Ammoniaakki

Ammoniaakki is a term of Finnish origin that translates to "ammonia slip" or "ammonia breakthrough" in English. It refers to the phenomenon where unreacted ammonia exits a system designed to remove it, most commonly in industrial processes like Selective Catalytic Reduction (SCR) systems used for emission control in power plants and diesel engines.

In SCR systems, ammonia is injected into the exhaust stream to react with nitrogen oxides (NOx) and convert them into harmless nitrogen and water vapor. Ammoniaakki occurs when the ammonia injection rate is too high, or when the reaction conditions are not optimal, leading to excess ammonia passing through the catalyst without reacting. This unreacted ammonia can then be released into the atmosphere.

The presence of ammoniaakki is undesirable for several reasons. It contributes to air pollution, as ammonia can react with other atmospheric components to form particulate matter, which has negative impacts on respiratory health and visibility. Furthermore, it can lead to fouling and corrosion of downstream equipment. Monitoring and controlling ammonia levels are crucial for efficient and environmentally sound operation of SCR systems, and the concept of ammoniaakki highlights the importance of precise process management.