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REDUCED EMISSIONS OF OXIDESOF NITROGEN IN SHIP ENGINES
Presented by:- VIVEK RAJU
S7 Mechanical
RIT, Kottayam
Roll No. 61
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INTRODUCTION
Oxides of nitrogen emission from ship engines
are significant on a global level. These emissionsparticipate in the formation of photochemical
smog and acid rain. Here we look at to some
ways by which these emissions can be reduced.
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Mechanism of NOx Formation
in Diesel Engines.
At the temperature of the Burning of fuel
spray (about 2000 K to 2500 K).
Nitrogen + Oxygenp Oxides of Nitrogen
(mostly Nitric Oxide)
During expansion process and in exhaust.
Nitric Oxidep NO2 and N2O
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Three Phases of Combustion
1. Evaporation and the Mixing of early
injected fuel with air.
2. Uncontrolled Combustion.
3. Controlled Combustion.
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NOx Control Measures
1. Engine Tuning.
a. Intelligent Engines.
b. Injection Timing Retard.
c. Fuel Injector Valves and Nozzles.
d. Injection Rate Shaping.
e. Compression Ratio, Injection Timing and Injection
Rate.f. Scavenge Air Temperature.
2. Water Injection, Fuel/Water Emulsion, Humidification.
3. Exhaust Gas Recirculation.
4. Selective Catalytic Reaction.
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Intelligent Engines.
Electronically controlled Camshaftlessengines allow great flexibility for
optimization of combustion process over
the full range of operating conditions.
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Injection Timing Retard
NOx formation depends on residence time.By retarding injection timing NOx formation
is reduced.
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Fuel Injector Valves and Nozzles
Recent developments in low engine emission of
nitrogen is because of the fine tuning of the fuel
injection process.
Slow speed engines uses two or three fuel injector.
For medium speed engines the space around the
burning area are reduced.
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Injection Rate Shaping
Sequencial and pre-injection gave less
NOx emissions and fuel consumption.
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Compression Ratio, Injection Timing
and Injection Rate
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Scavenge Air Temperature
Reduced Scavenged air temperature
reduces combustion temperature and thus
less NOx emission.
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2. Water Injection, Fuel/Water
Emulsion, Humidification
Introduction of water into the combustion
chamber reduces combustion temperature.
Water can be injected by
Direct injection in to the Cyllinder or
By water / fuel emulsion.
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3. Exhaust Gas Re-circulation
Exhaust Gas Re-circulation lowers the
combustion temperature thus loweringNOx emission.
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4. Selective Catalytic Reaction
It involves mixing of Ammonia with the
exhaust gas which is passed over a catalyst
where more than 90% of the NOx can be
removed.
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CONCLUSION
Most engine manufactures are nowproducing standard engines. This has
been achieved by engine tuning
measures.
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THANK YOU.
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