Sulfur detection routine

Abstract

A power system comprising an engine that produces exhaust, an aftertreatment system that treats the exhaust and includes a particulate filter that traps soot from the engine, and a controller configured to perform a sulfur detection routine that conducts a pre-regeneration calibration to achieve a temperature in the aftertreatment system of between 200 and 400 degrees Celsius and following the pre-regeneration calibration conducts a sulfur removal calibration to achieve a temperature in the aftertreatment system of between 300 and 500 degrees Celsius.

1 . A power system comprising:
 an engine that produces exhaust;   an aftertreatment system that treats the exhaust and includes a particulate filter that traps soot from the engine; and   a controller configured to perform a sulfur detection routine that:
 conducts a pre-regeneration calibration to achieve a temperature in the aftertreatment system of between 200 and 400 degrees Celsius; and 
 following the pre-regeneration calibration conducts a sulfur removal calibration to achieve a temperature in the aftertreatment system of between 300 and 500 degrees Celsius. 
   
     
     
         2 . The power system of  claim 1  wherein the aftertreatment system further includes an oxidation catalyst that converts NO from the engine into NO2 upstream of the filter. 
     
     
         3 . The power system of  claim 2  wherein following the sulfur removal calibration the sulfur detection routine conducts a post-regeneration calibration to achieve a temperature in the aftertreatment system of between 200 and 400 degrees Celsius. 
     
     
         4 . The power system of  claim 3  further including a sensor that provides an indication of the amount of soot in the particulate filter. 
     
     
         5 . The power system of  claim 4  wherein readings from the sensor are used to indicate that at least one of the oxidation catalyst and the particulate filter have been deactivated by sulfur. 
     
     
         6 . The power system of  claim 5  wherein the pre-regeneration calibration and post-regeneration calibration achieves a NOx/soot ratio in the exhaust of greater than 35/1. 
     
     
         7 . The power system of  claim 6  wherein the pre-regeneration calibration, sulfur removal calibration, and post-regeneration calibration include at least one of the following strategies:
 increasing a engine fuel injection pressure; 
 partially closing a backpressure valve disposed in an exhaust conduit; 
 closing an exhaust gas recirculation valve disposed in an exhaust gas recirculation system that recirculates the exhaust from the engine back to an intake of the engine; 
 changing a fuel injection timing of when a main injection of fuel is injected into the engine relative to the position of a piston in the engine; and 
 injecting a shot of fuel either before or after the main injection wherein the shot of fuel is smaller than the main injection. 
 
     
     
         8 . The power system of  claim 5  wherein a rate of soot removal during the pre-regeneration calibration is compared against a rate of soot removal during the post-regeneration calibration to indicate that at least one of the oxidation catalyst and the particulate filter have been deactivated by sulfur. 
     
     
         9 . The power system of  claim 8  wherein the pre-regeneration calibration is conducted immediately before the a sulfur removal calibration and the post-regeneration calibration is conducted immediately after the a sulfur removal calibration. 
     
     
         10 . The power system of  claim 8  wherein the pre-regeneration calibration, the sulfur removal calibration, and the post-regeneration calibration are conducted for a predetermined amount of time. 
     
     
         11 . The power system of  claim 9  wherein the sulfur detection routine is triggered by an operator. 
     
     
         12 . The power system of  claim 11  wherein the sulfur detection routine is enabled when the amount of soot in the particulate filter is sufficient to avoid removal of all the soot during the sulfur detection routine. 
     
     
         13 . A power system comprising:
 an engine that produces exhaust;   a fuel system that injects a fuel into the engine;   an aftertreatment system that treats the exhaust and includes a particulate filter that traps soot from the engine; and   a controller configured to perform a sulfur detection routine that:
 conducts a sulfur removal calibration to achieve a temperature in the aftertreatment system of between 300 and 500 degrees Celsius; and 
 following the sulfur removal calibration conducts a post-regeneration calibration to achieve a temperature in the aftertreatment system between 200 and 400 degrees Celsius. 
   
     
     
         14 . The power system of  claim 13  wherein the aftertreatment system further includes an oxidation catalyst that converts NO from the engine into NO2 upstream of the filter and a sensor that provides an indication of the amount of soot in the particulate filter. 
     
     
         15 . The power system of  claim 14  wherein readings from the sensor are used to indicate that at least one of the oxidation catalyst and filter have been deactivated by sulfur. 
     
     
         16 . A method of detecting sulfur in an aftertreatment system treating an exhaust from an engine, the method comprising comparing a rate of regeneration of a particulate filter after removing the sulfur against a rate of regeneration of a particulate filter before removing the sulfur. 
     
     
         17 . The method of  claim 16  wherein removing the sulfur includes raising a temperature of the exhaust to achieve a temperature in the aftertreatment system of between 300 and 500 degrees Celsius. 
     
     
         18 . The method of  claim 17  wherein the regeneration of the particulate filter includes raising a NOx/soot ratio in the exhaust to greater than 35/1 and a temperature of the exhaust to achieve a temperature in the aftertreatment system of between 200 and 400 degrees Celsius. 
     
     
         19 . The method of  claim 18  wherein the regeneration of the particulate filter further includes at least one of the following strategies:
 increasing a engine fuel injection pressure; 
 partially closing a backpressure valve disposed in an exhaust conduit; 
 closing an exhaust gas recirculation valve disposed in an exhaust gas recirculation system that recirculates the exhaust from the engine back to an intake of the engine; 
 changing a fuel injection timing of when a main injection of the fuel is injected into the engine relative to the position of a piston in the engine; and 
 injecting a shot of fuel either before or after the main injection wherein the shot of fuel is smaller than the main injection. 
 
     
     
         20 . The method of  claim 16  enabled when an amount of soot in the particulate filter is sufficient to avoid removal of all the soot during removal of the sulfur.