After-treatment system and method for reducing emissions in diesel engine exhaust
First Claim
1. A method of heating the exhaust gas of an internal combustion engine comprising the steps of:
- determining a first temperature of the exhaust gas at a point downstream of a first oxidation device;
maintaining the air-to-fuel ratio entering the engine;
selectively increasing the level of oxygen and the level of a reactant in the exhaust gas by introduction of oxygen and the reactant into the exhaust gas before it enters the first oxidation device in response to the first temperature of the exhaust gas;
catalytically oxidizing the exhaust gas, wherein the catalytic oxidation of the reactant introduced into the exhaust gas raises the temperature of the exhaust gas; and
introducing the exhaust gas after the first oxidation device into a NOx abatement device.
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Abstract
An after-treatment system arrangement and method of operating the after-treatment system arrangement is provided for heating the exhaust gas of an internal combustion engine. The after-treatment system arrangement includes an oxidation device for catalytically oxidizing the exhaust gas and a port in the exhaust-gas stream for selectively introducing a controlled amount of oxygen into the exhaust gas in response to a condition of the exhaust gas. The introduction of oxygen can be selectively controlled in response to the temperature of the exhaust gas downstream of the oxidation device. Simultaneously or alternatively, the introduction of oxygen can be selectively controlled in response to the chemical composition of the exhaust gas. The air-to-fuel ratio of the exhaust gas may also be controlled to further facilitate heating of the exhaust gas. The after-treatment system arrangement can also be controlled to remove pollutant emissions from the exhaust gas.
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Citations
29 Claims
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1. A method of heating the exhaust gas of an internal combustion engine comprising the steps of:
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determining a first temperature of the exhaust gas at a point downstream of a first oxidation device;
maintaining the air-to-fuel ratio entering the engine;
selectively increasing the level of oxygen and the level of a reactant in the exhaust gas by introduction of oxygen and the reactant into the exhaust gas before it enters the first oxidation device in response to the first temperature of the exhaust gas;
catalytically oxidizing the exhaust gas, wherein the catalytic oxidation of the reactant introduced into the exhaust gas raises the temperature of the exhaust gas; and
introducing the exhaust gas after the first oxidation device into a NOx abatement device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An after-treatment system arrangement for heating the exhaust gas of an internal combustion engine comprising:
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an oxidation device for catalytically oxidizing the exhaust gas;
a NOx abatement device connected downstream of the oxidation device;
an oxygen source;
a source of reactants; and
a first port upstream of the oxidation device for selectively introducing a controlled amount of oxygen and a second port upstream of the oxidation device for selectively introducing a controlled amount of reactants into the exhaust gas in response to the temperature of the exhaust gas as determined at a point downstream of the oxidation device. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method of reducing emissions in the exhaust-gas of a diesel engine, comprising:
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(a) when the air-to-fuel ratio of the exhaust gas is lean in fuel, catalytically oxidizing in a first oxidation device the exhaust gas from the engine, selectively increasing the level of oxygen and the level of reactants in the exhaust gas by introduction of oxygen and reactants into the exhaust gas before it enters the first oxidation device in response to a first temperature of the exhaust gas measured downstream of the first oxidation device, wherein the catalytic oxidation of the reactants introduced into the exhaust gas raises the temperature of the exhaust gas exiting the first oxidation device;
removing nitrogen oxides from the exhaust gas in a NOx abatement device; and
collecting particulate matter contained in the exhaust gas in a particulate filter; and
(b) periodically regenerating one or both of the NOx abatement device and the particulate matter filter by intentionally shifting the air-to-fuel ratio of the exhaust to a fuel rich air-to-fuel ratio and selectively introducing a controlled amount of oxygen into the exhaust gas prior to a second oxidation device downstream of the NOx abatement device to facilitate heating of the exhaust gas to a temperature that promotes combustion of the collected particulate matter. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification