Mobile diesel selective catalytic reduction systems and methods
View Patent ↗The present invention provides for the retrofitting diesel truck engines with a system to reduce NOx emissions. The SCR system of the present invention, including a controller, a reagent tank, and an injection system, is installed on a vehicle. A NOx detector is temporarily installed as part of the system. The vehicle is then operated to collect engine parameters including fuel injection timing, RPM, load, exhaust heat, exhaust flow rate, and the like, together with measurements of the NOx emissions under various operating conditions. Based on the recorded data at various operating conditions, a reagent injection strategy is developed and installed at the reagent injection controller. During vehicle operation, the injector injects reagent into the exhaust system based on control signals from the reagent injection controller in accordance with the injection strategy in order to reduce NOx emissions at the various operating conditions.
1. A method for reducing NOx emissions in diesel engine exhaust installed in a vehicle, comprising:
determining at least one engine operating parameter for each of a plurality of engine operating conditions generated during normal operation of said vehicle;
temporarily installing a NOx detector for detecting respective NOx emissions at each of said engine operating conditions;
developing an injection strategy based on said at least one engine operating parameter at said respective operating condition of said vehicle and said respective detected NOx emissions;
removing said NOx detector responsive to said development of said injection strategy;
controlling the injection of a reagent into the exhaust at a variable flow rate in order to reduce NOx emissions at said various operating conditions in accordance with said injection strategy;
wherein:
said variable flow rate of said reagent is controlled by a reagent injection controller in accordance with said injection strategy based on input of one or more of said engine operating parameters.
2. A method in accordance with claim 1 , wherein said at least one engine operating parameter comprises at least one of fuel injection timing, exhaust temperature, RPM, load, engine speed, exhaust mass flow, cam position, crank angle position, or fuel injection signal.
3. A method in accordance with claim 1 , wherein said reagent comprises one of an aqueous urea reagent, aqueous ammonia, anhydrous ammonia, or a hydrocarbon based reagent.
4. A method in accordance with claim 1 , wherein said injection strategy is developed automatically by one or more algorithms in the reagent injection controller.
5. A method in accordance with claim 1 , further comprising:
specifying particular drive cycles for said normal operation of said vehicle to generate said plurality of engine operating conditions.
6. A method in accordance with claim 1 , further comprising:
identifying operating voids in said plurality of engine operating conditions;
specifying particular drive cycles to obtain engine operating conditions corresponding to said voids.
7. A method in accordance with claim 1 , wherein:
said NOx is temporarily detected by the temporary NOx detector.
8. A method in accordance with claim 1 , wherein temporary NOx detector comprises a NOx meter temporarily located external to the exhaust system.
9. A method in accordance with claim 1 , wherein said temporary NOx detector comprises a NOx sensor temporarily installed within the exhaust system.
10. A method in accordance with claim 1 , wherein said injection strategy is developed by post-processing the detected NOx emissions and the at least one engine operating parameter.
11. A method in accordance with claim 10 , wherein said injection strategy is downloaded to the reagent injection controller.
12. A method in accordance with claim 1 , wherein said injection strategy is provided in the form of multiple injection maps.
13. A method in accordance with claim 12 , wherein said multiple injection maps are provided in lookup tables at said reagent injection controller.
14. A method in accordance with claim 1 , further comprising:
providing at least one SCR catalyst bed in an exhaust system having selective catalytic reduction properties to enable conversion of said Nox emissions into water, nitrogen and carbon dioxide after interaction with said reagent.
15. A method in accordance with claim 14 , wherein said SCR catalyst bed comprises at least one of titanium oxide, vanadium, molybdenum, tungsten oxide, or zeolite.