Selective Catalytic Reduction (SCR)
The exhaust from diesel engines used aboard ships and in industry contains nitrogen oxide compounds, which steadily degrade air quality. Therefore the International Maritime Organization (IMO) is scheduled to enforce the stricter Tier III NOx emissions standards from 2016. HSD Engine has completed development of the unique DelNOx® system that uses Selective Catalytic Reduction at low temperature to meet the Tier III requirements.
IMO Environmental Regulations
Tier II emission standards were applied between 2001 and 2015, and the Tier III standards (3.4 g/kWh) has been applied from 2016. The ECA areas, so far limited to coastal waters of the United States and Europe, will include the Baltic Sea and the North Sea starting in 2021, and will expand to larger areas.
Working Principle of SCR
The Selective Catalytic Reduction system the reduction agent ammonia (NH3) and a catalyst to convert the nitrogen oxide (NO and NO2) content in the diesel exhaust into harmless nitrogen (N2) and water (H2O).
DelNOx® by HSD Engine has been proven to be very effective in removing NOx compounds from exhaust at low temperature.
SCR System Architecture
The selective catalytic reduction (SCR) system for NOx reduction consists of a reactor, urea supply and decomposition system, and control system.
The catalyst used in DelNOx® is a special low-temperature grade developed in-house to provide high reactivity with low-temperature (220ºC-450ºC) exhaust, meaning it can be installed after the turbocharger. In addition, catalyst compression strength tests have verified its durability when subjected to physical impacts.
The reactor vessel is loaded with the catalyst and reductant, while the soot blower removes the NOx particles that adhere to the surface of the catalyst. Computational fluid dynamics (CFD) analysis technology is used to examine the flow status inside the reactor vessel, which helps to optimize reactor vessel design.
Urea Supply & Decomposition System(Urea Supply & Decomposition System)
This system supplies and decomposes the urea solution that serves as the reductant that reacts with the nitrogen oxide compounds. It consists of a pump for transporting the urea solution, a pressure regulation valve, and electronic solenoid valve and a decomposition chamber.
To test and verify DelNOx, a system solely developed by HSD Engine, a 2-stroke low speed engine (15MW) was used. Meeting the IMO Tier III standards, DelNOx is a proven system verified by Germanischer Lloyd (GL).