Selective Catalytic Reduction

In an effort to reduce NOx emissions further, the Tier III requirements have been established for ships keel laid after 2016 by The International Maritime Organization (IMO). The Tier III requirements have been established for ships operating in Emission Control Areas (ECA).

 

More engine manufacturers and ship owners are looking towards the SCR as a means to reduce the NOx emissions. The traditional approach to controlling the SCR is by means of the engine load signal, where the amount of urea injected into the SCR is controlled as a function of the load. An alternative and cost efficient approach is to install a marine emission sensor after the SCR and feed back the NOx signal to the urea dosing controller. This way you can control the dosing of urea more accurately and obtain a better transient performance as the regulation is based on the exhaust out of the SCR. In addition, the sensor can measure an ammonia slip and thereby issue a warning, which will prevent damage to equipment further down the stack.