An apparatus includes a dosing module structured to suspend dosing in an exhaust aftertreatment system; a selective catalytic reduction (SCR) inlet NOx module structured to interpret SCR inlet NOx data and an SCR inlet temperature; a SCR outlet NOx module structured to interpret SCR outlet NOx data; and a system diagnostic module structured to determine an efficiency of a SCR system based on the SCR inlet and outlet NOx data over a range of SCR temperatures, wherein the system diagnostic module is further structured to determine a state of at least one of a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and the SCR system based on the SCR efficiency at an elevated SCR temperature range and the SCR efficiency at a relatively lower SCR temperature range relative to a high SCR efficiency threshold and a low SCR efficiency threshold.

A method for controlling an exhaust gas aftertreatment system, wherein the system includes a first selective catalytic reduction (SCR) device, a catalytic particulate filter arrangement arranged downstream of the first SCR device, and a second selective catalytic reduction (SCR) device arranged downstream of the catalytic particulate filter arrangement. The method includes estimating future exhaust conditions based upon predicted vehicle operating conditions (s403); —estimating a future NOx conversion demand based on the estimated future exhaust conditions (s405); —dosing a reducing agent from a first reducing agent dosing device at a rate based at least on the estimated future NOx conversion demand (s406).

A reaction device of a marine SCR system comprises a conveying unit (110), a reaction chamber (120), at least one catalyst module (130), and an air homogenization chamber (140), wherein, the conveying unit (110) includes an input pipeline (111) and an output pipeline (112) sleeved outside the input pipeline (111). One end of the reaction chamber (120) is connected to the conveying unit (110). The reaction chamber (120) comprises an inner cylinder (121) and an outer cylinder (122) sleeved outside the inner cylinder (121), the inner cylinder (121) is in communication with the input pipeline (111), and the outer cylinder (122) is in communication with the output pipeline (112). The catalyst module (130) is provided between the inner cylinder (121) and the outer cylinder (122). The air homogenization chamber (140) is connected to the other end of the reaction chamber (120) and is in communication with both the inner cylinder (121) and the outer cylinder (122). With the reaction device of the marine SCR system whereby the outer cylinder is sleeved outside the inner cylinder, flue gas from the inner cylinder is turned by the air homogenization chamber and then flows back into the outer cylinder. This can not only substantially reduce the size of the reaction device to improve the integration of the SCR system, but also allow the flue gas to turn in the air homogenization chamber and then flow back, so that the flue gas and a reducing agent can be fully mixed in the air homogenization chamber to improve the catalytic reaction efficiency.

A method for controlling emissions from a power plant having an ammonia injection grid that includes a plurality of ammonia injection points includes the steps of injecting ammonia into a flow of exhaust gas at an injection location, the injection of ammonia defining a spatial distribution of ammonia across an exhaust gas flowpath, measuring at least one parameter of the exhaust gas downstream from the injection location, comparing a measured value for the at least one parameter of the exhaust gas to a threshold value for the at least one parameter and, if the measured value for the at least one parameter exceeds the threshold value for the at least one parameter, automatically modifying the spatial distribution of ammonia injection across the exhaust gas flowpath.

An exhaust treatment system for a work vehicle includes a selective catalytic reduction (SCR) system having an SCR outlet for expelling treated exhaust flow therefrom, a flow conduit in fluid communication with the outlet, an exhaust sensor positioned within the flow conduit downstream of the outlet, and a flow mixer positioned upstream of the exhaust sensor. The flow mixer has an end wall defining sector openings circumferentially extending between first and second sector sides and radially between radially inner and outer sector ends. Moreover, the flow mixer has swirler vanes, where each of the swirler vanes extends circumferentially from the first sector side of a respective one of the sector openings and radially between radially inner and outer vane ends. Particularly, the radially outer vane end of each of the swirler vanes is spaced apart from the radially outer sector end of the respective one of the sector openings.

A selective catalytic reduction system control system (10) and method of its use include an ammonia (“NH.sub.3”) slip sensor (13) located within an interior space (27) of an exhaust stack (15) of a selective catalytic reactor (31), toward an inlet end (25) of the stack (15); a housing (17) located within the interior space of the exhaust stack; the housing including face panels 19; a nitrogen oxides (“NOx”) sensor (11) contained within an interior space (29) defined by the face panels of the housing, at least two of the face panels (19.sub.I, 19.sub.O) containing an oxidation catalyst; and a dosing controller (59) in communication with the NH.sub.3 and NOx sensors, the dosing controller including a microprocessor with dosing logic embedded thereon. The housing with oxidation catalyst acts as a linear box, isolating the NOx sensor from NH.sub.3 slip, linearizing the NOx sensor signal.

A selective catalytic reduction (SCR) catalyst is disposed in an exhaust gas system of an internal combustion engine. A reductant injector is coupled to the exhaust gas stream at a position upstream of the SCR catalyst, and first and second NO.sub.x sensors provide NOx measurements upstream of and downstream of the SCR catalyst, respectively. A system and method is disclosed for operating the system to determine a NOx amount and/or a NH3 slip amount downstream of the SCR catalyst by decoupling NOx-NH3 measurements from the output of the second NOx sensor to provide control of the reductant injection amount.

An internal combustion engine (ICE) and method of control are provided to determine a value of a catalyst temperature and a value of a quantity of a reducing agent stored in the catalyst. The quantity of gas recirculated by an exhaust gas recirculation (EGR) system of the ICE is calculated on the basis of the value of the catalyst temperature and of the value of the quantity of the reducing agent stored in the catalyst. This solution makes it possible to adjust the quantity of gas recirculated by the EGR system on the basis of parameters linked to an efficiency of a selective catalytic reduction (SCR) system associated with the ICE, in order to reduce the global quantity of pollutants produced by the ICE and released in the environment.

A controller calculates a period travel distance that is a travel distance of the vehicle from when the available travel distance is calculated to when the available travel distance is calculated next. The controller, when the remaining amount of urea aqueous solution inside a tank exceeds a predetermined amount, executes a first calculation process in which the available travel distance is calculated with reference to the remaining amount of the urea aqueous solution. The controller, after the remaining amount of the urea aqueous solution becomes smaller than or equal to a predetermined amount, executes a second calculation process in which the available travel distance is calculated by subtracting the period travel distance from the previously calculated available travel distance.

A method for an exhaust system is provided, comprising adjusting reductant injection responsive to a reductant concentration, the reductant concentration based on concentration sensor readings and vehicle motion. If the reductant freezes, the reductant may stratify, leading to inaccurate concentration sensor readings. Vehicle motion may mix the reductant, thereby ensuring an accurate concentration measurement which may then be used to adjust reductant injection.