procedure for starting up of dosage of reducing agent in ettscr system and a scr system

摘要

The invention relates to a method and device for thawing frozen reducing agent in an SCR system. The reducing agent is heated with a heating medium circulating (281) through the container (205) when a need of heating is determined. The temperature (Tred) and the level (L) of the reducing agent in the container (205) are determined and the accumulated amount (V) of thawed reducing agent is continuously determined. Start up of circulation of the reducing agent is suitable when the temperature (Tred) exceeds a predetermined first temperature value (Th1), and/or when the determined accumulated amount (V) of thawed reducing agent exceeds a predetermined first quantity value (VTh1). The dosage of the reducing agent is suitable when the determined temperature (Tred) exceeds a predetermined second temperature value (Th2), and/or when the determined accumulated amount (V) of thawed reducing agent exceeds a predetermined second quantity value (VTh2). The first temperature value (Th1), the second temperature value (Th2), the first quantity value (VTh1), and the second quantity value (VTh2) are determined based on said determined level (L) of the reducing agent in the container.