Method for monitoring the performance of a catalytic converter using post catalyst methane measurements
First Claim
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1. A method for monitoring and controlling the performance of a catalytic converter comprising the steps of:
- detecting the presence of methane in an exhaust gas stream exiting the catalytic converter;
detecting the presence of a plurality of non-methane hydrocarbons in the exhaust gas stream exiting the catalytic converter;
measuring a phase shift between methane and the plurality of non-methane hydrocarbons;
determining a hydrocarbon conversion efficiency;
comparing the hydrocarbon conversion efficiency with pass/fail criteria to determine an operational status of the catalytic converter; and
outputting the operational status to an operator display.
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Abstract
A method for monitoring and controlling the performance of a catalytic converter (34) includes monitoring an exhaust gas stream from an engine (16) for the presence of methane. Upon detecting methane in the exhaust gas stream an oxygen storage level of a catalyst within the catalytic converter (34) is determined. The oxygen storage level is compared with a reference standard and the air/fuel ratio of the exhaust gas stream is continuously adjusted to maintain the oxygen storage level within predetermined control limits.
26 Citations
15 Claims
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1. A method for monitoring and controlling the performance of a catalytic converter comprising the steps of:
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detecting the presence of methane in an exhaust gas stream exiting the catalytic converter; detecting the presence of a plurality of non-methane hydrocarbons in the exhaust gas stream exiting the catalytic converter; measuring a phase shift between methane and the plurality of non-methane hydrocarbons; determining a hydrocarbon conversion efficiency; comparing the hydrocarbon conversion efficiency with pass/fail criteria to determine an operational status of the catalytic converter; and outputting the operational status to an operator display. - View Dependent Claims (2, 3)
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4. A method for monitoring and controlling the performance of a catalytic converter comprising the steps of:
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analyzing an exhaust gas stream exiting the catalytic converter for the presence of methane and non-methane hydrocarbons; adjusting an air/fuel ratio in the exhaust gas stream when methane is detected; measuring a phase shift between methane and the non-methane hydrocarbons; using the phase shift to determine a hydrocarbon conversion efficiency of the catalytic converter; comparing the hydrocarbon conversion efficiency with pass/fail criteria; and outputting a status signal to a display device. - View Dependent Claims (5, 6, 7)
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8. A method for monitoring and controlling the performance of a catalytic converter comprising the steps of:
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monitoring an exhaust gas stream exiting the catalytic converter for a methane signal; upon detecting the methane signal, determining an oxygen storage level of a catalyst within the catalytic converter; comparing the oxygen storage level with a reference standard; and continuously adjusting an air/fuel ratio in the exhaust gas stream to maintain the oxygen storage level within predetermined control limits.
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9. A method for monitoring and controlling the performance of a catalytic converter comprising the steps of:
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monitoring an exhaust gas stream exiting the catalytic converter for a methane signal; upon detecting the methane signal determining an oxygen storage level of a catalyst within the catalytic converter; comparing the oxygen storage level with a reference standard; continuously adjusting an air/fuel ratio in the exhaust gas stream to maintain the oxygen storage level within predetermined control limits; monitoring the exhaust gas stream exiting the catalytic converter for a selected species within a of plurality of non-methane hydrocarbons; measuring a phase shift between methane and the selected species; using the phase shift to determine a hydrocarbon conversion efficiency of the catalytic converter; comparing the hydrocarbon conversion efficiency with pass/fail criteria; and outputting a status signal to a display device. - View Dependent Claims (10)
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11. A method for monitoring and controlling the performance of a catalytic converter comprising the steps of:
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controlling the air/fuel ratio of a feedgas entering an engine; monitoring an exhaust gas stream exiting the catalytic converter for the presence of methane; and upon detecting methane, reducing a fuel level in the feedgas to make the feedgas more lean. - View Dependent Claims (12, 13)
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14. A method for monitoring and controlling the performance of a catalytic converter comprising the steps of:
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controlling the air/fuel ratio of a feedgas entering an engine; monitoring an exhaust gas stream exiting the catalytic converter for the presence of methane; upon detecting methane, reducing a fuel level in the feedgas to make the feedgas more lean; monitoring the exhaust gas stream for the presence of non-methane hydrocarbons; upon detecting only methane, removing a first amount of fuel from the feedgas; and upon detecting non-methane hydrocarbons, reducing a second amount of fuel from the feedgas, wherein the second amount of fuel is greater than the first amount of fuel.
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15. A method for monitoring and controlling the performance of a catalytic converter comprising the steps of:
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controlling the air/fuel ratio of a feedgas entering an engine; monitoring an exhaust gas stream exiting the catalytic converter for the presence of methane; upon detecting methane, reducing a fuel level in the feedgas to make the feedgas more lean; monitoring the exhaust gas stream for the presence of non-methane hydrocarbons; calculating a phase shift between methane and the non-methane hydrocarbons; determining a conversion efficiency of the catalytic converter; comparing the conversion efficiency with a threshold value; and activating an alarm whenever the conversion efficiency is less than the threshold value.
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Specification