Marine Emissions (NOx,Sox,Cox )
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| Marine Emissions (NOx,Sox,Cox ) |
The primary pollutants from Marine engines which causes Marine Emissions are :
·
oxides
of nitrogen (NOx).
·
oxides
of sulfur (SOx) .
·
oxides
of Carbon (Cox) .
Oxides of Nitrogen (NOx)
Description
NOx is a
general term that encompasses the following compounds: nitric oxide (NO),
nitrogen dioxide (NO2) and other oxides of Nitrogen.
Residence time
The average residence time of NO and NO2
in the atmosphere is on the order of days.
Formation in Engines:
In the marine engine, NOx is formed due to high
Nitrogen contents in the fuel.
A majority of
the NOx emission generated by internal combustion engines is through the
thermal process.
Nitrogen Oxide
(NO) is formed in engines as a result of high in-cylinder combustion
temperatures and high excess air ratios
Sulfur Oxides
(SOx)
Description
Sulfur dioxide (SO2) is a gaseous compound of
sulfur and oxygen .
Marine engines use either marine diesel or marine
heavy fuel oil. Both of these fuels have much higher sulphur contents than
transportation fuels used on land .
Residence time
The average residence time of SO2 is 25 hours
Formation in Engines:
The emissions of SO2 and SO3 are
directly linked to the content of sulfur in the fuel.
all sulfur contained in the fuel is oxidized to SO2
and SO3 during and immediately after the combustion.
Since sulfur is
seen as an important lubricant for the engine and it is not seen as feasible
for the near-future for ships to have the capabilities to remove the sulfur
from the fuel from the ship, the oil-industry will be the key stakeholder in
reducing SOx emissions.
Carbon Oxides
(Cox):
COx
emissions result from incomplete combustion.
COx
results when there is insufficient residence
time at high temperature or incomplete mixing to complete the final step in fuel carbon
oxidation.
COx emissions
are also dependent on the loading of marine engine operating, in case of a full
load will experience greater fuel efficiencies which will reduce
the formation of COx .
Emission Source
SOx Function of fuel oil sulphur content
COx Function of combustion
NOx Function of peak combustion
temperatures, oxygen content and residence
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