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An exhaust-gas cleaning system includes a nitrogen oxide reduction catalytic converter for reducing nitrogen oxides which are contained in the exhaust gas. A reducing agent is introduced into the exhaust-gas flow and is in the form of a vapor. A reducing-agent metering device for the metered additio

An exhaust-gas cleaning system includes a nitrogen oxide reduction catalytic converter for reducing nitrogen oxides which are contained in the exhaust gas. A reducing agent is introduced into the exhaust-gas flow and is in the form of a vapor. A reducing-agent metering device for the metered addition of the reducing agent or a reducing-agent precursor to the exhaust-gas flow includes a vaporizer, which is arranged in the exhaust system upstream of the nitrogen oxide reduction catalytic converter. As a heat source, the vaporizer has (1) a heatable deflector surface, onto which the reducing agent, which is supplied by a feed unit, is directed under pressure; or (2) a microwave generator.

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1. An exhaust-gas cleaning system, comprising:a nitrogen oxide reduction catalytic converter for reducing nitrogen oxides contained in an exhaust gas; anda reducing-agent metering device for metered addition of the reducing agent or a reducing-agent precursor to the exhaust gas,wherein said reducing

1. An exhaust-gas cleaning system, comprising:a nitrogen oxide reduction catalytic converter for reducing nitrogen oxides contained in an exhaust gas; anda reducing-agent metering device for metered addition of the reducing agent or a reducing-agent precursor to the exhaust gas,wherein said reducing-agent metering device comprises:a feed unit;a vaporizer arranged upstream of the nitrogen oxide reduction catalytic converter; anda heat source disposed in the exhaust gas, the heat source comprising a single baffle plate, the baffle plate being oriented with its planar faces parallel to a direction of flow of the exhaust gas,wherein the reducing agent is directed by the feed unit toward the single baffle plate under pressure at a substantially perpendicular angle onto one of the planar faces of the baffle plate.2. An exhaust-gas cleaning system according to claim 1, wherein a surface of the baffle plate is arranged against an inside surface of a pipe of the exhaust-gas cleaning system or is arranged in an interior of the pipe.3. An exhaust-gas cleaning system according to claim 1, wherein the exhaust gas flows through a main-flow exhaust system section, and the deflector plate is arranged in a part-flow branch line of the exhaust-gas cleaning system that branches off from the main-flow exhaust system section at a branching point and opens back into the main-flow exhaust system section downstream of the branching point.4. An exhaust-gas cleaning system according to claim 1, further comprising two catalytic converter stages connected in series, wherein each catalytic converter stage has a different reducing-agent storage capacity and wherein at least one of the catalytic converter stages forms the nitrogen oxide reduction catalytic converter.5. A motor vehicle internal combustion engine comprising the exhaust-gas cleaning system according to claim 1.