Scrubber
Scrubber
Scrubbers are devices to control air pollution and have been used to remove some particulates and gases from industrial exhaust streams for decades.
Marine scrubbers, also called Exhaust Gas Cleaning systems (ESGS), are used to remove particulate matter and harmful components of exhaust gas in marine engines – such as sulphur oxides (SOx) and nitrogen oxides (NOx).
The International Maritime Organization (IMO) regulations mandate that the sulphur content in fuels, which is carried by merchant vessels, has to be limited to 0.50% globally (known as “IMO 2020”) and 0.10 % m/m in ECAs (Emission Control Areas; The Baltic Sea Area, The North Sea area, The United States, Canada, and the United States Caribbean Sea area). Exhaust gas scrubbers are hence being installed on a substantial number of ships to comply with international regulations and standards economically. Exhaust gas streams are passed inside the scrubber where an alkaline scrubbing material is present to neutralize the acidic nature of the exhaust gasses and remove any particulate matter from the exhaust.
Marine scrubbers include several technical routes: Wet Scrubber System, Dry Scrubber System, Membrane Scrubber System. Wet Scrubber System dominates the market since it is recognized as the most efficient. There are three types of wet scrubber systems: open loop, closed loop and hybrid.
• open loop: uses seawater for scrubbing
• closed loop: uses alkali (NaOH solution or Mg(OH)2 slurry) for scrubbing
• hybrid: uses seawater or alkali with flexibility for scrubbing
In closed loop system and hybrid system, NaOH is used to be the preferred alkali due to its abundant availability. However, its disadvantages are also obvious: 1) Special care for handling and storage of NaOH solution, a hazardous substance; 2) More space required.
Magnesium Hydroxide is mild and safe, so no special precautions have to be taken from production to transport to storage. Meanwhile, it is still a very effective alkali due to its two hydroxide ions. When consuming the same quantity of SO2:
- on 100% solid substance basis, the consumption of NaOH is about 1.37 times that of Mg(OH)2;
- on liquid basis, the volume of NaOH solution is about 1.7 times that of Mg(OH)2 slurry.
Overall, Magnesium Hydroxide is more cost effective.
IMC offers customers high-grade magnesium hydroxide slurries with low carbon footprint for marine scrubbers.
Recommended Products
