An exhaust gas system (1) has a main flow path (2) with an exhaust gas aftertreatment device (4), and a bypass flow path (3) that has a fan (5) and a heating apparatus (6). The bypass flow path (3) has opposite ends connected to the main flow path (2) in regions upstream and downstream of the exhaust gas aftertreatment device (4). A shut-off (7) is arranged in the main flow path (2) upstream of the bypass flow path, and a further shut-off (8) is arranged in the main flow path downstream of the bypass flow path.

The deterioration of an exhaust gas purification catalyst is suppressed as much as possible. An exhaust gas purification system for an internal combustion engine comprising: a throttle valve; a turbocharger; an exhaust gas purification catalyst; a bypass passage; a turbo bypass valve (TBV); and a controller. The controller is configured to carry out fuel cut processing and deterioration suppression control. In the deterioration suppression control, when a temperature of the exhaust gas purification catalyst is equal to or higher than a predetermined temperature in the course of the execution of the fuel cut processing, the degree of opening of the TBV becomes smaller, and the degree of opening of the throttle valve becomes larger, than when the temperature of the exhaust gas purification catalyst is lower than the predetermined temperature in the course of the execution of the fuel cut processing.

Disclosed is a method for selective catalytic reduction operating by desorbing ammonia from at least one storage cartridge in an exhaust line at the output of a motor vehicle engine, the cartridge being arranged in at least one bypass branch of a main line of the exhaust line. The exhaust gas flow rate in the bypass branch is controlled according to an estimated or measured temperature in the bypass branch and a desired amount of ammonia to be injected by desorption estimated in the exhaust line to provide a catalytic reduction of the nitrogen oxides present in the exhaust gas, a temperature of the cartridge being estimated according to the gas flow rate at the temperature estimated or measured during a given time interval and corresponding to an amount of desorbed ammonia equal to the desired amount of ammonia.

An exhaust after-treatment system includes a first set of exhaust after-treatment components, a second set of exhaust after-treatment components, an inlet to the exhaust after-treatment system, an outlet from the exhaust after-treatment system, and a valve and conduit arrangement configurable in a plurality of modes, in a first mode, exhaust gas entering the inlet flows through the second set of exhaust after-treatment components, then through the first set of exhaust after-treatment components, and then through the outlet. In a second mode, exhaust gas entering the inlet flows through the second set of exhaust after-treatment components without flowing through the first set of exhaust after-treatment components, and then through the outlet in a third mode, exhaust gas entering the inlet flows through the first set of exhaust after-treatment components, then through the second set of exhaust after-treatment components, and then through the outlet.

Embodiments of emission reduction system including various embodiments of an emission filters for a power plant including a gas turbine are disclosed. The system includes: an emission filter; and a retraction system operably coupled to an exhaust passage of the gas turbine. The exhaust passage defines an exhaust path of exhaust from the gas turbine. The retraction system selectively moves the emission filter between a first location within the exhaust path and a second location out of the exhaust path. In a combined cycle power plant, the first location is upstream of a heat recovery steam generator (HRSG). The systems and filters described allow for temporary positioning of emission filter(s) just downstream of a gas turbine exhaust outlet, or upstream of an HRSG, where provided, for emission reduction at low loads or startup conditions, and removal of the emission filter(s) once operations move to higher loads.

Embodiments of emission reduction system including various embodiments of an emission filters for a power plant including a gas turbine are disclosed. The system includes: an emission filter; and a retraction system operably coupled to an exhaust passage of the gas turbine. The exhaust passage defines an exhaust path of exhaust from the gas turbine. The retraction system selectively moves the emission filter between a first location within the exhaust path and a second location out of the exhaust path. In a combined cycle power plant, the first location is upstream of a heat recovery steam generator (HRSG). The systems and filters described allow for temporary positioning of emission filter(s) just downstream of a gas turbine exhaust outlet, or upstream of an HRSG, where provided, for emission reduction at low loads or startup conditions, and removal of the emission filter(s) once operations move to higher loads.

The present disclosure relates to a combustion engine system and a method of operation thereof. The combustion engine system includes a pollutant conversion system and an exhaust gas turbocharger that includes a variable turbine geometry and a waste gate valve. The variable turbine geometry includes adjustable guide elements surrounding the turbine wheel in a circumferential direction and are arranged to define an overall cross-section in their respective position for the exhaust gas. In a control mode where the pollutant conversion system comprises a temperature above a threshold temperature, the guide elements are adjusted such that the overall cross-section is between a control minimum value and a control maximum value. In a heat-up mode at temperatures of the pollutant conversion system below the threshold temperature, the guide elements are moved to a heat-up position where the overall cross-section is smaller than the control minimum value.

A heater may include: a conductive ceramic cylinder tube in which cell-arrays are concentrically arranged, each cell-array including cells which are arranged in a circumstance direction of the ceramic cylinder tube; an inner electrode electrically coupled to an inner wall portion of the ceramic cylinder tube; and an outer electrode electrically coupled to an outer wall portion of the ceramic cylinder tube. Non-linear portions are radially arranged in the ceramic cylinder tube, each non-linear portion extending in a radial direction of the ceramic cylinder tube while having a plurality of bends or curves between the inner wall portion and outer wall portion of the ceramic cylinder tube. The inner and outer electrodes are provided such that current flows radially at least via said non-linear portions between the inner and outer electrodes.

An internal combustion engine system includes an engine and an aftertreatment system that is connected to the engine to receive an exhaust flow from the engine. The aftertreatment system includes a contaminant storage catalyst for storing contaminants produced by the engine during cold start and low temperature operating conditions, and a NO.sub.x reduction catalyst downstream of the storage catalyst for receiving the contaminants released from the storage catalyst when temperature conditions in the exhaust flow and/or NO.sub.x reduction catalyst are above an effective temperature threshold for NO.sub.x reduction. A contaminant amount stored on the storage catalyst can be estimated in response to one or more operating parameters to manage a storage capacity of the storage catalyst. A bypass can used to bypass the storage catalyst to preserve storage capacity for a subsequent cold start condition.

An exhaust gas treatment arrangement for an exhaust gas system of an internal combustion engine includes a first exhaust gas flow path leading from an exhaust gas inlet provided on a housing to an exhaust gas outlet provided on the housing and a second exhaust gas flow path leading from the exhaust gas inlet to the exhaust gas outlet. The second exhaust gas flow path is separate from the first exhaust gas flow path. A flow path switching unit changes the exhaust gas stream parts, which are conducted in the first exhaust gas flow path and the second exhaust gas flow path. A reactant supply device supplies reactant into the second exhaust gas flow path downstream of the exhaust gas inlet and an SCR catalyst arrangement is provided in the second exhaust gas flow path upstream of the exhaust gas outlet.