.C, where the sludge (CC) is add (25). Sludge (CC) is introduced into the gas stream leaving the furnace (2) by one or more sprays (41) which face downwards, towards the furnace. Compressed air (50) is also fed to the sprays along with water (58) to adjust the solids concentration of the sludge and ammonia (59) at a concentration of about 2% in the form of urea, primary or secondary amines or ammonia. The sludge is adjusted to contain about 20% solids, or which just over half are organic. Sludge may be sprayed from a point, line or surface at one or more positions in the tower (4). Compressed air is used to help form the droplets. The sprays can be easily withdrawn from the tower by moving horizontally on tracks. When outside the tower they can be cleaned with water. After leaving the tower the gas stream is subjected to heating, electrofiltration, a heat exchange condenser, cooling and removal of ash and fine particles.