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BR-102022018833-B1 - METHOD FOR MONITORING AN OXIDATION CATALYST, SYSTEM FOR MONITORING AN OXIDATION CATALYST AND SYSTEM FOR MONITORING AN OXIDATION CATALYST FOR A LEAN-BURNING INTERNAL COMBUSTION ENGINE

BR102022018833B1BR 102022018833 B1BR102022018833 B1BR 102022018833B1BR-102022018833-B1

Abstract

EXHAUST AFTERTREATMENT SUBSYSTEM. An exhaust aftertreatment system and associated system for purifying an exhaust gas feed stream from a lean-combustion engine includes an oxidation catalyst that is arranged upstream of a selective catalytic reduction (SCR) catalyst. A first NOx sensor is arranged upstream and a second NOx sensor is arranged downstream of the oxidation catalyst. A controller is arranged to monitor the oxidation catalyst based on the inputs from the first and second NOx sensors. A first NOx parameter is determined through the first NOx sensor, and a second NOx parameter is determined through the second NOx sensor. A NO2 parameter is determined based on the first NOx parameter, the second NOx parameter, a first ratio for the first and second NOx sensors, and a second ratio for the first and second NOx sensors. The NO2 production of the oxidation catalyst is evaluated based on the NO2 parameter.

Inventors

  • TREVOR JOSEPH OTT
  • CYNTHIA CHAFFIN WEBB
  • CHARLES WAYNE REINHARDT SWART

Assignees

  • PACCAR INC

Dates

Publication Date
20260317
Application Date
20220920
Priority Date
20210922

Claims (17)

  1. 1. Method for monitoring an oxidation catalyst (32) that is disposed in an exhaust gas feed stream (15) of a compression ignition internal combustion engine (10), the method comprising: disposing of a first NOx sensor (14) to monitor the exhaust gas feed stream (15) upstream of the oxidation catalyst (32) and disposing of a second NOx sensor (48) to monitor the exhaust gas feed stream (15) downstream of the oxidation catalyst (32); determining a first relationship for the first and second NOx sensors corresponding to nitrogen oxide (NOx); determining a second relationship for the first and second NOx sensors corresponding to nitrogen dioxide (NO2); determining, through the first NOx sensor (14), a first NOx parameter; determining, through the second NOx sensor (48), a second NOx parameter; determining a NO2 parameter based on the first NOx parameter, the second NOx parameter, the first relationship for the first and second NOx sensors and in the second relationship for the first and second NOx sensors; evaluate the NO2 production of the oxidation catalyst (32) based on the NO2 parameter; the method CHARACTERIZED by the fact that it also includes: communicating, through a controller, the evaluation of NO2 production by the oxidation catalyst (32), wherein the determination of the NO2 parameter based on the first NOx parameter, the second NOx parameter, the first relationship for the first and second NOx sensors, and the second relationship for the first and second NOx sensors, includes the determination of NO2 production by the oxidation catalyst (32) based on the following relationship: NO2DOC = (1+(SlopeFTIR/SlopeNOxNO2))*(NOxsi - NOxs2) wherein: NO2DOC represents the NO2 production by the oxidation catalyst (32); slopeFTIR represents the first relationship for the first and second NOx sensors; slopeNOxNO2 represents the second relationship for the first and second NOx sensors; NOxsi represents the first NOx parameter; and NOxs2 represents the second NOx parameter.
  2. 2. Method, according to claim i, CHARACTERIZED in that the evaluation of NO2 production of the oxidation catalyst (32) based on the NO2 parameter comprises detecting a failure in the oxidation catalyst (32) when the NO2 parameter is greater than a first limit.
  3. 3. Method, according to claim i, CHARACTERIZED in that the evaluation of NO2 production of the oxidation catalyst (32) based on the NO2 parameter comprises detecting a failure in the oxidation catalyst (32) when the NO2 parameter is below a second limit.
  4. 4. Method according to claim i, CHARACTERIZED in that it further comprises a selective catalytic reduction (sCR) catalyst (20) and a reductant distribution system (25) disposed in the exhaust gas feed stream (i5) downstream of the first NOx sensor (i4) and upstream of the oxidation catalyst (32); and wherein the method further comprises employing the NO2 parameter as a response parameter to control the reductant distribution system (25) to inject the reductant into the exhaust gas feed stream (i5) to achieve a target reductant/NOx ratio.
  5. 5. Method according to claim i, CHARACTERIZED in that the first relationship for the first and second NOx sensors is based on a magnitude of NOx molecules in the exhaust gas feed stream (15).
  6. 6. Method according to claim 1, CHARACTERIZED in that the second relationship for the first and second NOx sensors is based on a magnitude of NO2 molecules in the exhaust gas feed stream (15).
  7. 7. Method according to claim 1, CHARACTERIZED in that it further comprises monitoring, by means of the second of the NOx sensors, the exhaust gas feed flow (15) downstream of the oxidation catalyst (32) and upstream of a subsequent exhaust after-treatment device.
  8. 8. System for monitoring an oxidation catalyst (32) arranged in an exhaust gas feed stream (15) of a compression ignition internal combustion engine (10), comprising: a first NOx sensor (14) arranged to monitor the exhaust gas feed stream (15) upstream of the oxidation catalyst (32); a second NOx sensor (48) arranged to monitor the exhaust gas feed stream (15) downstream of the oxidation catalyst (32); a controller, in communication with the first and second NOx sensors; the controller including a set of instructions, the set of instructions including: a first relationship to the first and second NOx sensors corresponding to nitrogen oxide (NOx); a second relationship to the first and second NOx sensors corresponding to nitrogen dioxide (NO2); wherein the set of instructions is executable to: determine, through the first NOx sensor (14), a first NOx parameter; determine, through the second NOx sensor (48), a second parameter of NOx; determine a NO2 parameter based on the first NOx parameter, the second NOx parameter, the first relationship for the first and second NOx sensors and the second relationship for the first and second NOx sensors; evaluate the NO2 production of the oxidation catalyst (32) based on the NO2 parameter; CHARACTERIZED by communicating the evaluation of NO2 production from the oxidation catalyst (32) to a second controller, wherein the instruction set being executable to determine the NO2 parameter based on the first NOx parameter, the second NOx parameter, the first relationship for the first and second NOx sensors and the second relationship for the first and second NOx sensors comprises the instruction set being executable to determine the NO2 production by the oxidation catalyst (32) based on the following relationship: NO2DOC = (1+(SlopeFTIR/SlopeNOxNO2))*(NOxsi - NOxs2) wherein: NO2DOC represents the NO2 production by the oxidation catalyst (32); slopeFTIR represents the first relationship for the first and second NOx sensors; slopeNOxNO2 represents the second relationship for the first and second NOx sensors; NOxsi represents the first NOx parameter; and NOxs2 represents the second NOx parameter.
  9. 9. System according to claim 8, CHARACTERIZED in that the set of instructions being executable to evaluate the NO2 production of the oxidation catalyst (32) based on the NO2 parameter comprises the set of instructions being executable to detect a fault in the oxidation catalyst (32) when the NO2 parameter is greater than a first limit.
  10. 10. System according to claim 8, CHARACTERIZED in that the set of instructions being executable to evaluate the NO2 production of the oxidation catalyst (32) based on the NO2 parameter comprises the set of instructions being executable to detect a failure in the oxidation catalyst (32) when the NO2 parameter is below a second limit.
  11. 11. System according to claim 8, CHARACTERIZED in that the first relationship for the first and second NOx sensors is based on a magnitude of NOx molecules in the exhaust gas feed stream (15).
  12. 12. System according to claim 8, CHARACTERIZED in that the second relationship for the first and second NOx sensors is based on a magnitude of NO2 molecules in the exhaust gas feed stream (15).
  13. 13. System, according to claim 8, CHARACTERIZED in that it further comprises the executable instruction set to monitor, through the second of the NOx sensors, the exhaust gas feed flow (15) downstream of the oxidation catalyst (32) and upstream of a subsequent exhaust after-treatment device.
  14. 14. System according to claim 8, CHARACTERIZED in that it further comprises a selective catalytic reduction (SCR) catalyst (20) and a reductant distribution system (25) disposed in the exhaust gas feed stream (15) downstream of the first NOx sensor (14) and upstream of the oxidation catalyst (32); wherein the instruction set is executable to employ the NO2 parameter as a response parameter to control the reductant distribution system (25) to inject the reductant into the exhaust gas feed stream (15) to achieve a target reductant/NOx ratio.
  15. 15. System according to claim 14, CHARACTERIZED in that the instruction set is executable to disable the reducer distribution system (25) before the NO2 parameter is determined.
  16. 16. System according to claim 14, CHARACTERIZED in that it further comprises a controllable heating element, disposed in the exhaust gas feed stream (15) upstream of the SCR catalyst (20).
  17. 17. System for monitoring an oxidation catalyst (32) for a lean-burning internal combustion engine comprising: a first NOx sensor (14) arranged to monitor an exhaust gas feed stream (15) upstream of the oxidation catalyst (32); a second NOx sensor (48) arranged to monitor the exhaust gas feed stream (15) downstream of the oxidation catalyst (32); a controller, in communication with the first and second NOx sensors; the controller including a set of instructions, the instruction set including: a first relationship for the first and second NOx sensors corresponding to nitrogen oxide (NOx); and a second relationship for the first and second NOx sensors corresponding to nitrogen dioxide (NO2); wherein the instruction set is executable to: determine, through the first NOx sensor (14), a first NOx parameter; determine, through the second NOx sensor (48), a second NOx parameter; determine a NO2 parameter based on the first NOx parameter, the second NOx parameter, the first relationship for the first and second NOx sensors and the second relationship for the first and second NOx sensors; determine the NO2 production by the oxidation catalyst (32) based on the NO2 parameter; CHARACTERIZED by detecting a fault in the oxidation catalyst (32) based on NO2 production, wherein the executable instruction set to determine the NO2 parameter based on the first NOx parameter, the second NOx parameter, the first relationship for the first and second NOx sensors and the second relationship for the first and second NOx sensors comprises the executable instruction set to determine the NO2 production by the oxidation catalyst (32) based on the following relationship: NO2DOC = (1+(SlopeFTIR/SlopeNOxNO2))*(NOxsi - NOxs2) wherein: NO2DOC represents the NO2 production by the oxidation catalyst (32); slopeFTIR represents the first relationship for the first and second NOx sensors; slopeNOxNO2 represents the second relationship for the first and second NOx sensors; NOxsi represents the first NOx parameter; and NOxs2 represents the second NOx parameter.

Description

INTRODUCTION [001] Exhaust aftertreatment systems seamlessly couple to internal combustion engines to purify exhaust gases that are generated as combustion byproducts. Combustion byproducts can include unburned hydrocarbons, carbon monoxide, nitrite oxides (NOx), and particulate matter. In general, exhaust aftertreatment systems may include oxidation catalysts, reduction catalysts, selective catalytic reduction catalysts, particulate filters, and other devices. When employed in heavy-duty diesel engines or other lean-burn configurations, an exhaust aftertreatment system may include a diesel oxidation catalyst (DOC) to oxidize nitric oxide (NO), a diesel particulate filter (DPF) for particulate matter (PM) control, one or more selective catalytic reduction (SCR) catalysts for NOx reduction, and/or an ammonia oxidation catalyst to eliminate or minimize ammonia exhaust. The operation of the internal combustion engine and exhaust aftertreatment system can be monitored by one or more sensing devices arranged in the exhaust gas feed stream. Operation can also be determined using simulation models that run dynamically during operation. [002] SCR catalysts can employ reductants to reduce NOx molecules to elemental nitrogen. One reductant is urea, which can be transformed into ammonia (NH3) in an exhaust system. The reductant can be injected into the exhaust gas feedstream upstream of one or more selective catalytic reduction catalysts and can be stored on a surface or otherwise captured for use in reducing NOx molecules to elemental nitrogen and water. The performance of known SCR catalysts is temperature dependent, with increased performance being related to increased exhaust gas temperatures. [003] There is a need to provide a hardware architecture and method implementation for monitoring the performance of exhaust aftertreatment system elements, including the DOC, to improve NOx emissions from heavy-duty diesel. SUMMARY [004] An exhaust after-treatment system and associated system for purifying an exhaust gas feed stream from a lean-burning internal combustion engine or other compression-ignition engine is described. The system and method for purifying the exhaust gas feed stream includes an oxidation catalyst that is arranged upstream of a selective catalytic reduction (SCR) catalyst. A first NOx sensor is arranged to monitor the exhaust gas feed stream upstream of the oxidation catalyst, and a second NOx sensor is arranged to monitor the exhaust gas feed stream downstream of the oxidation catalyst and upstream of the SCR catalyst. A reductant distribution system is arranged to inject a reductant into the exhaust gas feed stream upstream of the SCR catalyst. A controller is operationally connected to the reductant distribution system and in communication with the first and second NOx sensors. The controller includes a set of executable instructions to monitor the oxidation catalyst based on inputs from the first and second NOx sensors. This includes determining a first ratio for the first and second NOx sensors corresponding to nitrogen oxide (NOx), and determining a second ratio for the first and second NOx sensors corresponding to nitrogen dioxide (NO2). A first NOx parameter is determined through the first NOx sensor, and a second NOx parameter is determined through the second NOx sensor. An NO2 parameter is determined based on the first NOx parameter, the second NOx parameter, the first ratio for the first and second NOx sensors, and the second ratio for the first and second NOx sensors. The NO2 production of the oxidation catalyst is evaluated based on the NO2 parameter. [005] One aspect of the disclosure includes the instruction set being executable to detect a fault in the oxidation catalyst when the NO2 parameter is greater than a first limit. [006] Another aspect of the disclosure includes the instruction set being executable to detect a fault in the oxidation catalyst when the NO2 parameter is below a second limit. [007] Another aspect of the disclosure includes the set of instructions being executable to determine the NO2 production by the oxidation catalyst based on the following relationship: NO2DOC = (1+(SlopeFTIR/SlopeNOxNO2))*(NOxsi - NOxs2), where: NO2DOC represents the NO2 production by the oxidation catalyst; slopeFTIR represents the first relationship for the first and second NOx sensors; slopeNOxNO2 represents the second relationship for the first and second NOx sensors; NOxsi represents the first NO parameter; and NOxs2 represents the second NOx parameter. [008] Another aspect of the disclosure includes the first relationship for the first and second NOx sensors being based on a magnitude of NOx molecules and a signal output. [009] Another aspect of the disclosure includes the second relationship for the first and second NOx sensors being based on a magnitude of NO2 molecules in the exhaust gas feed stream. [010] Another aspect of the disclosure includes the instruction set being executabl