Flue gas purification plant

Abstract

A plant for purifying the flue gases from a furnace, in particular from a rotary cement kiln, has at least one selective reduction catalyst for reducing nitrogen oxides present in the flue gas, optionally introduction of a reducing agent and a dust filter or precipitation system. The dust precipitation system is formed by at least one first and one second filter apparatus. The reduction catalyst is arranged between the first and second filter apparatuses.

1 - 8 . (canceled) 
     
     
         9 . A plant for purifying flue gas from a furnace, the plant comprising:
 at least one selective reduction catalytic converter for reducing nitrogen oxides present in the flue gas and/or a catalytic converter for reducing carbon monoxide, hydrocarbons, and/or ammonia;   an optional reducing-agent feed device; and   a dust separation device formed of at least one first filter device and at least one second filter device, and having said selective reduction catalytic converter disposed between said first and second filter devices.   
     
     
         10 . The plant according to  claim 9 , wherein the furnace is a cement rotary kiln. 
     
     
         11 . The plant according to  claim 9 , wherein said first filter device is disposed substantially immediately following the furnace or a heat exchanger unit, in a flow direction of the flue gas. 
     
     
         12 . The plant according to  claim 9 , which further comprises a desulfurization plant disposed between said first filter device and the furnace, in a flow direction of the flue gas. 
     
     
         13 . The plant according to  claim 9 , which further comprises a heat exchanger unit connected immediately following the furnace in a flow direction of the flue gas, and a desulfurization plant disposed between said heat exchanger unit and said first filter device in the flow direction of the flue gas. 
     
     
         14 . The plant according to  claim 9 , wherein said first filter device is an electric filter. 
     
     
         15 . The plant according to  claim 9 , which further comprises at least one raw material drying apparatus connected between said catalytic device and said second filter device, in a flow direction of the flue gas. 
     
     
         16 . A method of purifying flue gas generated in a furnace, which comprises:
 providing the plant according to  claim 9  connected to the furnace;   guiding the flue gas from the furnace to the first filter device of the dust separation device;   subsequently conducting the flue gas into contact with a selective reduction catalytic converter for selective catalytic reduction of nitrogen oxides by a reducing agent and/or at least one catalytic converter for reducing carbon monoxide, hydrocarbons, and/or ammonia; and   subsequently subjecting the flue gas to a fine-dust purification by filtering dust from the flue gas in the second filter device of the dust separation device.   
     
     
         17 . The method according to  claim 16 , wherein the flue gas is generated in a cement rotary kiln. 
     
     
         18 . The method according to  claim 16 , which comprises reducing a dust content of the flue gas in the first filter device to a maximum dust content of 30 g/m 3 N before the flue gas is conducted to the catalytic device. 
     
     
         19 . The method according to  claim 18 , which comprises reducing a dust content of the flue gas in the first filter device to a maximum dust content of 3 g/m 3 N. 
     
     
         20 . The method according to  claim 19 , which comprises reducing a dust content of the flue gas in the first filter device to a maximum dust content of 2.5 g/m 3 N. 
     
     
         21 . The method according to  claim 16 , which comprises carrying out a first dust separation in the first filter device at a temperature of the flue gas of at least 250° C. 
     
     
         22 . A method of purifying flue gas generated in a furnace, which comprises:
 guiding the flue gas from the furnace to a first filter device of a dust separation device and subjecting the flue gas to a first dust separation;   subsequently conducting the flue gas for contact with a selective reduction catalytic converter for selective catalytic reduction of nitrogen oxides with a reducing agent and/or a catalytic converter for the reduction of carbon monoxide, hydrocarbons, and/or ammonia; and   subsequently, following the catalytic reduction, subjecting the flue gas to a fine-dust purification in a second filter device of the dust separation device.