How it works

Selective Catalytic Reduction (SCR) is an efficient way of reducing emissions of Nitrogen Oxides (NOx) from diesel engines. It works by injecting a reductant, also known as Diesel exhaust fluid (DEF) in the exhaust stream which reacts with the NOx in a catalyst. The chemical reaction converts NOx to harmless Nitrogen and water.

SCRmarine is a fully automatic system capable of high NOx reduction. The control system communicates with the engine and calculates the required DEF dosing rate for all operating modes including transient conditions.

The model based injection system is air assisted to allow a high degree of atomization of the injected DEF which makes the chemical conversion more efficient. Compressed air is also used to flush the system after engine shut down to eliminate any possibility for blockage by DEF deposits or damages caused by freezing. The DEF Supply Pump supplies DEF from the tank to the dosing unit which controls the dosing rate. The Injection nozzle leads air and DEF to the exhaust stream where it is injected at the mixer unit inlet.

The mixing unit ensures that the injected DEF is decomposed and converted to ammonia and then mixed with the exhaust gas before reaching the catalyst chamber. The catalyst chamber is where the conversion from NOx and ammonia to harmless nitrogen and water takes place by a chemical reaction. The control system continuously monitors and stores a number of key parameters for easy troubleshooting and to avoid unplanned downtime. 


Modular design
Suitable for retrofit
Automatic operation
Low mainteinance
Air assisted injection
Developed in house
Quick deliveries

SCR Marine
NOx reduction technology by STT Emtec
Download to read >>

Mailing address: STT Emtec AB,
Box 46, 862 02 Njurunda
Tel: +46 60 64 10 40

Copyright © STT Emtec AB 2023

Visiting address: Njurundavägen 16,
862 40 Njurunda