Get to know about how Variable Injection Timing controls the Nox Emissions in the Marine Diesel Engines.
Variable Injection Timing is among some of the methods which are used to improve the engine performance, plus improves the Nox Emissions from the engine. Very important as per the new Marpol regulations.
How To Control Nox Emissions
As we know that to reduce the Nox emission the combustion temperature is the key. Lower the temp lesser the emission. By using VIT we can adjust the beginning of the injection as well as the end of the injection. So we try to inject fuel before TDC. So, that we can get the peak pressure at a much lower load than MCR, which we call as CSR.
By running the engine at lower load with the maximum peak pressure we can have a better SOFC, better combustion efficiency and more or less a complete combustion. Lesser chance of after burning (if no dribbling of injector). And more time for expansion cycle to occur. These all factors affect the NOx emission.
Here are some of the ways to achieve lower temperatures inside combustion space.
ü Reduce the cylinder temp. But peak pressure and fuel consumption will increase.
ü Using fuel water emulation, 1% water adding, but specific fuel oil consumption will be increased.
ü Water injection, on exhaust side which is called humidification.
ü Exhaust gas recirculation.
ü Increasing scavenge pressure.
ü By catalytic converter
This was all from this post on Nox Emissions Controls. Lot of companies now are putting emphasis on these as how to reduce them. In fact due to the technological advancements lot of improvements regarding the Nox emissions have been taken care off. In coming types we will see more such developments in order to reduce the Nox emissions. This was about control nox emissions.