Abstract: Disclosed is a method for use in a process of selective catalytic reduction (SCR) after-treatment of an exhaust gas of an exhaust gas stream, where the process comprises the reduction of nitrogen oxides of the exhaust gas stream through the use of a reducing agent derived from an additive. The disclosed method comprises: defining an integrand to be the difference between the rate of injection of the additive and the rate of evaporation of the additive to the reducing agent multiplied by a coefficient (s), wherein the value of the coefficient (s) is between zero and one; producing an integral controller output proportional to the integral of the integrand with time; requesting a countermeasure based on the integral controller output to counteract solid deposits derived from the additive.

Abstract: Disclosed is a method for use in a process of selective catalytic reduction (SCR) after-treatment of an exhaust gas of an exhaust gas stream, where the process comprises the reduction of nitrogen oxides of the exhaust gas stream through the use of a reducing agent derived from an additive. The disclosed method comprises: defining an integrand to be the difference between the rate of injection of the additive and the rate of evaporation of the additive to the reducing agent multiplied by a coefficient (s), wherein the value of the coefficient (s) is between zero and one; producing an integral controller output proportional to the integral of the integrand with time; requesting a countermeasure based on the integral controller output to counteract solid deposits derived from the additive.

Abstract: A method and a system for control of a dosage device and/or an engine that produces an exhaust stream (203) treated by an exhaust treatment system (250) that injects at least one additive into the exhaust stream (203) with a dosage device (271) to evaporate in an evaporation chamber (280). The method includes determining a time dependent condition of a position at an internal wall (281) of the evaporation chamber (280), the condition being determined based on the internal temperature related to the position, the internal temperature being determined based on a temperature model for the evaporation chamber (280) and an exhaust temperature for the exhaust stream (203) upstream of the evaporation chamber (208); determining a risk for at least one spatially resolved critical condition related to the position based on the time dependent condition, and controlling the dosage device (271) and/or the engine based on the determined risk.