A method for ascertaining an exhaust gas composition of an exhaust gas of an internal combustion engine with regard to an ammonia fraction and a nitrogen oxides fraction in an exhaust gas system including an SCR catalytic converter. The method includes detecting, using a sensor, a first signal whose magnitude is a function of the nitrogen oxides fraction of the exhaust gas upstream from the SCR catalytic converter, detecting using a sensor a second signal whose magnitude is a function of the ammonia fraction and the nitrogen oxides fraction of the exhaust gas downstream from the SCR catalytic converter, storing the two signals over an observation period, and ascertaining the ammonia fraction and optionally the nitrogen oxides fraction of the exhaust gas downstream from the at least one SCR catalytic converter using a calculation rule that uses the two signals during the observation period as input variables.

A method for monitoring a gas sensor (14) which comprises two electrochemical measuring cells (20, 30) and which is arranged in an exhaust tract (10) of an internal combustion engine (11), wherein the sensor elements (20, 30) exhibit a substantially identical sensitivity towards a first gas component and a different sensitivity towards a second gas component and are insensitive towards further gas components. In an operating state in which an exhaust gas stream at the gas sensor (14) contains less of the second gas component than of the first gas component a concentration of the first gas component is calculated from each of the sensor signals from the sensor elements (20, 30) and a defect in a sensor element (20, 30) is deduced from the concentrations of the first gas component.

The disclosure relates to a method for optimizing the state of a catalytic converter in a vehicle with a diesel engine when parking the vehicle, the method comprising establishing that a switch-off process for switching off the diesel engine has been initiated, increasing an NH3 feed rate to a first value in order to store a surplus of NH3 in the catalytic converter, stopping the NH3 feed when the speed of the diesel engine falls below a speed threshold or a measured NH3 emission exceeds an emission threshold, and completing the switch-off process. The disclosure also relates to an engine controller and to a computer program.

The present invention relates to an apparatus for reducing greenhouse gas emission in a vessel and a vessel including the same, in which CO.sub.2 absorbed by taking only a part of the absorbent liquid used when collecting CO.sub.2 is removed, so that the device sizes of an absorbent liquid recycling unit and an absorbent liquid circulating unit is kept small and continuous operation is enabled. Or in which exhaust gas is cooled by a heat exchange method, thereby preventing the decrease in a concentration of an absorbent liquid, and CO.sub.2 absorbed by taking only a part of the absorbent liquid used when collecting CO.sub.2 is removed and an unreacted absorbent liquid is continuously circulated, thereby enabling continuous operation.

In a process for adapting an amount of reducing agent for a removal of nitrogen oxides from the gases in an exhaust line, a first alignment of the amounts of nitrogen oxides measured by upstream and downstream sensors is performed without injection of agent and with a catalyst of the system emptied of ammonia. A second alignment of the estimated reduction of nitrogen oxides with the measured reduction is performed by a difference between amounts of nitrogen oxides upstream and downstream during a substoichiometric injection of reducing agent without creating a store of ammonia in a catalyst of the system with a first correction of the amount of agent. A third alignment of an estimated efficiency of retaining nitrogen oxides with a efficiency measured by the sensors is performed, this third alignment taking place via a second correction of the amount of reducing agent injected as an adaptive correction.

A method for monitoring a concentration of a corrosive gas including at least observing at least one gas fuse, the gas fuse having at least one metal wire, which is configured for breaking due to corrosion if exposed to the corrosive gas in a way that a time-integrated concentration of the corrosive gas exceeds a critical value.

The disclosure relates to a method for optimizing the state of a catalytic converter in a vehicle with a diesel engine when parking the vehicle, the method comprising establishing that a switch-off process for switching off the diesel engine has been initiated, increasing an NH3 feed rate to a first value in order to store a surplus of NH3 in the catalytic converter, stopping the NH3 feed when the speed of the diesel engine falls below a speed threshold or a measured NH3 emission exceeds an emission threshold, and completing the switch-off process. The disclosure also relates to an engine controller and to a computer program.

An internal combustion engine has an exhaust gas aftertreatment system comprising in the given order in the flow direction of the exhaust gas: a device for metering ammonia and/or a compound that can be decomposed to form ammonia into the exhaust gas to be cleaned, as a reducing agent; one or more SCR catalysts, which form a first SCR unit; one or more SCR and/or ammonia oxidation and/or ammonia slip catalysts, which form a second SCR unit; and a NO.sub.x sensor in the exhaust gas tail pipe. An amount, to be metered into the exhaust gas, of ammonia and/or of the decomposable compound is set using the nitrogen oxide concentration in the exhaust gas tail pipe that is determined by the NO.sub.x sensor, and the occurrence or non-occurrence of an ammonia excess in the region of the NO.sub.x sensor can be determined from the sensor signal of the NO.sub.x sensor by evaluating said sensor signal.

A method for exhaust gas aftertreatment in a gasoline engine and an exhaust gas aftertreatment system are provided. In the method, two catalytic converters arranged in the exhaust gas tract of the gasoline engine are operated in different states. A first three-way catalytic converter is operated in a slightly low-oxygen range, and a second three-way catalytic converter is operated in a slightly oxygen-rich range. Secondary air is furthermore blown into the exhaust gas tract between the two three-way catalytic converters. It is thereby possible to reduce the output of emissions of the gasoline engine to a great extent. An exhaust gas aftertreatment system is likewise explained.

An exhaust gas purification device is disclosed provided with a denitration catalyst for reducing and removing nitrogen oxides in exhaust gas using ammonia as a reducing agent in a gas flow passage through which the exhaust gas discharged from a boiler flows, and which injects ammonia into the exhaust gas flowing through the gas flow passage on an upstream side of the denitration catalyst, including multiple disturbing plate support members, and a disturbing plate. The multiple disturbing plate support members are fixedly provided on a downstream side of the denitration catalyst and arranged extending linearly in a flow path cross section to cross the gas flow passage. The disturbing plate includes an exhaust gas flow facing surface exposed on an upstream side and is fixed to the disturbing plate support members so that a position thereof in the flow path cross section can be changed.