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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.