A boiler or other fired vessel includes a housing with a burner at one end, a furnace downstream of the burner, a convection section downstream of the furnace and a flue gas outlet downstream of the convection section. A first means for loading a reducing agent comprising at least two injectors is located downstream of the furnace. A second means for loading a reducing agent is located downstream of the first means for loading a reducing agent. A selective catalytic reduction catalyst is located either downstream of the second means for loading a reducing agent or adjacent the second means for loading a reducing agent such that the catalyst is provided to the boiler or other fired vessel approximately simultaneously with the reducing agent from the second means for loading the reducing agent.

A controller including a self-tuning circuit for controlling a pressure system to output an input pressure corresponding to an input pressure value using an adaptive fuzzy control system and updating dosing command values of a dosing command table for controlling a dosing unit of an aftertreatment system. The self-tuning circuit is configured to determine an input pressure value and generate a pressure control signal using the adaptive fuzzy control system based on the input pressure value, a detected input pressure, and an error amount. The self-tuning circuit is further configured to regulate the input pressure of reductant to the dosing unit from a reductant tank using a pressure control signal for a pressure control device. The self-tuning circuit is further configured to update a dosing command value of a dosing command table of the controller in conjunction with regulating the input pressure of reductant.

When an integrated value of a determination value correlated with a command value for an amount of supply of a reducing agent at the time of the command value being larger than a command supply amount threshold value reaches an integration threshold value, a determination is made that a diagnosis condition is satisfied, and an abnormality in the supply of the reducing agent is diagnosed based on an integrated value of the command value for the amount of supply of the reducing agent and an integrated value of an estimated value of the amount of supply of the reducing agent, whereas in cases where a period of time in which the diagnosis condition is not satisfied is longer than a time period threshold value, an interval of supply of the reducing agent is extended.

An exhaust gas control apparatus for an internal combustion engine includes an addition valve, a tank, a urea water passage, a pump, a nitrogen oxides catalyst, and an electronic control unit. The electronic control unit is configured to: control the pump, as a first control, such that a specified amount of the urea water stored in the addition valve and the urea water passage is returned to the tank after the internal combustion engine is stopped; control the pump, as a second control, such that the specified amount or more of the urea water in the tank is discharged from the tank to the urea water passage after the first control is executed; and control the pump, as a third control, such that all the urea water stored in the addition valve and the urea water passage is returned to the tank after the second control is executed.

An object is to prevent abrasion inside an addition valve and clogging of the addition valve due to an increase in the particle diameter of precipitates. A first control is performed by which a pump is caused to operate in such a way as to return urea solution contained in the addition valve and a urea solution channel to a tank by a predetermined quantity. After the lapse of a certain time after the end of the first control, a second control is performed by which the pump is caused to operate in such a way as to return the urea solution remaining in the addition valve and the urea solution channel thoroughly to the tank.

A diesel exhaust fluid delivery system and a dual-variable control strategy for adjusting the delivery pressure and the mass flow rate of the fluid passing through the system. The method for operating the system using two operating modes: low flow rate and high flow rate. While operating in the low flow rate operating mode, the speed of a DEF pump remains constant and DEF delivery to the exhaust system is adjusted by controlling a backflow valve. While operating in the high flow rate operating mode, the backflow valve is closed and the speed of the pump is adjusted to regulate DEF delivery to the exhaust system.

A method for operating a device configured to deliver a liquid includes: a) back-suctioning a liquid situated in a pressure line section counter to a usual delivery direction by at least one pump; b) monitoring at least one operating parameter of the at least one pump during the back-suctioning, the at least one operating parameter being representative of a counterpressure that the at least one pump operates against during the back-suctioning; and c) detecting an increase in the counterpressure, and stopping the back-suctioning.

A method for operating a device that conveys a fluid includes: A) detecting activation of the device; B) filling a conveying line with the fluid by operating at least one pump in a conveying direction from at least one tank to at least one injector, and detecting complete filling of the conveying line based on at least one sudden pressure increase at at least one pressure sensor; C) operating the pump and making available fluid at the injector; D) detecting deactivation of the device; and E) partially emptying the conveying line by sucking back the fluid by operation of the at least one pump in a direction counter to the conveying direction. The emptying is stopped if pressure measured at the at least one pressure sensor corresponds to an ambient pressure.

A gas sensor, and a method for measuring the concentrations of a plurality of target components in a gas to be measured are disclosed. The gas sensor is provided with: a specific component measurement means which measures the concentration of a specific component in a measurement chamber; a preliminary oxygen concentration control means which controls the oxygen concentration in a preliminary adjustment chamber; a drive control means which controls the driving and stopping of the preliminary oxygen concentration control means; and a target component acquisition means which, on the basis of the difference between sensor outputs from the specific component measurement means when the preliminary oxygen concentration control means is being driven and when the preliminary oxygen concentration control means is stopped, and one of the respective sensor outputs, acquires the concentrations of a first target component and a second target component.

To provide an exhaust purifying system and a method for controlling the exhaust purifying system that avoid occurrence of clogging, breakage, or the like of a reducing agent injection valve caused by the solidification of a reducing agent and prevent reduction in the efficiency of reducing agent recovery processing and exhaust gas purification. An exhaust purifying system and a method for controlling the exhaust purifying system according to an aspect of the present invention is configured to detect the injection valve temperature of the reducing agent injection valve according to detection of turn-off of an ignition switch for stopping the internal combustion engine or detection of an injection stop of the reducing agent injection valve, whichever is earlier, calculate the waiting time until reducing agent recovery processing starts based on the injection valve temperature, and permits the reducing agent recovery processing under condition of the detection of turn-off of the ignition switch and an elapse of the waiting time.