Reduction of nitrogen oxides in flue gases from e.g. lead crystal glass melting furnaces, is achieved by successive injection of fuel gas and oxygen into flue gases

摘要

The flue gas containing nitrogen oxides is led into a duct. At a first location, fuel gas is introduced into it. At a second, downstream of the first, oxygen is supplied to it. An Independent claim is included, pertaining especially, but not exclusively, to a glass-melting furnace. It comprising a melting chamber (12), feeder for the charge (14), extraction point (16) for molten glass and a gas burner (18) directing flames over the melt surface. The flue gas duct (20) has supply points (22, 24) for fuel gas and oxygen respectively. Preferred features: Fuel gas and/or oxygen are/is not preheated. Oxygen introduced, is in the form of air or oxygen-enriched air. The oxidant is introduced where the temperature can cause little or no nitrogen oxidation. Lead is separated in the duct, between the point of fuel gas supply and that of oxygen supply. Flue gases pass through a cooling section (28) before or after addition of oxygen. They pass through a filter (30). The burner is operated with fuel gas, especially natural gas. A mixture of air and fuel gas are supplied to the burner. Additional oxygen is introduced in the furnace near the gas burner. A glass melt surface is heated in a glass furnace. To the surface of the glass melt, a mixture containing nitrate is added. This is at least partially melted by the gas burner. In the corresponding plant, the flue gas duct is a stack. The point of fuel gas supply is 0.1-20 m downstream from the start of the duct. A lead separation location (26) is included. The melting chamber has an electrical heater.