A SEMINAR ON NOx REDUCTION BY FUEL WATER EMULSION INJECTION PRESENTED BY SHAIK NAYEEM ABBAS UNI:- 3KB04ME046 KBNCE

Introduction The nitrogen oxide reduction technology based on fuel water emulsion injection (FWE), developed by MAN B&W Diesel. More than 95 % of the world’s trade goes by sea and there are approximately 86,000 ocean going merchant ships. About 97 % of them are propelled by large-bore, highly supercharged diesel engines such as shown.

Formation of NOx Nitrogen oxides (NOx) are formed when nitrogen (N2) and oxygen (O2) are combined at high temperatures and pressure during the combustion of fuel. All fuels, such as gasoline, diesel, biodiesel, propane, coal, and ethanol, emit NOx when burned.

Formation of NOx

Prompt NOx Frequently observed in fuel-rich flames and at low temperatures. Three possible sources: Non-equilibrium nascent oxygen (O) and hydroxyl (OH) radical concentrations accelerate the rate of thermal NO mechanism. Reactions of hydrocarbon radicals with molecular nitrogen Reaction of nascent oxygen (O) with molecular nitrogen

Fuel NOx Form nitrogen bearing fuels such as certain coals and oil. Can contribute upto 50% of total emissions when combusting oil As much as 80% when combusting coal.

Thermal NOx Is highly temperature dependent. Formed through high temperature oxidation of the diatomic nitrogen found in combustion air.

Properties of NOx: Gas Most nitrogen oxides are odorless NO2 combined with particulate, appears reddish-brown (smog)

Harmful effects of NOx Aggravate asthmatic conditions React with the Oxygen in the air to produce ozone Form nitric acid when dissolved in water. Cause acid rain Form clouds of smog in the summer

Fuel Water Emulsion Injection

1) Primary Method Modification of combustion Modification of Air intake system Exhaust Gas Re-circulation 2) Secondary Method Fuel Water Emulsion Injection 3) Pre treatment Method Denitration of Fuel Alternative Fuel

Principle Add water to a fuel The evaporation of water reduces the temperature maximum in the combustion zone. The formation of nitrogen oxides is decreased by reduced reaction rates The actually required water flow is calculated as a function of power

Method of injection Will provide an emulsified diesel fuel to the engine’s injector pump, with a water content from 0 to 40%. Emulsification of the fuel is created mechanically in a fuel-mixing chamber. Diesel pumped to the fuel-mixing chamber from the fuel tank where water is added to the fuel through a probe controlled by a microprocessor with controlling software. Mechanical agitation technique results in the breakup of the water into small droplets that are dispersed throughout the diesel fuel, representing an emulsion.

Diesel engine

Combustion When liquid is sprayed into a co-flowing air stream, the spray forms a jet inside the chamber. The jet consists of evaporating liquid fuel droplets suspended in a hot environment. Phase slip and temperature gradients exist between the droplets and the surrounding gas, leading to momentum, mass and energy transfer between the two phases.

Effect on Exhaust Emissions

%Reduction in NOx Vs Water

Effect In the engine This technique involves injecting water using the same injector as the fuel, eliminates the need for an additional fuel injector. Electronic fuel injection is required to control the injection. Altering the fuel then water injection process, is likely to come at a significant extra cost.

Advantages Reduction of nitrogen oxide emissions Reduction of soot emissions Controlling of the water quantity by the engine parameters Usable in stationary as well as mobile application

Disadvantages High initial cost Severe corrosion problem Separate pump for the fuel and water are needed along with the modification to the fuel delivery line and in the injectors.

Conclusion-Water Fuel Emulsion Water content to 20%: 15-38% NOx reduction 1-3% efficiency reduction Smaller particles: Promotes higher NOx reduction Little effect on efficiency reduction NOx reduction is a function of chamber and flame temperature.

References I.C.Engine By V.Ganeshan I.C.Engine By Rajput Emulsion and Emulsion Stability by Johan Siojblom Dynamics of emulsification and de emulsification of water in crude oil emission by Bhardwaj MAN B&W Diesel A/S, Copenhagen, Denmark Emission Control

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