A method and a control arrangement for a process of selective catalytic reduction after-treatment of an exhaust gas

A computer program product comprising computer program code stored on a non-transitory computer-readable medium, said computer program product used for a process of selective catalytic reduction (SCR) after-treatment of an exhaust gas of an exhaust gas stream from a combustion engine, wherein the selective catalytic reduction after-treatment process comprises:

• injecting an additive in liquid form into the exhaust gas stream from the combustion engine;
• evaporating the additive to form a reducing agent, the reducing agent being added to the exhaust gas stream;
• and reducing nitrogen oxides of the exhaust gas stream in a reduction catalyst device through the use of the reducing agent added to the exhaust gas stream, said computer program code comprising computer instructions to cause one or more control units to perform the following operations:
• 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, by usage of an integral controller, an integral controller output which is proportional to the integral of the integrand with time;
• and
• requesting a countermeasure at least partly based on the integral controller output to counteract solid deposits derived from the additive.

A control arrangement for a process of selective catalytic reduction (SCR) after-treatment of an exhaust gas of an exhaust gas stream from a combustion engine wherein the selective catalytic reduction after-treatment process comprises:

• injecting an additive in liquid form into the exhaust gas stream from the combustion engine;
• evaporating the additive to form a reducing agent, the reducing agent being added to the exhaust gas stream;
• and
• reducing nitrogen oxides of the exhaust gas stream in a reduction catalyst device through the use of the reducing agent added to the exhaust gas stream,
• wherein the control arrangement is configured to:
• define 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;
• produce, by usage of an integral controller, an integral controller output which is proportional to the integral of the integrand with time;
• and
• request a countermeasure at least partly based on the integral controller output to counteract solid deposits derived from the additive.