System and method for the on-board production of reductants

Abstract

A system is provided for the on-board production of reductants. The system comprises a fuel tank adapted to directly or indirectly supply a first fuel stream and a second fuel stream. An engine is in fluid communication with the fuel tank, and is configured to receive the first fuel stream and create an exhaust stream. The system further includes an emission treatment unit to treat the exhaust stream. A fuel conversion unit is configured to receive the second fuel stream, and also receive a stream comprising oxygen to partially oxidize at least a portion of the second fuel stream thereby forming reductants. In addition, the fuel conversion unit is configured to supply a reductant stream comprising the reductants to the exhaust stream. The invention further provides a method for the on-board production of reductants including supplying a first fuel stream to an engine, wherein the engine is configured to create an exhaust stream. A second fuel stream and a stream comprising oxygen are supplied to a fuel conversion unit. At least a portion of the second fuel stream is partially oxidized in the fuel conversion unit to form reductants, and a reductant stream comprising the reductants is supplied to the exhaust stream. The selective catalytic reduction of NOx present in the exhaust stream is performed.

1 . A system for the on-board production of reductants comprising:
 a fuel tank adapted to directly or indirectly supply a first fuel stream and a second fuel stream;   an engine in fluid communication with the fuel tank, wherein the engine is configured to receive the first fuel stream and create an exhaust stream;   an emission treatment unit to treat the exhaust stream;   a fuel conversion unit configured to receive the second fuel stream, and also receive a stream comprising oxygen to partially oxidize at least a portion of the second fuel stream thereby forming reductants, the fuel conversion unit also configured to supply a reductant stream comprising the reductants to the exhaust stream.   
   
   
       2 . The system of  claim 1 , further comprising:
 a first fuel pump adapted to pump the first fuel stream from the fuel tank to the engine.   
   
   
       3 . The system of  claim 1 , further comprising:
 a second fuel controller that receives a signal representing a concentration of NOx in a treated exhaust stream exiting the emission treatment unit, the controller regulates the flow of the second fuel stream into the fuel conversion unit in accordance with the received signal.   
   
   
       4 . The system of  claim 3 , further comprising:
 an NOx sensor located downstream of the emission treatment unit and in communication with the second fuel controller, the sensor measures the concentration of NOx in the treated emission stream and sends a signal to the second fuel controller representing the measured concentration.   
   
   
       5 . The system of  claim 3 , further comprising:
 a second fuel pump in communication with the second fuel controller to pump the second fuel stream to the fuel conversion unit.   
   
   
       6 . The system of  claim 1 , further comprising:
 a reductant controller that receives a signal representing a concentration of NOx in a treated exhaust stream exiting the emission treatment unit, the reductant controller regulates the flow of the reductant stream into the exhaust stream in accordance with the signal.   
   
   
       7 . The system of  claim 6 , further comprising:
 an NOx sensor located downstream of the emission treatment unit and in communication with the reductant controller, the sensor measures the concentration of NOx in the treated emission stream and sends a signal to the reductant controller representing the measured concentration.   
   
   
       8 . The system according to  claim 6 , further comprising:
 a reductant pump in communication with the reductant controller to pump at least a portion of the reductant stream into the exhaust stream.   
   
   
       9 . The system according to  claim 1 , wherein the reductants comprise hydrogen, hydrocarbons, or a combination thereof. 
   
   
       10 . The system according to  claim 9 , wherein the reductants comprise diesel fuel, partially cracked diesel fuel, gasoline, an olefin, paraffin, isoparaffin, olefinic ester, aromatic, oxygenate reductant, or a combination thereof. 
   
   
       11 . The system according to  claim 10 , wherein the oxygenate reductant comprises an alcohol, aldehyde, or ketone, or a combination thereof. 
   
   
       12 . The system according to  claim 1 , wherein the emission treatment unit is a selective catalytic reduction treatment unit. 
   
   
       13 . The system according to  claim 1 , wherein the first and second fuel streams comprise diesel fuel, biodiesel fuel, green diesel fuel or Fischer-Tropsch fuel, or any combination thereof. 
   
   
       14 . The system according to  claim 13 , wherein the first and second fuel streams comprise biodiesel fuel. 
   
   
       15 . The system according to  claim 1 , wherein the engine is a liquid fueled engine, a compression ignition engine, or a gasoline engine, or any combination thereof. 
   
   
       16 . The system according to  claim 15 , wherein the gasoline engine is a lean burn gasoline engine. 
   
   
       17 . The system according to  claim 1 , wherein the first fuel stream and second fuel stream comprise an additive component. 
   
   
       18 . The system according to  claim 17 , wherein the additive component is an alcohol, aldehyde, or ketone, or a combination thereof. 
   
   
       19 . The system according to  claim 1 , wherein the reductant stream is a gaseous reductant stream, and the method further comprises:
 a condenser configured to receive the gaseous reductant stream exiting the fuel conversion unit and condense at least a portion of the gaseous reductant stream.   
   
   
       20 . The system according to  claim 19 , wherein the condenser unit is configured to supply the condensed portion of the reductant stream to the fuel tank, and supply the remaining gaseous reductant stream to the exhaust stream, and wherein the reductants present in the gaseous reductant stream are more active than the reductants present in the condensed portion of the reductant stream. 
   
   
       21 . A method for the on-board production of reductants comprising:
 supplying a first fuel stream to an engine, wherein the engine is configured to create an exhaust stream;   supplying a second fuel stream and a stream comprising oxygen to a fuel conversion unit;   partially oxidizing at least a portion of the second fuel stream in the fuel conversion unit to form reductants;   supplying a reductant stream comprising the reductants to the exhaust stream; and   performing a selective catalytic reduction of NOx present in the exhaust stream.   
   
   
       22 . The method of  claim 21 , wherein the first and second fuel streams are supplied directly or indirectly from a fuel tank. 
   
   
       23 . The method of  claim 21 , further comprising:
 sensing a concentration of NOx in a treated exhaust stream exiting the emission treatment unit; and   regulating the flow of the second fuel stream into the fuel conversion unit in accordance with the sensed signal.   
   
   
       24 . The method of  claim 21 , further comprising:
 sensing a concentration of NOx in a treated exhaust stream exiting the emission treatment unit; and   regulating the flow of the reductant stream into the exhaust stream in accordance with the sensed signal.   
   
   
       25 . The method according to  claim 21 , wherein the reductants comprise hydrogen, hydrocarbons, or a combination thereof. 
   
   
       26 . The method according to  claim 25 , wherein the reductants comprise diesel fuel, partially cracked diesel fuel, gasoline, an olefin, paraffin, isoparaffin, olefinic ester, aromatic, oxygenate reductant, or a combination thereof. 
   
   
       27 . The method according to  claim 26 , wherein the oxygenate reductant comprises an alcohol, aldehyde, or ketone, or a combination thereof. 
   
   
       28 . The method according to  claim 21 , wherein the first and second fuel streams comprise diesel fuel, biodiesel fuel, green diesel fuel, Fischer-Tropsch fuel, and any combination thereof. 
   
   
       29 . The method according to  claim 28 , wherein the first and second fuel streams comprise biodiesel fuel. 
   
   
       30 . The method according to  claim 21 , wherein the engine is a liquid fueled engine, a compression ignition engine, a gasoline engine, and any combination thereof. 
   
   
       31 . The method according to  claim 21 , wherein the first fuel stream and second fuel stream comprise an additive component. 
   
   
       32 . The method according to  claim 31 , wherein the additive component is an alcohol, aldehyde, or ketone, or a combination thereof. 
   
   
       33 . The method according to  claim 21 , wherein the first and second fuels streams are supplied by a fuel tank, and the method further comprises:
 condensing a portion of the reductants formed by the fuel conversion unit; and   supplying the condensed reductants to the fuel tank.