Method of controlling a multi selective catalytic reduction system

摘要

A method of controlling a catalytic exhaust system including a first catalytic unit located upstream of a second catalytic unit, comprising:
i) providing a relationship between the temperature of the first catalytic unit, the amount of NH3 stored in the second catalytic unit and the corresponding limit value of the amount of NH3 permitted in the first unit;
ii) measuring or estimating the amount of NH3 in the second catalytic unit;
iii) measuring or estimating the temperature of the first catalytic unit;
iv) using said relationship and measured/estimated parameters of steps ii) and iii) to providing a said limit value for the amount of NH3 to be stored in said first catalytic unit
v) using said parameter from iv) in the control of said system.