Exhaust gas systems utilizing pre-turbine reductant injectors and methods for controlling the same

Abstract

Exhaust gas systems and method for controlling the same are provided. Systems include a hydrolysis catalyst device (HCD) in fluid communication with an exhaust gas conduit, a turbocharger turbine disposed downstream from the HCD and in fluid communication therewith via the conduit, a selective catalytic reduction device (SCR) disposed downstream from the turbine and in fluid communication therewith via the conduit; and a reductant injector configured to inject reductant into the conduit upstream from the HCD. The HCD can comprise TiO2, V2O5, A12O3, and SiO2. Methods can include injecting reductant upstream from turbine, such as while the SCR is below a NOx light-off temperature and/or a reductant decomposition temperature. The system can further include a second reductant injector configured to inject reductant into the conduit at a second injection location downstream from the turbine and upstream from the SCR, and the method can include injecting reductant via the second injector.

What is claimed is: 
     
         1 . An exhaust gas system comprising:
 a hydrolysis catalyst device (HCD) in fluid communication with an exhaust gas conduit   a turbocharger turbine disposed downstream from the HCD and in fluid communication therewith via the exhaust gas conduit;   a selective catalytic reduction device (SCR) disposed downstream from the turbocharger turbine and in fluid communication therewith via the exhaust gas conduit; and   a reductant injector configured to inject reductant into the exhaust gas conduit upstream from the HCD.   
     
     
         2 . The exhaust gas system of  claim 1 , wherein the HCD comprises one or more of TiO 2 , V 2 O 5 , Al 2 O 3 , and SiO 2 . 
     
     
         3 . The exhaust gas system of  claim 1 , wherein the HCD comprises one or more of TiO 2  and V 2 O 5 . 
     
     
         4 . The exhaust gas system of  claim 1 , wherein the reductant comprises urea and/or a nitrogen-rich substance capable of decomposing into ammonia. 
     
     
         5 . The exhaust gas system of  claim 1 , wherein a decomposition temperature threshold of the reductant is higher than a light-off temperature of the SCR. 
     
     
         6 . The exhaust gas system of  claim 1 , wherein the SCR is close-coupled to the turbocharger turbine. 
     
     
         7 . An internal combustion engine (ICE) exhaust gas system comprising:
 an ICE configured to emit exhaust gas to an exhaust gas conduit;   a turbocharger turbine disposed downstream from the ICE and in fluid communication therewith via the exhaust gas conduit;   a selective catalytic reduction device (SCR) disposed downstream from the turbocharger turbine and in fluid communication therewith via the exhaust gas conduit; and   a first reductant injector configured to inject reductant into the exhaust gas conduit at a first injection location upstream from the turbocharger turbine.   
     
     
         8 . The ICE exhaust gas system of  claim 7 , wherein a decomposition temperature threshold of the reductant is higher than a light-off temperature of the SCR. 
     
     
         9 . The ICE exhaust gas system of  claim 7 , further comprising a hydrolysis catalyst device (HCD) in fluid communication with the exhaust gas conduit and disposed between the reductant injection location and the turbocharger turbine. 
     
     
         10 . The ICE exhaust gas system of  claim 9 , wherein the HCD comprises one or more of TiO 2 , V 2 O 5 , Al 2 O 3 , and SiO 2 . 
     
     
         11 . The ICE exhaust gas system of  claim 7 , further comprising a second reductant injector configured to inject reductant into the exhaust gas conduit at a second injection location downstream from the turbocharger turbine and upstream from the SCR. 
     
     
         12 . The ICE exhaust gas system of  claim 7 , wherein the ICE comprises a diesel ICE. 
     
     
         13 . The ICE exhaust gas system of  claim 7 , wherein the reductant comprises urea and/or a nitrogen-rich substance capable of decomposing into ammonia. 
     
     
         14 . The ICE exhaust gas system of  claim 7 , further comprising an oxidation catalyst device in fluid communication with the exhaust gas conduit and disposed downstream from the SCR. 
     
     
         15 . A method for controlling an internal combustion engine (ICE) exhaust gas system, wherein the system includes an ICE configured to emit exhaust gas to an exhaust gas conduit, a turbocharger turbine disposed downstream from the ICE and in fluid communication therewith via the exhaust gas conduit, a selective catalytic reduction device (SCR) disposed downstream from the turbocharger turbine and in fluid communication therewith via the exhaust gas conduit, and a first reductant injector configured to inject reductant into the exhaust gas conduit at a first injection location upstream from the turbocharger turbine, the method comprising:
 injecting reductant upstream from turbocharger turbine.   
     
     
         16 . The method of  claim 15 , wherein injecting reductant upstream from the turbocharger turbine occurs while the SCR is below a NOx light-off temperature and/or a reductant decomposition temperature threshold. 
     
     
         17 . The method of  claim 15 , further comprising subsequently ceasing injection of reductant upstream from the turbocharger turbine after the SCR achieves a NOx light-off temperature and/or a reductant decomposition temperature threshold. 
     
     
         18 . The method of  claim 15 , wherein the system further comprises a second reductant injector configured to inject reductant into the exhaust gas conduit at a second injection location downstream from the turbocharger turbine and upstream from the SCR, and the method further comprises injecting reductant via the second injector after the SCR achieves a NOx light-off temperature and/or a reductant decomposition temperature threshold. 
     
     
         19 . The system of  claim 15 , wherein a decomposition temperature threshold of the reductant is higher than a light-off temperature of the SCR. 
     
     
         20 . The system of  claim 15 , wherein the reductant comprises urea and/or a nitrogen-rich substance capable of decomposing into ammonia.