Apparatus for Treating Exhaust Gas of an Internal Combustion Engine

Abstract

An apparatus for treating exhaust gas of an internal combustion engine, includes a feed conduit feeding aqueous solution, a hydrolysis catalytic converter connected to the feed conduit and an SCR catalytic converter through which exhaust gas flows. A rod-shaped heating element heats at least parts of the feed conduit and/or hydrolysis catalytic converter. The apparatus provides a compact structure of a feed conduit heated by a rod-shaped element and a corresponding hydrolysis catalytic converter, with which an aqueous solution containing urea can be evaporated and then hydrolyzed to a gas stream containing ammonia. This gas stream serves as a reducing agent in the SCR process. The compact configuration allows installation in very confined space conditions. The hydrolysis catalytic converter, through which exhaust gas does not flow, permits the volume of the hydrolysis catalytic converter to be decisively reduced, since significantly smaller mass flows of gas need to be hydrolyzed therein.

1 . An apparatus for treating exhaust gas of an internal combustion engine, the apparatus comprising:
 at least one feed conduit for feeding an aqueous solution;   a hydrolysis catalytic converter connected to said feed conduit;   an SCR catalytic converter through which exhaust gas can flow; and   at least one rod-shaped heating element for heating at least one of:
 a) at least parts of said feed conduit, or 
 b) said hydrolysis catalytic converter. 
   
   
   
       2 . The apparatus according to  claim 1 , wherein said at least one feed conduit has an inner surface with a mean surface roughness of 8 to 12 microns. 
   
   
       3 . The apparatus according to  claim 1 , wherein said at least one feed conduit is formed of a material having a thermal conductivity of more than 200 W/(m K) (Watts per meter and Kelvin). 
   
   
       4 . The apparatus according to  claim 1 , wherein said at least one feed conduit is formed of a material including aluminum. 
   
   
       5 . The apparatus according to  claim 1 , wherein at least one of:
 a) at least parts of said at least one feed conduit, or   b) said hydrolysis catalytic converter,   
     is disposed around said at least one rod-shaped heating element. 
   
   
       6 . The apparatus according to  claim 1 , wherein said at least one heating element has a tubular casing, and said at least one feed conduit has at least one channel formed at least partially by said tubular casing. 
   
   
       7 . The apparatus according to  claim 6 , wherein said at least one channel is disposed in said tubular casing. 
   
   
       8 . The apparatus according to  claim 6 , which further comprises a sleeve disposed coaxially with said at least one heating element, said at least one channel being delimited inwardly by said tubular casing and outwardly by said sleeve. 
   
   
       9 . The apparatus according to  claim 1 , which further comprises a sleeve disposed outside said at least one heating element, said sleeve being at least partially in thermal contact with at least one of:
 a) at least parts of said at least one feed conduit, or   b) said hydrolysis catalytic converter.   
   
   
       10 . The apparatus according to  claim 9 , wherein said sleeve is heatable. 
   
   
       11 . The apparatus according to  claim 1 , wherein said hydrolysis catalytic converter includes an inner tubular casing, an outer tubular casing, and an annular honeycomb body having cavities through which a fluid can flow, said cavities being disposed between said inner and outer tubular casings. 
   
   
       12 . The apparatus according to  claim 11 , wherein said inner tubular casing of said annular honeycomb body is at least partially in thermal contact with said at least one rod-shaped heating element.