Method for controlling selective catalytic reduction system of exhaust treatment system for diesel engine system, involves determining pass/fail-status of reduction agent supply and catalyzer based on amount of ammonia slip and threshold

摘要

The method involves determining conversion efficiency of a selective catalytic reduction (SCR) catalyzer (36) based on measurements of cross-sensitive nitrogen oxide sensors (44, 45) during a period with preset operating conditions. Amount of ammonia slip over the SCR catalyzer is determined when the conversion efficiency is smaller than a predetermined threshold. A pass/fail-status of a reduction agent i.e. ammonia, supply and the SCR catalyzer is determined or generated based on amount of ammonia slip and an ammonia slip threshold.